Three-Protuberance Wrench for Worn Bolt Slippage
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Solution Overview
Problem
Conventional open-end wrenches are ineffective for wrenching worn bolts due to slippage caused by irregularly blunt bolt heads, and they fail to provide fixed effort points for different wear states of bolts.
Innovation Solution
A three-protuberance open-end wrench design featuring a non-isosceles triangle configuration with two protuberances on one jaw and a single protuberance on the other, positioned asymmetrically to create fixed effort points and minimize slippage, allowing for secure engagement with both ordinary and worn bolts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional open-end wrench with two holding plane faces is used, then it can wrench ordinary hexagonal bolts, but it slips over the corners of worn bolt heads and cannot provide fixed effort points
Solution Approach 1:
The holding face of each jaw is segmented into multiple protuberances (two on the first jaw, one on the second jaw) instead of a single continuous holding surface. This segmentation creates multiple discrete contact points that can adapt to different bolt conditions, preventing slippage on worn bolts while maintaining effectiveness on ordinary bolts.
Solution Approach 2:
The three protuberances are arranged in a non-isosceles triangle configuration, with the second protuberance on the second jaw positioned asymmetrically (not on the central bisector of the two first protuberances). This asymmetric arrangement creates fixed effort points that provide stable force application and prevent slippage, while the non-equal spacing allows adaptation to both ordinary and worn bolt geometries.
2Force
If holding plane faces are made to abut against bolt head, then wrenching force can be applied, but the effort point moves and cannot be fixed for different wear states
Solution Approach 1:
The protuberances are pre-positioned on the holding faces in specific locations that anticipate different bolt wear states. The asymmetric arrangement of the three protuberances creates predetermined effort points that will engage with the bolt head corners regardless of wear, eliminating the need to adjust the wrench for different wear conditions.
3Ease of operation
If boss section is used to hold worn bolt head, then initial contact is made, but the effort point moves and causes slippage over corners
Solution Approach 1:
Instead of using a single boss section with uniform properties, the holding face has localized protuberances with different positions and configurations. The two first protuberances are positioned differently from the second protuberance, creating localized contact points with optimal properties for different regions of the bolt head, preventing slippage while maintaining ease of operation.
Data Source
AI summary
A three-protuberance open-end wrench includes a head section. The head section has a first jaw and a second jaw. Two first protuberances are front and rear, side by side, formed on a holding face of the first jaw. A second protuberance is formed on a holding face of the second jaw. A throat is formed between the holding faces of the first and second jaws for receiving a threaded member therein. The protuberances of the first and second jaws serve to hold the threaded member. The protuberances form a non-isosceles triangle.