What is metal plate rolling?
To start with, metal plate rolling is a type of plastic deformation that permanently and irreversibly changes the shape of metal profiles and sheets. Among the various forms and shapes that steel comes in, sheet or plate metal is the most versatile and easiest to work with, making sheet or plate metal rolling machines our most popular product.
The plate rolling process is a deformation operation that allows giving the metal sheet or plate a certain curvature. This process takes place thanks to the steel plate rolling machine, which allows the passage of the metal sheets in 2-roll, 3-roll, or 4-roll plate rolling machines. And according to the pinching, the correct positioning of the rolls and their rotation, which can take place manually from the control desk or with numerical control, generate cylindrical pipes, conical or polycentric shapes of different thicknesses.
Sheet or plate metal is usually bent to increase its stiffness and strength and change its appearance for its final use, usually for much heavier applications such as cargo ships, rail and road fluid tankers, wind towers and turbines, and pressure vessels.
Rolling Sheet and Plate
The plate rolling process is similar to forming sheet metal with a press brake; it comes down to understanding the properties of the material and how pressure from the rolls can affect those properties. A good example is a result of forming in the press brake when each material piece is different; each will form, or roll, differently than the last piece.
Operating Parameters of the Plate Bending Machine
Metal Plate Rolling Machine‘s correct usage determines the production efficiency of the factory. All machines are really designed to function best when used to half their working value.
Begin with selecting the correct machine to roll the part on. Modern plate rolling machines are usually cambered (crowned) at 50% of the full-rated value of the machine. Therefore, a 1-inch machine is cambered to roll a 1/2-inch plate. All plate rolling machines are really designed to function best when used to half their working value.
Problems arise when the upper limits of any machine are approached, be it roll former or press brake. That means that even a small increase in thickness can make a difference in the way the rolls will perform. For example, if a .625- inch plate is rolled through a 1.000-inch rated machine, a small degree of barreling will likely occur.
CNC capacity of CNC plate rolling machine
A CNC plate rolling machine’s “CNC capacity” is not its “rated capacity” or “pre-bending capacity.” It is something less, usually about 40% of its rated capacity.
Consider a machine with a rated capacity to roll up to 1-in.-thick, 36,000-PSI-yield-strength steel in multiple passes. This means the machine can roll this material down to a diameter between three and five times the top-roll diameter, depending on the manufacturer. This same machine rolling the same material would (again, depending on the manufacturer) likely have a pre=bending capacity of 0.625 in. over multiple passes, down to a minimum rolling diameter between 1.2 and 1.5 times the top-roll diameter, with the flat ends between 1.5 and 2 times the material thickness. Minimum diameters as tight as 1 times the top-roll diameter are achievable on certain material thicknesses.
Plate Rolling Diameters
Minimum Diameter: The minimum diameter is the smallest diameter you desire to roll your material into. Use the factors 1.5X the top roll diameter for easy, no problem, rolling in one pass to achieve this goal. 1.3X the top roll diameter can be achieved with multiple passes or material at a shorter length then the full width capacity of the pallet roll. 1.1X the diameter of the trop roll is also achievable in softer materials less then the full width of the rolls AND utilizing a multipass technique.
Part of taking roll forming out of the realm of “black magic” is selecting the right-sized roller for the job. A good “rule of thumb” for 3-roll plate roller and 4-roll plate rolling machines is that you can roll a sheet or plate at 1 1/2 times the upper roll diameter, but that is not the case for the 2-roll urethane roller. If the top roll has a 10-inch-diameter, the minimum best practice “rollable” inside diameter will be 15 inches. Almost all machines achieve precise measurements working at 50% of the full rated value of the roll.
Essentially, the smaller the diameter of the roll, the more pressure you’ll need and thus the more yield in the rolls you will have. If you want to roll a thick plate with a small diameter, you should pay attention to how the upper roll and how the structure of the plate rolling machine is positioned. This is because these are the two crucial elements that affect the size of the opening and its quality. Theoretically, a plate rolling machine can roll material to a diameter of 1.5X the top roll diameter and in some applications even down to 1.3X However this is entirely dependent on the material itself and the capacity of the plate rolling machine you are using.
9 safety rules for plate rolling
- First and foremost, always wear appropriate and complete Personal Protective Equipment (PPE) before approaching and operating bending equipment.
- Before operating the tool for bending, read and understand its instruction manual, focusing on the machine’s functioning and working principles.
- Every new operator should be appropriately trained before using the machine for the first time, preferably by an experienced engineer well-versed in bending machine safety precautions.
- File metal burrs properly, and avoid touching metal edges or cuts, even while wearing gloves.
- Wet metal sheets should be given extra attention and handled with the utmost care.
- The sheet metal should be placed parallel to the bending machine before starting the operation.
- When working in cold weather, warm up the machine before use to ensure efficiency and reduce the risk of stressing the machines.
- The machines should be inspected regularly before each operation, especially before the initial startup.