Golf Club Shaft Flexural Rigidity and Center of Gravity Optimization
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Solution Overview
Problem
Conventional golf clubs often have inappropriate shaft flex, leading to reduced travel distance and directional instability, as the initial conditions such as launch angle and spin rate are not optimally achieved for various golf players.
Innovation Solution
A golf club design with a center of gravity positioned 20 mm to 30 mm behind a reference plane and a flexural rigidity value between 0.5×10^6 and 1.75×10^6 kgf·mm^2 at 140 mm from the tip, along with a torsional rigidity value ratio within 0.8×10^−2 to 1.2×10^−2, ensuring appropriate head trajectory and directional stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the shaft flex is defined within a given range based on amount of deflection of the entire shaft, then the shaft flex can be standardized, but the travel distance and directional stability are reduced for golf players with head speed outside this range
Solution Approach 1:
The patent applies local quality by focusing the flexural rigidity specification on the shaft tip portion (within 140mm from the tip) rather than the entire shaft. This localized approach allows the shaft to have appropriate flexibility at the critical impact zone while maintaining overall structural integrity, thereby improving both adaptability to different players and reliability of performance.
Solution Approach 2:
The patent changes the parameter specification from overall shaft deflection (amount of static deflection) to flexural rigidity at a specific location (shaft tip portion). By using flexural rigidity value EIt (kgf·mm²) at 140mm from the tip instead of overall deflection measurements, the patent creates a more precise and player-specific shaft characteristic that optimizes both travel distance and directional stability across different skill levels.
2Shape
If the center of gravity is positioned deeper behind the reference plane to increase launch angle, then the launch angle increases, but the directional stability may be compromised
Solution Approach 1:
The patent optimizes the center of gravity position by specifying it must be behind the reference plane by 20mm to 30mm. This precise parameter range achieves the desired launch angle improvement while preventing excessive depth that would compromise directional stability. The combined specification with shaft flexural rigidity ensures both parameters work together synergistically.
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 enhances travel distance and directional stability by achieving a great launch angle and low back spin rate, making the golf club suitable for a range of golf players, including those with average handicaps.
Implementation Method 1
a flexural rigidity value EIt (kgf·mm2) of the shaft at a position 140 mm away from the tip on the head side being 0.5×106 or greater and 1.75×106 or less
Implementation Method 2
a center of gravity of the head being positioned on the back side of the head from the reference plane, and a depth of the center of gravity that is a distance between the reference plane and the center of gravity of the head being 20 mm or greater and 30 mm or less
Data Source
AI summary
A reference state is envisioned in which a golf club is placed on a horizontal plane P with a predetermined lie angle and face angle, and the shaft axis line thereof is disposed within a reference plane that is perpendicular to the horizontal plane P. A center of gravity of the head G is positioned on the back side of the head from the reference plane, and a depth of the center of gravity D that is a distance between the reference plane and the center of gravity of the head G is 20 mm or greater and 30 mm or less. The golf club has a flexural rigidity value EIt (kgf·mm2) of the shaft at a position T3 140 mm away from the tip on the head side being 0.5×106 or greater and 1.75×106 or less. More preferably, a value of a ratio (GIt/EIt) of the flexural rigidity value EIt to a torsional rigidity value GIt of the shaft at a position 140 mm away from the tip on the head side is specified to be 0.8×10−2 or greater and 1.2×10−2 or less.