Clearance-Hole Self-Piercing Riveting for Hard Material Stacks
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Solution Overview
Problem
Self-piercing riveting technologies face challenges with hard materials, leading to rivet fracture or buckling, substrate damage, and corrosion concerns due to galvanic potential, particularly in mixed metal and composite applications, limiting the use of mixed materials and ultra-high strength materials in automotive manufacturing.
Innovation Solution
Forming a clearance hole in one or more layers before riveting to avoid deformation and damage, allowing the rivet to interlock without piercing the substrate, thereby minimizing fiber delamination and corrosion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If self-piercing riveting is used with hard materials, then joining capability is achieved, but rivet fracture or buckling occurs
Solution Approach 1:
A clearance hole is formed in the substrate before the riveting process. This preliminary action removes the obstruction that would otherwise cause rivet fracture or buckling, allowing the rivet to be set without piercing the substrate and thereby preventing damage to the rivet while maintaining joining capability.
2Strength
If self-piercing riveting is used with hard materials, then joining capability is achieved, but substrate damage occurs
Solution Approach 1:
A clearance hole is formed in the substrate before the riveting process. This preliminary action eliminates the need for the rivet to pierce the substrate, thereby preventing fiber delamination and other substrate damage while still achieving secure joining through the clearance hole.
3Adaptability or versatility
If mixed metal materials are joined, then material versatility is improved, but corrosion concerns increase due to galvanic potential
Solution Approach 1:
A clearance hole is formed in one of the layers before riveting. This allows the rivet to be inserted without piercing through both layers, reducing the exposure of dissimilar metals to each other and thereby minimizing galvanic corrosion potential while still achieving secure joining of mixed metal materials.
Data Source
AI summary
A system for attaching layers of material together comprised of a self-piercing rivet, a layer having a clearance hole through which the self-piercing rivet passes on assembly, and a layer free of a clearance hole and into which the self-piercing rivet is at least partially inserted. The system may include a third layer free of a clearance hole. The system may also include three layers wherein the clearance hole is formed in the middle layer. If the clearance hole is formed in the middle layer, the width of the hole may be greater than the diameter of the self-piercing rivet to avoid contact between the rivet and the middle layer. The layer having the clearance hole may be a hard material such as steel. One or more of the layers may be material that is difficult to pierce or can be damaged if pierced.