JP2008168308A - Method and apparatus for controlling flow rate of secondary cooling water in continuous casting machine, continuous casting method, and equipment therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable a continuous casting machine to stably continue a casting operation even when a controller is troubled and to produce a high-quality slab. <P>SOLUTION: When the flow rate of secondary cooling water in a continuous casting machine is controlled, the setting of a parameter for flow rate calculation (calculator 40) and the calculation of flow rate control (instrumentation controller 48) are performed by independent devices, thus casting can be stably continued even in case of device abnormality. The holding of one or more parameters for flow rate control, and the joint tracking and width change tracking of a slab can be performed within the instrumentation controller 48 performing the calculation of flow rate control. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a secondary cooling water flow rate control method, apparatus, continuous casting method, and equipment for a continuous casting machine. In a continuous casting machine, the casting can be stably continued even when the control device fails, and the quality can be improved. The present invention relates to a secondary cooling water flow rate control method and apparatus for a continuous casting machine capable of producing a good slab, and a continuous casting method and equipment using them.

  In FIG. 1, the image figure of an example of a continuous casting machine is shown. In the figure, 10 is a casting pan containing molten steel 8, 14 is a tundish into which molten steel 8 is injected via an air seal pipe (ASP) 12, and 20 is molten steel 8 injected through an immersion nozzle 16. A mold for primary cooling to make a slab 22, a spray nozzle 24 for spraying cooling water or the like below the mold 20 to perform secondary cooling, and a mold 26 for cooling the slab 22 after secondary cooling. A pinch roll 28 for pulling out is a dummy bar receiver for removing a dummy bar (not shown) attached to the tip of the slab 22 at the start of casting from the slab 22 and receiving it, 30 is a front table under the cutter, and 32 is a casting It is a cutter for cutting the piece 22 by a predetermined length.

  In order to perform stable production with such a continuous casting machine, the stability of the oscillation function such as mold vibration and the molten steel cooling function such as primary and secondary cooling becomes a problem. If these devices become abnormal for some reason, there is a possibility of causing product quality problems and equipment destruction, and casting must be stopped. Secondary cooling is cooling by spraying cooling water or the like directly from the spray nozzle 24 to the slab 22 in order to further cool the slab 22 and promote solidification after the primary cooling is performed by the mold 20. This is a very important control function for performing final cooling to change the molten steel 8 from liquid to solid. In the secondary cooling, in order to improve the cooling performance, mist air cooling in which air is atomized and mixed with water may be performed.

  FIG. 2 shows an image diagram of an example of a conventional secondary cooling water control system. This control system includes a computer 40, a loop controller 42, and a flow rate adjustment valve 44. The 1-loop controller 42 is installed corresponding to each flow control valve 44. The computer 40 takes in the casting speed from the electric controller 46 and calculates the flow rate setting value of the secondary cooling water by an arithmetic expression constituted by the casting speed and the parameters.

  The flow rate set value calculated inside the computer 40 is set by the computer 40 to the one-loop controller 42, and control is performed so that the flow rate set value transmitted from the computer 40 becomes the feedback control by the one-loop controller 42. ing.

  FIG. 3 shows a system configuration in which a large-scale instrumentation controller (hereinafter referred to as DCS) 48 called DCS (Distributed Control System) instead of the one-loop controller 42 is incorporated as a flow control device. In this system, the feedback control performed by the one-loop controller 42 in FIG. 2 is performed by the DCS 48 so that the flow rate set value transmitted from the computer 40 is obtained.

JP-A-57-206559

  In these system configurations, parameters for calculating the flow rate set value are held in the computer 40, and the computer 40 calculates the flow rate set value every time the casting speed changes, and the flow rate is set in the one-loop controller 42 or the DCS 48. It was necessary to transmit a value.

  Therefore, when the computer 40 fails, the flow rate set value cannot be calculated and transmitted, and casting is stopped.

  As described above, if the device for performing the parameter selection for calculating the flow rate setting value of the secondary cooling water and the device for performing the actual flow rate setting are the same device, the failure, the parameter selection cannot be performed, and the flow rate setting cannot be performed. It becomes a problem that must be canceled, which is a problem. The set value of the command flow rate can be calculated and set by manual operation of the operator, but the command flow rate is determined by the casting speed, so the command flow rate can be calculated accurately or by changing the casting speed. It is difficult to change the set value from time to time, and there is a problem in quality in a slab that is not cooled at such an appropriate set value flow rate.

  As in the present invention, Patent Document 1 relating to the flow rate control of the secondary cooling water of the continuous casting facility discloses a technique of how to efficiently increase the cooling efficiency and stably supply the cooling water. There was no disclosure about the stable casting technique when the apparatus for calculating and setting the flow rate set value is abnormal.

  The present invention has been made to solve the above-mentioned conventional problems, and even when the control system for the secondary cooling water is abnormal, it is possible to appropriately set the secondary cooling water in consideration of changes in the casting speed. The objective is to continue stable casting as much as possible.

  In the present invention, when controlling the flow rate of the secondary cooling water in the continuous casting machine, the setting of the flow rate calculation parameter and the calculation of the flow rate control are performed by an independent device, so that casting can be continued stably even when the device is abnormal. Thus, the above-described problem is solved.

  One or more parameters for flow rate calculation can be held in the instrumentation controller that performs the flow rate control calculation.

  In addition, slab seam tracking and width change tracking can be performed in the instrumentation controller that performs the flow rate control calculation.

  The present invention also provides a continuous casting method characterized in that the flow rate of the secondary cooling water is controlled by the above control method.

  Further, in the secondary cooling water flow rate control device for a continuous casting machine, the above-mentioned problem is solved by providing means for setting flow rate calculation parameters and flow rate control calculation means independent of the flow rate calculation parameter setting means. It is a thing.

  The present invention also provides a continuous casting facility including the secondary cooling water flow rate control device.

  In the present invention, since the control setting method of the secondary cooling water is shared between, for example, a computer and an instrumentation controller (for example, DCS), and the function is constructed, the change in the casting speed is taken into account even when the system is abnormal. Appropriate flow rate calculation can be performed, and stable casting and continuous production of high quality materials are possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  The system configuration of the present embodiment is the same as that in FIG. 3, but the control device that performs the flow rate setting value calculation of the secondary cooling water is changed. That is, in the conventional system shown in FIGS. 2 and 3, a parameter for calculating the flow rate set value is held in the computer 40, and the set value is calculated using the parameter, and is used as the one-loop controller 42 (FIG. 2) or DCS48 (FIG. 3).

  On the other hand, in the system of the present embodiment shown in FIG. 4, the flow rate setting value for calculating the flow rate setting value is not transmitted from the computer 40 to the DCS 48 but the flow rate setting value is calculated. In the DCS 48, the flow rate calculation parameters are held and used to directly calculate the flow rate set value. Therefore, it is necessary to take in the casting speed into the DCS 48 and take in from the electric controller 46.

  The flow rate calculation parameter is transmitted from the computer 40 to the DCS 48 and held, for example, at the timing when casting is started. In the case of continuous casting in which many casting pans are continuously cast, the flow rate calculation parameters described above are set when the casting of the previous casting pan is completed and the next casting pan is set at the casting position. I try to transmit.

  Here, the flow rate calculation parameter transmitted from the computer 40 to the DCS 48 includes, for example, “initial casting”, as illustrated in a conceptual diagram of a secondary cooling water pattern (referred to as a secondary cooling pattern) illustrated in FIG. There are six modes of “steady casting”, “head tightening”, “redrawing”, “accident”, and “spray change”, and these are considered as patterns for one casting pan. In addition, since the width of the slab to be cast is differentiated between wide and narrow, the two types of patterns, one for wide and one for narrow, are considered as a group for each casting pan, and the computer starts at the timing of casting. 40 to DCS 48.

  In the case of casting only one casting pan, there is only one steel type in the continuous casting machine, but in the case of continuous casting, as shown in the image diagram of FIG. There may be multiple seams between the casting pan and the casting pan. Since the pattern of the secondary cooling water from the spray nozzle 24 is different for each casting pan, it is necessary to transmit the pattern from the computer 40 to the DCS 48 each time. In order to perform continuous casting, the DCS 48 maintains several types of secondary cooling patterns, judges the joint between the casting pan and the casting pan, and tracks the state in which the joint advances through the continuous casting machine. The cooling water is controlled while monitoring. In the figure, 50 is a width change device and 52 is a common control LAN.

  The joint can be detected by the following method, for example. It is assumed that the continuous casting is performed by the casting pan 10A and the casting pan 10B. FIG. 7 shows an image diagram. Casting is started ((A) in the figure), and after all of the molten steel 8A in the pouring pan 10A is poured into the mold 20 ((C) in the figure) after the state of (B) in the figure, casting is performed. It is changed from the pan 10A to the pouring pan 10B ((D) in the figure), and the weight (molten steel amount) of the molten steel 8A remaining in the tundish 14 at the timing when the molten steel 8B in the pouring pan 10B starts to be poured. Remember. This weight decreases as casting progresses, and the timing at which it becomes 0 tons is used as a joint ((E) in the figure). The amount of decrease is the product of mold thickness, mold width, molten steel density, and casting speed.

  Then, the casting length of the seam point is stored, and the location of the seam in the continuous casting machine is tracked. FIG. 8 shows a signal processing path for seam tracking.

  On the other hand, width change tracking is performed by the following method. FIG. 9 shows a signal processing path for width change tracking. The width value of the mold 20 is on the common control LAN 52, and the DCS 48 constantly monitors it. Since the width change completion signal is output from the width change device 50 at the timing when the width change is completed during casting, the width value and the casting length at that time are stored. From the stored casting length, it is possible to track which part in the continuous casting machine has the width change point and what the width value is. As a result, the width and width of the secondary cooling are switched.

  In the above embodiment, the control command is directly output from the DCS 48 to the flow rate adjustment valve 44. However, the control command may be output to the one-loop controller 42. An instrumentation controller other than DCS 48 can also be used.

Overall configuration diagram of an example of a continuous casting machine Block diagram showing an example of a conventional secondary cooling water setting method A block diagram showing another example of the same method The block diagram which shows the principal part structure of embodiment of this invention The conceptual diagram which shows the example of the secondary cooling pattern used by the said embodiment Overall configuration diagram of the embodiment Sectional drawing explaining the joint detection method of the continuous casting used in the said embodiment A configuration diagram for explaining the seam tracking method of the slab. Configuration diagram for explaining the width change tracking method

Explanation of symbols

8 ... Molten steel 10, 10A, 10B ... Casting pan 14 ... Tundish 16 ... Immersion nozzle 20 ... Mold 22 ... Slab 24 ... Spray nozzle 26 ... Pinch roll 40 ... Calculator 42 ... 1 loop controller 44 ... Flow control valve 46 ... Electric controller 48 ... Large-scale instrumentation controller (DCS)
50 ... width change device 52 ... common control LAN

Claims (6)

When controlling the flow rate of secondary cooling water in a continuous casting machine,
Secondary cooling of a continuous casting machine characterized in that the setting of flow rate calculation parameters and the calculation of flow rate control are performed by an independent device so that casting can be stably continued even when the device is abnormal. Water flow control method.   The secondary cooling water flow rate control method for a continuous casting machine according to claim 1, wherein one or more types of flow rate calculation parameters are held in an instrumentation controller that performs the flow rate control calculation.   The secondary cooling water flow rate control method for a continuous casting machine according to claim 1, wherein slab seam tracking or width change tracking is performed in an instrumentation controller for calculating the flow rate control.   A continuous casting method, wherein the flow rate of the secondary cooling water is controlled by the control method according to claim 1. Means for setting parameters for flow rate calculation;
Flow control calculation means independent of the flow rate parameter setting means;
A secondary cooling water flow rate control device for a continuous casting machine, comprising:   A continuous casting facility comprising the secondary coolant flow rate control device according to claim 5.

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