CA1189281A - Bow-type continuous-casting method and apparatus - Google Patents
Bow-type continuous-casting method and apparatusInfo
- Publication number
- CA1189281A CA1189281A CA000406037A CA406037A CA1189281A CA 1189281 A CA1189281 A CA 1189281A CA 000406037 A CA000406037 A CA 000406037A CA 406037 A CA406037 A CA 406037A CA 1189281 A CA1189281 A CA 1189281A
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- CA
- Canada
- Prior art keywords
- straightening
- rolls
- strand
- bow
- casting
- Prior art date
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
- B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
- B22D11/12—Accessories for subsequent treating or working cast stock in situ
- B22D11/128—Accessories for subsequent treating or working cast stock in situ for removing
- B22D11/1282—Vertical casting and curving the cast stock to the horizontal
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- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Continuous Casting (AREA)
- Mold Materials And Core Materials (AREA)
- Dental Preparations (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
- Casting Devices For Molds (AREA)
- Golf Clubs (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The present invention relates to an improvement in the bow-type continuous-casting method and in the apparatus, the apparatus having a low height, a curved mold (6), and a multi-point straightening zone (10).
The prior art involves a problem in that the straight-ening rolls (7) are not reliable due to a high load which is generated during a non-stationary casting period during which the top or bottom section of a strand (3) is conveyed through a multi-point straightening zone (10).
In the present invention, at least one selected pair of straightening rolls (11) is shunted from the defined radius (Rn) of the curve by means of cone-shaped springs (23) or hydraulic cylinders so that the distance between the two pairs of straightening rolls (11) which are engaged in straightening during a non-stationary casting period is increased. In the present invention, the reliabilicy of the straightening rolls (11) is so enhanced that high-speed and moderate-cooling casting in a low-head CCM can be directly combined with hot-rolling of the strands (3).
The present invention relates to an improvement in the bow-type continuous-casting method and in the apparatus, the apparatus having a low height, a curved mold (6), and a multi-point straightening zone (10).
The prior art involves a problem in that the straight-ening rolls (7) are not reliable due to a high load which is generated during a non-stationary casting period during which the top or bottom section of a strand (3) is conveyed through a multi-point straightening zone (10).
In the present invention, at least one selected pair of straightening rolls (11) is shunted from the defined radius (Rn) of the curve by means of cone-shaped springs (23) or hydraulic cylinders so that the distance between the two pairs of straightening rolls (11) which are engaged in straightening during a non-stationary casting period is increased. In the present invention, the reliabilicy of the straightening rolls (11) is so enhanced that high-speed and moderate-cooling casting in a low-head CCM can be directly combined with hot-rolling of the strands (3).
Description
A BOW-TYPE CONTINUOUS-CASTI_ METHOD AND APPARATUS
The present invention relates to a method for the continuous casting of a high-quali-ty strand with a high production efflciency, as well as to an apparatus fox carrying out the method mentioned above. More particularly, the present invention relates to a bow-type continuous--casting method and apparatus in which a strand i9 stra.ight-ened in a multi-point straightening zone by means of a plurality of pairs of straightening rolls which refine curves having successively increasing radii. Furthermorev particularly, the present invent relates to an improvement in the bow-type continuous-casting method and in -the apparatus, the apparatus having a low height and comprising a multi-point straightening zone, in which pairs of the straightening rolls are successively arranged, the aim of the above method and apparatus being to realize a directly combined continuous-castiny and rolling process (hereinafter referred to as the CD process).
Recently, the CD process has attracted attention because of a reduction in the amount of therma]. energy 20 required to produce hot-rolled products according to this process and because the CD process enables strands :Eormed in a con-tinuous-casting machine and having a high sensible heat to be directly supplied -to a ho-t-rolling mill wi-thout being subjected to cooling, condi-tioning and reheating, and thereby predetermined hot-rolled products are obtained. In order to realize the CD process, the following must be reliably and simultaneously achieved in continuous casting:
(1) the temperature of the strands must be high enough to allow direct hot-rolling; 12) the quality of the strands must be high enough to allow the production of ho-t-rolled products haviny desired qualities regardless of whether or not the strands are conditioned; and (3) the s-trand pro-ductivity must be higher than that of conventional casting so as to compete with the high productivity of a hot-rolling mill.
The present applicant has already proposed new con-tinuous-casting methods and apparatuses so that the above-mentioned (1), (2), and (3) can be effectively achieved. The basic concept of the applicant's proposals involves high-speed and moderate-cooling casting 'carried out in a bow-type continuous-casting machine having a low height and comprising a multi-point straightening zone.
lo More in detail, in the continuous-casting machine according to the applicant's proposals, casting is carried out at a higher speed and more moderate cooling than in the con-ventional, widely used, bow-type continuous-casting machine, in which machine the machine height is 12 m or more, the radius of the curve is from 10 to 13 m, and the straigh-ten-ing of a strand is carried out by means of single unbending or one-point straightening. The casting conditions accord-ing to the applicant's proposals enable surface defects in strands to be prevented and, further, enable high-temperature strands to be produced with a high productivity. The bow-type continuous~casting machine is hereinafter referred to as a bow-type CCM. Bow-type CCMs having hiyh and low machine heights are hereinafter referred to as high-head and low-head CCMs, respectively. The conventional bow-type continuous-casting machine mentioned above is hereinafter referred to as the conventional bow-type CCM.
The problems involved in a high-head CCM are now specifically described.
' If casting is carried out in the high-head CCM at a high speed and moderate cooling, the solidified shell of a strand has such a small thickness that its rigidity is decreased, with the result that a thin solidified shell is subjec-ted to a high ferrostatic pressure due to the high machine height of the high-head CCM. Consequently, the bulging strain, which can cause inner defects in a strand, is increased. If the diameter of the rolls which support a strand is made small and if the distance between these
The present invention relates to a method for the continuous casting of a high-quali-ty strand with a high production efflciency, as well as to an apparatus fox carrying out the method mentioned above. More particularly, the present invention relates to a bow-type continuous--casting method and apparatus in which a strand i9 stra.ight-ened in a multi-point straightening zone by means of a plurality of pairs of straightening rolls which refine curves having successively increasing radii. Furthermorev particularly, the present invent relates to an improvement in the bow-type continuous-casting method and in -the apparatus, the apparatus having a low height and comprising a multi-point straightening zone, in which pairs of the straightening rolls are successively arranged, the aim of the above method and apparatus being to realize a directly combined continuous-castiny and rolling process (hereinafter referred to as the CD process).
Recently, the CD process has attracted attention because of a reduction in the amount of therma]. energy 20 required to produce hot-rolled products according to this process and because the CD process enables strands :Eormed in a con-tinuous-casting machine and having a high sensible heat to be directly supplied -to a ho-t-rolling mill wi-thout being subjected to cooling, condi-tioning and reheating, and thereby predetermined hot-rolled products are obtained. In order to realize the CD process, the following must be reliably and simultaneously achieved in continuous casting:
(1) the temperature of the strands must be high enough to allow direct hot-rolling; 12) the quality of the strands must be high enough to allow the production of ho-t-rolled products haviny desired qualities regardless of whether or not the strands are conditioned; and (3) the s-trand pro-ductivity must be higher than that of conventional casting so as to compete with the high productivity of a hot-rolling mill.
The present applicant has already proposed new con-tinuous-casting methods and apparatuses so that the above-mentioned (1), (2), and (3) can be effectively achieved. The basic concept of the applicant's proposals involves high-speed and moderate-cooling casting 'carried out in a bow-type continuous-casting machine having a low height and comprising a multi-point straightening zone.
lo More in detail, in the continuous-casting machine according to the applicant's proposals, casting is carried out at a higher speed and more moderate cooling than in the con-ventional, widely used, bow-type continuous-casting machine, in which machine the machine height is 12 m or more, the radius of the curve is from 10 to 13 m, and the straigh-ten-ing of a strand is carried out by means of single unbending or one-point straightening. The casting conditions accord-ing to the applicant's proposals enable surface defects in strands to be prevented and, further, enable high-temperature strands to be produced with a high productivity. The bow-type continuous~casting machine is hereinafter referred to as a bow-type CCM. Bow-type CCMs having hiyh and low machine heights are hereinafter referred to as high-head and low-head CCMs, respectively. The conventional bow-type continuous-casting machine mentioned above is hereinafter referred to as the conventional bow-type CCM.
The problems involved in a high-head CCM are now specifically described.
' If casting is carried out in the high-head CCM at a high speed and moderate cooling, the solidified shell of a strand has such a small thickness that its rigidity is decreased, with the result that a thin solidified shell is subjec-ted to a high ferrostatic pressure due to the high machine height of the high-head CCM. Consequently, the bulging strain, which can cause inner defects in a strand, is increased. If the diameter of the rolls which support a strand is made small and if the distance between these
2~
rolls is decreased, an increase in the bulging strain can be prevented. However, such a method for preventing an increase in the bulging strain cannot be employed in the case of the high-head CCM because it is difficult to support by means of small-diameter rolls a strand to which a hiyh ferrostatic pressure due to a high machine height is applied.
In an attempt to reduce the ferros-tatic pressure, such a high machine height as that provided in the conventional bow-type CCM is reduced by one half or less than one half and simultaneously the conventional radius of the curve is decreased by, for example, one half or less than one half, according to the applicant's proposals. In this case, thy unbending of a strand is carried out at a plurality of straightening points since, if conventional single-point straightening were carried out in the case of a s-trand having a small radius, the straightening strain, which can cause inner defects in the strand, would be increased and thus inner defects would frequently occur. In other words, concentration of the straightening strain on one point of the strand is avoided and instead the straightening strain is distributed to a plurality of straightening points in the strand where the straightening strain is made lower than the permissible value.
Z5 In addition to the present applicant, Sumitomo Metals Co., Ltd. has recently proposed a low-head CC~ in which strands having a high material quality can be efficiently produced due to a low machine height.
The prior art is now described with reference to Fig. 1.
In the drawings:
Figure 1 is a schematic vie of a known low-head CCM
comprising a five-point straightening zone;
Figs. 2 through 5 are schematic views of a low-head CCM
comprising a fifteen-point straightening zone according to the present invention;
Figs. 6 and 7 are views of straightening~-roll assemblies according to the present invention, Fig. 8 is a graph showing a load by one pair of the straightening rolls applied to a strand during straightening in the three successive continuous casting (CC) operations;
and Fig. 9 is a graph showing the S-N curve in a multi--point straightening zone.
In Fig. 1, the low-head CCM produced by Sumitomo Metals Co., Ltd. (TRANS. IRON & STEEL INSTITUTE OF JAPAN
Vol 20. NO. 12.1980 page B-565) and described in Japanese Laid-open Patent Application Nos. 56-14062 through 14065 (1981) is schematically illustrated. The machine height H
of this low-head CCM, which is collec-tively denoted by l, is a little less than 6 m, and in the five-point straight-ening zone 2, 5ix straightening rolls 7 are succcessi~elyarranged in this zone 2 and define curves having succes-sively increasing radii Rl through R5, respectively, Rl is the basic radius of -the curve and is 5800 mm and ~2 is 7100 mm. A curved mold is denoted by I. In such a low-head CCM, low-speed (from 0.7 to 0.85 m/min) and moderate-cooling casting is carried out. Also, in the five-poin-t straighten-ing zone 2 in which six stralghtening rolls 7 are succes-sively arranged, a section of -the strand 3, in which the molten steel has not yet been solidified and the thickness of the high-temperature solidified shell is thin, is sub-jected to straightening at all five straightening polnts Pn (n=l 5), so that the straightening s-train is 0.35~ or less. The percentage of solidificatlon of the molten steel in said section being straightened in the five-point straightening zone 2 is from ~0 to 70%, -the ferrostatic pressure applied to said section is low, and the surface temperature of said section is from 900 to 1000C.
Allegedly, the temperature of the strand is high, and the quality of the strand is not inferior to but instead is improved over that of a strand obtained by means of a high--head CCM.
The low-head CCM illustrated in Fig. l and described above is practlcally operated accordlng to the info.rmation given in the above-mentioned technical report and has a machine height of a little less than 6 m, the basic radius (Rl) of the curve being 5.8 m, and comprises a five-point straightening zone in which six straightening rolls 7 are successively arranged. This low-head CCM is hereinafter referred to as the SH-CCM.
When the applicant's proposed CCM described hereinabove is compared with the SH-CCM, the former is distinct from the latter in respect to the following: (a) high-speed and moderate-cooling casting is carried out in a low-head CCM
in which the machine height and the basic radius of the curve are as small as possible and in which the straigh-ten-ing points are increased; Ib) with a decrease in the machine height and the basic radius of the curve, as well as an increase in -the straightening points, the straighten-ing strain can be better distributed in the strand and therefore can be decreased more; and (c) consequently, the above mentioned (1), (2), and (3) required for realizing the CD process can be reliably and simultaneously achieved.
On the other hand, the SH-CCM is distinct from the applicant's proposed CCM in respect to the following: (a) the SH-CCM is constructed so as to continuously cast steels of a special size or small lots while the continuous casting of mass produced steels is carried out in an existing continuous-casting machine in which the radius (R~ o.~ the curve is 12.5 m; (b) the machine height of -the S~I-CCM is such that it can be installed in a steel-refining mill without the necessity ox creating addi-tional space, the reason for the production of the SH-CC~ being that previ-ously the ingot-making yard and the ladle cranes of the steel-refining mill of the SH-CCM producer were idle due to an increase in the percentage of continuously cast steels;
(c) as a result of (b), the costs of the SH-CCM, including the installation and construction costs are very low;
and (d) strands are charged, as a rule, into a heating furnace in a rolling-mill with a hot charge It is an object of -the present invention to improve the conventional bow-type continuous-casting method and apparatus so that the CD process can be realized.
It is another object of -the present invention to improve the low-head CCM and continuous casting in the low-head CCM so that the above mentioned (l), (2), and (3) can be reliably and simultnaeously achieved.
In accordance with the objects of the present in-vention, there is provided a bow-type continuous-casting lo method, wherein a strand is straightened, at a plurality of straightening points, by means of a plurality of pairs of straightening rolls which are successively arranged in a multi-point straightening zone and which define the radii of the curves, said radii successively increasing in the multi-point straightening zone, characterized in that during a non-stationary casting period in which the top section or bottom section of said strand is conveyed through said multi-point straightening zone, at least one selected pair of said straightening rolls is shun-ted from the defined radius of the curve, thereby increasing the dis-tance between -the pairs of straightening rolls, which pairs exert a straightening effec-t on said strand, and decreasing the straightening points of said multi-point straightening zone. Said distance is hereinafter referred to as the straightening roll pitch.
In accordance with the objects of the present in-vention, there is also provided a bow-type continuous--casting apparatus having a low heigh-t and comprising a multi-point straightening zone in which a plurality of pairs of straightening rolls for straightening a strand are stationarily arranged and define curves having successively increasing radii, characterized in that at least one selected pair of said straightening rolls is operably connected to an elastic means for automatically shunting said at least one selected pair of the straightening rolls from the defined radius of the curve during a non-stationar~
casting period in which the top section or the bottom ~8~
section of said strand is conveyed through said multi-point straightening zone.
In an embodiment of the bow-type continuous-casting method according to the present invention, the basic radius of the curve of -the strand is from 3 to 5 m and the number of straightening points is from five to fifteen. So that the continuous-casting machine of the present inven-tion has a low machine height, the basic radius of the curve of the strand, i.e., the radius of the curved mold, must be small or is preferably 5 m at the maximum. The basic radius of the curve is, however, desirably at least 3 m according to the results of a study of the relationship between the basic radius of the curve, the casting speed, the thickness of the strand, and the technique of pouring molten steel into a curved mold. A basic radius of the curve of -the strand of at least 3 m is deemed to be necessary for eliminating any restrictions on the pouring of the molten steel into a curved mold, which is curved, when a strand having a thickness of 200 mm or more, particularly from 200 to 300 mm, is to be formed at a high casting speed of 1.2 m/min or more, par-ticularly approxima-tely 1.7 m/minute.
When the basic radius of the curve of the strand is 3 m and is formed by means of high-speed and moderate--cooling casting, particularly in a case in which the cas-ting speed is 1.7 m/minute, the section of the strand subjected -to straightening has a surface -temperature of 900C or more and also has a solidiEied shell 60 mm -thick ox less at each side of the s-trand. The number of straightening points for successively straightening said section must be three or more so as to keep the straighten-ing strain below the permissible value at all the straight-ening points.
In the low-head CCM of the present invention, the casting of a strand includes a stationary costing period and a non-stationary casting period. In the stationary casting period, a section of the strand, or the so-called middle section, is conveyed through the multi-point straightening zone in which the straightening rolls are successively arranged, the section having a high temper-ature and a thin solidified shell, containing a consider-able amount of molten metal, and being subjected to a low ferrostatic pressure. A load, hereinafter referred to as the stationary roll load, is applied to each ox the straightening rolls, all of which are successively arranged in the multi-point straightening zone, and the stationary roll load is the sum of the reaction force due to straight-ening PUB (M) and the reaction force due to bulging PB (M)(P B (M)~PB (M)). In a non-stationary casting period, a section of the strand, or the so-called top or bottom section, in which virtually complete solidification of the molten metal is achieved, is subjected to multi point straightening in a multi-point straightening zone in which the straightening rolls are successively arranged. Since the reaction force duo to bulging during a non-stationary casting period is very low, the load applied to the top or bottom section, hereinafter referred to as the non-stationary roll load, essentially consists of the reaction force due to straightening PUB (T) or Put (B).
The present inventors tenta-~ively calculated the stationary and non-stationary roll loads in a low-head CCM
under conditions in which: the basic radius oE -the curve of the strand was from 3 to 5 m; -the number of straigh-ten-ing points in the multi-point s-traightening zone in which the straightening rolls are successively arranged was from 5 to 15; the cross section of the strand was from 200 to 300 mm in thickness and approximately 2000 mm in width;
and high-speed and moderate-coollng casting was carried out. The stationary roll load was from 30 to 45 tons (the reaction force due to bulging was from 10 to 15 tons and the reaction force due to straightening was from 20 -to 30 tons). The non-stationary roll load was from 200 to 240 tons, being from five to seven times as grea-t as the stationary roll load. Contrary to this, in the conven-tional bow-type CCM, the non-stationary roll load is only approximately three times as great as the stationary roll load. Namely, when low-speed and strong-cooling casting is carried out in the conventional bow-type CCM in which the basic radius (Rl) of the curve is 10.5 m, the stationary and non-stationary roll loads applied to a 200-300 mm thick and approximately 2000 mm wide strand during its conveyance through a single-point straightening zone are from 60 to 70 -tons and from 200 to 240 tons, respectively.
Accordingly, in the low-head CCM that the s-traightening lo rolls of the multi-point straightening zone, which rolls are successively arranged, must -tolerate a considerably high load during the non-stationary period, which period is a vexy minor par-t of the entire casting period.
before completing the present invention, the inven-tors lS considered whether or not it would be possible for a multi -point straightening zone, in which the straightening rolls are successively arranged, particularly comprising from five to fifteen straightening points to have a s-traightening roll pitch enabling the bulging strain to be satisfactorily ~0 suppressed and a roll diameter capable of tolerating the non-stationary roll load. This was found to be possible but is not reliable enough to realize the CD process. More specifically, when straightening in a multi-point straight-ening zone in which the straightening rolls are successively arranged is carried out, the straightening rolls are peri-odically subjected to stationary and non-stationary roll loads, the non-sta-tionary roll load being from five to seven times as great as the stationary roll load. As a result of the difference in loads, the life of the straightening rolls is shortened, and therefore the straightening rolls must be replaced frequently. In addition, since the number of straightening points is large, the CD process cannot be reliably realized.
A multi-point straightening zone in which a plurality of straightening rolls are successively arranged must simul-taneously satisfy -two requirements which are contradictory.
One of the requirements is tha-t the straightening rolls be - 10 - Il.
unlikely to undergo destruction. The other requlrement is that the straightening rolls be reliable. When the number of straightening points is small, the number of repeated applications of permissible stress (I ), shown in the ordinate of Fig. 8, is small, which number is represented in the abscissa of Fig. 9 by "Na". The de-structio~ stress at which a material undergoes des-truction after a given number (Na) of repeated applications of permissible stress (pa) is determined by the well-known S-N
curve or Wohler curve. Therefore, when stress applied to the straightening rolls is low, the permissible number of repeated application of stress, which number is permissible in the light of life of the straightening rolls, is great.
In addition, when the number of straightening points is small, the permissible stress (pa) is high. Contrary to this, in a multi~point straightening zone in which the straightening rolls are successively arranged, a reduction in the number of straightening points leads to an increase in the amplitude of s-tress (a), shown in the ordina-te of Fig. 8, with the result that the difference in the station-ary and nonstationary roll loads is dras-tically increased this in turn leads to a reduction in the reliabili-ty of the straightening rolls. Accordingly, the number of straight-ening points which can makes possible fulfillment of one of the above-mentioned requirements does not maze possLble fulfillment of the other requirement, These two require-ments can be fulfilled in accordance with a concept of the resent in~ntion in which the middle section and the -top or bo-ttom section of a strand are straigh-tened at different straightening strainsj the straightening strain of the middle section being such that specifically the quality of the strand is ensured, and in which the straightening strain in the top or bottom section may be higher than the permissible value in the light of the quality ox the strand since a part of the top or bottom section becomes a crop, and the reliability of the low-head CCM is specifically ensured and enhanced by decreasing the non-stationary roll 328~
load The present inventors discovered that the shunting of at least one pair of straightening rolls hereinafter simply referred to as the shunting method, can increase the straightening strain and can decrease the non-stationary roll load, thereby increasing the number of repeated appli-cation of a permissible stress (I ) applied to the straight-ening rolls. Since the non-stationary roll load can be decreased by means of the shunting method and, further, since the number of straightening points in the multi-point straightening zone of the present invention is large, the reliability of the bow-type CCM according to the present invention is enhanced.
In an embodiment of the shunt ng method according to the present inven-tion, said at least one selected pair of straightening rolls shunted from the defined radius of -the curve is either an even or an uneven numbered pair of straightenlng rolls as seen in the withdrawal direction of the strand. In this embodiment, the straightening roll pitch and the non-stationary roll load can be decreased by approximately one half.
In another embodiment of the shunting method accordiny to the present invention, a plurality of pairs of straight-ening rolls comprises a plurality of groups, each group comprising at least three pairs of straightening rolls, and said at least one selected pair of straigh-tening rolls LS
either the second or a subsequent pair of straightening rolls of said groups as seen in -the withdrawal direction of the strand. In this embodiment, the straightening roll pitch in each group and the non-stationary roll load can be decreased approximately hi times, wherein n indicates the number of pairs straightening rolls shunted in each group.
In Fig. 2, an embodiment of a low-head CC~ according to the present invention is schematically illustrated.
Namely, the multi-point straightening zone 10 comprises sixteen pairs ox straightening rolls 11 sucessively arranged.
The radii of the curves Rn defined by the sixteen pairs of ... . . . .. _ . . .. . . _ . .... .. _ . .. . _ .. , .. . .. . .. . .. .. .. . . . _ .. . .
straightening rolls 11 successively increase from Rl to R16=~ in the withdrawal direction of the strand 3. Since the radius Rl is the basic radius of the curve defined by the curved Mold, the number of straightening points is fifteen. Thy machine height H is preferably from 3.4 to 5.2 m, and the basic radius Rl of the curve defined by the curved mold is from 3 to 5 m. When a top or bottom section (not shown) having a length of from 500 to 1000 mm from either of the ends of the strand and a low temperature due to virtually complete solidification of the molten metal is conveyed through the multi-point straightening zone 10, the even numbered pairs of straightening rolls defining the 2' 4' R6~ Rg, R1o~ R12~ R14~ and R16 are shunted from the defined radii so that the straightening roll pitch is approximately doubled. The length of the sectlon of a strand being unbent between adjacent pairs of straightening rolls is also approximately doubled. This length is herein-after referred to as the unbendiny-arm length.
In Fig. 3, when a top or bottom section (not shown) having a length of from 500 to 1000 mm from either of the ends of the strand 3 and having a low temperature due to virtually complete solidification of the molten metal is conveyed through the multi-poin-t straightening zone 10, the uneven numbered pairs of straightening rolls defininy the 1 2 3' R5~ R7, R9, Rll, R13~ and R15 ore shunted straightening rolls and the bending-arm length is appro-ximately doubled.
In Fig. 4, an embodiment of the shunting method, which embodiment is appropriate for a low-head CCM having a machine height of, for example, 3 m, is schematically illustrated. In this embodiment, every three pairs of straightening rolls 11 as calculated in the withdrawal direction of the strand constitute one group, and therefore the multi-point straightening zone 10 has five groups of straightening rolls, the three pairs of straightening rolls 11 in each group being successively arranged. The second and third pairs of straightening rolls 11 in the .. . . .. . . . . . .
)2~
five groups are shunted from the defined radii R2, R3, R5, 6' B' 9' 11' R12' Rl4, and R15 In this embodiment, the basic radius Rl of the curve may be 3 m, and the straightening roll pitch and the unbending-arm length are approximately tripled.
In Fig. 5, an embodiment of the shunting method, which embodiment is appropriate for a low-head CCM having a height of, for example, 3 m, is schematically illustrated In this embodiment, every four pairs of s-traightening rolls ll as calculated in -the withdrawal direction of the strand constitute one group, and therefore the multi-point straightening zone 10 has four groups, the four pairs of straightening rolls 11 each in group being successively arranged. The second, third, and fourth pairs of straight-ening rolls 11 in the four groups are shunted from the defined radii R2, R3~ R4~ R6~ R7~ R~ Rio Rll~ R12' 14 R15, and Rl6 (=~). In this embodiment, the basic radius R
of the curve may be 3 m, and the straightening roll pitch and the unbending-arm length are approximately quadrupled.
As stated above, shunting is carried out during a period when the top or bottom section of a strand, where virtualy complete solidification of the molten metal is attained, is conveyed through a multi-point straightening zone in which the straightening rolls are successively ~5 arranged. Shunting during this period is achieved by of tracking a section of the strand being conveyecl through the multi-point straightening 20ne men-tioned above and then, upon detecting the border between the middle section and the top or bottom section of the strand, successively shunting pairs of the straightening rolls as seen in the withdrawal direction of the strand.
In Fig. 6, s-traightening-roll assemblies which are capable of realizing the shunting`method are illustrated.
The two straightening-roll assemblies at either the inner or outer side of the strand are shown while the two straightening-roll assemblies at the other side of the strand are not shown. One straightening-roll assembly, which is not shunted during a non-stationary casting period, is collectively denoted by lls while the other straightening--roll assembly, which is shunted during a non-stationary casting period, is collectively denoted by llm. The stxaightening-roll assembly lls is hereinafter referred to as the stationary s-traightening-roll assembly lls. The straightening roll 11 of the stationary straightening-roll assembly lls is mounted on a bearing box 16 which is rigidly secured to a supporting frame 17. The supporting frame 17 is rigidly secured by means of bolts and muts 18 to the -top surface of a supporting base 15, which is in turn secured to a stationary frame 14 of a low-head CCM by means of bolts and nuts 13. Therefore, the stationary straightening--roll assembly lls is stationarily arranged in the multi--point straightening zone during both the stationary and nonstationary casting periods.
In the straightening-roll assembly llmj hereinafter referred to as the movable straightening-roll assembly llm, it is now described how one s-traightening roll in each pair of straightening rolls is automatically moved so as to decrease the number of straightening rolls. Generally speaking, the movable straightening-roll assembly llm comprises an elastic means which is operably connected to the straightening roll 11 so that the straigh-tening roll 11 rotatably engages with the s-trand (no-t shown) and which ls responsive to the sta-tionary and non-stationary roll loads as a rigid body and an elastic body, respectively. The elastic means preferably comprises cone-shaped springs 28 or a hydraulic cylinder (not shown). The cone-shaped springs 28 are secured between the supporting frame 17 and the supporting base 15. The supporting frame 17 is pre ferably slidably mounted on the supporting base 15 so that the supporting frame 17 is slidabI~ retracted towards a space 24 within the supporting base 15 during a non--stationary casting period. To accomplish this slidable retraction, the supporting base 15 has a large-diameter base part 20, which defines the space 24 thexein, and a ... . . .. ... .... . .. . . . . . . .
medium-diameter cylindrical part 21, which defines a ver-tical slot 23 therein. In addition, the supporting frame 17 has a frame 25 for supporting the bearing box 16 and a flange 26, which comprises a downwardly protruding S xod 27. The downwardly protrudins rod 27 is inserted in and is vertically slidable along the vertical slot 23.
The cone-shaped springs 28 are preferably surrounded by the inner wall of a cylindrical sleeve 29 whlch is secured to the flange 26 but which is slidably displaced along the outer periphery of the medium-diameter cylindrical part 21 until the cylindrical sleeve 29 engages with the top surface of the large-diameter base part 20. The length ox the cylind.rical sleeve 29 is de-termined so that -the maximum stroke during slidable retraction of the supporting frame 17 is restristed by the distance between the top surface of the medium-diameter cylindrical part 21 and the lower end of the cylindrical sleeve 29 during the stationary casting period.
Due to the spring action of the cone-shaped springs 28, the supporting frame 17 is capable of slidably retract-ing due to the force of the strand (not shown) during a non-stationary casting period. A slidable advancing of the supporting frame 17 is preferably restricted by stopper disc 30 which is secured to the lower end of the rod 27 by means of a bolt 31 and which can enyage with the lower end of the medium-diameter cylindrical part 21. 'L'he ver-tical position of the supporting frame 17 rela-tlve -to the sup porting base 15 can therefore be maintained within a predetermined range due to the cylindrical sleeve 29 and the stopper disc 30, the stopper disc 30 preventing the suppor-ting frame 17 from moving away from the supporting base 15.
The straightening roll 11 of the movable straightening--roll assembly llm can be automatically retracted or dis-placed in a downward direction, as shown in the drawing;when the strand (not shown) exerts on said roll a critical force which is greater than the value predetermined by the ... . .. . . . . . .. . . .. .. ... . . . ... ... . .. . ... ..... .. . . . ..
cone-shaped springs 28. This critical force is one half of the non-stationary roll load due to shunting of at least one selected pair of straightening rolls.
Shunting is now described in regard to how the radius of the curve defined by one pair of straightening rolls varies.
Although in the following description shunting of only one pair of straightening rolls is described, it is evident that shunting of a plurality of pairs of straightening rolls can be carried out accordingly. In the above-mentioned pair of straightening rolls, the straightening roll located on the inner side of a strand is retracted or displaced toward the interior of the strand or in an upward direction during shunting. In addition to or instead of this dis-placement or retraction, the corresponding straighteningroll located on the outer side of the strand is clisplaced toward the exterior of the strand or in a downward direction during shunting. l'hese two straightening roils are herein-after simply referred -to as the inner roll and the outer roll, respectively. The inner roll displaced as described above tends to decrease the radius of the curve of the strand as compared with the radius (Rn) ox the curve defined by the pair of straightening rolls before shunting or during the stationary casting period. This raclius is simply referred to as the theoretical radius (Rn). The outer roll displaced as described above tends to increase regarding the radius of the curve of the strand as compared with the theoretical radius (Rn).
When the inner and outer rolls are connectecl to the two hydraulic cylinders, respectively, a decrease in the radius of the curve and an increase in the radius of the curve as compared with the theoretical radius (Rn) simul-taneously result so that the inner and outer rolls can nolonger exert a straightening force on a strand or engage in the straightening or a strand. On the other hand, when the inner and outer rolls are operably connected to two cone--shaped springs, respectively, either a decrease in the 2~
radius of the curve defined by the inner roll or an increase in the radius of the curve defined by the outer roll results so that either the inner roll or the outer roll can essen-tially no longer engage ln the straightening of the strand.
I. Shunting in which the elastic means is a cone--shaped spring and in which an increase in the radius of the curve defined by the outer roll takes place is now described. In this -type of shunting, the first and third pairs of rolls are not shunted but the second pair of rolls is shunted during a non-stationary casting period.
A. Conveyance of the Top Section of a Strand Through the Multi-point Straightening Zone en the top end of a strand arrives at the second pair of inner and outer rolls, the top section is between the second and third pairs of rolls. The outer roll of the second pair of rolls is retracted and is sub-jected to a load which is determined by the cone-shaped spring operably connec-ted to the ou-ter roll. The outer roll presumably still engages in the straightening of the strand since the outer roll exerts on the strand a force which is determined by the cone-shaped spring and which is less than the straiyhtening force during the stationary casting period. However, since the degree of engagement of the outer roll in straightening is very small as compared with that of the inner roll, straightening is carried out essentially by the inner roll of -the second palr of rolls.
on increase in the straightening roll pi-tch and in the unbending-a.rm lengkh therefore results since the pairs of rolls whlch engage in the straightening of the strand, i.e., the inner and outer rolls, are the first and third pairs of rollsO
B. Conveyance of the Bottom Section of a Strand Through the Multi-Point Straightening Zone When the bottom section of a strand arrives at the second pair of inner and outer rolls, the bottom end of the strand is between the first and second pairs of rolls. The outer roll of the second pair of rolls is 8~
retracted and is subjected to a load which is determined by the cone-shaped spring operably connected to the outer roll. An increase in the straighteniny roll pitch and in the unbending-arm length results since, as in A above, the outer roll exerts on the strand a force which is determined by the cone-shaped spring and which is less than the straightening force during the stationary casting period.
II. Shunting in which the elastic means is a hydraulic cylinder and in which the first and third pairs of rolls are not shunted but the second pair of rolls is shunted during a non-stationary casting period is now described.
A. Conveyance of the Top Section of a Strand When the border between the top and middle sections of a strand is detected by means of tracking as having arrived at the first pair of rolls, both the inner and outer rolls of the second pair of rolls are retracted.
After the top end of the strand has passed through the second pair of rolls, the inner and outer rolls of the second pair of rolls are reverted to their original positions. As a result of retraction, the force to which the inner and outer rolls of the second pair of rolls are subjected during a non-stationary casting period is the stationary roll load. In addition, the force to which the non--shunted first and third pairs of rolls are subjec-ted during a non-stationary casting period is only approximately one half the non-stationary roll load according to the conventlonal straightening process.
An increase in the straightening roll pitch and in the unbending-arm length results due to both a decrease in and an increase in the radii of the curves defined by the inner and outer rolls, respectively.
B. Conveyance ox the bottom Section of a Strand When the bottom end of a strand is deter-mined by means of tracking as having arrived at the firs-t pair of rolls, the inner and outer rolls of the second pair of rolls are retracted. When the border between the bo-ttom and middle sections is detected by means of tracking as _ _ . _ _ _ _ _ . .. _ . _ _ _ _ _ _ .. _ . . .... . ... . .. . .. . .. . . .. . . . . .
having arrived at the third pair of rolls, the inner and t;
outer rolls of the second pair of rolls are reverted to their original positions. As a result of retraction, the force to which the second pair of rolls is subjected during a non-stationary casting period is the stationary roll load. In addition, the force to which the non-shunted first and third paixs of rolls are subjected during a non-stationary casting period is only approximately one halE the non-stationary roll load according to the con-ventional straightening process. An increase in thestraightening roll pitch and in the unbending-arm length results due to, as in A above, both a decrease in and an increase in the radii of the curves defined by the inner and outer rolls, respectively.
In the above description of the two types of shunting, it is presumed that both the top and bottom sections are longer than the straightening roll pitch.
Bow-type continuous casting methods according -to the present invention and a conventional method are now des-cried with reference to the example and the comparativeexample.
Example The essential parts of the low-head CCM of the example according to the present invention are schematically shown in Fig. 2. The continuous casting method ox the present invention was carried out by means of a low-head CCM under the casting parameters given below. The parameters of the low-head CCM were as follows:
A. Basic radius (Rl) ox the curve: 3 m B. Multi-point straightening zone lO:
(1) Straightening points: 15 (2) Radii of pairs of stationary straightening rolls ll:
.. .. .. .. . ..
1~1 R2 : 3100 mm !
R4 : 3650 mm R6 : 4400 mm R8 : 5500 mm Rlo: 7500 mm R12: 11650 mm R14: 26000 mm
rolls is decreased, an increase in the bulging strain can be prevented. However, such a method for preventing an increase in the bulging strain cannot be employed in the case of the high-head CCM because it is difficult to support by means of small-diameter rolls a strand to which a hiyh ferrostatic pressure due to a high machine height is applied.
In an attempt to reduce the ferros-tatic pressure, such a high machine height as that provided in the conventional bow-type CCM is reduced by one half or less than one half and simultaneously the conventional radius of the curve is decreased by, for example, one half or less than one half, according to the applicant's proposals. In this case, thy unbending of a strand is carried out at a plurality of straightening points since, if conventional single-point straightening were carried out in the case of a s-trand having a small radius, the straightening strain, which can cause inner defects in the strand, would be increased and thus inner defects would frequently occur. In other words, concentration of the straightening strain on one point of the strand is avoided and instead the straightening strain is distributed to a plurality of straightening points in the strand where the straightening strain is made lower than the permissible value.
Z5 In addition to the present applicant, Sumitomo Metals Co., Ltd. has recently proposed a low-head CC~ in which strands having a high material quality can be efficiently produced due to a low machine height.
The prior art is now described with reference to Fig. 1.
In the drawings:
Figure 1 is a schematic vie of a known low-head CCM
comprising a five-point straightening zone;
Figs. 2 through 5 are schematic views of a low-head CCM
comprising a fifteen-point straightening zone according to the present invention;
Figs. 6 and 7 are views of straightening~-roll assemblies according to the present invention, Fig. 8 is a graph showing a load by one pair of the straightening rolls applied to a strand during straightening in the three successive continuous casting (CC) operations;
and Fig. 9 is a graph showing the S-N curve in a multi--point straightening zone.
In Fig. 1, the low-head CCM produced by Sumitomo Metals Co., Ltd. (TRANS. IRON & STEEL INSTITUTE OF JAPAN
Vol 20. NO. 12.1980 page B-565) and described in Japanese Laid-open Patent Application Nos. 56-14062 through 14065 (1981) is schematically illustrated. The machine height H
of this low-head CCM, which is collec-tively denoted by l, is a little less than 6 m, and in the five-point straight-ening zone 2, 5ix straightening rolls 7 are succcessi~elyarranged in this zone 2 and define curves having succes-sively increasing radii Rl through R5, respectively, Rl is the basic radius of -the curve and is 5800 mm and ~2 is 7100 mm. A curved mold is denoted by I. In such a low-head CCM, low-speed (from 0.7 to 0.85 m/min) and moderate-cooling casting is carried out. Also, in the five-poin-t straighten-ing zone 2 in which six stralghtening rolls 7 are succes-sively arranged, a section of -the strand 3, in which the molten steel has not yet been solidified and the thickness of the high-temperature solidified shell is thin, is sub-jected to straightening at all five straightening polnts Pn (n=l 5), so that the straightening s-train is 0.35~ or less. The percentage of solidificatlon of the molten steel in said section being straightened in the five-point straightening zone 2 is from ~0 to 70%, -the ferrostatic pressure applied to said section is low, and the surface temperature of said section is from 900 to 1000C.
Allegedly, the temperature of the strand is high, and the quality of the strand is not inferior to but instead is improved over that of a strand obtained by means of a high--head CCM.
The low-head CCM illustrated in Fig. l and described above is practlcally operated accordlng to the info.rmation given in the above-mentioned technical report and has a machine height of a little less than 6 m, the basic radius (Rl) of the curve being 5.8 m, and comprises a five-point straightening zone in which six straightening rolls 7 are successively arranged. This low-head CCM is hereinafter referred to as the SH-CCM.
When the applicant's proposed CCM described hereinabove is compared with the SH-CCM, the former is distinct from the latter in respect to the following: (a) high-speed and moderate-cooling casting is carried out in a low-head CCM
in which the machine height and the basic radius of the curve are as small as possible and in which the straigh-ten-ing points are increased; Ib) with a decrease in the machine height and the basic radius of the curve, as well as an increase in -the straightening points, the straighten-ing strain can be better distributed in the strand and therefore can be decreased more; and (c) consequently, the above mentioned (1), (2), and (3) required for realizing the CD process can be reliably and simultaneously achieved.
On the other hand, the SH-CCM is distinct from the applicant's proposed CCM in respect to the following: (a) the SH-CCM is constructed so as to continuously cast steels of a special size or small lots while the continuous casting of mass produced steels is carried out in an existing continuous-casting machine in which the radius (R~ o.~ the curve is 12.5 m; (b) the machine height of -the S~I-CCM is such that it can be installed in a steel-refining mill without the necessity ox creating addi-tional space, the reason for the production of the SH-CC~ being that previ-ously the ingot-making yard and the ladle cranes of the steel-refining mill of the SH-CCM producer were idle due to an increase in the percentage of continuously cast steels;
(c) as a result of (b), the costs of the SH-CCM, including the installation and construction costs are very low;
and (d) strands are charged, as a rule, into a heating furnace in a rolling-mill with a hot charge It is an object of -the present invention to improve the conventional bow-type continuous-casting method and apparatus so that the CD process can be realized.
It is another object of -the present invention to improve the low-head CCM and continuous casting in the low-head CCM so that the above mentioned (l), (2), and (3) can be reliably and simultnaeously achieved.
In accordance with the objects of the present in-vention, there is provided a bow-type continuous-casting lo method, wherein a strand is straightened, at a plurality of straightening points, by means of a plurality of pairs of straightening rolls which are successively arranged in a multi-point straightening zone and which define the radii of the curves, said radii successively increasing in the multi-point straightening zone, characterized in that during a non-stationary casting period in which the top section or bottom section of said strand is conveyed through said multi-point straightening zone, at least one selected pair of said straightening rolls is shun-ted from the defined radius of the curve, thereby increasing the dis-tance between -the pairs of straightening rolls, which pairs exert a straightening effec-t on said strand, and decreasing the straightening points of said multi-point straightening zone. Said distance is hereinafter referred to as the straightening roll pitch.
In accordance with the objects of the present in-vention, there is also provided a bow-type continuous--casting apparatus having a low heigh-t and comprising a multi-point straightening zone in which a plurality of pairs of straightening rolls for straightening a strand are stationarily arranged and define curves having successively increasing radii, characterized in that at least one selected pair of said straightening rolls is operably connected to an elastic means for automatically shunting said at least one selected pair of the straightening rolls from the defined radius of the curve during a non-stationar~
casting period in which the top section or the bottom ~8~
section of said strand is conveyed through said multi-point straightening zone.
In an embodiment of the bow-type continuous-casting method according to the present invention, the basic radius of the curve of -the strand is from 3 to 5 m and the number of straightening points is from five to fifteen. So that the continuous-casting machine of the present inven-tion has a low machine height, the basic radius of the curve of the strand, i.e., the radius of the curved mold, must be small or is preferably 5 m at the maximum. The basic radius of the curve is, however, desirably at least 3 m according to the results of a study of the relationship between the basic radius of the curve, the casting speed, the thickness of the strand, and the technique of pouring molten steel into a curved mold. A basic radius of the curve of -the strand of at least 3 m is deemed to be necessary for eliminating any restrictions on the pouring of the molten steel into a curved mold, which is curved, when a strand having a thickness of 200 mm or more, particularly from 200 to 300 mm, is to be formed at a high casting speed of 1.2 m/min or more, par-ticularly approxima-tely 1.7 m/minute.
When the basic radius of the curve of the strand is 3 m and is formed by means of high-speed and moderate--cooling casting, particularly in a case in which the cas-ting speed is 1.7 m/minute, the section of the strand subjected -to straightening has a surface -temperature of 900C or more and also has a solidiEied shell 60 mm -thick ox less at each side of the s-trand. The number of straightening points for successively straightening said section must be three or more so as to keep the straighten-ing strain below the permissible value at all the straight-ening points.
In the low-head CCM of the present invention, the casting of a strand includes a stationary costing period and a non-stationary casting period. In the stationary casting period, a section of the strand, or the so-called middle section, is conveyed through the multi-point straightening zone in which the straightening rolls are successively arranged, the section having a high temper-ature and a thin solidified shell, containing a consider-able amount of molten metal, and being subjected to a low ferrostatic pressure. A load, hereinafter referred to as the stationary roll load, is applied to each ox the straightening rolls, all of which are successively arranged in the multi-point straightening zone, and the stationary roll load is the sum of the reaction force due to straight-ening PUB (M) and the reaction force due to bulging PB (M)(P B (M)~PB (M)). In a non-stationary casting period, a section of the strand, or the so-called top or bottom section, in which virtually complete solidification of the molten metal is achieved, is subjected to multi point straightening in a multi-point straightening zone in which the straightening rolls are successively arranged. Since the reaction force duo to bulging during a non-stationary casting period is very low, the load applied to the top or bottom section, hereinafter referred to as the non-stationary roll load, essentially consists of the reaction force due to straightening PUB (T) or Put (B).
The present inventors tenta-~ively calculated the stationary and non-stationary roll loads in a low-head CCM
under conditions in which: the basic radius oE -the curve of the strand was from 3 to 5 m; -the number of straigh-ten-ing points in the multi-point s-traightening zone in which the straightening rolls are successively arranged was from 5 to 15; the cross section of the strand was from 200 to 300 mm in thickness and approximately 2000 mm in width;
and high-speed and moderate-coollng casting was carried out. The stationary roll load was from 30 to 45 tons (the reaction force due to bulging was from 10 to 15 tons and the reaction force due to straightening was from 20 -to 30 tons). The non-stationary roll load was from 200 to 240 tons, being from five to seven times as grea-t as the stationary roll load. Contrary to this, in the conven-tional bow-type CCM, the non-stationary roll load is only approximately three times as great as the stationary roll load. Namely, when low-speed and strong-cooling casting is carried out in the conventional bow-type CCM in which the basic radius (Rl) of the curve is 10.5 m, the stationary and non-stationary roll loads applied to a 200-300 mm thick and approximately 2000 mm wide strand during its conveyance through a single-point straightening zone are from 60 to 70 -tons and from 200 to 240 tons, respectively.
Accordingly, in the low-head CCM that the s-traightening lo rolls of the multi-point straightening zone, which rolls are successively arranged, must -tolerate a considerably high load during the non-stationary period, which period is a vexy minor par-t of the entire casting period.
before completing the present invention, the inven-tors lS considered whether or not it would be possible for a multi -point straightening zone, in which the straightening rolls are successively arranged, particularly comprising from five to fifteen straightening points to have a s-traightening roll pitch enabling the bulging strain to be satisfactorily ~0 suppressed and a roll diameter capable of tolerating the non-stationary roll load. This was found to be possible but is not reliable enough to realize the CD process. More specifically, when straightening in a multi-point straight-ening zone in which the straightening rolls are successively arranged is carried out, the straightening rolls are peri-odically subjected to stationary and non-stationary roll loads, the non-sta-tionary roll load being from five to seven times as great as the stationary roll load. As a result of the difference in loads, the life of the straightening rolls is shortened, and therefore the straightening rolls must be replaced frequently. In addition, since the number of straightening points is large, the CD process cannot be reliably realized.
A multi-point straightening zone in which a plurality of straightening rolls are successively arranged must simul-taneously satisfy -two requirements which are contradictory.
One of the requirements is tha-t the straightening rolls be - 10 - Il.
unlikely to undergo destruction. The other requlrement is that the straightening rolls be reliable. When the number of straightening points is small, the number of repeated applications of permissible stress (I ), shown in the ordinate of Fig. 8, is small, which number is represented in the abscissa of Fig. 9 by "Na". The de-structio~ stress at which a material undergoes des-truction after a given number (Na) of repeated applications of permissible stress (pa) is determined by the well-known S-N
curve or Wohler curve. Therefore, when stress applied to the straightening rolls is low, the permissible number of repeated application of stress, which number is permissible in the light of life of the straightening rolls, is great.
In addition, when the number of straightening points is small, the permissible stress (pa) is high. Contrary to this, in a multi~point straightening zone in which the straightening rolls are successively arranged, a reduction in the number of straightening points leads to an increase in the amplitude of s-tress (a), shown in the ordina-te of Fig. 8, with the result that the difference in the station-ary and nonstationary roll loads is dras-tically increased this in turn leads to a reduction in the reliabili-ty of the straightening rolls. Accordingly, the number of straight-ening points which can makes possible fulfillment of one of the above-mentioned requirements does not maze possLble fulfillment of the other requirement, These two require-ments can be fulfilled in accordance with a concept of the resent in~ntion in which the middle section and the -top or bo-ttom section of a strand are straigh-tened at different straightening strainsj the straightening strain of the middle section being such that specifically the quality of the strand is ensured, and in which the straightening strain in the top or bottom section may be higher than the permissible value in the light of the quality ox the strand since a part of the top or bottom section becomes a crop, and the reliability of the low-head CCM is specifically ensured and enhanced by decreasing the non-stationary roll 328~
load The present inventors discovered that the shunting of at least one pair of straightening rolls hereinafter simply referred to as the shunting method, can increase the straightening strain and can decrease the non-stationary roll load, thereby increasing the number of repeated appli-cation of a permissible stress (I ) applied to the straight-ening rolls. Since the non-stationary roll load can be decreased by means of the shunting method and, further, since the number of straightening points in the multi-point straightening zone of the present invention is large, the reliability of the bow-type CCM according to the present invention is enhanced.
In an embodiment of the shunt ng method according to the present inven-tion, said at least one selected pair of straightening rolls shunted from the defined radius of -the curve is either an even or an uneven numbered pair of straightenlng rolls as seen in the withdrawal direction of the strand. In this embodiment, the straightening roll pitch and the non-stationary roll load can be decreased by approximately one half.
In another embodiment of the shunting method accordiny to the present invention, a plurality of pairs of straight-ening rolls comprises a plurality of groups, each group comprising at least three pairs of straightening rolls, and said at least one selected pair of straigh-tening rolls LS
either the second or a subsequent pair of straightening rolls of said groups as seen in -the withdrawal direction of the strand. In this embodiment, the straightening roll pitch in each group and the non-stationary roll load can be decreased approximately hi times, wherein n indicates the number of pairs straightening rolls shunted in each group.
In Fig. 2, an embodiment of a low-head CC~ according to the present invention is schematically illustrated.
Namely, the multi-point straightening zone 10 comprises sixteen pairs ox straightening rolls 11 sucessively arranged.
The radii of the curves Rn defined by the sixteen pairs of ... . . . .. _ . . .. . . _ . .... .. _ . .. . _ .. , .. . .. . .. . .. .. .. . . . _ .. . .
straightening rolls 11 successively increase from Rl to R16=~ in the withdrawal direction of the strand 3. Since the radius Rl is the basic radius of the curve defined by the curved Mold, the number of straightening points is fifteen. Thy machine height H is preferably from 3.4 to 5.2 m, and the basic radius Rl of the curve defined by the curved mold is from 3 to 5 m. When a top or bottom section (not shown) having a length of from 500 to 1000 mm from either of the ends of the strand and a low temperature due to virtually complete solidification of the molten metal is conveyed through the multi-point straightening zone 10, the even numbered pairs of straightening rolls defining the 2' 4' R6~ Rg, R1o~ R12~ R14~ and R16 are shunted from the defined radii so that the straightening roll pitch is approximately doubled. The length of the sectlon of a strand being unbent between adjacent pairs of straightening rolls is also approximately doubled. This length is herein-after referred to as the unbendiny-arm length.
In Fig. 3, when a top or bottom section (not shown) having a length of from 500 to 1000 mm from either of the ends of the strand 3 and having a low temperature due to virtually complete solidification of the molten metal is conveyed through the multi-poin-t straightening zone 10, the uneven numbered pairs of straightening rolls defininy the 1 2 3' R5~ R7, R9, Rll, R13~ and R15 ore shunted straightening rolls and the bending-arm length is appro-ximately doubled.
In Fig. 4, an embodiment of the shunting method, which embodiment is appropriate for a low-head CCM having a machine height of, for example, 3 m, is schematically illustrated. In this embodiment, every three pairs of straightening rolls 11 as calculated in the withdrawal direction of the strand constitute one group, and therefore the multi-point straightening zone 10 has five groups of straightening rolls, the three pairs of straightening rolls 11 in each group being successively arranged. The second and third pairs of straightening rolls 11 in the .. . . .. . . . . . .
)2~
five groups are shunted from the defined radii R2, R3, R5, 6' B' 9' 11' R12' Rl4, and R15 In this embodiment, the basic radius Rl of the curve may be 3 m, and the straightening roll pitch and the unbending-arm length are approximately tripled.
In Fig. 5, an embodiment of the shunting method, which embodiment is appropriate for a low-head CCM having a height of, for example, 3 m, is schematically illustrated In this embodiment, every four pairs of s-traightening rolls ll as calculated in -the withdrawal direction of the strand constitute one group, and therefore the multi-point straightening zone 10 has four groups, the four pairs of straightening rolls 11 each in group being successively arranged. The second, third, and fourth pairs of straight-ening rolls 11 in the four groups are shunted from the defined radii R2, R3~ R4~ R6~ R7~ R~ Rio Rll~ R12' 14 R15, and Rl6 (=~). In this embodiment, the basic radius R
of the curve may be 3 m, and the straightening roll pitch and the unbending-arm length are approximately quadrupled.
As stated above, shunting is carried out during a period when the top or bottom section of a strand, where virtualy complete solidification of the molten metal is attained, is conveyed through a multi-point straightening zone in which the straightening rolls are successively ~5 arranged. Shunting during this period is achieved by of tracking a section of the strand being conveyecl through the multi-point straightening 20ne men-tioned above and then, upon detecting the border between the middle section and the top or bottom section of the strand, successively shunting pairs of the straightening rolls as seen in the withdrawal direction of the strand.
In Fig. 6, s-traightening-roll assemblies which are capable of realizing the shunting`method are illustrated.
The two straightening-roll assemblies at either the inner or outer side of the strand are shown while the two straightening-roll assemblies at the other side of the strand are not shown. One straightening-roll assembly, which is not shunted during a non-stationary casting period, is collectively denoted by lls while the other straightening--roll assembly, which is shunted during a non-stationary casting period, is collectively denoted by llm. The stxaightening-roll assembly lls is hereinafter referred to as the stationary s-traightening-roll assembly lls. The straightening roll 11 of the stationary straightening-roll assembly lls is mounted on a bearing box 16 which is rigidly secured to a supporting frame 17. The supporting frame 17 is rigidly secured by means of bolts and muts 18 to the -top surface of a supporting base 15, which is in turn secured to a stationary frame 14 of a low-head CCM by means of bolts and nuts 13. Therefore, the stationary straightening--roll assembly lls is stationarily arranged in the multi--point straightening zone during both the stationary and nonstationary casting periods.
In the straightening-roll assembly llmj hereinafter referred to as the movable straightening-roll assembly llm, it is now described how one s-traightening roll in each pair of straightening rolls is automatically moved so as to decrease the number of straightening rolls. Generally speaking, the movable straightening-roll assembly llm comprises an elastic means which is operably connected to the straightening roll 11 so that the straigh-tening roll 11 rotatably engages with the s-trand (no-t shown) and which ls responsive to the sta-tionary and non-stationary roll loads as a rigid body and an elastic body, respectively. The elastic means preferably comprises cone-shaped springs 28 or a hydraulic cylinder (not shown). The cone-shaped springs 28 are secured between the supporting frame 17 and the supporting base 15. The supporting frame 17 is pre ferably slidably mounted on the supporting base 15 so that the supporting frame 17 is slidabI~ retracted towards a space 24 within the supporting base 15 during a non--stationary casting period. To accomplish this slidable retraction, the supporting base 15 has a large-diameter base part 20, which defines the space 24 thexein, and a ... . . .. ... .... . .. . . . . . . .
medium-diameter cylindrical part 21, which defines a ver-tical slot 23 therein. In addition, the supporting frame 17 has a frame 25 for supporting the bearing box 16 and a flange 26, which comprises a downwardly protruding S xod 27. The downwardly protrudins rod 27 is inserted in and is vertically slidable along the vertical slot 23.
The cone-shaped springs 28 are preferably surrounded by the inner wall of a cylindrical sleeve 29 whlch is secured to the flange 26 but which is slidably displaced along the outer periphery of the medium-diameter cylindrical part 21 until the cylindrical sleeve 29 engages with the top surface of the large-diameter base part 20. The length ox the cylind.rical sleeve 29 is de-termined so that -the maximum stroke during slidable retraction of the supporting frame 17 is restristed by the distance between the top surface of the medium-diameter cylindrical part 21 and the lower end of the cylindrical sleeve 29 during the stationary casting period.
Due to the spring action of the cone-shaped springs 28, the supporting frame 17 is capable of slidably retract-ing due to the force of the strand (not shown) during a non-stationary casting period. A slidable advancing of the supporting frame 17 is preferably restricted by stopper disc 30 which is secured to the lower end of the rod 27 by means of a bolt 31 and which can enyage with the lower end of the medium-diameter cylindrical part 21. 'L'he ver-tical position of the supporting frame 17 rela-tlve -to the sup porting base 15 can therefore be maintained within a predetermined range due to the cylindrical sleeve 29 and the stopper disc 30, the stopper disc 30 preventing the suppor-ting frame 17 from moving away from the supporting base 15.
The straightening roll 11 of the movable straightening--roll assembly llm can be automatically retracted or dis-placed in a downward direction, as shown in the drawing;when the strand (not shown) exerts on said roll a critical force which is greater than the value predetermined by the ... . .. . . . . . .. . . .. .. ... . . . ... ... . .. . ... ..... .. . . . ..
cone-shaped springs 28. This critical force is one half of the non-stationary roll load due to shunting of at least one selected pair of straightening rolls.
Shunting is now described in regard to how the radius of the curve defined by one pair of straightening rolls varies.
Although in the following description shunting of only one pair of straightening rolls is described, it is evident that shunting of a plurality of pairs of straightening rolls can be carried out accordingly. In the above-mentioned pair of straightening rolls, the straightening roll located on the inner side of a strand is retracted or displaced toward the interior of the strand or in an upward direction during shunting. In addition to or instead of this dis-placement or retraction, the corresponding straighteningroll located on the outer side of the strand is clisplaced toward the exterior of the strand or in a downward direction during shunting. l'hese two straightening roils are herein-after simply referred -to as the inner roll and the outer roll, respectively. The inner roll displaced as described above tends to decrease the radius of the curve of the strand as compared with the radius (Rn) ox the curve defined by the pair of straightening rolls before shunting or during the stationary casting period. This raclius is simply referred to as the theoretical radius (Rn). The outer roll displaced as described above tends to increase regarding the radius of the curve of the strand as compared with the theoretical radius (Rn).
When the inner and outer rolls are connectecl to the two hydraulic cylinders, respectively, a decrease in the radius of the curve and an increase in the radius of the curve as compared with the theoretical radius (Rn) simul-taneously result so that the inner and outer rolls can nolonger exert a straightening force on a strand or engage in the straightening or a strand. On the other hand, when the inner and outer rolls are operably connected to two cone--shaped springs, respectively, either a decrease in the 2~
radius of the curve defined by the inner roll or an increase in the radius of the curve defined by the outer roll results so that either the inner roll or the outer roll can essen-tially no longer engage ln the straightening of the strand.
I. Shunting in which the elastic means is a cone--shaped spring and in which an increase in the radius of the curve defined by the outer roll takes place is now described. In this -type of shunting, the first and third pairs of rolls are not shunted but the second pair of rolls is shunted during a non-stationary casting period.
A. Conveyance of the Top Section of a Strand Through the Multi-point Straightening Zone en the top end of a strand arrives at the second pair of inner and outer rolls, the top section is between the second and third pairs of rolls. The outer roll of the second pair of rolls is retracted and is sub-jected to a load which is determined by the cone-shaped spring operably connec-ted to the ou-ter roll. The outer roll presumably still engages in the straightening of the strand since the outer roll exerts on the strand a force which is determined by the cone-shaped spring and which is less than the straiyhtening force during the stationary casting period. However, since the degree of engagement of the outer roll in straightening is very small as compared with that of the inner roll, straightening is carried out essentially by the inner roll of -the second palr of rolls.
on increase in the straightening roll pi-tch and in the unbending-a.rm lengkh therefore results since the pairs of rolls whlch engage in the straightening of the strand, i.e., the inner and outer rolls, are the first and third pairs of rollsO
B. Conveyance of the Bottom Section of a Strand Through the Multi-Point Straightening Zone When the bottom section of a strand arrives at the second pair of inner and outer rolls, the bottom end of the strand is between the first and second pairs of rolls. The outer roll of the second pair of rolls is 8~
retracted and is subjected to a load which is determined by the cone-shaped spring operably connected to the outer roll. An increase in the straighteniny roll pitch and in the unbending-arm length results since, as in A above, the outer roll exerts on the strand a force which is determined by the cone-shaped spring and which is less than the straightening force during the stationary casting period.
II. Shunting in which the elastic means is a hydraulic cylinder and in which the first and third pairs of rolls are not shunted but the second pair of rolls is shunted during a non-stationary casting period is now described.
A. Conveyance of the Top Section of a Strand When the border between the top and middle sections of a strand is detected by means of tracking as having arrived at the first pair of rolls, both the inner and outer rolls of the second pair of rolls are retracted.
After the top end of the strand has passed through the second pair of rolls, the inner and outer rolls of the second pair of rolls are reverted to their original positions. As a result of retraction, the force to which the inner and outer rolls of the second pair of rolls are subjected during a non-stationary casting period is the stationary roll load. In addition, the force to which the non--shunted first and third pairs of rolls are subjec-ted during a non-stationary casting period is only approximately one half the non-stationary roll load according to the conventlonal straightening process.
An increase in the straightening roll pitch and in the unbending-arm length results due to both a decrease in and an increase in the radii of the curves defined by the inner and outer rolls, respectively.
B. Conveyance ox the bottom Section of a Strand When the bottom end of a strand is deter-mined by means of tracking as having arrived at the firs-t pair of rolls, the inner and outer rolls of the second pair of rolls are retracted. When the border between the bo-ttom and middle sections is detected by means of tracking as _ _ . _ _ _ _ _ . .. _ . _ _ _ _ _ _ .. _ . . .... . ... . .. . .. . .. . . .. . . . . .
having arrived at the third pair of rolls, the inner and t;
outer rolls of the second pair of rolls are reverted to their original positions. As a result of retraction, the force to which the second pair of rolls is subjected during a non-stationary casting period is the stationary roll load. In addition, the force to which the non-shunted first and third paixs of rolls are subjected during a non-stationary casting period is only approximately one halE the non-stationary roll load according to the con-ventional straightening process. An increase in thestraightening roll pitch and in the unbending-arm length results due to, as in A above, both a decrease in and an increase in the radii of the curves defined by the inner and outer rolls, respectively.
In the above description of the two types of shunting, it is presumed that both the top and bottom sections are longer than the straightening roll pitch.
Bow-type continuous casting methods according -to the present invention and a conventional method are now des-cried with reference to the example and the comparativeexample.
Example The essential parts of the low-head CCM of the example according to the present invention are schematically shown in Fig. 2. The continuous casting method ox the present invention was carried out by means of a low-head CCM under the casting parameters given below. The parameters of the low-head CCM were as follows:
A. Basic radius (Rl) ox the curve: 3 m B. Multi-point straightening zone lO:
(1) Straightening points: 15 (2) Radii of pairs of stationary straightening rolls ll:
.. .. .. .. . ..
1~1 R2 : 3100 mm !
R4 : 3650 mm R6 : 4400 mm R8 : 5500 mm Rlo: 7500 mm R12: 11650 mm R14: 26000 mm
(3) Thaoretic radii of pairs of straightening rolls 11 to be shunted during non-stationary casting period:
Rl : 3000 mm R3 : 3350 mm R5 : 4000 mm R7 : 4900 mm Rg : 6400 mm Rll: 9150 mm R13: 16100 mm R15: 67100 mm
Rl : 3000 mm R3 : 3350 mm R5 : 4000 mm R7 : 4900 mm Rg : 6400 mm Rll: 9150 mm R13: 16100 mm R15: 67100 mm
(4) Diameter (r) of straightening rolls 11 and straightening roll pi-tch (p):
r - 230 mm p = 300 mm
r - 230 mm p = 300 mm
(5) Construction of stationary s-traigh-teniny--roll assemblies: shown in Fiy. G.
(6) Construction of movable straightellirlcJ-roll assemblies:
(a) As shown in Fig. 7.
(b) Characteristic of cone-shaped springs 28: deflection of -the springs 28 was æero under a load of up -to 70 tons, enabling the springs 28 to behave as a rigid body under a load of up -to 70 tons; deflection was 1 mm under a load of 100 tons.
C. Machine height H: 3.5 m 28~
The casting parameters during a normal continuous--casting period were as follows:
A. Casting speed: 1.7 m/min.
(high casting speed) B. Cooling condition: moderate cooling so -that the surface temperature and the thickness of the solidified shell of the strand in the multi-point cooling zone were 900C or more and 60 mm or less (at each side of the strand), respectively.
The stationary and non-stationary roll loads were from 28 to 33 tons and from 55 to 116 tons, respectively.
Produced strands having a cross section 250 mm thick and 2000 mm wide were free of internal and external defects and had a high temperature. The life of the straightening rolls, which was calculated on the basis of the non--stationary roll load, was such that the rolls could withstand repeated applications of the non-sta-tionary roll load of 1.5 x 106 times.
Comparative Example Continuous casting in accordance with the method described in the above example was repeated except that all of the straightening rolls were stationary during the stationary and non-stationary casting periods. The ~5 stationary and non-stationary roll loads were from 2a to 33 tons and from 108 to 231 tons, respectively. Strands produced were Eree of internal and external defects, but the non-stationary roll load was, on the average, twlce as high as that of the above example. according to the calculated life of the straightening rolls, the straight-ening rolls could withstand repeated applications of the nonstationary roll load of 2 x 104 times. This value was approximately 1/75 times as low as that of the above example. That is, according to the shunting method, the life of the straightening rolls could be prolonged appro-ximately 75 times as long as in the case of conventional continuous casting.
, . ., :
(a) As shown in Fig. 7.
(b) Characteristic of cone-shaped springs 28: deflection of -the springs 28 was æero under a load of up -to 70 tons, enabling the springs 28 to behave as a rigid body under a load of up -to 70 tons; deflection was 1 mm under a load of 100 tons.
C. Machine height H: 3.5 m 28~
The casting parameters during a normal continuous--casting period were as follows:
A. Casting speed: 1.7 m/min.
(high casting speed) B. Cooling condition: moderate cooling so -that the surface temperature and the thickness of the solidified shell of the strand in the multi-point cooling zone were 900C or more and 60 mm or less (at each side of the strand), respectively.
The stationary and non-stationary roll loads were from 28 to 33 tons and from 55 to 116 tons, respectively.
Produced strands having a cross section 250 mm thick and 2000 mm wide were free of internal and external defects and had a high temperature. The life of the straightening rolls, which was calculated on the basis of the non--stationary roll load, was such that the rolls could withstand repeated applications of the non-sta-tionary roll load of 1.5 x 106 times.
Comparative Example Continuous casting in accordance with the method described in the above example was repeated except that all of the straightening rolls were stationary during the stationary and non-stationary casting periods. The ~5 stationary and non-stationary roll loads were from 2a to 33 tons and from 108 to 231 tons, respectively. Strands produced were Eree of internal and external defects, but the non-stationary roll load was, on the average, twlce as high as that of the above example. according to the calculated life of the straightening rolls, the straight-ening rolls could withstand repeated applications of the nonstationary roll load of 2 x 104 times. This value was approximately 1/75 times as low as that of the above example. That is, according to the shunting method, the life of the straightening rolls could be prolonged appro-ximately 75 times as long as in the case of conventional continuous casting.
, . ., :
Claims (13)
1. A bow-type continuous-casting method, wherein a strand is straightened, at a plurality of straightening points, by means of a plurality of pairs of straighten-ing rolls which are successively arranged in a multi-point straightening zone and, define the radii of the curves, said radii successively increasing in the multi-point straightening zone, characterized in that during a non-stationary casting period in which the top section or bottom section of said strand is conveyed through said multi-point straightening zone, at least one se-lected pair of said straightening rolls is shunted from the defined radius of the curve, thereby increasing the distance between the pairs of straightening rolls, which pairs exert a straightening effect on said strand, and decreasing the straightening points of said multi-point straightening zone.
2. A bow-type continuous-casting method according to claim 1, wherein the basic radius of the curve of said strand is from 3 to 5 m and the number of straight-ening points is from five to fifteen.
3. A bow-type continuous-casting method according to claim 1, wherein said at least one selected pair of straightening rolls shunted from the defined radius of the curve is either an even or an uneven numbered pair or pairs of straightening rolls as seen in the with-drawal direction of said strand.
4. A bow-type continuous-casting method according to claim 1, 2 or 3, wherein said plurality of pairs of straightening rolls comprise a plurality of groups, each group comprising at least three pairs of straightening rolls, and said at least one selected pair of straight-ening rolls is either the second or subsequent pair of straightening rolls of said groups as seen in the with-drawal direction of the strand.
5. A bow-type continuous-casting method according to claim 1, 2 or 3, wherein said strand has a tempera-ture of I, at least 900°C at the completion of multi-point straightening.
6. A bow-type continuous-casting apparatus having a low height and comprising a multi-point straightening zone in which a plurality of pairs of straightening rolls for straightening a strand are stationarily and successively arranged and define curves having successively increasing radii, characterized in that at least one selected pair of said straightening rolls is operably connected to an elastic means for automatically shunting said at least one selected pair of straightening rolls from the defined radius of the curve during a non-stationary casting period in which the top section or the bottom section of said strand is conveyed through said multi-point straightening zone.
7. A bow-type continuous-casting apparatus according to claim 6, wherein said elastic means comprises a hydraulic cylinder.
8. A bow-type continuous-casting apparatus according to claim 6, wherein said elastic means comprises a cone--shaped spring.
9. A bow-type continuous-casting apparatus according to claim 6, wherein the basic radius of the curve said strand is from 3 to 5 m and the number of straightening points is from five to fifteen.
10. A bow-type continuous-casting apparatus according to claim 7 or 8, wherein said at least one selected pair of straightening rolls is either an even or an uneven numbered pair or pairs of the straightening rolls as seen in the withdrawal direction of said strand.
11. A bow-type continuous-casting apparatus accord-ing to claim 7 or 8, wherein said plurality of pairs of straightening rolls comprise a plurality of groups, each group comprising at least three pairs of straightening rolls, and said at least one selected roll is either the second or subsequent pair of the straightening rolls of said groups as seen in the withdrawal direction of the strand.
12. A bow-type continuous-casting apparatus according to claim 8, wherein said cone-shaped spring is secured between a supporting base and supporting frame which is slidably mounted on said supporting base so that said supporting frame is slidably retracted towards a space within said supporting base.
13. A bow-type continuous-casting apparatus according to claim 8, wherein said cone-shaped spring is secured between a supporting base and supporting frame which is slidably mounted on said supporting base so that said supporting frame is slidably retracted towards a space within said supporting base; and said supporting base has a large-diameter base part which defines said space therein and medium-diameter cylindrical part which defines a vertical slot therein; further, said supporting frame supports a bearing of one of the straightening rolls and has a flange which comprises a downwardly protruding rod inserted in and vertically slidable along said vertical slot.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP98964/81 | 1981-06-25 | ||
| JP56098964A JPS58363A (en) | 1981-06-25 | 1981-06-25 | Method and device for curved type continuous casting by leveling at multiple points |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1189281A true CA1189281A (en) | 1985-06-25 |
Family
ID=14233744
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000406037A Expired CA1189281A (en) | 1981-06-25 | 1982-06-25 | Bow-type continuous-casting method and apparatus |
Country Status (8)
| Country | Link |
|---|---|
| EP (1) | EP0068814B1 (en) |
| JP (1) | JPS58363A (en) |
| AT (1) | ATE11495T1 (en) |
| AU (1) | AU531512B2 (en) |
| BR (1) | BR8203701A (en) |
| CA (1) | CA1189281A (en) |
| DE (1) | DE3262130D1 (en) |
| ES (1) | ES513478A0 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AT406746B (en) * | 1998-11-06 | 2000-08-25 | Voest Alpine Ind Anlagen | METHOD FOR CONTINUOUS CASTING OF METAL AND CONTINUOUS CASTING MACHINE HERE |
| DE102013224557A1 (en) | 2013-11-29 | 2015-06-03 | Sms Siemag Ag | Continuous casting plant and method for continuous casting of a metal strand |
| KR101736574B1 (en) * | 2015-06-04 | 2017-05-17 | 주식회사 포스코 | Solidifying apparatus |
| CN112938539A (en) * | 2019-11-26 | 2021-06-11 | 苏政委 | Automatic loading and stacking machine for bagged goods |
| CN113070370A (en) * | 2021-05-03 | 2021-07-06 | 芜湖恒泰有色线材股份有限公司 | Finished product oxygen-free copper rod continuous cold drawing unreels online straightening mechanism |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2144750B1 (en) * | 1971-07-02 | 1976-08-06 | Mannesmann Ag | |
| JPS5180624A (en) * | 1975-01-13 | 1976-07-14 | Nippon Kokan Kk | Haganenorenzokuchuzoho oyobi sonosochi |
| DE2544556C3 (en) * | 1975-10-04 | 1978-09-21 | Demag Ag, 4100 Duisburg | Support roller frame for steel slab caster, especially for curved slab caster |
| DE3011137B1 (en) * | 1980-03-22 | 1981-08-20 | Mannesmann Demag Ag, 4100 Duisburg | Process for controlling the individual drives of a continuous sheet metal multi-roll machine for metal, esp. for steel, and drive arrangement for it |
-
1981
- 1981-06-25 JP JP56098964A patent/JPS58363A/en active Pending
-
1982
- 1982-06-17 AU AU84939/82A patent/AU531512B2/en not_active Ceased
- 1982-06-23 AT AT82303283T patent/ATE11495T1/en not_active IP Right Cessation
- 1982-06-23 DE DE8282303283T patent/DE3262130D1/en not_active Expired
- 1982-06-23 EP EP82303283A patent/EP0068814B1/en not_active Expired
- 1982-06-24 BR BR8203701A patent/BR8203701A/en unknown
- 1982-06-25 CA CA000406037A patent/CA1189281A/en not_active Expired
- 1982-06-25 ES ES513478A patent/ES513478A0/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| ATE11495T1 (en) | 1985-02-15 |
| ES8306969A1 (en) | 1983-06-16 |
| JPS58363A (en) | 1983-01-05 |
| DE3262130D1 (en) | 1985-03-14 |
| BR8203701A (en) | 1983-06-21 |
| EP0068814B1 (en) | 1985-01-30 |
| ES513478A0 (en) | 1983-06-16 |
| EP0068814A1 (en) | 1983-01-05 |
| AU8493982A (en) | 1983-05-19 |
| AU531512B2 (en) | 1983-08-25 |
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