A cross-sectional shape of each of dimples 8 of a golf ball is a wave-like curve. The wave-like curve has two first projections 16 , two second projections 18 , two first recesses 20 , and two second recesses 22 . A circular arc 14 passes through one edge Ed, a deepest point Pd, and another edge Ed. Each first projection 16 is located above the circular arc 14 . Each second projection 18 is located above the circular arc 14 . Each first recess 20 is located below the circular arc 14 . Each second recess 22 is located below the circular arc 14 . The ratio of the distance Lp from an edge Ed to a peak Pp to the radius (Di/2) of the dimple 8 is equal to or greater than 20% but equal to or less than 70%.
1. A golf ball having a large number of dimples on a surface thereof, wherein
at least some dimples have a curved surface,
the cross-sectional shape of the curved surface is a wave-like curve having:
(1) one or more projections located above a circular arc which passes through one dimple edge, a deepest point of the dimple, and another dimple edge; and
(2) one or more recesses located below the circular arc, and the ratio of a distance between a peak of a projection closest to a dimple edge and the dimple edge, to the radius of the dimple, is equal to or greater than 20% but equal to or less than 70%.
2. The golf ball according to claim 1 , wherein one recess is present between the projection closest to the dimple edge and the dimple edge.
3. The golf ball according to claim 1 , wherein the wave-like curve is obtained by combining a sine curve and a circular arc.
4. The golf ball according to claim 3 , wherein the wave-like curve includes cycles with wave amplitudes, each complete cycle corresponds to a segment of the wave-like curve having two consecutive endpoints located at the same amplitude, and the number of cycles of the wave-like curve is equal to or greater than 2.0 but equal to or less than 6.0.
5. The golf ball according to claim 3 , wherein the ratio of an amplitude of the sine curve to a depth of the circular arc is equal to or greater than 5% but equal to or less than 50%.
6. The golf ball according to claim 3 , wherein the ratio of a wavelength of the sine curve to the length of a chord of the circular arc is equal to or greater than 1/6 but equal to or less than 1/2.
7. The golf ball according to claim 3 , wherein the depth of the circular arc is equal to or greater than 0.05 mm but equal to or less than 0.60 mm.
8. The golf ball according to claim 1 , wherein the wave-like curve is obtained by combining a cosine curve and a circular arc.
9. The golf ball according to claim 8 , wherein the wave-like curve includes cycles with wave amplitudes, each complete cycle corresponds to a segment of the wave-like curve having two consecutive endpoints located at the same amplitude, and the number of cycles of the wave-like curve is equal to or greater than 2.5 but equal to or less than 7.0.
10. The golf ball according to claim 8 , wherein the ratio of the amplitude of the cosine curve to the depth of the circular arc is equal to or greater than 5% but equal to or less than 50%.
11. The golf ball according to claim 8 , wherein the ratio of the wavelength of the cosine curve to the length of a chord of the circular arc is equal to or greater than 1/7 but equal to or less than 1/2.5.
12. The golf ball according to claim 8 , wherein the depth of the circular arc is equal to or greater than 0.05 mm but equal to or less than 0.60 mm.
13. The golf ball according to claim 1 , wherein the wave-like curve has 3 to 7 projections.
14. The golf ball according to claim 1 , wherein the diameter of each dimple is equal to or greater than 2.0 mm but equal to or less than 6.0 mm.
15. The golf ball according to claim 1 , wherein the ratio of the number of dimples having a curved surface with a cross-sectional shape that is a wave-like curve, to the total number of the dimples, is equal to or greater than 0.3 but equal to or less than 1.0.
16. The golf ball according to claim 1 , wherein the ratio of the sum of areas of all the dimples to the surface area of a phantom sphere is equal to or greater than 70% but equal to or less than 90%.
17. The golf ball according to claim 1 , wherein the total volume of the dimples is equal to or greater than 250 mm 3 but equal to or less than 400 mm 3 .