WO2001087518A1 - Procede et installation de coulee continue de brames, notamment de minces brames avec une vitesse de coulee comparativement elevee - Google Patents

Procede et installation de coulee continue de brames, notamment de minces brames avec une vitesse de coulee comparativement elevee Download PDF

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Publication number
WO2001087518A1
WO2001087518A1 PCT/EP2001/005385 EP0105385W WO0187518A1 WO 2001087518 A1 WO2001087518 A1 WO 2001087518A1 EP 0105385 W EP0105385 W EP 0105385W WO 0187518 A1 WO0187518 A1 WO 0187518A1
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WO
WIPO (PCT)
Prior art keywords
rollers
oscillation
mold
strand
driven
Prior art date
Application number
PCT/EP2001/005385
Other languages
German (de)
English (en)
Inventor
Jürgen SUCKER
Original Assignee
Sms Demag Aktiengesellschaft
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 Sms Demag Aktiengesellschaft filed Critical Sms Demag Aktiengesellschaft
Publication of WO2001087518A1 publication Critical patent/WO2001087518A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/12—Accessories for subsequent treating or working cast stock in situ
    • B22D11/128—Accessories for subsequent treating or working cast stock in situ for removing

Definitions

  • the invention relates to a method and a plant for the continuous casting of slabs, in particular thin slabs, with comparatively high casting speeds of, for example, more than 3 m / min, using a mold that can be driven in periodic oscillation, with a roller arranged below it, for guiding and conveying out a Cast strand having strand guide, of which at least some rollers can be driven in pairs or individually in a rotational movement.
  • rollers arranged below the mold are usually driven by electric motors.
  • the driving force of the motors must be large enough to ensure that a given, uniform strand withdrawal speed is taken into account, taking all forces into account.
  • the forces transmitted from the strand to the driven rollers essentially include the dead weight of the strand, the frictional force in the mold, which changes periodically in accordance with the mold oscillation, the frictional forces in the roller bearings, the frictional forces of a grid arranged below the mold - if any - that Forces for bending and bending back the strand from the vertical strand guide into the horizontal strand guide and the forces for overcoming the bulging of the strand shell between the rolls.
  • the accuracy of the alignment of the rollers and the strand shell temperature which varies over the length of the strand, which depends in particular on the casting speed and the intensity of the cooling of the strand in the cooling chamber below the mold, have an influence on the forces mentioned. In thin slab plants with a funnel-shaped pouring area of the mold, additional frictional forces and forces in the mold are used to deform the strand shell taking into account the up and down movement of the mold.
  • the number and arrangement of drivable rollers depends on the system type and system concept. In conventional continuous casting plants with a circular arc shape and a strand thickness of about 150 to 250 mm, it has become established that several pairs of rollers with oppositely driven rollers are distributed over almost the entire arc length and the straightening area at the machine outlet, whereby a uniform distribution of the strand extraction forces over the strand length is achieved ,
  • the drives of the rollers are designed so that a specified strand withdrawal speed can be maintained with the required accuracy and without fluctuations over a range.
  • Continuous casting plants for producing thin strands with a thickness of up to 150 mm, in particular with a thickness between about 30 to 100 mm, are typically designed in such a way that the solidification of the strand takes place in a vertical section which is several meters long and adjoins the mold.
  • the strand is often passed through non-driven rollers and, if necessary, over a partial length through a support grid.
  • the rolls can be set up so that they squeeze the strand with the core still liquid.
  • Mold oscillation is an essential part of the continuous casting process of metals. It ensures the required lubricating effect of the lubricant, for example casting powder or oil, and thus prevents the strand from sticking to the mold walls.
  • lubricant for example casting powder or oil
  • slag has established itself as a lubricant in the mold. It is created by melting casting powder, which is applied to the bathroom mirror in such a way that it permanently covers it.
  • the simplest technical solution which also characterizes the predominant state of the art, is to set a continuous casting mold into an oscillating movement with the aid of a motor-driven eccentric. This results in a sinusoidal oscillation form of the mold, the frequency and amplitude of which is predetermined by the speed of the motor and by the eccentricity of the eccentric.
  • the time component Ts of an oscillation period T, in which the overtaking process V ⁇ oki ⁇ ie> V c takes place during the downward movement of the mold, is generally referred to as a negative strip and is: V c ⁇ - 2 • aresine ()
  • the so-called healing time corresponds to this negative strip during each oscillation period
  • the negative strip, healing time, amplitude and frequency of the mold oscillation as well as their combination tailored to the present operating case are decisive for the quality of the cast product and must be adjusted to the properties of the melt to be cast and the casting powder used.
  • the selection of the oscillation parameters is an essential component in the optimization of the continuous casting process and essentially consists in the selection of an optimal combination of amplitude and frequency.
  • the negative strip should be within certain limits, usually between 15 and 40% of an oscillation period, so that the required values of the healing time in the range between 40 and 200 msec can be achieved.
  • the interrelationships represented by formulas (1) and (2) indicate that, regardless of the oscillation profile of the mold, any combination of the oscillation parameters is not possible if a certain healing time is to be achieved.
  • the object of the invention is to provide a method and a system with which it is possible to achieve comparatively high casting speeds with conventional values of the healing time and the distance between the oscillation marks, without a critical mold acceleration a of about 5 m / sec 2 is exceeded.
  • the invention is particularly advantageous if the superimposed periodic upward and downward movement of the rollers preferably takes place at the frequency of the mold oscillation.
  • the additional up and down movement of the rollers makes the speed of the strand within the Time which corresponds to a period of oscillation of the mold, a time period greater and another time period less than the uniform strand speed. If one adjusts the phase of the additional upward and downward movement of the rollers so that the period with the highest downward speeds of the mold and the period with the lowest strand withdrawal speeds overlap, one obtains a period for the overtaking process (T hea i + delta T), which is greater by the amount (delta T) than the healing time (T hea i) with a uniform casting speed of the strand.
  • the original amplitude of the mold vibrations can be noticeably reduced thanks to the up and down movement of the rollers.
  • This lower amplitude corresponds to a lower mold speed.
  • the acceleration of the mold can be reduced to uncritical values.
  • the method further provides that the superimposed periodic up and down movement of the rollers differs with their speed profile and / or their amplitude from the speed profile or from the amplitude of the periodic up and down movement of the mold at the same frequency.
  • This opens up the possibility of achieving the maximum possible healing time (T hea i) for a predetermined frequency of the mold oscillation and for predetermined limit values of the acceleration of the strand and the mold.
  • a further embodiment of the invention provides that for automatic bath level control in the mold, a signal which is proportional to the speed of the periodic up and down movement of the rollers is used to control the supply of the melt into the mold.
  • a system for carrying out the method according to the invention provides that at least the driven roller of at least one pair of rollers with two opposing rollers, of which at least one roller is driven, are assigned electromechanically or hydraulically controllable drive devices for exciting an oscillation which can be superimposed on the rotary drive movement.
  • rollers are connected to roller holders or roller bearings which are designed for a periodic upward and downward movement in particular.
  • the invention provides that the roller brackets are attached to system parts which are designed for a periodic up and down movement.
  • the invention can also be used in continuous casting plants in which the thickness of the strand is reduced by employing one or more rollers of the roller guide.
  • Fig. 1 the schematic representation of a continuous caster
  • Fig. 2 the speeds and accelerations of the mold
  • Fig. 6 The movement of the strand for three successive mold vibrations for the strand speed shown in Fig. 4.
  • the continuous caster shown in FIG. 1 is used in particular for casting thin slabs, for example 50 mm thick, from steel, with comparatively high casting speeds of 6 m / min or more in some cases, using a mold 1 which can be driven in periodic oscillation by a vibration drive 2 Below the mold 1 there is an initially vertical strand guide 3 with rollers 4 which do not drive the strand 4 in the area of a still liquid core in the strand 4 and at the lower end with rollers 5, 6 for conveying out the cast strand 4, which has already solidified in this area which the roller 5 is motor-driven.
  • a curve guide 9 with a number of rollers 5 ', 5 “, 5'” and 6 'arranged individually and in pairs, which guide the flexible strand 4 divert from the vertical into an arcuate transport direction, after which it is bent by the straightening unit 10 in the straight direction and continued.
  • pairs of rollers for example 5 '", 6', are provided with motor drives.
  • a typical operating case provides a casting speed of 4 m / min.
  • the mold oscillation has a sinusoidal speed profile 10, which results from an oscillation frequency of 260 strokes / min and an amplitude of 3.4 mm.
  • This combination of the oscillation parameters and the casting speed results in a healing time (T ea i) of 56.3 msec and a distance L between the oscillation marks of 15.4 mm.
  • rollers 5, 6 are set in a sinusoidal periodic upward and downward movement (8) with the frequency of the mold oscillation 2 and an amplitude of 1.7 mm, the speed profile of the strand marked 12 is obtained.
  • a major advantage of the invention is therefore to be seen in the fact that the periodic upward and downward movement of the rollers 5, 6 can achieve significantly longer healing times in time with the mold oscillation. As a result, the lubrication of the strand 4 by melted casting powder is noticeably improved, whereby the occurrence of defects on the strand surface is avoided. It should be particularly emphasized that a noticeable increase in the healing time, in this case by 39%, is already achieved by a comparatively small vibration amplitude of the rollers 5, 6.
  • Another application of the invention provides for oscillating rollers 5, 6 to reduce the amplitude of the mold oscillation to such an extent that the original healing time T h ⁇ a ⁇ is maintained.
  • the oscillation of the rollers 5, 6 with an amplitude of 1.7 mm can
  • the mold oscillation can be reduced by 48.2% from 3.4 mm to 1.76 mm without changing the healing time.
  • the speeds 13 and the accelerations 16 of the mold 1 and their maximum values decrease in the same ratio.
  • the maximum acceleration of the mold 1 is reduced from 2.52 m / sec 2 to 1.30 m / sec 2 .
  • Such a reduction in the accelerations opens up the possibility of making the continuous casting installation lighter or using molds with a greater weight, which is advantageous, for example, when using an electromagnetic brake.
  • the mentioned values of the healing time and the distance L between the oscillation marks could only be achieved with mold speeds at which the maximum acceleration of the mold is 7.9 m / sec 2 .
  • Such an acceleration would lead to such high loads on the system parts due to the large mass of a continuous casting mold of approximately 20 t that such a casting operation could not be carried out in practice.
  • the amplitude of the oscillation of the rollers 5, 6 is 1, 8 mm.
  • the maximum acceleration of 5.0 m / sec 2 given to the strand is not critical if, for example, a strand weight of 5 t is assumed, which results from the strand thickness 50 mm, the strand width 1300 mm and the strand length 10,000 mm.
  • FIG. 3 illustrates that the periodic upward and downward movement of the rolls according to the invention opens up the possibility of carrying out the continuous casting at very high casting speeds.
  • FIG. 4 shows that by using non-sinusoidal waveforms of the periodic upward and downward movement of the rollers 5, 6, the advantages already explained with reference to FIG. 3 can be supplemented by increasing the healing time. If the sinusoidal speed profile of the rollers 5, 6 shown in FIG. 3 is replaced by the trapezoidal speed profile shown in FIG. 4, the healing time increases from 28.3 msec to 39.4 msec, ie by 39%.
  • Another advantage of the invention is therefore to be seen in the fact that sufficiently long healing times can be achieved by the periodic upward and downward movement of the rollers 5, 6.
  • a particular advantage of the invention is that the oscillation of the rollers 5, 6 does not lead to an up and down movement of the strand. This is evidenced by the movement profiles of the line shown in FIGS. 5 and 6, which can be attributed to the speed profiles of the line shown in FIGS. 3 and 4. In both cases, the strand executes an uninterrupted downward movement, which slows down and accelerates in time with the oscillation of the mold or roller. If one also takes into account the high oscillation frequency of the mold 1 or the rollers 5, 6, a negative influence of the oscillation of the rollers on the stability of the bath level is excluded.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)

Abstract

L'invention concerne un procédé et une installation de coulée continue de brames, notamment de minces brames en acier, avec des vitesses de coulée comparativement élevées, par exemple, supérieures à 3 m/min, à l'aide d'une lingotière (1) pouvant être entraînée dans une oscillation périodique. Cette installation comprend un guidage de brin (3) qui est placé sous la lingotière (1) et présente des rouleaux (5, 6) permettant de guider et d'extraire une barre (4). Parmi ces rouleaux, au moins quelques uns (5, 6) sont entraînés par paires ou individuellement dans un sens de rotation. Au moins le rouleau entraîné (5) d'au moins une paire de rouleaux est certes entraîné par le mouvement de rotation mais aussi par une oscillation périodique (8) simultanée. A cet effet, des dispositifs d'entraînement à commande électromécanique ou hydraulique sont prévus pour les roues (5, 6).
PCT/EP2001/005385 2000-05-18 2001-05-11 Procede et installation de coulee continue de brames, notamment de minces brames avec une vitesse de coulee comparativement elevee WO2001087518A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE10024508.0 2000-05-18
DE2000124508 DE10024508A1 (de) 2000-05-18 2000-05-18 Verfahren und Anlage zum Stranggießen von Brammen, insbesondere von Dünnbrammen mit vergleichsweise hohen Gießgeschwindigkeiten

Publications (1)

Publication Number Publication Date
WO2001087518A1 true WO2001087518A1 (fr) 2001-11-22

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DE (1) DE10024508A1 (fr)
TW (1) TW495400B (fr)
WO (1) WO2001087518A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007101685A1 (fr) * 2006-03-09 2007-09-13 Sms Demag Ag Dispositif de coulee continue et procede pour faire fonctionner un dispositif de coulee continue
CN113878099A (zh) * 2021-10-12 2022-01-04 山东理工大学 一种抑制回流区温度下行的方法和应用该方法的双辊铸轧系统

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR101949701B1 (ko) * 2017-08-09 2019-02-19 주식회사 포스코 롤러 조립체, 주조 장치 및 이의 롤러 분리 방법

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4294306A (en) * 1979-09-14 1981-10-13 Berenov Alexandr D Withdrawal roll unit for horizontal continuous billet casting machines
US4375830A (en) * 1980-03-20 1983-03-08 Concast Ag Method and apparatus for supporting a steel strand produced during a continuous strand casting method
US4763719A (en) * 1984-02-07 1988-08-16 Voest-Alpine International Corporation Apparatus for discontinuous withdrawing of a cast strand

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4294306A (en) * 1979-09-14 1981-10-13 Berenov Alexandr D Withdrawal roll unit for horizontal continuous billet casting machines
US4375830A (en) * 1980-03-20 1983-03-08 Concast Ag Method and apparatus for supporting a steel strand produced during a continuous strand casting method
US4763719A (en) * 1984-02-07 1988-08-16 Voest-Alpine International Corporation Apparatus for discontinuous withdrawing of a cast strand

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007101685A1 (fr) * 2006-03-09 2007-09-13 Sms Demag Ag Dispositif de coulee continue et procede pour faire fonctionner un dispositif de coulee continue
US8100166B2 (en) 2006-03-09 2012-01-24 Sms Siemag Aktiengesellschaft Continuous casting plant and method of operating a continuous casting plant
CN113878099A (zh) * 2021-10-12 2022-01-04 山东理工大学 一种抑制回流区温度下行的方法和应用该方法的双辊铸轧系统
CN113878099B (zh) * 2021-10-12 2023-06-02 山东理工大学 一种抑制回流区温度下行的方法和应用该方法的双辊铸轧系统

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DE10024508A1 (de) 2001-11-22
TW495400B (en) 2002-07-21

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