US3274653A

US3274653A - Quickly disconnectable starter bar

Info

Publication number: US3274653A
Application number: US333449A
Authority: US
Inventors: Justin E Foldessy; Andrew L Poulos
Original assignee: United States Steel Corp
Current assignee: United States Steel Corp
Priority date: 1963-12-26
Filing date: 1963-12-26
Publication date: 1966-09-27
Anticipated expiration: 1983-09-27
Also published as: ES307368A1; FR1535422A; GB1088597A; NL6415077A; BE657278A

Description

Sept. 27, 966 J. E. FOLDESSY ETAL 3,274,653

QUICKLY DISCONNECTABLE STARTER BAR Filed D80. 26, 1963 2 Sheets-Sheet 1 INVENTORS- F l JUSTIN E. FOLDESSY AN DREW L. POU L05 ATTORNEY Se t. 27, 1966 J. E. FOLDESSY ETAL 3,274,653

QUICKLY DISCONNECTABLE STARTER BAR 2 Sheets-Sheet 2 Filed Dec. 26, 1963 INVENTORS J U S T IN E, F O L D E SSY BY AN DR EW L. P 0 U LO 8 ATTORNEY United States Patent 3,274,653 QUICKLY DISCONNECTABLE STARTER BAR Justin E. Foldessy, Ogden Dunes, and Andrew L. Poulos, Ross Township, Lake County, Ind., assignors to United States Steel Corporation, a corporation of Delaware Filed Dec. 26, 1963, Ser. No. 333,449 2 Claims. (Cl. 2257.2)

This invention relates to apparatus for the continuous casting of metals and more particularly to starter bars used in continuous casting.

It is customary in the continuous casting of metals to provide an apparatus comprising a vertical tubular mold open at the upper end for receiving molten metal and open at the lower end for the discharge of a metal casting, cooling means comprising a plurality of water sprays located below the mold for directing cooling water against the casting, guide means comprising a plurality of guide rolls located between the water sprays for guiding the casting as it moves downwardly through the cooling zone, and motor driven pinch rolls located below the guide rolls and cooling means. The cooling means are mounted on a suitable immovable frame. The guide rolls and pinch rolls are mounted for rotation in suitable mountings, which are also mounted on an immovable frame.

It is necessary to close the lower discharge end of the mold initially when molten metal is being poured into the mold. This is usually done by the insertion of a starter bar into the bottom of the mold. The starter bar is an elongated metal bar, usually solid and rigid, which has a cross-sectional shape approximately the same as that of the mold with a slightly smaller cross-sectional area in order to permit ready insertion of the bar upwardly through the guide rolls and into the bottom of the mold. The starter bar, in addition to closing the discharge end of the mold while molten metal is being poured, also supports the metal column or casting as it descends through the guide rolls and pinch rolls.

After the starter bar has passed through the pinch rolls, it is severed from the casting. One or more cutting torches located a short distance below the pinch rolls are usually employed for the purpose. These torches cut the casting a short distance above the top of the starter bar. The starter bar, with a short length of casting attached to the top thereof, is lowered vertically, supported by a suitable platform, basket, or the like. At the bottom of its vertical travel, the starter bar is lowered to a horizontal position and transported horizontally away, by power driven rollers for example. The short length of casting attached to the starter bar must be removed before the starter bar can be used again.

Different ways have been suggested for handling the casting (excluding the short length which remains attached to the starter bar) after its severance from the starter bar. According to one way, the casting is cut into lengths by cutting torches and lowered vertically and then transported horizontally in the same manner as the starter bar. According to another mode of operation, the casting after severance from the starter bar is deflected from its vertical path, by a horizontally reciprocable roll known as a pusher roll for example, and guided in a curved path from the vertical direction to the horizontal by means of rolls mounted in a guide frame. The casting is straightened when it reaches a generally horizontal position. If desired, the casting after straightening may be reheated if necessary and rolled.

Cutting the casting to separate the starter bar as above described has at least tWo disadvantages.

Firs-t, it is necessary to remove the short length of casting which remains attached to the starter bar after cutting. This must be done manually, often requiring considerable time and labor.

Second, cutting of the casting a short distance below the pinch rolls requires that the entire cross-section of the casting be solid by the time it reaches that point. This in effect means that the casting must become completely solidified in the cooling zone above the pinch rolls. Since the casting is traveling vertically throughout the cooling zone, an apparatus of considerable height is required.

It is an object of this invention to provide a starter bar which can be quickly and completely disconnected while said starter bar and casting travel downwardly.

It is a further object of this invention to provide a starter bar having secured to the top thereof a chill plate which is quickly releasable from the starter bar.

In the drawings:

FIG. 1 is a top plan view, partly in section, of a starter bar in accordance with this invention.

FIG. 2 is a side elevation, with parts broken away and parts in section taken along .along line 2-2 of FIG. 1.

FIG. 3 is a section looking downwardly along line 33 of FIG. 2.

FIG. 4 is a fragmentary sectional view taken along line 44 of FIG. 3.

FIG. 5 is an isometric view of a starter bar and casting attached thereto.

FIG. 6 is an isometric view of the starter bar after detachment from the casting.

Referring now to the drawings and especially to FIGS. 1 to 4 thereof, 10 indicates generally a starter bar which is adapted to be inserted into the lower portion of a tubular open ended continuous casting mold indicated generally at 12. The mold may be of any cross-sectional shape desired, but in the usual practice a rectangular mold is used. Starter bar 10 generally is an elongated metal body, which may consist either of a single piece or of a plurality of sections which are detachable from each other and joined together by suitable means such as the mortise and tenon joint 14 illustrated in FIG. 2. However, relatively short starter bars or plugs embodying the quick release mechanism to be described herein are also within the scope of this invention.

A metallic chill plate 16 rests on top of starter bar 10 and is releasably secured thereto. This plate as illustrated herein is a fiat plate, resting on a fiat top surface of starter bar 10. The chill plate serves four main purposes: to protect the starter bar from direct contact with the molten metal poured into the mold, to chill and solidify the molten metal along the entire surfiace of the chill plate, to grip the solidified casting firmly, and to provide means for quick disconnection of the starter bar from the casting with no part of the casting adhering to the starter bar.

Chill plate 16 has a plurality of cylindrical pins 17 projecting upwardly from its top surface. Pins 17 have heads 17a which are of somewhat greater diameter than the pins themselves. Pins 17 engage the lower end of the casting in interlocking engagement and thus anchor the casting to chill plate 16.

Chill plate 16 as seen from above is preferably of the same size and shape as the top section of starter bar 10. The top section of the starter bar may have the same dimensions as the remainder of the bar, although frequently it is desirable for the top section to be slightly smaller than the remainder of the bar in both width and thickness to facilitate insertion into the mold. The contour of the top of starter bar 10 is the same as that of chill plate 16. Thus, in the embodiment shown, chill plate 16 and the top surface of starter bar 10 are both flat. However, chill plates which are not flat, as for exproximately the same.

ample dished chill plates, or chill plates in the shape of a trough, are also within the scope of the invention.

Chill plate 16 is preferably made of a metal, which must have a melting point not lower than that of the metal or alloy being cast. Advantageously the composition of the chill plate and the metal being cast are ap- Thus, when a low carbon steel is being cast, the chill plate is advantageously made of low carbon steel. Metal is preferred to refractory as a chill plate material because of its higher heat transfer rate and faster solidification of the surface of the casting abutting the chill plate.

The chill plate must be thick enough to chill and freeze the molten metal of the casting along the entire surface of the chill plate and to prevent melting of the plate from the heat of the molten metal. At the same time it is highly desirable for the chill plate to be thin enough so that it will be heated throughout by the molten metal to a temperature high enough for rolling. This is advantageous because it is desirable to roll the metal casting without first removing the chill plate therefrom. Chill plates of about /2 inch thick have been found to be very suited to the casting of ferrous metals and alloys. The chill plate should be at least about A inch thick so that it will freeze the entire surface of the metal abutting the chill plate and so that no holes extending through the entire thickness will be melted therein. The chill plate should not be substantially thicker than /2 inch, because excess thickness increases the possibility that the plate will become too cool for rolling before that stage of operations is reached. Plate 16 is thin enough not to interfere with the guide frame which directs the casting through a curved path from the vertical to a horizontal direction.

The starter bar has a pair of

recesses

18 and 19 adjacent the top of the bar. A pair of opposed, parallel side walls 20a and 20b encloses recess 18 on two sides thereof. Similar side walls 21a and 21b enclose recess 19. Each of these recesses is open to the exterior of bar 10 along a third side and along the top. Portions of the top and of two

opposite sides

22 and 23 of bar 10 adjacent the top are cut away to provide these exterior openings. A barrier 24 separates the two

recesses

18 and 19. Barrier 24 is of substantial thickness and extends to the top of starter bar 10, providing a portion of the surface on which chill plate 16 rests. The remainder of this surface is provided by the top surfaces of

side walls

20a, 20b, 21a and 21b, which extend to the same height as barrier 24 when a flat chill plate 16 is used. The bottom of

recesses

18 and 19 are defined by surfaces 25 and 25a respectively.

The depth of

recesses

18 and 19 is suflicient to accommodate the latches to be hereinafter described for securing plate 16 to starter bar 10. Excess depth beyond that required is to be avoided, since excessive cut out portions weaken the starter bar.

Recesses

18 and 19 have portions 18a and 19a respectively, which extend downwardly along

side walls

22 and 23 of the starter bar 10 below the level of surfaces 25 and 25a. These portions 18a and 19a are narrower than the

recesses

18 and 19, and extend a much smaller distance inwardly from

side walls

22 and 23.

According to this invention the chill plate 16 is secured to the starter bar 10 by means of a pair of

latches

26 and 27, which are mounted in

recesses

18 and 19 respectively. These latches are mounted for rotation on pivot pins 28 and 29 respectively, which are secured in

side walls

20a, 20b and 21a, 21b respectively.

Latches

26 and 27 are identical in construction. Latch 26 has one outwardly projecting arm 30 which extends from pivot 28 to a point near the end wall of starter bar 10, and also has a second arm 32 which extends upwardly and terminates in a hook portion 34. Latch 27 has an outwardly projecting arm 31 and an upwardly projecting arm 33 terminating in hook 35.

Chill plate .16 has welded thereto and depending therefrom a pair of

U-shaped brackets

36 and 37 which are adapted to receive

latches

26 and 27 respectively when the latches are in the closed position.

When the upper end of starter bar 10 with chill plate 16 attached thereto is inserted into the lower end of a tubular continuous casting mold 12, a small gap extends around the entire perimeter of the chill plate 16 between the plate and the mold, due to the slight difference in cross-sectional area between the plate 16 resting on bar 10 on one hand and mold 12 on the other. Entry of molten metal into this gap can be prevented by means of a heat resistant seal such as annular asbestos rope 42 or other suitable sealing means.

FIG. 5 shows a starter bar 10 of this invention, plate 16, and metal casting 43 attached thereto, during descent of said starter bar and casting at a position below the mold and above the elevation at which the starter bar is disconnected from the casting. The speed of descent of the starter bar and casting is controlled by pinch rolls 44.

Disconnection of starter bar 10 from chill plate 16 and casting 43 attached thereto is accomplished by means of air cylinders 45 and 45a, and their

respective pistons

46 and 47 and

piston rods

46a and 47a, which constitute striker arms for releasing

latches

26 and 27 respectively, as shown in FIGS. 5 and 6. These cylinders 45 and 45a, are located a fixed short distance above pinch rolls 44 and in positions laterally outwardly from the path assumed by starter bar 10 and casting 43 during their descent. Both cylinders 45 and 45a and the mountings for the shafts of pinch rolls 44 are rigidly mounted on fixed supports, and preferably on the same supporting structure.

Arms

46a, 47a are normally retracted away from the edges of starter bar 10, as shown in FIG. 6. To release bar 10 from plate 16,

striker arms

46a, 47a are extended to the position shown in FIGS. 2, 3, 4 and 5 when latches 26, 27 are slightly above the elevation of the arms. The starter bar 10 and casting 43 continue to descend while the

striker arms

46, 47 maintain their positions. This causes the

latches

26, 27 to be moved from the closed position to the open position shown in dotted lines in FIG. 2. In that position, starter bar 10 can be lowered separately from chill plate 16, which remains attached to casting 43.

Striker arms

46a, 47a are retracted after the

latches

26, 27 are moved to the open position.

Striker arms

46a, 47a can be operated in any desired manner. In a preferred embodiment, they are operated automatically when starter bar 10 reaches a predetermined elevation.

Various automatic actuation systems for opening latches 26 and 27 can be used in connection with this invention. A particularly advantageous actuation system is the one described in the co-pending application of Justin E. Foldessy and Francis Gallucci, filed of even date herewith and entitled Continuous Casting Apparatus Having a Quickly Disconnectable Starter Bar. A sensing device 50 is used to determine when the proper elevation for disconnecting starter bar 10 from plate 16 and casting 43 has been reached. This sensing device comprises an air cylinder 51 having a piston 52 therein, a piston rod 52a projecting through both ends of the cylinder, and a limit switch 53 to which piston rod 52a is attached at one end. Cylinder 51 is mounted on a fixed supporting structure, preferably the same as that which supports pinch rolls 44 and cylinder 45, at a fixed predetermined elevation above pinch rolls 44 and below cylinder 45. The end of .piston rod 52a which is nearest to the path of starter bar 10 and casting 43 in their descent (i.e., the end opposite the end attached to limit switch 53) serves as a follower which is adapted to ride along side wall 22 of starter bar 10 as the bar descends and to enter notch 48 when said notch reaches the elevation at which cylinder 51 is located. According to this system, the starter bar 10 is provided with longitudinally extending

notches

48 and 49, which are placed on

side walls

22 and 23 of starter bar 10, so

that these walls may be used interchangeably if desired. Air is admitted to air cylinder 51 on the right side of piston 52 as starter bar is descending, so that the end of piston rod 52a rides against the side 22 of the starter bar. When notch 48 reaches the elevation at which cylinder 51 and piston rod 52a is located, the end of piston rod 52a enters the notch, which closes limit switch 53. Closing of limit switch 53 causes air to be admitted to cylinders 45 and 45a so as to move the

respective pistons

46 and 47 and

striker arms

46a and 47a to the position shown in FIGS. 2 to 5 inclusive, wherein they cause latches 26 and 27 to open as starter bar 10 descends, thereby releasing starter bar 10 from chill plate 16 and casting 43. Starter bar 10 after disconnection from the chill plate 16 and casting 43 is lowered on a vertically traveling basket 54.

Other automatic actuation systems besides the one illustrated can be used. If desired, sensing mechanism 50 can be omitted and the admission of fluid under pressure to cylinders 45 and 45a can be under the control of an operator.

Operation according to this invention will now be described with particular reference to FIGS. 5 and 6. Prior to the start of a casting, the upper end of starter bar 10 with chill plate 16 attached is inserted into the lower end of an open ended tubular continuous casting mold 12. Molten metal is then poured into the mold until it reaches a predetermined elevation near the top thereof. When this predetermined elevation is reached, the starter bar 10 and casting 43 are slowly brought downward at a uniform rate under the control of pinch rolls 44 (FIG. 5). The outer surface of skin in casting 43, and the lower end of casting 43 which abuts chill plate 16, solidify while the casting is still in the mold and before movement of the starter bar downwardly is commenced. Solidification of casting 43 around the heads of cylindrical pins 17 provides a tight interlock between the casting and plate 16.

After the height of metal in the mold has reached a predetermined level, starter bar 10 and casting 43 are brought slowly downward to the predetermined elevation at which the starter bar is to be disconnected from the casting. At that point it is desirable to detach the starter bar from the casting as quickly as possible. The starter bar, being of substantial length and inflexible, must be brought straight downwardly by suitable means such as a basket which is indicated diagrammatically at 84 in FIGS. 5 and 6. The

latches

26, 27 in starter bar 10 can be quickly tripped to the release position, whether manually or automatically, so as to permit starter bar 10 to be brought down independently of casting 43. Starter bar 10 is then brought rapidly downward, while casting 43 and chill plate 16 and pins 17 attached thereto continue to descend at a slow control rate still under the control of pinch rolls 44. This phase of operations is best illustrated in FIG. 6, which shows the starter bar after it is disconnected from the casting. After the starter bar 10 has been taken out of the way and casting 43 continues to descend through lower pinch rolls 44, the casting may be further handled in any desired means. For example, the casting may be cut into sections by conventional cutting torches (not shown) located below pinch rolls 44. Alternatively the casting may be deflected to a horizontal position (the casting still being quite hot and relatively plastic), after which it may be further handled in any desired manner.

The starter bar is completely separated from the casting in the present invention, with no part of the casting remaining attached to or adhering to the starter bar,

This is in contrast to apparatus used hereto-fore, in which the casting is cut with cutting torches a short distance up from the end at which said casting is attached to the starter bar. Such procedure leaves a short length of casting attached to the bar.

One advantage of the novel apparatus herein is that less work is necessary to ready the starter bar for re-use than is the case in prior art apparatus where a small length of casting must the removed from the starter bar. Because no part of the casting is attached to the starter bar after disconnection, the time spent in removing the small length of casting attached to the bar after cutting according to the prior art is not required.

Another advantage is that the starter bar can be disconnected from the casting much more quickly than a casting can be cut with cutting torches as is necessary when previously known starter bars are used.

While this invention has been described with respect to specific embodiments thereof, it is understood that it shall be limited only by the scope of the appended claims.

What is claimed is:

1. In a continuous metal casting apparatus comprising a mold of rectangular cross-section in which metal is cast, a plurality of guide rolls below the mold for guiding a metal casting as it descends, and pinch rolls below said guide rolls for controlling the rate of descent of the casting, the improvement comprising a chill plate of rectangular cross-section slightly smaller than that of said mold for closing the bottom of the mold when the metal is first cast, a rigid starter bar for connection to said plate to support the plate until the cast metal solidifies thereon and becomes attached thereto and to then move the plate and casting downwardly and thus start the casting process, the top section of said starter bar being of the same cross- -sectional size and shape as said chill plate and having a pair of recesses therein, a pair of latches respectively located in said pair of said recesses, each of said latches being pivotally mounted on said starter bar for rotation about a horizontal axis and including an outwardly extending arm and an upwardly extending arm terminating in a hook for securing said chill plate to said starter bar, and means located exteriorly of said starter bar for engaging said outwardly extending arms when said top section of said starter bar reaches a predetermined elevation between said mold and said pinch rolls in its descent and for holding said arms against downward travel with the bar long enough to disengage said starter bar from said chill plate and the attached casting.

2. Apparatus according to claim 1 wherein said means for engaging said outwardly extending arms comprises a pair of horizontally movable striker arms mounted at fixed predetermined elevations on said pinch rolls and below said mold, said striker arms being adapted to be moved inwardly from their normal position in the line of travel of said starter bar wherein they engage said outwardly extending arms and thereby cause said starter bar to be released from said chill plate.

References Cited by the Examiner UNITED STATES PATENTS 648,091 4/ 1900 Trotz 2257 .2

FOREIGN PATENTS 729,359 5/ 1955 Great Britain.

J. SPENCER OVERHOLSER, Primary Examiner.

MA ROUS U. LYONS, R. 'S. ANNEAR, R. A. SANDLER,

Assistant Examiners,

Claims

1. IN A CONTINUOUS METAL CASTING APPARATUS COMPRISING A MOLD OF RECTANGULAR CROSS-SECTION IN WHICH METAL IS CAST, A PLURALITY OF GUIDE ROLLS BELOW TE MOLD FOR GUIDING A METAL CASTING AS IT DESCENDS, AND PINCH ROLLERS BELOW SAID GUIDE ROLLS FOR CONTROLLING THE RATE OF DESCENT OF THE CASTING, THE IMPROVEMENT COMPRISING A CHILL PLATE OF RECTANGULAR CROSS-SECTION SLIGHTLY SMALLER THAN THAT OF SAID MOLD FOR CLOSING THE BOTTOM OF THE MOLD WHEN THE METAL IS FIRST CAST, A RIGID STARTER BAR FOR CONNECTION TO SAID PLATE TO SUPPORT THE PLATE UNTIL THE CAST METAL SOLIDIFIES THEREON AND BECOMES ATTACHED THERETO AND TO THEN MOVE THE PLATE AND CASTING DOWNWARDLY AND THUS START THE CASTING PROCESS, THE TOP SECTION OF SAID STARTER BAR BEING OF THE SAME CROSSSECTIONAL SIZE AND SHAPE AS SAID CHILL PLATE AND HAVING A PAIR OF RECESSES THEREIN, A PAIR OF LATCHES RESPECTIVELY LOCATED IN SAID PAIR OF SAID RECESSES, EACH OF SAID LATCHES