R-Type Thread Anti-Loosening Design
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Solution Overview
Problem
Existing fasteners are prone to loosening under severe vibration due to lateral clearance in thread engagement, leading to potential damage and safety hazards, and existing solutions have not fundamentally addressed this issue.
Innovation Solution
The R-type thread design features a transition line connecting first and second lead-in side angle lines, forming an R-type arc that reduces stress concentration and increases locking force, with a thread angle greater than or equal to 30°, allowing for better stress distribution and anti-looseness resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a wedge-shaped thread with 30° angle is used to improve self-locking ability, then the anti-loosening performance is improved, but the side force increases causing non-uniform stress and reduced fastener life
Solution Approach 1:
The patent applies curvature by replacing the sharp corner of traditional wedge-shaped threads with a rounded transition line (R-type arc) connecting the lead-in sides. This curvature eliminates stress concentration at sharp corners while maintaining the wedge-shaped profile's self-locking capability, distributing stress more uniformly across the thread engagement surface.
Solution Approach 2:
The patent modifies only the critical transition zone at the thread crest where stress concentration occurs, while maintaining the overall wedge-shaped thread profile. The transition line creates a localized rounded region that reduces side force and stress concentration without altering the fundamental thread geometry or self-locking mechanism.
2Ease of manufacture
If standard thread profiles are used, then manufacturing is simple, but lateral clearance causes loosening under vibration
Solution Approach 1:
The R-type transition line introduces curvature to the thread profile, creating a rounded crest that eliminates lateral clearance between mating threads. This curved geometry maintains simplicity of manufacture while fundamentally improving vibration resistance by preventing the lateral movement that causes loosening in standard threads.
3Force
If thread angle is increased to improve locking force, then anti-looseness friction force increases, but stress concentration may occur
Solution Approach 1:
The rounded transition line distributes the contact stress over a larger area at the thread crest, reducing stress concentration while maintaining the increased thread angle's beneficial locking force. The curvature creates a gradual transition that spreads the load more evenly across the engaged threads.
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 R-type thread effectively resists vibration-induced loosening, prolongs fastener service life, and provides a high anti-looseness friction force without auxiliary locking elements, suitable for various thread specifications and temperature changes.
Implementation Method 1
the transition line is concaved in a direction away from a crest of the tooth... the tooth tip of the external (internal) thread can be effectively protected... Local stress of a single tooth pattern is quite large, causing un-uniform stresses of teeth of the thread
Implementation Method 2
the generated anti-loose friction force will be inevitably increased significantly
Data Source
AI summary
An R-type thread belongs to the field of fasteners. Both lateral sides of a thread tooth form are a first lead-in side angle line and a second lead-in side angle line respectively. The first lead-in side angle line and the second lead-in side angle line are connected through a transition line. The transition line is concaved in a direction away from a crest. The present technical solution overcomes the defect of the existing threads of being easy to get loose after assembled, providing the R-type thread which has the functions of resisting vibration and looseness.