US3626532A

US3626532A - Shoemaking methods

Info

Publication number: US3626532A
Application number: US68250A
Authority: US
Inventors: Frank R Smith
Original assignee: USM Corp
Current assignee: USM Corp
Priority date: 1969-09-05
Filing date: 1970-08-31
Publication date: 1971-12-14
Anticipated expiration: 1988-12-14
Also published as: ZA706075B; GB1262204A

Abstract

A METHOD OF MAKING SHOES IN WHICH THE MARGIN OF A LASTED SHOE UPPER IS APPLIED TO MOLTEN THERMOPLASTIC ADHESIVE ON THE BOTTOM OF A LAST AND, AFTER THE ADHESIVE SETS TO FORM A LASTED SHOE UNIT, AND OUTSOLE MEMBER IS APPLIED.

Description

Dec. 14, 1971 F. R. SMITH 3,626,532

SHOEMAKING METHODS Filed Aug. 31, 1970 2 Sheets-Sheot 1 Fl gl ln'uenior' F/"mk fRSmz'zh By his Aftor'ney 1971 F. R. SMITH SHOEMAKING mmnons 2 Sheets-Sheet 2 Filed Aug. 31, 1970 United States Patent 3,626,532 SHOEMAKIN G METHODS Frank R. Smith, Leicester, England, assignor to USM Corporation, Boston, Mass. Filed Aug. 31, 1970, Ser. No. 68,250 Claims priority, application Great Britain, Sept. 5, 1969, 44,053/69 Int. Cl. A43d 21/00 US. Cl. 12-142 F 4 Claims ABSTRACT OF THE DISCLOSURE A method of making shoes in which the margin of a lasted shoe upper is applied to molten thermoplastic adhesive on the bottom of a last and, after the adhesive sets to form a lasted shoe unit, an outsole member is applied.

BACKGROUND OF THE INVENTION Of the various components which are assembled in the course of manufacture of a shoe, not the least costly is the insole. The requirements of a satisfactory insole are that it shall be sufiiciently flexible in the forepart to allow for natural bending of the foot at the ball region and yet be rigid enough to withstand the stresses of a lasting operation. The heel end of an insole is not required to be flexible and generally must be rigid enough to support a stiffening component or shank piece and to receive the heel when attached to the shoe at a later stage in the manufacture. To meet these requirements, some manufacturers have been using two-part insoles, the heel ends being of insole board and the forepart of a lighter material, flexible in the direction of the bending action of the foot. Whatever insole is used, however, certain difficulties arise in obtaining precise alignment of the insole with the edge of the last bottom even if the insole is accurately cut to the correct size. In practice, the fit is often not quite accurate, and even slight inaccuracies of fit can mar the appearance of the feather line or bottom edge of the finished shoe above the outsole. Difficulties are also encountered where it is required to form an outsole directly on to the lasted shoe by a molding process, for example, by injection molding, since the mold cavity which is in the shape of the required outsole is enclosed partly by the underside of the lasted shoe, mold members defining the remainder of the cavity being in contact with the shoe around its feather line. Where this feather line is not uniform around the shoe, the injected plastics material is likely to spue, thus marring the finished shoe. Where the mold members include welt plates which butt against the feather line, these plates are liable to exert sufiicient pressure on the edges of the insole, particularly in the forepart region, to cause it to bow away from the last bottom and where the pressures in the mold cavity are not sufiicient to iron out this bow, then the resulting shoe will be faulty.

The invention provides, among its several features, a method of lasting shoes comprising the steps of positioning an upper about a last; applying thermoplastic adhesive to marginal portions of the last bottom; forming a lasted unit by laying the margin of the upper against said marginal portions of the last bottom to which the adhesive is applied, said adhesive acting to consolidate the marginal portions of the upper in a wiped condition; and providing the lasted unit with an outsole member, the arrangement being such that any adhesion of the marginal portions of the upper to the last bottom is impermanent.

In most types of shoes the provision of a shank member is needed to give the required rigidity to the shank and heel end regions of the shoe bottom. In a shoe which has been lasted in the forepart region using a method according to the present invention, the shank member 3,625,532 Patented Dec. 14, 1971 "ice may be incorporated by being secured to a part-insole which does not extend into the forepart region of the shoe but provides support for the shank member in the shank and heel end regions. Where such a part-insole is provided, it may be found convenient to last the shoe by a conventional cement lasting process in the shank and heel end regions whereby the margin of the upper in those regions is secured to marginal portions of the partinsole. The partially lasted shoe may then be subjected to a forepart lasting operation using a method according to the present invention. An outsole member in the form of a preformed shoe bottom unit may then be secured by means of adhesive to the bottom of the lasted unit, the wiped margins having been roughed in the usual way. If it isrequired to provide an outsole member by molding plastics material on to the bottom of the lasted unit, the shank may be positioned within the mold cavity by suitable means.

There will now be given, with reference to the accompanying drawings, a detailed description of a method, illustrative of the invention, of making a shoe having a part-insole extending over the waist and heel end regions of said shoe. It will be understood that the illustrative method is selected for description merely by Way of exemplification of the invention and not by way of limitation thereof.

In the accompanying drawings:

FIG. 1 is a view of the underside of an unfinished shoe which has been constructed according to the illustrative method;

FIG. 2 is a diagrammatic view of a step in the illustrative method;

FIG. 3 is a section taken on line III-III of FIG. 1;

FIG. 4 is an enlarged view of a portion of FIG. 3, and

FIG. 5 shows a section through a completed shoe.

A part-insole 2 bearing a shank member 4 is positioned on a last 6 so that a metal plate 8 secured to the bottom of the last is covered by the part-insole in the shank and heel end regions of the last bottom and is exposed in the forepart region. The last may be formed of wood or plastic material with a metal bottom plate extending at least over themarginal portions of the last bottom in the regions where there is no insole. Where an outsole member is to be directly molded on to the shoe, the last may be a metal foot form. An upper 10 is placed around the last so that marginal portions of the upper project beyond the last bottom in the shank and heel end regions and the shoe is then lasted in those regions by well-known operations. The heel seat lasting operation can be performed on a conventional tack seat lasting machine, and the shank lasting can be accomplished on any suitable machine. A combined heel seat and shank lasting operation, if preferred, may be performed on machines commonly available for this purpose.

The forepart of the upper is then positioned for lasting as shown in FIG. 2. The lasting operation may be carried out on any suitable forepart lasting machine. In such machines, grippers, diagrammatically represented at 12, grasp the marginal portions of the upper and pull the upper taut about the last. A continuous bead of molten adhesive 14 is then applied to marginal portions of the forepart of the last bottom. The marginal portions of the upper are then wiped by wiping means (not shown) against the last bottom and the still molten adhesive flows between the folds and pleats of the marginal portions of the upper before it sets in a firm band which adheres to the marginal portions of the upper, thus consolidating them in the wiped condition. The adhesive, which is applied to the last bottom in order to consolidate the upper, may be one which is capable, while molten, of

flowing between the folds and pleats of the lasted marginal portions of the upper but will quickly set to consolidate the marginal portions firmly in the wiped condition. One type of adhesive which may be used is a polyester cement which has the added advantage that no release agent is required to be applied to the metal last bottom to prevent adhesion of the cement thereto. Where adhesion to an extent which will hinder slipping the last from the completed shoe is likely, because of the type of adhesive used or of the material of the last bottom, then a suitable release agent will be required.

If required to enhance the bond with an outsole unit, the lasted marginal portions of the upper may be roughed by any conventional roughing machine and would then have the appearance shown in FIG. 1. The shoe is then ready to receive an outsole member 18. Where the outsole member is to be molded on to the shoe, an interlayer '16 may be placed on the exposed last bottom to prevent adhesion of the injected plastics material to the last bottom. Molding takes place in a conventional manner and the last is then slipped from the shoe. FIG. 5 shows the finished shoe before insertion of a suitable lining. It can be seen that the inside surface of the shoe bottom is substantially smooth and even, requiring only a lining such as an insock to complete the shoe which by its construction is particularly flexible in wear.

It will be seen in FIG. 2 that the upper 10 can be provided with a toe reinforcement which may be of thermoplastic material. The edge of the reinforcement which is visible in that figure will be wiped in as part of the marginal portions of the upper during the forepart lasting operation. Because the reinforcement is in a flaccid condition as required during this operation, it will fold and pleat with the marginal portions of the upper as they are wiped in. On cooling, the reinforcement returns to a relatively rigid state and generally enhances the consolidation effect of the bead 14 of adhesive at the extreme toe end of the shoe.

The part-insole 2 shown in FIGS. 1, 2 and 5 may be specially constructed as a multi-layered assembly, the shank member being sandwiched between two layers thereof. It will be especially convenient if at least the lower layer, i.e., that furthest from the last bottom when assembled, is of a material which well receives a cement lasting operation. The upper layer may conveniently be of insole board material. It should be apparent that the part-insole could be omitted entirely and the heel and shank portions of the shoe could be lasted and consolidated before outsole attachment by adhesive alone in the same manner as the forepart region. If shank reinforcement is desired, a shank member may be supported by a spider of plastics material or be temporarily secured to the last bottom by other means. Alternatively, a shank member can be positioned in a mold cavity where the outsole unit is to be injection molded directly onto the consolidated upper.

Having thus described my invention, what I claim as novel and desire to secure by Letters Patent of the United States is:

1. A method of making shoes including the steps of:

assembling an upper On a last;

applying molten thermoplastic adhesive to marginal portions of the last bottom;

shaping the upper about the last and laying the margin of the upper inwardly over the last bottom on said molten adhesive;

allowing the adhesive to set to hold the upper in consolidated shaped condition to form a lasted shoe unit, and

applying an outsole member to the bottom of the shoe unit.

2. A method according to claim 1 in which said adhesive is applied to the forepart of the last bottom and the heelward portion of the upper margin is secured to a part-insole placed on the heelward portion of the last bottom.

3. A method according to claim 1 in which the step of applying the outsole member includes forming said member by injection molding directly on the bottom of the lasted shoe unit.

4. A method according to claim 1 having the addi- References Cited UNITED STATES PATENTS 2/1958 Stritter 12-142 F 12/1960 Stix 12-145 PATRICK D. LAWSON, Primary Examiner US. Cl. X.R. 12145