Mannesmann Aktiengesellschaft

Karl H Hausler

Gunther Voswinckel

Horst Stinnertz

Peter Kalkenings

Jurgen Pietsch

Johann H Rohde

Jochen Vochsen

Burkhart Schifferings

Gheorghe Arnautu

Karl-Helmut Wengenroth

A process for drawing stretched metal workpieces, especially tubes, for the purpose of cross-sectional reduction in more than one drawing step using at least two sequential drawing aggregates. The aggregates grip the workpiece on the outer periphery, with two alternately-moved clamping carriages, which draw the workpiece continuously through respective drawing rings associated with the respective aggregates and arranged in respective drawing-ring holders. The drawing aggregates can be driven independently of one another in a power-regulated and/or moment-regulated manner. Furthermore, during the drawing process, a defined prestress force, which prevents deflection of the workpieces from a straight line, is maintained at all times in the section of the workpiece located between the drawing aggregates.

Process and device for straight-drawing long drawing material in

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

A roll mandrel monitoring device in cold pilger mills with a coil which surrounds the rolled tube concentrically and is arranged on the delivery side after the rolling mill for detecting longitudinal movement of a coil core which is fastened inside the tube to a bar extending between the mandrel and coil coaxially to the tube. In order to achieve faster reaction times and accordingly to stop the rolling mill when the mandrel breaks, the bar is connected with the mandrel rod holding the mandrel so as to penetrate the mandrel concentrically and is constructed in the region of the mandrel as a tension bar which can be pretensioned against the end of the mandrel on the delivery side with the intermediary of an energy accumulator.

Roll mandrel monitoring arrangement in cold pilger mills

A method of producing seamless pipes by carrying out a plug rolling procedure includes expanding and stretching a hollow ingot into a bloom by carrying out at least two consecutive passes in a roll stand having a box-groove and by using a stationary plug supported by a rod. The bloom is pulled after each pass from the rod in a direction opposite the rolling direction. The bloom is turned after each pass by 90.degree. C. about a longitudinal axis thereof and the plug is exchanged after each pass. The method further includes the step of adjusting in one of the passes a wall thickness of the bloom in a wall portion of the bloom at the groove bottom by changing the roll distance in order to thin-stretching the wall portion such that the wall thickness of the finish-rolled bloom is uniform over the circumference thereof.

Method of producing seamless pipes utilizing a plug rolling procedure

A method of longitudinal rolling of seamless pipes in a continuous rolling procedure on an internal tool in a multiple-stand rolling train, wherein the rolls of successive rolling stands are mounted off set relative to each other. In accordance with the present invention, in a first of only two successive rolling passes, a roll thickness reduction is produced with opened roll groove sides in the roll groove bottom which reduction corresponds to or is slightly greater than the roll thickness of the finished pipe. In the second rolling pass, the side portion of the first rolling pass is reduced in the direction of the width to the wall thickness of the finished pipe in the roll groove bottom of the second rolling pass. By simultaneously applying a controlled tensile force on the pipe between the two rolling passes, the increase of the circumference of the pipe due to spreading is reduced by stretching the pipe in the direction of its longitudinal axis without reducing the wall thickness or with only a slight reduction of the wall thickness.

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Korschenbroich, Germany

Karl H Hausler