Golf Ball Core Deflection and Hardness Gradient for Soft Feel
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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 and consistently delivering either satisfactory flight or softness.
Innovation Solution
A golf ball design with a core and cover that satisfies specific deflection and hardness ratios, utilizing a rubber core with zinc acrylate as a co-crosslinking agent and a Shore D hardness cover, ensuring a soft feel, high initial velocity, and durability through precise core and cover layer construction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the core is made soft to provide a soft feel for senior and women golfers, then the feel at impact is improved, but the flight performance deteriorates
Solution Approach 1:
The patent applies local quality by creating a core with a specific hardness profile that varies with depth - softer at the center for feel and harder at the periphery for energy transfer. The core has a hardness of 50-60 at the center and 65-75 at the periphery, allowing different regions to serve different functions
Solution Approach 2:
The patent changes physical parameters by specifying precise deflection values (E≥4.0mm, E/B≥1.05) and hardness values at different core positions. These parameter changes enable the core to be soft enough for feel while maintaining structural integrity for flight performance
2Ease of operation
If the core deflection is increased to improve soft feel, then the softness is improved, but the durability to cracking deteriorates
Solution Approach 1:
The patent uses local quality by making the core periphery harder (65-75 JIS-C hardness) than the center (50-60 JIS-C hardness). This gradient structure allows the core to deflect sufficiently for soft feel while the harder periphery resists cracking and maintains durability
Solution Approach 2:
The patent employs composite material principles by combining rubber materials with specific physical properties - the core has a deflection E of 4.0mm or more and specific gravity of 0.92-0.96, creating a composite structure that balances softness and durability
3Speed
If the core is made hard to improve flight performance, then the initial velocity is improved, but the soft feel deteriorates
Solution Approach 1:
The patent applies local quality by creating a core with softer center (50-60 JIS-C hardness) and harder periphery (65-75 JIS-C hardness). The softer center provides good feel at impact while the overall core structure maintains sufficient initial velocity
Solution Approach 2:
The patent changes parameters by specifying the core deflection E must be 4.0mm or more and the ratio E/B must be 1.05 or more. These parameter changes ensure the core is soft enough for feel while maintaining flight performance
4Reliability
If the cover thickness is increased to improve durability, then the durability to cracking is improved, but the soft feel deteriorates
Solution Approach 1:
The patent changes parameters by specifying the cover thickness T must be in the range of 0.8-1.6mm and the ratio D/T must be 25-32. These parameter changes optimize the balance between durability and soft feel
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 achieves a soft feel, excellent flight performance, and sufficient durability to cracking, meeting the needs of amateur golfers with lower head speeds by optimizing core and cover layer properties.
Implementation Method 1
the core and the golf ball have respective deflections E (mm) and B (mm) when compressed under a final load of 1,275 N (130 kgf) from an initial load state of 98 N (10 kgf)
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 E (mm) and B (mm), the following conditions are satisfied: (1) 30≥D/T≥24, (2) 4.1≥E/T≥2.6, and (3) 1.18≥EIB≥1.09, and the core has specific hardness profile. 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.