Double-Electrode Gas Metal Arc Welding

All conventional arc welding processes have a common arcing mechanism which uses the base metal as one terminal of the arc. For gas metal arc welding (GMA W), which is considered the most widely used process for metal joining and installed in most arc welding robots, this arcing mechanism means metal transfers between arc terminals and fluctuations in arcing conditions. Metal transfer control technologies try to minimize the fluctuations to improve arc stability and weld quality using different techniques, but do not change the fundamental aspects of the arcing mechanism. Further, the heat associated with the arc cathode directly melts the base metal and contributes to enlarging the weld pool and distortion. As a result, use of high currents for high deposition rates is impractical unless backing is used to support the resultant large weld pool. It is apparent that to improve the weld quality and productivity substantially, the arcing mechanism in conventional GMA W must be modified or changed fundamentally. The PI thus proposes an innovative arcing mechanism which establishes the arc between two consumable electrodes, and refers to the resultant process as double-electrode gas metal arc welding or DEGMA W. In DE-GMA W, auxiliary arcs can still be established between the electrodes and the base metal. However, the currents of auxiliary arcs are adjusted to transfer the droplets and to regulate the arc heat on the base metal for sufficient fusion with liquid droplets, and thus are different from the main current which is used to melt the electrodes. Although the verification, demonstration and operation of the proposed process require understanding, modeling, and control of the double-electrode gas metal arcing process, the proposed arcing mechanism appears sound. The likelihood of successfully verifying, demonstrating and operating the DE-GMA W is thus relatively high. In addition, the proposed studies involve heat transfer, arc radiation, fluid mechanics, numerical modeling, materials, control system/theory, circuits, computer hardware/software, and problem solving. A knowledge base can thus be established to understand and support the operation and optimization of the promising DE-GMA W process. In terms of its broader impact, this research will first provide opportunities to train participating graduate students through challenging multi-disciplinary research and industrycollaborations via the case study. Second, the PI plans developing a program to train manufacturing engineers and gradate/undergraduate students and offering credited and non-credit short courses on control based manufacturing. The proposed research will provide excellent first-hand materials and appropriate applications and examples for this program. In addition, the PI will identify appropriate topics for two outstanding undergraduate students, with one or two from under-represented groups, and for two exceptional high school students to attract them to graduate school and to choose engineering careers.