变极性电弧焊接的电流换向过程影响因素试验研究

Experimental research on factors influencing the current commutation process of variable-polarity arc welding

  • 摘要: 采用基于反向再燃弧电压产生电路的变极性焊接电源为试验平台,研究了电源设备及其控制参数、焊接回路电缆寄生电感和焊接工艺参数对变极性焊接电流换向过程的影响规律. 试验结果表明,提高反向再燃弧电压值能够提升变极性过程的电流变化速率,而较大的焊接回路电缆寄生电感会降低电流变化速率,同时降低变极性结束时的电流值,不利于变极性过程的电弧可靠再引燃和稳定燃烧. 初始焊接电流越小,则变极性过程结束时的电流值越小,增加共同导通时间可以提高变极性结束时的电流值,但同时降低变极性开始时的电流大小. 因此小电流变极性焊接时可采用较大的反向稳压值并适当增加共同导通时间,以增强变极性过程中的电弧稳定性.

     

    Abstract: In the current inversion process of variable-polarity arc welding of aluminum alloy, drastic changes in electron and ion concentrations in arc space may lead to the failure of current commutation and arc reignition, thus affecting the arc burning stability and weld formation quality. The novel reverse arc reignition voltage-generating circuit will produce a stable reverse voltage during the current polarity inversion process. In this circuit, the value of the reverse voltage remains unchanged with the variation in the base welding current, and thus can better meet the requirement of reverse arc reignition voltage for current inversion. Through the use of the variablepolarity welding power supply with novel reverse arc reignition voltage-generating circuit as the experimental platform, the influence of the power equipment and its control parameters, the parasitic inductance of the cable in the output welding loop, and the welding process parameters on the current commutation process of variable-polarity arc welding was investigated. The experimental results show that increasing the value of the reverse arc reignition voltage can increase the current variation rate in the polarity inversion process. Contrastingly, a large parasitic inductance of the cable in the output welding loop will reduce the current variation rate and the current value at the end of the polarity inversion process, which is detrimental by the reliable arc reignition and stable arc burning in the polarity inversion process. The lower the initial welding current is, the lower the current value at the end of the polarity inversion process. Increasing the common conduction time can increase the current value at the end of the polarity inversion process, but decrease the current value at the beginning of this process. Therefore, to improve the arc stability in the polarity inversion process, a large value of the reverse arc reignition voltage and an appropriate increase in common conduction time can be used in low-current variable-polarity welding. All of the conclusions previously presented can provide reference and basis for the selection and adjustmentof the power equipment and its control parameters for variable-polarity arc welding under various process parameters.

     

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