US Patent 6984180 Golf club head and golf club set

A golf club head is formed by integrally welding a face portion and a back portion with each other. The face portion has a circumferential edge portion in its back surface. The circumferential edge portion is made of a flat surface all over its circumference. In the rear surface of the face portion, the part other than the circumferential edge portion is formed as a recess portion. In the bottom surface of the recess portion, a first bottom surface which is the deepest, a second bottom surface which is the second deepest, a third bottom surface which is the third deepest, and a fourth bottom surface which is the shallowest are formed in descending order. Three ribs are provided vertically to extend through the recess portion.