US2021835A - Molded leather article process - Google Patents

Description

Nev. 19, 1935. J. v. CRITCHLEY 1,

MOLDED LEATHER ARTICLE PROCESS Filed June 6, 1933 2:4 I r I 1% Fi .4

?atented Nov. 19, 1935 UNITED STATES PATENT OFFICE MOLDED LEATHER ARTICLE PROCESS Application June 6, 1933, Serial No. 674,537

4 Claims.

The present invention is concerned with the production of improved articles of leather, and more particularly with the production of leather lifts or top lifts for boots and. shoes.

I have discovered that by subjecting a leather blank having a shape and dimensions approximating the finished article to suitable compression in a mold, I can reduce the blank to an exact shape and size and completely finish the external surfaces, both the natural grain and flesh surfaces appearing at opposite sides of the blank and the cut edge which is normally rough and somewhat irregular. I have found that this method, although not limited in its application to this type of article, is nevertheless particularly applicable to the production of leather top lifts for boots and shoes. Normally these lifts are produced in blank form, secured to a supporting heel structure and then cut and finished to size and shape upon the shoe. This method is relatively slow and arduous, and leaves no guarantee as to either uniformity of appearance or dimension.

According to the present invention, I provide a blank in proper temper cut to generally the proper contour of the heel lift from sheet leather. This blank is slightly larger than the finished form of the molded lift. Thereafter the blank is assembled in a mold cavity which may have tapering walls, and is forced downwardly into the cavity under heavy pressure. The shaping of the blank to the cavity produces an exact conformation of the finished product, the leather fibres apparently fiowing in a manner to produce a finished article which is actually smaller and thicker than the blank at the outset. For the effectual carrying out of this operation the temper of the blank and subsequent reduction in.

volume should both be controlled in order to insure best results.

In the particular embodiment of the invention with which the illustrated application is concerned, coincidentally with the molding of the blank I attach thereto a post, by virtue of which the finished top lift may be readily attached to or detached from a heel base through the provision of a cooperating socket assembled in the base. It will be evident that with my improved method, the top lift is finished accurately and attractively to exact dimensions both as to contour and with respect to the location of the holding post, and by virtue of this accurate sizing base corresponds in contour and dimensions to that of the blank.

Although my molding operation may besuccessfull-y employed upon blanks produced by different methods, nevertheless I have found that in the production .of top lifts and articles of like character it is desirable to operate upon a blank having an accurately cut edge portion with the sides approximately vertical with respect to opposite faces of the blank. This type of blank 10 insures that the subsequent molding operation will completely size the entire blank and finish the surfaces without leaving any vestige of the raw edge of the blank remaining at the completion of the molding.

In .the accompanying drawing illustrating the preferred formof the invention, Fig. 1 represents a view .in section of a blank preliminary to subjection to .the molding operation and attachment of the post; .Fig. 2 is a similar View of the top lift at the completion of the operation; Figs. 3 and 4 are plan views of the blank at the commencement .of the operation .and the completed .top lift; Fig. 5 is a sectional view of a top lift subjected to the operation without attachment .of the post, illustrating the concave bottom and beveled edge; and .Fig. 6 is a view illustrating the manner .in which the top lift is detachab-ly secured to a heel base.

Referring to the drawing, the heel blank indicated at it) is first assembled within the cavity E2 of a mold member M, the blank, as indicated, resting upon the prongs of a post it which is mounted in a block I8 in .the mold. Cooperating with the cavity portion of the mold is a plunger 20, which upon its entering movement engages with the blank and forces the latter to the bottom of the mold cavity as indicated in Fig. 2, at the same time engaging and clinching the prongs 22 within the top lift. This molding operation not only sizes and accurately forms the top lift, but in addition the tapering walls of the mold cavity l2 tend to center and gradually assert an increasing pressure upon the blank as it is forced into the mold cavity by the cooperating plunger.

As indicated particularly in the drawing, the bottom portion of the mold cavity is slightly convex at 24 to similarly concave the bottom of the finished top lift. In addition, the Walls of the cavity are provided with a circumferential groove .30, located adjacent the top portion of the fin- 'ished lift and designed to cause the finished lift to be forced thereinto at this portion to provide a beading therearound. The bottom face of the plunger 34 is provided with a downwardly projecting and beveled rim 36, which imparts a corresponding bevel to the tread face of the lift, this beveled tread face in conjunction with the surrounding bead providing an attractive finish for the lift which measurably enhances its appearance.

When subjected to this operation, which may be termed a sizing, molding or finishing operation, the blank is converted into a finished lift with its tread face and side edges accurately sized, and with an attractive finished surface throughout the exposed area. It will furthermore be recognized that this sizing, in conjunction with the assembling of the post, accurately locates the finished lift with respect to the securing post, and thus insures similarly accurate register within a heel base in which the post has been properly located. If so desired, finish stains and waxes can be applied to the blank before molding and forced into the finishedlift through the action of the mold cavity.

In order to obtain the desirable molding and finish of top lifts and similar articles, I have determined that the blank should have a moisture content of 18% to approximately. Furthermore, the reduction in volume for top lifts will range from 7% to 13% approximately for the purpose of securing the desired ultimate finish upon the article. In this connection, although the type of press in which the operation is carried out forms no part of the present invention, it should be understood that a definite and predetermined pressure is exerted upon the blank through the plunger 20, regardless of variations in thickness. This pressure may be obtained hydraulically or through the interposition of a spring, the mechanism in either case intended to exert a uniform and predictable pressure.

The edge of the blank receives its finish from the pressure of the surrounding walls of the mold cavity to which is imparted a smooth, lustrous finish for properly plating the edge surface in contact therewith.

It will be evident to those skilled in the art that although the present invention is particularly concerned with the production of molded top lifts or the like, nevertheless it is applicable to other molded articles of leather where a desirable sizing and finishing of exposed surfaces is to be obtained, and accordingly the invention is not limited except as confined by the claims to top lifts for boots and shoes.

What is claimed is:

1. The method of forming articles of leather which consists in producing a blank conforming generally to the desired finished form of the article and larger than the article in certain di- 5 mensions, assembling an attaching post in predetermined relation to the blank, and subsequently reducing the blank in temper to an exact shape and size by forcing the blank under heavy pressure into a tapering and non-separable mold 1 cavity which engages the cut edges of the blank and reduces it to a final shape of reduced volume in exact conformity with the mold cavity and simultaneously connecting the attaching post in permanent relation to the finished blank. 15

2. The method of forming articles of leather which. consists in producing a top lift blank conforming generally to the desired finished form of the top lift and larger in certain dimensions, assembling Within a mold cavity an attaching 20 post for the top lift, and subsequently reducing the blank in temper to an exact shape and size in the mold cavity and simultaneously connecting with the blank the assembled post through the pressure exertedby forcing the blank into the cavity to produce a top lift of predetermined dimensions With the post connected thereto in a definite relation.

3. The method of forming leather top lifts which consists in producing a blank conforming generally to the desired contour of the top lift and larger in outline, subsequently reducing the top lift blank in temper to an exact shape and size with a completely finished edge extending thereabout by forcing the blank under heavy pressure into a tapering and non-separable mold cavity engaging the blank throughout its entire peripheral edge, and surface-finishing the complete edge through molding contact therewith.

l. The method of forming leather top lifts which consists in producing a blank conforming generally to the desired contour of the top lift and larger in outline, applying finish material to the edge of the blank, subsequently reducing the top lift blank in temper to an exact shape and size with a completely finished edge extending thereabout by forcing the blank under heavy pressure into a tapering and non-separable mold cavity engaging the blank throughout its entire peripheral edge, and burnishing the finish material into the edge of the blank through contact with the mold cavity.

JAMES VERNER CRITCHLEY.

Images