A plate rolling machine is a machine that will roll different kinds of metal sheet into a round or conical shape. The flat metal plate is placed in the machine on either side and "pre-bent" on the same side. The side rolls do the work of bending. The pinching roll holds the plate.
The three-roll variable pitch works by having all three rolls able to move and tilt. The top roll moves in the vertical plane and the side rolls move on the horizontal plane. When rolling, the top roll presses the metal plate between the two side rolls. The advantage of having the variable three roll is the ability to roll many thicknesses and diameters of cylinders.
The side-rolls are what produce the mechanical advantage. With the side rolls all the way open, one has the maximum mechanical advantage. With the side rolls all the way in, you have the least mechanical advantage.
