Dual Core Golf Ball Shallow Steep Hardness Gradient
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Solution Overview
Problem
Conventional golf ball cores made from thermoset materials have limited ability to achieve varied properties across the core, primarily due to their crosslinked structure, which restricts the creation of desired hardness gradients necessary for unique ball characteristics like compression, feel, and spin.
Innovation Solution
A golf ball design incorporating a thermoplastic inner core layer with a negative hardness gradient and a thermoset outer core layer with a positive hardness gradient, utilizing materials such as ionomers, diene rubber, and gradient-promoting additives to achieve specific hardness profiles that allow for customizable ball properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If thermoset materials with crosslinked structure are used for golf ball cores, then the core structure stability is improved, but the ability to achieve varied hardness properties across the core is limited
Solution Approach 1:
The core is divided into multiple layers with distinct material compositions and hardness gradients. The inner core layer uses thermoplastic material while the outer core layer uses thermoset material, allowing each layer to have independent hardness control and property optimization
Solution Approach 2:
Different regions of the core are assigned different material properties and hardness values. The inner core has a shallower hardness gradient while the outer core has a steeper hardness gradient, creating localized property variations that address different performance requirements in different zones
2Ease of manufacture
If a single material composition is used for the core, then the manufacturing process is simplified, but the ability to create customized ball characteristics is reduced
Solution Approach 1:
The core employs a composite structure combining thermoplastic and thermoset materials in distinct layers. This composite approach enables customized ball characteristics through controlled interfaces and gradient transitions while maintaining manufacturing feasibility through established multi-layer molding techniques
3Manufacturing precision
If thermoplastic material is used for the inner core layer, then the ability to achieve shallow positive hardness gradient is improved, but the material selection range is limited compared to thermoset
Solution Approach 1:
The invention controls the hardness gradient through precise parameter optimization including cooling rates, mold temperature profiles, and material composition ratios. By adjusting these processing parameters, the desired shallow positive hardness gradient is achieved in the thermoplastic inner core layer
Data Source
AI summary
A golf ball including a highly-neutralized thermoplastic inner core layer having a geometric center hardness less than a surface hardness to define a first hardness gradient, an outer core layer formed from a homogenous thermoset composition and having an interior hardness substantially less than an outer surface hardness to define a second hardness gradient, an inner cover layer, and an outer cover layer. Both the first and second hardness gradients are positive and a slope of the second hardness gradient is greater than a slope of the first hardness gradient to define a shallow hardness gradient inner core and a steep hardness gradient outer core layer.