Clamping and fixing apparatus for a refractory-made plate for a slide gate valve for controlling a molten steel flow
This invention relates to a clamping and fixing apparatus of a refractory-made plate (hereinafter called a plate) for a slide gate valve for controlling a molten steel flow, which apparatus is used when a molten steel is poured out of a vessel for molten steel, such as a ladle or tundish. 
     By the refractory-made plate in the present invention is meant a bottom plate, a slide plate or a seal plate which is used for said slide gate valve for controlling a molten steel flow. 
     As known fixing means there can be mentioned a method (Japanese Utility Model Kokai or Unexamined Utility Model Publication No. 115607/77) of fixing a plate at the flat surface of its shorter edge side, as shown in FIGS. 3 and 4, and a method (Japanese Patent Kokai No. 159260/86) of fixing the plate at its tapered surface, as shown in FIGS. 5 and 6. In these methods the plate is fixed by pressing a plate fixture 2 (or 4, 5 or 6) against the plate by means of a cotter 1 or a bolt 3. However, these methods have the following demerits: 
     (1) In the method of fixing the plate at its flat surface, it is not effective for controlling vertical cracking of the plate but rather it accelerated such cracking thereby shortening the life of the plate. 
     (2) In the method of fixing the plate at its tapered surface, it is effective for controlling the vertical cracking, but according to the known means the plate fixture 5 or 6 is likely to be deformed due to the pressing force of the plate so as to allow the fixture to be spread outwardly. On the other hand, to prevent the deformation it is necessary to make the fixture with considerably a large dimension. 
     Being caused by the deformation of the plate fixture and the irregular dimensions of manufacturing plates, as described above, a surface contact at a tapered surface becomes difficult thereby causing a point or linear contact and concentrating a stress to the plate. This causes crackings to the plate. 
     (3) The bolt 3 shown in FIGS. 4 and 6 sometimes is seized by dust, heat load and the like. In such a case it is not easy to dismantle the bolt, and in the worst case not only the bolt but also a casing 13 may be damaged. 
     Under the circumstances it is earnestly desired to prevent the aforementioned occurrence of cracking to plates and the deformation of a plate fixture and to effect an easy and accurate setting of the plates despite the irregular dimensions of the plates. 
     To solve the various problems given in the aforementioned known means the inventors of this invention have conducted various researches and experiments, and as a result they have succeeded in developing the present invention. Though the technical constitution of the invention is as clearly described in the claims, the invention will now be described more in detail by way of an embodiment with reference to the accompanying drawings. 
    
    
     FIG. 1 is a plan view of the apparatus of this invention, and FIG. 2 is a developed, perspective view of said apparatus. 
     FIGS. 3-6 are plan views of various prior art devices discussed above. 
    
    
     As illustrated, reference numeral 13 designates a casing for housing a slide plate, and guides 16, 16 are projectingly provided at two sides within the longer sides of said casing. A guide piece 11 projects brackets 11b, 11b for engaging with fixtures 12, 12 at the plate 7 side, said brackets anchoring the fixtures 12, 12 rotatably in their plane direction. In the drawings, recessed grooves engaging projections 12a, 12a provided in the fixtures 12, 12 are provided respectively in the brackets 11b, 11b, as illustrated. Said fixtures 12, 12 are provided with plate-contacting surfaces 12b, 12b, and each fixture 12 is constructed in such a manner that it has a sufficient dimension so that part of its peripheral surface may be brought into contact with the inner surface of said casing 13 and the guide piece 11. Additionally, said guide 16 may often be a single one. 
     The guide piece 11 is provided with a dovetail groove recess 11a at the side opposite to the plate 7, and a nut 10 is idly inserted in the recess 11a, said nut being mounted at one end of a bolt 9 which rotates passing through said casing 13, as illustrated. 
     The apparatus of this invention, which is constructed as described above, is assembled and operated as follows. The assembling is made within the casing 13 as shown with one-point broken lines in FIG. 2, and when the bolt 9 is clamped the guide piece 11 and the fixture 12 supported by said guide piece move toward the plate 7 thereby to fix said plate. At this time, each of the fixtures 12, 12 is brought into contact with the casing 13 and the guide piece 11, at a point of its peripheral surface, and it is in contact with the tapered portion of the peripheral surface of the plate, at its contact surface 12b. Since the fixture 12 thus rotates following the different taper angles of different plates 7 the portion of fixing plates 7 makes always a surface contact with the plates, and therefore stress is not concentrated on them. 
     Further, the present apparatus is designed in such a manner that the plate 7 is contact supported at two places of the casing 13 and the guide piece 11 so as to disperse the force generated by the thermal expansion of the plate 7 when in use, i.e. the force caused by the plate pressing. From the strength point of view each portion of the present apparatus can be made compact. Furthermore, in case the screwing portion of said nut 10 and bolt 9 have been sized so as not to move, the nut 10 and the bolt 9 can easily be disengaged from the guide piece 11 by moving the bolt 9 toward the plate 7 to remove it from the casing 13, whereby parts can be replaced very easily. 
     Though the present invention has been described above by way of an example of slide plates it will be evident to those skilled in the art from the above teachings that it is also possible to clamp and fix the plates even in the case of bottom plates or seal plates by means of the same structure as in the present apparatus. 
     In conclusion the clamping and fixing apparatus of this invention has the following merits: 
     (1) Each of the fixtures 12, 12 is mounted to the guide piece 11 rotatably in the plane direction and it necessarily makes a surface contact with the tapered surface of the plate 7, so that stress is not concentrated on the plate. 
     (2) Since the fixture 12 is supported at two places of the casing 13 and the guide piece 11 it is possible to disperse the pressing force of the plate to both the casing 13 and the guide piece 11. Thus the force which acts on the guide piece 11 is reduced so that it becomes to be hardly deformed. 
     (3) Since the nut 10 is mounted disengageably from the guide piece 11, the screwing portion can be easily replaced even when it has been seized.