Multi-piece Golf Ball Core Hardness Design
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Solution Overview
Problem
Existing multi-piece solid golf balls fail to achieve sufficient distance and initial velocity due to hard inner core layers and soft center cores, which affect the ball's rebound and feel upon impact.
Innovation Solution
A multi-piece solid golf ball design featuring an inner core layer made of a thermoplastic resin with specific hardness and size, and an outer core layer of polybutadiene rubber with a high resilience and hardness distribution, combined with a cover layer for optimized deformation and spin performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the inner core layer is made hard to improve rebound and distance, then the spin rate increases and feel becomes hard on full shots
Solution Approach 1:
The core is divided into two distinct layers: an inner core layer made of thermoplastic resin with specific hardness (Shore D 40-60) and an outer core layer made of rubber composition with different hardness (Shore D 30-50). This segmentation allows each layer to perform its specific function - the inner layer provides rebound and initial velocity while the outer layer controls spin and softens the feel on impact.
Solution Approach 2:
Different materials with specific local properties are used in different regions of the core. The inner core layer uses thermoplastic resin with controlled hardness to optimize rebound, while the outer core layer uses rubber composition to reduce spin and improve feel. Each layer's material properties are specifically tailored to its functional requirements rather than using a uniform material throughout.
2Ease of operation
If the center core is made soft to improve feel on impact, then the initial velocity decreases and distance performance is insufficient
Solution Approach 1:
The core is divided into two distinct layers: an inner core layer made of thermoplastic resin with specific hardness (Shore D 40-60) and an outer core layer made of rubber composition with different hardness (Shore D 30-50). This segmentation allows each layer to perform its specific function - the inner layer provides rebound and initial velocity while the outer layer controls spin and softens the feel on impact.
Solution Approach 2:
Different materials with specific local properties are used in different regions of the core. The inner core layer uses thermoplastic resin with controlled hardness to optimize rebound, while the outer core layer uses rubber composition to reduce spin and improve feel. Each layer's material properties are specifically tailored to its functional requirements rather than using a uniform material throughout.
3Strength
If the outer core layer hardness is increased to improve rebound, then the initial velocity decreases and distance is not achievable
Solution Approach 1:
The hardness parameters of both core layers are precisely controlled within specific ranges. The inner core layer has Shore D hardness of 40-60 and the outer core layer has Shore D hardness of 30-50. By optimizing these hardness parameters within defined ranges, the patent achieves the right balance between rebound and initial velocity, preventing excessive hardness that would reduce initial velocity while maintaining sufficient rebound.
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 design enhances the ball's rebound and distance traveled while maintaining a good feel on impact, achieving improved flight performance and spin control.
Implementation Method 1
the outer core layer is formed of a rubber composition made primarily of polybutadiene rubber... having a high resilience
Implementation Method 2
owing to the stress concentration associated with deformation on impact by a driver (W#1) or the like that arises in the outer core layer, it is necessary to use in the outer core layer a material which has a high resilience
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 of one or more 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.