Bubnovska I. Improving forge-rolling processes based on the modeling of the mechanics of shape change of blanks

The dissertation is devoted to the scientific and technical task on increase of efficiency of processes of rolling of preparations from aluminum alloys, development of new schemes of rolling and a technique of an estimation of deformability of aluminum alloys at cold rolling. The method of estimating the deformability of the workpiece material during cold rolling was further developed, taking into account the peculiarities of the change of the stress-strain state in different molding schemes. The model of accumulation of damages of material of preparation from aluminum alloys concerning definition of size of the used resource of plasticity and boundary deformations at monotonic and nonmonotonic cold rolling is offered. The regularities of the influence of active friction forces caused by the change of the roll diameter in the axial direction and its rotation on the kinematics of shape change, stress-strain state and deformability of workpieces in the process of cold rolling are established. The method of experimental research of plasticity of metals with maintenance of constant values of indicators of a stress state is developed. A method of manufacturing curved blanks has been developed. Within the developed simulation model of the method, the dependences between the relative compression and the accumulated deformation on the free side surface are obtained for use as an assessment and prediction of the possibilities of destruction of the workpiece. The theory of thermal processes and thermal deformations during rolling of aluminum alloy billets is developed, on the basis of which the contribution of temperature component to expansion and advance coefficients is estimated, influence of oxide film on thermal state in deformation center is determined and recommended temperature interval of roll heating is established.