THE METHOD OF DECREASING THICKNESS OF TUBE WALL AND ROLLING MILL FOR DECREASING THICKNESS OF TUBE WALL

摘要

1. The method for reducing tube wall thickness in combined processes of tube rolling and internal broaching, whereby in the wall thickness reduction area pressure is exerted on the internal tube surface to increase internal diameter, and pressure is exerted on the external tube surface to guarantee constancy of external diameter in accordance with patent nr 139009, consisting in that unevenly distributed axial stress, with values proportionate to the difference between local elongation of the tube and average elongation throughout the section concerned, is applied to the tube cross-section at the point of its exit from rollers.2. The mill for reducing tube wall thickness, containing a drawing plug, whose one end is fitted to the body, and on the other end having an extending head, surrounded by rollers, whose axes and surfaces are parallel to the tube axis and which are through sliding radial bearing placed in a rotating head and supported with a stop ring connected with the driving mechanism, and apart from that it is equipped with a pusher according to patent nr 139009, consisting in that the cylindrical part (6) of the head (5) extends beyond the rolling area (2) up to the place where the external guide (9) is situated, the external guide (9) not sliding radially in relation to the rolling axis, and the cylindrical part (6) of the head (5) makes up an entity with part (8) or is a separate element fastened in that part.IMAGE