Tennis Racket Grommet Segmentation for High-Rate Spin
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Solution Overview
Problem
Existing tennis rackets struggle to impart high-rate spin efficiently, especially when hitting the ball at positions shifted from the center, leading to low trajectory shots and reduced spin performance.
Innovation Solution
A tennis racket design featuring a frame with grommets that have multiple tubular portions with through holes, allowing for parallel and vertical movement of the strings. The tubular portions are shaped to facilitate high-rate spin by deforming the strings in specific directions upon impact.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the string is passed through conventional grommets with circular holes, then the structure is simple and easy to manufacture, but the string cannot be deformed effectively in specific directions to impart high-rate spin
Solution Approach 1:
The grommet is divided into multiple tubular portions (first, second, third tubular portions) with different hole shapes and orientations. Each tubular portion contains strings that are constrained in specific directions, creating segmented functional zones that work together to generate spin while maintaining manufacturing simplicity.
Solution Approach 2:
Different tubular portions have different local properties: the first tubular portion has a vertically elongated hole for vertical string movement, the second has a horizontally elongated hole for horizontal string movement, and the third has a circular hole for combined movement. This local differentiation enables effective spin generation without complicating the overall grommet structure.
2Device complexity
If the string is constrained to move only in one direction, then the grommet structure is simple, but the string deformation is limited and spin performance is reduced
Solution Approach 1:
The grommet is segmented into multiple tubular portions, each constraining strings in different directions. This segmentation allows the system to achieve complex multi-directional string deformation without requiring a single complex grommet structure, thereby maintaining relative simplicity while maximizing spin rate.
Solution Approach 2:
The invention transitions from single-direction string constraint to multi-directional constraint by adding tubular portions with holes oriented in different dimensions (vertical, horizontal, and circular). This dimensional expansion enables greater string deformation capability without proportionally increasing structural complexity.
3Ease of manufacture
If the through holes are circular, then the grommet is easy to manufacture, but the string cannot be selectively deformed in parallel or vertical directions to optimize spin
Solution Approach 1:
The grommet employs local quality differentiation by using circular holes in the third tubular portion for easy manufacture while using elongated holes (vertical and horizontal) in the first and second tubular portions for precise string deformation control. This local differentiation achieves both manufacturing ease and deformation precision in different zones of the same grommet.
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 racket achieves high-rate spin by deforming the strings in parallel and vertical directions, resulting in improved ball trajectory and spin performance, even when hitting the ball off-center.
Implementation Method 1
upon impact with a ball, the string passed through each of the parallel movement tubular portions becomes greatly deformed in the direction parallel to the face. Thereafter, the string returns to the original shape. By the deformation and the return, high-rate spin is imparted to the ball.
Implementation Method 2
upon impact with a ball, the string passed through each of the vertical movement tubular portions becomes greatly deformed in the direction perpendicular to the face. Meanwhile, deformation, in the direction perpendicular to the face, of the string passed through each of the parallel movement tubular portions is small. Therefore, great pressure is applied to the ball from the string passed through each of the parallel movement tubular portions. By this pressure, high-rate spin is imparted to the ball.
Data Source
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AI summary
A grommet 8 of a racket includes a tubular portion 100a. The tubular portion 100a has a through hole 24a through which a string is passed. The through hole 24a has a base-side opening 26a, a side wall 28a, and a tip-side opening 30a. In the tip-side opening 30a, an inner dimension in a direction parallel to a face is larger than an inner dimension in a direction perpendicular to the face. In the tubular portion 100a, the string is in contact with the side wall 28a from the base-side opening 26a to the tip-side opening 30a.