CO2 Arc Welding Current Phasing for Short-Circuit Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In arc welding using carbon dioxide as a shield gas, the large arc reaction force destabilizes droplet behavior, leading to a high likelihood of minute short circuits and sputtering, particularly during globular transfer, where conventional methods are insufficient in suppressing these issues.
Innovation Solution
The method involves alternating short circuit and arc periods, with specific current control phases: increasing the welding current to establish an initial arc length, then reducing it to lower the arc reaction force, and further adjusting to stabilize droplet growth and maintain a constant transfer cycle.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the welding current is increased in the initial stage of the arc period to ensure arc length, then the arc length is maintained, but the arc reaction force increases causing droplet behavior instability and minute short circuits
Solution Approach 1:
The patent applies periodic action by dividing the arc period into multiple phases with different current levels. The welding current is increased in the initial stage to ensure arc length, then reduced in the middle stage to stabilize droplet behavior and prevent minute short circuits, and finally increased again in the final stage. This periodic modulation of current resolves the contradiction between maintaining arc length and stabilizing droplet behavior.
Solution Approach 2:
The patent implements dynamics by making the welding current adjustable and time-dependent rather than constant. The current value changes dynamically throughout the arc period based on the specific phase and droplet transfer requirements, allowing the system to adapt to different operational conditions and resolve the contradiction between arc length maintenance and droplet stability.
2Object-generated harmful factors
If the welding current is decreased to suppress minute short circuits and sputtering, then sputtering is reduced, but the arc length becomes unstable and droplet transfer cycle becomes inconsistent
Solution Approach 1:
The patent uses periodic action by implementing a multi-stage current control where the welding current is decreased only during the middle stage of the arc period when droplet transfer occurs, while maintaining higher current levels in the initial and final stages. This selective periodic reduction suppresses sputtering and minute short circuits during the critical droplet transfer phase while preserving arc length stability and droplet transfer cycle consistency through appropriate current levels in other 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
This approach effectively suppresses minute short circuits and sputtering, ensuring a consistent droplet transfer cycle and high-quality welding by stabilizing droplet behavior and controlling arc length.
Implementation Method 1
an arc is generated between the base material and the welding wire to input heat to the base material
Implementation Method 2
arc reaction force applied to droplets formed at the leading end of the welding wire become large
Data Source
Figure 1
Figure 2A~2A(f)
Figure 2B~2B(c)
AI summary
Base material (17) is welded by using carbonate dioxide as a shield gas and alternately repeating short circuit period (Ts) and arc period (Ta). In short circuit period (Ts), welding current (I) is increased from pre-arc regeneration current value (10) to first current value (I1). When the welding current reaches a current value at a time of arc generation that is a time of short circuit opening, arc (20), and switching takes place from short circuit period (Ts) to arc period (Ta). In first period (T1) of arc period (Ta), welding current (I) is increased up to first current value (I1) with first inclination (α) so that an arc length of arc (20) becomes first length (L1). In second period (T2), welding current (I) is decreased down to second current value (I2) (I0 < I2 < I1) with second inclination (β) to reduce arc reaction force applied to droplets (21) at a leading end of welding wire (18). In third period (T3), welding current (I) is increased up to third current value (I3) (I2 < I3 < I1) with third inclination (γ) so that the arc length of arc (20) becomes second length (L2).