Physical Simulation And Process Parameter Optimization Of Nickel-based Superalloy Machining

Nickel base super-alloy Inconel 718, having excellent comprehensive mechanical properties, is widely used in various industrial fields. However, in the cutting process of Inconel 718, the problem of big cutting force, high cutting temperature and serious work hardening does not make the quality of the workpieces guaranteed, therefore, study on the cutting mechanism with the aid of an appropriate method and the machining process parameters optimization is imminent.This paper firstly established velocity field model, strain field model and strain rate field model in the primary shear zone based on the non-uniform shear zone model, solved the shear angle which is a key parameter in these models using iterative method, and studied the influence of cutting parameters on these variables. However, the physical quantity in the process of deformation of metal cutting obtained by analytic method is very limited. In order to solve this problem,2D orthogonal cutting model and 3D real time turning model for nickel base super-alloy Inconel 718 were established based on Deform simulation platform and some key techniques of physical modeling and simulation of metal cutting.Three aspects of the research work on the Inconel 718 cutting process were completed based on 2D orthogonal cutting simulation model as below:Firstly, the forming process of serrated chip was simulated, the correctness of the simulation results was analyzed and contrasted by experimental data, the forming mechanism of serrated chip was studied with the help of cutting temperature, strain, strain rate and stress, and the influence of serrated chip formation on cutting process based on cutting force was studied; Secondly, optimized rake angle and cutting edge radius were obtained for targets of the lowest temperature and the minimum cutting tool stress, which can provide a preliminary reference for the optimization of cutting tool; And in the end, the formation process of residual stress was simulated, the correctness of the result was validated by experimental data, and the influence of cutting parameters on the residual stress was studied.The prediction model of cutting force and cutting temperature for turning processes of nickel base super-alloy Inconel 718 with the aid of Response Surface Methodology based on physical simulation data from 3D turning model was established, the response relation between these two physical quantities and cutting speed, feed rate and cutting depth was studied, and the correctness of the model was validated by turning experiment.A multi-objective optimization model of turning process for nickel base super-alloy Inconel 718 was established for the targets of the minimum cutting force, the lowest cutting temperature, the maximum material removal rate, the longest tool life and the minimum surface roughness which are restrained by the conditions of the spindle speed, feed rate, cutting depth and the power of machine tool and so on based on the ideas of Pareto optimal solution sets. The model was solved in MATLAB based on multi-objective genetic algorithm, and optimized process parameters, validated by simulation method, were obtained.The study of this paper not only further clarifies the cutting mechanism of nickel based super-alloy Inconel 718 but also provides quantitative reference for tool selection and process parameters formulation, which has strong application value.