Golf Ball Core Gradient Quotient Design

Solution Overview

Problem

There is a need for a cost-effective and efficient method to produce a single-layer golf ball core with a soft-to-hard hardness gradient from the surface to the center, which is not currently achievable with existing technologies.

Innovation Solution

A golf ball core formed from a substantially homogenous rubber composition with a soft transition region adjacent to the outer surface, containing 8 to 20 percent trans-polybutadiene isomer, and a core geometric center with a negative hardness gradient, achieved through a specific formulation and curing process that includes the use of trans-polybutadiene isomers and a cure-altering material.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional hard surface to soft center hardness gradient is used in golf ball cores, then manufacturing processes are well-established and reliable, but it is impossible to achieve a soft surface to hard center hardness gradient which is needed for unique performance characteristics

Engineering Contradiction:

Improvehardness gradient directionVSAvoidmanufacturing process complexity

Core Design Contradiction:

Adaptability or versatilityVSEase of manufacture

Solution Approach 1:

The patent inverts the conventional hardness gradient approach by creating a soft surface to hard center gradient instead of the traditional hard surface to soft center gradient. This is achieved by inverting the hardness gradient of the outer core layer relative to the inner core, allowing the outer layer to be softer at the surface and harder at the interface with the inner core, thereby achieving the desired negative overall hardness gradient.

Inventive Principle:

Principle #13The other way round (Inversion)

Solution Approach 2:

The patent applies different hardness characteristics to different regions of the core. The inner core maintains a conventional positive hardness gradient (harder at center), while the outer core layer is designed with a negative hardness gradient (softer at outer surface). This local differentiation of quality allows the overall core to achieve a soft surface to hard center gradient without requiring a complete redesign of core manufacturing.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If multiple layers with different hardness gradients are combined, then unique compression and spin characteristics can be achieved, but the manufacturing process becomes more complex and time-consuming

Engineering Contradiction:

Improveperformance characteristicsVSAvoidmultilayer core structure

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent applies different hardness characteristics to different regions of the core. The inner core maintains a conventional positive hardness gradient (harder at center), while the outer core layer is designed with a negative hardness gradient (softer at outer surface). This local differentiation of quality allows the overall core to achieve a soft surface to hard center gradient without requiring a complete redesign of core manufacturing.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent inverts the conventional hardness gradient approach by creating a soft surface to hard center gradient instead of the traditional hard surface to soft center gradient. This is achieved by inverting the hardness gradient of the outer core layer relative to the inner core, allowing the outer layer to be softer at the surface and harder at the interface with the inner core, thereby achieving the desired negative overall hardness gradient.

Inventive Principle:

Principle #13The other way round (Inversion)

3Manufacturing precision

If a soft transition region with high trans-polybutadiene content is created at the core surface, then feel and compression characteristics are improved, but the manufacturing process requires precise control of curing conditions

Engineering Contradiction:

Improvehardness gradient controlVSAvoidcuring process control

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent utilizes parameter changes in the curing process to achieve the desired hardness gradient. By controlling the curing temperature profile and trans-polybutadiene content (8-20%) in the outer core layer, the patent creates a soft transition region at the surface that gradually transitions to a harder center. This parameter control allows precise manipulation of the negative hardness gradient without requiring overly complex manufacturing equipment.

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 solution allows for the creation of golf balls with unique combinations of compression, feel, and spin, offering a high coefficient of restitution and a negative hardness gradient, enhancing the performance and manufacturing efficiency of golf ball production.

Implementation Method 1

a specific formulation and curing process that includes the use of trans-polybutadiene isomers and a cure-altering material

Methodology Applied

Scientific EffectCuring:

Implementation Method 2

a soft transition region adjacent to the outer surface, containing 8 to 20 percent trans-polybutadiene isomer, and a core geometric center with a negative hardness gradient

Methodology Applied

Scientific EffectHardness gradient formation:

Data Source

PatentUS9480882B2Golf ball multilayer core having a gradient quotient

Publication Date: 2016.11.01 ACUSHNET CO

AI summary

A golf ball including a core having an inner core having an outer surface and a geometric center; and an outer core layer. The outer core layer has an outer surface and includes a soft transition region. An outer cover layer is formed over the core. The soft transition region has a thickness of up to 4 mm, has about 5 to 15 percent trans-polybutadiene isomer, and has a negative hardness gradient of up to about 10 Shore C. The core has an overall positive hardness gradient of about 5 Shore C to 15 Shore C and has a gradient quotient, GQ, defined by the equation:1≤G+T10×COR≤4where G is the overall positive hardness gradient in Shore C, T is the percent of trans-polybutadiene isomer at the core outer surface, and COR is the coefficient of restitution measured at an incoming velocity of 125 ft/s.