| 摘要 |
To realize an apparatus for automatically controlling heat input by a high-frequency power supply used for welding seal welded pipes of high quality, by detecting variation of the output frequency (f(i)) of a high-frequency power supply (1) for high-frequency welding of a steel pipe (7), finding a maximum value and a minimum value of outputs as a result of detecting the variation of the output frequency, finding a width ( DELTA f) of frequency variation as a difference between the maximum value and the minimum value, finding a desired width ( DELTA f(T)) of frequency variation, and so controlling the output of the high-frequency power supply (1) that the width ( DELTA f) of frequency variation is equal to the desired width ( DELTA f(T)) of frequency variation. |
