Abstract: A rolling rod configured as an inner tool in the production of seamless hollow bodies, such as seamless pipes. The rolling rod has a nitrided surface layer and may consist of a heat-resistant steel material having a chromium equivalent calculated by a formula, as well as has a minimum hardness, yield point and tensile strength. A seamlessly hot-rolled, metallic hollow body is produced by a stretch-forming procedure in a multiple-stand rolling mill via the rolling rod which is threaded into the hollow block. Prior to threading the rolling rod into the hollow block, the rolling rod is provided with a liquid lubricant and is subsequently dried. The rolling rod is threaded in with a clearance with respect to the inner diameter of the hollow block. Prior to threading-in the rod, the hollow block may have an average temperature of at least 1000° C., with the rod having a determined speed.

Abstract: In a method of making a seamless hot-finished steel pipe a billet heated to a shaping temperature is pierced by a first shaping to a thick-walled hollow ingot which subsequently undergoes a radial forging process using an internal tool inserted in the hollow ingot and at least two forging jaws of a forging machine. The forging jaws act on the outer surface area of the hollow ingot, wherein the hollow ingot is turned and axially advanced in a clocked manner in the idle stroke phase of the forging jaws.

Abstract: A method and a device for producing a hollow body from solid round steel that has been heated to shaping temperature by piercing in an inclined rolling mill using pass-closing guide elements. For this purpose, prior to the commencement of piercing, the clear distance between the pass-closing guide elements is reduced in comparison to that of the stationary rolling phase and, after initial rolling, the distance is adjusted to the customary value for the stationary phase. The changes in distance are effected automatically through the balancing of the forces acting on the pass-closing guide elements during the shaping of the round steel and the closing forces which keep the pass opening dimension small.

Abstract: 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.

Abstract: 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.

Abstract: The press tool as disclosed is provided for making tubes or pipes at a diameter of 600 millimeters or more and a diameter-to-wall-thickness ratio of 13 or more. In order to permit employment of the tool for a relatively wide range of dimensions without requiring extensive retooling, it is suggested that the tool is comprised of a stationary centerpiece and side pieces, which are hinged to the centerpiece and held in position by spacer bars acting as adjustable cams.

Abstract: Diagonal rolls for stretching hollows are of a truncated-cone-like configuration, each with two shoulders and a recess in between, for cooperation with a cylindrical mandrel rod in order to obtain a two-stages-in-one reduction in wall thickness; the shoulders merge in smoothing surfaces.