ENDLESS TRACK TYPE CONTINUOUS CASTING MACHINE

Abstract: A continuous casting machine includes a plurality of mould blocks (1) and associated carriers (14) connected to form two endless tracks (2) arranged one above the other. The endless tracks (2) have respective substantially horizontal runs which cooperate to define a mould cavity (3) and, in use, are moved in the same direction. Each endless track (2) has a run (11) which extends substantially vertically from the upstream end of the mould cavity (3) and a further run (9) which is inclined to the horizontal and extends in the direction of movement of the said horizontal runs from the downstream end of the mould cavity (3). Power transmission means including gears (26 and 29) in mesh with a rack on the carriers (14) in the vertical run (11) and the inclined run (9) of the upper endless track (2) is arranged to convert a proportion of the downward force due to the weight of the mould blocks (1) and carriers (14) in the vertical run (11) into a force pushing the mould blocks (1) and carriers (14) up the inclined run (9).

Description: The present invention relates to a continuous casting machine of endless track type and relates to that type of such machine which includes a plurality of mould blocks and associated carriers connected to form two endless tracks arranged one above the other, the endless tracks having respective substantially horizontal runs which cooperate to define a mould cavity and, in use, are moved in the same direction, each endless track having a run which extends substantially vertically from the upstream end of the mould cavity and a further run which is inclined to the horizontal and extends in the direction of movement of the said runs from the downstream end of the mould cavity. Figure 1 is a diagrammatic side elevation of a conventional endless track type continuous casting machine. Such a machine is disclosed in JP-A-60240356. A plurality of mould blocks 1 are interconnected to form two mould assemblies 2 in the form of endless tracks. The two mould assemblies 2 are disposed one above the other with respective runs adjacent to one another to define a mould cavity 3. A tundish nozzle 5 extends from the bottom of a tundish 4 into the upstream end of the mould cavity 3. In use, melt is poured into the tundish 4 and is supplied through the tundish nozzle 5 into the mould cavity 3 defined by the upper and lower mould assemblies 2 which are moved in the same direction by respective driving and idle rolls 6 and 7. The melt is cooled by the mould blocks to solidify into a casting 8 which is discharged from the downstream end of the continuous casting machine. In the continuous casting machine described above, the cooling zone of each mould assembly 2 is constituted by the return path of the mould assembly 2, ie. the path of the mould blocks between the downstream and upstream end of the mould cavity, which is relatively short so that there is a tendency for the mould blocks 1 not to be sufficiently cooled by the time they return to the upstream end of the mould cavity 3. This lack of cooling can result in insufficient solidification of the molten metal and this in failure of the continuous casting operation. A solution to this problem is proposed in JP-B-4626628 which discloses a continuous casting machine as shown in Figures 2 to 6 in which Figure 2 is a view similar to Figure 1, Figures 3 and 4 are sectional views on the lines III-III and IV-IV, respectively in Figure 2, Figure 5 is a detailed view of a mould block and its carrier of the machine of Figures 2 to 4 and Figure 6 is a schematic view illustrating the arrangements of the mould blocks and their carriers. This casting machine is of the generic type referred to above and again comprises upper and lower mould assemblies 2, each comprising a plurality of mould blocks 1 interconnected in the form of an endless track, disposed in vertically opposing relationship to define the mould cavity 3. Each endless track defines relatively long inclined and horizontal cooling zones 9 and 10 between the downstream and upstream ends of the mould cavity 3, as shown in Figure 2. Each mould assembly 2 is driven by gears 12 connected to be driven by a mould assembly driving system and is braked at the downstream portion of the mould cavity 3 by a gear 13. Such braking of the mould assemblies 2 contributes to preventing melt from leaking through gaps between the mould blocks 1 in the runs of the endless tracks defining the mould cavity 3. As shown in Figures 3 to 5, each mould block 1 is securely joined to a carrier 14 which on each side has a rack 15 in mesh with the gears 12 and 13 and two wheels 16 for engagement with the gear 12′, as shown in Figure 5. One of the two wheels 16 is directly supported by the carrier 14 via a shaft 17 while the other wheel 16 is indirectly supported thereby via a shaft 17 received in a bearing box 19 which is fitted into a groove 18 defined in the carrier 14 for sliding movement in the direction of movement of the mould blocks 1 and which is also supported by an adjacent carrier. More specifically, the shaft 17 which is directly supported by the carrier 14 is provided with a bearing box 19 which is of the same construction as the bearing box 19 described above and which is slidably fitted into a groove 18 of an adjacent carrier 14 in front of it or behind it. The shaft 17 which is supported via the bearing box 19 by the carrier 14 is directly supported on an adjacent carrier 14 in front of it or behind it. Thus, the carriers 14 are sequentially interconnected so that the mould blocks 1 are interconnected in the form of an endless track as described above. Each frame 20 is formed with an endless groove 21 in which the wheels 16 are rotatably received. The endless track mould assemblies 2 are driven by motors 22 and provided with brakes 23. The side surfaces of the mould cavity are afforded by side dam blocks interposed between the upper and lower opposing mould blocks 1 and adapted to move in synchronism with the mould blocks. In operation, the motors 22 are energised to drive the mould blocks 1 through the gears 12 and the racks 15 and the side dam blocks 24 are also driven in synchronism with their associated mould blocks 1. The brakes 23 are also energised to brake the mould assemblies 2 through the gears 13 and the racks 15 such that no gaps are produced between adjacent mould blocks 1 defining the mould cavity 3. In this case, the wheels 16 roll in the grooves 21 so that the mould assemblies 2 are moved smoothly. Melt in the tundish 4 is supplied through the tundish nozzle 5 into the mould cavity 3 and is cooled by the mould blocks to solidify into a casting 8 which is subsequently discharged out of the casting machine. The mould assemblies 2 are cooled by any suitable means in the cooling zones 9 and 10 and the cooled mould blocks return to the upstream end of the mould cavity 3. The continuous casting machine shown in Figures 2 to 6 has relatively long cooling zones 9 and 10 so that the mould blocks are satisfactorily cooled by the time they return to the upstream end of the mould cavity 3 and consequently the continuous casting operation is not adversely affected. The continuous casting machine described above has, however, a problem in that the upper horizontal moulding surface of the mould cavity 3 tends to be inclined downwardly since the upper mould assembly 2 has the inclined cooling zone 9 and a vertical preheating and drying zone 11, both of which are relatively long and heavy. In addition, the fact that the adjacent carriers 14 are spaced apart in order to absorb thermal expansion and the adjacent mould blocks are in close contact with each other to prevent leakage of melt results in the downward force (driving force and weight) of the vertical run of the mould assembly 2 being transmitted as a pressure through the contact surfaces of the mould blocks and consequently the mould blocks may be damaged if this pressure becomes too large. Furthermore, it is difficult to maintain the desired degree of flatness or alignment of the mould blocks 1 and the carriers 14 since they tend to become inclined due to the fact that the mould blocks are subjected to a moment M = FH. where F is the pressing force exerted when the mould blocks are driven and H is the height from the points of action of the pressing force between adjacent carriers 14 to the wheels 16 (see Figure 6) and there is a gap G between the wheels 16 and the top of the grooves 18 as shown in Figures 3 and 4. Due to these problems, it is feared that the desired cross-sectional configuration and size of the mould cavity 3 cannot be reliably maintained. It is thus a primary object of the present invention to prevent distortions in the cross-sectional configuration and size of the mould cavity due to the weight of the mould blocks and their carriers. According to the present invention a continuous casting machine of the type referred to above is characterised by power transmission means in engagement with the carriers of the mould blocks in the vertical run and the inclined run of the upper endless track and arranged to convert a proportion of the downward force due to the weight of the mould blocks and carriers in the vertical run into a force pushing the mould block and carriers up the inclined run. Thus in the casting machine in accordance with the present invention the weight of the mould blocks and carriers in the vertical run of the upper endless track is not permitted to act on the mould blocks and carriers in the horizontal track which partially defines the mould cavity thereby impairing their alignment and potentially damaging them but instead a proportion of the force due to their weight is transmitted directly to the inclined run of the upper endless track and converted into a force pushing the mould blocks and carriers up the inclined run. The power transmission means may take various forms but in the preferred embodiment it includes a first rotatable gear and a second rotatable gear which are in mesh with a rack on the carriers in the vertical run and the inclined run, respectively, of the upper endless track, sprockets mounted to rotate with the first and second rotatable gears, respectively, and an endless chain connecting the two sprockets and constraining them to rotate in unison. Further features and advantages of the present invention will be apparent from the following description of one preferred embodiment thereof which is given with reference to Figures 7 and 8 of the accompanying drawings, in which: Figure 7 is a diagrammatic side view of an endless track type continuous casting machine in accordance with the present invention; and Figure 8 is a sectional view on the line VIII-VIII in Figure 7. The same reference numerals are used to designate similar components throughout the Figures. A gear 26 supported by bearings 25, as shown in Figure 8, cooperates with the lower portion of the vertically downward run of the upper mould assembly 2 adjacent to the upstream end of the mould cavity 3 and is in mesh with each rack 15. A sprocket 27 is carried by the shaft of the gear 26. Cooperating with the inclined portion of the upper mould assembly adjacent the downstream end of the mould cavity 3 and on each side thereof are a sprocket 28 and a gear 29 carried by a single shaft. The gears 29 are in mesh with a respective rack 15 and the two pairs of sprockets 27 and 28 are coupled by means of a respective endless chain 30. Continuous casting with the casting machine described above is carried out in a manner similar to that described with reference to Figures 2 to 6. When the upper mould assembly 2 passes along the vertical downward path 11 adjacent to the upstream end of the mould cavity 3, the gears 26 are driven though the racks 15 by the downward force of the mould blocks above it. The rotation of the gears 26 is transmitted through the sprockets 27, the endless chains 30, the sprockets 28, the gears 29 and the racks 15 to the mould blocks 1 moving along the inclined path 9 adjacent to the downstream end of the mould cavity 3 and serves to push the mould blocks 1 and their carriers 14 of the upper mould assembly 2 up the inclined path. As a result, the horizontal run of the upper mould assembly 2 which defines the upper casting surface of the mould cavity 3 is prevented from becoming slack. Furthermore, execessive forces are not exerted at the interfaces between the adjacent mould blocks 1 of the upper mould assembly which define the mould cavity 3 so that these interfaces are not damaged. Moreover, the moment applied to each carrier 14 is reduced so that the desired degree of flatness of the mould blocks and their carriers can be maintained. As a consequence, the predetermined cross-sectional configuration of the mould cavity 3 can be maintained with a high degree of dimensional accuracy so that a high-quality casting is obtained.

Claims: 1. A continuous casting machine of endless track type including a plurality of mould blocks and associated carriers connected to form two endless tracks arranged one above the other, the endless tracks having respective substantially horizontal runs which cooperate to define a mould cavity and, in use, are moved in the same direction, each endless track having a run which extends substantially vertically from the upstream end of the mould cavity and a further run which is inclined to the horizontal and extends in the direction of movement of the said horizontal runs from the downstream end of the mould cavity characterised by power transmission means (15, 26, 27, 28, 29, 30) in engagement with the carriers (14) of the mould blocks (1) in the vertical run (11) and the inclined run (9) of the upper endless track (2) and arranged to convert a proportion of the downward force due to the weight of the mould blocks (1) and carriers (14) in the vertical run (11) into a force pushing the mould blocks (1) and carriers (14) up the inclined run (9). 2. A machine as claimed in claim 1 characterised in that the power transmission means includes a first rotatable gear (26) and a second rotatable gear (29) which are in mesh with a rack on the carriers (14) in the vertical run (11) and the inclined run (9), respectively, of the upper endless track (2), sprockets (27 and 28) mounted to rotate with the first and second rotatable gears (26 and 29), respectively, and an endless chain (30) connecting the two sprockets (27 and 28) and constraining them to rotate in unison.

Inventors: HASEBE, NOBUHISA, OSADA, SHIRO, 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