SA111320132B1 - Tube rolling plant - Google Patents

Abstract

The present invention relates to a plant for rolling a seamless tube, typically of medium-to-large diameter, and the plant includes a main rolling mill with adjustable rolls for rolling a semifinished tube with a forming core mandrel. The factory also includes a fixed-roll extraction/reducing mill located in the same downstream as the main rolling mill and in series with it. An extraction/reduction plant is designed to extract the semi-finished tube from the preform core and reduce its diameter to a predetermined value near the desired for the finished tube. Finally, the plant includes an adjustable-roll sizing mill and is off-line for the latter. This sizing mill is designed to adjust the radial position of the rolls and determine the diameter of the outgoing tube. The invention also relates to a method for rolling a seamless tube.

Description

Y

Pipe rolling factory

Tube rolling plant Full description Background of the invention for continuous rolling plant method The invention also relates to the method of .medium-to-large diameter sale) by the aforementioned seamless metal tubes. It is known to produce seamless metal tubes 0 by starting billet successively to a primitive iron bar plastic deformation

IVY In an oven to a temperature of about billet, the iron bar is heated, first step, first step, pierced, and then. And then the iron rod is punched lengthwise to obtain a semi-finished perforated product YAS to; 1.9 times greater than the penis and the length of the thick wall semifinished article semifinished in this semi-finished product primitive mandrel. After that, the formation core 0 (referred to herein as rolling mill) is inserted, and this semi-finished product is then passed through a rolling mill article capable of gradually raising the wall by lowering operations (‘main rolling mill Jared’ The appropriate finished product and the length increase for the finished product are diameter-reducing operations kill sang Each rolling units includes several ead rolling units and includes the rolling mill; it is also known as profiled grooves with gaps that take standard shapes Rolls A base of 4 on which unit 0 cylinders are installed, three in number and typical shapes, profiled rolls. Rolls with standard shapes are usually rolling units, which are launched by the tube rolling unit of the tube. Profiles: heart arrangement, main rolling management mill The basic rolling mill requires Qala and, as mentioned, made of radial thrust forming inside the tube that handles, capable of facing the radial thrust v

rollers during rolling and to exert this counter effect; The forming core must be solid

In the radial direction, moreover, to ensure a high quality finish

high-quality finish for the inner surface of the tube The forming core must have a surface

The outer surface is as smooth as possible. Because of this requirement ¢ it will be very difficult to manufacture mandrels with several parts joined together. and the link area

The joining zone is, in fact, necessarily distinguished by the irregular surface, and moreover

Very radial rolling to withstand the radial rolling pressure dul zone This zone will be eld

pressure masked.

International Patent 017 discloses a seamless pipe rolling mill, usually with

The mandrel is medium to large in diameter and the plant includes a main rolling station with adjustable rolls of 0

For a semifinished tube.

European Patent 1501977 discloses a method of elongating a mandrel mill for the manufacture of metal tubes; Especially seamless tubes 5868:01888. The patent reveals a seamless steel tube like a "metal tube".

0 European Patent No. 1,918,074 discloses an apparatus and method for detecting pipe defects. In particular, the device and method for detecting defects in tubes, as well as detecting defects growing in large tubes, mother tubes, which are made by rolling hollow shells using a heavy-duty mill automatically. None of the foregoing documents disclose what has been disclosed in the present invention.

It is also known to use a retained mandrel that restricts the core of the formation

Y. is pivotal and reserved for optimization at a controlled speed. We find that this solution Jal has a significant drawback defect. The single section actually improves the inverting of the formation; while braking; Axially along the rolling mill and connected successively during sale conditions. Full formation.

cdeformation conditions at all rolling stations and within rolling stations; The forming core is subjected to high thermal and mechanical stresses as a result of the deformation energy and ml friction by the sliding contact of the tube material, and thus the passage through more than One rolling station causes a significant increase in the temperature of the forming core (cmandrel temperature), and this causes the need to prepare several forming cores, several mandrels, that are identical to each other, so that each of them may cool down appropriately at the end of the rolling and then slide for the next rolling cycle. rolling cycle In addition, it must be taken into account that the core of the individual mandrel 0 must be completely made of high-quality material, especially to withstand the stresses resulting from rolling in a typical way. From the foregoing, it will become clear that the costs considered considerable outlay are required to store the mandrel stock to enable ensuring the operation of the basic rolling mill Jane operation. In the same Jaze Downstream 1 primary stream, the pipe is extracted from the core of the formation and 00 final finishing operations are carried out to obtain a pipe that is compatible with suitable quality control standards. The basic parameters are the main parameters that must be To change is the outer wall thickness, hilly thickness, outer diameter of the tube. Currently, two different types of factory are known that are capable of performing final finishing operations. The first type of factory imagines the management; In the same stream as the main rolling mill and in series with it for the extracting mill 6 to extract the semi-finished tube

This is a semifinished tube from the formation core 0, and this sale extraction includes three bases 5. During subsequent processing operations, it is no longer possible to directly adjust the thickness of the wall 1 of my tube wall . Thus it is conceivable; in this kind of plant; Performing a control of the wall thickness close to the extractor in this way; If the semi-finished pipe has a wall thickness different from the desired thickness, it is possible to perform an automatic adjustment of the main rolling mill to adjust the thickness along the following pipe segments. A csizing mill is placed away from the line, on its vines. In the same stream of the extractor and the thickness control point, and their number. This sizing plant includes several Al (VY) sale) fixed stands that are capable of determining the final diameter ya of the pipe so that it conforms to the required standard 40. In order to obtain a good result in relation to the diameter, it is envisaged to ensure a temperature Uniform temperature of the Jah tube is a suitable furnace so that the uniform contraction of the tube is also achieved during subsequent cooling and during this processing step. Primary rolling at different temperatures along the various segments; Depending on the geometric conditions of the duct and the transient factors during the method. And the furnace that follows the sizing lab has “ie dimensions” to enable the whole tube to be joined inside so that it may have a uniform temperature around 2400 and depending on the effect of 0 sizing lab; The final diameter of the pipe shall be according to the required standards. (lal) thickness may fail A anyway; In compliance with the standard because the effect of the size-taking laboratory adjusts in a manner that is uncontrollable and sometimes unpredictable: the wall thickness is unpredictable. In the same stream as the size-taking laboratory, a station may be prepared

For controlling 8 the final thickness of the tube also “dy if necessary”; The thickness of the semi-finished product is adjusted against the “semifinished article upstream” in the heating plant to base 0 and obviously; anyway; That this control operation takes place at a late stage and that the conditions that produced a deviation of 0 in the thickness from the required standard may change again in the meantime and thus the invalidating effectiveness is corrected control process. It should be noted that this is the first type of plant; Although it is widely used; It was not without defects SA .drawbacks the furnace yall between extracting mill and sizing mill introduces additional outlay cost and since it stays tb in 0 running; alg High running costs Tons. Furthermore; Logically, point 108190081 Jere requires taking the fixed-roll sizing mill a large mandrel stock p:h1 to enable the preparation of the various required diameters; The different steels used and their characteristics, and finally, as mentioned by lila, control is carried out in the final thickness of the pipe wall only indirectly, and it is 0 other than WE to ensure ad small tolerances small tolerance values. The second type is imagined from the well-known factory (aii in the same stream as the rolling mill grad) ol the well-known Gi ley with it from des extraction/sizing mill. This extraction / size taking plant includes several adjustable-roll stands, and thus it is possible to extract the tube from the formation core 0 and to control the final tube diameter, and the wall thickness is controlled 85 Post-extraction/volume taking. In this way; If the controlled tube has a wall thickness different from the desired thickness; An automatic adjustment is possible

For the basic rolling mill to adjust the thickness along the following tube sections. Although this type of mill is clearly more compact than the one described, i.e., there are a number of defects that it uses that were not particularly distinguished. The extraction/volume-taking lab actually includes many tunable rules (oo) (10-a) and is therefore a very complex fas and costly machine. Moreover, it is not possible to perform accurate control. For the diameter on the same line on this line - “H. In fact, it should be remembered that” at the end of the rolling process, the pipe moves along the factory at a speed of about 1-2 m / s. Therefore, it is very difficult to apply feedback control. Which allows checking tube parameters and real-time modification of rolling mills, and this difficulty increases when there are temperature variables along the tube. Such temperature to cause the corresponding changes in the final diameter of the tube.Thus the objective of the present invention is limited to overcoming Ue at least the aforementioned defects with reference to the previous field. Continuous rolling allows the most efficient control over both the outer diameter and wall thickness of the beveled tube. Furthermore; The task of the present invention is limited to setting up a continuous rolling mill which requires simple initial cost and low procedure costs. cial 0 The task of the present invention is limited to setting up a continuous Ally factory that allows simpler management from a logical point of view.

A

And by 1, and the aforementioned goals and tasks are achieved by means of a factory, as mentioned in the item

AY method according to the element Brief explanation of the drawings by Layla Hana from Lad Distinctive features and other features of the invention will be out of description; Prepared a number of examples of embodiment; provided by unspecified example; Referring to the accompanying drawings © in which: A block diagram represents a first type of rolling mill according to the previous field; Figure 7 shows a diagram representing a rolling mill according to the invention; A schematically shows a basic continuous rolling mill used in the factory according to the invention. For rolling a semi-finished tube, the radial position old has a half position in the core of the formation. Accordingly, the plant, according to the invention, includes an extraction/reduction plant fixed to a rolling mill placed in the same stream as the main rolling mill, and in a row a fixed-roll extraction/reducing mill 0 is designed to extract a semi-tube extraction/reducing mill with it. This extracted/reduced mill is finished from inverting the formation and to reduce the diameter of the semi-chamfered tube to a pre-determined value near the desired one for the chamfered pipe. The factory includes an adjustable diameter of the cylinders. This sized modulus is placed in the same stream as the modulus 0 (Al) extraction/reduction is likely to be determined and off-line for it. Referring to the factory of the tube whose longitudinal axis Jia, which Jas rolling axis q straight half-line on the direction of the straight half-line "Radial" is treated. It shall have an ads origin which is perpendicular to the axis and according to certain embodiments of the plant according to the invention » The basic rolling mill is distinguished as using slow sola cores! The present description; understands the term Ay slow mandrel Sections means the core of the formation that is held so that none of its sectors aly "mandrel ©" influence two successive rolling stations. In particular, by referring also to the associated Figure 4, the following equation is obtained:

Vi > 71 minimum represents the minimum internal axial distance d VY represents the molding overturning speed Vin where is the time of Jia Tp ?; And 4 successive rolling stands between two consecutive rolling bases. Interaxial distance 01 for application: The following ALE equation is the rolling time equation. Vi and 01 of the tube length is the length of Jin L where Foal is the length of 0 modulus

Fo required to operate the basic rolling mill (FY) From the foregoing, it can be understood that the Vo minimum length used in the factory according to the invention may be relatively short. It will be the least length (i.e. D overall interaxial distance required in fact Equal to the total internal axial distance (:58)_increased by displacement and last rolling station The following: the previous value also the value equations and the equations are given 00 simplifies the basic rolling mill and includes four cf and in the schematically shown embodiment in the figure only. But four stands, come back

10 experienced people may immediately understand how the same concepts can be applied to rolling mills with more than ; limited bases. This allows for a specified displacement of the forming core. Vip speed and average values. m5 _ to invert the modulation 77. Taking into account the average values of displacement of the inverting minimum length shown previously, the minimum length of the variables assumed will be typical of the variables ©

PY 0+m8; Between about © and 6 meters. This length allows the manufacture of preform cores (IS (FY) conventional retained mandrels at a lower cost than conventional retained mandrels from the preform core displays individual section and moreover; The overall heating is only one, the total heating of the rolling stand due to the effect of the rolling base of the forming during the method is determined. From this fact derives the possibility of making a forming core using materials 0 conventional for faster than traditional 1 which is less expensive than what is used. For operation cores materials as a result. This allows for rapid Jaa reduction and cooling of single type required to produce one type mandrel specimens types of forging hearts yo the forging heart stock as a whole clearly shows economic advantages (58 reduction of tubules. We find that Substantial economic and logistical advantages, moreover; As can be seen in the figure; Associated » Not all axial distances 34 rolling stands separating four rolling bases All three interaxial distances 1 interaxial distance separating the first are similar. The internal axial distance 0 is the one that separates the third base from the fourth base; od and the internal axial distance atl from the base is the second internal axial distance; Which separates the second base dla is exactly the same. And on any

11 mini is larger than the other two spaces. In fact, the small support stand aa is placed on the base between the second rolling base and the third rolling base, given that the YY heart of the forming core VI support stand aaah along the forging cantilever mill, on the other hand, will represent a prominent support that The second inner axial distance is greater by the distance ϕ and is assumed as in the figure during the fully rolling method FY l than the other two; And each of the sectors of the modulation core distance © and in connection with Sp > often has the length of the section. It travels along the sector of the “entire rolling process” with the second internal axial distance. It is possible to specify a sector for the modulation core “© with a length equal to at least [which does not make any rolling either with the second base or with the third base.This segment of length [ is from the formation core 37. Referring to the example taken in TYY and YY between two TV parts, it is available to set up a joint length between approx. 1,5 and © m. TY from the formation core TY each of the two parts (Bila) will have consideration 0

NY With these lengths, it is possible to gradually simplify the manufacture and management of cores option There is an option of “composite mandrel using overlapping cores” dh and moreover only. On the contrary; When using a worn portion where a “worn portion” replacing is requested for replacement, cconventional non-composite mandrels must be replaced only. Furthermore; When using the heart of local wear completely, even if it is exposed to local corrosion only 1 high-quality materials There is a need for the possibility of using high-quality materials (She forms those parts that are linked in the first rolling rules) sale) stress portions for parts and the use of less expensive materials for parts that are less stressed. We find that the possibilities offered by the rolling mill are highly operating costs. Slow composite mandrel solution known here as slow composite mandrel solution. It is possible to set up a basic rolling mill which is very suitable for marketing. And according to the embodiments of the rolling mill according to the invention “in the same stream as the extraction / reduction plant” a means of measuring wall thickness

VY

for the tube And in those embodiments; The main rolling mill is able to adjust the radial position of the wall thickness of the tube. Measurement of the rolls based on the size and according to specific embodiments; The volume taking laboratory shall include a means of measuring the temperature of the inlet tube and in such embodiments; It is an outgoing tube and a means of measuring the diameter of the continuous tube, the incoming tube of the cylinders, depending on the radial position to set the radial position. Rolling according to the invention »against the stream of the dime rolling mill and according to embodiments of the piercing mill and the basic billet mill; A furnace for heating a ferrous iron bar lengthwise to obtain a perforated semi-finished product with a thick wall and a length 1.5 to 4 times greater than that of a primitive iron bar. cutting station size; A device for cooling the tube to room temperature and for cutting the tube to predetermined lengths. The plant according to the invention is particularly suitable for rolling seamless tube of diameter (inch (TY) indicates medium to large. This latter expansion refers to diameters greater than 178.7 mm (Y in.) To) 00 mm typically A to diameters between 118.7 mm and a 17-8 roll rule and according to an embodiment of the invention; Includes extractor installed. This plant is referred to as an extraction / reduction plant because it is capable of extracting the tube that is treated from the core of the formation and to reduce the diameter of the semi-finished tube to a predetermined value close to the final value. We find that the method of measuring the Ys wall thickness of the tube is optional; It can adjust the radial position of the cylinders from the main rolling mill. In fact, we find that the possibility of adjusting the pipe wall thickness directly is determined by the rolling mill

VY

The basic one that works with the core of the formation. The extraction/reduction plant alternatively operates without inverting the preform and is directly adjustable for tube diameter. We find that adjusting the diameter by the extraction plant / taking the size includes; As a secondary effect.; change in thickness. And this change; anyway; It cannot be precisely determined in advance. ° According to one embodiment of the invention; The TY size taking plant includes a rolling base type with radially adjustable cylinders. those rolling bases with adjustable rolling pins; For example; It may be similar to what was described in European Patent No. 19778977 granted to the same applicant. The sizing mill is capable of reducing the pipe diameter to a predetermined value required for a pipe bevel. With the use of adjustable rolling mills in the sizing plant, it is possible to obtain, using the same cae 2,5 group, different final diameters; For the change in diameter up to about 0 for the rollers to increase the period of their work and the different thermal contraction JST (ages of the rollers) may be controlled, it may achieve la reduction of the materials and the resulting thickness. Of rolls equipped with a rolling mill, this major reduction may be estimated (Jars) for the overall stock of rolls by reference to WJ on AY at 0 extraction/reduction and size-taking factor. And as dala mentioned the sizing plant did not monitor in line with the parts described for the plant. This means that the tube has moved; During the coda processing step, the axial speed is slower than it reaches at the end of the previous processing steps. Typically; When leaving the main rolling mill, the inside of which exhibits the greatest increase in speed; The tube travels at a speed of about 1-5 m/s. The optimum rolling speed 01 for the calibration of the outer diameter of the tube has an alternative to be established as in the range between 1.7 m/s and about 1.9 m/s. According to one of the factory embodiments according to the invention” the tube travels at about 0.9 to 177 s in the volume taking laboratory.

1 That the control is in the radial position of the feeding speeds and at the charging speeds of the cylinders, which are optionally sized to be taken into account, in real time; Measuring the temperature of the following segments of the inlet tube and the diameter of the continuous tube. We find that managing the possibility of real-time control of the movement of the rolling rolls depends on the temperature of the tube, which means that the differences in temperature along the length of the said tube may be managed. In this way, it is no longer required to set up a furnace to ensure a uniform temperature of the tube. With this plant, it is possible to achieve the ideal finish of the tube, and thus to obtain the very small diameter. For the first type of former field factory; The final calibration of the pipe diameter has absolutely no effect on the wall thickness. And in fact; Calibration is carried out in 0 of the invention; By means of a small number of rolling bases with adjustable rollers. On the one hand, Ty is a factory in a well-known type; The final calibration is carried out by means of a dozen or bases with “oS” cylinders, in relation to which the tolerances related to the normal wall thickness Led are installed. It must be taken into consideration that it is usually better than what has been achieved in the previous field, with the type 7718 produced by the factory according to the invention being the first from the factory. In particular; It may be taken into account that the thickness tolerances according to the invention are specified; even in 10+ with thin wall thickness or high alloy steels; to the value between critical cases

(30) V nominal thickness tolerance and on the other hand; Endurance up to +79. With regard to gad) the yield in the well-known factories of the first type, the tolerance in relation to the normal thickness is usually small dla in the well-known factories of the second type; on any 0

relatively; But towing tolerances have a very popular alternative.

yo, especially if they are of darge-diameter tubes, and it must be mentioned here that the tubes are large in diameter and in intrinsic weight as a result of their internal ovalization, they are commonly exposed to the “Gy” wall “creep” metallic materials Hall hall materials display reality; In some conditions of constant stress, increasing deformation, that is, increasing deformation, may be taken into account that this phenomenon occurs at temperatures set above half of the melting temperature of the material © and these conditions rise for the finished tube Recently, Kelvin measured in the degree Kelvin cmelting temperature in the well-known factory of the second type. And in fact; When leaving the extraction plant / taking a cylinder size of about 001 m. Lila installed rolling mill; The tube has a high temperature when leaving the volume taking laboratory; The cp lad grades are obtained in a factory according to the reduction taken into account in the phenomenon of (Pho) the low temperature of the chamfered tube (about 0). Typical large-diameter pipes. The rolling method according to the invention includes the following steps: Rolling a semi-finished perforated product with a forming die in a rolling mill with adjustable cylinders until a semi-finished pipe is obtained; 0 Extracting the semi-finished pipe from Formation core; - ¢predetermined value Reducing the diameter of the semi-finished tube to a predetermined value - Whereas the steps of extracting the core and reducing the diameter of the semi-finished tube are achieved by a laboratory - Reduction/reduction fixed with one rolling cylinder placed in the same mill stream Basic rolling and in series with it; 0 pipe diameter to a predetermined value, in which calibrating = pipe diameter is obtained;

= by means of a sizing laboratory in which the radial position of the cylinders is adjustable; - in the same stream as dere subtraction/reduction; - Off line for the extraction/reduction plant.

according to certain embodiments; The rolling method according to the invention also includes steps for measuring wall thickness

oo the tube in the same stream of the extraction/reduction plant and; Based on this analogy; Position setting

The radius of the main rolling mill cylinders.

According to certain embodiments of the rolling method according to the invention, the tube diameter calibration step is carried out by adjusting the radial position of the cylinders based on measuring the temperature of the inner tube of the sizing laboratory and based on measuring the diameter of the tube leaving the sizing laboratory.

1 according to certain embodiments; The rolling method according to the invention may include other steps before rolling a semi-finished perforated product by turning the preform. In particular the rolling method according to the invention may include the steps of heating an iron bar in a furnace and perforating the iron bar lengthwise to obtain a semi-finished perforated product; with a thick wall. according to certain embodiments; The invention may include other steps after the tube diameter calibration step. (pails) The rolling method according to the invention may include steps for cooling the tube to a temperature

1 room and cut it to specific lengths.

LS aforementioned; The tube diameter calibration step on Jl was not performed with the previous steps

for the method. This means that the tube has moved; During this processing step; with an axial speed that is slower than

It reaches the end of the previous processing steps. Typically; At the end of the preform warming step;

where a greater increase in speed is exposed; The tube travels at a speed of about 1-5 Va s. and is created

0 Calibration of the outside diameter of the tube instead in the range between about 117 m/s and about 7.5 m/s.

According to one embodiment of the method according to the invention; during the calibration step; The tube travels at about 1.0 “dath”.

roll and at that charging speed; The control of the radial position of the volume-defining cylinders is optionally amenable to consideration in real time; The following sectional temperature gauges for the inlet tube and the diameter of the continuous tube. It should be noted that the probability of control; in real time In the movement of cylinders specified 0 of the size dependent on the temperature of the tube means that the differences in temperature along the length of said tube may be managed. In this way a differential setting is no longer required to ensure a uniform duct temperature. In this way it is possible to achieve the Me finish of the tube and thus to obtain the desired diameter in very small tolerances. and the cof shall be noted with the rolling mill and the method according to the invention; 0 gual distribution is likely to be obtained from the reformation Amd) required to produce a beveled tube; compared to the previous field. especially; With reference to the total reshaping required to convert an iron bar into a chamfered tube; The rolling mill and the method according to the previous field use 77650 re-forming in the main rolling mill; 0 Reshaping in the extraction plant; And the remaining 7750 from reshaping in the sizing lab. and on pail) the rolling mill and the method according to invention 710 uses re-forming in the main rolling mill; Te Reformation in the Reduction Lab" and 7100 Reformation Remaining in the Sizer Lab. It should be noted that this redistribution of reshaping is particularly convenient because it greatly increases (from 701 to 77+0) sale] the shaping that occurs immediately in the same primary warming Jane stream; Where the tube is very hot. As it will become clear to those with experience in the field; The rolling mill and the method according to the invention overcome the disadvantages described by reference to the previous field at least partially.

Ya

With respect to embodiments of the plant and method for rolling large-diameter seamless tubes according to the invention; It may be made by those with experience in the field; to fulfill specific requirements; Alterations and/or replacements of items described

Claims (1)

V4 Protection elements included: seamless tube rolling plant Plant - 1 radial position in which the radial position is cmain rolling mill Basic rolling mill - Y semi-finished tube rolling adjustable rolls ¥ ¢ mandrel semifinished tube ¢ placed in the same fixed-roll extraction/reducing mill = ° (Aza and respectively main rolling mill Jaze downstream + semifinished extracting/reducing mill Vv semifinished tube diameter It specifies the diameter of the mandrel tube From the heart of the formation, tube A ¢finished tube, near the predetermined value, at a predetermined value, at a predetermined value, 4 radial, in which the radial position is type sizing mill - 1 sizing mill, and placed cadjustable rolls position 1 1 away from extracting/reducing mill downstream in the same VY stream for it. offline line 10" Extract/jase downstream according to item 10; Also included in the same stream is Plant SS-17 1 tube wall thickness ¥ a means for measuring cextracting/reducing mill reduction ¥ for positioning 1 main rolling mill; The rolling mill designs the semifinished tube V wall thickness measurement, which is based on the rolls of the cylinders' radial position; The radius of the extracting/reducing mill leaving the tube of the pipe wall thickness © to measure means includes a sizing mill and has a sizing mill oY or 1 according to the element Plant? 1 factory for measuring means and means of incoming tube temperature 48 Y 00 It is designed to adjust the half position of the coutgoing tube, the continuous tube, diameter measuring V, temperature measurement based on the rolls measurement of the radial position; Diagonal, which is based on measuring the diameter of the sizing mill entering the work taken in size tube The temperature © sizing mill leaving the size mill finished tube The finished tube diameter 7 Upstream mill Load according to any from the previous items; Including Plant ae = f) and a billet heating plant for heating the furnace “main rolling mill Y longitudinally. billet piercing mill? downstream in the same load stream including AL for any of the elements (Gi, Plant =O) to room temperature tube cooling to cool apparatus lea ¢sizing mill size das) ¥ To cut the tube to predetermined lengths ALE cutting station abd and room temperature station 1 .predetermined lengths ~~ ¢ It is a tube other than tube according to any of the previous items; And in it is the tube, Plant 1-1, that is, emedium-to-large diameter, with a medium-to-large diameter, welded seamless tube of 7 inches (mm) (1 5/8 inches) greater than VIAY diameter ¥ According to any of the previous_items including extraction/_ reduction plant Plant -17 1 fixed rolling stands daily rolling stands daily base 11-8 incl. extracting/reducing mill ¥ aolls 0 incl. sizing mill according to any of the previous elements, so that the plant pias —A 1 with radially adjustable cylinders type rolling stands 1-7 Y radially adjustable rolls ~~ ¥ YY in the extraction/reduction plant cds according to which of the previous_elements; /s.¥,0 =),Y at the tube the sizing mill ¥ moves from the YY (mandrel) of any of the previous elements, so that the formation heart is laa Plant 01-01 Displays sections held so that none of its sectors (01) main rolling mill (Y¢) successive rolling stations. According to any of the aforementioned elements, in which the molding heart is Plant 11-11 and in which there are (77 YY) two portions consisting of two parts (1) the main rolling mill that is connected to any rolling mill a (“YY 77( two portions) joint (FY) joint” A: rolling (¥'¢) rolling station; including the following steps: seamless tube Welded rolling for rolling Method Method 11 - 1 in the mandrel with the forming mold pierced semifinished article rolling semi-finished product - until adjustable rolls are obtained with adjustable cylinders main rolling mill ad ¥ ¢ semifinished tube; On a semi-finished tube ¢ mandrel from the forming core semifinished tube extracting - © to a specified value semifinished tube diameter reducing - 1 ¢predetermined value No prior hd reducing and mandrel reduction, the heart of the formation, extraction, as the extraction steps - A are achieved by a proven reduction / extraction laboratory 815015060 tube The semi-finished tube diameter 4 in the same thread Eada single fixed- roll extracting/reducing mill One dash with a 0 cylinder in series with it; Je main rolling mill downstream 1 YY | 01 = calibrating the tube diameter z to a predetermined value ¢predetermined value IY at which the calibration ¢tube diameter " is obtained 134 - By means of a sizing mill in which the ail radial position 1 of the rolls is adjustable tadjustable 01 0 - in the same stream as the extracting/reduction plant reducing mill 11 - off the line for the extracting/reducing mill 119 - 1 Method according to the previous item; also including the step of measuring thickness VY For tube wall in the same stream as Jess downstream extraction/reduction z? mill -14 1 Method According to item 11 or leds IY Calibrating step Tube diameter VY is performed by adjusting 8 radial positions of the lab rolls ov to take the sizing mill based on measuring 1 temperature of the tube; The tube entering the sizing mill mill 48 and based on the measurement of the measurement diameter © the tube leaving the sizing mill —Yo 1 Method according to any of the elements 11 To (VE included clad before rolling step X pierced semifinished article pierced semifinished article by turning over 001 heating steps ¥ an iron bar billet in a furnace and piercing Iron billet lengthwise ¢ to obtain a pierced semifinished product -11 1 Method according to any of the elements 11 to Vo also included after Bohai calibrating ¥ diameter Diameter of the ctube The steps of cooling the tube to room temperature and cutting it into predetermined lengths.