JPH0575483B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to a tension control method for a continuous rolling mill.

(Prior Art) The tension (including compressive force) generated between stands during continuous rolling must be reduced as much as possible.
For this reason, feedback control is generally performed by detecting the tension between the stands, but in the case of continuous rolling, such as shape steel rolling, where conventional tension detectors cannot be used, special measures are taken to detect the tension. That is,
Between tension, rolling load, and rolling torque, G = 2lP + R (Tb - Tf) ... (1) G: rolling torque, l: torque arm, R: roll radius, P: rolling load, Tb: rear tension, A relational expression for Tf: forward tension is established, and this expression is used to calculate and control the tension. In other words, the rolling load when there is no tension applied to the steel rolling stand,
The rolling torque is measured, the torque arm is determined, and based on this torque arm, the change in rolling torque when biting into the next rolling stand is determined as the tension between the stands, and from the actually detected rolling load and rolling torque. A common method is to calculate the torque arm of the next stage rolling stand, by determining the torque arm from the front upstream stand torque arm, the load and torque when the stand is caught, and then calculating the tension.

(Problems to be Solved by the Invention) The conventional method is: A. The tension between the stand for which the torque arm is sought and the upstream stand must be zero. B. Calculate the torque arm while calculating the tension between other stands. There are two problems: especially when the rolling speed is high, a high-speed computing unit is required. Regarding point A, if tension control is performed between all stands, the tension at the most upstream entrance stand will always be zero and will not be a problem, but
A big problem arises when tension is to be controlled from the middle of the stand, that is, between several stands downstream.

In addition, point B is that when applied to a small-scale continuous rolling system, it is required to realize the system at a low cost at the level of a microcomputer, and the increase in calculation time requires the introduction of a high-speed calculation unit, which poses a cost problem. It turns out.

(Means for Solving Problems) The basic idea of this invention is to memorize each rolling load and rolling torque when the rear end of the steel material passes through each stand, and to make the steel material pass through the final stand. At this time, the torque arm of each stand is calculated and used to control the tension of the next steel material. This is based on the empirical fact that the torque arms of each stand roll the same steel material and are approximately equal if the rolling conditions are constant.

Therefore, when the steel material changes, or when the rolling conditions change significantly, such as changing the caliber or roll gap, rolling is first performed to determine the torque arm. In other words, in what is generally known as the current lock method, the current when the steel material is caught in a rolling stand is memorized, and the change in current in the first rolling stand when the steel material is caught in the next rolling stand is detected. In order to make the tension zero, the speed of the next rolling stand is controlled to make the tension between the stands zero, and the rolling load and rolling torque at this time are detected and the torque arm is calculated. Then, this torque arm is used to calculate the tension for the first rolling of the steel material and performs tensionless control, and the rolling load and rolling torque when the steel material passes through each stand at the rear end are used to calculate the tension for the next rolling of the steel material. Calculate the torque arm for.

Figures 1 and 2 show examples of the final four stands.
Hereinafter, the manner in which the torque arm is calculated and the tensionless control is performed using the torque arm calculated in the previous pass will be explained.

Equation (1) shown earlier holds true between the tension between rolling stands, the rolling load, and the rolling torque.
When applied to the stands and rewritten with the subscript corresponding to each stand, G ₃ = 2l ₃ P ₃ + R ₃ (T ₃₄ − T ₂₃ ) ……(2) G ₂ = 2l ₂ P ₂ + R ₂ ( T ₂₃ −T ₁₂ ) ……(3) G ₁ = 2l ₁ P ₁ + R ₁・T ₁₂ ……(4) G ₁ , G ₂ , G ₃ : Each stand rolling torque P ₁ , P ₂ , P ₃ : Each stand rolling load T ₁₂ , T ₂₃ , T ₃₄ : Each stand tension l ₁ , l ₂ , l ₃ : Each stand torque arm R ₁ , R ₂ , R ₃ : Each stand can be expressed as a roll radius. Therefore, if we now pass through the #2 stand and bite into the #1 stand, the tension T ₁₂ is not generated and the torque arm l ₁ is 2l ₁ = [G ₁ /P ₁ ] ₁ ... (5 ) Also, if you pass through #3 stand and consider #2 and #1, you can calculate T ₁₂ using torque arm l ₁ and T ₂₃ does not occur, and torque arm l ₂ is (2),
From formula (3), 2l ₂ = [G ₂ /P ₂ ] ₂ + R ₂ /R ₁ [P ₁ /P ₂ ] ₂ ([G ₁ /P ₁₂ −2l
₁ )……(6) Further pass through the #4 stand and #3, #2,
If #1 is concerned, T ₂₃ and T ₁₂ can be calculated using torque arms l ₁ and l ₂ , and since T ₃₄ has not occurred, torque arm l ₃ is calculated as (2), (3), From each formula (4), 2l ₃ = [G ₃ /P ₃ ] ₃ +R ₃ /R ₂ [P ₂ /P ₃ ] ₃ ([G ₂ /P ₂ ] ₃ −
2l ₂ ) +R ₃ /R ₁ [P ₁ /P ₃ ] ₃ ([G ₁ /P ₁ ] ₃ −2l ₁ ) ...(7) can be calculated respectively. Note that i=1 in [ ]i,
2 and 3 indicate stored data when passing through stands #2, #3, and #4, respectively.

On the other hand, the tension between the stands is calculated from equations (2), (3), and (4), using the torque arms l ₃ , l ₂ , and l ₁ as parameters: T ₃₄ = G ₃ /R ₃ +2P ₃ l ₃ /R ₃ +T ₂₃ ... …(8) T ₂₃ =G ₂ /R ₂ +2P ₂ l ₂ /R ₂ +T ₁₂ …(9) T ₁₂ =G ₁ /R ₁ +2P ₁ l ₁ /R ₁ …(10) can be expressed.

That is, the torque arms of each stand l ₃ , l ₂ ,
If l ₁ is known, the tension between the stands can be calculated from equations (8), (9), and (10), and tension-free control can be achieved by performing feedback tension control. The operation will be specifically explained below with reference to the drawings.

(Function) After a certain period of time △T has passed after the steel material is caught in the #3 stand, calculate the tension T ₃₄ between #4 and #3 from equation (8), and use this calculation result to correct the #3 stand speed. Control the tension between #4 and #3 to zero. Similarly, the steel material is held in the #2 stand, and after a certain period of time ΔT, the tension between #4 and #3 is T ₃₄ and the tension between #3 and #2 is T _23.
are calculated using equations (8) and (9), and based on these calculation results, the #3 and #2 stand speeds are corrected, tensionless control is performed with zero tension, and even after biting into the #1 stand,
Obtain the tension from equations (8), (9), and (10), and correct the speeds of stands #3, #2, and #1 so that these tensions become zero. Note that β ₁ and β ₂ are influence coefficients.

Next, we will discuss the calculation of the torque arm when passing through each stand made of this steel material. When it is detected that the rear end of the steel material has passed through the #4 stand,
Lock the speed of #3, #2, #1 stands,
And after a certain period of time, the rolling torque of each stand,
The rolling loads G ₃ , P ₃ ; G ₂ , P ₂ ; G ₁ , P ₁ are each stored. Furthermore, after a certain period of time has passed since leaving the #3 stand, the torque and load G ₂ of the #2 and #1 stands are increased.
P ₂ ; Store G ₁ and P ₁ . In addition, the time from the #4 stand coming out to the #3 stand coming out is measured, and if this is above a certain value, it is assumed that the conditions of the rolled material have changed, and the speed lock of the previous stand is released. Calculate the tension between #2 and #1 stands based on the torque arm obtained in the previous pass,
Correct the speed of #2 and #1 stands and perform tension-free control. On the other hand, if this time has not reached a certain value, it is assumed that almost stable tension-free control is being performed, and operation continues with the speed locked. In this way, rolling continues, but after passing through the subsequent #2 stand and a certain period of time has elapsed, the rolling torque, loads G ₁ and P ₁ of the #1 stand are memorized.

After the steel material has passed through all the stands, the rolling torque and load of each stand [G ₃ ,
P ₃ ; G ₂ , P ₂ ; G ₁ , P ₁ ] ₃ , [G ₂ , P ₂ ; G ₁ , P ₁ ] ₂ ,
[G ₁ , P ₁ ] Based on ₁ , calculate the torque arm from equations (5), (6), and (7). In addition, i of [G, P]i
=3, 2, 1 have the same meaning as equations (5), (6), and (7).

In the drawings, Fig. 1 is a block diagram of the tension control system, and Fig. 2 is a sequence diagram of tension control and torque arm calculation.According to the sequence diagram of Fig. 2, the tension is calculated and the torque arm is calculated. As is clear from the block diagram of FIG. 1, the calculated tension is compared with the target value, the deviation is taken, and the control calculation is performed, after which it is applied to the rear stand motor as a speed correction command.

(Effect of the invention) The rolling torque and load at the time of breaking through are memorized, and the torque arm of each stand is calculated from these memorized values.
This torque arm was used to calculate the tension of the next pass steel material, making it easy to control the tension between just a few downstream stands. Also, the calculation of the torque arm and the calculation of the tension between the stands were performed separately. This eliminates the need for a high-speed arithmetic unit and can be fully realized with a microcomputer-level system, which has an excellent effect that it can be introduced particularly in a small-scale continuous rolling system in terms of cost.

[Brief explanation of drawings]

In the drawings, FIG. 1 is a block diagram of the tension control system, and FIG. 2 is a sequence diagram of the tension control system.

Claims (1)

[Claims] 1 G = 2lP + R (Tb - Tf) established between rolling torque, rolling load and tension, G: rolling torque, l: torque arm, P: rolling load, R: roll radius, Tb: In tension control of a continuous rolling mill, where the tension is calculated and controlled using the relational expression of rear tension, Tf: front tension, when the rear end of the steel passes through the rolling stands, the speed of each rolling stand in the previous stage is locked, and the speed of each rolling stand is locked. In addition to measuring and storing the load and torque of the rolling stand, the time required to pass through the next rolling stand is also measured. If this time exceeds a preset value, the lock is released and the tension is adjusted based on the torque arm. Calculate and correct the speed, measure and store the load and torque at this time, and based on these stored values, after passing through the final rolling stand, calculate the torque arm of each rolling stand, and calculate these torques. A method for controlling tension in a continuous rolling mill, characterized in that the tension in the next pass of steel rolling is calculated by an arm, the deviation from a target value is determined, and the tension is controlled so as to reduce the deviation to zero.