Self-Attaching Nut With Radial Ribs and Transverse Grooves
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Solution Overview
Problem
Existing self-attaching female fasteners, such as pierce and clinch nuts formed by cold header techniques, lack sufficient torque resistance and efficient interconnection methods, particularly when using frangible wires for continuous installation in a die press.
Innovation Solution
The self-attaching nut design features a central pilot portion with a bore and a flange portion having a V-shaped annular groove and circumferentially spaced radial ribs, which provide enhanced torque resistance, and includes transverse parallel grooves for easy alignment and interconnection with frangible wires, allowing for improved resistance to rotation and ease of installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional self-attaching nuts with round or polygonal flange portions are used, then they can be manufactured by cold header techniques, but they require precise alignment during installation and lack sufficient torque resistance
Solution Approach 1:
The flange portion is designed with an asymmetric configuration featuring transverse parallel grooves that accept frangible wires, eliminating the need for precise alignment during installation. This asymmetric design allows the nuts to be interconnected in a linear array without requiring orientation matching, directly resolving the alignment requirement issue while maintaining torque resistance through the rib structure
Solution Approach 2:
The flange portion is segmented into distinct functional zones: a substantially V-shaped annular groove for deformation and securing, radial ribs for torque resistance, and transverse parallel grooves for wire interconnection. This segmentation allows each feature to independently contribute to its specific function, achieving both torque resistance and ease of installation
2Reliability
If radial ribs are positioned close to the pilot portion outer surface, then torque resistance is improved, but the structural integrity and wire interconnection capability are compromised
Solution Approach 1:
The radial ribs are positioned on the panel support surface rather than extending to the pilot portion outer surface, creating spatial separation between the torque-resistance function and the wire interconnection function. This dimensional arrangement allows frangible wires to pass through the flange portion without interfering with the ribs, while the ribs remain effective at preventing rotation
Solution Approach 2:
Different regions of the flange portion are assigned different functional qualities: the V-shaped annular groove provides deformation and securing, the radial ribs provide torque resistance, and the transverse parallel grooves provide wire interconnection pathways. This local differentiation allows each region to optimize its specific function without compromising overall performance
3Productivity
If frangible wires are used for interconnecting nuts, then continuous installation is enabled, but alignment of polygonal or rectangular nuts is difficult
Solution Approach 1:
The flange portion is designed with universal interconnection features (transverse parallel grooves) that work with any nut orientation, making the alignment process unnecessary. The frangible wires can be inserted through the grooves regardless of how the nuts are oriented, enabling continuous installation without the alignment difficulties associated with polygonal or rectangular nuts
Data Source
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AI summary
A self-attaching nut for attachment to a panel including a central pilot portion having a generally cylindrical outer surface, a flange portion surrounding the outer surface of the pilot portion including an annular groove surrounding the pilot portion having a substantially V-shaped bottom wall and a generally planar panel support surface surrounding the annular groove. The panel support surface includes a plurality of circumferentially spaced radial ribs extending into the annular groove, but spaced from the outer surface of the pilot portion. The grooves may be convex or concave or a combination of convex and concave grooves. In one embodiment, the nuts are rectangular and the back face include two pair of transverse linear grooves for interconnection by frangible wires in side to side relation.