Wing-Shaped Thrust Screw Assembly for Over-Screwing Stop Control
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Solution Overview
Problem
Conventional screws lack a mechanism to prevent further screwing motion once a preset distance is reached, leading to potential damage or improper locking, and existing solutions are costly and complex in fabrication.
Innovation Solution
A wing-shaped thrust screw assembly with a thrust member featuring two wing-shaped stop pieces and flat portions, which are formed integrally with the screw using threading dies, stopping further screwing motion by having an outer diameter greater than the external thread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional self-tapping screw is used, then the screw can be easily manufactured and installed, but it lacks a mechanism to prevent further screwing motion once a preset distance is reached
Solution Approach 1:
The screw shaft is divided into multiple functional sections: a head section, a first shank with external threads, a second shank with a thrust member, and a drilling member. This segmentation allows each section to perform its specific function - the external threads engage the workpiece, the thrust member prevents over-screwing, and the drilling member creates the hole, thereby achieving reliable screwing motion control without excessive overall complexity.
Solution Approach 2:
The thrust member is designed with a diameter larger than the external threads, creating a dynamic stop mechanism. As the screw is driven into the workpiece, the thrust member naturally limits the penetration depth by contacting the workpiece surface, providing automatic screwing motion control without requiring complex external devices.
2Reliability
If separate wall anchor and headless screw components are used to achieve thrust function, then the screwing motion can be controlled, but the fabrication process becomes complicated and costly
Solution Approach 1:
The invention merges the thrust member and external threads into a single integrated screw assembly. The thrust member is formed on the second shank of the same screw body that carries the external threads on the first shank, eliminating the need for separate wall anchor and headless screw components. This integration simplifies the fabrication process to a single molding operation while maintaining reliable thrust function.
Solution Approach 2:
The single screw assembly performs multiple functions: the drilling member creates the hole, the external threads on the first shank engage the workpiece for fastening, and the thrust member on the second shank prevents over-screwing. This multi-functionality in one component replaces the need for multiple separate parts, simplifying both manufacturing and assembly.
3Reliability
If the thrust member is formed by extrusion with a stop ring and washer, then the screwing motion can be stopped, but the stop ring easily passes through the perforation and becomes deformed or broken
Solution Approach 1:
The thrust member is segmented into two functional parts: the external threads on the first shank for fastening and the thrust member on the second shank for depth control. This segmentation allows the thrust member to be optimized specifically for its stopping function without compromising the fastening function, improving overall reliability and durability.
Solution Approach 2:
The thrust member is designed with a diameter larger than the external threads, creating a natural mechanical stop. As the screw is driven into the workpiece, the thrust member contacts the workpiece surface and prevents further penetration, providing reliable and durable screwing motion stopping without the weaknesses of previous stop ring designs.
Data Source
AI summary
A thrust screw assembly includes a thrust screw and two threading dies for working the thrust screw. The thrust screw includes a first shank, a second shank, an external thread, and a thrust member. Each of the threading dies is provided with an external thread forming section and a flat portion forming section. In a first molding process, the first shank is worked to form the thrust member with two wing-shaped stop pieces. In a second molding process, the second shank is processed by the external thread forming section of each of the two threading dies to form the external thread on the second shank, and the two wing-shaped stop pieces is processed by the flat portion forming section of each of the two threading dies to form two flat portions on the two wing-shaped stop pieces simultaneously.