Simulation And Experimental Study Of Micro Milling Machining Deformation Based On Thermal-Mechanical Coupling

With the technology development and social progress, high-precision micro-parts are widely applied. Micro-milling technology is an important technology in the field of micro-parts manufacturing, its processing performance, detection and analysis method has been widespread concerned. In micro milling process, cutting heat and temperature distribution on the workpiece, cutting tool and cutting process has important influence. So it is necessary to simulate the temperature field of micro milling process and study on the influence of cutting heat on workpiece deformation and the roughness of machined surface.Aiming at this problem, this paper studies the heat conduction law and the temperature distribution of the workpiece in the micro machining process. In order to realize the understanding of the heat transfer process and the machining precision of the workpiece.The main research contents of this paper include the following aspects:(1) Based on the principle of heat source, the heat transfer process of milling is analyzed, and the simplified model of the heat transfer is established according to the principle of temperature field. The heat transfer process of the complex process is simplified to the finite surface heat source. The temperature field model of the workpiece model under the action of the shear surface heat source is established. At the same time, on the basis of the inverse method, the shear plane heat source intensity value of the shear surface is obtained by using MATLAB programming. On the one hand, the intensity of the heat source is calculated by the known parameters of the theoretical model and the instantaneous temperature value is obtained. On the other hand, the value will be used as the finite element simulation model of the cutting thermal load. In order to verify the validity of the model, a micro milling experiment was designed, and the temperature of the workpiece was measured by thermocouple in the process of experiment. At the same time,the temperature and the theoretical prediction results are compared, and the error analysis of the actual cutting process is carried out.(2) Simulation and forecasting model of workpiece temperature field under different cutting parameters by using finite element software ABAQUS. Numerical calculation of surface heat source intensity values will serve as the finite element model of the cutting heat load, in every time step to calculate the heat load for the instantaneous cutting area unit,when the cutting heat load moving to next instantaneous cutting area, cutting heat loads on a step before the loading of unloading operation; in addition, using unit kill technology to simulate the milling material removal process, the realization of the milling process is discretized in time and space. The accuracy of the simulation model is verified by comparing with the experimental measurements.(3) The experimental platform is set up, which is used for the on-line measurement of the three force and the instantaneous temperature. The different design parameters of groove milling experiments acquired under different cutting parameters of cutting force data and a brief analysis of the influence of cutting parameters on cutting force, collected at the same time under different cutting parameters of the instantaneous temperature value is obtained, analysis of the cutting parameters on cutting temperature effects of, and with the simulation temperature value and temperature values are compared, to verify the simulation model and the temperature rise the accuracy of the theoretical model.(4) By KEYENCE and white light interferometer is used to measure the workpiece after machining deformation value and machining precision value, discusses the spindle speed, under different cutting parameters, feed speed and axial depth of cut groove deformation value and groove bottom surface roughness value change rule, cutting force and cutting temperature as two main influencing factors, to analyze the reason of the deformation of the workpiece and the processing precision of and the theory basis for the actual milling parameters selection.