EP2504112A2 - Procédé de laminage de rails, dispositif de laminage de rails et rail produit selon ledit procédé - Google Patents

Procédé de laminage de rails, dispositif de laminage de rails et rail produit selon ledit procédé

Info

Publication number
EP2504112A2
EP2504112A2 EP10787018A EP10787018A EP2504112A2 EP 2504112 A2 EP2504112 A2 EP 2504112A2 EP 10787018 A EP10787018 A EP 10787018A EP 10787018 A EP10787018 A EP 10787018A EP 2504112 A2 EP2504112 A2 EP 2504112A2
Authority
EP
European Patent Office
Prior art keywords
rail
blank
head
worked
mill
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP10787018A
Other languages
German (de)
English (en)
Inventor
Damian Gerard Shipton
Darren Michael Norfolk
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tata Steel UK Ltd
Original Assignee
Tata Steel UK Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tata Steel UK Ltd filed Critical Tata Steel UK Ltd
Priority to EP10787018A priority Critical patent/EP2504112A2/fr
Publication of EP2504112A2 publication Critical patent/EP2504112A2/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B1/00—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations
    • B21B1/08—Metal-rolling methods or mills for making semi-finished products of solid or profiled cross-section; Sequence of operations in milling trains; Layout of rolling-mill plant, e.g. grouping of stands; Succession of passes or of sectional pass alternations for rolling structural sections, i.e. work of special cross-section, e.g. angle steel
    • B21B1/085—Rail sections
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
    • B21B—ROLLING OF METAL
    • B21B13/00—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories
    • B21B13/08—Metal-rolling stands, i.e. an assembly composed of a stand frame, rolls, and accessories with differently-directed roll axes, e.g. for the so-called "universal" rolling process

Definitions

  • This invention relates to a method of rolling rails.
  • the invention also relates to an apparatus for carrying out said method, and to a product produced therewith.
  • Rails are formed by three general methods of rolling :
  • the plane of symmetry of the rail coincides with the pass line or is perpendicular thereto.
  • the diagonal or angular method differs from the first method in that the shaping of the rail begins with the first pass in the roughing stand, and instead of first compressing the bloom through a smaller size and then forming the section partly through compression and partly through spreading, the process is one of compression from beginning to end.
  • the universal method employs both horizontal and vertical rolls in one stand to effect shaping of the work piece. In some cases, a semi-universal stand is used comprising two horizontal rolls and one vertical roll. The universal rolling method allows a greater degree of hot working of the head and flange of a rail by compression than can be obtained when horizontal rolls alone are used.
  • the traditional or conventional style of rolling rails is to use horizontal rolls either two-high (i.e. two work rolls) or three-high (i.e. three work rolls) typically in a cross country style mill as disclosed in WO2004/009259.
  • the process comprises the bloom being deformed into a "top hat” before being turned onto its side.
  • This "top hat” can be described as a bar having a trapezoidal cross-section.
  • the tail and head of the bar is subsequently knifed to begin the rolling process where the head portion, web portion and foot portion of the rail are formed.
  • This method is that the deformations of the head and foot portion are relatively low during some of the passes.
  • the conventional universal rulling method also starts by first producing the "top hat", and further using two-high rolls to form the "top hat” pass through knifing into a rail blank shape before completion through universal stands.
  • These universal stands use shaped vertical rolls for the formation of the head and or a combination of open closed grooves of the universal to form the foot. Again the deformations of the head and foot portion are relatively low during some of the passes.
  • the material may be rolled either in a reversible manner rather than one-way only, depending on the set-up and lay-out of the mill.
  • the traditional roughing process requires particular techniques to reduce, twist and turn the bar to manipulate the bar into the correct shape and orientation. Up to 12 to 14 passes must be made through the mill, all of which may or may not be through shaped rolls. Usually the number of roughing stands is small, usually two, wherein the work rolls are provided with several pass grooves for subsequent passes and consequently this first stage of the rail rolling process accounts for a considerable time in the mill.
  • Figure 1 represents a typical example of a cross country style mill.
  • the "top hat” is indicated with the dashed ellipsoid.
  • the current practice for universal rolling contains a number of steps: universal rolling with two horizontals and two verticals of which the roll which forms the head of the rail is shaped to the particular rail profile being rolled; edger rolling, head rolling and foot rolling within separate stands.
  • the greater part of the reductions of the head and foot are typically performed within the universal stands containing two horizontal rolls and two vertical rolls in a thickness orientation around the profile of the rail section.
  • the breakdown workpiece obtained in this method has a larger section that is substantially similar to the desired rail in shape, as shown in Figures 2 and 3.
  • the difference in width between the head and foot must be accomplished in the roughing operation as indicated by the pass grooves on the roughing stands as shown in Figures 2 and 3. This calls for providing many roll passes in the roughing mill.
  • the roughing operation is the bottleneck in the rail rolling process, and it governs the productivity of the universal rail rolling operation as a whole.
  • One or more of the objects are achieved by a method of rolling steel rails comprising :
  • a multi-stand continuous tandem finishing mill comprising at least one horizontal stand (H) followed by at least five four-roll universal stands (U), wherein each universal stand (U x ) only contains flat vertical rolls for forming the lower foot portion (2a) and the head portion (3a) of the rail, and wherein each universal stand (U x ) contains two shaped horizontal rolls for forming the sides (7a, 7b) of the rail and particularly the web portion (4a, 4b) of the rail, wherein the rail blank is passed only once through said finishing mill, and wherein in at least one combination of two subsequent stands U, and U l+ i
  • the rail is worked on the lower foot portion (2a) and not on the head (3a) using the flat vertical rolls in U, and wherein the rail is worked on the head (3a) and not on the lower foot portion (2a) using the flat vertical rolls in U l+i , or o the rail is worked on the head (3a) and not on the lower foot portion (2a) using the flat vertical rolls in U, and wherein the rail is worked on the lower foot portion (2a) and not on the head (3a) using the flat vertical rolls in U
  • a rail blank is transferred to the fully continuous multi-stand finishing mill, preferably consisting of at least five stands.
  • the horizontal stand is the first stand and the universal stands are placed downstream of the horizontal stand when seen in the rolling direction.
  • the stands of the finishing mill are operated in tandem, i.e. after threading the product to be rolled is rolled in all stands at the same time. It is noted that this fully-continuous tandem rolling requires careful choice of the rolling schedule and rolling speeds of the respective stands, because the amount of material passing through each stand must be the same at any given time.
  • At least one of the vertical rolls in the universal stands in the finishing mill comprises a vertical roll for working the head portion of the rail.
  • the blank is brought to a suitable rolling temperature prior to rolling.
  • the reheating temperature for steel rails is chosen such that the finishing temperature (i.e. the temperature at which the last deformation is given) is still in the austenitic range, i.e. above Ar 3 .
  • the rail may be cooled in still air (natural cooling) or in a water spray, mist, forced air, or submersion in a coolant (accelerated cooling). These cooling regimes are known.
  • the terms vertical and horizontal are used to indicate which rolls are meant.
  • the horizontal rolls have a rotational axis which is about horizontal
  • the vertical rolls have a rotational axis which is about perpendicular to the horizontal. All embodiments are described such that the web of the blank is substantially horizontal. It should be pointed out however that the invention could also be performed with the web of the blank in the vertical direction, particularly in the finishing mill.
  • the forging action within the universal stands provides a direct application of pressure on the head portion in the crown area (the surface contacting the wheel of the train when in use), and this prevents the occurrence of rolling imperfections as the rail is reduced to the desired dimensions.
  • the length of the distance between the head crown and the lower portion of the foot is reduced.
  • the foot portion is reduced in the same direction as the head portion as a result of the opposing force exerted by the vertical flat roll which works the foot portion.
  • the head portion is reduced in two directions i.e. crown and sides.
  • the head crown is only worked with very slight force applied in the direction as applied by the universal method.
  • the universal method actively forges the head portion in this invention at least 5 times with direct pressure applied to the head crown in three instances with the vertical rolls.
  • the roll working the head portion in the universal stand arrangement is profiled and shaped to suit each particular section.
  • shaped vertical work rolls mean that the rolls are stand specific.
  • wear of the shaped vertical work roll will affect the surface quality of the head portion of the rail.
  • both the vertical rolls working the foot and head portion are flat. There is no need for shaped vertical, thereby reducing the need for stand specific rolls.
  • maintenance of the vertical rolls is simplified because there is no need to provide them with a contour during grinding of the roll to remove the worn surface. This allows flexibility between not only products but also between stands. It is also cost-efficient.
  • any roll can be chosen for any stand. Also as part of the universal process with flat verticals it may not be necessary to change stands for rolling similar products, whereas with shaped verticals the profile of the crown will change and thus a stand change may be required.
  • the flat vertical work rolls would simply require a change to the schedule settings. This flexibility in using work rolls for various rolling schedules and in different rolling stands saves both time and money. Also better dimensional tolerances of the rails are obtainable.
  • the number of replacement sets of rolls may be reduced.
  • An advantage of the process according to the invention is that surface defects within the head portion are prevented as a result of the increased working of the head in comparison to the known process. As the head undergoes more direct work in the crown area, any potential surface defects caused by rolling are rolled out and hence do not occur in the finished product.
  • the rail is worked on the lower foot portion (2a) and not on the head (3a) using the flat vertical rolls in ⁇ ( and U j and wherein the rail is worked on the head (3a) and not on the lower foot portion (2a) using the flat vertical rolls in U i+ i and U J+ i; or
  • the rail is worked on the head (3a) and not on the lower foot portion (2a) using the flat vertical rolls in U, and U j and wherein the rail is worked on the lower foot portion (2a) and not on the head (3a) using the flat vertical rolls in U l+ i and U J+ i; or o the rail is worked on the head (3a) and not on the lower foot portion (2a) using the flat vertical rolls in U, and U J+ i and wherein the rail is worked on the lower foot portion (2a) and not on the head (3a) using the flat vertical rolls in Ui + i and U j ; or
  • the rail is worked on the head (3a) and not on the lower foot portion (2a) using the flat vertical rolls in U 1+ i and Uj and wherein the rail is worked on the lower foot portion (2a) and not on the head (3a) using the flat vertical rolls in Ui and U J+ i.
  • This embodiment allows to subject the head and foot to an even higher degree of deformation and thus any defects are effectively removed by this method.
  • there can also be more than two combinations e.g. 3 or 4) provided there are enough rolling stands in the finishing mill.
  • the inventors found that two combinations proved to be particularly efficient in producing a high quality rail as a result of a stable thermomechanical process. When using more stands, the temperature control of the material to be rolled becomes more difficult, potentially leading to too low rolling temperatures or potentially necessitating in-line heating equipment.
  • the finishing mill comprises one horizontal stand and six universal stands. It was found that this configuration allows maximum flexibility and throughput.
  • the finishing mill consists of one horizontal stand (HI) and six universal stands (U2 to U7), preferably in the configuration H1-U2-U3-U4-U5-U6-U7.
  • HI horizontal stand
  • U2 to U7 universal stands
  • the rail blank is provided by casting a cast steel rail blank.
  • the rail blank from an alternative source, either in addition to rolled rail blanks, or instead of rolled rail blanks, the dependence on the roughing mills to provide the rail blanks is reduced.
  • the productivity of the finishing mill can hereby be significantly increased.
  • the rail blank may be hot charged into a reheating furnace prior to rolling thereby obtaining a potential energy saving.
  • the cast rail blank may be asymmetrical or symmetrical with respect to the centreline of the web portion of the rail blank.
  • the roughing mill should be understood to comprise a breakdown mill for converting a bloom into a blank with a substantially rectangular cross-section and an intermediate mill for converting the blank into a rail blank.
  • the blank has a substantially square cross-section
  • the cast shape or rectangular or square-shaped blank is taken from the breakdown mill and passed to the intermediate mill where the head and foot will be given different widths and thicknesses formed in the intermediate reversing operation according to the roll-pass design. Accordingly, the rail blank from the intermediate mill resembles the rail to be manufactured in shape, but is larger in dimensions than the finished rail product.
  • the required rectangular or square-shaped blank from the breakdown mill or caster can feed the intermediate mill to produce a rail blank.
  • the square-shaped cast blank may be hot charged into a reheating furnace prior to rolling thereby obtaining a potential energy saving.
  • This process is comparable to the known method for producing rail, albeit that the bloom is not converted into a "top-hat”-configuration but into a substantially square-shaped blank.
  • the blank may also be in a cast form.
  • the roughing mill is a reversing mill.
  • the intermediate mill forms the rectangular blank into a rail blank which is asymmetrical with respect to the centreline of the web portion of the rail blank.
  • the rolled bloom and blank remain substantially symmetrical with respect to the eventual centreline of the web portion of the rail blank throughout the entire rolling process of bloom to finished rail.
  • the advantage of this symmetrical process is that the top and bottom rolls are identical.
  • the last universal stand of the finishing mill is a semi-universal stand consisting of two shaped horizontal rolls for working the head portion and the web portion, one flat vertical roll for working the lower foot portion and one flat vertical dummy roll opposite the flat vertical roll for working the lower foot portion.
  • the dummy roll does not work the head crown of the rail.
  • the final stand is semi-universal and part of the continuous rolling train.
  • the final universal stand rolls the section to the final dimensions as required by the customer.
  • the use of a semi universal stand in the final stand allows the finished products to have excellent tolerance and surface quality around the head and foot of the rail.
  • all universal rolling stands U x can be replaced by semi-universal stands if only the head crown or the lower foot portion is worked.
  • each of the universal stands U3 to U7 may be replaced by semi-universal stands if so desired.
  • all universal stands are full universal stands from a control and power point of view.
  • a rolling mill for rolling rail in accordance with the method described above is provided wherein the rolling mill comprises a multi-stand continuous tandem finishing mill comprising at least one horizontal stand (H) and at least five four-roll universal stands (U), wherein each universal stand (U x ) only contains flat vertical rolls for forming the lower foot portion (2a) and the head portion (3a) of the rail, and wherein each universal stand (U x ) contains two shaped horizontal rolls for forming the sides (6a, 6b) of the rail and particularly the web portion (4a, 4b) of the rail.
  • H horizontal stand
  • U universal stands
  • the substantially rectangular or square shaped cast or rolled blank can be rolled into an H-section or I-section using the same finishing mill not only from the same blank as used for rolling rails but also using the same flat vertical rolls in the four roll universal configuration.
  • the shaped horizontal rolls in the universal stands are exchanged for flat horizontal rolls which perform the forming action of the web of the I-section or H-section. This exchange can be done much more quickly, thus reducing the downtime of the mill. Costs for rolls are also reduced, because the vertical rolls are the same. The mill also has become more flexible.
  • a rail is provided, produced according to the method described above.
  • the final microstructure of the head in the finished rail is finer and the likelihood of defects is further reduced.
  • Figure 1 represents a typical example of a cross country style mill.
  • top hat is indicated with the dashed ellipsoid.
  • Shaped vertical rolls are used for the shaping of the head portion of the rail in U1-U4 and UF.
  • Three edger stands are used in the configuration E2-U1-U3-E1-U2-U4-E3-UF.
  • Figure 2 represents a typical example of a mill using grooves and involving turning actions.
  • the "top hat” is indicated with the dashed ellipsoid.
  • Figure 3 is a schematic representation of the evolution of a blank 1 into a rail.
  • the blank in figure 3a comprises a foot portion 2, a head portion 3 and a web portion 4 connecting the foot portion 2 to the head portion 3.
  • the blank has a symmetrical cross-section with respect to the centreline (dot-dashed line) of the web portion 4.
  • the blank must not necessarily be symmetrical with respect to the line perpendicular to the centreline, although in this case it is.
  • This lower foot portion is the part of the rail which rests on the sleeper or the rail bed.
  • the head crown i.e. the part which eventually comes into contact with the wheels of a train, is indicated with 3a.
  • the edges of the web part are indicated with 4a and 4b, whereas 7a and 7b represent the entire side curvature starting at the head crown, and ending at the lower portion of the foot.
  • 7a and 7b are the parts formed by the horizontal rolls. 4a is therefore a part of 7a.
  • 2a and 3a are the parts formed by the vertical rolls.
  • Figure 4 is a schematic representation of a process according to the invention.
  • the finishing mill is represented which, starting from a rail blank produces a finished rail in a 7-stands continuous tandem mill of a H1-U2-U3-U4-U5-U6-U7, wherein all vertical rolls are flat rolls.
  • the combination of U3 and U4 and the combination of U5 and U6 are the combinations wherein in U3 and U5 only the foot is worked by the flat vertical roll and wherein in U4 and U6 only the head is worked by the flat vertical roll.
  • the horizontal stand the web of the rail is worked.
  • Figure 4b represents the evolution of a square-shaped blank into a rail blank in an intermediate mill
  • Figure 4a represents the evolution of a bloom into an square-shaped blank in a breakdown mill.
  • the breakdown mill and the intermediate mill jointly form the roughing mill.

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Metal Rolling (AREA)

Abstract

La présente invention est relative à un procédé de laminage de rails d'acier, comprenant les étapes suivantes: fournir une ébauche de rail (5), l'ébauche comprenant une partie de pied (2), une partie de tête (3) et une partie d'âme (4) qui relie la partie de pied à la partie de tête; finir l'ébauche de rail pour former un rail d'acier (6) dans un laminoir finisseur tandem à cages multiples comprenant au moins une cage horizontale (H) et au moins cinq cages universelles à quatre cylindres (U), dans lequel chaque cage universelle (Ux) contient uniquement des cylindres verticaux droits pour former la partie de pied inférieure (2a) et la partie de tête (3a) du rail, et dans lequel chaque cage universelle (Ux) contient deux cylindres horizontaux profilés pour former les côtés (6a, 6b) du rail et en particulier la partie d'âme (4a, 4b) du rail, dans lequel l'ébauche de rail est passée une seule fois à travers ledit laminoir finisseur, et dans lequel dans au moins une combinaison de deux cages successives Ul et Ul+1, le rail est travaillé sur le pied et pas sur la tête en utilisant les cylindres verticaux droits dans Ul, et dans lequel le rail est travaillé sur la tête et pas sur le pied en utilisant les cylindres verticaux droits dans Ul+1; ou le rail est travaillé sur la tête et pas sur le pied en utilisant les cylindres verticaux droits dans Ul, et dans lequel le rail est travaillé sur le pied et pas sur la tête en utilisant les cylindres verticaux droits dans Ul+1. L'invention est également relative à un dispositif pour exécuter ledit procédé, et à un produit fabriqué à partir de celui-ci.
EP10787018A 2009-11-26 2010-11-24 Procédé de laminage de rails, dispositif de laminage de rails et rail produit selon ledit procédé Withdrawn EP2504112A2 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
EP10787018A EP2504112A2 (fr) 2009-11-26 2010-11-24 Procédé de laminage de rails, dispositif de laminage de rails et rail produit selon ledit procédé

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
EP09014727 2009-11-26
EP10787018A EP2504112A2 (fr) 2009-11-26 2010-11-24 Procédé de laminage de rails, dispositif de laminage de rails et rail produit selon ledit procédé
PCT/EP2010/007102 WO2011063935A2 (fr) 2009-11-26 2010-11-24 Procédé de laminage de rails, dispositif de laminage de rails et rail produit selon ledit procédé

Publications (1)

Publication Number Publication Date
EP2504112A2 true EP2504112A2 (fr) 2012-10-03

Family

ID=42112298

Family Applications (1)

Application Number Title Priority Date Filing Date
EP10787018A Withdrawn EP2504112A2 (fr) 2009-11-26 2010-11-24 Procédé de laminage de rails, dispositif de laminage de rails et rail produit selon ledit procédé

Country Status (6)

Country Link
EP (1) EP2504112A2 (fr)
AP (1) AP2012006333A0 (fr)
RU (1) RU2012126553A (fr)
UA (1) UA105251C2 (fr)
WO (1) WO2011063935A2 (fr)
ZA (1) ZA201203122B (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107597841A (zh) * 2017-07-28 2018-01-19 包头钢铁（集团）有限责任公司 全万能四辊成品孔型轧制钢轨的方法

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2627140C1 (ru) * 2016-10-10 2017-08-03 Акционерное общество "ЕВРАЗ Объединенный Западно-Сибирский металлургический комбинат", АО "ЕВРАЗ ЗСМК" Способ прокатки рельсов

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5850101A (ja) * 1981-09-22 1983-03-24 Nippon Steel Corp 軌条のユニバ−サル圧延方法
JPS5921403A (ja) * 1982-06-30 1984-02-03 Nippon Steel Corp 軌条のユニバ−サル圧延方法
JPS5921402A (ja) * 1982-06-30 1984-02-03 Nippon Steel Corp 連続ｈ形鋼圧延工程における軌条のユニバ−サル圧延方法
ITMI20021594A1 (it) * 2002-07-19 2004-01-19 Danieli Off Mecc Metodo e impianto per la laminazione a caldo di rotaie

Non-Patent Citations (1)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN107597841A (zh) * 2017-07-28 2018-01-19 包头钢铁（集团）有限责任公司 全万能四辊成品孔型轧制钢轨的方法

Also Published As

Publication number Publication date
WO2011063935A3 (fr) 2011-11-24
AP2012006333A0 (en) 2012-06-30
RU2012126553A (ru) 2014-01-10
WO2011063935A2 (fr) 2011-06-03
ZA201203122B (en) 2013-06-26
UA105251C2 (ru) 2014-04-25

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