Tapered Thread Connection Anti-Loosening Design
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Solution Overview
Problem
Existing threaded fasteners suffer from low self-locking capability, low loading capability, and ease of unthreading, especially under frequent shocks, leading to loose connections and potential security incidents.
Innovation Solution
A tapered external thread and screw hole connecting structure featuring a right trapezoidal external thread and internal thread design, with a cone angle between the external helical surfaces that ensures interference fitting and self-locking, providing enhanced connection, locking, anti-loosening, and sealing performance through conical surface matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional cylindrical threads are used, then the structure is simple and easy to manufacture, but the self-locking capability and loading capability are low, making the connection prone to loosening under shock
Solution Approach 1:
The patent changes the fundamental geometric parameter of the thread from a cylindrical shape to a tapered conical shape. The external thread and internal thread both have tapered surfaces with specific cone angles, transforming the thread geometry to achieve interference fitting and enhanced self-locking capability while maintaining manufacturing feasibility through standard tapered thread processing methods
Solution Approach 2:
The patent introduces conical/tapered surfaces instead of cylindrical surfaces for both external and internal threads. The tapered geometry creates a wedge effect that generates radial interference force, improving self-locking and anti-loosening performance while the conical shape allows for effective stress distribution under loading conditions
2Strength
If conventional threads are used, then the manufacturing process is simple, but the loading capability is insufficient and unthreading occurs easily under frequent shocks
Solution Approach 1:
The patent modifies the thread geometry parameters by implementing tapered external and internal threads with specific cone angles. This geometric transformation creates interference fitting that significantly enhances loading capability and resistance to unthreading under shock, while the tapered thread form remains compatible with conventional manufacturing processes
Solution Approach 2:
The patent creates a composite thread structure where the tapered external thread and tapered internal thread work together as an integrated system. The combination of both tapered surfaces generates synergistic interference fitting and self-locking effects, improving overall connection strength beyond what either component could achieve alone
3Reliability
If standard fasteners are used, then the structure is simple, but the anti-loosening performance is poor and connections become loose under vibration and shock
Solution Approach 1:
The patent changes the thread geometry from standard cylindrical forms to tapered conical forms with specific cone angles. This parameter modification creates continuous interference fitting that maintains tight connection under vibration and shock, significantly improving anti-loosening performance while the overall connection structure remains relatively simple
Solution Approach 2:
The tapered thread design enables self-locking functionality where the interference fitting and wedge effect automatically prevent loosening without requiring additional locking mechanisms or complex anti-loosening features. The connection structure serves its own locking function through its geometric design
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 tapered-thread connection achieves high locking force, high loading capability, good anti-loosening properties, and improved mechanical sealing, preventing unthreading and ensuring stability and security in fastening applications.
Implementation Method 1
a crest of the internal thread is contacted with the outside helical surface until interference fitting
Data Source
AI summary
A connection structure for tapered male screw and threaded hole comprises a male screw and a female screw, and the male screw comprises an external helical surface and an end helical surface. The shape of the external helical surface is the same shape as a helical external surface of a rotating body formed by taking a right angle side of a right trapezoid coincident with a central axis of a cylindrical body as an axis of rotation and rotating the rotating body circumferentially at a constant speed, and at the same time moving the right trapezoid at a constant speed along the central axis of the cylindrical body. The shape of the end helical surface is the same as the helical end surface at the end in the movement direction of the axial movement of the rotating body.