Yong Feng Guo

Electrical Discharge Machining (EDM) Phenomena of Insulating ZrO2 Ceramics with Assisting Electrode

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.

Experimental Research on Machining Performance of Electrode Materials in Dry EDM

Electrode materials are important factors affecting machining performances (MP) of electrical discharge machining (EDM). Experiments using different electrode materials were carried out in compressed air aim to realize MP of electrical discharge machining in gas (dry EDM). Experimental results show that a minimum pulse interval exists for given parameters and tool material. Calorific performances of tool materials are main influencing factors of MP on the condition of thorough deionization. Copper achieves the best MP in the experimental tool materials. Experimental results of different workpiece materials depict that material remove rate (MRR) and surface roughness (SR) value increase with increases of discharge energy. SKD61 steel achieves the highest MRR and SR value in the experimental materials. Material holding better performance of heat resistant, such as titanium alloy (TC4), achieves the lowest MRR.

Research on Micro EDM Machine Tool for Machining Micro Array Holes

As demands for the micro array holes in modern industry and the characteristics of micro Electrical Discharge Machining (micro EDM), a new type micro EDM machine tool used to machine micro array holes was designed and manufactured. The machine tool contains following systems: the mechanism system, the control system, the pulse generator system and other auxiliary systems. Each system was studied respectively. Base on a large number of experiments, finally, a sample with 256 array holes was processed by the machine tool. The diameter of single hole is 45µm and precision of the holes is ±1µm. The sample has been successfully applied to R & D test of micro nozzle components

Research of Temperature Field Simulation on Electrode Wire Wear for WEDM

The wire electrical discharge machining (WEDM) technology is widely used in the field of mold industry, aerospace, automobile and so on. However, in the discharge machining, the electrode wire wear will affect the machining accuracy and machining efficiency. There are many factors that affect the electrode wire wear, and cutting many work-piece and precise surveying are needed in the wear experiment, so the whole experiment is complex. This article analyzed the wear mechanism and found the main reason of affect the electrode wire wear by using the ANSYS software to do the temperature field simulation. The simulation parameters and simulation results were verified through experiments. The experiment showed that appropriate ratio of peak current and pulse width and the slow current rise slope can reduce the electrode wire wear significantly.

Investigation of the Effects of Dielectric Inlet Pressure in Inner Jetted Dielectric EDM Milling

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.

Research of Drives of Power Amplifiers of Magnetic Levitation Servo Spindle Applied to Micro EDM Based on FPGA

The drives of power amplifiers of magnetic levitation servo spindle applied to micro EDM (Electron discharge machining) based on FPGA (Field programmable gate array) are developed. The drive module that produces the PWM (Pulse width modulation) waves that conform to the requirements of spindle power amplifiers involving three-level half bridge switch power amplifier, three-level full bridge switch power amplifier and motor power amplifier, according to input of action values from magnetic levitation servo spindle controller DSP (Digital signal processor) is designed. Multi-PWM producing algorithm by single timer with multi comparing nodes is proposed. After being applied to control system of magnetic levitation servo spindle, the drives accomplish conversion from DSP action values to PWM waves. The PWMs that drive radial coil current power amplifier have phase difference of 180°. The PWMs that drive axial coil current power amplifier have dead zone time and their wave shapes are complementary. The PWMs that drive the motor power amplifier conform to requirements of power amplifier chip LMD18200. Using FPGA to realize the drive function of spindle power amplifier makes the drive design more flexible, resource distribution of DSP more optimized, the task of algorithms running more centralized, and the drives module gets simpler and more reliable because the phase shift circuit and dead zone circuit are cancelled but the function of phase shift and dead zone is reserved.

Research on Elastic Damping Control Strategy at High Speed for a Vehicle Electronic Power Steering System Stability

Electronic power steering (EPS) system is a critical component for vehicle safety driving. The damping force of automobile steering is decreased at high speeds, so the driving feel is floating. When vehicle suspension shock and a front wheel sensitive to road counterforce it is relation with the driver safety. For the subject of vehicle stability at high speed, an EPS system control strategy of stability has been presented. In order to keep driving feel, when the steering resistance decrease an elastic damping will be increased. Current follow control technique is introduced, and the torque sensor can estimate the vehicle state. This method can be verified by the experiment.

Simulation on Material Removal during Reciprocating Traveling WEDM of Insulating Ceramics

With the double layer structure model, the material removal of insulating ceramics ZrO2 during the machining process by reciprocating traveling wire electrical discharge machining (WEDM) was simulated and analyzed. The influence of conductive layer (C and ZrC) to material removal volume and crater dimension was compared. And the effect of peak current, pulse duration and the movement speed of wire electrode on discharge craters were researched. The simulation shows that the conductive layer exist has much influence to the material removal volume and crater length and width, but has less influence to crater depth during electrical discharge. The simulation for the effect of discharge parameter tells that, with the boiling removal form hypothesis, the material removal volume during single discharge is increasing with the increment of peak current and pulse duration but decreasing with the raising of wire electrode movement speed. For the variation of peak current, the removal volume of ZrO2 is exceeding the removal volume of conductive layer when Ip is bigger than 24A. Meanwhile, for the variation of movement speed of wire electrode, the removal volume of conductive layer is more than that of ZrO2 when v is over 5m/s.

Study on Modeling and Simulation of Wire Vibration in WEDM

The wire electrical discharge machining (WEDM) has been widely used in the field of metal cutting, mold industry, aerospace and so on. However, in the discharge machining, it is very important to restrain the wire-tool vibration for the improvement of machining accuracy. In this paper, it is created a model of the wire vibration with double-ended fixed, established the differential equation of vibration, and derived its full theoretical solution to analysis the vibration factors. Simulations of the wire vibration with ANSYS Transient dynamics analysis were given. An orthogonal design of the wire vibration using L9 orthogonal table was made, and the experiment found that minimize the servo voltage, reduce the pulse width, and select the appropriate wire tension and pulse interval, which can reduce the wire vibration.

A Novel Power Supply for High Speed Drilling Electrical Discharge Machining Base on Pulsed Width Modulated

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.