EP0904859A1 - Verfahren zur Erzeugung günstiger Restspannungen in Schienen oder Tägern - Google Patents

Verfahren zur Erzeugung günstiger Restspannungen in Schienen oder Tägern Download PDF

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Publication number
EP0904859A1
EP0904859A1 EP98307112A EP98307112A EP0904859A1 EP 0904859 A1 EP0904859 A1 EP 0904859A1 EP 98307112 A EP98307112 A EP 98307112A EP 98307112 A EP98307112 A EP 98307112A EP 0904859 A1 EP0904859 A1 EP 0904859A1
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EP
European Patent Office
Prior art keywords
head
foot
force
web
transverse
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Withdrawn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
EP98307112A
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English (en)
French (fr)
Inventor
Alick Henville Priest
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.)
Corus UK Ltd
Original Assignee
British Steel PLC
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
Priority claimed from GBGB9720370.7A external-priority patent/GB9720370D0/en
Application filed by British Steel PLC filed Critical British Steel PLC
Publication of EP0904859A1 publication Critical patent/EP0904859A1/de
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D7/00—Modifying the physical properties of iron or steel by deformation
    • C21D7/02—Modifying the physical properties of iron or steel by deformation by cold working
    • 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
    • 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
    • B21B1/088—H- or I-sections
    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
    • C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
    • C21D9/04—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails

Definitions

  • the present invention relates to sectional elements.
  • it is concerned with the residual stress state of sectional elements, and the means by which a beneficial residual stress state may be achieved.
  • the sectional elements to which the present invention finds particular (but not exclusive) application are rails and I-beams.
  • sectional elements consist of a central portion, at either end of which is an element of greater lateral dimension.
  • I-beam or H-beam these are the upper and lower flanges.
  • foot and the head In a rail section they are asymmetric and referred to as the foot and the head.
  • web, head and foot will be used but it should be understood that these refer to the corresponding sections of an I-beam or any other sectional element to which the invention is applicable.
  • Such sections have a longitudinal axis, i.e. the axis running parallel to the length of the element, and a transverse axis, i.e. a direction running perpendicular to the longitudinal direction in the direction from the head to the foot or vice-versa.
  • the remaining direction, the through-thickness axis, is rarely the subject of a residual stress, at least in the web, as the material is relatively thin.
  • a common test for rail sections is to cut a "crack" of predetermined length into the web in a longitudinal direction.
  • the degree of opening 20 of the crack is then measured to indicate the degree of residual stress. This measurement is referred to as the "Web Saw Opening” or WSO.
  • both rails and other beams experience compressive transverse stresses in the web and tensile longitudinal stresses in the head and foot.
  • these stresses arise as a locomotive travels over that section of rail.
  • I-beam they occur as the beam is subjected to a bending moment around its through-thickness axis. These will clearly add to the existing residual stresses.
  • the longitudinal tension in the head and foot will then contribute to fatigue damage and crack opening of the top and (particularly) bottom surface.
  • the present invention therefore proposes a method of introducing a desired longitudinal residual stress in to a section of the type defined which comprises the application of a force in the transverse or through-thickness direction to a selected sub-element of the section sufficient to produce a strain in that direction and thereby produce a plastic Poisson strain in the longitudinal direction in the selected sub-element, and the removal of the force thereby to leave a residual stress.
  • the method will clearly introduce a further residual stress, and the final residual stress will be the algebraic sum of the original and the introduced stresses.
  • the present invention proposes a method of processing a section of the type defined that comprises the application of a force in the transverse or through-thickness direction thereby to produce a strain in that direction that results in a Poisson strain in the longitudinal direction of the opposite sign to a required change in longitudinal residual stress.
  • the present invention proposes a method of processing a section of the type defined that comprises the application of a quasi-static force in the transverse or through-thickness direction to a selected sub-element of the section thereby to produce a strain in that direction in that sub-element giving rise to a simultaneous Poisson strain in the longitudinal direction having an opposite nature to that of a desired longitudinal residual stress in that selected sub-element of the section.
  • the longitudinal Poisson strain is in general approximately equal to the transverse strain multiplied by minus Poisson's ratio.
  • the selected sub-element is the web.
  • One way of achieving this is to place the web in transverse tension. This can suitably be achieved by exerting an upward force to the lower faces of the head and a downward force to the upper faces of the foot. This is effectively an opening force in the gap between the head and foot. This imparts a transverse tensile stress in the web, which provokes a longitudinal compressive stress. A high enough longitudinal compressive stress, when released, leaves a longitudinal tensile residual stress.
  • a preferred method of achieving this is by the insertion of a wedging element in the region adjacent the web between the head and foot elements thereby to impart to the head and foot a transverse expansion force. Preferably, this is carried out on both sides of the element.
  • the wedging elements can be rollers or elongate static members arranged to form a vise. It is preferred that the wedging elements do not contact the web.
  • Figure 3 shows an embodiment of the present invention applied to a rail.
  • a pair of rollers 50 are provided, which are generally disc-shaped and are rotatable about axis 52.
  • the axial faces 54 of the rollers 50 are inclined at an angle of one in four such that the thickness of the roller 50 decreases with increasing distance from the axis 52.
  • the rollers 50 are applied either side of a rail 60, in this case of the dimensions set down in A.R.E.A. Standard 136RE.
  • the rail 60 is then drawn in the direction of arrow 56 (fig. 4), and the rollers 50 are allowed to rotate about their axis 52.
  • the rollers may be free to rotate or they may be driven.
  • a suitable dimension for the roller involves a minimum width between the outside faces of 122mm, and a depth of at least 75mm. The result of these dimensions is that as the rail passes into the gap between the rollers, the head 62 and foot 64 are forced apart, placing the web 66 in transverse tension.
  • Figure 5 shows schematically an alternative means for imposing a suitable mechanical deformation on the rail 60.
  • a pair of sealing glands 100, 102 are placed either side of the rail 60 such as to contact the head 62 and foot 64 in a sealing manner.
  • a high pressure hydraulic liquid such as oil is then injected into the longitudinal gaps 106 and 108. This exerts a transverse expansion force on the lower faces of the head 62 and upper faces of the foot 64, producing a desirable residual stress state as detailed above.
  • FIG. 6 A further alternative embodiment is illustrated in Figure 6.
  • the rail 60 is subjected to a stress state similar to that of Figures 3 and 4.
  • Upper and lower braces 120 and 122 are provided, each of which is generally U-shaped and is adapted to envelop either the head 62 or foot 64 of the rail.
  • Each carries an axle 124 disposed in a through-thickness direction, and carrying at its free end a roller 126 which contacts a surface of the head 62 or foot 64.
  • the four rollers 126 in total contact the rail 60 on the same faces contacted by the roller 50 of Figures 3 and 4.
  • the braces 120, 122 are then pulled in the transverse direction, exerting a stress state on the rail 60 identical to that of Figures 3 and 4.
  • FIG 7 shows how the arrangement of Figures 3 and 4 can be applied to an I-beam rather than a rail.
  • Rollers 150 correspond generally to the rollers 50 of Figure 3, but differ in their exact dimensions so as to cater for dimensions of the I-beam 160.
  • the I-beam consists of a central web 166, from either end of which extend a head 162 and a foot 164.
  • Four formers 168 are placed in each of the four internal corners of the I-beam, i.e. at the junctions of the web 166 and the head 162 and the foot 164.
  • These formers 168 are generally in the form of a substantially right-angled prism which therefore fits neatly into the corner. They each present an oblique face 170 to the oblique surface 154 of the roller, and therefore allow a smooth wedging action without distorting the I-beam.
  • the formers 168 could of course be dispensed with and the rollers 150 shaped appropriately. However, it is believed that this arrangement provides superior results.
  • FIG 8 shows an alternative construction, applied to a rail 60, in which a pair of static formers 200 are provided alongside the web 66 and between the head 62 and foot 64.
  • Each former 200 consists of a central axis bar 202, and a pair of wedges 204.
  • the wedges 204 are initially at an oblique angle to each other, thereby allowing the former 200 to fit in the space otherwise occupied by the rollers 50.
  • Each wedge 204 can rotate outwardly about the axis bar 202, thereby exerting an opening force to the rail as required. This rotation of the wedges 204 is achieved by compressing the combination of rail 60 and formers 200 on either side thereof, for example between a pair of rollers. Thus, the wedges 204 rotate outwardly and exert the necessary force.
  • Figures 9 to 11 show the results of an experimental embodiment of the invention.
  • planar wedges of the dimensions discussed in relation to the rollers 50 of Figure 3 were forced into the gap between the head and foot of a 136RE rail.
  • the web thickness of the rail is 17.5mm and the web yield stress was determined as 450MPa.
  • This rail was known to have high residual stresses, with a WSO value of about 6mm.
  • the formers were 80mm thick and were laterally compressed into the gap between the head and the base so that a wedging action was produced.
  • the slope of the bottom of the head and top of the base is 1:4 so that (neglecting friction) a given lateral compression force should produce a transverse tensile force four times higher.
  • the forces were applied in line with a set of strain gauges used to measure the longitudinal (horizontal) and transverse (vertical) stresses. The results of the stresses are shown in Figure 9, in the vertical and horizontal directions. The elastic slope is also indicated, with a noted departure from elasticity in the horizontal direction at a vertical stress of less than 450MPa.
  • the stress appears to be more compressive which is the opposite to that desired.
  • the apparent stress registered by the gauge is due to plastic strain.
  • the residual stress is actually related to the difference between the on load and the off load apparent stress at position 0 mm which is positive and therefore in tension. If this longitudinal tension had not been present the apparent stress would have been more in compression than it is and close to the difference of about -400MPa between the elastic slope and the horizontal stress at a force of 1030 kN in Figure 9.
  • the change in residual stress is therefore an increase in tension of about 300 MPa which is a desirable result.
  • Figure 11 is a line drawing depiction of a 136RE rail which was left untreated in a first region X but subjected to the above experimental treatment over region Y. It can be seen visually that the Web Saw Opening value had decreased significantly, in fact from above 4mm to less than 1 mm.
  • Figure 12 shows comparative results for rails treated according to a variety of methods. The longitudinal residual stress is shown for the head, web and foot of each rail.
  • the treatment methods were as follows:
  • the rail treated according to the invention is left in a state of residual compression in the base, an area particularly prone to fatigue damage. No other process achieved this.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Metal Rolling (AREA)
  • Machines For Laying And Maintaining Railways (AREA)
EP98307112A 1997-09-26 1998-09-04 Verfahren zur Erzeugung günstiger Restspannungen in Schienen oder Tägern Withdrawn EP0904859A1 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GBGB9720370.7A GB9720370D0 (en) 1997-09-26 1997-09-26 Sectional elements
GB9720370 1997-09-26
GB9722357 1997-10-24
GB9722357A GB2329650A (en) 1997-09-26 1997-10-24 Stressing of sectional elements

Publications (1)

Publication Number Publication Date
EP0904859A1 true EP0904859A1 (de) 1999-03-31

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Family Applications (1)

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EP98307112A Withdrawn EP0904859A1 (de) 1997-09-26 1998-09-04 Verfahren zur Erzeugung günstiger Restspannungen in Schienen oder Tägern

Country Status (3)

Country Link
EP (1) EP0904859A1 (de)
JP (1) JPH11156438A (de)
CA (1) CA2248429A1 (de)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2518207C1 (ru) * 2012-11-23 2014-06-10 Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Уральский федеральный университет имени первого Президента России Б.Н. Ельцина" Способ термической обработки рельсов

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS558317A (en) * 1978-07-03 1980-01-21 Nippon Steel Corp Residual stress reducing method of h-beam
DE3223346A1 (de) * 1982-02-19 1983-09-01 Sacilor S.A., 57704 Hayange Verfahren zum richten von eisenbahnschienen und durch das verfahren hergestellte eisenbahnschienen
DE3529379A1 (de) * 1984-11-02 1986-07-10 Krupp Stahl Ag, 4630 Bochum Verfahren zum erhoehen der ermuedungsfestigkeit von schienen
JPH06279846A (ja) * 1993-03-29 1994-10-04 Nippon Steel Corp レール腹部、耐脆性き裂進展特性の優れたレール
JPH06306802A (ja) * 1993-04-26 1994-11-01 Nippon Steel Corp 耐内部損傷性に優れたレール
JPH06312217A (ja) * 1993-04-30 1994-11-08 Nippon Steel Corp 耐内部損傷性の優れたレールの製造法
JPH07185659A (ja) * 1993-12-27 1995-07-25 Nippon Steel Corp 耐疲労性、耐脆性破壊性レールの形状矯正装置
DE19633758C1 (de) * 1996-08-22 1997-09-11 Thyssen Stahl Ag Verfahren zur Verringerung der Aufklaffwerte im Stegeinsägeversuch von Eisenbahnschienen aus Stahl

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS558317A (en) * 1978-07-03 1980-01-21 Nippon Steel Corp Residual stress reducing method of h-beam
DE3223346A1 (de) * 1982-02-19 1983-09-01 Sacilor S.A., 57704 Hayange Verfahren zum richten von eisenbahnschienen und durch das verfahren hergestellte eisenbahnschienen
DE3529379A1 (de) * 1984-11-02 1986-07-10 Krupp Stahl Ag, 4630 Bochum Verfahren zum erhoehen der ermuedungsfestigkeit von schienen
JPH06279846A (ja) * 1993-03-29 1994-10-04 Nippon Steel Corp レール腹部、耐脆性き裂進展特性の優れたレール
JPH06306802A (ja) * 1993-04-26 1994-11-01 Nippon Steel Corp 耐内部損傷性に優れたレール
JPH06312217A (ja) * 1993-04-30 1994-11-08 Nippon Steel Corp 耐内部損傷性の優れたレールの製造法
JPH07185659A (ja) * 1993-12-27 1995-07-25 Nippon Steel Corp 耐疲労性、耐脆性破壊性レールの形状矯正装置
DE19633758C1 (de) * 1996-08-22 1997-09-11 Thyssen Stahl Ag Verfahren zur Verringerung der Aufklaffwerte im Stegeinsägeversuch von Eisenbahnschienen aus Stahl

Non-Patent Citations (4)

* Cited by examiner, † Cited by third party
Title
PATENT ABSTRACTS OF JAPAN vol. 004, no. 033 (M - 003) 21 March 1980 (1980-03-21) *
PATENT ABSTRACTS OF JAPAN vol. 095, no. 001 28 February 1995 (1995-02-28) *
PATENT ABSTRACTS OF JAPAN vol. 095, no. 002 31 March 1995 (1995-03-31) *
PATENT ABSTRACTS OF JAPAN vol. 095, no. 010 30 November 1995 (1995-11-30) *

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
RU2518207C1 (ru) * 2012-11-23 2014-06-10 Федеральное государственное автономное образовательное учреждение высшего профессионального образования "Уральский федеральный университет имени первого Президента России Б.Н. Ельцина" Способ термической обработки рельсов

Also Published As

Publication number Publication date
CA2248429A1 (en) 1999-03-26
JPH11156438A (ja) 1999-06-15

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