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4 Roll Plate Rolling Machine Operation Manual

Four-Roller Plate Rolling Machine is one curved, calibration equipment, which specialized in sheet metal bending work and can roll a variety of specifications of cylindrical, and curved workpieces.

The sheet metal can be shaped and flattened on the 4-roll bending machine. In addition, appropriately adjusting the relative position between the side roll and the top roll, by repeatedly rolling bending, minimum cylinder diameter up to the diameter of the top roll can be gotten.

3 roll bending machine
4 roll bending machine

4-roll bending machines are with a wide range of needs and functions in the petroleum, chemical, shipbuilding, and machinery manufacturing industries.

Top 2 benefits of 4 roll 4-roll plate rolling machine

A 4-roll plate rolling machine is a powerful and versatile tool used in metal fabrication and manufacturing processes. Unlike its 3-roll counterpart, a 4-roll plate rolling machine features two lower rolls and two upper rolls, arranged in a symmetrical configuration. This design offers several advantages and capabilities, making it a popular choice in various industries.

  • The primary advantage of a 4-roll plate rolling machine is its ability to achieve greater bending precision and control. The symmetrical arrangement of the rolls ensures balanced forces and consistent bending results, resulting in higher accuracy and better-quality bends. This makes it suitable for a wide range of plate thicknesses, from light gauge to heavy-duty applications.
  • Another benefit of the 4-roll design is its increased bending flexibility. With the ability to adjust the position and inclination of the upper rolls, a 4-roll plate rolling machine can perform complex bending operations such as double pre-bending, pyramid rolling, and cone rolling. This versatility expands the possibilities for creating various shapes and configurations with greater ease and efficiency.

Additionally, the symmetrical configuration of the rolls reduces the likelihood of material slippage during the bending process. This enhances the overall stability and reliability of the machine, minimizing the need for rework or corrections.

Technical data of 4-roll Bending Machine

ModelMax pre-bending thickness(mm)Max bending thickness(mm)Diameter of upper roller(mm)Max plate width(mm)Main motor power(kw)

Structure and main parts

The main structure

  • The machine is four roller bending machine, its structure is shown in the previous photo.
  • The top roll is the drive roll, its position fixed; rotate by the hydraulic station through the hydraulic motor.
  • The bottom roll and side roll are driven rolls and can be moved up and down, adopting hydraulic transmission.
  • Cylinders are on both ends of each roller, cylinders on side rolls ends are parallel, on bottom rolls are parallel and filled with oil at the same time. Overturn device on the front of top roll works by cylinders through leveraged institutions.
  • The bottom roll and side roll can be adjusted into a parallel position or tilted position, and the applied force of both bottom roll ends’ cylinders can be adjusted.
  • The Left and right frames are the main body of four roller plate bending machines, welded structure, a strong installed base in the welding machine, and the main drive and hydraulic drive are installed in the machine end.

4-roll vs 3-roll bending machine

  • All operations are on the bench in front of the machine.
  • Compared with a three-roller symmetric rolling machine, the four-roller plate rolling machine can do end pre-bending without any devices and less remaining straight edge.
  • Compared with a three-roller asymmetric rolling machine, it can bend rolls at a time without turning around the metal plate.
  • This improves the use ratio of metal plates, ensures the quality of the product, and the process is simple, flexible operation, high efficient.
  • Auxiliary of four-roll plate rolling machine adopts hydraulic drive, compared with mechanical transmission, its structure is simple and safe to use.

The main transmission mechanism

The top roll is the drive roll, which rotates with a speed of about 0-3.3m/min. the main transmission mechanism is provided motive power by motor-reducer through electrical control of hydraulic stations, fixed by spline shaft on the top roll, thereby the top roll can get the line speed of the design.

The auxiliary transmission

  • The bottom roll and side roll lifer adopt hydraulic drive. The principle of hydraulics is as follows in the drawing.
  • The transmission of the bottom rolls and side rolls are driven rolls, transmitted through the friction between metal plate and rollers. Bearings on the roll end slide by guide plate in the frame grooves, lift driven rolls by auxiliary transmission, drop by dead weight. Bearings on the bottom roll end are driven by the same cylinders served simultaneously.
  • Side roll ends are driven by a parallel cylinder structure, can be synchronized movements can also be adjusted individually.
  • The hydraulic system’s working pressure is 100 kg/cm2, maximum pressure of 160 kg/cm2.

Overturn device

The workpiece should be removed from the end of the top roll when finished. To this end, overturn the device set on the bearing body of the top roll end. The overturn locking bearing body during working and breaks away from it when removing the workpiece. After removing the workpiece, overturn reset, and the header close. Overturn device works with the cylinder too.

Operation Procedure and Method

  • Preparations: Lift down rolls near the top roll and the range is a bit more than the thickness of the metal sheet plate. Then remove the side roll of the feeding side to the same horizontal plane as the bottom roll then lift the other side roll to between the top and bottom rolls.
  • Feed: Feed the plant horizontally, make the end of the plate contact fully with the front side roll and make it correct then fall the front side roll to the original location.
  • Clamp the plate and pre-bend the end: Lift the bottom roll, clamp it, and adjust the pressure of the relief valve (according to the thickness, width, and material of the plate, pressure can be adjusted to 50-80 kg/cm2 at a time). Then adjust two reducing valves of the bottom rolls to no more than 50 kg/cm2. ( users can adjust the pressure of bottom roll clamping according to according to the thickness, width, material of the plate, and diameter. Not slipping is appropriate. Usually, 30-50 kg/cm2 range, and should note the pressure at both ends is the same.) Then stop the bottom roll, rotate the top roll counter-clockwise, steel plate follows to bend. At this point, the remaining plate should be 1.5 times the thickness of the plate. Then lift the back side roll, pre-bending the left end of the steel plate.
  • Pre-bend the other end of the plate: After pre-bending the left end, fall back side roll to the original location and rotate the top roll clockwise. Steel plate following to the above position and stop the top roll, lift the front side roll to pre-bend the right end of the steel plate.
  • The initial bending: Adjust both the front and back side roll to the designed station, rotate the top roll counter-clockwise, bending the plate center. Initial bending can be divided into several occasions.
  • Forming bending: Before adjustment, move the back side roller to the corresponding position of the workpiece needs, and start the top roller to the final bending.
  • Remove the workpiece: After finishing the bending, pull down the bottom roll to the end position, the workpiece following, turn over the overturn device, tilt the top roll, and remove the workpiece parallel to the top roll.
  • Note Note: If need to weld the workpiece onto the rolling machine, MUST be sure to make the welding ground contact with the workpiece directly. IT IS NEVER PERMITTED to make a plate rolling machine body to transition welding ground, so as not to damage the high-current displacement sensor and several significant impacts on the table!

Electric system

Electrical parameters

  • The total power:60HZ 220V, 3phase
  • Control power supply: 220V

Electrical theory

The machine is a PLC electrical control part of the core, together with the implementation of electrical control systems and hydraulic systems, machine tools to achieve the movement, and the main action button to the main console. The digital display shows the amount of the action moving, making the intuitive operation. Some of the major electrical appliances are the cabinet, and console components. Control has 10 buttons on stage.

  1. Power indicator: power control circuit box, access the power, the power directed to work;
  2. Emergency stop: to stop any action;
  3. Left side roller up or down: adjust both sides of the left side roller at the same time up or down;
  4. Bottom roller up or down: adjust both sides of the bottom roll at the same time up or down;
  5. Right side roller up or down: adjust both sides of the right side roller at the same time up or down;
  6. Top roll drive: drive the top roll clockwise or counter-clockwise;
  7. Reversing running: turn over the reversing device, and remove the workpiece.
  8. Reversing reset: Control overturned aircraft running and reset;
  9. Pump start: start the pump before beginning to work;
  10. Pump Stop: shut down the pump after finishing work;

Machine lubrication

Reasonably making the lubrication on the rotation crankshaft and sliding surface is an effective measure to reduce power consumption and increase machine life. Therefore, reasonable lubricating materials should be chosen and the necessary lubrication system should be established.

Lubrication way

According to work conditions and difficulty level to add oil, oil pump lubrication, box lubrication, and manual lubrication are used.

  • Oil pump lubrication should add thin oil timed and necessarily.
  • On the faying face of overturning and top roll gear, the two guide slots of control the overturn device, gearing of pinion and annular gear, there should be periodic manual lubricated.
  • The lubrication of the gear reducer and the bearing is with the help of splash lube oil in the gearbox.

The choice of lube oil

  • Oil cups and manual lubrication: recommended calcium-based grease or machine oil.
  • Lubrication in reduction box: recommended middle extreme pressure gear oil No. N220.

Lubrication system and announcements

  1. Before starting the plate bending machine, should make appropriate lubrication on oil pump, manual oiling, and gear oil tank as required。
  2. Continuous working, the lubrication of dry lubrication point is generally every two hours. A specific lubrication system should be built on the load and running conditions of the machine。
  3. Lube oil in the reduction gearbox should be replaced at least every six months 。
  4. The lubrication system should be washed at least once a year。

Installation and commissioning of Plate Rolling Machine

Installation of the machine

The equipment includes a complete machine, electric control cabinets, electrical cabinets, hydraulic stations, and other parts. Complete machine parts can be shipped disassembly and should be complete with no damage.


Plate rolling machine should be made commissioning and test qualified before work.

Preparation before test run

  1. Check whether the fastener joints are reliable.
  2. Check whether the oil cup lubrication point and manual surface lubrication are adequately and well lubricated.
  3. Check whether the reduction gears’ oil tank and oil level comply with the provision.
  4. Check whether the hydraulic piping system is installed correctly and firmly, with no damage, or leakage phenomenon.
  5. Check whether the rotation direction of the transmission motor of the gear oil pump is in order.
  6. Check whether the internal gear transmission is stuck.
  7. Check whether the electronic control system lines, power, voltage, and connector is good.

No-load test

Test Program

  • After ensuring the lubricating oil supply was sufficient, start the hydraulic transmission motor. When well-running, parting manipulate bottom roll and two side rolls to up and down within their respective 1 / 2 range of stroke. If both the roll ends can be raised and descent at the same time by tanks, then test in full stroke range. Individually raise and descent each roller 5 times. Series cylinders should be full of hydraulic oil before two side rolls start to ensure both ends to go up and down synchronously.
  • Test 5 times about tilt position raise and descent side rolls.
  • Test 5 times about overturning the device. Test 5 times about top roll tilting.
  • Top roll rotated CW and CCW every 15 minutes, cycle 2 times. Prompt braking action 5 times during the test.

Check during commissioning

  • Check the untaught bottom and side rolls’ contact with top rolls, should be no more than 0.2mm/m.
  • Check whether the bottom and side rolls are reposefully and neatly raised and descent.
  • Check whether the gear transmission system is reposefully and no noise.
  • During commissioning, reduction gear bearing temperature should not exceed 60 ℃. The sliding bearing temperature should not exceed 75 ℃.
  • Check whether the limit switch is flexible and reliable when overturning the device and falling down the device in an extreme position.
  • Check the electrical control system of the interlock device, and whether the control device is flexible and reliable.
  • Check whether the brake is accurate and reliable.
  • Check the hydraulic system of pumps, valves, and management is working correctly, and no leakage.
  • Check all the fasteners of the machine are loosening or not.

Load test

The no-load test is normal, before on the plate at room temperature under the load test of the machine. Take 10 mm thick, width2500 mm, the yield strength σs ≤ 245Mpa, smooth handling of the steel plate after bending test, successive load, fractional rolled into the required minimum volume curve φ = 500 mm diameter cylinder.

Load tests must meet the technical parameters of the largest rolling capacity and the performance requirements, at the same time fully inspect the assembly quality of the machine, and check the coordination of each working system. In all the active processes, all agencies should work smoothly, without impact, flexible, reliable, and exact action, rollers should not swing and the hydraulic system must not leak. The bearing temperature must not exceed the prescribed range, and rolls and plates should not have skidding during rolling.

Safe operation and maintenance

Safe operation matters

  • The operator should be aware of the machine’s structure, performance, skilled manipulation of control methods and the bending process, and strict compliance with the safe operation matters.
  • All the buttons of on the electronic control system must be placed in the original location before starting and stopping.
  • During use, should always check the oil supply situation in the lubrication points. Attention to the lubrication point oil suitable for the general operation. The plate bending machine should be lubricated once every two hours during working.
  • During working, in case of any irregular noise, shock, vibration, or oil spills should stop immediately to check.
  • During use, should always check the drive system and connecting parts, to keep no loosening, and no damage.
  • Strictly prohibit rolling the plate without leveling.
  • The plate should be perpendicular to the roller center line when bending.
  • The plate should roll following top and bottom rolls, with no skid during the bending process.
  • During the bending process, must stop the main transmission before rolling up-down and turn over the overturned device.
  • During the bending process, the bottom roll and side roll are not allowed up-down simultaneously.
  • Unloading workpiece by overturning when bottom and side roll down to a certain position.

Machine maintenance

Proper use and reasonable maintenance, can extend the life of the plate roller and can reduce the cost of repairs. The maintenance of this machine has the following main points:

  • The machine must be in normal operation and have good lubrication and strict implementation of the lubrication system.
  • Lay down regular inspection and repair system.
  • All wearing parts of excessive wear or loss of the original performance requirements should be promptly replaced, and the other parts if damaged should be repaired.
  • During use, department temperature should be paid attention to, bearing temperature must not exceed 75 ℃, and bearing temperature must not exceed 60 ℃.
  • hydraulic transmission system should be periodic inspection, cleaning, out of work hydraulic components should be replaced timely. Tank required to maintain the oil level, minimize contamination of hydraulic oil and check the deterioration of hydraulic oil at least every six months, if found exceeding the use boundaries, should be promptly replaced. Selection of hydraulic oil: higher temperature in the environment, recommended HJ30 machine lubricating oil; in low ambient temperature, recommended HJ20 machine lubricating oil.
  • All live parts of the electrical system should be properly grounded. Each electrical component should be periodically maintained, dedust, and timely replaced with the defective, failure of components.
  • The workplace does not allow random stacking quantity, oxide is promptly clean.

The maintenance of the plate rolling machine

Routine maintenance

  • Check whether the external structural parts of the sheet metal rolling machine are cracked, deformed, etc. and whether the forbidden firmware is loose.
  • Check whether the operation console and operation switches, limit positions, and indicator lights are normal.
  • Check the pipeline system for leaks.
  • Check the oil pump, solenoid valve, and oil cylinder for oil leakage.
  • Check whether there is any abnormality in the operation of the upper and lower rollers and the wear of the sliding bearings.
  • Check whether the pressure gauge is normal.
  • Check whether there is any abnormal noise when the motor is running.
  • Check and lubricate the lubricated parts: Reducer, Main drive open-gear, Upper roller lifting guide, Sliding bearings at both ends of the upper and lower rollers
  • Check the surface of the cleaning equipment for oil stains once a week.
  • The above maintenance items shall be borne by the operator.

First-level technical maintenance

According to the “daily maintenance” project, and add the following work.

  • Check whether the routes and accessories of the electrical system are intact.
  • Check whether the oil level in the hydraulic system oil tank is normal, and fill in the insufficient parts in time.
  • Check the operation of the hydraulic system, and check the performance status of the machine under the highest work.
  • Check the clearance of the lower bearing of the body of the plate rolling machine and the clearance of the sliding guide of the frame.
  • Check the open gear meshing.

Secondary technical maintenance – hydraulic system maintenance

  • Change the hydraulic oil every one to two years.
  • Empty the hydraulic oil in the crude oil tank when changing oil, check for magazines at the bottom of the oil tank, and clean the oil tank.
  • Each time the filter changes oil, the filter should be replaced or thoroughly cleaned.
  • The hydraulic control elements (valves) are cleaned as appropriate.
NoName of goodsQuantityUnit
1Main machine1set
2Operation Manual1piece
3foot screw1set
4Certificate of Quality1piece
5Packing List1piece
6Hydraulic station1set
7Electrical control counter1set
8Oil Gun1chase
9nozzle tip1set