Papers by Keyword: Orthogonal Cutting

Abstract: An orthogonal cutting model for investigating indentation type cutting of soft tissue was established, and the cutting force model was constructed theoretically based on fracture mechanics. A planar biological soft tissue cutting experimental setup was designed and developed to realize soft tissue cutting. Cutting experiments using orthogonal cutting blades were performed on fresh porcine liver at different cutting speeds. It was experimentally shown that the cutting speeds and the blade rake angles have significant effects on the penetration force and cutting force. Finally, a regression equation was obtained to explain the relationship among cutting force, cutting speed, and rake angle. These findings provide new insight into the biological soft tissue cutting.

Abstract: It is necessary for cutting simulation to determine the friction model at the tool-chip interface suitable for metal cutting process. Cutting force experiments in orthogonal turning titanium alloy TI6AL4V are carried out with cement carbide tool KW10. The Coulomb frictions at the tool-chip interface are calculated based on measured cutting force, and the friction model is regressed, where cutting speed and feed rate are presented.

Abstract: Identification of workpiece material constitutive parameters for their application in the simulation of metal cutting process has been a hot research spot for long. This paper proposes a methodology to address this problem using orthogonal cutting tests and Genetic Algorithm (GA). First, an analytical model which calculates the dynamic characteristics occurring in the primary shear zone is introduced; then, orthogonal cutting tests are carried out, to record the following mechanical characteristics with the analytical model: shear stresses, shear strains, strain rates, cutting temperatures; afterwards, GA is employed to obtain the constitutive parameters from these characteristics; at last, the finite element method (FEM) simulations of the cutting tests are performed to evaluate the predictive accuracies of the obtained parameters. In this paper, a Japanese brand steel SCM440H is used as the workpiece material, and the simulation results of its constitutive parameters show good agreements with the experimental data, which renders the feasibility of the proposed methodology.

Abstract: This paper presents a rigid-plastic finite element method for orthogonal cutting process by adopting Lagrange method. The rigid-plastic FEM analysis model is established and the rigid-plastic FEM analysis toolkit was developed. Meanwhile, two relevant key problems are discussed systematically, including the rule of chip-workpiece separation and the criterion of tool-chip separation. At last, a simulation example of planing an aluminium alloy (ZL-301) workpiece was conducted. The effects of the cutting stroke, the tool rake angle and the friction coefficient on chip were observed. The numerical simulation results have a good agreement with their experimental ones. It is indicated that the presented FEM model and algorithm are efficient and correct.

Abstract: Cutting force is an important parameter in machining. The static balance method and experience formulas had been adopted to find its value, but the theoretical calculated value is not good agreement with the experimental value for the same set of cutting conditions. In practical machining, the cutting tool has obvious impact effect on workpiece, so a dynamics analytical model for cutting process is established in this paper. Based on the proposed solution, a new formula for cutting force has been obtained. The suggested formula has shown to correspond well with the experimental data.

Abstract: A new finite element simulation model based on two trochoidal tool-paths was constructed, and was used to simulate a full immersed milling with three flutes cutter. In this FEM model, the special method used here is to construct two trochoidal curves at the beginning with an offset value which is just equal to the feed value per tooth. These two linked trochoidal curves represent tool paths generated by two flutes respectively so as to construct the workpiece model. Cutting forces in the feed direction and in the normal direction were analyzed in detail. A verifying experiment shows this simulation is credible in general. This method can also be applied into situations of milling with more flutes such as face milling.

Abstract: Orthogonal cutting experiments of Fe-36Ni invar alloy are performed. The change of chip morphology with cutting conditions are investigated through metallurgical observation, and the critical cutting speed of adiabatic shear for Fe-36Ni invar alloy at different cutting depths and rake angles are given. In addition, the characteristic of chip deformation before the occurrence of adiabatic shear is also analyzed. The results show that the critical cutting speed decreases with the increase of cutting depth and hardness, but increases with the increase of rake angle. The deformation coefficient tends to a constant value with the increase of cutting speed.

Abstract: FEM implicit formulation shows specific limitations in processes such as cutting, where large deformation results in a heavy mesh distortion. Powerful rezoning-remeshing algorithms strongly reduce the effects of such a limitation but the computational times are significantly increased and additional errors are introduced. Nodal Integration is a recently introduced technique that allows finite element method to provide more reliable results when mesh becomes distorted in traditional FEMs. Furthermore, volumetric locking phenomenon seems to be avoided by using this integration technique instead of other methods, such as the coupled formulations. In this paper, a comparison between a “classical” FEM simulation and the Nodal Integration one is carried out taking into account a simple orthogonal cutting process.

Abstract: A material model is a prerequisite to the modelling of machining processes. Owing to its versatility, the Johnson-Cook model is commonly used for machining simulations. Determination of the model parameters from experiments is challenging due to the large variations of strains, strain-rates and temperatures which lead to several problems. State-of-the-art experimental methods have to rely on data obtained from much lower strains and strain-rates than those encountered during machining. In this paper, an inverse method of identifying Johnson-Cook parameters from machining experiments is described. A fnite-element model of the machining process was created and a particular Johnson-Cook parameter set was taken from literature for the simulation. The Levenberg-Marquardt Algorithm was used to re-identify the material parameters by looking at the Chip-morphology and the Cutting force evolution. It is shown that the optimisation parameters and error function must be chosen carefully in order to achieve better solutions at lower computational expense.

Abstract: The present paper reports the results obtained investigating surface work hardening in turning as a function of cutting speed, feed rate and tool wear. An experimental campaign was carried out using AISI 304 steel as workpiece material. Pipes 4 mm thick were machined under orthogonal cutting conditions. Tools with flat rake surface were adopted and dry cutting conditions were taken into account. Cutting speed and feed rate were varied and the tool wear was monitored using a CNC visiomeasuring machine. The tool wear was related to the workpiece strain hardening. Starting from micro Vickers test data, an analytical model representing the strain hardening behavior along a workpiece section was defined. In addition, a Fortran subroutine for the simulation of strain hardening by means of a 2D FEM code was implemented.