FERMETURE DU CANAL DE VIDANGE D'UNE CUVE DE COULEE DE METAL

CLOSURE OF THE DISCHARGE CHANNEL OF A METAL CASTING VESSEL

Abrégé français

L'invention concerne un type de dispositif formant robinet (2) installé dans le fond (1) d'une cuve de coulée de métal dotée d'une ouverture. Ce dispositif comprend un corps de canal (3) dans lequel un canal (4) s'étend dans le prolongement du fond, et dont le côté présente un évidement symétrique rotatif (5) qui s'étend transversalement dans le canal (4) ; et un corps de fermeture rotatif (6)prévu dans l'évidement (5) et doté d'un orifice transversal (7) à la même profondeur que le canal (4), orifice fermant et ouvrant le canal (4) lorsque le corps de fermeture (6) est tourné. L'amélioration consiste en ce que l'extrémité (8) du corps de fermeture (6) est articulée sur le fond (9) de l'évidement (5) et en ce que la surface de contact entre le corps de fermeture (6) et l'évidement (5) est symétrique en rotation et est plus petite que la surface de rotation de l'évidement (5).

Abrégé anglais

The invention relates to a cock arrangement type (2) that is fitted in the
bottom (1) of a metal casting vessel provided with an opening, comprising a
channel body (3), through which a channel (4) runs, continuing the opening of
the bottom, and the side of which has a rotationally symmetric recess (5) that
extends transversally through the channel (4); and a rotatable closure body
(6) that is fitted in the recess (5) and has a transversal hole (7) at the
depth of the channel (4), the hole closing or opening the channel (4) when the
closure body (6) is rotated. The improvement is achieved so that the end (8)
of the closure body (6) is hinged to the bottom (9) of the recess (5) and that
the contact surface between the closure body (6) and the recess (5) is
rotationally symmetric and smaller than the rotation surface of the recess (5).

Revendications

5
Claims
1. A cock arrangement (2) fitted at the bottom (1) of a metal casting vessel
that is provided with an opening, comprising a channel body (3), through
which a channel (4) runs continuing the opening in the bottom, and the side
of which has a rotationally symmetric recess (5) that extends transversely
through the channel (4); and a rotatable closure body (6), which is fitted in
the recess (5) and has a transversal hole (7) at the depth of the channel (4),
the hole (7) closing or opening the channel (4) when the closure body (6) is
rotated, characterized in that the end (8) of the closure body (6) is hinged
to the bottom (9) of the recess (5) and that the contact surface between the
closure body (6) and the recess (5) is rotationally symmetric and smaller
than the rotation surface of the recess (5).
2. A cock arrangement according to Claim 1, characterized in that the contact
surface is shaped like a truncated cone that expands from the bottom (9) of
the recess (5) to its outer edge (10).
3. A cock arrangement according to Claim 2, characterized in that the contact
surface is from 10 to 80%, preferably from 20 to 70% of the rotation sur-
face.
4. A cock arrangement according to any of Claims 1 to 3, characterized in
that the contact surface is in an area that begins from the bottom (9) and
ends in a point (11) in the recess (5), which is between the channel (4) and
the outer edge (10) of the recess (5), preferably closer to the channel (4)
than to the outer edge (10).
5. A cock arrangement according to Claim 5, characterized in that the recess
(5) and the closure body (6) have different radii of rotation outside the said
area (9-11).
6. A cock arrangement according to Claim 6, characterized in that the radius
of rotation of the closure body (6) decreases with respect to the radius of ro-
tation of the recess (5).

Description

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CLOSURE OF THE DISCHARGE CHANNEL OF A METAL CASTING VESSEL
The invention relates to a cock arrangement that is fitted in the bottom of a
metal
casting vessel provided with an opening, consisting of a channel body, through
which a channel runs, continuing the bottom opening, and the side of which is
pro-
vided with a rotationally symmetrical recess extending transversely through
the
channel, and of a rotatable closure body, which is fitted in the recess and
which
comprises a transverse hole at the depth of the channel, which hole closes or
opens the channel when the closure body is rotated.
Previously, for a closure of the casting conduit that starts from the bottom
of a mol-
ten metal-containing casting vessel, a plug was used, which was raised and low-
ered and which was coupled to a lifting rod extending over the surface of
molten
metal. One difficulty was to make the plug catch the casting hole, when the
conduit
was closed after lowering the molten metal. Furthermore, the plug wore quickly
in
use.
Because of these problems, the plugs of casting holes have later on been re-
placed with sliding closure units, as described in the published patent
application
FI 92022, among others. The sliding closure unit consists of a horizontal
plate that
is rotated around a vertical axis and located against the lower end of a
vertical
casting conduit, the plate comprising an opening, which can be brought next to
the
end of the conduit, whereby the conduit is open, and which can be rotated
aside
from the conduit, whereby the conduit is closed. The plate that forms the
sliding
closure unit is supported by a large frame, through which the rotating of the
plate
takes place. Such an arrangement is difficult to manufacture, cumbersome and
unreliable in use.
Closing valve-type solutions similar to the invention have also been
suggested.
These are known from publications GB 183 241 (Figs. 1 and 2), US 4 905 876
(Fig. 5), US 4 913 324 (Figs. 1 and 4) and US 4 557 462 (Fig. 3), among
others.
However, their problem is that they do not function at high temperatures.
Thus, US
4 557 462 suggests the use of a closing valve mainly for running light alloys
that
are easy to melt.
The purpose of the invention is to provide a cock arrangement, which is fitted
in
the bottom of a metal casting vessel containing an opening, and which does not
have the disadvantages of the closures mentioned above but which also
functions
well at the high temperatures required by metal casting.

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As mentioned above, the cock arrangement according to the invention consists
of
a channel body, through which the channel that continues the bottom opening of
the metal casting vessel runs, and the side of which has a rotationally
symmetrical
recess that extends transversely through the channel. A rotatable closure body
is
fitted in the recess, comprising a transversal hole at the depth of the said
channel
which can be turned in the same or another direction with respect to the
channel to
open and close the cock. The improvement of the cock arrangement is achieved
so that the end of the closure body is hinged to the bottom of the recess and
the
contact surface between the closure body and the recess is rotationally
symmetri-
cal and smaller than the rotation surface of the recess.
The concept "hinged" means that the end of the closure body is fitted in the
bottom
of the recess so that when rotated, the closure body otherwise remains
essentially
in place. The contact surface between the closure body and the recess refers
to a
surface that has a contact between the outer surface of the closure body and
the
inner surface of the recess, when the end of the closure body is fitted in the
bottom
of the recess.
Thus, it has been recognized that a closing valve-type metal casting cock func-
tions well at high temperatures, if the hole of the closure body is kept in
alignment
with the discharge channel of the melt and its sealing surfaces are
symmetrical
and have small surface areas. The closure body is, for example, a cylinder or
a
cone, the end of which is hinged to the bottom of the recess of the channel
body,
the recess being identical in shape. The hole of the closure remains easily in
alignment with the channel of the channel body. When the hole is aligned with
the
channel in this way, a considerably smaller contact surface between the pin
and
the recess can be used compared with the rotation surface of the recess. Due
to
the small contact surface, heat transfer is under control and the temperature
of the
control devices will not increase excessively.
The sealing contact surface is preferably from 10 to 80%, most preferably from
20
to 70% of the rotation surface. The contact surface is typically located in an
area
that begins from the bottom and ends in a point in the recess that is between
the
channel and the outer edge of the recess.
In the point where the sealing contact surface ends, the radii of rotation of
the re-
cess and the closure body typically diverge, so that the radius of rotation of
the
closure decreases with respect to the radius of rotation of the recess, for
example.
The recess and the closure body are preferably shaped like a truncated cone so
that the contact surface therebetween is in the shape of a truncated cone that
ex-

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pands from the bottom of the recess to its outer edge. Typically, the conical
inner
surface of the recess continues from the bottom to the edge, whereas the
conical
outer surface of the closure body shortly after the hole by decreasing the
inclina-
tion of the conical surface, for example.
The rotational movement of the closure body of the cock arrangement according
to
the invention for opening and closing the channel can be provided by means of
a
shaft rod, which is joined to the closure body, and an actuator, such as a
hydraulic
motor, which rotates the rod through a lever arm.
Metals, which can be cast by the cock arrangement according to the invention,
include cast iron, steel, aluminium, zinc, gold and other precious metals.
The channel body and the closure body are suitably made of a refractory
ceramic
material, such as corundum or some other aluminium oxide-based mixture. The
closure body is preferably provided with a coating, such as boron nitride,
which
provides air tightness. In addition to their fire resistance, ceramic
materials are
characterized in their dimension stability that is due to a minor thermal
expansion,
enabling small tolerances in the dimensioning of the elements of the cock.
The surface coming into contact with the recess of the closure body is
preferably
lubricated before installation, whereby good tightness is achieved and it is
easy to
rotate the closure body.
In the following, the invention is described in detail with the aid of an
example and
with reference to the appended figure that presents a cock arrangement
according
to one embodiment of the invention.
Plate 1 is part of the bottom of the metal casting vessel that is provided
with an
opening, molten metal being provided above the plate. A cock arrangement 2 is
fitted thereto. The cock arrangement 2 comprises a channel body 3 that is like
a
mouth brick, and the molten metal coming from the hole of the plate 1 flows
through the channel 4 of the channel body. The side of the channel body 3 also
has a hollow recess 5 with the shape of a truncated cone, extending
transversally
through and past the channel 4.
The cock arrangement 2 also has a rotatable closure body 6, which is fitted in
the
said recess 5 and is, thus, partly of the same conical shape. The closure body
6
has a transversal hole 7 with respect to its length, its axis essentially
seizing or
joining the axis of the channel 4. The end 8 of the closure body 6 is hinged
to the
bottom 9 of the recess. In this way, the clearance of the closure body 6 and
the
recess 5 from the bottom all the way past the channel 4 and the hole 7 is
accurate

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and will not change according to the temperature, because the guiding surface
is
near the clearance at the same temperature.
The contact surface that seals the closure body 6 and the recess 5 extends
from
the bottom 9 of the recess 5 all the way past the channel 4 and the hole 7. It
ends
at the point 11 of the recess 5, which is between the channel 4 and the outer
edge
of the recess 5. It preferably ends closer to the channel 4 than to the outer
edge 10. The contact ends so that the inclination of the closure body 6
decreases
from the point 11 outwards. Thus, the outer surface of the closure body 6 does
not
remain in contact with the inner surface of the recess 5 in the outer area,
wherein
10 the temperatures of the surfaces differ from one another to a larger
extent.
It is obvious to those skilled in the art that various applications of the
invention are
not limited to the example presented above but can vary within the appended
claims. For example, it is possible to place several superimposed mouth bricks
under the casting vessel, together forming the discharge channel for the
molten
metal.
An improvement to the bottom cock of a metal casting vessel is synergistically
pro-
vided by the above combination, wherein the end of the closure body is hinged
to
the bottom of the recess and, at the same time, the rotational contact surface
is
radically reduced. The new solution provides a better result than the previous
clos-
ing valves and sliding closure units.