| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide different hitting feels to a player in accordance with directions of external force applied to a golf ball at the time of hitting in a golf ball comprising at least a pair of coaxial solid layers in which rigidities of the coaxial solid layers are different from each other. SOLUTION: At boundary surfaces of coaxial solid layers, protruded parts are formed in the surface of a coaxial solid layer of a higher rigidity along the normal direction, recessed parts are formed in the surface of the coaxial solid layer of a low rigidity to correspond to the protruded parts, and both coaxial solid layers are jointed with each other as the protruded parts are engaged in the recessed parts. In a golf ball having a solid core 8 of a two-layer structure comprising a low rigidity inner core 4 (low rigidity coaxial solid layer) and a high rigidity outer core 6 (high rigidity coaxial solid layer), for example, protruded parts 12 are formed in an inner surface of the high rigidity outer core 6 along the normal X direction, recessed parts 14 are formed in an outer surface of the low rigidity inner core 4 to correspond to the protruded parts 12, and the cores 4, 6 are jointed with each other as the protruded parts 12 are engaged with the recessed parts 14.</p> |
