Features of the stress-strain state of screw piercing of extra-thick-walled hollow billets for mechanical engineering

Abstract

Based on the previously developed model of the process of screw piercing of a particularly thick-walled workpiece, an analysis of its stressed and deformed state for feed angles of 6 and 12 degrees was carried out. The analysis of stress intensity parameters (SI) in twolongitudinal sections, as well as the parameters of strain rate intensity (SDI) and finite strain intensity (FSI) in cross sections was carried out. The SI distribution pattern in the longitudinal sections is very heterogeneous, the maximum stresses are observed at the mandrel toe and in the pinch region. The analysis of SDI showed its more correct distribution with maximum values in the nip, and also made it possible to identify the displacement of zones with the highest SDI value towards the point of contact between the workpiece and work rolls. The formation of an annular zone with low FSI values was revealed when analyzing the deformed state of the workpiece at higher feed angles, and a greater uniformity of the FSI field values at smaller angles, which can be used in the future to study the metal structure of the workpiece wall.