US2240867A - Last - Google Patents

Description

Patented May 6, 1941 UNITED. stares PATENT cerros Y LAST .lohn Frederick Smith, Quincy, Mass., assignor to Compo Shoe Machinery Corporation, Boston, Mass., a corporation of Delaware Application August 26, 1938, Serial No. 226,915

2 Claims.

This invention relates to the manufactureV of cemented footwear in which an adhesive is electrically heated, and more particularly to an electrode equipped last useful in such manufacture.

A process of joining' shoe parts withadhesive heated by an energized. field created by high-frequency electrical current is described in United States Patent No. 2,087,480: issued to E. C. Pitman on July 20, 1937, and improved apparatus for carrying out suchprocess is describedin United States PatentNo. 2,109,323 issued to J. F. Smith on. February 22; 1938; The present invention concernsa last onwhich shoes are adapted to be made in accordance with theprocedures described in said patents.

A general object of the invention is to provide a lastof electrically non-conductive material having conductive portions or surfaces congured and disposed to oppose selected areas of a shoe, and having convenient means for supplying electrical'energy to such portions or surfaces.

Y More particularly, objects of the invention are to provide a last having'anelectrode which may Other objectsof the invention will in part be obvious Land: will' in. part' appear hereinafter.

IThe invention, accordingly comprises the features* Vof construction, combination of' elements,

and arrangement of parts, which will be exemplified-intheconstruction hereina'ter set forth and the scope of the invention will be indicated inthe claims;V

For a-rfuller understanding of v the nature and objects-of theinvention reference should be had to4 the following' `detailed description taken in connection with: the accompanying drawing, in

Fig. 14 is a, side elevation of a last embodying features of the invention,v part thereof being broken'away 4better to show the construction;

Fig. 2 is ai side'elevatienA of another form of thefinventionas embodied in a hinged last, parts thereof being broken away;

Fig. 3 isa=bottcrn viewof the last shovvnin Fig: 2;- and CII Fig. 4 is a transverse sectional View across the forepart portion of the last of Fig. 2.

Referring more particularly to the drawing and rst. to Fig. l there is shown a last l0 of solid or unhinged construction which is provided with improved means enabling it to be used to advantage in shoe cementing processes such as those described in the mentioned Pitman andSmith patents. These processes involvethe heating of an adhesive which is placed between electrodes or terminals arranged in the manner of condenser plates in a high frequency oscillating circuit. When thebottom portions of a shoe are tol be adhesively bonded in this manner, as for eir-V ample when the outsole is being cemented to the upper or the upper materials are being cement lasted, one of these electrodes is placed on the bottom of the last and another on the underlying surface of the pressure diaphragm which is provided in the conventional shoe pressing equipment. As the most intense heat is developed in the dielectric space immediately between the opposed electrodes the area to be treated can be controlled by suitable configuration and disposition of the electrode on the last.

Thus, in Fig. 1 the last' l, which is of electrically non-conductive material such as woodv or a suitably molded plastic or the like, has on itsbottorn an electrode Il which, as illustrated, may comprise an electrically conductive metallic plate, of copper or other suitable material. These terms electrically non-conductive and electrically conductive or other terms of similar import as used throughout the present specication and claims are intended to be relative. That is, the shoe last' shouldk desirably be made of materials such as wood or others, having a high dielectric strength', which are suiiiciently resistant to ordinary currents atk ordinary frequencies to be usually regarded as non-conductive, even though their resistant or insulative effect may be largely reduced or even substantially nullied in a iieldhaving the extremely high-frequencies employed in the processes contemplated by the present invention. The electrode is of material having relatively low electrical resistance as compared With the last body, being "conductive in the sense that it is sulciently relatively nonresistant to afford a means of localizing and dening the vicinity of the most intensive high frequency eld action. This electrode may extend over the entire bottom of the last if full bottom cementing is Wanted, or may be limited to selected areas. Usually it is preferable to dispose the electrode around the marginal portions only of the heel, if placed in a high frequency field, might engender a harmful amount of heat. 'Ihe forepart and shank areas, on the other hand, are

preferably cement lasted, or stitched, to avoid or reduce the presence of metal in the bonding area.

When the shoe has a metal shank stiffener, then the electrode is preferably confined to the side margins of the shank portion of the bottom of the Y last, so as not to overlap the centrally disposed stiffener. Y Y

The electrode II instead of being a plate, can be a conductor of any other` suitable form, for example, a Wire mesh or grid (not shown) or a continuous wire which may be laid sinuously over any desired part ofthe last. It is fastened directly to the last in any suitable or desired manner as by adhesive, tacks, or screws, and the latter, if used, are countersunk or smoothed so as not to project into the dielectric space between the electrodes. The entire electrode may preferably be coated-or faced with a protective covering of lacquer, porcelain, enamel, or the like to prevent accidental formation of such projections through scratching or scarring,

The supply of electrical energy for the heating.

electrode can conveniently be led to the vicinity of the heel post of the press in which the shoe cementing operation occurs and, as shown in Fig. 1, can be led thence to the electrode. In that figure the shoe press heel post is designated I2 and has at its lower side an electrically conductive plug or jack I3' which may be mounted on the heel post or freely movable with respect thereto as preferred. This plug is in circuit by means of a conduit III with one side of the oscillating circuit, which is not illustrated, but which may be set up in any desired manner, for example as shown in my mentioned Patent No. 2,109,323. Plug I 3 has a downwardly extending pin I5 which fits snugly into electrical contact with the liner I5 of the conventional jack-pin hole provided in the heel portion of the last. This liner is of conductive metal. An electric conductor is provided between liner I5 and electrode II and may preferably take the form of a metallic pin or rivet I1. A

Instead of leading theelectric energy through the jack-pin hole it may be otherwise brought to the electrode, for example by a direct outside Wire, but thedescribed arrangement is much more convenient and lends itself readily to use in conjunction with existing types of shoe presses andV lasts. Wherrthe current is led directly to the jack or plug I3 beneath heel post I2 care must of course be taken that such post is suitably insulated with respect to the remainder of the circuit, which can be done by making the entire post of non-conductive material or by putting an insulating facing |48 on its under side.

In Figs. 2 and 4 means are shown for providing a hinged last with an electrode having different portions on different last sections, and with means for supplying energy to all of these electrode portions. Here the last II comprises a forepart section I9 and a heel section 2U, which are hinged about the pivot 2| for movement between broken and unbroken positions.

An electrode I II is provided on the under side of the last and may preferably, as illustrated, be of loop configuration extending around the marginal forepart and shank portions of the last bottom. The electrode is made in different portions corresponding with the different last sections, there being a forepart portion 22 and a rear or heel portion 23 respectively provided with means for making contact with each other when -the last is in unbroken condition. As best shown in Fig. 2, the electrode portion 22 has flanges 24 extending upwardlyV into the hinge joint opposite corresponding flanges 25 on opposed parts of the cone electrode portion 23. While these flanges may separate when the last is in broken condition, they will always be in rm abutting contact when the last is in operative unbroken condition within a shoe, and if desired may be given'a slight spring toward each other if the metal employed is amenable to tempering. The electrical energy is convenientlysupplie to electrode portion 23 through a conductive jack-pin hole liner IIB and a conducting pin or` rivet III, the lower end of which is anchored in a centrally disposed rearwardly extending tongue 26 on the electrode portion 23.

The electrode proper terminates approximately at the heel breast line designated 2l, thus leaving the entire heel seat area, except for the part adjacent tongue 26, uncovered by the electrode. A tack clenching plate 28 can be positioned around the marginal heel portion of the last bottom and is spaced or remote from the electrode. This clenching plate does notpartake of the heating functions of the electrode circuit and has no current therein save what possibly might Y be induced fromthe presence of the eld about the electrode, but the cleanching plate is sufciently remote to avoid any harmful heating at the tacked heel end of the shoe. A similar clenching plate 28 may be exposed on the bottom of the form of last shown in Fig. 1 and is similarly spaced or insulated from the electrode circuit. Y.

Current may be led to the electrode III yby means of a conductive heel post such as that shown in the Smith Patent 2,109,323 which as shown in Fig. 2 herein may comprise a block 29 of insulating material with a metallic contact plate 30 therebeneath in circuit with a conductive bolt 3| to which high frequency electrical energy is supplied. The top of the last can be provided with an electrical conductive contact plate`32 abutting plate 30 and contacting liner I I6. Preferably the last of Fig. 1 may also be provided with such a contact plate 32, thus adapting it more readily for use with a press having a contact plate type of heel post.

Various changes and departures from the illus-` trated embodiments of the invention may be I made without departing from its principles.

Thus the circuit to or between different electrode portions such as 22 and 23, while conveniently effected by means of `abutting flanges, may be maintained in other ways as, for example, by

separate wiring for each portion. Such wiring,

for example, could lead from one electrode section thru the last hinge pin to another section..

It will also be appreciated that the electrode can be made in `any desired configuration andcan be disposed on any part of the last adjacent which it is desired to set up a heating field. Thus the electrode could be disposed about the toe of the aardse? last for cooperation with another outside electrode for the purpose of heating box toes to dry them or to aid in molding them if they are of thermoplastic material. The heating field set up adjacent the electrode may be employed in cementing operations, either to fuse or make tacky a thermoplastic adhesive or to drive off solvent so as to speed the setting of an adhesive such as pyroxylin cement.

Since certain changes may be made in the above construction and different embodiments of the invention could be made without departing from the scope thereof, it is intended that al1 matter contained in the above description or `shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

It is also to be understood that the following claims are intended to cover all of the generic and specic features ofthe invention herein described, and all statements of the scope of the invention which, as a matter of language, might be said to fall therebetween.

Having described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A last for use in a shoemaking process wherein shoe parts are stuck together with an adhesive heated by a high frequency electrical eld, comprising a last body of electrically nonconductive material, a U-shaped metal clenching plate extending around the entire marginal heel seat portion of said last, but not over the central heel seat portion thereof, a metal electrode plate on the forepart and shank portions of said last bottom having a rearwardly extending tongue underlying the central heel seat portion of said last, said electrode plate and tongue being spaced from said clenching plate so as to be electrically insulated with respect thereto, said last having a jack-pin hole, and an electric conductor extending from said hole to said tongue through a passage forming an alined continuation of the jack-pin hole.

2. A last for use in a shoemaking process wherein parts of shoeshaving a tack or staple lasted heel seat are stuck together with an adhesive heated by a high frequency electrical eld, comprising a last body of electrically non-conductive material having a jack-pin hole, a metal high frequency electrode on the forepart and shank portions of said last bottom, the marginal portions of which terminate rearwardly approximately at the heel breast line, said electrode having a rearwardly extending centrally disposed tongue underlying said jack-pin hole but clearing the marginal lasting edge of the heel seat of said last, there being a passage forming a continuation of said hole extending to the last bottom, and electrical conductor in said passage connecting said tongue with the interior of said hole for access to a source of high frequency current.

JOI-IN FREDERICK SMITH.

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