Cold-rolled steel sheet and strip are widely used across industries, and their production methods can be categorized into single-sheet rolling and coil rolling, depending on how the steel is processed.
Single-Sheet Rolling
Originally carried out with two-high mills, modern single-sheet rolling now primarily uses four-high cold rolling mills. These are divided into reversible and non-reversible types based on rolling direction.
►Non-Reversible Four-High Mill:
Steel plates-typically of grades like Q195, Q235, or ST12-are manually fed into the rolling mill one by one. After completing one pass, the entire batch is moved by crane for the next pass, repeating the process until the final required thickness is achieved.
►Reversible Four-High Mill:
Two common operating methods are:
①Each sheet (e.g., SPCC, DC01) is rolled back and forth until it reaches its final thickness before the next sheet begins. This method minimizes surface defects and is ideal for large-size plates.
②All sheets are processed for the first pass and then returned one by one for the second pass. Though this increases productivity, there is a slightly higher risk of surface scratching.
Single-sheet rolling doesn't involve tension, so each pass usually has a reduction rate under 14%. As the number of passes increases, so does the degree of work hardening-limiting this method's ability to produce ultra-thin cold-rolled products.
Coil Rolling
Now the dominant production method, coil rolling is divided into single-stand coil rolling and multi-stand continuous rolling, using a variety of mill types-two-high, four-high, six-high (Sendzimir), twelve-high, and twenty-high-available in both reversible and non-reversible configurations.
►Single-Stand Non-Reversible Mills:
These mills (often two- or four-high) are used for rolling narrow strip steel coils with widths under 600 mm. Common grades include SPCC, A1008, and DC01, with rolling speeds between 1.2 and 2.0 m/s. Roll body lengths range from 100 to 600 mm, and diameters from 100 to 300 mm.
►Multi-Stand Continuous Cold Rolling Mills:
Compared to single-stand mills, this configuration offers significant advantages:
①High Rolling Speeds - typically 25 m/s or more (up to 41 m/s).
②Excellent Product Quality, meeting diverse requirements for mechanical strength, surface condition, thickness, and dimensional tolerance.
③Greater Metal Yield, due to effective rolling of both coil ends, reducing trimming losses.
④High Output, with annual capacity ranging from several hundred thousand to over one million tons.
⑤Advanced Control Systems, including hydraulic reduction and automation technologies that improve efficiency and consistency.
This method supports the efficient, large-scale production of cold-rolled steel for applications in automotive manufacturing, home appliances, precision stamping, and industrial machinery. Frequently rolled grades include SPCC, DC01, Q195, Q235, ST12, and A1008.
