Research On The Improvement Of Pulse Power Supply For Electrolytic In-process Dressing

With the development of science and technology,hard-brittle materials are more and more widely used.Ultra-precision manufacture technology of these materials is still under research. Electrolytic In-process Dressing(ELID) is an effective mirror grinding technology,to which high importance has been attached for its bright future.In ELID grinding process,the passivation layer has a significant influence in the manufacturing quality and effeciency.For troditional grinding, the active balance of electrolyzing and the restraint for electrolyzing from film is self-adaptive process.Since the passivation layer changes with the factors such as the state of the surface of the grinding wheel,the charactors of the grinding liquid and grinding parameters,it is impossible to produce the ideal film for each different grinding process.Our laboratory came out with the intermittent electrolyzing control strategy for ELID grinding.First we decide a ideal scope for the passivation layer according to the grinding process,then in the grinding process the passivation layer is surveyed by a computer,after comparing the survey result and the fixed value,we can change the electrolytic parameters in order to adapt the electrolytic intensity,so we can control the passivation layer in the range we defined previously.In order to realize the real-time control of the parameters of the pulse power supply by computer,two pulse generation boards which can produce PWM(Pulse Width Modulation) pulse are used to replace the pulse-controlling part of the original power supply HDMD-IV.By programming the programable counter 8254 on the pulse board,we can get two PWM pulses with different cycles.Then the two pulse are sent to a and gate,and the output pulse is used to control the Power MOSFET through a driving circuit.When the PWM pulse with a larger cycle is at its low level,there is no output from the power supply,and when it is at its high level,we can get a pulse output which is synchronous with the PWM pulse with a smaller cycle.So we can adapt the parameters of the pulse power supply by changing the parameters of the two PWM pulses which are produced by the pulse boards.I also tried to realize the computer control of the voltage amplitude of the output pulse.Usability and stability of the improved power supply has been tested by practical ELID grinding experiments.