Multi-piece solid golf ball

Abstract

The invention provides a multi-piece solid golf ball having a solid core, an inner cover layer and an outer cover layer, which outer cover layer has numerous dimples on a surface thereof. The ball is characterized both in that the core and the inner cover layer are formed so as to have a specific deflection ratio therebetween, and also by the combination of an inner cover layer formed to a specific material hardness and thickness, an outer cover layer formed to a specific material hardness, and dimples which satisfy specific conditions. This multi-piece solid golf ball is able to substantially reduce the distance traveled by the ball when struck at a high head speed, while at the same time holding down the decrease in distance when struck at a low head speed.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application is a continuation-in-part of copending application Ser. No. 12 / 757,829 filed on Apr. 9, 2010, the entire contents of which are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]The present invention relates to a multi-piece solid golf ball having a solid core, an inner cover layer and an outer cover layer, and having numerous dimples on a surface of the outer cover layer. More specifically, the invention relates to a multi-piece solid golf ball which substantially reduces the distance traveled by the ball when struck at a high head speed (head speed is sometimes abbreviated below as “HS”) while at the same time undergoing little reduction in distance when struck at a low HS.[0003]With recent advances in golfing equipment such as balls and clubs, golf balls have come to travel increasing distances. For this reason, to keep play fair, strict rules have been adopted which establish, in the case of a golf club,...

AI Technical Summary

Benefits of technology

[0009]The inventors have conducted extensive investigations in order to achieve the above object. As a result, they have found that, in a multi-piece solid golf ball composed of a solid core, an inner cover layer and an outer cover layer, which outer cover layer has numerous dimples on a surface thereof, by forming the core and the inner cover layer so as to have a specific deflection ratio therebetween; by specifying the thickness and material hardness (Shore D) of the inner cover layer, the material hardness (Shore D) of the outer cover layer, and also the size relationship between the material hardness of the inner cover layer and the material hardness of the outer cover layer; by specifying, for the dimples formed on the surface of the outer cover layer, the number of dimples, the dimple surface coverage (SR), the dimple volume ratio (VR), the dimple types, the average dimple depth, and the dimple diameter-to-depth ratio (DM / DP); and by maintaining the coefficient of lift CL at a Reynolds number of 70,000 and a spin rate of 2,000 rpm at a given ratio or more of the coefficient of lift CL at a Reynolds number of 80,000 and a spin rate of 2,000 rpm, synergistic effects arising from dimple optimization and the suitable hardness relationship between the inner cover layer and the outer cover layer make it possible to substantially reduce the distance traveled by the ball when struck at a high HS while at the same time holding down the decrease in distance when the ball is struck at a low HS.

[0010]That is, unlike conventional methods of lowering the ball initial velocity or core initial velocity, the golf ball of the present invention is able, by combining low-trajectory dimples with the internal structure (multilayer structure) of the ball, to substantially reduce the distance traveled by the ball when struck at a high HS while at the same time holding down to the extent possible, relative to the reduction in distance on high HS shots, the reduction in the distance traveled by the ball on low HS shots. As used herein, “distance” refers to the total distance traveled by a golf ball, including both the carry and the run.

Problems solved by technology

As a result, such balls have significant drawbacks for low HS players.

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