Clinch Fastener Rim Structure for Leak-Resistant Panel Joining
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Solution Overview
Problem
Existing clinch fasteners struggle to provide effective leak resistance, especially in applications requiring high torque-out and water-tight capabilities, due to the geometry of the fastener and material interaction, which can lead to fluid ingress and material degradation.
Innovation Solution
A clinch fastener design featuring a displacer bead, radial undercut, and flange with a dimpled rim and concave corners, along with a rapid pressing method to create pressurized air pockets, elongating the leak path and preventing fluid ingress through capillary action.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing clinch fastener geometry is used, then mechanical performance (torque-out, push-out, pull-through) is achieved, but fluid ingress occurs through the fastener-material interface
Solution Approach 1:
The fastener body is segmented into multiple functional zones: an enlarged head portion with circumferential grooves, a reduced shank portion, and a transition zone. The grooves are further segmented into multiple circumferential grooves at different positions, creating distinct sealing zones that collectively prevent fluid ingress while maintaining structural integrity
Solution Approach 2:
The invention introduces axial dimensionality to the sealing mechanism by creating circumferential grooves at different axial positions on the fastener body. This multi-level axial segmentation creates a three-dimensional sealing path that fluid must navigate, significantly increasing the leak path length and resistance without requiring complex radial or circumferential modifications
2Reliability
If rapid pressing is used to create air pockets, then leak resistance is enhanced, but installation process complexity increases
Solution Approach 1:
The fastener geometry is pre-designed with enlarged head portion and circumferential grooves that are specifically configured to trap air during installation. This preliminary geometric configuration ensures that when rapid pressing is applied, air pockets are automatically formed in the correct locations without requiring additional tools, steps, or control mechanisms during the installation process
3Strength
If material deformation is increased to secure fastener, then mechanical attachment strength is improved, but leak path is shortened
Solution Approach 1:
The fastener design applies different deformation characteristics to different portions: the shank portion is designed for material displacement and deformation to achieve mechanical attachment strength, while the head portion with circumferential grooves is designed to maintain geometric integrity and create sealing zones. This local differentiation allows high attachment strength without compromising the leak path length in the sealing zones
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 design significantly reduces the likelihood of fluid ingress by creating a convoluted leak path and pressurized air pockets, enhancing leak resistance without the need for additional seals or welds, thus preventing material degradation.
Implementation Method 1
a rapid pressing method to create pressurized air pockets
Implementation Method 2
preventing fluid ingress through capillary action
Data Source
AI summary
A clinch fastener has material displacing features which create a lengthened leak path boundary between the fastener and an attached panel which can be a potential leak path of fluid from one side of the panel to the other. The material displacing features include a dimpled peripheral rim which displaces material of the attached panel along the perimeter of the fastener and lengthens the leak path. An increased installation pressing speed using these structures creates trapped compressed pockets of air above atmospheric pressure between the fastener and the panel providing additional leak resistance.