Exclusion of the pipe rear end defects in the process of the PRP 220 rolling using the FE modeling

Abstract

A line for the production of hot-deformed pipes on a pipe-rolling plant 220 equipped with an automatic elongation mill is considered. In the maintenance the appearance of longitudinal end defects typical for thin-walled pipes was revealed. On the basis of a software package implemented with the use of FEM, a model of the deformation zone of a two-stage process of the lengthwise rolling of pipes on a short mandrel has been simulated. Analysis of the flow of the hollow bloom metal in this process makes it possible to establish the nature of the defect formation, as well as to calculate its influence on the power parameters of the process. The formation of a defect at the rear ends of the pipe is associated with the loss of stability of the hollow bloom section when the hollow bloom metal flows into the roll caliber outlets, which leads to an increase in the contact surface of the rolls with the workpiece and the mandrel with the workpiece, as well as to contact with the surfaces of the rolls that are not intended for direct interaction with heated metal. As a result, a technical solution has been proposed that allows restricting the loss of stability of the rear end of the pipe and eliminating a decrease in the loads on the working tool of the rolling stand, due to the degeneration of the rear end defects of the pipes. This solution is justified using FE modeling. © 2021 Author(s).