JP2021030240A - Cold tandem rolling equipment and cold tandem rolling method - Google Patents

Abstract

To provide cold tandem rolling equipment and a cold tandem rolling method in which plate rupture occurrence is predicted at a stage before the plate rupture occurrence in implementing cold tandem rolling on a coil with a large unevenness in deformation resistance distribution, like a self-annealing coil, and in which an emergency stop of the rolling can be made, in order to minimize degradation in productivity accompanying a plate rupture emergency stop.SOLUTION: In the cold tandem rolling equipment, a breakage part detector is disposed for detecting generation of broken parts not yet ruptured on a strip to be rolled, at least on an outlet side of a first rolling mill stand among multiple rolling mill stands, and an emergency stop device is provided for emergency stopping of the rolling based on a detection result from the breakage part detector. Further, in a cold tandem rolling method, the emergency stop device is operated to stop the rolling when a broken part is detected by the breakage part detector, in implementing cold rolling on a strip using the cold tandem rolling equipment.SELECTED DRAWING: Figure 1

Description

The present invention relates to a cold tandem rolling facility and a rolling method for continuously cold-rolling a hot-rolled steel strip (hot-rolled steel strip) in a steel sheet manufacturing process, particularly high alloy steel and the like. The distribution of deformation resistance in the plate width direction relates to a cold tandem rolling facility and a cold tandem rolling method suitable for continuous cold rolling of hot-rolled strips generated non-uniformly in the longitudinal direction. ..

Specific examples of the hot-rolled strip in which the distribution of deformation resistance in the plate width direction is non-uniform in the longitudinal direction include high-strength steel sheets (high-tensile steel sheets), stainless steel sheets, and electromagnetic steel sheets. There is. In the manufacturing process of hot-rolled steel strips (hot-rolled steel strips), steel slabs are hot-rolled by a rough rolling mill and a finishing rolling mill, wound around a coil, and the coil is cooled in the atmosphere. There is a manufacturing process in which rough rolling is omitted, hot rolling equivalent to finish rolling is performed, the coil is wound around a coil, and the coil is cooled in the atmosphere. In addition, thin-walled slabs (thin-walled slabs) manufactured by the double-roll type continuous casting method or belt-type continuous casting method known as the thin plate continuous casting and rolling method are immediately equivalent to a finish rolling mill without rough rolling. The manufacturing process of rolling down the coil with an in-line mill and then cooling the coil in the air, and the continuous continuous casting, hot rough rolling, and hot finish rolling. There is also a process.

Hereinafter, as an example here, a manufacturing process including a step of hot rolling a steel slab with a rough rolling mill and a finishing rolling mill, winding it around a coil, and then cold rolling a strip coil obtained by cooling the coil in the atmosphere. A case of manufacturing a non-directional electromagnetic steel sheet will be described as an example.

For example, Patent Document 1 describes in terms of mass% C ≦ 0.008, 2 ≦ Si + Al ≦ 3, 0.02 ≦ Mn ≦ 1.0, S ≦ 0.003, N ≦ 0.002, Ti ≦ 0.003. , 0.001 ≤ REM ≤ 0.02, and 0.3 ≤ Al / (Si + Al) ≤ 0.5, and heat the non-directional electromagnetic steel plate slab containing the balance Fe and unavoidable impurities. By performing hot finish rolling in a temperature range where the interfinish rolling temperature is 1050 ° C or higher, the subsequent non-injection time is set to 1 second or more and 7 seconds or less, and winding is performed at 700 ° C or lower by water injection cooling. A manufacturing method that replaces the hot rolling annealing step by a cooling process after hot finish rolling is disclosed.

Japanese Unexamined Patent Publication No. 2010-242186 Japanese Unexamined Patent Publication No. 60-46804 JP-A-2002-239617 Japanese Unexamined Patent Publication No. 2003-340510 Japanese Unexamined Patent Publication No. 3-60810 Japanese Unexamined Patent Publication No. 2014-8520 Japanese Unexamined Patent Publication No. 10-128421

"Illustrated electromagnetic steel plate" (Shin Nihon Steel Co., Ltd., 1994), p.67

However, as shown in Patent Document 1, for example, a self-annealing coil for a non-directional electromagnetic steel sheet wound around a coil by omitting the hot coil annealing step by self-annealing in the cooling process after continuous hot rolling is provided. It was recognized that there are the following problems in continuous cold rolling in a cold tandem rolling mill after pickling.

1) The hot-rolled steel strip that has been hot-rolled is usually wound into a coil at, for example, 700 ° C. or lower, and then cooled in the atmosphere as it is in the coil. In such a cooling process, the cooling rate varies depending on the position of the material in the coil. Specifically, the cooling rate of the outer peripheral portion of the coil is higher than the cooling rate of the inner peripheral portion, and the cooling rate of the end portion (edge portion) in the plate width direction is lower than that of the portion closer to the center portion in the plate width direction. The speed increases.
Due to such variations in the cooling rate in the coil, non-uniformity of the material, especially in the strength, occurs in the coil in the longitudinal direction and the width direction of the plate, and eventually, the deformation resistance in the cold becomes non-uniform. .. Here, such a coil is referred to as a self-annealing coil. The material (steel type) of this self-annealed coil is not limited to the above-mentioned non-directional electromagnetic plate, and non-uniformity of the material, particularly non-uniformity of strength occurs in the plate longitudinal direction and the plate width direction in the coil, and eventually It means a steel type in which non-uniform deformation resistance occurs in the cold.

2) In this way, in the self-annealed coil, the non-uniformity of the material in the longitudinal direction and the plate width direction in the coil is near the outer circumference and the edge of the self-annealed coil (the widthwise end of the wound hot-rolled steel strip). Although it occurs in the vicinity), the non-uniformity is remarkable in the region from the end (edge) in the plate width direction to the inside of 150 mm to 250 mm in 2 to 3 rounds on the outer peripheral side of the self-annealing coil. In the region, the strength of the end portion in the plate width direction of the strip may be about 10% to 20% higher than the strength of the central portion in the plate width direction.

3) When a self-annealed coil having non-uniform material as described above is continuously welded to form a strip, pickled and cold tandem rolled, the above-mentioned is used at the first stand of the cold tandem rolling mill. Since the difference in deformation resistance at the non-uniform material portion, that is, the deformation resistance at both ends in the plate width direction is larger than the deformation resistance at the center portion in the plate width direction, the shape of the rolled plate becomes medium elongation, and therefore, so-called Rolling may occur and plate breakage may occur.

4) If plate breakage occurs due to drawing due to medium elongation, the work roll at the rolling stand in the cold tandem rolling mill is often damaged. In that case, it is necessary to stop rolling and replace the work roll, which greatly reduces the productivity.

5) Furthermore, when the plate breakage due to drawing is severe (in the case of plate breakage due to severe medium elongation), it is necessary to replace not only the work roll but also the intermediate roll or backup roll in contact with the work roll. Become.

6) Especially at the time of high-speed rolling, the plate breakage due to drawing is severe, and it may take a long time of about 10 hours to recover, which causes a significant decrease in productivity.

As described above, with respect to the self-annealed coil, in the subsequent cold tandem rolling, plate breakage due to drawing is likely to occur, and there is a strong possibility that productivity will be hindered.
Therefore, in cold tandem rolling of a self-annealing coil, a cold tandem rolling facility and a rolling method capable of preventing plate breakage have been strongly demanded.

In general, it is known to control the plate shape during rolling in order to prevent drawing in the rolling mill. That is, a shape detector is installed on the exit side of the rolling mill to measure the rolled plate shape, and the shape control end of the rolling mill (for example, the work piece) so as to fit in the desired plate shape, for example, not to have a medium elongation shape. It is known to control roll bender force) (for example, Patent Document 2). Generally, such shape control is performed at the final stand.

Further, Patent Document 3 proposes a method of measuring the rolled plate shape by installing a shape detector on the exit side of the rolling mill at the first stand of the cold tandem rolling mill and controlling the shape. Further, Patent Document 4 proposes a method in which a shape detector is installed on the exit side of the rolling mill in the first stand and the second stand of the cold tandem rolling mill to measure the rolled plate shape and control the shape. ing. Further, Patent Document 5 proposes a method in which a shape detector is installed on the exit side of a rolling mill in all stands of a cold tandem rolling mill to measure the rolled plate shape and control the shape.

On the other hand, Patent Document 6 discloses a shape control method when there is a non-uniform deformation resistance distribution in the plate width direction. That is, in Patent Document 6, the yield stress in the width direction of the hot-rolled steel strip is measured in advance at the positions of the tip portion, the central portion, and the tail end portion in the longitudinal direction of the hot-rolled steel strip, and the deformation resistance distribution pattern is investigated. A method of performing shape presetting of a rolling mill based on the result (different shape presetting is performed at the positions of the tip portion, the center portion, and the tail end portion in the longitudinal direction of the hot-rolled steel strip) is disclosed.

In the shape control method disclosed in Patent Documents 2 to 5, the plate shape is measured by a shape detector installed on the outlet side of any one or more rolling mill stands, and the measured plate shape is the target. This is a method of feedback-controlling the shape control end of the rolling mill stand so as to pass through. Although this method is effective for hot-rolled steel strips in which drawing does not easily occur even if the plate shape changes and relatively gradual changes such as thermal crowns, self-annealing is mainly the subject of the present invention. It is recognized that the coil is not always effective.

The reason is that in the self-annealed coil in which the hot coil annealing step is omitted, the deformation resistance distribution is highly non-uniform and changes rapidly in the longitudinal direction, so that the shape after rolling also changes sharply. However, in the shape control method by feedback control as shown in Patent Documents 2 to 5, the time wasted between the hot-rolled steel strip from a certain rolling mill stand to the shape detector on the exit side of the rolling mill stand. There is. Therefore, when the shape change is large and sudden, the feedback control cannot keep up with the time.

When the present inventors investigated the data of the plate breakage of the first stand due to the drawing of the self-annealed coil, the edge elongation with a steepness of 1% took about 2 seconds at a rolling speed of 200 m / min at the first stand. It has been confirmed that the steepness changes from 2% to medium elongation, and as a result, drawing occurs and the plate may break. In this case, since the shape detector is installed at a location 3 m away from the roll bite outlet of the first stand (it is impossible to make it less than 3 m due to space), it takes about 1 second to detect the shape. However, even if the shape control is started after that, it takes about 1 second, so that it takes about 2 seconds from the roll bite to actually perform the shape control. Therefore, it is difficult to prevent the plate from breaking because it is not in time for the above-mentioned sudden shape change. At this time, if the rolling speed at the first stand is reduced to 100 m / min, the relative rolling length at which shape control is started is shortened by half, but the wasted time until the shape is detected is doubled. Therefore, it is difficult to prevent plate breakage even if the rolling speed is lowered.

On the other hand, the yield stress in the width direction of the material at the tip portion, the center portion, and the tail end portion in the longitudinal direction of the original plate coil, which is disclosed in Patent Document 6, is measured in advance to investigate the deformation resistance distribution pattern, and the investigation result ( The method of performing shape presetting (feed forward control) on the rolling mill stand based on the prediction result) is effective for a material having reproducibility for each coil of the hot-rolled steel strip. However, the self-annealed coil targeted by the present invention has a change in plate shape during cold rolling depending on the plate shape of hot-rolled finish, scale, and coil cooling conditions after winding (coil arrangement position, seasonal factors, etc.). The situation is very different. For this reason, there is a large variation in the prediction results, and it cannot be said that there is practical reproducibility. That is, it is difficult to pattern the deformation resistance distribution over the entire coil length based on the prediction survey. By the way, if an inappropriate pattern is input, there is a risk of promoting medium elongation and inducing plate breakage.

In addition, without predicting the deformation resistance distribution pattern as described above, it is conceivable to preset the rolling mill stand to the edge elongation shape so that the deformation resistance distribution does not become medium elongation even if the deformation resistance distribution changes. In this method, the non-uniformity of the deformation resistance distribution of the hot-rolled steel strip is not so large, the deformation resistance does not change so much in the length direction of the hot-rolled steel strip, and the material does not vary from coil to coil of the hot-rolled steel strip. Is effective to some extent. However, in the self-annealed coil mainly targeted in the present invention, the distribution of the deformation resistance distribution in the plate width direction varies greatly in the length direction of the hot-rolled steel strip. Therefore, if presets are made so that the edge elongation occurs even in places where the deformation resistance distribution is uneven (the plate edge is hard) in order to prevent medium elongation, the edge elongation occurs where the deformation resistance distribution is uniform (the plate edge is hard). May become too large, and conversely, drawing may occur due to excessive edge elongation, which may induce plate breakage.

As described above, conventionally, when cold tandem rolling is performed on a coil having a large non-uniform deformation resistance distribution in the longitudinal direction and the width direction of a hot-rolled steel strip, such as a self-annealed coil, the occurrence of plate breakage is surely prevented. The actual situation is that the control method to be used has not been established yet.

By the way, in cold tandem rolling, a tension meter is installed between each rolling mill stand, and the plate tension between the stands is constantly monitored during rolling to detect the change in tension, resulting in a non-tensioned state. Conventionally, rolling is stopped urgently by recognizing that the plate is broken (see, for example, Patent Document 7).
However, even if the occurrence of plate breakage is detected by the tension between the stands and the rolling is stopped urgently in this way, the broken portion suddenly jumps due to the plate breakage, or two sheets are bitten due to the bending of the broken portion. The work roll, backup roll, or intermediate roll is often scratched at the stand where the break occurs and the stand after which the break has passed. Therefore, as already described, it takes a long time to replace the work roll and the like, and it also takes a considerable amount of time to process the plate breakage portion in the rolling mill. As a result, it took an extremely long time from the time when the fracture was detected and the emergency stop was performed until the rolling was restarted (restarted), and it was unavoidable that the productivity was significantly reduced.

By the way, if the occurrence of fracture is predicted at an early stage (that is, the sign of fracture is detected) and the rolling is stopped urgently, it is considered possible to minimize the decrease in productivity due to fracture. .. However, as described above (for example, as shown in Patent Document 7), the method of monitoring the tension between the stands, detecting the breakage when the tension becomes zero, and making an emergency stop is completely complete. It was an emergency stop after the fracture occurred, and the occurrence of the fracture could not be predicted at an early stage, and as mentioned above, a significant decrease in productivity was unavoidable.

The present invention has been made in view of the above problems, and an object of the present invention is to cool a coil having a large non-uniform deformation resistance distribution in the longitudinal direction and the width direction of a hot-rolled steel strip, such as a self-annealed coil. Even in inter-tandem rolling, the possibility of plate breakage is predicted before plate breakage occurs, and rolling can be stopped urgently at that timing, thereby reducing plate breakage-productivity associated with emergency stoppage. It is an object of the present invention to provide a cold tandem rolling facility and a cold tandem rolling method capable of suppressing a decrease to a minimum.

When the present inventors investigated the state of plate fracture in cold tandem rolling of a self-annealed coil having a large non-uniform deformation resistance distribution, the strip fracture did not occur suddenly, but first a relatively small hole-shaped fractured portion. It was recognized that (hole-shaped voids that did not break) occurred, and then, as the rolling progressed, the strip broke from the vicinity of the broken part. Therefore, we recognized that if the occurrence of a torn part before breaking is detected and rolling is stopped urgently, damage due to breaking (damage to the roll) can be minimized and a significant decrease in productivity can be suppressed. This has led to the present invention.

Specific aspects of the cold tandem rolling equipment and the cold tandem rolling method of the present invention are shown below.

The cold tandem rolling equipment of the basic aspect (first aspect) of the present invention is
Of the plurality of rolling mill stands in the cold tandem rolling mill in which a plurality of rolling mill stands are arranged in series, at least on the outlet side of the first rolling mill stand located on the most upstream side, of the strips to be rolled. A breakage detection device for detecting the occurrence of a breakage that has not reached breakage is provided, and an emergency stop device for stopping the rolling operation of the cold tandem rolling mill based on the detection result by the breakage detection device is provided. It is characterized by being rolled.

Further, the cold tandem rolling equipment according to the second aspect of the present invention is provided.
In the cold tandem rolling equipment of the first aspect,
The tear portion detection device is an optical detection device.

Further, the cold tandem rolling equipment according to the third aspect of the present invention is
In the cold tandem rolling equipment of the first aspect,
The tear portion detection device is an acoustic detection device.

Further, the cold tandem rolling method according to the fourth aspect of the present invention is:
When the strip is cold-rolled by the cold tandem rolling equipment according to any one of the first to third aspects, the strip is cold-rolled.
When a torn portion is detected by the torn portion detecting device, the emergency stop device is operated to stop rolling.

According to the cold tandem rolling equipment and the cold tandem rolling method of the present invention, a hot-rolled steel strip having a non-uniform distribution of deformation resistance in the plate width direction in the longitudinal direction, such as a self-annealed coil, is cold. Even when rolling with a tandem rolling mill, a broken portion that does not lead to plate breakage is detected at least on the outlet side of the first rolling mill stand on the most upstream side, and rolling is stopped early in an emergency to roll after an emergency stop. The replacement work can be simplified and shortened, and the processing of the broken portion in the rolling mill is not required, so that the decrease in productivity can be minimized.

It is a figure which shows an example of the manufacturing line of the non-oriented electrical steel sheet which incorporated the cold tandem rolling equipment which concerns on one Embodiment of this invention.

<Embodiment of cold tandem rolling equipment>
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 shows an example of a manufacturing line for an electromagnetic steel sheet incorporating a cold tandem rolling facility according to an embodiment of the present invention.

In FIG. 1, the coils C1 and C2 are, for example, hot-rolled plates (self-annealed coils) for non-directional electromagnetic steel sheets obtained by omitting the hot coil annealing step by self-annealing in the cooling process of continuous hot-rolling. It is an annealed thing.

Here, the composition of the hot-rolled sheet for the non-directional electromagnetic steel plate and the cooling conditions after hot rolling for self-annealing are basically not limited, and the point is that the hot-rolled sheet annealing step is omitted. The component composition and cooling conditions are sufficient so that the performance as a non-directional electromagnetic steel sheet is finally guaranteed. For example, the component composition and cooling conditions described in Patent Document 1 are preferable. is there.

That is, in terms of mass%, C ≦ 0.008%, 2% ≦ (Si + Al) ≦ 3.0%. It contains 02% ≤ Mn ≤ 1.0%, S ≤ 0.003%, N ≤ 0.002%, Ti ≤ 0.003%, 0.001% ≤ REM ≤ 0.02%, and further. Satisfy the relationship of 3% ≤ Al / (Si + Al) ≤ 0.5%, and use a slab for non-directional electromagnetic steel sheets containing the balance Fe and unavoidable impurities so that the hot finish rolling temperature is 1050 ° C or higher. A self-annealed coil is preferable, in which hot finish rolling is performed in a temperature range, the subsequent non-injection time is 1 second or more and 7 seconds or less, and winding is performed at 700 ° C. or less by water injection cooling.

In FIG. 1, the self-annealing coils C1 and C2 as described above are supplied to the coil dispenser 1. The plate dispensed from the self-annealing coils C1 and C2 by the coil dispenser 1 is a continuous strip in which the tail end of the plate from the leading coil and the tip of the plate from the trailing coil are welded by the welding machine 2. (Self-annealed strip) becomes S and is sent to the looper 3. In the following. The self-annealed strip S dispensed from the self-annealed coils C1 and C2 and continuous is sometimes referred to simply as a strip or a self-annealed plate.
The looper 3 is controlled so that there is no stagnation in the supply of strips in the downstream process even when there is no payout during coil joining in the welding machine 2 (that is, when the strips are stopped running). The self-annealing coils C1 and C2 supplied to the coil dispenser 1 may be preheated to a temperature of 60 ° C. or higher in a hot bath or the like.

The self-annealed strip S that has passed through the looper 3 is supplied to the pickling facility 4. In this pickling facility 4, the surface scale of the self-annealing coil is removed (melted). In order to increase the melting efficiency before pickling, a rolling mill that cracks the surface of the self-annealed strip S, a leveler or tension leveler, a shot blast (dry or wet), or a grinder may be installed.

The self-annealed strip S, which has been pickled to remove surface scale, is sent to a cold tandem rolling mill 7 and rolled to a thinner plate thickness.

In the present embodiment, the cold tandem rolling mill 7 is composed of five rolling mill stands 7a to 7e arranged in series, and the first stand 7a to the fifth stand 7e are, for example, quadruple rolling mills, respectively. It is composed of (4 Hi mill).
Further, in the cold tandem rolling mill 7, although not shown, rolling lubricating oil that is made into an emulsion by mixing rolling lubricating oil called coolant with water is supplied on the inlet side and the outlet side of each stand. .. The supplied coolant is collected in a tank (not shown), and resuscitation lubrication is performed again to be supplied to each stand.

In the cold tandem rolling mill 7, for example, a self-annealed strip for non-oriented electrical steel sheets having a plate thickness of 2.3 mm and a plate width of 1200 mm is rolled to a plate thickness of 0.3 mm. As the coolant, for example synthetic ester (hindered complex esters) based oil and the rolling lubricant concentration of 2% at a temperature 60 ° C., in each stand 1 to 3 m 3 / ^min supply (inlet side and outlet side of the (Total), rolling lubrication and work roll cooling are performed.

The work roll diameters of the rolling mill stands 7a to 7e are, for example, 500 mm to 700 mm, the backup roll diameter is, for example, 1300 mm to 1600 mm, and the body length is, for example, 2000 mm.

On the exit side of the first rolling mill stand 7a of the cold tandem rolling mill 7, a tear that detects a torn portion (hole-shaped void) caused by drawing or the like due to rolling of the first rolling mill stand 7a is detected. The unit detection device 5 is installed.

Here, the torn portion means a hole-shaped portion that penetrates in the thickness direction of the plate within the plate width of the strip. In other words, the strip penetrates in the thickness direction of the strip at a portion where the front portion in the rolling traveling direction and the rear portion in the rolling traveling direction of the strip are not completely divided (broken) during rolling (non-breaking state). Means the part. The shape and size of the torn part vary, but the planar shape of the torn part due to the drawing is usually crescent-shaped, semi-circular, circular, oval, or crack-shaped, and the size is initially In the state, it is about 10 mm × 20 mm on average.

The specific configuration of the broken portion detection device 5 is not particularly limited, but an optical or acoustic detector can be used. In the present embodiment, the optical detector detects light passing through the broken portion. It is used as a detector. That is, in the present embodiment, as shown in FIG. 1, the light source 5A that radiates light from one plate surface side of the strip S to the plate surface over the entire plate width and the inside of the torn portion within the plate width are The broken portion detecting device 5 is composed of a light receiver 5B that receives the passed light on the other plate surface side of the strip.

The optical broken portion detecting device 5 is not limited to the method of detecting the light passing through the broken portion as described above, and may be configured to detect the broken portion by, for example, image processing. That is, using a moving image imaging device (video camera) that continuously captures the plate surface (within the plate width) of the strip or a still image imaging device (steel camera) that captures intermittently, the captured image is immediately image-processed (for example). It may be configured to detect a broken portion from the binarized image). The light source is not limited to visible light, and infrared rays, X-rays, and γ-rays may be used.

Further, as the acoustic type tear detection device 5, a gas such as compressed air is blown onto the plate surface of the strip over almost the entire area in the width direction of the strip to generate minute vibrations in the strip, and radiation from the strip surface at that time is generated. A structure that detects a broken portion by frequency-analyzing the sound (vibration sound) can be used. That is, if the vibration sound is frequency-analyzed by blowing compressed air or the like as described above onto the strip, the present inventor finds that when there is a broken portion, a peak appears in a frequency band different from that when there is no broken portion. Etc. have been confirmed.

Specifically, when there is no broken portion, vibration occurs in a frequency in the middle to high frequency band, and a relatively high sound is generated as a vibration sound. On the other hand, if there is a broken portion, in addition to the vibration of the frequency in the middle to high frequency band, the vibration of the low frequency is added, and the relatively low sound is mixed. Therefore, for example, an acoustic source (for example, a compressed air generator) is installed toward the plate surface of the strip, and a sound collector for collecting vibration sound is installed, and the collected sound is analyzed by a frequency analyzer. Then, when the sound in the low frequency range exceeds a predetermined level (threshold value), it can be determined that there is a broken portion.

In the self-annealed strip in which a plurality of self-annealed coils are connected by welding, a punch hole is formed near the welded portion or a smooth arc shape is formed at the end portion in the plate width direction near the welded portion for tracking of each coil. In some cases, a notch is formed and then subjected to cold tandem rolling in that state. In that case, when the punched holes and cut portions pass through the torn portion detecting device, it is expected that those punched holes and cut portions will be mistaken for the torn portions. In order to avoid this, the positions of the punched holes and cut portions may be tracked during continuous rolling, and the signal processing may be performed so as to ignore the detection signal when those portions pass through the breakage detection device. preferable.

Further, the cold tandem rolling mill 7 is provided with an emergency stop device 6 for urgently stopping the cold tandem rolling mill 7 based on the detection signal when the broken portion detecting device 5 detects the broken portion. In short, if the emergency stop device 6 is configured to control the cold tandem rolling mill 7 so as to urgently stop the rolling of the strip S by the cold tandem rolling mill 7 when a breaking portion detection signal is given. Frequently, for example, a control is performed in which the rotary drive of the work rolls of the rolling mill stands 7a to 7e of the cold tandem rolling mill 7 is stopped by the detection signal of the torn portion to stop the plate passing (then each rolling mill stand 7a to 7a to The rolling of 7e is released). As an emergency stop method in this case, for example, as disclosed in Patent Document 7, the strip threading is adjusted so that the tension of the strip between the rolling mill stands is the tension at the steady state at the time of sheeting. It is preferable to stop.

In some cases, the emergency stop device 6 may control to immediately release the rolling reduction of the work rolls of the rolling mill stands 7a to 7e by the detection signal of the torn portion.

Downstream of the cold tandem rolling mill 7, a cutting machine 8 for cutting continuous and rolled self-annealed strips is installed, and downstream of the cutting machine 8 is a caroselle that winds up continuous and rolled self-annealed strips. Reel 9 is deployed. Although not shown, the coil wound and cut by the roselle reel 9 is discharged from the roll, placed on a conveyor, and carried out to a factory or the like in the next process.

Next, an embodiment of the cold tandem rolling method of the present invention will be described.

<Embodiment of cold tandem rolling method>
The cold tandem rolling method of the embodiment basically uses a cold tandem rolling facility as shown in FIG. 1, for example, to continuously cold a self-annealed strip in which a self-annealed coil is continuous by welding. In rolling, when a broken portion is detected by the broken portion detecting device, the emergency stop device is operated to stop rolling.

In the cold tandem rolling equipment shown in FIG. 1, the breakage detection device 5 is installed on the exit side of the first rolling mill stand 7a (upstream of the second rolling mill stand 7b). Therefore, at the time (timing) when the fractured portion due to the drawing generated during rolling on the first rolling mill stand 7a reaches the exit side of the first rolling mill stand 7a and reaches the fractured portion detecting device 5 and is detected, the rolling is performed. It will be an emergency stop.

Here, if the fractured portion generated at the first rolling mill stand passes through each rolling mill stand in the subsequent stage (after the second rolling mill stand) without urgently stopping the rolling at the above timing, the fractured portion Rapidly expands and progresses, leading to plate breakage. As a result, in each stand after the second rolling mill stand, the work roll and the like are severely damaged due to sudden jumping of the broken portion and double biting due to bending of the broken portion. However, in the case of the present embodiment, when a broken portion is detected on the exit side of the first rolling mill stand 7a (the entrance side of the second rolling mill stand 7b), the rolling is urgently stopped immediately, so that the second rolling mill It is possible to prevent the work rolls of the stands 7b and subsequent stands from being damaged by the broken portion of the plate.
Therefore, it is not necessary to replace the work rolls of each stand after the second rolling mill stand, and the time required for the roll replacement becomes unnecessary or shortened. At the same time, it is not necessary to treat the plate breakage portion in the cold tandem rolling mill. Therefore, the time from the emergency stop to the restart (the rolling stop time is also significantly shortened in total, and the productivity can be greatly improved.

In the present embodiment, since the fractured portion generated during rolling on the first rolling mill stand is detected on the exit side of the first rolling mill stand and is urgently stopped, the fractured portion of the first rolling mill stand causes the first rolling mill stand. The work roll (and in some cases the work roll of the second rolling mill stand) may be damaged. However, even in that case, as described above, the work rolls of the stands after the first rolling mill stand (or after the second rolling mill stand) are often not damaged, so that after the emergency stop, the first rolling mill stand Only the work rolls (or the work rolls on the first and second stands) need to be replaced. Therefore, compared to the case where the rolls of each stand (for example, all stands) after the second rolling mill stand (or after the third rolling mill stand) are replaced in addition to the rolls of the first rolling mill stand, after an emergency stop. The work time required for roll replacement is greatly reduced. Further, in the case of the present embodiment, the damage to the roll of the first rolling mill stand due to the occurrence of the torn portion in the first rolling mill stand is much lighter than the damage due to the plate breakage. Therefore, there is little risk that the backup roll and the intermediate roll of the first rolling mill stand will be damaged, which also contributes to shortening the roll replacement work after an emergency stop.

Hereinafter, Examples (Example 1, Example 2) and Comparative Examples relating to the cold tandem rolling method of each embodiment of the present invention will be described.
Each of the examples and comparative examples was carried out in a cold tandem rolling apparatus having the configuration shown in FIG. That is, the cold rolling mill was composed of the first to fourth rolling mill stands, and each rolling mill stand was composed of a quadruple rolling mill (4 Hi mill).

The strips subjected to tandem cold rolling in each example and comparative example are self-annealed strips for non-directional electromagnetic steel sheets having a plate thickness of 2.3 mm and a plate width of 1200 mm, and have a mass% of C: 0.007%. (Si + Al): 2.5%, Mn: 0.5%, S: 0.001%, N: 0.001%, Ti: 0.001%, REM: 0.01%, and further, Al / (Si + Al): Hot finish rolling such that the hot finish rolling temperature is 1090 ° C. using a slab for non-directional electromagnetic steel sheet that satisfies the relationship of 0.4% and contains the balance Fe and unavoidable impurities. After that, the non-injection time was set to 6 seconds, and the film was wound at 680 ° C. by water injection cooling.

The strips dispensed from such a coil (self-annealed coil) were made continuous by welding and rolled as self-annealed strips by the above-mentioned cold tandem rolling mill to a plate thickness of 0.3 mm. The rolling speed of the final stand at the time of coil switching was 250 m / min, and the maximum rolling speed of the final stand was 1100 m / min. Further, as shown in Table 1 below, the tension between the stands was set to 50 to 250 MPa.

As the broken portion detecting device, in Example 1, an optical detector that detects the passage of light in the broken portion as shown in FIG. 1 is used, and in Example 2, it is detected by frequency analysis of an acoustic signal. An acoustic detector was used, and in both Examples 1 and 2, a breakage detector was installed between the exit side of the first rolling mill stand and the entrance side of the second rolling mill stand. Oita.

The modes of measurement and control in each of the examples and comparative examples are as follows.
-Comparative example: This is an example corresponding to the conventional general rolling method, and even if there is a deformation resistance distribution in the plate width direction, the self-annealed strip is rolled as it is without detecting the broken portion and the emergency stop accompanying it. ..
Example 1: An optical tear detection device was installed on the exit side of the first stand, and when the tear of the strip was optically detected, rolling was urgently stopped.
Example 2: An acoustic tear detection device was installed on the exit side of the first stand, and when a tear in the strip was detected by frequency analysis, rolling was urgently stopped.

As described above, the self-annealed strips were rolled for 500 coils each according to Examples and Comparative Examples. In each example, the occurrence of plate breakage and the time from the time of emergency stop to restart (rolling stop time: mainly the time required for roll replacement, but if plate breakage occurs, the broken part is treated. The time required is added). The results are as follows.

-Comparative example (conventional technique): Plate breakage occurred with a probability of about 3%. The rolling stop time was 4 to 18 hours. Here, when the plate is broken during high-speed rolling, the surface of the backup roll may also be damaged. In that case, in addition to processing the broken plate (manual work) and replacing the work roll, the crotch of the backup roll Was also required, and it took a long time of about 18 hours.
-Example 1 and Example 2: No plate breakage occurred. As a result, the treatment of the broken portion was not required, and the rolling stop time was suppressed to 30 minutes or less at the maximum. Here, there were few cases where the work rolls needed to be replaced, but in rare cases it was necessary to rearrange the work rolls of the first stand, or the first stand and the second stand. Even in that case, the rolling stop time was about 30 minutes. No cases were found in which the surface of the backup roll was damaged.

Although the preferred embodiments of the present invention have been described in detail with reference to the accompanying drawings, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical idea described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

For example, in the above embodiment, a self-annealed material of non-oriented electrical steel sheet is targeted, but the present invention is not limited to such an example. For example, directional electromagnetic steel sheets, other high-strength steels, stainless steel sheets, etc. may be targeted, and not only self-annealed hot-rolled strips, but also large non-uniform deformation resistance in the strip length direction and plate width direction. If there is, it can be applied to prevent plate breakage during cold tandem rolling.

Further, in the above-mentioned example, the quadruple rolling mill (4Hi mill) is used as each rolling mill stand, but the present invention is not limited to this, and for example, a 6-fold rolling mill (6Hi mill) may be used.

Further, in the above-described embodiment, the breakage detection device is provided only on the outlet side of the first rolling mill stand, but in some cases, not only on the outlet side of the first rolling mill stand but also after the second rolling mill stand. A broken part detection device is also installed on the outlet side of any one or more of the stands (excluding the final stand), and when any of the broken part detection devices detects a broken part, the detection is performed. Rolling may be stopped urgently based on the signal.

Although the preferred embodiments and experimental examples of the present invention have been described above, these embodiments and experimental examples are merely examples within the scope of the gist of the present invention and do not deviate from the gist of the present invention. It is possible to add, omit, replace, and make other changes to the configuration. That is, the present invention is not limited by the above description, but is limited only by the scope of the appended claims, and of course, it can be appropriately modified within the scope.

C1, C2 Self-annealed coil S Self-annealed strip 1 Coil dispenser 2 Welder 3 Looper 4 Pickling equipment 5 Breakage detector 5A Light source 5B Receiver 6 Emergency stop device 7 Cold tandem rolling mill 7a, 7b, 7c, 7d , 7e Cold tandem rolling mill rolling mill stand 8 cutting machine 9 carousel reel

Claims (4)

Of the plurality of rolling mill stands in the cold tandem rolling mill in which a plurality of rolling mill stands are arranged in series, at least the strip to be rolled is located on the outlet side of the first rolling mill stand located on the most upstream side. A breakage detection device for detecting the occurrence of a breakage that has not reached breakage is provided, and an emergency stop device for urgently stopping rolling by a cold tandem rolling mill based on the detection result by the breakage detection device is provided. Cold tandem rolling equipment characterized by being In the cold tandem rolling equipment according to claim 1.
A cold tandem rolling facility in which the breakage detection device is an optical detection device. In the cold tandem rolling equipment according to claim 1.
A cold tandem rolling facility in which the breakage detection device is an acoustic detection device. When the strip is cold-rolled by the cold tandem rolling equipment according to any one of claims 1 to 3.
A cold tandem rolling method, characterized in that when a broken portion is detected by the broken portion detecting device, the emergency stop device is operated to stop rolling.

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