GOLF BALL
A golf ball 2 includes an inner core 4 , an outer core 6 , a mid layer 8 , a cover 10 , and dimples 12 . A diameter D1, a volume V1, a hardness H1o at a central point, a boundary inside hardness H1in, and a hardness difference De1 of the inner core 4 ; a volume V2 (mm 3 ) and a hardness difference De2 of the outer core 6 ; a thickness Tm and a hardness Hm of the mid layer 8 ; and a thickness Tc and a hardness Hc of the cover 10 meet the following mathematical formulas. 1.0< V 2/ V 1<7.0 De 2− De 1<0 600<( H 1 o*H 1 in )*( D 1/2)/2<1000 620< Tc*Hc*Hm/Tm <900 The dimples 12 include a plurality of small dimples each having an area of less than 8.0 mm 2 .
1 . A golf ball comprising an inner core, an outer core positioned outside the inner core, a mid layer positioned outside the outer core, and a cover positioned outside the mid layer, wherein
the golf ball has a plurality of dimples on a surface thereof,
the dimples include a plurality of small dimples each having an area of less than 8.0 mm 2 and a plurality of large dimples each having an area of equal to or greater than 8.0 mm 2 ,
a ratio PS of a sum of the areas of the small dimples relative to a surface area of a phantom sphere of the golf ball is less than 2.0%,
a ratio PL of a sum of the areas of the large dimples relative to the surface area of the phantom sphere is equal to or greater than 79.0%, and
a degree of uniformity G of the areas (mm 2 ) of the large dimples is equal to or less than 1.15.
2 . The golf ball according to claim 1 , wherein
a volume V1 (mm 3 ) of the inner core and a volume V2 (mm 3 ) of the outer core meets the following mathematical formula (1),
1.0< V 2/ V 1<7.0 (1).
3 . The golf ball according to claim 2 , wherein the golf ball meets the following mathematical formula:
2.0< V 2/ V 1<6.0.
4 . The golf ball according to claim 1 , wherein
a difference De1 between a boundary inside hardness H1in (Shore C) and a hardness H1o (Shore C) at a central point of the inner core; and a difference De2 between a surface hardness H2s (Shore C) and a boundary outside hardness H2out (Shore C) of the outer core meets the following mathematical formula (2),
De 2− De 1<0 (2).
5 . The golf ball according to claim 1 , wherein
a diameter D1 (mm), a hardness H1o (Shore C) at a central point, and a boundary inside hardness H1in (Shore C) meets the following mathematical formula (3),
600<( H 1 o+H 1 in )*( D 1/2)/2<1000 (3).
6 . The golf ball according to claim 5 , wherein the golf ball meets the following mathematical formula:
700<( H 1 o+H 1 in )*( D 1/2)/2<900.
7 . The golf ball according to claim 1 , wherein
a thickness Tm (mm) and a hardness Hm (Shore D) of the mid layer; and a thickness Tc (mm) and a hardness Hc (Shore D) of the cover meets the following mathematical formula (4),
620< Tc*Hc*Hm/Tm< 900 (4).
8 . The golf ball according to claim 7 , wherein the golf ball meets the following mathematical formula:
640< Tc*Hc*Hm/Tm< 800.
9 . The golf ball according to claim 1 , wherein the ratio PS is equal to or greater than 0.7%.
10 . The golf ball according to claim 1 , wherein a number NS of the small dimples is equal to or greater than 6 but equal to or less than 20.
11 . The golf ball according to claim 1 , wherein a ratio (NS/N) of a number NS of the small dimples relative to a total number N of the dimples is equal to or greater than 0.01 but equal to or less than 0.07.
12 . The golf ball according to claim 1 , wherein a depth of a deepest part of each dimple from a surface of the phantom sphere is equal to or greater than 0.10 mm but equal to or less than 0.65 mm.
13 . The golf ball according to claim 1 , wherein a total volume of the dimples is equal to or greater than 450 mm 3 but equal to or less than 750 mm 3 .
14 . The golf ball according to claim 1 , wherein the ratio PL is equal to or greater than 79.5%, and the degree of uniformity G is equal to or less than 1.10.
15 . The golf ball according to claim 14 , wherein the ratio PL is equal to or greater than 80.0%, and the degree of uniformity G is equal to or less than 1.05.