Abstract: A golf ball 2 includes a core 4, a mid layer 6 positioned outside the core 4, a reinforcing layer 8 positioned outside the mid layer 6, and a cover 10 positioned outside the reinforcing layer 8. The difference between: a JIS-C hardness H(5.0) and a JIS-C hardness Ho at the central point is 6.0 or greater. The difference between: a JIS-C hardness H(12.5) and the hardness H(5.0) is 4.0 or less. The difference between a JIS-C hardness Hs at the surface of the core 4 and the hardness H(12.5) is 10.0 or greater. The difference between the hardness Hs and the hardness Ho is 22.0 or greater. In the golf ball 2, there is no zone in which a hardness decreases from the central point toward the surface. A hardness H2 of the mid layer 6 is greater than a hardness H3 of the cover 10.

Abstract: A head 2 is hollow. The head 2 includes a face part 4, a crown part 6 and a sole part 8. Ribs 20 and 22 are provided on the inner surface of the head. The ribs 20 and 22 have a height being greater than a thickness. The ribs 20 and 22 are separated from the face part, and are separated from the crown part. An extending direction of the rib 20 is inclined with respect to a front-back direction of the head. The rib 20 has a height change part 30 formed in a face side end part of the rib 20, the height change part 30 having a height gradually lowered as approaching a rib end part. The rib 20 extends toward a heel side in the direction of a backside of the head.

Abstract: An adjustable golf club incorporates instructions into the golf club, and more particularly, in connection with the club head. More specifically, encoded information is visibly provided on the club head, the encoded information relating to the performance of the club head. In addition to the encoded information, a decoder or device for interpreting the encoded performance information is also provided on the club head. The encoded information, in conjunction with the decoder, allows the golfer to easily adjust his or her club head based on playing conditions or his or her swing. Typically, the encoded information relates to a weight of the club head, and may be used to vary the weight of the club head. A method of configuring a putter-type golf club head adaptable to a plurality of configurations is described, as well as a kit for selectively configuring components of a golf club head.

Abstract: A golf ball 2 has a core 4, an inner cover 6 positioned outside the core 4 and an outer cover 8 positioned outside the inner cover 6. The core 4 has a spherical center 10 and a mid layer 12 positioned outside the center 10. The center 10 has a diameter of 1 mm or greater and 15 mm or less. A difference (H4?H3) between a JIS-C hardness H4 of a surface of the core and a JIS-C hardness H3 of an innermost part of the mid layer is equal to or greater than 10. The hardness H4 is greater than a JIS-C hardness H2 of a surface of a spherical body including the core 4 and the inner cover 6. A Shore D hardness H7 of the outer cover 8 is less than 40.

Abstract: An object of the present invention is to provide a novel golf ball that controls the spin rate on the approach shots while suppressing the change in the spin rate on the driver shots and a method for producing the same. The present invention provides a golf ball having a cover containing a resin component and a filler, wherein the filler is oriented roughly parallel to a surface of the cover. The cover having anisotropy behaves like a hard material against the deformation in the compression direction on the driver shots and behaves like a soft material against the deformation in the shear direction on the approach shots. The present invention also provides a method for producing a golf ball, comprising compression molding a cover composition containing a resin component and a filler to mold a shell, and compression molding a core covered with a plurality of shells to mold a cover.

Abstract: Various exemplary implementations of the principles described herein provide a cover for a golf club. The golf club may include a head and a shaft, the head having a heel end and a toe end, and the shaft connected at the heel end. The cover may include a toe portion substantially shrouding the toe end of the club head and a heel portion substantially shrouding the heel end of the club head and a first length of the shaft. The cover may include a sleeve portion extending from the heel portion and substantially shrouding a second length of the shaft, the second length being greater than the first length. The sleeve portion may have an opening opposite the heel portion. The cover may include a first pull member on the heel portion.

Abstract: A golf club head according to one or more aspects of the present invention may include a face portion or strike-face wall comprising a top inner boundary, an intermediate inner boundary, and a bottom inner boundary having a bottom-inner-boundary toe portion and a bottom-inner-boundary heel portion. The strike-face wall may further include a first uniform-thickness region, adjoining the top inner boundary, and a variable-thickness region adjoining the uniform-thickness region and a majority of the bottom inner boundary. In another example, the variable-thickness may adjoin a majority of the top inner boundary and the uniform-thickness region may adjoin a majority of the bottom inner boundary.

Abstract: A method for measuring behavior of a head of a golf club and of a ball includes obtaining two-dimensional data of three or more marks on a face surface at two points in time before impact; identifying three-dimensional positions of the marks on the two points in time from the two-dimensional data; identifying behavior of the face surface of the three-dimensional position of each mark at the two points in time; identifying time of a contact of the face surface with the ball; estimating behavior of the head at the time of contact of the face surface with the ball; obtaining two-dimensional data of the ball at the two points in time; identifying three-dimensional position and posture of the ball at the two points in time; and estimating a behavior value of the ball from the three-dimensional position and posture of the ball.

Abstract: A golf club head includes a striking face having a face center, a bottom portion, a top portion including an exterior surface, a hosel including an imaginary vertical hosel plane, a forwardmost point, and a rearwardmost point. In an imaginary vertical plane perpendicular to the hosel plane and passing through the face center, the exterior surface includes a path having a first point and a second point rearward of the first point. An imaginary infinite straight line passes through the first point and the second point, but does not penetrate the exterior surface. A segment of the imaginary straight line is delimited by the first point and the second point. A maximum distance between the segment and the exterior surface of the top portion is no greater than 0.70 mm and a distance between the first point and the second point is no less than 22 mm.

Abstract: An object of the present invention is to provide a golf ball material producing a high spin rate on approach shots and a low spin rate on driver shots and a golf ball using the same. The present invention provides a golf ball material having a ratio [Shore D/log(bending stiffness)] of Shore D hardness to a logarithm of bending stiffness (kgf/cm2) of 19.0 or more.

Abstract: A golf club has a reverse flex of 110 to 160 mm. The face portion includes a central thick part, a toe-crown-side thin part on a crown-side and on a toe-side of the central thick part, and a heel-sole-side thin part on a sole-side and on a heel-side of the central thick part. In the front view of the head, a first straight line passing an area centroid of the toe-crown-side thin part and an area centroid of a back surface of the face portion has an angle ?A of 10 to 30 degrees, and a second straight line passing an area centroid of the heel-sole-side thin part and the area centroid of the back surface of the face portion has an angle ?B of 36 to 40 degrees, each with respect to the horizontal plane.

Abstract: A golf club head has a striking face with a plurality of scorelines including a first scoreline and a second scoreline adjacent thereto. The striking face also has a plurality of auxiliary grooves each spaced from the scorelines. In a first imaginary vertical plane, a first path is formed by a first intersection between the first imaginary vertical plane and the striking face, and the auxiliary grooves have a first concentration no less than 0.17 measured between the first and second scorelines. A second imaginary vertical plane is horizontally spaced from the first imaginary plane. A second path is formed in the second imaginary vertical plane by a second intersection between the second imaginary vertical plane and the striking face. The auxiliary grooves in the second imaginary vertical plane have a second concentration that is different from the first concentration measured between the first and second scorelines.

Abstract: Golf ball 2 has a land and numerous dimples 8 on the surface thereof. This dimple 8 has first curved face 14 and second curved face 16. The first curved face 14 is continuous with land 10 at the edge Ed. The second curved face 16 is continuous with the first curved face 14 at the boundary point Pb. The first curved face 14 has ring-shape. The first curved face 14 is projecting upwards. The second curved face 16 has a bowl-shape. The second curved face 16 is projecting downwards. The second curved face 16 has a curvature radius R2 of equal to or greater than 10 mm. The proportion P1 of the depth d1 of the boundary point Pb to the depth de of the dimple 8 is 1% or greater and 10% or less. The mean diameter of the dimple 8 is equal to or greater than 4.0 mm. The proportion P3 of the number of the dimples 8 having a diameter of equal to or greater than 4.3 mm to total number of the dimples 8 is equal to or greater than 30%.

Abstract: An object of the present invention is to provide a golf ball resin composition with an excellent resilience and fluidity. Another object of the present invention is to provide a golf ball resin composition with a high hardness and durability. Yet another object of the present invention is to provide a golf ball traveling a great distance with an ionomer cover. The present invention provides a golf ball resin composition comprising, (A) an ionomer resin consisting of a metal ion-neutralized product of a binary copolymer composed of an olefin and an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms; (B) a binary copolymer composed of an olefin and an ?,?-unsaturated carboxylic acid having 3 to 8 carbon atoms, and (C) a zinc compound, wherein a content ratio ((A)/(B)) of (A) component to (B) component ranges from 50/50 to 80/20 in a mass ratio and a content of (C) component ranges from 0.

Abstract: Golf ball 2 has spherical core 4 and cover 6 provided so as to cover this core 4. The core 4 has spherical center 8 and mid layer 10 provided so as to cover this center 8. The resilience coefficient Ec of the center 8, the resilience coefficient Em of the core 4 and the resilience coefficient Eb of the golf ball 2 satisfy the following formulae (1) and (2): Ec>Eb?Em??(1); Eb?Em?Ec?Eb??(2). The difference (Eb?Em) between the resilience coefficient Eb and the resilience coefficient Em is equal to or greater than 0.004. The difference (Ec?Eb) between the resilience coefficient Ec and the resilience coefficient Eb is equal to or greater than 0.004.

Abstract: A golf club head having a good feel of hitting a ball, comprising a head body 1A having a face 2 for hitting a ball on a front side of the head body and having at least one recess portion 10 in an outer surface 1S thereof except the face 2, and at least one vibration absorbing member made of a viscoelastic material and disposed in the recess portion 10, the recess portion 10 including a bottom surface 10a and a sidewall surface 10b extending from the bottom surface 10a to the outer surface 1S, and the vibration absorbing member 11 being fixed to the bottom surface 10a to provide a free vibration portion 11A extending up to a position corresponding to the outer surface 1S of the head body 1A without coming into contact with the sidewall surface 10b of the recess portion 10.

Abstract: A designing method of the present invention includes the steps of: measuring a golf swing to obtain a measured result; obtaining a swing model provided with a link model and joint torque data based on the measured result, the link model having at least two links; performing simulation for swing the golf club using the swing model; and obtaining head information in a specific situation during a swing based on a result of the simulation. In the designing method, a plurality of specifications of the golf club and/or the plurality of swing models are used to obtain the plurality of head information, and stability is evaluated using a difference between the head information. In the designing method, it was found that a great lateral moment of inertia of a head and a small depth of a center of gravity of the head contribute to the stability.

Abstract: A golf ball 2 includes a core 4, a mid layer 6, and a cover 8. The difference between: a hardness H(5.0) at a point located at a distance of 5 mm from the central point of the core 4; and a hardness Ho at the central point is 6.0 or greater. The difference between: a hardness H(12.5) at a point located at a distance of 12.5 mm from the central point; and the hardness H(5.0) is 4.0 or less. The difference between a hardness Hs at the surface of the core 4 and the hardness H(12.5) is 10.0 or greater. The difference between the hardness Hs and the hardness Ho is 22.0 or greater. In the core 4, there is no zone in which a hardness decreases from the central point to the surface. A hardness H3 of the cover 8 is greater than a hardness H2 of the mid layer 6. The cover 8 is formed from a resin composition containing a polyamide copolymer including a polymerized fatty acid (a-1), sebacic acid and/or azelaic acid (a-2), and a polyamine component (a-3).

Abstract: A method for surface treating a golf club head, includes: (a) forming a depression unit in the golf club head, the depression unit being indented inwardly from an outer surface of the golf club head, the outer surface being divided into a working area and a non-working area, the depression unit being formed in the working area; (b) filling the depression unit with a shielding material and covering the non-working area with a covering material; and (c) sandblasting the golf club head after step (b) and removing subsequently the shielding material from the depression unit and the covering material from the non-working area so as to form the working area into sandblasted and non-sandblasted regions that differ in gloss intensity.

Abstract: A golf ball 2 has a large number of dimples 8 and a land 10. A rugged pattern is formed on the surface of the golf ball 2 by these dimples 8 and the land 10. These dimples 8 are arranged in a random manner. Each dimple 8 has a crater shape. For designing the rugged pattern, a Cellular Automaton method is used. A fluctuation range Rh of the golf ball 2 that is an index indicating the aerodynamic characteristic during PH rotation is 1.9 mm or less. A fluctuation range Ro of the golf ball 2 that is an index indicating the aerodynamic characteristic during POP rotation is 1.9 mm or less. The absolute value of the difference dR between the fluctuation range Ro and the fluctuation range Rh is 0.4 mm or less.