Lock Nut Thread Notch Structure for Anti-Loosening Fastening
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Solution Overview
Problem
Existing screw threads in nuts are prone to loosening over time due to insufficient locking force, leading to inadequate retention.
Innovation Solution
The implementation of a lock nut and screw assembly with an internal thread featuring a locking notch and chamfered or rounded corners, which provides an interference fit when tightened, enhancing the locking force and preventing loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional metric or English screw threads are used in nuts, then the nut can be easily manufactured and assembled, but the locking force is insufficient and the nut loosens over time
Solution Approach 1:
The thread profile is segmented into distinct functional zones: a locking notch portion that engages with the screw thread crest to prevent loosening, and a standard thread portion that maintains compatibility with conventional screws. This segmentation allows the nut to provide both standard assembly functionality and enhanced locking capability simultaneously.
Solution Approach 2:
The thread structure incorporates local quality variations through the locking notch design, where specific regions of the thread profile have modified geometry (the locking notch with its specific angle and depth) to provide superior locking force, while other regions maintain standard thread characteristics for compatibility and ease of manufacture.
2Reliability
If a locking notch with interference fit is implemented in the thread, then the locking force is significantly improved, but the manufacturing precision requirements increase
Solution Approach 1:
The locking notch is designed with specific geometric parameters (angle of 15°±5° relative to the thread axis, controlled depth between 0.5-2.0mm) that create an interference fit mechanism. These parameter changes transform the thread engagement from a simple clearance fit to an interference fit that generates significant locking force while maintaining manufacturability through well-defined tolerances.
3Force
If the bottom wall is spirally distributed along the axial direction, then the interference fit is enhanced and locking force is improved, but the device complexity increases
Solution Approach 1:
The bottom wall of the locking notch is designed with a spiral curvature that follows the axial direction of the nut. This curved geometry creates a progressive interference fit as the nut is threaded onto the screw, enhancing locking force through mechanical engagement while the spiral form factor maintains compatibility with standard threading operations.
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 achieves a self-locking function that significantly reduces the likelihood of nut loosening by creating a strong interference fit between the nut and screw threads, ensuring a stable fastening assembly.
Implementation Method 1
the screw thread crest of the screw body is in interference fit with the bottom wall
Data Source
AI summary
A threaded fastening assembly includes a nut body and a screw body. The internal thread of the nut body includes a nut thread crest and a nut thread root. The external thread of the screw body includes a screw thread crest, a screw thread root, a fourth side wall located on one side of the screw thread crest, and a fifth side wall located on the other side of the screw thread crest. A locking notch located on one side of the nut thread crest is arranged on the internal thread. The locking notch includes a first side wall and a bottom wall. One end of the first side wall is connected to the nut thread crest, and the other end of the first side wall is connected to one end of the bottom wall. The bottom wall is spirally distributed around the axis of the nut body.