Skew-rolling mill for elongation of seamless hollow blank heated to forming temperature

摘要

The skew-rolling mill for elongation of a seamless hollow blank includes at least two rolls which rotate in the same direction, are provided with conical entry and exit sections, and are set at a transport angle relative to the rolling axis. It further includes a mandrel bar attached to a holding bar. Between the entry section and the working section of the roll forming the smallest roll gap there is a shoulder with a concave curvature and, after a point of inflexion, a section with a convex curvature. The latter section has either a single radius of curvature or two radii of curvature, with the first being smaller than the second. Both these radii are larger than the radius of the concave section. The mill is characterised by the fact that the concave section (10) with a radius (R1) is preceded by a straight section (13) which tangentially goes over into the concave section, and is provided with a transition radius for merging with the entry section (7).