CA1143130A - Equipment and process for the electromagnetic stirring of the liquide core in an installation for the continuous casting of steel - Google Patents
Equipment and process for the electromagnetic stirring of the liquide core in an installation for the continuous casting of steelInfo
- Publication number
- CA1143130A CA1143130A CA000340824A CA340824A CA1143130A CA 1143130 A CA1143130 A CA 1143130A CA 000340824 A CA000340824 A CA 000340824A CA 340824 A CA340824 A CA 340824A CA 1143130 A CA1143130 A CA 1143130A
- Authority
- CA
- Canada
- Prior art keywords
- support
- stirring means
- guide
- equipment according
- strand
- 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.)
- Expired
Links
- 238000003756 stirring Methods 0.000 title claims abstract description 94
- 238000009434 installation Methods 0.000 title claims abstract description 9
- 238000009749 continuous casting Methods 0.000 title claims abstract description 7
- 229910000831 Steel Inorganic materials 0.000 title claims abstract description 6
- 239000010959 steel Substances 0.000 title claims abstract description 6
- 238000000034 method Methods 0.000 title description 3
- 230000008569 process Effects 0.000 title description 3
- 239000007788 liquid Substances 0.000 claims abstract description 15
- 229910052729 chemical element Inorganic materials 0.000 claims description 4
- 230000033001 locomotion Effects 0.000 claims description 4
- 238000001816 cooling Methods 0.000 description 8
- 230000008901 benefit Effects 0.000 description 4
- 230000009471 action Effects 0.000 description 3
- 239000000969 carrier Substances 0.000 description 3
- 238000005266 casting Methods 0.000 description 3
- 239000000696 magnetic material Substances 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000005204 segregation Methods 0.000 description 2
- 238000007711 solidification Methods 0.000 description 2
- 230000008023 solidification Effects 0.000 description 2
- 239000007921 spray Substances 0.000 description 2
- 230000006978 adaptation Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000014509 gene expression Effects 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 229920000136 polysorbate Polymers 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
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
- B22D11/122—Accessories for subsequent treating or working cast stock in situ using magnetic fields
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
- Mixers With Rotating Receptacles And Mixers With Vibration Mechanisms (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
In the electromagnetic stirring of the liquid core in a steel strand in a continuous casting installation having a sup-port and guide system divided into segments and having support and guide elements mounted at least three points along their width, stirring means are arranged between a cross-beam and the support and guide elements.
In the electromagnetic stirring of the liquid core in a steel strand in a continuous casting installation having a sup-port and guide system divided into segments and having support and guide elements mounted at least three points along their width, stirring means are arranged between a cross-beam and the support and guide elements.
Description
3C~
The invention relates to equipment for the electromagne-tic stirring of the liquid core in a steel strand in a continuous casting installation, wherein a support guide and at least one stirring means, which sets up -turbulent flow in the liquid core by means of electromagnetic travelling fields, are arranged along the path of movement of the strand; the invention also concerns a process which uses this equipment.
~ or the purpose of improving the internal condition of the cast strand, it is known to impart circulatory movement to the liquid core of the strand with the aid of electromagnetic stirring means and travelling fields. In this way, core segrega-- tion can be reduced and at the same time at least some increase in the globulitic solidification zone can be achieved instead of transcrystalline solidification.
A stirring system is known in which a stirring means is arranged at each side of the strand. The stirring means is arranged between- two large guide rollers and their support members, and extends almost to the surface of the strand. In order to bridge the large support distance between the guide rollers, small support rollers are provided near each side of the stirring means, which ~20 rollers are backed by the support members of the large rollers.
A plurality of these small support rollers are arranged along the width of the strand. The small distance between the stirring means and the surface of the strand calls for less power and therefore smaIler stirring means. The support distance Eor the strand be-tween these small support rollers is, however, always too large - because of the stirring means extending between them, so that harm~
ful bulging of the strand cannot be avoided.
In a further known apparatus for electromagnetically stirring the liquid core, rollers are provided as guide elements along a support and guide track, a stirring means also being pro-vided outside said track~ When large widths of slab are to be 3~30 produced, the guide rollers, made of non-magnetic material, have a large diame-ter and the support distances between them is great;
the use of such rollers can lead to harmful bulging in strands for producing slabs. secause of the rollers arranged between the stirring means and the surface of the strand, a correspondingly large gap is created between the stirring means and the surface of the strand, and this leads to power losses. In order to achieve an effective stirring action in the strand, the stirring means has to be selected to suit size and power. Furthermore, the literature concerned gives no solution to the problem as to how, in the castingof slabs having large differences in width, a stirring action, best suited to the size of product and pro-viding a corresponding improvement in quality~ can be achieved in the strand.
The object of the present invention is to elimi-nate the above-men-tioned disadvantages and to provide a strand-guide frame, having electromagnetic stirring equipment, for a continuous casting installation that is able to produce, in an economical manner, high-quality slabs having large differences in width. Furthermore, the invention is intended to provide procedural measures which enable an optimum stirring action to be achieved in strand, so as to improve its quality.
Accordingly the present invention provides equipment for theelectromagnetic stirring of the liquid core in a steel strand in a continuous casting installation, wherein a support guide and at least one stirring means, which sets up turbulent flow in the liquid core by means of magnetic travelling fields, are arranged along the path of movement of the strand, characterized in that sup~ort columns are arranged between, on the one hand, the support guide elements mounted at least three points along their width, and, on the other hand, a cross-beam carrying the support and guide elements and a-t least a part of ' .
The invention relates to equipment for the electromagne-tic stirring of the liquid core in a steel strand in a continuous casting installation, wherein a support guide and at least one stirring means, which sets up -turbulent flow in the liquid core by means of electromagnetic travelling fields, are arranged along the path of movement of the strand; the invention also concerns a process which uses this equipment.
~ or the purpose of improving the internal condition of the cast strand, it is known to impart circulatory movement to the liquid core of the strand with the aid of electromagnetic stirring means and travelling fields. In this way, core segrega-- tion can be reduced and at the same time at least some increase in the globulitic solidification zone can be achieved instead of transcrystalline solidification.
A stirring system is known in which a stirring means is arranged at each side of the strand. The stirring means is arranged between- two large guide rollers and their support members, and extends almost to the surface of the strand. In order to bridge the large support distance between the guide rollers, small support rollers are provided near each side of the stirring means, which ~20 rollers are backed by the support members of the large rollers.
A plurality of these small support rollers are arranged along the width of the strand. The small distance between the stirring means and the surface of the strand calls for less power and therefore smaIler stirring means. The support distance Eor the strand be-tween these small support rollers is, however, always too large - because of the stirring means extending between them, so that harm~
ful bulging of the strand cannot be avoided.
In a further known apparatus for electromagnetically stirring the liquid core, rollers are provided as guide elements along a support and guide track, a stirring means also being pro-vided outside said track~ When large widths of slab are to be 3~30 produced, the guide rollers, made of non-magnetic material, have a large diame-ter and the support distances between them is great;
the use of such rollers can lead to harmful bulging in strands for producing slabs. secause of the rollers arranged between the stirring means and the surface of the strand, a correspondingly large gap is created between the stirring means and the surface of the strand, and this leads to power losses. In order to achieve an effective stirring action in the strand, the stirring means has to be selected to suit size and power. Furthermore, the literature concerned gives no solution to the problem as to how, in the castingof slabs having large differences in width, a stirring action, best suited to the size of product and pro-viding a corresponding improvement in quality~ can be achieved in the strand.
The object of the present invention is to elimi-nate the above-men-tioned disadvantages and to provide a strand-guide frame, having electromagnetic stirring equipment, for a continuous casting installation that is able to produce, in an economical manner, high-quality slabs having large differences in width. Furthermore, the invention is intended to provide procedural measures which enable an optimum stirring action to be achieved in strand, so as to improve its quality.
Accordingly the present invention provides equipment for theelectromagnetic stirring of the liquid core in a steel strand in a continuous casting installation, wherein a support guide and at least one stirring means, which sets up turbulent flow in the liquid core by means of magnetic travelling fields, are arranged along the path of movement of the strand, characterized in that sup~ort columns are arranged between, on the one hand, the support guide elements mounted at least three points along their width, and, on the other hand, a cross-beam carrying the support and guide elements and a-t least a part of ' .
- 2 -the stirring means is secured outs,ide the s.upport and guide system and between the support and gui.de elements and the cross-beam, as well as between the support columns of the support and guide elements.
The apparatus in accordance with the invention permits the construction of a support and guide frame comprising electromagnetic stirring mean,s for continuous-casting instal-. _ lations, o~ -. .
~3~.31) a very economical basis as regards both capital and operating costs.
The use of a plurality of backing means over the width of the 5Up-port and guide systems enables the thickness of the guide elements, i.e. the diameter of the rollers to be correspondingly reduced.
With the arrangement of the stirring means between the guide ele-ments and the cross-beam, i.e. with the backing for the guide ele-ments, the stirring means can be fitted at a small distance from the surface of the strand. This permits -the use of stirring means which are o~ lower capacity and are therefore smaller, and this, on the one hand, is more economical and, on the other, provides a saving in energy costs. Furthermore, the support and guide system designed in accordance with the invention permits smaller roller spacings, so that harmful bulging and cracks in the crust of the strand as well as break-outs can be prevented, even in the case of large slab widths. A further advantage is that the arran-gement of a plurality of stirring means or stirring elements along the wide side of the support and guide system, makes it possible, with the aid of suitable control- devices, for the travelling fields to be selectively brought into operation, i.e. enables one of the two possible travelling field directions to be selected as required, so that the travelling fields can be selected to suit slabs of differing widths. Thus, optimum turbulent flow in the liquid core of the strand can be set up to provide a correspondingly advanta-geous structure.
Use can be made of support and guide systems in the form of plates or grids, as well as support rollers. Depending upon the position of the stirring means in relation to the bath level, the above-mentioned support and guide means can be used with varying degrees of advantage. In the zone close to the mould, it is pre-ferred to use a supp~rt and guide system in the form of a slidingguide such as a plate or grid.
An advantageous form of the invention is obtained if the
The apparatus in accordance with the invention permits the construction of a support and guide frame comprising electromagnetic stirring mean,s for continuous-casting instal-. _ lations, o~ -. .
~3~.31) a very economical basis as regards both capital and operating costs.
The use of a plurality of backing means over the width of the 5Up-port and guide systems enables the thickness of the guide elements, i.e. the diameter of the rollers to be correspondingly reduced.
With the arrangement of the stirring means between the guide ele-ments and the cross-beam, i.e. with the backing for the guide ele-ments, the stirring means can be fitted at a small distance from the surface of the strand. This permits -the use of stirring means which are o~ lower capacity and are therefore smaller, and this, on the one hand, is more economical and, on the other, provides a saving in energy costs. Furthermore, the support and guide system designed in accordance with the invention permits smaller roller spacings, so that harmful bulging and cracks in the crust of the strand as well as break-outs can be prevented, even in the case of large slab widths. A further advantage is that the arran-gement of a plurality of stirring means or stirring elements along the wide side of the support and guide system, makes it possible, with the aid of suitable control- devices, for the travelling fields to be selectively brought into operation, i.e. enables one of the two possible travelling field directions to be selected as required, so that the travelling fields can be selected to suit slabs of differing widths. Thus, optimum turbulent flow in the liquid core of the strand can be set up to provide a correspondingly advanta-geous structure.
Use can be made of support and guide systems in the form of plates or grids, as well as support rollers. Depending upon the position of the stirring means in relation to the bath level, the above-mentioned support and guide means can be used with varying degrees of advantage. In the zone close to the mould, it is pre-ferred to use a supp~rt and guide system in the form of a slidingguide such as a plate or grid.
An advantageous form of the invention is obtained if the
-3--~3~
support and guide system is divided up into segments or sections and the stirring means can be removed jointly with a s~gment.
Such segments may be removed and fitted with the aid oE known segment-change equipment, Eor example, or they may be lifted out by means of a hoist, so that in the event of trouble the installa-tion is stopped for only short periods.
In the zones where fairly high ferrostatic pressure oc-curs in the liquid core, i~t is expedient for the guide elements to take the form of guide rollers which are mounted atat least three points, the support columns carrying the mountings for the rollers.
If the space and metallurgical conditions associated with the installation permit it, the parts of the stirring means are so arranged that turbulent flow is set up in the strand trans-versely of its longitudinal direction. In a further possible arrangement, the stirring means may be rotatable so as to enable travelling fields to be introduced into the liquid core of the strand in any required direction.
An optimum combination involving number and size of mountings per roller, an advantageous roller diameter and a wide choice of the control variants of the travelling fields as well as the individual travelling-field strengths can be obtained if use is made of rollers which are mounted at four points and if two stirring means are arranged between the support columns for the median portion of the rollers, and a stirring means is arranged between the support columns for each of the two roller end portions.
A separate cross-beam can be provided for each roller divided into several portions. For reasons of cost it is often advantageous for the cross-beam to carry the support columns of several rollers, for example, of one segment.
Apart from the advantages as regards apparatus, the invention also provides considerable advantages affecting the pro-cess when the apparatus is used. It is possible, for example, 3~3~
to set up unidirectional thrust forces with the aid of the stirring means acting on a strand~ This mode of operation results in thorough mixing of the steel and an advantageous equalization of temperature between the liquid core in the zone below the stir-ring means and the zone of the level of the bath.
If permitted by the width of the strand, it may be advantageous if the stirring means set up turbulent flow which, on one side of the centre axis of a broad side of the strand guide means, proceeds in the direction in which the strand is e~tracted, and on the other side of the central axis, in the direction oppo-site to that in which the strand is extracted. In this way it is possible, using a relatively small thrust force, -to produce a closed flow circuit in a rapid manner. This enables the existing travelllng field capacity to be efficiently exploited. An advan-tageous stirring effe~t can be achieved if thrust forces of like magnitude are set up by adjacent stirring means, and the turbulent flow mutually influence each other.
A further advantageous adaptation to suit different casting parameters is achieved if at least one of the adjacently disposed stirring means is caused to set up, in the strand, thrust forces acting on the molten metal, by means of a different elec-trical loading or a different arrangement of the coils, the tur-bulent flows then mutually influencing each other. In addition, the phases can be-diffently loaded in at least one of the stirring means. If, for example, only one stirring means is arranged trans-versely of the longitudinal direction of the strand, it is pre-ferred, in accordance with the invention, to vary the electrical loads of the phases of the stirring means so as to set up diffe-rently acting thrust forces within the travelling field. In these arrangements, an improved metallurgical structure can be achieved, and in particular white bands can be weakened or elimi-- nated, and the negative segregation associated therewith is reduced.
3l3(~
Embodiments will now be described by reference to the drawings, in which:
Fig. 1 illustrates, diagrammatically, part of a conti~
nuous casting installàtion, Fig. 2 is a cross-section through a segment with support rollers and stirring means, Fig. 3 is a cross-section through a segment with a cooling plate and stirring means, Fig. 4 is a cross-section through a segment with support rollers and parts of the stirring means, and Fig. 5 shows a cross-section through a segment with a cooling grid and parts of the stirring means.
Referring to Fig. 1, an open-ended mould of a vertical installation is followed by a strand-guide track consisting of support and guide elements 3 which are secured in replaceable segments 9. The support and guide system may also be of arcuate form. Spray nozzles 4 indicate the secondary cooling equipment.
The segments 9 have support and guide elements in the form of rollers 6, which guide a strand 8 and provide backing against the ferrostatic pressure of the liquid core, which pressure acts on~
the shell of the strand. Arranged outside the rollers 6-is a ~
means 5 for electromagnetically stirring the liquid core 7 in the partially solidified strand. The rollers ~ made of non-magnetic material, preferably stainless steel, are fitted ln the zone of the travelling field between the stirring means 5 and the surface of the strand.
Referring to Fig. 2, the segment 9 of the support and guide system is provided, at one side of the path of the strand, ~with- support and guide elements in the form of rollers 10, divided at several points, and on the other side of the path of the strand, - ~ with continuous rollers 11. The rollers 10, which are mounted~
~ at four points along the width oE the segment 9, are backed by " .
~ -6-' , 3(~
a cross-beam 14 by way oE support and yuide roller bearings 12 and support columns 13, 13'. This cross-beam 14 provides the actual backing for the rollers 10, and between ~hese and the backing 14, as well as between the support frames 13, 13' are ar-ranged four stirring means 15. The stirring means 15 can be con-stituted by a multi-phase connected st:irring means or by only a part of such a means. The segment parts oE the two guide paths are clamped against stops 13 by hydraulic cylinders 17. Such strand-guide segments, provided with at least one pair of rollers, are readily removable from, and replaceable in, the strand guide by means of known segment-changing equipment. Such a segment may however, also comprise a plurality of pairs of rollers, and it can be removed from, and introduced into, the strand-guide track with the aid of a carriage.
The stirrlng means 15 set up turbulent flow in the slab 20 in the longitudinal direction of the strand, and for a large slab 20, all four stirring means 15, and for a smaller slab 20' shown in broken lines, only the two median stirring means 15 are brought into operation. The roller 10, mounted at four points~
permits two stirring means to be arranged between the support columns 13' for the median portion of the roller, and enables a stirring means 15 to be arranged between the support columns 13', 13 of each oE the-two end parts of the roller. The cross-beam 14 can carry the support columns 13, 13' for a plurality of rollers.
The distance between, and the thrust force oE, adjacent stirring means can be so selected that the turbulent flows set up by each stirring means mutually influence each other if the adjacent stirring means have thrust Eorces of like magnitude.
Referring to Fig. 3, the segments 9 with guide elements 22 takes the form of a support and cooling plate. This sliding guide element 22 is mounted at three points over the width of the segment 9, and support columns 23 are provided between the sliding 3~3~
guide 22 and a cross-beam 24. If a slab is to be cast~ then, as shown in this Figure, the two stirring means 25 can set up travel-ling fields effective in different directions. On one side of the central axis 26 of the broad side of the segment 9, for example, turbulent 10w can be set up in the strand 28 in the direction in which said strand is extracted, and on the other side of the axis 26 in the opposite direction. However, the two stirring means 25 are also able to set up unidirectional thrust forces acting in the direction opposite that in which the strand is extracted.
Fig. 4 shows the segment 9 similar to that of Fig. 2.
The support and guide elements are in the form of rollers 30 which are mounted at five points on a cross-beam 32 by means of support columns 31. The four parts of the stirring means that are desi-ganted by the numeral 34 set up turbulent flow transversely of the longitudinal direction of the strand. In this example, the parts 34 of the stirring means may also act as units having at least two phases, or as single phase stirring parts in conjunction with adjacent stirring elements. For the wide slab 20, all four stirring parts are brought into operation, and for the small slab 20', only the two median parts.
Fig. 5 illustrates a further example of a segment 9 having a support and guide element 40 in the form of a cooling grid. The cooling grids are equipped with the usual spray nozzles 41. the cooling grid lS mounted on the cross-beam 44 by means of support columns 43. Stirring parts 45, 45', arranged between the cooling grid 40 and the cross-beam 44 as well as between the supporting columns 43, set up a travelling field transversely of the longitudinal direction of the strand. The direction of the travelling field is indicated by arrows 46, the length of the arrow in each case representing a measure of the differing thrust force within the travelling field. This differing thrust force can be produced by different electrical loading of the phases.
_~_ The median stirring means 45' may consist of a two-phase unit, and the stirring means 45 may each consist of a single phase stirring element, the stirring means 45' and the two stirring ele-ments 45 co-operating to form a single unit in the case of wide slabs.
As a variant, it may also be advantageous if the three parts 45, 45' of the stirring means have at least two phases.
Instead of the differing electrical loading of the phases of the stirring means or parts thereof that are adjacent each other, transversely of the longitudinal direction of the strand, a dif-fering electrical loading can also be provided by stirring means adjacent each other in the longitudinal direction of the strand.
In this arrangement, differing thrust forces, acting on the molten metal, are set up, and~the resultant turbulent flows still mutually influence each other. Instead of the differing electrical loading, a differing form of the coils may be provided. A further possible variant consists in differently loading the phases at least in one of two adjacent stirring means.
- The stirring means 5, 15, 25, 34 and 45, shown in the 2b drawings, can be switched on and off as required by means of suit-able control devices. In addition, one of the two possible tra-velling field directions can be established as required. The magnitude of the thrust force can also be adjusted for each stir-ring means. The various dispositions and control arrangements that have been described permit a large number of individual adap-~ tations to suit the metallurgical requirements or the needs de-- pendent upon product size in contin,uous casting.
It is within the framework of the- teachings of the inven-tion to employ, instead of the support columns 13, 23, 31, 43, also support carriers extending in the direction of travel of the strand over a number of roll bearings. When using the afore-mentioned support carriers the traverses 14, 24, 32, 44, illustrated g_ ..........
3.~3V
by way of example in the embodiments herein disclosed, can be arranged at greater distances from one another and can be struc-tured as transverse carriers or supports. With this a~rangement the accessibility to the electromagnetic stirrers is insured.
Therefore, in the context of the disclosure and claims the expres-sion "support columns" is to be understood as employed in its broader sense as covering the just-mentioned modification and equivalents thereof.
support and guide system is divided up into segments or sections and the stirring means can be removed jointly with a s~gment.
Such segments may be removed and fitted with the aid oE known segment-change equipment, Eor example, or they may be lifted out by means of a hoist, so that in the event of trouble the installa-tion is stopped for only short periods.
In the zones where fairly high ferrostatic pressure oc-curs in the liquid core, i~t is expedient for the guide elements to take the form of guide rollers which are mounted atat least three points, the support columns carrying the mountings for the rollers.
If the space and metallurgical conditions associated with the installation permit it, the parts of the stirring means are so arranged that turbulent flow is set up in the strand trans-versely of its longitudinal direction. In a further possible arrangement, the stirring means may be rotatable so as to enable travelling fields to be introduced into the liquid core of the strand in any required direction.
An optimum combination involving number and size of mountings per roller, an advantageous roller diameter and a wide choice of the control variants of the travelling fields as well as the individual travelling-field strengths can be obtained if use is made of rollers which are mounted at four points and if two stirring means are arranged between the support columns for the median portion of the rollers, and a stirring means is arranged between the support columns for each of the two roller end portions.
A separate cross-beam can be provided for each roller divided into several portions. For reasons of cost it is often advantageous for the cross-beam to carry the support columns of several rollers, for example, of one segment.
Apart from the advantages as regards apparatus, the invention also provides considerable advantages affecting the pro-cess when the apparatus is used. It is possible, for example, 3~3~
to set up unidirectional thrust forces with the aid of the stirring means acting on a strand~ This mode of operation results in thorough mixing of the steel and an advantageous equalization of temperature between the liquid core in the zone below the stir-ring means and the zone of the level of the bath.
If permitted by the width of the strand, it may be advantageous if the stirring means set up turbulent flow which, on one side of the centre axis of a broad side of the strand guide means, proceeds in the direction in which the strand is e~tracted, and on the other side of the central axis, in the direction oppo-site to that in which the strand is extracted. In this way it is possible, using a relatively small thrust force, -to produce a closed flow circuit in a rapid manner. This enables the existing travelllng field capacity to be efficiently exploited. An advan-tageous stirring effe~t can be achieved if thrust forces of like magnitude are set up by adjacent stirring means, and the turbulent flow mutually influence each other.
A further advantageous adaptation to suit different casting parameters is achieved if at least one of the adjacently disposed stirring means is caused to set up, in the strand, thrust forces acting on the molten metal, by means of a different elec-trical loading or a different arrangement of the coils, the tur-bulent flows then mutually influencing each other. In addition, the phases can be-diffently loaded in at least one of the stirring means. If, for example, only one stirring means is arranged trans-versely of the longitudinal direction of the strand, it is pre-ferred, in accordance with the invention, to vary the electrical loads of the phases of the stirring means so as to set up diffe-rently acting thrust forces within the travelling field. In these arrangements, an improved metallurgical structure can be achieved, and in particular white bands can be weakened or elimi-- nated, and the negative segregation associated therewith is reduced.
3l3(~
Embodiments will now be described by reference to the drawings, in which:
Fig. 1 illustrates, diagrammatically, part of a conti~
nuous casting installàtion, Fig. 2 is a cross-section through a segment with support rollers and stirring means, Fig. 3 is a cross-section through a segment with a cooling plate and stirring means, Fig. 4 is a cross-section through a segment with support rollers and parts of the stirring means, and Fig. 5 shows a cross-section through a segment with a cooling grid and parts of the stirring means.
Referring to Fig. 1, an open-ended mould of a vertical installation is followed by a strand-guide track consisting of support and guide elements 3 which are secured in replaceable segments 9. The support and guide system may also be of arcuate form. Spray nozzles 4 indicate the secondary cooling equipment.
The segments 9 have support and guide elements in the form of rollers 6, which guide a strand 8 and provide backing against the ferrostatic pressure of the liquid core, which pressure acts on~
the shell of the strand. Arranged outside the rollers 6-is a ~
means 5 for electromagnetically stirring the liquid core 7 in the partially solidified strand. The rollers ~ made of non-magnetic material, preferably stainless steel, are fitted ln the zone of the travelling field between the stirring means 5 and the surface of the strand.
Referring to Fig. 2, the segment 9 of the support and guide system is provided, at one side of the path of the strand, ~with- support and guide elements in the form of rollers 10, divided at several points, and on the other side of the path of the strand, - ~ with continuous rollers 11. The rollers 10, which are mounted~
~ at four points along the width oE the segment 9, are backed by " .
~ -6-' , 3(~
a cross-beam 14 by way oE support and yuide roller bearings 12 and support columns 13, 13'. This cross-beam 14 provides the actual backing for the rollers 10, and between ~hese and the backing 14, as well as between the support frames 13, 13' are ar-ranged four stirring means 15. The stirring means 15 can be con-stituted by a multi-phase connected st:irring means or by only a part of such a means. The segment parts oE the two guide paths are clamped against stops 13 by hydraulic cylinders 17. Such strand-guide segments, provided with at least one pair of rollers, are readily removable from, and replaceable in, the strand guide by means of known segment-changing equipment. Such a segment may however, also comprise a plurality of pairs of rollers, and it can be removed from, and introduced into, the strand-guide track with the aid of a carriage.
The stirrlng means 15 set up turbulent flow in the slab 20 in the longitudinal direction of the strand, and for a large slab 20, all four stirring means 15, and for a smaller slab 20' shown in broken lines, only the two median stirring means 15 are brought into operation. The roller 10, mounted at four points~
permits two stirring means to be arranged between the support columns 13' for the median portion of the roller, and enables a stirring means 15 to be arranged between the support columns 13', 13 of each oE the-two end parts of the roller. The cross-beam 14 can carry the support columns 13, 13' for a plurality of rollers.
The distance between, and the thrust force oE, adjacent stirring means can be so selected that the turbulent flows set up by each stirring means mutually influence each other if the adjacent stirring means have thrust Eorces of like magnitude.
Referring to Fig. 3, the segments 9 with guide elements 22 takes the form of a support and cooling plate. This sliding guide element 22 is mounted at three points over the width of the segment 9, and support columns 23 are provided between the sliding 3~3~
guide 22 and a cross-beam 24. If a slab is to be cast~ then, as shown in this Figure, the two stirring means 25 can set up travel-ling fields effective in different directions. On one side of the central axis 26 of the broad side of the segment 9, for example, turbulent 10w can be set up in the strand 28 in the direction in which said strand is extracted, and on the other side of the axis 26 in the opposite direction. However, the two stirring means 25 are also able to set up unidirectional thrust forces acting in the direction opposite that in which the strand is extracted.
Fig. 4 shows the segment 9 similar to that of Fig. 2.
The support and guide elements are in the form of rollers 30 which are mounted at five points on a cross-beam 32 by means of support columns 31. The four parts of the stirring means that are desi-ganted by the numeral 34 set up turbulent flow transversely of the longitudinal direction of the strand. In this example, the parts 34 of the stirring means may also act as units having at least two phases, or as single phase stirring parts in conjunction with adjacent stirring elements. For the wide slab 20, all four stirring parts are brought into operation, and for the small slab 20', only the two median parts.
Fig. 5 illustrates a further example of a segment 9 having a support and guide element 40 in the form of a cooling grid. The cooling grids are equipped with the usual spray nozzles 41. the cooling grid lS mounted on the cross-beam 44 by means of support columns 43. Stirring parts 45, 45', arranged between the cooling grid 40 and the cross-beam 44 as well as between the supporting columns 43, set up a travelling field transversely of the longitudinal direction of the strand. The direction of the travelling field is indicated by arrows 46, the length of the arrow in each case representing a measure of the differing thrust force within the travelling field. This differing thrust force can be produced by different electrical loading of the phases.
_~_ The median stirring means 45' may consist of a two-phase unit, and the stirring means 45 may each consist of a single phase stirring element, the stirring means 45' and the two stirring ele-ments 45 co-operating to form a single unit in the case of wide slabs.
As a variant, it may also be advantageous if the three parts 45, 45' of the stirring means have at least two phases.
Instead of the differing electrical loading of the phases of the stirring means or parts thereof that are adjacent each other, transversely of the longitudinal direction of the strand, a dif-fering electrical loading can also be provided by stirring means adjacent each other in the longitudinal direction of the strand.
In this arrangement, differing thrust forces, acting on the molten metal, are set up, and~the resultant turbulent flows still mutually influence each other. Instead of the differing electrical loading, a differing form of the coils may be provided. A further possible variant consists in differently loading the phases at least in one of two adjacent stirring means.
- The stirring means 5, 15, 25, 34 and 45, shown in the 2b drawings, can be switched on and off as required by means of suit-able control devices. In addition, one of the two possible tra-velling field directions can be established as required. The magnitude of the thrust force can also be adjusted for each stir-ring means. The various dispositions and control arrangements that have been described permit a large number of individual adap-~ tations to suit the metallurgical requirements or the needs de-- pendent upon product size in contin,uous casting.
It is within the framework of the- teachings of the inven-tion to employ, instead of the support columns 13, 23, 31, 43, also support carriers extending in the direction of travel of the strand over a number of roll bearings. When using the afore-mentioned support carriers the traverses 14, 24, 32, 44, illustrated g_ ..........
3.~3V
by way of example in the embodiments herein disclosed, can be arranged at greater distances from one another and can be struc-tured as transverse carriers or supports. With this a~rangement the accessibility to the electromagnetic stirrers is insured.
Therefore, in the context of the disclosure and claims the expres-sion "support columns" is to be understood as employed in its broader sense as covering the just-mentioned modification and equivalents thereof.
Claims (14)
1. Equipment for the electromagnetic stirring of the liquid core in a steel strand in a continuous casting instal-lation, wherein a support guide and at least one stirring means, which sets up turbulent flow in the liquid core by means of magnetic travelling fields, are arranged along the path of move-ment of the strand, characterized in that support columns are arranged between, on the one hand, the support guide elements mounted at least three points along their width, and, on the other hand, a cross-beam carrying the support and guide elements and at least a part of the stirring means is secured outside the support and guide system and between the support and guide ele-ments and the cross-beam, as well as between the support columns of the support and guide elements.
2. Equipment according to Claim 1, characterized in that the support and guide system is divided up into segments, and the stirring means can be removed jointly with a support and guide segment.
3. Equipment according to claim 1, characterized in that the part of the stirring means are designed to set up turbulent flow transversely of the longitudinal direction of the strand.
4. Equipment according to claim 1, characterized in that at least one stirring means, setting up turbulent flow in the longitudinal direction of the strand, is provided between the support columns.
5. Equipment according to claim 2, characterized in that the part of the stirring means are designed to set up turbulent flow transversely of the longitudinal direction of the strand.
6. Equipment according to claim 2, characterized in that at least one stirring means, setting up turbulent flow in the longitudinal direction of the strand, is provided between the support columns.
7. Equipment according to any one of claims 1, 2 and 3, characterized in that the support and guide elements consist of guide rollers mounted at three points, and the support columns carry the roller mountings.
8. Equipment according to any one of claims 4, 5 and 6, characterized in that the support and guide elements consist of guide rollers mounted at three points, and the support columns carry the roller mountings.
9. Equipment according to any one of claims 1, 2 and 3, characterized in that the support and guide elements take the form of sliding guides.
10. Equipment according to any one of claims 4, 5 and 6, characterized in that the support and guide elements take the form of sliding guides.
11. Equipment according to any one of claims 1, 2 and 3, characterized in that the guide elements consist of rollers mounted at four points, and two stirring means are ar-ranged between the support columns for the median portion of the rollers and a stirring means is arranged between the support columns for each of the two end portions of the roller.
12. Equipment according to any one of claims 4, 5 and 6, characterized in that the guide elements consist of rollers mounted at four points, and two stirring means are arranged between the support columns. for the median portion of the rollers and a stirring means is a arranged between the support columns for each of the two end portions of the roller.
13. Equipment according to any one of claims 1, 2 and 3, characterized in that the cross-beam carries the support columns for all the rollers of a segment.
14, Equipment according to any one of claims 1, 2 and 3, characterized in that a phase coil of a part of the stirring means is arranged opposite a phase coil of an adjacent part of the stirring means for setting up an unequal thrust force.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CH12289/78-4 | 1978-12-01 | ||
| CH1228978A CH633464A5 (en) | 1978-12-01 | 1978-12-01 | CONTINUOUS RAILWAY WITH ELECTROMAGNETIC STIRRING DEVICE IN A STEEL CONTINUOUS CASTING SYSTEM. |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1143130A true CA1143130A (en) | 1983-03-22 |
Family
ID=4381628
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000340824A Expired CA1143130A (en) | 1978-12-01 | 1979-11-28 | Equipment and process for the electromagnetic stirring of the liquide core in an installation for the continuous casting of steel |
Country Status (9)
| Country | Link |
|---|---|
| EP (1) | EP0011861A1 (en) |
| JP (1) | JPS5577963A (en) |
| AU (1) | AU524877B2 (en) |
| CA (1) | CA1143130A (en) |
| CH (1) | CH633464A5 (en) |
| DE (1) | DE2947869A1 (en) |
| ES (1) | ES486843A1 (en) |
| SE (1) | SE431171B (en) |
| ZA (1) | ZA796525B (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS58215254A (en) * | 1982-06-08 | 1983-12-14 | Kawasaki Steel Corp | Electromagnetic stirrer disposed right under casting mold of continuous casting machine or in posterior position |
| AT519029B1 (en) * | 2016-08-31 | 2019-10-15 | Primetals Technologies Austria GmbH | Stirring coil arrangement in a continuous casting plant |
| CN116352039B (en) * | 2023-06-01 | 2023-08-22 | 江苏省沙钢钢铁研究院有限公司 | Center quality control method of continuous casting billet for bridge steel |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1962341B2 (en) * | 1969-12-12 | 1971-06-24 | Aeg Elotherm Gmbh | ARRANGEMENT OF A MULTI-PHASE ELECTROMAGNETIC WINDING ON THE STRAND GUIDE FRAMEWORK OF A CONTINUOUS CASTING PLANT |
| JPS5252895Y2 (en) * | 1973-04-18 | 1977-12-01 | ||
| JPS5348171B2 (en) * | 1974-06-24 | 1978-12-27 | ||
| SE410153B (en) * | 1976-05-21 | 1979-10-01 | Asea Ab | STRAND MOLDING FACILITY |
| DE2743505C3 (en) * | 1977-09-23 | 1984-09-20 | Aeg-Elotherm Gmbh, 5630 Remscheid | Device for generating an electromagnetic traveling field within the support roller conveyor of a slab caster |
-
1978
- 1978-12-01 CH CH1228978A patent/CH633464A5/en not_active IP Right Cessation
-
1979
- 1979-11-28 DE DE19792947869 patent/DE2947869A1/en not_active Withdrawn
- 1979-11-28 CA CA000340824A patent/CA1143130A/en not_active Expired
- 1979-11-28 AU AU53258/79A patent/AU524877B2/en not_active Expired - Fee Related
- 1979-11-29 EP EP79104751A patent/EP0011861A1/en not_active Ceased
- 1979-11-30 SE SE7909880A patent/SE431171B/en not_active Application Discontinuation
- 1979-11-30 ZA ZA00796525A patent/ZA796525B/en unknown
- 1979-11-30 ES ES486843A patent/ES486843A1/en not_active Expired
- 1979-12-01 JP JP15500479A patent/JPS5577963A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| SE7909880L (en) | 1980-06-02 |
| SE431171B (en) | 1984-01-23 |
| JPS5577963A (en) | 1980-06-12 |
| AU524877B2 (en) | 1982-10-07 |
| CH633464A5 (en) | 1982-12-15 |
| AU5325879A (en) | 1980-06-05 |
| ZA796525B (en) | 1980-11-26 |
| EP0011861A1 (en) | 1980-06-11 |
| ES486843A1 (en) | 1980-05-16 |
| DE2947869A1 (en) | 1980-06-04 |
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| MKEX | Expiry |