GB2398303A

GB2398303A - Layering fabric or like material

Info

Publication number: GB2398303A
Application number: GB0400877A
Authority: GB
Inventors: Konrad Wegener; Markus Boehn
Original assignee: Schuler Held Lasertechnik GmbH and Co KG
Current assignee: Schuler Held Lasertechnik GmbH and Co KG
Priority date: 2003-01-16
Filing date: 2004-01-15
Publication date: 2004-08-18
Anticipated expiration: 2024-01-15
Also published as: FR2851263A1; DE10301387B4; GB2398303B; DE10301387A1; CA2455273A1; FR2851263B1; GB0400877D0

Abstract

In order to generate wrinkle-free, dense stacks of object sections, for example sections of material for laser cutting, means such as rollers (16, 17) that are arranged in a V and are supported on the gripper carriage (8) so as to be able to rotate, are rolled across a previously formed stack (4) with the gripper carriage (8) that draws off a section of material. The rollers (16,17) may have a coating that is as flexible as possible, so that it can even out irregularities (blade marks) on the cuffing table (3). For the remainder, the coating is such that it has a high coefficient of friction with the material. The uppermost layer of the stack is drawn outward by the action of the rollers (16, 17) and is stretched laterally. In addition, the stack (4) is compacted. The rollers may comprise grooves or discs. Belts may be used instead of the rollers.

Description

Apparatus and Method for Compacting a Fabric Stack The present invention

relates to a layering apparatus for cutting devices, in particular for laser cutting devices, as well as to a method for generating stacks of extensive objects as well as a suitable method.

When cutting out large objects, for example, when cutting textiles, individual layers of such objects must be laid above one another so as to be as free of wrinkles as possible.

Air that is entrained between the individual layers must be removed, for such entrained air disrupts the laser cutting process.

When they are drawn off a bale, textiles frequently display a natural unevenness that is a result of the manufacturing process. For example, textiles with selvage display a certain unevenness, particularly at the edges, if the selvage is slightly longer than the material located further from the edge. If stacks made up of cutout sections of such textiles that are stacked above loosely one another are compressed, this will cause wrinkles, which is extremely disadvantageous.

Proceeding from this, it is the objective of the present invention to create a layering device and a layering method that is or are able to produce wrinkle free and compact stacks.

This objective has been achieved with a layering device as defined in Claim 1, and with the method described in Claim 6.

The layering device according to the present invention has a pull-off device for laying out an extensive object, such as a piece of textile, on a base surface, for example a cutting table. In addition, a smoothing device is also provided, and this can be moved over a large-area object that has already been laid out, or over a stack of such objects, so as to stretch it in a smoothing direction that diverges from the direction of movement.

Because of this, the object (the section of textile) is stretched in divergent directions, which permits largely wrinkle-free smoothing. In addition, the uppermost layer of the stack is pressed against the underlying stack, so that the stack as a whole is compacted.

Such stacks, which have very few wrinkles and no entrained air, can then be subjected to a laser cutting process, when high cutting speeds can be achieved because of the tight layering of the individual pieces. Thus, the layering device according to the present invention makes an important contribution to increasing the output of laser cutting machines.

The smoothing device can be connected directly to a gripper carriage that is moved constantly back and forth over the stack when new layers are being laid on said stack.

The gripper carriage is part of the pull-off device that draws sections of textile from a bale, after which the sections of textile are separated from the textile web.

The smoothing device also includes, for example, at least two elements, the surfaces of which are frictionally engaged with the object that is to be smoothed so as to introduce opposing forces into the object, i.e., in the layer that is to be positioned on the stack. It is preferred that the elements be so movable that the relative movement between the object and the surface of the element that is frictionally engaged deviate from the direction of movement, which is brought about by the smoothing device moving across the stack in a linear direction. Because of this, it is possible to generate opposing forces that stretch the uppermost layer of the stack in a transverse direction whilst the smoothing device is moved lengthwise over the object and the stack. When this is done, the elements are pressed-preferably in a controlled manner-against the object or the underlying stack so as to press this against its base and compact it. Regulation of the downward pressure also makes it possible to raise the smoothing device away from the stack in a controlled manner in order, for example, to disengage the smoothing device from the stack when said smoothing device is on its return path. Alternatively, a smoothing device that is working backwards can be brought into engagement with the stack in order to render the smoothing action symmetrical and to prevent the stack from creeping in the direction in which the smoothing device passes over the stack.

The elements can be rotatably supported rollers so that together they subtend an obtuse angle. It is preferred that this open out in the direction of movement, the cylinders being freely rotatable and caused to rotate by being frictionally engaged with the object. They roll across the object when, because of their inclined position relative to the direction of movement, they work with some slip. This slip generates friction that stretches the object. In addition, the slip generates a retarding force that stretches the object in the direction of movement.

The rollers can be arranged so as to be inclined relative to a horizontal plane so as to make the vertical pressure on the stack, in particular in the middle ofthe stack, greater than at the edges. The stack can be particularly well smoothed and compacted by this means.

It is preferred that the rollers be flexible, or provided with a flexible covering. In addition, it is preferred that the covering have a surface that establishes a coefficient of friction with the material of the object that is greater than the coefficients of friction between the different layers of the stack. This will result in a more effective smoothing and compacting process.

In the simplest case, the rollers can be cylindrical. However, it is also possible to configure the rollers to be cones, truncated cones, barrel shaped, or grooved in order to increase the down pressure and/or to vary the tensioning force that acts transversely to the direction of movement. By this means, it is possible to arrive at force profiles that are optimized for each application, i.e., for each type of material that is to be smoothed.

A spiral shaped helical groove that is made in the outside surface of the cylindrical, barrel-shaped or conical roller can be provided as the grooving that moves the wrinkles in the textile towards the outside. The pitches of the helical grooves of a roller to the right or left of a centre line that lies in the direction of movement are then opposite to each other. In addition, they are so selected that the part of the helical groove that is contact with the textile runs off to the outside when the roller rotates forward.

As an alternative, in place of the pair of rollers it is possible to provide groups of rollers on the same or on separate shafts, as well as discs or wheels on the same or separate shafts. In addition, if needs be they can be driven externally. In one modified embodiment, the elements are in the form of belts that run away from one another.

These belts can run over curved rollers and be self-powered. In addition, this also makes it possible to generate tensioning forces that are transverse to the direction of movement.

In addition to the rollers it is possible, particularly in a central area, to provide a sliding plate or sliding block that engages with the textile ahead of the rollers and then runs on I O this.

Advantageous details of embodiment of the present invention are set out in the drawings, the description and the secondary claims. The drawing show exemplary embodiments of the present invention, namely: Figure 1: A layering device according to the present invention, for a laser cutting machine, in a diagrammatic side view; Figure 2: A smoothing device for the layering device, in a diagrammatic plan view, shown working with a section of textile; Figure 3: A modified embodiment of the smoothing device in a diagrammatic plan view; Figure 4: A further modified embodiment of the smoothing device, in diagrammatic plan view; Figure 5: A further modified embodiment of the layering device, with a modified smoothing device, in side view; Figure 6: The layering device as in Figure S. in front view, at a different scale; Figure 7: A modified embodiment of the smoothing device, in diagrammatic plan view; Figure 8: A further embodiment of the layering device, in a front view.

Figure 1 shows a layering device 1 that is part of a laser cutting machine for cutting material out to size. This also includes a positioning device (not shown herein) for a laser head 2 that is shown diagrammatically and which is position above a cutting table 3. The cutting table 3 has, for example, a flat upper surface that is formed by a mesh (not shown herein). This mesh accommodates a stack 4 of individual sections of material 5, 6. The sections of material 5 that form the stack form objects from which single cutout pieces are to be removed by means of a laser beam. The present invention thus deals with cutting textile fabrics. However, it can also be used to cut out other extensive bodies, for example paper, knitwares, non-woven fabrics, foils/films and the like.

The sections 5, 6 are first drawn off a bale 7 and cut into individual pieces by a separator (not shown herein). A gripper carriage 8 is used to draw the material from the bale; this l S has one or a plurality of grippers 9 and these are designed to clamp on to one edge of a horizontal web of material from which the section 6 is separated in a controlled manner.

The gripper carriage 8 can be moved under control in a horizontal plane, in a horizontal direction H by means of an actuating device (not shown herein).

Together with the grippers 9 and an actuating or drive device (not shown herein), the gripper carriage forms a pull-off device 1 that serves to lay the section 6 on the cutting table 3 or the stack that is being formed thereon. The cutting table 3 or the stack 4 forms the base on which the new section 6 is laid.

The layering device l also has a smoothing devicel2 that serves to press the section 6 onto the cutting table 3 or onto the stack 4 that is already in position thereon, and position the section 6 so that it is free of wrinkles. The smoothing device 12 is connected, for example, to the gripper carriage 8 and can be adjusted in the vertical direction V either with this or separately therefrom. The adjusting system (not shown herein) serves to raise the smoothing device 12 from the stack 4 or else position it on the stack in a controlled manner. When setting the smoothing device 12 down, the adjusting device can release the smoothing device so that it presses down on the stack 4 under its own weight. Alternatively, additional vertical force can be exerted on the smoothing device 12 by a suitable force-generating device, for example a pneumatic device or a spring device, so as to press the smoothing device 12 against the stack 4. s l

The smoothing device is shown in Figure 3, working with the section 5. The smoothing device 12 includes two elements 14, 15, for stretching the section 5 laterally and smoothing it out, and for pressing it against the cutting table 3. In the embodiment shown, the elements 14, 15 are cylindrical rollers 16, 17, that are frictionally engaged with the section 5 in a strip-like area 18. The rollers 16, 17 are rotatably supported in corresponding carriers 21, 22, 23. They are so held that their axes of rotation D1, D2 subtend an obtuse angle a that opens in the direction of movement B. i.e., the ends 24, of the rollers 16, 17 that are adjacent to each other follow the outermost ends 26, 27.

It is preferred that the peripheries of the rollers 16, 17 be provided with a soft covering.

This covering can be of non-woven material, felt, rubber, foam rubber, or the like. The material selected will depend on the material of the sections 5, 6. The selection is such that the friction between the section 5 and the rollers 16, 17 is greater that the friction between the individual section or layers of the stack 4.

A sliding block 28 is arranged in a central area between the rollers 16, 17; this is part of the smoothing device 12 and slides over the object 5. When this happens, the sliding block 28 can serve to compact the stack 4, in particular in the middle area that is not completely covered by the rollers 16, 17. Because of this, it is possible to arrive at a completely compact stack 4 even if the rollers 16, 17 do not cover the whole width of the stack 4. It is preferred that the sliding block be mounted so as to be adjustable transversely to the direction of movement B. so that it can be adjusted to the centre of the fabric.

The layering device described to this extent functions as follows: It is assumed that initially there is no stack 4 on the cutting table 3. The grippers 9 have gripped one edge of a web of material and draw, by a movement of the gripper carriage in Figure 1 from right to left-in the horizontal direction H. the section 6 onto the cutting table 3. When this is done, the section 6 is cut off from the remaining web of the bale 7 by a cutting device. Once the first section is on the cutting table 3, the gripper carriage 8 and with it the smoothing devicel2-which up to now has not performed any function-has arrived at the end of its travel, in Figure 1, the left-hand end. The smoothing device 12 is now moved back from left to right, the rollers 16, 17 moving at a level at which they do not come into contact with the object that has been laid in position.

Now, the grippers 9 once again grip the edge of a section and draw this onto the cutting table 3. When this takes place, the smoothing device 12 is engaged in the section that is already lying in place. The rollers 16, 17 thus run over the section in place, and in so doing they press it downwards against the cutting table 3. As a consequence of the forward movement, the area 18, in which the rollers 16, 17 are engaged in the material of the sections, moves from right to left (Figure 2) above the section. In so doing, they roll across this and press it downwards. When this happens, because of their arrow-shaped or slanted position (a 180) they are of necessity forced into a direction that diverges from the natural direction of roll. This causes slip between the section 5 and the surface of the rollers 16, 17. The resulting force F1, F2 is indicated in Figure 2 by a dashed arrow. It is oriented approximately in the longitudinal direction of the particular roller 16, 17, that is here shown as the direction of coverage S. This means that diverging forces F1, F2 are introduced in to the section 6 as tensioning forces. In addition, this is stretched in the direction of movement B. for the rollers 16, 17 are retarded because of the slippage that occurs. Finally, the rollers 16, 17 are additionally loaded vertically downwards, so that the section 5 is pressed firmly on the underlying section.

The procedure described above is repeated continuously so that a stack 4 is gradually built up, the layers of said stack lying firmly on top of one another, without any wrinkles. Wrinkles are avoided, in particular, by the application of divergent forces.

These forces are directed away from each other into the two areas of the section 5 that lie on the right-hand and left-hand side of the direction of movement B (in Figure 2, obliquely upwards or obliquely downwards) and combine with the tensile force in the direction B to form tensioning forces F3, F4. In Figure 4, these tensioning forces F3, F4 are indicated by arrows.

Figure 3 shows a modified embodiment of a smoothing device 12. This differs from the above-described smoothing device 12 in the configuration ofthe rollers 16, 17. These are grooved. In each of the two rollers this grooving is in the form of a helical groove 29, 31 that is machined into the surface of the roller. The two helical grooves are of opposite pitches, and the pitches are so dimensioned that they both develop a conveyor effect that acts outwards. For example, the groove 31 corresponds to a right-hand thread, whereas the groove 29 corresponds to a left-hand thread. If the smoothing device 12 is now viewed as if it is approaching the observer whilst in engagement with the web of material, the roller 17 is on the left-hand side, whereas the roller 16 is on the right hand side. Rollers with spiral grooves can also be arranged in a manner different from that shown in Figure 3. As an example, the angle a can be almost 180 or exactly 180 or even, if necessary, more than 180 . The rollers 17, 18 can be connected so as to rotate 1 S in unison. If a = 180 , then the rollers 16, 17 can be formed as a roller with right-hand and left-hand counterrotating spiral grooves. In addition, the rollers 16, 17 can be connected to a rotary-drive device. This is particularly useful if a > 180 , i.e., if the rollers 16, 17 form an arrow that has its tip pointing forward in the direction of movement.

Other profiling can be used in place of the grooves 29, 31. For example, the rollers 16 and 17 can be replaced by groups of discs 32, 33 that are mounted on a common shaft.

In extreme cases, it will be sufficient to have just one disc on each of the two shafts. In this case, however, the sliding shoe 28 is made wide enough that it bridges the space between the discs, which run relatively far towards the outside.

As is shown in Figure 5 and Figure 6, it is preferred that the elements 14, 15 be arranged so as to be inclined relative to the horizontal. Their innermost ends 24, 25 are then lower than the outermost ends 26, 27. The rollers 16, 17 subtend an obtuse angle that opens out at the top. This means that the pressure exerted on the stack 4 is greater at the middle than at the sides. The middle carrier 22 be yield somewhat in the vertical direction in order to permit the rollers 16, 17 to press downwards across the whole of their surfaces. An adjusting and loading device can then serve to press the whole of the smoothing device 12 down onto the stack 4, and raise it from the stack. The adjusting and loading device 31 can be part of the gripper carriage 8.

Instead of the inclined position of the elements 14, 15 or of the rollers 16, 17, as shown in Figure 6, the cutting table 3 can have a top surface that is curved transversely to the direction of movement B. Because of this, the downward pressure of the elements 14, on the stack 4 is greater at the middle than it is in the edge areas.

An important feature common to all the embodiments of the smoothing device 12 described heretofore is the generation of a transverse pull in the upper layer of the stack 4 in an area 18 that moves over the stack in the direction of movement B. Such a transverse pull can also be generated by a driven element 14, 15. For example, it is possible to provide all of the elements 14, 15 described heretofore with a rotary drive unit that will drive or brake the elements 14, 15 in a controlled manner. In addition, it is also possible to use belts 35, 36 or discs 32, 33 as well as the rollers 16, 17 that are dimensionally stable, relatively speaking; such belts run in opposite directions over barrel-shaped rollers. On their lower sides, which come into contact with the section 5 or 6 they run away from one another, as is indicated by the dashed arrows in Figure 7.

As is shown, if they are drive externally, the belts 35, 36 can be arranged so as to be oriented in straight alignment with each other, transversely to the direction of movement B. If they are mounted so as to run freely, without any drive system, they can be mounted so as to form an arrowhead.

In order to generate wrinkle-free, dense stacks of object sections, for example, sections of cloth for laser cutting, V-shaped rollers 16, 17 that are installed on the gripper carriage 8 so as to be able to rotate are rolled over an existing stack 4 with the gripper carriage 8, which draws off a section oftextile. The rollers 16, 17 have a coating that is as resilient as possible so that it can smooth out any unevenness (blade marks) on the cutting table 3. Otherwise, the coating is such that is has a high coefficient of friction with the textile. The uppermost layer of textile in the stack is drawn outward and stretched tight by the action of the rollers 16, 17. In addition, the stack is compressed.

Claims

Patent Claims 1. Layering apparatus (I), in particular for cutting

machines, in particular laser cutting machines, with a pull-off device (l l) for laying out an extensive object (6) on a base (3, 4) and with a smoothing device (12) that is moved by an actuating device in a direction of movement (B) over at least one object (5) that is already laid out flat so as to stretch the object (5) in a direction of stretch S that deviates from the direction of movement (B).
2. Layering apparatus as defined in Claim 1, characterized in that the pull-off device (11) is a gripper carriage (8) with grippers (9) that is moved across at least one object (5) that is already laid out in order to lay out the object (6).
3. Layering apparatus as defined in Claim 1, characterized in that the smoothing device (12) is connected to the purl-off device (11).
4. Layering apparatus as defined in Claim 1, characterized in that the smoothing device (12) has at least two elements (14, 15), the surfaces of which are frictionally engaged with the object (5) that is to be smoothed out, in order to introduce opposing forces (F1, F2) into the object (5).
5. Layering apparatus as defined in Claim 4, characterized in that the surfaces of the elements (14, 15) complete movements that contain opposing components.
6. Layering apparatus as defined in Claim 4, characterized in that the elements ( 14, 15) are connected to a drive device that powers the elements (14, 15) in the direction of movement (B), independently of relative movement of the elements (14, 15).
7. Layering apparatus as defined in Claim 4, characterized in that the elements ( 14, 15) are pretensioned against the object (5) in a normal direction (V) in order to press this against its base (4).
8. Layering apparatus as defined in Claim 4, characterized in that the elements (14, 15) are rotatably supported rollers (16, 17), the axes of rotation (D1, D2) of which subtend an obtuse angle (a).
9. Layering apparatus as defined in Claim 8, characterized in that the obtuse angle (a) subtended by the rollers (16, 17) opens out in the direction (B) relative to the direction of movement (B) of the rollers (16,17).
10. Layering apparatus as defined in Claim 8, characterized in that the rollers (16, 17) are arranged so as to be inclined relative to a horizontal, so that their ends that are adjacent to one another (24, 25) are lower than the ends (26, 27) that are remote from one another.
11. Layering apparatus as defined in Claim 8, characterized in that the rollers (16, 17) are supported so as to rotate freely.
12. Layering apparatus as defined in Claim 4, characterized in that the elements (14, 15) are supported so as to be vertically adjustable and pretensioned downward with a loading device.
13. Layering apparatus as defined in Claim 4, characterized in that the elements (14, 15) are so adjusted or configured that the pressure that is exerted on the object (5) is greater at the ends (24, 25) of the elements (14, 15) that are adjacent to each other than that at the ends (26, 27) that are remote from each other.
14. Layering apparatus as defined in Claim 1, characterized in that the base (3) is configured so as to be curved.
15. Layering apparatus as defined in Claim I, characterized in that the curvature of the base (3) is formed be a curve about a line that is parallel to the direction of movement (B).
16. Layering apparatus as defined in Claim 8, characterized in that the rollers (16, 17) are configured so as to be cylindrical.
17. Layering apparatus as defined in Claim 8, characterized in that the rollers (16, 17) are cambered.
18. Layering apparatus as defined in Claim 8, characterized in that the rollers (16, 17) are grooved.
l9. Layering apparatus as defined in Claim 8, characterized in that the rollers (16, 17) have spiral grooves.
20. Layering apparatus as defined in Claim 8, characterized in that the rollers (16, 17) are configured so as to be flexible, or are provided with a flexible covering.
21. Layering apparatus as defined in Claim 4, characterized in that the surface has a coefficient of friction that is greater than the coefficient of friction between the object (5) and the base (3) or between two objects (5, 6).
22. Layering apparatus as defined in Claim 8, characterized in that sliding plates or sliding shoes (28) are provided in addition to the rollers (16, 17).
23. Layering apparatus as defined in Claim 22, characterized in that the sliding shoe (28) is supported so as to be adjustable.
24. Layering apparatus as defined in Claim 4, characterized in that the elements (14, 15) are formed by groups of wheels (32, 33) or discs.
25. Layering apparatus as defined in Claim 4, characterized in that the elements (14, 15) are formed by circulating belts (35, 36).
26. Method for generating wrinkle-free and dense stacks of extensive objects, in which each object is laid on a base (3) or onto a previously generated stack (4) and thereafter smoothed with a smoothing device (12) during generation of combined longitudinal and transverse tension.
27. Method as defined in Claim 26, characterized in that the stack (4) is exposed to a strip-like active area (18) that is moved across the stack (4) in the direction of movement (B) and within which vertical pressure is exerted on the stack (4) and longitudinal tension is exerted on the uppermost layer of the stack (4).