EP0807692A1 - Method of cooling structural steel beams - Google Patents
Method of cooling structural steel beams Download PDFInfo
- Publication number
- EP0807692A1 EP0807692A1 EP97106855A EP97106855A EP0807692A1 EP 0807692 A1 EP0807692 A1 EP 0807692A1 EP 97106855 A EP97106855 A EP 97106855A EP 97106855 A EP97106855 A EP 97106855A EP 0807692 A1 EP0807692 A1 EP 0807692A1
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- EP
- European Patent Office
- Prior art keywords
- cooling
- profile
- temperature
- water
- steel
- 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.)
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- 238000001816 cooling Methods 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims abstract description 22
- 229910000746 Structural steel Inorganic materials 0.000 title 1
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 22
- 239000010959 steel Substances 0.000 claims abstract description 22
- 230000008569 process Effects 0.000 claims abstract description 12
- 238000005096 rolling process Methods 0.000 claims abstract description 12
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 8
- 238000006243 chemical reaction Methods 0.000 claims description 7
- 239000000463 material Substances 0.000 claims description 7
- 230000035508 accumulation Effects 0.000 claims description 3
- 238000009825 accumulation Methods 0.000 claims description 3
- 239000000498 cooling water Substances 0.000 claims description 2
- 230000007704 transition Effects 0.000 abstract description 5
- 238000009826 distribution Methods 0.000 description 15
- 239000000835 fiber Substances 0.000 description 9
- 230000009466 transformation Effects 0.000 description 6
- 241001136792 Alle Species 0.000 description 1
- 240000003517 Elaeocarpus dentatus Species 0.000 description 1
- 230000006978 adaptation Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- JZQOJFLIJNRDHK-CMDGGOBGSA-N alpha-irone Chemical compound CC1CC=C(C)C(\C=C\C(C)=O)C1(C)C JZQOJFLIJNRDHK-CMDGGOBGSA-N 0.000 description 1
- 238000005452 bending Methods 0.000 description 1
- 230000008602 contraction Effects 0.000 description 1
- 238000003754 machining Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000007246 mechanism Effects 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 238000012805 post-processing Methods 0.000 description 1
- 230000036316 preload Effects 0.000 description 1
- 238000001953 recrystallisation Methods 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 230000000930 thermomechanical effect Effects 0.000 description 1
- 238000011144 upstream manufacturing Methods 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B37/00—Control devices or methods specially adapted for metal-rolling mills or the work produced thereby
- B21B37/28—Control of flatness or profile during rolling of strip, sheets or plates
- B21B37/44—Control of flatness or profile during rolling of strip, sheets or plates using heating, lubricating or water-spray cooling of the product
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B38/00—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product
- B21B38/006—Methods or devices for measuring, detecting or monitoring specially adapted for metal-rolling mills, e.g. position detection, inspection of the product for measuring temperature
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
- B21B45/0203—Cooling
- B21B45/0209—Cooling devices, e.g. using gaseous coolants
- B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
-
- 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
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/84—Controlled slow cooling
-
- 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
- C21D9/0068—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for particular articles not mentioned below
-
- 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
- C21D9/06—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for rails with diminished tendency to become wavy
-
- 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
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B21—MECHANICAL METAL-WORKING WITHOUT ESSENTIALLY REMOVING MATERIAL; PUNCHING METAL
- B21B—ROLLING OF METAL
- B21B45/00—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills
- B21B45/02—Devices for surface or other treatment of work, specially combined with or arranged in, or specially adapted for use in connection with, metal-rolling mills for lubricating, cooling, or cleaning
- B21B45/0203—Cooling
- B21B45/0209—Cooling devices, e.g. using gaseous coolants
- B21B45/0215—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes
- B21B2045/0221—Cooling devices, e.g. using gaseous coolants using liquid coolants, e.g. for sections, for tubes for structural sections, e.g. H-beams
Definitions
- the invention relates to a method for cooling shaped steel, in particular section steel beams from the rolling heat.
- the cooling of shaped steel, such as section steel beams, eg double T and U profiles, angles, T steels, after the rolling is usually done with the help of a cooling bed. Because of the uncontrolled, often unfavorable, free cooling of the section steel beams or bars during the dwell time on the cooling bed, an adverse influence on the straightness and the internal stress state is inevitable. The straightness or the natural shape is causally closely related to the residual stress state. Taken together, these two quality criteria mentioned for the section steel beams can be compared with the flatness of the strip rolling.
- the invention is based on the following considerations and knowledge relating to the mechanism of the generation of residual stresses.
- a rolled section steel beam leaves the last rolling stand in good approximation with a homogeneous distribution of strain, which means that the beam or rod is straight and has no areas with waviness.
- the rod / support is also almost free of residual stress due to the high temperature level.
- the rolling rod takes on a shape due to the distortion that occurs, in which the internal moment becomes zero, unless external forces - e.g. Weight, friction or other holding forces, for example due to a straightening grate - prevent it.
- external forces e.g. Weight, friction or other holding forces, for example due to a straightening grate - prevent it.
- the invention has for its object to provide a method which enables a profile steel having a uniform temperature distribution towards the end of the conversion.
- a final air cooling is preceded by a targeted water cooling in such a way that shaped steel areas having material accumulations are cooled on the outside of the profile with a variable exposure width and duration subject to a computer-aided predetermined cooling strategy, down to a value which is at least just above the conversion temperature Arl will.
- the areas on the outside of the profile are, for example, the flanges for double T and U profiles.
- the appropriate temperature distribution is preferably set by rows of spray nozzles arranged one behind the other in the rolling direction, which, depending on the requirements, can also be arranged several times next to one another and possibly nested, with different spacings in the longitudinal direction or as different nozzles which act on the profile at the desired points or areas.
- the temperature of the shaped steel is determined in order to determine the exposure width and duration as well as the intensity necessary for the cooling strategy and is entered into the process computer.
- the temperature distribution in the profile is determined at the beginning of the cooling process or in the case of continuous systems before the profile enters the cooling section. This determination can be achieved either by measuring the temperatures of different profile areas, by measuring a reference temperature and drawing conclusions about a characteristic distribution, by calculation taking into account the forming history, or as a combination of these methods.
- the suitable cooling strategy is then determined with the help of the process computer, the cooling process automatically in due time activated, if necessary changes in speed or temperature changes over the length and finally ended.
- the calculation of the suitable cooling strategy can either be achieved on-line using software based on a physical model, or calculation results can be determined in advance depending on the profile type, assumed temperature distributions and material off-line, implemented in the computer and the cooling intensity and duration be determined interpolatively.
- a water cooling section following the last rolling mill necessary for the rolling of the shaped steel is preferably subdivided into individually controllable and switchable or switchable cooling zones, an adaptation to different profiles, temperature situations, materials and speeds of the outgoing can be carried out in a simple manner Reach shape steel.
- the cooling section can consist of several cooling section sections. A sufficient number of individually controllable zones also enables the process to be controlled in the event of changing conditions, such as the throughput speed or the output temperature distribution, and also a standstill, e.g. of the rod end within the cooling section can then be controlled.
- the size of the water-pressurized steel surface be changed by changing the distance from the cooling water nozzles to the profile outside and, according to a further proposal of the invention, the cooling intensity is controlled by changes in the supply pressure.
- the manifolds it is advisable to equip the manifolds with several rows of nozzles instead of just one row of nozzles on each side, which contributes to widening the exposure area and grading the cooling intensity.
- the position or the course of the cooled web defined by the impinging water jets on the shaped steel can be adjusted by means of a corresponding device via rotatable rows of nozzles.
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Materials Engineering (AREA)
- Thermal Sciences (AREA)
- Crystallography & Structural Chemistry (AREA)
- Physics & Mathematics (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Metal Rolling (AREA)
- Heat Treatments In General, Especially Conveying And Cooling (AREA)
- Control Of Metal Rolling (AREA)
- Control Of Heat Treatment Processes (AREA)
Abstract
Description
Die Erfindung betrifft ein Verfahren zum Kühlen von Formstahl, insbesondere Profilstahlträgern aus der Walzhitze.The invention relates to a method for cooling shaped steel, in particular section steel beams from the rolling heat.
Das Kühlen von Formstahl, wie Profilstahl-Träger, z.B. Doppel-T-und U-Profile, Winkel, T-Stähle, nach dem Walzen geschieht üblicherweise mit Hilfe eines Kühlbettes. Aufgrund der während der Verweildauer auf dem Kühlbett unkontrollierten, oft ungünstigen freien Abkühlung der Profilstahl-Träger bzw. Stäbe ist meist ein nachteiliger Einfluß auf die, Geradheit und den Eigenspannungszustand unvermeidlich. Die Geradheit bzw. die Eigenform hängt nämlich ursächlich eng mit dem Eigenspannungszustand zusammen. Diese beiden für die Profilstahl-Träger genannten Qualitätskriterien gemeinsam genommen lassen sich mit der Planheit bei der Bandwalzung vergleichen. Während bei Bändern die Bedeutung einer guten Planlage jedoch überwiegend unter geometrischen Aspekten zu sehen ist, wirken sich Längenunterschiede der Fasern über dem Querschnitt bei vergleichsweise steifen Profilen nur gegebenenfalls als Krümmung, mit Sicherheit aber als eine unter Umständen erhebliche Reduzierung der Tragfähigkeit aufgrund von Eigenspannungen aus. Neben einer verminderten Tragfähigkeit bei einwirkenden äußeren Lasten weisen eigenspannungsbehaftete Bauteile auch einen größeren Verzug bei der Bearbeitung aufgrund der dabei entstehenden Störung des Gleichgewichtszustandes auf und neigen auch eher zur Rißbildung in Bereichen mit großen Eigenspannungsunterschieden, wie sie insbesondere im Übergangsbereich vom Steg zum Flansch auftreten können, beispielsweise bei Doppel-T-Profilen.The cooling of shaped steel, such as section steel beams, eg double T and U profiles, angles, T steels, after the rolling is usually done with the help of a cooling bed. Because of the uncontrolled, often unfavorable, free cooling of the section steel beams or bars during the dwell time on the cooling bed, an adverse influence on the straightness and the internal stress state is inevitable. The straightness or the natural shape is causally closely related to the residual stress state. Taken together, these two quality criteria mentioned for the section steel beams can be compared with the flatness of the strip rolling. While the importance of good flatness for hinges can mainly be seen from a geometrical point of view, differences in length of the fibers across the cross-section only have a curvature in comparatively stiff profiles, but certainly a considerable reduction in the load-bearing capacity due to residual stresses. In addition to a reduced load-bearing capacity with external loads acting on them, components subject to internal stress also have a greater distortion during machining due to the resulting disturbance of the state of equilibrium and also tend to form cracks in areas with large internal stress differences, as can occur in particular in the transition area from the web to the flange. for example with double-T profiles.
Der Erfindung liegen die folgenden, den Mechanismus des Entstehens von Eigenspannungen betreffenden Überlegungen und Kenntnisse zugrunde. Ein gewalzter Profilstahl-Träger verläßt das letzte Walzgerüst in guter Näherung mit einer homogenen Dehnungsverteilung, was bedeutet, daß der Träger bzw. Stab gerade ist und keine Bereiche mit Welligkeit aufweist. Im Falle von dynamisch rekristallisierenden Werkstoffen ist der Stab/Träger aufgrund des hohen Temperaturniveaus auch nahezu eigenspannungsfrei. Hingegen stellt sich bei einer unterdrückten dynamischen Rekristallisation - eine wichtige Voraussetzung für das thermomechanische Walzen - eine für die letzten Stichabnahmen charakteristische Eigenspannungssituation ein.The invention is based on the following considerations and knowledge relating to the mechanism of the generation of residual stresses. A rolled section steel beam leaves the last rolling stand in good approximation with a homogeneous distribution of strain, which means that the beam or rod is straight and has no areas with waviness. In the case of dynamically recrystallizing materials, the rod / support is also almost free of residual stress due to the high temperature level. On the other hand, with suppressed dynamic recrystallization - an important prerequisite for thermomechanical rolling - there is a residual stress characteristic that is characteristic of the last pass.
Die Temperaturverteilung nach der letzten Walzung ist üblicherweise deutlich inhomogen; insbesondere an Stellen mit einer Materialanhäufung kühlt ein Profil weniger stark ab als in dünnwandigen Bereichen. Unabhängig davon, wie der thermische Ausgangszustand war, kühlt ein Profil an Luft im allgemeinen inhomogen ab. Die dadurch bedingten unterschiedlichen thermischen Längenänderungen müssen durch elastische oder sogar elastischplastische Dehnungen kompensiert werden, begleitet durch den Aufbau von damit unvermeidlich einhergehenden Spannungen. Je höher die Temperatur ist, desto schneller bauen sich derartige Spannungen durch Relaxation ab, d.h. einem mit einer parallel ablaufenden Spannungsarmglühung vergleichbarem Vorgang. Da dies allerdings langsamer abläuft als die thermischen Veränderungen, wird das Profil auch in dieser Phase hoher Temperaturen in Summe durch innere Spannungen belastet. Bei unsymmetrischen Abkühlbedingungen oder Profilgeometrien nimmt der Walzstab bedingt durch den auftretenden Verzug eine Form an, bei der das innere Moment zu Null wird, es sei denn, daß äußere Kräfte - z.B. Gewichts-, Reibungs- oder andere Haltekräfte, beispielsweise aufgrund eines Richtrostes - ihn daran hindern.The temperature distribution after the last rolling is usually clearly inhomogeneous; A profile cools less strongly than in thin-walled areas, especially in places with material accumulation. Regardless of what the initial thermal state was, a profile in air generally cools inhomogeneously. The resulting different thermal changes in length must be compensated for by elastic or even elastic-plastic strains, accompanied by the build-up of the inevitable associated stresses. The higher the temperature, the faster such stresses dissipate through relaxation, i.e. a process comparable to a stress relieving process running in parallel. However, since this takes place more slowly than the thermal changes, the profile is also burdened by internal stresses in this phase of high temperatures. With asymmetrical cooling conditions or profile geometries, the rolling rod takes on a shape due to the distortion that occurs, in which the internal moment becomes zero, unless external forces - e.g. Weight, friction or other holding forces, for example due to a straightening grate - prevent it.
Gerät eine Faser oder ein Teil des Profiles in den Bereich der Gamma-Alpha-Gefügeumwandlung, so baut sich dort aufgrund der völligen Neustrukturierung des Gefüges jegliche Spannung ab. Auch das durch die geringere Packungsdichte des Alpha-Eisens bedingte Wachsen dieser Faser wird zum Teil unterdrückt, weil sich die anderen, noch nicht in der Umwandlung befindlichen Fasern aufgrund ihrer Restelastizität gegen ein Mitwachsen wehren. In dieser Phase des sukzessiven Erreichens des Umwandlungsbereiches verändert sich die Krümmung eines unsymmetrischen oder unsymmetrisch abkühlenden und nicht in einem Richtrost oder anderweitig geführten Profiles ständig. Erst gegen Ende der Umwandlung ist das Profil nahezu eigenspannungsfrei und unabhängig von dem sich frei ausbildenden oder erzwungenen Krümmungszustand. Dann allerdings, wenn mindestens zwei Fasern oder Teilbereiche die untere Grenztemperatur der Umwandlung unterschritten haben, kann sich zwischen diesen Fasern wieder ein Zwang ergeben, der eine Folge des elastischen bzw. elastisch-plastischen Ausgleichs unterschiedlicher thermisch bedingter Kontraktionen ist. Diese Spannungen - spätere Eigenspannungen - werden unterhalb der Umwandlung wegen der dann zunehmend unbedeutender werdenden Relaxation auch kaum noch abgebaut. Mit fortschreitender Abkühlung verlassen mehr und mehr Fasern den Bereich der Umwandlung und beteiligen sich an dem oben beschriebenen Aufbau der Eigenspannungen.If a fiber or part of the profile gets into the area of the gamma-alpha microstructure transformation, any tension will be released there due to the complete restructuring of the microstructure. The growth of this fiber caused by the lower packing density of alpha iron is also partly suppressed because the other fibers, which are not yet in the process of transformation, resist resisting growth due to their residual elasticity. In this phase of successively reaching the conversion area, the curvature of an asymmetrical or asymmetrically cooling profile that is not in a straightening grate or otherwise guided profile changes constantly. Only towards the end of the transformation is the profile almost free of residual stress and independent of the freely developing or forced state of curvature. However, if at least two fibers or partial areas have fallen below the lower limit temperature of the conversion, a constraint can arise between these fibers, which is a result of the elastic or elastic-plastic compensation of different thermally induced contractions. These stresses - later residual stresses - are hardly reduced below the transformation because of the then increasingly insignificant relaxation. As cooling progresses, more and more fibers leave the area of transformation and participate in the build-up of residual stresses described above.
Der Erfindung liegt die Aufgabe zugrunde, ein Verfahren zu schaffen, das einen gegen Ende der Umwandlung eine gleichförmige Temperaturverteilung aufweisenden Profilstahl ermöglicht.The invention has for its object to provide a method which enables a profile steel having a uniform temperature distribution towards the end of the conversion.
Diese Aufgabe wird erfindungsgemäß dadurch gelöst, daß einer abschließenden Luftkühlung eine gezielte Wasserkühlung vorgeschaltet wird, derart, daß Materialanhäufungen aufweisende Formstahlbereiche profilaußenseitig mit einer einer rechnergestützt vorgegebenen Kühlstrategie unterliegenden, variablen Beaufschlagungsbreite und -dauer bis auf einen zumindest noch knapp oberhalb der Umwandlungstemperatur Arl liegenden Wert gekühlt werden. Die profilaußenseitigen Bereiche sind z.B. die Flansche bei Doppel-T- und U-Profilen. Indem somit durch eine selektive Kühlung oberhalb der Umwandlungstemperatur Arl, vorzugsweise an der Grenze der unteren Umwandlungstemperatur, eine homogene Temperaturverteilung ermöglicht wird, weil der Träger nach der Wasserkühlung sich selbst überlassen wird, bis die gekühlten Bereiche den Kühlvorrat aufgezehrt und sich thermisch wieder erholt haben, liegt ein technisch eigenspannungsfreies Profil vor. Es kommt daher nicht mehr wie bei den bekannten Verfahren zu einem Aufbau innerer Spannungen im Profil, die dort aufgrund im wesentlichen elastischer bzw. elastisch-plastischer Kompensation unterschiedlicher, thermisch bedingter Dehnungen infolge einer inhomogenen Temperaturverteilung gegen Ende der Umwandlung auftreten. Es wird somit die Formstabilität sowohl bei der Herstellung der Profilstahl-Träger als auch bei deren Nachbearbeitung, z. B. Sägen, verbessert. Die weitgehende Eigenspannungsarmut gegen Ende der Umwandlung in Verbindung mit einer gleichförmigen Temperaturverteilung führt selbst dann zu einem nahezu eigenspannungsfreien und somit höher belastbaren und formstabilen Profil - auch nach vollständiger Abkühlung auf Raumtemperatur - ,wenn die Temperaturverteilung zwischenzeitlich inhomogen war.This object is achieved according to the invention in that a final air cooling is preceded by a targeted water cooling in such a way that shaped steel areas having material accumulations are cooled on the outside of the profile with a variable exposure width and duration subject to a computer-aided predetermined cooling strategy, down to a value which is at least just above the conversion temperature Arl will. The areas on the outside of the profile are, for example, the flanges for double T and U profiles. Thus, by selective cooling above the transition temperature Arl, preferably at the limit of the lower transition temperature, a homogeneous temperature distribution is made possible because the carrier is left to cool down after the water cooling until the cooled areas have the cooling supply have consumed and recovered thermally, there is a technically residual stress-free profile. Therefore, as in the known methods, there is no longer any build-up of internal stresses in the profile, which occur due to essentially elastic or elastic-plastic compensation of different, thermally-induced expansions due to an inhomogeneous temperature distribution towards the end of the conversion. It is thus the dimensional stability both in the manufacture of the section steel beams and in their post-processing, eg. B. saws, improved. The extensive low residual stress towards the end of the transformation in connection with a uniform temperature distribution leads to an almost residual stress-free and thus more resilient and dimensionally stable profile - even after complete cooling to room temperature - if the temperature distribution has been inhomogeneous in the meantime.
Die Einstellung der geeigneten Temperaturverteilung erfolgt vorzugsweise durch in Walzrichtung hintereinander angeordnete Spritzdüsenreihen, die entsprechend den Erfordernissen auch mehrfach nebeneinander und gegebenenfalls verschachtelt, mit unterschiedlichen Abständen in Längsrichtung oder als unterschiedliche Düsen ausgeführt sein können, die das Profil an den gewünschten Stellen bzw. Bereichen beaufschlagen.The appropriate temperature distribution is preferably set by rows of spray nozzles arranged one behind the other in the rolling direction, which, depending on the requirements, can also be arranged several times next to one another and possibly nested, with different spacings in the longitudinal direction or as different nozzles which act on the profile at the desired points or areas.
Nach einem Vorschlag der Erfindung wird zur Bestimmung der für die Kühlstrategie notwendigen Beaufschlagungsbreite und -dauer sowie Intensität die Temperatur des Formstahles ermittelt und in den Prozeßrechner eingegeben. Hierzu wird zu Beginn des Kühlvorganges bzw. bei Durchlaufanlagen vor dem Eintritt des Profils in die Kühlstrecke die Temperaturverteilung im Profil ermittelt. Diese Ermittlung läßt sich entweder durch Messung der Temperaturen verschiedener Profilbereiche, durch Messung einer Referenztemperatur und Rückschluß auf eine charakteristische Verteilung, durch Berechnung unter Berücksichtigung der umformtechnischen Vorgeschichte oder als Kombination dieser Verfahren erreichen. Anhand dieser Eingaben wird anschließend die geeignete Kühlstrategie mit Hilfe des Prozeßrechners ermittelt, der Kühlvorgang zeitgerecht automatisch aktiviert, bei Geschwindigkeitsänderungen oder Temperaturveränderungen über der Länge gegebenenfalls variiert und schließlich beendet. Die Berechnung der geeigneten Kühlstrategie läßt sich mit Hilfe einer auf einem physikalischen Modell basierenden Software entweder on-line erreichen, oder es können im Vorfeld Berechnungsergebnisse abhängig vom Profiltyp, angenommenen Temperaturverteilungen und Werkstoff off-line ermittelt, im Rechner implementiert und die Kühlintensität und -dauer interpolativ ermittelt werden.According to a proposal of the invention, the temperature of the shaped steel is determined in order to determine the exposure width and duration as well as the intensity necessary for the cooling strategy and is entered into the process computer. For this purpose, the temperature distribution in the profile is determined at the beginning of the cooling process or in the case of continuous systems before the profile enters the cooling section. This determination can be achieved either by measuring the temperatures of different profile areas, by measuring a reference temperature and drawing conclusions about a characteristic distribution, by calculation taking into account the forming history, or as a combination of these methods. Based on these inputs, the suitable cooling strategy is then determined with the help of the process computer, the cooling process automatically in due time activated, if necessary changes in speed or temperature changes over the length and finally ended. The calculation of the suitable cooling strategy can either be achieved on-line using software based on a physical model, or calculation results can be determined in advance depending on the profile type, assumed temperature distributions and material off-line, implemented in the computer and the cooling intensity and duration be determined interpolatively.
Wenn eine dem letzten für die Walzung des Formstahles notwendigen Walzwerk nachfolgende Wasserkühlstrecke, insbesondere eine Durchlaufkühlstrecke, vorzugsweise in einzeln ansteuerbare und abschalt- bzw. zuschaltbare Kühlzonen unterteilt wird, läßt sich in einfacher Weise eine Anpassung an unterschiedliche Profile, Temperatursituationen, Werkstoffe und Geschwindigkeiten des auslaufenden Formstahles erreichen. Hierbei kann die Kühlstrecke aus mehreren Kühlstreckenabschnitten bestehen. Eine hinreichende Anzahl einzeln ansteuerbarer Zonen ermöglicht darüber hinaus auch die Steuerung des Prozesses bei sich verändernden Bedingungen, wie der Durchlaufgeschwindigkeit oder der Ausgangstemperaturverteilung, und auch ein Stillstand, z.B. des Stabendes, innerhalb der Kühlstrecke ist dann beherrschbar.If a water cooling section following the last rolling mill necessary for the rolling of the shaped steel, in particular a continuous cooling section, is preferably subdivided into individually controllable and switchable or switchable cooling zones, an adaptation to different profiles, temperature situations, materials and speeds of the outgoing can be carried out in a simple manner Reach shape steel. The cooling section can consist of several cooling section sections. A sufficient number of individually controllable zones also enables the process to be controlled in the event of changing conditions, such as the throughput speed or the output temperature distribution, and also a standstill, e.g. of the rod end within the cooling section can then be controlled.
Es wird vorgeschlagen, daß die Größe der wasserbeaufschlagten Formstahlfläche durch Verändern des Abstandes von Kühlwasser-Düsen zur Profilaußenseite verändert und nach einem weiteren Vorschlag der Erfindung die Kühlintensität durch Änderungen des Versorgungsdruckes gesteuert wird. Vor allem bei größeren Profilen empfiehlt es sich, statt in Laufrichtung pro Seite nur einer Düsenreihe eine Bestückung der Verteilerrohre mit mehreren Düsenreihen vorzunehmen, was zur Verbreiterung der Beaufschlagungsfläche und zur Stufung der Kühlintensität beiträgt. Die Lage bzw. der Verlauf der durch die auftreffenden Wasserstrahlen definierten, gekühlten Bahn am Formstahl kann aufgrund einer entsprechenden Vorrichtung über drehbare Düsenreihen eingestellt werden.It is proposed that the size of the water-pressurized steel surface be changed by changing the distance from the cooling water nozzles to the profile outside and, according to a further proposal of the invention, the cooling intensity is controlled by changes in the supply pressure. Especially in the case of larger profiles, it is advisable to equip the manifolds with several rows of nozzles instead of just one row of nozzles on each side, which contributes to widening the exposure area and grading the cooling intensity. The position or the course of the cooled web defined by the impinging water jets on the shaped steel can be adjusted by means of a corresponding device via rotatable rows of nozzles.
Die Wirkungsweise des erfindungsgemäßen Verfahrens im Vergleich zum Stand der Technik veranschaulichen die beiden nachfolgend einander gegenübergestellten Beispiele:
- 1. Abkühlung eines Profiles HEB 140 an der Luft nach dem Stand der Technik
Ausgehend von einer homogenen Anfangstemperaturverteilung von T0=900°C und dem Werkstoff c 45, liegt aufgrund der freien Abkühlung nach dem Unterschreiten der unteren Umwandlungstemperatur durch die heißeste Faser eine Eigenspannungen hervorrufende inhomogene Temperatur- bzw. Zwischentemperaturverteilung vor, die nach vollständiger Abkühlung auf Raumtemperatur (300 Minuten) Restspannungen bewirkt. Hierbei treten Eigenspannungen in Höhe von ca. 21% der Kaltfließgrenze von 460 N/mm2 unter anderem an den Flanschspitzen auf, d.h. unabhängig von der Biegeachse an den Außenfasern, die im Falle aufzunehmender äußerer Lasten grundsätzlich höchstbelastet sind. Diese Vorbelastung durch Restspannungen reduziert die Belastbarkeit des fertigen Trägers ganz erheblich. - 2. Abkühlung eines Profiles HEB 140 an der Luft nach einer vorgeschalteten, erfindungsgemäßen Wasserkühlung
Werden nun bei gleichen Voraussetzungen wie oben genannt die Flanschaußenseiten für die Dauer von 6,7 sec auf einer 80 mm breiten, mittigen Bahn mit richtig bemessener Intensität wassergekühlt, läßt sich nach vollständigem Durchlaufen der Umwandlung eine wesentlich gleichmäßigere Temperaturverteilung erreichen, was Versuche bestätigt haben. Nach vollständiger Abkühlung ergeben sich Eigenspannungen, die maximal nur noch 5,6% der Kaltfließgrenze betragen. Darüber hinaus ergibt sich eine deutliche Vergleichmäßigung der Spannungen, insbesondere im Wurzelbereich, in dem bei nach üblicher Praxis abgekühlten Profilen häufig eigenspannungsbedingte Anrisse auftreten. Für die Berechnung des Zusammenhangs zwischen Spannungen und Dehnungen werden neben den thermisch bedingten Längenänderungen alle anderen kontinuumsmechanisch relevanten Vorgänge berücksichtigt, wie Elastizität, Plastizität und Relaxation in Abhängigkeit von der Temperatur.
- 1. Cooling of a profile HEB 140 in air according to the state of the art
Assuming a homogeneous initial temperature distribution of T 0 = 900 ° C and the material c 45, due to the free cooling after the lower transition temperature has been exceeded by the hottest fiber, there is an inhomogeneous temperature or intermediate temperature distribution causing internal stresses, which after complete cooling to room temperature (300 minutes) causes residual tension. Here, internal stresses in the amount of approx. 21% of the cold yield point of 460 N / mm 2 occur, among other things, at the flange tips, ie independent of the bending axis on the outer fibers, which are generally highly stressed in the event of external loads to be absorbed. This preload due to residual stresses considerably reduces the resilience of the finished beam. - 2. Cooling of a profile HEB 140 in air after an upstream water cooling according to the invention
If, with the same conditions as mentioned above, the flange outer sides are water-cooled for a period of 6.7 seconds on a 80 mm wide, central web with the correct intensity, a much more uniform temperature distribution can be achieved after the conversion has been completed, which tests have confirmed. After complete cooling, residual stresses arise, which are a maximum of only 5.6% of the cold yield point. In addition, there is a clear equalization of the stresses, particularly in the root area, in which cracks often occur due to inherent stresses in profiles that have cooled down according to customary practice. In addition to the thermally induced changes in length, all others are used to calculate the relationship between stresses and strains Processes relevant to continuum mechanics are taken into account, such as elasticity, plasticity and relaxation depending on the temperature.
Claims (5)
dadurch gekennzeichnet,
daß einer abschließenden Luftkühlung eine gezielte Wasserkühlung vorgeschaltet wird, derart, daß Materialanhäufungen aufweisende Formstahl profilaußenseitig mit einer einer rechnergestützt vorgegebenen Kühlstrategie unterliegenden, variablen Beaufschlagungsbreite und -dauer bis auf einen zumindest noch knapp oberhalb der Umwandlungstemperatur Arl liegenden Wert gekühlt werden.Process for cooling shaped steel, in particular section steel beams, from the rolling heat,
characterized,
that a final air cooling is preceded by a targeted water cooling, in such a way that molded steel having material accumulations is cooled on the outside of the profile with a variable exposure width and duration subject to a computer-aided predetermined cooling strategy to a value that is at least just above the conversion temperature Arl.
dadurch gekennzeichnet,
daß zur Bestimmung der für die Kühlstrategie notwendigen Beaufschlagungsbreite und -dauer sowie Intensität die Temperatur des Formstahles ermittelt und in den Prozeßrechner eingegeben wird.Method according to claim 1,
characterized,
that to determine the exposure width and duration and intensity required for the cooling strategy, the temperature of the shaped steel is determined and entered into the process computer.
dadurch gekennzeichnet,
daß die Größe der wasserbeaufschlagten Formstahlfläche durch Verändern des Abstandes von Kühlwasser-Düsen zur Profilaußenseite verändert wird.The method of claim 1 or 2,
characterized,
that the size of the water-pressurized steel surface is changed by changing the distance from the cooling water nozzles to the outside of the profile.
dadurch gekennzeichnet,
daß die Kühlintensität durch Änderungen des Versorgungsdruckes gesteuert wird.Method according to one of claims 1 to 3,
characterized,
that the cooling intensity is controlled by changes in the supply pressure.
dadurch gekennzeichnet,
daß die Wasserkühlstrecke in einzeln ansteuerbare und abschalt- bzw. zuschaltbare KÜhlzonen unterteilt wird.Method according to one of claims 1 to 4,
characterized,
that the water cooling section is divided into individually controllable and switchable or switchable cooling zones.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19619574 | 1996-05-15 | ||
| DE19619574 | 1996-05-15 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| EP0807692A1 true EP0807692A1 (en) | 1997-11-19 |
Family
ID=7794382
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP97106855A Withdrawn EP0807692A1 (en) | 1996-05-15 | 1997-04-25 | Method of cooling structural steel beams |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US6059903A (en) |
| EP (1) | EP0807692A1 (en) |
| JP (1) | JPH1071415A (en) |
| KR (1) | KR970073769A (en) |
| CN (1) | CN1171307A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1111074A3 (en) * | 1999-12-23 | 2004-01-07 | SMS Demag AG | Method and device for cooling hot-rolled profiles |
Families Citing this family (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH11221742A (en) * | 1997-09-30 | 1999-08-17 | Hoya Corp | Grinding method, grinding device, glass substrate for magnetic recording medium and magnetic recording medium |
| DE19828785C2 (en) * | 1998-06-27 | 2000-08-03 | Sms Demag Ag | Process for straightening rolled section steel |
| US7073805B2 (en) * | 2003-01-06 | 2006-07-11 | Hui Yan | User-propelled riding toys and methods |
| CN102601305B (en) * | 2012-03-26 | 2013-11-20 | 大连远东美连精工有限公司 | Investment casting method by use of entity shell making |
| NZ610739A (en) * | 2012-05-18 | 2014-04-30 | Neturen Co Ltd | Rebar structure and reinforced concrete member |
| CN103042054A (en) * | 2013-01-25 | 2013-04-17 | 中冶赛迪工程技术股份有限公司 | Cooling and bending preventing device for specially-shaped steel and process method |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE404127C (en) * | 1924-02-16 | 1924-10-13 | Cie Des Forges De Chatillon Co | Process for straightening metal bars of asymmetrical cross-section, in particular on railroad tracks |
| DE2148722A1 (en) * | 1970-10-02 | 1972-05-10 | Wendel Sidelor | Process for the heat treatment of rails with a high resistance to wear and the rails produced thereby |
| US4486248A (en) * | 1982-08-05 | 1984-12-04 | The Algoma Steel Corporation Limited | Method for the production of improved railway rails by accelerated cooling in line with the production rolling mill |
| EP0151194A1 (en) * | 1984-01-28 | 1985-08-14 | VEB Stahl- und Walzwerk "Wilhelm Florin" Hennigsdorf | Method of improving the evenness of rolled steel |
| US4668308A (en) * | 1984-05-09 | 1987-05-26 | Centre De Recherches Metallurgiques-Centrum Voor Research In De Metallurgie | Method and apparatus for manufacturing rails |
| US5000798A (en) * | 1989-11-07 | 1991-03-19 | The Algoma Steel Corporation, Limited | Method for shape control of rail during accelerated cooling |
| DE4237991A1 (en) * | 1992-11-11 | 1994-05-19 | Schloemann Siemag Ag | Cooling hot-rolled products, rails - using appts. with carrier elements allowing rails to be suspended with their top downwards |
| EP0725152A1 (en) * | 1995-02-04 | 1996-08-07 | Sms Schloemann-Siemag Aktiengesellschaft | Method and device for cooling hot-rolled profiles |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS60197825A (en) * | 1984-03-19 | 1985-10-07 | Yokogawa Hokushin Electric Corp | Cooling control method |
| DE69113326T2 (en) * | 1990-06-21 | 1996-03-28 | Nippon Steel Corp | Method and device for producing steel double-T beams with a thin web. |
| JPH04103720A (en) * | 1990-08-21 | 1992-04-06 | Kawasaki Steel Corp | Production of h section steel with superior shape |
| CH686072A5 (en) * | 1992-06-19 | 1995-12-29 | Alusuisse Lonza Services Ag | Spray system for Kuhlen profiles. |
-
1997
- 1997-04-25 EP EP97106855A patent/EP0807692A1/en not_active Withdrawn
- 1997-05-09 US US08/853,615 patent/US6059903A/en not_active Expired - Fee Related
- 1997-05-10 KR KR1019970018047A patent/KR970073769A/en not_active Withdrawn
- 1997-05-14 JP JP9124500A patent/JPH1071415A/en not_active Withdrawn
- 1997-05-15 CN CN97111199A patent/CN1171307A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE404127C (en) * | 1924-02-16 | 1924-10-13 | Cie Des Forges De Chatillon Co | Process for straightening metal bars of asymmetrical cross-section, in particular on railroad tracks |
| DE2148722A1 (en) * | 1970-10-02 | 1972-05-10 | Wendel Sidelor | Process for the heat treatment of rails with a high resistance to wear and the rails produced thereby |
| US4486248A (en) * | 1982-08-05 | 1984-12-04 | The Algoma Steel Corporation Limited | Method for the production of improved railway rails by accelerated cooling in line with the production rolling mill |
| EP0151194A1 (en) * | 1984-01-28 | 1985-08-14 | VEB Stahl- und Walzwerk "Wilhelm Florin" Hennigsdorf | Method of improving the evenness of rolled steel |
| US4668308A (en) * | 1984-05-09 | 1987-05-26 | Centre De Recherches Metallurgiques-Centrum Voor Research In De Metallurgie | Method and apparatus for manufacturing rails |
| US5000798A (en) * | 1989-11-07 | 1991-03-19 | The Algoma Steel Corporation, Limited | Method for shape control of rail during accelerated cooling |
| DE4237991A1 (en) * | 1992-11-11 | 1994-05-19 | Schloemann Siemag Ag | Cooling hot-rolled products, rails - using appts. with carrier elements allowing rails to be suspended with their top downwards |
| EP0725152A1 (en) * | 1995-02-04 | 1996-08-07 | Sms Schloemann-Siemag Aktiengesellschaft | Method and device for cooling hot-rolled profiles |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1111074A3 (en) * | 1999-12-23 | 2004-01-07 | SMS Demag AG | Method and device for cooling hot-rolled profiles |
Also Published As
| Publication number | Publication date |
|---|---|
| CN1171307A (en) | 1998-01-28 |
| KR970073769A (en) | 1997-12-10 |
| JPH1071415A (en) | 1998-03-17 |
| US6059903A (en) | 2000-05-09 |
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