Sri Sports Limited

Dunlop Sports Company Limited

Sumitomo Rubber Industries Limited

Takeshi Ashino

Kunio Niwa

Hiroyuki Takeuchi

To provide a golf club head excellent in hitting sound and flight distance performance. A head includes a face, a crown and a sole. The crown has an inner surface on which grid-form rib is provided. When a region on which the grid-form rib is provided is defined as a rib region, an additional rib is further provided on the rib region. The additional rib is positioned on a heel side relative to a face center. Preferably, the grid-form rib is formed by intersection of first ribs extending in a substantially toe-heel direction and second ribs extending in a substantially face-back direction. Preferably, the additional rib is sloped to be closer to a back side as approaching to the heel side.

Golf club head

A golf club head according to the present invention includes a face portion, a sole portion, and a crown portion. The face portion has a central region, a toe region arranged on the toe side with respect to the central region in the toe-heel direction, and a heel region arranged on the heel side with respect to the central region in the toe-heel direction. The central region is formed with a higher thickness than the toe region and the heel region. The toe region and the heel region have multiple reduced-thickness portions that are arranged at intervals in the toe-heel direction and extend from the sole portion side to the crown portion side.

A golf club set comprises golf clubs with different club lengths, each golf club comprising a hollow golf club head, the golf club head with a face portion having a clubface for hitting a ball, the face portion comprising a central thicker portion, a toe-side thinner portion with a thickness smaller than that of the central thicker portion, and a heel-side thinner portion with a thickness smaller than that of the central thicker portion, wherein in a front view of the club head under a standard state, the toe-side thinner portion is provided so that a centroid thereof is placed upward than a center of the clubface, the heel-side thinner portion is provided so that a centroid thereof is placed downward than the center of the clubface.

Golf club set

A racket frameof the present invention includes fiber reinforced resinous layers. At least one of the fiber reinforced resinous layers is a layer (L) in which a rubber component is blended. A matrix of the layer (L) contains a rubber component. When a total weight of a matrix contained in the racket frameis defined as Wm (g) and a total weight of the rubber component contained in the frameis defined as Wg (g), a rate Rg (%) of the total weight Wg to the total weight Wm is 2.5(%) or greater and 17.5(%) or less. In this frame, a ratio [Rh/Rs] of plane rigidity Rh to throat rigidity Rs is 0.05 or greater and 0.2 or less. Preferably, the plane rigidity Rh is 30 (kgf/cm) or greater and 70 (kgf/cm) or less. Preferably, the throat rigidity Rs is 250 (kgf/cm) or greater and 800 (kgf/cm) or less.

Racket frame

A racket including a string-stretching part for forming a ball-hitting face by tensionally mounting strings in string holes, formed through the string-stretching part, in which grommets are mounted respectively. As the grommets, a double-tubular grommet is mounted in at least one of the string holes. The double-tubular grommet is formed as an integrally molded article, including an inner tubular portion having a string insertion hole through which the string is inserted with the string in contact with the string insertion hole and pulled from an inward-end open portion thereof or an outward-end open portion thereof; an outer tubular portion fitted in the string hole formed through the string-stretching part with the outer tubular portion spaced at a certain interval from the inner tubular portion; and a base portion integrally connected with an outward-side end of the inner tubular portion and that of the outer tubular portion and disposed on a peripheral surface of the string-stretching part.

Racket

In a racket frame, a yoke part is disposed between left and right portions of a bifurcated throat part continuous with a head part and with a shaft part. A ball-hitting face is formed with the yoke part and the head part. The head part and the yoke part have a plurality of string holes formed in penetration therethrough to insert longitudinal and transverse strings therethrough. Longitudinal string holes formed outside left and right sides of the yoke part connected with the left and right portions of the throat part are extended to the throat part to form extended longitudinal string holes open on an outer surface of the throat part.

A tennis racket frame is composed of a laminate of prepregs each containing carbon fibers serving as a reinforcing fiber thereof. At least one part of layers of the laminate is formed as a hard layer consisting of a prepreg composed of the reinforcing carbon fibers and a hard carbon film (DLC film) formed on the surface of the carbon fibers.

Tennis racket frame

A tennis racket having a racket frame defining a ball-hitting face, wherein if the upper part of the ball-hitting face is set as a 0-degree position, a string protection member is mounted on at least one portion of a head part of the racket frame in a range from a clockwise 45-degree position to a clockwise 135-degree position and in a range from a clockwise 225-degree position to a clockwise 315-degree position by interposing a viscoelastic member between the string protection member and the racket frame. The moment (Is) of inertia of the tennis racket in a swing direction is set to not less than 450,000 g/cmnor more than 490,000 g/cm, when strings are not tensionally mounted thereon. The moment (Ic) of inertia of the tennis racket in a center direction is set to not less than 15,000 g/cmnor more than 19,000 g/cm, when the strings are not tensionally mounted thereon.

Tennis racket

In a tennis racket having a racket frame composed of a fiber reinforced resin, the moment of inertia Ic of the tennis racket in a center direction thereof is set to not less than 13000 g&#xb7;cmnor more than 17000 g&#xb7;cm, the moment of inertia Ig around a center of gravity thereof is set to not less than 80000 g&#xb7;cmnor more than 200000 g&#xb7;cm, and the moments of inertia Ic and Ig are so set as to satisfy a relationship expressed by [30&#xd7;(Ic)&#x2212;(Ig)]/10000&#x2267;31.

A racket frame including a first laminate composed of a plurality of first prepregs consisting of fiber reinforced resin and a second prepreg, consisting of fiber reinforced resin, which is layered on the first laminate. The first laminate has a loss factor (=tan &#x3b4;) set to not less than 0.005 nor more than 0.02, when the loss factor is measured at a temperature of 10&#xb0; C. and a frequency of 10 Hz. The second prepreg has a loss factor (=tan &#x3b4;) set to not less than 0.10 nor more than 0.50, when the loss factor is measured at a temperature of 10&#xb0; C. and a frequency of 10 Hz.

A tennis racket frame (), including a sleeve composed of a fiber reinforced resin, having a weight not less than 180 g nor more than 270 g, when strings are not mounted in a ball-hitting face thereof surrounded with a head part thereof. Supposing that the strings are not mounted in the ball-hitting face, a secondary natural frequency (F) of the racket frame in an in-plane direction thereof is set to not less than 200 Hz nor more than 320 Hz, a secondary natural frequency (F) thereof in an out-of-plane direction thereof is set to not less than 480 Hz nor more than 650 Hz, and F/Fis set to not less than 0.3 nor more than 0.6.

A racket frame () including a laminate having not less than two fiber reinforced resinous layers layered one upon another and one or more modified fiber reinforced resinous layers () each containing a modified resinous composition, as a matrix resin, having a loss factor (=tan &#x3b4;) not less than 0.5 nor more than 3.0, when the loss factor is measured at a temperature of 0&#xb0; C. to 10&#xb0; C. and a frequency of 10 Hz. A weight of the modified fiber reinforced resinous layers () is set to not less than 1% nor more than 10% of a weight of the fiber reinforced resinous layers.

A racket frame ( ) has a pipe-shaped racket-frame body ( ) made of a fiber reinforced resin and composed of a head ( ), a throat part ( ), a shaft part ( ), and a grip part ( ) sequentially arranged and a yoke ( ) connected to the racket-frame body ( ). In this construction, supposing that the head ( ) is a clock face and that the top position of the head ( ) is 12 o'clock, a yoke rigidity value at a central position P , vertical to a ball-hitting face (F), of the yoke ( ) in a longitudinal direction thereof is in a range of 10% to 70% of a face rigidity value which is an average of a rigidity value at a 12 o'clock position (P ) vertical to the ball-hitting face (F) and a rigidity value at a three o'clock position (P ) vertical to the ball-hitting face (F).

Racket with reduced yoke rigidity

A frame body ( ) is formed separately from a yoke ( ) connecting right and left parts of the frame body ( ) to each other. The yoke ( ) and the frame body ( ) are connected to each other by a mechanical connection means, with both ends of the yoke ( ) in contact with the right and left parts of the frame body ( ) in an area of not less than 10 cm (1.6 in ). A shear force generated when the racket frame ( ) deforms is collectively applied to a connection surface of the frame body ( ) and that of the yoke ( ) to increase a vibration-damping performance of the racket frame ( ).

Growing community of inventors

Hyogo, Japan

Takeshi Ashino