Open-End Wrench Recess Geometry for Damaged Screw Corners
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Solution Overview
Problem
Traditional wrenches slip easily on screws with damaged edges, leading to deformation or damage of screw edges and rendering them unusable, posing a challenge in maintenance operations.
Innovation Solution
The open-end wrench features angled driving surfaces with concave sharp recesses and an arcuate groove, allowing it to grip screws with minor or extensive edge damage, enhancing grip and reducing slipping.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional wrenches are used on screws with damaged edges, then the wrench can be applied to the screw, but the wrench tends to slip and exacerbate damage to the screw edges
Solution Approach 1:
The driving surfaces are equipped with concave sharp recesses at specific locations to provide localized gripping points. This local modification allows the wrench to engage with damaged screw edges more effectively, concentrating the gripping force at the recesses rather than relying on the entire surface, thereby preventing further edge damage while maintaining grip stability.
Solution Approach 2:
The arcuate groove with curvature greater than π/2 radians provides a curved gripping path that accommodates damaged screw edges. This curvature allows the wrench to maintain contact and grip stability even when the screw edges are irregular or damaged, preventing slipping that would otherwise exacerbate edge damage.
2Productivity
If considerable force is applied to remove rusted screws, then the screws can be loosened, but the wrench becomes prone to slipping and deforming screw edges
Solution Approach 1:
The concave sharp recesses provide localized engagement points that can grip damaged or rusted screw edges securely. This allows maintenance personnel to apply considerable force to loosen rusted screws without the wrench slipping and deforming the screw edges, thereby maintaining productivity while preventing harmful deformation.
Solution Approach 2:
The arcuate groove and sharp recesses are pre-configured to provide optimal gripping geometry before force is applied. This preliminary structural arrangement ensures that when force is applied to remove rusted screws, the wrench maintains stable engagement through the curved groove and recesses, preventing edge deformation during the high-force removal operation.
3Ease of operation
If traditional wrenches are used on screws with extensive edge damage, then the wrench may still grip the screw, but the screw becomes unusable and must be discarded
Solution Approach 1:
The concave sharp recesses are strategically positioned to engage with remaining intact portions of extensively damaged screw edges. This localized gripping approach allows the wrench to maintain grip capability on screws with extensive damage, applying force through the recesses to turn the screw without completely destroying it, thereby preserving screw usability that would otherwise be lost.
Solution Approach 2:
The arcuate groove with its curved geometry provides a flexible gripping path that can accommodate extensively damaged screw edges. This curvature allows the wrench to find and maintain engagement with remaining sound portions of the screw, enabling operation without completely destroying the screw and preserving its usability.
Data Source
AI summary
An open-end wrench includes a working head and a handle which is formed with the working head. The working head includes an open slot which is formed by multiple driving surfaces, and has an access opening. An arcuate groove is formed between adjacent driving surfaces. Each driving surface has a concave sharp recess that forms an angle less than 90 degrees. The sharp recess is located in the middle of the driving surface corresponding thereto for gripping corners of screws. When in use, even if the screw corners are extensively damaged, the angled sharp recesses can find a gripping point to assist in turning the screw.