US20130119094A1

US20130119094A1 - Casting thin strip and delivery nozzle therefor

Info

Publication number: US20130119094A1
Application number: US13/464,188
Authority: US
Inventors: Rama Ballav Mahapatra; Hisahiko Fukase
Original assignee: Nucor Corp
Current assignee: Nucor Corp
Priority date: 2011-05-06
Filing date: 2012-05-04
Publication date: 2013-05-16

Abstract

A method of casting metal strip and equipment therefor where an elongated metal delivery nozzle extending along in a continuous caster with at least one segment having a main portion adapted to deliver molten metal in the casting pool above the nip along the metal delivery nozzle and an end portion adjacent side dams having a reservoir portion with first and second passages adapted to deliver molten metal into a molten metal pool adjacent the side dams while shells are forming on the casting rolls. The first passages are adapted to deliver molten metal shallowly into the casting pool adjacent the side dams, and the second passages adapted to deliver molten metal deeper into the casting pool than the first passages adjacent the side dams to inhibit formation of skulls during the formation of the cast strip during a casting campaign.

Description

RELATED APPLICATION

This application claims priority to and the benefit of U.S. Provisional Patent Application No. 61/483,405, filed May 6, 2011, the disclosure of which is incorporated herein by reference.

BACKGROUND AND SUMMARY OF THE INVENTION

This invention relates to making thin strip and, more particularly, casting of thin strip by a twin roll caster.
It is known to cast metal strip by continuous casting in a twin roll caster. Molten metal is introduced between a pair of counter-rotating horizontal casting rolls which are cooled so that metal shells solidify on the moving roll surfaces and are brought together at the nip between the casting rolls to produce a solidified strip product delivered downwardly from the nip. The term “nip” is used herein to refer to the general region at which the rolls are closest together. The molten metal may be poured from a ladle into a smaller vessel or tundish/distributor, from which it flows through a metal delivery nozzle located above the nip, which directs the molten metal to form a casting pool supported on the casting surfaces of the rolls above the nip. This casting pool may be confined at the ends of the casting rolls by side plates or dams held in sliding engagement adjacent the ends of the rolls.
In casting thin strip by twin roll casting, the metal delivery nozzles receive molten metal from the movable tundish and deposit the molten metal in the casting pool in a desired flow pattern. Previously, various designs have been proposed for delivery nozzles involving a lower portion submerged in the casting pool during a casting campaign, and having side openings through which the molten metal is capable of flowing laterally into the casting pool outwardly toward the casting surfaces of the rolls. Examples of such metal delivery nozzles are disclosed in Japanese Patent No. 09-103855 and U.S. Pat. No. 6,012,508. In prior art metal delivery nozzles, there has been a tendency to produce thin cast strip that contains defects from uneven solidification at the chilled casting surfaces of the rolls.
In the past, the formation of pieces of solid metal known as “skulls” in the casting pool in the vicinity of the confining side plates or dams have been observed. These skulls become “snake-eggs” in the cast strip when swallowed and passed through the nip into the cast strip. The rate of heat loss from the casting pool is higher near the interface between side dams and the casting rolls (called the “triple point region”) due to conductive heat transfer through the side dams to the casting roll ends. This localized heat loss near the side dams has a tendency to form skulls of solid metal in that region, which can grow to a considerable size and fall between the casting rolls and cause defects in the cast strip. An increased flow of molten metal to these regions near the side dams and meniscus of the casting pool have been provided by separate direct flows of molten metal to these regions. Examples of such proposals may be seen in U.S. Pat. No. 4,694,887 and in U.S. Pat. No. 5,221,511. Increased heat input to these regions has inhibited formation of skulls.
Nevertheless, we have continued to observe skulls in the triple point region and also deeper into the casting pool adjacent the side dams. It was thought that such formation of skulls was near the meniscus of the casting pool as the shells were initially formed. We have now discovered that such skulls can also form deeper in the casting pool as the shells continue to form as the shells move toward the nip. We have found that the formation of skulls can be substantially reduced by providing different flows through first and second passages of a reservoir portion of the metal delivery nozzle, the first passages delivering the molten metal shallowly into the casting pool adjacent the side dams and the second passages delivering the molten metal deeper into the casting pool adjacent the side dams while shells are formed in the casting rolls.
The present invention provides a method of casting thin strip with the delivery nozzle and an improved delivery nozzle therefor. Disclosed is a method of casting metal strip comprising:

- (a) assembling a pair of casting rolls laterally disposed to form a nip between them and between side dams adapted to maintain a molten metal pool supported by the casting rolls,
- (b) assembling an elongated metal delivery nozzle extending along and above the nip with at least one segment having a main portion adapted to deliver molten metal in the casting pool along the metal delivery nozzle and an end portion adjacent side dams having a reservoir portion having first and second passages adapted to deliver molten metal into a molten metal pool adjacent the side dams while shells are forming on the casting rolls, the first passages adapted to deliver molten metal shallowly into the casting pool adjacent the side dams and the second passages adapted to deliver molten metal deeper into the casting pool than the first passages adjacent the side dams,
- (c) introducing molten metal through the elongated metal delivery nozzle to form a casting pool of molten metal supported on the casting rolls above the nip, and through the first and second passages in the reservoir portion in the end portions into the casting pool, and
- (d) counter rotating the casting rolls to deliver cast strip downwardly from the nip.

The first and second passages of the reservoir portion may be substantially parallel. The first and second passages of the reservoir portion may be between 5 and 30 millimeters apart, between edge portions of the passages. The first and second passages themselves may be generally 7 to 12 millimeters in diameter, and the first and second passages may be of different diameter as desired to deliver the molten metal into the casting pool at the desired location adjacent the side dams.
The method may be provided with a reservoir portion in the end portion of each segment having longitudinally extending weirs adjacent the side walls of the inner trough adapted to allow molten metal to flow over the weirs between the reservoir portion and the main portion of the metal delivery nozzle.
The method of casting metal strip may be also provided with dual first and second passages in each reservoir portion of the metal delivery nozzle adjacent the side dams. In this embodiment the first and second passages may be provided in pairs on both sides of the side dams near the casting rolls. Again, the first and second passages of the reservoir portion may be between 5 and 30 millimeters apart, measured between near wall portions of the passages. The first and second passages themselves again may be generally 7 to 12 millimeters in diameter, and the first and second passages may be of different diameter as desired to deliver the molten metal into the casting pool at the desired locations.
Also disclosed is a metal delivery apparatus for casting metal strip comprising at least one elongated segment having a main portion adapted to deliver molten metal in the casting pool along the metal delivery nozzle and an end portion adjacent side dams having a reservoir portion having first and second passages adapted to deliver molten metal into a molten metal pool adjacent the side dams while shells are forming on the casting rolls, the first passages adapted to deliver molten metal shallowly into the casting pool adjacent the side dams and the second passages adapted to deliver molten metal deeper into the casting pool than the first passages adjacent the side dams.
The first and second passages of the reservoir portion of the metal delivery nozzle may be between 5 and 30 millimeters apart, measured between near wall portions of the passages. The first and second passages of the reservoir portion of the metal delivery nozzle may or may not be substantially parallel. In any case, the first and second passages of the metal delivery nozzle may be generally 7 to 12 millimeters in diameter, and the first and second passages may be of different diameter as desired to deliver the molten metal into the casting pool at the desired locations adjacent the side dams.
The metal delivery apparatus for casting metal strip may be provided with a reservoir portion in the end portion of each segment having longitudinally extending weirs adjacent the side walls of the inner trough adapted to allow molten metal to flow over the weirs between the reservoir portion and the main portion of the metal delivery apparatus.
The metal delivery apparatus for casting metal strip may be also provided with dual first and second passages in each reservoir portion of the metal delivery nozzle adjacent the side dams. In this embodiment, the first and second passages may be provided in pairs adjacent both sides of the side dams near the casting rolls. Again, the parts of the first and second passages of the reservoir portion may be between 5 and 30 millimeters apart, between edge portions of the passages. The first and second passages of the reservoir portion of the metal delivery nozzle may be or may not be substantially parallel as desired. The first and second passages of the metal delivery apparatus also may be generally 7 to 12 millimeters in diameter, and the first and second passages may be of different diameter as desired to deliver the molten metal into the casting pool at the desired location.
The metal delivery apparatus for casting metal strip may have dual first and second passages in each reservoir portion of the metal delivery nozzle. The first and second passages of the reservoir portion also may be shaped to control the molten metal flow through the passages by increasing or decreasing the velocity of molten metal through the passage, and, in turn, control the kinetic energy of the molten metal exiting the passage to direct the molten metal shallow or deep into the casting pool as explained in more detail below.
Various aspects of the invention will be apparent from the following detailed description, drawings, and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described in more detail in reference to the accompanying drawings in which:

FIG. 1 a illustrates a cross-sectional end view of a portion of twin roll strip caster with an assembled metal delivery nozzle;

FIG. 1 b is an enlarged view of a portion of twin roll strip caster similar to FIG. 1 a except showing a trough with a concave upper surface;

FIG. 2 is a plan view of a segment of a metal delivery nozzle for use in the twin roll caster shown in FIG. 1 a;

FIG. 3 is a cross-sectional side view taken along line 3-3 of the segment of the metal delivery nozzle shown in FIG. 2;

FIG. 4 is a cross-sectional side view taken along line 4-4 of the segment of the metal delivery nozzle shown in FIG. 2;

FIG. 5 is a cross-sectional transverse taken along line 5-5 of the segment of the metal delivery nozzle shown in FIG. 2;

FIG. 6 is a cross-section transverse view of an alternative embodiment of the segment of a metal delivery nozzle shown in FIG. 5;

FIG. 7 is a cross-sectional transverse view of an alternative embodiment of the segment of a metal delivery nozzle shown in FIG. 5;

FIG. 8 is a cross-sectional side view similar to FIG. 3 of an alternative embodiment of a metal delivery nozzle for use in the twin roll caster shown in FIG. 1;

FIG. 9 is a plan view of a segment of an alternative metal delivery nozzle for use in the twin roll caster shown in FIG. 1;

FIG. 10 is a cross-sectional side view of a segment of another alternative metal delivery nozzle for use in the twin roll caster shown in FIG. 1;

DETAILED DESCRIPTION OF THE INVENTION

Referring to FIGS. la and lb, the metal strip casting apparatus 2 includes a metal delivery nozzle 10 located below a tundish 4 and above a pair of casting rolls 6. The casting rolls 6 are laterally positioned with a nip 9 formed between them. The tundish 4 receives molten metal from a ladle (not shown) and delivers the molten metal to a delivery nozzle 10. A shroud 5 may extend from the tundish 4 and into the delivery nozzle 10, for the purpose of transferring molten metal into the delivery nozzle 10. In the alternative, the tundish 4 may transfer molten metal to the delivery nozzle 10 via a hole in the bottom of the tundish 4. Below and around the lower portions of the delivery nozzle 10, a casting pool 8 having a surface 8A is formed and supported on the casting surfaces 7 of the casting rolls 6 adjacent the nip 9. The casting pool 8 is constrained at the ends of the casting rolls 6 and side dams or plates (not shown) positioned against the ends of the casting rolls. The side dams and their location in relation to the casting rolls 6 and the casting pool 8 are described, for example, in U.S. Pat. No. 7,556,084 granted Jul. 7, 2009, and in United States Publication No. 2009/0283240 published Nov. 19, 2009, which are incorporated herein by reference. The delivery nozzle 10 controls molten metal flow through passages 16 into the casting pool 8. Generally, the delivery nozzle 10 extends into the casting pool 8 during the casting campaign as shown in FIGS. 1 a and 1 b. Also, as shown in FIG. 1 a, gas control apparatus 3 is provided to maintain a gas seal 11 with the casting surfaces 7 of the casting rolls 6 and to maintain an inert atmosphere of nitrogen and/or argon above the casting pool 8 by blowing such gas through the passageways 12 in the gas control apparatus 3.
Referring to FIG. 2, the delivery nozzle 10 comprises two segments 13 (one shown), with each delivery nozzle segment 13 having opposing side walls 15 and an upward opening inner trough 14, which extend lengthwise along the segment 13 in the longitudinal direction of the delivery nozzle 10. In this embodiment, the side walls 15 are joined to the inner trough 14 to form shoulder portions 30, and the passages 16 are in the form of holes 31 extending through the shoulder portions 30 along each side of the inner trough 14. The molten metal flows from the inner trough 14 through the holes 31 to the side outlets 20. In this embodiment, the shoulder portions 30 provides the structural support to the delivery nozzle segment 13 when loaded with molten metal during a casting campaign. As a result, the flow of molten metal from the side outlets 20 into the casting pool 8 can be provided laterally more evenly along the delivery nozzle segment 13.
The pair of delivery nozzle segments 13 may be assembled lengthwise with the end walls 19, in abutting relation, and end walls 18 forming the ends of delivery nozzle 10. Alternatively, delivery nozzle 10 may comprise a single delivery nozzle segment 13, or more than two segments 13, that include all the features of, and effectively functions as the assembled pair of segments 13 as described herein. Each delivery nozzle segment 13 may be made of any refractory material, such as alumina graphite. As shown in FIG. 1, each delivery nozzle segment 13 includes mounting flanges 27 that extend outward from side walls 15, either continuously (as shown in FIG. 2) or, intermittently, as desired, to mount delivery nozzle segments 13 assembled forming the delivery nozzle 10 of the casting apparatus 2.
In operation, molten metal is poured through a shroud 5 into the inner trough 14 of mounted delivery nozzle segments 13. Several shrouds 5 may be provided along the length of the delivery nozzle segments 13. The molten metal flows from the inner trough 14 into and through passages 16 into the side outlets 20. The side outlets 20 direct the flow of molten metal to discharge the molten metal laterally into the casting pool 8 in the direction of the meniscus between the surface 8A of the casting pool 8 and the casting surfaces 7 of the casting rolls 6. Since the passages 16 and side outlets 20 extend along both sides of the delivery nozzle segments 13, a relatively uniform flow of molten metal can be provided along the length of the metal delivery nozzle segments 13. Also, note, as shown, in FIG. 3, the inner trough 14 of each delivery nozzle segment 13 may extend into the end portions 18 underneath a reservoir 24 (described below) to further extend the relatively uniform flow of molten metal into the casting pool 8 along the length of the segment 13.
Referring to FIGS. 2 and 5, the assembly of the reservoir 24 is shown at the end portion 18 of the delivery nozzle segment 13 adjacent the ends of the casting rolls 6. The region of casting pool 8 below the reservoir 24 at the end portion 18 near the intersection of the casting rolls 6 and the side dams is the area where skulls are more likely to form because of the different heat gradient adjacent a side dam. To compensate, molten metal is directed through first passages 22 and second passages 23 from the reservoir 24, which is positioned transverse to the end portion 18 of the delivery nozzle segment 13 as shown in FIGS. 2 and 5. The shape of the reservoir 24 is shown in FIGS. 2, 3, and 5, with a bottom portion 26 shaped to cause the molten metal to flow into first passages 22 and second passages 23. A weir 25 is also provided in the segment 13 to separate the flow of molten metal in the reservoir 24 providing a constant head while allowing the flow of molten metal from the inner trough 14 concurrently into the passages 16 in the main body of the metal delivery nozzle 10.
As shown in FIG. 5, the first passages 22 and second passages 23 are provided slanted to deliver the molten metal into this point area adjacent the side dams. The first passages 22 are adapted to deliver molten metal shallowly into the casting pool 8 adjacent the side dams, and the second passages 23 are adapted to deliver molten metal deeper into the casting pool 8 than the first passages 22 adjacent the side dams, while allowing shells to form on the casting surfaces 7 of the casting rolls 6 without substantial washing by the molten metal from first and second passages 22 and 23, respectively, during a casting campaign. The first passages 22 and the second passages 23 may be between 5 and 30 millimeters apart between near wall portions of the passages as shown in FIG. 5. The first passages 22 and the second passages 23 may also be substantially parallel. The first and second passages 22 and 23, respectively, may be between 7 to 12 millimeters in diameter, and the first and second passages may be of different diameter, as desired, to deliver the molten metal into the casting pool 8 at the desired location as the shells move through and are formed in the casting pool 8. Also, the first and second passages 22 and 23, respectively, may be provided in pairs on both sides of the side dams near the casting rolls as shown in FIG. 5.
Referring to FIG. 6, an alternative embodiment of the reservoir 24 of a delivery nozzle segment 13 is shown that is otherwise the same as that shown in FIG. 1 a. The first passages 22 and the second passages 23 are provided slanted to deliver the molten metal into the desired area adjacent the side dams. The first passages 22 are adapted to deliver molten metal shallowly into the casting pool 8 adjacent the side dams, and the second passages 23 are adapted to deliver molten metal deeper into the casting pool 8 than the first passages 22 adjacent the side dams, while allowing shells to form on the casting surfaces 7 of the casting rolls 6 without substantial washing by the molten metal from the first and second passages 22 and 23, respectively, during a casting campaign. In FIG. 6, the first passages 22 are shown having an entry port 35 and an exit port 36 and the second passages 23 are shown having an entry port 37 and an exit port 38. The first passages 22 are shaped so that the entry port 35 has a smaller diameter than the exit port 36. The exit port 36 having a larger diameter than the entry port 35 increases the cross-sectional area for the molten metal as it travels through the first passages 22 and, in turn, reduces the velocity of the molten metal. Thus, the kinetic energy of the molten metal exiting the first passages 22 at exit port 36 is reduced and the molten metal is directed into the shallow part of the casting pool 8 near the region adjacent the side dams, inhibiting the washing of shells from the casting roll surface 7, allowing the shells to form and develop during casting.
Alternatively or in addition, the second passages 23 are shaped with the passage 23 at entry port 37 having a larger diameter than the exit port 38. The exit port 38 having a smaller diameter than the entry port 37 reduces the cross-sectional area for the molten metal as it travels through the second passages 23 and causes the velocity of the molten metal to increase as it flows through the second passages 23. Thus, the kinetic energy of the molten metal exiting the second passages 23 at the exit port 38 is increased allowing the molten metal to travel deeper into the casting pool 8 adjacent the side dam as compared to the molten metal flow from the first passages 22. The molten metal is directed deeper into the casting pool 8 by the second passages 23 and inhibits the formation of skulls.
Referring to FIG. 7, an alternative embodiment of the reservoir 24 of the delivery nozzle segment 13 is shown that is otherwise the same as that shown in FIGS. 1 a, 1 b, and 5. The shape of the weir 25 allows the flow of molten metal into the reservoir 24 to impinge on the floor 27, and then flow outwardly and through passages 22 and 23, respectively, into the casting pool adjacent the side dams. The part 28 of the reservoir 24 between passages 22 and 23, respectively, and the outer portion 29 of the reservoir 24 are shaped to provide the desired flow and flow direction to the molten metal through first passages 22 shallowly into the casting pool 8 adjacent the side dams and through the second passages 23 adapted to deliver molten metal deeper into the casting pool 8 than the first passages 22 adjacent the side dams, while allowing shells to form on the casting surfaces 7 of the casting rolls 6 without substantial washing by the molten metal from first and second passages 22′ and 23′, respectively. This embodiment allows the ferrostatic head of molten metal in the reservoir 24 to be controlled and maintained and, in turn, provide more uniform flow adjacent the side dams.
Referring to FIG. 8, another alterative embodiment of the metal delivery nozzle is illustrated where the inner trough 14 of each delivery nozzle segment 13 does not extend into the end portions 18 underneath the reservoir 24. This embodiment does not provide relatively uniform flow of molten metal into the cast pool 8 to the end portion 18 of the segment 13. However, this embodiment may be desired because of simplicity in the making of the delivery nozzle 10.
Referring to FIG. 9, another alternative of the delivery nozzle 10 and segments thereof is illustrated. Partitions 17 extend between side walls 15 at spaced locations along each segment 13, and provide structural support for the segment 13 of the delivery nozzle 10 when loaded with molten metal during a casting campaign. Passages 16 are formed between the side walls 15 and the inner trough 14 as shown in FIGS. 1 a and 1 b. Passages 16 extend between partitions 17 or between a partition 17 and the end walls 18 or 19 along the length of the delivery nozzle segments 13. Passages 16 extend to side outlets 20 at the bottom portion 21 of the segment 13. The configuration of the reservoir portion 24 with the first passages 22 and the second passages 23 is the same as described above with reference to FIGS. 1 a, 1 b, and 5.
Referring to FIG. 10, each delivery nozzle segment 13 is assembled in two pieces, with one piece being the inner trough 14 and the bottom portion 21 as shown in FIG. 1 a. The other piece includes all of the other parts of the delivery nozzle segment 13 as described above with reference to FIGS. 1-5. The two pieces are assembled together by use of ceramic pins 32, which extend through holes on the side walls 15 and into or through holes in the side portions of the inner trough 14. The ceramic pins provide structural support for the segments 13 and the assembled delivery nozzle 10 when the delivery nozzle 10 is loaded with molten metal during a casting campaign. The configuration of the reservoir 24 with the first passages 22 and the second passages 23 is the same as described above with reference to FIGS. 1 a, 1 b, and 5.
It should be understood that the above described apparatus and method of casting thin strip are the presently contemplated best modes of embodying the invention. Other details in the assembly and operation of the casting method and metal delivery nozzle therefor is described by reference to pending application Ser. No. 12/403,876, filed Mar. 13, 2009, which is incorporated herein by reference. It is to be understood that these and other embodiments may be made, and performed, within the scope of the following claims. In each embodiment of the delivery nozzle, the nozzle insert dissipates a substantial part of the kinetic energy built up in the molten metal by reason of movement through the delivery system from the metal distributor to the delivery nozzle, and the resistance to movement of the molten metal from the inner trough through the passages to the side outlets further reducing the kinetic energy in the molten metal from the molten metal before reaching the casting pool. As a result, a more uniform and more quiescent flow of molten metal is provided to the casting pool for the formation of the cast strip.
While the principle and mode of operation of this invention have been explained and illustrated with regard to particular embodiments, it must be understood, however, that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.

Claims

1. A method of casting metal strip comprising:

(a) assembling a pair of casting rolls laterally disposed to form a nip between them and between side dams adapted to maintain a molten metal pool supported by the casting rolls,

(b) assembling an elongated metal delivery nozzle extending along and above the nip with at least one segment having a main portion adapted to deliver molten metal in the casting pool along the metal delivery nozzle and an end portion adjacent side dams having a reservoir portion having first and second passages adapted to deliver molten metal into a molten metal pool adjacent the side dams while shells are forming on the casting rolls, the first passages adapted to deliver molten metal shallowly into the casting pool adjacent the side dams and the second passages adapted to deliver molten metal deeper into the casting pool than the first passages adjacent the side dams,

(c) introducing molten metal through the elongated metal delivery nozzle to form a casting pool of molten metal supported on the casting rolls above the nip, and through the first and second passages in the reservoir portion in the end portions into the casting pool, and

(d) counter rotating the casting rolls to deliver cast strip downwardly from the nip.

2. The method of casting metal strip as claimed in claim 1 where the first and second passages of the reservoir portion are substantially parallel.

3. The method of casting metal strip as claimed in claim 1 where the first and second passages of the reservoir portion are between 5 and 30 millimeters apart.

4. The method of casting metal strip as claimed in claim 1 where the first and second passages of the reservoir portion are shaped to control the velocity of molten metal through the passages.

5. The method of casting metal strip as claimed in claim 1 where the reservoir portion in the end portion of each segment has longitudinally extending weirs adjacent the side walls of the inner trough adapted to allow molten metal to flow over the weirs between the reservoir portion and the main portion.

6. The method of casting metal strip as claimed in claim 1 where dual first and second passages are provided in each reservoir portion of the metal delivery nozzle.

7. The method of casting metal strip as claimed in claim 6 where the first and second passages of the reservoir portion are substantially parallel.

8. The method of casting metal strip as claimed in claim 6 where the first and second passages of the reservoir portion are between 5 and 30 millimeters apart.

9. The method of casting metal strip as claimed in claim 6 where the first and second passages of the reservoir portion are shaped to control the velocity of molten metal through the passages.

10. The method of casting metal strip as claimed in claim 6 where the reservoir portion in the end portion of each segment has longitudinally extending weirs adjacent the side walls of the inner trough adapted to allow molten metal to flow over the weirs between the reservoir portion and the main portion of the delivery nozzle.

11. A metal delivery apparatus for casting metal strip comprising at least one elongated segment having a main portion adapted to deliver molten metal in the casting pool along the metal delivery nozzle and an end portion adjacent side dams having a reservoir portion having first and second passages adapted to deliver molten metal into a molten metal pool adjacent the side dams while shells form on the casting rolls, the first passages adapted to deliver molten metal shallowly into the casting pool adjacent the side dams and the second passages adapted to deliver molten metal deeper into the casting pool than the first passages adjacent the side dams.

12. The metal delivery apparatus for casting metal as claimed in claim 11 where the first and second passages of the reservoir portion are substantially parallel.

13. The metal delivery apparatus for casting metal strip as claimed in claim 11 where the first and second passages of the reservoir portion are between 5 and 30 millimeters apart.

14. The metal delivery apparatus for casting metal strip as claimed in claim 11 where the first and second passages of the reservoir portion are shaped to control the velocity of molten metal through the passages.

15. The metal delivery apparatus for casting metal strip as claimed in claim 11 where the reservoir portion in the end portion of each segment has longitudinally extending weirs adjacent the side walls of the inner trough adapted to allow molten metal to flow over the weirs between the reservoir portion and the main portion of the metal delivery apparatus.

16. The metal delivery apparatus for casting metal strip as claimed in claim 11 where dual first and second passages are provided in each reservoir portion of the metal delivery nozzle.

17. The metal delivery apparatus for casting metal strip as claimed in claim 16 where the first and second passages of the reservoir portion are substantially parallel.

18. The metal delivery apparatus for casting metal strip as claimed in claim 16 where the first and second passages of the reservoir portion are between 5 and 30 millimeters apart.

19. The metal delivery apparatus for casting metal strip as claimed in claim 16 where the first and second passages of the reservoir portion are shaped to control the velocity of molten metal through the passages.

20. The metal delivery apparatus for casting metal strip as claimed in claim 16 where the reservoir portion in the end portion of each segment has longitudinally extending weirs adjacent the side walls of the inner trough adapted to allow molten metal to flow over the weirs between the reservoir portion and the main portion of the delivery apparatus.