Golf Ball Core Hardness Gradient for Distance and Rough Spin
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Solution Overview
Problem
Existing golf balls struggle to balance flight distance on driver shots with spin performance on approach and middle iron shots, particularly when grass is present between the ball and the club face.
Innovation Solution
A golf ball design with a spherical core and cover, where specific hardness gradients are defined as (H2.5−H0)>(H12.5−H10)>(Hs−H15), optimizing initial velocity and spin rates through controlled hardness differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the spin rate on driver shots is lowered to increase flight distance, then flight distance on driver shots is improved, but spin rate on middle iron shots and approach shots decreases
Solution Approach 1:
The core of the golf ball is designed with a non-uniform hardness distribution where the center hardness (Cc) is lower than the surface hardness (Cs), creating different local properties. Specifically, the hardness gradient is controlled such that the difference between center and surface hardness satisfies 15 ≤ Cs-Cc ≤ 25, while the difference between surface hardness and hardness 3mm inside the surface satisfies 0 ≤ Cs-Cs3 ≤ 5. This local quality variation allows the ball to generate appropriate spin on approach shots while maintaining low spin on driver shots for extended flight distance.
Solution Approach 2:
The invention changes the physical parameter of core hardness distribution from uniform to non-uniform. By controlling the hardness values at different radial positions (Cc, Cm, Cs, Cs3) and their relationships, the ball's response to different types of shots is optimized. The parameter Cs-Cc is maintained between 15-25, and Cs-Cs3 between 0-5, creating a specific hardness profile that resolves the contradiction between flight distance and spin performance.
2Object-generated harmful factors
If the core hardness is increased to improve spin performance on approach shots, then spin rate on approach shots is improved, but flight distance on driver shots decreases
Solution Approach 1:
The core hardness is made non-uniform with a specific gradient: the center is softer (Cc) and the surface is harder (Cs), with controlled differences. The hardness 3mm inside the surface (Cs3) is kept very close to surface hardness (Cs-Cs3 ≤ 5), while the center-to-surface difference (Cs-Cc) is maintained between 15-25. This local quality distribution allows the surface to generate spin on approach shots while the softer center maintains elasticity for driver shot distance.
3Object-generated harmful factors
If the hardness difference between core surface and center is increased to improve spin performance, then spin rate on middle iron shots and approach shots is improved, but initial velocity on driver shots decreases
Solution Approach 1:
The invention optimizes the hardness difference parameter Cs-Cc to be between 15-25, which is sufficient to generate spin on middle iron and approach shots but not excessive to harm initial velocity on driver shots. Additionally, the parameter Cs-Cs3 is constrained to 0-5, ensuring the surface region has uniform hardness for consistent spin generation while the overall gradient provides the necessary spin performance without sacrificing driver shot velocity.
Data Source
AI summary
An object of the present disclosure is to provide a golf ball having improved flight distance on driver shots and excellent spin performance on approach shots (particularly under the condition that there is grass between the golf ball and the club face) and on middle iron shots. The present disclosure provides a golf ball comprising a spherical core and a cover disposed outside the spherical core, wherein when a center hardness of the spherical core (Shore C hardness), hardnesses at 2.5 mm, 5 mm, 7.5 mm, 10 mm, 12.5 mm and 15 mm points from a center of the spherical core toward a surface of the spherical core (Shore C hardness), and a surface hardness of the spherical core (Shore C hardness) are represented by H0, H2.5, H5, H7.5, H10, H12.5, H15 and Hs respectively, the following relation is satisfied:(H2.5−H10)>(H12.5−H10)>(Hs−H15).