Golf Ball Layer Hardness and Dimples for Flight Consistency

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Solution Overview

Problem

Existing golf balls exhibit significant differences in flight distance when hit at high and low head speeds, leading to inconsistent performance among golfers with varying swing speeds.

Innovation Solution

A golf ball design comprising a spherical core, an intermediate layer, and an outermost cover with specific hardness and thickness parameters, along with a plurality of dimples, to minimize the difference in flight distance between high and low head speed shots.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If the golf ball is designed for high head speed performance, then flight distance at high speed is improved, but flight distance consistency at low speed deteriorates

Engineering Contradiction:
Improvehead speedVSAvoidflight distance consistency
Core Design Contradiction:
SpeedVSReliability

Solution Approach 1:

The patent applies local quality by creating a gradient structure in the core rubber composition, where the crosslinking density varies from the center to the surface. Specifically, the surface crosslinking density is designed to be higher than the center crosslinking density, creating different mechanical properties in different regions of the core. This allows the core to provide appropriate response at both high and low head speeds, resolving the contradiction between high-speed performance and consistency.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the crosslinking density parameter of the core rubber composition to resolve the contradiction. By controlling the crosslinking density to vary spatially (higher at surface, lower at center) and by adjusting the difference parameter (surface crosslinking density - center crosslinking density) to be within -0.05×10² to 0.05×10², the golf ball achieves consistent flight distance across different head speeds while maintaining high-speed performance.

Inventive Principle:
Principle #35Parameter changes

2Strength

If the core crosslinking density is increased to improve compression, then compression performance is improved, but responsiveness to head speed variations deteriorates

Engineering Contradiction:
Improvecompression performanceVSAvoidresponsiveness to head speed
Core Design Contradiction:
StrengthVSAdaptability or versatility

Solution Approach 1:

The patent applies local quality by creating a gradient structure in the core rubber composition, where the crosslinking density varies from the center to the surface. Specifically, the surface crosslinking density is designed to be higher than the center crosslinking density, creating different mechanical properties in different regions of the core. This allows the core to provide appropriate response at both high and low head speeds, resolving the contradiction between high-speed performance and consistency.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes the crosslinking density parameter of the core rubber composition to resolve the contradiction. By controlling the crosslinking density to vary spatially (higher at surface, lower at center) and by adjusting the difference parameter (surface crosslinking density - center crosslinking density) to be within -0.05×10² to 0.05×10², the golf ball achieves consistent flight distance across different head speeds while maintaining high-speed performance.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4470634B1Golf ball
Publication Date: 2025.10.15 SUMITOMO RUBBER INDUSTRIES LTD
  • EP4470634B1 patent drawingFigure 1
  • EP4470634B1 patent drawingFigure 2
  • EP4470634B1 patent drawingFigure 3

AI summary

An object of the present disclosure is to provide a golf ball having a small difference in the flight distance on a driver shot when hit at a high head speed and when hit at a low head speed. The present disclosure provides a golf ball comprising a spherical core, an intermediate layer and an outermost cover, wherein when a center hardness Ho (Shore C hardness) of the spherical core, a surface hardness Hs (Shore C hardness) of the spherical core, a hardness difference S=Hs-Ho, a material hardness Hm (Shore D hardness) of the intermediate layer, a material hardness He (Shore D hardness) of the outermost cover, a thickness Tc (mm) of the outermost cover, and a total lower volume Vi (mm3) of a plurality of dimples satisfy Vi>365 and (Hc/Tc)×(SxHm/Vi)≤130.