Longitudinal rolling or cross rolling without small deformation of the mandrel on the rolling tube on the longitudinal rolling or cross rolling sizing machine, the purpose is to make the rolling tube obtain the specified outer diameter size. The number of longitudinal rolling sizing machines is generally 5-12, mostly two-roller continuous rolling mills driven separately. The working frame is arranged at 45 degrees to the ground plane, and the adjacent frames are arranged at 90 degrees to each other. Increasing the number of sizing racks can expand product specifications and bring convenience to production. Cross-roll sizing is carried out on a two-roll or three-roll sizing machine, and it is generally arranged in a three-roll skew tube mill. Compared with longitudinal rolling and sizing, the diameter of the rolled pipe with cross-rolling and sizing is high in outer diameter precision and small in ellipticity. It is convenient to change specifications and varieties. No roll change is required, as long as the roller spacing is adjusted; the disadvantage is low productivity.
Hot-rolled thick-walled rolled pipes after leveling, in order to improve quality, expand variety standards and improve unit productivity, the thick-walled rolled pipes should be further deformed. To this end, two processing methods and three rolling mill methods that are fundamentally similar to the deformation principle are carried out, that is, rolling tube sizing and reducing processing methods. Correspondingly, there are sizing machines, reducing machines and tension reducing machines.
The intention of the sizing machine is to roll the rolled pipe after rounding into a round and finished product pipe with accurate dimensions, and the outer diameter of the rolled pipe is slightly reduced. The effect of the reducer is mainly to reduce the diameter, and the tension reducer can not only reduce the diameter, but also reduce the wall. A