Welded Rivet Joining of Aluminum to Steel With a Flush Surface
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Solution Overview
Problem
Conventional riveting processes fail to effectively join aluminum components to steel components with high tensile strength, such as Al—Si coated press hardened steel and advanced high strength steel, due to protrusions that obstruct assembly and dimensional geometry issues in applications like door flange mounting areas.
Innovation Solution
A method involving a weld tool with an electrode and arms to arrange a carbon-coated steel rivet in a cavity of an aluminum component, applying pressure and current to weld the rivet, ensuring the rivet is flush with the aluminum surface by matching its volume to the cavity volume, and using a resistance-reducing coating on the rivet head to optimize heat generation and bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional riveting processes are used to join aluminum component to steel component, then the components can be connected, but protrusions are created above the aluminum component that obstruct assembly and are unacceptable in mounting areas
Solution Approach 1:
A cavity is formed in the aluminum component at the rivet location before rivet installation. This preliminary action creates a recess that accommodates the rivet head and material deformation during welding, ensuring the rivet remains flush with or below the aluminum component surface after joining, thus eliminating protrusions that would obstruct assembly
Solution Approach 2:
The invention changes the physical state and volume parameters of the rivet material through controlled welding. By applying heat and pressure, the rivet material undergoes phase changes and volume reduction, allowing it to be embedded within the cavity and achieve a flush surface finish while maintaining strong joint strength
2Shape
If structural adhesive is used to join aluminum component to steel component, then no protrusions are created, but the aluminum component must be held in position through the paint shop to ensure dimensional geometry during curing
Solution Approach 1:
The invention replaces the mechanical positioning and holding system required for adhesive curing with a welding process. The weld tool with electrode and arms provides precise positioning and applies localized heat and pressure to join the rivet, eliminating the need for complex fixtures to maintain dimensional geometry throughout the paint shop process
Solution Approach 2:
The cavity is prepared in advance in the aluminum component, and the rivet is positioned before welding. This preliminary preparation ensures proper alignment and dimensional geometry are achieved before the welding process begins, eliminating the need for prolonged positioning and holding during curing as required with adhesives
3Shape
If the rivet volume above the cavity is too large, then protrusions are created that obstruct assembly, but if the rivet volume is reduced, then joint strength may be compromised
Solution Approach 1:
The welding process applies controlled heat and pressure to change the volume and density parameters of the rivet material. This allows the rivet to be compressed and embedded within the cavity, achieving a flush surface finish while maintaining sufficient material volume and structural integrity for strong joint strength
Solution Approach 2:
The cavity is designed with specific volume and dimensions before rivet installation. This preliminary design ensures that when the rivet is welded and compressed, it will achieve the optimal balance between surface flushness (no protrusions) and joint strength, as the cavity volume is calculated to accommodate the rivet material after welding-induced volume reduction
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 method achieves a strong, flush weld between aluminum and steel components, preventing protrusions and ensuring proper assembly, while maintaining the structural integrity of high-strength steel materials.
Implementation Method 1
applying current to the electrode to weld the rivet in the cavity
Implementation Method 2
The rivet includes a coating on a head of the rivet in contact with the electrode of the weld tool, wherein the coating reduces a resistance between the electrode and the head of the rivet
Data Source
AI summary
A method for welding includes arranging an aluminum component including a cavity adjacent to a steel component; and using a weld tool including an electrode and arms configured to engage a rivet, arranging the rivet in the cavity in contact with the steel component. A volume of a portion of the rivet located above of the cavity is approximately equal to an annular volume between a stem of the rivet and an inner surface of the cavity. The method includes applying pressure on the rivet using the electrode; and applying current to the electrode to weld the rivet in the cavity.