US3128513A - Moldless metal casting process - Google Patents

Description

April 14, 1964 J, w, CHARLTON ETAL MOLDLESS METAL CASTING PROCESS 3 Sheets-Sheet 1 Filed'March 29, 1961 3 Sheets-Sheet 2 .1. w. CHARLTON ETAL MOLDLESS METAL CASTING PROCESS IAIAI fififim April 14, 1964 Filed March 29, 1961 April 14, 1964 J. w. CHARLTON ETAL MOLDLESS METAL CASTING PROCESS 5 Sheets-Sheet 3 Filed March 29, 1961 United States Patent ()fiice 3,128,513 Patented Apr. 14, 1964 3,123,513 MULDLESS METAL CASTING PROCESS Joseph W. Charlton, Liberty St., Madison, Conn, and John L. Cotsworth, 1400 Unquowa St., Fairfield, Conn. Filed Mar. 29, 1961, Ser. No. 118,209 3 Claims. ((31. 22-200.1)

This invention relates generally to casting metal, and more particularly to continuous casting of metal into strip or bar stock.

The present invention is concerned with continuous casting of metal into strip or bar stock especially, though not exclusively, of the smaller gauges. In continuously casting metal into strip or bar stock heretofore, the molten metal was led into a mold-like passage or aperture in which it was shaped and also sufficiently solidified to retain its given shape on emerging therefrom. Some of the prior installations for thus continuously casting metal into strip or bar stock are of a type having rotating rolls or endless traveling belts, or a combination of both, which form the mold-like passage so that the walls of the latter travel advantageously with the cast metal therein. The prior installations of this mobile mold type are, among all prior installations for the same purpose, easily the most efiicient in performance and production capacity and, furthermore, produce strip and bar stock of the smallest gauges hitherto attainable. Yet, while prior installations of this type are certainly successful in a number of respects and are economically attractive because they eliminate in the formation of cast strip or bar stock conventional expensive ingot casting, reheating and breakdown hot-rolling, they do have some inherent and more or less severe operational limitations. Thus, the prior installations of this type do not readily lend themselves to the casting of stock of many smaller gauges or stock of much smaller or more complex sections for which there is great demand wherefore the stock they produce requires in many instances more or less extensive size reduction with ensuing increase of the cost of such stock at their finished gauges. Further, the rate of stock production of these prior installations is limited rather severely, owing to an inherently low heat-exchange rate between their mobile molds and the cast stock therein despite best possible cooling of the molds on the one hand, and the requirement that such stock must remain confined in the mobile molds until sufiiciently solidified to retain its shape on the other hand. Also, owing to inherent limitations in the amount of heat to which the mobile molds may constantly be subjected without sustaining damage or undergoing disintegration, the prior installations of this type do not lend themselves to casting metals of very high melting point. Moreover, these prior installations involve a relatively heavy initial capital investment and also rather high maintenance cost which are inevitably reflected in the cost of the produced stock.

It is among the more important objects of the present invention to devise a process of casting metal into longitudinal stock which in practice permits stock casting much beyond the aforementioned limits of the prior installations of the mobile-mold type in the respects of minimum stock sizes, rate of stock production and melting points of the cast metals, and which involves equipment of an initial capital investment and maintenance cost much below those of the prior installations.

It is another important object of the present invention to devise a process of casting metal into longitudinal stock of uniformly shaped section in the absence of any mold, fixed or mobile, thereby to eliminate in the casting of uniform stock the one factor which hitherto imposed the aforementioned casting limitations and largely accounted for the relatively high cost of the casting equipment.

It is a further important object of the present invention to apply the aforementioned moldless casting process to the formation of stock of widely different sections and of strip, bar or tubular type, as well as in relatively short sections or in continuous lengths.

Another important object of the present invention is to provide in the aforementioned moldless stock casting process for the formation by the cast metal of its own mobile mold, by forcing the metal in a continuous molten stream from a nozzle directly into a fluid bath in which the molten stream is chilled so rapidly as to be transformed, prior to possible scattering, into initial stock with an outer plastic crust of suflicient tensile strength and flexibility to contain the molten metal therewithin and be shaped crosssectionally by the elfects of surface tension and pressure of the contained molten metal, with the crust and contained molten metal being on continued cooling transformed into unitary solid stock.

A further object of the present invention is to provide in the aforementioned moldless stock casting process for more extensive shaping of the stock section, by causing the initial stock with the plastic crust to gravitate into a forming groove in a moving transport and be carried therein for a sufiicient length of time to be shaped into closest possible conformity with the groove contour that can be achieved by the eifects of surface tension and pressure of its metal, and at a rate to preserve the continuity of the initial stock with the continuous molten metal stream, with the shaped stock being led off the transport at a stage of its solidification at which it is no longer self-deformable.

It is another object of the present invention to provide in the aforementioned moldless stock casting process for still more extensive shaping of the stock section, by passing through companion forming rolls the initial stock with the plastic crust at a stage of its solidification at which it will smoothly take the shape of the forming grooves in the rolls without becoming ruptured or causing increasing pile-up of metal at the bite of the rolls.

It is a further object of the present invention to pro vide in the aforementioned moldless stock casting process for ready control over the size of the stock within Wide limits and with the same metal-discharge nozzle of a given size, by causing the initial stock with the plastic crust to gravitate onto a moving transpiort'and be carried thereby at least until the stock is sized, and by regulating the transport velocity so that it may be the same as, or may be different, more or less, from, the discharge velocity of the molten metal stream. In thus regulating the transport velocity, the plastic crust of the initial stock will in any event act as a resilient pipe in which to distribute the molten metal of the stream, with the rate of distribution of the molten metal in the resilient pipe-like crust Ion the moving transport depending on the velocity difiierential of the transport and the molten metal stream at its discharge. Thus, if the transport velocity is lower than the dischamge velocity of the molten stream, molten metal will dam up in the resilient stock crust on the transport and swell the stock into larger size than that of the molten stream at the discharge nozzle. Converse- #ly, if the transport velocity is higher than the discharge velocity of the molten stream, the resilient stock crust will on its immediate approach to and carrying engagement with the moving transport be elongated and undergoes compensatory sectional con-traction, with the molten metal being evenly distributed therein to form stock of smaller size than that of the molten stream.

It is another object of the present invention to adapt the aforementioned moldless stock casting process for the production of tubular metal stock, by discharging a molten metal stream through a ring-shaped nozzle, and introducing through the center of the nozzle into the interior of the molten stream a gas under sumcient compression to preserve the tubular structure of the stream until the metal thereof is sutficiently solidified to prevent collapse of its tubular structure.

Other objects and advantages will appear to those skilled in the art from the following, considered in conjunction with the accompanying drawings.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

FIG. 1 is a longitudinal section through apparatus for casting metal stock according to a featured process which embodies an important part of the present invention;

FIG. 2 is a cross-section through the same apparatus as taken on the line 2-2 of FIG. 1;

IFIG. 3 is an enlarged fragmentary section through the same apparatus, demonstrating a prominent step in casting metal stock in accordance with the featured process;

FIGS. 4, and 6 are sections taken on the lines 4--4, 5--5 and 6-6, respectively, of FIG. 3;

FIG. 7 is a top view of apparatus for casting metal stock according to a modified process of the present invention;

FIG. 8 is an enlarged section taken on the line 8-8 of FIG. 7;

FIG. 9 is a longitudinal section through apparatus for casting metal stock according to another modified process of the resent invention;

FIGS. 10, 11 and 12 are enlarged sections taken on the lines Iii-14), ill-11 and 12-i2, respectively, of FIG. 9;

FIG. A is a section through different metal stock cast in accordance with a process of the present invention;

FIG. HA is a fragmentary section through apparatus in which the stock of FIG. 10A is cast;

FIG. 13 is a fragmentary longitudinal section through apparatus for casting metal stock in accordance with a further modified process of the present invention;

FIGS. 14, 15 and 16 are enlarged fragmentary sections taken on the lines 14-44, 1515 and l*616, respectively, of FIG. 13;

'FIG. 17 is a fragmentary longitudinal section through apparatus for casting metal stock in accordance with another modified process of the present invention;

FIG. 18 is an enlarged section through part of the apparatus of FIG. 17;

FIGS. 19 and 20 are sections taken on the lines 19-19 and 20-20, respectively, of FIG. 18;

FIGS. 2'1 and 2-2 are sections through parts of apparatus modified from that of FIG. 17;

FIG. 23 is a fragmentary section through apparatus for casting metal stock in accordance with a further modified process of the present invention;

FIG. 24 is a fragmentary longitudinal section through apparatus for casting metal stock in accordance with another nrodified process of the present invention;

FIG. 25 is a longitudinal section through apparatus for casting metal stock in accordance with a further modified process of the present invention;

FIG. 26 is a fragmentary longitudinal section through apparatus for casting tubular metal stock in accordance with still another modified process of the present invention; and

FIG. 27 is an enlarged section taken on the line 27--27 of FIG. 26.

Referring to the drawings, and more particularly to FIGS. 1 to 3 thereof, the reference numeral 30 designates apparatus for casting longitudinal metal stock s of shaped section. The apparatus 30 comprises, in the present instance, a melting furnace 32, a fluid coolant bath 34 and stock-retracting rolls 36.

The melting furnace 32 comprises in this instance a shell 38 with an inner refractory lining 40 which provides a melting chamber 42 in communication with a discharge nozzle 44. Embedded in the lining 48 are heating means which in this instance are electric heater elements 46 of Calrod type. The furnace 32 may be supported in any suitable manner (not shown) above the fluid bath 34.

The fluid bath 34 is, in the present instance, a suitable liquid L in a tank 48 which contains elements 50 for maintaining the liquid bath at proper operating temperature.

Stock s of shaped section is cast in the present apparatus in accordance with a featured process which basically involves casting a molten metal stream directly into a fluid coolant bath, and chilling the metal stream in the bath so that during an initial stage of its transformation from molten state into solid state the uninterrupted mol ten stream is transformed into initial stock of such transitory plasticity as to preserve its continuity with the molten stream and be also shaped into the stock section by the effects of surface tension and pressure of its metal, with the initial stock thus formed being further solidified in the bath preferably to its fully solid state.

Prior to casting stock s in the present apparatus in accordance with this process, the furnace chamber 42 is charged with solid metal to-be-cast, whereupon the furnace 32 is heated to melt the metal therein, the nozzle 44 being meanwhile closed at its discharge end 52 in any suitable manner. The liquid bath 34 is also brought to proper operating temperature. Once the metal in the furnace has melted, an operating run of the apparatus may be started by opening the nozzle 44 for discharge therefrom of molten metal M in a continuous stream S. The molten metal stream S is discharged directly into the coolant bath which in the present instance also includes atmospheric air over the short distance which the molten metal stream traverses before plunging into the liquid bath 34. After a leading length of the metal in the bath 34 has solidified, it is grasped with steel tongues and led between the driven rolls 36 at a rate to preserve the continuity of the cast metal in the bath with the continuously discharging molten metal stream S. Once the driven rolls 36 take over the retraction of the stock from the bath, the operation continues uninterruptedly as long as molten metal is discharged from the nozzle 44 in a continuous stream, additional solid metal being from time to time dumped into the melting chamber 42 to continue the uninterrupted discharge of molten metal in a continuous stream as long as desired.

The discharge velocity of the molten metal stream S at the nozzle 44 will determine the rate of linear production of stock s. Of course, the discharge velocity of the molten metal stream depends on the size of the discharge orifice 54 of the nozzle 44, on the viscosity of the particular molten metal, and in the present example also on the head of molten metal in the furnace chamber 42. In any event, the discharge velocity of the molten metal stream is kept sufficiently high to prevent scattering of its metal until the molten stream has initially been solidified in the coolant bath sufficiently to withstand disintegration. Also, in view of the relatively high melting points of metals in general, and in further view of the usual requirement that the coolant bath be chemically non-reactive with the metal being cast, the liquid of the bath is usually other than water, and is most frequently a molten salt of a melting point sufiiciently lower than that of the metal being cast for cooling the latter at the proper rate, requiring heating of the bath for melting the salt and keeping it in liquid state. Under the circumstances, the elements 50 in the tank are heating elements of any suitable kind.

In discharging the molten metal stream S into the coolant bath of proper temperature, the molten stream is chilled sufficiently rapidly, starting with its emergence from the nozzle 44, to be soon transformed into initial stock s of such transitory plasticity as to preserve its continuity with the molten metal stream S and be shaped into the stock section by the elfects of surface tension and pressure of its metal. Thus, the chilling of the molten metal stream in the coolant bath almost immediately freezes on the molten stream an outer skin or crust c of increasing thickness (FIG. 3). This continuously forming crust c, while plastic, has suflicient tensile strength to contain the molten metal therewithin and preserve its continuity with the molten stream S, and is sufficiently flexible to be cross-sectionally deformed uniformly, i.e., shaped into the desired section of the stock, by the effects of surface tension and pressure of the contained molten metal. While in FIG. 3 the crust c and molten metal M therein are shown separated by a mere demarcation line between them for simplicity of illustration, it stands to reason that there is actually a transition zone between the outer crust and contained molten metal in which the plasticity of the crust approaches the fluidity of the molten metal. Thus, with the discharge orifice 54 of the nozzle 44 being circular in the present example, the molten metal stream S will also be circular in section (FIG. 4). However, as the molten metal of the stream S reaches the station A (FIG. 3), which is at a sufficient distance from the nozzle 44 at which the molten metal would scatter or already have started to scatter, there is already formed on the molten metal stream the crust c which gives way to the surface tension and pressure of the contained molten metal by horizontal elongation and vertical contraction into the slightly oval section shown in FIG. 5. This shaping of the stock section by the effects of the surface tension and pressure of the molten metal on the crust c proceeds further until they cease to have any further shaping effect on the crust c with increasing depth and decreasing plasticity of the same. Thus, the shaping of the stock section may be completed when the molten metal of the stream reaches the station B, for example, at which the finish-shaped stock section is of the exemplary, more pronounced, oval outline shown in FIG. 6. Beyond this station B, the initial stock s will soon be fully solidified, in the present example at the station C (FIG. 3). The molten metal stream S is discharged from the nozzle 44 in a downward direction at an inclination to the horizontal so that the cast stock s, s will gravitate toward and advantageously to the bottom of the tank 48 on which it is permitted to slide for some distance before being led therefrom to the retracting rolls. In this way, the drag by the rolls 36 on the cast stock s for its retraction from the bath 34 may readily be regulated to avoid severance of the continuously forming intial stock s from the continuously discharging molten metal stream S.

In casting metal stock of shaped section in accordance with this process, the molten metal of the continuously discharging stream forms in effect its own mobile mold, in the form of the plastic crust c, in which the remaining molten metal of the stream is cast, with this mobile mold and the molten metal therein being on their continued cooling and, hence, solidification transformed into unitary solid stock.

To give some indication of actual operating conditions, there is given, by way of example and by no means by way of limitation, the following data of one of the earliest performances of test apparatus similar to that of FIG. 1. Thus, the furnace chamber had a diameter of roughly 5" and was charged with aluminium of a melting point of 1220 F. and of a freeze point of 1190 F., with the furnace chamber being heated to about 1250 F. The nozzle had a discharge orifice of .125 in diameter and the head of molten aluminum in the furnace chamber was from 5" to 7". The molten salt bath was kept at a temperature of between 980 and 990 F. The molten aluminum discharged from the nozzle in a continuous stream into the coolant bath at a velocity which produced ap- 5 proximately 13 feet of stock per minute. The cast stock, being aluminum wire, was fairly uniform in the shape and size of its section, its shape being oval but its ovality deviating so little from a circular outline as to be clearly perceptible only under weak magnification. The aluminum wire thus cast was sufliciently uniform in section to be useable for many applications in which uniformity of the wire gauge is not a prime requisite, and a single draw of the cast wire through a die was found suificient to render the same fully acceptable for most applications requiring close tolerances in Wire gauge. The grain structure of the wire was characteristic of its moldless casting and remarkable for its fineness and uniformity from the outer periphery to the center thereof, springing from the direct chilling of the cast metal in the coolant bath without intervention of any mold walls. Also, the surface texture of the Wire was characteristic of its moldless casting, primarily by being splotched, unobjectionably but nevertheless sufficiently distinctly, to rule out its casting in a conventional mold, fixed or mobile.

Since undertaking the above described early test performance of the apparatus, many more test runs of the latter have indicated the wide versatility of the present casting process. Thus, this process lends itself to the casting of most any metal, including those of the highest melting points, and to the casting of stock of sectional sizes within wide limits, as well as of many different shaped sections. These test runs of the apparatus have also indicated that there are no critical factors involved in casting stock according to the present process. Thus, the temperature of the coolant bath may vary relatively idely for the same stock production without adversely affecting the same. For example, it has been noted that the zone of initial stock formation, being from the nozzle 44 to station B in the exemplary installation 30 (FIG. 3), will shorten or lengthen with different coolant bath temperatures, all other conditions being alike. Also, different discharge velocities of molten streams of different metals from nozzles of different orifice sizes and at different heads of molten metal in various available test equipment, were readily controlled simply by interposing in the discharge orifice of the nozzle a constriction whenever this was required to prevent such free runaway of the molten metal as would defeat any orderly casting thereof.

Reference is now had to FIG. 7 which shows modified apparatus 30a for casting metal stock s of shaped section in accordance with the present featured process. The present apparatus 30a comprises a melting furnace 32a With a nozzle 44a through which to discharge molten metal M into a fluid bath 34a. The fluid bath is in the present instance a liquid L in a ring-shaped tank 60 which is driven about its axis x by being mounted on spider arms 62 on a journalled vertical shaft 64 with a bevel gear 66 that is in permanent mesh with a power-driven companion gear 68. The tank 60 has suitable elements (not shown) for keeping the liquid L at proper operating temperature. The molten metal stream S is discharged from the nozzle 44a directly into the liquid bath, the nozzle being to this end submerged with its discharge end in the liquid L (see also FIG. 8). The continuously forming stock gravitates toward and onto the bottom 70 of the tank 60 and is carried thereon toward power-driven companion rolls 72 which retract the finished stock from the liquid bath.

The continuous casting of metal stock in the present apparatus 30a may in all respects be like the described casting of stock in the apparatus of FIGS. 1 to 3, except that in the present apparatus the discharge nozzle 44a is submerged in the liquid bath which is preferably chemically non-reactive with the metal being cast to protect the same until completely solidified. Also, the continuously forming stock in the liquid bath is in the present apparatus carried or transported away from the nozzle 44a by the driven tank 60 the moment it gravitates onto the bottom 70 thereof, thus obtaining, by the simplest control over the drive of the tank, the least tension in the initial stock s by virtue of continuous stock retraction by the rolls 72 and, hence, readily preserving the continuity of the continuously forming initial stock with the continuously discharging molten metal stream. The present apparatus is, therefore, particularly advantageous for casting stock of smaller sections. The fairly close proximity of the discharge end 52a of the nozzle 44a to the tank bottom '70 is further advantageous since the initial stock s with its plastic crust may very shortly after the start of its formation gravitate onto the tank bottom and thus leave the short length of the initial stock extending to the tank bottom with minimum tension for its assured continuity with the steadily discharging molten metal stream. Thus, there has been cast quite successfully in a test installation similar to the present apparatus 39a wire of a diameter of about .015" in continuous lengths. On the other hand, bar or rod stock of much larger sections, for example stock of oval section with long and short axes of .3125 and .25, respectively, has been cast in continuous lengths equally successfully in the same test installation. Moreover, Wire of .015 diameter and in continuous lengths has successfully been cast in this test installation on discharging the continuous jet or stream of molten metal into a non-cooled water bath without any noticeable detrimental effects on the cast stock.

The above-described shaping of the section of stock cast in accordance with the present process is, of course, limited by the shaping effects on the initial stock of the surface tension and pressure of its metal. However, the shaping of the section of cast stock may readily be carried considerably further with the aid of outer forming surfaces which at their contacts with the initial stock compel the same to deform into conformity with these surfaces. Stock may thus be cast and shaped, according to the process as featured but modified in this shaping respect, in modified apparatus 3 of FIG. 9. This apparatus may in most respects be like the apparatus 3d of FIG. 1 in the matter of the melting furnace 32b, the liquid bath 34b and the stock-retracting rolls 361), except that the nozzle 44b is preferably submerged in the liquid bath 3412. For shaping cast stock according to this modified process, the apparatus 3% comprises a conveyor 8% of endless chain-type alternate links 32 of which are provided with stock-shaping surfaces 84. The chain-type conveyor 80 is led over spaced sprockets 36 on suitably journalled shafts 88 one of which is power-driven to drive the top run of the conveyor in the direction of the arrow 99. The alternate links 82 of the conveyor, which are joined by conventionl links 92, provide stock-transports 94 which are longitudinally grooved at 96 to provide the stock-shaping surfaces 84 (see also FIGS. 11 and 12), with the transports 94- and grooves 96 of the links 82 being continuous with each other in the straight chain runs between the sprockets 86.

Assuming that the desired section of the stock to-becast be as nearly circular as possible, the shape of the orifice of the nozzle 44b may be like or similar to that of the discharged molten metal stream in FIG. 10, i.e., oval with its longer axis extending in a vertical plane. In operation, the molten metal stream issuing from the nozzle 44b will quickly start its transformation into the initial stock s with the plastic crust c, with the initial stock being during its approach to the top run of the conveyor 80 pro-shaped from the section shown in FIG. 10 to that shown in FIG. 11 by the effects of surface tension and pressure of its metal. The initial stock s, while still in a self-deformable state, gravitates onto the top run of the driven conveyor 86, and more particularly into the continuous grooves 96 of the links 82 thereof wherein it will be finish-shaped by the groove surfaces 84 (FIG. 12) while being transported therein. In thus finish-shaping the stock, the grooves 96 serve in a sense as a mobile mold in which the stock is shaped only to the extent permitted by the surface tension and pressure of its metal. In the present exemplary casting operation, the stock will have reached the end of its plastic selfdeformation state when spreading into line contact, more or less, with the sidewalls 84 of the grooves 96 (FIG. 12).

More extensive shaping of stock in accordance with the modified process just described may also be achieved in apparatus which for finish-shaping of the stock may have structurally simpler and less costly provisions than the chain-type conveyor 86 of PEG. 9. Thus, the apparatus 39a of FIG. 7 has in the bottom of its tank 60 an annular groove formation 61. for interchangeable reception of rings with annular stock-shaping grooves of various sections (not shown).

With the adaptability of the featured process to the casting of rod or bar stock already amply demonstrated, PIGS. 10A and 11A demonstrate its ready adaptability to the casting of metal strip in continuous lengths or shorter sections. Thus, metal strip may be cast according to the featured process in apparatus which may in all respects be like that of FIG. 9, except that the section of the discharge orifice of the nozzle is rectangular so that the initial strip stock 5 is at the beginning of its formation of the exemplary section shown in FIG. 10A, and the grooves 96 in the chain links 82 are correspondingly wider (FIG. 11A). Of course, it is fully within the purview of the present invention to cast metal strip according to the present invention without benefit of forming grooves, such as the grooves 96' in FIG. 11A.

The shaping of metal stock cast in accordance with the featured process may be carried still further by subjecting the stock to the action of companion forming rolls, such as the rolls 1% in FIGS. 13 and 16, for example. These rolls 1% have complemental peripheral grooves 102 of combined hexagonal section for shaping the stock section accordingly. The rolls 1% are mounted on suitably journalled shafts 16 3- both of which are driven to move the stock therebetween in the direction of the arrow 106 (FIG. 13). The rolls 1% are submerged in the liquid bath 34c of casting apparatus 36c which in all other respects may be like the apparatus 3d of FIG. 1. In operation, the continuously discharging molten metal stream is continuously transformed into initial stock s which on its pass toward the forming rolls 1% is progressively preshaped (FIGS. 14 and 15) by the effects of surface tension and pressure of its metal. The stock reaches the bite of the rolls 1% at a stage of its progressive solidification at which it will readily be reformed by the rolls into the exemplary hexagonal section (FIG. 16) without becoming ruptured or causing pile-up of metal just ahead of the bite of the rolls which would spoil the operation.

The driven forming rolls liitl of FIG. 13 bring to mind the feasibility of using a single driven roll with a peripheral groove of any sectional shape and size in lieu of the chain-type conveyor with the stock-shaping grooves 96 in the apparatus 301) of FIG. 9. Thus, the relatively short duration of the transport of initial stock in the groove of such a single roll would in many stock casting operations be entirely adequate to finish-shape the stock.

While in the stock-casting operations described hereinbefore the rate of linear stock production is substantially equal to the discharge rate of the molten metal stream, FIGS. 17 and 18 show apparatus 30d for easting metal stock at a rate of linear production which is different from, and in this instance smaller than, the discharge rate of the molten metal stream S, with the size of the stock section being, however, larger than that of the discharge orifice of the nozzle 44 at substantially the same ratio at which the discharge rate of the molten metal stream is larger than the rate of linear stock production. The apparatus 30d may in all respects be like the apparatus 30b of FIG. 9, except that the stock-transport surfaces 116 on the links 82d of the driven conveyor fitld are plane rather than grooved. The operation of the present apparatus 30d is also the same as that of the apparatus 301) of FIG. 9, with the important exception that the conveyor 80d of the present apparatus is driven at a speed which is lower than the discharge velocity of the molten metal stream S at the nozzle 44d. The continuously discharging molten metal stream S will in the fluid bath 34d undergo its transformation into the initial stock s on its gravitation to and transport on the link surfaces 110 of the conveyor. Thus, the plastic crust will continuously form on the descending leg of the metal stream at a rate to preserve its continuity with the latter. However, since the plastic crust c will in its linear advance be slowed down when becoming seated on the transport surfaces 110 of the conveyor, its linear displacement with the latter is insufficient to make room for the ever onrushing crust c on the descending leg of the metal stream, compelling it into compensating pe ripheral displacement with ensuing peripheral swelling of the crust c shortly after coming to rest on the conveyor. The crust c on the descending leg of the metal stream acts like a pipe which conducts molten metal at a rate to continuously fill the peripherally expanded or stretched crust c on the conveyor. The shaping of the stock section takes place on the conveyor starting at the maximum expanded, exemplary circular, section of the initial stock s (FIG. 19) and ending with the exemplary oval shape (FIG. 20).

The casting of metal stock in accordance with the modified process just described is, of course, highly advantageous in that it affords, by the mere expediency of speed regulation of the conveyor, the casting of stock of widely varying sectional sizes with the use of the same metal discharge nozzle of a given size. For example, continuous metal stock of oval shape with transverse axes of .375" and .3125" has been cast successfully on discharge of the molten stream from a nozzle with an orifice of slightly over .0625" diameter.

The shaping of the sized section of metal stock cast in accordance with the modified process just described with reference to FIGS. 17 to 20, may be carried further by providing the stock-transport surfaces 110 with longitudinal grooves 112 (FIGS. 21 and 22) in which the initial stock .9 is shaped into stock s of roughly rectangular section (FIG. 22).

FIG. 23 shows the alternative casting of metal stock s of small section from a molten metal stream S of larger section, with the rate of linear stock production being accordingly larger than the discharge rate of the molten metal stream at the nozzle Me. In this exemplary operation, the conveyor 80a is driven at a rate considerably in excess of the discharge rate of the molten metal stream, with the plastic crust on the initial stock s on the transport surface little of the conveyor responding to the higher speed of the latter by longitudinal stretching and peripheral contraction.

FIG. 24 shows casting apparatus 30f which may in all respects be like the apparatus 30 of FIG. 1, with the important exception that the pressure of the molten metal at the nozzle 44 and, hence, its discharge velocity thereat may not only be regulated but also kept constant regardless of the head of molten metal in the melting chamber 42 To this end the top of the furnace shell 38) is arranged as a pressure dome 116 which through a conduit 118 is in communication with a source of compressed gas of a kind which preferably is chemically non-reactive with the molten metal M. The molten metal supply in the furnace chamber 42 is thus kept under constant pressure by the gas G in the dome 116, and this pressure may, furthermore, be changed at will by manipulating a suitable pressure-regulating valve (not shown) in the conduit 118. The dome 116 is provided with an opening 120 through which to charge the furnace chamber 42 with solid metal to-be-cast, with the opening 120 being normally closed by a sealed door 122.

While in the casting apparatus described so far the coolant bath is a liquid bath, FIG. 25 shows apparatus 30g in which the coolant is a gas G that is preferably chemically non-reactive with the cast metal, though it could conceivably be air where oxidation of the outer surface of the cast stock is not objectionable. To this end, the tank 48g is sealed to contain the coolant gas which is introduced through a conduit 124 that is in communication with a gas source. The melting furnace 32g extends with its lower nozzle end into the tank 48g in sealed fashion. The cast stock s is retracted from the tank 48g through a liquid trap 126.

Reference is finally had to FIG. 26 which shows apparatus 30h for casting tubular metal stock t according to a modified process. The present apparatus may in all respects be like the apparatus 30b of FIG. 9, with the important exception that there extends through the melting chamber 42h and into the orifice 54h of the nozzle 44h a tubular core 128 which together with the orifice 5411 forms a ring-shaped discharge opening 130 for the molten metal. The tubular core 128 is connected with a source of compressed gas, preferably through intermediation of a pressure-regulating valve (not shown) with the gas G being preferably non-reactive with the cast metal.

In operation, molten metal is constantly discharged through the ring-shaped opening 130 in a continuous tubular stream, and gas G of regulated compression constantly discharges from the. tubular core 128 into the tubular metal stream to preserve its tubular structure until solidified beyond plastic self-deformation. The constantly discharging tubular metal stream in the liquid bath 34h will immediately start its transformation into the initial tubular stock I." with the inner and outer plastic crust c, and descend onto the driven conveyor h on which its section is finished-shaped, preferably in grooves 96h in the transport surfaces 11% of the stock-carrying links 82h of the conveyor. The temperature of the gas G may also be regulated prior to its flow through the tubular core 128.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

What is claimed is:

1. The moldless process of continuously casting rod or the like stock of shaped section, which comprises discharging in non-vertical direction from a nozzle of a section different from the stock section into a fluid in a tank, a continuous stream of molten metal of higher specific gravity than the fluid with sufiicient force substantially to confine the molten metal in the fluid to the shape and size of the nozzle section; solely by the effects of surface tension and pressure of the metal of the stream gradually reshaping the section of the metal stream, by externally chilling the metal stream while passing through the completely enveloping fluid toward the tank bottom at an inclined approach thereto for gradual solidification at plastic self-deformation of the metal stream to the point where the metal stream is beyond disintegration on the hereinafter recited stock retraction; and retracting the substantially solidified stock on the tank bottom in a direction and at a rate to keep the metal stream at its inclined approach to the tank bottom and preserve the continuity of the stock with the molten metal stream.

2. The moldless process of continuously casting rod or the like stock of shaped section, which comprises discharging from a nozzle of a section diflerent from the stock section into a liquid in a tank a continuous stream of molten metal of higher specific gravity than the liquid in a downward direction inclined to the tank bottom and with sufficient force substantially to confine the molten metal in the liquid to the shape and size of the nozzle section; solely by the effects of surface tension and pressure of the metal of the stream gradually reshaping the section of the metal stream, by externally chilling the metal stream while passing through the completely enveloping liquid toward the tank bottom for gradual solidification at plastic self-deformation of the metal stream to the point where the metal stream is beyond disintegration on the hereinafter recited stock retraction; and retracting the substantially solidified stock on the tank bottom in a direction and at a rate to keep the metal stream at its inclined approach to the tank bottom and preserve the continuity of the stock with the molten metal stream.

3. The moldless process of continuously casting rod or the like stock of shaped section as set forth in claim 2,

in which the molten metal stream emerges from the nozzle submerged in the liquid.

References Cited in the file of this patent UNITED STATES PATENTS 1,137,199 Eyton Apr. 27, 1915 2,135,183 Junghans Nov. 1, 1938 2,298,348 CoXe Oct. 13, 1942 2,707,813 Dickson May 10, 1955 2,754,559 Fromson July 17, 1956 2,789,327 Corley Apr. 23, 1957 2,907,082 Pond Oct. 6, 1959

Claims (1)

1. THE MOLDLESS PROCESS OF CONTINUOUSLY CASTING ROD OR THE LIKE STOCK OF SHAPED SECTION, WHICH COMPRISES DISCHARGING IN NON-VERTICAL DIRECTION FROM A NOZZLE OF A SECTION DIFFERENT FROM THE STOCK SECTION INTO A FLUID IN A TANK, A CONTINUOUS STREAM OF MOLTEN METAL OF HIGHER SPECIFIC GRAVITY THAN THE FLUID WITH SUFFICIENT FORCE SUBSTANTIALLY TO CONFINE THE MOLTEN METAL IN THE FLUID TO THE SHAPE AND SIZE OF THE NOZZLE SECTION; SOLELY BY THE EFFECTS OF SURFACE TENSION AND PRESSURE OF THE METAL OF THE STREAM GRADUALLY RESHAPING THE SECTION OF THE METAL STREAM, BY EXTERNALLY CHILLING THE METAL STREAM WHILE PASSING THROUGH THE COMPLETELY ENVELOPING FLUID TOWARD THE TANK BOTTOM AT AN INCLINED APPROACH THERETO FOR GRADUAL SOLIDIFICATION

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