Papers by Author: Jie Sun

Abstract: A purely analytical method, based on the meshing theory, is presented to establish the exact helical groove and circumferential cutting edge model of end mills, for the solution of its low design precision and efficiency problems. Firstly, a coordinate system to represent the relative space position relations between grinding wheels and end mills is built and the mathematical model of the helical groove is precisely calculated with a given wheel profile and relative movements between the wheel and the workpiece. Then, the rake angle, inner radius and wheel positions of machining the clearance faces is computed. Finally, a 3D model of the end mill is generated by using OpenGL.

Abstract: Linear expansion coefficient (CTE) is one of the important thermal parameters for materials, which has a great influence on the thermal deformation analyzing. Thermal Mechanical Analysis (TMA) is adopted to measure the CTE of pre-stretched aluminum alloy sheet 7050-T7451 in three vertical directions. The mathematical functions of CTE of aluminum alloy 7050-T7451 are established, which is with three directions and reflect the influence of the temperature. A comparison between the accurate CTE data and the CTE from reference is carried out .The reason of the CTE variation of aluminum 7050-T7451 with temperature also been explained qualitatively.

Abstract: In this paper, a finite element model with respect to actual state of micro-cutting is established by adopting software of ABAQUS/Explicit. Based on the FE model, the cutting force and specific cutting force with various uncut depth of cut with different cutting edge radius are compared and then analyzed with regard to this simulation. In micro-cutting, the nonlinear scaling phenomenon is more evident with the decreasing of uncut chip thickness. The likely explanations for the size effect in small uncut chip thickness are discussed in this paper.

Abstract: The difficult-to-machine property of titanium alloy has been on important subject in the field of manufacture, especially for the thin-walled structure. The material removal amount can reach 95% and even 98%. This paper applies the finite element method (FEM) to evaluate the process of machining. The influences of the different tool paths in rough machining frame structure is studied. The influence of the tool path on the dynamic characteristic in finish machining thin-walled frame structure is also investigated. As a result, the tool path in rough machining will influence the machining efficiency and tool life and influence the dynamic characteristics of thin-walled components in finish machining.

Abstract: The mechanism of micro-milling modeling for aluminum alloy 7050-T745 is to be investigated, and a finite element model for micro-milling that reflects the actual state of the three-dimensional micro-milling is built by adopting the software of ABAQUS/Explicit. Experiment is conducted to verify the validation of the model. Simulated chip morphology in different cutting parameters agrees to the experimental results very well. Based on the FE model, cutting stresses, equivalent plastic strains, temperatures distribution and cutting forces are obtained and analyzed. This provides a good method to investigate the micro milling principles.

Abstract: This paper describes a new approach to establish the helix flute model of solid carbide end mills. Based on the theory of differential geometry and coordinate transformation, a mathematical model of the end mill helix flute will be established.The main idea of the study is to envelop the helix flute by a one-parameter surface group which consists of the cross-sectional profiles of the wheel.Then, the mathematical model will be quickly verified by MATLAB.Thus the end mill design time will be saved and the new mathematical model will be checked effectively.

Abstract: Aimed at the design of the radius of flute for solid carbide end mill, a new oblique cutting model for milling was established based on the simplified model of milling layer. Depending on this model, an equation was developed to calculate the maximum chip thickness in milling. An oblique cutting simulation via FEM(Finite Element Method) was conducted to verify the equation. The conclusion was that the result gained from the simulation was in a good agreement with the present model, so the present model is reasonable to predict the maximum chip thickness in milling and to determine the radius of the arc at the bottom of the flute.

Abstract: Cooling/lubrication conditions have significant influences on surface integrity, chip morphology, tool life and eventually productive efficiency when machining titanium alloy Ti6Al4V. Milling experiment under different cooling/lubrication conditions, namely dry, wet, MQL and nitrogen gas jet were conducted. Cutting forces, surface roughness and chip morphology are obtained. It is shown that cooling/lubrication conditions influence cutting force greatly while its effect on surface roughness is not obvious. The chip surface contacted with rake face under nitrogen gas is smoother than that under dry, but there exists nitrogen adsorption of the chip at higher speed.

Abstract: Drilling parameters have great influences on hole accuracy and defect production. In this study, single factor test is applied to obtain the relationship between the torque deviation and the spindle speed n at different feeds per revolution f_r. White Light Interferometer (WLI) is applied to measure the hole shape. Based on the frequency domain analysis of torque deviation, the cause of hole shape deviation is investigated. Relationship between the hole shape accuracy and drilling parameters is established, which can be used to predict the hole shape by analyzing the torque deviation. Moreover, the reasonable processing parameters can be selected to obtain drilling hole with ideal shape and satisfying production efficiency.

Abstract: This paper reveals the deformation and vibration properties of thin-walled component with and without paraffin. Deformation characteristics of the thin-walled titanium alloy component acting with transient cutting force were investigated by static analysis. Based on the milling experiments with and without paraffin, acceleration signals, deformation and surface roughness were measured and analyzed. The results show that paraffin reinforcement can significantly enhance the machining stability, improve the surface finish and reduce the distortion of workpiece.