JPH0416244B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for preventing rolling accidents due to flaws in steel strip in continuous cold tandem rolling equipment.

[Conventional technology]

In cold tandem rolling equipment, conventionally, the distance between the uncoiler and the #1 stand is short and no flaw detector is provided. Therefore, flaws existing in the steel strip, most typically pitting flaws, cannot be discovered before the steel strip enters the #1 stand, and the portion is simply inserted into the rolling mill and rolled. Parts with open flaws may break in the tandem rolling mill. As a result, rolling operations were forced to stop for long periods of time in order to deal with damage to the rolling rolls and broken plates that remained inside the rolling mill, resulting in significant losses due to roll replacement and reduced work efficiency.

Furthermore, even if a flaw detector is installed in front of the rolling mill, if it is not placed sufficiently far from the rolling mill, the speed of the detected flaw will be reduced before it enters the #1 stand, and it will not be possible to stop it in front of the stand. It is possible and
Conventional non-continuous cold rolling mills cannot prevent the above-mentioned accidents.

Therefore, in the past, when holes and flaws were found in the steel strip during the pickling process in the previous process, by providing information on the approximate location, in the case of cold tandem rolling, low-speed rolling, visual inspection and monitoring at the entrance of the rolling mill. These efforts were conducted to discover flaws, and by doing so, measures were taken to prevent plate breakage, roll damage, etc. inside the rolling mill.

[Problem that the invention seeks to solve]

However, this imposes a heavy burden on operators and significantly reduces work efficiency.

An object of the present invention is to reduce the amount of work required to deal with pitting defects and the like.

[Means for solving problems]

The feature of the method of the present invention for achieving the above object is that in continuous cold random rolling equipment that performs tracking by detecting holes drilled at processing change points of the steel strip, holes are drilled at predetermined positions in front of the tandem rolling mill. A detector is provided, and based on the detection signal of the hole detector, the measured length of the hole interval is compared with a pre-given process change point length, and if the measured length is outside the allowable range of process change point length. In this case, the hole is determined to be a hole and the steel strip is decelerated or stopped.

Until now, flaws had not been detected in front of the #1 stand of the rolling mill even in equipment that has pickling equipment and cold tandem rolling equipment in series, but based on the present invention, for example, continuous annealing equipment, plating equipment, etc. In the process line, a tracking device (for example, Japanese Patent Publication No. 61-21905) that tracks holes that indicate the welding positions where steel strips are connected is used to calculate whether the hole is for tracking or a perforation flaw. In the case of open cracks, etc., the tandem rolling equipment is decelerated or stopped to prevent rolling troubles such as roll breakage and plate breakage.

[Action of the invention]

Hereinafter, the method of the present invention will be explained in detail with reference to Examples. Figure 1 shows an example in which the present invention is applied to pickling and cold tandem rolling mill equipment;
2 is a control computer, 3 is a speed control device, 4 is a pilot generator (PG) that measures the rotational speed of the electric motor 7 of the bridle roll 8, 5 is a pulse generator (PLG) that measures the amount of movement of the passing steel strip S; 6 is a hole detector consisting of a projector and a light receiver that detects holes in the steel strip; 7 is a motor for the bridle roll 8; is the electric motor of the rolling mill 10. The rolling mill 10 is a tandem rolling mill,
10' is a #1 stand, 11 is a winding machine (carousel reel), and 12 is an electric motor of the winding machine.

The effects based on the above configuration will be described. first,
The steel strip S to be rolled is connected by a welding machine (not shown) on the entry side of the pickling tank to the preceding steel strip and the following steel strip, and at the same time, the processing changes, that is, the changes in the manufacturing instructions and the steel At the point where the specifications of the strip change (welding point), a hole (for example, 15 m/m in diameter) of a size that does not interfere with rolling work is drilled in the center of the strip in the width direction.

The hole interval length of this steel strip S is generally 100~
Although it is approximately 1500 m, this length information is input into the host computer 1 in advance and is output to the control computer 2. The amount of movement of the passing steel strip S is constantly measured by the PLG 5 and input to the control computer 2. When the hole detector 6 detects a hole, the detection signal is input to the control computer 2, and the computer 2
Compare the steel strip length information given in advance and the measured hole interval length, and if the difference is outside the tolerance value (±10m), it is determined that it is not a hole that has been changed, but a hole opening flaw. In order to immediately decelerate the steel strip S or stop it before it is caught in the #1 stand, the deceleration rate is calculated using the following formula.

u=V ² /2l...(1) where, u: deceleration rate, V: speed of electric motor 7, l: distance between #1 stand 10' and hole detector 6. The calculator 2 is attached to the electric motor 7 that drives the bridle roll 8 when a hole (flaw) is detected.
The speed V is read at PG4, and the deceleration rate u is calculated based on l set in the calculator 2 in advance. The calculation results are output to the rolling mill speed control device 3, and the speed control device 3 controls each electric motor 7, 9, 12.
Decrease the speed of the vehicle by the specified deceleration rate.

If the comparison result is within the allowable value, it is determined that the hole is a tracking hole, and the calculation of the deceleration rate, etc. described above is not performed, and the rolling mill speed control device 3 is not instructed to decelerate, so the predetermined speed is rolling continues.

A plurality of hole detectors 6 are arranged in the width direction to cover detection in the width direction of the steel strip S. The installation position is determined taking into account the maximum speed and maximum deceleration rate of the cold tandem rolling mill 10, but in this embodiment, the cold tandem rolling mill 10 is decelerated so as to stop in front of the #1 stand 10'. Taking into consideration the maximum speed of the rolling mill 10 of 400 mpm, the maximum deceleration rate of 44 mpm/s, detection errors, equipment layout, etc., the detector 6 was installed with l being 62 m.

In addition, since the hole detector 6 cannot judge how much trouble the flaw will cause, the operator should stop the part with the flaw in front of the #1 stand, and then judge the state of the flaw. If there is a possibility of breakage, increase the distance between the rolls and decide whether to pass the material at low speed without rolling it or to roll it at reduced speed to prevent accidents. When it is known in advance that the steel strip is thick and the rolling reduction is low, and there is little possibility of breakage even after rolling, the operator may decide to increase the threading speed (30 to 30 mm) without stopping.
50mpm) through the rolling mill.

In addition, the allowable value of the measurement length of the steel strip S is ±10 m from the allowable passing length necessary for measurement accuracy and accident prevention.
However, the value can be determined based on the performance of each equipment and measuring instrument.

〔Example〕

A hole detector 6 is installed at a position 62 m (l) in front of the #1 stand 10' of the continuous cold tandem rolling mill 10 shown in Fig. 1, and the steel strip is 0.4 mm thick and has a width of 910 to 920 mm.
Steel strip S made by connecting plates of different widths (a tracking hole is drilled near the welding point, which is the change point)
Continuously, the steel strip speed on the entry side of #1 stand 10'
Rolled at 300mpm. Since a hole was detected outside the allowable range of the change point, I immediately decelerated at a deceleration rate of 15mpm/s and stopped the flaw detection part in front of #1 stand 10'.
Upon inspection, we found a hole with a diameter of approximately 5 mm. If rolled at the planned rolling reduction rate, it is determined that the plate will break, so rolling accidents can be prevented by widening the gap between the rolls and allowing the sheet to pass through the flawed area at approximately 50mpm through the rolling mill without rolling. did.

〔Effect of the invention〕

As explained above, according to the method of the present invention, holes in the steel strip are detected at the entrance side of the rolling mill, and by decelerating or stopping the rolling mill, troubles such as plate breakage and roll breakage can be prevented. Compared to decelerating work in advance by informing the flaw location from the process, this method has superior effects such as improving work efficiency, reducing the operator's workload, and stabilizing operations.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of an apparatus for carrying out one embodiment of the present invention. 1: Host computer, 2: Control computer, 3: Speed control device, 4: Pilot generator, 5: Pulse generator, 6: Hole detector, 7: Electric motor,
8: Bridle roll, 9: Electric motor, 10: Cold tandem rolling mill, 10': #1 stand, 11:
Winder, 12: Electric motor, S: Steel strip.

Claims (1)

[Scope of Claims] 1. A method for preventing rolling troubles in continuous cold tandem rolling equipment in which holes drilled at processing change points of a steel strip are detected and tracked, comprising: providing a hole detector in front of the tandem rolling mill; When the hole drilled at the processing change point of the band passes through the hole detector, the measured length of the hole interval is calculated based on the detection signal of the hole detector, and the measured length of the hole interval is calculated from the previously given length. A method for preventing rolling troubles in continuous cold tandem rolling equipment, which comprises comparing the hole interval length and decelerating or stopping the steel strip when the difference exceeds a predetermined tolerance.