Spot-Welded Joint Indentation Structure for Crack-Resistant Aluminum Welding
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Solution Overview
Problem
Existing resistance spot welding technologies for aluminum alloys face challenges such as high manufacturing costs, severe spatter and internal defects, surface cracks, poor surface quality, and short electrode life due to high electrical conductivity and thermal conductivity, as well as the presence of a high resistance oxide film.
Innovation Solution
A spot-welded joint design featuring a central indentation with a convex first surface and a concave second surface, along with a pancake-shaped weld nugget and multi-stage pulse welding, reduces heat concentration and enhances electrode life by promoting uniform heat distribution and stress distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ordinary spot welding technology is used for aluminum alloys, then welding can be achieved, but severe spatter and internal defects occur along with surface cracks
Solution Approach 1:
The electrode surface is designed with different local structures: a convex center portion and a concave peripheral portion with annular ridges. This local quality differentiation directs heat concentration to the center for proper nugget formation while the peripheral structure controls oxide film removal and heat distribution, preventing spatter and surface cracks
Solution Approach 2:
The electrode surface geometry is pre-configured before welding to control the welding process. The convex center and concave periphery with annular ridges are formed in advance on the electrode, enabling preliminary control of heat distribution and oxide film removal patterns during welding
2Strength
If high current and high electrode pressure are used to weld aluminum alloys, then welding can be achieved, but manufacturing costs increase
Solution Approach 1:
The electrode surface geometry parameters are changed from a conventional smooth surface to a structured surface with convex center and concave periphery. This parameter change modifies the electrical and thermal field distribution, enabling effective welding at lower current and pressure levels while maintaining weld strength
Solution Approach 2:
Different regions of the electrode surface have different properties: the convex center concentrates current density for nugget formation while the concave periphery with annular ridges distributes heat and removes oxide films. This local quality differentiation improves welding efficiency and reduces overall energy consumption
3Productivity
If conventional electrodes are used for spot welding aluminum alloys, then welding can be performed, but electrode life is short due to high resistance oxide film
Solution Approach 1:
The electrode surface is pre-structured with convex center and concave periphery before welding begins. This preliminary structural configuration enables the electrode to effectively manage oxide film removal and heat distribution from the first weld, preventing premature electrode degradation
Solution Approach 2:
The electrode surface has differentiated local structures: the convex center maintains good contact for stable electrical connection while the concave periphery with annular ridges facilitates oxide film removal. This local quality differentiation protects the electrode from uniform wear, extending its service life
4Reliability
If welding heat is concentrated in the center of the welded joint, then welding can be achieved, but cracks form on the surface and welded joint strength decreases
Solution Approach 1:
The electrode surface structure creates localized heat concentration at the center through the convex portion while the concave periphery with annular ridges provides controlled heat distribution. This local quality differentiation in heat distribution prevents excessive center heat concentration, reducing surface cracks while maintaining welded joint strength
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 solution results in improved weld strength, reduced defects, enhanced surface quality, and extended electrode life, while minimizing energy consumption and manufacturing costs.
Implementation Method 1
Resistance spot welding uses the heat generated by the resistance of the workpiece itself and between them to melt the material and achieve connection
Data Source
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AI summary
A spot-welded joint and a manufacturing method therefor. The spot-welded joint comprises a first workpiece (1), a second workpiece (2), and a weld nugget used for fixedly connecting the first workpiece (1) and the second workpiece (2). At least one of the outer surface of the first workpiece (1) and the outer surface of the second workpiece (2) comprises a basic surface and an indentation, wherein the indentation comprises a first surface (111) which is located in the center and protrudes outwards and a second surface (112) which is located on the periphery of the first surface (111) and recessed inwardly, and the maximum distance hl between the first surface (111) and the basic surface is smaller than the maximum distance h2 between the second surface (112) and the basic surface. The edge welding of the spot-welded joint is firmer, and the center is thinner, so that the generation of surface cracks and the formation of internal defects are reduced, thereby improving the welding spot strength.