JPH0257443B2 - - Google Patents

Description

[Detailed description of the invention] (Technical field) The present invention relates to a method for controlling plate thickness in a rolling mill,
In particular, the present invention relates to a method for suppressing variations in plate thickness due to roll eccentricity of a rolling mill and improving plate thickness accuracy.

(Prior art and its problems) Conventionally, a predetermined material to be rolled is passed between the rolls of a roll stand of a rolling mill to continuously roll the material to a desired thickness. The process of manufacturing is adopted, but
In such a rolling process, roll eccentricity of the rolling stand, for example, in the case of a four-high rolling mill, roll eccentricity caused by misalignment of the rotation center and axis of the back-up roll placed behind the work roll. Due to the eccentricity, the pressure applied to the work roll changes, resulting in the thickness of the rolled material varying as the roll rotates.

By the way, the relationship between such roll eccentricity and rolling load fluctuation is expressed by the following formula (1): ΔS _E =-(M+Q)/MQΔP _E ...(1) [However, ΔS _E : Rolling load fluctuation due to roll eccentricity ΔS _E : The amount of change in roll gap due to roll eccentricity M: Mill constant Q: Plasticity coefficient] Conventionally, the first
As shown in the outline in Fig. b, when rolling the material 2 to be rolled in a four-high rolling mill consisting of work rolls 4, 4 and back-up rolls 6, 6, the rolling load is applied. Load cell 8
Then, from the detected rolling load fluctuation, the rolling load fluctuation component due to roll eccentricity is determined by Fourier analysis, etc., and then, according to equation (1) above, the amount of roll gap change due to roll eccentricity (ΔS _E ), and then operate the rolling device 10 installed in the rolling mill so as to cancel it, thereby changing the amount of rolling.

However, in the roll eccentricity control method based on such a method, the load (ΔP _LC ) detected by the load cell 8 is used to estimate the roll gap change amount due to roll eccentricity. Control performance largely depends on load detection accuracy, and if the detection accuracy is poor, the accuracy of eccentricity control cannot be improved, resulting in the problem that plate thickness fluctuations cannot be sufficiently suppressed.

Moreover, in this conventional method, it is necessary to know the plasticity coefficient Q of the plate material 2 to be rolled before rolling, but since this plasticity coefficient differs for each material 2, all of the material 2 to be rolled is It is extremely troublesome work to obtain the plasticity coefficient for each of the above factors, and it is therefore extremely difficult to accurately give the plasticity coefficient Q. Therefore, the amount of roll gap change due to roll eccentricity (ΔS _E ) It was difficult to determine accurately.

On the other hand, in Japanese Patent Publication No. 54-35986, the rolling speed,
An automatic plate thickness control device has been disclosed that uses a correlation function generator to determine the roll gap change due to roll eccentricity from the plate thickness and load signals, and operates the rolling device to cancel it. However, thickness control methods using such devices use correlation function generators that require a large amount of calculations, making calculations complicated.
Furthermore, since sequential calculations cannot be performed, it is difficult to shorten the control period, making it unsuitable for highly accurate plate thickness control.

(Solution Means) Here, in view of the conventional problems as described above, the present inventor has conducted various studies, and as a result, the relationship between roll eccentricity, rolling load, and plate thickness change is as follows.
Equation (2): ΔS _E = Δh _E −ΔP _E /M ...(2) [However, Δh _E : Amount of plate thickness change due to roll eccentricity ΔS _E : Amount of roll gap change due to roll eccentricity ΔP _E : Rolling load due to roll eccentricity Variation M: Mill constant] Based on the basic idea of using equation (2), this was completed by controlling roll eccentricity and, by extension, controlling plate thickness. .

That is, the present invention allows a predetermined material to be rolled to pass between the rolls of a rolling mill, and when the material to be rolled is continuously rolled, changes in rolling load due to roll eccentricity are detected by a load cell, while The change in thickness of the material to be rolled due to roll eccentricity on the exit side of the machine is detected by a plate thickness gauge, and the amount of change in roll gap due to roll eccentricity is calculated based on equations (7) to (9) described later, and then canceled. A method for controlling plate thickness in a rolling mill is characterized in that the plate thickness is controlled by operating a rolling device to change the amount of rolling.

(Function) In short, in the present invention, as is clear from the schematic diagram shown in Fig. 1a, the load fluctuation (ΔP _LC ) detected by the load cell 8 and the The roll eccentricity component is determined from the plate thickness change amount ( _Δh (7) which will be explained later
The amount of roll gap change (ΔS _E ) due to roll eccentricity is calculated according to equation (9), and the rolling device 10 is operated to cancel it, thereby changing the amount of rolling in the rolling mill, thereby controlling the plate thickness. As a result, load accuracy becomes less of an issue, and there is no longer any need to determine the plasticity coefficient in advance.

(Specific Description/Examples) By the way, based on the basic concept according to the present invention, a compensator for suppressing plate thickness variation due to roll eccentricity of a rolling mill and improving plate thickness accuracy is as follows:
Specifically, it will be designed as follows.

First, in order to extract the component of the roll eccentric period from the rolling load, the back-up roll 6 is divided into I parts as shown in FIG. Considering that each position is taken out as i (i=1, 2,
3...I), the controlled object is expressed by the following equations (3) and (4)
It will be expressed as

Δh(i)=ΔS _c (i)+ΔP(i)/M+ΔS _E (i) ……(3) Δh _x (i)=Δh(i−τ) ……(4) Note that each symbol in the above equation The meaning is as follows.

Δh(i): Change in plate thickness on exit side ΔS _c (i): Reduction control system output (roll gap instruction value) ΔP(i): Change in rolling load ΔS _E (i): Amount of change in roll gap due to roll eccentricity Δh _x (i): Thickness gauge output (thickness deviation) M: Mill constant τ: Delay due to distance between the thickness gauge and the roll directly below The rolling control system model can be expressed as follows.

ΔS _c (i) = K・ΔU _s (i-m) ...(5) However, ΔU _s (i): Gap change command K: Down control system gain m: Delay of the down control system The formula means that when a roll gap change command is given, the actual roll gap will be delayed by a distance m and will be multiplied by K.

Since the roll eccentricity is a periodic function whose period is one rotation of the roll, it can be further expressed as in the following equation (6).

ΔS _E (n×I+i)=ΔS _E [(n-1)×I+i]
...(6) (However, n represents the number of rotations of the roll) Therefore, if an observer is configured to estimate the amount of change in roll gap due to roll eccentricity from equations (3) and (6) above, the following (7) is obtained. It becomes as shown in equation (9).

ΔS^ _E (n×I+i−τ)=ΔS^ _E [(n−1)×I+
i−τ]+k・(y−y^)……(7) y=Δh _x [(n−1)×I+i]……(8) y^=ΔS _c [(n−1)×I+i−τ ]+ΔP[(n-1
)×I+i−τ]/M+ΔS^ _E [(n−1)×I+i−
τ]...(9) [However, ΔS^ _E (i): Estimated value of roll gap change amount due to roll eccentricity y-y^: Estimation error of roll gap change amount due to roll eccentricity k: Observer gain] In addition, this estimated value Roll gap change amount:
The gap change command to compensate for ΔS^ _E (i) can be expressed as follows from equation (5).

ΔU _s (n×I+i)=-1/KΔS^ _E [(n-1)×
I+i+m]...(10) In short, the above equations (7) to (9) are the method for estimating the roll gap change amount due to roll eccentricity, and the equation (10) is the method for giving the gap change command based on the estimated value. By calculating the amount of change in roll gap due to roll eccentricity based on these formulas, and then operating the rolling down device to change the amount of rolling down to cancel it, plate thickness fluctuations due to roll eccentricity can be effectively suppressed. Therefore, the plate thickness accuracy can be advantageously improved.

The specific configuration (system) of roll eccentricity control according to the present invention is shown in FIG. 8, the load fluctuation (ΔP) is outputted, divided by a mill constant (M) predetermined by the rolling mill, and then guided to the delay device 14. This delay device 14 also contains the amount of roll reduction in the roll reduction device 10 when giving such ΔP, that is, the roll reduction control system output (roll gap instruction value: ΔS _c ).
is input at the same time to compensate for the delay in the plate thickness change amount (-Δh _x ) at the roll position output from the plate thickness meter 12 disposed on the exit side of the rolling mill.

Then, after those outputs are multiplied by the observer gain (k), ΔS^ _E (estimated roll gap change amount due to roll eccentricity) is stored in table 1.
6, the amount of roll gap change due to roll eccentricity is estimated according to the known observer theory, and based on the estimated value, a gap change command is input to the operation control device 18 of the lowering device 10. , and based on this input, the operation control device 18 causes the lowering device 1 to
By changing the amount of reduction by 0, the rolling mill is controlled so that the target thickness is achieved.

Further, FIG. 4 shows an example of the simulation results according to the method according to the present invention, in which a is the amount of change in roll gap due to roll eccentricity, b is an estimated amount of change in roll gap due to roll eccentricity, and c is the exit side plate. The state of thickness change is shown. In addition, this simulation assumes that the detected value of the rolling load is 80% of the actual value, and even in such a case, the roll eccentricity estimation is performed accurately, and the exit plate thickness due to roll eccentricity is It is understood that change is 100% suppressed.

The present invention is not limited to the above specific description in any way, and various changes, modifications, improvements, etc. can be made based on the knowledge of those skilled in the art without departing from the spirit of the present invention. Something should be understood.

(Effects of the Invention) As is clear from the above explanation, the present invention calculates the amount of change in roll gap due to roll eccentricity based on the above equations (7) to (9). Compared to methods such as those that calculate only from the rolling load, the accuracy of load detection decreases because it uses two pieces of information: the rolling load and the plate thickness.
Even if the load (ΔP) becomes 0, it is possible to calculate the amount of roll gap change due to a certain degree of roll eccentricity based on the plate thickness information, and therefore load detection accuracy will not be as much of a problem as with conventional methods. Moreover, since the plasticity coefficient of the material is not required, it is possible to effectively suppress plate thickness fluctuations due to roll eccentricity of the rolling mill, and thereby advantageously improve plate thickness accuracy. It became possible to improve the situation. In addition, in the present invention,
The amount of roll gap change due to roll eccentricity is
Since it is estimated according to equations (7) to (9), there is no need to use a correlation function generator that requires a large amount of calculation, and it can be easily implemented using a general-purpose computer. is possible, and sequential calculations can be performed at the same time as plate thickness and load signals are detected.
Compared to the conventional method using a correlation function generator, it is possible to shorten the control period, and therefore, it is possible to perform more precise control.

[Brief explanation of the drawing]

FIGS. 1a and 1b are schematic diagrams illustrating roll eccentricity control according to the present invention method and a conventional method, respectively, and FIG. 2 is an explanatory diagram for explaining the roll division format in a rolling mill. , Figure 3 is
FIG. 4 is a system diagram showing a specific configuration of the roll eccentricity control method according to the present invention, and FIG. 4 is a graph showing simulation results according to the method according to the present invention, where a is the amount of roll gap change due to roll eccentricity, and b is due to roll eccentricity. The roll gap change estimation amount, c, indicates the exit side plate thickness change. 2: Rolled plate material, 4: Work roll, 6: Backup roll, 8: Load cell, 10: Rolling device, 12: Plate thickness gauge, 14: Delay device, 16: ΔS^ _E
Memory table, 18: Actuation control device.

Claims (1)

[Scope of Claims] 1. When a predetermined material to be rolled is passed between the rolls of a rolling mill and the material to be rolled is continuously rolled, fluctuations in rolling load due to roll eccentricity are detected by a load cell; The plate thickness change due to roll eccentricity of the rolled material on the exit side of the rolling mill is detected using a plate thickness gauge, and the following formula: ΔS^ _E (n×I+i−τ) =ΔS^ _E [(n−1)×I+i −τ]+k・(y−
y^) y=Δh _x [(n-1)×I+i] y^=ΔS _c [(n-1)×I+i-τ] +ΔP[(n-1)×I+i-τ]/M +ΔS^ _E [ (n-1)×I+i-τ] However, ΔS^ _E (i): Estimated value of roll gap change due to roll eccentricity y-y^: Estimated error of roll gap change due to roll eccentricity k: Observer gain ΔS _c (i ): Rolling control system output (roll gap indication value) ΔP(i): Rolling load change Δh _x (i): Plate thickness gauge output (plate thickness deviation) M: Mill constant n: Roll rotation speed I: Number of roll position information i: Roll position τ: Calculate the amount of roll gap change due to roll eccentricity based on the delay due to the distance directly below the roll and the plate thickness gauge, and then operate the rolling device to change the rolling amount to cancel it out, and calculate the plate thickness. 1. A method for controlling plate thickness in a rolling mill, characterized by controlling the thickness of a rolling mill.