Papers by Author: Ming Zhou

Abstract: This paper performed a series of finite element method (FEM) simulation to investigate the influence of the tool wear on the cutting temperature in the diamond ultra-precision cutting of the aluminum alloy mirror. The two-dimensional FEM model including the diamond tool with the different average width of wear land on flank face was established. A series of ultra-precision cutting experiments using different cutting distance was performed. The tool wear was detected by scanning electron microscopy (SEM), and the cutting temperature was detected by infrared thermal imager. The comparison of the simulation investigations and the experimental investigations was done. The results revealed that the cutting temperature increases with an increase of the average width of wear land on flank face in the FEM simulation. And in the ultra-precision cutting experiments the diamond tool wear becomes severe as the cutting distance increases, meanwhile the severe tool wear results in the higher cutting temperature. Consequently the FEM simulations prove to be right.

Abstract: In this paper, ultra-precision cutting experiments were carried out with titanium alloy material Ti-6A1-4V by using single crystalline diamond tools. Experimental results show that the wear patterns of rake face of diamond tools are crater wear and groove wear, the wear patterns of flank face of diamond tools are uniform wear and groove wear, and the wear mechanisms of single crystalline diamond tool are chemical wear and mechanical wear. Graphitization and microcosmic cleavage of the diamond tools occur in the cutting process.

Abstract: Ultra-precision diamond cutting of ferrous metals has not been successful in application due to significant tool wear. In this work, numerical simulations and experimental investigations are presented in order to study the interface diffusion between diamond tool and workpiece materials. A diffusion model with respect to carbon atoms from diamond tool penetrating into chips and machined surface was established. The numerical simulation results of the diffusion process reveal that the distribution laws of carbon atoms concentration have a close relationship with diffusion distance, diffusion time and the original carbon concentration of the work material. In addition, diamond face cutting tests of die steels with different carbon content are conducted at different depth of cuts and feed rates to verify the previous simulation results. The wear morphology of rake face and flank face of diamond tool were detected by scanning electron microscopy. Energy dispersive X-ray analysis was proposed to investigate the change in chemical composition of the chips and machined surface. The results of this work benefit for a better understanding on the diffusion wear mechanism in single crystal diamond cutting of ferrous metals.

Abstract: A new non-contact liquid bearing, which utilizing traveling waves, is developed in this paper. The developed bearing is designed in an octagon shape where series of piezoelectric actuators are placed between a rigid support plate and the elastic thin bearing surface around the circumference and in the radial direction. The driving apparatus for the developed bearing is implemented based on DSP and voltage amplifiers. The liquid film force induced by traveling waves is confirmed by experiments which prove the feasibility of the developed bearing.

Abstract: In this work, cutting experiments were carried out on titanium alloy Ti6Al4V by using polycrystalline diamond (PCD) tools to investigate the effects of the tool geometries and cutting parameters on machined surface roughness. Experimental results show machined surface roughness decreases with increases in the flank angle, tool nose radius and cutting speed within a limited range respectively, and begins to increase as the factors reaches to certain values respectively. And machined surface roughness decreases with increases in feed rate and cutting depth respectively.

Abstract: A new type of hydrostatic liquid bearing utilizing traveling waves is proposed and analyzed in this research. In principle, the moving part of the proposed bearing is supported by a liquid film generated by the traveling wave transportation, which creates a liquid flow between the bearing and guide surfaces. A numerical simulation model for the unsteady and incompressible flow due to the traveling wave motion of the bearing surface is developed based on Navier-Stokes equations. The equations are solved discretely by dynamically meshing the isotropic 2D model and updating the boundary conditions. It reveals that the floating force varies with a nonzero average value. In order to suppress the undesirable fluctuation, voltage-offsetting technique has been proposed. Simulation results show that the steady floating force can be obtained. The proposed bearing design is ought to eliminate drawbacks of conventional hydrostatic bearings such as supply of external pressure source, use of compressor, and tubes while still achieving comparable static and dynamic capabilities.

Abstract: The silicon carbide reinforced aluminum matrix composites (SiCp/Al) are widely used for its high specific stiffness and high specific strength. However, the poor surface quality and machined surface defects limit its further application. The aim of this paper is to investigate the effect of cutting parameters on the machined surface defects in high-speed milling of SiCp/Al composites. The tests were performed on a high precision computerized numerical control (CNC) precision milling machine using a polycrystalline diamond (PCD) tool, and the machined surfaces were measured by the scanning electron microscope (SEM).It was found that cutting parameters have a great influence on the depth of big pits. A high feed rate and a low cutting speed correspond with a big cutting force, and result in a large depth of big pits.

Abstract: This paper performed a series of experimental investigations for typical die steels with ultrasonic vibration assisted turning. The micro-morphology of rake face and flank face of diamond was detected by scanning electron microscopy, and the roughness of machined surface was measured by Form Talysurf. In order to clarify the influence laws of cutting parameters and tool geometric parameters on tool wear and surface quality. The results revealed that the wear of diamond and surface roughness rely heavily on the feed rate, and have less relativity with the relief angle and the depth of cut to an extent. In addition, the function mechanism of ultrasonic vibration turning had been analyzed, it exhibited that this technological measure has enhanced tool life and improved surface quality to a large extent.

Abstract: The performances of particle reinforced aluminum matrix composite is excellent, but it is hard to be manufactured, which resist its wide spread engineering application. Rotary ultrasonic machining (RUM) is very suit for machining of particle reinforced aluminum matrix composite with moderate or high volume fraction. An aluminum matrix composite reinforced with 45% volume fraction of 3μm silicon carbide particles in a A12 aluminium matrix is experimental studied by RUM, and surface topography, surface roughness and cutting force are analyzed. The experimental results show that machining surface quality is high, surface roughness Ra ranges from 0.131~0.340μm, the cutting process is very smooth and cutting force Fz ranges from 23.33~51.31N, grinding wheel jams and grinding burn do not appear on rotary ultrasonic cutting tool after machining, and tool wear is extremely little.

Abstract: Based on the Kinematic analysis, the indentation fracture mechanics is used to build a force model of ultrasonic vibration mill-grinding. To verify the force model, experiments are carried out for silicon nitride ceramics with various machining parameters, meanwhile grinding forces are measured. Finally, comparison between predicted results with experimental results is presented.