JPH0573484B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to tension control in a continuous rolling mill, and particularly to a method based on torque arm calculation.

(Prior Art) The tension (including compressive force) generated between stands during continuous rolling must be reduced as much as possible.
For this reason, feedback tension control is normally performed by detecting the tension between the stands, but in cases where a general tension detector cannot be used, such as when rolling a section steel, special measures are taken to detect the tension.

That is, in continuous rolling, the relationship between tension, rolling load, and rolling torque is G = 2lP + R (Tb - Tf) ... (1) G: rolling torque, l: torque arm, P: rolling load, R: roll radius, A relational expression exists between Tb: rear tension and Tf: front tension, and this expression is used to calculate and control the tension. In other words, the rolling torque and rolling load are detected when there is no tension when the steel material is caught in the most upstream rolling stand, the torque arm is determined from these detected values, and the rolling torque when the steel material is drawn into the next rolling stand is determined. , the change in load is calculated as the tension between the stands based on the previously determined torque arm, and then the torque arm of the next rolling stand is determined from the rolling torque and rolling load obtained through actual measurements. Based on this, the tension between the stands, the torque arm of the next rolling stand, and the torque arm of each downstream rolling stand are calculated sequentially as the rolling stand is inserted into the downstream rolling stand.

(Problem to be solved by the invention) In the conventional method, the torque arm is determined from the load and torque when the steel material is rolled into a rolling stand. The tension between the two must be zero.

This does not pose a problem if tension-free control is performed between all stands, as there is always tension-free at the entrance of the most upstream stand, but if tension-free control is performed from the middle of the stand, it is difficult to determine the torque arm. For this purpose, the tension between the stands immediately before and upstream had to be reduced to zero, which was impossible with conventional methods.

(Means for Solving the Problems) This invention stores the current when the tip of the steel material gets caught in the immediately upstream stand when performing tensionless control from the middle of the stand, and then applies it to the subsequent downstream stand. The tension is reduced to zero using the so-called current lock method, which detects the current change in the above-mentioned immediately upstream stand when it is jammed, and controls the speed of the downstream stand so as to reduce this to zero, thereby making the tension between it and the immediately preceding upstream stand zero. control is performed between the tip stand of multiple stands that require tension control and the immediately preceding upstream stand, and the conventional method of determining the torque arm when steel material is bitten is applied between subsequent stands. shall be.

FIG. 1 shows an example in which three stands in the middle of the stands are controlled without tension. Equation (1) above holds true between the tension between the rolling stands, the rolling load, and the rolling torque, but if we apply this to the stand in the example and rewrite it by adding a subscript corresponding to each stand, we get , 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: Rolling torque, P: Rolling load, T: Tension l: Torque arm, R: Roll radius. Therefore, if we now try to use the conventional method of calculating the tension by calculating the torque arm during biting between the three stands #3, #2, and #1, the tension between it and the immediately preceding upstream stand #4 will be zero. Must. In other words, when the steel material is pushed into #3 stand, if the tension T ₃₄ between it and #4 stand is zero,
It has not yet entered the #2 stand and the tension is T _23.
has not occurred, so the torque arm l ₃ is 2l ₃ = [G ₃ /P ₃ ] ₃ ...(5) Next, when it bites into the #2 stand, the tension T ₂₃ is calculated using the torque arm l ₃ . I/R ₃・[P ₃ ] ₂ (2l ₃ − [G ₃
/P ₃ ] ₂ ), torque arm l ₂ is 2l ₂ = [G ₂ /P ₂ ] ₂ +R ₂ /R ₃ [P ₃ /P ₂ ] ₂ ([G ₃ /P ₃ ] ₂
−2l ₃ ) ...(6) When the #1 stand is further bitten, _{the tension T 12 is} reduced to I/R _{2 ・}[P ₂ ] ₁ (2l ₂ −[G ₂ /P ₂ ] ₁ ) + T ₂₃ , and the torque arm l ₁ is calculated as 2l ₁ = [G ₁ /P ₁ ] ₁ +R ₁ /R ₂ [P ₂ /P ₁ ] ₁ ([G ₂ /P ₂
] ₁ +2l ₂ ) +R ₁ /R ₃ [P ₃ /P ₁ ] ₁ ([G ₃ /P ₃ ] ₁ +2l ₃ )
......(7) can be calculated respectively. Note that i=
3.2.1 shows the detected values when biting into #3, #2, and #1, respectively.

If the torque arm is determined, the tension between the stands is (2),
From equations (3) and (4), using 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 It can be expressed as 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). i.e. torque arm
If l ₃ , l ₂ , and l ₁ are known, the tension between the stands can be calculated from equations (8), (9), and (10), and tension-free feedback control can be realized.

In the above-mentioned torque arm calculation method when the steel material is bitten into the rolling stand, the present invention applies a current lock method to make the tension between the steel material and the immediately upstream stand, which is T ₃₄ in the embodiment, zero. This is what I did. The operation will be explained below with reference to the drawings.

(Function) In Figure 1, #3, #2, in the middle of the stand,
In order to control the tension between the #1 stands, it is necessary to reduce the tension to zero between the #4 stand immediately upstream. That is, after a certain period of time has elapsed since the steel material was bitten into the #4 stand (this is to avoid transient phenomena such as impact drops), the current of the motor of the #4 stand is detected and stored. Subsequently, after a certain period of time has elapsed until the steel material is caught in the #3 stand and stabilized as described above, the motor current of the previous #4 stand is detected, compared with the memorized current value, and the deviation is determined.

This current deviation signal is PI amplified and used as a speed correction command for the #3 stand motor, and the #3 stand speed is increased or decreased in order to reduce this current deviation. As a result, if the current deviation decreases and becomes smaller than a predetermined value, a speed lock command is issued to lock the speed of #3 stand, and a calculation command for #3 stand/torque arm is issued, and the rolling torque and rolling Calculate the torque arm from the load. Hereinafter, the torque arm of each stand #2 and #1 engages the stand #2 and #1 of the steel material and detects and determines the rolling torque and rolling load after a certain period of time has elapsed. Note that CP in the drawing is a circuit that determines whether the current deviation is below a certain value, and #2 is the sequence control unit.
In order to calculate the torque arm of the #1 stand, a calculation command is output to the stand torque arm calculating device of each of #2 and #1 from the biting timing signal of the #2 and #1 stands of the steel material.

(Effects of the Invention) This invention provides a method for calculating tension by determining the torque arm from the load and torque at the time of biting during continuous rolling. is adjusted to zero by applying a current lock method, and the torque arm calculation method at the time of biting can be used from any point in the stand, and the conventional tension-free control over the entire rolling stand is performed. , load and torque detectors, torque arm calculation calculators, etc. must be installed on every rolling stand, the number of equipment items and calculation processing time can be significantly reduced, resulting in cost reductions. This is a major contribution.

[Brief explanation of the drawing]

FIG. 1 is a sequence and block diagram for controlling the tension between three stands.

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: backward Tension, Tf: In tension control of a continuous rolling mill where the tension is calculated and controlled using the relational expression of forward tension, the current in the stand immediately before the upstream stand when the tip of the steel material is bitten by the stand immediately before the upstream of the tension control stand group. is memorized, and when it bites into the next downstream stand, which is the tip stand of the tension control stand group, the current change in the immediately preceding upstream stand is detected, and the speed of the following downstream stand is controlled so as to reduce this to zero. By making the current in the immediately upstream stand the same before and after the tip of the steel material bites into the downstream stand, the tension between the downstream stand and the immediately upstream stand is made zero, and the current The load and torque of the downstream stand are determined and the torque arm is calculated. Based on this torque arm, each stand torque arm of the downstream tension control stand group is sequentially determined. Based on these torque arms, the tension is calculated and the difference between it and the target value is calculated. A tension control method for a continuous rolling mill, characterized in that the tension is controlled so that the deviation is determined and the deviation is made zero.