Materials Science Forum Vols. 836-837

Abstract: A calculation scheme to gain the relationship between the thickness of shrink-fit holder and thermodynamic properties. Based on the theoretical analysis of fitting molder between shrink-fit holder and tool, then the thermodynamic properties of the shrink-fit holder and cutting tool such as contact pressure, equivalent stress and deformation are analyzed at different thickness of shrink-fit holder in static, under cutting force and inducting heating by using the finite element software ANSYS. The results show that the total contact pressure and maximum equivalent stress increased and the minimum thermal displacement difference decreased with the increase of holder thickness. Under the action of cutting force, the contact stress on the tool holder no longer uniformed and the maximum contact stress significantly increased, cutting tool also deformed. Finally a method to determine the reasonable holder thickness is given and it has a practical guiding significance for the design and selection of the shrink-fit tool holder.

Abstract: Thermal deformation of large size hydrostatic bearing rotary workbench is the most direct factor that affects the machining accuracy of work-piece. The thesis puts forward the method of adding reinforcing plate structure to restrain the workbench thermal deformation, establishes three-dimensional supporting workbench model, with finite element method and sequence of fluid-solid coupling technology have carried on the thermal deformation calculation workbench, and reveals the influence law of different installation position of rib plate on the workbench thermal deformation. The results of the study shows that the method of adding reinforcing plate structure to reduce the thermal deformation of hydrostatic bearing worktable is feasible, and determine the optimal position of reinforcing plate by comparing different results.

Abstract: In the meso-scale machining, feed rate, grain size and tool edge radius are in the same order of magnitude, and cutting process is often carried out in the grain interior and grain boundary. In this paper the meso-cutting process of hot-rolled AISI1045 steel is studied and its metallographic microstructure is analyzed for the establishment of multiphase models which incorporate the effect of ferrite and pearlite grains. In order to discover the applicability of multiphase models to the simulation of meso-cutting, three contrast simulation models including multiphase model with rounded-edge cutting insert (model I), multiphase model with sharp edge cutting insert (model II) and equivalent homogeneous material model with rounded-edge cutting insert (model III) are built up for the meso-orthogonal cutting processes of hot-rolled AISI1045. By comparison with the experiments in terms of chip morphology, cutting force and specific cutting force, the most suitable model is identified. Then the stress distiribution is analyzed. And it is found that multiphase model with tool edge radius can give a more accurate prediction of the global variables and reveal more about these important local variables distribution.

Abstract: Rectangle part is the foundation of irregular part layout, about which domestic and overseas scholars have studied a lot and have put forward many algorithms. Based on a careful study of these algorithms in the paper, it is determined to solve the rectangle packing problem with genetic algorithm analysis. Different from the formerly used the genetic algorithm optimization layout, the algorithm of this paper stresses optimization localization rule in order to solve layout problem with the advantages of global searching ability of genetic algorithm. This algorithm sets the utilization ratio of the maximum area of capacity as the goal, after confirming the priority of deposition sequence of rectangle, in view of the locating rule of rectangle packing, based on feasible region and by introducing the method of attractive factors, optimizing the calculation for each parameter of placement function by utilizing genetic algorithm.Positioning function of the structure of this paper by changing the parameter value can cover the previous golden horn strategy, the lower left corner strategy, down the steps such as positioning method. Use VC programming to realize automatic two dimensional rectangular layout systems, the algorithm and example verification, the precision of parameter on the result of layout, the number of attractor for layout results, and the influence of parameter values for different rectangular piece of regularity. According to different rectangular block configuration, layout scheme can be better and faster.

Abstract: High-speed chuck is an important component of high speed machining tooling system. Its properties directly affect the performance and processing quality of advanced numerical control machine. Using the finite element method, the research analyzed influence of inertial centrifugal force caused by unbalance on the dynamic characteristics of HSK hydraulic clamping chuck tooling system and systematically revealed variation of shank, chuck and blade point displacement. It is found that blade point, as well as chuck and shank displacement response amplitude of tooling system rises as a whole with the increase of excitation frequency; the dynamic displacement response increment shows linear growth with unbalance amount, which provides a theoretical basis for optimum design and balancing control of HSK hydraulic chunk tooling system.

Abstract: Due to the transition region with different hardness, the milling process of assembled hardened steel die is prone to generate flutter, which is hard to ensure surface integrity of workpiece. By establishing the finite element model, the milling process of assembled hardened steel die was calculated by the finite element method. Effects of cutting parameters on milling force and milling temperature were achieved by the above finite element analysis. The laws of the stress and the thermal field distribution in the assembled transition region are analyzed and discovered. The analysis results demonstrate that milling force and milling temperature of the transition region changes in step leaping way. There is a close relationship between processing stability and cutting parameters. The stress and the thermal distribution of the transition region have a significant difference due to the changes in material hardness.

Abstract: In high speed machining superalloys processes, tool wear is strongly influenced by the cutting temperature and contact stresses. Finite element analysis of machining can be used as a supplementary to the physical experiment, this paper provides investigations in 2D and 3D finite element modeling and simulation of prestressed cutting for GH4169 superalloy, a tool wear model for the specified tool and workpiece pair is developed based on the Usui's wear model, furthermore, tool temperature, wear rate and nodal displacement on the face of tool in prestressed cutting of superalloy is analyzed under various prestress condition and cutting parameters, and Python language is adopted to modify the Abaqus code used to allow tool wear calculation and tool geometry updating. The results of the simulation indicate that the tool wear rate increases with the increase of cutting time, and the influence of the prestress to tool wear in prestressed cutting process of shaft part is unremarkable.

Abstract: A unified oblique cutting force model for flat end mills is developed. In this model, the cutting force is bridged among cutter geometry, material properties and cutting parameters. The cutter angles, material parameters and cutting parameters are the only inputs so that the model is applicable for different cutter-workpiece combinations and cutting parameters. The parameters in the model are solved by the geometric relations, applying Maximum Shear Stress Principle and Stabler’s chip flow rule. The material parameters are identified in a new method with orthogonal milling tests. The simulation results of the proposed model are in good agreement with experiments.

Abstract: With pelton turbines and other complex three-dimensional structure cavities that contains various shaped surfaces and all kinds of larger curvature, the three-axis CNC machine with a tool rotary to achieve the four coordinate overall Pelton CNC machining. According to processing characteristics of pelton runner, the paper determines the selection of materials and the overall structure of the tool. And the appropriate way of milling and milling parameters are made. The overall processing program and processing parameters of pelton runner are designed on this basis. The feasibility of the process and cutting route are verified by the simulation of cutting route and experiments.

Abstract: Plunge milling cutter withstanding greater loads in heavy milling can cause tool breakage, cutting vibration, even chatter. Firstly, geometric model of plunge milling cutter on various combinations of axial rake angle and radial rake angle are established. Secondly, with combination different axial rake angle and radial rake angle of plunge milling cutter under static load, the amount of deformation plunge milling cutter are calculated by finite element analysis. Finally, the plunge milling cutter first six natural frequencies are given in plunge milling cutter modal analysis with finite element analysis. The results show that minimum total deformation of plunge milling cutter is given with the axial rake angle 5° and radial rake angle-5 ° of the cutter and when the tool working at frequencies up to 10012HZ has caused vibration within the XY plane.