Golf Ball Core Cover Design for Soft Feel and Durability
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Solution Overview
Problem
Golf balls designed for senior and women golfers with lower head speeds often compromise between flight performance and soft feel, lacking durability against cracking.
Innovation Solution
A golf ball design with a core and cover that satisfies specific deflection and hardness ratios, combined with strategic support pin placement in the molding process, to achieve a soft feel, high initial velocity, and improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the core is made soft to provide a soft feel at impact, then the durability to cracking deteriorates
Solution Approach 1:
The core is designed with non-uniform hardness distribution, where the outer layer has higher hardness (65-75 JIS-C) to resist cracking and the inner layer has lower hardness (55-65 JIS-C) to provide soft feel at impact. This local quality differentiation allows simultaneous achievement of soft feel and durability.
Solution Approach 2:
The core is constructed as a composite structure with at least two layers of different materials or compositions. The outer layer uses harder material for crack resistance, while the inner layer uses softer material for impact absorption and soft feel, creating a composite that balances both requirements.
2Speed
If the core deflection is increased to improve initial velocity and flight performance, then the soft feel at impact deteriorates
Solution Approach 1:
The core's non-uniform hardness distribution allows different regions to serve different functions: the inner soft region provides impact absorption for soft feel, while the outer harder region maintains structural integrity and contributes to initial velocity through controlled deformation during impact.
Solution Approach 2:
The core deflection is precisely controlled within the range of 4.0-5.0 mm under a final load of 1,275 N, and the hardness profile is optimized with specific JIS-C hardness values at different depths. These parameter optimizations balance initial velocity generation with soft feel maintenance.
3Reliability
If the cover thickness is increased to improve durability, then the initial velocity and flight performance deteriorate
Solution Approach 1:
The cover thickness is precisely controlled within the range of 1.0-1.5 mm, and the core diameter to cover thickness ratio (D/T) is maintained between 24-30. These parameter optimizations ensure sufficient durability while preserving initial velocity and flight performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The golf ball provides a soft feel, excellent flight performance, and enhanced durability against cracking, meeting the needs of amateur golfers with lower head speeds.
Implementation Method 1
the support pins can be held in place until just before spreading of the molten resin within the mold cavity during injection molding of the cover material is complete
Implementation Method 2
arranging the support pins used in the golf ball mold so as to be positioned at places within an angle of 21° to a center axis perpendicular to the mold parting line
Implementation Method 3
spreading of the molten resin within the mold cavity during injection molding of the cover material
Data Source
AI summary
In a golf ball having a core and a cover of one or more layers, letting the core diameter be D (mm), the cover thickness be T (mm) and the core and ball deflections when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf) be 5 (mm) and B (mm), the following conditions are satisfied: (1) 30≥D/T≥24, (2) 3.9≥E/T≥3.0, and (3) 1.18≥E/B≥1.09. This golf ball provides an excellent flight performance and a soft feel at impact when used by golfers whose head speed is not very fast, such as senior golfers and women golfers. The ball also has a high durability to cracking on repeated impact.