GB2291861A

GB2291861A - Cutting webs in winding machines

Info

Publication number: GB2291861A
Application number: GB9514015A
Authority: GB
Inventors: Armin Hutzenlaub; Dieter Duppengiesser
Original assignee: Kampf GmbH and Co Maschinenfabrik
Current assignee: Kampf GmbH and Co Maschinenfabrik
Priority date: 1994-07-16
Filing date: 1995-07-10
Publication date: 1996-02-07
Anticipated expiration: 2015-07-10
Also published as: DE4425201C2; GB2291861B; GB9514015D0; JPH08175714A; DE4425201A1

Description

TITLE 1 - Method and Device for Separating a Web of Plastics Material

2291861 This invention concerns a method and device for separating a web of plastics material in a reel-cutting and winding machine in which the web of plastics material is guided from a feed reel (primary roll) over a roller located adjacent to a winding reel and separated by means of a hot wire of similar device extending transversely relative to the direction of winding.

Transverse separation of webs of material is used whenever transverse separating blades are difficult to accommodate for reasons of space or, in the case of relatively wide machines, when the rail supports which guide the blades are no longer stable.

An embodiment (Figure 4) of German Patent Specification 36 11 895 uses a hot wire for separating the web of material. This hot wire is connected to an actuator in such a way that it can be moved both in a direction which is axially parallel to a support roller and radially relative to the latter. This actuator is switched on when the hot wire has travelled, by means of pivoted levers, between the web of material and the - 1) support roller and has travelled approximately half the distance to the finished winding reel. This type of separation by means of the hot wire is of complex construction since it requires not only a swivel actuator but also a radial movement. In addition, since the hot wire travels between the web of material and the support roller, the wire can only be heated by the passage of electric current when it is close to the cutting point, as otherwise the web of material would be cut in an uncontrolled manner before this point. Finally, in this method of separation by means of a hot wire, a suction roller or similar device is required in each case so that the free end does not hang downwards within the reelcutting and winding machine. The residual end must be secured and transported to the winding point in which a new winding core is inserted.

One object of this invention is to provide a suitable method, of the type mentioned at the beginning, for separating a web of plastics material in a reelcutting and winding machine by which the web of plastics material is separated rapidly and cleanly in a particularly simple manner, with a residual length which can be predefined in relation to the roller. It is furthermore another object of this invention to provide a device giving optimum separation of the web of plastics material with a predifinable residual length at a particularly low cost and with a minimum space requirement.

In accordance with this invention there is provided a method for separating a web of plastics material in a reel-cutting and winding machine, in which the web of plastics material is guided from a feed reel over a roller disposed adjacent to a winding reel and separated transversely by means of a hot wire or similar device extending transversely relative to the direction of winding, the web of plastics material being separated in a section of the web extending between the feed reel and the roller or between the latter and the winding reel by moving the hot wire of similar device into the plane of the web of material.

The means according to this invention enable the web of plastics material to be separated rapidly and cleanly, for changing the primary roll or in the region between the last roller, that is adjacent to the winding reel and the intake point of the lap on the winding reel. In this case, an appropriate arrangement of the separating device or hot wire or similar device means that the section of web between the intersection point located on the side of the winding reel and the roller always remains constant so that, similarly, winding on to a new winding core always commences under the same conditions. The method according to this invention is therefore advantageous not only for separation but also for feeding the web of material on to a new winding core. The solution according to this invention is space saving and cost effective and, most importantly, does not necessitate any modification to existing machines if these are to be retrofitted with a separating device in the form of a transverse hot wire or similar device. if the hot wire is damaged or destroyed, it can be replaced relatively easily.

A particularly simple and cost-effective solution is achieved if the hot wire of similar device is moved on a circular arc through the section of the web of plastics material which is to be separated. The same result is obviously also achieved if the hot wire or similar device is moved along a linear path through the section of the web of plastics material to be separated.

Irrespective of whether the path of motion is an arc or linear, it is of importance in respect of the invention that the path of motion of the hot wire or similar device is disposed in relation to the position of the section of the web of plastics material to be separated in such a way that the starting end remaining after separation of the web of plastics material is essentially the same length, irrespective of the particular diameter of the winding reel. As stated above, this also produces largely identical winding geometries for the purpose of winding on to a new winding core.

The method for separating a web of plastics material according to this invention means that the hot wire or similar device can be moved very easily inwards and outwards as a radius line, so that the cutting radius becomes variable, in order that the starting length of the web of material remaining up to the roller can be changed or so that the residual length can be kept constant in relation to the finished reel, even when the winding reel is of a different diameter.

The path of motion of the hot wire or similar device can be the same on both sides of the web of plastics material. Preferably, the guide motion is effected on both sides of the web of plastics material by means of a phase shift. This enables the linear cutting force of the hot wire or similar device to be converted into that of a point passing over the width of the web of material, thereby resulting in lesser cutting forces.

A device for separating a web of plastics material in a reel-cutting and winding machine with a roller extending transversely relative to the direction of winding and adjacent to the winding point and with a separating device with a hot wire or similar device extending essentially parallel to the roller is characterised, according to another aspect of this invention, in that the separating device is disposed so that the web of plastics material is separated by means of the hot wire or similar device in a section of the web extending between a feed reel and the roller or between the latter and the winding reel.

It should be noted at this point that the term hot wire obviously also includes braids, cables, narrow bands and similar devices.

In the simplest embodiment, the hot wire extends between retaining arms which are mounted, so as to be capable of swivelling, in a frame of the reel-cutting and winding machine.

It has been shown that particularly favourable and optimal results are achieved if the swivelling axis, and preferably also a swivel actuator of the retaining arms which move past on either side of the roller, are located in a plane lying above the roller. Particularly suitable for adjustment of the hot wire mounting points is a cylinder-piston unit, without a piston rod, located on each retaining arm. The cylinders of these units carry a force transfer element connected through a sealable longitudinal slot to a piston which is capable of being moved forwards and backwards within the cylinder by a pressure medium, the fixing points for the hot wire or similar device being located on the force transfer elements.

Since heating of the hot wire or similar device causes unavoidable elongation of the hot wire which can amount to several centimetres in the case of a wire of several metres long, a pneumatic cylinder-piston unit is connected to at least one end of the hot wire. Unlike a spring, such a cylinder-piston unit delivers the same force at each point and is therefore an excellent means of compensating the longitudinal expansion of the hot wire or similar device.

Preferred embodiments by way of examples of this invention are described in greater detail and illustrated with reference to the drawings, as follows:

Figure 1 shows a schematic representation of a partial view of a reelcutting and winding machine with a separating device according to this invention, Figure 2 shows a schematic representation of the separating device, in a modified embodiment, and Figure 3 shows a further detail of the separating device.

Referring to the drawings a reel-cutting and winding machine indicated only schematically in Figure 1 includes deflection rollers 1,2, over which passes a web of plastics material 3 to be wound, fed from a feed reel (primary roll) which is not illustrated. Located between the deflection roller 2 and the actual winding point 4 there is a roller 6, on a holder 5, over which the web of plastics material 3 is passed from above. Depending on the type of reel-cutting and winding machine, this roller 6 can be constructed as a guide roller, deflection roller, contact roller, bearing roller or similar device. In the area of the winding lap point 4 there is a winding holder with a pair of winding arms 7, only one of which is illustrated. The winding arms 7 can be moved along the curved arcuate path 11 by a cylinder-piston unit 9 via a transfer element 8. In the drawing the winding arms 7 are shown in an intermediate position. Starting from this position, the winding arms 7 can be moved towards the left into the actual winding position 4 and towards the right into a depositing position in which a finished winding reel 14 can be deposited on a support table 12.

As indicated schematically in Figure 1, winding reels 14 of different diameters can be wound as required.

When these reels are complete, they must be separated from the web of plastics material 3. For this purpose there is a separating device 15 which has two retaining arms 16 mounted so as to be capable of a swivelling motion slightly above the roller 6, and a hot wire 18 which is capable of moving along a swivel circle 17. The retaining arms 16 can be moved by a swivel actuator indicated in schematic form, for example a rotary cylinder 19. As also shown by Figure 1, the reference 21 denotes cutting points produced by the points of intersection of the swivel circle 17 and the section 22 of the web of plastics material 3 extending between the windi ng reel 14 and the roller 6. Irrespective of the diameter of the finished winding reel 14, the special nature of the separating device using the hot wire or similar device is such that the cutting points 21 are always located so that residual length of the web of plastics material remaining on the side of the roller 6 remains the same.

This is particularly important in respect of winding the start of a web of material on to a new winding core 13, which is brought into the area of the winding point 4 by the winding arms 7 following the depositing of a finished winding reel.

In the second embodiment of the separating device 15 - shown in Figure 2, each retaining arm 16 is equipped with a cylinder- piston unit 23, without a piston rod, which has connections 24' for a pressure medium. Located inside the cylinder 24 of the cylinder-piston unit 23 there is a piston 25 which can be moved forwards and backwards within the cylinder 24 following application of the pressure medium and can be moved over the distance a. The piston 25 is connected, through a longitudinal slot 26 in the cylinder 24, to a force transfer element 27 to which is fixed the hot wire 18 or similar device. The piston is pressurised to cause the hot wire 18 or similar device to travel upwards and downwards like a radius line on the retaining arm 16 so that the cutting radius becomes variable, in order that the residual length of the web of material remaining up to the roller 6 can be changed or so that the residual length can be kept constant in relation to the finished winding reel with different finished reel diameters. In the embodiment illustrated, the swivelling motion of the retaining arm 16 is effected by a cylinder-piston unit 28.

In Figure 3, one end of the hot wire 18 or similar device is coupled to the retaining arm 16, while its other end is fixed to a cylinder-piston unit 31 which is fixed to the retaining arm 16. This cylinder-piston unit 31 serves to compensate the longitudinal expansion which occurs upon heating of the hot wire or similar device. It has been ascertained, for example, that thermal expansion of about 66 mm occurs on a wire of 8 m in length.

It is of importance, with respect to the present invention, that separation is effected by means of the hot wire or similar device by a simple swivelling or straight-line motion such that the hot wire or similar device is moved into the web of material, in a region located between the winding reel and the last roller 6 being that nearest the winding reel. It is of no importance, with respect to the invention, whether, for the purpose of separating the web of material, the winding reel is moved into an intermediate position or whether the roller is moved into a position away from the winding reel. Narrow strips, braids, cables and similar devices can also be used instead of a hot wire. Finally, the invention is also applicable in unwinding, for example, if it is necessary for the web of plastics material to be separated in order to change the primary roll.

Claims

1. Method for separating a web of plastics material in a reel-cutting and winding machine, in which the web of plastics material is guided from a feed reel over a roller disposed adjacent to a winding reel and separated transversely by means of a hot wire or similar device extending transversely relative to the direction of winding, the web of plastics material being separated in a section of the web extending between the feed reel and the roller or between the latter and the winding reel by moving the hot wire or-similar device into the plane of the web of material.

2. Method according to Claim 1, wherein the hot wire or similar device is moved on an arc of a circle through the section of the web of plastics material to be separated.

3. Method according to Claim 1, characterised in that the hot wire or similar device is moved along a linear path through the section of the web of plastics material to be separated.

4. Method according to any one of Claims 1 to 3, wherein the path of the motion of the hot wire or similar 13 - device is located in relation to the position of the section of the web of plastics material to be separated in such a way that the starting end remaining on the side of the roller after separation of the web of plastics material is substantially the same length irrespective of the particular diameter of the winding reel.

5. Method according to any one of Claims 1 to 4, wherein the path of motion of the hot wire or similar device can be varied in relation to the position of the section of web of plastics material to be separated so that the web of plastics material can be separated as required at intersection points located at different distances from the roller.

6. Method according to any one of Claims 1 to 5, wherein the guided motion of the hot wire or similar device is effected simultaneously and constantly on both sides of the web of plastics material.

7. Method according to any one of Claims 1 to 5, wherein the guided motion of the hot wire or similar ' device is effected on both sides of the web of plastics material by means of a phase shift.

8. Device for separating a web of plastics material in a reel-cutting and winding machine, with a roller extending transversely relative to the direction of winding and located adjacent to the winding point, and with a separating device with a hot wire or similar device, extending substantially parallel to the roller, the separating device being disposed so that the web of plastics material is separated by means of the hot wire or similar device in a section of web extending between a feed reel and the roller or between the latter and the winding reel.

9. Device according to Claim 8, wherein the hot wire or similar device extends between retaining arms which are mounted, so as to be capable of a swivelling motion, on a frame of the reel-cutting and winding machine.

10. Device according to either one of Claims 8 or 9, wherein the swivelling axis, and preferably also a swivel actuator of the two retaining arms moving past the roller on both sides are located in a plane lying above the roller.

11. Device according to any one of Claims 8 to 10, wherein each mounting point of the hot wire or similar device is capable of adjustment on the retaining arms for the purpose of common or separate adjustment of the swivelling.radius.

12. Device according to Claim 11, wherein each retaining arm is equipped with a cylinder-piston unit, without a piston rod, in which the cylinder carries a force transfer element, each accommodating the fixing point for the hot wire or similar device, which is connected to a piston capable of being moved forwards and backwards within the cylinder by a pressure medium, through a sealable longitudinal slot.

13. Device according to any one of Claims 8 to 12, wherein a pressurised cylinder-piston unit is connected to at least one end of the hot wire or similar device.

14. Method for separating a web of material substantially as herein described and exemplified.

15. A device for use in a web winding machine for separating the web of material, substantially as herein described and exemplified with reference to the drawings.