1. Field of the Invention
This invention relates to a sliding nozzle apparatus which is used for controlling the flow of the molten metal poured from a molten metal holding vessel.
2. Description of the Prior Art
There are known various types of sliding nozzle apparatuses which are used for the purpose hereinabove stated. One of them is shown by way of example in FIGS. 4 and 5.
The apparatus is associated with a vessel 1 for holding molten steel. The apparatus includes an upper nozzle member 3 provided in the bottom wall of the vessel 1 which is formed by a steel plate shell 2 and a refractory wall lining it. An upper bracket 5 is secured to the shell 2 and supports a fixed plate 4 having an axial hole aligned with the nozzle member 3.
The apparatus also includes a sliding plate 6 which is horizontally slidable relative to the fixed plate 4, and a lower nozzle member 7. The sliding plate 6 and the lower nozzle member 7 are supported in a slidable supporting member 8 which is supported in a lower bracket 11 horizontally slidably by a drive cylinder. The lower bracket 11 has one edge connected rotatably to the upper bracket 5 by pins 14. Another edge of the lower bracket 11 which is remote from its rotatably connected edge is removably connectable to the upper bracket 5 by a bolt 15 and a nut 16 as shown in FIG. 5, so that the lower plate 6 and the lower nozzle member 7 may be aligned with the upper plate 4 and the upper nozzle member 3. The lower bracket 11 is provided with a coil spring 10 adjacent to each of the edges at which it is, or can be, connected to the upper bracket 5. Each spring 10 is preloaded by a bolt 12 and a nut 13. A holder 9 for holding the heads of the bolts 12 is disposed between the slidable supporting member 8 and the lower bracket 11.
When the apparatus is moved from its position shown in FIG. 4 to its position shown in FIG. 5, the lower bracket 11 is rotated toward the vessel 1 and connected to the upper bracket 5 by the bolt 15 and the nut 16, whereby the slidable plate 6 is pressed against the fixed plate 4.
Until the nut 16 is appropriately tightened, however, the two plates 4 and 6 contact each other only at the edges thereof which are closed to the hinged joint between the upper and lower brackets 5 and 11, while a clearance exists between the plates 4 and 6 at the opposite edges thereof as shown at .delta. in FIG. 5. The force created when the nut 16 is tightened is, therefore, concentrated on the mutually contacting portions of the plates 4 and 6 and thereby causes their surfaces to crack or get otherwise damaged.