This invention relates to studs for footwear and to footwear incorporating those studs.

For convenience of description the term stud is used herein to denote generally any form of local projection that in use can engage the ground, the term therefore including both blunt projections and sharp projections of the kind sometimes referred to as spikes.

Also, for convenience of description, both studs and articles of footwear are described herein as if they are in the orientations they normally assume when they are in use.

Studded footwear is often worn by people playing sports or games. A problem that tends to arise is that studs projecting from the articles of footwear become worn with the result that they become less effective than they were initially. To reduce that problem it is usual for studs, or at least those parts thereof that in use engage the ground, to be made of relatively hard, wear-resistant metal. Nevertheless, it is usual for studs to be such that they can be removed and replaced with fresh ones. While the result is often highly satisfactory, it will be appreciated that to enable studs to be removed and replaced at will it is necessary for the articles of footwear to incorporate sockets or other anchorages for studs and for relatively complex arrangements to be provided to enable studs to be retained by those anchorages sufficiently strongly to withstand the forces applied to the studs when in use but to enable the studs to be removed when worn and to be replaced with fresh studs which are again anchored firmly in place. Arrangements

2 aimed at achieving those ends are necessarily relatively complex.

An aim of the present invention is to provide a form of stud that involves less complexity.

From one aspect the present invention consists in a stud for footwear comprising a body forming an operative portion and an anchorage portion for anchorage of the stud within a lower part of an article of footwear and from which the operative portion projects, the operative portion comprising a ground-engaging portion of hard, wear-resistant material.

A stud in accordance with the invention can be made sufficiently wear-resistant to last for the life of the article of footwear in which it is incorporated.

The hard, wear-resistant material is preferably a sintered or cemented material and may incorporate tungsten carbide and/or cobalt.

The operative portion is preferably formed with a longitudinally extending hole which is closed at its lower end, that is at the end further from the anchorage portion. The wall-thickness of the body or of most of " the body is preferably substantially uniform. The exterior of the operative portion is preferably of tapered shape, becoming narrower with increasing distance from the anchorage portion. The lower end of the operative portion, that is the end further from the anchorage portion, presents the tip of the stud which may be of rounded shape and may blend with the neighbouring part of the remainder or stem of the operative portion. Alternatively the lower end of

the operative portions may be of some other shape; for example it may be flat or it may have sharp edges extending generally lengthwise of the operative portion. It is envisaged that studs embodying the present invention would usually be of a form comprising an anchorage portion with a single operative portion for ground-engagement, but it is within the scope of the present invention to provide a stud of a form comprising an anchorage portion with two or more operative portions for ground-engagement.

The anchorage portion would ordinarily be in the form of a radially enlarged head on the operative portion, and it preferably terminates the body so that no part of the body projects significantly above the anchorage portion. The anchorage portion is preferably of generally circular outline, or so shaped as to fit within a notional circle, with the operative portion projecting axially from it. The anchorage portion may be in the form of a plate or disc, and one or more apertures may extend through that plate. Alternatively it may comprise a plurality of radially extending arms. A lateral extension or lateral extensions may extend from one or more of the radial arms and extend towards a neighbouring arm or arms or link two or more arms together.

From a second aspect the present invention consists in a method of making a stud for footwear that is in accordance with the first aspect of the present invention, the method comprising the steps of forming an intimate mixture of particulate material and a binder, the particulate material comprising one or more substances that can be sintered or cemented together to form a hard, wear-resistant material, moulding the mixture to form a blank in the shape of the desired

body, heating the blank to cause the binder to leave the blank and further heating the blank to a higher temperature to cause the remaining particulate material to be sintered or cemented so that it is converged into the body.

That blank is preferably formed by an injection-moulding process. It is preferred to provide a body of a design which avoids, as far as possible, any relatively thick sections and any significant variations in thickness. In this way, it is found that any tendency to distortion of the body is reduced and that any tendency brittleness is also reduced. Moreover, the cycle-time for the manufacture of the bodies can also be kept relatively short.

There is already known a process for the manufacture of sintered metallic articles comprises the steps of forming an intimate mixture of a binder and particulate metallic material, forming from the mixture by an injection-moulding process a blank in the shape of the desired article, heating the blank to cause the binder to leave the blank and further heating the blank to cause the remaining particulate material to be sintered so that it is converted into the article. That process is usually referred to as metal injection moulding (MIM) . The process used in carrying out a method in accordance with the present invention may use some or all of the techniques used in metal injection moulding. In conventional metal injection moulding the particulate metallic material becomes sintered to form a strong body. In carrying out the present invention the particulate material may comprise a mixture of tungsten carbide (WC) and cobalt (Co) particles which become cemented together as in the product often loosely referred to as 'tungsten carbide'. The

cementation process that occurs in the formation of 'tungsten carbide' may actually be a form of sintering but whether or not that is so, it is to be understood that the present invention is broad enough in scope to include that type of cementation process and analogous cementation processes.

In carrying out a method in accordance with the second aspect of the present invention it is normal for the blank to shrink considerably as it is converted into a body constituting a stud. The shrinkage may, for example, result in a reduction in volume of between 20% and 30%. Bodies made from similarly shaped blanks may themselves differ slightly in their shapes or dimensions but in general it is found that this is unimportant as the preferred methods in which the anchorage portions are anchored within the lower parts of articles of footwear do not require absolute uniformity in the shapes or dimensions of the anchorage portions. Similarly, slight variations in the shapes or dimensions of the projecting parts of the operative portions are normally entirely immaterial and unnoticeable. In this, studs in accordance with the present invention differ from removable and replaceable studs of the kinds previously employed and which generally need to be made to extremely high tolerances if they are to be reliable in use.

From a third aspect the present invention consists in a stud for footwear that is made by a method in accordance with the second aspect of the present inventio .

From a fourth aspect the present invention consists in a method of making a lower part of an article of footwear in which at least one stud in

accordance with the first aspect or the third aspect of the present invention is disposed with its anchorage portion situated within that lower part so that in use it is spaced below a user's foot, while the operative portion projects downwards from said lower part.

Said lower part may comprise a sole or a heel for an article of footwear or a combined sole and heel.

Said lower part may be of laminated form, for example one or more of the component laminae may be of leather, in which case the anchorage portion may be sandwiched between component laminae of the lower part.

Alternatively said lower part may be made as a moulding, such as an injection moulding, in which case the anchorage portion may be so disposed that the moulding is formed around the anchorage portion with the result that the anchorage portion becomes embedded in the moulding.

It is normal for the lower part of an article of footwear to be made of a relatively flexible and resilient material. When the lower part is formed as a moulding which directly embraces the anchorage portion of the body, problems may arise from the unyielding nature of the anchorage portion. In particular, when strong forces are applied to the projecting part of the operative portion there is likely to be a strong tendency for the body to twist relatively to the lower part of the article of footwear and to apply resultant forces to the interior, of the lower portion that may result in the lower part being torn or otherwise damaged; such damage is particularly likely to occur after similar forces have been repeatedly applied to the projecting part.

With a view to reducing those problems and similar problems the stud preferably includes a separately-formed enlargement which is in use situated within said lower part and which is operative ^■ in use, when forces are applied to the stud and give rise to resultant forces applied by the stud to the interior of the lower portion, to distribute those resultant forces more widely in the interior of the lower portion than would be the case if the enlargement were not present.

The enlargement is preferably attached permanently to the body to form with the body a stud of composite construction.

The enlargement is preferably flexible and so formed as to be less hard than the body and more hard than said lower portion; in other words the enlargement is more yielding than the body but less yielding than said lower portion. The enlargement is preferably resilient. In use, when forces are applied to a stud incorporating an enlargement with those properties, the enlargement flexes resiliently and the lower portion in which it is embedded also yields.

The enlargement may be formed from a plastics or similar material and may be formed around the anchorage portion by a moulding operation.

The enlargement and said lower part may be such that the enlargement becomes adhesively attached to or bonded to the lower portion when the lower portion is moulded around the enlargement. For example, the enlargement may be made of high density polyethylene and the lower part may be made of polyurethane.

Alternatively, or in addition, the enlargement may be formed with recesses or holes- in its outer surface which are entered by the material forming said lower part whereby a mechanical engagement or linkage is formed between the enlargement and said lower part.

From a fifth aspect the present invention consists in an article of footwear incorporating a lower part made by a method in accordance with the fourth aspect of the present invention.

Articles of footwear embodying the present invention may be designed and intended for use for any of a wide range of purposes. As indicated above, they may be designed and intended for use in sports and games. Examples of sports and games for which such articles of footwear may be designed and intended are golf, cricket, baseball and track and field sports such as running; that list however is given solely by way of example and is not to be considered as being comprehensive.

There now follows a detailed description to be read with reference to the accompanying drawings of several studs, and their use, which illustrate the invention by way of example.

In the accompanying drawings:-

Figure 1 is a plan view of a stud embodying the present invention,

Figure 2 is a section along the line 2-2 of Figure 1,

Figure 3 is a plan view of another form of stud embodying the present invention,

Figure 4 is a plan view of yet another -form of stud embodying the present invention, and

Figure 5 is a section similar to that of Figure 2 but illustrating yet another form of stud embodying the present invention and neighbouring parts of an outsole in which it is embedded.

The stud illustrated in Figures 1 and 2 is suitable for incorporation in a golf shoe. It comprises a unitary body 1, made in a manner described below, comprising an operative portion 2 for ground-engagement and a radially enlarged head forming an anchorage portion 3 for anchorage within a lower part of an article of footwear. The exterior of the operative portion 2 is of tapered shape, becoming narrower with increasing distance from the anchorage portion 3 , and is formed with a correspondingly tapered hole 4 which is open at its upper end and closed at its lower end. The lower end of the operative portion 2 presents a tip 5 of rounded shape which blends with the neighbouring part of the remainder or stem of the operative portion.

The anchorage portion 3 terminates the body so that no part of the body projects above the anchorage portion. The anchorage portion is of circular outline, with the operative portion projecting axially from it. The anchorage portion is in the shape of a plate or disc formed with four apertures 6 which extend through the disc. Alternatively the anchorage portion may be thought of as comprising four radially extending arms

formed at their outer ends with lateral extensions which link each arm to its neighbouring arms.

The wall thickness of most of the body is substantially uniform, there being a slight local increase in thickness adjacent to the tip 5.

In manufacture of the body 1, there is made an intimate mixture of substances in particulate form and a binder. The substances preferably comprise tungsten carbide and cobalt. The binder is appropriate for those substances and is of the same general kind as the binders currently used in metal injection moulding. The mixture is formed into a blank by an injection moulding technique. The blank is of substantially the same shape as that of the body 1 but is between 20% and 30% larger in volume. The blank is then heated in two stages. In the first stage the blank is heated to a first temperature (which may be about 500°C) such that the binder caused to leave the blank, and in the second stage the blank is heated to a second temperature, higher than the first, (and which may be about 1600°C) so as to cause the metallic substances to become sintered or cemented together, this completing the conversion of the blank into the body. The process used is thus similar to that used in metal injection moulding and will not be described in any more detail here.

in use the body 1 is incorporated in a golf shoe. The golf shoe would normally have about eleven studs, and each stud may comprise a body similar to the body 1. The sole and the heel of the shoe may each be made as an injection moulding of a flexible and resilient plastics material such as polyurethane. Bodies similar to the body 1 are mounted in the moulds

so that when the plastics material is injected into the moulds the anchorage portions become embedded within the sole and heel and are spaced from both the upper and lower surfaces of the mouldings. Plastics material extends through the apertures 6 and assists in anchoring the bodies in place. The operative portions project downwards below the lower surfaces of the mouldings so that in use they can engage the ground. The completed sole and heel are then incorporated into the golf shoe. In an modified construction the sole and heel are moulded as a single, unitary component which is subsequently incorporated into the shoe. In an alternative construction the sole and heel are of laminated form and may for example comprise laminae of leather. In manufacture, holes are formed in a lowermost layer comprising one or more laminae and the operative portions of the bodies are pushed through the holes from above until the anchorage portions engage the upper surface of the lowermost layer. A further layer, which is imperforate and also comprises one or more laminae, is superimposed on the lowermost layer so that the anchorage portions are trapped or sandwiched between the layers. The result and assembly is then incorporated in the golf shoe.

It is intended that the studs should remain in the golf shoe for the full life of the golf shoe as they are strong enough to avoid undue wear in normal use.

The stud illustrated in Figure 3 differs from that shown in Figures 1 and 2 only in that the anchorage portion 7 thereof comprises a plurality of radially projecting arms 8. The arms are of uniform length so that the anchorage portion fits within a notional circle; the axis of the operative portion extends through the centre of that circle and is normal to a

plane containing that circle. The arms 8 are of uniform depth, similar to that of the anchorage portion 3.

Figure 4 illustrates a modification in which the anchorage portion 9 comprises four arms 10 which project radially outwards and are provided at their outer ends with lateral extensions 11 of arcuate shape extending towards neighbouring arms. The anchorage portion is again shaped to fit within a notional circle.

Numerous other modifications and variations are of course possible without departing from the scope of the present invention. For example, the anchorage portions 3 and 9, shown in Figures 1 and 4 respectively, may be modified in such a manner that each has only three radially projecting arms instead of four, those three arms again being uniformly spaced at 120° around the axis of the stud.

Figure 5 shows a stud 12 and a neighbouring part of an outsole 13 which is intended for incorporation in an article of footwear (not shown) . The stud 12 is of composite form, and comprises a unitary body 14, similar to the body 1 shown in Figures 1 and 2 and an enlargement 15 of a plastics or similar material. The body 14 comprises an operative portion 16 and an anchorage portion 17. In manufacture, first the body 14 is formed in the same manner as the body 1 is formed, then the enlargement 15 is injection-moulded around the anchorage portion 17 and the adjacent upper end part of the operative portion 16. Finally the completed stud is placed as an insert in a mould cavity for the outsole 13 and material for the outsole is injected into the cavity so that the enlargement 15 and an adjacent part of the operative portion 16 are

embedded in the outsole. The enlargement 15 and the outsole 13 are preferably made ^" from a flexible and resilient materials but the material from which the enlargement is made is preferably less yielding than that from which the outsole is made. On the other hand the material from which the enlargement is made is preferably considerably more yielding than that from which the body 14 is made. for example, the body may be made from tungsten carbide, the enlargement from high density polyethylene and the outsole from polyurethane. The materials from which the enlargements and the outsole are made are preferably such that they become adhesively attached or bonded to each other; when polyethylene and polyurethane are used, as is preferred, they do become adhesively attached or bonded to each other in that preferred manner.

The enlargement 15 may be formed with recesses or holes in its outer surface so that there is a mechanical engagement or linkage between the enlargement and the outsole 13. For example there may be vertical holes or slots (not shown) extending through the enlargement at locations such that they are not blocked by the anchorage portion 16, the material from which the outsole is formed extending right through those holes so that the enlargement is mechanically linked to the outsole. Alternatively or in addition the enlargement may be formed externally with fins or webs so that recesses are created between them.

In use, when a force is applied to the projecting part of the body 14, a resultant force is applied by the anchorage portion 17 to the enlargement 15 and by the enlargement portion to the neighbouring parts of

the outsole 13. Owing to the shape and extent of the enlargement the maximum resultant pressure applied to the outsole is less than would be the case if the enlargement were not present and the resultant force were exerted on the outsole directly by the body.

It is to be understood that the anchorage portion may be of any desired shape and may, for example, be similar in shape to either those illustrated in Figures 3 and 4 or similar in shape to any of the other anchorage portions mentioned above.