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Cold drawn (rolled) seamless steel pipe: round tube billet → heating → piercing → heading → annealing → pickling → oiling (copper plating) → multi-pass cold drawing (cold rolling) → billet tube → heat treatment → straightening → Hydraulic test (flaw detection) → mark → warehousing.

    What is a cold drawn quilted tube? Hot-rolled steel pipes use continuous casting slabs or blooming slabs as raw materials, which are heated by a walking heating furnace, and then enter the roughing mill after high-pressure water descaling. The rough-rolled materials are cut head, tail, and then enter the finishing mill for computer control After rolling, after the final rolling, it is cooled by laminar flow and coiled by a coiler to become a straight hair coil. The head and tail of straight hair curlers are often tongue-shaped and fish-tail-shaped, with poor thickness and width accuracy, and the edges often have defects such as wave shape, hemming, and tower shape.

    The coil weight is heavier and the inner diameter of the steel coil is 760mm. (Generally used in the pipe making industry.) After the straight hair coil is processed by the head, tail, trim and multi-pass straightening, leveling and other finishing lines, then it is cut or recoiled to become: hot rolling Steel plates, flat hot-rolled steel coils, slitting strips and other products. If the hot-rolled finished coil is pickled to remove the oxide scale and coated with oil, it becomes a hot-rolled pickled coil. This product has a tendency to partially replace cold-rolled plates, and the price of seamless steel pipes is moderate, which is very popular among users.

     Cold-drawn steel pipes use hot-rolled steel coils as raw materials. After pickling to remove the oxide scale, they are cold-rolled. The finished products are hard-rolled coils. The cold-work hardening caused by continuous cold deformation increases the strength, hardness and toughness of the hard-rolled coils. The plastic index drops, so the stamping performance will deteriorate, and it can only be used for simple deformed parts. Hard-rolled coils can be used as raw materials for hot-dip galvanizing plants because all hot-dip galvanizing units are equipped with annealing lines. The weight of the rolled hard coil is generally 6 to 13.5 tons, and the inner diameter of the steel coil is 610mm.

    Generally, cold continuous rolled plates and coils should undergo continuous annealing (CAPL unit) or bell furnace annealing to eliminate cold work hardening and rolling stress, and meet the mechanical performance indicators specified by the corresponding standards.
    The surface quality, appearance, and dimensional accuracy of cold-rolled steel sheets are better than those of hot-rolled steel sheets, and the thickness of their products is as thin as about 0.18mm, so they are favored by users. The cold-rolled steel coil is used as the base plate for deep processing of the product, which becomes a high value-added product.

    Such as electro-galvanized, hot-dip galvanized, fingerprint-resistant electro-galvanized, color-coated steel coil and vibration-damping composite steel plate, PVC composite steel plate, etc., which make these products have excellent qualities such as beautiful appearance and high corrosion resistance, and have been widely used. The cold-rolled steel coil must be finished after annealing, including cutting head, tail, trimming, leveling, leveling, recoiling, or longitudinal shearing. Cold rolled products are widely used in industries such as automobile manufacturing, household appliances, instrument switches, construction, and office furniture. The weight of each bale after the steel plate is bundled is 3 to 5 tons. The flat sub-roll weight is generally 3~10 tons/roll. The inner diameter of the coil is 610mm.