Numerical analysis of the dynamic growth of droplets in gas metal arc welding

Feedback control of droplet transfer is pursued as a solution to produce sound welds in gas metal arc welding. In previous work, a real-time visual system has been developed to monitor on line the droplet size and geometry. To realize feedback control of metal transfer, this study addresses the dynamic process of droplet growth and detachment. The droplet is subjected to gravitational force, electromagnetic force, plasma drag force and surface tension force. The geometry of the droplet is determined by these forces through the static force balance. However, the forces acting on the droplet continuously change as the melting electrode wire changes the droplet geometry. Because of this interdependence between the droplet geometry and the forces, the model must be solved dynamically and iteratively. A numerical program has been developed to acquire its dynamic numerical solution. Hence, the dynamics of the metal transfer process can be understood and simulated. Currently, this model is being used to simulate theclosed-loop controlled metal transfer process using different advanced control technologies.

Download Full-text

Mechanically assisted droplet transfer process in gas metal arc welding

Proceedings of the Institution of Mechanical Engineers Part B Journal of Engineering Manufacture ◽

10.1243/0954405021520247 ◽

2002 ◽

Vol 216 (4) ◽

pp. 555-564 ◽

Cited By ~ 19

Author(s):

Y Wu ◽

R Kovacevic

Keyword(s):

Transfer Process ◽

Arc Welding ◽

High Speed ◽

Gas Metal Arc Welding ◽

Metal Transfer ◽

Droplet Transfer ◽

Macroscopic Appearance ◽

Transfer Mode ◽

Metal Arc Welding ◽

Separate Control

Gas metal arc welding has been generally accepted as the preferred joining technique due to its advantages in high production and automated welding applications. Separate control of arc energy and arc force is an essential way to improve the welding quality and to obtain the projected metal transfer mode. One of the most effective methods for obtaining separate control is to exert an additional force on the metal transfer process. In this paper, the droplet transfer process with additional mechanical force is studied. The welding system is composed of an oscillating wire feeder. The images of molten metal droplets are captured by a high-speed digital camera, and both the macroscopic appearance and the cross-sectional profiles of the weld beads are analysed. It is shown that the droplet transfer process can be significantly improved by wire electrode oscillation, and a projected spray transfer mode can be established at much lower currents. By increasing the oscillation frequency, the droplet transfer rate increases while the droplet size decreases. In addition, the improvement in the droplet transfer process with wire oscillation leads to an enhancement of the surface quality and a modification of the geometry of the weld beads that could be of importance for overlay cladding and rapid prototyping based on deposition by welding.

Download Full-text

Analysis and Improvement of Metal Transfer Behaviors in Consumable Double-Electrode GMAW Process

Journal of Manufacturing Science and Engineering ◽

10.1115/1.4028636 ◽

2015 ◽

Vol 137 (1) ◽

Cited By ~ 3

Author(s):

Ming Zhu ◽

Yu Shi ◽

Ding Fan

Keyword(s):

Arc Welding ◽

Gas Metal Arc Welding ◽

Metal Transfer ◽

Force Balance ◽

Current Electrode ◽

Main Metal ◽

Metal Arc Welding ◽

Weld Appearance ◽

Double Electrode ◽

Welding Consumable

Consumable double-electrode gas metal arc welding (consumable DE-GMAW) is the efficient improvement of DE-GMAW. Due to the variety of coupled arc and metal transfer behaviors, this paper applies static force balance theory to analyze the changes in the forces acting on the main and bypass droplets separately. For main torch, the bypass arc changes the forces affecting on the main droplet, and the main metal transfer becomes more desirable. For bypass torch, with direct current electrode negative (DCEN) polarity, the volume of droplet is big and not easily transfers to the weld pool. In order to improve the bypass metal transfer, a method has been proposed which adds CO2 to pure argon shielding gas to change the forces affecting on the bypass droplet. Then, the welding experiment is carried out to test the effectiveness of this method. It is found that bypass droplet transfers easily and the diameter of bypass droplet is decreased significantly. Also a good weld appearance is acquired.

Download Full-text

Metal transfer process and properties of double-wire double pulsed gas metal arc welding

Journal of Manufacturing Processes ◽

10.1016/j.jmapro.2019.06.019 ◽

2019 ◽

Vol 44 ◽

pp. 367-375 ◽

Cited By ~ 7

Author(s):

Kaiyuan Wu ◽

Xuanwei Cao ◽

Tong Yin ◽

Min Zeng ◽

Zhuoyong Liang

Keyword(s):

Transfer Process ◽

Arc Welding ◽

Gas Metal Arc Welding ◽

Metal Transfer ◽

Metal Arc Welding

Download Full-text

Effect of Current Waveform on Metal Transfer in Controlled Short Circuiting Gas Metal Arc Welding

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.718-720.202 ◽

2013 ◽

Vol 718-720 ◽

pp. 202-208 ◽

Cited By ~ 1

Author(s):

Mao Ai Chen ◽

Yuan Ning Jiang ◽

Chuan Song Wu

Keyword(s):

Transfer Process ◽

High Speed ◽

Gas Metal Arc Welding ◽

Welding Current ◽

Metal Transfer ◽

Arc Voltage ◽

Metal Arc Welding ◽

Maximum Stability ◽

The Stability ◽

Welding Inverter

With high-speed welding inverter and precisely controlling the welding current with arc-bridge state, advanced pulse current waveforms can be produced to optimize the transfer characteristics of short circuiting transfer welding. In this paper, the images of droplet/wire, and the transient data of welding current and arc voltage were simultaneously recorded to study the influence of peak arcing current, background arcing current and tail-out time on the stability of short circuiting transfer process. It was found that maximum short circuiting transfer stability is reached under specific welding conditions. Any deviation from these conditions will cause abnormal rises in arc voltage indicating instantaneous arc extinguishing and greater spatter. Optimal welding conditions were obtained to achieve the maximum stability of short circuiting metal transfer process.

Download Full-text