Physical modeling of geometric and force parameters of the continuous longitudinal rolling of tubes without a mandrel

The process of continuous hot rolling is characterized by the presence of longitudinal forces that have a significant effect on the thickness of the pipe wall. It is very important to correctly determine the amount of reduction in the process of pipe deformation in order to obtain the wall thickness in the range specified by regulatory documents. The aim of the work was to obtain experimental data on the influence of the longitudinal force on the wall thickness of the pipe and compare them with the calculation results for one of the known dependencies. Conducted a physical simulation of the process of rolling tubes without mandrel. For the experiment, a scheme has been developed and technological equipment has been prepared, which made it possible to create conditions for the continuous rolling of a pipe with rear tension. The originality of the experiment was that it provided for the use of stepwise samples of the initial tube billet having cylindrical and conical sections. The cylindrical section provided the free passage of the workpiece through the deformation sleeve and a stable grip by the rolling rolls, while the conical section provided the creation of a rear longitudinal force during rolling. The magnitude of the rear tension was determined by calculation as the force of drawing the pipe. Shows the nature of the change in the thickness of the pipe wall with increasing magnitude of interstand tension. Based on the results of physical modeling, a conclusion was drawn on the appropriateness of using the well-known theoretical dependence for determining the wall thickness of a pipe during hot reduction of pipes with back tension applied. The results obtained are planned to be used to assess the force required to pull the pipe from the mandrel. This process is implemented on a TPA 159-426 extraction mill with a continuous rolling mill of Volzhsky Pipe Plant JSC.