Golf Ball Hardness Gradient and Dimple Pattern
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Solution Overview
Problem
Golf balls struggle to achieve a balance between long flight distance on driver shots and high controllability on approach shots, especially around the green, with existing designs often compromising durability and spin rate.
Innovation Solution
A golf ball design featuring a spherical core with a rubber layer having a linear hardness distribution, an intermediate layer with higher slab hardness than the cover, and a dimple pattern that satisfies specific mathematical criteria for coefficient of friction, resulting in reduced spin rates and improved durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a core with high resilience is used to improve flight distance, then initial speed is enhanced, but spin rate control on approach shots deteriorates
Solution Approach 1:
The core is designed with a non-uniform hardness distribution where the hardness increases from the center toward the surface. This local variation in material property allows the center to provide high resilience for initial speed while the harder outer region controls spin rate during approach shots
Solution Approach 2:
The hardness parameter of the core is changed radially, creating a gradient from softer center to harder periphery. This parameter change enables different functional zones within the core to optimize both flight distance and approach shot controllability
2Speed
If a core with hardness increasing toward the surface is used to achieve higher launch angle and lower spin rate, then flight distance is improved, but durability deteriorates
Solution Approach 1:
The intermediate layer is designed with locally differentiated properties, being softer near the core to protect against distortion and harder near the cover to maintain durability. This local quality variation resolves the contradiction between protecting the core and ensuring overall ball durability
Solution Approach 2:
The golf ball employs a composite structure with multiple layers having different material compositions and hardness characteristics. The combination of core, intermediate layer, and cover creates a synergistic system that achieves both improved flight performance and enhanced durability
3Ease of operation
If a soft thermoplastic polyurethane cover is used to improve controllability on approach shots, then approach performance is enhanced, but durability deteriorates
Solution Approach 1:
The intermediate layer acts as a mediator between the soft cover and the hard core. It transmits forces appropriately while protecting the core from distortion caused by the soft cover, thus enabling the cover to provide good approach shot controllability without sacrificing durability
4Ease of operation
If the coefficient of friction is increased to improve controllability around the green, then spin rate on approach shots is enhanced, but flight distance on driver shots deteriorates
Solution Approach 1:
The dimple pattern is designed with locally varied characteristics including different sizes, depths, and distributions in different regions of the ball surface. This allows optimization of aerodynamic properties for both driver shots and approach shots, enabling high controllability around the green while maintaining long flight distance
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 flight distance on driver shots while maintaining high controllability on approach shots and improving durability by reducing spin rates and optimizing the coefficient of friction.
Implementation Method 1
at least one layer of the spherical core is a rubber layer formed from a rubber composition, the rubber layer is such that R2 of a linear approximation curve obtained from a least square method is 0.95 or higher, when JIS-C hardness, which is measured at nine points obtained by dividing a thickness of the rubber layer into equal parts having 12.5 % intervals in a radius direction of the spherical core, is plotted against distance (%) from an innermost point of the rubber layer
Implementation Method 2
the golf ball having dimples satisfying the formula (I) reduces a spin rate on driver shots, thereby providing a great flight distance
Implementation Method 3
the golf ball has a coefficient of friction calculated using a contact force tester of 0.35 or more and 0.60 or less
Data Source
AI summary
The present invention provides a golf ball comprising a golf ball body with a spherical core having one or more layers, an intermediate layer disposed outside the spherical core and a cover disposed outside the intermediate layer and a paint film formed on a surface of the golf ball body, and having a friction coefficient calculated using a contact force tester of 0.35 or more and 0.60 or less, wherein the golf ball body has specific plurality of dimples on the surface thereof, at least one layer of the spherical core is a rubber layer having a specific hardness distribution, and the rubber layer has a hardness at the outermost point which is greater than a hardness at the innermost point, and the intermediate layer has a slab hardness (Hm) which is greater than a slab hardness (Hc) of the cover.