Abstract:
Arrangement for the maintenance of a sliding closure mounted on the spout of a container for molten metal. The arrangement includes at least one tool magazine, at least one replacement part magazine and a system for opening and closing the sliding closure. The robot includes an automatic grip changing system and is operationally connected to a control unit to enable it to automatically detect the exact position of the container or of the sliding closure. Thereafter, the robot can control opening and closing of the sliding closure and, depending on the condition of the individual components to be replaced, it can grip tools or replacement parts from the magazines surrounding the robot and can perform cleaning operations, dismantle components and replace or reinstall the same. In this way, personnel can be saved and the occupational safety is thus increased.

Description:
FIELD OF THE INVENTION 
     The invention relates to an arrangement for the maintenance of a sliding closure mounted on the spout of a container for molten metal with at least one tool magazine, at least one replacement part magazine, and a robot provided with an automatic grip changing system that is at least operationally connected to a control unit. 
     BACKGROUND OF THE INVENTION 
     Sliding closures on the spout of containers for molten metal are known in many different embodiments, these basically possibly being sliding closures with a linearly adjustable slider unit (see e.g. EP-A-0 875 320) or rotary sliding closures (see e.g. CH-A-649 149). As is well known, the fire-resistant components of these sliding closures, in particular the closure plates, but also their spout covers and the covers on the container outlet, are subjected to heavy wear and tear and must from time to time be inspected and if need be be changed. The emptied container, e.g. a so-called pan, is brought together with the sliding closure to a maintenance point, a so-called pan position, where the horizontally positioned pan is cleaned, the sliding closure is opened, and the individual components which if need be are to be replaced, are dismantled using appropriate tools, cleaning operations are performed and then the components or the replacement parts for the latter are assembled again. In the specialist jargon this maintenance is also called preparation. These maintenance and preparation operations must be carried out manually. The way in which the sliding closure is opened and the means for opening and closing the sliding closure depend upon the design of the respective closure. 
     A sliding closure provided with a linearly adjustable slider unit is—as described for example in EP-A-0 875 320—actuated by means of a piston/cylinder unit that can be mounted on the sliding closure in order to open or close the pouring channel. Unlike the sliding closure, the piston/cylinder unit is not always attached to the pan, but it remains—once again removed from the sliding closure—on the pouring unit or in the pan position where the opening and closure of the pouring channel is to take place. When mounting on the sliding closure, the cylinder is inserted into a retainer on the slider housing and held securely in position in the latter while the drive rod is coupled to the slider unit. The slider unit&#39;s stroke for opening and closing the pouring channel is restricted by a stroke limitation bolt. If the closure plates are to be changed, the stroke limitation bolt is removed and the slider unit pushed out over the one limit position after which it is released from the slider housing and pivoted out in relation to the latter, and the closure plates are made accessible. 
     With a changing device according to publication JP-A-10263796 for changing a fire-resistant material in a sliding closure mounted on a steel pan, a stage moveable on rails and a robot disposed on the latter are provided which can be equipped with various tools. Moreover, slider plates and cover magazines are provided in addition to the robot on this stage. 
     The object which forms the basis of the present invention is to provide an arrangement of the type specified at the start with which the maintenance and preparation operations can be substantially facilitated. 
     This object is achieved according to the invention by an arrangement wherein a robot is able to automatically detect an exact position of a container or of a sliding closure, means for opening and closing the sliding closure are provided which comprise a piston/cylinder unit which can be brought by the robot from a repository to the sliding closure and that are mountable on the sliding closure and connectable to a pressure source, and wherein the robot can, depending on the condition of individual components that might need to be replaced, grip tools or replacement parts from the magazines surrounding it and perform cleaning operations, dismantle components and replace or reinstall the same. 
     Further preferred embodiments of the arrangement according to the invention form the subject matter of the dependent claims. 
     Advantages are obtained with this arrangement according to the invention—on the one hand that fewer staff members are needed to carry out the maintenance and preparation operations, which reduces costs, it also being guaranteed that the operations proceed without any error. Moreover, there is a higher level of work safety then with the conventional preparations because the operators no longer need to carry out work directly in front of the hot pan. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the following the invention is described in greater detail by means of the drawings. These show as follows: 
         FIG. 1  an arrangement according to the invention for the maintenance of a sliding closure; 
         FIG. 2  a longitudinal view of an exemplary embodiment of a sliding closure on the spout of a partially illustrated container for molten metal; and 
         FIG. 3  an arrangement according to the invention with a pan position comprising a number of pans. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       FIG. 2  shows a portion of a container  10  for molten metal, a so-called pan, on the spout of which a sliding closure  20  is mounted. The container  10  has an outer steel jacket  11 , a fire-resistant coating  12  embedded into the latter, and an outlet  14  which is formed from a fire-resistant perforated brick  15  and a fire-resistant cover  16  inserted into the latter. 
     The sliding closure  20  can for example be the sliding closure known from EP-A-0 875 320 and also described in detail in EP-B-0 277 146. The latter comprises an upper housing part  21  with a fire-resistant closure plate  23  inserted therein and a housing frame  22  with a slider unit  25  releaseably braced therein in which a fire-resistant slider plate  24  is inserted to which a fire-resistant spout cover  28  is attached. By moving the slider unit  25  the outlet  14  and a pouring channel  14   a  can be brought from the opening position illustrated in  FIG. 2  into a throttle or closed position (and vice versa). 
     The linear adjustment of the slider unit  25  is implemented by means of a piston/cylinder unit  30  which is removeably disposed in a retainer  28  flanged onto the upper housing part  21 , i.e. contrary to the sliding closure  20  the piston/cylinder unit  30  does not remain constantly on the container  10 , but is left on the pouring stage or also on the maintenance point, the so-called pan position. The cylinder part of the piston/cylinder unit  30  is pushed into the retainer  28 , a drive rod  32  of the same is then coupled to a driving rod  27  of the slider unit  25  by means of a coupling  19 . 
     The stroke of the slider unit  25  for the adjustment from the opening position shown into the closure position is restricted by a stroke limitation bolt  56  which is inserted removeably into the retainer  28  and passes through a longitudinal opening in the driving rod  27 . The stroke limitation bolt  56  can be disengaged from the longitudinal opening if, for example, a closure plate change is to take place. The slider unit  25  can then be moved beyond the closure position over corresponding guide tracks and be released from the frame  22  and from the upper housing part  21  and be pivoted out in relation to the latter. 
     With the embodiment shown in  FIG. 2  the slider unit  25  is pivoted out downwardly about a horizontal axis A, but pivoting out to the side could also be provided. In the pan position already mentioned, where maintenance of the container  10  and of the sliding closure  20  takes place, the container or the pan  10  are brought into a horizontal position and the direction of movement of the slider unit  25  extends vertically so that in the embodiment according to  FIG. 1  the slider unit  25  can be pivoted horizontally, and this is associated with little expenditure of energy. 
     In the pan position the fire-resistant closure plates  23 ,  24  subjected to a high degree of wear and tear, the fire-resistant spout cover and the fire-resistant cover  16  for the container outlet  14  in particular are respectively inspected and if need be replaced. Various other parts such as ceramic rings, breakthrough safety devices, fire-resistant flushing cones etc. are also replaced however. Until now it was normal to carry out the component disassembly, the maintenance operations and the re-assembly or replacement of components manually. 
     According to the invention, according to  FIG. 1  an arrangement for the maintenance of the container spout and the sliding closure  20  mounted on the spout of the container  10  is provided for the pan position, an exemplary embodiment of which is indicated in  FIG. 2 . The arrangement comprises a robot  60  provided with an automatic grip changing system  61  which is disposed in a robot cell  62  defined by protective enclosures  63 , surrounded by at least one tool magazine  65 ,  66 , at least one replacement parts magazine  67 , various repositories and/or intermediate repositories  69 ,  70 , waste containers  71 ,  72  etc, connection points for current, compressed air, oxygen, hydraulic oil etc. also being provided. The robot is operationally connected to a control unit  75  which, together with an operator panel  89 , is fitted in a separate switch cabinet outside of the robot cell  62 . 
     The robot cell  62  can be entered via a door  76  which can be locked before and during use of the robot. Replacement parts are subsequently supplied via a further door  77 . 
     The robot  60  essentially comprises a base  60   a , a lateral arm  60   b  on the latter rotatable about a vertical axis with a piston/cylinder unit  60   d  and a pivot bearing  60   c , a longitudinal arm  60   e  mounted pivotably on the latter, a further additional arm  60   f  which is held rotatably on the end of the longitudinal arm  60   e , a bracket  60   g  held flexibly on the additional arm  60   f , and the grip changing system  61  pivotable within the latter. The piston/cylinder unit  60   d  disposed to the side of the lateral arm  60   b  is used to adjust the longitudinal arm  60   e . Otherwise the robot  60  has further motors and position measuring implements which are not shown in detail. 
     By means of its construction the robot  60  is able to automatically detect the exact position of the container  10  or of the sliding closure  20 , for which purpose a camera can be coupled to the automatic grip changing system  61 . If a pan  10  is lying in the pan position, the operator starts the cycle. The robot  60  connects the camera which identifies the pan position and the pan number and by means of which a signal is emitted in order to open the heat shield  79 . The camera is then positioned a small distance in front of the slide, and the exact slide position is identified and established. After the position has been identified, the camera is put back in the corresponding tool magazine by the robot  60 . 
     The robot cell  62  is equipped with means for opening and closing the sliding closure  20 , for example with the piston/cylinder unit  30  already mentioned, which is placed in a repository  70  in the form of a retainer. The robot  60  can remove the piston/cylinder unit  30  from the repository  70  with a gripper, insert it into the retainer  28 , and couple it to the slider unit  25 . By means of the robot  60  the connection to a pressure source to the piston/cylinder unit  30  is also provided; corresponding hydraulic hoses are suspended on a gallows  80  above the robot cell  62 . By means of the robot  60  the stroke limitation bolt  56  is also engaged with or disengaged from the driving rod  27 . 
     Before the sliding closure  20  is opened, a measuring coil for establishing waste fitted in the region of the container outlet  14  is preferably examined. The robot  60  docks a tool plate with an implement for testing the measuring coil and couples it to a connector on the pan side. The control unit  75  provides the evaluation implement with a start signal, the line and resistance tests are carried out, and the result sent back from the evaluation implement to the control unit is visualised on the operator panel  89 . With a negative result the measuring coil must be changed in the workshop. 
     After a signal for opening the sliding closure has been emitted by the control unit  75  and the pouring channel  14   a  has been opened, cleaning of the pouring channel  14   a  is implemented with the robot  60 . As tools oxygen lances are used by means of which the pouring channel  14   a  can be burnt off. The robot  60  drives the lance deeper and deeper into the pouring channel  14   a . If the robot is driven in fully with the lance, it draws the latter back out of the channel. Before the robot  60  places the respective oxygen lance back in the tool magazine  66  provided for the latter, the length of the lance is tested on a light barrier. If the lance is shorter than the length of the pouring channel, the robot will discard the latter over a waste container and burns off the pouring channel  14   a  again with a new lance. 
     In order to examine the condition of the fire-resistant components which, if need be, are to be replaced, the robot  60  is brought into a home position and the access door  76  is unlocked, whereupon the operator can enter the robot cell  62  and implement the inspection in a way known in its own right. The state of the pouring channel, of the spout cover  26  and of the slider plate  24  is checked. In order to check the state of the container outlet cover  16 , the closure plates  24 ,  23  must be dismantled or it is changed automatically after a specific number of pass-throughs. 
     After this check the operator leaves the robot cell  62 , locks the access door  76 , and enters the scenario to be implemented on the operator panel  89 , after which the robot is started by pressing a key. The following scenarios can be selected here: 
     Scenario 1: no further action 
     Scenario 2: change of the spout cover  26  (working steps: removal of the old spout cover  26 , fitting of a new spout cover  26 ) 
     Scenario 3: change of the spout cover  26  and of the closure plates  23 ,  24  (working steps: removal of the old spout cover  26 , removal of the old closure plates  23 ,  24 , fitting of new closure plates  23 ,  24 ; fitting of a new spout cover  26 ) 
     Scenario 4: change of the spout cover  26 , of the closure plates  23 ,  24  and of the container outlet cover  16  (working steps: removal of the old spout cover  26 , removal of the old closure plates  23 ,  24 , pulling out of the container outlet cover  16 , insertion of a new container outlet cover  16 , fitting of new closure plates  23 ,  24 ; fitting of a new spout cover  26 ) 
     After each of these scenarios the sliding closure  20  is closed and the piston/cylinder unit  30  disassembled. 
     In addition to each of these scenarios, by means of the robot  60  a change of a flushing cone known in its own right and not apparent in the drawing, and which is fitted directly next to the outlet  14  in the container  10  and is used for handling the molten metal, can be implemented. 
     Mortar must be applied to some replacement parts such as the spout cover  26 , the securely fixed closure plate  23 , the container outlet cover  16 , the flushing cone, ceramic rings, breakthrough safety devices or similar before fitting. For this purpose a mortar station  85  is provided on the arrangement according to the invention. The robot  60  passes through beneath a mortar spray device with these replacement parts, the replacement parts provided with mortar then being deposited in an intermediate repository until fitted. For these operations one can also use the time in which there is no pan in the pan position. 
     The tools available in the tool magazine  65  are advantageously respectively equipped with an adapter  86 , and this simplifies gripping of the latter by the robot  60 . 
     When changing the spout cover  26 , a carrying ring of the latter is released by turning using an appropriate tool, the spout cover  26  is placed on a spike, tipped out over the waste container  71 , and the tool set down with the carrying ring. 
     When dismantling the closure plates  23 ,  24 , the stroke limitation bolt  56  is removed and set down using an appropriate tool, and the slider unit  25  is released in the way already described above and pivoted out about the axis A (the hinge parts provided can be seen well in  FIG. 2 ). The closure plates  23 ,  24  are gripped one after the other with a three-jaw gripper in the pouring channel hole, removed and disposed of in one of the waste containers  71 ,  72 . 
     For the dismantling of the cover  16  in the container outlet  14  the robot  60  connects a hydraulically operated tool, passes with its jaws through the pouring channel  14   a , forces the latter apart and draws the cover  16  out of the perforated brick  15  and disposes of the cover  16  in the waste container. If necessary, the cover  16  must be removed using a mallet. The perforated brick  15  is cleaned using a wire brush, a mallet or a cutter, and then blown off with compressed air. 
     Before fitting a new cover  16  in the container outlet  14  a graphite mass is inserted into the perforated brick  15  by means of the robot  60 . After this a new cover  16  provided with mortar is fitted. The robot waits for a curing time of approx. 1 min. The mortar is removed from the bearing surface for the securely fixed closure plate  23  using compressed air. 
     For the fitting of new closure plates  23 ,  24  the head of the cover  16  is cleaned with a rotating wire brush and then with compressed air if no cover change has previously been implemented. The robot  60  grips a new slider plate  24  from the replacement part magazine  67  and places it in the open slider unit. Then a securely fixed closure plate  23  provided with mortar is inserted. 
     The pouring channel is cleaned using compressed air. After removing a blocking piece, the sliding closure  20  is closed and the slider unit  25  is brought into the pouring position after which the stroke limitation bolt  56  is fitted. 
     For the fitting of a new spout cover  26  the robot  60  first of all cleans a corresponding support on the slider plate  24  provided the latter has not previously been changed. The graphite mass is then sprayed onto the support. A new spout cover  26  provided with mortar and the carrying ring are then inserted, and the carrying ring pulled on. The pouring channel  14   a  is cleaned of mortar with compressed air. 
     After closing the sliding closure  20  and the pouring channel  14   a  and uncoupling and setting down the piston/cylinder unit  30 , the heat shield  79  is closed. 
     According to  FIG. 3  an arrangement  50  according to the invention is provided with a pan position which, for example, can accommodate four pans  10  spaced apart equally for maintenance. These pans  10  are generally of the same dimensions. Preferably, for these 4 pans two robots are provided which are of the same design as that of  FIG. 1 . Therefore, these are not described in full detail. Once again these robots  60 , with the magazines  65 ,  66 ,  67  assigned to them, are respectively disposed within a robot cell  62  defined by protective enclosures  63 . 
     Furthermore, this arrangement is characterised in that a mobile cover removal device  40  is disposed on the side of the pan  10  lying opposite the robot  60 . This cover removal device  40  is held onto a carriage  45  by a rod  43 , the carriage  45  being guided adjustably on rails  41 ,  42  extending next to the pans  10 . An arm  46  held on the rod  43  extending into the pan is provided on its head with a corresponding tool (not shown in detail). 
     With this cover removal device  40  the fire-resistant covers  16  forming the spout of the pans  10  and the fire-resistant perforated bricks  15  (see  FIG. 2 ) can be removed by drilling out or similar. However, it is also conceivable with this type of device to improve the pan coating  12  or to remove one or more flushing cones in the pan base. This device  40  can be moved over the rails  41 ,  42  from pan to pan, and so only one is required. 
     This type of arrangement  50  is suitable for continuous casting installations with a number of strands with which more capacity is correspondingly required of the pans. As soon as a pan  10  has been made ready for operation again by the respective robot  60 , this pan can be carried away by a crane and the next pan  10 ′, which lies outside, is brought to the location of the robot.