AGC 850 mm Skin Pass

Basic Equipment Parameter Table

3. Detailed Equipment Description

(1) Overall Functional Positioning & Applicable Processing Scenarios

1. The AGC 850mm skin pass mill is an indispensable core finishing unit installed at the rear of cold rolling lines, continuous annealing lines and hot-dip galvanizing lines. It is specially designed for skin pass processing of annealed low-carbon steel strips, galvanized steel strips and stainless steel strips. Annealed metal strips carry an obvious yield plateau inside the material, which tends to generate orange peel textures and stretch indentations during subsequent stamping and forming processes. Through light-reduction rolling conducted by this skin pass mill, yield point elongation can be fully removed. Meanwhile, the machine rectifies strip flatness, improves surface gloss and stabilizes dimensional tolerance, which greatly raises the finished product yield of downstream stamping parts, sheet metal components, home appliance casings and hardware accessories.
2. This machine is a heavy-duty industrial complete metallurgical equipment manufactured by Wuxi Wuye in 2008, and it was shut down and stored in 2020. All main mill housings, roll assemblies, transmission mechanisms, hydraulic AGC pressure control systems and Siemens electrical control cabinets are fully intact without missing core functional parts. All supporting rolls, drive motors, hydraulic valve manifolds and operation consoles are original factory matched components. The whole equipment has undergone comprehensive disassembly and overhaul, hydraulic pipeline cleaning, motor insulation performance testing and electrical control program debugging. All roll surfaces with wear marks have been repaired and calibrated to recover standard processing performance. After connecting power supply, hydraulic station and cooling circulation system on site, the entire line can operate synchronously for mass continuous production, which saves the long production, delivery and on-site commissioning cycle required for brand-new customized rolling mills.
3. The mill supports metal coils with a maximum width within 850mm, and can be perfectly matched with cold rolling mills, continuous annealing furnaces and hot-dip galvanizing production lines. It serves as an irreplaceable key piece of equipment for steel finishing processes, and is widely applied to mass production in steel processing plants, galvanizing factories and stainless steel deep-processing manufacturers.

(2) Roll System & Main Mill Mechanical Structure Configuration

1. The rolling mill adopts a mature 4-high skin pass structural layout, composed of two core roll assemblies: work rolls and backup rolls, matched with front and rear S roll tension conveying units. The work roll specification is Ø280×900 mm, which directly contacts the surface of steel strips to complete light-pressure skin pass, and its roll body length covers the maximum processing width of 850mm. The backup rolls with dimension Ø580×850 mm own larger diameter and superior structural rigidity, fitting closely to the back of work rolls to share rolling pressure. This design effectively prevents bending deformation of work rolls under load, guarantees uniform transverse thickness across the whole strip width and avoids wave edges caused by uneven rolling force.
2. Three groups of independent large-diameter S rolls with 800mm diameter are arranged at the uncoiler inlet, the middle section of the rolling zone and the recoiler outlet respectively. Relying on the large contact area between rolls and steel strips, S rolls precisely regulate the overall line tension of strips, effectively preventing thin strips from stretching, slipping and lateral deviation during conveying. They steadily feed metal strips into the rolling zone, and maintain stable material running status at the maximum speed of 240 m/min, so as to avoid serious production accidents such as strip breakage and steel piling during high-speed rolling.
3. The main mill housing is integrally cast with heavy cast steel, with thick wall thickness and strong impact resistance against periodic rolling pressure, so it will not produce permanent deformation under long-term high-pressure skin pass working conditions. Inside the housing, there are built-in AGC hydraulic down-pressure cylinders, high-precision thickness detection sensors and strip flatness adjustment mechanisms, which can dynamically adjust rolling pressure in real time to realize fully automatic closed-loop thickness control. The complete set of heavy-duty hydraulic swing arms and uncoiler/recoiler reel mechanisms are equipped along the line, which automatically finish steel coil loading, unloading and tension lifting operations to cut down manual auxiliary labor.

(3) Power System Configuration of Six Independent High-Power Drive Motors

1. 284kw Main Mill Motor: It provides core rolling torque for skin pass procedures, matching high-speed processing working conditions. It can stably support the limit operating speed of 240 m/min, and delivers sufficient large torque to ensure uniform light reduction on thin strips without slipping or speed fluctuation.
2. 225kw Uncoiler Drive Motor: It undertakes constant-speed unwinding of raw steel coils and supplies stable unwinding tension. It adapts to heavy-weight annealed coils and galvanized coils, and avoids strip wrinkling, loosening and surface scratch during unwinding.
3. Three Groups of S Roll Motors (67kw, 80kw, 119kw): They control the rotating speed of inlet, middle and outlet S rolls separately, and adjust tension gradient of the whole line by sections. This design solves the problem of tension difference between the head and tail of thin steel strips, and prevents strip stretching deformation and uneven thickness.
4. 166kw High-Power Recoiler Motor: It completes winding of finished strips after skin pass, with a wide adjustable tension range. When multi-layer strips are wound together, it can tighten coils evenly, ensuring neat end faces and compact coil shape of finished products, which facilitates subsequent slitting and cross-cutting processing.

(4) Advantages of Siemens AGC Automatic Thickness Electrical Control System

1. The complete electrical control system adopts original Siemens hardware, including main control PLC, digital speed regulating devices, AGC closed-loop thickness control modules, human-machine operation console and a full set of low-voltage electrical cabinets. The system integrates high-precision thickness detection sensors, which collect real-time transverse and longitudinal thickness data of steel strips, feed signals back to hydraulic down-pressure cylinders and dynamically adjust rolling pressure to realize fully automatic AGC thickness control. Manual adjustment of reduction is no longer required, and the control precision of thickness tolerance is outstanding.
2. The independent split operation console is equipped with physical buttons, adjusting knobs, fault indicator lights and display panels. Operators can check real-time operating parameters including line speed, tension value, rolling pressure, strip thickness and motor running status. The human-machine interaction interface is intuitive and easy to operate, so workers can quickly finish speed setting, tension matching, thickness compensation, equipment start-stop and fault reset after simple training.
3. The electrical control system is programmed with complete interlock protection logic, covering strip breakage protection, tension overload protection, motor overheating protection, hydraulic overpressure protection and emergency stop interlock. In case of abnormal conditions during high-speed production, the system will automatically reduce speed or shut down the whole line to avoid major production accidents such as steel piling, strip breakage and equipment damage, and improve overall operation safety of the production line.

(5) Core Production & Processing Advantages

1. Ultra-high production efficiency: The designed maximum skin pass speed reaches 240 meters per minute, far higher than conventional low-speed skin pass mills with speed ranging from 100 to 180 m/min. It fits continuous high-volume mass production of annealing and galvanizing lines, greatly lifting the tonnage of coils processed per hour and cutting down unit energy consumption and labor costs.
2. AGC fully automatic closed-loop thickness control: Different from simple skin pass mills with manual reduction adjustment, this machine is equipped with mature AGC automatic gauge control system. It revises rolling pressure in real time, minimizes longitudinal thickness fluctuation of the whole coil, ensures consistent dimensional standard of finished strips and stable processing size in subsequent stamping procedures.
3. Complete segmented tension control: Three independent S rolls matched with corresponding drive motors realize separate tension regulation for inlet, rolling zone and outlet. For ultra-thin and super-soft annealed steel strips, tension can be precisely controlled to eliminate defects such as stretching thinning, surface wrinkling and lateral deviation, delivering finished strips with smooth surface without scratches.
4. Complete integrated matching of full-process equipment: The whole line covers uncoiling, S roll tension conveying, 4-high skin pass main mill and finished recoiling with all supporting facilities intact. All roll systems, drive motors, hydraulic systems and electrical control systems are complete without missing parts. After overhaul on site, it can be directly connected to front-end annealing and galvanizing production lines, with no extra auxiliary machines required, lowering overall investment cost for manufacturers.

(6) Overall Machine Structure, Auxiliary Parts & Operation Maintenance Features

1. The heavy-duty main frame of the equipment has passed aging treatment, so it will not deform under long-term high-pressure rolling conditions. The whole line is equipped with a complete hydraulic station, cooling and lubrication circulation system, roll supporting mechanisms and safety guardrails. All hydraulic pipelines and cable lines are arranged in standardized classification, with dust-proof and oil-proof design to extend the service life of electrical and hydraulic components.
2. The full set of roll systems (work rolls, backup rolls, S rolls) are original factory matched, with roll surfaces treated by wear-resistant hardening process and controllable wear degree. Supporting tooling for roll surface repair and replacement is delivered together with the machine. The six drive motors are intact with good insulation performance, free of oil leakage and bearing damage. Only regular lubrication maintenance is required in later operation, leading to low daily maintenance cost.
3. Standardized Siemens electrical control system features high versatility of spare parts, and related accessories are widely available in the market. If electrical components wear out in later operation, replacement parts can be purchased and installed quickly without the trouble of discontinued and hard-to-source spare parts. The whole machine adopts modular structural design; rolls, motors and hydraulic valve manifolds can be disassembled and overhauled separately, bringing convenient maintenance and short downtime without interfering with continuous production plans of processing factories.