Long Stick-Out SAW Arc Start With DCEN Polarity 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 establish an arc and then switches to direct current electrode positive (DCEP) or alternating current (AC) to improve arc-start characteristics and enhance deposition rates, using a long stick-out electrode assembly with increased electrical stick-out length for better preheating and control over energy input.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional DCEP or AC is applied to establish an arc in long stick-out SAW, then the arc can be established, but arc-start performance is suboptimal with inconsistent arc formation
Solution Approach 1:
The patent applies DCEN polarity during the arc-start phase before switching to DCEP or AC for production welding. This preliminary action with DCEN polarity enables reliable arc establishment and consistent arc formation, resolving the arc-start performance issues that occur with conventional direct DCEP or AC application.
2Temperature
If long stick-out electrode assembly is used to increase electrical stick-out length for better preheating, then preheating and control over energy input is improved, but arc-start performance deteriorates with conventional polarity
Solution Approach 1:
The patent implements a two-stage polarity approach: first applying DCEN during arc initiation to ensure reliable arc-start performance, then transitioning to DCEP or AC for the production phase. This preliminary DCEN action resolves the arc-start reliability issues that would otherwise occur with long stick-out configurations using conventional DCEP or AC polarity.
Solution Approach 2:
The patent changes the electrical polarity parameter during the welding process. By switching from DCEN (during arc-start) to DCEP or AC (during production welding), the system optimizes both arc-start reliability and deposition performance, resolving the contradiction between preheating benefits and arc-start performance deterioration.
3Productivity
If higher deposition rates are pursued in deep and narrow grooves, then productivity increases, but weld quality consistency deteriorates
Solution Approach 1:
The patent uses DCEN polarity during arc-start to establish consistent and reliable arc formation before production welding begins. This preliminary action ensures that the arc is properly established and stable, which enables maintaining weld quality consistency even when operating at higher deposition rates in deep and narrow grooves during the subsequent DCEP or AC production phase.
4Productivity
If DCEN is applied to establish an arc first, then arc-start performance and deposition rates improve, but process complexity increases due to polarity switching
Solution Approach 1:
The patent implements a time-sequential polarity switching approach where DCEN is applied only during the arc-start phase, followed by transition to DCEP or AC for production welding. This limited preliminary action with DCEN provides the benefits of improved arc-start performance and higher deposition rates while minimizing process complexity by using DCEN only for arc establishment rather than throughout the entire welding process.
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 system achieves significantly higher deposition rates and improved weld quality, especially in deep and narrow grooves, while minimizing arc striking issues and maintaining consistent arc formation, thus enhancing productivity and weld consistency.
Implementation Method 1
The welding power source is configured to apply 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
The arc melts a tip of the metal wire, thereby producing droplets of the molten metal wire that deposit onto the workpiece to form a weldment or weld bead
Data Source
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.