Papers by Author: Zhong Ning Guo

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Authors: Yuan Bo Li, Yong Jun Zhang, Zhong Ning Guo
Abstract: A micro Electrochemical Machining (ECM) system has been developed, and macro/micro complex feed mechanism has been presented in order to achieve high-resolution. A nanosecond pulse power supply for micro-ECM has been developed, and the minimum pulse width can reach 50 ns. Complementary chopper circuit has been designed to avoid waveform distortion, which can achieve higher pulse frequency. A series of ECM experiments using the machining system have been carried out, and results of tests have proved that high-resolution spindle, and high frequency, short pulse width power supply help to achieve better quality surface, higher machining accuracy.
Authors: Wei Liu, Zhi Gang Huang, Zhong Ning Guo
Abstract: The linear quadratic Gaussian Optimal control of a two-stage HFAC inverter system has been investigated in this paper. The uncertainty model of the high frequency resonant inverter is developed and analyzed with the input line and load variations taken into design considerations. The proposed control scheme has the advantages of fast response for both input line and load perturbations. It also ensures a wide range of system stability and guarantees robustness of the power converter. Both simulations and experimental results are provided to verify with the theoretical analysis through an experimental prototype with an output power of 500-W operating at 10 KHz and an output voltage of 24 V (peak value).
Authors: Bing Hua Mo, Xian Feng Zhang, Jia Qing Wu, Zhong Ning Guo
Abstract: This paper develops a model to simulate wire-to-sheet lapped resistance microwelding (RMW) process. The model employs a coupled thermal–electrical–mechanical analysis and accounts for temperature-dependent thermophysical properties of materials, contact resistance and the Peltier effect. Results show the interface temperature between the molybdenum electrode and copper wire is higher than the faying surface. The predicted thermal distributes agree well with the experimental data. The proposed model can be applied to predict the effects of the welding parameters.
Authors: Yong Jun Zhang, Yong Jun Tang, Zhong Ning Guo, Xiao Kang Liu, Feng Li
Abstract: In order to improve machining accuracy and surface quality effectively in ECM (electrochemical machining), a novel pulse inversion power supply has been presented, which has following merits such as high-frequency short pulse, high-power, and compact size. The scheme of full bridge inversion has been selected in this power supply model, and feedback circuit realizes voltage adjusted automatically, and guarantees to stability of voltage. Protect circuit has designed to avoid the problem of workpiece-burn. Finally, a series of electrochemical mechanical polishing tests using the power supply have been carried out, and the results have proved that it helps to achieve well surface quality processed, and improve machining accuracy, and also verify feasibility of its scheme.
Authors: Yu Deng, Zhong Ning Guo, Zhi Gang Huang
Abstract: In this paper, the Lattice Boltzmann Method is applied to set up the numerical model of cavitations. In order to simplify the model without losing the accuracy of simulation, the movement of the bubble wall is considered as the boundary condition for the gas and as initial condition for the fluid so the two phases (gas-fluid) physical phenomenon is divided into two simple models which are connected by the bubble wall. In the simulation, through the analysis of the velocity and the pressure distribution, it is found out that the symmetric bubble is characteristic with pulsation and high speed shock that are limited in a small field with radius of 7mm during the bubble growth. And it noted that the bubble is circularly collapsed for the symmetric velocity distribution.
Authors: Yong Jun Tang, Zhen Long Wang, Zhong Ning Guo, Yong Jun Zhang
Abstract: In order to operate in narrow space, a novel miniaturized EDM (Electro Discharge Machining) mechanism has been developed. A prototype of miniaturized EDM device based on ultrasonic motor (UM) has been developed, which has its advantage of compact size (70×40×50 mm). The differential driving electrode has been presented, and coaxial forced vibration of electrode is benefit for the evacuation of debris, so it helps to achieve stable and efficient machining. Driving principle of ultrasonic motor is analyzed, and simulation using Finite Element Method (FEM) is accomplished. The auto-frequency tracking has been carried out, in order that the motor work on resonant or quasi-resonant frequency. Finally, EDM experiment has been finished, and holes with figures of circleΦ85μm and Y-typed have been machined.
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