Cathodic Arc Cleaning for Uniform Weld Oxide Removal
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Solution Overview
Problem
Current methods for removing thermal oxide layers from welds and heat-affected zones are inefficient, often incomplete, and pose safety and environmental hazards due to the use of aggressive chemicals, while mechanical methods may not ensure uniform removal.
Innovation Solution
A cathodic cleaning method using an electric arc between a non-consumable electrode and the workpiece, with an AC circuit providing minimal anodic energy for weld penetration and maximal cathodic energy for oxide removal, aided by an inert processing gas to control heat and energy distribution, effectively vaporizing the oxide layer without chemical use.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If mechanical treatments (brushing or grinding) are used to remove oxide layers, then some oxide removal is achieved, but the oxide layer cannot be removed completely or evenly and corrosion resistance is reduced due to contamination
Solution Approach 1:
The patent replaces mechanical treatment methods (brushing, grinding) with an electrochemical cleaning process using cathodic polarization and electric arc. This substitution eliminates mechanical contact that causes contamination and uneven removal, achieving complete and uniform oxide layer removal while preserving the workpiece surface integrity and corrosion resistance.
Solution Approach 2:
The patent changes the fundamental parameter of the cleaning process from mechanical force to electrochemical reaction. By applying cathodic polarization and electric arc, the cleaning mechanism transitions from physical abrasion to electrochemical dissolution, enabling precise control over oxide removal depth and uniformity while avoiding surface contamination.
2Manufacturing precision
If wet-chemical pickling with acid solutions is used, then oxide layer removal performance is excellent, but the process requires complicated safety measures and post-treatment, making it expensive and energy-consuming
Solution Approach 1:
The patent replaces wet-chemical pickling with an electrochemical cleaning process using cathodic polarization and electric arc in a non-aqueous electrolyte. This substitution eliminates the need for aggressive acids and associated safety infrastructure while maintaining excellent oxide removal effectiveness, simplifying the overall process and reducing costs.
Solution Approach 2:
The patent uses a non-aqueous electrolyte (such as organic solvents or molten salts) instead of water-based acid solutions. This creates a chemically inert environment that eliminates hazards associated with aggressive acids, removes the need for complex safety measures and post-treatment rinsing, while still achieving effective oxide layer removal through electrochemical reactions.
3Strength
If conventional DC welding polarity is used, then weld penetration is achieved, but excessive heat is generated on the workpiece causing unwanted thermal effects
Solution Approach 1:
The patent inverts the conventional DC welding polarity by using reverse polarity (RP) where the electrode is connected to the positive terminal and the workpiece to the negative terminal. This inversion shifts the heat generation from the workpiece to the electrode, maintaining adequate weld penetration while significantly reducing unwanted thermal effects on the workpiece such as heat-affected zone formation and thermal distortion.
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 method provides a safe, efficient, and flexible means to remove oxide layers completely and uniformly, enhancing corrosion resistance and weld quality without the need for hazardous chemicals, allowing for independent control of cleaning depth and heat management.
Implementation Method 1
a cleaning method for removing thermal oxide which is formed on a surface of a workpiece during a previous joining process, wherein an electric arc is generated between the joined workpiece and a non-consumable electrode to remove the oxide on the workpiece
Implementation Method 2
an electric arc is generated between the joined workpiece and a non-consumable electrode to remove the oxide on the workpiece
Data Source
Figure 1~2
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AI summary
A method of cleaning a workpiece (6, 8, 9) after a welding process is provided, wherein the cleaning is conducted by removing oxide from the surface of the workpiece (6, 8, 9) which is formed on the weld (8) and the heat-affected zone (9) of the workpiece (6) during the previous welding process, wherein an electric arc is generated between the workpiece (6, 8, 9) and a non-consumable electrode (2) to remove the oxide on the workpiece (6, 8, 9), wherein a power source (7) is provided to electrically communicate the workpiece (6, 8, 9) and the non-consumable electrode (2) and wherein the non- consumable electrode (2) is anodic connected and the workpiece (6, 8, 9) is cathodic connected.