EP0111256A1

EP0111256A1 - Inner sole for footwear

Info

Publication number: EP0111256A1
Application number: EP19830112046
Authority: EP
Inventors: Giancarlo Tanzi
Original assignee: ASOLO SpA
Current assignee: ASOLO SpA
Priority date: 1982-12-09
Filing date: 1983-12-01
Publication date: 1984-06-20
Also published as: EP0111256B1; DE3376289D1; IT8259342V0; GB8314472D0; GB2131277A

Abstract

An accurately shaped, durable inner sole (1) is formed by injection _'moulding of synthetic resin and has areas of differing thickness and pliability depending on the foot region to be supported and the type of footwear to which the inner sole (1) is intended to be applied. A peripheral band of diminished thickness, e.g. in the form of a groove (2) in the upper surface, may be provided to facilitate stitching of the inner sole into an item of footwear. Also a spring may be attached on the underside of the inner sole to make same sturdier and more resilient.

Description

This invention relates to an inner sole suitable for a wide range of footwear types.
An object of the present invention is provision of an accurately shaped inner sole which will maintain its shape for a considerable period of time and is also simple to secure into an appropriate item of footwear. The shape of the inner sole is, of course, all-important in determining the fit of an item of footwear and its orthopaedic and functional characteristics. Ease of assembly of footwear items is obviously important to footwear manufacturers as regards the cost of production of same.
With this object in view, the present invention provides an inner sole which is pre-formed in a mould by a method of synthetic resin injection and has areas of differing thickness and pliability depending on the foot region to be supported and the type of footwear to which the inner sole is intended to be applied.
The invention will be described further, by way of example, with reference to the accompanying drawing, in which:

Fig. 1 is a perspective view showing the upper surface of a preferred embodiment of the inner sole of the invention;
Fig. 2 is a perspective view showing the underside of the same inner sole; and
Fig. ₃ is a cross-section along the line III-III shown in Fig. 1.

A preferred embodiment of the inner sole of the invention, as illustrated in the drawing, is pre-formed in a mould by a method of synthetic resin injection. This method ensures production of durable inner soles of consistant accurate shape. Moreover the shape of each inner sole is maintained for a long period of time. The shape of the inner sole 1 is particularly important for the fit of the item of footwear, whether boot or shoe, and the orthopaedic and functional characteristics of the boot or shoe also depend on the shape of the inner sole 1.
A suitable material for the inner sole 1 has been found to be thermoplastic nylon No. 6, but, of course, other materials may be equally suitable. The overall shape of the inner sole 1 includes predetermined areas of differing thickness so as to guarantee differing degrees of pliability in different areas according to the foot region to be supported and the type of footwear - for example, walking shoes, sports shoes and orthopaedic shoes- require inner soles of different degrees of pliability.
In the region of the sole, the inner sole 1 is thicker in the central area and at the extreme edge, while a peripheral band of diminished thickness in the form of a groove 2 in the upper surface is provided. This groove 2 is intended to receive stitches (not shown) which will secure the inner sole 1 in an appropriate item of footwear. The material of the stitches will lie in the groove 2 and will not protrude above the level of the upper surface of the inner sole 1 so that no discomfort is likely to be caused to a wearer's foot. Although it is faster and easier to glue inner soles into position in items of footwear rather than to stitch same in position, it is preferable to secure same by stitching as this leads to a much more durable product. Accordingly, provision of a special peripheral band of diminished thickness (such as the groove 2) for reception of stitches facilitates production of good quality, long-lasting items of footwear. Moreover, the thin peripheral band guides the stitching needle and facilitates piercing of the inner sole 1 by the needle.
As mentioned, it is possible, within certain limits, to vary the pliability of differing areas of the inner sole 1 by varying the thickness thereof, taking into account the elasticity of the chosen inner sole material. However, in certain types of footwear, it is not possible to provide the required pliability and durability in this way, particularly in the arch area which has to undergo most stress. To this end, in the illustrated embodiment of inner sole 1 an elongate steel leaf spring 3 of appropriate thickness and springiness is accommodated in a slot 6 in the underside of the inner sole 1. This slot 6 extends between the region of the heel and the arch area of the inner sole 1. The spring 3 is attached in the slot 6 at each end by means of rivets 4,5 extending through the inner sole 1 and the spring 3. This inner sole 1 is substantially rigid and is suitable for certain types of footwear such as skating boots, cycling shoes etc., in which the sole of the boot or shoe itself is relatively stiff. In other words provision of a spring 6 makes the inner sole 1 sturdier and also more resilient.
The invention is not, of course, limited to the details of the above-described embodiment and many variations are possible. For example, the peripheral band of diminished thickness may in some case be formed by a groove on the underside instead of the upper surface of the inner sole. Also the spring may be attached in the slot only at the end disposed in the heel region, the free end in the arch region being capable of sliding slightly within the slot, thereby endowing the inner sole with a particular springiness required in certain shoes and boots. In other embodiments for other types of footwear, of course, the presence of a slot and/or a spring is not essential.

Claims

1. An inner sole which is pre-formed in a mould by a method of synthetic resin injection, characterized in that it has areas of differing thickness and pliability depending on the foot region to be supported and the type of footwear to which the inner sole (1) is intended to be applied.

2. An inner sole as claimed in Claim 1, characterized in that it has, at least in the region of the sole, a peripheral band of diminished thickness which is intended to receive stitches to hold the inner sole (1) in position in an appropriate item of footwear.

3. An inner sole as claimed in Claim 2, characterized in that the peripheral band is in the form of a groove (2) in the upper surface of the inner sole (1) so that the material of the stitches does not protrude above the level of said upper surface, thereby avoiding discomfort to a wearer's foot.

4. An inner sole as claimed in Claim 1,2 or 3 characterized in that an elongate leaf spring (3) is accommodated in a slot (6) provided in the underside of the inner sole (1).

5. An inner sole as claimed in any preceding claim, characterized in that one end of an elongate leaf spring (3) is attached to the underside of the inner sole (1) in the region of the heel so as to allow some sliding of the free end of the spring (3) towards the region of the sole (1).

6. An inner sole as claimed in Claim 4, characterized in that the leaf spring (3) is attached in the slot (6) at both ends and thereby enhances the sturdiness of the inner sole (1).

7. An inner sole according to the preceding claims, and substantially as herein described and illustrated.