JPS57202975A - Arc welding machine - Google Patents

Abstract

PURPOSE:To melt the coasting part of a consumable electrode effectively and to prevent the formation of a spherical mass at the leading end by regulating the output voltage of a welding electric power source lower than that during welding and switching the same to the pulse-like outputs of a crest value in the stage of ending the welding. CONSTITUTION:When the under-welding signal from a starting circuit 13 is annihilated at the time (b), a motor rotating speed control circuit 18 interrupts the output and a motor 20 is decelerated quickly and stops after the time DELTAt. On the other hand, a switching circuit 9 changes over to transmit the output of the 2nd reference voltage setter 8. Time limit circuits 14, 15 start timing. At the time t2 when the circuit 15 times out, the low voltage E2 of the setter 8 is supplied and during the set time t3 of the circuit 16 in succession to this, a switching circuit 11 supplies the output of a reference voltage setter 10 to a switch 12. Therefore, a welding electric power source 1 outputs a high voltage Ep during that time. Following to this, the power source 1 output returns again to the voltage E2 and during the time t1 when the circuit 14 times out, the voltage E2 is continued.