| 摘要 |
PURPOSE:To stabilize welding arcs and to prevent the generation of welding defects such as lack of penetration by stopping a welding head which is controlled of automatic running while a welding electric source is in a short circuited state or in a no-load state. CONSTITUTION:When the leading end of a welding wire is brought into contact with the surface of the groove of base materials and welding is started, a welding power source is short circuited and the detected voltage signal Vx of the welding voltage detected with a voltage divider 18 is roughly zero. Therefore, the signal Vx is not applied to the 2nd decision circuit 21, the contacts 16-1 of a relay 16 are opened and the welding head stops in the set position. When the welding arc extinguishes on account of a certain cause later, that is, when the welding power source is put in a no-load state, the output voltage increases and the signal Vx of the voltage divider 18 increases as well. When the signal Vx exceeds the permissible upper limit voltage, the circuit 21 stops transmission to the relay 16 and the motor stops. Therefore, the welding head stops in the welding position where the welding arc extinguishes. |
