JPH0515918A - Controller for tension between stands of hot tandem rolling mill - Google Patents

Abstract

PURPOSE:To prevent a resonance from being generated by executing controlling draft positions to make the tension of a material to be rolled constant and controlling the circumferential speeds of rolls to make the height of a looper constant alternately on every other stand. CONSTITUTION:When an variation of tension of the material 1 to be rolled is generated between an (i)-th stand and a (i+1)-th stand, the rolling reduction Si+1 of the rolls of the (i+1)-th stand is corrected by the restraining operation of a 1st tension controlling means to keep the tension of the material to be rolled constant. A disturbance of tension is generated between adjacent (i+1)-th stand and (i+2)-th stand with this operation. This disturbance of tension is absorbed by changing the height of the looper. The circumferential speed V(i+1) of the roll is changed so that the 2nd tension control means returns the height of the looper to a prescribed position. Though rolling down operations are carried out to variation of tension, the tension can be controlled stably and at high speed, without generating resonance, a high accuracy of a plate thickness and improvement of shape are obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot tandem rolling mill, and more particularly to a device for controlling tension between stands of a hot tandem rolling mill.

[0002]

2. Description of the Related Art In a tandem hot rolling mill, the tension between stands affects the rolled sheet thickness. Therefore, conventionally, a looper is arranged between the stands, and the tension between the stands is kept constant by this looper. FIG. 6 shows an example of the tandem finish rolling mill. The looper is driven by the electric motor IM. Looper height controller H. C and the looper tension controller ensure that the height of the looper is within the set range and the tension between the strip stands is stabilized at the target value IM.
Torque (current) is controlled. The rolled plate thickness of the strip is controlled by the feedforward plate thickness control function F. F and automatic plate pressure control function AGC. SR connected to the block of AGC in FIG. 6 is a reduction Leonard, SM is a reduction electric motor,
S0 is a roll gap detector, LC is a rolling load meter, and F1 to F7 are stands. The rolling roll of each stand is rotatably driven by the roll driving motor M, and this speed is controlled by the main machine Leonard SR. SAC stands for Successive or Mass Flow Control Input.

The response of the looper (several rad / sec) and the response of the rolling speed (speed by M) (tens of rad / sec) are the response of the hydraulic pressure reduction position control device (SR + SM) that determines the roll opening. Since it is significantly lower than the performance (hundreds of tens of rad / sec), the response speed of the looper to changes in tension between stands due to changes in the rolling position (roll opening) is low, and tension fluctuations caused by changes in rolling are sufficient. I can't control it. As a result, the flatness may be poor in the rolling of a thin material or the like, and the effect of AGC (automatic plate thickness control) is reduced. For example, when the plate thickness deviates in the larger direction and the AGC lowers the rolling down in response to this, the tension is relaxed, and the decrease in tension acts in the direction of increasing the plate thickness, so the effect of AGC is suppressed. .. In cold rolling, tension fluctuation is suppressed by controlling the rolling position (roll opening). This conventional example is shown in FIG. 7, and FIG. 8 shows the rolling control function of the rolling equipment shown in FIG. In this example, the plate thickness control by reduction is performed in the # 1 stand, and the plate thickness is determined by the roll peripheral speed (roll peripheral speed ratio between stands) in the # 2 to # 4 stands. When the tension between stands changes and goes out of the allowable range, the tension is returned to the allowable range by rolling down (tension limit control by rolling down). # 4-5 A tension monitor AGC (plate thickness control by roll peripheral speed ratio control between stands) is performed between the stands. In FIG. 7, APC is a rolling position control device, ATC is a tension control function, and ASR is a plate thickness control function by roll peripheral speed ratio control. The contents of these control functions are shown in FIG.

When the plate thickness is determined by the roll peripheral speed ratio between the stands, the plate thickness is controlled by the roll peripheral speed ratio control, and the inter-stand tension is controlled by the rolling reduction, the responsiveness of the hydraulic pressure reduction position control device is high. Tension control with high responsiveness that sufficiently absorbs tension changes due to changes in peripheral speed is realized.

[0005]

However, the change in the reduction due to the tension control of the i stand is due to the forward tension Δσi- (i +
1) and rearward tension Δσi- (i-1). These changes induce changes in tension-controlled reduction at the i + 1 and i-1 stands, which cause changes in the anterior and posterior tensions. That is, it induces a further change in the rolling reduction due to the tension control in the i-stand.
In this way, the tension control interacts between the stands and the tension control oscillates.

In the case of cold rolling, when the reduction is operated, the backward tension changes greatly, but the forward tension does not change so much, and therefore such a problem is not significant. However, in the case of hot rolling, the change in the front tension is large, and the above-mentioned problems are likely to occur. The rolling behavior inherent in this type of problem will be described in more detail. In the hot tandem rolling shown in FIG.
The functional configuration of the rolling stand in the case where the strip thickness is determined by the roll peripheral speed ratio between the stands, the strip thickness is controlled by the roll peripheral speed ratio control, and the inter-stand tension is controlled by the rolling reduction is shown. Figure 8
The symbols shown in and the symbols shown below mean the following items. M: Mill rigidity coefficient Q: Plasticity coefficient R: Flat roll diameter γ: Rolling ratio f: Advanced ratio H: Inlet plate thickness h: Outlet plate thickness V: Inlet plate speed v: Outlet plate speed T: Rear tension (in Side tension) S: Reduction position (the direction in which the reduction is made is-). (1) Detect the tension deviation (tension looseness: ΔT1−) behind # 2 stand (on the input side). (2) The tension control system C2 for reduction raises the reduction position (Δ
S2 +). (3) As a result, the outlet plate thickness increases (Δh2 +). (4) The rolling reduction γ decreases and the advance rate f decreases (Δ
f2-). In cold rolling, Δf2 is almost zero. γ =
(H−h) / H, f = func. (Γ, μ, R). (5) Since the roll peripheral speed is constant, the outlet plate speed decreases (Δv2-). (6) Due to the above (3) and (5), the entry side plate speed is increased (ΔV2
+). (7) # 1 stand exit side plate speed does not change (Δv1 =
0). (8) From the above (6) and (7), # 2 stand rear tension = # 1 stand front tension is increased (ΔT1 +).

Up to this point, the deviation of the # 2 stand rear tension is absorbed. In the case of cold rolling, since the coefficient B2 is small, the effect of tension control by rolling does not significantly affect the downstream stand. However, hot rolling causes the following problems. (9) No change in plate speed on the # 3 stand entry side (ΔV2 = 0). (10) Due to the above (5) and (9), # 2 stand front tension = # 3 stand rear tension is increased (ΔT2 +). If a tension control system by rolling down is introduced to only a single stand, the change is up to this point. Hereinafter, the case where the tension control system by the rolling is introduced to all the stands will be described. (11) Upon detecting the change in (10) above, the tension control system (C3) of the # 3 stand lowers the reduction position (ΔS3−). (12) The reverse control of (3) to (8) above is performed, and the # 3 stand rear tension = # 2 stand front tension relaxes (ΔT2-). (13) Due to (12) above, the # 2 stand outlet side plate thickness increases (further) (Δh2 ++). (14) Similar to (3) to (8) above, # 2 stand rear tension =
# 1 Stand front tension is (more) increased (ΔT1 ++). In this way, the tension control by reduction is over-controlled,
The tension control system oscillates. That is, when the same tension control method as in cold rolling is adopted in hot rolling, it is possible to improve strip thickness accuracy and strip shape by improving tension control responsiveness.However, tension control by roll reduction operation is performed in hot tandem. When individually adopted in the rolling mill group, the tension of the adjacent stand changes due to the required reduction operation of the tension correction stand. This causes a disturbance in the adjacent stands and causes a rolling-down correction operation, so that the rolling-down operation is alternately repeated in both stands, and at worst, the resonance occurs and the tension is in a diverging state. Therefore, the tension control method similar to that of cold rolling cannot be directly adopted for hot rolling.

An object of the present invention is to effectively prevent changes in tension between stands in hot tandem rolling and to perform stable tension control.

[0009]

A tension control device for a stand of a hot tandem rolling mill of the present invention is a hydraulic pressure determining a roll opening degree from an upstream side to a downstream side in a moving direction of a material to be rolled (1). Multiple stands (# 1 to # 7) with a rolling position controller (APC)
Of the tandem rolling mill sequentially arranged with each other, the tension detecting means (T) for detecting the tension of the material to be rolled (1) between the stands; an arbitrary i-stand every other stand and i + 1 of the next stage of the stand. First, the roll opening degree (Si + 1) of the i + 1 stand is controlled via the hydraulic pressure reduction position control device (APC) so that the tension of the rolled material (1) between the stands reaches the first target value.
Tension control means (ATC); looper (L) for pressing the rolled material (1) between the i + 1 stand and the i + 2 stand subsequent to the stand; and the rolled material (1) between the i + 1 stand and the i + 2 stand While controlling the pressing amount of the looper (L) so that the tension of the looper becomes the second target value, and further controlling the pressing amount of the looper (L) so that the pressing point of the looper (L) becomes the target height. And a second tension control means (LC) for controlling the roll peripheral speed (Vi + 1) of the i + 2 stand so that the tension of the material to be rolled (1) between the i + 1 stand and the i + 2 stand becomes the second target value. Equipped with. The elements in parentheses are corresponding elements of the embodiment described later.

[0010]

When the fluctuation of the tension of the material to be rolled occurs between the i stand and the i + 1 stand, the roll reduction amount Si + 1 of the i + 1 stand is corrected by the restraining operation of the first tension control means. The tension of the material to be rolled at is kept constant. However, this suppressing operation induces a tension disturbance of the rolled material between the adjacent i + 1 and i + 2 stands. For this tension disturbance,
Since the height of the looper installed between the i + 1 stand and the i + 2 stand changes and the loop amount changes immediately, the tension disturbance is absorbed as a mass flow change. At that looper height, the tension disturbance is corrected by the torque generated by the looper motor current output from the looper tension control system. After that, the second tension control means changes the roll peripheral speed Vi + 1 so as to return the height of the looper to a predetermined position.
Even if the rolling operation is performed against the tension fluctuation, there is no influence on the downstream side of the stand. Therefore, mutual resonance of the tension system between the i stand and the i + 1 stand and between the i + 1 stand and the i + 2 stand can be prevented.

That is, in the present invention, the tension control by the rolling down operation and the tension control by the looper operation are alternately used for each stand of the tandem rolling mill, so that even if a tension disturbance is generated in the adjacent stand by the rolling down operation, the looper is operated. As a result, the steel plate loop amount changes and the tension disturbance is absorbed, so that the occurrence of resonance can be prevented. As a result, even in the hot tandem rolling mill, the tension control can be performed by the rolling operation with high tension control response, and the strip thickness accuracy and strip shape of the material to be rolled can be improved. Other objects and features of the present invention will become apparent from the following description of embodiments with reference to the drawings.

[0012]

FIG. 1 shows a schematic structure of an example of a hot tandem rolling mill using the tension control device of the present invention. In the figure, the material 1 to be rolled moves from left to right. I, i + 1, i + in the figure
2, 2 and i + 3 are work rolls of arbitrary i stand, i + 1 stand, i + 2 stand, and i + 3 stand, and each has a backup roll below it. Each work roll is equipped with a roll-down position setting device APC, and the roll opening (roll-down position) can be set.

A tensiometer T is provided between the stands to detect the tension between the stands of the material 1 to be rolled. Also,
i + 1 stand, i + 3 stand, ..., i + n (here, n is an odd number), that is, every other one of the stands, a reduction tension controller ATC is provided to perform tension control by roll reduction. This rolling tension controller AT
C is a rolling position adjuster APC according to the detection value of the tensiometer T.
Control the rolling position of. Furthermore, the rolling tension controller ATC
A looper control system is provided between a stand having a stand and a stand next to the stand. The looper control system includes a looper L that presses the rolled material 1 from below, a looper motor that drives the looper L, a looper angle meter LH that detects the angle (height) of the looper L, and a tensiometer T and a looper angle meter LH. The looper controller LC or the like controls the looper motor according to the detected value. Also, the looper controller LC is
Right behind the position where the looper L is installed (left side in the figure)
Controls the roll peripheral speed of the stand. The looper control system controls the angle (height) of the looper L by driving the looper motor so that the tension reaches a target value according to the detected value of the tensiometer T, and the angle (height) of the looper L is adjusted. The roll speed is controlled so that the tension becomes a predetermined value and the tension becomes a target value.

Next, the tension control of the present invention will be described. Assuming that the tension fluctuation of the rolled material 1 occurs between the i stand and the i + 1 stand, first, the rolling tension controller AT
C controls the roll reduction amount Si + 1 of the i + 1 stand according to the change in the value of the tensiometer T. The roll reduction amount Si + 1 is i
It is a value calculated so that the tension between the stand and the i + 1 stand becomes a target value, and the contents of the calculation are already known. I + of the rolled material 1 is controlled by controlling the roll reduction amount Si + 1
The entry speed in one stand is adjusted, and the tension of the rolled material between the i stand and the i + 1 stand is kept constant. At this time, the forward tension of the i + 1 stand (the tension of the material to be rolled between the i + 1 stand and the i + 2 stand) varies with the change of the roll reduction amount.

Here, the tension fluctuation will be specifically described. Focusing on the tensions Δσ6-5 and Δσ5-4 of the intermediate stands (for example, between 6-5 stands and between 5-4 stands), this change (differential) d / dt ・ Δσ6-5 and d / dt ・ Δσ5-4 Is described by the equation of state as follows.

[0016]

[Equation 1]

Similarly,

[0018]

[Equation 2]

However, in the above equations (1) and (2), fi: advanced rate gi: reverse rate ΔS
i: Roll opening Δσi- (i-1): Stand tension Vr
i: Roll peripheral speed M0: Mill constant Qi: Plasticity coefficient
P: Rolling load.

Now, the variation Δσ5-4 of σ5-4 is set to the target value Δσ5-4r.
If you change the reduction ΔS5 of 5 stands to correct it to ef,
From equation (1), the inter-stand tension Δσ6-5 also changes.
Although omitted, the inter-stand tension Δσ4-3 is also represented by the formulas (1) and (2), and since Δσ5-4 influences this formula, a change also occurs in Δσ4-3. It should be noted that this modified control law is possible with the PI operation similar to cold rolling. The process up to this point is the same as the case where the rolling tension control used in cold rolling is used in the conventional hot rolling apparatus.

In the present invention, the looper L is arranged between the i + 1 stand and the i + 2 stand (immediately downstream of the stand for performing the rolling-down operation). The height of the looper L changes with respect to the forward tension fluctuation, and the loop amount immediately changes to absorb the tension disturbance as a mass flow change. That is,
The looper L acts as a buffer against tension fluctuation, and fluctuation in front tension is prevented. After that, the roll peripheral speed Vi + 1 is changed by the looper controller LC, and the height of the looper L returns to a predetermined position.

Now, the looper control system will be described more specifically. FIG. 2 is a block diagram showing the configuration of the looper control system more specifically. Considering the static balance between the looper driving torque GM and the torque G applied to the looper from the strip in the looper state as shown in FIG. The torque G from the strip is divided into the following three. 1) Torque due to tension T GT (T, θ) = k1 {sin (θ + θ2) -sin (θ-θ1)} T 2) Torque due to strip weight Ws and looper own weight WL GW (θ) = (k2 ・ Ws + k3 ・ WL) ) Cos θ 3) Torque due to strip bending GB (θ) = k4 (Lsin θ−H) cos θ where H is the pass line height, and k1, k2, k3, k4 are the looper arm length L, the looper dimension such as the looper installation position, It is a constant determined by the thickness, width and Young's modulus of the strip.

Therefore, the torque applied from the strip to the looper is expressed by the following equation. G (T, θ) = GT (T, θ) + GW (θ) + GB (θ) At this time, using the set tension T * and the detected looper angle θ as the looper drive torque, GM (T *, θ) = GT (T *, θ) + GW (θ) + GB (θ) If the looper is stationary,
The tension is the set tension for any looper angle. That is, static balance compensation is realized. Taking the above-mentioned stand 6-5 as an example, when tension Δσ6-5 fluctuates due to the disturbance due to −ΔS5, the balance of GM = G collapses and the looper angle changes. However, the tension is controlled so that the tension becomes the set tension at the new looper angle after the change.

On the other hand, there are restrictions on the looper angle due to problems such as the passage of the plate. For this reason, the looper angle is detected and the rolling roll speed of the upstream or downstream stand is corrected, whereby the angle of the looper is controlled to be constant (looper height control). The looper acts in the same manner between the stands 4 and 3.

With the above operation, the tension between the looper installation stands can absorb the tension fluctuation without affecting the tension between the adjacent stands. I stand and i + 1
Even if the tension fluctuation of the rolled material 1 occurs between the stands and the tension is controlled by rolling down at the i + 1 stand, the influence on the front tension (the tension of the rolled material between the i + 1 stand and the i + 2 stand) is absorbed by the looper operation. Therefore, mutual tension system resonance does not occur between the i stand and the i + 1 stand and between the i + 1 stand and the i + 2 stand.

FIG. 3 shows the overall structure of the hot tandem rolling mill of the present invention, and FIG. 4 shows the rolling control function of the hot tandem rolling mill shown in FIG.

In FIG. 3, each of # 1 to # 7 is a stand, and each stand has a work roll, a backup roll, a work roll driving motor, a load cell, a pressure reducing position setter APC, and the like. A tensiometer is installed between each stand to detect the tension between the stands of the rolled material. In the figure, ATC is a tension controller between stands due to reduction, Xray AGC is an X-ray monitor plate thickness controller, GM A
GC is a plate thickness controller, GM is a plate thickness calculator, LC is a looper controller, ASR is a main motor speed controller, and MFC is an exit speed compensator (mass flow compensator). In addition,
The material 1 to be rolled moves from left to right in the figure.

Each of the stand # 2, the stand # 4, and the stand # 6 has a tension control system (APC, ATC).
Etc.), between stands # 2- # 3, stands # 4-
A looper control system (looper L, looper goniometer LH, looper controller LC, etc.) is provided between # 5 and between stands # 6 and # 7. That is, assuming that the i, i + 1, and i + 2 stands described in FIG. 1 are one set of tension control devices, the device shown in FIG.
3), (# 3, # 4, # 5), and (# 5, # 6, #
It is composed of three sets of tension control devices of 7). The tension control by the rolling operation is the same as the control conventionally used for cold rolling, and the tension control by the looper operation is the control described with reference to FIGS. 1 and 2.

FIG. 5 is a block diagram showing the calculation of the exit speed compensator (mass flow compensator) MFC shown in FIG.

As described above, in the present embodiment, by alternately using the tension control by the rolling operation and the tension control by the looper operation, the tension disturbance generated by the rolling operation is absorbed by the tension control by the looper operation. It is possible to control tension with high responsiveness even in hot rolling.

[0031]

According to the present invention, the tension disturbance between the stands can be surely blocked by the characteristics of the looper, so that the tension control system by the roll operation can be adopted even in the hot tandem rolling mill group. Therefore, stable and high-speed tension control is realized, and high plate thickness accuracy and shape improvement can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of part of a hot tandem rolling mill using a tension control device of the present invention.

FIG. 2 is a block diagram showing a configuration of a looper control system.

FIG. 3 is a block diagram showing an overall configuration outline of a hot tandem rolling mill using the tension control device of the present invention.

FIG. 4 is a block diagram showing a rolling control function of the hot tandem rolling mill shown in FIG.

5 is a block diagram showing a calculation of an exit speed compensator (mass flow compensator) MFC shown in FIG. 3. FIG.

FIG. 6 is a block diagram showing an example of a conventional hot tandem rolling mill.

[Fig. 7] Conventional tension fluctuation reduction position (roll opening)
It is a block diagram which shows an example of the cold rolling tandem rolling mill suppressed by control.

8 is a block diagram showing a rolling control function of the rolling equipment shown in FIG. 7. FIG.

FIG. 9 is a block diagram showing the functional configuration of a rolling stand when the strip thickness is determined by the roll peripheral speed ratio between the stands, the strip thickness is controlled by the roll peripheral speed ratio control, and the inter-stand tension is controlled by rolling down. It is a figure.

[Explanation of symbols]

1: Rolled material (rolled material) # 1 to # 7: Rolling stand (stand) T: Tension meter (tension detecting means) APC: Reduction position setting device (hydraulic reduction position control device) ATC: Reduction tension controller ( First tension control means) L: Looper (looper) LH: Looper angle (height) meter LH: Looper control device (second tension control means)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Masaharu Moritani 1 Kimitsu, Kimitsu City Nippon Steel Corporation Kimitsu Steel Works (72) Inventor Hideo Katori 20-1 Shintomi, Futtsu City Shinnippon Steel Co., Ltd. Central Research Division (72) Inventor Takatsugu Ueyama 20-1 Shintomi, Futtsu City Nippon Steel Co., Ltd. Central Research Division (1) Ino Nobuo Fukui Kimitsu 1 Kimitsu, Japan Kimitsu Co., Ltd.

Claims (1)

Claim: What is claimed is: 1. A tandem rolling machine in which a plurality of stands having a hydraulic pressure reduction position control device that determines a roll opening is sequentially arranged from upstream to downstream in the moving direction of a material to be rolled. Tension detecting means for detecting the tension of the material to be rolled between the stands of the machine; the tension of the material to be rolled between any one of the i stands at every other stand and the i + 1 stand at the next stage of the stand is the first target value. So as to control the roll opening of the i + 1 stand via the hydraulic pressure reduction position control device; i + 1 stand and i + of the next stage of the stand.
A looper that presses the material to be rolled between the two stands; and a pressing amount of the looper is controlled so that the tension of the material to be rolled between the i + 1 stand and the i + 2 stand has a second target value. While controlling the pressing amount of the looper so that the target height is achieved, the i + 1 stand and i
A tension control device between stands of a hot tandem rolling mill, comprising: a second tension control means for controlling the roll peripheral speed of the i + 2 stand so that the tension of the rolled material between the +2 stands reaches a second target value.