JPH1094281A - Load control method and load control device in rolling mill drive motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily control the load of a motor to a present tolerance or lower by a method wherein the load on the motor is estimated on the basis of an actual value and a roll speed is reduced and controlled in such a way that the estimated value of the load does not exceed the tolerance when the estimated value exceeds the tolerance. SOLUTION: In a control apparatus body 18, the future load on a motor 14 is estimated on the basis of the actual result of the load on the motor 14 up to the present time, the speed of rotation of the motor 14 is adjusted by a roll-speed regulating device 20 in such a way that an estimated value does not exceed a tolerance, and a roll speed is controlled. At this time, the load of the motor 14 is controlled by measuring a new actual result value at every proper time interval until a roll operation is finished. Thereby, it is possible to easil prevent the damage or the like due to the thermal load on the motor 14 without sharply lowering the efficiency of the roll operation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a load control method and a load control apparatus for a motor, in which a rolling speed is adjusted so that a motor load does not exceed an allowable value in a rolling mill of a type in which a rolling roll is driven by an electric motor. .

[0002]

2. Description of the Related Art As a driving means of a rolling roll in a rolling mill, an electric motor is preferably employed because high-precision control can be easily performed. In this case, the motor is driven in a range very close to the load allowable value in some cases in order to secure excellent rolling efficiency, but in order to prevent damage to the motor, the motor load is changed due to changes in rolling conditions and the like. Must be prevented from exceeding the allowable value.

Therefore, conventionally, for example, Japanese Patent Application Laid-Open No.
As described in Japanese Patent No. 4086 and the like, the thermal load of the motor is calculated using the root-mean-square method in consideration of the fact that the allowable value of the motor load is determined mainly by the temperature rise due to heat generation. , The value was controlled so as not to exceed the allowable value.

However, as described in the above publication, the conventional management method is based on the value of the thermal load of the motor up to the present time, which is obtained as a root-mean-square value considering only past performance values. Therefore, it is extremely difficult to determine whether the thermal load of the electric motor may exceed an allowable value if rolling is continued during the rolling operation. Since it is difficult to predict the thermal load of the electric motor in the future in this way, if the obtained thermal load at the present time approaches the allowable value, the operator may not be able to take safety into account. Although the rolling efficiency may be greatly reduced by lowering the motor load as necessary, there is also a risk that the motor may be damaged due to exceeding the allowable value because the safety is estimated low.

[0005] Therefore, it is extremely difficult to perform stable control of the electric motor while securing sufficient rolling efficiency.
There was also a problem that the operator's experience and the like were required and the labor burden was large.

[0006]

The present invention has been made in view of the above-mentioned circumstances, and the problem to be solved is to predict the motor load during the rolling operation in the future, and A load control method and load control for a rolling mill driving motor that can easily control the motor load to an allowable value or less while avoiding unnecessary reduction in rolling efficiency by adjusting the motor load according to the predicted value. It is to provide a device.

[0007]

In order to solve such a problem, the invention according to claim 1 is characterized in that, at a predicted time point during a rolling operation by a rolling mill, a load of a motor for driving a rolling mill within a remaining rolling time until the end of rolling is reduced. Is predicted based on the actual value up to the prediction time point. If the predicted value of the motor load exceeds a preset allowable value, the rolling is performed so that the predicted value of the motor load does not exceed the allowable value. A feature of the present invention is a load control method in a rolling mill driving motor that reduces and corrects the speed.

According to the method of the present invention, during the rolling operation, the motor load is predicted until the end of the rolling by the prediction calculation based on the actual value. If rolling is continued as it is based on the obtained specific predicted value, it is determined whether or not the motor load will exceed the allowable value in the future.

Therefore, according to the method of the present invention in which the motor load is adjusted based on the predicted value of the future motor load specifically obtained, only the past value of the motor load up to the present time is used as a basis for determination in the future. As compared with the conventional method of adjusting the load of the electric motor, the adjustment of the electric motor load is facilitated, stable electric motor load control is realized, and the labor of the operator can be reduced.

[0010] The invention described in claim 2 is the same as the claim 1.
In the method of the invention described in the above, the load control method in the rolling mill drive motor to perform the prediction of the motor load within the remaining rolling time by the root mean square method using the actual value of the motor load up to the prediction point, I do.

According to the method of the present invention, a future motor load can be easily and accurately predicted. Also, according to the rolling schedule, etc.
By adjusting the range of past performance values to be considered in the root mean square method (time to be considered backward from the point to be predicted), it is possible to adjust the prediction accuracy of the motor load and the like. In the method according to the first aspect of the present invention, depending on the type of electric motor, rolling schedule, and the like,
It is also possible to predict the motor load within the remaining rolling time by the average loss method or the like.

Further, the invention described in claim 3 is the first invention.
Or in the method of the invention described in 2, the load in the rolling mill driving motor for predicting the motor load after assuming that the motor torque and the motor rotation speed at the predicted time continue until the rolling end time after the predicted time. A control method is characterized.

According to the method of the invention described in claim 3, it is possible to advantageously predict the future motor load. In particular, in combination with the method of the invention described in claim 2, By predicting the future motor load by the root-mean-square method assuming that the motor torque and the like continue until the end of rolling, the actual value of the motor load up to the prediction point is advantageously considered, and a higher accuracy Prediction becomes possible.

The invention described in claim 4 is the first invention.
4. The method according to any one of claims 1 to 3, wherein the predicted value of the motor load exceeds the allowable value, the deceleration correction amount of the rolling speed is reduced, and the predicted value of the motor load does not exceed the allowable value. The method is characterized by a load control method in the electric motor for driving a rolling mill, which is gradually increased until the predicted value becomes equal to or less than the allowable value, and adopts the deceleration correction amount.

According to the method of the present invention, the motor load can be advantageously adjusted within an allowable range without unnecessarily reducing the rolling efficiency.

The invention described in claim 5 is the first invention.
In the method according to any one of (1) to (4), during the rolling operation by the rolling mill, at each sampling point set at an appropriate time interval, the actual value of the motor load is measured, and the actual value is used. The load at each sampling point in the remaining time after the prediction time is predicted and calculated, and if at least one of the predicted values of the motor load at each sampling point exceeds the allowable value, the rolling speed is reduced. A load control method in the electric motor for driving a rolling mill to be corrected is characterized.

In the method according to the present invention, the motor load at each sampling point within the remaining time is predicted based on the actual value measured at each past sampling point. And, since the rolling speed is modified to reduce the motor load if at least one of the predicted values exceeds the allowable value, the motor load can be advantageously adjusted within the allowable value range. Also,
By adjusting the sampling period, it is also possible to adjust the degree of influence of past actual values on predicted values.

The invention described in claim 6 is the same as the invention in claim 5
In the invention method described in the above, the calculation of the predicted value of the motor load at each of the sampling points and the comparison between the predicted value of the motor load and the allowable value are performed at each of the sampling points. A control method is characterized.

In the method according to the sixth aspect of the invention, every time the rolling operation proceeds and reaches a new sampling point, the predicted value is updated based on the actual value of the newly sampled motor load. As a result, the accuracy of the predicted value and thus the control accuracy of the motor load are further improved.

The invention described in claim 7 is the first invention.
7. The method according to any one of claims 1 to 6, wherein the rolled material is continuously passed through the continuous rolling at a time interval shorter than a rolling time considered to determine at least one predicted value of the motor load. The load control method in the electric motor for driving a rolling mill is characterized by the following.

In the method according to the present invention, the motor load at the time of passing the next rolled material is appropriately adjusted based on the actual value at the time of passing the at least one previous rolled material. Therefore, stable continuous rolling can be advantageously achieved.

Further, the invention according to claim 8 is characterized in that (a)
During the rolling operation by the rolling mill, the load of the motor for driving the rolling mill, sampling means for measuring at appropriate time intervals,
(B) a time measuring means for determining a remaining rolling time at a predicted point in time during the rolling operation; and (c) a remaining rolling time obtained by the aging means based on the actual value of the motor load measured by the sampling means. Motor load predicting means for predicting and calculating the motor load in step (d); comparing means for comparing the predicted value of the motor load obtained by the motor load calculating means with a preset allowable value; A correction amount calculating means for calculating a correction amount for reducing the rolling speed at which the predicted value is equal to or less than the allowable value when the predicted value of the load is larger than the allowable value; and (f) a deceleration calculated by the correction amount calculating means. And a rolling speed adjusting means for adjusting the rolling speed of the rolling mill according to the correction amount.

In the load control device having the structure according to the eighth aspect of the present invention, the future motor load when the rolling operation is continued during the rolling operation is predicted and calculated as a specific value. Therefore, it is easy to determine whether or not the motor load will exceed the allowable value in the future, and it is easy to adjust the motor load, thereby achieving a stable rolling operation and reducing the operator's labor. .

The motor load predicting calculation by the motor load calculating means may be performed intermittently at appropriate time intervals, for example, by a root-mean-square method using the past actual values within the remaining rolling time until the end of rolling. Is desirably performed for a plurality of prediction points in. Further, at that time, it is effective to predict the motor load by the root-mean-square method, assuming that after the prediction time, the motor torque and the motor rotation speed at the prediction time continue until the rolling end time.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, in order to clarify the present invention more specifically, a description will be given while exemplifying more specific embodiments of the present invention.

First, FIG. 1 shows a schematic configuration example of a rolling mill structure for carrying out the present invention. 10 is
It is a main part of a rolling stand of a rolling mill.
By rotating the motor 12 by the electric motor 14, the rolling material 16 passed between the rolling rolls 12 is rolled. Further, at the time of rolling, in order to stably obtain the desired rolled material with good rolling efficiency, by controlling the rotation speed and the amount of reduction of the electric motor 14 by a control system (not shown) according to a known method. In addition, tension control, rolling down control, and the like are performed. In this configuration example, only one rolling stand 10 is shown, but in addition to a single-stand rolling mill,
A tandem rolling mill may be used. The types of rolling mills are not limited at all. For example, rough rolling mills and finishing rolling mills, various rolling mills such as two-stage and four-stage types, cold rolling mills and hot rolling mills, and aluminum rolling mills Regardless of the type of rolling mill or steel rolling mill, any kind of rolling mill may be used.
Further, in this configuration example, only a single electric motor 14 for driving the lower rolling roll 12 is shown, but the upper and lower rolling rolls 12 are rotatably driven by independent electric motors. Is also good.

The motor load control system controls the rolling speed and thus the motor 14 so that the load on the motor 14 for driving the rolling roll 12 does not exceed an allowable value.
The load is adjusted. This load control system includes a control device main body 18 and a rolling speed adjusting device 20. The control device main body 18 controls the motor 1 based on the actual value of the load of the motor 14 up to the present time.
4, the rolling speed is controlled by adjusting the number of revolutions of the electric motor 14 by the rolling speed adjusting device 20 so that the predicted value does not exceed the allowable value.

More specifically, the control device main body 18 is constituted by a computer.
First, a load actual value required for the load prediction of the electric motor 14 up to the present time, which is the prediction time, is stored in the memory. The load of the motor 14 (motor load) is regarded as a thermal load, and generally, a power ratio: PWR
Is obtained by the following (Equation 1). PWRi = (τi / τc) × (Ni / Nc) (Equation 1) where PWR: power ratio (%), τ: actual torque, τ
c: Rated torque of motor, N: Number of rotations of motor (however,
In the case of N <Nc, it is assumed that N = Nc), Nc: base rotation speed of the electric motor, i: NO.

The torque and the number of revolutions of the electric motor 14 necessary for obtaining the thermal load are measured directly from a sensor mounted on the electric motor 14 or indirectly by calculation from a current value or the like, and are controlled. The data is input to the apparatus main body 18. Further, the sampling points for obtaining the thermal load can be set at appropriate time intervals. In this configuration example, the sampling points are set every 10 seconds, and only for 30 points, that is, in the past 5 The actual value of the thermal load every 10 seconds in a minute is stored in the memory of the control device main body 18.

In short, in the present configuration example, in the above (Equation 1), i = 1, 2, 3,...
With respect to the actual values at the sampling points (storage points), as the rolling operation progresses, the latest values are stored in memory and the oldest values are deleted at the same time every 10 seconds. As is apparent from this, in the present configuration example, the calculation program of the above (Equation 1) in the apparatus main body 18 and the detection sensor of the torque and the rotation speed of the electric motor 14 are included. Sampling means for measuring the load at a suitable time interval is provided.

The control device body 18 includes a rolled material 16.
Of the material on the inflow side, the sheet thickness, the sheet thickness on the outflow side, and the like, and the remaining rolling time is obtained from these values. Specifically, the remaining rolling time: td is obtained, for example, according to the following (Equation 2), (Equation 3) and (Equation 4). td = dL / V (Equation 2) where td: remaining rolling time, dL: remaining pressure extension, V:
Rolling speed. dL = L−Σ (V × dt) (Equation 3) where L: pressure extension (full length), dt: sampling pitch (time interval between sampling points). L = Lin × (Hin / Hout) (Equation 4) where, Lin: material length on the incoming side of the rolling mill, Hin: thickness on the incoming side of the rolling mill, Hout: thickness on the outgoing side of the rolling mill.

As is apparent from these equations, this configuration example includes a calculation program for executing the above (Equation 2), (Equation 3) and (Equation 4) in the apparatus main body 18, and the like.
A time measuring means for obtaining a remaining rolling time at a predicted time during the rolling operation is configured.

It is possible to directly measure the entry material length, entry plate thickness, and exit plate thickness of the rolling mill required to determine the remaining rolling time. The calculated value obtained can be adopted. Further, since the change in the sheet width dimension of the rolled material due to rolling is extremely small as compared with the change in the length of the rolled material, it was not considered in the above (Equation 4).

Then, based on the actual value of the thermal load of the electric motor 14 obtained by the above (Equation 1): PWRi,
In order to obtain a predicted value of the motor load within the remaining rolling time after the prediction time, the root mean square method is suitably employed.
Specifically, for example, first, based on the remaining rolling time: td (second) obtained in the above (Equation 2), the number of sampling points: j set at intervals of 10 seconds after the prediction point is calculated by the following (Equation 5) ). j = td / 10 (Equation 5) where j is an integer value obtained by truncating the decimal part.

Then, with each sampling point (j = 1, 2,... Td / 10) in the remaining rolling time as a prediction point, the predicted value P of the thermal load of the motor at each prediction point is squared. According to the averaging method, it is calculated by the following (Equation 6), (Equation 7) and (Equation 8). In this configuration example, one cycle of the load in the root mean square value is set to 5 minutes,
The number of sampling points before the prediction point to be considered in one prediction point was set to 300 seconds / 10 seconds = 30. Also,
At this time, the thermal load at the sampling point before the prediction point but after the prediction time (current time) is the same as the prediction time, assuming that the motor torque and motor speed at the prediction time continue until the end of rolling. It is effective to adopt a thermal load of

(A) Prediction point of 1 <j ≦ 30

(Equation 6) Where P is the root mean square predicted value of the thermal load in the motor,
PWRk: actual value of thermal load obtained and stored in the above (Equation 1) before current time, PWRF: assumed value of thermal load after current time, j: NO. Of predicted point,
k: Subscript. PWRF = (τ / τc) × (N / Nc) (Equation 7) where τ: Actual torque of the motor at the time of prediction, N:
Actual number of rotations of the motor at the time of prediction (however, N <Nc
, N = Nc). (B) Predicted point of 30 <j P = √ ((PWRF × PWRF × 30) / 30) = PWRF (Equation 8) where P: root mean square predicted thermal load of the motor,
PWRF: Assumed value of thermal load after the present time.

By taking the mean value of the motor load at each prediction point in consideration of the actual value of the motor load before the prediction time, a future motor load at the time of continuing the rolling operation up to the prediction time is considered. Can be advantageously predicted, and the actual finish rolling of the aluminum alloy was examined. The difference between the predicted value and the actually measured value was suppressed to about ± 10%, and was at a level that was sufficiently acceptable for practical use. It has been confirmed that there is.

As is apparent from this, in the present configuration example, the above (Equation 5),
The motor load calculating means for predicting and calculating the motor load within the remaining rolling time is included, including a calculation program for executing (Equation 6), (Equation 7) and (Equation 8).

Subsequently, each predicted point obtained in this way is:
The predicted value P of the motor load at j = 1, 2,..., td / 10 is compared with a motor load allowable value input and set in advance, respectively. This comparison operation is also performed in the control device body 18 according to a comparison execution program.

If the predicted value P is larger than the allowable value at at least one predicted point, the rolling speed is reduced and corrected. This correction operation is performed, for example, by calculating the rolling speed after any one of the prediction points subsequent to the prediction time point or thereafter, that is, the predicted value of the motor load when the rotation speed of the motor 14 is reduced by a certain value: PWRF as follows ( Predicted value obtained according to equation 9): PWRF
By substituting into the above (Equation 6) and (Equation 8), the motor load in the remaining rolling time is reviewed. PWRF = (τ / τc) × ((N−dN) / Nc) (Equation 9) where dN is a change amount of the rotation speed of the electric motor.

This operation is repeated until the motor load within the remaining rolling time does not exceed the allowable value, and the amount of change in the number of revolutions of the motor required to prevent the motor load from exceeding the allowable value: dN is obtained. In this case, it is possible for the operator to input the appropriate change amount: dN each time by looking at the magnitude of the predicted value of the motor load: PWRF. On the other hand, the operation can be simplified by sequentially substituting values that gradually increase from small values and adopting the change amount: dN when the motor load does not exceed the allowable value first.

As is clear from this, in the present configuration example, the rolling speed at which the predicted value of the motor load is equal to or less than the allowable value in the apparatus main body 18 (including the calculation program for executing the above equation 9). The correction amount calculating means for obtaining the deceleration correction amount of the above is constituted.

The rotation speed of the motor 14 is decelerated by the rolling speed control device 20 in accordance with the change amount dN of the rotation speed of the electric motor as the change amount of the rolling speed obtained in this manner. That is, the load control of the electric motor 14 is executed.

Further, as described above, the future load is predicted based on the actual load value obtained by sampling the motor load, and the rolling speed is compared with the allowable value so that the load does not exceed the allowable value. , A series of load control of the electric motor is continuously and repeatedly executed until the end of the rolling. That is, a new actual value is measured at an appropriate time interval (10 seconds in this configuration example), and the load at each prediction point in the remaining rolling time is re-estimated in consideration of the new actual value.
High-precision motor load control can be realized.

Therefore, if such motor load control is employed, the future motor load is predicted and calculated as a specific value at each prediction point, and compared with an allowable value by a specific numerical value. Thus, the adjustment amount of the motor load is determined. Therefore, as compared with the conventional adjustment based on the experience and intuition of the operator, it is easy to prevent the damage due to the thermal load of the electric motor without greatly reducing the rolling efficiency, thereby stabilizing the rolling operation and It is possible to advantageously reduce the operator's labor and the like.

Hereinafter, in order to more specifically clarify the technical significance of the present invention, examples of the present invention will be described. However, the present invention is not limited to the specific description in the above description and the following examples. The description is not to be construed as limiting in any way, and various changes, modifications,
It is needless to say that the present invention can be carried out in an embodiment in which improvements and the like are added, and all such embodiments are included in the scope of the present invention unless departing from the gist of the present invention. It goes without saying that there is something.

[0047]

EXAMPLE In a hot-finished plate rolling model of an aluminum alloy using a four-stand tandem rolling mill, a load control for adjusting a rolling speed based on a predicted value of a motor load obtained according to a root-mean-square method was performed in the same manner as in the above configuration example. FIG. 2 shows a simulation result when the load control is performed, and FIG. 3 shows a simulation result when the load control is not performed as a comparative example.

In these simulations, a case where continuous rolling was performed on a coil that completed rolling in about 240 seconds was examined. In addition, the sampling pitch, the calculation method based on the root-mean-square (load cycle and the like), and the like are all in accordance with the above configuration example. Furthermore, the allowable value of the motor load was set to 118% in power ratio.

As a result of the simulation, when the load control according to the present invention was not performed, as shown in FIG. 3, the motor load of the NO. 3 stand (evaluated by the root mean square) exceeded the allowable value. However, it is recognized that by performing the load control according to the present invention, as shown in FIG. 2, the motor load (mean square value) can be controlled to be equal to or less than the allowable value at all the stands, The effectiveness of the load control according to the present invention has been confirmed.

[0050]

As is apparent from the above description, according to the motor load control method of the present invention as set forth in any one of claims 1 to 7, the future motor load when the rolling operation is continued is predicted. Once calculated, it can be easily determined whether the value will exceed the allowable value in the future, and furthermore, the adjustment of the motor load within the allowable value can be easily performed.
A stable rolling operation is advantageously achieved, and the labor of the operator is greatly reduced.

Also, in the motor load control device having the structure according to the present invention described in claim 8, the invention described in claim 1 can be advantageously implemented, whereby the motor load can be advantageously reduced. It can be adjusted easily and easily, and it is possible to secure excellent rolling efficiency while preventing troubles such as damage due to thermal load of the electric motor.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration example of a rolling mill for carrying out the present invention.

FIG. 2 is a graph showing a simulation result as an example of the present invention.

FIG. 3 is a graph showing a simulation result as a comparative example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Rolling stand 14 Electric motor 16 Rolled material 18 Control device main body 20 Rolling speed adjustment device

Claims (8)

[Claims] At a prediction time during a rolling operation by a rolling mill, a load of a motor for driving a rolling mill within a remaining rolling time until the end of rolling is predicted based on an actual value up to the prediction time. When the predicted value exceeds a predetermined allowable value, the rolling speed is reduced and corrected so that the predicted value of the motor load does not exceed the allowable value. Method. 2. The load control method according to claim 1, wherein the prediction of the motor load during the remaining rolling time is performed by a root-mean-square method using the actual value of the motor load up to the prediction time. . 3. The motor load is predicted on the assumption that the motor torque and the motor rotation speed at the predicted time continue until the rolling end time after the predicted time.
The load control method in the electric motor for driving a rolling mill according to the above. 4. When the predicted value of the motor load exceeds the permissible value, the correction amount of the rolling speed deceleration is gradually increased until the predicted value of the motor load does not exceed the permissible value. 4. The load control method according to claim 1, wherein a deceleration correction amount at the time when the predicted value is equal to or less than the allowable value is adopted. 5. During a rolling operation by a rolling mill, actual values of the motor load are measured at each sampling point set at appropriate time intervals, and the actual values are used to calculate the actual value of the motor load after the prediction time. The load at each sampling point in the remaining time is predicted and calculated, and if at least one of the predicted values of the motor load at each sampling point exceeds the allowable value, the rolling speed is reduced and corrected. The load control method in the electric motor for driving a rolling mill according to any one of the above. 6. The rolling mill drive according to claim 5, wherein the calculation of the predicted value of the motor load at each of the sampling points and the comparison between the predicted value of the motor load and the allowable value are performed for each of the sampling points. Load control method for electric motors. 7. The rolling material according to claim 1, wherein the rolled material is continuously passed through at least at a time interval shorter than a rolling time considered for obtaining at least one predicted value of the motor load. A load control method in the electric motor for driving a rolling mill according to any one of the above. 8. Sampling means for measuring the load on the electric motor for driving the rolling mill at appropriate time intervals during the rolling operation by the rolling mill, time measuring means for obtaining the remaining rolling time at a predicted time during the rolling operation, Motor load calculating means for predicting and calculating the motor load within the remaining rolling time determined by the aging means based on the actual value of the motor load measured by the sampling means; and the motor determined by the motor load calculating means. The predicted load is
Comparing means for comparing the predicted value of the motor load with the predetermined allowable value; and a correction amount calculation for calculating a deceleration correction amount of the rolling speed at which the predicted value is equal to or less than the allowable value when the predicted value of the motor load is larger than the allowable value. And a rolling speed adjusting means for adjusting a rolling speed of the rolling mill according to the deceleration correction amount obtained by the correction amount calculating means.