Papers by Author: Hai Jun Qu

Abstract: Cutting-direction burr/fracture is one of the important factors that influence the edge quality and performance of precision parts. The formation of negative shear zone decisions the edge quality of workpiece. A finite element model has been established to investigate the mechanism of negative formation in machining H64 brass. The negative shear zone formation process is simulated with rigid-plastic nonlinear finite element method. The cutting direction burr forms when the stress of principal shear zone great than it in negative, the cutting direction fracture forms when the stress of principal shear zone less than it in negative and there is a crack in the area near the tool tip and grow along the negative shear zone .

Abstract: Cutting direction burr/fracture is one of the important factors that influence the edge quality and performance of precision parts. A finite element model based on material failure mode is developed in this study to simulate the burr /fracture forming process. According to workpiece materials deformation and mechanical properties from the simulation results, the cutting direction burr/fracture formation process is analyzed. The cutting direction burr forms when there is a crack in the area near the tool tip and grow along the principal shear zone, the cutting direction fracture forms as the crack grow along negative zone.

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 two side direction burr formation process. Based on strain distribution, a two side burr formation mechanism was proposed. Burr form and burr size of simulation are close to that's of experiment. Finite element model generated here provided a numerical analysis method to solve the prediction of burr and chip formation and physical insight into the fundamental burr formation mechanism. The stain in two side direction of material near the side face decides the shape and the size of two side direction. Multi-workpieces are machined at the same time with side face closely by each others can control the formation of two side direction strain and two side direction burr.

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: 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.