Abstract:
A device for cooling rolled stock, preferably for cooling during cold rolling, including a nozzle for applying a cooling medium to the rolled stock, wherein a cooling chamber that is in fluid communication with the nozzle and extends substantially parallel to the strip running plane is provided for applying the cooling medium to the rolled stock.

Description:
The present application is a 371 of International application PCT/EP2013/074751, filed Nov. 26, 2013, which claims priority of DE 10 2012 223 848.4, filed Dec 19, 2012, the priority of these applications is hereby claimed and these applications are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     The present invention pertains to a device for cooling rolled stock, preferably in a rolling train. 
     PRIOR ART 
     Devices and methods for cooling rolled stock in a rolling train are well known. During the production of strip and sheet in rolling trains, the control and management of the metal temperature is of the greatest importance for various reasons. In the process of the hot-rolling of steel strip or of heavy plate, the microstructure of the rolled stock can be converted, after the final rolling, into a wide variety of different states by careful temperature control; such states can comprise ferritic, pearlitic, bainitic, or martensitic components. This temperature control is implemented by cooling devices downstream from the finishing trains, of which there are various known configurations. 
     Cooling sections for influencing the rolled stock in similar ways are also known for other materials such as aluminum, copper and copper alloys, magnesium, titanium, nickel, and other metals. 
     In cold-rolling trains for steel or other metals, the rolled stock heats up as a result of the rolling energy introduced into it as it is being formed. Here, too, certain damaging temperature ranges for the rolled stock must be avoided. In the case of steel, for example, this is the temperature range of blue brittleness. Coarse grains, furthermore, tend to form in certain materials at elevated temperatures. Cooling devices are thus also used in cold-rolling mills for strip. 
     When a rolling oil is used such as kerosene, which tends to self-ignite and which can ignite very quickly, the temperature of the rolled stock must again be controlled to prevent such ignition. 
     In this connection, spray cooling systems, for example, are known, which apply a coolant onto the strip by means of nozzles. A cooling device of this type is known from EP 1 527 829 A1, for example, which introduces the coolant onto the rolled stock through nozzles. 
     In addition, JP S63-101017 discloses a cooling device for cooling hot strips. Here, cooling water under high pressure is sprayed directly on the strips. In this spray cooling, to prevent the water sprayed on the strip from splashing in the surrounding area unhindered, and to selectively remove the sprayed water, the cooling device on the one hand includes plates to carry away the water arranged parallel to the strip and on the other hand drainage rollers arranged underneath the strips. The plates to carry away the water present an uncontrolled flow away, i.e., drainage, of the cooling water in an area under the cooling device. The dripping coolant heads to a lower drainage roller, which collects coolant that adheres to the bottom of the strip. Through an upper drainage roller, the coolant on the upperhalf of the strip is skimmed and is directed to an upper plate for carrying away the water. 
     Laminar cooling systems are also known, which conduct a jet onto the rolled stock at almost no pressure. According to DE 197 18 530 A1, furthermore, a cooling device operating by concurrent flow especially for hot wide strip is known, in which the intensity of the cooling is controlled by the coordination of independently adjustable parameters (cooling time, volume flow rate, pressure, etc.). To avoid unstable film evaporation, a safety interval from the boiling point of the coolant is maintained. 
     Also known are intensive cooling systems, Mulpic systems, intermediate stand cooling units, laminar cooling sections for hot strip production, as well as spray cooling systems. These systems are often encapsulated so that the drainage of the coolant can be controlled. 
     The disadvantage of the previously known solutions is that the coolant is conducted in the form of a jet onto the sheet or strip or other rolled medium and strikes that material with a certain kinetic energy. At the point of impact of the jet on the rolled stock, a large amount of heat transfer occurs. The jet, however, breaks down completely, and the kinetic energy of the jet is lost. From what is left of the jet, a chaotic off-flow of coolant forms, which has a significantly weaker cooling effect on the strip. 
     The jet of coolant breaks down in an uncontrolled manner and is distributed in various directions. In the case of rolled stock which is traveling slowly, the coolant drains off in the direction of the jet. In the case of a fast-traveling strip, however, the coolant is carried along with the strip. The presence of coolant outside the cooling device, however, is usually undesirable, because a strip coated with coolant can slip from the deflecting rolls, can contaminate the rolling hall itself, can contaminate the strip, can be the source of various emissions such as odors and aerosols, can interfere with measuring instruments, and can have a disadvantageous effect on the effort to achieve the tribologically correct conditions for the rolled stock in the roll gap. 
     The known cooling devices are thus sealed off by contact with rolls and seals or the like to avoid the entrainment of coolant into other areas of the plant, as disclosed in DE 28 44 434 A1, for example. 
     SUMMARY OF THE INVENTION 
     Against the background of the prior art described above, the goal of the present invention is to provide a device for cooling rolled stock which comprises a more uniform heat transfer and reduces the contamination of the surroundings. 
     Thus the device for cooling rolled stock, preferably for cooling during cold rolling, comprises a nozzle for applying a coolant to the rolled stock. According to the invention, a cooling chamber for applying the coolant to the rolled stock is provided, this chamber being in fluid communication with the nozzle and extending parallel to the strip passline, the device comprising an adjusting device for reversing of flow direction of the coolant in the cooling chamber by moving an outer shroud of the device, the sheath is movable from the first position to a second position, so that based on a setting of the sheath, two feed lines and two chain lines are connected so that the flow direction is changeable. 
     Because the cooling chamber is configured to extend along the rolled stock, i.e., along the strip passline, for application of the coolant to the rolled stock, the coolant is guided in a defined manner. If the cooling chamber is configured appropriately, it is also possible to prolong considerably the time during which the coolant can act on the rolled stock; this action is geometrically defined, furthermore, and can be executed in controlled fashion. 
     Uncontrolled runoff of the coolant from the rolled stock is also suppressed, so that an undesirable intrusion of coolant into other areas of the plant can be reduced. 
     In contrast to spray cooling systems, it is also possible significantly to increase the surface onto which the coolant acts, because the cooling channel makes it possible to supply coolant to a geometrically defined area. 
     The backspray which occurs when the coolant strikes the rolled stock is also avoided in the manner according to the invention. Because of the effective guidance of the coolant along the rolled stock, furthermore, the pressure level of the coolant can also be reduced, as a result of which energy savings can be achieved, because the coolant does not have to be put under such high pressure. 
     The cooling chamber is preferably positioned between the rolled stock and a chamber roof. In this way, direct contact between the cooling fluid and the rolled stock is achieved, and variations in the distance between the chamber roof and the rolled stock can be easily compensated by the adjusting the volume flow rate. 
     The nozzle is preferably configured in such a way that the coolant can be directed into the cooling chamber as an essentially uniform flow. As a result of the formation of the uniform flow, a uniform heat transfer distribution can be achieved. 
     A slit nozzle can be considered an especially suitable form of nozzle, which comprises a gap of constant size across the width of the cooling chamber. 
     The transition from the nozzle to the cooling chamber is preferably provided with a separation edge, which, for example, can be realized in the form of a height offset between the nozzle gap and the cooling chamber roof. This prevents the supplied fluid flow from adhering to the cooling chamber roof upon emergence from the nozzle gap or from preferentially following the roof instead of leaving the nozzle gap in the desired direction toward the surface of the strip and thus filling the cooling chamber. 
     The cooling chamber is preferably configured in such a way that the coolant can flow through the cooling chamber as an essentially uniform flow. It is especially advantageous here for the cross section of the cooling chamber to be essentially constant in the strip travel direction. Thus, as a result of the uniform flow in the cooling chamber, uniform cooling over the entire contact surface can be achieved. Such uniform cooling would no longer be present if vortices were to form. 
     In another preferred elaboration, the cooling chamber extends in the direction opposite to the strip travel direction, so that the coolant is conducted in the direction opposite to that in which the strip travels. It is especially preferred in this connection for the nozzle to be situated behind the cooling chamber, i.e., downstream from it with respect to the strip travel direction. As a result of this countercurrent cooling, especially effective use of the coolant is achieved. In particular, the coolant is used first at the coldest area of the rolled stock and then flows to the hotter areas of the rolled stock, as a result of which optimal heat transfer occurs in all areas. 
     The cooling chamber can comprise at least one cooling chamber roof extending parallel to the rolled stock and preferably at least one side wall perpendicular to the rolled stock and extending in the strip travel direction to form a lateral boundary of the cooling chamber. Thus the cooling chamber can be easily constructed. 
     In another preferred elaboration of the cooling device, a flow brake in the form of, for example, a sealing strip can be installed a certain distance away from the outlet end, where the flow leaves the cooling chamber, or a similar measure for constricting the cooling chamber can be provided to prevent the fluid from freely leaving the cooling chamber. 
     To adapt the cooling chamber to different strip widths of the rolled stock to be cooled, the device in a preferred form has at least one adjustable side wall, which is positioned at a defined distance from the strip width of the rolling stock to be cooled. As a result, the flow in the cooling chamber is guided with optimal fashion, and the formation of vortices is prevented. 
     So that the coolant can be removed from the rolled stock, the cooling chamber can be followed in the flow direction by a drainage chamber for removing the coolant from the rolled stock. It is especially preferred in this connection for the drainage chamber to be larger than the cooling chamber, so that the flow velocity of the coolant is slower in the drainage chamber than in the cooling chamber. 
     In a preferred elaboration, the supply of coolant to the nozzle can be automatically controlled, preferably by means of a controllable pump unit, and the supply of coolant is determined as a function of various parameters of the rolled stock, preferably as a function of the temperature of the rolled stock, the material of the rolled stock, and/or the residual fluid on the rolled stock after passage through the device. 
     So that the rolled stock can be threaded in, the cooling chamber can be swung away from the plane of the rolled stock. 
     To protect other plant components from contamination, at least one removal device, i.e., a device for removing excess coolant from the rolled stock, can be provided outside the cooling chamber, preferably in the form of an air-blast device, a spray device, a suction device, a transverse air-blast device, and/or a blower. 
     Preferred exemplary embodiment and aspects of the present invention are explained in greater detail in the following description of the figures: 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         FIG. 1  shows a schematic diagram of a rolling train with rolling stands and devices for cooling; 
         FIG. 2  shows a schematic diagram of a reversing stand with a device for cooling; 
         FIG. 3  shows a device for cooling rolled stock with a cooling chamber; 
         FIG. 4  shows the device for cooling according to  FIG. 3  with a detailed illustration of the flow relationships; 
         FIG. 5  shows a comparison between the heat transfer in a device for cooling rolled stock as proposed above and that of a conventional spray cooling system; 
         FIG. 6  shows a schematic diagram of an especially advantageous embodiment of the transition between nozzle and cooling chamber; 
         FIG. 7  shows a schematic diagram of a preferred embodiment of the strip cooling system with adjustable side walls for adapting the chamber to the width of the strip; 
         FIG. 8  shows a schematic diagram of a preferred embodiment of the strip cooling system with a flow brake at the outlet where the flow leaves the cooling chamber; 
         FIG. 9  shows a schematic diagram of another exemplary embodiment of a device for cooling rolled stock; 
         FIG. 10  shows a device for cooling rolled stock together with a drainage chamber; 
         FIG. 11  shows a device for cooling rolled stock with a drainage chamber on both sides of the strip; 
         FIGS. 12 a  and 12 b    show diagrams of a device for cooling a strip with a drainage chamber, which can be adjusted as a function of the strip travel direction; 
         FIG. 13  shows a schematic diagram of how the cooling device can be opened so that the strip can be threaded in; 
         FIG. 14  shows another device for cooling rolled stock with removal devices on both sides serving a barrier function and with a deflector plate; and 
         FIG. 15  shows a schematic diagram of a control unit together with the device for cooling rolled stock. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     In the following, preferred exemplary embodiments are described on the basis of the figures. Elements which are the same or similar or which function in the same or a similar way are designated by the same reference numbers, and in some cases the description of these elements is not repeated to avoid redundancies in the description. 
       FIG. 1  shows a schematic diagram of a rolling train with several rolling stands  1 , by means of which the rolled stock  2  is rolled thinner. Schematically illustrated cooling devices  3  for cooling the rolled stock  2  are located in front of the first stand, behind the last stand, and between the stands. 
       FIG. 2  shows another rolling train, in this case with a reversing stand  1 , also shown schematically, in front of and behind which are cooling devices  3  for cooling the rolled stock  2 . 
     It is immediately clear from  FIGS. 1 and 2  that the cooling device  3  can be arranged at any desired point, i.e., in front of the rolling stand  1  in question, between rolling stands, or behind the rolling stand in question. There is therefore a corresponding freedom with respect to the arrangement of the cooling devices  3 , which can be placed wherever they best serve the purpose of the specific rolling process in question. 
       FIG. 3  shows a schematic diagram of a cooling device  3 , which is supplied with coolant through a feed line  30 . The feed line  30  is provided with a diffusor, so that the coolant  34  can be introduced uniformly into a nozzle  32 , which surrounds the diffusor. 
     In the case of the schematically illustrated nozzle  32 , because of the geometry of the nozzle  32 , in particular because of an appropriate constriction, the coolant  34  is formed into a uniform, accelerated flow, in which form it then leaves the nozzle  32 . 
     Following the nozzle  32  is a cooling chamber  4 , which extends essentially parallel to the plane  10  defined by the rolled stock  2 , also called the strip passline, the chamber being configured to apply the coolant  34  to the rolled stock  2 . After the rolled stock  2  has been threaded into it, the cooling chamber  4  thus extends also essentially parallel to the rolled stock  2 . In the cooling chamber  4 , the coolant  34  flows out of the nozzle  32  and comes in contact with the rolled stock  2 . Thus there is a transfer of heat from the rolled stock  2  to the coolant  34 , at least in the area of the cooling chamber  4 . As will be described further below on the basis of  FIG. 5 , the rolled stock  2  is cooled very effectively as a result of the long and defined contact time of the coolant  34  with the rolled stock  2 —especially as compared to the effectiveness of simply spraying the rolled stock  2 . 
     The cooling chamber  4  consists essentially of a chamber roof  40 , which preferably follows immediately after the nozzle  32 . The chamber roof  40  is arranged opposite the top surface  20  of the rolled stock  2 , so that the coolant  34  flowing through the nozzle  32  is conducted from the nozzle  32  into the cooling chamber  4 , in which the coolant  34  then flows along the rolled stock  2  in a manner essentially free of vortices. 
     The thick arrow indicates the strip travel direction W of the rolled stock  2 . It can be seen immediately that the cooling chamber  4 , starting from the nozzle  32 , is oriented in the direction opposite to the strip travel direction. In other words, the nozzle  32  is arranged downstream, with respect to the strip travel direction W, from the cooling chamber  4 . 
     The cross section of the cooling chamber  4  is essentially constant in the strip travel direction, so that the flow velocity of the coolant  34  in the cooling chamber  4  is essentially constant, and simultaneously an essentially vortex-free flow can also be formed. As a result, the coolant  34  comes in contact with the rolled stock  2  in the area of the cooling chamber  4  in such a way that an efficient and uniform flow without vortices is present here. 
     At the end of the cooling chamber  4 , the coolant  34  emerges as a diffuse flow and can be collected in the usual way. 
       FIG. 4  shows the structure of the cooling device  3  schematically illustrated in  FIG. 3  once again in detail, especially with respect to the flow relationships. The strip travel direction W of the rolled stock  2  is again indicated by the thick arrow. 
     The velocity distribution of the flow within the cooling chamber  4  is shown schematically. The diagram at the bottom left shows the largely symmetric velocity profile of the flow without a moving strip, i.e., at zero strip velocity. With a moving strip or a non-zero strip velocity, an asymmetric velocity profile is obtained, as shown in the diagram at the bottom right. As a result of the movement of the strip, the relative velocity between the flow and the surface of the strip is increased, which amplifies the cooling effect, that is, the transfer of heat from the surface of the strip to the coolant. 
     The nozzle  32  is configured in such a way that a uniform flow velocity across the entire cooling chamber  4  is obtained. 
       FIG. 5  shows a comparison between the cooling device  3  as shown in  FIGS. 2 and 3  and a conventional spray device  3 ′. In the cooling device  3  according to  FIGS. 2 and 3 , an essentially uniform flow is formed, which is conducted through the cooling chamber  4 . It is thus possible to achieve the heat transfer shown schematically under this device in the area of the cooling chamber  4 . Thus a constant heat transfer is obtained on the surface  20  of the rolled stock  2 , as can be seen from the schematic diagram underneath. 
     In contrast, the spray device  3 ′, as indicated by the arrows, results in a large amount of swirling and a considerable amount of coolant backspray. The resulting cooling action is thus evident only at individual points, as can be seen from the schematic diagram. 
       FIG. 6  shows a schematic diagram of a preferred form of the cooling device  3 , in which, at the transition from the nozzle  32  to the cooling chamber  4 , a separation edge can be seen. This has the job of preventing the fluid flow from adhering to the roof of the cooling chamber and thus of conducting the flow to the surface of the strip and filling the cooling chamber more effectively. The separation edge in this example has been realized by an offset between the height of the nozzle gap and the roof of the chamber, so that the distance between the chamber roof and the strip surface is greater than the height H of the nozzle gap above the strip surface. 
       FIG. 7  shows another preferred embodiment of the cooing device, in which the width of the cooling chamber  4  is adapted to the width of the strip material currently being processed. In the example shown, this is accomplished by shifting the two side walls of the cooling chamber  4 , which are essentially parallel to the strip width. The side walls in  FIG. 7  are shown in dash-dot line; they can be shifted in the direction of the double arrows. Adjusting the width of the channel ensures optimal guidance of the flow along the rolled stock and suppresses the formation of vortices. The distance between the edge of the strip and the side wall of the cooling chamber is in the range of 2-100 mm, and preferably in the range of 10-50 mm, wherein the channel width may be less than 10% greater than the strip width of the rolled stock. 
       FIG. 8  shows another preferred embodiment of the cooling device, in which a flow brake in the form of, for example, a sealing strip a certain distance away from the strip surface or in the form of a similar cooling chamber constriction prevents the free outflow of the coolant from the cooling chamber. 
       FIG. 9  shows another embodiment of a cooling device  3 , wherein a cooling device  3  of the type already shown by way of example in  FIGS. 2 and 3  is now arranged on both sides of the rolled stock  2 . Thus the top surface and also the bottom surface of the rolled stock  2  can now be cooled. 
       FIG. 10  shows another embodiment of a cooling device  3 , wherein again the arrangement of nozzle  32  and cooling chamber  4  already familiar from the preceding exemplary embodiments is provided. Following the cooling chamber in the flow direction is now a drainage chamber  5 , which is configured to collect the coolant  34  flowing through the cooling chamber  4  and to carry it away. 
     The drainage chamber  5  is configured so that it is connected to the chamber roof  40  of the cooling chamber  4  and provides a collecting volume  50 , in the side of which a drain opening  52 , shown schematically, is arranged. The coolant  34  flows into the drain opening  52  and cannot contaminate the surroundings or the rolled stock  2 . It is also easy in this way to recirculate the coolant  34 , because, after it has been sent through the feed line  30  and the nozzle  32  and brought into contact with the rolled stock  2 , it can then be removed from the rolled stock  2  via the drainage chamber  5 . 
       FIG. 11  shows a corresponding configuration, in which again a corresponding device with drainage device is shown on both the top and the bottom sides of the rolled stock  2 . 
     In  FIG. 12 , another device for cooling rolled stock  2  is provided, wherein again the device for cooling is provided with the nozzle  32 , the cooling chamber  4 , and the drainage chamber  5 . By means of adjusting cylinders  6 , the outer shroud  7  of the device can be manipulated in such a way that the flow direction of the coolant  34  can be changed. This is important when the direction in which the strip is traveling is reversed, as in the case of a reversing stand, for example. 
     For this purpose, the outer shroud  7  is pushed from the first position, shown at the top at  12   a , into a second position, shown at the bottom at  12   b . Thus two feed lines  30  and two drains  52  are provided, which are connected to each other as necessary, depending on the position of the outer shroud  7 , to achieve the desired flow of the coolant  34 . 
       FIG. 13  shows in general how the entire device can be swung away from the top and from the bottom of the rolled stock  2 , i.e., from the passline  100 , so that the stock can be threaded in more easily or so that maintenance work can be carried out more conveniently. 
       FIG. 14  corresponds in principle to the exemplary embodiment shown in  FIGS. 7 and 8 . Upstream and downstream, in the strip travel direction W, from the cooling chamber, there is in each case an air-blast device, also called a removal device, as indicated schematically in the form of the blast nozzles  75 . Upstream and downstream, in the strip travel direction W, from the cooling chamber  4  with nozzle  32  and drain chamber  5 , there is in each case a removal device with barrier function and deflector plate  73 , also shown schematically. The removal device protects adjacent systems from contamination. The blasts or backsprays discharged by the removal device, furthermore, can also provide a barrier function, and the off-flow of the escaping fluid can be optimized by the deflector plates. The blasts or backsprays keep the coolant  34  in the cooling chamber  4  or drive escaping coolant  34  back into the cooling chamber  4 . The deflector plate collects escaping coolant and conducts it effectively away. 
     In this way, other areas of the plant can be protected from contamination with coolant  34 . 
       FIG. 15  shows a schematic diagram of the automatic control mechanism for the present device for cooling rolled stock. In particular, the rolled stock  2  is guided through a rolling stand  1  and then treated with coolant  34  in a cooling device  3 . The device for cooling the rolled stock  2  is supplied with the coolant by a pump circuit  8 . The pump circuit  8  comprises a suction line  80 , an automatically controlled pump  82 , a coolant drain line  84 , and a collecting tank/reservoir  86 . 
     The coolant is thus pumped from the collecting tank/reservoir  86  through the suction line  80  by means of the automatically controlled pump  82  into the device  3  for cooling rolled stock  2 . There the coolant  34  is brought into contact with the rolled stock  2 . Then the coolant is collected again by way of the drainage chamber  5  shown in the preceding figures and sent back to the reservoir/collecting tank  86  via the drain line  84 . 
     The automatically controlled pump  82  is actuated by an automatic control unit  100 . The control unit  100  comprises a controller  110 , which takes over the actual job of automatically adjusting the controllable pump  82  by adjusting its output, for example. The controller  110  is supplied with parameters  120 , which comprise, for example, a characteristic curve of the controllable pump  82  or other parameters relating to the geometric configuration of the cooling chamber  4 , to the different materials of the rolled stock  2 , to different pass sequences, to different velocities of the rolled stock  2 , etc. 
     The various parameters of the rolling process measured by sensors are evaluated by an evaluation unit  130 , on the basis of which the controller  110  is actuated. 
     In the evaluation unit  130 , sensors  140 ,  150 , for example, which are configured as residual fluid or temperature sensors, participate in the evaluation of the actual state of the rolled stock  2 . In addition, residual fluid sensors  140  can be used to monitor the correct functioning of the device for cooling rolled stock, so that residual fluid is not transported onward on the rolled stock  2  or is transported onward only within narrowly set limits. The temperature sensors can be used to adjust the cooling power of the device for cooling in such a way that the desired microstructure is obtained. 
     A speed sensor  160  is also provided, which determines the speed at which the rolled stock  2  is coiled. 
     The various parameters are evaluated in the evaluation unit  130  to obtain a uniform control command, which is then transmitted to the controller  110 . 
     Insofar as applicable, all of the individual features presented in the individual exemplary embodiments can be combined with each other and/or exchanged for each other without leaving the scope of the invention. 
     LIST OF REFERENCE SYMBOLS 
     
         
           1  rolled stock 
           10  strip passline 
           100  control unit 
           110  controller 
           120  parameter 
           130  evaluation unit 
           140  temperature sensor 
           150  residual fluid sensor 
           160  speed sensor 
           2  rolled stock 
           20  surface of the rolled stock 
           3  cooling device 
           3 ′ nozzle 
           30  feed line (with diffusor) 
           32  nozzle 
           34  coolant 
           4  cooling chamber 
           40  cooling chamber roof 
           45  flow brake 
           5  drainage chamber 
           50  volume of the drainage chamber 
           52  drain opening 
           6  adjusting cylinder 
           7  outer shroud 
           73  deflector plate 
           75  blast nozzles 
           8  fluid circuit 
           80  suction line 
           82  automatically controlled pump 
           84  coolant drain line 
           86  reservoir 
         W strip travel direction