Abstract: An automatically adjusting auto gauge system comprises a servo motor that provides rotational motion; at least one of a gearbox and linear actuator driven by the one or more servo motors to transfer the rotational motor of the servo motor to linear motion; a group of roll former passes, each including a cam arm, an eccentric cam, a push rod, a top set of roll tooling, a bottom set of roll tooling; a bar operably coupled to the gearbox and the cam arms of the group of roll former passes, the bar driven by the gearbox to impart linear motion to the cam arms, which in turn imparts rotational motion to each eccentric cam, which in turn imparts linear motion, raising or lowering the top set of roll tooling via the push rod, adjusting a gap between the top and bottom sets of roll tooling.

Abstract: Provided herein is a high-strength stainless steel seamless pipe for oil country tubular goods. The high-strength stainless steel seamless pipe having a yield strength of 862 MPa or more contains, in mass %, C:0.05% or less, Si: 0.5% or less, Mn: 0.15 to 1.0%, P: 0.030% or less, S: 0.005% or less, Cr: 14.5 to 17.5%, Ni: 3.0 to 6.0%, Mo: 2.7 to 5.0%, Cu: 0.3 to 4.0%, W: 0.1 to 2.5%, V: 0.02 to 0.20%, Al: 0.10% or less, N: 0.15% or less, B: 0.0005 to 0.0100%, and the balance Fe and unavoidable impurities, and in which the composition satisfies specific formulas. The stainless steel pipe has more than 45% martensite phase, 10 to 45% ferrite phase, and 30% or less retained austenite phase. The ferrite grains have a maximum crystal grain size of 500 ?m or less.

Abstract: The invention is intended to provide a high-strength stainless steel seamless pipe for oil country tubular goods having high strength with a yield strength of 862 MPa (125 ksi) or more, excellent low-temperature toughness, and excellent corrosion resistance. The invention is also intended to provide a method for manufacturing such a high-strength stainless steel seamless pipe. The high-strength stainless steel seamless pipe has a microstructure that is at least 45% tempered martensite phase, 20 to 40% ferrite phase, and more than 10% and 25% or less retained austenite phase by volume. The high-strength stainless steel seamless pipe has a yield strength of 862 MPa or more, and a maximum crystal grain diameter of 500 ?m or less for ferrite crystal grains when crystal grains with a crystal orientation difference of within 15° are defined as the same crystal grains.

Abstract: A rolling plant (R) for rolling tubes having a multi-stand rolling mill (5) with two or more rolls, in order to implement a controlled speed mandrel rolling process, comprises a hooking and releasing device (61) which is arranged in the inlet area of the rolling mill (5) to cooperate with the rear tang of the mandrel (31) and a hooking and releasing device (71) which is arranged in the outlet area of the rolling mill (5) to cooperate with the front tang of the mandrel (31) in coordinated manner with the first hooking and releasing device (61).

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 tube expanding drum machine, including a support frame, at least one drum rotatably supported in said frame, rotation means of the drum about its axis, a flexible pipe-expanding shaft wound on the drum and having a first end fixed to the drum, an expanding mandrel or a shaped ogive, connected to the second end of the flexible pipe-expanding shaft, suitable for widening the diameter of a pipe by winding or unwinding the flexible pipe-expanding shaft onto or from the drum inside the pipe itself. The machine includes a lubrication duct of the inner surface of the pipe during the pipe expansion foreseen inside the flexible shaft.

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: A rolling plant (R) for rolling tubes having a multi-stand rolling mill (5) with two or more rolls, in order to implement a controlled speed mandrel rolling process, comprises a hooking and releasing device (61) which is arranged in the inlet area of the rolling mill (5) to cooperate with the rear tang of the mandrel (31) and a hooking and releasing device (71) which is arranged in the outlet area of the rolling mill (5) to cooperate with the front tang of the mandrel (31) in coordinated manner with the first hooking and releasing device (61).

Abstract: A machine is disclosed for the expansion of pipes for heat exchangers, including a machine frame equipped with a drive unit for pressing or pulling an expansion mandrel through a pipe as well as an expansion mandrel. In at least one embodiment, the machine includes at least one drive unit with at least one motor-driven drum as well as a band or wire guide which extends horizontally from an outlet of the drum and forwardly to the pipe, the drive unit including a set of lateral plates. In at least one embodiment, the drum is disposed between the lateral plates of the drive unit and is equipped with a band or a wire and is additionally adapted to press or pull a band or a wire with an expansion mandrel through a pipe, wherein the expansion mandrel is expandable.

Abstract: The invention relates to a method and a rolling mill for producing a seamless steel pipe in a continuous rolling process, where semi-finished material is first formed into a hollow block (8) in a rotary rolling mill, said block then being rolled in a multi-tooled continuous rolling mill (1) over a previously inserted mandrel (10) to form a tube blank (9), wherein the mandrel (10) receiving the hollow block and held by a mandrel holding and transporting device (5) disposed on the entry side is fed into the continuous rolling mill (1) and is transported back to the entry side after the tube blank has been rolled off of the mandrel (10) on an extracting rolling mill (4) connected downstream of the continuous rolling mill. An aim of the invention is to allow high production rates at the same product quality, particularly at a low drop in the temperature of the tube blanks.

Abstract: A rolling mill of rotating expander type for tubular bodies, comprising: working rollers (1, 2) arranged inclined with respect to the rolling axis; a tip (3) fitted on a beam (4), so that the tubular body is pushed in rotation between the rollers and the tip, and subjected to deformation in order to increase the perimeter; a tip-stabilizing system placed behind said tip, about the beam, and integrated in the rolling mill.

Abstract: A pilger die and a pilger mandrel which are used to produce a dashpot tube which can be used in a nuclear fuel assembly having an outer diameter of 31.75 mm or less and an inner diameter 25.654 mm or less, by processing a reduced expression zirconium alloy tube in two pilgering processes (a first step pass and a second step pass) using a single pilgering apparatus. Furthermore, provided are methods of manufacturing the pilger die and the pilger mandrel, and the dashpot tube for the nuclear fuel assembly. The dashpot tube can be manufactured by the single pilgering apparatus provided with the pilger die and the pilger mandrel.

Abstract: The present invention provides a mandrel mill and the like that is capable of not only enhancing the elongation ratio of the pipe or tube, but also suppressing a pinhole defect from occurring. The first means of the present invention provides a mandrel mill comprising a plurality of rolling stands in which two grooved rolls R11, R12 are disposed, respectively, the mandrel mill being characterized in that the roll diameter ratio for the first rolling stand and the second rolling stand is set at a value of 4.6 or over. The second means of the present invention provides a mandrel mill comprising a plurality of rolling stands in which three grooved rolls R21, R22 and R23 are disposed, respectively, the mandrel mill being characterized in that the roll diameter ratio for the first rolling stand and the second rolling stand is set at a value of 2.8 or over.

Abstract: A method for producing an ultrathin-wall seamless metal tube, which employs a cold pilger mill of mechatronics drive type including a mechanism to give a feed and a turn angle to a tube material, utilizes a roll having a tapered groove whose diameter gradually increases or gradually decreases from an engaging entry side to a finishing exit side of a pair of rolls, and a tapered mandrel whose diameter similarly gradually increases from the engaging entry side to the finishing exit side to elongate the tube material by reducing a wall thickness while expanding a mid-wall diameter of the tube material. By giving amounts of a turn angle and/or a feed equivalent or nearly equivalent to the forward stroke to the tube material immediately before the start of a backward stroke, it is possible to achieve a further increase in the reduction-rate of rolling, a further reduction of wall thickness, and improvement of dimensional accuracy of the product.

Abstract: A retract mandrel mill, comprising a mandrel mill and an extractor, the mandrel mill including a mandrel bar and being configured to roll a tube blank into which the mandrel bar is inserted, the extractor being configured to extract the mandrel bar from the tube blank that has been rolled in the mandrel mill, wherein the distance between the mandrel mill and the extractor is adjustable, and a method for rolling a tube blank by using the retract mandrel mill. As the result of the adjustable distance, even when a tube blank which is shorter than usual is rolled, there is no need to add an extra extension to the length of the tube blank to be elongation-rolled, and the wear of the mandrel bar can be suppressed so that the tube blank can be rolled efficiently and with high yields.

Abstract: In one aspect, an apparatus for manufacturing a framing member can include a translation path for transporting a metal sheet. The translation path can include a translation axis, a first set of rollers, which can include a plurality of first bottom rollers and a plurality of first top rollers, the first set of rollers can have a first centerline, and a second set of rollers, which can include a plurality of second bottom rollers and a plurality of second top rollers, the second set of rollers can have a second centerline, line, where the first centerline and the second centerline can extend away from the translation axis at an angle in the direction of translation.

Abstract: A longitudinal, multi-stand rolling mill of the continuous, restrained type for rolling hollow bodies is described, which comprises a main rolling mill (2) and an extracting rolling mill (4) in line and downstream of the main rolling mill, at a distance from the main rolling mill larger than the maximum length of the hollow body and of the spindle, and in which the spindle is extracted at the outlet of the main rolling mill in the gap between said main rolling mill and extracting rolling mill, and is laterally unloaded.

Abstract: The monitoring apparatus of production conditions in a piercing-rolling mill for piercing and rolling a billet B to produce a pipe S comprises an ultrasonic thickness meter which is installed on an exit side of the piercing-rolling mill and measures a thickness of the pipe S produced by the piercing-rolling mill, a thermometer which is installed on the exit side of the piercing-rolling mill and measures a surface temperature of the pipe S produced by the piercing-rolling mill, and a computing and displaying device which is connected to the ultrasonic thickness meter and the thermometer and displays a thickness distribution in a circumferential direction of the pipe S based on the thickness of the pipe S measured by the ultrasonic thickness meter, and a surface temperature distribution in a circumferential direction of the pipe S based on the surface temperature of the pipe S measured by the thermometer.

Abstract: A tube rolling plant (R) with multi-stand rolling mill having two or more rollers, for implementing a mandrel rolling process with controlled speed has a mandrel (31) which is inserted into the hollow body (39) from the frontal opening thereof by passing it first through the rolling mill (5). An opposite movement (L3) with respect to the rolling direction is imparted to the mandrel (31) by means of the hooking device (61) when rolling the hollow body (39) and the rear end of the rolled tube (42) is extracted at the end of the rolling operation.

Abstract: There is provided a production method of an internally ribbed steel tube, capable of forming spiral ribs stably so as to reduce troubles at the time of cold drawing for forming the spiral ribs of the steel tube. In this production method, the spiral ribs can be formed stably so as to reduce troubles at the time of cold drawing for forming the spiral ribs by straightening bends of a blank tube before the cold drawing for forming the spiral ribs, by optimizing the direction of the spiral rib formation after the bend straightening, and by correcting the drawing schedule depending on the blank tube. The obtained internally ribbed steel tube is well applicable to an increased capacity and a higher temperature/higher pressure operation of a boiler because the steel tube is provided with high formability and excellent quality as a boiler steel tube.

Abstract: A plug 2 used for a piercer according to the invention includes a tip end portion 23, a cylindrical portion 24, a barrel portion 25, a mandrel coupling portion 22, and an injection hole 21. The injection hole 21 penetrates from the surface of the cylindrical portion 24 to the surface of the mandrel coupling portion 22 and an externally supplied lubricant is injected from the hole. A clearance forms between the pierced material and the cylindrical portion 24. The injection hole 21 is formed at the cylindrical portion 24, and therefore the material in the process of piercing does not contact the injection hole 21. Therefore, an inner surface defect attributable to the contact between the material and the injection hole 21 can be prevented from being generated.

Abstract: A process for producing seamless pipes which comprises conducting a piercing rolling step, a elongating rolling step using a mandrel bar, and a sizing rolling step and subsequently conducting a product heat treatment. In the process, when the carbon-equivalent weight, namely the sum of the weight of graphite in the lubricant and the carbon content in the organic binder, per unit area of the lubricant adhering to the mandrel bar surface in the above-mentioned step of elongating rolling is expressed by C (g/m2) or the maximum extent of carburization in the inner surface of the pipe to be heat-treated but prior to the heat treatment is expressed by ?C (% by mass), the heating temperature for the pipe to be heat-treated is expressed by T (° C.

Abstract: The present invention relates to a system and method for rolling a seamless tube. The plant comprises a main rolling mill with adjustable rolls for mandrel-rolling a semi-finished tube. The plant also comprises a fixed-roll extracting/reducing mill positioned downstream of the main rolling mill. The extracting/reducing mill is designed to extract the semi-finished tube from the mandrel and reduce its diameter to a predetermined value close to that desired for the finished tube. Finally, the plant comprises a adjustable-roll sizing mill. The sizing mill is positioned downstream of the extracting/reducing mill. This sizing mill is designed to adjust the radial position of the rolls and define the diameter of the outgoing tube.

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: A method for producing an ultrathin-wall seamless metal tube, which employs a cold pilger mill of mechatronics drive type including a mechanism to give a feed and a turn angle to a tube material, utilizes a roll having a tapered groove whose diameter gradually increases or gradually decreases from an engaging entry side to a finishing exit side of a pair of rolls, and a tapered mandrel whose diameter similarly gradually increases from the engaging entry side to the finishing exit side to elongate the tube material by reducing a wall thickness while expanding a mid-wall diameter of the tube material. By giving amounts of a turn angle and/or a feed equivalent or nearly equivalent to the forward stroke to the tube material immediately before the start of a backward stroke, it is possible to achieve a further increase in the reduction-rate of rolling, a further reduction of wall thickness, and improvement of dimensional accuracy of the product.

Abstract: A piercing and rolling plug has a film composed of oxides such as Fe3O4 and FeO and Fe (metal) as being formed on the surface of the base metal by electric arc spraying using an iron wire whose main component is Fe and, owing to this film, a plug excellent in heat-shielding and seizure-preventing effects can be realized and the lifetime of the plug can be prolonged. Further, in regenerating this plug, a film can be re-formed via the steps of shot blasting of the as-used plug in piercing and rolling and electric arc spraying in that order; thus, it is possible to regenerate the plug at low cost and in a short period of time.

Abstract: The plug is for expanding the inside diameter of the end portion of a metal pipe. Its cross section is a circle, and includes a taper portion and a parallel portion connected to the tail end of the taper portion. The diameter of the taper portion gradually increases from the head end of the taper portion to the tail end of the taper portion where the diameter is D1. The axial distance LR from the point where the diameter D2=D1×0.99 to the tail end where the diameter is D1 satisfies the Expression 22?LR/((D1?D2)/2)?115. The taper angle on the surface where the diameter is D2 is larger than or equal to the taper angle on the tail surface of the taper portion following the point where the diameter is D2. The diameter of the parallel portion is D1.

Abstract: In cold rolling of a seamless metallic tube with a cold pilger mill, when a reduction ratio of an outside diameter becomes excessive in comparison to a reduction ratio of a wall thickness, strain in a circumferential direction on flange regions becomes excessive. As a result, compressive stress in a circumferential direction becomes excessive, so that wrinkle imperfections are generated inside a tube and folded on groove bottom regions to become folded defects. This process is repeated to be developed into inside defects. When a hollow shell is produced by the Mannesmann-mandrel process instead of the extrusion process, inside wrinkle imperfections are generated with a sizing mill (a stretch reducer or a sizer) at a stage of hollow shell. Since the inside wrinkle imperfections further grow in cold rolling, it is necessary to pay attention thereto. In consideration of these, (a reduction ratio of an outside diameter/a reduction ratio of a wall thickness both in a cold pilger mill) is set to not more than 1/2.

Abstract: An apparatus for sizing a pipe end comprising: a plug 3 for sizing the pipe end; a chuck 2 for clamping the pipe; and shifting means for shifting the position of the plug 3 and/the chuck 2, which are placed successively from the end of the pipe 2, and the plug 3 has a circular cross section, and is constituted by a taper portion 31 and a diameter equivalent portion 32 continuously formed from the tip of the plug in succession. The outer diameter of the taper portion 31 is gradually expanding from the tip toward the rear end while satisfying the following formulas (1) and (2). The chuck 2 is capable of changing clamping position of the pipe 1. This apparatus makes it possible to size the inner diameter of a pipe end with superior dimensional precision 22?LR/(D1×0.01/2)?115 ??(1) R2?R1 ??(2).

Abstract: The invention relates to a method and a rolling mill for producing a seamless steel pipe in a continuous rolling process, where semi-finished material is first formed into a hollow block (8) in a rotary rolling mill, said block then being rolled in a multi-tooled continuous rolling mill (1) over a previously inserted mandrel (10) to form a tube blank (9), wherein the mandrel (10) receiving the hollow block and held by a mandrel holding and transporting device (5) disposed on the entry side is fed into the continuous rolling mill (1) and is transported back to the entry side after the tube blank has been rolled off of the mandrel (10) on an extracting rolling mill (4) connected downstream of the continuous rolling mill An aim of the invention is to allow high production rates at the same product quality, particularly at a low drop in the temperature of the tube blanks.

Abstract: Seamless pipes excellent in quality features with high productivity is made by a by carrying out piercing-rolling using a piercer provided with a pair of inclined rolls. The piercing-rolling is carried out under conditions such that the plug tip draft (TDFT) or the root of the product of the plug tip draft (TDFT) are controlled along with the number of billet revolutions (N), namely (TDFT×N)0.5. In addition, positions of the inclined rolls are controlled in connection with the gorge draft (GDFT) indicating the ratio of the roll gap (Rg) which is minimal in the gorge section between the inclined rolls to the billet outside diameter (Bd). The piercing-rolling is carried out using a plug having a particular shape.

Abstract: The invention relates to a rolling mill for rolling stock to be rolled (6), having a planetary cross-rolling mill (20) and a subsequent further rolling mill in the rolling direction, the subsequent mill comprising a mandrel rod (10) having a length that is larger than the distance between the planetary cross-rolling mill (20) and the further rolling mill in the rolling direction.

Abstract: A plug 2 used for a piercer according to the invention includes a tip end portion 23, a cylindrical portion 24, a barrel portion 25, a mandrel coupling portion 22, and an injection hole 21. The injection hole 21 penetrates from the surface of the cylindrical portion 24 to the surface of the mandrel coupling portion 22 and an externally supplied lubricant is injected from the hole. A clearance forms between the pierced material and the cylindrical portion 24. The injection hole 21 is formed at the cylindrical portion 24, and therefore the material in the process of piercing does not contact the injection hole 21. Therefore, an inner surface defect attributable to the contact between the material and the injection hole 21 can be prevented from being generated.

Abstract: A rolling mill (10) for processing seamless tubes comprises a plurality of rolling units (U) that are sequentially arranged along a rolling axis (L), each of which is provided with at least three removable working rolls (12), which are each equipped with a groove (12a) for accommodating the tube to be worked; the rolling mill comprises a mandrel suitable to be fitted in the tube cavity during the process; the tube is worked by being sequentially passed, with the mandrel (22) fitted in the tube cavity, within the grooves (12a) of the rolls (12) of the rolling units (U) such that the outer diameter of the tube (T) is reduced; in order to have low capital and production costs, each rolling unit (U) has an unchanged nominal diameter

Abstract: The present invention provides a seamless tube piercing/rolling plug and a seamless tube producing method in which piercing/rolling is performed with an inclined rotary piercing mill while the seamless tube piercing/rolling plug is used as a piercing tool. The seamless tube piercing/rolling plug is used while a front part and a rear part of the split plug are held as an integral plug, at least the front part is made of low alloy steel, and oxide films are formed on surfaces of the front part and rear part. The present invention also provides a seamless tube piercing/rolling apparatus and a seamless tube producing method in which the front part and/or rear part is replaceable in a tube making process line using the seamless tube piercing/rolling apparatus.

Abstract: A seamless tube is manufactured while effectively suppressing the occurrence of carburization in the seamless tube without interfering with operations. A seamless tube is manufactured by a step of washing at least a portion of a conveyor installed in a conveying step of a mandrel bar B which is situated from a lubricant applying device 7 to the entrance of a mandrel mill 8, a step of washing, on the upstream side of the lubricant applying device 7, a mandrel bar B which was used for elongation rolling, and a step of applying a non-graphite-based lubricant to the mandrel bar B with the lubricant applying device 7, wherein the conveyor and the mandrel bar B are each washed such that the amount of graphite C2 (g/m2) adhering to the surface of the mandrel bar B before it is provided to elongation rolling and the amount of carbon C1 (g/m2) contained in the organic binder of the applied lubricant satisfy Equation 1: 0.08×C1+0.05×C2?3 and Equation 2: 3?C1+C2?50.

Abstract: A tubular product comprises a side section having outer surfaces disposed along a parallelogram and a bottom section formed on one end of the side section. The outer surfaces of the side section are pressure formed by a roller. The tubular product preferably is manufactured from a tubular material by a process comprising the use of a device having a roller that is configured to engage with a side section of the tubular material. The device also comprises a mandrel configured to position the tubular material so that the roller can apply pressure against at least a portion of the outer surfaces of the side section and can extend the side section of the tubular material to form the product.

Abstract: The present invention provides a seamless tube piercing/rolling plug and a seamless tube producing method in which piercing/rolling is performed with an inclined rotary piercing mill while the seamless tube piercing/rolling plug is used as a piercing tool. The seamless tube piercing/rolling plug is used while a front part and a rear part of the split plug are held as an integral plug, at least the front part is made of low alloy steel, and oxide films are formed on surfaces of the front part and rear part. The present invention also provides a seamless tube piercing/rolling apparatus and a seamless tube producing method in which the front part and/or rear part is replaceable in a tube making process line using the seamless tube piercing/rolling apparatus.

Abstract: A seamless tube producing method uses a piercing/rolling plug wherein piercing/rolling is performed with an inclined rotary piercing mill while the seamless tube piercing/rolling plug is used as a piercing tool. In one mode, a front part and a rear part of the split plug are held as an integral plug, the front part being made of low alloy steel, and oxide films are formed on surfaces of the front part and rear part. In a second mode, the front part and/or rear part are replaceable via a removable mounting wherein a mandrel bar holding the plug goes through the rear part, the mandrel bar being coupled with the front part. A thickness of the oxide film formed in the front part can be 200 ?m or more and the oxide film of the front part can be thicker than the oxide film of the rear part.

Abstract: The present invention relates to a making method for a seamless metallic tube with a tilting roll type piercing rolling mill (piercer). According to the making method for a seamless metallic tube of the present invention, the rotary forging effect and the circumferential shearing strain can be significantly suppressed without generating uncompleted engagement of a billet. Accordingly, a product having reduced inside defects and excellent inside quality can be produced in high productivity. Further, by strengthening a plug nose rolling portion, a sharpened plug nose is obtained and an engagement limit can be increased. Additionally, a product further excellent in the inside quality can be efficiently produced. Accordingly, the present invention can be applied to wide fields of the piercing rolling of the seamless metallic tube.

Abstract: A tubular blank (22) is rolled on a mandrel (14) in a pilgrim rolling mill. In a first rolling stage, a first part of the blank (22) is rolled on a first part (18,19) of the mandrel (14), with a reduction of the outside diameter of the blank (22) to the outside diameter of the guide tube and a reduction of the wall thickness of the blank (22) to one of a first wall thickness (e1) and a second wall thickness (e2) exceeding the first wall thickness (e1). The mandrel (14) is advanced in the axial direction. A second part of the blank (22) is rolled on a second part (20,21) of the mandrel spaced from the first part in the axial direction with a reduction of the outside diameter of the blank to the outside diameter of the guide tube and a reduction of the wall thickness of the blank (22) to the other of the first wall thickness (e1) and second wall thickness (e2).

Abstract: An apparatus for producing an internally grooved seamless tube by rolling. The apparatus has pressing rolls 3 and back-up rolls 20, which work with a constant load under control by the load detector 21 to form uniform grooves without breaking the mother tube.

Abstract: A 2-roll piercing mill for producing hollow blocks from a rolled material comprising high alloy steels has guide tools for the rolled material. The guide tools are arranged for closing a reforming zone of the piercing mill transversely with respect to the rolling axis as the hollow block is pierced. In this arrangement, each of the guide tools includes a base body made of a carrier material and a working face made of a material that has antiadhesive properties with respect to high alloy steels and high hot strength. Prior to the piercing operation, the temperature of either the working face or the entire guide tool is raised above room temperature to avoid high thermal stresses.

Abstract: This invention provide a plug and a mandrel bar for use in rolling a seamless steel pipe of which life can be substantially improved more than that of the prior art under a severe condition of use always exposed to a high temperature and high load. The entire plug or the mandrel bar or at least the surface layer of the extremity end and the work section of it is made of ceramics. In addition, this invention provides a method for manufacturing a seamless steel pipe using such a plug or mandrel bar as described above.

Abstract: A piercing mill and cannon exchange method therefor which can automate exchange of a cannon and can cope with flexible production of a variety of differently-sized seamless steel tubes in small quantities. The piercing mill including means for pivoting a cannon holder which holds a cannon and means for sliding the cannon holder along a pass line, through combined above-mentioned means, the cannon holder is pivoted so as to come into alignment with the pass line, is slid along the pass line, and is clamped at a predetermined location. The cannon exchange is characterized in that a cannon holder which retains the cannon in the direction perpendicular to the pass line is pivoted so as to come into alignment with the pass line, is slid along the pass line, and is then clamped to the main frame of the piercing mill. Therefore, it become possible to automate exchange of a cannon in accordance with a changeover and to considerably reduce working hours.

Abstract: A method for manufacturing a seamless pipe, comprises:preparing a billet made of an alloy steel or an alloy;joining a steel plate to an end surface at which piercing of the billet is commenced;preparing a piercing plug made of Mo, a Mo alloy or a heat-resisting steel;hot-piercing the billet by using the piercing plug to produce a hollow shell; androlling the hollow shell to produce a seamless pipe.

Abstract: A method and device for placing plugs on plug mills, in which, after the completed rolling of a tube, the plug is freed from bearing against a plug rod and, owing to its weight, moves downward out of the rolling line, is recooled and is raised again into the region of the rolling line. According to the invention, when being raised the plug moves on an elliptical track and, before being deposited, assumes a waiting position which is located at approximately the same level at a lateral spacing from the rolling line.

Abstract: A method for manufacturing a seamless pipe, comprises:preparing a billet made of an alloy steel or an alloy;joining a steel plate to an end surface at which piercing of the billet is commenced;preparing a piercing plug made of Mo, a Mo alloy or a heat-resisting steel;hot-piercing the billet by using the piercing plug to produce a hollow shell; androlling the hollow shell to produce a seamless pipe.

Abstract: A single-piece self-guiding, high integrity high mill plug for producing seamless tubular steel products in rolling mills is provided. The high mill plug is produced from a single a casting having a substantially bullet shape with an opening at each end and a passage therebetween to allow gases which develop during the casting process to escape. By designing the high mill plug to be produced from a single casting with no dead-end cores, the latent surface defects associated with the prior multi-piece casting designs are substantially avoided and the casting used to produce the single-piece self-guiding high mill plug has a very high integrity. The single-piece self-guiding high mill plug substantially improves rolling mill operations for producing seamless tubular steel products by eliminating both time and labor expenses associated with disassembling and reassembling the worn work plug sections as required by the prior art multi-piece high mill plug designs.

Abstract: In a mandrel mill for elongating and rolling a hollow shell, with a mandrel bar inserted, by passing the hollow shell, a four-roll stand for diameter reduction used to reduce only the outer diameter of the hollow shell is disposed as the first stand, a group of two-roll stands for wall thickness reduction used to reduce the wall thickness of the hollow shell is disposed following the four-roll stand, and a four-roll stand for eccentric wall cancellation used to cancel any nonuniform wall thickness in the circumferential direction of the hollow shell is disposed as the final stand. The ratio (D.sub.i /D.sub.m) between inner diameter D.sub.i of the hollow shell on the outlet side of the four-roll stand as the first stand and outer diameter D.sub.m of the mandrel bar is 1.05 or less.