Torque Limiting Set Screw Shear Plane Design
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Solution Overview
Problem
Existing torque limiting fasteners face challenges in accurately setting the break torque, manipulating the fastener after breaking, and achieving precise and predetermined breakage formations.
Innovation Solution
A torque limiting fastener design featuring a controlled break region with a defined shear plane, comprising an outer surface break point and an inner surface break point, which allows for controlled breakage without distorting the inner bore, enabling access for tools post-breakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a torque limiting fastener is designed to break at a predetermined torque, then the torque accuracy is improved, but the manipulation difficulty after breaking increases
Solution Approach 1:
The fastener body is segmented into two parts by the controlled break region with shear plane, allowing the fastener to break into manageable segments at a predetermined torque while maintaining the inner bore integrity for continued tool manipulation
Solution Approach 2:
The controlled break region with defined shear plane is pre-formed in the fastener body before use, ensuring that when the predetermined torque is reached, the fastener breaks in a controlled manner that preserves the inner bore for subsequent manipulation operations
2Manufacturing precision
If the fastener is designed to break controllably, then the breakage precision is improved, but the distortion of inner bore increases
Solution Approach 1:
The controlled break region is localized to a specific area of the fastener body with a defined shear plane, concentrating the breakage action in this local region while preserving the overall integrity and shape of the inner bore for tool access
Solution Approach 2:
The controlled break region with shear plane is pre-formed in the fastener body, ensuring that when breaking occurs at the predetermined torque, it follows the pre-defined path that avoids distorting the inner bore geometry
3Manufacturing precision
If the shear plane is formed between inner bore and outer surface, then the breakage control is improved, but the access to inner bore becomes difficult
Solution Approach 1:
The fastener breaks into segments along the shear plane, but the inner bore remains intact and accessible, allowing tools to be inserted through the broken segments to reach and manipulate components through the inner bore
Solution Approach 2:
The controlled break region is pre-formed to ensure that when breaking occurs, the inner bore maintains its geometry and remains accessible for tool insertion and manipulation, preventing distortion that would block access
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
Enables precise and controlled breakage without obstructing access to the inner bore, allowing for easy manipulation and reuse of the fastener, improving accuracy and usability, especially in applications like 'hot line' work.
Implementation Method 1
The controlled break region includes an outer surface break point formed into the outer surface and an inner surface break point formed into the inner bore. The outer surface break point and the inner surface break point defining a shear plane therebetween.
Implementation Method 2
The controlled break region is positioned between the inner bore and the outer surface, creating a predetermined weak point that concentrates stress at the shear plane during tightening, enabling controlled breakage at a specific torque level.
Data Source
AI summary
A torque limiting fastener comprising a body. The body includes a threadform, an inner bore and a controlled break region. The body defines an elongated body extending from a first end to a second end, and the body includes an outer surface. The threadform extends at least partially between the first end and the second end along the outer surface. The inner bore extends from the second end at least partially toward the first end of the body. The controlled break region is positioned between the inner bore and the outer surface. The controlled break region includes an outer surface break point formed into the outer surface and an inner surface break point formed into the inner bore. The outer surface break point and the inner surface break point defining a shear plane therebetween.