US20170165729A1 - Compact plant for rolling seamless tubes - Google Patents

Compact plant for rolling seamless tubes Download PDF

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Publication number
US20170165729A1
US20170165729A1 US15/403,420 US201515403420A US2017165729A1 US 20170165729 A1 US20170165729 A1 US 20170165729A1 US 201515403420 A US201515403420 A US 201515403420A US 2017165729 A1 US2017165729 A1 US 2017165729A1
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Prior art keywords
rolling
mandrel
plant
rod
plug
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Abandoned
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US15/403,420
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English (en)
Inventor
Fabio Giovanni Antonio LACAPRUCCIA
Ubaldo Paolo PROVINCIALI
Jacopo Grassino
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SMS Group SpA
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SMS Innse SpA
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Assigned to SMS INNSE S.P.A. reassignment SMS INNSE S.P.A. ASSIGNMENT OF ASSIGNORS INTEREST (SEE DOCUMENT FOR DETAILS). Assignors: GRASSINO, JACOPO, LACAPRUCCIA, Fabio Giovanni Antonio, PROVINCIALI, Ubaldo Paolo
Publication of US20170165729A1 publication Critical patent/US20170165729A1/en
Abandoned legal-status Critical Current

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B17/00—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling
    • B21B17/02—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling with mandrel, i.e. the mandrel rod contacts the rolled tube over the rod length
    • B21B17/04—Tube-rolling by rollers of which the axes are arranged essentially perpendicular to the axis of the work, e.g. "axial" tube-rolling with mandrel, i.e. the mandrel rod contacts the rolled tube over the rod length in a continuous process
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B19/00—Tube-rolling by rollers arranged outside the work and having their axes not perpendicular to the axis of the work
    • B21B19/02—Tube-rolling by rollers arranged outside the work and having their axes not perpendicular to the axis of the work the axes of the rollers being arranged essentially diagonally to the axis of the work, e.g. "cross" tube-rolling ; Diescher mills, Stiefel disc piercers or Stiefel rotary piercers
    • B21B19/04—Rolling basic material of solid, i.e. non-hollow, structure; Piercing, e.g. rotary piercing mills

Definitions

  • the present invention relates to a compact plant for rolling tubes, in particular for rolling seamless tubes.
  • the invention also relates to a method for this rolling operation.
  • a mandrel for the subsequent rolling operation is then inserted inside the pierced blank.
  • the pierced blank is in fact then passed through a multi-stand rolling mill with longitudinal material flow (which will be referred to below as “longitudinal mill”) able to gradually thin the wall through a suitable reduction of the outer diameter, thus increasing the length of the finished product.
  • This rolling mill as is known, comprises a plurality of rolling units. Each unit comprises a stand on which rolls with profiled grooves are mounted. The set of connected profiles of the grooves of the rolls defines the outer profile of the tube released by the rolling unit. Downstream of the longitudinal mill, the tube must be first extracted from the mandrel.
  • this operation is performed by means of another rolling mill which generally has three or more stands, called an extracting mill.
  • the extracting mill performs a small reduction in the outer diameter of the tube, with the main aim of allowing the mandrel to perform the stroke necessary for extraction from the semi-finished tube which has just been produced, also called “mother tube”.
  • the tube must be sized so as to define more precisely its outer diameter.
  • These functions may be performed by a corresponding number of independent machines, called an extracting mill, reducing mill and sizing mill, respectively. More often a single machine may instead perform several functions and thus, for example, the extracting/reducing mill or the reducing/sizing mill is obtained.
  • the tube must only undergo the inspection and/or finishing operations.
  • the inspection operations may consist of pressure tests and checks which are non-destructive, for example using ultrasound.
  • the finishing operations may instead consist of cutting to size, cleaning, painting and marking.
  • the set of operations described above constitutes the core of the tube production process; in fact at the end of these operations the main characteristics of the tube (i.e. the wall thickness and the outer diameter) are defined.
  • the assembly consisting of rotary piercer, longitudinal mill, extracting mill, reducing mill and/or sizing mill defines the main part of the plant, also called technological part.
  • the entire of the layout of the production site, in terms of civil engineering and structural work, must be designed on the basis of the technological part.
  • the apparatus necessary for the inspection and/or finishing operations may be usually arranged without significant constraints around the main part of the plant.
  • transverse flow rolling performed in the piercer
  • longitudinal flow rolling performed in the multi-stand rolling mill
  • the rolling in which the mandrel is retained and extracted on-line immediately downstream of the rolling mill ensures quality of the finished product and reliability far greater than those of other known configurations, in which the mandrel is released and/or free and in which extraction thereof is performed afterwards and off-line.
  • multi-stand longitudinal rolling is suitable for obtaining very high diameter/thickness ratios, where “diameter/thickness ratio” is understood as meaning the ratio between the outer diameter of the tube and the thickness of the tube wall.
  • diameter/thickness ratios obtained by means of multi-stand longitudinal rolling reach values of about 48-50, i.e. much higher than the ratios which may be obtained with other configurations of a different kind, such as that using transverse flow double rolling, where the ratios are generally less than 30-35.
  • the plants of the known type produce so-called double-length semi-finished tubes, i.e. with lengths of up to about 32 metres. Obviously all the dimensions of the plant must be defined on the basis of this final tube size. This size and other parameters are such that, for example, the main building of the production site must have dimensions which exceed the standard market dimensions. Such a building may for example have a main span which is nearly 45 metres and a length which measures more than 900 metres.
  • the transportation of the pierced blank from the piercer to the longitudinal mill may require from 50 to 70 seconds.
  • the pierced blank tends to disperse heat into the environment, thus reaching the longitudinal mill in a substantially colder condition, typically at a temperature of between about 1050° C. and about 1150° C., depending on the form of the said pierced blank.
  • the more the temperature of the pierced blank drops the more the forces which must be applied by the rolling mill increase in order to obtain the desired plastic deformation of the material.
  • the value of the forces to be applied determines the size of the actuators and the motors of the rolling mill, as well as the power consumption of the latter during rolling.
  • the pierced blank is treated internally with anti-oxidising agents, typically borax or substances similar thereto.
  • anti-oxidising agents typically borax or substances similar thereto.
  • the object of the present invention is therefore that of overcoming at least partially the drawbacks mentioned above with reference to the prior art.
  • a task of the present invention is to provide a plant for rolling seamless tubes which may be more compact.
  • a task of the present invention is to provide a plant for the hot rolling of seamless tubes which is sustainable from the environmental point of view, due to the reduction, during the normal production process, of the consumption of electricity and gas, of the emission levels and of the pollutants.
  • a task of the present invention is to provide a compact plant for rolling seamless tubes which allows the negative effects of exposure to air of the pierced blank to be avoided or at least reduced, thus reducing the formation of scale and increasing the yield of the plant.
  • a task of the present invention is to provide a compact plant for the rolling of seamless tubes which requires a smaller initial outlay and which allows the operating costs to be kept low.
  • FIG. 1 shows a plan view diagram of a complete rolling plant according to the prior art
  • FIG. 2 shows, on the same scale as FIG. 1 , a plan view diagram of a complete rolling plant according to the invention
  • FIG. 3 shows the technological part of a plant according to the prior art, indicated by III in FIG. 1 ;
  • FIG. 4 shows, on the same scale as FIG. 3 , the technological part of a plant according to the invention, indicated by IV in FIG. 2 ;
  • FIG. 5 shows a plan view of a plant according to the invention similar to that of FIG. 4 ;
  • FIG. 6 shows a detailed view of the plant part according to the invention indicated by VI in FIG. 5 ;
  • FIG. 7 shows a possible variant of the plant shown in FIG. 6 ;
  • FIG. 8 shows another possible variant of the plant according to FIG. 6 ;
  • FIG. 9 shows a mandrel used in some plants according to the invention.
  • FIG. 10 shows a rod used in some plants according to the invention.
  • FIG. 11 shows a type of mandrel/rod assembly used in some plants according to the invention.
  • FIG. 12 shows another type of mandrel/rod assembly used in some plants according to the invention.
  • the plant for rolling a seamless tube according to the invention is denoted in its entirety by 10 . It comprises:
  • a rolling axis may therefore be specifically defined. “Axial” or “longitudinal” will therefore refer to the direction of a straight line parallel to the axis. Similarly “transverse” will refer to the direction of a straight line not parallel to the axis. Finally “lateral” or “vertical” will refer to the direction of a half line perpendicular to the rolling axis.
  • processing steps define specifically a rolling direction.
  • Expressions such as “before”, “preceding”, “upstream” or the like refer to positions which along the rolling axis are relatively close to the start of the plant.
  • expressions such as “after”, “following”, “downstream” or the like refer to positions which along the rolling axis are relatively close to the end of the plant.
  • the axes of rotation of the rolling rolls are skew.
  • “Skew-axis” is used to define machines in which the rolling rolls have axes which are not parallel to each other and which do not lie in the same plane. These machines are also defined as “transverse rolling” machines.
  • the rolling mill 30 is a machine of the so-called “longitudinal rolling” type in that the axes of the rolling rolls of each stand lie in a same plane which is orthogonal to the rolling axis.
  • the rolling axes X PR and X LL coincide means that the pierced blank 12 output from the rotary piercer 20 may be fed directly to the longitudinal mill 30 , without any need to displace it laterally.
  • the pierced blank 12 still engaged on the rod 24 of the rotary piercer 20 , is brought into the vicinity of the mandrel 32 of the longitudinal mill 30 in a simple and rapid manner.
  • This axial movement may be performed preferably by means of suitable known devices which, by way of a non-exclusive example, may be motor-driven rolls of the pressure type commonly known as “pinch rolls” or of a similar type.
  • the rod 24 at the output of the rotary piercer 20 which is axially aligned with the mandrel 32 , directly comes into contact with the end of the latter.
  • the pierced blank 12 may therefore be slid directly from the rod 24 to the mandrel 32 so that it can be conveyed away for longitudinal rolling.
  • the rod 24 of the rotary piercer 20 is structurally connected to the mandrel 32 of the longitudinal mill 30 .
  • This solution allows the movement of the tooling, i.e. the two tools, to be simplified since during the operational steps they are structurally connected to each other. In this way it is also possible to achieve perfect alignment of the two tools, this allowing the pierced blank 12 to be displaced easily, without the possibility of unexpected difficulties arising.
  • the embodiments of the plant 10 in which the rod 24 is structurally connected to the mandrel 32 may advantageously use two solutions.
  • the rod 24 and the mandrel 32 are made as one piece, while in accordance with a second solution the rod 24 and the mandrel 32 are connected together releasably.
  • Both the solutions have specific advantages and positive features and the choice of one as opposed to the other may be made depending on the specific needs.
  • the rolling plant 10 is preferably designed to roll single-length tubes, namely semi-finished tubes with a length of about 15 metres. Based on this measurement all the main measurements of the plant 10 are defined, as the person skilled in the art may easily understand from the attached FIG. 5 . Considering this final measurement of the tube and the elongation ratios of the various processing steps, it is possible to define a length of about 8 metres for the rod 24 and about 15 metres for the mandrel 32 .
  • the distance between the rotary piercer 20 and the longitudinal mill 30 is greater than the overall length of the aforementioned mandrel/rod assembly 324 and therefore allows easy movement, including lateral movement, of the latter, for example for change-over after rolling or evacuation in the event of an emergency.
  • this tool may have an overall length of less than 25 metres, therefore consistent with the lengths of the mandrels normally used in conventional plants which produce double-length tubes.
  • the mandrel/rod assembly 324 represents a more economical solution than the conventional mandrels which are comparable to it in terms of length and weight.
  • the latter in fact must have a treated surface (for example chrome-plated or with a similar finish) called “noble part” 320 extending over practically their entire external surface.
  • the mandrel/rod assembly 324 on the other hand, must have a treated surface only on the outer surface of the portion which acts as a mandrel 32 , while the portion which acts as a rod 24 does not require any treatment of this kind (see also FIGS. 11 and 12 ).
  • the rod 24 of the plug 22 of the rotary piercer 20 is connected to a thrust block 26 , preferably of the electromechanical type.
  • the thrust block 26 is advantageously positioned downstream of the piercer 20 (see in particular FIG. 6 ). In this way piercing induces in the rod 24 an axial compressive force.
  • This thrust block 26 comprises advantageously a first gripping unit 260 mounted on a first thrust bearing unit 262 .
  • the first gripping unit 260 is above all designed to grip the rod and transfer the axial thrusts to the first thrust bearing unit 262 .
  • the first thrust bearing unit 262 is in turn designed to transmit this thrust to the ground.
  • the thrust/retaining block 26 is also designed to impart to the rod 24 and to the plug 22 the movements which are necessary before and after rolling.
  • the first thrust bearing unit 262 is in fact designed to move the first gripping unit 260 , and along with it the rod 24 and the plug 22 . These movements occur in the axial direction and designed to move the plug 22 from a rest position to a working position and vice versa.
  • the first gripping unit 260 is also designed to impart to the rod 24 and to the plug 22 a pre-rotation about the rolling axis X PR .
  • the possibility of obtaining the pre-rotation of the plug 22 is particularly advantageous in some cases because it allows, in a known manner, piercing of the billets to be facilitated.
  • the mandrel 32 of the longitudinal mill during rolling is connected to a retaining block 34 which is also preferably of the electromechanical type.
  • the retaining block 34 is advantageously positioned upstream of the rolling mill 30 (see in particular FIG. 6 ) so that rolling induces in the mandrel 32 an axial tensile stress.
  • This retaining block 36 comprises advantageously a second gripping unit 340 mounted on a second thrust bearing unit 342 .
  • the retaining block 34 is above all designed to grip the mandrel 32 and to impart to it a predetermined speed during rolling. In fact, during rolling, the rolls of the longitudinal mill 30 push the pierced blank 12 in an axial direction and this transmits the thrust to the mandrel 32 .
  • the mandrel 32 is firmly gripped by the second gripping unit 340 and the axial thrust which is thus generated is transmitted to the second thrust bearing unit 342 .
  • the second thrust bearing unit 342 is in turn designed to transmit this thrust to the ground. If the mandrel 32 were not retained it would be displaced along the longitudinal mill 30 together with the pierced blank 12 . If, on the other hand, the mandrel were retained in a fixed manner, it would remain stationary inside the piece under processing. On the other hand, in this type of plant, the mandrel 32 is braked by the retaining block 34 which imparts to it a predetermined axial speed.
  • the axial speed imparted to the mandrel 32 is preferably greater than 0 mm/s and less than 4000 mm/s.
  • the retaining block 34 is also designed to impart to the mandrel 32 the necessary movements before and after rolling. These movements occur in an axial direction and are intended to move the mandrel 32 from a rest position to a working position and to extract the mandrel 32 from the semi-finished tube 13 released by the longitudinal mill 30 .
  • the first gripping unit 260 for the rod 24 and the second gripping unit 340 for the mandrel 32 could be favourably mounted on a single thrust bearing unit 362 .
  • a thrust/retaining block 36 which combines and replaces the two blocks of the known type would be obtained.
  • the thrust/retaining block 36 therefore, by means of a single system it is possible to manage both the rod 24 of the rotary piercer 20 , i.e. move it and withstand its thrust, and the mandrel 32 of the longitudinal mill 30 , i.e. move and retain it.
  • the thrust/retaining block 36 is advantageously of the electromechanical type. With this solution, in fact, it is possible both to ensure an optimum rigidity of the block and high precision of the movements.
  • the system for moving the thrust bearing unit may consist of a carriage, which is able to move by means of a pinion which meshes along a rack, or of a carriage which is able to move along guides by means of cables or chains.
  • the rolling axes X PR and X LL coincide, by replacing the thrust block 26 and the retaining block 34 with a single thrust/retaining block 36 it is possible to obtain a greater compactness of the plant 10 in the longitudinal direction.
  • the thrust/retaining block 26 is advantageously positioned between the piercer 20 and the rolling mill 30 (see in particular FIGS. 4, 5 and 7, 8 ).
  • a favourable variant of the embodiment of the present invention is one in which the thrust/retaining block 36 , in addition to a single thrust bearing unit 362 , also comprises a single gripping unit 360 .
  • the single gripping unit 360 is designed to grip both the rod 24 and the mandrel 32 and transmit the corresponding axial thrusts to the single thrust bearing unit 362 .
  • This variant improves substantially the mechanical synergy between the components to the advantage of costs, space and cycle times.
  • the single gripping unit 360 is also designed to impart to the rod 24 and to the plug 22 a pre-rotation about the rolling axis X PR .
  • terns suitable systems known per se, called “terns” (not shown in the figures), to constrain the part of the mandrel/rod assembly 324 which during piercing is acted on by compressive loads, so as to prevent buckling, i.e. instability due to axial loading.
  • the terns do not intervene on the noble part 320 of the mandrel/rod assembly 324 which is intended for longitudinal rolling, the surface of this part having been previously treated with lubricant (generally graphite-based) for subsequent longitudinal rolling. Since the terns do not come into contact with this noble part 320 of the mandrel/rod assembly 324 , the lubricant distributed over it remains in good condition until the moment of the rolling operation. This allows on the one hand a good quality of the finished tube to be obtained and on the other hand the noble part 320 of the mandrel to be preserved, increasing consequently its working life.
  • the rod 24 rests axially on the thrust/retaining block 36 intended to transfer the axial thrust exerted by the rolls on the billet 11 and then transmitted from the latter to the plug 22 of the rotary piercer 20 .
  • the first gripping unit 260 and the second gripping unit 340 are removed to allow the axial displacement of the pierced blank 12 engaged on the rod 24 (if the rod 24 is separate from the mandrel 32 ) or of the pierced blank 12 alone (if the rod 24 and mandrel 32 are connected to each other).
  • the retaining block 34 or, if present, the thrust/retaining block 36 is intended to apply a tractional force on the mandrel 32 so as to impart to the latter a predetermined axial speed during rolling in the longitudinal mill 30 .
  • the person skilled in the art may certainly understand how the simple axial displacement of the pierced blank 12 reduces to a minimum its movement and, along with it, its transfer time. More particularly, the transfer time of the pierced blank 12 from the outlet of the rotary piercer 20 to the inlet of the longitudinal mill 30 is thus limited to only about 15 seconds, compared to the about 50-70 seconds which are needed in the known plants. During this short time period the pierced blank 12 disperses much less heat into the environment, thus reaching the longitudinal mill 30 in a substantially hotter condition, typically at a temperature of between about 1210° C. and about 1240° C., depending on the form of the said pierced blank 12 .
  • the fact that the pierced blank 12 is displaced directly from the rod 24 to the mandrel 32 (or even more simply is displaced along the mandrel/rod assembly 324 ) prevents its internal cavity from being filled with ambient air and from being subject to oxidation. In this way it is avoided having to perform known anti-oxidising treatments, which are typically borax-based.
  • the rotary piercer 20 may be a piercer with barrel rolls or a piercer with conical rolls. Both the solutions, which are not described here because they are well-known to the person skilled in the art, have specific advantages and positive features and the choice of one as opposed to the other may be made depending on the specific needs.
  • the longitudinal mill 30 may also be designed with forms which differ slightly.
  • this rolling mill has advantageously the rolls movable radially in order to adjust the position thereof and therefore the force applied during rolling, resulting in the formation of the semi-finished tube 13 from the pierced blank 12 .
  • the longitudinal mill 30 is of the type comprising two rolls for each rolling station.
  • This type of longitudinal mill is particularly compact, reliable and low-cost. According to this type of rolling mill, for example, since the two rolls of each station are operated by the same motor, it is sufficient to use a number of motors equal to the number of rolling stations contained therein. This obviously results in advantages in terms of initial cost, operating consumption, complexity (which is lower) and overall reliability.
  • the longitudinal mill 30 is of the type comprising three rolls for each rolling station.
  • This type of longitudinal mill is particularly precise and suitable for the production of high-quality tubes.
  • the three rolls of each station manage to transmit the deformation force in a particularly regular manner onto the outer profile of the tube. This clearly results in advantages in terms of quality of the end product.
  • both the solutions which are not described here because they are well-known to the person skilled in the art, have specific advantages and positive features and the choice of one as opposed to the other may be performed depending on the specific needs.
  • the plant 10 according to the invention also comprises an operating fork 40 for extracting the mandrel 32 from the semi-finished tube 13 .
  • This operating fork is positioned immediately downstream of the longitudinal mill 30 and is designed to replace the extractor mill present in conventional plants.
  • the longitudinal mill imparts to the tube a significant axial speed, while the mandrel 32 contained inside it is retained by the retaining block 34 upstream. This results in relative sliding of tube 13 and mandrel 32 , so that they are almost entirely extracted.
  • the operating fork 40 retains it in position and the mandrel 32 may be extracted backwards by applying a sufficient axial tractional force via the retaining block 34 or the thrust/retaining block 36 .
  • the mandrel 32 After extraction from the semi-finished tube 13 , the mandrel 32 must undergo a series of treatments so that it may be available for use again.
  • the treatments consist mainly of a suitable cooling and surface treatment with lubricant, which is typically graphite-based. Special stations intended for these treatments are positioned alongside the rolling plant 10 .
  • the plant 10 according to the invention may also comprise a stretch-reducing mill 50 , whereby said mill may be advantageously preceded by a small induction furnace 60 .
  • the stretch-reducing mill 50 is designed to receive at its inlet the semi-finished tube 13 and to release the finished tube 14 , at least depending on its main characteristics (i.e. thickness of the wall and the outer diameter). Downstream of the stretch-reducing mill 50 , the finished tube 14 may if necessary undergo other secondary operations, such as inspection and/or finishing operations.
  • the presence of the induction furnace 60 immediately upstream of the stretch-reducing mill 50 may be advantageous if in that position of the plant 10 there is a reduction in the temperature of the semi-finished tube 13 .
  • this reduction in temperature should be avoided or kept at a negligible level, but in some particular cases the use of the induction furnace 60 could however be advantageous.
  • the temperature required for rolling in the stretch-reducing mill 50 could be advantageously raised in order to reduce the rolling stresses.
  • raising of the temperature during this step could be advantageous in the case of tubes with a particularly thin wall which are more exposed to cooling during the—albeit—small movements.
  • the induction furnace 60 constitutes a particularly compact and simple solution for dealing with the need to raise the temperature of semi-finished tube 13 .
  • This furnace in fact has particularly small dimensions since it is formed simply by a short tunnel inside which the semi-finished tube 13 is axially displaced.
  • Special circuits create induction currents in the metal mass of the tube and these currents determine heating thereof.
  • the stretch-reducing mill 50 may be replaced by a sizing mill.
  • the choice of one as opposed to the other solution may be made on the basis of the specific needs such as the size of the final tube, without adversely affecting the advantages of the invention.
  • the rolling plant 10 according to the invention also comprises a series of escape ways which prove to be particularly advantageous in emergency conditions, namely when there is a malfunction in the rolling process.
  • a first escape way 71 is situated alongside the path for feeding the billet 11 to the rotary piercer 20 .
  • This escape way 71 may be used to discard a billet 11 which is ready for rolling, in the event of a problem of any kind occurring along the rolling line. In this case, in fact, it is not possible to feed the billet to the piercer 20 because the downstream plant may not receive other parts before the current problem is resolved.
  • a first emergency fork may be advantageously used, said fork being designed to keep the billet 11 in position, while the rod 24 and the plug 22 are extracted forwards.
  • the forwards extraction of the plug 22 and the rod 24 is performed by means of the thrust block 26 or, if present, the thrust/retaining block 36 .
  • the only partially pierced billet 11 may then be removed laterally or vertically, for example by means of a crane, while the rod 24 and the plug 22 may be removed by means of the normal lateral exit system, used after rolling.
  • the two parts together may be fed forwards, downstream of the piercer 20 , and discharged laterally.
  • One possible lateral exit is the normal exit path of the mandrel 32 , in particular if the rod 24 and the mandrel 32 are structurally connected together.
  • Another possible escape way is vertical and is made possible by a crane which may raise the assembly consisting of the billet 11 and the rod 24 inserted inside it, thus removing them from the rolling line. The further operations needed to remove the plug 22 from the billet 11 may at this point be duly performed off-line, in the manner known per se.
  • a second escape way 72 and a third escape way 73 are arranged in the vicinity of the outlet for the semi-finished tube 13 from the longitudinal mill 30 .
  • the pierced blank 12 may still be extracted from the mandrel 32 by displacing the latter backwards. In this condition, therefore, the only partially rolled pierced blank 12 may be moved forwards downstream of the longitudinal mill 30 and from here discharged laterally into the second escape way 72 .
  • the operating fork 40 or a second emergency fork 42 situated immediately upstream of the longitudinal mill 30 and designed to keep the pierced blank 12 in position, while the mandrel 32 is extracted backwards.
  • the backwards extraction of the mandrel 32 is performed by means of the thrust/retaining block 36 .
  • the two parts must be fed further forwards downstream of the longitudinal mill 30 , along the third escape way 73 which forms essentially an extension of the outlet of the longitudinal mill 30 .
  • the rolling rolls of the stands of the longitudinal mill 30 are positioned outside of the overall volume by means of the adjustment devices which are normally used during rolling, so as to allow the pierced blank 12 and the mandrel 32 inserted inside it to pass through.
  • the further operations needed to remove the mandrel 32 from the pierced blank 12 may at this point be duly performed off-line, in the manner known per se.
  • the invention also relates to a method for rolling a seamless tube.
  • the method according to the invention comprises the steps of:
  • the rolling axes X PR and X LL coincide.
  • the rolling plant and method according to the invention overcome at least partially the drawbacks identified with reference to the prior art.
  • the power consumption during normal operation may be reduced.
  • rolling of steels with a higher binder content which otherwise could not be processed is possible with the plant according to the invention.
  • the characteristic features of the invention enable a particularly compact rolling plant 10 to be obtained.
  • the main building of the production site may have much smaller dimensions.
  • the width of the plant according to the invention is 30% smaller than that of a conventional plant, while the length is 60% smaller.
  • a prefabricated beamwork and overhead crane may be used for the span of about 30 metres present in a plant according to the invention, thus allowing considerable savings compared to the special reinforced overhead cranes needed for spans for example of 45 metres or more.
  • the area occupied by the plant according to the invention is reduced by 50% compared to a conventional plant.
  • Another particularly advantageous aspect is the possibility of eliminating completely the borax-based deoxidation treatments. In this way, not only the costs associated with the provision and use of the treatment station are avoided, but also the use of toxic substances is eliminated, with a consequent reduced environmental impact. A more rapid transfer of the pierced blank 12 is also obtained, this being particularly advantageous for heat-related reasons in the case of a pierced blank 12 which is particularly thin and therefore subject to more rapid cooling.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Metal Rolling (AREA)
  • Physical Vapour Deposition (AREA)
  • Control Of Metal Rolling (AREA)
  • Grinding Of Cylindrical And Plane Surfaces (AREA)
US15/403,420 2014-07-31 2015-07-09 Compact plant for rolling seamless tubes Abandoned US20170165729A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
ITMI20141399 2014-07-31
ITMI2014A001399 2014-07-31
PCT/IB2015/055193 WO2016016751A1 (fr) 2014-07-31 2015-07-09 Installation compacte pour le laminage de tubes sans soudure

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US (1) US20170165729A1 (fr)
EP (1) EP3174649A1 (fr)
JP (1) JP2017522191A (fr)
CN (1) CN106660087A (fr)
AR (1) AR101373A1 (fr)
RU (1) RU2017106031A (fr)
WO (1) WO2016016751A1 (fr)

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CN120901089A (zh) * 2025-08-14 2025-11-07 山西钰轩机械重工制造有限公司 一种穿孔机顶杆预旋转装置

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WO2016016751A1 (fr) 2016-02-04
AR101373A1 (es) 2016-12-14
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