JP2006122987A - Metal plate cooling control device and cooling control method - Google Patents

Abstract

A cooling control method for a metal plate capable of improving the accuracy of a winding temperature by simple correction.
The temperature of a metal sheet to be conveyed is lowered by adjusting the cooling conditions in a water cooling facility 4 arranged between the exit side of a finish rolling mill 1 and a winder 3 in a hot rolling process. The winding temperature of the metal plate is controlled to the target winding temperature. At this time, a temperature drop amount at the CTN position for achieving the target winding temperature is calculated by a heat transfer model, and the water cooling equipment 4 is adjusted to the cooling condition according to the calculated temperature drop amount. This is a cooling control method. The accuracy of cooling control can be improved by correcting the temperature drop calculated in the next heat transfer model with the learning term based on the proportional error or deviation between the temperature drop calculated with the heat transfer model and the actual temperature drop. To improve.
[Selection] Figure 1

Description

  The present invention relates to control for cooling a metal sheet hot-rolled by a finish rolling mill to a target coiling temperature based on a heat transfer model, and particularly in a hot rolling process effective for a thick metal sheet. The present invention relates to a plate cooling control device and a cooling control method.

  As a method for controlling the coiling temperature of the steel plate, for example, there is a cooling control method described in Patent Document 1. In the conventional cooling control method as described in Patent Document 1, the heat transfer coefficient related to heat removal in the heat transfer model is based on the deviation between the predicted temperature and the actual temperature calculated by the heat transfer model. In feed forward control in which the model learning terms are sequentially changed and updated, the accuracy of the steel sheet winding temperature is improved by increasing the accuracy of the predicted temperature of the next heat transfer model.

Further, based on the deviation between the predicted temperature and the actual temperature, there is a case where the cooling control is performed such that the water injection in the bank on the final stage side of the water cooling equipment is feedback controlled to reach the target winding temperature.
JP-A-6-218414

  However, in order to update the model learning term of the heat transfer coefficient of the heat transfer model, change the learning value, calculate the predicted winding temperature by the heat transfer model, compare the actual winding temperature with the predicted winding temperature, Since it is necessary to perform the convergence calculation so that the error becomes the convergence condition (the actual winding temperature and the predicted winding temperature are the same or within the specified tolerance), the more complex the heat transfer model is, the more learning is required. It takes time to calculate the value, and the reflection of the learning value is delayed. That is, the length of the metal plate wound up without the learning value being updated is increased.

In particular, when cooling control is performed on a short metal plate such as a thick object (for example, within a length of 100 m), it is desired to reflect the learning term as soon as possible.
Further, the shorter the length of the target metal plate, the more difficult the control by the feedback. In addition, even if the final target winding temperature is within a predetermined tolerance, if feedback control is performed in the middle, a large supercooling is temporarily performed, so that a pearlite structure is temporarily formed. In fact, there is a risk of quality failure.
The present invention has been made paying attention to such points, and an object of the present invention is to provide a metal plate cooling control method capable of improving the accuracy of the winding temperature by simple correction.

In order to solve the above-mentioned problems, the invention described in claim 1 of the present invention adjusts the cooling conditions in the water cooling facility arranged between the finish rolling mill exit side and the winder in the hot rolling process. When the temperature of the metal plate being transported is lowered and the winding temperature of the metal plate is controlled to the target winding temperature, the amount of temperature drop for achieving the target winding temperature is calculated using a heat transfer model. A metal plate cooling control device including a temperature drop prediction unit that performs the above and a water injection control unit that adjusts the water cooling facility to the cooling condition according to the calculated temperature drop amount,
Based on an error ratio or deviation between the temperature drop amount calculated with the heat transfer model and the actual temperature drop amount, a correction unit for correcting the temperature drop amount calculated with the next heat transfer model is provided. is there.

Next, the invention described in claim 2 is a metal plate conveyed by adjusting the cooling conditions in a water cooling facility arranged between the finish rolling mill exit side and the winder in the hot rolling process. When controlling the coiling temperature of the metal plate to the target coiling temperature by lowering the temperature, calculate the amount of temperature decrease to achieve the target coiling temperature with the heat transfer model, and according to the calculated temperature decrease A metal plate cooling control method for adjusting the water cooling equipment to the cooling conditions,
The temperature drop amount calculated by the next heat transfer model is corrected based on the error ratio or deviation between the temperature drop amount calculated by the heat transfer model and the actual temperature drop amount.

Next, the invention described in claim 3 provides a water cooling zone and an air cooling zone from the upstream side to the configuration described in claim 2 from the upstream side of the finish rolling mill to the winder. The above water cooling equipment is arranged in the zone,
Based on at least the target winding temperature and the actual temperature at the finish rolling mill delivery side, the predicted temperature drop at the water cooling zone exit side is predicted using the heat transfer model, and the temperature drop calculated by the heat transfer model and the water cooling zone exit side are calculated. The temperature drop calculated by the next heat transfer model is corrected on the basis of the actual temperature drop.

Next, the invention described in claim 4 is directed to the structure described in claim 1, wherein at least the target coiling temperature and the finish rolling mill actual temperature are used in the heat transfer model and the water cooling zone outlet side and the air cooling zone outlet. Estimate each predicted temperature drop on the side, correct by the error ratio between the temperature drop at the water cooling zone outlet calculated by the heat transfer model and the actual temperature drop at the water cooling zone outlet, and the heat transfer model The correction based on the deviation between the temperature drop at the air cooling zone outlet calculated in step 1 and the actual temperature drop at the air cooling zone outlet is applied to the temperature drop calculated by the next heat transfer model. is there.
Next, the invention described in claim 5 is characterized in that, for the configuration described in any one of claims 2 to 4, the heat transfer model uses a differential equation. It is.

  By adopting the present invention, it is assumed that the same calculation error will occur at the next calculation of the predicted temperature drop, and the predicted temperature drop calculated by the heat transfer model is changed without changing the heat transfer model itself. Correction is made based on the error so far, and the cooling capacity of the cooling equipment is set based on the predicted temperature drop after correction, so that correction can be reflected at an early stage and cooling control accuracy can be improved, that is, winding temperature accuracy can be improved To do.

Next, embodiments according to the present invention will be described with reference to the drawings.
FIG. 1 is a schematic diagram of a cooling control device in a hot rolling process. In the present embodiment, a steel plate is described as an example of the metal plate, but the present invention can also be applied to cooling control equipment for other metal plates.
In this embodiment, as shown in FIG. 1, the steel plate 2 which is a metal plate hot-rolled by the finish rolling mill 1 is continuously conveyed toward the winder 3 by the run-out table and continuously wound. It is wound around the take-up machine 3 to form a coil.

A water cooling zone and an air cooling zone are provided from the upstream side along the pass line from the exit side of the finish rolling mill 1 to the winder 3, and the water cooling zone is a water cooling system composed of a plurality of banks that can be independently controlled for water injection. The equipment 4 is arranged and the steel plate 2 can be rapidly cooled by pouring water toward the steel plate 2.
In each bank, the cooling condition of the water cooling equipment 4 is adjusted by controlling the presence and amount of water injection according to a command from the controller 6.

Thermometers 7, 8, and 9 are installed on the exit side of the finish rolling mill 1, the exit side of the water cooling zone, and the exit side of the air cooling zone, respectively, and each thermometer 7, 8, 9 passes through each position. The actual temperature value of the steel plate 2 to be measured is continuously measured and output to the controller 6.
Here, in the following description, the exit side of the finish rolling mill 1 may be referred to as FDT, the water-cooling zone exit side as CTN, and the air-cooling zone exit side (winding temperature measurement position) as CTS. Moreover, the said steel plate 2 is virtually divided into pieces for every predetermined length (for example, every 1 m) along the length direction, and the bank and the amount of water injection used for each piece are adjusted, respectively. Cooled to temperature.

The controller 6 includes a temperature drop prediction unit 6A, a correction unit 6B, and a water injection control unit 6C. The controller 6 is supplied with information such as the conveying speed of the steel plate 2 and the thickness of the steel plate 2 after finish rolling.
Each time the steel plate 2 advances by a predetermined length (for example, 1 m), the temperature drop prediction unit 6A inputs the thermometer performance in the FDT and the latest transport prediction result to the heat transfer model, and the piece portion at the FDT position is Calculate the predicted CTN temperature when moving to the CTN position (by subtracting the actual thermometer at the FDT from the predicted CTN temperature, the predicted temperature drop at the CTN will be calculated) using the heat transfer model. The predicted temperature for each part is output to the temperature drop correction unit 6B.

  As the heat transfer model, a known heat transfer model can be used, but in the present embodiment, a heat transfer model using the crank Nicholson method or other differential equations is used. Note that the differential temperature model, which is a heat transfer model that uses a differential equation, cannot calculate the heat transfer coefficient in reverse, and in order to learn the heat transfer coefficient, the convergence calculation is performed while changing the size of the heat transfer coefficient. It is necessary to do this, and the computation load is heavy and it is difficult to quickly calculate the learning value.

In the correction unit 6B, the learning values TCFn and TCFs for correction are continuously calculated for each of the water-cooled portions of FDT to CTN and the air-cooled portions of CTN to CTS, based on the error ratio or deviation of the temperature drop in that range. Calculate and update to.
Then, the CTS predicted temperature input from the temperature drop prediction unit 6A is corrected by the learned values TCFn and TCFs, and the corrected learned CTS predicted temperature is output to the water injection control unit 6C.

  In the water injection control unit 6C, based on the corrected predicted temperature drop amount obtained from the learned CTS predicted temperature and the actual FDT temperature, a bank or the like is selected for cooling the piece that has passed the current FDT position by a map or the like. The water injection amount of the bank is selected to calculate the water injection schedule which is the cooling condition of the piece, and the cooling control is performed according to the water injection schedule along the movement of the piece. In the above description, the temperature drop amount of the piece that will be rapidly cooled by the water cooling equipment 4 is corrected. However, when the learning term is reflected, the temperature drop is corrected for the piece that is in the middle of water cooling. Thus, the downstream water cooling condition may be changed.

Next, the method of this embodiment is demonstrated about the process of the said correction | amendment part 6B.
"Water-cooled part from FDT to CTN"
The learning value TCFn of the water-cooled portion of FDT to CTN is obtained from the error ratio of the temperature drop amount as follows.
If the value of the learning value due to the proportional error at a certain moment is defined as TCFn, TCFn can be expressed by the following equation.
TCFn = (FDT actual temperature-CTN actual temperature)
÷ (FDT actual temperature-CTN predicted temperature)

In this embodiment, the TCFn is calculated every time the predicted CTN temperature is obtained (each time the steel plate 2 advances by a predetermined length (for example, 1 m)), and the learning value TCFn is leveled and updated for each calculation. Then, the exponential smoothing method is adopted, the exponential smoothing coefficient G1 is calculated for the current TCFn, the (1-G1) is calculated for the previous update value TCFnold, and the learning value TCFnnew is sequentially updated as in the following equation.
TCFnnew = (1-G1) * TCFnold + G1 * TCFn
TCFnold ← TCFnnew
Here, the exponential smoothing coefficient G1 is a value of 0 ≦ G1 <1, and TCFnnew is updated more smoothly as the value is set to a smaller value, and the difference from the original data becomes smaller as the value approaches 1. The exponential smoothing coefficient G1 may be set to an appropriate value from experiments or the like.
Then, the amount of temperature drop in FDT to CTN is corrected by multiplying the learning value as in the following equation.
Temperature drop in FDT to CTN after correction
= TCFnold × (FDT actual temperature−CTN predicted temperature)

“Air-cooled part of CTN to CTS”
The learning value TCFs of the air-cooled portion in CTN to CTS is obtained from the temperature drop amount deviation as follows.
If the value of the learning value due to deviation at a certain moment is defined as TCFs, TCFs can be expressed by the following equation.
TCFs = (CTS actual temperature−CTS predicted temperature)
Actually, the deviation of the descent amount should be calculated in consideration of the actual CTN temperature and the predicted CTN temperature, but the above formula is used as a simplified CTN actual temperature = CTN predicted temperature.

In the present embodiment, the TCFs are calculated every time the CTS predicted temperature is obtained (each time the steel plate 2 advances by a predetermined length (for example, 1 m)), and the learning value TCFs is leveled and updated for each calculation. Then, the exponential smoothing method is adopted, the exponential smoothing coefficient G2 is calculated for the current TCFs, and (1-G2) is calculated for the previous update value TCFsold, so that the learning value TCFsnew is continuously updated.
TCFsnew = (1-G2) * TCFsold + G2 * TCFs
TCFsold ← TCFsnew

Here, the exponential smoothing coefficient G2 is a value of 0 ≦ G2 <1, and the TCFnnew is updated more smoothly as it is set to a smaller value, and the difference from the original data becomes smaller as the value approaches 1. The exponential smoothing coefficient G1 may be set to an appropriate value from experiments or the like.
Then, as shown in the following equation, the temperature correction is performed on the amount of temperature drop in CTN to CTS by the learning value.
Temperature drop in CTN to CTS after correction
= CTN predicted temperature -CTS predicted temperature + TCFsold

From the above, after both learning values are present, the CTS temperature calculated by the heat transfer model is corrected by the following equation and then output to the water injection control unit 6C.
CTS temperature after correction = FDT actual temperature-Amount of temperature drop from FDT to CTN after correction
-Amount of temperature drop in CTN to CTS after correction = FDT actual temperature-TCFnold x (FDT actual temperature-CTN predicted temperature)
-(CTN predicted temperature -CTS predicted temperature + TCFsold)

Next, functions and effects of the cooling control method will be described.
The steel sheet 2 is continuously finish-rolled, and the FDT actual temperature is measured every time the steel sheet 2 is conveyed for a predetermined length, and the predicted CTN temperature is calculated based on the actual FDT temperature and the target winding temperature (CTS predicted temperature). The water injection condition (cooling condition) for the piece part is set so as to be the amount of temperature drop in the CTN based on the FDT actual temperature and the predicted CTN temperature, and feed forward for each piece part. Control by water cooling.

At this time, in the present embodiment, the temperature drop amount at the CTN of the piece portion to be water-cooled and cooled is corrected by the error learning value according to the error ratio of the temperature drop amount at the CTN and the deviation of the temperature drop amount at the CTS. By doing so, the precision of cooling control improves and the precision of winding temperature improves.
Further, in the present embodiment, instead of calculating and updating the heat transfer coefficient model learning term of the heat transfer model itself as in the prior art, the calculated value calculated by the heat transfer model is changed so far as the proportional error of the temperature drop amount or By correcting by the deviation, the learning term can be reflected quickly, so that a portion that may become defective without reflecting the learning term on the front end side of each steel plate 2 can be reduced.

In addition, it is possible to start the correction in a shorter time by correcting the learning term with the information of the position at which the actual steel plate 2 has exited the water cooling zone before the actual steel plate 2 comes to the CTS position.
For example, since the steel plate 2 for the thick-walled pipe material is as short as about 100 m, when the correction is started after the tip portion passes through the CTS, the rear end portion of the steel plate 2 passes through the water cooling zone. Although there is a possibility that correction cannot be performed, this can be suppressed in this embodiment.

Here, the learning term in the air cooling zone is calculated and updated by the deviation because the learning term may be hunted if the error ratio is used. Since cooling control is substantially performed in the water cooling zone, the predicted temperature drop may be corrected using only the learning term in the water cooling zone without using the learning term in the air cooling zone.
Moreover, in the said embodiment, in order to produce a learning effect at an early stage, the learning term is calculated in two parts, a water cooling zone and an air cooling zone, but FDT to CTS are regarded as one zone, The amount of temperature drop may be corrected by a learning term based on the error ratio or deviation in CTS as described above.
Here, in this embodiment, the learning term is calculated and updated by the error ratio in the preceding water-cooling zone, and the learning term is calculated and updated by the deviation in the air-cooling zone, but the air-cooling zone is changed to the second water-cooling zone. It is also good.

It is a schematic block diagram which shows the cooling control equipment which concerns on embodiment based on this invention.

Explanation of symbols

FDT Finishing mill exit CTN Water cooling zone exit CTS Air cooling zone exit 1 Finish rolling mill 2 Steel plate 3 Winder 4 Water cooling equipment 6 Controller 6A Temperature drop prediction unit 6B Correction unit 6C Water injection control unit 7 Finishing mill exit side Thermometer 8 Thermometer on the exit side of the water cooling zone 9 Thermometer on the exit side of the air cooling zone (just before the winder)

Claims (5)

In the hot rolling process, the temperature of the metal plate to be conveyed is lowered by adjusting the cooling conditions in the water cooling facility arranged between the exit side of the finishing mill and the winder, and the metal plate is wound up. When controlling the temperature to the target winding temperature, a temperature drop prediction unit that calculates a temperature drop amount for achieving the target winding temperature by a heat transfer model, and the cooling condition according to the calculated temperature drop amount A metal plate cooling control device including a water injection control unit for adjusting equipment,
A metal plate comprising a correction unit that corrects the temperature drop amount calculated in the next heat transfer model based on an error ratio or deviation between the temperature drop amount calculated in the heat transfer model and the actual temperature drop amount. Cooling control device. In the hot rolling process, the temperature of the metal plate to be conveyed is lowered by adjusting the cooling conditions in the water cooling facility arranged between the exit side of the finishing mill and the winder, and the metal plate is wound up. When controlling the temperature to the target coiling temperature, a metal that calculates the temperature drop amount to achieve the target coiling temperature with a heat transfer model and adjusts the water cooling equipment to the cooling conditions according to the calculated temperature drop amount A cooling control method for a plate,
A metal plate cooling control method, wherein the temperature drop amount calculated in the next heat transfer model is corrected based on an error ratio or deviation between the temperature drop amount calculated in the heat transfer model and the actual temperature drop amount. . Between the finish rolling mill exit side to the winder, a water cooling zone and an air cooling zone are provided from the upstream side, and the water cooling equipment is arranged in the water cooling zone,
Based on at least the target winding temperature and the actual temperature at the finish rolling mill delivery side, the predicted temperature drop at the water cooling zone exit side is predicted using the heat transfer model, and the temperature drop calculated by the heat transfer model and the water cooling zone exit side are calculated. The metal plate cooling control method according to claim 2, wherein the temperature drop amount calculated in the next heat transfer model is corrected based on the actual temperature drop amount.   Based on at least the target winding temperature and the actual temperature on the delivery side of the finish rolling mill, predict the predicted temperature drop at the exit side of the water cooling zone and the exit side of the air cooling zone using the above heat transfer model, Correction based on the error ratio between the temperature drop at the side and the actual temperature drop at the water cooling zone outlet, and the temperature drop at the air cooling zone outlet and the actual temperature drop at the air cooling zone outlet calculated by the heat transfer model 4. The cooling control method for a metal plate according to claim 3, wherein a correction based on a deviation from the amount is applied to a temperature drop amount calculated by a next heat transfer model.   The said heat-transfer model uses the difference equation, The cooling control method of the metal plate of any one of Claims 2-4 characterized by the above-mentioned.

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