Patent ID: 8382609
Filing Date: 2013-02-26
Classification: A63B,Y10T

Abstract:
1. A golf club head having a hollow structure comprising a main body member provided with an opening in the front thereof, and a face member closing the opening so as to form a hollow, the face member having a front face forming at least a part of a club face and a rear face facing the hollow, and the face member made of an unidirectionally rolled plate of a titanium alloy having alpha phase crystals and having an aeolotrophy satisfying at least one of (i) the ratio (Spd/Srd) of the tensile strength Spd of the unidirectionally rolled plate in the direction ND, perpendicular to the rolled direction RD to the tensile strength Srd of the unidirectionally rolled plate in the rolled direction RD, is not less than 1.20 and not more an 1.60, and (ii) the ratio (Epd/Erd) of the tensile elastic modulus Epd of the unidirectionally rolled plate in the direction ND, perpendicular to the rolled direction RD to the tensile elastic modulus Erd, of the unidirectionally rolled plate in the rolled direction RD, is not less than 1.10 and not more than 1.60, wherein said rear face is provided with a single ribbed part, extending continuously from a front edge of a crown portion of the head to a front edge of a sole portion of the head through a sweet spot, while defining a part having a substantially constant thickness between the upper end and lower end of the ribbed part, the longitudinal direction of the ribbed part, which is defined as the direction of a straight line drawn between the widthwise center point of the ribbed part at its upper end and the widthwise center point of the ribbed part at its lower end, is inclined at an angle θ the rolled direction of the unidirectionally rolled plate is inclined at an angle of from 5 to 30 degrees with respect to the horizontal direction, and said longitudinal direction of the ribbed part is substantially perpendicular to the rolled direction of the face member, and said rear face is further provided with a toe-side groove (