| 摘要 |
PURPOSE:To obtain a titled welding machine that can maintain good spray transfer and obtain good results of welding by detecting a rising time of pulse current, comparing it with a set value and feedback-controlling the ignition angle of thyristor of a rectifier circuit. CONSTITUTION:In a pulse arc welding machine that converts the secondary side output of a three-phase transformer 10 connected to an AC power source to DC by a thyristor for three-phase rectification, smoothens it by a capacitor 14, switching it by a transistor 16 and a driving circuit 18 and supplies a welding current of pulse waveform to arc load 26, rising time is detected by a pulse rising time detector 30 basing on output of a shunt 24 that detects the welding current. The detected value is inputted to a comparator 34 and compared with a set value of a target rising time outputted by a setting device 32. The comparison output of the comparator 32 is inputted to a thyristor ignition angle setting circuit 36. The ignition angle of each thyristor of thyristor stack 28 is feedback-controlled by this input to make the detected value coincident with the set value. |
