U.S. patent application number 10/597076 was filed with the patent office on 2007-06-21 for elongated stopper device.
This patent application is currently assigned to REFRACTORY INTELLECTUAL PROPERTY GMBH & CO. KG. Invention is credited to Wilhelm Janko, Stephen Lee, Franz Reiterer.
Application Number | 20070138715 10/597076 |
Document ID | / |
Family ID | 34925981 |
Filed Date | 2007-06-21 |
United States Patent
Application |
20070138715 |
Kind Code |
A1 |
Lee; Stephen ; et
al. |
June 21, 2007 |
Elongated stopper device
Abstract
The invention relates to an elongated stopper device for flow
control of molten metal, i.e., for controlling the flow of molten
metal from a metallurgical vessel, such as a tundish.
Inventors: |
Lee; Stephen; (Cardross,
GB) ; Reiterer; Franz; (Leoben, AT) ; Janko;
Wilhelm; (Graz, AT) |
Correspondence
Address: |
WALKER & JOCKE, L.P.A.
231 SOUTH BROADWAY STREET
MEDINA
OH
44256
US
|
Assignee: |
REFRACTORY INTELLECTUAL PROPERTY
GMBH & CO. KG
11, Wienerbergstrasse
Wien
AT
A-1100
|
Family ID: |
34925981 |
Appl. No.: |
10/597076 |
Filed: |
July 9, 2005 |
PCT Filed: |
July 9, 2005 |
PCT NO: |
PCT/EP05/07470 |
371 Date: |
July 11, 2006 |
Current U.S.
Class: |
266/272 |
Current CPC
Class: |
B22D 41/18 20130101 |
Class at
Publication: |
266/272 |
International
Class: |
C21C 5/48 20060101
C21C005/48 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 29, 2004 |
EP |
04017978.0 |
Claims
1. An elongated stopper device for flow-control of molten metal
from a vessel, containing molten metal, said device comprising: a)
a body (10) made of a refractory ceramic material, b) a bore hole
(12), having a longitudinal axis (A) and extending from an upper
surface (10u) of said body downwardly, c) said bore hole (12) being
equipped along its length with at least one anchor (16) of a
different material, fixed within said body (10) between the upper
surface (10u) of said body (10) and a lower end of said bore hole
(12) and projecting radially into said bore hole with its main
surfaces (16u, 16l) running predominantly perpendicular to the
longitudinal axis (A) of the bore hole (12), d) said anchor (16)
being adapted to receive and fix one threaded end (14l) of a metal
rod (14), inserted into said bore hole (12).
2. Stopper device according to claim 1, wherein said metal rod (14)
has an at least partially threaded section (14l) at its inserted
end.
3. Stopper device according to claim 1, including a sealing member
(18) being arranged adjacent to said anchor (16).
4. Stopper device according to claim 3, wherein said sealing member
(18) being arranged along a circumferential wall (12u) of said bore
hole (12) below said part (16), extending radially into said bore
hole and longitudinally along a certain length (L) of said bore
hole (12) and adapted to receive said rod (14) in a threadably
manner.
5. Stopper device according to claim 3, wherein said sealing member
(18) has a cylindrical shape.
6. Stopper device according to claim 3, wherein that part of the
bore hole (12) receiving the sealing member (18) is conically
designed with its smaller part at its lower end.
7. Stopper device according to claim 3, wherein said rod (14) has a
smaller width at its part which first enters said sealing member
(18) than at its part on top.
8. Stopper device according to claim 3, wherein said sealing member
(18) is made of graphite.
9. Stopper device according to claim 1, wherein said anchor (16)
has a sheet like shape with its main surfaces (16u, 16l) running
predominantly perpendicular to the longitudinal axis (A) of the
bore hole (12).
10. Stopper device according to claim 1, wherein said anchor (16)
is made of at least two sheets each designed like a ring section
and arranged at a distance to each other along an imaginary helical
line.
11. Stopper device according to claim 1, wherein said anchor (16)
is made of three sheets each designed like a ring section and
arranged at equal distances to each other along an imaginary
helical line.
12. Stopper device according to claim 1, wherein said anchor (16)
is a snap ring.
13. Stopper device according to claim 12, wherein said snap ring
encircles more than 180.degree..
14. Stopper device according to claim 12, wherein said snap ring
encircles less than 360.degree..
15. Stopper device according to claim 12, wherein said snap ring
encircles 360.degree..
16. Stopper device according to claim 12, wherein said snap ring
encircles more than 360.degree..
17. Stopper device according to claim 12, wherein said snap ring
encircles less than 450.degree.
18. Stopper device according to claim 1, wherein said anchor (16)
is made of metal.
19. Stopper device according to claim 1, wherein said rod (14) has
an axial bore (14c).
20. Stopper device according to claim 1, wherein the anchor(s) (16)
are arranged at an angle .alpha. of between 1 and 5.degree. with
respect to a plane perpendicular to the longitudinal axis (A) of
the bore hole (12).
Description
[0001] The invention relates to an elongated stopper device for
flow control of molten metal, i.e. for controlling the flow of
molten metal from a metallurgical vessel, such as a tundish.
[0002] It is well known in steel casting to employ a one-piece
refractory stopper rod, which is moved vertically by the use of a
lifting mechanism in order to vary the cross-sectional area of an
outlet opening of the corresponding metallurgical vessel.
[0003] Those stopper rods have also been used to introduce an inert
gas, such as argon, into the molten steel for removing non-metallic
inclusions from the molten metal.
[0004] In all cases the stopper device must withstand hours
submerged in molten metal. It must also be capable of enduring the
harsh thermal shock encountered on the start-up of casting and any
mechanical forces imposed to it.
[0005] Insofar many attempts have been made to improve the
mechanical and thermal properties of such a stopper device and to
improve its behaviour during use.
[0006] EP 0 358 535 B2 discloses a one-piece refractory stopper rod
adapted to a lifting mechanism, comprising an elongated stopper rod
body of a refractory material, which body being provided with a
bore hole, having a longitudinal axis and extending from an upper
surface of said body downwardly. Within said axial bore hole a
metal bushing is inserted to threadably receive a threaded part of
a metal rod, inserted in said refractory body for attachment to a
corresponding lifting mechanism.
[0007] One problem with such device is the anchorage of said metal
bushing with the refractory material of the body and the
requirement to avoid differential stresses between the ceramic body
and the metal bushing insert, which can cause mechanical breakage
of the ceramic material during service operation.
[0008] According to DE 198 23 990 C2 a stopper device is disclosed,
providing an upper part of the bore hole embodying a ceramic
insert. This insert provides an inner thread, corresponding to an
outer thread of a corresponding metal rod threadably fixed within
said insert after insertion of the rod into said threaded insert.
Whilst the use of two ceramic materials reduces the risk of
differential stresses between the body material and the holding
insert problems remain associated with the difficulty in
maintaining an accurate threadform in a high strength ceramic
material at an acceptable cost.
[0009] It is therefore an object of the present invention to
provide an elongated stopper device for flow control of a molten
metal from a vessel, containing molten metal, which is easy to
produce and provides simple fixing means for attachment of a
corresponding metal rod within a corresponding refractory ceramic
body.
[0010] It has now been found that such attachment of the metal rod
within a corresponding bore hole of the refractory ceramic body may
be achieved with much simpler means than a cylindrical metal
bushing or an elongated cylindrical ceramic insert, namely by at
least one anchor such as a sheet like part of a different material
(compared with the material of the body), whereby said anchor is
fixed within said body between the upper surface of said body and a
lower end of the corresponding bore hole and protrudes radially
into said bore hole with its main surfaces running predominantly
perpendicular to the longitudinal axis of the bore hole within the
upper part of the body.
[0011] Contrary to prior art constructions, which disclose fixing
means for the metallic rod, said known fixing means all extending
along a significant length of the longitudinal axis of the
elongated refractory body, the invention provides a fixing means
arranged predominantly perpendicular to the longitudinal axis of
said body and/or said bore hole respectively and at a specific
position along the length of the bore within said body. Insofar
these fixing means are much smaller than a bushing, i.e. much less
different material is introduced into the ceramic body and much
less thermal and mechanical stresses between fixing means (anchor)
and ceramic body are to be expected.
[0012] In other words: The said anchor is arranged at a specific
height of said elongated stopper device at a distance to its upper
surface and at a distance to its lower end. Typically it is
arranged at a place between 10 and 40% of the total length of the
stopper device, calculated from the upper end of the refractory
body, which may be 5-25 cm, typically about 10 cm from the upper
end.
[0013] Obviously such a generally radial fixing means presents a
significantly reduced axial length than any insert or bushing
extending along the longitudinal axis of a stopper. Any mechanical
stresses generated in the ceramic body by the longitudinal thermal
expansion effects arising from said generally radial fixing means
are therefore much lower than those generated with prior art
constructions.
[0014] Further it may easily be fixed within the ceramic refractory
surroundings (refractory body material), for example during
isostatic pressing of said stopper device.
[0015] The manufacturing may be done as follows: The aforementioned
anchor(s), for example sheet like part(s) is (are) placed with
their end portion located into corresponding slits of a suitable
mandrel (core rod). A rubber outer mould is placed over the mandrel
assembly and a refractory ceramic material is filled into the
cylindrical space between the mandrel and mould. Thereafter the
mould containing the refractory material, including the fixing
means, is isostatically pressed. The outer mould is then removed
and the mandrel, made of at least two longitudinally running parts,
is removed from the compacted product leaving the outer portion(s)
of the anchor(s) (sheet like parts) firmly embedded in the ceramic
body with their inner extremity(ies) projecting into predetermined
position(s) within the ceramic bore.
[0016] During said manufacturing a sealing member may further be
placed within said mould, as will be described later.
[0017] In its most general embodiment the invention relates to an
elongated stopper device for flow-control of molten metal from a
vessel, containing molten metal, said device comprising: [0018] a
body made of a refractory ceramic material, [0019] a bore hole,
having a longitudinal axis and extending from an upper surface of
said body downwardly, [0020] said bore hole being equipped along
its length with at least one anchor of a different material, fixed
within said body between the upper surface of said body and a lower
end of said bore hole and projection radially into said bore hole
with its main surfaces running predominantly perpendicular to the
longitudinal axis of the bore hole, [0021] said anchor being
adapted to receive and fix one threaded end of a metal rod,
inserted into said bore hole.
[0022] According to an embodiment said metal rod has an at least
partially threaded section at its inserted end. This threaded
section serves, together with the anchor (fixing means) for
attachment of said metal rod within said bore hole of said
refractory body.
[0023] It will be sufficient to achieve said attachment by
providing just one anchor, like a sheet like part, projecting
radially into said bore hole. During insertion of the rod into the
bore hole the threaded section of the rod will run along said
fixing part and provide the necessary attachment of said rod within
said body.
[0024] Obviously this fixing (anchoring) means should best have a
certain circumferential length. It may extend over 20 to
.ltoreq.360.degree. of the inner wall of said bore hole or even a
bit more.
[0025] Especially in cases where it extends over more than
20.degree. it will be advantageous to arrange said sheet like part
with a certain declination (descending gradient or slope) with
respect to the longitudinal axis of the bore hole, but not
necessary to achieve the desired locking.
[0026] This is especially true if the anchor (sheet like part) is
more or less ring shaped, i.e. running in the circumferential
direction around the inner bore hole surface for more than
180.degree., especially more than 270.degree. C. and it must be
sloped when this part has a length of more than 360.degree.. A snap
ring design is one further possibility.
[0027] While said anchor may be designed as a ring, for example
with a circumferential length between 270.degree. and
.ltoreq.360.degree. or up to 450.degree. or 300.degree. to
400.degree. it is also possible to prepare said fixing means by at
least two anchors, each designed like a ring section and arranged
at a distance to each other along an imaginary helical line. A
further embodiment provides fixing means made of three anchors,
each designed like a ring section and arranged at equal distances
to each other along an imaginary helical line. Even two or three
radially arranged pins, spaced to each other, may provide the
necessary anchoring means for securing and holding the rod within
the body. The anchor(s) may also be arranged along a plane,
perpendicular to the longitudinal axis of the rod.
[0028] It becomes clear from the explanation above that a one piece
fixing means is the most convenient way for an easy production of
said stopper device.
[0029] Said fixing means may be made of any material, different
from the material of the refractory body and strong enough to
threadably receive the threaded part of the corresponding metal
rod. For example the fixing means may be made of metal or special
ceramics like silicon nitride, zirconia or alumina.
[0030] As explained above a sealing member may be arranged along
said bore hole and best adjacent to said fixing means.
[0031] This improves the tightness between the ceramic body and the
metal rod, especially in cases where said stopper rod is used for
introducing a gas into a metallurgical melt.
[0032] A corresponding sealing member (gasket) may be placed upon a
corresponding annular sealing surface, provided at a certain height
of the bore hole. This construction is further disclosed in EP 1
135 227 B1, the disclosure of which is insofar referred to
here.
[0033] Said sealing means may also be arranged along a
circumferential wall of said bore hole below or above said fixing
part and extending radially into said bore hole and longitudinally
along a certain length of said bore hole and adapted to receive
said rod in a threadably manner.
[0034] Insofar as in this description reference is made to "above",
"upper", "lower", "downwardly", etc it is referred to the typical
use of such stopper rod, running predominantly vertical.
[0035] As described above a sheet like part used for attachment of
the corresponding rod is arranged along a defined longitudinal
position of the body. Therefore, when introducing the rod, the
corresponding outer thread of said rod will protrude downwardly
over said fixing means. This protruding part of the threaded rod
section is now used to provide an effective sealing as it will be
engraved into said gasket. The material of the gasket, withstanding
high temperatures, thereby penetrates into the threads and causes a
very effective sealing and tightness over the corresponding lengths
of said sealing and said rod respectively.
[0036] Said sealing member may have a cylindrical shape. It should
protrude into the bore hole.
[0037] That part of the bore hole, receiving the sealing member,
may be conically designed with its smaller part at its lower
end.
[0038] The rod may then have a smaller width at its part adjacent
to said sealing member compared with its part on top.
[0039] The sealing member may be made of any material withstanding
high temperatures as may be present during use of stopper device.
Graphite is one of those materials. A possible material is a
compressed graphite material with a purity >95 weight-% carbon
and a density of approximately 1,4 g/cm.sup.3. The seal may have
the form of a preformed component which can be either inserted into
the stopper body immediately prior to the installation of the steel
support rod or co-formed with the ceramic body of the stopper rod
during the production process.
[0040] Alternatively the seal may be created during the fabrication
process of the stopper by compression of a graphite element
comprising either exfoliated graphite powder or a coil of a
graphite foil, placed around the forming tool (mould) and then
surrounded by the ceramic body material of the stopper during the
mould filling process.
[0041] It seems clear from the description above that if said
stopper device is used for introducing gas the corresponding rod
will be equipped with an axial bore through which the gas is fed.
The corresponding bore hole of the body will then be provided with
at least one opening at its lower end.
[0042] Further details of the invention will be described in the
subclaims and the other application documents.
[0043] The invention will now be described with respect to one
embodiment which in no way limits the scope of the claimed stopper
device.
[0044] The only FIGURE shows schematically an upper part of a
stopper device in a partly longitudinal cross sectional view.
[0045] The stopper device comprises an elongated refractory body 10
with a central bore hole 12, positioned coaxially with respect to
body 10 and adapted to receive fixedly a metal rod 14 for its
attachment to a (non-shown) lifting mechanism.
[0046] The bore hole 12 is of more or less cylindrical shape and is
running from an upper surface 10u of the body 10 downwardly (arrow
D) and terminating in a (non-shown) opening at a lower end of said
body 10.
[0047] At a distance d from upper surface 10u a sheet like metal
ring 16 is integrated in the refractory material of body 10. Said
ring projects radially into said bore hole 12. Main surfaces (upper
surface 16u; lower surface 16l) are running predominantly
perpendicular to a longitudinal axis A of said bore hole 12.
[0048] In the FIGURE said flat ring 16 is arranged such that is
provides an angle .alpha. of ca. 3 degrees to a horizontal plane
(perpendicular to longitudinal axis A). This angle may be adapted
to match the pitch of the threadform on the metal rod 14. Said ring
16 is not closed but slit and encircles an angle of about
330.degree.. Free ends of said ring are offset in the longitudinal
direction of bore hole 12.
[0049] This sheet like ring 16, serving as a fixing means for said
rod 14, which will be described later, has been co-pressed with
body 10. It protrudes (projects) into bore hole 12 over a certain
width so as to threadably receive an outer thread 14t (symbolized
by dots) of a lower part 14l of metal rod 14, which may have a
central, longitudinal through passage 14c (symbolized by
lines).
[0050] During assembling said metal rod 14 is introduced into bore
hole 12, thereby turned, so that the outer thread 14t of rod 14
engages the protruding part 16p of ring 16.
[0051] Rod 14 is then further introduced into bore hole 12
(downwardly, arrow D) and then engages a cylindrical graphite
gasket 18, arranged over a length L in front of an inner wall 12w
of bore hole 12.
[0052] During said further introduction of rod 14 into bore hole 12
the gasket material penetrates into spaces of thread 14t, thereby
providing intimate sealing between body 10 and rod 14 all over
length L.
[0053] According to the FIGURE the final position of rod 14 within
bore hole 12 is characterized by a small projection of threaded end
14e past the end of sealing member 18. Alternatively the threaded
rod could finish within the length of the sealing element.
[0054] Upper surface 10u of body 10 butts on blocking means 20, 22
located fixedly on metal rod 14 so that rod 14 may not lengthen
opposite to arrow D. Blocking means 20, 22 have a nut-like shape
and are prepared with inner threads, corresponding to thread 14t of
rod 14.
[0055] The limited size of said sheet like fixing means (slit ring
16) and its mostly horizontal (radial) arrangement with respect to
the elongated stopper design guarantees safe fixation of rod 14 in
bore hole 12 even when under high thermal load said metallic fixing
means and said metallic rod will expand equally in a radial
direction, with little or no differential expansion in the axial
direction.
[0056] Together with the downwardly following sealing gasket the
described design leads to an improved stopper device which may be
used for different purposes, i.a. for feeding a gas along channel
14c and bore hole 12 into a metal melt. The intimate contact
between gasket 18 and outer thread 14t of rod 14 are further
responsible for the radial compression of the sealing element and
improved tightness of said device. The expansion of the metallic
rod at service temperature serves to further increase the sealing
efficiency by maintaining compressive forces on the seal.
[0057] In the longitudinal direction the fixing means should be as
small as possible. It may have a "thickness" of .ltoreq.5 mm,
.ltoreq.3 mm, .ltoreq.2 mm or even .ltoreq.1 mm, while the "length"
(L) of said sealing means may be .gtoreq.10 mm, .gtoreq.20 mm,
.gtoreq.30 mm or .gtoreq.40 mm.
[0058] The invention includes embodiments with two or more fixing
means at different positions along the longitudinal axis of the
elongated stopper rod, i.e. the respective fixing means have a
distance to each other (in the longitudinal direction of the bore
hole). The distance may be in the range of a few cm or more. These
distinct fixing means may coact with one or more outer threads of
the metallic rod.
* * * * *