Games using tangible projectile – Golf – Club or club support
Reexamination Certificate
1999-11-22
2001-10-16
Chapman, Jeanette (Department: 3711)
Games using tangible projectile
Golf
Club or club support
C473S319000
Reexamination Certificate
active
06302805
ABSTRACT:
FIELD OF THE INVENTION
The present invention is directed to club shafts for golf clubs. More specifically, the present invention is directed to a golf club shaft having improved strength, stiffness, durability and torque characteristics.
BACKGROUND
The game of golf is becoming increasingly popular in the United States and internationally. Presently, golfers, both professional and non-professional, are continuously striving to improve their golf game. It is well known that the physical characteristics of the club shaft of a golf club can effect the travel of the golf ball. Club shafts having a high stiffness to weight ratio, low shaft vibration, good strength, good resistance to torsion and good resilience to fatigue are usually preferred by golfers.
Typically, each golf club shaft includes a shaft tip section, a shaft intermediate section and a shaft butt section. The shaft tip section typically has a relatively small outer diameter when compared to the shaft butt section. A head is secured to the shaft tip section, while a grip is secured to the shaft butt section. The shaft intermediate section extends between and tapers from the shaft butt section to the shaft tip section. Usually, the taper is substantially linear or includes a series of sequentially smaller, annular steps.
Unfortunately, existing club shafts are not entirely satisfactory. For example, existing club shafts can be too weak, have poor resistance to torsion and poor resilience to fatigue. One way to improve the strength and resistance to torsion of the club shaft is to increase the wall thickness of the club shaft. However, the resulting thicker walled club shaft is often too heavy and/or has other undesirable performance characteristics.
In light of the above, it is an object of the present invention to provide a club shaft and method for manufacturing a club shaft having improved strength and resistance to fatigue crack propagation. Yet another object of the present invention is to provide a composite club shaft having improved durability, torque characteristics and performance characteristics.
SUMMARY
The present invention is directed to a club shaft for a golf club which satisfies these needs. The club shaft includes a shaft butt section, a shaft tip section, and a shaft intermediate section which connects the shaft butt section to the shaft tip section. The shaft intermediate section has an outer diameter which tapers from the shaft butt section to the shaft tip section.
Uniquely, the rate or amount of taper in the outer diameter of the shaft intermediate section varies along the shaft intermediate section. Stated another way, the slope of the taper varies along the shaft intermediate section. Preferably, the outer diameter of the shaft intermediate section has a slope of approximately zero degrees relative to a shaft longitudinal axis near the shaft butt section and the shaft tip section. This allows the club shaft to have a continuous, smooth geometry and eliminates the abrupt transitions between shaft butt section, the shaft intermediate section, and the shaft tip section. The resulting club shaft has improved strength, durability and torque characteristics, without increasing the wall thickness or fiber modulus of the club shaft.
Each club shaft provided herein can be made by wrapping one or more patterns around a form, i.e. a mandrel or a bladder. Alternately, each club shaft could be made by winding one or more filaments around the form, or molding each club shaft in a closed die.
The invention is also a method for manufacturing a club shaft. The method includes the steps of: (i) providing a form; (ii) providing at least one pattern; and (iii) wrapping the at least one pattern around the form. Each of the forms can be a mandrel having an elongated cylindrical rod-like structure. Each form includes a form butt section, a form tip section, and a form intermediate section. In order to make the club shaft outlined above, the form intermediate section includes an outer diameter which tapers from the form butt section to the form tip section. Importantly, the rate or amount of taper of the outer diameter varies along the form intermediate section.
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Blau Stephen L.
Chapman Jeanette
Nydegger & Associates
Penley Sports, LLC
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