GB2027581A

GB2027581A - A method of manufacturing footwear comprising a sole made of injectable material, and a die for working the method

Info

Publication number: GB2027581A
Application number: GB7832716A
Authority: GB
Original assignee: NOVA Srl A
Current assignee: NOVA Srl A
Priority date: 1978-08-09
Filing date: 1978-08-09
Publication date: 1980-02-27

Abstract

A footwear upper is mounted on a last, the lower part of which is clamped in a die having jaws forming a chamber having the same shape and dimensions as the sole near the bottom surface of the last, after which hardenable plastics or elastomeric material is injected into the chamber so as to form the sole and surround that part of the upper which covers the lower surface of the last. Figure 5 illustrates the invention which comprises forming grooves 11 and 12 in the lower surface of the last which cause injected material to form beads integral with the shoe sole. <IMAGE>

Description

SPECIFICATION A method of manufacturing footwear comprising a sole made of injectable material, and a die for working the method The invention relates to methods of manufacturing footwear of the kind wherein the upper is mounted on a last, the lower part of which is clamped in a die having jaws forming a chamber having the same shape and dimensions as the sole near the bottom surface of the last, after which hardenable plastics or elastomeric material is injected into the chamber so as to form the sole and surround that part of the upper which covers the lower surface of the last.

The invention also relates to an improved die for manufacturing footwear having a sole directly secured to the upper, the die comprising a bottom, two jaws on the bottom and movable with respect thereto in order to define the die cavity, and a last disposed above the jaws so as to close the die cavity, the last bearing the upper to be joined to the sole.

In the prior art, footwear is manufactured by constructing the sole when directly secured to the underlying part of the upper. Next, an insole made of a relatively flexible sheet is inserted in the footwear and stuck to the inside thereof.

In the case of footwear comprising anatomically or orthopaedically shaped insoles, the insoles are formed in a die in an operation separate from the sole-moulding operation; they are then covered with a sheet of leather or plastics, inserted in the footwear and secured by adhesion. This prior-art method is very expensive, particularly when it is desired to manufacture cheap footwear.

An object of the invention is to provide a method and die wherein the sole is formed simultaneously with a foot-supporting structure integral with the sole, so that there is no need to insert an insole in the footwear, or alternatively the material required for the insole is reduced to a minimum. To this end, the invention provides a method of the aforementioned kind characterised in that it comprises the following additional steps: a) Forming a number of grooves in the lower surface of the last, and b) Connecting the die chamber to the grooves so that, when the injected material hardens, a number of beads integral with the sole are formed at the grooves, and the part of the upper covering the bottom surface of the last is secured between the beads and the sole.

The aforementioned method can be used to obtain footwear which is very strong and rugged, owing to the fact that the sole is formed simultaneously with the foot-supporting structure, and as a result the intervening part of the upper is embedded between the sole and the footsupporting structure.

The method can also be used, when required, to obtain foot-supporting structures having certain anatomical shapes. The structures are made up of a number of beads and leave cavities between each pair of adjacent beads, so that the feet can perspire more easily.

The invention will now be described with reference to a preferred embodiment illustrated in the accompanying drawings, which are given by way of non-limitative example. In the drawings: Figure 1 is a partly cut-away view in elevation of footwear such as a sandal, made by the method according to the invention; Figures 2, 3 and 4 illustrate successive steps in the manufacture of the footwear in Figure 1, and Figures 5, 6 and 7 are cross-sections along lines V-V, VI--VI and VIl-VIl respectively in Figures 2, 3 and 4.

Reference 1 denotes footwear such as a sandal open at the tip and heel. The footwear is obtained by the method according to the invention, as follows: An upper 2 is mounted on a last 10 and extends on the last, without covering cap 1 Oa and heel 1 or. The bottom surface of last 10 has a number of longitudinal grooves 11 extending along its entire length. The surface is also formed with a surrounding groove 12 disposed near the free edge of the surface and extending all round it.

As shown in Figure 2, last 10 and the associated upper 2 are disposed above a die 3 for forming the sole of the footwear. Die 3 comprises a stationary part 4 adjacent the lower surface of last 10, and two lateral jaws 5 each having an upper lip 6. Last 10 is lowered to its end position (Figure 3), during which time jaws 5 are brought to the spaced-apart position shown by chain lines in Figure 5. Next, jaws 5 close and grip the bottom part of last 1-0 as shown in Figure 6. Consequently, last 10 and the stationary part 4 of the die form a chamber 7 having the same shape and dimensions as the sole. The part of upper 2a which covers the bottom surface of the last ieaves an uncovered front portion 9a and an uncovered rear portion Sb corresponding to the cap 1 Oa and heel 1 Ob respectively of last 10.The uncovered regions form apertures through which grooves 11, 1 2 communicate with the underlying chamber 7.

Hardenable thermoplastic or elastomeric material is supplied to chamber 7 through a duct 8 formed in die 3. The material travels through apertures 9a and 9b to grooves 11 and 12 and fills them as shown in Figure 4. In addition, the bottom part 2a of upper 2 has a number of apertures 13 which, during the last-mentioned step, are also filled with injected material. After hardening, therefore, the material forms a sole 14 underneath part 2a of upper 2, and beads 1 5 are formed above the sole, opposite grooves 1 the number of beads being equal to the number of grooves and the beads being side by side and extending longitudinally all the way along the bottom surface of the last. In addition, a surrounding bead 1 6 forms to match the surrounding groove 12 and, together with beads 15, forms a structure constituting a bearing base for the feet. Projections 1 7 form in part 2a of the last, corresponding to apertures 13, the number of projections being equal to the number of apertures and the projections acting as securing pins for attaching part 2a to the underlying sole and to the beads above.

Of course, without altering the principle of the invention, the embodiments and details of execution can be widely varied from those described and illustrated by way of example, without thereby departing from the scope of the invention.

Claims

1. A method of manufacturing footwear of the kind wherein the upper is mounted on a last, the lower part ofwhich is clamped in a die having jaws forming a chamber having the same shape and dimensions as the sole near the bottom surface of the last, after which hardenable plastics or elastomeric material is injected into the chamber so as to form the sole and surround that part of the upper which covers the lower surface of the last, wherein a plurality of grooves are formed in the lower surface of the last, and wherein as an additional step the die chamber is connected to the grooves so that, when the injected material hardens, a number of beads integral with the sole form at the grooves and the part of the upper covering the bottom surface of the last is secured between the beads and the sole.

2. A method according to Claim 1 wherein the die chamber is connected to the grooves on the bottom surface of the last by forming apertures in that part of the upper which covers the bottom surface of the last, the apertures being positioned and dimensioned so that the injected material can flow into all the aforementioned grooves.

3. A method according to Claim 2 wherein the part of the upper covering the bottom surface of the last is formed with a number of small apertures adapted to be filled with injected material so as to secure the upper to the sole on one side and to the beads on the other side.

4. A method according to Claims 1 to 4, applied to footwear such as a sandal open at the cap and heel, wherein the aforementioned grooves are longitudinal and an additional groove extends all round the bottom surface.

5. A die for manufacturing footwear according to the method in Claims 1 to 4, wherein the last on which the upper is mounted has a plurality of grooves in its bottom surface facing the die cavity.

6. A die according to Claim 5, wherein the grooves extend from the tip to the heel and are open at their ends.

7. A die according to Claims 5 and 6, wherein the ends of the grooves open into a peripheral channel extending all the way round the bottom surface of the last.

8. A method as claimed in Claim 1 substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

9. A die as claimed in Claim 5 substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

10. A shoe substantially as described with reference to and as shown in Figure 1 of the accompanying drawings.