GB2198988A - Welding shoe trimmings - Google Patents

Abstract

Apparatus for use in the high-frequency welding attachment of trimmings to shoes of which the uppers are made of thermoplastics material comprises a shoe-shaped former (2) incorporating an electrode (1, 4), and the method of welding includes inserting the former within the shoe, and welding using also an external electrode. <IMAGE>

Description

High Frequency Welding of Shoe Trimmines The invention relates to apparatus for use in the attachment of trimmings to shoes of thermoplastics material by means of high frequency welding.

Thermoplastics maerials are frequently used in the manufacture of shoe uppers, the term "shoe" being used throughout. the specific 2 ti on, for convenience, to include boots, slippers and other outer footwear.

Such materials, as well as being resistant to moisture and capable of a highly polished and colourful appearance, also possess the advantage of relative cheapness. Hcwever, the very cheapness of the material renders more significant. the costs of the manufacturing steps, and it is a function of the present application to provide a means whereby one such.

manufacturing step, namely the attachment of trimmings, or accessories, to a shoe upper made of thermoplastics material at relatively high production rates and therefore at minimum cost.

It is known to spot weld thermoplastics material by use of a high frequency current passed through the material, but. the technique is not readily applicable to the attachment of trimmings to made up shoes.

According to one aspect of the invention there is provided, for use in the attachment of tr i tr.tn i rigs to shoes made of or comprising thermoplastic material.

a body oompri Si rig a high frequency welding electrode insertable into a made up shoe and externally shaped to conform to the internal shape of a shoe portion. The electrode may comprise a block of metal such as aluminium, at least partly embedded within the body which otherwise comprises a mouldable material such as a plastics material. The electrode block may be extended to constitute means for mounting the electrode ina high frequency welding machine.

Embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, of which the single figure shows an electrode former for use in the manufacture of shoes, in isometric view.

As shown in the figure a T-sectioned block 1 of aluminium is embedded in a body 2 of plastics material formed to the shape of the interior of a shoe toe.

The head 3 of the aluminium block is only embedded by its lower portions in the body 2 and the upper portion projects upwardly from that body portion. The head acts as an electrode and has an upper surface 14 inclined forwardly and downwardly at substantially the slope of the portion of the shoe above which it is intended in use to project.

Inasmuch as the head 3 and the stem 5 of the Tsectioned block have vertical sides and the block may therefore readily be dislodged from within the body 2, the block is provided with outwardly extending pegs 6 in order to anchor it within the body 2.

The stem 5 of the block 1 projects rearwardly of the body 2 and in use it is mounted in a conventional high frequency welding machine, with the head 3 of the block 1 located beneath the upper electrode of said machine.

It is desireable that the body 2 shall fit snugly and accurately within a shoe in order that the correct walking position shall be rapidly located, and for this reason the body 2 preferably is made specifically for a right or for a left shoe and again for a shoe of specific size. The body 2 presents a platform 7 on which the style, size and "hand" may be indicated.

A shoe of which the upper comprises a thermoplastics material is positioned on the former so that the moulding 2 fits inside the toe of the shoe with the inclined surface 4 of the electrode block 1 precisely positioned under the front of the shoe where, commonly, a decorative trimming is required to be affixed. If the trimming is itself made of a thermoplastics material of similar nature to the material of the shoe upper, the shoe and the trimming may be adhered together directly by placing the trimming in the required position, above the surface 4, lowering the upper electrode into contact with the trimming and by passing a high frequency current between the upper electrode and the use of block 1 which acts as a lower electrode.If the trimming is itself not of a suitable thermoplastics material, it may nevertheless be similarly attached to such a shoe by securing the trimming to an attachment member made of such material, laying the attachment member against the shoe over the inclined surface 4, bringing the upper electrode downwards to contact the attachment member and by passing a high frequency current between the electrodes softening the thermoplastics materials of the shoe upper and the attachment member so that they fuse together to form a secure weld. In some circumstances an acceptable weld may be created even if when the high frequency current passes between the electrodes the trimming is interposed between the upper electrode and the attachment member.

The invention is not, of course, limited to the attachment of trimmings to the front of shoes, and it is within the scope of the invention that the body 2 shall be shaped to fit snugly within the heel of a shoe with the head 3 of a T-sectioned aluminium block embedded therein at a position where a trimming is to be attached.

Just as in the embodiment shown in the figure, the upper surface of the head 3 is inclined, so in other embodiments it may, if necessary, be curved and its corners rounded, always provided that the upper electrode can be brought into a close and approximately parallel relationship with the said surface.

The aluminium block shown in the figure may be cut from a single piece of aluminium, but savings may be made in manufacture by forming the head 3 and the stem 5 separately and securing them together by known means.

The width of the head 3 provides that the trimming may be attached to the shoe at laterally spaced positions by use of an upper electrode having laterally spaced downward extensions, but if the trimming can be secured by a single welding spot, the width of the head 3 can be narrowed. In an extreme case a forward extension of the stem 1 will serve instead of a head as illustrated.

Whilst aluminium is the most suitable material for the lower electrode and support bar, other metals such as brass may be used instead. Moreover, whilst the choice of materials for the lower electrode is limited by the requirements of high frequency welding, known in the art, the stem 5 may possibly be made of an alternative material provided that it offers strength to support the former and electrical conductivity to pass the welding current. The body 2 may be formed of any suitable material such as epoxy resin or fibre glass. It may be self-coloured and right and left formers may be colour-coded.

is Experience has shown that sometimes trimmings are required on parts of the shoe other than over the head of the aluminium block as described above, and in order to provide for the attachment of trimmings at any part of the toe of the shoe, the electrode is increased in size in another embodiment by forming the toe shaped body more or less completely of aluminium.

According to a further aspect of the invention there is provided a method of securing a trimming to a shoe of which the upper is made of thermoplastics material comprising the steps, when the trimming is of plastics of other thermofusible material, of placing the trimming in position on the shoe, inserting a shoe shaped body incorporating a first electrode into the shoe so that the said first electrode underlies the trimming, bringing a second electrode into contact with the trimming, and passing a high-frequency current between the electrodes whereby the trimming becomes welded to the shoe.

When the trimming is made of a non-fusible material, the method of attachment includes the step of securing a non-fusible trimming to a fusible body and subsequently attaching the body to the shoe by welding.

Claims (8)

1. Apparatus for use in the attachment of trimmings to shoes of which the uppers are made of thermoplastics material, said apparatus including a body comprising a high-frequency welding electrode insertable into a made-up shoe and externally shaped to conform to the internal shape of a shoe portion.

2. Apparatus according to Claim 1 wherein the body conforms to the internal shape of a shoe front portion.

3. Apparatus according to Claim 1 or Claim 2 wherein the body comprises a metallic electrode at least partly embedded in a different substance.

4. Apparatus according to Claim 3 wherein the different substance comprises a mouldable material such as plastics material.

5. Apparatus according to any preceding Claim wherein the electrode is extended to constitute means for mounting in a highfrequency welding machine.

6 . A method of securing a trimming to a shoe of which the upper is made of thermoplastics material comprising the steps, when the trimming is of plastics of other thermofusible material, of placing the trimming in position on the shoe, inserting a shoeshaped body incorporating a first electrode into the shoe so that the said first electrode underlies the trimming, bringing a second electrode into contact with the trimming, and passing a high-frequency current between the electrodes whereby the trimming becomes welded to the shoe.

7. A method according to Claim 6, when the trimming is made of a non-fusible material, further including the step of securing a non-fusible trimming to a fusible body prior to attaching the body to the shoe by welding.

8. Apparatus for use in the attachment of trimmings to shoes of which the uppers are made of thermoplastics material, substantially as described with reference to the drawings.

9 . A method of securing a trimming to a shoe of which the upper is made of thermoplastics material substantially as described.