Grooved Spot-Welding Electrode for Oxide Film Contact Stability
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Solution Overview
Problem
The challenge in spot welding aluminum alloy sheets lies in the instability caused by surface oxide films, which block current flow and result in uneven nugget formation, and the need for specialized tip dressers to maintain electrode shape during cleaning.
Innovation Solution
A welding electrode with elongated grooves or blind holes on its end face, where the depth is between 0.5 mm and 20 mm, and the depth-to-width ratio is 2 or more, allowing for effective penetration of the oxide film and stable contact with the workpiece, enabling efficient current flow and stable nugget formation without requiring specialized dressers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a convex portion is provided on the welding electrode end face to penetrate the oxide film, then electrical resistance is reduced and current flow is improved, but a special tip dresser is required and general tip dressers cannot be used
Solution Approach 1:
The end face of the welding electrode is segmented into multiple grooves or blind holes instead of using a single convex portion. This segmentation allows the oxide film penetration function to be distributed across multiple features, maintaining electrical contact stability while enabling the use of general tip dressers that can accommodate various groove patterns.
Solution Approach 2:
Instead of adding a convex portion that protrudes outward to penetrate the oxide film, the invention inverts the approach by creating grooves or blind holes that extend inward into the electrode end face. The oxide film is penetrated through the edges of these grooves/holes rather than by a central凸起, allowing general dressers to effectively maintain the electrode surface.
2Reliability
If the end face of the welding electrode is shaved using a tip dresser to remove contamination, then electrical resistance is reduced, but the shape of the convex portion may change and welding characteristics are altered
Solution Approach 1:
The grooves and blind holes are designed with sufficient depth (0.5-20 mm) and aspect ratio (d/w ≥ 2) to provide a cushion that protects the essential oxide film penetration geometry during the dressing process. Even when the end face is shaved, the grooves/holes maintain their depth and shape characteristics, ensuring consistent welding performance after maintenance.
Solution Approach 2:
The end face structure resembles a porous configuration with multiple grooves or blind holes that provide redundant pathways for oxide film penetration. This porous-like structure ensures that even if some features are modified during dressing, sufficient functional features remain to maintain stable electrical contact and welding characteristics.
3Reliability
If a large current is applied to overcome the oxide film resistance, then nugget formation is improved, but heat generation at the electrode-workpiece boundary increases and adhesion occurs
Solution Approach 1:
The grooves and blind holes create localized regions of reduced electrical resistance at specific points on the end face. Instead of requiring uniformly high current across the entire contact surface, the oxide film penetration occurs at the groove/hole edges where resistance is locally reduced, allowing current concentration in beneficial areas while suppressing harmful heat generation at the overall boundary.
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 design ensures stable welding quality by reducing electrical resistance, increasing current density, suppressing heat generation, and maintaining the electrode's shape during dressing, allowing for consistent large nugget formation even after maintenance.
Implementation Method 1
spot welding is a welding method that utilizes resistance heat generated by applying a large current to the welding point
Implementation Method 2
a portion where the metal of the workpiece and the welding electrode are in direct contact without intervention of the surface oxide film can be formed. This reduces the electrical resistance at the boundary between the welding electrode and the workpiece
Data Source
AI summary
The present invention provides a welding electrode capable of spot-welding a workpiece having a surface oxide film with stable welding quality, the welding electrode allowing general tip dressers to be used. The welding electrode of the present invention is used for spot welding of a workpiece. The welding electrode includes an end face provided so as to contact the workpiece, and at least one elongated groove provided in the end face or a plurality of blind holes provided in the end face. A depth of the groove or a depth of the blind holes is 0.5 mm or more and 20 mm or less. A ratio (d/w) of the depth d of the groove to a width w of the groove or a ratio (d/s) of the depth d of the blind holes to a size s of the blind holes is 2 or more.