US3022552A

US3022552A - Continuous casting apparatus

Info

Publication number: US3022552A
Application number: US835634A
Authority: US
Inventors: Alfred H Tessmann
Original assignee: Individual
Current assignee: Individual
Priority date: 1959-08-24
Filing date: 1959-08-24
Publication date: 1962-02-27
Anticipated expiration: 1979-02-27

Description

Feb. 27, 1962 A. H. TESSMANN CONTINUOUS CASTING APPARATUS 3 Sheets-Sheet 1 Filed Aug. 24, 1959 INVENTOR wah) ./Zo megs Alfred J1. 7kg/nam yazfw@ Feb. 27, 1962 A. H. TEssMANN CONTINUOUS CASTING APPARATUS Filed Aug. 24, 1959 3 Sheets-Sheet 2 INVENTOR. T

Us ESS ESSmaZZ Feb. 27, 1962 A. H. TESSMANN 3,022,552

CONTINUOUS CASTING APPARATUS Filed Aug. 24, 1959 4 5 Sheets-Sheet 3 Lui-:1':

it Q/ JNVENToR. Z/'ed Tessmanrz.

BY Y 54 ma 19a/:MAL FIG 5 55 M United States Patent 3,022,552 CQNTINUGUS CASTING APPARATUS Alfred H. Tessmann, Chattanooga, Tenn. Filed Ang. 24, 1959, Ser. No. 835,634 11 Claims. (Cl. 22-57.2)

This invention relates to apparatus for the continuous casting of metals, including apparatus which is adapted to the production of hollow sections, such as tubes and hollow ingots.

In some respects, the methods and apparatus disclosed herein are related to those disclosed and claimed in my United States Letters Patent No. 2,837,791 issued lune 10, 1958, for Method and Apparatus for Continuous Casting.

One general object of this invention is to provide apparatus for the eiicient and substantially continuous casting of metal in formshaving hollow sections.

As -another object, my invention has within its purview the provision of apparatus having cooled inner and outer molds for the substantially continuous casting of metal in hollow sectional forms, kand wherein the inner mold is coextensive with the outer mold for a portion of the length of the outer mold which is suiiicient to insure the formation of a substantial inner retaining shell of solidied metal near the end of the mold at which molten metal enters.

Another object of the invention is to provide apparatus of the type described :for the substantially continuous casting of hollow met-al sections, which apparatus embodies means affording conditions effective at both the outer and inner surfaces of the metal being cast for improving the quality and surface finish of the cast metal produced thereby.

My invention further comprehends the provision of casting apparatus having inner and outer molds for the substantially continuous production of hollow sections and wherein heat is removed from the metal along both the inner and outer surfaces by a ow of atmosphere longitudinally of the inner and outer molds.

It is another `object of this invention to provide apparatus for the' substantially continuous casting of metal in hollow sectional forms and utilizing inner and outer molds together with means for lubricating the surfaces of both molds' and effecting the flow of lubricant longitudinally of the molds from the inlet to -the outlet lends sion of apparatus embodying inner and outer molds for.

the substantially continuous casting of metal in hollow sectional forms and including means for effecting areduction of the atmospheric pressure at the discharge end of the inner mold to an extent suiiicient to eiect the ilow of atmosphere along the inner mold between the metal and the mold.

As another object, my invention comprehends the provision of -apparatus including a seal within a hollow casting mold and which is effective for use in connection with suitable pumping apparatus `for effecting a reduction of atmospheric pressure and movement of atmosphere longitudinally of the mold between the mold and the metal being cast.

It is another object of this invention to provide apparatus for the substantially continuous casting'of met-al in hollow section, and which embodies means for eiecting drainage of molten metal from the parts and conduits which feed molten metal to the mold when the supply of metal'to the mold is stopped.

For effecting the accomplishment of the foregoing and other objects and advantages of this invention and to provide a deiinite example of a structure embodying and ICC characterizing apparatus which affords an illustrative example of this invention, I have developed and disclosed the structure herein illustrated yand described. Without making detailed reference to the accompanying drawings, it is lirst -to be understood that the continuous casting of metals comprehends the uninterrupted flow of molten metalunder pressure to one end of a casting mold, wherein the removal of heat from the metal effects the solidification thereof during the passage of the metal through the mold in which it is formed into -a desired sectional shape. Before the metal leaves the shape determining mold, it is essential that a solidified outer shell shall be vformed which has a thickness at least suiiicient -to continue its movement without material change of shape and withstand the hydrostatic pressure of any molten metal within the solidied outer shell.

Certain operating features and details of structure and arrangement of the disclosed apparatus are provided, not only to effect the continuous formation of Amolten metal into a casting of hollow section, but Ialso to afford good surface finish, high quality and desirable crystal structure inthe cast metal and freedom from porosity, as well as to accomplish the casting operation at a relatively high rate." As herein depicted, a supply of molten metal flows by gravity from va source, such as a holding furnace, through a nozzle to a cavity between inner and outer casting molds having mold surfaces in spaced and opposed rela tionship to one another. The inner mold is coextensive with the outer mold for a distance sufficient to accom plish its shape determining purpose and to insure the formation of an inner shell of solidified metal of suiiicient thicknessv to withstand the hydrostatic pressure of anyA molten metal which may remain within the cast piece beyond the end of that inner mold, while the outer mold extends beyond the inner mold for effecting the addi Lubricant issup'plied at metered rates to the surfaces of thenozzle and thence tothe mold surfaces. the disclosed apparatus, the diiferential in atmospheric pres sure betweenA the inlet and discharge ends of the molds is suicient to elect the ow of atmosphere between the cast metal and the mold surfaces and along the nozzle surfaces, thereby to induce the ow of lubricant longitudinally of the nozzle surfaces and mold surfaces. This movement of atmosphere not only eiects the withdrawal of gases from the molten metal and from the vaporiza` tion of'lubricant, but also prevents the formation of 1 static atmospheric barrier between the metal and theV mold surfaces and elfects the removal of both heat and A For effecting the stoppage of the' carbonized lubricant. casting operation for any reason without having metal solidify in the supply conduits and nozzle passages, av removable drain plug is provided at the bottom of the nozzle to. provide for the drainage of metal therefrom as p a supplement to the use of a valve for stopping the ow from the holding furnace.

Other objects and advantages of the invention will bev Yor vertically Adisposed apparatus.

' stantially as indicated by a line 3-'2-3 and accompanying arrows in FIG. 2;

FIG. 4 is a fragmentary end sectional view taken 'sub-r stantially at the `position indicated by a line 4:4 in I-iIG.`

2 and in the direction of the accompanying arrows;.and FIG. 5 is a fragmentary side sectionalview similar to FIG. 2, but illustrating a different portion of the apparatus of-FIGfil. Y

Having detailed reference to the drawings, wherein an exemplaryfer'nbodinient cf the invention is shown vfor illustrative purposes, the continuous `casting apparatus 1 herein illustrated is adapted to horizontal disposition,

although the invention comprehends either horizontally As depicted inY FIG. 1, an outer mold assembly is secured to a baserstructure 1-2 byY supports v13. YIn aligned relationship tothe outer mold assembly 1K0 and at one end thereof, a nozzle and inner mold assemblyl is secured to the base structure -12 and supported 'relative thereto by supports 15. In

solidies and emergesrtherefrom as a continuous cast` piece '1 8 of 4adesired hollowV section. `\l"\ithdrawing rolls 19V-driven by a prime mover, lsuch as a motor 20v through .wreed @Page nieuwe 22 .andownnecred driving Vparts'ncrludirxg elements such as sprockets 23 and24 and a driving chain 25 aidin effecting the withdrawal of the cast` piecewfrorn the casting apparatus; thevspeed of the wlthd'rawing rolls being selected to effect the movement of cast piece from the casting apparatus at a predefftiildfefev The holding furnace ,16 'has internal reservoir 26 li'n'ed Vlvitha suitable refractory material 27V and has 'insulated walls 28 housed within a suitable retaining wall structurel?. A passage 30 through refractory materialk VElZJ'ext'ends from one end of the reservoirtr26 to 'the ex*- ter'i'r of the holding ffrnface wall and -is there adjoined by the 'conduit `17 which has 'a refractory lining '33 and extends 'to a 'connecting conduits-1 jon a housing 35 'which gmprlses a part of the nozzle 'and inner mold assembly 'For erecting Aermite-l ofthe :new of molten nietl from therese'rvoir 26 of the holding furnace 1,6, 'a Vplug-'type valve 36 is mounted for nier/einen; rovi/ard and Yfrom the Y eind of ille passage 3u the 'holding furnace under tnefconfrol of a manuallyI operated yalveactu'ator 37. Y rn apparatus of 'the typelillustratel,l it is' desirable 'that the passage 30 and 'conduit`i17 'shall have a downward slope` from 'the interior of the nordingzrurneee to the Y iiozzle and inner moldfs'sembly 14. 'avoids 'the ,Y cap 59.

trapping of :any molten metal 'at 'a position lujivliieh it provides for lthe now of molten nietal away 'from the valve 36 'through the passage 30 and conduit 17 and 'toY` Ymight become -solidiaea 'and hamper new, and it also face of the outer mold tube which defines the exterior surface of a mold cavity and determines the exterior 1 face of the mold tube 39 and the inner surface of the outer jacket 38,Y through which coolant is circulated for cooling the mold tube during the operation of the apparatus. As shown in FIGS. 1 and 2, the coolant lflows to the space 47 through a conduit 48 near the inlet end of Y the mold and ows from the space vthrough a conduit 49 near the outlet end ofthe mold. Y

In order to provide desired heat conductivity in the mold tube 39, it is made of a highly heat conductive metal, such as copper with a wall thickness adequate to aiord the required strength. The inner surfaceY of this mold tube is reamed to a precise size and is'then plated witha highlywear resistant metal, such as chromium, and is then highly polishedtoV establish a very smooth and non-porous mold surface. Y

At 'the outlet or discharge endrof the outer mold assembly 10, as shown in FG. f5, the outer mold tube 39 fits into an opening 50 in an end closure plateSZ, which y closure lplate is also adjoinedtto the end of the outer jacket 3S. A gasket 53 provides a seal for the end 'of the coolant carrying spacing 47 and prevents the leakage of coolant therefrom adjacent the surfaces of the end cover plate 52. A housing 54 having a ygenerally cylindrical side wall 55 and an endrwarll 56 is secured to the end closure plate 52 and a gasket 57 provides a seal between the end wal-l 56 and the lend closure plate 52. An opening 58 is `provided in the end wall 56 of the housing in alignment with the opening 50 in vthe end plate 52 .for the passage of the cast piece 18 from the mold. At the endtof the side Wa1155 opposite the end Wall 56, an end Y cap 59 is secured to the side wall 55 in spaced 'and opposed relationship to the end wali 5-6. The end cap 59A has an opening 60 which is: aligned withV the opening Y SS for the passage `of the cast piece V13 therethrough.

Between `the lend 'cap 59 and the side wall l55 a part 62 is provided 'which includes 'a mounting ange portion 6?,` and an inwardly projecting and substantially frusto conicalbae 64, Vwhich baille, inV addition to projecting inwardly toward the end of the mold tube 39, is substantially concentric with respect to the openings 50 'and l60. The ange portion 63 ofthe part '62 is 'secured to the housing 54 between the outer Vend of vthe side wall Vv55 and the end cap 59, and a channel 65 in the 4'outer 'en'd surface of the part 62 extends around an opening 66 in the part 62 and provides 'a header passage E'c'ornrrlunicating with a plurality of `circumferentially spaced nozzle openings '67 which `*extend through the part 62 to the interior of the frusto-'conical baille 64.. The channel 65 is Vclosed by thefend cap 59, and coolant is supplied thereto through a pipe 68 which is threaded into 'an opening in the end Therinn'er endv of the frursto-conical Vbaille l624, in addition to 'extending 'toward the Voutlet end of the 'nlolel tube v'alve a6 is `closed atfthe holding rurnaee 'to 'stop the operation of the costing apparatus.

j Asjuiown in FIG. 2, the outer mold 'assembly ro in- Y eluaes'e mentar outer 'jacket :3s which serves both 'as a housing and support for a mold "tube 39 -and as vaY jacket for the Vcirculation 'of aV coolant liquid, such as water, Varound and` along 'the mold "tube 39 dlning 'the operation'df the apparatus. A't'its inlet end 40, as shown in'FG. 2, the outer mold tube v39'is secired'to the tubular 'outerjaclc'et 3S by a ri'rigtype end plate '42 havinga Y coller-type `flange 43 thereon which Yis 'threadedfinto an internal recess 44 in Vthe nletfend of the outer mold beingY in'substantiallyrflush relationship to an ifnlerur- A conduit 69 'is secured to yand communicates with the Y upper portion of the side Wall'55 of 'the'housing 54 `and is connected 'toa vacuum 'pump (not shown) 'for reducing the pressure at the outlet end ofthe mold tube 39 and within the housing 54 to a value well -below normal atmospheric pressure.Y The `coolant and the coolant vapors whchfa're caused Al-fythe contact of the 'coolant 'with the cast metal within the baflie 64 are withdrawn from the interior of the housing 54 through the conduit 69 and are separated from the atmosphere in the vacuum. line. This avoids the escape of coolant and vapors through the

openings

53 and 66 at the end of the housing 54. The reduced pressure within the housing 54 also, in addition to preventing the movement of coolant into the outlet end of the mold tube 39 between the cast metal and the mold, eiects a movement of atmosphere longitudinally of the mold tube 39 between the metal and the mold from the inlet end of the mold tube 39.

in the nozzle and inner mold assembly, as illustrated in FiG. 2, an inner mold assembly 70 extends through the interior of a nozzle 72 to a position well within the inlet end of the mold cavity of the outer mold tube 39 for defining the inner surface of the cast piece 1S of hollow section. This inner mold assembly 70, in addition to being supporte with the nozzle 72, at the inlet end of the outer mold, also has a projecting outer end portion 73 which is supported by one of the supports 15 at a position spaced from the nozzle. rihe outer end porltion of the inner mold includes an outer metal support tube 74 which is longitudinally straight and of uniform section, which outer metal support tube extends into a longitudinal inner opening in the nozzle 72 and there adjoins an inner metal mold tube 76 at a joint 77 providing snugly fitting overlapping portions on the ad ioined ends of the tube and from which the tubes extend in coaxial relationship to one another with their outer surfaces in-iiush relationship. The outer support tube 74 may be made of a rnetal such :as steel, while the inner metal mold tube 7d, like the outer mold tube 39, is made of a highly heat conductive metal such as copper plated on its exterior surface with a wear resistant metal such as chromium having a highly polished outer surface ground accurately to size to establish the proper wall thickness in the cast metal and provide a surface to which the metal will not adhere unduly during the casting operation.

At its inner end, the inner mold tube 76 adjoins a flared end 78 on an inner metal tube 79 which extends through the inner mold tube and outer metal support tube 74 in substantially coaxial and concentric relationship thereto. The inner metal tube 79 has an opening 3o which extends longitudinally therethrough from end to end.

Between the inner metal tube 79 and the outer metal support tube 74, a metal tube S2 extends from the outer end of the inner metal tube 79 to a position within the inner mold tube 76 and near the flared end portion 7S of the inner metal tube. As shown in FIGS. 3 and 4, the metal tube S2 has peripherally spaced metal ribs 33 extendin'J longitudinally of the outer surface thereof, which ribs engage the inner surface of the outer support tube 74 and the inner surface of the inner mold tube 76 to aord support between the adjacent tubes and to provide passages therebetween for the ow of coolant to the inner surface of the inner mold tube 76. Similarly, the inner metal tube 79 has peripherally spaced ribs 84 extending longitudinally thereof and engaging the inner surface of the metal tube 82 to provide supporting spacers therebetween While leaving passages for the ow of coolant from the inner end of the inner mold tube '76 to the outer end of the inner mold assembly. A cap 85 is threaded onto the outer end of the outer support tube 74 and has threaded engagement with the inner metal tube 79, as shown in FlG. 9, as Well as having a groove S therein for supporting the outer end of the metal tube 32. Passages 87 extend through the cap 85 and communicate with the space between the metal tube 82 and the outer support tube 74 for making connections to a suitable source of a liquid coolant, such as water, to supply such coolant to the inner surface of the mold tube 76. Passages 88 in the cap 85 communicate with the space between the inner metal tube 79 and the metal tube 32 to provide for the flow of coolant from the inner mold assembly.

A pipe S9 extends through a central opening in the cap and extends through the longitudinal opening S0 in the inner metal tube 79 to a position beyond the inner end of the inner mold Vtube 76 and the ilared end portion 7S on the inner metal tube. At its inner end and in spaced relationship to the inner end of the inner mold tube and the flared end portion 78 of the inner metal tube, the pipe 89 has a disc 9i) of a wear and heat resistant material and a supporting metal disc 92 secured thereto in spaced and opposed relationship to the flared end portion 78 of the inner metal tube; the diameter or peripheral size of the disc being only slightly smaller than the normal inside dimension or dimensions of the holle-w portion of the cast piece 1S. Also secured to the inner end of the pipe S9 adjacent the surface of the disc 9i? which is opposite the inner mold tube 76 is a hollow housing 93, the interior of which is in communication with the interior of the pipe 89 and which has therein a plurality of peripherally spaced openings 94 for directing liquid coolant, such as water conducted thereto through the pipe S9 to the peripheral surface of the disc 961. The discs 96 and 92 and the housing 93 are secured in place on the pipe 89 by means such as a nut 95 and an end closure cap 9d for the pipe S9.

A coolant liquid, such as water, is supplied to the pipe 89 through a projecting end 97 thereof which is exterior' to the cap S5 at the outer end of the inner mold assembly '7(l. Also, passages such as 9S are provided in the cap 85 at the outer end of the inner mold assembly for connection to a vacuum pump, so that the inner metal tube 79 serves as a conduit for obtaining sub-normal atmospheric pressure at the discharge end of the inner mold tube, while the disc 90 and the coolant supplied thereto through the pipe 89 and housing 93 serve as an effective seal within the cast metal piece at the position spaced from the end of the inner mold. rihe pressure reduction at the inner end of the inner mold is suiiicient to exhaust the liquid cooiant and vapor from around the disc 9u and also to effect the movement of atmosphere and vapors longitudinally of the inner mold assembly between the mold and the metal being cast. This flow of atmosphere along the mold not only cools the metal and removes vapor and gases therefrom, but also prevents the movement of any moisture from theregion of the seal,

to the space between the inner mold and the metal being cast.

4 At the outer end of the inner mold assembly 70, a hanged bearing 99 fits into an opening 1li@ in the sup port l5 and is held in place by an end plate 102 which is secured to the support 15' by fastening means, such as cap screws 3.03. A shim T164 is used in the disclosedy structure between the outer surface of the outer support tube 74 and an opening 195 in the bearing 99 to insure accurate positioning and film support for the outer end of the inner mold assembly.

The nozzle 72 constitutes an assembly of parts encompassing the midportion of the inner mold assembly and which has a portion extending into the cavity of the outer mold for conducting molten metal from a source, such as the holding furnace l5 to the space between the inner mold tube 76 and the outer mold tube 39. That space between the inner and outer mold tubes, of course, de-

fines the sectional shape and dimensions of the hollow longitudinal mid-portion of the housing 35.

metal and the cooling effected by the ow of coolant through the inner mold assembly, as well as the cooling vaccomplished by the ow of atmosphere between the cast metal and theV molds, and also the cooling erfected by the coolant which is used for sealing purposes at a position spaced from the discharge end of the inner mold. Considering.thestructure'of the nozzle 72,Y as shown idF-IGS. 2, 3 and 4, the housing;35 is of generally `cylindrical structure, having an outer wall 106 andV end `walls 167 and 1%. The conduit 34 adjoins and extends fromtherupper portion of the outer wail 165 for maliing connection to the conduit 17 through which molten metal is conducted to the nozzle 'from the holding furnace or other source or" supply. A tubular metal inner shelly 109 having an outwardly projecting flange 11% at its outer end extends through aligned openings 112 and 113 in'theend walls 1137 and 163 of the housing 35; the tubular portion of the shell fitting snugly into the opening 112 in the Vend wall1il7 and extending through the opening 113 in spaced relationship tothe end wall 1138 to a position such that it projects beyond the end wall 1&3, while the ange 114i engages the outer surface of the end wall 15117.Y This tubular metal shell 109 is secured in place relative to the end wall 107 by a removable cov-,.

ering plate 114 having a recess 115 therein which fits over Y t the ange 11G and is secured to the end wall 107 by 'l fastening means such as cap screws 116.

An outer tubular metal shell 117 has an outwardly projecting ilange 11S thereon and is secured tothe end wall 168 by Ia hanged holding ring 119 held in place against'the end Wall 193 by fastening means, such as cap Y screws 129. The inner opening of the Youter metal shell Y 117 'is substantially equal in size to the size of the opening V113m rthe end wall 10S. Also, the lengths of theV .inner metal shell 1119' and the outer metalV shell 117 are such that in addition to 4being disposed in substantially coaxial and concentric relationships to one another, the

' ends the shells remote from Vthe housing V35 terminate in substantially coplanar relationship to one another and deine the exterior surfaces ofY a ring-type nozzle portion Vil'22which extends into the cavity Vofthe outer mold tube Y inv closely spaced relationship thereto, as well as encoming 123 of a heat'insulating refractory material 'is provided has a Yplurality of circumferentially spaced and axially extending openings 124 therein which extend to and open into-the space between the inner andouter mold tubes from acircumferential header passage 125 which encompasses the inner mold assembly 70 at the The remainder of the housing 35 and the conduit 34 are lined` with a heat insulating refractory material 126 which has a'passage 127 therein alfording communication between the header passage 125 and thepassage 36. in the conduit 1'7. To provide for a downward flow of molten metal assembly, a brace extends between the lower portions of the supports 15V and is securedthereto by Vfastening means, such as cap screws 1.37.' Also, a top brace 133V Vor 7o, provision is made for the supply of a metered :piantity of lubricant to the surfaces of each of the mold tubes from lthe spaces between each moldtube surface and the nozzle 72. For supplying the lubricant to the inner surface of the outer mold `tube 39, a conduit 14) is threaded into theV edge of the ring-type end plate i2 and communicates with a passage'142 inthe endV plate .for the flow of lubricant to a peripheral groove 143 in the inner surface of the end plate, whiclrgroove encompasses the outer shell 117 of the nozzle. The leakage of lubricant between lthe nozzle and the outer endof the end plated?. is prevented by a gasketV 144 secured in place between the groove 143 and theV outer surface of the end plate by a retaining ring 1445. From the' conduit '140 and passages 142, lubricant flows aroundy the nozzle in the groove 143 and then moves longitudinally of the inner surface of the mold in the space'between the nozzle and the'mold tube and then moves along the mold surface between the metal and the mold as a result of the reduction of the atmospheric pressure-'at the outlet end ofthe mold. Y Y i For providing a metered Vquantity of lubricant to the fouter surface of the inner mold ltube 76, lubricant is- V. supplied through a conduit laid which is threaded into an edge of an end place 147 and llows through aV passage 48 in the end plate 147 to a groove 143 the inner edge surface of the end plate 147, which latter groove encompassesthe outer surface of the outer support tube 74. Leakage of lubricant past the outer end surface of the end plate 147 is prevented by a gasket 149 held in piace between the end plate and the outer support tube by a ring 153 secured to the end surface of the end support plate 147. From the conduit 146 'and passage 14S, lubricant llows around the outer surface of the outer support tube 74 in the groove 143, and then flows between Y cation betweenthe inner mold tube and the metal Vbeing Y cast; the ilow of lubricant being induced by thereduction from the supplyV in the holding furnace toy the header passage 125, for supplying molten metal to the mold Ycavity under a. head pressure, the passage 127 is located at the top portion of the housing 35. Y

For effecting the. drainage of molten metall from the nozzle passages 124, the'header passage 125 and the metal feed passages 127 and 30,11 removable plug 12S is provided at Ithe bottom portion of the housing 35 and includes a cap portion 129 to Vwhichis secured a refractory plug element 130 for closing artapered'opening 132 in ythe lower portion of the refractory lining 126 in the 'housing 35, which opening 132 communicates with the of atmospheric pressure at the discharge end of the inner mold tube; Y Y

To start the operation of the vdisclosed apparatus, -a metal piece having the sectional shape of the metal to lbe cas-t and a length sufficient to extend from the withdrawing rolls Y19 to a position lbetween the inner and uter mold tubes near the discharge end of the nozzle 72 is placed in the lmold cavity and'in engagement with the withdrawing rolls. This piece is desirably threaded on its end, sothat it can be detached from the cast metal by unscrewingV it therefrom after the casting operation is underway. With'the ystarting piece in place, the flow of coolant to the inner and outer molds and tothe vacuum seals for the inner and outer molds is started. Also,'the metered ow of lubricant is started through'conduits 140 and 146, and the vacuum pumps are turned on for effecting'the reductions of air pressure at the discharge ends of the inner and outer molds so'that the vmolds are cooled and lubricated andV the reduced atmospheric pressures at the discharge ends of both the inner and outer molds are eifective Afrom the commencement of the operation thereof. Then, with the plug 128 in place, the flow of molten metal is started -by opening the Vvalve 36 at the holding furnace. The ilow of ymetal and the continuous Vcasting aigle-tal in a hollow sectional shape-may be continued for any desired period of time. When the cast metal has reached the withdrawing rolls and is being withdrawn 9 thereby at a predetermined rate, the starting piece is disconnected from the cast metal for another use in starting the operation of the apparatus.

During the continuous casting of metal, the reduced atmospheric pressure within the housing 54 eects the Y movement of lubricant and atmosphere longitudinally of the inner surface of the outermold tube 39 between the metal and the mold, and atmosphere, vapors and gases from the metal and lubricant, as well as carbonized lubricant and the vaporized coolant sprayed on the outer sur-face of the cast metal for cooling and sealing purposes within the housing I54 are removed by the action of the vacuum pump through the conduit 69. A considerable amount of heat is removed by the air and atmosphere which moves through the mold as a result of the reduced pressure at the outlet end thereof and the removal of vapors and gases from the metal, as it is cast, improves the quality of lthe cast metal and aids in eliminating surface indentations and internal blow holes in the cast metal. t

Similar functions are accomplished by the reduction of pressure and cooling which is effected by the reduction of the atmospheric pressure at the discharge end of the inner mold and between the inner mold and the seal provided by the disc 9i) and the coolant which is applied to the surface thereof for cooling and sealing purposes. Since the inner and outer molds are both cooled by a iiow of coolant and that cooling is yaided by the movements of air and atmosphere along the molds, as well as by the coolant applied directly to the inner and cuter surfaces of the cast piece adjacent the discharge ends of the molds, the casting rate may be relatively high and internal structure and grain of the cast metal afford t igh quality in the cast piece. Furthermore, the finish of both the inner and outer surfaces of the cast metal is smooth and devoid of scale.

Vwnen the operation of the apparatus is to be stopped for any reason, the valve 35 at the holding furnace is closed, and the plug 128 at the bottom of the housing 35 is promptly removed, so that the molten metal from within the passages 30 and 127,A as well as from the nozzle passages 12d and the header passage 125 flows outwardly through the opening 132 without solidifying in the passages. The operation of the withdrawing rolls :i9 is continued until the end of the cast piece is removed from the mold cavity, after which the various coolant supplies7 the vacuum pumps and the lubricant are shut ofi.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

l. In apparatus for the substantially continuous casting of metal in the form or" a hollow section having inner and outer surfaces, the combination comprising an outer rnetal mold having an opening therethrough which de- :fines the outer `surface of amold cavity having inlet and outlet ends7 a metal inner mold extending into the inlet end of said mold cavity in the outer mold and having an outer mold surface in spaced and opposed relationship to said surface of the outer mold, said inner mold terminating at an inner end wit-hin the mold cavity in the outer mold, a ring-type nozzle encompassing the inner mold and lhaving a portion extending into the inlet end of the mold cavity, said nozzle having inner and outer surfaces in closely spaced relationship to portions of said surfaces of the inner and outer molds and having a passage therein for the ow of molten metal to the mold cavity, means for cooling the molds, means providing an effective closure for the hollow section of cast metal and an effective seal with the inner surface thereof at a position within the outer mold and spaced from the inner end of the inner mold, and means for eecting a reduction of the atmospheric pressure to a value below normal atmospheric pressure within the space between the inner mold and the closure providing means.

2. In apparatus for the substantially continuous casting of metal as defined in claim 1, said means for cooling the inner mold including passages in the inner moldfor the iiow of coolant longitudinally of the inner mold toward and from the inner end thereof.

3. ln apparatus for the substantially continuous casting of 4metal as dened in claim 1, said inner mold having an opening extending longitudinally therethrough, and means extending through said opening in the inner mold and serving as a support for the closure providing means.

4. In apparatus for the substantially continuous casting of metal as defined in claim 1, said passage in the ring-type nozzle for the flow of molten metal to the mold cavity including a header passage extending circumferentially of the nozzle, and a plurality of passages spaced circumferentially of the nozzle and extending longitu-y dinally thereof from the header passage through said portion which extends into the mold cavity.

5. In apparatus for the substantially continuous casting of metal as defined in claim l, the combination being further characterized by means for introducing lubricant between the nozzle and the inner mold at a position external to the mold cavity, means for effecting distribution of the lubricant peripherally of the surface of the inner rnold, and said reduction of atmospheric pressure in the space between the inner mold and the closure providing means effecting the flow of said lubricant longitudinally of the inner mold between the inner mold and the nozzle.

6. In apparatus for the substantially continuous casting of metal as defined in claim 3, said opening through the inner mold serving as a conduit for connection to the pressure reducing means, and said means extending through said opening comprising a conduit for the flow of liquid to the means providing an effective seal with the inner surface of the castmetal.

7. in apparatus for the substantially continuous casting of metal as defined in claim 4, said nozzle also having an openable and closeable passage therein for the drainage of molten metal from the header passage.

8. in apparatus for the substantially continuous casting of metal in the form of a hollow section having inner and outer surfaces, the combination comprising an outer mold having an opening therethrough which defines an outer mold surface having an inlet end for the introduction of molten metal and a discharge end for the ejection of solidified metal, an inner mold supported within the inlet end of the outer mold surface and having a mold surface in spaced and opposed relationship to said outer mold surface to define a mold cavity between the outer and inner molds, nozzle means extending into the mold cavity between the inner and outer molds at the inlet end of the outer mold surface, said nozzle having a passage therein for the ovv of molten metal into the mold cavity between the molds, said inner mold having an end at which solidified metal emerges, means for introducing lubricant to each of the mold surfaces between Le nozzle and each mold, and means including a conduit extending through the inner mold, a chamber at one end of the outer mold, and parts providing effective pressure seals with the metal being cast at positions spaced from one end of the inner mold and also within said chamber for effecting atmospheric pressure differentials between the ends of each of the molds which is sutiicient to move lubricant and atmosphere longitudinally of each mold toward the discharge end thereof.

9. In apparatus for the substantially continuous casting of metal to form a casting of hollow section, the cornbination comprising an outer metal moldy having an elongated opening therethrough which defines an outer mold surface and has an inlet end to which molten metal is supplied and an outlet end from which a solidified metal casting is ejected, a metal inner mold extending into the inlet end of said opening within said outer mold surface and having a mold surface in spaced and opposed relationship to said outer mold surface to define a mold cavity bespaanse tween the outer and inner molds, a ring-'type nozzle exand inner molds and having a passage therein for the ow of molten vmetairto the cavity between the molds,` means for supplying molten metal to said passage, means for cooling the inner and outer molds, means for introducing lubricant between the nozzle surfaces and the 'mold surfaces of eachV of the molds, and separate means for effecting reductions of the atmospheric pressures `at the. ends ofthe outer and inner molds remote from the nozzle to values -below normal atmospheric pressure, thereby to veect movementsrof the lubricant along the nozzle and between each mold surface and the metal being cast, saidmeans for effecting reduction of the atmospheric pressure at the end of the inner mold including means spaced from said end of theinner mold and providing a seal Within the hollow casting and a conduit extending' longitudinally through the inner mold. y

l0. In apparatus for the substantially continuous casting Vof metal in the formiof a hollow section having inner and outer surfaces, the combination comprising an outer mold having an opening therethrough which defines an outer mold surfaceV having an inlet end for theintroduction of molten metal and a discharge end for the ejection of solidified metal, an inner mold supported within the inlet end of the outer mold surface and Vhaving a mold surface in spaced and opposed relationshipto said outer mold surface to dei-ine a mold cavity between the outer and inner molds, a ring-type nozzle extending into the mold cavity and having surfaces in closely Yspaced relationship to said moldsurfaces of the inner and outer molds, said nozzie having a passage therein for thevow of molten metal'to the moldV cavity between the molds, means providing an eectire seal with the solidi-fied. inetd at a position spaced from the discharge end of the, inner mold, and means for eliecting a reduction of the atmospheric pressure lto a value below normal atmospheric pressure between the discharge end of the inner mold and the last mentioned means, said means providing an elective seal with the solidified metal comprising a metal plate mounted in a plane transverse to the mold surface of the inner mold and having its periphery in closely spaced relationship to the solidin'ed metal, and means for providing a flow of liquid to'thessurface of Vsaid metalv plate remote from'the inner mold and directed to Vthe peripheryof the vrnetal plate to provide -a liquid seal betweenthe periphery of the metal plate and the solidined metal. i Y.

ll. In apparatus for the'substantially continuous casting of metal 'to form a casting of hollow section, the combination comprising an outer metal mold having an elongatedV opening therethrough which donnes an outer mold surface and has an inlet end to which molten metal is supplied and an outlet end from which -a solidified metal casting emerges, a metal inner mold extending into the inlet end of said opening Within said outer mold surface and having a mold surface in spaced and opposed relationship to said surface of the outer mold to define a mold cavity between the outer and inner molds, a ring-type nozzle extending into the mold cavity at the inlet endk of-said opening land having outer and inner 20* surfaces'in closely spaced relationship to portionsV of said mold surfaces or" the outer and inner molds and having a passage therein for the ow of molten metal to the cavity betweenithe molds, means orsupplyingrmolten metal to said passage, means for cooling the inner and outer molds, said casting havinginnerand outerr surfaces produced by the spaced Ymold surfaces, and separate means including partsfproviding sealsV with the inner and outer surfaces ofthe casting and spaced from the Y ends of `the respective molds, and conduits extending to References Cited in the iile Vof this patent UNITED STATES EATENTS 1,223,676 De Lavand Apr'. 24, 1917 '2,837,791 Tessman Iune l0, 1958 '2,864,140 Morgenstern Dec. 16, 1958 'FGREIGN PATENTS y812,356

Great Britain Apr. v22, 1959