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    • 专利摘要:
    The invention relates to a cooling device (7) and a cooling method for secondary cooling of a strand (9) in a strand guide (5) of a continuous casting plant (1). The cooling device (7) comprises a coolant distribution system (15) with line segments (17.1 to 17.4) for conducting a coolant (19) and a plurality of coolant outlets (21) distributed via the strand guide (5) for outputting in each case a single coolant flow (Q) onto the strand ( 9), at least one switching valve (23), with which at least one Kühlmitteleinzelstrom (Q) is switched on and off, and a control unit (27), the pulse width modulation at least one Kühlmitteleinzelstroms (Q) in at least one current range (.DELTA.Q) for a time average (Q¯) of the coolant single stream (Q) by a pulse width modulated control of a switching valve (23) is formed.
    公开号:AT517772A1
    申请号:T50985/2015
    申请日:2015-11-19
    公开日:2017-04-15
    发明作者:Ing Enzinger Christian；Dipl Ing Fuernhammer Thomas；Thomas Stepanek Ing；Dipl Ing Wahl Helmut
    申请人:Primetals Technologies Austria GmbH；
    IPC主号:
    专利说明:

    description
    Secondary cooling of a strand in a continuous casting plant
    The invention relates to a cooling device and a cooling method for secondary cooling of a strand in a strand guide of a continuous casting plant.
    In continuous casting in a continuous casting plant, a metallic strand is formed in a mold and then guided in a strand guide and thereby further cooled. The cooling of the strand in the strand guide is called secondary cooling, while cooling of the strand in the mold is called primary cooling. In the secondary cooling, a coolant, for example water or a water-air mixture, is applied by means of a cooling device to the strand, as a rule.
    The invention has for its object to provide an improved cooling device and an improved cooling method for secondary cooling of a strand in a continuous casting.
    The object is achieved with respect to the cooling device by the features of claim 1 and in terms of the cooling method by the features of claim 10.
    Advantageous embodiments of the invention are the subject of the dependent claims.
    A cooling device according to the invention for the secondary cooling of a strand in a strand guide of a continuous casting plant comprises a coolant distribution system with line segments for conducting a coolant and a plurality of distributed over the strand guide coolant outlets for outputting a Kühlmitteleinzelstroms on the strand, at least one switching valve, with the at least one Kühlmitteleinzelstrom switched on and off is a control unit, which is designed for a pulse width modulation of at least one Kühlmitteleinzelstroms in a current range for a time average of the Kühlmitteleinzelstroms by a pulse width modulated driving a switching valve and a control circuit for controlling a refrigerant pressure or coolant flow in the coolant distribution system.
    The cooling device thus makes it possible to cool a strand produced in a continuous casting plant by pulse-width-modulated coolant individual streams which are output by coolant outlets distributed via a strand guide. In this case, the pulse width modulation is realized in a current range for a time average of a single coolant flow. In pulse width modulation of a single coolant flow, the coolant singletream disappears during one part of each pulse width modulation clock period and assumes a constant, non-zero current pulse value during the other part of each clock period. This current pulse value is therefore greater than the time average of the pulse width modulated coolant single stream.
    This is particularly advantageous if the time average to be set is so small that an unpulsed, d. H. temporally constant single coolant flow, which would produce this mean value, can not realize a planned beam profile of a coolant jet generated by the coolant single stream due to a too low coolant pressure. The jet profile, in particular an opening angle of the coolant jet, is in fact essential for the size of the area of the strand wetted by the coolant jet and thus for the cooling effect of the coolant jet. To produce a planned beam profile, the coolant outlets are preferably formed by corresponding outlet nozzles. The size of the coolant single stream corresponds to a coolant pressure that is insufficient to produce the intended beam profile at too small coolant single stream.
    Therefore, a pulse width modulation of a single coolant flow is preferably carried out in a current range which is limited by a threshold current at which the coolant pressure is no longer sufficient to realize an intended beam profile of a coolant jet generated by the coolant single stream. As a result of the pulse width modulation of the single coolant flow, with current pulse values that are greater than the threshold current, mean values of the coolant single stream that are smaller than the threshold current can be realized. In other words, individual coolant streams may be realized whose time averages are smaller than the threshold current and which nevertheless produce an intended beam profile of the coolant jet, since the current module values are greater than the threshold current.
    As a result of the pulse width modulation, in particular of individual coolant streams whose time averages are smaller than the threshold current, coolant jets of an intended beam profile can therefore be realized over a larger current value interval than if only unblistered coolant individual streams are used, i. H. the cooling device may operate in a larger operating window defined by this current value interval.
    Above the threshold current, unpumped single coolant streams may be generated by controlling a coolant pressure or flow in the closed-loop coolant distribution system.
    The invention also makes it possible to expand the operating window of existing conventional cooling devices in a relatively simple and cost-effective manner, ie. H. to redesign these cooling devices such that coolant jets of an intended beam profile can be realized over a larger current value interval of the coolant individual streams. All that is needed is to install switching valves and a control unit connected to the switching valves for pulse-width-modulated switching on and off of individual coolant streams, for example by replacing existing conventional line segments with line segments with switching valves and connecting the switching valves to the control unit via control lines (cost-effective compared to coolant lines), without laboriously changing or replacing the coolant distribution system as a whole. Such a transformation can also advantageously be carried out gradually, so that the operation of the continuous casting must be interrupted only for relatively short conversion times.
    As switching valves are, for example pneumatically or electrically or electromagnetically or hydraulically switchable valves. Such trained switching valves are advantageously commercially available and allow a cost-effective implementation of switched on and off coolant single streams.
    As already mentioned above, the coolant outlets are preferably each formed by an outlet nozzle. A further embodiment of this embodiment of the invention provides that at least one outlet nozzle has an exchangeable nozzle tip.
    By means of outlet nozzles formed by coolant outlets can be advantageously produced for strand cooling particularly suitable beam profiles of the output from the coolant outlets coolant jets. Exhaust nozzles with replaceable nozzle tips advantageously allow to modify these beam profiles, if necessary, in a simple manner by replacing the nozzle tips.
    Further embodiments of the invention provide that either with each switching valve exactly a single coolant flow or with at least one switching valve several Kühlmitteleinzelströme switched on and off.
    Switching valves, with each of which exactly one single coolant flow can be switched on and off, can be switched more quickly than identical switching valves for a plurality of individual coolant streams, thereby enabling a higher clock frequency of the pulse width modulation of the individual coolant streams. Furthermore, by individually controlling the switching valves, they enable more flexible control of the cooling and reduce the effects of a failure of a single switching valve. On the other hand, switching valves for a plurality of individual coolant streams advantageously reduce the number of switching valves required, and thus the costs and expense of realizing the cooling device with respect to switching valves, for a single coolant flow in each case. It therefore depends on the respective requirements of the cooling device, whether switching valves for each one or more Kühlmitteleinzelströme are more advantageous.
    Further embodiments of the invention provide at least one longitudinal row of a plurality of coolant outlets arranged one behind the other along a transport direction of the strand and / or at least one transverse row of a plurality of coolant outlets arranged side by side transversely to a transport direction of the strand.
    These embodiments advantageously permit a secondary cooling of a strand distributed uniformly over a section of a strand guide, in particular if the cooling device in each case has a plurality of longitudinal and transverse rows of coolant outlets.
    A further embodiment of the invention provides a pressure sensing device for detecting a coolant pressure in the coolant distribution system.
    Such a pressure detection device advantageously enables analysis and checking of functions of the cooling device, for example the determination of a degree of clogging of coolant outlets, by an evaluation of the signals detected by the pressure sensing device.
    In a cooling method according to the invention for secondary cooling of a strand in a strand guide of a continuous casting plant by a cooling device according to the invention, a threshold current for time averages of individual coolant streams and a current range lying below the threshold current are specified. Time averages of individual coolant streams lying in the current range are generated by setting a coolant pressure in the coolant distribution system to a constant pressure value and pulse-modulating each individual coolant flow pulse-width modulated by a switching valve having a duty cycle dependent on the average value to be generated. Out-of-flow refrigerant single-stream flows are generated by opening the switching valves of these individual coolant streams and controlling the coolant pressure or flow in the closed-loop coolant distribution system to a set point dependent on the individual coolant flows to be generated.
    With the cooling method, the above-mentioned advantageous enlargement of the operating window of the cooling device is realized in comparison to a use of unpumped single coolant flows.
    An embodiment of the cooling method provides that a plurality of individual coolant streams are pulse-width modulated in the current range for their time average values in such a way that a total coolant flow formed together by all these individual coolant streams is constant over time.
    Thus, this embodiment of the invention provides a time-delayed switching on and off of coolant individual streams in their pulse width modulation in order to keep constant a time constant of a total of coolant flow formed by all these individual coolant streams. As a result, it is advantageously possible to generate a uniform overall coolant flow output from the cooling device to the strand, even if the individual coolant flows emitted by the individual coolant outlets are each pulse width modulated.
    A further refinement of the cooling method provides that a plurality of individual coolant streams are pulse-width modulated in the current range for their time average values in such a way that a total coolant flow formed together by all these individual coolant streams is regulated to a desired value. In this case, an actual value of the total coolant flow is determined and a duty cycle and a period length of a clock period of the pulse width modulation are controlled in dependence on a deviation of the determined actual value of the desired value.
    This embodiment of the invention advantageously makes it possible to regulate a total coolant flow output from a plurality of coolant outlets to a predefinable desired value by setting the duty cycle and the period length of the pulse width modulation of the coolant individual streams. In order to determine the actual value of the total coolant flow, for example, in each case coolant pressures are detected in line segments, are output via the Kühlmitteleinzelströme, and closed by means of current-pressure characteristics on each output Kühlmitteleinzelströme. The actual value of the total coolant flow is then formed as the sum of these individual coolant streams, each multiplied by the respective duty cycle of the pulse width modulation.
    A further embodiment of the cooling method provides that a selection of coolant outlets through which coolant individual streams are output is made as a function of a width of the strand.
    As a result, the cooling of a strand can advantageously be adapted to its width. Through coolant outlets, which are not needed to cool a strand, since they are located next to the strand surface, for example, only each exhaust air in a pulse pause or a short water pulse are delivered, to prevent clogging of these coolant outlets.
    Another embodiment of the invention provides that a coolant pressure in the coolant distribution system is detected and evaluated to determine a degree of clogging of at least one coolant outlet.
    This can advantageously be a malfunction of the cooling device by a blockage of coolant outlets, which has a lack of cooling of the strand result, be recognized.
    A continuous casting plant according to the invention comprises a mold for forming a strand, a lifting device for moving the mold, a strand guide for supporting and guiding the strand and a cooling device according to the invention for secondary cooling of the strand with the advantages already mentioned above. In this case, the mold has a width adjustment for adjusting a width of the strand and the strand guide preferably has a Gießdickenverstellung for setting a thickness of the strand. As a result, strands of different widths and thicknesses can advantageously be produced. Movements of the mold, in particular oscillating movements of the mold, can advantageously be generated by the lifting device, so that the strand does not adhere to an inner surface of the mold.
    The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following description of exemplary embodiments which will be described in detail in conjunction with the drawings. 1 shows schematically a section of a continuous casting plant in a side view, FIG. 2 shows schematically a first exemplary embodiment of a cooling device for secondary cooling of a strand in a continuous casting plant in a perspective view, FIG
    4 is a perspective view of a second embodiment of a cooling device for secondary cooling of a strand in a continuous casting plant, 7 shows diagrammatically time profiles of pulse-width-modulated coolant streams which are output by a cooling device for secondary cooling of a strand in a continuous casting plant, FIG. 8 shows a duty cycle D of a pulse width modulation of a single coolant flow as a function of the mean value of the coolant single stream, and FIG 9 shows a control circuit for controlling a coolant pressure or coolant flow in a coolant distribution system.
    Corresponding parts are provided in all figures with the same reference numerals.
    FIG. 1 schematically shows a detail of a continuous casting plant 1 in a side view. Shown are a mold 3, a lifting device 4 for moving the mold 3, a mold 3 downstream strand guide 5 and a cooling device 7 of the continuous casting. 1
    The mold 3 is supplied with a metallic melt, from which a metallic strand 9 is formed with the mold 3, which is guided with the strand guide 5 and transported along a transport direction 11. With the lifting device 4 movements of the mold 4, in particular oscillating movements of the mold 4, generated so that the strand 9 does not adhere to an inner surface of the mold. The strand guide 5 has a plurality of strand guide rollers 13 for supporting the strand 9.
    The mold 3 has a width adjustment for adjusting a width of the strand 9, so that with the mold 3 strands 9 of different widths can be generated. The strand guide 5 has a Gießdickenverstellung for adjusting a thickness of the strand 9, so that with the strand guide 5 strands 9 of different thicknesses can be generated.
    The cooling device 7 serves for the secondary cooling of the strand 9 in the strand guide 5. The cooling device 7 comprises a coolant distribution system 15 with line segments 17.1 to 17.4 for conducting a coolant 19 and a plurality of coolant outlets 21 distributed over the strand guide 5 for dispensing coolant 19 onto the strand 9. Various exemplary embodiments of cooling devices 7 will be described in more detail below with reference to FIGS. 2 to 4. The coolant 19 is, for example, water.
    The continuous casting plant 1 shown in FIG. 1 is designed for so-called horizontal continuous casting, in which the strand 9 is output horizontally from the mold 3 to the strand guide 5. The invention, in particular a cooling device 7 according to the invention, however, is not limited to continuous casters 1 for horizontal continuous casting, but in particular relates to continuous casting 1, which are designed for so-called vertical continuous casting, in which the strand 9 vertically through a bottom opening of the mold 3 from the Mold 3 is output to the strand guide 5 and the strand guide 5 is carried out bent, so that the strand 9 is brought along the strand guide 5 from a horizontal to a vertical position.
    Figure 2 shows schematically a first embodiment of a cooling device 7 for the secondary cooling of a strand 9 in a continuous casting 1 in a perspective view. In this case, only a portion of the strand 9 is shown, which is located in the region of the cooling device 7. Furthermore, only one area of this section of the strand 9 and of the coolant distribution system 15 of the cooling device 7 is shown, which extends over one half of a width of the strand 9 from a lateral strand edge 9.1 of the strand 9 to a central axis 9.2 running parallel to the transport direction 11 of the strand 9 extends. Over the other half of the width of the strand 9 extends another portion of the coolant distribution system 15, which is formed as well as the area shown in Figure 2, these two areas are mirror-symmetric with respect to a mirroring on a mirror plane containing the central axis 9.2 and perpendicular to a strand surface 9.3 of the strand 9 is.
    The coolant outlets 21 of the coolant distribution system 15 form a plurality of longitudinal rows along the transport direction 11 of the strand 9 consecutively arranged coolant outlets 21. The longitudinal rows are arranged transversely to the transport direction 11 of the strand 9 side by side, so that coolant outlets 21 different longitudinal rows transverse rows transverse to the transport direction 11 juxtaposed Coolant outlets 21 form.
    In the exemplary embodiment illustrated in FIG. 2, the coolant distribution system 15 has eight longitudinal rows of coolant outlets 21 arranged side by side, wherein each longitudinal row has four coolant outlets 21. Alternative embodiments have a number of juxtaposed longitudinal rows of coolant outlets 21 and / or at least one longitudinal row with one of four different number of coolant outlets 21.
    Each coolant outlet 21 forms a strand 9 facing the end of a line end segment 17.1, which is perpendicular to the strand surface 9.3. For each longitudinal row of coolant outlets 21, the coolant distribution system 15 has a line longitudinal segment 17.2 extending parallel to the transport direction 11, which interconnects the line end segments 17.1 having these coolant outlets 21. The coolant distribution system 15 also has a transverse line segment 17.4, which runs transversely to the transport direction 11 and is connected to each line segment 17.2 via a line intermediate segment 17.3 running perpendicular to the line surface 9.3. Each line end segment 17.1 furthermore has an outlet nozzle 33 with the coolant outlet 21 for dispensing coolant 19, see FIG. 3.
    In each line end segment 17.1, a switching valve 23 is arranged, with which a coolant supply of coolant 19 to the coolant outlet 21 of this line end segment 17.1 can be interrupted. Each switching valve 23 is designed as an on / off valve, which has two operating states, wherein the switching valve 23 releases the coolant supply to the coolant outlet 21 in a first operating state and blocks the coolant supply to the coolant outlet 21 in the second operating state. A change in the operating state of a switching valve 23 is referred to herein as switching of the switching valve 23; switching from the first to the second operating state is referred to as closing the switching valve 23, and switching from the second to the first operating state is referred to as opening the switching valve 23. By each switching valve 23 so exactly one Kühlmitteleinzelstrom Q is switched on and off, which is output from a coolant outlet 21.
    The switching valves 23 are connected via control lines 25.1 to 25.4 with a control unit 27 and switchable by the control unit 27. In this case, each control line 25.1 to 25.4 connects the switching valves 23 of a longitudinal row of coolant outlets 21 to the control unit 27. The control lines 25.1 to 25.4 can run at least partially in tubes of line segments 17.1 to 17.4, cf. the description of Figure 3 below.
    The switching valves 23 are designed as pneumatically or electrically or electromagnetically or hydraulically switchable valves. Accordingly, the control lines are 25.1 to 25.4 in the case of pneumatically switchable switching valves 23 pneumatic air pressure lines, in the case of electrically or electromagnetically switchable switching valves 23 electrical lines and in the case of hydraulically switchable switching valves 23 hydraulic fluid lines.
    The control unit 27 is configured to switch the switching valves 23 in a manner described below.
    The cooling device 7 further includes a pressure detecting device 29 for detecting the refrigerant pressure P in the refrigerant distribution system 15. The signals detected by the pressure detecting device 29 are supplied to the control unit 27 via a pressure signal line 31. The control unit 27 evaluates these signals for an analysis and checking of functions of the cooling device 7, for example for determining a degree of clogging of the coolant outlets 21.
    FIG. 3 shows a perspective view of a line end segment 17.1. The line end segment 17. 1 comprises a segment tube 35, a connecting flange 37, a switching valve 23 and an outlet nozzle 33.
    The connecting flange 37 is arranged at a first end of the segment tube 35 and with a
    Longitudinal segment 17.2 connectable. At the second end of the segment tube 35, the switching valve 23 is arranged, which is formed on this end of the segment tube 35, for example by a pipe-valve screw 39, which is formed by an external thread on the outer surface of the segment tube 35 and a corresponding internal thread of the switching valve 23 can be screwed on.
    The outlet nozzle 33 has a nozzle tip 33.1 with a coolant outlet 21 and a nozzle main body 33.2. The nozzle body 33.2 is arranged on the switching valve 23 and on the switching valve 23, for example by a valve-nozzle screw 41, which is formed by an external thread on the outer surface of the switching valve 23 and a corresponding internal thread of the nozzle body 33.2, screwed. The nozzle tip 33.1 is arranged on the nozzle main body 33.2. For example, the nozzle body 33.2 has an internal thread, which corresponds to an external thread of the nozzle tip 33.1, so that the nozzle tip 33.1 can be detachably connected to the nozzle body 33.2. As a result, a jet profile of a coolant jet output by the outlet nozzle 33 can advantageously be changed by changing the nozzle tip 33.
    The segment tube 35 serves to guide coolant 19 to the coolant outlet 21 and to guide an end section of a control line 25.1 to 25.4 to the switching valve 23.
    For this purpose, the segment tube 35 has, for example, an outer tube and an inner tube running in the outer tube, wherein between the outer tube and the inner tube coolant 19 is guided and the inner tube forms the end portion of a control line 25.1 to 25.4 or surrounds. The connecting flange 37 has two flange openings 37.1, 37.2, wherein a first flange opening 37.1 serves to supply coolant 19 into the segment tube 35 and the second flange opening 37.2 serves to guide the control line 25.1 to 25.4 into the segment tube 35. The connecting flange 37 furthermore has a centering bolt 42 arranged between the flange openings 37.1, 37.2, in order to be able to mount and align the line end segment 17.1 more simply.
    FIG. 4 schematically shows a second exemplary embodiment of a cooling device 7 for secondary cooling of a strand 9 in a continuous casting plant 1 in a perspective representation analogous to FIG. The embodiment shown in Figure 4 differs from the embodiment shown in Figures 2 and 3, characterized in that not in the line end segments 17.1 each a switching valve · 23 is arranged for a coolant outlet 21, but that for each longitudinal row of coolant outlets 21 only one over a control line 25.1 to 25.4 connected to the control unit 27 switching valve 23 in one
    Intermediate segment 17.3 is arranged so that through each of these switching valves 23, a coolant supply from the line transverse segment 17.4 to a longitudinal segment segment 17.2 and all associated Leitungsendsegmenten 17.1 is interruptible. Further, in contrast to the embodiment shown in Figures 2 and 3, in each line end segment 17.1 a check valve 43 is arranged to lock a coolant supply to the line end segment 17.1 through the corresponding switching valve 23, an output of coolant 19, which is in line segments 17.1 to 17.3 between the switching valve 23 and check valve 43 is to prevent the strand 9.
    Apart from these differences, the cooling device 7 of the embodiment shown in Figure 4 is formed analogous to the embodiment shown in Figures 2 and 3. In particular, the switching valves 23 as the switching valves 23 of the embodiment shown in Figures 2 and 3 are designed as open / close valves, which are switchable by the control unit 27 in the manner described in more detail below. The line end segments 17.1 in turn each have an outlet nozzle 33, the nozzle tip 33.1 is preferably designed to be interchangeable.
    Compared to the embodiment shown in Figures 2 and 3, the embodiment shown in Figure 4 advantageously requires less switching valves 23. Compared with the embodiment shown in Figure 4, however, the embodiment shown in Figures 2 and 3 allows a higher clock frequency of the pulse width modulated circuit of the switching valves 23 (Fig. when using similar switching valves 23 in both embodiments), allows for an individual control of the switching valves 23 a more flexible control of cooling and reduces the effects of failure of a single switching valve 23, as such a failure affects a smaller surface area of the strand 9.
    FIGS. 5 to 7 illustrate a cooling method for secondary cooling of a strand 9 in a continuous casting plant 1 with a cooling device 7, which is designed like one of the exemplary embodiments illustrated in FIGS. 2 to 4.
    FIG. 5 shows a diagram for a coolant pressure P as a function of a single coolant flow Q through an outlet nozzle 33 of the cooling device 7, which is designed like one of the exemplary embodiments illustrated in FIGS. 2 and 4. In the cooling method, the individual coolant flow Q emitted by the outlet nozzle 33 through the coolant outlet 21 is switched on and off in at least one current range AQ for its time average Q by a pulse width modulated actuation of a switching valve 23 and thus itself pulse width modulated, see FIG 5, this current range AQ is limited by a threshold current Qs, which corresponds to a threshold pressure Ps. Also shown are a maximum pressure PM and a corresponding maximum flow QM, for which the outlet nozzle 33 is designed.
    The threshold current Qs is set in such a way that the coolant pressure P below the corresponding threshold pressure Ps is no longer sufficient to realize an intended beam profile of a discharged from the outlet nozzle 33 coolant jet, in particular an intended opening angle of the coolant jet to a sufficiently large area of the strand surface 9.3 with the coolant jet cover.
    Above the threshold current Qs, the individual refrigerant flows Q in the usual way, i. H. output without pulse width modulation. For this purpose, the switching valves 23 of the individual coolant streams Q to be generated are opened and the coolant pressure P or a coolant flow in the coolant distribution system 15 is regulated by means of a control loop 45 to a desired value dependent on the individual coolant flows Q to be generated, see FIG. 9.
    FIG. 6 shows a profile of a pulse-width-modulated single coolant flow Q of an outlet nozzle 33 as a function of a time t. The pulse width modulation has a clock period of the period T or a clock frequency 1 / T.
    In the illustrated example, the single refrigerant flow Q has a constant, non-zero current pulse value QP in a first half of each clock period and disappears in the second half of each clock period. Accordingly, the time average Q of the single refrigerant flow Q in this example is half the current pulse value QP.
    By means of the pulse width modulation, with a current pulse value QP that is greater than the threshold current Qs, average values Q of a coolant individual current Q that are smaller than the threshold current Qs can be realized. In other words, it is possible to realize single coolant flows Q whose time averages Q are smaller than the threshold flow Qs and which nevertheless produce an intended jet profile of a coolant jet emitted by the outlet nozzle 33.
    FIG. 7 diagrammatically shows time profiles of coolant flows Qi to Q4 and a total coolant flow Qg which are output by a cooling device 7 for secondary cooling of a strand 9 in a continuous casting plant 1 as a result of a pulse width modulated switching of the switching valves 23. In this case, the cooling device 7 is formed as one of the embodiments shown in Figures 2 or 4, wherein Figure 7 for simplicity of illustration on a cooling device 7 with only four longitudinal rows of coolant outlets 21 instead of as in the embodiments of Figures 2 and 4 eight longitudinal rows (Figure 7 may also illustrate time histories of coolant flows Qi to Q4 and total coolant flow Qg of the halves of the respective cooling devices 7 shown in Figures 2 or 4, with the other halves, not shown, being controlled analogously).
    The coolant flows Qi to Q4 are respectively output from all Kühlmittelauslässen 21 a longitudinal row and are therefore each a sum of the Kühlmitteleinzelströme Q of the coolant outlets 21 a longitudinal row, wherein the Kühlmitteleinzelströme Q are each pulse width modulated analogous to Figure 6. The total coolant flow QG is output from the coolant outlets 21 of all of these longitudinal rows together and is the sum of the coolant flows Qi to Q4.
    The switching valves 23 are switched by the control unit 27 pulse width modulated with a clock period of the period T or with a clock frequency 1 / T. In this case, the switching valves 23 for the various longitudinal rows of coolant outlets 21 are shifted in time with respect to one another, so that the total coolant flow QG is constant over time. In the example shown in FIG. 7, the switching valves 23 are switched such that a first coolant flow Qi disappears during a second half of each clock period, a second coolant flow Q2 disappears during a first and last quarter of each clock period, a third coolant flow Q3 during the first half of each Clock period disappears, a fourth coolant flow Q4 during a second and third quarter of each clock period disappears and the coolant flows Qi to Q4 in the remaining times take a constant, for all longitudinal rows same, non-zero value, which is half the total coolant flow QG.
    The total coolant flow QG is regulated in the pulse width modulation to a predetermined setpoint. For this purpose, an actual value of the total coolant flow QG is determined, and a duty cycle D and the period length T of the pulse width modulation are regulated as a function of a deviation of the determined actual value from the desired value. As usual, the duty cycle D of the pulse width modulation is understood to be the ratio of a pulse duration during a clock period to the period length T. In the examples shown in FIGS. 6 and 7, the duty cycle D is 50%, for example. In order to determine the actual value of the total coolant flow QG, for example, in each case coolant pressures P in line segments 17.1 to 17.4, via which individual coolant streams Q are output, are detected and closed therefrom by means of current-pressure curves for the individual coolant flows Q output.
    The actual value of the total coolant flow QG is then formed as the sum of these individual coolant flows Q, in each case multiplied by the respective duty cycle D of the pulse width modulation.
    FIG. 8 shows the duty cycle D of the pulse width modulation of a coolant single-flow Q as a function of the average value Q of the coolant single-flow Q in the current range AQ. Time average values Q of the coolant individual flows Q lying in the current range AQ are produced by setting the coolant pressure P in the coolant distribution system 15 to a constant pressure value which is at least as great as the threshold pressure Ps and each individual coolant flow Q by a pulse width modulated actuation of a switching valve 23 is pulse width modulated with a duty cycle D dependent on the mean value Q to be generated. The duty cycle D therefore increases within the current range AQ with increasing average value Q up to a duty cycle Dm. For example, in the case where the refrigerant pressure P in the refrigerant distribution system 15 is set to the threshold pressure Ps, the duty degree end value Dm becomes 1. When the refrigerant pressure P in the refrigerant distribution system 15 is set to a larger pressure value, the duty degree Dm is correspondingly smaller.
    Further, in the cooling method, a selection of coolant outlets 21 through which refrigerant single streams Q are output is made depending on a width of the string 9. In this case, are discharged through coolant outlets 21, which are not needed to cool the strand 9, since they are located next to the strand surface 9.3, for example, only each exhaust air in a pulse pause or a short water pulse to prevent clogging of these coolant outlets 21.
    FIG. 9 shows a control circuit 45 for controlling a refrigerant pressure P or refrigerant flow in the refrigerant distribution system 15 to produce individual refrigerant flows Q that are greater than the threshold flow Qs. The control variable R of the control loop 45 is therefore the coolant pressure P or coolant flow in the coolant distribution system 15. A reference variable S of the control loop 45 is accordingly a desired value of the coolant pressure P or coolant flow in the coolant distribution system 15 depending on the coolant individual flows Q. The control loop 45 comprises a regulator 47 The regulator 47 is a pump for directly producing a refrigerant pressure P or refrigerant flow in the coolant distribution system 15, or a pump having a downstream pressure or flow regulator for reducing a refrigerant pressure P or coolant flow generated by the pump in the coolant distribution system 15. The controlled system 49 is the coolant distribution system 15. The measuring member 51 is a pressure detecting device 29 for detecting the refrigerant pressure P or a current detecting device for detecting a refrigerant flow ms in the coolant distribution system 15. To control the controlled variable R, a control deviation E of the controlled variable R is formed by the reference variable S. The controller 47 generates a control variable U dependent on the control deviation E in order to reduce the control deviation B.
    While the invention has been further illustrated and described in detail by way of preferred embodiments, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.
    REFERENCE LIST I continuous casting machine 3 mold 4 lifting device 9 strand axis 9.2 central axis 9.3 strand surface II transport direction 13 strand guide roll 15 coolant distribution system 17.1 line end segment 17.2 longitudinal pipe segment 17.3 intermediate line segment 17.4 line cross segment 19 coolant 21 coolant outlet 23 switching valve 25.1 to 25.4 control line 27 control unit 29 pressure sensing device 31 pressure signal line 33 Outlet nozzle 33.1 Nozzle tip 33.2 Nozzle body 35 Segment tube 37 Connecting flange 37.1, 37.2 Flange opening 39 Valve screw connection 41 Valve and nozzle screw connection 42 Centering pin 43 Check valve 45 Control loop 47 Regulator 49 Control path 51 Measuring element D Duty cycle
    Dm Duty cycle value E Control deviation P Coolant pressure
    Ps Threshold pressure PM Maximum pressure R Control value Q Single coolant flow QP Current pulse value
    Qi to Q4 coolant flow Qg total coolant flow
    Qs threshold current
    Qm Maximalström AQ current range Q mean value S reference variable t time T period length U manipulated variable
    权利要求:
    Claims (15)
    [1]
    claims
    1. Cooling device (7) for secondary cooling of a strand (9) in a strand guide (5) of a continuous casting plant (1), the cooling device (7) comprising - a coolant distribution system (15) with line segments (17.1 to 17.4) for conducting a coolant (19 ) and a plurality of distributed over the strand guide (5) coolant outlets (21) for outputting a Kühlmitteleinzelstroms (Q) on the strand (9), - at least one switching valve (23), with the at least one Kühlmitteleinzelstrom (Q) on and off , - a control unit (27), which is formed for a pulse width modulation of at least one Kühlmitteleinzelstroms (Q) in a current range (AQ) for a time average (Q) of the Kühlmitteleinzelstroms (Q) by a pulse width modulated control of a switching valve (23) - and one Control circuit (45) for controlling a refrigerant pressure (P) or coolant flow in the coolant distribution system (15).
    [2]
    Second cooling device (7) according to claim 1, characterized by at least one pneumatically or electrically or electromagnetically or hydraulically switchable switching valve (23).
    [3]
    3. Cooling device (7) according to one of the preceding claims, characterized by at least one of an outlet nozzle (33) formed coolant outlet (21).
    [4]
    4. cooling device (7) according to claim 3, characterized in that at least one outlet nozzle (33) has an exchangeable nozzle tip (33.1).
    [5]
    5. Cooling device (7) according to one of the preceding claims, characterized in that with each switching valve (23) exactly one coolant single stream (Q) is switched on and off.
    [6]
    6. cooling device (7) according to one of claims 1 to 4, characterized in that with at least one switching valve (23) a plurality of Kühlmitteleinzelströme (Q) switched on and off.
    [7]
    7. Cooling device (7) according to one of the preceding claims, characterized by at least one longitudinal row of a plurality of along a transport direction (11) of the strand (9) successively arranged coolant outlets (21).
    [8]
    8. Cooling device (7) according to any one of the preceding claims, characterized by at least one transverse row of a plurality of transverse to a transport direction (11) of the strand (9) juxtaposed coolant outlets (21).
    [9]
    9. cooling device (7) according to any one of the preceding claims, characterized by a pressure detecting device (29) for detecting a refrigerant pressure (P) in the coolant distribution system (15).
    [10]
    10. A cooling method for secondary cooling of a strand (9) in a strand guide (5) of a continuous casting plant (1) by a cooling device (7) according to one of the preceding claims, wherein - a threshold current (Qs) for time averages (Q) of individual coolant streams (Q ) and a current range (AQ) lying below the threshold current (Qs), - time average values (Q) of coolant individual currents (Q) lying in the current range (AQ) are generated by a coolant pressure (P) in the coolant distribution system (15) is set to a constant pressure value and each individual coolant flow (Q) is pulse-width modulated by a pulse width modulated control of a switching valve (23) with a duty cycle (D) dependent on the average value (Q) to be generated, and individual coolant flows outside the current range (AQ) ( Q) are generated by the switching valves (23) of these Kühlmitteleinzelströme (Q) are opened and the coolant pressure (P) or a coolant flow in the coolant distribution system (15) is regulated by the control circuit (45) to a desired value dependent on the coolant single streams (Q) to be generated.
    [11]
    11. Cooling method according to claim 10, characterized in that a plurality of individual coolant streams (Q) are pulse-width modulated in the current range (AQ) for their time average values (Q) in such a way that a total coolant flow (QG) formed together by all these individual coolant streams (Q) is constant over time is.
    [12]
    12. A cooling method according to claim 10 or 11, characterized in that a plurality of individual coolant streams (Q) are pulse-width modulated in the current range (AQ) for their time average values (Q) in such a way that a total coolant flow (QG) formed together by all these individual coolant streams (Q) is controlled to a desired value, wherein an actual value of the total coolant flow (QG) is determined and a duty cycle (D) and a period length (T) of a clock period of the pulse width modulation in response to a deviation of the determined actual value are controlled by the desired value.
    [13]
    A cooling method according to any one of claims 10 to 12, characterized in that a selection of refrigerant outlets (21) through which refrigerant single streams (Q) are dispensed is made in response to a width of the strand (9).
    [14]
    14. Cooling method according to one of claims 10 to 13, characterized in that a coolant pressure (P) in the coolant distribution system (15) detected and evaluated to determine a degree of clogging of at least one coolant outlet (21).
    [15]
    15. Continuous casting plant (1), comprising - a mold (3) for forming a strand (9), - a lifting device (4) for moving the mold (3), - a strand guide (5) for supporting and guiding the strand (9 ) - And a cooling device (7) according to one of claims 1 to 9, - wherein the mold (3) has a width adjustment for adjusting a width of the strand (9).
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    同族专利:
    公开号 | 公开日
    EP3347151B1|2021-05-19|
    EP3417959A1|2018-12-26|
    AT517772B1|2018-12-15|
    EP3417959B1|2021-05-26|
    EP3347151A1|2018-07-18|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    WO2007121804A1|2006-04-25|2007-11-01|Siemens Vai Metals Technologies Gmbh & Co|Spray-nozzle adjusting device|
    WO2011144266A1|2010-05-19|2011-11-24|Sms Siemag Ag|Strand guiding device|
    EP2527061A1|2011-05-27|2012-11-28|Siemens VAI Metals Technologies GmbH|Method for cooling a metallic strand and switching valve for intermittent opening and closing of a volume flow of a coolant medium|AT520006A1|2017-06-07|2018-12-15|Primetals Technologies Austria GmbH|COOLANT NOZZLE FOR COOLING A METALLIC STRING IN A CONTINUOUS CASTING SYSTEM|AT409940B|2001-02-20|2002-12-27|Voest Alpine Ind Anlagen|TWO-MATERIAL SHAFT NOZZLE AND CONTINUOUS CASTING SYSTEM WITH AN ARRANGEMENT OF TWO-FABRIC SHAFT NOZZLES|
    DE202011110064U1|2011-06-07|2012-11-16|Sms Siemag Ag|Nozzle device and strand guiding device with the nozzle device|
    法律状态:
    优先权:
    申请号 | 申请日 | 专利标题
    AT507672015|2015-09-07|PCT/EP2016/070441| WO2017042059A1|2015-09-07|2016-08-31|Secondary cooling of a strand in a strand casting system|
    EP18179585.7A| EP3417959B1|2015-09-07|2016-08-31|Secondary cooling of a strand in a strand casting assembly|
    EP16757916.8A| EP3347151B1|2015-09-07|2016-08-31|Secondary cooling of a strand in a strand casting system|
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