| 摘要 |
<p>The appts. consists of a transformer feeding a rectifier bank with two d.c. output leads (a,b), one lead contg. a switch(c) followed by a free-wheel diode(d) connected across leads (a,b). Downstream of the diode(d) connection, lead(a) contains an inductance(e) and is then connected to a welding gun(f) together with lead(b). Switch(c) chops the d.c. to produce an intermediate current of high frequency, the duration of the interruptions to current flow being adjustable. Switch (c) is pref. a transistor or a thyristor; and the frequency of the chopped current is pref. 600 Hz. Good welds are obtd. over the entire range of stepless adjustment, so no transformer tapping are required and only a small and inexpensive inductance is required.</p> |
