US3279000A

US3279000A - Apparatus for continuous casting of metal

Info

Publication number: US3279000A
Application number: US334197A
Authority: US
Inventors: Daniel B Cofer; Dale D Proctor; George C Ward
Original assignee: Southwire Co LLC
Current assignee: Southwire Co LLC
Priority date: 1963-12-30
Filing date: 1963-12-30
Publication date: 1966-10-18
Anticipated expiration: 1983-10-18
Also published as: GB1034410A; DE1458198B1; BE657702A; CH459476A; ES369463A3; FR1420797A

Description

D. B. COFER ET AL APPARATUS FOR CONTINUOUS CASTING 0F METAL Filed Dec. 50, 1963 Oct. 18, 1966 4 Sheets-Sheet 1 C Y m I PQ AT TORNE Y8 Oct. 18, 1966 c R ET AL 3,279,000

APPARATUS FOR CONTINUOUS CASTING 0F METAL 4 Sheets-Sheet 2 Filed Dec. 30, 1963 INVENTORSI Dame! 5. COM

Dale D. Proctor BY George C. Ward ATTORNEYS Oct. 18, 1966 Filed Dec. 30. 1963 D. B. COFER L APPARATUS FOR CONTINUOUS CASTING 0F METAL 4 Sheets-Sheet 3 INVENTORS: Daniel B. Cofer Dale D. rector P BY G or e C. rd M 1% RNEYS V Oct. 18, 1966 FER ET AL 3,279,000

APPARATUS FOR CONTINUOUS CASTING OF METAL Fiied Dec. 30. 19s: 7 4 Sheets-Sheet 4 H IHI l n nu INVENTORS: Damel B. Cofer BY Dale D. Procio George C. W

Q Jw a Mg ATTORNEYS United States Patent 3,279,000 APPARATUS FOR CONTINUOUS CASTING 0F METAL Daniel B. Cofer, Dale D. Proctor, and George C. Ward,

Carrollton, Ga., assignors to Southwire Company, Carrollton, Ga., a corporation of Georgia Filed Dec. 30, 1963, Ser. No. 334,197 22 Claims. (Cl. 2257.4)

This invention relates to apparatus for continuous casting of metal and is more particularly concerned with a continuous casting machine in which different metals may be cast and which is particularly suited for the casting of copper into a continuous rod suitable for subsequently being rolled in a rolling mill, then drawn into wire.

In the past, continuous casting wheels or drums have been employed for casting aluminum bars which have subsequently been drawn into aluminum wire. Indeed, many patents have been issued to Ilario Properzi and others relating to such casting wheels and equipment employed inconjection therewith. US. Patent No. 2,865,- 067 illustrates generally the type of prior art casting wheel to which we refer.

These prior art casting Wheels have included a rotatable drum having a grooved periphery, around a portion of which a steel endless belt passes, the belt being of greater length than the circumference of the drum and diverging therefrom on opposite sides. Hence, there is formed an inlet into which molten metal is poured and an exit from which the solidified rod (or bar) is withdrawn. The core or central portion of the drum is hollow to permit the circulation of a coolant, such as water.

When such prior art devices are employed for casting copper, the copper is cooled slowly and as a rule is discharged in an unevenly cooled condition. That is to say that, periodically along the length of the discharged copper, there are dark spots and light spots which apparently alfect the internal structure of the copper rod to an extent that in the subsequent rolling operation, the copper rod is not sufiiciently ductile to permit its reduction to small diameter wire.

We believe that the uneven cooling of the prior art casting drum is due to the fact that the water coolant is relatively in a quiescent condition adjacent the inside surface of the casting wheel and the sudden heating of this water adjacent the inside surface as the molten metal passes thereby causes a portion of the water to flash boil, the vapors being carried around with the wheel for a short distance and then being collapsed. The flash boiling removes the water from an increment of the casting wheel and the subsequent condensation of the steam permitting the water again to contact the increment as another increment. This sets up a pulsating situation for the water which causes uneven cooling of the increments and also causes the cooling to be slowed to an extent that the prior art casting wheel is impractical for casting copper rods. Thus, it has generally been believed that the continuous casting of copper for subsequent drawing to wire size is impossible or impractical.

The prior art literature has suggested that the conductivity of a copper rod is the function of the initial density of the bar or rod from which the wire is rolled or drawn, the conductivity being directly proportional to the density of the cast bar or rod. Hence, it would appear to be desirable in order to produce a copper wire having as high conductivity as possible to control the conditions under Patented Oct. 18, 1966 "ice which the bar or rod is cast so as to produce as dense a casting as possible. Furthermore, a more dense bar or rod would require less mechanical Working in order to produce the more dense wire therefrom.

In the past, cooper has been cast in situ inblock or bar form in a mold which is left in ambient air to cool. Under such conditions the copper tends to cool from the sides and bottom slowly, thereby creating the dendritic crystalline structure on three sides; however, the upper portion of the copper appeared to have a spongy structure which is honeycombed with small voids or gas spaces. The density of this copper bar is approximately 8.47-8.59. If such a copper bar were cooled from all sides, the .concentration of the spongy structure or small voids in the structure would be toward the central of the bar. The voids or spongy structure interfere with the subsequent drawing of the copper and, in general, tend to make the bar less capable to being drawn into fine wire.

Briefly, the apparatus of the present invention which tends to obviate the problems described above includes a disc-shaped inner flange which is supported concentrically at the end of a rotatable shaft and extends radially therefrom in all directions. A ring shaped or annular casting wheel or member is removably clamped to the front face of the inner flange by a spring loaded outer flange, the spring loading of which permits the casting member to expand and contract with thermal changes. The casting member is provided with a casting groove in its outer periphery while the inner periphery and sides thereof have cooling fins which provide for the rapid dissipation of the heat from the casting member. To facilitate this rapid and even cooling of the molten metal and reduce to a minimum the tendency of the coolant to flash boil, circumferentially spaced jet nozzles are disposed along the inner and outer peripheries of the casting member, the outer jet nozzles directing the coolant again-st an endless belt, of greater length than the circumference of the casting member, as it partially circumscribes the casting member for closing the open portion of the casting cavity or groove. The inner nozzles direct the coolant against the inner periphery of the casting member and the side nozzles direct the coolant against the sides of the casting member. By such an arrangement the copper or other molten metal, which is continuously poured into the inlet formed by the belt and casting member as they meet, is cooled so rapidly that the gases which would normally create the voids are not given sufiicient time to form. Thus, an even dense bar of copper emerges from the exit, the copper having a density suflicient for being drawn into fine wire.

Accordingly, it is an object of the present invention to provide a continuous casting machine which is particularly suited for casting copper rod having characteristics which permit the subsequent drawing of the rod into fine wires.

Another object of the present invention is to provide a continuous casting machine in which the cooling of all sides of the cast metal may be selectively controlled,

Another object of the present invention is to provide a continuous casting machine in which the element defining the casting cavity may be readily and easily replaced and is so retained that thermal changes do not set up stresses in the machine.

Another object of the present invention is to provide a continuous casting machine which is capable of quickly and evenly cooling molten metal immediately after it is received in the casting machine.

Another object of the present invention is to provide, in a continuous casting machine, an efiicient means by which the incremental cooling of the motlen metal may be controlled.

Another object of the present invention is to provide a continuous casting machine which is capable of casting a continuous metal rod from molten metal directed into the casting machine, the metal rod having a dense, relatively uniform crystalline structure and being of a cross sectional configuration more suitable for subsequent reduction in cross section.

Another object of the present invention is to provide, in a continuous casting machine, a cooling system which will quickly and efliciently cool the molten metal and casting ring of the casting machine without appreciable flash boiling of the coolant.

Another object of the present invention is to provide a continuous casting machine which is inexpensive to manufacture, durable in structure and eflicient in operation.

Other objects, features andadv-antages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings wherein like characters of reference designate corresponding parts and in which:

FIG. 1 is a front elevational view of a continuous casting machine constructed in accordance with the present invention, parts thereof being broken away.

FIG. 2 is an enlarged side elevational view, partially in cross-section, of one of the jet nozzles employed in the continuous casting machine illustrated in FIG. 1.

FIG. 3 is a cross-sectional view taken substantially along line 3-3 in FIG. 1.

FIG, 4 is a vertical cross-sectional view of the continuous casting machine shown in FIG. 1.

FIG. 5 is a cross-sectional view of the peripheral portion of the casting machine illustrated in FIG. 1 and showing a modified form casting cavity having trapezoidal cross-section.

FIG. 6 is a diagrammatical representation of the automatic control for the cooling system of the present invention.

Referring now in detail to the embodiment chosen for the purpose of illustrating the present invention, it being understood that in its broader aspects the present invention is not limited to the exact details herein depicted, numeral 10 denotes a central horizontally extending shaft which is appropriately journalled by a base 11 for rotation about its axis, the shaft being driven by a prime mover, such as a motor (not shown). The shaft 10 defines the central transverse axis of the machine illustrated. Forwardly of the base 11, the end of shaft 10 is provided with a flat, disc shaped, radially extending, face plate 12.

The central portions of shaft 10 and face plate 12 are provided with an internally threaded axial bore 13 which threadedly receives one end of a cylindrical stub shaft 14, the other end of which protrudes along the transverse axis of the machine beyond face plate 12 and is externally threaded to receive the nut 15. Nut 15 and washer 16 retain a bearing sleeve 17 on the shaft 14 and urge it against the central portion of face plate 12 for rotation therewith.

Surrounding the rear portion of sleeve 17 and secured by bolts 18 to the front or forward surface of face plate 12 is an innerflange 19 which is a disc shaped member having a circular periphery 20. The inner flange 19 is appreciably larger in diameter than the face plate 12 and its front surface, adjacent periphery 20, is provided with an annular groove 21. As best seen in FIG, 3, the groove 21 is defined by concentric inner and outer walls, the inner wall being deeper than the outer wall so that the base position of groove 21 tapers outwardly and forwardly between the concentric walls. Since the groove 21 is spaced inwardly of the periphery 20, the periphery and groove 4 21 define, therebetween, a forwardly extending shoulder 22.

For forming an envelope to receive the molten metal, the inner flange 19 carries a casting member 30. The casting wheel or member 30 is formed from copper, and is a ring shaped member, having a transversely flat outer periphery within the central portion of which is an annular peripheral casting groove 31 for receiving molten metal. In cross-section, casting groove 31 is defined by a pair of inwardly converging opposed

flat sides

32 and 33 which converge toward the radial axis of the machine'and subtend an angle of approximately 10 degrees therebetween. The casting cavity 31 has either an arcuate, con-, cave bottom 34, as seen in FIG. 3, or a flat bottom 134, as seen in FIG. 5. The flat bottom 134 has curved extremiti es which merge with the inner end portions of

sides

32 and 33, while the rounded, concave bottom 34 is substantially hemisphericalto provide end portions which themselves merge tangentially (or essentially tangentially) with the inner ends of

sides

32 and 33.

The forward and rear sides of the casting member 30 are provided with a plurality of diminishing diameter concentric grooves which define therebetween a plurality of spaced, axially extending,

annular side fins

35 and 36 from the periphery of the member 30 inwardly to the, region of the central portion of member 30. The central portion of the inner periphery of casting member 30, in like manner, is provided with inner fins 37 which are spaced axially from each other and are disposed radially parallel to each other.

- Adjacent the inner periphery and protruding in opposite directions, i.e., forwardly and rearwardly from .the sides of casting member 30, are a pair of peripheral shoulders 38 and 39, the inner sides of which are extensions of the inner periphery of casting member 30 and the outer sides of which are concentric with, but of larger diameter than, the inner sides. The faces of the shoulders taper outwardly so that the taper of the face of rear shoulders 39 conforms to the taper of the base portion of groove i an annular outer flange 40 which is carried by the inner flange 19 andryieldably urged against the outer side of casting member 30. In more detail, the outer flange 401 is a flat, annular member of substantially the same thick:

ness and outer diameter as the inner flange 19. The rear surface of flange 40 is provided with an annular groove 41 which is opposite to and complementary with groove i 21 of inner flange 19 and receives shoulder 38 of the casting member 30. The flange 40 thence extends inwardly beyond the casting member 30 sufficiently to receive therethrough a plurality of circumferentially spaced, parallel stove bolts 42 which protrude through the inner flange 19, inwardly of the casting member 30. The bolts.

42 are sufficiently long that they protrude forwardly, i.e., axially, beyond flange 40 and are each provided with a helical spring 43. One end of spring 43 is received in a counterbored recess in flange 40 surrounding bolt 42,; and the other end engages a washer 44 and urges it against a nut 45 on the end of bolt 42. Hence, at all times, the casting member 30 is yieldably clamped between inner flange 19'and outer flange 40 and is permitted limited expansion and contraction since the springs, such as spring 43, will permit the outer flange 40 to move forwardly and rearwardly while being urged rearwardly toward flange 19 into its clamping position.

The inner periphery of outer flange 40 is grooved appropriately for, and receives one side of, and annular inner shield 46 which protrudes forwardly to terminate in about the same plane with the forward ends of bolts 42.

The front surface, outwardly of bolts 42, receives an outer annular shield 47, which is concentric with the inner shield 46. Between the inner shield 46 and outer shield 47, and spaced forwardly of flange 40 and outwardly of bolts 42, is an intermediate annular shield 48 which is carried by the periphery of a front plate 49 which extends over the interior of the machine, the front plate 49 being disposed slightly forwardly of the front edge of shield 46.

The drum described above is rotated in a clockwise direction as indicated by the arrow in FIG. 1. As best seen in FIG. 1, the usual end-less, flat, flexible, metal belt 50, of greater length than the circumference of the drum described above, passes around approximately 180 degrees of the drum and then passes around an idler drum (not shown). Since the idler drum for belt 50 and drive mechanism for shaft are shown in such patents as U.S. Patents Nos. 2,865,067; 2,659,948; 2,710,433 and 2,659,- 949, these features are not illustrated in the present application. The belt 50 is approximately the same width as the width of the casting member 30 and functions to close the outer side of the outwardly opening casting cavity 31, progressively moving to form a continuously formed, open ended, arcuate, tubular member or envelope having an inlet at approximately the 45 degree position of the casting member 30 and an exit at approximately the 225 degree position of the casting member 30.

As will be understood by those skilled in the art, molten metal from a pouring pot 51 is introduced by gravity, by way of a spout 52 into the casting cavity 31, at the inlet of the tubular member, as the belt 50 closes the outer side of the casting cavity 31. After being cooled and transported in an arcuate path, the cast metal is discharged as a continuous cast rod 53 from the exit end of the tubular member, as the belt 50 diverges from the casting member 30. During the period of travel along the lower portion of the casting member 30, the casting member and belt 50 are subjected from all sides to cooling as will be pointed out hereinbelow.

Cooling system According to the present invention, the cooling system for quickly solidifying the molten metal received in casting cavity 31, and for further cooling the empty casting member 30 includes a plurality of jet nozzles disposed on the three sides of the casting member 30 and on the fourth side defined by the belt 50. Each group of jet nozzles directs a high velocity stream of coolant, such as water, against the casting member 30 or belt 50 in such quantity that there is very little opportunity for the coolant, i.e. water, to be vaporized to any great extent, the jet nozzles being so distributed that the cast metal is cooled evenly to a prescribed surface temperature at the time of discharge, and the casting member 30 is further cooled to present a cool surface for receiving additional molten metal.

For supplying coolant to the inner periphery of the casting member 30, an inner cooling system is provided with three separately or selectively controlled, circumferentially disposed cooling stages having a common inner header or manifold, denoted generally by the numeral 55. The header 55 is a closed, hollow, annular member having a hub or collar 56 which circumscribes the bearin g sleeve 17, being spaced therefrom by anti-friction bearings 57 and 58. Front and rear, spaced, parallel,

circular plates

59 and 60 are secured .to 'the ends of collar 56 and extend radially therefrom. The peripheries of these

plates

59 and 60 are joined by a cylindrical cap 61.

Within the header 55 are three radially extending

divider plates

62, 63 and 64, seen in FIG. 4. Plate 62 is disposed upright While plate 63 is disposed approximately 150 degrees therefrom, and plate 64 is disposed at approximately 2'20 degrees from palte 62. Thus, three separate compartments are provided in the inner header 55.

Spoke-like

hollow pipes

65, 66 and 67 radiate from the cap 61 and are received by an annular base member 68 of the hollow outer header 70. Pipes 65 communicate with the first compartment of the header 55, the pipes 66 communicate with the second compartment of header 55 and the pipes 67 communicate with the third compartment of header 55. The outer heater 70 includes an outer annular cap or spray ring 71 concentric with the base member 68 and a pair of side walls 72 and 73 which connect the sides of the base member 68 and the annular cap 71. The outer header 70 is provided with three

baflie plates

74, 75 and 76 which separate the outer header 70 into three separate compartments, the plate 74 being disposed upright and the

plate

75 and 76 being disposed 135 degrees and 270 degrees therefrom.

The outer cap 71 is provided with spaced holes disposed approximately 10 degrees from each other, the holes being internally threaded to receive, respectivly, the jet nozzles 77 which are angled in a clockwise direction at approximately 45 degrees from the radius. As illustrated in FIG. 2, each jet nozzle 77 includes a 45 degree elbow 78 to which is mounted a flat spray nozzle 78a having a body with a jet orifice 79 and a deflector 80, such as that disclosed in U.S. Patent No. 2,530,671. Each nozzle 77 is arranged to direct the coolant angularly outward to impinge upon the inner periphery of the casting member 30 at a position 17 degrees advanced in a clockwise direction from the outlet of the nozzle 77.

It will be understood that the inner and

outer headers

55 and 70 are disposed concentrically with respect to casting member 30 and the

headers

55 and 70 are within the confines of the drum, as defined by the inner flange 19 and the front plate 49. Three

coolant supply pipes

81, 82 and 83 supply coolant, such as water, respectively, to the compartments of the inner header 55.

The pipes '81, 82 and 83 are respectively provided with control means, such as

valves

84, 85 and 86, by which the amount of coolant flowing to a particular compartment may be varied as desired. Pipes 81, 82.and 83 are so arranged that they pass through the front plate 49 and provide support therefor.

Pipes

81, 82 and 83 terminate at the front plate 59 of header 55 and are in communication, respectively, with appropriate holes leading to the three compartments of the header 55. Hence the

headers

55 and 70 do not rotate but remain fixed as the drum, including casting member 30, rotates thereabout.

It will be understood that the pipe 81 communicates with the compartment defined by

divider plates

62 and 63, the pipe 82 communicates with the compartment defined by divider plates 63 and 64 and the pipe 83 is in communication with the compartment defined by divider plates 64 and 65.

The spokes or

hollow tubes

65, 66 and 67 provide communication between respective compartments of the inner and

outer headers

55 and 70; therefore, the coolant from pipe 81, after entering the compartment of the inner header 55 passes outwardly therefrom through the three spoke-like tubes 65 into the first stage compartment of the outer header 70, as defined by

divider plates

74 and 75 Thence, the coolant is sprayed by the group of jet nozzles 77 which are disposed from 0 degrees to 135 degrees of the arc of the outer header 70 and constitute the first stage cooling means.

The coolant from pipe 81 is directed by the nozzles 77 against the bottom of successive increments of rotating casting member 30 as the increments approach the zone to receive the molten metal from spout 52, and as the increments travel approximately degrees immediately after receiving the molten metal.

Since much of the heat of the molten metal must be dissipated during the first quarter revolution of the casting member 30 after receiving the molten metal, the pipe 81 is relatively large, hence the volume of water delivered to nozzles 77 of the first cooling stage is relatively large. The coolant impinges upon the area of fins 37 at acute angles to the path of travel and is deflected, or cascades,

downwardly, being collected at the bottom portion of the machine until it overflows around the

shields

46 and 47.

In the second cooling stage, the pipe 82 communicates with a compartment of the inner header 55 so as to feed coolant through two tubes 66 to the outer header 70, thence through the nozzles 77 which communicate with the compartment between

bafiies

75 and 76. As in the preceding stage of cooling, the water from thesesecond stage nozzles 77 is directed against the fins 37 for cooling the metal from the time it passes the first cooling stage until it emerges from the exit as solid rod 53 at a position of approximately 270 degrees as the drum is viewed in FIG. 1. At this point, if the metal is copper, the metal bar 53 should be red hot, or about 1800 degrees F.

It is desirable, between the time an increment of the casting member 30 releases the bar 53 and the time an increment is positioned for receiving the molten metal, to cool the casting member 30 further so that it is relatively cool when the molten metal is received. Thus, a third stage of cooling is provided wherein the coolant from the remaining nozzles 77,i.e. the nozzles disposed from 270 degrees to 360 degrees with respect to the drum, direct the coolant against the fins 37. The pipe 83 communicates with the compartment between divider pates 64 and 62 for supplying this coolant through tubes 67 to the compartment between

divider plates

76 and 74, thence to the third stage nozzles 77.

The coolant from the two latter stages of cooling also collects in the bottom portion of the drum and drains therefrom in the same way the coolant from the first stage drains therefrom.

By varying the openings of

valves

84, 85 and 86 the temperature of increments of the casting member 30 can be varied to achieve controlled cooling of the molten metal, as well as controlled cooling of the casting member 30.

To supplement the internal cooling system described above, and to cool the metal more evenly from the time it is received until it is discharged as bar 53, side cooling systems are provided which simultaneously direct the coolant inwardly against opposite sides of the casting member 30. Also a belt cooling system directs coolant against the outer surface of the belt 50 as it passes around casting member 30.

The side cooling systems include a pair of

arcuate pipes

90 and 91 disposed on opposite sides of the casting member 30 from approximately 90 degrees to 250 degrees of the drum, these

pipes

90 and 91 conforming to the curvature of the casting member 30. All nozzles 92 and 93 (which are each identical to nozzle 77) are threadedly carried by the

pipes

90 and 91, respectively, and direct coolant in tangential planes inwardly from

pipes

90 and 91, the coolant being directed in a clockwise direction (as viewed in FIG. 1.) inwardly so as to impinge upon and between the

fins

35 and 36 at acute angles. The

pipes

90 and 91 are provided with valves 94 and 95 whereby the amount of coolant directed against each side of the casting member 30 may be controlled. Hence, the side cooling systems supply a predetermined amount of coolant to both sides of successive increments of the casting member 30 from the time immediately prior to the time the increments release the metal as rod '53.

The belt cooling system includes an arcuate pipe 96 having a valve 97, the pipe 96 being disposed concentrically outward of that portion of belt 50 which is disposed around casting member 30. Nozzles 98, (which are each identical to nozzle 77) project inwardly and in a clockwise direction, as viewed in FIG. 1, for directing coolant against the outer surface of increments of the belt 50 from the time the increments of the belt 50 (cooperating with the casting wheel 30) receive the molten metal until immediately prior to the time the increment of belt 50 releases the metal as rod 53. The last few nozzles, i.e. the last two nozzles 98a, are preferably directed in a counterclockwise direction inwardly so as to retard the spray of coolant along the line of travel of belt 50 as the 'belt 50 diverges from casting member 30. I

Above the position at which the belt 50 diverges from the casting member is the usual extractor shoe 99 supported by a bracket 100 in the path of travel which the rod 53 could take if it were retained in the casting cavity 31. The function of this shoe 99 is to deflect the bar 53 outwardly in the event the bar 53 adheres to the cavity 31.

The mechanism thus far described is disposed in a suitable well in a plant and is supported by the floor 101 of the well. are appropriately supported by brackets such as brackets 102 extending upwardly from floor 10 1 and by brackets, such as brackets 104, which project from wall 103 of the well.

Automatic control for cooling system As seen in FIG. 6, the flow of the coolant may, if desired be automatic and controlled in accordance with the temperature of the metal rod 53 as it emerges from the casting wheel. To accomplish this, a thermocouple type pyrometer 200 is mounted on a suitable support (not shown) adjacent the rod 53 for viewing the same as it emerges from the casting member 30. Electrical electrically connected to a variably positionable brush.

207 on the resistor 208 of a potentiometer 209. An additional resistor 210 is arranged in parallel with the resistor 208 and these

resistors

208 and 210 are arranged in parallel with a resistor 211 of a first leg of a Wheatstone bridge, denoted generallyby numeral 212.

The first leg of the Wheatstone bridge 212 also has a resistor 213 in series with the parallel

disposed resistors

208, 210 and 211.

The second, third and fourth legs of the Wheatstone bridge 212 are respectively provided with

resistors

214, 215 and 216, the

resistors

211, 213 and 214 constituting one side of the bridge 212 and the resistors 215 and 216 constituting the other side thereof.

A source of constant voltage, such as a standard electric cell 217 is connected across the junction of resistors 213 and 214 to the junction of resistors 215 and 216 while a wire'218 leads from the junction of

resistors

214 and 215 to the control mechanism 203.

It will be understood that, initially, the main control circuit, which includes the conduit 201, pyrometer 200 conduit 202, potentiometer 209, bridge 212 and wire 218, is designed to provide a zero potential when the pyrometer 200 reads a prescribed temperature, such as 1800" F. An increase or decrease in this prescribed temperature will increase or decrease the potential outi put of the pyrometer 200 and unbalance the main circuit to provide a current flow, in one direction if a higher temperature is read and a current flow in the opposite.

direction if a lower temperature is read.

The main control circuit, in turn, signals the control mechanism 203 to control the feed of current, via wires. 206 to motor 205 to control the actuation and deactuation of the motor 205, as well as the direction of rotation of the motor 205. In other words, if the current flows in one direction in the main control circuit, it will dictate that the control mechanism 203 direct current to the motor 205 for causing it to rotate in one direction and if current flows in an opposite direction, in the main circuit, the control mechanism 203 directs current to The

pipes

81, 82, 83, 90, 91 and 96 gen or free hydrogen may also be present. Since all these components produce gases, the voids are created because of the presence of these gases in the metal which is cooled from the outside. The presence of minor amounts of gases in the prior art processes of casting copper create what is known as tough pitch copper and is desirable in such prior art processes.

In the process of the present invention, however, the presence of such gases is undesirable and essentially eliminated, giving a dense copper rod 53 which requires less rolling in order to produce a copper wire having the usual density of from 8.87 to 8.94 without the necessity of working the copper sufficiently to eliminate or weld the voids.

The rod 53 which we have produced is relatively small with respect to the prior art, in situ cast bar, the bar 53, if trapezoidal, such as that produced from cavity 131, measuring, in cross-section, along its major base (the base adjacent belt 50) from approximately 1% inches to approximately 2 inches and preferably 1 inches. The converging sides of the bar 53, in cross-section, are likewise from approximately 1% inches to approximately 2 inches and preferably 1 ,4 inches while the minor base is from approximately inch to approximately 1% inches and preferably 1 inch exclusive of the curvature radii. If, on the other hand, the rod 53 has a crowned inner side, such as if the bar 53 were cast in cavity 3 1, the base thereof i.e., the portion adjacent belt 50 would measure from approximately 1% inches to approximately 2 inches and preferably 1.8 inches while the sides would measure from approximately 1 /3 inches to approximately /3 inch and preferably 1.25 inches, and the depth of the bar measures from 1 inch to 2 inches, being preferably 1.6 inches. The radius of curvature of the crown would then be from approximately inch to inch and preferably /2 inch.

Since the coolant is directed from four sides against the casting member 30 and against the belt 50, the molten metal within the casting cavity 31 is, likewise, cooled from all sides.

This creates from the molten metal poured into the mold or casting cavity 31 or 131, a solidified rod 53 having an acicular grain structure in which the crystals are progressively larger from all sides inwardly. These crystals are oriented generally perpendicular to the surfaces adjacent thereto. Hence, in a typical cross-section of the trapezoidal rod 53, the crystals which are adjacent the opposite sides of rod 53, are oriented in generally parallel planes, and protrude inwardly to a central trunk portion disposed perpendicular thereto. The crystals which are adjacent the major base and minor bases are disposed in planes perpendicular to the planes of the crystals adjacent the sides. With even cooling from all sides, diagonal branch lines which extend divergently from the ends of the central trunk, separate the side crystals from the base crystals. Thus, a tree-like appearance is produced wherein the trunk of the tree is generally centered between the sides of the cast metal and branches extend generally diagonally to the corners of the cast metal. This dendritic structure, we have found, is capable of being worked in the rolling mill, and drawn to create small diameter wire.

It will be remembered that the casting member 30 is preferably made from copper itself and because of the rapid cooling of the molten metal, and because of the precooling of the casting member 30, immediately before it receives the molten copper, there is little danger of the casting members being heated sufliciently at any time to weld to the copper rod 53 as it is formed. The spray within the interior of the drum, as pointed out above, is directed in clockwise direction and hence the coolant which collects in the bottom portion of the drum is urged in clockwise direction and overflows at a position beyond the 180 position so as to pass out of the drum by flowing over the flange 40, and over the

shields

46 and 47.

Because of the high volume of coolant introduced into the interior of the drum by the

pipes

81, 82 and 83, the level of the coolant within the drum may build up, thereby increasing the flow of the coolant from the drum. Any coolant which cascades between the

headers

55 and 70 and the back flange may readily pass through the open area between the

spokes

65, 66 and 67 and, therefore, there appears to be no concentration of the coolant within the drum in any uneven distribution.

The

fins

35, 36 and 37 permit a rapid cooling of the casting member 30, thereby drawing out the heat from the metal within the casting cavity 30 at a rate appropriate to provide the dendritic structure of the type which has the trunk portion of the structure centered toward the center of the rod 53. Furthermore, the casting member being of copper permits the rapid conduction of the heat away from the casting cavity 31.

If it is found that the structure of the cast rod or bar 53 is uneven, indicating more cooling on one side than another, the appropriate valve or valves, such as

valves

84 and 97, may be opened or closed partially to adjust for the desired amount of cooling along a particular side. Further, if the rod or bar 53 emerges from the casting member 30 at a temperature different from the desired temperature, the valve 86 may be manipulated to alter this temperature. Furthermore, if the portion of the casting member 30, which is to be cooled immediately prior to receiving the molten metal, is at a higher or lower temperature than desired, manipulation of the valve 86 will result in an adjustment of this temperature.

With the speed of the casting member properly adjusted, the volume of the coolant properly adjusted and the temperature and the flow of the molten metal properly adjusted, the machine will function with little attention.

When the mechanism is to be operated automatically, all

manual control valves

84, 85, 86, 94, and 97 are opened. This permits the valve 222 or the valve 223, to control the quantity of water fed to the casting wheel. The pyrometer 200, as explained above, controls motor 205 which, in turn, controls the amount of opening of the valve 222. Therefore, if the temperature of the surface of rod 53 is too high, the pyrometer 200 signals motor 205 to move valve 222 toward a more opened condition and, conversely, when the temperature of the surface of rod 53 is too low, the pyrometer 200 signals the motor 205 to move valve 222 toward a closed condition.

The bypass valve 223 serves two functions. First, it may be partially opened and operated in conjunction with valve 222 so that the valve 222 simply controls the flow of an increment of the water in pipe 224. Secondly, in the event of a shut down of the automatic control system, it may be opened completely so that the water is entirely under the control of

valves

84, 85, 86, 94, 95 and 97. 7

Furthermore, the automatic control of the water by valve 222 does not preclude the utilization of the

valves

84, 85, 86, 94, 95 and 97 for balancing the distribution of the water, as described above.

It will be obvious to those skilled in the art that many variations may be made in the embodiments here chosen for the purpose of illustrating the present invention without departing from thescope thereof as defined by the ap-. pended claims.

We claim:

1. In a continuous casting machine, a rotatable shaft, an inner circular flange carried by said shaft for rotation therewith, an outer circular flange spaced from said inner flange, spring means connecting said outer flange to said inner flange, and an annular casting member releasably carried between said inner flange and said outer flange, said annular casting member protruding outwardly of the peripheries of said outer flange and said inner flange and having a contniuous casting cavity about its outer periphery.

2. In a continuous casting machine, a rotatable shaft,

the motor 205 for causing it to rotate in an opposite direction.

As seen in FIG. 6, a linkage 220 is provided between the motor 205 and the brush 207 whereby, when motor 205 rotates, it moves the brush 207 along the resistor 208 in a direction for zeroizing the main control circuit. Thus, when the main control circuit is balanced, the movement of the brush 207, the motor 205 will be stopped.

When the pyrometer is reading a large temperature differential from the prescribed temperature, it generates a relatively high potential which requires greater movement of brush 207 to balance. Therefore, motor 205 will be rotated to a greater extent before brush 207 is properly positioned to return the main control circuit to a zero potential. It is now seen that the rotation of motor 205 is proportionally responsive to the surface temperature of rod 53 as read by pyrometer 200.

The motor 205 is connected to and controls, via linkage 221, .a main control valve 222. The main control valve 222, together with a manual bypass valve 223 is interposed in the line of a main pipe 224 from a source of coolant under pressure, such as water from a water main (not shown). The pipe 224 leads to the various

manual control valves

84, 85, 86, 94, 95 and 97.

Operation From the foregoing description, the operation of the present machine should be apparent. It is suitable for the continuous casting of quite a number of molten metals into rods. Specifically, the machine is suitable for casting aluminum, copper, zinc, lead and alloys thereof. The operation of the machine, therefore, will be described with respect to copper, since this is by far the more dilficult metal to cast in a form which may be reduced to wire size, and presents a novel way of casting copper. When utilizing the machine of the present invention for casting a continuous copper rod or bar, such as rod 53, it is desirable that the rod 53 be delivered from the machine as hot as possible without danger of the metal being molten within the central portion thereof, when the rod 53 is delivered to a rolling mill (not shown). Thus we have found that the copper rod 53 should have a surface temperature (as measured by pyrometer) when it emerges from the machine, of approximately 1750 F. and between the range from approximately 1600 F. to approximately l8-,50 F. Above approximately 1980 F. copper is in a molten state and hence a substantially lower surface temperature should be maintained so as to assure that essentially no molten metal exists in the core or central portion of the rod 53.

When the machine is to be operated, the shaft 10 is rotated in clockwise direction, as viewed in FIG. 1, at a speed such as to impart a peripheral velocity to the casting member 30 of between 30 and 60 linear feet per minute. The belt 50 is driven by the casting wheel at a like speed and circumscribes from approximately 45 to approximately 225 of the casting member 30. The belt converges toward the casting member 30 at the 45 inlet position and diverges therefrom at the 225 outlet position. Next, the valves of the cooling system are opened after molten copper is introduced into the groove 31.

It will be remembered that the third stages'of the internal cooling system, i.e., the cooling from 270 to 360 of arc of the casting member 30, is for the purpose of reducing the temperature of the upper increments of the casting member 30. Preferably the temperature is reduced to a temperature of from 400 to 450 F. The purpose of reducing the temperature of the upper increments of the casting member 30, immediately prior to the time that it receives the molten metal, is to increase the life of the casting member 30 and to present a relatively cool surface to the molten metal. ,The casting member 30, however, should be maintained at a temperature in excess of the 1 0 boiling point of the coolant, so that the casting cavity 31 i is dry when it receives the molten metal.

During the period in which the belt 50 is not in contact. with the casting member 30, the casting cavity 31 is open and the inside surface of the belt 50 is accessible. A part ing or releasing agent is continuously applied to the insidr surface of belt 50 and to the surface of the casting cavity. 31 so that the resulting cast metal rod 53 will readily par. from the casting cavity 31. While a number of releasing or parting agents are available, we recommend that. soot be employed to coat the casting cavity 31 and the inside surface of the belt 50 immediately prior to the time that these members receive the molten metal.

At the 45 position of casting member 30, the molten metal, such as molten copper, is fed from the pot 51,; through the spout 52, into the entrance or inlet of the tubular member formed by the convergence of the belt 50 and the casting cavity 31. The metal is prevented from flowing out of the casting cavity 31 by the belt 50 which closes the open side thereof. Hence the molten. metal runs down the right side of the casting cavity, as viewed in FIG. 1, and is solidified so as to build up a base for receiving additional molten metal. When such a base is built up, the molten metal can be received continuously in the inlet of the casting cavity 31. The first stage cooling, i.e., the cooling from 0 to 13:5" of the arc of the casting member 30, cools the molten metal, i.e., copper, from approximately 2200 F. (the temperature at which the molten metal is introduced into the casting cavity 31) to a temperature of approximately 1980 F., at which time the copper commences to solidify. This is accomplished in only a few seconds after the copper is received at the inlet.

i is solidified slowly,

The purpose of cooling the metal rapidly is to convert the molten metal into a solid having as small a grain structure as is feasible and to prevent internal voids due. to shrinkage of the metal upon cooling slowly.

As mentioned above, the prior art bar which is cast horizontally in a casting cavity, usually has a density of approximately 8.47 to approximately 8.59 and is subsequently rolled and drawn into the wire having the density of from 8.87 to 8.94. The prior art bar, as cast, is cooled relatively slowly so that the gases therein create a fiat or crown set to the upper surface, rather than a concave set or shrinkage cavity. The bar having a concave upper surface is difficult to roll because of the sharp edges at the upper surface.

Contrary to prior art beliefs and practices, the copper cast in the machine of the present invention is cooled quickly enough to produce a casting having an average overall density of 8.83, i.e., a density between approximately 8:75 and approximately 8.89. This copper rod has few, if any, voids or gas holes and essentially no sponge-like structure as would normally be found in horizontally cast copper.

The copper utilized in either case is 99.90%+ pure copper, the major portion of the impurities therein being oxygen in the form of copper oxide. Tlhere also are trace amounts of hydrogen and sulphur contained in the molten present invention contemplates metal. The process of the the freezing or solidfying of the molten metal from approximately 2200 F. down to below 1980 F., i.e., to approximately 1750 F. within a very short copper rod which is essentially free of any voids. Theo reticallly, by utilizing such a procedure the oxygen in the copper oxide is not given suflicient' time to disassociate and/or combine with the hydrogen or sulphur to produce a gas. a

While the reaction which has taken place, when copper is not understood completely by us, it has been suggested that the oxygen of the copper oxide combines with trace amounts of sulphur so as to produce sulphur dioxide, and with trace amounts of hydrogen to produce water vapor. Of course, some free oxy- I period of time, appmoximately two seconds, so as to produce a dense a circular inner flange mounted on said shaft for rotation therewith, an annular flange yieldably mounted on said inner flange, an annular casting member carried between the peripheries of said flanges and protruding outwardly therebeyond, said casting member having a continuous outwardly opening casting cavity in the outer periphery thereof, a continuous metal belt partially encompassing said casting member and converging toward and diverging from the outer periphery of said casting member, said belt closing the outer side of casting cavity between the positions of convergence and divergence of said belt, means for introducing molten metal into said cavity adjacent the position where said belt converges toward said casting member, a plurality of circumferentially spaced nozzles disposed adjacent the inner periphery of said casting member, conduit means leading from a source of coolant to said nozzles for supplying controlled amounts of coolant to said nozzles, a pair of groups of side nozzles disposed adjacent to the sides of said casting member for cooling that portion of said casting member which is partially encompassed by said belt and a pair of pipes leading respectively to said groups of said side nozzles.

3. In a continuous casting machine, a rotatable shaft, a circular inner flange mounted on said shaft for rotation therewith, an annular flange yieldably mounted concentrically on said inner flange, an annular casting member carried between the peripheries of said flanges and protruding outwardly therebeyond, said casting member having a continuous outwardly opening casting cavity in the outer periphery thereof, a continuous metal belt partially encompassing said casting member and converging and diverging from the outer periphery of said casting member, said belt closing the outer side of said casting cavity between the positions of convergence and divergence of said belt, a plurality of groups of circumferentially spaced nozzles disposed adjacent the inner periphery of said casting member for directing coolant outwardly and circumferentially toward said inner periphery, a plurality of pipes leading from a source of coolant respectively to said groups of nozzles for supplying controlled amounts of coolant to each of said groups of nozzles, a pair of groups of side nozzles disposed adjacent to the sides of said casting member for cooling that portion of said casting member which is partially encompassed by said belt, a pair of pipes leading respectively to said groups of said side nozzles, a group of belt cooling circumferentially spaced nozzles disposed in an arcuate path outwardly adjacent that portion of said belt which partially encompasses said casting member, a pipe for supplying coolant to said belt cooling nozzles, control means for controlling the amount of coolant fed to each group of nozzles, and means for feeding molten metal into the said casting cavity at a position adjacent the position at which said belt converges toward said casting member.

4. In a casting machine; an annular member having an inner surface, an outer surface, two side surfaces extending between said inner surface and said outer surface, and a casting groove in said outer surface; closing means for closing a length of said casting groove so that said closing means and said casting groove define a mold to receive molten metal; support means for supporting and rotating said annular member about an axis so that segments of said mold move along an arcuate path; a header having a chamber positioned within said inner surface of said annular member; means for dividing said chamber into a plurality of compartments disposed in sequence along said path; means for providing a coolant to each of said compartments; and cooling means for discharging said coolant from each of said compartments against said inner surface of said annular member.

5. The casting machine of claim 4 wherein at least two different quantities of said coolant are simultaneously 14 discharged from said compartments against said inner surface of said annular member. 7

6. The casting machine of claim 5 wherein said difierent quantities are independently variable. I

7. The castings machine of claim 5 wherein one of said quantities is applied at an initial portion of said path and is greater than the other of said quantities.

8. The casting machine of claim 7 wherein said one of said quantities is sufiicient to cool molten metal in said mold at a rate greater than any rate elsewhere along said path.

9. The casting machine of claim 4 including a plurality of fins extending from said inner surface of said annular member toward said cooling means for discharging said coolant from each of said compartments.

10. The casting machine of claim 4 wherein said cooling means for discharging said coolant from each of said compartments include a plurality of nozzles positioned to discharge said coolant from said compartments against said inner surface of said annular member.

11. The casting machine of claim 4 wherein said cooling means for discharging said coolant from each of said compartments includes a plurality of nozzles positioned to direct jets of said coolant from said compartments against said inner surface of said annular member.

12. The casting machine of claim 11 wherein said jets are directed in paths which are angularly disposed to said inner surface of said annular member.

13. The casting machine of claim 11 wherein said jets are directed in paths inclined to said inner surface of said annular member in the direction in which said inner surface moves as said angular member is rotated about said axis by said support means.

14. The casting machine of claim 4 wherein said means for dividing said chamber into a plurality of compartments is a plate positioned within said chamber to divide said chamber.

15. The casting machine of claim 4 including second cooling means disposed adjacent said annular member for applying said coolant to one of said side surfaces of said angular member, and third cooling means disposed adjacent said annular member for applying said coolant to the other of said side surfaces of said angular member.

16. The casting machine of claim 15 including means for selectively varying the quantity of said coolant applied to said one of said side surfaces .by said second cooling means independently of the quantity of said coolant applied to said other of said side surfaces by said third cooling means.

17. The casting machine of claim 15 including fourth cooling means disposed adjacent said annular member for applying said coolant to said closing means.

18. The casting machine of claim 17 including means for varying the quantity of said coolant applied by said fourth cooling means independently of the quantity of said coolant applied by said second cooling means, the quantity of said coolant applied by said third cooling means, and the quantity of said coolant applied by said cooling means for discharging said coolant against said inner surface of said annular member.

19. The casting machine of claim 4 including spray means disposed adjacent said annular member for spraying said coolant on said closing means.

20. The casting machine of claim 19 wherein said spray means includes an arcuate tubular member having a plurality of nozzles along its length positioned to direct jets of said coolant against said closing means.

21. The casting machine of claim 20 wherein the paths of at least some of said jets are inclined to said closing means in the direction in which said angular member moves as said annular member is rotated about said axis by said support means.

22. The casting machine of claim 21 wherein the paths of others of said jets are inclined to said closing means in a direction opposite to said direction in which said 15 16 annular member moves as said annular member is rotated 2,743,492 5/1956 Easton 22 -79 about sard axrs by sard support means. FOREIGN PATENTS References Cited by the Examiner 764,193 12/ 1956 Great Britain. UNITED STATES PA N S 5 861,273 2/1961 Great Britain.

944,370 12/ 1909 Monnot 22200.1 X T 2,206,930 7/1940 Webster 22 57 3 J. SPENCER OVERHOLSER, Pnmary Exammer.

2,246,907 6/1941 Webster 22--57.3 X R. S. ANNEAR, Assistant Examiner.