JPS6352964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plate thickness control device for a cold rolling mill, and particularly to a plate thickness control device that uses both BISRA AGC and reduction monitor AGC.

BISRA is used for plate thickness control in cold rolling mills.
AGC and reduction monitor AGC are used together to improve plate thickness accuracy. FIG. 1 shows an example of a conventional plate thickness control device using such an AGC.

In FIG. 1, the cold rolling mill includes a first stand 3 and a second stand 4 for rolling the steel plate 2 discharged from the payoff reel 1, as well as a plurality of stands. is composed of work rolls 5a and 5b that directly roll the steel plate 2, back-up rolls 6a and 6b that back up the work rolls 5a and 5b, and a hydraulic cylinder 7 that applies a rolling force to the back-up rolls 6b. ing. Rolling control is performed by driving the hydraulic cylinder 7 based on the BISRA AGC and the rolling reduction monitor AGC.

BISRA AGC detects the rolling pressure detected by the load cell (rolling pressure gauge) 8 installed on the back-up roll 6a as a change in the thickness and hardness of the base plate, and the change is proportional to the amount of change in this detection signal. This is done by the BISRA AGC circuit 9 which performs plate thickness control while correcting the hydraulic cylinder 7 by ΔS, thereby reducing the range of plate thickness variation on the exit side of the first stand 3.

On the other hand, the reduction monitor AGC controls the hydraulic cylinder 7 to correct the plate thickness deviation amount detected by the X-ray thickness gauge 10 provided on the exit side of the first stand 3.
This is performed by the pressure reduction monitor AGC circuit 11 that controls the pressure reduction. The output signal of the reduction monitor AGC circuit 11 and the output signal of the BISRA AGC circuit 9 are added by an adder 12, and the hydraulic cylinder 7 is controlled by the added output.

By the way, in the conventional plate thickness control device, there are two systems.
Since the AGC is configured to constantly control the hydraulic cylinder via the adder 12, when controlling an excessively thick plate such as a welding point, as shown in Fig. 2,
BISRA AGC is activated to control the tightening operation when passing through during welding, but the welding point is
After passing through the stand 3, the reduction monitor AGC 9 using the X-ray thickness gauge 10 issues a tightening command, resulting in an excessively thin plate.

This is because the welding point is BISRA at the 1st stand 3.
Tightening control is performed by AGC and good plate thickness control is performed, but DDC (Direct Digital Control) that performs BISRA AGC
Over-thickness occurs at the initial stage of the weld due to the sampling time, the time required for calculation, and the delay in response time of the hydraulic reduction system such as piping. This initial thick part is the X on the exit side of the first stand 3.
When the wire thickness gauge 10 is reached, the reduction monitor AGC functions and a tightening signal is fed back to the first stand 3, but at this point the welded part is
Because the tightening command from the reduction monitor AGC is received when the plate is passing through the stand 3 and has a normal thickness, the plate becomes too thin.

As mentioned above, in the past, the reduction monitor AGC was performed after controlling the thickness of overthick areas such as welding points using BISRA AGC.
Due to the time delay caused by the AGC's PI (proportional/integral) operation and the distance between the exit side of the first stand and the X-ray thickness meter, there was an inconvenience in that the board thickness was controlled to be too thin.

An object of the present invention is to provide a cold rolling mill that maintains control of the reduction monitor AGC until the overthick part passes through the thickness detection position, in order to prevent the plate thickness from being controlled too thin. The present invention provides a plate thickness control device.

That is, the present invention monitors the output of the BISRA AGC, and determines whether the welded part has passed the first stand based on the fact that the BISRA AGC output has increased by a certain value or more during several sampling time periods, Based on this determination, the output of the reduction monitor AGC is held, and the hold is released at the timing when the weld passes the X-ray thickness gauge. The timing of passage of the X-ray thickness gauge is determined by providing data to the DDC, such as the preset length of the welded part, the reduction rate and advancement rate of the first stand, and the peripheral speed of the roll of the first stand. Can be done.

FIG. 3 shows an embodiment of the present invention,
Since the same reference numerals are used for the components shown in FIG. 1, _duplicate explanations will be omitted. In addition to the output signal, the roll peripheral speed of the first stand 3
V _R , advance rate F _l and reduction rate F _P of the first stand 3,
a control unit 30 that sends a control signal S _c to the reduction monitor AGC circuit 11 using each of the welding part length L _w , the distance d between the first stand and the thickness detector, and the welding point detection signal S _wd as input signals; The structure is different from that shown in FIG.

In the above configuration, first, the welding point is measured during several sampling time periods (for example, 150 msec for 5 samplings) of the pressure monitor AGC.
Judgment is made based on whether the output of BISRA AGC increases by 30μm or more in the tightening direction. If it is determined that the welding point has passed, a control command S _c for holding the roll-down monitor AGC output is output to the roll-down monitor AGC circuit 11, assuming that the welding point has passed. Based on the input information (S _o , V _R , F _l , F _P , L _w ), the control unit 30
Detect passage of the welding point, calculate the welding point passing time t _w to the installation position of the X-ray thickness gauge 10, and calculate this passing time.
When _tw is reached, the hold of the pressure reduction monitor AGC is released, and the pressure reduction monitor AGC circuit 11 is returned to its normal operating state.

The above process is shown in the flowchart in the fourth section.
It is a diagram. As mentioned above, by holding the reduction monitor AGC every time an overthick part is detected,
Even after passing through the welding point, a steel plate with good thickness accuracy without being too thin can be obtained.

As is clear from the above, according to the present invention, the output of the reduction monitor AGC is held until the welding point finishes passing between the stand and the installation position of the thickness gauge, so that the plate thickness is controlled to be too thin. It is possible to prevent this from happening.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing a conventional plate thickness control device, Fig. 2 is an explanatory diagram of control in the case of causing excessive thinning, Fig. 3 is a block diagram showing an embodiment of the present invention, and Fig. 4 is a block diagram showing a conventional plate thickness control device. 4 is a flowchart showing the processing according to the embodiment shown in FIG. 3; 1... Payoff reel, 2... Steel plate, 3... First stand, 5a, 5b... Work roll, 6
a, 6b...Backup roll, 7...Hydraulic cylinder, 8...Load cell, 9...BISRA
AGC circuit, 10... X-ray thickness gauge, 11... Rolldown monitor AGC circuit, 12... Adder, 20... Pulse generator, 30... Control section.

Claims (1)

[Claims] 1 A first AGC control system that performs plate thickness control based on the rolling pressure detection value of the stand, and a first AGC control system that detects the plate thickness on the outlet side of the stand with a thickness gauge and controls the plate thickness so that the deviation in the outlet side plate thickness falls within a predetermined range. In a plate thickness control device for a cold rolling mill that performs cold rolling with a second AGC control system that performs feedback control on the first AGC control system, when the first AGC control system continues to output a control output equal to or higher than a set value for a certain period of time. a control unit that holds the output of the second AGC control system and releases the output hold of the second AGC control system when it is determined that the welded part of the rolled material has passed the installation position of the thickness gauge; A plate thickness control device for a cold rolling mill, characterized in that it is provided with.