THE INFLUENCE OF LUBRICATING FLUID COOLANT ACTION ON GRINDING TEMPERATURE

The authors obtained the one-dimensional (in the coordinate) mathematical models to determine temperature field during grinding from the surface layer depth and in the course of time. These models take into account two types of cooling: cooling due to thermal conductivity of the processed material at zero heating and cooling due to the impact of lubricoolant on the processed surface. In the first case, the boundary conditions of the second kind at the stage of heating and application of method of thermal fields superposition were used; in the second one, the boundary conditions of the second and the third kinds were used in the heating and cooling area, respectively. In the second case (forced cooling), it became possible to eliminate a certain contradiction, which is the characteristic of two-dimensional temperature field model when the boundary conditions of the second and the third kinds acted simultaneously in the phase of heating. Within this model, the cooling is caused not only by the lack of heating in the cooling area, but also by heat exchange between the processed (heated) surface and the cutting lubricoolant, and the lubricoolant in this temperature model has its own temperature taken into account during the cooling process. Temperature distribution throughout the surface layer depth at the end of heating phase is the initial condition for determination of temperature field on the stage of cooling at any time measured from the end of heating phase. The authors determined the influence of lubricoolants cooling action not only on the surface temperature, but also on its distribution throughout the depth of the surface layer at any time. The study confirmed that the temperature of material deep layers may exceed the temperature of upper layers during the cooling phase, i.e. the change of heat flow direction takes place that influences the nature of structural and phase transitions of the material surface layer.