Abstract: A method for producing hot-rolled, seamless pipes having at least one wall thickening which can be arranged at any positions over the length of the pipe, wherein by means of a multiple-stand mandrel bar rolling mill, the rolls roll a hollow shell on a mandrel bar as an inner tool to a required nominal wall thickness and produce at specified positions over the length of the pipe a required wall thickening on the outer side of the pipe by opening the rolls in the rolling stands. The thickened wall is produced and finish-rolled by two rolling stands that are consecutive as seen in the rolling direction, in which the deviations of the finished contour of the thickening from an ideal circular cross-section are minimised, wherein the rolling stands located upstream are likewise opened as to avoid any contact of the rolls of these rolling stands with the previously produced thickening.

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: A piercing mandrel for piercing heated round blocks of metal for the production of seamless pipes, having a piercing mandrel nose and a piercing mandrel main body which can be connected to a mandrel bar. The outer diameter of the piercing mandrel nose is formed in a conically tapering manner in the longitudinal direction towards the piercing mandrel main body in order to increase the durability of the piercing mandrel when used for piercing round blocks of metal, in particular higher-alloyed steel materials which are difficult to work, by means of skew rolling providing a qualitative improvement of the inner surface of the pierced round block and reducing tool costs.

Abstract: A method for producing hot-rolled, seamless pipes having at least one wall thickening which can be arranged at any positions over the length of the pipe, wherein by means of a multiple-stand mandrel bar rolling mill, the rolls roll a hollow shell on a mandrel bar as an inner tool to a required nominal wall thickness and produce at specified positions over the length of the pipe a required wall thickening on the outer side of the pipe by opening the rolls in the rolling stands. The thickened wall is produced and finish-rolled by two rolling stands that are consecutive as seen in the rolling direction, in which the deviations of the finished contour of the thickening from an ideal circular cross-section are minimised, wherein the rolling stands located upstream are likewise opened as to avoid any contact of the rolls of these rolling stands with the previously produced thickening.

Abstract: A piercing mandrel for piercing heated round blocks of metal for the production of seamless pipes, having a piercing mandrel nose and a piercing mandrel main body which can be connected to a mandrel bar. The outer diameter of the piercing mandrel nose is formed in a conically tapering manner in the longitudinal direction towards the piercing mandrel main body in order to increase the durability of the piercing mandrel when used for piercing round blocks of metal, in particular higher-alloyed steel materials which are difficult to work, by means of skew rolling providing a qualitative improvement of the inner surface of the pierced round block and reducing tool costs.

Abstract: In a method for producing seamless pipes, a hot hollow block created previously in a piercing mill is stretched by means of a continuous rolling mill on a mandrel bar to form a parent pipe and the parent pipe is fed directly to a stretch reducing mill or sizing mill as a finishing mill, while forgoing an extracting mill and a reheating furnace, and is rolled there to the required final pipe diameter. The hollow block is pre-dimensioned in its length in such a manner that only a single length is produced as the required parent pipe length during the stretching in the continuous rolling mill and the parent pipe is pulled off of the mandrel rod by the finishing rolling during the subsequent finishing rolling, wherein the rolling is performed using rolling mill components that are designed in the dimensions thereof for handling single lengths.

Abstract: A device for the optimized circulation of mandrels includes a presentation and/or cooling table for mandrel rods, a lubricating station for the mandrel rods, optionally an additional drying station for the lubricant applied to the mandrels, and associated roller conveyors. An additional secondary rod circulation of is arranged upstream of the standard rod circulation and includes two redundantly operating transfer tables connected to the presentation and/or cooling table by a third roller conveyor or the first roller conveyor for the discharge of no longer needed rods from the standard rod circulation. The third roller conveyor either forms the continuation of the first roller conveyor or is arranged parallel thereto with an offset. A fourth roller conveyor for accommodating mandrel rods or passing mandrel rods intermittently into the standard circulation via an intermediate buffer is arranged on the opposite side of the transfer tables parallel to the first roller conveyor.

Abstract: The invention relates to a method for producing seamless tubes from metal, particularly from steel, wherein a previously produced hot hollow block is stretched by means of a three-roll bar rolling mill on a mandrel to form a parent tube and, before running into the bar rolling mill, the hollow block is provided with a rolling step that makes the diameter more uniform by means of an upstream stand. It is in this case provided that the rolls of the upstream stand are moved apart and together to the same extent as the deforming stands of the bar rolling mill, wherein the calibrating base radius of the rolls of the upstream stand extends over 60° and this is followed by a flank radius with a tangential transition which is dimensioned such that even with the maximum setting of the rolls in the region of the flank there is virtually no diameter reduction of the largest hollow block diameter to be expected.

Abstract: In a method for producing seamless pipes, a hot hollow block created previously in a piercing mill is stretched by means of a continuous rolling mill on a mandrel bar to form a parent pipe and the parent pipe is fed directly to a stretch reducing mill or sizing mill as a finishing mill, while forgoing an extracting mill and a reheating furnace, and is rolled there to the required final pipe diameter. The hollow block is pre-dimensioned in its length in such a manner that only a single length is produced as the required parent pipe length during the stretching in the continuous rolling mill and the parent pipe is pulled off of the mandrel rod by the finishing rolling during the subsequent finishing rolling, wherein the rolling is performed using rolling mill components that are designed in the dimensions thereof for handling single lengths.

Abstract: The invention relates to an apparatus for making a seamless hollow body (10) from a solid round block (7) of steel with a diameter <95% of the diameter of the solid round block by means of a two-roll cross-rolling mill with a piercing mandrel (3) held between the inclined roll (1) and including a piercer (5) and at least one smoothing part (4) using pass-closing guides, or by means of a three-roll cross rolling mill with a piercing mandrel held between the inclined rolls and including a piercer and at least one smoothing part, wherein the distance of the rolls is adjusted in a particular manner at the narrowest cross-section (2) in relation to the diameter of the used round block, and the position of the piercing mandrel is adjusted in relation to the narrowest cross-section of the rollers.

Abstract: A device for the optimized circulation of mandrels includes a presentation and/or cooling table for mandrel rods, a lubricating station for the mandrel rods, optionally an additional drying station for the lubricant applied to the mandrels, and associated roller conveyors. An additional secondary rod circulation of is arranged upstream of the standard rod circulation and includes two redundantly operating transfer tables connected to the presentation and/or cooling table by a third roller conveyor or the first roller conveyor for the discharge of no longer needed rods from the standard rod circulation. The third roller conveyor either forms the continuation of the first roller conveyor or is arranged parallel thereto with an offset. A fourth roller conveyor for accommodating mandrel rods or passing mandrel rods intermittently into the standard circulation via an intermediate buffer is arranged on the opposite side of the transfer tables parallel to the first roller conveyor.

Abstract: The invention relates to a method for producing seamless tubes from metal, particularly from steel, wherein a previously produced hot hollow block is stretched by means of a three-roll bar rolling mill on a mandrel to form a parent tube and, before running into the bar rolling mill, the hollow block is provided with a rolling step that makes the diameter more uniform by means of an upstream stand. It is in this case provided that the rolls of the upstream stand are moved apart and together to the same extent as the deforming stands of the bar rolling mill, wherein the calibrating base radius of the rolls of the upstream stand extends over 60° and this is followed by a flank radius with a tangential transition which is dimensioned such that even with the maximum setting of the rolls in the region of the flank there is virtually no diameter reduction of the largest hollow block diameter to be expected.

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: The invention relates to a forging mandrel for hot-forging tubular workpieces of metal, said mandrel comprising a mandrel body and a mandrel bar, in which forging mandrel the mandrel body is composed of a heat-resistant material. The forging mandrel according to the invention is embodied here in such a way that the mandrel body is provided, at least in the work zone, with a layer which reduces the dissipation of heat into the mandrel body during the forging process and adheres firmly to the mandrel body, wherein the layer has a lower thermal conductivity than the material of the mandrel body and has a thickness of at least 50 ?m.

Abstract: The invention relates to an apparatus for making a seamless hollow body (10) from a solid round block (7) of steel with a diameter <95% of the diameter of the solid round block by means of a two-roll cross-rolling mill with a piercing mandrel (3) held between the inclined roll (1) and including a piercer (5) and at least one smoothing part (4) using pass-closing guides, or by means of a three-roll cross rolling mill with a piercing mandrel held between the inclined rolls and including a piercer and at least one smoothing part, wherein the distance of the rolls is adjusted in a particular manner at the narrowest cross-section (2) in relation to the diameter of the used round block, and the position of the piercing mandrel is adjusted in relation to the narrowest cross-section of the rollers.

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.