Papers by Author: Jiang Wen Liu

Abstract: The first component of the Polyurethane adhesive was prepared with polyester polyol, polyether polyol ,castor oil and isophorone diisocyanate. And this component was mixed with the castor oil and its modified production to prepare a two-component solvent-free aliphatic polyurethane laminating adhesive. In this study, the influences of the copolymerization ratio of polyester/ether on viscosity, heat resistance, adhesion strength and boiling resistance were studied, as well as influences of castor oil and its modified production on curing speed and adhesion strength. The results showed that when proportion of polyether diol was 25% and castor oil was 50% of the total hydroxyl content of first component, the PU adhesive with lower viscosity, better reactivity and enhanced boiling resistance would be achieved. And with an appropriate amount of derivatives castor oil in second component, the curing speed and adhesion strength of the PU adhesive were significantly improved.

Abstract: A new concavo-convex electrode has been designed and employed and it was reported that electrical discharge machining (EDM) of particulate reinforced metal matrix composites with this kind of new electrode can accelerate the debris discharge during machining so that it has a higher material removal rate (MRR) compared to the case where a normal electrode was employed. Since there are many factors that can affect the MRR in the EDM process with the concavo-convex electrode, in order to determine which is the most important factor and to optimize the machining parameters, the relative importance of the various cutting parameters on material removal rate was established using an orthogonal experimental analysis in this study. The results of the analysis suggest that to achieve a high MRR for particulate reinforced aluminum 6061 with 10-vol% Al2O3 (10ALO) or 20vol% Al2O3 (20ALO) using a concavo-convex electrode, the duty cycle is the most influential factor among current, pulse duration and duty cycle.

Abstract: A new concavo-convex electrode has been designed and employed. And an analysis of the electrical discharge machining (EDM) mechanism of a particulate reinforced metal matrix composite with this new electrode was conducted in this study. It was found that EDM with this new electrode can accelerate the debris discharge during machining so that it has a higher MRR compared to the case where a normal electrode was employed. Moreover, by studying the surface craters, it could confirm that discharge craters tend to connect together for the normal electrode. This indicates an abnormal arcing condition. Thus, the wire electrode was easy to be broken. While for the new electrode, separated craters were observed on the machined surface. This means a stable processing condition. The experiment results reveal the processing mechanism of EDM electrical discharge machining of MMCs by employing this new electrode.

Abstract: A new concavo-convex electrode has been designed and fabricated. And an analysis of the electrical discharge machining (EDM) of a particulate reinforced metal matrix composite this new electrode was conducted in this study. The material removal rate (MRR) of new electrode and normal electrode are compared in different applied voltage and duty cycle conditions. It was found that EDM with this new electrode can accelerate the debris discharge during machining so that it has a higher MRR compared to the case where a normal electrode was employed. Moreover, by studying the waveforms, it could confirm that a stable processing condition can be obtained by employing the new electrode. The experiment results reveal that it is a feasible and effective way to machine MMCs by employing this new electrode.

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.

Abstract: In wire electro-discharge machining with high traveling speed(WEDM-HS), the emulsion is used as working liquid. Because there exists a functional electrolyte, this affects the surface quality of workpiece machined. An investigation has been made into the machining feasibility when the gas or air is employed as processing medium. The first cut on workpiece is done with emulsion, and then air or distilled water is used for the second cut and multi-cuts. After machining, the surface quality and mechanical performance of the specimen under different conditions are compared. The experimental results show that air and distilled water have little influence on the surface roughness, but they can improve the mechanical performance such as the increase of hardness and the decrease of surface cracks. An orthogonal design is adopted to optimize the electric parameters and cutting passes so as to obtain the best integrative result. The experiment with air as medium reveals that it is a feasible and effective way for eliminating the electrolytic layer and improving the surface integrity of workpiece.