抄録
Built-up edge (BUE) formation in machining maintains a profound effect on the cutting operation, such as cutting forces, cutting temperatures, tool wear, tool life, cutting vibration, surface roughness and the geometric dimensions of machined products and so on. Recently, attempts have been made to use the BUE as the tool cutting edge/wedge to optimize machining, extend the tool life and so on. In order to have a clearly understanding of BUE evolution, cutting experiments were performed on aluminum alloy A6063-T6 and low carbide steel SM490A using the cemented carbide tool over a wide range of cutting speeds. The cutting speed of BUE formation spans just a small range of the cutting speed under low cutting speed and disappears with increasing the cutting speed, which is found to be ascribed to the decrease of cutting force and thermal softening effect that caused by increasing cutting speed. Further microscopic observations reveal that the plastic shear and shear rate of secondary shear zone is significantly related to the formation of BUE which increases with increasing the cutting speed. Since the chip compression ratio is an important parameter to characterize the chip plastic deformation, the relationship between the chip compression ratio and evolution of BUE is considered. In this work, a new theoretical damage model is developed to predict the evolution of BUE formation, in which the reduction of material properties due to the thermal diffusion had been considered. And the model validation is performed by comparing the experimental results with the simulations for aluminum alloy A6063-T6 and low carbide steel SM490A, which clearly show that the proposed damage model is able to predict the periodic evolution of BUE. Not only the cycle time can be predicted, but also it makes a more clearly understanding of the evolution of BUE formation mechanism and its effects.
