Welding Arc Termination via Conduction Angle Control
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Solution Overview
Problem
Welding systems face issues where stored energy in capacitor banks can cause the welding wire to stick to the workpiece or leave marks due to incomplete discharge after a welding operation, necessitating a method to effectively terminate the welding arc and dissipate energy.
Innovation Solution
A welding system and method that includes a control circuitry to receive a signal for arc termination, stop the welding wire advance, and reduce the conduction angle of solid state switches to dissipate energy stored in the capacitive circuit through the welding arc, ensuring complete discharge and preventing workpiece damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a burden resistor is installed across the capacitor bank to discharge it, then the capacitor bank can be discharged after welding operation, but the system complexity increases and the discharge may still be incomplete causing wire sticking or workpiece marking
Solution Approach 1:
The patent makes the capacitive circuit discharge itself through the welding arc by reducing the conduction angle of solid state switches, eliminating the need for external burden resistors or discharge circuits. The welding arc itself serves as the discharge path, converting the harmful residual energy into useful welding heat that completes the weld pool formation.
Solution Approach 2:
The patent converts the harmful residual energy in the capacitive circuit, which normally causes wire sticking or workpiece marking, into a beneficial effect by directing it through the welding arc. The reduced conduction angle causes the capacitive circuit to discharge through the arc, providing additional heat that ensures complete weld pool formation and prevents defects.
2Productivity
If the welding arc is terminated immediately when operator releases the trigger, then the welding process stops quickly, but residual energy in the capacitive circuit causes wire sticking or workpiece marking
Solution Approach 1:
The patent performs preliminary discharge of the capacitive circuit by reducing the conduction angle before the welding arc is completely terminated. This preliminary action ensures that residual energy is dissipated through the welding arc while it still exists, preventing wire sticking or workpiece marking when the arc is finally extinguished.
Solution Approach 2:
The patent dynamically adjusts the conduction angle of solid state switches during the welding process. When the operator releases the trigger, the controller reduces the conduction angle from its normal welding value to a lower value, creating a controlled transition phase that dissipates capacitive energy while maintaining arc continuity until complete discharge is achieved.
3Reliability
If the conduction angle of solid state switches is reduced to dissipate capacitive energy, then complete discharge is achieved, but the welding power output decreases
Solution Approach 1:
The patent uses periodic AC cycling with varying conduction angles to discharge the capacitive circuit. By reducing the conduction angle during specific AC cycles after trigger release, the system dissipates energy in controlled periodic pulses while maintaining overall system stability and preventing power output issues.
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 solution effectively reduces the likelihood of wire sticking and workpiece marking by incrementally decreasing power to the weld arc, allowing for controlled discharge of the capacitive circuit, thereby ensuring a clean and safe termination of the welding process.
Implementation Method 1
dissipate energy stored in the capacitive circuit through the welding arc
Implementation Method 2
welding arc generated by a welding system
Data Source
AI summary
A system and method for welding arc termination are provided. In an exemplary embodiment, a method for controlling a welding process includes receiving a signal indicating an operator intention to terminate a welding arc and stopping advance of a welding wire in response to the signal. The method also includes reducing a conduction angle for switching of solid state switches that generate welding power in response to the signal.