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Plate Rolling Machine: Basics, 4 Types & Principles, Choose Tips

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plate rolling

What Is Plate Rolling Process?

Plate Rolling/Plate Bending is a unique process whereby a flat sheet(plate metal) of steel, aluminum, stainless or other material is formed into circular or other shapes by force through a set of powered rollers. Machines consisting of 2 to 4 roll sets press, engage, and form the material through the force of electrically, mechanically, or hydraulically driven means. Typical applications include the manufacture of items such as cans, tanks, pipes, pressure vessels, tanker trailers, excavator buckets, and other rounded metal pieces.

plate rolling
plate rolling

The plate rolling process can be either computer controlled or operated as a powered manual machine. However, even with CNC controls, material variations can require adjustments and operator finesse in order to achieve the desired results.

What Is a Plate Bending Machine?

A plate bending machine is a piece of equipment, are designed to be able to roll bending a variety of various types of sheet metal(plate metal) thicknesses and diameters, that is used to roll into a round, semi-round, round with varying radii or conical shapes (some machines specialize in rolling materials back to flat too!).

plate rolling machine
pressure vessel fabrication equipment: plate rolling machine

Work Principle

The plate bending machine boasts a working mechanism that allows it to bend flat sheet metal into a large arc or cylinder or even a square, an ellipse shape, and a multi-section arc. Utilizing a series of precise and strong hardened rolls powered by either hydraulic or mechanical methods, the rolls are brought into a pitching position with the material desired to be shaped. Once the material is firmly held between two of the rolls, a third and sometimes fourth roll is brought into position pushing the material causing the initial bend, or what is referred to as the pre-bend. The rolls then begin to rotate pulling material through the pinched rolls and past the pushing rolls forcing an arc into the material.

4 Basics of Plate Bending Machine

However, there are limitations due to the physical properties of the plate roll machine’s design. Therefore, these plate bending machines are best suited for the “ranges” of a user’s need.

  1. The limitations of the Plate Roll have to do with a combination of the roll’s diameter (the smaller the roll the tighter the diameter that can be rolled, while the larger the roll, the less deflection is produced), the diameter being rolled, and the workpiece’s thickness.
  2. All rolls will pinch the material between two rolls and (by mechanical or hydraulic means) force the workpiece material into an arc.
  3. Both ends of a turning roll must be securely supported to prevent the rolls from springing apart under pressure.
  4. One end of the roll is called the “drop end” as the roll support on that end can be released either manually, hydraulically, or mechanically to remove the rolled cylinder from the top roll.
plate rolling machine
plate rolling machine

3 Types of Plate Bending Machines

Plate rolling is an incredibly essential process of metal fabrication. Since most of the products created during plate rolling are sophisticated, cutting-edge, and unique, they are created using specialized equipment that is known as the plate rolling machine or the plate bending machine. Since not all rolled metals are created equal, every project may require a specialized type of plate roll machine. Some of the standard metal rolling machines include:

  • Type 1#: 2 Roll Bending Rolls
    • 2 Roll Machines (Ideal for thin, highly repetitive circular rolling such as Food Cans)
  • Type 2#: 3 Roll Bending Rolls
    1. Initial Pinch (Most popular design due mostly to cost)
    2. Double Pinch (Affordable design for heavier bending applications)
    3. Variable Translating Geometry Bending Rolls
      • Top Roll Variable Geometry Plate Rolls (Affordable Design for Variable Radii applications)
      • Variable Translating Geometry (Affordable Design for Variable Radii applications)
  • Type 3#: 4 Roll Bending Rolls
    • 4 Roll Double Pinch (The most versatile of the designs)
      Vertical Rolls (Perfect when rolling very large Radii such as above-ground fuel and water storage tanks)
      Automated Cycle & Specialty Rolls (Spiral Duct Rolls, Corrugated Material Rolls, etc.)

2 Roll Plate Rolling Machine

The 2 roll style plate rolling machine is typically used for high-volume processing of thin metals (typically 3/16” and thinner) into small diameter shapes (4”- 24” Diameter).

WorkPrinciple

The rolls are mounted in a vertical pattern with one roll being centered directly on top of the other. The forming roll (typically the lower of the two rolls) has a durable but flexible coating of neoprene or similar material that the upper roll pushes into creating a depression and “waves” around the point of contact. The operator feeds the workpiece into this pinched position as the rolls are turning and the deflected rubber material forces the workpiece into a rolled form around the solid roll.

Advantages

  • Very fast rolling operation.
  • Easy to automate.
  • No flat on rolled shape.

Disadvantages

  • Limited to thin materials.
  • Limited adjustment.

Initial Pinch Plate Rolling Machine

Probably the most common type of plate rolling machine found is the Initial Pinch. This type of material roller consists of 3 rolls with 2 of the rolls mounted almost directly vertical over one another with one being a fixed roll and the other adjustable. The last roll is offset on an adjustable slide that is controlled in a motion towards the “pinch” point of the two rolls. To operate this roll, the operator inserts the workpiece material and adjusts the movable of the two vertical rolls until the workpiece is firmly “pinched” between the two rolls. Next, the offset rolls are positioned upwards towards the fixed roll forcing the workpiece to bend around the fixed roll. The rolls are then powered on and the rolling process begins with adjustment to the offset roll to reach the desired diameter.

Advantages

  • Very common roll.
  • Easy to operate.
  • Typically used in thin material applications (1/4” or less).

Disadvantages

  • Material must be turned around or fed all the way through the machine to “pre-bend” trailing edge of workpiece.
  • Adjustments are not exact and must be checked and rechecked during rolling process.

Double Pinch Plate Bending Machine

This type 3 roll plate bending machine of roll is commonly used for medium plate applications. The top roll is fixed and the bottom two rolls are movable at an angle towards the top (fixed roll) or the bottom two rolls are fixed with the top roll being movable. Material is fed in until it rests on the bottom two rolls. The rolls are then brought together with the top roll until the desired position is achieved to obtain the correct diameter; at which time the rolling process begins.

Advantages

  • Very common roll.
  • Easy to operate.
  • Typically used in medium material applications (1/4” – 3/4”).

Disadvantages

  • Large flats are left on the end of the material.
  • Adjustments are not exact and must be checked and rechecked during rolling process.
  • Material is never fully “pinched” between rolls and can slip • Material is fed in at an angle.

4-Roll Plate Roller

This type of plate roller is the only type where Computer Numerical Control of the rolls makes a great deal of sense as this is the only plate roll that can easily roll oblongs or out-of-rounds shapes. This roll has two rolls centered vertically over one another and two movable rolls positioned directly on either side of the center, or “pinch,” rolls.

Workprinciple

These movable rolls can be positioned at an angle from well below the material to where the centerline of the positioning rolls outside diameter can almost meet the pinch point of the “pinch” rolls. In order to operate this machine, the operator first positions the “Leading” roll as a material stop or gage.

The opposite roll is positioned where the diameter of the acts like a material support assisting in loading by allowing the material to be supported across the top diameter. The pinch rolls are opened and material is inserted and squared against the “leading” roll. The pinch rolls are then pressed together and the material is slightly retracted by rolling the pinch rolls backward. The leading roll that was positioned as the material gage is then lowered to allow the leading edge of the workpiece to pass over it.

As the rolling begins, the leading roll that now forces the material up into the desired radius. Rolling continues until the trailing edge of the workpiece is close to passing the “trailing” role that was initially used as a support. The “trailing” roll now forces the trailing edge of the material up into the final position to achieve the proper diameter. If these rolls are controlled via numerical control, the “Leading” roll and the “Trailing” roll can automatically adjust position and roll oblong, egg-shaped or other non-round parts.

Advantages

  • Material is always firmly pinched.
  • Flats are minimized due to adjustment of both leading and trailing rolls.
  • Can be used for almost all material thickness applications.
  • Material is fed into unit flat.
  • Machine can save a great deal of space as material does not need to be rotated around & fed in backward to pre-bend the opposite end.
  • Can roll non-round shapes.

Disadvantages

  • Price.