US3717198A

US3717198A - Adjustable dummy bar head for continuous casting

Info

Publication number: US3717198A
Application number: US00109316A
Authority: US
Inventors: H Marti; J Zeller; F Fiala
Original assignee: Concast AG
Current assignee: SMS Concast AG
Priority date: 1970-01-27
Filing date: 1971-01-25
Publication date: 1973-02-20
Anticipated expiration: 1990-02-20
Also published as: ZA71390B; DE2103417A1; FR2077352A1; GB1336248A; FR2077352B1; CA924076A; CH504256A; DE2103417B2; AT311576B; DE2103417C3

Abstract

A dummy bar head for use in continuous casting machines which is adjustable to castings of different widths comprises a coupling member and an intermediate member which links the coupling member to the dummy bar. The coupling member includes at least one end member which is adjustable thereon. The coupling member is provided with an elongated groove of hook-shaped profile to receive molten metal. The end member which is adjustable thereon is also provided with a corresponding hook-shaped profile so that as the end member is adjusted with respect to the coupling member the effective length of the groove is altered correspondingly.

Description

United States Patent 1 Marti et al.

[ 51 Feb. 20, 1973 54 ADJUSTABLE DUMMY BAR HEAD FOR 3,620,285 11 1971 Olsson ..l64/274 NTINU U CASTING CO 0 S FOREIGN PATENTS OR APPLICATIONS [75] Inventors: Heinrich Marti, Zurich; Josef K.

z w Ferdinand Fiala, 1,504,838 10/1967 France ..l64/274 Thalwil, all of Switzerland Primary ExammerR. Spencer Annear [73] Assignee: Concast AG, Zurich, Switzerland Atmmey sandoe, fl d & c li fd 22 Pl d: .25 1971 1 57 ABSTRACT I A l. N l 31 l 1 PP O 6 A dummy bar head for use in continuous casting machines which is adjustable to castings of different [30] Foreign Application Priority Data widths comprises a coupling member and an intermediate member which links the coupling member to Jan. 27, 1970 Switzerland ..l066/7O the dummy bar- The p g member includes at least one end member which is adjustable thereon. lll 164/2132; The p g member is provided with an elongated groove of hook shaped profile to receive molten [58] Field of Search ..164/82, 274, 282 metal The end member which is adjustable thereon is also provided with a corresponding hook-shaped [56] References cued profile so that as the end member is adjusted with UNITED STATES PATENTS respect to the coupling member the effective length of the groove is altered correspondingly. 3,602,290 8/1971 Schmidt et al ..l64/274 3,608,619 9/1971 Bollig et al. ..164/82 10 Claims, 10 Drawing Figures lo l n I PATENTEDFEB201975 3,717,198

sum 20F 3 FIG.5

FIG?

JOSEF K. ZELLER B Y FERDINAND FQALA ATTORNEYS TO HEINRICH MAR l Rs ADJUSTABLE DUMMY BAR HEAD FOR CONTINUOUS CASTING The invention relates to a dummy bar head which is adjustable for the continuous casting of cross-sections of different widths in continuous casting plants, wherein the dummy bar head comprises a coupling member and an intermediate member for linking a coupling member to a dummy bar, the coupling member having an elongated groove of hook-shaped profile of which one side opens against the mold wall and which for starting a continuous casting run is adapted to form a coupling connection with the solidifying casting in withdrawing direction, said connection being releasable by rotary and/or tilting deflection of the dummy bar head out of the longitudinal axis of the casting.

For starting a continuous casting operation a dummy bar attached to a dummy bar head is usually needed. The dummy bar head closes the bottom end of the mold when casting commences and its dimensions depend upon the cross-section of the mold. The dummy bar head is commonly connected to the hot, solidifying casting by pins or bars that are insertable into the head.

It has already been proposed to make the dummy bar head attached to the dummy bar exchangeable to permit of its replacement when the casting cross-section is changed. In such a case a separate head is required for each cross-section that is to be cast. The provision of a large number of different dummy bar heads is not only expensive but as a rule storage space for the heads in direct proximity with the locale for assembling the head to the dummy bar is usually nonexistant, so that the work of replacement also involves the labor of transportation and handling.

It has also been proposed to adjust a dummy bar head to different casting widths by providing extension pieces on the narrow sides of a base member. When casting begins these extensions adjust the sealing face for closing the mold cavity to the different widths of the mold. However, the load-bearing cross-section'of the coupling connection that is formed when casting commences remains constant irrespectively of the different widths of the castings. On the other hand, the forces needed for withdrawing the casting differ in molds of different widths. When the widths of the casting are greater the specific tensile forces affecting the unchanged coupling connection also increase and at the same time the bending stress increases in the solidified shell of the casting which is likewise widened by the presence of the extensions. These additional tensile and bending stresses when conventional extension pieces are used are responsible for the appearance of cracks in the transitional region of the coupling connection with the casting and in the solidified shell that becomes wider because of the presence of the extensions. Such cracks may result in a.

breakout of molten metal.

A dummy bar head already known in the art comprises a coupling member with a recess or groove of hook-shaped profile of which one side bears against the mold wall. The casting which is in course of solidification when the plant is started up forms a coupling connection in withdrawing direction with the coupling member and this coupling connection can be undone by rotary and/or tilting deflection of the dummy bar head out of the longitudinal direction of the casting.

However, this known dummy bar head is not adjustable.

It is therefore the object of the invention to provide a dummy bar head for different casting widths, which is detachable from the casting by rotary and/or tilting deflection, and in which the said adverse effects due to the generation of tensile and bending stresses in the changed solidified shell of the casting when the crosssection of the casting is changed do not arise.

According to the invention this is achieved in that the length of the coupling member is adjustable to different widths of casting and such adjustment of length is accompanied by a change in the length of the coupling groove.

in order to keep the percentage of the width of the casting represented by the length of the groove constant or possibly even to increase this percentage when an adjustment is made to casting of greater widths it is desirable to change the length of the coupling member and the length of the groove by like amounts.

Moreover, in order to achieve sealing edges of low pitch to the mold walls it is advantageous that the coupling member includes at least one end member that determines the effective length of the groove, forms part of the bottom of the mold, and that is slidable endwise along the groove. Such an end member may be locked in desired position by wedging means which permit continuous variable adjustment within the adjustability range and which provide an easy and simple locking device.

In order to minimize the specific pulling forces, the length of the groove may be equal to the width of the mold. In such a case, according to a feature of the invention, exchangeable extension pieces having the hook-shaped profile are provided on at least one end of the coupling member.

For dummy bar heads having a large adjustability range the coupling member may be divisible into two halves parallel to the longitudinal casting axis with the line of division extending perpendicularly across the profile, and exchangeable spacers having the hookshaped profile may be interposed between the divided halves.

The adjustability of such dummy bar heads is considerably simplified if the intermediate member is provided with two guide arms mounted on hinges that extend across the direction of travel of the casting at right angles to the hook-shaped profile.

In a useful arrangement the replacement of the spacers and their central alignment is facilitated if the intermediate member adjoining the coupling member contains space for the accommodation of a set of spacers and these latter are mounted for deflection about a hinge in the intermediate member.

To enable the same intermediate member to be used for coupling members having different adjustability ranges and to permit the coupling member to be easily replaced when worn, the coupling member attached to' the intermediate member may, according to another feature of the invention, be exchangeable.

Furthermore, for a casting of given thickness the same intermediate member may be used for castings of all widths if, according to another feature of the invention, the width of the intermediate member equals the minimum width of casting that is to be cast in the plant.

Some preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:

FIG. 1 is a section, taken on the line I I in FIG. 2, of a dummy bar head provided with slidable end pieces;

FIG. 2 is a side view of one half of the dummy bar head of FIG. 1, looking in the direction of arrow A in FIG. 1;

FIG. 3 is a partial end elevation of a dummy bar head provided with extension pieces;

FIG. 4 is a side view of one half of the dummy bar head in FIG. 3 looking in the direction of arrow B in FIG. 3;

FIG. 5 is a side view of another embodiment;

FIG. 6 is a section taken on the line VI-VI in FIG. 5;

FIG. 7 is a side view of the dummy bar head according to FIG. 5 after adjustment;

FIG. 8 is a side view of another embodiment;

FIG. 9 is a section taken on the line lX-IX in FIG. 8, and

FIG. 10 is a side view of the dummy bar head according to FIG. 8, with insertions interposed.

FIGS. 1 and 2 show a dummy bar head 1 for the continuous casting of cross-sections of different widths. The head 1 consists of a coupling member 2 of height 3 and an intermediate member -4 of height 5. The intermediate member 4 links a dummy bar 6 to the coupling member 2. When starting a casting run a groove having a hook-shaped elongate profile 7 of the coupling member 2 which on one side opens against a wall of the continuous casting mold (not illustrated) forms a coupling connection in withdrawing direction with a continuous casting as it solidifies inside the mold. When the end of the casting has been withdrawn sufficiently far away from the mold the coupling connection is undone by a tilting motion of the dummy bar head 1 out of the longitudinal casting axis about a tipping edge 8. In order to adjust the coupling member 2 to castings of different widths the coupling member 2 includes at least one end member 9 which is movable along a body member 10. Each movable end member 9 may be locked in the desired position by a clamping device comprising a wedging bolt 13 and a sliding stud 14. The body member 10, which is the member coupled to the intermediate member 4, has the groove of hook shaped profile along its entire length and at least one end member 9 is slidable endwise thereon.

FIG. 2 indicates in broken outline the range of adjustability 20 of the end member 9 on one side of the coupling member 2. When the end member 9 is adjusted to different casting widths within this adjustability range 20 the end member forms part of the bottom of the mold for sealing the same during starting, and at the same time the effective length 21 of the groove which is available for the cast metal to enter and thus form the coupling connection through which the withdrawing force is transmitted from the dummy bar head to the end of the continuous casting in the mold is increased by a similar amount 22. The percentage of the total width of the casting represented by the length of the coupling groove forming the coupling connection therefore becomes larger the further the end member 9 is displaced to adapt the coupling member to greater casting widths. For example, assuming the narrowest casting to be 1,400 mm wide, the length 21 of the groove which forms the coupling connection would be 930 mm and thus constitute 66.5 percent of the width of the casting. In order to permit slabs of 1,700 mm width to be cast using the same coupling member the adjustment 20 will be 300 mm. When this adjustment has been made the length 21 of the coupling groove has likewise increased by 300 mm to 1,230 mm, and the percentage of the total width of the casting represented by the length of the hook of cast metal formed in the groove will therefore be 72.3 percent. In other words, it will have increased. The distance 23 between the narrow sides of the head and the hookshaped profile forming the coupling connection remains constant in the case of all cross-sections within the adjustability range 20. The greater withdrawing forces required when the casting is wide are thus distributed over an absolutely and relatively longer hook and no withdrawing forces that give rise to undesirable effects will arise.

The width of the intermediate member 4 corresponds to the minimum width of casting produced in the plant and it may be exchangeably fitted with coupling members 2 having different adjustability range. The dummy bar 6 can be used for castings of any widths and thicknesses to be produced in the plant.

The coupling member 2 may include an end member 9 on only one side or an end member 9 may be fitted on each side. A form of construction comprising only one end member is advantageous when one of the narrow sides of the dummy bar cooperates with a fixed side of the casting guideway.

In order to permit the coupling member to be quickly and accurately adjusted to the required width the end members 9 and the body member 10 are provided with holes 24 into which a mechanical, pneumatic or hydraulic manipulating device is insertable. Such manipulating devices may be fitted with adjustable.

stops which enable the end members to be exactly symmetrically adjusted to any cross-section.

FIGS. 3 and 4 show another embodiment of a coupling member which is here generally indicated by the reference numeral 30. It is connected to an intermediate member 31 which is merely symbolized in the drawing. The length of the groove .of hook-shaped profile 32 which forms the coupling connection corresponds to the width of the mold. Exchangeable extension pieces 34 likewise having grooves of profile 32 are secured by bolts 33 to those ends 36 of the coupling member 30 which are normal to the profile 32. However, such extension pieces 34 may be provided on only one side of the coupling member 30.

In FIG. 4 the width of the extension piece 34 is indicated at 35. According to the desired width of the casting an extension piece 34 of appropriate width 35 is used. The coupling member 30 is adjusted to the desired casting width by substitution of the extension pieces 34. The extension piece 34 and its profile 32 simultaneously form the required bottom part of the mold. The clearance gap between the coupling member 30 and the mold wall is preferably sealed with a refractory paste.

The coupling member 40 shown in FIGS. 5 and 6 is divisible into two halves substantially mid-way between its ends and the line of division crosses the groove of profile 41 at right angles to the direction of elongation of the profile 41. The divided coupling member 40 is held together by a tiebolt 42. This coupling member 40 has gently inclined sealing edges 43 facing the mold walls since these are easier to seal than when they are steep. In order to facilitate expanding the coupling member 40 in adjusting direction the intermediate member 44 has two guide arms 45 mounted on hinges 46. The hinges 46 run across the direction of travel of the casting and at right angles to the profile 41. A joint 47 between the hinges 46 and the coupling member 40 serves to confer the necessary mobility to the dummy bar head. Abutment faces 48 between the guide arms 45 take up the thrusts of the rollers that withdraw and guide the casting and they prevent the set-back flanges 49 of the hinges from being loaded.

In FIG. 7 the coupling member 40 is shown adapted to a wider section casting by the interposition of an exchangeable spacer 60 of a length 61 provided with the coupling groove of profile 41. The spacer is secured by the tiebolt 42. The two guide arms 45 form the desired transition cone from the intermediate member 44 to the coupling member 40.

In FIG. 8 and FIG. 9 a coupling member 40 which is divided in the middle is attached to an intermediate member 82 by a slideway 81. The portion of the intermediate member 82 directly adjoining the coupling member 40 contains a space 85 sufficient for the accommodation of spacer members 84. In FIG. 8 the coupling member 40 is shown contracted to its minimum width and all the spacer members 84 in an inoperative position in which they are held and located inside the intermediate member 82 by retaining bars 86. The spacer members 84 are hingeably mounted in the intermediate member 82 to swing about a hinge pin 87. Centering and interposition of the spacer members 84 between the halves of the coupling member 40 is facilitated by this arrangement.

In FIG. 10 three of the five illustrated spacer members 8.4 have been interposed between the halves of the coupling member 40 and secured by tiebolts 42 for the purpose of widening the dummy bar head. The space required for the interposition of the spacer members 84 is created by pushing the two halves of the coupling member apart along in the slideway, parallel to the profile 41. The retaining bars 86 keep the two inoperative spacer members 84 in place in the intermediate member.

In dummy bar heads that are to provide firstly a wide adjustability range amounting to say 50 percent of the minimum casting width and secondly continuous stepless adjustability within this range, slidably movable end members 9 as shown in FIG. 1 may be combined with a dummy bar head according to FIGS. 5 to 10.

In another alternative coupling member may be adjusted to different widths of casting by extension members lacking a coupling profile and having say a solid cross-section. The length of the profile in such an arrangement may then be varied in steps by removable inserts that limit the length of the profile.

We claim as our invention:

1. A dummy bar head for use in continuous casting machines which is adjustable to castings of different widths, comprising a coupling member having an elonated groove of hook-shaped profile extendin engthwise thereof adapted to receive molten meta which solidifies therein, and means mounted on said coupling member for adjusting the effective length thereof and at the same time adjusting the effective length of said groove.

2. A dummy bar according to claim 1 in which said adjusting means comprises at least one end member mounted on said coupling member and having a corresponding hook-shaped profile extending into said groove, said end member being slidable thereon, and means for locking said end member in any desired position of adjustment.

3. A dummy bar head according to claim 2 in which said locking means comprises a wedge.

4. A dummy bar head according to claim 1 in which said adjusting means comprises at least one extension piece secured to the end of said coupling member, said extension piece having a groove of corresponding hook-shaped profile aligned with the groove of the coupling member and forming an extension thereof.

5. A dummy bar head according to claim 1 in which said coupling member consists of two similar halves, and in which said adjusting means comprises one or more spacers interposed between said halves, each of said spacers having a groove of corresponding hookshaped profile aligned with the groove of the coupling member and forming an extension thereof.

6. A dummy bar head according to claim 5 in which the dummy bar head is connected to the dummy bar by an intermediate member.

7. dummy bar head according to claim 6 in which said adjusting means includes a pair of guide arms pivotally mounted on said intermediate member on hinges extending at right angles to said groove.

8. A dummy bar head according to claim 6 in which said adjusting means includes a plurality of spacer members hinged to said intermediate member.

9. A dummy bar head according to claim 6 in which the width of the intermediate member corresponds to the minimum width of the casting mold.

10. A dummy bar head according to claim 1 in which said adjusting means adjusts the effective length of the coupling member and the effective length of said groove by equal amounts.

Claims

1. A dummy bar head for use in continuous casting machines which is adjustable to castings of different widths, comprising a coupling member having an elongated groove of hook-shaped profile extending lengthwise thereof adapted to receive molten metal which solidifies therein, and means mounted on said coupling member for adjusting the effective length thereof and at the same time adjusting the effective length of said groove.

5. A dummy bar head according to claim 1 in which said coupling member consists of two similar halves, and in which said adjusting means comprises one or more spacers interposed between said halves, each of said spacers having a groove of corresponding hook-shaped profile aligned with the groove of the coupling member and forming an extension thereof.