Preparation of rolled products for processing at a pipe rolling unit

Abstract

Purpose. The aim of this work is to examine rolling processes with variable deformation modes by transferring part of this deformation from the mill under consideration to the preceding mill, as well as to develop a process for preparing the billet ends by transverse planetary burnishing with idle rolls. Methodology. Using the slip-line method, the forces acting on the idle rolls during transverse planetary burnishing of the billet end, as well as the torque and power of the burnishing process, were determined. The thinning of the wall at the front end of the billet during its preparation by transverse planetary burnishing with idle rolls was analytically established. Findings. One of the main reserves for further increasing productivity, saving metal, and improving geometric dimensions in the production of hot-rolled seamless pipes is the use of variable deformation modes across the wall thickness. Examples of additional operations carried out on various pipe-rolling mills are considered, demonstrating their high efficiency. For the design of a method for preparing the front ends of billets, planetary rolling processes applied in pipe-rolling production were analyzed. Originality. The method of transferring part of the deformation from the main mill to the preceding mill has been further developed, which significantly improves rolling conditions in the main mill and enhances its performance indicators. Practical value. The process of transverse planetary burnishing of billet ends appears highly promising and warrants further research and development. The results of this work can be applied in selecting the most rational method of metal preparation for rolling, taking into account the specific technology of a given pipe-rolling mill.