ringrolling

Ring rolling is a metal forming process used to manufacture seamless hollow rings with precise inner and outer diameters and uniform cross-sections. It transforms a blank, such as a circular disk or cup-shaped piece, into a ring by passing it between grooved rolls while supported by a mandrel that defines the inner diameter.

The process typically involves a ring rolling mill with two or more grooved rolls arranged to form and shape the blank. The blank is placed around a mandrel and between the rolls, which rotate and apply plastic deformation. As the rolls advance, the blank flows radially and circumferentially, increasing its outer diameter while reducing thickness. The inner diameter is controlled by the mandrel, producing a finished ring with tight tolerances. Ring rolling can be performed hot or cold, with hot ring rolling common for larger rings or harder materials to avoid cracking, and cold ring rolling used for small-diameter rings requiring high dimensional accuracy.

Variations of the method include closed-die and open-die configurations, and different mill arrangements such as two-roll or three-roll setups. Materials commonly processed include steel, aluminum, copper alloys, titanium, and other metals used for bearing rings, gears, turbine components, and structural rings. Ring rolling offers advantages such as a favorable grain structure, high strength, dimensional precision, good surface finish, and suitability for producing large, complex rings without seams.

Quality control typically encompasses measurements of inner and outer diameters, wall thickness, roundness, and surface finish, along with non-destructive testing for critical applications.