CA1076179A - Installation for electroslag melting of heavy-weight metal ingots - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

An installation has a hollow cooled mould with a bottom plate at the beginning of melting functioning as a bottom and a cooled protrusion which partially enters the cavity of the cooled mould from underneath at the beginning of melting. The protrusion is of a height exceeding that of the ingot forming walls of the cooled mould, and of a cross section allowing the cooled mould to be lowered down to a level at which the ingot forming section of the cooled mould wall is below the upper end. face of the cooled protrusion.
The installation is compact in size and permits the use of a crane for upward removal of the ingot from the cooled mould.

Description

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AN I~STALLATION FOR ~LECTROSLAG NELTING
. . .; . ., OF HEAVY-WEIGHT METAL INGOTS

The present invention rslates to installations for ele~
ctroslag melting of heavy-welght metal ingots.
Co~monly known are installations for electroslag melting of metal ingots, having vertical columns which mount at least one electrode holder to fix therein one or several consumable electrodes and to feed electric current to them. Mounted on ~ , :
said colu:ns below the electrode holder with possible verti-cal displacement is a cooled mould pos~tioned on a cooled bot~
tom plate forming a bottom of the mould.
The mould has a through cavity whose upper portion is of wider cross section than the lower one.
The wider upper portion of~theccavity of the cooled mou1d is intended to accommodate a slag bath and to melt-down consumbale electrodes therein, while the lower more narrow portion of the cavity of the cooled mould ls intended to col-lect molten metal for its crystallization into an ingot. The . ~ ., , -value of the cross section of the cooled mould lower portion is selected so that to be substantially close to the value of ~;
the cross section of the consumable electrode subJect to melting-down or to the total value of the cross-sectional areas of several consumable electrodes sub~ect to simultane-ous melting-down.

In the course of electroslag melting of metal, the con-sumable electrodes and the bottom plate remain stationary, while the cooled mould is displacing upwards as the ingot is being built up.
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~ o~ 79 In an installation described by the Canada Patent N 853808, the hollow cooled mould is placed on the bottom -plate with the protrusion which at the beginning of melting fully enters the cavity of~.this mould from underneath. The upper end face of this protrusion is positioned considerably .,,: -below the ingot forming section of the cooled mould.

A space is left above the protrusion in the lower por-:: . .
tion of the cooled mould cavity for forming the bottom por-tion of the metal ingot being produced. In the course of melting up the ingot, first portions of melted metal harden stop the end face of the protrusion.
With the height of a built-up metal ingot increasing, , .
the cooled mould is being raised up correspondingly.
The rate of ingot growing-up and correspondingly the speed raising the cocled mould are selected with respect to ~ ~-the conditions ensuring the melting Oe a high-quality metal ingot.
For this purpose the cooled mould is moved upward so that almost the entire upper portion of a crystalli~ed ingot ~-is located in the lower ingot-forming section of the cooled mould. -On completion of melting~down o consumable electrodes the cooled mould i5 emptied of slag. Also removed (taken out) `
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are discarded ends of consumable electrodes together with standard parts of electrodes~ to which the ends of consumable `
electrodes are attached (welded on). The cooled mould is :, ,; . :., ,; '' - ~
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coved upward until a produced metal ingot fully goes out from its lower portion, thereafter a carriage with the bottom ~
plate together with an ingot placed thereon is rolled out of -`
the melting installation.
Used with this known instailation for melting metal ingots weighing Erom 150 to 200 t and more heavier are usual- - ;
ly relatively short consumable electrodes, with the length of each of them equal to the height of an ingot being prod~
ced. The consumable electrodes are secured in the electrode holder mounted on a relatively simple metal structure, for example, on columns with guide members for vertical displace~
ment of the cooled mould longitudinally in relation to the columns.
; So, the known installation is able to solve the problem ; ~ ~ of producing heavy-weight metal ingots.
However, the known installation cannot do without rela-tively long standard parts to which consumable electrodes are welded on. In melting in~ots weighing up to 200 t the length of the standard parts is as high as 4 to 5 m. This is dictated by the fact that on completion of the melting pro- ~;~
cess the cooled mould should be raised up untll the head portion of an ingot fully goes out of the cooled mould cavi-`::
ty. And because the consumable electrodes are secured statio-nary on the standard parts the reserve upward stroke of the cooled mould along the columns can be ensured only as a re~
sult of incressing the length of the st;ndard parts at IrGst '; '

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''`,'';'.''' ' ' '"' ' ' by the value of the height of the cooled mould forming por-tion walls. This height for ingots of 200 t weight is from 1.5 to 2~0 m.
The increased length of the standard part of the ele- :
ctrode holder leads to growing resistance and inductive reactance of the furnace and this in turn results in a more powerful source of electric energy needed for feeding the ~ -installation. ~' Due to the use of long standard parts the known instal-lation is of a relatively large height and this consequently requires more materials usually steel to be needed for its ~
manufacture. ;~ ;
The principal ob3ect of the present invention is to '-provide an installation for electroslag melting of heavy~
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weight metal ingots which would permlt application of shor-ter standard parts and consequently would be more compact ;~
than the known installation of the similar purpose. ;
The other no less important object is to reduce the ..:. : - .- , , : .
amount of metal needed for the manufacture of an installa~
tion~
One more ob~ect of the invention is to reduce resLstan- ~-.. . .. . .
; ce and inductive reactance of the installation and conse-quently to permit use of a less powerful source of electric `
energy or operation of the in~tallation.
The ob~ect of the invention is also to reduce the floor area needed for mounting the installation and to simpliy the furnace design.

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These and other objects are achieved by provision of an installation for electroslag melting of heavy-weight metal ingots by way of melting-down consumable electrodes, compris-ing at least one electrode holder mounted on vertisal columns for fixing therein one or several consumable electrodes and for feeding electric current to them, a cooled mould positio-ned below the electrode holder and mounted for possible verti-cal displacement along the columns and having a through cavi-ty whose clear cross section in the slag bath zone is larger --than the clear cross section in the ingot forming zone and the latter cross section is substantially close in value to the cross-sectional area of one or several consumable electro-des being simultaneously melted-down, a bottom plate positio-ned below the cooled mould and having a vertical cooled pro- .
trusion entering the cavity of the cooled mould from under- ~:
neath and forming a bottom thereof at the beginning of melt-ing, and according to the invention the cooled protrusion on the cooled bottom plate partically entering the cavity of the cooled mould at the beg~nning of melting is of a helght ex- :.
~ 1 . . ' ;~ ceeding that on the ingot forming section of the cooled ~ould wall, and a cross section permitting lowering of the cooled mould down to a level at which the ingot forming section of the cooled mould wall is below the upper end face of the cooled protrusion.

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This shaping of the bottom plate with the protrusion of ~ -said dimensions allows the cooled mould to be lowered to a .,~, - .
position at wh~ch the lower end face of the metal ingot goes beyond the limits of the ingot forming zone for easier extrac-tion of the ingot from the cooled mould by means of crane.
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This in turn, makes it possible to use shorter (twice as shorter) standard parts for mounting consumable electrodes ;~
and also to reduce the length of columns to provide conditions for the creation of a more compact electroslag installation as compared with koown ones.
It is expedient that the height of the cooled protrusion on the cooled bottom plste is 1.05 to 1.2 of the height of ~-the ingot forming section of the cooled mould wall.
&id heigh of the cooled protrusion allows the task of ~ ~-the invention to be successfully solved. This height is suffi~
ciently enough for a crane to grip the ingot and remove it :i from ths ~sttom plate protrusion without inflicting any damage to the ingot forming section of the wall of the cooled mould lowered at this moment down to the extreme lower position.
It is desirable that in the slag bath ~one the cooled mould cavity is made flaring upward so that the upper section -of the cooled mould wall, which defines the cavity is at an - ;
angle o 2 to 10 to the vertical.
The cited limits of the angle of inclination of said ~'~
section of the cooled mould wall permit for unrestricted down- ~:
ward displacement of the mould at the end of melting and for -''.

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~' releaving the ingot bottom portion from the forming portion of the mould when the mould is loca~ed on the upper end face of the protrusion positioned above the level of ~he ingot forming section of the cooled mould wall.
At angles of inclination of the upper section of the `~
cooled mould wall less than 2 the upper portion o the coo-led mould may get blocked with solidified slag. '' At angles larger than 10 the overall dimensions of the ~' upper portion of the cooled mould are considerably and un-reasonably increased.
other objects and advantages of the present invention will be more clearly understood from the following detail : . :
description of an installation for electroslag melting of !`.~ ' heavy-weight Detal ingots with reference to the accompanying , drawing,s,, in which:
Fig.l is a vertical sectional view of an installation at the initial period of melting;

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~ Fig.2 is a view of the same installation as in Fig.l at ~ ' :`:
the end of melting when the ingot is gripped for its further '~
removal from the bottom plate protruslon.
An installation for electroslag melting of heavy-weight metal ingots includes vertical columns 2 (Fig 1 and 2) moun-ted on a base 1. Secured on the columns is an electrode hol- ' der 3 (Fig.l) held by upper cross members 4 with an opening 5. ~-Fixed in the electrode holder 3 are standard parts 6 for feed~ ';
ing electric current to consumable electrodes 7. '' ' " ' '~' ' ' . '', , ,, , ;.
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Mounted on lower cross members 8 with possible vertical displacement along the columns 2 is a cooled mould 9 mounted .
on a cooled bottom plate 10. ~ . .
The cooled mould 9 has a through cavity 11 which within -a slag bath zone 12 is of a clear cross section exceeding .
that within the zone of forming a metal ingot 13.
The clear cross section in the zone of forming the metal ; - - `
: ingot 13 is selected to be substantially close in value to .. -the cross-sectional area of one or several consumable electro~
des 7 being simultaneously melted-down. The cav~ty 11 in the '.;
: slag bath ~one 12 of the cooled mould 9 is made flaring up- '!,,, ' ~
:: ward so that an upper section 14 (Fig.2) of the wall of the : :
cooled mould 97 which defines the cavity, is at an angIe ~ ;
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~ to the vertical~ to be within 2 to 10. .~.

:~ . The upper working surface of the cooled bottom plate 10 ., . :
~ : has a vertical cooled protrusion 15 which enters the cavity . ~ .
11 of the cooled mould 9 from underneath and forms the bottom of the mould at the beginning of melting. An asbestos sealing 17 i9 placed in a clearance between the cooled protruslon 15 ~ ;
and a lower s.ction 16 of the wall of the cooled mould 9~ .
The cooled protrusion 15 ls o~ height H which exceeds height h of the wall lower section 16 of the cooled mould 9, which forms the ingot 13, and of a cross section permitting the cooled mould 9 to be lowered down to a level at which the wall seGtion 16 of the cooled mould 9, which forms the ingot -13~ ls below the upper end face of the cooled protrusion 15. ~: : .
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The preferable height (H) of the cooled protrusion 15 on the -cooled bottom plate 10 comes to be 1.05 to 1.2 of the height `~
~h) of the wall lower section 16 of the cooled mould 9, which forms the ingot 13. Displacement of the cooled mould 9 is ef-fected by means of a vertical displacement drive (not shown in drawings). The installation can be provided with several electrode holders 3 (Fig.l).
The metal ingot 13 produced by way o melting can be re-moved from the cooled mould 9 by a grip 18 (Pig.2~ of a shop crane (not shown in the drawing).
The installation for electroslag melting of heavy~weight metal ingots operates as follows~

At the beginning of melting~ the cooled mould 9 (Fig.l) :'~
is mounted on the cooled bottom plate 10 so that the cooled protrusion 15 partially enters the lower portion of the cavity 11 of the cooled mould 9. The upper end face of the cooled protrusion 15 is located below the wall lower section 16, which forms the ingot 13, through a distance s~fficient for forming the bottom portion of the ingot 13. Asbestos sealing 17 is placed in the clearance between the cooled protrusion 15 and the wall lower section 16 of the cooled mould 9.
The cavity 11 of the cooled mould 9 is filled with melted slag to creats the slag bath 12 wherein the consumable ele- `
ctrodes 7 are immersed. Then~ from an electric power source (not shown in the drawings) current is fed to the consumable electrodes 7. Electric current flows between the consumable ~;

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electrodes 7 through the slag bath 12 or between the consumable .i: : : . .
electrodes 7 and the protrusion 15 of ~he cooled bottom plate 10 (depending on the electric circuit diagram for connection :.. -. ;
to electric power source). This lib.erates heat which heats up . . ;.:
the slag bath 12 up to the melting ~emperature of the consumable .:
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electrodes 7. Liquid metal gets on the upper end face of the protrusion 15, whereon it cools down and hardens into the metal ingot 13. -.
Upon forming of the lower portion of the metal ingot 13 .~
~ :, .~ ~ in the sapce below the wall lower section 16 of the cooled : mould 9~ the latter is moved upward by means of the drive tnot .. ; :
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~ shown in the drawings) kinematically linked with the lower :~ ~ cross members 8. The cooled mould 9 is lifted to such a value .:
at which the level of liquid metal, as new portions thereof .~.
are being added, is found near the upper end face of the wall ~:~ lower section 16 of the cooled mould 9.
After the consu~able electrodes 7 are melted-down (when ~.
:~ ~ only discarded ends thereof are left at the standard parts 6) ;~
. , the power supply is switched off and the llfting of the cooled ~ .
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mould 9 is discontinued. Thereafter slag is drained from the : upper section 14 of the cooled mould 9 and~ the discarded ends of the consumable electrodes 7 and the standard parts 6 are removed from the electrode holder 3. .. : :
As the ingot 13 is cooled down its cross section is re~
duced and this allows the cooled mould 9 to be lowered to its : ' ex~reme lower position upon the cooled bottom plate 10, at ~:

which the cooled protrusion lS fully enters the cavity 11 of '' ' ': ~:
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''-:', ' . '' ',''' ': :, ' ' ,,',, '",'.'' '; ', , .: ' , ~L076~7~3 the cooled mould 9 from underneath and occupies a position 100-200 mm higher than the upper end face of the wall lower ;
section 16 of the cooled mould 9. To remo~e the metal ingot 13 from the cooled protrusion 15 the grip 18 of a crane is introduced through the opening 5 in the upper cross members -4 and the metal ingot 13 is carried away by the grip.
In the installation described herein, two-meter long standard parts can be used instead of four-meter long ones :, :
utilized in the known installations. This considerably redu- `, ces the total length of the current-bearing standard parts ;~
and consumable electrodes and, consequently significantly lessens reslstance and inductance of the furnace. ~;
This also results in reduced loss of voltage in the stan- ' dard parts and reduced loss of heat liberated when current flows through said parts. ;;' Apart a less powerful source of electric current can be ~
used for operation of the installation. ~ -:: .,. : .
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Claims (3)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. An installation for electroslag melting of heavy--weight metal ingots by way of melting-down consumable ele-ctrodes comprising vertical columns; at least one electrode holder adapted to fix therein one or several said consumable electrodes and to feed electric current to them, and secured on said vertical columns; a cooled mould positioned below said electrode holder and mounted for possible vertical dis-placement along said vertical columns and having a through cavity whose clear cross section in a slag bath zone is larg-er than a clear cross section in an ingot forming zone and, the latter cross section is substantially close in value to the cross-sectional area of one or several said consumable electrodes being simultaneously melted-down; a cooled bottom plate on which said cooled mould is mounted at the beginning of melting; a vertical cooled protrusion on said bottom plate, partially entering the cavity of said cooled mould from under-neath and forming its bottom at the beginning of melting, and being of height exceeding a height of the ingot forming walls of said cooled mould ant of a cross section allowing the cooled mould to be lowered to such level at which the ingot forming section of the wall of said cooled mould is below the upper end face of said cooled protrusion; a drive for displacing said cooled mould in vertical direction.

2. An installation as set forth in claim 1, wherein the height of said protrusion on said bottom plate comes to be 1.05 to 1.2 of the height of the ingot forming section of the wall of said mould.

3. An installation as set forth in claim 1, wherein the cavity of said cooled mould in the slag bath zone is made flaring up so that the cavity-defining upper section of the wall of said cooled mould forms 2° to 10° angle to the vertical.