Papers by Author: Z.J. Wu

Abstract: The cutting zone temperature is the basic cutting process physical parameter, how to obtain it accurately is a problem over the years. In the paper, a method combined the artificial thermocouple method with thermal conduction reverse seeking method was proposed. The thermocouple can track the temperature history curve of the tool measured point. Then the tool and cutting process heat conduction models were built up in the ANSYS and AdvantEdge FEM respectively. According to the simulation results, the corresponding relationship between the rake face temperature and the measured point temperature and the shear slip face temperature can be solved. So the first and second deformation zone average temperature was obtained. Shown as the research results, the method proposed in the paper can obtain the small cutting zone temperature effectively. It provides technical support for the study of cutting process deformation and friction behavior.

Abstract: This paper proposes a method of determining the constitutive equation parameters of a Japanese type of alloy steel (SCM440H) for Finite Element Analysis (FEA) of orthogonal cutting, involving pressure bar experiments, orthogonal metal cutting experiments and FEA inverse identification. First, Split Hopkinson Pressure Bar (SHPB) experiments combined with Quasi-Static pressure tests were conducted, and after analyzing and processing the experimental data, one set of original constitutive constants was obtained; in the mean time, orthogonal cutting experiments were also performed to collect the cutting force data. Then the original constants were put into FEA software to simulate the cutting process. But comparison between the orthogonal cutting experimental and the simulation results revealed the inadequacy for the constants to predict cutting forces. To address this problem, an inverse identification method was employed to optimize the constants iteratively. And after a certain number of iterations, the ideal parameters for FEA of the orthogonal cutting process were finally determined.

Abstract: This paper provides heat transfer modeling analysis and parameter optimization for wafer system of laser annealing equipment. Heat transfer models are established at axial and radial directions. With the help of programming calculation, the relation between heat flux of radiation and distance of adjacent layers can be analyzed. In order to minimize heat transfer interference on the motor system, optimized parameters are selected. Performance of certain selection is verified by FEA simulation and experiment data.

Abstract: KDP crystal is a good nonlinear optical and electro-optical crystal material. However, KDP crystal is considered to be one of the most difficult machining materials due to its inherent properties. This paper presents a preliminary experimental study on surface roughness of KDP crystal processed with rotary ultrasonic face milling. The study shows that the process variables (spindle speed, feedrate, and milling depth) have significant influence on the surface roughness in processing KDP crystal. It discusses the effects of the mechanical properties of KDP crystal on the processing performance. The experimental investigation reveals that the rotary ultrasonic face milling method can obtain smoother surface, which means the method is available for processing KDP crystals with a proper machining conditions. This preliminary research affords a guiding significance for precision processing KDP crystals.

Abstract: This paper provides the methodology on analyzing the dynamic characteristic of machine tool in consideration of joint parameters. To ensure the dynamic model is available for further study, modal experiment for vertical machining center is involved. The machine tool is divided into several parts and connected with spring and damping for substructure modeling. Particularly, the bolt-fixed joint is an example for the joints modeling. Based on the dynamic model, simulation of modal analysis and harmonic response are carried out. Besides, method of optimization design of column and milling box is given to improve the performance, which is proved to be feasible in harmonic response.