EP0313052B1

EP0313052B1 - Tundish for horizontal continuous casting

Info

Publication number: EP0313052B1
Application number: EP88117499A
Authority: EP
Inventors: Masahiro C/O Patent & License And Tsuru; Shunji C/O Patent & License And Ootomo; Tadayoshi C/O Patent & License And Shinozaki; Yoshitaka C/O Patent & License And Ishizuka; Tatsuo C/O Patent & License And Saeki; Kenichi C/O Patent & License And Kobuchi; Shinichi C/O Patent & License And Muto
Original assignee: NKK Corp
Current assignee: JFE Engineering Corp
Priority date: 1987-10-21
Filing date: 1988-10-20
Publication date: 1991-06-12
Anticipated expiration: 2008-10-20
Also published as: JPH0575499B2; KR890006326A; JPH01107951A; EP0313052A1; KR920000515B1; ES2022570B3

Description

The present invention relates to a tundish for horizontal continuous casting, and more particularly, to a discharging mechanism for molten metal remaining in a tundish at the end of the horizontal continuous casting.
From FR-A-2 148 618 a continuous horizontal casting apparatus is known which is provided with a mold mounted horizontally at a lower portion of a first side wall of a tundish. The mold is adjoining to the tundish through a feed nozzle in the first side wall. A billet is pulled out through the mold in the horizontal direction and thus the billet is continuously cast. At the end of the horizontal continuous casting, molten metal remaining in the tundish is discharged through a discharging bore provided opposite the feed nozzle at the bottom of the tundish in a second side wall thereof by removing a plug provided in and mating with the discharging bore.
In US-A- 4 298 147, a discharging mechanism for molten metal and slag is disclosed, which comprises:

a tundish having at least one feed nozzle;
a discharging nozzle having a discharging bore flaring outwardly and downwardly, for discharging molten metal and slag remaining in said tundish, said discharging nozzle being fixed to a bottom wall of said tundish substantially in the center of said tundish;
a plug mating with said discharging bore and being releasedly inserted from the outside of said bottom wall into said discharging bore, so as to be able to be fitted to and taken out of said discharging bore and;
a plug fitting fixed to the lower end of said plug; and
a engaging means, connected to said plug fitting, for selectively inserting said plug into said discharging bore, holding said plug in said discharging bore and withdrawing said plug from said discharging bore.

In the above mentioned prior art, however, molten metal flows outwardly in the direction of the feed nozzle, so that the temperature of the side wall opposite the side wall having the feed nozzle fixed thereto and a bottom wall portion near the former side wall is lowered, and the molten metal solidifies and adheres to the opposite side wall and the bottom wall. Therefore, the known discharging methods have been disadvantageous in that the molten metal does not flow out even if the plug is pulled out, or that the plug is hard to pull out because of being torn off.
It is an object of the present invention to provide a constitution of a tundish for a horizontal continuous casting capable of easily discharging molten metal remaining in the tundish.
In accordance with the present invention, a tundish for a horizontal continuous casting is provided comprising:

a feed nozzle being fixed to a first side wall of a tundish and supplying molten metal to a horizontal mold;
a discharging nozzle fixed to a confronting position at a lower portion of a second side wall of said tundish opposite said first side wall and having a discharging bore flaring outwardly out of said tundish, for discharging a part of the molten metal remaining in said tundish;
a plug mating with said discharging bore and being releasedly inserted from the outside of said tundish into said discharging bore, so as to be capable of being fitted into and taken out of the discharging bore; and
a runner pipe having an opening through which molten metal flows into said runner pipe from said tundish above said runner pipe, the runner pipe connecting said feed nozzle to said discharging nozzle.

Other features and advantages of the present invention will be apparent from the detailed description to follow, taken in conjunction with the accompanying drawings wherein:

Fig. 1 is a cross sectional view illustrating a tundish for a horizontal continuous casting of the present invention;
Fig. 2 is a vertical section view of the tundish for the horizontal continuous casting, taken on line I-I′ of Fig. 1.; and
Fig. 3 is a plan view of the tundish for the horizontal continuous casting, taken on line II-II′ of Fig 1.

A feed nozzle 18 is fixed at a lower portion of a first side wall 12a of a tundish 10, supplying molten metal 14 to a horizontal mold 16. A discharging nozzle 26 is fixed in a confronting position at a lower portion of a second side wall 12b of the tundish on the opposite side of the first side wall, and is used for discharging a part of the molten metal remaining in the tundish 10. The discharging nozzle 26 has a discharging bore 28 which flares outwardly through the second side wall. A plug 30 mating with the discharging bore is inserted into the discharging bore 28 from the outside of tundish 10 in a releasable manner so as to be able to be fitted to or taken out of the discharging bore. A runner pipe 22 is arranged at the bottom wall 20 of tundish 10, and comprises an opening 24 through which molten metal 14 flows into the runner pipe 22 from the tundish above the runner pipe and which runner pipe connects the feed nozzle 18 with the discharging nozzle 26.
The runner pipe 22 is made from refractory. The refractory is preferably selected as any one from the group consisting of zircon, magnesia, alumina-graphite and magnesia-graphite which have property of corrosion resistance and spalling resistance against molten metal 14.
It is preferable that the diameter D₁ of a circle corresponding to the sectional area of the runner pipe is 0.5 to 2.0 of diameter D of a circle corresponding to the sectional area of the mold 16, provided, however, that D₁ is preferably 80 mm or more, where a diameter of circle corresponding to the sectional area equals a diameter when the sectional shape of the runner pipe is a circle and it equals the length computed by the formula "(2/√π)×(a length of a side)" when the sectional shape of the runner pipe is a square.
The opening 24 of the runner pipe 22 is preferably arranged close to the discharging nozzle 26. The distance from the discharging nozzle 26 to the center of the opening 24 is preferably determined to be the diameter D₁ of the runner pipe 22 or less.
The diameter D₂ of a circle corresponding to the sectional area of the opening 24 is preferably 0.7 to 1.2 of the diameter D₁ of a circle corresponding to the sectional area of the runner pipe 22, provided, however, that the minimum dimension of the diameter D₂ is preferably 80 mm or more.
The plug 30 mating with the discharging bore 28 is made from refractory. The refractory is preferably selected as any one from the group consisting of zircon, magnesia, alumina-graphite and magnesia-graphite which have property of corrosion resistance and spalling resistance against molten metal 14.
Next, an actual operation of a tundish of the present invention will be described. The inside of tundish 10 is preheated by fuel to 1200 to 1300°C before molten metal 14 is charged. After the preheting of the tundish, molten metal 14 is poured onto the bottom wall 20 of the tundish 10 from a ladle (not shown). The molten metal introduced into the tundish flows into the runner pipe 22 through the opening 24 and the runner pipe fills with the molten metal 14. When molten the metal 14 increases to a certain level inside the tundish, a drawer (not shown) set in the mold 16 begins to work and a billet to be made from the molten metal is drawn out. Molten metal 14 in the runner pipe 22 moves into the mold 16 through the feed nozzle 18. Since molten metal 14 in the tundish 10 flows close to discharging bore 28, the second side wall 12b and a portion of the bottom wall 20 neighboring with a lower portion of the second side wall are kept at a high temperature and there is no fear that molten metal 14 solidifies and adheres to walls of the tundish.
Consequently, when the molten metal 14 is as high as an upper side level of runner pipe 22 at the end of the casting operation, the molten metal 14 flows out promptly through the discharging bore 28 upon the withdrawal of the plug 30 inserted in the discharging nozzle 26. A comparison of the ratio of success in discharging molten metal 14 according to the present invention with that according to a prior art tundish is shown in Table 1. When a tundish of the present invention was used, molten metal 14 flowed out successfully all out of 25 times of the discharging upon the withdrawal of the plug 30. The ratio of success was 100%. But, when a prior art tundish was used, the molten metal failed to be discharged 8 of 37 times of the operation upon the withdrawal of the plug 30. Thus, the present invention improves greatly the success ratio of discharging molten metal at the end of the horizontal continuous casting process.

Claims

1. A tundish for horizontal continuous casting having a feed nozzle (18) being fixed to a first side wall (12a) of a tundish (10) and supplying molten metal (14) to a horizontal mold (16), comprising:

a discharging nozzle (26) fixed in a confronting position at a lower portion of a second side wall (12b) of the tundish (10) opposite the first side wall (12a) and having a discharging bore (28) flaring outwardly out of the tundish (10), for discharging a part of the molten metal (14) remaining in the tundish (10);

a plug (30) mating with the discharging bore (28) and being releasably inserted from the outside of the tundish (10) into said discharging bore (28), so as to be capable of being fitted into and taken out of the discharging bore (28), characterized by

a runner pipe (22) having an opening (24) through which molten metal (14) flows into the runner pipe (22) from the tundish (10) above said runner pipe (22), the runner pipe (22) connecting the feed nozzle (18) to the discharging nozzle (26).

2. The tundish of claim 1, characterized in that the opening (24) of the runner pipe (22) is arranged close by the discharging bore (28).

3. The tundish of claim 1, characterized in that the runner pipe (22) has a circular cross-section of diameter D₁ and the opening (24) is circular and has a diameter (D₂) and that the diameter D₂ is 0.7 to 1.2 times the diameter D₁, wherein the diameter D₂ is at least 80 mm.

4. The tundish of claim 1, characterized in that the runner pipe (22) has a circular cross-section of diameter D₁ and the mold (16) has a circular cross-section of diameter D and that the diameter D₁ is 0.5 to 2.0 times diameter D, wherein the diameter D₁ is at least 80 mm.

5. The tundish of claim 1, characterized in that the runner pipe (22) is made from any one selected from the group consisting of zircon, magnesia, alumina-graphite and magnesia-graphite.

6. The tundish of claim 1, characterized in that the plug (30) is made from any one selected from the group consisting of zircon, magnesia, alumina-graphite and magnesia-graphite.