Note: Descriptions are shown in the official language in which they were submitted.
This invention concerns a slide gate of a casting ladle
or similar container such as a tundish for molten steel or
like other molten metal and, particularly, it relates to a
slide gate having a gas supply or introduction mechanism.
DESCRIPTION OF THE ACCOMPANYING DR~INGS
hereinafter, the invention will be described in more
detail by referring to the accompanying drawings, by which
the foregoing and other objects, as well as the features
of this invention will be made clearer, in which:
Figure 1 is an explanatory sectional view of an example
of a conventional 2-plate slide gate system having a gas
introduction mechallism and applied to a casting ladle;
Figure 2 is an explanatory view of cracks developed in
ttle conventional slicle plate;
Figure 3 is an explanatory sectional view of a 3-plate
- slide gate system having a gas introduction mechanism as a
preferred embodiment according to this invention;
Figure 4 is an explanatory sectional view of an essen-
tial part of a slide plate in a 2-plate slide gate system
as other embodiment according to this invention; and
Figure 5 is an explanatory sectional view of an
essential part ox a slide plate in a 2-plate slide gate
system as a still other embodiment according to this
invention.
~3ACKGROUND OF THE INVENTION
A slide gate of a type having a gas supply mechanism
for introducing the gas into molten steel accommodated
in a casting ladle has been known, for instance, by U.S.
Patent No. 3,581,948.
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As shown in Figure 1, the conventional slide gate 100
of the type mentioned above comprises a slide plate 104
made of refractory rnaterial and having a generally frusto-
conical aperture 103 in which a gas-permeable refractory
member 101 also of a frustconical shape is fitted by way
ox cement mortar 102, and a gas introduction pipe 108 made
of metal and having at its upper end a flanged portion 107
secured to the lower face 105 of the slide plate 104 by
way of cement mortar 106. A stationary plate 109 having
an aperture 114 aligned with an aperture 113 in the top
nozzle 112 situated in a well block 111 of a casting ladle
110 is secured to the bottom of the casting ladle 110 by
way of a metal frame member 115. A metal plate or slider
116 is secured to the slide plate 10~ and a submerged
nozzle 117 by way of the cement mortar 106. The slide
plate 104, the submerged nozzle 117, the gas introduction
pipe 108 and the metal plate 116 can be displaced by a
driving means (not shown) in a direction A or B between
a block position at which the gas-permeable refractory
member 101 is opposed to the outlet aperture 118, con-
stituted by the apertures 113 and 114, in the casting
ladle 110 (shown in Figure 1) and an open position at
which an aperture 119 in the slide plate 10~ and an
aperture 120 in the submerged nozzle 117 are aligned with
the outlet aperture 118. A cut-out portion 121 is formed
to the frame member 115 for allowing the submerged nozzle
11.7 and the gas introduction pipe 108 to be displaced in
the direction A or B.
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In a case where the slide plate 104 is situated at the
block position shown in Figure 1 in the slide gate device
100, a gas introduced from the gas introduction pipe 108
into the output aperture 118 through the gas-permeable
refractory member 101 serves to prevent the solidification
of molten steel in the aperture 118, remove nonmetallic
sludges from the aperture 118 and control the temperature
of the molten steel in the casting ladle 110.
However, in the conventional type of slide gate 100,
the mortar 106a in a region 123 between the lower face 105
of the refractory slide plate 104 and the upper flange 107
of the gas introduction pipe 108 as well a.s the upper :Eace
122 of the metal plate 1].6 is dr.ied to Norm a gap in the
region 123, and there is fear that a part of the gas intro-
duced frown the gas introduction pipe 108 may leak through
the region 123, for instance, in the direction shown by
the arrow C. Such a gas leak will reduce the amount of
the gas introduced into the outlet aperture 118 and thus
make it insufficient to obtain the above-mentioned effects
by the introduction of the gas.
In addition, since the aperture 103 formed in the
slide plate 104 so as to receive the gas-permeable refrac-
tory member 1~1 therein is in the form of a generally
cylindrical penetrating hole, there is fear that cracks
124 rnay be produced by thermal stresses or corrosions due
to the molten steel at the periphery of the aperture 119
may reach the aperture 103 as shown in Figure 2 especially
when the aperture 103 is situated near the aperture 119.
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The cracks 124 may result in a great amount of gas leak
to impair the effects attained by the introduction of gas.
Furtnermore, if the cracks 124 should actually develop, it
may cause a risk that the gas is blown through the cracks
12~ and the aperture 120 of the nozzle 117 into a mold
during discharge of the molten steel from the nozzle 117.
SUMMARY OF THE INVENTION
This invention has been made in view of the foregoinc3
problems and the object thereof is to provide a slide gate
capable of ensuring the introduction of a gas at a prede~
terrnined flow rate, with less fear of gas leak, into the
outlet aperture oE the casting ladle or similar container.
This object can be attained in accordance with this
invention by a slide gate of a casting ladle or similar
container having an outlet aperture or discharging a
molten metal accommodated therein, in which the slide gate
comprises a slide plate horizontally, slidably disposed at
a lower end of the outlet aperture for movement between a
first position to block the discharge of the molten metal
from the outlet aperture and a second position to allow
the discharge of the molten metal from the outlet aperture,
the slide plate having a recess extending into the upper
face thereof, in an area of the upper Eace which is in
alignment with the lower end of the outlet aperture when
the slide plate is set at the first position; a gas-
permeable refractory member disposed in the recess; and
a gas passage means opening into the recess so as to
introduce a gas into the outlet aperture through the gas
permeable refractory member.
DESCRIPTION OF PREFERRED EMBODIMENTS
Figure 3 illustrates a 3-plate slide gate system l as
a preferred embodiment according to this invention. The 3-plate
slide gate l comprises an upper stationary plate 5.secured to a
well block 3 and a top nozzle 4 of a casting ladle or similar
container such as a tundish 2 by means of cement mortar or the
like, a lower stationary plate 6, a submerged nozzle 7, both
ox the lower stationary plate 6 and the submerged nozzle 7 being
supported by adequa-te support means (not shown) so as to be
stationary relative to the upper stationary plate 5, and a
slide plate 8 slidable to the upper and lower stationary
plates 5, 6 in the direction D or E. An outlet aperture 12
comprising a hole 10 in the top nozzle 4 continuously extended
from an aperture 9 in the well block 3 and an aperture il in
the upper stationary plate 5 is vertically aligned with an
aperture 13 in the lower stationary plate 6 and an aperture la
in the submerged nozzle 7~
The slide plate 8 has a penetrating hole 15 allowing
the discharge of molten metal such as molten steel accommodated
in the casting ladle through the outlet aperture 12, as well as
a recess 17 and a lateral penetrating hole 18 communicated
with the recess 17 constituting a gas introduction mechanism
16. The recess 17 is opened at the upper face of the slide
plate 8 so as to be able to be opposed to an lower end of the
Il 2~a~27~
outlet aperture 12 and is closed at the lower face side of the
slide plate 8. A metal member l9 is secured by means of cement
mortar to the bottom wall of the recess 17. A gas-permeable
refractory member 20 is secured by means of cement mortar to the
inside of the recess 17 above the metal member 19. The metal
member l9 is formed on a circumferential edge thereof with
an annular upward protruding portion 21, and the protrusion 21
is fitted and fixed to a complementary circular or annular step
or depression 27 of the gas-permeable refractory member 20 by
means of cement mortar so as to define a disc-like space 24
between a lower face 22 of the gas-permeable refractory member
20 and an upper face 23 of the metal member 19, as well as to
make an upper face 25 of the gas-permeable refractory member
20 in flush with the upper face 26 of the slide plate 8. The
sectional shape of the recess 17 and of the members 19 and
20 just fitted in the recess 17 may be any other configurations
such as a polygonal shape instead of a circle.
The lateral hole 18 formed in the slide plate 8 opens
at one end thereof to a lower portion of the circumferential
wall or surface 28 of the recess 17 and opens at the other end
thereof to one end face 29 of the slide plate 8 crossing in
perpendicular to the sliding directions D, E of the slide plate
8. A metal pipe 30 for gas introduction is fitted and fixed
gas-tightly in the lateral hole 18 by means of cement mortar.
The inserted end 30a of the metal pipe 30 protrudes into the
recess 17 so as to oppose to the space 24 in the recess 17 and
is firmly fitted to the aperture l9a in the metal member 19.
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The gas introduction mechanism 16 c:omprises the recess
17, the gas-permeable refractory member 20, the metal member 19
and the gas introduction pipe 30 fitted in the lateral hole 18,
and the gas passage means for the yas introduction comprises the
gas introduction pipe 30 fitted in the lateral hole 18. The
leading end 19a of -the gas introduction pipe 30 may be fitted
in the lateral hole 18 instead of being protruded into the recess
17. In this case, the pipe 30 and the lateral hole 18 con
sti-tute the gas passage means. Further, the leading open end
l9a of the gas introduction pipe 30 may be communicated with
the hole 18 a-t the end face 29 of the slide pla-te 8 by way of a
metal support frame 31 or the like in a gas-tight manner instead
of being fitted in the hole 18. In this case, the gas passage
means is substantially composed of the hole 18.
Although the provision of the metal member 19 is not
always necessary, it is preferred to engage and fix the gas-
permeable refractory member 20 to the recess 17 in such a way
that the space 2~ is formed below the lower face 22 of the gas-
permeable refractory member 20 in order to introduce the gas
from the gas passage means toward a side of the lower face 22
of the member 20. Instead of forming the space 24, a lateralhole of a relatively large diameter may be provided in a lower
portion of the gas-permeable refractory member 20 to introduce
the gas from the gas passage means through the lateral hole.
The gas introduction pipe 30 may be made of refractory
material instead of metal provided that sufficient heat-
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resistivity, mechanical toughness or strength or the like can beexpected.
A displacing means 32 such as a hydraulic cylinder
is provided for displacing the slide plate 8 in the direction
D or E between the position where the aperture 15 aligns with
the apertures 12, 13 and 14 and the position where the gas-
permeable refractory member 20 opposes to the aperture 12 (the
position shown in Figure 3).
The well block 3, the nozzles 4, 7 and the plates S,
6, 8 are made of refractory material, for instance, comprising
by weight oP alumina and lO % by weight of silica in -this
embodiment but any other conventional refractory materials
rnay be used.
The slide gate 1 having thus been constituted is
operated in the rnanner described below.
Upon closing the outlet aperture 12 of the casting
ladle 2, the slide plate 8 is displaced slidingly by the cylinder
device 32 in the direction D to a predetermined position at
which the gas-permeable refractory member 20 of the gas intro-
duction mechanism 16 just opposes to the outlet aperture 12
lshown in Figure 3). A gas, heated to a predetermined tempera-
ture if desired, is supplied from a gas supply means such as a
pump [not shown) to the pipe 30 in the direction F. The gas
may be an inert gas such as nitrogen or argon and, if desired,
oxygen or air. The gas fed to the pipe 30 is introduced from the
opening at the end 30a of the pipe 30 into -the space 24 in the
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recess 17 and then through the gas-permeable reiractory member
20 into the outlet aperture 12. The gas thus introduced or blown
into the outle-t aperture 12 gives various effects. For instance,
it causes the molten steel in the outlet aperture 12 to flow
upwardly out of the aperture 12 thereby preven-t the solidification
of the molten steel in the outlet aperture 12, as well as
removes nonmetal impurities or sludges from the aperture 12
to the upper part of the ladle 2 by the upward flow of the gas
passing through the aperture 12.
In the slide gate 1, since the recess 17 of the slide
plate 8 opens substantially only at the upper end thereof, the
gas entering the recess 17 flows through the gas-permeable
refractory member 20 toward the upper or open end of the recess
17, therefore substantially all the gas supplied through the
pipe 30 can be introduced or blown at a predetermined flow rate
into the outlet aperture 12~
Furthermore, in the slide gate 1, since the gas-
permeable refractory member 20 is disposed in the recess 17
having the bottom wall, there is li-ttle fear tha-t cracks may
be developed over the entire part of the slide plate 8.
Upon discharging the molten steel from the casting
ladle 2, the slide plate 8 is displaced slidingly by the
actuation of the cylinder device 32 in the direction E to a
predetermined position at which the aperture 15 in the slide
plate 8 is aligned with the apertures 12, 13, 14.
In the slide gate 1, since the gas introduction pipe
30 is extended in perpendicular to the end face 29 of the slide
plate 8 and along the sliding direction D, E of the slide plate
8, the gas introduction pipe 30 can be moved into and out of
the space 8a between the pla-tes 5, 6 accompanying the displacement
of the slide plate 8 in the direction D or E and, accordingly, no
additional space or recess such a portion 121 of Figure 1 is
required for the movement of the gas introduction pipe 30.
The slide gate 1 is constituted in the form of a
3 plate slide gate system in this embodiment but it may be
in the form of a 2-plate system in which the plate 6 ancl the
submerged nozzle 7 are made movable integrally with the slide
plate 8 in the direction D or E. That is, the slide gate 1
may be constituted as a 2-plate slide gate system similar to the
slide gate shown in Figure 1 in which the slide plate 104 and
the gas introduction mechanism in Figure 1 is replaced with the
slide plate 3 and the gas introduction mechanism 16 shown in
Figure 3, In this case an appropriate cut-out portion will be
formed in the frame 115 to pass the pipe 30 therethrough.
In the case of a 2-plate slide gate system, a gas
introduction pipe 33 may be disposed through the bo-ttom wall
36 of the recess 35 in a slide plate 34 as shown in Figure 4,
in which members or components similar to those in Figures 1
and 3 carry the same reference numerals. In Figure.4, a member
37 similar to the metal member 19 of Fiyure 3 has a central
opening 38, and the upper end 39 of a gas introduction pipe 33
is firmly fitted in the opening 38 of the metal member 37 as
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a flange. Cement mortar 47 is filled to ensure gas-tight seals
between a circumferential wall 40 of the recess 35 and a
circumferential surface 41 of the gas permeable refractory
member 20, and between the circumferential wall 40 of the recess
35 and an outer circumferential surface 42 of the petal member
37, as well as between an upper face 43 of the bottom wall 36
of the recess 35 and a lower face 44 of the metal member 37 and
between the circumferential wall of the aperture 45 in the slide
plate 34 and an outer circumferential surface 46 of the gas
introduction pipe 33.
The slide plate 34 is made slidable relati.ve to a
frame member 115 in thy direction vertical to the plane of the
drawing paper of Figure 4 and, when it is set at a predetermined
position at which the gas-permeable member 20 opposes to the
outlet aperture 118 (Figure 1), the discharge of the molten
steel is blocked and the gas is blown into the outlet aperture
118.
Since the gas introduc-tion pipe 33 opens to the
recess 35 in this slide plate, mortar sealing is formed over
a longer region and the fear of gas leak can be reduced or the
amount of gas leak, if any, can be decreased. In addition,
since the slide plate 34 is reinforced with the metal member
37 and the gas introduction pipe 33, there is less fear of
: developing large cracks in the slide plate 34.
As shown in Figure 5, the thickness of the bottom wall
49 of the recess 35 may be increased and a thick metal plate
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51 may be secured to the lower face of a refractory slide plate
member 50 in order to increase the strength of the slide plate
48 at the portion near the recess 35. The slide plate 48 can
be displaced relative to the metal frame member 115 (not shown
in Figure 5) in the direction vertical to the plane of the
drawing paper of Figure 5 in the same manner as the slide plate
34 shown in Figure 4.
In the slide gate according to this invention, the gas
may be.blown into the molten steel between the sliding surfaces
even when the molten steel is being d.ischarged as well as during
the interruption of the discharge of the molten steel. Further,
the gas flow may also be given upon transfer or displacement
of the slide plate so as to reduce the frictional resistance
at the s ding surfac s.
