Arc Welding Current Control for Thin Sheet Burn-Through Suppression
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Solution Overview
Problem
In thin sheet welding, pulse arc welding with high heat input tends to cause burn through and strain, leading to undercut and instability in the arc, which hinders productivity and welding quality, especially during high-speed welding.
Innovation Solution
An arc welding control method that alternately repeats periods of forward and reverse feeding of the welding wire, with distinct heat input periods to manage short-circuit and arc periods, reducing heat input by decreasing welding current after short-circuit release and maintaining a stable arc.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pulse arc welding with large heat input is used, then welding speed can be improved, but burn through and strain are easily generated
Solution Approach 1:
The patent applies periodic action by alternating between arc periods and short-circuit periods in a cyclic manner. During arc periods, welding current flows to provide heat input for melting; during short-circuit periods, the wire contacts the workpiece to transfer molten metal and reduce heat input. This periodic alternation allows the process to achieve both high welding speed and burn-through suppression
Solution Approach 2:
The patent changes the welding current parameter dynamically by switching between high current during arc periods and reduced or zero current during short-circuit periods. This parameter variation enables control over heat input amount, allowing high welding speed while preventing excessive heat accumulation that causes burn-through
2Productivity
If pulse arc welding with large heat input is used, then welding speed can be improved, but strain is generated in the welding subject
Solution Approach 1:
The periodic alternation between arc periods (heating) and short-circuit periods (metal transfer) creates intermittent heat input rather than continuous heating. This reduces cumulative thermal strain in the workpiece while maintaining adequate welding speed through efficient use of each heating cycle
Solution Approach 2:
By dynamically adjusting welding current between high levels during arc periods and low/zero levels during short-circuit periods, the patent controls the rate and distribution of heat input, preventing excessive thermal strain accumulation that would occur with sustained high current
3Object-affected harmful factors
If welding current is reduced to achieve reduced heat input, then burn through is suppressed, but arc becomes unstable
Solution Approach 1:
The periodic alternation ensures that the arc receives sufficient current during arc periods to maintain stability and proper arc characteristics, while during short-circuit periods the current is reduced to transfer metal and suppress burn-through. The rhythmical repetition stabilizes the overall process
Solution Approach 2:
The patent maintains continuous useful action by ensuring that each arc period successfully melts and transfers metal during the subsequent short-circuit period. This continuous cycle of melting and transfer keeps the arc engaged productively, preventing arc instability that would occur with prolonged current reduction
4Productivity
If high-speed welding is performed, then productivity is improved, but undercut is easily produced
Solution Approach 1:
The periodic short-circuit periods provide intermittent contact between the wire and workpiece, allowing molten metal to be deposited and solidify before the next arc period begins. This rhythmic deposition prevents the excessive heat concentration that causes undercut, even at high welding speeds
Solution Approach 2:
By reducing welding current to zero or low levels during short-circuit periods, the patent allows the molten pool to cool and solidify intermittently, preventing the sustained high-temperature conditions that lead to undercut formation, while maintaining high overall welding speed through efficient arc periods
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 method reduces heat input, suppresses burn through, improves gap tolerance, and prevents undercut, thereby enhancing welding quality and productivity while maintaining a stable arc during high-speed welding.
Implementation Method 1
an arc welding control method of performing welding output control by generating an arc between a welding wire that is a consumable electrode and a base material that is a welding subject
Data Source
Figure 1(a)~1(h)
Figure 2
Figure 3(a)~3(g)
AI summary
In thin sheet welding, when a heat input amount relative to a sheet thickness is too large, a welding defect such as a deviation from aim due to occurrence of a strain or burn through may easily occur. When a welding current is decreased to reduce the heat input amount, there is an issue in which an arc tends to become unstable. In arc welding in which short-circuit and arcing are repeated, first heat input period (Th) and second heat input period (Tc) having a heat input amount less than that of first heat input period (Th) are periodically repeated and a welding current during an arc period in second heat input period (Tc) is decreased to extinguish the arc. This reduces the heat input amount into a welding object and suppresses burn through or a strain upon welding, while making the arc stable.