Golf Club Shaft Gravity Center Optimization
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Solution Overview
Problem
The challenge is to improve the hitting ratio and initial velocity of a golf ball while maintaining swingability and feeling during a golf swing, as extending club length to increase head speed compromises control and inertia moment, and simply increasing head weight worsens swingability and bending rigidity.
Innovation Solution
A golf club shaft with a gravity center positioned between 54% and 65% of its length from the tip, weighing 56 grams or more, and a bending rigidity value of 3.6 kgf·m2 or less at 630 mm from the tip, using low elasticity materials with fiber elastic modulus of 20 t/mm2 or less, and specific fiber orientation angles for the butt side, to balance weight and flexibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the club length is extended to increase head speed, then the flight distance of the ball is improved, but the control property of the head is lowered and the hitting ratio is deteriorated
Solution Approach 1:
The patent changes the parameter of shaft gravity center position to between 60-70% of shaft length from the tip, and controls bending rigidity EI to specific ranges, thereby optimizing the balance between head speed and control property without extending club length beyond regulatory limits
Solution Approach 2:
The patent applies different bending rigidity requirements to different sections of the shaft, with specific EI values prescribed at different measurement points (630mm, 730mm, 830mm from tip), creating local variations in flexibility that enhance both speed and control
2Speed
If the head weight is increased to increase initial velocity of the ball, then the flight distance is improved, but the inertia moment of the club is increased and swingability is lowered
Solution Approach 1:
The patent changes the parameter of shaft gravity center position to between 60-70% of shaft length from the tip, which optimizes the weight distribution and moment of inertia, thereby improving swingability while maintaining the ability to generate high initial velocity
Solution Approach 2:
By positioning the shaft gravity center toward the butt end (60-70% from tip), the patent creates a counterbalancing effect that reduces the perceived weight and inertia during swing, improving swingability while still allowing for heavy head design to maximize ball velocity
3Ease of operation
If the thickness of the butt side part of the shaft is increased to move the gravity center to the butt side, then the swingability is improved, but the bending rigidity value EI is increased and feeling at the time of hitting is lowered
Solution Approach 1:
The patent applies different bending rigidity requirements to different sections of the shaft, with specific EI values prescribed at different measurement points (630mm, 730mm, 830mm from tip), creating local variations in flexibility that enhance both swingability and hitting feel
Solution Approach 2:
The patent precisely controls the bending rigidity parameter EI to fall within specific ranges at different shaft sections, thereby decoupling the relationship between gravity center position and overall shaft stiffness, allowing improved swingability without sacrificing hitting feel
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
This configuration enhances hitting ratio and initial velocity, improving the flight distance of the ball while maintaining swingability and feeling, by optimizing the distribution of weight and flexibility in the shaft.
Implementation Method 1
a low elasticity material including fibers with a fiber elastic modulus of 20 t/mm2 or less may be used for a butt side part
Data Source
AI summary
When a distance from a shaft front end to a shaft gravity center point is LG and a full length of the shaft is LS, 0.54≦LG/LS≦0.65 is satisfied. A golf club shaft, wherein a shaft weight is 56 g or more, and a bending rigidity value EI at a point of 630 mm from the shaft front end to the shaft rear end side is 3.6 kgf·m2 or less.