Laser-Welded Joint Structure for Dissimilar Metal Joining
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Solution Overview
Problem
Conventional methods for joining dissimilar materials, such as spot welding and rivet-based techniques, are inefficient and costly due to the need for precise machining, long processing times, and restricted design flexibility, especially when trying to join materials like steel and aluminum.
Innovation Solution
A joint structure that uses laser welding with a similar metal material and a dissimilar material sandwiched between them, featuring a through opening portion with protrusions and carefully controlled gaps to facilitate reliable fusion and increased rigidity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If spot welding is used to join dissimilar materials, then joining strength is improved, but production time increases due to compression, current application, and cooling requirements
Solution Approach 1:
The patent replaces the mechanical compression and electrical current application system of spot welding with a laser-based thermal welding system. The laser beam directly heats and melts the materials to form a weld, eliminating the need for mechanical compression electrodes and prolonged cooling periods, thereby significantly reducing production time while maintaining joining strength
Solution Approach 2:
The patent changes the welding parameters by using laser beam intensity and duration control instead of mechanical pressure and electrical current parameters. By adjusting laser power, scanning speed, and focal position, the process achieves efficient welding of dissimilar materials with reduced cycle time compared to conventional spot welding
2Reliability
If rivet-based joining is used for dissimilar materials, then joining reliability is improved, but manufacturing complexity increases due to precise machining requirements
Solution Approach 1:
The patent replaces the mechanical rivet insertion and deformation system with laser welding. Instead of requiring precisely machined rivet holes and complex rivet geometries, the laser beam directly fuses the materials, simplifying the manufacturing process while maintaining or improving joining reliability through controlled thermal processing
Solution Approach 2:
The patent introduces a filler material as an intermediary between dissimilar materials that are difficult to weld directly. This filler material facilitates the welding process by improving material compatibility and weld pool fluidity, enabling reliable joints without complex pre-machining or specialized rivet designs
3Ease of operation
If adhesive joining is used for dissimilar materials, then ease of operation is improved, but joining strength deteriorates compared to mechanical joining methods
Solution Approach 1:
The patent replaces adhesive bonding with direct laser welding or friction stir welding, which creates metallurgical or mechanical interlocking joints. These welding methods produce joints with strength comparable to or exceeding the base materials, eliminating the strength limitations of adhesive bonding while maintaining operational simplicity through automated laser or mechanical welding processes
4Strength
If conventional spot welding guns are used, then joining capability is improved, but device weight increases and moving speed decreases
Solution Approach 1:
The patent replaces heavy mechanical spot welding guns with a laser welding system. The laser beam can be rapidly positioned and directed by computer-controlled mirrors or galvanometers, achieving much higher moving speeds and positioning accuracy. This eliminates the inertia and mechanical complexity of traditional welding guns while maintaining effective joining capability
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 enables highly reliable dissimilar material joining with reduced production time, increased rigidity, and enhanced design flexibility, improving productivity and reducing manufacturing costs.
Implementation Method 1
a first gap is provided between the protrusion and an inner peripheral surface of the through opening portion. In addition, a second gap is provided between the first material and the second material... the first material and the second material welded via the through opening portion
Implementation Method 2
weld materials need to be pressed with upper and lower electrodes, which are spot welding guns for performing spot welding, to eliminate the gap between the weld materials
Data Source
AI summary
A joint structure includes a first material (1), a second material (2) weldable to the first material, and a third material (3) at least a portion of which being sandwiched between the first material and the second material, having a through opening portion at the sandwiched portion, and including a material that is difficult to be welded to both the first material and the second material, the first material and the second material welded the via through opening portion. At least one of the first material and the second material is provided with a protrusion (14) inserted in the through opening portion. A first gap (4) is provided between an inner peripheral surface of the through opening portion and the protrusion. A second gap (5) is provided between the first material and the second material, the second gap having a size depending on a plate thickness of the first material in a region corresponding to the protrusion. Under a condition in which the second gap has a size of greater than or equal to 0.1 mm but less than or equal to 40% of the plate thickness of the first material in the region, the first material and the second material are welded by emitting a laser beam from a side on which the first material is disposed.