Dissimilar Material Joining via Resistance Spot Welding
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Solution Overview
Problem
Conventional dissimilar material joining methods require large-scale apparatus and numerous joining steps, making them inefficient for securely joining different materials using electrical energy under pressure.
Innovation Solution
A method involving a laminated structure with a first plate-shaped part and a second plate-shaped part having a higher melting point, where the first part has a concave portion and the second part has through holes for protrusions, enhancing bonding strength by electrical energizing under pressure with electrodes, and optionally including a third part with a nugget for improved reliability and heat distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pulsed electricity joining method in furnace is used, then dissimilar materials can be joined, but the joining apparatus becomes large in scale and numerous joining steps are required
Solution Approach 1:
The patent replaces the conventional furnace-based pulsed electricity joining system with a resistance spot welding apparatus. This substitution uses electrical resistance heating combined with mechanical pressure through electrodes, eliminating the need for large-scale furnace equipment while achieving reliable dissimilar material joining through localized heat generation and controlled plastic deformation.
Solution Approach 2:
The patent divides the joining process into discrete resistance spot welding operations at multiple positions. By forming protrusions and recesses that interlock across the interface, the joining is segmented into localized welding points that collectively provide strong bonding, reducing the need for continuous complex heating zones required in furnace methods.
2Reliability
If conventional pulsed electricity joining method in furnace is used, then dissimilar materials can be joined, but a large number of joining steps are required
Solution Approach 1:
The patent combines multiple joining functions into a single resistance spot welding process. The protrusion formation, material flow control, and bonding all occur simultaneously during the welding operation, eliminating the need for separate heating, shaping, and joining steps required in conventional furnace methods.
Solution Approach 2:
The patent changes the joining parameters from furnace-based pulsed electricity with complex temperature control to resistance spot welding with controlled current, pressure, and time parameters. This parameter transformation simplifies the process into fewer, more controllable steps while maintaining joining reliability through precise parameter optimization.
3Strength
If through holes and protrusions are added to enhance bonding strength, then bonding strength in rotation direction is improved, but manufacturing complexity increases
Solution Approach 1:
The patent incorporates through holes and protrusions as preliminary features in the plate design before joining. These features are pre-formed during plate fabrication, so no additional complex manufacturing steps are required during the joining process itself. The resistance spot welding simply utilizes these pre-existing features to create the interlocked bonding structure.
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
This approach effectively improves bonding strength between dissimilar materials, particularly in the direction of rotation, and reduces apparatus size and joining steps, enabling reliable joining using a joining machine with electrodes.
Implementation Method 1
obtained by subjecting to electrical energizing under pressure with electrodes and thereby joining
Implementation Method 2
the first plate-shaped part is melted and flows into interior of the through hole, and a solidification step of stopping supply of electrical energy by the electrodes with respect to the laminated member, whereby the first plate-shaped part becomes solidified and forms a protrusion inside the through hole
Data Source
AI summary
A dissimilar material joined body is obtained by subjecting to electrical energizing under pressure and joining with electrodes a laminated member, which is of a structure in which a first plate-shaped part and a second plate-shaped part having a higher melting point than that of the first plate-shaped part are superimposed on each other. A concave portion having a shape corresponding to the outer shape of an electrode is formed on the surface of the first plate-shaped part on a side thereof opposite to the second plate-shaped part. The first plate-shaped part includes protrusions, which are inserted into through holes formed in the second plate-shaped part. A method of joining dissimilar materials includes a hole forming step, a stacking step, a pressure energizing step, and a solidification step.