Abstract: An iron head includes a striking face; a backside surface; a sole surface; a hosel; a recess portion provided in an upper portion of the backside surface; a protruding portion provided at a lower portion of the backside surface and projecting backward; a first hollow portion provided on a heel side of the protruding portion; and a second hollow portion disposed on a toe side and inside the protruding portion. The protruding portion includes a middle portion between the first hollow portion and the second hollow portion. The first hollow portion is disposed away from the second hollow portion by a distance gradually increasing from an upper surface of the protruding portion toward the sole surface.

Abstract: A golf club head manufacturing method, including: welding a first reinforcing piece with first thickness to a central portion between a toe and a heel, so as to extend along an edge of a face side of a sole part, the sole part being part of a lower part formed integrally with a side part; welding a second reinforcing piece of second, larger thickness to a central portion between the toe and heel so as to extend along the edge on the face side of the first piece; welding a face part to the first and second pieces from an inner space of the lower part; welding a hosel part to the lower and face parts; welding a crown part to the lower, face and hosel parts; and welding the lower and face parts together from the outside.

Abstract: A golf club head manufacturing method, including: welding a first reinforcing piece with first thickness to a central portion between a toe and a heel, so as to extend along an edge of a face side of a sole part, the sole part being part of a lower part formed integrally with a side part; welding a second reinforcing piece of second, larger thickness to a central portion between the toe and heel so as to extend along the edge on the face side of the first piece; welding a face part to the first and second pieces from an inner space of the lower part; welding a hosel part to the lower and face parts; welding a crown part to the lower, face and hosel parts; and welding the lower and face parts together from the outside.

Abstract: An iron head is provided with a recess portion provided in an upper portion of a backside surface thereof, and a protruding portion provided at a lower portion of the backside surface. A first hollow portion is provided on a heel side from a bottom surface of a recess portion to a sole surface; and a second hollow portion is disposed on a toe side. The first hollow portion and the second hollow portion do not exist behind a sweet area. The first hollow portion and the second hollow portion may be filled with a shock absorber formed of a rubber or an elastomer.

Abstract: An iron head includes a striking face; a backside surface; a sole surface; a hosel; a recess portion provided in an upper portion of the backside surface; a protruding portion provided at a lower portion of the backside surface and projecting backward; a first hollow portion provided on a heel side of the protruding portion; and a second hollow portion disposed on a toe side and inside the protruding portion. The protruding portion includes a middle portion between the first hollow portion and the second hollow portion. The first hollow portion is disposed away from the second hollow portion by a distance gradually increasing from an upper surface of the protruding portion toward the sole surface.

Abstract: This invention provides a method of identifying an antinode of a primary vibration mode of the golf club head having a hollow golf club head having a face portion, a crown portion, a sole portion, and a side portion. A viscoelastic body is to be mounted in at least one of the face portion, crown portion, sole portion, and side portion. The viscoelastic body is mounted in a part of a portion where the viscoelastic body is to be mounted, the part corresponding to an antinode of a primary vibration mode.

Abstract: An iron head is provided with a recess portion provided in an upper portion of a backside surface thereof, and a protruding portion provided at a lower portion of the backside surface. A first hollow portion is provided on a heel side from a bottom surface of a recess portion to a sole surface; and a second hollow portion is disposed on a toe side. The first hollow portion and the second hollow portion do not exist behind a sweet area. The first hollow portion and the second hollow portion may be filled with a shock absorber formed of a rubber or an elastomer.

Abstract: An iron head is provided with a recess portion provided in an upper portion of a backside surface thereof, and a protruding portion provided at a lower portion of the backside surface. A first hollow portion is provided on a heel side from a bottom surface of a recess portion to a sole surface; and a second hollow portion is disposed on a toe side. The first hollow portion and the second hollow portion do not exist behind a sweet area. The first hollow portion and the second hollow portion may be filled with a shock absorber formed of a rubber or an elastomer.

Abstract: A wood-type golf club head includes a metal sole portion, an elastic body and a weight member. At least one recess is defined in the metal sole portion to extend in a front-rear direction over at least half-length of a front-rear length of the sole portion. The elastic body is embedded in the recess. The weight member is fixed to the recess to cover the elastic body. The weight member is flush with the sole portion. A total area of the recess is in a range of 10% to 60% of that of the sole portion.

Abstract: This invention provides a hollow golf club head having a first viscoelastic body made of a first viscoelastic material and a second viscoelastic body made of a second viscoelastic material with a loss coefficient the temperature dependence of which is different from that of a loss coefficient of the first viscoelastic material.

Abstract: A golf club head that includes: a pedestal composed of at least two ribs each having convex portions at both ends and formed on an inner face of the head; a metal weight disposed on the ribs; and a weld bead extending on a surface of the weight between the convex portions, the weight being fixed on the inner face of the head by the weld bead.

Abstract: This invention provides a hollow golf club head including a fixing member which includes a shaft body formed with a threaded portion at one end, and a head portion at the other end of the shaft body, a viscoelastic body having an opening through which the shaft body extends, a recess portion formed in a circumferential wall of the golf club head and in which the viscoelastic body is disposed, and a screw hole formed in a bottom portion of the recess portion and threadably engages with the threaded portion. The viscoelastic body is fixed between the head portion and the bottom portion by threadably engaging the threaded portion with the screw hole.

Abstract: This invention provides a golf club head having a first viscoelastic body made of a first viscoelastic material and a second viscoelastic body made of a second viscoelastic material with a loss coefficient the temperature dependence of which is different from that of a loss coefficient of the first viscoelastic material.

Abstract: This invention provides a golf club head comprising a head main body, a face plate fixed to a front surface side of the head main body to form a face surface, a cavity portion formed in the head main body and open to a face plate side, and a viscoelastic body inserted in a compressed state in a space formed by the cavity portion and the face plate. An end face on the face plate side of a circumferential wall defining the cavity portion comprises a contacting portion contacting with a rear surface of the face plate, and a non-contacting portion spaced apart from the rear surface of the face plate to form a gap communicating with the cavity portion between the non-contacting portion and the rear surface of the face plate.

Abstract: This invention provides a method of identifying an antinode of a primary vibration mode of the golf club head having a hollow golf club head having a face portion, a crown portion, a sole portion, and a side portion. A viscoelastic body is to be mounted in at least one of the face portion, crown portion, sole portion, and side portion. The viscoelastic body is mounted in a part of a portion where the viscoelastic body is to be mounted, the part corresponding to an antinode of a primary vibration mode.

Abstract: This invention provides a golf club head having a viscoelastic body, wherein the viscoelastic body is made by mixing a plurality of types of viscoelastic materials with loss coefficients temperature dependences of which are different.

Abstract: This invention provides a hollow golf club head including a fixing member which includes a shaft body formed with a threaded portion at one end, and a head portion at the other end of the shaft body, a viscoelastic body having an opening through which the shaft body extends, a recess portion formed in a circumferential wall of the golf club head and in which the viscoelastic body is disposed, and a screw hole formed in a bottom portion of the recess portion and threadably engages with the threaded portion. The viscoelastic body is fixed between the head portion and the bottom portion by threadably engaging the threaded portion with the screw hole.