The producing of Steel Strip by rolling
Steel strip is a type of sheet metal that is rolled from a semi-finished material, known as The Blank and is widely used in a variety of applications from automotive components to consumer appliances. Rolling will reduce and adjust the thickness and shape of the strip, increasing its strength and improving its surface finish. The most common rolling process for steel strip is cold rolling, which increases strength and hardness and improves surface finish, dimensional accuracy and shape.
To produce steel strip, several different processes can be used, but the traditional method is hot rolling. Starting from raw materials such as slabs, billets, or blooms, hot rolling is done at temperatures of more than 1,728°F (950° C). The hot-rolled material is then cooled and recrystallize at room temperature, then cut into a desired width and thickness. Hot-rolling may require a piece of the material to be re-annealed, which is the process of heating the material in order to soften the rolled steel.
Another type of rolling process used to manufactures steel strip is cold rolling. This process can also start with a slab, billet, bloom or cast strip, but the material is worked at much lower temperatures – typically in the range of 32°F to 842°F (0° C to 450° C). The material is then annealed and pickled in acid to make it more formable and provide a better surface for painting or coating. Cold rolling can produce strips of much higher strength and harder than hot rolled strips, and requires sophisticated equipment and expertise.
The cold rolling process is divided into different rolls:
1. Roughing Mills – These are used to reduce and prepare the material for cold rolling. The main components includes mill stands, Shear, Rollers, Pinch Roll and gearboxes.
2. Finishing Mill – Give the desired shape to the strip by milling it to the desired thickness. This is done using high-pressure rollers and a temper mill.
3. Tension Leveler – Leveler bends the strip to the desired shape. A strip is usually leveled at the end of its travel or at the entry point of the next pass.
4. Annealing Furnaces – The strip is heated up to a temperature that softens the material. The Furnace can heat up to temperatures up to 1700°F (750° C).
5. Inspection – The steel it is visually inspected in order to detect any flaws or irregularities.
The final step in the cold rolling process is coating. This can be done by galvanizing, paint/coating or lacquer to modify electrochemical or surface properties. This ensures that the strip is well protected against corrosion and other weathering elements.
Cold rolling of steel strip provides several advantages over other techniques, such as hot rolling. It is much faster and produces a much higher precision product with a much smoother surface. It also results in a much stronger and harder material that is much less susceptible to warping and corrosion. Cold rolling is also much more cost efficient than hot rolling and can create a much larger range of thicknesses, widths and shapes that can be used for a variety of different applications.
