JPS6127124B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a looper control method for a rolling mill that controls the inter-stand tension of a strip by controlling a looper disposed between the stands, and particularly relates to a method for controlling a looper in a hot strip finishing rolling mill. The present invention relates to a modification of a looper control method when the looper starts up, which is suitable for application to an inter-stand looper disposed between stands.

Conventionally, the looper between the stands of a hot stand mill was not equipped with a tension detector to detect the actual tension of the strip, but in recent years, it has been possible to A tension detector that can be used has been developed, improving the accuracy of tension control between strip stands, and making a major contribution to improving dimensional accuracy of plate thickness, plate width, etc. However, in the past, when the looper rose and the looper collided with the strip after the tip of the strip got caught in the next stand during sheet threading, it was unavoidable that a large tension fluctuation occurred. Significant dimensional variations occurred at the leading edge of the strip.

That is, for example, in a hot strip mill finishing mill having an i-th stand 11 and an i+1-th stand 13 each having work rolls 10 and 12 as shown in FIG. 1, the strip 14 is It is rolled while applying tension by a looper 16 disposed between the i-th stand 11 and the i+1-th stand 13. The looper 16 is driven by a looper drive motor 18, and the strip 1 is driven by the torque generated by the looper drive motor 18.
4 has tension added to it. Also, the i-th stand 1
1 work roll 10 has a rolling mill drive motor 20
is driven by. In such a finishing mill, when passing the strip, the tip of the strip 14 is at the i-th point.
When the work roll 10 of the stand 11 is rolled and bit the work roll 12 of the i+1st stand 13, a rolling load signal is generated in the load cell 22 disposed in the i+1st stand 13, and the mill biting signal generator 24 generates a rolling load signal. A signal is applied to the looper drive motor control device 26, and a torque command is output from the looper drive motor control device 26 to the looper drive motor 18 via the torque control circuit 28, and the looper 16 starts up. Collisions with strip 14.

On the other hand, during steady rolling, the looper drive motor control device 26 controls the torque of the looper drive motor 18 via the torque control circuit 28 based on the signal from the tension detector 30 installed in the looper 16. The rolling mill drive motor control device 34 controls the rotational speed of the rolling mill drive motor 20 based on the strip tension control so that the tension between the stands 14 becomes a predetermined value and the signal from the looper angle detector 32. At the same time, the looper height control is carried out so that the tension becomes a predetermined value, the tension between the stands of the strip 14 is made constant, and the looper angle is made constant, thereby improving dimensional accuracy and rolling workability. It's on.

However, in the past, the timing from starting up the looper during sheet threading to entering control during steady rolling was given by a timer setting, etc. after the tip of the strip 14 was bitten by the work roll 12 of the i+1th stand 13. looper 16 and strip 1
4 collided, it was inevitable that a large tension fluctuation would occur.

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and is a looper control for a rolling mill that can reduce tension fluctuations between stands during strip passing and improve strip dimensional accuracy. The purpose is to provide a method.

The present invention provides a looper control method for a rolling mill in which the inter-stand tension of a strip is controlled by controlling a looper disposed between the stands. At the end of the looper angle, where the looper angle starts height control, the looper is started up by looper angular velocity control, which controls the speed of the looper drive device so that the angular velocity of the looper rise becomes a predetermined value, and the looper angle starts height control. When the looper angle reaches or exceeds the starting looper angle, in addition to the looper angular velocity control, looper height control is performed to control the speed of the rolling mill drive device so that the looper angle becomes a predetermined value, thereby achieving the above purpose. This is what I did.

Also, check whether there is a collision between the looper and the strip.
Collision between the looper and the strip is reliably detected by detecting the output of a tension detector disposed in the looper for detecting the actual tension of the strip.

The principle of the present invention will be explained below. The inventors have developed a strip with a rolled size of 3.2 mm x 1200 mm.
When the tension generated when the looper and the strip collided with the sixth looper was investigated, it was experimentally confirmed that as the angular velocity of the looper at the time of collision increases, the generated tension increases as shown in FIG. 2. Therefore, if the looper is made to collide with the strip by reducing the angular velocity of the looper, the generated tension will also be reduced and tension fluctuations can be reduced. However, if the looper angular velocity when starting up the looper is slow, the length to be rolled without tension becomes long, making the rolling operation unstable.
Additionally, in the current looper startup, the looper is launched with almost constant torque, so if the collision angle between the looper and the strip becomes large, the looper angular velocity increases in proportion to the required time, so the This will create a lot of tension in the strip. Therefore, as a result of investigating the time from the start of the rise of the looper to the collision between the strip and the looper, we found that, for example,
It was found that it is sufficient to collide the strip and the looper at an angular velocity of about 0.4 rad/sec. That is, when the looper rises, if the looper is raised at a constant angular velocity of about 0.4 rad/sec, the tension generated between the stands will not be too large, and the time from the rise of the looper to the collision with the strip will be reduced. It's not long either,
It does not impair the stability of rolling work. In this way, it has been found that good results can be obtained by causing the strip and the looper to collide with each other by controlling the angular velocity of the looper so that the angular velocity of the rise of the looper becomes a predetermined value when the looper rises.

Next, considering the timing of transition from looper start-up control to steady rolling control, it is sufficient to perform angular velocity control as described above when the looper starts up, but this control can also be applied after the looper and strip collide. If we continue, the looper will push up the strip at the commanded angular velocity,
Significant tension is generated, eventually leading to strip rupture. Therefore, when the looper and the strip collide, the angular velocity control is terminated and a transition is made to the known steady rolling control that uses both the strip tension control and the looper height control. At this time, in order to reliably detect the collision between the looper and the strip, it is preferable to detect the presence or absence of a collision between the looper and the strip according to the output of a tension detector for detecting the actual tension of the strip.

If the angle at which the looper and the strip collide is high, as described above, angular velocity control is performed until the looper and strip collide, and after the looper and strip collide, strip tension control and looper height control are performed together. However, in this case, when the looper angle reaches a predetermined height control start angle θ ^* , the looper angle is changed from start-up angular velocity control to a predetermined value. By shifting to looper height control, the rolling time without strip tension can be shortened.
The stability of rolling work can be improved.

The process from looper startup to transition to looper control in steady rolling as described above is shown in a flowchart as shown in FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a looper control device for a rolling mill employing a looper control method according to the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 4, this embodiment has work rolls 10, 12, a looper 16,
looper drive motor 18, rolling mill drive motor 20,
load cell 22, mill bite signal generator 24,
Looper drive motor control device 26, torque control circuit 28, tension detector 30, looper angle detector 32,
In a rolling mill looper control device having a rolling mill drive motor control device 34, the looper drive motor 1 is controlled according to the output of the looper drive motor control device 26.
8 is provided with a speed control circuit 36 that outputs a speed command, and when the looper starts up, the looper 16 is started up by looper angular velocity control so that the angular velocity of the rise of the looper becomes a predetermined value, and before the looper 16 collides with the strip 14. When the looper angle reaches a predetermined height control start angle θ ^* , looper height control is started so that the looper angle becomes a predetermined value, and it is determined that the looper 16 collides with the strip 14. After the tension is detected by the output of the tension detector 30, the strip tension control is performed so that the inter-stand tension of the strip 14 becomes a predetermined value according to the tension detection value, and the looper height control is performed simultaneously. This is what I did.

As the tension detector 30, a known device such as a load cell that directly detects the force, or a device that uses a torsion bar and detects the torsion angle of the bar, etc. can be used. In the case of using a load cell, for example, as shown in FIG. 5, a load cell 30A as the tension detector 30 is inserted under a bearing 16C that rotatably supports the looper roll 16A at the tip of the looper arm 16B. 16D is a mounting bolt for the bearing 16C.

Detection of tension by the tension detector 30 having such a configuration is performed as follows. Now, as shown in Fig. 6, the load F applied to the road sail 30A is
Assume that the strip 14 acts at an angle of θ ₁ with respect to the vertical direction, and the angles of the strip 14 with respect to the horizontal direction are θ ₂ and θ ₃ , respectively. In addition, each angle θ
₁ , θ ₂ , and θ ₃ can be known from the rotation angle (height) of the looper 16, and the load F is the sum of the bearing loads on both sides of the looper roll 16A.

In this case, the actual tension T acting on the strip 14
can be determined by the following equation from the following equation: P=T(sin θ ₂ +sin θ ₃ )+α F=P cos _{θ 1} .

T={(F/cos θ ₁ )−α} /(sin θ ₂ +sin θ ₃ ) Here, α is a correction term that takes into consideration the weight of the strip 14 and the like.

The action will be explained below. When the tip of the strip 14 first bites into the work roll 10 of the i-th stand 11 and then into the work roll 12 of the i+1-th stand 13, a rolling load signal is generated in the load cell 22, and the mill bite signal generator 24
A strip biting signal is generated. In response to this strip biting signal, the looper drive motor control device 26 outputs a speed command to the looper drive motor 18 via the speed control circuit 36, causing the looper to move at a predetermined angular velocity, for example, 0.4 rad/sec. raise. When the looper 16 starts to rise and collides with the strip 14, which is detected by the output of the tension detector 30, the looper drive motor controller 26
stops the looper angular velocity control that controls the speed of the looper drive motor 18, and controls the looper drive motor 18 so that the tension between the stands of the strip 14 becomes a predetermined value according to the tension detection value output from the tension detector 30.
The known strip tension control for controlling the torque, etc. of the strip is started. On the other hand, when the looper rises, the angle of the looper is detected by the looper angle detector 32, and if the looper angle is equal to or greater than a predetermined height control start angle θ ^* , or if the tension is caused by the collision between the strip 14 and the looper 16 A rotation speed command is output from the rolling mill drive motor control device 34 to the rolling mill drive motor 20 in accordance with the output of the looper angle detector 32 at the earlier timing of detection by the output of the detector 30, Looper height control is started to control the speed of the rolling mill drive motor 20 so that the looper angle becomes a predetermined value.

In the above embodiment, the present invention is applied to the control of the inter-stand looper of a finishing rolling mill of a hot strip mill, but the scope of application of the present invention is not limited to this, and is applicable to long steel such as wire rods. It is clear that the present invention can be similarly applied to control of loopers between stands of a rolling mill.

As explained above, according to the present invention, it is possible to greatly suppress the large tension generated when the looper collides with the strip, which could not be avoided with the conventional looper control method, and the tension between the stands during sheet threading can be reduced. This has the excellent effect of reducing fluctuations and improving the dimensional accuracy of the strip.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of an example of a looper control device for a rolling mill in which a conventional looper control method is adopted, and Fig. 2 shows the looper angular velocity at the time of collision to explain the principle of the present invention. FIG. 3 is a flowchart showing the looper control method for a rolling mill according to the present invention, and FIG. 4 is a diagram showing the looper control method for a rolling mill in which the looper control method according to the present invention is adopted. Block diagram showing the configuration of the embodiment of the device, No. 5
The figure is a side view of the tip of the looper, showing a known tension detector used in the above embodiment, and FIG.
FIG. 2 is a diagram for explaining a known tension detection method using the tension detector. 10, 12... Work roll, 14... Strip, 16... Looper, 18... Looper drive motor, 20... Rolling mill drive motor, 22... Load cell, 24... Mill bite signal generator, 26...
... Looper drive motor control device, 28 ... Torque control circuit, 30 ... Tension detector, 32 ... Looper angle detector, 34 ... Rolling mill drive motor control device,
36...Speed control circuit.

Claims (1)

[Claims] 1. In a looper control method for a rolling mill in which the tension between the stands of the strip is controlled by controlling the looper disposed between the stands, there is a problem in which the strip collides with the looper when the looper is started up. Previously, at the end of the looper angle where the looper angle starts height control, the looper is started up by looper angular velocity control that controls the speed of the looper drive device so that the angular velocity of the looper rise becomes a predetermined value.
When the looper angle exceeds the looper angle at which height control is started, in addition to the looper angular speed control, looper height control is performed to control the speed of the rolling mill drive device so that the looper angle becomes a predetermined value. Features a rolling mill looper control method. 2. The rolling mill according to claim 1, wherein the presence or absence of a collision between the looper and the strip is detected by the output of a tension detector disposed on the looper for detecting the actual tension of the strip. Looper control method.