Introduction to roll forming-roll form machine

Roll forming means giving shapes to sheeted metal, mostly round and conical. But roll forming also allows us to create angled shapes like rectangles and squares. They can be fitted with crowning systems, software, controllers, to deliver unmatched precision and quality. Because of their flexibility and versatility, plate rollers are a much-wanted machine system, in plants manufacturing everything from home appliances, to the ones we take to space.

There are different kinds of plate bending machine technology, but one working principle. In this article, we will explain plate rollers and give you some basic information about roll forming. Remember, when working with a plate rolling machine, it is crucial to delegate this task to experienced operators or train your team beforehand. 

Roofing machine for PV4 Aluzinc calamina sheet

Roll Forming Working Principle

Plate rollers are used to create O-shapes, U-shapes, and angular shapes by bending the material in different techniques. The working principle of a plate rolling machine is bending the material by pressing it in between rolls. There must be an upper and lower roll. From there, plate rolling machines have evolved, having two, three, or four rolls, different builds and designs.

The top roll serves as a pinch, to keep the material steady and well-placed, while the bottom rolls make a rotary motion, providing torque, thus forming the material. The sheeted metal undergoes this process back and forth until the desired shape is achieved. To create the details and edge bends, extra equipment is required. It needs to be said that the final product accuracy to the brief depends on the type of material, thickness, the position of the rollers, and other features.

Mechanical and hydraulic plate rollers

We can divide rolling machine systems into mechanical and hydraulic movement methods. For the classification of plate rolling machines by build and structure (number of rolls), check out our other article here.

The mechanical three-plate rollers can be symmetrical and asymmetrical. The symmetrical design has two bottom parallel rolls and the third is placed above, in the centre. The bottom rolls conduct the rotary motion, being the main drive in forming operations.

In the asymmetrical build, we have the upper roller acting as the main drive. This roll is placed above, another roll directly below, and the third one is on the side. Side rollers are very effective in pre-bending, which the symmetrical version can't do without extra equipment.

In hydraulic plate rollers, the upper roller is drum-shaped and can be lifted vertically, providing flexibility and straighter outcomes.

Cold or Hot bending?

There are many types of bending methods and techniques you can choose from, but before thinking of specific ways to roll a workpiece, you must think about hot bending and cold bending. Cold bending refers to every type of bending that doesn't use added heat to bend. This procedure is fast and inexpensive. However, it is not very advanced so if you are thinking to invest in a plate rolling machine, pick accordingly to your needs.

Hot bending, on the other hand, is very precise, advanced, and accurate. By heating a specific area in the workpiece, the area is easier to bend and manage. This method is also energy sufficient. A mix of these processes is warm bending. This method can make it easier to bend and cause fewer distortions, but risks of causing internal stress in the workpiece.

For more information, reach out to us, and we will share with you more details on the matter.

Pre-bending

When working with sheeted metal, the only place that undergoes the bending pressure is that one part between the rolls. Therefore, this method leaves a lot of material's "real estate" out of the bending area. This part is called the straight edge.

That's why operators need to execute the important procedure of "pre-bending". This technique helps with shrinkage and distortions. There is a theory that can calculate the residual straight edge, based on the bending form (symmetrical or asymmetrical) and the thickness of the plate.

According to the process, operators can use one of the following methods:

• Press bending
• Template roll bending
• Block roll bending
• Cushion block liquid bending

When rolling materials, make sure to centre the workpiece correctly. This will prevent torsion and contribute to a more accurate product. You can use side roll centring, side roll slotting, inclined centring, etc.

As a final note, we always advise shop floor professionals to make an assessment before deciding. If you need more guidance in this process, you can contact our technical sales team to provide you with valuable insights for a beneficial purchasing journey.