GB1600133A - Dielectric heat welding supported polymeric leathercloth - Google Patents

Description

(54) DIELECTRIC HEAT WELDING SUPPORTED POLYMERIC LEATHER CLOTH (71) We, AMALGAMATED LIGHTING (WAITE) LIMITED, a British Company of Menin Works, Bond Road, Mitcham, Surrey, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to dielectric heat welding supported polymeric leathercloth.

'Supported polymeric leathercloth' means herein a textile material comprising natural and/or man made fibres coated on one side with, and thereby supporting, polymeric material to resemble the appearance of leather.

Supported polymeric leathercloth, typically supported p.v.c. leathercloth in which a textile supporting, or backing, material supports a layer of foamed p.v.c provided with a solid p.v.c. top skin remote from the supporting material and resembling the appearance of leather, has been used for some time for the straps and side panels of so-called 'soft' luggage, the straps being stitched onto the side panels in overlying relationship therewith with the backing of the strap adjacent the polymeric material of the panel.

However stitching is time consuming and can result in unacceptable tolerances in the alignment of the straps on the side panels because of the relatively large size of the panels and the associated difficulties in handling them during stitching, and can result in unsightly overstitching.

With a view to overcoming the abovementioned disadvantages we contemplated dielectric heat welding a piece of supported polymeric leathercloth forming a strap onto another piece of such material forming a side panel instead of stitching, but the degree of fusing between the polymeric material of the strap piece and the side panel was inadequate because of the presence therebetween of the backing of the strap piece.

We have now discovered that dielectric heat welding can be successfully used to secure two layers of supported polymeric material together if the layers are arranged with their polymeric material innermost and their backings outermost.

In accordance with the present invention there is provided a method of securing pieces of supported polymeric leathercloth (as hereinbefore defined) together, including joining two overlying pieces with their backings innermost and their polymeric material outermost, thereafter arranging a further piece in at least partially overlapping relationship with said joined pieces with the polymeric material of one of said joined pieces adjacent the polymeric material of the further piece between cooperating electrodes of dielectric heat welding apparatus and operating said apparatus to fuse said polymeric material of said further piece and said one of said joined pieces together.

The method defined in the last preceding paragraph is particularly, although not exclusively, applicable to securing a strap of a travel case to a side panel thereof, the strap being formed by said joined pieces and the panel forming said further piece.

The invention also includes an article in which pieces of supported polymeric leathercloth (as hereinbefore defined) are secured together by a method as defined in the last but one preceding paragraph.

In order that the invention may be well understood, an embodiment thereof which is given by way of example only, will now be described, reference being made to the accompanying drawings, in which: Figure 1 is a perspective view of a travel case; Figure 2 is an enlarged cross-seetion of one of the straps of the case; Figure 3 is a schematic elevational crosssection through heat welding apparatus for securing the straps to a side panel of the case; Figure 4 is a plan view of a jig for positioning the straps and side panel prior to heat welding; and Figure 5 illustrates the area of heat welds between the straps and the panel.

Referring to the drawings, there is shown in Figure 1 a travel case 1 including a side panel 2 of a cotton backed p,v.c. leathercloth material to which are secured by dielectric heat welding three straps 3, 4 and 5.

Each strap is formed of two overlying pieces 6, 7 of similar material which are joined as shown in Figure 2 with their cotton backings 8 innermost, or adjacent, and their p.v.c. layers 9 outermost. The pieces 6, 7 are joined together by double rows of stitching 10 as indicated at 11 in Figure 2 which in the finished case gives the appearance of the strap being sewn onto the side panel (see Figure 1) rather than heat welded thereto.

The straps are heat welded to the side panel by means of high frequency dielectric heat welding apparatus schematically illustrated at 12 in Figure 3 and comprising electrodes 13 and 14. Electrode 13 is an earthed bed, and electrode 14, often referred to as an arc, is moveable towards and away from the bed.

A jig 15 (Figure 4) is located on the bed 13 in a predetermined position and the straps are positioned in respective cut-outs 16. Thereafter, the piece of material forming the side panel 2 is located in the main cut-out 17 with its p.v.c. layer downmost adjacent the straps.

Thus the straps are positioned on the bed 13 under the side panel 2, the panel being in overlapping relationship with strap 3 and in partially overlapping relationship with straps 4 and 5.

The electrodes 14 are moved into engagement with the backing of the side panel to press the panel against the straps and to fuse the p.v.c. layer of the side panel piece and the adjacent p.v.c. layers of the straps.

It is the electrodes or anodes 14 rather than the bed which tends to become warm during operation, and by arranging for the anodes 14 to contact the backing rather than the p.v.c.

material of the straps, which would be the case if the straps were positioned on top of the panel instead of under it, spoiling of the p.v.c. material which typically has a grain effect, or flattening the material, is avoided.

Also the problem of the anodes sticking to the p.v.c. material is avoided.

The anodes 14 have flat working surfaces which enable the fusing to extend over a large area. Further, the working surfaces of the anodes overlap the edges of the straps so as to provide a tolernace in the alignment of the anodes and the straps which avoids the problem of the strap edges turning up if an edge of an electrode acts just inside a strap edge.

In the embodiment the anodes are recessed at 18 and 19 in order to reduce the area of the weld to an area within the capacity of the machine used. The resulting areas of weld 20 and 21 are indicated with cross-hatching in Figure 5.

It is possible for air to be expanded and trapped in the areas 22 and 23 within the weld area between the backings 8 of the pieces of material forming the straps to cause a slight bubble, and in order to obviate this the recess of the electrode may be filled in with a non-conductive material (not illustrated) which engages the panel momentarily before and during welding.

Advantageously, the jig may be formed with the same rules that cut out the panel and strap pieces to ensure accurate location for these pieces.

It will be appreciated that as well as enabling the straps to be secured more accurately on the panel than if stitching were used, the described method enables the time taken in securing them to be drastically reduced. The appearance of the straps being stitched to the panels is achieved since the pieces forming the straps are stitched together, this operation being acceptable since the size of the pieces enables them to be easily handled.

It is to be understood that the described method of securing pieces of supported polymeric material together is applicable to the manufacture of items other than travel cases although it has been described in relation to such manufacture.

WHAT WE CLAIM IS: 1. A method of securing pieces of supported polymeric leathercloth (as hereinbefore defined) together, including joining two overlying pieces with their backings innermost and their polymeric material outermost, thereafter arranging a further piece in at least partially overlapping relationship with said joined pieces with the polymeric material of one of said joined pieces adjacent the polymeric material of the further piece between cooperating electrodes of dielectric heat welding apparatus and operating said apparatus to fuse said polymeric material of said further piece and said one of said joined pieces together.

2. A method as claimed in claim 1, wherein said electrodes comprise a bed of the apparatus and an electrode movable towards and away therefrom, and wherein said joined pieces and said further piece are positioned on said bed with said further piece in said at least partially overlapping relationship with said joined pieces.

3. A method as claimed in claim 2, wherein said joined pieces are positioned under said further piece on said bed such that said movable electrode engages the backing of said further pieces during operation of said apparatus.

4. A method as claimed in claim 2 or 3, wherein said movable electrode overlaps said joined pieces.

5. A method as claimed in any one of claims 1 to 4 when used for securing a strap to a panel of a travel case, said strap being formed by said joined pieces and said panel forming said further piece.

6. A method of securing two pieces of

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. material to which are secured by dielectric heat welding three straps 3, 4 and 5. Each strap is formed of two overlying pieces 6, 7 of similar material which are joined as shown in Figure 2 with their cotton backings 8 innermost, or adjacent, and their p.v.c. layers 9 outermost. The pieces 6, 7 are joined together by double rows of stitching 10 as indicated at 11 in Figure 2 which in the finished case gives the appearance of the strap being sewn onto the side panel (see Figure 1) rather than heat welded thereto. The straps are heat welded to the side panel by means of high frequency dielectric heat welding apparatus schematically illustrated at 12 in Figure 3 and comprising electrodes 13 and 14. Electrode 13 is an earthed bed, and electrode 14, often referred to as an arc, is moveable towards and away from the bed. A jig 15 (Figure 4) is located on the bed 13 in a predetermined position and the straps are positioned in respective cut-outs 16. Thereafter, the piece of material forming the side panel 2 is located in the main cut-out 17 with its p.v.c. layer downmost adjacent the straps. Thus the straps are positioned on the bed 13 under the side panel 2, the panel being in overlapping relationship with strap 3 and in partially overlapping relationship with straps 4 and 5. The electrodes 14 are moved into engagement with the backing of the side panel to press the panel against the straps and to fuse the p.v.c. layer of the side panel piece and the adjacent p.v.c. layers of the straps. It is the electrodes or anodes 14 rather than the bed which tends to become warm during operation, and by arranging for the anodes 14 to contact the backing rather than the p.v.c. material of the straps, which would be the case if the straps were positioned on top of the panel instead of under it, spoiling of the p.v.c. material which typically has a grain effect, or flattening the material, is avoided. Also the problem of the anodes sticking to the p.v.c. material is avoided. The anodes 14 have flat working surfaces which enable the fusing to extend over a large area. Further, the working surfaces of the anodes overlap the edges of the straps so as to provide a tolernace in the alignment of the anodes and the straps which avoids the problem of the strap edges turning up if an edge of an electrode acts just inside a strap edge. In the embodiment the anodes are recessed at 18 and 19 in order to reduce the area of the weld to an area within the capacity of the machine used. The resulting areas of weld 20 and 21 are indicated with cross-hatching in Figure 5. It is possible for air to be expanded and trapped in the areas 22 and 23 within the weld area between the backings 8 of the pieces of material forming the straps to cause a slight bubble, and in order to obviate this the recess of the electrode may be filled in with a non-conductive material (not illustrated) which engages the panel momentarily before and during welding. Advantageously, the jig may be formed with the same rules that cut out the panel and strap pieces to ensure accurate location for these pieces. It will be appreciated that as well as enabling the straps to be secured more accurately on the panel than if stitching were used, the described method enables the time taken in securing them to be drastically reduced. The appearance of the straps being stitched to the panels is achieved since the pieces forming the straps are stitched together, this operation being acceptable since the size of the pieces enables them to be easily handled. It is to be understood that the described method of securing pieces of supported polymeric material together is applicable to the manufacture of items other than travel cases although it has been described in relation to such manufacture. WHAT WE CLAIM IS:

1. A method of securing pieces of supported polymeric leathercloth (as hereinbefore defined) together, including joining two overlying pieces with their backings innermost and their polymeric material outermost, thereafter arranging a further piece in at least partially overlapping relationship with said joined pieces with the polymeric material of one of said joined pieces adjacent the polymeric material of the further piece between cooperating electrodes of dielectric heat welding apparatus and operating said apparatus to fuse said polymeric material of said further piece and said one of said joined pieces together.

2. A method as claimed in claim 1, wherein said electrodes comprise a bed of the apparatus and an electrode movable towards and away therefrom, and wherein said joined pieces and said further piece are positioned on said bed with said further piece in said at least partially overlapping relationship with said joined pieces.

3. A method as claimed in claim 2, wherein said joined pieces are positioned under said further piece on said bed such that said movable electrode engages the backing of said further pieces during operation of said apparatus.

4. A method as claimed in claim 2 or 3, wherein said movable electrode overlaps said joined pieces.

5. A method as claimed in any one of claims 1 to 4 when used for securing a strap to a panel of a travel case, said strap being formed by said joined pieces and said panel forming said further piece.

6. A method of securing two pieces of

supported polymeric leathercloth (as hereinbefore defined) together substantially as herein described with reference to the accompanying drawings.

7. An article in which pieces of supported polymeric leathercloth (as hereinbefore defined) are secured together by a method as claimed in any one of the preceding claims.

8. A travel case having at least one strap secured to a panel thereof by a method as claimed in claim 5.