Short-Arc Welding Current Dive Control for Spatter Reduction
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Solution Overview
Problem
Existing welding systems for short arc welding often produce spatter due to the rapid increase in current during the transition from short to arc state, which is not effectively mitigated by previous attempts such as resistance switching or predictive control.
Innovation Solution
A welding-type system with a controller that includes a peak short current detection module, an arc/short state detection module, a dive module, and a post dive module, which monitors and controls the output current to reduce spatter by rapidly decreasing the current at a dive rate and then maintaining it at a steady rate before returning to normal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the current increases rapidly during the transition from short to arc state in short arc welding, then the arc is established, but spatter is generated
Solution Approach 1:
The controller predicts when the arc will form based on the rate of change of output power (dp/dt) before the actual transition occurs. This prediction provides advance time to reduce the current command before the arc forms, preventing the rapid current increase that causes spatter while still establishing the arc reliably
Solution Approach 2:
The system uses feedback from the rate of change of output power to dynamically adjust the current command in real-time. By monitoring dp/dt, the controller can detect the approaching arc transition and respond by reducing the current command, creating a closed-loop control that prevents spatter generation
2Object-generated harmful factors
If predictive control is used to reduce current before arc formation, then spatter is reduced, but the control scheme becomes sophisticated and costly
Solution Approach 1:
The system uses the existing rate of change of output power (dp/dt) signal, which is already available in the welding system, to trigger the current reduction. This self-service approach uses existing system information rather than requiring additional complex sensors or measurement systems, keeping the control scheme relatively simple while achieving spatter reduction
3Device complexity
If a single inverter with inductor is used in the power circuit, then the system is simple, but the inductor becomes large adding cost and weight
Solution Approach 1:
The power circuit is segmented into two or more inverters or converters that are switched in sequence or parallel to provide the desired output. This segmentation eliminates the need for a large output inductor by using the switching action of multiple converters to smooth the output waveform, thereby reducing weight while maintaining circuit functionality
Data Source
AI summary
A method and apparatus for providing short arc welding-type power is disclosed. The system includes a power supply, a wire feeder, and a controller. The output current is decreased at dive rate when the arc forms. The dive rate is maintained until the currents drops to a threshold, preferably a function of the peak short current in that cycle. Then the current is held steady for a length of time that is a percentage of the short time for that cycle. Then the current is decreased at the normal rate until the short reforms, and the current begins increasing at the normal rate. The holding steady portion can be omitted.