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Roll Bending Process and Roll Bending Machine

Bending roll and 3D guide roll of profile bending machine

Roll bending form profiles either with cold bending, although it is one of the most complicated fabrication processes, roll bending is essential if you want to provide your customers with more bending options.
However, unlike a press brake, which delivers a single bend in one direction of inertia, a roll-bending machine features multiple forces and different courses when the roll-bending process is taking place.

Roll bending is an art, this article provides some insightful tips on how to select the best bending process or roll bending machine for your roll bending project.

Roll bending

Roll bending is a cold bending process whereby we obtain cold process deformation with a wider bend radius, the metal profile or steel plate is made to pass through a set of three rollers that, will form an arch with the required radius of curvature. Roll bending process in which tubes, steel/aluminum plates, and metal profiles are repeatedly passing it through a set of 3 adjustable rollers resulting in bending progressively, will form an arch or circle with the required radius of curvature. Theoretically, the cold roll bending process can range from 5 times the cross-section to infinity. Read More: Roll Bending VS. Bending: What’s the Difference?

Type of roll bending machines

The roll bending machines can be divided into two-roller, three-roller, and four-roller roll bending machines.

2 roller roll bending 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, 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 bending rolls.

3 roller roll bending machine

bending process of section bending machine

The three-roll roll bending machine is the industry workhorse, they are driven by a hydraulically or electric motor. A 3-roller roll bending machine(such as 3 roll steel plate rolling machine) is a mechanical jig having three pressure rollers(Both three- and four-roller roll bending machines have fixed-position top rolls and two offset, or lateral, rolls, one on each side.) used to bend a metal profile(tubes/pipes, steel/aluminum plates, metal profiles, H-beams, angle irons, etc) into a circular arc. The pressure rollers freely rotate about three parallel axes, which are arranged with uniform horizontal spacing. Roll bending pushes an extrusion around three different pressure rollers placed in a triangular shape. The pressure rollers are adjusted to form a precise angle, up to a 360-degree rotation, that can roll horizontally or vertically.

Read More: 3 Roll Profile & Plate Bending Machine: 5 Types, 4 Benefits

4 roller roll bending machine

The working principle of 4-roll bending machine
4 roller roll bending machine work principle

The 4-roller roll bending machines have an additional roller underneath the top roll, which constantly pinches the metal profile/plate during rolling. Double-pinch rolls can prebend both metal profile ends without removal, as is required with single-pinch rolls.

Three-roller roll bending machines generally require pre-bending the leading end, running the metal profile/plate through the machine to prebend the trailing end, and then switching the roll rotation direction to roll the circle body. Four-roller roll bending machines have a slight advantage in cycle time because they permit bending of the leading edge, rolling the cylinder body, and finishing off the trailing prebend, all while rolling in the same direction.

Four-roll roll bending machines generally are the only equipment with NCs or CNCs because the fourth roll provides constant pinching action, minimizing the chance for slippage. Automatic controls use an encoder to track the movement of the plate through the machine. If the plate slips, the bending roll movements will be out of sync with the rolling movement.

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