Games using tangible projectile – Golf – Club or club support
Reexamination Certificate
2000-01-28
2001-12-25
Passaniti, Sebastiano (Department: 3711)
Games using tangible projectile
Golf
Club or club support
C473S345000, C473S349000
Reexamination Certificate
active
06332848
ABSTRACT:
BACKGROUND
The present invention relates generally to the field of golf clubs and more particularly to the manufacture of metal “wood” club heads.
It is well known that accuracy and distance are the two primary concerns when making golf shots with a “wood” type club (hereinafter referred to as “wood” or “woods”), such as a driver or a fairway wood. Accuracy and distance are inter-related in the sense that an accurate shot traveling a shorter distance may still be much closer to the hole than an inaccurate shot traveling a much longer distance. Nevertheless, for the purpose of this discussion distance and accuracy will be treated as distinct.
Maximizing distance requires, among other things, efficient transfer of energy from the club head to the ball at impact. One factor affecting the energy transfer is the material used to make the club head. When making a wood club head from wood, designers select a hard wood, traditionally either persimmon or laminated maple, and more recently have provided metallic strike face inserts to increase energy transfer. Recent improved manufacturing techniques have allowed construction of hollow woods made entirely of metal, particularly of titanium and stainless steel, providing marked improvements over their wooden counterparts. Even though improved, hollow metal woods can experience a certain amount of uncontrolled deformation away from the strike face, especially in the larger oversize heads, which can contribute to degrading the club head/ball energy transfer.
Another factor affecting distance is the “loft” of the club, which determines the trajectory of the ball after impact. There are several factors that determine the “loft” or trajectory of a ball upon impact. The first is the loft angle. It is readily apparent that a larger loft angle will result in a higher trajectory. The location the club head's center of mass relative to that of the ball, measured vertically up from the sole plate also affects the trajectory. All else being equal, a club head with a lower center of mass will result in a higher trajectory. If the center of mass of the club head is above that of the ball, it will produce a much lower trajectory and the ball will carry much less distance. Another factor affecting trajectory is the dynamic loft which, among other things, is determined by shaft flexibility and location the club head's center of mass measured horizontally from the club face. The average player has difficulty obtaining the desired ball trajectory, and thus difficulty in achieving the desired distance, when using a driver or other wood club because these clubs have traditionally had a relatively small loft angle high and forward center of mass.
A factor affecting accuracy is the resistance of the club head to rotate about a vertical axis passing through the club head's center of mass, otherwise known as the moment of inertia. For example, the dynamic forces generated through the swing result in torque being applied to the shaft which can result in excessive opening of the club face. Also, if at impact the ball strikes on line with the center of mass there will be little or no twisting about this point. However, if as in many cases, the ball strikes off the center of mass towards the heel or toe of the club head, the club head will tend to rotate about the center of mass imparting side spin to the ball causing it to stray from its intended path. Light weight, high strength materials, such as titanium, have enabled club manufacturers to increase the size of the club head, thereby increasing the moment of inertia of the club head and to some extent addressing these difficulties. Oversized club heads have unquestionably done very well in the market place.
Different designs have been attempted to address various aspects of the difficulties described above. For example, U.S. Pat. No. 5,720,674 discloses a golf club head with a high density peripheral strip around the club head behind the strike face. It is asserted in the disclosure that the arrangement combines “the effect of stabilization during rotation and dynamic loft.” In another design, disclosed in U.S. Pat. No. 5,785,605, an oversized metal wood head is disclosed in which recesses are positioned in the bottom wall in order to add “bottom wall strength and stiffness.” Another club which is available on the market, the “Crane Magic Wand”, attempts to address some of the previously discussed deficiencies by positioning a weight on the back of a relatively large club head.
In spite of the various attempts, the prior art has not achieved a head design which successfully combines the various aspects of club performance. There thus remains a need in the art for a hollow metal wood club with improved moment of inertia, energy transfer and dynamic loft achieved without otherwise significantly altering overall mass or excessively increasing the volume of the club head.
SUMMARY OF THE INVENTION
An embodiment of the present invention which addresses the need in the art comprises a metal wood club head with a body having a crown a sole, a skirt and a strike face. The sole has a first cavity located rearwards and towards the heel of the club head and a second cavity located rearwards towards the toe of the club head and approximately opposite of the first cavity. The two cavities define a relatively flat ridge or land area extending from the front of the sole rearwards. The sole within the two cavities can be made relatively thin allowing removal of mass from the sole. A backweight is attached to the rear most position of the body portion. The backweight facilitates redistribution of mass removed from other areas of the head to the rear-most position. The redistribution of the mass rearwards increases the dynamic loft and moment of inertia of the club head. A concave depression in the sole may be provided directly rearwards of the ridge, as a rearward boundary to the land area which in combination with the two cavities define a beam-like configuration that stiffens the sole along an axis perpendicular to the strike face. Preferably the backweight is positioned substantially in line with the beam-like ridge to facilitate energy transfer to the strike face. Additionally, two approximately oval shaped dimples may be provided on the crown, located rearwards on the crown and opposite each other, thus defining an approximately hour glass shaped spine extending forward from the backweight to just past approximately midway of the top surface. The two dimples and the approximately hour glass shaped spine also help to stiffen the crown along an axis perpendicular to the strike face.
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Crow Thomas L.
Long D. Clayton
Cobra Golf Incorporated
Passaniti Sebastiano
Pennie & Edmonds LLP
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