Abstract: Ingots hot from rolling are pierced to form a hollow ingot by means of an internal tool of a press or skew-rolling line, and are subsequently elongated to form a tubular bloom by a stretching unit provided with a mandrel rod, and are finally finish-rolled. When inserting or withdrawing the internal tool into or out of the hollow ingot or the mandrel rod into or out of the tubular bloom, inert gas is introduced into the freed interior space in order to prevent scaling of the interior wall of the tubular bloom.

Abstract: The invention concerns a gear unit for driving the rolls of a roll train with a number of consecutively arranged roll stands. This gear unit has planetary gear sets at at least one output shaft, which are located one behind the other at short distances. Due to a crosshead provided in accordance with the invention, the output shaft of each planetary gear set is relieved of bearing forces and the torques of the gears, such that it can have a small diameter, which in turn permits a building up of the planetary gear set, such that the operating torque and the operating r.p.m.'s of the planetary gear sets can be considerably higher than in the familiar construction types.

Abstract: In a transmission for driving the rolls of a rolling line having a number of rolling stands disposed one after another, a respective planetary transmission stage is provided at several output shaft (20) and forms the output rotational speed from a basic rotational speed and an additional rotational speed. The gear wheels (2,23) of the gear wheel transmission trains transmitting the basic and additional rotational speeds are mounted on stationary bearing bushes (3, 26) which project into the hub regions of the gear wheels (2, 23) and are secured in bores or on flange facings of the load-bearing walls (5, 6) of the transmission housing (1). Only one of the gear wheel transmision trains is disposed between the load-bearing walls of the transmision housing, while the other is disposed on the outside stands. This permits the transmission to be of lighter construction and allows greater gear ratios in the gear wheel transmission trains and a smaller distance between the output shafts (20).

Abstract: A method and apparatus for transverse, preferably skew, rolling seamless tube blanks, is provided wherein said seamless tube blanks are rolled down by a mandrel rod lying in their longitudinal bore or are rolled onto a mandrel rod at the delivery end. During transverse rolling each tube blank is subjected to a predetermined, controllable torque exerted by the mandrel rod in order to eliminate substantially the formation of pockets in the region of the sizing pass during transverse rolling.

Abstract: This invention concerns a process and an arrangement for the production of seamless tube. An ingot heated to the rolling temperature is pierced in a skew-rolling stand to form a hollow ingot, is later stretched into a tube bloom and is rolled out into a finished tube. In order to improve this familiar process, it is proposed to conduct the stretching immediately after the piercing in the same heat as the latter, in which case the rolled goods is stretched in the same skew-rolling stand, but with a passage direction that is opposite to that of piercing. An arrangement with which this process according to the invention can be implemented is also proposed.

Abstract: A rolling line for the stretch-reducing of tubes, has a plurality of rolling stands which are arranged closely one after the other. These rolling stands are driven by a group drive, whereby the rolling stands, or at least a part thereof, are divided into groups, the groups being defined between directly acting drive shafts (111). The stand locations lying between these drive shafts (111) are driven by way of differential gear stages (112), each combining two rotational speeds which are derived by way of gear wheel trains (113-116, 117-120) from the drive shafts (111).

Abstract: In a rolling mill plant for the manufacture of seamless tubes, a piercing mill (2), a planetary skew rolling mill (15) and a sizing or stretch-reducing rolling mill (18) are arranged one after the other. In order to improve the output and the quality of the products of plant of this kind, it is proposed not to withdraw the shaft rods (11) used during the piercing operation in the mill (2), but also to use them as internal tools in the planetary skew rolling mill (15). The shaft rods can then remain at the entry end upstream of the planetary skew rolling mill (15) from where they can be returned to the piercing mill (2). Alternatively (FIGS. 2 and 4) they can also pass through the planetary skew rolling mill and be returned from the delivery end thereof to the piercing mill. The insertion, hitherto required, of rods into the hollow ingots before entering the planetary skew rolling mill is not required. The heavy scaling of the surface of the bore in the hollow ingot thereby occurring is avoided.

Abstract: A rolling mill plant has a planetary skew rolling mill and a reducing or sizing rolling line disposed at a short distance therebeyond for the purpose of manufacturing tubes. In order to avoid axial stressing of the work material between the planetary skew rolling mill and the reducing or sizing rolling line when the work material is simultaneously located in both of them, a tension and compression measuring device is disposed in the region of the reducing or sizing rolling line for the purpose of corresponding regulation of the latter's drive motor. A torque measuring device is disposed between the mounting of the mandrel rod of the planetary skew rolling mill in order to be able to detect torque stresses in the work material which are then eliminated in dependence upon the measured values of the torque measuring device by corresponding regulation of the rotational speed of the rolls and of the rotor of the planetary skew rolling mill.

Abstract: A plant for the manufacture of seamless tubes is provided having successively a roughing unit and a finishing push bench unit which finish push bench unit includes all sizing passes which are simultaneously in operation with the finishing passes on a tube at the end of the elongation operation.

Abstract: In a method of rolling tubes in a stretch-reducing rolling mill having a group drive in which the elongation, and therefore the tension is increased by increasing the speed of an auxiliary drive motor relative to that of a main drive motor, the length of the trailing "thickened end", which must be rejected as scrap, is reduced by increasing the elongation from the point in time at which the start of the trailing end portion of the tube reaches the last stand. This trailing end portion is that portion which receives a larger wall thickness than the central portion of the tube as a result of the reduced tension exerted in the trailing end portion of prior art practices. The start of this trailing end portion can be predicted from experience or by rolling a sample tube without subjecting its trailing end portion to the said increased elongation and measuring the wall thickness at the trailing end portion of the sample tube.

Abstract: In a multi-stand stretch-reducing tube-rolling mill, the stands at the entry end forming a first group are driven from a main motor and an auxiliary motor and the remaining stands forming a second group are driven from the main motor and a separate auxiliary motor, the corresponding rotational speeds derived from the main motor and one or other of the auxiliary motors being added by means of a planetary gear in a summing transmission. A single stand between the two groups can be driven from the main motor only. The separate auxiliary motor at the entry end enables control over the tube elongation (or compression) to be effected over a shorter tube length, and thereby more accurately.

Abstract: An adjustment device is provided for regulating the total degree of drawing in a multi-stand stretch reduction rolling mill for the stretch reduction of tube having a digital unit which calculates intermittently the desired or theoretical stretchings (.lambda. theor.) from the entering and exiting wall thicknesses (S.sub.o, S) and the external diameters (D.sub.o,D) of both the actual entering and desired finished tube sections and continuously the actual stretchings (.lambda. act.) from the entrance and exit speeds (V.sub.o,V) of the tube, and a regulator adjusting the roll r.p.m.'s as a function of the differences in theoretical and actual stretchings (.DELTA..lambda.).

Abstract: A rolling mill roll and method of rolling tubes is provided in which the roll has an annular concave working surface in the outer periphery, said surface having a central annular concave portion of a preselected arc and a pair of side edge annular concave portions on each side of said central portion, said side edge portions having an arc of greater radius than the central portion and thus of lesser curvature than the central portion.

Abstract: A method for the manufacture of longitudinal-seam welded tubes of substantial thickness is provided in which a strip of steel is curled to form a longitudinally slit tube and the slit is welded in a longitudinal-seam welding plant and in which the seam-welded tube thus produced is fed into a tandem arranged reducing mill, in which it is rolled in the longitudinal direction of the tube between the stands of the reducing mill without being subjected to longitudinal tension while at the same time its external diameter is reduced. A longitudinal seam-welded tube made by the method is claimed.

Abstract: A process and mill for stretch reduction rolling of tubes is provided having individually driven roll stands, said roll strands being driven so as to impart a maximum traction force, limited only by the transferability of frictional forces between roll and tube, on the tube in all the passes that grip said tube, at least in the passes at the entry end of the mill.

Abstract: An improved rolling mill capable of both stretch reducing tubes having relatively small external diameters and of reducing tubes having relatively large external diameters is provided having a plurality of successive roller stands some stands having small roll diameters and other stands having large roll diameters, the said other stands having large roll diameters being arranged to follow, in the direction of rolling, the said some stands having small roll diameters so that said other stands are at the exit end of the rolling mill.

Abstract: A stretch-reducing rolling mill is provided for selectively producing tubes of circular or angular configuration, such as a square, is provided in the form of a plurality of driven roll stands arranged in two groups, one at the entrance end being equipped with three roller stands and a second at the rear or exit end being arranged to use either three or four roller stands optionally, said first group of stands being driven by a common drive train separate and independent of the drive for the second group.