Abstract:
A circular, surface-coating application of sprayable composition or mortar is achieved through a rotatable spray head with at least one lateral discharge opening. The composition or mortar is distributed as uniformly and over as large a surface area as possible in the vicinity of the spray head. The spray head is moved axially forwards and back in an axial direction through the same distance during conveying of the composition or mortar and is rotated automatically through the same angular distance about the axis.

Description:
BACKGROUND OF THE INVENTION 
     The present invention relates to a method and an apparatus for the circular, surface-coating application of sprayable compositions or mortars from a rotatable spray head with at least one lateral discharge opening, which is connected to a supply line for the composition or the mortar and optionally for a conveying medium, particularly for repairing a nozzle brick of a metallurgical vessel. 
     Bricks, for instance a nozzle brick, of a metallurgical vessel wear away. They are repaired before being replaced by spraying compositions or mortar onto the worn regions. Apparatus for spraying a repair composition onto a nozzle brick is described in DE 38 33 506 C2. A spray head for applying the repair composition is pushed through the nozzle brick so that composition is applied by the spray head to the worn region in the interior of the vessel. The spray head is axially movable and rotatable about its axis. It is left open as to how the axial displacement and the rotation of the spray head is to be achieved. Since the worn region cannot be seen, a suitable distribution of the repair composition is difficult. 
     SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a method and apparatus of the type referred to above in which the composition or the mortar is automatically distributed as uniformly as possible in the vicinity of the spray head. 
     In accordance with the present invention the above object is achieved in the method of the type referred to above by moving the spray head axially through the same distance forwards and back (a working step) while the composition or the mortar is conveyed in the axial direction and by rotating the spray head about its axis during each working step by the same angular distance (a rotational step). The spray head is moved axially forwards and back in each working step so that the composition is distributed radially over a region which is substantially larger radially than without axial movement. Furthermore, the spray head is necessarily rotated through a predetermined angular distance in each working step, whereby the spray head is rotated through 360° after a plurality of working steps. The composition is thus also uniformly distributed over the peripheral region. Taken together, the composition is thus distributed over a comparatively large circular area on the component, particularly nozzle brick, to be repaired. The working steps can be performed manually or mechanically, for instance pneumatically or electrically. The rotational steps result from positive coupling with axial or lifting movement. 
     An apparatus for carrying out the method provides that a supply line is fixedly connected to the spray head and is mounted so as to be axially movable and rotatable about an axis in a cylindrical guide housing which is fixable in position with respect to the component to be coated with composition or mortar, and that a drive moves the supply line incrementally axially and in rotation. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Further advantageous embodiments of the invention will be apparent from the dependent claims and the following description of an exemplary embodiment. In the drawings: 
     FIG. 1 is a partial sectional view of an apparatus for applying a composition according to the invention, the apparatus being shown inserted into a nozzle brick; 
     FIG. 2 is a sectional view taken on line II--II in FIG. 1; 
     FIG. 3 is a partial sectional view of the apparatus during an advancing movement; 
     FIG. 4 is a partial sectional view of the apparatus after a first rotational movement; 
     FIG. 5 is a schematic view corresponding to FIG. 4; 
     FIG. 6 is a schematic view of the apparatus during a second rotational movement; and 
     FIG. 7 is a sectional view of a spray head of the apparatus taken on line VII--VII in FIG. 1. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The apparatus of the invention includes a cylindrical guide housing 1 securable by means of a flange 2 thereof to the exterior of a metallurgical vessel so that housing 1 is fixed opposite to a nozzle brick L. The cylindrical guide housing 1 extends in the installed state into a passage or hole M of the nozzle brick L (see FIG. 1). If the hole M is conical, the cylindrical guide housing 1 can be provided with a correspondingly conical shell which ensures as close as possible of an engagement of the cylindrical guide housing 1 in the hole M. A worn side S of the nozzle brick L, which is to be coated with composition or mortar, is situated within the metallurgical vessel. 
     Connected to the internal periphery of the cylindrical guide housing 1 are a plurality of guide bars 3 which extend parallel to axis A of housing 1. Between the guide bars 3 are guide grooves 4 extending parallel to axis A. Each guide bar 3 is provided at its upper end with a bevel or beveled end 5. The upper ends of the guide bars 3 terminate before an upper closure 6 of the cylindrical guide housing 1. Eight guide bars 3 are uniformly distributed or spaced around the inner periphery of the cylindrical guide housing 1 (see FIG. 2). It is also possible to provide an even number of guide bars 3 greater than eight. 
     A supply line is guided to be axially movable along axis A and rotatable about axis A within the cylindrical guide housing 1. Rigidly secured to the supply line outside the cylindrical guide housing 1 is a spray head 7 having at least one spray nozzle 8 directed onto the side S of the nozzle brick L. The supply line comprises an outer tube 9 and an inner tube 10 coaxial therewith. The composition may be supplied to the spray head 7 through the inner pipe 10. A conveying medium, for instance compressed air, which improves the spraying of the composition, may be supplied to the spray head 7 through a space 11 between the outer tube 9 and the inner tube 10. 
     Rigidly secured to the outer tube 9 is a rotary head 12 which has radial dogs 13 which are provided for engagement in the guide grooves 4. The rotary head 12 has four dogs 13 in the exemplary case. Formed on an axial engagement surface of the rotary head 12, particularly on dogs 13, are teeth 14 each having a longer flank 15 and a shorter flank 16. The teeth 14 define a rear or outer end surface of the rotary head 12. 
     Mounted on the outer pipe 9 so as to be axially movable and not rotationally fixed is a crown plunger 17 having projections or noses 18 which engage in the guide grooves 4. The crown plunger 17 is thus rotationally fixable and axially movable with respect to the cylindrical guide housing 1. On a front or inner end surface, which is directed towards the rear end surface of the rotary head 12, that is to say teeth 14, the crown plunger 17 has eight teeth 19 which are uniformly distributed around its periphery. Only four of teeth 19 are seen in FIG. 2 because the teeth 19 therebetween are concealed by the dogs 13 or the teeth 14 on the rotary head 12. 
     Arranged outside the cylindrical guide housing 1, between an outer or rear end surface 20 of the crown plunger 17 and an abutment ring 21 secured to the outer pipe 9, is a compression spring 22. A lifting mechanism 23, which together with the device described above constitutes a lifting and rotary drive for the spray head 7, engages the crown plunger 17 outside the cylindrical guide housing 1. The lifting mechanism 23 may be actuated manually or pneumatically or electromechanically. 
     The mode of operation of the above apparatus is as follows. The lifting mechanism 23 is actuated while composition or mortar is conveyed through the inner pipe 10 and compressed air is conveyed through the space 11. If the lifting mechanism 23 is moved in one direction, starting from the position illustrated in FIG. 1, then the crown plunger 17 moves in the direction of an advancing stroke V. Crown plunger 17 pushes with half of its teeth 19 against the tooth flanks 15 of the teeth 14 of the dogs 13 on the rotary head 12. The teeth 19 and the tooth flanks 15 initially can not yet slide against one another because, not only is the crown plunger 17 guided so as to be non-rotatable but axially movable by its noses 18, but dogs 13 of rotary head 12 also are guided in guide grooves 4 so as to be non-rotatable and axially movable (see FIG. 3). The spray head 7 thus is moved upwardly, i.e. inwardly. 
     Towards the end of the advancing stroke V, the dogs 13 move out of the guide grooves 4 because they move beyond the guide bars 3 (see FIG. 4). Under the action of the prestressed compression spring 22, the flanks 16 of the teeth 14 of the rotary head 12 now move onto the root of the teeth 19 on the crown plunger 17 (see FIG. 4), whereby the rotary head 12 rotates slightly in a first rotational movement until the dogs 13 no longer can come between the same guide bars 3 during further movement. The compression spring 22 partially relaxes, but however still remains stressed. The outer pipe 9 and the inner pipe 10 and the spray head 7 also rotate corresponding to the rotation of the rotary head 12. 
     FIG. 5 shows the described steps schematically to make them clear. The flank 15 of a tooth 14 on a dog 13 engages a tooth 19 on the crown plunger 17. Since the dog 13 is free from the guide bars 3, its tooth 14 can slip under the action of the compression spring 22 onto the root between the adjacent teeth 19 on the crown plunger 17. This is indicated by arrow a in FIG. 5. The aforementioned first rotational movement thus occurs. The tip of the tooth 14 is then positioned above the bevel 5 of the next guide bar 3. The tooth 14 thus can no longer slip into that groove 4 from which the dog 13 was moved during the advancing stroke V. 
     The lifting mechanism 23 is then subsequently moved in the other direction (return stroke R). The flanks 15 of the teeth 14 on the rotary head 12 then move onto the bevels 5 on the guide bars 3 (see FIG. 6) and move into the respective adjacent guide groove 4, which is indicated by the arrow b in FIG. 6. A second rotational movement thus occurs which is in the same direction as the first rotational movement. The first rotational movement and the second rotational movement together constitute a rotational step which is 45° in the exemplary case. The spray head 7 thus has rotated further through 45° and then moves in the course of the return stroke R of the crown plunger 17 back into its axial starting position. In each working step (advancing stroke with return stroke) the spray head 7 thus rotates through the same rotational step, 45° in the exemplary case. The side S thus is covered circularly uniformly with the composition discharging from the spray nozzle 8. During the return stroke R the compression spring 22 recovers its full prestressing. The spring stroke is dependent on the tooth height and the bevels on the guide bars 3. 
     The spray head 7 has a second spray nozzle 8&#39; in FIG. 7. This is so offset on the periphery of the spray head 7 that it is situated between the rotary step positions, 45° in the exemplary case, of the spray nozzle 8. The spray nozzle 8 thus is offset with respect to the spray nozzle 8&#39; by one or more times 45° plus 22.5°, an offset of 112.5° being selected in the exemplary case (see FIG. 7). The result of this is that the spray nozzle 8&#39; covers peripheral regions which are not covered directly by the spray nozzle 8 during its rotational steps. This improves the uniform distribution of the composition. 
     In order to achieve a yet more thorough distribution of the composition, even when using only one spray nozzle 8, the rotational steps may be made smaller. For this purpose, correspondingly more guide bars 3 and teeth 14 are then provided on the rotary head 12. The number of the teeth 14 corresponds in each case to half the number of guide bars 3.