Two-Electrode Welding Method for Spatter Reduction
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Solution Overview
Problem
Conventional gas-shielded arc welding methods face challenges such as high spatter generation due to arc interference, limited deposition rate, and decreased mechanical properties of weld metal, particularly in tandem arc welding and hot wire TIG welding, where spatter reduction and high deposition efficiency are hindered by arc instability and heat input issues.
Innovation Solution
A two-electrode welding method using a leading arc electrode and a trailing filler electrode, where the trailing electrode is energized through electric resistance heating without generating an arc, with specific conditions for electrode distance, current ratios, and wire feeding speeds to minimize spatter and maximize deposition efficiency and mechanical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the feeding speed of a single-electrode wire is increased to increase deposition amount, then the deposition rate is improved, but the wire is excessively heated and melted before reaching the arc, causing hanging droplets to become unstable and generating a large amount of spatters
Solution Approach 1:
The welding process is divided into two separate electrode functions: a leading electrode that generates the arc and melts wire, and a trailing electrode that is pre-heated by resistance heating and then inserted into the molten pool. This segmentation allows each electrode to perform its function optimally without the harmful effects affecting the other.
Solution Approach 2:
The trailing electrode wire is pre-heated by resistance heating before it reaches the molten pool. This preliminary heating action reduces the thermal shock when the wire enters the molten pool, preventing excessive heating and spatter generation while maintaining high deposition rate.
2Productivity
If the number of revolutions of a feeding roller is increased to increase feeding speed, then the deposition rate is improved, but the feeding speed itself becomes unstable, affecting the arc
Solution Approach 1:
The feeding system is segmented into two independent wire feeding mechanisms, one for each electrode. This allows the trailing electrode feeding to be optimized for stability while the leading electrode feeding can be optimized for arc maintenance, with each system operating independently without相互 interference.
3Productivity
If an increase in electric current is applied to increase deposition rate, then the melting rate is improved, but the arc force excessively increases and the molten pool is dug deeply, resulting in flow defects such as undercut and humping
Solution Approach 1:
The current application is segmented between two electrodes: the leading electrode receives higher current to generate strong arc and melt wire, while the trailing electrode receives lower current primarily for resistance heating. This segmentation allows high current to be applied without the excessive arc force problems that would occur with a single electrode.
Solution Approach 2:
The trailing electrode acts as an intermediary that absorbs excess heat through resistance heating before the wire enters the molten pool. This intermediary function prevents the wire from being excessively heated by the arc, maintaining weld bead quality while enabling high deposition rates.
4Object-generated harmful factors
If the distance between electrodes is increased to reduce arc interference and spatter, then the amount of spatters is decreased, but a curved material to be welded cannot be tracked, the welding apparatus size increases, and the lack-of-welding area is increased
Solution Approach 1:
The electrode functions are segmented such that the leading electrode handles arc generation and the trailing electrode handles wire insertion. This functional segmentation allows the electrodes to be positioned close together (reducing apparatus size and improving tracking) while the trailing electrode's resistance heating reduces spatter by pre-heating the wire before pool entry.
5Reliability
If the electric current of one electrode is decreased to reduce arc interference, then the arc stability is improved, but the arc force becomes weak and is subjected to strong arc force from the other electrode, potentially increasing spatter
Solution Approach 1:
The current distribution is segmented between electrodes: the leading electrode receives high current for strong arc generation, while the trailing electrode receives low current for resistance heating only. This segmentation eliminates arc interference because only one electrode generates an arc, while the other provides thermal pre-conditioning of the wire.
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 significantly reduces spatter generation, increases deposition rate, and improves the toughness and strength of the weld metal while allowing for deep penetration and the use of cost-effective wires, achieving high deposition efficiency and sound welds with reduced heat input.
Implementation Method 1
the trailing electrode is an energized filler in which the temperature of the trailing electrode wire is increased by electric resistance heating through energization without generating an arc
Implementation Method 2
the leading electrode is used to perform gas-shielded arc welding in which the leading electrode wire is melted by generating an arc
Implementation Method 3
after the trailing electrode wire is inserted into the molten pool, the trailing electrode wire is melted through heat conduction of the molten pool
Data Source
AI summary
In a two-electrode welding method of the present invention, a leading electrode is used to perform gas-shielded arc welding and a trailing electrode is an energized filler. A trailing electrode wire protrudes from a guide lead or guide tip and is energized from an energizing tip. The distance between a welding surface and the energizing tip is 100 mm or more and 1500 mm or less. The distance between electrodes is 10 mm or less. The electric current of the leading electrode is 250 A or more, and the electric current of the trailing electrode is 10 A or more and 50% or less of the electric current of the leading electrode. The feeding speed of the trailing electrode wire is 20% or more and 50% or less of the feeding speed of the leading electrode wire.