Determination of rolls diameter for screw-rolling mills

The problem of determining the maximum diameter of working rolls is typical for screw rolling mills that have more than two working rolls. Precise determination of the working roll diameter is especially important for three-roll mills, which are widely used in such industries as rolling and calibration, and radial-shear rolling mills operating at large feeding and rolling angles. Typically, the diameter of working rolls is determined in a constructive way or using 3D modeling. These methods are quite complex, require special skills, and do not allow investigation of the influence of main tuning mill factors such as feeding and rolling angles. There is a calculated method for determining the diameter of the roll barrel for a three-roll mill, but it is applicable for mills working at feeding angles of up to 10 degrees and rolling angles of 4  –  7  degrees. In conditions of radial-shear rolling, this method is not used, since it does not take into account the influence of feeding and rolling angles on which the conditions of the deformation process, manufacturability and quality of the products depend. The article considers a more general method for determining the diameter of working rolls of three or more rolling mills, taking into account their rotation at the feeding and rolling angles. The relationship between diameter of the rolls, their number, minimum diameter of the deformation center, the feeding and rolling angles are shown, which makes it possible to evaluate the structural capabilities of both three and four-roll rolling mills. The results of the presented work make it possible to expand the possibilities for further studies of the technology and equipment of three-roll screw rolling mills for the production of solid and hollow products using completely new deformation modes for the processes of rolling out hollow products of their reduction as well as radial shearing rolling. Importantly, it is possible to supplement existing knowledge about the change in geometry of deformation center, and also to predict geometric parameters of the working rolls of the projected multi-roll mills for given rolled products sizes.