Prediction Model of Droplet Size in Low-Current GMAW

2013 ◽  
Vol 652-654 ◽  
pp. 2299-2302
Author(s):  
Jun Xiao ◽  
Guang Jun Zhang
Keyword(s):  
Prediction Model ◽  
Droplet Size ◽  
High Speed ◽  
Welding Current ◽  
Experimental System ◽  
Metal Transfer ◽  
Constant Current ◽  
Future Research ◽  
Feed System ◽  
Globular Transfer

A low-current GMAW experimental system is established using a constant current power supply and a controlled wire feed system. The metal transfer behavior and the droplet growing process in low-current GMAW are investigated by using a high-speed camera, and the welding current and voltage are monitored by a data acquisition set. The metal transfer in low-current GMAW can be classified into three modes: short-circuiting transfer, long-arc short-circuiting transfer and large globular transfer. The arc voltage is the primary factor that affects the metal transfer mode. The droplets growing in low-current GMAW are observed and analyzed. The maximum detaching size of the droplet and the corresponding growing time with different welding current are calculated from the recorded image sequences of metal transfer. Based on such results, a prediction model of the droplet size is thus established, which will be used in the future research on pulsed laser-enhanced GMAW.

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.

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

2013 ◽  
Vol 718-720 ◽  
pp. 202-208 ◽  
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.

Study on Metal Transfer and Welding Spatter Characteristics of Basic Flux Cored Wire

2013 ◽  
Vol 477-478 ◽  
pp. 1369-1372 ◽  
Author(s):  
Yong Wang ◽  
Ying Qiao Zhang ◽  
Bao Wang ◽  
Zhi Jun Wang
Keyword(s):  
High Speed ◽  
Short Circuit ◽  
Welding Current ◽  
Metal Transfer ◽  
Welding Parameters ◽  
Droplet Transfer ◽  
Cored Wire ◽  
Basic Flux ◽  
Key Factor ◽  
Slag Column

The metal transfer behaviors of basic flux cored wire at different arc voltage and welding current and the resultant welding spatter were investigated by using a high speed camera. Two modes of metal transfer are found: globular repelled transfer (lower welding parameters) and small droplet transfer (higher welding parameters). The former is accompanied by large granular spatter, large droplet itself explosion spatter and electric explosive spatter of short-circuit, and spatter in the latter is reduced obviously. But if the slag column is found in the two models, spatter could be dropped evidently owing to its significant guiding role for metal transfer. Therefore the slag column is the key factor of reducing welding spatter.

Effect of Laser Beam on Double Wire Pulsed MIG Welding Process

2011 ◽  
Vol 130-134 ◽  
pp. 4169-4173
Author(s):  
Li Yan Lou ◽  
Huan Li ◽  
Xu You Wang ◽  
Wei Wang ◽  
Ying Gao
Keyword(s):  
Laser Beam ◽  
High Speed ◽  
Welding Process ◽  
Welding Current ◽  
Metal Transfer ◽  
Wave Form ◽  
Hybrid Welding ◽  
Transfer Mode ◽  
Metal Transfer Mode ◽  
Set Up

Based on the coupling of laser beam and double arcs, a novel process was investigated. This research set up the laser-double wire pulsed MIG hybrid welding system. Meanwhile the current and voltage sensors were used to detect welding current and arc voltage wave-form and high-speed videography system was used to observe the metal transfer process and arc behavior. The three signals were acquired synchronously. The results showed that the synergic action of the three different heat sources leads to a change in metal transfer mode. It was revealed that the metal transfer mode was two droplets per pulse in laser-double wire hybrid welding process while one droplet per pulse in double wire welding process with the same certain experiment parameters. And we also discovered that the arcs were attracted strongly by the laser beam.

scholarly journals The Effect of the Use of PTFE as a Covered-Electrode Binder on Metal Transfer

2015 ◽  
Vol 20 (2) ◽  
pp. 160-170 ◽  
Author(s):  
Cláudio Turani Vaz ◽  
Alexandre Queiroz Bracarense
Keyword(s):  
High Speed ◽  
Short Circuit ◽  
Welding Current ◽  
Metal Transfer ◽  
Outer Edge ◽  
Polymer Binder ◽  
Electrode Binder ◽  
Covered Electrodes ◽  
Weld Metal Microstructure ◽  
Metal Microstructure

AbstractStudies have shown that when used as binders for basic covered electrodes, polymers produce a weld metal microstructure with a high acicular ferrite content. The reasons identified for this behavior include changes in the shielding atmosphere and metal transfer mode. To investigate the effect of polymers on metal transfer, voltage oscillograms and high-speed films were recorded during welding with standard-binder and polymer-binder E7018 electrodes using different welding currents. Electrodes tips collected after the arc had been abruptly interrupted were examined metallographically. For electrodes with a polymer binder, the short-circuit frequency was lower regardless of the welding current used and decreased as welding current increased. In many events characterized as short circuits in the voltage oscillograms for polymer-binder electrodes, metal transfer in fact occurred without any arc interruption. The angle between the outer edge of the metal drop and the inner edge of the coating crater showed that the polymer increased the intensity of the plasma jet, and the pinch effect observed during welding using the polymer-binder electrode indicated that there were changes in surface tension and electromagnetic force.

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.

Research on High-Speed Cutting of Cr12MoV Hardened Steel - A Review

2020 ◽  
Vol 15 ◽  
Author(s):  
Fei Sun ◽  
Guohe Li ◽  
Qi Zhang ◽  
Meng Liu
Keyword(s):  
High Speed ◽  
Cutting Temperature ◽  
High Hardness ◽  
High Strength ◽  
Hardened Steel ◽  
Parameters Optimization ◽  
Future Research ◽  
High Speed Machining ◽  
Machined Surface ◽  
Stamping Die

: Cr12MoV hardened steel is widely used in the manufacturing of stamping die because of its high strength, high hardness, and good wear resistance. As a kind of mainstream cutting technology, high-speed machining has been applied in the machining of Cr12MoV hardened steel. Based on the review of a large number of literature, the development of high-speed machining of Cr12MoV hardened steel was summarized, including the research status of the saw-tooth chip, cutting force, cutting temperature, tool wear, machined surface quality, and parameters optimization. The problems that exist in the current research were discussed and the directions of future research were pointed out. It can promote the development of high-speed machining of Cr12MoV hardened steel.

Review of Research on Hydrostatic Bearings

2020 ◽  
Vol 13 ◽  
Author(s):  
Xiaodong Yu ◽  
Yu Wang ◽  
Junfeng Wang ◽  
Wenkai Zhou ◽  
Hongwei Bi ◽  
...  
Keyword(s):  
High Speed ◽  
Static Pressure ◽  
Development Trend ◽  
Cnc Machining ◽  
Pressure Effects ◽  
Cnc Machine Tools ◽  
Future Research ◽  
Theoretical Formula ◽  
Hydrostatic Bearing ◽  
Hydrostatic Bearings

Background: Hydrostatic bearings have the advantages of strong bearing capacity, good stability, small friction coefficient and long life. The performance of liquid hydrostatic bearings directly affect the accuracy and efficiency of CNC machining equipment. The performance is conducive to the development of CNC machine tools towards high speed and heavy load, so it is necessary to sort out and summarize the existing research results. Objective: This study summarizes the current development status of hydrostatic bearings and explains the development trend of hydrostatic bearings. Methods: According to the recently published journal articles and patents, the recent experimental research on hydrostatic thrust bearings is summarized. This paper summarizes many factors that affect the performance of hydrostatic bearings, and discusses the causes of various factors on hydrostatic bearings. Finally, future research on hydrostatic bearings is presented. Results: The study discusses experimental methods, simulation processes, and experimental results. Conclusion: This study can produce dynamic and static pressure effects by changing the structure of the oil cavity of the hydrostatic bearing. This effect can make up for the static pressure loss. By improving the theoretical formula and mathematical model and proposing a new simulation method, the accuracy of the hydrostatic bearing simulation is satisfied; the future development trend of the hydrostatic bearing is proposed.

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