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Variable Polarity Plasma Arc Flat Position Welding Process of Thin Plate Aluminum Alloy

Author: SongCheng
Tutor: HanYongQuan
School: Inner Mongolia University of Technology
Course: Materials Processing Engineering
Keywords: Aluminum alloy Variable polarity plasma arc Weld
CLC: TG457.14
Type: Master's thesis
Year: 2009
Downloads: 169
Quote: 0
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Abstract


Aluminum alloy of variable polarity plasma arc welding method compared with other fusion welding methods, with energy concentrated arc stiffness, a large penetration depth, small deformation after welding characteristics, can be realized in the case without groove side welding, welding production on the space shuttle external tank and other products, has a wide application prospect welding method has been successfully applied. This article used in the experiment equipment including variable polarity plasma arc welding power source, plasma arc torch, wire feed system, cooling system, semi-automatic welding carriage, arc force sensor, and the Hanover welding quality analyzer. Welding the main power through dual inverter technology, the output constant current external characteristic. One inverter control circuit to control the main power IGBT driver jointly controlled by PWM (fixed frequency modulation pulse width) and PFM (fixed pulse width modulation frequency); second inverter to 80C196KC microcontroller to control the core, the output pole-changing Sexual current. Positive and negative polarity current amplitude and the positive and negative polarity time ratio and other parameters can be adjusted independently by the microcontroller program. Aluminum alloy sheet using a variable polarity plasma arc the flat welding process test, analysis of the impact of variable polarity plasma welding process of welding current, plasma gas flow, wire feed speed and welding parameters on weld aluminum VPPA The welding process welding current is a key factor to affect the weld. Plasma gas flow plasma arc force and arc voltage. Wire feed speed, tungsten within shrinkage, nozzle diameter and welding speed, welding parameters forming have a major impact on the stability of the existence of the molten pool and weld these parameters any parameter change will weld pool thermal and mechanical The balance of impact. Real-time to maintain the molten pool on the \An important prerequisite for reasonable parameters and control measures, to establish a stable molten pool, good weld. After a large number of tests drawn 3mm thick aluminum alloy specimens VPPA welding parameters: positive polarity current 84A, reverse polarity current 110A, plasma gas flow 3L/min 176cm/min wire feed speed, welding speed 35cm/min, tungsten shrinkage within a very 2mm. Analysis of the mechanical properties of variable polarity plasma arc and sheet aluminum VPPA weld stability. Were tested on the the VPPA welding, welding current, plasma gas flow plasma arc welding parameters on force law, provides a theoretical basis for the the sheet aluminum VPPA welding parameter selection. Analyzed as the current increases, the center of the arc plasma pressure increases slightly less than the current multiples to increase the value of the square of the multiples of plasma gas flow and plasma arc pressure substantially proportional relationship. Using Hanover welding quality analyzer real time recording and analysis of the variation of the welding process, the reverse polarity of current and voltage parameters of the welding current, voltage, voltage probability density and current probability density. Testing the mechanical properties of aluminum welded joints to observe the microstructure of the weld. The VPPA quality of welded joints of aluminum alloy comprehensive assessment. Analyzes aluminum alloy the VPPA welded joints mechanical performance is good, basically the same as the base metal, weld microstructure dense, nonporous inclusions and other defects.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Welding, metal cutting and metal bonding > Welding process > Welding of a variety of metal materials and components > Welding of metallic materials > Aluminum
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