Gas-Tight Sheet Metal Fastener With Internal Anti-Rotation Notches
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Solution Overview
Problem
Existing functional elements for attaching to sheet metal parts lack a fluid-tight connection and sufficient torsion resistance, especially when designed for single-sheet metal applications without perforations.
Innovation Solution
A functional element with a flange and a hollow cylindrical section that protrudes from the flange, featuring notches on both the inner and outer lateral surfaces, which provide enhanced anti-rotation properties and a diverging truncated cone shape for widening during stamping, ensuring a secure and leak-tight attachment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If anti-rotation ribs are provided on the outer surface of the hollow cylindrical section, then the functional element can be produced inexpensively, but the torsion resistance is insufficient
Solution Approach 1:
The patent inverts the conventional approach by moving the anti-rotation features from the outer surface to the inner surface of the hollow cylindrical section. The notches are now provided on the inner lateral surface instead of outer ribs, which surprisingly increases torsion resistance by at least 20% while maintaining manufacturability
Solution Approach 2:
The hollow cylindrical section with notches on its inner surface creates a porous-like structure that enhances mechanical interlocking with the sheet metal component. The notches allow sheet metal material to engage with the inner surface, significantly improving anti-rotation and torsion resistance
2Strength
If a punch rivet is used to connect two sheet metal parts, then fastening function is achieved, but fluid-tight connection is not possible
Solution Approach 1:
The patent extracts the punching function by designing the hollow cylindrical section to be stamped into a single sheet metal part without perforating it. The section is received in a thickening of the sheet metal in a form-fitting manner, eliminating the need for holes while maintaining fastening strength and enabling fluid-tight connection
Solution Approach 2:
The hollow cylindrical section acts as a flexible element that can be deformed during the stamping process to create a form-fitting connection within the thickening of the sheet metal, ensuring both mechanical strength and fluid-tight sealing
3Strength
If the hollow cylindrical section is widened during stamping, then secure attachment is achieved, but the section must maintain structural integrity
Solution Approach 1:
The patent applies local quality by providing the diverging truncated cone shape only in a specific area immediately adjacent to the free end of the hollow cylindrical section. This localized geometry change enables the section to widen during stamping for secure attachment while maintaining structural integrity in the remaining portions of the cylinder
Data Source
Figure 1A~1B
Figure 1C~1E
Figure 2A~2B
AI summary
A functional element (10) is provided with a section (16) which has a flange (12) and protrudes from one side (14) of the flange (12) and is designed for punching into a sheet metal part without any perforations, and a section (16) from one of the first sides (14) opposite side (18) of the flange (12) protruding and fulfilling a function shank part (20) provided with a longitudinal axis (22). The flange (12) and the section (16) are arranged at least essentially coaxially with the shaft part (20). The section (16) is designed as a hollow cylinder which has notches (26) extending parallel to the longitudinal direction on at least one of its outer lateral surface (24) and its inner lateral surface (52). On the inside (50) of the section (16) in the area of its free front end (28), the section (16) has a diverging truncated cone shape that tapers out at least essentially at the free end (28), which when stamped into the sheet metal part causes the widening of the section (16) serves. An assembly component and a method for its manufacture are also claimed.