Sri Sports Limited

Dunlop Sports Company Limited

Sumitomo Rubber Industries Limited

Toyohashi University of Technology

Hyoungchol Kim

Masahide Onuki

Takahiro Sajima

Kaname Yamada

Hirotaka Nakamura

Kohei Mimura

Keiji Moriyama

Kazuhiko Isogawa

Seiichiro Endo

Shozo Kawamura

A golf ball has, on a surface thereof, a rugged pattern composed of a land and a large number of dimples. A method for designing the rugged pattern includes the steps of: (1) assuming a large number of circles on a surface of a phantom sphere; (2) assuming a large number of generating pointsbased on positions of the large number of circles; (3) assuming a large number of Voronoi regionson the surface of the phantom sphere by a Voronoi tessellation based on the large number of generating points; and (4) assigning a dimple and a land to the surface of the phantom sphere based on contours of the large number of Voronoi regions

Process for designing rugged pattern on golf ball surface

A golf ballhas a large number of dimpleson a surface thereof. The contours of the dimplesare non-circular. A standard deviation of areas of the dimplesis equal to or less than 1.7 mm. A ratio of a total area of the dimplesrelative to a surface area of a phantom sphere of the golf ballis equal to or greater than 80%. By comparting lines CS obtained by projecting sides of a regular dodecahedron, which is inscribed in the phantom sphere, onto the phantom sphere, a surface of the phantom sphere can be divided into 12 units Ut each of which meets the following mathematical formula (I):&#x2212;2&#x2266;(/12)&#x2212;&#x2266;2&#x2003;&#x2003;(I),where Nt represents the total number of the dimplesand Nu represents the number of the dimpleson one unit.

Golf ball

A golf ball has a large number of dimples on a surface thereof. The golf ball meets the following mathematical formula (I):&#x2266;9.0*&#x2212;6.04&#x2003;&#x2003;(I),Where: So represents a ratio of a sum of spherical surface areas of all the dimples to a surface area of a phantom sphere of the golf ball; and Su represents a standard deviation (mm) of the spherical surface areas of all the dimples. Preferably, the ratio So is equal to or greater than 0.780. Preferably, the standard deviation Su is equal to or less than 2.150 mm. Preferably, a number of the dimples is equal to or greater than 300 but equal to or less than 390. Preferably, an average Sa of the spherical surface areas s of all the dimples is equal to or greater than 14.00 mm.

A golf ballhas a large number of dimpleson a surface thereof. A trajectory of the golf ballis divided into first to fourth segments. An average CD1 of drag coefficients CD and an average CL1 of lift coefficients CL in the first segment are equal to or less than 0.225 and 0.180, respectively. An average CD2 of drag coefficients CD and an average CL2 of lift coefficients CL in the second segment are equal to or less than 0.250 and 0.220, respectively. An average CD3 of drag coefficients CD and an average CL3 of lift coefficients CL in the third segment are equal to or greater than 0.260 and 0.220, respectively. An average CD4 of drag coefficients CD and an average CL4 of lift coefficients CL in the fourth segment are equal to or greater than 0.250 and 0.200, respectively.

A golf ball has a large number of dimples on a surface thereof. The golf ball meets the following mathematical formula (I): 1.320&#x2266;L&#x2266;1.420 (I), where Lrepresents a ratio of a lift coefficient CLwhich is measured under conditions of a Reynolds number of 1.290&#xd7;10and a spin rate of 2820 rpm, relative to a lift coefficient CLwhich is measured under conditions of a Reynolds number of 1.290&#xd7;10and a spin rate of 1740 rpm.

A golf ballhas, on a surface thereof, a rugged pattern consisting of a landand a large number of dimples. A method for designing the rugged pattern includes the steps of:

A golf ballhas, on a surface thereof, a rugged pattern composed of a landand a large number of dimples. A process for designing the rugged pattern includes the steps of:

A golf ball has, on a surface thereof, a rugged pattern composed of a land and a large number of dimples. A method for designing the rugged pattern includes the steps of:

A golf ballhas a large number of dimpleson a surface thereof. A trajectory of the golf ballis divided into first to fourth segments. An average CDof drag coefficients CD and an average CLof lift coefficients CL in the first segment are equal to or less than 0.225 and 0.180, respectively. An average CDof drag coefficients CD and an average CLof lift coefficients CL in the second segment are equal to or less than 0.250 and 0.220, respectively. An average CDof drag coefficients CD and an average CLof lift coefficients CL in the third segment are equal to or greater than 0.260 and 0.220, respectively. An average CDof drag coefficients CD and an average CLof lift coefficients CL in the fourth segment are equal to or greater than 0.250 and 0.200, respectively.

A golf ballhas, on a surface thereof, a dimple pattern consisting of a landand a large number of dimples. A process for designing the dimple pattern includes the steps of:

Process for designing dimple pattern of golf ball

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:

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.

A golf ballincludes a spherical coreand a coverpositioned outside the core. The golf ballfurther has dimpleson a surface thereof. The coreis obtained by crosslinking a rubber composition. The difference between a hardness H(5.0) at a point that is located at a distance of 5 mm from the central point of the core, and a hardness Ho at the central point is equal to or greater than 6.0. The difference between a hardness H(12.5) at a point that is located at a distance of 12.5 mm from the central point, and the hardness H(5.0) is equal to or less than 4.0. The difference between a hardness Hs at the surface of the coreand the hardness H(12.5) is equal to or greater than 10.0. The difference between the hardness Hs and the hardness Ho is equal to or greater than 22.0. There is no zone in which a hardness decreases from the central point to the surface. The rubber composition of the coreincludes 2-naphthalenethiol. A cross-sectional shape of each dimpleis a wave-like curve.

A cross-sectional shape of each of dimplesof a golf ballis a wave-like curve. The wave-like curve has two first curves, two second curves, two third curves, and one fourth curve. Each first curveand each third curveare upwardly convex. Each second curveand the fourth curveare downwardly convex. Each first curveis connoted to a landat an edge Ed. Each second curveis connected to the first curveat a first inflexion point. Each third curveis connected to the second curveat a second inflexion point. The fourth curveis connected to the third curvesat third inflexion points. In the wave-like curve, the upwardly convex curvesandand the downwardly convex curvesandare alternately arranged.

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Kobe, Japan

Hyoungchol Kim