750 20HI Cold Rolling Mill

I. Equipment Overview & Project Background

1.1 Basic Equipment Information

This equipment is a 20-Hi 750mm reversible cold rolling mill, manufactured in 2012. The mill was originally serving a domestic stainless steel precision strip processing enterprise, and has been used for many years in the cold rolling of stainless steel coils. Its products are widely applied in medical devices, food machinery, chemical equipment, architectural decoration, electronic components, and other fields. The equipment was officially taken offline in June 2026, with excellent overall integrity and fully functional electrical control systems, capable of quickly resuming production.

1.2 Current Equipment Status

• Complete machine with no major damage to main mechanical structures;

• Electrical control system in good condition with no missing modules;

• Spare parts included (specific list to be further confirmed);

• The seller can provide disassembly, refurbishment, installation, and commissioning full-process technical services.

1.3 Equipment Positioning

The 20-high rolling mill, with its high roll system rigidity, concentrated rolling force, and high thickness control precision, is recognized as the mainstay equipment in the cold rolling of stainless steel, silicon steel, and precision alloy strips. This equipment is specially designed for precision stainless steel strip, accommodating both wide-width and thin-gauge production capabilities, making it a rare high-precision, fully-configured model in the used equipment market.

II. Detailed Core Technical Parameters

III. Equipment Structure Composition

This 20-Hi cold rolling mill mainly consists of the following subsystems:

3.1 Mill Main Frame System

• Integrated housing-type stand: Manufactured from high-strength cast/forged steel with excellent rigidity and deformation resistance, providing a stable foundation for precision rolling.

• 20-roll system:

• 2 work rolls (diameter Ф40–50mm), directly contacting the strip to achieve rolling deformation;

• 2 first intermediate rolls (Ф76×800mm), transmitting rolling force and assisting drive;

• 4 second intermediate rolls (Ф132×730mm), further distributing rolling force;

• 12 back-up bearing rolls, providing rigid support to ensure overall roll system stability.

• Roll arrangement: Tower-type arrangement, enabling rolling force to be progressively transmitted from the work rolls to the rigid back-up roll system, forming a high-rigidity rolling window.

3.2 Main Drive System

• Main motor: Z4-560-3 DC motor, 900kW power, adopting DC speed regulation system for wide-range stepless speed adjustment, meeting rolling speed requirements for different passes.

• Reducer and gear stand: High transmission efficiency, smooth operation, low noise.

3.3 Coiling and Uncoiling System

• Left/right coilers: Each equipped with one Z4-225-31 DC motor, independently driven, achieving constant tension control to ensure strip does not deviate or get scratched during coiling/uncoiling.

• Solid drum: Simple structure, easy maintenance, suitable for stainless steel strip coiling with good coil quality.

3.4 AGC Automatic Gauge Control System

• Hydraulic screw-down mechanism: Fast response speed, control accuracy within ±0.002mm.

• Thickness gauge feedback closed-loop control: Real-time strip thickness monitoring via X-ray or laser thickness gauge, automatically adjusting screw-down position to ensure consistent finished product thickness.

• Compensation functions: Equipped with advanced control algorithms including roll gap compensation, oil film thickness compensation, and temperature compensation.

3.5 Auxiliary Systems

• Process lubrication and cooling system: Using emulsion or rolling oil circulating cooling to remove rolling heat, lubricate the roll gap, and extend roll life.

• High-pressure descaling/cleaning system: Ensuring strip surface cleanliness.

• Hydraulic station and pneumatic system: Providing power sources for screw-down, tension, and auxiliary actions.

• Electrical control cabinets and operator stations: PLC control system with user-friendly HMI for parameter setting, operation monitoring, and fault alarming.

IV. Core Advantages Analysis

4.1 Precision Advantage — Outstanding Thin-Gauge Production Capability

The greatest advantage of a 20-high rolling mill over 4-high or 6-high mills lies in its extremely high roll system rigidity. This equipment has work rolls with a diameter of only Ф40–50mm, which, under the same rolling force, can achieve greater unit contact stress, making it easier for the metal to undergo plastic deformation, thereby rolling thinner products. This equipment can achieve a minimum finished thickness of 0.05mm, which has been verified in actual production, meeting the stringent requirements of the precision strip market.

Furthermore, the AGC automatic gauge control system achieves closed-loop automatic thickness adjustment, eliminating human error from manual operation. During high-speed rolling, the AGC can adjust the screw-down position in real-time based on thickness gauge signals, ensuring that thickness deviation along the entire strip length is controlled within an extremely small range. For precision stainless steel strips, thickness tolerance is typically required to be ≤±0.003mm, and this equipment fully possesses the capability to meet this requirement.

4.2 Width Advantage — Covering Mainstream Stainless Steel Strip Specifications

The maximum rolling width of 650mm covers the core specification range of the stainless steel strip market. Currently, the mainstream width range for precision stainless steel strips is 400–650mm, and this equipment sits at the upper end of this range, offering wide applicability and flexible response to different width order requirements. Whether for wide thin strips for medical devices or narrow precision strips for electronic components, this equipment is fully capable.

4.3 Configuration Advantage — Complete with No Missing Parts

Compared to many used equipment offerings in the market that are "incomplete," the greatest advantage of this equipment is its complete and full configuration:

• Main motor and coiler/uncoiler motors are all original matching DC motors with unified brand and good compatibility;

• All 20 rolls are complete, with an intact roll system;

• Electrical control system is in good condition, with PLC cabinets, operator stations, thickness gauges, and hydraulic servo systems all present;

• Spare parts are included, further reducing subsequent maintenance costs.

For used equipment buyers, the "completeness" of the equipment directly relates to the production resumption cycle and additional investment amount. The high completeness of this equipment means that buyers can enter the refurbishment and commissioning phase immediately after purchase, without spending significant time and money searching for missing components, greatly shortening the time from procurement to production.

4.4 Speed Advantage — Balancing Efficiency and Quality

The rolling speed of 300–450 m/min falls within a reasonable range for comparable 20-high rolling mills. This speed ensures both high production efficiency (short single-pass rolling time, high shift output) and prevents negative effects such as reduced lubrication cooling effectiveness, loss of strip shape control, or surface quality deterioration caused by excessive speed. Within this speed range, the process lubrication system can fully perform its cooling and lubricating functions, ensuring smooth strip surface and good flatness.

4.5 Screw-down System Advantage — AGC Replacing Traditional Electric Screw-down

Traditional 20-high rolling mills mostly adopt electric screw-down with worm gear adjustment, which has disadvantages such as slow response, low precision, and low automation. This equipment uses an AGC hydraulic screw-down system, offering the following significant advantages:

• Fast response speed: Hydraulic system responds in milliseconds, far faster than electric screw-down;

• High control precision: Can achieve micron-level thickness control;

• High automation: Can be integrated with thickness gauges and tension control systems for fully automatic rolling;

• Compensation functions: Can automatically compensate for roll gap thermal expansion, oil film changes, etc.

4.6 Coiling Method Advantage — Solid Drum Reliability and Durability

This equipment adopts a solid drum design, which offers the following advantages over collapsible drums:

• Simple structure: No complex expansion/contraction mechanisms, resulting in low failure rate;

• Easy maintenance: Low daily maintenance workload, simple spare parts replacement;

• Stable coiling quality: Good drum rigidity, uniform strip tension during coiling, minimal risk of telescopic coils or loose coils;

• Long service life: High strength of solid structure, wear-resistant, not easily deformed under long-term use.

4.7 Cost Advantage — High Cost-Performance Investment Choice

A brand-new domestic 20-Hi 750mm cold rolling mill currently costs approximately RMB 15–25 million (including electrical control and auxiliary systems). As used equipment, this mill is priced at only 30%–50% of a new machine (specific price to be negotiated with the seller), yet its core performance indicators (rolling precision, speed, width) are essentially comparable to new equipment. For enterprises with limited budgets but seeking high-quality rolling capabilities, this equipment is an extremely attractive alternative solution.

In addition, with a 2012 manufacturing year, the equipment is in its "prime" stage among metallurgical equipment (the design life of metallurgical equipment is typically 20–30 years), with ample remaining service life, a short payback period, and significant economic benefits.

V. Conclusion

This 20-Hi 750mm 20-High Cold Rolling Mill, manufactured in 2012, features complete equipment configuration, excellent process performance indicators, and a reliable service background. Its core parameters — 650mm rolling width, 0.05mm minimum thickness, AGC automatic gauge control, 250 tons rolling force, and 450m/min rolling speed — give it strong competitiveness in the used cold rolling equipment market.

With the turnkey technical services provided by the seller — including disassembly, refurbishment, installation, and commissioning — this equipment enables buyers to quickly establish precision stainless steel strip production capabilities at a far lower investment cost than new equipment, making it a high-return, high-quality choice.