Patent ID: 7766765

Claim:
A wood-type golf club head having a head volume V (cc) and comprising a hollow metal structure and a separate weight member, the hollow metal structure comprising: a face portion of which front surface defines a club face for hitting a ball, wherein the area S (sq.cm) of the club face and the head volume V (cc) satisfy the following equations S ≧( V× 0.08)+(−5.8), S ≦( V× 0.08+(−1.8), and S≧33, and wherein the weight of the face portion is not less than 20% but not more than 40% of the overall weight of the club head; a crown portion intersecting the club face at the upper edge thereof; a sole portion intersecting the club face at the lower edge thereof; a side portion between the crown portion and sole portion which extends from a toe-side edge to a heel-side edge of the club face through a back face of the club head; and a hosel portion protruding upward from the crown portion and provided at the upper end thereof with a shaft inserting hole, wherein said hollow metal structure is composed of a head main body made of a metal material, and a face plate made of a metal material and disposed at the front of the head main body to form at least a major part of said face portion, the head main body is formed by casting and provided at the front with an opening, and the face plate is formed from a rolled titanium alloy and fitted in the opening and welded to the head main body with the edges of the face plate and the opening confronting each other and the back face of the face plate facing the hollow, whereby said major part of the face portion is composed of a single layer of the titanium alloy, said separate weight member has a larger specific gravity than the head main body and a mass of not less than 1 grams but not more than 40 grams, and wherein in a zone (L 1 , L 2 , L 3 ) defined as extending backward from the edge of the club face for a distance in a range of from 30 to 60 mm along an outer surface of the club head, said outer surface is curved with a radius (Rt, Rc, Rs) of curvature progressively decreasing towards the club face, and said zone is provided in at least one of the crown portion, the sole portion and a toe-side part of the side portion, wherein in the case that the zone (L 1 ) is provided in the toe-side part of the side portion, with respect to the contour of the club head in the top view of the club head, the radius (Rt) of curvature of said curved outer surface is not less than 3 mm but not more than 60 mm, in the case that the zone (L 2 ) is provided in the crown portion, in a cross section of the club head including the center of gravity of the head and a sweet spot on the club face, the radius (Rc) of curvature is not less than 3 mm but not more than 100 mm, and in the case that the zone (L 3 ) is provided in the sole portion, in a cross section of the club head including the sweet spot and the center of gravity, the radius (Rs) of curvature is not less than 3 mm but not more than 100 mm.