Multi-piece Golf Ball Two-layer Core Design
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Solution Overview
Problem
Mid- to high-level amateur golfers and professionals face challenges in achieving a balance between maximizing distance on full shots and maintaining high spin performance on approach shots with existing multi-piece solid golf balls, as current designs often compromise on either distance or spin due to core hardness and layer thickness profiles.
Innovation Solution
A multi-piece solid golf ball design featuring a rubber two-layer core with a large inner core diameter of at least 30 mm, a specific hardness profile, and an intermediate layer with higher material hardness than the cover, optimized to reduce spin rates on full shots while maintaining high spin performance on approach shots.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the core is made softer to increase distance on full shots, then the initial velocity increases, but the spin rate on approach shots decreases
Solution Approach 1:
The core is divided into two distinct layers: an inner soft layer (JIS-C hardness 40-60) that deforms easily to generate high initial velocity on full shots, and an outer hard layer (JIS-C hardness 70-90) that maintains structural integrity and generates sufficient spin on approach shots. This segmentation allows each layer to perform its specialized function without compromising the other.
Solution Approach 2:
Different regions of the core have different hardness properties tailored to their specific functions. The inner core layer has low hardness optimized for distance on full shots, while the outer core layer has high hardness optimized for spin control on approach shots. This local differentiation of material properties resolves the contradiction between distance and spin performance.
2Object-generated harmful factors
If the core is made harder to maintain spin on approach shots, then the spin rate increases, but the initial velocity on full shots decreases
Solution Approach 1:
The core is divided into two distinct layers: an inner soft layer (JIS-C hardness 40-60) that deforms easily to generate high initial velocity on full shots, and an outer hard layer (JIS-C hardness 70-90) that maintains structural integrity and generates sufficient spin on approach shots. This segmentation allows each layer to perform its specialized function without compromising the other.
Solution Approach 2:
Different regions of the core have different hardness properties tailored to their specific functions. The inner core layer has low hardness optimized for distance on full shots, while the outer core layer has high hardness optimized for spin control on approach shots. This local differentiation of material properties resolves the contradiction between distance and spin performance.
3Object-generated harmful factors
If the inner core layer diameter is increased to reduce spin rate on full shots, then the spin rate decreases, but the ball construction complexity increases
Solution Approach 1:
The core is divided into two distinct layers: an inner soft layer (JIS-C hardness 40-60) that deforms easily to generate high initial velocity on full shots, and an outer hard layer (JIS-C hardness 70-90) that maintains structural integrity and generates sufficient spin on approach shots. This segmentation allows each layer to perform its specialized function without compromising the other.
Solution Approach 2:
The invention specifies precise parameter ranges for the two-layer core structure: inner layer diameter of at least 30 mm, inner layer hardness of JIS-C 40-60, outer layer hardness of JIS-C 70-90, and the hardness difference of at least 25. These controlled parameter changes achieve the desired spin rate reduction while maintaining manufacturability within established industry standards.
Data Source
AI summary
In a multi-piece solid golf ball having a rubber two-layer core consisting of an inner layer and an outer layer, a cover, and at least one intermediate layer therebetween, the inner core layer has a diameter of at least 30 mm, the difference in JIS-C hardness between the center of the inner core layer and the surface of the outer core layer is at least 25, the ball satisfies the relationship A/B≦1.5, where A and B are the deflections of, respectively, the inner core layer and the two-layer core when compressed under specific loading conditions, and the intermediate layer has a higher material hardness than the cover. This ball enables mid- to high-level golfers both to achieve even longer distances and to maintain the spin performance on approach shots at a high level.