Angular parameters of an unsymmetrical center of deformation during the rolling of metal powder

The angular parameters characterizing the deformation center for different schemes and conditions of asymmetry creation in rolling powders of metals and alloys are considered in the review. It is shown that the considered 4 types of asymmetry used for rolling compact materials (velocity, friction, geometric, and physical) can be applied to asymmetric rolling of metal powders, taking into account the characteristics of the compact material and powder. It is shown that to evaluate this cell, a number of angles developed to describe a symmetric deformation cell are used, plotted on a cross-sectional plane perpendicular to the roll axes (plane problem). The most studied was the rolling scheme on rolls of different diameters rotating at the same angular velocity with a vertical powder feed. It was found that during asymmetric rolling of iron powder on rolls rotating at the same angular speed but with different diameters, with an increase in the maximum normal contact stress from 200 to 500 MPa on rolls of larger and smaller diameters, the angle of the pressure curve onset increases from 11 to 16 and from 8 to 18 degrees, or by 45 and 125 %, respectively, while when rolling on rolls of the same diameter, it increases only by 18 %. This effect was previously observed in asymmetric rolling of ductile metals and alloys. Taking into account and studying the value of the angle of the pressure curve onset made it possible to characterize the process of asymmetric rolling, in particular, the effect of the asymmetry value. The existing dependencies that relate the angular parameter to other parameters of the deformation cell were analyzed. In addition, two new angles were introduced: the angle of inclination of the neutral section to the line of centers (β) for the rolling scheme on rolls of different diameters rotating at the same angular speed and powder is fed in the vertical direction and the central angle corresponding to the beginning of joint plastic deformation of powder and compact strip (αg), which corresponds to the intersection where joint plastic deformation of powder and strip begins. The values of these angles are not given.