姓名：陳依剛
學號：m97r0211
日期：２００９／６／9
content
Abstract
 Introduction
 Experimental results
 Conclusions

Abstract
This describes improvement of the machining
characteristics of dry electrical discharge
machining (dryEDM) by controlling the
discharge gap distance using a piezoelectric
actuator.
INTRODUCTION
Dry electrical discharge machining (dry EDM)
is a new process which uses gas instead of
liquid as the dielectric fluid.
 Dry EDM is characterized by small tool
electrode wear, negligible damage generated
on the machined surface


Figure 1 shows the high frequency
response servo-feed system which was
newly developed for dry milling EDM by
one of the authors . To raise the
frequency response of the servo-feed
system, a piezoelectric actuator is
installed on the working table to adjust
the working gap distance.
HIGH FREQUENCY RESPONSE SERVOFEED SYSTEM
DRY EDM SIMULATION
Discharge delay time
Effect of piezoelectric servo in
experiment
Experimental results

The horizontal axis indicates the gain of the
driver for the piezoelectric actuator. Zero gain
means that machining was performed using the
Z-axis servo only, without using the piezoelectric
servo system. In this case, the probability of
short circuiting reached 95%. With increasing
gain of the driver for the piezoelectric actuator,
the probability of short circuiting decreases,
resulting in considerable increase of
the
material removal rate.
Simulation of time variation of gap distance
without piezoelectric servo system
Time variation of gap distance with
piezoelectric servo.
CONCLUSIONS
 A piezoelectric
servo system was
developed to improve the frequency
response of the gap control in dry EDM.
 In that the use of the piezoelectric
servo system stabilizes the gap control
resulting in the considerable increase
of the material removal rate of dry
EDM
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