Range-Taking Shear Bolts for Controlled Torque Cable Clamping
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Solution Overview
Problem
Existing electrical connector systems face challenges in securely connecting a range of conductor sizes without damaging the cables, as they often require precise torque control and consistent shearing of bolts to ensure both mechanical and electrical integrity.
Innovation Solution
The development of range taking shear bolts with a hollow cylindrical body featuring a continuous screw thread and longitudinal spline teeth, which shear at a predetermined torque value, allowing for secure clamping and easy removal, and a corresponding drive tool that controls the insertion depth to ensure consistent shearing within a specific zone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a bolt is used to secure conductors in electrical connectors, then mechanical connection strength is improved, but precise torque control is required to prevent cable damage
Solution Approach 1:
The bolt is designed with a predetermined shear torque value that changes based on wall thickness. By varying the wall thickness parameter, the bolt automatically adjusts its shear torque characteristic to match different conductor sizes and cable types, eliminating the need for precise manual torque control
Solution Approach 2:
The bolt automatically shears at its predetermined torque value without requiring external torque measurement or control equipment. The shear mechanism serves itself by using the bolt's own structural design (wall thickness between screw thread and spline teeth) to define the torque limit, making the system self-regulating
2Ease of manufacture
If a shear bolt is designed to break at a specific torque, then torque control is simplified, but manufacturing precision of the shear zone is critical
Solution Approach 1:
The bolt has different structural qualities at different locations: the screw thread portion has one wall thickness characteristic while the spline teeth portion has another. The wall thickness in the shear zone (between screw thread and spline teeth) is specifically designed to be the critical parameter that determines shear torque, concentrating the precision requirement in a localized, easily controllable region
Solution Approach 2:
The shear zone is pre-designed during manufacturing with a specific wall thickness that predetermined the shear torque value. This preliminary structural design ensures consistent shear behavior without requiring complex post-manufacturing adjustments or quality control procedures
3Ease of operation
If a hollow cylindrical bolt with internal splines is used, then drive tool integration is improved, but structural complexity increases
Solution Approach 1:
The drive tool is nested inside the hollow cylindrical body of the bolt. The spline teeth on the inner surface of the bolt engage with complementary splines on the drive tool, creating a nested configuration that allows the drive tool to be inserted and rotated within the bolt's hollow space, providing secure torque transmission
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
This solution enables secure connections across various conductor sizes, ensuring both mechanical and thermal stability while allowing for easy removal of the bolt head, addressing the limitations of existing systems by providing controlled torque and consistent shearing without the need for a torque wrench.
Implementation Method 1
the wall configured to shear is within a predetermined shear zone when an applied torque reaches or exceeds a predetermined torque value
Data Source
AI summary
Range taking shear bolts and bolt installation (drive) tools are described herein, which are configured for use with a variety of range taking connectors and conductors.