In a golf ball having a core, an intermediate layer and a cover, the intermediate layer-encased sphere has a higher surface hardness than the ball. The core hardness profile in the ball is designed such that the core surface has a Shore C hardness value which is at least 27 higher than the Shore C hardness value at the core center, and the surface areas A to F calculated from hardness differences between positions located at specific distances in the core and differences between the specific distances satisfy a specific formula. This golf ball has an excellent flight performance when struck by skilled amateur golfers and professionals, and also has a good controllability on shots with an iron.

The present invention is directed to golf balls having improved aerodynamic performance due, at least in part, to the selection of the plan shapes of the dimples thereon. In particular, the present invention is directed to a golf ball that includes at least a portion of its dimples having a plan shape defined by a periodic cosine function mapped along a circular closed path. In addition, the present invention provides methods for designing dimples having a plan shape defined by a periodic cosine function mapped along a circular closed path.

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 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.

A golf ball having a core and a cover that is formed of a resin composition which includes (A) a polyurethane or a polyurea and (B) a styrenic resin material, when dropped from a height of 3 m and made to collide with a metal plate, has velocities 200 ms before and 200 ms after contact that satisfy the condition: (incident velocity)(rebound velocity)0.80 m/s. The ball has a good controllability on approach shots without a loss in the distance achieved on shots with a driver, and thus is particularly useful to professional golfers and skilled amateurs.

In a golf ball having a two-layer core consisting of an inner core layer and an outer core layer, an intermediate layer consisting of at least one layer and a cover of one or more layer, the inner core layer and outer core layer are each formed of a rubber composition made up primarily of a base rubber, the inner core layer has a diameter of not more than 30 mm; and the core has specific hardness ratios (JIS-C hardness/Shore D hardness) at specific points on the cross-section thereof and the surface and center of the two-layer core has a specific hardness difference. This golf ball has a reduced spin rate on full shots with a driver and middle irons, thus imparting an excellent flight performance, and moreover has a good controllability in the short game on approach shots, making it ideal as a golf ball for professional golfers and mid- and high-level amateur golfers.

A golf ball has a plurality of minute projections 20 on a surface thereof. An average value Hav of heights H of these minute projections 20 is not less than 0.5 m and not greater than 50 m. The surface of the golf ball has one or more first zones and one or more second zones. An average value Hav1 of the heights H of the minute projections 20 on these first zones is higher than an average value Hav2 of the heights H of the minute projections 20 on these second zones. Preferably, the average value Hav1 and the average value Hav2 satisfy the following mathematical formula.
3(Hav1Hav2)50

The golf ball 1 includes a surface having multiple dimples thereon. When a lift coefficient measured under conditions with a Reynolds number of 80000 and a spin rate of 2000 rpm is CL1, and when a lift coefficient measured under conditions with a Reynolds number of 70000 and a spin rate of 1900 rpm is CL2, CL1 and CL2 satisfy 0.990CL2/CL1.

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.