Patent Application
20050245327
The present invention relates to golf club heads and in particular to golf putters and irons.
Golf club putters and irons are traditionally made by an investment casting procedure sometimes referred to as lost-wax casting. According to this method, a wax replica of the club head is made by pouring wax into a mold. The wax replica is then dipped repeatedly into a ceramic slurry to build-up a ceramic mold of sufficient thickness to withstand the metal molding process. The wax is melted out of the mold and then the ceramic is fired to harden it. After it has been fired, the ceramic mold is filled with molten metal. Once the metal has cooled, the mold is broken off to reveal a club head blank that is ready for finish machining, which may include several steps of grinding, polishing, and/or milling.
An alternative method of forming a club head blank is by forging. According to this process, a heated slug of metal is hammered or pressed between a male and female die to form the heated metal into the rough shape of the golf club head. The rough forgine is then subjected to additional machining steps to form the finished club head.
Golf club heads have also traditionally been made by milling the club head out of a solid billet of metal. This, however, is the most expensive way to fabricate a club head because most of the raw material is wasted in the machining process. Typically, the finished club head weighs from 10% to 20% of the original weight of the billet. The remaining 80% to 90% of the billet ends up as chips on the machine room floor.
All of the foregoing methods have their disadvantages. In the lost-wax casting process the build up of the mold takes several days and is labor intensive. Forging is expensive because of the additional tooling and machine operations necessary to forge the blanks and it can only be carried out on materials that respond well to forging. As noted hereinbefore, milling is the most expensive method of manufacturing because of the time necessary to mill a solid billet of metal and because of the substantial wasted material.
The present invention comprises a method of manufacturing a golf club head in which the club head is machined from an extrusion that is already near-net-shape to a vertical profile of the finished club head. According to one embodiment of the invention, an extruded bar having an irregular cross-section that is near-net-shape to the front profile of the club is sliced into a club head blank. Datum are formed in the club head blank by drilling positioning holes, which are used to secure the club head blank to a machining fixture. The club head blanks are then machined into the final configuration including the face, the rear body and hose1 shank while secured to the fixture. In an alternative embodiment of the present invention, the club head blanks are sliced from an extrusion having an irregular cross-section that is near-net-shape to the side profile of the finished club head. A datum surface is created by rough machining a tab that extends forward from what will be the face of the club. The club head blank is secured to a machining fixture by clamping the tab to the fixture. The club head body is then machined into its finished form, after which the face is machined, removing the tab in the process.
Because the club head blanks are formed from an extrusion that is already near-net-shape to the profile of the club, less metal is removed during the machining operations, which results in faster process times, less wasted material and therefore substantial cost savings over the prior art methods of manufacturing golf club heads.
The present invention will be better understood from a reading of the following detailed description, taken in conjunction with the accompanying drawings figures in which like references designate like elements and, in which:
a is a vertical cross section of the club head blank of
b is a representation of the front profile of the golf club of
a is a vertical cross section of the club head blank of
b is a representation of the side profile of the golf club head of
With reference to
With reference to
With reference to
To form club head 42, club head blank 50 is attached to a machining fixture similar to tombstone 40 by clamping tab 56 to the machining fixture. Once club head blank 50 is clamped in place, the lateral surface 58, lower surface 60 and upper surface 62 of body 46 are machined. Thereafter, club head blank 50 is removed from the machining fixture and placed in a second fixture to allow tab 56 to be machined off and face 44 finished. Thereafter, hose1 bore 48 is drilled into body 46 to complete the club head.
With reference to FIG.s 8a and 8b, the side profile of club head 42 projected onto a vertical plane normal to face 44 generates a contour 64 encompassing an area of approximately 1.56 square inches. The cross-sectional area 66 of extruded bar 52 (i.e. the area of blank 50) is approximately 2.1 square inches. Thus, throughout the entire machining operation the cross-sectional area of club head blank 50 is reduced by only approximately 25%. Club heads of different configurations can similarly be produced using side profile near-net-shape extrusions in which the machining operations remove only 15% to 30% of the profile area of the original extrusion. Indeed, the machining operations are so efficient that the finished parts still weigh between 30% and 45% of the weight of the original blank. This compares extremely favorably to billet machining in which the finished part often weighs only 10% to 20% of the weight of original billet. As used herein, near-net-shape means that the extrusion from which the club head blank is severed is no more than 150% larger in cross-section than the corresponding vertical profile (side or front) of the finished part, as opposed to machining of a billet or other wrought material typically provided in regular cross section shapes (e.g. square, round, rectangle). In many cases, however, as demonstrated above, the cross sectional area of the extrusion is only 100% larger or, in the case of the second embodiment, only 17% to 43% larger than the vertical profile area of the finished part (the finished part having a vertical profile area 70% to 85% of the area of the extrusion).
As can be seen from the foregoing use of a near-net-shape extrusion to form the blank from which the golf club head is machined allows for a very highly efficient machining operation with less wasted machining time, less wasted material and therefore substantial cost savings over the prior art methods of manufacturing golf club heads.
Although certain illustrative embodiments and methods have been disclosed herein, it will be apparent from the foregoing disclosure to those skilled in the art that variations and modifications of such embodiments and methods may be made without departing from the spirit and scope of the invention. Accordingly, it is intended that the invention shall be limited only to the extent required by the appended claims and the rules and principals of applicable law.
