JP4894686B2 - Manufacturing method and manufacturing apparatus for hot-rolled steel sheet - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method and an apparatus for manufacturing a hot-rolled steel sheet, specifically, a hot-rolled steel sheet including a hot rolling mill, a water cooling device, a winder, and a control controller that controls the water cooling device. The present invention relates to an apparatus and a manufacturing method.

FIG. 8 is an explanatory view schematically showing an example of a hot-rolled steel sheet manufacturing apparatus 0.
As is well known, in manufacturing a hot-rolled steel sheet, a hot steel sheet 1 that has been hot-rolled by a finishing mill 2 at a finishing temperature of about 900 ° C. is transported by a transport table 3. Then, cooling water is sprayed onto the steel sheet 1 by the water cooling device 5 installed on the transfer table 3 to cool it to a predetermined winding temperature, and then wound around the coil by the winding device 4. Since the mechanical properties of the hot-rolled steel sheet are governed by the coiling temperature, in order to produce a hot-rolled steel sheet having the desired mechanical properties, the coiling temperature is controlled by controlling the coiling temperature, that is, by using the water-cooling device 5. It is extremely important to improve the control accuracy. This water cooling device 5 has a plurality of (n in the illustrated example) water amount adjustment valves arranged in parallel in the conveying direction of the steel plate 1, the opening degree of which can be controlled independently, toward the steel plate 1. Adjust the amount of cooling water to be injected.

  Reference numeral 6 in FIG. 8 indicates a finishing outlet thermometer for measuring the temperature of the steel sheet 1 at the exit of the finishing mill 2, reference numeral 7 indicates a winding thermometer for measuring the winding temperature, and reference numeral 9 indicates A steel plate thickness measuring device is shown. Reference numeral 10 denotes a steel plate speed measuring device. Reference numeral 11 denotes a steel plate temperature predicting device. Reference numeral 12 denotes a cooling control device for controlling the opening of each water amount adjusting valve. In the following description, the steel plate temperature prediction device 11 and the cooling control device 12 are collectively referred to as a controller 13.

  When the steel plate 1 rolled by the finishing mill 2 passes through the finishing outlet thermometer 6, the surface temperature and the plate thickness of the steel plate 1 are measured at a predetermined cycle, and a sampling point is set on the steel plate 1. The steel plate temperature prediction device 11 is based on the sampling point temperature, the plate thickness and the passing speed when passing through the water cooling device 5, the specific heat of the steel plate 1, the density, the water amount of the water cooling device 5, the water temperature and the air temperature. Predicts the temperature of the steel sheet 1 when it reaches the winding thermometer 7 by calculation.

  When the predicted value of the coiling temperature of the steel sheet 1 does not match the target value, the cooling control device 12 opens each water amount adjustment valve of the water cooling device 5 so that the predicted value of the coiling temperature matches the target value. Change and set the degree. In addition, when the measured value of the coiling temperature by the coiling thermometer 7 does not match the target value, the cooling control device 12 performs feedback control so that the predicted value of the coiling temperature matches the target value, The opening degree of each water amount adjustment valve of the water cooling device 5 is changed and set.

  The steel plate 1 is on the transfer table 3 for the above processing, that is, (a) measurement by the finishing outlet thermometer 6, (b) prediction of the coiling temperature, and (c) change setting of the water amount adjustment valve of the water cooling device 5. The temperature of the steel sheet 1 that has been cooled by passing through the transfer table 3 is changed by sequentially setting and changing the water amount adjusting valve of the water cooling device 5 in this cycle. When it reaches the winding thermometer 7 on the inlet side, control is performed so as to match the target value of the winding temperature.

  This control method controls the predicted value of the coiling temperature of the steel plate 1 to a target value. For this reason, in order to increase the control accuracy of the coiling temperature, it is indispensable to perform a predictive calculation of the temperature of the steel sheet 1 from the finishing mill 2 to the coiling device 4 with high accuracy. Not only the amount of heat deprived from the steel plate 1 by water cooling and the amount of heat deprived from the steel plate 1 by air cooling, but also the amount of heat generated in the steel plate 1 by the phase transformation accompanying water cooling must be accurately predicted. However, it is extremely difficult to accurately predict all these heat quantities.

  Therefore, as shown in FIG. 9, a plurality (three in the illustrated example) of water cooling devices 5a to 5c are provided in the conveying direction of the steel plate 1, and the surface temperature of the steel plate 1 is measured between the water cooling devices 5a to 5c. By installing the intermediate thermometers 8b and 8c that can be performed, that is, by dividing the water cooling device 5 shown in FIG. 8 into three toward the conveying direction of the steel sheet 1, it corresponds to each of the water cooling devices 5a to 5c. An invention is disclosed in which the control accuracy of the prediction calculation of the temperature of the steel sheet 1 is improved by shortening the cooling control section handled by the control controllers 13a to 13c and thereby reducing the temperature prediction error in one cooling control section. Yes.

  For example, in Patent Document 1, an individual target temperature is set for each of a plurality of water cooling devices, and each of the plurality of water cooling devices is individually controlled according to the difference between the temperature detected by the temperature detection means and the target temperature. Thus, an invention for improving the control accuracy of the winding temperature is disclosed.

  In addition, in Patent Document 2, similarly to the invention disclosed in Patent Document 1, a plurality of water cooling devices and temperature detecting means are provided, and the temperature distribution of the steel sheet during the cooling is estimated and calculated to calculate the coiling temperature. An invention for improving control accuracy is disclosed.

According to the inventions disclosed in Patent Documents 1 and 2, when the hot rolling conditions such as the passing speed of the steel plate during hot rolling are constant without being changed, the winding of the steel plate with sufficiently high control accuracy is possible. It is possible to control the taking temperature.
JP-A-7-185632 Japanese Patent Publication No. 5-25567

  However, in the actual production of hot-rolled steel sheets, the steel sheets used in hot rolling are subject to operational fluctuations in the hot rolling process and application of accelerated rolling (a technology that accelerates the steel sheet speed during rolling and suppresses temperature drop). In most cases, the passing speed (rolling speed) is changed from the set value of the rolling speed.

Moreover, in actual manufacture of a hot-rolled steel plate, the temperature and thickness of the steel plate on the exit side of the finish rolling mill may deviate from the set values for some reason.
The rolling speed and the temperature and thickness of the steel plate on the exit side of the finish rolling mill are both set in advance as hot rolling conditions, and cooling by each water cooling device is also determined based on this setting value. . For this reason, when the hot rolling conditions are changed, the cooling conditions of the water cooling apparatus must be set again.

  Here, in order to implement the invention disclosed in Patent Document 1, it is necessary to set individual target temperatures for each of the plurality of water cooling devices. For this reason, as described above, when the hot rolling conditions such as the rolling speed are changed during the hot rolling, the individual target value for each water cooling device is set within the range of the facility capacity of each water cooling device. Thus, all the water cooling devices must be individually and quickly corrected and set. However, Patent Document 1 does not disclose any means for correcting and setting all target temperatures of each water cooling device in this way. For this reason, the invention disclosed in Patent Document 1 cannot sufficiently cope with the case where the hot rolling conditions such as the rolling speed are changed during the hot rolling, and the winding temperature is set to the target temperature. It may not be possible to control.

  FIG. 10 is a graph showing an example of the temperature of the steel sheet cooled by the water cooling device over time. As shown by thin lines in the graph of FIG. 10, even in the invention disclosed by Patent Document 1, if the rolling speed during hot rolling is not changed during hot rolling, all the water cooling devices The coiling temperature of the steel sheet can be accurately controlled to the target temperature by properly exhibiting the cooling capacity. However, for example, when the rolling speed is changed to a higher speed during hot rolling, as shown by the thick line in the graph of FIG. ), After this change, the target coiling temperature can be obtained even if the cooling conditions of each subsequent water cooling device are modified and set to the maximum equipment capacity. Disappear.

  Further, in the invention disclosed in Patent Document 2, only the method of setting the water cooling device after the temperature detecting means is described, so that the cooling capacity of the entire water cooling device is effective when the rolling speed is changed during the hot rolling. However, it is impossible to improve the control accuracy of the coiling temperature.

  Thus, even if it is going to control the coiling temperature of a steel plate to a target temperature with high control accuracy using a plurality of water cooling devices and a thermometer installed between each water cooling device, in the conventional invention, the rolling speed, etc. If the hot rolling conditions are changed during the hot rolling, it is difficult to correct and set the target temperature of all the water cooling devices appropriately and quickly, and the coiling temperature of the steel sheet is controlled to the target temperature. It may not be possible.

  The present invention has been made in view of such problems of the prior art, and the hot rolling conditions such as the rolling speed and further the temperature or thickness of the steel sheet at the exit side of the finish rolling mill are hot rolled. Even when performing rolling operations that are changed during the process, all target temperatures of each water cooling device can be corrected and set appropriately and quickly, thereby setting the coiling temperature of the steel sheet to the target temperature. An object of the present invention is to provide a method and apparatus for producing a hot-rolled steel sheet that can be accurately controlled.

  As shown in FIG. 9, in the conventional technique using the intermediate thermometers 8b and 8c, the cooling control section controlled by one controller 13a, 13b or 13c and one water cooling device 5a, 5b or 5c are one to one. For example, the controller 13a does not control the water cooling devices 5b and 5c. For this reason, in the prior art, in order to effectively utilize the cooling capacity of all the water cooling devices 5a to 5c, it is necessary to set an appropriate target temperature for each of the water cooling devices 5a to 5c, which is difficult. Met.

  On the other hand, in the present invention, as illustrated in FIG. 2 described later, at least one controller 13a is installed in a section from the thermometer 6 installed on the inlet side of the water cooling device 5a to the winding thermometer 7. In other words, in order to effectively use the cooling capacities of all the water cooling devices 5a to 5c corresponding to all the water cooling devices 5a to 5c, it is possible to control all the water cooling devices 5a to 5c. The controller 13a and the second controller that improves the control accuracy of the coiling temperature by correcting the set values of the water amount adjusting valves of the water cooling devices 5a to 5c set by the first controller 13a. 13b or the third controller 13c, both of the water cooling devices 5a to 5c can be cooled without setting an appropriate target temperature for each of the water cooling devices 5a to 5c. It is based on the finding that can be effectively utilized capacity.

The present invention is preliminarily determined from each of a plurality of water-cooling apparatuses arranged in parallel in the steel sheet transport direction toward the steel sheet transported by the transport table after being hot-rolled by a hot rolling mill. After cooling the steel sheet by injecting cooling water under a predetermined cooling condition by predicting the coiling temperature of the steel sheet by calculation based on the hot rolling conditions, the coil is wound around a coil by a winder and hot rolled. When manufacturing a steel sheet, when changing to another hot rolling condition different from the predetermined hot rolling condition in the course of hot rolling and continuing the hot rolling, other hot rolling conditions And a plurality of water cooling devices capable of setting the coiling temperature of the steel sheet as a target value based on the measured value of the temperature of the steel sheet on the inlet side of the water cooling apparatus located on the most upstream side of the plurality of water cooling apparatuses. Set value of cooling condition for all devices Further, based on other hot rolling conditions and the measured value of the temperature of the steel sheet on the inlet side of one or more water cooling devices other than the water cooling device located on the most upstream side among the plurality of water cooling devices. Further, the setting value of the cooling condition obtained for at least one or two or more water cooling devices is further corrected and set , and the water cooling device can control the opening degree independently and the cooling water to be injected. A method for producing a hot-rolled steel sheet , comprising: a plurality of water amount adjusting valves for adjusting the amount of water, wherein the cooling condition is an opening degree of the water amount adjusting valve .

From another viewpoint, the present invention is conveyed by a hot rolling mill for hot rolling of a steel sheet, a conveying table for conveying a steel sheet hot-rolled by a hot rolling mill, and a conveying table. A winding device that winds a steel plate around a coil, and a plurality of steel plates arranged in parallel in the conveying direction of the steel plate, and a steel plate based on predetermined hot rolling conditions toward the steel plate conveyed by the conveying table The temperature of the steel sheet at the entry side of each of the plurality of water cooling devices is measured by injecting the cooling water under a predetermined cooling condition by predicting the winding temperature of the steel sheet by calculation. In addition, a thermometer that measures the temperature of the steel plate on the outlet side of the water cooling device located at the most downstream of the plurality of water cooling devices, and further calculates the coiling temperature of the steel plate cooled by the plurality of water cooling devices A hot-rolled steel sheet manufacturing apparatus comprising a controller for controlling a coiling temperature to a target temperature by controlling a plurality of the water cooling devices based on a more predicted result, wherein the controller is hot In the middle of rolling, when changing to another hot rolling condition different from the predetermined hot rolling condition and continuing the hot rolling, the other hot rolling conditions and a plurality of water cooling devices Based on the measured value of the temperature of the steel sheet on the inlet side of the water cooling device located on the most upstream side of the water, the setting of the cooling conditions in all the plurality of water cooling devices that can set the coiling temperature of the steel sheet as a target value The value is obtained, and further, the other hot rolling conditions and the measured value of the temperature of the steel sheet on the inlet side of one or more water cooling devices other than the water cooling device located on the most upstream side among the plurality of water cooling devices. Based on at least 1 or 2 The set value of the cooling conditions determined for water-cooling unit of the above, be set by further modifications, and water-cooling device, a plurality of adjusting the quantity of cooling water to be injected be controllable opening independently The apparatus for producing a hot-rolled steel sheet has a water amount adjusting valve, and the cooling condition is an opening degree of the water amount adjusting valve .

In these present inventions, the hot rolling conditions are exemplified by the rolling speed of hot rolling or the temperature or thickness of the steel plate on the exit side of the finishing mill of the hot rolling mills .

  In order to implement the present invention described above, a thermometer is installed on the inlet side of one or more water cooling devices other than the water cooling device located on the most upstream side among the plurality of water cooling devices. However, in an ordinary radiation thermometer, the measurement accuracy is reduced under the influence of the scattered cooling water in an environment where the cooling water is scattered. As a countermeasure, it is sufficient to secure a gap where there is no water cooling device in the vicinity of the thermometer installation position, and to remove the cooling water scattered by performing water purge or air purge in this gap, but this does not allow the water cooling device to be installed. The gap increases and the cooling capacity of the entire water cooling device decreases. Further, even if the reduction in cooling capacity is acceptable, removal means such as water purge and air purge must be provided. Therefore, in the present invention, in order to make the measured value of the steel sheet temperature less susceptible to the scattered cooling water, the radiation temperature measurement is performed by detecting thermal radiation light in a band of 1.1 μm or less with little attenuation by water. Therefore, it is desirable that the measured value be measured by a thermometer capable of measuring temperature even in an environment where the cooling water is scattered.

  In the present invention, it is desirable to feedback control the water cooling device so that the deviation between the measured value of the coiling temperature and the target value is reduced.

  According to the present invention, each water cooling is performed even when a rolling operation is performed in which hot rolling conditions such as the rolling speed and the temperature or thickness of the steel plate at the exit side of the finish rolling mill are changed during the hot rolling. All target temperatures of the apparatus can be corrected and set appropriately and quickly, whereby the coiling temperature of the steel sheet can be accurately controlled to the target temperature.

BEST MODE FOR CARRYING OUT THE INVENTION The best mode for carrying out a method and apparatus for producing a hot-rolled steel sheet according to the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is an explanatory view showing a main part of a manufacturing apparatus 20 of the present embodiment for manufacturing a hot-rolled steel sheet. In FIG. 1, reference numeral 1 indicates a steel plate, reference numeral 2 indicates a part of the finishing rolling mill, reference numeral 3 indicates a conveyance table, reference numeral 4 indicates a winding device, and reference numeral 5 indicates n controllable elements. A water cooling device including a cooling header and a valve for adjusting the amount of water supplied to these cooling headers is shown. Reference numeral 7 denotes a winding thermometer, reference numeral 8 denotes an intermediate thermometer, and reference numeral 9 denotes a steel plate thickness measuring device. 10 is a steel plate speed measuring device, 11 is a steel plate temperature predicting device, 12 is a cooling control device for controlling the water amount adjusting valve, and is a result winding measured by a winding thermometer 7. It has a feedback control function that reduces the difference between the temperature and the target winding temperature. Hereinafter, the steel plate temperature prediction device 11 and the cooling control device 12 are collectively referred to as a controller 13.

  The water cooling device 5 has a total of n cooling headers arranged in parallel in the conveying direction of the steel plate 1. One region where these n cooling headers are arranged is called a cooling zone. The water cooling device 5 has a structure installed up and down so as to sandwich the transfer table 3. A water amount adjusting valve is provided for each cooling header, and a valve operation command is transmitted from the cooling control device 12 to the water cooling device 5 via the valve operation command distribution device 14 so that each valve is controlled. Yes.

  FIG. 2 is an explanatory diagram illustrating a state of signal transmission / reception of the first control controller 13a, the second control controller 13b, and the third control controller 13c included in the control controller 13 in FIG.

  The water cooling device 5 has three water cooling devices 5a to 5c having the basic configuration shown in FIG. 1 on the transfer table 3, and the surface temperature of the steel plate 1 is on the entry side of the three water cooling devices 5a to 5c. A finish outlet thermometer 6, a first intermediate thermometer 8b, and a second intermediate thermometer 8c are installed.

  FIG. 2 shows a case where both the first intermediate thermometer 8b and the second intermediate thermometer 8c are installed above the steel plate 1, but the present invention is not limited to this, and is installed below the steel plate 1. You may do it.

  In addition, since both the first intermediate thermometer 8b and the second intermediate thermometer 8c are arranged close to the water cooling devices 5a to 5c, the cooling on the steel plate 1 which becomes a disturbance factor in the measurement of the surface temperature. It may be difficult to remove water. Therefore, the first intermediate thermometer 8b and the second intermediate thermometer 8c are less attenuated by water through the purge water injected from the nozzle so that the temperature can be measured even in an environment where the cooling water is scattered. It is desirable to install a radiation thermometer that detects thermal radiation light in a band (for example, 0.9 μm). As a steel sheet surface temperature measuring device using such a radiation thermometer, the device disclosed by Unexamined-Japanese-Patent No. 2006-17589 can be illustrated. This device includes a radiation thermometer arranged opposite to the steel plate 1, and is a device for measuring the surface temperature of the steel plate 1 by detecting thermal radiation emitted from the surface of the steel plate 1 with a radiation thermometer, The minimum spread of the edge portion of the steel sheet 1 based on the intersection of the optical axis of the radiation thermometer with the interface between the optical path stable region and the optical path unstable region in the region through which the optical path of the thermal radiation detected by the radiation thermometer passes. The angle is set to 75 ° C. or higher.

Furthermore, although the case where the water cooling device 5 is divided | segmented into the three water cooling devices 5a-5c is shown, it is not limited to this, You may make it divide the water cooling device 5 into 2 or 4 or more. .
The controller 13 includes at least one controller (the first controller 13a in FIG. 2) in all the water cooling devices (FIG. 2) installed in the section from the inlet side thermometer 6 to the winding thermometer 7. Then, it is comprised so that three of the water-cooling apparatuses 5a-5c) may be controlled.

  The valve operation commands output from the first controller 13a are not directly transmitted to the water cooling devices 5a to 5c, but are once aggregated by the valve operation command distributor 14 and distributed to the water cooling devices 5a to 5c. Is output.

  Further, the controller 13 includes at least one water-cooling unit (second control controller 13b in FIG. 2) installed in the section from the inlet side thermometer 6 to the winding thermometer 7. It is configured to control the device (two of the water cooling devices 5b and 5c in FIG. 2).

  The valve operation commands output from the second controller 13b are not directly transmitted to the water cooling devices 5b and 5c, but are once aggregated by the valve operation command distributor 14 and distributed to the water cooling devices 5b and 5c. Is output.

  Further, the controller 13 includes at least one water-cooling unit (3rd controller 13c in FIG. 2) installed in the section from the inlet side thermometer 6 to the winding thermometer 7. It is configured to control the device (water cooling device 5c in FIG. 2).

  The valve operation commands output from the third controller 13c are not directly transmitted to the water cooling device 5c, but are once aggregated by the valve operation command distributor 14 and output to each water cooling device 5c.

  The hot rolled steel sheet manufacturing apparatus 0 of the present embodiment is configured as described above. Next, when performing the operation which changes the passage speed (rolling speed) of the steel plate 1 in the case of hot rolling in the middle of hot rolling using this manufacturing apparatus 1, all of each water cooling apparatus 5a-5c. A situation in which a hot rolled steel sheet is manufactured by correcting and setting the temperature appropriately and quickly will be described.

  As shown in FIG. 2, hot rolling of the steel sheet 1 is performed by a hot rolling mill 1 at a predetermined rolling speed. Here, it is assumed that accelerated rolling is performed to increase the rolling speed in order to prevent the temperature drop of the steel sheet 1 during hot rolling, and this case will be described.

  In this case, when the steel plate 1 rolled by the finish rolling mill 2 passes through the finish outlet thermometer 6, the temperature of the steel plate 1 is measured by the finish outlet thermometer 6 at a predetermined cycle (for example, a cycle of 0.4 to 2.0 seconds). Is measured, and the thickness of the steel plate 1 is measured by the steel plate thickness measuring device 9. At the same time, sampling points are set on the surface of the steel plate 1 at the same time.

  The steel plate temperature prediction device of the first controller 13a is the temperature of the sampling point, the plate thickness, the speed of the steel plate 1 when passing through the water cooling devices 5a, 5b, 5c (the rolling speed after change), and the steel plate 1 The sampling point is a winding thermometer based on the specific heat and density of each of the above, the valve opening of each cooling header among the first water cooling device 5a to the third water cooling device 5c, the water temperature of the cooling water, and the air temperature. When the temperature reaches 7, the temperature of the steel sheet 1, that is, the coiling temperature is predicted. A method for predicting the coiling temperature will be described.

For zone being cooled by the cooling water flowing out from the cooling headers of the water-cooling bodies 5a to 5c device, the temperature drop .DELTA.Tw _i by water cooling calculated using the water cooling unit temperature drop prediction equation (4) below. On the other hand, except for those zones for the air cooling zone is a zone which is cooled only by air, the amount of temperature drop .DELTA.Ta _i calculated using air cooling unit temperature drop formula (5), at the finishing outlet thermometer 6 The predicted value of the coiling temperature is obtained by subtracting the predicted temperature drop of all zones from the measured actual temperature.

Here, i: subscript representing a zone, n: number of zones, W: water density (m ³ / m ² hr), U: valve opening (%), α _Li : heat transfer coefficient of water cooling part (kcal / ^{m 2 hr ℃), a,} b: constant (-), _{t i:} zone passing time (hr), _{L i:} zone length (m), _{v i:} rolling speed of the steel sheet (m / sec), ΔTw _i : Temperature drop in water-cooled part (° C), ΔTa _i : temperature drop in air-cooled part (° C), c: specific heat (kcal / kg ° C), ρ: density (kg / m ³ ), h: plate thickness (m ), T _i : Temperature of steel plate in each zone (° C.), T _L : Water temperature (° C.), T _E : Air temperature (° C.), σ: Stefan-Boltzmann constant, ε: Emissivity (−), α _Ei : Air cooling Part heat transfer coefficient (kcal / m ² hr ° C.), T _C : predicted value of coiling temperature (° C.), T _F : finishing outlet temperature (° C.).

  When the predicted value of the coiling temperature is predicted to be higher than the target value of the coiling temperature, the cooling control of the first controller 13a is performed until the predicted value of the coiling temperature matches the target value of the coiling temperature. The device performs a valve operation simulation of the cooling header among the first water cooling device 5a, the second water cooling device 5b, and the third water cooling device 5c as follows, and calculates and outputs an operation command. The order of performing the valve operation of the water cooling devices 5a to 5c includes operation order information prepared in advance, and the operation is performed according to this.

(I) Increase the opening of the valve whose valve opening is not 100% in the cooling header that is flowing out the cooling water.
(Ii) If the valve openings of all the cooling headers that are flowing out of the cooling water are 100%, the valve opening having the highest operation order in the cooling header that is not flowing out of the cooling water is increased, and cooling is performed. Start.

  If the predicted value of the coiling temperature is predicted to be lower than the target value of the coiling temperature, the valve operation simulation of the cooling header is performed as follows until the predicted value of the coiling temperature matches the target value of the coiling temperature. To calculate and output an operation command.

(I) The opening degree of the valve whose valve opening is less than 100% is reduced in the cooling header that is flowing out the cooling water.
(Ii) If the valve opening degree of all the cooling headers flowing out of the cooling water is 100%, the opening degree of the lowest valve in the water cooling apparatus is reduced.

  When the predicted value of the coiling temperature is predicted to coincide with the target value of the coiling temperature, valve operation is not performed, and the valve opening when used for predicting the coiling temperature is output as it is as a valve operation command.

  At this time, in order to reduce the deviation between the actual value of the coiling temperature measured by the coiling thermometer 7 and the target value of the coiling temperature, the valve operation command is corrected by the feedback control function of the cooling control device. The valve operated by the feedback control function operates the valve closest to the winding thermometer 7 among the operable valves.

  Thus, although the 1st controller 13a outputs the valve operation command with respect to all the water-cooling apparatuses 5a-5c, the prediction apparatus of a steel plate temperature estimates the valve operation command output from the 1st controller 13a. A valve operation command for controlling the winding temperature to a predetermined temperature is calculated in a state where all the water-cooling apparatuses 5a to 5c are controllable, although the amount is inaccurate due to the estimated temperature of the winding temperature. For this reason, even if it is a case where the accelerated rolling which raises the rolling speed of the steel plate 1 in the case of hot rolling is performed in the middle of hot rolling, all the target temperature of each water-cooling apparatus 5a-5c is appropriately and rapidly. The sampling point of the steel sheet 1 can be controlled to a predetermined coiling temperature after effectively using the cooling capacity of the water cooling devices 5a to 5c.

  Subsequently, when the sampling point moves on the transport table 3 toward the winding device 4 and passes through the first intermediate thermometer 8b, the steel plate temperature prediction device of the second controller 13b determines the sampling point. The temperature and thickness measured by the first intermediate thermometer 8b, the passing speed (rolling speed) of the steel plate 1 passing through the water cooling devices 5a to 5c, the specific heat and density of the steel plate 1, the second water cooling device 5b and The winding temperature when the sampling point reaches the winding thermometer 7 is predicted using the valve opening of each cooling header of the third water cooling device 5c, the water temperature of the cooling water, and the air temperature. The method for predicting the winding temperature is the same as the method performed by the first controller 13.

  The valve operation methods and operation command output methods of the water cooling devices 5a to 5c are substantially the same, but the second controller 13b sends the valve operation command distribution device 14 to the second water cooling device 5b and the third water cooling device 5c. The difference is that a valve operation command is output to the two water cooling devices.

  The second controller 13b outputs a valve operation command for the second water cooling device 5b and the third water cooling device 5c. The valve operation command is more than the valve operation command output by the first controller 13a. Since the temperature prediction section is short and the prediction error of the coiling temperature is small, the sampling point on the steel plate 1 can be controlled to a predetermined coiling temperature with higher accuracy.

  The valve operation commands for the second water cooling device 5b and the third water cooling device 5c output by the first controller 13a and the operation commands output by the second controller 13b are set according to the same valve operation sequence. For this reason, the difference in the operation command is a correction for further improving the control accuracy of the coiling temperature.

  Further, when the sampling point moves on the transport table 3 toward the winding device 4 and passes through the second intermediate thermometer 8c, the steel plate temperature prediction device of the third controller 13c is the first sampling point. 2, the temperature measured by the intermediate thermometer 8c, the plate thickness of the steel plate 1 and the speed of passing through the third water cooling device 5c, the specific heat and density of the steel plate 1, and the individual cooling in the third water cooling device 5c. Based on the valve opening of the header, the coolant temperature, and the air temperature, the temperature of the steel sheet 1 when the sampling point reaches the winding thermometer 7, that is, the winding temperature, is predicted. The method for predicting the coiling temperature is the same as the method performed by the first controller 13a.

  The valve operation method and operation command output method of the third water cooling device 5c are substantially the same, but the third controller 13c outputs the valve operation command to the valve operation command distribution device 14 only for the third water cooling device 5c. Is different.

  The third controller 13c outputs a valve operation command for the third water cooling device 5c, and this valve operation command has a shorter temperature prediction interval than the valve operation command output by the second controller 13b. Since the temperature prediction error is reduced, the sampling point on the steel plate can be controlled to a predetermined winding temperature with higher accuracy.

  In addition, since the valve operation command with respect to the 3rd water cooling apparatus 5c which the 2nd controller 13b output, and the operation command which the 3rd controller 13c output are set according to the same valve operation sequence, operation command The difference is a correction for further improving the control accuracy of the coiling temperature.

  In this way, the first controller 13a outputs the valve operation commands of the first water cooling device 5a, the second water cooling device 5b, and the third water cooling device 5c to the valve operation command distribution device 14, and the second control. The controller 13b outputs the valve operation commands of the second water cooling device 5b and the third water cooling device 5c to the valve operation command distribution device 14, and the third control controller 13c further outputs the valve operation commands of the third water cooling device 5c. Is output to the valve operation command distributor 14.

  As described above, first, the first controller 13a outputs a valve operation command as a base for controlling the winding temperature to a predetermined temperature. Although this valve operation command has a long temperature prediction interval to the winding thermometer 7, the prediction error of the winding temperature is large, which is disadvantageous in terms of control accuracy, but from the finishing outlet thermometer 6 to the winding thermometer 7 Since all the water cooling devices 5a to 5c existing in between are the operation targets, it is possible to prevent the winding temperature from deviating from the target temperature by effectively using the cooling capacity of the water cooling devices 5a to 5c.

  The valve operation command for the second controller 13b to control the winding temperature to a predetermined temperature uses the actual temperature measured by the first intermediate thermometer 18b. Since the temperature prediction section is shortened, the prediction error of the coiling temperature is relatively small, so that the control accuracy can be expected to be improved, and the operation command output by the first controller 13a is improved in the coiling temperature control accuracy. Can be modified.

  Further, the valve operation command for the third controller 13c to control the winding temperature to a predetermined temperature uses the actual temperature measured by the second intermediate thermometer 8c, and the temperature up to the winding thermometer. Since the prediction interval is shorter and the prediction error of the coiling temperature is small, the highest control accuracy can be expected, and the operation command output by the second controller 13b is further modified so that the control accuracy of the coiling temperature is improved. be able to.

  The cooling operation of all the water cooling devices 5a to 5c is made effective by outputting the valve operation commands output from the plurality of control controllers 13a to 13c to the water cooling devices 5a to 5c by the above-described distribution method and cooling the steel plate 1. And the control accuracy of the coiling temperature can be improved.

  As described above, the invention in which one water cooling device 5 shown in FIG. 8 is controlled by one controller 13 and the plurality of water cooling devices 5 shown in FIG. 9 are in a one-to-one relationship with these water cooling devices. The invention is controlled by the same number of corresponding controller 13 and the control section of one controller and one water cooling device correspond one-to-one, and each control controller controls each target value. Known before filing.

  On the other hand, the present invention is formally common with the invention of FIG. 9 in that it includes the same number (two or more) of controller as the water cooling device, but as shown in FIG. The section is characterized by the section from the inlet side thermometer of the water cooling device to the winding thermometer.

  With this structure, at least one controller (first controller 13a in FIG. 2) outputs a valve operation command with all the water cooling devices 5a to 5c as control targets, so that the cooling capacity of all the water cooling devices 5a to 5c is Can be used effectively. In addition, a control controller (third control controller 13c in FIG. 2) corresponding to a short control section improves the control accuracy of the coiling temperature. The control controller located in the middle (second control controller 13b in FIG. 2) has an intermediate role of effectively using the cooling capacity and improving the control accuracy.

  Although there is a portion where valve operation commands output from the respective controller 13a to 13c to the respective water cooling devices 5a to 5c overlap, the valve operation command distribution device 14 appropriately distributes this so that the cooling capacity of the water cooling devices 5a to 5c is obtained. It is possible to improve the control accuracy of the coiling temperature while effectively using.

  In the description of the above embodiment, an example in which the hot rolling condition changed during the hot rolling is the rolling speed of the hot rolling is taken as an example. However, the present invention is not limited to this embodiment, and the present invention is similarly applied to the case where the hot rolling condition is the temperature or thickness of the steel plate on the exit side of the finishing mill of the hot rolling mills. The As described above, in the actual manufacture of a hot-rolled steel sheet, the temperature and thickness of the steel sheet on the exit side of the finish rolling mill may deviate from the set value due to some cause.

  In such a case, the measured values of the temperature and thickness of the steel sheet on the exit side of the finish rolling mill and the temperature of the steel sheet on the inlet side of the water cooling apparatus located on the most upstream side of the plurality of water cooling apparatuses. Based on the above, the setting value of the cooling condition for all of the plurality of water cooling devices capable of setting the coiling temperature of the steel sheet as a target value is obtained, and further, among the above-described fluctuation values and the plurality of water cooling devices. Corrected the set value of the cooling condition obtained for at least one or two or more water cooling devices based on the measured value of the temperature of the steel plate on the inlet side of one or more water cooling devices other than the water cooling device located on the most upstream side And set it. As a result, even when the temperature and thickness of the steel sheet on the exit side of the finish rolling mill fluctuate, all target temperatures of each water cooling device can be appropriately and quickly corrected and set. The coiling temperature can be accurately controlled to the target temperature.

The present invention will be described more specifically with reference to examples.
Drawing 3 is an explanatory view showing typically the whole composition of the manufacture device of the hot rolled sheet steel of this example.
Three water-cooling devices 5a to 5c having the basic configuration shown in FIG. 2 are provided on the transfer table 3, and the surface temperature of the steel sheet 1 can be measured on the entry side of the three water-cooling devices 5a to 5c. A finishing exit thermometer 6, a first intermediate thermometer 8 b and a second intermediate thermometer 8 c are installed.

  The water cooling devices 5a and 5b have a gap sufficient to perform water purge and air purge and remove the scattered cooling water. Therefore, the first intermediate thermometer 8b takes ordinary measures after taking these measures. A radiation thermometer is installed. On the other hand, since the water cooling devices 5b and 5c do not have a sufficient gap and cannot sufficiently take measures for removing the cooling water, the temperature that can be measured even in the environment where the cooling water scatters as the second intermediate thermometer 8c. A total was installed. The intermediate thermometer 8c is installed on the lower surface side of the steel plate 1 due to the structure of the intermediate thermometer 8c.

  The number of control controllers 13a to 13c is the same as that of the water cooling devices 5a to 5c, and at least one control controller 13a is one or more water cooling devices installed in the section from the inlet side thermometer 6 to the winding thermometer 7. Control 5a-5c.

A hot-rolled steel sheet was manufactured under the following conditions using the manufacturing apparatus shown in FIG.
Steel type: 440 MPa class high strength hot-rolled steel sheet Thickness: 3.5 mm
Target winding temperature: 500 ° C
Steel plate speed: 570 mpm → 650 mpm (accelerated rolling)
The length of the first water cooling device 5a: 32 m
The length of the second water cooling device 5b: 40 m
Length of third water cooling device 5c: 40m
Water density of water cooling device 5a: 1.1 m ³ / m ² hr (upper surface), 0.8 m ³ / m ² hr (lower surface)
In both cases, the water density of the water cooling device 5b when the valve opening is 100%: 0.6 m ³ / m ² hr (upper surface), 0.5 m ³ / m ² hr (lower surface)
In both cases, the water density of the water cooling device 5c when the valve opening degree is 100%: 0.6 m ³ / m ² hr (upper surface), 0.5 m ³ / m ² hr (lower surface)
When the valve opening degree is 100%, the number of valves of the water cooling device 5a: 78 The number of valves of the water cooling device 5b: 45 The number of valves of the water cooling device 5c: 82

  FIG. 4 is a result of the cooling control of the comparative example in which the cooling control is performed by the cooling control device of FIG. 9, the actual finishing outlet temperature value in the longitudinal direction of the steel plate 1, the measured value of the first intermediate thermometer 8 b, It is a graph which shows the measured value of the intermediate | middle thermometer 8c of No. 2, and winding temperature actual value.

  As shown in the graph of FIG. 4, the target value of the intermediate temperature 1 was 700 ° C., and the target value of the intermediate temperature 2 was 560 ° C. Although the intermediate temperature 1 could be controlled according to the target, both the intermediate temperature 2 and the coiling temperature reached the upper limit of the cooling capacity of the water cooling device and were saturated, and thus deviated 30 to 40 ° C. higher than the target temperature. .

  On the other hand, FIG. 5 is a result of the cooling control of the present invention example in which the cooling control is performed using the first controller 13a, the second controller 13b, and the third controller 13c shown in FIG. It is a graph which shows the finishing outlet temperature actual value of the longitudinal direction of the steel plate 1, the measured value of the 1st intermediate thermometer 8b, the measured value of the 2nd intermediate thermometer 8c, and the winding temperature actual value.

  As shown in FIG. 5, the actual winding temperature is controlled in the vicinity of the target 500 ° C., and is controlled within the target ± 15 ° C.

Example 1 showed the effect when the finish rolling speed was changed during rolling, but in this example, the case where the exit temperature of the finish rolling machine is changed will be described.
The manufacturing apparatus of the hot-rolled steel sheet of this example is exactly the same as that of Example 1, and a hot-rolled steel sheet was manufactured under the following conditions using this manufacturing apparatus.

Steel type: 290 MPa class hot-rolled steel sheet thickness: 4.3 mm
Target winding temperature: 600 ° C
Steel plate speed: 620 mpm (no acceleration)
The length of the first water cooling device 5a: 32 m
The length of the second water cooling device 5b: 40 m
Length of third water cooling device 5c: 40m
Water density of water cooling device 5a: 1.1 m ³ / m ² hr (upper surface), 0.8 m ³ / m ² hr (lower surface)
In both cases, the water density of the water cooling device 5b when the valve opening is 100%: 0.6 m ³ / m ² hr (upper surface), 0.5 m ³ / m ² hr (lower surface)
In both cases, the water density of the water cooling device 5c when the valve opening degree is 100%: 0.6 m ³ / m ² hr (upper surface), 0.5 m ³ / m ² hr (lower surface)
When the valve opening degree is 100%, the number of valves of the water cooling device 5a: 78 The number of valves of the water cooling device 5b: 45 The number of valves of the water cooling device 5c: 82

  FIG. 6 is a result of the cooling control of the comparative example in which the cooling control is performed by the cooling control device of FIG. 9, and the actual finishing outlet temperature value in the longitudinal direction of the steel plate 1, the measured value of the first intermediate thermometer 8b, and the first It is a graph which shows the measured value of the intermediate | middle thermometer 8c of No. 2, and winding temperature actual value.

  As shown in the graph of FIG. 6, the target value of the intermediate temperature 1 was 780 ° C., and the target value of the intermediate temperature 2 was 710 ° C. With respect to the intermediate temperature 1, the finishing outlet temperature after the central portion in the longitudinal direction of the steel sheet reaches the upper limit of the cooling capacity of the water cooling device 5a at a high temperature portion and is saturated. And at the intermediate temperature 2, the water cooling device 5b could be controlled according to the target without reaching the upper limit of the cooling capacity, but the winding temperature was 20-30 ° C. higher than the target temperature because the water cooling device 5c reached the upper limit of the cooling capacity. Highly off.

  On the other hand, FIG. 7 is a result of the cooling control of the present invention example in which the cooling control is performed using the first controller 13a, the second controller 13b, and the third controller 13c shown in FIG. It is a graph which shows the finishing outlet temperature actual value of the longitudinal direction of the steel plate 1, the measured value of the 1st intermediate thermometer 8b, the measured value of the 2nd intermediate thermometer 8c, and the winding temperature actual value.

  FIG. 7 shows the control result. The intermediate temperature 1 is the same as that in FIG. 6 because the water cooling device 5a reaches the upper limit of the cooling capacity and is saturated, but the water cooling device 5b having sufficient cooling capacity is effective. By using this, the actual winding temperature could be controlled around the target 600 ° C.

It is explanatory drawing which shows the principal part of the manufacturing apparatus of this Embodiment which manufactures a hot-rolled steel plate. It is explanatory drawing which shows the condition of transmission / reception of the signal of the 1st control controller contained in the control controller in FIG. 1, a 2nd control controller, and a 3rd control controller. It is explanatory drawing which shows the structure of the manufacturing apparatus of the hot rolled sheet steel of an Example. 6 is a graph showing the results of a comparative example in Example 1. 3 is a graph showing the results of an example of the present invention in Example 1. 6 is a graph showing the results of a comparative example in Example 2. 6 is a graph showing the results of an example of the present invention in Example 2. It is explanatory drawing which shows typically an example of the manufacturing apparatus of the conventional hot-rolled steel plate. It is explanatory drawing which shows typically an example of the manufacturing apparatus of the conventional hot-rolled steel plate. It is a graph which shows an example of the temperature of the steel plate cooled with a water cooling device over time.

Explanation of symbols

0, 20 Manufacturing apparatus for hot-rolled steel sheet 1 Steel sheet 2 Finishing rolling mill 3 Conveying table 4 Winding device 5, 5a-5c Water cooling device 6 Finishing exit thermometer 7 Winding thermometers 8, 8b, 8c Intermediate thermometer 9 Steel plate Thickness measurement device 10 Steel plate speed measurement device 11 Steel plate temperature prediction device 12 Cooling control device 13, 13a-13c Control controller 14 Valve operation command distribution device

Claims (5)

From the plurality of water cooling devices arranged in parallel in the transport direction of the steel sheet to the steel sheet transported by the transport table after hot rolling by a hot rolling mill, a predetermined hot After cooling the steel sheet by injecting cooling water under a predetermined cooling condition by predicting the coiling temperature of the steel sheet by calculation based on the rolling conditions, the coil is wound around a coil by a winder. When manufacturing
In the middle of the hot rolling, when the hot rolling is continued by changing to other hot rolling conditions different from the predetermined hot rolling conditions,
Based on the other hot rolling conditions and the measured value of the temperature of the steel plate on the inlet side of the water cooling device located on the most upstream side of the plurality of water cooling devices, the coiling temperature of the steel plate is set as the target value. It is possible to obtain a set value of cooling conditions for all of the plurality of water cooling devices, and other than the other hot rolling conditions and the water cooling device located on the most upstream side among the plurality of water cooling devices Correcting and setting the set value of the cooling condition obtained for at least the one or more water cooling devices based on the measured value of the temperature of the steel sheet on the entry side of the one or more water cooling devices ; and
The water cooling device has a plurality of water amount adjustment valves that can independently control the opening degree and adjust the amount of the cooling water to be injected, and the cooling condition is the opening degree of the water amount adjustment valve. <br/> A method for producing a hot-rolled steel sheet characterized by the above.   The hot-rolled steel sheet manufacturing method according to claim 1, wherein the hot-rolling condition is a rolling speed of the hot-rolling or a temperature of the steel sheet on the exit side of a finishing mill of the hot-rolling mill. Method. The measured value of the temperature of the steel sheet is a temperature that can be measured even in an environment where the cooling water is scattered by detecting thermal radiation in a band of 1.1 μm or less, which is less attenuated by water, and performing radiation temperature measurement. The method for producing a hot-rolled steel sheet according to claim 1 or 2 , which is a value measured by a meter. The method for producing a hot-rolled steel sheet according to any one of claims 1 to 3 , wherein the water cooling device is feedback-controlled so that a deviation between the measured value of the coiling temperature and the target value decreases. A hot rolling mill for hot rolling steel sheets;
A transport table for transporting a steel plate that has been hot-rolled by the hot rolling mill;
A winding device that winds a steel plate conveyed by the conveyance table around a coil;
A plurality of the steel plates are arranged in parallel in the conveying direction of the steel plate, and the coiling temperature of the steel plate is predicted by calculation based on predetermined hot rolling conditions toward the steel plate conveyed by the conveying table. A water cooling device for cooling the steel sheet by injecting cooling water under a cooling condition predetermined by
A thermometer for measuring the temperature of the steel plate on the entry side of each of the plurality of water cooling devices, and measuring the temperature of the steel plate on the outlet side of the water cooling device located on the most downstream side of the plurality of water cooling devices,
Furthermore, the control for controlling the winding temperature to the target temperature by controlling the plurality of water cooling devices based on the result of predicting the winding temperature of the steel sheet cooled by the plurality of water cooling devices by calculation. A hot-rolled steel sheet manufacturing apparatus comprising a controller,
The controller, during the hot rolling, when changing to another hot rolling condition different from the predetermined hot rolling condition to continue the hot rolling,
Based on the other hot rolling conditions and the measured value of the temperature of the steel plate on the inlet side of the water cooling device located on the most upstream side of the plurality of water cooling devices, the coiling temperature of the steel plate is a target value. The set values of the cooling conditions in all of the plurality of water cooling devices can be obtained, and the other hot rolling conditions and the water cooling devices other than the water cooling device located on the most upstream side among the plurality of water cooling devices Based on the measured value of the temperature of the steel plate on the inlet side of one or more of the water cooling devices, at least the setting value of the cooling condition obtained for the one or more of the water cooling devices is further corrected and set. ,as well as
The water cooling device has a plurality of water amount adjustment valves that can independently control the opening degree and adjust the amount of the cooling water to be injected, and the cooling condition is the opening degree of the water amount adjustment valve. <br/> An apparatus for producing a hot-rolled steel sheet.

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