Papers by Author: Xian Li Liu

Abstract: This article takes common material Cr12MoV for automobile panel die as research object, aiming at difficulties when tool cutting in workpiece which are caused by high material hardness in maching, based on simulation software DEFORM-3D, a high precision simulation model of cut-in process in hard milling die steel is established, and the accuracy of the model is verified by tests, the milling force cut-in process in hard milling die steel is studied, the influence law of different cutting parameters and cut-in angles on milling force in milling cutter cutting in workpiece is analyzed, and the optimized cut-in angles are obtained, this study provides a reference for further optimization of cut-in conditions, reducing tool early damage and improving processing efficiency.

Abstract: The high temperature strength of Ni-based superalloys coupled with excellent corrosion resistance make them ideal for aerospace applications. However, the difficulty in finish machining superalloys with the carbide tools presents the short tool-life. Polycrystalline Cubic Boron Nitride (PCBN) is potential to machine superalloys. To data, there are many researches about PCBN tool wear, but only little papers showing how the surface roughness and the wear speed are influenced by cutting parameter and the coolant during the differences periods of PCBN tool wear. This investigation has been conducted to show that the PCBN tool wear is slower with cooling that without cooling during cutting superalloys with PCBN tool especially in VB up to a certain value. It is shown that tool fracture can be reduced by using the cooling. In the process of PCBN tool wear, in addition, there are some differences of the effect of the cooling for roughness Ra values.

Abstract: Milling forces simulation is a critical part in the NC processing simulation system, unstable milling forces not only affect tool life, but also can reduce the surface machining quality. Based on the existing milling forces model of ball end mill, this paper establishes a milling forces simulation system which makes seamless integration of geometric simulation and physics simulation come true on UG platform with Matlab and VC++ mixed programming technique.

Abstract: This paper mainly focus on the researches of tool wear mechanisms in turning Ni-based superalloy GH706 with PCBN insert. First, the process of flank face wear and rake face wear are studied by observing the pictures of tool wear. There are notch wear and flank wear on the flank face, and there are built-up-edge and micro-chipping on the rake face. Secondly, tool wear mechanisms are researched by combining the tribology and chemistry. A phenomenon called furrow effect cause flank face wear, and there are some chemical reactions on the rake face in cutting process. Lastly, in order to make sure a tool wear value which may be as a standard of PCBN tool in turning GH706, the relationships of cutting forces and flank face wear V_B are showed by drawing the curves of cutting force values along V_B, which indicate cutting forces turn up at the point where V_B =180μm.

Abstract: The finite element modeling and experimental validation of three-dimensional heavy cutting of high strength steel (2.25Cr-1Mo-0.25V) are presented. The commercial software Deform 3D applied for the finite element modeling is studied the effect of feed rate on the principal cutting forces and the temperature fields. The friction between the tool and the chip is assumed to follow a shear model and the local adaptive remeshing technique is used for the formation of chip. The feed rate significantly affects the cutting forces, but slightly influences the maximum temperature of the chip. The simulation results are compared with experimental data and found to be in good agreement.

Abstract: In this paper, the effect of cutting parameters on cutting force, cutting temperature and surface roughness on cutting force, cutting temperature and surface roughness are experimentally studied in spray cutting GH4169 Ni-base superalloy used carbide cutting tools. The results showed that reasonable choice of cutting parameters can effective reduction of cutting force and cutting temperature, and improve the machining surface roughness. Thus realizing clean production mode.

Abstract: For its good processing flexible, economic and environmental protection performance, hardened steel GCr15 is used widely in car and energy industry. Although surface quality in machining process is not controlled well, that restricts application of hardened steel GCr15 extensive to a certain degree. Therefore, this study revealed the effect of cutting parameters on surface roughness. Also influence of cutting conditions on surface morphology and organization generation mechanism of subsurface were stuied for high-speed cutting hardened steel GCr15. Appear reasons of plastic side flow on surface was researched. Also, effect of tool wear on surface quality was studied as well. The research results provided theoretical basis for rational choice for high speed hardened steel cutting process.

Abstract: To solve excessivly large deformation and vibration problems in machining large tube section, ensure the machining accuracy and quality of the tube section, the main tool carrier system of a large vertical lathe is designed, by simulation means of finite element, static analysis, dynamic modal analysis and dynamic response analysis are respectively carried on the main tool carrier structures designed. A reasonable overhang length of the tool in the tool carrier system is given through static analysis, dynamic modal analysis show the higher natural frequency of the tool carrier system, the production of cutting resonance can be avoided, the maximum response and corresponding stress conditions of the system under the harmonic loads are given by dynamic response analysis, analysis results show that the sustainable dynamic characteristics of tool carrier system can meet the machining requirements.

Abstract: This paper presents a design idea of PCD tool drilling CFRP and analysis of experiment of two types PCD tools machining CFRP. Firstly, parameters of PCD drill including cutting edge type, clearance angle and two point angles were improved by the mean of surveying variation of axial load values and quality of CFRP hole exit. Secondly, two types of burrs were defined from aspects of burr generated mechanism by observing plenty of burr pictures. Lastly, making use of MATLAB software, function between axial load and hole numbers were ensured by data fitting in tool life analysis.

Abstract: With the advantage of neural network in dealing with non-linear problem, this paper has established a BP artificial neural network model of non-linear mapping for tool parameters, cutting parameters and white layer depth value in precision hard turning. Results indicate that the model is of high accuracy and of extensive ability to deal with problem, and can accurately predict surface whiter layer in precision hard turning. This research will provide essential help for selection of cutting parameter and tool parameter.