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A Brief History of Modern Plate Rolling Machines – 2022

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plate rolling

Plate bending process

The plate roll bending process is the technique of choice for any metal that are relatively thick, it is the primary manufacturing process for metal bending large pieces of plate.

Roll bending uses either two, three, or four rolls to feed and bend the plate to the desired curvature.

At the three or four-roll plate bending machine, the arrangement of the rollers determines the exact bend of the work. Different curves are obtained by controlling the distance and angle between the rollers. Moveable rollers provide the ability to control the curve.

The evolution history of the drive mode of the plate bending machine

  1. The early plate bending machines would be small and could be directly hand-driven or by a geared handle to give some mechanical advantage.
  2. After that, the introduction of the steam engine into plate bending factory production, where the driving power was transmitted from the steam engine into the workshop via a line shaft, this new source of power enabled plate bending to move towards thicker plate being rolled, and not just thin metal sheets by a hand driven roller.
  3. The introduction of electric motors resulted initially in the plate bending rolls, which were previously driven by steam-powered line shafts, now being simply converted. Many plate bending machines, even in 1940, could be seen that were originally line shaft driven using a flat belt and had been subsequently retro-fitted with their own electric motor.
  4. In the late 1950’s the use of hydraulics was used and a double pinch 4-roll design was made in 1960’s.
    The introduction of hydraulics into the design of plate bending machines then became a necessity and a natural transition. The advantage of hydraulics is that you can apply a huge force and have full control of the amount of this force by simply controlling the pressure in a hydraulic cylinder or ram, as it is sometimes called. It also had the advantage of being able to stop bending instantly.

A brief history of the development of five kinds of plate rolling machines

Initial pinch bending rolls

The plate rolling machine in the early 19th century was in the form of an initial pinch, and used for light sheet and hand driven bending rolls.
These were used by sheet metal workers for chimneys and ducting of air and would have typically had 80mm diameter rolls for rolling plate up to 1mm thick.

The most common design for heavier plate bending rolls was the pyramid roll layout, and the position of the top roll would initially be by a hand screw which could be geared, followed by a powered drive. Initially this was by line shaft using a power transfer lever and later by a separate electric motor.

Pyramid plate bending machine

The principal problem with the pyramid-style plate bending rolls is the flat section on each end of the plate, resulting from the distance between the two bottom rolls. The length of these flat ends would naturally be approximately equal to the distance between the bottom and centre roll. This distance would be larger when rolling a plate to a large diameter cylinder and smaller when rolling a plate to small diameter cylinder. The most straight forward way to deal with this was to cut the flat ends off each end after the first stage of the rolling work and then put the plate back into the plate rolling machine and continue to roll the plate until it formed a cylinder.

4-roll bending rolls

In the 1960’s, the plate rolling machine has a double pinch 4-roll design.
The 4 roll double pinch plate bending machine design enabled the plate to be pre-bent in the rolls, and having the second outer roll it was possible to pre-bend both ends of the plate without the need to withdraw the plate and turn it around.

3 Roll double pinch plate bending machine

Towards the end of the 1960’s, an alternative design was introduced which was the 3 Roll double pinch plate bending machine. This arrangement used a planetary system of gears and the two bottom rolls pivoted on a swing arm mechanism. The top roll was in a fixed position as was the drive gear wheel to the two planetary gears. It was then straight forward to install a chain drive to the top roll. This driven gear was powered by a hydraulic motor with variable speed.

Similar to the 4-roll double pinch plate bending machine, this design also allowed pre-bending both ends without turning the plate. 3 roll drive and variable speed was another huge step forward and is the design that many medium size machines use today.

Variable geometry plate bending machine

In the period since the early 1970’s, all 3 rolls on larger plate bending machines were now very often driven by independent hydraulic motors.
At the same time, there is a variable geometry plate bending machine, where the layout is similar to the pyramid roll with the top roll moving vertically but the two bottom rolls can also move horizontally.

Works Cited: BARNSHAWS