US3752210A - Method for controlling forces on a strand as it solidifies - Google Patents

Method for controlling forces on a strand as it solidifies Download PDF

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Publication number
US3752210A
US3752210A US00174350A US3752210DA US3752210A US 3752210 A US3752210 A US 3752210A US 00174350 A US00174350 A US 00174350A US 3752210D A US3752210D A US 3752210DA US 3752210 A US3752210 A US 3752210A
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strand
speed
force
rolls
forces
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US00174350A
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English (en)
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F Gallucci
F Slamar
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United States Steel Corp
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Steel Corp
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    • 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
    • B22D11/16—Controlling or regulating processes or operations
    • B22D11/20—Controlling or regulating processes or operations for removing cast stock

Definitions

  • ABSTRACT A method and mechanism for controlling the forces on a partially solidified strand formed in a continuouscasting operation. A speed-regulating tractive force is applied to the strand at a location in the line preceding that where the starter bar is disconnected. 1n apparatus utilizing a relatively long flexible starter bar, auxiliary tractive forces are applied at preceding locations.
  • the auxiliary tractive forces may be applied at locations following the speed-regulating force.
  • the speed-regulating force is maintained at a predetermined maximum, and the auxiliary forces adjusted accordingly to supply the increasing force needed tomove the strand, yet avoid excessive tensile or compressive stresses.
  • liquid metal is poured continuously into a vertically oscillating, water cooled, open-ended mold, which may be either straight or curved.
  • a partially solidified strand of indefinite length emerges from the bottom of the mold and travels between series of rolls which engage opposite faces thereof.
  • these rolls may include a straight vertical guide-roll rack immediately beneath the mold, power driven pinch rolls and/or bending rolls beneath the guide-rollrack, a curved roll-rack which changes the directionof travel of the strand from vertical to horizontal, a straightener, optionally in-Iine work-roll stands, andfinally a run-out table on which the strand is severed to appropriate lengths for further processing.
  • Similar parts may be used with curved molds, except that there are no straight guide-roll-rack nor bending rolls, since the strand is cast with a curvature.
  • the strand As the strand leaves the mold, only a thin outside skin has solidified, and the core remains liquid.
  • the strand is subjected to intense water sprays as it passes the various rolls, referred to as secondary cooling, whereby it solidifies throughout its cross section by the time it.
  • An object-of our invention is to provide a continuouscasting operation and apparatus in which we employ an improved method and mechanism for controlling lengthwise forces on the solidifying strand, thereby avoiding defects in the ultimate product.
  • a further object is to provide an improved forcecontrolling method and mechanism in which we apply a speed-regulating tractive force to the strand at a location preceding that where the starter bar is disconnected (e.g., at the straightener), maintain the speedregulating force at a predetermined maximum, and apply controlled auxiliary tractive forces at other locations to minimize or eliminate stresses in the strand.
  • a further object, applicable to apparatus utilizing a relatively long flexible starter bar, is to provide a force controlling method and mechanism in which we subject the strand to a speed-regulating drive at an advanced location in the line, and to a series of adjustable auxiliary tractive forces along its length between the mold and the speed-regulating drive, whereby we maintain lengthwise forces in the strand at any desired value or eliminate tension altogether in favor of a compression stress.
  • FIG. 1 is a partly diagrammatic vertical section of a continuous-casting apparatus which utilizes a relatively long flexible starter bar and is equipped with one embodiment of our force-controlling mechanism, the
  • FIG. 2 is a graph showing a typical relation of the forces on a strand in an apparatus such as that shown in FIG. 1;
  • FIG. 3 is a block diagram of an electric circuit suitable for use in the embodiment of our mechanism shown in -FIG. l;
  • FIG.4 is a block diagram of a similar circuit, but embodying computer control for automatic operationjand
  • FIG. 5 is a partly diagrammatic vertical section of a continuous-casting apparatus which utilizes a rigid starter :bar and is equipped with a modified embodiment of our force-controlling mechanism, the parts :being shown in the position they occupy after the casting operation is underway and the starter bar disconnected.
  • the continuous-casting apparatus illustrated in FIG. 1 includes from top to bottom a straight mold 10, a
  • Liquid metal is introduced to the mold .from a tundish 17 supported thereabove.
  • a starter bar 18 is inserted in the lower end of the mold and extends through and beyond the straightener 15.
  • a partially solidified strand .8 emerges from the lower end of the mold and descends following the starter bar between the various sets of rolls. After the leading end of th strand S clears the straightener 15, the starter bar is disconnected and stored in readiness to start the next cast.
  • the apparatus illustrated in FIG. I utilizes a relatively long flexible starter bar, which is not disconnected until it reaches the run- .out table, but our invention in modified form can be used with apparatus which utilizes a starter bar (rigid .or flexible) disconnected above the bending rolls, as shown in FIG. 5 and hereinafter described. Also it can be used with apparatus which has a curved mold, or which has a varying radius of curvature in the curved roll-rack, or which has in-line work rolls, etc., all of which are well known in the continuous-casting art.
  • the apparatus has sets of driven rolls 20 and 20a which engage opposite faces of first the starter bar 18 and later the strand S at an advanced location in the line and which we refer to as our speed-regulating drive.”
  • This embodiment has a first set of auxiliary driven rolls 21, which engage opposite faces of the strand near the bottom of the mold and which we refer to as our No. 1 drive.
  • the apparatus has longitudinally spaced sets of auxiliary driven rolls 22 and 23, which we refer to as our "No. 2 drive and No. 3 drive" respectively. All the other rolls shown can be idlers.
  • the rolls 20 and 20a of our speed-regulating drive are lo cated fore and aft of the straightener 15; our No. 1 drive 21 is located between the guide-roll rack 12 and the bending roll 13; our No. 2 and 3 drives 22 and 23 are located intermediate the length of the curved rollrack 14. Nevertheless it is apparent that the exact location and number of these drives can vary.
  • our speed-regulating drive 20, 20a acts as a brake to restrain the starter bar from descending under its own weight.
  • our auxiliary drives With their current set points at zero, whereby they act as idlers.
  • the leading end of the strand S passes through the guide roll-rack 12, our No. 1 drive 21 (operating as an idler at this time), and into the bending roll unit 13.
  • the speed-regulating drive 20, 20a furnishes this force. The farther the strand progresses, the greater the resistance to its movement and the greater the tractive force or torque needed to propel it at a given speed.
  • the motors for the various drives can be constant-field d-c motors, which have a characteristic that at any speed their torque output is directly proportional to the current valve.
  • a predetermined maximum for example amperes
  • the current to the speedregulating drive 20, 20a may remain at the exemplary maximum of 10 amperes, and the current to the No. l, 2 and 3 drives 21, 22 and 23 may be at 20, and 10 amperes respectively.
  • FIG. 2 is a graph illustrating a typical force profile on the strand when our method is practiced with the casting apparatus shown in FIG. 1.
  • the abscissae represent distances from the bottom of mold 10.
  • Positive ordinates represent tensil forces on the strand and negative ordinates compressive forces.
  • Curve A represents the line resistance to movement of the strand through the casting apparatus.
  • Curve B represents the force tending to move the strand through the apparatus under its own weight.
  • Curve C represents the difference between Curves A and B, or the tractive force which must be supplied to move' the strand.
  • Curve C also represents the magnitude of tensil stresses in the strand at various points along its length if the speed-regulating drive alone were used to pull the strand through the apparatus.
  • Curve D shows an example of the magnitude of tensil stresses in the strand when our method is followed. From the mold 10 to our No. 1 drive, Curve D is the same as Curve C. At No. 1 drive we apply a tractive force to the strand and thereby place it in compression. Following No. 1 drive Curve D rises parallel with Curve C until it reaches No. 2 drive, where we again apply a tractive force which restores the compression. The same relation takes place between No. 2 drive and No. 3 drive, and again between No. 3 drive and the speed-regulating drive. In this manner the strand remains under slight compression substantially throughout the operation.
  • FIG. 3 illustrates in block diagram a typical electric circuit we can use for manually controlling the various drive motors.
  • Constant-field d-c motors for the two sets of rolls 20 and 20a of the speed-regulating drive are indicated at 26 and 26a respectively.
  • We energize these motors through a closed-loop speed-regulating circuit 28, which includes a power supply 29, an amplifier 30 and a tachometer 31.
  • the two motors 26 and 26a run at essentially a constant speed, which we change only to change the strand speed.
  • An ammeter 33 indicates the magnitude of current the motors draw to maintain this speed, which magnitude is a measure of the torque output of the motors.
  • Our-No. 2 snd 3 drives 22 and 23 have closed-loop current-regulating circuits 44 and 45 which are similar to circuit 37 of No. 1 drive. After the leading end of the strand reaches No. 2 drive, we maintain the current to both motors. 26 and 26a of the speed-regulating drive and to motor 36 of our No. 1 drive at constant magnitudes and increase-the current to No. 2 drive to supply the increasing tractive force needed to move the strand. After the leading end reaches No. 3 drive, we use this drive in the same fashion, keeping the current to No. 2 drive constant.
  • FIG. 4 illustrates in block diagram the way in which we can make the foregoing adjustments automatically.
  • a pulse generator 46 to motor 26:; of our speed-regulating drive to track the leading end of the strand.
  • a digital computer 47 which we in turn connect to the control circuits 37, 44 and 45 for No. 1, 2 and 3 drives. In this manner the computer automatically adjusts the current to each drive to achieve the same effect as in the manual control already described.
  • FIG. 5 illustrates a continuous-casting apparatus in which the starter bar 50 is rigid and to which we may apply our invention in modified form.
  • the apparatus includes from top to bottom a straight mold 51, a straight vertical guide-roll-rack 52, power-driven pinch rolls 53, a curved roll-rack 54, a straightener 55, and a horizontal roll-rack 56.
  • the curved roll-rack has at least one switch section 57 in which some of the rolls are journaled.
  • the switch section can open to allow the starter bar 50 to decend vertically after it is disconnected from the leading end of the strand, as shown for example in Foldessy US. Pat. No. 3,338,297.
  • the pinch rolls 53 become the speed-regulating drive.
  • the pinch rolls 53 engage the starter bar and act as a brake to restrain it from descending under its own weight.
  • the starter bar is disconnected and the switch section 57 closed, the strand S enters the curved roll-rack 54 and requires an increasing tractive force to propel it.
  • auxiliary pairs of driven rolls 58, 59 and 60 which we again refer to as our No. l, 2 and 3 drives.
  • the rolls in the straightener 55 are driven, but all the other rolls can be idlers.
  • our invention assures that a solidifying continuously-cast strand is relieved of any excessive longitudinal stresses as it solidifies.
  • a small compressive stress during most of the operation, as Curve D of FIG. 2 indicates.
  • the speed-regulating drive pulls the strand, and our auxiliary drives act to relieve excessive compressive stresses which tend to bulge the strand, as well as excessive tensile stresses.
  • our invention avoids defects in the strand caused by lengthwise stresses, and permits a higher casting speed for crack-sensitive steel grades.
  • a starter bar is connected to the leading end of said strand as the leading end emerges from the mold, but is disconnected therefrom at a location spaced below the mold;

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Forwarding And Storing Of Filamentary Material (AREA)
US00174350A 1971-08-24 1971-08-24 Method for controlling forces on a strand as it solidifies Expired - Lifetime US3752210A (en)

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JP (1) JPS556471B2 (enrdf_load_html_response)
AR (1) AR194006A1 (enrdf_load_html_response)
AT (1) AT329207B (enrdf_load_html_response)
BE (1) BE787812A (enrdf_load_html_response)
BR (1) BR7205766D0 (enrdf_load_html_response)
CA (1) CA957125A (enrdf_load_html_response)
DE (1) DE2241032B2 (enrdf_load_html_response)
ES (1) ES406048A1 (enrdf_load_html_response)
FR (1) FR2150420B1 (enrdf_load_html_response)
GB (1) GB1411638A (enrdf_load_html_response)
IT (1) IT964992B (enrdf_load_html_response)
NL (1) NL172922C (enrdf_load_html_response)
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Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3893503A (en) * 1973-07-24 1975-07-08 Voest Ag Continuous casting plant
US4090549A (en) * 1974-07-12 1978-05-23 United States Steel Corporation Method and mechanism for determining forces on a solidifying casting
US4148349A (en) * 1976-05-08 1979-04-10 Yutaka Sumita Method for controlling slippage between rolls and a slab in a continuous compression casting apparatus
US4476915A (en) * 1980-03-22 1984-10-16 Werner Rahmfeld Method for regulating individual drives of an arcuately shaped multi-roller continuous strand casting machine for metal, particularly steel
EP0357393A3 (en) * 1988-08-31 1991-08-14 Gladwin Corporation Continuous caster roll monitor
US5201813A (en) * 1991-03-20 1993-04-13 Westinghouse Electric Corp. Roll monitor sled data handling system
CN114150386A (zh) * 2021-11-22 2022-03-08 江苏九九久新材料有限公司 冻胶丝落丝方法

Families Citing this family (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5551664B2 (enrdf_load_html_response) * 1973-12-31 1980-12-25
JPS5410925B2 (enrdf_load_html_response) * 1973-12-31 1979-05-10
JPS619105B2 (enrdf_load_html_response) * 1974-04-02 1986-03-19 Nippon Steel Corp
JPS52123932A (en) * 1976-04-10 1977-10-18 Nippon Steel Corp Continuous casting method
JPS561254A (en) * 1979-06-19 1981-01-08 Nichidoku Jukogyo Kk Control unit for progressing and guiding continuous body in curved track in particular in continuous casting equipment
JPS5842388U (ja) * 1981-09-14 1983-03-22 三菱重工業株式会社 回転式圧縮機
AT378707B (de) * 1983-01-11 1985-09-25 Voest Alpine Ag Verfahren zum ueberwachen einer bogenstranggiessanlage
DE19829605C1 (de) * 1998-07-02 1999-10-14 Schloemann Siemag Ag Strangabzugsverfahren
CN114905017B (zh) * 2022-06-16 2024-02-02 中国重型机械研究院股份公司 一种自适应控制铸轧速度的连铸大压下装置和方法

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3542118A (en) * 1967-12-20 1970-11-24 Concast Inc Dummy bar handling mechanism
US3550674A (en) * 1968-01-19 1970-12-29 United States Steel Corp Guide-roll arrangement for continuous casting
US3557865A (en) * 1968-03-18 1971-01-26 United States Steel Corp Mechanism for measuring loads on pinch rolls of continuous-casting machine
US3566951A (en) * 1967-02-24 1971-03-02 Mannesmann Ag Method of equalizing stresses in the conveyance and guidance of continuous castings

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3614978A (en) * 1968-07-01 1971-10-26 Westinghouse Electric Corp Computerized continuous casting system control responsive to strand position

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3566951A (en) * 1967-02-24 1971-03-02 Mannesmann Ag Method of equalizing stresses in the conveyance and guidance of continuous castings
US3542118A (en) * 1967-12-20 1970-11-24 Concast Inc Dummy bar handling mechanism
US3550674A (en) * 1968-01-19 1970-12-29 United States Steel Corp Guide-roll arrangement for continuous casting
US3557865A (en) * 1968-03-18 1971-01-26 United States Steel Corp Mechanism for measuring loads on pinch rolls of continuous-casting machine

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3893503A (en) * 1973-07-24 1975-07-08 Voest Ag Continuous casting plant
US4090549A (en) * 1974-07-12 1978-05-23 United States Steel Corporation Method and mechanism for determining forces on a solidifying casting
US4148349A (en) * 1976-05-08 1979-04-10 Yutaka Sumita Method for controlling slippage between rolls and a slab in a continuous compression casting apparatus
US4476915A (en) * 1980-03-22 1984-10-16 Werner Rahmfeld Method for regulating individual drives of an arcuately shaped multi-roller continuous strand casting machine for metal, particularly steel
EP0357393A3 (en) * 1988-08-31 1991-08-14 Gladwin Corporation Continuous caster roll monitor
US5201813A (en) * 1991-03-20 1993-04-13 Westinghouse Electric Corp. Roll monitor sled data handling system
CN114150386A (zh) * 2021-11-22 2022-03-08 江苏九九久新材料有限公司 冻胶丝落丝方法

Also Published As

Publication number Publication date
DE2241032A1 (de) 1973-03-01
YU215772A (en) 1982-02-28
BR7205766D0 (pt) 1973-08-23
ES406048A1 (es) 1976-11-16
IT964992B (it) 1974-01-31
CA957125A (en) 1974-11-05
JPS4828725A (enrdf_load_html_response) 1973-04-16
NL172922C (nl) 1983-11-16
NL7211569A (enrdf_load_html_response) 1973-02-27
FR2150420A1 (enrdf_load_html_response) 1973-04-06
ZA725600B (en) 1973-11-28
FR2150420B1 (enrdf_load_html_response) 1977-12-30
AU4563072A (en) 1974-02-21
AT329207B (de) 1976-04-26
ATA728272A (de) 1975-07-15
GB1411638A (en) 1975-10-29
AR194006A1 (es) 1973-06-12
BE787812A (fr) 1973-02-21
JPS556471B2 (enrdf_load_html_response) 1980-02-16
RO60663A (enrdf_load_html_response) 1977-02-15
NL172922B (nl) 1983-06-16
DE2241032B2 (de) 1979-11-29

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Owner name: USX CORPORATION, A CORP. OF DE, STATELESS

Free format text: MERGER;ASSIGNOR:UNITED STATES STEEL CORPORATION (MERGED INTO);REEL/FRAME:005060/0960

Effective date: 19880112