Roller device

20180043426 ยท 2018-02-15

    Inventors

    Cpc classification

    International classification

    Abstract

    A roller device assembly, in particular for forming a strand guiding section (100) of a casting machine includes at least two roller devices each having a cross beam (30) and at least one roller element (10) supported on the cross beam (30) by means of roller bearings (20, 22), wherein guiding means for at least three different media are provided in the cross beam (30).

    Claims

    1. Roller device assembly, comprising two roller devices (1) for forming strand-guiding segments (100) of a caster and mountable in a segment frame of the caster as a pre-assembled module adjacent to each other, each roller device comprising a cross-beam (30), at least one roller element (10) supported on the beam; roller bearings (20, 22) for supporting the at least one roller element, and conduit elements (310, 320, 330, 340, 350) provided on the cross-beam (30) of each roller device for at least three different media, wherein at least one of the conduit elements is provided in the form of a channel (52) on a rear side 38 of the cross-beam (30), wherein the cross-beams (30) of the adjacent roller devices extend side-by-side along their longitudinal extent, and wherein cover means in form of a reclosable roof or silicone is provided for closing respective channels (52).

    2. A roller device assembly according to claim 1, wherein each roller device comprises at least one medium connector (40, 42, 44) communicating with the at least one of the conduit elements and provided on an end side (32) of the cross-beam, on a longitudinal side (36) of the cross-beam, or on a rear side (38) of the cross-beam (30).

    3. A roller device assembly according to claim 2, wherein the at least one medium connector (40, 42, 44) is formed as one of a socket, a coupling, a connector element, a hybrid socket, a water board with a gasket, a connection pipe with O-rings on both sides, or a data bus socket.

    4. Roller device assembly according to claim 2, wherein the at least one medium connector is arranged on the longitudinal side (36) of the cross-beam (30) and is so arranged that it can communicate with a corresponding medium connector (42, 44) in the cross-beam of an adjacent roller device (1), providing a direct connection of the medium connectors in both cross-beams of the corresponding roller devices.

    5. A roller device assembly according to claim 1, wherein the conduit elements comprise at least two conduit elements (310, 320, 330, 340, 350), respectively, for conducting at least two of the following media: cooling medium for inner cooling of the roller, cooling medium for secondary cooling, hydraulic medium for a hydraulic control circuit (342), compressed air medium for a pneumatic control circuit, power medium for an electrical power supply, power medium for electrical control signals, power medium for electrical measurement signals, power medium for optical measurement signals or electrical and/or optical bus system (352), and wherein medium connectors (40, 42, 44) are provided on an end side (32) of the cross-beam (30), a longitudinal side (36) of the cross-beam (30), and/or a rear side (38) of the cross-beam (30) for communicating with respective conduit elements, wherein the medium connectors (40, 42, 44) are formed as a socket, a coupling, or a connector element, and wherein a single socket, a single coupling, or a single connector element communicates at least two media with the cross-beam.

    6. A roller device assembly according to claim 1, wherein the roller device and the adjacent roller device are provided in the segment frame. A roller device assembly according to claim 1, wherein at least one of the cross-beams (30) has an extension in a cast direction that forms, with the cross-beam of another adjacent roller device, a roof of a cooling chamber, and contacts the cross-beam of the another adjacent roller device substantially without any clearance.

    Description

    BRIEF DESCRIPTION OF THE PREFERRED EMBODIMENTS

    [0043] FIG. 1 shows a schematic perspective view of a roller device having a plurality of roller elements supported on a cross-beam by roller bearings;

    [0044] FIG. 2 shows a schematic side view of a segment on the loose side and which carries seven roller devices;

    [0045] FIG. 3 shows both loose and fixed sides of the segment shown in FIG. 2;

    [0046] FIG. 4 shows a schematic detailed side view of the segment shown in FIG. 2;

    [0047] FIG. 5 shows a schematic perspective view of several roller devices arranged in a row one after another;

    [0048] FIG. 6 shows a schematic side cross-sectional view of the arranged in a row, roller devices shown in FIG. 5;

    [0049] FIG. 7 a cross-sectional view of the roller device shown in FIG. 1;

    [0050] FIG. 8 shows a layout for inner cooling of rollers;

    [0051] FIG. 9 shows a layout for cooling of intermediate bearings;

    [0052] FIG. 10 shows schematically a first embodiment of the secondary cooling with an external feeding;

    [0053] FIG. 11 shows schematically a second embodiment of the secondary cooing with feeding conduits arranged in the cross-beam;

    [0054] FIG. 12 shows schematically the secondary cooling with two different feeding arrangements for controlling the application width

    DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

    [0055] Below, the present invention will be described in detail on basis of the drawings. In the description, the same elements in the figures are designated with the same reference numerals, and partially, a repeated description of the respective elements is avoided.

    [0056] FIG. 1 shows a schematic perspective view of a roller device 1 having roller elements 10 which are respectively supported in roller bearings 20, 22. To this end, two roller bearings 22 are provided on respective outer sides of the roller device, with bearings 20 provided as intermediate bearings. The bearings 20, 22 are connected with a cross-beam 30, so that the roller elements 10, the bearings 20, 22, and the cross-beam 30 form a module. The cross-beam 30 extends in the direction of the roller axes of the roller elements 10. The modular roller device 1 can be pre-assembled and pre-adjusted in a manner shown in FIG. 1, so that the roller device can be fitted in an above-arranged machine unit, e.g., a segment of a casting machine.

    [0057] The cross-beam 30 is provided on its end side 32 with a medium connector 40 communicating with conduit elements for a first medium circuit for cooling the bearings 20, 22, a second medium circuit for inner cooling of roller elements 10, and a third medium circuit for feeding lubricant to the bearings 20, 22. Such a medium connector 40 is likewise provided on opposite end side 32 of the cross-beam 30. Dependent on the construction. Feeding of the cooling medium for cooling circuits can be provided on one side and on the opposite side, removal of the cooling medium can be carried out. Alternatively, on one side of the cross-beam both feeding and removal can be provided for a section of the cross-beam and on the other side, feeding and removal can be carried out for a respective other section of the cross-beam.

    [0058] Another medium connector 42 communicates with a conduct element provided in the cross-beam for spraying water that serves as a cooling medium for the secondary cooling. For secondary cooling, water is applied to a slab from nozzles 50 provided on the cross-beam. The medium connector 42 which communicates with a conduit element for the secondary cooling, in this embodiment, is provided on the longitudinal side 34 of the cross-beam. In another embodiment, the medium connector 42 can also be used for cooling of bearings or for inner cooling of rollers. This depends, among others, o the layout of conduit elements provided in the cross-beam.

    [0059] A further medium connector 44 in form of data buses is provided on the longitudinal side 34 of the cross-beam 30. In the roller device 1, sensors are provided for measurement of different operational parameters, e.g., for measuring the cooling medium temperature in different points of the roller device, the load to which the bearings are subjected, the bearing temperature, the strand temperature, the flow rate, the pressure, humidity, etc. Further, switching devices an be provided for turning on and off, e.g., different sections of the secondary cooling. With the media connector 44, corresponding signals of the sensors and the corresponding switching command can be transmitted, as well as power supply for the sensor and switches.

    [0060] Different media, e.g., cooling medium for the first cooling circuit for bearing cooling, cooling medium for the second cooling circuit for cooling roller elements 10, water for the third cooling circuit for secondary cooling of slabs, lubricant for lubricating the bearings 20, 22, hydraulic medium or compressed air medium for hydraulic or pneumatic control, data lines, switching lines, sensor lines, and power supply for the sensors and switches located in the roller device, all are guided within the cross-beam 30. This is achieved, e.g., by formed corresponding deep hole bores in the solid material of the cross-beam in order to pass signal wires through these deep hole bores. In order to be able to form deep hole bores at large cross-beam width, the bores can be formed from opposite sides. Liquid and gaseous media, e.g., cooling medium for the roller bearing cooling circuit and the circuit for inner cooling of rollers, can likewise be guided through deep hole bores within the cross-beam 30. The lubricant also can be guided in such deep hole bores.

    [0061] In an alternative embodiment, the conduit elements for the media extend in a media channels milled in the solid material of the cross-beam which are closed with a cover. The availability of milled cooling media channels, which are closed with a cover, has an advantage that the cooling media channels can be easily opened for maintenance purposes and, correspondingly, can be cleaned. With deep hole bores, this cannot be easily done. Also, signal lines, control lines, and power supply lines can be easily put in so milled channels. Moreover, the milled media channels enable an easy access to separate sensor positions.

    [0062] The channels for lubricant that is fed to roller bearings 20, 22 can also be formed as deep hole bores or as channels which are milled in the cross-beam and are closed with covers. In this regard, it is advisable to form, for each of the roller bearings, its own lubricant channel so that the lubricant, e.g., oil-air mixture, which is fed from a lubricant distributor, can be separately delivered to respective separate bearings 20, 22.

    [0063] While in the embodiment of the roller device 1 shown in FIG. 1, all of the media are guided in the cross-beam, obviously, it is also possible to guide only a portion of the media in the conduit elements inside the cross-beam, and individual media outside of the cross-beam, as known in the state of the art. The decision here is based, among others, on the desired shape of the cross-beam, in particular, its volume. That goes without saying that in a cross-beam having a relatively small volume, only a limited number of media channels can be formed. However, with regard to the present invention, also conduit elements extending along the cross-beam and fixedly connected therewith, should be viewed as located in the cross-beam. In this connection, the conduit elements should be seen as belonging to the cross-beam. E.g., if a conduit element is provided in form of a channel extending along the cross-beam and fixedly connected therewith, this conduit element is seen as being located in the cross-beam. Also, a medium conduit extending along the cross-beam and connected therewith, e.g., a control line for transmitting electrical or hydraulic control signals, is seen as located in the cross-beam.

    [0064] In this connection, it is essential that either conduit elements for at least three different media are located in the cross-beam, e.g., channels for the cooling medium for bearings, channels for the cooling medium for roller cooling, and bores for feeding lubricant, or at least one conduit element is provided in the cross-beam for a new medium, e.g., cooling medium for inner cooling of rollers, cooling medium for secondary cooling (one-component material or two-component material), hydraulic medium for a hydraulic control circuit, compressed air medium for a pneumatic control circuit, power medium for power supply, power medium for control signals, power medium for electrical measurement signals, power medium for optical measurement signals or electrical or optical bus system.

    [0065] Correspondingly, a greater portion of the media that before was fed by separate tubular conduits from outside, is only delivered to their respective predetermined locations through corresponding channels and bores in the cross-beam 30. The advantage of this during the mounting of the roller device/consists in that not so many working steps are necessary for mounting of the roller device 1 because it can be mounted as a module. By mounting as a module, in particular, as a complete pre-assembled, pre-tested, and pre-adjusted module, after the securing of the module on a support, only respective media feeding means must be connected with media connectors provided on the module. The corresponding connection can be provided automatically already upon putting the cross-beam on the support. This can be carried out by a junction connector, e.g., socket, coupling, or connection elements or the like without any problem.

    [0066] On the other hand, separate conduit elements in the cross-beam are better protected against mechanical failures, breaking through, and other damages that may occur during the operation of a roller device. Thereby, the reliability is noticeably increased. In addition, the module can be tested and adjusted before being mounted.

    [0067] Dependent on respective used media and dependent on a respective field of use of respective roller devices 1, the corresponding connectors 40, 42 and 44 can be arranged on the cross-beam in different positions. The exemplary arrangement shown in FIG. 1, is then advantageous when separate roller devices 1 are mounted in a machine unit, e.g., in a form schematically shown in FIG. 5, side-by-side or with cross-beams 30 adjoining one another to form a corresponding segment. In this case, as it further would be explained in detail with reference to the embodiment shown in FIG. 5, the arrangement of at least the connector 42 for the secondary cooling medium and the connector 44 for the data bus on the longitudinal side 34 of the cross-beam is advantageous. Thereby, in case when the separate cross-beams are placed next to each other, the connection of respective medium circuits with each other can be achieved quasi automatically. In other words, with cross-beams arranged in a row adjacent to each other, some conduit elements can be dispensed with by undertaking separate wiring and piping steps. Alone, by placing respective cross-beams next to each other, the respective connection of the conduit elements by corresponding connectors is achieved. In this way, even more efficient mounting can be achieved, and the connections or the connectors between separate medium conduits in separate cross-beams are arranged in a secure position in a protective manner between the cross-beams.

    [0068] In this embodiment, separate media connectors are corresponding seriesly connected. Such series connection is completely without problems, e.g., in case of bus lines because here, a very large number of signals can be communicated to the same bus. In case of a secondary cooling, the series connection is likewise possible without problems, because the secondary cooling medium along the casting direction is not substantially heated, and a continuous flow of the secondary cooling medium from the first to the last roller device of a segment can be provided.

    [0069] With regard to cooling of the roller bearings 20, 22 and cooling of the respective roller elements 10, such a series connection of roller devices 1 is also possible. Here, however, one should take into account that an increased amount of heat that should be removed by cooling. Correspondingly, with the series connection, it may so happen that for the last roller device in the corresponding series connection, no adequate cooling power is available, possibly because of already undertaking heating of the cooling medium. Correspondingly, in order to be able to make available adequate cooling power for each separate cooling device, in the embodiment of the medium connector 40 shown in FIG. 1 and which is provided on the end side 32, there are provided connectors for delivery of cooling medium for roller bearings 20, 22 and cooling medium for inner cooling of the roller elements 10 so that for each roller device 1, a separate cooling medium supply is available for these primary cooling circuits.

    [0070] It is further proposed to separately deliver lubricant to each respective above-mentioned roller bearing 20, 22, from lubricant supply for a respective roller device 1, which lubricant is fed from a lubricant distributor. Correspondingly, in the embodiment shown in FIG. 1, there are provided, on the end side 32 of the cross-beam 30, connectors for lubricant distribution.

    [0071] However, other arbitrary meaningful combinations and positions for respective medium connectors for feeding and removing media on the cross-beam 30 are possible, which can take into account other consideration. E.g., it is conceivable to provide the sockets and fluid connections not only in the end sections of the cross-beam 30 on the longitudinal side 34, but rather those can obviously be provided in the region of the inner cross-beam sections which, e.g., are designated with a reference numeral 3b. Even in such a case, by simply pushing the cross-beams 30 during mounting to form a larger unit, respective connectors and couplings can be quasi automatically connected with each other.

    [0072] In this regard, it can be suggested to place separate connectors on the rear side 38 of the cross-beam 30, i.e., on the side of the cross-beam 30 remote from the slab to thereby achieve both an advantageous layout of respective connectors for assembly purposes and also, e.g., to be able to make, e.g., shorter channels or deep hole bores, in the cross-beam. When the medium, e.g., is fed from outside of the rear side 38 in the middle region of the cross-beam 30, respective necessary extension lengths can be reduced by half.

    [0073] FIG. 2 shows a schematic side view of a section of a segment 100, wherein the loose side of the segment 100 is shown in the figure. A corresponding complementary device is provided on the fixed side, wherein here, correspondingly, likewise seven roller devices are provided. This is, e.g., is also shown in FIG. 3 which shows the loose side and the fixed side of the segment 100.

    [0074] The segment 100 has a segment frame 110 on which seven roller devices 1, which are similar to the roller device 1 shown in FIG. 1, are mounted. Respective media supplies and media connectors 40 are not yet closed by respective sockets or connection pieces in the condition of the segment 100 shown in FIG. 2. Further, media connections are located on the rear side of respective roller devices 1 so that they extend within the segment frame 110.

    [0075] Separate roller devices 1 are mounted on the segment frame 110, respectively, as a complete module. In other words, separate roller devices 1 need not be assembled on the segment frame of separate parts, but rather a pre-assembled roller device 1 that includes the cross-beam 30 and roller elements 10 pre-mounted thereon with aid of bearings 20, 22, is directly mounted, as a module, on the segment frame 110. After mounting of the roller devices 1 on the segment frame 110, a connection of respective media feeding conduits and media discharge conduits to coupling elements provided therefor must be timely carried out.

    [0076] In particular, a respective segment 100 can be formed by securing the roller devices on a respective segment frame with bolts and/or screws, wherein some of the media conduits become connected by placing the cross-beam on the segment frame. Other media conduits are become connected, after placing, using socket and coupling connections. Correspondingly, a cumbersome separate tubing and wiring of the cross-beams is eliminated. Obviously, the tubing and wiring of the segment frame are still carried out and are available.

    [0077] With the proposed integrated cross-beam, only casters with a small casting radius, e.g., from 4000 to 5000 mm can be formed, wherein the rollers also allow a small roller diameter, e.g., from 120 to 180 mm. With simple attachment of media to the rear side of the cross-beams or to an end side of the cross-beams, the connection of media is obtained even at these small radii. Previously, the small radii were not possible because an access for welding of respective media feeding conduit was not available.

    [0078] Advantageously, with the proposed shape of the cross-beams, also, putting of the cross-beams on support cross-beams in the segment frame can be eliminated because those are formed by the cross-beams themselves. Correspondingly, in the segment frame, each second or each third strut is eliminated, whereby the segment frames can be easily formed.

    [0079] An eventually damaged roller device 1 within the segment 100 can in this way be relatively simply and rapidly replaced because here, simply respective coupling or other connections are removed, and a modular roller device is inserted. The separate replacement of the roller device typically takes place after the entire segment in a respective strand guide has been removed. The replacement of the roller device then takes place in the segment workshop.

    [0080] Further, the so formed modular roller devices 1 can be held on a frame and quickly and efficiently be substituted for when needed. In addition, the error rate during mounting is smaller because the roller devices are already formed as self-containing systems that simply should be connected with provided to this end, coupling and connector elements.

    [0081] The operational reliability of the plant and the efficiency of the maintenance is further increased as each roller device 1, as a complete module, which has primary cooling circuit, lubricant circuit, secondary cooling, and data transmission elements, is completely formed, pre-tested, and pre-adjusted before installation. In particular, the roller layout already can be adjusted in the modular condition, so that alignment and adjusting works can be reduced to a minimum during the installation of the respective roller device 1 in segment 110.

    [0082] From the proposed construction, it follows that the accessibility of each roller device can noticeably be increased because a separate tubing completely or to a greatest extent can be eliminated as well as a separate wiring. In particular, all of the media and data conduits run inside the cross-beam that represents a self-containing unit, in particular then when they are milled out form a solid material. Thereby, the danger of strain fractures at a separate tubing due to different thermal expansion coefficients or different components is reduced because separate channels and deep hole bores are provided in a quasi monolithic cross-beam 30.

    [0083] FIG. 4 shows schematically a side view of a segment 100 wherein only one separate roller device 1 that has three roller elements 10 supported by respective roller bearings 20, 22, is visible. The secondary cooling with nozzles 50 which are shown by solid line extending over the width and which can apply cooling medium to the slab, is clearly shown. With control valves provided in the cross-beam, separate sections of the secondary cooling can be turned on and off.

    [0084] The media connectors 42 provided on a rear side 38 of the cross-beam 30, are shown in this semi-cross sectional view. It is further shown that feeding of the cooling medium for inner cooling of the rollers from the cross-beam 30 in the roller elements 10 takes place via side feeders 12 which are connected with the cross-beam and extend through the cover of the roller supports into the roller elements 10.

    [0085] FIG. 5 shows a further segment 100 wherein separate roller devices 1 adjoin each other side-by-side, with the cross-beams 30 being put up against adjacent beams along their longitudinal sections 34. In this way, it is immediately insured that the media connectors 42 for the cooling medium so adjoin each other that the flow of the secondary cooling medium through all of the roller devices is possible, without the need to carry out an additional external tubing. The same is the case with regard to data buses, wherein here the media connector 44 likewise are so arranged on the longitudinal side 34 that upon putting two roller devices 1 next to each other, an automatic electrical connection between respective data bus connectors 44 takes place.

    [0086] On the rear side 38 of the cross-beam 30, a milled-in cooling medium channel 52 is seen in FIG. 5. By mounting the cross-beams 30 on the segment frame 110, which is not shown in FIG. 5, or by providing a separate cover that covers the milled cooling medium channel 52, an easily accessible and maintenance-friendly cooling medium channel is provided and which is protected within the cross-beam 30 but, nevertheless, can be easily monitored. The shown cooling medium channel 52 represents conduit means for guiding the medium for cooling of bearings. In principle, such channel 52 milled-out in a solid material, can be formed for receiving every other medium, in particular for receiving electrical or hydraulic medium conduits.

    [0087] FIG. 5 further shows the formation of a roof of a tunnel cooling chamber with cross-beams 30 extending side-by-side, wherein the intermediate spaces 60 between the respective roller devices 1 or their cross-beams 30 are so filled with separate sheets 62 that here a quasi closing cover is provided on the loose side of the segment. In this way, water vapor which is formed in the tunnel cooling chamber, can be efficiently removed, without a need to provide an overdimensioned blower that should deal with a large amount of infiltrated air.

    [0088] Advantageously, the roof further includes additional covers which close, in particular, the channels 52 and which are secured with suitable mechanical means, e.g., with screws. Thereby, the rear side 38 of the cross-beams 30 is suitably sealed. As a result, a so-called reclosable roof is provided.

    [0089] Alternatively, the channel 52 can be covered when the roof, on the rear sides 38 of the cross-beams 30, is closed with silicon, whereby the channels 52 are suitably sealed.

    [0090] Also, instead of the separate sheets 62 which generally are formed by welded-in sheets provided on the segment, the cross-beam 30 itself can be so shaped that it adjoins an adjacent cross-beam so tightly along the entire casting width that a quasi universal cooling chamber is formed. To this end, the cross-beam should be so stretchable out and deformable in its transverse direction, i.e., in the casting direction that it forms, together with a respective adjacent cross-beam, as continuous structure as possible.

    [0091] FIG. 6 shows again a schematic cross-sectional view of a section of the segment of FIG. 5 and which clearly shows closing of the intermediate spaces 60 between separate cross-beams 30 with inserted sheets 62. In this way, a tunnel cooling chamber can be efficiently formed. As it has already been shown, the cross-beam 30 can so be formed in the casting direction that the inserts 62 can be eliminated as separate cross-beams adjoin each other clearance-free to a most possible extent.

    [0092] FIG. 7 shows a cross-sectional view of a roller device 1 in the region of the roller bearing 20. A cross-sectional view of the cross-beam 30 is likewise shown. In the cross-beam, three conduit elements 310, 320, 330 which are formed in the solid material of the cross-beam 30 as deep hole bores, are provided. The conduit elements 310, 320, 330 serve, in the embodiment shown, for conducting the cooling media and lubricant. The conduit element 310 serves for conducting of the lubricant for the bearing 20. The conduit element 320 transports the cooling medium for inner cooling of the roller. The conduit element 330 transports the cooling medium for cooling the bearing 20.

    [0093] In the cross-beam, there is further provided a conduit element 340 in form of a channel that opens to the back and is milled in the solid material of the cross-beam 30. A conduit 342 for hydraulic control is placed in the channel. Further, in the cross-beam 30, there is provided a conduit element 350 in form of a channel extending along the cross-beam 30 and fixedly connected therewith and in which a bus system 352 is located.

    [0094] Correspondingly, in the cross-beam 39 the conduit element 310, 320, 330, 340, 350 are provided for at least three different media.

    [0095] FIG. 8 shows schematically a layout of flows of the cooling medium for an inner roller cooling with a separate inflow for each cross-beam 30. The cooling media is fed in a corresponding conduit element in the cross-beam 30 via a distributor 400 and an associate medium connector 40. After the cooling medium passed through the rollers 10, it is picked up again by a distributor 420 provided on the opposite side and is removed. The process correspondingly is carried out for a row of separate roller devices.

    [0096] FIG. 9 shows an example of cooling of the roller bearing 20 in particular the middle bearing 20, analogous so that of FIG. 8. The cooling medium against is fed in respective cross-beams 30 via a distributor 410 and then is transported by the conduit element provided in the cross-beam 30 to the middle bearing 20 and then, by the conduit element to the outlet distributor 420.

    [0097] FIG. 10 shows schematically distribution of the cooling medium for the secondary cooling. The layout corresponds essentially to that shown in FIGS. 8 and 9, namely, the cooling medium for the secondary cooling is fed to the cross beams 30 via the distributor 410 and then to the nozzles 50 of the secondary cooling.

    [0098] FIG. 11 shows a variant of the secondary cooling, here, the cross-beams 30 are so arranged that they contact each other, and have conduit elements with medium connectors 42 corresponding to medium connectors 42 shown in FIG. 5. Correspondingly, by an arrangement of contacting each other cross-beams 30, it is achieved that the header 410 inside the cross-beams 30 is formed. Separate conduit elements for distributing the secondary cooling medium correspondingly branch from the header 410. In this embodiment, the secondary cooling medium takes place over the entire width of the cross-beam.

    [0099] FIG. 12 shows a modified embodiment of FIG. 11 in which there is provided a first header 410 and a second header 410 for the secondary cooling, and wherein the first header 410 supplies the central nozzle 50 with the cooling medium, and the second header 410 supplies the outer nozzles 50 with the cooling medium. In this way, the distribution of the second cooling medium can be purposefully controlled.