Abstract:
The invention relates to a method for operating a strip casting machine for producing a metal strip during which molten metal is continuously poured between two casting rolls ( 3, 4 ) that form a casting gap. Sealing plates ( 2   b ) are provided for laterally delimiting the casting gap, whereby the sealing plates ( 2   b ) are displaced during the casting operation in an oscillating manner transversal to the direction of the axis of the casting rolls ( 3 ,) counter to the front surface ( 3   a   , 4   a ) of said casting rolls ( 3, 4 ). Said sealing plates ( 2   b ) are displaced in an oscillating manner in and counter to the direction of the periphery (U 3  and/or U 4 ) of the casting rolls ( 3, 4 ), whereby displacement takes place in an alternating manner along one or the other casting roll edges ( 3   k  and/or  4   k ). Partial solidifcations can, to a large extent, be prevented from forming and can be removed if need be. The produced metal strip has clean edges.

Description:
BACKGROUND OF THE INVENTION 
   The invention concerns a method for operating a strip casting machine for producing a metal strip, and a device for carrying out the method. 
   During casting between two casting rolls forming a casting gap, sealing plates are held against the facing surfaces of the casting rolls to contain and hold the molten metal between the rolls. The fire-proof sealing plates are mainly pressed against the rotating casting rolls. During this, the sealing surfaces are subjected to substantial wear. In the area of the sealing edges, an undesired partial solidification can occur, which in turn may result in damage to the sealing plates along the roll edges. The wash-out, i.e. the wear from the sealing plates within the edge area of the casting rolls will result in poorly cast edges in the metal strip and in the formation of fins in this area. The metal strip with possible fins produced in this way can cause further wear on the sealing plates on the one hand, and can give rise to edge cracks in the metal strip on the other. These defects will necessitate substantial edge trimming and therefore reject losses, which will have a negative effect on the efficiency of the method. 
   Strip casting machines are known where the side seals can be moved or rotated in an oscillating manner in a horizontal or vertical direction in order to avoid uneven wear of the sealing plates, and also to prevent an adhering of the metal strip produced. However, even with these solutions, the risk of a possible partial solidification occurring in the area of the roll edges between the sealing plate and the facing side of the rolls still exists, and partial wear on the one hand as well as strip edge faults on the other may result. 
   SUMMARY OF THE INVENTION 
   It is therefore the task of this invention to provide a method of the type mentioned above, as well as a device for carrying out the method, with which the strip edge quality can be substantially improved and the efficiency of the method increased. 
   This task is solved in accordance with the invention by a method as well as a device of type described below. 
   Preferred embodiments of the method of the invention and the device of the invention form the subject of the dependent subclaims. 
   According to the invention, the sealing plates are moved inwardly and against the direction of periphery of the casting rolls in an oscillating manner during the casting operation, whereby the movement occurs alternately along one or the other casting roll edge. Thus the occurrence of a partial solidification can be mostly prevented and possibly removed, and the metal strip produced in this way will comprise clean strip edges. Strip edge cracks as well as strong signs of wear on the sealing plates will be prevented, which will in turn increase the efficiency of the method (reject losses due to substantial edge cutting is avoided, and longer casting sequences are possible). 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention will now be described in more detail with reference to the drawings, whereby: 
       FIG. 1  shows a perspective illustration of a first embodiment of a device for producing oscillating movements at the side seals of the roll strip casting machine; 
       FIG. 2  shows a cross-sectional view of a part of the roll strip casting machine with the device according to  FIG. 1 ; 
       FIG. 3  shows a side view of a part of the roll strip casting machine with the device of  FIG. 1 ; 
       FIG. 4  shows a schematic view of a side seal; 
       FIG. 5  shows a schematic view of the side seal of  FIG. 4  during the oscillating movement along a first casting roll edge; 
       FIG. 6  shows a schematic view of the side seal of  FIG. 4  during the oscillating movement along a second casting roll edge; 
       FIG. 7  shows a perspective and a cross-sectional view of a lower part of the device of  FIG. 1 ; 
       FIG. 8  shows an overview of the part of  FIG. 7 ; 
       FIG. 9  shows a perspective and a cross-sectional view of an upper part of  FIG. 1 ; 
       FIG. 10  shows an overview of the part of  FIG. 9 ; and 
       FIG. 11  shows a perspective illustration of a second embodiment of a device for producing oscillating movements at the side seals of a roll casting strip machine. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
     FIGS. 1 to 3  show a device  1  for producing oscillating movements at the side seals  2  of a roll strip casting machine which is envisaged for producing a metal strip by continuously pouring molten metal between two casting rolls forming a casting gap. The casting rolls can be seen in  FIG. 2  and have been allocated the reference numbers  3 ,  4 . Two side seals  2  located at both facing sides of the casting rolls  3 , 4  limit the longitudinal expansion of the casting gap and therefore determine the width of the metal strip to be produced. One device  1  each is envisaged for the relevant side seals  2 . 
   The side seals  2  each comprise one fire-proof sealing plate located in a holding frame  2   a  (see  FIG. 3 ), which can be adjusted against the facing surfaces  3   a ,  4   a  of the casting rolls  3 ,  4  by means of an adjustment device  5  that in itself is known and does not need to be described in detail here. The adjustment device  5  is located on a frame  6 . The adjustment device  5  is allocated to a base plate  10  of the device  1 . On the base plate  10  on the one hand, and on the holding frame  2   a  of the side seal  2  on the other, a fork-shaped holder  11 ,  12  each is affixed, the vertically extending shanks of which are connected with each other with a horizontally aligned transverse bolt  13 ,  14 . On the two transverse bolts  13 ,  14 , a substantially vertically orientated piston/cylinder unit is located, the same being slightly tiltable in relation to a vertical plane extending parallel to the base plate  10  and to the side seal  2 , for which the inside surfaces of the shanks can for example take on a slightly convex form at both holders  11 ,  12 . The piston/cylinder unit is connected with a drive in a way not shown in detail here, and has the purpose of creating an oscillating movement of the side seals  2  with its up/down movement. The oscillating movement is not vertical according to the invention, but extends against the direction of periphery U 3 , i.e. U 4  ( FIG. 2 ) of the casting rolls  3 ,  4 , namely alternately along one or the other casting roll edge  3   k , i.e.  4   k  as shown in  FIGS. 5 and 6 . In this way each point of the so-called sealing area  7  of the sealing plate  2   b  is set—as illustrated in FIGS.  4  and  5 —from a neutral position c into an oscillating movement at the circumference of a circle with a center D 3  (axis of rotation of the casting roll  3 ) and with the roll radius a in the direction of periphery U 3 , i.e. in the casting direction, up to the lower dead point d and back against the direction of periphery U 3  up to an upper dead point b.  FIG. 6  shows that each point of the sealing area  7  can also oscillate from a neutral position f on the circumference of a circle with a center D 4  (axis of rotation of the casting roll  4 ) and with the roll radius a in the direction of periphery U 4  between a lower dead point g and an upper dead point e. 
   To convert the oscillating up/down movement created by the piston/cylinder unit into the oscillating movement of the side seals  2  according to the invention as described above the side seals  2  on the one hand, and the locationally fixed base plate  10  on the other, are allocated guide elements, the first part of which is envisaged for steering the side seals  2  along one casting roll edge  3   k , and the second part of which for steering the side seals  2  along the other casting roll edge  4   k . In addition, adjustment means are provided with which the first or the second part of the guide elements can be used alternately. These guide elements as well as the adjustment means will now be described in more detail with reference to  FIGS. 1 to 3  as well as  FIGS. 7 to 10 . 
   On the base plate  10  three position cylinders  20 ,  23 ,  24  (see  FIGS. 1 and 3 ) are located, preferably screwed into the base plate  10 , of which one, the position cylinder  20 , is located in the lower area of the device  1  in such a way that its axis extends in the area of the casting gap, i.e. substantially along a plane that is common to both of the casting roll axis D 3 , D 4 . The two other position cylinders  23 ,  24  are positioned symmetrically in relation to the vertical central axis of the base plate  10 , i.e. the side seals  2  in the upper area of the device  1 , i.e. they are allocated within the expanded area of the side seal  2  and are located at both sides of the fork-shaped holder  11  for the piston/cylinder unit. 
   The lower position cylinder  20  is equipped with a holder  25  for two guide cylinders  33 ,  34  arranged horizontally at a right angle to the position cylinder  20  and facing each other, and the adjustable pistons  33   a ,  34   a  of the holder  25  each serve as support for a guide roll  35 ,  36 . 
   As is also visible from  FIGS. 9 and 10 , the guide rolls  35 ,  36  are bearingly and rotatably positioned on bolts  35   a ,  36   a  which are aligned at right angles to the pistons  33   a ,  34   a  and connected with the same. With the pistons  33   a ,  34   a , the guide rolls  35 ,  36  can be pressed against a lower circular guide  40  fitted, and preferably screwed, to the side seals  2 , i.e. the holding frame  2   a  of the same on both sides. The cross-section of the circular guide  40  comprises rounded outside guide surfaces  41 ,  42  which co-operate with similarly formed circumferential surfaces  35   u ,  36   u  of the guide rolls  35 ,  36 . The lower position cylinder  20  as well as the lower circular guide  40  are located below the lower holder  12  for the piston/cylinder unit  15 . 
   The upper position cylinders  23 ,  24  also each comprise a guide cylinder  43 ,  44  (see especially  FIG. 2 ), the pistons  43   a ,  44   a  of which each serve as a support for a guide roll  45 ,  46 . The guide rolls  45 ,  46  in turn are bearingly and rotatably positioned on bolts  45   a ,  46   a  positioned at right angles to the pistons  43   a ,  44   a  (see  FIGS. 7 and 8 ). On the side seal  2 , i.e. the holding frame  2   a  two upper circular guides  51 ,  52  of the same are affixed (i.e. screwed on in the upper area), which are each equipped with a side guide surface  53 ,  54  facing the outside edge of the side seal  2 . The rounded guide surfaces  53 ,  54  with their outwardly dome-shaped cross-section each co-operate with correspondingly shaped circumferential surfaces  45   u ,  46   u  of the guide rolls  45 ,  46 . 
   The upper circular guides  51 ,  52  are arranged in such a way that their guide surfaces  53 ,  54  each lie along the circumference of the circle with the radius a and the center D 3  (circular guide  51 ), or D 4  (circular guide  52 ) already mentioned above. Around the circumference of the relevant circle, the relevant outside surface  41 ,  42  of the lower circular guide  40  is also located. The upper guide cylinders  43 ,  44  are aligned in such a way that the guide rolls  45 ,  46  are adjusted at a right angle to the relevant guide surfaces  53 ,  54  during the adjustment of its pistons  43   a ,  44   a  to bring them into tangential contact with the same. As already mentioned, the pistons  33   a ,  43   a  and pistons  34   a ,  44   a  are activated alternately according to this invention, and the guide rolls  35 ,  45  are therefore alternately pressed against the guide surfaces  41 ,  53 . Then the guide rolls  36 ,  46  are pressed against the guide surfaces  42 ,  54 , so that the oscillating up/down movement of the piston/cylinder unit  15  alternately oscillates the side seals  2  as shown in  FIG. 5 , and then as shown in  FIG. 6 . 
   Instead of a single lower circular guide  40  with two outside surfaces  41 ,  42 , it is of course also possible to use two separate circular guides with one outside surface each affixed to the holding frame  2   a.    
   Instead of the piston/cylinder unit  15 , it is also possible to use a different conventional drive unit for generating the up and down movements. 
   The oscillating frequency can be varied, whereby the movement of the side seals  2  (i.e. the fire-proof sealing plates  2   b  integrated into the same) in the direction of periphery U 3 , or U 4  of the casting rolls  3 ,  4 , (i.e. the casting direction), can be a little faster, the same, or even substantially slower than the movement of the rotating surface of the casting rolls  3 ,  4 . In other words: a minimal prior advance, an equal advance, or possibly even a substantially lower advance is possible. 
   The movement of the sealing plate  2   b  against the direction of periphery U 3 , or U 4  of the casting rolls  3 ,  4  (i.e. the return movement) can be faster, the same, or even substantially slower than the casting direction movement mentioned above. 
   The oscillating frequency can vary depending on the casting speed. For a simple control, the oscillating frequency can however also be fixed to suit a conventional casting speed. 
   The lift of the sealing plates  2   b  can preferably be +/− 0.5 to +/− 10 mm and occur at a speed that is up to 10% faster during the casting direction movement, and up to 10 times slower during the return movement. 
   The fact that according to the invention, the side seals  2  (i.e. the fire-proof sealing plates  2   b  integrated into the same) are moved in an oscillating way in and against the direction of periphery U 3 , or U 4  of the casting rolls  3 ,  4  during the casting operation, whereby the movement can occur alternately along one or the other casting roll edge  3   k ,  4   k  means that the creation of partial solidifications can be mostly prevented and removed if need be, and that the resulting metal strip can be produced with clean strip edges. Strip edge cracks as well as strong signs of wear on the sealing plates  2   b  can be avoided, so that the efficiency of the method is increased (reject losses due to substantial edge cutting are prevented, and longer casting sequences are possible). 
     FIG. 11  shows a further embodiment of a device  1 ′ for generating oscillating movements on side seals of a roll strip casting machine. It once again comprises a fixed base plate  100 , opposite which a further plate  102  connected with the side seal is moveably located. The side seal itself is not illustrated in  FIG. 11 , but the plate  102  is affixed in the holding frame of the side seal that receives a sealing plate already mentioned above. 
   The moveable plate  102  comprises two side guide surfaces  103 ,  104  along its outside circumference, which each lie on the circumference of a circle with the casting roll radius a and a center D 3 , or D 4  (see  FIG. 4  and  FIG. 5 ) corresponding to the axis of rotation of the relevant casting roll  3 , or  4 . The guide surfaces  103 ,  104  are co-operatively connected with two guide roll pairs  105 ,  106 ,  107 ,  108  symmetrically located in relation to the vertical central plane of the base plate on the fixed base plate  100 , of which one guide roll pair  105 ,  106  is located in a lower, and the other guide roll pair  107 ,  108  in an upper, extended area. 
   In the upper area of the moveable plate  102 , a recess  110  that is symmetrical in relation to the vertical central plane of the same is located, into which two eccenters  111 ,  112  project through the base plate  100  from behind. The eccenters  111 ,  112  can be driven by a drive not shown in the drawing and located outside of the hot section via a drive shaft  113  and a gear wheel  144 ,  115 ;  116 ,  117  in a counter direction. The gear wheel  114  is located on the drive shaft  113 , the gear wheel  115  engaged with the same sits on a shaft allocated to one eccenter  111  and is bearingly positioned in a holder  120 , on which a further gear wheel  116  is also positioned, which engages a gear wheel  117  driven by the other eccenter  112 . 
   The two eccenters  111 ,  112  and the inside surfaces of the recess  110  are matched to each other by means of friction closure in such a way that the moveable plate  102  remains in constant contact with the lower guide rolls  105 ,  106  with its guide surfaces  103 ,  104  during a rotation of the eccenters  111 ,  112 , although the same is pressed alternately against one or the other upper guide roll  107 ,  108 . In this way, the plate  102 , and with it the side seal, carries out a kind of oscillating V movement alternately along one or the other casting roll edge  3   k , or  4   k . The lift of the sealing plates can preferably be from between 0 and 1 mm to between 0 and 20 mm. 
   The side seal with the moveable plate  102  as well as the base plate  100  with the holder  120  and the gear wheels  115 ,  116 ,  117  bearingly positioned in the holder  120  form a unit which is inserted from below following pre-heating in order to fixedly drive the gear wheel  114  located on the drive shaft  113 , whereby the gear wheel  115  is brought into engagement with the fixed gear wheel  114 . 
   In principle, the two upper guide rolls  107 ,  108  of  FIG. 11  can be omitted, and the guiding of the moveable plate  102  can be carried out by the two eccenters  111 ,  112  engaging the recess  110 . The plate  102  would then be held and guided by these eccenters  111 ,  112  on the one hand, and by the two guide rolls  105 ,  106  located at the lower end on the other. 
   In addition, a spring, preferably a pressure spring, can be located between the plate  102  and the base plate  100 , which effects that the moveable plate  102  is always pressed against the eccenters in a downward direction with the inside surfaces of its recess  110 , so that a gap-free positive abutment by means of friction closure of the eccenters is guaranteed.