Xue Feng Bi

Calculation of Material Flow in Orthogonal Cutting by Using Streamline Model

The streamline method was used to investigate the plastic strain rate in machining. The streamline function presented in this paper is a general equation with three parameters controlling the complex variation of flow line shape. Velocity and deformation field were obtained by streamline analysis. The validation of this model was conducted by comparing with other experimental results published. It shows that the streamline model presented in the paper can be applied to the evaluation of strain rate in machining.

Temperature Rise and Heat Transfer in High Speed Machining: FEM Modeling and Experimental Validation

Numerical and experimental approaches are mutually conducted to investigate the temperature rise in steel machining at high cutting speed. The process is modeled using a fully coupled thermo-mechanical finite element scheme. Cutting tests were carried out at 38 m/s on a ballistic orthogonal cutting set-up equipped with an intensified CCD camera. Analysis of experimental results leads to determine the variables which control heat transfer between the tool and chip. A discussion about the most important parameters controlling the temperature rise at the tool-chip interface is then proposed. The results also show that the temperature-dependence of the frictional stress modeling can improve the accuracy of the numerical simulations.

Research on Crater Wear Monitoring in Turning

Tool wear is a significant research field in metal cutting because it affects not only the tool cost and replacing time, but also the productivity and surface quality. Tool wear monitoring is a key technology in tool wear research. A series of turning tests with different cutting time are implemented. Cutting power in cutting process is acquired by a power senor and crater wear value after cutting is measured. Time domain analysis of power data indicates that root mean square increases and kurtosis approaches to 0 with crater wear increase in turning process.

Effects of Grinding Parameters on Creep Feed Grinding

Creep feed grinding can obtain an excellent grinding performance for its creep feed with high depth of cutting. However the large contact length and large feed result in large amount of heat accumulating in working zone and cause burn on workpiece surface. A series of grinding tests are performed to obtain burn variation with grinding parameters using different grinding wheel and workpiece in this paper. Grinding energy is also recorded and used to evaluate the influence of grinding parameter on burn.

Comparison Analysis of Plastic Deformation in Metal Cutting with Cutting Simulation and Streamline Model

Strain and strain rate are two important parameters evaluating plastic deformation of workpiece in cutting process. Finite element simulation is implemented to estimate plastic deformation of wokrpiece in this paper. Flow net function in simulation is used to capture deformation state of grids on workpiece, and the deformation result is compared with that observed by Stevenson and Oxley in cutting test. Point tracking function in simulation is utilized to calculate strain and strain rate distribution along flow lines, and the results are also compared with that calculated by streamline model.

Crater Wear Modeling in Conventional Speed Machining

Wear modeling makes it possible to predict the evolution of wear profile and explain wear mechanism from process variables, such as temperature, pressure and sliding velocity etc. A composite crater wear model considering adhesive and diffusion wear is established by means of experiment and modeling in conventional speed machining. A series of cutting tests are performed to obtain wear profiles and corresponding process variables. The constants in wear model are fitted by regression analysis with crater wear tests. This crater wear model shows a good predictive capability in conventional cutting speed.

Development of Machining Method for Micromold

Micromold manufacturing technology is very important for the mass production of micro parts. In this paper, modeling of micromold is established in 3D software firstly. The 3D modeling is input into machining simulation software Master CAM to simulate machining process. The machining parameters and cutting tool path are optimized in machining simulation. Machining G code of micromold obtained from post-process program of Master CAM is input into HMI system of Micro Machine Tool (MMT), and hence the micromold will be machined precisely in MMT.

Influence of Chip Curl on Tool-Chip Contact Length in High Speed Machining

The tool-chip contact length, as an important parameter controlling the geometry of tool crater wear and understanding chip formation mechanism, is widely investigated in machining. The aim of this paper is to study the influence of chip curl on tool-chip contact length by means of experimental observations with high cutting speed. The relationship between tool-chip contact length, chip radius of curvature and uncut chip thickness was investigated. Experimental results show the effect of increasing spiral chip radius on tool-chip contact length with low uncut chip thickness in high speed machining.

Research on the Influence of Shields to Thermal Equilibrium of CNC Machine Tool

In order to investigate that shields have the effect on the thermal equilibrium of CNC machine tool, this paper applies the theory of heat transfer and finite element analysis to analyze the thermal characteristics of CNC lathe CK40A/1000. By ANSYS software, the temperature distributions of spindle engine, headstock and bearing at thermal equilibrium with/without shields are obtained. By analyzing thermal equilibrium patterns and experiments, the temperature of spindle bearings with shields are 3-4 higher than without shields at thermal equilibrium. And shields have less influence on the temperature gradient of tool inner thermal sources.

Determination of Chip Velocity Field in Metal Cutting

Chip velocity is a crucial parameter in metal cutting. The continuous variation of chip velocity in primary shear zone can not be obtained from conventional shear plane model. Therefore a general streamline model was used to investigate the distribution of chip velocity field in metal cutting. This paper also verified the continuity of plastic flow in metal cutting by tracing the variation of particle area. The velocity of chip material was calculated from the mathematical expression of streamline model. The velocity results were compared with conventional shear plane model.