US3602290A

US3602290A - Dummy bar for continuous casting

Info

Publication number: US3602290A
Application number: US754808A
Authority: US
Inventors: George E Schmidt; Lyle J Johnson; Willi Simons; Walter Hess; Josef Bard
Original assignee: Schloemann AG; MCLOUTH STEEL CORP
Current assignee: Schloemann AG; MCLOUTH STEEL CORP
Priority date: 1968-08-23
Filing date: 1968-08-23
Publication date: 1971-08-31
Anticipated expiration: 1988-08-31
Also published as: DE1942596B2; GB1251875A; AT307646B; DE1942596A1; SE406162B; FR2017018A1; BE737771A; FR2017018B1

Abstract

In a dummy bar for temporarily plugging an end of an open-ended continuous-casting mold at the start of casting, means for removably connecting the head of the dummy bar to a casting being formed in the mold comprises a notch in one side of the dummy bar head. The notch has a deeply indented portion and a less deeply indented portion between the deeply indented portion and the end of the head that is within the mold when the head is inserted in the mold to plug it. Thus, with the head plugging the mold, the notch and adjacent wall of the mold form a hooklike cavity in which molten metal poured into the mold for the casting flows and solidifies for making the connection. Then when the dummy bar and the casting attached thereto are withdrawn from the mold, they are separated by moving the dummy bar sideways in a direction to unhook them.

Description

United States Patent 2,176,990 10/1939 Crampton DUMMY BAR FOR CONTINUOUS CASTING 7 Claims, 5 Drawing Figs.

[18. Cl Int.

Field of Search mm Cited UNITED sures PATENTS Primary Examiner-R. Spencer Annear Attorney-Sandoe, Neill, Schottler and 'Wikstrom ABSTRACT: In a dummy bar for temporarily plugging an end of an open-ended continuous-casting mold at the start of casting, means for removably connecting the head of the dummy bar to a casting being formed in the mold comprises a notch in one side of the dummy bar head. The notch has a deeply indented portion and a less deeply indented portion between the deeply indented portion and the end of the head that is within the mold when the head is inserted in the mold to plug it. Thus, with the head plugging the mold, the notch and adjacent wall of the mold form a hooklike cavity in which molten metal poured into the mold for the casting flows and solidifies for making the connection. Then when the dummy bar and the casting attached thereto are withdrawn from the mold, they are separated by moving the dummy bar sideways in a direction to unhook them.

DUMMY BAR FOR CONTINUOUS CASTING The present invention relates to dummy bars which are used to removably plug ends of open ended mold cavities in the continuous casting of metal, such as steel. The invention relates particularly to a dummy bar head which provides improved means for temporarily connecting the lead end of a continuous casting to a dummy bar at the start of casting.

In continuous casting, molten metal is poured in the top of an open-ended mold cavity of a chill mold that cools and solidifies the periphery of the metal therein to form a casting which is withdrawn from the bottom or exit end of the mold cavity.

At the start of casting, the exit end of the mold cavity is temporarily plugged by a dummy bar until sufiicient molten metal accumulates in the mold for the casting to form. Connecting means is provided at the end of the dummy bar, which is within the mold cavity, for connecting the dummy bar to the casting being formed. When sufficient casting is formed in the mold cavity, it is started out of the mold cavity by withdrawing the dummy bar by suitable withdrawal mechanism which engages the dummy bar. Thereafter, the dummy bar is disconnected from the casting and prepared for reuse. The formation and withdrawal of a continuous casting is accomplished by continuing to pour molten metal in the top end of the mold cavity as the casting is withdrawn from the bottom end.

In known continuous casting apparatus, means for connecting the dummy bar to the casting customarily consists of a projection from the dummy bar head around which the metal solidifies. The projecting portion of the head then becomes firmly embedded in the casting.

One known arrangement consists in having the projection provided by a section of rail which has a base flange keyed in a groove across the dummy bar head. The dummy bar is subsequently separated from the casting by moving the casting and dummy bar laterally apart to slide the base flange out of the groove. The section of rail remains embedded in the casting and must be replaced by a new section to prepare the dummy bar for reuse, which takes time and wastes material. In addition, this arrangement sometimes causes difficulty because the molten metal tends to become welded to the surface of the dummy bar head, as well as to the rail, so that extra time and effort is required to effect the separation. Also, the force that may have to be applied or the method that may have to be employed for the separation may damage the dummy bar.

In a known type of dummy bar the head, which has a removable section of rail or other element to become embedded in the casting, is separably connected to the body of the dummy bar by a hooklike joint or other joint which is disconnectable by bending or shifting the dummy bar sideways relative to the casting. With this type of arrangement, however, the head remains connected to the casting. It is therefore necessary to sever the head from the casting. Then, after the head has cooled, the connecting element, such as a section of rail, is removed from the head, which may then be fitted with a new connecting element and reattached to the body of the dummy bar for reuse. The head, of course, cannot be severed from the casting until the casting has come to rest at the end of a casting run. The of the dummy bar from its head and the head from the casting thus requires three individual steps so that the manner of separating the dummy for reuse is complicated and time consuming.

It is an object of the present invention to provide a dummy bar head having improved connecting means such that the dummy bar, with its head attached, can be separated from the casting during the casting run while the lead end of the casting is moving along a path from the mold, and such that the dummy bar, and its head, are in condition for reuse immediately on separation from the casting, without reassembling or reconditioning.

In accordance with the present invention, means for removably connecting the dummy bar to a continuous casting is provided by a notch in the side of the portion of the dummy bar head that is received in one end of the mold cavity. The

overall cross-sectional configuration and dimension of the dummy bar head and mold cavity are similar in order for the head to plug the cavity when received therein. The notch has a deeply indented portion and a less deeply indented portion whichis between the deeply indented portion and the end of the dummy bar head that is received in the mold cavity. The notch thus forms a hooklike cavity with the adjacent wall of the mold cavity so that molten metal poured in the unplugged end of the mold cavity for the casting flows into the hooklike cavity and solidifies therein to make the connection by the interlocking hooks provided by the notch and the solidified metal When the dummy bar and the casting attached thereto are withdrawn from the mold cavity-by known withdrawal mechanism which engages the sides of the dummy bar and pulls the dummy bar and casting longitudinally from the mold cavity-they are subsequently disconnected by moving the dummy bar head sideways relative to the casting so that the said interlocking hooks disengage. This may be accomplished while the casting is moving along its path from the mold, and the dummy bar, which is then removed from the path of the casting, is ready for reuse.

Further objects, advantages, and features of the invention will be apparent from the following description of illustrative embodiments shown in the accompanying drawings in which:

FIG. 1 is a front view of a dummy bar head embodying the present invention:

FIG. 2 is a plan view of the dummy bar head of FIG. 1, showing it in operative position in the cavity of a continuous casting mold;

FIG. 3 in a plan view similar to FIG. 2, but illustrating an alternative form of a dummy bar head embodying the invention;

FIG. 4 is a cross-sectional view along the line 4-4 of FIG. 1; and

FIG. 5 is a cross-sectional view similar to FIG. 4, but illustrating alternative structure.

Referring to the drawings, a dummy bar head 10 embodying the present invention is adapted to be removably received in, and to plug, the bottom end of a mold cavity 11 of a continuous-casting mold 12. The cross-sectional configuration of the mold cavity 11 is illustrated as being rectangular, for casting steel slabs. Mold cavities and corresponding dummy bar heads of other configurations are, of course, used for casting other cross-sectional shapes, such as round, square, channel or I- beam, and it will be appreciated that the present invention is adapted for dummy bar heads of various cross-sectional configurations, the rectangular configuration being for illustrative purposes only.

As shown in FIGS. 1 and 4, the bottom portion of the dummy bar head 10 is provided with vertical slots 13 and horizontal bores 14 by which the dummy bar head is hinged to the body of a dummy bar (not shown) in a conventional manner. In a preferred form the hinged joint is such as to permit deflection only in one direction-for example, by pivotally connecting the dummy bar and the dummy bar head 10 by a pivot pin through the lower bore, and by utilizing a pin through the upper bore 14 as a stop pin to be engaged by the upper end of the body of the dummy bar for preventing pivotal movement in one direction.

The cross-sectional configuration of the lower part 10a of the dummy bar head 10 conforms to the cross-sectional configuration of the bottom end of the mold cavity 11 so as to plug this end of the cavity. The upper part 1011 of the dummy bar head 10, which extends up into the mold cavity 11, has a notch 15 in one side while its opposite side abuts the sidewall 16 of the mold cavity 11. The notch 15 has a relatively deeply indented portion 15a and a less deeply indented portion 15b between the deeply indented portion 15a and the upper end 17 of the dummy bar head, so that it has a hooklike vertical cross section and leaves a ledge 18 across its upper end. Thus, when the dummy bar head 10 is in the mold cavity 11, the notch 15 forms a hooklike cavity with the adjacent wall 19 of the mold cavity 11 so that molten metal poured into the upper end of the mold cavity for the casting flows down into the hooklike cavity and solidifies therein to connect the dummy bar head to the casting.

The deeply indented portion 15a of the notch 15 is defined by a bottom wall 20, upper and

lower end walls

21 and 22, and, in the embodiment illustrated in FIGS. 1 and 2, by opposite sidewalls 23. In the embodiment illustrated in FIGS. 1 and 2 the notch 15 is open only through one side of the dummy bar head. In the embodiment illustrated in FIG. 3 the notch 15 extends completely across one side of the dummy bar head so that the sides of the notch are open-to be blocked by the adjacent walls of the mold cavity when the dummy bar head is received therein.

In the embodiment illustrated in FIGS. 1 and 4 the bottom wall 20 of the deeply indented notch portion 15a is shown as being substantially parallel to the outer wall of the dummy bar head behind it, but this parallelism is not necessary. To facilitate the release of the casting from the dummy bar head, it is advantageous to have at least one of the

end walls

21 and 22 diverge outward from the bottom wall 20 with respect to a horizontal plane, indicated by line 24 in FIGS. 4 and 5, which is at right angles to the longitudinal axis of the dummy bar head (and of a casting attached thereto). In FIG. 4 the lower end wall 22 illustrates such divergence; the upper end wall 21 is shown substantially parallel to the aforesaid horizontal plane. To facilitate smooth release of the casting in a predetermined direction it is preferable to have the sidewalls 23 (FIG. 2) each diverge outward at the same angle, or, if the sidewalls 23 do not diverge, to have them parallel to each other. The sidewalls are also preferably flat except for their outer marginal edges which may advantageously be rounded.

The connection between the casting and the dummy bar head is also suitable stabilized by having at least one of the

end walls

21 and 22 inclined from its outer ends toward its central portion. The degree of inclination is approximately the same, and in the same direction, at opposite sides of the central portion, as illustrated by the inclination of upper end wall 21 in FIG. 1. In the form illustrated, the outer portions of the upper end wall 21 are inclined downward from the central portion so that the vertical cross section of the relatively deeply indented portion 150 of the notch is greater at the center. FIG. 5 illustrates a modification of the notch in which the upper end wall 21a is shown as being undercut to form a barb. This further assures a firm connection between the casting the dummy bar head until it is desired to separate them. The manner of effecting the separation is subsequently described in detail.

The upper end 17 of the dummy bar head may be horizontal, or it may be slanted, as shown, which reduces splashing as molten metal is poured into the mold cavity 11 and directs molten metal into the hooklike cavity formed by the notch 15. In addition, in a preferred form illustrated in FIG. 1, an opening 25 is provided through the central portion of the ledge 18, which is between the less deeply indented portion 15b of the notch 15, and the upper end 17 of the dummy bar head 10, so as to provide an opening from the upper end 17 directly through to the relatively deeply indented portion 150 of the notch. This opening 25 assists in centering a stream of molten metal being poured into the mold cavity 11 and reduces splashing. In addition, since the several walls defining the notch 15, and the hooklike cavity formed by it, are of different thicknesses, molten metal in different portions of said cavity solidifies at different rates and the resulting unequal contraction in different portions of the metal, which distorts that portion of the casting, might inhibit the separation of the casting from the notch 15. The provision of the opening 25 avoids this problem. The separation is further facilitated by having the lateral edges 26 of opening 25 diverge outward as shown.

Additional openings, for the same purpose as the opening 25, may be provided through the ledge 17 at other points along it. FIG. 3 illustrates another embodiment in which three openings 27 are provided through the ledge 17, one being at the central portion in the position occupied by the opening 25 in the embodiment shown in FIGS. 1 and 2. The

openings

25 and 27 also facilitate the complete filling of the hooklike cavity with the metal of the casting and provide reinforcing ribs in the portion of the casting between the portion in said cavity and the portion above the dummy bar head.

When dummy bar head 10 is in place in the bottom end of the mold cavity 11, the outside walls on three sides of the upper part 10b (the two short sides and the one long side in back of the notch 15) abut the walls of the mold cavity 11 and the infiltration of molten metal between the abutting wall surfaces is suitable prevented by sealing the cracks with packing, such as asbestos cord or the like. The placement of this packing is facilitated by beveling the upper marginal edges of the upper part 1012 of the dummy bar head as indicated by the beveled edge 28.

Repeated use of the dummy bar may cause the upper part 10b of the dummy bar head to wear to such an extent that it is unfit for further use, while the lower part 10a is still serviceable. Therefore, in order to be able to replace worn upper parts 10b so as not to have to scrap the complete head 10, the upper and lower parts 10b and are suitably separate elements detachably connected by appropriate means, such as a key and keyway connection illustrated at 29 in FIG. 4.

The most wear on the dummy bar head 10 occurs in the notch 15, and another means of extending the service life of the upper part 10b of the dummy bar head 10 is to provide the notch 15 with a replaceable lining, indicated at 30 in FIG. 5, which may be formed of sheets of a metal which has appropriate thermal conductivity and resistance to thermal shock best adapted to withstand the repeated heating and cooling to which the surfaces of the dummy bar head are subjected.

When molten metal poured into the mold cavity 11 for the casting has filled, and solidified in, the hooklike cavity formed by the notch 15, the dummy bar and the casting thereby attached to it are withdrawn from the mold cavity by known withdrawal mechanism which engages the dummy bar. From the mold cavity, the continuous casting is drawn through straightening mechanism and then conveyed to other mechanism for further processing.

At some point after the dummy bar head 10 has been drawn out of the mold cavity, and preferably after it has passed the withdrawal and straightening mechanism, it is separated from the casting by relative movement of the dummy bar head and casting apart at an angle to the longitudinal axes of the dummy bar head and casting. The angle is such that the hooklike portion of the casting formed by the notch 15 disengages therefrom. This relative movement may suitably be applied by moving or bending the dummy bar head 10 to the side while a portion of the casting following the dummy bar head is in the straightening mechanism which thus serves as a counterhold for the casting.

With a notch 15 having the cross-sectional configuration illustrated in FIG. 4, the separation is suitably affected by moving the dummy bar head relatively to the left at right angles to the direction of travel of the dummy bar and casting (which travel downwardly in the direction of their longitudinal axes). If the notch 15 is barbed as illustrated in FIG. 5, the resultant separating movement would be up and to the left at an oblique angle rather than at right angles to the direction of travel. This latter separating movement may be accomplished by applying a combination of forcesone at right angles to the direction of travel and one opposite to the direction of travel-so that the resultant applied force is up and to the left as aforesaid. The opposing force may be applied just before applying the force at right angles, or the withdrawal speed of the dummy bar may be reduced and this combination of forces then applied at one time. The relative motion of the dummy bar to accomplish the separation may be provided by the operation of a storage device for the dummy bar. Such a storage device is disclosed in U.S. Pat. No. 3,351,124.

The separation is assisted by the shrinkage of the portion of the casting within the notch as the casting cools. The separation may also be facilitated by applying release coatings of graphite or other material to the surfaces of the notch 15 or by covering these surfaces with layers of asbestos.

When the separation is complete the dummy bar is removed from the path of movement of the casting by suitable means, such as the above-mentioned storage device. The casting is then free to continue on its way and the dummy bar is in condition for use for a subsequent casting run.

What we claim is:

l. A dummy bar having a head adapted for removably attaching the dummy bar to the end of a continuous metal casting formed in the open-ended mold cavity, said head comprising a lower part and an upper part, the lower part of said head having a cross-sectional configuration and dimension to removably fit in and plug an end of the mold cavity, the upper part of said head having a notch in one side, at least a portion of the wall of the head at the opposite side from the notch being adapted to abut the adjacent portion of the sidewall of the mold cavity when the head is in said end of the mold cavity for preventing molten metal in the mold cavity from penetrating between said adjacent wall portions of the head and mold cavity, said notch having a relatively deeply indented portion and a less deeply indented portion between the deeply indented portion and the end of the head that is within the mold cavity when the head is in said end thereof for forming a hooklike cavity into which molten metal poured into the mold cavity flows and solidifies for attaching the upper part of the dummy bar head to the casting thereby formed, the end wall of the deeply indented portion of the notch, which is adjacent to the bottom wall of the less deeply indented portion of the notch, being undercut to form a barb, the upper part of the dummy bar head and the casting being adapted to be separated subsequently by relative lateral movement away from each other with respect to their longitudinal axis.

2. A dummy bar having a head adapted for removably attaching the dummy bar to the end of a continuous metal casting formed in the open ended mold cavity, said head comprising a lower part and an upper part, the lower part of said head having a cross-sectional configuration and dimension to removably fit in and plug an end of the mold cavity, the upper part of said head having a notch in one side, at least a portion of the wall of the head at the opposite side from the notch being adapted to abut the adjacent portion of the sidewall of the mold cavity when the head is in said end of the mold cavity for preventing molten metal in the mold cavity from penetrating between said adjacent wall portions of the head and mold cavity, said notch having a relatively deeply indented portion and a less deeply indented portion between the deeply indented portion and the end of the head that is within the mold cavity when the head is in said end thereof for forming a hooklike cavity into which molten metal poured into the mold cavity flows and solidifies for attaching the upper part of the dummy bar head to the casting thereby formed, the two portions of at least one of the end walls of the deeply indented portion of the notch being inclined in the same direction respectively outwardly from the central portion of said end wall to opposite sides of the notch, the upper part of the dummy bar head and the casting being adapted to be separated subsequently by relative lateral movement away from each other with respect to their longitudinal axis.

3. The dummy bar of claim 2 in which the bottom wall of the deeply indented portion of the notch is approximately parallel to the sidewall of the dummy bar head behind it, and in which the sidewalls and at least one of the end walls of the deeply indented portion of the notch diverge from the bottom wall thereof,

4. A dummy bar having a head adapted for removably attaching the dummy bar to the end of a continuous metal casting formed in the open-ended mold cavity, said head comprising a lower part and an upper part, the lower part of said head having a cross-sectional configuration and dimension to removably fit in and plug an end of the mold cavity, the upper part of said head having a notch in one side, at least a portion of the wall of the head at the opposite side from the notch being adapted to abut the adjacent portion of the sidewall of the mold cavity when the head is in said end of the mold cavity for preventing molten metal in the mold cavity from penetrating between said adjacent wall portions of the head and mold cavity, said notch having a relatively deeply indented portion and a less deeply indented portion between the deeply indented portion and the end of the head that is within the mold cavity when the head is in said end thereof for forming a hooklike cavity into which molten metal poured into the mold cavity flows and solidifies for attaching the upper part of the dummy bar head to the casting thereby formed, the less deeply indented portion of the notch having at least one opening therethrough between the deeply indented portion and the adjacent end of the head, the upper part of the dummy bar head and the casting being adapted to be separated subsequently by relative lateral movement away from each other with respect to their longitudinal axis.

5. The dummy bar of claim 4 in which said notch extends completely across one side of the dummy bar head so that the sides of the notch are open at opposite sides of the dummy bar head.

6. The dummy bar of claim 5 in which at least one of the end walls of the deeply indented portion of the notch diverges from the bottom wall thereof.

7. The dummy bar of claim 2 in which the inclination of said end walls is in a direction such that the central portion of the deeply indented portion of the notch between the end walls thereof is wider than opposite sides thereof.

Claims

1. A dummy bar having a head adapted for removably attaching the dummy bar to the end of a continuous metal casting formed in the open-ended mold cavity, said head comprising a lower part and an upper part, the lower part of said head having a cross-sectional configuration and dimension to removably fit in and plug an end of the mold cavity, the upper part of said head having a notch in one side, at least a portion of the wall of the head at the opposite side from the notch being adapted to abut the adjacent portion of the sidewall of the mold cavity when the head is in said end of the mold cavity for preventing molten metal in the mold cavity from penetrating between said adjacent wall portions of the head and mold cavity, said notch having a relatively deeply indented portion and a less deeply indented portion between the deeply indented portion and the end of the head that is within the mold cavity when the head is in said end therEof for forming a hooklike cavity into which molten metal poured into the mold cavity flows and solidifies for attaching the upper part of the dummy bar head to the casting thereby formed, the end wall of the deeply indented portion of the notch, which is adjacent to the bottom wall of the less deeply indented portion of the notch, being undercut to form a barb, the upper part of the dummy bar head and the casting being adapted to be separated subsequently by relative lateral movement away from each other with respect to their longitudinal axis.

3. The dummy bar of claim 2 in which the bottom wall of the deeply indented portion of the notch is approximately parallel to the sidewall of the dummy bar head behind it, and in which the sidewalls and at least one of the end walls of the deeply indented portion of the notch diverge from the bottom wall thereof.