scholarly journals Influence of Polarity Arrangement of Inter-Wire Arc on Droplet Transfer in Cross-Coupling Arc Welding

Materials ◽  
2019 ◽  
Vol 12 (23) ◽  
pp. 3985 ◽  
Author(s):  
Shanwen Dong ◽  
Fan Jiang ◽  
Bin Xu ◽  
Shujun Chen
Keyword(s):  
Critical Current ◽  
High Speed ◽  
Cathode Spot ◽  
Cross Coupling ◽  
Input Voltage ◽  
Electric Signal ◽  
Droplet Transfer ◽  
Spray Transfer ◽  
Globular Transfer ◽  
Comprehensive Comparison

In order to reduce the influence of polar zone effect in cross-coupling arc by changing inter-wire arc (IWA) configuration, the influence of polarity arrangement of the IWA on droplet transfer was studied. The change of voltage-current waveform and the process of droplet transfer were recorded and analyzed by a high-speed camera and electric signal synchronous acquisition system. The results show that when the IWA polarity is arranged as anode on the bottom and cathode on top, the anode spot force always promotes the droplet transfer and reduces the critical current value of spray transfer. However, with the increase in the input voltage of the IWA, the resistance of the cathode spot force becomes obvious, which hinders the droplet transfer. While the IWA polarity is arranged as anode on top and cathode on the bottom, increasing the input voltage of the IWA obviously reduces the plasma arc voltage. The critical current of spray transfer increases in anode droplet, while the cathode droplet is mainly globular transfer, and there is no spatter explosion process. Through a comprehensive comparison of the droplet transfer process of anode and cathode under the different IWA polarity arrangement, the process of anode and cathode in the IWA polarity arrangement of the anode on top and the cathode on the bottom is more stable than that in the IWA polarity arrangement of the anode on the bottom and the cathode on top, mainly because the cathode spot force under high current do not hinder the cathode droplet.

scholarly journals Characteristics of Magnetic Field Assisting Plasma GMAW-P

2020 ◽  
Vol 99 (1) ◽  
pp. 25s-38s
Author(s):  
JIANG YU ◽  
◽  
BO WANG ◽  
HONGTAO ZHANG ◽  
PENG HE ◽  
...  
Keyword(s):  
Magnetic Field ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Welding Current ◽  
Plasma Welding ◽  
Droplet Transfer ◽  
Spray Transfer ◽  
The Wire ◽  
Indirect Arc ◽  
The Magnetic Field

The droplet transfer and voltage-current characteristics of gas metal arc welding (GMAW) in single-pulsed GMAW (single GMAW-P), plasma pulsed GMAW (plasma GMAW-P), and plasma-GMAW-P with a magnetic field were studied using the synchronous acquisition system of high-speed camera and electric signals. The results showed the plasma arc and magnetic field had a significant effect on the droplet transfer process. The indirect arc of the plasma and gas metal arc emerged in the pulse peak phase causing a shunt phenomenon of the GMAW current. The period of the indirect arc was increased under the action of the magnetic field. In hybrid plasma GMAW-P, when the GMAW current did not exceed 140 A, several pulsed one-drop free transfers occurred and the droplet transfer period decreased with the increase in the plasma welding current; when the GMAW current exceeded 140 A, and the plasma welding current was less than 180 A, spray transfer was formed. The droplet transfer transformed into a projected transfer when the plasma welding current increased to 180 A. In plasma-GMAW-P hybrid welding with a magnetic field, the magnetic field had a slight effect on the transfer period. When the GMAW current did not exceed 140 A, the droplet transfer was mainly repelled transfer. The detaching location was on the right side of the wire when the magnetic field current was less than 3 A. When the magnetic field current exceeded 3 A, it was below or on the left side of the wire. When the GMAW current exceeded 140 A and the magnetic field current was less than 5 A, spray transfer was formed, but the droplet transfer mode transformed into a projected transfer with a magnetic field current of 5 A.

scholarly journals Effects of active gases on droplet transfer and weld morphology in pulsed-current NG-GMAW of mild steel

2020 ◽  
Author(s):  
Guoqiang Liu ◽  
Xinhua Tang ◽  
Qi Xu ◽  
Fenggui Lu ◽  
Haichao Cui
Keyword(s):  
Mild Steel ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Welding Process ◽  
Metal Transfer ◽  
Pulsed Current ◽  
Shielding Gas ◽  
Droplet Transfer ◽  
Spray Transfer ◽  
Pure Argon

Abstract Small amount of active gases CO 2 and O 2 were added into pure argon inert shielding gas to improve the weld formation of pulsed-current narrow-gap gas metal arc welding (NG-GMAW) of mild steel. Their effects on droplet transfer and arc behavior were investigated. A high-speed visual sensing system was utilized to observe the metal transfer process and arc morphology. When the proportion of CO 2 , being added into the pure argon shielding gas, changes from 5% to 5%, the metal transfer mode changes from pulsed spray streaming transfer to pulsed projected spray transfer, while it remains the pulsed spray streaming transfer when 2% to 10% O 2 is added. Both CO 2 and O 2 are favorable to stabilizing arc and welding process. O 2 is even more effective than CO 2 . However, O 2 is more likely to cause the inclusion defects in the weld, while CO 2 can improve the weld appearance in some sense. The weld surface concavity, which is sensitive to the formation of lack-of-fusion defect in NG-GMAW, is greatly influenced by the addition of active gas, but the weld width and weld penetration almost keep constant.

A Way to Weld Sheet Metal with Double-Electrode GMAW

2013 ◽  
Vol 651 ◽  
pp. 333-337 ◽  
Author(s):  
Guo Hong Ma ◽  
Yu Ming Zhang
Keyword(s):  
Arc Welding ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
Metal Transfer ◽  
Constant Current ◽  
Spray Transfer ◽  
Metal Arc Welding ◽  
Globular Transfer ◽  
Double Electrode ◽  
Welding System

This paper designed a double-electrode GMAW(gas metal arc welding) system. This system includes main arc and bypass arc. Main arc (Base metal current: Ibm) is supplied with Constant Current power (CC mode) and bypass arc (bypass current: Ibp) is Constant Voltage power (CV mode). Main arc electrode used common carbon wire, bypass arc electrode used water cool copper. Welding experiment shows this DE-GMAW can change common metal transfer into spray transfer with lowest critical total current (Itotal) 200 amps. When Ibm decreases and bypass voltage increases, this critical current will increase and it is less than 230 amps when keeping spray transfer. High speed video proved that metal transfer is changed from spray transfer to globular transfer.

scholarly journals Droplet Transfer Induced Keyhole Fluctuation and Its Influence Regulation on Porosity Rate during Hybrid Laser Arc Welding of Aluminum Alloys

Metals ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1510
Author(s):  
Leilei Wang ◽  
Yanqiu Zhao ◽  
Yue Li ◽  
Xiaohong Zhan
Keyword(s):  
Aluminum Alloys ◽  
Weld Pool ◽  
Arc Welding ◽  
High Speed ◽  
Welding Current ◽  
Droplet Transfer ◽  
High Speed Imaging ◽  
Hybrid Laser Arc Welding ◽  
Globular Transfer ◽  
Weld Porosity

Hybrid laser arc welding (HLAW) features advantages such as higher welding speed and gap tolerance as well as smaller welding deformation and heat-affected zone than arc welding. Porosity in hybrid laser arc weld due to keyhole fluctuation tends to be the initial source of crack propagation, which will significantly diminish the weld performance. A high-speed imaging technique was adopted to record and analyze the droplet transfer and keyhole fluctuation behavior during hybrid laser arc welding of aluminum alloys. A heat transfer and fluid flow model of HLAW was established and validated for a perspective of the evolution process of droplet transfer and keyhole fluctuation. The relationship between keyhole fluctuation and weld porosity was also revealed. During the droplet transfer stage, liquid metal on the top surface of the weld pool flows toward the keyhole originated by globular transfer, and the keyhole fluctuates and decreases significantly, which has a higher tendency to form a bubble in the weld pool. The bubble evolves into porosity once trapped in the mush-zone near the trailing edge of the weld pool. Therefore, globular transfer during HLAW is the principal origin of keyhole fluctuation and weld porosity. Welding current has a significant influence on keyhole fluctuation and weld porosity rate. Droplet transfer frequency, keyhole fluctuation, and porosity rate increase with higher welding current under the globular transfer mode. The porosity rate shows a nearly positive correlation with the standard deviation of keyhole fluctuation.

Effect of Arc Length on Weld Appearance and Metal Transfer in Twin-Wire GMAW Process

2012 ◽  
Vol 472-475 ◽  
pp. 1279-1282 ◽  
Author(s):  
Huan Ming Chen ◽  
Shao Jie Wu
Keyword(s):  
Transfer Process ◽  
Arc Welding ◽  
High Speed ◽  
Metal Transfer ◽  
High Speed Camera ◽  
Arc Length ◽  
Process Stability ◽  
Spray Transfer ◽  
Weld Appearance ◽  
Globular Transfer

The experiments were performed with the twin-wire GMAW machine of Fronius product. The metal transfer process and the arc shapes were observed by use of shadowgraph technique with a high-speed camera. When the arc length increases during twin-wire CO2 arc welding, the mode of metal transfer changes from short-circuiting transfer to globular transfer, and to spray transfer. But it is difficult to form a stable spray transfer process, and the weld appearance becomes worse. The short-circuiting transfer in twin-wire CO2 arc welding can improve the process stability.

Droplet transfer behavior of narrow gap laser wire filling welding

2019 ◽  
Vol 33 (01n03) ◽  
pp. 1940045 ◽  
Author(s):  
Z. Zhang ◽  
R. Wang ◽  
G. Gou ◽  
H. Chen ◽  
W. Gao
Keyword(s):  
Welding Speed ◽  
High Speed ◽  
Transition Period ◽  
High Speed Photography ◽  
Narrow Gap ◽  
Droplet Transfer ◽  
Transfer Behavior ◽  
Feeding Speed ◽  
Wire Feeding ◽  
Droplet Transition

In this paper, we study the droplet transition behavior of narrow gap laser wire filling welding under the condition of changing welding speed and wire feeding speed, and it was observed by high-speed photography. It was found that with the increase of welding speed, the frequency of droplet transfer was reduced and the transition period was prolonged. With the increase of wire feeding speed, the wire was not fully melted and finally inserted into the molten pool.

Mechanically assisted droplet transfer process in gas metal arc welding

2002 ◽  
Vol 216 (4) ◽  
pp. 555-564 ◽  
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.

scholarly journals Diffuse Coplanar Surface Barrier Discharge in Artificial Air: Statistical Behaviour of Microdischarges

2014 ◽  
Vol 13 (1) ◽  
Author(s):  
Jan Čech ◽  
Jana Hanusová ◽  
Pavel Sťahel ◽  
Mirko Černák
Keyword(s):  
High Speed ◽  
Barrier Discharge ◽  
Atmospheric Pressure Plasma ◽  
Input Voltage ◽  
Half Period ◽  
Surface Barrier ◽  
Electrical Measurements ◽  
Large Area ◽  
Electrode Gap ◽  
Surface Barrier Discharge

AbstractDiffuse Coplanar Surface Barrier Discharge (DCSBD) is a novel type of atmospheric-pressure plasma source developed for high-speed large-area surface plasma treatments. The statistical behavior of microdischarges of DCSBD generated in artificial air atmosphere was studied using time-correlated optical and electrical measurements. Changes in behavior of microdischarges are shown for various electrode gap widths and input voltage amplitudes. They are discussed in the light of correlation of the number of microdischarges and the number of unique microdischarges’ paths per discharge event.The ‘memory effect’ was observed in the behavior of microdischarges and it manifests itself in a significant number of microdischarges reusing the path of microdischarges from previous half-period. Surprisingly this phenomenon was observed even for microdischarges of the same half-period of the discharge, where mechanisms other than charge deposition have to be involved. The phenomenon of discharge paths reuse is most pronounced for wide electrode

Metal Transfer in Double-Electrode Gas Metal Arc Welding

2007 ◽  
Vol 129 (6) ◽  
pp. 991-999 ◽  
Author(s):  
Kehai Li ◽  
YuMing Zhang
Keyword(s):  
Base Metal ◽  
Arc Welding ◽  
High Speed ◽  
Gas Metal Arc Welding ◽  
High Melting ◽  
High Productivity ◽  
Spray Transfer ◽  
Metal Arc Welding ◽  
Double Electrode ◽  
Melting Current

Gas metal arc welding (GMAW) is the most widely used process for metal joining because of its high productivity and good quality, but analysis shows that the fundamental characteristic restricts conventional GMAW from further increasing the welding productivity. A novel GMAW process, refereed to as double-electrode GMAW or DE-GMAW, thus has been developed to make it possible to increase the melting current while the base metal current can still be controlled at a desired level. This fundamental change provides an effective method to allow manufacturers to use high melting currents to achieve high melting speed and low base metal heat input. A series of experiments have been conducted to uncover the basic characteristics of this novel process. Results obtained from analyses of high-speed image sequences and recorded current signals suggest that DE-GMAW can lower the critical current for achieving the desired spray transfer, shift the droplet trajectory, reduce the diameter of the droplet, and increase the speed and (generation) rate of the droplets.

Droplet Transfer on Three Phase Relations at Four-Wire Welding Robot

2012 ◽  
Vol 588-589 ◽  
pp. 1751-1754
Author(s):  
Sheng Mian Xie ◽  
Bi Liang Zhong ◽  
Kai Yuan Wu ◽  
Yuan Mei Wen
Keyword(s):  
Phase Relation ◽  
High Speed ◽  
Phase Relations ◽  
Welding Parameters ◽  
High Speed Photography ◽  
Welding Robot ◽  
Droplet Transfer ◽  
Shielded Metal Arc Welding ◽  
Welding Seam ◽  
Metal Arc Welding

Based on the high-speed photography, the effect of phase relations on droplet transfer and welding seam was analyzed. To each TCGMAW (Twin-wire Co-pool Gas-shielded Metal Arc Welding) torch at four-wire welding robot, under the descriptive welding parameters, when the phase relation of the front wire and the back wire was alternate, the arcs of the two wires had no effect on each other basically; the welding seam shaped very well. When the phase relation was synchronized, the arcs attracted each other and the two arcs centralized to the middle of the two wires; the humping bead was formed. When the phase relation was random, now and then the arcs synchronized and attracted each other, and at times the arcs changed alternately and had no effect on each other; the appearance quality of the welding seam was moderate.

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