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 maintained at various distances from the center, satisfying the relations (H2.5-H0)>(H12.5-H10)>(Hs-H15), enhancing initial velocity and spin rates.
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 is designed with non-uniform hardness distribution where the center hardness (Cc) and surface hardness (Cs) differ significantly. Specifically, the hardness gradient is controlled such that Cc ≤ 70 and Cs-Cc ≥ 10, with additional constraints on hardness at intermediate positions (C5-Cc ≥ 0, Cm-Cc ≥ 2). This local variation in hardness allows the core to provide different mechanical responses at different locations during impact, enabling low spin on driver shots while maintaining high spin on approach shots.
Solution Approach 2:
The patent applies parameter changes by precisely controlling multiple hardness parameters simultaneously: center hardness (Cc), surface hardness (Cs), hardness at 5mm from center (C5), and hardness at midpoint (Cm). The relationships between these parameters are optimized to achieve the dual goal of distance and spin control. By adjusting these hardness parameters within specific ranges and relationships, the golf ball delivers improved flight distance on driver shots while maintaining excellent spin performance on approach shots.
2Speed
If the core hardness difference between surface and center is increased to improve flight distance, then flight distance is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent defines specific parameter ranges and relationships for core hardness: Cc ≤ 70, Cs-Cc ≥ 10, C5-Cc ≥ 0, and Cm-Cc ≥ 2. These quantified parameters provide clear manufacturing targets and acceptance criteria, enabling precise control of hardness distribution during production. The use of Shore C hardness measurements at standardized positions allows for consistent quality control.
Solution Approach 2:
Instead of attempting to create a uniform hard core and then softening specific regions, the patent inverts the approach by designing the core with inherently different hardness at the center versus the surface from the outset. This is achieved by controlling the rubber composition and curing process to naturally produce the desired hardness gradient, simplifying manufacturing compared to post-processing approaches.
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-H0)>(H12.5-H10)>(HS-H15).