Ring Rolling,Ring Rolling,Ring Rolling
RING ROLLING is a versatile metal-forming process for manufacturing seamless annular forgings that are accurately
dimensioned and have circumferential grain flow. Ring rolling usually requires less input material than alternative forging
methods, and it is applicable to production in any quantity.
In ring rolling, a heated doughnut-shaped blank, preformed on a press or forging hammer, is placed over a mandrel of
slightly smaller diameter than the hole in the blank. The roll gap between the mandrel (undriven) and a larger-diameter
driven main roll is progressively reduced. Friction between the main roll and the ring causes the ring to rotate, and the
ring in turn rotates the bearing-mounted mandrel. As the radial cross section of the ring decreases, circumferential
extrusion occurs in the direction of ring rotation, and the ring diameter grows. The work rolls may be plain, producing
uniformly rectangular ring cross sections, or may have grooves or flanges to produce contoured ring cross sections. Ring
height is controlled either by main roll shape or by the use of axial rolls set diametrically across the ring from the mandrel
and main roll pass.

Product and Application
Annular components can be ring rolled from any forgeable material. The configuration can range from very flat washershaped
rings to long sleeve-type rings (Fig. 1). Typical materials include carbon and low-alloy steels, copper, brass,
aluminum and titanium alloys, and high-strength nickel- and cobalt-base alloys, which are very difficult to form.
Applications for seamless rolled rings include antifriction bearing races, gear rims, slewing rings, railroad wheel bearings,
commutator rings, rotating and nonrotating rings for jet engines and other aerospace applications, nuclear reactor
components, bevel ring gears, and flanges of all kinds (including weld-neck flanges), sheaves, wheels, valve bodies, foodprocessing
dies, and chain master links.

Sizes. About 90% of all rolled rings have outside diameters in the range from 240 to 980 mm (9.5 to 38.6 in.), heights
(lengths) ranging from 70 to 210 mm (2.75 to 8.25 in.), and wall thicknesses between 16 and 48 mm (0.63 and 1.9 in.). A
significant number of rings, however, are rolled outside the above parameters, and it is not unusual to find outside
diameters ranging from 75 mm to 8 m (3 in. to 26.25 ft), heights from 15 mm to 2 m (0.6 in. to 6.5 ft), and weights from
0.4 to 82,000 kg (0.9 to 181,000 lb).
Shapes (Contours). Figure 2 shows a range of typical contoured/shaped cross sections that can be produced by ring
rolling. In some cases, it is more economical and more practical to roll contoured rings as 2 in 1 multiples that are then
slit. The two identical components are usually mirrored so as to place the thinnest wall section at the midheight of the
rolled ring for ease of parting. Because the ring is then symmetrical about the line of midheight, such a ring can often be
rolled from a simple blank, and it behaves more predictably during rolling than an asymmetrical ring would if rolled
singly.

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