US2571033A

US2571033A - Apparatus for pouring molten metal

Info

Publication number: US2571033A
Application number: US2114A
Authority: US
Inventors: Jr Isaac Harter; Temple W Ratcliffe
Original assignee: Individual
Current assignee: Babcock and Wilcox Tube Co
Priority date: 1948-01-13
Filing date: 1948-01-13
Publication date: 1951-10-09
Anticipated expiration: 1968-10-09

Description

1.951 I. HARTER, JR, ETAL 2,571,033

APPARATUS FOR POURING MOLTEN METAL Filed Jan. 13, 1948 I 2 Sheets-Sheet 1 INVENTORS [saac Harzer; Jr: &' BY Ym le WKaZc/iffb A TTYORNE'Y 1951 LHARTER, JR., EI'AL 2,571,033

APPARATUS FOR POURING woman METAL ATTORNEY Patented Get. 9, 1951 APPARATUS FOR POURING MOLTEN METAL Isaac Harter, Jr., Beaver, Pa., and Temple W. Ratcliife, Westfield, N. J., assignors to The Babcock & Wilcox Tube Company, West Mayfield, Pa., a corporation of Pennsylvania Application January 13, 1948, Serial No. 2,114

Claims.

1 The present invention relates in general to the casting of metals, and more particularly to the pouring of molten slag-containing metals.

In the casting of metals containing slag contaminants, it is desirable to eliminate or reduce the contaminants to the lowest degree possible before the delivery of the molten metal to a mold and the subsequent solidification of the casting. The presence of the slag contaminants in a casting are detrimental to its value and commercial acceptability, and while minor amounts of slag in or on an ingot are sometimes tolerated, the complete or partial elimination of the slag is highly desirable. Slag contaminants are particularly prevalent in the production of ferrous alloy castings such as steel. Ferrous metals are customarily melted under slagging conditions, and, as is also well known, the metals readily oxidize in contact with air at molten metal temperatures and chemically react with practically all of the known refractory materials in contact therewith, forming ferrous and ferric compounds collectively known as slag.

The presence of slag contaminants in the molten ferrous metals delivered to a continuous casting mold, as an example, is particularly deleterious due, in the main, to their insulating value. In the continuous casting process, any slag carried into the mold with the molten metal will tend to collect on the periphery of the casting. This will tend to insulate the contiguous portion of the casting wall from the heat removal efiect of the adjacent mold, so that the shell strength of the casting may be insufflcient to withstand the ferrostatic pressure imposed thereon, resulting in a rupture of the casting shell. It has also been observed that where the solidification of a portion of the casting is delayed, even though ruptureof the well does not occur, the subsequent solidification of the interior portion of the casting frequently results in an unequal circumferential cooling of the casting and the formation of shrinkage cracks or voids in a portion of the casting.

The art is well aware of the adverse effects of metal splashing" in top pouring metal into a mold, but its deleterious efiect is accentuated in the continuous casting of metals wherein the general cause of splashing is closely related to other problems more specific to a continuous casting process. Splashing is commonly caused by the improper delivery of metal from an excessive height above a mold and in an off-centered location with respect to the axis of the mold. In continuous casting, an off-center delivery of molten metal and/ or an excessive height of metal fall to the level of the molten metal within the mold not only causes splashing, but also encourages turbulence of metal within the mold which tends to prevent the formation of a circumferentially uniform wall thickness. It is also beneficial to reduce the length of fall of the molten stream in order to reduce the chance of metal oxidation.

The principal object of the present invention is to provide apparatus for the controlled delivery of molten metal to a casting mold, A further and more specific object is to provide apparatus of the character described for the separation of slag contaminants from molten ferrous alloys and the delivery of clean metal to a casting mold. An additional specific object is to provide apparatus of the character described capable of delivering a stream of substantially slag-free molten metal to a continuous casting mold under regulated conditions of delivery position and a substantially uniform molten metal delivery velocity.

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

Of the drawings:

Fig. l is an elevation, partly in section, of a tun dish and its operating mechanism constructed in accordance with the present invention as interposed between a tilting ladle source of molten metal and a continuous casting mold, taken on line ll of Fig. 4;

Fig. 2 is an elevation view of the tun dish, taken along the longitudinal centerline thereof, as shown by the line 2-2 in Fig. 3.

Fig. 3 is a plan view, partly in section, of the tun dish and its support;

Fig. 4 is a front elevation view, partly in section, of the tun dish and its support; and

Fig. 5 is a section taken on line 5-5 of Fig. 4.

While various features of the present invention are adapted for use in the casting of metals, the apparatus herein described is particularly advantageous for use in the continuous casting of carbon and alloy steels and other slag-forming metals.

In the continuous casting of metal, the molten 3 e -metal, such as steel 'or other metal or alloy is introduced into the upper end of an upright mold, solidified therein by heat exchange with a cooling fluid and withdrawn from the opposite lower end of the mold. Such a continuous casting system and the apparatus therefore is disclosed and claimed in a co-pending application of I. Harter, I. Harter, Jr. and O. R, Carpenter, Serial No. 16,956, filed February 26, 1948. The molten metal is delivered to a holding and pouring ladle I from which it is poured at a selected rate and an optimum temperature through a pouring lip in one side thereof into a tun dish II for delivery into a continuous casting mold assembly I2. The ladle I0 is shown schematically inFig. 1 in its relationship with the tun dish and the mold assembly. As shown in the co-pending application, the ladle is arranged for tilting motion about a horizontally disposed axis of rotation defined by trunnions I3 projecting outwardly on opposite sides of the ladle body. The position of the ladle I 0 is also adjustable in a horizontal direction so that-the stream of metal discharged from the ladlemay be selectively positioned while the rate of discharge therefrom is regulated by the angle of ladle tilt. v

The tun dish II of the present invention is arranged to receive the molten metal from the ladle I0 and to discharge the metal-into the open end of the mold assembly I2. The mold assembly is disclosed and claimed in the previously mentioned copending application and includes, in general. a vertically elongated molding tube I4 encircled by a horizontally disposed flange member I5 at its upper end. An annular fluid chamber I6 surrounds the upper end of the tube I4 and is defined by the flange I5, a transverse plate member I9 and an outer cylindrical wall H. An inner cylindrical sleeve I8 is spaced from the outer surface of the tube I4 and extends upwardly from the member I6 to a position spaced'from the flange I 5. A cylindrical skirt '20 extends downwardly from a position adjacent the upper end of the sleeve I8 in closely spaced relationship with the molding tube I4 to define an annular cooling fluid flow passageway 2I therebetween substantially the length of 'the mold. An annular, perforated distributing plate 22 is positioned intermediate the height of the chamber I8 between a plurality of cooling fluid inlets 23 and a flared inlet 24 of the passageway2l. With this construction the molten metal is solidified in the mold assembly by heat exchange through the tube I4 to a. high velocity stream of cooling fluid passing through the passageway 2|.

Experience has shown that the most sati factory casting results are attained by the delivery of molten metal to the center of a pool of molten metal maintained in the upper portion of the molding tube in a substantially slag-free condition and under substantially uniform fiow conditions; Best casting results are obtained with a low velocity of molten metal delivery. The temperature of the metal'and the rate of its delivery is obtained by proper control of the pouring ladle I0, but the accurate regulation of optimum metal delivery position within the mold is determined by adjustment of the tun dish I I. The tun dish is also constructed and operated to minimize the inclusion of slag in the continuous casting and to provide a maximum visibility of the metal within the mold.

The tun dish II is shown in detail in Fig. 2 and consists of a metallic outer casing 32 having an inner refractory lining 32a and a layer of *tlon with the inclined baffle the inlet chamber 25 and extends upward at an angle of approximately 20-30, with its lower end merging into the vertical partition 27. The lining and bellies are made of any suitable high temperature refractory material. Holes 30 in the bottom of the vertical-partition 21 below its junc- 28 form a plurality of separate passages, or in some cases a single passage, through which the molten metal can flow-from the inlet to the outlet chamber of the tun dish. A V-notch refractory weir 3| is formed in the end wall of the tun dish for the discharge of the molten metal. In operation, the tun dish is preheated to a high temperature, normally tilted forwardly about 10 and positioned so'that the stream of molten metal from the ladle Ilfalls into the inlet chamber 25 and strikes the vertical partition 27 below the normal molten metal level therein at such an angle that the stream continues to descend until it strikes the inclined baflle 28, which deflects the metal entrapped slag to the surface. The rising impetus given to the molten stream and the entrapped slag is most important because the slag being lighter endeavors to separate from the heavier metal and also readily adheres to other slag that has previously come to the surface. The slagfree metal then flows over the end of the inclined baffle 28 and through the passages 30 in the vertical baiile to the outlet chamber 26, from which it flows over the V-notch weir 3I.

The described construction of the tun dish is effective in separating slag from the moltenmetal delivered thereto and isalso eflective in maintaining an essentially uniform velocity in the stream of metal delivered to the mold assembly.

This is largely accomplished by the

bailles

21 and 28, in that the stream of metal entering the chamber 25 contacts a pool of "molten metal therein which absorbs ity of the entering metal stream, with the stream thereafter reversing its direction of flow as directed by the bullies. The reversal in the direction of metal fiow tends velocity of the entering metal stream. The flow of molten metal over the upper end of and beneath the baflle 28 toward the passages 30 consequently moves substantially under the influence of the difference in metal head between the pools of metal in the inlet and outlet chambers. In this manner, the velocity of the stream of metal entering the mold assembly l2 from the tun dish is at a minimum and is not appreciably influenced by changes in the metal velocity as delivered to the tun dish.

Due to the effectiveness of slag separation with the construction described, the tun dish may be of a minimum size for an advantageously small volume occupied by the molten metal therein. Consequently a sorbing and heat radiating surfaces, and the use of heat insulating materials results in a substantial elimination of heat loss from the molten metal while passing through the tun dish.

The tun dish II is supported at a predeteran arm 33. The arm is pivotally arranged for a major share of the veloc-.

to absorb the remaining low area of heat ob-- movement in a horizontal plane so that the tun dish can be generally positioned relative to the mold, and when not in use the arm and tun dish may be swung away from the vicinity of the mold. A more accurate positioning of the tun dish relative to the mold is obtained by a plurality of adjusting movements of the tun dish relative to the arm 33. These movements include tilting the tun dish about a horizontal axis intersecting the crest of the weir 3|; angular movement of the tun dish in a horizontal plane about a vertical axis; and a straight line lineal movement of the tun dish in a horizontal plane. These motions are primarily for the purpose of correcting any misalignment of the metal-stream which may be caused by frozen metal on the weir or on the weir of the pouring ladle l0, and thus enable the operator to accurately direct the stream of metal into the center of the molten pool in the mold. p

As shown particularly in Figs. 3 and 4, the arm 33 is pivotally mounted at one end in a socket bearing 34 on a post which is secured to the supporting structure of the continuous casting apparatus. A friction brake 35 is provided to secure the arm in a selected position adjacent the mold assembly I! so that the tun dish is generally positioned for the delivery of molten metal to the mold.

A metal platform or plate 35 is pivotally attached to the arm 33 and directly supports the tun dish II by means of pedestals 31 carrying the trunnion bearings 32. The pivotal connection between the arm and the plate is provided by a pivot pin 38 closely fitted through the plate 35 and extending through a slotted opening 41 in the arm 33. The pivot maintains the arm and plate in vertical relationship while permitting a horizontal rotational movement of the plate relative to the arm and thus defines a vertical axis A-A, The vertical axis AA intersects the longitudinal axis of the tun dish intermediate the length thereof, and although the horizontal position of the pin 38 may be altered relative to the arm 33, within the limits of the slotted opening 48, the vertical axis AA will be maintained in a fixed position relative to the tun dish.

The tun dish is supported by trunnions 4| extending outwardly from opposite sides thereof and resting in the bearings 33 to provide an axis B -B of tilting rotation intersecting the crest of the V-notch weir 3|. One of the trunnions M is provided with a depending lever arm 42 keyed thereon which is contacted by a crank screw 43. The screw 43 is threaded through a block 44 fastened to the plate 36 so that the lever arm can be moved through an arc about the axis B--B to regulate the angle of tilt of the tun dish.

Angular movement of the tun dish in a horizontal plane about the pivot pin 38 and verticalv axis AA is effected by a screw crank '45 rotatably mounted in an axially fixed position in a ring 45 on an extension arm 41 of the plate 3'5 and engaging a pivoted nut 48 on an arm 50. The right hand end portion of the arm 50, as viewed in Figs. 3 and 4, lies in an open-ended recess formed in the top of arm 33, and is pivotally connected to the plate 36 by the pin 38. The top of the arm 58 is flush with the top of the arm 33, and the sides of the recess guide a the arm 58 in a horizontal straight line movement as hereinafter described. with this construction the radius of the block 48 and ring 45 relative to the pivot 38 are fixed while the in-.

engaging the flange 52 carries a laterally procluded aims therebetween ls adjustable about the pivot 38 by the screw crank 45.

The lateral movement of the tun dish H in a jecting threaded bolt 54 which engages a turn nut 55. The turn nut is mounted in a bearing support 55 aflixed to the arm 33 so that rotation of the nut moves the bolt 54 and alters the position of the plate 36 relative to the arm '33 within the limits defined by the longitudinal dimension of the slotted opening 40. The lateral position of the plate 35 relative to thearm 33 will be maintained regardless of the angularity therebetween as selected by adjustment of the screw crankas long as the relationship of the bolt 54 and nut remain constant. This is due to the arcuate shape of the fiange 52 and slide 53.

The nut 55 is conveniently rotated by means of a crank and the meshing

bevel gears

51 and 58. with the gear 58 mounted on the crank shaft 53 which is supported in the bearings 6| ailixed to the arm 33.

In operation, the molten metal is lip-poured from the ladle ill to enter the previously de scribed entrance end of the tun dish H and to discharge from the opposite end thereof into the mold II. The rate of molten metal fiow into the mold is ordinarily regulated by controlling the ladle III with the angle of tilt of the tun dish maintained at an adjusted value during the pouring period. The partition 21 and the inclined baffle 28 cooperate to divert the flow direction of the entering stream of metal so as to absorb the velocity head thereof in the pool of metal maintained in the tun dish and to encourage the separation of slag from the molten metal. The molten metal thereafter passes beneath the iriclined baflle and. through a plurality of submerged passageways 38 in the lower portion of the partition into the outlet chamber of the tun dish. In this manner slag is separated from the metal and the metal will discharge from the pouring lip of the tun dish under substantially uniform velocity flow conditions into the mold. It will be observed that the velocity of the molten metal stream delivered to the mold will be maintained at a generally uniform low velocity head which is substantially independent of the stream velocity entering the tun dish. Such flow velocity conditions are particularly important in a cont nuous casting process, in that turbulence within the mold is large y avoided and optimum circumferential uniformity of metal cooling is encouraged.

The tun dish is provided with a supporting mechanism therefore which is arranged to position the stream of metal delivered to themoldf "'he. arm 33 is positioned so as to generally locate the tun dish H relative to the mold assembly l2. Ordinarily the angle of tilt of the tun dish about 'the axis of rotation BB is maintained at approximately 10 as hereinbefore described. However, the angle of tilt'can be adjusted during operation of the apparatus, if pouring conditions indicate the desirability of such an adjustment. A change in the tilting angle will change the position of metal stream delivery to the mold assembly I! in a direction normal to the axis BB. Since the axis intersects the crest of the weir 3|, the vertical height of the falling molten stream will not vary substantially, with respect to the top of the mold assembly I2, after a change in theangle of tilt of the tun dish.

The angular movement of the tun dish about its vertical axis AA, as obtained by adjustment of the screw crank 45, causes a movement of the stream of metal entering the mold through an are centered on the pivot pin 38. The lineal straight line movement of the tun dish, as attained through rotation of the shaft 60, causes a lineal movement of the vertical axis A-A in a direction. determined by the slotted opening 40 and the position of the arm 33. As shown in Fig. 3, the direction of lineal movement is generally normal to the longitudinal axis of the tun dish. With a change in the included angle between

arms

41 and 50, however, the lineal movement of the tun dish will not be necessarily normal to its longitudinal axis, although the direction will remain the same as before, relative to the arm 33 and the mold assembly l2.

It will be noted that the supporting mechanism for the tun dish of the present invention provides an accurate adjustment for positioning the delivery point of the molten metal discharged from the weir 3|. The adjustable motions include a general adjustment in a horizontal plane about a fixed pivot point, and a plurality of fine adjustments for accurately locating the stream of molten metal discharged from the tun dish. The latter adjustments include a tilting motion of the tun dish about a horizontal axis, an angular movement in a horizontal plane about a vertical axis, and a lineal movement in the same horizontal plane.

While in accordance with the provisions of the statutes we have illustrated and described herein the best form and mode of operation of the invention now known to us, those skilled in the art will understand that changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by our claims, and that certain features of our invention may sometimes be used to advantage without a corresponding use of other features.

We claim: a

1. Apparatus for regulating the position of a stream of molten metal delivered to a casting mold comprising a lip-pour tun dish, an arm movable in a horizontal plane about a fixed bearing support, a plate mounted upon said arm. means for directly supporting said tun dish on said plate for tilting movement about a transverse horizontal axis, a pivot pin in vertical alignment with said tun dish fitted to said plate and slideably engaging a slotted opening in said arm, means for moving said plate in an arc about said pivot pin, and means for moving said plate in a transverse horizontal direction.

2. Apparatus for delivering a stream of molten metal to a subiacent casting mold comprising a pouring vessel, an arm horizontally disposed above said mold and having a pivotable bearing support at one end thereof, a plate directly sup.-

porting said vessel and resting upon said arm. and a vertically arranged pivotal attachment beneath said vessel between said arm and plate and slideably engaging a slotted opening in said arm.

3. Apparatus for delivering a stream of molten metal to a subjacent casting mold comprising a lip-pour vessel, an arm horizontally disposed above said mold and having a pivotable bearing support at one end thereof, a plate bearing on said arm and directly supporting said vessel for tilting movement about a transverse horizontal axis, and means for angularly and laterally shifting the position of said plate relative to said arm including a laterally shiftable pivot pin connection between said arm and plate defining a vertical axis, the lateral movement of said vertical axis changing the dimension between said bearing support and said vessel.

4. Apparatus for regulating the position of a stream of molten metal delivered to a casting mold comprising a lip pour tun dish, a horizontally disposed arm positioned above said casting mold and having a pivotal support at one end thereof, a plate bearing upon said arm and directly supporting said tun dish for tilting movement about a transverse horizontal axis, said axis intersecting the pouring lip of said tun dish normal to the direction of molten metal flow from said tun dish, and a pivotal connection between said arm and plate for substantially horizontal movement of said tun dish in an are about said pivotal support, said pivotal connection consisting in a pin fixed in said plate and movable in a slot in said arm elongated in a direction generally radial with respect to the end pivotal support of said arm.

5. Apparatus for regulating the position of a stream of molten metal delivered to a casting mold comprising a lip pour tun dish, an arm movable in a horizontal plane about a fixed bearing support radially spaced from said tun dish, a plate mounted upon said arm, a trunnion support for said tun dish mounted directly on said plate for tilting movement of the tun dish about a transverse horizontal axis, a pivot pin in vertical alignment with said tun dish fitted to said plate and slideably engaging a slotted opening in said arm, a screw-crank mechanism arranged to move said plate in an are about said pivot pin, and a separate screw-crank mechanism arranged to move said plate and tun dish in a transverse horizontal direction. v ISAAC HARTER, JR. TEMPLE W. RATCLIFFE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS