Detection and Analysis of Weld Pool Oscillation Information for Variable Polarity Plasma Arc Welding

2015 ◽  
Vol 51 (20) ◽  
pp. 114
Author(s):  
Lan CHUN
Keyword(s):  
Weld Pool ◽  
Arc Welding ◽  
Plasma Arc Welding ◽  
Plasma Arc ◽  
Variable Polarity ◽  
Variable Polarity Plasma Arc

Experimental Analysis of Welding Parameters on Variable Polarity Plasma Arc Pressure

2013 ◽  
Vol 651 ◽  
pp. 355-360 ◽  
Author(s):  
Yi Jiang ◽  
Ming Liu ◽  
Yao Hui Lu ◽  
Bin Shi Xu
Keyword(s):  
Arc Welding ◽  
Gas Flow ◽  
Welding Current ◽  
Welding Parameters ◽  
Plasma Arc Welding ◽  
Plasma Arc ◽  
Arc Pressure ◽  
Variable Polarity ◽  
Reversed Polarity ◽  
Variable Polarity Plasma Arc

Variable polarity plasma arc welding has been widely used to manufacture industries. The effects of welding current and plasma gas flow as the most important parameters on variable polarity plasma arc pressure were discussed experimentally. To welding current, two experimental were designed to discuss the effects of straight polarity current and reversed polarity current on arc pressure respectively. It could be concluded that arc pressure is quadratic with welding current. To plasma gas flow, both experimental and numerical analysis are used to discuss the mechanisms of plasma gas flow to arc pressure, and it could be conclude that arc pressure is quadratic with plasma gas flow rather than linear.

Workpiece Cleaning During Variable Polarity Plasma Arc Welding of Aluminum

1994 ◽  
Vol 116 (4) ◽  
pp. 463-466 ◽  
Author(s):  
Q. Pang ◽  
T. Pang ◽  
J. C. McClure ◽  
A. C. Nunes
Keyword(s):  
Arc Welding ◽  
Dielectric Breakdown ◽  
Surface Preparation ◽  
Refractory Oxide ◽  
Plasma Arc Welding ◽  
Plasma Arc ◽  
Reverse Polarity ◽  
Variable Polarity ◽  
Variable Polarity Plasma Arc

Variable Polarity Plasma Arc welding has proved to be extremely successful in welding aluminum alloys despite their adherent refractory oxide. This success has been attributed to removal of the oxide during the reverse polarity cycle. In situ optical spectroscopy is used to measure the amount of hydrogen and oxygen in the plasma arc with a minimum detectable limit of less than 100 ppm. It was found that the amount of contamination is independent of surface preparation and torch speed. Using this information, it is proposed that the predominant mechanism for reverse polarity cleaning in aluminum is dielectric breakdown of the surface oxide ahead of the torch rather than by ion sputtering.

The Effect of Weld Gas Flow Rate on Al-Li Weldability

1993 ◽  
Vol 115 (3) ◽  
pp. 263-267
Author(s):  
L. F. Martinez ◽  
J. C. McClure ◽  
A. C. Nunes
Keyword(s):  
Flow Rate ◽  
Arc Welding ◽  
Gas Flow ◽  
Plasma Arc Welding ◽  
Plasma Arc ◽  
Gas Flow Rate ◽  
Welding Arc ◽  
Variable Polarity ◽  
Variable Polarity Plasma Arc

Adequate shield and plasma gas flow rate during plasma arc welding are crucial factors in achieving high quality welds. Too low a shield gas flow rate lets atmosphere enter into the arc and too high a rate wastes weld gas and may cause turbulence and entrain atmosphere. Sufficient plasma gas flow is required for keyhole welding and, as shown in this paper, can reduce hydrogen contamination in the weld. In-situ optical spectroscopy used to detect oxygen and hydrogen in the welding arc during variable polarity plasma arc (VPPA) welding of aluminum 2090 revealed that there is an easily detected critical shield gas flow rate needed to exclude atmosphere and that this critical rate can be used to automatically control gas flow rates during welding.

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