| 摘要 |
A mold for a golf ball includes an upper portion ( 1 ) and a lower portion ( 3 ). A large number of projections ( 7 ) for dimple formation are provided on a cavity surface ( 5 ) of each of the upper portion ( 1 ) and the lower portion ( 3 ). A parting surface ( 8 ) of the upper portion ( 1 ) and the lower portion ( 3 ) has a concavo-convex shape. The parting surface ( 8 ) includes a first horizontal plane ( 13 ), a second horizontal plane ( 15 ) and an inclined surface ( 17 ). Circumferential central angles phi of the first horizontal plane ( 13 ) and the second horizontal plane ( 15 ) are 55 degrees or less. A total value Sigmaphi of the circumferential central angles phi is 30 degrees to 330 degrees. An inclination angle alpha of the inclined surface ( 17 ) to a horizontal direction is 10 degrees to 60 degrees. A central angle theta between the horizontal planes ( 13 ) and ( 15 ) and an equator (E) is 1 degree to 8 degrees. A boundary corner portion of the horizontal planes ( 13 ) and ( 15 ) and the inclined surface ( 17 ) is subjected to rounding.
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