Multi-piece Golf Ball Core Segmentation for Distance and Spin
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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, leading to inadequate performance on full shots.
Innovation Solution
A multi-piece solid golf ball design featuring a thermoplastic resin inner core layer with specific hardness and diameter ranges, combined with a polybutadiene rubber outer core layer, optimized for high resilience and hardness distribution, along with a cover layer for enhanced rebound and distance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the inner core layer is made hard to improve spin rate and feel, then spin performance is improved, but initial velocity and distance decrease
Solution Approach 1:
The core is divided into two distinct layers: an inner core layer made of hard thermoplastic resin (Shore D 55-90) for spin control and feel, and an outer core layer made of soft rubber composition (Shore D 20-40) for initial velocity and distance. This segmentation allows each layer to optimize its function without compromising the other.
Solution Approach 2:
Different regions of the core have different material properties tailored to their specific functions. The inner core layer has high hardness for spin generation during the rolling phase, while the outer core layer has low hardness for maximizing compression and rebound velocity during impact. The cover layer also has specific hardness (Shore D 40-70) optimized for its protective and aerodynamic functions.
2Speed
If the center core is made soft to improve initial velocity, then distance performance is improved, but spin rate and feel deteriorate
Solution Approach 1:
The core is divided into two distinct layers: an inner core layer made of hard thermoplastic resin (Shore D 55-90) for spin control and feel, and an outer core layer made of soft rubber composition (Shore D 20-40) for initial velocity and distance. This segmentation allows each layer to optimize its function without compromising the other.
Solution Approach 2:
Different regions of the core have different material properties tailored to their specific functions. The inner core layer has high hardness for spin generation during the rolling phase, while the outer core layer has low hardness for maximizing compression and rebound velocity during impact.
3Speed
If the inner core layer diameter is increased to improve distance performance, then distance is improved, but spin rate increases excessively
Solution Approach 1:
The core is divided into two distinct layers: an inner core layer made of hard thermoplastic resin (Shore D 55-90) for spin control and feel, and an outer core layer made of soft rubber composition (Shore D 20-40) for initial velocity and distance. This segmentation allows each layer to optimize its function without compromising the other.
Solution Approach 2:
Different regions of the core have different material properties tailored to their specific functions. The inner core layer has high hardness for spin generation during the rolling phase, while the outer core layer has low hardness for maximizing compression and rebound velocity during impact.
4Reliability
If the outer core layer hardness is increased to improve spin performance, then spin rate is improved, but initial velocity and distance decrease
Solution Approach 1:
The core is divided into two distinct layers: an inner core layer made of hard thermoplastic resin (Shore D 55-90) for spin control and feel, and an outer core layer made of soft rubber composition (Shore D 20-40) for initial velocity and distance. This segmentation allows each layer to optimize its function without compromising the other.
Solution Approach 2:
Different regions of the core have different material properties tailored to their specific functions. The inner core layer has high hardness for spin generation during the rolling phase, while the outer core layer has low hardness for maximizing compression and rebound velocity during impact.
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 significantly increases the initial velocity and distance traveled on full shots while maintaining a good feel on impact, achieving improved flight performance and spin control.
Implementation Method 1
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 and a large hardness distribution and readily deforms
Data Source
AI summary
The invention provides a multi-piece solid golf ball composed of a solid core encased by a cover of one or more layer, which solid core has an inner core layer and an outer core layer. The inner core layer is formed primarily of a thermoplastic resin, has a diameter of from 21 to 38 mm, has a JIS-C cross-sectional hardness of from 60 to 83 at any single point on a cross-section obtained by cutting the inner core layer in half, and has a cross-sectional hardness difference between any two points on the cross-section of within ±5. The outer core layer is formed of a rubber composition made primarily of polybutadiene rubber. The solid core has a diameter of from 35 to 42 mm. 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. Such a golf ball is able to achieve an increased distance.