1. Overview of Automatic Blooming Mill

An Automatic Blooming Mill is a critical piece of equipment in the steelmaking and rolling industry, primarily used for reducing large steel ingots or continuous cast blooms into smaller, more uniform billets or slabs for subsequent rolling processes.
It serves as the first-stage deformation equipment in a hot rolling line and determines the quality, dimensional accuracy, and internal structure of downstream steel products.

The “automatic” feature refers to the use of automation, hydraulic adjustment, and intelligent control systems to realize continuous, precise, and unmanned operation, which significantly improves production efficiency, product quality, and safety.

2. Working Principle

The working principle of an automatic blooming mill is based on metal plastic deformation under high temperature and compressive forces.
The ingot or bloom, heated to around 1,200°C, is fed between the rotating work rolls. Under rolling pressure, its cross-section decreases while the length increases, forming a smaller, elongated semi-finished product.

During this process, the automatic control system continuously monitors and adjusts key parameters such as:

• Rolling force and torque,

• Roll gap and speed synchronization,

• Metal temperature,

• Elongation ratio and shape accuracy.

Modern automatic blooming mills often use hydraulic screw-down devices, automatic roll gap control (AGC), and automation level 2 computer control systems to ensure uniform deformation and precise dimensions.

3. Structural Composition

A typical Automatic Blooming Mill is composed of the following key parts:

1. Mill Stand (Frame):
   Provides mechanical strength and rigidity to bear high rolling forces. Usually made of cast steel or welded steel structures.

2. Work Rolls and Backup Rolls:
   Main components that deform the metal. Rolls are made of forged alloy steel with high hardness and wear resistance.

3. Main Drive System:
   Includes AC/DC Motors, Gear Reducers, coupling shafts, and flywheels, responsible for torque transmission.

4. Hydraulic Screw-Down System:
   Adjusts roll gap precisely through hydraulic cylinders and pressure sensors.

5. Automation Control System:
   Employs PLC and computer control to manage speed, pressure, and product dimensions.

6. Roll Table and Manipulator System:
   Transports and positions the ingots or blooms before and after rolling.

7. Cooling and Lubrication System:
   Ensures stable temperature of rolls and prevents overheating.

8. Measuring and Feedback Devices:
   Include laser sensors, thermal imagers, and displacement detectors to monitor the rolling process.

4. Technical Features

1. Full Automation:
   Automatic feeding, rolling, and discharging reduce manual intervention.

2. High Rolling Force:
   Designed for heavy-duty deformation of large ingots or blooms.

3. Hydraulic Precision Control:
   Roll gap control accuracy can reach ±0.05 mm.

4. High Productivity:
   Continuous operation with short inter-pass time improves throughput.

5. Energy Efficiency:
   Equipped with regenerative drive systems and intelligent load management.

6. Stable Quality:
   Advanced control ensures consistent billet geometry and internal structure.

5. Types of Automatic Blooming Mills

According to structure and application, automatic blooming mills can be divided into:

1. Two-High Reversing Blooming Mill

• Simplest form, uses two rolls that rotate in both directions.

• Suitable for small and medium production scales.

2. Three-High Blooming Mill

• Features three rolls; rolling direction alternates between upper and lower rolls without reversing.

• Higher productivity, less idle time.

3. Four-High or Multi-Stand Blooming Mill

• Used for large-scale continuous rolling.

• Provides better rigidity, thinner final sections, and stable pressure distribution.

6. Application Fields

Automatic blooming mills are primarily used in:

• Steel plants producing billets, blooms, and slabs;

• Integrated steel rolling lines for bar, wire, and section steel;

• Special steel manufacturing, including tool steel and alloy steel;

• Seamless pipe and forging material production.

7. Maintenance and Operation

To ensure long-term stable operation, the following maintenance practices are recommended:

1. Regular inspection of roll wear and lubrication condition.

2. Monitoring of hydraulic system pressure and oil cleanliness.

3. Alignment check of rolls and mill stand.

4. Calibration of sensors and automation devices.

5. Periodic overhaul of drive and transmission components.

Conclusion

The Automatic Blooming Mill represents the modernization and intelligence of the steel rolling industry.
Its advanced control, high strength, and automation capabilities make it an essential part of any integrated steel plant.
With continuous technological innovation, it will play an even greater role in achieving high efficiency, high precision, and green manufacturing in the global steel industry.