JP2978407B2 - Rolling control method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for controlling the thickness and tension of a rolled material between stands when a steel material is rolled by a tandem rolling mill.

[0002]

2. Description of the Related Art A conventional hot rolling mill includes a rolling load P and a rolling position as known, for example, as a gauge meter AGC.
From S , the plate thickness is controlled using the rolling position as an operation amount, and the peripheral speed of the work roll (hereinafter, referred to as a roll peripheral speed) and the height of the looper are changed to change the tension between stands (hereinafter, referred to as tension). ). Conventional methods include:
There are the following problems. For example, disturbances in the thickness control of the hot tandem rolling process include the following.

(1) Skid mark disturbance: Disturbance caused by uneven temperature in the longitudinal direction of the steel sheet. Even when there is no thickness deviation in the steel sheet, the deformation resistance fluctuates depending on the level of the temperature and becomes a factor of the output side sheet thickness deviation. . In the case where the rolling control corresponding to the deformation resistance is not performed, if the temperature is increased by the skid mark, the rolling load p decreases, and the exit side plate thickness h decreases. The frequency of the skid mark disturbance is relatively slow, about 1 [rad / s].

(2) Roll eccentric disturbance: Disturbance caused by fluctuation of the roll gap due to eccentricity of the backup roll. When the rolling control corresponding to the eccentricity is not performed, if the roll gap is opened due to the eccentricity of the roll, the rolling load P decreases, and the exit side plate thickness h increases.
The frequency of the roll eccentric disturbance is proportional to the number of rotations of the backup roll, and becomes higher at a later stage, and is about 20 to 60 [rad / s] in the # 7 stand.

[0005] (3) Disturbance of thickness deviation on the incoming side: The part where the thickness deviation on the outgoing side occurs in the preceding rolling mill becomes a disturbance at the time of rolling at the next stage. This is the input side thickness deviation disturbance. When the rolling-down control corresponding to the entry-side sheet thickness deviation is not performed, if the entry-side sheet thickness of the steel sheet decreases, the rolling load P decreases, and the exit-side sheet thickness h decreases. Here, the entrance side thickness deviation can be measured in advance by a measuring device between stands.

In the conventional sheet thickness control, a change in the sheet thickness is estimated by measuring the rolling load P. Regarding the roll eccentric disturbance, since the exit sheet thickness and the direction of the change in the rolling load are opposite, There is a problem that, when trying to remove the entrance side sheet thickness deviation disturbance or the skid mark disturbance, the influence of the roll eccentric disturbance appears on the exit side sheet thickness.

On the other hand, in the cold rolling process, a method of controlling the tension by changing the rolling position and controlling the thickness by the peripheral speed of the roll is widely used. Regarding the use of this method in a hot rolling mill, the inventors disclosed in Japanese Patent Laid-Open No.
No. 6,418,418. JP-A-5-26
The method disclosed in Japanese Patent Publication No. 1418 will be described with reference to FIG.
Steel plate tension between i and i + 1 stands (hereinafter referred to as tension)
T (i) is detected by a tensiometer (indicated by a circle in the figure) and detected as a difference ΔT (i) from a tension reference value. The tension controller TC (i) calculates the _rolling position change amount ΔS _ref1 (i + 1) of the (i + 1) th stand for making the tension deviation ΔT (i) substantially zero, and accordingly, the rolling position driving means of the (i + 1) th stand To change the rolling position. Since the direction of the tension change with respect to the exit side plate thickness change is the same direction for both causes of the roll eccentricity and the skid mark, it is possible in principle to remove these effects simultaneously by controlling the tension to be constant by reducing the tension. .
With respect to the i + 1 stand entry side thickness deviation disturbance, the i + 1 stand entry side thickness h (i) is measured with an X-ray thickness gauge (▽ in the figure), and the speed v (i ) Is measured by a speedometer (marked with □ in the figure). The sheet thickness control device HC (i) obtains a time t (i +) at which the difference occurs in the i + 1 stand based on the detected sheet thickness h (i) and the speed v (i) of the rolled material in the difference. 1), amount of change in rolling position Δ to eliminate thickness deviation
S _ref2 (i + 1) and the roll peripheral speed change amount ΔVR (i) of the i-stand for removing the tension deviation generated when the reduction position change amount is changed are calculated at t (i + 1). The roll position change amount ΔS _ref2 (i + 1) and the roll peripheral speed change amount ΔVR (i) are calculated by i +
The disturbance at the entrance side thickness deviation is suppressed by simultaneously changing the rolling position driving means of one stand and the roll peripheral speed changing means of the i stand.

[0008]

However, the above method (Japanese Patent Application Laid-Open No. 5-261418) has the following problems. That is, in order to remove the thickness variation due to both the roll eccentricity and the deformation resistance variation in the tension control, the tension control system is required to have an extremely high response (50 to 70 rad / s). Tension measurement requires a complicated calculation and requires a long calculation time, and it is difficult to extend the response of the tension control system to a band necessary for removing a thickness deviation due to roll eccentricity due to tension detection noise. In this case, the effect of the low frequency skid mark (1-2 rad / s) can be removed, but the effect of the roll eccentricity (20-60) which becomes a high-frequency disturbance.
rad / s) cannot be removed.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has a relatively low response tension control system (10 to 3).
Even at 0 rad / s), the effect of roll eccentricity is reduced by controlling the rolling load.

[0010]

SUMMARY OF THE INVENTION The present invention measures the tension T (i) of a rolled material between an i-th stand and an (i + 1) -th stand and obtains a difference ΔT between a detected tension T (i) and a target tension T _ref (i). In order to make (i) substantially zero, the rolling position of the (i + 1) th stand is changed, and i + 1 due to the deviation Δh (i) of the detected thickness h (i) from the target thickness h _o (i) at the i-stand exit side. In order to reduce the thickness deviation on the stand exit side, i is determined based on the rolled material speed v (i).
Change the rolling position of the +1 stand and the roll peripheral speed of the i stand, the mass per unit time of the rolled material entering between the adjacent stands of the tandem rolling mill and the mass per unit time of the rolled material exiting between the stands are equal. In the rolling control method of controlling the rolling position and the roll peripheral speed so that the rolling position of the i + 1 stand is changed, ΔT (i),
From Δh (i) and v (i), target rolling load P for i + 1 stand
_ref (i + 1) is calculated, and the rolling position change amount ΔS (i + 1) is calculated so that this P _ref (i + 1) matches the detected rolling load P (i + 1) of the i + 1 stand. In this method, the pressing position of the stand is corrected by the pressing drive means of the i + 1 stand.

[0011]

The details of the present invention will be described with reference to FIG. In FIG. 1, HC (i) is a thickness control device, TC (i) is a tension control device, and PC (i + 1) is a rolling load control device. Each stand is equipped with a drive motor M, a rolling load detector, a rolling position detector, and a rolling drive device. Between each stand, there is an X-ray plate thickness gauge, a rolling material tension meter, and a rolling material speedometer. doing. Rolling load detector is rolling load P (i + 1)
The X-ray thickness gauge detects the thickness h (i) of the rolled material, the tension meter detects the tension T (i) of the rolled material, and the speedometer detects the speed v (i) of the rolled material.

The skid mark disturbance is a relatively low frequency disturbance, which is suppressed by controlling the tension between stands. Since the rolled material does not stay between the rolls of the rolling mill,
Since the mass of the rolled material per unit time entering the roll bite of the i + 1 stand (hereinafter referred to as mass flow) is equal to the mass of the rolled material per unit time leaving the roll bite, h (i + 1) × v (i +1) × b (i + 1) = H (i + 1) × V (i + 1) × B (i + 1) (1) Here, h (i + 1): i + 1 stand exit side plate thickness [mm] v (i + 1): i + 1 stand exit side plate speed [mm / s] b (i + 1): i + 1 stand Outer side plate width [mm] H (i + 1): i + 1 Stand entrance side plate thickness [mm] V (i + 1): i + 1 Stand entrance side plate speed [mm / s] B (i + 1): i +1 Stand exit side plate width [mm].

Output side thickness h (i + 1) in the i + 1 stand
Is changed, it appears as a change in the entrance speed V (i + 1) according to the equation (1). as a result,

[0014]

(Equation 2)

Where T (i): tension between i and i + 1 stand [kgf / mm ² ] E: Young's modulus of rolled material [kgf / mm ² ] L: distance between i and i + 1 stand [mm] As shown in FIG.
This change in tension is detected by a tension meter (indicated by 〇 in the figure) and input to a tension controller TC (i). The tension controller TC (i)
Rolling load standard change amount ΔP _ref1
By calculating (i + 1) and indirectly changing the rolling position through the rolling load control system, the thickness variation of the i + 1 stand exit side plate thickness caused by the skid mark disturbance is suppressed. Since the frequency of the skid mark is relatively low, the response of the tension control may be relatively low.

The roll eccentric disturbance is a relatively high-frequency disturbance, which is suppressed by high-speed rolling load control. Specifically, the rolling position change amount ΔS (i + 1) of the (i + 1) -th stand is set so that the detected rolling load value P (i + 1) of the (i + 1) _-th stand matches the command value P _ref1 (i + 1). Control device PC (i + 1)
And the rolling position of the i + 1 stand is changed.
As the rolling load control device PC (i + 1), for example, a PID system
I use it. Roll eccentric disturbance of i + 1 stand is i + 1
Although detected as a change in the rolling load P (i + 1) of the stand, the rolling load fluctuation is suppressed by the rolling load control device PC (i + 1). In other words, it has the effect of suppressing roll gap fluctuations due to roll eccentricity, and reduces plate thickness deviation.

The thickness deviation at the i + 1 stand entrance side is measured by an X-ray thickness gauge (▽ in the figure). If the deviation is not substantially zero, the speed v (i) of the rolled material in the portion where the deviation occurs is measured. The speed is measured by a speedometer (marked with □ in the figure). Based on the detected plate thickness h (i) and the speed v (i) of the rolled material in the portion where the deviation occurs, the sheet thickness control device HC (i) determines the time t (i + 1) at which the deviation occurs in the i + 1 stand. ), The rolling load command change amount ΔP _ref2 (i + 1) for removing the sheet thickness deviation, and the roll peripheral speed change amount of the i stand for removing the tension deviation generated when the rolling load command change amount is changed. ΔVR (i) is calculated, and at t (i + 1), the rolling load change amount ΔP _ref2 (i + 1) and the roll peripheral speed change amount ΔVR (i)
Are simultaneously changed by the rolling load control system of the i + 1 stand and the roll peripheral speed changing means of the i stand.

[0018]

FIG. 1 shows the configuration of a rolling mill for implementing the present invention in one embodiment. The following numerical values are examples when the present invention is implemented between 6 and 7 stands, that is, when i = 6.

(1) Measure the plate thickness on the i + 1 stand entrance side,
If the deviation is substantially zero, the tension controller TC
(i) calculates the change amount ΔP _ref1 (i + 1) of the rolling load target value from the difference ΔT (i) between the tension T (i) and the target tension T _ref (i + 1).
For example, when the calculation time interval is 20 [ms], the following equation is used.

ΔP _ref1 (i + 1) [K] = ΔP _ref1 (i + 1) [K−1] −21000ΔT (i) [K−1] + 14000ΔT (i) [K] (3) Here Where the subscript [K] represents the detected value or calculated value at time K, and it is assumed that K advances by one every 20 [ms].
The change amount ΔP _ref1 (i + 1) [K-1] of the rolling load target value at the previous time is
1000 [kgf], the difference ΔT (i) [K-
1] is 0.1 [kgf / mm ² ], the detected tension T (i) at the current time
[K] is 0.9 [kgf / mm ² ] and the target tension value T _ref (i) is 1.0 [kgf / mm ² ].
/ mm ² ], the tension T (i) at the current time and the target tension T _ref (i)
The difference ΔT (i) [K] is: ΔT (i) [K] = T _ref (i) −T (i) [K] = 1.0−0.9 = 0.1 [kgf / mm ² ] (3a) From this, the change amount of the rolling load target value at the current time Δ
P _ref1 (i + 1) [K] becomes ΔP _ref1 (i + 1) [K] = 1000−21000 × 0.1 + 14000 × 0.1 = 300 [kgf] (3b).

This rolling load target value change amount ΔP _ref1 (i + 1)
The sum of the rolling load set value P ₀ (i + 1) and the rolling load target value P
_ref (i + 1) is input to the rolling load control device PC (i + 1). Rolling load set value P ₀ (i + 1) [k] at the current time is 500 × 10
^In the case of ³ [kgf], the rolling load target value P _ref (i + 1) at the current time
[K] is represented by P _ref1 (i + 1) [K] = 500,000 + 300 = 500,300 [kgf] (4).

The rolling load control device PC (i + 1) calculates a difference ΔP (i +) between the rolling load target value P _ref (i + 1) and the detected rolling load P (i + 1).
From 1), the roll-down position change amount ΔS (i + 1) that makes this difference zero is calculated, and the roll-down position change means of the (i + 1) th stand calculates i +
Change the pressing position of one stand. Reduction position change amount ΔS
To calculate (i + 1), for example, ΔS (i + 1) [K] = ΔS (i + 1) [K-1] + 2.6 × (1/10 ⁶ ) × ΔP (i + 1) [K ] −2 × (1/10 ⁷ ) ΔP (i + 1) [K−1] (5) Reduction position change amount ΔS (i + 1) [K-1] at the previous time
Is 0.01 [mm], and the difference ΔP (i + 1) [K-1] between the rolling load target value at the previous time and the detected rolling load is 1000 [kgf],
The detected rolling load P (i) [k] at the current time is 500 × 10 ³ [kg
f], the rolling position change amount ΔS (i + 1) [k] at the current time
From the value of equation (4), ΔS (i + 1) [K] = 0.01 + 2.6 × (1/10 ⁶ ) × (500300-500000) −2 × (1/10 ⁷ ) × 1000 = 0.01058 [ mm] (5a), and the rolling position of the i + 1 stand is set to 0.01058 [mm].
Operates in the closing direction.

Thus, the roll eccentric disturbance is suppressed by the rolling load control, and the skid mark disturbance is suppressed by the tension control. Therefore, even when the response of the tension control is insufficient to eliminate the roll eccentric disturbance, the roll eccentric disturbance can be suppressed.

(2) The thickness deviation on the i + 1 stand entrance side was measured with an X-ray thickness gauge (triangular mark in the figure), and when the deviation was not substantially zero, a deviation occurred with the detected plate thickness h (i). A speedometer (square mark in the figure) measures the speed v (i) of the rolled material in the portion. The sheet thickness control device HC (i) determines that the part having the deviation is i + based on the detected sheet thickness h (i) and the speed v (i) of the rolled material in the part having the deviation.
At time t (i + 1) at which one stand is engaged, the rolling load command change amount ΔP _ref2 (i + 1) for removing the thickness deviation and the tension deviation generated when the rolling load command change amount is changed are removed. Then, the roll peripheral speed change amount ΔVR (i) of the i-stand is calculated. For calculating the rolling load command change amount ΔP _ref2 (i + 1), for example, ΔP _ref2 (i + 1) = 1.11 × 10 ⁶ [h ₀ (i) −h (i)] (6) is used. . Here, h ₀ (i) is a thickness reference value. When the sheet thickness is detected as 3.01 [mm] with respect to the sheet thickness reference value of 3.00 [mm], the rolling load command change amount ΔP _ref2 (i + 1) becomes ΔP _ref2 (i + 1) = 1.11 × 10 ⁶ (3.01−3.00) = 1.11 × 10 ⁴ [kgf] (6a)

For calculating the roll peripheral speed change amount ΔVR (i), for example, ΔVR (i) = − 2000 [h ₀ (i) −h (i)] (7) is used. For the above thickness deviation, the roll peripheral speed change amount ΔV
R (i) is as follows: ΔVR (i) = − 2000 (3.01-3.00) = − 20 [mm / s] (7a)

When the rolled material travels and reaches time t (i + 1), the rolling load target value ΔP _ref (i + 1) is changed to the rolling load change amount ΔP
increase by _ref2 (i + 1), that is, 1.11 × 10 ⁴ [kgf],
It is input to the rolling load controller PC (i + 1) to change the rolling position of the i + 1 stand via the rolling load controller PC (i + 1), and at the same time, the roll peripheral speed of the i stand is changed by the roll peripheral speed change amount ΔVR (i) Change by minute, ie, -20 [mm / s].

This suppresses a variation in tension and a variation in thickness at the outlet side when a variation in the thickness of the entrance side is applied to the i + 1 stand.

When the fundamental wave frequency of 2.18 Hz and the amplitude of 32 μm are given as the roll eccentric disturbance of the # 7 stand, the roll eccentric disturbance appears in the tension and the plate thickness as shown in FIG. In the case where the control of the embodiment is performed, the roll eccentric disturbance is suppressed as shown in FIG.

[0029]

As is apparent from the above description, according to the present invention, even when the response of the tension control is slower than the roll eccentric disturbance, the roll eccentric disturbance is suppressed, and the thickness deviation is reduced. In addition, it suppresses fluctuation in tension due to roll eccentric disturbance.

[Brief description of the drawings]

FIG. 1 is a block diagram of a tandem rolling mill that embodies the present invention in one embodiment.

FIG. 2 is a graph showing thickness fluctuation and tension fluctuation when the present invention is implemented.

FIG. 3 is a block diagram of a conventional tandem rolling mill that controls tension at a rolling position.

FIG. 4 is a graph showing sheet thickness fluctuation and tension fluctuation of a conventional tandem rolling mill that controls tension at a rolling position.

[Explanation of symbols]

 TC (i): tension control device PC (i + 1): rolling load control device HC (i): plate thickness control device

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B21B 37/16-37/20 B21B 37/48 B21B 37/66

Claims (1)

(57) [Claims] 1. A tension T (i) of a rolled material between an i-th stand and an (i + 1) -th stand is measured, and a difference ΔT (i) between a detected tension T (i) and a target tension T _ref (i) is set to substantially zero. I + 1
In order to reduce the plate thickness deviation on the exit side of the i + 1 stand due to the deviation Δh (i) of the detected plate thickness h (i) from the target plate thickness h _o (i) on the exit side of the stand i by changing the rolling position of the stand. Changing the rolling position of the i + 1 stand and the peripheral speed of the i-stand based on the rolled material speed v (i), the mass per unit time of the rolled material entering between adjacent stands of the tandem rolling mill and the distance between the stands. In a rolling control method for controlling the rolling position and the roll peripheral speed so that the mass per unit time of the rolled material to be output is equal, ΔT (i), Δh for changing the rolling position of the i + 1 stand
(i) and v (i), the i + 1 rolling load target value P _ref (i + 1) is calculated, and this P _ref (i + 1) and the detected rolling load P of the i + 1 stand are calculated.
a rolling control method, wherein a reduction position change amount ΔS (i + 1) is calculated so that (i + 1) coincides, and the reduction position of the stand is corrected by the reduction driving means of the i + 1 stand. .