Threaded Engagement Device with Curved Load Flanks
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Solution Overview
Problem
Conventional threaded engagement devices experience stress concentration at the foot of the load flanks, leading to thread damage and premature failure when subjected to external forces, especially during loosening, resulting in reduced usage life.
Innovation Solution
The threaded engagement device features a female thread portion with a straight and concave rounded root, and a male thread portion with a concave rounded root of larger radius, along with load flanks making a negative angle with the perpendicular axis, to distribute stress and prevent disengagement, thereby enhancing stability and longevity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the load flank is formed as a straight line with a positive angle, then the threaded engagement can be easily assembled, but stress concentration occurs at the foot of the load flank causing thread damage and reduced usage life
Solution Approach 1:
The patent applies curvature by forming the load flank as a curved surface instead of a straight line. Specifically, the load flank is designed with a radius of curvature R1 that is larger than the radius of curvature R2 of the stab flank, creating a smooth transition that distributes stress evenly along the flank and eliminates stress concentration at the foot of the load flank, thereby preventing thread damage and extending usage life while maintaining ease of assembly
2Ease of operation
If the load flank makes a positive angle with the perpendicular axis, then assembly is facilitated, but the threaded engagement can be easily released by small external forces during loosening
Solution Approach 1:
The curved load flank with positive angle α relative to the perpendicular axis creates a mechanical interlocking effect. The curvature radius R1 is specifically designed to be larger than the curvature radius R2 of the stab flank, which generates a wedging action that resists external forces during loosening attempts, thereby maintaining engagement stability while preserving ease of assembly
3Device complexity
If the root is formed with a small radius of curvature, then the thread structure is compact, but stress concentration occurs leading to premature failure
Solution Approach 1:
The patent optimizes the root geometry by forming it with a specific radius of curvature that balances compactness and stress distribution. The root curvature is designed to seamlessly connect the stab flank and load flank, creating a smooth transition zone that eliminates stress concentration points while maintaining a compact thread structure, thereby preventing premature failure without increasing device complexity
Data Source
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AI summary
The threaded engagement device of the present invention comprises a female thread portion and a male thread portion, which are engaged to each other through a plurality of threads formed along the axis direction. Each thread of the female thread portion and the male thread portion of the threaded engagement device comprises a crest, a root, a stab flank and a load flank. The root of the female thread portion comprises a straight portion extending along the axis direction and a concave rounded portion. The root of the male thread portion comprises a concave rounded portion, wherein the radius of curvature of the rounded portion formed in the root of the male thread portion is larger than the radius of curvature of the rounded portion formed in the root of the female thread portion.