GB2315664A

GB2315664A - Manufacture of footwear

Info

Publication number: GB2315664A
Application number: GB9715826A
Authority: GB
Inventors: Paul Harris; Colin Carter; Paul Thick; Neil Clarke; John Daine; Adrienne Leech
Original assignee: Clark C & J Int Ltd; C&J Clark International Ltd
Current assignee: Clark C & J Int Ltd; C&J Clark International Ltd
Priority date: 1996-07-26
Filing date: 1997-07-25
Publication date: 1998-02-11
Also published as: GB9715826D0; GB9615755D0

Abstract

A sole construction in which a separate heel portion (20) having a hollow (25) formed therein is attachable to a metal shank (10), which forms part of an insole, by means of a captive nut (30) and a screw (35). The head portion (31) of the captive nut sits within a slightly recessed seat formed around an aperture formed in the shank (10) and the screw (35) is driven through an aperture (26) formed in the base (21) of the heel portion (20). In this way, the heel portion (20) may be securely attached to the insole after a flexible material covering, such as soft attractive leather, has been placed over the upper surface of the insole and attached to the underside surface thereof. Furthermore, replacement heels may easily be fitted to the shoe.

Description

Manufacture of footwear The present invention relates to the manufacture of footwear and in particular to a shoe construction having a separate heel and a method of constructing such a shoe.

It is known to produce shoes having a separate heel portion and there are a variety of known ways of attaching the heel portion to the insole of such a shoe. For example, conventional methods of attaching a heel portion include the use of adhesives placed between the heel portion and the insole of the shoe, and the use of nails, screws or staples driven through the insole of the shoe into the heel portion, the exposed heads of the nails, screws or staples subsequently being covered with, for example, an inner sock. It is also possible to use a number of such methods in conjunction with one another.

The key determinant of which method should be used is the leverage expected, which arises from the geometry of the design, and the way in which this interacts with the components of the shoe. Clearly a slender ladies' heel of 50 to 75 millimetres height acts as a substantial lever when forces are applied to the ground contact point, whereas a large contact area, 12mm high, men's heel will act in a totally different way.

Shoemaking engineers select the method of attachment to ensure that the final assembly is fit for the purpose. Guidelines exist for the pattern of nail placement, the strength of the inner sole components, and the position of selected reinforcement relative to the other constituent parts of the assembly. These are all well known to those skilled in the art, and it is not the intention of this invention to redefine these guidelines.

There are, however, certain shoe constructions where it is not possible to provide a strong attachment between the insole and the heel portion using conventional methods because of, for example, aesthetic considerations. An example of this is the 'Californian' construction, which differs from some other methods in that the inner sock is sewn in place with respect to the upper, before the upper is formed on the last. Thus any decoration and cushioning in the heel region must be in place before the heel portion is attached to the insole. In this and similar cases, the use of nails driven from the inside of the shoe to secure the heel portion is impossible. For this reason, Californian shoes and sandals have always been confined to low heel designs where sufficient adhesion between the heel portion and the insole can be achieved to ensure prolonged, secure attachment.

In a similar way, inner soles may be constructed for open heeled products like sandals and mules, with for example padded covers through which it is inappropriate to nail or screw.

The present invention seeks to provide a shoe construction having a separate heel portion and a method of constructing such a shoe which overcomes one or more of the disadvantages associated with the conventional shoe constructions described above.

According to a first aspect of the present invention there is provided a shoe construction comprising a substantially rigid insole having an upper surface, an underside surface and engagement means formed therein or attached thereto; a flexible material covering which extends over the upper surface of said insole; a separate heel portion; and mechanical attachment means, for engagement with the engagement means from the underside of the insole, for mechanically securing said heel portion to the underside of said insole.

Preferably the flexible material covering is secured to the underside of said insole. This may conveniently by done using a resin or other form of adhesion.

The engagement means may take the form of a captive nut trapped within the insole, in which case the mechanical attachment means may conveniently be a screw. It is advantageous if the heel portion is hollow, since then the mechanical attachment means may be operated discretely from within the hollow. It is also advantageous if the attachment means is releasable since then heel portions may be easily exchanged or replaced.

The insole preferably includes a metal member attached on its underside surface and acting to trap, between itself and the underside surface of the insole, said engagement means. The metal member may comprise the metal reinforcing shank commonly found in certain types of shoe construction.

In a currently preferred embodiment, the engagement means is formed by a captive nut comprising a tubular section which protrudes downwardly through an aperture formed in the shank, and a radially outwardly extending hexagonal flange which abuts the upper surface of the shank around the aperture.

Although it is advantageous to use a captive nut as the engagement means, the engagement means could, of course, simply be a surface against which a flange, or other protrusion, of the attachment means may bear, such as, for example, the surface of the shank surrounding an aperture in the shank.

The flexible material covering may take the form of a flexible inner sock to which a separate strip of backing material has been sewn, or otherwise attached, the inner sock resting on top of the insole in registry therewith, and the backing material extending around the edge of the insole and being secured to the underside surface thereof to hold the insole cover in place.

According to a second aspect of the present invention there is provided a method of constructing a shoe including the steps of providing a substantially rigid insole having an upper surface, an underside surface and engagement means formed therein or attached thereto; covering the upper surface of said insole with a flexible material covering; and subsequently securing a separate heel portion to said underside surface by mechanical attachment means for engagement with the engagement means from the underside of the insole.

Preferably the method further comprises the step of securing said flexible material covering to the underside surface of said insole.

Preferably, said heel portion is hollow and said mechanical attachment means is driven through the base of said heel portion, or through an aperture formed in the base of said heel portion for receiving said mechanical attachment means, whereby said mechanical attachment means is operable from within the hollow of said heel portion.

In order to maintain the heel portion in a fixed orientation with respect to the insole, it may be advantageous to use adhesive between the base of the heel portion and the underside surface of the insole in conjunction with the mechanical attachment means.

The principal advantage of the present invention is that a much larger variety of separate heel designs may be used in conjunction with shoe constructions which were formerly limited to having only low separate heel designs. A further advantage of the present invention is that it is possible to have shoe constructions in which the heel portion may be easily replaced or exchanged.

In order that the present invention may be better understood embodiments thereof will now be described by way of example only and with reference to the accompanying drawings in which: Figure 1 is a diagrammatical cross-sectional view showing a heel, shank and attachment arrangement according to the present invention; Figure 2 is a perspective view of an assembled embodiment of the present invention; Figure 3 is an underneath perspective view of the embodiment shown in Figure 2; and Figure 4 is an enlarged perspective view of the captive nut, the screw and part of the shank shown in Figures 2 and 3.

As shown in the Figures, the basic elements of one preferred type of shoe construction are a shank 10, a heel portion 20 and a captive nut 30 and screw 35 arrangement. The heel portion 20 has a base 21 and a top end 22. The heel portion 20 is hollow, the hollow 25 of the heel portion extending through the top end 22 such that the hollow is accessible. An aperture 26 is formed in the base 21 of the heel portion 20 and enables a screw 35 to be driven therethrough.

The shank 10 is made of metal and is relatively stiff so as to act as a reinforcing means for the inner sole of a completed shoe. An aperture 12 is formed in the shank 10 which receives the captive nut 30. Although it cannot be clearly seen from the Figures, the aperture 12 is formed in a slightly recessed portion of the shank 10 which forms a seat for the captive nut 30.

This allows the upper surface of the captive nut 30 to be approximately flush with the upper surface of the shank 10. Figures 2 and 4 also show small apertures 18,19 which are used in riveting the shank 10 to the backer (not shown) of a completed shoe.

As is shown in Figure 4, the captive nut 30 has an axially extending, cylindrical, tubular portion 32 extending downwardly away from a radially outwardly extending flange 31 having a hexagonal outer periphery.

Although it is again not very clear from the drawings, the recess formed around the aperture 12 in the shank 10 has a hexagonal inner periphery corresponding to the outer periphery of the flange 31 such that when the captive nut 30 is seated in the recess it is not able to rotate relative to the shank 10. The internal surface of the captive nut 30 is threaded to compliment the thread of the screw 35 which engages with the captive nut 30.

In order to construct a complete shoe from the components shown in the Figures, the captive nut 30 is firstly placed into the seat formed in the shank 10. Then the inner sole is built up in a conventional manner by, for example, riveting a relatively stiff backer and a slightly more flexible forepart to the shank 10. A layer of cushioning foam is then normally placed on top of the backer and forepart.

Having reached this stage in constructing the inner sole one could simply wrap an insole cover (made for example of an attractive and soft leather) over the top of the cushioning foam, and secure the insole cover to the underside surface of the inner sole (i.e. the backer and forepart) to be left with a completed inner sole which can be used in a variety of different shoe designs such as sandals and mules and to which a variety of different types of heel may be attached. Alternatively, to make a sandal according to the 'Californian' construction, rather than simply covering the cushioning foam with a cover, an inner sock whose shape corresponds to the shape of the inner sole is sewn to the upper of the shoe and also to a strip of backing material.

The sewing operation is conveniently done off the last, and then the inner sole is brought to meet the combined inner sock and upper in place on the last, and the backing material is adhered to the underside surface of the inner sole.

The seam between the inner sock and the backing material provides a very attractive finish to the shoe.

Finally, an outer sole is adhered to the underside surface of the fore part of the inner sole, and the heel portion is secured to the shank by means of the screw 35 and the captive nut 30. In order to protect the heel portion from scuffing and to provide an attractive finish, a toppiece (not shown) is adhered to the top of the heel portion 20. The toppiece covers the entrance to the hollow 25 and may conveniently be made from the same material as the outer sole. In this arrangement the outer sole is conveniently tucked under the base 21 of the heel portion 20. However, an alternative arrangement of the heel portion 20 and outer sole, is firstly to attach the heel portion 20 to the inner sole, and then to adhere the outer sole to the underside of the heel and inner sole combination; this works particularly well with heel portions having a shallow sloping front facing edge.

Claims

1. A shoe construction comprising a substantially rigid insole having an upper surface, an underside surface and engagement means formed therein or attached thereto; a flexible material covering which extends over the upper surface of said insole; a separate heel portion; and mechanical attachment means, for engagement with the engagement means from the underside of the insole, for mechanically securing said heel portion to the underside of said insole.

2. A shoe construction as claimed in claim 1 wherein the flexible material covering is attached to the underside of said insole.

3. A shoe construction as claimed in either one of the preceding claims wherein the flexible material covering is attached to the insole using a form of adhesion.

4. A shoe construction as claimed in any one of the preceding claims wherein the engagement means comprises a captive nut trapped within the insole, and said mechanical attachment means comprises a screw.

5. A shoe construction as claimed in any one of the preceding claims wherein said heel portion has a hollow formed therein, and wherein said mechanical attachment means may be operated from within the hollow of said heel portion.

6. A shoe construction as claimed in any one of the preceding claims wherein said attachment means is releasable from and re-attachable to the engagement means.

7. A shoe construction as claimed in any one of the preceding claims wherein said inner sole comprises an inner sole fabric portion and a metal member attached to the underside surface of the inner sole fabric portion and wherein the engagement means is attached to or formed as an integral part of the metal member.

8. A shoe construction as claimed in claim 7 wherein the metal member has an aperture formed therein and wherein the engagement means is formed by said aperture.

9. A shoe construction as claimed in claim 7 wherein the metal member has an aperture formed therein through which a part of the engagement means projects, and wherein another part of the engagement means is trapped between the metal member and the underside surface of the inner sole fabric portion.

10. A shoe construction as claimed in claim 9 wherein the engagement means is a captive nut and wherein a shallow, shaped recess is formed around the aperture for engaging the head of the captive nut in order to prevent relative rotation between the captive nut and the metal member.

11. A shoe construction as claimed in any one of the preceding claims wherein the flexible material covering comprises a flexible inner sock to which a separate strip of backing material has been attached, wherein the inner sock rests on top of the insole in registry therewith and wherein the backing material extends around the edge of the insole and is secured to the underside surface thereof.

12. A shoe construction as claimed in any one of the preceding claims further comprising adhesion means between the heel portion and the underside surface of the insole.

13. A method of constructing a shoe including the steps of providing a substantially rigid insole having an upper surface, an underside surface and engagement means formed therein or attached thereto; covering the upper surface of said insole with a flexible material covering; and subsequently securing a separate heel portion to said underside surface by mechanical attachment means for engagement with the engagement means from the underside of the insole.

14. A method as claimed in claim 13 wherein the step of covering the upper surface of said insole further comprises securing the flexible material covering to the underside surface of said insole.

15. A method as claimed in either one of the preceding claims wherein said heel portion has a hollow formed therein and wherein the step of securing the heel portion to the underside surface of said insole comprises driving the mechanical attachment means through the base of said heel portion, or through an aperture formed in the base of said heel portion, said mechanical attachment means being operable within the hollow of said heel portion.