U.S. patent application number 13/266210 was filed with the patent office on 2012-02-16 for method and device for guiding and orienting a strand in a continuous casting facility for large-sized round profiles.
This patent application is currently assigned to SMS CONCAST AG. Invention is credited to Thomas Meier, Klaus Von Eynatten.
Application Number | 20120037331 13/266210 |
Document ID | / |
Family ID | 41006180 |
Filed Date | 2012-02-16 |
United States Patent
Application |
20120037331 |
Kind Code |
A1 |
Meier; Thomas ; et
al. |
February 16, 2012 |
Method and Device for Guiding and Orienting a Strand in a
Continuous Casting Facility for Large-Sized Round Profiles
Abstract
The invention relates to a method and a device for guiding and
orienting a strand (5) in a continuous casting facility for
large-sized round sections made of steel or a similar material. In
order to prevent the formation of cracks while the strand is
oriented, the outer surface (15) of the strand is heated from above
and from below inside the orienting track. For this purpose, porous
burners (10, 17) are arranged in the discharge section of the
directing track, the hot gas emitted from said burners flowing
entirely around the outer surface (15) of the strand.
Inventors: |
Meier; Thomas;
(Schaffhausen, CH) ; Von Eynatten; Klaus; (Zurich,
CH) |
Assignee: |
SMS CONCAST AG
ZURICH
CH
|
Family ID: |
41006180 |
Appl. No.: |
13/266210 |
Filed: |
May 30, 2010 |
PCT Filed: |
May 30, 2010 |
PCT NO: |
PCT/EP10/03273 |
371 Date: |
October 25, 2011 |
Current U.S.
Class: |
164/484 ;
164/269 |
Current CPC
Class: |
B22D 11/009 20130101;
B22D 11/16 20130101; B22D 11/0406 20130101; B22D 11/1213 20130101;
B22D 11/1282 20130101; B22D 11/1226 20130101 |
Class at
Publication: |
164/484 ;
164/269 |
International
Class: |
B22D 11/128 20060101
B22D011/128; B22D 11/12 20060101 B22D011/12; B22D 45/00 20060101
B22D045/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 3, 2009 |
EP |
09405092.9 |
Claims
1. A method for guiding and orienting the strand in a continuous
casting facility for large-sized round profiles made of steel or a
similar material, characterised in that the strand surface (15) is
heated within the orienting track.
2. The method according to claim 1, characterised in that the whole
of the strand surface (15) is heated.
3. The method according to claim 1, characterised in that the
heating power is adapted to the expansions occurring locally in the
strand surface (15) along the orienting track.
4. The method according to claim 1, characterised in that the
strand surface (15) is heated in a number of preferably evenly
arranged partial zones (8b, 8d, 8f) of the orienting track.
5. The method according to claims 1, characterised in that the
strand surface (15) is heated by burning an air/gas mixture in a
porous structure (14) and blowing the hot exhaust gasses onto the
strand surface (15).
6. A device for implementing the method according to claims 1,
characterised in that it has at least one porous burner (10, 17)
with a reactor (13) filled with ceramic foam or similar structures,
the hot exhaust gasses of which act upon the strand surface (15),
at least on its upper side.
7. The device according to claim 6, characterised in that the
outlet opening of the reactor cell (13) is oriented to the upper
side of the strand surface (15) so that greater heating takes place
on the upper side of the strand surface than on the lower side of
the latter.
8. The device according to claim 6, characterised in that it has an
orienting driver device (7) located in the outlet side strand guide
region comprising a number of porous burners (10) preferably
arranged evenly distributed and which are fitted in spaces between
the pairs of straightening rolls (7a to 7h) of the orienting driver
device (7).
9. The device according to claim 8, characterised in that they are
provided with at least one porous burner (17) additionally disposed
in front of the orienting driver device (7).
10. The device according to claim 6, characterised in that a tunnel
element (8b, 8d and 8f) at least partially surrounding the strand
surface (15) is assigned respectively to the at least one porous
burner (10, 17) through which these exhaust gasses are directed
around the strand surface.
11. The device according to claim 6, characterised in that the
casting strand (5) passing out of the die (2) is guided through
preferably a number of elongate tunnel elements (6a to 6d) in the
upper section of the guide track in which tunnel elements the
casting strand (5) is, as the case may be, insulated or heated.
Description
[0001] The invention relates to a method and a device for guiding
and orienting a strand in a continuous casting facility for
large-sized round profiles made of steel or a similar material.
[0002] Round profiles are products with an approximately round or
oval cross-section which have a continuously curved outer surface
and so, unlike profiles with a polygonal cross-section, are free
from edges. As a result, there are different requirements for said
round profiles than for profiles with a polygonal strand
cross-section. With the latter it is mainly problematic that the
casting strand cools down more quickly at the edges than on the
wide sides during the solidification process, and this is
associated with the risk of cracks forming in the edge regions.
This risk is largely independent of the format size of the profile,
and it arises in particular at the cross-over from the radius to
the extension of the strand. In order to avoid the formation of
cracks it is necessary to heat the edge regions of the profile by
specifically introducing heat energy along the whole guide track.
This type of method is disclosed in WO 2007/131584 A1.
[0003] This problem does not occur with edge-free profiles because
their mass is distributed evenly over the circumference, and there
are no edges which are cooled from two sides. In this regard the
continuous casting of round or oval profiles is in principle
non-problematic. With large-sized round profiles the problem does
arise, however, in the strand guide that with said profiles the
cooling and solidification of the molten mass takes place more
quickly on the outer surface of the strand in comparison to the
core of the strand. Specifically, the strand must on the one hand
be cooled down very quickly so that the core of the strand is also
cooled and solidified sufficiently. In this way, however, the outer
surface layer of the strand is cooled down all the more
strongly.
[0004] The strand passing out of the die is bent via one or more
orienting points from the perpendicular direction at the die exit
into the horizontal direction. In order to keep the space
requirement and the facility costs small, the smallest possible
curvature radius is sought. During the orienting process this leads
to high compressive stresses on the lower side and to corresponding
tensile stresses on the upper side of the casting strand. In
particular, with large-sized profiles, due to the temperature
ratios, as described, within the strand cross-section, there is a
risk that the tensile stresses cause cracks to form on the upper
side of the strand surface although these regions themselves are
subjected to the same even cooling as the rest of the strand
surface. Moreover, with very large round profiles the casting
speeds are very low. In this way the risk of crack formation is
increased because the surface temperature of the strand is lower
due to the slow casting.
[0005] The object forming the basis of the invention is to avoid
these disadvantages and to provide a method and a device of the
type specified at the start which also guarantees crack-free
bending of the casting strand along the orienting track, even with
large-sized round profiles.
[0006] This object is achieved according to the invention in that
the strand surface within the orienting track is heated at least on
the upper side.
[0007] In this way, in particular the tensile stresses occurring
here can be broken down to such an extent that the strand bears up
without cracks forming while the latter is oriented, while the core
of the strand retains the respectively achieved degree of
solidification largely unchanged. The strand surface is largely
stress-free at the side.
[0008] Nevertheless, for the purpose of a simple mode of operation
the invention makes provision to heat the whole of the strand
surface.
[0009] According to the invention, the heating power can be adapted
to the stresses occurring locally in the strand surface along the
orienting track. In this way it is possible to optimise the mode of
operation of the facility procedurally.
[0010] Within this context provision is also made according to the
invention such that the strand surface is heated in a number of
preferably evenly arranged partial zones of the orienting track. In
this way the heating power can be adapted to the different
requirements in the individual orienting track sections.
[0011] The stresses occurring while orienting the strand are by
nature particularly large in the region of the extension of the
strand guide. For this reason the invention makes provision to heat
the strand surface preferably in the whole orienting track
section.
[0012] For the purpose of even, sensitively controllable heating
which is gentle on the strand surface, the invention also makes
provision such that the strand surface is heated by burning an
air/gas mixture in a porous structure and blowing the hot exhaust
gasses produced onto the strand surface. This results in
flame-free, volumetric burning with easily controllable and stable
burning of the energy carrier, a high degree of conversion of the
energy into radiation energy, and a large control range of the heat
energy introduced and exhaust gasses flowing out over a large
area.
[0013] The device according to the invention for implementing the
method has at least one porous burner with a reactor filled with
ceramic foam or similar structures, the hot exhaust gasses of which
flow around the whole of the strand surface. Since, as known from
experience, the risk of cracks on the upper side of the strand
surface is greater, it is advantageous to orient the outlet opening
of the reactor specifically so that the hot exhaust gasses can
initially heat the region of the strand at greatest risk of
cracking.
[0014] Since the risk of cracking is at its greatest in the strand
guide region on the outlet side, in particular within the orienting
driver device, the invention makes provision to equip the device
with a number of preferably evenly distributed porous burners which
are placed in the spaces between the pairs of straightening rolls
of the orienting driver device. This type of device is on the one
hand space-saving, and on the other hand enables finally tuned
heating of the casting strand.
[0015] With particularly large sizes it is advantageous within the
context of the invention to provide the device additionally with at
least one porous burner disposed in front of the orienting driver
device. The risk of crack formation is thus prevented over a longer
section of the strand guide.
[0016] In the following the invention is described in more detail
by means of an exemplary embodiment with reference to the
drawings.
[0017] FIG. 1 shows the guide and orientation device according to
the invention, shown diagrammatically in the side view, and
[0018] FIG. 2 shows a porous burner for the device from FIG. 1,
also shown diagrammatically as a section and enlarged.
[0019] The guide and orientation device 1 shown in FIG. 1 is part
of a continuous casting facility for producing large-sized round
profiles made of steel or a similar material. The molten steel is
introduced into a die 2 to the die outlet 3 of which a strand guide
4 is connected. The casting strand 5 passing out of the die 2 is
guided in the upper section of the guide track through elongate
tunnel elements 6a to 6d in which the casting strand 5 is, as the
case may be, insulated or heated. These tunnel elements 6a to 6d
can be closed all around or advantageously designed to be open at
the bottom. The first three tunnel elements 6a to 6c can be formed,
for example, such that cooling of the strand running through the
latter is implemented, with a subsequent tunnel element 6d,
however, insulation being brought about without cooling or even
heating of the strand.
[0020] There is disposed in the adjoining section of the guide
track an orienting driver device 7 with pairs of straightening
rolls 7a to 7h. Further narrow tunnel elements 8a to 8g are fitted
between the latter. The casting strand 5 that has meanwhile
hardened on the outside is oriented here with the pairs of
straightening rolls 7a to 7h and introduced to an adjoining
reducing roller plant 9.
[0021] The tunnel elements 8b, 8d and 8f are equipped with porous
burners 10. One of these burners is illustrated diagrammatically in
FIG. 2. The tunnel elements 8b, 8d and 8f have an upper top wall 11
on which the respective porous burner 10 is placed. Preferably, a
wall, not detailed, which is advantageously provided with openings
or the like, is also respectively provided on the lower side of
these tunnel elements 8b, 8d and 8f so that these tunnel elements
insulate better.
[0022] This porous burner 10 substantially consists of a burnable
gas and air supply connection 12 and a reactor cell 13 connected to
the latter and which is filled with a filler 14 made of porous
ceramic foam. Here the combustion reaction of the pre-mixed
burnable gas/air mixture runs off resulting in flame-free
volumetric combustion. The exhaust gas flowing out of the reactor
cell 13 flows around the whole of the casting strand 5 and
advantageously heats the strand surface 15 in the upper region more
than on the lower side without heating the core of the strand 16 at
the same time to an appreciable degree.
[0023] The porous burners 10 enable very easily controllable and
stable combustion of the energy carrier, a very high degree of
conversion of the energy into radiation energy, an exhaust gas
flowing out evenly and over a large area, as well as a very high
adjustment range of the heat energy introduced so that the heating
power of the individual burners can easily be adapted to the local
requirements.
[0024] An additional porous burner 17 is disposed in the elongate
tunnel element 6d of the strand guide in front of the orienting
driver device 7. It is formed in exactly the same way as the porous
burners 10 of the orienting driver device 7, and like the latter
also has the function of heating the strand surface 15 in order to
avoid the risk of crack formation here too. Since this risk
increases as the solidification process progresses, it is in any
case advantageous to arrange the porous burners 10 and 17 in the
outlet side region of the strand guide in which the strand surface
has already hardened to a considerable degree. Within this context
other burner arrangements are needless to say conceivable inside
and outside of the orienting driver device, respectively adapted to
the respective conditions.
[0025] It is also possible within the framework of the invention to
design the burners differently from the embodiment described in so
far as they are suitable for heating the whole of the upper and
lower side of the strand surface evenly. In this regard the
described embodiment has the advantage that the hot exhaust gases
flowing out of the reactor 13 heat the upper side of the strand
which is most greatly at risk of cracks, whereas the lower side
which is less at risk of cracks is only heated subsequently by
exhaust gases which are not quite as hot.
[0026] With the individual burners the burner output is controlled
dependently upon their position in the orienting track. For this
purpose temperature sensors 18 are provided along the strand
guide.
[0027] The facility described is equipped with a strand guide
continuously bent from the die outlet 3 to the outlet from the
orienting driver device 7.
[0028] However, the invention can also needless to say be applied
to facilities the strand guide of which, after the die outlet,
initially runs perpendicularly so as only then to pass into a bent
guide track.
[0029] Theoretically, heating of the strand surface could also only
take place on its upper side in order to reduce these tensile
stresses occurring when stretching the strand.
* * * * *