Sumitomo Rubber Industries Limited

Sri Sports Limited

Dunlop Sports Company Limited

Seiji Hayase

Masahide Onuki

Naruhiro Mizutani

Daisuke Kohno

Takashi Nakano

Kenji Takasu

Takashi Nakamura

Masahiko Ueda

Yasushi Sugimoto

Naoyoshi Ueda

Wataru Kimizuka

Yuki Motokawa

Yohei Ozaki

Akio Yamamoto

Takahiro Shigemitsu

Hidetaka Inoue

Tomoya Hirano

A golf club head having a hollow portion therein, the head includes a face portion, and a main body including a crown portion and a sole portion each extending backwardly from the face portion. The main body is provided with at least one slit that penetrates the main body and extends in a head-front-back direction. The at least one slit includes a pair of slit inner walls extending in the head-front-back direction and at least one joint connecting the pair of slit inner walls to each other.

Golf club head and method for manufacturing the same

A golf club head is provided with a hollow therein and comprises a face portion, a crown portion, a sole portion, a toe and a heel. One of or each of a toe side and a heel side of the crown portion is provided with a first rigidity-decreasing part which is a groove or a slit and extends in a front-rear direction of the head.

Golf club head

A golf club head with a hollow therein comprises a face portion and a main body portion including a crown portion and a sole portion extending rearward from the face portion. The main body portion is provided with at least one slit penetrating through the main body portion. The slit has a width in the toe-heel direction and a length in the front-rear direction which is larger than the width. The surrounding area of the slit is at least partially provided with a thick portion.

A golf club head having a cavity therein comprises a wall at least a part of which is formed as a convexo-concave wall portion. The convexo-concave wall portion is composed of convexed portions repeatedly arranged in a first direction and a second direction intersecting the first direction, and concaved portions formed between the convexed portions. Each of the convexed portions includes at least one first protrusion extending in the first direction and at least one second protrusion extending in the second direction.

A golf club head includes a striking face, a crown and a sole. The crown and/or the sole includes an FRP member formed by a fiber reinforced plastic that contains a fiber and a matrix resin. The FRP member has an average flexural modulus of greater than or equal to 25 GPa. The fiber may contain a carbon fiber. The carbon fiber may have a tensile elastic modulus of greater than or equal to 300 GPa. The fiber may contain a metallic fiber. The FRP member may have a resin content of less than or equal to 40% by weight. The matrix resin may have a glass transition temperature of higher than or equal to 150&#xb0; C.

A golf clubincludes a head, a shaft, and a grip. The clubhas a forward club flex of greater than or equal to 170 mm. The forward club flex is measured for a golf club in the completed state. The weight of the head is denoted by Wh, and the weight of the club is denoted by Wc. Wh/Wc is greater than or equal to 0.72. With the golf club, a force acting on the player's body during a swing can be reduced. The golf clubcan stabilize swing.

Golf club

A golf clubincludes a head, a shaft, and a grip. A club inertia moment about a swing axis is defined as Isw. A club inertia moment about a grip end is defined as Ige. Ige is 2760 (kg&#xb7;cm) or greater and less than 2820 (kg&#xb7;cm). Isw/Ige is equal to or less than 2.42. A club weight is defined as Wc (kg), an axial direction distance from the grip end to a center of gravity of the club is defined as Lc (cm), and a club inertia moment about the center of gravity of the club is defined as Ic (kg&#xb7;cm). Isw is calculated by Equation (1) below. Ige is calculated by Equation (2) below.&#xd7;(+60)&#x2003;&#x2003;(1)&#xd7;()&#x2003;&#x2003;(2)

A golf club head includes a striking face, a crown and a sole. The crown and/or the sole includes an FRP member formed by a fiber reinforced plastic that contains a fiber and a matrix resin. The head has one or more characteristic mode shapes each having a natural frequency of 3000 Hz or greater and 5000 Hz or less. Of the one or more characteristic mode shapes, one characteristic mode shape that has a largest amplitude of a center of figure of the FRP member is defined as a specific characteristic mode shape, the specific characteristic mode shape has a frequency that is defined as a specific modal frequency, and the specific modal frequency has a modal damping ratio that is defined as a specific modal damping ratio. The specific modal damping ratio of the head is less than or equal to 0.6%.

A golf club includes a head, a shaft, and a grip. The golf club has a club vibration frequency of less than or equal to 210 cpm. The golf club has a swing weight of greater than or equal to D. With the golf club, a force acting on the player's body during a swing can be reduced. The golf club can stabilize swing.

An object of the present invention is to provide a golf ball showing a small ratio of a spin rate on driver shots to a spin rate on approach shots. The present invention provides a multi-piece golf ball comprising a spherical center, three or more envelope layers covering the spherical center, and a cover covering the envelope layers, wherein adjacent two envelope layers are formed so as to include a region composed of elements having a hitting deformation ratio of 30% or more, the hitting deformation ratio being obtained by analyzing a specified golf ball model by a finite element method; and the envelope layer which is radially outwardly positioned of the adjacent two envelope layers has a lowest hardness among all the envelope layers.

Multi-piece golf ball

A golf clubincludes a head, a shaft, and a grip. The clubhas a forward club flex of greater than or equal to 140 mm. The forward club flex is measured for a golf club in the completed state. The griphas a weight Wg of less than or equal to 30 g. With the golf club, a force acting on the player's body during a swing can be reduced. The golf clubcan stabilize swing.

A golf clubincludes a head, a shaft, and a grip. A club inertia moment about a swing axis is defined as Isw. A club inertia moment about a grip end is defined as Ige. Ige is 2920 (kg&#xb7;cm) or greater and less than 2970 (kg&#xb7;cm). Isw/Ige is equal to or less than 2.48. A club weight is defined as Wc (kg), an axial direction distance from the grip end to a center of gravity of the club is defined as Lc (cm), and a club inertia moment about the center of gravity of the club is defined as Ic (kg&#xb7;cm). Isw is calculated by Equation (1) below. Ige is calculated by Equation (2) below.&#xd7;(+60)&#x2003;&#x2003;(1)&#xd7;()&#x2003;&#x2003;(2)

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Kobe, Japan

Seiji Hayase