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Patent 1036791 Summary

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(12) Patent: (11) CA 1036791
(21) Application Number: 1036791
(54) English Title: METHOD OF MANUFACTURING STEEL INGOTS OR CASTINGS
(54) French Title: METHODE DE FABRICATION DE LINGOTS OU DE PIECES COULEES EN ACIER
Status: Term Expired - Post Grant Beyond Limit
Bibliographic Data
Abstracts

English Abstract


ABSTRACT OF THE DISCLOSURE
According to the present invention, a method of
manufacturing cast metal bodies, for example moulded iron
metal or iron metal alloy castings or ingots, is characterized
in that instead of an anti piping agent, a reusable insulating
material, which prevents radiation and convection, is applied
at a small distance from the level of the metal but not in
direct contact with the metal. According to another embodiment
of the invention, the reusable insulating material can be used
on a ladle.


Claims

Note: Claims are shown in the official language in which they were submitted.


The embodiments of the invention in which an exclusive property
or privilege is claimed are defined as follows:
1. In a method of manufacturing cast metal bodies, moulded
iron metal or iron metal alloy castings or ingots, in which teem-
ing is carried out as an up-hill or down-hill casting with at
least one of mould paint and casting flux applied to the casting
mould or ingot mould, the improvement wherein an insulating
member effective to prevent radiation and convection is, disposed
at a predetermined point in time, adjacent to and spaced apart
from the level of the molten metal so as to substantially
prevent access of outside cooling air to said metal, said
insulating member consisting of ceramic fibres, said insulating
member being spaced from said molten metal such that the molten
metal will not contact the ceramic fibres under normal casting
conditions, and such that the ceramic fibres are not destroyed
by the heat of the molten metal, and such that the insulating
material can be used again during a subsequent or later castings.
2. A method according to claim 1, wherein the insulating
member is arranged in a cover or hood, having a lower side wall
edge abutting an upper portion of the casting mould or ingot
mould.
3. A method according to claim 2, wherein said cover or
hood is formed from a metal plate.
4. A method according to claim 2, wherein an insulating
material less heat resistant than ceramic fibres is disposed
between said insulating member and said cover or hood.
5. A method according to claim 4, wherein said insulating
material comprises mineral wool.
14

6. A method according to claim 1, wherein said teeming
comprises an up-hill casting and said insulating member is
disposed adjacent said level of molten metal after placement
of a hot top in the mould.
7. A method according to claim 1, wherein said teeming
comprises a down-hill casting and said insulating member is
disposed at the conclusion of the casting operation.
8. A method according to claim 1, wherein said member is
a board or matting of ceramic fibres.
9. A method according to claim 1, wherein said member
is a board and an aluminum foil is arranged on at least one side
of said board.
10. A method according to claim 1, wherein said member
comprises a plurality of boards and an aluminum foil is disposed
at least between two adjacent boards.
11. A method according to claim 9 or 10, wherein aluminum
foil is disposed on the insulating member surface facing the
molten metal.
12. A method according to claim 2, wherein said member
comprises a board and an aluminum foil is arranged on the board
surface which is facing the ceiling of the cover or hood.
13. A method according to claim 2 or 3, wherein said member
comprises a board and a first aluminum foil is arranged on the
board surface facing the molten metal and a second aluminum foil
is arranged on the board surface facing the ceiling of the roof
of the cover or hood.

14. A method according to claim 1, characterized in that
the insulating member is arranged in a cover or hood having a
lower side wall edge abutting an upper portion of a ladle from
which the molten metal is poured into the casting mould or
ingot mould.
15. A method according to claim 2 or 14, wherein the lower
Aide wall edge of the cover or hood comprises an angular tab
having a first part resting on an upper portion of the casing
of the ladle, and a second part extending outwardly in a down-
ward direction along the casing of the ladle.
16

Description

Note: Descriptions are shown in the official language in which they were submitted.


103679~
The present invention relates to an improved method
of manufacturing cast metal bodies, for example moulded cast-
ings or ingots, the castings or ingots being composed of iron
metal or iron metal alloys. Conventionally the casting may be
carried out either up-hill or down-hill with mould paint and/or
casting flux placed in the casting mould or ingot mould, an
anti-piping agent being applied in direct contact with the
molten upper portion of the cast metal body immediately
after or just prior to concluded casting.
It is generally known that castings or ingots are
manufactured by means of either up-hill or down-hill casting
and that a casting flux is applied to the bottom portion of
the casting mould or ingot mould in up-hill casting, said
casting flux preventing oxidation by means of preventing
atmospheric oxygen from reaching the steel.
Furthermore, it is generally known to apply an
anti-piping agent directly on top of and in contact with the
molten metal in the casting mould immediately after concluded
casting.
In the manufacture of killed steel ingots a hot top,
for example of the Vallak ~ type, which is applied to the
upper portion of the ingot mould, is almost always used in
order to reduce piping.
Even if the use of a hot top, for example of the
Vallak ~ type, can substantially and economically reduce
pipe formation in ingots, the use of anti-piping agent in
the manufacture of both ingots or castings does not only
~.

~03679~
entail an increased cost of several Swedish ~rowns per ton
casting wei~ht, it also carries with it the disadvantage of
the production of clouds or dust both at and around the castin~
pit and therewith pollu~ion of the working area~ not forgetting
possible health hazards encountered by persolmel in the form
of the spread of dust and other ~articles in the air. Due to
labour safety legislation in efect in most industrial nations,
the use of unhealth~ anti-?iping agents has been prohibited.
~lowever, at the same time as such legislation has resulted in
a smaller risk for personnel, the cost of anti-pipin~ agents
has increased as it is no longer possible to choose inexpensive
material for the production of anti-piping agent~ said
materials mostly being a health hazard~
The application of ceramic fibres adjacent to but not in
contact with the molten material, which has a temperature of
approx. 1600C, has never been considered previously~as the
material would be expected to be destroyed by the molten metal.
However~ it was found that the fibre--board in auestion not only
maintained its integrity after the manu*acture of the first
ingot but it also maintained its integrity after the manufac-
ture of further ingots. Later, aluminum foil was placed between
the ceramic fibre plates, the idea being that the reflecting
aluminum foil would radiate the heat back to the molten
material. Quite unexpectedly and contrar~ to the theoretical
expectations, the aluminum did not melt. After this, experi-
mentation was broadened with one or several layers of ceramic
fibre material, one or several alu~inu~ -Foils etc. 3 all of
which led to the present invention.

- ~03679i
The fact that the heat from the still molten metal did
not destroy the ceramic fibre material lying a slight distance
above said molten metal is, in itself, perhaps explainable, but
the fact that the aluminum foil applied to the ceramic material
(the ceramic material can have a melting point which is sub-
stantially greater than 1600C but the aluminum foil has a melt-
ing point about 660C) did not melt is surprising, This surpris-
ing result can be attributed to a synergetic effect in a com-
bination of a ceramic material, in this case fibre material, and
an aluminum foil.
According to the invention there is provided in a
method of manufacturing cast metal bodies, moulded iron metal or
iron metal alloy castings or ingots, in which teeming is carried
out as an up-hill or down-hill casting with at least one of
mould paint and casting flux applied to the casting mould or
ingot mould, the improvement wherein an insulating member
effective to prevent radiation and convection is disposed at a
predetermined point in time, adjacent to and spaced apart from
the level of the molten metal so as to substan~ially prevent
access of outside cooling air to said metal, said insulating
member consisting of ceramic fibres, said insulating member being
spaced from said molten metal such that the molten metal will
not contact the ceramic fibres under normal casting conditions,
and such that the ceramic fibres are not destroyed by the heat
of the molten metal, and such that the insulating material can
be used again during a subsequent or later castings.
In the method of the invention cast m~tal bodies, for
example moulded iron metal or iron metal alloy castings or
ingots, are manufactured in a method in which teeming is carried
out in the form of an up-hill or down-hill casting with mould
paint and/or casting flux placed inside the casting mould or
ingot mould, the method being characterized in that instead of
? - 3 -

103679i
conventionally employed anti-piping agent there is employed an
insulating member which prevents radiation and convection and
which is applied at a suitable point in time, that is, in down-
hill casting when the casting is completed and in up-hill casting
at any time after the placement of the hot top in the ingot
mould, at a small distance from the level of the metal, i.e.
the molten metal with molten slag substance possibly flowing
thereupon (subsequently referred to only as molten metal or
molten steel), but not in direct contact with the metal, thereby
substantially preventing outside cooling air from entering, the
insulating member being suitably in the form of plate, board
matting or the like consisting of ceramic fibres, the insulating
member, if desired, being provided on at least one side with an
aluminum foil, the slight distance being chosen so that it is
large enough that the molten metal will not reach up to the
insulating member in normal casting conditions and large enough
that the ceramic fibres not be destroyed by the heat of the
molten metal, and so that the insulating member can be used again
and applied during the subsequent or later castings.
The method according to the invention is further
characterized in that the insulating material is applied arranged
in a cover or hood, the lower side wall edge of which abuts the
upper portion of the present casting mould or ingot mould. The
ceramic fibre material can advantageously be arranged in such a
manner in the cover/hood that the most heat resistant ceramic
fibre material is placed nearest the surface of the molten metal.
A less heat resistant ceramic fibre material is placed thereafter,
etc. In other words, the heat resistance of the ceramic fibre
material decreases as the distance to the surface of the molten
metal increases. In this manner the cost of the ceramic fibr~
material, which is placed in the cover/hood, can be reduced.
; - 4 -

'1036791
The method according to the invention is further
characterized in that metal plate made of for example aluminum,
iron etc. is used as material for the cover or hood.
Ceramic fibres comprise for example A1203 and SiO2
fibres, Fiberfrax ~ , Kaowool ~ , ZrO2 or Cr203 fibres. High
temperature resisting, but not ceramic fibres comprise for
example mineral wool, which has a temperature resistance of
only about 800C.
Further aspects of the invention are characterized
in that an aluminum foil is arranged on at least one side of an
insulating plate or that an aluminumfoil is arranged at least
between two plates if there are more than one insulating plate,
or that an aluminum foil is arranged on the insulating plate
surface which is facing the molten metal, or that an aluminum
foil is arranged on the insulating plate surface which is facing
the ceiling of said cover or the bottom surface of said cover.
According to another aspect of the in~ention, an
aluminum foil can be arranged on the insulating plate surface
which is facing the molten metal as well as on the insulating
plate surface which is facing the inner surface of the ceiling
(roof) of the cover.
According to another embodiment of the invention the
reusable insulating cover, as a whole or as sections which can
be joined together, can be used on a ladle. During pouring from
the ladle into one or a plurality of ingot moulds, reusable
insulating covers are also used on the ingot mould or moulds.
The invention is illustrated in particular and preferred
embodiments by reference to the accompanying drawings in which:
FIGURE 1 illustrates an ingot mould in conjunction
with an insulating member disposed in
accordance with one embodiment of the
invention, and
r: ~ ~ 5 _

~036791
FIGURE 2 illustrates a ladle in conjunction with an
insulating member disposed in accordance with
another embodiment of the invention.
The method according to this other embodiment of
the invention is characterized in that the insulating
material is applied arranged inside a cover or hood 3, the
lower side wall edge 7a of which abuts the upper portion
of the ladle 8 used in casting/ from which, in a manner
- 5a -

1036791
known in itself, the liquid metal is poured into the casting
mould or ingot mould.
The above-mentioned method is further characterized in
that the lower side wall edge 7a of the cover or hood 3 is
furthermore designed as an angular tab 7a + 7b, the angular
tab part 7a of which rests on the upper portion of the casing
9a of the ladle 8, while angular tab part 7b extends outwardly
in a downward direction along the casing 9a of the ladle.
In the enclosed drawings Fig. 1 shows a possible
arrangement for carrying out the method according to the
invention. Fibre-board or plates 1 are arranged inside a cover
3 made of sheet iron, aluminum plate or similar suitable
material, an aluminum foil 2 if desired, and further the cover
3 with its contents being arranged on an ingot mould 5 provided
with a hot top 4, said cover and its contents, that is the
ceramic material 1 and possible aluminum foils 2 being
arranged at a distance above the level of the metal immediately
after or just prior to concluded pouring of an ingot 6 (the
same applies to a casting mould in up-hill or down-hill
casting).
Fig. 2 in the enclosed drawings shows still another
possible arrangement for carrying out the method according to
the invention9 said arrangement, as in Fig. 1, having the
fibre plate or plates 1, the cover 3 and the aluminum foil 2.
The cover 3 along with its contents is now arranged on a ladle
8 which, as known, consists of a ladle casing 9a having
dowel(s) 9b for a lifting hook, refractory lining 10, nozzle 12
or stopper rod (not shown) and contains liquid metal, for
-6-

1036791
example steel 6. In this case the lower portion of the plate
casing of the cover 3, said lower portion resting on the upper
portion of the ladle casing 9a, is formed as an angular tab 7a
~ 7b, whereby angular tab part 7a rests on the upper portion of
the ladle casing 9a and angular tab part 7b extends outwardly
in a downward direction along the ladle casîng 9a.
Fig. 2 shows a l~dle without any stopper arrangement ,
but the cover ~ can be advantageously used for ladles whose
opening/teeming hole 11 is adjusted via stopper rods and/or
~0 sliding gate nozzles. When stopper rods are arranged on ladles
the plate casing of the cover 3 is designed in such a manner
that the upper portion of the stopper rod having an upper
manoeuvring arm or sliding arm is covered preventing air
exchange between the steel and the environment. The cover can
also be advantageously designed in such a manner that recesses,
holes or slots are provided on the cover, in which a stopper
rod or several stopper rods fit without resul~ing in that the
function or effect of the ceramic fibres is reduced. The
ceramic fibre material can further be attached in various ways
to the plate casing of the cover, for example by means of
reinforcement wire, nails and the like in the fibre material
itself, increasing the mechanical strength of the ceramic
fibre material, said wire, nails etc. being attached to said
plate casing. Said reinforcement wires, nails etc. should be
2S positioned in such a manner that they are not subjected to
direct heat radiation from the metal bath.
In other words~ the ceramic fibre material shall protect
said reinforcement by means of the reinforcement being
--7--

~.036791
surrounded by said material. The ceramic fibre material can
also, in a manner known per se~ be treated with a refractory
bonding agent~ whereby the fibre material is endowed with a
certain self-supporting property.
The invention is further illuminated with the help of
the following examples 1-10.
Example 1
Loose ceramic wool (1) was placed inside a cover (3)
consisting of O.S mm sheet iron, uppermost against the ceiling
of the same, said wool consisting of ceramic fibre having a
SiO2-content of approx. ~8-50~ and an Al203-content of approx.
50-52%. After this an approx. 2.5 mm thick plate/board (1) was
placed inside the cover, said plate/board consisting of approx-
imately the same composition as that of the loose wool (1).
Aluminum foil (2) was laid between these two layers. The
contents of the cover was held in place by the lower edge of
the cover, said edge being bent in towards the ceramic fibre
board (not shown in the figure). The cover was placed on top of
the ingot mould (5) in such a way that the ceramic fibre board
(1) rested directly on the hot top ~4) after concluded pouring
when the metal had reached level (6). After the metal had
solidified, the cover (3) was removed along with its contents
(1 and 2), wherewith it was observed that the shrinkage of the
metal was better than in the ingots, wholse upper sides had
been covered with conventiDnal anti-piping agent. The process
was repeated several times with the sheet iron cover and the
same ceramic material without the result deviating from the
first test, that is, the insulating properties of the ceramic
material remained unchanged~
--8--

~036'7~1 .
Example 2
The same as Example 1 but the aluminum foil (2) was
deleted and the cover (3) with its contents was laid onto the
ingot mould t5) resting on the upper edge of the hot top (4)
S and the cover (3) with its contents of ceramic fibre material
was applied prior to the commencement of the pouring. Six
ingots were poured up-hill~ whereby five of thase were provided
with said arrangement. The sixth ingot mould was not provided
with said arrangement as it was desired to visually see how
quickly the steel rose in the ingot mould and when the pouring
was completed. When this had been observed, the upper portion
of the ingot mould/hot top/ingot was covered with the cover (3)
! containing the ceramic fibre (1). The process was repeated
several times and the result was better than in ingots cast
under the same conditions using conventional anti-piping agent~
Example 3
The same as Examples 1 and 2 but with the difference
that the composition of the ceramic fibre was approx. 56% SiO
approx. 40% Al203 and approx. 4~ Cr203. Even in this example
the shrinking was better than in ingots whose upper surfaces
were covered with conventional anti-piping agents.
Example 4
The same as Examples 1 and 2 but with the difference
that the composition of the ceramic fibre was approx. 43-47%
Al203, 50-54~ SiO2, 0~6-1~8% Fe203 and 1.2-3.5~ TiO2. The same
good results as those of Examples 1-3 were obtained.
Example 5
The same as Examples 1 and 2 but with the difference

1036791
that the loose wool was replaced with a 10 cm thick mineral
wool matting and that two 2.5 cm ceramic fibre plates were
used. The mineral wool mattin~ was hardly affected by the heat
than~s to the protective effect of the ceramic fibre plate.
Exam~le 6
The same as Example 2 but with the difference that in a
very special steel alloy having relatively high Cr and Ni
content, in which exothermal anti-piping agent was applied to
the surface of the molten metal and after the exothermal anti-
piping agent had transferred heat to said metal surface, aninsulating agent consisting of kieselguhr, which is very
health-hazardous, was applied. Instead of using the health-
hazardous kieselguhr material, the cover (3) with the ceramic
fibre (1) was applied. The results obtained therewith were as
¦ 15 good as the results in the previous examples.
Example 7
The same as Examples 1 and 2, whereby a plate consisting
of Al203 and SiO2 was replaced with a plate consisting of Al203.
The results obtained therewith were as good as the results of
Examples 1-6.
Example 8
The same as Examples 1 and 2 but with the difference
that the plate consisting of Al203 was replaced with a plate
consisting of ZrO2 fibres. The results obtained therewith were
as good as the results obtained in the previous examples.
Example 9
The same as Examples 1 and 2 but with the difference
that the upper portion o~ the hot top (4) lay a bit below the
-1 0 -

1036791
upper edge of the ingot mould (5)~ whereby the ceramic fibre
material rested directly on the edge of the ingot mould. Even
in this case, in which the ceramic fibre material still did not
rest upon or stand in direct contact with tl~e smelt, the same
good results as those o~tained in Examples 1-7 cou}d be noted.
Example 10
~ cover of similar construction as those mentioned in
Example.s 1-9 was made to cover the top part of a ladle, whereby
the heat losses from the surface of the steel bath were reduced
lQ considerably through a throughout application of the reusable
ceramic fibres.
Beyond that which was mentioned above, the method
according to the invention yields purely practical and economic
j advantages in the manufacture of ingots or castings made of
steel and the following advantages, listed without any judge-
ment passed concerning the mutual importance of the advantages,
namely
1~ Anti-piping agents used to date, either in a powdered
form or solid form, applied to the level of the metal
immediately after or JUst prior to concluded casting or during
pouring from a ladle~ are omitted entirely.
2. The cost of the anti-piping agent, which is a one-time
cost for each ingot, casting and insulating powder for ladles,
is omitted entirely and only the cost of the ceramic fibre
material exists, said material being able to be used a plurality
of times; the economic gain should amount to several Swedish
Crowns per ton ingot or casting~
3. The use of a firm, reusable ceramic material results in

103679i .
the fact that no dust formation or spreading arises at or
around the casting station.
4. The ceramic fibre material prevents heat escape by
radiation as well as convection from the metal during pouring
from a ladle.
5. The application of one or more aliminum foils prevents
air circulation in the porous layer of the ceramic fibres,
wheréby ~he insulation ability is amplified at the same time
as the aluminum layer applied nearest to the molten material
reflects heat.
6. The synergetic effect of the combination of ceramic
fibres and aluminum foil entails an increased heat re-radiation
and an increas~ heat preservation in the molten metal during
pouring from ladles together with, therewith not unexplainable 7
a reduced radiation of heat to the environment surrounding the
ladle.
7. The method~ by means of which the ceramic fibre material,
possibly with aluminum foils, is arranged at a distance from
the molten metal but in abutting contact with the top of the
ladle, prevents exchange of air and therewith decreases
oxidation of the surface of the molten metal.
8. No dust is formed due to the fact that dust-forming
material is not used.
9. Ingots which are clean~ that is free from dusty material~
are obtained from the pouring from the ladle to the ingot mould
in the warm state~ said ingots being able to be passed on to a
hot-rolling mill directly after casting.
10. By means of, in carrying out the method according to the
-12-

103~7~1
invention, arranging the ceramic J firm, fibrous material and
the aluminum foils~ when used, in a cover, said cover prevents
the spilling and splashing of steel in up-hill pouring
entaîling that entrapments in the ingot are not formed and that
the insulating material is proteoted, that is the ceramic
fibres and possibly the aluminum foils are protected from steel
dr~ppings; this due to the fact that the cover containing the
ceramic material is arranged on the ingot moulds before the
commencement of the pouring. This is of special importance in
the cast~g of ingGts wherein a great number of ingot moulds are
as a rule placed on a bottom plate and cast up-hill, wherein
the metal is poured from the ladle into the trumpet. It is
possible that the pouring stream misses the trumpet and there-
with splashes the steel up into the ingot moulds, said steel
freezing to the walls of the ingot moulds and creating
unrepairable wounds and flaws on the ingot resulting in bad
ingot sur$aces and consequently a poorly rolled product.
-13-

Representative Drawing

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Administrative Status

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Event History

Description Date
Inactive: IPC from MCD 2006-03-11
Inactive: Expired (old Act Patent) latest possible expiry date 1995-08-22
Grant by Issuance 1978-08-22

Abandonment History

There is no abandonment history.

Owners on Record

Note: Records showing the ownership history in alphabetical order.

Current Owners on Record
None
Past Owners on Record
None
Past Owners that do not appear in the "Owners on Record" listing will appear in other documentation within the application.
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Document
Description 
Date
(yyyy-mm-dd) 
Number of pages   Size of Image (KB) 
Cover Page 1994-05-15 1 13
Claims 1994-05-15 3 80
Abstract 1994-05-15 1 13
Drawings 1994-05-15 1 24
Descriptions 1994-05-15 14 477