Golf Ball Core Hardness and Deformation Ratio for Injection Molding
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Solution Overview
Problem
Golf balls with solid cores face challenges in achieving soft feel at impact, especially for beginners, due to issues with core deformation and injection molding failures, particularly at low temperatures and with low surface hardness cores.
Innovation Solution
A golf ball design with a core that has a specific Shore C hardness to Shore C deformation ratio (13.0≤K/S≤24.0) and a cover with Shore D hardness not greater than 62, featuring a two-piece structure with dimples and a mold having support pins to ensure proper moldability and feel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a core with large compressive deformation is used to achieve soft feel at impact, then the feel at impact is improved, but the core deforms significantly during injection molding causing local reduction of space between core and cavity face leading to injection failure
Solution Approach 1:
The patent applies parameter changes by optimizing the surface hardness of the core within a specific range (50-80 Shore C) and controlling the compressive deformation amount (3.0-6.0 mm) to achieve the desired balance between soft feel at impact and prevention of excessive deformation during injection molding. This quantitative parameter optimization resolves the contradiction by finding the optimal operating point that satisfies both requirements.
2Ease of operation
If a core with low surface hardness is used to achieve soft feel at impact upon putting, then the feel at impact is improved, but the core is locally radially enlarged near the pole during injection molding causing injection failure
Solution Approach 1:
The patent resolves this contradiction by precisely controlling the surface hardness parameter within 50-80 Shore C and the compressive deformation within 3.0-6.0 mm. This parameter optimization ensures the core is soft enough for comfortable putting feel while maintaining sufficient structural integrity to prevent local radial enlargement during injection molding.
Solution Approach 2:
The patent applies preliminary action by pre-setting the core's surface hardness and compressive deformation characteristics before the injection molding process. This preliminary preparation ensures the core has the appropriate mechanical properties to withstand the injection process without excessive deformation, while still providing the desired soft feel during golf play.
3Ease of operation
If a cover with small volume is used to achieve soft feel at impact, then the feel at impact is improved, but the space between core and cavity face is small causing failure of injection
Solution Approach 1:
The patent resolves this contradiction by optimizing multiple parameters simultaneously: controlling the cover hardness (not greater than 62 Shore D), limiting the cover volume (0.5-3.0 cm³), and adjusting the core surface hardness and compressive deformation. This multi-parameter optimization ensures adequate injection space while maintaining the soft feel characteristics.
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 provides excellent feel at impact for shots with drivers and putters, while maintaining good moldability and resilience, reducing the likelihood of injection failures and enhancing the overall performance of the golf ball.
Implementation Method 1
the core significantly deforms by injection pressure. The core is locally radially enlarged
Implementation Method 2
A melted resin composition is injected into the space between the core and the cavity face. The resin composition is solidified, whereby the cover is molded.
Implementation Method 3
When the core is sufficiently pressed by the support pins, the core is inhibited from being radially enlarged near each pole.
Data Source
AI summary
A golf ball 2 includes a core 4 and a cover 6 positioned outside the core 4. The cover 6 is molded in a mold having support pins by injection molding. A ratio (K/S) of a surface hardness K of the core 4 to an amount of compressive deformation S of the core 4 satisfies the following mathematical formula.13.0≤K/S≤24.0The cover 6 has a hardness H of not greater than 62. A product (α*V) of a latitude α of each support pin and a volume V of the cover 6 is not less than 300.