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Introduction To Cold Rolling And Hot Rolling
Jun 06, 2018

The concept of cold rolling and hot rolling

1. Hot rolled

With continuous casting slab or slab as raw material, by step heating furnace, high pressure water and phosphorus into the roughing mill, after roughing expected by the cutting head, tail, and then into the finishing mill, and the implementation of computer control rolling and finishing after after laminar cooling (computer controlled cooling rate) and the winder, and became a straight hair volume. The head and tail of the straight hair coil are usually in the shape of tongue and fishtail, with poor accuracy in thickness and width. The coil weight is heavy and the inner diameter of steel coil is 760mm. The general pipe industry likes it. To pass through the cutting head and cutting tail straight hair volume, trimming and straightening, level off of multichannel time after finishing line processing, cutting board or heavy volume, again become namely: hot rolled steel plate, flat hot-rolled coil, slitting and belt and other products. Hot - rolled finishing roll if the oxide skin is removed by pickling and coated with oil will become hot - rolled pickling plate roll.

2. The cold rolling

With hot rolled steel coils as raw material, after acid pickling to remove oxide skin for cold rolling, the finished product is hard, because of cold work hardening caused by deformation of continuous cold rolling hard roll strength, increase hardness, toughness and plastic index fell, the stamping performance deterioration, can only be used for simple deformation of the parts. The rolled coil can be used as raw material for hot galvanizing factory, because the hot galvanizing unit is equipped with annealing line. The rolled coil weight is generally 6~13.5 tons, and the inner diameter of the steel coil is 610mm. Generally, cold continuous rolling plates and rolls should be deannealed by continuous annealing (CAPL unit) or cover furnace to eliminate cold hardening and rolling stress and achieve the mechanical performance indexes specified in the standard. The surface quality, appearance and dimension precision of cold rolled steel plate are better than hot rolled steel plate.