In a multi-piece solid golf ball having a core, an intermediate layer encasing the core and a cover which encases the intermediate layer and has numerous dimples on an outside surface thereof, the intermediate layer is formed of a resin material, the cover is formed of a urethane resin material, the core has a diameter of at least 38.0 mm, the core has a deflection when compressed under a final load of 1,275 N (130 kgf) from an initial load of 98 N (10 kgf) of at least 3.9 mm, the core has a center and a surface such that the value obtained by subtracting the JIS-C hardness at the core center from the JIS-C hardness at the core surface is at least 15, the sphere obtained by encasing the core with the intermediate layer (intermediate layer-encased sphere) has a surface hardness on the Shore D hardness scale of at least 69, the ball has a surface hardness on the Shore D hardness scale of 62 or less, and the (intermediate layer thickness)/(core diameter) value is from 0.025 to 0.043, the (cover thickness)/(core diameter) value is from 0.014 to 0.027.

Golf balls having outer surfaces with improved dimple patterns are provided. At least a portion of the dimples are spherical, and the spherical dimples have at least two different dimple diameters. Each spherical dimple has a radius of curvature that is substantially equal to the radius of curvature of every other spherical dimple on the outer surface of the ball. In another embodiment, the spherical dimples have at least three different dimple diameters. The spherical dimples having different dimple diameters also can have different edge angles, dimple depths, and/or dimple volumes. In one preferred embodiment, the maximum difference in radius of curvature between any two spherical dimples is less than or equal to 0.015 inches.

Golf balls having a dimple pattern arranged in an icosahedral layout are disclosed. The dimple pattern has 20 substantially identical dimple sections, where each dimple section is defined by a spherical triangle. The dimples in each of the 20 dimple sections have at least three different dimple diameters including a minimum dimple diameter, a maximum dimple diameter, and at least one additional dimple diameter. The resulting dimple pattern has a surface coverage of about 70 percent or less. The reduced surface coverage helps to reduce the flight of the golf balls.

Golf balls having a dimple pattern arranged in a tetrahedral layout are disclosed. The dimple pattern has four substantially identical dimple sections, where each dimple section is defined by a spherical triangle. The dimples in each of the four dimple sections have at least three different dimple diameters including a minimum dimple diameter, a maximum dimple diameter, and at least one additional dimple diameter. The resulting dimple pattern has a surface coverage of about 70 percent or less. The reduced surface coverage helps to reduce the flight of the golf balls.

Golf balls having dimple patterns arranged in dipyramid layouts are disclosed. The patterns may be arranged in triangular dipyramid, quadrilateral dipyramid, pentagonal dipyramid, or hexagonal dipyramid layouts. The dipyramid patterns have six, eight, ten, or twelve substantially identical dimple sections, where each dimple section is defined by a spherical triangle. The dimples in each of the identical dimple sections have at least two different dimple diameters including a minimum dimple diameter and a maximum dimple diameter. The resulting dimple patterns have a surface coverage of about 70 percent or less. The reduced surface coverage helps to reduce the flight of the golf balls.

The present invention provides a method for arranging dimples on a golf ball surface in which the dimples are arranged in a pattern derived from at least one irregular domain generated from a regular or non-regular polyhedron. The method includes choosing control points of a polyhedron, generating an irregular domain based on those control points, packing the irregular domain with dimples, and tessellating the irregular domain to cover the surface of the golf ball. The control points include the center of a polyhedral face, a vertex of the polyhedron, a midpoint or other point on an edge of the polyhedron and others. The method ensures that the symmetry of the underlying polyhedron is preserved while minimizing or eliminating great circles due to parting lines.

The present invention provides a method for arranging dimples on a golf ball surface in which the dimples are arranged in a pattern derived from at least one irregular domain generated from a regular or non-regular polyhedron. The method includes choosing control points of a polyhedron, generating an irregular domain based on those control points, packing the irregular domain with dimples, and tessellating the irregular domain to cover the surface of the golf ball. The control points include the center of a polyhedral face, a vertex of the polyhedron, a midpoint or other point on an edge of the polyhedron and others. The method ensures that the symmetry of the underlying polyhedron is preserved while minimizing or eliminating great circles due to parting lines.

The present invention is directed to a mold for forming the cover of a golf ball having a non-planar parting line on its spherical surface.

A golf ball can have a relatively large number of dimples on a surface thereof. A trajectory of the golf ball calculated under conditions of an initial speed of 260 ft/s, a launch angle of 15.0 degrees, and an initial backspin rate of 3000 rpm can satisfy the following mathematical formula:

Amin≥−5.0*Vave−38.98,

wherein A min represents a minimum value (degree) of a vector angle A in the trajectory, and Vave represents an average volume (mm.sup.3) of the dimples. The vector angle A can be calculated by the following mathematical formula:

A=ATAN(Vy/Vx),

wherein Vx represents a horizontal component of a speed of the golf ball, and Vy represents a vertical component of the speed of the golf ball.

A golf ball can have a large number of dimples on a surface thereof. A trajectory of the golf ball can be calculated under conditions of an initial speed of 260 ft/s, a launch angle of 15.0 degrees, and an initial backspin rate of 3000 rpm satisfying the following mathematical formula,

[00001]$\text{Amax}\ge \text{4}\text{.0}\text{*}\text{Vave + 13}\text{.10,}$

wherein Amax represents a maximum value (degree) of a vector angle A in the trajectory, and Vave represents an average volume (mm.sup.3) of the dimples. The vector angle A can be calculated by the mathematical formula

[00002]$\text{A}\text{=}\text{ATAN}\left(\text{Vy}/\text{Vx}\right),$

wherein Vx represents a horizontal component of a speed of the golf ball, and Vy represents a vertical component of the speed of the golf ball.