Multi-piece Golf Ball Core Hardness Profile Optimization
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Solution Overview
Problem
Existing golf balls with two-layer cores lack optimized hardness profiles and core diameters, resulting in suboptimal distance and controllability, particularly for professional and skilled golfers.
Innovation Solution
A multi-piece solid golf ball with a two-layer core, an intermediate layer, and a cover, where the inner core layer and outer core layer are made of base rubber, the intermediate layer and cover are made of resin materials, and the hardness profile is optimized to achieve higher initial velocity and lower spin rates, with specific gravity differences between core layers and a urethane cover for enhanced controllability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a two-layer core is used in golf balls, then the core structure becomes more complex allowing for differentiated hardness zones, but the hardness profile remains unoptimized resulting in suboptimal distance and controllability
Solution Approach 1:
The patent applies local quality by creating distinct hardness zones within the core structure. The inner core layer has a first hardness value while the outer core layer has a second hardness value that is different from the first. This localized differentiation of material properties optimizes both distance (through softer inner layer) and controllability (through harder outer layer) simultaneously.
Solution Approach 2:
The patent implements parameter changes by specifically controlling the hardness values of the inner and outer core layers. The inner core layer maintains a hardness of 50-70 on the JIS-C scale while the outer core layer has a hardness of 70-95 on the JIS-C scale. These parameter specifications transform the unoptimized two-layer core into a performance-optimized structure.
2Volume of moving object
If the inner core layer diameter is reduced, then the core becomes more compact, but the inner core layer diameter becomes too small reducing flight performance
Solution Approach 1:
The patent applies parameter changes by specifying the inner core layer diameter within the range of 21-30 mm. This parameter optimization ensures the inner core layer is large enough to maintain flight performance and initial velocity while allowing the overall core to remain compact through the harder outer layer design.
3Ease of operation
If the cover is made softer for better feel, then controllability improves, but distance on full shots decreases
Solution Approach 1:
The patent applies segmentation by dividing the core into two distinct layers with different hardness values. The softer inner core layer (JIS-C 50-70) contributes to controllability and feel, while the harder outer core layer (JIS-C 70-95) provides the necessary rigidity for distance on full shots. This segmentation resolves the contradiction between softness for controllability and hardness for distance.
4Ease of operation
If the outer core layer hardness is increased, then controllability improves, but the hardness profile becomes unoptimized reducing overall performance
Solution Approach 1:
The patent applies local quality by positioning the harder material (outer core layer with JIS-C 70-95 hardness) specifically in the region that contacts the intermediate layer and cover. This localized hardness optimization improves controllability without compromising overall performance, as the softer inner core layer maintains energy efficiency and distance.
Data Source
AI summary
In a golf ball having a two-layer core consisting of an inner core layer and an outer core layer, an intermediate layer and a cover, the core is formed primarily of a base rubber, the diameter of the inner core layer is at least 21 mm, the intermediate layer and cover are each formed primarily of a resin material, the overall core has a specific hardness profile, the inner core layer has a higher specific gravity than the outer core layer, and the sphere consisting of the core encased by the intermediate layer has a higher surface hardness than the ball. This golf ball has a high initial velocity at impact while holding down the spin rate on full shots with a driver or long iron, enabling a good distance to be achieved. The ball also has a good controllability in the short game.