Mannesmann Aktiengesellschaft

Horst Biller

Manfred Bellmann

Wilhelm Nickel

Rolf Kuemmerling

Gerd Pfeiffer

Alfred Lampe

Hermann-Josef Frentzen

Karl Oberem

A method of manufacturing seamless pipes having medium-thick or thin walls from an elongated hollow body of limited length which is reshaped by rolling to the desired final dimension, as well as a rolling apparatus for the carrying out of the method. This method of manufacturing seamless pipes having medium-thick or thin walls from an elongated hollow body is characterized by the fact that, with only one rolling pass the diameter of the hollow body is significantly reduced and by using an inner tool the inner surface is smoothed with only a slight change in wall thickness. Further, this method allows for the rolling of the axis of the hollow body to align with the axis of rolling. The rolling apparatus includes an inner tool which cooperates with two rolls to reduce the diameter of the pipe to a desired final dimension, the two rolls each having an inlet part, a feed part, a reducing part inclined at an angle within the range of more than 2.degree. and up to 10.degree. and adjoining same, with a transition in the form of a circular arc, and a substantially cylindrical reeler with a difference angle to the working part of the inner tool within the range of 0.degree. to 1.degree., followed by an outlet part.

Method and apparatus for manufacturing medium-walled and thin-walled

Seamless tubing and pipes are made from solid rounds with a diameter not exceeding 0.8 of the diameter of the tubing or pipe to be made; the method includes the steps of piercing the solid with a mandrel such that a conical widening angle at the end of piercing has a particular value; a smoothing step is provided downstream from the piercing also with a particular cone angle; and between the piercing and the smoothing of the now pierced hollow is widened under reduction of the wall thickness at a conical angle of widening that is larger (blunter) than the widening angle of piercing and the particular cone angle.

Making seamless pipes, over 200 mm in diameter

It was discovered that a rolling mandrel holding a hollow which is rolled in a multistrand mill should be advanced in a particular manner that relates to the stretching the hollow undergoes in the first and second stand, as well as to the speed of the unrolled hollow. A velocity profile has been developed accordingly.

Operating a rolling mill working on seamless tubing

Growing community of inventors

Mulheim, Germany

Horst Biller