Papers by Author: Yong Feng Guo

Abstract: Micro-EDM technology has the advantages of no-contact and no-cutting force, it has been used in many fields. In order to use micro-EDM to machine proprietary micro array holes, which needs high precise of hole spacing and consistent hole diameter, a new macro-micro dual-drive system of micro-EDM have been made. It uses macro drive to move to a place, measures the error with the high precise grating, and uses micro drive to compensate the error. Online measurement proved that this method has important value if it will be used in micro-EDM.

Abstract: In layer-by-layer EDM milling based on inner jetted dielectric, the dielectric inlet pressure is an important process parameter and has great influence on the machining characteristics. So, numerical simulation of the liquid-solid two-phase flow field in discharge gap is conducted. The simulation results of debris concentration reveal that the debris can be evacuated from the discharge gap in time, which increases the machining process stabilization and improves the machining efficiency. Finally, the effect of dielectric inlet pressure on material removal rate (MRR) and tool wear ratio (TWR) were also researched and discussed. The optimum inlet pressure, which maximized the MRR and minimized the TWR, was found through experiment.

Abstract: In Wire Electro Discharge Machine (WEDM), as the big randomicity of electro discharge, single discharge energy is various. In this paper a resistor-less and half-bridge power supply is investigated based on pulse width modulation(PWM), whose single discharge energy is equal , adopting discharge control strategy of breakdown waiting. And the experiment shows the cutting speed and surface roughness of this isopluse power supply is superior to that of traditional isofrequency power supply.

Abstract: In this paper, a novel Pulsed-Width-Modulated (PWM) half-bridge High Speed Drilling Electrical Discharge Machining (HSDEDM) power supply has been developed. This power supply has excellent features that include minimal component count and inherent protection. This topology has an energy conservation feature and eliminates the output bulk capacitors and current limiting resistances. Energy used in the erosion process will be controlled by the switched Insulated Gate Bipolar Transistors (IGBTs) in the half-bridge network and be transferred to the gap between the tool and work-piece. The relative tool wear and machining speed of our proposed topology have been compared with that of a normal power supply with current limiting resistances.

Abstract: Super-capacitors are new equipments for energy storage，and they have wide application in practice. At present, blanking is used to machining the electrodes of super-capacitor; however, the disadvantages of the method are burrs, electrode collapse. A new method processing electrode of super-capacitor, wire electrical discharge machining in gas (dry WEDM), were presented in this paper, and the electrode surface morphologies were studied utilizing scan electron microscope (SEM). First, the surface morphologies comparison studies of super-capacitor electrodes processed with different method, such as shearing, blanking and dry WEDM etc., were performed, and research results show that the super-capacitor electrode surfaces machined by dry WEDM achieve flat machining surface, and electrode edges do not collapse. Further surface morphology analysis was carried out based on different pulse durations and air pressure, and analysis results indicate that better machining surface can be achieved when suitable pulse duration and gas pressure are selected. Finally, surface energy spectrum analysis of the super-capacitor electrode processed by dry WEDM is performed, and the analysis result show that alumina are formed on the middle of electrode, aluminum foil, which is favored to the performance of super-capacitor.

Abstract: Advanced engineering ceramics are more and more widely employed in modern industries because of their excellent mechanical properties such as high hardness, high compressive strength, high chemical and abrasive resistance. These properties limited the machining to the insulated ceramics. This paper investigates the electrical discharge machining (EDM) of ZrO2-based ceramics by assisting electrode method. The theory of assisting electrode method is introduced. The machining phenomena under different electrical parameters were studied. The material removal mechanisms change with the increase in the power of single pulse. Some work-pieces have been machined successful through the assisting electrode method.

Abstract: Advanced engineering ceramics are more and more widely employed in modern industries because of their excellent mechanical properties such as high hardness, high compressive strength, high chemical and abrasive resistance. This paper investigates the high speed wire electrical discharge machining (HS-WEDM) of Si3N4-based ceramics by assisting electrode method. The theory of assisting electrode method is introduced. The machining phenomena under different electrical parameters were studied and the optimized machine pulse width was got. The material removal mechanisms change with the increase in the power of single pulse.

Abstract: This paper deals with nanometer positioning in the presence of friction. The object studied is a ball-screw-driven and linear-ball-guide-supported table system. For this system, the friction dominates the resulting performance for micro-motion and the system exhibits microdynamic characteristic which is rather different from macrodynamics. Inherently a controller with high loop-gain is needed to suppress the effect of friction. A PID controller is designed for the table system for step height smaller than 10μm. Experiment and simulation results indicate that the PID controller can provide a sufficiently high-loop gain and effect of friction is suppressed. In point-to-point(PTP) positioning for step heights from 10μm down to 10nm, the positioning error is within ±2 nm and the response dynamics is satisfactory.

Abstract: This paper deals with nanometer positioning in the presence of friction. The object researched is a ball-screw-driven and linear-ball-guide-supported table system. For such system, models that do not account for friction can only be applicable to describe the macrodynamic behavior which is significantly different from the microdynamic one. A PID controller is designed with high-loop gain to suppress the effect of friction. The controller parameters are calculated by pole placement according to macrodynamics, no identification of friction and friction model are necessary. Experiment and simulation results indicate that nanometer positioning can be realized in this system by the controller. In point-to-point (PTP) positioning for step heights from 0.1μm to 1mm, the positioning error is within ±5 nm and the response characteristics are satisfactory.