Optimization of process parameters for residual stress analysis in turning alloy steel under high-pressure coolant jet condition

Abstract

Machining induced residual stress is an important aspect of study on controlling machining parameters to get desired product quality as the functional behavior of machined component can be enhanced or impaired by it. Besides, high pressure coolant (HPC) supply during machining is considered as favorable cutting environment to get better machinability indices over dry condition. In the purpose of gaining superior product quality it would be beneficial to study the effect of residual stress under HPC condition along with rational setting of machining parameters. This study aims at finding the optimum cutting conditions and monitoring the residual stress in turning of 42CrMo4 alloy steel by HPC lubrication. On the basis of experimental results this paper develops empirical models for predicting cutting temperature, surface roughness and tool wear in terms of workpiece hardness, cutting speed and feed rate using multiple regressions modeling method.The results of ANOVA prove that the models could adequately describe the performance indicators within the limits of the statistical factors. Then, multi-objective optimization approach based on genetic algorithm has been employed to get the optimal setting of process parameters that simultaneously minimize cutting temperature, surface roughness and tool wear.It was found that the optimum results provide consistent results compared to experimental measurements. The optimum results was then used in finite element method based simulation of residual stress. This paper presents a 2D finite element model based on Arbitrary-Lagrangian-Eulerian formulation using ABAQUS software. The Johnson-Cook material and damage model have been used for chip formation. Based on this model the effects of coolant application on temperature variation were investigated in simulations. The temperature distribution of chip-tool interface in simulation shows a good agreement with the measured cutting temperature. Simulation results offer an insight into workpiece hardness and cutting parameters influence on the induced residual stresses. Based on the simulation results, cutting speed and workpiece hardness show trend for machining induced residual stress. However, more investigation is needed in determining a trend for the feed rate influence.