| 摘要 |
PURPOSE:To prevent lack of penetration in the weld zones of base materials by increasing the quantity of electric charge at the start of welding. CONSTITUTION:A relay is operated by depressing an on-button, and relay contacts 213 conduct. Then, a differential circuit is constituted of a capacitor 30 and a variable resistor 31, and at the point of the time when the contacts 213 go on, the voltage at the point S is the DC voltage of an electric power source 29, and attenuates at the time constant determined by the capacity of the capacitor 30 and the resistance value of a variable resistor 31 until said voltage is made zero. The voltage at the point S and the output voltage of a pulse width regulating circuit 16 are synthesized by a DC amplifier 32, whereby the pulse width in an arc period is increased at the starting of welding and the pulse width is decreased gradually according to the time constants of the differential circuit. After the time when the welding goes steady, the pulse width in the arc period is specified pulse width. |
