US3435879A - Continuous casting method - Google Patents

Description

April 1, 1969 J. l. GREENBERGER 3,

CONTINUOUS CASTING METHOD Sheet Original Filed Jan.

P .6 90 mm. g 7 MG 5 L ATTORNEY.

Aptil 1, 1969 J. I. GREENBERGER CONTINUOUS CASTING METHOD Original Filed Jan. 11' 1965 I v a: m wvmwflw W 6% I Mk NIH MN \V I 1 V5 i I I II z I Q I ww w wn \n u m J I I E R 1 Q mN. A q W- w, w w

I ATTORNEY.

Apri 1969 'J. l. GREENBERGER CONTINUOUS CASTING METHOD Sheet 3 Uriginal Filed Jan. 11. 1965 i fllil m a 11ft g k N I... a m HM ww Q h f 1 w w Q Q 3 mm Q G mm ww M/VEA/F'OQ. JOSEPH J. aesavasmm April 1, 1969 J. l. GREENBERGER 3,435,879

CONTINUOUS CASTING METHOD Original Filed Jan. 11. 1965 M/VEA/TOR. JOSEPH J. GA'E/VBEQGfQ 5y ATTORNEY.

United States Patent US. Cl. 164-83 3 Claims ABSTRACT OF THE DISCLOSURE Continuous casting with a vertical oscillating mold and an attached straight secondary cooling device. The strand is bent from vertical to horizontal after leaving the straight secondary cooling device and while still having a molten core.

The present invention relates to the art of continuous casting as employed particularly in the basic ferrous industry. Without intending in any way to limit the invention and only for the purpose of description, the use of the invention in connection with the continuous casting of normal carbon steel billets will be discussed.

This is a division of US. Patent No. 3,370,641 that issued on Feb. 27, 1968, for a Continuous Casting Machine.

While there are various forms of continuous casting machines being presently utilized in the basic steel industry, it is believed only necessary herein to refer to but four, namely, the arrangement of a straight vertical mold and a straight vertical secondary cooling section wherein the cast product is cut to length in the vertical position; the arrangement of a straight vertical mold and a relatively long vertical cooling section, which is followed by a vertical pinch roll-bending station which bends the cast product to discharge in a horizontal direction of travel; the arrangement of a straight vertical mold followed immediately by a curved secondary cooling section; and lastly, the arrangement of a curved mold followed immediately by a curved secondary cooling section. The last two arrangements are sometimes referred to as low level arrangements and possess a number of advantages over the first two. One advantage of the low level arrangement which is suggested by the term itself is the considerable savings realized in reducing the height of the plant, in view of the fact that there is no long straight vertical secondary cooling section. A second advantage has preference to the ease with which the continuous cast product can be handled after leaving the casting machine. In the first arrangement the continuous cast product must be cut into specified product lengths while traveling in the vertical direction after which each cut length is rotated as much as 90 in order to etiect its discharge from the casting machine, after which the rotating mechanism is returned to receive the next length. In the low level arrangement, While the cast product issues from the mold in a relatively vertical direction, it is bent to discharge in essentially the horizontal direction, in which it is conveniently cut into required lengths and discharged from the casting machine without need for rotation or tilting of the product or necessity of repositioning of any tilting equipment. The second arrangement, while it eliminates the tilting equipment, since the cast product is caused to take a horizontal position where it is cut into the required lengths, it still takes up substantially more height than the low level arrangement.

While the employment of either of the low level casting arrangements affords some beneficial advantages, they also impose some serious risks, both with respect to the ,;important considerations, effects and phenomena sur- "ice productivity and soundness of the cast product and in the handling of the cast product, particularly, in the designing of an acceptable dummy bar system.

One of the most serious concerns of the present low level casting machines has reference to certain characteristics thereof that are conducive to metal breakouts and surface defects, which characteristics also detrimentally affect the obtaining of a sound cast product, both from a metallurgical standpoint as well as the quality standpoint. The danger of repeated metal breakouts in the low level casting arrangement can be better realized when it is considered at what point in the casting process the cast product is forced from the vertical into the horizontal direction of travel and also taking cognizance of the fact that the cast product below the mold is being pulled out of the mold by the withdrawal mechanism. In the curved mold arrangement, wherein the curved mold is followed immediately by a curved secondary cooling section having a radius the same as or similar to the curvature of the mold, the thin skinned cast product is subject to bending stresses imposed while the skin of the product is extremely hot and thin and still increasing in thickness. Moreover, these stresses are normally developed above the lowest point of stream penetration of the incoming molten metal. Stream penetration is caused both by the weight and the metallurgical reaction of the molten metal when poured into the mold which under ideal circumstances results in a symmetrical cone-shaped reservoir of molten metal surrounded by thin solidifying outer walls or skin. In certain types of steels, such as rimming steels, great agitation and pressure are developed in the stream zone which has the tendency of washing or eroding away the solidified inner skin and adds considerably to the difliculty being discussed. In fact, for this reason in casting rimming steels, a curved mold arrangement is deemed infeasible since it does not permit a symmetrical development of stream penetration, thus allowing the formation of portions of walls of unequal thickness wherein local portions of one of the walls may be extremely thin. Some of the rounding the stream zone in continuous casting rimming steels are set forth in greater detail in an article entitled The Mechanism of Crystallization of Rimming Steel During Continuous Casting by V. B. Gankin and G. N. Oyks (University Bulletins, Ferrous Metallurgy) No. 1, Moscow, 1963, pp. 34-41, which can be obtained from the US. Department of Commerce, Olfice of Technical Services Joint Publications Research Service, Building T-30, Washington 25, DC.

The casting of wide slabs by the curved mold arrangement has produced additional serious problems. Slabs so cast have been found to take the form of a trapezoid in which the short top side thereof due to internal stresses developed during initial solidification have resulted in serious top surface cracks. The development of a nonrectangular cast product, as Well as the cracking problem, is believed due to the gravitational eiiect wherein the molten metal tends to favor the long bottom side of the cast product, the unequal cooling of the thin pliable walls due to the difference in radii of the two opposite sides and the unequal forming of the thickness of port-ions of the walls due to the non-symmetrical action of the penetration stream.

In the straight mold arrangement followed immediately by a curved secondary cooling section, the condition as to when the bending stresses are applied is also detrimental since bending of the product. takes place when the skin is very hot and thin. In this case also the bending stresses are imposed at a point normally above the lowest point of stream penetration. For use in casting rimming steels, as far as the washing eifect, the straight mold arrangement is somewhat superior to the curved mold artrangement since its walls are straight, thus, since its walls :are straight, thus, permitting a ymmetrical development of the stream penetration and solidification of walls of equal thickness.

Thus, it will be appreciated that in the two prior low level casting plant arrangements the bending stresses are developed at the very area of the cast product which is the most delicate and conductive to breakouts. This points up another serious disadvantage of these arrangements. Since the molds of the arrangements in question pursuant to well-established practice are continuously oscillated (during the casting process, a continuously varying gap exists between the bottom of the mold and the top of the secondary cooling section. Thus, at the very area where, in view of the bending stresses, the Walls of the cast product should be provided with as much support as possible, the prior arrangements allow the products to be unsupported to a great extent.

Not only is it extremely difficult to avoid breakouts in the low level casting arrangements because of bending stresses imposed within the zone of tream penetration as well as varying gap condition, but the danger is enhanced by two other inherent conditions. The first is the hydrostatic pressure effect of the depth of molten me tal tending to force it through the thin walls of cast product. The second i that during the first solidification and contraction phase, wherein the outer skin moves away from the mold walls in an irregular manner, surface soft spots are created due to local hot spots which are more sensitive to the pressure of the inner molten metal. The aforesaid conditions make it mandatory that the present casting operations be extremely and unduly delicate, requiring constant, precise and exact control at the great risk of experiencing repeated breakouts.

Another serious difficulty with respect to the present low level casting arrangement stems from the improper degree of curvature of the sections that follow the mold. Heretofore, not only were objectionable stresses being imposed upon the cast product before sufiicient solidification had taken place, 'but the degree of curvature imparted to the cast product wa not correlated sufficiently to the condition of the cast product to assure continuously satisfactory performance.

The present invention is addressed to a novel casting machine which overcomes each and every one of the aforesaid difficulties and still incorporates the benefits that inure from the employment of a low level casting arrangement and adapted for use in casting rounds, billets, and particularly wide slabs.

Among the features of the present invention is the providing of an arrangement whereby the cast product is not bent until there has been formed a skin thickness of a safe dimension as well as a cooler and, therefore, stronger skin.

In one arrangement an oscillating mold is employed having straight, vertical parallel walls. To the lower end of the mold there is provided for oscillation in unison therewith, a straight first portion of a secondary cooling section in which there is a minimum and non-varying gap between the mold and the first portion of the secondary cooling section. The total vertical dimension of these two elements is such that the cast product is maintained in a straight, unbent condition and free from any bending stresses incident to causing the cast product to assume the horizontal position until suflicient solidification and cooling of the outer walls occurs and until the cast product passes below the location where detrimental internal washing action occurs due to stream penetration.

In the second preferred arrangement the lower end of the straight oscillating secondary cooling section is followed by a stationary secondary cooling section having a short straight section followed by a curved portion designed to impose a progressively controlled low-bending strain to the cast product to gradually curve it from the vertical to the horizontal and before total solidification takes place, preferably at or before 75% of total solidification. Following the lower end of the curved secondary cooling bending section is a curved secondary cooling section having the same radius as the secondary cooling bending section. In the preferred arrangement the radii of the curved sections of the secondary cooling zone are of the order of a ratio between 30 to 50 to 1 to the thickness of the cast product.

These features, as well as others, will be better understood when the accompanying specification is read in light of the attached drawings of which:

FlIGURE l is an elevational view of a continuous casting plant incorporating the features of the present invention;

FIGURE 2 is an enlarged sectional view of the mold and upper portion of the secondary cooling section illustrated in FIGURE 1;

FIGURE 3 is an enlarged elevational view, particularly, of the mold and secondary cooling section oscillating mechanism illustrated in FIGURE 1;

FIGURE 4 is an enlarged diagrammatic view of the equipment illustrated in FIGURE 1, particular emphasis being placed on the pinch roll and leveling unit and dummy bar mechanism;

FIGURE 4a is a section taken on lines 4a-4a of FIG- URE 4; and

FIGURE 5 is an enlarged sectional view of the automatic disengageable starter head and transition section of the dummy bar mechanism shown in FIGURES 1 and 4.

In first referring to FIGURE 1 which, as indicated above, is an elevational view of an entire structural platform 10 which is supported by two rows of vertical columns, two columns being shown at 11, the platform 10 being designed to support part of the casting machine and, particularly, the housing of the casting mold assembly 12, the tundish car 13 which carries a tundish 14. The tundish car 13 is brought to and moved away from the mold by virtue of wheels 15 secured thereto which run over rails 16 supported by the platform 10. Molten metal of a specific temperature range is delivered to the tundish 14 and, hence, to the mold from a ladle 17 which, as shown, is supported by a hook 1 8, although it could be supported by a permanent structure support, the hook being attached to the hoist of an overhead crane, not shown. Towards the left of FIGURE 1 there is shown an overflow ladle 19 into which overflow metal from the tundish 14 is directed through a trough 21 according to well-known practice.

As shown in FIGURE 2, below the mold assembly 12 and attached thereto, as will be more specifically noted hereinafter, there is a relatively short, straight secondary cooling section 22. The mold assembly and short attached secondary cooling section 22 are mounted on a platform which is oscillated in a vertical direction by a drive 23 which is connected to the lower portion of the mold assembly 12 through links 24 and 25. At the lower end of the oscillating secondary cooling section 22, there is provided a stationary short, straight section 26 followed by the curved stationary secondary cooling section 27 which imparts the initial curvature to the cast product. It will be noted in FIGURE 1 that the cast product which takes the form of a billet B is shown issuing from the casting machine, having been guided by a curved secondary cooling section 27a that follows the cooling section 27, both being formed with the same radii.

At the lower end of the curved cooling section 27a there is provided a pair of pinch rolls 28, the axes of which, while contained in a common plane, are offset towards the casting machine relative to a vertical plane. Following the pair of pinch rolls 28 is a second pair of pinch rolls 29, the axes of which are contained in a common plane perpendicular to the horizontal. After a pair of pinch rolls 29, there is a support roller 31 which is, in turn, followed by a third pair of pinch rolls 32. The pinch rolls 2.9 and 32 in combination with the roller 31 in addition to advancing the cast product serve to bevel it. It should be pointed out at this juncture that each of the three sets of pinch rolls are driven by a means, not shown, and the upper rolls are vertically adjustable by piston cylinder assemblies 33. It will be noted in more detail hereinafter that upper roll of the third pair of pinch rolls 32 is em ployed to automatically disengage the head of the dummy bar mechanism from the billet B, it being noted in FIG- URE 1 that the upper roll in question is adapted to be raised into a position considerably away from the billet B. Adjacent the delivery side of the pair of pinch rolls 32, there is provided a curved trough 34 which supports and guides a dummy bar mechanism 35 which is made up of flexible members that enable it to take the curved path dictated by the trough 34. The bar 35 is advanced towards and away from the casting machine by a pair of pinch rolls 36 driven by a means not shown and supported by the platform 10. It will be noted from FIGURE 1 that when the upper roll of the pair of pinch rolls 32 is in its upper position, as indicated in phantom, the dummy bar is free to pass beneath it, as is somewhat better shown in FIGURE 4.

Following the pair of pinch rolls 32 is a shear 37 which is advanced by a piston cylinder assembly 38 in the direction of travel of the cast product so as to effect a cut of a particular length without requiring a discontinuation of the casting operation. The shear 37 may take the form of several types and since it is not a part of the present invention, the particular details thereof will not be given. The billet B issuing from the shear 37 is received by a runout table 39 which, in the usual manner, is made up of power-driven rollers 40.

Turning now particularly to the construction of the mold assembly 12 and the short attached straight cooling section 22, particular reference is made to FIGURES 2 and 3. With reference first to the mold assembly, it is made up of a construction similar to what is customarily employed, having an outer stationary housing 41 to which there is secured and guided for vertical movement therein an inner platform or housing 42, the lower end of which extends below the housing 41 and is constructed in the form of a pair of opposed arms to which there is connected the outer ends of the link 25 that oscillates the inner housing 42 relative to the outer housing 41. Secured to the top of the inner platform 42 is an annular crosspiece 43 to which is secured the inner and outer walls of a water cooling passageway. To the bottom of the outer wall 45 is secured an annular crosspiece 44. Adjacent to the inner surfaces of the inner wall 45, there is provided the usual copper mold liner 46 that makes up the mold proper and against which the molten metal contacts and is thus rapidly cooled. Below the crosspiece 44 there is provided an extending member 47 which includes a ring 48 secured to its lower end and to which is secured the top portion of the straight section of the secondary cooling section 22. As FIGURE 2 clearly shows, the copper mold cooling liner 46 extends through the extending member 47 and its lower end terminates adjacent the first rollers of the secondary cooling unit 22 so that there is a minimum and non-varying gap between the two members and the two members can be so aligned mechanically as to form but one continuous straight passageway for the solidifying cast product.

The short attached secondary cooling section 22 consists of a number of sets of rollers 49 which, in the illustrated form number ten, each set being made up of four rollers arranged in a common plane which engage the four sides of the billet B. These rollers are not driven, but are freely rotatable upon contact with the advancing billet. Behind the rollers 49 there are provided water spray headers for each side of the cast product, two of which are shown at 51 and 52. The water headers 51 and 52 will deliver coolant, such as water, under high pressure to the billet to enhance its rapid cooling and internal solidification, while in the straight, unbent condition.

It is important to point outwith respect to the particular illustrated employment of the invention tha the aggregate vertical dimension of the mold liner 46 and the straight attached secondary cooling section 22 forms a passageway of approximately 6 feet, which dimension, as previously noted, relates to the depth of the penetration of the stream so as to assure that no bending of the cast product will take place above the lowest point. of stream penetratration or with respect to a given molten material or casting condition if bending does occur above the point it will only be allowed to the extent that the skin of the cast product is thick enough and cool enough to give maximum assurance against a breakout as well as assure quality of cast product. Since the straight section 22 is attached to and oscillates with the mold assembly 12, there is assured that during the critical period, when the thin skinned cast product is transferring from the mold assembly I12 to the roller spray type secondary cooling zone 22 that there will be no gap variation between the mold assembly nor chance for mechanical misalignment, thereby resulting in a uniform cooling and solidification of the internal molten metal without mechanical stresses due to either gap variation or mechanical misalignment. These advantages are most important in working with rimming steels.

The advantages of providing the short attached straight section 22 as an integral part of the mold assembly whereby it will oscillate therewith can be best appreciated when it is considered that for the product being considered, the degree of solidification of the walls as the cast product leaves the mold assembly will be only on the order of A" to /2". It is extremely important, therefore, that there be no disturbance with respect to the portion of the cast product passing from the mold assembly, such as would be experienced in bending the cast product or having a varying space or gap between the mold assembly and secondary casting section or a slight misaligning between these two members. As previously noted, the present invention provides an arrangement that is freed from all effects of these conditions and wherein the bending of the skin thickness of the cast product issuing from the section 22 will occur either below or in a safe area above the stream penetration zone and where the solidified skin is of a sufficient thickness that the possibility of breakthrough will be considerably reduced. In the illustrated form the thickness can typically range from A to 1 /2" thickness for a 5" square billet, which is about 15% to to 30% of the total thickness.

For casting wide slab products the above described arrangement possesses some noteworthy advantages. Since the cast product is formed and maintained in the straight vertical position until a sufficient skin thickness is obtained, during which period the penetration stream is symmetrical and bending is delayed relative to the penetration stream and cooling and the gravitational effect is equalized, the product is assured of being maintained in a regular symmetrical slab form.

Not only for the reason already mentioned, is it important not to bend the cast product until a sufficient skin has been formed, but it is also important not to delay bending after a certain point in the solidification process. If the bending process is delayed too long, in addition to requiring considerably more force to effect the bending and increasing the length of the plant, objectionable internal stresses may develop and surface defects. According to the teaching of the present invention, the bending process should be consummated on or before approximately 75% solidification takes place, and as much before this point as possible, recognizing of course the requisites of allowing a sufiicient skin to be formed. In terms of the illustrated example of the present invention, as previously noted, the solidification of the cast product as it enters the curved stationary cooling section 27 falls between 15% and 30%.

Still referring to FIGURE 2 and to the lower end of the equipment there shown, it will be noted that after the cast product leaves the secondary cooling section 22 and after a short straight initial passage in the stationary section 26 and only then, is it allowed to be subject to a gradual bending process by the curved portion of the secondary cooling section 27 which is carefully developed to assure that the billet surface will not be subject to harmful strains. As shown in FIGURE 2 the stationary secondary cooling section 27 is carried by a frame 53 which also supports one end of the curved cooling section 27a. The cooling section 27 is made up of a number of sets of rollers 54, which, in the case illustrated, number ten, each set consisting of four rollers arranged in a common plane and adapted to engage the four sides of the solidifying billet. The billet is also subject to coolant during its passage through the secondary cooling unit 27, for which purpose there is provided cooling headers and sprays 56 and 57. As previously noted, in describing the equipment shown in FIGURE 1, following the secondary cooling unit 27 is the additional cooling section 27a which is generated about a radius similar to the radius used to generate the section 27 of the secondary cooling section.

As previously noted, the degree of the radius employed in deflecting the cast product from the vertical to the horizontal must be such as not to overly strain the surface of the hot thin skinned, pliable billet. It has been found that a cast product formed in the above-described manner can be very successfully handled by employing a radius of thirty to fifty times the thickness of the cast product. In the illustrated case the strain of outer fiber is only about 1% percent with a 30 to 1 ratio of radius to thickness. It is also important to note that in the disclosed arrangement no positive pressure is imposed on the cast product itself during the transition period from the straight to the curved, since the curvature is imposed by the roller necklace of the sections 27 of the secondary cooling section by a series of progressive bends.

In now referring to FIGURE 3, which contains an enlarged view of the mechanism provided for oscillating the mold assembly and second cooling section 22, as previously noted, the platform 42 of the mold assembly 12 is provided with a pair of downwardly projecting arms, the lower ends of which are connected to the links 25. The links 25, which extend in a horizontal direction, are pivoted about a trunnion bracket 58. The links 25 are connected at their outer ends to the links 24 which, as noted previously, extend in a vertical direction, the lower ends of which are connected to a lever 59, which is trunnion mounted on a bracket 61. The opposite ends of the lever 59 has a cam roller 62 which engages a driven cam 63. The cam is mounted on a shaft 64 which runs in a gear drive 65 and which, in turn, is driven by an electrical motor 66. The lever 59 at its end adjacent to the links 24 is spring-biased in an upward direction by a spring 67, thereby assuring positive contact between the roller 62 and the cam 63. Stop screw 68 is provided to hold up the lever 59 when the cam 63 is being changed. FIGURE 3 also serves to better illustrate the supporting structure for the secondary cooling sections 22 and 26, it being noted that the outer housing 69 thereof is carried by a platform 70 which in FIGURE 1 is shown supported on two vertical columns.

Attention is now directed to FIGURES 4 and 4a which are primarily addressed to the novel dummy bar mechanism 35 herein disclosed. As previously noted, one of the features of the present invention is to provide a compact dummy bar arrangement which will not increase the size or layout of the casting plant. In this connection, FIGURE 4 illustrates the feature wherein the trough 34 that received the dummy bar mechanism 35 when inoperative is curved in a manner to overhang the pinch rolls 28, 29 and 32. As FIGURE 4 illustrates, the dummy bar mechanism is positioned inside the mold assembly 12 being initially guided in the curved trough 34 which is best seen in FIGURE 4 1, At the front of the mechanism and protruding therefrom is a starter bolt or plug 71 of a removal head 72. The head 72 and starter bolt are better illustrated in FIGURE 5. Returning to FIGURE 4, following the head 72, the dummy bar takes the form of replaceable flexible transition section 73 made of sufficient length to extend through with the secondary cooling sections 22, 26 and 27 and into the first portion of secondary cooling sections 27a. From this point, the dummy bar consists of a curved rigid bar identified as 74 which is made of sufficient length to extend from a position where the head 72 is inside of the lower portion of the mold assembly 12 to where it is engaged by the pinch rolls 28 and 29.

In turning now to FIGURE 5, which is an enlarged view of the dummy bar starter head 72, it will be appreciated that, as previously noted, the portion of the head adjacent to the cast product is replaceable as well as the transition section to correspond with the particular size cast product being cast. As FIGURE 5 shows, the starting bolt or plug 71 of the head 72 passes into an opening 75 into which is received a pin 76. The head takes the form of an L having formed thereon a vertical cylinder end 77. This end is received in an opening 78 in a member 79 of the transition section 73 of the dummy bar mechanism. In the member 79, directly across from the cylindrical portion 77, there is provided a detent ball 80 which is forced into engagement with the portion 77 by virtue of a spring 81, received in a hole 82 provided in the member 79. The construction of the cylindrical portion 77 and the ball 80 is such that upon displacement of the head 72 downward the connection is quickly broken and the member 79 is freed from the head 72. The member 79 consists, as indicated previously, of a number of flexible sections which are pinned together in chain-like fashion. FIGURE 5 shows three of these sections, namely, sections 83, 84 and 85, which are pinned together by pins 86.

Returning now to FIGURE 4 which illustrates, in phantom, the employment of the upper roll of the pair of pinch rolls 32 to disengage the member 79 of the transition section 73 from the starter head 72 and the cast product. As shown, the dummy bar mechanism 35 and the cast product have advanced to a position immediately under the upper pinch roll 32. Once in this position the piston cylinder assembly 33, shown only in FIGURE 1, that moves the upper pinch roll vertically will be actuated to force the starter head 72 away from the member 79 of the transition section 73, thereby disengaging the cast product and starter head from the transition section 73. The upper pinch roll 32 will then be held down in the lower position to cause the cast product to pass into the shear 37 where the leading end will be sheared off and starter head 72 removed after it has cooled. Once the disengagement has been accomplished, the pinch rolls 36 can pull the dummy bar mechanism 35 away from the pinch rolls 32 into a position as shown in phantom in FIGURE 4. In this location, the fresh starter head is snapped into position into member 79 on top of the transition section 73 of the dummy bar mechanism.

In accordance with the provisions of the patent statutes, I have explained the principle and operation of my invention and have illustrated and described what I consider to represent the best embodiment thereof. However, I desire to have it understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

I claim:

1. In a method of continuously casting ferrous product, wherein the product is cast in a vertical position and thereafter caused to assume a horizontal position for conveyance away from the casting machine, and wherein during the casting process a stream of material penetrated the interior of the partially solidified cast product, comprising the steps of:

discharging molten material into an open-ended mold to effect initial solidification of the walls of the taining the cast product in a straight, unbent condition cast product; after it issued from the oscillating secondary cooling secoscillating the mold in a vertical direction in unison tion and thereafter causing the cast product to commence with a secondary cooling section arranged to imto assume a horizontal position.

mediately follow the mold; and 5 3. In a method of continuously casting a product, accreating a continuous, uninterrupted passageway by cording to claim 1, the additional step of delaying the said mold and secondary cooling section into which commencing of the bending of the cast product from the the cast product passes for cooling to avoid breakvertical position to the horizontal position at least until outs and maintaining a proper configuration of the a point below the lowest point of stream penetration.

cast product, said passageway being of a height suf- 10 ficient to maintain the cast product in a straight, ere CeS C ted unbent condition and free from any bending stresses UNITED STATES PATENTS incident to initiating the bending of the cast product from a vertical to a horizontal position until sufag at g2 ficient solidification and cooling of the outer wall 1 2895190 7/1959 B m an TTT' occurs and until below the location where detri- 3283368 11/1966 e a mental internal washing action occurs due to stream 41 12/1966 man .f X penetration, and thereafter causing said cast product 31 6/1967 B 55011 i 2 to be deflected from the vertical position to a horiungelrot at a 1 8 X zontal position and while the center portion thereof 20 FOREIGN A TS is still molten and applying a tension force to the solidified skin of said cast product during the direc- 1353998 1/1964 France tional change from the vertical to the horizontal.

2. In a method of continuously casting a product, ac- SPENCER OVERHOLSER Pr'mary Exammer' cording to claim 1, including the additional step of main- 25 R. S. ANNEAR, Assistant Examiner.

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