Gas-Shielded Arc Welding Control for Spatter-Free Droplet Separation
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Solution Overview
Problem
In carbon dioxide gas-shielded arc welding, preventing spatter generation during molten droplet separation while maintaining constant arc length has not been effectively addressed, particularly under middle to high current conditions, without causing a short circuit between the molten droplet and the molten pool.
Innovation Solution
A control method for gas-shielded arc welding that involves detecting the separation timing of the molten droplet and implementing a controlled welding current profile, including a current decreasing section, a maintaining section, and a current increasing section, along with adjustments in arc voltage, wire feeding speed, and gas ratio to prevent short circuits and spatter formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If pulse waveform control is used to actively form molten droplet and separate it using base modulation waveform control, then molten droplet separation is achieved, but arc length control in pulse peak period becomes difficult and spatter reduction effect is insufficient
Solution Approach 1:
The patent applies periodic pulse waveform control with distinct peak and base periods. During the peak period, a high current pulse actively forms the molten droplet, followed by a base period where the current is reduced to facilitate separation. This periodic action enables controlled droplet formation and separation while maintaining arc length stability through the cyclic nature of the waveform.
Solution Approach 2:
The patent changes the current parameter dynamically through pulse waveform control. The current is increased to a peak value during the peak period to form the droplet, then reduced to a base value during the base period for separation. This parameter change strategy allows precise control of droplet behavior while maintaining ease of operation through standardized waveform patterns.
2Manufacturing precision
If molten droplet is oscillated in peak period to form desired size, then droplet formation is improved, but minute spatter is generated during oscillation
Solution Approach 1:
The patent uses periodic pulse waveform control where the peak period creates controlled oscillations to form the droplet to the desired size, and the subsequent base period provides a calm phase that allows the droplet to stabilize before separation. This periodic action reduces minute spatter by providing a transition phase between formation and separation.
Solution Approach 2:
The welding process is segmented into distinct peak and base periods. The peak period handles droplet formation and oscillation, while the base period handles stabilization and separation. This segmentation allows each phase to be optimized independently, reducing spatter generation during the transition between formation and separation.
3Speed
If short circuit is used to migrate molten droplet in base period, then droplet migration is achieved, but spatter is generated when short circuit is released
Solution Approach 1:
The patent employs periodic pulse waveform control where the base period provides a controlled, low-current phase that enables gentle droplet migration without the abrupt effects of short circuiting. The cyclic nature of the waveform ensures smooth transitions that prevent spatter generation upon release.
Solution Approach 2:
The patent prevents the harmful effect of spatter by avoiding short circuiting altogether. Instead, the base period uses reduced current to create a preliminary anti-action that counteracts the tendency for spatter generation, providing a smooth migration path for the droplet without abrupt releases.
4Productivity
If middle to high current condition is used for gas-shielded arc welding with CO2 containing shielding gas, then welding productivity is improved, but large particle spatter is generated due to arc reaction force concentrating below molten droplet
Solution Approach 1:
The patent applies periodic pulse waveform control that modulates the current between peak and base values. During the peak period, high current provides strong arc reaction force for productivity, while the base period reduces current to allow droplet separation before the arc reaction force can cause large particle spatter. This periodic modulation enables high productivity while minimizing spatter.
Solution Approach 2:
The patent dynamically changes the current parameter using pulse waveform control. The current is increased to high values during the peak period to maintain productivity, then reduced to lower values during the base period to prevent spatter. This parameter change strategy allows the system to operate at high productivity levels while controlling spatter through temporal separation of high-current and low-current phases.
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 method achieves an excellent bead appearance by preventing spatter generation during molten droplet separation without causing a short circuit, ensuring stable welding conditions and reducing spatter formation.
Implementation Method 1
an arc reaction force concentrates immediately below a molten droplet due to a pinch of the arc, and a repulsive force to push up the molten droplet increases
Implementation Method 2
a welding current is controlled by detecting a separation timing of a molten droplet at a welding wire tip melted by an arc
Data Source
AI summary
A control method for gas-shielded arc welding includes providing a normal arc period in which the welding current is maintained at a setting current Icc set in advance, and providing a separation control period after the separation timing of the molten droplet is detected in the normal arc period, the separation control period including a current decreasing section, a current maintaining section, and a current increasing section. In the separation control period, at least one of the following controls for preventing a short circuit is performed: control of an output voltage, control of a feeding speed, and control of a gas ratio.