Golf club with interchangeable head-shaft connections

A golf club (20) having a club head (22) with an interchangeable shaft (40) is disclosed herein. The golf club (20) includes a tube (44, 144) mounted in the club head (22), and a sleeve (46, 146) mounted on a tip end (50) of the shaft (40). The tube (44, 144) includes a tapered portion (60, 160) and a rotation prevention portion (62, 162). The sleeve (46, 146) has a frustoconical portion (72, 172) and a keyed portion (74, 174) that are respectively received in the tapered portion (60, 160) and the rotation prevention portion (62, 162) of the tube (44, 144). The golf club (20) further includes a mechanical fastener (48, 148) for removably securing the shaft (40) to the club head (22).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a golf club having an improved connection for interchanging a shaft with a golf club head.

2. Description of the Related Art

In order to improve their game, golfers often customize their equipment to fit their particular swing. Golf equipment manufacturers have responded by increasing the variety of clubs available to golfers. For example, a particular model of a driver-type golf club may be offered in several different loft angles and lie angles to suit a particular golfer's needs. In addition, golfers can choose shafts, whether metal or graphite, and adjust the length of the shaft to suit their swing. Golf clubs that allow shaft and club head components to be easily interchanged facilitate this customization process.

One example is Wheeler, U.S. Pat. No. 3,524,646 for a Golf Club Assembly. The Wheeler patent discloses a putter having a grip and a putter head, both of which are detachable from a shaft. Fastening members, provided on the upper and lower ends of the shaft, have internal threads, which engage the external threads provided on both the lower end of the grip and the upper end of the putter head shank to secure these components to the shaft. The lower portion of the shaft further includes a flange, which contacts the upper end of the putter head shank, when the putter head is coupled to the shaft.

Another example is Walker, U.S. Pat. No. 5,433,442 for Golf Clubs with Quick Release Heads. The Walker patent discloses a golf club in which the club head is secured to the shaft by a coupling rod and a quick release pin. The upper end of the coupling rod has external threads that and engage the internal threads formed in the lower portion of the shaft. The lower end of the coupling rod, which is inserted into the hosel of the club head, has diametric apertures that align with diametric apertures in the hosel to receive the quick release pin.

Still another example is Roark, U.S. Pat. No. 6,547,673 for an Interchangeable Golf Club Head and Adjustable Handle System. The Roark patent discloses a golf club with a quick release for detaching a club head from a shaft. The quick release is a two-piece connector including a lower connector, which is secured in the hosel of the club head, and an upper connector, which is secured in the lower portion of the shaft. The upper connector has a pin and a ball catch that protrude radially outward from the lower end of the upper connector. The upper end of the lower connector has a slot formed therein for receiving the upper connector pin, and a separate hole for receiving the ball catch. When the shaft is coupled to the club head, the lower connector hole retains the ball catch to secure the shaft to the club head.

Two further examples are published applications to Burrows, U.S. Pub. Nos. 2004/0018886 and 2004/0018887, both of which are for a Temporary Golf Club Shaft-Component Connection. The Burrows applications disclose a temporary connection that includes an adapter insert, a socket member, and a mechanical fastener. The adapter insert, which is mounted on a shaft, includes a thrust flange. The socket member, which is mounted on the other golf club component (e.g., a club head), includes a thrust seat for seated reception of the thrust flange. The mechanical fastener (e.g., a compression nut or a lock bolt) removably interconnects the adapter insert and the socket member.

The prior art temporary head-shaft connections have several disadvantages. First, they require that the golf club head have a conventional hosel for attachment. Second, these connections add excessive weight to the club head, thereby minimizing the amount of discretionary mass that may be distributed in the club head to optimize mass properties. Third, the prior art connections offer small, faying surfaces for centering and reacting to bending moments.

BRIEF SUMMARY OF THE INVENTION

The present invention provides an improved club head-shaft connection for cost-effective customization of golf clubs, while providing golfers with golf clubs that provide optimal performance. The connection, which does not require the club head to have a conventional hosel, enables quick and reliable assembly and disassembly of a shaft from the club head. In addition, the head-shaft connection of the present golf club provides a larger faying surface between the components without adding excessive weight. The reduced weight of the present connection enables more discretionary mass to be distributed to favorable locations in the club head to enhance its performance.

One aspect of the present invention is a golf club including a club head, a tube, a shaft, a sleeve and a mechanical fastener. The tube, which is mounted in the club head, has a tapered portion, a rotation prevention portion, and an upper end inner diameter that is larger than the inner diameter at the lower end. The rotation prevention portion of the tube defines a keyway that has a non-circular configuration. The sleeve is mounted on a tip end of the shaft, which is then inserted into the tube. A lower section of the sleeve includes a frustoconical portion and a keyed portion. When the shaft is connected to the club head, the frustoconical portion and keyed portion of the sleeve are respectively received in the tapered portion and keyway portion of the tube. The frustoconical portion of the sleeve extends at least a quarter of the length of the lower section of the tube to provide an increased surface area for contact with the tapered portion of the tube.

DETAILED DESCRIPTION OF THE INVENTION

As shown inFIGS. 1 and 2, a golf club is generally designated20. The golf club20has a club head22and a shaft40that is coupled to the club head22. The club head22is a wood-type golf club head with a body23having a crown,24, a sole26, a ribbon28and a striking plate30. The striking plate30generally extends along the front of the club head22from a heel end32to a toe end34. The club head body23preferably has a hollow interior with an internal hosel31(FIG. 3) for receiving the tip end of the shaft40.

The body23is preferably composed of a metallic material, such as titanium, titanium alloy, stainless steel, or the like. Alternatively, the body23may be composed of multiple materials, such as a titanium face cup attached to a carbon composite body. The body23has a large volume, preferably greater than 300 cubic centimeters, and weighs no more than 215 grams, more preferably between 180 and 215 grams. Although the club head22illustrated is a wood-type club head, the club head22may also be an iron-type or putter-type club head.

The shaft40is preferably composed of a graphite material, however, it may be composed of a metallic material, such as stainless steel or titanium. Alternatively, the shaft40may be composed of a hybrid of graphite and metal. The shaft40preferably weighs between 40 grams and 80 grams, more preferably between 50 grams and 75 grams, and is most preferably 65 grams.

The shaft40is coupled to the club head22using a connection42that provides for easy assembly, disassembly and reassembly, thereby facilitating customization of the golf club20. In a preferred embodiment of the invention illustrated inFIGS. 2 and 3, the connection42includes a tube44, a sleeve46and a mechanical fastener48. The sleeve46is mounted on a tip end50of the shaft40. The shaft40with the sleeve46mounted thereon is then inserted in the tube44, which is mounted in the club head22. The mechanical fastener48secures the sleeve46to the tube44to retain the shaft40in connection with the club head22.

The tube44is preferably composed of a metallic material, such as aluminum or titanium, but may also be composed of a suitable non-metallic material. The tube44is preferably treated with an anodizing or tiodizing process to improve the surface hardness and wear resistant properties of the tube44. The tube44may be secured in the internal hosel31of the club head22using an adhesive, such as epoxy. Alternatively, the tube44may be integrally cast or formed with the body23of the club head22. The tube44has an upper end52that is substantially flush with the exterior surface of the crown24of the club head22and a lower end54that extends toward, but not all the way down to, the sole26of the club head22. An opening56extends through the tube44from the upper end52to the lower end54and aligns with an opening58in the sole26.

As best illustrated inFIG. 4, the tube44includes a tapered portion60and a rotation prevention portion62. The tapered portion60is located proximate the upper end52of the tube44and provides a contact surface for receiving the sleeve46, as will be described in greater detail below. The upper end52of the tube44, therefore, has an inner diameter D1that is larger than an inner diameter D2of the lower end54. The rotation prevention portion62, which is preferably located below the tapered portion60, defines a keyway for receiving a portion of the sleeve46. The keyway has a non-circular cross-section to prevent rotation of the sleeve46relative to the tube44. The keyway may have a plurality of splines64, as illustrated inFIGS. 3 and 4, or a rectangular or hexagonal cross-section.

The tube44further includes a flange66that projects radially inward from the sidewall of the tube44. In the preferred embodiment, the flange66is located below the rotation prevention portion62. The flange66provides a surface against which a portion of the mechanical fastener48rests. The flange66extends into the opening56a sufficient distance to prevent the entire mechanical fastener48from passing through, while allowing a portion of the mechanical fastener48to extend into the rotation prevention portion62.

The sleeve46, which is best illustrated inFIG. 5, has an opening68formed in an upper end69thereof for receiving the tip end50of the shaft40. The sleeve46is fixedly secured to the shaft40using an adhesive, such as epoxy. The sleeve46has a lower section70that includes a frustoconical portion72and a keyed portion74. The lower section70has a length L1that is preferably between 0.60 inch and 1.0 inch, more preferably between 0.75 inch and 0.90 inch. The frustoconical portion72of the sleeve46is received in the tapered portion60of the tube44when the shaft40is coupled to the club head22. The frustoconical portion72preferably has a length L2that is a least one quarter of the length L1of the lower section76, more preferably at least one third of the length L1. In one embodiment of the invention, the length L1of the lower section70is approximately 0.8 inch, and the length L2of the frustoconical portion72is approximately 0.3 inch. The longer length L2of the frustoconical portion72provides a greater the contact area with the tapered portion60of the tube44. This region is the compressive load path between the shaft40and the club head22. Because of the larger contact area between the frustoconical portion72and the tapered portion60, there are less localized stresses, and the connection42is better able to react to bending moments than prior art connections. In addition, one or both of the surfaces of the tapered portion60and the frustoconical portion72may be coated with an elastomeric material or other soft, thin material to enhance an even load distribution.

The keyed portion74of the sleeve46has a configuration that is complementary to the keyway of the rotation prevention portion62of the tube44. Thus, inFIG. 5, the keyed portion74has a splined configuration. Alternatively, the keyed portion74may have a rectangular or hexagonal configuration, similar to that of the corresponding keyway.

The sleeve46has a second opening76formed in a lower end77thereof. The opening76is formed with internal threads78for engagement with external threads on the mechanical fastener48. The sleeve46is preferably composed of a metallic material, such as aluminum or titanium. The sleeve46is preferably treated with an anodizing or tiodizing process to improve the surface hardness and wear resistant properties of the sleeve46. A steel liner with internal threads (not shown) may be provided in the opening76for improved wear. Such a steel liner may include a HELI-COIL screw thread insert from Emhart Teknologies or a KEENSERTS insert from Alcoa Fastening Systems.

Assembly of the golf club20includes permanently securing the tube44to the club head22, and the sleeve46to the tip end50of the shaft40. The tip end50of the shaft40with the sleeve46mounted thereon is then inserted into the opening56of the tube44, such that the keyed portion74of the sleeve46engages the keyway of the tube's rotation prevention portion62, and the frustoconical portion72is in contact with the tapered portion60. The mechanical fastener48is then connected to the sleeve46. The mechanical fastener48is preferably composed of steel, titanium or aluminum. As shown inFIGS. 2 and 3, the mechanical fastener48is a screw, such as a socket screw80having a socket head82and external threads84. The socket screw80is inserted into the lower end54of the tube44through the opening58in the sole26of the club head22. The external threads84of the socket screw80engage the internal threads78in the opening76at the lower end77of the sleeve46, while the socket head82abuts the flange66of the tube44. An anti-vibration lock-washer (not shown) may be provided between the socket head82and the flange66to prevent loosening or rattling of the socket screw80.

Because the tube44and the sleeve46are composed of lightweight materials, the connection42does not add unnecessary weight to the golf club20. Further, voids between the various components exist to further reduce weight from this region of the club head22. A first void90is located between the lower end77of the sleeve46and the flange66of the tube44. A second void92is located between the mechanical fastener48and the lower end54of the tube44. The voids90and92decrease the weight of connection42, thereby providing more discretionary mass that may be distributed to favorable positions along club head22.

The golf club20may further include a sealing gasket93, such as an O-ring, to prevent the ingress of water, dirt or other contaminants into the connection42. This is important, since the club head22may be submerged in water for purposes of cleaning. Without the sealing gasket93, water could enter into the threaded joint and result in corrosion or freezing of the threads.

The head-shaft connection42allows the shaft40to be detached from the club head22and replaced with a different shaft. To disassemble the golf club20, the socket screw80is unscrewed from the sleeve46and removed through the opening58in the sole26of the club head22. The shaft40and sleeve46may then be lifted out of the upper end52of the tube44and separated from the club head22. A second shaft and sleeve assembly may then be coupled to the club head22.

When a suitable club head and shaft combination is achieved, the connection42may be made more permanent by applying a bead94of adhesive about the head82of the socket screw80. This adhesive bead94would prevent the average golfer from disassembling the golf club20and interchanging components, thereby enabling the golf club20to conform to the USGA and R&A rules of golf. A skilled golf repair technician, however, would still be able to disassemble the golf club by applying heat locally to the joint. One of ordinary skill in the art will appreciate that alternatives to the adhesive bead94may also be employed. One example is an adhesive washer that is applied between the screw head82and the flange66. Another example is a sleeve of adhesive that is applied about the surface of the screw head82, thereby bonding the socket screw80to the interior surface of the tube44. Still another example is a plug that is inserted into the opening56after the socket screw80. The plug, which engages the screw's socket, is the bonded to interior surface of the tube44using an adhesive.

FIGS. 6–9illustrate a golf club with an alternative connection142for joining a shaft40to a club head22. The connection142includes a tube144, a sleeve146and a mechanical fastener148. The mechanical fastener148is a compression nut96having external threads98. The compression nut96and the sleeve146are placed on the shaft40, with the sleeve146mounted on the tip end50and secured thereto with an adhesive, such as epoxy. The shaft40with the sleeve146and compression nut96thereon is then inserted into the tube144, which is mounted in the club head22. The compression nut96is then tightened to engage the tube144, thereby securing the sleeve146inbetween and connecting the shaft40to the club head22.

The tube144is preferably composed of a metallic material, such as aluminum or titanium, but may also be composed of a suitable non-metallic material. The tube144is secured in the internal hosel31of the club head22using an adhesive, such as epoxy. The tube144has an upper end152that extends above the crown surface24of the club head22. Alternatively, the upper end152of the tube144may be flush with the crown surface24. An opening156extends along a majority of the length of the tube144from the upper end152toward a lower end154. The lower end154of the tube144, however, is closed. The inner diameter D1of the upper end152of the tube144is greater than the inner diameter D2at the lower end154.

The tube144, as illustrated inFIG. 8, includes a connection portion159, a tapered portion160and a rotation prevention portion162. The connection portion159is located proximate the upper end152of the tube144and has internal threads161for engaging the external threads98of the compression nut96. Because the threads161of tube144are internal, the threads161are protected from damage that may occur during storage, manufacture, or customization of the golf club20.

The tapered portion160, which provides a contact surface for receiving the sleeve146, is located below the connection portion159. The rotation prevention portion162is located proximate the lower end154of the tube144and defines a keyway for receiving a portion of the sleeve146. As with the previous embodiment, the keyway has a non-circular cross-section to prevent rotation of the sleeve146relative to the tube144. The keyway of the rotation prevention portion162illustrated inFIGS. 7 and 8is provided with splines164.

The sleeve146is illustrated inFIG. 9. The sleeve has an opening168formed in an upper end169thereof for receiving the tip end50of the shaft40. The sleeve is fixedly secured to the shaft40using an adhesive, such as epoxy. The sleeve146has a lower section170that includes a frustoconical portion172and a keyed portion174. The frustoconical portion172has a length L2that is at least one quarter of the length L1of the lower section170, more preferably at least one third of the length L1, and may be more than half the length L1. The longer length L2of the frustoconical portion172provides a greater contact area with the tapered portion160of the tube144. The keyed portion174of the sleeve146is configured to complement the keyway of the tube's rotation prevention portion162. Thus, the illustrated keyed portion174has a splined configuration.

The golf club illustrated inFIGS. 6 and 7is assembled by permanently securing the tube144to the club head22. Next, the compression nut96is placed over the tip end50of the shaft40. The sleeve146is then permanently secured to the tip end50of the shaft40. The tip end50of the shaft40, carrying the sleeve146and the compression nut96, is then inserted into the opening156in the tube144, such that the keyed portion174of the sleeve146engages the keyway of the tube's rotation prevention portion162, and the frustoconical portion172is in contact with the tapered portion160. The external threads98of the compression nut96are then engaged with the internal threads161of the connection portion159of the tube144to secure the shaft40to the club head22.

As with the previous embodiment, the tube144and the sleeve146are composed of lightweight materials that do not add unnecessary weight to the golf club. In addition, voids are provided in the connection142to further reduce weight from this region of the club head22. A first void186is located between the tip end50of the shaft40and a bottom surface168of the opening188in the sleeve146. A second void190is located between the lower end177of the sleeve146and a bottom surface163of the opening156in the tube144. A third void192is located between the lower end154of the tube144and the sole26of the club head22.

The golf club may further include a sealing gasket93located between the compression nut96and the upper end152of the tube144to prevent water and other contaminants from entering the connection142. A second gasket193may also be provided between the top of the compression nut96and the upper end169of the sleeve146for aesthetic purposes.

When a suitable head and shaft combination is achieved, the connection142may be made more permanent, by applying a cover163over the exposed portion of the compression nut96. The cover163is preferably a thin sheath of rubber or elastomeric material that encloses the indents on the compression nut96, making the compression nut96inaccessible to the average golfer. The cover163may be integral with the sealing gaskets93and193or separate. The connection142may also be made more permanent by extending the lower edge of the head of the compression nut96over the sealing gasket93to overlap the outer wall of the upper end152of the tube144, and applying a bead of adhesive at the overlap. Local application of heat to this joint by a skilled golf repair technician would enable the compression nut96to be separated from the tube144and a different shaft to be combined with the club head.