| 摘要 |
PURPOSE:To eliminate the necessity of installing a number of DC power sources by permitting the voltage to be finely controlled only by selecting the resistors and transistors in a variable impedance circuit connected in parallel to a constant-voltage apparatus, in a pulse power source apparatus for electric discharge machining. CONSTITUTION:When the voltage applied onto a working gap shifts to the ON- time operation, control pulses S4 and S5 are generated, and transistors 60 and 64 are set OFF. Therefore, when the output current value of a constant-current apparatus 52 is kept constant, and prescribed values of resistors 66 and 70 are selected, the synthesized resistance of a variable impedance circuit 58 becomes equal to the parallel resistance value of the resistors 66 and 70. As also S6 is set OFF in the next section, the resistance value of the variable impedance circuit 58 becomes equal to that of the resistor 70, and the voltage corresponding to said resistance value is selected. |
