CN118555990A - Plate thickness control device for rolling mill - Google Patents

Abstract

A plate thickness control device of a rolling mill that rolls a rolled material to a target product plate thickness includes a plate thickness deviation learning unit and a gap correction amount calculation unit. The plate thickness deviation learning unit learns the difference between the product plate thickness and the actual plate thickness of the rolled material measured at the exit side of the rolling mill, that is, the tendency of the plate thickness deviation. In addition, the plate thickness deviation learning unit sets the rolled material to be rolled by the rolling mill as the rolled material, and before rolling the rolled material, predicts the plate thickness deviation of the rolled material based on product information including the product plate thickness and steel type of the rolled material and the measured value of the rolled material measured at the upstream side of the rolling mill. The gap correction amount calculation unit calculates the gap correction amount for correcting the roll gap of the rolling mill to eliminate the plate thickness deviation predicted by the plate thickness deviation learning unit. The plate thickness control device of the rolling mill adjusts the roll gap of the rolling mill based on the gap correction amount calculated by the gap correction amount calculation unit before rolling the rolled material.

Description

Plate thickness control device for rolling mill

Technical Field

The present disclosure relates to a plate thickness control device for a rolling mill, and more particularly, to a plate thickness control device for a tandem rolling mill having a plurality of stands.

Background Art

For example, in a hot rolling process, the gap between the upper and lower working rolls of a rolling mill (hereinafter referred to as "roll gap") is appropriately operated by a press-down device, thereby controlling the thickness of the rolled material to the product thickness (set thickness). As such control, monitoring AGC (Automatic Gauge Control) and absolute value AGC are known.

The monitoring AGC is a feedback control based on the measured value of the plate thickness gauge installed behind the rolling mill in the conveying direction of the rolled material. The monitoring AGC has the advantage of being able to use the plate thickness measured value with high reliability as the measured value. On the other hand, the monitoring AGC generates a delay in the measurement of the plate thickness gauge installed behind the rolling mill and a delay in the control, so it is difficult to eliminate the plate thickness deviation (deviation between the product plate thickness and the actual plate thickness) at the front end of the rolled material.

Absolute value AGC is a feedback control that uses the mill exit thickness predicted (estimated) by the instrument expression based on the measured value of the load generated during rolling and the roll gap. Absolute value AGC can reduce the delay in control because it can use the rolling load and roll gap without measuring delay. On the other hand, if the prediction accuracy of the plate thickness is low, it will become the main cause of the plate thickness fluctuation.

However, immediately after rolling begins, the measured values used in the plate thickness control are unstable. Therefore, it is difficult to accurately control the plate thickness of the front end of the rolled material. For example, the temperature of the front end of the rolled material varies greatly, and it is difficult to suppress the plate thickness deviation caused by the temperature change through the plate thickness control. As a result, the product plate thickness deviates from the tolerance, resulting in a decrease in the yield rate.

Patent Document 1 below discloses a method for manufacturing a hot rolled plate as a rolled material. In this method, a plate thickness map of the front end portion of the hot rolled plate is recorded in advance according to the steel type and plate thickness. Then, a plate thickness map of the same steel type and plate thickness as the hot rolled plate to be rolled is read out, and the roll gap is adjusted in consideration of the read plate thickness map and tolerance, thereby shortening the plate thickness deviation length of the front end portion, and as a result, achieving an improvement in the yield rate.

Furthermore, an automatic thickness control method for a rolling mill is disclosed in the following Patent Document 2. This method is a feed-forward AGC that corrects the roll gap based on a measurement value of a thickness gauge installed at the entry side of the rolling mill.

Prior art literature

Patent Literature

Patent Document 1: Japanese Patent Application Publication No. 2013-198920

Patent Document 2: Japanese Patent Application Laid-Open No. 1-154814

Summary of the invention

Problems to be solved by the invention

However, in Patent Document 1, the main causes of plate thickness deviation are limited to steel type and plate thickness, and therefore, the plate thickness deviation that may be caused by other main causes cannot be suppressed. In addition, in Patent Document 2, it is not possible to cope with the case where a plate thickness gauge is not provided at the entry side of the rolling mill. In the case of a tandem rolling mill, it is known that the plate thickness measured by the plate thickness gauge at the entry side of the rolling mill has little effect on suppressing the plate thickness deviation.

The present disclosure has been made to solve the above-mentioned problems, and its object is to provide a plate thickness control device for a rolling mill that can improve the plate thickness accuracy by suppressing the plate thickness deviation that may be caused by the main causes of the plate thickness deviation other than the steel type and the plate thickness.

Means for solving problems

The first viewpoint relates to a plate thickness control device of a rolling mill that rolls a rolled material to a target product plate thickness. The plate thickness control device includes a plate thickness deviation learning unit and a gap correction amount calculation unit. The plate thickness deviation learning unit learns the difference between the product plate thickness and the actual plate thickness of the rolled material measured at the exit side of the rolling mill, that is, the tendency of the plate thickness deviation. In addition, the plate thickness deviation learning unit sets the rolled material to be rolled by the rolling mill as the rolled material, and before rolling the rolled material, predicts the plate thickness deviation of the rolled material based on product information including the product plate thickness and steel type of the rolled material and the measured value of the rolled material measured at the upstream side of the rolling mill. The gap correction amount calculation unit calculates the gap correction amount for correcting the roll gap of the rolling mill to eliminate the plate thickness deviation predicted by the plate thickness deviation learning unit. The plate thickness control device of the rolling mill adjusts the roll gap of the rolling mill based on the gap correction amount calculated by the gap correction amount calculation unit before rolling the rolled material.

The second aspect is based on the first aspect and has the following characteristics: The measured value of the rolled material is the temperature of the rolled material measured on the upstream side of the rolling mill.

The third aspect has the following features in addition to the first aspect or the second aspect: The thickness deviation learning unit learns a learning thickness deviation obtained by adding a predicted thickness deviation of the rolled material to an actual thickness deviation obtained from an actual thickness of the rolled material.

The fourth aspect is characterized in that, in addition to the first aspect or the second aspect, the rolling mill further comprises a plate thickness deviation average calculation unit that calculates an average value of the plate thickness deviation of the front end portion of the rolled material predicted by the plate thickness deviation learning unit, and a gap correction amount calculation unit that calculates a gap correction amount to eliminate the average value calculated by the plate thickness deviation average calculation unit.

Effects of the Invention

In the first aspect, the following configuration is adopted: using a plate thickness deviation learning unit, the plate thickness deviation is predicted based on not only the product plate thickness and steel type but also the measured value on the upstream side of the rolling mill, and the roll gap of the rolling mill is adjusted to eliminate the predicted plate thickness deviation, so that the plate thickness deviation that may be generated due to the main cause of the plate thickness deviation other than the product plate thickness and steel type can be suppressed. As a result, the plate thickness accuracy of the rolled material can be improved.

According to the second aspect, by predicting the thickness variation of the rolled material in consideration of the temperature of the rolled material measured on the upstream side of the rolling mill, it is possible to suppress the thickness variation caused by the temperature as a factor of the thickness variation.

According to the third aspect, the learning value of the thickness deviation learning unit is updated based on the learning thickness deviation, so the prediction accuracy of the thickness deviation by the thickness deviation learning unit can be improved, thereby further improving the thickness accuracy of the rolled material.

According to the fourth aspect, the yield rate of the front end portion of the rolled material can be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram for explaining the system configuration of a rolling facility.

FIG. 2 is a schematic diagram showing the configuration of the plate thickness control device for the rolling mill according to the first embodiment.

FIG. 3 is a diagram showing an example of the hardware configuration of a process control computer that implements the plate thickness control device.

FIG. 4 is a diagram showing an example of calculation of the amount of change in the rolling reduction rate of each stand.

FIG. 5 is a schematic diagram showing the configuration of a plate thickness control device for a rolling mill according to a second embodiment.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same reference numerals are given to common elements in each figure, and repeated descriptions are omitted.

Implementation method 1.

Fig. 1 is a schematic diagram showing the structure of a rolling mill 1. The rolling mill 1 uses steel or other metal materials as a rolled material M and hot-rolls the rolled material M into a plate shape.

The rolling equipment 1 is provided with a heating furnace 2, a roughing mill 3, a shearing mill 4, a finishing mill 5 as a hot rolling mill, a cooling device 6, and a coiler 7 as main equipment. In this embodiment, the case where the plate thickness at the exit side of the finishing mill 5 as a hot rolling mill is controlled to be the product plate thickness (for example, 3.0 mm) is described as an example.

The heating furnace 2 is configured to heat the slab M, which is a rolled material M before rolling, to a predetermined temperature. The heating temperature is, for example, 1200° C. The slab at the exit of the heating furnace 2 is, for example, a rectangular parallelepiped with a thickness of 200 to 250 mm, a width of 800 to 2000 mm, and a length of 5 to 12 m.

The rough rolling mill 3 has at least one, usually one to three rolling stands, and is configured to perform multiple passes of rolling in the forward direction (direction from the upstream side of the rolling line to the downstream side) and the reverse direction (direction from the downstream side of the rolling line to the upstream side) on the rolled material M heated by the heating furnace 2. A width adjustment device called an edger (not shown) may be attached to the rough rolling mill 3.

The shearing machine 4 is configured to cut off a shape defective portion existing at a leading end or a trailing end of the rolled material M using upper and lower blades based on a shape measured by a shape detector 81 described later.

The finishing mill 5 is equivalent to the rolling mill of the present embodiment. The finishing mill 5 is a tandem rolling mill having a plurality of rolling stands (hereinafter referred to as "stands") Fi (1≤i≤N) arranged side by side in the conveying direction of the rolled material M. i is the stand number. In the present embodiment, the case where N=7, that is, the case where 7 stands F1 to F7 are arranged side by side is described as an example. Each stand F1 to F7 is respectively equipped with two upper and lower working rolls 51, two upper and lower support rolls 52, and a motor 53 for roller rotation. A pressing device 54 is provided on the support roll 52, and is configured to be able to adjust the roll gap between the upper and lower working rolls 51 by the pressing device 54. The rolling load of each stand F1 to F7 is measured by a rolling load sensor 55. The rolling load sensor 55 is, for example, a force sensor. In addition, the roll gap of each rolling stand F1 to F7 can be measured by a magnetic scale not shown in the figure.

The cooling device 6 is provided on a run-out table (not shown). The cooling device 6 is configured to cool the rolled material M by pouring water through a cooling bed. The rolled material M after cooling is wound into a coil by a coiler 7.

Various sensors serving as various measuring devices are provided at important positions of the rolling equipment 1. Important parts of the rolling equipment 1 are, for example, the exit side of the heating furnace 2, the exit side of the roughing mill 3, the exit side of the finishing mill 5, and the entry side of the coiler 7. Various sensors may also be provided between the stands F1 to F7 of the finishing mill 5. The various sensors include a shape detector 81 capable of measuring the shape (including the plate width) of the rolled material M at the exit side of the roughing mill 3, a thermometer 82 for measuring the surface temperature of the rolled material M at the upstream side of the finishing mill 5, a plate thickness gauge 83 for measuring the actual plate thickness of the rolled material M at the exit side of the finishing mill 5, and the above-mentioned rolling load sensor 55 for measuring the rolling load of each stand F1 to F7. The various sensors sequentially measure the state of the rolled material M and each device.

The rolling equipment 1 is operated by a control system using a computer. The computer includes a host computer 10 and a process control computer 11 which are interconnected via a network. The host computer 10 calculates a plate thickness plan for realizing the product plate thickness of the rolled material M. The calculated plate thickness plan includes the plate thickness at the exit side of each stand Fi. The host computer 10 further calculates the roll gap of each stand Fi for realizing the plate thickness at the exit side of each stand Fi. The calculated roll gap of each stand Fi is input as a setting calculation to the plate thickness control unit 113 described later. An interface screen 12 serving as an operation screen for an operator is connected to the process control computer 11 via a network. The operator can perform input operations for control conditions on the interface screen 12, etc.

The process control computer 11 performs a series of calculations and controls for setting the control objects in the rolling process. In addition, the process control computer 11 has the function of correcting the roll gaps of each stand F1 to F7. Product information is input from the host computer 10 to the process control computer 11. The product information includes target information (product target) such as product plate thickness and product plate width of the rolled material M after being heated by the heating furnace 2, and the steel type.

The process control computer 11 appropriately controls each device based on the target information and the control conditions provided from the interface screen 12. When conveying the rolled material M to the specified position of the rolling equipment 1, the process control computer 11 calculates the settings of each device that can achieve the target information, and operates the actuators of each device based on these setting values. During the operation of each device, the action of the actuator is corrected according to the values obtained from various measuring instruments. The process control computer 11 adjusts the roll gap of each stand F1 to F7 of the finishing mill 5 according to the rolling load and the actual plate thickness so that the actual plate thickness of the rolled material M becomes the product plate thickness (that is, the plate thickness deviation is eliminated).

2 is a schematic diagram showing the configuration of a process control computer 11 as a plate thickness control device for a rolling mill according to Embodiment 1. The process control computer 11 includes a plate thickness deviation learning unit 111 , a gap correction amount calculation unit 112 , and a plate thickness control unit 113 .

The plate thickness deviation learning unit 111 learns the difference between the actual plate thickness measured by the plate thickness meter 83 on the outlet side of the finishing mill 5 and the product plate thickness, that is, the tendency of the plate thickness deviation after rolling. The plate thickness deviation is learned based on the product information and the measured value (correlated) measured on the upstream side of the finishing mill 5. The product information includes, for example, at least the product plate thickness and steel type, and may also include the product width. The measured value is a main cause of the plate thickness deviation other than the steel type and the plate thickness, for example, at least includes the temperature of the rolled material M measured by the thermometer 82 on the inlet side of the finishing mill 5 (hereinafter also referred to as the "finishing rolling inlet temperature"), and may also include the plate width of the rolled material M measured by the shape detector 81 on the inlet side of the finishing mill 5. In addition, as the plate thickness deviation for learning after rolling, a value obtained by adding the plate thickness deviation per 1m predicted by the plate thickness deviation learning unit 111 before rolling to the actual plate thickness deviation calculated based on the actual plate thickness of the corresponding position of the rolled material M measured by the plate thickness meter 83 can be used. The learning accuracy is improved by updating the learning value each time the rolled material M is rolled. By constructing the plate thickness deviation learning unit 111 by a neural network described later, online learning can be performed.

The plate thickness deviation learning unit 111 predicts the plate thickness deviation of each specified length (for example, 1 m) before rolling the rolled material M (hereinafter also referred to as "the rolled material M") to be rolled by the finishing mill 5 through a machine learning function. As a machine learning function, for example, the above-mentioned neural network can be used. In this case, the input layer can be set to items related to the plate thickness deviation, such as product plate thickness, product width, finishing rolling inlet temperature, and rolling distance, and the output layer can be set to the predicted plate thickness deviation of the rolled material M (hereinafter also referred to as "predicted plate thickness deviation").

The gap correction amount calculation unit 112 has a function of calculating the correction amount of the roll gap to eliminate the predicted thickness deviation of the rolled material M predicted by the thickness deviation learning unit 111. The gap correction amount calculation unit 112 first calculates the thickness correction amount based on the roll gap correction. The thickness correction amount is calculated based on the change in the reduction rate of each stand Fi based on the outlet side thickness of each stand Fi in the thickness plan calculated by the host computer 10. The reduction rate is defined by the following formula (1).

【Mathematical formula 1】

Here, i represents the stand number, _ri represents the rolling reduction rate of each stand Fi, and _hi represents the exit thickness of each stand Fi in the thickness plan. The amount of change in the rolling reduction rate is represented by the following formula (2).

【Mathematical formula 2】

Here, _Δri represents the change in the reduction ratio of the stand Fi, and _Δhi represents the thickness correction amount of the stand Fi. In addition, when the total number of stands is N (N=7 in this embodiment), the thickness correction amount _ΔhN of the final stand FN (F7 in this embodiment) represents the predicted thickness deviation.

However, when the plate thickness correction amount Δh _N of the final stand FN is significantly greater than the plate thickness correction amounts of other stands (F1 to F6 in this embodiment), that is, when the plate thickness is sharply reduced in the final stand FN, a notch may be generated between the final stand FN and the stand F(N-1) on its upstream side. In this case, even if a notch machine is provided, the notch cannot be controlled, which impairs the stability of rolling.

Therefore, the gap correction amount calculation unit 112 calculates the plate thickness correction amount _Δhi of each stand Fi so as to satisfy the following relational expression (3).

【Mathematical formula 3】

Here, ξ _i represents the ratio of the change in the reduction ratio of the stand Fi, and a preset arbitrary value greater than 0 is provided as each ratio ξ _i . For example, when the ratio ξ ₁ of the stand F1 is set to 2 and the ratio ξ ₄ of the stand F4 is set to 1, it means that the change amount Δr ₁ of the reduction ratio of the stand F1 is set to twice the change amount Δr ₄ of the reduction ratio of the stand F4. In addition, if the ratios ξ ₁ to ξ ₇ of all the stands F1 to F7 are set to the same value, the change amount of the reduction ratio of all the stands F1 to F7 can be made the same. In this way, by setting the ratio ξ _i provided to each stand Fi, the plate thickness can be gradually reduced in each stand F1 to F7, and the stability of rolling can be improved.

FIG3 is a diagram showing an example of calculation of the reduction ratio and the reduction ratio change of each stand Fi. The calculation conditions are as follows: the total number of stands is set to 7, the product plate thickness is set to 3 mm, and the predicted plate thickness deviation is set to 0.1 mm. In addition, the ratio ξ ₁ to ξ ₃ of the front-stage stands F1 to F3 is set to 2, and the ratio ξ ₄ to ξ ₇ of the rear-stage stands F4 to F7 is set to 1. As a result, the change in the reduction ratio of the front-stage stands F1 to F3 with relatively high rolling stability is made higher (twice) than the change in the reduction ratio of the rear-stage stands F4 to F7 with relatively low rolling stability, further improving the rolling stability.

The gap correction amount calculation unit 112 calculates the thickness correction amount Δhi for each 1m of the thickness deviation predicted by the thickness deviation learning unit ₁₁₁ , and then uses the target thickness correction amount _Δhi for each stand Fi calculated for each 1m to calculate the gap correction amount ΔScomp _,i for each stand Fi using the following equation (4) called an instrument expression, and outputs it to the finishing mill 5.

【Mathematical formula 4】

Here, M _i represents a rolling constant, and Q _i represents a plasticity coefficient, which are calculated by setting calculation of the host computer 10 .

The gap correction amount ΔS _comp,i is used to adjust the roll gap of each stand Fi according to the rolling distance of each stand Fi. In addition, in the present embodiment, the gap correction amount ΔS _comp,i is calculated every 1 m based on the length of the outlet side of the finishing mill 5, but in consideration of the length change of the rolled material M in each stand Fi, the roll gap of each stand Fi is adjusted based on the conversion from the length reference of the outlet side of the finishing mill 5 to the length reference of the outlet side of each stand Fi.

The plate thickness control unit 113 has the following functions: based on the setting calculation input from the host computer 10, the roll gap of each stand Fi is controlled, thereby controlling the plate thickness at the exit side of each stand Fi. Before rolling, the control signal output from the plate thickness control unit 113 is added to the gap correction amount ΔS _comp,i output from the gap correction amount calculation unit 112, and the added control signal is respectively input to the press device 54 of each stand Fi of the finishing mill 5. Thus, before rolling, the roll gap of each stand Fi is adjusted. When rolling starts, the plate thickness control unit 113 performs feedback control on the roll gap of each rolling stand Fi based on the actual plate thickness input from the plate thickness meter 83.

The specific structure of the process control computer 11 is not limited, but as an example, it can also be configured as follows. FIG. 4 is a diagram showing an example of the hardware structure of the process control computer 11. The function of the process control computer 11 can be realized by the processing circuit shown in FIG. 4. The processing circuit can also be dedicated hardware 20a. The processing circuit can also include a processor 20b and a memory 20c. The processing circuit can also be partially formed as dedicated hardware 20a, and also include a processor 20b and a memory 20c. In the example of FIG. 4, a part of the processing circuit is formed as dedicated hardware 20a, and the processing circuit also includes a processor 20b and a memory 20c.

At least a part of the processing circuit may be at least one dedicated hardware 20a. In this case, the processing circuit corresponds to, for example, a single circuit, a complex circuit, a programmed processor, a parallel programmed processor, an ASIC, an FPGA, or a combination thereof.

The processing circuit may also include at least one processor 20b and at least one memory 20c. In this case, each function of the process control computer 11 is implemented by software, firmware, or a combination of software and firmware. Software and firmware are described as programs and stored in the memory 20c. The processor 20b reads out the program stored in the memory 20c and executes it, thereby realizing the functions of each part.

The processor 20b is also called a CPU (Central Processing Unit), a central processing unit, a processing unit, an arithmetic unit, a microprocessor, a microcomputer, or a DSP. The memory 20c is, for example, a nonvolatile or volatile semiconductor memory such as a RAM, a ROM, a flash memory, an EPROM, or an EEPROM.

In this way, the processing circuit can realize the functions of the process control computer 11 through hardware, software, firmware or a combination thereof.

Next, a description will be given of a method for controlling the thickness of the finishing mill 5 performed by the process control computer 11 .

Before rolling the rolled material M, when the process control computer 11 receives input from the host computer 10, the plate thickness deviation learning unit 111 predicts the plate thickness deviation of the rolled material M by the machine learning function, and outputs the predicted plate thickness deviation to the gap correction amount calculation unit 112. The gap correction amount calculation unit 112 calculates the gap correction amount ΔS _comp,i to eliminate the predicted plate thickness deviation of the rolled material M. As described above, the gap correction amount calculation unit 112 calculates the plate thickness correction amount Δh _i of the rolled material M, calculates the gap correction amount ΔS _comp,i using the plate thickness correction amount Δh _i , and outputs the calculated gap correction amount ΔS _comp,i to the finishing mill 5. In addition, the plate thickness control unit 113 outputs the setting calculation input from the host computer 10, that is, the roll gap setting value of each stand Fi to the finishing mill 5. A signal obtained by adding the gap correction amount ΔS _comp,i output from the gap correction amount calculation unit 112 to the roll gap setting value output from the plate thickness control unit 113 is input to the finishing mill 5. In the finishing mill 5, the roll gap is adjusted by the press-down device 54 of each stand Fi according to the input signal. In this way, the roll gap of each stand Fi is adjusted in a feed-forward manner before the rolling of the rolled material M. Then, the rolling of the rolled material is started, and when the actual plate thickness is input from the plate thickness gauge 83 to the plate thickness control unit 113, the plate thickness control unit 113 performs feedback control.

After the rolling of the rolled material M, the process control computer 11 obtains the difference between the actual plate thickness measured by the plate thickness meter 83 and the predicted product plate thickness, i.e., the actual plate thickness deviation, and adds the predicted plate thickness deviation predicted by the plate thickness deviation learning unit 111 to obtain the learning plate thickness deviation. The plate thickness deviation learning unit 111 learns the obtained learning plate thickness deviation, thereby updating the learning value of the plate thickness deviation learning unit 111. At this time, it is performed in association with the product plate thickness, product width, and finish rolling entry temperature.

According to the present embodiment, the following configuration is adopted: before rolling, the plate thickness deviation learning unit 111 is used to predict the plate thickness deviation based not only on the product plate thickness and steel type but also on the temperature of the rolled material M measured on the upstream side of the finishing mill 5, and the roll gap of each stand Fi of the finishing mill 5 is adjusted to eliminate the predicted plate thickness deviation. Therefore, the plate thickness deviation that may be generated due to the main cause of the plate thickness deviation other than the product plate thickness and steel type can be suppressed. As a result, the plate thickness accuracy of the rolled material M can be improved.

Furthermore, the plate thickness deviation learning unit 111 learns the plate thickness deviation for learning, thereby improving the prediction accuracy of the plate thickness deviation by the plate thickness deviation learning unit 111, thereby further improving the plate thickness accuracy of the rolled material M.

Implementation method 2.

5 is a schematic diagram showing the configuration of a plate thickness control device for a rolling mill according to Embodiment 2. Embodiment 2 is different from Embodiment 1 in that a plate thickness deviation average calculation unit 114 and a gap setting calculation unit 115 are provided. In addition, in Embodiment 2, portions overlapping with those in Embodiment 1 are not mentioned.

The plate thickness deviation average calculation unit 114 calculates the average value of the plate thickness deviation at the front end of the rolled material M among the plate thickness deviations predicted by the plate thickness deviation learning unit 111 before rolling the rolled material M. The front end is set, for example, in a range where the temperature measured by the thermometer 82 is relatively unstable, that is, a range where the accuracy of plate thickness control per 1m is relatively low, for example, in a length range of 5m to 10m from the front end of the rolled material M.

The gap correction amount calculation unit 112 calculates the gap correction amount ΔS _comp,i based on the thickness deviation average value calculated by the thickness deviation average calculation unit 114. The calculation of the gap correction amount ΔS _comp,i is the same as in the first embodiment, and the above formula (4) can be used.

The gap setting calculation unit 115 calculates the set value of the roll gap of each stand Fi of the finishing mill 5 before rolling the rolled material M. The set value of the roll gap calculated by the gap setting calculation unit 115 is corrected by adding the gap correction amount ΔS _comp,i calculated by the gap correction amount calculation unit 112, and the corrected set value is input to the finishing mill 5. Based on the corrected set value, the roll gap of each stand Fi is adjusted before rolling the rolled material M.

According to the present embodiment, the plate thickness controllability of the front end portion of the rolled material M is improved, so that the yield of the front end portion can be improved. In addition, the gap setting calculation unit 115 provided in the process control computer 11 calculates the set value of the roll gap and corrects the calculated set value, thereby reliably adjusting the roll gap of each stand Fi before rolling the rolled material M.

In addition, regarding the plate thickness control at and after the front end of the rolled material M, the above-mentioned first embodiment can be used in combination.

The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments, and various modifications can be made and implemented within the scope of the main purpose of the present invention. When the number, quantity, amount, range, etc. of each element in the above embodiments are mentioned, the present invention is not limited to the mentioned quantity except for the case where it is specifically stated and the case where it is clearly specified as the quantity in principle. In addition, the structure described in the above embodiments is not necessarily required in the present invention except for the case where it is specifically stated and the case where it is clearly specified as the quantity in principle.

Explanation of symbols:

5: finishing mill (rolling mill); 11: plate thickness control device, process control computer; 111: plate thickness deviation learning unit; 112: gap correction amount calculation unit; M: rolled material.

Claims (4)

1. A plate thickness control device for a rolling mill for rolling a rolled material to a target product plate thickness, comprising:

A sheet thickness deviation learning unit that learns a tendency of sheet thickness deviation, which is a difference between the product sheet thickness and the actual sheet thickness of the rolled material measured on the exit side of the rolling mill, and predicts the sheet thickness deviation of the rolled material based on product information including the product sheet thickness and the steel grade of the rolled material and measured values of the rolled material measured on the upstream side of the rolling mill before rolling the rolled material, by setting the rolled material to be rolled by the rolling mill as the rolled material; and

A gap correction amount calculation unit for calculating a gap correction amount for correcting a roll gap of the rolling mill so as to eliminate the plate thickness deviation predicted by the plate thickness deviation learning unit,

Before rolling the rolled material, the roll gap of the rolling mill is adjusted based on the gap correction amount calculated by the gap correction amount calculating unit.

2. The plate thickness control device for rolling mill according to claim 1, wherein,

The measured value of the rolled material is a temperature of the rolled material measured on an upstream side of the rolling mill.

3. A plate thickness control device for a rolling mill according to claim 1 or 2, wherein,

The plate thickness deviation learning unit learns, after rolling of the rolled material, a learning plate thickness deviation obtained by adding an actual plate thickness deviation obtained from the actual plate thickness of the rolled material to the plate thickness deviation of the rolled material predicted before rolling of the rolled material.

4. A plate thickness control device for a rolling mill according to claim 1 or 2, wherein,

The plate thickness control device of the rolling mill further comprises a plate thickness deviation average calculating unit for calculating an average value of the plate thickness deviation of the front end portion of the rolled material predicted by the plate thickness deviation learning unit before rolling the rolled material,

The gap correction amount calculating unit calculates the gap correction amount before rolling the rolled material so as to eliminate the average value calculated by the plate thickness deviation average calculating unit.