DEVELOPMENT OF TECHNOLOGIES FOR HOT PRESSING OF RODS MADE FROM 7075 ALUMINUM ALLOY ON A RADIAL­SHEAR MILL OF A NEW DESIGN – NUMERICAL MODELING

The paper proposes a radial shear mill (RSM) of a new design, which allows manufacturing metal rods of small diameters or wires with a fine-grained structure. The paper presents the results of modeling the evolution of the structure during hot rolling-pressing of aluminum alloy 7075 on the RSM. Mathematical modeling of the technological process was carried out using the MSC.SuperForge, and the empirical Johnson-Mehl-Avrami-Kolmogorov equation was used to predict the passage of softening processes. Due to the absence of the coefficients of the Avrami equation, a series of experiments on physical modeling of the rolling-pressing technological process were conducted on an STD 812 torsion rheometer. The experiments were conducted at the temperature range of 250–450 ℃ and a strain rate of 1.0–20 s-1. By using physical modeling, it was proved that during processing on the RSM, it is necessary to develop a torsional deformation over the entire section of the workpiece, which leads to effective refinement of the structure. The derived formulas and simulation modeling of the obtained values of the stress-strain state (SSS) were used to simulate the technology of the combined process. Moreover, rational temperature-rate conditions were determined to deform the workpiece on the RSM. It was proved by mathematical modeling that shear deformations develop along the entire section of the workpiece during processing on the RSM, which leads to effective refinement of the structure and the formation of a fine-grained structure in the rods, i. e. products of the required quality are manufacture