| Parameter | Value | Advantage Description |
|---|---|---|
| Equipment Manufacturer | Wuxi Jingcheng | Well-known domestic manufacturer, reliable quality |
| Current Equipment Status | In operation | Still in normal production, good condition, not long-idle |
| Main Motor Power | 1250 kW × 1 | Ample power for cold rolling process |
| Main Motor Speed | 350/1000 rpm | Wide speed range, adapts to different rolling passes |
| Recoiler Motor Power | 900 kW × 1 | Strong recoiling capability, ensures good coil shape |
| Uncoiler Motor Power | 750 kW × 1 | Stable tension control, prevents strip slack |
| Recoiler/Uncoiler Speed | 400/1200 rpm | Wide speed range, adapts to coil diameter changes |
| Number of Mill Rolls | 4 | Simple structure, easy maintenance, low cost |
| Max Designed Width | 1050 mm | Wide rolling capability for medium-width strips |
| Actual Max Input Thickness | 4.0 mm | Strong material adaptability for thicker hot-rolled coils |
| Min Designed Finished Thickness | 0.02 mm | High-precision thin strip rolling capability |
| Actual Min Finished Thickness | 0.2 mm | Proven stable rolling thickness in actual production |
| Rolling Speed | 260 m/min | Moderate speed balancing efficiency and shape control |
| Max Rolling Force | 1500 tons | High rolling force for medium-strength materials |
| Working Roll Specification | Φ172 × 1150 mm | Reasonable diameter balancing stiffness and deflection |
| Backup Roll Specification | Φ1060 × 805 mm | Large diameter for high rigidity and load capacity |
| Screw-down Type | AGC | High-precision automatic thickness control |
| Mill Housing Window Size | 530 × 600 mm | Compact structure with good rigidity |
| Main Gearbox Model | 800# Tailong | Well-known brand, reliable transmission |
| Herringbone Gearbox | 1150# | High load capacity, smooth operation |
| Recoiler Gearbox Model | 630# Tailong | Matches recoiler motor, high transmission efficiency |
| Spare Parts | Extremely rich (see table) | Reduces future procurement costs, minimizes downtime |
| Spare Part | Quantity | Advantage Description |
|---|---|---|
| BUR Chocks | 4 sets (8 pcs) | Ample backup, reduces downtime from chock damage |
| BUR Heater | 1 set | Facilitates backup roll preheating or maintenance |
| Backup Rolls (BUR) | 4 pairs (2 new + 2 used) | New rolls ready for immediate use, used rolls as backup |
| Work Rolls (WR) | 93 pcs (6 new) | Extremely large inventory, years of operation without external purchase |
| Spare Bearings | 2 sets (new) | Critical rotating parts backup ensures continuous operation |
| Inner Sleeves & Outer Rings | 1 batch | Complete consumables for bearing maintenance |
Value: Manufacturer is Wuxi Jingcheng
Detailed advantages:
Wuxi Jingcheng is a well-known domestic manufacturer of metallurgical equipment with extensive experience in 4-Hi cold rolling mills and reversible mills.
Their equipment is known for reasonable structure, stable operation, and easy maintenance, with many successful installations in small-to-medium cold rolling enterprises in China.
Choosing this brand provides users with mature technology and ample after-sales service resources.
Value: Current status is In operation
Detailed advantages:
Electrical control system is fully functional
Mechanical drive system has no abnormal wear
Hydraulic and lubrication systems are in good condition
Condition of rolls, bearings, and other key components can be verified
Unlike long-idle used equipment, this mill is still in normal production, indicating all systems are functional with no major faults.
“In operation” status means:
Buyer can conduct on-site inspection before shutdown to observe actual operation, reducing procurement risk.
| Motor | Power | Speed | Advantage |
|---|---|---|---|
| Main Motor | 1250 kW | 350/1000 rpm | Sufficient power for 4.0mm → 0.2mm reduction |
| Recoiler Motor | 900 kW | 400/1200 rpm | High winding tension for tight, uniform coils |
| Uncoiler Motor | 750 kW | 400/1200 rpm | Stable back tension prevents strip slack and misalignment |
Detailed advantages:
Total installed power of 2900 kW is above average for this specification of 4-Hi mill.
Wide speed ranges (main: 350–1000 rpm, recoiler/uncoiler: 400–1200 rpm) allow adaptation to different pass speeds and tension requirements.
Recoiler motor power (900 kW) exceeds uncoiler motor power (750 kW), consistent with the physical requirement for higher tension on the recoiling side.
Value: Number of mill rolls = 4
Detailed advantages:
Lower maintenance cost: Simpler roll system, shorter roll change time, fewer spare part types.
Lower operator skill requirements: Shorter training period.
Lower capital investment: Significantly lower equipment price than 20-Hi mills.
Wide application range: Suitable for cold rolling of mild and medium-carbon steel in the 0.2–4.0 mm thickness range.
4-Hi mill consists of two work rolls + two backup rolls – a simple, clear structure.
Compared to 20-Hi mills, the 4-Hi mill offers:
Value: Max designed width 1050 mm, actual max width 1050 mm
Detailed advantages:
Home appliance panels (refrigerators, washing machines)
Construction thin sheets (pre-painted substrate)
Hardware stamping parts
Automotive interior structural parts
1050 mm width covers the vast majority of medium-width cold-rolled strip applications, such as:
Designed and actual values match, confirming stable performance at this width with no specification inflation.
Value: Actual max input thickness 4.0 mm
Detailed advantages:
4.0 mm input thickness means the mill can directly roll hot-rolled coils or pickled coils without an additional roughing mill.
Common hot-rolled input thicknesses range from 2.5 to 4.0 mm, which this mill fully covers.
Compared to mills limited to 2.5 mm input, this mill offers greater upstream material flexibility and wider sourcing options.
| Parameter | Designed Value | Actual Value | Explanation |
|---|---|---|---|
| Min Finished Thickness | 0.02 mm | 0.2 mm | Design极限极高，实际稳定生产厚度为 0.2 mm |
Detailed advantages:
Design minimum 0.02 mm: Demonstrates the mill’s mechanical precision and control system have the potential for ultra-thin rolling.
Actual minimum 0.2 mm: This is the stable production thickness achieved by the original owner, sufficient for the vast majority of cold-rolled sheet applications (home appliances, hardware, packaging, etc.).
The combination of 0.2 mm thickness and 1050 mm width represents the typical advantageous product range for this 4-Hi mill specification.
If thinner finished products (e.g., 0.1 mm) are required, they can be achieved through process parameter adjustments or control system upgrades.
Value: Rolling speed 260 m/min
Detailed advantages:
Easier shape control: Lower speed results in more uniform rolling force distribution, reducing shape defects (edge wave, center wave).
More stable thickness tolerances: AGC system responds more quickly at lower speeds, improving thickness control precision.
Less equipment wear: Bearings, rolls, gearboxes, and other components have longer service life at lower speeds.
Higher operational safety: Threading, coil unloading, and other operations are safer at lower speeds.
260 m/min is in the medium-speed cold rolling range. Compared to high-speed mills (600–800 m/min), it offers:
For 0.2–2.0 mm thick cold-rolled strips, 260 m/min is fully sufficient and delivers reasonable daily output.
Value: Maximum rolling force 1500 tons
Detailed advantages:
Can reduce 4.0 mm hot-rolled coils to 0.2 mm in 3–5 passes.
Can roll higher-strength materials (e.g., Q345, 510L low-alloy high-strength steel).
Allows higher reduction per pass, reducing total passes and improving production efficiency.
1500 tons (approx. 15,000 kN) is a larger-than-average configuration for a 1150mm 4-Hi mill.
Benefits of high rolling force:
Combined with large-diameter backup rolls (Φ1060 mm), the mill has high overall stiffness with uniform rolling force transmission.
| Roll Type | Specification (Dia. × Length) | Advantage |
|---|---|---|
| Working Roll | Φ172 × 1150 mm | Moderate diameter balances stiffness and contact stress |
| Backup Roll | Φ1060 × 805 mm | Large diameter provides high rigidity and load capacity |
Detailed advantages:
The large diameter (1060 mm) provides extremely high rigidity, effectively supporting the work rolls and reducing their elastic deflection.
Lower contact stress on large-diameter backup rolls results in longer roll surface life.
Compared to small-diameter work rolls (e.g., Φ60 mm), Φ172 mm work rolls offer better bending stiffness, suitable for medium-thickness strip rolling.
Larger work roll diameter means lower roll change frequency and lower roll consumption costs.
Working roll Φ172 mm:
Backup roll Φ1060 mm:
Value: Screw-down type is AGC (Automatic Gauge Control)
Detailed advantages:
AGC is the core technology of modern cold rolling mills, using real-time entry and exit thickness detection to automatically adjust rolling force or roll gap, ensuring finished thickness tolerances.
When combined with thickness gauges (X-ray or isotope), thickness tolerances can be controlled within ±0.005 mm.
The presence of AGC means this mill has high-precision rolling capability, meeting strict thickness requirements for home appliances, automotive, electronics, and other industries.
Value: Mill housing window size 530 × 600 mm
Detailed advantages:
Sufficient space for roll chocks
Good rigidity, reducing mill弹跳 (spring) during rolling
Convenient roll change operations
The mill housing is the most critical load-bearing component. Its window size determines overall mill rigidity.
The 530 mm × 600 mm window size is compact and reasonable for a 1150mm 4-Hi mill, ensuring:
