1. Overview of the Steel Blooming Mill

A Steel Blooming Mill is a key type of hot rolling equipment used in the primary stage of steel processing.
Its main purpose is to convert large cast ingots or continuous casting slabs into semi-finished blooms or billets, which are then sent to subsequent Rolling Mills such as bar mills, section mills, or plate mills for further processing.

The blooming mill is considered the “first step of deformation” in the hot rolling line. It plays a decisive role in determining the internal quality, grain structure, and dimensional accuracy of steel products.

Typically, a blooming mill operates under high temperature and high load conditions, requiring massive rolling forces, high torque drives, and strong structural rigidity.

2. Working Principle of the Steel Blooming Mill

The basic principle of the blooming mill is hot plastic deformation.
When a steel ingot, heated to about 1150–1250°C, passes between two or three rotating rolls, it undergoes progressive compression and elongation.

The deformation is repeated several times in longitudinal and transverse directions, gradually reducing the section size and improving metal homogeneity.

Each rolling pass changes the cross-section and improves density, surface quality, and internal structure, making the bloom suitable for downstream processing.

3. Structural Composition of a Steel Blooming Mill

A modern blooming mill typically includes the following main components:

1. Main Stand (Rolling Frame):
   The heavy steel frame that supports the rolls and bearings.

2. Work Rolls:
   Large-diameter rolls used to deform the metal.

3. Roll Adjustment System:
   Hydraulic or mechanical screw-down devices to control roll gap and reduction.

4. Drive System:
   High-power Electric Motors, couplings, gearboxes, and spindles for torque transmission.

5. Manipulation Equipment:
   Includes pusher devices, roller tables, tilters, and transfer mechanisms for ingot movement.

6. Cooling and Lubrication System:
   Ensures roll temperature stability and minimizes wear.

7. Automation and Control System:
   PLC, sensors, and control software manage rolling parameters like speed, temperature, and pressure.

4. Types of Steel Blooming Mills

Blooming mills can be classified in several ways:

(1) By Number of Rolls

• Two-high reversing mill:
  Most common type; rolls rotate alternately for forward and backward passes.

• Three-high mill:
  Allows continuous rolling without reversing the ingot, improving productivity.

(2) By Production Method

• Ingot Blooming Mill:
  Designed for rolling steel ingots into blooms.

• Continuous Casting Blooming Mill:
  Used after the continuous casting process to improve structure and surface quality.

(3) By Degree of Automation

• Semi-automatic mills – rely partly on manual control.

• Fully automatic mills – computer-controlled with precise adjustment of roll gaps and speeds.

5. Technical Characteristics and Advantages

1. High Rolling Force and Torque:
   Designed to handle heavy deformation of large ingots.

2. Excellent Metal Quality:
   Promotes uniform structure and removes casting defects like shrinkage cavities and porosity.

3. Wide Application Range:
   Suitable for carbon steel, alloy steel, stainless steel, and tool steel.

4. Strong Structural Design:
   Ensures stability during high-load operation.

5. Automation and Precision Control:
   Modern mills integrate sensors and computers for accurate deformation control.

6. Efficient Material Utilization:
   Reduces waste and improves yield.

6. Application Fields

Steel blooming mills are widely used in:

• Integrated Steel Plants — as the first step in hot rolling lines.

• Alloy Steel and Tool Steel Production — to refine structure before precision rolling.

• Railway and Shipbuilding Industry — for heavy section blooms and billets.

• Forging Plants — for preforming ingots into intermediate shapes.

7. Operation and Maintenance

To ensure reliable performance and longevity:

• Maintain proper lubrication of bearings and gearboxes.

• Regularly inspect rolls for cracks or wear.

• Control ingot temperature to prevent uneven deformation.

• Monitor hydraulic system pressure and oil temperature.

• Schedule regular maintenance and calibration of sensors.

Conclusion

The Steel Blooming Mill serves as the foundation of modern steel rolling production.
By transforming raw steel ingots into uniform semi-finished products, it ensures the quality, efficiency, and consistency of subsequent rolling processes.

With continuous progress in automation, digitalization, and intelligent manufacturing, the blooming mill continues to evolve toward higher precision, energy efficiency, and sustainability, playing a vital role in the advancement of the global steel industry.