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3 Types of Plate Rolling Machine Working Principle

3 roll bending machine

Definition of Plate Rolling Machine

The plate rolling machine is also known as a plate bending machine and plate roller. It is a type of sheet metal bending equipment that utilizes work rollers to produce sheet metal round processing and forming. It can form parts of different shapes such as cylindrical parts and conical parts. It is a piece of very important sheet metal bending processing equipment.

Debugging Pltae Rolling Process of Ø9000mm Wind Tubular Tower

Plate rolling machine working principle

Plate rolling machines can be divided into two-roller, three-roller and four-roller. The three-roll plate rolling machine can be divided into two types: symmetrical and asymmetrical.

bending process of four-roll section bending machine
4-roll bending machine

Introduction and working principle 2-roll plate rolling machine

The 2-roll plate rolling machine is a type of equipment that boasts two rollers, an upper rigid metal roller, and the lower elastic roller. The sheet material is passed in between the rollers, and when force is applied, the metal adheres to the power assuming a cylindrical shape. Used on thin metals for high production operations (filters, canisters, etc.)

The 2-roll plate rolling machine is configured with polyurethane roll which, by exerting dynamic pressure, speeds up the plate forming process, assuring the straight end of the produced rolls is removed and greatly simplifying the prebending-rolling-prebending sequences typical of 3-roll or 4-roll steel plate rolling machines.

Working principle of 3-roll and 4-roll plate rolling machine

The working principle of the plate rolling machine is the same as that of the profile bending machine according to the principle of three points forming a circle, the relative position change and rotational motion of the workpiece are used to produce continuous plastic deformation of the plate to obtain a workpiece with a predetermined shape. According to the rotational movement and position changes of work rolls of different shapes, elliptical parts, arc parts, cylindrical parts, and other parts can be processed.

Plate rolling machine working principle
Figure 7-1 Working principle of plate bending machine: a: symmetric 3-roller plate bending machine; b: asymmetric 3-roller plate bending machine; c: 4-roll plate bending machine

Working principle of symmetrical 3-roll plate rolling machine

3 roll bending machine
steel plate rolling machine

The picture above (a) is a cross-sectional view of the rollers of a symmetrical 3-roll bending machine. The rollers have a certain length in the axial direction so that the entire width of the sheet is bent.

There is an upper roller 1 at a symmetrical position in the middle of the two lower rollers. The upper roller can be adjusted in the vertical direction so that the sheet material 4 placed between the upper and lower rollers can obtain different bending radii. The lower roller 2 is active and is installed in a fixed bearing. The motor rotates in the same direction and at the same speed through a gear reducer. The upper roller is passive and installed in a bearing that can move up and down. The adjustment of the rollers on the large plate rolling machine is mechanical or hydraulic, and manual adjustment is often used in the small plate rolling machine.

When working, the sheet material is placed between the upper and lower rollers, and the upper roller is pressed down to make the sheet material bend between the support points. When the two lower rollers rotate, the sheet material moves due to the action of friction, so that the entire sheet material is evenly bent.

According to the above bending principle, the required bending radius can only be achieved when the part of the sheet material is in contact with the upper roller, so the edges of both ends of the sheet have a length that does not contact the upper roller and does not bend, which is called The remaining straight side, the length of the remaining straight side is about half of the distance between the two lower rollers.

Working principle of asymmetric 3-roll plate rolling machine

Figure 7-1(b) is the bending drum diagram of the asymmetric three-roll plate bending machine. The upper roll 1 is located on the top of the lower roll 2, and the other roll 3 is on the side, which is called the side roll. The upper and lower rollers are rotated by the same motor. The lower roller can be adjusted up and down, and the maximum distance of adjustment is approximately equal to the maximum thickness of the steel plate that can be bent. The side roller 3 is passive and can be adjusted in the inclined direction.

When bending, sheet material 4 is fed into the upper and lower rollers, and then the lower roller is adjusted to compress the sheet material to generate a certain frictional force, and then the position of the side rollers is adjusted. When the upper and lower rollers are driven by the motor to rotate, the sheet material is bent.

The advantage of this asymmetric three-roll plate bending machine is that the edges at both ends of the plate can also be bent, and the length of the remaining straight edge is much smaller than that of the symmetrical three-roll plate bending machine, and its value is less than twice the plate thickness. Although the sheet material cannot be bent between the side roll and the lower roll, the whole bending process can be completed as long as the sheet material is taken out from the rolling machine and then turned around and bent.

The working principle of the 4-roll plate rolling machine

4 roll bending machine

Figure (c) is a four-roll plate rolling machine, which is basically similar to the asymmetric three-roll plate rolling machine, except that one side roller 3 is added. It eliminates the trouble of turning around and bending the sheet on the asymmetric three-roll rolling machine.

Radius of curvature

The plate rolling machine basically consists of three parallel steel rollers, arranged similarly to the vertices of an isosceles triangle.
The sheet metal when passes between the lower and upper rollers change its shape and undergo a curvature, known as the radius of curvature. This so-called radius depends on the mutual position of the three steel rollers.

Deformation Analysis of the Bending Process

According to the characteristics of rolling deformation, the plate rolling process can be divided into elastic deformation, elastic-plastic deformation, and pure plastic deformation stages.

In the initial stage of the bending of the barrel blank, the external bending moment is not large, the value of the internal stress is less than the yield limit σs of the material, and only elastic deformation is caused inside the blank, which is called the elastic deformation stage. When the value of the external bending moment continues to increase, the internal stress exceeds the yield limit, and the deformation in the deformation zone of the blank transitions from elastic deformation to elastic-plastic deformation and pure plastic deformation.

Plate rolling machine working principle
a—elastic deformation; b—elastic-plastic deformation; c—pure plastic deformation

Deformation Analysis

As can be seen from the above figure, the upper stress of the blank section transitions from the outer tensile stress to the inner lamination stress, and there must be a layer of metal in the middle, whose tangential stress is zero, called the stress neutral layer, and its curvature radius is represented by ρσ. Similarly, the distribution of strain transitions from the tensile strain of the outer layer to the compressive strain of the inner layer, and there must be a layer of metal with zero strain in between, that is, when the coil is deformed, its thickness remains unchanged, which is called the strain neutral layer, and its radius of curvature It is represented by ρε. This is the basis for accurately calculating the unrolled size of the round blank. When the deformation is small, ρσ=ρε=r+t/2, that is, the stress neutral layer and the strain neutral layer overlap, and in the middle of the blank thickness, when the deformation is large, the stress neutral layer and the strain neutral layer are opposite to each other. Inward displacement and the displacement of the stress neutral layer is greater than the displacement of the strain neutral layer, that is, ρε>ρσ, in the production of coiled plates, the following empirical formula can be used to determine the position of the strain neutral layer, namely

ρε=r+xt (7-1)

In the formula: ρε——curvature radius of strain neutral layer, mm; r——involution circle radius, mm; x——coefficient related to the degree of deformation, take x=0.33; t——material thickness, mm.

Top 8 Applications of Plate Rolling Machine

A plate bending machine, also known as a plate rolling machine or a roll bending machine, is used to bend and shape metal plates and sheets into curved or cylindrical forms. These machines are widely used in various industries that require the fabrication of components with curved surfaces. The primary purpose of a plate bending machine is to provide the means to transform flat metal sheets into different shapes, such as cylinders, cones, and segments.

Cylindrical Tanks and Vessels

Plate rolling machines are indispensable for shaping metal plates into cylindrical tanks and vessels across industries. These machines utilize controlled pressure and precision to curve metal sheets into the required cylindrical forms. By adjusting roller positions and manipulating the bending process, plate rolling machines ensure consistent curvature and meet stringent dimensional tolerances. This capability is critical for constructing leak-proof containers capable of holding liquids or gases under pressure. Industries such as petrochemicals, oil and gas, food processing, and manufacturing rely heavily on plate rolling machines to fabricate cylindrical components essential to their operations. The use of plate rolling machines guarantees efficiency, accuracy, and safety in the production of cylindrical tanks and vessels, reinforcing their vital role in various industrial sectors.

Pressure Vessels

Pressure vessels, critical for storing fluids under high pressure, often rely on plate rolling machines. These machines shape the cylindrical segments essential to vessel construction. Plate rolling machines bend metal plates into precise curves, ensuring compliance with tight dimensional tolerances. By adjusting roller positions and pressure, these machines guarantee consistent curvature, essential for structural integrity.

Pressure vessels demand precision and adherence to rigorous standards. Plate rolling machines contribute to the vessel’s reliability by producing curved components that meet required specifications. The machines’ versatility in handling different metals and their ability to accommodate complex shapes make them invaluable in pressure vessel fabrication.

Efficiency is another advantage. Plate rolling machines streamline the process, reducing the need for additional machining. Additionally, these machines ensure uniform stress distribution across curved components, enhancing vessel safety under pressure.

Architectural and Structural Components

Plate rolling machines are essential in creating architectural and structural components for various industries. These machines bend metal sheets into specific shapes, catering to the aesthetic and structural demands of construction projects.

  • Architectural Features: Plate rolling machines shape curved and cylindrical components used in architectural designs. They fabricate curved facades, arches, domes, and other distinctive elements that add visual interest to buildings. These machines ensure that the architectural features maintain precise dimensions and curvature, contributing to the overall aesthetic appeal of the structure.
  • Structural Elements: Plate rolling machines are crucial for producing structural components like beams, columns, and trusses. These elements may require curved or tapered shapes to accommodate architectural designs or structural requirements. By bending metal plates accurately, plate rolling machines help create load-bearing components that meet engineering standards and support the integrity of the building.
  • Efficiency and Precision: Plate rolling machines streamline the production of architectural and structural components. They offer efficiency by bending large metal plates into precise shapes, minimizing the need for extensive manual labor or complex fabrication methods. The machines’ precision ensures that each component aligns correctly, reducing the risk of errors and rework during assembly.
  • Customization: Different architectural and structural designs call for unique shapes and sizes. Plate rolling machines can be adjusted to accommodate specific design requirements, enabling the creation of customized components that fit seamlessly into the project’s overall vision.
  • Materials Diversity: Plate rolling machines work with a variety of materials, including steel, aluminum, and alloys. This versatility allows architects and engineers to select the most suitable material for their project’s structural and aesthetic needs.


In shipbuilding, plate rolling machines are indispensable tools that contribute to the construction of various components used in ships and vessels. These machines are crucial for forming metal plates into specific shapes required for the hull, decks, and other structural elements of ships.

  • Hull Construction: Plate rolling machines are used to bend metal plates into curved sections that form the hull of ships. The machines create consistent and accurate curvature for the hull’s structural integrity. The ability to shape metal plates precisely ensures that the hull can withstand the stresses of navigation and maintain watertight integrity.
  • Decks and Bulkheads: Plate rolling machines are instrumental in fabricating curved or inclined decks and bulkheads. These components contribute to the overall strength and stability of the vessel. The machines allow shipbuilders to create curved sections that fit seamlessly into the ship’s design.
  • Cylindrical Tanks and Pipes: Plate rolling machines produce curved sections used for cylindrical tanks, pipes, and ducts within ships. These components are critical for storage, fluid transportation, and ventilation systems onboard vessels.
  • Efficiency and Accuracy: Plate rolling machines streamline the shipbuilding process by efficiently shaping metal plates into the required forms. The accuracy of these machines ensures that components align correctly during assembly, reducing the need for adjustments and rework.
  • Material Versatility: Plate rolling machines work with a range of materials used in shipbuilding, including various grades of steel. This versatility allows shipbuilders to select materials that suit the vessel’s intended use, whether it’s a cargo ship, tanker, or naval vessel.
  • Customization and Design Flexibility: Ship designs vary widely, and plate rolling machines offer the flexibility to create customized components according to specific ship design requirements. Whether it’s a passenger liner, research vessel, or naval warship, these machines contribute to realizing unique design visions.

Industrial Equipment

In the realm of industrial equipment manufacturing, plate rolling machines are pivotal tools for crafting components with curved or cylindrical shapes. These machines are employed to shape metal plates into parts like conveyor rollers, cylinders for hydraulic systems, and specialized machinery components. By imparting controlled pressure and curvature, plate rolling machines create precise, load-bearing structures integral to various industrial processes. Their efficiency and accuracy contribute to the fabrication of components that withstand rigorous industrial environments, ensuring the reliable operation of machinery and systems across diverse sectors, including manufacturing, mining, construction, and materials handling.

Automotive Industry

In the automotive industry, plate rolling machines play a vital role in shaping metal components used in vehicle manufacturing. These machines are used to bend metal plates into specific curved or cylindrical forms required for various automotive parts. Plate rolling machines are essential for producing components like exhaust pipes, chassis parts, structural elements, and body panels.

The machines’ precision ensures that these components align accurately during assembly, contributing to the overall structural integrity and safety of the vehicles. Whether it’s creating curved sections for exhaust systems or forming intricate shapes for body panels, plate rolling machines offer efficiency and accuracy in producing parts that meet the stringent requirements of the automotive industry. Their ability to work with different materials, such as steel and aluminum, makes them versatile tools in the production of vehicles with varying specifications and designs. Plate rolling machines contribute to the efficiency, quality, and reliability of automotive manufacturing processes, helping to create vehicles that are both functional and aesthetically appealing.

HVAC and Ductwork

In the HVAC (Heating, Ventilation, and Air Conditioning) industry, plate rolling machines are instrumental in shaping metal sheets into curved and cylindrical components for ductwork and ventilation systems. These machines are used to form ducts, pipes, and fittings that facilitate the movement of air within buildings.

Plate rolling machines create precise bends and curves in metal sheets, ensuring that ductwork components fit together seamlessly. Whether it’s circular, oval, or rectangular ducts, these machines provide the necessary curvature for efficient air circulation.

Ductwork is a critical component of HVAC systems, allowing air to be transported to various areas within a building. Plate rolling machines contribute to the fabrication of ducts that are structurally sound, leak-resistant, and capable of maintaining proper airflow.

By utilizing plate rolling machines, the HVAC industry can efficiently produce customized ductwork that conforms to specific building layouts and design requirements. These machines enhance the manufacturing process, ensuring that ducts and components are accurately formed and contribute to the optimal performance of heating and cooling systems in residential, commercial, and industrial settings.

Custom Fabrication

Plate rolling machines are integral to the world of custom metal fabrication, enabling the creation of unique and specialized components tailored to specific design requirements. These machines are essential tools for transforming flat metal sheets into curved, cylindrical, or intricate shapes that meet the diverse needs of various industries.

Custom fabrication projects often demand components with precise dimensions, curvatures, and tolerances. Plate rolling machines excel in this regard by delivering accurate and repeatable results. They can shape materials such as steel, aluminum, and alloys, catering to a wide range of applications.

From artistic sculptures to specialized industrial machinery, plate rolling machines contribute to the realization of innovative ideas. By offering versatility in producing custom curves and contours, these machines empower fabricators to bring their creative visions to life and meet functional specifications.

Whether in architectural features, automotive modifications, or specialized equipment production, plate rolling machines play a pivotal role in transforming raw materials into customized components that adhere to exacting standards. They ensure that each project maintains its uniqueness while delivering structural integrity, precision, and efficient production in the realm of custom fabrication.


The specific application of a plate bending machine depends on the industry’s requirements, the types of materials being used, the desired shapes, and the precision needed. These machines are valuable assets in industries that require versatility, accuracy, and efficiency in shaping metal components with curved geometries.