Golf club head

Abstract

A golf club head with a cavity therein comprises a face portion having a club face for striking a ball, a crown portion, a sole portion, a toe and a heel. The club face comprises a central part including a face center, and a transitional part outside the central part. The central part has a constant thickness and a surface area of not less than 100 sq.mm. The transitional part annularly surrounds the central part. The thickness of the transitional part increases from the central part toward the crown portion, sole portion, toe and heel. The maximum thickness of the transitional part is larger than the thickness of the central part.

1 . A golf club head provided with a cavity therein, comprising:
 a face portion having a club face for striking a ball, a crown portion, a sole portion, a toe and a heel, wherein   the club face comprises a central part including a face center, and a transitional part formed outside the central part,   the thickness of the face portion in the central part is constant,   the surface area of the central part is not less than 100 sq.mm,   the transitional part is continuous to the central part and is formed to annularly surround the central part,   the thickness of the face portion in the transitional part increases from the central part toward the crown portion, the sole portion, the toe and the heel, and   the maximum thickness of the face portion in the transitional part is larger than the thickness of the face portion in the central part.   
     
     
         2 . The golf club head according to  claim 1 , wherein
 the club face further includes a peripheral part outside the transitional part,   the peripheral part continuously or intermittently surrounds the transitional part, and   the thickness of the face portion in the peripheral part is smaller than the thickness of the face portion in the central part.   
     
     
         3 . The golf club head according to  claim 2 , wherein
 the peripheral part continuously surrounds the transitional part.   
     
     
         4 . The golf club head according to  claim 1 , wherein
 the thickness of the face portion in the central part is in a range from 2.5 to 3.0 mm.   
     
     
         5 . The golf club head according to  claim 1 , wherein
 the surface area of the central part is a range from 5% to 10% of the surface area of the face portion.   
     
     
         6 . The golf club head according to  claim 2 , wherein
 the surface area of the central part is a range from 5% to 10% of the surface area of the face portion.   
     
     
         7 . The golf club head according to  claim 3 , wherein
 the surface area of the central part is a range from 5% to 10% of the surface area of the face portion.   
     
     
         8 . The golf club head according to  claim 4 , wherein
 the surface area of the central part is a range from 5% to 10% of the surface area of the face portion.   
     
     
         9 . The golf club head according to  claim 1 , wherein
 the central part has an elliptical or oblong contour line which is longer in the toe-heel direction than in an up-down direction.   
     
     
         10 . The golf club head according to  claim 2 , wherein
 the central part has an elliptical or oblong contour line which is longer in the toe-heel direction than in an up-down direction.   
     
     
         11 . The golf club head according to  claim 3 , wherein
 the central part has an elliptical or oblong contour line which is longer in the toe-heel direction than in an up-down direction.   
     
     
         12 . The golf club head according to  claim 8 , wherein
 the central part has an elliptical or oblong contour line which is longer in the toe-heel direction than in an up-down direction.   
     
     
         13 . The golf club head according to  claim 1 , wherein
 the transitional part includes a first transitional part annularly surrounding the central part, and   the thickness of the face portion in the first transitional part increases continuously from the central part toward the crown portion, the sole portion, the toe and the heel.   
     
     
         14 . The golf club head according to  claim 13 , wherein
 the transitional part includes a second transitional part continuous to the first transitional part on the toe side thereof, and   the second transitional part extends in a toe-heel direction with a constant thickness of the face portion.   
     
     
         15 . The golf club head according to  claim 14 , wherein
 the transitional part includes a third transitional part continuous to the first transitional part on the heel side thereof, and   the third transitional part extends in the toe-heel direction with a constant thickness of the face portion.   
     
     
         16 . The golf club head according to  claim 2 , wherein
 the thickness of the face portion in the peripheral part is in a range from 2.1 to 2.9 mm.   
     
     
         17 . The golf club head according to  claim 2 , wherein
 the peripheral part includes a crown side peripheral part continuous to the transitional part on the crown side thereof, and a sole side peripheral part continuous to the transitional part on the sole side thereof, and   the thickness of the face portion in the sole side peripheral part is smaller than the thickness of the face portion in the crown-side peripheral part.   
     
     
         18 . The golf club head according to  claim 16 , wherein
 the peripheral part includes a crown side peripheral part continuous to the transitional part on the crown side thereof, and a sole side peripheral part continuous to the transitional part on the sole side thereof, and   the thickness of the face portion in the sole side peripheral part is smaller than the thickness of the face portion in the crown-side peripheral part.   
     
     
         19 . The golf club head according to  claim 17 , wherein
 the peripheral part includes a toe side peripheral part continuous to the transitional part on the toe side thereof, and a heel side peripheral part continuous to the transitional part on the heel side thereof, and   the thickness of the face portion in the toe-side peripheral part and the thickness of the face portion in the heel-side peripheral part are smaller than the thickness of the face portion in the crown-side peripheral part.   
     
     
         20 . The golf club head according to  claim 18 , wherein
 the peripheral part includes a toe side peripheral part continuous to the transitional part on the toe side thereof, and a heel side peripheral part continuous to the transitional part on the heel side thereof, and   the thickness of the face portion in the toe-side peripheral part and the thickness of the face portion in the heel-side peripheral part are smaller than the thickness of the face portion in the crown-side peripheral part.