CA1180873A - Strip casting apparatus - Google Patents

Strip casting apparatus

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Publication number
CA1180873A
CA1180873A CA000377164A CA377164A CA1180873A CA 1180873 A CA1180873 A CA 1180873A CA 000377164 A CA000377164 A CA 000377164A CA 377164 A CA377164 A CA 377164A CA 1180873 A CA1180873 A CA 1180873A
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CA
Canada
Prior art keywords
casting
set forth
side portion
orifice passage
inch
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000377164A
Other languages
French (fr)
Inventor
Robert E. Maringer
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Battelle Development Corp
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Battelle Development Corp
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Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D15/00Casting using a mould or core of which a part significant to the process is of high thermal conductivity, e.g. chill casting; Moulds or accessories specially adapted therefor
    • B22D15/04Machines or apparatus for chill casting
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/005Continuous casting of metals, i.e. casting in indefinite lengths of wire
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B22CASTING; POWDER METALLURGY
    • B22DCASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/06Continuous casting of metals, i.e. casting in indefinite lengths into moulds with travelling walls, e.g. with rolls, plates, belts, caterpillars
    • B22D11/0637Accessories therefor
    • B22D11/064Accessories therefor for supplying molten metal
    • B22D11/0642Nozzles

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Continuous Casting (AREA)
  • Nitrogen And Oxygen Or Sulfur-Condensed Heterocyclic Ring Systems (AREA)

Abstract

STRIP CASTING APPARATUS
Abstract of the Disclosure An apparatus for continuously casting metallic strip material is disclosed, comprising a tundish, and a nozzle comprising a curvilinear element, with an orifice passage in the element having substantially uniform cross-sectional dimensions throughout the longitudinal extent thereof. Disposed outside the nozzle is a cooled casting surface movable past the nozzle in a direction substantially perpendicular to the longitudinal axis of the orifice passage. First and second inside surfaces of the element define the orifice passage through which molten metal is fed to the casting surface.

Description

1 srief _summary of the Invention The subject matter of the following C~nadian patent applications is of interest all of which were filed May 8, 1981 and may be referred to: Serial No. 377,201 en-titled "Method and Apparatus for Strip Casting" by Battelle Develop-ment Corporation"; Serial No. 377,216 entitled "Method of Repetitiously Marking Continuously Cast Metallic Strip Material" by Battelle Development Corporation; Serial No.377,13 entitled "Apparatus for Strip Casting" by Battelle Develop-ment Corporation"; and Serial No. 377,152 entitled "StripCasting Nozzle" by Allegheny Ludlum Steel Corporation.
The present invention relates to the casting of strip material at high quench rates and at hish producti~n rates. More particularly, the present invention is directed to an apparatus for rapidly casting thin metallic strip materlal.
The apparent advantages and economic significance of producing thin metallic strip material by a casting process, as cornpared to the conventional rolling or reducing operations, are numerous. The fact that strip casting may be perormed at such high quench rates to produce amorphous material i9 even more meaningful. However, it is equally apparent that there are a multitude of strip casting para-meters which must be controlled or monitored to assure that the cast strip is Oe acceptable quality and of uniform composition and structure. For these reasons, those skilled in the art appreciate the intricacy involved in the develop-men t O:e a commercially successful strip casting apparatus.

'~``?

1 The general concep~ of casting thin metallic materials such as sheet, foil, strip and ribbon was disclosed in the early l900's. For example, U.S. Patents 905,758 and 993,90~ teach processes wherein molten material flows onto a mov1ng cool surface and the material is drawn ~nd hardened thereon into a continuous thin strip~ These references ~each that molten metal may be poured onto the smooth peripheral surface of a rotating liquid-cooled copper drum or disc to form strip materials. Despite early disclosure of such concept, there is no evidence of co~mercial success of strip casting during the early part of the 20th century.

Recently, in U.S. Patents 3,522,836 and 3,605,863 a method for manufacturing a continuous product, such as metallic wire or strip, from moiten metal has been disclosed.
These references teach that a convex meniscus of molten material should project from a nozzle~ A heat extracting surPace, such as a water-cooled drum, is moved in a path substanti~lly parallel to the outlet orifice and ~nto contact with the meniscus of molten ~etal to continuously draw material ~rom the meniscus to form a uniform continuous product. The above-described method is commonly called the ~melt drag" process as the heat extracting surf~ce moving pa~t the meniscus of molten metal at the nozzle orifice Actually has ~n e~fect on the rate of molten metal flow, or drag, through ~he nozzle.

More ~ec~nt strip casting developments focus on relatively narrow refinements in the metallic strip casting art. For ex~mple, U.S. Patent 49142,571 is particularly --3^

~ 1 8~8~3 1 directed to a 810~ cons~ruction in a m~al ~tr~p ca~ting nozzle having ~tringent dimensional requirements. Also, U.S. Patent 4,077,462 pertains to the provision of a specific con6truction for a st~tionary housing above the peripheral S surface of a chill roll used for 6trip cas~ing.

There are a number of other rapid quenching techniques known in the art. For example, melt spinning proce6ses of producing metallic filament by cooling a fine molten stream either in free flight or against 3 chill block have been practiced. Also known are melt extraction techni~ues, such as crucible` meit extraction disclosed in U.S. Patent 3,838,185, pendant drop melt extraction technlques taught in U.S. Patent 3,896,203 and splat cooling explained in UOS. Patent 3,297,436. It has heen ~ound difficult to produce uniform 6heet or 6trip by such alternar.ive techniques of rapid quenching. There are many factors r such as casting temperature and preæsure, auxiliary surface cooling rates, ~urface coatlngs for the casting surface, and the like which appear to affect the product thickness, the quality and the reproducibility of rapidly cast strip material.

De~pite the relatively long history of the art of ~trip casting, and the recent developments in this ~rea~ strip c~sting is no~ a widely acceptecl and commercially ~igniPicant oper~tion at ~he present time~ It appears that vAri~u~ improvementsi modifications and innova~ion~ are r~uire~ in the ar~ to efect~ate a si~nific~n~ commercial lmp~ct in the ~rt of strip ca~ting. In particular, proper rel~tionshlp~ among ~uch vari~ble~ ~8 molten metal tundlsh con~truc~ion, no~zle or~fice ~ze and dimen~ions, ~pacing )873 1 from a casting sur~ace, speed at which such ~urface is moved, quench rates, metal temperature and feed rates, and the like may require more accurate identification and interrelation in order to accomplish the uniformity and conslstency required for successful, commercial production of cast strip. In particular, certain nozzle structures and their dimensional relationship to the castlng surface onto which strip material is cast, have been found to be inadequate to yield uniform strip casting results when utilized in various casting parameters.

Accordingly, a new and i~proved apparatus for casting relatively wide, thin strip material is desired which overcomes the disadvantages of the prior art structures. Such desired apparatus should be reliable, more e~ficient and more effective than the structures disclosed in the prior art, and should lead to reproducibility, uniformity and consistency in strip casting.

The present invention may be summarized as providing a new and improved apparatus for continuously casting metallic strip material. Such apparatus co~prises a tundish and a nozzle comprising a curvilinear element, with an oriice passage in the element having substantially uniform cross-sectional dimensions throughout the longitudinal extent thereof, Disposed outside the nozzle is a cooled ~sting sur~ace movable past the noz%le in a direction subst~ntially perpendlcular to the longitudinal axis of the oriice pa~æ~ga. ~irst and second inside surfaces of the element d~fine the orifice passage through which molten metal is fed to the castlng surface.

~5-~ ~80~73 1 Among the advantages of the present lnvention is the provision of a strip casting apparatus which is capable of continuously casting metallic strip material of substan~ially uniform dimension and substantially uniform quality throughout its length.

Another advantage of the present invention is the provision of a strip casting apparatus havlng a nozzle construction which promotes the efficient rapid casting of metal strip material with a minimum of ~etal turbulence during casting.

An objective of the present invention is to provide a strip casting apparatus capable of reproducing successful strip casting operations.

Another objective of this invention is to provide a strip casting apparatus which can effectuate sufficiently rapid quenching of the produced strip to result in the production of amorphous strip. ~owever, it should be understood that the production of continuously cast crystalline material is equally comprehended by the present invention~

A further objective of this invention is to identify certain design and dimensional requirements, particularly with regard to nozzle structure~ which per~it continuous ~nd repetitious rapid casting of metallic strip ~aterial o~ uniorm dimension and unifor~ quality.

~5 These and other objectives and ~dvantages wiil be more fully understood and appreciated with reference ~o the followlng detailed description and the accompanying draw~ngs.
~6--~ ~8~)873 1 ~rief Descri~tion of the Draw~ngs Figure 1 is an elevation view, partially in cross-section, illustrating a typical apparatus used for continuously casting strip material.

Figùre 2 is a cross-sectional view of a nozzle of the present invention.

Figùre 3 is a perspective view of a curvilinear element which forms a nozzle of the present invention.

Figure 4 is an enlarged frag~entary cross sectional view through the orifice passage of the element shown in Figures 2 ~nd 3.

Fisùre 5 is an elllaryed fragmentary cross-sectional view through the orifice passage of an alternative element of the present Invention.

~igure 6 is a cross-sectional view of the orifice passage of an ~lternative element of the present invention.

Figure 7 is an enlarged~ fragmentary cross-sectional view, illustrating an alternative orifice passase in an element of the present invention.

Figure 8 is an enlarged fragmentary, cross-sectional view, illustrating an alternative orifice passage in an ele~ent o~ the present inYentien.

Detailed DQscription Re~erring partlcularly to the drawingsr ~igure 1 generally illustrates an apparatus for casting metallic --7~

7 ~

strip material lo ln accordan~e with the present invention.
This apparatus includes a castin~ drum, wheel, belt, or the like upon which the strip 10 is cast. In a preferred e~bodiment a continuous strip 10 is cast on~o ~ smooth, S outer peripheral surface 14 of a circular drum or wheel as shown in Figure 1. It should be understood that eonfigurations other than circul~r may be employed. ~or example, a wheel with a smooth, frustoconieal outer peripheral surface (not shown) may be employed. Also, a belt capable of rotating through a generally ovular path may be e~ployed as the casting element, Regardless of the configuration employed, the casting surface 14 should be cooled to a temperature below the solidus te~perature of the metal being cast and should be at least as wide as the strip to be cast.

In a preferred embodiment, the casting element 12 comprises a water cooled, precipitation hardened copper alloy wheel containing about 98~ copper with about 2~
chromium. ~opper and copper alloys are preferable because of their high thermal conduct~vity and wear resistance, however, berillium copp~r ~lloys, steel~ brass, aluminu~, ~luminum alloys or other materials ~ay be utilized alone, or in combination. ~or example, ~ultipiece wheels having outer peripher~l ~leeves of molybdenum or other material may be ~p~oyed~ Likewise, coollng m~y be Accompliæhed with the 2S U~ of a ~edi~m other than water. Water is typic~lly chosen ~or its low ~os~ &nd lts ready ~vail~bllity.

In the operation of the strip castlng apparatuS
of the present ~nventlon, the surf~ce 14 of the c~sting wheel ~2 ~ust be ~ble ~o ~bsor~ ~he ~eat g~nerated by 1 contact with m~lten metal at the initial castiny point 16, rnd such heat must be conducted ~ubstantially into the copper wheel during each rotation of the wheel. The initial casting point 16 refers to the approximate location on the casting 14 where molten metal 20 flowing from the tundish 22 cont3cts the casting 6urface 14~ Cooling, by heat conduction, may be accompl~shed by delivering a suffi~ient quantlty of water through internal passageways located near the periphery of the casting wheel 12. Alternatively, the cooling medium may be delivered directly to the underside of ~he casting surface. Understandably, refrigeration techniques and the like may be employed to accelerate or decelerate cooling rates, and/or tv effectuate wheel expansion or contraction dur~ng strip casting.

Whether a drum, wheel or belt is employed for cas~ing, the casting surface should be generally smooth and symmetrical to ~aximize uniformi~y in strip casting. For exampl2, ln certaln ~trip casting operations the distance between the outer peripheral casting ~urface 14 ~nd the surf~ces de~ining the orifice p~ssage of the nozzle which is feeding th~ molten material onto the castin~ surface 14 must not devi~te fro~ ~ desired or set distance during the castlng operation. This distance shall hereinafter be called ~t~ndoff distance or gap. It is und~r~tand~ble that the g~p should be ~ubstantially maint~ine2 ~hroughout the c~ting oper~tion when it is the intention to ~st uniform ~trlp material.

It ~hould be und~r~tood that lf the ~asting i~ p~r~on~ed on a rot~tlng body 12~ ~uch as ~ dru~ or a 08 '~3 1 wheel; the body 12 should be carefully constructed so as not to be out of-round dur~ng operation to insure unifor~ity in gtrlp ca~t~ng~ Alo~g these lines~ lt h~s been found that a dru~ or wheel whlch is out-of-round by about ~.020 inch, or ~ore, may h~ve ~ ~agnitude of dimensional lnstability wh~ch unless corrected or comp@nsated during operation, may be una~ceptable for c~rtain strip casting operations. It has been found that acceptable dimensional symmetry, as well as the elimination of problems assoclated with weld porosity may be more readily a~co~plished by fabricating a wheel or drum fro~ a single, integral slab of cold rolled or forged copper alloy. However, as mentioned above alternative materials including sleeves and coatings may be employed.

The molten material 20 to be cast in the apparatus lS described herein ls preferably retained in a ~rucible 22, or tundish, which is provided with a nozzle 24. The nozzle is typically, though not neces~arily, located at a lower portion of the tundish 22 as shown in lFigure 1~ As will be apprecisted fro~ the foregoing dlscus~ion, the nozzle comprises a curvilinear ~lement 24 in the tundish ~2~

The curvilinear element 24, located in or forming a lower portion o~ the tundish 2~ is best shown in the tundi~h 2~ ln ~igure ~, and in perspective vi~w in Figure 3.
A~ 8hown ln the dr~wing/ an orifice pa~sage 30 i~ preferably
2$ 8ub8tantiMlly centr~lly located in the nuzzle ~lement 24.

SUch approxim~e centr~l location of the ori~lce pas5age, or ~lot, ~0 helps to assure uniform~ty ~s the pressure of the ~olten ~et~l bearing ~here~gainRt i~ ~ubs~antially equalized during ~be c~tin3 oper~tionc It should be under~tood, 1 ~(J8'73 1 however, that the slot may ~e located in off-center positions as may be desired.

The longitudinal extent of the orifice passage 30 should approximate the width of the strip to be cast. There does not appear to be a limitation on the longitudinal extent of the orifice passage, and, passages as long as thirty six inches, or longer, in a curvilinear element are comprehended by the present invention. It is highly desired that the molten metal flow uniformly ~hrough the orifice passage 30 in the curvilinear element 24 of the present invention in order to form uniform, high quality strip material. In an alternative embodimen~, strip of various widths may be produced by cutting multiple longitudinally aligned orifice passages 30 of appropriate longitudinal extent in the curvilinear element 24 forming the nozzle of a tundish 22, as opposed to a single orifice passage 30.
Regardless of the size of the orifice passage 30, or passages, the cross-sectional dimensions of each passage 30 should be substantially uniform throughout the longitudinal extent thereof to produce strip material having uniform dimensions. In the operation of the strip casting apparatus of the present inven~ion, the cooled casting surface 14 moves past the orifice passage 30 in a direction substantially perpendicul~r to the longitudinal axis of the passage 30.

As best shown in Figure 4, the orifice passage 30 is deflned between a first side portion 32 and a second side portion 34 of the curvilinear element 24. The fir~t side portion 32t i~ located on the downstream side of the orifi~e passage 30, with respect to the direction of movement ~ ~8~1~73 1 of the casting surface 14 ~ndlc~ted by the arrow ~n Figure 4. ~he first side portion 32 ha~ ~n ln~de surface 36 which, preferably, 1~ sub~tantially pl~nar, ~nd an outer lip projecting ~urface 38 disposed toward and facing the cast~ng surface 14. At a downstream locatlon from the orifice pa86age 30, the outer lip projecting ~urf~ce 38 is relieved, ~uch as at 40, to define a lip projection 42. The second ~ide portion 34 i8 located on the upstream side of the orifice passage 30, with respect ~o the direction of movement of the casting surface 14 indica~ed by the arrow in Yigure 4. The seeond ~ide portion 34 ha~ an inside ~urface 46, which preferably, i6 8ubst~ntially planar and, also preferably, 1~ ~ubstantially parallel to afld facing the inside 8urface 36 of the fir8t side portion 32 at least at lS an outer portion of the orifice passage 30 with respect to the direction of metal flow ~ro~ the tundish 22 thro~gh the pa~age 30. A bottom surface 48 of the second ~ide portion 34 i~ di~posed toward and facing the ca~ting surface 14.

In a preferred embodiment, the outer lip projecting ~urface 38 of the first ~ide portion 32 ~nd a portion of the bottom 8urface 48 of the 8econd side portion 34 are ln substantially complete paralleli~m with the casting surface 14 movable therebelow. When utllizing a drum or wheel, and a grindable curvilinear element 24, ~ueh aubstantially ~5 ~omplete par~llell~m may be accompl:Lshed by placirlg a ~heet D 18t)87~

1 of sandpaper9 or the like, against the casting surface 14 with the grit side of the sandpaper facing the curvilinear element 24. By moving the curvilinear element 24 into tight contact with the castlng ~urface 14, with the sandpaper disposed therebetween, and by moving the casting surface 14 a~d sandpaper slmultaneously past the nozzle 24, the outer lip projecting surface 38 of the first side portion 32 and the botto~ surface 48 oE the second side portion 34 are ground by the grit side of the sandpaper into substantially comple~e parallelism with the casting surface 14. Such parallelism may be achieved on most refractory nozzles, even when round or other curvilinear casting surfaces are employed.
To achieve such parallelism by this procedure 400 or 600 grit sandpaper has been found to be adequate.

By maintaining at least a portion of the outer lip projecting surface 38 in comple~e parallelism with the casting surface 14, the standoff distance, or gap h, between the outer lip projectlng surface 38 and the casting surface 14 may be maintalned throughout the length of the projection 42. ~t has been found that the gap h between the ou~er lip projecting ~urface 38 and the castin~ surface 14 ~us~ be maintained at less than about 0.120 inch in order to successfully cast strip material. Preferably, this gap h is ~aintained at less than about 0.080 lnch and for casting certain alloys into ~hin gage s~rip, a gap h o~ less than 0,010 is preferred. It has also been found that the gap h between the bottom surace 48 of the ~econd side portion 34 does not Appear ~o be a~ criticalO What is preferred with respect to the ~econd side portion 3~ $s that the inside )873 1 surface 46 thereof extend toward the casting surface 14 while parallel to the inside surface 36 of the first side portion ~32, at least ln an outer por~ion of the orifice passage 30, so as not to interere with the ma~ntenance of a stable flow of molten metal through ~he passage 30 in the curvilinear element 24 and onto the moving casting surface 14. Accordingly, the bottom surface 48 of the second side portion 34 may just clear the casting surface 14, i.e.
within about .002 inch as shown in Figure 7, or, alternatively, the bottom surface 4~ may be tapered from the orifice in a direction away from the casting surface 14, as shown in Figure 8. In any event, the gap h between the bot~o~
surface 48 of the second side portion 3~ and the cas~ing surface 14 must be sufficiently restricted at the nozzle to prevent significant molten metal backflow therebetween during casting.

In an ~lternative embodiment, shown in Figure 5, the inside surface 36 of the first side portion 32 extends through a curvilinear surface 50 to the outer lip projecting surface 38, rather than through the abrupt 90 juncture shown in ~igure 4. Providing such radiused corner surface 50 has been found beneficial in the production of cer~ain grades of strip material~ More particularly, such radiused corner surface 50 helps minlmize molten metal turblllence durlng strlp casting and, t.herefore, results in more uniform production parameters. I~ has also been found th3t a ~harp corner between ~he inside surface 36 ~nd the outer 11p pro,ec~ing surface 38 may be subjec~ed t~ various pressur~s and flow p~tterns which could create ~tress 1 ~8~8~3 1 conditions for curvil~near elements 24 made of certaln materials and, in some ins~ances, may break, crack or wear during casting thereby upsetting balanced ~trip casting conditions. Providing such rounded corner ~urface 50 may minimize the adver~e affect~ of such turbulence and metal flow through the ~urvilinear element 24 compri~ing the nozzle of ~he tundish 22.

To further minimize turbulence during strip casting through the apparatus of the present invention, an inslde portion of the orifice passage 30 may be relieved, or tapered. As shown in the drawlng, both the f~rst side portion 32 and the second ~ide portion 34 may be cut into a V-shape, or a more rounded U-shape at an ln~ide portion theeeof, creating an inltial funnel type structure, which fuxther maxim~zes uniformity in metal flow patterns and minlmizes irregularities or turbulence during strip casting.

Another preferred arrangement, whtch minimi.zes molten metal turbulence during strip casting, is to arrange the curvilinear element 24 at an angle such that the metal is ~ed in the ~ame direction as the casting ~urface 14.
Thls may be accompl~shed by disposing the inside surfaces 36 and 46, defining the orifice passage 30, tow~rd the casting surace 14 at an angle of less than about 90, or preferably ~t an angle of ~bout 45. By such arrangement the flowing 2~5 moltan metal i~ nvt subjected to as ~e~ere a change in flow rate as would be experl~nced by arranging the orifice pas~age 30 to ~eed molten metal perpendicular ~o the casting ~urface 14.

~ 18~73 1 The crucible 22 is preferably constructed of a material having ~uperior insulatlng abillty. If the insulating ~billty is not sufficient to retain the molten material at a relatively constant temperat-lre, auxlliary heaters such as induction coils may have to be prov~ded in and/or around the crucible 22, or resistance elements s~ch ~S W1LeS may be provlded. A convenient material for the crucible is an insulating board made from fiberized kaolin, a naturally occurring, high purlty? alumlna-silica fire clay. Such i~nsulating material is available under the trade OL~
name ~Y~e~ HS board. ~owever, for susta~ned opera~ions, and for casting hlgher melting tempera~ure alloys, vario~s other materials may have to be employed for constructing the crucible 22 or the curvilinear element 24 ~ncluding graphite, alumina graphite, quartz, clay graphite, boron nitride, silicon nitride, sillcon carbide, boron carbide, alumina, zircon~a and various combinations or mixtures of such materlals. It should also be understood that these materials may be strengthened; for example fiberized kaolin may be strengthened by impregnat~ng wlth a sll~ca gel or the like.

It is imperative that the orifice passage 30 of the curv~linear element 24 remain open and its configurat~on remain uubstantlally stable throughout a strip casting operation. It ~s understandable that the orifice passaye 30 ~hould not erode or clog, slgnificantly, durlng a ~trip ca~ting ~e~uence or the primary ob~ectives of maintalning uniformity in the castlng operation and of minimizing metal flow turbulence in the ~undish 22 may be defeated, Along fr~J ~ ~ an~ ~ _ ~ ~0~3 l these lines, it appears ~hat cer~ain lnsulating materlals may not be able to maintain their dimensional stability over long casting perlods, To obviate this problem, side portions 32 and 34 foxmlng the orif~ce passage 30 of ~he curvil~near element ~4 may be constructed of a material which is better able to maintain dimensional stabllity and ~ntegr~ty dur~ng exposure to hlgh molten metal temperatures for prolonged tlme perlods. Such materials may take the form of a sinsle, gene~ally seml-circular elemen~ 24 with a slot 30 cut therethrough as shown in Figure 3, Alternatively, the curvilinear element 24 may comprise a pair of facing inser~s held in the crucible 22 to form a slot 30 therebetween as shown in Fiyure 6. In a preferred embodiment the orifice passages 30 in single curvilinear elements ~4 may be cut lS ultrasonically to lnsure that the desired slot dlmensions are accur~tely provided~ Such curvilinear elements ~4 may be cons~ructed of materials such as quartz, graphite, clay gr~phite, boron nitride, alumina graphite, silicon carbide, stabllized z~rconla silicate, 2irconia, magnesla, alumina, or other ~milar molten ~etal reslstant material. These curvilinear elements 24 may be held in the crucible 22 mechanically, and/or with the aid of adhesives such as various refractory cementsO

The dr~ve system and hou~ing for ~he drum, wheel or other casting ~urface 14 of the present lnvention should be rig~dly constructed to p~rmit drum rotation wlthout ~tructural instabili~y which could cause the drum to sllp or vibrate. In particular, c~re should be taken to ~void re~onan~ frequences at ~he opera~ing ~peeds for the casting 87~

1 surface 14~ The casting surface 14 should be capable of moving at a surface speed of from about 200 linear surface feet per minute to more that about 10,000 linear ~urface feet per minute. When utilizing a drum having a circumference of about 8 f~et, this rate calculates to a drum ~peed from about 25 r~p to about lZ50 rpm~ A three horsepower variable speed reversible, dynamically braked motor provides an adequate drive sys~em for an integral copper alloy casting drum about 2 inches thick and about 8 feet in circumference.

In one embodiment, the casting surfa~e 14 on the wheel or drum of the apparatus of the present invention is smooth. It has been found that in c~rtain applications, such as for produclng amorphous materials, finishing the peripheral surface 14 of a casting drum 12 with 400-grit paper and ~referably with 600-grit paper may yield lmproved product uniformity.

In a preferred embodiment as illustrated in Figure 2, the crucible 22 is cons~ructed of an insulating board, such a Kaowool HS Board~ and the curvilinear element 24, as shown in Figure 3, is made of clay graphite, a molten metal resisten~ ~aterial, held in the walls of ~he crucible 22~ The orifice passage 30 is cut ultrasonically ln the clay graphite element 24. The firs~ side portion 32 ~nd the second ~lde portion 34 of the curvi]inear ele~ent 24 defin~ the orifice pas~age~ or slot, 30 therebetweenO As an alternative, preferYed examples of curvilin~ear els~ent 24 materialæ, a plate made of qu~rt% or *~ material~
whi~h ~re highly molten metal r~s~tent materials~ having a ~r~ k 1 w~dth such a~ about one and one-half inch may be bent ~round an appropriate ~mall radius, as shown in the dxaw~ng.
Alternatively, the curvilinear element 24 may com~ise cast boron nitride. Tbe desired slot formlng the oriflce pa~sage 30 in the curvil~near element 24, may be accurately cut therein with an ultrasonic drill. ~ preferred on~ piece, curvilinear element 24, as best illustrated in Fig~res 2,
3 and 4 may be constructed of a semi-circular rin~ of molten metal resistent material. In ~his example, a slot b having a width of abou~ 0.010 to about 0.080 inch between parallel inside surfaces 36 and 46 may be ultrasonlcally dr~lled into a clay graphite insert material, and the insert may be mo~nte~ into the crucible 22 as shown in Figure 2. It should be understood that the design of the outer, peripher~l edges of such curvilinear element nozzle may be modified to asslst in holding the curvillnear element 24 ln the walls of the crucible 22.

A preferred orifice passage 30 ln a curvilinear element ~4 of the apparatus of ~he present invention is shown in enlarged cross-section in Figure 4. In one embodiment o~ this apparatus, the dimensions indicated in Fiyure 4 may have the following preferred limita~lons, more preferred preferred d~men~ion ~ tion limitation lim1tat1on a bottom sur~ace at least .001 inch .25 - .50 inch o~ second side portion b wldth of orifice .010 - .080 lnch ~025 ~L035 inch pas~age c outer llp pro ,01 - .16 inch oO2 ~ ~06 lnch ~ectlng ~urface length ~()g7~

more preferred preferred dlmension ~ ml~a~ion llmitat~on d rellefat least .01 inch at least .04 inch distance In the product~on of amorphous str~p materlals, the w~dth b of the orlfice passage 30 is typically in the range of Prom about 0.010 to about 0 040 inch. In the production of crystalline str~p material, ~uch as stainless steel, the width b of the orifice passage 30 may be greater, perhaps as high as about 0.080 inch if thick strip is being uniformly produced in accordance with the present invention.

Dimension e, represent~ng the cross-sectional thickness of the curvilinear element 24, f, representing ~he wldth to wh~ch a top portion of the oriflce passage 30 may be rel ieved, and g, representing the depth to which a top port~on of the orifice passage 30 may be rel~eved, appear to be ~omewhat arbitr~ry. Primarily, the purpose of the relief at a top port~on of the orif:loe passage 30, ~dent~fied by d~mensions f and g ln Figure 4, is to eliminate clogging of molten metal in the orifice.

Molten metal turbulence during strip castlng may be m~nim~zed, and perhaps avoided by relievins sharp corners of the nozzle in the direction of ~asting~ It will be understood that such corner relief, such as the r~diused corner ~urPace 50 shown in ~igure 5, may be accompll~hed by construc~ing the curvlllne~r element ~4 of an eroding O~OA
~`~ material, such as ~4w4~ ~S board, wh~ch may provide natural ero~ion as a result of the ~trlp casting operat~on.
3~ Tu~bulence may al~o be avoided by comple~ely round~ng ~he ;~ ~ra~ f/~

1 corner 50 of the projection 42 on the first side portion 3~
of the curvilinear ele~ent 24 as is shown in Figure 5 during or after manufacture thereof.

In an exemplary operation of the apparatus of the present invention, ~olten metal is delivered ~o a heated crucible 22~ It is uslderstood that a heater, such as indùction coils of resistance wire, may be provided in and above the crucible 22 to ~aintain relatively constant molten metal temperatures as may be desired. Alternatively, the molten ~etal may be poured directly into a preheated crucible. The preheat temperature should prevent freezing or clogging of the orifice passage 30 during the initial casting operation, and the temperature of the flowin~
metal should thereafter keep the crucible 22 and curvilinear el~ment 24 formin~ the nozzle at sufficient temperature to in~ure uninterrupted molten m~tal flow through the orifice passage 30. In certain applications, the curvilinear element 24 may be externally heated throughout the casting operation~ Also, the metal which is fed to the crucible 22 ~ay be superh~ated to allow a certain degree of te~perature loss without adversely affecting ~etal flow through the orifice passage 30~

Also, a metallostatic head height in the tundish 22 ~hould be maintained at a relatively constant level, typically ~t less than ten inches above the orlfice passage 30, ~hroughout the casting operation to assure that a rel~tively constant ~tatic head pressure ~ay be ~alrltained ~t the oriPlce passage 30. Thls may be ~ccomplished by initially pouring the ~olten metal 20 lnto the crucible 22 1 to the desired height and thereafter controlling the rate at which ~dditlonal molten metal 20 is poured into the crucible ~2 to maintaln the deslres metallostatic head. It ~ understandable that the rate at wh~ch add~tional molten melal 20 is fed to the crucible 22 should be ln Rubstan~al conformity with the rate at which metal flows from the orif ice passage 30 onto the casting surface 14 in forming strip material 10. Maintenance of a relatively constant helght o metal in the crucible 22 assures that the molten metal flow pressure through the orifice passage 30 is maintained relatively constant so as not to adversely affect the castlng operat~on or the quality of the strip material 10. Alternatively, externally applied pressure may be employed to control the pressure at the orifice pa~sage 30.

Using a tundish or crucible 22 similar to ~hat shown in Figure 1, macle of a commercially available tundish material ava~lable un~er the trade name S~H~, a casting run was made on Type 304 stainle~ steel. The orifice p~ssage 30 at the base of the crucible was about 1.3 inches long by 0.08 inch wide, and the distance, or gap, between the outer, lip projecting surface 38 and casting surface 14 was between 0~02 to 0.04 ~nch. With the speed of a rotating water cooled copper alloy drum held at about 930 feet per minute, molten ~etal was poured ~nto ~he crucible 22 at a tempera~ur~ of ~bou~ 2,900F es~ima~ed wi~h the use of an optical pyrometer. A metallostatic head he~ght of ~pprox~mately æix inches was mainta~ned throughvut the casting op~rat.~on. The str~p produced thereby was about ~ r~ c~

~ ~08~3 1 0.006 to 00008 inch thick and exhibited fairly good ~uality in that it was tough and ductile as cast.

During casting of strip material, the tendency of the strip 10 to adhere to the casting surface 14 for a significant distance, such as several eet or more, beyond the initial casting point 16 has been observed~ It is understandable that if the strip ~aterial 10 remains on a rota~ing casting dru~ or wheel 12 for a full revolution, damage to the crucible 22, particularly to the orifice passage 30 in the curvilinear element 24, could result. It has been found that the use of a doctor blade, such as a knife type element riding at or near the drum surface 14, approxlmately 2.5 to 6 feet from the orifice easily counters such adherence. With such an arrangement, ~he cast strip lS may be removed from the drum 12 by such doctor blade. Such doctor blade has been found particularly useful in the production of thinner amorphous strlp materials which appear to have a greater tendency to adhere to the casting surface 14 than do the crys~alline strip ~aterials. It is believed that the force which retains the strip on the casting surface may reflect the quality of ~he thermal contact b~tween the strip 10 and the casting surface 14.
Alternative arran~ements, such as an air knife, may also be employed to s~parate the strip 10 from th2 wheel 12.

~5 The casting of relatively high quality strip material including ~morphous material, which for the purpose o this invention incl~des materials which are ~ least 25%
~morphous, is feasible and practical using the apparatus and proc~dures described above. Understandably~ ~he quench ~ 1~0873 rates must be h~gher for amorphous material as compared 'co 6imilar gage crystalline strip material. Quench rates may be accelerated such as by lncre~s~ng the speed of the casting surface 14~ or the l~ke. It is ~mportant to recognize that the process may be conducted ~n two effective modes.
With the orifice passage 30 quite close to the casting surface 14 as measured between the outer lip projecting surface 38 and the casting surface 14, ~trip perhaps 0. 001 to 0.003 ~nch thick can be cast of either amorphous or crystalline materials. If the outer ].ip projecting surface 38 of the firs~ side portion 32 of the curvilinear element 24 is disposed further away from the casting surfa~e 14, and as casting surface speeds are reduced, strlp perhaps 0.005 to 0.050 inch th~ck can be ca.st. In this later mode, the quench rate may be significantly lower due at least in part to the ~ncrease ~n the product thickness.

Whereas the preferred embodiment ~as been described above for the purposes of illustration, it will be apparent to those sk~lled in the art tha~ numerous variations of the details may be made wlthout departing from the lnvention ~

I ela~m:

Claims (23)

1. An apparatus for continuously casting metal strip comprising:

a tundish for receiving and holding molten metal, a nozzle comprising a curvilinear element disposed in the tundish, said curvilinear element having an orifice passage therein, with the longitudinal extent of the orifice passage approximating the width of the strip to be cast, said orifice passage having substantially uniform cross-sectional dimensions throughout the longitudinal extent thereof, a cooled casting surface at least as wide as the strip to be cast, disposed at a standoff distance of less than .120 inch from the nozzle, movable past the orifice passage in a direction substantially perpendicular to the longitudinal axis of the orifice passage, said orifice passage defined between a first side portion and a second side portion of the curvilinear element.
2. An apparatus as set forth yin claim 1 wherein:

said first side portion has a substantially planar inside surface with respect to the orifice passage, and an outer, lip projecting surface at the discharge end of the orifice passage disposed toward, and facing the casting surface for a length of at least .01 inch before the outer, lip projecting surface of the first side portion is relieved to define a lip projection.
3. An apparatus as set forth in claim 1 wherein:

said second side portion has a substantially planar inside surface substantially parallel to and facing the inside surface of the first side portion at least at a lower portion of said orifice passage, and a bottom surface disposed toward, and facing the casting surface.
4. An apparatus as set forth in claim 1 wherein the orifice passage is substantially centrally located in the curvilinear element.
5. An apparatus as set forth in claim 1 wherein the casting surface is movable past the nozzle at a rate of from about 200 to about 10,000 linear surface feet per minute.
6. An apparatus as set forth in claim 1 wherein the casting surface is movable past the nozzle at a rate of from about 1/800 to about 4,000 linear surface feet per minute,
7. An apparatus as set forth in claim 3 wherein an inside portion of the orifice passage defined between the inside surface of the first side portion and the inside surface of the second side portion tapers inwardly from the molten metal holding portion of the nozzle to the location where said inside surfaces are parallel to one another.
8. An apparatus as set forth in claim 1 wherein the standoff distance between the outer, lip projecting surface and the casting surface is less than about 0.080 inch.
9. An apparatus as set forth in claim 1 wherein the outer, lip projecting surface extends for a length of at least 0.02 inch before the projecting surface is relieved to define the lip projection.
10. An apparatus as set forth in claim 1 wherein an integral curvilinear surface is provided between the inside surface of the first side portion and the outer, lip projecting surface of the first side portion.
11. An apparatus as set forth in claim 1 wherein a standoff distance of less than about 0.080 inch is maintained between the bottom surface of the second side portion surface and the casting surface.
12. An apparatus as set forth in claim 1 wherein the casting surface comprises the peripheral surface of a water cooled wheel.
13. An apparatus as set forth in claim 1, wherein the wheel is made of a metal selected from the group consisting of copper, copper alloy, aluminum, aluminum alloy, steel, molybdenum and combinations thereof.
14. An apparatus as set forth in claim 2 wherein at least a portion of the outer, lip projecting surface is in complete parallelism with the casting surface therebelow.
15. An apparatus as set forth in claim 3 wherein at least a portion of the bottom surface of the second side portion is in complete parallelism with the casting surface therebelow.
16. An apparatus as set forth in claim 1 wherein the distance between the casting surface and the parallel, facing outer, lip projecting surface of the first side portion is less than about 0.025 inch.
17. An apparatus as set forth in claim 1 wherein the distance between the casting surface and the parallel, facing outer lip projecting surface of the first side portion is less than about 0.010 inch.
18. An apparatus as set forth in claim 1 wherein the distance between the casting surface and the parallel, facing outer lip projecting surface of the first side portion is from about 0.003 to 0.006 inch.
19. An apparatus as set forth in claim 1 wherein the distance between the parallel facing inside surfaces defining at least an outer portion of the orifice passage is from about 0.010 to 0.035 inch.
20. An apparatus as set forth in claim 1 wherein A standoff distance of less than about 0.002 inch is maintained between the bottom surface of the second side portion and the casting surface.
21, An apparatus as set forth in claim 1 wherein the inside surfaces defining the orifice passage are disposed toward the casting surface at an angle of less than 90°.
22. An apparatus as set forth in claim 1 wherein the inside surfaces defining the orifice passage are disposed toward the casting surface at an angle of about 45°.
23. An apparatus as set forth in claim 1 wherein the curvilinear element is constructed of a material selected from the group consisting of graphite, alumina graphite, clay graphite, quartz, fiberized kaolin, boron nitride, silicon nitride, silicon carbide, boron carbide, alumina, zirconia, stabilized zirconia silicate, magnesia and combinations thereof.
CA000377164A 1980-05-09 1981-05-08 Strip casting apparatus Expired CA1180873A (en)

Applications Claiming Priority (2)

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US14842180A 1980-05-09 1980-05-09
US148,421 1980-05-09

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EP (1) EP0040069B1 (en)
JP (1) JPS574361A (en)
KR (1) KR830005942A (en)
AT (1) AT389252B (en)
AU (1) AU542805B2 (en)
BG (1) BG45213A3 (en)
BR (1) BR8102821A (en)
CA (1) CA1180873A (en)
DE (1) DE3165199D1 (en)
ES (1) ES8303951A1 (en)
HU (1) HU180410B (en)
MX (1) MX155278A (en)
NO (1) NO158049C (en)
PL (1) PL133112B1 (en)
RO (1) RO84488B (en)
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YU (1) YU43228B (en)

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EP0111728A3 (en) * 1982-11-12 1985-04-03 Concast Standard Ag Method of and device for producing products in the shape of strips or foils
GB2134428B (en) * 1983-02-03 1987-06-17 Metal Box Plc Continuous extrusion of metals

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US4142571A (en) * 1976-10-22 1979-03-06 Allied Chemical Corporation Continuous casting method for metallic strips
DE2856795C2 (en) * 1977-12-30 1984-12-06 Noboru Prof. Sendai Tsuya Use of molten steel for a method of continuously casting a thin strip
JPS5847939B2 (en) * 1979-01-02 1983-10-25 アライド・コ−ポレ−ション Method and apparatus for casting homogeneous vitreous filaments of metal alloys

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RO84488A (en) 1984-06-21
JPS574361A (en) 1982-01-09
SU1386020A3 (en) 1988-03-30
DE3165199D1 (en) 1984-09-06
KR830005942A (en) 1983-09-14
YU96081A (en) 1987-12-31
JPH0428464B2 (en) 1992-05-14
EP0040069A1 (en) 1981-11-18
AT389252B (en) 1989-11-10
AU542805B2 (en) 1985-03-14
BR8102821A (en) 1982-02-02
YU43228B (en) 1989-06-30
HU180410B (en) 1983-03-28
PL231050A1 (en) 1982-02-01
EP0040069B1 (en) 1984-08-01
ES502048A0 (en) 1983-03-01
PL133112B1 (en) 1985-05-31
MX155278A (en) 1988-02-12
NO158049B (en) 1988-03-28
BG45213A3 (en) 1989-04-14
ES8303951A1 (en) 1983-03-01
NO158049C (en) 1988-07-06
RO84488B (en) 1984-08-30
ATA205281A (en) 1989-04-15
NO811574L (en) 1981-11-10
AU6997881A (en) 1981-11-12

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