Plastic article or earthenware shaping or treating: apparatus – Distinct means to feed – support or manipulate preform stock... – Female mold type means
Reexamination Certificate
1998-09-17
2001-02-06
Pyon, Harold (Department: 1722)
Plastic article or earthenware shaping or treating: apparatus
Distinct means to feed, support or manipulate preform stock...
Female mold type means
C425S468000, C425SDIG004, C264S271100, C264S313000
Reexamination Certificate
active
06183233
ABSTRACT:
BACKGROUND OF THE INVENTION
The field of the present invention is golf club shafts and, more particularly, reduced weight golf club shafts and methods of manufacturing the same.
Recently, substantial attention has been directed toward the development of lightweight golf club shafts that are manufactured from various composite materials or, more particularly, from a set of plies of “pre-preg” composite sheet. Pre-preg composite sheets are formed by pre-impregnating strands of fiber, for example, carbon or glass, within a binding matrix such as a thermoset epoxy resin or thermoplastic resin. The binding matrix or resin is staged such that it holds the fibers together and forms a malleable sheet.
Numerous shafts are now manufactured by wrapping a set of plies of pre-preg composite sheet around a mandrel in a predetermined manner, wrapping the various plies in a binding material such as cellophane or polypropylene tape, and heating the ply-wrapped mandrel to a predetermined temperature for a time sufficient to allow the resin comprising the plies of pre-preg composite sheet to become fully cured. Once the resin has been fully cured, the binding material may be removed from the exterior of the shaft, and the mandrel may be removed from the core of the shaft. Finally, the shaft may be lightly sanded and painted prior to being inserted into a golf club head.
Through the use of composite materials, it has become possible to manufacture reduced weight shafts for golf clubs, and many shaft manufacturers are now offering for sale ultralight shafts having, for example, a mass less than 70 grams. The extent to which the weight of a shaft may be reduced, however, is limited substantially by the structural requirements that must be met by the tip of the shaft that is affixed within the golf club head. In short, if the walls of the shaft tip are made too thin in an effort to reduce the weight of the shaft, the tip will likely fail or shatter during use. This is particularly true for those golf club head designs that employ a shortened hosel, as such designs provide less structural support for the shaft tip.
It will also be noted that, when a golf club head incorporates a bored-through design whereby the shaft extends through the club head, it is generally necessary to affix a plug in the open end of the shaft tip after the shaft tip has been inserted through the golf club head. This gives the assembled golf club a pleasing cosmetic appearance and, more importantly, prevents debris from entering the shaft tip. However, the use of conventional plugs provides little, if any, structural support to the shaft tip.
Finally, it will be noted that many conventional shaft tips are damaged during trimming processes. Once a shaft is formed, it is common to trim the shaft by removing a segment from both the butt end of the shaft and the tip end. If the walls of the tip are too thin, or if proper care is not taken during the trimming process, serious damage may be caused to the tip during the trimming process.
In view of the many problems that may be encountered in designing and manufacturing reduced weight shafts for golf clubs, it is submitted that those skilled in the art would find improved golf club shafts with reinforced tips and methods of manufacturing such shafts to be quite useful.
SUMMARY OF THE INVENTION
The present invention is directed toward improved methods of manufacturing shafts for golf clubs and to golf club shafts manufactured in accordance with those methods.
In one innovative aspect, the present invention is directed toward a method of manufacturing a shaft for a golf club wherein a plug reinforces and forms an integral portion of a shaft tip. In one such embodiment, a plug is adapted to mate with a distal tip portion of a mandrel. Plies of pre-preg composite sheet may then be wrapped around a portion of the plug and mandrel in a predetermined manner, the plies of pre-preg composite sheet may be wrapped in a binding material such as cellophane or polypropylene tape, and the ply-wrapped mandrel may be heated for a time sufficient to allow the resin in the plies of pre-preg to fully cure. Thereafter, the binding material may be removed from the exterior of the shaft, and the mandrel may be removed from the core of the shaft. The shaft and integral plug may then be trimmed, inserted into a golf club head and affixed within the club head using an epoxy resin. Further, where bored-through head designs are employed, the portion of the plug and shaft tip that extends out from the sole of the club head may be cut off and properly sanded to be flush with the sole. In such instances, a substantial portion of the integral plug preferably will remain within the shaft tip after the protruding portion of the shaft tip has been cut and sanded, thus providing substantial structural support to the shaft tip. The use of an integral plug in accordance with the present invention also facilitates the design and manufacture of reduced weight golf club shafts.
In other innovative aspects, the plug may be formed from a thermally expandable material, and the shaft and integral plug may be manufactured via the cellowrap method described above or via a molding process. In one such embodiment, a bladder may be provided over a mandrel before the plug is fitted onto a male extension provided at a distal tip of the mandrel. Plies of pre-preg composite sheet may then be wrapped around the bladder-covered mandrel and plug in a predetermined manner, and the ply wrapped mandrel and plug may be placed in a mold. If desired, the mandrel may then be withdrawn from the mold leaving the bladder, plug and surrounding plies of pre-preg within the mold. Alternatively, the ply-wrapped mandrel may be left in the mold. In either case, the bladder may be inflated to a predetermined pressure to force the plies of pre-preg against the walls of the mold, and the mold may be heated to a predetermined temperature for a time sufficient to allow the resin comprising the plies of pre-preg to fully cure. Thereafter, the shaft and integral plug may be removed from the mold, the mandrel (if not previously removed) may be removed from the core of the shaft, and the bladder may be removed from the core of the shaft. It will be noted that in such an embodiment, the thermally expansive material comprising the plug will provide not only increased compaction of the plies of pre-preg in the tip region during the curing process, but also substantial structural support in the shaft tip after the curing process has been completed.
In still another innovative aspect, a plug in accordance with the present invention may have one or more hoop ring indentations formed in its exterior surface. In such an embodiment, a shaft may be manufactured in the various manners set forth above. However, during the curing process, resin may be forced into the hoop ring recesses of the plug to more securely affix the plug within the shaft tip.
In still another innovative aspect, the present invention is directed to a mandrel and plug for use in manufacturing a shaft for a golf club. In a preferred form, the mandrel has a distal tip that is notched to form a male extension, and the plug is adapted to detachably receive the male extension. Alternatively, the plug may include a male extension and the distal tip of the mandrel may be adapted to detachably receive the male extension of the plug tip.
Accordingly, it is an object of the present invention to provide improved methods for manufacturing golf club shafts.
It is also an object of the present invention to provide improved golf club shafts and, in particular, reduced weight golf club shafts that are manufactured in accordance with such methods.
It is still another object of the present invention to provide innovative mandrel and plug combinations for use in the manufacture of golf club shafts.
REFERENCES:
patent: 1792852 (1931-02-01), Mattern
patent: 2086275 (1937-07-01), Lemmon
patent: 3705931 (1972-12-01), Confer et al.
patent: 3795559 (1974-03-01), Horn et al.
patent: 4983242 (1991-01-01), Reed
patent: 5083780 (
Galloway J. Andrew
Preece Thomas W.
Reyes Herb
Callaway Golf Company
Catania Michael A.
Lyon & Lyon LLC
Nguyen Thu Khanh T.
Pyon Harold
LandOfFree
Apparatus for manufacturing golf club shafts does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for manufacturing golf club shafts, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for manufacturing golf club shafts will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2586446