Novel technique for producing large-sized seamless steel pipe

Abstract

The invention discloses a new production process of a large seamless steel pipe. The process comprises the following steps: pipe billets are preheated to the temperature of 1050-1290 DEG C by a heating furnace, and delivered to a three-roll skew rolling piercing mill for piercing by a skew roll table conveying mechanism to finish diameter expansion and wall reduction rolling, the maximal ratio of diameter to wall D / S is over 32, and hollow billets are produced; the hollow billets are delivered to a three-roll skew rolling elongating finishing mill by a shift oblique orbit conveying mechanism to finish diameter expansion and wall reduction rolling or diameter reduction and wall reduction rolling, and the pierced billets are rolled, straightened, cropped end, cut to length, defect are detected, and the finished products are obtained after passing inspections. The new production process also perfects and improves the conventional three-roll skew rolling seamless steel pipe process, solves the problems of not rolling thin walls and great extension in the three-roll skew rolling process, the diameter expansion and wall reduction rolling can be carried out, and the diameter reduction and wall reduction rolling can be carried out. The new production process is especially suitable for rolling large and oversized seamless steel pipes (Phi is 500-2000mm), the ratio of single reduced diameter and expanded diameter is more than 30%, the reduced wall diameter is more than 70%, and the reduced wall thickness is 5-7 times of that of a longitudinal pipe rolling mill.

Description

Technical field [0001] The invention relates to a seamless pipe rolling production process in the field of metal pressure processing. technical background [0002] The current seamless steel pipe production process is: after the round tube billet is heated by the heating furnace, it is pierced and rolled into a thick-walled hollow tube through one or two piercings, and then rolled into a waste tube with a cross-rolling extension machine or a continuous rolling mill. After sizing, correcting, suppressing, testing, and painting, the finished product is made and shipped out. [0003] Most of the current piercing processes use two-roll cross-rolling piercing and three-roll cross-rolling piercing. The two-roll cross-rolling piercing technology is becoming more and more perfect and has been widely used. [0004] Three-roll cross-rolling piercing was first proposed by the Mannesman brothers when they were studying cross-rolling. In 1465, the first three-roll cross-rolling piercing machi...

AI Technical Summary

Problems solved by technology

[0013] The purpose of the present invention is to provide a new production method for large seamless steel pipes in view of the shortcomings or problems existing in the existing production of seamless steel pipes, which can not only carry out diameter-reducing and wall-reducing rolling, but also can carry out diameter-reducing and wall-reducing rolling , especially suitable for rolling large and extra large seamless steel pipes

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