Multi-piece Golf Ball Core Hardness Gradient for Distance and Feel
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Solution Overview
Problem
Existing multi-piece solid golf balls fail to achieve a balance between distance and feel on impact, with hard inner core layers resulting in increased spin but reduced distance, and soft core layers leading to low initial velocity.
Innovation Solution
A multi-piece solid golf ball design featuring a thermoplastic resin inner core layer with a specific hardness distribution and a polybutadiene rubber outer core layer, combined with a harder outer cover layer, to enhance rebound and distance while maintaining a good feel on impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If the inner core layer is made hard to increase spin rate, then spin performance is improved, but distance performance deteriorates
Solution Approach 1:
The core is divided into two distinct layers: an inner core layer made of hard thermoplastic resin (Shore D hardness 40-60) to generate high spin rate, and an outer core layer made of soft rubber composition (Shore D hardness 20-40) to provide cushioning and maintain distance performance. This segmentation allows each layer to independently contribute its specific 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 high hardness (Shore D 40-60) optimized for spin generation, while the outer core layer has low hardness (Shore D 20-40) optimized for cushioning and distance. The cover layer also has higher hardness (Shore D 40-70) than the outer core layer to provide durability and control.
2Ease of operation
If the inner core layer is made soft to improve feel on impact, then feel performance is improved, but initial velocity and distance performance deteriorate
Solution Approach 1:
The core is divided into two distinct layers: an inner core layer made of hard thermoplastic resin (Shore D hardness 40-60) to generate high spin rate, and an outer core layer made of soft rubber composition (Shore D hardness 20-40) to provide cushioning and maintain distance performance. This segmentation allows each layer to independently contribute its specific function without compromising the other.
Solution Approach 2:
The golf ball utilizes a composite structure combining thermoplastic resin (inner core) with rubber composition (outer core and cover layers). This composite material approach allows the hard inner core to generate spin while the soft rubber outer layers provide cushioning and distance, achieving both feel and velocity performance simultaneously.
3Length of moving object
If the outer core layer hardness is increased to improve distance performance, then distance is improved, but feel on impact deteriorates
Solution Approach 1:
The core is divided into two distinct layers: an inner core layer made of hard thermoplastic resin (Shore D hardness 40-60) to generate high spin rate, and an outer core layer made of soft rubber composition (Shore D hardness 20-40) to provide cushioning and maintain distance performance. This segmentation allows each layer to independently contribute its specific 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 high hardness (Shore D 40-60) optimized for spin generation, while the outer core layer has low hardness (Shore D 20-40) optimized for cushioning and distance.
4Ease of operation
If the cover layer is made softer to improve feel on impact, then feel performance is improved, but durability and control performance deteriorate
Solution Approach 1:
The cover layer has higher hardness (Shore D 40-70) than the outer core layer (Shore D 20-40), creating a hardness gradient from the center outward. This local quality differentiation allows the soft outer core to provide cushioning for good feel, while the harder cover layer provides durability and control performance.
Data Source
AI summary
A multi-piece solid golf ball composed of a solid core having an inner core layer and an outer core layer encased by a cover including at least an inner cover layer and an outer cover layer. The inner core layer has a JIS-C cross-sectional hardness of from 60 to 83 at any single point on a cross-section, and has a cross-sectional hardness difference between any two points on the cross-section of within ±5. The ball has specific relationships between the hardness of the inner core layer 1 mm inside a boundary between the inner core layer and the outer core layer, the hardness of the outer core layer 1 mm outside the boundary, and the surface hardness of the outer core layer. And, the outer cover layer has the specific thickness and Shore D hardness, which is higher than that of the inner cover layer.