FORM 2
THE PATENT ACT 1970
(39 OF 1970)
&
The Patent Rules, 2003
COMPLETE SPECIFICATION
(See Section 10 and Rule 13)
1 TITLE OF THE INVENTION :
A GRADE SEPARATOR FOR CONTINUOUS CASTING OF STEELS.
2 APPLICANT (S)
Name : JSW Steel Limited.
Nationality : An Indian Company.
Address : Jindal Mansion, 5-A, Dr. G. Deshmukh Marg ,Mumbai - 400 026,
State of Maharastra, India.
3 PREAMBLE TO THE DESCRIPTION
COMPLETE
The following specification particularly descibes the invention and the manner in which it is to
be performed.

FIELD OF THE INVENTION:
The present invention relates to continuous casting of metals and in particular to a grade separator device and a process for continuous casting of metals involving such separator device. The invention is directed to facilitate yield in continuous casting of various grades of steel eliminating downtime and also avoiding/minimizing downgrading of casting quality due to mixed grade casting at the time of change over of grade from one heat to other while both are cast in the same caster-mould into slabs. The separator plate of the invention is directed to favour physically separating the molten steel of a second grade in sequence from the first one, and in the process avoid the limitations of continuous casting including downgrading the casting quality and also loss of valuable production time and efforts apart from improving the sequence length and metal yield in mould which in turn further increase the productivity of the casting shop.
BACKGROUND ART
It is well known in the art of continuous casting of steel slabs that the caster involves , teeming of liquid metal on short mould with false bottom, through which partially solidified slab is continuously drawn at the same rate, at which metal is being poured. The continuous caster imposes several constraints on primary process flow. Changes from one grade to another in the course of a casting sequence necessitate a certain amount of mixing of grades in the, tundish. In most of the occasion, the portion of the cast product corresponding to the "mix zone" is of inferior quality. Some grades have such radically different chemistries that they cannot follow one another in a casting sequence unless the tundish is replaced.
Casting dissimilar grades can be handled in several different ways. The present practice is simply to stop the caster when the first grade is finished and to restart it with the next grade as a new sequence. This method prevents mixing in either the tundish or the strand, so there is no intermixed steel to be downgraded. However, production time is lost to restart the caster. In addition, yield losses are incurred due to quality problems at the end and start of the cast strands. Another method involves only a simple "ladle change". In this method, "new" steel flowing from the next ladle will first mix with "old" steel left in- the tundish from the previous heat. Stee! then flows into the mold, where it undergoes further mixing in the long liquid pool in the strand while it solidifies. This method avoids losses in productivity, but produces the maximum length of intermixed steel. But the users hardly
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agree to accept for the intermixed steel. Casting conditions should be chosen to either minimize the amount of intermixed steel, or to optimize the mixing according to the market order or acceptance criteria of users. These methods are only applicable under situations when production capacity is not limited by the caster and close chemistry grades are cast.
There has been therefore been a continuing need in the art for developing continuous slab casting that would eliminate the limitations of the existing method of casting of different grades of steel having different chemistries, obtained in sequence from successive heats based on requirements, and at the same time achieve improvement in the caster yield eliminating mixing of the two different grades cast in the same mould, by increasing sequence length and reducing mix-up length in slabs.
OBJECTS OF THE INVENTION
Thus the basic object of the present invention is, therefore, directed to avoid limitations of the existing method of continuous casting of different grades of steel having different chemistries as discussed above and also provide for increasing the productivity of the casting shop.
A specific object of the present invention is directed to provide for developing the art of continuous casting involving simple and cost-effective means which would further extend the casting sequence length and minimize slab downgrading during mixed grade casting and also in the process increase the caster yield.
A further object of the present invention is directed to increase the sequence length of the continuous caster from existing number of heats being cast in conventional practice.
A still further object of the present invention is directed to provide for a simple and convenient to use separator in continuous caster, which would enable maintain the various grades of the cast product separated from one another and would be adapted for such purposes with respect to the mould openings for the continuous casting and advantageously completely prevent mixing of the slabs cast from liquid metal obtained from two different heats in sequence and also further prevent mixing of the grades in the strand.
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A still further object of the present invention is directed to provide for a separator device in continuous caster, which would improve/optimize the cut length of slabs minimizing mixing of grades.
Yet another object of the present invention is directed to provide for a separator device in continuous caster, which would favour reducing substantially the mixed up length in cast slabs from the ususal 8-10 meters to 1 meter at each end of the slab.
A still further object of the present invention is directed to provide for a separator device in continuous caster, involving selective steel and thus favouring employing discontinuous array of metal plates such that its weight sufficiently reduced so as to facilitate easier handling of the same in the hot environment adjacent to the mould.
A still further object of the present invention is directed to provide for a separator plate in continuous caster, which would be directed to achieve higher productivity and yield of the continuous caster, without any interruption or loss of production caused due to said mixing of metal for successive heats of different chemistry in sequence by preventing/minimizing the mixing of grades and the increase of metal in mould achieved from existing 65% to a level of around 84%.
SUMMARY OF THE INVENTION
The according to the basic aspect of the of the present invention there is provided a separator device for use during tundish flying comprising:
a separator plate having stopper rods and anchor arrangement adapted to fit exactly with respect to the mould and adapted for (i) joining of the upper and lower slabs (ii) preventing mixing of the grades in the strand and
also (iii) maintaining a selective clearance on each of the narrow faces and the broader faces of the section to be cast.
According to a further aspect of the present invention the grade separator device is obtained of MS steel and Torr steel.
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A still further aspect of the present invention provides a grade separator device wherein said separator plate has been adapted such as to maintain selectively about 25mm clearance on each of the narrow face and 15mm on each of the broader faces of the section to be cast.
Another aspect of the present invention is directed to a process for carrying out continuous casting of metals with better productivity comprising:
introducing a grade separator device and positioning the same into the mold inlet opening immediately following completion of the introduction of a first grade of the molten steel into the mold and before the introduction of a subsequent second grade to thereby achieve physical separation of the said first and second grades of molten steel along with enhancing the cooling rate and solidification at the junction there between the said first and the second grades of the molten steel.
In the above process for carrying out continuous casting of metals with better productivity involving the grade separator is carried out such that the stopper rods and anchor arrangements of MS steel and Torr steel are used for attending atleast one of (i) joining the upper and lower slabs (ii) completely preventing mixing of the grades in the strand and (iii) to maintain a desired clearance on each of the narrow face and on each of the broader faces of the section to be cast.
Advantageously, in the above process for carrying out continuous casting of metals with better productivity it is possible to provide a discontinuous array of metal plates during continuous casting, the plate weight thereby being substantially reduced and thereby favouring easy handling in hot environment adjacent the mould.
The present invention further favours the requirement of improvement of caster yield, in continuous casting of different grades by selectively providing the separator plate, wherein the sequence length of could be increased from existing 7 heats to about 11 heats under the present invention.
According to yet further aspect of the present invention it is possible to improve the caster yield, in continuous casting of different grades by way of the selective provision of a
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separator plate whereby the mixed up length in slab could be reduced from 8-10 meters to 1 meter at each end of the slab and the improvement in cut length optimization was also achieved.
A further aspect of the present invention also directs to improvement of caster yield and increasing the sequence length of successive heats comprising different grades/chemistries, in continuous casting by stated selective provision of the separator plate whereby the metal in mould could be increased from existing 65% to 84% in the present invention which in turn increased the production of the caster.
The present invention and its objects and advantages are described in greater detail with particular reference to the accompanying figure.
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
Figure 1: is an illustration of the constructional feature of the separator plate adapted for the high yielding continuous casting of different grades without mixing, according to the present invention.
DETAILED DESCRIPTION OF THE INVENTION WITH REFERENCE TO ACCOMPANYING FIGURES
As discussed herein before, the present invention advantageously combines benefits of both the methods i.e. either by restarting a new sequence for a new grade of steel or to adopt a ladle change over without affecting the productivity, by way of providing for the grade separator at the time of tundish flying i.e. quick change of tundish in the same sequence. The grade separator device and the process of continuous casting using the same is detailed hereunder.
Reference is now invited to accompanying figure 1 which illustrates the features of the separator plate used in the invention directed to high yield continuous casting of different grades of steel in sequence. The grade separator device as illustrated in the figure has been developed for positioning into the mold inlet opening immediately following completion of the introduction of a first grade of molten steel into the mold and before the introduction of a second grade for physically separating the first and second grades of molten steel and for
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enhancing the cooling rate and solidification at the junction between the said first and the second grades of molten steel. The separator plate has been provided with and developed involving selective use of MS plates and Torr steel such as to fit exactly into the mould. The stopper rods (SR) and the anchor arrangements (AA) in the separator plate provide for the desired joining of the upper and lower slabs. The continuous casting involving such separator device is also capable of completely preventing mixing of the grade in the strand. In keeping with a preferred aspect of the invention, the separator plate has been developed such as to maintain 25mm clearance on each of the narrow face and 15mm on each of the broader faces of the section to be cast. Thus by way of the involvement of the separator device in continuous casting it is possible to employ discontinuous array of metal plates, whereby the weight is sufficiently reduced so as to facilitate relatively easy handling in the hot environment adjacent to the mold.
It is thus possible by way of the present invention to avoid limitations of the existing method of continuous casting of different grades of steel having different chemistries as discussed above and also provide for increasing the productivity of the casting shop. The invention would favour developing the art of continuous casting involving simple and cost-effective means and would further extend the casting sequence length and minimize slab downgrading during mixed grade casting and also in the process increase the caster yield. Importantly the invention is found to favour increasing the sequence length from 7 heats to 11 heats, reducing the mix-up length in slab from 8-10mts. to 1 mt. at each end of the slab. Further, it is noted that the cut-length optimization has improved following the use of the separator device. Also, the metal in the mould increased from 65% to 84% which in turn further increased the productivity of the casting shop. Advantageously also, the invention favours easier handling of the produce in the hot environment adjacent to the mould apart from achieving higher productivity and yield of the continuous caster, without any interruption or loss of production.
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WE CLAIM:
1. A grade separator device for use during tundish flying comprising:
a separator plate having stopper rods and anchor arrangement adapted to fit exactly with respect to the mould and adapted for (i) joining of the upper and lower slabs (ii) preventing mixing of the grades in the strand and also (iii) maintaining a selective clearance on each of Mhe narrow faces and the broader faces of the section to be cast.
2. A grade separator device as claimed in claim 1 wherein the same is obtained of MS steel and Torr steel.
3. A grade separator device as claimed in anyone of claims 1 or 2 wherein said separator plate has been adapted such as to maintain selectively about 25mm clearance on each of the narrow face and 15mm on each of the broader faces of the section to be cast.
4. A process for carrying out continuous casting of metals with better productivity
comprising:
introducing a grade separator device and positioning the same into the mold inlet opening immediately following completion of the introduction of a first grade of the molten steel into the mold and before the introduction of a subsequent second grade to thereby achieve physical separation of the said first and second grades of molten steel along with enhancing the cooling rate and solidification at the junction there between the said first and the second grades of the molten steel.
5. A process for carrying out continuous casting of metals with better productivity as claimed in claim 4 wherein the grade separator device used is as claimed in anyone of claims 1 to 3.
6. A process for carrying out continuous casting of metals with better productivity as claimed in anyone of claims 4 or 5 wherein the stopper rods and anchor arrangements of MS steel and Torr steel are used for attending atleast one of (i) joining the upper and lower slabs (ii) completely preventing mixing of the grades in the strand and (iii) to maintain a desired clearance on each of the narrow face and on each of the broader faces of the section to be cast.
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7. A process for carrying out continuous casting of metals with better productivity as claimed in anyone of claims 4 to 6 wherein by providing discontinuous array of metal plates during continuous casting, the plate weight is substantially reduced and thereby favouring easy handling in hot environment adjacent to the mould.
8. A process for carrying out continuous casting of metals with better productivity as claimed in anyone of claims 4 to 7 providing for one or more of (i) increase in sequence length, (ii) reducing the mix-up length in slab, (iii) improving the cut-length operation and (iv) increasing the metal in the mould and thereby increasing the productivity of the process.
9. A grade separator device for use during tundish flying and a process for carrying out continuous casting of metals with better productivity using said device substantially as herein described and illustrated with reference to the accompanying figure.
Dated this 2nd day of February, 2007. Anjan Sen
Of Anjan Sen & Associates (Applicants Agent)
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ABSTRACT
A GRADE SEPARATOR FOR CONTINUOUS CASTING OF STEELS.
A grade separator device and a process for continuous casting of metals involving such a separator device, directed to facilitate yield in continuous casting of various grades of steel eliminating downtime and also avoiding/minimizing downgrading of casting quality due to mixed grade casting at the time of change over of grade from one heat to other while both are cast in the same caster-mould into slabs. The separator plate of the invention is directed to favour physically separating the molten steel of a second grade in sequence from the first one, and in the process avoid the limitations of continuous casting including downgrading the casting quality and also loss of valuable production time and efforts apart from improving the sequence length and metal yield in mould could be increased from existing 65% to about 84% which in turn further increase the productivity of the casting shop. Figure 1.
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