Advanced Materials Research Vols. 690-693

Abstract: 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.

Abstract: In order to get an accurate analysis results for static and modal characteristics of a machining center, finite element analysis method was taken. Taking a horizontal machining center as example, solid model was established firstly. Finite element model containing joint parameters was established in ANSYS. With the help of finite element method, static and modal characteristics of the horizontal machining center were carried out. It was concluded that the horizontal machining center has comparatively smaller static stiffness in Z direction; in order to improve modal characteristic of the horizontal machining center, the column and worktable should be paid more attention. The research results provide guidance for finite element analysis and optimization of whole machine tool.

Abstract: The relationship between machinability and microstructure of plastic mould steel is still not clear enough, despite the application of plastic mould steel is more and more wide. In this study, two typical plastic mould steels, namely, 718 (DIN 1.2738) and SDP1 steel with the same hardness are chosen to investigate turning force, tool wear and milling force by experimental test. Combining with the turning and milling test, discussions about cutting force and the relationship between machinability and microstructure are made. And it’s found that the micro-uniformity has a great effect on the machinability of plastic mould steel.

Abstract: On the basis of the establishment of the three-dimensional solid model of the roll grinder grinding head spindle system, carry out finite element static analysis, with the spindle structural stress and strain diagram, study its static characteristics, carry out modal analysis in the properly simplified spindle system with the finite element method, analyze the calculated natural frequency value , study dynamic characteristics of the spindle system, realized the dynamic design of the product.

Abstract: Through the research on the change of system input and output energy in time-varying speed cutting, the influence of variable-speed waveforms on vibration suppression effect in time-varying speed cutting is quantitatively analyzed in this paper. A conclusion can be drawn that sine wave speed variation is better than triangle wave speed variation in vibration suppression.

Abstract: Carbon fiber reinforced plastics are widely used in aerospace and aircraft industries because of their remarkable advantages such as lightweight and high strength. However, as their properties are different with metals, those materials are difficult to machine in conventional ways, the machining defects may appear and the machining accuracy and surface quality are difficult to guarantee. Oriented to drilling of carbon fiber reinforce plastics, a machining model based on finite element method are presented in this paper, the drilling simulation of carbon fiber reinforced plastics using Deform-3D are realized, and the factors which influence the machining quality of the hole are analyzed in-depth. It shows the simulation results are accord with the results from the literatures and experiments and can used as evidence in drilling parameters optimizing and drilling quality improving.

Abstract: The gears which are being used in offshore applications are to be manufactured by using materials which are having heat resistance, corrosion resistance , high strength and with standing for higher fatigue loading. This research work deals with the experimental study and analysis of various parameters of gear milling process which would effects the microstructure and surface finish of gears. Analysis have been done on various cutting parameters during the gear cutting process of Aluminium boron carbide composites. The A6061 is reinforced with Boron carbide by using the stir casting process with 10 wt. % and 15 wt. % of B₄C compositions .The experimental evaluation of effect of milling parameters on surface finish and microstructure are carried out for gear milling process by varying the feed,depth of cut and the corresponding cutting force, vibration and roughness during the machining of tooth have been measured.

Abstract: Abstract．Drilling quality in manufacturing medium density fiberboards (MDF) is greatly affected by delamination. In multi-spindle drill machine, the feed is provided by feed pressure generated by air compressor. This study focus on relation between delamination and machining parameters in drilling MDF with variable feed pressure. The relation is investigated by establishing second order polynomial models using response surface methodology, and the analysis of variance (ANOVA) is employed to verify the validity of the models. It is found that the delamination factor increases with the decrease of drill hardness and with the increase of feed pressure both at entry and exit of MDF. However, at low level hardness and high level feed pressure, the delamination factor is insensitive with variation of drill hardness and feed pressure.

Abstract: Building a forecast model of cutting surface's residual stress due to different cutting parameters and finding the optimal combination of cutting parameters is the demand of developing ultra precision industries such as aviation and aerospace. Owing to the limitation of the least square method and other conventional methods, genetic algorithm was introduced into the parameter identification of cutting surface's residual stress forecast model and to optimize cutting parameters. In this way, a cutting surface's residual stress forecast model of aluminum alloy is given. By contrast, genetic algorithm is more suitable to identify parameters of cutting surface's residual stress forecast model, and to guarantee the optimal cutting parameter combination.

Abstract: This paper presents the surface roughness model which is proposed and developed to predict the surface roughness in the CNC turning of the carbon steel with the coated carbide tool under various cutting conditions by using the response surface analysis with the Box-Behnken design based on the experimental results. The in-process monitoring of the cutting force and the cutting temperature is utilized to analyze the relation between the surface roughness and the cutting condition. The tool dynamometer and the infrared pyrometer are employed and installed on the turret of CNC turning machine to measure the in-process cutting force and cutting temperature. The models of cutting force ratio and cutting temperature are also developed based on the experimental data. The optimum cutting condition is determined referring to the minimum surface roughness of the surface plot, which is obtained from the developed surface roughness model. The experimental results show that the higher cutting speed gives the better surface roughness due to the higher cutting temperature, however the tool life becomes shorter. The feed rate is the most significant factor which affects the surface roughness, while a small depth of cut helps to improve the surface roughness. The effectiveness of the surface roughness prediction model has been proved by utilizing an analysis of variance (ANOVA) at 95% confident level. Hence, the surface roughness can be predicted and obtained easily referring to the developed surface roughness model.