US3823762A

US3823762A - Roll-couple, continuous-strip caster

Info

Publication number: US3823762A
Application number: US00343494A
Authority: US
Inventors: E Wondris
Original assignee: National Steel Corp
Current assignee: National Steel Corp
Priority date: 1973-03-21
Filing date: 1973-03-21
Publication date: 1974-07-16
Anticipated expiration: 1991-07-16

Abstract

Roll-couple, continuous-strip caster in which arcuate, resilient refractory seals are employed to elastically adapt to the peripheral surfaces of the casting rolls and establish sealing contact with the rolls to prevent flow of molten metal between rolls and vessel walls. The seals can be segmented for movement toward the casting rolls, to accommodate wear of the seals while still maintaining sealing contact with the rolls. The seals can be moved axially along the rolls to adjust the width of the cast strip without interruption of the casting operation. Peripheral bands of thermal insulation can be employed on the rolls, which are water-cooled, to reduce heat transfer from the seals to the rolls and thereby reduce tendency for molten metal to solidify on the seals. Heaters in the seals can be used to further reduce such tendency.

Description

United States Patent [191 Wondris Y v 1i] 1 3,823,762

[451 July 16, 1974 ROLL-COUPLE, CONTINUOUS-STRIP CASTER [75] Inventor: Erich F. Wondris, Pittsburgh, Pa,

[73] Assignee: National Steel Corporation,

Pittsburgh, Pa.

[22] Filed: Mar. 21, 1973 [21] Appl. No.: 343,494

[52] US. Cl. 164/277, 164/283 M [51] Int. Cl B22d 11/06 [58] Field of Search 164/87, 277, 283 M [56] References Cited UNITED STATES PATENTS 1,965,603 7/1934 Low 164/277 X 3,447,590 6/1969 Olsson 164/277 3,498,362 3/1970 Lewis 164/277 X FOREIGN PATENTS OR APPLICATIONS 986,078 3/1951 France 164/277 Primary Examiner-R. Spencer Annear Attorney, Agent, or FirmShanley & ONeil [5 7] ABSTRACT Roll-couple, continuous-strip caster in which arcuate, resilient refractory seals are employed to elastically adapt to the peripheral surfaces of the casting rolls and establish sealing contact with the rolls to prevent flow of molten metal between rolls and vessel walls.

The seals can be'segmented for movement toward the casting rolls, to accommodate wear of the seals while still maintaining sealing contact with the rolls. The

I seals can be moved axially along the rolls to adjust the width of the cast strip without interruption of the casti ing operation. Peripheral bands of thermal insulation can be employed on the rolls, which are water-cooled,

to reduce heat transfer from the seals to the rolls and thereby reduce tendency for molten metal to solidify on the seals. Heaters in the seals can be used to further reduce such tendency.

9 Claims, 13 Drawing Figures PATENTED JUL 1 81974 SHEET 1 0f 4 PAIENTEU JUL 1 61914 SHEET 2 OF 4 FIGS PATENIED JUL I 61914 SHEET N (If 4 HGIO BACKGROUND OF THE INVENTION Continuous-strip casters employing a roll couple partially immersed in molten metal are a desirable approach to the production of strip in continuously cast form. This is because such casters expose a large surface area of the casting rolls to the molten metal, which makes for fast solidification rates and, therefore, high casting speeds and production rates.

In such continuous-strip casters, it is desirable to receive the end portions of the casting rolls in portions of the walls which define the casting vessel, because this permits deep immersion of the rolls while providing for true edges on the cast strip. With such an arrangement there is a need for an effective seal against flow of molten metal between the rolls and the vessel walls, and a main object of the invention is the fulfillment of this need.

Other problems associated with strip casters of the foregoing type include wear of the seals by rotation of the rolls, solidification of molten metal on the seals, and the relative inflexibility of such casters with respect to the width of the strip being cast. Other objects of the invention are to overcome these problems.

Still other objects and advantages of the invention will appear from the following detailed description which, considered inconnection with the accompanying drawings, disclosesseveral embodiments of the invention for purposes of illustration only.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevational view of a continuous-strip casting apparatus embodying principles of the invention.

FIG. 2 is a longitudinal cross-sectional view of the apparatus of FIG. 1.

FIG. 3 is a cross-sectional view on the plane designated by line 3-3 of FIG. 1.

FIG. 4 is a top view of the apparatus of FIG. 1.

FIG. 5 is a cross-sectional view on the plane designated by line 5-5 in FIG. 1.

FIG. 6 is a cross-sectional view, similar to FIG. 5, illustrating details of a second continuous-strip casting apparatus embodying principles of the invention.

FIG. 7 is an elevational view of a third continuousstrip casting apparatus embodying principles of the invention.

FIG. 8 is an elevational view of details of the apparatus of FIG. 7.

FIG. 9 is a cross-sectional view on the plane desig-' nated by line 99 of FIG. 6.

FIG. 10 is an elevational view of details of the structure of FIG. 9.

FIG. 11 is a cross-sectional view on the plane designated by line ll -ll of FIG. 10.

FIG. 12 is a cross-sectional view, similar to FIG. 5, illustrating details of a fourth continuous-strip casting apparatus embodying principles of the invention.

FIG. 13 is a detail view on the section plane designated by line 13-13 on FIG. 12.

Reference characters with the letter suffixes A, B and C, denote elements similar to elements designated with the corresponding reference character without the suffix.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS In FIG. ll, continuous-strip caster 12 comprises refractory walls defining a vessel 14 (see also FIG. 2) for a melt of molten casting metal. The metal can, for example, be aluminum. As used herein, the term aluminum embraces aluminum-base alloys as well as the pure metal. However, it will be'understood that other metals can be used.

The walls of vessel l4 include steel-cased, refractorylined, confronting back and

front walls

16, 18 respectively (see also FIG. 3). The vessel walls also include opposite side walls in the form of opposed

refractory weirs

20, 22. The weirs are provided for overflowing molten metal from vessel 14 into

catch basins

24, 26, respectively. Each weir extends from back wall 16 to front wall 18 of vessel 14. Vessel 14 also has a bottom wall, which is designated at 28. The exposed portions of the surface of the melt, and the catch basins, are covered by protective-

atmosphere hoods

30, 32. An inert gas (e.g., argon) is supplied to the interior of the hoods through conduits 34, to protect the molten metal from oxidation.

Caster 112 comprises a roll

couple including rolls

36, 38 having parallel, horizontal axes of rotation and having cylindrical

peripheral surfaces

40, 42 respectively.

The rolls are immersed in the melt over equal parts of their peripheral surfaces. The rolls are deeply immersed in the melt; the melt-contact angle can be in excess of of the periphery of each roll.

The periphal surface of each roll has opposite end portions 44, 46 (FIG. 3) which are respectively carried by vessel walls l6, l8.

Walls

16, 18 respectively include sealing

members

50, 52 which prevent molten metal from flowing between the rolls and the vessel walls and thereby escaping from the vessel or otherwise interfering with the casting operation. Sealing

members

50, 52 are similar to one another, so description of one will impart an understanding of both.

Sealing member 52 has a pair of arcuate sealing surfaces 54,'56 (FIG. 1), each of which receives an end portion of a roll. Each sealing surface is cylindrical and is complementary to the peripheral surface of the received roll. Sealing member 52 also has external

cylindrical surfaces

58, 60 which are fitted in complementarily-

shaped recesses

59, 61 in the lower portions of the vessel walls. The sealing member is secured to steel casing portion 48 of the vessel walls by stud bolts, as 62, which-pass through flange 64 on the sealing member (see also FIG. 5).

Rolls

36, 38 are driven by motor 66 (FIG. 3) in counter-rotating movement in the directions indicated by arrows 68 (FIG. 1). Coolant water is passed through passageways 34 (FIG. 3) in each roll as shown by directional arrows, as 70, to effect cooling of the roll. As a result of the cooling and rotative movements of the rolls, molten metal solidifies on the peripheral surface of each roll axially between sealing

members

50, 52.

-The metal solidifies in progressively increasing thicknesses from the respective roll dipping points 72, 74 (FIG. 2) to the nip of the rolls. In the roll nip, solidified metal on each roll is merged with solidified metal on the other roll and the merged metal is formed into a continuous strip 76. Strip 76 is trained upwardly from the casting rolls and around guide roller 78 to coiling equipment (not shown).

Molten metal is continuously supplied to vessel 14 through conduit 80, which discharges molten metal into the vessel directly below the roll nip. Baffle 82 is positioned in vessel 14 in confronting relation to the conduit exit opening, for deflecting discharged molten metal upwardly toward the roll nip. The molten metal flow path is pictorially depicted by the directional arrows, as 84. The upflowing molten metal divides into two branches, one branch passing upwardly beside roll 36 to weir 20 and the other branch passing upwardly beside roll 38 to weir 22. The molten metal overflowing the weirs and received in

catch basins

24, 26 is conducted through

conduits

86, 88 to a common receiver (not shown) and, after being filtered, thermally conditioned (as by reheating), and merged with makeup metal, is recirculated to vessel 14 through conduit 80.

Each of the sealing members which receive the end portions of the casting rolls is composed of a resilient refractory material which elastically adapts to the peripheral surfaces of the rolls and establishes sealing contact with the rolls to prevent flow of molten metal between the rolls and the sealing member lt will be appreciated that if desired only the arcuate sealing surfaces can be made of the resilient refractory material; however, it is convenient to form the entire sealing member of such material.

Such resilient refractory materials are well known in the refractory art. One suitable material for the sealing members is an alumina-silica refractory which consists essentially of SiO A1 0 and minor amounts of Na O, B 0 and M g0, and which is sold under the trade name Fiberfrax by the Carborundum Company. Another material which may be used is a fibrous refractory which consists of diatomaceous silica, asbestos fiber, and a binder, and which is sold under the trade name Marinite by the Johns-Manville Company. Asbestos may also be used.

In order to prevent excessive heat losses from the sealing members to the watercooled rolls, and thus reduce tendency for molten metal to solidify on the sealing members and thereby tear the cast strip, each end portion of the peripheral surface of each roll includes a peripheral band 88 (FIGS. 3-5) of thermal insulation.

Bands 88 oppose the sealing members which receive the end portions of the rolls. Bands 88 for example can be of the same refractory material as the sealing members.

In order to further reduce tendency for molten metal to solidify on the sealing members, the sealing members can be heated by electrical heaters 86 (FIGS. 1, 5). Heaters 86 are inside the sealing members and are spaced along the arcs of the sealing surfaces of the sealing members. The seals are maintained at a temperature sufficient to prevent solidification and metal buildup on the sealing members. When casting aluminum, a seal temperature of about l,250F is satisfactory. It will be appreciated that heating means other than electrical can be used. For example, hot gases could be ducted through the sealing members.

If desired, the sealing members can be constructed for movement axially along the rolls for adjusting the width of the cast strip. A construction of this nature is illustrated in FIG. 6, where sealing member 52A includes a reinforcing steel plate 90 which is secured to the refractory portion of the sealing member by anchor 92. Plate 90 carries an annular retainer 94 which rotatably receives an outwardly projecting flange 95 on ad- 36A, with cylindrical surface 58A sliding along complementary cylindrical surface 59A on the fixed portion of vessel wall 18A. Such inward movement of sealing member 52A restricts the effective length of peripheral casting surface 40A, thus narrowing the strip, while still maintaining fluidtight seals between roll and sealing member and between

cylindrical surfaces

58A, 59A. It will be appreciated that sealing member 52A does not have a flange such as 64 in FIG. 5, and of course there are no such bolts as 62 in FIG. 5 to secure the sealing member to the vessel shell. Otherwise, sealing member 52A corresponds to sealing member 52.

Rotation of bolt 96 in-the opposite circumferential direction extracts sealing member 52A, to widen the strip. In a construction such as in FIG. 6, it can be desirable to eliminate the insulating bands on the end portions of the peripheral casting surfaces of the rolls, because the insulation provided by the bands would tend to interfere with solidification of metal on the casting surfaces when the sealing members are positioned outboard of the insulating bands. It will be appreciated that a plurality of adjuster bolts 96 are provided, and the bolts are spaced along the arcs of the sealing surfaces of the sealing members to move the sealing members inwardly over the cylindrical surfaces (as 59A) on the fixed portions of the vessel walls. If desired, the

sealing member at only one end of the rolls can be constructed for axial adjustment; however, when both sealing members are axially movable, a wider range of strip widths can be produced.

Notwithstanding the resiliency of the sealing members, rotation of the casting rolls naturally abrades and wears away the sealing surfaces and eventually reduces the effectiveness of the molten metal seals. In the constructions of FIGS. 1-6, this condition would call for shutdown of the casting machine for replacement of the sealing members. Longer service life can be obtained in a construction such as in FIGS. 7-11, where each sealing member is divided into a plurality of sealing segments and. each sealing segment is moved toward the peripheral surface of the associated roll to maintain sealing contact with the roll as the portion of the sealing surface on the segment is worn away. Description of the sealing member at one end of the rolls imparts an understanding of the sealing members at both ends.

In FIG. 7, sealing member 528 is divided into a plurality of

segments

102, 104, 106, 108, 110, 112 and ment toward the roll.

Each of sealing segments 1112-111) is biased for inward movement by at least one pressure device 121). Each pressure device 120 includes a spring 121 (FIG. 9) which is compressed against a bracket 122 which is secured to metal casing portion 48B of vessel wall 18B. As the portion of the sealing surface on each sealing segment (e.g., the portion of sealing surface 548 on segment 104) wears away, the sealing segment is urged axially relative to the roll by the spring and thus is moved along the inclined surfaces inwardly toward the roll and thereby maintains sealing contact with the roll while still maintaining a fluidtight seal between the sealing number and the fixed portion of the vessel wall. Sealing segments 112 114 are inwardly biased by springs 124 which are compressed against fixedposition bracket125.

Sealing segments

112, 114 move directly downwardly instead of along inclined planes, since there is no need for maintenance of a molten metal seal at the top surfaces of these sealing segments.

In addition to maintaining continuous sealing contact, the segmenting and pressure-biasing of the sealing members is advantageous in providing a-uniform pressure distribution between rolls and sealing members along the arcs of the sealing surfaces. If desired, adjuster bolts-may be used in lieu of springs to urge the sealing segments axially.

It will be observed that movement of the sealing segments to maintain sealing contact with the rolls will have a narrowing effect on the strip width, but such effeet is minor. In the embodiment of FIGS. 12-13, the feature of strip width adjustment as in FIG. 6 is combined with segmenting of the sealing members and movement of the segments to accommodate wear of the seals as in the embodiment of FIGS. 7-11. In the embodiment of FIGS. 12-13, the sealing members are segmented as in the embodiment of FIGS. 7-11 and further, each of the plurality of segments corresponding to segments 102-110 of FIG. 7 is subdivided longitudinally with respect to the rolls into two parts. For example, sealing segment 104C (FIG. 12) is divided into

parts

126, 128, and description of the arrangement of this sealing segment imparts an understanding of all.

Part 126 of sealing segment 104C is used to maintain sealing contact with roll 36C, and part 128 permits strip width adjustment. Inclined surface 116C is formed on part 126, and spring 121C urges part 126 axially inwardly relative to roll 36C so that

parts

126, 128 move as a unit over

inclined surfaces

116C, 118C toward the roll to maintain part 128 incontinuous sealing relation with the roll. Retainer 94C in this embodiment is elongated in a direction toward the roll (see also FIG. 13), and also contains clearance axially relative to the roll .to allow movement of part 128 inwardly and toward the roll without interference from adjuster bolt 96C. To adjust the strip width, bolt 96C is rotated to engage outwardly projecting flange 95C on the bolt with either inturned lip 97C of retainer 94C or with plate 90C, depending upon whether the strip is to be widened or narrowed. The bolt is then further rotated to move part 128 axially relative to roll 36C. During such action, cylindrical surface 130 on part 128rides over complementary cylindrical surface 132 on part 126 and if necessary suitable holding means such as a clamp (not shown), can be provided to prevent part 126 from moving with part 128. After a widening width adjustment, bolt 96C is rotated so that flange 95C in retainer 94C 6 is spaced from inturned lip 97C of the retainer and thus will not interfere with the movement of part 128 which is effected to accommodate seal wear.

It will be appreciated that the segmented sealing members of the embodiments of FIGS. 7-13 include heating means (not shown) like the heaters of the embodiments of FIGS. 1-6. It will further be appreciated that, while the sealing members in the embodiments of FIGS. 1-6 are depicted as being of one piece, if convenient they can be made in a plurality of pieces fixed together so that the pieces in assembly act as one piece. And in this connection it is to be observed that the sealing members can be formed integrally with the remainder of the refractory lining portions of the vessel walls should it be desired to use the resilient refractory materials of the seals for the remainder of the vessel walls.

Apparatus according to the invention are highly advantageous. The resilient refractory sealing members establish an effective seal with the casting rolls to prevent flow of molten metal between rolls and vessel walls; Segmenting of the seals for movement toward the casting rolls accommodates wear of the seals while maintaining sealing contact with the rolls, while maintaining the vessel walls tight against escape of molten metal, and further, obtaining uniform pressure distribution along the seal-roll contact zone. The peripheral bands of thermal insulation on the rolls prevent excessive heat loss from the seals to the rolls and thereby reduce tendency for molten metal to solidify on the seals. The heaters in the seals coact with the bands of insulation to further reduce tendencies for solidification and metal buildup on the seals. And, the width of the cast strip can be adjusted without interruption of the continuous casting operation.

Although the invention has been described in connection with several illustrated embodiments, many modifications can be made as will be apparent to those skilled in the art. Accordingly, reference will be made to the appended claims for definition of the scope of the invention.

I claim:

l. Continuous-strip casting apparatus, comprising means including walls defining a vessel for molten metal, and

strip-forming means including a roll couple and means for rotating the rolls,

each roll having a peripheral surface for partial imeach sealing surface receiving an end portion of the peripheral surface of a roll,

at least the sealing surfaces of the sealing members comprising resilient refractory means for elastically adapting to the peripheral surfaces of the rolls and establishing sealing contact with the rolls.

2. Apparatus as defined in claim 1,

each sealing member including a plurality of sealing segments,

' each sealing segment including a portion of a sealing surface,

the sealing means including means for moving each sealing segment toward a roll for maintaining the segment in sealing contact with the roll as the portion of the sealing surface on the sealing segment wears away under rotation of the roll.

3. Apparatus as defined in claim 1, in which the rolls have longitudinal axes, and including means for moving at least a portion of at least one of the sealing members axially along the rolls for adjusting the strip width.

4. Apparatus as defined in claim 1,

the strip-forming means including means for cooling the rolls,

the end portions of the peripheral surfaces of the rolls including peripheral bands of thermal insulation opposing the sealing surfaces for reducing heat transfer from the sealing surfaces to the rolls.

5. Apparatus as defined in claim 4, including means for heating the sealing members.

6. Continuous-strip casting apparatus, comprising means including .walls defining a vessel for molten metal,

strip forming means including a roll couple and means for rotating the rolls,

each roll having a longitudinal axis and having 21 peripheral surface for partial immersion in the molten metal,

the peripheral surface of each roll having opposite end portions,

the walls of the vessel including confronting walls contacting the end portions of the peripheral surfaces of the rolls,

the confronting walls including sealing means for preventing flow of molten metal between the peripheral surfaces of the rolls and the vessel walls,

the sealing means including a sealing member on each of the confronting walls,

the sealing members having arcuate sealing surfaces,

each sealing surface receiving an end portion of the peripheral surface of a roll,

at least the sealing surfaces of the sealing members comprising resilient refractory means for elastically adapting to the peripheral surfaces of the rolls and establishing sealing contact with the rolls,

each sealing member including a plurality of sealing segments,

each sealing segment including a portion of a sealing surface,

the sealing means including means for moving each sealing segment toward a roll for maintaining the segment in sealing contact with the roll as the portion of the sealing surface on the sealing segment wears away under rotation of the roll,

the means for moving each of a plurality of the sealing segments including a first inclined surface on the sealing segment,

a second inclined surface on a vessel wall,

the first and second inclined surfaces sloping toward the roll and cooperating with one another for guiding the sealing segment toward the roll, and

pressure means for urging the sealing segment axially relative to the roll for moving the sealing segment along the inclined surfaces toward the roll.

7. Apparatus as defined in claim 6, including means for moving at least a portion of each sealing member axially along the rolls for adjusting the strip width.

8. Apparatus as defined in claim 6,

the strip-forming means including means for cooling the rolls,

9. Apparatus as defined in claim 8, including means located inside the sealing members for heating the sealing members.

Claims

1. Continuous-strip casting apparatus, comprising means including walls defining a vessel for molten metal, and strip-forming means including a roll couple and means for rotating the rolls, each roll having a peripheral surface for partial immersion in the molten metal, the peripheral surface of each roll having opposite end portions, the walls of the vessel including confronting walls contacting the end portions of the peripheral surfaces of the rolls, the confronting walls including sealing means for preventing flow of molten metal between the peripheral surfaces of the rolls and the vessel walls, the sealing means including a sealing member on each of the confronting walls, the sealing members having arcuate sealing surfaces, each sealing surface receiving an end portion of the peripheral surface of a roll, at least the sealing surfaces of the sealing members comprising resilient refractory means for elastically adapting to the peripheral surfaces of the rolls and establishing sealing contact with the rolls.

2. Apparatus as defined in claim 1, each sealing member including a plurality of sealing segments, each sealing segment including a portion of a sealing surface, the sealing means including means for moving each sealing segment toward a roll for maintaining the segment in sealing contact with the roll as the portion of the sealing surface on the sealing segment wears away under rotation of the roll.

4. Apparatus as defined in claim 1, the strip-forming means including means for cooling the rolls, the end portions of the peripheral surfaces of the rolls including peripheral bands of thermal insulation opposing the sealing surfaces for reducing heat transfer from the sealing surfaces to the rolls.

6. Continuous-strip casting apparatus, comprising means including walls defining a vessel for molten metal, strip-forming means including a roll couple and means for rotating the rolls, each roll having a longitudinal axis and having a peripheral surface for partial immersion in the molten metal, the peripheral surface of each roll having opposite end portions, the walls of the vessel including confronting walls contacting the end portions of the peripheral surfaces of the rolls, the confronting walls including sealing means for preventing flow of molten metal between the peripheral surfaces of the rolls and the vessel walls, the sealing means including a sealing member on each of the confronting walls, the sealing members having arcuate sealing surfaces, each sealing surface receiving an end portion of the peripheral surface of a roll, at least the sealing surfaces of the sealing members comprising resilient refractory means for elastically adapting to the peripheral surfaces of the rolls and establishing sealing contact with the rolls, each sealing member including a plurality of sealing segments, each sealing segment including a portion of a sealing surface, the sealing means including means for moving each sealing segment toward a roll for maintaining the segment in sealing contact with the roll as the portion of the seaLing surface on the sealing segment wears away under rotation of the roll, the means for moving each of a plurality of the sealing segments including a first inclined surface on the sealing segment, a second inclined surface on a vessel wall, the first and second inclined surfaces sloping toward the roll and cooperating with one another for guiding the sealing segment toward the roll, and pressure means for urging the sealing segment axially relative to the roll for moving the sealing segment along the inclined surfaces toward the roll.

8. Apparatus as defined in claim 6, the strip-forming means including means for cooling the rolls, the end portions of the peripheral surfaces of the rolls including peripheral bands of thermal insulation opposing the sealing surfaces for reducing heat transfer from the sealing surfaces to the rolls.