Materials Science Forum Vols. 800-801

Abstract: High speed cutting technology has become one of the most important technology in manufacturing of automobile panel dies. The range of each motion axis of numerical control equipment is large and the entire process system exist certain differences of the dynamic characteristic cause of the large type surface size of automobile panel dies. And affect the stability of the processing conditions directly. In this paper, different locations dynamics of large CNC machining equipment was analysed, then getting the influence of processing on the dynamics of the processing position. Simulation results show the machine dynamic characteristic mainly affected by the working position of the spindle box, and the location of the workbench has smaller impact. In the low speed mode, the stiffness characteristics of the spindle box in the operating position on both sides is better and in the high-speed mode the stiffness characteristics is better in the right side of the spindle box. When the table near the right end position in X, Y have weak stiffness near 90Hz.It has weak stiffness in the left side of table near 80Hz and in middle position it has weak stiffness near 80Hz or 140Hz . In the cutting process to provide guidance for the selection of appropriate processing location and process parameters.

Abstract: The service performance is seriously effected by milling machined surface integrity of auto hardened steel mould. Basing on the microscopic damage evolution theory and hardened steel mould material micro-voids cell model, according to the service process load condition of hardened steel milling machined surface, surface microscopic damage evolution analysis had been conducted, surface evolution characteristics was obtained under different shapes void cell. Through comparative analysis the change law of damage evolution internal variable under different shapes void cell can know: respect to the ideal spherical, when the change of void volume fraction and the degree of matrix material yield were considered, the oblate hole more faster and the prolate hole more slower, which provide a further prediction for surface damage.

Abstract: In this paper, a cutting force model in ball end milling of mold cavity corner is established. Based on infinitesimal milling force model, cutting element of ball end milling cutter is treated as equal diameter end milling cutter, then determine the location of points when the micro-element participated in the cutting, and the tool-workpiece contact area and cutting range is determined. Thereby a complete milling force model in corner machining with ball end milling cutter is established.

Abstract: Mould surface loading state is one of the most important factors which would affect the mould performance in the course of service. According to the established hardened steel milling surface geometry model, a bending forming numerical simulation of hardened steel milling is conducted, the influence law of service process surface load state is analyzed under machined surface geometry structure which is formed by different milling parameters. The research results show: surface load concentrated area is mainly focusing on mould edge transition and fillet in the course of service; the surface geometry structure has an important influence on the mould service load in the course of service, service load more smaller which is more helpful to improve the mould service performance in the course of service.

Abstract: The three-dimensional finite element modeling and experimental validation of plunge milling of stainless steel (1Cr13) are presented. The commercial software Deform 3D applied for the finite element modeling is studied the effect of feed rate per tooth (f_z) on the cutting forces and the temperature fields. The formation of chip in the finite element model is formed by local adaptive remeshing technique. The feed rate per tooth (f_z) significantly affects the cutting forces, but slightly influences the maximum temperature of the chip.

Abstract: In traditional model of high-speed cutting, each modeling or modify process, material parameters input, boundary conditions set take up a lot of time, the solution process has blindness and not easy to operate. this article uses the python language, based on ABAQUS to secondary development of cutting simulation model in pre-treatment, establish exclusive two-dimensional cutting simulation interface, realization the parametric settings of tool angle, the size of the tool and the workpiece, cutting parameters, parametric design can shorten the time of modeling, and lay the foundation for the establishment of the high efficiency and high accuracy of the simulation model.

Abstract: This paper focus on automobile panel dies and moulds, studying the sliding friction phenomenon between tools and workpiece caused by inadequate margin adopted during finishing. Based on this, the forecasting model of the limit milling depth is built with the consideration of tool deformation. Further on, the model built is tested by milling experiments with different radii of curvature, and providing the evidence for adoption and optimization of margin of steel finishing.

Abstract: Dynamometer has a extensive application in high-speed milling. The high frequency dynamometer is a kind of strain-gage dynamometer and produces a relation between the cutting force and voltage. And the relation can be expressed as a conversion matrix model which makes a great impact on the results of measurement. Taking into account cross-sensitivity and point effect at the same time, a new conversion matrix model for the high frequency dynamometer was established in order to improve the accuracy of dynamometer and the dynamometer has been subjected to calibration experiments to obtain conversion matrixes of the model. Finally, a series of high speed milling experiments were conducted. And the results obtained showed that the dynamometer by adopting the model could measure the cutting forces and have a higher accuracy.

Abstract: This paper presents the prediction method of cutting force and dimensional error of Ti6Al4V alloy thin-wall components in end-milling operations. Based on the FEM simulation software and force-model, machining deformation was predicted by two kinds of FEM models, and then compared with the measured data. Results obtained from the proposed models and the tests show that the coupling model of thermal-mechanical having better agreement with the experimental results. Besides, the test results also prove the new tool-path pattern proposed in this paper is useful to reduce the machining error.

Abstract: Aero-engine alloys (also as known as superalloys) are known as difficult-to-machine materials, especially at higher cutting speeds, due to their several inherent properties such as low thermal conductivity and their high reactivity with cutting tool materials. In this paper a finite element analysis (FEA) of machining for Incoloy907 is presented. In particular, the thermodynamical constitutitve equation (T-C-E) in FEA is applied for both workpiece material and tool material. Cutting temperature and cutting force are predicted. The comparison between the predicted and experimental cutting temperature and cutting force are presented and discussed. The results indicated that a good prediction accuracy of both principal cutting temperature and cutting force can be achieved by the method of FEA with thermodynamical constitutitve equation. Keywords: Incoloy907,Simulation, Thermodynamical constitutitve equation