Long Stick-Out SAW Arc Start With DCEN-to-DCEP Switching
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Solution Overview
Problem
Conventional submerged arc welding (SAW) systems face challenges in achieving high deposition rates and consistent weld quality, particularly in deep and narrow grooves, and suffer from suboptimal arc-start performance in long stick-out (LSO) SAW processes.
Innovation Solution
Implementing a welding system that applies direct current electrode negative (DCEN) to initiate the arc and then switches to direct current electrode positive (DCEP) or alternating current (AC) to maintain a stable arc, combined with an extended stick-out length for the electrode to enhance preheating and control energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If long stick-out (LSO) electrode is used in submerged arc welding, then deposition rate is improved, but arc-start performance deteriorates
Solution Approach 1:
The welding process is divided into two distinct phases: an arc-start phase using DCEN polarity and a main welding phase using DCEP polarity. This segmentation allows optimization of each phase independently - DCEN provides reliable arc initiation, while DCEP delivers high deposition rates, thereby resolving the contradiction between arc-start performance and productivity
Solution Approach 2:
The DCEN arc-start phase serves as a preliminary action that establishes a stable arc before transitioning to the main DCEP welding phase. This preliminary arc formation ensures reliable ignition and stability, particularly important for LSO electrodes, before the high-deposition welding process begins
2Temperature
If long stick-out (LSO) electrode is used, then preheating is enhanced, but arc stability deteriorates
Solution Approach 1:
The system dynamically switches between DCEN and DCEP polarities at different phases of the welding process. During arc-start, DCEN provides stability; during main welding, DCEP provides enhanced preheating. This dynamic polarity change allows the system to achieve both arc stability and improved preheating without compromise
Solution Approach 2:
The electrical parameter (polarity) is changed between phases - DCEN for arc-start stability and DCEP for enhanced preheating and deposition. This parameter change allows optimization of arc characteristics for each specific phase, maintaining stability when needed and enhancing preheating when required
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 significantly improves deposition rates, weld quality, and arc-start characteristics, enabling efficient filling of deep and narrow grooves with reduced heat input and distortion, while maintaining consistent arc stability.
Implementation Method 1
applying a direct current electrode negative (DCEN) to the electrode using the welding tool to establish an arc between the electrode and a workpiece
Implementation Method 2
an electric arc is created when a voltage is applied between a consumable weld electrode wire, which serves as one electrode that advances towards a workpiece, and the workpiece, which serves as another electrode. The arc melts a tip of the metal wire
Implementation Method 3
applying a direct current electrode positive (DCEP) or alternating current (AC) to the electrode after the arc is established
Data Source
Figure 1
Figure 2
Figure 3A~3B
AI summary
The disclosed technology generally relates to welding technologies and more particularly to electrode assemblies for arc welding, e.g., submerged arc welding. In one aspect, a welding system comprises a welding power source and an electrode assembly operably coupled to the welding power source and an electrode. The welding power source is configured to apply a direct current electrode negative (DCEN) to the electrode using the electrode assembly to establish an arc between the electrode and a workpiece and to apply a direct current electrode positive (DCEP) or alternating current (AC) to the electrode after the arc is established.