US3433287A - Dummy bar device for continuous casting machine - Google Patents

Description

March 1969 J. 1. GREENBERGER 7 9 DUMMY BAR DEVICE FOR CONTINUOUS CASTING MACHINE Original Filed Jan. 11, 1965 Sheet of 4 M rch 8. 1969 .1. GREENBERGER DUMMY BAR DEVICE FOR CONTINUOUS CASTING MACHINE Sheet g of4 Original Filed Jan. 11. 1965 A 7' 7 OIQNEK Mam]! 1969 J. 1. GREENBERGER 3,433,287

DUMMY BAR DEVICE FOR CONTINUOUS CASTING MACHINE Sheet Q of 4 Original Filed Jan. 11, 1965 m HN M rch 8, 96 J. GREENBERGER 3, 3,

DUMMY BAR DEVICE FOR CONTINUOUS CASTING MACHINE Sheet Original Filed Jan. 11, 1965 8 MN 5 W 1 M E m J ATTORNEY.

United States Patent 3,433,287 DUMMY BAR DEVICE FOR CONTINUOUS CASTING MACHINE Joseph I. Greenberger, Pittsburgh, Pa., assignor to United Engineering and Foundry Company, Pittsburgh, Pa., a corporation of Pennsylvania Original application Jan. 11, 1965, Ser. No. 424,779, now Patent No. 3,370,641, dated Feb. 27, 1968. Divided and this application May 18, 1967, Ser. No. 655,696 U.S. Cl. 164-274 Claims Int. Cl. B22d 11/08 ABSTRACT OF THE DISCLOSURE The present disclosure relates to an improved dummy bar assembly for use in a continuous casting machine. The invention also is addressed to a novel and useful pinch roll dummy bar arrangement.

This application is a division of Ser. No. 424,779 filed Jan. 11, 1965 which has issued into Patent No. 3,370,641.

A serious problem in present low level casting plant designs is the inability to design the dummy bar to economically and conveniently cooperate with the curved elements of the secondary cooling as well as the runout sections. Furthermore, there has been a great need for a dummy bar arrangement which will allow automatic and simple detachment of the dummy bar head from the frozen end of the m st product.

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

It is an object of the present invention to provide a novel pinch roll and leveling unit for receiving the cast product as it approaches the horizontal direction of travel having for one of its features the use of pinch rolls to automatically disengage the cast product from the dummy bar head.

A further object of the present invention is to provide an essentially permanent dummy bar section to which may be secured different size, replaceable transition sections and starter heads designed to cover the whole range of the products produced by the casting machine, in which the starter heads are constructed to be automatically disengageable from the dummy bar. The dummy bar includes flexible members which not only permit the bar to be guided through the short straight as well as the curved secondary cooling sections, but will also allow it to be located in an out-of-the-way position above the pinch roll and leveling unit when not in use, thereby affording a very accessible and compact arrangement.

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

FIGURE 1 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 18, 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 270 that follows the cooling section 27, both being formed with the same radii.

At the lower end of the curved cooling section 2711. 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 29 and 32 in combination with the roller 31 in addition to advancing the cast product serve to level 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 employed to automatically disengage the head of the dummy bar mechanism from the billet B, it being noted in FIGURE 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 F 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 3 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 powerdriven 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 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 rnold 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 out with respect to the particular illustrated employment of the invention that 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 penetration or with respect to a give 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 12 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 /4" 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 ctfects 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 sufiicient thickness that the possibility of breakthrough will be considerably reduced. In the illustrated form the thickness can typically range from to 1 /2" thickness for a 5" square billet, which is about 15% 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 suflicient skin thickness is ob tained, 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 and symmetrical slab form.

Not only for the reason already mentioned, is it important not to bend the cast product until a suflicient 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 sufficient 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 sec tion 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 /3 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 4a. 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 replace-able flexible transition section 73 made of sufficient length to extend through 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 sufiicient 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. A continuous casting machine, including a mold and first and second secondary cooling sections arranged in a sequential vertical relationship adapted to cool a cast product, wherein the cast product is caused to assume a horizontal position for conveyance away from the machine:

a curved trough for supporting and guiding a dummy bar, said trough displaced from the horizontal path of travel of the cast product;

a portion of said dummy bar being made up of a flexible transition section, which portion is of a length sufiicient to extent through the first and second secondary cooling sections and the lower portion of said mold; and

means for moving said dummy bar towards and away from said mold.

2. A continuous casting machine, according to claim 1, in which the dummy bar includes a permanent section and wherein said transition section is replaceably connectable to said permanent section to accommodate cast products of different physical sizes;

the replaceable transition section having a coupling member including a projection to which the cast product adheres upon solidification thereof;

said permanent section having a coupling member; and

means for causing said coupling members to be quickly engaged and disengaged from each other.

3. A continuous casting machine, according to claim 2, including means for engaging one of the coupling members of said dummy bar to cause their disengagement.

4. A continuous casting machine, according to claim 2, in which a pair of pinch rolls are arranged to engage the cast product after it leaves said first and second secondary cooling sections;

means for moving one of the pin rolls towards and away from the other pinch rolls;

said movable pinch roll adapted to be brought into engagement with the cast product to cause it to be released from the coupling member of said permanent section, whereby the cast product is allowed to pass away from the casting machine without interruption of its travel.

5. A continuous casting machine, according to claim 1, wherein there is provided a plurality of transition heads corresponding in size to the variable sizes of products cast by the casting machine.

6. In a continuous casting machine including a mold,

a secondary cooling trough having at least a curved portion and arranged at the delivery end of said mold for guiding a cast product away from said casting machine,

a dummy bar constructed and arranged to pass into said secondary cooling trough from the delivery end of the trough and to present a portion into the mold for engagement by a cast product formed in the said mold,

means for storing said dummy bar located adjacent to the delivery end of said cooling trough and out of the path of movement of the cast product and in a manner to allow the cast product to pass unrestrictedly in said path, and

means for advancing said dummy bar between said mold and said storage means.

7. In a continuous casting machine, including a ver tically arranged, opposed open ended mold, a curved trough arranged so that its upper end receives a cast product from the mold and its lower end extends in a generally horizontal plane for guiding a product away from the casting machine,

a dummy bar constructed and arranged to pass into said trough from its lower end and to present a pertion into said mold for engagement by a cast product formed in said mold,

means for storing said dummy bar when not in use located adjacent the casting machine and out of the path of movement of said cast product so as to al low the cast product to pass unrestrictedly in said pass path, and

means for advancing said dummy bar between said mold and said storage means.

8. In a continuous casting machine according to claim 7, including a straightening machine for straightening the cast product passing from said curved trough and for advancing said dummy bar between said mold and storage station,

said straightener located in said horizontal plane between the lower end of said trough and said dummy bar storage means.

9. In a continuous casting machine according to claim 7, including a pair of pinch rolls,

means for positioning one of the pinch rolls to one side of said path and with reference to said path on the same side as said storage means, adapted to engage the cast product in such a manner to disengage it from the dummy bar.

10. In a continuous casting machine according to claim 7 wherein said means for storing said dummy bar includes a curved trough for guiding and supporting the dummy bar when in its storage position, and

means for supporting said last-named curved trough above said path of movement of said cast product and substantially in the same vertical plane.

References Cited UNITED STATES PATENTS 2,891,294 6/1959 Muller et a1. 164--120 2,920,359 l/ 1960 Easton et al. 164269 2,947,075 8/1960 Schneckenburger et al.

164283 X 3,262,162 7/1966 Lemper 164274 3,324,934 6/1967 Hess et al 164274 3,344,844- 10/ 1967 Reinfeld et al. 164282 X I. SPENCER OVERHOLSER, Primary Examiner.

R. SPENCER ANNEAR, Assistant Examiner.

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