| 摘要 |
PURPOSE:To prevent melt sticking of a W electrode and deposited metal or the groove surfaces of base materials that takes place during welding in an automatic TIG welding device by so controlling the device as to stop the welding when the arc voltage value during welding attains a correct value or below. CONSTITUTION:When a switch 7 is turned on, a relay 9 is energized, and A contacts 9a close. Since B contacts 10a are held closed, the relay 9 latches itself and welding is started. On energizing of the relay 9, a timer 10 starts operating and the contacts 10a open in a constant time after arc generation. When the arc is generated between an electrode 2 and base materials 3, the output relay 6 of a comparator 4 goes off, and the B contacts 6a thereof close, thereby keeping the relay 9 latched on. The arc voltage Va and the correct arc voltage VRef of a lower limit voltage setter 5 are compared by the comparator 4, and when Va>VRef, the relay 6 turns off and the relay 9 turns on, thus the welding is continued. When Va<VRef on account of certain disturbance, a signal is outputted from the comparator 4, and the relay 6 turns on, the contacts 6a open and the relay 9 turns off, whereby the welding is stopped. |
