Screw Reverse Prevention Mechanism Using Conic Step Structure
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Solution Overview
Problem
Conventional screws lack a reverse rotation mechanism, making them easily removable from workpieces, which is undesirable in certain applications.
Innovation Solution
A screw structure with a conic section featuring a reverse prevention mechanism, comprising at least one step structure, that prevents the screw from being unscrewed by providing a blocking and resisting effect when attempting to remove it from a workpiece.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional screw structure is used, then the screw can be easily installed and removed, but the screw can be readily screwed out and loosened, lacking reverse rotation prevention
Solution Approach 1:
The screw cap is segmented into a cylindrical section and a conic section, with the reverse prevention mechanism specifically located on the conic section. This segmentation allows the reverse prevention function to be isolated to a specific region without complicating the entire screw structure.
Solution Approach 2:
The reverse prevention mechanism is implemented locally on the conic section of the screw cap rather than throughout the entire screw. The step structures are positioned specifically where they interact with the workpiece surface to prevent reverse rotation, providing localized functionality without global complexity.
2Reliability
If a reverse prevention mechanism is added to the screw, then the reverse rotation preventing effect is enhanced, but the screw structure becomes more complex
Solution Approach 1:
Instead of preventing reverse rotation through friction or deformation as in conventional solutions, this invention uses step structures that physically block reverse rotation by engaging with the workpiece surface. The mechanism works by inversion of the conventional approach - using geometric blocking rather than force-based prevention.
Solution Approach 2:
The reverse prevention mechanism utilizes the conic section's geometric dimension, where step structures extend radially from the axis. When the screw is rotated clockwise, these steps ride over the workpiece surface; when attempted to rotate counter-clockwise, the steps are blocked by the workpiece surface, providing prevention in the reverse rotation dimension.
3Reliability
If the screw cap is extended downward to form a conic section with step structures, then the blocking and resisting effect is provided, but the manufacturing complexity increases
Solution Approach 1:
The conic section is defined by simple geometric parameters (cone angle, height, and step structure dimensions) that can be directly specified in CAD models and manufactured using standard CNC machining or molding processes. The step structures are formed as simple radial features that do not require complex tooling or multi-step manufacturing operations.
Data Source
AI summary
A screw includes a screw cap and a shank extending downward from the screw cap. The shank has an outer circumferential surface on which a thread is formed. The shank has a lower end forming a tip section. The screw cap is extended downward to form a conic section. The conic section is provided thereon with a reverse prevention mechanism, which is constructed to include at least one step structure. After the screw is screwed into a workpiece, in an attempt to screw the screw out of the workpiece, the reverse prevention mechanism providing a blocking and resisting effect to prevent the screw from being readily screwed out of the workpiece and thus, a reverse prevention effect of the screw can be enhanced to thereby improve overall performance of use of the screw.