JP4795148B2 - Method of controlling tension in continuous rolling mill and continuous rolling mill - Google Patents

Description

  The present invention relates to a tension control method in a continuous rolling mill and a continuous rolling mill to which this tension control method can be applied.

Conventionally, rolled materials such as thin steel plates and thin aluminum plates have been manufactured by a continuous rolling mill having a plurality of rolling stands. In the continuous rolling mill, the rolling load, roll gap, and the like in the rolling stand are controlled in order to obtain a predetermined thickness of the rolled material. In addition, a looper is provided between the rolling stands, and the rising angle of the looper so that the tension of the rolled material between the rolling stands (simply called the tension between the stands) is within a predetermined range. Was properly controlled.
Many “tension control methods” for controlling the tension between the stands have been developed.

For example, the technique disclosed in Patent Document 1 measures the height of a looper installed between rolling stands, controls the roll speed based on the difference between the actual height and the target height, and the tension between the stands. The looper current is controlled based on the difference between the actual value and the target value, and the tension is set to an appropriate value. Furthermore, while estimating the resonance frequency and damping coefficient of the looper control system, by changing the setting value of the roll speed according to this estimated value, the resonance frequency and damping coefficient are corrected to appropriate values, and the continuous rolling mill is We are aiming for stable operation.
In addition, the technique disclosed in Patent Document 2 measures an entry side plate thickness variation of the rolling stand caused by an unspecified cause by using an entry side plate thickness gauge and the like, and changes in the reverse rate of the rolling stand from the measured value. By calculating the amount, calculating the exit side plate thickness change amount for suppressing the variation amount, and applying the result to the rolling stand, the occurrence of tension variation on the rolling stand entry side is suppressed. Yes.
Japanese Patent No. 3041155 Japanese Patent No. 3451919

In recent years, demands for products from users have become stricter, for example, cost reduction. Therefore, in the rolling of thin plates, etc., it is not clearly controlled in the past, and it is adopted as a product by controlling strict tension between the stands even for the tip part of the rolled material that was not shipped as a product. Requests to do are raised from the field. Moreover, the importance of tension control at the tip of the rolled material is increasing from the viewpoint of stably rolling the rolled material tip, which is an unsteady part, and stably operating the entire continuous rolling mill.
However, the technique of Patent Document 1 is a control method that assumes only the stationary part after passing through the tip of the rolled material, and it is possible to perform tension control in the middle of the rolled material. It is difficult to suppress the tension.

The technique of Patent Document 2 is also a control method that suppresses tension fluctuations in the middle of the rolled material, and it is difficult to cope with large tension fluctuations in unsteady parts such as the tip of the rolled material. .
Therefore, in view of the above problems, the present invention provides a tension control method in a continuous rolling mill that prevents fluctuations in tension between stands at the time of passing the rolling material tip and allows stable operation, and this tension control method. An object is to provide an applicable continuous rolling mill.

In order to achieve the above object, the present invention takes the following technical means.
The inventor of the present application has repeatedly studied and studied based on a number of rolling data when performing tension control at the tip of the rolled material, that is, the unsteady portion. As a result, when performing tension control in the unsteady part, control of only the looper, for example, feedback control of the looper angle using looper current, looper torque, etc., the looper may move away from the rolled material during rolling of the unsteady part. It has been clarified that the rolling material may be pushed up more than necessary, and the continuous rolling machine as a whole performs unstable control.

Therefore, in controlling the tension at the tip of the rolled material, not only focusing on the movement of the looper but also controlling it, the control amount obtained from the moment of inertia acting on the looper (the equivalent amount of inertia of the looper) is used. In addition, the rolling stand side is controlled, and a method of stably controlling the entire rolling mill, in other words, the entire control system is adopted.
As a result, a tension control method in a continuous rolling mill comprising a plurality of rolling stands for rolling the rolled material and a looper disposed between the rolling stands, when rolling the tip of the rolled material, Estimating a looper inertia equivalent amount that is an inertia moment acting on the looper, and changing any rolling condition of the rolling stand based on the estimated looper inertia equivalent amount, at the tip of the rolled material The tension was controlled so as to be a predetermined value.

By using this tension control method, even if fluctuations in the tension between the stands at the time of passing the rolling material tip end occur, the fluctuations can be reliably prevented and the continuous rolling mill can be operated stably. Is possible.
Preferably, when controlling the tension at the tip of the rolled material to be a predetermined value, a final rolling stand provided at the most downstream of the continuous rolling mill, and a pre-stage adjacent to the upstream side of the final rolling stand. Paying attention to the rolling stand, it was arranged between the final rolling stand and the preceding rolling stand using at least one of the tension, looper angle and looper torque of the rolled material between the final rolling stand and the preceding rolling stand. The looper inertia equivalent amount of the looper may be estimated, and the roll speed and / or roll gap of the preceding rolling stand may be controlled based on the estimated looper inertia equivalent amount.

In the continuous rolling mill, it is known that the rolled material passed through the plate needs to be strictly controlled because the thickness of the rolled material becomes thinner toward the downstream side. Therefore, in the tension control method of the present invention, attention is paid to the final rolling stand and the preceding rolling stand located on the upstream side thereof. Specifically, we decided to focus on the looper provided between the final rolling stand and the preceding rolling stand.
The looper inertia equivalent amount greatly varies depending on values such as “rolling material tension”, “looper angle” that is the rising angle of the looper, and “looper torque” that is the torque generated by the drive motor provided in the looper. Therefore, the looper inertia equivalent amount is estimated using these as factors.

  In addition, in most continuous rolling mills, control is conventionally employed in which when the rolling condition of the downstream rolling stand is changed, the rolling condition of the upstream rolling stand is changed in conjunction therewith. Therefore, if the rolling conditions of the final rolling stand are changed based on the estimated looper inertia equivalent amount, the rolling conditions of the preceding rolling stand may be changed unexpectedly, and the original function of the tension control of the present invention can be improved. There is no denying the possibility that it cannot be fully demonstrated. Therefore, the roll speed and / or the roll gap of the preceding rolling stand, not the final rolling stand, is controlled based on the estimated looper inertia equivalent amount.

More preferably, one or a plurality of control gains based on the estimated looper inertia equivalent amount are prepared, and the roll speed correction amount and / or the roll gap correction amount of the preceding rolling stand are calculated using the control gain. It is good to calculate and control.
By preparing a plurality of control gains and switching them appropriately, it is possible to reliably eliminate the occurrence of a phenomenon such as insufficient control amount.
The continuous rolling mill according to the present invention includes a plurality of rolling stands for rolling a rolled material, a looper disposed between the rolling stands, and a control device for controlling the rolling stand and the looper. The control device estimates a looper inertia equivalent amount, which is an inertia moment acting on the looper when rolling the tip of the rolled material, and based on the estimated looper inertia equivalent amount, There is provided a tension correcting means for changing any of the rolling conditions to control the tension at the tip of the rolled material to be a predetermined value.
The most preferable means of the tension control method in the continuous rolling mill according to the present invention is a tension control method in a continuous rolling mill provided with a plurality of rolling stands for rolling the rolled material and a looper disposed between the rolling stands. In order to control the tension at the tip when the tip of the rolled material is rolled, a final rolling stand provided at the most downstream of the continuous rolling mill and adjacent to the upstream side of the final rolling stand Focusing on the pre-rolling stand, it is arranged between the final rolling stand and the pre-rolling stand using at least one of the tension, looper angle, and looper torque of the rolled material between the final rolling stand and the pre-rolling stand. A looper inertia equivalent amount that is an inertia moment acting on the looper, and based on the estimated looper inertia equivalent amount, It is to control the roll speed and / or roll gap. At that time, one or more control gains based on the estimated looper inertia equivalent amount are prepared, and the roll speed correction amount and / or the roll gap correction amount of the preceding rolling stand are calculated using the control gain. It is good to perform control.
The most preferable means of the continuous rolling mill according to the present invention includes a plurality of rolling stands for rolling the rolled material, a looper disposed between the rolling stands, and a control device for controlling the rolling stand and the looper. In the continuous rolling mill, the control device includes a final rolling stand provided on the most downstream side of the continuous rolling mill to control the tension at the leading end when the leading end of the rolled material is rolled, Paying attention to the preceding rolling stand adjacent to the upstream side of the final rolling stand, and using at least one of the tension of the rolled material, the looper angle, and the looper torque between the final rolling stand and the preceding rolling stand, Estimating a looper inertia equivalent amount that is a moment of inertia acting on a looper disposed between the preceding rolling stand and the estimated looper inertia equivalent amount Based on, or when the tension correcting means for controlling the roll speed and / or roll gap of the pre-stage mill stand is provided.

  By using the tension control method for a rolled material according to the present invention and the continuous rolling machine to which this tension control method is applied, fluctuations in the tension between the stands at the time of passing the rolling material tip can be prevented. Further, by appropriately controlling the tension at the tip of the rolled material, the thickness of the tip can be made appropriate, and the continuous rolling mill can be stably operated.

Hereinafter, the tension control method according to the present invention will be described with reference to the drawings, illustrating a thin continuous hot rolling mill.
A thin steel plate and a thin aluminum plate are manufactured by introducing a heated slab and a base plate into a continuous rolling mill provided with a plurality of rolling stands and continuously rolling. The rolling stand provided on the upstream side of the continuous rolling mill is a rough rolling stand, and the rolling stand provided on the downstream side is a finish rolling stand that adjusts the plate thickness and the like.
The rolled material that has exited the final rolling stand provided in the final stage is rolled to a predetermined plate thickness, plate width, and plate crown, cooled while passing through a cooling device disposed downstream in the transfer direction, and wound. It is wound up by a take-up device.

  FIG. 1 shows a plurality of rolling stands 2 arranged on the downstream side of the continuous rolling mill 1. In the description of the present embodiment, in the transfer direction of the rolling material 3, the side to be transferred (winding device 10 side) is referred to as the downstream side, and the opposite side is referred to as the upstream side. Each rolling stand 2 is provided with a pair of work rolls 4, a plurality of backup rolls 5 for backing up the work rolls 4, and a load cell for measuring a rolling load. Each rolling stand 2 is also provided with a plate speed detector for measuring the plate speed, an inlet and outlet plate thermometer, an inlet and outlet plate thickness gauge, and the like.

Between each rolling stand 2, a looper 6 capable of adjusting the tension of the rolled material 3 (sometimes simply referred to as inter-stand tension) is provided. A tension measuring means such as a torque meter is provided on the base end side of the looper 6 so that the tension between the stands can be measured.
Further, the continuous rolling mill 1 is provided with a control device 7 constituted by a process computer or the like. The control device 7 includes, for example, known plate thickness control means for adjusting the roll gap of each rolling stand 2 based on the exit side plate thickness of the final rolling stand 2 [N], or a middle portion (steady portion) of the rolled material 3. When the roll is rolled, a known roll speed control means 8 for controlling the roll speed of the rolling stand 2 using the tension value measured by the looper 6 is provided.

In addition, the control device 7 estimates and estimates the looper inertia equivalent amount (sometimes simply referred to as the inertia equivalent amount) of the looper 6 using the actual value of the tension at the tip of the rolled material 3. Based on the inertia equivalent amount of the looper 6, tension correction means 9 is provided that controls the rolling conditions of the rolling stand 2 so that the tension at the tip of the rolled material 3 becomes a predetermined value.
Next, tension control at the tip of the rolled material 3 executed by the tension correction means 9 will be described.
In the tension correction means 9, the final rolling stand 2 [N] provided on the most downstream side of the continuous rolling mill 1 and the preceding rolling stand 2 [N−1] adjacent to the upstream side of the final rolling stand 2 [N]. Paying attention, at least one of the tension, the looper angle, and the looper torque of the rolled material 3 in the final rolling stand 2 [N] to the preceding rolling stand 2 [N-1] is used, and the final rolling stand 2 [N] to the preceding rolling stand. 2 [N-1] is estimated for the inertia equivalent of the looper 6, and the roll speed and / or the roll gap of the preceding rolling stand 2 [N-1] based on the estimated inertia equivalent of the looper 6. It is intended to control.

Thereafter, the looper 6 arranged in the final rolling stand 2 [N] to the preceding rolling stand 2 [N-1] is referred to as “the looper R”, and the final rolling stand 2 [N] to the preceding rolling stand 2 [N-1]. The tension of the rolling material 3 is referred to as “inter-stand tension”.
FIG. 3 shows a flowchart of the tension control method.
First, at the beginning of the rolling process, the tip of the rolled material 3 flows from the upstream side while being rolled, and is bitten into the pre-rolling stand 2 [N-1], and after a few seconds, is bitten into the final rolling stand 2 [N]. Will be included.

At that time, after confirming that the rolling material 3 has bitten into the final rolling stand 2 [N], the looper 6 in the retracted position rises, maintains a predetermined looper angle and pushes the rolling material 3 upward, Tension is applied to the rolled material 3.
Thereafter, the actual value tfi _-1 of the inter-stand tension is measured by the looper R after, for example, "plate biting into the final rolling stand 2 [N] + T seconds" (S1).
Next, the actual value of the inter-stand tension obtained from the looper R indicates whether or not the looper R that has risen when the tip of the rolled material 3 passes through is in contact with the rolled material 3 reliably. Using tfi _-1 and a preset threshold value TH, a determination is made using equation (1) (S2).

When the expression (1) is not satisfied (when the tension between the stands is small), it is determined that the looper R and the rolled material 3 are not in contact with each other, for example, correction of the roll speed, the roll gap, etc. of the rolling stand 2 The process returns to S1 again without calculating the control correction value, which is an amount.
When the expression (1) is satisfied, it is determined that the looper R is in contact with the rolled material 3, and a control correction value for correcting the inter-stand tension is calculated. Prior to this, an inertia equivalent amount of the looper 6 is calculated in S3.
In general, with respect to the looper 6, it is known that Expression (2) is established.

D in Expression (2) is the difference between the target value and the actual value of the tension between the stands, and is considered to be a disturbance when viewed from the control system.
Based on the equation (3) derived from the equation (2), the looper inertia equivalent amount T ′ _I of the looper R is estimated.

Here, T _W is the torque due to the own weight of the rolled material 3 is located in the final rolling stand 2 [N] ~ preceding rolling stand 2 [N-1], the size and density of the rolled material 3, the rise of the looper It is calculated from the looper angle, which is a corner, and various dimensions of the looper R. T _M is the torque due to the weight of the looper R, and can be calculated using the shape, weight, looper angle, etc. of the looper 6.
T _L is the Rupatoruku, using a torque coefficient of the looper current I _L the looper R phi, it can be calculated by the formula (4).

  Next, it is determined whether the tension between the stands needs to be corrected using the inertia equivalent amount of the looper 6 estimated by the expression (3). For this determination, calculation is performed using preset threshold values α and β (S4).

When the expression (5) is not satisfied, the control correction value for tension correction is set to 0, and tension control based on the looper inertia equivalent amount is not performed.
When the expression (5) is satisfied, a control correction value is calculated (S5).
The control correction value in the case of the present embodiment is the change amount ΔV _Rt of the roll speed of the preceding rolling stand 2 [N−1], and is calculated using Expression (6) based on PI control.

The control gains G _P and G _I for calculating the roll speed change amount ΔV _Rt may be constant, and a plurality of loop gains corresponding to the inertial amount T ′ _I are prepared and matched to the range. May be changed (switched). However, even when the control gain is switched, if the looper inertia equivalent amount T ′ _I is equal to or less than a certain value, it is possible to perform very suitable control if the control gains G _P and G _I are not switched. Can do.
The roll speed change amount ΔV _Rt obtained by equation (6) is added to the roll speed command value of the preceding rolling stand 2 [N−1], and the roll speed of the preceding rolling stand 2 [N−1] is changed. (S6).

When the roll gap change amount ΔS _Rt of the pre-rolling stand 2 [N−1] is adopted as the control correction value, ΔS _Rt is calculated using Expression (7).

  After the rolling of the front end portion of the rolled material 3 is finished, the tension control may be turned off or may remain on. Even if the ON state is maintained, when rolling the middle part (steady part) of the rolled material 3, the looper inertia equivalent amount of the looper R is settled to an appropriate value and does not satisfy the formula (5). Therefore, the tension control according to the present invention does not actually work and no problem occurs.

4 to 6 show control results when the tension control method according to the present invention is applied.
The broken line in each figure shows the example when not applying the tension control method of this invention (comparative example). As can be seen from the comparative example, when the looper 6 rises with the tip of the rolled material 3 biting into the final rolling stand 2 [N], the tension between the stands rapidly rises to approximately 1.10. Accordingly, the conventional roll speed control means 8 controls to change the roll speed. In addition, since the fluctuation of the tension between the stands generated at the tip is a large value, the correction time required to correct it is also long.

On the other hand, in the embodiment shown by the solid line in FIG. 4, since the looper inertia equivalent amount is accurately calculated at the tip of the rolled material 3 and the tension is controlled based on that, the roll is rolled more quickly than in the comparative example. The correction of the speed can be started, and the correction amount of the roll speed is as small as about 1.03 in the present embodiment, compared with 1.05 in the comparative example. Along with this, the fluctuation of the tension between the stands can be reduced to about 1.03, and the fluctuation can be suppressed in a short time.
That is, by using the tension control method of the present invention, it is possible to prevent fluctuations in the tension between the stands at the time of passing the tip of the rolled material 3, and it is possible to stably operate the continuous rolling mill 1 itself.

The embodiment shown by the solid line in FIG. 5 is a control result when the control gain for correcting the roll speed of the preceding rolling stand 2 [N-1] is switched according to the value of the looper inertia equivalent amount. .
Since "fine control" such as switching the control gain according to the value of the looper inertia equivalent amount is performed, the effect of control in a short time appears compared to the case of FIG. For example, the correction of the roll speed is about 1.04 at first, but decreases to about 1.01 in a short time. Along with this, the fluctuation of the tension between the stands has decreased from 1.03 to about 1.01 in a short time.

The embodiment shown by the solid line in FIG. 6 does not correct the roll speed of the pre-rolling stand 2 [N-1], but based on the estimated looper inertia equivalent amount, the roll of the pre-rolling stand 2 [N-1]. The gap correction amount is calculated, and the tension control is performed by controlling the pre-rolling stand 2 [N-1] with the roll gap correction amount. Even in this case, by starting the correction of the roll gap amount quickly, the variation in tension can be significantly reduced in a shorter time than the comparative example.
The present invention is not limited to the above embodiment.

For example, regarding control gain switching, a plurality of control gains G _P and G _I may be prepared for each range of roll speed and roll gap, and changed according to the range.
Moreover, although the tension | tensile_strength control was performed by changing the rolling conditions of the pre-stage rolling stand 2 [N-1], it is not limited to this, It is good also considering the pre-stage rolling stand 2 [N-2] as a control object. . In that case, it is preferable to calculate the control correction value based on the information of the looper 6 positioned between the preceding rolling stand 2 [N-2] and the preceding rolling stand 2 [N-1].

It is the figure which showed the outline of the continuous rolling mill. It is a block diagram of a control apparatus. 3 is a flowchart illustrating a tension control method according to the present invention. It is a figure which shows the result (1) which controlled the continuous rolling mill using the tension control method which concerns on this invention. It is a figure which shows the result (2) which controlled the continuous rolling mill using the tension control method which concerns on this invention. It is a figure which shows the result (3) which controlled the continuous rolling mill using the tension control method which concerns on this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Continuous rolling mill 2 Rolling stand 3 Rolled material 6 Looper 7 Control apparatus 8 Roll speed control means 9 Tension correction means R The said looper

Claims (3)

A tension control method in a continuous rolling mill comprising a plurality of rolling stands for rolling a rolled material and a looper arranged between the rolling stands,
A final rolling stand provided on the most downstream side of the continuous rolling mill and a pre-rolling stand adjacent to the upstream side of the final rolling stand to control the tension at the leading end when rolling the leading end of the rolled material. Focusing on
The moment of inertia acting on the looper disposed between the final rolling stand and the preceding rolling stand using at least one of the tension, looper angle, and looper torque of the rolled material between the final rolling stand and the preceding rolling stand. Estimate a certain amount of looper inertia,
Based on the looper inertia equivalent amount the estimated tension control method in the continuous rolling mill and controlling the roll speed and / or roll gap of the front roll stand. One or a plurality of control gains based on the estimated looper inertia equivalent amount are prepared, and the control speed is used to calculate the roll speed correction amount and / or the roll gap correction amount of the pre-rolling stand. The tension control method in the continuous rolling mill according to claim 1 , wherein the tension control method is performed. In a continuous rolling mill comprising a plurality of rolling stands for rolling a rolled material, a looper arranged between the rolling stands, and a control device for controlling the rolling stand and the looper,
The control device includes a final rolling stand provided at the most downstream side of the continuous rolling mill and an upstream side of the final rolling stand so as to control a tension at the leading end when the leading end of the rolled material is rolled. Focusing on the first rolling stand adjacent to the first rolling stand, and using at least one of the tension, looper angle, and looper torque of the rolled material between the last rolling stand and the first rolling stand, between the final rolling stand and the first rolling stand. the looper inertia substantial amount of inertia moment acting on the deployed looper estimated in, on the basis of the estimated looper inertia equivalent amount, the tension correcting means for controlling the roll speed and / or roll gap of the front stage mill stand A continuous rolling mill characterized by being provided.

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