Sumitomo Rubber Industries Limited

Sri Sports Limited

Other

Dunlop Sports Company Limited

Toyohashi University of Technology

Kaname Yamada

Hyoungchol Kim

Masahide Onuki

Kengo Oka

Takahiro Sajima

Seigou Sakagami

Masatoshi Yokota

Kiyoto Maruoka

Kazuhisa Fushihara

Takeshi Asakura

Jun Nishibayashi

Kohei Takemura

Noritoshi Nakagawa

Shozo Kawamura

Yasuhisa Sekiguchi

Seigo Sakagami

Hiroshi Yoshinaga

A golf ballhas numerous craterson its surface. The cratersare arranged randomly. Of the surface of the golf balla part other than the cratersis a landBy the cratersand the landa rugged pattern is formed on the golf ballA process for designing the rugged pattern includes the steps of:

Process for designing rugged pattern on golf ball surface

On the basis of a surface shape appearing at a predetermined point moment by moment during rotation of a golf ball having numerous dimples on its surface, a data constellation regarding a parameter dependent on a surface shape of the golf ball is calculated. A preferable parameter is a distance between an axis of the rotation and the surface of the golf ball. Another preferable parameter is a volume of space between a surface of a phantom sphere and the surface of the golf ball. Fourier transformation is performed on the data constellation to obtain a transformed data constellation. On the basis of a peak value and an order of a maximum peak of the transformed data constellation, an aerodynamic characteristic of the golf ball is determined. The peak value and the order of the maximum peak are calculated for each of PH rotation and POP rotation.

Golf ball

A golf ballhas a large number of dimplesand a land. A rugged pattern is formed on the surface of the golf ballby these dimplesand the land. These dimplesare arranged in a random manner. Each dimplehas a crater shape. For designing the rugged pattern, a Cellular Automaton method is used. A fluctuation range Rh of the golf ballthat is an index indicating the aerodynamic characteristic during PH rotation is 1.9 mm or less. A fluctuation range Ro of the golf ballthat 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.

Based on a surface shape appearing at a predetermined point moment by moment during rotation of a golf ball having numerous dimples on its surface, a data constellation regarding a parameter dependent on a surface shape of the golf ball is calculated. Preferably, the parameter is a distance between an axis of the rotation and the surface of the golf ball. Another preferable parameter is a volume of space between a surface of a phantom sphere and the surface of the golf ball. Based on a maximum value and a minimum value of the data constellation, a fluctuation range is calculated. By dividing the fluctuation range by a total volume of the dimples, an evaluation value is calculated. This value is calculated for each of PH rotation and POP rotation.

A viscoelastic characteristic value-measuring apparatus, using a split Hopkinson's bar, having an impact bar, input bar, and an output bar. The input bar has a first strain gauge and a second strain gauge. The output bar has a third strain gauge and a fourth strain gauge. The input bar and the output bar are made of a viscoelastic material, and a specimen is in between the input bar and the output bar. The length of said output bar is set to a range from 500 mm to 2500 mm both inclusive. The length of said input bar is set to a range from 1500 mm to 2500 mm both inclusive.

Viscoelastic characteristic value-measuring apparatus and method of measuring viscoelastic characteristic value

A solid golf ball having a polyurethane cover and containing satisfactory formability and ball properties. The golf ball provides good shot feel, controllability, and resilience by adjusting the hardness and the thickness of the polyurethane cover, and the hardness of the entire golf bal. The formability of the polyurethane cover is improved by controlling the amount of residual isocyanate monomer contained in the isocyanate group-terminated urethane prepolymer.

Golf ball having a polyurethane cover

A core is enveloped by a cover with trans 1,4-polyisoprene as the main component, including a super accelerator formed of dithiocarbamate and/or xanthate, and vulcanized at a temperature lower than the melting point of trans 1,4-polyisoprene to provide a golf ball having high impact resilience and spinning performance. Also, a core is enveloped by an inner layer cover having trans 1,4-polyisoprene as the main component, including a super accelerator formed of dithiocarbamate and/or xanthate, and the inner layer cover is surrounded by an outer layer cover with trans 1,4-polyisoprene as the main component, including a super accelerator of an amount larger than that in the inner layer cover to provide a golf ball having high impact resilience and spinning performance, and whose cover material is sufficiently anchored.

Golf ball with core and surrounding cover, and manufacturing method thereof

A golf ball has a spherical surface provided with a plurality of dimples, a parting line extending on a great circle without crossing any of the dimples, and a first great circle, a second great circle and a third great circle dividing the spherical surface into eight spherical equilateral triangles, wherein the parting line crosses six of the eight spherical equilateral triangles, and with respect to each of the first to third great circles, the number of dimples on one side of the great circle is equal to the number of dimples on the other side of the great circle. Further, the golf ball may have the following features: with respect to any of two opposite equilateral triangles which are opposed about the center point of the spherical surface, the arrangement of dimples in one of them and the arrangement of dimples in the other are point-symmetrical about the center point; with respect to any of two adjacent spherical equilateral triangles which have a side in common, the arrangement of dimples in one of them and the arrangement of dimples in the other are not line-symmetrical about the common side; and with respect to any of four adjacent spherical equilateral triangles which have an apex in common, the arrangement of dimples in the four spherical equilateral triangles is not a point-symmetry about the common apex.

The disclosure relates to a dimple arrangement of a golf ball in which 10 to 25 dimples of at least two different diameters are arranged in 24 congruent spherical triangles, respectively consisting of two equal sides and divided by the ridge lines of a complete 24-hedron so that the dimple arrangements in the 24 congruent spherical triangles are identical to each other, and one of the great circle paths formed by connecting the ridge lines with each other coincides with a parting line formed by a pair of hemispherical molds.

An improved golf ball which includes a golf ball main body, and large dimples having a large diameter A and small dimples having a small diameter B which are formed in a large number on the peripheral surface of the golf ball main body. The large and small dimples are provided in the ratio of the diameters A/B within the range of 1.25 to 1.50.

A golf ball having a plurality of different kinds of dimples formed on a spherical surface thereof is disclosed. In one embodiment, a plurality of four different kinds of dimples is formed on the spherical surface of the golf ball. The differences between the kinds of dimples can be a difference in diameter, in depth, or a combination of diameter and depth. The ratio of the product of the diameter and the depth of the largest dimple, to the product of the diameter and depth of the smallest dimple, is in the range of 1.5 to 2.0. Smooth portions are formed on the remainder of the spherical surface to such a size that a dimple having an area larger than an average area calculated from the respective areas of each kind of dimple constituting the plurality of different kinds cannot be formed. The total number of dimples ranges from 300 to 560, and there is a maximum of one great circle zone not traversing a part of any dimple.

Growing community of inventors

Kobe, Japan

Kaname Yamada