The "four-roll" is a technique used in various fields, including engineering and manufacturing, to shape materials. It involves passing a metal sheet through four rollers, which apply pressure and gradually bend the material into a desired shape. This method is efficient for producing cylindrical or conical forms. In the context of metalworking, the four-roll system offers advantages over traditional three-roll methods. It provides better control over the curvature and thickness of the material, resulting in higher precision. This technique is commonly used in industries such as automotive, aerospace, and construction for creating components like pipes and tanks.