Games using tangible projectile – Golf – Club or club support
Reexamination Certificate
2000-05-23
2001-11-20
Chapman, Jeanette (Department: 3711)
Games using tangible projectile
Golf
Club or club support
C473S289000, C473S318000
Reexamination Certificate
active
06319147
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an iron golf club set composed of a plurality of golf clubs having steel shafts. More specifically, the present invention relates to an iron golf club set adapted to facilitate swinging for the entire club set, particularly realizing easy rising of a ball when it is hit by a longer golf club, and easy control of the direction of a ball when it is hit by a shorter golf club.
For a shaft of an iron golf club, a steel shaft having a steel pipe formed in a tapered shape has been used. As methods used to manufacture steel shafts corresponding to respective counts when an iron golf club set is made using such steel shafts, a stretching process, a chip-cutting process, and so on, have been available.
The stretching process is a method comprising the steps of preparing raw material pipes (base pipes) equal in weight for a plurality of golf clubs; and stretching the raw material pipes until they reach lengths corresponding to respective counts while forming step patterns (node-shaped patterns appearing in shaft axial directions) on outer circumferential surfaces of the raw material pipes by using a plurality of dies different in inner diameters. On the other hand, the chip-cutting process is a method comprising the steps of preparing a plurality of steel shafts stretched to a predetermined length while forming step patterns on outer circumferential surfaces of raw material pipes; and cutting the tip portions of these steel shafts corresponding to the lengths of respective counts such that the steel shafts can be formed to have necessary lengths. Each of the step patterns generally includes a plurality of steps formed at a predetermined interval along the shaft axial direction.
However, in the case of the stretching process, all the steel shafts in the golf club set are constant in mass, the shafts stretched relatively long for the long clubs are thin, and the shafts stretched relatively short for the short clubs are thick. Thus, the long club gives a heavy feeling to a golfer, while the short club gives a light feeling to the golfer. On the other hand, in the case of the chip-cutting process, the shafts for the short clubs are substantially lighter in mass.
If the long golf clubs were felt to be heavy in relative relation, then swinging for the long clubs became difficult, resulting in difficult rising of a ball. If the short golf clubs were felt to be light in relative relation, then controlling of a direction of a ball hit by the short golf club became difficult. As a result, the use of the iron golf club set composed of the plurality of golf clubs made of steel shafts was difficult for those other than professional golfers or highly skilled players.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an iron golf club set adapted to facilitate swinging for all of the clubs in the set, particularly to realize easy rising of a ball when it is hit by a longer golf club, and to make it easy to control the direction of a ball when it is hit by a shorter golf club.
In order to achieve the foregoing object, an iron golf club set of the present invention comprises a plurality of golf clubs of different count, each golf club having a steel shaft, wherein a steel shaft of a shorter golf club is set heavier than that of a longer golf club; a step formation region is formed in a position spaced by a first axial distance from a grip end of a shaft, the first axial distance being equal for all of the golf clubs, the step formation region having differing shaft outer diameters in a plurality of steps therein; a specific area within the step formation region is set in a position spaced by a second axial distance from a sole end of a head in the shaft, the second axial distance being equal for all of the golf clubs, and the specific area is nearer to a grip with respect to a shaft full length of each golf club; and a step interval in the specific area is smaller than that outside the specific area.
By setting the steel shaft of the longer golf club lighter and that of the shorter golf club heavier as described above, swinging of the golf clubs can be facilitated for all of the club sets. In addition, since the specific area is set in the position having an equal distance for all of the golf clubs from the sole end of the head in the shaft axial direction and nearer to the grip with respect to the shaft full length in the step formation region of each golf club, a kick point of the longer golf club can be set in a middle position of the shaft (middle kick point), while a kick point of the shorter golf club can be set nearer to a hand side (high kick point). As a result, easy ball rising can be realized for the longer golf clubs, and easy control of a hit ball direction can be realized for the shorter golf clubs.
Preferably, weights of the steel shafts should be gradually increased from the longer golf club to the shorter golf club, and a weight difference between the steel shaft of the longest golf club and that of the shortest golf club in the club set should be set in a range of 2 to 20 g.
For the step formation region, preferably, a starting end thereof should be set in a range of 65 to 190 mm from the grip end, and a terminating end thereof should be set in a range of 601 to 726 mm from the grip end. On the other hand, for the specific area, preferably, a starting end thereof should be set in a range of 496 to 536 mm from the sole end, and a terminating end thereof should be set in a range of 376 to 416 mm from the sole end. By setting the step formation region and the specific area in the above ranges, a kick point of the longer golf club can be set in a middle position of the shaft (middle kick point), while a kick point of the shorter golf club can be set nearer to the hand side (high kick point).
A step interval in the specific area should preferably be set constant in a range of 20 to 40 mm. More specifically, a length of the specific area in the shaft axial direction should be set in a range of 80 to 160 mm, and the number of steps provided in the specific area should be set in a range of 2 to 4.
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Miura Tadashi
Nakamura Yoshihide
Ono Shinya
Aryanpour Mitra
Chapman Jeanette
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
The Yokohama Rubber Co. Ltd.
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