JP2021030239A - 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 is prevented so that stable cold tandem rolling can be implemented even on a strip of a self-annealing material.SOLUTION: In the cold tandem rolling equipment, a deformation resistance distribution measuring instrument is arranged on an upstream side of a cold tandem rolling mill, in order to measure a deformation resistance distribution in the longer direction and the plate width direction by measuring a distribution in the plate width direction for a construction material correlated to deformation resistance of a strip to be rolled. The cold tandem rolling equipment comprises: a heating device for generating a temperature distribution in a strip plate width direction between the deformation resistance distribution measuring instrument and a first rolling mill stand on the basis of the deformation resistance distribution; a calculation device for calculating a control amount of the heating device required for obtaining a plate width direction temperature distribution for making the deformation resistance distribution uniform in the strip plate width direction, on the basis of a measured value of the deformation resistance distribution measuring instrument; and a heating control device for controlling the control amount of the heating device on the basis of the calculated control amount.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, in particular, a high alloy rope or 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.
Generally, in the production of non-directional electromagnetic steel sheets, a cast plate (slab) obtained by continuous casting is heated and continuously hot-rolled to obtain a hot-rolled steel strip having a predetermined plate thickness, followed by hot-rolled steel. Generally, the band is subjected to continuous annealing (hereinafter referred to as hot coil annealing), then pickled and cold-rolled, and surface-treated (for example, Non-Patent Document 1). In such a conventional general manufacturing method, the number of steps is large, which inevitably leads to high cost. Therefore, recently, in order to reduce the manufacturing cost of non-oriented electrical steel sheets, for example, efforts have been made to omit the hot coil annealing step of the hot-rolled steel strip. That is, it is a method of omitting the hot coil annealing process by appropriately controlling the conditions of the finish rolling process of the hot-rolled steel strip and the subsequent cooling process in the hot rolling process and self-annealing in the cooling process. ..

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 further, the non-directional electromagnetic steel plate slab that satisfies the relationship of 0.3 ≤ Al / (Si + Al) ≤ 0.5 and contains the balance Fe and unavoidable impurities is heated. By performing hot finish rolling in a temperature range where the finish 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-rolled sheet annealing step (hot coil annealing step) by the 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 Jikkenhei 3-128850 Gazette Japanese Unexamined Patent Publication No. 2-210258

"Illustrated Electrical Steel Sheets" (Nippon Steel Corporation, 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 in the vicinity of 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, there has been a strong demand for cold tandem rolling equipment and rolling methods that prevent plate breakage of the self-annealing coil in cold tandem rolling.

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 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.

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. It is an object of the present invention to provide a cold tandem rolling facility and a cold tandem rolling method that can surely prevent the occurrence of plate breakage and enable stable rolling in the inter-tandem rolling.

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
Strips upstream of a cold tandem rolling mill consisting of multiple rolling mill stands arranged in series by continuously measuring the distribution in the strip width direction for materials that correlate with the deformation resistance of the strip to be rolled. A deformation resistance distribution measuring device for measuring the deformation resistance distribution in the longitudinal method and the width direction of the strip plate is provided.
Further, based on the measured deformation resistance distribution, the temperature distribution is distributed in the strip plate width direction between the deformation resistance distribution measuring instrument and the first rolling mill stand located on the most upstream side of the plurality of rolling mill stands. A heating device to generate and
Calculation for calculating the control amount of the heating device required to obtain the temperature distribution in the plate width direction so that the deformation resistance distribution in the strip plate width direction becomes uniform based on the measured value of the deformation resistance distribution measuring device. With the device
It is characterized by including a heating control device that controls the control amount of the heating device based on the calculated control amount.

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,
A temperature detector for measuring the temperature distribution of the strip in the plate width direction is provided between the heating device and the first rolling mill stand.

Further, the cold tandem rolling method according to the third aspect of the present invention
Strips by continuously measuring the distribution in the strip width direction for materials that correlate with the deformation resistance of the strips being rolled upstream of a cold tandem rolling mill consisting of multiple rolling mill stands arranged in series. Measure the deformation resistance distribution in the longitudinal method and strip plate width direction,
Further, before the strip whose deformation resistance distribution has been measured is rolled by the first rolling mill stand located on the most upstream side of the plurality of rolling mill stands, the strip is at least at the end in the plate width direction by a heating device. The rolling mill is heated to generate a temperature distribution in the plate width direction.
Moreover, based on the measured deformation resistance distribution, the control amount of the heating device required to obtain the temperature distribution in the plate width direction so that the deformation resistance distribution in the strip plate width direction becomes uniform was calculated and calculated. It is characterized in that the controlled amount of the heating device is controlled based on the controlled amount.

Further, the cold tandem rolling method according to the fourth aspect of the present invention is:
Strips by continuously measuring the distribution in the strip width direction for materials that correlate with the deformation resistance of the strips being rolled upstream of a cold tandem rolling mill consisting of multiple rolling mill stands arranged in series. Measure the deformation resistance distribution in the longitudinal method and strip plate width direction,
Further, the strip whose deformation resistance distribution has been measured is at least end in the plate width direction by a heating device before being rolled by the first rolling mill stand located on the most upstream side of the plurality of rolling mill stands. The region is heated to generate a temperature distribution in the strip width direction, and the temperature distribution in the strip width direction is measured between the heating device and the entrance side of the first rolling mill stand.
Based on the measured deformation resistance distribution and the detected temperature distribution, the plate width direction so that the deformation resistance distribution in the strip plate width direction becomes uniform before the strip is rolled on the first rolling mill stand. It is characterized in that the control amount of the heating device required to give a temperature distribution is calculated, and the control amount of the heating device is controlled based on the calculated control amount.

Further, the cold tandem rolling method according to the fifth aspect of the present invention is
For a sample of a strip to be rolled and having a deformation resistance distribution in the plate width direction, the material distribution in the plate width direction is measured with a deformation resistance distribution measuring device that measures the material that correlates with the deformation resistance, and the material distribution is measured. A sample measurement stage in which the bearing capacity distribution in the plate width direction is measured by a tensile test at each position in the plate width direction of the sample, and
The deformation resistance distribution measuring instrument is obtained by obtaining the correlation between the material distribution in the plate width direction and the proof stress distribution in the plate width direction based on the material distribution measurement result in the plate width direction and the proof stress distribution measurement result in the plate width direction at the sample measurement stage. Calibration stage to calibrate and
During continuous tandem cold rolling of an actual strip by a cold tandem rolling mill in which a plurality of rolling mill stands are arranged in series, the strip is formed by the deformation resistance distribution measuring instrument upstream of the cold tandem rolling mill. Deformation resistance distribution measurement stage that continuously measures the material distribution in the plate width direction,
From the obtained deformation resistance distribution measurement results, the deformation resistance distribution parameter calculation stage, which calculates the parameters representing the deformation resistance distribution, and
The first regression calculation step in which the influence of the plate temperature on the deformation resistance is obtained in advance for a sample of the strip to be rolled and having a deformation resistance distribution in the plate width direction.
A heating experiment was conducted on a strip sample to be rolled in advance by a heating device for heating at least the widthwise end of the strip, and the relationship between the control amount of the heating device, the strip speed, the plate thickness, and the plate temperature was determined. The second regression calculation stage to be obtained and
Based on the relationship obtained in the first regression calculation step and the relationship obtained in the second regression calculation step, in the strip plate width direction before the strip is rolled in the first rolling mill stand. A control amount calculation step for calculating the control amount of the heating device required to give a temperature distribution in the plate width direction so that the deformation resistance distribution becomes uniform, and
It is characterized by having a temperature distribution imparting step in which the heating device is controlled by the controlled amount and the temperature distribution is imparted by the heating device so that the deformation resistance distribution in the strip plate width direction becomes uniform. ..

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, stable rolling is possible by reliably preventing the occurrence of plate breakage.

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. It is a graph which shows the relationship between the crystal grain size and the proof stress (deformation resistance) of the self-annealing coil by the experiment of the present inventors. It is a graph which shows the relationship between each position in the plate width direction and the proof stress (deformation resistance) of the self-annealed coil by the experiment of the present inventors, that is, the deformation resistance distribution in the plate width direction. It is a graph which shows the relationship between the plate temperature and the proof stress (deformation resistance) at the end portion in the plate width direction and the center portion in the plate width direction of the self-annealing coil by the experiment of the present inventors.

<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. Satisfying the relationship of 3% ≤ Al / (Si + Al) ≤ 0.5%, using a slab for non-directional electromagnetic steel plate 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 from which the surface scale has been pickled and whose surface scale has been removed is continuously subjected to the plate width in the longitudinal direction of the self-annealed strip S by the deformation resistance distribution measuring instrument 5 installed upstream of the cold tandem rolling mill 7. The deformation resistance distribution in the direction is measured. Then, based on the deformation resistance distribution measured by the deformation resistance distribution measuring device 5, the control amount for controlling the heating temperature in the heating device 6 described later (for example, when the heating device 6 is an induction heating device, the amount of current) is determined. The control amount of the heating device 6 is controlled based on the control amount calculated by the calculation device 10 and obtained by the calculation device 10.

Here, the deformation resistance distribution measuring device 5 may be a device capable of measuring the deformation resistance online in a non-destructive manner, and in practice, a measuring device for measuring a material showing a physical property value having a strong correlation with the deformation resistance is used. It may be used and the measured value of the physical property value (material) may be converted into a deformation resistance. Specifically, it is known that the crystal grain size of the steel plate correlates with the deformation resistance. Therefore, as shown in Patent Document 7, for example, the crystal grains are measured by measuring the magnetic flux distribution using a magnetic sensitive element. The diameter distribution may be obtained, and the crystal grain size distribution may be converted into a deformation resistance distribution.

That is, in the crystal particle size measuring device of the present embodiment, for example, as shown in Patent Document 7, a detection end is formed by a magnetic sensitive element fixed between a magnetizer and a magnetizer electrode, and the detection end is formed of a self-annealed strip. It may be provided on a detection head arranged so as to face the plate surface, and may have a mechanism for scanning the detection head in the plate width direction of the self-annealed strip. In the measurement, the magnetic sensitivity element detects the leakage flux generated from the grain boundaries of the crystal structure while scanning the detection head provided with the magnetically sensitive element in the plate width direction, thereby determining the crystal particle size distribution in the plate width direction. Can be measured.

In the present invention, the distribution measurement in the width direction is preferably performed in a short cycle (for example, 0.1 second), and in some cases (when scanning takes a long time), the above-mentioned detection head is self-annealed stripped. A plurality of S may be provided in the plate width direction, and the crystal grain size distribution in the plate width direction may be measured without scanning. In this case, it is preferable that the measurement position can be changed so that the crystal grains at the end of the plate at the desired position can be measured even if the plate width changes. Further, instead of scanning the entire width of the self-annealing coil with one detection head, a plurality of scanning type detection heads may be installed so that the scanning distance can be shortened so that measurement can be performed in a short cycle.

In addition to the device using the magnetically sensitive element as described above, it is also possible to measure the deformation resistance distribution by the propagation speed of ultrasonic waves, for example, as shown in Patent Document 8.

Temperature distribution in the plate width direction of the self-annealing strip S between the deformation resistance distribution measuring instrument 5 and the inlet side of the cold tandem rolling mill 7 (temperature difference between the end portion in the plate width direction and the center portion in the plate width direction). A heating device 6 is provided to generate the above-mentioned.
The heating device 6 is composed of, for example, an induction heating device that heats only the regions on both ends in the plate width direction. Specifically, as will be described later with reference to FIG. 3, a region (plate end portion) from the plate edge on both sides in the plate width direction to a position of about 10 to 15% of the plate width toward the center in the plate width direction, respectively. It is composed of an induction heating device that locally heats the region). The control amount (for example, the amount of current) of the heating device 6 is controlled by a heating control device (not shown) according to the calculation result of the calculation device 10 based on the deformation resistance distribution measured by the deformation resistance distribution measuring device 5. ing.

In this example, the heating device 6 heats only the regions on both ends in the plate width direction (plate end regions) as described above, but in some cases, the heating device 6 heats over the entire width in the plate width direction. In that case, the plate edge region may be heated non-uniformly in the plate width direction so as to be heated to a higher temperature than the region closer to the center portion in the plate width direction. Further, the heating device is not limited to the induction heating device, and for example, a steam heating type heating device, an infrared heating type heating device, a burner type heating device, an energization heating type heating device, or the like can be used.

Further, a temperature detector (not shown) may be arranged between the heating device 6 and the entrance side of the cold tandem rolling mill 7 (first stage rolling mill stand 7a), if necessary. Good. This temperature detector is for measuring the actual distribution of the temperature distribution applied in the width direction of the self-annealing strip by the heating device 6. However, in this example, it is described that the actual measurement of the temperature distribution by the above temperature detector is not performed, and in another embodiment described later, the actual measurement of the temperature distribution by the above temperature detector and the control by the actual measurement will be described.

As described above, the deformation resistance distribution in the plate width direction is continuously measured (and thus continuously along the longitudinal direction of the self-annealed strip S), and subsequently, the heating device 6 imparts a temperature distribution difference in the plate width direction. The self-annealed strip S is rolled to a thinner plate thickness by the cold tandem rolling mill 7.

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.
Here, the coolant is cooled so that the self-annealed strips are uniformly cooled in the plate width direction during rolling at each stand. Therefore, the temperature distribution difference in the plate width direction provided to the first stand entry side is maintained until the final stand entry side.

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.

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.

Here, when a strip (self-annealed strip) formed by continuous self-annealing coils by welding in a non-directional electromagnetic steel plate production line is rolled by a conventional cold tandem rolling facility according to a conventional general method. As already mentioned, the plate shape is disturbed by rolling due to the non-uniform deformation resistance in the plate width direction and the plate longitudinal direction due to the non-uniform cooling rate in the coil during the cooling process of the coil after hot finish rolling. (Usually medium-stretching), in extreme cases, plate breakage may occur.

On the other hand, in the production line of the non-directional electromagnetic steel sheet incorporating the cold tandem rolling equipment of one embodiment of the present invention as shown in FIG. 1, it is deformed upstream (entry side) of the first rolling mill stand. A resistance distribution measuring device is installed to measure the deformation resistance distribution of the self-annealing strip in the plate width direction, and based on the measurement result of the deformation resistance distribution, the self-annealing strip sent to the first rolling mill stand is in the plate width direction. By imparting a temperature difference to (controlling the temperature by feed-forward control), the non-uniformity of the deformation resistance is eliminated, and as described as an embodiment of the cold tandem rolling method described later, a large plate shape by rolling is formed. It is possible to prevent the occurrence of disorder and plate breakage.

<Knowledge on the relationship between the deformation resistance distribution of self-annealed coils and the material distribution>
In carrying out the cold tandem rolling method of the present invention, a deformation resistance distribution measuring instrument is installed upstream of the cold tandem rolling mill as described above, and the deformation resistance in the longitudinal direction and the plate width direction of the self-annealing coil. Measure the distribution. Here, as the deformation resistance distribution measuring device, a material (physical property value) having a strong correlation with the deformation resistance, for example, a measuring device for measuring the crystal grain size is used, and the measured value of the physical property value is converted into the deformation resistance to convert the deformation resistance. The distribution can be calculated. The correlation between the material distribution, especially the crystal grain size distribution and the deformation resistance distribution, has been confirmed by the following experiments by the present inventors.

That is, in the cold tandem rolling mill 7 shown in FIG. 1, a tension detector (not shown) is installed between the first stand 7a and the second stand 7b, and the plate tension between them is measured. Further, when the tension value measured by the above tension detector becomes zero while the self-annealing coil (continuous self-annealing strip) is continuously rolled by the cold tandem rolling mill 7, the first It was determined that plate breakage occurred at 1 stand 7a, and rolling was urgently stopped.
In this way, a plate sample on the entrance side of the first stand when rolling is urgently stopped due to plate breakage (hence, a sample before rolling (large plate sample) at a location close to the plate fracture location in the longitudinal direction of the plate) is collected. Further, a sample (small plate sample) at each position in the plate width direction was cut out from the large plate sample, and the material in the small plate sample was investigated. As a method for investigating the material, as the material distribution of the sample, the crystal particle size distribution in the plate width direction was investigated using the magnetic sensitive element shown in Patent Document 7.
Then, a tensile test piece was prepared from the same sample (the small plate sample), a tensile test was performed, and the proof stress at each position in the plate width direction was measured.

According to the crystal grain size distribution in the plate width direction near the plate break point in the self-annealed strip (continuous strip) investigated as described above, the crystal grains at both ends in the plate width direction are fine, whereas the plate width is fine. It was confirmed that the crystal grains in the central part of the direction were coarse. In addition, according to the results of the investigation of the proof stress at each position in the plate width direction, it was confirmed that the proof stress at the center portion in the plate width direction was lower than the proof stress at both ends in the plate width direction.

Here, in the self-annealing coil (continuously rolled self-annealed strip) investigated as described above, the grain size in the plate width direction near the plate breaking point and the crystal grain size at each position in the plate width direction at the same location. The relationship with the proof stress (deformation resistance) at each position is shown in FIG. As is clear from FIG. 2, the larger the crystal grain size, the lower the proof stress, in other words, the smaller the deformation resistance.
As already described, such a tendency is caused by the difference in the cooling rate in the plate width direction in the coil in the cooling process of the coil after hot finish rolling. That is, the cooling rate is high at both ends in the plate width direction in the coil, whereas the cooling rate is low at the center in the plate width direction.

Further, from the above-mentioned results of the investigation of the proof stress at each position in the plate width direction, the relationship between each position in the plate width direction and the proof stress (deformation resistance), in other words, the deformation resistance distribution in the plate width direction is shown in FIG. In FIG. 3, the position of the horizontal axis in the plate width direction is a standardized position, in which the central position in the plate width direction is 0 (zero) and the positions at both ends in the plate width direction are ± 1.
From FIG. 3, it is clear that the proof stress at both ends in the plate width direction is large (the deformation resistance is large).

Here, from the relationship shown in FIG. 3, the region from one end in the width direction to the central portion in the width direction from 10% to 15% of the total plate width, and the other end in the width direction toward the central portion in the width direction. The region from 10% to 15% of the total plate width (that is, the region from both ends to the position inside 10% to 15%) is defined as at least the widthwise end region to be heated, and the widthwise end thereof. It can be seen that if the partial region is softened to an appropriate degree by heating, the proof stress (deformation resistance) can be made substantially uniform over the entire width direction. For example, in the case of a self-annealing coil having a plate width of 1200 mm, if a region (width direction end region) from the width direction plate end to a position of about 120 to 180 mm is heated on both sides in the width direction, the coil is deformed over the entire width of the plate width of 1200 mm. It can be seen that the resistance can be made almost uniform.
Then, by rolling in a state where the temperature distribution is given in the plate width direction as described above, in other words, the deformation resistance distribution in the plate width direction becomes uniform, the deformation resistance distribution in the plate width direction becomes non-uniform. It is possible to prevent plate breakage during rolling due to the above.
Further, when the deformation resistance distribution shape in the plate width direction in FIG. 3 is attempted to be polynomial approximated,
It has been found that it can be approximated by a quaternary equation, in other words, the deformation resistance distribution in the plate width direction can be quantified by the approximation by the quaternary equation.

As described above, in the strip in which the plate breaks at the first stand (self-baking strip in which the self-baking coil is continuous), the crystal structure is formed at the center portion in the plate width direction and the end portion in the plate width direction near the plate break portion. However, the deformation resistance distribution in the plate width direction (bearing capacity distribution) also differs accordingly. For example, by measuring the crystal particle size distribution using a magnetic sensitive element, the deformation resistance distribution in the plate width direction (edge in the plate width direction) It was recognized that it is possible to quantify the difference in deformation resistance between the temperature of the part and the central part in the plate width direction.

<Knowledge on the effect of temperature on the deformation resistance distribution of self-annealed coils>
Furthermore, the present inventors investigated the relationship between the proof stress and the temperature of the self-annealed coil. That is, samples of the central portion in the plate width direction and the end portion in the plate width direction (a portion that is about 20% harder than the central portion of the plate) are cut out from the self-annealing coil to prepare tensile test pieces, respectively, and a warm tensile test is performed at various temperatures. Was done. The result is shown in FIG. 4 as the relationship between proof stress and temperature.
From FIG. 4, it can be seen that the change in proof stress has a linear relationship with the temperature, and the decrease (inclination) has almost nothing to do with the value (initial value) of the deformation resistance of the material.
Then, based on the result of FIG. 4, for example, the plate end portion, which is about 20% harder than the plate center portion, is heated so that the temperature is about 200 ° C. or higher than that of the plate center portion, thereby resulting in a difference in yield strength (deformation resistance difference). It turns out that can be solved. From this relationship, equation (3), which will be described later, can be regressed.

Therefore, the heating device on the entrance side of the first stand is controlled based on the deformation resistance distribution in the plate width direction to give a temperature difference (temperature distribution) in the plate width direction of the self-annealed strip rolled in the first stand. By rolling at the first stand in a state where the deformation resistance difference in the plate width direction is canceled (a state in which the deformation resistance distribution in the plate width direction becomes uniform), the occurrence of plate breakage at the first stand can be prevented. It is.

<Cold tandem rolling method>
Based on the above findings, in the basic aspect of the cold tandem rolling method of the present invention, self-rolling is performed upstream of a cold tandem rolling mill in which a plurality of rolling mill stands are arranged in series. By continuously measuring the material distribution in the plate width direction of the strip, for example, the crystal grain size distribution, the deformation resistance distribution in the longitudinal method and the plate width direction is measured, and the cold is cooled based on the measured deformation resistance distribution. A temperature difference is applied in the plate width direction of the self-yaking strip rolled at the first rolling mill stand of the inter-tandem rolling mill so that the deformation resistance distribution in the plate width direction becomes uniform (feed forward (FF) method). Control).
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 includes a sample measurement step, a calibration step, a deformation resistance distribution measurement step, a deformation resistance distribution parameter calculation step, a first regression calculation step, and a second regression calculation step. It has a regression calculation stage, a control amount calculation stage, and a temperature distribution imparting stage. Each of these steps will be described in detail below.

[Sample measurement stage]
The sample measurement step of the first embodiment is performed by a deformation resistance distribution measuring device that measures a material that correlates with the deformation resistance in advance for a sample of a strip to be rolled and has a deformation resistance distribution in the plate width direction. This is a stage in which the material distribution in the plate width direction is measured and the withstand force distribution in the plate width direction is measured by a tensile test at each position in the plate width direction of the sample.
That is, in the case of the first embodiment, a sample having a deformation resistance distribution is collected in advance, and the deformation resistance distribution measuring device is calibrated offline. Here, when the material distribution having a strong correlation with the deformation resistance distribution (for example, the particle size distribution in the embodiment of the cold rolling equipment described above) is measured as the deformation resistance distribution measuring device, the measured particle size in the plate width direction is measured. The distribution mode correlates with the deformation resistance in the same plate width direction, for example, the distribution mode of the bearing capacity, but the value of the particle size as an absolute value does not correspond to the value of the bearing capacity. Therefore, it is necessary to perform calibration for converting the measured particle size distribution into the absolute value distribution of the proof stress distribution using a sample having a deformation resistance distribution collected in advance.

Specifically, the steel type (same component) is the same as the self-annealed strip to be cold-rolled, and the heat history (heat history in the cooling process from hot rolling to finish rolling) is also the same, and the plate thickness. From a self-annealed strip having the same plate width, a sample with a deformation resistance distribution is collected (however, the sample is not limited to the sample collected from the vicinity of the fractured portion when the plate breaks at the first stand and an emergency stop occurs). Then, the particle size distribution in the width direction of the collected sample is measured, and a tensile test piece is cut out from each position in the width direction of the same sample, and a tensile test is performed along the longitudinal direction (L direction) of the sample. Measure the yield strength distribution in the width direction.

[Calibration stage]
The calibration stage is to obtain the correlation between the material distribution in the plate width direction and the proof stress distribution in the plate width direction based on the material distribution measurement result in the plate width direction and the proof stress distribution measurement result in the plate width direction in the sample measurement stage. This is the stage of calibrating the deformation resistance distribution measuring instrument. That is, based on the correspondence between the particle size and the proof stress, the particle size distribution measurement result is calibrated so that it can be converted into the proof stress distribution (deformation resistance distribution). In this way, the deformation resistance distribution can be measured as its absolute value.

[Deformation resistance distribution measurement stage]
The deformation resistance distribution measurement step is performed during continuous tandem cold rolling of an actual strip by a cold tandem rolling mill in which a plurality of rolling mill stands are arranged in series, and the deformation resistance is said to be upstream of the cold tandem rolling mill. This is the stage of measuring the material distribution of the strip in the plate width direction with a distribution measuring instrument.
That is, the material distribution (for example, particle size distribution) in the plate width direction of the strip fed to the cold tandem rolling mill is measured upstream of the cold tandem rolling mill using the deformation resistance distribution measuring device calibrated by the calibration step. Then, the distribution is output as the deformation resistance distribution measurement result.

[Deformation resistance distribution parameter calculation stage]
The deformation resistance distribution parameter calculation step is a step of calculating a parameter representing the deformation resistance distribution by polynomial approximation of the deformation resistance distribution measurement result obtained by the deformation resistance distribution measurement step.
Specifically, the deformation resistance distribution obtained through the calibration step, for example, the relationship between the position in the plate width direction (horizontal axis x) and the proof stress (deformation resistance: vertical axis y) as shown in FIG. 3 is polynomial. Approximation, for example, the quaternary equation shown in the following equation (1) is used for approximation.
y = ax ⁴ + b ... (1)
Here, the position x in the plate width direction is standardized with the positions at both ends in the plate width direction being ± 1 and the center position in the plate width direction being 0.
Then, from the quaternary equation ((1) equation), how much the proof stress (a + b) at the plate edge is larger than the proof stress (b) at the center of the plate as the deformation resistance distribution parameter α (how large the deformation resistance is). The parameter α representing (?) Is calculated by the following equation (2).
α = (a + b) -b
= A ・ ・ ・ (2)

[First regression calculation stage]
The first regression calculation step is a step in which the influence of the plate temperature on the deformation resistance is obtained in advance for a sample of the strip to be rolled and having a deformation resistance distribution in the plate width direction.
Specifically, a sample in the plate width direction is cut out from a self-annealed strip having a deformation resistance distribution, and the effect of temperature on the proof stress is investigated by a warm tensile test, and the change in deformation resistance (Δσ) and the deformation resistance (σ) are investigated. ), The relationship with the temperature rise (ΔT) from the plate temperature (room temperature, for example, 20 ° C.) at the time of non-heating on the entrance side of the first rolling mill stand is returned by the following equation (3).
Δσ = f (ΔT) ・ ・ ・ (3)

[Second regression calculation stage]
In the second regression calculation step, a heating experiment is performed on a sample of the strip to be rolled in advance by a heating device for heating at least the widthwise end of the strip, and the control amount, strip speed and plate of the heating device are performed. This is the stage to find the relationship between the thickness and the plate temperature.
Specifically, a heating experiment was conducted on a strip sample to be rolled in advance using the heating device, and a heating control amount (β), a strip speed (V), a plate thickness (H), and a plate temperature (T) were performed. The relationship between the plate temperature (T) after heating, the strip speed (V), the plate thickness (H), the heating control amount (β), and the control amount is regressed by the following equation (4). Keep it.
T = g (V, H, β) ... (4)

[Control amount calculation stage]
The controlled variable calculation step is based on the relationship obtained in the first regression calculation step and the relationship obtained in the second regression calculation step before the strip is rolled on the first rolling mill stand. This is a step of calculating the control amount of the heating device required to give a temperature distribution in the plate width direction so that the deformation resistance distribution in the strip plate width direction becomes uniform.
That is, a strip that is not heated by the heating device and has no deformation resistance distribution in the plate width direction (the deformation resistance at the plate end of this strip is σ ₁ ) is rolled at the first rolling mill stand at a _{rolling speed V 1.} When a strip having a deformation resistance distribution in the plate width direction (the deformation resistance at the plate end of this strip is σ ₂ ) arrives at the first rolling mill stand, it is rolled by the first rolling mill stand. The deformation resistance at the end of the strip changes from σ _{1 to σ 2.}

Here, in the method of the present invention, the deformation resistance distribution of the strip in the plate width direction is measured upstream of the rolling mill, and the parameters of the deformation resistance distribution (deformation resistance at the plate end and deformation resistance at the center of the plate). If (corresponding to the difference) is α, a strip having a deformation resistance distribution in the plate width direction has arrived at the first rolling mill stand from a state in which a strip having no deformation resistance distribution is rolled at the first rolling mill stand. Occasionally, the deformation resistance distribution parameter α _{changes from α 1} (basically zero) to α ₂ (corresponding to the amount of change in deformation resistance). That is, the deformation resistance changes by _{α 2.}

Further, from the equation (4), the temperature change (ΔT) of the strip when the _{heating control amount (β) is changed from β 1} to β _{2 is obtained by the following equation (5).}
ΔT = g (V ₂ , H ₂ , β ₂ ) -g (V ₁ , H ₁ , β ₁ ) ... (5)
Here, in the self-annealing coil, the plate thickness H is uniform in the longitudinal direction, and V does not change at a constant rolling speed. In that case, ΔT can be obtained by the following equation (5'). ..
ΔT = g (V ₁ , H ₁ , β ₂ ) -g (V ₁ , H ₁ , β ₁ ) ... (5')

Further, from the equations (3), (4) and (5) or (5'), the relationship of the following equation (6) can be obtained.
Δσ = f (ΔT) ・ ・ ・ (6)
Therefore, by solving these relational expressions, the heating rise temperature of the plate end required so that the deformation resistance distribution is uniform (that is, the deformation resistance of the plate end is the same as that of the plate center), that is, heating _{The heating control amount (β 2} ) at the plate end of the apparatus can be obtained.

[Temperature distribution setting stage]
The temperature distribution imparting step is a step in which the heating device is controlled by the controlled amount (for example, the current amount of the heating device), and the heating device imparts a temperature distribution so that the deformation resistance distribution in the strip plate width direction becomes uniform. Is. That is, it is a stage in which the heating device is controlled by a heating control device (not shown) with _{the obtained control amount of β 2.}

As described above, the temperature distribution of the strip rolled at the first stand is controlled by the FF method according to the change in the deformation resistance distribution (heating control is performed so that the deformation resistance distribution in the strip plate width direction becomes uniform). As a result, even if a portion of the self-annealed strip having a large non-uniform deformation resistance distribution in the plate width direction is suddenly fed to the stand, the shape after rolling does not change, and therefore, due to drawing or the like due to the shape change. It is possible to prevent the occurrence of plate breakage.

In the embodiment of the rolling method described above, the heating device is controlled by the feedforward method (FF method) according to the measured change in the deformation resistance distribution, but as described above. When a temperature detector for measuring the temperature distribution of the strip is placed between the heating device and the entrance side of the first rolling mill stand, the FF method is used according to the change in the measured deformation resistance distribution. At the same time as controlling the heating device, the heating device may be controlled by a feedback method (FB method) according to the actually measured temperature distribution. This means that the FF method and the FB method are used in combination to control the temperature distribution in the plate width direction so that the deformation resistance distribution in the strip plate width direction becomes uniform. By doing so, the deformation resistance distribution in the strip plate width direction becomes uniform more reliably, and the occurrence of plate breakage can be prevented even more reliably.
Further, the above has been described with the case where the deformation resistance distribution in the plate width direction is symmetrical, but it goes without saying that the case where the deformation resistance distribution in the plate width direction is asymmetric can be handled in the same manner.
That is, the deformation resistance distribution in the plate width direction is approximated by a quaternary equation, and the parameter on one plate end side is α ₁ and the parameter on the other plate end side is α ₂ , and the deformation resistance distribution in the strip plate width direction is uniform. The temperatures ΔT ₁ and ΔT ₂ to be obtained may be obtained by the above-mentioned procedure, and the heating of both ends in the plate width direction may be controlled.

Hereinafter, examples and comparative examples relating to the cold tandem rolling method of each embodiment of the present invention will be described.
Both Examples and Comparative Examples were carried out in a cold tandem rolling mill 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 Examples and Comparative Examples 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): Using a slab for non-directional electromagnetic steel sheet that satisfies the relationship of 0.4% and contains the balance Fe and unavoidable impurities, hot finish rolling is performed so that the hot finish rolling temperature becomes 1090 ° C. After that, the non-injection time was set to 6 seconds, and the rolling was performed 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 a deformation resistance distribution measuring device, a crystal particle size measuring device using a magnetic sensitive element as described above is installed on the entrance side of the first rolling mill stand, and the particle size distribution measured on the entrance side of the first rolling mill stand. Was applied to the method of converting to the bearing capacity distribution (deformation resistance distribution). Further, as a heating device, an induction heating type heating device as described above was installed between the deformation resistance distribution measuring device and the entrance side of the first rolling mill stand. In addition, this heating device was configured to locally heat a region (end region) from both ends in the plate width direction to a position of 150 mm toward the central portion.

The modes of measurement and control in Examples and Comparative Examples are as follows.
-Comparative example: This is an example corresponding to a conventional general rolling method, and even if there is a deformation resistance distribution in the plate width direction, the self-annealed strip is rolled without controlling the heating device.
Example: The deformation resistance distribution of the self-annealed strip in the plate width direction is measured, and the control amount (current amount) of the heating device on the entrance side of the first rolling mill stand is adjusted according to the value of the above-mentioned deformation resistance distribution parameter α. FF control was performed.

As described above, the self-annealed strips were rolled for 100 coils each according to Examples and Comparative Examples. In each example, the occurrence of plate breakage at the first rolling mill stand was investigated. The deformation resistance distribution parameter α includes those that vary in the range of 0 to 110 MPa (the ratio of the proof stress at the end of the plate to the proof stress at the center of the plate is 1 to 1.2). However, the variation (size, position) of α for each coil is large, and it is not always 100 coils under the same conditions. In the case of the example, the temperature at the end of the plate was controlled to be higher than the temperature at the center of the plate in the range of 0 to 200 ° C.

As a result of the investigation as described above, in the comparative example, when the parameter α was 55 MPa or more (the ratio of the proof stress at the end of the plate to the proof stress at the center of the plate was 1.10 or more), the plate fracture occurred with a probability of about 90%. On the other hand, in the case of the example, no plate breakage was observed even when the parameter α was 55 MPa or more (the ratio of the proof stress at the end of the plate to the proof stress at the center of the plate was 1.10 or more).

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.

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 Deformation resistance distribution measuring device 6 Heating device 7 Cold tandem rolling mill 7a, 7b, 7c, 7d, 7e Cold tandem Rolling machine stand 8 Cutting machine 9 Carrosel reel 10 Computing device

Claims (5)

Strips upstream of a cold tandem rolling mill consisting of multiple rolling mill stands arranged in series by continuously measuring the distribution in the strip width direction for materials that correlate with the deformation resistance of the strip to be rolled. A deformation resistance distribution measuring device for measuring the deformation resistance distribution in the longitudinal method and the width direction of the strip plate is provided.
Further, based on the measured deformation resistance distribution, the temperature distribution is distributed in the strip plate width direction between the deformation resistance distribution measuring device and the first rolling mill stand located on the most upstream side of the plurality of rolling mill stands. A heating device to generate and
Calculation for calculating the control amount of the heating device required to obtain the temperature distribution in the plate width direction so that the deformation resistance distribution in the strip plate width direction becomes uniform based on the measured value of the deformation resistance distribution measuring device. With the device
A cold tandem rolling facility including a heating control device that controls a control amount of the heating device based on a calculated control amount. In the cold tandem rolling equipment according to claim 1.
A cold tandem rolling facility characterized in that a temperature detector for measuring the temperature distribution of the strip in the plate width direction is provided between the heating device and the first rolling mill stand. Strips by continuously measuring the distribution in the strip width direction for materials that correlate with the deformation resistance of the strips being rolled upstream of a cold tandem rolling mill consisting of multiple rolling mill stands arranged in series. Measure the deformation resistance distribution in the longitudinal method and strip plate width direction,
Further, before the strip whose deformation resistance distribution has been measured is rolled by the first rolling mill stand located on the most upstream side of the plurality of rolling mill stands, the strip is at least at the end in the plate width direction by a heating device. The rolling mill is heated to generate a temperature distribution in the plate width direction.
Moreover, based on the measured deformation resistance distribution, the control amount of the heating device required to obtain the temperature distribution in the plate width direction so that the deformation resistance distribution in the strip plate width direction becomes uniform was calculated and calculated. A cold tandem rolling method characterized in that the controlled amount of the heating device is controlled based on the controlled amount. Strips by continuously measuring the distribution in the strip width direction for materials that correlate with the deformation resistance of the strips being rolled upstream of a cold tandem rolling mill consisting of multiple rolling mill stands arranged in series. Measure the deformation resistance distribution in the longitudinal method and strip plate width direction,
Further, the strip whose deformation resistance distribution has been measured is at least end in the plate width direction by a heating device before being rolled by the first rolling mill stand located on the most upstream side of the plurality of rolling mill stands. The region is heated to generate a temperature distribution in the strip width direction, and the temperature distribution in the strip width direction is measured between the heating device and the entrance side of the first rolling mill stand.
Based on the measured deformation resistance distribution and the detected temperature distribution, the plate width direction so that the deformation resistance distribution in the strip plate width direction becomes uniform before the strip is rolled on the first rolling mill stand. A cold tandem rolling method comprising calculating a controlled amount of the heating device required to give a temperature distribution and controlling the controlled amount of the heating device based on the calculated controlled amount. For a sample of a strip to be rolled and having a deformation resistance distribution in the plate width direction, the material distribution in the plate width direction is measured with a deformation resistance distribution measuring device that measures the material that correlates with the deformation resistance, and the material distribution is measured. A sample measurement stage in which the bearing capacity distribution in the plate width direction is measured by a tensile test at each position in the plate width direction of the sample, and
The deformation resistance distribution measuring instrument is obtained by obtaining the correlation between the material distribution in the plate width direction and the proof stress distribution in the plate width direction based on the material distribution measurement result in the plate width direction and the proof stress distribution measurement result in the plate width direction at the sample measurement stage. Calibration stage to calibrate and
During continuous tandem cold rolling of an actual strip by a cold tandem rolling mill in which a plurality of rolling mill stands are arranged in series, the strip is formed by the deformation resistance distribution measuring instrument upstream of the cold tandem rolling mill. Deformation resistance distribution measurement stage that continuously measures the material distribution in the plate width direction,
From the obtained deformation resistance distribution measurement results, the deformation resistance distribution parameter calculation stage, which calculates the parameters representing the deformation resistance distribution, and
The first regression calculation step in which the influence of the plate temperature on the deformation resistance is obtained in advance for a sample of the strip to be rolled and having a deformation resistance distribution in the plate width direction.
A heating experiment was conducted on a sample of strip to be rolled in advance by a heating device for heating at least the widthwise end of the strip, and the relationship between the controlled amount of the heating device, the strip speed, the plate thickness, and the plate temperature was determined. The second regression calculation stage to be obtained and
Based on the relationship obtained in the first regression calculation step and the relationship obtained in the second regression calculation step, in the strip plate width direction before the strip is rolled in the first rolling mill stand. A control amount calculation step for calculating the control amount of the heating device required to give a temperature distribution in the plate width direction so that the deformation resistance distribution becomes uniform, and
A cold tandem characterized by having a temperature distribution imparting step in which the heating apparatus is controlled by the controlled amount and the temperature distribution is imparted by the heating apparatus so that the deformation resistance distribution in the strip plate width direction becomes uniform. Rolling method.

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