Key Engineering Materials Vols. 589-590

Abstract: Based on the Merchant shear angle theory, two-dimensional high-speed orthogonal cutting experiments with an ‘OXCUT’ flow stress inverse procedure were used to determine the Johnson-Cook constitutive constants of the AISI 1045 steel (195HB). The constitutive constants obtained in the strain range 1.3-1.4 and large strain rate range 6106-7106/s. It is verified by experiments, and the result shows that the cutting forces are within the permissible error range. Compared the constitutive model with Hu’s, the cutting forces of this constitutive model of FEM are closer to the measurement, while the feed force has a relatively larger gap.

Abstract: In the machining process of large parts, the dynamic alternating loading suffered by heavy carbide insert is very large, so the fatigue failure of the insert is serious. Through the analysis the effect of dynamic alternating force - thermal load on insert’s crack, and the fatigue crack experiment of inserts under dynamic alternating loading will be done, the formation conditions and distribution law of fatigue cracks can be researched under the effect of dynamic mechanical shock and thermal shock. And the fatigue crack will be theoretical analysis through the fatigue curve in the range of test cutting parameters. It can provide effective basis for the optimizing the heavy-duty cutting parameters and reducing the fatigue crack failure of heavy-duty cutting insert.

Abstract: Titanium alloy is widely applied in various fields, but it’s a sort of difficult-to-cut material. In this paper, DEFORM-3D is used to carry on a simulation of PCD tool milling Ti6A14V. Variation curves of cutting temperature and cutting force are obtained by changing cutting speed, feed per tooth and axial cutting depth. Further, the effect of cutting parameters on cutting temperature and cutting force is revealed. The research shows that cutting temperature and cutting force increase with cutting parameters. In addition, single factor experiments are conducted to verify that the results of the experiments are in consistent with those of the simulation, and that the simulation model is correct. The results will provide new methods for studies of cutting temperature and cutting force of PCD tool milling Ti6A14V.

Abstract: The superalloy parts in the aeronautical field demand high reliability, which is largely related to surface integrity. Surface integrity generally includes three parameters, such as geometric parameter, mechanical parameter and metallurgical parameter. The paper presents the influence of cutting speed on surface plastic deformation and white layer formation through orthogonal milling of FGH95 superally material. The influence of cutting speed on grain refinement of machined surface is also investigated. It is found that cutting speed has significantly effect on the surface metallurgical characteristic microstructure. The increasing of cutting speed creates severer plastic deformation. Surface plastic shear strain increases with the increasing of cutting speed, while the depth of plastic deformation decreases on contrary. White layer thickness is increased with the increasing of cutting speed. Through statistical analysis for grains number, it can be drawn that the higher the cutting speed, the more serious grains refinement.

Abstract: In this paper, high speed milling experiments on Ti6Al4V were conducted with coated carbide inserts under a wide range of cutting conditions. The effects of cutting speed, feed rate and radial depth of cut on the cutting forces, chip morphologies as well as surface roughness were investigated. The results indicated that the cutting speed 200m/min could be considered as a critical value at which both relatively low cutting forces and good surface quality can be obtained at the same time. When the cutting speed exceeds 200m/min, the cutting forces increase rapidly and the surface quality degrades. There exist obvious correlations between cutting forces and surface roughness.

Abstract: A generalized cutting mechanics model is proposed for milling processes with solid end mills and inserted cutters. The unified mathematical model is employed for the description of the solid milling flute and insert on a reference tool body. The friction and normal forces acting on the rake face are transformed into milling coordinates using a general transformation matrix by simply assigning operation specific parameters. The generalized model can be used to predict and optimize the machining operations including solid end mills and inserted cutters.

Abstract: Ni-based super-alloy GH4169 that is most widely used in aerospace is one of the most difficult-to-cut materials, which can be machined by Polycrystalline Cubic Boron Nitride (PCBN) tool. In this paper, the cutting process of super-alloy GH4169 with PCBN tool is researched by simulation, combing with the comparison and verification of experiment. The change rules of cutting temperature and force under different cutting parameters are obtained in this study. The reasonable parameter ranges of high efficiency cutting are proposed in cutting parameter optimization, in order to provide a reference for high efficiency machining of super-alloy GH4169 with PCBN tool.

Abstract: In heavy-duty cutting, large chips produced are wide, thick and of complex shapes. If the large chips are not controlled reasonably they will heavily influence the machining efficiency. This article researches on the generation process of large chips, and is combined with the research method of finite element simulation to establish curling model of large chips in heavy-duty cutting process. Through analyzing the fracture strain and cut strain suffered by the chips in the curling process of large chips and enlarging the large chips using electron microscopy, the generation and curling deformation law is revealed. And analyzing generation and curling mechanism of large chips can provide theoretical basis for the generation and control of ideal chips in heavy-duty cutting process.

Abstract: By 3D finite element simulation for temperature field and tool wear of SiCp/Al metal matrix composites under the condition of high speed milling, we draw a conclusion that the most significant influence on cutting temperature is cutting speed, less is feed rates, the minimum is cutting depth, which is exactly the same as the influence law of ordinary metal cutting. In the course of high-speed milling SiCp/Al by PCD tools, the higher the cutting speed is, the bigger wearing depth of tools is. When v=300m/min, ap=0.5 mm, f=0.3 mm/r, the transient temperature in the milling would reach to 619°C. Such a high temperature can cause graphitizing wear of the PCD tools. Because of the effectiveness of the simulation’s conclusion, it is vital significance to the reasonable options of cutting parameters and the prolongation of tool life.

Abstract: In milling process, cutting force is the main cause of machining deformation, and in machining of thin-walled parts, machining deformation is the major factor for machining error. In this paper, through finite element analysis software ABAQUS, three-dimensional simulation analysis on the machining of SiCp/Al composite thin-walled parts with a polycrystalline diamond tool have been carried out. It reveals the influence of radial depth of cut, cutting speed, and feed per tooth on cutting force. Analysis results show that: higher speed, small radial depth of cut and moderate feed per tooth can effectively reduce cutting force and inhibit deformation. In addition, a comparison is made between analysis results of milling force and high accuracy milling force prediction model, results from the two methods are similar.