4-Hi 700mm Cold Rolling Mill

1. Equipment Overview
This is a 4-Hi 700mm four-high reversible cold rolling mill, manufactured by Wuxi Jinjiein2012 and taken offline on September 5, 2026. This is a professional-grade small-to-medium specification cold rolling mill, specifically designed for high-precision cold rolling of stainless steel and mild steel strips. The 4-Hi configuration consists of 2 small-diameter work rolls and 2 large-diameter backup rolls—a classic setup for cold-rolled strip that balances rolling precision, shape control capability, and equipment rigidity.

2. Manufacturer Background
Wuxi Jinjie is a well-known enterprise in China's metallurgical equipment manufacturing sector, with extensive engineering experience in the R&D and production of cold rolling mills, reversible mills, temper mills, and related equipment. The Jinjie brand enjoys high market recognition in the cold rolling processing industry, with products known for high precision, stable operation, and convenient maintenance. This equipment, manufactured in 2012, represents Jinjie's design and manufacturing level for small-to-medium specification cold rolling mills of that period.

3. Core Highlights — Equipment Age and Condition
This equipment was manufactured in 2012andtaken offline on September 5, 2026, with approximately 14 years of actual service. In cold rolling equipment, 14 years represents the mature phase of the equipment lifecycle—main structures (housings, roll bearing chocks, gearboxes, etc.) have been verified through long-term operation and are in relatively stable condition. The equipment was just shut down in September 2026, not long-idle, allowing buyers to understand its actual operating condition before shutdown and conduct necessary on-site inspections before dismantling. For small-to-medium specification cold rolling equipment, this age and condition offer good procurement value.

4. Main Motor System — Dual Motor Drive
The mill is equipped with 2 main motors, each rated at 450kW, for a combined total of 900kW. Dual motor drive is the standard configuration for reversible mills—during the reversing rolling process, the strip passes through the mill in multiple passes, with the coiler and uncoiler swapping roles after each pass, requiring two independent drive systems to control the coiling/uncoiling operations on both sides. The symmetrical configuration of 2 x 450kW motors ensures balanced power delivery in both rolling directions, with 900kW total power being a reasonable configuration for 700mm width and 3.0mm entry thickness rolling of stainless steel and mild steel, meeting the precision rolling requirements of small-to-medium specification strips.

5. Recoiler and Uncoiler Systems
The recoiler and uncoiler are equipped with 2 x 500kW motors. The recoiler/uncoiler motor power (500kW) exceeds the single main motor power (450kW), reflecting the relatively high tension control requirements of this cold rolling mill—recoiling tension directly affects the tightness of finished coils, strip surface quality, and inter-pass rolling stability. The 500kW recoiler/uncoiler motors ensure stable recoiler operation under high-speed rolling and high-tension conditions, reducing issues such as coil loosening and interlayer slippage, suitable for precision coiling of stainless steel and mild steel strips.

6. Mill Type — 4-Hi Four-High Mill
This equipment is a 4-Hi (four-high) cold rolling mill, consisting of 2 small-diameter work rolls and 2 large-diameter backup rolls. The 4-Hi configuration is the mainstream choice for cold-rolled strip:

• Work rolls: Directly contact the strip and provide rolling deformation; smaller diameters help reduce rolling force and achieve thinner gauges;

• Backup rolls: Provide rigid support to the work rolls, reducing work roll bending deflection under immense rolling forces, ensuring shape precision and thickness consistency.

7. Roll Systems

• Work Roll: Specification Φ160×730mm—roll diameter 160mm, barrel length 730mm. The small-diameter work rolls help reduce rolling force, enable thin-gauge rolling, and ensure strip surface quality;

• Backup Roll: Specification Φ520×650mm—the large-diameter backup rolls provide robust support to the work rolls, reducing work roll bending deflection, ensuring shape precision and thickness consistency;

• Screw-down System: Adopts AGC (Automatic Gauge Control) hydraulic screw-down—featuring fast response and high control precision, capable of real-time roll gap detection and adjustment during high-speed rolling, ensuring finished strip thickness tolerances are controlled within a small range across the entire length.

8. Designed Rolling Parameters

• Designed rolling materials:SS (Stainless Steel) and MS (Mild Steel) —the equipment is suitable for cold rolling of both stainless steel and mild steel strips, offering broad material adaptability;

• Maximum designed input thickness (entry):3.0mm;

• Minimum designed finished thickness (exit):0.15mm—rolling from 3.0mm to 0.15mm represents a total reduction of 95%, demonstrating the good cumulative deformation capability of the 4-Hi mill;

• Maximum designed rolling width:660mm—with work roll barrel length of 730mm, the effective rolling width of 660mm leaves sufficient margin;

• Actual maximum rolling width used by the original owner:660mm—consistent with design, equipment capability verified;

• Actual maximum input thickness used by the original owner:3.0mm—consistent with design;

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

• Maximum rolling speed:200m/min;

• Maximum rolling force:900 tons (approximately 9000kN).

9. Maximum Rolling Force — 900 Tons of Guarantee
The 900-ton (approximately 9000kN) maximum rolling force provides ample deformation capability. For 700mm width and 3.0mm entry thickness cold rolling of stainless steel and mild steel, the 900-ton rolling force configuration is reasonable and sufficient. Stainless steel has high deformation resistance, requiring sufficient rolling force for effective thickness reduction; mild steel, while having lower deformation resistance, also requires stable rolling force output during multi-pass cumulative deformation. The 900-ton maximum rolling force ensures the equipment maintains stable thickness accuracy and shape quality when rolling thicker materials and higher-strength grades.

10. AGC Hydraulic Screw-Down System
This mill employs an AGC (Automatic Gauge Control) hydraulic screw-down system, rather than traditional electric screw-down. AGC hydraulic screw-down offers the following significant advantages:

• Fast response: Completes roll gap adjustment in milliseconds, adapting to thickness fluctuations during high-speed rolling;

• High control precision: Enables micron-level roll gap adjustment, ensuring finished strip thickness tolerances are controlled within extremely tight limits across the entire length;

• Strong dynamic adjustment capability: Real-time compensation under conditions such as entry thickness fluctuations, speed changes, and tension fluctuations, ensuring stable exit thickness;

• Improved product quality: AGC is a core configuration of modern cold rolling mills, directly determining product thickness accuracy and quality stability.

11. Electrical Control System — Eurotherm 590
The mill's electrical control system is supplied by Eurotherm, model 590. Eurotherm is a globally renowned provider of industrial automation and process control solutions, with deep expertise in metallurgical rolling drive control. The Eurotherm 590 series DC drive is known for its stability, reliability, high control precision, and strong anti-interference capability, widely used in cold rolling mills, reversible mills, and other metallurgical equipment. According to the technical data sheet, the electrical control system is in good condition (Yes) with no missing components—meaning the mill's automation control system, drive control system, AGC, PLC, sensors, and associated equipment are all complete and functional, requiring no additional investment from the buyer for electrical system repair or replacement.

12. Applicable Materials and Downstream Applications
This equipment can roll stainless steel (SS) and mild steel (MS) strips, with finished thickness ranging from 0.15mm to 3.0mm (exit) and maximum width of 660mm. The strips rolled by this equipment are widely used in:

• Stainless steel products: Kitchenware, tableware, sinks, bathroom hardware, etc.;

• Stainless steel decorative strip: Architectural decoration, elevator panels, curtain walls, etc.;

• Electronics and electrical: Battery connector strips, shielding covers, precision electronic components, etc.;

• Automotive components: Decorative trims, clamps, sealing frames, etc.;

• Tube manufacturing: Stainless steel precision welded pipe and decorative tube raw material;

• Hardware stamping: Various stainless steel and mild steel stamped parts;

• Cold-rolled commercial coils: Sold directly as commercial coils to downstream processors.

13. Equipment Status and Services
The technical data sheet clearly records:

• Equipment taken offline on September 5, 2026, with on-site inspection available before dismantling;

• Electrical control system intact (Eurotherm 590), no missing components;

• Spare parts list available upon request (Yes, details to be confirmed);

• Disassembly services available (Yes);

• Equipment refurbishment and maintenance services available (Yes).