Papers by Author: Tie Fu

Abstract: In the meso-scale machining, feed rate, grain size and tool edge radius are in the same order of magnitude, and cutting process is often carried out in the grain interior and grain boundary. In this paper the meso-cutting process of hot-rolled AISI1045 steel is studied and its metallographic microstructure is analyzed for the establishment of multiphase models which incorporate the effect of ferrite and pearlite grains. In order to discover the applicability of multiphase models to the simulation of meso-cutting, three contrast simulation models including multiphase model with rounded-edge cutting insert (model I), multiphase model with sharp edge cutting insert (model II) and equivalent homogeneous material model with rounded-edge cutting insert (model III) are built up for the meso-orthogonal cutting processes of hot-rolled AISI1045. By comparison with the experiments in terms of chip morphology, cutting force and specific cutting force, the most suitable model is identified. Then the stress distiribution is analyzed. And it is found that multiphase model with tool edge radius can give a more accurate prediction of the global variables and reveal more about these important local variables distribution.

Abstract: A new 3-DOF parallel mechanism is presented and its kinematics analysis model was established based on the vector method. Based on the speed equations of the mechanism, its singular conditions and singular configurations were analyzed systematically. Moreover, a given mechanism’s singularity was simulated by using cylindrical coordinate search method based on its inverse displacement solutions. The results show that the workspace of mechanism with outset chains is much bigger than mechanism with inset chains. The analysis and simulation on singularity provide a theoretical basis for the dimension synthesis and optimization of this kind of parallel mechanism.

Abstract: Based on the parallel stable platform of 6-UPS, Jacobi matrix condition number and driving force of six rods are respectively identified as kinematics evaluation index and dynamics evaluation index of the parallel stable platform. By using physical programming preference functions the comprehensive preference function are constructed. Thus, a multi-objective optimization problem is formulated as a single objective optimization problem. Structural parameters with best working performance are computed by the genetic algorithm. Simulation results in Matlab show that the performance of optimization platform has been improved.

Abstract: In this paper, the development and mechanical, physical properties on cermet cutting tool material are described. By using the cermet insert NT7 developed in recent years and WC based carbide insert YT14, the tool wear, impact and cutting force tests to high strength steel 38CrNi3MoVA (hardened and tempered, HRC36~40) are processed respectively. The results of these tests demonstrate that NT7 cutting tools have better performance on some characteristics, such as wear resistance, tool life and cutting force. And its ability of impact resistance is similar to YT14. These researches will benefit to the poplarizaion and application of cermet cutting tool.

Abstract: Carbide tools play key roles in present machine manufacture. The mechanical property and cutting performance of carbide tools are improved obviously when adding micro rare earth (RE) elements into carbide tools. By means of some apparatus, such as materials testing machine, Scanning Electron Microscope (SEM), dynamometer, microscope and electron probe microanalyser, the traditional and RE carbide tools, P30 (YT5 and YT5R), P20 (YT14 and YT14R), M10 (YW1 and YW1R), K30 (YG8 and YG8R), are studied and compared by doing a lot of experiments. These experiments show that the bending strength, fracture toughness and anti-impact capability of RE carbide tools are improved remarkably, and their hardness increased a little. Moreover, the cutting force, tool-chip friction coefficient and wear of RE carbide tools decreased in cutting. In addition, the effect and cutting principium of RE element to carbide tools are analyzed and discussed, which is beneficial to the research and application of RE carbide tools.

Abstract: Diamond film made by adopting the Chemical Vapor Deposition (CVD) technology is a promising superhard material. The mechanical and physical properties of CVD diamond is between natural diamond and hot press polycrystalline diamond. The cutting tools made by CVD diamond can machine many kinds of material, such as nonferrous metals, non metallic materials and composites. CVD diamond is classified as thin and thick films, and the thick film cutting tools are widely used. However, the superhard cutting tools cannot be applied to the cutting of iron family metal and molybdenum (Mo). In this paper, data and curves on machining test of CVD diamond cutting tools are listed and then analyzed.