| 摘要 |
1468198 Automatic control of arc welding AIR PRODUCTS & CHEMICALS Inc 3 July 1974 [11 July 1973] 29545/74 Heading G3R In a DC arc system, the volt-ampere characteristic is regulated by measuring the arc current and voltage and summing corresponding signals with a reference signal to form a power supply control signal. The proportions of current and voltage feedback are simultaneously adjustable to give continuous control between constant current and constant voltage modes of operation. As shown, a welding arc 26 is produced by a three-phase source 11, transformer 12, and controlled rectifiers 14. The arc current and voltage are measured by feedback units 45, 46 each including a potentiometer, the movable contacts of which are ganged together so that the relative amounts of current and voltage feedback to an amplifier 42 are simultaneously adjustable. The amplifier 42 also receives a set reference voltage from a circuit 40, and supplies control signals through a PI regulating amplifier 52 to a firing circuit 55 for the rectifiers 14. A circuit 53, for ensuring the supply of increased power when the arc is first established, includes a relay supplied by a switching transistor and controlling contacts in a feedback path of the amplifier (52), Fig. 3 (not shown). |
