# Ring rolling mill

Schematic representation of a ring rolling mill (top view)
Ring rolling mill of the Bochumer Verein with an open frame

A ring rolling mill is a special rolling mill in which ring blanks are rolled to their final dimensions . Ring blanks are obtained z. B. by forging and punching a steel block in a press.

## Products

Rolled rings are z. B. required as wheel tires or as bearing shells of large roller bearings and can have a diameter of a few tens of centimeters up to nine meters. Other important products that are manufactured by ring rolling are gear wheels and bevel gears or their preliminary products.

## functionality

In a modern radial-axial (ring) rolling mill ( RAW , colloquially ring rolling machine ), the curved ring surfaces and the end surfaces of a ring are rolled by means of two separate roll gaps: The ring wall thickness is between a driven main roller (formerly "plate roller") that acts on the outside of the ring. as well as a mandrel roll acting on the inside of the ring ("radial roll gap"). The ring height is rolled in the opposite axial roll gap. The reduction in wall thickness and ring height results in a tangential flow of material, which increases the ring diameter due to the constant volume (neglecting the temperature-related shrinkage). The axial roll gap consists of two 'conical' rolls. To reduce the height of the ring, the upper axial roller is advanced against the lower axial roller. Colloquially, the axial rollers are also referred to as tapered rollers. Both axial rollers are arranged in the axial stand. In order to avoid the ring diameter increase, the axial frame is positioned radially along the machine's longitudinal axis. The longitudinal axis of the machine is formed by the axis of the main and mandrel roller and the longitudinal axis of the axial rollers.

Manufacturing steps for ring production

At the start of rolling, the ring blank is placed in the rolling mill and the rolling mill frame, which essentially only supports the rolling mandrel, is closed. The centering of the ring in the rolling mill frame can be controlled by the speeds of the two tapered rollers and the tension of two centering rollers. By using profiled main and mandrel rolls, the outer and / or inner ring surface can be profiled. Examples are wheel tires, ring flanges or structural rings. Recently, it has also been possible to roll axially profiled rings by using profiled axial rollers.

## history

Rings - especially wheel tires for the emerging railways - were rolled at the beginning of industrialization with drum mills ( head rolling mills ) with which the ring thickness and width as well as the exact circular shape had to be set in several process steps. The simplest form of such a drum rolling mill is a duo rolling mill in which the rolls protrude from the stand on one side so that the ring can be inserted between the rolls. In 1889, James Munton developed the current basic shape of the ring rolling mill.

## swell

• Patent US416798 : Process of rolling tires. Registered August 5, 1889 , published December 10, 1889 , inventor: James Munton.
• Patent DE54323A : Wheel tire rolling mill . Registered December 9, 1889 , inventor: J. Munton.
• Patent DE1752887C : four-roll ring rolling mill. Registered on July 31, 1968 , published on June 6, 1974 , applicant: J. Banning AG, inventor: Anton Matzke, Eugen Wieting.
• Patent DE2222606A : Ring rolling mill. Registered on May 9, 1972 , published on November 29, 1973 , applicant: Rheinstahl AG, inventors: Josef Jeuken, Konrad Meyer, Gustav Vieregge.
• Patent DE2222608C2 : Ring rolling mill. Registered on May 9, 1972 , published on July 5, 1984 , applicant: Thyssen Industrie AG, inventor: Gustav Vieregge.
• Article "Walzwerk", section "Kopfwalzwerk" in Meyers Großes Konversations-Lexikon, 1905 edition online