Wrench Shaft Structural Profile for High Torque
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Solution Overview
Problem
Conventional wrenches have limited structural strength and are unable to apply high torque due to a short moment arm and lack of strength reinforcement, making them unsuitable for large fastening elements.
Innovation Solution
A wrench design featuring a shaft significantly longer than the handle, with a cross-sectional profile of greater outer thickness and smaller inner thickness, and arc-shaped slots to enhance structural strength and prevent stress concentration, allowing for high torque operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the shaft length is increased to provide greater torque, then the torque capability is improved, but the structural strength deteriorates
Solution Approach 1:
The shaft is designed with non-uniform cross-section, featuring greater thickness at the outer side and smaller thickness at the inner portion. This local variation in material distribution concentrates structural strength where needed (at the outer perimeter) while maintaining overall shaft length for torque application, resolving the contradiction between length and strength.
Solution Approach 2:
Instead of simply increasing shaft diameter throughout (one-dimensional solution), the patent introduces a two-dimensional cross-sectional profile variation with slots. This creates an optimized moment of inertia distribution that provides both the length needed for torque and the structural strength through strategic material placement.
2Strength
If the shaft cross-section is reinforced to increase structural strength, then the strength is improved, but the weight increases
Solution Approach 1:
The shaft cross-section features slots that remove material from the inner portion while maintaining outer thickness. This local material redistribution reduces weight compared to a solid shaft of equivalent outer dimensions, while the concentrated material at the outer perimeter maintains structural strength for torque resistance.
Solution Approach 2:
The shaft cross-section is segmented into regions of different thickness through the slots. This segmentation allows material to be positioned only where structurally necessary (outer perimeter for torque resistance), removing unnecessary inner material to reduce weight.
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 wrench to handle high torque applications with increased structural strength and reduced weight, providing a longer moment arm for greater torque and preventing damage from stress concentration.
Implementation Method 1
a cross section of the slot is arc-shaped in order to prevent sharp edges at the walls of the slot and the condition of stress concentration
Data Source
AI summary
A high strength wrench includes a head portion, a shaft and a handle. A length of the shaft is multiple times of a length of the handle. At least one slot extends along a longitudinal direction of the shaft and is formed at a circumferential surface of the shaft. A cross section shape of the shaft has a structural profile of an outer side with a relatively greater thickness and an inner portion of a relatively smaller thickness. Accordingly, the shaft has a greater structural strength to allow the wrench to bear operations of high torque.