Mannesmann Aktiengesellschaft

Jurgen Pietsch

Ettore Cernuschi

Karl H Hausler

Gerhard Kulessa

Gunther Voswinckel

Thomas Leisten

Gheorghe Arnautu

Karl-Helmut Wengenroth

Walter Randerath

Ingo Baade

Frank Salomon

A process for producing a hollow billet for producing tubing for antifriction bearings includes massively reducing a bloom in a three-roll rotary piercing mill and subsequently piercing the reduced bloom in a three-roll rotary piercing mill. The reducing and piercing may be performed in one-pass through the three-roll rotary piercing mill. The reducing and piercing steps may also be performed in separate passes through the same mill or through two separate mills.

Process for the production of seamless tubes

A method of calibrating and orienting forming rollers of an Assel-type rolling mill, and more particularly, of calibrating an Assel mill for rolling thin-walled tubes of pre-pierced hollow bodies about a mandrel, using at least three generally conical rollers that are circumferentially spaced about the mandrel. The orientation of each forming roller is adjusted so as to position the roller inclination relative to the mandrel axis of roll by an expansion angle .alpha. of approximately 7.degree. to 30.degree.. Each forming roller is also adjustably oriented so that its smoothing part relative to the mandrel axis of roll defines a transport angle .gamma. of approximately 7.degree. to 17.degree.. In further accordance with this invention, each forming roller is configured so as to have an opening angle .beta. of approximately 4.degree. to 15.degree..

Method for calibration of assel rollers

The invention relates to a process for reducing the outside diameter and wall thickness by rolling a cylindrical hollow ingot the front part of which is fed into an Assel rolling mill, in which connection, in front of the Assel rolling mill as seen in the direction of feed, a device is provided for reducing the diameter and/or wall thickness of the rear end part of the hollow ingot threaded onto a mandrel rod. In this process, the prereduction rolls are slowly and continuously pressed against the ingot at a predetermined point near the end of the ingot to produce a conically reduced end portion.

Process for the rolling of hallow ingots on a assel rolling mill

Growing community of inventors

Monchengladbach, Germany

Jurgen Pietsch