Papers by Author: Yun Ming Zhu

Abstract: In this paper, the forming processes, main effect factors and change law of the cutting direction burr in orthogonal cutting have been studied and related theories are analyzed based on the cutting experiments. The result shows that the forming processes of cutting direction burr consist of normal cutting, flexure deformation of end surface of workpiece, plastic effect, continuous cutting and shear-break separating in orthogonal cutting. And a new phenomenon was found that cutting direction burr is formed with the shear-break separation of the chip and workpiece machined surfaces. In addition, the size of cutting-direction burr varies with workpiece materials, cutting parameters and geometric parameters of cutting tool. The study may be important science and practical value in order to control and reduce cutting burr in precision machining.

Abstract: A finite element model was developed for simulation of feed direction burr formation process in turning. Based on a series of stress and strain contours the progressive change of geometry at the edge of workpiece edge from simulation, a turning feed direction burr formation mechanism is proposed and divided into four stages: normal cutting stage, deformation of workpiece edge stage, continues cutting stage and final developed stage. The removal of the remaining part of allowance takes place close to the tool tip as the material has sufficient rigidity to allow cutting only in this area in final developed stage and secondary burr will be formed; primary burr will be formed in final developed stage if the remaining material has no rigidity to allow cutting continually in final developed stage. The burr size and burr shapes form simulation results are consistent with the experimental results. Finite element model generated here provided a numerical analysis method to solve the prediction of burr formation and physical insight into the fundamental burr formation mechanism.

Abstract: Micro-milling is widely used in material removal processes in industry. However, burrs are often formed on workpiece edges in milling process. Burr effects the dimensional tolerance and performance of the workpiece seriously and is desirable to be controlled. Burrs prediction technology is useful for cutting conditions optimization to control burrs forming. Due to lots of factors influencing the formation process of burr, it is a difficult task to establish the burr size prediction model by mathematical and mechanical method. RBF neural network was used for burr formation predition. Design of the network, network structure parameters determination and generalization capability of the network were analyzed and discussed. Achieved network has good fitting performance and generalization capability validated by experiments.

Abstract: Burrs and fractures are two types of shapes formed on exit edges in pricision machining. They affect the quality of workpiece and the efficiency of prodcution seriously. A finite element model of fracture formation process to simulate the machining process of 2024-T3 Aluminum alloy is proposed. According to simulation results, five stages and variation of shear shain in fracture formation process are analyzed. It is found that shear strain plays an important role in fracture forming process. The method of determination of critical shear strain for fracture forming is proposed from simulation results.

Abstract: The end surface angle of workpece is one of key factors that affect burr sizes and shapes. In this paper, the burr formation process of different end surface angle is simulated with elastic plastic nonlinear element method based on ABAQUS. The influence of end surface angle of workpiece on burr formation processes in high-speed machining 2024 Aluminum alloy is analyzed. The influence of end surface angle on burr sizes and shapes is studied based on equivalent shear strain and negative shear angle. The results have investigated the mechanisms of burr formation fundamentally, which is the basis of burr minimization.

Abstract: The metal cutting burr is one of the factors that influence the edge quality and performance of precision parts.A finite element model has been established to investigate the mechanism of burr formation and limit transformation in high-speed machining 2024Aluminum alloy .The burr/fracture formation process is simulated with elastic-plastic nonlinear element method based on ABAQUS.This paper has investigated the mechanism of burr /fracture formation and the limit transformation condition of cutting-direction burrs and fractures in high-speed machining and the limit transformation condition change with the cutting condition,which lay scientific basis of further research on cutting burrs formation and its minimization and deburring technology.

Abstract: In most machining operations undersirable burr or negative burr is created at workpiece edges. The burr/negative burr formation mechanism is analyzed based on shear strain which is obtained from simulation results of the finite element model of burr/negative burr forming process. To varify the simulation results, experiments are conducted. We observered that there exists a critical value of shear strain for burr/negative burr transformation. Burr or negative burr, which to be formed at workpiece edges can be controlled by adjusting the cutting conditions or tool geometric parameters. Edge quality of workpiece can be controlled by converting burr or negative burr forming.

Abstract: The two-side burr is one of the important factors that influence the edge quality and performance of precision parts. The two side-direction burr formation process is simulated with DeformTH3D. The mechanism of two-side burr formation is analyzed in terms of the results of the simulation. Enlarging the tool orthogonal rake and minimizing the depth of cut can reduce the burr size.

Abstract: A forming model of the feed-direction burr for drilling process is made in this paper. The feed-direction burr formation is studied by experiment. The related theories are analyzed. The influence factors of the feed-direction burrs are pointed out. Furthermore, a certain number of measures to prevent and decrease the burr in drilling process are advanced.

Abstract: Based on grind-hardening experiments, the two side-direction burrs were studied. Three main stages (burr generation, augmentation and formation) in the burr yielding process were clarified and the varying laws of burr morphologies and dimensions were systematically revealed. In turn raises, some new technologies, processes and methods of actively controlling burrs were put forward.