Hot rolling ingots into tube with uniform wall thickness - where ingot is rotated before entering piercing mill

摘要

This is an addn. to 2505769, which described the mfr. of seamless metal tubes, where a red hot ingot is straightened, descaled by a high pressure spray, and fed into a rolling mill for piercing and stretching using a mandrel and several skew rolls. In the present invention, specifically prior to rolling, the ingot is rotated on its longitudinal axis at a peripheral speed corresp. to the magnitude and direction of the forces exerted by the rolls on the ingot. The pref. device consists of a long guide-cage which is rotated on its axis and contains rows of guide rolls arranged round the periphery of the ingot on axles which are at 90 degrees to the longitudinal axis of the cage, the guide-rolls being spring loaded in the radial direction. Ingots which are very long w.r.t. their dia. can be rolled to tubes with a uniform wall thickness, because the rotating guide cage prevents distortion of the ingot.