| 摘要 |
PURPOSE:To realize monitoring the quality of an arc welded zone without being influenced by even fluctuation of the average voltage by extracting a low-frequency component and a high-frequency component from a waveform of the arc voltage measured between an electrode and objects to be welded to appraise and monitor a welding state from a ratio of these two components. CONSTITUTION:The arc voltage V generated between the electrode 3 and a steel pipe 1 is inputted to a measurement circuit 4 and a DC part is eliminated by an isolator 6 and afterward, the low-frequency component and the high-frequency component in an AC part are extracted by filters 7a and 7b. The extracted respective components are inputted to computing elements 9a and 9b via rectifiers 8a and 8b and the sizes of the respective frequency components are quantified as overall values or peak values. Further, the ratio K=P/Q of the high-frequency component P to the low-frequency component Q is calculated by a discriminator 16 and displayed on a display device 17 and a value of K is monitored, by which the welding state is appraised. By this method, the quality of the arc welded zone without being influenced by even the fluctuation of the average voltage is monitored.
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