6-Hi 1200mm cold rolling mill

1. Equipment Overview
This is a 6-Hi 1200mm six-high reversible cold rolling mill, manufactured by Antai in 2012 and still in normal operation. This is a large-scale wide-width high-speed cold rolling mill, specifically designed for high-precision, high-speed cold rolling of mild steel (MS) strips. The 6-Hi configuration represents an advanced design for modern wide-width cold rolling mills—compared to 4-Hi mills, 6-Hi mills incorporate intermediate rolls to achieve superior shape control capability and a wider thickness application range.

2. Manufacturer Background
Antai is a significant enterprise in China's metallurgical equipment manufacturing sector, with deep technical expertise in the R&D and production of large-scale cold rolling mills, 6-Hi mills, temper mills, and other high-precision cold rolling equipment. The Antai brand enjoys high market recognition in the cold rolling industry, with products known for large-scale design, high speed, and high precision.

3. Core Highlight — Equipment Still in Operation
The most notable highlight of this equipment is that it is still in normal operation (Still running) and has not been shut down. This means:

• The equipment is continuously operating on the production line, with all functional components in good working condition;

• Buyers can arrange on-site trial runs with actual materials before dismantling, directly verifying core performance indicators such as rolling precision, thickness tolerance, shape quality, and speed stability;

• No"idling diseases"such as rust, seal aging, or lubricant dry-out caused by long-term idling;

• The equipment's operating history and maintenance records are complete and traceable, with exceptionally high equipment condition transparency;

• This is the most ideal condition for second-hand equipment—buyers can see the equipment's performance under real working conditions with their own eyes.

4. Main Motor System — Dual Motor Ultra-High-Power Drive
The mill is equipped with 2 main motors, model Z710-630, each rated at 1600kW, with a speed range of 0-422/1000 r/min, for a combined total of 3200kW. This represents the highest single-motor power and highest total power among all equipment introduced so far. Dual motor drive is the standard configuration for reversible mills—the symmetrical configuration of 2 x 1600kW ultra-high-power motors ensures ample power reserve and stable speed control under high-speed rolling (900m/min) and high-rolling-force (8000kN) conditions.

5. Recoiler and Uncoiler Systems

• Uncoiler motor: Power rating 316kW, responsible for smooth pay-off of the mother coil;

• Recoiler motor: Power rating 618kW, responsible for recoiling finished coils in reversible rolling operations;

• Each with 2 units, forming a front-rear symmetrical configuration;

• Coiling method adopts a collapsible drum, which retracts during coil unloading for easy removal of finished coils, improving unloading efficiency and operational safety.

6. Mill Type — Advanced 6-Hi Configuration
This equipment is a 6-Hi (six-high) cold rolling mill, consisting of 2 work rolls, 2 intermediate rolls, and 2 backup rolls. The 6-Hi configuration offers the following significant advantages over 4-Hi mills:

• Superior shape control: Intermediate rolls can perform axial shifting, effectively compensating for roll bending deformation caused by rolling force, achieving more precise shape control;

• Thinner finished gauges: Smaller work roll diameters, supported by intermediate rolls, enable rolling of thinner gauges (minimum 0.15mm);

• Higher rolling speeds: Better roll system stability, suitable for high-speed rolling (maximum 900m/min);

• Wider thickness application range: Capable of handling a broad range of specifications from thick to thin on the same equipment.

7. Roll Systems

• Work Roll: Specification Φ220/Φ190×1200mm—new roll diameter 220mm, replaced when worn to 190mm, barrel length 1200mm. Small-diameter work rolls help reduce rolling force and enable thin-gauge rolling;

• Intermediate Roll: Specification Φ350/Φ320×1150mm—new roll diameter 350mm, replaced when worn to 320mm, barrel length 1150mm. Intermediate rolls can perform axial shifting and are the key actuators for shape control;

• Backup Roll: Specification Φ950/Φ890×1100mm—new roll diameter 950mm, replaced when worn to 890mm, barrel length 1100mm. Ultra-large-diameter backup rolls provide robust rigid support to the work rolls and intermediate rolls, ensuring minimal roll system deformation under high rolling forces.

8. Designed Rolling Parameters

• Designed rolling material: MS (Mild Steel) , equivalent to Q195, Q235 and other plain carbon structural steels—the most widely used cold-rolled strip material;

• Maximum designed input thickness (entry): 3.5mm;

• Minimum designed finished thickness (exit): 0.15mm—rolling from 3.5mm to 0.15mm represents a total reduction of 95.7%, demonstrating the powerful thin-gauge rolling capability of the 6-Hi mill;

• Maximum designed rolling width: 1050mm—with work roll barrel length of 1200mm, the effective rolling width of 1050mm leaves sufficient margin;

• Actual maximum rolling width used by the original owner: 1050mm—consistent with design;

• Actual maximum input thickness used by the original owner: 3.5mm—consistent with design;

• Actual minimum finished thickness used by the original owner: 0.15mm—consistent with design;

• Maximum rolling speed: 900m/min—the highest rolling speed among all equipment introduced so far, reflecting the equipment's high-speed rolling capability;

• Maximum rolling force: 8000kN (approximately 800 metric tons of force).

9. Maximum Rolling Speed — 900m/min High-Speed Advantage
The 900m/min maximum rolling speed is one of the most outstanding performance indicators of this equipment. In cold-rolled strip production, rolling speed directly determines shift output and production efficiency. The 900m/min high-speed capability意味着:

• Extremely high production efficiency: Shift output far exceeds low-speed mills (such as the 980mm mill's 250m/min), suitable for high-volume continuous production;

• Superior thickness accuracy: High-speed rolling combined with AGC automatic thickness control enables more stable thickness tolerance control;

• Excellent surface quality: High-speed rolling contributes to obtaining smoother strip surfaces;

• 900m/min represents a medium-to-high-speed configuration for 1200mm-class 6-Hi reversible cold rolling mills, reflecting high-level design and manufacturing capability.

10. Maximum Rolling Force — 8000kN of Power
The 8000kN (approximately 800 tons of force) maximum rolling force provides ample deformation capability. Although mild steel has lower deformation resistance than stainless steel, the large cumulative reduction between 3.5mm entry and 0.15mm exit (95.7%) requires substantial rolling force, and high-speed rolling conditions require sufficient rolling force to ensure thickness accuracy and shape quality. The 8000kN rolling force configuration fully meets these demanding requirements.

11. Electrical Control System — Siemens Brand Guarantee
The mill's electrical control system is supplied by Siemens, a globally leading brand in industrial automation and drive control, with world-class technology in high-speed cold rolling control. Siemens electrical control systems are known for stability, reliability, high control precision, fast dynamic response, and strong anti-interference capability. According to the technical data sheet, the electrical control system is in good condition (Yes) with no missing components. For a 900m/min high-speed mill, the performance of the electrical control system is critical—the Siemens system ensures precise coordination of speed control, tension control, and thickness control.