Self-Tapping Screw Joint Structure to Prevent Plate Gaps
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Solution Overview
Problem
The existing methods for joining metal plates using self-tapping screws often result in gaps between the plates, which compromise dimension accuracy and can lead to deterioration in water cut-off performance and backlash, especially when excess material from one plate enters the gap between the top and bottom plates during screwing.
Innovation Solution
A joining method that involves forming recessed portions in the plates to accommodate the self-tapping screw, ensuring that any excess material generated during screwing flows into these recessed areas rather than forming a gap between the plates, thereby preventing the formation of gaps and maintaining the integrity of the water cut-off performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a self-tapping screw penetrates through the top plate to join the top plate and bottom plate, then the joining strength is improved, but an excess part generated from the top plate enters between the top plate and bottom plate, forming a gap that deteriorates dimension accuracy
Solution Approach 1:
A through-hole is formed in the top plate before joining to allow excess material to escape during the screwing process, preventing gap formation between plates while maintaining joining strength
Solution Approach 2:
The excess material generated during screwing is extracted through the pre-formed through-hole rather than being forced into the gap between plates, thereby preserving dimension accuracy
2Manufacturing precision
If a through-hole larger than the self-tapping screw external-thread outside diameter is formed in the top plate to prevent excess part generation, then dimension accuracy is improved, but deterioration in water cut-off performance and backlash of the top plate might be caused
Solution Approach 1:
Instead of forming a large through-hole that compromises water cut-off performance, a recessed portion is formed locally at the screw penetration point to accommodate excess material, thereby maintaining both dimension accuracy and water cut-off performance
Solution Approach 2:
The excess material generated during screwing, which normally causes gaps, is redirected to fill the recessed portion, converting a harmful effect into a beneficial one that improves joining appearance and dimension accuracy without compromising water cut-off performance
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
In a joining method for joining a first plate material (11) and a second plate material (12) by screwing a self-tapping screw (100) from one direction in a state where the first plate material (11) and the second plate material (12) are put on top of each other, a recessed portion (11a) is formed in at least one of the first plate material (11) and the second plate material (12), and in a state where the first plate material (11) and the second plate material (12) are put on top of each other such that the recessed portion (11a) is opened in a contacting face (Fll) between the first plate material (11) and the second plate material (12), the self-tapping screw (100) is screwed from the one direction. When the self-tapping screw (100) penetrates through the first plate material (11) due to the screwing of the self-tapping screw (100), an excess part (M) generated from the first plate material (11) flows into the recessed portion (11a).