Steel plate rolling can be done either on plate rolls—machines that incorporate three or four rollers to form curved shapes—or “bumped” with a radius die on a press brake. Both methods have their strengths and weaknesses. Everything else being equal (same plate thickness, same plate radius, same grade of steel), press brakes can usually “nose” the plate closer to the end of the plate thereby minimizing or eliminating any flatness. Plate rolls can also prebend plate to minimize straight tails but usually not as well as press brakes. At times plate is nosed in a press brake and then rolled in a plate roll to get the best results.
Plate rolls can usually roll 360 degree cylinders better than press brakes can. The ends of the curved cylinders can end up be obstructed by the press brake die or by the machine itself. Plate rolls can roll a cylinder through 360 degrees. This process is sometimes used to “round up” an out-of-round cylinder.
For example, plate rolling is the best method to form a 2-1/2 inch thick plate 40 inches long to a 2 foot 7 inch outside diameter full cylinder.
After being rolled, this cylinder was sent to a machine shop where additional fabrication created a part that is the main hub of a custom milling machine. The quality of the rolling contributed to the success of the machining.