WINDING DEVICE

Abstract

The invention relates to a winding device for winding a travelling web of material, said winding device comprising at least one blade for slitting the web of material in the web direction into several partial webs of material and comprising a folding device for folding over the edges of the partial webs of material In order to provide a winding device that allows a web of material to be wound with folded over edges in the simplest possible manner and without folds, an oscillating device is provided, with which the at least one blade can be moved transversely to the direction of the web.

Description

The invention relates to a winding device for winding a travelling web of material, said winding device comprising at least one blade for slitting the web of material in the web direction into several partial webs of material and comprising a folding device for folding over the edges of the partial webs of material.

A winding device of this type is known from the U.S. Pat. No. 8,221,298 B2 and is used, in particular, for winding stretch films.

Stretch films are used to secure and package individual items, for example, on pallets. At the same time the items are wrapped with the stretch film, so that the items are connected to each other with the aid of the self-adhesive stretch film.

It has been found that the edges of stretch films are often the starting point for the film to tear during the wrapping operation on the pallet. Even minor damage to the edge of a stretch film roll can make this roll unusable, a feature that is particularly critical when the film is to be applied by hand. Such damages may result, for example, from the finished wound roll of stretch film being improperly handled during transport or being dropped on the ground.

Furthermore, it is also known that the stretch film is more resistant to damage if the edges are folded over or creased before the stretch film is wound on a roll, with the effect that the stretch film is less likely to tear. However, if the edges are folded over, the result is that the edges of the roll of film will be inadmissibly thick and hard during straight edge winding.

When folding over, it is necessary to cyclically offset the edges of the film to one side of the roll. This can be done, for example, by laterally oscillating the reel or by means of angularly moveable guide rollers, after individual reel slitting.

However, reversing or oscillating the web of film prior to winding can, in turn, produce folds, which in turn may impair the function of the film.

Based on the aforesaid, the object of the present invention is to provide a winding device that allows a web of material to be wound with folded edges in the simplest possible manner and without folds.

This object is achieved by means of an oscillating device, with which the at least one blade can be moved transversely to the direction of the web.

Hence, an essential element of the invention is the feature of oscillating the cutter bar, used for slitting the reel, transversely to the direction of the film. The devices for folding over the edges after slitting the reel are fixed either on the same cutter bar and execute accordingly the same oscillatory motion as the blades, or said folding devices are attached to a bar, which is located downstream of the cutter bar and which executes an oscillatory motion that is synchronized with the cutter bar.

As a result, the folded over edges are laterally offset on the resulting stationary reel, and a winding with reduced edge structure is possible. In this case the stroke and frequency of the motion are adjustable and can be adapted, if desired, as a function of the web speed, the film thickness and the increasing diameter of the roll, so that the result is an optimal edge geometry.

For the subsequent folding device for producing the folded side edge, there are a number of variants. One variant consists of the feature that one folding device is provided for each folded over edge. Each of these folding devices can be used either directly side by side or one after the other. It is also conceivable that the devices for folding over the edges dip centrally into the slit in order to start up, so that they have an effect on both edges; and, in the course of dipping, said folding devices are altered in position or shape due to the appropriate kinematics in such a way that they only affect one edge. This can be done either simultaneously or sequentially for adjacent edges.

Another variant of a folding device consists of the feature of producing a strip cut-out of several reels and of removing said strip cutout by suction. Then it would be possible to produce a space between the two edges by means of the strip cutout, a design that allows the respective edges to be folded over separately.

The invention has a number of advantages over the prior art.

The prior art methods for lateral oscillation of the folded edges are often very complex, since each one of the reels has to be oscillated individually after the reel slitting. For this purpose, additional devices are required that are usually expensive, complicated and maintenance intensive.

According to the solution of the invention, there is also no limit with respect to the width of the reel and the number of reels.

According to a preferred embodiment, it is provided that the oscillating device comprises a driven belt, to which the at least one blade is attached. The belt may be, for example, a continuous toothed belt, which is moved by a gearwheel, which is driven by an electric motor.

According to an additional preferred embodiment, it is provided that the oscillating device comprises a cutter bar, which is driven by a linear motor and to which the at least one blade is attached.

In addition, preferably a control unit for actuating the oscillating device is provided. As a result, the control device can be used to specify all possible movements or, more specifically, slitting patterns. In particular, it is also conceivable that the thickness profile of the wound roll is continuously measured; and the oscillating device is actuated, as a function of the measured thickness profile, in such a way that the result is a thickness profile that is as uniform as possible.

The invention may be applied in a particularly advantageous way to the winding operation of stretch films that were produced on a cast film extrusion line or a blown film line.

Additional details and advantages of the invention will be explained below with reference to the accompanying drawings. The drawings show in:

FIG. 1 a first embodiment of the invention; and

FIG. 2 a second embodiment of the invention.

FIG. 1 shows a first embodiment of the invention. The web of material 101 is a stretch film produced on a cast film extrusion line.

After the stretch film 101 has been produced, it is transported in the direction 102 and, as a result, reaches the cutter bar 103. The cutter bar 103 is moved back and forth in the direction 104 by means of an oscillating device and has a total of five cutting blades 105. To the left and the right of the edges there is in each instance a cut back 111 and 112, which can be further processed for other purposes.

Behind the cutter bar 103 there are S-shaped strips 106, 107, 108 and 109, and, in particular, approximately in the shape, as shown in FIG. 1. In this embodiment the S-shaped edge does not have to be uniform. The amplitude and frequency of the movement of the oscillating device can also be irregular. Moreover, it is also conceivable that the individual blades 105 are individually actuated and, therefore, execute a number of different movements.

FIG. 2 shows a second embodiment of the invention. The web of material 201 is, once again, a stretch film produced on a cast film extrusion line.

After the stretch film 201 has been produced, it is transported in the direction 202 and, as a result, reaches the cutter bar 203. The cutter bar 203 is moved back and forth in the direction 204 by means of an oscillating device and has a total of three cutting blades 205. Since the outermost edges are left untrimmed on the left and the right, there is, in contrast to the embodiment according to FIG. 1, no cut back.

Behind the cutter bar 203 there are S-shaped strips 206, 207, 208 and 209, and, in particular, approximately in the shape, as shown in FIG. 2, in this embodiment the S-shaped edge does not have to be uniform. The amplitude and frequency of the movement of the oscillating device can also be irregular. Moreover, it is also conceivable that the individual blades 205 are individually actuated and, therefore, execute a number of different movements.

The outer strips 206 and 209 have in each instance a straight edge and an S-shaped edge and are further processed in this shape for specific purposes.

Claims

1. Winding device for winding a travelling web of material,

comprising at least one blade for slitting the web of material in the web direction into several partial webs of material and

comprising a folding device for folding over the edges of the partial webs of material,

characterized by

an oscillating device, with which the at least one blade can be moved transversely to the direction of the web.

2. Winding device, as claimed in claim 1, characterize in that the oscillating device comprises a driven belt, to which the at least one blade is attached.

3. Winding device, as claimed in claim 1, characterize in that the oscillating device comprises a cutter bar, which is driven by a linear motor and to which the at least one blade is attached.

4. Winding device, as claimed in claim 1, characterize by a control unit for actuating the oscillating device.

5. Winding device, as claimed in claim 1, characterize in that the web of material is a stretch film produced on a cast film extrusion line or a blown film line.