FIELD

[0001] The invention relates to manufacture of spirally wound polyolefm pipes and vessels.

BACKGROUND

[0002] Spirally wound polyolefm pipes are used in various infrastructure systems for distribution of water, drainage, energy, electricity or any other purpose where a flow channels or protection form environment are needed. Similar uses can be found in industry and other fields of technology. Spirally wound pipe may have a very large diameter and the strength of the pipe can be adjusted to large range of purposes. The manufacturing method is suitable for making vessels as well as pipes. Spirally wound pipes or vessels are manufactured by winding a plastic profile around a mandrel as a spiral. When the profile is wound on the mandrel, the edge of the incoming profile is fused on the previous round of the profile in order to form a

[0003] The fusing of the rounds of the profile together is commonly done by welding or otherwise heating the surfaces that are joined together. Alternatively the profile that is wound on the mandrel may be extruded or heated hot enough to provide fusion of the edges of the profile together.

[0004] After end of production a piece of pipe remains on the mandrel. The length of the remaining pipe varies between 1 to 2m depending on diameter of the pipe that is manufactured and winder type used. This remaining part is cut up and handled as scrap. This so called stop scrap increases the consumption of the material and work needed for producing a certain length of pipe and increases manufacturing costs. Increased costs and loss of manufacturing time make short production runs unfeasible, which reduces flexibility of the manufacture. These factors are underlined in manufacture of prefabricates for vessels. As the length of a prefabricate may be typically 2 - 5 m, loss of 1 to 2 meters of manufactured material induces high costs. This is further emphasized by a fact that manufacture of spirally wound pipes or vessels is rather time consuming, whereby the productive input used is markable.

SUMMARY OF THE INVENTION

[0005] The invention is defined by the features of the independent claims. Some specific embodiments are defined in the dependent claims.

[0006] According to a first aspect of the present invention, there is provided a method for ejecting a spirally wound polyolefm pipe section from a mandrel, wherein the mandrel has a longitudinal axis around of which it is rotated and a cylindrical outer surface around which the profile forming the pipe section is wound. The method comprises steps of cutting the profile that is wound on the mandrel to form an end of the pipe section, pushing at least one ejector element against the end of the pipe section, holding the at least one ejector element stationary in the direction of longitudinal axis of the mandrel, and rotating the mandrel and pipe section in the same direction as the profile is wound on the mandrel. [0007] According to a second aspect of the present invention, there is provided an apparatus for ejecting a spirally wound polyolefm pipe section from a mandrel, wherein the mandrel has a longitudinal axis around of which it can be rotated and a cylindrical outer surface around which the profile forming the pipe section can be wound. The apparatus comprises at least one ejector element and a pusher for transferring the at least one ejector element parallel to the longitudinal axis of the mandrel and holding the ejector element on a set position and an actuator for rotating the mandrel..

[0008] According to a third aspect of the invention the ejector element is an ejector roller that has a rotation axis crosswise to the longitudinal axis of the mandrel.

[0009] According to a fourth aspect of the invention there is provided a monitoring system for detecting contact of the at least one ejector element with the end of the pipe section that is on the mandrel.

[0010] According to a fifth aspect of the invention, there is provided a mandrel, at least one rail running parallel to the longitudinal axis of the mandrel, a carriage mounted on the at least one rail and transferrable along at least one rail, a linear actuator for transferring the carriage and an ejector element mounted on the carrier by a transfer actuator for adjusting the position of the ejector element in radial direction of the mandrel.

[0011] According to a sixth aspect of the present invention, the invention comprises detecting passing of the at least one ejector roller past the cut end of the profile and pushing the at least one ejector roller in the direction of the longitudinal axis of the mandrel so that the ejector roller is set against the end of the pipe section.

[0012] According to a seventh aspect of the present invention, passing of the at least one ejector roller past the cut end of the profile is detected by monitoring the rotating movement of the ejector roller. [0013] According to a eighth aspect of the present invention, the contact of the at least one ejector roller with the end of the pipe section is detected by monitoring the power needed to move the ejector roller in direction of the longitudinal axis of the mandrel.

BRIEF DESCRIPTION OF THE DRAWINGS [0014] FIGURE 1 illustrates a winder for producing a spirally wound pipe and an ejector in accordance with at least some embodiments of the present invention;

[0015] FIGURE 2 is a front view of the winder of the FIGURE 1 ;

[0016] FIGURE 3 is a side view of the winder of the FIGURE 1 ;

[0017] FIGURE 4 illustrates a detail of FIGURE 1 ; [0018] FIGURE 5 illustrates the winder of FIGURE 1 in a second setup;

[0019] FIGURE 6 illustrates the winder of FIGURE 1 in a third setup;

[0020] FIGURE 7 illustrates an example apparatus of FIGURE 1 capable of supporting at least some embodiments of the present invention and in a fourth setup;

[0021] FIGURE 8 illustrates a second example apparatus capable of supporting at least some of the embodiments of the present invention in a side view

[0022] FIGURE 9 illustrates the apparatus of FIGURE 8 in an end view. [0023] FIGURE 10 illustrates the apparatus of FIGURE 8 in a top view.

EMBODIMENTS

[0024] DEFINITIONS [0025] In the present context, the term "pipe section" is used to describe any object made of spirally wound polyolefm profile, for example pipes, vessels, prefabricates and parts thereof.

[0026] The longitudinal central axis of the mandrel is the axis around which the cylindrical mandrel can be rotated, i.e. central axis of the cylinder forming the mandrel. [0027] One example of an apparatus for manufacturing spirally wound pipes is described in US 6939422. This document may be used as reference if more detailed description of the manufacturing method as such is needed.

[0028] The invention relates to manufacture of spirally wound polyolefm pipes, in particular ejecting the remaining part of pipe away from mandrel after end of production of one size of a pipe. After the end of production run of a defined size of a pipe, a piece of pipe remains on the mandrel. The length of the remaining piece of pipe varies, for example, between 1 to 2m depending on pipe diameter and winder type. This remaining part is cut up and handled as scrap. Since pipe sizes are usually quite large, the amount of recycled material is high. This so called stop scrap can be reduced by the embodiments of the invention. Reduced amount of scrap will also make shorter production runs more feasible. Increased feasibility of shorter production runs can lead to shorter lead time for certain prefabricated products, such as prefabricates for vessels. Customers of manufacturers will have a clear economic benefit. Environmental gains are also achieved through reduced scrap by the various embodiments of the invention. [0029] In some embodiments of the invention, the ejector comprises two identical units located on the winder star and working on opposite sides of the pipe. The ejector units are arranged to push the manufactured pipe off the mandrel until the pipe is clear from the mandrel. Main parts of each unit are contact roller, screw jack, jack motor/gearbox and adjusting/support frame. The functional principle is that the winder rotation (rotation of the mandrel and the pipe section on it) of the spirally wound pipe works as a screw when rotating and pushing itself forward by the force against the ejector rollers. The ejector rollers are driven forward by the screw jack after passing the end of the pipe profile every revolution. Forces from the ejector rollers and screw jacks are transferred to the winder frame through the adjusting/support frame. The position of the units are adjusted according to the mandrel size by moving the adjusting/support frame in or out from the centre of the mandrel.

[0030] FIGURE 1 illustrates a winder for producing a spirally wound pipe and an ejector in accordance with at least some embodiments of the present invention. The winder has a frame 1 on which is supported a winder star 2. The winder star 2 has several spokes 3, on which a mounted radial support rollers 4. The position of the radial support rollers 4 on the spokes can be adjusted radially in relation to the centre of the winding star 2. The radial position of the radial support rollers 4 is set according to the diameter of the pipe that is manufactured. The mandrel 5 rotates with the main shaft in the centre of the winder star 2. The mandrel is set to rotate by the winder. The mandrel sets the inner diameter of the pipe. During the manufacturing process, the polyolefm pipe that is formed of profile that is wound around the mandrel 5, shrinks, and causes a tight compression between the pipe and mandrel. The shrinking force is directed over a large surface area, whereby the total force is high, keeping the pipe on the mandrel. On the other hand, the end edge of the pipe that is manufactured may still be soft because of heat needed for fusing the successive rounds of profile together to form the pipe. The removal of the remaining piece of pipe requires some force to overcome the friction between the mandrel and the pipe. Simultaneously deformation of the end of the pipe has to be avoided.

[0031] Removal or ejection of the pipe section that is remaining on the mandrel 5 at the end of the production run can be accomplished by various embodiments of the invention. The ejector unit 6 comprises an adjusting/support frame formed of a ejector fastening plate 7 that is mounted between two adjacent spokes 3 of the winding star 2. The ejector fastening plate 7 has two plate parts and a gap therebetween. The edges of the gap are equipped with adjustment rails 8. The main body of the ejector unit, a ejector radial adjustment trolley 9 is mounted transferrable on the adjustment rails 8. The ejector radial adjustment trolley 9 can be moved on the adjustment rails 8 so that its radial position in relation to the centre of the winding star 2 can be set to correspond with the diameter of the mandrel 5 used and the pipe size that is manufactured. The adjustment of the position of the ejector radial adjustment trolley 9 can be made by a hand wheel 10 and a screw, but more feasible solution might be an electric, pneumatic or hydraulic actuator that can be controlled remotely or directly by operating system of the winder.

[0032] The actual pushing elements of the ejector comprise a screw jack assembly

11 that is mounted on the ejector radial adjustment trolley 9 and extends parallel to the longitudinal axis of the mandrel 5 (and the winder star 2) between the spokes 3 of the winder star 2. The screw jack assembly is operated by a motor/gear box unit 15. The end of the screw jack assembly 11 comprises an ejector roller 12 that is set in a crosswise position on relation to the centre axis of the mandrel 5. The ejector roller 12 is mounted to rotate freely around it axis. The ejector roller telescope 13 extends the ejector roller adjusting range. The screw jack assembly can be replaced by a hydraulic actuator and the ejector roller may be replaced by an ejector shoe having a glide surface, a set of parallel rollers or a belt supported by rollers, for example.

[0033] The operation principle of the above described apparatus is described in the following together with some alternatives for various parts of the apparatus. [0034] First, the position of the ejector unit 6 is adjusted according to the mandrel 5 and the pipe size that is manufactured. This is accomplished by moving the screw jack assembly 11 with the ejector roller 12 on the adjustment rails 8 by moving the ejector radial adjustment trolley 9. When the production run of the pipe is finished, the end of the profile that is wound on the mandrel 5 is cut. The profile is cut by hand by an operator or a cutter may be provided for automated cutting. The end of the cut profile forms a step at the end of the pipe. After the profile is cut, the ejector roller 12 can be pushed against the end edge of the pipe. The ejector roller 12 is locked or held in this position. As the profile is wound spirally around the mandrel 5, the end of the pipe is not perpendicular in relation to the longitudinal axis of the mandrel, but the angled according to the rise of the spiral. On the other words, the end forms a part of a screw thread. Now, as the ejector roller is held in set location by the screw jack assembly 11 , rotation of the mandrel 5 pushes the end of the pipe towards the ejector roller 12. As the end of the pipe is angled, the ejector roller 12 pushes the pipe in the direction of the longitudinal axis of the mandrel according to the rise of the angle of the end of the pipe. Thus the section of the pipe remaining on the mandrel is gently removed.

[0035] When the ejector roller 12 reaches the location of the end of the profile, contact with the end of the pipe is released. Now the ejector roller 12 has to be pushed towards the end of the pipe by the screw jack assembly 11 in order to continue ejection of the pipe. The end of the profile or the step formed where the profile is cut, can be detected in several ways. The setting of the apparatus can be done an operator manually so that the operator uses the screw jack assembly 11 as needed. One way is to monitor the rotation of the ejector roller 12 by a suitable detector or controller. The ejector roller 12 is rotated by movement of the end of the pipe and when the contact with the pipe is lost, the rotation stops. This indicates the end of the profile and need to move the ejector roller forward. Another way to monitor this is to monitor the force transferred from the ejector roller to the screw jack assembly 11. When there is a drop in the holding force, loss of contact is indicated. This method might be more suitable in embodiments where hydraulic actuators are used instead of a screw jack. Of course, the end of the profile or the step formed can be detected with any mechanical, optical or other conventional indicator or detector, for example ones that are used as limit switch. One effective way is to monitor the angle of rotation of the mandrel and actuate the screw jack assembly on basis of the angular position. The position of the end of the profile can be set on a control system of the manufacturing apparatus. Further, it must be noted that the forward movement of the ejector roller may be sequenced with any desired angular position of the mandrel and pipe on it as long as the angled end of the pipe and the ejector roller have free space therebetween allowing the movement of the roller. The roller is moved towards the end of the mandrel every time after the end of the profile is detected until the mandrel is completely ejected from the mandrel. Thereafter the ejector roller may be returned to a starting position. One feature that increases the effectiveness of the ejector is the possibility to increase the rotational speed of the mandrel during the ejection process. The manufacturing phase requires low rotational speed. During the ejection much higher speed can be used.

[0036] FIGURES 1 and 3 show the ejector roller in an extended position and

FIGURES 5, 6 and 7 in a rest position close to the winding star 2. FIGURES 5, 6 and 7 illustrate different setups of the winder for manufacturing different sizes of pipes. As can be seen from the figures, the ejector unit 6 can be adjusted accordingly. [0037] The exemplifying example in the FIGURES shows one ejector unit only. The number of units may vary, in one embodiment the number of ejector unit is two in order to provide symmetric force for ejection. If more gentle pushing force is desired, more ejector units and ejector rollers may be used, It can be even contemplated that two or more parallel ejector rollers are used with one screw jack assembly or other linear actuator.

[0038] FIGURES 8 - 10 depict a second example apparatus of the invention. This apparatus can be set on a factory floor below the mandrel 5 (not shown in figs 8 - 10) or alternatively on a support frame to any desired position. However, there is usually free space under the mandrel 5 and floor provides solid ground for support. The apparatus comprises two rails 17 running parallel to each other and connected at their ends by end brackets 18. A carriage 19 is set to run on the parallel rails 17. The carriage 19 is connected to a transfer motor 20 by a screw bar 21. The transfer motor 20 is a unit comprising an electric motor and a gear box for example. On the carriage 19 are mounted two swinging arms 22. The pivot points of the swinging arms 22 are on the carriage and at the free ends of the swinging arms 22 are ejector rollers 12.

[0039] The operation principle of the apparatus shown in FIGURES 8 - 10 is mainly similar as the embodiments previously described and same operation methods may be used. The position of the ejector rollers 12 is adjusted by turning the swinging arms according to the diameter of the mandrel so that the ejector rollers are positioned at correct radial positions in relation of the mandrel. The ejector rollers 12 are moved in longitudinal direction by operating the transfer motor 20, whereby the screw bar rotates and moves the carriage 19. The ejection of the pipe section occurs same way as described above. [0040] Alternative embodiments of the apparatus of figures 8 - 10 can be contemplated. For example, the apparatus may comprise one rail 17 running parallel to the longitudinal axis of the mandrel 5, a carriage 19 mounted on the rail 17, the carriage being transferrable along the rail 17, a linear actuator 20, 21 for transferring the carriage and an ejector element 12 mounted on the carriage 19 by a transfer actuator 22 for adjusting the position of the ejector element 12 in radial direction of the mandrel 5. Other alternative embodiments may be contemplated by combining features of this apparatus to the one described previously.

[0041] It is to be understood that the embodiments of the invention disclosed are not limited to the particular structures, process steps, or materials disclosed herein, but are extended to equivalents thereof as would be recognized by those ordinarily skilled in the relevant arts. It should also be understood that terminology employed herein is used for the purpose of describing particular embodiments only and is not intended to be limiting.

[0042] Reference throughout this specification to "one embodiment" or "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, appearances of the phrases "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily all referring to the same embodiment.

[0043] As used herein, a plurality of items, structural elements, compositional elements, and/or materials may be presented in a common list for convenience. However, these lists should be construed as though each member of the list is individually identified as a separate and unique member. Thus, no individual member of such list should be construed as a de facto equivalent of any other member of the same list solely based on their presentation in a common group without indications to the contrary. In addition, various embodiments and example of the present invention may be referred to herein along with alternatives for the various components thereof. It is understood that such embodiments, examples, and alternatives are not to be construed as de facto equivalents of one another, but are to be considered as separate and autonomous representations of the present invention. [0044] Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. In the following description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention. One skilled in the relevant art will recognize, however, that the invention can be practiced without one or more of the specific details, or with other methods, components, materials, etc. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention.

[0045] While the forgoing examples are illustrative of the principles of the present invention in one or more particular applications, it will be apparent to those of ordinary skill in the art that numerous modifications in form, usage and details of implementation can be made without the exercise of inventive faculty, and without departing from the principles and concepts of the invention. Accordingly, it is not intended that the invention be limited, except as by the claims set forth below.

[0046] The verbs "to comprise" and "to include" are used in this document as open limitations that neither exclude nor require the existence of also un-recited features. The features recited in depending claims are mutually freely combinable unless otherwise explicitly stated. Furthermore, it is to be understood that the use of "a" or "an", i.e. a singular form, throughout this document does not exclude a plurality.

INDUSTRIAL APPLICABILITY

[0047] The invention has industrial applicability in manufacture of spirally wound polyolefm pipes and vessels.

REFERENCE SIGNS LIST

1 winder frame

2 winder star 3 spoke

4 radial support roller

5 mandrel

6 ejector unit

7 ejector fastening plate 8 adjustment rails

9 ejector radial adjustment trolley

10 hand wheel

11 screw jack assembly

12 ejector roller ejector roller telescope motor/gear unit rail

end bracket carriage

transfer motor screw bar

swinging arm