Capillary rolling is the main deformation process of hot-rolled seamless steel pipe production, its role is to make the capillary wall thickness of the pipe wall thickness near or at the finished product, and the elimination of longitudinal wall thickness of the capillary produced during piercing and uneven, the other can improve shortage of surface quality of the inner and outer tube, the outer diameter of the control blank pipe and roundness. Hollow shell rolled into a tube close to the finished size of the shortage.

1, The automatic rolling machine: automatic rolling machine for the two-roll irreversible type vertical mill, which is characterized by a pair of high-speed reverse rotation roll back feed roller in the work rolls, the role is to go through a rolling capillary to the foreground a second rolling, and therefore its low productivity, most domestic unit has been transformed or eliminated. Roll material is infinitely more chilled cast iron, ductile iron or chilled ductile iron, hardness HSD50 above.

2, Two rollers rolling units: Rolling Mill is a more advanced steel mill, which is perforated after hair long sleeves on the mandrel, and through multi-rack sequential arrangement adjacent rack roller seam mutual mistake 90 ° the continuous rolling machine rolling.
Rolling roll material mostly nickel-chromium-molybdenum unlimited Chilled ductile iron (also known as pearlite ductile iron), nickel-molybdenum unlimited Chilled ductile iron (also called nodular cast iron needles), female part hardness HSD50-65. Foreign design first frame rolling roll and some use of forged steel or graphite materials to further enhance the strength of the vehicles roll.

3, Three-roll rolling units: adjustable three-roll MPM tube machine (PQF) Italy INNSE companies overcome the inherent limitations of the two-roll MPM and developed, since it 360 ° aperture type is divided into three parts, reducing the gap between the linear velocity of each roll groove bottom edge, and thus high precision steel rolling.

4, Assel pipe mill: Assel tube rolling three-roll rolling, which consists of three driving rolls and a mandrel consisting of a closed loop line pass.
ROLL identity inlet cone, shoulder rolls, flat area and four outlet cone, materials used 4Cr5MoSiV1 forged steel, semi-steel or alloy cast ductile iron, heat treatment hardness: forged steel rolls controlled HSD65-75, semi-steel roll control in HSD50 -60, iron alloy roll control in HSD55-65 (this kind of material rolls imported unit design, examples of successful application in the country less).