TECHNICAL FIELD

This invention relates to an incision unit and an incision method, in particular for making a weakness in a strip of plastic material. This invention also relates to a packaging apparatus, in particular for making a sealed single-dose break-open package.

BACKGROUND ART

Sealed single-dose packages comprise a sheet of semi-rigid plastic material and a sheet of flexible plastic material, which is superposed on and sealed to the sheet of semi-rigid plastic material to form a sealed pocket which contains a dose of a product.

There are single-dose packages in which, to facilitate supplying of the product, the sheet of semi-rigid plastic material centrally has a weakened zone which guides controlled breaking of the sheet of semi-rigid plastic material in such a way as to cause the formation of a product outlet opening through the sheet of semi-rigid plastic material. In other words, in use to open the sealed package a user must grasp the sealed package with the fingers of one hand and bend the sealed package into a “V” shape until the sheet of semi-rigid plastic material breaks at the weakened zone.

In order to make the package, use is known of an apparatus which comprises a reel for feeding a web of semi-rigid material and a reel for feeding a web of flexible material, an incision unit for making an incision in the sheet of semi-rigid plastic material, a unit for forming the package and a cutting unit for separating the filled package. Several devices are known for making the incision in the sheet of semi-rigid plastic material.

Document W02008038074 describes an incision unit which has two parallel facing plates, movable relative to each other to engage with the strip of semi-rigid material, which support knives. Each plate is pushed towards the other by means of a respective linear actuator, in such a way as to retain the strip of semi-rigid material and to make an incision on each side of it.

There is also a known device which comprises two facing plates, in which a first plate is provided with incision tools. A strip of semi-rigid plastic material is interposed between the two plates. The first plate is movable towards the second plate up to a drawn near position so as to make a deformation in the strip of semi rigid plastic material. The movable plate is driven by three pneumatic cylinders which operate simultaneously. This type of movement does not allow control of the depth of the incision, which could be insufficient or too great.

Moreover, the cylinders are associated with a single plate on which multiple incision tools are positioned. Associated with the incision tool supporting plate there are micrometers, one for each incision tool, for adjusting their travel. Therefore, adjustment of the travel is difficult and the incision depth may vary from one zone to another of the strip of semi-rigid plastic material.

DESCRIPTION OF THE INVENTION

The aim of this invention is to make in a strip of material a deformation or incision which has a precise depth.

According to this invention, an incision unit is provided having the features defined in claim 1.

According to another aspect of this invention, a packaging apparatus is provided having the features defined in claim 11.

According to a further aspect of this invention, an incision method comprises the features defined in claim 12.

BRIEF DESCRIPTION OF THE DRAWINGS

This invention will now be described with reference to the accompanying drawings, which illustrate several example, non-limiting embodiments of it, in which:

• Figure 1 illustrates a perspective top view of a sealed single-dose package;

• Figure 2 illustrates a perspective view of the sheet of semi-rigid plastic material of a sealed single-dose package;

• Figure 3 illustrates a perspective view of an apparatus for making a sealed single-dose package in a preferred embodiment of this invention;

• Figure 4 illustrates a side view of an embodiment of the incision unit of the apparatus of Figure 3;

• Figure 5 illustrates a perspective view of an embodiment of the incision unit of the apparatus of Figure 3;

• Figure 6 illustrates a perspective view of a detail of the slide of the incision unit in a preferred embodiment.

PREFERRED EMBODIMENTS OF THE INVENTION

In Figure 1, the numeral 1 denotes in its entirety a sealed single-dose package. The sealed single-dose package 1 comprises a sheet 2 of semi-rigid plastic material and a sheet 3 of flexible plastic material, which is superposed on and sealed to the sheet 2 of semi-rigid plastic material to form (between the two sheets 2 and 3) a sealed pocket 4 which contains a dose of a product 5.

The first sheet 2 of semi-rigid plastic material is stiffer than the second sheet 3 of flexible plastic material.

Preferably the first sheet 2 of semi-rigid plastic material and/or the second sheet 3 of flexible plastic material is substantially flat.

Advantageously the sheet 2 of semi-rigid plastic material has a weakened zone, which guides controlled breaking of the sheet 2 of semi-rigid plastic material in such a way as to cause the formation of a product 5 outlet opening through the sheet 2 of semi-rigid plastic material. In other words, in use to open the sealed single-dose package 1 a user must grasp the sealed single-dose package 1 with the fingers of one hand and bend the sealed single-dose package 1 into a “V” shape until the sheet 2 of semi-rigid plastic material breaks at the weakened zone. When the sheet 2 of semi-rigid plastic material is broken at the weakened zone, the product 5 can be made to come out of the sealed single-dose package 1 in a simple and hygienic way.

The weakened zone preferably comprises at least one non-through incision 6 (that is to say, which does not pass completely through the sheet 2 of semi-rigid plastic material) which is made in a surface of the sheet 2 of semi-rigid plastic material. The incision 6 is advantageously positioned in a central zone of the sheet 2 of semi-rigid plastic material.

The incision 6 may have various shapes. For example, Figure 2 shows a curved incision 6.

Preferably, the incision 6 is made on the inside 21 of the sheet 2 of semi-rigid plastic material, that is to say, on the inside of the pocket 4.

In one embodiment not illustrated, the package has two lateral weaknesses. Preferably, the package 1 comprises a first substantially straight weakening incision, positioned at one edge of the first sheet 2 and a second substantially straight weakening incision, positioned at the opposite edge. The substantially straight incisions are positioned laterally and at a distance relative to the incision 6 made in the central zone. The substantially straight incisions are non-through incisions, that is to say, they do not pass completely through the sheet 2 of semi rigid plastic material. Preferably the substantially straight incisions are made on the outside 22 of the sheet 2 of semi-rigid plastic material.

In Figure 3, the numeral 7 denotes a packaging apparatus for making a sealed single-dose break-open package 1 in a preferred embodiment of this invention.

The apparatus 7 comprises a first feed unit 8 for feeding a first strip 9 of semi rigid plastic material and a second feed unit 10 for feeding a second strip 11 of flexible plastic material. The apparatus 7 comprises an incision unit 12 for making a deformation in the strip 9 of semi-rigid material. The apparatus 7 comprises a forming unit 13 in which at least one portion of the strip 9 of semi-rigid material is superposed on and joined to a corresponding portion of the strip 11 of flexible material to form and fill the pocket 4.

The apparatus 7 also comprises a cutting unit 14 after the forming unit 13, in which the individual packages are separated from the sealed excess material (waste).

The strip 9 of semi-rigid plastic material, picked up from the feed unit 8, for example from a reel, passes into the incision unit 12, in which the strip 9 of semi rigid plastic material is deformed or shaped.

Figure 4 shows a preferred embodiment of the incision unit 12.

According to the invention, the incision unit 12 comprises at least one plate 15, at least one slide 16 movable between a position moved away from the plate 15 and a position drawn near to the plate 15, at least one incision tool 17 associated with the slide 16, and at least one forward movement device 18 for moving the slide 16 towards the plate 15.

The plate 15 is preferably fixed, and is substantially a support for the strip 9 of semi-rigid plastic material.

Advantageously, one end of the incision tool 17 has the shape of the incision which must be made in the sheet 2 of semi-rigid material.

The slide 16 is shifted towards the plate 15 in such a way that the free end of the incision tool 17 moves forward until it is at a preset distance from the supporting plate 15 to make a deformation in the strip 9 of semi-rigid plastic material.

In this way the deformation is made with constant depth, which is precisely controlled.

Advantageously, the forward movement device 18 comprises at least one electric motor. In particular, the electric motor is a brushless motor, preferably with controllable speed, position and torque.

Advantageously, the forward movement device 18 comprises a screw actuator. Preferably the screw 181 has a micrometric pitch (Figures 5 and 6).

The slide 16 is slidable on a supporting guide 19. In the embodiment illustrated in Figure 6 the supporting guide 19 comprises two lateral tracks 191. The ends of the tracks 191 are fixed to corresponding plates 193. Each plate 193 has a hole for insertion of the screw 181.

In the embodiment illustrated in Figures 5 and 6, the slide 16 comprises a base 23 which is slidable on the guide 19 and a supporting body 24 for the incision tool 17. Advantageously, the supporting body 24 is fixed on the base 23 by means of position screws and/or pins.

The base 23 of the slide 16 has a hole 25 into which the screw 181 is inserted. By means of rotation of the screw 181 the slide 16 moves on the tracks 191, towards or away from the plate 15.

In one advantageous embodiment, the incision unit 12 comprises an electronic control device for the forward movement of the slide 16, preferably a micrometric control device. In particular, it is possible to control the revolutions of the motor in order to obtain a minimum forward movement of the slide which is 0.002 mm for each motor revolution. In a preferred embodiment, for each motor revolution the slide 16 moves forward 1 mm.

In a preferred embodiment, the control device is integrated in the motor, in such a way as to vary the stroke of the slide 16 based on requirements.

In this way it is possible to adjust the incision depth with extreme precision.

As illustrated in Figures 4 and 5, the body 24 of the slide 16 has one end 26 projecting towards the plate 15, into which end the incision tool 17 is inserted and fixed. In this way it is possible to replace the incision tool 17 depending on the shape of the incision to be made. The projecting end 26 allows forward movement of the slide 16 for any shape of the package, without interfering with other parts of the machine.

In the embodiment illustrated, the projecting end 26 comprises a lower portion 27 and an upper portion 28. The lower portion 27 has a recess 29 in such a way as to create a support for the incision tool 17. The upper portion 28 comprises a flat element 30 which rests and is fixed, for example by means of screws, on the lower portion 27 in such a way as to lock the incision tool 27 to the body 24 of the slide 16.

In the packaging apparatus 7 illustrated, the deformation in the central zone is advantageously only made on the side of the strip 9 which will form the inner surface 21 of the semi-rigid sheet 2.

In an embodiment not illustrated the packaging apparatus comprises a second incision unit for making two substantially straight incisions in the strip of semi rigid plastic material. The straight incisions are preferably made on the opposite side of the strip to that in which the central zone incision is made.

The incision method according to this invention comprises the steps of positioning a strip 9 of material, in particular plastic, between at least one fixed plate 15 and at least one slide 16 provided with at least one incision tool 17; moving the slide 16 forward towards the fixed plate 15 until it reaches a predetermined drawn near distance; keeping the slide 16 in the drawn near position for a predetermined time, in such a way that the incision tool 17 makes at least one weakness in the strip 9; moving the slide 16 away from the fixed plate 15 until it reaches a moved away position.

The method advantageously comprises an initial zero setting step. The zero setting step consists of making the slide move forward with constant speed with torque control until it reaches the fixed plate. When the plate is reached, the torque control detects an obstruction and saves the position as zero. That zero setting step is preferably performed at the start of a production cycle and/or in a planned way after n cycles. The zero setting step can be started manually by an operator.

During an incision cycle, in the incision unit 12 the motion of the strip 9 of semi rigid plastic material is intermittent, that is to say, the strip 9 is moved forward a predetermined extent and then stopped. Then, when the plastic material is positioned in the correct position the motor operates the slide 16 which moves forward the predetermined extent, creating the incision and returns backwards to the wait position to subsequently allow the new incision cycle. In an advantageous embodiment the forward movement of the slide 16 occurs with a feedback check on the position of the motor. Its speed and acceleration are constantly checked. The position drawn near to the fixed plate 15 for making the incision (incision position) is determined by the zero value and by a parameter set by the operator.

The slide 16 remains in that incision position for a time set by the operator. This time value is determined by the physical properties of the plastic material used for production and can be modified by the operator.

After incision of the material, the slide 16 moves to the position moved away from the fixed plate 15.

That moved away position is advantageously a position outside the working area, while waiting for the material to move forward again and for the cycle to start again.

According to a preferred embodiment, during the incision cycle, the resisting torque detected by the motor is monitored. This torque is compared with a theoretically identified reference torque. If the torque values detected by the motor do not match, an inconsistency is detected and the production cycle is interrupted. The fault is reported in such a way that the operator verifies that the unit is mechanically operating and effective.

After the incision has been made, the strip 9 of semi-rigid material passes into the forming unit 13, where it is joined to the strip 11 of flexible material arriving from the second feed unit 10, for example from a second reel.

The forming unit 13 comprises a sealing station 130 and a filling station 140.

The sealing station 130 advantageously comprises at least one pair of rollers 31, 33 and at least one rotary sealer 32. In particular, at least one first pair of hot rollers 31 is positioned in the upper part of the sealing station 130 and makes a longitudinal seal in the two superposed strips 9, 11. The rotary sealer 32 is positioned below the pair of hot rollers 31 and makes a transversal seal to close the filled packages and at the same time, during the rotation, to make the closed base of the packages which are still to be filled. Positioned in the lower part of the sealing station 130 there is a second pair of cold rollers 33 for keeping the superposed and sealed strips 9, 11 tensioned and conveying them towards the next cutting unit 14.

The filling station 140 comprises a tank which is preferably pressurised, containing a product; a product supplying device; and at least one feed duct having a first end connected to the tank and a second end connected to the supplying device.

Advantageously, the filling station 140 comprises a control unit for controlling the dosing time and pressure connected to the tank and to the supplying device.

In the cutting unit 14 after the forming unit 13 the individual packages are separated from the sealed excess material (waste).

The individual packages are advantageously sent into a container positioned below the cutting unit 14.

In a preferred embodiment, the packaging apparatus 7 simultaneously makes a plurality of sealed single-dose break-open packages.

In that embodiment, the incision unit 12 comprises a plurality of slides 16, each associated with a respective incision tool 17.

Advantageously, a corresponding motor is associated with each slide 16.

There is preferably a single fixed plate 15. This allows, as far as possible, the elimination of any dimensional errors due to production of the part. In the packaging apparatus 7, the strip 9 of semi-rigid plastic material descends vertically between the plate 15 and the slides 16, which move simultaneously to make a plurality of incisions in the strip 9. The slides 16 are preferably positioned at the same height to make incisions which are spaced apart along the width of the strip.

The micrometric control is centralised, in such a way that the stroke is the same for all of the slides 16 and the incisions all have the same depth.

In the sealing station 130, the longitudinal and transversal seals are then made in such a way as to define individual packages in which the incisions are present. Compared with prior art apparatuses, the incision unit according to this invention allows precise control of the incision depth. The incision tools are not fixed on a single plate which moves by means of a pneumatic actuator, instead they are associated with individual slides which perform a continuous movement towards and away, allowing micrometric control of the stroke.

If multiple incisions are made, there is no need to adjust each individual incision tool by means of micrometers, since the micrometric control is already inserted in the motor and is centralised. Therefore, it is enough to fix the incision tool to the slide, whose stroke will be electronically controlled with extreme precision.