Negative Hardness Gradient Outer Core for Golf Ball
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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, also known as a negative hardness gradient, from the surface to the center, which allows for unique combinations of compression, feel, and spin.
Innovation Solution
A golf ball design featuring an inner core with a specific hardness range and an outer core layer, both formed from homogenous formulations of diene rubber compositions, with metal salts of carboxylic acids and antioxidants, creating a negative hardness gradient by having a softer surface than center, and a cover layer to achieve desired performance characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a conventional hard surface to soft center hardness gradient is used in the core, then the manufacturing process is well-established and reliable, but the golf ball lacks unique combinations of compression, feel, and spin performance
Solution Approach 1:
The patent inverts the conventional hardness gradient by creating a soft surface to hard center gradient instead of the traditional hard surface to soft center. This is achieved by controlling the curing process differently at the surface versus the center, allowing the surface to remain softer while the center becomes harder, thereby achieving unique compression, feel, and spin characteristics not available with conventional gradients
Solution Approach 2:
The patent applies different curing conditions to different regions of the core material. The surface receives different treatment (such as steam exposure or water mist) compared to the interior, creating localized property variations. This allows the surface to have different hardness characteristics than the center, enabling tailored performance properties in specific zones of the core
2Adaptability or versatility
If a soft skin is created by steam treatment or water mist during molding, then the surface hardness is reduced, but the manufacturing process becomes more complex and time-consuming
Solution Approach 1:
The patent combines the soft skin creation process with the core molding process itself. By incorporating steam treatment or water mist application directly into the molding cycle, the patent eliminates the need for separate soft skin creation steps. The soft surface layer is formed simultaneously with the core structure, integrating multiple functions into a single manufacturing operation
Solution Approach 2:
The patent utilizes changes in temperature and moisture parameters during the molding process to control surface hardness. By adjusting steam temperature, exposure time, or water mist application timing, the patent can precisely control the degree of surface softening without affecting the overall core properties, enabling flexible surface hardness adjustment through parameter optimization
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 enables the production of golf balls with tailored hardness gradients, enhancing resiliency and spin performance while maintaining cost-effectiveness and manufacturing efficiency.
Implementation Method 1
The cores are usually heated and crosslinked to create certain characteristics, such as higher or lower compression
Implementation Method 2
The water allegedly softens the compression of the core by retarding crosslinking on the core surface
Data Source
AI summary
A golf ball including an inner core having a first outer surface and a geometric center is formed from a substantially homogenous formulation such that the inner core generally has a hardness of 35 Shore C to 85 Shore C. An outer core layer is formed around the inner core and has a second outer surface and an inner surface, also formed from a substantially homogenous formulation, such that the outer core layer has a hardness of 55 Shore C to 90 Shore C. A cover layer is disposed about the outer core layer. The hardness of the first outer surface is greater than the hardness of the geometric center to define a “positive hardness gradient,” and the hardness of the second outer surface is substantially the same as or lower than the hardness of the inner surface to define a “negative hardness gradient.”