US3561522A

US3561522A - Continuous casting apparatus including starter bar with quick disconnect sections

Info

Publication number: US3561522A
Application number: US734341A
Authority: US
Inventors: Leonard R Bosold
Original assignee: Republic Steel Corp
Current assignee: Republic Steel Corp
Priority date: 1968-06-04
Filing date: 1968-06-04
Publication date: 1971-02-09
Anticipated expiration: 1988-02-09
Also published as: DE1928522A1; GB1232357A; FR2011896A1

Abstract

A starter rod for continuous casting formed in a plurality of end connected sections where the sections are interconnected to form the starter rod by bayonet fittings which are of the quick assembly type. The connection fittings are constructed and arranged to provide a properly aligned rod of adequate strength and rigidity to comply with service requirements.

Description

United States Patent Inventor Appl. No.

Filed Patented Assignee Leonard R. Bosold Massillon, Ohio June 4, 1968 Feb. 9, 1971 Republic Steel Corporation an tom.

a corporation of New Jersey CONTINUOUS CASTING APPARATUS INCLUDING STARTER BAR WITH QUICK DISCONNECT SECTIONS 5 Claims, 12 Drawing Figs.

US. Cl 164/274, 287/53, 287/103 Int. Cl. 822d 11/08 Field of Search 164/82, 89,

Primary Examiner-Charles W. Lanham. Assistant ExaminerR. Spencer Annear Att0rneys-Robert P. Wright and Joseph W. Malleck ABSTRACT: A starter rod for continuous casting formed in a plurality of end connected sections where the sections are interconnected to form the starter rod by bayonet fittings which are of the quick assembly type. The connection fittings are constructed and arranged to provide a properly aligned rod of adequate strength and rigidity to comply with service requirements.

PA TENTED FEB 91 11 3.661.522

SHEET 1 BF 6 INVENTOR. Leonard R. Bosold C ATTZ RNEY I PATENTED FEB 9 I971 SHEET 3 BF 6 PATENTEU FEB 9 mn sum 5 OF 6 PATENTEU FEB 9m] 3561 522 SHEET 6 OF 6 CONTINUOUS CASTING APPARATUS INCLUDING STARTER BAR WITH QUICK DISCONNECT SECTIONS A STARTER ROD FOR CONTINUOUS CASTING 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 In operation, molten metal is delivered to the open upper end of the mold and an embryo casting is withdrawn from the lower end of the mold.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 casting. g 7

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 procedureor 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 discharged 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 1 provide a starter rod which may be readily assembled for starting use in a continuous casting operation, and may be readily disconnected in sections during the withdrawal of the rod from the continuous casting mold. With the structure of the invention, the starter rod may be used in conjunction with the usual starter heads, and with slight modifications the starter rod may be used in the continuous casting of substantially any transverse configuration of cast product. The sectionsare interconnected in end-to-end relation by connection elements formed in complementary portions or halves with a rotatable shaft journaled in one half selectively engaging by rotation a portion of the other half.

Of the drawings:

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

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 ofFIG. 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 8-8 of FIG. 7;

FIG. 9 is a section taken on line 99 of FIG. 8;

FIG. 10 is an enlarged section of a modified detachable connector of the starter rod;

FIG. 11 is a section taken on line l1-l1 of FIG. 10; and

FIG. 12 is a section taken on line 12-12 of FIG. 11.

As shown in FIG. I 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 l2 and is passed downwardly therefrom to an after-cooling 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 I 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 sufficient 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. Pat. No. 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 conveyor 20.

Prior to initiating the continuous casting operation it is necessary to position a dummy o'r starter head 25 in the bottom of the mold 12 (see FIGS. 2 and 3). The head 25 is sup ported 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 reassembled 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 inches by 8%inches. In such a mold the starter head 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 flat 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 suriaces 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 sidewall surfaces 30. The wall surfaces may be slightly inclined inwardly or outwardly without seriously affecting the casting keying function ofthe 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 con trolled rateby 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 removalof 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 rodlike segments or sections 50 which are ar-,

ranged for successive disassemblyand removal when each section is drawn below the withdrawal rollsl4 shown in FlG..l. As shown specifically in FIGS. 4 and 5 the upper end of the starter rod, to the left in the FIGS. includes a tapered segment 51 which is attached by bolt 39 to the upper end ofthe started 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 attachedby the bolt 39 the assembly is,- lowered until the head is positioned with respect to the mold.

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 thatthe length of the starter assembly must be sufficiently long to extend from the mold 12 through the withdrawal rolls 14 sothatas the con-. tinuous casting process is begun, the initially frozen,continuous casting which is keyed intothe 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 elementsSS is formed as a two-part structure which is held together by means of a rotatable shaft or rod 56 to provide a bayonet-typejoint. The opposite endsof'the ele-. ments 55 are each provided with a

tang

57 and 58 which extends outwardly vfrom the

end plates

60 and 61 respectively, with such tangs having

transverse openings

62 and 62 respectively and connectedby means of pins or bolts 63, to the corresponding end portions ofthe 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 portionA'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 transverselyarranged machined opening 67 in-register with mating holes drilled in the sidewalls of the lower portion. A to receive a sleeve or bushing and pin 68; Whenthe pin is. installed, the block 64 is rigidly connected within the lower.

portion A of the connecting element.

An upwardly extending cap, element 70projects into a recess 74formed in the upper portion B ofthe element 55 and is provided with a downwardly extendingstud 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 sidewalls of I 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 from the position shown in FIG. 7 the lower portion A of the con-. necting element together with the block 64 and cap element 70 may be withdrawn from the upper portion B.

While the connector element 55 mustprovide 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 intoblock 64, the center line of the machined slot 75 is 90 to the center line 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 83. 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.

While the starter rod shown in FIGS. 4 through 9 is applied in a continuous casting mold having a generally square transverse cross section, a starter rod of the same general construction can also be applied in a mold of elongated rectangular cross section, as when continuously casting a slab. In the latter circumstances the transverse cross section of the starter rod would also be of elongated rectangular configuration and formed of detachable sections joined by connector elements such as shown in FIGS. to 20, inclusive.

As shown in the drawings, the connector element 90 of FIGS. 10 to 12 is formed in two-parts held together by a rotatable shaft or rod 91 to provide a bayonet-type joint. Aside from the different cross-sectional shape the starter bar for a slab mold is similar to the parts described in connection with FIGS. 7, 8 and 9. Thus the similar parts shown in FIGS. 10, 11 .and 12 are identified by the same numbers with an additional digit added thereto.

The shaft '91 is elongated to extend through the major dimension of the connector element 90 and is rotatable to engage and disengage the element as hereinbefore described. To insure proper alignment of the assembled parts and to provide suitable support, the part 1A is provided with a flat surface 93 normal to the axis of the starter rod, where the surface is transversely grooved 94 on opposite sides of the vertical center line of the element. The part 18 is tapered on the external portions 95 and provided with projections 96 on its matching surface intended to fit into the grooves of the part 1A. Thus, when assembled the connector parts will engage for proper locking attachment by rotation of the shaft 91.

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

It will be noted the connecting elements 55 and are constructed with an axial or longitudinal center line common with the longitudinal axis of the starter rod and that the element parts are symmetrically arranged about the center line. Moreover the central axis of each

shaft

56 or 91 transversely intersects the longitudinal axis of the connecting element. Such an arrangement advantageously provides in-line stresses on the assembly during use regardless of the direction of force applied in controlling movement of the casting from the mold 12.

I claim:

1. Apparatus for continuous casting comprising a continuous casting mold having an open ended cavity therein, means for delivering molten metal to the cavity of said mold,

withdrawal meansfor withdrawing a castin from said mold, an elongated starter rod of sufficzlent lengt to extend from said withdrawal means to said mold, a head section detachably secured to an end of said starter rod and having a transverse configuration slightly smaller than and substantially corresponding with the casting mold cavity, said starter rod being characterized by a plurality of elongated sections, each section being end connected with an adjoining section by a connecting element, each connecting element being formed in complementary hollow portions with each attached to an adjoining starter rod section, and a. rotatable shaft journaled transversely in one of said portions for rotation into and out of locking engagement with a cooperating member pivotably mounted in the other of said portion.

2. Apparatus according to claim 1 wherein walls of complementary portions of each connecting element define facing centrally positioned recesses, said shaft being axially fixed in and journaled for rotation in the walls of one of said portions to project transversely across the recess in said one portion, and a member resiliently positioned in the recess of said other portion to extend in engaging relationship with said shaft when said portions are arranged in facing positions.

3. Apparatus according to claim 2 wherein said member extending beyond the other portion of said connecting element loosely fits into the recess of said one portion for centering purposes during assembly.

4. Apparatus according to claim 1 wherein the facing surfaces of said complementary portions include flat portions arranged transversely of the axis of said starter rod.

5. Apparatus according to claim 6 wherein the facing surface of one portion is provided with a groove on opposite sides of the axial center line of the element, the other portion is provided with correspondingly positioned projections engaging said grooves when the complementary portions are assembled, and the facing surface of the other portion is tapered outwardly of the projections.

Claims

1. Apparatus for continuous casting comprising a continuous casting mold having an open ended cavity therein, means for delivering molten metal to the cavity of said mold, withdrawal means for withdrawing a casting from said mold, an elongated starter rod of sufficient length to extend from said withdrawal means to said mold, a head section detachably secured to an end of said starter rod and having a transverse configuration slightly smaller than and substantially corresponding with the casting mold cavity, said starter rod being characterized by a plurality of elongated sections, each section being end connected with an adjoining section by a connecting element, each connecting element being formed in complementary hollow portions with each attached to an adjoining starter rod section, and a rotatable shaft journaled transversely in one of said portions for rotation into and out of locking engagement with a cooperating member pivotably mounted in the other of said portion.