US3587711A - A method for continuously casting metal sheet or strip - Google Patents

Abstract

THE APPARATUS FOR PRACTICING THE PROCESS COMPRISES A ROTATABLE DRUM HAVING AN INTERNAL INVOLUTE METAL CASTING CHAMBER WHICH IS CENTER CHARGED FROM A CONTINUOUS SOURCE OF MOLTEN META, A WATER COOLING JACKET FOR THE CHAMBER TO EFFECT SOLIDIFICATION OF THE MOLTEN METAS AS IT TRAVELS ITS VOLUME PATH TO A DISCHARGE OPENING COMMUNICATING WITH THE CHAMBER, TOGETHER WITH APPARATUS EXTERNALLY LOCATED RELATIVE TO THE DRUM TO EFFECT A COOLING OF THE CAST METAL.

D R A W I N G

Description

United States Patent Inventor Appl. No. Filed Patented June 28, 1971 A METHOD FOR CONTINUOUSLY CASTING Primary Examiner-J. Spencer Overholser Assistant Examiner-R. Spencer Annear Attorney-Kimmel, Crowell and Weaver ABSTRACT: The apparatus for practicing the process comprises a rotatable drum having an internal involute metal casting chamber which is center charged from a continuous source of molten metal, a water cooling jacket for the chamber to effect solidification of the molten metal as it travels its volute path to a discharge opening communicating with the chamber, together with apparatus externally located relative to the drum to effect a cooling of the cast metal.

METAL SHEET 0R STRIP 10 Claims, 4 Drawing Figs.

US. Cl 164/83, 164/87 Int. Cl 822d 11/06 Field of Search 164/82, 84, 87, 89, 276, 281, 283, 289, 295, 297, 83; 18/12 A METHOD FOR CONTINUOUSLY CASTING METAL SHEET OR STRIP CROSS-REFERENCE TO RELATED APPLICATION This comprises a division of my copending patent application filed Sept. 7, 1967, Ser. No. 666,067, which issued May 12, 1970 as US. Pat. No. 3,5l 1,307, entitled APPARATUS FOR THE CONTINUOUS CASTING OF METAL SHEET OR STRIP."

BACKGROUND OF THE INVENTION This invention pertains to the general technological field of Metal Founding in those areas thereof which teach arts relating to methods for continuously casting molten metals and the apparatus by which such methods may be practiced.

The prior art is replete with references to the founding of metals, and of course, to the founding of ferrous metals, the subject matter of this invention. However, it has remained until most recent times that improvements have been made in the age-old art of casting steel which may be considered as being of prime importance to this art. Among these most recent advances comprise the introduction of the newly developed basic oxygen furnaces, and the relatively new art of continuously casting metals, particularly steel, and it is to this latter field that this invention is addressed.

To practice the teachings of the prior art on a commercially feasible scale has involved huge outlays ofmonies involving as it does, the necessary acquisition of large tracts of land and the erection of buildings and other types of edifices to house, for example, apparatus for the molds, stripping facilities, soaking pits to reheat ingots, blooming-slabbing mills, slab heating furnaces, hot strip-mills, et cetera. To the cost of acquiring the necessary land and erecting necessary buildings must be added the high cost of employing salaried engineers, technicians, and both skilled and unskilled mechanics which were essential to the practice of any modern founding operation of appreciable size.

As has been stated above, it is known that efforts have heretofore been made to continuously cast metals and steel, being a prime metal utilized in most fabrication problems, has received much attention but prior art efforts to make a satisfactory continuous casting have met with but little success.

Heretofore, and perhaps one of the most widely publicized developments in the continuing casting of metals comprises the vertical casting which was accomplished by pouring the molten metal vertically into a tundish and through a cold mold that shaped the metal into either strands, bars or slabs. The slabs so formed were subsequently cut to length, cooled, stored and later rolled into plate or strip. The most practical processes for casting continuous metal strip today comprises the pouring of molten metal around the exterior of a drum or between two horizontal endless belts. The practice of the prior art processes for continuously casting molten metal requires, therefore, an edifice of rather appreciable height and great ground areas for accommodating and treating the material after it has been cast.

This invention has, as one of its foremost objects, the simplification of the casting machine to the extent that its use will reduce the height of the equipment and the area required to carryout present practices with known casting machines. A further, but of no less prime importance as an object of this invention, is to provide a casting machine which casts metal strip directly into a hot coil thereby eliminating expensive floor space for rolling and preparation facilities required to reduce slabs into strip.

In the practice of this invention, it is one of the primary objects thereof to provide apparatus for continuously casting ferrous metals in sheet or strip metal form in accordance with specified thicknesses and widths and maintaining these dimensions within close tolerances, this being accomplished through the use of metal coil casting apparatus which occupies but a minimum of space and which requires but little.maintenance.

A further object of this invention is to provide apparatus and a process for continuously casting metal, wherein the continuous metal casting is achieved by passing the molten metal through an involute passage formed in a continuously rotating drum and effecting the cooling of the molten metal as it travels the passage whereby the metal emerges as a continuous strip.

A still further object of this invention is to provide a cooling medium and surface lubricant for the strip as it emerges from the casting drum whereby as the strip or'sheet is ejected from the casting drum or mold the temperature thereof is lowered which will cause some contraction which, in the absence of the cooling and lubricating medium could cause the adherence of adjacent convolutions, one to the other.

Still another object of this invention is to provide retracting elevator means below the cast coil to catch the leading edge of the strip (the skin having solidified) as it leaves the casting drum or mold and in so doing to serve in the dual roll of support means for the drum and cast metal and guide means for guiding the extruded strip of material through its convoluted path.

It is still another object of this invention to provide a peeler blade for separating the leading edge of the exterior wrap of the extruded metal strip end which also serves as guide means to lead the leading edge of the strip into conventional pinch rolls.

Other and further objects and advantages of the instant invention will become more manifest from a consideration of the drawings annexed hereto when read in the light of the immediately following appended specification.

APPARATUS With reference to the specification and to the drawings:

FIG. I is a side elevational view of a metal coil sheet or strip casting machine or device constructed in accordance with this invention;

FIG. 2 is an enlarged medial longitudinal cross-sectional view of the machine shown in FIG. 1;

FIG. 3 is an enlarged detail transverse cross-sectional view, FIG. 3 being taken substantially on the vertical plane of line 3-3 of FIG. 1, looking in the direction of the arrows; and

FIG. 4 is a cross-sectional view, partly in end elevation, FIG. 4 being taken on line 4-4 of FIG. 2, looking in the direction of the arrows.

Referring now more specifically to the drawings, reference numeral 10 designates, in general, a machine or device constructed in accordance with the teachings of this invention to effect the continuous coil casting of molten metals, and of steel in particular. The machine, device oi apparatus 10 is adapted to be housed in a suitable edifice (not shown) and is supported on means which in this instance are shown as comprising an inverted substantially U-shaped base 12. The base 12, as illustrated in the appended drawings, reference being made especially to FIGS. 1 and 2 thereof, is seen .to include a pair of horizontally elongated upright laterally spaced and substantially rectangular sidewalls l4, l6 and a normally horizontal elongated substantially rectangular bight or base wall 18 which spans the upper ends of the sidewalls l4, l6, and is fixedly secured thereon by conventional means. Set into the base 12 intermediate the opposed ends thereof and extending through an opening 19 formed in the bight wall 18 is a vertically elongated substantially hollow rectangular reservoirs 20 adapted to receive a liquid coolant 22 therein which is, preferably, a mixture of oil and water. The reservoir 20 comprises opposed pairs of upright side and end walls 24, 26, and 28, 29, respectively, the pairs of side and end walls each having upper end portions extending above the plane of the base wall 18 to serve a function to become obvious below.

At 30 is indicated a conventional hydraulic cylinder having an end thereof pivotally connected at 32 to upright standard means 34 carried on base wall 18 at a point remote from the reservoir 20 and at one side thereof. The other end of the hydraulic cylinder 30 is provided with the usual reciprocable piston rod 36 having its outer end pivotally connected at 38 to convention lug means 40 which project longitudinally from the adjacent upright end wall 42 of a horizontally elongated substantially hollow slide block 44.

The slide block 44 includes a normally horizontal slide plate 46 from an end of which arises the integrally formed end wall 42 (supra), and at the other end thereof is disposed an integrally formed second upright end wall 48 remotely positioned relative to the end wall 42 and which is substantially parallel with respect thereto. lnterposed between the end walls 42, 48 and in spaced parallel relationship with respect thereto is an intermediate upright wall 50. Extending transver sely across the upright outer lateral edges of the end walls 42. 48, and the related edges of the intermediate wall 50 are integrally connected sidewalls 52, 54.

The slide plate 46 of the slide block 44 is integrally connected at each of its opposed longitudinally extending sides, adjacent the lower marginal edges thereof, with an outwardly projecting tongue 56 (see FIG. 4), each of the tongues being slidably engageable in an adjacent substantially U-shaped groove 58. As is seen in the drawings, the grooves 58 are formed in longitudinally extending laterally spaced and parallel track members 60 integrally formed with the base plate 18 and project above the plane thereof.

To serve a purpose to be more specifically mentioned below, it is now evident that the sliding block 44 may be moved longitudinally of the base plate 18 to assume any preselected position thereover through the operation of hydraulic cylinder 30 all in the conventional and well-known manner.

Supported and secured on the upper ends of the end wall 48, the intermediate wall 50 and the sidewalls 52, 54, and extending therebetween is a horizontally elongated journal box 62. The journal box 62 is formed with an elongated bore 64 which extends therethrough to open in the plane of each end thereof, and each end of the journal box 62 is suitably counterbored at 68 and again at 68' to receive the sleeve bushings 70 therein coaxially aligned with the bore 64. An elongated cylindrical shaft 72 extends axially through the bore 64 and the opposed ends of the shaft are journaled and are supported for rotation in the bushings 70. One end of the shaft 72 terminates in an enlarged integrally formed first frustoconical centering and support head 74, and the shaft 72 and its head 74 are provided with a common coaxially extending bore 76 extending from end-to-end thereof.

As is clearly seen in FIG. 2, that end of the shaft 72 remotely disposed relative to the head 74 is internally threaded as at 78 to receive the externally threaded end 80 of an elongated substantially hollow conduit 82, the other end of the conduit being sealed and journaled for rotation in one end of a conventional elbow connector 84 having its other end connected through the conduit 80 (see FIG. 1) to a supply (not shown) of the liquid coolant 22. The coolant 22 preferably constitutes an admixture of oil and water.

The construction and arrangement of the elements described immediately above is such that the coolant 22 enters that end of the shaft 72 remote from the head 74 and discharges from the bore 76 at that end thereof that opens in the end 88 of the head 74 contained in the plane of its frustum.

At the opposite side of the reservoir and adjacent the sidewall 26 is located an electric motor 90 having a motor mounting base block 92 secured to the base plate 18 by conventional means. Disposed between the motor 90 and the adjacent sidewall 26 is a substantially hollow gear box 94 which includes a normally horizontal bottom wall 96 from a pair of opposed ends of which arise a pair of upright substantially parallel standards 98, 100, longitudinally spaced from one another. The standard 98 confronting the end wall 48 is formed with an inwardly extending cylindrical socket 102 which opens towards and is coaxially aligned with a bore 104 that extends transversely through the standard 100.

The opposed ends of a cylindrical shaft 106 are journaled for rotation in the socket 102 and bore 104, and fixedly connected thereto intermediate its ends is a first spur gear 108. That end of the shaft 106 which is journaled for rotation in the bore 104 extends beyond the remote sides of the standard and by conventional coupler means 110 it is connected to the drive shaft 112 of the motor 90.

A support structure is identified by the general reference numeral 114 and is seen to include a pair of upright laterally spaced and substantially parallel sidewalls 116, 118 (See FIGS. 1 and 2) fixedly secured at their lower ends to the base plate 18 and which has upper ends extending above the upper end of the reservoir 20.

The sidewalls 116, 118 are integrally joined to the diametrically opposed marginal edges of a pair of annular bosses 120, 122, disposed in space confronting and substantially parallel relationship relative to one another. Each of the transversely extending openings through the bosses 120, 122 is provided with a bushing 124, 126, respectively, in which the opposed ends of an elongated shaft 128 are journaled for rotation. One end of the shaft 128 is formed with an enlarged second frustoconical centering and support head 130 coaxially aligned with the first centering and support head 74, and the end 132 of the head 130 is disposed in the plane of its frustum and is positioned in confronting spaced and parallel relationship relative to the end 88.

The shaft 128 is formed with an axially extending cylindrical bore 134 in which is threaded an elongated substantially hollow cylindrical liner 136 extending coaxially therewith, and fixedly secured on the shaft 128 intermediate its opposed ends is a second spur gear 138 in mesh with the first spur gear 108 and which is driven by the latter. For safety in the operation of the apparatus 10, the spur gear 138 may be enclosed in a suitable casing 140, as shown in FIG. 2, which engages over and is supported by the bosses 120, 122.

Reference numeral 142 designates, in general, a sheet or strip metal casting drum or mold constructed according to this invention. The drum 142 is formed of steel or other suitable materials and is internally lubricated in a manner to be more fully described below.

The drum 142 comprises a pair of opposed substantially cylindrical sidewalls 144, 146, which support a double walled or jacketed involute mandrel 148 therebetween. In construct ing the mandrel 148, and referring specifically to FIG. 3 of the drawings, an elongated substantially cylindrical rod 150 is disposed perpendicular to the adjacent confronting sides of the sidewalls 144, 146 and has its opposed ends rigidly secured thereby by conventional means. The longitudinal axis of the rod 150 is radially offset from the centerpoints of the cylindrical sidewalls 144, 146, and as in the above referred to FIG., the rod 150 serves as the inner end closure means for a continuous liquid coolant passage 152 having its sides bounded by the laterally spaced and substantially parallel convoluted plates 154, 156, having their respective inner pair of ends rigidly connected to the rod 150 axially thereof and their respective sides closed by the adjacent confronting sides of the sidewalls 144, 146, to which they are rigidly connected or with which they are integrally formed. The opposite or outer end of the passage 152 is closed by fairing in the outer terminal end portion 156A (see FIG. 3) and welding the same as at 158 to adjacent portions of the underlying plate 154 at spaced intervals along its outer edge to provide a plurality of axially spaced elongated substantially rectangular liquid coolant outlet ports 160 (see FIGS. 2 and 3).

The liquid coolant inlet port 162 (see FIGS. 2 and 3) extends transversely through the sidewall 144 and opens into the passage 152 adjacent the rod 150. Second liquid coolant outlet port means 164 is provided and comprises an elongated slot which extends transversely through each of the sidewalls 144, 146 and which open into the passage 152 adjacent the faired in end 156A. The arrangement and the disposition of the liquid coolant outlet ports is such that the liquid coolant discharged through the outlet ports 160 is directed axially of the mandrel 148 whereas the liquid coolant discharged from the ports 164 will move across the exterior sides of the sidewalls 144, 146, to be collected in the reservoir 20.

The remotely disposed sides of the sidewalls 144, 146 are provided, respectively, with outwardly projecting coaxially aligned substantially hollow frustoconical sleeves 166, 168 having internal surfaces complementing the exterior sides of the heads 74, 130 on which they are releasably received and supported. It should be noted, however, that the fit between the head 74 and the sidewall 144 is such as to leave a space between the end 88 and the adjacent surface of the sidewall 144 to provide a closed chamber 169 which is in open communication with the outer end of the inlet port 162. Also to be observed is the flush fit between the exterior side of the sidewall 146 and the adjacent ends of the head 130 and its liner 136.

The friction fit between the shaft 128, casting drum 142, shaft 72 and the component elements thereof as described above enables this assembly to rotate as a unit upon energization of the motor 90 which effects the turning movement of the spur gear 108, that, in turn, causes the meshed spur gear 138 to rotate and thus drive the unit.

The cylindrical sidewall 144, on that side thereof remote from the sleeve 166, is formed with an inwardly extending coaxial cylindrical socket 170 which confronts an enlarged coaxial cylindrical opening 172 that extends transversely through the sidewall 146.

At 174 is designed a tundish, suitably lubricated and supported, the tundish 174 having an open upper end and being defined by the connected upright and opposed sidewalls 176, 178, inner end outer end walls 180, 182, respectively, and a bottom wall 183. The inner end wall 180 is formed with a laterally projecting cylindrical boss 184 which at its outer end terminates in a neck extension 186 of reduced diameter. The neck extension 186 is adapted for telescopic insertion and close fitting within the outer end of the liner 136 to effect a liquid tight connection therewith. The outer terminal end of the neck extension 186 communicates with the lower end of the tundish 174 via a hollow cylindrical passage 188 located coaxially with respect to the boss 184. As is seen in FIG. 1, the outer end wall 182 is inclined inwardly from its upper end and downwardly towards the inner wall 180 and includes a substantially vertical lower end section 190 which is traversed by a cylindrical opening 192 coaxially disposed with respect to the hollow cylindrical passage 188.

Reference numeral 194 designates an elongated helicoidal conveyor which includes an elongated substantially cylindrical shaft or main body portion 196 of uniform transverse cross section. One end of the main body portion 196 is integrally connected to the frustum end of an enlarged frustoconical terminal end portion 196A having a planer base 198 from which projects, in coaxial alignment therewith, a cylindrical stub axle 200, Fixedly secured or formed integral with the main body portion 196 and its extension 196A is a continuous helicoidal conveyor flight 202. The convolutions of the flight 202 are arranged relative to one another so as to provide a long lead therebetween. As is seen in FIG. 2, the lead between adjacent convolutions 202A of the flight 200 as they extend from the main body portion 196 is substantially uniform whereas the lead therebetween as indicated by reference numeral 2028 increases over the frustoconical terminal end portion 196A from substantially the place of its frustum to the plane of its base 198.

Again referring to FIG. 2, the helicoidal conveyor 194 is seen to be mounted in the apparatus or machine with substantially the whole of the frustoconical terminal end portion 196A and its flight 202B being disposed in an elongated hollow substantially cylindrical axially extending molten metal receiving chamber 203 which is formed by the first full inner convolution (see FIG. 3) of the plates 1 54, 156. As is apparent from FIG. 3, the adjacent pairs of convolutions of the plates 154, 156 are disposed in'spaced relationship relative to one another to define a convoluted continuous metal passageway 204 therebetween having a molten metal inlet opening 206 substantially at the completion of the first convolution of the plates 154, 156, the opening 206 establishing communication between the chamber 203 and the passageway 204 and a strip metal discharge opening 208 underlying the outer end portion 156A.

As is seen in FIG. 2, the stub axle 200 is journaled for rotation in the socket and the main body portion 196 of the conveyor 194 is coaxially received, together with its flight 202A, in the liner 136 and passage 188 of the boss 184 with the outer end thereof extending across the lower end of the tundish 174 in proximity to the bottom wall 184. The outer terminal end of the main body portion 196 is smoothly finished as at 210 and is journaled for rotation in an opening 212 extending transversely through the end wall section 190. As is seen in FIG. 1, the terminal end 210 extends on each side of the wall section and the exterior end thereof has a spur gear 214 fixedly secured thereon to serve a function to be described.

The machine or apparatus 10 also includes, as a component thereof, elevator apparatus designated by reference numeral 216 (see (FIGS. 1, 2 and 3). The elevator apparatus 216 is of conventional design and comprises an upright hollow cylindrical casing 218 disposed within the reservoir 20, and through the upper end 220 of the latter vertically reciprocates a cylindrical ram 222. The ram 222 is spring biased for upward movement away from the casing 218 and at its upper end the ram 222 is fixedly secured to the midportion of an elongated normally horizontal flat rectangular bed 224. The bed 224 is flanged as at 226, 228, along each of its longitudinally extending marginal edges to provide support means for the opposed ends of a pair of longitudinally spaced shafts 230, 232 having parallel axes disposed in a common horizontal plane. The shafts 230, 232 support axially elongated rollers 234, 236, respectively, and around the rollers 234, 236 is trained an endless flexible belt 238 formed of a suitable heat resistant material. As is seen in FIG. 1, the belt 238 has a width substantially equal to the width of the involute mandrel I48, and the perpendicular distance between the ends of the shafts 230, 232 is greater than the diameter of either of the sidewalls 144, 146 which, preferably, have equal diameters. The upward travel of the ram is limited in such a manner so as to normally maintain the belt 238 submersed below the liquid level of the coolant 22 and in juxtaposed position-relative to the mandrel 148,

A plurality of liquid coolant discharge nozzles 240 (only one being shown) are connected at axially spaced intervals on an elongated substantially rigid hollow conduit 242 and are in open communication therewith. The conduit 242 extends transversely of the mandrel 148 adjacent the upper end thereof and with the orifices of the nozzles facing in the direction contra to the direction of the rotation of the mandrel 148. The assembly comprising the conduit 242 and its associated nozzles 240 is supported on an inverted substantially U-shaped bracket device 244 which includes an elongated substantially rectangular bight member 246 having depending flanges 248 (only one being shown) at its opposed ends (see FIG. 3) which support the conduit 242 therebetween at one adjacent pair of ends thereof. The bight member 246 is provided with a beveled end section or peeler blade 250 that projects from a longitudinally extending marginal edge thereof in overhanging relation relative to the nozzles 240 and projects therebeyond to overhang a portion ofthe outermost one of the convolutions of the mandrel 148. The other adjacent pair of ends of the flanges 248 are fixedly connected on a shaft 250 which is suitably journaled for rotation in conventional support means (not shown) whereby the peeler blade 250 may be pivoted and secured in adjusted position relative to the mandrel 148. This is a conventional mechanical construction and, since it is not, per se, a constituent part of this invention, it is not, therefore, illustrated in the drawings. The length of the peeler blade 250 corresponds, relatively speaking, to the axial length of the mandrel 148 and, as is seen in FIG. 3, the peeler blade 250 is adjustable to a position enabling it to separate the leading edge of the outermost convolution of cast strip from its next adjacent convolution for passage over the bight portion 246 to pinch rolls 252 of conventional and well known construction.

The apparatus comprising the mandrel 148 and the sidewalls 144, 146, may be formed of separable components, if desired, or may be made integrally with one another in the manner shown herein to serve purposes to be described below.

PROCESS 1n the practice of the process of continuously coil casting strip or sheet metal according to this invention, let it be assumed that the apparatus has been constructed and is assembled in the manner described above and as illustrated in the drawings. The motor 90 is energized to effect rotation of the drum 142 in the direction the arrow A-l shown in FIG. 3, and motor means (not shown) is connected in driving relation with the spur gear 214 to drive the helicoidal conveyor 194 in the direction of the arrow A-2 (FIG. 3) and in a direction contra to the direction of the rotation of the drum 142. The tundish 174 is preheated in accordance with conventional practice and is lubricated in the usual manner as is the helicoidal conveyor 194, the sleeve 136, the chamber 203and the metal passageway 204.

A conventional liquid coolant recirculation system (not shown) is provided which maintains the liquid level of the coolant 22 in the reservoir at the desired level while at the same time the system supplies a sufficient quantity of the coolant (admixed oil and water) under pressure to the conduit 86 which it leaves through'the connector 84 and conduit 82 to follow the bore 76 for discharge into the chamber 169. The liquid coolant 22 is then forced through the inlet port 162 and travels the continuous passage 152 through the several convolutions of the mandrel 148, this liquid flow being in the direction of the arrows A-3, and the liquid is ultimately partially discharged through the outlet ports 16 opening into the outer sides of the sidewalls 144, 146, and flows thereover to be collected in the reservoir 20. Still other portions of the liquid coolant are discharged under pressure through the outlet ports 160 (see FIGS. 2 and 3) in a direction away from the trailing end of the involute mandrel 148.

With the machine 10 operating in the manner described supra, the crucible 154 filled with a molten metal is pivoted about its diametrically opposed axles 255 in the manner shown in FIG. 1 to effect the discharge of the molten metal 256 (steel in this instance) into the preheated tundish 174. The rate of the pour of the molten metal 256 into the tundish 174 is such as to maintain a sufficient head of molten metal therein as to stand well beyond and above the helicoidal conveyor 194. This head is preferably maintained throughout the length of the molten metal pour.

As the molten metal 256 fills the bottom of the tundish 174, the flight 202A forces the molten metal through the liner 136 and into the chamber 203. The rate of feed of the molten material 256 into the chamber 203 and the force exerted thereon by the conveyor flight 202A is such that the chamber 203 is filled to its capacity throughout substantially the duration of the length of the pour. it is to be understood at this point that apparatus other than that shown and described herein, ram means or a simple molten'metal gravity feed, could be employed to maintain the chamber 203 in its filled condition and to exert the required force necessary to cause the molten metal to enter the inlet opening 206 in the practice of this invention.

In the illustrated embodiment of the invention, the pressure exerted by the flight portion 20213 on the molten metal within the chamber 203 is sufficient to force the molten metal 256 through the inlet opening 206 to the liquid cooled molten metal passageway 204. As the molten metal enters and travels the several convolutions of the passageway 204, it is subjected to the cooling action of the liquid coolant 22 as it travels its jacketed passage 152 whereby the molten metal is cooled to change the physical characteristics thereof from one of a liquid to that ofa solid.

The hot now solidified metal emerges from the mandrel 148 through the discharge opening 208 in a direction contra to the direction of the rotation of the drum 142, and is discharged from the mandrel in sheet or strip form as is indicated at 300, the sheet or strip being deposited on the outer surface of the outermost one of the convolutions of the mandrel 148 over which it slidably engages. it is of importance to note that the emergent strip or sheet 300 is immediately subjected to a second and further cooling and lubrication operation through the utility ofthe discharge taken from the openings 160.

The emerging portion of the sheet of strip 300, still being flexible and pliant, will tend to bend over the mandrel 148 to conform to its configuration and to loosely wrap therearound. If desired, suitable guide means (not shown) could be employed to guide the sheet or strip 300 in this portion of its path of travel about the mandrel 148. Such guide means is not, however, essential to the practice of this invention, since the leading edge of the extruded material 300 forming the strip or sheet cast in accordance with this invention, will tend to bend and to contract about the mandrel 148 as it cools, and in so doing, the leading edge of the strip 300 traces a path of travel downwardly about the outermost one of the convolutions of the mandrel 148 toward and to the flexible belt 238 at which time the leading end of the strip 300 becomes supported and is guided during the course of its further travel around the then lower end portion of the mandrel 148 and upwardly about the other side thereof.

Other suitable guide means could be employed in circumferentially spaced relationship relative to mandrel 148 should the same prove to be necessary, the spacing thereof being dependent on the relative position of the discharge opening 208 as the mandrel 148 rotates. Since the use of such drive means is optional, for this feature of the invention could be practiced by hand, the same is not shown nor described with particularity in this specification.

As the leading end of the strip 300 is extruded and makes its downward course of travel about the mandrel 148, the discharge opening 203 being soon to be in the position shown in FIG. 3 of the drawings, the same will enter the coolant 22 disposed in the reservoir 20, thereby cooling the leading end and succeeding portions thereof and lubricating all surfaces of the first and following extruded convolutions.

Note should be here taken of the fact that as the second convolution 300A of the strip or sheet metal is cast, and in he casting of each succeeding convolution thereof, the first of the convolutions will overlie the next succeeding convolution in a rather loose convoluted arrangement much in the form of an offset spiral resembling a loosely wound watch spring. The adjacent loosely wound convolutions move, of course, at different speeds and the applied lubricant taken together with the progressively increasing diameters of the convolutions prevents the binding, welding or adhesion of adjacent surfaces thereof.

As succeeding convolutions of the cast metal are built up on the mandrel 148, the weight thereof is partially supported by the elevator means 216 which includes the platform 224 and the flexible belt 238, and, of course, the drum 142. Since a portion of the mandrel 148 is constantly immersed in the coolant 22 of the reservoir 20, continuous cooling and lubrication is offered thereto, the elevator means 216 descending in the reservoir 20 as the convolutions are built.

After a predetermined number of convolutions of the cast, strip or sheet metal 300 have accumulated on the mandrel 148, the bracket 244 is adjusted to position the peeler blade 250 in close proximity to the leading edge of the first convolution 300 whereby the same is peeled or stripped from the next underlying convolution to pass over the bight 246 for engagement with the pinch rollers 252 from whence it is advanced to a rolling mill, annealing, tempering or other types of processing lines, or optionally, may be wound into coils for further cooling and storage. The pinch rollers 252 pull the external wraps of the cast metal at a speed proportionately faster than the rotation of the mandrel 148 rotating at the same revolutions per minute, it being understood that the hot pliable metallic strip is retained on the mandrel 148 until it has solidified to the extent that it is capable of movement singularly and in a linear direction across the bight 246.

As is seen in FIG. 3 of the drawings, the underside of the leading end of the first convolution 300 of the sheet of strip material, as it approaches the peeler blade 250, is subjected to further cooling through the discharge of the liquid coolant through the nozzles 240, the spray therefrom also being so directed as to impinge on the outer side of the next succeeding convolution as it travels in its downward path for its final immersion in the liquid coolant 22 disposed in the reservoir 20.

After the pour has been completed and the entire length of the strip or sheet of metal has been cast, the casting drum 142 is preferably removed from between the two heads 74, 130 and is discarded. The removal was accomplished by first connecting appropriate hoisting apparatus to the drum 142 after which the hydraulic cylinder 30 is actuated in such a manner as to cause piston rod 36 to retract to the left (as viewed in PK]. 1), effecting the separation of the head 74 from the sleeve 166. The drum 142 may then be moved laterally, to the left as viewed in FIG. 2, to effect the separation of the sleeve 168 from the head 130 whereby the drum 142 is completely disconnected from the remainder of the described apparatus. A new drum may be quickly and easily installed between the heads 74, 130 through a reversal of the above steps of procedure.

It is to be understood that this invention contemplates the casting of metal strips or sheets wherein the width thereof may be made to vary in accordance with the axial length of the casting passage 204 of the mandrel 148. The same result could be achieved through the simple expedient of increasing and/or decreasing the axial length of the drums 142 per se.

Whatever may be the construction of the drums 142, the fact that the same are inexpensive to manufacture, makes the same economically expendable and, as has been stated above, may be discarded at the end of each pour or in the event of some mishap which inadvertently causes the metal being cast to stick therein while tracing its casting passage 204 as it traverses the mandrel 148.

Through actual testing it has been found that if the casting drum 142 is intermittently reversed, the problem of the metal sticking during the casting operation is largely eliminated.

As the specification above connects, one of the main features of this inventionis the casting of molten material in the involute drum 142. Here it cools to set" or solidify into a coil form, a strip or sheet, and the set is accomplished while the coil form, strip or sheet and the drum 142 move relative to one another to achieve the continuous metal casting.

And finally, while the invention disclosed herein is primarily addressed to ferrous materials such as steel, the same process and apparatus finds utility in the casting of nonferrous metals.

Having described and illustrated in considerable detail one embodiment of this invention, it will be understood that the same is herein offered only by way of example, and that this invention is to be limited only by the scope of the appended claims.

lclaim:

l. A method for casting a molten metal as a continuous strip comprising the steps of forcing a flow of said molten metal through a centrally located inlet port of a continuous involute passage having a normally horizontal central axis and being formed of a plurality of concentric spiral communicating convolutions spaced from one another, and circulating a coolant medium around each convolution in heat exchange relationship with said metal to effect a change of state of said metal from one of a liquid to that of a substantially solid strip and casting said metal in concentric spiral convolutions in said passage, and discharging said strip from said passage.

2. A method for casting a molten metal as defined in claim 1, and the further step of rotating said passage in a direction contra to the forced direction of flow of said metal in said involute passage.

3. A method for casting a molten metal as defined in claim 1, and the further steps of circulating said coolant material over the sides of said passage while rotating said passage in a direction contra to the flow of said metal therethrough, receiving the discharged strip from said passage in convoluted form,

and immersing the convolutions in a liquid coolant.

4. A method for casting a molten metal as defined ll'l claim 1, and the further steps of circulating said coolant material over the sides of said passage and rotating said passage in a direction contra to the metal flow therethrough, receiving the discharged strip of metal from said passage in convoluted form, immersing the convolutions in a liquid coolant, and the further step of peeling the leading end of the first convolution of said strip from the next succeeding one thereof.

5. A method for casting a molten metal as defined in claim 1, and the further steps of circulating said coolant material over the sides of said passage and rotating said passage in a direction contra to the metal flow therethrough, receiving the discharged strip from said passage in convoluted form, immersing the convolutions from the next succeeding one thereof, and spraying said leading end of said strip with a liquid coolant at substantially the point of peeling.

6. A method for casting a molten metal as defined in claim 1, wherein said heat exchange relation is effective substantially continuously throughout the entire length of the involute passage.

7. A method for casting a molten metal as defined in claim 1, wherein said heat exchange elation is effective substantially continuously throughout the length of the involute passage, and the further step of immersing the leading end of the cast strip in a second cooling medium.

8. A method for casting a molten metal as defined in claim I, wherein said heat exchange relation is effective substantially continuously throughout the length of the involute passage, immersing the leading end of the cast strip in a liquid coolant bath, and guiding said leading end to a terminal station while spraying said leading end with a liquid coolant.

9. A method for casting a molten metal as defined in claim 8, and the further step of rotating said passage in a direction contra to the direction of forced movement of said molten metal and strip therein.

10. A method for casting a molten metal as defined in claim 9, and the further step of intermittently reversing the direction of rotation of said passage as said material is cast therein.

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