GB2234152A

GB2234152A - Method of making a sole for an article of footwear

Info

Publication number: GB2234152A
Application number: GB9015933A
Authority: GB
Inventors: Wilfred Wilson
Original assignee: UK SHOE GROUP Ltd
Current assignee: UK SHOE GROUP Ltd
Priority date: 1989-07-26
Filing date: 1990-07-20
Publication date: 1991-01-30
Anticipated expiration: 2010-07-20
Also published as: GB8917112D0; GB2234152B; GB9015933D0

Abstract

In a method of forming a sole, components 10 and 11 are cut so they fit the peripheral dimensions of the vulcanising mould. The outer component 10 is formed from a hard-wearing rubber, whilst the inner component 11 is made from a much softer rubber. Because of their size relative to the mould, the components form an effective seal with the sides of the mould, when placed therein, such that the material from one component will not leak past the other. This arrangement allows for the vulcanisation of rubber soles where the hardness of the rubber changes through its thickness from hard rubber on the outer surface to soft shock absorbing rubber on the inner surface. <IMAGE>

Description

Method of Makings a Sole for an Article of Footwear This invention relates to making a sole for an article of footwear.

In recent years considerable efforts have been made to achieve soles for footwear which will absorb shock. In many cases this has taken the form of complicated moulds providing air chambers or air passages within the sole, but in other cases attempts have been made to provide a "dual density" sole in which the lower, ground engaging, portion is made of a hard-wearing material and the upper portion is made of a softer material. Some success has been achieved in this direction using plastics where the hard-wearing outer sole can be moulded first and the softer inner sole portion can be injected between the outer sole and the article of footwear. However, for many purposes the properties of these plastics are less satisfactory than rubber or artificial rubber.

Most rubber soles are formed on to footwear by a vulcanising process which demands that the rubber sole pieces which are placed in to the mould are undersized relative to the mould so that all air can be eliminated, otherwise air pockets and defects can appear in the sole.

This invention consists in a method of making a sole for an article of footwear, comprising inserting inner and outer rubber or artificial rubber sole components in to a vulcanising mould, forming a seal between the mould and the peripheral edge of at least one of the components and vulcanising all of the components such that they are welded together.

Preferably the article of footwear is simultaneously introduced in to the mould so that the sole is simultaneously attached to the footwear, for example, by a hot melt adhesive.

In a preferred embodiment a seal is formed between both components and the moulds. This is most simply achieved by sizing the component or components such that their peripheral edge or edges engage the side of the mould. In this way the material from one component is prevented from leaking passed the material of the other component.

Alternatively the seal may be formed by at least the outer component being oversized, in which case the mould is provided with cooperating formations for sealing on the excess margin of that component.

Each component may comprise a sole portion and a heel portion and the inner and outer components may have different physical characteristics. For example, the inner component may have a lower density than the other component and the inner component may be more resilient than the outer component.

Other components may be inserted in the mould to enhance other characteristics of the sole. For example, the protective plate may be inserted between the inner and outer components to limit the penetration of nails and the like.

The inner or outer components may comprise a plurality of layers of the same or different materials.

The invention also includes an article of footwear having a sole manufactured by the method as described above.

Although the invention has been defined above, it is to be understood it includes any inventive combination of the features set out above or in the following description.

The invention may be performed in various ways and specific embodiments will now be described by way of example with reference to the accompanying drawings, in which; Figure 1 is a view from below of the sole components for use in the invention; Figure 2 is a side view of the components of Figure 1; and Figure 3 shows a diagrammatic detail of an edge portion of a vulcanising mould.

The method of forming a sole in accordance with the invention may be performed in standard vulcanising moulds using standard vulcanising procedures, except as indicated below.

In the Applicant's method sole components 10 and 11 are cut so that they fit the peripheral dimensions of the vulcanising mould in which they are to be used. Component 10 is formed from a hard-wearing rubber and is constituted by a heel portion 12 and a sole portion 13. Component 11 is made of a much softer rubber, which would be quite unsuitable for providing a wearing surface, and is constituted by heel portions 14,15 and a sole portion 16.

The heel could be formed by a single section of material, but it is convenient to cut out all parts of component 11 from a single sheet.

When components 10 and 11 are placed in the vulcanising mould they form an effective seal with the sides of the mould such that the material from one component will not leak passed the other. It will be understood that the seal only needs to exist when the heat and pressure are operating in the mould and there may not be a recognisable physical seal when the components are simply placed in the mould.

This method allows, for the first time, the vulcanisation of rubber soles where the hardness of the rubber varies throughout its thickness in a controller manner, from hardening rubber on the bottom surface to soft shock absorbent flexible rubber where the footwear is attached. Its development flies in the face of traditional vulcanising thinking which demands that the components be undersized. This is made possible by the realisation that any trapped air will be retained above the outer component 10 and will therefore not interfere with the wearing characteristics of the sole. Indeed a certain amount of trapped air will enhance the comfort of the footwear.

The method also enables a sole to be 'tailored' to provide particular characteristics. For instance outer components having good non-slip or anti-static properties could be combined with particularly resilient inner components 11; and by way of further example a protective plate 17 could be inserted between the inner and outer components to prevent the penetration of sharp objects.

One immediate advantage of the new method is that it enables vulcanised heels to be manufactured which can pass a 30 joule compression test which is now required by the West German Standards Authorities.

Any appropriate method of forming the seal between the components and the mould is included within the scope of the invention, for example, at least the outer component 10 could be oversized so that its peripheral margin is trapped between formations 18 and 19 of the mould.

Claims

1. A method of making a sole for an article of footwear comprising inserting inner and outer unvulcanised rubber or artificial rubber sole components into a vulcanising mould, forming a seal between the mould and a peripheral edge of at least one component and vulcanising all of the components such that they welded together.

2. A method as claimed in Claim 1, wherein there is a seal between both components and the mould.

3. A method as claimed in Claim 1 or Claim 2, wherein the seal or seals is formed by sizing the component or components such that the peripheral edges or edges engages the side of the mould.

4. A method as claimed in Claim 1 or Claim 2, wherein the seal is formed by at least the outer component is oversized and the mould has cooperating formations for sealing on the excess margin of the component.

5. A method as claimed in any one of Claims 1 to 4, wherein each component comprises a sole portion and a heel portion.

6. A method as claimed in any one of the preceding claims, wherein the inner and outer components have different physical characteristics.

7. A method as claimed in Claim 6, wherein the inner component has a lower density than the outer component.

8. A method as claimed in Claim 6 or Claim 7, wherein the inner component is more resilient than the outer component.

9. A method as claimed in any one of the preceding claims further comprising inserting a protective plate between the inner and outer components.

10. A method as claimed in any one of the preceding claims, wherein the inner or outer component comprises a plurality of layers of the same or different unvulcanised rubber materials.

11. A method of making a sole for an article of footwear substantially as hereinbefore described with reference to the following description.

12. An article of footwear manufactured by the method of any of the preceding claims.