Multi-piece Golf Ball with Segmented Core for Spin Control
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Solution Overview
Problem
Existing golf balls made from injection-moldable thermoplastic resin cores do not achieve sufficient performance, particularly in spin rates for iron and approach shots.
Innovation Solution
A multi-piece golf ball design featuring a center made from a thermoplastic resin composition with multiple envelope layers, where the hardness of each layer is strategically distributed to reduce spin rates on iron shots and increase spin rates on approach shots, achieved by forming n envelope layers with specific Shore D hardness values.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a single thermoplastic resin core is used, then manufacturing simplicity is maintained, but spin rate control for different shot types deteriorates
Solution Approach 1:
The core is divided into multiple segments (first core, second core, third core) with different hardness values and material compositions. Each segment serves a specific function: the softer first core reduces spin on iron shots, the harder second core provides structure, and the third core adjusts overall compression. This segmentation allows the golf ball to exhibit different spin characteristics for different shot types while maintaining manufacturability through modular construction.
Solution Approach 2:
Different regions of the core have different material properties - the first core has lower hardness (40-60 Shore D) for reduced spin, while the second core has higher hardness (60-80 Shore D) for structural support. The third core's properties are specifically tuned to achieve desired compression characteristics. This local differentiation of material qualities enables optimized performance for various shot conditions.
2Strength
If a harder core is used, then structural integrity is improved, but spin rate on iron shots increases
Solution Approach 1:
The core structure is segmented into a softer first core (40-60 Shore D) surrounded by a harder second core (60-80 Shore D). The softer first core contacts the clubface during iron shots, reducing spin generation, while the harder second core provides the necessary structural integrity and compression resistance. This segmentation resolves the contradiction by assigning different hardness functions to different core regions.
3Object-generated harmful factors
If a softer core is used, then spin rate on iron shots is reduced, but structural integrity deteriorates
Solution Approach 1:
The core is segmented into an inner first core with softer hardness (40-60 Shore D) for spin reduction and an outer second core with harder hardness (60-80 Shore D) for structural support. The softer first core effectively reduces spin on iron shots, while the harder second core maintains overall structural integrity and prevents excessive deformation during impact.
Solution Approach 2:
The core uses a composite structure combining different thermoplastic resin materials with distinct hardness properties. The first core uses a softer thermoplastic resin to reduce spin, while the second core uses a harder thermoplastic resin for structural strength. This composite material approach allows simultaneous achievement of spin reduction and structural integrity.
4Adaptability or versatility
If multiple envelope layers with different hardness are used, then spin rate control is improved, but device complexity increases
Solution Approach 1:
The envelope is divided into multiple layers (first envelope layer, second envelope layer, third envelope layer) with progressively different hardness values and material compositions. Each layer contributes to spin control for different shot types: the first envelope layer affects iron shot spin, the second envelope layer fine-tunes performance, and the third envelope layer provides final optimization. This segmentation enables sophisticated spin control while maintaining a systematic manufacturing approach.
Data Source
Figure 1
AI summary
An object of the present invention is to provide a golf ball showing a low spin rate on driver shots and a high spin rate on approach shots. The present invention provides a multi-piece golf ball comprising a center and n (n is a natural number of 3 or more) envelope layers covering the center, wherein material hardness of the envelop layers satisfies H2<H0<Hn-1; where the envelope layers formed in order from the center side are referred to as a first envelope layer, a second envelope layer, a third envelope layer, a fourth envelope layer, ...an n-1th envelope layer and an nth envelope layer (the outmost layer), respectively and H0 is a material hardness (Shore D hardness) of the center, and H1, H2, H3, H4, ...Hn-1 and Hn are material hardness (Shore D hardness) of the first envelope layer, the second envelope layer, the third envelope layer, the fourth envelope layer, ...the n-1th envelope layer and the nth envelope layer (the outmost layer), respectively ; and the center is formed from a thermoplastic resin composition, and the second envelope layer is formed from a thermoplastic resin composition or a rubber composition.