U.S. patent number 3,834,445 [Application Number 05/283,849] was granted by the patent office on 1974-09-10 for continuous casting mold having a breakout sensing and control device.
This patent grant is currently assigned to Vereinigte Osterreichische Eisenund Stahlwerke. Invention is credited to Heinz Raschke.
United States Patent |
3,834,445 |
Raschke |
September 10, 1974 |
**Please see images for:
( Certificate of Correction ) ** |
CONTINUOUS CASTING MOLD HAVING A BREAKOUT SENSING AND CONTROL
DEVICE
Abstract
The invention relates to an apparatus to be used at a continuous
casting plant for preventing the results of a break through of the
solidifying bar. Such apparatus comprises a protective body which
is resistant against liquid metal and immediately below the mould
surrounds the bar shell over at least part of its circumference and
is provided with a cavity open towards the bar shell for receiving
liquid metal, and in said body a sensor connected with an alarm
system for indicating a metal break through so that casting may be
interrupted.
Inventors: |
Raschke; Heinz (Linz-Urfahr,
OE) |
Assignee: |
Vereinigte Osterreichische Eisenund
Stahlwerke (Linz, OE)
|
Family
ID: |
3602822 |
Appl.
No.: |
05/283,849 |
Filed: |
August 25, 1972 |
Foreign Application Priority Data
|
|
|
|
|
Sep 20, 1971 [OE] |
|
|
8129/71 |
|
Current U.S.
Class: |
164/150.1;
164/444; 164/152 |
Current CPC
Class: |
B22D
11/16 (20130101); B22D 11/148 (20130101) |
Current International
Class: |
B22D
11/14 (20060101); B22D 11/16 (20060101); B22d
011/12 () |
Field of
Search: |
;164/152,153,273,150,155,154,151,156,282,88,87,82,281,283MS,283MT,283R,64,63 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Annear; R. Spencer
Attorney, Agent or Firm: Brumbaugh, Graves, Donohue &
Raymond
Claims
I claim:
1. An apparatus for use in a continuous casting plant for
determining if the liquid core of the cast bar has broken through
the outer shell of the bar, the apparatus being positioned adjacent
the casting mould, comprising, a protective body resistant against
liquid metal which is positioned immediately below the mould for
minimizing the flow of any liquid metal that breaks through the
outer shell of the bar onto other parts of the plant, the
protective body surrounding the cast bar over at least that part of
its circumference where break throughs normally occur and being
provided with a cavity therein open toward the cast bar, system
means for indicating a metal break through including, a sensor for
detecting the presence of liquid metal, said sensor being
positioned in the cavity and connected to the system means in a way
as to cause the system means to indicate a metal break through when
liquid metal is present in the cavity.
2. The apparatus set forth in claim 1, wherein the protective body
is releasably attached to the mould.
3. The apparatus set forth in claim 1, wherein the protective body
comprises at least two parts, said parts being displaceable
relative to each other for adaptation to different bar cross
sections.
4. The apparatus set forth in claim 3, wherein the parts of said
body are cooled by circulation of a cooling agent therein.
5. The apparatus set forth in claim 1, wherein for producing a
broad slab with two broad sides and two narrow sides the protective
body comprises two parts, the two parts being positioned on the two
opposite broad sides of the cast slab and each of the parts having
a cavity therein open toward the slab.
6. The apparatus set forth in claim 1, wherein the protective body
is provided at least at its lower edge with a supporting plane for
the bar shell.
7. The apparatus set forth in claim 6, wherein said supporting
plane is formed by a hollow section cooled by circulation of a
cooling agent therein.
8. The apparatus set forth in claim 1, wherein the cavity of the
protective body is provided with a lateral opening through which
liquid steel may flow into a collecting vessel.
9. An apparatus for use in a continuous casting plant for
determining if the liquid core of the cast bar has broken through
the outer shell of the bar, the apparatus being positioned adjacent
the casting mould, comprising:
a protective body resistant against liquid metal and positioned
immediately below the mould, said protective body surrounding the
cast bar over at least a part of its circumference and being
provided with a cavity therein open toward the cast bar;
an alarm signal means with a first terminal connected to the
mould;
a sensor for indicating the presence of liquid metal, said sensor
being positioned in the cavity of said protective body and being
made of a metal wire which is electrically insulated against the
protective body and against the cast bar; and
a power supply with one pole connected to the wire and the other
pole connected to a second terminal of said alarm signal means,
whereby in case of a metal break through, the insulation of the
metal wire is destroyed and an electrically conductive connection
is established between the metal wire and, via the bar, with the
mould, and the alarm signal means is actuated.
10. An apparatus for use in a continuous casting plant for
determining if the liquid core of the cast bar has broken through
the outer shell of the bar, the apparatus being positioned adjacent
the casting mould, comprising:
a protective body resistant against liquid metal and positioned
immediately below the mould, said protective body surrounding the
cast bar over at least a part of its circumference and being
provided with a cavity therein open toward the cast bar;
an alarm signal means with a first terminal connected to said
protective body;
a sensor for indicating the presence of liquid metal, said sensor
being positioned in the cavity of said protective body and being
made of a metal wire which is electrically insulated against the
protective body and against the cast bar; and
a power supply with one pole connected to the wire and the other
pole connected to a second terminal of said alarm signal means,
whereby in case of a metal break through, the insulation of the
metal wire is destroyed and an electrically conductive connection
is established between the metal wire and said protective body, and
the alarm signal means is actuated.
Description
The invention relates to an apparatus at a continuous casting
plant, in particular at a plant for continuous casting of steel, in
which a bar having a liquid core and a solidified bar shell is
drawn out of a water-cooled mould.
In continuous casting of hot liquid metals, in particular in
continuous casting of steel bars, sometimes the liquid metal breaks
through the already solidified bar shell, as a rule immediately
below the mould in the area of a relatively narrow circumferential
zone of the cast bar. By regulating the casting speed, cooling of
the bar and measuring the bar shell thickness, a high operational
safety may be obtained in a continuous casting plant so that the
number of breaks through will remain small; however, such an
occurrence is a great nuisance and therefore feared because when
the metal breaks through the plant parts below the continuous
casting mould, such as supporting and guiding rollers, supporting
construction parts and the like are damaged as the metal welds with
these parts. Frequently it is necessary to remove the supporting
and guiding structures in the vicinity of the mould, as well as the
arrangement for cooling the bar, and to replace them by new parts,
which means that the whole plant has to stand still up to a time of
24 hours. So far it has not been possible to provide for an
apparatus that would prevent such results of a break through.
The invention is aimed at avoiding the described disadvantages. It
is aimed at providing at a continuous casting plant a safety device
for preventing damages when a metal break through occurs. According
to the invention this task is solved by a protective body which
immediately below the mould surrounds at least part of the
circumference of the cast bar shell, said body being resistant
against the liquid metal and provided with a cavity open towards
the bar shell for receiving liquid metal and in which a sensor is
housed which indicates a metal break through.
Advantageously the protective body is releasably attached to the
mould.
The protective body may comprise several parts which are, if
desired, cooled by circulation of a coolant agent, of which always
two parts lying opposite to each other with regard to the bar, are
displaceable against each other so that they may be adapted to
different bar cross sections.
In a plant for producing wide slabs it is sufficient that the
protective body comprises two parts arranged to lie opposite to
each other and adapted to be adjusted only to the broad sides of
the slabs, the cavities at their sides being bordered by walls
adjacent to the margin of the bar shell.
Preferably the protective body is provided at least at its lower
edge with a supporting plane for the bar shell, which is preferably
formed by a hollow section cooled by circulation of cooling
water.
A further embodiment of the invention resides in that the cavity of
the protective body is provided with a lateral opening through
which liquid steel may issue into a collecting vessel.
The sensor for indicating the break through of metal may be made of
a metal wire electrically insulated against the protective body and
against the bar, which wire is connected with one pole of a power
supply; further, an alarm signal is provided which is electrically
connected with the other pole of the power supply and with the
mould or with the protective body, so that in case of a metal break
through the insulation of the metal wire is destroyed and an
electrically conductive connection is established between the metal
wire and the protective body or via the bar with the mould, and the
alarm signal is actuated.
In order that the invention may be more fully understood, several
embodiments thereof shall now be explained with reference to the
accompanying drawings.
FIG. 1 is a vertical sectional view of a continuous casting mould
provided with a device according to the invention showing the
supporting and guiding structure for the bar to be drawn out.
FIG. 2 is a schematical illustration of the device indicating the
breakthrough of steel.
FIGS. 3a and 3b show different embodiments of the metallic
protective body in sectional views;
FIG. 4 is a horizontal sectional view of a metallic protective body
according to the invention used for broad slabs and
FIG. 5 shows a detail regarding the formation and mounting of the
device according to the invention for indicating the break through
of steel.
In FIG. 1 numeral 1 denotes a water-cooled mould of copper, from
which a steel bar 2 with a liquid core 3 and an already solidified
cast bar shell 4 is drawn out over supporting and guiding rollers
5, 6 by means of a not illustrated drawing out device. On both
sides of the bar spraying nozzles 7 are provided for cooling the
cast bar 4 with water. The supporting and guiding rollers 6 may be
mounted in a (not illustrated) stand, while the supporting and
guiding rollers 5 are mounted by a holding means 8 at the lower
edge 9 of the mould 1 oscillating in direction of the bar axis; the
rollers 5 oscillate with the mould. According to the invention a
metallic protective body 10 surrounds the bar circumference between
the rollers 5 and the mould 1. Suitably the body is releasably
mounted at the mould 1 by means of a holding ring 11. The
protective body 10 is formed as a hollow body, whose hollow space
12 is in connection with a not illustrated water supply and water
drain. In the illustrated example the protective body 10 has an
about C-shaped cross section, whereby an upper and a lower cooled
supporting plane 13, 14 for the bar shell 4 is formed, between
which a cavity 15 extends which is open towards the bar shell 4.
Into this cavity 15 surrounding the bar 2, a wire 16 insulated
against the metallic protective body 10 and the bar 2 is inserted;
that part thereof which is guided out of the protective body 10
through a bore is denoted with 16'. This part 16' is connected with
an electrical alarm signal whose system is illustrated in FIG. 2.
The wire 16 present in the cavity 15 comprises, as shown in detail
in FIG. 2, a metal wire 17 and an electrical insulation 18. The
electrical insulation 18 may surround the wire 17 only where it is
in contact with the protective body 10, as illustrated in FIG. 5.
It may, however, also surround the wire 17 over its entire cross
section. The insulation is to be resistant against the radiation
heat of the bar 2 and -- if it surrounds the wire entirely -- has
to be destroyed upon contact with liquid steel, which may take
place either by breaking as a result of heat tensions or by
melting.
The metal wire 17 is connected via a line 17' and a safety fuse 19
with one pole of a power supply 20, e.g., alternating current of 42
volt tension. The other pole of the power supply 20 is connected
via a line 21 and a safety fuse 22 with an alarm signal 23, e.g.,
an audible alarm, a blinker or the like. The alarm signal 23 is
conductively connected with the mass, i.e., with the mould 1 or
with the metallic protective body 10. When the liquid steel 3
breaks through in the bar shell zone 4' (FIG. 1) where ruptures are
most likely to occur as is known by experience, the steel is
collected in the cavity 15 and an electrically conductive
connection is established between the wire 17 and the protective
body 10 or via the bar 2 itself to the mould 1, so that by closing
the circuit 17, 17', 20, 21, 1 or 10, the alarm signal 23 is
actuated. The casting process may then be interrupted by hand or by
stopping the drive for drawing out the bar. It is also possible to
connect a line 24 with a relay switched in parallel or contractor
25 so that a switch is actuated which closes or interrupts a
current conduit 26 which is connected, e.g., with the drive motor
of the bar drawing out means in a manner that at the moment when
the alarm signal 23 is actuated the continuous casting plant is
simultaneously brought to a standstill. Instead of the device
illustrated in FIG. 2 also a thermal element or a radiation
pyrometer may be used, which registers the temperature or light
difference occurring when the bar breaks through, and thus causes
in the same manner an electrical switching so as to stop the
continuous casting plant.
When steel breaks through, the cavity 15 is entirely or partly
filled with steel, which solidifies there. As the steel cannot flow
off downwardly, neither the rollers 5,6 nor the spraying nozzles 7,
nor the supporting stand arranged below can be damaged. The inner
face of the protective body may be provided with a graphite layer
or with another refractory layer so that the steel is prevented
from welding with the protective body. The protective body may be
used several times; only the insulated wire 16 has to be
renewed.
Suitably the protective body is designed in several parts. When
square bars are cast at each bar side a body is provided so that an
annular closed cavity 15 is formed. The individual parts of the
body may easily be removed after a bar rupture, so that the bar may
be drawn out before its complete cooling, if desired after the
broken steel was burnt off by means of a flame cutter. Also when
slabs are produced, the body should be composed of several parts,
so that also an adjustment and adaptation to various bar cross
sections is possible.
According to FIG. 3a the metallic protective body may be composed
of an upper part 27 made of full hematite cast iron and a lower
part 28 made of copper; the lower part forms the lower supporting
plane 14, which is a water-cooled hollow section; in this
embodiment no upper supporting plane 13 is used. FIG. 3b shows a
body made of a hematite cast body 27' and a copper hollow section
28 with a lateral opening 29 for draining liquid steel via a groove
30 into a container not illustrated, so that there is the
possibility to receive the total amount of steel present above the
ruptured place and to guide it away from the rollers 5, 6 or from
the supporting construction.
In FIG. 4 numerals 31, 32 denote metallic protective bodies
arranged at the broad sides of a rectangular slab bar 2, which
bodies are provided with lateral walls 33 apposed to the edge of
the bar shell 4, whereby closed cavities 34,35 are provided which
contain electrically insulated wires 36,37; these wires are
connected with a power supply 20 in the manner already described;
when broad slabs are produced it is not necessary to provide
protective bodies at the narrow sides, because there steel does not
break through.
The cavities 15,34,35 may be connected with a conduit, not
illustrated, through which a gas is supplied which may be used for
cooling the bar shell area 4'; the supplied gas may flow off
downwardly through the supporting plane 14 or through the opening
29. Suitably a non-oxidizing gas is used for this purpose, so that
the formation of scale in the bar shell area 4' or deposits of
scale in the cavities 15, 34,35 are prevented .
* * * * *