A rolling mill has a common construction independent of the specific type of rolling being performed:
· Work rolls
· Backup rolls - are intended to provide rigid support required by the working rolls to prevent bending under the rolling load
· Rolling balance system - to ensure that the upper work and back up rolls are maintained in proper position relative to lower rolls
· Roll changing devices - use of an overhead crane and a unit designed to attach to the neck of the roll to be removed from or inserted into the mill.
· Mill protection devices - to ensure that forces applied to the backup roll chocks are not of such a magnitude to fracture the roll necks or damage the mill housing
· Roll cooling and lubrication systems
· Pinions - gears to divide power between the two spindles, rotating them at the same speed but in different directions
· Gearing - to establish desired rolling speed
· Drive motors - rolling narrow foil product to thousands of horsepower
· Electrical controls - constant and variable voltages applied to the motors
· Coilers and uncoilers - to unroll and roll up coils of metal
Slabs are the feed material for hot strip mills or plate mills and blooms are rolled to billets in a billet mill or large sections in a structural mill. The output from a strip mill is coiled and, subsequently, used as the feed for a cold rolling mill or used directly by fabricators. Billets, for re-rolling, are subsequently rolled in either a merchant, bar or rod mill. Merchant or bar mills produce a variety of shaped products such as angles, channels, beams, rounds (long or coiled) and hexagons.