Modified Series Arc Welding for Pipe Seam Tack
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Solution Overview
Problem
Conventional pipe seam tack welding processes are limited by low deposition rates and high arc force, which can result in arc drive-through and excessive workpiece heating, making them unsuitable for high-speed pipe welding operations without compromising seam integrity.
Innovation Solution
A modified series arc welding technique using two electrodes connected in series, with short-circuit and arc phases, and selective electrode current polarity reversal to control arc force and deposition rate, facilitating high-quality welds at increased deposition rates without arc drive-through.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional short-circuit arc welding is used for pipe seam tack welding, then arc force is controlled to prevent drive-through, but deposition rate is limited and welding speed is slow (3-5 meters per minute)
Solution Approach 1:
The welding process is divided into two separate arcs: a primary arc for controlled deposition and a secondary arc for providing additional molten metal. This segmentation allows each arc to perform its specific function independently, enabling high deposition rates while maintaining control over arc force and preventing drive-through.
Solution Approach 2:
The primary arc acts as an intermediary between the power source and the workpiece, controlling the main deposition process. The secondary arc provides additional molten metal without directly contacting the workpiece, serving as a mediator that increases deposition rate while the primary arc maintains control over heat input and prevents harmful effects.
2Productivity
If high current is used to increase deposition rate, then welding speed increases, but workpiece heating becomes excessive and arc drive-through occurs
Solution Approach 1:
The total current is segmented between two arcs, with the primary arc carrying controlled current for steady deposition and the secondary arc providing additional current for increased deposition rate. This segmentation prevents excessive current concentration that would cause overheating and drive-through while maintaining high overall deposition rate.
Solution Approach 2:
The process parameters (current, voltage, wire feed speed) are dynamically adjusted based on the welding condition. The system transitions between different parameter states to optimize deposition rate while preventing excessive heating, allowing high welding speeds without compromising workpiece integrity.
3Productivity
If high wire feed speed is used to increase deposition rate, then welding speed increases, but arc force increases causing drive-through
Solution Approach 1:
The wire feed is segmented into two streams: one for the primary arc and one for the secondary arc. This allows the system to utilize high wire feed speeds for increased deposition without concentrating all the arc force on a single arc, thereby preventing drive-through while maintaining high productivity.
Solution Approach 2:
The secondary arc provides partial action by contributing additional molten metal without performing the complete welding function. This excessive action (providing more metal than strictly necessary) increases deposition rate while the primary arc performs the controlled welding, distributing the arc force and preventing harmful effects.
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 enables high deposition rates and improved seam integrity during pipe seam tack welding, allowing for faster lineal welding speeds while preventing arc drive-through and excessive workpiece heating.
Implementation Method 1
providing first and second currents to the electrodes to establish a first arc between the first electrode and the workpiece and a second arc between the first and second electrodes
Implementation Method 2
depositing molten metal from one or both electrodes onto the workpiece
Data Source
AI summary
Welders and methods are presented for short-circuit arc welding a workpiece using a modified series arc welding configuration with two electrodes via a sequence of welding cycles, in which each cycle includes an arc condition a short-circuit condition, wherein one or both electrode currents are selectively reversed during a reverse boost portion of the welding cycle to transfer molten metal from the second electrode to the first electrode prior to a short-circuit condition of a subsequent welding cycle.