CA1204574A

CA1204574A - Apparatus for continuous casting of steel

Info

Publication number: CA1204574A
Application number: CA000409596A
Authority: CA
Inventors: Hanji Oba; Nobuyoshi Tanaka; Akihiro Saoka; Akira Ishikawa
Original assignee: Nippon Steel Corp
Current assignee: Nippon Steel Corp
Priority date: 1981-08-18
Filing date: 1982-08-17
Publication date: 1986-05-20
Also published as: GB2105229A; GB2105229B; DE3230573A1; DE3230573C2

Abstract

APPARATUS FOR CONTINUOUS CASTING OF STEEL

ABSTRACT OF THE DISCLOSURE

In the continuous casting of steel, beam blanks and reatangular strands are produced by a continuous casting machine specifically designed for the production of a beam blank or a rectangular strand, e.g., a slab.
It is an object of the present invention to provide an apparatus for the continuous casting of steel in which the cost of construction is not high and in which different kinds of strands, i.e., a beam blank and a rectangular strand, can be optionally produced in accordance with demand.
The CCM of the present invention is characterized in that at least one of the supporting-roll assemblies is used for supporting different kinds of strands. Preferably, the supporting roll assemblies provided directly below the mold are interchangeable when the production of a beam blank is changed to the production of a slab. In the supporting-roll assemblies for supporting different kinds of strands, at least one of the supporting rolls, preferably only the supporting roll at the L side, is displacable.

Description

~(3~i7~

_PPARATUS FOR CONTINUOUS CASTING OF STEEL

The presen-t invention relates to an apparatus for the coutinuous casting of steel and provides an apparatus for the continuous casting of steel, which apparatus can option-ally produce different kinds of strands, e.y., a beam blank and a rectangular strand, such as a slab, a bloom, and a billet, by means of a single apparatus.
Conventionally, sections, such as H-steels and I-steels, have been produced by rough-rolling ingots so as to form beam blanks and subsequently rough- and finishing-rolling 10 the team blanks. Recently, sections have been produced by forming beam blanks by the continuous-casting method and subsequen-tly rough- and finishing-rolling the beam blanks so s as to form sections.
Since the demand for sec-tions, and thus the amount of 15 sections produced per month or year in steel mills, greatly varies and since the cost of constructing a continuous--casting apparatus is enormous, a continuous-casting apparatus is economical only in that it can mass produce strands. Therefore, the installation of a continuous-20 -casting apparatus for the production of beam blanks has enccnomical limitations. Contrary to this, continuous casting apparatuses have been constructed in a number of countries in order to produce slabs from which hot-rolled strips are produced. These continuous casting apparatuses 25 for the produc-tion of slabs are becoming more popular because their productivity is high and, further, their slab-production yield is higher than -that when the rouyh--rolling method of producing ingots is employed. In other words, conventional continuous-casting apparatuses were designed to specifically produce either beam blanks or slabs. The circumstances under which beam blanks can be mass produced by means oE a continuous casting apparatus are very limited while there is no such limitation in the mass production of slabs in a continuous casting apparatus.
The present inventors therefore considered that if a beam blank and a rectangular strand, such as slab, could be optionally produced in a single continuous-casting apparatus, the process would be economical and the production Or various strands in accordance with demand could be realized. The present inventors therefore developed the continuous-casting apparatus of the present invention.
The beam blank herein indicates a strand which is used as the starting steel section in the production of H-steels, I-steels, and the like. The rectangular strand herein indicates a slab, a bloom, a billet, or the like. team blanks and rectangular strands are collectively and simply referred to herein as strands.
The continuous casting of a beam blank is carried out under considerably difficult technically conditions, and, therefore, only a beam blank having a small cross section is produced. On the other hand, the continuous casting of a rectangular strand, especially a large slab, is not carried ou-t under technically difficult conditions and therefore the productivity is high in accordance with the large cross 5'7~

sec-tion of the rectangular strand. Consequently, optionally producing differen-t kinds of strands, i.e., a bearn blank and a rec-tangular s-trand, by means of a single continuous-casting apparatus has not prevlously been conceived in the art of continuous casting.
i It is an object of the present invention to provide an apparatus for the continuous casting of steel in which the it cost of construction is not high and in which different kinds of strands, i.e., a beam blank and a rectangular strand, can be op-tionally produced in accordance with demand.
It is another object of the present invention to provide an apparatus ror the continuous casting of steel in which beam blanks and rectangular strands can be in-terchangeably and economically produced irregardless of the proportion of beam blanks to rectangular strands.
In accordance with the objects of the present invention, there is provided a continuous-casting apparatus comprising a mold and a plurality of supporting-roll assemblies which are arranged subsequent to said mold, characterized in that: at leas-t one supporting-roll assembly is a combined--use assembly capable of supporting a rec-tangular strand in addition to a beam blank; if the apparatus includes a non--combined-use supporting-roll assembly, the supporting-roll assembly for a beam blank can be replaced by a supporting--roll assembly for a rectangular strand; and the mold used specifically for a team klank can be replaced by a mold used specifically for a rectangular strand, thereby allowing the production of a rectangular strand in addition to a beam blank by means of a sigle continuous-casting apparatus.
In an apparatus for the continuous cas-ting of steel, (hereinafter referred to as the CCM) the changing of differ-ent kinds of strands must be easily and quickly carried out so that a beam blank and either a slab, a bloom, or a billet can be op-tionally and consecutively produced. speedy and easy changing of the different kinds of strand can be the most effectively carried out by simply replacing the mold.
Therefore, all the supporting-roll assemblies of the CCM, e.g., apron rolls, guide rolls, pinch rolls, and bending rolls, should be capable of supporting a beam blank, a slab, a billet, and a bloom. The CCM is hereinafter referred to as a total combined-use supporting-roll CCM.
The present invention also provides a CCM (hereinaf-ter referred to as an exclusive-use supportiny-roll CCM) in which: à ~supporting-roll assembly provided directly below the mold supports exclusively either a beam blank or a rectangular strand; the supporting-roll assembly for support-ing a beam blank can be replaced by the supporting-roll assembly or supporting a rectangular strand and vice versa;
and, supporting-roll assemblies which are arranged subsequent to the supporting-roll assembly directly below the mold are combined-use assemblies which are capable of supporting a rectangular strand in addition to a beam blank. In the exclusive-use supporting-roll CCM, the time necessary for re-pair of the parts of said CCM if break-out occurs is shor-ter than in the total combined-use supporting-roll assemblyO In addition, since replacement of the supporting-roll assembly ~26:~5~

directly below the mold, adjustment of the distance between the rolls of the assembly generally beiny difficult, can be promptly effected in the exclusive-use supporting-roll CCM, the preparation period before casting is lessened as compared with that in the total combined-use supporting roll CCM.
In the exclusive-use supporting-roll CCM, it is prefer-red tha-t the mold and the supporting-roll assembly provided directly below the mold, for supporting a beam blank be mounted on a common framework and, further, that the mold and the supporting-roll assembly provided directly below the mold, for supporting a rectangular strand be mounted on a common framework.
In addition, it is preferred in the exclusive-use supporting-roll CCM that both of the common frameworks be provided with a transmission machanism with oscillation power therein, the mechanism being coupled with and un-coupled from a motor which generates the oscillation power with the aid of a coupling-changing cylinder which is fixed on a stationary base.
In the CCM of the present invention, each of the supporting-roll assemblies usually comprises at least one pair of first rolls which support at least the long sides of a beam blank and a rectangular strand. The supporting method carried out in the CCM is hereinafter referred to as the supporting method of the present invention.
ccording Jo an embodiment of the supporting method of the present invention, the supporting-roll assemblies com-prise, as seen in the casting direction: tax an eigh-~sided ~2~S~
' - 6 -:
supporting-roll assembly which consists of a pair of support-ing rolls for supporting the web o:E a beam blank, two pairs of supporting rolls for supporting exclusively the -tip surfaces of the rlanges oE a beam blank, and a pair of supporting rolls for supporting the lateral surEaces of the flanges of a bleam plank; (b) four-sided supporting-roll I, assembly which consists of a pair of supporting rolls for supporting the lateral surfaces of the flanges of a beam blank and a pair of supporting rolls for supporting at least the web of a beam blank; and (c) a two-sided supporting-roll assembly which consists of a pair of supporting rolls for supporting at least the upper and lower flange surfaces of a beam blank, a rectangular strand being supported by the supporting rolls of the eight-, four, and two-sided support-ing roll assemblies except for those suppor-ting exclusively I, .
the tip and lateral surfaces of the flanyes of a beam blank.
According to a preferred embodiment of the CCM of the present invention for carrying out the suppor-ting method of the present invention, the CCM of the present inven-tion comprises a plurality of segments, each segment having a plurality of supporting-roll assemblies arranged in the casting direc-tion and being disposed in a single frame.
The present invention is hereinafter explained with reference to the drawings.
25In the drawings:
figure 1 schematically illustrates a CCM according to the present invention;
Figs. 2A through 2D schematically illustrate the , ~2q~5~

supportln~ method of the present invention with regard to a beam blank;
Fig. 3 schematically illustrates the solidification of a beam blank;
Fig. 4 schematically illustrates the supporting method of the present invention with regard to a slab;
Fig. 5 shcematically illustrates an ernbodiment of the total combined-use supporting-roll CCM;
Figs. fiA through 6C and Figs. 7A through 7C schema-tically illustrate the supporting method of the present invention carried out in the CCM of Fig. 5;
Fig. 8 schematically illustrates an embodiment of the exclusive-use supporting-roll CCM;
Figs. 9 through 11 are plan views of a four~sided supporting-roll assembly;
Fig. 12 is a top fron-t view of an exclusive-use supporting-roll CCM;
Figs. 13 and 14 schematically illustrate the supporting method of the present invention carried ou-t in the CClvl in Fig. 12;
Figs. 15A through 15C, 16A through 16C, 17A and 17B, 18A and 18B, l9A through 19C, and 20A through 20C
schematically illustrate the F-side fixing-supporting method of the present invention; and Figs. 21 and 22 are top plan views of a F-side fixing-supporting-roll assembly.
In FigO 1, a CCM according to the present invention is schematically illustratedO A mold is denoted by reference numeral 2 and a beam blank is denoted by reference nurneral 8.
A suppor-ting-roll assembly comprises supporting rolls 11 for supporting the lateral surfaces of the flanges of a beam blank (hereinafter referred to as the flange lateral-surface supporting rolls 11), supporting rolls 14 for supporting the Deb of a beam blank (hereinafter referred to as the web-i -supporting rolls 14), supporting rolls 13 for supporting exclusively the tip surfaces of the flanges of a beam blank (hereinafter referred to as the exclusive tip-surface supporting rolls 13, and supporting rolls 17 for supporting the up~r and lower flange surfaces of a beau blank (herein-after referred to as the upper and lower flange-surface supporting rolls 17).
As is described hereinbelow, not all of said supporting rolls 11, 13, 14, and 17 are brought into contact with a slab.
In the zone of the CC~I denoted by (I), eigh-t-sided supporting-roll assemblies, one of which is shown in Fig. 2A, are disposed. Similarly, four-sided supporting--roll assem-blies (shown in Fig. 2B and Fig. 2C) and a two--sided support-ing-roll assembly (Fig. 2D) are disposed in the zones of the CC~ indicated by ~II) and (III), respectively. Reference numeral 7 i.ndicates a header for cooling strands.
The eight-sided supporting-roll assembly shown in Fig. 2A is necessary for maintaining the shape of the beam blank 8, which contains a thick unsolidified por-tionO when the unsolidified portion of the beam blank 8 decreases, the four-sided supporting-roll assemblies shown in E'igs. 2B

4~74 _ 9 _ and 2C are consecutively used for supporting -the beam blank 8, and when there is appreciably no unsolidified portion or complete solidification has taken place in the beam blank 8, the two sided-supporting-roll assembly shown in Fig. 2D is used for supporting the beam blank 8. lore specifically, in the beam blank 8 shown in Fig. 3, the fillet portions 100 ;~ include unsolidified metal 8a, and, as is well known, solidi-fication occurs very late ln the fillet portions 100. In accordance with solidification in the fillet portions 100, ; 10 the arrangemen-t of the types of supporting-roll assemblies is determined so tha-t the eigh-t-sided, four-sided, and two-sided supporting roll assemblies (Figs. 2A through 2D) are consecutively arranged in the CCM. Incidentally, since the progress of solidification in the fillet portions 100 can be rather accurately estimated based on the temperature of the molten steel, the casting steed, the cooling speed and other casting parameters, the eight-sided, four-sided, and two-sided supporting-roll assemblies can be appropriately arranged in the CCM.
In Fig. 1, the beam blank 8 is cast in accordance with a predetermined radius of curve and is straightened linearly by unbending rolls disposed in the two-sided supporting-roll assembly of the zone (III). The straightened beam blank is cut into beam blank sections having a predetermined length and then the beam blank sections are successively subjected to the next step, for example temperature-holding in a holding furnace and heating in a heating furnace, and then to the rough- or finishing-rolling step.

5'~

A single supporting-roll assembly or a plurality ox supporting-roll assemblies arranged in the casting direction may be disposed in a single frame so as -to construc-t segrnen-ts, thereby simplifying replacemant of the supporting-roll 5 assemblies, as is well known.
In Fig. 2, the exclusive tip-surface supportiny rolls 13, the web-supporting rolls 14, and the upper and lower flange--surface-supporting rolls 17 are the first rolls which support the lony sides of the beam blank 8, and the flange lateral-surface supporting rolls 11 are the second rolls which support the short sides of the beam blank 8.
ccording to an embodiment of the supporting method of the present invention, one pair of the first rolls, for example, the web-supporting rolls 14 (Fits. and 4B) or 15 the upper and lower flange-surface supporting rolls 17 (Figs. 4C and 4D), support a slab ~0. Incidentally, Figs. 4A through 4D correspond to Figs. 2A through 2D, respectively, concerning the portion of the CCM where the respective supporting-roll assemblies are installed.
In the total combined-use supporting~roll CCM shown in Fig. 5/ the supporting-roll assemblies in the Jones (I), (II~, and (III) are in the form of two, fiYe, and four segments, respectively. These segments are denoted by 25a through 25ko The strand is cut in-to pieces (only one piece 27 is shown), 25 by a cutting device 26 and the cut pieces are transferred to the next step by a transferring table 28~
Reference numeral 2a indicates the pouriny position where continuous casting is started by using a beam-blank ~L20d~5~

casting mold 2b or a slob casting rnold 2c. When the con-tinuous casting of a beam blank (not shown) is completed, the beam-blank casting mold 2b is displaced by a displacing device (not shown), such as a crane, a rail, or a turntable.
subsequently, the slab casting mold 2c is displaced to the pvuring position 2a by displacing device (not shown) and engaged with and fixed to an oscillation mechanism and a stationary frame (not shown), respectively. Continuous casting of a slab is then initiated.
In Figs. 6A, 6B, and 6C, the process of continuously casting a beam blank 8 is schematically and partially illus-trated. The beam-blank casting mold 2b is a split-type casting mold and includes cooling-water circulating channels 19. The supporting-roll assembly in the segment 25a ls, as shown in Fig. 6B, an eight-sided supporting-roll assembly. ? The supporting-roll assemblies in the segments 25h through 25k are, as shown in Fig. 6C, two-sided supporting roll assemblies. In the CC~ for casting the beam blank 8 having a low web height, the web-supporting rolls 14 (Fig. ~B) are short. The supporting of a wide slab only by means of the web-supporting rolls 14 is therefore rather difficult but is possible especially when the exclusive tip-surface supporting rolls 13 are used in addition to the web-support-ing rolls 14.
In Fig. 7A, the slab-casting mold 2C is illustrated and is a built-up mold composed of two long-sided and two short-sided plates. The slab 80 which is continuouly cast in the slab-casting mold 2C is supported by the exclusive 5~7~

tip-surface supporting rolls 13 and the web-supportiny rolls 14, as shown in Fig. 7B. In Fig. 7B', it is illus-tra-ted that when -the web heigh-t of the beam blank 8 (Fiys. 2 and 3) is great, and the web-supporting rolls 14 are long enough, the web-supporting rolls l can be used alone to support the slab 80. The slab 80 shown in Fig. 7~ is not shown on the same reduced scale as in Fig. 7B'.
In the experiments carried out by the inventors, beam blanks having the foilowing dimension were continuously cast 0 at a casting speed of one meter per minute.
~kb height : 1030 mm Flange width : 450 mm Web width : 135 mm Width of tips of flanges : 110 mm When the total weight of the continously cast beam blanks aMounted to 2,000 tons, the beam-blank casting mold was replaced with a slab casting mold, as illustrated in Figs. 5 through 7, and 2,100 tons of slabs were continuously cas-t a-t a casting speed of 1.25 meters per minute. During continuous casiing, the supporting-roll assemblies operated satisfactorily, and there were no accidents. The slabs had a width of 560 mm and a thickness of 250 mm.
The idea of optionally producing different kinds of strands, i.e., a beam blank and a rectangular strand, by jeans of a single CCM has not previously been conceived in the art of continous casting since, from a technically established theory, it is recognized that it is favorable to design the short web-supporting rolls 14 of an eight-sided `` ~Z0~579~

supporting-roll assembly (Fig. 6B) so that they have-a length of 200 mm or less as is well known. when the long web-supporting rolls 14, shown in Fig. 2B, having a length of from 400 to 700 mm are used in the CCM of the present invention, both a beam blank and a rectangular strand can be produced by means of a single CCM, as illustrated in Figs. 6 and 7, such production being extremely economical. In addition, it is also possible to produce by means of a single CCM both a huge beam blank having a web height of from 600 to 1200 mm and which has no-t previously been con-tinuously cast and a slab having a width of from 400 to 700 mm.
In the CCM of the resent invention in which the supporting rolls of one or several of the segments support lS exclusively ei-ther a beam blank or a rectangular strand, said one o`r several segments for supporting the beam blank can be replaced by those for supporting the rectangular strand and vice versa. It is, therefore, possible to pro-duce every kind of strand in a single CCM. Nevertheless, when the supporting rolls of two or more of the segments support exclusively either a beam blank or a rectangular strand, the time required for replacement of the segments is too long for the casting of different kinds oE strands to be practically carried out.
In Fig. 8, an embodiment of the exclusive-use support-ing-roll CCM is illustrated. When the supportirlg-roll assemblies 23 and 24 are displaced so that they are directly below the mold of the pouring position 2a, they exclusively ` ~ZO'~5i7~

support a beam blank or a slab. Segments 25a through 25j are arranged in the casting direction, and a plurali-ty of supporting-roll assemblies is disposed in each of khe segments so as to attain convenient mounting, replacing, repairing, and maintaining of the supporting-roll assemblies.
The supporting-roll assemblies include: so-called apron rollers, i.e., supporting rolls which are arranged directly below the mold, are spaced a short distance from each other, and define a forced-cooling zone; pinch rolls for imparting a withdrawal force to strands; guide rolls for guiding strands; straightening rolls for bending strands linearly;
and so-called compression casting rolls for preventing cracks in strands. These various kinds of rolls are not specifically described herein but are briefly illustrated in the segments 25 for the sake of brevity.
When a beam blank is continuously cast in the exclusive--use supporting-roll CCM of Fig. 8, the beam-blank casting mold 2b is directly connected to the supporting-roll as-sembly 23 for supporting the beam blank, and the beam-blank casting mold 2b and the supporting-roll assembly 23 are simultaneously transferred to the pouring position 2a. The supporting-roll assembly 23, which is located directly below the beam-blank casting mold 2b, is an eight-sided supporting -roll assembly, as shown in Fig. 2A, and firmly supports a beam blank in such a manner that the beam blank has a good shape and quaIity. The types of supporting-roll assemblies are varied in accordance with a decrease in the unsolidified portion (Fig. 3, 8a3 of a beam blank, i.e., a beam blank is `- ~L2~S7'1 consecutively supported by four-sided supporting-roll as-semblies such as those shown in Figs. 2B and 2C, as well as by a two-sided sup~orting-roll assembly such as that shown in Fig. 2D. Four-sided supporting-roll assemblies such as those shown in Figs. 2~ and 2C can be used in the seg-r,lenks 25a through 25e, and a two-sided supporting-roll assembly such as that shown in Fig. 2D can be used in the segments 25f through 25j.
A pair of first rolls, for example the web-supporting rolls 14, and a pair of the upper and lower flange-surface supporting rolls 17 are retractable in a traversal direction in relation to the axis of the beam blank 8 so that one of the first rolls advances toward and retracts from one of the sides of the beam blank 8 or the pair of first rolls advances toward and retracts from the sides of the beam blank 8.
Embodiments of the four-sided supporting-roll assembly in which the pair of first rolls are retractable as stated above, are illustrated in Figs. 9 and lO. In Fig. 9, the four-sided supporting-roll assembly 30 comprises flange lateral-surface supporting rolls 35 which are brought into rotatable contact with the lateral surfaces of the beam blank 8 and support the beam blank 8. The flange lateral--surface supporting rolls 35 are supported by bearing stands 38 which are secured on frames 39. The frames 39 are engaged with screw devices 40 via retractably actuated shafts 41.
Worm devices 42 are engaged with worm shafts 43 which are actuated by driving devices snot shown). The shafts 41 are therefore advanced and retracted by the worm shafts 43, the `- lZ04S~4 worm devices 42, and the screw devices 40 so that the shafts 41, which are secured to the frames 39, determine the posi-tion of the flange lateral-flange surface supporting rolls 35.
Similarly, web-supporting rolls 34 are supported by bearing s-tands 44 which are secured on frames 45. The frames 45 are engaged with screw devices 48 via retractably actuated shafts 46. Worm devices 47 are engaged with worm shafts 49 which are actuated by driving devices (not shown).
The shafts 46 are thereforè advanced and retracted by the worm shafts 49, the worm devices 47, and the screw devices 48 so that the shafts 46, which are secured to the frames 45, determine the position of the web-supporting rolls 34.
The worm devices 42 and 47 and the screw devices 40 and 48 are supported by stationary frames 51 and 50 which are connected to one another by bolts (not shown). In the four-sided supporting-roll assembly 30 shown in Fig. 9, the flange lateral-surface supporting rolls 35 are retractable.
However, the flange lateral-surface supporting rolls 35 may be stationarily arranged in the ~our-sided supporting-roll assembly 30, such a stationary arrangement occasionally being preferably from an economical pvint of view, depending upon the size of the beam blank 8, especially when the size of the beam blank 8 is not changed in consecutive casting procedures.

An embodiment of the stationary arrangement of the flange lateral-surface supporting rolls 35 is illustrated in Fig. 10 in which, for the sake of simpllcity of description9 the beam blank 8 and the slab 80, which are guided by or 57~L

withdrawn by the four-sided supporting-roll assembly 30, are shown on the left side and the right side of the drawing, respectively, along the line A-A. The same parts of the four-sided supporting-roll assembly as that in Fig. 9 are denoted by the same reference numerals. The flange lateral--surface supporting rolls 35 are rotatably in contact with the flange surfaces of the beam blank 8 and support the beam blank 8. The bearing stands 38 are connected to the station-ary frames 51 so that the flange lateral-surface supporting rolls 35 are not retractable, i.e., they are stationary.
The short sides of the slab 80 are not supported by the flange lateral-surface supporting rolls 35. The web-support-ing rolls 34 are brought into contact with the web of the beam blank 8 having any dimension as well as the long sides of the slab 80 having any dimension, and, therefore, the beam blank 8 end the slab 80 are supported and guided by the web~supporting rolls 34. The structure of the four-sided supporting-roll assembly 30 shown in Fig. 10 can be fabri-I` cated at a low cost. Since there is no need to support the short sides of the slab 80, the supporting-roll assemblies are positively pxovided with such a structure that the rolls arranged at the short sides of a strand are stationary, this being economically advantageous In Fig. 11, a four-sided supporting roll assembly 30 similar to that of Fig 9 is illustrated, and the upper and lower flange-surface supporting rolls 17 of said assembly are retractableO The same parts of the four-sided support-iny~roll assembly 30 as those in Fig. 9 are denoted by the same reference nurnerals.
An embodiment of the exclusive-use supporting-roll CC~
is now described in regard to how the mold and the support-iny-roll assembly provided directly below the mold are interchangeably arranged in said CCM so as to attain easy and quick changing of different kinds of strands. In Fig. 12, the beam-blank casting mold 2b, an eight-sided supporting--roll assembly 67 whlch is arranged subsequent to the beam--blank casting mold 2b and which exclusively supports a beam blank, and a four-sided suppor-ting-roll assembly 77 which supports both a beam blank and a rectangular strand are schematically illustrated. The beam-blank casting mold 2b is mounted on a mold-oscillation table 63 via a mold-support-ing frame 62. The mold-oscillation table 63 is oscillated by eccentric cams 64 which generate an oscillating movement, and the eccentric cams 64 are ac-tuated by an oscillation--power transmitting shaft 65 and an oscillation-power transmitting gear device 66. The eight-sided supporting-roll assemhly 67 is arranged in such a manner that its top end is adjacent to the beam-blank casting mold 2b and is slidably supported by and fit into the mold~supporting frame 62. The eight-sided supporting roll assembly 67 can therefore be displaced in the direction of oscillation of the beam-blank casting mold 2b. The lower end of the eight-sided support-ing-roll assembly 67 is movably fit into a supporting base snot shown) which is fixed to a common framework 68.
The eight-sided supporting-roll assembly 67 is therefore capable of swinging around its lower end does not impede 5~

the oscillating movement of the mold-oscillation table 63 at all In addition, thy cornmon framework 68 is remo-vably fixed to a base frame 69. A stopper 70 rigidly engages the common framework 68 and the base frame 69.
The common framework 68 is coupled to a power-trans-mission mechanism, a clamp device, and a cooling-water conduit coupling which are described hereinbelow and which are uncoupled from the common framework 68 upon completion of continuous casting of a beam blank. After the uncoupling described above, a hanger 72 is engaged around pins 71 provided on the common framework 68, and the hanger 72 is then lifted up by means of a hook 73 of an overhead travel-ling crane (not shown), with the resul-t that the common framework 68, on which the beam-blank casting mold 2b, the eight-sided supporting-roll assembly Ç7, and the above described~means for oscillating the mold are mounted, is lifted up. The common framework 68 is then transferred to a predetermined position where it remains in a s-tandby con-dition until the next casting procedure. Alternatively, repair of the members mounted on the common framework 68 can be effected. A slab-casting mold and supporting rolls mounted on a common framework (not shown in Fig. 12) are transferred from a standby position to a puring position, and the common framework is fixed to the base frame 69.
Immediately after adjusting the roll distance of the four-sided supporting-roll assembly 77 and the succeeding supporting-roll assemblies (not shown), the continuous casting of a slab can be initiatedO

7'~

Thé me~oers of the CC~I for sup,vorting a slab are the same as those for supportiny a beam blank except for the two-sided roll assembly provided directly below the slab-casting mold. Therefore, description of the members is omitted.
A cross-sectional view of the exclusive tip-surface supporting rolls 13 of Fig. 2~ and the web-supporting rolls 14 of Fig. 2A is shown in Fig. 12, the rolls 13 and the rolls 14 being denoted in the fiyure by 74 and 75, re-spectively. number of the exclusive tip-surface supporting rolls 74 and the web supporting rolls 75 are arranged a short distance from each other, such arrangement being preferable for maintaining the shape of a beam blank and preventing break-out.
The four-sided supporting-roll assembly 77 is used for both a beam blank and a slab. The web-supporting rolls 14 of Fig. 2B are denoted in Fig. 12 by 78. The four-sided supporting-roll assembly 77 is in the forrn of a segment and is disposed in a single frame 76. The single frame 76 is removably secured to a machine frame 99 by metal fittings 79 so as to simplify repair of the four-sided supporting-roll assembly 77. The machine frame 99 is engaged with a base beam 82 via a fitting 81. The web-supporting rolls 78 are retracted and advanced in a traversal direction in relation to the axis of a strand by a screw device 83 which is mounted on the outer side of the single frame 76. The screw device 83 includes a driving shaft 84 and a driving hydraulic motor 85. The web-supporting rolls 78 are retracted and advanced as stated above and are thus displaced at an appro-priate positlon in accordance with the web width or the slab width.
cooling-water conduit coupling 86 is communicated with a cooling-water channel (no-t shown) formed in the common framework 68. The cooling-water conduit coupling 86 is displaced by a cylinder device 87 which is placed on a stand 88 so as to disconnected and connect the cooling-water path when installing and withdrawing the common framework 68, respectively. The power-transmission mechanism includes an oscillation-power generating motor 90 placed on a stand 94, a transmission shaft 91, and a transmission-shaft coupl-ing device 89. Oscillating power is transmitted via the transmission-shaft coupling device 89 to the beam-blank casting mold 2b. When the common framework 68 is replaced so as to change kinds of strands, a coupling-chaning cylinder 93 which is mounted on a stationary base 92 is actuated so as to uncouple and then couple the transmission--shaft coupling device 89 with respect to the oscillation power transmission mechanism (not shown) provided in the common framework.
In Fig. 13, the slab 80 is supported by the pair of supporting rolls 37 of the two-sided supporting-roll assembly which is provided directly below the slab-casting mold and

2~ which is disposed on a common framework (not shown). The two-sided supporting-roll assembly mentioned above can easily and promptly replace the four-sided supporting-roll assembly provided in the common framework 68 (Fig. 12~.

~Q~

In Fig. 14, the web-supporting rolls 78 of the four-sided supporting-roll assembly 77 suppor-t the slab 80.
According to an embodiment of the CCM of the present invention, in a pair of supporting rolls for interchangeably supporting different kinds of strands, the pair of supporting rolls consists of a fixed side roll and a loose side roll, said fixed side roll which is brought into contact with the fixed side of a strand being rotatably supported by a bearing which is stationarily mounted on a supporting frame. The fixed side and the loose side of a strand are hereinafter referred to as the F side and the L side, respectively.
When a beau blank and a rectangular strand are of a different dimension, a four-sided or two-sided supporting-roll assembly in which several supporting rolls, for example, upper and lower flange-sur~ace supporting rolls, are used for support-ing both the beam blank are the rectangular strand must be provided with a means for optionally changing the position of the supporting rolls. Installation and maintainance of -this means are, however, expensive. In addition, preparation for the casting procedure becomes long since roll alignment of the supporting-roll assembly is rather complicated. In the zone (II) of the CCM figs. 1 and 5), roll alignment is especially complicated since a pair of the web-supporting rolls l (Fig. 2B) must be displaced for carrying out roll alignment. Furthermore, the preparation time is even longer when a supporting-roll assembly of the zones ~II) is xeplaced so as to change different kinds of s-trandsO
In the supporting method of the present invention illustrated in Figs. 15A through 15C and Figs. 16A through 16C, the eight-sided supporting roll assemblies (Fiys. 15A
and 16~) and the four-sided supporting~roll assemblies arranged in the zone (I) (Figs. 1 and 5) are interchangeable.
However, the four-sided supportin~-roll assembly (Figs. 15B
and 16~) arranged in the zone (II) (Figs. 1 and 5) is used for supporting both the beam blank 8 and the slab 80. on F
side roll 14f of the pair of the web-supporting rolls 14 (Figs. 15B and 16B) is stationary and only the L side roll 14Q is displacable so as to change its position relative to the F side roll 14f. Incidentally, the F side indicates the lower side of a strand as it is guided to a horizontal position, as is well known. The four-sided supporting-roll assembly (Fig. 16A) for supporting the slab 80 consists of a pair of the long-sided supporting rolls 9 and a pair of the short-sided supporting rolls 19. The flange lateral-surface supporting rolls 11 of the four-sided supporting roll as-sembly (Figs. 15B and 16B) may be stationary.
The supporting-roll assemblies arranged in the zone (III) (Figs. 1 and 5) consist of a pair of rolls whose diameter is the greatest at the central portion thereof.
These rolls are hereinafter referred to as central large -diameter rolls 95f and 95Q. The tip surfaces and the web of the beam blank 8 are supported by a pair of the central ~5 large-diameter rolls 95f and 95Q. The design of the rolls of a rolling mill can be greatly simplified since, according to recently developed techniques, various kinds of steels can be produced by using one format of a beam blank In ~2~4~7~

this case, it is preferable to use the central large-diameter rolls 95f and 95Q to support the beam blank 8. In order to support the slab 80 (Fig. 16C) by using the cen-tral large--diameter rolls 95f and 95Q, the central portions of these rolls are rotably brought into contac-t with the slab 80.
The central large-diameter roll 95f at the F side is stationary while the central large-diameter roll 95Q at the F side is displacable and is displaced so that it engages the F side of the beam blank 8 (Fig. 15C) and the slab 80 (Fig. 16C).
In Figs. 17A and 17B, another embodiment of the two--sided supporting roll assembly arranged in the zone (III) (Figs. 1 and 5) is illustrated. A pair of supporting rolls consists of an upper flange-surface supporting roll 17Q at the L side and a central large-diameter roll 95f at the F side. wince solidification of the molten metal is almost complete in the zone (III~, it is not necessary to positively support the web of the beam blank at the L side thereof, and therefore not the central large-diameter roll but the upper flange-surface supporting roll 17Q is used in the zone III (Figs. 1 and 5). The central large-diameter rolls 95f and 95Q (Figs. 15C and 16C) can be manufactured by casting, machining, or shrinkage fitting. However, these rolls are expensive as compared with a flat roll such as the web-supporting rolls 17 (Figs. 2C and 2D)o It is, therefore, preferable, as can be seen from Figs. 15C and 16C as well as FigsO 17A and 17B, to replace central large~diameter rolls with as many flat rolls as possible depending on the progress so of solidification.
In Figs. 18A and 18~, an embodiment of a six-sided supporting-roll assembly arranged in the zone (III) (Figs. 1 and 5) is illustrated. Usually, the zone (III) (E'igs. 1 and 5) is the zone of a CCM where strands are straightened and where the supporting-rolls are designed so as to satis-factorily resist the reaction force of strands being straightened. Therefore, when the central large-diameter rolls 95f and 95Q (Figs. 15C and 16C) are used in the zone (III) (Figs. 1 and 5), their roll bodies 97f and 97Q oc-casionally have a large diameter, a large diameter being uneconomical. In additiGn, when the diameter of the roll bodies 97~ and 97Q becomes large, the distance between the supporting rolls as seen in the withdrawal direction of a strand becomes great, with the result that the straightening of an unsolidified strand may result in bulging of the strand and deterioration of the qualities of the strand.
Therefore, it is sometimes very advantageous, depending upon the format of a strand and the casting conditions, to employ a six-sided supporting-roll assembly arranged in the zone (III~ (Figs. 1 and 5) to support the beam blank 8, in which assembly a portions OL the supporting rolls for supporting the tip surfaces and the web of the beam blank 8 are not integral but are separated as shown in FigO 18A~ lore specifically, the supporting-roll assembly in which portions of the supporting rolls for supporting the tip surfaces and the web of the beam blank 8 are integral must be so designed that roll necks 98f and 98Q, (Fig. 15C), which are in contact 7~

with the tip surfaces of the beau blank 8 and additionally support the workpiece, have a diameter enabling thern to resist the reaction force of a strand being straightened.
Therefore the diameter of the roll bodies 97f and 97Q must be determined univocall~, that is, said diameter mus-t be the swn of the diameter of the roll necks 98f and 98Q and the flange-tip width, i.e., the difference between the flange width and the web width. In addition, the roll body and the roll neck of the central làrge-diameter rolls 95f and 95Q
are designed to be coaxial with respect to one another.
because of the design of the central large-diameter rolls 95f and 95Q as explained above, the diameter of the roll bodies 95Q and 97f becomes great. Contrary to such great diameter of the roll bodies 97Q and 97f which increases the dimension of the central large-diameter rolls as a whole, the diameter of the web supporting rolls 14 and the tip-surface supporting rolls 13 is very appropriately determined in respect to their resistance to the reaction force of a strand being straightened. In addition, each web-supporting roll and tip-surface supporting roll arranged at either the F side or the L side may not be coaxial. Therefore, the six-sided supporting-roll assembly shown in Fig. 18A is advantageously arranged in the zone (III) (Figs. 1 and S) depending upon the format of the strands and the casting conditions.
When the rolls at the F side of two-and four-sided supporting-roll assemblies are stationary, the distance between a pair of rolls, i.eO, a roll at F the side and a roll at the L side, can ye adjusted simply by displacing the roll at the L side, with the result that the productivity of continuous casting can be drastically enhanced since the period of preparation for continuous casting and the time necessary for changing different kinds of strands are shortened. In addition, when the eight-sided supporting-roll assembly 67 (Fig. 12) is so designed that the supporting rolls at the F side and the L side are stationary and dis-placable, respectively, the eight-sided supporting-roll assembly 67 is used for interchangeably supporting a beam blank and a rectangular strand and thus productivity can be enhanced. however, the installation cost of such eight-sided supporting-roll assembly is rather high.
In Figs. 19~ through l9C and 20A through 20C, an embodi-ment of the supporting-roll assemblies for supporting the beam blank 8 and the slab 80, respectively, is illustrated.
The supporting-roll assemblies shown in Figs. l9A and 20A
are similar to the supporting-roll assemblies shown in Figs. 15A and 16A in that they are interchangeable. The supporting toll assemblies shown in Figs. 19B and l9C are arranged in the zones II or III figs. 1 and 5) and support the beam blank 8 by means of the central large-diameter rolls 95f and 95Q, as shown in Figs. l9B and lSC. The supporting-roll assemblies shown in Figs. 20B and 20C are identical to those shown in Figs. l9B and l9C, respectively and support the slab 80 by means of the central large-diameter rolls 95f and 95Q. In these supporting=roll assemblies (Figs. 19~, l9C, 20B, and 20C~, the central large-diameter rolls 95f arranged at the F side can be 5~

stationary while the central large-diameter rolls 95Q
arranged at the L side can be displaced and their position can be adJusted relative to a strand. r~hese supporting-roll assemblies are advantageous in that they are few in number.
A further detailed description of the supporting-roll as-semblies of Figs. l9C and 20C is omitted because they are similar to those shown in Figs. 15C and 16C, respectively.
In Fig. 21, an embodiment of a four-sided supporting--roll assembly is shown, and beam blank and a slab supported by this assembly are shown on the left side and the right side, respectively, of the drawing along the line A-A. The web-supporting roll 14Q at the L side is rotatably supported by the bearing stands 44 which are secured to the frame 45.
The frame 45 is movably connected to the screw device 48 which is actua-ted by the worm shaft 49 via the worm device 47O
~Ihen the worm shaft 49 is driven by a driving device (not shown, the web-supporting-roll 14Q at the L side is dis-placed to an optional position relative to the web-sup,~orting roll 14f at the F side. The web-supporting roll 14f at the F side is stationarily secured on the stationary frame 50 via the bearing stands 44. The flange lateral-surface supporting rolls 11 are stationarily secured on the station-ary frames 51 via the bearing stands 38. The stationary frames 50 and 51 are members of the segment and are inte-grally constructed by welding or fixing with bolts. In thefour-sided supporting-roll assembly shown in Fig. 21, both the beam blank 8 and the slab 80 can be supported simply by displacing the ~eb-supporting roll 14Q at the L side so that ~3~

not only a reduction in the installation cost but also an outs-tanding improvement in the operability of the supporting--roll assembly can be attained.
In Fig. 22, the structure of the supporting-roll as-sembly shown in Flgs. 15C, 16C, 13C, or 20C is illustrated in detail and a beam blank and a slab supported by this assembly are shown on the right side and the left side, respectively; of the drawing along the line A-A. The central large-diame-ter roll 95Q at the L side is rotably supported by bearing stands 110 which are provided on a movable frame 109. The movable frame 109 is reciprocably mounted on vertical columns 120 via screw devices 108. The central large-diameter roll 95f at the F side is rotatable supported by bearing stands 112 provided on a stationary frame 111. A
driving shaft 113 is driven by a driving device (not shown) and vertically displaces the movable frame 109 via a coupling 114, a worm device 115, and a screw device 10~ so that the position of the central large-diameter roll 95Q at the L side is adjusted relative to the central large-diameter roll 95f at the F side. Both the beam blank 8 and the slab 80 can therefore be easily supported by one type of supporting-roll assembly in which the roll bodies 97f and 97 are redily interchangeable.
As described hereinabove in detail, different kinds of strands, to a beam blank and a rectangular strand, can be more economically and effectively produced in the CCM of the present invention as compared with the conventional CCMs~
Such production can be made even more economical and the S'7'~ `

installa-tion cost of a CCM is made low when not all the supporting rolls bu-t several main rolls are retractable so as to support different kinds of strands. The CCM of the present invention is very beneficial in respec-t to the economical production of sections and sheets.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. An apparatus for the continuous casting of steel comprising a mold and a plurality of supporting-roll assemblies which are arranged subsequent to said mold, characterized in that: at least one supporting-roll assembly is combined-use assembly capable of supporting a rectangular strand in addition to a beam blank.

2. An apparatus as defined in claim 1 wherein said apparatus comprises a non-combined use supporting roll assembly for supporting either a beam blank or a rectangular strand, said apparatus further comprises a mold for casting specifically either a rectangular strand or a beam blank, the mold being compatible with said non-combined-use supporting-roll assembly, the non-combined-use supporting-roll assembly and the associated mold thereto for producing a beam blank being replaceable by a non-combined-use supporting-roll assembly and the associated mold thereto for producing a rectangular strand and vice-versa thereby allowing the production of a rectangular strand in addition to a beam blank by means of a single continuous casting apparatus.

3. An apparatus according to claim 1, wherein all the supporting-roll assemblies are capable of supporting a beam blank and a rectangular section.

4. An apparatus according to claim 1 and comprising supporting-roll assembly provided directly below the mold and supporting exclusively either a beam blank or a rectangular strand; the supporting-roll assembly provided directly below the mold for supporting a beam blank being replaceable by a supporting-roll roll assembly for supporting a rectangular strand and vice-versa, the supporting-roll assemblies which are arranged subsequent to the supporting-roll assembly directly below the mold are combined-use assemblies which are capable of supporting a rectangular strand in addition to a beam blank.

5. An apparatus according to claim 4, wherein the mold and the supporting-roll assembly, directly below the mold, for supporting a beam blank are mounted on a common framework and, further, the mold and the supporting-roll assembly, directly below the mold, for supporting a rectangular strand are mounted on a common framework.

6. An apparatus according to claim 5, wherein both ox the common frameworks are provided with a transmission mechanism with oscillation power therein, the mechanism being coupled with and uncoupled from a motor which generates the oscillation power with the aid of a coupling-changing cylinder which is fixed on a stationary base.

7. An apparatus according to claim 1, wherein each of the supporting-roll assemblies comprises at least one pair of first rolls which supports at least the long sides of a beam blank and a rectangular strand.

8. An apparatus according to claim 7, wherein said first rolls are web-supporting rolls.

9. An apparatus according to claim 7, wherein said first rolls are a pair of supporting rolls for supporting the upper and lower flange surfaces of a beam blank.

10. An apparatus according to claim 7, wherein said first rolls are three pairs of supporting rolls for supporting the web and the tip-surfaces of a beam blank, and a rectangular strand is supported by said three pairs of supporting rolls.

11. An apparatus according to claim 7, wherein said supporting-roll assemblies comprise second rolls for supporting the flange lateral surface of beam blank.

12. An apparatus according to claim 11, wherein said second rolls are capable of supporting a rectangular strand.

13. An apparatus according to claim 7, wherein the supporting-roll assemblies comprise, as seen in the casting directions: (a) an eight-sides supporting-roll assembly which consists of a pair of supporting rolls for supporting the web of a beam blank, two pairs of supporting rolls for supporting exclusively the tip surfaces of the flanges of a beam blank, and a pair of supporting rolls for supporting the lateral surfaces of the flanges of a beam blank; (b) a four-sides supporting-roll assembly which consists of a pair of supporting rolls for supporting the lateral surfaces of the flanges of a beam blank and a pair of supporting rolls for supporting at least the web of a beam blank;
and (c) a two-sides supporting-roll assembly which consists of a pair of supporting-roll for supporting at least the upper and lower flange surfaces of a beam blank, a rectangular strand being supported by the supporting rolls of the eight-, four-, and two-sides supporting roll assemblies except for those supporting exclusively the tip and lateral surfaces of the flanges of a beam blank.

14. An apparatus according to claim 13, wherein segments, each segment having a plurality of said supporting-roll assemblies, are arranged in the casting direction and are disposed in a single frame.

15. An apparatus according to claim 13, wherein a screw device for displacing the supporting rolls is mounted on the outside of said single frame.

16. An apparatus according to claim 8, wherein the supporting rolls for supporting the web of a beam blank have a length of from 400 to 700 mm.

17. An apparatus according to claim 16, wherein the web height of a beam blank is from 600 to 1200 mm and the width of a slab is from 400 to 700 mm.

18. An apparatus according to claim 7, characterized in that in a pair of supporting rolls for interchangeably supporting different kinds of strands, the pair of supporting rolls consists of a fixed side roll and a loose side roll, said fixed side roll which is brought into contact with the fixed side of a strand being rotably supported by a bearing which is stationarily mounted on a supporting frame.

19. An apparatus according to claim 18, wherein at least one of said pair of supporting rolls, said one supporting roll being arranged at the F side of strands, supports the web of a beam blank by the roll bodies where the diameter is great and supports the tip-surfaces of a beam blank by the roll necks where the diameter is small.

20. An apparatus according to claim 19, wherein the supporting-roll assemblies comprise, as seen in the casting direction: (a) an eight-sides supporting-roll assembly which consists of a pair of supporting rolls for supporting the web of a beam blank, two pairs of supporting rolls for supporting exclusively the tip surfaces of the flanges of a beam blank, and a pair of supporting rolls for supporting the lateral surfaces of the flanges of a beam blank; and (b) four-sides supporting-roll assembly which consists of a pair of supporting rolls for supporting the lateral surfaces of the flanges of a beam blank and a pair of supporting rolls for supporting at least the web of a beam blank;
a rectangular strand being supported by the supporting rolls of the eight-, and four-sides supporting roll assemblies except for those supporting roll assemblies except for those supporting exclusively the tip and lateral surfaces of the flanges of a beam blank.

21. An apparatus according to claim 20, wherein said supporting-foil assemblies further comprises subsequent to said four-sides supporting-roll assembly (b), (c) a two-sides supporting-roll assembly which consists of a pair of supporting rolls for supporting at least the upper and lower flange surface of a beam blank.

22. An apparatus according to claim 21, wherein at least one of said pair of two-sides supporting rolls assembly, said one supporting roll being arranged at the F side of strands, supports the web of a beam blank by the roll bodies where the diameter is great and supports the tip-surfaces of a beam blank by the roll necks where the diameter is small.

23. An apparatus according to claim 20, wherein said supporting-roll assemblies further comprises subsequent to said four-sides supporting-roll assembly (b), a (c) six-sides supporting-roll assembly which consists of a pair of supporting the web of a beam blank and two pairs of supporting-rolls for supporting the tip surfaces of a beam blank.