GB2141097A - Pallet for holding a workpiece - Google Patents

Abstract

A pallet for an automatic sewing machine has a work- receiving cavity (20) having re- entrant wall portions, and comprises a plate member (10) made up of three or more layers (12, 14, 16) laminated together. The cavity (20) is made up of separate cavities (22, 24, 26) formed in the various layers prior to their lamination together. The dimensions of the cavity (24) in the intermediate layer(s) (14) are larger than the other cavities (22, 26) so that the outer layers (12, 16) project beyond the cavity formed in the intermediate layer (14). The dimensions of the cavity (24) in the intermediate layer(s) (14) correspond to the dimensions of the workpiece to be held in the pallet. In this way, the workpiece can be "clipped" in the cavity (20). The dimensions of the cavity (26) in the lower outer layer (16) may be smaller than those of the cavity (22) of the upper outer layer (12), so that additional support is given to the edges of the workpiece beneath it while not impeding the insertion of the workpiece into the cavity (20). <IMAGE>

Description

o SPECIFICATION Pallet for holding a workpiece This invention is concerned with a pallet for holding a workpiece as it is moved along a desired path relative to an operating tool, e.g.

in automatic stitching machines.

Conventionally pallets of this type comprise one or more plate members, in which (or each of which) is formed a workpiece-receiving cavity the dimensions of which correspond to those of a workpiece to be received in said cavity, the "base" of each such cavity being provided by a further plate member therebeneath (or by a workpiece component placed in such further member). For holding the workpiece in position in its cavity, or indeed for clamping a number of workpiece components in their several cavities, customarily the pallet also comprises a base plate, to which the other member or members may be hinged, the base plate having cut-out cavities dimensioned merely to allow the passage of an operating tool, e.g. a reciprocating needle, therethrough.In addition, the pallet may comprise either a top plate, also hinged to the other plate members and having similarly dimensioned cavities to the base plate, or clamps may be provided for clamping the workpieces to be stitched in position.

It is the object of the present invention to provide a simpler construction of pallet in which workpieces can be "clipped" in their cavities without the need for special clamps or additional top and base plates.

The invention thus provides a pallet for holding a workpiece as it is moved along a desired path relative to an operating tool, said pallet comprising a plate member in which is formed a workpiecereceiving cavity having opposed re-entrant wall portions, wherein the plate member is made up of at least three layers laminated together, the dimensions of the cavity formed in the or each intermediate layer corresponds to those of a workpiece to be received in said cavity, and the dimensions of the cavity in each outer layer are smaller than those of the cavity of the intermediate layer(s), and thus the outer layers project beyond the intermediate layer(s), at least along the length of said opposed wall portions.

By so forming the wall portions of the workpiecereceiving cavity of the plate member, it will be appreciated, a workpiece can be inserted into the cavity and its edges can be "clipped" between the outer layers of the plate member along the edges of the workpiece in the region of the re-entrant wall portions.

If it is desiredto stitch around the whole of the periphery of the workpiece, furthemore, preferably the dimensions of the cavity of each outer layer are smaller than those of the cavity of the intermediate layer(s), and thus the outer layers project beyond the intermediate layer(s), along the whole of the periphery thereof.

The dimensions of the cavity of each outer layer may be the same, but preferably the dimensions of the cavity of the upper outer layer are smaller than those of the cavity of the lower outer layer, and thus the latter projects beyond the upper outer layer along the wall portions of the cavity. By so arranging the outer layers, the projecting portion of the upper outer layer does not interfere with the loading of a workpiece into the cavity, while the extra projection on the lower outer layer provides additional support for the edges of the workpiece thus loaded.

It will of course be appreciated that, where a peripheral stitching pattern is to be followed, the amount of projection of the outer layers must be restricted accordingly. In practice, conveniently the distance by which the lower outer layer projects beyond the upper outer layer as aforesaid is of the order of 0.5mm, and similarly the distance by which the upper outer layer projects as aforesaid beyond the intermediate layer(s) is of the order of 0.5mm.

In manufacturing a pallet in accordance with the invention, a conventional automatic punching machine can conveniently be used.

Furthermore, the differences in the dimensions of the cavity can be achieved by using punches of different size, while nevertheless using the same digitised information fed to the automatic punching machine. In this way, the accuracy of alignment of the various cavities in relation to one another is rendered significantly more reliable. After the separate layers have been punched, furthermore, pre ferabiy they are laminated together using adhesive.

The various layers of the pallet may be made of any suitable sheet material. In general, aluminium is preferred, depending upon the thickness of the layer. Thus, the upper outer layer is for example in the region of 0.9mm thick and is thus self-supporting and can be readily punched on the automatic punching machine. In the case of the lower outer layer, on the other hand, it may be that a thinner material thickness is required, e.g.

of the order of 0.6mm; for example, where the pallet is for use with an automatic stitching machine, a thin lower outer layer serves to dispense with the need for a rising throat plate. In such a case,it has been found that a stronger material, e.g. sheet steel, is preferred, in order to avoid distortions during the punching operation. The thickness of the intermediate layer or layers is of course determined according to the thickness of the workpiece. Thus, a single intermediate layer may be used or two or more layers may be laminated together to provide the desired thick ness.

The pallet in accordance with the invention may be provided for holding workpieces for a decorative stitching operation to be performed thereon, especially along peripheral portions thereof, and in this regard is especially suitable for use with straps, forming part of shoe uppers. It may, however, also be used readily for "join-and-sew" operations on such straps.

There now follows a detailed description, to be read with reference to the accompanying drawings, of one pallet in accordance with the invention, this pallet having been selected for description merely by way of exemplification of the invention and not by way of limitation thereof.

In the accompanying drawings: Figure 1 is a perspective view showing details of the pallet now to be described; and Figure 2 is a section along the line ll-ll of Figure 1.

The pallet now to be described is a pallet for use with an automatic sewing machine, more especially for holding a workpiece, in the form of an upper strap component, in position for forming a decorative stitch pattern along the periphery thereof and also for performing a "join-and-sew" operation part way along the length of the workpiece. To this end, the pallet comprises a plate member generally designated 10 comprising three layers 12,14,16 laminated together using adhesive. One adhesive which has been found.

especially suitable is identified as a "Hyperbond" adhesive available from Bostik Limited.

The thickness of the intermediate layer 1 4 is set according to the thickness of the workpiece to be stitched; thus, in the case of a comparatively thick workpiece it may be desirable to laminate two intermediate layers together. The upper outer layer 1 2 is preferably of the order of 0.9mm thick, while the lower outer layer 1 6 is somewhat thinner, preferably of the order of 0.6mm. In this way, the need for a rising throat plate in the automatic sewing machine is avoided. The upper outer and intermediate layers 12,14 are made of aluminium, while the lower outer layer is made of sheet steel. For mounting the pallet in an automatic sewing machine, furthermore, a mounting plate 1 8 is riveted or otherwise secured to the plate member 10.

The plate member 10 is provided with a workpiece-receiving cavity generally designated 20, having re-entrant wall portions. The cavity is formed separately in each of the layers 1 2,14,1 6 of the plate member 10 prior to their being laminated together, so that cavities 22,24,26 which are differently dimensioned from one another can be provided in each layer. Thus, the dimensions of the cavity 24 formed in the intermediate layer 14 correspond to those of the workpiece to be received in the cavity. For "clipping" the workpiece along its edges in the cavity, on the other hand, the dimensions of the cavity 22,26 in each of the outer layers 1 2,1 6 are larger, so that the outer layers project beyond the cavity of the intermediate layer.More particularly, the upper outer layer 1 2 projects beyond the cavity of the intermediate layer 1 4 by some 0.5mm, while the lower outer layer 16 projects by a further 0.5mm beyond the upper outer layer. (It will of course be appreciated that the two outer layers 14, 1 6 may project by the same amount beyond the edge of the cavity 24 of the intermediate layer).

Whereas in the pallet described, the workreceiving cavity 20 is provided with re-entrant wall portions along the whole of its periphery, in other pallets in accordance with the invention the re-entrant wall portion may extend along only part of the periphery of the workreceiving cavity, provided that in each case opposed re-entrant wall portions are provided, so that the workpiece can be "clipped" along opposed edges, thereby ensuring that the workpiece is secure in the pallet.

In using the pallet in accordance with the invention, the operator places the workpiece over the cavity 20 and presses it into the cavity so that its edges are clipped between the projecting portions bounding the cavities 22,26,of the outer layers 1 2,1 6. In the case of a workpiece made up of two components requiring a small "join-and-sew" operation to be performed at the same time, the two components are located separately, with the regions to be joined arranged in overlapping relationship; conventionally, the region of each of the components will have been previously skived. The pallet is then located in the automatic sewing machine by means of the mounting plate 1 8 and the operation can then take place automatically in a conventional manner.

The pallet is suitable for use with any material customarily used in the manufacture of shoe uppers, e.g. leather, poromeric and PVC material, and can be used in other applications with materials of similar stiffness.

Claims (9)

1. A pallet for holding a workpiece as it is moved along a desired path relative to an operating tool, said pallet comprising a plate member in which is formed a workpiecereceiving cavity having opposed re-entrant wall portions, wherein the plate member is made up of at least three layers laminated together, the dimensions of the cavity formed in the or each intermediate layer corresponds to those of a workpiece to be received in said cavity, and the dimensions of the cavity in each outer layer are smaller than those of the cavity of the intermediate layer(s), and thus the outer layers project beyond the intermediate layer(s), at least along the length of said support wall portions.

2. A pallet according to either Claim 1 wherein the dimensions of the cavity of each outer layer are smaller than those of the cavity of the intermediate layer(s), and thus the outer layers project beyond the intermediate layer(s), along the whole of the periphery thereof.

3. A pallet according to either one of the preceding Claims wherein the dimensions of the cavity of the upper outer layer are smaller than those of the cavity of the lower outer layer, and thus the latter projects beyond the upper outer layer along the wall portions of the cavity.

4. A pallet according to Claim 3 wherein the distance by which the lower outer layer projects beyond the upper outer layer as aforesaid is of the order of 0.5mm.

5. A pallet according to any one of the preceding Claims wherein the distance by which the upper outer layer projects as aforesaid beyond the intermediate layer(s) is of the order of 0.5mm.

6. A pallet according to any one of the preceding Claims wherein the layers of the plate member are laminated together using adhesive.

7. A pallet according to any one of the preceding Claims wherein the lower outer layer is made of sheet material having a thickness of the order of 0.6mm.

8. A pallet according to Claim 7 wherein the lower outer layer is made of sheet steel.

9. A pallet constructed as hereinbefore described with reference to the accompanying drawings.