| 摘要 |
PURPOSE:To maintain the distance between a torch and the work constant, by converting the change in said distance to the change in the high frequency voltage between a detection conductor and the work and moving the torch vertically with the driving signal that changes in accordance with said change in the high frequency voltage. CONSTITUTION:An integration circuit 30 generates a DC voltage signal of a zero level or a positive or negative level according to whether the distance between a detection ring 10 and the work 3 is equal to a set length or is larger or smaller than the same. A circuit 31 for generating an ascending signal and a circuit 32 for generating a descending signal output the ascending or descending signal according to the output level of the circuit 30 and an upward driving circuit 33 or downward driving circuit 34 applies the upward or downward driving signal through respective speed regulators 35, 36 to a driving device 7. The device 7 drives a vertical moving holder 9 vertically according to the upward or downward driving signal to adjust the height of a torch 2 so that the distance between the ring 10 and the work 3 is maintained always at the set length. |
