| 摘要 |
1,241,959. Arc welding systems. BRITISH OXYGEN CO. 25 Nov., 1968 [19 Dec., 1967], No. 57563/67. Heading H2H. A system for A.C. arc welding comprises a main circuit for striking and energizing the arc, and an auxiliary circuit for applying a timed voltage pulse to the electrodes in order to reignite the arc after extinction. The latter includes a capacitor shunting a choke, and discharge of the capacitor may be controlled by a thyristor. In the arrangement shown in Fig. 1, the arc 12 is normally supplied through a main transformer 2 and a choke 6. When the arc extinguishes at a current zero, the voltage across the gap rises steeply and a pulse is applied through a second transformer 16 to the gate of a thyristor T. This allows a capacitor C1 to discharge through the choke 6 causing a high voltage pulse to flow and restart the arc. The capacitor C1 is charged through a transformer 4, bridge 14 and resistor R1, and is shunted by another capacitor C2 which absorbs the reverse voltage from the choke 6. This second capacitor C2 is discharged by a resistor R2. The arrangement is stated to be particularly suitable for argon-shielded arc welding of aluminium using a non-consumable electrode. |
