英语翻译The experiments were performed on an electrical discharg

英语翻译The experiments were performed on an electrical discharge small hole machine DK730 (made in China,modified by author).The worktable of the machine was especially designed to accept an ultrasonic vibration unit,and the clamp of the machine was designed to accept high pressure gas when it turning.In experiments,the tool electrode was a cylindrical pipe with outer and inner diameters of 10 and 9 mm,respectively.The high pressure gas was supplied into working gap through internal hole of tool electrode.There was a gas drier between the compressor and the regula-tor to eliminate the influence of water vapor contained in the compressed gas on the machining characteristics.45# steel and copper were selected as workpiece and tool electrode,respectively.Air and oxygen gas were selected as gas mediums.The ultrasonic generator (made in China) had a maximumpower of 100W with an adjustable frequency in the rangeof 17–23 kHz.The measured amplitudes of vibration during idling were 0.006mm at 50W and 0.012mm at 100W.The frequency used in experiments was set at 20.3 kHz (controlled through the adjusting knob).The stress of the gas could be change continuously from 10 to 500 kPa.The voltage supplied by power supply could be changed by step of 20V from 100 to 300V.The MRR was measured using a dial gauge with an accuracy 0.001 mm.The rate of depth penetration was measured with a dial gauge and the MRR calculated by multiplying by the cross-sectional area of the penetrated aperture.The surface roughness is measured through a Talysurf 4_ surface measuring instrument (made in England) with a relative accuracy of five percent (5%).The transistor pulse generator power supply is now commonly employed as a UEDM power supplier.It transforms the AC supply from the mains and provides a rectangular voltage waveform as shown in Fig.2.The amount of material removed from the workpiece depends on the characteristics of the electrodischarge voltage,current and time.The current–time diagram is shown in Fig.3.The time interval between switching the generator on and off is as the pulse duration (ts) while the time interval between switching the generator off and on for the next pulse is the pulse interval (ti).The ignition delay time (td) is the period of time during which the voltage remains at the value of the ignition voltage while the current stays at zero.When the spark ignites,the voltage drops.The mean voltage value from ignition topower-off is the discharge voltage (Ue).The current rises sharply following ignition.The mean value of the current from ignition phase to power-off phase is the discharge current (Ie).