Resistance Welding Fastener for Aluminum-Steel Joining
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Solution Overview
Problem
Existing methods for joining aluminum to other materials, such as steel, face challenges due to the formation of intermetallic compounds, which affect mechanical strength and corrosion resistance. Current techniques like self-pierce riveting and friction stir spot welding have limitations in terms of cycle time, alignment requirements, and joint strength.
Innovation Solution
A resistance welding fastener system that includes a welding electrode tip with a specific geometry, allowing for the application of a resistance welding fastener to a structure. The tip has a first end, a second end opposite the first end, and portions with different diameters, enabling efficient welding of dissimilar metals by minimizing intermetallic formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If self-pierce riveting is used to join high strength aluminum to steel, then joint strength is improved, but the aluminum can crack during the riveting process
Solution Approach 1:
The patent introduces a resistance welding fastener as an intermediary component that mediates the joining process between aluminum and steel. The fastener is inserted through the aluminum layer and then resistance welded to the steel substrate, avoiding direct mechanical piercing of the aluminum that causes cracking, while still achieving strong joint formation
2Object-affected harmful factors
If friction stir spot welding is used to join aluminum to steel, then intermetallic formation is reduced, but cycle time increases to 7-9 seconds for 5-6 mm joint stack-up
Solution Approach 1:
The patent replaces the mechanical friction-based joining system with an electrical resistance welding system. Instead of using mechanical friction and stirring to join the materials, the invention uses electrical current to generate heat and fuse the fastener to the steel substrate, dramatically reducing cycle time while maintaining low intermetallic formation
3Strength
If conventional through-hole riveting is used to join aluminum to steel, then joint strength is maintained with adhesive, but device complexity increases due to multiple components
Solution Approach 1:
The patent merges the fastener and welding electrode into a single integrated resistance welding fastener component. This eliminates the need for separate adhesives, barrier layers, and multiple fastener components, reducing device complexity while maintaining joint strength through the resistance welding process
4Strength
If friction bit joining is used to weld fastener to steel, then joint strength is improved, but very precise alignment and fit-up are required
Solution Approach 1:
The patent inverts the traditional approach by having the fastener inserted through the aluminum layer first, and then the resistance welding process is applied to fuse the fastener to the steel substrate. This reversal of the joining sequence eliminates the need for precise alignment and fit-up during the joining process, as the fastener is already positioned through the aluminum before welding occurs
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 system effectively joins aluminum and steel layers with improved mechanical strength and corrosion resistance, reducing cycle times and alignment complexities compared to existing methods. It allows for single-sided welding and is compatible with conventional resistance spot welding equipment.
Implementation Method 1
resistance welding fastener system that includes a welding electrode tip with a specific geometry, allowing for the application of a resistance welding fastener to a structure
Data Source
AI summary
An apparatus and method for fastening dissimilar materials like steel, plastic and aluminum. A resistance welding fastener having multiple layers may be used with or without a sealant. The fastener may be used to form an aluminum covered steel laminate via a hemming pattern of attachment. The fastener may have a solid shaft or have an extended reach and have features for interacting with the welding electrode. A variety of electrode tips may be employed to cooperate with the fastener.