Study of the jet-flow rate of cooling in machining part 2. Simulation study

Abstract

In this study, the effect of the jet-flow rate of cooling on the temperature distribution in the cutting region of machining is investigated through numerical simulation using the cooling heat-transfer models developed in Part 1. The tool, chip, workpiece and coolant in the cutting process are considered as one system of heat generation and transfer. Heat generation from all sources in the cutting regions, including the primary and secondary plastic deformation zones of the work material, the tool-chip and the tool flank-work interface, is predicted from the workpiece material properties, tool geometry, cutting conditions and, cutting forces, based on realistic modelling of the cutting process. The temperature distributions throughout the tool, chip and workpiece in the cutting of steel under different cooling conditions are calculated using the finite-element method. The results indicate that in cutting with overhead-jet cooling or flank-jet cooling, the temperatures in the cutting regions near to the boundary surfaces exposed to coolant can be further reduced when the jet-flow rate of cooling is increased. However, in both cooling methods, the corresponding percentage increases in reduction of the temperature in the main cutting regions, such as the tool-chip interface and tool flank-work interface, are much smaller compared to the percentage increases in the coolant flow rate. To achieve a small percentage increase in the reduction of temperature in the main cutting regions by increasing the coolant flow rate, a much larger percentage increase in the flow rate is required. The natures of overhead-jet and flank-jet cooling are such that by increasing the coolant flow rate in the processes the effectiveness of cooling can only be improved up to a limit, which latter depends on the physical properties of the coolant and the fraction of the heat conducted from the main cutting regions to the surfaces exposed to coolant.