| 摘要 |
PURPOSE:To control feeding of a welding wire with high accuracy by digitizing the detected number of revolutions of a feed motor for welding wire, comparing and operating the same with a motor revolution number set signal and feeding this back as a firing signal for a thyristor for motor control. CONSTITUTION:The number of revolutions of a welding wire feed motor 19 is detected with a detector 11, and after the detected output is amplified with an amplifier circuit 12, it is converted to a digital signal with a digital signal converter 13. This signal Bi is compared and operated with a motor revolution number set signal Ai in a comparing and operating circuit 14, and the result of the operation is inputted as a thyristor firing position instruction signal Si to a comparator 17. On the other hand, the output Ti synchronized with the lowest point of voltage of an electric power source 16 for motor from a time series clock pulse counter circuit 15 is put into the comparator 17, and when it concides with the signal Si, a signal Ci is outputted and is inputted to a gate circuit 18, the output whereof is supplied as a firing signal to the gate of a thyristor 20 for controlling the motor 19, whereby the number of revolutions of the motor 19 and the feed speed of the wire are controlled correctly. |
