Shear Screw Blind Hole Torque Transmission
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Solution Overview
Problem
Existing shear screws for securing electrical conductors in metallic terminals require complex tools and procedures to ensure sufficient torque and breaking points, often lacking simplicity and versatility for varying conductor sizes.
Innovation Solution
The shear screw design features a blind hole extending to the second predetermined breaking point with a recess offset at an angle, allowing a simple pin-like tool to rotate the screw until the first breaking point is reached for thinner conductors, and then accessible for further rotation to the second breaking point for thicker conductors, ensuring secure fastening without excess projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex tool with outer bell-like supporting means is used to screw tight the shear screw, then the screw can be tightened sufficiently firmly, but the tool complexity increases
Solution Approach 1:
The patent extracts the essential function of torque application from the complex tool system. By providing a simple pin-like tool that fits into the blind hole, only the critical torque transmission function is retained, while unnecessary supporting means are removed. The deformation of the blind hole opening ensures the tool can be inserted only to the correct depth, maintaining reliability without complexity.
Solution Approach 2:
The blind hole acts as an intermediary mechanism that mediates between the simple pin-like tool and the screw tightening function. The deformed opening of the blind hole serves as a depth-limiting intermediary structure that ensures the tool engages correctly without requiring complex guiding or supporting mechanisms.
2Adaptability or versatility
If the blind hole extends to the second predetermined breaking point, then a single tool can secure both thinner and thicker conductors, but the tool insertion control becomes more difficult
Solution Approach 1:
The blind hole opening is deliberately deformed asymmetrically to create a depth-limiting feature. This asymmetric deformation provides a mechanical stop that prevents over-insertion of the tool, making insertion control intuitive and easy without requiring complex guiding mechanisms. The asymmetric shape naturally guides the tool to the correct engagement depth.
3Adaptability or versatility
If the screw has multiple predetermined breaking points with different strengths, then the screw can be sheared off at different positions for different conductor sizes, but the screw structure becomes more complex
Solution Approach 1:
The screw structure incorporates local variations in wall thickness to create predetermined breaking points with different strengths. Instead of making the entire screw structure complex, only specific local regions are modified to create the first and second breaking points. This allows the screw to adapt to different conductor sizes while maintaining overall structural simplicity.
Data Source
AI summary
A shear screw has predetermined breaking points in two planes, separated axially from one another, and it has centrally a blind hole extending over a substantial length and having a cross section which is suitable for transmitting a torque to the shear screw by means of a pin-like tool of adapted dimensions which can be inserted into the blind hole. The blind hole extends to about level with the predetermined breaking point which is arranged in the lower region, facing the end face of the shear screw, of the latter and has a strength greater than that of the other predetermined breaking point.