JP2001286916A - Method and device for controlling plate thickness in electrical screw-down type rolling mill - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a plate thickness control method in an electrical screw- down type rolling mill with which highly accurate thickness control is enabled using an electrical screw-down type where the accuracy of roll eccentricity is of a conventional degree. SOLUTION: By this thickness control method in the electrical screw-down type rolling mill, the average deviation ΔP1 of rolling load in the steady part of a bar 4 is measured in a preceding rolling mill (k-1), the amount ΔS of adjustment of roll gap of a controlled rolling mill k is calculated based on the ΔP1 and the roll gap of the controlled rolling mill k is adjusted by the ΔS. By this method, the bar is divided into plural sections, average thickness is calculated in the first half A of each section and, in accordance with the deviation between the average plate thickness and the target plate thickness, the plate thickness is controlled into the target plate thickness in the second half of the section. The non-steady part is controlled by a fixed pattern which is preset based on experience.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the thickness of a bar to be rolled in an electric rolling mill.

[0002]

2. Description of the Related Art BIS is the most typical sheet thickness control method.
RA AGC (British Iron & Steel Research Associa
tion auto gauge control. Also known as gauge meter AGC)
There is. This method regards the rolling mill as a kind of spring system,
In this method, the roll gap displacement caused by the change in the rolling reaction force (rolling load) is corrected by a roll rolling device and kept constant. The details will be described below. Assuming that the roll gap (roll gap) of the rolling mill is S and the rolling-out side plate thickness when the load during material rolling is P is h, h can be expressed by the following equation. h = S + P / K where K is the elastic modulus (mill constant) of the rolling mill. h derived from the above equation is called a gauge meter thickness, and the thickness during rolling can be immediately grasped. Used. However, since the gauge meter thickness is a calculated value from the rolling load and is basically different from the actual thickness, the product thickness is detected by the thickness gauge installed on the exit side of the rolling mill, and the control error is reduced. Correction is performed in a negative feedback manner by integral control. Basically, it is controlled as follows using a lock-on mechanism. The rolling load P _{0 in} regular rolling (rolling at the target thickness) and the set roll gap S ₀ when no load is applied,
The exit-side reference plate thickness h ₀ is set such servo mechanisms. When the setting of h ₀ is completed, this value is locked on. Accordingly, the sheet thickness deviation ε when the above value is locked on is as follows: ε = P ₀ / K + S ₀ −h ₀ = 0 The change in the outlet side sheet thickness after lock-on is completed is detected as a change in the rolling load. Assuming that the amount of change in the rolling load is ΔP ₁ , the thickness deviation ε is: ε = (P ₀ + ΔP ₁ ) / K + S ₀ −h ₀ = (P ₀ + ΔP ₁ ) / K + S ₀ − (P ₀ / K + S ₀ ) =
ΔP ₁ / K, and if the set roll gap is left as it is,
A sheet thickness deviation of ΔP ₁ / K occurs. Accordingly, assuming that the rolling screw is moved by ΔS to reduce the deviation ε to 0, and as a result, the rolling load changes by ΔP ₂ , ε = (P ₀ + ΔP ₁ + ΔP ₂ ) / K + S ₀ + ΔS−h ₀ = (ΔP ₁ + ΔP ₂ ) / K + ΔS = 0 Therefore, ΔS = − (ΔP ₁ + ΔP ₂ ) / K Then, the roll opening degree is adjusted so that the above equation is satisfied. That is, in the BISRA method, in the rolling stand, a change in the material to be rolled (incoming side plate thickness, deformation resistance) is captured as a change in rolling load, and dynamic control (control every moment) is performed. It is a highly applicable control method that can cope with any fluctuations, such as lack of reproducibility.

[0003]

However, the BISRA system has the following problems. Requires a hydraulic pressure reduction device. The BISRA method is a feedback control in which the rolling load at a location where rolling is currently performed is taken as information and the thickness of the gauge meter at this location is reduced to a predetermined value. Therefore, a high-speed response reduction device is required. Since the rolling device of a rolling mill for section steel is generally an electric rolling method with a slow response, BISRA-AG
In order to perform C, it is necessary to convert to a hydraulic pressure reduction method having a high-speed response, which increases equipment costs. Furthermore, even if it can be remodeled to the hydraulic pressure reduction method, the diameter of the roll used is restricted to the smaller diameter side due to the space in the rolling mill frame. Requires roll eccentricity measures. When the roll is eccentric (for example, when the outer periphery of the roll becomes elliptical with respect to the center of the roll), the roll gap (roll gap) becomes small at a portion where the roll diameter is large, and as a result, the exit side plate thickness becomes thin. And the rolling load increases. To correct this, the roll gap must be increased so as to increase the exit side plate thickness. However, BISRA-AGC recognizes that the increased rolling load is as if it were biting into the thicker part. However, in order to reduce the roll gap (to reduce the roll gap so as to reduce the gap), the thickness of the delivery side plate is further reduced. Thus, BISRA-A
In GC, if roll eccentricity exists, precise control cannot be performed, and therefore, high-precision roll cutting without eccentricity is required. In addition, it is necessary to newly install high-precision dedicated bearings, bearing boxes, and high-precision roll milling machines.In addition, dedicated equipment for assembling these tight-fitting bearings and rolls requires a great deal of man-hours. It costs. The object of the present invention is
To provide a method and apparatus for controlling a thickness in an electric rolling mill capable of obtaining a high-accuracy product thickness without changing the existing electric rolling method (without adding an additional hydraulic rolling device). It is in. Another object of the present invention is
An object of the present invention is to provide a sheet thickness control method and an apparatus for an electric screw-type rolling mill capable of obtaining a highly accurate product sheet thickness while maintaining the existing electric screw-down method with a roll eccentricity accuracy of a conventional level.

[0004]

The present invention to achieve the above object is as follows. (1) The rolling load average deviation of the steady portion of the bar to be rolled of the preceding rolling mill of the control rolling mill is measured, and the roll gap adjustment amount of the control rolling mill is calculated based on the load average deviation. The thickness control method in the electric rolling mill, wherein the roll gap of the control rolling mill is adjusted by the roll gap adjustment amount before the control roll is engaged with the control rolling mill. (2) Rolling load average deviation ΔP measured by the former rolling mill
_{From 1} , the roll gap adjustment amount ΔS in the control rolling mill is calculated as follows: ΔS = M ₀ ΔP ₁ / K ₁ K ₀ where M ₀ : material plasticity coefficient of the bar to be rolled (known) K ₁ : mill constant of the former stand ( known) K _0: the roll gap is calculated by mill modulus control stand (known) adjust ΔS min, in an electric reduction method rolling machine according to claim 1, wherein for controlling the thickness of the rolled bar to a target thickness Plate thickness control method. (3) A plurality of sections are set in the steady portion in the bar to be rolled, and an average value of the gauge meter plate thickness is obtained in the first half region for each section, and the average value of the gauge meter plate thickness is varied according to a deviation amount from a target value. A method for controlling the thickness of an electric rolling mill, wherein a rolling reduction of a control rolling mill is performed in a second half region of the section of the rolling bar so that a thickness of the rolling bar becomes a target thickness. (4) A threshold value is set for the deviation amount,
(3) The thickness control method for the electric rolling mill according to (3), wherein the thickness control in the latter half region of the section is performed only when the deviation amount exceeds the threshold value. (5) The method for controlling a thickness of an electric rolling mill according to (4), wherein the section is continuously moved. (6) The method according to (5), wherein another section shorter in length than the section is provided in the section. (7) The sheet thickness control method in the electric rolling mill according to (4), wherein the threshold value of the another section is set to be larger than the threshold value of the another section. (8) For the leading and trailing end unsteady portions of the bar to be rolled, the roll gap condition that can roll the unsteady portion to the target thickness is empirically determined, and the leading and trailing end unsteady portions of the bar to be rolled are fixed in the roll gap condition. A thickness control method in an electric rolling mill that rolls a part. (9) The bar to be rolled is controlled by the thickness control described in (1) and (3)
A thickness control method in an electric rolling mill, in which rolling is performed by arbitrarily combining the thickness control described in (8) and the thickness control described in (8). (10) A control rolling mill, a rolling mill including a preceding rolling mill immediately before the control rolling mill, an electric rolling device, a rolling position meter, a rolling load meter, and a calculation / control device provided in each rolling mill. becomes, the arithmetic and control unit, front rolling mill rolling force deviation undergoing rolling load signal calculates the constant region rolling load average value in the preceding stage rolling mill for calculating the bar rolling load difference [Delta] P ₁ from the preceding rolling mill A calculating means, a control rolling mill reduction correction amount calculating means for calculating a rolling correction amount (roll gap adjustment amount) of the control rolling mill, a control rolling mill reduction correction amount calculating means, and a signal from the control rolling mill reduction position meter. A sheet thickness control device for an electric rolling mill, comprising: a control rolling mill rolling control amount calculating means for receiving a reduction / release signal to an electric rolling device of a control rolling mill. (11) A control rolling mill, an electric rolling device, a rolling position meter, a rolling load meter, and a calculation / control device provided in the control rolling mill, and the calculation / control device is provided with a plurality of A section first half area gauge meter thickness average value calculating means for setting a section and calculating an average value of gauge meter thickness in a first half area for each section, and a gauge meter thickness average value in a second half area of each section being a target value. The control rolling mill reduction correction amount calculating means for adjusting the rolling reduction of the control rolling mill so that the control rolling mill reduction correction amount calculating means and the signal from the control rolling mill reduction position meter are controlled to control the reduction / release signals. A thickness control device for an electric rolling mill, comprising: a control rolling mill rolling control amount calculating unit that outputs to an electric rolling device of a rolling mill. (12) A control rolling mill, an electric rolling device, a rolling position meter, a rolling load meter, and a photoelectric tube provided in the control rolling mill,
A control device, wherein the arithmetic and control device comprises a control rolling mill rolling correction amount calculating means for selecting a control rolling mill rolling correction amount of a fixed pattern for the front and rear end unsteady portion regions of the bar; Control rolling mill reduction control which receives the signals from the control rolling mill reduction correction amount calculating means and the control rolling mill's rolling position meter when the end is detected, and outputs the rolling reduction / release signal to the electric rolling device of the control rolling mill. The thickness control device in the electric rolling mill according to (10) or (11), further comprising: an amount calculating unit.

[0005] With the above, the following operation and effects can be obtained. The sheet thickness control method in the electric rolling mill of the above (1) and (2) is control between bars (bars to be rolled) of a feedforward gap preset control system. In the sheet thickness control method, since the feed-forward control is performed, a highly accurate sheet thickness control can be performed even in an existing electric rolling mill having a slow response. In addition, the total length of the stationary part, or of a certain section,
Because of the control based on the rolling load average deviation, the minimum roll 1
By performing the control by averaging the thickness deviation of the rotation, control of the thickness deviation due to the roll deviation as in BISRA-AGC does not occur, and the roll cutting accuracy may be approximately the same as the conventional one. The method for controlling the thickness of the electric rolling mill of the above-mentioned (3) to (7) is control in a bar by a feedback system. In the thickness control method, the steady part is divided into several sections, and the gauge meter thickness is monitored in the first half of the section,
The rolling reduction is adjusted in the latter half of the section so that the average value of the gauge meter plate thickness becomes the target value. If the sheet thickness deviation is within a certain value, the rolling reduction need not be performed. Since this control is a section control method, it does not require high responsiveness as compared with direct control, and control suitable for an electric screw down device can be performed. Also,
In the first half of the section, since the average value of the gauge meter plate thickness is taken, the plate thickness deviation due to the roll deviation such as BISRA-AGC is controlled by averaging the plate thickness deviation for at least one rotation of the roll. There is no increase, and the roll cutting accuracy may be about the same as the conventional one. Further, by setting a threshold value so that the gap adjustment is not performed if the average value of the gauge meter plate thickness is within the threshold value, the load on the screw down device can be reduced. In the thickness control method for the electric rolling mill according to the above (8), since the unsteady portion is controlled to the target thickness in a fixed pattern according to the rolling conditions of each product, the yield due to the deviation of the thickness tolerance of the unsteady portion is obtained. Loss can be prevented. In the conventional AGC, it is impossible to control the unsteady portion, and the gauge is turned off and the waste treatment is performed. However, this can be solved. In the thickness control method for the electric rolling mill of (9), the bar to be rolled is arbitrarily combined with the thickness control of (1), the thickness control of (3), and the thickness control of (8). Since the rolling is performed, a further control effect can be obtained. Each of the above control methods can be executed by the sheet thickness control device in the electric rolling mill of the above (10), (11), and (12).

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for controlling a thickness of an electric rolling mill according to each embodiment of the present invention will be described. FIG.
The rolled material (i, i + 1, i + 2,...) Is divided into a plurality of bars 4 by a shear (shear) cutting machine 2 through extraction from a heating furnace 1, lumping / rough rolling, and a plurality of bars 4. Is formed by a rolling mill 3 (also referred to as a mill or a stand). In a rolling line of parallel mill arrangement, or in a rolling line in which continuous rolling cannot be performed even in a series mill arrangement, since the rolled material elongation length is limited by the distance between rolling mills,
After the slab rolling, it is sheared and sent to the subsequent rolling process. In this case, as the number of divisions increases, the temperature of the final shear material decreases, and the thickness and load increase, so that the average thickness deviation between the bars is large. The deviation generally consists of an inter-bar deviation and an intra-bar deviation. FIG. 2 shows a general graph of the bar thickness (in proportion to the load of the rolling mill) and time when the bar 4 of the first shear, the second shear, and the third shear is passed through a certain k-th rolling mill. It shows a simple relationship. In FIG. 2, the load fluctuates greatly at the front and rear ends of each bar.
This is due to the roll jumping up due to the biting impact at the front and rear ends, the unsteady rolling due to the free end, and the overcooling at the end. This portion is the unsteady portion. Other parts are stationary parts. The reason why the thickness and the load increase from the leading end to the trailing end in the steady portion of each bar is that the temperature of the bar decreases while passing through the rolling mill. The reason why the average load at the shear (i + 1) cut is higher than that at the shear i cut is that the temperature of the shear (i + 1) cut is lower than that at the shear i cut. The difference between the bar thicknesses (or rolling loads) between the bars 4 (the shear i-th cut and the shear (i + 1) cut) is the bar-to-bar deviation.
The change in the plate thickness (or rolling load) within (in the case of the share i cut only the share i cut) is the intra-bar deviation.
For any bar 4, this deviation approaches zero,
The thickness control of the present invention controls the thickness to the target thickness. The thickness control of the present invention is to control the thickness control by using an arithmetic and control unit (a personal computer or the like) in a conventional rolling mill of an electric drafting device without providing a hydraulic drafting device.

The method for controlling the thickness of the electric rolling mill according to the present invention generally comprises the following four controls. Bar thickness control using feedforward control Bar thickness control using feedback control Thickness control for unsteady part at the rear end of the bar Thickness control by any combination of the above control

First, as a first embodiment of the present invention, a method of bar-to-bar control (feed forward roll gap preset control) will be described with reference to FIG. The method of controlling the thickness of the electric rolling mill according to the first embodiment of the present invention is to measure the average deviation of the rolling load of the stationary portion of the bar 4 to be rolled in the first rolling mill (k-1) of the control rolling mill k. Before the rolling bar 4 bites into the control rolling mill k, the roll gap of the control rolling mill k is adjusted based on the load average deviation,
The average thickness of the bar 4 to be rolled is controlled to a target thickness by a feedforward method. That is, the method for controlling the thickness of the electric rolling mill according to the first embodiment uses the bar 4
From the entry side information (sheet thickness, deformation resistance) of the control rolling mill k (same as the exit side information of the pre-rolling mill (k-1)), the average length of the entire bar constant section or the section with the constant section is calculated. A method of calculating the roll gap adjustment amount ΔS of the control rolling mill k for controlling to the target thickness, and presetting the roll gap of the control rolling mill k before the bar 4 bites into the roll of the control rolling mill k. .

As shown in FIG. 3 (rolling state diagram), the roll gap adjustment amount ΔS can be obtained from the rolling load deviation ΔP ₁ of the former rolling mill (k−1) as follows. That is, the thickness deviation Δh on the entry side of the control rolling mill k.
₁ (entrance side plate thickness h ₁ -reference entry side plate thickness) is: Δh ₁ = ΔP ₁ / K ₁ where ΔP ₁ : rolling load P _{1 of the} preceding rolling mill (k−1)
- reference rolling load (measured value of the load cell of the preceding stage rolling mill) K _1: obtained by mill modulus of the preceding rolling mill (k-1) (known value). Rolling load deviation after thickness control ΔP ₀ = M ₀ Δh ₁ = M ₀ ΔP ₁ / K _{1 The} gap adjustment amount ΔS is ΔS = ΔP ₀ / K ₀ = M ₀ ΔP ₁ / K ₁ K ₀ where P ₀ : Rolling load of control rolling mill k (control rolling mill k
K ₀ : Mill constant of control rolling mill k M ₀ : Material plasticity coefficient (known value) under sheet thickness control conditions. Therefore, by adjusting the roll gap by ΔS, the outlet plate thickness of the control rolling mill k can be controlled to the target plate thickness.

[0010] For example, when the entry side plate thickness of the pre-rolling mill increases between bars (between the shear i cut and the share i + 1 cut), the measured load of the load cell of the pre-rolling mill increases by ΔP ₁ ,
The exit plate thickness of the former rolling mill increases by Δh ₁ . Since the exit side thickness of the pre-stage rolling mill is also the entrance side thickness of the control rolling mill k, the entrance side thickness of the control rolling mill k increases by Δh ₁ . The outgoing sheet thickness at the share i-th cut of the control rolling mill k is determined at the point a in FIG. 3 and is controlled to the target sheet thickness. When the entry side thickness of the mill k increases by Δh ₁ , the exit side thickness of the control rolling mill k at the (i + 1) th cut shifts to the point b in FIG. 3, so that a deviation occurs in the exit side thickness. Therefore, before the share i + 1 cut is engaged with the control rolling mill k, the roll gap is adjusted by ΔS with respect to the share i + 1 cut of the control rolling mill k, and the point b becomes the point c.
Move to. As a result, the exit side thickness of the control rolling mill k at the (share + 1) th cut is controlled to the target thickness (the thickness corresponding to the point c = the thickness at the point a). At this time, the load of the control rolling mill k is a load corresponding to the point c, so that P ₀ + Δ
P ₀ .

Next, as a second embodiment of the present invention, a method of in-bar control (gauge meter section plate pressure control) will be described with reference to FIGS. As shown in FIG. 4, the method of controlling the thickness of the electric rolling mill according to the second embodiment of the present invention employs a plurality of sections (A +
B) is set, and the average value of the gauge meter plate thickness (h = S + P / K) is obtained in the first half region A for each section, and according to the deviation amount between the average value of the gauge meter plate thickness and the target value (ie, In order to reduce the thickness of the rolled bar 4 to the target thickness), the control rolling mill is adjusted in the latter half region B of the section of the rolled bar 4 (feedback control). As shown in FIG. 4, the control is such that the roll gap is constant in section A (the operation section) and is linearly adjusted in section B (the operation section) (the gradient of gap versus time is linear). .

This section control system does not require high responsiveness as compared with the conventional general control system in which control is performed directly (a sharp control system in which the gap versus time changes in a saw-tooth shape). Control suitable for the characteristics of the device can be performed. The monitoring of the gauge meter plate thickness in the section A takes an average value, so that even if the roll is eccentric, it is not affected. In this case, a threshold value is provided for the target plate thickness value, and if the average value of the gauge meter plate thickness is within the threshold value, the roll gap adjustment is not performed in the latter half region B of the section to further reduce the roll-down device. The load can be reduced. Whether or not to provide this threshold value, and if so, how to set the width of the threshold value and the width of the section, depend on the thickness distribution characteristics of the rolled product, the required thickness accuracy, and the load of the rolling device. May be arbitrarily selected.

For example, as shown in FIG.
It may be as follows. Change the section from a fixed section to a continuous section. The gauge meter plate thickness average value for a certain length (time) section of the steady portion in the bar 4 is continuously calculated, and when the amount of deviation from the target value reaches a certain threshold value or more, pressure reduction control is performed. Control the thickness of the bar inside the bar. In this way, in the section of the gauge meter plate thickness average value fluctuation that does not reach the threshold value, it is possible to perform only the measurement and not to perform the plate thickness control. A shorter section is provided in the above-mentioned continuous section to control a sudden change in the thickness. The length of the continuous section is preferably long from the viewpoint of reducing the load on the electric screw-down device. But,
In this case, there is a possibility that a tolerance deviation may occur without being able to cope with a steep plate thickness variation. As a countermeasure for this, a section that is short enough to cope with the expected maximum thickness variation gradient is provided in the long section. Then, the threshold value for performing the rolling reduction is set smaller in a long section and larger in a short section. By doing so, it is possible to achieve both reduction of the load on the electric screw-down device and coping with sharp plate thickness fluctuation.

Next, as a third embodiment of the present invention, a method of controlling an unsteady portion will be described with reference to FIG. For each product size, the reduction of the fixed pattern is adjusted according to the plate thickness distribution gradient in the front-rear end unsteady portion region. The control method when combined with the inter-bar thickness control will be specifically described as an example. Regarding the control method of the leading end, the control roll gap between bars is calculated from the average rolling load deviation of the total length of the steady part in the preceding rolling mill, and the roll roll of the control rolling mill is calculated to a value that takes into account the rolling reduction of the unsteady part. A gap is set, and at the same time as the leading end of the bar to be rolled bites into the roll of the control rolling mill, the roll is released at a constant speed up to the control gap between the bars.
As for the control method of the rear end portion, the rolling reduction of the rear end unsteady portion is performed at a constant speed from the moment when the unsteady portion comes directly below the roll. Normally, the rear end has a lower temperature, so that the amount of reduction is increased due to a large reaction force. The unsteady part length of the rolled bar is
Know in advance empirically. The detection of the tip biting timing is possible by providing a trigger level in the rolling load measuring system (the moment when the actual rolling load value exceeds that level is the tip biting timing).
Alternatively, it is also possible to install a phototube immediately before the rolling mill and detect the phototube. The command of the rolling start timing of the rear end unsteady part is that a photoelectric tube is provided at the place where the end of the bar to be rolled is located when the rear end unsteady part comes directly below the roll, and the signal reception from the photoelectric tube is the rolling start timing Can be done with Naturally, the position of the phototube includes a correction for the response delay from the moment when the rolling end of the rolled material crosses the phototube to the start of rolling.

The method according to the fourth embodiment of the present invention comprises a thickness control method in which the above-described inter-bar control, intra-bar control, and unsteady portion control are arbitrarily combined. For example, as one combination method, the unsteady portion control of the fixed pattern is performed for the unsteady portion tip of the bar 4 to be rolled, and the bar-to-bar control is performed for a fixed section of the steady portion tip, The in-bar control is performed on the subsequent steady portion, and the unsteady portion control is performed on the rear end of the unsteady portion. As another combination method, there is a method in which bar-to-bar control and unsteady portion control are combined. As another combination method, there is a method in which the in-bar control and the unsteady portion control are combined. As another combination method, there is a method in which the unsteady portion control is removed and the control between bars and the control within a bar are combined. By arbitrarily combining the above control methods,
The control effect can be further improved in reducing the rolling mill load.

Next, a description will be given, with reference to FIGS. 7 and 8, of a sheet thickness control device in an electric rolling mill capable of performing the above-described methods. The plate thickness control device in the electric rolling mill according to the present invention is a rolling mill 3 including a control rolling mill k and a pre-stage rolling mill (k-1) immediately before the control rolling mill.
An electric rolling device 5, a rolling position gauge 6, a rolling load cell (for example, a load cell) 7, a photoelectric tube 10 installed in front of a control rolling mill k, and an arithmetic / control device 11 provided in each rolling mill 3. Consists of The rolling mill 3 has a pair of rolls 8 and 9. The gap between the rolls 8 and 9 is a roll gap, and the roll gap is adjusted by controlling the amount of reduction of the upper roll 8.

As shown in FIG. 7, the calculation / control device (for example, a personal computer) 11 is a bar-to-bar control calculation means 1.
2, a control calculation means 13 within the bar, a rolling pattern control means 14 for the unsteady portion, and a rolling control amount control 15 for the control rolling mill k. The means 12, 13, 14, 15 are means installed in the computer.

The inter-bar control calculating means 12 receives a rolling load signal from the pre-rolling mill (k-1) and receives the rolling load signal from the pre-rolling mill (k-1).
A front rolling mill rolling force deviation calculating means 121 for calculating the bar rolling load difference [Delta] P ₁ constant region rolling load average value (minimum roll one rotation) is calculated at -1), reduction correction amount of the controlled rolling machine k (Roll gap adjustment amount) Control rolling mill reduction amount calculation means 122 for calculating ΔS. The in-bar control calculating means 13 receives the rolling load signal and the rolling position signal in the first half of the section from the control rolling mill k, calculates the average value thereof, and calculates the thickness difference Δh, and calculates the thickness gauge Δh. And a control rolling mill rolling correction amount calculating means 132 for calculating a rolling reduction amount (roll gap adjustment amount) △ S of the control rolling mill k. Control amount control 15 for rolling mill k
Are inter-bar control calculation means 12 and intra-bar control calculation means 13
And the unsteady part rolling pattern control means 14 and the control rolling mill k
Receiving the signals from the rolling position meter 6 and the rolling load meter 7 and the photoelectric tube 10 installed at the entrance side of the control rolling mill k, and outputs a rolling-down / release signal to the electric rolling device 5 of the control rolling mill k. .

FIG. 8 shows one of the combinations of the thickness control methods.
Only bar thickness control between bars, a combination of bar-to-bar control and intra-bar control, a combination of bar-to-bar control, intra-bar control and unsteady portion control,
Is shown as an example. First, the control flow of only the bar thickness control between bars will be described with reference to the flow section 20 of FIG. In step 201, an initial value is input and set. The initial values include the rolling position of the control rolling mill, the mill constant of the control rolling mill, the material plasticity coefficient of the control rolling mill, and the target gauge meter plate thickness. Next, in step 202, a reference value is set. The reference value includes the rolling load of the former rolling mill, the rolling load of the control rolling mill, and the rolling position of the control rolling mill. Step 203
Start rolling with. In step 204, the rolling of the former rolling mill (k-1) is executed, and the rolling load of the former rolling mill (k-1) is read. In Step 205, the average value of the rolling load at the steady portion of the bar of the preceding rolling mill (k-1) (at least for one rotation of the roll) is calculated. Then step 2
06, the average rolling load deviation amount Δ of the preceding rolling mill (k-1)
To calculate the P _1. Steps 204, 205, 206
The rolling load deviation calculating means 121 of the first-stage rolling mill in FIG. 7 is configured. Next, in step 207, the reduction amount of the rolling position of the control rolling mill k (the gap adjustment amount ΔS of the control rolling mill k) is shown in FIG.
The calculation is performed by the method described above. Step 207 constitutes the control rolling mill reduction amount calculation means 122 of FIG.
Next, at step 208, a reduction / release command is output to the reduction device 5 of the control rolling mill k. Step 208 constitutes the rolling reduction control amount calculating means 15 of the control rolling mill k in FIG. Thereby, bar-to-bar control is executed. Then
In step 209, it is determined whether or not the rolling is completed. If the rolling is not completed, the process returns to the step 204 to execute the next bar-to-bar control. When the rolling is completed, the process proceeds from the step 209 to the END step, and the control calculation of the thickness is completed.

The combination of the inter-bar control and the intra-bar control will be described with reference to the flow section 30 in FIG. In addition, the control in a bar takes the case where a threshold value is provided. In step 301, an initial value is input and set. The initial values include the rolling position of the controlled rolling mill, the mill constant of the controlled rolling mill, the material plasticity coefficient of the controlled rolling mill, the target gauge meter plate thickness, and the control threshold value for control within the bar. Next, in step 302, a reference value is input and set. The reference value includes the rolling load of the former rolling mill, the rolling load of the control rolling mill, and the rolling position of the control rolling mill. In step 303, rolling is started. In step 304, the rolling of the former rolling mill (k-1) is performed, and the former rolling mill (k-1) is executed.
The rolling load at the tip of the steady portion is read. Step 30
In step 5, the average value of the rolling load (at least with respect to one rotation of the roll) at the tip of the steady portion of the bar of the preceding rolling mill (k-1) is calculated. Next, in Step 306, the pre-mill (k-1)
Of the average rolling load deviation ΔP ₁ at the end of the steady portion of the bar. Steps 304, 305, and 306 constitute the rolling load deviation calculating means 121 of the former rolling mill (k-1) in FIG. Next, in step 307, the reduction amount of the control rolling mill k (the gap adjustment amount ΔS of the control rolling mill k) is calculated by the method described with reference to FIG. Step 307 constitutes the control rolling mill rolling reduction amount calculating means 122 of FIG. Next, at step 308, a reduction / release command is output to the reduction device 5 of the control rolling mill k. Step 308 constitutes a part of the rolling control amount calculating means 15 of the control rolling mill k in FIG. As described above, the bar-to-bar control is executed. In step 309, first, in sub-step 3091, the rolling load and rolling position in the first half of the section where the bar is constant in the control rolling mill k are read. In sub-step 3092, the gauge meter thickness in the first half of the section where the bar is constant is calculated. The sub-step 3093 compares the average value of the gauge meter plate thickness with the control threshold value set as the initial value. If the gauge meter plate thickness average value is equal to or greater than the control threshold value, the deviation between the gauge meter plate thickness average value and the target value is determined in sub-step 3094, and the rolling position of the control rolling mill k in the latter half of a certain section is determined. And outputs a reduction / release command to the reduction device 5 of the control rolling mill k. Thereafter, step 3 is performed to control the next section.
Returning to step 091, control within the bar is continued. Next, it is determined in step 310 whether or not the rolling has been completed. If the rolling has not been completed, the process returns to step 304 to execute the next bar-to-bar control. When the rolling is completed, the process proceeds from step 310 to the END step, and the control calculation of the thickness is completed.

Finally, the combination of the inter-bar control, the intra-bar control, and the unsteady-portion control will be described with reference to the flow section 40 in FIG. still,
The control within the bar has been described in the case where a control threshold is provided. In step 401, an initial value is input and set. The initial values are the rolling position of the control rolling mill, the mill constant of the control rolling mill, the material plasticity coefficient of the control rolling mill, the target gauge meter plate thickness, the control threshold value for control in the bar, and the control threshold value for unsteady part control. Includes the length of the unsteady part and the amount of reduction at the leading and trailing ends. Next, in step 402, a reference value is input and set. The reference value includes the rolling load of the former rolling mill, the rolling load of the control rolling mill, and the rolling position of the control rolling mill. In step 403, rolling is started. In step 404, the rolling of the former rolling mill (k-1) is executed, and the rolling load at the tip of the steady part of the former rolling mill (k-1) is read. In step 405, the average value of the rolling load (at least the roll 1
Is calculated for the rotation. Then, step 406
In, calculates the bar constant region average rolling load deviation amount [Delta] P ₁ of the front end of the front rolling mill (k-1). Steps 404, 40
5, 406 constitute the rolling load deviation calculating means 121 of the pre-mill (k-1) of FIG. Then step 40
In 7, the rolling reduction amount of the control rolling mill k (the gap adjustment amount ΔS of the control rolling mill k) is calculated by the method described with reference to FIG. Step 407 constitutes the control rolling mill rolling reduction amount calculating means 122 of FIG. Then, in step 408,
The tip unsteady portion reduction amount set as an initial value is added to the reduction amount calculated in step 407, and the reduction value is output to the reduction device 5 of the control rolling mill k with the added value. Step 40
8 constitutes a part of the rolling control amount calculating means 15 of the control rolling mill k in FIG. As described above, part of the bar-to-bar control and the tip unsteady portion control are executed. In step 409, first, in sub-step 3091, the leading end of the rolled material is detected because the rolling load of the control rolling mill k fluctuates abruptly. A command is issued to the drafting device 5 of the control rolling mill k to release it to the drafting position calculated in step 407. As described above, the tip non-stationary part control is executed. Next, read the rolling load and rolling position of the first half of the tip section of the bar steady part,
In sub-step 3093, the average value of the gauge meter plate thickness in the first half of the section where the bar steady portion is located is calculated.
Calculates a comparison between the gauge meter plate thickness average value and the control threshold value set as the initial value. If the gauge meter plate thickness average value is equal to or larger than the control threshold value, the deviation between the gauge meter plate thickness average value and the target value is obtained in sub-step 3095, and
The rolling position of the control rolling mill k in the latter half of the tip section is calculated, and a rolling-down / release command is output to the rolling-down device 5 of the control rolling mill k.
Thereafter, the process returns to step 3093 to control the next section, and the control within the bar is continued. As described above, the in-bar control is executed. Sub-step 4096 during in-bar control
In the case where a signal indicating that the rear end unsteady portion of the rolled material has passed from the photoelectric tube is obtained from sub-step 4093 to sub-step 409
The subroutine 4097 is executed and the sub-step 4097 is executed. In sub-step 4097, the control rolling mill k is controlled so that the rear end unsteady portion rolling amount set in the initial value is sequentially added to the final rolling amount in the in-bar control during the rear end unsteady portion length set in the initial value. And outputs a pressure reduction / release command to the pressure reduction device 5. As described above, the rear end unsteady portion control is performed. Next, in step 410, it is determined whether or not the rolling is completed.
To execute the next bar-to-bar control. When the rolling is completed, proceed from step 410 to the END step,
The control calculation of the thickness is ended.

[0022]

According to the method for controlling the thickness of the electric rolling mill according to the first and second aspects of the present invention, since the feed-forward control is performed, high-precision sheet thickness control can be performed even in an existing electric rolling mill having a slow response. it can. In addition, for control based on the rolling load average deviation of the entire length of the steady portion or a certain section, the control is performed by averaging the thickness deviation of at least one rotation of the roll, thereby performing control such as BISRA-AGC. The thickness deviation due to the roll deviation is not promoted, and the roll cutting accuracy is equivalent to the conventional level. According to the sheet thickness control method in the electric rolling mill according to claims 3 to 7, the section control method does not require high responsiveness as compared with direct control, so that control suitable for the electric rolling device can be performed. . In the first half of the section, the average value of the gauge meter plate thickness is taken, so the BISRA-A
There is no increase in sheet thickness deviation due to roll deviation as in the case of GC, and roll cutting accuracy may be on the order of the conventional art. Further, by setting a threshold value so that the gap adjustment is not performed if the average value of the gauge meter plate thickness is within the threshold value, the load on the screw down device can be reduced. According to the sheet thickness control method in the electric rolling mill according to claim 8, the unsteady part is controlled to the target sheet thickness in a fixed pattern according to the rolling conditions of each product. Yield loss can be prevented. Conventionally, the unsteady portion is discarded as waste, but can be used in the present invention. According to the sheet thickness control method in the electric rolling mill according to claim 9, rolling is performed by arbitrarily combining the inter-bar thickness control, the inner bar thickness control, and the unsteady portion thickness control. Can be measured. According to the plate thickness control device for the electric rolling mill of the tenth to twelfth aspects, each of the above control methods can be executed.

[Brief description of the drawings]

FIG. 1 is a plan view of a rolling line.

FIG. 2 is a graph showing the relationship between the plate thickness / time of shear 1, 2, and 3 cuts in a rolling mill having a rolling line.

FIG. 3 is a rolling state diagram of a feed-forward system bar-to-bar control theory of the first embodiment of the present invention.

FIG. 4 is a graph showing a concept of a fixed section and a relationship between a sheet thickness and a set roll gap versus a material length (time) to be rolled in a control within a feedback bar according to a second embodiment of the present invention.

FIG. 5 is a graph showing a relationship between a section of bar section control and a threshold.

FIG. 6 is a graph showing the relationship between the sheet thickness and the set roll gap versus the length (time) of the material to be rolled in the unsteady portion control of the third embodiment of the present invention.

FIG. 7 is a system diagram of a sheet thickness control device in the electric rolling mill according to the present invention.

FIG. 8 is a flowchart in a control combination example of the present invention.

[Explanation of symbols]

Reference Signs List 3 rolling mill k control rolling mill k-1 pre-rolling mill 4 bar to be rolled (simply referred to as bar) 5 electric rolling device 6 rolling position meter 7 rolling load meter 8, 9 roll 10 photoelectric tube 11 arithmetic and control device (for example, PC) 12 Inter-bar control calculation means 121 Rolling load deviation calculation means of the preceding control rolling mill 122 Control rolling mill reduction amount calculation means 13 In-bar control calculation means 131 Discharge gauge meter plate thickness deviation calculation means of control rolling mill 132 Rolling correction amount calculating means of a control rolling mill 14 Unsteady part rolling pattern control means 15 Rolling control amount calculating means of a control rolling mill 20 Flow section only for bar-to-bar control 30 Flow section for combination of bar-to-bar control and intra-bar control 40 Flow part of inter-bar control, intra-bar control and unsteady part control combination

Claims (12)

[Claims] 1. A method of measuring a rolling load average deviation of a stationary portion of a bar to be rolled of a preceding rolling mill of a control rolling mill, calculating a roll gap adjustment amount of the control rolling mill based on the load average deviation, and A sheet thickness control method in an electric rolling mill, wherein a roll gap of a control rolling mill is adjusted by the roll gap adjustment amount before a rolling bar bites into the control rolling mill. 2. A roll gap adjustment amount ΔS in a control rolling mill from an average rolling load deviation ΔP ₁ measured in a preceding rolling mill.
ΔS = M ₀ ΔP ₁ / K ₁ K ₀ where M ₀ : material plasticity coefficient of the bar to be rolled (known) K ₁ : mill constant of the preceding stand (known) K ₀ : mill constant of the control stand (known) 2. The method according to claim 1, wherein the roll gap is adjusted by .DELTA.S to control the thickness of the bar to be rolled to the target thickness. 3. A plurality of sections are set in a steady portion in the rolled bar, and an average value of the gauge meter plate thickness is obtained in the first half region for each section, and a deviation amount of the average value of the gauge meter plate thickness from a target value. And controlling a rolling mill in a second half region of the section of the bar to be rolled, so that the thickness of the bar to be rolled becomes a target thickness. 4. The apparatus according to claim 3, wherein a threshold value is set for the deviation amount, and only when the deviation amount exceeds the threshold value is the thickness control of the latter half region of the section performed. Thickness control method in the electric rolling method rolling mill. 5. The method according to claim 4, wherein the section is continuously moved. 6. The method according to claim 5, wherein another section having a shorter length than the section is provided in the section. 7. The method according to claim 4, wherein a threshold value of said another section is set to be larger than a threshold value of said section. 8. The leading and trailing end unsteady portions of the bar to be rolled are determined empirically to determine the roll gap conditions that allow the unsteady portion to be rolled to a target thickness, A method for controlling the thickness of an electric rolling mill in which an unsteady part is rolled. 9. An electric rolling mill for rolling a bar to be rolled by arbitrarily combining the thickness control according to claim 1, the thickness control according to claim 3, and the thickness control according to claim 8. Thickness control method. 10. A rolling mill including a control rolling mill, a pre-stage rolling mill immediately before the control rolling mill, an electric rolling device, a rolling position meter, a rolling load meter provided in each rolling mill, and an operation / control device. The arithmetic and control unit receives the rolling load signal from the preceding rolling mill, calculates the steady-state rolling load average value in the preceding rolling mill, and calculates the bar-to-bar rolling load deviation ΔP.
Pre-rolling mill rolling load deviation calculating means for calculating ₁ ; control rolling mill rolling correction amount calculating means for calculating rolling reduction amount (roll gap adjustment amount) of the control rolling mill; control rolling mill rolling correction amount calculating means and control Control rolling mill reduction control amount calculating means for receiving a signal from a rolling position gauge of a rolling mill and outputting a signal of reduction and release to an electric rolling reduction device of a control rolling mill, and a plate in an electric rolling type rolling mill. Thickness control device. 11. A control rolling mill, comprising: an electric rolling device, a rolling position meter, a rolling load meter provided in the control rolling mill, and a calculation and control device, wherein the calculation and control device is provided in a steady portion in the bar. A section first half area gauge meter thickness average value calculating means for setting a plurality of sections and calculating an average value of the gauge meter thickness in the first half area for each section; and a gauge meter thickness average value in the second half area of each section. Control rolling mill reduction correction amount calculation means for adjusting the rolling reduction of the control rolling mill to the target value, control rolling mill reduction correction amount calculation means, and reduction and release signals in response to signals from the control rolling mill reduction position meter And a control rolling mill control amount calculating means for outputting the control value to the electric rolling device of the control rolling mill. 12. A control rolling mill, comprising: an electric rolling device, a rolling position meter, a rolling load meter, a photoelectric tube, and an arithmetic and control device provided in the control rolling mill, and the arithmetic and control device includes: Control rolling mill reduction correction amount calculation means for selecting a fixed pattern control rolling mill reduction correction amount for the end non-stationary part region, and control rolling mill reduction correction amount calculation means and control rolling when the photoelectric tube detects the front and rear ends of the bar 12. A control rolling mill reduction control amount calculating means for receiving a signal from a rolling position gauge of a rolling mill and outputting a rolling reduction / release signal to an electric rolling reduction device of a control rolling mill. Thickness control device in an electric draft rolling mill.