GB2036567A - Golf club - Google Patents

Abstract

Means for the interchangeable fastening of a head assembly (14) on a supporting plate (16) of a golf club shaft (12), comprises a pin or pivot (30) which projects from the head assembly through a hole in the supporting plate and which is laterally profiled for the spring-biassed engagement of two retaining members (40) disposed on the back of the support plate, in which the two retaining members each have two arms and are pivotally mounted on the support plate at opposite sides of the pin or pivot, one pair of arms of the retaining members crossing one another and being provided with gripping formations while the other pair of arms are in resilient operative engagement with one another by means of a linking member. <IMAGE>

Description

SPECIFICATION A fastening for an interchangeable head assembly on a golf club This invention relates to a fastening for an inter changeable head assembly on a supporting plate of a golf club, the fastening comprising a pin or pivot which projects from the head assembly through a hole in the supporting plate and which is laterally profiled for the spring-biassed engagement of retain ing members of a retaining system fixed on the back of the support plate.

A system of this kind is known from US Patent Specification 3,893,670. The advantage of the known system is that a golf player no longer requires a complete set of different individual golf clubs, so that he can have the appropriate club available for different playing conditions. Instead, all he needs is a set of interchangeable head assemblies and a single club consisting of a shaft, a supporting plate fixed at a suitable angle at the bottom end of the shaft, and an arrangement provided at the back of the plate for the interchangeable fastening of the head assemblies on the plate. Such a golf club accordingly gives a considerable saving in weight and space.In the known system, the interchangeable head assembly is substantially secured against any axial displacement with respect to the plate by providing the head assembly with a pin or pivot with a groove formed therein to receive a locking spring which is rigidly secured to the plate. The head assembly is prevented from turning about the pin axis by the provision of another pin on the head assembly, this pin extending through an aperture in the supporting plate, and/or by making the pin and the receiving hole polygonal. Unexpectedly, it has been found with such golf clubs that the head assembly occasionally loses its positional stability after a long period of play and under unfavourable impact conditions.

The object of this invention is to improve the known system so as to increase the positional stability of the head assembly.

Accordingly the present invention provides means forthe interchangeable fastening of a head assembly on a supporting plate of a golf club shaft, comprising a pin or pivot which projects from the head assembly through a hole in the supporting plate and which is laterally profiled forthe spring-biassed engagement of two retaining members disposed on the back of the support plate, in which the two retaining members each have two arms and are pivotally mounted on the support plate at opposite sides of the pin or pivot, one pair of arms of the retaining members crossing one another and being provided with gripping formations while the other pair of arms are in resilient operative engagement with one another by means of a linking member.

This solution, more particularly the construction of the retaining members in the form of two-armed retaining members, the forming of the retaining members with gripping formations on one arm, and the elastic linking of the other ends of the retaining members, has the advantage that the head assembly can be interchanged very easily without requiring a tool for the purpose. Tests have also shown that a golf club provided with the system according to the invention is impaired far less by unfavourable impact conditions than a golf club equipped with the known system. More particularly, the system according to the invention greatly increases positional sta bility of the head assembly on the plate even in comparison with the two-pin construction of the known system for interchangeable fastening of a head assembly on a golf club plate.

Although U.S. Patent Spec. 2,385,565 discloses a retaining system with two retaining arms linked by a spring part, the retaining arms are in that case in positive engagement with a pin and each is separately articulated on another retaining part by its free ends. The known retaining system, however, is not of two-armed construction nor are the retaining members crossed over and formed with gripping means at one end. Accordingly a tool is always required to release the retaining system and replace a head.

According to a preferred embodiment of the invention, the gripping means are arranged so that the retaining means can be released by pressure applied in opposite directions. The advantage of such a system is that the retaining members can be pivoted apart or opened by one hand, the pressure applied to the elastic linking member being distributed uniformly between the two associated arms of the retaining members. In addition, pressure applied in opposite directions can be exerted manually on two parts much more easily than tension applied in opposite directions.

Since the two-armed construction of the retaining members (each arm of the retaining member extending from the pivotal mounting) may act with mechanical advantage, a relatively strong linking member can be used between the two retaining members. A coil spring is suitable for this purpose and is preferably fitted over a pin extending between the retaining member arms remote from the gripping means. Although a strong coil spring is used, it is an easy matter to release the retaining members from the head assembly and hence replace the head assembly, because of the lever action of the retaining members. The retaining members are also strongly pre-stressed towards the pin by the coil spring.

According to a particularly preferred embodiment, the retaining members merge into two coil springs, one of which extends around the pivot of one retaining member on the back of the supporting plate while the other coil spring extends around the pivot of the other retaining member on the back of the supporting plate.

This arrangement not only results in the use of two coil springs, but an arrangement such that they are compressible on actuation in a direction at right angles to the back of the supporting plate. Consequently forces are built up which extend at right angles to those forces which are produced by the springbiassed retaining member engagement between the pin and the retaining members. This increases the positional stability of the head assembly.

According to a preferred arrangement of that embodiment of the invention, the two coil springs are inter-connected by a piece of spring wire. This piece of spring wire increases the elasticity of the system according to the invention and also produces a force component extending at right angles to the above two components. Consequently, three force components orthogonal to one another are built up in all so that positional stability is further increased.

If one of, or preferably both, retaining members is/are inherently elastic, this has the advantage that forces occurring when the golf ball is struck can be taken relatively softly. Consequently, any hard impacts acting on the system and possibly impairing its operation are reduced. According to a preferred embodiment of the invention, the lever system, the two retaining members and the elastic linking member are constructed as an integral double spring adapted to be opened by pressure applied in opposite directions. The construction provides that the impact forces acting on the head assembly are taken particularly well, and it is combined with the advantage of convenient opening of the two retaining members.

To enable known elements to be used on the production side for the releasable connection of two parts, according to another aspect of the invention, the retaining members and the pin are interconnected by a tongue and groove form of engagement, the lateral profiling of the pin being a groove, the base of th groove in the zone of engagement of the retaining member, and/or the pin in the zone of the hole, having polygonal portions. This prevents the head assembly from being turned from its intended position.

According to an exemplary embodiment, selfcentring betwen the tongue and groove provided for engagement (and hence an improvement of the positional stability) is promoted if the groove is of wedge-shaped construction, the distance of the base of the groove and of the engagement edges of the retaining members from the front of the supporting plate and the opening angle of the wedge-shaped groove being so selected that the head assembly is automatically pressed against the supporting plate by the action of the linking member. If the groove is formed in the pin and the retaining members bear directly against the back of the supporting plate, the distance between th base of the groove and the front of the plate must be less than the thickness of the plate.If, however, the grooves are formed in the retaining member, the abovementioned distance of the base of the groove must be greater than the thickness of the plate under otherwise identical conditions.

According to another advantageous embodiment of the invention, the free end of the pin has a wedge-shaped cross-section. This greatly facilitates introduction of the pin into the retaining system because the wedge-shape gives a self-centring while opening of the retaining members on assembly is facilitated by the shape of the pin.

Advantageously, the pin and/or the retaining members have a coating with a low coefficient of friction, at least on their mutually engaged zones. This further facilitates introduction of the pin into the retaining system and in addition the head assembly is drawn even more satisfactorily against the supporting plate by the action of the retaining members.

Exemplary embodiments of the invention will now be described with reference to the diagrammatic drawings wherein: Figure 1 is an end elevation of a first embodiment, Figure 2 is a bottom view of the first embodiment, Figure 3 is a section through the first embodiment viewed in the direction of the arrows Ill-Ill in Figure 2, Figure 4 is a second embodiment viewed from beneath, and Figure 5 is a section through the second embodiment viewed in the direction of the arrows V-V in Figure 4.

With reference to the above-mentioned Figures, there is shown the head end of a golf club 10, in which a supporting plate 16 is integrally connected to the bottom end of the shaft 12 of the golf club 10.

With the shaft 12, the plate 16 makes an angle providing for a maximum impact surface angle for a head assembly 14. The head assembly 14 bears on the front 20 of the plate and is interchangeably connected to the plate 16 by a retaining system provided at the rear thereof. The front edge of the plate 16 merges into a zone 24 in the form of a bead, the cross-section corresponding approximately to the shape of a quadrant of a circle.

Figures 1 to 3 show a first embodiment of the invention, Figure 1 being a reduced-scale endelevation of the embodiment. The head assemblies 14 shown in broken line in Figure 1 are intended to denote their interchangeability. Each head assembly 14 has a conventionally shaped impact surface profile and a planar back 13. The head assembly bears by its back 13 against the likewise plane front 20 of the supporting plate. A symmetrically cylindrical pin 30 propects at right angles from the back 13 of the head assembly and in the operative position it extends through a hole 15 in the plate 16. The diameters of the hole 15 and of the pin 30 are adapted to one another so that the pin 30 fits tightly in the hole 15 but can be conveniently introduced into and removed from said hole.A symmetrically cylindrical annular groove 34 is formed in the pin 30 to receive the retaining members 40, which are the rectilinear portions of a double spring device adapted to open when pressure is applied in opposite directions. Since the pin 30 and the groove 34 are cylindrically symmetrical, a raised edge 18 is formed on the outer edge of the plate 16 for location of the position of the head assembly 14. This edge extends positively around the base zone of the head assembly 14.

The spring device is made in one piece from spring wire and is mounted on the back 22 of the plate by means of two-headed pins 42. The latter are disposed symmetrically with respect to a vertical central plane passing through the pin 30. The entire spring device is also mounted symmetrically with respect to this vertical central plane. Each of its two free ends has an eyelet 62 bent substantially at a right angle. A rubber plug 64 is fitted in each eyelet 62 to provide gripping means on each free end. Two substantially rectilinear lever arms 60 extend from the eyelets and cross one another and merge into the retaining members 40 which are bent therefrom.

Retaining members 40 engage positively in the groove 34 of the pin 30 on each side of the above mentioned vertical central plane. On leaving the groove 34, the retaining members 40 merge into two coils or coil springs 46 which extend around respective pins 42. The ends of the two coil spring 46 are inter-connected by a substantially U-shaped piece of spring wire 44.

The complete spring device is particularly suitable for elastically taking the forces acting on the head assembly 14 when the golf ball is hit, because the spring device is made solely from spring wire and is no mounted on the plate 16 that the forces acting on the pin 30 are usually taken solely by the spring device. Another advantage of making the retaining system in the form of a spring device of this type is that the head assemblies can be interchanged very easily. All that is required to interchange the club head is to press the gripping means of the two free ends of the spring towards one another, and this is readily possible by means of just one hand. The rubber plugs 64 are intended to give maximum uniformity of the pressure distribution to the area of the hand involved.

The groove 34 is formed with a wedge-shape in the pin 30, the distance between the base 36 of the groove and the front 20 of the plate being less than the thickness of the plate 16. Given suitable choice of the wedge angle and the contact of the retaining members 40 against the back 22 of the plate, this ensures that the head assembly 14 is automatically pressed against the plate 16 by the action of the spring.

The edge 18 extending around the head assembly 14 takes any turning moments acting on the head assembly 14. The advantage of the edge 18 is that it is at the maximum distance from the pivot axis extending through the pin 30, under the given design conditions.

The embodiment shown in Figures 4 and 5 has the same lever system operated by pressure in opposite directions, comprising two lever portions 60, the two eyelets 62, and the two rubber plugs 64, as the previous exemplified embodiment. Two retaining members 40' in the form of arms extend from the two lever portions 60 and are mounted by means of two pins 42' at the back 22 of the plate so as to be pivotable symmetrically to a vertically central plane through the pin 30'. Each retaining member 40' terminates in a projection 41 disposed between the pin 42' and the bead 24. An abutment 43 projects from each projection 41. A coil spring 44' is provided between the two abutments 43 and is held in its position by a pin 48 which is pushed therethrough. Pin 48 is rigidly connected to one of the abutments 43 and extends through a bore 50 provided in the other abutment.

The groove 34' is also of wedge-shape construction in this exemplified embodiment, but it is not symmetrically cylindrical or annular, but is formed as a rectilinear incision in the pin 30'. This secures the head assembly 14 against turning.

In this exemplified embodiment, the distance d2 between the base 36' of the groove and the front 20 of the plate, the thickness dl of the plate 16, and the wedge angle of the groove 34' are so selected that the head assembly 14 is automatically pressed against the plate 16 by the action ofthe coil spring 44 on the retaining members 40' bearing against the back 22 of the plate. This automatic biasing of the head assembly 14 against the supporting plate 16 is facilitated by a PTFE coating 38 on the pin 30' and on the retaining members 40'.

The free end 32 of the pin is of frusto-conical con structionto pivot the retaining members 40' apart from one another when the head assembly 14 is pushed into the hole 15. This process is also facilitated by the PTFE coating 38, as a result of its low friction.

Claims (15)

1. Means for the interchangeable fastening of a head assembly on a supporting plate of a golf club shaft, comprising a pin or pivot which projects from the head assembly through a hole in the supporting plate and which is laterally profiled for the springbiassed engagement of two retaining members disposed on the back of the support plate, in which the two retaining members each have two arms and are pivotally mounted on the support plate at opposite sides of the pin or pivot, one pair of arms of the retaining members crossing one another and being provided with gripping formations while the other pair of arms are in resilient operative engagement with one another by means of a linking member.

2. A fastening means according to Claim 1, in which the gripping means are in the form of a lever system adapted to be opened by pressure applied in opposite directions.

3. A fastening means according to Claim 1 or 2, in which the linking member comprises a one coil spring.

4. A fastening means according to Claim 3, in which the coil spring is fitted over a pin extending between those arms of the retaining member which are remote from the gripping formations.

5. A fastening means according to Claim 1 or 2, in which the retaining members are integral with respective coil spring extending around the respective pivots for the retaining members on the back of the plate.

6. A fastening means according to Claim 5, in which the two coil springs are interconnected by a piece of spring wire.

7. A fastening means according to any one of the preceding claims, in which at least one of the retaining members is inherently resilient.

8. A fastening means according to Claim 7, in which both retaining members are inherently resilient.

9. A fastening means according to Claims 2, 5, 6 and 8, in which in the lever system, the two retaining members and the elastic linking member are constructed as an integral spring device adapted to be opened by pressure applied in opposite directions.

10. A fastening means according to any one of the preceding claims, in which the lateral profiling on the pin or pivot comprises a groove, the base of the groove in the zone of engagement of the retaining members and/orthe pin or pivot in the zone of the hole having polygonal configuration.

11. A fastening means according to Claim 10, in which the groove is of wedge-shaped cross-section, the distance of the base of the groove and of the engagement edges of the retaining members from the front of the supporting plate and the opening angle of the wedge-shaped groove being so selected that the head assembly is automatically pressed against the supporting plate by the action of the linking member.

12. Afastening means according to any one of Claims 9 to 11, in which the retaining members engaging in the groove are rectilinear.

13. Afastening means according to any one of the preceding claims, in which the free end of the pin or pivot has a wedge-shaped cross-section.

14. Afastening means according to any one of the preceding claims, in which the pin or pivot and/or the retaining members have a coating having a low coefficient of friction at least in the zone where they engage with one another.

15. A fastening means for interchangeably attaching a golf club head to a shaft substantially as herein described with reference to Figures 1 to 3 or Figures4 and 5 of the accompanying drawings.