Short-Arc Weld Current Control with Open-Circuit Suppression
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Solution Overview
Problem
Existing systems for controlling weld-current in short arc welding face challenges in stabilizing the process due to the occurrence of open circuit states, which lead to inefficient and low-quality welding, as voltage regulators misinterpret high open circuit voltages, causing frequent open circuit phases and reduced output voltage.
Innovation Solution
A system with a current regulator in a voltage feedback loop and a ramp generator, where an open circuit detector suppresses error signals to the current regulator, and the ramp generator provides current ramps during short circuits, allowing for separate voltage and current control phases to stabilize the welding process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a voltage regulator is used to control the power source, then the voltage can be maintained, but open circuit states occur frequently causing process instability and reduced welding quality
Solution Approach 1:
The welding cycle is segmented into distinct phases (arc phase and short circuit phase), with different control strategies applied to each phase. During the arc phase, voltage control is active, while during the short circuit phase, current control takes over. This segmentation allows the system to avoid the instability caused by voltage regulation during short circuits while maintaining voltage control during stable arcing, thereby improving both process reliability and welding efficiency.
2Measurement precision
If voltage control is applied during short circuit phase, then voltage regulation is achieved, but the high open circuit voltage is misinterpreted causing frequent open circuit phases
Solution Approach 1:
The control system dynamically switches between voltage control and current control based on the detected welding phase. During the arc phase, voltage control is active with the voltage feedback loop engaged. During the short circuit phase, the system transitions to current control by disabling the voltage feedback loop. This dynamic adaptation allows accurate measurement and control during each phase without the harmful effects of applying inappropriate control during phase transitions, thereby maintaining arc stability while preserving measurement precision.
3Device complexity
If current ramps are not provided during short circuit, then the control system is simpler, but molten droplet transfer is incomplete causing splatter
Solution Approach 1:
The ramp generator pre-calculates and provides current ramps in advance during the short circuit phase. The current ramp is generated based on the detected short circuit condition, creating a controlled current increase that facilitates complete molten droplet transfer to the workpiece before detachment. This preliminary action ensures proper metal transfer and minimizes splatter while adding only minimal complexity through a dedicated ramp generation component.
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 solution enables accurate control of the weld-current during both arc and short circuit phases, reducing the influence of open circuit states and improving the stability and quality of the welding process by maintaining a stable arc and minimizing splatter.
Implementation Method 1
an electric arc is established between the work piece and the consumable wire electrode. The arc continuously melts the wire as it is fed to the weld puddle
Implementation Method 2
The arc continuously melts the wire
Implementation Method 3
The arc and the molten material are shielded from the atmosphere by a flow of an inert gas, or an active gas mixture
Implementation Method 4
a voltage feedback loop from a power supply to a welding electrode
Implementation Method 5
A current regulator included in a voltage feedback loop from a power supply to a welding electrode
Implementation Method 6
a ramp generator arranged to provide current ramps during a short circuit phase at said welding electrode
Implementation Method 7
an open circuit detector arranged to detect a high voltage between the welding electrode and the work piece at a said open circuit state and to suppress an error signal to said current regulator
Data Source
AI summary
A system for controlling a weld-current in an arc welding apparatus for short arc welding comprising a current regulator included in a voltage feedback loop from a power supply to a welding electrode and a ramp generator arranged to provide current ramps during a short circuit phase at said welding electrode.