Multi-Electrode Submerged Arc Welding with Phase-Controlled AC
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Solution Overview
Problem
Multi-electrode submerged arc welding faces challenges in achieving optimal welding stability and reducing arc oscillation due to the discontinuous phase differences in AC current, leading to weld defects and gas blowing up, despite the use of connections like Scott, V, and inverted V connections.
Innovation Solution
Employing a digitally controlled welding power supply to freely control the phase, waveform, and frequency of AC current, allowing for the optimization of electromagnetic force on the arc column, thereby reducing arc oscillation and improving weld metal shape and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Scott connection, V connection, or inverted V connection is used to combine AC power supplies, then welding stability and weld metal shape are improved, but arc oscillation cannot be sufficiently prevented and welding conditions cannot be optimized
Solution Approach 1:
The invention changes the phase difference parameter from fixed discrete values (60°, 90°, 120°, 135°, 150°) to continuously adjustable values. By using a digitally controlled welding power supply, the phase difference between AC currents can be precisely adjusted to any value, allowing optimal control of electromagnetic force to prevent arc oscillation while maintaining welding stability.
Solution Approach 2:
The invention transitions from static fixed phase difference connections to dynamic adjustable phase difference control. The welding power supply can dynamically adjust the phase difference during welding operations, enabling real-time optimization of electromagnetic force balance to eliminate arc oscillation under varying welding conditions.
2Device complexity
If fixed phase difference connections are used, then device complexity is reduced, but manufacturing precision and weld quality are compromised
Solution Approach 1:
The invention replaces mechanical connection structures (Scott connection, V connection, inverted V connection) with digital control systems. Instead of using complex electrical connection arrangements to achieve phase control, the system uses a digitally controlled welding power supply to electronically adjust phase differences, simplifying the physical connection structure while enhancing precision control capabilities.
3Ease of operation
If AC current with fixed phase difference is used, then ease of operation is maintained, but welding precision and defect reduction are limited
Solution Approach 1:
The digitally controlled welding power supply automatically adjusts the phase difference to optimal values based on welding parameters and conditions. The system self-regulates the electromagnetic force balance between electrodes, eliminating the need for manual calculation and adjustment of phase differences while ensuring optimal weld quality and preventing arc oscillation.
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 effectively prevents arc oscillation, enhances welding stability, reduces weld defects, and suppresses gas blowing up, resulting in improved weld quality and consistency.
Implementation Method 1
Arc oscillation during welding is mainly caused by the electromagnetic force generated by AC current
Implementation Method 2
AC currents with a lagging phase of 90° because of the self-induction action of coils
Data Source
Figure 1
Figure 2~4
AI summary
A multi-electrode submerged arc welding method using a plurality of electrodes is provided. For each of a second electrode to an nth electrode except a first electrode that is a front electrode in a welding direction where n is an integer of 2 or more: a welding power supply capable of controlling a waveform of a welding current is used; and when a maximum value of an electromagnetic force Fi acting on an arc column at a wire tip of an ith electrode during welding is denoted by Fimax in N/m, an average value of the electromagnetic force Fi is denoted by Fiave in N/m, and a standard deviation of the electromagnetic force Fi is denoted by σFi in N/m, welding is performed so that Fimax, Fiave, and σFi satisfy relationships in Expressions (1) and (2).