US2590311A - Process of and apparatus for continuously casting metals - Google Patents

Description

March 25, 1952 1. HARTERMETAL 2,590,311

PROCESS OF AND APPARATUS FOR CONTINUOUSLY CASTING METALS Filed Feb. 26, 1948 1o Sheets-Sheet 1 kg V 765 x i I I .1; J7 4 g Janna-Harder ATTORNEY March 25, 1952 l. HARTER ET AL 2,590,311

PROESS OF AND APPARATUS FOR CONTINUOUSLY CASTING METALS Filed Feb. 26, 1948 1Q Sheets-Sheet 2 fag.

Isaac Hdrter 41 Isaac HareI Jrd? 0151's E. Car/Jen fer INVENTORS ATTORNEY March 25, 1952 HARTER ET AL 1 2,590,311

PROCESS OF AND APPARATUS FOR CONTINUOUSLY CASTING METALS Filed Feb. 26, 1948' I 10 Sheets-Sheet 5 44 [saac Harrier Isa ac Ha/"ez; JKX 06 is R. Czrpezz zlez" INVENTORS ATTORNEY March 25, 1952 1. HARTER ET AL I 2,590,311

PROCESS OF AND APPARATUS FOR CONTINUOUSLY CASTING METALS Fi le'd Feb. 26, 1948 V '10 sheqts-sheet 4 INVENTQRS BY Wm ATTORNEY March 25, HARTER ETAL I PROCESS OF AND APPARATUS FOR CONTINUOUSLY CASTING METALS Filed Feb. "26, 1948 v 10 Sheets-Sheet 5 Isaac Harier [saac HariezJirJ Otis 1?. Carpet? ier INVENTORS ATTORNEY l. HARTER ET AL March 25, 1952 PROCESS OF AND APPARATUS FOR CONTINUOUSLY CASTING METALS i0 Sheets-Sheet 6 Filed Feb.. 26, 1948 0275 1Q Car 220261". INVENTORS BY ATTORNEY March 25', 1952 l. HARTER ETAL PROCESS OF AND APPARATUS F OR CONTINUOUSLY CASTING METALS Filed Feb."26, 194

10 Sheets-Sheet 7 VIII/III 76 wmm I j r fl 8 k0, r w c A a INVENTORS ATTORNEY March 25, 1952 HARTER ET AL 2,590,311

PROCESS OF AND APPARATUS F OR CQNTINUOUSLY CASTING IVIE'I'ALv Filed Feb. 26 1948 i0 Sheets-Sheet 8 ATTORNEY- March 25, 1952 HARTER ET AL PROCESS OF AND APPARATUS FOR CONTINUOUSLY CASTING METALS 10 Sheets-Sheet 9 Filed Feb. 26 1948 E8 62 mo 68 a: Qw d .TS @256 #625 mzwsou v. .9596 p28 8 M35251 2 22H; QZEEB @255 c 2? -c oowm 00mm 00mm 00mm 005 comm mo INVEN ATTORNEY l. HARTER ET AL March 25, 1952 PROCESS OF AND APPARATUS FOR CONTINUOUSLY CASTING METAL Filed Feb. 26, 1948 10 Shgets-Sheet 10 Q mww 3: m2; 92 Q9 Q3 Q9 Q2 2w 8 3 ON 0 o m 9 MI 55: mm m 3 I H H 8 I m m, mam: 3&3. v l .3 3% 92:96 58 -3 J mic. wzFfi: -3 u mm wwwww 3:5 955E Q u 2 -52 B 6 QZE @255 in H wflwamm www 2 s u m5 m in comm ooom

comm mo INVENTORS fsaac Hatter Y Isaac Harte/j Jr:

ATTORNEY Patented Mar. 25, 1952 PROCESS OF AND APPARATUS FOR CON- TINUOUSLY CASTING METALS Isaac Hatter and Isaac Harter, Jr., Beaver, Pa., and Otis B. Carpenten Barberton, Ohio, as-

signors, by mesne assignments, to The Babcock & Wilcox Company, Jersey City, N. J a corporation of New Jersey Application February 26, 1948, Serial No. 10,956

12 Claims.

. 1 The present invention relates in general to the continuous casting of metal products, and more particularly to a process of and apparatus for the continuous casting of ferrous metals and alloys in semi-finished and/or finished products of indeterminate length and various cross-sections;

The metals industry has long recognized the fact that a continuously cast semi-finished or finished product of acceptable commercial quality,

whose length is limited solely by the amount of molten material available for pouring, offers considerable economic advantages inasmuch as it eliminates the metal casting losses due to cropping and scalping which occur in the production of ingots in individual stationary molds. Processes and apparatus have been in successful commercial use for years for the continuous casting of non-ferrous metals, such as copper and.

delta and of liquid iron. In this state, the alloy has little or no cohesive strength, and is generally referred to as being in the mushy range.

The higher liquidus temperature and considerably lower thermal conductivity of steels in com parison to the freezing point of copper and aluminum affect the casting process. For example, the liquidus temperature of most steels is of the order of 750 F. higher than the freezing point of copper, and 1500 F. higher than that of aluminum. The thermal conductance of most steels is of the order of from 312% that of copper, and from 6-23% that of aluminum. I

- The higher temperature of crystallization and heat content of steel, when in the molten state, necessitates a much greater rate of heat abstracticn from the heat receiving surface of the mold aluminum, having relativel low fusion temperatures and highthermal conductivities. Unwar-' ranted claims have been made for many years in prior patents and publications of the applicability of apparatus and processes successfully developed for the continuous casting of these low fusiontemperature metals to the continuous casting of ferrous and other high melting point alloy products. Yet in spite of thetremendous world production of, and demand for, steel and alloy steel products, for example, these prior apparatus and processes have heretofore failed to result in a single installation in commercial production for the continuous casting of steel and/or alloy steel products.

We believe that the inappllcability of the prior processes and apparatus successfully in use for the continuous casting of aluminum and copper to the continuous casting of steel is primaril due to the substantially different physical characteristics of carbon and alloy steels affecting the casting thereof.

The crystallization (solidification) of pure elementary metals, such as aluminum and copper, occurs at a single sharply defined temperature level, known as the freezing point. The'transition from theliquid to solid states of all initial compounds, including steel, which is an alloy, takes place were temperature range, the limits of which depend on the specific chemical composition of the compound. 0n cooling from the liquid or molten state, a mild steel begins to solidify upon reaching the liquidus temperature and the solidification is completed on reaching the solidus temperature. In the zone between the liquidus and the solidus temperatures, the alloy consists of two phases: solid solution wall in order to maintain the receiving surface temperature at a temperature which will not cause adhesion of the metal being cast to the mold. Furthermore, with the lower thermal conductivity of the steel a wide temperature difference will exist between the surface and the interior of a body of steel being cast dependent upon the rate of heat removal from the surface of the body of steel.

The continuous casting of copper and aluminum does not involve any substantial slag re- 1 "moval problem, whereas the removal of slag presents a major problem in the continuous casting of steel. In the melting of copper and aluminum. the erosive characteristics of the slag and the comparativel low temperatures involved have only a moderate disintegrating effect on the refractories lining the furnace or other receptacles in which these materials are melted or handled. These conditions are much more severe in the manufacture of steel where the development of a slag is a prerequisite for the purification ofthe metal and also in view of the fact that the nonmetallics and iron compounds attack most refractories commonly used for lining receptacles in which steel is handled.

A better understanding of the present invention can be gained from a consideration of the specific problems encountered in the continuous casting of steel. These problems may be divided into two general, but inter-related, subdivisions, i. e., the physical problem ofacontinuously casting steel and the metallurgical'problem of obtaining a commercially acceptable semifinished or finished steel product from such acontinuous casting process.

Referring to the physical aspects of'the problm, the basic apparatus for the continuous cast:

ing of metals includes a fluid cooled mold, open at both ends, which is arranged for the introduction of molten metal into the upper end thereof and the withdrawal of the casting from the lower end of the mold. One of the primary problems of continuous casting is the provision of an adequate cooling efiect on the mold wall to solidify the metal within the mold. This is primarily a heat transfer problem.

One of the principal difficulties encountered in the continuous castingof steel lies in the tendency of the solidified metal to stick to the wall of the mold. This is believed to be the result of improper cooling due to one or more of several factors, such as improper mold material and thickness, inadequate COGlii'lg fluid conditions, oxidizing atmosphere at the molten metal level, the presence of slag in the metal, and rate of casting withdrawal. Sticking to the mold tends to cause rupture of the initially formed thin walled embryo casting.

If the poured metal is too cold or if the mold cooling is too rapid, then shrinkage of the embryo casting from the mold wall takes place rapidly enough to permit additional metal to flow over the frozen rim of the casting and thus cause possible jamming of the casting in the mold with a subsequent break at the point where the casting shell reheats from the fiow of heat from the semi-molten and molten central portion of the casting. If a rupture occurs within the mold, the uppermost section of the embryo casting adheres to the mold while the lower section continues to be withdrawn. Generally, the uppermost section will not free itself sufficiently by shrinkage to permit its withdrawal by the em bryo shell formed by the metal that has flowed outwardly from the center to fill the ruptured gap unless a momentary stoppage is created thus allowing the shell to thicken and subsequently free itself by shrinking in the normal manner. In the event that the operation is not stopped when the sticker occurs, it is likely that the shell formed by the metal that has filled the rupture will be too thinto stand the downward pull of the previously solidified casting and repeated ruptures will take place, until finally a rupture occurs at the bottom end of the mold where the metal is free to run from the casting, thus leaving an empty shell of solidified metal clinging to the interior of the mold.

It is imperative that the ferrostatic head of molten metal be maintained on the embryo casting and as long as this head is maintained an off-center delivery of molten metal to the mold will have no appreciable effect on solidification. The problem of casting is dynamic, with the variables being the rate of withdrawal, rate of pour, degree of metal superheat, and rate of heat transfer from the solidfying metal. The metal will draw away from the mold wall only after initial solidification and formation of the shell. Since this condition is dynamic, it is only harmful when the rate of casting withdrawal is too slow for the rate of solidification and new metal entering the mold flows down between the shell of the embryo casting and the mold wall, wedging the casting to the mold. The superheat temperature of the molten metal as poured and rate of withdrawal of the casting primarily affect the length of the molten core and the porosity of the solidified casting rather than the formation of the shell.

To justify economically the capital investment for a continuous casting apparatus, it is neces sary to attain a relatively high casting rate. This requires a high rate of heat absorption from the molten metal in the casting mold. A high rate of heat absorption from the molten metal within the casting mold and the comparatively low thermal conductivity of ferrous metal combine to permit a quick formation of a solidified shell for the embryo casting. As the shell thickens, the solidified. metal tends to shrink away from the mold wall. The shrinkage of metal from the mold wall reduces the friction therebetween, which is of advantage from the standpoint of some of the physical problems of continuous casting. However, shrinkage of the metal also introduces a heat exchange problem due to the change in heat transfer characteristics between a condition involving heat conduction from the molten metal to the contacting mold wall, and heat transfer across the gap between the surface of the embryo casting and the mold wall.

The low thermal conductivity of steel and the mushy transition stage through which itpasses result in the formation of an elongated V-shaped molten core surrounded by a similarly elongated V-shaped mushy core in the casting which introduce serious metallurgical problems in the continuous casting of ferrous alloys. Also, due to the time-temperature relationship in the formation of the embryo casting, a rapid coolin to form the skin, followed by further rapid cooling to solidify the core, will invariably result in thermal stress cracks, cores, porosity and/or dendritic cracks within the casting. Porosity in the steel casting, exclusive of porosity causedby gas inclusions, is primarily due to the change in specific volume which takes place in the solidification of the molten metal. This is a purely physical characteristic and when porosity occurs in the finished casting it can be attributed to a lack of molten metal feed to the embryo casting to fill the voids formed during the solidification of the metal. Such conditions within the cast product are naturally undesirable and may be alleviated or eliminated by varying casting temperature, rate of pour and rate of heat removal, the latter operation being important both in the mold and after the ingot has been withdrawn therefrom. There is a very complex balance between these variables.

Any sla and impurities carried down intothe mold tend to collect on the periphery of the embryo casting. Since slag has a lower heat conductance than steel, any slag trapped inor on the thin shell of the embryo casting will tend to insulate the covered portion of the casting from the heat removal effect-of the mold wall, so that the shell strength of the casting may be insufil cient to withstand the ferrostatic pressure.im-. posed thereon, and may result in a rupture of the shell. It has also been observed that where the solidification of the adjacent interior portion is delayed, its subsequent solidification. and shrinking sometimes results in the formation of shrinkage cracks and voids in that area.

The principal object of the present invention is to provide a process of and an apparatus for the continuous casting of metal in semi-finished or finished products of a commercially uniform and acceptable quality at a commercially economical rate of production. A further and more specific object is to provide a method and apparatus of the character described capable of effecting the production of semi-finished or finished ferrous and other high melting point-alloy products of indeterminate length which is characterizedby a longitudinal uniformity of metal density and structure. An additional specific object is to provide a process and apparatus of the character described for continuouslyreceiving molten metal poured into one end of an open-ended liquid cooled mold, chilling the molten metal within the mold at a rate of heat transfer sufficient to form an embryo casting, and continuously withdrawing the embryo casting from the opposite open end of the mold with the embryo casting having sufiicient strength to withstand the ferrostatic pressure of its molten and mushy interior without rupture or distortion. A further object is to provide a method of and apparatus for the continuous casting of ferrous and other high melting point alloys wherein the temperature of the molten metal delivered to an open-ended, liquidcooled mold is maintained at a substantially uni form temperature. An additional object is to provide a method and apparatus of the character described wherein the composition of the metal, the rate of molten metal delivery to the mold, the cooling rate of the metal within the mold, and the rate of withdrawal of the casting from the mold are co-ordinated to establish and maintain the production of a substantially uniform high quality casting at a commercially economical rate. A further object is to provide a method and apparatus of the character described in which the casting is subjected to a delayed cooling, soaking or reheating zone to solidify the metal in the casting while maintaining a substantially uniform and minimum temperature gradient transversely of the continuous casting, whereby the structure of the cast product will be substructure throughout its indeterminate length.

In the continuous casting of steel, for example, steel of the desired composition is first melted in accordance with good steel making practice and delivered to a suitable holding and/or pouring ladle. The ladle may be advantageously constructed with metal heating means, operable in case of delay in pouring the molten metal, to

insure that at the time of pouring, the metal temperature will be within an optimum temperature' range, which, while varying with the metal composition, will normally be about 150-200 F.

actions between the slag formed by the reaction of molten metal with one type of refractory 1ming, with a lining of another refractory composi-'-.

tion.

A special stationary casting mold assembly is employed which is constructed and operable to permit the desired high rate of heat absorption from the molten metal and embryo casting formed to be maintained. The casting mold itself is upright and open at both ends, and the delivery rate of molten metal to its upper end is coordinated with the rate of withdrawal of the casting from its lower end to maintain in normal operation a reasonably uniform levelof molten metal within and below the upper end of the mold. The liquid level should not be carried too close to the top of the mold because of both atmospheric and cooling fluid conditions. A substantially uniform ferrostatic head of molten metal is thus maintained on the shell of the embryo casting so as to obviate rupture of the shell. The stream of molten metal delivered is also regulated by adjusting the position of the tun above the liquidus temperature of the metal. As

the refractory linings of the parts in contact with the molten metal are constructed of the same ceramic composition. For example, when the metal is melted in an electric arc furnace lined with a magnesium oxide refractory, as is the customary practice, all the refractory linings thereafter in contact with the molten metal, i. e. the linings for the ladle or ladles and tun dish, should likewise be made of similar magnesium oxide refractories.

The use of similar or compatible refractories tends to avoid chemical re-' dish, to enter the molten pool along the axial center-line of the mold with a minimum of splashing against the mold and so as to avoid turbulence in the molten metal pool in the mold. A quiet pool of metal has been found to promote uniform circumferential cooling in forming the solidified shell of the embryo casting.

The maintenance of a negative meniscus on the upper surface of the molten metal in the mold has been found to be important, if not an essential condition, to successful operation. The character of meniscus formed by the molten metal will depend upon whether a wetting or non-wetting contact exists between the molten metal and the adjacent mold surface. We have observed that the presence of oxides, principally iron oxide,

- and other impurities on the molten metal surface tends to cause wetting of the adjacent mold surface and thus lead to sticking of the casting in the mold, as is evidenced by the formation of a positive meniscus on the molten metal. We have found that complete elimination of oxygen from the mold atmosphere above the molten metal is highly desirable to prevent formation of such oxides. This is accomplished by the continuous introduction of an inert gas, preferably heavier than air and non-soluble in the metal, into the top of the mold to displace any lighter gas, such as air. therefrom and also the introduction of a substance which will consume any oxygen and/or reactive gases that might remain in the mold.

The combined effect produces a substantially oxygen-free atmosphere in the mold space immedi ately above the molten metal level.

' Our process of continuous casting of ferrous and other high melting point alloys is particu larly distinguished by the extremely high rate of mold cooling employed. While the prior art has appreciated that the casting of ferrous alloys would require a somewhat higher mold cooling rate than the casting of copper and aluminum,

\ for example, we have found by extensive experimentation that a ferrous alloy casting cannot be successfully made at an economical casting rate and with commercially acceptable quality, with a rate of heat transfer from the portions of the mold effective in the formation of the embryo casting which is less than several times over the maximum cooling rate heretofore recommended by the prior art for ferrous alloys. This extremely high cooling rate is attained in our process by the introduction of the cooling liquid into the mold-assembly in a manner and in-quantities insuring the entry and maintenance of a solid stream of cooling liquid throughout the mold cooling passage to eliminate cavitation efiects, the fiow of cooling liquid through the passage at a velocity having a calculated Reynolds number for highly turbulent flow conditions, a temperature gradient from the moltenmetal to the cooling liquid such asto minimize the temperature difference between the liquid-contacting liner surface and the cooling liquid, and also a minimum temperature rise in the cooling liquid itself between its points of entry and discharge from the mold passage.

We obtain a metallurgically sound continuous casting by the co-ordination of the described rapid chill to form a shell or skin for the casting of adequate-strength to avoid run outs by the interior molten metal, followed by a controlled-cooling, or in some cases by externally reheating the casting, after it leaves the mold. The best and most uniform grain structure in-a soundsteel casting is obtained by maintaining a minimum temperature gradient between the center of the casting and its periphery throughout its remaining period of solidification. Such conditions require a time and temperature control of the cast product that are entirely different from conditions in a conventional steel casting operation. In the delayed cooling or reheating zone-the solidified shell is reheated by externally supplied heat or by heat exchange with the hotter core. As a result, the temperature gradient from the center to the periphery of the cast product will be minimized and, as the molten and mushy core gives upits heat of fusion to the solidified skin, thecasting will become solidified throughout. During this controlled solidification of the casting, any voids therein created by metal shrinkage will advantageously be afforded sufiicient time to be filled by molten metal from the upwardly adjacent molten metal core. Due to this slow and controlled cooling, the core of the casting is of appreciable length and thus acts in somewhat the same fashion as the hot top ordinarily used in the-steel industry, tending toavoid internal and external stress cracks in'the finished casting.

The descending continuous casting, when below a point where solidification is complete, is periodically cut into a predetermined length by suitable metal cutting mechanism, for subsequent ease of handling and delivery to the point of use.

The various features of novelty which characterize our invention are pointed out with particularity in the claims annexed'to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which we have illustrated and described a preferred embodiment of our invention.

of the drawings:

Fig. 1 is an elevation view of a continuous casting apparatus constructed in accordance with the present invention;

Fig. 2 is an enlarged side view partly in section, of a portion of the apparatus shown in Fla Fig-.3 is an end view taken on the line 3-3 of vFig. 2;

Fig. 4 is an enlarged view of a portion of the apparatus shown inFlg. 3;

Fig. 5 is a side elevation, partly insection. of the tun dish assembly .as viewed from line 55 of Fig. 8;

Fig. 6 is .a cross-section view of the tun dish;

Fig.7 isa plan view of the tun. dish assembly;

Fig. 8 is a front elevation view of the tun dish assembly with certain portions thereof broken away to show details of construction;

Fig. 9 is a section taken on line 99 of Fig. 8;

Fig. 10 is an enlarged sectional elevation of another portion of the apparatus shown inFig. 1;

Fig. 11 is a further enlarged sectional elevation of part of the apparatus shown in Fig. 1.0;

Fig. 12 is a plan view of the apparatus shown in Fig. 10;

Fig. 13 is an enlarged plan view, .partly in section, of the casting cutting apparatus;

Fig; 14 is a vertical section taken on the line |4-l4 of Fig. 13;

Fig. 15 is a horizontal section taken on the line |5l5 of Fig. 14;

Fig. 16 isan enlarged elevation of the severed casting handling apparatus shown in Fig. 1;

Fig. '17 is an elevation of the dummy rod used in the ,continuous casting operation;

Figs. 18 andlQ .are operations charts of typical casting runs with the apparatus shownin Figs. 1-17.

While various features of our improved process and apparatus are adapted for use in the continuous casting of both low and high melting point metals and alloys, our process and apparatus described herein are particularly designed and especially useful for the continuous casting of carbon and alloy steels as well as nickel and high melting point alloys.

In the continuous casting apparatus shown in the drawings, molten steel or otherierrous metal or alloy is introduced at one end of the apparatus and semi-finished products ready for finalshaping and finishing are delivered from the opposite end. The assembly of the apparatus is shown generally in Fig. 1, while the details of the parts are shown in Figs. 2-17. As shown in Fig. 1, molten steel is transported to the apparatus by a transfer ladle [0 from a melting furnace (not shown) and bottom poured to a suitable holding and pouring ladle l I which is constructed and operated to maintain the molten metal therein at a selected temperature, in this case by induction heating. The ladle I I is arranged 'for lip pouring with a regulating mechanism designed to effect a continuous selected .pour rate into an .adjustably positioned tun dish [8 which discharges the molten metal into the upper end of and along the axial center of an associated casting :mold

assembly [2. The molten metal is rapidly chilled in the mold assembly 12 to form the shell or skin of an embryo casting and solidification of the casting completed in a subsequent delayed cooling or soaking section 63, the casting beingcontinuously withdrawn therefrom as a continuous casting [3 at a controlled rate by a set of. powerdriven pinch and/ or withdrawal rolls M, with the continuous casting thereafter passing to the handling portion [5 of the apparatus where the casting I3 is out into predetermined lengths and each length as cut delivered to a horizontalconveyor for transportation to a point of use or storage (not shown).

The pouring ladle H and its operatingmechanisfn shown in Figs. 2, 3 and 4 is disclosed and claimed in a co-pending application of I. Harter, Jr. and S. 0. Evans, Serial No. 746,810 filed May 8, 1947, now Patent No. .2,52.0,598,.lssued August ja cent the upper end of the coil 20. In order to control accurately the delivery point of the stream of molten metal into the tun dish 3 from the lip 24 of the ladle, the ladle is tiltable about a horizontal axis X-X laterally of and movable relative to the moldassembly [2. The ladle is mounted on an L shaped frame 25 having trunnions 26 engaging trunnion bearings 21 on pedestals 3B. As

shown in Fig. 3, the lower edge of the lip 24 preferably lies on the axis X-X. The trunnion bearings 21 are slidable horizontally on guides 3| on the pedestals 30, the lateral position of both bearings being simultaneously regulated by screws 32 operated by a pair of interlocked reversing type gear motors (not shown) The tilting movement of the frame and ladle is effected through a cable 3-3" attached to a cable yoke 34 on the frame 25.

The cable. 33 is passed through a pair of conventional differential chain blocks 35 and is wrapped about/a grooved drum 36 rotated by a reversible motor driven gear drive. The uppermost block 35 is supported from the supporting framework for the drum 36 and its drive, so that the frame and ladle can be rotated through an angle of approximately 90. about the axis XX.

The electrical and cooling water connections to the ladle coil 20 are flexible to permit rotation of the ladle about axis X-X. The flexible electric cables 40 are alternately attached to water-cooled pipes 4i leading to the coil 20 to .minimize electrical loss and reactance. From the pipes 4| the cables 40 pass over a grooved drum 42, mounted in the .frame 25, and over a grooved drum 43 on the building frame-work. The cables '40 are then looped. downwardly around a grooved drum 44 which acts as a counterweight to maintain proper cab'le'alignment. The cables 40 lead to the electrical -control'and frequency generating equipment located at a lower level and indicated generally at 45 in Fig. 1. The flexible water connectionsto thepipes 4| are arranged so that tiltin'g'of the ladle will not interfere with the flow of "cooling water to the coil.

Thus by regulation of the horizontal position of the trunnion axis X-X relative to the mold l2 and the angularity of the ladle longitudinal axis relative to the vertical, the pouring rate of metal from the ladle can be regulated and the point of delivery of that metal to the tun dish l '8can be controlled; Likewise, the temperature of the metal within the ladle and therefore the temperattire of the metal delivered to the mold, can be readily maintainedWithin optimum limits for most advantageous easting results. The three variables commonly resent in the delivery of molten 'metal to a co uous casting molcLname- 1 y; metal. temperature, pour rate, and position of metaldeliveryinto. the tun dish-should be mainshown in Figs. to 9,'are disclosed and claimed in ajco pending application of Ratcliife et 10 at, Serial No. 2,114, filed Jan. 13, 1948, now Patent No. 2,571,033, issued October 9, 1951, the tun dish being adjustable to receive molten metal from the ladle H and to deliver that metal in a continuous stream to the axial center of the mold assembly l2 at the normal molten metal level therein. In order to absorb the impact of the falling stream from the ladle and to return any entrapped slag to the surface and at the same time constrain and direct the turbulence caused by the falling stream, the tun dish consists of an open top refractory lined rectangular box divided into an inlet chamber [8 and a smaller outlet chamber I8 by a transverse vertical refractory baffie or partition I9 located approximately one-third of the length from the discharge end. A transverse inclined refractory baflie section 19 is located in the inlet chamber and extends upwards at an angle of approximately 20-30, with its lower and forward end merging into the vertical baffle l9. Holes 28 in the bottom of the vertical bafile below its juncture with the inclined baffle form separate passages through which the molten metal can flow from the inlet to the outlet chamber. A V-notch refractory weir 29 is formed in the end wall of the tun dish for the discharge of the molten metal. In operation, the tun dish is preheated to a high temperature and normally tilted forwardly about 15 and the tun dish positioned so that the stream of molten metal from the ladle li falls into the inlet chamber and strikes the vertical bafile l9 below the normal molten metal level in the chamber at such an angle that the stream continues todescend until it strikes the inclined baflle l9, which deflects the metal-entrapped slag to the surface, from which it can be removed. The slag-free metal then flows over the inclined baffle and downwardly through the passages 28 in the vertical bafiie to the outlet chamber I8 from which it flows approximately horizontally through the V-notch weir 29.

The tun dish is removably mounted in open trunnion bearings 31 'adjustably supported on a horizontally swinging arm 38 which permits the tun dish to be swung away from the vicinity of the mold for ease in handling. While the tun dish is on the arm and in operation it can be tilted in a vertical plane about an axis located in line with the crest of the weir 29, turned in a horizontal plane about a point directly under the weir, and moved horizontally along its short axis. These motions are primarily for the purpose of correcting any misalignment of the metal stream which may be caused by frozen slag or metal on theweir and thus enable the operator to more accurately direct the stream into the center of the molten pool in the mold. I The tilting of the tun dish is effected by a screw crank 49 contacting with a depending arm 49 secured on one of the tun dish trunnions. Angular movement of the tun dish. about a vertical axis is effected by mounting the tun dish trunnion bearings 31 on a separate plate 58 having a pivotal connection 58 with an extensible section 38 of the arm 38 and a screw crank 58? removably mounted on the outer end of the plate engaging a pivoted nut 58 on the extensible arm section 38, so that operation of the crank willcause the plate 58 to move angularly about the vertical axis of the pivotal connection 58. Lateral movement of the tun dish is effected by an arcuate slide 5!} engaging a fixed arcuate flange 58 on the Yoppositeq-end of the plate 58.

to". the .mold assembly l2.

.and 5, the tun dish weir 29 is close. to the mold .assemblyto minimizeuoxidation of the discharging molten. metal and turbulence of ."the molten metal iirthe mold.

The-slide 59 carries a-laterally projectingbolt 59 on which is In operation the tun dish .thus serves as a Qslag. barrier which tends to prevent the inclusionof extraneous matter in the metal deliv- ,.ered to themold. Although the molten metal .delivered-to the ladle II .is essentially .fclean, .anyinduction heating thereintends to agitate .the metal and frequently metallic oxides or other impurities will accumulate on the surface vof, the metal which are advantageously caught and removed in the tun dish before .delivery As shown in Figsr2 ",The desired extremelyhigh rate of moldv cool- ,ing employed is obtained.byutilizationof .the .fact .that the rate of heat .transfer fromfl'the .moldwall will vary as a .direct function of the velocitybf the .coolingliquid,provided no cavi- .tational. effect orlaminar flow is present'in the cooling liquid passage. .fornthis purpose, shown in detailv in'Figs. 10,111 .;and..12,..is arranged .to .removeheat from the .moltenmetal delivered to its upper. end, and to continuously develop an embryo castingfthere- .in-..whi'ch .is continuously withdrawn from its 1 lower -.end .as hereinafter described. While'in the..mold assembly, lthemoltenmetal and the embryocastingi are in contact with or adjacent vtottheinnersurface of awater cooledyertically elongated relatively thin walled metallic molding tube or mold liner 46 which'is vopenat its upper andlower ends and o'f'the desiredcast- The mold assembly [2 ing ,crossesection, in the present embodiment .one of circular horizontal cross-section. LThe .upperiopen end of'the tube is supportedin a '.top -jplate '4], wherebythe tube is pendantly supported from the fixed'level ofthe plate and is. freetoexpandaxially therefrom. The .plate mold liner "46, and is arranged to confine a flow of cooling liquid against the surface .of the mold "Jliner substantially throughoutits length. The

skirt isalso pendantly supportedadjacent its upiperjendlby attachment Within the central. aperture of .the plate 55. The .upper endiportion-of "the skirt 52 extends above the level ofthe support plate .55, with itsiupper edge fittingiinto a corresponding recess in a surrounding. sleeve 60,

secured on the upper side of plate 5 5,.and'defining a discharge weir from the chamber 56. A relativelynarrow annular open-fended space or water fpassage'53 of uniform width is thus provi'ded'be- "tween the liner 46 and skirt- 52.

"A plurality ofcoolingwaterinlets51-open to thechamb'er 56 at 'luniform circumferentially "spaced'positions;and an annular perforated dis- 7 *tributionjplate 5 lis interposed between'the' inlets andthewaterpassage 53. 'The'upper'end or weir section of thesleeve Glisshaped to 'form 'an an- .ti-cavitation entrance nozzle to the waterf'passage 53, the upper'end of thesleeve"being'rourided and its inner wall cut away to converge at an angle a of approximately 20l'to' a diameter corresponding to the inner .diameterof the" skirt-12.

The lower end oftheskirt'52 is spac'ed from the lowerfend of'the liner 46,both"the" lin'er "and the skirt being unrestrained-"relative to :0ne another at positions below plate 55," so that each may adjust itself in accordance with the-ftemperature and loading imposediby"the=fenclosed metal or'the cooling liquid. "The length. of the mold. liner 46 will depend upon-various factors,

such .as the composition of theim'etal, casting cross-section and the desired: rate of withdrawal of the casting. The mold liner'illustrat'ed when used. for casting 6" rounds was made 108" long.

.In. such a mold assembly thera'diaLjthickness"oi the'wat'erzpassage'53 isiapproximately inch.

high rates. of heat; transfer fromthe'castmetal to the water are involved, ithez wall 'thicknessof the mold liner 46 is advantageously low and where the liner has been made.ofbrassathicmess"of-.

men has been utilized. 'W'herefthe moldlin'er' is made of other material; suchiasunild' steel, stainless-steel or-copper, consideration ofithesomewhat difierent'heat conductivity characteristics will of course be involv'e'd irrthe' determination o! the relateddimensions .iof i the i'heat} coriductive mold liner.

The location of the convergingentrance-fibetween the upper endof'.sleeve60.iand the outside of the" liner 46 so. as to receive aa'cooling water supply from the upper annular portion 'of"' the chamber 56 above the perforated gplate' i I f insures a uniform solid streamofwater intothe passage 53'throughout its circumference. "Imadjdition, the gradually converging entranceelso provides for a gradual acceleration ofthe water are so selected that, withftherate of: circulation and temperature of the water discharged-Wherethrough, a calculatediReynolds' nurnber will:result which will insure;highly'lturbulentfiow conditionsrthrough the passage.

The lower en'dof the mold 'liner46jis [provided with .a frusto-conical water deflecting shield-T50 below the skirt 52 and which is arranged 3 to' -idefiect cooling water. away from? the embryooasting as it emerges from anannular opening'fflii fiat thelower end-of the-.liner 46. The/arrangement of the parts .described:cooperateitoiorm ammcooledportion of the :mold assembly l2 wherein a high rate of;heat.:.excha elbetween thetmolten top and ime icooli'ng maintained to solidify an outer' skin' on the embryo castingwhich-wiH thicken -as the*casting is "withdrawn "downwardly as hereinafter described.

upper end positioned intermediate the Iengthr'of the mold liner 46 and with its lowerend'en'ga'ged by the-pinch rolls l4. The dummy I64 'is "construct ed in' a series or short sections 1651' for .convenience in handlingywith adjacent 'sectionsfhld together by means-of pins I66 so that the dummy may be readily assembled and disassembled.

After molten metal has been delivered to the pouring ladle II and the metal has been heated to the desired pouring temperature therein, cooling water is circulated through the mold I2 and molten metal is delivered to the mold cavity formed in the liner 46 by the dummy I64. When the molten metal level in the mold liner 46 has reached a-predetermined point adjacent its upper end, the pinch rolls I4 are started to withdraw the dummy I64 at a uniform selected-rate coordinated-with the casting variables to form a metallurgically sound casting. The dummy extends from the rolls I4 to an intermediate position within the mold liner 46, and as each successive section I65 of the dummy projects below the rolls-I4, the pin I66 is withdrawn and the section removed for future use. A head I61 on the upper end of the dummy I64 is provided with a cap screw I68 threaded into the upper end thereof. -The lower end of the continuous casting I3 solidifies around and. grips the upwardly extendingshank and head of the cap .screw I68, whereby the initially formed casting I3 can be withdrawn from the mold by the pinch rolls I4 acting on the dummy I64.

Liquid or gaseous materials are introduced into the upper portion of the mold, above the level of -molten metal therein, to provide a non-oxidizing atmosphere above the molten metal. Such liquid materials are largely gasifiecl by the high temperature conditions within the mold, and the primary effect on the gas will be to provide a non-oxidizing atmosphere for the molten metal in the upper end of the mold. Tubes for introducing liquid and gaseous materials into the mold are shown in Figs. 10, 11 and 12 as arranged in circumferentially spaced pairs about the upper end ofithe mold assembly I2. One tube 11a in each pair is connected with a positive displacement flow control mechanism (not shown) whereby a liquid, such as castor oil, may be delivered to the mold, while the other tube 11b is connected with a source of an inert gas (not shown), .such as argon. Argon, being heavier than air will collect in the upper end of the mold above the surface of the molten metal therein, so that oxygen-containing, reactive or metal soluble gases will be displaced and the moltenmetal pool and the entering stream of metal will be protected against oxidization thereof. The exact function of the castor oil in the continuous casting process is not completely understood. Its use seems to be advantageous under some casting conditions, particularly during the initial casting .period. By observation, it is believed that the castor oil is vaporized after'entering the mold and at least partially decomposed in the vicinity of the meniscus of the metal within the mold. The hydrogen released in the deupper end of the mold I2 through the pipe con- 'nections 51.

With the described construction of the entrance section of the passage 53, the water entering the chamber 56 will flow down wardly through the annular passageway 53 in a unifOrm solid stream. In order to obtain the necessary rate of heat transfer to successfully continuously cast ferrous alloys at commercial lineal speeds, it is believed to be essential that a large amount of cooling water be passed through the annular passageway 53. The amount will vary with the casting cross-sectional area and shape and the speed of withdrawal maintained, butin general should be such that the average rise in cooling water temperatures through the mold assembly will be less than 12 F. The maximum cooling rate we have noted in the prior art for ferrous alloys is 30-35 gallons per minute at a head pressure of 75-150 p. s. i. for 6" steel rounds (Patent No. 2,079,644). We have found it advantageous, if not essential, to use a cooling water flow of 350-400 gallons per minute at an entering .water main temperature and a head pressure of 75-100 p. s. i. for continuously casting 6" steel rounds in a mold assembly similar to that illustrated herein. With such cooling water flow rates through the water passage 53, the water velocity therein will be from 43-50 feet per second. Thus, allowing for the usual manufacturing tolerances for the dimensions of the mold liner and skirt, the water flow velocity should be at least 40 feet per second. Consequently it is an essential part of our ferrous alloy casting process that the amount of cooling water supplied should be at least several times over the maximum amount heretofore recommended by the prior art for such casting. A high ratio of cooling water supplied relative to pounds of metal cast per minute thus results. We have found that at low flows of cooling water a falling stream can burn through the side of the mold when the stream becomes deflected while entering the mold cavity.

Due to the relatively restricted cross-sectional area of the flow passage 53, the water flow therethrough will be at a high velocity for effective heat transfer thereto from the outer surface of the mold liner 46. For most effective heat transmission between the mold liner and the cooling water the water flow through the passage 53 should be maintained at a velocity having a calculated Reynolds number indicating a highly turbulent flow rather than a laminar flow. Since the annular discharge end of this water passage is unrestricted and the water discharges into an annular area at atmospheric pressure, the pressure of the cooling water is converted substantially from a static pressure to a velocity pressure. The continuity, velocity and direction of the water stream is thus main tained throughout the length and periphery of the passage. This pressure conversion avoids any tendency for the high static pressure of the water to distort the mold liner 46, which would result in an uneven circumferential cooling of the casting within the mold. Any distortion of the mold liner by reason of expansion and contraction with temperature change would have a further destructive effect upon the formation of the casting in that the casing might have a tendency to bind in the mold and with such an interruption in withdrawal continuity the fragile skin of the embryo casting is apt to rupture. Distortion and/or buckling of the mold is avoided in the construction shown since the component parts are free to expand axially of the mold.

Below the lower end of the skirt 52 and shield 50 is a delayed cooling or reheating zone, or temperature equalizing section, 63, definedby a pair of spaced concentric cylindrical sleeves 54 and 65 which are coaxial with respect to and spaced from the embryo casting formed in the upwardly adjacent mold. The sleeves are constructed in a. variable number of longitudinal sections and the annular space between the sleeves is filled with a temperature resistant heat insulating material 66 maintained in position by upper and lower annular plates 61 and respectively. Cooling water discharging through the annular opening 73 is deflected outwardly by the shield 50 and a frusto-conical plate I! to pass downwardly between the outer sleeve 65 and a cylindrical sleeve M into a reservoir or tank 15. The tank is annular in horizontal cross-section and is provided with a cylindrical inner wall 150. coaxial with the casting and of thesame internal diameter as that of the sleeve 64. Thus the casting formed in the mold continues to be cooled, but at a substantially reduced rate and without direct contact with any cooling water.

When the continuous casting process has been started, with the rate of molten metal delivery to the mold coordinated with the predetermined rate of withdrawal of the casting, thus maintaining a substantially uniform ferrostatic pressure on the casting, the liquid metal will start to'solidify in a boundary layer or skin along the internal wall of the mold liner 48. In the apparatus shown and with the desired rate of supply of cooling water introduced through the connections 51, the skin will start to form within a fraction of an inch of the meniscus of the molten metal and since the distribution of cooling water is substantially equal circumferentially of the mold, the skin formation will also be substantially uniform throughout its circumference. Almost immediately the solidified skin on the casting will shrink away from the mold wall with an attendant reduction in heat transfer by conduction to the mold wall. We believe that the shrinkage gap between the casting and the wall will gradually increase with an increase in skin thickness until the total heat transfer to the mold liner, by both conduction and radiation, is finally overcome by the heat flow from the molten core of the casting to the skin. When this unbalance of heat transfer occurs the thickness of the skin will gradually be reduced with the inner surface of the solidified metal reaching a mushy or plastic stage. drawn further down through the mold the gradual reheating of the skin form the molten core will be reduced to a point where the heat removal from the skin to the mold will again be the greater and the skin thickness will again gradually increase.

It is also our belief that at the instant of initial crystallization a fine-grain shell forms because it is essentially chill cast. Immediately long thin dendrites form increasing in thickness and length as the temperature of the molten core decreases. If the dendrites do not reach the geometric center of the section by the time the core temperature reaches the solidus, nucleation will increase rapidly and the balance of the molten mass will freeze at one time causing a central pattern of equiaxial crystals. The temperature gradient from the central core to the outer surface may and can cause solid transformations such as occur" in the transition of martensite to bainitein As the casting is v an incomplete water quench of a medium to high carbon steel. There is a range of casting thickness when the cooling rate must be lowered in order to obtain a sound ingot. Our experience has shown that it is advisable to avoid the formation of large quantities of equi-axed crystals.

Ordinarily, the casting variables, such as the metal level in the mold, metal pouring temperature and the mold cooling rate are maintained in a substantially balanced or coordinated condition during the casting process. Any minor change in the casting variables usually occurs in the rate of molten metal delivery to the mold and can be corrected by a corresponding compensation in the rate of casting withdrawal from the mold. A more drastic change in one or more of the casting variables may result in a sticker, necessitating a momentary stoppage of the casting withdrawal mechanism which is immediately followed by a resumption of the casting withdrawal. Such an interruption in the continuity should, of course, be avoided for high quality casting production, but is relatively harmless to the process.

Our understanding of the formation of the embryo casting is shown in Figs. 10 and 11 wherein the thickness of solidified metal forming the skin 80, the mushy metal BI and the molten core 82 of the casting are exaggerated for illustrative purposes. The air gap 83 between the mold liner 46 and the skin is shown in exaggerated dimensions in Fig. 11, while due to the small scale of Fig. 10 the air gap 83 is not illustrated. In Fig. 10 we have illustrated the formation of a continuous casting within the mold as heretofore described. It is, of course, understood that the distances between the various zones shown will Vary with the type of metal cast, the rate of casting withdrawal, and the rate of cooling; however for the production of most low carbon steels, the illustration is considered approximately correct; At the level A the metal adjacent the mold liner 46 becomes mushy or plastic with its thickness gradually increasing to the level B-wherea frozen metal shell or skin 80 starts to form. Between the levels B and C the thickness of both the mushy metal 8 l' and the skin 80 gradually increases, while between levels C and D the-skin 80 gets thicker and then thinner as heretofore described. Between the levels D and E, the thickness of the skin 80 gradually increases until at level E the molten core 82 disappears. Between the levels E and F the area of mushy metal 8| is gradually reduced to the level F where the casting is completely solidified.

The removal of heat from the molten metal in the upper part of the mold liner 46 is accomplished primarily by conduction due to the direct contact of the'metal with the inner surface of the mold liner. This heat transfer rate is extremely high. As the metal contacting with the mold liner solidifies to form. the skin 80 of the embryo casting, the outer surface of the casting will gradually shrink away from the mold liner so that the heat transfer will be across the'gap 83 by radiation from the outer surface of the casting skin to the liner 46.

It will be apparent that the temperature gradient between the axis of the casting and its periphery will be greatest at the upper end of the mold. Upon reaching the lower end of the liner it-the casting will have a substantial skin thickness with an inner annular portion of metal in the mushy stage blending into a molten core 82. It is important at this position to eifect atreatment of the casting tending to equalize the tem- 17 peratures throughout a cross-section of that casting. To accomplish this result the casting is withdrawn through the delayed cooling or temperature equalization zone 63 wherein the sleeve 64 is insulated to substantially eliminate the heat transfer rate between the casting and the cooling water passing between the sleeve and the sleeve 14. Within this zone the molten core 82 of the casting will reheat both the mushy metal 8| and the solid metal portion of the casting and in so giving up its heat the core will gradually become solidified by heat exchange with the skin 80. A sound continuously cast section cannot be made, however, if the molten metal V is excessively long. Therefore, the casting should be embryonic for as short a time as possible.

. The pinch rolls l4 shown in Fig. l are arranged to engage the casting l3 after it passes through the annular sump tank and to control the speed of withdrawal of the casting from the preceding mold section of the apparatus. The rolls are driven at a controlled constant speed by an electric motor 90 through a conventional speed reducer (not shown) or by other means for effecting a controlled constant speed of casting withdrawal. The rolls are grooved to correspond to the contour of the casting and grip the casting under the influence of a spring or hydraulic pres sure sufficient to prevent slippage of the casting.

In the illustrated embodiment of the present invention the apparatus is arranged for the continuous casting of ferrous alloy semi-finished products of circular cross-section. This apparatus is readily adaptable for the production of continuously cast products of other sizes and cross-sectional shapes by corresponding changes in shape of the mold assembly. In addition to the. casting of mild steel and alloy steels, the apparatus is adapted for the casting of other high melting point alloys by corresponding changes in the temperature of the molten metal and its rate of pour, the cooling rate, and the speed of casting withdrawal from the apparatus. It is obvious that with the great variety. of commercial ferrous alloys and metals in use in industry at the present time, the requirements for the casting of a specific composition of metal will require a particular combination of the casting variables peculiar to that metal composition for the successful continuous casting of commercial products. We have continuously cast the more common ferrous alloys such as mild steel, 18-8, -20 and similar alloys successfully in com mercial lengths and quantities in an apparatus similar to the one described herein.

Examples of the time-temperature and other relations during typical continuous casting op,- erations with the described apparatus are illustrated in the charts of Figs. 18 and 19. In the charts, the abscissas represent time, in minutes; the left hand ordinates, temperature of metal in degrees F.; and the right hand ordinates power input to the coil of the ladle H in kilowatts and the continuous casting rate in feet per minute. The molten metal is tapped from an electric melting furnace and delivered to the holding and pouring ladle II. This is represented as a time interval (1-!) on the charts. The time the molten metal is held in the holding ladle to establish the optimum metal pouring temperature, is represented as the period b-c. The pouring period for the continuous casting is represented on the charts as the time 0-11. It will be noted that in the run shown in Fig. 18, the molten metal temperature was maintained within a range of plus or minus 1 0 F. at approximately 2880 F. over a substantial portion of the pouring period. During the last few minutes of the pour the induction heating of the molten metal in the ladle was discontinued but the loss of metal temperature is slight and did not affect thequality of the cast product. The casting was a 4" round of mild carbon steel, 95 in length and its approximate weight 4060 lbs. The withdrawal rate was varied between 2-5 ft./min. In the run illustrated in Fig. 19, the pouring temperature was initially 2820 F. and dropped to 2810 F., and the casting was a 6 round, 25', 5" in length, and its approximate weight 2245 lbs. The casting withdrawal rate was maintained at approximately 1% ft./ min.

As a further example of the operation of the continuous casting apparatus and process in casting a small diameter product, a commercial medium carbon steel having approximately the following composition:

Per cent Carbon .216 Manganese .670 Silicon .310 Phosphorus .016 Sulphur .030

and the remainder substantially all iron, was

' melted in an electric furnace and when tapped had a temperature of about 3100 F. During transportation in the transfer ladle lllthe metal cooled so that upon delivery to the ladle H its temperature had dropped to approximately 2800 to 2850 F. The actualpouring temperature of the metal entering the-mold assembly l2was'in the range of from 2900 to 2950 F., which-is afsatisfac tory temperature for the continuous casting of a metal of this composition. This metal -was continuously cast in a mold of circular crossfsection with an internal diameter of three inches. With this shape and diameter the casting was pierced in the as cast condition, with the necessary reheating. In such a piercing operati0n,-the casting delivered by the continuous casting a'p' paratus was cut into 36 inch lengths for delivery as tube rounds to the piercing mill and tubes were produced of, for example, 2 /2 inch 0. D. by A; in. wall." Mechanical tests of such tubes indicated in tensile tests an ultimate strength of from 72,000 to 80,000 p. s. i.; a yield point of from 48,000 to 53,000 p. s. i.; and anelongation in two inches of from 35.00 to 37.00 per cent. All samples of such tubes successfully passed the standard A. S. T. M. flattening and flaring tests for this analysis.

In the continuous casting process used to produce these tube rounds the mold liner had an internal diameter of three inches with a wall thickness of inch. Although the mold liner material used in this particular operation was formed of common mild steel, similar results were obtained with a mold liner of the same internal diameter, but formed from a brass tube having a inch wall thickness and a silver-plated interior surface. With a withdrawal rate of the casting from the mold liner of approximately 48 inches per minute and a co-ordinated molten metal delivery to the top of the'mold liner, the water delivery rate through the inlets was approximately gal, per minute at a pressure of25 p. s. i; Thisrate of cooling is considered to be lower than is desirable in the commercial practice of the invention. Under these conditions of coolase s 1 1 in in the mold, the temperature of the molten metal delivered to the mold was such as to provide approximately 100 F. superheat to assure continuous and controllable metal flow from the pouring ladle.

We have successfully continuously cast carbon steel, for example, in castings of circular or substantlally circular cross-section with coolin water supplied in the described manner in volumes ranging from 1.00-2.50 gallons per pound of metal poured into the mold.

The continuous casting formed in the mold moves downwardly below the pinch rolls I4 into the cutting and handling section of the apparatus. This portion of the apparatus, shown in Figs. 1 and 13 to 16 inclusive, is disclosed and claimed in a co-pending application of I. Harter, Jr., and G. A. Pugh, Serial No. 20,738, filed April 13, 1948, now Patent No. 2,582,329 issued January 1, 1952, and includes vertically movable casting cutting provisions, a vertically movable and tilting cradle anda horizontally disposed conveyor. The descending casting moves downwardly into the cradle 9| until its lower end approaches a shelf 98-at the lower end of the cradle and as the downward movement continues is out to a predetermined length. The shelf is adjustable longitudinally of the cradle to correspond with the length of casting severed. The severed casting 93 drops onto the shelf and the cradle is lowered to a horizontal position from which the casting is removed by the conveyor 94. As soon as the severed casting is removed, the cradle i returned to its upright position to receive the succeeding section of; the continuous casting, with the handling process. repeated to periodically deliver severed casting lengths to the conveyor 94.

The casting cutting provisions includes a gas cutting torch 92 of the oxy-acetylene type which i mounted on a carriage 95 which is arranged for vertical movements within predetermined limits between the pin-ch rolls I4 and the cradle 3|. As shown in Figs. 13, 14 and 15, the carriage 95 is arranged for vertical movement guided by wheels 93 on spaced channel irons 91. The upper portion of the carriage has a pair of pivoted jaws I operated by a double-acting power cylinder I03 through a linkage I02 and common pivot pin I-0-I to grip the continuous casting I3 so that the carriage and the torch will move downwardly with the casting. When the casting has been cut to a predetermined length, the jaws gripping the casting are released and the carriage returned to its: upper position to repeat the cutting operation. A plate I04 having two spaced depending flanges I embracing the body of the torch 92 is supported by a pair of spaced pivots I00, each of which includes a rotatable pin I01 secured to the plate I04 and having a clevis I I0 at its upper end. The clevis is fitted with a bolt III extending through a horizontal slot in an arm II2 which in turn forms the lower end of a second rotatable pin I-I3 mounted upon the carriage 95. A worm I I4 in bearings I I5 slideably mounted in the frame of the carriage 95 is arranged to engage a correspondingly threaded sleeve Il6 attached to the plate I04 and is turned by a handwheel II'I. Thus, the handwheel regulates the movement of the torch 92- whereby the torch flame may be moved in a horizontal plane to traverse the casting I3.

The'cradle SI of the handling portion I5 of the continuous casting apparatus is shown in Figs. 1' and 16. In Fig. 16 the cradle is shown with a severed casting 93 supported therein in an upright position (shown in solid lines) immediately after the casting has been severed by the torch 92; in an'intermediate position (shown in dotdash lines) and in a horizontal position (shown in dotted lines) immediately prior to the removal therefrom of the severed casting by the conveyor 94. The cradle 9| is formed by a pair of channel members arranged back to back to form opposite sides thereof and spaced apart by a set of longitudinally spaced transverse channels extending across the bottom I23 of the cradle. The spaced transverse channels provide openings therebetween matching the rolls of the conveyor 94 when the cradle is in its horizontal position. The top side i24 of the cradle i open whereby the cradle may be returned to its upright position after delivering one severed casting, without interfering with the withdrawal of the succeeding section of the continuous casting IS.

The cradle BI is guided in its movement between a vertical and horizontal position by a pair of flanged wheels I 25 mounted on the bottom I23 at a location near one end, and by a pair of flanged wheels I27- mounted on the top side I24 at the opposite end of the cradle. The movement of the wheels I25 is confined to a vertical direction by guide rails, but since the gage of those wheels is greater than the width of the cradle, the cradle is free to pivot about the wheel axis in its downward movement. The movement of the wheels I21 is directed by a spaced pair of rails I32 which extend vertically a short distance and are bent in a short radius 90 bend to extend horizontally a distance substantially equal to the longitudinal distance between the axis of wheels I25 and I27.

The severed casting 03 and its supporting cradle 9I are lowered from the upright position by an electrically-driven drum hoist I33 equipped with dynamic braking and connected to the cradle by a pair of cables I34. The cables pass over a pair of sheaves I35 rotatable on the structural framework.supporting the continuous casting apparatus.

After the continuous casting has been severed by the torch 92, the downward movement of the cradle is immediately initiated by starting the motor-driven drum hoist I33. The severed casting 93 is forced toward the bottom I23 of the eradle and held in that position until the outward swing of the upper end of the cradle, as determined by the guide wheels I25 and I21, has progressed to a point whereby the Weight of the casting will hold it in position against the bottom of the cradle. This is accomplished by a power piston I36 supported on the framework of the continuous casting apparatus which forces the severed casting toward the bottom I23 to rest. against the transverse channels. The action of the piston is controlled by limit switches (not shown) allowing it to push only when the cradle is near its vertical position.

The conveyor 94 includes a series of circumferentially grooved motor-driven rollers I42, with the individual rollers spaced to match corresponding openings in the bottom I23 of the cradle 9i. Due to the necessity for speed in lowering the cradle, discharging the severed casting and returning the cradle into position for a subsequent section of casting, the lowering mechanism is provided with a shock absorbing device I43 positioned between the rollers I42 of the conveyor 94 adjacent one end of the cradle when it is in its horizontal position.

The shock absorbing device includes a pneumatically operated arm which contacts a projec-

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