Selecting the appropriate rolling mill requires comprehensive consideration of process requirements, equipment parameters, and production goals. The following are the key steps and precautions:
1. Selection of process layout scheme
Half continuous rolling scheme
Suitable for small and medium-scale production, usually consisting of one two-roll reversible rolling mill (with functions of flipping and pusher) and 6 to 8 continuous rolling mills. If the raw material is rectangular billet, a vertical/flat layout can be adopted to reduce the flipping process.
Continuous rolling scheme
Suitable for large-scale continuous production, divided into rough rolling units (4 to 6 rolls), intermediate rolling units (2 groups), finishing rolling units, and reduction and sizing units. A priority is given to using 4 rough rolling units to improve flexibility.
2. Selection of billet and matching of rolling mill
Steel type adaptability
High carbon steel, alloy mold steel, etc. require using forged or rolled billets to improve the internal structure;
Carbon structural steel, spring steel, etc. can use continuous casting billets to reduce costs.
Compression ratio control
Choose the billet specification based on the minimum compression ratio of the steel type and the maximum cross-section of the product to avoid central porosity or surface defects. Bearing steel is preferably rectangular billets to reduce porosity, but the die design needs to be optimized.
3. Configuration of rolling mill parameters
Extension coefficient and rolling passes
The average extension coefficient of high alloy steel should be ≤ 1.26, and that of carbon steel-like materials should be controlled within 1.28 to 1.29;
The extension coefficient of finishing passes should not be too large, to facilitate size adjustment.
Rolling mill specification selection
Prioritize selecting a few models to reduce spare parts inventory. The length of the rolls needs to take into account both rigidity and processing range. The rough rolling units need to reserve the bite margin, and the finishing rolling units need to ensure dimensional accuracy.
4. Auxiliary systems and maintenance
Lubrication and cooling
Regularly check the oil circuit and cooling water system to avoid poor lubrication or temperature fluctuations affecting the rolling quality.
Safety protection
Before operation, it is necessary to confirm that the rolls are centered, the guide and deflector devices are clean, and emergency stop buttons and protective equipment are equipped to avoid steel pile-up or strip-through accidents.
5. Automation and commissioning Modern rolling mills need to be integrated with computer control systems (such as the HM interface), where parameters are optimized through simulation testing, and the gap and tension control are regularly calibrated.
