WO1991004685A1

WO1991004685A1 - Studded footwear

Info

Publication number: WO1991004685A1
Application number: PCT/GB1990/001515
Authority: WO
Inventors: David Roy Collins
Original assignee: Trisport Limited
Priority date: 1989-10-07
Filing date: 1990-10-04
Publication date: 1991-04-18
Also published as: CN1051495A; CA2067344A1; IE903584A1; KR920702951A; JPH05500910A; KR0146719B1; EP0494937A1; ZA907997B; GB8922644D0; CA2067344C; PT95508A; AU636406B2; AU6531490A

Abstract

It has previously been thought desirable when providing an internally screw-threaded socket (1) for use in studded footwear to provide each socket and a complementary stud (2) with complementary screw-threads with a small helix angle and many turns in order to maximise the frictional grip between the stud (2) and socket (1). The invention provides a multi-start thread requiring at most one and a half turns (560) to achieve full engagement. Contrary to conventional thinking such an arrangement is workable and has advantages over the known single start-threads for studded footwear. Arrangements of sockets and studs with two-start threads and retaining means (14; 16; 17 and 19) to prevent unscrewing of the studs are disclosed.

Description

STUDDED FOOTWEAR

This invention relates to footwear of the kind adapted to have ground-engaging studs releasably attached to it. Footwear of that kind is often worn by people pursuing sports or games. The studs are generally intended to improve the grip of the footwear on the ground, and they may be of a wide variety of shapes. They may, for example be relatively blunt, with flat or rounded ends or more sharp, like spikes. For convenience of description, however, they will hereinafter be referred to generically as studs.

Detachable and replaceable studs are usually provided with spigots which are formed with external screw-threads. Each spigot can be screwed into a socket, in the underside of an article of footwear, formed with an internal screw-thread of complementary form.

Studs and sockets of those kinds are described and illustrated in the specifications of British patents Nos. 1 564 903, 2 028 102, 2 115 683 and 2 191 079.

<_. It is highly desirable that once a stud is fully screwed into a socket it remains securely in place until such time as it is deliberately unscrewed, as for repair or replacement. If a stud does become loose it projects further from the socket than is intended with the result that the likelihood of it inadvertently striking some obstruction is increased, and the likelihood of it adversely affecting the stance of a user is also increased. Moreover, if a stud becomes partially unscrewed so that the distance of the tip of the stud from the socket is increased and a shear force is applied to that tip, something that may well occur when a user is walking or running and catches the stud on a hard, rough surface, the bending moment applied to the socket by the stud is increased thereby increasing the likelihood of damage to the spigot and the socket. In addition, as the length of the spigot inside the socket is reduced, owing to the stud being partially unscrewed, the likelihood of damage is yet further increased.

An article of studded footwear may well have a relatively large number of sockets, each engaged by an associated stud. For example, a man's golf shoe may well have thirteen sockets and studs, so that a pair of such shoes has twenty-six sockets and studs. While the chances of any one socket being damaged during the life of an article of footwear may be relatively small (say 1 in x) , the chances of any one socket in the whole set of sockets (say n in number) in a pair of shoes being damaged is much greater, being the product of those two (i.e. 1 in nx) . It will be appreciated that if a single socket in a pair of shoes or other articles of footwear is damaged or broken it may well be necessary to replace the pair altogether. These considerations, then, highlight the desirability of each stud be.ing securely maintained in place when it has been screwed into its associated socket.

It has therefore been the practice to make the axial lengths of the studs and sockets as great as possible, without causing the sole to be excessively thick, and to provide interengaging threads on the studs and sockets which have a relatively small helix angle and a relatively large number of turns. These design features maximise the area of contact between the spigot and socket and therefore maximise the torque that must be applied to a stud before it starts to become unscrewed.

To reduce yet further the likelihood of a stud becoming unscrewed or partially unscrewed once it has been installed, that is once it has been fully screwed into a socket, various other expedients have been used. For example British patent No. 2 163 037 describes and illustrates a retaining formation which both protects the socket and helps to reduce the likelihood of a stud becoming unscrewed, while British patent application No. 8805473 (Publication No. 2 202 916) describes and illustrates an arrangement of interengaging teeth or a stud and socket for the same purpose.

Nevertheless, the present designs of studs and sockets suffer from other disadvantages, and it is an aim of the present invention to overcome or at least to reduce them.

From a first aspect the present invention consists in a stud for use with an article of studded footwear having an internally screw-threaded socket, the s ud having a spigot provided with an external screw-thread complementary to an internal screw-thread of the socket, the screw-thread of the spigot being a two-start or other multi-start thread, and the stud being adapted to be engaged with the article of footwear by insertion of the spigot into the socket and the rotation of the spigot relative to the socket by no more than one and a half turns (540°) from the start of mutual engagement of the threads.

From a second aspect the present invention consists in an internally screw-threaded socket for incorporation in an article of studded footwear, the socket having an internal screw-thread which is of a two-start or other multi-start thread form and is adapted for use with a stud for the article of footwear having a spigot with an external screw-thread of complementary two-start or other multi-start thread form, the multi-start screw-thread in the socket being such that the stud can be fully engaged with the socket by insertion of the spigot into the socket accompanied by rotation of the spigot relative to the socket through no more than one and a half turns (540°) from the start of mutual engagement of the threads.

When a stud is to be attached to a socket the usual procedure is first for the stud and socket to be brought into mutual axial alignment and then for the stud to be moved axially towards the socket without any relative rotation until the leading threads on the spigot and socket about one other. After that abutment has occurred the stud is rotated relative to the socket so that the threads become increasing engaged with one another, rotation continuing until the stud is installed. The relative rotational positions of the stud and socket, up to the time when the threads abut one another is entirely arbitrary. Consequently, it is almost always the case that after abutment the stud must be rotated through some angle relative to the socket before the threads start to come into mutual engagement, that is they reach a state in which the stud and socket cannot thereafter be parted merely by relative axial movement between them, unaccompanied by relative rotation.

From a third aspect the present invention consists in a stud according to the first aspect of the present invention in combination with a complementary socket in accordance with the second aspect of the present invention.

From a fourth aspect the present invention consists in an article of footwear incorporating at least one socket in accordance with the second aspect of the present invention.

Preferably an article of footwear in accordance with the third aspect of the present invention is characterised in that the socket or each such socket is provided with a complementary stud in accordance with the first aspect of the present invention.

A two-start thread is often preferred but it may sometimes be desirable to use a three-start thread or a thread with yet more starts.

Preferably said rotation of the spigot relative to the socket is no more than one and a quarter turns

(450°) from the start of mutual engagement of the threads, a particularly preferred rotation being substantially a single turn (360°) from the start of mutual engagement of the threads.

When a stud is being attached to an article of footwear, the arrangement is usually such that a torque is applied to the stud to rotate it relative to the socket and that rotation of the stud continues until a strong resistance to further rotation is encountered. This may be caused by the engagement between complementary abutment faces on the stud arid socket or by the engagement between an abutment face on the stud and a complementary abutment face on the article of footwear. During the final stages of engagement of a stud with a socket, the mutually abutting faces of the screw-threads may be brought into tight engagement with each other, and the resultant frictional forces tend to resist or assist in resisting the unscrewing of the spigot. A spanner-like hand tool may be used to apply an increased torque during the final stages of such engagement. When, as is preferred, the screw-threads presenting one or both of the abutment faces are made of a plastics material, there is a tendency for the threads to yield slightly, which enhances the grip between the threads on the spigot and the threads in the socket. It would, nevertheless, be possible to employ metal threads and they may be particularly suitable when threads with three or more starts are used.

The present invention is, at least in part, based on the discovery or realisation that although the use of a two-start or other multi-start thread of a length such as to require rotation of a spigot through a reduced angle to achieve full engagement of the stud with a socket may lead to a small increase in the helix angle and consequently to some reduction in .the frictional forces resisting unscrewing, any such reduction can be made so small as to be acceptable.

Moreover, as indicated above, various expedients have been used to reduce the likelihood of a stud becoming unscrewed or partially unscrewed once it has been fully engaged with a socket. Preferably one or more such expedients are used in conjunction with the present invention. This reduces the reliance placed on the frictional forces acting between the threads maintaining the stud fully engaged with the socket. Retaining means provided to reduce the likelihood of a stud engaged with a socket from becoming unscrewed may comprise teeth for co-operation with complementary teeth provided on the socket; alternatively, or in addition, such retaining means may comprise a retaining ring disposed outwards of the spigot, the retaining ring preventing the outer edge of the socket from expanding outwards.

Several advantages stem from the use of the present invention. The following discussion is based on the use of two-start threads but it will readily be appreciated that it applies in substance to other multi-start threads. First, as indicated above, when a stud is being engaged with a socket it is initially necessary to rotate it to a position in which the eϋds of the threads on the spigot and socket come into mutual engagement with each other. With a single-start thread, such as has been used hitherto, the average angle through which a stud must be rotated to achieve that mutual engagement is half a turn (180°) , whereas with a two-start thread that angle is reduced to a quarter of a turn (90°) . Secondly, problems may arise from the fact that when a spigot is about to be engaged with a socket the axis of the spigot may be somewhat inclined to the axis of the socket which it is to enter. Consequently, when a stud with a single-start thread is about to be engaged with a socket and has been rotated to a position in which the ends of the threads on the spigot and socket are just coming into mutual engagement with each other there is a danger that the spigot may be cross-threaded* and that the socket will be damaged. That danger is much reduced when a two-start thread is used. Thirdly, use of the invention much reduces the labour required to install a complete set of studs in a pair of shoes or other articles of footwear. When twenty-six studs arq/ to be installed, for example, in a pair of golf-shoes and the spigots are of conventional form, each with three and a half turns of single-start thread, the total number of turns required on average is one hundred and four. The reason for this is that on average each stud must be rotated through half a turn to bring the threads on the spigot and stud into mutual engagement and then through a further three and a half turns to bring about full engagement. With the present invention, however, using spigots each with a turn and a quarter of two-start thread the total number of turns would be on average halved. That is, on average each stud would first have to be rotated through a quarter of a turn to bring the threads on the spigot and socket into mutual engagement, and then have to be rotated through a further one and a quarter turns to bring about full engagement. Likewise the number of turns required to unscrew a set of studs would be reduced from ninety-one (i.e. 3.5 x 26) to thirty two and a half (i.e. 1.25 x 26) . Thus the turns required to remove a set of worn studs and replace them with new ones would be reduced from an average of one hundred and ninety five

(i.e. 104 + 91) to an average of eighty eight and a half (i.e. 56 + 32.5) .

Embodiments of the invention will now be described by way of example only, with reference to the accompanying drawings of which:-

Figure 1 shows a stud with a two-start thread embodying the present invention;

Figure 2 shows a feature of detail of the stud of Figure 1; Figure 3 shows a socket with a two-start thread embodying the present invention; and

Figures 4 to 6 are drawings from a previously published British patent illustrating retaining means adapted to reduce the likelihood of a stud becoming unscrewed from a complementary socket.

In the specific embodiment shown in Figures 1 to 3 of the drawings there are provided a stud and socket for a studded sports shoe having sockets and studs generally similar to those described and illustrated in the specification of British patent No. 2 115 683, and differing from them only in that the single-start thread in each socket and on each spigot is now replaced by a two-start thread and in that each stud can be fully engaged with an associated socket by rotation through about one whole turn (360°) from an initial position in which ends of the threads on the spigot and those in the socket are just in mutual engagement.

Figure 3 illustrates a screw-threaded socket 1 made of a plastics material and adapted to , be incorporated in the sole or heel of a studded shoe, and Figures 1 and 2 illustrate a screw-threaded stud 2 adapted to be engaged with the socket 1. The socket 1 has a barrel 3 with an internal screw-thread 4. The screw-thread 4 is a two-start screw-thread. The stud 2 comprises a support 5 made from a plastics material and a metal pin element 6 permanently secured to the support. The pin element 6 has a stem 7 which extends through an axial hole in the support 5.

At one end the stem has a small flange 8 which abuts the support and at the other end the stem is riveted over, as indicated at 9, after assembly with the support, in order to secure the pin element and the support permanently together. The pin element 6 also has a ground-engaging head 10 which projects from the support. The support 5 comprises an externally screw-threaded spigot 11, for engaging the thread 4 in the socket, and a radially extending flange 12, for engaging the underside of the sole or heel beyond the socket. Recesses 13 in the underside of the flange 12 are adapted to receive pegs of complementary shape on a face-spanner which is used to screw the stud into engagement with the socket and to remove it when required.

A retaining ring 14 projects upwards from the upper face of the flange 12. It is spaced outward of spigot 11 so as to prevent radially outward expansion of the socket, as described in the specification of British patent No. 2 163 037.

In a further modification each spigot and its associated socket are provided with interengaging teeth of the kind described in the specification of British patent application No. 2 202 916, the teeth on the stud preferably being mounted on the retaining ring 14. Figure 4 is a drawing from the specification of British patent No. 2 209 916 illustrating a support 15 generally similar to the support 5 and provided with a retaining ring 16 like the ring 14. Teeth 17 project from the ring 16 as shown. Figures 5 and 6, which are taken from the same patent specification, show a socket 18, generally similar to the socket 1; the barrel of the socket has teeth 19 of its outer face which in use co-operate with the teeth 17 on the stud, in the manner described. British Patent No. 2 209 916 describes and illustrates a spigot and socket each with a single-start thread. As indicated above, however, Figures 4, 5 and 6 are included in the present specification merely to illustrate the ring 16 and teeth 17 and 19 which could equally well be applied to a stud and socket in accordance with the present invention.

As described in the aforementioned specification No. 2 202 916 the arrangement is preferably such that when a sufficiently high torque is applied to the stud to unscrew it from the socket at least some of the teeth on the stud are broken off the stud.

In a yet further modification (not illustrated) the teeth on the socket are disposed in two spirals or part-helices parallel with the threads inside the socket, and the teeth on the stud are such that their projecting tips lie on two similar spirals or part-helices, the arrangement being such that as a spigot is being engaged into an associated, socket the teeth on the stud do not touch the teeth on the socket until the stud is almost fully engaged with the socket and must be finally rotated through only a relatively small fraction of a turn before becoming fully engaged with the socket. Then, during that final fractional rotation of the stud, all the teeth on the socket are engaged simultaneously, or substantially simultaneously, by teeth on the stud and finally the teeth on the stud snap past the teeth on the socket so that when the stud is fully engaged with the socket each tooth on the socket has a complementary tooth on the stud abutting it or closely adjacent to it so as strongly to resist any torque tending to unscrew the spigot again. In the preferred arrangements described and illustrated in the aforementioned specification No. 2 202 916, the number of teeth on the stud exceeds the number of teeth on the socket; this is to ensure that when the stud has been fully installed at least some of the teeth on the stud are not being distorted by being in permanent engagement with teeth on the socket. With the arrangement described above, however, in which the teeth on the studs and sockets are both arranged in two spirals or part-helices, this is no longer necessary, and it is preferred to provide the same number of teeth on the stud as are on the socket. If is often convenient to provide six teeth on the socket and six teeth on the stud, the teeth in each case being uniformly disposed around the axis of the socket or stud. The two teeth of each pair of diametrically opposed teeth are of similar shape and disposition. Thus, for example, if one considers in turn the axial lengths of the teeth on the stud, the first tooth is relatively short, the second is of medium length and the third tooth is relatively long, the fourth tooth is like the first, the fifth like the second and the sixth like the third. If desired there may be a different number of teeth, such as eight teeth, but it will be appreciated that in each instance the arrangement should be such that each tooth on the stud has a similar tooth diametrically opposite to it and likewise each tooth on the socket has a similar tooth diametrically opposite to it. In this way it does not matter which of the two threads on the spigot engages either of the two threads in the-socket.

It will be appreciated that when employing the preferred form of studs and sockets described above, in which the teeth are disposed in spirals or part-helices, the torque required to bring about the full engagement of any one stud with its associated socket is negligible during most of the necessary rotation but suddenly increases to a much higher value or values during rotation through the final fraction of a turn during which the teeth on the stud are passing those on the socket. This fact lends itself to the mechanisation of the installation of an initial set of studs in a new article of footwear. Each stud is rotated mechanically until a significant resistance is encountered and is then rotated through a predetermined fraction of a rotation by the application of a much-increased torque.

It is to be understood that use of this preferred form of the present invention requires each stud to be screwed fully into its final position. Hitherto it has sometimes been the case that sockets have been installed in soles that are thicker than the intended thickness and that the engagement between a flange on a stud and the underside of the sole has prevented the stud being screwed fully into the socket. The preferred form of the present invention is therefore unsuitable for use in circumstances such as those.

As use of the present invention requires the design of the studs and sockets to be such that a stud can be fully installed by rotation through no more than one and a half complete turns from the start of mutual engagement of the threads, and preferably through about a single turn from the start of mutual engagement of the threads, and as it is desirable for the helix angle to be relatively small so that the frictional forces resisting unscrewing remain relatively high, the total axial length of the spigot and socket can be made relatively small. Indeed, it may well be possible to provide sockets of an axial length less than those provided hitherto; this enables the soles of the articles of footwear in which they are mounted to be of correspondingly reduced thickness.

Finally it will be understood that although the foregoing examples relate to studs and sockets with two-start threads they can readily be adapted for use with three-start threads or threads with yet more starts.

Claims

1. A stud for use with an article of studded footwear having an internally screw-threaded socket (1) , the stud (2) having a spigot (11) provided with an external screw-thread complementary to an internal screw-thread (4) of the socket (1) , the screw-thread of the spigot (11) being a two-start or other multi-start thread, and the stud (2) being adapted to be engaged with the article of footwear by insertion of the spigot (11) into the socket (2) and the rotation of the spigot relative to the socket by no more than one and a half turns (540°) from the start of mutual engagement of the threads.

2. A stud according to claim 1, characterised in that the multi-start thread (4) of the stud (2) is a two-start thread.

3. A stud according to claim 1 or claim 2, characterised in that its screw-thread is adapted to achieve full engagement of the stud (2). with the socket (1) by relative rotation of no more than one and a quarter turns (450°) from the start of mutual engagement of the threads.

4. A stud according to claim 3, characterised in that its screw-thread is adapted to achieve full engagement of the stud (2) with the socket (1) by relative rotation of substantially a single turn (360°) from the start of mutual engagement of the threads.

5. A stud according to any preceding claim, characterised in that its spigot (11) is made of plastics material.

6. A stud according to any preceding claim, characterised in that retaining means (14; 16; and/or 17; 19) is provided to reduce the likelihood of a stud engaged with the socket from becoming unscrewed.

7. A stud according to claim 6, characterised in that the retaining means comprises teeth (17) for co-operation with complementary teeth (19) provided on the socket.

8. A stud according to either one of claims 6 and 7, characterised in that the retaining means comprises a retaining ring (14; 16) disposed outwards of the spigot (11) , the retaining ring preventing the outer edge of the socket from expanding outwards.

9. An internally screw-threaded socket (1) for incorporation in an article of studded footwear, the socket having an internal screw-thread (4) which is of a two-start or other multi-start thread form and is adapted for use with a stud (2) for the article of footwear having a spigot (11) with an external screw-thread of complementary two-start or other multi-start thread form, the multi-start screw-thread in the socket (1) being such that the stud (2) can be fully engaged with the socket by insertion of the spigot (11) into the socket (1) accompanied by rotation of the spigot relative to the socket through no more than one and a half turns (540°) from the start of mutual engagement of the threads.

10. A socket according to claim 9, characterised in that the multi-start thread (4) of the socket is a two-start thread.

11. A socket according to either one of claims 9 and 10, characterised in that its screw-thread (4) is such that the stud (2) can be fully engaged with the socket (1) by relative rotation of no more than one and a quarter turns (450°) from the start of mutual engagement of the threads.

12. A socket according to claim 11, characterised in that its screw-thread (4) is such that the stud (2) can be fully engaged with the socket (1) by relative rotation of substantially a single turn from the start of mutual engagement of the threads.

13. A socket according to any one of claims 9 to 12, characterised in that at least its screw-thread (4) is made of plastics material.

14. A socket according to any one of claims 9 to 13, characterised in that retaining means (19) is provided to reduce the likelihood of a complementary stud (2) engaged with the socket from becoming inadvertently unscrewed.

15. In combination a stud according to any of claim? 1 to 8 in combination with a complementary socket according to any one of claims 9 to 14.

16. An article of footwear incorporating at least one socket (1) in accordance with any one of claims 9 to 14.

17. An article of footwear according- to claim 16, characterised in that the socket (1) or each such socket (1) is provided with a complementary stud (2) in accordance with any one of claims 1 to 8.