1. Field of the Invention
The present invention relates, in general, to metal making apparatus and, specifically, to molten metal receptacles and, more specifically, to a slag control shape loading device used in molten metal vessels.
2. Description of the Art
In metal making processes, such as steel making, molten metal is transferred from a furnace or converter by a ladle to a tundish or directly to a casting machine. In all metal making processes, and, in particular, in steel making processes, a layer of slag containing metal impurities forms above the top surface of the molten metal within the ladle and the tundish. When the molten metal is discharged from the ladle or tundish, it is necessary to maintain a separation between the slag and the molten metal so that high quality steel without significant amounts of slag can be produced.
The slag forms a layer of impurities several inches thick on top of the layer of molten metal in the ladle and in the tundish. In addition, the flow of molten metal through the discharge nozzle in the ladle or tundish creates a vortex which introduces a conically-shaped rotation to the molten metal immediately above the discharge nozzle. When a sufficient quantity of molten metal is maintained within the ladle or tundish, the vortex forms completely within the molten metal layer and does not reach to the slag layer atop the molten metal layer. However, when the level of molten metal within the ladle or tundish drops below the predetermined critical depth, the vortex reaches into the slag layer and draws slag through the center of the vortex to the discharge nozzle along with molten metal. This causes the introduction of slag into the molten metal as it is discharged from the ladle or the tundish and results in steel having less than desirable quantities as well as creating a potentially hazardous situation.
In order to prevent the introduction of slag into the molten metal, various slag control shapes, such as balls, frusto-conical bodies, etc., as shown in U.S. Pat. Nos. 4,725,045 and 4,968,007, are introduced into the transfer ladle or tundish. Such slag control shapes or bodies have a predetermined specific gravity less than the specific gravity of the molten metal and greater than the specific gravity of the slag layer so that the slag control shape or body is buoyantly supported at the interface between the slag layer and the molten metal layer. Such slag control bodies or shapes are also designed to locate and center themselves automatically in the vortex formed above the discharge nozzle from the molten metal vessel or receptacle. The lower portion of such slag control bodies is disposed in the molten metal layer and will enter and seat within the upper portion of the discharge nozzle of the molten metal receptacle when the molten metal layer drops below a predetermined depth so as to block the discharge nozzle and prevent the discharge of slag from the receptacle.
While such slag control bodies or shapes have found widespread use and effectively block the undesirable discharge of slag from a molten metal vessel, such as a transfer ladle or tundish, the introduction of such slag control bodies into the molten metal receptacle has proved to be a problem.
Typically, such slag control bodies are introduced into the transfer ladle or tundish at a predetermined time during the discharge of molten metal from the ladle or tundish. The time of insertion of the slag control body is based on an operator's experience, typically on the total time of molten metal discharge, or on a potentially inaccurate vessel or ladle weight reading from a load cell in a ladle weight system. As ladles positioned in caster turret arms are typically 20 feet or more in height, overhead cranes have been used to drop the slag control body into the ladle at the point in time indicated by an operator. However, such cranes are assigned numerous other tasks which make it difficult to insure that a crane is available at the precise time that the operator determines it necessary to insert the slag control body into the molten metal vessel.
A small number of metal making or casting machine installations have a stairway located adjacent the discharge position of a ladle which enables a worker, such as a ladleman, to climb to the top of the ladle and insert the slag control body into the ladle at the required time. However, the height of the ladle, the approximate 25 pounds or more weight of the slag control body, and the high temperatures involved in the molten metal process make such a task difficult, undesirable and dangerous. Further, the ladleman typically has other duties in monitoring the metal making process which must be neglected for the time it takes to climb the stairs and insert the slag control body. Dedicating one person solely to the task of inserting the slag control body into the molten metal vessel at the required time adds costs to the metal making process as such an individual is only required is to perform his single task at widely spaced, intermittent intervals.
Further, when such slag control shapes are dropped into a molten metal vessel, they typically fall from 10 to 15 feet before hitting the slag layer. Due to the buoyancy characteristics of a slag control shape and its momentum during dropping into the vessel, the slag control shape will initially pass through the slag layer and into the molten metal and then bob up out of the molten metal and slag until it settles at the molten metal/slag interface. However, this bobbing force and the inherent buoyancy characteristics of a slag control shape frequently cause the slag control shape to settle at a position away from a desired position directed above the discharge outlet of the molten metal vessel. Indeed, it is infrequent for the slag control shape to settle directly over the discharge outlet since the discharge outlet is typically 2½ to 4½ inches in diameter as compared to the 10 to 20 foot diameter of a typical ladle. Thus, when a vortex begins to form above the discharge outlet when the molten metal reaches a low level within the ladle or vessel, the slag control shape may not be able to reach the vortex in time to serve its function of blocking the outlet to prevent the discharge of slag through the outlet. Furthermore, even if the slag control shape initially settles directly over the discharge outlet, it frequently drifts away since a vortex may not have formed above the outlet and never returns to the desired centered position thereby defeating its intended purpose.
In order to address these problems, one of Applicants' previously devised a slag control shape release apparatus which is disclosed in U.S. Pat. No. 5,249,780 issued on Oct. 5, 1993. In this apparatus, the hanger of a slag control shape extends through a bore in a molten metal vessel cover and, also, through a bore in a lid pivotally mounted on the cover. A pin is mounted on the lid and biased to a position extending through the hanger to support the slag control shape on the cover. An actuating cable is connected to the pin and extends from the cover to an easily accessible position for remote actuation of the release mechanism to release the pin from the slag control shape and to allow the descent of the slag control shape into the molten metal vessel.
A similar release apparatus has also been devised by one of the Applicants and is disclosed in U.S. Pat. No. 5,303,902 issued on Apr. 19, 1994. In this apparatus, a mounting means including a reciprocally movable pin is mounted on a frame pivotally mounted on the cover of a molten metal vessel and is actuated by a cable extending from the pin to a free end remote from the cover. A cable wound around a reel mounted on the frame is attached to the slag control shape to control the descent of the slag control shape into the molten metal vessel after release from the pin.
Yet another release apparatus has been devised by one of the Applicants' and is disclosed in U.S. Pat. No. 5,423,522, which issued on Jun. 13, 1995. In this release apparatus, a lid is removably implacable in a bore in the cover. The hanger or rod of a slag control shape extends through the lid and is releasably received in mounting means on the lid. The actuating means is similar to that in the other release devices devised by the Applicants' in that it is in the form of a cable having an end operable from a location remote from the cover on the molten metal receptacle. In this latter design, means are provided for releasably connecting the actuating means to the mounting means after the mounting means and the lid have been mounted on the cover. This enables the heavy mounting and activating means to be mounted on the lid rather than on the cover which is typically formed of lightweight refractory or ceramic fiber materials.
In the slag control apparatus, also devised by one of the Applicants, and shown in U.S. Pat. No. 5,421,560, issued on Jun. 6, 1995, the mounting means of the slag control shape release apparatus includes a frame fixedly mounted on a lid and slidably supporting a tubular pin. The pin supports the hanger of the slag control shape at one end. A biasing means mounted on the frame normally biases the pin to a first position. The actuating means is releasably connected to the mounting means for actuating the mounting means to release the slag control shape. The actuating means is also operable from a location remote from the cover. In one embodiment, a weight control means determines the weight of the ladle indicate the amount of molten metal remaining in the receptacle. At an appropriate preset weight, a controller transmits a radio frequency signal to the actuating means to automatically release the slag control shape into the molten metal receptacle.
While all of these apparatus have proved effective at accurately dropping a slag control shape into a molten metal vessel and permitting the timely release of the slag control shape from an easily accessible location remote from the cover on top of a molten metal vessel, all except the latter release apparatus require the manual intervention of the ladleman or operator at the proper time to pull the cable to release the slag control shape from the cover. Despite the close location of the end of the cable connected to the actuating means in each of these release devices to the operator, the operator is still required to move at least a short distance to grasp and pull the cable. Thus, it would be desirable to provide a slag control shape release apparatus for use with a molten metal receptacle or vessel which enables an operator to release a slag control shape into the receptacle from a location more convenient or closer to the usual location of the operator or ladleman on the casting platform adjacent to the ladle.
A slag control shaped release apparatus for a molten receptacle is disclosed which includes a sleeve connected to the metal receptacle or an adjacent base. An L-shaped bracket is mountable to the sleeve wherein the L-shaped bracket is rotatable relative to the sleeve. The bracket has means for releasably mounting a slag control shape in which the mounting means is movable between a first position releasably mounting a slag control shape and a second position releasing the slag control shape for falling into the molten metal receptacle, the means for releasibly mounting the slag control shape includes a spring biased sliding pin.
In another aspect of the invention a rotatable shaft is disposed between the sleeve and the L-shaped bracket. The rotatable shaft is a cylindrical member having a through center aperture extending the length of the shaft and diametrically opposing pegs extending from the shaft in a central portion of the shaft.
Further, in another aspect of the invention the sleeve has a top surface with a plurality of notches formed therein for receiving the diametrically opposing pegs.
In yet another aspect of the invention, a horizontal portion of the L-shaped bracket includes a bar carrying the means for releasibly mounting the slag control shape including a bracket sleeve having a portion connect to the bar and a movable portion carried on a slide pin.
The various features, advantages and other uses of the present invention will become more apparent by referring to the following detailed description and drawing in which:
a are top elevational views of the horizontal section illustrating a bracket sleeve in a closed position and opened position, respectively;
As shown in
By way of background, the molten metal vessel or ladle 10 includes outer, side walls 16 typically formed of a metallic outer shell and an inner layer formed of a refractory material, such as firebrick, etc. An open top end 22 is formed on the ladle 10. A discharge nozzle or outlet 24 is formed in a bottom wall 26 of the ladle 10 and provides an outlet path for molten metal from the ladle 10 to a tundish casting machine, etc.
As is conventional, a slag control shape or body denoted generally by reference number 32 in
According to the present invention a slag control shape release apparatus 30 is provided for inserting a slag control shape body 32 into the vessel 10 at the appropriate time determined by an operator or ladlemen monitoring the metal making process. The release apparatus 30 includes a means for releasably mounting the slag control shape or body 32 over the vessel 10 for moving the mounting means between first and second positions and actuating means for moving the mounting means from the first position to the second position, the actuating means operable from a position remote from the vessel 10.
The apparatus 30 also includes means for selectively rotating the apparatus into selective positions away from or over the vessel 10. The rotating means allows the slag control shape body 32 to be mounted to the release apparatus 30 when the release apparatus 30 is rotated away from the vessel 10. The rotating means prevents the release apparatus 30 from rotating during the mounting process. After the body 32 is mounted, the release apparatus 30 can be rotated again to extend the body 32 over the vessel 10.
As shown in
The L-shaped bracket 40 includes a vertical portion 50 that is connected into the sleeve 42 and a horizontal portion or arm 52 connected at an upper end to the vertical portion 50. An angle brace 51 can extend between and connect the vertical portion 50 and arm 52. The vertical portion 50 is a cylindrical, tubular bar having a through aperture therein. The arm 52 extends 90° from the vertical portion 50. The vertical portion 50 has one end 54 connected into the rotating shaft 56. As seen in
The horizontal arm 52 carries a delivery mechanism assembly as shown in
A bracket sleeve 72 is located at the opposing end of the slide pin 62 from the handle 68. The bracket sleeve 72 maintains the stem 33 of the slag control body 32 in an upright, vertical orientation. The spring 70 is biased to maintain the sleeve 72 in a closed position as seen in
The second portion 80 of the bracket sleeve 72 includes a short metallic bar 82 secured to the free end of the slide pin 62. The short bar 82 is teed in connection to a second short bar 84 which is also connected by welding or other conventional means to one edge of another arcuate portion 86 formed from a thin walled pipe. The thin walled pipe 86 is sized such that the inner surface 88 accommodates the outer surface of another portion of the arcuate tubing 90. The second arcuate tubing 90 is positioned within the thin walled pipe 86 so that when the bracket sleeve 72 is in a closed position, as shown in
As can be seen in
The arm 52 of the delivery mechanism assembly further carries a lock pin 64 along its axial length. The lock pin 64 maintains the bracket sleeve 72 in an open position for placement of the slag control shape or body 32. The lock pin 64 is slidable held along the arm 52 by a plurality of collars 96. The collars 96 are similar to the collars 66 on the slide pin 62 and are secured to the lock pin 64 in the same manner. Looking at
In summary the L-shaped loading bracket as disclosed for sue with molten metal vessels 20 which enables a slag control shape body 32 be easily inserted into the molten metal vessel at the appropriate time without an operator manually inserting the slag control body into the vessel 10. The apparatus is conveniently mounted on a platform adjacent to the edge of the vessel 10; or directly on the edge of the vessel 10. The L-shaped bracket can be initially rotated away from the vessel for connection of the slag control shape body thereto. The diametrically opposing notches 48 hold the pegs 60 of the rotating shaft 56 in place to prevent movement of the L-shaped bracket 40 during connection of the slag control shape body 32. After the slag control shape body is installed on the L-shaped loading bracket 40,the bracket 40 can be rotated so that the slag body 32 extends over the vessel 10. The delivery mechanism provides a quick manual release of the slag body when the operator determines the appropriate moment.
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