Digital Control of Electrically Welded Pipe Manufacturing Technology in a Tesa 20–102 Mill

Abstract

In order to manufacture hot-reduced pipe from welded pipe billets in a continuous stretch-reducing mill (SRM) 20–102 coiled hot-rolled product is used of normal precision with respect to thickness, specified in GOST 19903. The actual value of longitudinal difference in thickness for the main mass of coiled rolled product comprises 70% of the proportion of pipe tolerance with respect to thickness, which makes it difficult to satisfy the specifications of GOST 10704 and GOST 3262 for pipe wall thickness, and also increases the metal consumption factor for a ton of finished product. Due to development of a rapid algorithm and a calculation program for reduction production regimes, rational calibration of rolls, pipe stretching between mills and stands in a 22-stand SRM, a control system for hot-reduced pipe manufacturing technology is created and introduced. As a result of this the longitudinal difference in pipe wall thickness compared with the longitudinal difference in strip wall thickness is reduced by an order of magnitude. This makes it possible to manufacture pipe in the minus range of permissible values for deviation of wall thickness, to reduce the metal consumption factor, to increase the output of finished product, to reduce specific energy expended in pipe rolling in the SRM, and to assimilate manufacture of a thin-walled range of pipes.