Method and appts. for pierce rolling seamless steel pipes

摘要

The method concerns pierce rolling of seamless pipes, according to which a plug mandrel is located along the axis (X-X) of a rotating and advancing billet between two conical main rolls and two disk rolls. The disk rolls (3u, 3d) are inclined to the axis (X-X) at an angle ( delta ) satisfying the following two conditions: eta 2 + 2 deg < delta < 9 deg (1) delta + eta 1 < 12 deg (2). eta 1 = the inlet cone angle of the main rolls and eta 2 = the outlet cone angle of the main rolls. Also claimed is an appts. for implementation of the proposed method. The appts. is novel in that it has two conical main rolls (1A, 1B) and two disk rolls (3u, 3d) arranged alternately around the blank axis (X-X). The disk rolls are inclined to the axis (X-X) at an angle within a specified range of values dependent on the geometry of the main rolls.