Earthing Nut Thread Geometry for Low-Torque Coating Removal
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Solution Overview
Problem
Existing earthing nuts deform the bolt's thread portion radially to peel off its coating film, leading to high screwing torque and adversely affecting tightening performance.
Innovation Solution
The earthing nut features an irregular-shaped thread portion with a different pitch and inclination angle from the reference thread, allowing it to peel off the bolt's coating film axially without significant radial deformation, thereby suppressing increased screwing torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the earthing nut is plastically deformed so that the inner diameter of the thread portion is small to peel off the coating film of the bolt, then the coating film can be peeled off to secure earth performance, but the screwing torque becomes too high which adversely affects tightening performance
Solution Approach 1:
The internal thread is segmented into two distinct portions: a reference thread portion with standard pitch and inclination angle, and an irregular-shaped thread portion with different pitch and inclination angle. This segmentation allows the irregular-shaped portion to specifically target and peel off the coating film while the reference thread portion maintains normal threading characteristics, thus achieving earth performance without excessive screwing torque
Solution Approach 2:
The deformation is applied locally only to specific portions of the internal thread to create the irregular-shaped thread portion, while other portions maintain their original reference thread characteristics. This localized deformation approach ensures that only the necessary areas are modified to peel off the coating film, preserving the overall threading performance and controlling screwing torque
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
The solution ensures earth performance by peeling off the bolt's coating film while maintaining a stable inner diameter, thus reducing screwing torque and enhancing tightening efficiency.
Implementation Method 1
a deformation step of partly deforming a pressured side flank face in an internal thread provided on a nut by pressing a pin against part of an outer peripheral face of a thread formation portion of the nut
Data Source
AI summary
An earthing nut includes a thread formation portion having an internal thread, wherein the internal thread includes a reference thread portion, and an irregular-shaped thread portion having a shape different from a shape of the reference thread portion, a pitch of the irregular-shaped thread portion is different from a pitch of the reference thread portion, and an inclination angle of a pressured side flank face of the irregular-shaped thread portion is different from an inclination angle of a pressured side flank face of the reference thread portion.