Golf Ball Dual Core with Metal-Loaded Thermoplastic Center
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Solution Overview
Problem
There is a continuing need for improved core constructions in golf balls that provide a combination of high resiliency and spin control, with specific gravities and mass densities that enhance flight distance and shot accuracy.
Innovation Solution
The development of multi-layered golf balls featuring a dual core structure, where the inner core is made from a thermoplastic ethylene acid copolymer/plasticizer/metal composition and the outer core layer is made from a thermoset rubber composition, with specific hardness gradients and specific gravity values to optimize Coefficient of Restitution (CoR) and compression properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the core is made from highly resilient rubber material to increase CoR and flight distance, then resiliency is improved, but spin control capability deteriorates
Solution Approach 1:
The core is divided into multiple layers with different material compositions and properties. The inner core layer uses highly resilient rubber material for high CoR, while the outer core layer uses a different material to provide spin control, allowing each layer to optimize for its specific 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 has high resiliency for energy return, while the outer core has different characteristics for spin management, creating local optimization of properties throughout the core structure
2Reliability
If the specific gravity of the core is increased to enhance spin rate control, then spin control is improved, but flight distance capability deteriorates
Solution Approach 1:
The core is segmented into layers with different specific gravity values. The inner core layer has one specific gravity optimized for flight distance, while the outer core layer has a different specific gravity optimized for spin control, allowing both contradictory requirements to be satisfied in different regions
Solution Approach 2:
Different specific gravity values are applied to different regions of the core. The inner core region has properties optimized for energy return and flight distance, while the outer core region has properties optimized for spin rate control, creating local property optimization
3Reliability
If a multi-layered core structure is implemented to balance resiliency and spin control, then both properties are improved, but device complexity increases
Solution Approach 1:
The core is divided into a limited number of layers (typically two or three) with distinct material compositions, each layer serving a specific function. This segmentation provides the necessary property differentiation while maintaining a manageable structural complexity that can be manufactured with existing technology
Data Source
AI summary
Multi-piece golf balls containing a dual-layered core structure are provided. The core structure includes a small, heavy inner core (center) having a relatively high specific gravity, and a surrounding outer core layer. The layers of the core structure may have different hardness gradients. The center of the core comprises a metal material such as copper, steel, brass, tungsten, titanium, aluminum, and alloys thereof preferably dispersed in a thermoplastic polymeric matrix. Different plasticizers such as fatty acid esters may be used. The outer core layer is preferably formed from a thermoset composition such as polybutadiene. The resulting ball has high resiliency and good spin.