JPS62187513A - Tension control method for tandem rolling mill - Google Patents

Abstract

PURPOSE:To keep the high accurate plate thickness with a tension between stands stably covering the total coil length by correctively controlling a rotating speed of the stand preceding the final stand and of the final stand based on outputs from a controlled variable arithmetic unit. CONSTITUTION:A tension detected by a tension meter 7 set between the stand 2 preceding the final stand 3 and the final stand 3 is compared with the tension target value 12 at a controlled variable arithmetic unit 22. Then, proportional plus integral arithmetic is performed and a control command is outputted to correct a plate thickness at the outlet side of the stand 2 to be thinner. A screwdown position correcting device 23 of the stand 2 controls a screwdown device 21 so as to correct a screwdown position of the stand 2 in the direction where a roll gap is closed. Outputs of the unit 22 are inputted into a roll speed correcting device 24 of the stand 3 and the device 24 calculates and outputs a command decreasing the final stand roll speed so that a plate thickness at the outlet side of the stand 2 corrected by the device 23 does not affect a finished plate thickness.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a tension control method for a tandem rolling mill.

BACKGROUND OF THE INVENTION In general, the ultimate goal of a rolling mill is to make the exit side thickness of the final stand, ie, the finished thickness, match a target value over the entire length of the steel strip. If the deviation between the finished plate thickness and the target value exceeds the allowable range, the plate becomes so-called off-gauge and must be discarded as scrap in the inspection process, resulting in a significant decrease in yield.

On the other hand, in the operation of a tandem rolling mill, the most important thing is to stabilize the tension applied to the rolled material between the stands. If the stand opening tension of the rolled material is higher than a certain upper limit, the rolled material may break due to excessive tension, and if it is lower than a certain lower limit, it may be narrowed due to loss of tension. There is a risk of breakage. When such an accident occurs, a large amount of rolled material must be scrapped. Furthermore, there is a high possibility that the rolls will be damaged (in this case, the rolls will have to be replaced, which will significantly reduce rolling efficiency).

Against this background, various devices have been proposed as control devices for the finished plate thickness and the tension between the stands. A typical example of this type of conventional technology is the technology described in Japanese Patent Publication No. 51-25828.

Referring to the attached FIGS. 5 and 6, the conventional tension control and plate thickness control device described in Japanese Patent Publication No. 51-25828 mentioned above will be briefly described.

FIG. 5 shows the operation of a conventional tension and plate thickness control device in a tandem rolling mill during sheet passing.

As shown in FIG. 5, this prior art tension and plate thickness control device is disposed on a final pre-stage stand 2 and a final stand 3 that continuously roll a material to be rolled 1 traveling in the direction of arrow F. These final pre-stage stand 2 and final stand 3 are equipped with roll drive motors 4 and 5, respectively, a thickness gauge 6 is provided on the exit side of final stand 3, and a tension gauge 7 is provided between final pre-stage stand 2 and final stand 3. is provided. This prior art tension and thickness control device
A tension control device 11 that receives the detection signal from the tension meter 7 manually.
, a roll speed control device 13, and a plate thickness control device 14 which receives the output signal of the thickness gauge 6 manually.

During rolling mill rolling, the tension control device 11 determines the output signal to the roll speed control device 13 according to the deviation between the preset tension target value 12 and the output value of the tension meter 7, so that the tension is constant. The roll drive motor 5 is controlled so that.

As shown by the dotted line in FIG. 5, the roll speed control device 13 is configured to manually input the output signal of the plate thickness control device 14 on the circuit, but the plate thickness control is not started during sheet threading. The roll speed is essentially corrected only by the output of the tension control device 11. The dotted line in the figure indicates this state.

Next, FIG. 6 shows the operation of the conventional tension and plate thickness control device shown in FIG. 5 during steady rolling. According to this prior art, during steady rolling, the plate thickness control device 14 outputs an output to the roll speed control device 13.

On the other hand, a dead zone is set in the tension control device 11, and no signal is output for tension fluctuations within a certain range. The dotted line in the figure indicates this situation.

That is, in the conventional technology, during sheet threading, sheet thickness control is not performed, and only tension control is substantially performed;
During steady rolling, only plate thickness control was substantially performed.

Problems that the invention attempts to solve The problems of the conventional techniques described above will be explained below.

As mentioned above, according to the prior art, when threading, the fifth
As shown in the figure, tension control is performed to prevent tension fluctuations, but plate thickness control is not performed, and as a result, plate thickness fluctuations occur in order to control tension.

However, in recent years, with advances in plate thickness control technology, the accuracy of plate thickness in the steady rolling section has improved significantly, and the most important issue from the perspective of reducing off-gauge length is how to prevent plate thickness fluctuations during rolling. This is an important matter. Furthermore, customers of copper strips are demanding more accurate plate thickness than ever before. Under such circumstances, there is a big problem in leaving the variation in plate thickness during sheet threading as in the above-mentioned prior art.

On the other hand, during steady rolling, as shown in FIG. 6, plate thickness control was carried out by allowing tension fluctuations to some extent. In recent years, from the perspective of energy conservation, the heating of steel slabs during the earth rolling process has been reduced, and this tends to increase the variation in deformation resistance of rolled materials in the longitudinal direction. Therefore,
Tension fluctuations during rolling have become larger than ever before.

According to the above-mentioned conventional technology, this tension fluctuation is not controlled during steady rolling, which may seriously impede smooth operation. In particular, during steady rolling, the rolling speed is higher (approximately 10 to 20 times) than during sheet passing, so if plate breakage occurs due to tension fluctuation, the damage is particularly significant. Furthermore, when the inter-stand tension fluctuates beyond the dead zone, the tension control device 11 outputs a signal to the roll speed control device 13 in order to suppress this. This control output becomes a disturbance to the plate thickness control and causes plate thickness fluctuations. If off-gauge occurs in the steady rolling portion due to such plate thickness fluctuations, the yield will further decrease.

The present invention has been made in view of the above-mentioned state of the prior art, and provides a technology for constantly controlling inter-stand tension fluctuations without affecting plate thickness, regardless of whether during sheet passing or steady rolling. The purpose is to provide the following.

Means for Solving the Problems According to the present invention, in order to achieve the above object, in a tension control method for a tandem rolling mill constituted by two or more stands, the n-th stand and the upstream-side ( n-1) Detecting the tension with the stand, calculating the deviation between the detected tension value and the target tension, and performing a proportional integral calculation on the tension deviation in order to eliminate the tension deviation, and the calculation result. Successfully correct the roll speed of the (n-1)th stand and the n-th stand by
A tension control method for a tandem rolling mill is provided, which is characterized in that the roll speed of an n stand is corrected so as to zero the plate thickness variation on the exit side of the stand.

Furthermore, according to the present invention, in a tension control method for a tandem rolling mill configured with two or more stands, the tension between the nth stand and the upstream (n-1)th stand adjacent thereto is detected, calculating the deviation between the detected tension value and the target tension, and performing a proportional integral calculation to eliminate the tension deviation; correcting the lowering position of the (n-1)th stand based on the calculation result; Based on the results, there is provided a tension control method for a tandem rolling mill, comprising: modifying the roll speed of the n-stand in order to zero the plate thickness variation on the outlet side of the n-th stand due to the modification of the rolling position.

According to a preferred embodiment of the present invention, the tension control device further calculates the travel time of the rolled material from the (n-1)th stand to the n-th stand based on the roll speed of the (n-1)th stand, and Means is provided for delaying the output signal of the means for modifying the roll speed of the stand.

Fraud J In the present invention, regardless of whether the sheet is threaded or during steady rolling,
At the same time as the tension is constantly controlled, the roll rotation speed of the downstream stand is controlled to compensate for variations in plate thickness caused by the tension control.

Therefore, even during sheet threading, there is little variation in sheet thickness, and on the other hand,
Even during steady rolling, control can be achieved with less tension fluctuation. In this way, it is possible to reduce the off-gauge at the tip of the rolled material and improve the yield, and at the same time,
By reducing tension fluctuations during steady rolling, plate breakage, off-gauge plate thickness, or roll damage can be reduced, and rolling yield and rolling efficiency can be improved.

Examples of the present invention will be described below with reference to the accompanying drawings, but it goes without saying that these examples are merely illustrative of the present invention and do not limit the technical scope of the present invention in any way. It is.

Embodiment FIG. 1 is a schematic diagram of a tension control device used in an embodiment of the tension control method of the present invention.

As shown in FIG. 1, this tension control device is shown in an example in which it is disposed on a final pre-stage stand 2 and a final stand 3 that continuously roll a rolled material 1 traveling in the direction of the arrow F. These final front stand 2 and final stand 3
are equipped with roll drive motors 4 and 5, respectively, a thickness gauge 6 is provided on the exit side of the final stand 3, and a tension gauge 7 is provided between the final pre-stage stand 2 and the final stand 3. Furthermore, reference numeral 21 indicates a lowering device of the final pre-stage stand 2.

The tension control device according to this embodiment includes a tension control device 22 to which a detection signal from the tension meter 7 is input;
A final pre-stand roll speed correcting device 23 receives an output signal from the final stand roll speed correcting device 23, a final stand roll speed correcting device 24 receives an output signal from the tension control device 22, and a final stand roll speed correcting device 24 receives an output signal from the final stand roll speed correcting device 24. and a material transfer time calculation device 25 that is maintained at the same time.

Based on the output value of the tension meter 7 and the target tension value 12, the control amount calculation device 22 performs a proportional integral calculation as shown in the following equation in order to correct the deviation.

X22; Controlled amount to the output of the hydrochloric acid device 22 22: Proportional gain T22: Integral time S Nira plus operator △T: Tension deviation Multiply by a preset coefficient like .

23 to X23-.X22

Further, the output signal of the control amount calculation device 22 is input to the final stand roll speed correction device 24, and the final stand roll speed correction device 24 sets the output signal of the control amount calculation device 22 in advance as shown in the following equation. Multiply the coefficient.

X24 = X241 X24
This is to determine the amount of final stand roll speed correction that does not affect the final stand exit side plate thickness. On the other hand, the material transfer time wave calculation device 25
Based on the rotational speed of the roll drive motor 4 of motor 5
is configured to control the For example, it is calculated as follows.

X25: The output of the material transfer time calculation device 25: Distance between the final pre-stage stand 2 and the final stand 3 ■: The roll peripheral speed reference number 26 of the final pre-stage stand 2 is a normal plate thickness control device, and the final stand The deviation between the output of the thickness meter 6 on the exit side of No. 3 and the target plate thickness is proportionally integrated, and the speed of the roll drive motor of the final stand 3 is corrected using this value to control the exit side sheet thickness of the final stand 3 at a constant value. do.

The tension control device of the present invention is similar to the conventional plate thickness control device 26.
It can also be used over and over again.

Now, the operation of the tension control device of the present invention shown in FIG. 1 will be explained. Here, control when the tension between the final pre-stage stand 2 and the final stand 3 becomes higher than the target value will be explained.

The tension detected by the tension meter 7 between the final pre-stage stand 2 and the final stand 3 is compared with the tension target value 12 in the control amount calculation device 22, and the tension is adjusted to reduce the outlet side plate thickness of the final pre-stage stand 2. , proportional-integral calculations are performed, and a control command is output. Based on this, the final front stage stand rolling position correction device 23 controls the rolling down device 21 to correct the rolling position of the final front stage stand 2 in the roll gap closing direction.

As described above, the output of the control amount calculation device 22 is also input manually to the final stand roll speed correction device 24. The final stand roll speed correction device 24 issues a command to reduce the final stand roll speed so that the thickness of the exit side of the final pre-stage stand corrected by the final pre-stage stand reduction position correction device 23 does not affect the finished plate thickness. Calculate and output. In other words, by reducing the final stand roll speed, the tension between the final pre-stage stand 2 and the 1ζ final stand 3 is reduced, which has the effect of increasing the finished plate thickness, which is the effect of correcting the thinning of the plate thickness at the exit side of the final pre-stage stand. Offsetting this, there is no change in the finished plate thickness. In addition, due to the effect of reducing the tension mentioned above,
The tension is brought as close as possible to the target value.

In order to achieve this plate thickness correction effect with high accuracy, it is preferable that the material transfer time calculation device 25 performs time delay processing that takes into account the time required to move the rolled material 1 from the final pre-stage stand 2 to the final stand 3.

In this way, the tension between the stands that was higher than the target value was
It can be seen that the target value can be corrected without affecting the finished plate thickness in any way.

FIG. 2 is a schematic diagram of a tension control device according to another embodiment of the invention. Parts that are the same as the tension control device shown in FIG. 1 are designated by the same reference numerals. Further, description of the same parts as those of the tension control device shown in FIG. 1 will be omitted.

In the tension control device of this embodiment, the final pre-stage stand reduction position correction device 23 is not provided, and in order to control the exit side plate thickness of the final pre-stage stand 2, the roll speed correction device 23 is not provided.
7 is provided. The roll speed correction device 27 receives the output of the control amount calculation device 22, and adjusts the drive motor 4 of the final pre-stage stand 2 and the final stand 3 based on this output signal.
．． Successfully control 5. That is, the rotational speeds of the final pre-stage stand 2 and the final stand 3 are corrected and controlled by the same ratio based on the output of the control amount calculation device 22.

In the embodiment shown in FIGS. 1 and 2, in order to control the tension between the stands, the final pre-stand lowering position correction device 2
3 or the roll speed correction device 27, it goes without saying that both the final front stage stand lowering position correction device 23 and the roll speed correction device 27 may be provided and used at the same time. be. Also,
A sufficient tension control effect can be obtained using either one.

Moreover, although the tension control between the final pre-stage stand 2 and the final stand 30 has been described in the above embodiment, it goes without saying that the present invention can be similarly applied to any two adjacent stands.

Effects of the Invention The effects of the invention will be explained with reference to FIGS. 3 and 4.

Figure 3 is a chart recording the finished plate thickness and the variation in tension between the fourth and fifth stands when the conventional tension control method corresponding to Figure 5 is applied to a five-stand cold rolling mill. , in the low speed range after threading is completed.

As mentioned above, it can be seen that there is a large variation in the plate thickness because the plate thickness is not controlled.

FIG. 4 is an example of application of the tension control method according to the present invention shown in FIG. 1, during steady rolling. It can be seen that both the finished plate thickness and tension are precisely controlled.

As explained above, by applying the tension control method of the present invention, it is possible to maintain high plate thickness accuracy while keeping the inter-stand tension, which is an important factor in operation, stable over the entire length of the coil.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram of a tension control device used in one embodiment of the tension control method of the present invention. FIG. 2 is a schematic diagram of a tension control device used in another embodiment of the invention. Figure 3 shows the results when applying the conventional tension control method.
This is a chart recording variations in finished plate thickness and tension. FIG. 4 is a chart recording variations in finished plate thickness and tension when the tension control method according to the present invention is applied. FIG. 5 shows the operation of a conventional tension and plate thickness control device during sheet threading. FIG. 6 shows the operation of a conventional tension and plate thickness control device during steady rolling. (Main reference numbers) ■...Rolled material, 2.Pa.Final stage stand, 3..
・Final stand 3. 4.5... Roll drive motor, 6... Thickness gauge 6.7... Tension meter, 11... Tension control device, 12... Target plate tension value, 13... Roll speed control device , 14... Plate thickness control device 14. 21... Final stage stand 2 lowering device, 22...
Tension control device, 23...Final stage stand lowering position correction device, 24.
...Final stand roll speed correction device 24.25...
Material transfer time calculation device 25, 26... Normal plate thickness control device, 27... Roll speed correction device 27,

Claims (2)

[Claims] (1) In a tension control method for a tandem rolling mill configured with two or more stands, the tension between the nth stand and the upstream (n-1)th stand adjacent thereto is detected, and the tension is detected. calculating the deviation between the value and the target tension, and performing a proportional integral operation on the tension deviation in order to eliminate the tension deviation, and successively adjusting the roll speed of the (n-1)th stand and the nth stand based on the calculation result. Based on the above calculation result, the nth
1. A tension control method for a tandem rolling mill, comprising: modifying the roll speed of the n-stand in order to eliminate plate thickness variation on the exit side of the stand. (2) In a tension control method for a tandem rolling mill configured with two or more stands, the tension between the nth stand and the upstream (n-1)th stand adjacent thereto is detected, and the tension is detected. Calculating the deviation between the value and the target tension and performing a proportional-integral calculation to eliminate the tension deviation; Correcting the lowering position of the (n-1)th stand based on the calculation result; Based on the calculation result above. A method for controlling tension in a tandem rolling mill, comprising: correcting the roll speed of the n-stand in order to zero the plate thickness variation on the outlet side of the n-th stand due to the correction of the rolling position.