Racket Frame Common-Hole Geometry for Longer String Length
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Solution Overview
Problem
Existing racket frames have through holes that cause strings to be bent at large angles, resulting in shortened effective lengths and difficulties in stringing, pattern restrictions, and reduced workability.
Innovation Solution
The frame design includes common holes and tubular portions with elongated inner openings in the circumferential direction, allowing main and cross strings to be extended without significant bending, facilitating longer effective lengths and improved stringing ease.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the string is inserted into the inclined through hole, then the string can be fixed at the bending position, but the effective length of the string becomes short
Solution Approach 1:
The invention changes the geometric parameters of the hole opening by making the opening dimension in the circumferential direction larger than the opening dimension in the thickness direction. This parameter change allows the string to pass through with reduced bending angle, thereby increasing the effective length while maintaining ease of stringing
Solution Approach 2:
The invention transitions from a conventional circular hole opening to an elongated opening with asymmetric dimensions. By making the circumferential opening dimension larger than the thickness opening dimension, the string can traverse the hole with a more favorable path, reducing bending and increasing effective length
2Reliability
If the string is bent at a large angle at the inner peripheral side forming edge of the frame, then the string can be fixed in the through hole, but the working performance of the racket is reduced
Solution Approach 1:
By changing the opening parameters of the hole to have a larger circumferential dimension than thickness dimension, the string bending angle at the inner peripheral side is reduced. This maintains adequate string fixation while eliminating the harmful effect of excessive bending that degrades hitting feel and control
Data Source
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AI summary
To make the effective lengths of a main string and a cross string long. A racket frame (10) includes a frame main body (11) having a loop shape. The frame main body is provided with a plurality of holes (18), a plurality of main strings (21) extend in an up-down direction and are arranged in a right-left direction and a plurality of cross strings (22) extend in the right-left direction and are arranged in the up-down direction. The plurality of main strings and the plurality of cross strings are arranged to be extended in the tensioned state inside the frame main body via the plurality of holes. Through a common hole (19), out of the plurality of holes, any one of the plurality of main strings and any one of the plurality of cross strings are inserted. A shape of an inner opening (19a) of the common hole (19) on an inner peripheral surface (11c) of the frame main body is formed such that an opening dimension in a circumferential direction of the frame main body is larger than an opening dimension in a thickness direction of the frame main body.