| The rapid development of modern information technology advances the controlsystem of the digital arc welding power supply intelligent more and more, and it is aninevitable trend of the continuous development of the arc welding power source. Onaccount of the increasing complexity of modern welding conditions and the progressof welding process control, the requirements of control functions and the expertdatabase system of welding machines are also enhanced continually, in particular,materials to weld difficultly, such as aluminum alloy, are widely used, performancerequirements of welding machine control are higher and more specific.Based on the power supply design thought for DSP and ARM to control digitally, inallusion to characters of difficult welding of lightweight materials which are usedmore and more widly, such as aluminum alloy, this paper advanced a new typecurrent waveform control methodology of the sinusoid modulation pulse MIGwelding, and hereby developed the welding process control of aluminum alloy and itsexpert database system, in order to establish a new type of intelligent arc weldingpower supply to meet the higher and more specific requirement of difficult welding oflightweight materials.This article advanced a new current waveform parameter design principle of thesinusoid modulation pulse MIG welding, and systematically established the universalmathematical model of the parameter computation of the sinusoid modulation pulse,making that the welding energy input can be effectively controlled and preciselyregulated, the transition of pulse change is smooth and the welding process is stableand reliable. With the characteristics of sinusoidal waveform, such as infinitederivative continuity, eternal periodicity and limited control parameters, this articleestablished the theoretical foundation for exactitude matching, unification andoptimization of the parameters in the new sinusoid modulation pulse MIG weldingprocess. Bead-on-plate overlay welding was carried out on the pure aluminum sheettest sample for the test. The result indicated that during the welding process, theinstantaneous current waveform is stable and clear, the instant waveforms of both thecorresponding voltage and the welding energy are very stable, the repeatability of theU-I graph is good and its family of lines is clear and its distribution is concentrated,showing that the welding process is stable and the neat and high quality ripple weld seam may be produced.Based on the difficulties in welding of light material like aluminum alloy, such aslow energy supply and other requirements, this article established the controlparameter relationship formulas in sinusoid modulation pulse MIG welding aluminum,achieving that the welding energy can be regulated effectively and precisely. And theexperiments validated the correctness and practicability of the control parameterrelationship formulas established by using sinusoid modulation pulse, and that thestable and high quality fish scale welding seams were attained easily. Theexperiments indicated that while the change range of values of the density coefficientm in the relationship formula is from2to3, there are advantages such as widerparameters matching range and less interference from external welding environmentalfactors in sinusoid modulation pulse MIG welding, and it has set the theoreticalfoundation for the parameter unification exploitation in the sinusoid modulation pulseMIG welding process.This article deduced the simplified formulas to describe the sinusoidal swingparameters in the aluminum welding with sinusoid modulation pulse MIG welding.Then, some experiments carried out validated the correctness of the formulas, andthat ideal fish-scale welding seams are easily and stably formed. Experimental resultsindicate, when k is in the duration of [15.0%,23.1%], the sinusoid modulation pulseMIG welding is of wide parameter matching range, low parameter requirement, largerstable working region and low sensitivity to external interference.On problems of the stability, control parameter optimization and robustness inaluminum alloy welding, especially on difficulties that aluminum alloy sheets is veryeasy perforation in welding process, by introducing the decrease energy coefficientk t, sinusoid current swing coefficient k AI and time swing coefficient k At, this articlerespectively established the universal relationship formulas of parameters in themonopulse MIG welding and the symmetry sinusoid modulation pulse MIG welding.And processing1mm aluminum alloy sheet welding tests respectively validated theirfeasibility. The test contrast validated that the sinusoid modulation pulse MIGwelding is of large welding parameter working confine, good robustness, easy controland steadily producing ideal ripple weld seams.Furthermore, by introducing the time swing coefficient k At, current swing coefficientk AI and decrease energy coefficient k t, and decrease energy coefficient k tqin dense pulses, decrease energy coefficient k trin sparse pulses andcurrent increase coefficient k I, this article respectively established the universalrelationship formulas of parameters in the double-pulsed MIG welding and thedissymmetry sinusoid modulation pulse MIG welding. And processing1mmaluminum alloy sheet welding tests respectively validated their feasibility. The testcontrast validated that parameters of the double-pulsed MIG welding are chosereferring to parameters of the dissymmetry sinusoid modulation pulse MIG welding,but the dissymmetry sinusoid modulation pulse MIG welding is more advantage.In summary, by introducing the energy coefficient k t, the swing coefficient k A, thepulse number n in per negative half periods of sinusoid, the most average I aof currentpulses and the least welding current (i.e. maintaining arc current) I m, this articleestablished the universal mathematical models of parameters in the sinusoidmodulation pulse MIG welding, and by using orthogonal test to optimize and matchthe parameters, built the expert database system in sinusoid modulation pulse MIGwelding based on the mathematical models. And processing aluminum alloy weldingtests validated validated the advantages of large welding parameter working confine,good robustness, easy control, etc. in the sinusoid modulation pulse MIG welding.And these provide a new theory and test foundation on developing of digital highperformance welding machines equipped the expert database.
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