Abstract
The article describes the influence of the scale formation and the die angle on the heat transfer in the drawing out process. The die angle affects the surface of contact of the ingot with the anvils and it results the heat flux transferred to the air and tools. In order to describe the heat transfer boundary conditions in the zone of material contact with the dies the secondary scale formation as a function of time and a forged steel surface temperature have been taken into account. The scale thickness has been calculated on the basis of the experimental equation defining the growth of the weight of scale while steel cooling in the air. It has made it possible to vary the heat transfer coefficient as a function of process time and the scale thickness. The dependence of the heat transfer coefficient on the type of anvil has been determined by taking into account the die angle and the deformation ratio during the drawing out operation. The empirical functions have been established to approximate the ratio of material contact with the anvils. The tape of anvil and the deformation ratio have been taken into account. On the basis of the developed heat transfer boundary conditions, the temperature fields of the forged shaft have been calculated.