BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a roller cooling and/or lubricating device for cold rolling mills for strip, in particular, thin strip rolling mills and foil rolling mills, comprising nozzle beams correlated with the individual rollers and mounted on side shields of the roll housings of one or more roll stands, the nozzle beams having spray nozzles mounted therein across the width of the rollers and being adjustable relative to the correlated rollers independent from one another transverse to the running direction of the rolled strip in planes that are parallel to the strip plane, for the purpose of controlling the strip tensile stress across the strip width by a change of the effective roll barrel diameter and/or by affecting the roller lubrication with a pressure-controlled and/or quantity-controlled and/or temperature-controlled supply of rolling oil or emulsions. 
     2. Description of the Related Art 
     The flatness control of the rolled strip in a cold rolling mill for strip, which is furnished with a roller cooling and/or lubricating device of the aforementioned kind known from German patent 34 19 261 C3,is based on a change of the spray pattern of the rolling oil sprayed onto the surface of the working rollers or the sprayed-on emulsions. The change of the spray pattern is effected by an adjustment of the nozzle beam, correlated with each one of the working rollers of the rolling mill, relative to the working roller independent of the respective other nozzle beams transverse to the strip running direction in a plane which is parallel to the strip plane and a pressure-controlled and/or quantity-controlled and/or temperature-controlled supply of rolling oil or emulsions. 
     Thin strip and foil strip, which are rolled on a four-high or six-high roll stand with the known flatness control, are characterized by a high quality with respect to dimensional precision and shape precision as well as flatness. 
     A disadvantage of roller cooling and/or lubricating devices of the aforementioned kind for cold rolling mills of strip is the insufficient accessibility of the nozzle beams with the spray nozzles and their corresponding control valves so that repair and maintenance work on the nozzle beams is cumbersome and time-consuming. 
     SUMMARY OF THE INVENTION 
     It is an object of the present invention to optimize the control of the strip flatness in cold rolling mills for strip by means of the aforementioned roller cooling and/or lubricating device in order to compensate undesirable strip tensile stress deviations within zones in the rolled strip and to improve the accessibility of the spray nozzles, installed in the nozzle beams of the roller cooling and/or lubricating device, and of their corresponding control valves with respect to a simplification and acceleration of required repair and maintenance work. 
     In accordance with the present invention, this is achieved in that: 
     a) the nozzle beams are movable by means of a linear drive (adjusting cylinders) in the direction of their longitudinal axis transverse to the running direction of the rolled strip and rotatable by means of a rotary drive about the longitudinal axis; 
     b) positioning devices are arranged on the roll stand or the roll stands for moving the nozzle beams from a roller-remote maintenance position into the working position at the rollers and from the working position into the maintenance position; 
     c) the control valves of the spray nozzles to be opened or closed are switched in a certain time frame with time delay; 
     d) the spray nozzles, which are mounted at identical spacing within the nozzle beams, have: a nozzle holder, which is inserted into corresponding openings in the front wall section facing a roller as well as the rear wall section of a nozzle beam, sealed relative to the nozzle beam, and penetrates the interior space thereof; moreover, a nozzle head, which is inserted into a bore in the forward end of the nozzle holder facing the roller, preferably is screwed into it, or which is placed onto the forward end of the nozzle holder, preferably screwed thereon, and which has at least one nozzle opening and an ante-chamber; a rotary slide valve which is supported in a central throughbore of the nozzle holder so as to be rotatable about the longitudinal axis of the spray nozzle and has a blind bore open toward the nozzle head and has in the area of the blind bore at least one inlet opening which, in the open position of the spray nozzle, is aligned with a corresponding inlet opening, open toward the interior space of the nozzle beam, of the nozzle holder or the nozzle head, and, in the closed position of the spray nozzle, is closed by a wall of the nozzle holder or the nozzle head; as well as a control member engaging the end of the rotary slide valve remote from the nozzle head. 
     The roller cooling and/or lubricating device has the following advantages. 
     The spray angle of the spray nozzles of the nozzle beams relative to the rollers, which is adjustable by rotating the nozzle beams about the longitudinal beam axis, provides a further parameter in addition to the adjustability of the nozzle beams relative to the respectively correlated roller transverse to the strip running direction as well as to the change of the quantity, the pressure, and the temperature of the rolling oil sprayed onto the rollers or the sprayed-on emulsions for changing the spray pattern on the roller surface within the context of a strip flatness control. The spray angle of the spray nozzles as an additional parameter makes possible an optimization of the strip flatness control. By rotating the nozzle beam by 180°, the spray nozzles can be moved in a simple way from the roller-proximal working position into a roller-remote maintenance position for a simple and fast performance of required maintenance and repair work. The positioning devices mounted on the roll stands make possible a simple movement of the nozzle beams from the working position at the rollers into a maintenance position remote therefrom in which all nozzle beams are easily accessible for repair and maintenance work. By the successive switching of the control valves of the spray nozzles to be opened or closed in a certain time frame with a time delay, the pressure in the cooling medium supply lines of the spray nozzles can be maintained substantially constant independent of the number of actuated nozzles so that liquid shocks as a result of pressure fluctuations, which can result in damage to the cooling medium lines and the control valves, are prevented. The rotary slide valve which is used for the spray nozzles of the roller cooling and/or lubricating device requires together with the control member, that, as a result of the small mass of the rotary slide valve, needs only a minimal control force, only little space so that the mounting space necessary across the strip width for each individual spray nozzle is significantly smaller in comparison to known roller cooling and/or lubricating devices, and the spray zone width of the spray nozzles is correspondingly reduced and, accordingly, the precision of the strip flatness control is significantly improved. 
     The invention will be explained in the following with the aid of schematic drawings of a roller cooling and/or lubricating device used in a four-high stand. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     In the drawing: 
     FIG. 1 is a perspective illustration of a four-high stand with nozzle beams for cooling and lubricating the working rollers and the support rollers; 
     FIG. 2 is a front view of the nozzle beams according to FIG. 1; 
     FIG. 3 is a section illustration of a rotational and sliding support of one end of a nozzle beam positioned in the working position; 
     FIG. 4 is a section view of a rotational and sliding support of the nozzle beam in a maintenance position which is rotated by 180° relative to the illustration of FIG. 3; 
     FIG. 5 is a four-high stand with nozzle beams in the maintenance position, a removal hasp, and devices for introducing the rolling strip into the rolling gap; 
     FIG. 6 shows the four-high stand corresponding to FIG. 5 with nozzle beam in the working position; 
     FIG. 7 shows the control of the spray nozzles for a four-high stand; 
     FIG. 8 is a longitudinal section of a spray nozzle provided with a rotary slide valve in the closed position; 
     FIG. 9 shows in an illustration corresponding to FIG. 8 the spray nozzle in the open position; and 
     FIG. 10 shows an altered embodiment of the spray nozzle according to FIGS. 8 and 9. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The four-high stand of FIG. 1 is comprised of two roll housings, not shown, in which in chocks, not shown, an upper working roller  3  and a lower working roller  2  as well as a lower support roller  4  and an upper support roller  5  are rotatably supported. 
     The roller cooling and/or lubricating device, suitable for the flatness control of the rolled strip  6 , for the working rollers  2 ,  3  and the support rollers  4 ,  5  is comprised of a nozzle beam  7 ,  8 , respectively, for the working rollers  2 ,  3  and a nozzle beam  9 ,  10  for the support rollers  4 ,  5 , respectively. 
     Across the width of the rollers, spray nozzles  11  are mounted in the nozzle beams  7 - 10  with control valves  12 , arranged upstream thereof and formed as solenoid valves, for supplying cooling oil and/or emulsions onto the rollers  2 - 5 . The nozzle beams  9 ,  10  correlated with the support rollers  4 ,  5  are stationary, while the nozzle beams  7 ,  8  correlated with the working rollers  2 ,  3  are slidable in the direction of arrows b, c in the direction of their longitudinal axis  13 — 13  transverse to the strip running direction a across the strip width and rotatable about their longitudinal axis  13 — 13 . 
     The respective supply of rolling oil and/or emulsions to the adjustable nozzle beams  7 ,  8  and the stationary nozzle beams  9 ,  10  is controlled with pressure control and/or quantity control and/or temperature control. 
     By a movement of the nozzle beams  7 ,  8  in the direction of the longitudinal axis  13 — 13  of the beams transverse to the running direction a of the rolled strip  6  and by rotating the nozzle beams  7 ,  8  about the longitudinal axis  13 — 13  of the beam for adjusting the spray angle of the spray nozzles  11  relative to the working rollers  2 ,  3 ,the spray zone width of the spray nozzles  11  onto the working rollers  2 ,  3  and the spray pattern of the spray nozzles  11  are adjusted. The control of pressure, temperature, and quantity of the rolling oil, respectively, of the sprayed-on emulsions supplied to the nozzle beams  7 ,  8  affects the cooling of the working rollers  2 ,  3  and thus the size and the speed of the change of the effective roll barrel diameter and of the rolling gap  14 , dependant thereon, between the working rollers  2 ,  3 , respectively, affects the lubrication of the working rollers. 
     By means of a flatness measuring roll, not illustrated, at the exit of the strip behind the roller set, values of the strip tensile stress distribution across the strip width of the rolled strip  6  are measured, then processed in a computer, and used for controlling the cooling and/or the lubrication of the working rollers  2 ,  3  by means of the movable and rotatable nozzle beams  7 ,  8 . 
     With a precise positioning of the nozzle beams  7 ,  8  with the spray nozzles  11 , which beams are moveable in the direction of the longitudinal beam axis  13 — 13  transverse to the strip running direction a and rotatable about the longitudinal beam axis, undesirable strip tensile stress deviations can be compensated in zones within the rolled strip  6 ,and a planar strip can be produced thereby. 
     On the two ends  15 ,  16  of the two nozzle beams  7 , 8  correlated with the working rollers  2 ,  3 , adaptors  17  are mounted on two hollow bearing journals  18 ,  19  for rotatable and movable support of the nozzle beams about and in the direction of the longitudinal beam axis  13 — 13 . The bearing journals  18 ,  19  are provided in the side shields  20 ,  21  on the two roll housings (not illustrated) of the four-high stand  1  wherein the supply of cooling medium, respectively, of emulsions to the spray nozzles  11  mounted in the nozzle beams  7 ,  8  and to the corresponding control valves  12  is realized by a supply line  22  in a side shield  20 , the hollow space  23  of the bearing journal  18  mounted in the side shield  20 ,the interior space  24  of the adaptor  17  seated on the bearing journal  18 , and the distribution channel  25  of the nozzle beams  7 ,  8 . 
     The supply of cooling medium to the nozzle beams  7 ,  8  can also be realized by a respective supply line  22  in both side shields  20 ,  21 , the hollow bearing journals  18 ,  19  mounted therein, the adaptors  17  seated thereon, and the distribution channel  25  of the nozzle beams. 
     Hydraulic adjusting cylinders  26 ,  27  with adjusting pistons  28 , acting on the adaptors  17 , are arranged on the two bearing journals  18 ,  19  of the nozzle beams  7 ,  8  for moving the nozzle beams  7 ,  8  in the direction of arrows b, c transverse to the running direction a of the rolling strip  6 . 
     A rotary drive  29  is mounted on the side shields  20 ,  21 , respectively, and engages a respective adaptor  17  for rotating the nozzle beams  7 ,  8  about their longitudinal axis  13 — 13   
     The connecting cables for the control valves  12  of the spray nozzles  11  of the nozzle beams  7 ,  8  are combined in several flexible protective hoses  30 , wherein the length of the connecting cables of the control valves is dimensioned such that a rotation of the nozzle beams  7 ,  8  about the longitudinal axis  13 — 13  of the beam is possible. 
     For repair and maintenance work on the spray nozzles  11  the nozzle beams  7 ,  8  can be rotated from their working position according to FIG. 3 by 180° into the maintenance position according to FIG. 4 in which the spray nozzles  11  facing away from the working rollers  2 ,  3  are freely accessible. Maintenance and repair work on the control valves  12  of the nozzle beams  7 ,  8  are expediently performed in the working position of the nozzle beams according to FIG.  3 . 
     In deviation from the afore described embodiment of the roller cooling and/or lubricating device, there is the possibility of providing additionally a movability and rotatability of the nozzle beams  9 ,  10  for the support rollers  4 ,  5  in the direction of the longitudinal beam axis, respectively, about the longitudinal beam axis. 
     In the four-high stand  1  illustrated in FIGS. 5 and 6, the rolling strip  6  is removed from a removal hasp  31  and is guided into the rolling gap  14  via a strip introducing unit  32 , which is comprised of a first air cushion conveyor  33 , a separating blade  34 , a second air cushion conveyor  35 , a rolling unit with two deflecting rollers  36 ,  37 , spaced in the strip running direction a at a spacing from one another, as well as a tension roller  39  arranged therebetween and combined with a third air cushion conveyor  38 . The strip introducing unit  32  is arranged on the machine frame  40  which can be advanced in the strip running direction a and returned counter to the strip running direction in the direction of arrow d. 
     A positioning device  41  is arranged on the four-high stand  1  for moving two nozzle beams  7 ,  8  for the lower and the upper working rollers  2 ,  3  as well as a further nozzle beam  10  for the upper support roller  5  from the roller-remote maintenance position  7   a ,  8   a ,  10   a  into the working position  7   b ,  8   b ,  10   b  at the rollers  2 ,  3 ,  5 . 
     The positioning device  41  is comprised of two lifting beams  43 ,arranged at the inlet side of the strip on the two roll housings  42  of the four-high stand  1  and movable in the vertical direction e, f, as well as two carriages  44  movable thereon in the horizontal direction g, h and having support arms  45  with right-angle bends. The two nozzle beams  7 ,  8  for the two working rollers  2 ,  3  are fastened on the lower ends  46  of the support arms  45 , and the nozzle beam  10  and a stripper  48  for the outer support roller  5  are fastened on the upper portions  47 . 
     Moreover, at the lower ends  46  of the support arms  45  of the carriages  44 , deflecting plates  49 ,  50  for threading the rolling strip  6  into the rolling gap  14  are provided. 
     The nozzle beam  9  for the lower support roller  4  is arranged on the machine frame  40  of the strip introducing unit  32  which is movable in the direction of arrows a, d. 
     In a rolling train with several roll stands  1 , starting at the second roll stand, the nozzle beam  9  for the lower support roller  4  can be mounted behind the removal hasp  31  on the extended lower ends  46  of the support arms  45  of the positioning device  41 . 
     When moving the nozzle beams  7 ,  8 ,  10  from the maintenance position  7   a ,  8   a ,  10   a  illustrated in FIG. 5 into the working  7   b ,  8   b ,  10   b  according to FIG. 6, first the support arms  45  with the nozzle beams  7 ,  8 ,  10  are moved by means of the carriages  44  in the direction of arrow g in front of the strip introducing unit  32 ; subsequently, the nozzle beams  7 ,  8 ,  10  are lowered with the lifting beams  43  in the direction of arrow e to the working level; subsequently, the nozzle beams  7 ,  8 ,  10  are advanced with the carriages  44  into the working position  7   b ,  8   b ,  10   b  at the rollers  2 ,  3 ,  5  by means of the carriages  44 ; and then, the strip introducing unit  32  with the nozzle beam  9  for the lower support roller  4  is advanced in the strip running direction a toward the rollers. 
     The movement of the nozzle beams  7 ,  8 ,  10  and  9  from the working position  7   b ,  8   b ,  10   b ,  9   b  into the maintenance position  7   a ,  8   a ,  10   a ,  9   a  is carried out in the reverse sequence. 
     In the control, illustrated in FIG. 7, of the spray nozzles  11  of the nozzle beams  7 - 10  of a four-high stand  1  correlated with the working rollers  2 ,  3  and the support rollers  4 ,  5 , the control valves  12  of the spray nozzles  11  are pneumatically pilot-controlled by solenoid valves  51 . 
     Instead of the pneumatic pilot-controlled control valves  12  for the spray nozzles  11 , control valves which are embodied as solenoid valves can also be used. 
     The nozzle beams  7 - 10  are connected via distribution lines  52 - 54  as well as a main supply line  55  for the cooling medium with the control valve  56  for pressure and quantity control of the cooling medium to a conveying pump, not shown, of a cooling medium circulation device. 
     When elongate portions occur in the rolled strip, which can be determined by the flatness measuring devices, cooling liquid is sprayed onto the working rollers  2 ,  3  and support rollers  4 ,  5  at these locations by means of the spray nozzles  11 . Accordingly, the effective roll barrel diameter in this area is reduced by cooling. The cooling medium which flows away from the rollers is collected in a collecting tank  57  below the roll stand  1  and is returned into the cooling medium circulation device. 
     Opening or closing of the control valves  12  of the spray nozzles  11 , for example, there may be  40  of them provided, is carried out in a certain sequence within a time frame of, for example, one second, i.e., the individual spray nozzles  11  are switched in time intervals of approximately 26 milliseconds. The switching sequence and the time intervals are controlled by a computer  58 . 
     With such a control, a change of the liquid flows is achieved wherein pressure fluctuations can be prevented by means of a fast pressure control so that the flow-through quantity per control valve remains constant and no damaging liquid shocks can occur. 
     According to FIGS. 8 and 9, the spray nozzles  11 , positioned at identical spacing transverse to the strip running direction a in a cylindrical nozzle beam  59  of a roller cooling and lubricating device, are compact units mounted in the nozzle holders  60  which are inserted into corresponding openings  61 ,  62  in the front wall section  59   a  facing the roller as well as in the rear wall section  59   b  of the nozzle beam  59  from the backside thereof, are sealed relative to the nozzle beam  59 , and penetrate the interior space  63  thereof. 
     The spray nozzles  11  are provided with a nozzle head  64  which is threaded into a threaded bore  65  in the forward end  66  of the nozzle holder  60  facing the roller. The nozzle head  64  has a nozzle opening  67  and an antechamber  68 . 
     Moreover, the spray nozzles  11  are provided with a rotary slide valve  69  which is rotatably supported in a central throughbore  70  of the nozzle holder  60  so as to be rotatable about the longitudinal axis  71 — 71  of the spray nozzles  11 . It is sealed in the bore  70  of the nozzle holder  60  and has a blind bore  72  open toward the nozzle head  64  as well as two diametrically oppositely positioned inlet openings  73  in the area of the blind bore  72 . The inlet openings  73 , in the open position  11 &#39;&#39; of the spray nozzles  11  according to FIG. 9, are aligned with two inlet openings  74  in the nozzle holder  60 , which are open to the interior  63  of the nozzle beam  59 , and, in the closed position  11 &#39; of the spray nozzle  11  illustrated in FIG. 8, are closed by the wall  75  of the nozzle holder  60 . 
     The nozzle holder  60  of the spray nozzle  11  is fastened by means of a flange  76 , formed as a unitary part of the nozzle holder, to the external side of the rear wall section  59   b  of the nozzle beam  59  so as to be rotatable to a limited extent about the longitudinal axis  71 — 71  of the spray nozzle  11 . 
     A control member  77  for actuating the rotary slide valve  69  of the spray nozzle  11  is mounted on the fastening flange  76  of the nozzle holder  60 . The control member  77  may be an electric rotary solenoid, a hydraulic cylinder, or a pneumatic cylinder. Moreover, there is the possibility of employing a step motor for actuating the rotary slide valve  69  and for a simultaneous quantity control of the cooling and lubricating medium. 
     With respect to a spacing of the spray nozzle  11  as small as possible across the width  78  of the rolling strip  6 , the control members  77  for actuating the rotary slide valve  69  of the spray nozzles  11  can be arranged in a staggered arrangement in the direction of the nozzle axes  71 — 71  and/or can be arranged staggered atop one another. 
     Moreover, there is the possibility of providing a rotary adjustment of the nozzle holders  60  in the nozzle beam  59  for changing the spray pattern of the individual spray nozzles, wherein a rotary drive for each nozzle holder  60  or a common rotary drive for several nozzle holders can be used. 
     In the further embodiment illustrated in FIG. 10 of a spray nozzle  79  with rotary slide valve  69 , the extended spray head  64  is threaded onto the forward end  66  of the nozzle holder  60 . In the nozzle head  64  two diametrically oppositely arranged inlet openings  74  are provided which cooperate with two inlet openings  73  in the area of the blind bore  72 , that is open toward the antechamber  68  of the nozzle head  64 , of the rotary slide valve  69 , wherein the rotary slide valve  69  is centrally supported in the antechamber  68  of the nozzle head  64 . 
     As a result of the small rotary stroke of the rotary slide valve  69 , the spray nozzles  11 ,  79  are characterized by a fast control of the opening and closing processes which contributes to an optimal flatness control for thin strip and foil strip. 
     While specific embodiments of the invention have been shown and described in detail to illustrate the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.
A cooling and lubricating device for a cold rolling mill has nozzle beams with spray nozzles for individual rollers that are moveable relative to the rollers independently of one another transverse to the strip running direction. Rotary and linear drives are connected to the nozzle beams for rotating them about the longitudinal axis and moving them longitudinally. The nozzle beams are movable from a maintenance position to a working position and back. The spray nozzles have nozzle holders mounted in openings of the nozzle beams and nozzle heads mounted in the nozzle holders. Rotary slide valves with control members are rotatably supported in center throughbores of the nozzle holders. The rotary slide valves have blind bores opening to the nozzle heads and inlet openings aligned with inlet openings of the nozzle holder or nozzle head, when the spray nozzle is open, and covered by the nozzle holder or nozzle head, when the spray nozzle is closed.