Golf club head

Abstract

A golf club having an increased moment of inertia and improved ball-hitting directionality is provided. A metal hollow golf club head comprises: a face portion; a crown portion; and a sole portion, and when the golf club has a lie angle of 60° with its club head volume being within 470 cm3, a moment of inertia about the axial line centered on the plumb line passing through the golf club head center of gravity is 5000 to 6000 g-cm2. In order to increase the moment of inertia, the thickness of the center portion of the crown portion is reduced by chemical etching, and a mass, including the portion of mass reduction, is positioned in the sole portion on the side of the toe portion; moreover, the separation distance from the center of gravity to the mass is increased.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a golf club head with improved ball-hitting directionality, and more specifically, relates to a golf club head having a large moment of inertia and improved stability of direction of a hit ball.[0003]2. Description of the Related Art[0004]Various improvements have been made to golf clubs, to extend flight distances, and to enable stable hitting of the ball. Flight distances directly affect scores, and so through improvements so as to broaden the effective range (“sweet” area) of the striking point on a golf club head (hereafter also simply called a “head”), improvements in the position of the effective area, improvements in the material of the face surface, and similar, the probabilistic ball flight distance has been extended; consequently scores have improved, and players using such heads have found them beneficial. Moreover, in order to improve scores, golf clubs have been sought for w...

AI Technical Summary

Benefits of technology

[0013]An object of the invention is to provide a golf club with an increased moment of inertia of a metal hollow golf club head with large volume, and with improved ball-hitting directionality.

[0014]A further object of the invention is to provide a golf club with an increased moment of inertia of a metal hollow golf club head with large volume without increasing the head mass, and with improved ball-hitting directionality.

[0034]As explained in detail above, a golf club of this invention employs a hollow golf club head, the materials comprised by which are in essence all metals; under the constraints that the head volume be 470 cm3 or less (including a tolerance of 10 cm3), that the head mass be 210 g or less, and that the head characteristic time (CT value) related to the restitution characteristic be 257 μs or less (including a tolerance of 18 μs), a method and conditions were discovered for obtaining a golf club head for which the moment of inertia about the axial line centered on the plumb line passing through the center of gravity of the metal hollow golf club head is in the high range 5000 to 6000 g-cm2. As a result, even when the striking point deviates from the center of the face portion, the direction in which the ball is hit is secured, and stable striking is possible compared with clubs of the prior art, so that as a result there is a strong possibility of improvement of a player's score. Further, because in essence the club head is of metal, satisfactory performance with respect to durability, ball-hitting sound, and other aspects can be obtained.

Problems solved by technology

There is a trend toward larger heads, but the masses of the constituent parts of a head adds up, and the swing balance, which is a criterion for ease of swinging of a club, becomes heavy.

As a result, head masses have in the prior art been no greater than approximately 210 g. That is, given the configuration of the prior art, although heads have tended to increase in size the total mass has been limited, and so excess mass to control the position of the center of gravity, or in other words, excess mass to increase the moment of inertia has in the prior art been limited to approximately 10 g, due to the constraint that the total mass should not be increased.

Further, the hosel portion connected to the shaft is positioned on one end of the face portion, and the weight of this portion is also relatively great.

Due to such constraints, it is extremely difficult to increase the weight or other excess mass so as to increase the moment of inertia.

Thus various measures have been taken to extend the flight distance of golf clubs, but at present club performance remains not entirely satisfactory.

While the technologies described above have represented partial improvements, problems remain, and there is still room for improvement.

Metal hollow golf club heads tend to increase in size, as described above, and if the moment of inertia is increased, the volume tends to increase as well; if the volume is increased while making efforts to limit mass, strength-related problems arise; and so there have been limits to the methods employed in the prior art.

When for example using fiber-reinforced resins as described above, not only do strength-related limits appear, but there are the problems of unsatisfactory ball-hitting sounds and resistance to damage.

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