Papers by Author: Z.N. Guo

Abstract: Resistance Spot Welding (RSW) is a widely used technology. And the rapid wear is the main reason for the short life of RSW electrodes. To improve electrode life during RSW, a novel ultrasonic-aided electro-spark deposition technology (UESD) and device are proposed in this paper. The WC metallurgical bond coating was fabricated on the surface of CuCr1 electrodes by UESD, and some experimental results were also analyzed. Moreover, the surface morphology of WC coating was studied by SEM and the quality of coating wear resistance was analyzed through experimental method. This study provides a novel way to extend the life of common moulds and RSW electrodes.

Abstract: Since Particle Reinforced Metal Matrix Composites (PRMMC) normally applied Al2O3, SiC particle and other hard material as reinforce item, traditional manufacturing processes are hard to machine PRMMC with high efficiency and low tool cost. This paper presents an electrochemical mechanical (ECMM) hybrid polishing procedure for PRMMC, and the influences of parameters such as work voltage, grinding area proportion, the formula and concentration of electrolyte has been investigated. Through a hybrid polishing compound with a no Z direction feed pure mechanical grinding progress in Vx opposite direction, Ra around 0.5um PRMMC surface can be achieved.

Abstract: A nanosecond pulse power supply for micro-ECM (Electrochemical Machining) has been developed, and the minimum pulse on-time is 50 ns. After the influence of ultra-short pulse on micro-ECM was analyzed, complementary chopper circuit was presented to avoid waveform distortion, which can achieve higher pulse frequency. A fast protect circuit was designed, and its response time is less than 5μs, which can avoid damaging workpiece and electrical components by switching off machining voltage and step motor as soon as a short circuit was detected. A series of ECM experiments using the power supply have been carried out, and results of test have proved that high frequency, short pulse width power supply helps to achieve better quality surface, higher machining accuracy.

Abstract: The technology of electro-spark deposition has been investigated and the thickness of H13 steel coating up to 16.2μm has been achieved by applied SH-1000 electro-spark deposition power. It analyzed the effect of parameters such as voltage, discharge frequency, argon gas flow and rate deposition on the deposition thickness. The optimum deposition parameters have been selected through the orthogonal design. In order to improve coating quality, a novel method based on ultrasonic-assisted electro-spark deposition has been put forward.

Abstract: This paper presents a electrochemical-mechanical combined polishing progress of Cr12 hardening steel with a new kind of embedded tool. The embedded tool has been composed of two parts, the metal base acting as electrode and the inlayer with electroplating diamond grains on its outside surface which serves as mechanical grinding abrasive. The two parts are agglutinated by adhesive which can keep a good insulation of the inlayer during the mechanical process. The inter-electrode gap can be changed by altering the metal base and inlayer’s diameter. Through the investigation of numerical simulation and polishing experiment, it can be found that lower feed, reciprocate speed, longer trip of reciprocating, smaller diamond grains make better surface quality.