US2956320A

US2956320A - Casting of metal

Info

Publication number: US2956320A
Application number: US555923A
Authority: US
Inventors: Pulsifer Verne
Original assignee: Olin Corp
Current assignee: Olin Corp
Priority date: 1955-12-28
Filing date: 1955-12-28
Publication date: 1960-10-18
Anticipated expiration: 1977-10-18

Description

Oct. 18, 1960 v. PULSIFER CASTING OF ma;

2 Sheets-S beet 1 Filed Dec. 28, 1955 2 Sheets-Sheei 2 v. PULSIFER CASTING 0F METAL FIG. 5.

INVENTOR. Msmze fl/LS/Fifi Oct. 18, 1960 Filed Dec. 28, 1955 United States Patent CASTING OF METAL Verne Pulsifer, La Grange, 111., assignor to Olin Mathieson Chemical Corporation, East Alton, 111., a corporation of Virginia Filed Dec. 28, 1955, Ser. No. 555,923

Claims. (Cl. 22-574 This invention relates to theart of casting of metals and more particularly to an improved apparatus and method for continuously casting a slab of metal in the cross sectional shape approaching that of strip or sheet metal. A typical slab may have cross sectional dimensions in the neighborhood from around 4" x /2" up to around 30 x /2 for example.

Heretofore, the method of continuously casting metals has met with a substantial degree of success only in casting of ingots of relatively great thickness. For this reason continuously cast circular ingots and rods or nearly square billets of relatively heavy sections are more common than rectangular sections having a width far in excess of the thickness. But it has long been recognized that it would be desirable to continuously cast a flat slab suitable for further processing to commercial sheet metal by just a few additional finish operations instead of the rather extensive rolling reductions, both hot and cold, and annealing steps required to bring a heavy slab or bloom down to the shape and gauge of the wrought strip or sheet metal product desired.

Attempts have been made to directly cast thin slabs of metal by continuously pouring molten metal between a pair of cooled rolls, e.g. U.S. 49,053, issued to Bessemer, and US. 382,321, issued to Norton et al., or upon the surface of a casting drum, e.g. US. 1,531,747, and US. 1,611,911, issued to Hazelett, or between cooperating drum and belt, e.g. U.S. 359,348, issued to Daniels, and even between traveling belts, e.g. US. 594,- 583 issued to Wood. But metal produced with the methods and devices of the type represented by this and other prior art and known improvements thereon has been inferior and commercially unacceptable except for a few low melting metals, notably lead and zinc. A metal such as cartridge brass or aluminum, for example, produced on apparatus of this type is found to be entirely too porous in internal structure and is characterized by a very poor surface having many cold shuts. These surface irregularities may be attributed largely to irregularities and disturbances in movement of the molten metal as it approaches the mold wall.

Therefore, one object of this invention i to provide a continuous casting apparatus and process free from the difficulties and disadvantages encountered with prior devices and novel methods of producing a comparatively thin continuous casting of metal slab.

Another object is the obtainment in continuous casting of substantial constancy of thermal conditions during the whole of the operation and of regularity of the progress of solidification by having as great and constant as possible a portion of the final cooling affected through the cross section of the ingot itself, with a thermalgradient approaching the horizontal, rather than through the lateral surface of the ingot. Thus internal shrinkage and radial cracking are avoided to a considerable degree.

Another object is to provide a new and improved apparatus for economically and efiiciently casting continuice ous lengths of relatively thin metal metal strip of satisfactory soundness, surface quality and gauge.

Another object is the provision of new and superior means for the substantial elimination of mechanical forces and influences which disturb and impair the proper solidification of the molten metal in continuous casting apparatus of the type described.

A still further object is to provide a new and improved control of the molten metal solidification in continuous casting apparatus of the type described.

Other objects and advantages of the invention will be apparent from the following description and the accompanying drawing in which:

Fig. l is an elevational view in cross section of a preferred embodiment of this invention;

' Fig. 2 is a view taken on IIII of Figure 1; and

Fig. 3 is a cross sectional'plan view taken on line III-III of Figure l. v

In accordance with this invention the foregoing objects are accomplished by the provision of novel apparatus having a combination of coacting features together adapted for improved continuous casting of a length of metal slab of a width far in excess of its thickness as will hereinafter more fully appear. The casting apparatus and process of this invention is characterized by an improved introduction of the metal and by an improved control of the solidification process.

One feature of the invention provides a metal shaping member in which substantially no relative motion occurs between the solidifying metal and the mold or die side walls defining the metal congelation regions of the apparatus. This is accomplished by forming the side walls of unidirectionally traveling surfaces of continuous, spaced apart metal belts or the like which support the molten metal during solidification and also by a particular structural arrangement of molten metal feed which prevents premature contact between the metal and the belts. This eliminates forces that might otherwise occur between the solidifying metal and the walls of the mold. By continuing the occurrence of metal solidification in the casting apparatus of this invention between traveling surfaces of adequate length there is avoided change of metal shape during solidificaton other than the normal contraction which always follows cooling of the metal. Cracks perpendicular to the longitudinal axis of the ingot are virtually avoided by substantially complete elimination of the restraint imposed by the mold.

Another feature relates to the capacity of the aforementioned particular structural arrangement of means for charging molten metal to the region of solidification not only without premature contact but also in a quiescent state and without exposure to other than a protective atmosphere. By this means there is avoided undesired heat loss prior to the point of solidfication. To accomplish this the molten metal is introduced at the proper temperature from a relatively shallow pool under sutficient hydrostatic pressure into a region of confinement having a configuration substantially identical with and in collimation with the cross-section defined by the traveling side walls. This region is positioned to affect the metal immediately prior to entry of the molten metal into the metal shaping portion of the apparatus between the traveling side walls. Thus, rearrangement of the metal volume and the resulting disturbing flow of metal is substantially eliminated at the point of solidification. All disturbance of the metal both immediately prior to as well as during solidification is avoided in the casting apparatus herein described.

Another feature .of this invention relates to interposition of a continuous coating or layer of mold dressing medium of a desired and adjustable thickness and/or composition between the moving metal and the mold surfaces traveling in unison with the metal. The introduction of this medium has a number of functions, but the chief function is the control of the degree of heat transmission through the metal belts forming the mold side walls and regulation of the cooling rate for the casting process. Another is the provision of a reducing material in the mold about the metal as protection against oxidation. The dressing medium also functions as a seal between stationary and moving parts of the apparatus but not as a lubricant for the cast metal. required between the metal being cast and any part of the apparatus. A high degree of control of'the casting process is obtained by the regulation of the thickness of this mold coating material functionng chiefly as an agency for controlling the heat transmission to the sidewalls. Furthermore, by means of this feature of the invention it is possible to not only adjust the mode of metal crystallization and to influence the metal structure forming between the fiat faces of the slab but also to adjust the gauge of the slab within certain limits and from edge to edge. The latter prevents wedge shaped castings which are not desired in the rolling mill.

Cooling of the metal to solidification occurs chiefly through transmission of the heat by way of the solidified section of the casting which is subject to direct fluid cooling. Abstraction of heat longitudinally with respect to the molten metal at the point of solidification through the previously solidified cast metal is the essential means of cooling as compared to the heat lost laterally by way of the dressing media surrounding the metal and the metal belts forming the side walls of the die section of the apparatus. Ordinarily no other attempt is made to cool the rolls, belts or other parts of the apparatus at points at which molten metal is to be found in contact with the casting apparatus, except such cooling of the belts as is inherent to the device shown and described. However, the plastic dressing tends at first to have a relatively brief lateral cooling effect on the metal after which it acts as an insulator. This initial effect may be varied by heating or refrigerating the incoming dressing as desired for certain metals.

In the preferred embodiment described herein and illustrated in the accompanying drawing, the improved strip casting apparatus of this invention comprises a rigid supporting frame 1, carrying a main or discharge mold section 200 for imparting the desired cross sectional shape of the casting and an entry or upper mold section 100 for giving the molten metal a desired preliminary spatial arrangement and for feeding the molten metal to the other section under certain desired conditions. Supported on and journalled in the frame lane a first pair of

face pinch rolls

2 and 3 and a first pair of side pinch rolls 4 and 5, which together with the

face rolls

2 and 3 are the entry rolls. Also rotatably supported on the frame are a second pair of face rolls 7 and 8 and a second pair of side rolls the latter of which are not shown in the drawing but which are related to side rolls 4 and 5 as rolls 7 and 8 are to rolls 2 and 3. Movably supported on these rolls are two

mold face belts

13 and 14 and two

mold side belts

15 and 16. Disposed in the entry side of the bite of the first pairs of rolls but spaced by a predetermined distance, found suitable in practice, from the surfaces of the belts passing over these rolls is a hollow pouring block or tundish 17 adjustably supported on the frame saddle 18 mounted on frame 1. Housed in the saddle 18, in close association with the pouring block 17 and each of the first pairs of orifice defining rolls, are

supply chambers

19, 20, 21 and 22 for feeding a plastic mold dressing material 23 between each of the belts and the pouring block. Also mounted on the frame saddle 18 is any suitable adjustable means for varying at will the opening between surfaces of the

belts

13, 14, 15 and 16 and the block 17 No lubrication is.

and thereby controlling the thickness of dressing mate rial fed therefrom in interposed relationship between each of the traveling mold belts and the metal of the casting.

The sizing pass 26 of mold section 200 is generally defined by the complementary

mold face belts

13 and 14 and the complementary

mold side belts

15 and 16. These at pass 26 support the molten metal in its transition to the solid state without relative motion between the solidifying metal and the surrounding belts and also aid in influencing the heat abstraction desirably. A pass length at least adequate to accomplish the foregoing is selected.

The

belts

13,, 14, 15 and 16 are, carried, about the pair of rolls 2 and 7, pair 3 and 8, pair 4 and 9' and pair 5 and 10 respectively. The rolls are driven in unison in any suitable manner. To assure that all belts move at the same speed together, each group of rolls is interconnected as by bevel gears 6. I

Each belt is preferably a thin continuous band of metal such as stainless steel. The bridging parts of the belts coming from each one of the confronting faces of the first pairs of rolls, and taken up on a corresponding one of the confronting faces of the second pairs of rolls are maintained by any suitable means at sufiicient tension to cause these parts of the belts to travel in straight lines between each of the two respective rolls on which each belt is supported and operated. These straight line portions of the belts adjacent the lateral edges thereof are disposed in a contiguous relationship with respect to each other such that together the belts form the four traveling side walls of a generally rectangular passage.- way or cavity into which the molten metal is teemed directly from the pouring block 17 and it is in this substantially rectangular cavity that the shaping or molding of the casting occurs.

The

mold face belts

13 and 14 which correspond to and confine the wide fiat faces of the strip to be cast, are broad and flat as compared to the relatively narrow

mold side belts

15 and 16.

In order that the side belts may better fit in sealing relationship against the spaced parallel

mold face belts

13 and 14, each of the side belts preferably is provided with a concavity by running the relatively narrow side belts around pairs of concave faced side rolls including rolls 4 and 5 each of which has a face width somewhat less than the width of the flexed mold side belts in order that the edges of the side belts may extend somewhat beyond the side pinch rolls whereby the side belt edges are adapted to be forced into spring pressure contact with the mold face belts. This concave shape of mold side walls gives a desirable convex or rounded edge contour to the casting and tends to reduce severe corner cooling which introduces unequal contraction and may result in splitting of the casting.

Entry mold section is defined by the pouring block 17 of the construction shown and hereinafter more fully described and which is constrained in aligned but spaced relationship with the belts on the entry side of the four roll assembly of first pairs of rolls defining the entry orifice of the sizing pass referred to above.

The tundish or block 17 is made of any suitable refractory material such as Carborundum, and preferably a dense clay graphite mixture or a suitable metal boride, such as zirconium. It consists of (1) an upper part or receptacle for holding a relatively shallow reservoir 31 of molten metal maintained at a constant temperature near the solidus and at a constant level and also of (2) a second or lower part 32 known as the pouring or downspout designed to project in form fitting relationship between the entry faces of the belts as they pass over the entry bite or orifice defining rolls. This spout part of the block 17 has outer concave surfaces complementary to the contour of the roll surfaces and the surfaces of the belts which ride on the rolls and pass in interposed relationship between the lower form fitting part 32 of the block "17 and the orifice defining rolls. This spout 32 encloses a mold entry passageway 33 having surfaces defined by the parallel straight lines tangent to the aforementioned rectangular mold sizing pass 26 defined by the belts as they pass over the first set of rolls. This rectangular passageway serves to lead the molten metal under desired confinement within the block from the reservoir 31 to the zone of congelation between the

belts

13, 14, 15 and 16 not only without exposure to the atmosphere but also without premature lateral cooling and freezing with the concomitant undesirable formation of a curvilinear metal skin that would ordinarily be formed in the absence of mold section 100 and immediately thereafter undergo disruption beyond the roll pass or bite to make a strip having as a consequence an inferior quality. Further the passageway 33 serves to give the molten metal a prelimenary shape like that of the final casting so that subsidence of metal cross flow, counterflow and turbulence may occur in the passageway 33. The spout portion 32 of the block 17 extends as close as possible to the sizing pass 26 defined by the closest approach of the surfaces of the four belts riding the entry rolls at the bite of these rolls. By means of this particular block structure there is prevented the inception of freezing or solidification of the molten metal on the converging faces of the mold face and side belts at the rolls before the metal has reached a point at the aforementioned orifice. The prevention of freezing on the interior walls of an open ended traveling belt type of continuous casting mold prior to movement of the metal to a place in the mold having the desired constancy of shape is an important factor together with the other features of the invention in securing a high quality continuously cast slab of metal.

While the block 17, forced by any suitable mean to ride in juxtaposed relationship adjacent the dressing medium on the moving belts, has been described as feeding metal vertically downward, it is evident that the apparatus may be modified to operate horizontally or even to feed the metal upwardly. The depth of the reservoir 31 is not limited to the radius of the rolls and is made adequate to exert enough pressure to resist gas release and the resultant porosity in the metal.

At the point of transfer of the quiescent molten metal from the passageway 33 in the block 17 to the main mold section 200 between the traveling mold belts, there is fed by extrusion a thin peripheral layer of semi-solid mold dressing medium 23 of controlled anti-oxidant and preferably thermally insulating composition, of suitable plasticity and of controlled thickness between the molten metal and the belts. A suitable medium may consist of one or more of carbon black, graphite, bone ash, magnesium oxide, asbestos, vermiculite, kieselguhr, or diatomaceous silica or porous silica gel sold under the trademark Sil-O-Cel in any suitable vehicle such as kerosene, lard oil, or a silicone. The medium is compounded to give suitable properties and a small but desired amount of inert or at least reducing atmosphere under the various conditions encountered in the casting operation. The dressing applied to the mold face belt 13 may be identical with the dressing applied to the opposing mold face belt 14 but also may be of difierent composition in some cases to facilitate crystallization control in the casting. The dressing applied to the

mold side belts

15 and 16 as a rule should be of a more heat insulating nature than the dressing applied to the face belts 'which may be accomplished in the former by a high content of kieselguhr, bentonite or the like. With appropriate subdivision of each chamber, different dressing may be applied to the same belt. The dressing layers from all supply chambers together form a thin sheath 41 surrounding the periphery of the metal and serves as a conductor of heat of controlled resistivity to the lateral flow of heat from the metal being cast to the bands of metal between which solidification takes place.

The element of control is effectuated chiefly by variation in the thickness of the thin extruded layer 41 of dressing compound carried by the belts. While it is preferred that the thickness of the dressing layer 41 be less than or at most not greatly in excess of about 0.005 of an inch, the thickness is to be varied by the mold operator until there is achieved the desired casting quality and thickness as hereinbefore explained. The thickness of dressing will, of course, vary with the composition of the metal cast, with the composition of the dressing, with the temperatures of the charging metal and cool-ant employed and also with other factors such as variations in the thickness, cross sectional area and speed of the strip of metal 'being cast.

As a further means of controllably varying the heat transmission via the belts and to improve the dressing carrying capacity thereof the belt surface facing the casting cavity may be provided with an adherent film of oxide or phosphate or the like. The same surfaces of the belts may also be initially scratch brushed to an extent insufiicient to increase the heat transmission capacity thereof seriously but sufiicient to aid initial adherence of the dressing medium to the belts. With a suitable dressing a network of scratches in the belt surfaces may provide a replica surface on the casting responsible for more rapid removal of heat by way of the emerging casting.

For varying and holding the spacing of the pouring block 17 from the surfaces of the mold face and side belts and thu for varying the dressing charging opening or gate circumscribing the casting metal at the points. where passageway 33 in mold section 100 terminates and main mold section 200 begins, there is provided on each side any suitable means such as screw-down rods 35, the internally threaded helical gear 36, the equalizer rod 37 with screws 38, the internally threaded helical gear 39 with hand wheel 34, and compression springs 40.

Alternately, there may be provided a number of wedge cams carried by the frame 18 for adjustably supporting the block 17, it being yieldably urged toward the bite of the first pairs of pinch rolls by suitable means such as springs. Such wedge cams would be adapted to coact with corresponding cam following surfaces formed in block 17 as the cams are operated by suitable manually controlled mean such as lead screws. However, it is to be understood that other means equivalent to the screwdown means shown or the cam means referred to may be substituted therefor. In any event such means for one side may be operated either at substantially equal orddifierent rates with respect to the means for the other si e.

Dressing material 23 is carried in arcuately shaped supply chambers having walls extending from the saddle 18. Each chamber has opposing lateral walls contiguous with one of the 'belts and is open on an arcuate side at the belt with which it is associated. Although one chamber is shown for each belt, it will be appreciated that there may be a plurality. As a means for urging the plastic dressing medium from the

supply chambers

19, 20, 21, and 22 into the space between the convex surfaces of the mold belts and the complementary concave surface of the block 17 and for injecting the dressing as a thin sheath on dis belts about the molten metal from the circumscribing orifice at the point where the molten metal leaves passageway 33 in the block 17 and enters the sizing pass 26 and straight walled portion of the traveling belt mold section 290, there is provided in association with each dressing supply chamber a fluid pressure operated ram 50 pivotally supported at one end on the frame 1 and connected at the other end to pistons 51 having suitable arcuate sides to ride the belt and fit the roll surface embracing chambers. This construction is especially advantageous for the belt-over-rolls type of casting machine of this invention.

Congelation of the metal occurs in the moving sheath of dressing material borne by the belts traveling inunison with each other and the metal being cast.

Cooling of the metal to solidification in the final stage of latent heat abstract-ion is accomplished primarily by drastic longitudinal heat transmission through the solidified ingot 42. This is preferably done by means of jets of cooling water issuing from a plurality of nozzles 45 positioned adjacent the delivery end of mold section 200 immediately opposite the belts passing over the second or discharge sets of rolls 7, 8, 9 and 10. High pressure cooling water directed between the emerging casting 42 and the coated belts results in a profuse and turbulent flow of the coolant over the casting surface which is large for a rectangular slab shape case as compared to the volume of the casting, thus effecting a comparatively rapid abstraction of heat therefrom. Furthermore, impinge ment of the high pressure jets of water serves to cleanse both the belts and the ingot of adhering spent dressing material, and to replenish the immersion bath 46 with a stream of cooler liquid replacing the warmed liquid discharged. The resulting longitudinal abstraction of heat is proportioned as needed in the early stages of metal cooling with a variable portion of lateral heat abstraction which rapidly becomes minor as the metal progresses through section 200.

In the device of this invention, collimation of all parts of the molten and solidified metal undergoing casting is achieved as is the avoidance of any disruption of the crystallization process from disturbances caused by bending or vibratory forces, which would be set up by lateral misalignment. This is done by supporting both the entry and the discharge rolls of mold section 200 in the rigid frame 1 and by nesting the pouring block 17, of the particular structure shown and described, in form fitting relationship just ahead of the bite of the entry rolls. By the supporting system here disclosed alignment between

sections

100 and 200 of the casting apparatus is maintained and undesired movement and bending between the solid casting 41 and the molten metal at the zone of congelation in sizing pass 26 is prevented.

The general operation of the casting apparatus and method of this invention should be readily understood in view of the foregoing description, but may be described together briefly as follows: In operation, first of all, molten metal is teemed into block 17 of mold section 100 to maintain the desired level of the reservoir 31 from which liquid metal at a desired temperature is fed to passageway 3-3 of down spout 3-2. Here, the molten metal under hydrostatic pressure arranges itself to the desired spatial shape, and turbulence in the flowing stream has an opportunity to subside. From passage 33 the metal enters the sizing pass 26 between the belts of mold section 2-00 where the metal encounters the refractory dressing material 23 being extruded in a layer 4-1 of desired thickness, composition and temperature for the metal being cast. in this traveling lateral sheath, the heat of themetal is abstracted at first laterally over a small portion of travel of metal, belts and the dressing layer. As the lateral cooling elfect diminishes rapidly, the longitudinal cooling eifect of cooling sprays 4S and coolant bath 46 becomes stronger. At this point in the process, dressing layer 41 operates as a heat insulating sheath. The resultant cooling in ingot 4 2 is manifested by gently curved isotherms approaching the horizontal instead of the deeply curved isotherms which are accompanied by an extremely high gradient especially at the lateral surfaces of many heretofore continuously cast ingots. Thus, while the metal is in sizing pass 26 of mold section 22, an excessively rapid succession of isotherms is avoided. In sizing pass 26 the metal is supported adequately in its transition to the solid state during which it is subjected to no change of shape as occurs on prior casting machine with rolls or drums. Furthermore, there is no relative motion between metal and the mold so that frictional restraint, cold shuts and cracking perpendicular to the ingot axis are avoided.

As the :solid metal .42 with desirable external shape and internal structure emerges from pass 26 substantially all of its surface is subjected tostrong cooling by sprays 45 and quench bath 46. At this point the casting process has progressed sufiiciently so that there is no danger of impairment of the metal by the quenching. At the same time the

belts

13, 14, 15 and 16 of the apparatus are cleaned off in condition for another cycle through

dressing supply chambers

19, 20, 21 and 22. I

The apparatus and process are admirably adapted to automatic control. The speed of the casting, feed of the dressing medium, and both the temperature and impingement of quenching liquid at 45 and 46 may be interlockingly controlled by any suitable sensory control equipment which may be associated with the apparatus described.

From the foregoing description it is obvious that one advantage secured by means of the apparatus and process of the present invention is that the moving metal begins solidifying at points substantially all equally remote from the point at which the molten metal is charged to the mold and solidification proceeds directionally in a controlled manner toward the charging point with a minimum of hindrance by lateral solidification whereby shrinkage voids and serious bridging are virtually eliminated even in the case of alloys having a wide freezing range. Further, by means of the present invention, although an extremely shallow freezing crater is obtained, uncontrolled penetration by the incoming stream of molten metal from the charging point is prevented since the momentum and turbulence of the stream is eliminated and as a consequence the solidifying metal has a minimum of gas carried down into it and washing contact with liquid metal is prevented. Especially this invention is directed to producing ingots reasonably free from surface cracks, segregation, and internal disruptions all of which are known to occur when metal is chill-cast on and subjected to squeezing action between the converging surfaces encountered in prior casting devices of the roll type.

While the invention has been described without reference to any particular metal, any suitable metals such as copper, aluminum, magnesium and steel and their alloys may be continuously cast with advantage by means of the apparatus and process described herein. Although with some modification linked sections may be used in lieu of the belts, endless belts of either solid, stranded or woven construction are preferred because of the smooth surface obtainable on the ingot, the reduction possible in the bulk of the apparatus, as well as the unique suitability of belts to the entire design.

Since other embodiments may occur to those skilled in the art, it is to be understood that various modifications may be made in the invention described without departing from the spirit thereof and that the foregoing is intended to illustrate a preferred embodiment and not to limit the scope of the present invention except as set forth in the appended claims.

What is claimed is:

1. An apparatus for the continuous casting of metal in a rectangular cross sectional shape having a width far in excess of the thickness thereof comprising a rigid frame, at least a pair of associated entry rolls in spaced elongated parallel relationship, a corresponding second pair of discharge rolls in line with said entry rolls but longitudinally spaced therefrom, said rolls being rotatably mounted in fixed spaced relationship with respect to each other on said frame, a pair of short entry rolls together with a pair of short discharge .rolls each pair of which is arranged in spaced parallel relationship with respect to each other and transverse to said arrangement of elongated entry rolls and discharge rolls respectivehhendless belts each mounted to travel between one roll of said first pair and one roll of said second pair of rolls in spaced parallel relationship between the movable confronting portions of said entry and second pair of rolls, said rolls and belts defining a rectangular sizing pass adapted it travel with and shape the metal, means for feeding aaaeaae molten metal to said sizing pass, said means extending into the space between said belts at the confronting portions of said entry rolls and having outer concave surfaces complementary to the contour of the converging part of said rolls and traveling belts and terminating in proximity to the point of minimum spacing between said entry rolls, means for mounting said metal feeding means in spaced relationship with respect to the portion of the belts traveling over the entry rolls, said extending portion of the feed means having a passage for feeding the molten metal in a cross sectional area and shape substantially identical with the cross sectional area and shape of said sizing pass, and means for continuously feeding a layer of dressing medium to said pass and between each of said belts and the metal issuing from said passage.

2. The apparatus of claim 1 having means for applying a high velocity stream of cooling fluid directly to substantially all of the surfaces of the solid metal shape immediately upon its emergence from the sizing pass adjacent the discharge rolls at an angle so as to direct said stream into impingement with the metal at the point of divergence of the belts from said discharge rolls so as to obtain maximum cooling of said casting and said belts.

3. The apparatus of claim 1 wherein the means for mounting the metal feeding means is adjustable so as to vary the thickness of the layer of dressing medium carried on the belts into the sizing pass.

4. The apparatus of claim 2 wherein the means for mounting the metal feeding means is adjustable and wherein the means for applying cooling fluid is also adjustable, whereby deirable proportioning of both lateral and longitudinal heat abstraction is obtained.

5. In apparatus for the continuous casting of metal, a pair of spaced rolls and belts converging over a portion of the surface of said rolls and passing through and beyond the bite of said rolls in spaced parallel relationship to define a sizing pass, means for distribution of molten metal to said sizing pass, said distribution means having outer concave surfaces complementary to the contour of the converging portion of the belts and an internal passage in collimation with said sizing pass and of cross section substantially identical with the cross section of the sizing press, and means for feeding a layer of dressing medium of desired thickness between said opposed surfaces of the belts and the metal being cast in the sizing chamber, said last means comprising an arcuate- 1y shaped dressing supply chamber mounted with an arcuate open side adjacent the surface of each of said belts at its roll, a positioner for spacing said concave surface from said portion of the belt on the roll whereby a dressing feed gate orifice is established between said supply chamber and sizing pass, and a piston for extruding dressing material from said supply chamber from said gate orifice into the sizing pass as layer on each of said traveling belts.

6. Apparatus for the continuous casting of metal in a rectangular shape having a width in excess of the thickness thereof comprising coacting sidewalls completely surrounding an open ended congealing cavity and moving in unison with said metal being cast, said side walls consisting of a pair of relatively broad face belts in relatively closely spaced substantially parallel, opposed relationship and a pair of relatively narrow side belts in relatively remotely spaced substantially parallel opposed relationship, said side belts being concavely shaped with respect to said cavity and having lateral edges maintained in contiguity with the opposed surfaces of said face belts inwardly from the lateral edges of the face belts.

7. The apparatus of claim 6 including means for applying a desired thickness of dressing medium to the interior surfaces of said belts. l

8. The apparatus of claim 7 wherein the means for applying dressing medium consists of a dressing supply chamber having a gate adjacent each belt at the rolls and a piston for extruding the medium through said gate over the belt.

9. The method of continuous casting of metal comprising feeding molten metal into a first mold portion under low hydrostatic pressure of a shallow pool of the metal with a minimum of turbulence to form a confined stream having both a cross sectional and axial shape substantially identical with that of the solidifying metal, for a substantial distance in the axial casting direction whereby the stream is maintained substantially turbulence free, applying a plastic mold dressing medium to the wall of a second mold portion continuous to the first and moving axially to form a peripheral sheath laterally of the metal while adjusting the thickness of said sheath and simultaneously feeding said stream to initially cool and congeal it within said predetermined thickness of sheath traveling in unison with the metal being cast, and thereafter applying a cooling agent to the surface of the ingot substantially immediately upon its emergence from said second portion, thereby abstracting heat from the metal axially at all times during casting and laterally only by initial contact of the metal and sheath at a rate controlled by said dressing.

10. In apparatus for the casting of metal in a continuous length, open-ended metal shaping mean having straight side Walls traveling with the metal being cast, means separate from said shaping means for feeding the molten metal between straight walls directly to said metal shaping means substantially without turbulence and in the final cross sectional shape and with a straight axis identical with that of said metal shaping means for a substantial distance in the direction of casting, means for variably spacing said shaping means and feeding means, and means for interposing through said space a thickness of traveling dressing medium between the side wall of said shaping means and the metal so that said thickness is controlled in correspondence with said spacing, said side walls and dressing medium traveling in unison with the metal being cast.

References Cited in the file of this patent UNITED STATES PATENTS 379,096 Brooke Mar. 6, 1888 441,643 Close Dec. 2, 1890 594,583 Wood Nov. 30, 1897 1,321,658 Mellen Nov. 11, 1919 2,108,753 Low Feb. 15, 1938 2,128,941 Hudson Sept. 6, 1938 2,131,070 Poland Sept. 27, 1938 2,169,893 Crampton et a1 Aug. 15, 1939 2,171,132 Simons Aug. 29, 1939 2,183,010 Coxe Dec. 12, 1939 2,225,373 Goss Dec. 17, 1940 2,242,350 Eldred May 20, 1941 2,348,178 Merle May 2, 1944 12,527,545 Goss Oct. 31, 1950 2,560,639 Giesler et al. July 17, 1951 2,640,235 Hazelett June 2, 1953 2,770,022 Brennan Nov. 13, 1956 2,790,216 Hunter Apr. 30, 1957 FOREIGN PATENTS 703,269 Great Britain Feb. 3, 1954 108,184 Australia Aug. 4, 1939 813,755 Germany Sept. 17, 1951