US3503437A

US3503437A - Continuous casting starter head

Info

Publication number: US3503437A
Application number: US692341A
Authority: US
Inventors: William G Wilson
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1967-12-21
Filing date: 1967-12-21
Publication date: 1970-03-31
Anticipated expiration: 1987-03-31
Also published as: GB1216220A; DE6811890U; FR1595139A

Description

4 Sheets-Sheet 1 Filed Dec. 21, 1967 INVENTOR. William G. Wilson ATTORNEY March 31, 1970 I w, w so 3,503,437

CONTINUOUSLCASTING STARTER HEAD Filed Dec. 21, 1967 4 Sheets-Sheet 2 March 31, 1970 w. G. WILSON 3,503,437

CONTINUOUS CASTING STARTER HEAD Filed Dec. 21, 1967 4 Sheets-Sheet 3 on 5 mm mm on mm mm on m .u\ i H Luv m \s m n} M w Q Q a 0L H. H H mm mo #0 1E March 31, 1970 w. w| so 3,503,437

CONTINUOUS CASTING STARTER HEAD Filed Dec. 21, 1967 4 Sheets-Sheet 4 a l "T 56 I" K W I Z 64 72 i 68 United States Patent 3,503,437 CONTINUOUS CASTING STARTER HEAD William G. Wilson, Beaver Falls, Pa., assiguor to The Bahcock & Wilcox Company, New York, N.Y., a corporation of New Jersey Filed Dec. 21, 1967, Ser. No. 692,341 Int. Cl. B22d 11/08 US. Cl. 164274 6 Claims ABSTRACT OF THE DISCLOSURE A starter head for continuous casting having a recess in one end thereof and a tang extending from the opposite end of the starter head for attachment to a starter bar. The recess having sockets in the opposite side walls thereof to receive a bar forming a heat sink for attachment of initially frozen metal of the continuous casting thereto. At least one wall of the starter head recess containing a socket is transversely removable for insertion of the bar and removal of the casting discard after use in the continuous casting operation.

This invention relates to the continuous casting of metals, and more particularly to an improvement in the dummy or starter head and rod assembly used to initiate the casting of metals in an open ended continuous casting mold.

In the continuous casting of metals the mold is usually of the upright fluid cooled type, open at both ends. In operation, molten metal is delivered to the open upper end of the mold and an embryo casting is Withdrawn from the lower end of the mold. Since the mold is bottomless, it becomes necessary to insert a starter head or plug to temporarily close the bottom of the mold until the newly introduced molten metal has solidified sufficiently to permit controlled withdrawal of the starter head and the attached casting from the mold. After the continuous casting procedure has been started, the starter rod and the head will be removed for reuse in initiating a succeeding period of continuous castmg.

Many different constructions have been utilized to provide a suitable head and starter rod structure for initiating the casting process. The type of starter rod assembly is largely dependent upon the type of continuous casting procedure utilized, i.e. Whether the starter rod must follow a curved configuration such as in the bow mold casting procedure or whether the continuous casting unit is arranged for vertical operation. However, in all procedures the initially cast metal forming the bottom of the continuous casting must be attached to the starter head so that the starter rod will be effective in initiating the withdrawal of the casting from the mold. This also necessitates the separation of a minor portion of the initially cast metal with the head of the starter rod from the casting when the use of the starter assembly is discontinued. Ordinarily the short length of metal casting attached to the head will be discarded and at least some part of the dummy head as initially installed must also be discarded with the discard portion of the casting.

In the present invention I provide a starter head and a joined starter rod which may be readily disconnected in sections during the gradual Withdrawal of the starter rod from the mold. The starter head also must be detachable from the starter rod in such a manner as to permit removal of the starter head and the casting discarded from I the rod assembly. With the structure of the present invention the starter head is quickly and easily parted from the discard portion of the casting and prepared for subsequent successive use in initiating the continuous cast- 3,503,437 Patented Mar. 31, 1970 ing process with a minimum of materials discard. The starter head of the invention is particularly characterized by the construction of its mating parts which are designed to hold scrap metal pieces which later may be economically discarded along with the discard portion of the casting. The starter head itself is easily and conveniently re assembled utilizing heat absorber materials which form the key for connecting the head with the casting in each successive use of the apparatus.

Of the drawings:

FIG. 1 is an elevation of a continuous casting unit incorporating the present invention; 4

FIG. 2 is an enlarged section of the starter head or plug showing the details of construction of the detachable portions;

FIG. 3 is a section taken on line 3-3 of FIG. 2;

FIG. 4 is a longitudinal section view of the starter rod of the present invention;

FIG. 5 is a section taken on line 5-5 of FIG. 4;

FIG. 6 is an assembly, in section, of the dummy head installed at the end of the starter rod;

FIG. 7 is an enlarged section view of a detachable connector shown in FIGS. 4 and 5;

FIG. 8 is a section taken on line 88 of FIG. 7; and

FIG. 9 is a section taken on line 9-9 of FIG. 8.

As shown in FIG. 1 the continuous casting unit is of the vertical type and includes a molten metal pouring apparatus such as a ladle 10 and tundish 11 for the delivery of molten metal to the continuous casting mold 12. The molten metal is solidified, at least in part, within the mold 12 and is passed downwardly therefrom to an aftercooling section 13. Leaving the section 13 the casting is passed through a set of withdrawal rolls 14 which regulate the rate of movement of the casting 15 from the mold. The casting is solidified before or shortly after passing through the withdrawal rolls 14, and in leaving the rolls 14 will be cut to length for ease of handling by an oxygen lance 16 or the like. As shown in FIG. 1 the cut lengths of castings or ingots 17 will be removed by a handling mechanism 18 which lowers the ingot to a conveyor 20, for delivery to a place of storage or for further processing.

As shown, the ladle 10 is of the bottom pour type and is supplied with molten metal from one or more furnaces (not shown), transported to a pouring location by an overhead crane (not shown) or other similar device, and mounted for effective positioning relative to the tundish 11. When the ladle is properly positioned, molten metal is discharged therefrom through a nozzle at a controlled rate for delivery of the molten metal to the tundish. The tundish is usually constructed and arranged for bottom pouring and provides for a maximum elimination of slag before the molten metal is delivered to the casting mold 12.

The embryo casting 15 leaving the lower end of the mold '12 will have a frozen metal skin of sufiicient thickness to confine the molten metal core therein as it leaves the discharge end of the mold. The casting then passes through the after-cooling section 13 where it is further cooled by streams of water directed against its Walls. Additionally the casting is supported by a mechanism intended to inhibit swelling of the casting during the cooling process. Such an after-cooling and support section for continuous casting is shown, for example, in U.S. Patent 2,770,021.

In the embodiment shown, the casting 15 leaving the withdrawal rolls 14 is cut to preferred lengths by means of an oxygen torch 16. Since the casting is moving downwardly during the casting operation it is necessary for the torch to move with the casting while cutting to the desired length. The ingot 17 cut to desired length is engaged by a handling mechanism 18 which is arranged to transport the ingot 17 from an initial vertical receiving position to a horizontal discharging position. The ingot 17 is then removed from the casting unit by the roller con- 'veyor:20.

Prior to initiating the continuous casting operation it is necessary to position a dummy or starter head 25 in the bottom of the mold 12 (see FIGS. 2 and 3). The head 25 is supported upon a sectional starter rod 26 which extends upwardly from the pinch rolls 14 to a preferred position of the head within the lower portion of the mold 12. When the casting operation is starting the molten metal poured into the mold freezes about the keying structure of the starter head 25 thereby forming an effective stopper or plug. When the proper molten metal level in the continuous casting mold 12 has been attained, Withdrawal of the starter rod 26 with the initially frozen casting metal secured to the head may be initiated. As each jointed section of the starter rod 26 (as hereinafter described) leaves the withdrawal rolls 14, such section can be removed until the head 25 itself passes through the rolls. The torch 16 will then be actuated to cut the pendant casting at a position upwardly adjacent the head 25 so that the head and the frozen metal discard attached thereto may be removed from the last section of the starter rod. Thereafter the continuous casting operation continues in a normal manner until all of the molten metal has been processed.

If the continuous casting unit is being operated with closely spaced individual pours the dummy head 25 may be disengaged from the discard metal of the casting while the normal continuous casting procedure is being followed. With the removal of the discard and the expendable portions of the dummy head, the dummy head may then be re-assembled as hereinafter described to be ready to initiate the next succeeding molten metal pour.

In the illustrated embodiment of the invention shown in FIGS. 2 and 3 the starter head 25 is shown as constructed and arranged for use in a continuous casting mold '12 of rectangular horizontal cross-section. In the specific example the mold cross-section is approximately by 8%". In such a mold the starter head 25 is constructed to loosely fit in the lower portion of the mold 12 when installed for initial operation of the continuous casting unit. Before molten metal is supplied to the continuous casting mold '12 the clearance space between the periphery of the head and the mold wall may be packed with asbestos rope or other sealing material.

The head 25 is formed with a recess 32 in the upper surface thereof to receive the molten metal initially supplied to the mold. As hereinafter described in greater detail, the recess is provided with disposable metallic bars supported in opposing walls of the recess to key into and become an integral part of the lower end of the casting when the molten metal solidifies.

As shown in FIGS. 2 and 3, the upper end portion of the head 25 is constructed in two parts. One of the parts 27 is formed to provide walls for generally one-half of the molten metal receiving recess 32 and is further provided with a lower extension which forms the tang 28 for attachment to the starter rod 26 as by a bolt 39. The mating part 31 of the head 25 is constructed as a transversely removable portion of the upper end of the head forming the walls of the remaining portion of the recess 32. The part 31 has a fiat bottom 34 slidably supported on a base 35 constructed as a projecting shoulder of the part 27. To insure a proper connection with the matching surf-aces of

parts

27 and 31, a tongue 33 of part 31 projects into a groove 36 correspondingly formed in the part 27. When assembled, the

parts

27 and 31 form a head 25 symmetrical about a longitudinal axis and having the centrally disposed recess 32 open at the top to receive molten metal. As shown in FIGS. 2 and 3, the recess is generally rectangular in cross-section and is bounded by generally upright side wall surfaces 30. The wall surfaces 30 may be slightly inclined inwardly or outwardly without seriously affecting the casting keying function of the head 25. The parting line of the mating portions of the dummy head is indicated by the numeral 37. When assembled, the two portions are held together by a pair of horizontally spaced threaded bolts 38. Opposite walls of the head 25 are provided with

sockets

40 and 41 to accommodate loosely fitted bars 42 which are inserted before assembly of the two parts of the head. Thus when the two parts are bolted together the bars have their opposite ends engaged in the sockets to form a keying arrangement and heat sink about which molten metal freezes to permit withdrawal of the embryo casting from the continuous casting mold. In addition to the bars positioned in the recess 32 of the head, other metallic bars 43 are positioned transversely across and resting on the upper surface of the bars 42 to provide metal for an additional heat sink and to aid in providing the attachment between the initially formed frozen metal of the continuous casting and the head. As a further protection to the head assembly a flat plate 44 is inserted in the bottom of the recess 32, resting on the upper surface of the mating portions of the dummy head. Thus when molten metal is delivered to the mold 12 initial freezing of the molten metal will occur around the

bars

42 and 43 but not between the mating portions of the head. The cover plate 44 will also serve as protection for the bottom surface of the recess 32.

With the molten metal freezing about the

bars

42 and 43 the casting as it freezes may be withdrawn from the mold at a controlled rate by operation of the withdrawal rolls 14. When the head 25 with the newly cast metal has been withdrawn below the rolls 14 the initially frozen portion may be cut from the casting and the head 25 with the end portion of the starter rod may be removed from the casting apparatus. The head may then be disconnected from the starter rod 26 by removal of the bolt 39. With the head 25 and the frozen metal discard end of the continuous casting forming a single unit the head may be separated along its parting line 37 for removal of the casting discard along with the

expendable parts

42, 43 and 44. It will be understood that these parts will have generally lost their separate identity in fusing into the casting discard. The

head parts

27 and 31 may be separated by hydraulic or mechanical apparatus provided with pairs of prongs which engage

sockets

45 and 46 formed in the

respective parts

27 and 31 for this specific purpose.

The starter rod 26 shown in FIGS. 4 and 5 includes a series of connected rod-like segments or sections 50 which are arranged for successive disassembly and removal when each section is drawn below the withdrawal rolls 14 shown in FIG. 1. As shown specifically in FIGS. 4 and 5 the upper end of the starter rod, to the left in the figures, includes a tapered segment 51 which is attached by bolt 39 to the upper end of the starter rod 26. When preparing a continuous casting unit for casting service, the assembled rod is threaded up through the rolls 14 with the upper end segment 51 extended through the mold 12. The tapered segment is then removed from the starter rod 26 and the head 25 installed in its place, as is shown in FIG. 6. With the head 25 attached by the bolt 39 the assembly is lowered until the head is positioned with respect to the mold 12 as shown in FIGS. 2 and 3.

The starter rod assembly is made up of a series of sections 50 which may be of any selected length with each of the sections connected by means of a quickly detachable connector element 55, hereinafter described, to an adjacent section. The connecting elements 55 between adjacent sections are shown in detail in FIGS. 7, 8 and 9.

The sections 50 each include a spacer element 54 fabricated of steel plates formed in the general configuration of the cavity of the mold 12, and which is suitably reinforced to withstand the operating load on the assembled sections. The spacer elements 54 may be of any desirable length so that the assembled starter rod 26, including the spacer elements 54 and the connecting elements 55, may form a unit of the desired length. It is, of course, understood that the length of the starter assembly must be sufficiently long to extend from the mold 12 through the withdrawal rolls 14 so that as the continuous casting process is begun, the initially frozen continuous casting which is keyed into the starter head 25, and the starter rod 26 may be gradually Withdrawn thereby initiating the continuous casting operation.

Referring to FIGS. 7, 8 and 9 it will be noted that each of the connection elements is formed as a two-part structure which is held together by means of a rotatable shaft or rod 56 to provide a bayonet type joint. The opposite ends of the elements 55 are each provided with a

tang

57 and 58 which extends outwardly from the

end plates

60 and 61 respectively, with such tangs having transverse openings 62 and 62' respectively and connected by means of pins or bolts 63, to the corresponding end portions of the spacer elements 54.

As illustrated, the mating portions of the connecting element are constructed of welded plates formed to include open ended recesses which accommodate the elements of the bayonet type joint. As shown in FIG. 7, the lower portion A of the element is provided with a block 64 which fits into the lower recess 65 and is provided with springs 66 interposed between the block 64 and the end plate 60. The block 64 is provided with a transversely arranged machined opening 67 in register with mating holes drilled in the side walls of the lower portion A to receive a sleeve or bushing and pin 68. When the pin is installed, the block 64 is rigidly connected within the lower portion A of the connecting element.

An upwardly extending cap element 70 projects into a recess 74 formed in the upper portion B of the element 55 and is provided with a downwardly extending stud 72 which is threaded into a corresponding aperture 73 in the block 64. The cap element 70 has a transversely extending machined slot 75 of circular cross section having an open upper face 76. The rotatable shaft or rod 56 is journaled in the side walls of the upper portion B of the connecting element and projects through the slot 75 of the cap 70. The pin 56 is provided with parallel flattened faces 77 so that when it is rotated 90 from the position shown in FIG. 7 the lower portion A of the connecting element together with the block 64 and cap element 70 may be withdrawn from the upper portion B.

While the connector element 55 must provide a strong, stable connection between the sections of the starter rod, the bayonet type joint must also be constructed with sufficient flexibility to permit assembly and disassembly during all reasonable conditions of operation. The gap at junction line 80 and the springs 66 will give ample correction for misalignment of the dummy sections when connecting. Shim plate 81 should be accurately sized so that when cap element 70 is screwed into block 64, the centerline of the machined slot 75 is 90 to the centerline of pin 68, and the shim plate 81 is held tightly between cap element 70 and block 64. The base of the cap 70 is provided with a locking finger 82 attached to a side of the block 64 to lock the parts in the preferred relationship.

The shaft 56 is provided with an indentation or socket 83 at opposite ends into which a turning tool, such as a socket wrench, may be inserted for engaging and disengaging the bayonet type joint. The shaft 56 is completely enclosed within the bore 75 by end plates 84 having enlarged central openings 85 see FIG. 9 therethrough in alignment with each socket 833. The opposite peripheral end portions of the shaft are increased in diameter to accommodate thrust springs 86 which bear on the end plates 84 and tend to center the shaft 56 so that the flats 77 thereon are 90 from alignment with the open slot 76 in the upper face of cap 70 when the wrench is removed and no torque is applied to shaft 56.

The construction described permits effective use of the starter rod 26 under all conditions of operation, and facilitates ready use of the bayonet type joints between sections for assembly and disassembly of the starter rod.

What is claimed is:

1. Apparatus for continuous casting comprising a continuous casting mold, means for delivering molten metal to said mold, an elongated starter bar, a head section detachably connected with an end of said starter bar, said head section having an exterior configuration substantially conforming with the interior of said casing molding and insertable therein and having a plurality of separable portions, said starter bar head section being characterized by walls defining a recess in the upper end thereof to receive the initial molten metal delivered to said mold, a metallic bar positioned intermediate the depth of said recess and extending transversely across said recess, said bar being generally normal to the axis of said starter rod, and means for transversely detaching at least a portion of said head section including a wall portion of said recess supporting one end of said bar from the remaining portion of said head whereby the metallic bar and the cast metal solidified therearound can be detached from said head.

2. Apparatus for continuous casting according to claim 1 wherein the walls defining said recess are provided with sockets formed in opposite sides thereof to loosely accommodate said bar.

3. Apparatus for continuous casting according to claim 1 wherein a metal plate is positioned across the bottom of said recess to protect said head from molten metal depositing thereon.

4. Apparatus for continuous casting according to claim 2 wherein the transversely detachable portion of said head includes approximately one-half the exposed portion of said recess.

5. Apparatus for continuous casting according to claim 1 wherein a plurality of metal bars are transversely spaced across said recess, and other metallic elements are laid on said bars to form a heat sink for solidifying the molten metal delivered thereto.

6. A starter head for continuous casting comprising a head portion having a central recess in one surface and a tang extending from the opposite end thereof, means forming countersunk sockets paired in opposite side walls of said recess and spaced intermediate the open top and closed bottom of the recess, a bar extending across said recess between said sockets, said head having an upper portion having a plurality of separable elements and bottom portion transversely removably connected thereto, said upper portion and bottom portion including at least one wall of said recess containing one of an opposite pair of said sockets.

References Cited UNITED STATES PATENTS 3,266,104 8/1966 Foldessy et a1 164-274 3,333,627 8/1967 Forster l64282 3,448,789 6/1969 Gallucci 164-274 FOREIGN PATENTS 929,478 6/1963 Great Britain.

I. SPENCER OVERHOLSER, Primary Examiner R. S. ANNEAR, Assistant Examiner