Golf Ball Hardness Gradient for Spin Suppression
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Solution Overview
Problem
Conventional golf balls with an outer-hard/inner-soft structure have an inadequate continuity of hardness distribution, leading to insufficient suppression of spin and subpar flight performance, particularly when hit with drivers.
Innovation Solution
A golf ball design featuring a center with a diameter of 1 mm to 15 mm and a mid layer with a significant hardness difference between the surface and innermost parts, achieving an outer-hard/inner-soft structure with improved continuity of hardness distribution, utilizing crosslinked rubber compositions with polybutadiene as the principal component and specific vulcanization accelerators and fillers to enhance resilience and spin suppression.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a conventional outer-hard/inner-soft structure is used with a soft center and hard mid layer, then the golf ball achieves some spin suppression, but the level difference in hardness on the boundary deteriorates spin suppression and reduces flight performance
Solution Approach 1:
The center is divided into multiple layers with progressively varying hardness from the core outward, creating a gradient structure that eliminates abrupt transitions. This segmentation allows each sub-layer to contribute to smooth hardness distribution while collectively achieving superior spin suppression and flight performance.
Solution Approach 2:
Different regions of the center are assigned different hardness characteristics - the core remains soft for feel and energy storage, while intermediate layers progressively increase in hardness to ensure continuity. This local differentiation resolves the contradiction by optimizing each region's properties for its specific function while maintaining overall compositional stability.
2Object-generated harmful factors
If the center diameter is reduced to enhance the outer-hard/inner-soft structure, then spin suppression improves, but the hardness distribution continuity may be compromised
Solution Approach 1:
The center is segmented into multiple concentric layers with progressively varying hardness, allowing the overall small diameter to accommodate fine-grained hardness transitions. This segmentation enables continuous hardness distribution even within a compact diameter, simultaneously achieving spin suppression and compositional stability.
Solution Approach 2:
Instead of varying hardness only radially across a large diameter, the invention introduces dimensional complexity by creating multiple concentric layers with progressive hardness gradients. This transforms the one-dimensional hardness variation into a multi-layered structure, achieving continuity within a smaller diameter space.
3Object-generated harmful factors
If the hardness difference in the mid layer is increased to achieve outer-hard/inner-soft structure, then spin suppression is enhanced, but the boundary level difference deteriorates flight performance
Solution Approach 1:
The mid layer is segmented into multiple sub-layers with progressive hardness transitions, reducing the abruptness of the boundary level difference. This segmentation allows the overall hardness difference to remain large for spin suppression while the incremental transitions within each sub-layer maintain manufacturing precision and flight performance.
Solution Approach 2:
The invention applies parameter changes by progressively varying the hardness parameter across multiple layers rather than using a single abrupt transition. This gradual parameter change maintains the overall hardness difference needed for spin suppression while avoiding the harmful boundary level differences that degrade 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 achieves excellent flight performance with reduced spin and enhanced resilience, meeting the demand for increased flight distance and improved feel at impact, as demonstrated by the results of ball speed and spin rate measurements.
Implementation Method 1
The center has a central point having a JIS-C hardness H1 of 20 or greater and 50 or less... crosslinked rubber compositions with polybutadiene as the principal component... to enhance resilience
Data Source
AI summary
A golf ball 2 has a spherical core 4 and a cover 6 positioned outside this core 4. The core 4 has a spherical center 8 and a mid layer 10 positioned outside this center 8. The center 8 is formed by crosslinking a rubber composition. A base rubber of the rubber composition contains polybutadiene as a principal component. The rubber composition contains sulfur as a crosslinking agent. The center 8 has a diameter of 1 mm or greater and 15 mm or less. The center 8 has a central hardness H1 of 20 or greater and 50 or less. A difference (H4−H3) between a hardness H4 of a surface of the mid layer 10 and a hardness of an innermost part thereof is equal to or greater than 10.