Process flow for Khopoli Steel Plant

(Introduction to HR Slitter , Pickling & CR MILL

Process flow chart

HR SlitterHR SLITTINGSlitting serves three purposes :

• HR coils are available in widths which are wider than the required for Cold Rolling. The trimming / slitting is done with the HR Slitter.

• The HR coils available may have width variation of the order of up to 20 mm, so to get the uniform width these coils are slitted.

• The edges of HR coils may get damaged during transportation because of poor packaging and/or improper handling. In order to remove these damaged edges the HR coils are trimmed /slitted.

Process flow Hot roll Slitter

Slitting Process• Slitting is a process of cutting larger width coils into narrower

width coils with repetitive accuracy at a high speed.• The process begins with the fitting of large steel coils onto an

uncoiler drum whereby it is uncoiled and fed through a leveller to be flattened. Subsequently, the sheets are fed through a slitter to slit the sheets into strips of specific width.

• After slitting, the strips are relayed through tension pads or synchrony-wind rolls to provide tension prior to the recoiling process. The tensed strips are then recoiled using a recoiler to form slitted coils.

Pickling

• Pickling is a metal surface treatment used to remove impurities, such as stains, inorganic contaminants, rust or scale from ferrous metals, copper, precious metals and aluminium alloys using HCL acid.

Process flow Pickling Line

Cold Roll Milling6 Hi Mill – 2 No's4 Hi Mill – 3 No'sWidth Range – 250 – 1300 mm

The primary function of Cold Rolling is to reduce the thickness of Hot Rolled Pickled strip at room temperature. During the operation overall max reduction of up to 90 % in thickness of the HR Coil can be achieved. Cold rolling occurs with the metal below its recrystallization temperature (usually at room temperature), which increases the strength via strain hardening up to 20%. It also improves the surface finish and holds tighter tolerances.

Schematic Diagram 6 High Rolling Mills

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