Two-Piece Golf Ball Core Frequency Optimization

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Solution Overview

Problem

Two-piece golf balls fail to provide a soft feel upon impact, particularly for beginners, leading to high mishit frequencies and loss of balls, making them unsuitable for cost-effective options.

Innovation Solution

A two-piece golf ball design with a core and cover, where the secondary natural frequency ratio is optimized to achieve a soft feel by using a rubber composition with specific crosslinking agents and a thermoplastic resin cover, ensuring a Shore C hardness difference and compressive deformation for improved resilience and feel.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If a two-piece golf ball structure is used, then manufacturing cost is reduced and simplicity is improved, but feel at impact upon putting becomes hard

Engineering Contradiction:
Improvemanufacturing costVSAvoidfeel at impact
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by optimizing the secondary natural frequency of the core (NF(2)1) and the golf ball (NF(2)2) to satisfy the formula V = NF(2)2 - NF(2)1 ≤ 1080 Hz. This frequency parameter adjustment allows the two-piece ball to achieve soft feel at impact upon putting while maintaining the simple and cost-effective two-piece structure.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent uses composite materials by combining a core made from rubber composition (containing polybutadiene, zinc oxide, zinc acrylate, and crosslinking agents) with a cover made from thermoplastic resin. This composite structure enables the ball to achieve both low manufacturing cost and soft feel at impact, resolving the contradiction between simplicity and performance.

Inventive Principle:
Principle #40Composite materials

2Strength

If core hardness is increased for resilience, then flight performance is improved, but feel at impact upon putting becomes harder

Engineering Contradiction:
Improvecore resilienceVSAvoidfeel at impact upon putting
Core Design Contradiction:
StrengthVSObject-affected harmful factors

Solution Approach 1:

The patent applies parameter changes by controlling the Shore C hardness of the core within a specific range (50-70) and optimizing the frequency parameters (V ≤ 1080 Hz). This allows the core to provide sufficient resilience for good flight performance while maintaining soft feel at impact upon putting through the balanced hardness and frequency characteristics.

Inventive Principle:
Principle #35Parameter changes

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 golf ball achieves a soft feel upon impact while maintaining low manufacturing costs and excellent flight performance, suitable for both beginners and experienced players.

Implementation Method 1

a core and a cover which are positioned outside the core... feel at impact upon putting is soft

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

rubber composition with specific crosslinking agents... improved resilience and feel

Methodology Applied
Scientific EffectViscoelasticity: Viscoelasticity

Implementation Method 3

rubber composition with specific crosslinking agents... improved resilience

Methodology Applied
Scientific EffectCrosslinking: Chemical Bonding

Implementation Method 4

amount of compressive deformation... improved resilience and feel

Methodology Applied
Scientific EffectEnergy storage in elastic deformation: Elasticity

Data Source

PatentEP3181199B1Two-piece golf ball
Publication Date: 2018.12.12 SUMITOMO RUBBER INDUSTRIES LTD
  • EP3181199B1 patent drawingFigure 1
  • EP3181199B1 patent drawingFigure 2
  • EP3181199B1 patent drawingFigure 3

AI summary

A golf ball (2) includes a core (4) and a cover (6). A value V calculated by the following mathematical formula is equal to or less than 1080 Hz. V = NF(2)2 - 2/3 *NF(2)1 In the mathematical formula, NF(2)1 represents a secondary natural frequency of the core (4), and NF(2)2 represents a secondary natural frequency of the golf ball (2). A difference (H1s-H1o) between a Shore C hardness (H1s) at a surface of the core (4) and a Shore C hardness (H1o) at a central point of the core (4) is equal to or greater than 10. An amount of compressive deformation (Df1) of the core (4) is equal to or greater than 4,1 mm.