China High Precision HI Reversing Cold Rolling Mill Suppliers | Quality Steel Rolling Factory Equipment
The Theory of Four Roll Rolling Mill
⚙️ The four roll rolling mill system is composed of two support rolls and two working rolls, forming a precision pressure processing assembly.
During milling, through pressing cylinder or mechanical pressing device, the pressing force will transmit to support roll bearing stand, support roll, working roll, and finally act on the rolled piece. The work piece height will be reduced (become thinner), length extended (become longer), then to meet the expected specifications.
Due to the impact of pressing force, rollers will become bending, the workpiece edges will become thinner. Rollers need grinding its convexity according to practical situation.
Product Introduction
The four-high reversing cold rolling mill is an important metal pressure processing equipment, widely used in metallurgy, mechanical manufacturing, non-ferrous metal processing and other industries. It performs cold rolling on metal materials through the coordinated action of four rolls, achieving material thinning, surface quality improvement and mechanical property enhancement.
🔩 Key Structure: Work rolls directly contact the rolled piece to perform rolling deformation, while backup rolls support the work rolls to reduce their deflection and ensure stability and accuracy of the rolling process.
The reversible design enables the rolling mill to roll in both forward and reverse directions without frequent adjustments to the position of the rolled piece or the rolling mill, significantly improving production efficiency.
- 1 Application Scenarios: Mainly used for rolling various metal strips and plates — stainless steel, carbon steel, alloy steel, copper, and aluminum — meeting strict industry requirements for thickness, width, surface quality, and mechanical properties.
- 2 Automotive Manufacturing: Rolled plates are used for body panels, requiring high strength, good formability, and corrosion resistance.
- 3 Electronic & Electrical Industry: Rolled strips are used to manufacture precision components, requiring high surface finish and dimensional accuracy.
- 4 Industry Standards: Design, manufacture, and acceptance follow strict standards covering structure, performance, safety, and environmental protection, ensuring reliable and safe operation.
- 5 Operation & Maintenance: Operators require professional training; regular maintenance including roll replacement, lubrication system inspection, and electrical system maintenance is essential for long-term stable operation.
Technical Parameter Table
| MILL MODEL / TECHNICAL PARAMETER | 650 | 750 | 850 |
|---|---|---|---|
| Material | Carbon steel and low alloy steel | Carbon steel and low alloy steel | Carbon steel and low alloy steel |
| Material thickness (mm) | 2.0 ~ 3.0 | 2.0 ~ 3.0 | 2.0 ~ 3.5 |
| Material width (mm) | 400 ~ 550 | 500 ~ 650 | 600 ~ 750 |
| Finish thickness (mm) | 0.5 ~ 0.15 | 0.5 ~ 0.16 | 0.5 ~ 0.18 |
| Pressing force (KN) | 5000 | 6000 | 7500 |
| Support roll Specification (mm) | Φ550×600 | ¢650×700 | ¢700×820 |
| Middle roll Specification (mm) | ———— | ———— | Φ300/Φ280×820 |
| Working roll Specification (mm) | Φ185/Φ165×650 | ¢205/Φ190×750 | Φ225/Φ205×850 |
| Driving method | Working roll driving | Working roll driving | Working roll driving |
| Main motor | DC motor | DC motor | DC motor |
| Speed reducer | Joint gear box | Joint gear box | Joint gear box |
| Uncoiler (specifications) | ¢610×650 | ¢610×750 | ¢610×850 |
| Recoiler (specifications) | ¢508×650 | ¢508×750 | ¢508×850 |
| Rolling speed (m/min) | 360 | 450 | 540 |
| Uncoiler tension (KN) | 30 | 35 | 45 |
| Recoiler tension (KN) | 10 ~ 70 | 10 ~ 80 | 10 ~ 90 |
| Pressing method | Hydraulic AGC | Hydraulic AGC | Hydraulic AGC |
| DC speed regulator | Siemens 6RA70 | Siemens 6RA70 | Siemens 6RA70 |
| Electric control | Siemens PLC | Siemens PLC | Siemens PLC |
📌 Remark: The model and parameters shown in this table are for reference only. The design and production can be tailor-made according to user's requirements.
Frequently Asked Questions (FAQ)
Q
What is a four-high reversing cold rolling mill and how does it work?
A four-high reversing cold rolling mill consists of four rolls: two working rolls that directly contact the metal strip to apply rolling pressure, and two backup rolls that support the working rolls to prevent excessive deflection. The "reversing" feature allows the mill to roll material in both forward and reverse directions without repositioning the strip, enabling multiple passes for progressive thickness reduction until the desired final thickness is achieved.
Q
What materials can be processed by the four-high reversing cold rolling mill?
The four-high reversing cold rolling mill is designed to process a wide range of metal materials, including carbon steel, low alloy steel, stainless steel, alloy steel, copper, and aluminum. It is suitable for producing strips and plates used across industries such as automotive manufacturing, electronics, electrical appliances, and mechanical engineering.
Q
What are the available mill models and what thickness ranges can they achieve?
Three standard mill models are available — 650, 750, and 850 — with input material thickness ranging from 2.0–3.5 mm. The finished thickness can be reduced to as thin as 0.15–0.18 mm depending on the model. The 850 model supports the widest material width (600–750 mm) and the highest pressing force (7,500 KN), making it suitable for heavier production demands.
Q
What control and drive systems are used in these rolling mills?
All three mill models are equipped with DC motors for the main drive, a joint gear box as the speed reducer, and Hydraulic AGC (Automatic Gauge Control) as the pressing method. Precision speed control is provided by the Siemens 6RA70 DC speed regulator, and the entire system is managed by a Siemens PLC electric control system, ensuring accurate and stable process control.
Q
Why do rollers require convexity grinding and how does it affect product quality?
During rolling, the significant pressing force causes the working rolls to bend slightly, which results in the edges of the workpiece becoming thinner than the center. To compensate for this deflection and ensure uniform thickness across the strip width, the rollers are precision ground with a specific convexity profile. Regular convexity grinding is essential to maintain consistent product quality and dimensional accuracy.
Q
Can the rolling mill specifications be customized to meet specific production requirements?
Yes. While the standard models (650, 750, 850) cover a broad range of applications, the design and production of the four-high reversing cold rolling mill can be fully tailor-made according to individual customer requirements. Parameters such as roll dimensions, rolling speed, pressing force, tension range, and control system configurations can all be customized to match specific material types, production volumes, and quality standards.