JP2959698B2 - Finish rolling method of joining material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to hot finish rolling of a steel sheet, and more particularly to a method of finish rolling a joint of steel sheets.

[0002]

2. Description of the Related Art Conventionally, in a hot finishing mill, there is a rolling method in which a sheet bar is joined on a finishing entrance side. In this finishing mill, a looper is installed to control the tension between stands.

There are several methods for controlling the looper. Typical examples include a "conventional control method" and a "tension meter method" as described below.

First, in the "conventional control system", a constant or a torque corresponding to the looper angle is added to the looper shaft, and the main engine speed is changed according to the deviation of the actual value of the looper angle from the target value. FIG. 1 shows a block diagram of the control system.

In FIG. 1, the rolling rolls of the i-th stand and the i + 1-th stand use an electric motor as a speed control system, and S _{i, REF} and S _{i + 1, REF} are i-stand and i +, respectively.
This is the speed reference for one stand. T _REF is a strip tension reference, and the strip tension is controlled by detecting the strip tension T by the current of the looper motor. Θ _REF is a looper angle reference, and the output of the looper angle control is set to i so that the difference between this and the looper angle detection value θ becomes zero.
The looper speed is controlled by applying the voltage to the rolling roll drive motor speed control system of the stand.

Next, the "tension meter system" is a method of controlling the main machine speed so that the looper angle is controlled to be constant, the plate tension is obtained from a tension meter installed on the looper, and the plate tension is made to coincide with a target. FIG. 2 shows the configuration of the control system.

In FIG. 2, TM is a tension meter. The strip tension acts to depress the looper. The looper pressing force measured from the Re axis screws looper rotary shaft by the tension meter (TM), it will be controlled.

This tension meter system has the advantage that the looper is excellent in the angular tension stability, so that disturbance to other controls is small.

[0009]

However, when the joint is rolled by the above-described tension meter method, there are the following problems.

That is, the junction is locally extremely hot, and there is a further local low-temperature portion in the periphery, depending on the joining method. Rolling the joint causes portions having such local temperature fluctuation to pass through the rolling mill one after another. The fluctuation at this time is AGC (Autom
atic gauge control), causing large fluctuations in mass flow during rolling. Therefore, when the control is performed by the tension meter method, the fluctuation of the mass flow causes an extremely large fluctuation of the tension, which causes a serious problem in the thickness accuracy of the joint portion or the threading itself.

On the other hand, if the "conventional control system" is used over the entire length, there is a problem in the stability of the looper due to the presence of the joint, and interference with other controls is caused. There is a problem of adverse effects.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems, and an object of the present invention is to provide a method for finish-rolling a joint material which prevents breakage at a joint portion and enables stable threading. And

[0013]

SUMMARY OF THE INVENTION The present invention relates to a method for rolling a joint portion of a material to be rolled joined in front of a hot finish rolling mill for a steel sheet,
Before the joint enters the finishing mill ,
The above-mentioned object is achieved by raising the looper angle with respect to the angle, and rolling the joint portion back to the looper angle at the steady portion after the completion of the rolling at the joint.

[0014]

[0015]

The present invention is further provided to prevent interference between the looper angle and the tension of the material to be rolled during the rolling of the joint when rolling the joint in a hot finishing mill having a non-interference control system. The above-mentioned object is similarly achieved by temporarily changing the gain of the control system and performing rolling.

[0017]

When the present inventors use the above-mentioned "conventional control system" for rolling of a portion having extremely large disturbance such as a joint, the looper angle greatly varies, but the tension itself is at a fatal level. The present invention focuses on the fact that it does not result in the following, and proposes a finish rolling method of a joining material that enables stable threading.

That is, according to the present invention, before the joined portion of the material to be rolled enters the finishing mill , the looper angle of the stationary portion is determined in advance.
And it was rolled by increasing the looper angle, and return to the looper angle again constant region After rolling the joint is completed so as to roll
Therefore, it is possible to prevent the joint from being broken, and to realize a stable threading.

[0019]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIG. 3 is a configuration diagram showing an outline of a finishing mill for performing finish rolling according to the present embodiment.

In the actual finish rolling, a rolling mill having 6 to 7 stands is usually used. However, in the present embodiment, a simplified description will be given with a rolling mill having 2 stands.

In FIG. 3, 1 is a material to be rolled, 2 is a joining device, 4 is a finishing mill, 6 is a joining control device, 8 is a tracking device, 10 is a pinch roll, 12 is a rotation sensor, 1
4 is a looper and 16 is a tension control device.

Hereinafter, the operation of the first embodiment will be described first.

The material to be rolled 1 is joined by a joining device 2 and subsequently rolled to a desired thickness by a finishing mill 4 installed. At this time, the rolling control of the steady portion other than the joining portion is performed by the tension meter method.

Information indicating that the material to be rolled 1 has been joined by the joining device 2 is transmitted from the control device 6 of the joining device 2 to the tracking device 8. The tracking device 8 for the material 1 to be rolled is provided with a rotation sensor (PLG or the like) 12 provided at the shaft end of the pinch roll 10 installed between the joining device 2 and the finishing mill 4 to detect the rotation of the pinch roll 10. Tracking of the junction is performed using the output.

Immediately before the joining point enters the finishing mill 4, the information is output to the tension controlling device 16 for controlling the tension through the finishing mill 4 and the looper 14. The tension control device 16 receives the signal and switches the tension control between the finishing mills 4 from the tension meter system to the “conventional control system” to raise the angle control target of the looper 14. The joint is a rolling mill 4
When passing through the inside, the temperature fluctuation causes a large mass flow fluctuation, and the looper angle fluctuates greatly, but the tension disturbance is not large.

Further, the tracking device 8 continues to monitor the progress of the material to be rolled even after the material to be rolled has entered the rolling mill 4, and the sheet thickness rolling schedule and the sheet feed length of the pinch roll 10 on the finishing side. When it is detected that the joining point has passed through the rolling mill 4, the tension control device 16
To output this signal. The tension control device 8 switches the control of the looper 14 again to the tension meter system based on this signal.

The tension in the joint rolling method described above,
FIG. 4 shows the relationship between the angle and the time.

FIG. 4A shows a state before passing through the joining portion, as shown in FIG. 5, and before that, the stationary portion. Since the tension control of the tension meter system is performed, the movement of the looper 14 is stabilized.

When the tracking device 8 detects the approach of the joint, the control of the looper 14 is switched to the "conventional control system", and the looper angle is further increased. As a result, even when a mass flow fluctuation occurs, it is possible to absorb the tension at the looper angle, reduce the disturbance of the tension, and cope with the loop amount fluctuation accompanying the tension. This shows a state during passage through the junction of FIG. 4B, and FIG. 6 shows a conceptual diagram thereof.

FIG. 4C shows a state after passing through the joining portion as shown in FIG. 7. After that, the tension meter system is controlled again.

In the first embodiment, when rolling the joint,
Although the control is switched to the conventional control, the embodiment of the present invention is not limited to this example.

Next, a comparative example will be described.

In this comparative example, first, the joint shape of the material to be rolled is determined by the joint shape recognition sensor 18 shown in FIG. As a result, when the joining shape is incomplete as shown in FIG. 8, the speed ratio between the two rolling mills 4 is stored immediately before the joining point enters the rolling mill 4, and the speed ratio is maintained thereafter. The lower part of the looper 14 is lowered, and the joining portion is rolled by looperless control.

After passing through the joint, raise the looper 14 again,
The tension control by the looper 14 is started again after a certain period of time has passed after the contact with the plate or the raising of the looper 14.

Next, a second embodiment of the present invention will be described.
You. The second embodiment relates to a tension control system having a non-interference control system for controlling the tension and the looper height with both the looper torque and the rolling mill speed.

The looper non-interference control makes the looper angle and the tension incoherent to realize the stability of the control and the improvement of the response, and aims at the improvement of the tension control accuracy by the actual tension feedback control using the measured tension value. It is a thing.

FIG. 9 shows the configuration of non-interference control. In FIG. 9, the control device is a main controller (LTC, LH
C) and the cross controller 20.
The cross controller 20 is a pre-compensation element for eliminating mutual interference between the tension and the looper angle. The looper tension controller (LTC) and the looper height controller (LHC) each perform a proportional-integral operation to output a main engine rotation speed correction amount and a looper motor rotation speed correction amount. 24 is controlled.

In the second embodiment, the gain of the control system provided to prevent mutual interference is temporarily reduced during the passage through the junction, so that the gain of the control system can be reduced with respect to the steady portion in the state where the gain is increased. In addition, the joints are similar to conventional controls. Thus, there is an advantage that no disturbance of tension is applied to the joint passing plate, there is no need to switch the control system, and there is no need to hold two types of control systems.

[0040]

As described above, according to the present invention,
The joining portion can be passed through a finish rolling mill without a large change in tension, and the effect of improving the accuracy of the thickness and width of the joining portion can be obtained.

Further, it is possible to reduce an accident that the joint is broken in the rolling mill, maintain the tension control accuracy of the steady portion well, and have the effect of not impairing the dimensional control accuracy of the steady portion.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an outline of a conventional control system.

FIG. 2 is a configuration diagram showing an outline of a conventional tension meter type control system.

FIG. 3 is a block diagram showing an outline of a control system to which the method of the present invention is applied.

FIG. 4 is a diagram showing a state of control according to the first embodiment of the present invention.

FIG. 5 is an explanatory view showing a state before a joining portion passes through a rolling mill.

FIG. 6 is an explanatory view showing a state in which a joint is passing through a rolling mill.

FIG. 7 is an explanatory view showing a state after a joining portion has passed through a rolling mill.

FIG. 8 is a plan view showing a state in which a joint shape of a joint portion is incomplete.

FIG. 9 is a block diagram showing an outline of a non-interference control system.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Material to be rolled 2 ... Joining device 4 ... Finishing rolling machine 6 ... Joining control device 8 ... Tracking device 10 ... Pinch roll 12 ... Rotation sensor 14 ... Looper 16 ... Tension control device 18 ... Joining shape recognition sensor

Continuation of the front page (56) References JP-A-5-237529 (JP, A) JP-A-6-15317 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B21B 37 / 50 B21B 1/26

Claims (2)

(57) [Claims] When rolling a joined portion of a material to be rolled joined in front of a hot finish rolling mill for a steel sheet, a looper of a stationary portion is required before the joined portion enters the finishing mill.
A finish rolling method for a joining material, characterized in that the looper angle is increased with respect to the angle, and after the joining portion rolling is completed, the looper angle is returned to the steady portion again. 2. A control system provided to prevent interference between a looper angle and a tension of a material to be rolled during rolling of a joint when rolling a joint material in a hot finishing rolling mill having a non-interference control system. A finishing material rolling method, wherein the rolling is performed while temporarily changing the gain.