U.S. patent application number 09/917797 was filed with the patent office on 2002-01-31 for tundish impact pad.
Invention is credited to Clark, Michael Robert.
Application Number | 20020011696 09/917797 |
Document ID | / |
Family ID | 10848189 |
Filed Date | 2002-01-31 |
United States Patent
Application |
20020011696 |
Kind Code |
A1 |
Clark, Michael Robert |
January 31, 2002 |
Tundish impact pad
Abstract
A tundish impact pad formed from refractory material is
disclosed, the impact pad comprising a base having an impact
surface which in use faces upwardly to receive molten metal, e.g.
steel, poured onto the impact pad, and a sidewall extending
upwardly from at least part of the periphery of the impact surface.
At least part of the interior, and a surface, of the sidewall are
porous and the impact pad includes means for supplying a gas, e.g.
argon, to the porous interior of the sidewall, to enable the gas to
be supplied to the molten metal from the porous surface of the
sidewall. The tundish impact pad may be used during the continuous
casting of steel.
Inventors: |
Clark, Michael Robert;
(Stourbridge, GB) |
Correspondence
Address: |
NIXON & VANDERHYE P.C.
8th Floor
1100 North Glebe Road
Arlington
VA
22201
US
|
Family ID: |
10848189 |
Appl. No.: |
09/917797 |
Filed: |
July 31, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09917797 |
Jul 31, 2001 |
|
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PCT/GB00/00518 |
Feb 17, 2000 |
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Current U.S.
Class: |
266/275 |
Current CPC
Class: |
B22D 41/003 20130101;
B22D 1/005 20130101 |
Class at
Publication: |
266/275 |
International
Class: |
C21B 003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 22, 1999 |
GB |
9903937.2 |
Claims
1. A tundish impact pad formed from refractory material, the impact
pad comprising a base having an impact surface which in use faces
upwardly to receive molten metal poured onto the impact pad, and a
sidewall extending upwardly from at least part of the periphery of
the impact surface, characterised in that at least part of the
interior, and a surface, of the sidewall are porous and the impact
pad includes means for supplying a gas to the porous interior of
the sidewall, to enable the gas to be supplied to the molten metal
from the porous surface of the sidewall.
2. A kit of parts for assembly to form a tundish impact pad,
comprising: (a) a base part formed from refractory material and
having an impact surface for receiving molten metal poured onto the
impact pad in use; and (b) a peripheral sidewall part formed from
refractory material, for attachment directly or indirectly to the
base part to form at least part of a sidewall around at least part
of the periphery of the impact surface; characterised in that at
least part of the interior, and a surface, of the sidewall part are
porous, and the base part and/or the sidewall part include(s) means
for supplying a gas to the porous interior of the sidewall part, to
enable the gas to be supplied to the molten metal from the porous
surface of the sidewall part.
3. A tundish for containing molten metal, the tundish comprising a
floor and sidewalls formed from refractory material, and further
comprising an outlet for the molten metal, characterised in that
the tundish contains an impact pad according to claim 1 or an
impact pad assembled from a kit according to claim 2, placed on the
floor of the tundish.
4. A method of removing inclusions from molten metal in a tundish,
by means of a tundish impact pad according to claim 1 or an impact
pad assembled from a kit according to claim 2, the method
comprising supplying a gas to the molten metal from the porous
sidewall of the impact pad.
5. An impact pad, kit, tundish or method according to any preceding
claim, in which the sidewall is porous in only an upper portion
thereof.
6. An impact pad, kit, tundish or method according to any preceding
claim, in which at least part of an upper surface of the sidewall
is porous.
7. An impact pad, kit, tundish or method according to any preceding
claim, in which the sidewall includes an inwardly projecting
ledge.
8. An impact pad, kit, tundish or method according to claim 7, in
which at least part of the porosity of the sidewall comprises at
least part of the ledge.
9. An impact pad, kit, tundish or method according to any preceding
claim, in which the means for supplying a gas to the interior of
the sidewall comprises one or more conduits.
10. An impact pad, kit, tundish or method according to claim 9, in
which the or each conduit is perforated along at least part of its
length.
11. An impact pad, kit, tundish or method according to any
preceding claim, in which the gas is an inert gas, preferably
argon.
12. An impact pad, kit, tundish or method according to any
preceding claim except claim 1 or claim 2, in which the tundish
includes one or more gas supply conduits for supplying the gas to
the impact pad.
13. An impact pad, kit, tundish or method according to claim 12
when dependent upon claim 9 or claim 10, in which at least one
conduit in the tundish is connected to a respective conduit in the
impact pad.
Description
[0001] This invention relates to the handling of molten metal,
especially steel. In particular, the invention relates to a tundish
impact pad, i.e. an article formed from refractory material to be
placed on the floor of a tundish to receive an incoming stream of
molten metal poured into the tundish from a ladle. The invention
has particular utility in the continuous casting of steel.
[0002] International Patent Application No. WO 96/14951 (FOSECO)
discloses a tundish impact pad comprising a body of refractory
material capable of withstanding contact with molten steel in a
tundish. The impact pad body comprises a base having an impact
surface, an outer sidewall extending upwardly from the impact
surface, and a top surface connected to the sidewall and defining
an opening therein. The top surface has an inner annular portion
substantially parallel to the impact surface, and there is a
substantially right angled corner between the sidewall and the
impact surface, and also between the sidewall and the inner annular
portion of the top surface.
[0003] U.S. Pat. No. 4,468,012 discloses a device for removing
inclusions from a molten metal which is poured into a casting
tundish. The device comprises long blocks of heat-insulating
material which is sinterable at the temperature of the molten metal
and which comprises inorganic particles incorporated in an organic
binder which is decomposable at the temperature of the molten metal
so as to form pores in the heat-insulating material. A duct extends
through each long block, for the supply of an inert gas which
diffuses into the molten metal through the pores in the
heat-insulating material.
[0004] U.S. Pat. No. 5,054,749 discloses a tundish for the
continuous casting of steel, comprising a permanent refractory cast
on a sheet metal frame defining an external wall of the tundish. In
the bottom of the tundish there is a gas chamber and a porous
refractory wear plate surmounting and extending over the chamber. A
gas inlet duct extends from an upper edge of the tundish and down
through the permanent refractory to the gas distribution
chamber.
[0005] United Kingdom Patent Application No. 2164281A discloses a
tundish used in a steel making process, which includes a
replaceable refractory lining disposed on the inner surface of the
bottom and side walls of the tundish. A porous refractory tile is
supported upon the upper surface of the refractory lining and has a
major axis extending substantially the entire width of the tundish.
The porous tile encapsulates a perforated conduit for supplying
inert gas which is allowed to emanate from the tile across the
width of the tundish, to remove unwanted inclusions from the steel.
The tile has a ramp-like surface for deflecting steel flowing
towards it upwardly in the tundish. The tundish also includes an
impact pad upstream of the tile.
[0006] According to a first aspect, the present invention provides
a tundish impact pad formed from refractory material, the impact
pad comprising a base having an impact surface which in use faces
upwardly to receive molten metal poured onto the impact pad, and a
sidewall extending upwardly from at least part of the periphery of
the impact surface, characterised in that at least part of the
interior, and a surface, of the sidewall are porous, and the impact
pad includes means for supplying a gas to the porous interior of
the sidewall, to enable the gas to be supplied to the molten metal
from the porous surface of the sidewall.
[0007] According to a second aspect, the invention provides a kit
of parts for assembly to form a tundish impact pad, comprising:
[0008] (a) a base part formed from refractory material and having
an impact surface for receiving molten metal poured onto the impact
pad in use; and
[0009] (b) a peripheral sidewall part formed from refractory
material, for attachment directly or indirectly to the base part to
form at least part of a sidewall around at least part of the
periphery of the impact surface; characterised in that at least
part of the interior, and a surface, of the sidewall part are
porous, and the base part and/or the sidewall part include(s) means
for supplying a gas to the porous interior of the sidewall part, to
enable gas to be supplied to the molten metal from the porous
surface of the sidewall part.
[0010] According to a third aspect, the invention provides a
tundish for containing molten metal, the tundish comprising a floor
and sidewalls formed from refractory material, and further
comprising an outlet for the molten metal, characterised in that
the tundish contains an impact pad according to the first aspect of
the invention or assembled from a kit of parts according to the
second aspect of the invention, placed on the floor of the
tundish.
[0011] The gas is preferably an inert gas, e.g. argon or nitrogen,
and is preferably supplied to the molten metal for the purpose of
removing unwanted inclusions from the metal.
[0012] According to a fourth aspect, the invention provides a
method of removing inclusions from molten metal in a tundish, by
means of tundish impact pad according to the first aspect of the
invention or assembled from a kit of parts according to the second
aspect of the invention, the method comprising supplying a gas to
the molten metal from the porous sidewall of the impact pad.
[0013] The expression "porous" is intended to include any
arrangement in which at least part of the sidewall is able to
supply gas to the molten metal from the interior of the sidewall.
For example, pores, channels or other apertures in the sidewall may
generally have any shape, for example they may be generally round,
or elongate, in cross-section, thus appearing in the form of round
holes or slits, respectively, on the surface of the sidewall.
Furthermore, the porosity of the sidewall may be in the form of an
irregular network of pores, or it may be in the form of a
substantially regular structure of channels, for example.
[0014] The invention has the advantage that because the gas is
supplied to the molten metal in the tundish from the sidewall of
the impact pad, it may provide a kind of "curtain" of gas bubbles
surrounding the impact surface of the pad (or at least part of the
impact surface). This means that molten metal poured into, and
subsequently flowing out of, the impact pad will normally flow
through the gas curtain, and furthermore the gas will come into
contact with the molten metal very soon after the metal has been
poured into the tundish. The gas therefore has substantially the
longest possible contact time with the molten metal, and will
generally be carried with the metal as it flows away from the
impact pad. This generally leads to a more efficient incorporation
of the gas into the metal, and therefore a more efficient removal
of unwanted inclusions, for example.
[0015] In some preferred embodiments of the invention, the sidewall
of the impact pad is porous at least in an upper portion thereof.
Preferably, at least part of an upper surface of the sidewall is
porous.
[0016] The sidewall may include an inwardly projecting ledge, which
is preferably located substantially at the top of the sidewall (but
which may, alternatively, project from the side of the sidewall).
By "inwardly projecting" is meant projecting over at least part of
the impact surface of the impact pad. At least a central region of
the impact surface is preferably substantially planar, and
substantially horizontal in use. In such embodiments, the ledge is
preferably substantially parallel to the planar region of the
impact surface.
[0017] For embodiments of the invention which include an inwardly
projecting ledge, at least part of the porosity of the sidewall may
advantageously comprise at least part of the ledge, and preferably
at least an upper surface thereof. For example, substantially the
entire upper surface of the sidewall, including the upper surface
of an inwardly projecting ledge, may be porous. The inwardly
projecting ledge may, for example, comprise an upper portion which
is porous and a lower portion which is substantially non-porous.
Alternatively, the ledge may comprise upper and lower porous
portions and a substantially non-porous intermediate portion.
[0018] Additionally or alternatively, at least part of the porosity
of the sidewall may be provided by a portion of the sidewall
located between the base and an upper portion of the sidewall (e.g.
a ledge)--i.e. the main body of the sidewall may provide at least
part of the porosity of the sidewall. At least part of the inner
and/or outer surface(s) of the sidewall may be porous, and
therefore supply gas to the molten metal in use.
[0019] As mentioned above, the second aspect of the invention is a
kit of parts for assembly to form a tundish impact pad. When
reference is made in this specification to the base or sidewall of
the impact pad according to the first aspect of the invention, it
is to be understood that the reference also applies to the base
part or sidewall part, respectively, of the kit of parts.
Furthermore, as mentioned above, in some preferred embodiments of
the impact pad, the sidewall includes an inwardly projecting ledge.
When such embodiments of the impact pad are provided as a kit of
parts, in accordance with the second aspect of the invention, the
inwardly projecting ledge may comprise an integral part of the
sidewall part, or it may comprise a further separate part, i.e. a
further sidewall part of the kit.
[0020] The means for supplying a gas to the interior of the
sidewall preferably comprises one or more conduits. The term
"conduit" is intended to include "pipe", "channel", "duct" and the
like. The or each conduit is preferably perforated along at least
part of its length, in order to release the gas. The gas is
therefore preferably supplied to substantially the entire porous
region or regions of the sidewall (or the entire sidewall for
embodiments in which the entire sidewall is porous). The impact pad
therefore preferably includes one or more conduits (e.g. a network
of conduits) for supplying the gas to the porous sidewall. For
embodiments of the invention in which the sidewall extends around
the entire periphery of the impact surface, the sidewall preferably
includes at least one gas supply conduit extending through the
entire length thereof (e.g. an endless conduit).
[0021] The tundish preferably includes one or more gas supply
conduits for supplying the gas to the impact pad. In use, at least
one conduit in the tundish is preferably connected to a respective
conduit in the impact pad. The connection between a tundish gas
supply conduit and an impact pad conduit may, for example, be made
at the base of the impact pad, or at the sidewall of the impact
pad, depending upon the design of the tundish and the arrangement
of the impact pad within the tundish. For arrangements in which
part of the sidewall of the impact pad is located adjacent to a
sidewall of the tundish, the conduit connection may conveniently be
made at the impact pad sidewall for example, whereas for
arrangements in which the impact pad is located a distance from the
sides of the tundish, it may be more convenient for the conduit
connection to be made at the base of the impact pad. In the latter
case, the conduit connection may be underneath the base of the
impact pad, but it is generally preferred for the connection to be
made at a side of the base of the impact pad, the tundish conduit
for example lying on the floor of the tundish and provided in a
refractory block or under a refractory cover. The tundish
conduit(s) is/are preferably connected to a gas source located to
the exterior of the tundish.
[0022] The invention will now be described, by way of example, with
reference to the accompanying drawings, of which:
[0023] FIG. 1 is a schematic illustration in cross section of a
one-piece impact pad according to the invention;
[0024] FIG. 2 is a schematic illustration in cross section of a
two-piece impact pad according to the invention;
[0025] FIG. 3 is a schematic illustration in cross section of a
three piece impact pad according to the invention; and
[0026] FIG. 4 is a schematic illustration in cross section of a
tundish containing an impact pad according to the invention.
[0027] FIG. 1 shows in cross-section a one-piece tundish impact pad
1 formed from concrete. The impact pad comprises a base 3 having an
upwardly facing impact surface 5 for receiving molten metal poured
onto the impact pad, and a sidewall 7 extending upwardly from the
periphery of the impact surface. The impact pad is generally square
or rectangular in plan view (but other shapes are of course
possible, e.g. other quadrilateral shapes, or round, e.g.
circular). An upper portion 9 of the sidewall 7 is formed from a
porous concrete material. In use, a gas supply conduit (not shown)
in the impact pad supplies a gas to the interior of the porous
portion 9, and the gas permeates through the porous portion and is
released as a "curtain" of gas bubbles emanating from the upper
surface of the sidewall of the impact pad. The sidewall includes an
inwardly projecting ledge 11, and part of the porous upper portion
9 of the sidewall comprises an upper part of this ledge.
[0028] FIG. 2 shows an impact pad similar to that shown in FIG. 1,
with a porous upper portion 9, but this impact pad has been
assembled from a kit of two main parts, namely a base part 13
comprising a base 3 and a lower region of sidewall 7, and a
sidewall part 15 which constitutes an upper region of the sidewall,
comprising the porous upper portion 9 and a non-porous portion 16.
The two parts of the kit have been assembled and cemented together
to form the impact pad.
[0029] FIG. 3 shows an impact pad similar to those shown in FIGS. 1
and 2, except that this impact pad has been assembled from a kit of
three main parts, and it contains an additional porous portion in
the sidewall. The kit comprised a base part 17, a lower sidewall
part 19, and an upper sidewall part 15 (which is the same as that
of FIG. 2), the parts having been assembled and cemented together
to form the complete impact pad. The lower sidewall part 19
comprises a porous portion 23, and the upper sidewall portion
comprises an upper porous portion 9 and a lower non-porous portion
16. The lower porous portion 23 releases the gas from its exterior
and interior surfaces, i.e. the gas is released both into the
interior of the tundish and to the exterior of the tundish. In
combination with the upper porous portion 9 which releases the gas
from the upper surface of the sidewall, the result is the
production of a (radially) deeper "curtain" of gas bubbles
surrounding the impact surface, compared to that produced by the
impact pads shown in FIGS. 1 and 2.
[0030] FIG. 4 shows, schematically and in cross-section, a tundish
25 filled with molten steel 27 and containing an impact pad 1
according to the invention. The flow direction of the molten steel
from a submerged entry shroud 29 onto the impact surface 5 of the
impact pad, through bubbles of gas supplied by the impact pad and
towards and through outlets 31 is indicated by the arrows. The gas
supply conduits are not shown.
* * * * *