JP5553340B2 - Skin pass mill control method - Google Patents

Description

  The present invention relates to a method for controlling a skin pass mill that performs temper rolling of a steel sheet by rolling down a roll with a hydraulic servo.

  The skin pass mill normally controls the position based on the deviation between the position command value and the actual position value by the position sensor that detects the roll position during non-rolling, and detects the load command value and the load on the steel plate during rolling. The load control is performed based on the deviation from the actual load value by the load sensor. And at the time of rolling start, if a roll is rolled down by position control, roll kissing and a control switching load (for example, 50t) is reached, it will switch from position control to load control.

  Hereinafter, a conventional control method will be described in detail with reference to FIG. The skin pass mill shown in the figure includes a pair of upper and lower work rolls 1a and 1b and upper and lower backup rolls 2a and 2b, and is provided with a hydraulic servo valve 3 on each of the operation side (WS) and the drive side (DS). The roll is crushed by the valve 3 via the hydraulic cylinder 4 on each of the operation side and the drive side, and the temper rolling of the steel sheet S is performed.

  The lower backup roll 2b is provided with a position sensor 5 for detecting the position of the roll on each of the operation side and the drive side, and using the actual position value of the roll detected by the position sensor 5, the operation side and the drive side The position control circuit 6 performs position control.

  The upper backup roll 2a is provided with a load sensor 7 (load cell) for detecting the load on the steel sheet S on each of the operation side and the drive side, and the actual load value on the steel sheet S detected by the load sensor 7 is used. Thus, the load control circuit 8 performs load control on each of the operation side and the drive side.

  Since the position control circuit 6 and the load control circuit 8 on the driving side are the same as the position control circuit 6 and the load control circuit 8 on the operation side, the details are omitted in FIG.

  The position control circuit 6 performs a proportional operation (proportional gain Kp) by the proportional amplifier 6 a based on the deviation between the position command value and the actual roll position value detected by the position sensor 5, thereby opening the hydraulic servo valve 3. Output the value.

  The load control circuit 8 performs a proportional operation (proportional gain Kp) by the proportional amplifier 8a based on the deviation between the load command value and the actual load value to the steel sheet S detected by the load sensor 7, and performs an integral operation by the integrator 8b. (Integral gain Ki) is performed, and the opening command value of the hydraulic servo valve 3 is output. In this load control circuit 8, the load command value is issued from the rate generator 8c.

  In the above configuration, at the start of rolling, roll reduction is started by position control with the switch S1 being set to the position control side. After that, when the load sensor 7 detects that the actual load value on the steel sheet S has reached the control switching load (for example, 50 t) by roll kissing, the switch S1 is switched from the position control to the load control. At the start of load control, the load control circuit 8 turns on the switch S2 and turns off the switch S3, inputs the control switching load as an initial value of the rate generator 8c, and immediately uses it as a load command value. .

  The control operation at the time of this control switching is as follows, and a conceptual image thereof is shown in FIG. In FIG. 4, solid lines indicate command values for position, load, and hydraulic servo valve opening, and broken lines indicate actual values of position and load.

  Hereinafter, events from “control switching” to “arrival of set load” in FIG. 4 will be described with reference to FIG.

(1) Immediately before switching from position control to load control, the opening command value (for example, 10%) of the hydraulic servo valve 3 for maintaining the current roll position is output from the position control circuit 6 to the hydraulic servo valve 3. ing.
(2) Immediately after switching from position control to load control, the opening command value of the hydraulic servo valve 3 of the load control circuit 8 starts from 0%, and the opening of the hydraulic servo valve 3 instantaneously drops to 0%.
(3) Since the opening degree of the hydraulic servo valve 3 instantaneously returns to 0%, the actual load value detected by the load sensor 7 rapidly decreases.
(4) As a result of the abrupt decrease in the actual load value, the integrator 8b of the load control circuit 8 starts accumulating the deviation, rapidly increasing the stored value, and rapidly increasing the opening command value of the hydraulic servo valve 3. .
(5) When the actual load value reaches the load command value, the stored value of the integrator exceeds the value that maintains the load command value due to a rapid increase, and the opening command value of the hydraulic servo valve 3 has a required opening. The actual load value overshoots.
(6) When the actual load value exceeds the load command value, the integrator 8b of the load control circuit 8 decreases the stored value.
(7) The above increase / decrease is repeated and the overshoot amount is attenuated, and the load actual value eventually coincides with the load command value.
(8) When the load fluctuation is settled, the switch S2 is turned off and the switch S3 is turned on. Then, the rate generator 8c increases the load command value at a constant rate toward a set load (for example, 500 t), and starts operation at the set load.

  Thus, in the conventional control method, when the actual load value on the steel sheet S reaches the control switching load, the control circuit is switched from the position control circuit 6 to the load control circuit 8, and thus the position control circuit 6 has output until then. When the opening command value for the hydraulic servo valve 3 is switched to the load control circuit 8, the load once starts from zero, and it has been forced to generate some load fluctuation until the control is stabilized.

  If the load is increased to the set load when the load is not sufficiently stable, the steel plate may be squeezed, and once the squeezing occurs, the squeezing may not be canceled, which may cause a considerable defect. There is. Therefore, conventionally, in order to stabilize this load fluctuation, after the load is temporarily held by the control switching load (about 0.1 to 1 s), the load is increased to the set load after confirming the stability of the load. I took. However, even with this method, in the case of a thin plate that has a small rolling load and is prone to squeezing, there is a problem that initial load fluctuations may cause squeezing, and it is further set by the holding time described above. There was a problem that the time to reach the load was increased and the defective rolling part was increased by this holding time.

  On the other hand, in Patent Document 1, when switching from position control to pressure (load) control or from pressure (load) control to position control, between dynamic position information and position target information, and dynamic pressure information and pressure target information. A control method has been proposed in which the above-described switching is performed smoothly by initially controlling the rolling operation unit based on the correlation of deviations between the two. However, as described below, the control method of Patent Document 1 cannot actually control the skin pass mill.

  The control method of Patent Document 1 will be described with reference to FIG. Since the configuration on the skin path side to be controlled is the same as that in FIG. 3, the same components as those in FIG. 3 are denoted by the same reference numerals and description thereof is omitted.

  In the control method of Patent Document 1, a control circuit 11 including a position control circuit A and a load control circuit B shown in FIG. 5 is used. The case where the control circuit 11 performs the same operation as described above is as follows.

  First, roll reduction starts with position control. Thereafter, when the actual load value on the steel sheet S reaches the control switching load (for example, 50 t) by roll kissing, the initial correction value 11b is calculated and stored, and the switch S4 is set on the load control side by the position / load switching operation unit 11c. The switch S5 is turned off, the switch S6 is turned on, and the initial correction value 11b is set in the load control circuit B.

At the time immediately before switching from position control to load control, the opening command value of the hydraulic servo valve 3 for maintaining the current roll position is output from the position control circuit A to the hydraulic servo valve 3. The opening command value of the hydraulic servo valve 3 at this time is “K ₁ · e ′ _l ”.

On the other hand, the load control side circuit B, and outputs the deviation _{e p} between the set load _{r P} (e.g. 500t) load actual value (e.g., 50t).

The output of the initial correction value 11b is output by the following calculation.
11b output = e _P − (K ₁ / K ₂ ) · e ′ _l

As a result, the opening command value of the hydraulic servo valve 3 of the load control circuit B is as follows.
Opening command value = {e _P − {e _P − (K ₁ / K ₂ ) · e ′ _l }} · K ₂ = K ₁ · e ′ _l

This “K ₁ · e ′ _l ” coincides with the opening command value of the hydraulic servo valve 3 output by the position control circuit A immediately before switching to the load control, and the value output by the position control circuit A is the same. It will be taken over.

As a result, no load fluctuation occurs at the time of switching. However, it is not possible to obtain a set load r _P, the load after switching remains load carried over at the time of switching (e.g. 50t), does not reach the set load r _{P (e.g.,} 500t). Then, Changing the set load _{r P} (e.g. 600t), since the initial correction value 11b is always given as an offset, the load actual value (e.g. 150t) is not able to match the set load _{r P.}

Further, when thereafter removing the initial correction value 11b, the control circuit 11 operates to match the set load r _P, removing it becomes a disturbance was, impair the stability of the control. That is, in the control method of Patent Document 1, the initial correction value 11b stores a load deviation at the time of switching (for example, 450 t) and subtracts it from the output, so that load fluctuation at the time of switching does not occur. but cause offset its initial correction value, when to switch in the control algorithm, with the defect that it can not reach the set load r _P.

Japanese Utility Model Publication No. 5-13604

  The problem to be solved by the present invention is that, in the control of the skin pass mill, at the start of rolling, the load fluctuation does not occur when switching from the position control to the load control, and the skin pass mill can smoothly reach the set load. It is to provide a control method.

  The control method of the present invention is a control method of a skin pass mill that performs temper rolling of a steel sheet by rolling down a roll with a hydraulic servo. During non-rolling, the position command value and the actual position of the roll detected by a position sensor Based on the deviation from the value, the position control circuit performs position control to output the opening command value of the hydraulic servo valve, and during rolling, the deviation between the load command value and the actual load value on the steel plate detected by the load sensor Based on this, when the load control circuit performs load control that performs proportional and integral operations to output the opening command value of the hydraulic servo valve, and switches from position control to load control, the steel plate detected by the load sensor at the time of switching Is the initial load command value for load control, and the opening command value of the hydraulic servovalve output from the position control circuit is the integral gain of the integrator that performs the integral operation in the load control circuit. It is characterized in that to store the value as the initial value of the integrator.

  The “hydraulic servo” mentioned above refers to a control system including a hydraulic servo valve, a sensor, and a control circuit.

  According to the control method of the present invention, when switching from position control to load control, the opening of the hydraulic servo valve at the start of load control is the same as the opening of the hydraulic servo valve at the end of position control. There is no need to worry about the generation, and the holding with the control switching load becomes unnecessary.

  In the conventional control method shown in FIG. 3, since load fluctuation occurs when switching from position control to load control, it is necessary to hold at the control switching load to stabilize it, and the rolling load In the case of a thin plate that is small and easily generates a restriction, there is a possibility that the restriction will be generated due to a load fluctuation caused by a control switching load.

  In the control method of the present invention, as described above, there is no possibility of causing load fluctuations, and it is not necessary to hold with control switching load, so there is no possibility of occurrence of throttling due to load fluctuation at the time of switching. Therefore, it is possible to shorten the length of the defective rolling section.

  In addition, unlike the control method of Patent Document 1, the control method of the present invention does not cause an offset to the set load when switching to load control. After switching to load control, the set load is output through a rate generator. By doing so, the load command value can be increased at a constant rate, and the set load can be reached smoothly.

The structure of the control circuit which performs the control method of this invention is shown. The conceptual image of the control operation | movement by the control method of this invention is shown. The structure of the control circuit which performs the conventional control method is shown. The conceptual image of the control action by the conventional control method of FIG. 3 is shown. The structure of the control circuit which performs the control method of patent document 1 is shown.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 shows the configuration of a control circuit that executes the control method of the present invention.

  The skin pass mill shown in the figure is the same as that shown in FIG. 3, and includes a pair of upper and lower work rolls 1a and 1b and upper and lower backup rolls 2a and 2b, respectively, on the operation side (WS) and the drive side (DS). The hydraulic servo valve 3 is provided, and the roll is crushed by the hydraulic servo valve 3 via the hydraulic cylinder 4 on each of the operation side and the drive side, and the temper rolling of the steel sheet S is performed.

  The lower backup roll 2b is provided with a position sensor 5 for detecting the position of the roll on each of the operation side and the drive side, and using the actual position value of the roll detected by the position sensor 5, the operation side and the drive side The position control circuit 6 performs position control.

  The upper backup roll 2a is provided with a load sensor 7 (load cell) for detecting the load on the steel sheet S on each of the operation side and the drive side, and the actual load value on the steel sheet S detected by the load sensor 7 is used. Thus, the load control circuit 8 performs load control on each of the operation side and the drive side.

  Since the position control circuit 6 and the load control circuit 8 on the driving side are the same as the position control circuit 6 and the load control circuit 8 on the operation side, details thereof are omitted in FIG.

  The position control circuit 6 performs a proportional operation (proportional gain Kp) by the proportional amplifier 6 a based on the deviation between the position command value and the actual roll position value detected by the position sensor 5, thereby opening the hydraulic servo valve 3. Output the value.

  The load control circuit 8 performs a proportional operation (proportional gain Kp) by the proportional amplifier 8a based on the deviation between the load command value and the actual load value to the steel sheet S detected by the load sensor 7, and performs an integral operation by the integrator 8b. (Integral gain Ki) is performed, and the opening command value of the hydraulic servo valve 3 is output. In this load control circuit 8, the load command value is issued from the rate generator 8c.

  In the above configuration, at the start of rolling, roll reduction is started by position control with the switch S1 being set to the position control side. After that, when the load sensor 7 detects that the actual load value on the steel sheet S has reached the control switching load (for example, 50 t) by roll kissing, the switch S1 is switched from the position control to the load control. At this time, by turning on the switch S2 and turning off the switch S3, the actual load value to the steel sheet S detected by the load sensor 7 at the time of switching is input as the initial value of the rate generator 8c, and the actual load value is input. A value obtained by dividing the opening command value of the servo valve output from the position control circuit 6 by the integral gain (Ki) of the integrator 8b is set as the initial value of the integrator 8b. Remember.

  The control operation at the time of this control switching is as follows, and a conceptual image thereof is shown in FIG. In FIG. 2, solid lines indicate command values for position, load, and hydraulic servo valve opening, and broken lines indicate actual values of position and load.

  Hereinafter, events from “control switching” to “arrival of set load” in FIG. 2 will be described with reference to FIG.

(1) Immediately before switching from position control to load control, the opening command value (for example, 10%) of the hydraulic servo valve 3 for maintaining the current roll position is output from the position control circuit 6 to the hydraulic servo valve 3. ing.
(2) Immediately after switching from the position control to the load control, the load command value and the actual load value coincide with each other, so that proportional amplification and integral storage are not performed. Further, since the value obtained by dividing the opening command value of the hydraulic servo valve 3 of the position control circuit 6 so far by the integral gain (Ki) of the integrator 8b is stored as the initial value of the integrator 8b, the load control circuit 8 The opening command value of the hydraulic servo valve 3 coincides with the value (for example, 10%) output by the position control circuit 6, and the opening of the hydraulic servo valve 3 in the position control is taken over. As a result, Load variation does not occur. That is, this state is the same as the state where the load control circuit 8 controls the load control value to an arbitrary load command value (in this case, the actual load value at the time of switching) and settles.
(3) Immediately after the control switching from the position control to the load control, the switch S2 is turned off and the switch S3 is turned on. Then, the rate generator 8c increases the load command value at a constant rate toward a set load (for example, 500 t), and starts operation at the set load.

  As described above, according to the control method of the present invention, at the start of rolling, load change does not occur when switching from position control to load control, and the set load can be smoothly reached. Moreover, the holding | maintenance by a control switching load becomes unnecessary. This effect of the present invention is apparent when FIG. 2 is compared with FIG.

DESCRIPTION OF SYMBOLS 1a Upper work roll 1b Lower work roll 2a Upper backup roll 2b Lower backup roll 3 Hydraulic servo valve 4 Hydraulic cylinder 5 Position sensor 6 Position control circuit 6a Proportional amplifier 7 Load sensor 8 Load control circuit 8a Proportional amplifier 8b Integrator 8c Rate generator DESCRIPTION OF SYMBOLS 11 Control circuit 11b Initial correction value 11c Position / load switching operation part A Position control circuit B Load control circuit S1-S6 Switch S Steel plate

Claims (1)

A control method for a skin pass mill that performs temper rolling of a steel sheet by reducing a roll with a hydraulic servo,
During non-rolling, based on the deviation between the position command value and the actual position value of the roll detected by the position sensor, the position control circuit performs position control to output the opening command value of the hydraulic servo valve,
During rolling, based on the deviation between the load command value and the actual load value on the steel plate detected by the load sensor, the load control circuit performs proportional and integral operations to output the opening command value of the hydraulic servo valve. And
When switching from position control to load control, the actual load value on the steel plate detected by the load sensor at the time of switching is used as the first load command value for load control, and the hydraulic servovalve output from the position control circuit A skin pass mill control method in which a value obtained by dividing an opening command value by an integral gain of an integrator that performs an integral operation in a load control circuit is stored as an initial value of the integrator.

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