GB2139940A - Method of moulding a footwear sole - Google Patents

Abstract

A first sole portion 7 is moulded with recesses in one side thereof extending substantially therethrough, the bottoms of the recesses being covered by thin webs 12. A second sole portion 13 is moulded on the first sole portion 7, forming projections 15 which extend into the recess in sole portion 7 to the webs 12. The webs 12 are removed, e.g. by grinding, to expose the projections 15 of the second sole portion 13. The webs 12 may be formed below the general level of the first sole portion 7 or may be forced outwardly by the projections 15 to facilitate removal of the web to expose the projections 15. The latter provide a design which is visible on the outer surface of the sole portion 7, the two sole portions being of different colours. The first sole portion 7 is moulded in a two port mould (2), 3, Figures 1, 2 (not shown), the mould port 3 with the sole portion 7 thereon defining the mould cavity for second sole portion 13 along with side moulds 4 and a lasted upper 5, 6. <IMAGE>

Description

SPECIFICATION Method of producing a footwear sole This invention relates to a method of producing footwear, and in particular to a method for producing a sole for an article of footwear.

The object of the present invention is to provide a method of producing a two-layer footwear sole, with a portion of one layer projecting through the other layer of the sole. More specifically, the object of the invention is to provide a method of producing a two-colour footwear sole, with one colour showing through the other colour of the sole. In the production of footwear soles with a logo, trademark or other design, the usual practice is to place an insert in the mould cavity in which the sole is produced, so that the insert carrying the design is moulded into the sole, or alternatively to attach a label to the sole using an adhesive following moulding. Both methods are somewhat difficult and labour intensive.

Canadian Patent No. 1,044,410, which issued to Bata Industries Limited on December 1978 discloses a method of moulding a two-layer footwear sole in which projections are moulded integral with a first sole portion in a first moulding operation, the projections extending outwardly through the sole portion moulded in a second moulding operation. Such a method could be used to produce a footwear sole with a logo, trademark or other design of one colour extending through a sole portion of a second colour. However, the method relies upon a somewhat complicated mould structure, which is expensive to produce.

The need exists for a less expensive method of producing atwo-layerfootwear sole with a portion of one layer projecting through the outer layer of the sole. The object of the present invention is to meet such need by providing a relatively simple method of producing such a sole.

Accordingly, the present invention provides a method of producing a footwear sole, comprising the steps of: (a) moulding a first sole portion with a recess in one side thereof extending substantially through said first sole portion to the other side thereof; (b) moulding a second sole portion on said first sole portion to form a projection of said second sole portion extending through substantially the entire thickness of said first sole portion; and (c) removing that part of said first portion covering said projection to expose said projection.

The invention will now be described by way of example with reference to the accompanying drawings, which illustrate a preferred embodiment of the invention and wherein: Figure 1 is a longitudinal sectional view of a mould for moulding a first sole portion; Figure 2 is a cross-section taken generally along the line ll-ll of Figure 1; Figure 3 is a longitudinal sectional view of a mould for moulding a second sole portion, Figure 4 is an enlargement of the portion of the mould of Figure 3 in the circle; and Figure 5 is a cross-section taken generally along line V-V of Figure 3.

With reference to the drawings, the moulding portion of the method of the present invention utilizes a first mould cavity 1 formed by a top mould 2 and a bottom mould 3, which may be a vertically movable mould piston (Figures 1 and 2), and a second mould cavity defined by side moulds 4 and a last 5 with an upper 6 thereon (Figures 3 to 5).

The first moulding step involves the formation of the mould cavity 1 by closing the mould with the top mould 2, the bottom surface of which has a configuration similar two that of a shoe insole. By injecting plastic material into the mould cavity 1, a first sole portion 7 is formed. The bottom surface of the top mould 2 includes projections 8 defining a design, e.g. a logo, word orothertrademarkortradename.

The projections 8 are opposed by shallow recesses 10 in the mould bottom 3. When the mould is closed (Figures 1 and 2) to form the first sole portion 7, the space between the projections 8 and the bottoms of the recesses 10 is quite small. Consequently, thin webs 12 of material close the bottoms of recesses in the first sole portion 7.

Following moulding of the first sole portion 7, the first mould cavity is opened, the first sole portion 7 remaining on the bottom mould 3. The second mould cavity is produced by replacing the top mould 2 with a lasted upper 6. The lasted upper 6, the side moulds 4 and the bottom mould 3 with the first sole portion 7 thereon form the second mould cavity.

Plastic material is injected into the second mould cavity to form second or inner sole portion 13. The inner sole portion 13 covers the first sole portion 7 and connects the latter to the upper 6. The two sole portions 7 and 13 have different colours, and may be formed of different materials. In order to expose the design incorporated in the first, inner sole portion 7, after the sole has been removed from the mould, the webs 12 of material are removed by grinding or milling to expose a limited portion of the second sole portion 13. When moulding the second sole portion 13, projections 15 of material fill the recesses in the first sole portion 7. The bottom surfaces 16 of the projections 15 are aligned with the bottom surface of the first sole portion 7 (Figure 4) so that it is necessary to remove the webs 12 only to expose the projections 15.

When the material used in the method described above is polyurethane, an expansion cavity 17 is provided in the bottom mould 3. The cavity 17 extends around the outer periphery of the sole cavity. During moulding of the first sole portion 7, the polyurethane expands through a narrow passage 18 into the cavity 17. The polyurethane ring 19 filling the cavity 17 and the thin web 20 of polyurethane connecting the ring 19 to the outer sole portion 7 remain on the mould bottom 3 during moulding of the inner sole portion 13 to prevent entry of the polyurethane of the second sole portion 13 into the area between the periphery of the first sole portion 17 and the side of the mould cavity in the bottom mould 3. The ring 19 and the web 20 are removed after the completed sole is removed from the mould.

Claims (5)

1. A method of producing a footwear sole, comprising the steps of: (a) moulding a first sole portion with a recess in one side thereof extending substantially through said first sole portion to the other side thereof; (b) moulding a second sole portion on said first sole portion to form a projection of said second sole portion extending into said recess through substantially the entire thickness of said first sole portion; and (c) removing that part of said first portion covering said projection to expose said projection.

2. A method according to claim 1, wherein said projection extends beyond said other side of said first sole portion to force said part of said first sole portion covering the projection outwardly for facilitating removal thereof and exposure of said first sole portion.

3. A method of producing a footwear sole, substantially as hereinbefore described with reference to the accompanying drawings.

4. A footwear sole produced buy a method as claimed in claim 1,2 or 3.

5. An article of footwear including a sole as claimed in claim 4.