Buried Arc Welding Current Control for Single-Pass Thick Plates
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Solution Overview
Problem
Conventional gas shielded arc welding methods for thick plates require multi-layer welding, leading to increased heat input, deformation, and embrittlement, and struggle to maintain a stable buried arc due to unstable liquid columns and sputtering issues.
Innovation Solution
The method involves supplying a welding current of 300A or more with alternating small and large current periods to control the position of the welding wire tip within a buried space, stabilizing the arc and preventing sputtering by varying the current frequency between 10Hz to 1000Hz, ensuring deep penetration and maintaining a stable buried space.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If multi-layer welding is used to weld thick plates, then welding can be achieved, but the number of welding steps increases and heat input increases causing deformation and embrittlement
Solution Approach 1:
The patent applies periodic action by alternating between small current periods and large current periods during welding. The small current periods allow droplet transfer to the bottom of the melted portion while large current periods enable droplet transfer to the side part, creating a periodic cycle that maintains stable buried arc welding throughout the single pass process
Solution Approach 2:
The patent changes welding current parameters dynamically by periodically varying between small and large current values. This parameter change enables control over droplet transfer location and maintains the buried arc state, allowing single pass welding of thick plates without the deformation and embrittlement caused by multi-layer welding
2Productivity
If welding wire is fed at high speed with large current to achieve single pass welding, then a buried arc is formed, but the liquid column becomes unstable causing sputtering
Solution Approach 1:
The patent uses periodic action by alternating small and large current periods to stabilize the liquid column. During small current periods, the liquid column contracts and droplets transfer to the bottom; during large current periods, the liquid column expands and droplets transfer to the side. This periodic cycle prevents the liquid column from becoming excessively long and unstable, thereby reducing sputtering while maintaining buried arc welding
Solution Approach 2:
The patent implements feedback control by monitoring the welding process state and adjusting current parameters accordingly. The periodic alternation between small and large currents responds to the dynamic state of the liquid column, maintaining optimal conditions for stable buried arc welding and preventing sputtering
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 allows for single-pass welding of thick plates with reduced sputtering and deformation, maintaining a stable buried space and improving the overall welding process by controlling the liquid column length and arc direction.
Implementation Method 1
generating arc between a base material and a welding wire fed to a to-be-welded portion of the base material, to weld the base material by heat of arc
Implementation Method 2
supplying large current of 300A or more... High-speed feeding of welding wire and supply of large current form a concave melted portion at the base material due to the heat of arc
Data Source
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AI summary
An arc welding method of a consumable electrode type generating arc between a tip end of welding wire (5) and a to-be-welded portion by feeding welding wire to the to-be-welded portion of a base material (4) while supplying welding current having average current of 300A or larger to the welding wire (5), to weld the base material (4), includes: feeding the welding wire at a speed of the tip end being inserted into a space surrounded by a concave melted portion formed in the base material by the arc generated between the tip end and the to-be-welded portion; periodically alternating between a small current period where the welding current has a small average value and droplet is transferred from the tip end to a bottom part of the melted portion and a large current period where the welding current has a large average value and droplet is transferred from the tip end to a side part of the melted portion; and controlling the welding current in the large current period so that droplet transfer from the tip end to the side part is performed a plurality of times in each large current period.