APPARATUS FOR POURING MOLTEN METAL

Abstract: Apparatus for pouring molten metal into a continuous casting machine of moving mould type comprises a tundish car (10) which supports a tundish (9) and a tundish nozzle (11) which, in use, extends into the mould cavity of the casing machine. The tundish (9) includes an outlet portion (8) which is not connected to the tundish nozzle (11) but which defines a passage (13) communicating with the passage (13) within the tundish nozzle (11). Springs (16) connect the tundish car (10) and the tundish (9) and urge the downstream end of the outlet portion (8) into direct engagement with the upstream end of the tundish nozzle (11) or into indirect engagement with it via one or more intermediate members (19,20,21).

Description: The present invention relates to apparatus for pouring molten metal into a moving mould continuous casting machine. Figure 1 is a diagrammatic side elevation of a conventional moving-mould continuous casting machine comprising a plurality of mould blocks 1 connected to form two endless tracks 2 and 2′. These tracks are disposed one above the other with one run of each track cooperating to define a continuous mould cavity between them. In use, the mould assemblies or tracks 2 and 2′ are driven by drive wheels 3 and 3′ in the directions indicated by the arrows 4 and 4′ and molten metal is poured into the mould cavity at one end through a tundish nozzle 6 extending from a tundish 5 and the cast strand 7 is withdrawn from the other end of the mould cavity, as indicated by the arrow. In order to prevent leakage of molten metal in machines of the type described above, the gap between the tundish nozzle 6 in the mould cavity and the mould blocks 1 defining the mould cavity must be maintained at a predetermined small value with a high degree of accuracy. To this end, a tundish nozzle aligning system as shown in Figures 2 to 5 is conventionally used. In these figures, Figure 2 is a side elevation of the conventional aligning system; Figure 3 is a view in the direction of the arrow III in Figure 2; Figure 4 is a sectional view along the line IV-IV in Figure 2; and Figure 5 is a sectional view of the line VV in Figure 2. In this system the vertical position and the angle of inclination of the nozzle can be adjusted by operating handle wheels 25 which are operatively connected to jacks 24 mounted on a tundish-supporting stand 28. The horizontal position of the nozzle 6 can be adjusted by moving a jack stand 29 located below the tundish-supporting stand 28 by operating push bolts 26 and draw bolts 27, as shown in Figure 4. As best shown in Figure 5, the rotational alignment (inclination in a plane perpendicular to the nozzle axis) of the nozzle can be adjusted by adjusting nuts 33 of specially designed bolts 32 which are pivotally connected to a car frame 30 by pivot pins 31. However, this tundish-nozzle aligning system is not always effective in keeping the gap between the nozzle and mould blocks at a predetermined small value. Thus, high-temperature molten metal poured into the tundish 5 may cause deformation of it resulting in displacement of the tundish nozzle 6 in any direction and failure to maintain the predetermined clearance. As a result, the tundish nozzle 6 may contact the moulds 1 with a substantial pressure whereby the nozzle 6 and the moulds 1 become non-uniformly worn and damaged. DE-A-3311090, on which the precharacterising portion of claim 1 is based, discloses apparatus for pouring molten metal comprising a tundish which is positioned on a tundish car and is connected to an outlet portion which communicates with a separate pouring nozzle supported by the tundish car. It is the object of the present invention to over come the above and other problems encountered in conventional casting machines of the type described above and, in particular to provide an apparatus for pouring molten metal of the type referred to above in which the adverse effects of thermal deformation of the tundish are eliminated so that a predetermined gap between the tundish nozzle and the mould blocks can be maintained, thereby preventing damage to the tundish nozzle and the endless tracks of mould blocks. According to the present invention apparatus for pouring molten metal into a continuous casting machine, e.g. of moving mould type, comprises a tundish car which supports a tundish and a tundish nozzle which, in use, extends into the mould cavity of the casting machine, the tundish including an outlet portion which is not connected to the tundish nozzle but which defines a passage communicating with the passage within the tundish nozzle and is characterised in that the tundish car supports the tundish nozzle and that biasing means are provided which urge the downstream end of the outlet portion into direct or indirect engagement with the upstream end of the tundish nozzle. Thus in the apparatus of the present invention, the tundish nozzle is not connected to the tundish and is thus not subject to movement or deformation caused by movement or deformation of the tundish. Instead, the tundish nozzle is independent of the tundish and carried by the tundish car and the outlet portion of the tundish is urged into engagement with the tundish nozzle by biasing means. In use, slight movement or distortion of the tundish and thus of the outlet portion is accommodated by relative movement at the engaging surfaces of the outlet portion and the tundish nozzle and does not result in movement of the tundish nozzles whereby the clearance between the tundish nozzle and the size of the mould cavity may be maintained substantially constant at all times. The biasing means preferably comprises one or more springs and these preferably connect the tundish car and the tundish. The outlet member may engage the tundish nozzle directly or alternatively it may engage it indirectly with the inter postition of one or more intermediate members between the tundish nozzle and the outlet portion which permit relative movement therebetween. In one embodiment there is an intermediate member situated between the outlet portion and the tundish nozzle and defining a passage which connects the passages in the outlet portion and the tundish nozzle, at least one end of the intermediate member being curved, preferably part-spherical, and in sealing engagement with a correspondingly curved surface on the outlet portion and/or the tundish nozzle. In an alternative embodiment, there are two intermediate members situated between the outlet portion and the tundish nozzle and two or optionally more of the pairs of engaging surfaces of the outlet portion and the first intermediate member, the first and second intermediate members and the second intermediate members and the tundish nozzle are complementarily curved. The two pairs of curved surfaces may be of part-cylindrical shape with the axis of the two pairs being offset by 90° whereby each pair of curved surfaces can permit relative angular movement the outlet portion and the tundish nozzle in one plane. The present invention also embraces a continuous casting machine of moving mould type per se of the type comprising a variety of mould blocks connected together to form two endless tracks, the two tracks co-operating to define a mould cavity, which includes apparatus for pouring metal of the type referred to above with the tundish nozzle extending into one end of the mould cavity. Further features and details of the present invention will become apparent from the following description of certain preferred embodiments thereof which is shown by way of example with reference to Figures 6 to 10 of the accompanying drawings, in which: Figure 6 is a diagrammatic perspective view of a first embodiment of the present invention; Figure 7 is a scrap sectional view illustrating the joint between the molten-metal outlet portion and the tundish nozzle of the embodiment of Figure 6; Figure 8 is a view similar to Figure 7 of a second embodiment of the present invention; Figure 9 is a view similar to Figure 7 of a third embodiment of the present invention; and Figure 10 is a view in the direction of the arrow X in Figure 9. Figures 6 and 7 show tundish 9 with a short molten-metal pouring outlet portion 8 mounted on a tundish car frame 10 to which a tundish nozzle 11 is secured in alignment with the outlet portion by bolts 12 or the like. The outlet portion 8 and the tundish nozzle 11 are composed of a refractory material 14 and have a coaxially extending pouring bore 13 and are surrounded by a steel shell or cladding 15. The downstream end of the outlet portion 8 is firmly pushed by springs 16 or the like between the tundish car frame 10 and the tundish 9 into abutment with the refractory member 14 of the tundish nozzle 11 to form a tight seal between the outlet portion 8 of the tundish 9 and the tundish nozzle 11. In use, the car frame 10 is located by alignment means (not shown) such that the tundish nozzle 11 is located in the desired position with respect to the continuous casting machine. The car frame 10 which supports the tundish 9 is not directly thermally affected by the molten metal so that thermal deformation of the car frame 10 is negligible. It follows therefore that the tundish nozzle 11, which is mounted on the tundish car frame 10 which is substantially free from thermal deformations, can be maintained at a predetermined position with respect to the continuous casting machine. Even when molten metal flowing into the tundish 9 causes thermal deformation of the tundish and consequently displacement of its outlet portion 8, the gap between the tundish nozzle 11 and the mould blocks 1 may be maintained since such displacement of the outlet portion 8, which is independent of the nozzle 11, leads to slippage of the outlet portion 8 itself with respect to the tundish nozzle in the abutment plane 17 rather than displacement of the tundish nozzle 11. Leakage of molten metal at the abutment of the outlet portion and the tundish nozzle is prevented since the outlet portion 8 is pressed against the refractory member 14 of the tundish nozzle 11 by biasing means such as the springs 16 or the like between the tundish car frame 19 and the tundish 9. In the construction described above, no molten metal will leak at the abutment 17 when relative movement of the outlet portion 8 occurs. However, if the axis of the outlet portion 8 were significantly inclined to the axis of the tundish nozzle 11, a gap would be produced which would result in a gap through which molten metal could leak. If the apparatus and casting parameters are such that such a gap could appear, means should be provided to prevent the leakage of metal occurring. The second embodiment of the present invention shown in Figure 8 is equipped with means to prevent such leakage of molten metal. Interposed between the outlet portion 8 and the tundish nozzle 11 is an intermediate member 19 comprising a refractory member 14 having a coaxial pouring bore 13 and a steel shell 15 surrounding the member 14. The intermediate member 19 has a convex part-spherical surface 18 formed at its upstream end. The downstream end of the outlet portion 8 is formed with a corresponding concave part-spherical surface 18′ which mates snugly with the convex surface 18. The downstream end of the intermediate member 19 is planar and is in flush engagement with the tundish nozzle 11. In the second embodiment, even if the outlet potion 8 should be deformed such that its axis is inclined to the axis of the tundish nozzle 11, no gap is formed since the angular misalignment is accommodated by the part-spherical surfaces 18 and 18′ and thus no leakage of molten metal can occur. It will be appreciated that a modified embodiment is equally possible in which the intermediate member 19 may have a concave part-cylindrical upstream end while the downstream end of the outlet portion 8 is convex of part-spherical shape. Alternatively, the complementary convex and concave part-spherical surfaces may be provided on opposed ends of the intermediate member 19 and the tundish nozzle 11. In the third embodiment of the present invention illustrated in Figures 9 and 10, first and second intermediate members 20 and 21 are interposed between the outlet portion 8 and the tundish nozzle 11. The upstream end of the upstream intermediate member 20 has a convex semi-cylindrical surface 22 and the downstream end of the outlet portion 8 has a concave semi-cylindrical surface 22′ which mates snugly with it. Furthermore, the downstream end of the intermediate member 29 has a convex semi-cylindrical surface 23 whose access is offset by 90° from that of the semi-cylindrical surface 22 while the upstream end of the intermediate member 21 has a corresponding concave semi-cylindrical surface 23′ which mates snugly with it. The downstream end of the intermediate member 21 is flat and engages the upstream end of the tundish nozzle over an abutment plane 17. In the third embodiment, relative movement at the flat abutment 17 and mating convex and concave surfaces 22, 22, 23 and 23′ will absorb movement and deformation of the outlet portion 8 in every direction without leakage of molten metal. As in the second embodiment the position of the various convex, concave and flat surfaces may of course be varied.

Claims: 1. Apparatus for pouring molten metal into a continous casting machine comprising a tundish car (10) which supports a tundish (9) and a tundish nozzle (11) which, in use, extends into the mould cavity of the casting machine, the tundish (9) including an outlet portion (8) which is not connected to the tundish nozzle (11) but which defines a passage (13) communicating with the passage (13) within the tundish nozzle (11), characterised in that the tundish car (10) supports the tundish nozzle (11) and that biasing means (16) are provided which urge the downstream end of the outlet portion (8) into direct or indirect engagement with the upstream end of the tundish nozzle (11). 2. Apparatus as claimed in claim 1 characterised in that the biasing means comprises one or more springs (16) which connect the tundish car (10) and the tundish (9). 3. Apparatus as claimed in claim 1 or claim 2 characterised by one or more intermediate members (19, 20, 21) between the tundish nozzle (11) and outlet portion (8) which permit relative movement therebetween. 4. Apparatus as claimed in any one of claims 1 to 3 characterised by an intermediate member (19) situated between the outlet portion (8) and the tundish nozzle (11) and defining a passage (13) which connects the passages (13) in the outlet portion (8) and the tundish nozzle (11), at least one end of the intermediate member (19) being curved and in sealing engagement with a correspondingly shaped surface on the outlet portion (8) and/or the tundish nozzle (1). 5. Apparatus as claimed in Claim 4 characterised in that the curved surfaces (18, 18′) are part-spherical. 6. Apparatus as claimed in any one of Claims 1 to 3 characterised by two intermediate members (20, 21) situated between the outlet portion (8) and the tundish nozzle (11), at least two (22, 22′; 23, 23′) of the pairs of engaging surfaces of the outlet portion (8) and the first intermediate member (20), the first and second intermediate members (20, 21) and the second intermediate member (21) and the tundish nozzle (11) being complementarily curved. 7. Apparatus as claimed in Claim 6 characterised in that the two pairs of curved surfaces (22, 22′; 23, 23′) are of part-cylindrical shape, the axes of the two pairs being offset by 90°. 8. A continuous casting machine comprising a plurality of mould blocks connected together to form two endless tracks (2, 2′), the two tracks cooperating to define a mould cavity, characterised by apparatus for pouring metal as claimed in any of the preceding claims, the tundish nozzle (11) of which extends into one end of the mould cavity.

Inventors: HASEBE, NOBUHISA, OSADA, SHIRO, OZEKI, AKICHIKA, SATO, HISASHI, TAKAHASHI, SHUZO, TSUCHIDA, YUTAKA
Applicants: ISHIKAWAJIMA-HARIMA  JUKOGYO KABUSHIKI KAISHA, NIPPON KOKAN KABUSHIKI KAISHA
Application year: 1988
Main classification: B22D11
IPC codes: B22D11