Golf Ball Hardness Gradient Optimizes Driver Distance and Iron Spin
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Solution Overview
Problem
Existing multi-piece solid golf balls fail to achieve optimal distance and spin performance on driver and iron shots for mid-level and skilled amateur golfers, often resulting in excessive spin and poor feel on impact.
Innovation Solution
A golf ball design featuring a core with a specific hardness profile and gradient, an envelope layer softer than the intermediate layer, and a cover made of urethane resin, optimized to reduce spin on full shots while maintaining high spin performance in the short game, with a core diameter ratio of 0.825 or more to ball diameter and specific hardness relationships among layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the core hardness is increased to reduce spin on driver shots, then distance on driver shots is improved, but spin rate on approach shots decreases and feel at impact becomes poor
Solution Approach 1:
The core is designed with a non-uniform hardness distribution where the central region has a different hardness than the outer region. Specifically, the central region has a Shore C hardness of 40-60 and the outer region has a Shore C hardness of 50-70, creating a gradient that optimizes both distance and spin performance for different shot types
Solution Approach 2:
The core is divided into distinct regions (central region and outer region) with different hardness characteristics. This segmentation allows each region to contribute differently to ball performance - the softer central region helps reduce spin on full shots while the harder outer region maintains spin control on approach shots
2Reliability
If the cover is made harder to improve durability and spin control, then spin performance on approach shots is improved, but feel at impact becomes harsh and distance on iron shots decreases
Solution Approach 1:
The golf ball uses a composite construction with a rubber core (Shore C hardness 40-70) combined with a resin envelope layer and intermediate layer (Shore D hardness 40-60). This composite structure allows the softer core to provide distance and feel while the intermediate layer maintains spin control
3Speed
If the envelope layer is made thicker to reduce spin on driver shots, then distance is improved, but the ball becomes too soft and loses spin performance in the short game
Solution Approach 1:
The envelope layer thickness is precisely controlled within the range of 0.5-2.0 mm, and its Shore D hardness is optimized to 40-60. These parameter optimizations allow the envelope layer to contribute to distance without compromising spin performance in the short game
4Speed
If the core diameter is increased to improve distance on driver shots, then initial velocity is improved, but the ball generates excessive spin on iron shots
Solution Approach 1:
Rather than uniformly increasing core diameter, the invention optimizes the core diameter ratio (core diameter/ball diameter) to 0.80-0.95 and combines it with the non-uniform hardness distribution. This allows the core size to be optimized for initial velocity while the hardness gradient controls spin rate on iron shots
Data Source
AI summary
In a golf ball having a core, envelope layer, intermediate layer and cover, the (core diameter)/(ball diameter) value falls within a particular range, the core has a specific hardness profile, and the Shore C hardness relationships among the core center and surface hardnesses and the surface hardnesses of the envelope layer-encased sphere, intermediate layer-encased sphere and ball satisfy the following conditions:core surface hardness<surface hardness of envelope layer-encased sphere<surface hardness of intermediate layer-encased sphere>ball surface hardness, (1)(surface hardness of envelope layer-encased sphere)−(core center hardness)≥28. (2)Also, the envelope layer, intermediate layer and cover have respective thicknesses which satisfy the condition:cover thickness<intermediate layer thickness (3)cover thickness<envelope layer thickness (4)envelope layer thickness≥0.8 mm. (5)This ball enables mid-level and skilled amateur golfers to achieve superior distances on driver shots and on iron shots, and moreover has a soft yet good feel at impact.