BACKGROUND OF THE INVENTION Various techniques are known for the manufacture of drip irrigation tubing. The following U. S. and foreign patents are believed to represent the current state of the art: U. S. Patents 5,891,481 ; 5,817,270 ; 5,785,906; 5,7447779-1 5,676,897 ; 5,460,501 ; 5, 324, 379; 5,324, 371 ; 5,282,916; 5,271,786; 5,122, 044 ; 5,028, 376; 5,022,940 ; 4, 888, 148 : 4,828,770; 4,423,838 ; 4,314,958; 4,152,380 ; 4,020,136 and 3, 981,452.

Israel Patents 100126; 95972; 86549 and 77827.

European Published Patent Application 0 480 632 and O 344 605.

SUMMARY OF THE INVENTION The present invention seeks to provide an improved method and apparatus for the manufacturing of plastic irrigation tubing.

There is thus provided in accordance with a preferred embodiment of the present invention a method for manufacturing plastic tubes including the steps of : extruding a plastic tube from an extrusion head. the tube having a first diameter and a first thickness as it leaves the extrusion head at a first linear velocity; and downstream of the extrusion head, causing the plastic tube to have a second diameter and a second thickness as it moves at a second linear velocity, slower than the first linear velocity.

There is also provided in accordance with a preferred embodiment of the present invention a method for manufacturing plastic tubes including the steps of: extruding a plastic tube from an extrusion head, the tube having a first cross-sectional area as it leaves the extrusion head ; and downstream of the extrusion head. causing the plastic tube to have a second cross-sectional area, greater than the first cross-sectional area.

There is additionally provided in accordance with a preferred embodiment of the present invention a method for manufacturing plastic tubes including the steps of : extruding a plastic tube from an extrusion head, the tube having a first diameter and a first thickness as it leaves the extrusion head at a first linear velocity; and downstream of the extrusion head, causing the plastic tube to have a second diameter and a second thickness as it moves at a second linear velocity, characterized in that at least one of the following conditions is met: the second diameter is greater than the first diameter ; the second thickness is greater than the first thickness: and the second linear velocity is less than the first linear velocity.

There is further provided in accordance with a preferred embodiment of the present invention a method for manufacturing a drip irrigation tube including the steps of : extruding a plastic tube from an extrusion head, the tube having a first diameter and a first thickness as it leaves the extrusion head at a first linear velocity; downstream of the extrusion head, causing the plastic tube to have a second diameter and a second thickness as it moves at a second linear velocity, slower than the first linear velocity; and causing individual drip irrigation elements to adhere to an interior of the plastic tube.

Additionally in accordance with a preferred embodiment of the present invention there is provided a method for manufacturing a drip irrigation tube including the steps of : extruding a plastic tube from an extrusion head, the tube having a first cross-sectional area as it leaves the extrusion head; and downstream of the extrusion head, causing the plastic tube to have a second cross-sectional area, greater than the first cross-sectional area : and causing individual drip irrigation elements to adhere to an interior of the plastic tube.

Further in accordance with a preferred embodiment of the present invention there is provided a method for manufacturing a drip irrigation tube including the steps of : extruding a plastic tube from an extrusion head, the tube having a first diameter and a first thickness as it leaves the extrusion head at a first linear velocity; downstream of the extrusion head. causing the plastic tube to have a second diameter and a second thickness as it moves at a second linear velocity, characterized in that at least one of the following conditions is met: the second diameter is greater than the first diameter; the second thickness is greater than the first thickness ; and the second linear velocity is less than the first linear velocity; and causing individual drip irrigation elements to adhere to an interior of the plastic tube.

There is additionally provided in accordance with a preferred embodiment of the present invention apparatus for manufacturing plastic tubes including: extruding a plastic tube from an extrusion head, the tube having a first diameter and a first thickness as it leaves the extrusion head at a first linear velocity; and downstream of the extrusion head, causing the plastic tube to have a second diameter and a second thickness as it moves at a second linear velocity, slower than the first linear velocity.

There is also provided in accordance with a preferred embodiment of the present invention apparatus for manufacturing plastic tubes including: an extruder, extruding a plastic tube from an extrusion head, the tube having a first cross-sectional area as it leaves the extrusion head; and a calibrator, downstream of the extrusion head, causing the plastic tube to have a second cross-sectional area. greater than the first cross-sectional area.

There is additionally provided in accordance with a preferred embodiment of the present invention apparatus for manufacturing plastic tubes including: an extruder, extruding a plastic tube from an extrusion head, the tube having a first diameter and a first thickness as it leaves the extrusion head at a first linear velocity; and a calibrator, downstream of the extrusion head, causing the plastic tube to have a second diameter and a second thickness as it moves at a second linear velocity, characterized in that at least one of the following conditions is met: the second diameter is greater than the first diameter; the second thickness is greater than the first thickness ; and the second linear velocity is less than the first linear velocity.

There is further provided in accordance with a preferred embodiment of the present invention apparatus for manufacturing a drip irrigation tube including: an extruder, extruding a plastic tube from an extrusion head, the tube having a first diameter and a first thickness as it leaves the extrusion head at a first linear velocity; a calibrator, downstream of the extrusion head, causing the plastic tube to have a second diameter and a second thickness as it moves at a second linear velocity, slower than the first linear velocity; and an insertion assembly, causing individual drip irrigation elements to adhere to an interior of the plastic tube.

Additionally in accordance with a preferred embodiment of the present invention there is provided apparatus for manufacturing a drip irrigation tube including: an extruder, extruding a plastic tube from an extrusion head, the tube having a first cross-sectional area as it leaves the extrusion head; and a calibrator, downstream of the extrusion head, causing the plastic tube to have a second cross-sectional area, greater than the first cross-sectional area; and an insertion assembly, causing individual drip irrigation elements to adhere to an interior of the plastic tube.

Further in accordance with a preferred embodiment of the present invention there is provided apparatus for manufacturing a drip irrigation tube including: an extruder, extruding a plastic tube from an extrusion head, the tube having a first diameter and a first thickness as it leaves the extrusion head at a first linear velocity; a calibrator, downstream of the extrusion head, causing the plastic tube to have a second diameter and a second thickness as it moves at a second linear velocity, characterized in that at least one of the following conditions is met: the second diameter is greater than the first diameter; the second thickness is greater than the first thickness; and the second linear velocity is less than the first linear velocity; and an insertion assembly, causing individual drip irrigation elements to adhere to an interior of the plastic tube.

In accordance with a preferred embodiment of the present invention, the second diameter is greater than the first diameter.

In accordance with an alternative preferred embodiment of the present invention, the second diameter is less than the first diameter.

In accordance with a preferred embodiment of the present invention, the second thickness is greater than the first thickness.

In accordance with an alternative preferred embodiment of the present invention, the second thickness is less than the first thickness.

In accordance with a preferred embodiment of the present invention, the tube moves at the first velocity along a first axis and moves at the second velocity along a second axis coaxial with the first axis.

In accordance with an alternative preferred embodiment of the present invention, the tube moves at the first velocity along a first axis and moves at the second velocity along a second axis parallel to and disposed downward with respect to the first axis.

In accordance with a preferred embodiment of the invention, the insertion assembly is operative to cause the drip irrigation elements to undergo linear motion of generally the same velocity as that of the tube upon initial contact with the interior thereof.

BRIEF DESCRIPTION OF THE DRAWINGS The present invention will be understood and appreciated more fully from the following detailed description. taken in conjunction with the drawings in which: Figs. 1A, 1B and 1C are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 1 B-1 B and 1 C-1 C in Fig. 1 A ; Figs. 2A. 2B and 2C are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 2B-2B and 2C-2C in Fig. 2A; Figs. 3A, 3B and 3C are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 3B-3B and 3C-3C in Fig. 3A ; Figs. 4A. 4B and 4C are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 4B-4B and 4C-4C in Fig. 4A; Figs. SA, 5B and 5C are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 5B-5B and 5C-5C in Fig. SA ; Figs. 6A, 6B and 6C are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 6B-6B and 6C-6C in Fig. 6A; Figs. 7A, 7B and 7C are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 7B-7B and 7C-7C in Fig. 7A; Figs. 8A. 8B and 8C are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 8B-8B and 8C-8C in Fig. 8A; Figs. 9A. 9B and 9C are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 9B-9B and 9C-9C in Fig. 9A; Figs. IOA, lOB and 1 OC are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and cf the tube at first and second stages of its manufacture, taken at lines 1 OB-1 OB and l OC-l OC in Fig. 10A ; Fig. 11 is a simplified and generalized sectional illustration of apparatus and a method for producing a drip irrigation tube in accordance with a preferred embodiment of the present invention; Figs. 12A, 12B and 12C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 1 A, 1B and 1C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween; Figs. 13A, 13B and 13C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 1 A, 1B and 1 C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween; Figs. 14A, 14B and 14C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 1 A, 1B and 1 C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween; Figs. 1 5A, 15B and 15C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 2A, 2B and 2C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween : Figs. 16A, 16B and 16C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 2A, 2B and 2C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween; Figs. 17A, 17B and 17C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 2A, 2B and 2C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween; Figs. 18A, 18B and 18C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 3A. 3B and 3C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween; Figs. 19A, 19B and 19C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 3A, 3B and 3C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween; Figs. 20A, 20B and 20C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 3A, 3B and 3C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween ; Figs. 21A, 21B and 21C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 4A, 4B and 4C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween; Figs. 22A, 22B and 22C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 4A, 4B and 4C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween ; Figs. 23A, 23B and 23C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 4A, 4B and 4C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween; Figs. 24A, 24B and 24C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 5A, 5B and 5C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween; Figs. 25A, 25B and 25C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 5A, 5B and 5C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween; Figs. 26A, 26B and 26C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. SA, 5B and 5C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween; Figs. 27A. 27B and 27C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 6A, 6B and 6C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween; Figs. 28A, 28B and 28C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 6A, 6B and 6C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween; Figs. 29A, 29B and 29C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 6A, 6B and 6C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween; Figs. 30A, 30B and 30C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 7A, 7B and 7C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween; Figs. 31A, 31B and 31C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 7A 7B anc 7C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween; Figs. 32A, 32B and 32C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 7A, 7B and 7C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween; Figs. 33A 33B and 33C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 8A, 8B and 8C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween; Figs. 34A, 34B and 34C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 8A, 8B and 8C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween; Figs. 35A, 35B and 35C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 8A, 8B and 8C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween; Figs. 36A, 36B and 36C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 9A. 9B and 9C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween; Figs. 37A, 37B and 37C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 9A, 9B and 9C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween; Figs. 38A, 38B and 38C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 9A, 9B and 9C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween ; Figs. 39A, 39B and 39C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 1 OA, 1 OB and l OC, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween; Figs. 40A, 40B and 40C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 10A, 1 OB and l OC, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween; Figs. 41 A, 41 B and 41C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 1 OA, l OB and l OC, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween; Figs. 42A, 42B and 42C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 1 A, 1 B and 1 C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant ; Figs. 43A, 43B and 43C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 2A, 2B and 2C. at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant ; Figs. 44A, 44B and 44C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 3A, 3B and 3C. at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant; Figs. 45A, 45B and 45C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 4A, 4B and 4C. at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant ; Figs. 46A, 46B and 46C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 5A, 5B and 5C. at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant ; Figs. 47A. 47B and 47C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 6A. 6B and 6C. at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant; Figs. 48A, 48B and 48C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 7A, 7B and 7C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant ; Figs. 49A, 49B and 49C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 8A, 8B and 8C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant : Figs. 50A, 50B and 50C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 9A, 9B and 9C. at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant; and Figs. 51 A, 51 B and 51C are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 10A, l OB and 1 OC, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

It is to be noted that the differences in the cross sections at different stages in the manufacture are not necessarily drawn to scale and are exaggerated substantially to illustrate varic us features of the present invention. The actual differences in tube thickness and diameters of the tube are normally such that they would not readily be discerned in the drawing absent such exaggeration.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Reference is now made to Figs. 1A, 1B and 1C. which are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with a preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 1 B-1 B and 1 C-1 C in Fig.

1A.

As seen in Fig. 1 A, an extruder head 10, forming part of a conventional plastic extrusion machine (not shown). such as an extruder commercially available from NEXTROM of Lausanne, Switzerland, extrudes a seamless tube 12. The tube 12 leaves the extruder at a first linear velocity V 1 along an axis 14. The outside diameter D and thickness T of the tube as it leaves the extruder are shown in Fig. 1 B at lines 1B-1B to be D I and T1. respectively.

Downstream of the extruder head 10 and typically spaced therefrom by approximately 30-70 mm is a calibrator 16, which assists in determining the outside diameter D and thickness T of the final tube. The outside diameter D2 and thickness T2 of the final tube as it leaves the calibrator 16 are also determined by the second linear velocity V2 at which the tube is drawn through the calibrator by drawing apparatus (not shown) downstream of the calibrator 16.

It is a particular feature of the present invention that the cross-sectional area of the tube as it leaves the calibrator 16 is larger than the cross-sectional area of the tube as it leaves the extruder head 10. This feature may be realized when at least one of the following conditions is met: the second diameter D2 is greater than the first diameter D 1 ; the second thickness T2 is greater than the first thickness T1.

It may be appreciated that the foregoing feature is realized when the second linear velocity V2 is less than the first linear velocity VI.

In the illustrated embodiment of Fig. 1 A, it is seen that V2 < V1.

Thus, it may be appreciated that the cross-sectional area of the tube downstream of the calibrator 16, shown in Fig. 1 C at lines 1 C-1 C, is greater than the cross-sectional area of the tube shown in Fig. 1 B at lines 1 B-1 B.

In the illustrated embodiment of Fig. lA, it is also seen that D2 = Dl andT2>TI.

It is also noted that in the embodiment of Fig. 1 A. the calibrator 16 is aligned coaxially with the extruder head 10, along axis 14.

Reference is now made to Figs. 2A, 2B and 2C, which are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with another preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 2B-2B and 2C-2C in Fig.

2A.

As seen in Fig. 2A, an extruder head 20, forming part of a conventional plastic extrusion machine (not shown). such as an extruder commercially available from NEXTROM of Lausanne, Switzerland, extrudes a seamless tube 22. The tube 22 leaves the extruder at a first linear velocity V I along an axis 24. The outside diameter D and thickness T of the tube as it leaves the extruder are shown in Fig. 2B at lines 2B-2B to be Dl and T1, respectively.

Downstream of the extruder head 20 and typically spaced therefrom by approximately 30-70 mm is a calibrator 26, which assists in determining the outside diameter D and thickness T of the final tube. The outside diameter D2 and thickness T2 of the final tube as it leaves the calibrator 26 are also determined by the second linear velocity V2 at which the tube is drawn through the calibrator bv drawing apparatus (not shown) downstream of the calibrator 26.

In the illustrated embodiment of Fig. 2A, it is seen that V2 < V I.

Thus. it may be appreciated that the cross-sectional area of the tube downstream of the calibrator 26, shown in Fig. 2C at lines 2C-2C, is greater than the cross-sectional area of the tube shown in Fig. 2B at lines 2B-2B.

In the illustrated embodiment of Fig. 2A, it is also seen that D2 > Dl andT2=Tl.

It is also noted that in the embodiment of Fig. 2A, the calibrator 26 is aligned coaxially with the extruder head 20, along axis 24.

Reference is now made to Figs. 3A, 3B and 3C, which are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with still another preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 3B-3B and 3C-3C in Fig. 3A.

As seen in Fig. 3A, an extruder head 30, forming part of a conventional plastic extrusion machine (not shown), such as an extruder commercially available from NEXTROM of Lausanne, Switzerland, extrudes a seamless tube 32. The tube 32leaves the extruder at a first linear velocity V 1 along an axis 34. The outside diameter D and thickness T of the tube as it leaves the extruder are shown in Fig. 3B at lines 3B-3B to be Dl and T1, respectively.

Downstream of the extruder head 30 and typically spaced therefrom by approximately 30-70 mm is a calibrator 36. which assists in determining the outside diameter D and thickness T of the final tube. The outside diameter D2 and thickness T2 of the final tube as it leaves the calibrator 36 are also determined by the second linear velocity V2 at which the tube is drawn through the calibrator by drawing apparatus (not shown) downstream of the calibrator 36.

In the illustrated embodiment of Fig. 3A, it is seen that V2 < V 1 Thus, it may be appreciated that the cross-sectional area of the tube downstream of the calibrator 36, shown in Fig. 3C at lines 3C-3C, is greater than the cross-sectional area of the tube shown in Fig. 3B at lines 3B-3B.

In the illustrated embodiment of Fig. 3A. it is also seen that D2 > DI and T2>TI.

It is also noted that in the embodiment of Fig. 3A. the calibrator 36 is aligned coaxially with the extruder head 30, along axis 34.

Reference is now made to Figs. 4A, 4B and 4C, which are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with yet another preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 4B-4B and 4C-4C in Fig. 4A.

As seen in Fig. 4A, an extruder head 40, forming part of a conventional plastic extrusion machine (not shown). such as an extruder commercially available from NEXTROM of Lausanr e, Switzerland, extrudes a seamless tube 42. The tube 42 leaves the extruder at a first linear velocity V I along an axis 44. The outside diameter D and thickness T of the tube as it leaves the extruder are shown in Fig. 4B at lines 4B-4B to be DI and Tl, respectively.

Downstream of the extruder head 40 and typically spaced therefrom by approximately 30-70 mm is a calibrator 46. which assists in determining the outside diameter D and thickness T of the final tube. The outside diameter D2 and thickness T2 of the final tube as it leaves the calibrator 46 are also determined by the second linear velocity V2 at which the tube is drawn through the calibrator by drawing apparatus (nut shown) downstream of the calibrator 46.

In the illustrated embodiment of Fig. 4A. it is seen that V2 < V1.

Thus, it may be appreciated that the cross-sectional area of the tube downstream of the calibrator 46, shown in Fig. 4C at lines 4C-4C, is greater than the cross-sectional area of the tube shown in Fig. 4B at lines 4B-4B.

In the illustrated embodiment of Fig. 4A. it is also seen that D2 < D 1 and T2 > Tl.

It is also noted that in the embodiment of Fig. 4A, the calibrator 46 is aligned coaxially with the extruder head 40, along axis 44.

Reference is now made to Figs. 5A, 5B and 5C, which are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with still another preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 5B-5B and 5C-5C in Fig. 5A.

As seen in Fig. 5A, an extruder head 50, forming part of a conventional plastic extrusion machine (not shown), such as an extruder commercially available from NEXTROM of Lausanne, Switzerland, extrudes a seamless tube 52. The tube 52 leaves the extruder at a first linear velocity V1 along an axis 54. The outside diameter D and thickness T of the tube as it leaves the extruder are shown in Fig. 5B at lines 5B-5B to be Dl and Tl. respectively.

Downstream of the extruder head 50 and typically spaced therefrom by approximately 30-70 mm is a calibrator 56, which assists in determining the outside diameter D and thickness T of the final tube. The outside diameter D2 and thickness T2 of the final tube as it leaves the calibrator 56 are also determined by the second linear velocity V2 at which the tube is drawn through the calibrator by drawing apparatus (not shown) downstream of the calibrator 56.

In the illustrated embodiment of Fig. 5A, it is seen that V2 < V I. Thus, it may be appreciated that the cross-sectional area of the tube downstream of the calibrator 56, shown in Fig. 5C at lines 5C-5C, is greater than the cross-sectional area of the tube shown in Fig. 5B at lines 5B-5B.

In the illustrated embodiment of Fig. 5A. it is also seen that D2 > Dl and T2 < TI.

It is also noted that in the embodiment of Fig. 5A, the calibrator 56 is aligned coaxially with the extruder head 50, along axis 54.

Reference is now made to Figs. 6A, 6B and 6C, which are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with still another preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 6B-6B and 6C-6C in Fig. 6A.

As seen in Fig. 6A, an extruder head 60, forming part of a conventional plastic extrusion machine (not shown), such as an extruder commercially available from NEXTROM of Lausanne. Switzerland, extrudes a seamless tube 62. The tube 62 leaves the extruder at a first linear velocity V I along an axis 64. The outside diameter D and thickness T of the tube as it leaves the extruder are shown in Fig. 6B at lines 6B-6B to be D1 and Tl. respectively.

Downstream of the extruder head 60 and typically spaced therefrom by approximately 30-70 mm is a calibrator 66, which assists in determining the outside diameter D and thickness T of the final tube. The outside diameter D2 and thickness of the final tube as it leaves the calibrator 66 are also determined by the second linear velocity V2 at which the tube is drawn through the calibrator by drawing apparatus (not shown) downstream of the calibrator 66.

In the illustrated embodiment of Fig. 6A, it is seen that V2 < VI.

Thus, it may be appreciated that the cross-sectional area of the tube downstream of the calibrator 66, shown in Fig. 6C at lines 6C-6C, is greater than the cross-sectional area of the tube shown in Fig. 6B at lines 6B-6B.

In the illustrated embodiment of Fig. 6A, it is also seen that D2 = DI and T2>TI.

It is also noted that in the embodiment of Fig. 6A, the calibrator 66 is aligned along an axis 68, parallel to and downwardly offset with relative to axis 64.

Reference is now made to Figs. 7A. 7B and 7C, which are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with still another preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 7B-7B and 7C-7C in Fig. 7A.

As seen in Fig. 7A, an extruder head 70, forming part of a conventional plastic extrusion machine (not shown), such as an extruder commercially available from NEXTROM of Lausanne, Switzerland, extrudes a seamless tube 72. The tube 72 leaves the extruder at a first linear velocity V 1 along an axis 74. The outside diameter D and thickness T of the tube as it leaves the extruder are shown in Fig. 7B at lines 7B-7B to be DI and TI. respectively.

Downstream of the extruder head 70 and typically spaced therefrom by approximately 30-70 mm is a calibrator 76, which assists in determining the outside diameter D and thickness T of the final tube. The outside diameter D2 and thickness T2 of the final tube as it leaves the calibrator 76 are also determined by the second linear velocity V2 at which the tube is drawn through the calibrator by drawing apparatus (not shown) downstream of the calibrator 76.

In the illustrated embodiment of Fig. 7A, it is seen that V2 < V I.

Thus. it may be appreciated that the cross-sectional area of the tube downstream of the calibrator 76, shown in Fig. 7C at lines 7C-7C, is greater than the cross-sectional area of the tube shown in Fig. 7B at lines 7B-7B.

In the illustrated embodiment of Fig. 7A, it is also seen that D2 > D I and T2=T1.

It is also noted that in the embodiment of Fig. 7A, the calibrator 76 is aligned along an axis 78 parallel to and offset downwardly with respect to axis 74.

Reference is now made to Figs. 8A, 8B and 8C, which are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with still another preferred embodiment of the present invention and of the tube at first and second stage of its manufacture, taken at lines 8B-8B and 8C-8C in Fig. 8A.

As seen in Fig. 8A, an extruder head 80, forming part of a conventional plastic extrusion machine (not shown), such as an extruder commercially available from NEXTROM of Lausanne, Switzerland, extrudes a seamless tube 82. The tube 82 leaves the extruder at a first linear velocity V I along an axis 84. The outside diameter D and thickness T of the tube as it leaves the extruder are shown in Fig. 8B at lines 8B-8B to be Dl and Tl, respectively.

Downstream of the extruder head 80 and typically spaced therefrom by approximately 30-70 mm is a calibrator 86, which assists in determining the outside diameter D and thickness T of the final tube. The outside diameter D2 and thickness T2 of the final tube as it leaves the calibrator 86 are also determined by the second linear velocity V2 at which the tube is drawn through the calibrator by drawing apparatus (not shown) downstream of the calibrator 86.

In the illustrated embodiment of Fig. 8A, it is seen that V2 < VI.

Thus. it may be appreciated that the cross-sectional area of the tube downstream of the calibrator 86, shown in Fig. 8C at lines 8C-8C, is greater than the cross-sectional area of the tube shown in Fig. 8B at lines 8B-8B.

In the illustrated embodiment of Fig. 8A, it is also seen that D2 > D 1 and T2>T1.

It is also noted that in the embodiment of Fig. 8A, the calibrator 86 is aligned along an axis 88 parallel to and offset downwardly with respect to axis 84.

Reference is now made to Figs. 9A, 9B and 9C, which are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with still another preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 9B-9B and 9C-9C in Fig. 9A.

As seen in Fig. 9A. an extruder head 90, forming part of a conventional plastic extrusion machine (not shown). such as an extruder commercially available from NEXTROM of Lausanne, Switzerland, extrudes a seamless tube 92. The tube 92 leaves the extruder at a first linear velocity V 1 along an axis 94. The outside diameter D and thickness T of the tube as it leaves the extruder are shown in Fig. 9B at lines 9B-9B to be Dl and T1, respectively.

Downstream of the extruder head 90 and typically spaced therefrom by approximately 30-70 mm is a calibrator 96, which assists in determining the outside diameter D and thickness T of the final tube. The outside diameter D2 and thickness T2 of the final tube as it leaves the calibrator 96 are also determined by the second linear velocity V2 at which the tube is drawn through the calibrator by drawing apparatus (not shown) downstream of the calibrator 96.

In the illustrated embodiment of Fig. 9A, it is seen that V2 < V I.

Thus. it may be appreciated that the cross-sectional area of the tube downstream of the calibrator 96, shown in Fig. 9C at lines 9C-9C. is greater than the cross-sectional area of the tube shown in Fig. 9B at lines 9B-9B.

In the illustrated embodiment of Fig. 9A, it is also seen that D2 < D1 and T2 > T1.

It is also noted that in the embodiment of Fig. 9A, the calibrator 96 is aligned along an axis 98, parallel to and offset downwardly with respect to axis 94.

Reference is now made to Figs. 10A, 1 OB and 10C, which are sectional illustrations respectively of apparatus and a method for extruding a plastic tube in accordance with still another preferred embodiment of the present invention and of the tube at first and second stages of its manufacture, taken at lines 1 OB-1 OB and l OC-l OC in Fig. 1 OA.

As seen in Fig. IOA. an extruder head 100, forming part of a conventional plastic extrusion machine (not shown), such as an extruder commercially available from NEXTROM of Lausanne, Switzerland. extrudes a seamless tube 102.

The tube 102 leaves the extruder at a first linear velocity V I along an axis 104. The outside diameter D and thickness T of the tube as it leaves the extruder are shown in Fig. I OB at lines lOB-l OB to be D1 and T1, respectively.

Downstream of the extruder head 100 and typically spaced therefrom by approximately 30-70 mm is a calibrator 106, which assists in determining the outside diameter D and thickness T of the final tube. The outside diameter D2 and thickness T2 of the final tube as it leaves the calibrator 106 are also determined by the second linear velocity V2 at which the tube is drawn through the calibrator by drawing apparatus (not shown) downstream of the calibrator 106.

In the illustrated embodiment of Fig. 10A, it is seen that V2 < V I.

Thus. it may be appreciated that the cross-sectional area of the tube downstream of the calibrator 106. shown in Fig. l OC at lines l OC-l OC, is greater than the cross-sectional area of the tube shown in Fig. 1 OB at lines 1 OB-1 OB.

In the illustrated embodiment of Fig. IOA, it is also seen that D2 > D1 and T2<T1.

It is also noted that in the embodiment of Fig. 10A, the calibrator 106 is aligned along an axis 108, which is parallel to and offset downwardly with respect to axis 104.

Reference is now made to Fig. 11 which illustrates, in a general sense, the manufacture of a drip irrigation tube in accordance with a preferred embodiment of the present invention. For the sake of conciseness. the method is illustrated in the context of the embodiment shown in Figs. 9A-9C of a method for manufacture of an extruded plastic tube, it being appreciated that the invention is not limited to that embodiment.

As shown in Fig. 11. drip irrigation inserts 200 are fed through the interior of an extrusion head 201 into the interior of a tube 202 being extruded therefrom. Various techniques exist for feeding and adhering drip irrigation inserts to the interior of a drip irrigation tube upon extrusion thereof and are described in one or more of the U. S. Patents listed hereinabove in the Background of the Invention, the disclosures of which are hereby incorporated by reference.

At present, it is believed to be preferable to feed the drip irrigation inserts along an axis 204 in parallel to the linear travel of the extruded plastic tube along an axis 206 such that the linear velocity of the drip irrigation insert 200 along axis 202 is equal to, slower or faster than the linear velocity of the drip irrigation tube 202 along axis 206 at the time of initial physical contact therebetween.

As shown in Fig. 11. insertion of the drip irrigation insert 200 into drip irrigation tube 202 takes place typically at a calibrator 208, which, as described above, assists in determining the outer diameter of the tube 202. As the tube 202 passes through the calibrator 208, the insert 200 becomes fully adhered thereto. The calibrator 208 is normally located within a water bath 210 maintained at negative pressure.

Downstream of the calibrator 208 the tube 202 passes through a further extent of the water bath 210 and then passes through a cooling water bath 212, which is maintained at atmospheric pressure.

Downstream of cooling water bath 212 the tube 202 is apertured at appropriate locations relative to the drip inserts 200 by a hole maker 214 and is engaged by one or more puller mechanism 216, one, but not all of which may be upstream of the hole maker 214. The tube is then rolled by a coiler 218.

It is a particular feature of the present invention that the linear velocity of the tube 200 at the calibrator 208 is less than the linear velocity of the tube 200 upstream thereof at the extrusion head 201. Thus, the cross sectional area of the tube 200 at the calibrator 208 is greater than that of the tube 200 at the extrusion head 201.

Reference is now made to Figs. 12A, 12B and 12C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 1 A, 1 B and 1 C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 12A-12C, a drip irrigation tube 250 is manufactured under conditions wherein the following parameters are operative: V 1. the linear speed of the tube 250, as it exits an extrusion head 252, is greater than V2, the linear speed of the tube 250 at a calibrator 254, downstream of the extrusion head ; D 1, the outer diameter of the tube 250, as it exits extrusion head 252, is generally equal to D2, the outer diameter of the tube 250 at calibrator 254, downstream of the extrusion head : TI, the thickness of the tube 250, as it exits extrusion head 252, is less than T2. the thickness of the tube 250 at calibrator 254, downstream of the extrusion head ; and V3, the insertion speed of a drip insert 256 into tube 250 is equal to V2 upon initial mutual engagement therebetween.

Turning to Fig. 12A. it is seen that a series of drip inserts 256 including a forward drip insert 260, are at rest at a time tl. Thereafter, as seen in Fig. 12B, the series of drip inserts 256, including forward drip insert 260, are caused to move forward at linear velocity V3, such that forward drip insert 260 moves at linear velocity V3 which is equal to the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 12C. following engagement of forward drip insert 260 with tube 250. the remaining drip inserts 256. including a next-in-line drip insert 262, remain at rest until such time as it is necessary to insert the next-in-line drip insert 262 in order to achieve a desired spacing of drip inserts along the tube 250.

Reference is now made to Figs. 13A. 13B and 13C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 1A, 1B and 1C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 13A-13C, a drip irrigation tube 350 is manufactured under conditions wherein the following parameters are operative: V 1. the linear speed of the tube 350, as it exits an extrusion head 352, is greater than V2. the linear speed of the tube 350 at a calibrator 354. downstream of the extrusion head ; D1, the outer diameter of the tube 350, as it exits extrusion head 352, is generally equal to D2. the outer diameter of the tube 350 at calibrator 354, downstream of the extrusion ; head : T1, the thickness of the tube 350, as it exits extrusion head 352, is less than T2, the thickness of the tube 350 at calibrator 354, downstream of the extrusion head ; and V3. the insertion speed of a drip insert 356 into tube 350 is greater than V2 upon initial mutual engagement therebetween.

Turning to Fig. 13A. it is seen that a series of drip inserts 356 including a forward drip insert 360, are at rest at a time tl. Thereafter, as seen in Fig. 13B, the series of drip inserts 356, including forward drip insert 360, are caused to move forward at linear velocity V3, such that forward drip insert 360 moves at linear velocity V3 which is greater than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 13C, following engagement of forward drip insert 360 with tube 350, the remaining drip inserts 356, including a next-in-line drip insert 362. remain at rest until such time as it is necessary to insert the next-in-line drip insert 362 in order to achieve a desired spacing of drip inserts along the tube 350.

Reference is now made to Figs. 14A, 14B and 14C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 1 A, 1 B and 1 C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 14A-14C, a drip irrigation tube 450 is manufactured under conditions wherein the following parameters are operative: VI. the linear speed of the tube 450, as it exits an extrusion head 452, is greater than V2. the linear speed of the tube 450 at a calibrator 454, downstream of the extrusion head : D1, the outer diameter of the tube 450, as it exits extrusion head 452, is generally equal to D2, the outer diameter of the tube 450 at calibrator 454, downstream of the extrusion head; T1, the thickness of the tube 450, as it exits extrusion head 452, is less than T2, the thickness of the tube 450 at calibrator 454, downstream of the extrusion head; and V3, the insertic n speed of a drip insert 456 into tube 450 is less than V2 upon initial mutual engagement therebetween.

Turning to Fig. 14A. it is seen that a series of drip inserts 456 including a forward drip insert 460, are at rest at a time tl. Thereafter, as seen in Fig. 14B, the series of drip inserts 456, including forward drip insert 460, are caused to move forward at linear velocity V3, such that forward drip insert 460 moves at linear velocity V3 which is less than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 14C. following engagement of forward drip insert 460 with tube 450, the remaining drip inserts 456, including a next-in-line drip insert 462, remain at rest until such time as it is necessary to insert the next-in-line drip insert 462 in order to achieve a desired spacing of drip inserts along the tube 450.

Reference is now made to Figs. 15A, 15B and 15C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 2A, 2B and 2C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 15A-15C, a drip irrigation tube 550 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 550, as it exits an extrusion head 552, is greater than V2, the linear speed of the tube 550 at a calibrator 554, downstream of the extrusion head : D1, the outer diameter of the tube 550, as it exits extrusion head 552, is smaller than D2. the outer diameter of the tube 550 at calibrator 554. downstream of the extrusion head : T1, the thickness of the tube 550, as it exits extrusion head 552, is generally equal to T2, the thickness of the tube 550 at calibrator 554. downstream of the extrusion head: and V3, the insertion speed of a drip insert 556 into tube 550 is equal to V2 upon initial mutual engagement therebetween.

Turning to Fig. 15A. it is seen that a series of drip inserts 556 including a forward drip insert 560, are at rest at a time tl. Thereafter, as seen in Fig. 15B, the series of drip inserts 556, including forward drip insert 560, are caused to move forward at linear velocity V3. such that forward drip insert 560 moves at linear velocity V3 which is equal to the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 15C. following engagement of forward drip insert 560 with tube 550. the remaining drip inserts 556. including a next-in-line drip insert 562, remain at rest until such time as it is necessary to insert the next-in-line drip insert 562 in order to achieve a desired spacing of drip inserts along the tube 550.

Reference is now made to Figs. 16A, 16B and 16C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 2A, 2B and 2C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 16A-16C, a drip irrigation tube 650 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 650, as it exits an extrusion head 652, is greater than V2. the linear speed of the tube 650 at a calibrator 654. downstream of the extrusion head: Dl, the outer diameter of the tube 650, as it exits extrusion head 652, is smaller than D2, the outer diameter of the tube 650 at calibrator 654. downstream of the extrusion head : Tl, the thickness of the tube 650, as it exits extrusion head 652, is generally equal to T2, the thickness of the tube 650 at calibrator 654, downstream of the extrusion head ; and V3. the insertion speed of a drip insert 656 into tube 650 is greater than V2 upon initial mutual engagement therebetween.

Turning to Fig. 16A, it is seen that a series of drip inserts 656 including a forward drip insert 660, are at rest at a time tl. Thereafter, as seen in Fig. 16B, the series of drip inserts 656. including forward drip insert 660. are caused to move forward at linear velocity V3, such that forward drip insert 660 moves at linear velocity V3 which is greater than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 16C. following engagement of forward drip insert 660 with tube 650, the remaining drip inserts 656, including a next-in-line drip insert 662. remain at rest until such time as it is necessary to insert the next-in-line drip insert 662 in order to achieve a desired spacing of drip inserts along the tube 650.

Reference is now made to Figs. 17A, 17B and 17C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 2A, 2B and 2C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 17A-17C, a drip irrigation tube 750 is manufactured under conditions wherein the following parameters are operative: V 1. the linear speed of the tube 750, as it exits an extrusion head 752, is greater than V2. the linear speed of the tube 750 at a calibrator 754. downstream of the extrusion head; D 1. the outer diameter of the tube 750, as it exits extrusion head 752, is smaller than D2, the outer diameter of the tube 750 at calibrator 754. downstream of the extrusion head; Tl. the thickr ess of the tube 750. as it exits extrusion head 752, is generally equal to T2, the thickness of the tube 750 at calibrator 754. downstream of the extrusion head ; and V3. the insertion speed of a drip insert 756 into tube 750 is less than V2 upon initial mutual engagement therebetween.

Turning to Fig. 17A, it is seen that a series of drip inserts 756 including a forward drip insert 760, are at rest at a time tl. Thereafter, as seen in Fig. 17B, the series of drip inserts 756. including forward drip insert 760. are caused to move forward at linear velocity V3. such that forward drip insert 760 moves at linear velocity V3 which is less than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 17C, following engagement of forward drip insert 760 with tube 750, the remaining drip inserts 756, including a next-in-line drip insert 762, remain at rest until such time as it is necessary to insert the next-in-line drip insert 762 in order to achieve a desired spacing of drip inserts along the tube 750.

Reference is now made to Figs. 18A, 18B and 18C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 3A. 3B and 3C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 18A-18C, a drip irrigation tube 850 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 850, as it exits an extrusion head 852, is greater than V2. the linear speed of the tube 850 at a calibrator 854. downstream of the extrusion head; DI, the outer diameter of the tube 850, as it exits extrusion head 852, is smaller than D2, the outer diameter of the tube 850 at calibrator 854, downstream of the extrusion head; TI. the thickness of the tube 850, as it exits extrusion head 852, is less than T2, the thickness of the tube 850 at calibrator 854. downstream of the extrusion head; and V3, the insertion speed of a drip insert 856 into tube 850 is equal to V2 upon initial mutual engagement therebetween.

Turning to Fig. 18A, it is seen that a series of drip inserts 856 including a forward drip insert 860, are at rest at a time tl. Thereafter, as seen in Fig. 18B, the series of drip inserts 856, including forward drip insert 860, are caused to move forward at linear velocity V3, such that forward drip insert 860 moves at linear velocity V3 which is equal to the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 18C, following engagement of forward drip insert 860 with tube 850, the remaining drip inserts 856, including a next-in-line drip insert 862, remain at rest until such time as it is necessary to insert the next-in-line drip insert 862 in order to achieve a desired spacing of drip inserts along the tube 850.

Reference is now made to Figs. 19A. 19B and 19C. which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. I A, I B and 1 C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 19A-19C, a drip irrigation tube 950 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 950, as it exits an extrusion head 952, is greater than V2, the linear speed of the tube 950 at a calibrator 954, downstream of the extrusion head; D 1. the outer diameter of the tube 950, as it exits extrusion head 952. is less than D2, the outer diameter of the tube 950 at calibrator 954. downstream of the extrusion head ; Tl, the thickness of the tube 950, as it exits extrusion head 952, is less than T2, the thickness of the tube 950 at calibrator 954, downstream of the extrusion head ; and V3, the insertion speed of a drip insert 956 into tube 950 is greater than V2 upon initial mutual engagement therebetween.

Turning to Fig. 19A. it is seen that a series of drip inserts 956 including a forward drip insert 960. are at rest at a time tl. Thereafter. as seen in Fig. 19B. the series of drip inserts 956, including forward drip insert 960. are caused to move forward at linear velocity V3. such that forward drip insert 960 moves at linear velocity V3 which is greater than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 19C, following engagement of forward drip insert 960 with tube 950, the remaining drip inserts 956, including a next-in-line drip insert 962. remain at rest until such time as it is necessary to insert the next-in-line drip insert 962 in order to achieve a desired spacing of drip inserts along the tube 950.

Reference is now made to Figs. 20A, 20B and 20C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 3A. 3B and 3C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 20A-20C, a drip irrigation tube 1050 is manufactured under conditions wherein the following parameters are operative: V I, the linear speed of the tube 1050, as it exits an extrusion head 1052, is greater than V2, the linear speed of the tube 1050 at a calibrator 1054, downstream of the extrusion head; D1. the outei diameter of the tube 1050, as it exits extrusion head 1052, is smaller than D2, the outer diameter of the tube 1050 at calibrator 1054, downstream of the extrusion head : T1, the thickness of the tube 1050, as it exits extrusion head 1052, is less than T2. the thickness of the tube 1050 at calibrator 1054, downstream of the extrusion head; and V3. the insertion speed of a drip insert 1056 into tube 1050 is less than V2 upon initial mutual engagement therebetween.

Turning to Fig. 20A, it is seen that a series of drip inserts 1056 including a forward drip insert 1060, are at rest at a time tl. Thereafter, as seen in Fig.

20B. the series of drip inserts 1056. including forward drip insert 1060. are caused to move forward at linear velocity V3. such that forward drip insert 1060 moves at linear velocity V3 which is less than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 20C, following engagement of forward drip insert 1060 with tube 1050, the remaining drip inserts 1056, including a next-in-line drip insert 1062. remain at rest until such time as it is necessary to insert the next-in-line drip insert 1062 in order to achieve a desired spacing of drip inserts along the tube 1050.

Reference is now made to Figs. 21 A, 21 B and 21 C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 4A, 4B and 4C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 21 A-21 C, a drip irrigation tube 1150 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 1150, as it exits an extrusion head 1152, is greater than V2, the linear speed of the tube 1150 at a calibrator 1154, downstream of the extrusion head ; D l. the outer diameter of the tube 1150, as it exits extrusion head 1152, is greater than D2, the outer diameter of the tube 1150 at calibrator 1154, downstream of the extrusion head; TI. the thickness of the tube 1150. as it exits extrusion head 1152, is less than T2. the thickness of the tube 1150 at calibrator 1154. downstream of the extrusion head ; and V3, the insertion speed of a drip insert 1156 into tube 1150 is equal to V2 upon initial mutual engagement therebetween.

Turning to Fig. 21 A, it is seen that a series of drip inserts 1156 including a forward drip insert 1160, are at rest at a time tl. Thereafter, as seen in Fig.

21 B, the series of drip inserts 1156. including forward drip insert 1160, are caused to move forward at linear velocity V3, such that forward drip insert 1160 moves at linear velocity V3 which is equal to the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 21C. following engagement of forward drip insert 1160 with tube 1150. the remaining drip inserts 1156. including a next-in-line drip insert 1162. remain at rest until such time as it is necessary to insert the next-in-line drip insert 1162 in order to achieve a desired spacing of drip inserts along the tube 1150.

Reference is now made to Figs. 22A, 22B and 22C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 4A, 4B and 4C, at three stages of carrying out of the method and wherein tne linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 22A-22C, a drip irrigation tube 1250 is manufactured under conditions wherein the following parameters are operative: VI. the linear speed of the tube 1250. as it exits an extrusion head 1252, is greater than V2, the linear speed of the tube 1250 at a calibrator 1254. downstream of the extrusion head ; D 1. the outer diameter of the tube 1250, as it exits extrusion head 1252, is greater than D2, the outer diameter of the tube 1250 at calibrator 1254, downstream of the extrusion head; TI, the thickness of the tube 1250, as it exits extrusion head 1252, is less than T2, the thickness of the tube 1250 at calibrator 1254, downstream of the extrusion head ; and V3. the insertion speed of a drip insert 1256 into tube 1250 is greater than V2 upon initial mutual engagement therebetween.

Turning to Fig. 22A. it is seen that a series of drip inserts 1256 including a forward drip insert 1260, are at rest at a time tl. Thereafter, as seen in Fig.

22B. the series of drip inserts 1256, including forward drip insert 1260, are caused to move forward at linear velocity V3, such that forward drip insert 1260 moves at linear velocity V3 which is greater than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 22C, following engagement of forward drip insert 1260 with tube 1250, the remaining drip inserts 1256, including a next-in-line drip insert 1262. remain at rest until such time as it is necessary to insert the next-in-line drip insert 1262 in order to achieve a desired spacing of drip inserts along the tube 1250.

Reference is now made to Figs. 23A. 23B and 23C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 4A, 4B and 4C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 23A-23C, a drip irrigation tube 1350 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 1350, as it exits an extrusion head 1352, is greater than V2, the linear çpeed of the tube 1350 at a calibrator 1354, downstream of the extrusion head : D1. the outer diameter of the tube 1350, as it exits extrusion head 1352, is greater than D2, the outer diameter of the tube 1350 at calibrator 1354, downstream of the extrusion head: T1. the thickness of the tube 1350, as it exits extrusion head 1352, is less than T2, the thickness of the tube 1350 at calibrator 1354, downstream of the extrusion head; and V3, the insertion speed of a drip insert 1356 into tube 1350 is less than V2 upon initial mutual engagement therebetween.

Turning to Fig. 23A. it is seen that a series of drip inserts 1356 including a forward drip insert 1360. are at rest at a time tl. Thereafter, as seen in Fig.

23B, the series of drip inserts 1356, including forward drip insert 1360, are caused to move forward at linear velocity V3, such that forward drip insert 1360 moves at linear velocity V3 which is less than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 23C, following engagement of forward drip insert 1360 with tube 1350, the remaining drip inserts 1356, including a next-in-line drip insert 1362, remain at rest until such time as it is necessary to insert the next-in-line drip insert 1362 in order to achieve a desired spacing of drip inserts along the tube 1350.

Reference is now made to Figs. 24A, 24B and 24C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. SA, 5B and 5C, at three stages of carry ins out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 24A-24C. a drip irrigation tube 1450 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 1450. as it exits an extrusion head 1452, is greater than V2. the linear speed of the tube 1450 at a calibrator 1454, downstream of the extrusion head; D 1. the outer diameter of the tube 1450. as it exits extrusion head 1452. is less than D2. the outer diameter of the tube 1450 at calibrator 1454. downstream of the extrusion head: T1, the thickness of the tube 1450, as it exits extrusion head 1452, is greater than T2, the thickness of the tube 1450 at calibrator 1454, downstream of the extrusion head; and V3, the insertion speed of a drip insert 1456 into tube 1450 is equal to V2 upon initial mutual engagement therebetween.

Turning to Fig. 24A, it is seen that a series of drip inserts 1456 including a forward drip insert 1460, are at rest at a time tl. Thereafter, as seen in Fig.

24B. the series of drip inserts 1456. including forward drip insert 1460, are caused to move forward at linear velocity V3. such that forward drip insert 1460 moves at linear velocity V3 which is equal to the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 24C. following engagement of forward drip insert 1460 with tube 1450, the remaining drip inserts 1456, including a next-in-line drip insert 1462. remain at rest until such time as it is necessary to insert the next-in-line drip insert 1462 in order to achieve a desired spacing of drip inserts along the tube 1450.

Reference is now made to Figs. 25A, 25B and 25C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. SA, 5B and 5C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 25A-25C, a drip irrigation tube 1550 is manufactured under conditions wherein the following parameters are operative: VI. the linear speed of the tube 1550, as it exits an extrusion head 1552, is greater than V2, the linear speed of the tube 1550 at a calibrator 1554, downstream of the extrusion head; D 1, the outer diameter of the tube 1550, as it exits extrusion head 1552, is less than D2. the outer diameter of the tube 1550 at calibrator 1554, downstream of the extrusion head; Tl, the thickness of the tube 1550, as it exits extrusion head 1552, is greater than T2, the thickness of the tube 1550 at calibrator 1554, downstream of the extrusion head : and V3. the insertion speed of a drip insert 1556 into tube 1550 is greater than V2 upon initial mutual engagement therebetween.

Turning to Fig. 25A. it is seen that a series of drip inserts 1556 including a forward drip insert 1560, are at rest at a time tl. Thereafter, as seen in Fig.

25B, the series of drip inserts 1556, including forward drip insert 1560, are caused to move forward at linear velocity V3, such that forward drip insert 1560 moves at linear velocity V3 which is greater than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 25C. following engagement of forward drip insert 1560 with tube 1550. the remaining drip inserts 1556. including a next-in-line drip insert 1562. remain at rest until such time as it is necessary to insert the next-in-line drip insert 1562 in order to achieve a desired spacing of drip inserts along the tube 1550.

Reference is now made to Figs. 26A, 26B and 26C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 5A, 5B and 5C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween.

As seen in Fia ;. 26A-26C, a drip irrigation tube 1650 is manufactured under conditions wherein the following parameters are operative: V 1. the linear speed of the tube 1650, as it exits an extrusion head 1652, is greater than V2. the linear speed of the tube 1650 at a calibrator 1654, downstream of the extrusion head ; D1, the outer diameter of the tube 1650, as it exits extrusion head 1652, is less than D2, the outer diameter of the tube 1650 at calibrator 1654, downstream of the extrusion head; T1, the thickness of the tube 1650, as it exits extrusion head 1652, is greater than T2, the thickness of the tube 1650 at calibrator 1654, downstream of the extrusion head; and V3, the insertion speed of a drip insert 1656 into tube 1650 is less than V2 upon initial mutual engagement therebetween.

Turning to Fig. 26A. it is seen that a series of drip inserts 1656 including a forward drip insert 1660, are at rest at a time tl. Thereafter, as seen in Fig.

26B, the series of drip inserts 1656, including forward drip insert 1660, are caused to move forward at linear velocity V3, such that forward drip insert 1660 moves at linear velocity V3 which is less than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 26C. following engagement of forward drip insert 1660 with tube 1650, the remaining drip inserts 1656, including a next-in-line drip insert 1662. remain at rest until such time as it is necessary to insert the next-in-line drip insert 1662 in order to achieve a desired spacing of drip inserts along the tube 1650.

Reference is now made to Figs. 27A, 27B and 27C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 6A, 6B and 6C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 27A-97C a drip irrigation tube 1750 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 1750, as it exits an extrusion head 1752, is greater than V2, the linear speed of the tube 1750 at a calibrator 1754, downstream of the extrusion head ; DI. the outer diameter of the tube 1750. as it exits extrusion head 1752, is generally equal to D2, the outer diameter of the tube 1750 at calibrator 1754. downstream of the extrusion head ; T1, the thickness of the tube 1750, as it exits extrusion head 1752, is less than T2. the thickness of the tube 1750 at calibrator 1754, downstream of the extrusion head; and V3. the insertion speed of a drip insert 1756 into tube 1750 is equal to V2 upon initial mutual engagement therebetween.

Turning to Fig. 27A, it is seen that a series of drip inserts 1756 including a forward drip insert 1760. are at rest at a time tl. Thereafter. as seen in Fig.

27B. the series of drip inserts 1756. including forward drip insert 1760. are caused to move forward at linear velocity V3. such that forward drip insert 1760 moves at linear velocity V3 which is equal to the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 27C. following engagement of forward drip insert 1760 with tube 1750, the remaining drip inserts 1756, including a next-in-line drip insert 1762, remain at rest until such time as it is necessary to insert the next-in-line drip insert 1762 in order to achieve a desired spacing of drip inserts along the tube 1750.

Reference is now made to Figs. 28A, 28B and 28C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 6A, 6B and 6C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 28A-28C, a drip irrigation tube 350 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 1850, as it exits an extrusion head 1852, is greater than V2. the linear speed of the tube 1850 at a calibrator 1854, downstream of the extrusion head; D1, the outer diameter of the tube 1850, as it exits extrusion head 1852, is generally equal to D2. the outer diameter of the tube 1850 at calibrator 1854, downstream of the extrusion head ; Tl, the thickness of the tube 1850, as it exits extrusion head 1852, is less than T2. the thickness of the tube 1850 at calibrator 1854, downstream of the extrusion head ; and V3. the insertion speed of a drip insert 1856 into tube 1850 is greater than V2 upon initial mutual engagement therebetween.

Turning to Fig. 28A, it is seen that a series of drip inserts 1856 including a forward drip insert 1860. are at rest at a time tl. Thereafter, as seen in Fig.

28B, the series of drip inserts 1856, including forward drip insert 1860, are caused to move forward at linear velocity V3, such that forward drip insert 1860 moves at linear velocity V3 which is greater than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 28C. following engagement of forward drip insert 1860 with tube 1850, the remaining drip inserts 1856, including a next-in-line drip insert 1862, remain at rest until such time as it is necessary to insert the next-in-line drip insert 1862 in order to achieve a desired spacing of drip inserts along the tube 1850.

Reference is now made to Figs. 29A, 29B and 29C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodirrent of Figs. 6A, 6B and 6C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 29A-29C, a drip irrigation tube 1950 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 1950, as it exits an extrusion head 1952, is greater than V2, the linear speed of the tube 1950 at a calibrator 1954, downstream of the extrusion ; D 1, the outer diameter of the tube 1950, as it exits extrusion head 1952, is generally equal to D2, the outer diameter of the tube 1950 at calibrator 1954, downstream of the extrusion head; T1, the thickness of the tube 1950, as it exits extrusion head 1952, is less than T2. the thickness of the tube 1950 at calibrator 1954, downstream of the extrusion head; and V3, the insertion speed of a drip insert 1956 into tube 1950 is less than V2 upon initial mutual engagement therebetween.

Turning to Fig. 29A, it is seen that a series of drip inserts 1956 including a forward drip insert 1960, are at rest at a time tl. Thereafter, as seen in Fig.

29B, the series of drip inserts 1956, including forward drip insert 1960, are caused to move forward at linear velocity V3, such that forward drip insert 1960 moves at linear velocity V3 which is less than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 29C, following engagement of forward drip insert 1960 with tube 1950, the remaining drip inserts 1956, including a next-in-line drip insert 1962. remain at rest until such time as it is necessary to insert the next-in-line drip insert 1962 in order to achieve a desired spacing of drip inserts along the tube 1950.

Reference is now made to Figs. 30A, 30B and 30C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 7A. 7B and 7C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 30A-30C, a drip irrigation tube 2050 is manufactured under conditions wherein the following parameters are operative: V 1. the linear speed of the tube 2050, as it exits an extrusion head 2052, is greater than V2. the linear speed of the tube 2050 at a calibrator 2054, downstream of the extrusion head : Dl. the outer diameter of the tube 2050, as it exits extrusion head 2052. is smaller than D2, the outer diameter of the tube 2050 at calibrator 2054, downstream of the extrusion head; Tl, the thickness of the tube 2050, as it exits extrusion head 2052, is generally equal to T2. the thickness of the tube 2050 at calibrator 2054 downstream of the extrusion head ; and V3. the insertion speed of a drip insert 2056 into tube 2050 is equal to V2 upon initial mutual engagement therebetween.

Turning to Fig. 30A, it is seen that a series of drip inserts 2056 including a forward drip insert 2060, are at rest at a time tl. Thereafter, as seen in Fig.

30B, the series of drip inserts 2056. including forward drip insert 2060, are caused to move forward at linear velocity V3. such that forward drip insert 2060 moves at linear velocity V3 which is equal to the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 30C following engagement of forward drip insert 2060 with tube 2050. the remaining drip inserts 2056, including a next-in-line drip insert 2062, remain at rest until such time as it is necessary to insert the next-in-line drip insert 2062 in order to achieve a desired spacing of drip inserts along the tube 2050.

Reference is now made to Figs. 31 A, 31 B and 31 C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 7A, 7B and 7C. at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 31 A-31C, a drip irrigation tube 2150 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 2150, as it exits an extrusion head 2152, is greater than V2. the linear speed of the tube 2150 at a calibrator 2154, downstream of the extrusion head: D 1, the outer diameter of the tube 2150, as it exits extrusion head 2152, is smaller than D2, the outer diameter of the tube 2150 at calibrator 2154, downstream of the extrusion head; Tl, the thickness of the tube 2150, as it exits extrusion head 2152, is generally equal to T2. the thickness of the tube 2150 at calibrator 2154. downstream of the extrusion head ; and V3, the insertion speed of a drip insert 2156 into tube 2150 is greater than V2 upon initial mutual engagement therebetween.

Turning to Fig. 31 A. it is seen that a series of drip inserts 2156 including a forward drip insert 2160, are at rest at a time t 1. Thereafter, as seen in Fig.

31 B, the series series drip inserts inserts 2156. including forward drip insert 2160, are caused to move forward at linear velocity V3, such that forward drip insert 2160 moves at linear velocity V3 which is greater than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 31 C, following engagement of forward drip insert 2160 with tube 2150, the remaining drip inserts 2156, including a next-in-line drip insert 2162, remain at rest until such time as it is necessary to insert the next-in-line drip insert 2162 in order to achieve a desired spacing of drip inserts along the tube 2150.

Reference is now made to Figs. 32A. 32B and 32C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 7A, 7B and 7C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 32A-32C, a drip irrigation tube 2250 is manufactured under conditions wherein the following parameters are operative: V I, the linear speed of the tube 2250, as it exits an extrusion head 2252, is greater than V2, the linear speed of the tube 2250 at a calibrator 2254, downstream of the extrusion head; D 1, the outer diameter of the tube 2250, as it exits extrusion head 2252. is smaller than D2, the outer diameter of the tube 2250 at calibrator 2254, downstream of the extrusion head; T1, the thickness of the tube 2250, as it exits extrusion head 2252, is generally equal to T2. the thickness of the tube 2250 at calibrator 2254. downstream of the extrusion head ; and V3, the insertion speed of a drip insert 2256 into tube 2250 is less than V2 upon initial mutual engagement therebetween.

Turning to Fig. 32A. it is seen that a series of drip inserts 2256 including a forward drip insert 2260. are at rest at a time tl. Thereafter, as seen in Fig.

32B. the series of drip inserts 2256. including forward drip insert 2260, are caused to move forward at linear velocity V3, such that forward drip insert 2260 moves at linear velocity V3 which is less than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 32C, following engagement of forward drip insert 2260 with tube 2250. the remaining drip inserts 2256, including a next-in-line drip insert 2262. remain at rest until such time as it is necessary to insert the next-in-line drip insert 2262 in order to achieve a desired spacing of drip insel. along the tube 2250.

Reference is now made to Figs. 33A, 33B and 33C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 8A, 8B and 8C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 33A-33C, a drip irrigation tube 2350 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 2350, as it exits an extrusion head 2352, is greater than V2. the linear speed of the tube 2350 at a calibrator 2354, downstream of the extrusion head : D1, the outer diameter of the tube 2350, as it exits extrusion head 2352, is smaller than D2, the outer diameter of the tube 2350 at calibrator 2354, downstream of the extrusion head ; Tl. the thickness of the tube 2350. as it exits extrusion head 2352, is less than T2. the thickness of the tube 2350 at calibrator 2354. downstream of the extrusion head; and V3, the insertion speed of a drip insert 2356 into tube 2350 is equal to V2 upon initial mutual engagement therebetween.

Turning to Fig. 33A. it is seen that a series of drip inserts 2356 including a forward drip insert 2360, are at rest at a time tl. Thereafter. as seen in Fig.

33B, the series of drip inserts 2356, including forward drip insert 2360, are caused to move forward at linear velocity V3, such that forward drip insert 2360 moves at linear velocity V3 which is equal to the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 33C, following engagement of forward drip insert 2360 with tube 2350, the remaining drip inserts 2356, including a next-in-line drip insert 2362, remain at rest until such time as it is necessary to insert the next-in-line drip insert 2362 in order to achieve a desired spacing of drip inserts along the tube 2350.

Reference is now made to Figs. 34A, 34B and 34C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 8A, 8B and 8C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 34A-34C, a drip irrigation tube 2450 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 2450, as it exits an extrusion head 2452, is greater than V2, the linear speed of the tube 2450 at a calibrator 2454, downstream of the extrusion head; D1, the outer diameter of the tube 2450, as it exits extrusion head 2452, is less than D2, the outer diameter of the tube 2450 at calibrator 2454, downstream of the extrusion head: T1, the thickness of the tube 2450, as it exits extrusion head 2452, is less than T2. the thickness of the tube 2450 at calibrator 2454, downstream of the extrusion head : and V3, the insertion speed of a drip insert 2456 into tube 2450 is greater than V2 upon initial mutual engagement therebetween.

Turning to Fig. 34A, it is seen that a series of drip inserts 2456 including a forward drip insert 2460, are at rest at a time tl. Thereafter. as seen in Fig.

34B. the series of drip inserts 2456, including forward drip insert 2460, are caused to move forward at linear velocity V3, such that forward drip insert 2460 moves at linear velocity V3 which is greater than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 34C, foliowing engagement of forward drip insert 2460 with tube 2450, the remaining drip inserts 2456, including a next-in-line drip insert 2462. remain at rest until such time as it is necessary to insert the next-in-line drip insert 2462 in order to achieve a desired spacing of drip inserts along the tube 2450.

Reference is now made to Figs. 35A, 35B and 35C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 8A, 8B and 8C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 35A-35C, a drip irrigation tube 2550 is manufactured under conditions wherein the following parameters are operative: V1. the linear speed of the tube 2550, as it exits an extrusion head 2552, is greater than V2, the linear speed of the tube 2550 at a calibrator 2554, downstream of the extrusion head; D1, the outer diameter of the tube 2550, as it exits extrusion head 2552, is smaller than D2, the outer diameter of the tube 2550 at calibrator 2554, downstream of the extrusion head; Tl, the thickness of the tube 2550, as it exits extrusion head 2552, is less than T2, the thickness of the tube 2550 at calibrator 2554, downstream of the extrusion head; and V3. the insertion speed of a drip insert 2556 into tube 2550 is less than V2 upon initial mutual engagement therebetween.

Turning to Fig. 35A. it is seen that a series of drip inserts 2556 including a forward drip insert 2560. are at rest at a time tl. Thereafter. as seen in Fig.

35B. the series of drip inserts 2556, including forward drip insert 2560, are caused to move forward at linear velocity V3, such that forward drip insert 2560 moves at linear velocity V3 which is less than the linear velocity V2 of the tube at the location at which initial mucual engagement of the insert with the tube takes place.

As shown in Fig. 35C, following engagement of forward drip insert 2560 with tube 2550. the remaining drip inserts 2556, including a next-in-line drip insert 2562. remain at rest until such time as it is necessary to insert the next-in-line drip insert 2562 in order to achieve a desired spacing of drip inserts along the tube 2550.

Reference is now made to Figs. 36A, 36B and 36C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 9A, 9B and 9C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 36A-36C, a drip irrigation tube 2650 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 2650, as it exits an extrusion head 2652, is greater than V2, the linear speed of the tube 2650 at a calibrator 2654, downstream of the extrusion head; D1. the outer diameter of the tube 2650. as it exits extrusion head 2652. is greater than D2, the outer diameter of the tube 2650 at calibrator 2654. downstream of the extrusion head : Tl, the thickness of the tube 2650, as it exits extrusion head 2652, is less than T2, the thickness of the tube 2650 at calibrator 2654, downstream of the extrusion head; and V3. the insertion speed of a drip insert 2656 into tube 2650 is equal to V2 upon initial mutual engagement therebetween.

Turning to Fig. 36A. it is seen that a series of drip inserts 2656 including a forward drip insert 2660, are at rest at a time tl. Thereafter, as seen in Fig.

36B, the series of drip inserts 2656, including forward drip insert 2660, are caused to move forward at linear velocity V3, such that forward drip insert 2660 moves at linear velocity V3 which is equal to the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 36C, following engagement of forward drip insert 2660 with tube 2650, the remaining drip inserts 2656, including a next-in-line drip insert 2662, remain at rest until such time as it is necessary to insert the next-in-line drip insert 2662 in order to achieve a desired spacing of drip inserts along the tube 2650.

Reference is now made to Figs. 37A, 37B and 37C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 9A, 9B and 9C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 37A-37C. a drip irrigation tube 2750 is manufactured under conditions wherein the following parameters are operative: V I, the linear speed of the tube 2750, as it exits an extrusion head 2752, is greater than V2, the linear speed of the tube 2750 at a calibrator 2754, downstream of the extrusion head; D1, the outer diameter of the tube 2750, as it exits extrusion head 2752. is greater than D2, the outer diameter of the tube 2750 at calibrator 2754, downstream of the extrusion head : Tl, the thickness of the tube 2750, as it exits extrusion head 2752, is less than T2, the thickness of the tube 2750 at calibrator 2754, downstream of the extrusion head; and V3, the insertion speed of a drip insert 2756 into tube 2750 is greater than V2 upon initial mutual engagement therebetween.

Turning to Fig. 37A. it is seen that a series of drip inserts 2756 including a forward drip insert 2760, are at rest at a time tl. Thereafter, as seen in Fig.

37B, the series of drip insert, 2756, including forward drip insert 2760, are caused to move forward at linear velocity V3. such that forward drip insert 2760 moves at linear velocity V3 which is greater than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 37C. following engagement of forward drip insert 2760 with tube 2750, the remaining drip inserts 2756, including a next-in-line drip insert 2762, remain at rest until such time as it is necessary to insert the next-in-line drip insert 2762 in order to achieve a desired spacing of drip inserts along the tube 2750.

Reference is now made to Figs. 38A, 38B and 38C, which are simplified sectional illustration of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 9A, 9B and 9C, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 38A-38C. a drip irrigation tube 2850 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 2850, as it exits an extrusion head 2852, is greater than V2, the linear speed of the tube 2850 at a calibrator 2854, downstream of the extrusion head ; Dl, the outer diameter of the tube 2850, as it exits extrusion head 2852, is greater than D2, the outer diameter of the tube 2850 at calibrator 2854, downstream of the extrusion ; T1. the thickness of the tube 2850, as it exits extrusion head 2852, is less than T2. the thickness of the tube 2850 at calibrator 2854, downstream of the extrusion head ; and V3. the insertion speed of a drip insert 2856 into tube 2850 is less than V2 upon initial mutual engagement therebetween.

Turning to Fig. 38A, it is seen that a series of drip inserts 2856 including a forward drip insert 2860, are at rest at a time tl. Thereafter, as seen in Fig.

38B, the series of drip inserts 2856, including forward drip inset 2860, are caused to move forward at linear velocity V3, such that forward drip insert 2860 moves at linear velocity V3 which is less than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 38C. following engagement of forward drip insert 2860 with tube 2850. the remaining drip inserts 2856, including a next-in-line drip insert 2862. remain at rest until such time as it is necessary to insert the next-in-line drip insert 2862 in order to achieve a desired spacing of drip inserts along the tube 2850.

Reference is now made to Figs. 39A, 39B and 39C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 10A, l OB and l OC, at three stages of carrying out of the method and wherein the linear speed of a drip insert is generally equal to that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 39A-39C, a drip irrigation tube 2950 is manufactured under conditions wherein the following parameters are operative: V 1, the linear speed of the tube 2950, as it exits an extrusion head 2952, is greater than V2. the linear speed of the tube 2950 at a calibrator 2954, downstream of the extrusion head : D I. the outer diameter of the tube 2950. as it exits extrusion head 2952. is less than D2, the outer diameter of the tube 2950 at calibrator 2954, downstream of the extrusion head; T1, the thickness of the tube 2950, as it exits extrusion head 2952, is greater than T2, the thickness of the tube 2950 at calibrator 2954, downstream of the extrusion head; and V3. the insertion speed of a drip insert 2956 into tube 2950 is equal to V2 upon initial mutual engagement therebetween.

Turning to Fig. 39A, it is seen that a series of drip inserts 2956 including a forward drip insert 2960, are at rest at a time tl. Thereafter, as seen in Fig.

39B, the series of drip inserts 2956, including forward drip insert 2960, are caused to move forward at linear velocity V3, such that forward drip insert 2960 moves at linear velocity V3 which is equal to the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 39C. following engagement of forward drip insert 2960 with tube 2950, the remaining drip inserts 2956, including a next-in-line drip insert 2962, remain at rest until such time as it is necessary to insert the next-in-line drip insert 2962 in order to achieve a desired spacing of drip inserts along the tube 2950.

Reference is now made to Figs. 40A, 40B and 40C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 10A. I OB and I OC, at three stages of carrying out of the method and wherein the linear speed of a drip insert is greater than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 40A-40C, a drip irrigation tube 3050 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 3050, as it exits an extrusion head 3052, is greater than V2, the linear speed of the tube 3050 at a calibrator 3054, downstream of the extrusion head : D 1. the outer diameter of the tube 3050. as it exits extrusion head 3052 is less than D2. the outer diameter of the tube 3050 at calibrator 3054, downstream of the extrusion head; T1, the thickness of the tube 3050, as it exits extrusion head 3052, is greater than T2, the thickness of the tube 3050 at calibrator 3054, downstream of the extrusion head; and V3. the insertion speed of a drip insert 3056 into tube 3050 is greater than V2 upon initial mutual engagement therebetween.

Turning to Fig. 40A, it is seen that a series of drip inserts 3056 including a forward drip inser 3060. are at rest at a time tl. Thereafter, as seen in Fig.

40B. the series of drip inserts ; 056, including forward drip insert 3060, are caused to move forward at linear velocity V3, such that forward drip insert 3060 moves at linear velocity V3 which is greater than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 40C. following engagement of forward drip insert 3060 with tube 3050, the remaining drip inserts 3056, including a next-in-line drip insert 3062, remain at rest until such time as it is necessary to insert the next-in-line drip insert 3062 in order to achieve a desired spacing of drip inserts along the tube 3050.

Reference is now made to Figs. 41A, 41B and 41C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 10A, l OB and l OC, at three stages of carrying out of the method and wherein the linear speed of a drip insert is less than that of the tube upon initial mutual engagement therebetween.

As seen in Figs. 41 A-41 C. a drip irrigation tube 3150 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 3150, as it exits an extrusion head 3152, is greater than V2, the linear speed of the tube 3150 at a calibrator 3154, downstream of the extrusion head ; D1, the outer diameter of the tube 3150, as it exits extrusion head 3152, is less than D2. the outer diameter of the tube 3150 at calibrator 3154, downstream of the extrusion head; T1, the thickness of the tube 3150. as it exits extrusion head 3152, is greater than T2. the thickness of the tube 3150 at calibrator 3154, downstream of the extrusion head ; and V3, the insertion speed of a drip insert 3156 into tube 3150 is less than V2 upon initial mutual engagement therebetween.

Turning to Fig. 41 A, it is seen that a series of drip inserts 3156 including a forward drip insert 3160, are at rest at a time tl. Thereafter, as seen in Fig.

41B, the series of drip inserts 3156, including forward drip insert 3160, are caused to move forward at linear velocity V3, such that forward drip insert 3160 moves at linear velocity V3 which is less than the linear velocity V2 of the tube at the location at which initial mutual engagement of the insert with the tube takes place.

As shown in Fig. 41C. following engagement of forward drip insert 3160 with tube 3150, the remaining drip inserts 3156, including a next-in-line drip insert 3162. remain at rest until such time as it is necessary to insert the next-in-line drip insert 3162 in order to achieve a desired spacing of drip inserts along the tube 3150.

Reference is now made to Figs. 42A, 42B and 42C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 1 A. 1 B and 1C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

As seen in Figs. 42A-42C, a drip irrigation tube 3250 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 3250, as it exits an extrusion head 3252, is greater than V2. the linear speed of the tube 3250 at a calibrator 3254, downstream of the extrusion head: D1. the outer diameter of the tube 3250, as it exits extrusion head 3252, is generally equal to D2, the outer diameter of the tube 3250 at calibrator 3254, downstream the extrusion head; T1, the thickness of the tube 3250, as it exits extrusion head 3252, is less than T2, the thickness of the tube 3250 at calibrator 3254, downstream of the extrusion head; and V3, the insertion speed of a drip insert 3256 into tube 3250 is equal to V2 multiplied by L/d. where L is the length of the drip insert 3256 and d is the desired spacing between centers of respective sequentially inserted drip inserts 3256 in tube 3250.

Turning to Fig. 42A, it is seen that a series of drip inserts 3256 including a forward drip insert 3260. are in continuous linear motion at a generally uniform velocity V3 at all relevant times, here indicated by times tl, t2 and t3. As seen in Fig. 42A, at time tl, the forward edge of a forward drip insert 3260 is seen approaching engagement with tube 3250. Thereafter, as seen in Fig. 42B, as the series of drip inserts 3256, including forward drip insert 3260 continue to move forward at linear velocity V3. forward drip insert 3260 moves into initial engagement with the tube 3250 at velocity V3.

As shown in Fig. 42C, during and following engagement of forward drip insert 3260 with tube 3250. the remaining drip inserts 3256, including a next-in-line drip insert 3262. continue their forward motion at velocity V3. which is determined by the ratio of L and d, in order to achieve a desired spacing of drip inserts along the tube 3250. As seen in Fig. 42C, upon engagement of forward drip insert 3260 with tube 3250, forward drip insert 3260 moves forward at speed V2. which is substantially greater than V3 and thus becomes separated from the remaining drip inserts of series 3256.

Reference is now made to Figs. 43A, 43B and 43C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 2A, 2B and 2C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

As seen in Figs. 43A-43C, a drip irrigation tube 3350 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 3350, as it exits an extrusion head 3352, is greater than V2, the linear speed of the tube 3350 at a calibrator 3354, downstream of the extrusion head; D1, the outer diameter of the tube 3350, as it exits extrusion head 3352, is smaller than D2, the outer diameter of the tube 3350 at calibrator 3354, downstream of the extrusion 1ead ; Tl. the thickness of the tube 3350. as it exits extrusion head 3352, is equal to T2. the thickness of the tube 3350 at calibrator 3354. downstream of the extrusion head: and V3, the insertion speed of a drip insert 3356 into tube 3350 is equal to V2 multiplied by L/d, where L is the length of the drip insert 3356 and d is the desired spacing between centers of respective sequentially inserted drip inserts 3356 in tube 3350.

Turning to Fig. 43A, it is seen that a series of drip inserts 3356 including a forward drip insert 3360, are in continuous linear motion at a generally uniform velocity V3 at all relevant times, here indicated by times tl. t2 and t3. As seen in Fig. 43A, at time tl, the forward edge of a forward drip insert 3360 is seen approaching engagement with tube 3350. Thereafter, as seen in Fig. 43B, as the series of drip inserts 3356. including forward drip insert 3360 continue to move forward at linear velocity V3. forward drip insert 3360 moves into initial engagement with the tube 3350 at velocity V3.

As shown in Fig. 4') C. during and following engagement of forward drip insert 3360 with tube 3350, the remaining drip inserts 3356, including a next-in-line drip insert 3362, continue their forward motion at velocity V3, which is determined by the ratio of L and d, in order to achieve a desired spacing of drip inserts along the tube 3350. As seen in Fig. 43C, upon engagement of forward drip insert 3360 with tube 3350, forward drip insert 3360 moves forward at speed V2. which is substantially greater than V3 and thus becomes separated from the remaining drip inserts of series 3356.

Reference is now made to Figs. 44A, 44B and 44C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 3A. 3B and 3C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

As seen in Figs. 44A-44C, a drip irrigation tube 3450 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 3450, as it exits an extrusion head 3452, is greater than V2, the linear speed of the tube 3450 at a calibrator 454, downstream of the extrusion head; D1. the outer diameter of the tube 3450, as it exits extrusion head 3452, is smaller than D2. the outer diameter of the tube 3450 at calibrator 3454, downstream of the extrusion head : T1, the thickness of the tube 3450, as it exits extrusion head 3452, is less than T2. the thickness of the tube 3450 at calibrator 3454, downstream of the extrusion head; and V3, the insertion speed of a drip insert 3456 into tube 3450 is equal to V2 multiplied by L/d, where L is the length of the drip insert 3456 and d is the desired spacing between centers of respective sequentially inserted drip inserts 3456 in tube 3450.

Turning to Fig. 44A. it is seen that a series of drip inserts 3456 including a forward drip insert 3460. are in continuous linear motion at a generally uniform velocity V3 at all relevant times, here indicated by times tl, t2 and t3. As seen in Fig. 44A, at time tl, the forward edge of a forward drip insert 3460 is seen approaching engagement with tube 3450. Thereafter, as seen in Fig. 44B, as the series of drip inserts 3456, including forward drip insert 3460 continue to move forward at linear velocity V3, forward drip insert 3460 moves into initial engagement with the tube 3450 at velocity V3.

As shown in Fig. 44C, during and following engagement of forward drip insert 3460 with tube 3450, the remaining drip inserts 3456, including a next-in-line drip insert 3462, continue their forward motion at velocity V3, which is determined by the ratio of L and d, in order to achieve a desired spacing of drip inserts along the tube 3450. As seen in Fig. 44C, upon engagement of forward drip insert 3460 with tube 3450, forward drip insert 3460 moves forward at speed V2, which is substantially greater than V3 and thus becomes separated from the remaining drip inserts of series 3456.

Reference is now made to Figs. 45A, 45B and 45C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 4A, 4B and 4C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

As seen in Figs. 45A-45C, a drip irrigation tube 3550 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 3550, as it exits an extrusion head 3552, is greater than V2. the linear speed of the tube 3550 at a calibrator 3554. downstream of the extrusion head; D1, the outer diameter of the tube 3550, as it exits extrusion head 3552, is greater than D2, the outer diameter of the tube 3550 at calibrator 3554, downstream of the extrusion head; T1, the thickness of the tube 3550, as it exits extrusion head 3552, is less than T2, the thickness of the tube 3550 at calibrator 3554, downstream of the extrusion head; and V3, the insertion speed of a drip insert 3556 into tube 3550 is equal to V2 multiplied by L/d, where L is the length of the drip insert 3556 and d is the desired spacing between centers of respective sequentially inserted drip inserts 3556 in tube 3550.

Turning to Fig. 45A, it is seen that a series of drip inserts 3556 including a forward drip insert 3560, are in continuous linear motion at a generally uniform velocity V3 at all relevant times, here indicated by times tl, t2 and t3. As seen in Fig. 45A, at time tl, the forward edge of a forward drip insert 3560 is seen approaching engagement with tube 3550. Thereafter, as seen in Fig. 45B. as the series of drip inserts 3556, including forward drip insert 3560 continue to move forward at linear velocity V3, forward drip insert 3560 moves into initial engagement with the tube 3550 at velocity V3.

As shown in Fig. 45C. during and following engagement of forward drip insert 3560 with tube 3550, the remaining drip inserts 3556, including a next-in-line drip insert 3562, continue their forward motion at velocity V3, which is determined by the ratio of L and d, in order to achieve a desired spacing of drip inserts along the tube 3550. As seen in Fig. 45C, upon engagement of forward drip insert 3560 with tube 3550, forward drip insert 3560 moves forward at speed V2, which is substantially greater than V3 and thus becomes separated from the remaining drip inserts of series 3556.

Reference is now made to Figs. 46A, 46B and 46C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. SA, 5B and 5C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

As seen in Figs. 46A-46C, a drip irrigation tube 3650 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 3650, as it exits an extrusion head 3652, is greater than V2, the linear speed of the tube 3650 at a calibrator 3654, downstream of the extrusion head; Dl. the outer diameter of the tube 3650, as it exits extrusion head 3652. is smaller than D2, the outer diameter of the tube 3650 at calibrator 3654, downstream of the extrusion head: TI. the thickness of the tube 3650. as it exits extrusion head 3652, is greater than T2, the thickness of the tube 3650 at calibrator 3654, downstream of the extrusion head; and V3, the insertion speed of a drip insert 3656 into tube 3650 is equal to V2 multiplied by L/d, where L is the length of the drip insert 3656 and d is the desired spacing between centers of respective sequentially inserted drip inserts 3656 in tube 3650.

Turning to Fig. 46A. it is seen that a series of drip inserts 3656 including a forward drip insert 3660. are in continuous linear motion at a generally uniform velocity V3 at all relevant times. here indicated by times tl. t2 and t3. As seen in Fig. 46A, at time tl. the forward edge of a forward drip insert 3660 is seen approaching engagement with tube 3650. Thereafter. as seen in Fig. 46B. as the series of drip inserts 3656, including forward drip insert 3660 continue to move forward at linear velocity V3, forward drip insert 3660 moves into initial engagement with the tube 3650 at velocity V3.

As shown in Fig. 46C. during and following engagement of forward drip insert 3660 with tube 3650, the remaining drip inserts 3656, including a next-in-line drip insert 3662, continue their forward motion at velocity V3, which is determined by the ratio of L and d, in order to achieve a desired spacing of drip inserts along the tube 3650. As seen in Fig. 46C, upon engagement of forward drip insert 3660 with tube 3650, forward drip insert 3660 moves forward at speed V2. which is substantially greater than V3 and thus becomes separated from the remaining drip inserts of series 3656.

Reference is now made to Figs. 47A, 47B and 47C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 6A, 63 and 6C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

As seen in Figs. 47A-47C, a drip irrigation tube 3750 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 3750, as it exits an extrusion head 3752, is greater than V2, the linear speed of the tube 3750 at a calibrator 3754, downstream of the extrusion head ; Dl, the outer diameter of the tube 3750, as it exits extrusion head 3752, is generally equal to D2, the outer diameter of the tube 3750 at calibrator 3754, downstream of the extrusion head ; T1, the thickness of the tube 3750, as it exits extrusion head 3752, is less than T2. the thickness of the tube 3750 at calibrator 3754, downstream of the extrusion head; and V3. the insertion speed of a drip insert 3756 into tube 3750 is equal to V2 multiplied by L/d, where L is the length of the drip insert 3756 and d is the desired spacing between centers of respective sequentially inserted drip inserts 3756 in tube 3750.

Turning to Fig. 47A it is seen that a series of drip inserts 3756 including a forward drip insert 3760. are in continuous linear motion at a generally uniform velocity V3 at all relevant times, here indicated by times tl. t2 and t3. As seen in Fig. 47A, at time tl, the forward edge of a forward drip insert 3760 is seen approaching engagement with tube 3750. Thereafter, as seen in Fig. 47B, as the series of drip inserts 3756, including forward drip insert 3760 continue to move forward at linear velocity V3, forward drip insert 3760 moves into initial engagement with the tube 3750 at velocity V3.

As shown in Fig. 47C. during and following engagement of forward drip insert 3760 with tube 3750, the remaining drip inserts 3756, including a next-in-line drip insert 3762. continue their forward motion at velocity V3. which is determined by the ratio of L and d. in order to achieve a desired spacing of drip inserts along the tube 3750. As seen in Fig. 47C, upon engagement of forward drip insert 3760 with tube 3750, forward drip insert 3760 moves forward at speed V2. which is substantially greater than V3 and thus becomes separated from the remaining drip inserts of series 3756.

Reference is n (w made to Figs. 48A, 48B and 48C, which are simplified sectional illustratior s of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 7A, 7B and 7C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

As seen in Figs. 48A-48C, a drip irrigation tube 3850 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 3850, as it exits an extrusion head 3852, is greater than V2, the linear speed of the tube 3850 at a calibrator 3854. downstream of the extrusion head; D1, the outer diameter of the tube 3850, as it exits extrusion head 3852, is smaller than D2, the outer diameter of the tube 3850 at calibrator 3854, downstream of the extrusion head; T1, the thickness of the tube 3850, as it exits extrusion head 3852, is generally equal to T2. the thickness of the tube 3850 at calibrator 3854. downstream of the extrusion head : and V3, the insertion speed of a drip insert 3856 into tube 3850 is equal to V2 multiplied by L/d, where L is the length of the drip insert 3856 and d is the desired spacing between centers of respective sequentially inserted drip inserts 3856 in tube 3850.

Turning to Fig. 48A, it is seen that a series of drip inserts 3856 including a forward drip insert 3860, are in continuous linear motion at a generally uniform velocity V3 at all relevant times, here indicated by times tl. t2 and t3. As seen in Fig. 48A. at time tl, the forward edge of a forward drip insert 3860 is seen approaching engagement with tube 3850. Thereafter, as seen in Fig. 48B. as the series of drip inserts 3856. including forward drip insert 3860 continue to move forward at linear velocity V3, forward drip insert 3860 moves into initial engagement with the tube 3850 at velocity V3.

As shown in Fig. 48C, during and following engagement of forward drip insert 3860 with tube 3850, the remaining drip inserts 3856, including a next-in-line drip insert 3862, continue their forward motion at velocity V3, which is determined by the ratio of L and d, in order to achieve a desired spacing of drip inserts along the tube 3850. As seen in Fig. 48C, upon engagement of forward drip insert 3860 with tube 3850, forward drip insert 3860 moves forward at speed V2. which is substantially greater than V3 and thus becomes separated from the remaining drip inserts of series 3856.

Reference is now made to Figs. 49A. 49B and 49C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 8A, 8B and 8C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

As seen in Figs. 49A-49C, a drip irrigation tube 3950 is manufactured under conditions wherein the following parameters are operative: VI, the linear speed of the tube 3950, as it exits an extrusion head 3952, is greater than V2. the linear speed of the tube 3950 at a calibrator 3954, downstream of the extrusion head ; DI, the outer diameter of the tube 3950, as it exits extrusion head 3952. is smaller than D2, the outer diameter of the tube 3950 at calibrator 3954, downstream of the extrusion head : Tl, the thickness of the tube 3950, as it exits extrusion head 3952, is less than T2. the thickness of the tube 3950 at calibrator 3954, downstream of the extrusion head ; and V3, the insertion speed of a drip insert 3956 into tube 3950 is equal to V2 multiplied by L/d. where L is the length of the drip insert 3956 and d is the desired spacing between centers of respective sequentially inserted drip inserts 3956 in tube 3950.

Turning to Fig. 49A. it is seen that a series of drip inserts 3956 including a forward drip insert 3960. are in continuous linear motion at a generally uniform velocity V3 at all relevant times, here indicated by times tl, t2 and t3. As seen in Fig. 49A, at time tl, the forward edge of a forward drip insert 3960 is seen approaching engagement with tube 3950. Thereafter, as seen in Fig. 49B, as the series of drip inserts 3956, including forward drip insert 3960 continue to move forward at linear velocity V3. forward drip insert 3960 moves into initial engagement with the tube 3950 at velocity V3.

As shown in Fig. 49C. during and following engagement of forward drip insert 3960 with tube 3950, the remaining drip inserts 3956, including a next-in-line drip insert 3962. continue their forward motion at velocity V3, which is determined by the ratio of L and d, in order to achieve a desired spacing of drip inserts along the tube 3950. As seen in Fig. 49C, upon engagement of forward drip insert 3960 with tube 3950, forward drip insert 3960 moves forward at speed V2, which is substantially greater than V3 and thus becomes separated from the remaining drip inserts of series 3956.

Reference is now made to Figs. 50A, SOB and SOC, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. 9A, 9B and 9C, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

As seen in Figs. SOA-SOC, a drip irrigation tube 4050 is manufactured under conditions wherein the following parameters are operative: V I, the linear speed of the tube 4050. as it exits an extrusion head 4052, is greater than V2. the linear speed of the tube 4050 at a calibrator 4054. downstream of the extrusion head ; D 1, the outer diameter of the tube 4050, as it exits extrusion head 4052. is greater than D2, the outer diameter of the tube 4050 at calibrator 4054, downstream of the extrusion head; T1. the thickness of the tube 4050, as it exits extrusion head 4052, is less than T2, the thickness of the tube 4050 at calibrator 4054, downstream of the extrusion head ; and V3. the insertion speed of a drip insert 4056 into tube 4050 is equal to V2 multiplied by L/d, where L is the length of the drip insert 4056 and d is the desired spacing between centers of respective sequentially inserted drip inserts 4056 in tube 4 Turning to Fig. 50A, it is seen that a series of drip inserts 4056 including a forward drip insert 4060, are in continuous linear motion at a generally uniform velocity V3 at all relevant times, here indicated by times tl, t2 and t3. As seen in Fig. 50A, at time tl, the forward edge of a forward drip insert 4060 is seen approaching engagement with tube 4050. Thereafter, as seen in Fig. SOB, as the series of drip inserts 4056. including forward drip insert 4060 continue to move forward at linear velocity V3, forward drip insert 4060 moves into initial engagement with the tube 4050 at velocity V3.

As shown in Fig. SOC. during and following engagement of forward drip insert 4060 with tube 4050, the remaining drip inserts 4056, including a next-in-line drip insert 4062, continue their forward motion at velocity V3, which is determined by the ratio of L and d, in order to achieve a desired spacing of drip inserts along the tube 4050. As seen in Fig. SOC, upon engagement of forward drip insert 4060 with tube 4050, forward drip insert 4060 moves forward at speed V2, which is substantially greater than V3 and thus becomes separated from the remaining drip inserts of series 4056.

Reference is now made to Figs. 51 A, 51 B and 5 1 C, which are simplified sectional illustrations of apparatus and a method for producing a drip irrigation tube corresponding to the embodiment of Figs. l0A, l OB and l OC, at three stages of carrying out of the method and wherein the linear feeding speed of a drip insert is generally constant.

As seen in Figs. 51A-51C, a drip irrigation tube 4150 is manufactured under conditions wherein tlle following parameters are operative: VI, the linear speed of the tube 4150, as it exits an extrusion head 4152, is greater than V2, the linear speed of the tube 4150 at a calibrator 4154, downstream of the extrusion head.

Dl, the outer diameter of the tube 4150, as it exits extrusion head 4152, is smaller than D2, the outer diameter of the tube 4150 at calibrator 4154, downstream of the extrusion head; T1. the thickness of the tube 4150, as it exits extrusion head 4152, is greater than T2. the thickness of the tube 4150 at calibrator 4154, downstream of the extrusion head; and V3, the insertion speed of a drip insert 4156 into tube 4150 is equal to V2 multiplied by L/d. where L is the length of the drip insert 4156 and d is the desired spacing between centers of respective sequentially inserted drip inserts 4156 in tube 4150.

Turning to Fig. 51 A, it is seen that a series of drip inserts 4156 including a forward drip insert 4160, are in continuous linear motion at a generally uniform velocity V3 at all relevant times, here indicated by times tl. t2 and t3. As seen in Fig. 51A, at time tl. the forward edge of a forward drip insert 4160 is seen approaching engagement with tube 4150. Thereafter, as seen in Fig. 51B, as the series of drip inserts 4156. including forward drip insert 4160 continue to move forward at linear velocity V3. forward drip insert 4160 moves into initial engagement with the tube 4150 at velocity V3.

As shown in Fig. 51 C, during and following engagement of forward drip insert 4160 with tube 4150, the remaining drip inserts 4156, including a next-in-line drip insert 4162, continue their forward motion at velocity V3, which is determined by the ratio of L and d, in order to achieve a desired spacing of drip inserts along the tube 4150. As seen in Fig. 5 1 C, upon engagement of forward drip insert 4160 with tube 4150, forward drip insert 4160 moves forward at speed V2. which is substantially greater than V3 and thus becomes separated from the remaining drip inserts of series 4156.

It will be appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes various features as well as combinations and subcombinations of the features described hereinabove and in