A review of pipes reduction methods aimed at end longitudinal different-walled decreasing

Abstract

Formation of incrassate pipes end is one of main drawbacks of pipes reducing with tensioning method. Therefore, the matter of perfection of reducing mills designs, rollers passes, rolling regimes aimed at end shearing decreasing is very actual. A review of steel pipes hot rolling methods at multi-stand reduction-tensioning mills was carried out, aimed at elaborating of measures for decreasing of end longitudinal different-walled. Techniques of pipe end parts rolling considered, including control of rotary speed regimes of adjacent stands rollers; changing of distance between stands; increasing of pipe end parts temperature to facilitate their tapering; increasing inter-stands tension at the expense of magnetic field application. Also such techniques were considered as application of a short fixed mount in the first mill stand; use of endless reducing; use of idler stands, making breaking down effect and increase of tension. Analysis results of the patent search with utilization of internet-resources showed, that a method of tension increasing at the expense of rollers rotation speed control at pipe end parts rolling is the most acceptable method of pipes incrassate ends length and end shearing decreasing. An actuality of further studies of the elaboration of modified reducing mills speed regimes was noted, aimed at pipes incrassate ends length decreasing depending on their geometry, steels grades, assortment of produced pipes and other technological factors.