Research On Force Model Covered With Material Damage

The cutting force is one of the important physical processes in metal cutting, directly influences the quality of the work-piece, the tool wear and machine power consumption. The cutting force is the basis of selecting tools, fixtures, and cutting parameters.Due to the high strain, strain rate and temperature in high speed machining, the material of the work-piece will suffer adiabatic shear instability. However, The current cutting force model, did not fully consider the impact of material damage caused by adiabatic shear, leads to a optimize difference between the theoretic model and the practical machining.In this article, considers the adiabatic shear damage mechanism of metal cutting, so the cutting force model can fully consider the impact of material properties. The main contents of this article are as follows:Firstly, gives an orthogonal cutting test of AISI1045 steel, to obtain the relations among the cutting force, the chip morphology and the damage of serrated chip. The result shows, the cutting force varies with different chip morphology, the chip morphology is related to the phenomenon of adiabatic shear. The increase of thermal softening caused by high temperature and the material damage caused by ductile fracture have great influence of cutting force.Secondly, with understand of the relationship between the material damage and cutting force, a promotion model of Johnson-Cook model is presented. The new model contains damage variable, considering the adiabatic shear during the high speed machining. Taking the new model into the current cutting model, obtains a new cutting force model. The new model not only considers the material strain rate, the thermal softening, also considering the adiabatic shear damage to the cutting force.Finally, take AISI-1045 steel as an example, use MATLAB to program, calculate the cutting force of different parameters, make a comparison with experiment results and cutting force without considering material damage. The comparison suggests that the difference between the theoretical value of the promotion model and the experimental result is smaller. The promotion model is more accurately to predict the cutting force during the high speed machining than the conventional model.In this paper, uses the material model covered damage to promote the theoretic model of cutting force, which increases the accuracy of the cutting force prediction and expands the use of cutting force model in high speed machining. The result of this paper is helpful to understand the mechanism of the high speed machining and to promote the study of high speed machining technique.