JP2010005682A - Cooling control method of hot-rolled metal strip using near-infrared camera in hot rolling and method for manufacturing of hot-rolled metal strip - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for adequately carrying out quality assurance for delivering a product to a user, and also to provide a method for manufacturing of a hot-rolled metal strip using the same. <P>SOLUTION: A cooling-related equipment 26 between a finish-rolling mill 18 of a hot rolling line 100 and a coiler 24 is divided into a first half zone 5 and a second half zone 4. In the first half zone 5, cooling water is supplied, whose water amount density per one surface of a front surface and a rear surface is ≥0.7 m<SP>3</SP>/m<SP>2</SP>/min and ≤1.2 m<SP>3</SP>/m<SP>2</SP>/min respectively. In the second half zone 4, cooling water is supplied, whose water amount density per one surface of the front surface and the rear surface is ≥0.0 5m<SP>3</SP>/m<SP>2</SP>/min and ≤0.3 m<SP>3</SP>/m<SP>2</SP>/min respectively. In this way, the temperature of the hot-rolled metal strip 8 immediately before winding is controlled. In the first half zone 5, in addition thereto, the full width of hot-rolled metal strip 8 installed at the exit side of the first half zone 5 is fed back to the control of the temperature of the hot-rolled metal strip 8 in the first half zone 5 based on result of temperature measurement by a near-infrared camera 27A capable of photographing a full length or a part of the full length so that the temperature of the hot-rolled metal strip 8 immediately before winding is controlled. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

In the present invention, when a metal material is hot-rolled to form a hot-rolled metal strip (hereinafter referred to as a material to be rolled), before taking up as the hot-rolled metal strip, the near-infrared camera is used to The present invention relates to a method for controlling the cooling of a hot-rolled metal strip, which controls the cooling of the hot-rolled metal strip based on the measurement results, and a method for manufacturing a hot-rolled metal strip using the same. .

The hot rolling is generally performed by heating a slab-like metal material produced by continuous casting, ingot-making, or ingoting to several hundred to several hundreds of degrees Celsius in a heating furnace, and then on the hot rolling line. This is a process in which the roll is rotated while being pinched by a pair or a plurality of pairs of rolls, and is rolled thinly and wound into a coil shape.

  FIG. 31 shows an example of a hot rolling line 100 generally used conventionally. A metal material 140 to 300 mm thick (hereinafter referred to as a material to be rolled. After finish rolling is also referred to as a hot-rolled metal strip) 8 heated to several hundred to several hundreds of degrees Celsius by the heating furnace 10 is a rough rolling machine 12 and finish. It is rolled to a thickness of 0.8 to 25 mm by a rolling mill 18 and thinly extended into a metal strip shape.

  In the case of the hot rolling line 100 shown in FIG. 31, the rough rolling mill 12 has two groups of R2 and R4, but the number of bases is not necessarily limited thereto. In addition to one or two, the most common one is four, and the one with a large number is up to six. As in the case of the hot rolling line 100 shown in FIG. 31, the numbers R2 and R4 are skipped only because R1 and R3 are planned to be added to empty spaces in the future when production increases. . Although not shown in FIG. 31, there is also one in which a width press is installed immediately upstream of the roughing mill 12.

  In the case of the hot rolling line 100 shown in FIG. 31, the number of rolling mills (stands) constituting the finish rolling mill 18 is seven in F1 to F7, but there are six.

  Although there are differences in these various radixes, the roughing mill 12 generally performs rough rolling 6 times or 7 times in total by reciprocating rolling, unidirectional rolling, or both, and the material to be rolled after rough rolling. 8 is supplied to the finishing mill 18 following it. Each rolling in the rough rolling is also called a rolling pass, and rolling a plurality of times such as 6 times or 7 times is also called rolling with 6 passes or 7 passes.

In the case of the hot rolling line 100 shown in FIG. 31, rough rolling is performed with a total of 6 passes, 5 passes for R2 and 1 pass for R4. (In the case of the four most common ones, it is common to perform rough rolling in a total of 6 passes, 3 passes for R1, 1 pass each for R2, R3, and R4.)
The finishing mill 18 takes the form of a tandem rolling mill that simultaneously rolls a high-temperature workpiece 8 of several hundred to several hundreds of degrees Celsius with a plurality of rolling mills, but is not a finishing tandem rolling mill and is simply “finishing”. Often referred to as a “rolling mill”. 19 is a roll.

  As shown in FIG. 31, it is a hot rolling method in which one rolling material is rolled by the finish rolling mill 18 and the next rolling material is rolled at a time interval for a while to repeat the operation. Is called batch rolling. On the other hand, in some cases, the materials to be rolled are joined and finish-rolled, which is called continuous hot rolling or endless rolling, but batch rolling is more common.

  By the way, in the hot rolling line 100, many (one hundred or more) table rolls (not shown) are installed between other rolling mills (stands) except between the stands of the finish rolling mill 18. The rolled material 8 is conveyed.

  Further, when the material 8 is extracted from the heating furnace 10, oxide layers (hereinafter referred to as scales) are formed on the front and back surfaces thereof. In addition, since the rolled material 8 is exposed to the atmosphere at a high temperature even in the process of being rolled and thinned and lowered in temperature by heat radiation, new scales are generated on the front and back surfaces of the rolled material 8. For this reason, on the entry side of each rolling mill in the rough rolling mill 12, descaling is performed by spraying high-pressure water inside and outside 10 to 30 MPa on the front and back surfaces of the material to be rolled 8 as the supply pressure from the pump. A device 16 is installed to remove the scale.

  Moreover, although not shown in figure, since each work roll 19 contacts a hot material to be rolled, it is cooled with cooling water. Each backup roll 20 is also cooled by cooling water.

  In FIG. 31, reference numeral 14 denotes a crop shear, which cuts and removes the crop at the leading end of the material 8 to be rolled (finished portion of the leading end of the material 8 to be distorted) before finish rolling. 18 is shaped into a substantially rectangular planar shape that is easy to be smoothly bitten.

  50 is a control device, 70 is a process computer, and 90 is a business computer.

  Incidentally, the quality required for the metal strip rolled in the hot rolling line 100 as shown in FIG. 31 has become increasingly sophisticated in recent years. A typical example is a steel product, that is, a steel strip. In particular, with the recent trend toward lighter automobiles, the demand for high-tensile steel, that is, high-tensile steel, has increased, and the required quality has also improved.

  In other words, high-tensile steel often refers to those having a tensile strength of 400 MPa or more, but in recent years, not only high tensile strength, but also does not crack when subjected to press working or hole expansion processing, In addition to high workability such as, it is also required that the quality such as tensile strength and high workability should be as uniform as possible on the steel strip that is the product. Quality is becoming more sophisticated.

  In the production of high-strength steel, in terms of composition, the Si content is typically increased, but in addition, depending on the use of the steel strip and the quality required for it, C, Mn, Ti, Nb, ... Various adjustments may be made.

  However, whatever the components, the manufacturing technology and conditions for creating the above-mentioned quality at the hot rolling manufacturing stage are particularly important, and among them, the rolled material after finish rolling The temperature of the material 8 is cooled to a temperature of 0 ° C. and wound by the coiler 24, and how the temperature just before winding is made as uniform as possible on the steel strip as a product. It becomes a challenge.

  Therefore, in the example of the hot rolling line 100 shown in FIG. 31, the temperature immediately before winding of the material to be rolled 8 measured by the coiler entry side thermometer 25 is the product hot rolled metal strip delivered to the customer. In addition, it is most important for quality assurance, and in addition, control of the run-out table 23 and the cooling-related equipment 26 installed therein is important. Furthermore, the temperature of the material 8 to be rolled immediately after finish rolling, which is measured with the finish delivery thermometer 21, is also important.

  As mentioned earlier, in recent years, the quality required for high-strength steel has become sophisticated, and on the steel strip that is the product, how the quality can be made as uniform as possible. In addition, how to make the temperature just before winding as uniform as possible has become a problem. For that purpose, the temperature just before winding the material to be rolled 8 is changed to the material to be rolled 8. Must be measured over the full width of In addition, when considering the control of the runout table 23 and the cooling-related equipment 26 installed thereabove, the temperature immediately after finish rolling of the material 8 to be rolled must also be measured over the entire width of the material 8 to be rolled. There is also.

  In this regard, in the past, in a hot rolling line such as the hot rolling line 100 that has been generally used conventionally, the finishing side thermometer 21 and the coiler inlet side thermometer 25 have a width of the material 8 to be rolled. It is fixedly installed at a position corresponding to the center of the direction (coinciding with the center of the width of the hot rolling line under the condition that the material to be rolled 8 does not meander at all), and the diameter of the visual field spot is 20 to 50 mm at most. Relied on a radiation thermometer.

  That is, this is a method in which the temperature is measured over the entire length, with the center in the width direction of the rolled material 8 as a representative, and the temperature distribution in the width direction is not measured. In the old days, this was sufficient for quality assurance of the hot-rolled metal strips delivered to customers.

  However, even if the result of the temperature measurement over the entire length, represented by the center in the width direction of the material 8 to be rolled, is a temperature distribution that is acceptable for quality assurance in the longitudinal direction of the material 8 to be rolled, Even in the width direction of 8, the temperature distribution that is acceptable for quality assurance cannot be actually guaranteed unless the width direction temperature distribution is measured.

  Under batch rolling, the effect of flatness control in the finish rolling mill 18 does not yet appear. The tip of the material 8 to be rolled is several tens of meters, or the tension does not act, and the coiler 24 starts from the final stand of the finishing mill 18. In the hundreds of tens of meters of the tip or tail end of the material to be rolled 8 corresponding to the distance up to, there is inevitably an uneven portion of the shape of the material to be rolled 8, and the shape of the mountain wave is irregular, As shown in FIG. 32, when a pool of cooling water is locally generated at the tip of the material 8 to be rolled, the portion is strongly cooled locally and the temperature distribution in the width direction becomes uniform. Hateful.

  By the way, the phenomenon that occurs between the surface of the steel and the cooling water is that when the temperature of the steel material to be rolled is 550 ° C. or higher, the entire surface of the material to be rolled 8 is a water vapor film as shown in FIG. Although it is in a state of film boiling covered with 550 ° C., the film of water vapor becomes unstable from below about 550 ° C., and there is a part where the cooling water w and the material to be rolled 8 are in direct contact with each other. As shown in FIG. 33 (b), when the state of nucleate boiling is reached and the temperature of the material to be rolled 8 is lowered as a whole, the state of nucleate boiling is entirely transferred.

  The problem is that in the process in which the temperature of the material to be rolled 8 is decreasing as a whole, nucleate boiling promotes heat transfer rather than film boiling, and the value converted to a heat transfer coefficient also increases. In the part where nucleate boiling occurs, the temperature of the material to be rolled 8 is likely to decrease locally compared to other surrounding parts.

  In the case of high-strength steel, the value obtained as the temperature immediately before winding is often less than 550 ° C. in order to ensure quality, and therefore the timing of passing through the temperature range where film boiling shifts to nucleate boiling is the material to be rolled 8 There is an early part and a late part in some parts and other parts around.

  In the portion having the water pool as described above, a portion having a low temperature (black spot) is locally formed on the material 8 to be rolled, so that the material 8 to be rolled immediately before winding is finally formed between the portion having the water pool and the portion not having the water pool. Accordingly, the quality of the rolled material 8 as a whole is not uniform, and the quality is locally deviated from the allowable range.

In Patent Document 1, the total length and the water density of 0.3 m ³ / m ² / min or more and 1.0 m ³ / m ² / min or less were common in the cooling zone before that, as shown in FIG. The cooling zone is divided into the first half zone and the second half zone, and the slit laminar method with water density of 1.0m ³ / m ² / min to 5.0m ³ / m ² / min in the first half zone. Strong cooling is performed at 550 ° C. (C position in FIG. 34) with a pipe laminar system with a water density of 0.3 m ³ / m ² / min to 1.0 m ³ / m ² / min. Then, while suppressing the growth of crystal grains, in the latter half zone, slowly cool to 450 ° C. by a spray method with a water density of 0.05 m ³ / m ² / min or more and less than 0.3 m ³ / m ² / min. And proposes to make the temperature just before winding as uniform as possible.

  Incidentally, in FIG. 34, 5 is the first half zone in which equipment for strong cooling (slit laminar system) is arranged, 4 is the latter half zone in which equipment for slow cooling (spray system) is arranged, and 3 is the total length of the cooling zone. 34 (b) is an enlarged view of the portion B in FIG. 34 (a). In FIG. 34 (b), 31, 41 and 51 are header pipes, and 32 is a pipe laminator. A nozzle 42 is a spray nozzle, and 52 is a slit laminar nozzle.

Patent Document 1 focuses on the fact that the transition temperature that changes from a film boiling region with a slow cooling rate to a nucleate boiling region with a fast cooling rate decreases when the water density decreases, and in the latter half zone, 0.05 m ³ / By performing slow cooling at a low water density of m ² / min or more and less than 0.3 m ³ / m ² / min, the temperature immediately before winding is made as uniform as possible.

  In addition, efforts to measure the temperature distribution in the width direction of the material to be rolled 8 have been made before. However, there are problems as described above, and it can be said that their importance has increased in recent years.

  In the past, in order to measure the temperature distribution in the width direction of the material 8 to be rolled, in addition to the thermometer fixedly installed at a position corresponding to the center in the width direction of the material 8 to be rolled, By installing a thermometer that scans in the width direction, and scanning the material 8 being conveyed in the width direction, the result is a scan (scanning) that draws a locus on the material 8 as a result. ) And measured the temperature. For this reason, as shown in FIG. 35 as seen from above the hot rolling line, the portion called a black spot having a locally low temperature may not be scanned, and as a result, the portion may not be detected.

  Patent Document 2 describes that the temperature distribution in the width direction of the steel sheet after controlled cooling is discretely measured over the entire length of the steel sheet. As shown in FIG. 36, black or shadow in which the timing when the temperature deviation occurs in the width or longitudinal direction of the steel sheet coincides with the timing of starting or ending the use of cooling-related equipment such as cooling banks, nozzles and / or headers. It is described that a part of the entire length of the entire length 8 of the material to be rolled 8 is determined as an abnormal part, and the cooling device is also diagnosed as abnormal.

  In Patent Document 2, as can be seen from FIG. 36, the temperature of the material to be rolled 8 is measured discretely at a pitch of 200 mm in the width direction, as can be seen.

  In patent document 3, in the case of a thick plate rolling line, the temperature distribution of the steel sheet is measured by a thermoviewer or a scanning (scanning) type radiation thermometer on the downstream side (exit side) of the hot straightening device (hot leveler). The purpose is to determine the residual stress distribution, and to adjust the conditions of the heat treatment that is the subsequent manufacturing process, thereby suppressing the deformation due to residual stress release when cutting the steel sheet as much as possible, That's it.

  Here, the thermoviewer means that the basic principle is the same as that of a near-infrared camera. For example, square pixels are arranged two-dimensionally vertically and horizontally, and temperature data measured at each pixel is linearly interpolated to obtain the temperature of the object. The distribution is to be measured pseudo-continuously, but the vertical and horizontal dimensions per pixel are smaller than 200 mm, which is an example of the discrete temperature measurement pitch in Patent Document 2 described above. For this reason, a temperature distribution closer to continuity can be measured.

  In Patent Document 3, it is unclear where and how much region of the material to be rolled is to be measured, but it is certain that the temperature is not full. As an example, there is a reference to a steel plate with a width of 3000 mm, but as a measurable region, a near infrared camera capable of covering the entire width of a steel plate with a width of 3000 mm has been developed as well as at the time of filing of Patent Document 3. Because it is not.

  Patent Document 4 describes that the temperature of the plane of the steel plate being transported is measured on the upstream side (incoming side) of the cooling-related equipment for the case of a hot rolling line of a steel strip. The purpose is to perform cooling control by water cooling when the minimum temperature of the plane temperature is not more than a predetermined temperature and the deviation of the plane temperature is not more than a predetermined value, and the deviation of the plane temperature is a predetermined value. When the temperature exceeds the range, by performing cooling control by gas cooling, the temperature deviation is reduced and the quality is made as uniform as possible.

  In Patent Document 4, a near infrared camera is not described as a means for measuring the temperature of the plane of the steel sheet, and it is also unclear where and how much of the rolled material is to be measured. It is.

Finally, Patent Document 5 is cited here because it is cited in the best mode for carrying out the invention described later.
Japanese Patent No. 3817153 JP-A-2005-279665 JP 2003-31326 A JP 2000-313920 A JP 2007-203369 A

  Although the technique of Patent Document 1 aims to make the temperature immediately before winding as uniform as possible, the planar (two-dimensional) temperature distribution of the material to be rolled immediately before winding results in Until now, it is not a measurement target, and of course, the measurement result is not recorded, and further, the cooling method is not controlled based on the measurement result. For this reason, the subject remained in the point that the quality assurance in the product delivery with respect to a consumer is not enough.

  Since the technique of Patent Document 2 is based on discrete temperature measurement of a material to be rolled, such as a 200 mm pitch in the width direction, the material to be rolled being transported has been scanned in the width direction, which has been performed for a long time. As in the case of measuring the temperature, there is a problem that a portion called a black spot having a locally low temperature may not be detected.

  The technique of Patent Document 3 is intended for thick plate rolling lines, and the measurement field of view does not cover the full width of the material to be rolled. For this reason, when there is a portion called a black spot having a locally low temperature in a portion of the material to be rolled out of the field of view, there is a problem that the same portion may not be detected in the same manner.

  The technique of Patent Document 4 also has a problem that the shutter speed described in the best mode for carrying out the invention to be described later is not sufficiently short according to the technical level at the time of filing. It is unlikely to cover the full width, and only describes that the cooling by the cooling-related equipment is used for control to switch between water cooling and air cooling in a feed-forward manner. As a result, the flat (two-dimensional) temperature distribution of the material to be rolled is not subject to measurement, and the measurement results are not recorded, and products for consumers are not used. The problem remained in that we could not guarantee the quality on delivery.

  The present invention has been made to solve such a problem of the prior art, and the measurement result is the result of the planar (two-dimensional) temperature distribution of the material to be rolled before winding. In addition, by providing a cooling control method for hot-rolled metal strips using a near-infrared camera that controls the cooling method, it is possible to properly guarantee the quality of products delivered to consumers. An object of the present invention is to provide a method for producing a hot-rolled metal strip.

That is, the present invention is as follows.
(1) The cooling-related equipment between the finishing mill of the hot rolling line and the coiler is divided into two zones, a first half zone and a second half zone. In the first half zone, the water volume density per front and back single side is 0.7 m ³ / m ² / min. Cooling water of 1.2 m ³ / m ² / min or less is supplied, and in the latter half zone, the water density is 0.05 m ³ / m ² / min or more and 0.3 m ³ / m ² / min or less per front and back side surfaces. Supplying water to control the temperature of the hot-rolled metal strip immediately before winding, and in addition to that, in the first half zone, the full width of the hot-rolled metal strip installed on the outlet side of the first half zone, Based on the result of temperature measurement with a near-infrared camera, which can be photographed for the entire length or a part of the total length, it is fed back to the control of the temperature of the hot-rolled metal strip in the first half zone Previous, previous A method for controlling the cooling of a hot-rolled metal strip, comprising controlling the temperature of the hot-rolled metal strip.
(2) In order to compensate for the temperature rise immediately before winding of the hot-rolled metal strip due to the feedback of (1), feed-forward is performed to control the temperature of the hot-rolled metal strip in the latter half zone, and winding is performed. The method for controlling cooling of a hot-rolled metal strip according to (1), wherein the temperature of the hot-rolled metal strip immediately before is controlled.
(3) When the method for controlling cooling of a hot-rolled metal strip in (1) above is applied to a hot-rolled metal strip, and the next hot-rolled metal strip has the same material and dimensions, Based on the temperature measurement result in one image of the metal band taken in the field of view of the near infrared camera, the average temperature of the hot-rolled metal band and the minimum temperature in the one image from the average temperature The deviation obtained by subtracting the value is calculated, and by the feedback, the deviation is less than the threshold ΔTL for determining that the temperature of the hot-rolled metal strip becomes uneven in the width direction in the hot-rolled metal strip. The average value in the longitudinal direction of the measurement result of the temperature at the center of the width of the hot rolling line on the exit side of the first half zone of the hot-rolled metal strip after the time point, As described above, the temperature at the center of the width of the hot rolling line at the exit side of the first half zone As a standard value, the above-mentioned, cooling control method for the hot-rolled metal strip, characterized in that to perform the cooling control for the next hot rolled metal strip.
(4) A method for producing a hot-rolled metal strip using any one of (1) to (3).

  According to the present invention, the near-infrared camera that controls the cooling method based on the measurement result of the result of the planar (two-dimensional) temperature distribution of the rolled material before winding is used. By providing the cooling control method for the hot-rolled metal strip, it is possible to provide a method for appropriately performing quality assurance for product delivery to the customer and a method for manufacturing the hot-rolled metal strip using the method.

(Primary cooling control method for hot-rolled metal strip)
A method for controlling the cooling of a hot-rolled metal strip according to an embodiment for carrying out the present invention will be described below.

  The inventors flatten and eliminate such non-uniformity later when a part of the material to be rolled (hot-rolled metal strip) after finish rolling comes to the beginning of nucleate boiling. In view of the fact that it remains as a non-uniform temperature just before winding, which leads to non-uniform material quality of the product hot-rolled metal strip, the present invention has been made.

  Control of the temperature of the hot-rolled metal strip immediately before winding is performed as originally described in outline as follows.

  When the material 8 to be rolled roughly rolled by the roughing mill 12 shown in FIG. 31 has been transported to just below the finishing input thermometer 15 and its tip reaches directly below the finishing input thermometer 15, The temperature of the tip of the material 8 to be rolled is transmitted from the finish entry thermometer 15 to the process computer 70.

  In the process computer 70, it is determined whether or not the temperature of the tip of the material 8 to be rolled is equal to or higher than a certain threshold, for example, 700 ° C. or higher. In this case, it is determined that the tip of the material to be rolled 8 has reached directly below the finishing entry thermometer 15.

  Then, in the process computer 70, a target signal is obtained from a business computer 90 higher than the process computer 70 with a trigger signal that it is determined that the tip of the material 8 to be rolled has reached directly below the finishing input thermometer 15. The longitudinal pattern of the temperature just before winding of the material to be rolled 8 is set, and calculation of the spray pattern of the water injection bank in the longitudinal direction of the material to be rolled 8 to achieve it is started.

  The calculation of the spray pattern of the water injection bank is performed similarly by transmitting the longitudinal pattern of the temperature immediately before winding the target rolled material 8 and the temperature after finish rolling of the target rolled material 8, which are also transmitted from the business computer 90. Measured with a finish-side thermometer 15 based on the longitudinal pattern, the thickness of the rolled material (hot rolled metal strip) 8 after finish rolling, the threading speed of the rolled material 8, and the top speed of the rolled material 8. This is calculated in the process computer 70 on the basis of the actual temperature distribution in the longitudinal direction on the entry side of the finishing mill 18 of the rolled material 8.

  Here, for the longitudinal pattern of the temperature immediately before winding the rolled material 8 as a target, a setting table is provided in the business computer 90 and data such as the material of the rolled material 8 and the thickness and width after finish rolling are provided. The key is set for each of the tip, middle, and tail ends of the material 8 to be rolled. However, the present invention is not limited to this, and a setting table may be provided in the process computer 70 for setting.

  Further, as shown in FIG. 2, the threading speed and the top speed of the material 8 to be rolled are in the acceleration / deceleration pattern when the material 8 is finish-rolled. Acceleration is started immediately after the tip of the material to be rolled 8 is advanced and wound around the coiler 24 at a low speed for preventing bumping when biting into each stand of the rolling mill 18. However, a high speed for performing temperature drop compensation for the purpose of securing the material of the material to be rolled is referred to as a top speed.

  In FIG. 2, the threaded plate 8 is threaded at a threading speed from when the tip of the material 8 is turned on to the F1 stand of the finishing mill 18 (a) until when the tip is wound around the coiler 24 (b). Accelerate immediately after winding around 24, and maintain the top speed until the tail end of the material 8 is turned off from the F1 stand (c), and creeping is completed until the tail end winding is completed (d) The board is decelerated to a speed called speed.

  Now, returning to the calculation of the spray pattern of the irrigation bank in the process computer 70, the spray pattern of the irrigation bank can be used for all bank injection, all bank non-injection, half of the bank injection, etc. In one example, it is decided first.

Then, the distance (water injection length L) from the position where the water injection start bank starts to the position where the water injection end bank ends when the spray pattern of the water injection bank determined in accordance with the provisionally determined spray pattern is followed.
Furthermore, when the spray pattern of the water injection bank determined in advance is followed, how much the temperature immediately before winding the rolled material 8 will be calculated.

  First, as shown in FIG. 3 (b), it is considered that a cut plate 8a obtained by virtually dividing the material to be rolled (hot rolled metal strip) 8 in the longitudinal direction is continuous, and a single cut plate 8a is taken up. In addition, where the cut plate 8a is located in the longitudinal direction in the material 8 to be rolled, and in which state the rolled material 8 is in the state of the material 8 to be rolled before the start of finish rolling, it corresponds to the rough side rolled material at that position. Subsequent calculations are performed based on the data of how much the material temperature was (measured by the finishing input thermometer 15).

  Now, when each cut plate 8a reaches directly under the finishing delivery thermometer 21, it is temporarily determined that it will follow the longitudinal pattern of the temperature after finishing rolling of the target material 8 to be rolled.

  Based on the threading speed, the top speed, and the mechanical distance between the components, the time required to reach the main components (F1, F7, the entry side and the exit side of the run-out table 23) is reached. Next, based on the required time, the run-out table 23 is allowed to cool down until it reaches the entrance side of the cooling-related equipment 26 that directly contributes to the cooling (extension zone) of the cooling-related equipment 26 (cooling zone). The temperature of the material 8 to be rolled, the descaling water by the descaling device 16, and the material to be rolled 8 by cooling water injection from a cooling device (not shown) installed between the rolling mills constituting the finish rolling mill 18. Temperature fluctuations such as a temperature drop and a temperature rise of the material 8 to be rolled due to processing heat generated during finish rolling are calculated for each of the cut plates 8a, and the cut plates 8a substantially contribute to cooling in the run-out table 23. That, cooling facilities 26 directly below the zone extending either to a temperature of several ℃ when it reaches the entry side of the (cooling zone), predicted by calculation without detailing.

  In addition, the following is an outline of how much each cut plate 8a is cooled to below the temperature in the zone immediately below where the cooling-related equipment 26 is present, according to the spray pattern of the water injection bank determined as described above. Predict by the calculation logic described.

  The temperature of the hot-rolled metal strip (rolled material) 8 is represented by a one-dimensional heat conduction equation in the plate thickness direction shown in the following formula (3).

The boundary condition at the surface of the hot-rolled metal strip (rolled material) 8 and the center in the plate thickness direction is given by the following formula (4), assuming that the cooling of the upper surface and the lower surface is symmetric.

Here, T is the temperature of the hot-rolled metal strip (rolled material) 8, Tw is the cooling water temperature, c is the specific heat, ρ is the density, λ is the thermal conductivity, Qtrans is the transformation heat generation, h is the heat transfer coefficient, d is a plate thickness, x is a plate thickness direction coordinate, and t is time.

  The heat transfer coefficient h on the surface of the hot-rolled metal strip (rolled material) 8 is obtained by the following formula (5) as the sum of each term of radiation, convection, and water cooling.

Here, he is a heat transfer coefficient by radiation, ha is a heat transfer coefficient by convection, and hwt and hwb are heat transfer coefficients by upper surface water cooling and lower surface water cooling. As for the heat transfer rates hwt and hwb, a function of the water flow density W of the cooling water, the water temperature Tw, the surface temperature Ts of the hot-rolled metal strip (rolled material) 8, and the conveyance speed V of the hot-rolled metal strip (rolled material) 8 Is given by the following equation (6).

  By calculating the volume fraction of the transformation phase such as ferrite, pearlite, and bainite in the cooling process, the transformation rate is estimated, and the transformation heat generation Qtrans is calculated as in the following formula (7).

Here, ξ is the transformation latent heat, and X is the transformation rate.

  By the convergence calculation shown in the flowchart of FIG. 4, whether or not the bank where the cooling water is poured when passing through the run-out table 23 can cool the cut plate 8a to the target temperature just before winding. Ask.

  That is, when the spray pattern of the water injection bank determined in advance is followed (initial setting of the cooling bank in FIG. 4), the total number of water injection banks in accordance with the spray pattern of the water injection bank determined temporarily The amount of cooling water flow and the time required for the cut plate 8a to pass through a zone corresponding to the total number of water injection banks are the above-mentioned threading speed, top speed, and mechanical distance between each component. Based on the result of the prediction calculation (prediction of the cooling time in each bank in FIG. 4) based on the above-described equation (3), how much the cut plate 8a is cooled immediately before winding in that time. ) To (7) calculated (prediction of coiling temperature in FIG. 4), and still exceeds a certain value (for example, ± 5 ° C.) compared to the target temperature just before coiling. If the When pouring water the click, or immediately if if the upstream side of the bank was stopped water injection, and then calculate, obtained by convergence calculation repeating a series of calculations process called. The obtained result corresponds to the bank selection preset in FIG.

  The spray pattern (bank selection preset result) of the water injection bank that has been converged and corrected in this way is transmitted to the control device 50, and the control device 50 uses the corrected water injection bank spray pattern thus transmitted, The flow rate of the cooling water poured from the cooling-related equipment 26 toward the material to be rolled 8 is controlled. If the total number of water injection banks changes, the flow rate of cooling water also changes.

  Specifically, a lot of data is transmitted to the control device 50 based on the computer setting of the bank for injecting cooling water and the target cutting plate 8a, and the control device 50 supplies the cooling water for the cutting plate 8a in real time. The arrival to each bank to be injected is determined based on tracking using both the measuring roll 28 and the speedometer 29, and the delay time from the opening and closing of the valve to the start and stop of injection of cooling water is appropriately taken into account. In accordance with the arrival timing, the opening and closing of the valves for starting and stopping the injection of the cooling water in each header of each bank is controlled.

(Cooling control method for hot-rolled metal strip according to the present embodiment)
Here, the description will be shifted to the cooling control method for the hot-rolled metal strip according to the present embodiment.

  One requirement is to divide the zone immediately below the zone (cooling zone) of the cooling-related equipment 26 between the finishing mill and the coiler of the hot rolling line into two zones, the first zone and the second zone. In the latter half zone, the temperature of the hot rolled metal strip immediately before winding is controlled by, for example, the above-described series of primitive hot rolled metal strip cooling control methods. In addition to that, based on the results of temperature measurements with a near-infrared camera that can shoot the full width or part of the full length of the hot-rolled metal strip installed on the exit side of the first half zone. The purpose is to provide feedback to control the temperature of the hot-rolled metal strip in the first half zone.

  That is, as shown in FIG. 1 (a), the near-infrared camera capable of photographing the entire width of the hot-rolled metal strip installed on the exit side of the first half zone for the entire length or a part of the total length, Even when a part of the hot-rolled metal strip after finish rolling comes to the point where nucleate boiling starts and the temperature of the hot-rolled metal strip becomes non-uniform (particularly in the width direction), the temperature is measured. Based on the above results, the temperature distribution of the hot-rolled metal strip can be made uniform by feeding back to the control of the temperature of the hot-rolled metal strip in the first half zone so that the number of headers for cooling water injection is somewhat reduced. Can be realized.

  Where to divide the first half zone and the second half zone is based on the concept described below.

  As will be described later, in the region where the surface temperature of the hot-rolled metal strip is high, film boiling occurs and the heat flux is low. In general cooling-related equipment such as a pipe laminar system, depending on the water density, transition boiling (at some part of the hot-rolled metal zone, nucleate boiling occurs at a certain temperature between 500 and 550 ° C). The heat flux increases as the temperature decreases.

  If the cooling in the first half zone is not stopped before the transition boiling starts, a region that is locally lower than the average temperature of the surface of the material to be rolled tends to be formed, and this temperature deviation is caused by uneven temperature just before winding and It also affects the non-uniformity of the product hot rolled metal strip.

  Therefore, considering the safety side, the length of the first half zone in the direction of the material to be rolled is determined so that cooling can be performed until the temperature of the hot-rolled metal strip reaches 550 ° C.

  The length varies depending on the thickness of the hot-rolled metal strip, the conveyance speed, the target post-finishing temperature, etc., so the entire material to be rolled (product mix) rolled in the target hot rolling line Among them, if the ratio of the target post-finishing temperature to the product of the thickness and the conveyance speed is the maximum, the case where the maximum cooling water temperature that can be assumed is cooled to 550 ° C. is determined as a critical condition. Good.

  In addition, the above-mentioned determination is not limited to the entire material to be rolled to be rolled in the target hot rolling line, but is limited to the material to be rolled that requires strictly uniform temperature immediately before winding. You may do it.

  The length of the run-out table (the length from the final stand constituting the finishing mill to the coiler on the side closer to it) varies depending on the hot rolling line, and is 130 to 195 m. Is 70 m, but is not limited to this embodiment.

  Incidentally, as an example of the length in the transport direction of the latter half zone, 30 m is mentioned, but it is not limited to the present embodiment.

  An air cooling zone may be provided between the first half zone and the second half zone.

  Even in a part of the hot-rolled metal strip after finish rolling, a portion where nucleate boiling starts and the temperature of the hot-rolled metal strip becomes uneven is determined as follows.

  First, the average temperature of the surface of the hot-rolled metal strip is calculated for each image taken in the field of view of the near-infrared camera. Then, a temperature deviation from the average temperature (average value−minimum value) is calculated, and a region on the low temperature side (low temperature region) is determined from the average temperature.

  As described above, such a low temperature region often has a pool of cooling water locally at the tip of the material 8 to be rolled as shown in FIG. This is caused by the fact that the temperature distribution in the width direction becomes uneven and the temperature distribution in the width direction becomes non-uniform.

  The reason why it is necessary to discriminate a region on the low temperature side (low temperature region) from the average temperature is as follows.

In particular, when the cooling water is slowly cooled by supplying water with a water density of 0.05 m ³ / m ² / min or more and less than 0.3 m ³ / m ² / min per front and back surfaces in the latter half zone, If there is a region on the low temperature side (low temperature region), the first half zone and the second half are obtained by connecting the temperature measured in one pixel in the longitudinal direction of the material 8 to be rolled in the width direction of the material 8 in FIG. Although it is shown in comparison with the zone, as can be seen by comparing the temperature deviation from the average temperature (average value-minimum value) at two locations, a large portion and a small portion, the temperature deviation is a certain constant. If the value is larger than this value, the temperature deviation from the average temperature will increase due to cooling, and the temperature just before winding will be far from the target value and will not be within the allowable range. Will not be within the allowable range.

  Moreover, as shown in FIG. 6, the tendency becomes more prominent as the target temperature immediately before winding (labeled CT in the figure) becomes lower.

  In this regard, when the temperature deviation from the average temperature (average value−minimum value) is small, the expansion of the temperature deviation is relatively small.

  The presence or absence of a region in which the temperature deviation in this low temperature region is equal to or greater than the threshold ΔTL of the allowable temperature deviation after cooling in the first half zone, which will be described below, is set on the outlet side of the first half zone. The determination is made based on the result of measurement by a near-infrared camera capable of photographing the full width, or the full length or a part of the full length.

  The threshold for determining that the temperature of the hot-rolled metal strip has become non-uniform is the lower limit of the allowable range of the same temperature sandwiching the temperature immediately before winding of the target hot-rolled metal strip, which is necessary for the material, The standard deviation σc of the accuracy of the temperature just before winding between the hot rolled metal strips and the temperature at the center of the hot rolling line of the hot rolled metal strip after finish rolling are within the material to be rolled. It is determined from the standard deviation σL of how much it varies in the longitudinal direction, the standard deviation σw of how much the temperature of the hot-rolled metal strip after finish rolling varies in the width direction, and the like.

  A value (tolerance) obtained by subtracting the lower limit value of the allowable range of the temperature from the temperature immediately before winding of the target material to be rolled, which is necessary for the material, is X (in many cases 60 ° C., for example, 40 ° C. or lower) Is more preferable.), It is necessary to satisfy the following formula.

X ≧ 3.0 × √ (σc ^ 2 + σL ^ 2 + σw ^ 2)
Therefore, the standard deviation σw of the non-uniformity in the width direction of the temperature of the hot-rolled metal strip due to transition boiling needs to satisfy the following equation.

σw ≦ √ [(X / 3.0) ^ 2 − (σc ^ 2 + σL ^ 2)]
Therefore, if the threshold value ΔTL is determined to be equal to 2.5 times σw,
ΔTL = 2.5 × √ [(X / 3.0) ^ 2− (σc ^ 2 + σL ^ 2)] (0)
It becomes.

  For example, a value (tolerance) X obtained by subtracting the lower limit value of the allowable range of the same temperature from the temperature immediately before winding of the target material to be rolled, which is necessary for the material, is 60 ° C., and the temperature control accuracy σc is 5 ° C. When σL is 8 ° C., the threshold ΔTL is 44 ° C.

  Of the whole material to be rolled (product mix) rolled in the target hot rolling line, the temperature control accuracy σc, σL is analyzed for each material to be rolled having the same material and dimensions after finish rolling, and the target material FIG. 7 shows an example of a result obtained by calculating ΔTL using a value (tolerance) X (60 ° C.) obtained by subtracting the lower limit value of the allowable range of the temperature from the temperature immediately before winding the rolled material. It can be seen that the threshold ΔTL decreases as the temperature immediately before winding decreases.

  The temperature control accuracy σc, not limited to the entire material to be rolled to be rolled in the target hot rolling line, but particularly to the material to be rolled that is strictly required to have a uniform temperature immediately before winding. While analyzing σL and obtaining the threshold value ΔTL, the method for controlling cooling of a hot-rolled metal strip according to the present embodiment may be applied only to the material to be rolled.

  By the way, if feedback control is performed so as to reduce the number of headers for injecting cooling water in the first half zone, the temperature immediately before winding the hot-rolled metal strip increases by the reduced amount. If it is larger than a certain level, it is preferable to feed-forward control to cooling in the latter half zone to compensate for that, and to somewhat increase the number of headers for injecting cooling water in the latter half zone.

  Each operation amount is calculated by the equations (1) and (2), and is controlled by increasing or decreasing the number of water injection banks corresponding to the amount of change in the water injection flow rate. Note that ΔT indicates how much the lowest temperature in the field of view of the near-infrared camera is lower than the average temperature, and the deviation thereof.

  By the way, the size of the field of view is a width that covers the maximum width of 2300 mm in the width direction of the hot-rolled metal strip, and a length corresponding to the transport speed of the hot-rolled metal strip in the transport direction. As will be described later, an example is 3200 mm.

  Further, it is preferable that the number of visual fields can be continuously photographed in the longitudinal direction of the hot-rolled metal strip so that the entire length of the hot-rolled metal strip or a part of the entire length can be photographed.

  For example, when the conveyance speed of the hot-rolled metal strip is 1200 mpm, the temperature distribution data of the full length is measured every 3200 mm in the conveyance direction, that is, in the longitudinal direction of the material 8 to be rolled, by photographing once every 0.16 sec. Can continue.

  The temperature deviation from the average temperature on the surface of the hot-rolled metal strip (average value−minimum value) is not equal to or greater than the predetermined threshold value ΔTL. In such a case, there is no concern because the function of performing feedback control functions separately based on the temperature measurement result at the center of the width of the hot rolling line.

(In the case of slow cooling in the second half zone)
As for the cooling method in the latter half zone, as one idea, the water density per front and back side is lowered to 0.05 m ³ / m ² / min or more and less than 0.3 m ³ / m ² / min to perform slow cooling. There is a way to do so.

  Here, the water density is a value obtained by dividing the flow rate of the cooling water supplied to the hot-rolled metal strip per unit time by the area of the hot-rolled metal zone to which the cooling water is supplied.

  Moreover, as long as it exists in the said water amount density range per front and back single side | surface, both surfaces may be in the said water amount density range separately. In some cases, it is advantageous to increase the cooling capacity.

  Further, the above-described cooling control method for a hot-rolled metal strip according to the present embodiment, that is, feedback to the control of the temperature of the hot-rolled metal strip in the first half zone is applied to a hot-rolled metal strip. However, if the next hot-rolled metal strip has the same material and dimensions, based on the result of temperature measurement in one image of the hot-rolled metal strip described above and taken in the field of view of the near-infrared camera. Calculating a deviation obtained by subtracting a minimum value of the temperature in the one image from the average temperature of the hot-rolled metal strip and the average temperature, and the deviation is calculated in the hot-rolled metal strip by the feedback. The width of the hot rolling line on the outlet side of the first half zone of the hot-rolled metal strip after the time when the temperature of the rolled metal strip becomes less than a threshold value ΔTL for determining that the temperature in the width direction has become uneven. Longitudinal average of temperature measurement results at the center As described above, the cooling control for the next hot-rolled metal strip is performed as the target value of the temperature at the center of the width of the hot rolling line on the outlet side of the first half-zone of the next hot-rolled metal strip. It is also preferable to do so.

  By doing so, the temperature of the hot-rolled metal strip on the exit side of the first-half zone becomes difficult to enter the transition boiling region even at the tip of the hot-rolled metal strip, and the temperature just before winding is also within the allowable range. This is because it becomes easier.

(In the case of strong cooling in the second half zone)
The inventors have also conceived another preferred embodiment based on the following newly discovered facts.

The newly discovered fact is that the water density is 0.05 m ³ / m ² / min or more 0 in the temperature range where nucleate boiling starts in a part of the hot-rolled metal zone, as in Patent Document 1. .3m ³ / m ² / min. When the cooling rate is less than ³ m ³ / min and the cooling is performed slowly, the water density is 2.0 m ³ / m ² / min or more per side. The temperature of the hot-rolled metal strip immediately before winding is uniform.

  In the region where the surface temperature of the hot-rolled metal strip is high, film boiling occurs and the heat flux is low. In general cooling-related equipment such as a pipe laminar system, depending on the water density, transition boiling (at some part of the hot-rolled metal zone, nucleate boiling occurs at a certain temperature between 500 and 550 ° C). The heat flux increases as the temperature decreases.

  However, according to the inventors' research, as shown in FIG. 8, as the water density for cooling increases, the transition boiling start temperature gradually increases and the hot-rolled metal strip is not a part. It was found that the temperature at which nucleate boiling over the entire surface gradually increases.

  Moreover, what is important here is that when the water density for cooling is increased, it acts not only on a part of the hot-rolled metal strip but also on the entire surface to nucleate boiling.

Therefore, until the temperature of the hot-rolled metal strip reaches the transition boiling start temperature of 500 to 550 ° C. after the finish rolling, as defined as another requirement of the present embodiment, the pipe in the first half zone Cooling is performed so that the water density is 0.7 m ³ / m ² / min or more and 1.2 m ³ / m ² / min or less per one side of the front and back surfaces by general cooling-related equipment such as a laminar method. In the temperature range, if the water density is rather increased and cooling is performed in a state where it has completely shifted to nucleate boiling, the hot rolling associated with the injection of cooling water in the temperature range where the hot-rolled metal strip is in the transition boiling state. It is also possible to suppress the temperature non-uniformity of the metal strip immediately before winding.

  Here, the result of investigating the relationship between the specific water density and the transition boiling start temperature in the laboratory will be described.

  In FIG. 9, the water density (cooling in which water is injected per unit area of the hot-rolled metal strip) by a nozzle in which a plurality of circular jets are arranged in the width direction and the longitudinal direction of the hot-rolled metal strip (hot-rolled steel strip) in the laboratory. The flow of water) is changed, and the transition boiling start temperature and nucleate boiling start temperature are read from the cooling temperature history.

First, as the water density is increased, the transition boiling start temperature and the nucleate boiling start temperature are increased. To ensure nucleate boiling at 500 ° C. or higher, the water density is set to 2.0 m ³ / m ² / min or higher. You can see that

In addition, when cooling is performed so that the water density is 0.7 m ³ / m ² / min or more and 1.2 m ³ / m ² / min or less by a general cooling-related facility such as a pipe laminar method. It can be seen that the transition boiling start temperature is 500 to 550 ° C.

That is, as the cooling-related equipment in the first half zone, using a conventional one such as a pipe laminar method, after the finish rolling, the temperature of the hot-rolled metal strip is 500 to 550 ° C. The transition boiling start temperature As a cooling-related equipment in the latter half of the zone, hot-rolled metal is used as a cooling-related equipment that has been specially devised so that the water density is 2.0 m ³ / m ² / min or more. Cooling is performed after the temperature of the belt has fallen below the transition boiling start temperature.

According to the knowledge obtained in FIG. 9, as in Patent Document 1, in the latter half zone, the water density is 0.05 m ³ / m ² / min or more and less than 0.3 m ³ / m ² / min. When cooling is performed, the transition boiling start temperature can be lowered to 400 ° C. Therefore, when the target temperature immediately before winding is 400 ° C or higher, the temperature of the hot-rolled metal strip immediately before winding. It is possible to suppress non-uniformity.

  The above method is also preferable if the temperature of the hot-rolled metal strip immediately before the target winding is 400 ° C. or higher.

  However, when cooling to a temperature below that, the hot rolled metal strip is cooled in a state where a part of the hot rolled metal strip enters the transition boiling region, and the water density is not so large. There is a risk of non-uniformity.

  In this regard, according to the preferred embodiment described above, even if the target value of the temperature immediately before winding is lowered within the range up to room temperature, the temperature non-uniformity immediately before winding is suppressed. can do.

Water density per side of front and back as a cooling related equipment in the second half zone is 2.0m ³ / m ²
As for the device with a special devise such that it becomes / min or more, the upper surface of the hot-rolled metal strip is preferably a laminar one having excellent straightness or jet cooling.

Although there is no upper limit to the water density of the cooling-related equipment in the latter half zone, even if various ideas described later are applied, the method that can be realized by the inventors is 7.0 m ³ / m. ² / min or less.

In a preferred embodiment, the water density per front and back single side in the latter half zone is set to 2.0 m ³ / m ² / min or more. When cooling water having such a large water density is sprayed onto the hot rolled metal band, the hot rolled metal band Since the cooling water is drained only on the side surface of the hot-rolled metal strip, a thick water film is formed on the hot-rolled metal strip.

  If the cooling water penetrates this water film and does not generate a direct striking force on the hot rolled metal strip, even if the cooling water having such a large water density is jetted, it is only in a part of the hot rolled metal strip. There is a possibility that it will not boil. Therefore, a laminar shape with high straightness or jet cooling in which cooling water is injected from a jet nozzle is preferable. As the shape of the nozzle, a circular tube shape or a slit shape can be considered, but either one may be used.

  Use of spray or mist cooling is not preferable because the cooling water sprayed from the nozzle is divided into droplets and easily decelerates due to air resistance.

(Preferred cooling device for use in the latter half zone)
As various embodiments of a cooling device preferable for use in the latter half zone, for example, the one of Patent Document 5 describing an example applied to a thick plate rolling line is used for producing a hot-rolled metal strip. It is preferable to divert to a hot rolling line.

  FIG. 10A is a view for explaining an example of an embodiment of a cooling device preferable for use in the latter half zone.

  The cooling device 201 according to this embodiment is a cooling device installed in a hot rolling line such as the hot rolling line 100 shown in FIG. 31, and the material to be rolled 8 conveyed on the table roller 13. An upper header unit 210 for supplying rod-shaped cooling water toward the upper surface is provided.

  The upper header unit 210 includes a first upper header group composed of a plurality of first upper headers 210a arranged in the transport direction, and a second upper header composed of a plurality of second upper headers 210b arranged downstream in the transport direction. The upper headers 210a and 210b of the first upper header group and the second upper header group are each independently turned ON / OFF control of the injection (water injection) of the rod-shaped cooling water (start and stop of water injection) The piping configuration is provided with an ON-OFF mechanism 300 that enables the control of the above. Here, the first upper header group and the second upper header group are each composed of three upper headers.

  A plurality of rows of upper nozzles 220 (here, four rows in the conveyance direction of the material 8 to be rolled) are attached to the upper headers 210a and 210b, respectively. The first upper nozzle group) 220a and the upper nozzle group (second upper nozzle group) 220b of the second upper header 210b are arranged such that the injection directions of the rod-shaped cooling water 230a and the rod-shaped cooling water 230b sprayed from the rolled material 8 are They are arranged so as to face each other in the transport direction. That is, the first upper nozzle group 220a injects the rod-shaped cooling water 230a obliquely toward the downstream side of the upper surface of the material to be rolled at an inclination angle (injection angle) of θ1, and the second upper nozzle group 220b is upstream of the upper surface of the material to be rolled. The rod-shaped cooling water 230b is jetted obliquely toward the side at an inclination angle (jet angle) of θ2.

  Therefore, the rod-shaped cooling water from the upper nozzle of the farthest row (outermost row) when viewed in the conveying direction of the material to be rolled 8 from the upper header of each other is sandwiched between the positions where the rod-shaped cooling water collides with the material to be rolled 8. The area is the cooling area.

  At that time, if the injection line of the rod-shaped cooling water 230a from the first upper nozzle group 220a and the injection line of the rod-shaped cooling water 230b from the second upper nozzle group 220b do not intersect, the rolling is performed from the upper header of each other. As shown in FIG. 10, in a region sandwiched between positions where the rod-shaped cooling water from the upper nozzle in the closest row (innermost row) as viewed in the conveying direction of the material 8 collides with the material 8 to be rolled. The water film of the staying cooling water 240 is stably formed.

  Thereby, the rod-shaped cooling water from the upper nozzle on the side closest to the upper header of each other (innermost row) is jetted toward the water film of the staying cooling water 240, and the other rod-shaped water is mutually connected. It is preferable because the cooling water is not broken.

  And the space | interval of the position where rod-shaped cooling water collides with the to-be-rolled material 8 from the upper nozzle of the innermost row shall be called the residence area length L. In this staying area length L, the rod-shaped cooling water does not collide with the material to be rolled 8 and is cooled only by the staying cooling water 240, so that the contact between the material to be rolled 8 and the cooling water is unstable and the temperature is not uniform. However, if the staying zone length L is set to 1.5 m or less, the rate at which the staying cooling water 240 cools the material 8 to be rolled is relatively small. Uniformity can be prevented. As described above, the length L of the staying region is preferably short, and more preferably about 100 mm.

  Incidentally, the rod-shaped cooling water refers to cooling water ejected from a circular (including elliptical or polygonal) nozzle outlet. In addition, the rod-shaped cooling water is not a spray-like jet, but a film-like laminar flow, and the cross section of the water flow from the nozzle outlet to the material to be rolled 8 is maintained in a substantially circular shape. Cooling water with a water flow.

  FIGS. 10B and 10C show examples of arrangement of the upper nozzles 220 (220a and 220b) attached to the upper header 210 (210a and 210b). A row of nozzles arranged in a row at a fixed mounting interval in the width direction of the material to be rolled 8 so that rod-shaped cooling water can be supplied to the entire width of the material to be rolled 8 passing therethrough is in the conveying direction A of the material to be rolled 8. A plurality of rows (here, 4 rows) are provided.

  Furthermore, here, the width direction collision position of the rolled material 8 of rod-shaped cooling water sprayed from the nozzle in the next row with respect to the width direction collision position of the rolled material 8 of rod-shaped cooling water sprayed from the nozzle in the front row is here. Nozzles are arranged so as to be displaced.

  That is, in FIG. 10B, the position in the width direction of the nozzle in the next row is shifted by about 1/3 of the width direction attachment interval with respect to the nozzle in the previous row, and in FIG. / It is shifted about 2

  In addition, although mentioned later, when giving the width direction component of the to-be-rolled material 8 to the rod-shaped cooling water sprayed from a nozzle, the width direction attachment position of the to-be-rolled material 8 of a nozzle and the width of the to-be-rolled material 8 of rod-shaped cooling water. Since the direction collision position is different, in that case, it is necessary to adjust the nozzle mounting position so that the width direction collision position of the rolled material 8 of the rod-shaped cooling water becomes a desired position (distribution). .

  As described above, a plurality of rows of upper nozzles 220 are arranged in the conveying direction because one row of upper nozzles dams up the stagnant cooling water between the rod-shaped cooling water that collides with the material to be rolled 8 and the adjacent rod-shaped cooling water. The power to stop and drain the water is weakened. In order to block the accumulated cooling water, a plurality of upper nozzles are necessary, and the number of upper nozzles 220 attached to each upper header 210 is preferably three or more, and more than five. More preferable.

  Further, as described above, attaching the upper nozzle 220 separately to the plurality of upper headers 210 is indispensable for performing temperature control of the hot-rolled metal strip.

  In the hot-rolled metal strip, it is necessary to cool the hot-rolled metal strip of various thicknesses to a target temperature, but it is necessary to cool at the fastest possible conveyance speed in order to secure the production amount.

  Therefore, in order to adjust to the target temperature, it is necessary to adjust the water cooling time. Therefore, in general, it is necessary to change the length of the cooling region in various ways.

  For this reason, the length of the cooling region is changed by attaching the upper nozzle to a plurality of upper headers, and making the structure so that each upper header can turn on and off the injection of the rod-shaped cooling water.

  One or more upper nozzles may be attached to each upper header, but the number of nozzle rows to be attached is determined according to the target temperature control capability.

  When the range of allowable temperature deviation (for example, ± 8 ° C.) is wider than the temperature (for example, 5 ° C.) at which the material to be rolled 8 is cooled per row, it can be adjusted to the allowable temperature deviation range. The number of nozzle rows per header may be increased within the limit.

  For example, in order to adjust to a temperature deviation range of ± 8 ° C. (temperature range of 16 ° C.), the temperature drop due to cooling in one upper header may be less than 16 ° C. For that purpose, it is attached to the upper header If the number of upper nozzle rows is 3, the temperature can be adjusted in units of 15 ° C., so that it is possible to adjust the temperature of the hot-rolled metal strip after cooling to an allowable temperature deviation range.

  Conversely, if the number of upper nozzle rows attached to the upper header is four in this case, the temperature adjustment is in units of 20 ° C, which may not be within the target temperature deviation range (16 ° C), which is not preferable. .

  Therefore, it is necessary to adjust the number of upper nozzle rows per upper header depending on the temperature that can be cooled by the cooling device and the range of allowable temperature deviation.

  As described above, the number of the upper headers 210 and the number of the upper nozzles 220 are determined so as to satisfy both the viewpoint of blocking the accumulated water and the viewpoint of obtaining a desired cooling capacity.

And this cooling device 201 is rod-shaped cooling from the upper headers 210a and 210b toward the upper surface of the material 8 to be rolled so that the water density on the upper surface of the material 8 to be rolled becomes 2.0 m ³ / m ² / min or more. Water 230 is supplied.

Here, the reason why the water density is 2.0 m ³ / m ² / min or more will be described. The staying water 240 shown in FIG. 10 is formed by damming with the rod-shaped cooling waters 230a and 230b to be supplied.

  At this time, if the water density is small, damming itself cannot be performed, and if the water density becomes larger than a certain amount, the amount of stagnant water 240 that can be dammed increases and is discharged from the width end of the material 8 to be rolled. The amount of the staying water 240 is kept constant by balancing the flow rate of the cooling water supplied and the flow rate of the supplied cooling water.

In the case of a hot-rolled metal strip, the general width is 0.9 to 2.3 m, and if it is cooled at a water density of 2.0 m ³ / m ² / min or more, the staying cooling water 240 is constant in these widths. Can be maintained.

As the water density is increased to 2.0 m ³ / m ² / min or more, the cooling rate of the hot-rolled metal strip increases, so the length of the cooling region necessary for cooling to the target temperature is shortened. can do.

  As a result, the space for introducing the cooling device 201 can be made compact, and the cooling device 201 can be introduced between existing facilities and cooled together. Leads to savings.

Thus, in this cooling device 201, the rod-shaped cooling water 230a ejected from the first upper nozzle 220a and the rod-shaped cooling water 230b ejected from the second upper nozzle 220b are opposed to each other in the conveying direction of the material 8 to be rolled. Therefore, the injected rod-like cooling water 230a, 230b itself blocks the stagnant water 240 on the upper surface of the material 8 to be moved in the conveying direction of the material 8 to be rolled. Thus, even when cooling water having a large water density of 2.0 m ³ / m ² / min or more is supplied, a stable cooling region can be obtained and uniform cooling can be performed.

  In addition, the cooling water sprayed from the upper nozzles 220a and 220b is not a film-like cooling water sprayed from, for example, a slit nozzle, but a rod-shaped cooling water because the rod-shaped cooling water can stably form a water flow. This is because the power for blocking the accumulated cooling water is great.

  In addition, when the film-like cooling water is injected obliquely, the water film becomes thinner as the distance from the material to be rolled 8 to the nozzle becomes longer, and the water film becomes thinner and more fragile.

  The injection angle θ1 of the first upper nozzle 220a and the injection angle θ2 of the second upper nozzle 220b are preferably 30 to 60 °.

  If the injection angles θ1 and θ2 are smaller than 30 °, the vertical velocity components of the rod-shaped cooling waters 230a and 230b become small, the collision with the material to be rolled 8 becomes weak, and the cooling capacity decreases. This is because if θ1 and θ2 are larger than 60 °, the speed component in the conveying direction of the rod-shaped cooling water becomes small, and the force to dam the stagnant cooling water 240 becomes weak. The injection angle θ1 and the injection angle θ2 are not necessarily equal.

  Further, in order to block the accumulated cooling water, it has been described that a plurality of rows in the longitudinal direction (three or more rows are jetted as described above), but the jet speed of the rod-like cooling water jetted from the upper nozzle 220 is 8 m / s or more. Then, the retention effect of the retained water is further improved, which is preferable.

  In order to prevent the nozzle from being clogged and to ensure the injection speed of the rod-shaped cooling water, the inner diameter of the upper nozzle 220 is preferably in the range of 3 to 8 mm.

  Moreover, in the case of rod-shaped cooling water, the cooling water tends to flow out from the gap between the rod-shaped cooling water and the rod-shaped cooling water adjacent in the width direction.

  In this case, as shown in FIGS. 10B and 10C described above, the width direction of the rolled material 8 in the next row of rod-shaped cooling water with respect to the collision position in the width direction of the rolled material 8 in the next row of rod-shaped cooling water. It is preferable to dispose the collision position. As a result, the rod-shaped cooling water in the next row collides with a portion where the drainage capability is weakened between the rod-shaped cooling waters adjacent in the width direction, and the drainage capability is complemented.

  And if the attachment pitch (width direction attachment space | interval) of the width direction of the upper nozzle 220 shall be 20 times or less with respect to a nozzle internal diameter, favorable draining property can be obtained.

  Furthermore, in order to prevent the upper nozzle 220 from being damaged due to warpage of the material 8 to be rolled, it is preferable that the position of the tip of the upper nozzle 220 be separated from the pass line. In order to disperse, the distance between the tip of the upper nozzle 220 and the pass line is preferably set to 500 mm to 1800 mm.

  Moreover, as shown in FIGS. 11 (a), (b) and (c), 0 to 35% of the speed component in the injection direction of the rod-shaped cooling water is a speed component toward the width direction of the material 8 to be rolled. When the injection direction of the rod-shaped cooling water is set with the outward angle α, the rod-shaped cooling water injected from the upper nozzle 220 onto the material to be rolled 8 is indicated by the arrows in FIGS. 11 (a), 11 (b), and 11 (c). Compared to the case where the bar-shaped cooling water does not have a velocity component toward the outer side in the width direction of the material 8 to be rolled, as shown in B, and quickly falls from the width end of the material 8 to be rolled. Since it becomes possible to drain water by damming up the stagnant water with a low pressure or a small amount of water, it is preferable for economical design.

  A more preferable range is 10 to 35%. In addition, if it exceeds 35%, the apparatus cost is required for preventing scattering of the cooling water in the width direction of the material 8 to be rolled, and the vertical velocity component of the rod-shaped cooling water becomes small, so that the cooling capacity is lowered.

  Moreover, it is preferable that 40 to 60% of the total number of nozzles arranged in the width direction of the material to be rolled 8 inject the rod-shaped cooling water having a component toward one outer side in the width direction of the material to be rolled 8.

  If the number of nozzles facing one outer side in the width direction of the material to be rolled 8 exceeds 60% of the whole and deviation occurs in cooling water discharge from the width end, the thickness of the staying cooling water has increased. This is because the rod-shaped cooling water cannot dam the staying cooling water, and the temperature in the width direction may be uneven.

  Moreover, it is because the apparatus cost for preventing this will become high when splashed water increases excessively on one outer side of the width direction of the to-be-rolled material 8. FIG.

  Therefore, as shown in FIG. 11 (b), in the case of injecting with a constant outward angle α on both outer sides, the ratio of the nozzles injected on the outer side in the width direction of the material 8 to be rolled is up to 40% on one side and 60% on the opposite side. Can be arranged, but it is preferable to arrange 50% on one side and 50% on the opposite side.

  In addition, as shown in FIG. 11A, the outward angle α may be gradually increased toward the outer side in the width direction of the material 8 to be rolled, but in that case, with respect to the center in the width direction of the material 8 to be rolled. It is preferable to have a symmetrical distribution of outward angles α.

  Moreover, as shown in FIG.11 (c), the total number of the upper nozzles (outward angle (alpha) = 0 upper nozzle) which does not face the width direction outer side of the to-be-rolled material 8 shall be less than 20% (for example, 20%) of the whole. If the number of nozzles directed to both outsides is made substantially equal (for example, 40% on each side), the accumulated cooling water is drained smoothly, and it is suitable for draining the retained cooling water.

  Each cooling device 20 described above has three upper headers 21a and 21b as shown in FIG. 10. However, when the equipment length is made longer due to the cooling capacity, The number of upper headers 21a and 21b may be increased, and a plurality of cooling devices 20 may be installed in the transport direction A.

  Furthermore, as shown in FIG. 12, it is possible to provide intermediate headers 210c between the first upper header 210a and the second upper header 210b, and the number thereof may be any number.

  Here, the intermediate header 210c may have the same nozzle arrangement, outward angle α, water density, and the like as the first upper header 210a and the second upper header 210b except that the dip angle θ with respect to the transport direction is 90 °. . In that case, the number of the first upper header 210a and the second upper header 210b may be plural.

Thus, in each cooling device 20 described above, the first upper nozzle group 220a for injecting rod-shaped cooling water having a water density of 2.0 m ³ / m ² / min or more above the hot-rolled metal strip 8, A first upper header 210a and a second upper header 210b connected to the second upper nozzle group 220b are provided, and the tilt angles θ1 and θ2 formed by the rod-shaped cooling waters 230a and 230b and the material to be rolled 8 are 30 ° to 60 °, and the material to be rolled The first upper nozzle group 220a and the second upper nozzle group 220b are arranged so as to face each other in the conveyance direction A of the material 8, and the rod-shaped cooling water is further applied to the speed component in the traveling direction of the material 8 to be rolled. By spraying with a speed component of 0 to 35% outward in the width direction, cooling water is supplied to the upper surface of the material 8 to be rolled, so by installing it in the hot rolling line, Highly cooled the rolled material 8 to the target temperature It can be uniformly and stably cooled at a rate.

  In each cooling device 20 described above, when the speed of the rod-shaped cooling water 230a and 230b sprayed from the first upper nozzle group 220a and the second upper nozzle group 220b facing each other is high, for example, 10 m / s or more, The rod-shaped cooling water 230a and 230b collide with the material to be rolled 8 and then collide with each other and scatter upward.

  If this scattered cooling water falls on the stagnant cooling water 240, there is no problem, but as shown in FIG. 13, if the scattered cooling water 250 splashes obliquely upward and falls on the rod-shaped cooling water 230a, 230b, the scattered cooling water. There are cases where 250 leaks from the gap between the rod-shaped cooling water 230a and 230b and complete draining cannot be performed. In particular, when the staying zone length is within 200 mm, the problem is likely to occur. Furthermore, as the cooling water injection speed increases, the scattered cooling water 240 may jump over the first upper header 210a and the second upper header 210b and fall onto the material 8 to be rolled.

  On the other hand, the cooling device 201 shown in FIG. 14A is the cooling device 201 shown in FIG. 10A, and further, the innermost row of the opposed first upper nozzle group 220a and second upper nozzle group 220b. Further, shielding plates 260a and 260b are added to the inside. Here, the shielding plates 260a and 260b are preferably installed so as to cover the upper portions of the rod-shaped cooling waters 230a and 230b ejected from the first upper nozzle group 220a and the second upper nozzle group 220b.

  As a result, even when the scattered cooling water 250 is scattered obliquely upward, the falling scattered cooling water 250 is blocked by the shielding plates 260a and 260b, and does not fall on the rod-shaped cooling water 230a and 230b. To fall into. Therefore, it becomes possible to drain water accurately.

  The shielding plates 260a and 260b can be structured so that they can be moved up and down by the cylinders 270a and 270b. The shielding plates 260a and 260b are used only when manufacturing the products that require the shielding plates 260a and 260b. There is also a way to keep it.

  Incidentally, when using the shielding plates 260a and 260b, it is preferable that the lowermost ends of the shielding plates 260a and 260b be positioned 300 to 800 mm above the upper surface of the material 8 to be rolled. That is, if it is positioned 300 mm or more above the upper surface of the material 8 to be rolled, it will not collide even if the material 8 to be rolled up enters the tip or tail end. However, if the height is higher than 800 mm from the upper surface of the material 8 to be rolled, the scattered cooling water 250 cannot be sufficiently shielded.

  Further, instead of the shielding plates 260a and 260b in FIG. 14A, shielding curtains 280a and 280b having a light and smooth surface may be used as shown in FIG. 14B. The shielding screens 280a and 280b are normally in a suspended state and are lifted along the rod-shaped cooling water in the innermost row when the injection of the rod-shaped cooling water 230a and 230b is started. At that time, since the rod-shaped cooling water 230a and 230b are jetted vigorously, the flow is not disturbed.

  Furthermore, as described above, when the cooling water injection speed is high, the scattered cooling water 250 jumps over the first upper header 210a and the second upper header 210b and falls onto the material 8 to be rolled. As shown in FIG. 14C, a shielding plate 290 located above the material to be rolled between the first upper header 210a and the second upper header 210b may be used. By using such a shielding plate 290, it is possible to accurately shield the scattered cooling water 250 that jumps over the first upper header 210a and the second upper header 210b and falls onto the material 8 to be rolled. In addition, the scattered cooling water 250 that hits the shielding plate 290 is effective because it scatters the scattered cooling water 250 to be scattered in the lateral direction and falls onto the staying cooling water 240 together.

  And also in each cooling device shown to Fig.14 (a), (b), (c), what is necessary is just to adjust the number of the 1st upper header 210a and the 2nd upper header 210b.

  In the description of each cooling device 201 described above, cooling of the lower surface of the material to be rolled 8 is not described. As for the lower surface cooling, there is no problem that the accumulated water 240 originally gets on the material 8 to be rolled and overcooling occurs. Therefore, a general cooling nozzle (spray nozzle, slit nozzle, circular tube nozzle) is used for the lower nozzle 310. You can adopt it. In some cases, the material to be rolled 8 may be cooled only by cooling the upper surface.

  In addition, as the cooling device, those of various embodiments shown in FIGS. 15A, 15B, and 15C may be used.

(Preferred arrangement of near infrared camera)
By the way, the part where the black spot is formed is inferior in mechanical properties such as the elongation and hole expandability of the product steel strip. We have to deal with the situation of delivering to the house.

  In order to prevent such parts of the rolled material with black spots from being delivered to the customer by mistake and to ensure quality assurance, the parts of the rolled material with such black spots It is necessary to be able to make a quality judgment that the image is accurately captured as a locally low temperature portion.

  For this purpose, as shown in FIG. 1B, it is preferable to install a near-infrared camera 25A that can cover and capture the entire width of the material 8 to be rolled on the coiler entrance side.

  On the other hand, based on the measurement result of the near-infrared camera 27A that can photograph the entire width of the hot-rolled metal strip or the entire length of the hot-rolled metal strip installed on the exit side of the first-half zone, In order to prevent the temperature immediately before winding of the hot-rolled metal band from becoming non-uniform, it is preferable to arrange the near infrared camera as shown in FIG. For this, it is preferable to use a near infrared camera arrangement as shown in FIG.

  In addition, the near-infrared camera may, of course, be installed in the middle of the run-out table or on the exit side of the finish rolling mill, or as shown in FIGS. 25 (b) to (d). (FIG. 25C is the same as FIG. 1C).

  Here, the near-infrared camera installed on the inlet side of the coiler is 30 m from the center of the mandrel (not shown) of the coiler 24 on the upstream side in the conveying direction of the material 8 to the upstream side (incoming side) in the conveying direction of the material 8 to be rolled. It is preferable to install in the position within.

  The near-infrared camera installed on the finishing mill exit side is installed at a position within 30 m from the center of the work roll of the final stand of the finishing mill 18 to the downstream side (exit side) in the conveying direction of the material 8 to be rolled. It is preferable to do this.

  The near-infrared camera installed in the middle of the run-out table, if installed, is divided into two zones, the cooling-related equipment 26 between the finishing mill 18 and the coiler 24 of the hot rolling line 100 shown in FIG. It is preferable to install in the middle position between the second and second zone.

(Near-infrared camera specifications, full width shooting method for hot-rolled metal strip)
FIG. 16 shows the relationship between the excision length and the poor flatness (steepness) of the tip, such as a) ear extension and b) medium extension.

  If the portion where the black spot is formed on the material 8 to be rolled is long in the longitudinal direction due to poor flatness (steepness) of the tip portion such as a) ear elongation and b) medium elongation, FIG. As can be seen from the above, it is necessary to lengthen the excision length when excising the entire length of the region including the remarkable portion of the black spot in a post-process such as pickling.

  For this reason, in the longitudinal direction of the material 8 to be rolled, the effect of controlling the flatness in the finish rolling mill 18 does not yet appear. It is preferable to cover and photograph a non-flat portion of the shape of the material 8 to be rolled, which corresponds to the distance from the final stand to the coiler 24, which is several hundreds of meters at the front end or tail end of the material 8 to be rolled.

  Of course, it is also preferable to photograph the entire length of the material 8 to be rolled.

  Each photograph in FIG. 16 is a temporary infrared camera taken on the hot rolling line 100 at a position 1 m upstream of the coiler entry-side thermometer 25 and taken from an overhead view of the finishing mill 18 side. . The target of tensile strength, which is representative of mechanical properties, is 590 MPa, and the target of temperature immediately before winding at the position of the coiler inlet side thermometer 25 is 470 ° C. In the drawing, D denotes a drive (drive side), O denotes an operator side (opposite the drive side), C denotes a center portion, Q denotes a quarter portion, and E denotes an edge portion. The value of the steepness is that at a position of 53 m in the longitudinal direction from the foremost part of the material 8 to be rolled.

  About the tip part and tail end part (length corresponding to the distance from the final stand F7 of the finish rolling mill 18 to the coiler 24) that may have poor flatness of the material 8 to be rolled, at least over its entire length in the longitudinal direction, It is preferable to obtain continuous captured images.

  Of course, it is also preferable to obtain a continuous photographed image over the entire length of the material 8 to be rolled.

  The size per pixel of the near-infrared camera used here is 30 μm long × 30 μm wide, and the number of vertical and horizontal pixel arrangements is 320 × 256 horizontal, as shown in FIG. When the material to be rolled 8 is photographed from directly above as in the case of the main installation, it is converted to the material to be rolled 8 side to be measured, not the near infrared camera side, and the total length is 10 mm × 10 mm wide per pixel. Thus, an area of 3200 mm in the vertical direction (longitudinal direction) × 2560 mm in the horizontal direction (width direction) can be captured in the field of view by one photographing.

  Both vertical and horizontal dimensions per pixel are preferably 10 mm or less in terms of the material to be rolled 8 that is a measurement target. If it is larger than this, the photographed image has a mosaic shape, so that it becomes difficult to understand the outer edge and the planar shape of the black spot.

  On the other hand, the lower limit of the size need not be specified. The above example given as an example is 10 mm or less.

  The width of the material to be rolled that is generally manufactured from the past is 2300 mm at the maximum, and the field of view of this near infrared camera can cover the entire width of all the material to be rolled 8.

  An image captured by the temporary near-infrared camera FIG. 18A shows a case where the image can be normally captured. In the example of the hot rolling line 100, the conveyance speed of the material to be rolled 8 ranges from 120 mpm to 1200 mpm. However, since the vertical (longitudinal direction) has a field of view of 3200 mm, for example, the conveyance speed of the material to be rolled 8 is 1200 mpm. For example, since it takes 3200/1000 ÷ 1200/60 = 0.16 sec to convey 3200 mm, one image is taken every 0.16 sec, and the image is taken from the moment before the tip of the rolled material 8 enters the field of view. The entire length of the material to be rolled 8 is conveyed and the photographing is finished after the moment when the tail end is out of the field of view. If the transport speed is slower, the shooting interval can be increased in inverse proportion to the transport speed.

  By the way, when a near-infrared camera whose shutter speed in one shooting is in the 1/1000 second range and not sufficiently short is used, if the conveyance speed of the material to be rolled 8 is high, as shown in FIG. In addition, the image may be blurred and the black spot may appear large and blur.

  In this embodiment, a near infrared camera having the specifications shown in Table 1 is used. By using a near-infrared camera equipped with a high-speed shutter of the shortest 10 μsec (1 / 100,000 second), it is possible to take a picture so that the image does not flow even when the material to be rolled 8 is fast. .

FIG. 19A shows how much brightness is measured when the shutter speed of the near-infrared camera is changed in various ways. The horizontal axis indicates how much the heat radiation energy (W / mm ² ) is calculated from the temperature of the material 8 to be rolled, and the vertical axis indicates the luminance value ([− ]).

  Although it is a problem on the near-infrared camera side, in the region where the luminance value is less than 8000 ([-]), the influence of noise is large and it becomes difficult to obtain a clear image.

In addition, since the brightness value is measured with a 16-bit signal due to the specifications of this near-infrared camera, the region exceeding 2 ¹⁶ = 65536 ([-]) at the maximum is saturated and cannot be measured. The upper limit was set to 60000 ([-]) for a margin.

  The range between the upper limit and the lower limit described above is a measurable range, and the temperature range corresponding to the range is the measurable temperature range.

  FIG. 19B shows the relationship in an easy-to-understand manner. When the shutter speed is taken on the horizontal axis, the measurable temperature range is shown on the vertical axis. When the shutter speed is shortened, the temperature of the material 8 to be rolled below 300 ° C. becomes impossible to measure from below about 40 μsec, and when the shutter speed is shortened, the measurable temperature range is reduced. It can be seen that the lower limit goes up.

  When the material to be rolled 8 is high-strength steel, the temperature immediately before winding is different depending on the type, but the temperature of the material 8 after cooling by the cooling-related equipment 26 reaches 300 ° C. at the minimum. There is.

  Therefore, if it is attempted to measure the minimum temperature of 300 ° C. regardless of the type of the material to be rolled 8, the shutter speed needs to be 40 μsec or more.

  Therefore, it is preferable to adjust the shutter speed according to the temperature of the material 8 to be rolled.

  That is, for example, when the target temperature immediately before winding of the material to be rolled 8 is a low temperature close to measurable 300 ° C., the shutter speed of the near-infrared camera is set to 40 μsec, for example, to the extent that the image is not blurred. The above-mentioned (in the near-infrared camera used in the present embodiment, the specification is a maximum of 50 μsec: longer than the specification of Table 1), and the target temperature of the rolled material 8 immediately before winding is 450 ° C. to, for example, When the temperature is as high as 750 ° C., it is preferable to reduce the shutter speed of the near-infrared camera to, for example, less than 40 μsec (the shortest is 10 μsec: the same) to ensure the measured temperature range.

  However, since the radiant energy decreases as the temperature of the material 8 to be rolled approaches the measurable lower limit, it goes without saying that it is preferable to increase the shutter speed so as to ensure the measured temperature range. As the temperature of the rolled material 8 approaches the measurable upper limit, it is preferable to shorten the shutter speed as much as possible, because the ability of the light receiving element can be prevented from becoming saturated and the image blurring.

  When adjusting the shutter speed of the near-infrared camera according to the target temperature of the material to be rolled 8, the material to be rolled 8 is not limited to the case where the material to be rolled 8 is high-tensile steel, for example. It is preferable to adjust the shutter speed of the near-infrared camera so as to be determined in advance before actual shooting, depending on the target temperature immediately before winding, which is determined by the type of the image.

  Or it is also preferable to adjust the shutter speed of a near-infrared camera according to the track record of the temperature of the front-end | tip part of the to-be-rolled material 8 measured with the finishing delivery side thermometer 21. FIG.

(Near-infrared camera calibration method)
Next, what a near-infrared camera can measure is brightness. In some cases, the manufacturer of the near-infrared camera may incorporate a logic to convert the brightness into temperature in some way, but when the measurement result does not match the existing spot thermometer, an error of up to 20 ° C will occur. There is a problem.

  Therefore, in order to solve such a problem, the brightness measured with the near-infrared camera and the spot thermometer were measured in advance for the same part of the same heat source outside the hot rolling line, that is, offline. What is obtained when the relationship between the temperature and the temperature of the heat source is changed as a luminance-temperature conversion curve is stored in the control device 50 or the process computer 70, and the hot rolling. There is a method of converting the luminance when the near-infrared camera is installed in a line and photographing the material to be rolled into temperature according to the luminance-temperature conversion curve.

  FIG. 20 shows the result. Further, the scale shown on the right side of FIG. 18A is displayed in relation to the color shade and the temperature. The color is actually a color, but the one that looks whitish as the brightness increases and darker as the brightness decreases is associated with the temperature.

  Alternatively, a near-infrared camera is installed in the hot rolling line to photograph the material to be rolled and measure the temperature, and a spot thermometer at a certain place in the field of view of the near-infrared camera at the place where the near-infrared camera is installed However, after measuring the temperature of the material to be rolled and calibrating the near-infrared camera so that the temperature of the portion of the material to be rolled measured with the spot thermometer matches the temperature measured with the near-infrared camera. There is also a method of photographing the material to be rolled. This can be said to be online calibration.

(Hot rolling line with a near infrared camera capable of photographing the full width of a hot-rolled metal strip)
FIG. 25 (a) shows an example in which a near infrared camera 25A is installed in the form of being attached to the coiler entry-side thermometer 25. However, a coiler that is a spot thermometer at a certain point in the field of view of the near infrared camera. The direction of the coiler inlet side thermometer 25 is adjusted so that the temperature of the material to be rolled can also be measured by the inlet side thermometer 25. FIG. 25 (b) shows an example in which near-infrared cameras 21A and 25A are installed so as to be provided on both the finisher-side thermometer 21 and the coiler inlet-side thermometer 25, and FIG. 25 (c) shows an intermediate temperature. An example in which the near-infrared cameras 27A and 25A are installed so as to be provided in both the total 27 (exit side of the first half zone) and the coiler entrance side thermometer 25, FIG. 25 (d) shows the finish exit side thermometer 21 and An example in which the near-infrared cameras 21A, 27A, and 25A are installed in the form of being attached to the intermediate thermometer 27 (exit side of the first half zone) and the coiler inlet-side thermometer 25 is shown. The direction of the finishing delivery thermometer 21 and the intermediate thermometer 27 which are the meters is also adjusted.

  If the field of view of the spot thermometer is larger than the size of the pixel of the near-infrared camera, and there are multiple near-infrared camera pixels in the field of view of the spot thermometer, the spot thermometer It is preferable to obtain a brightness-temperature conversion curve or calibrate the near-infrared camera so that the temperature measured at the pixel and the temperature measured at the pixel match, but the average values match. For example, other methods may be used.

(Full width shooting result recording method, quality judgment method, quality judgment result recording method of hot rolled metal strip)
Now, the story changes, and how the quality is determined based on the planar (two-dimensional) temperature distribution of the material 8 to be rolled measured with a near infrared camera. An example of taking a picture and measuring the temperature will be described below.

  First, the overall flow will be described with reference to each step in FIG.

  First, when the conveyance speed of the material to be rolled 8 is 1200 mpm, the temperature distribution data of the full width of the entire length is measured every 3200 mm in the conveyance direction, that is, the longitudinal direction of the material 8 to be rolled, by photographing once every 0.16 sec. I told you to do.

  When one piece of the material to be rolled 8 is photographed up to its tail end, here, for ease of later processing, the temperature distribution data of the full width of the whole length of the material to be rolled 8 is as in the examples described later. Temporarily stored in a recording medium such as a memory attached to a computer such as a personal computer, and re-edited into temperature distribution data divided every predetermined length, for example, every 4 m (4000 mm) in the longitudinal direction of the material 8 (step 110). ).

  The result is stored in a recording medium such as a hard disk attached to a computer such as a personal computer (step 120).

  The data may be one or more at a time. Again, it is read out and temporarily stored in a recording medium such as a memory attached to the computer such as the personal computer (step 130).

  Then, in the one structural unit or in one screen, it is determined whether or not all the pixels are out of the temperature tolerance, and the pixels exceeding the upper limit value of the temperature tolerance (temperature upper limit threshold value), Pixels that are below the lower limit of the temperature tolerance (temperature lower limit threshold) are temporarily stored together with the plane (two-dimensional) coordinates of the pixel (which may be representative values or vertical and horizontal ranges), and the plane outside the temperature tolerance (two-dimensional) A distribution is created (step 150).

  Further, for each individual material 8 to be rolled, various statistical values of defective portions of quality out of the temperature tolerance are calculated for every fixed length, that is, for each of the above-mentioned one structural unit (step) 160). Details thereof will be described later.

  Further, the quality defective portion of the material 8 to be rolled out of the temperature tolerance is determined from each of the various statistical values, for example, every 1 m, and, for example, a hexadecimal display of the quality determination result as shown in FIG. And set as bit information over the entire length (step 170). Details of this will also be described later.

  Finally, regarding the poor quality portion of the material 8 to be rolled out of the temperature tolerance, the starting position from the tip of the material 8 to be rolled and its length are determined, and each material to be rolled 8 is linked to each other. The data is stored in a recording medium such as a hard disk attached to the computer (step 180).

  The above description of how the quality determination is performed and the overall flow of the processing are as described above. Details of the processing of (Step 160) and (Step 170) described later are as follows. This will be described below.

  The process of calculating the statistical value in (Step 160) is as follows.

Examples of statistical values to be calculated include the following.
(1) Out-of-tolerance area ratio As shown in FIG. 23 (a), the ratio of the area of the poor quality portion of the material 8 out of the temperature tolerance that occupies the area of the material 8 viewed from above is the tolerance. It is a detached area ratio (%).

The calculation formula is as follows.
Tolerance out-of-tolerance ratio = Sigma out of tolerance area S _i / (region length × rolled material width) × 100 (%)
... (8)
(2) Out-of-tolerance length ratio As shown in FIG. 23 (b), in the longitudinal direction of the quality defect portion of the rolled material 8 out of the temperature tolerance, which occupies the length of the region viewed from above the rolled material 8. The length ratio is the out-of-tolerance length ratio (%). If there is a region that wraps in the longitudinal direction, the wrapping region is not counted twice, but is considered as one region, and its length is calculated and calculated (L ₃ in FIG. 23B).

The calculation formula is as follows.
Tolerance length ratio = Σ Tolerance length L _i / Area length (9)
(3) Average number out of tolerance As shown in FIG. 23 (c), the number of screens N (N = 4 in the present embodiment) per display area of the quality defect portion of the rolled material 8 out of the temperature tolerance. The number is an average number out of tolerance.

The calculation formula is as follows.
Average number of tolerance deviation = Number of tolerance deviation points / Number of screens N (Piece / Constant length 4m pitch)
... (10)
(4) Average area of out-of-tolerance locations / pieces As shown in FIG. 23 (d), the sum of the areas of poor quality parts of the rolled material 8 out of temperature tolerance divided by the number of the same parts, The average area / piece of out-of-tolerance locations.

The calculation formula is as follows.
Average area of out-of-tolerance locations / piece = Σ Tolerance out-of-place area S _i / Number of out-of-tolerance locations
(11)
On the other hand, the process of determining the defective portion and determining the length in (Step 170) is as follows. In the present embodiment, (1) to (3) are determined for every 4 m pitch of the material to be rolled, and (4) and (5) are considered to require particularly detailed determination, and for each 1 m of material to be rolled. Judgment is made.
(1) Judgment based on out-of-tolerance area ratio When the result of the calculation by the above-described equation (8) (region length = 4 m in this embodiment) is equal to or greater than a certain threshold value _SNG1 , the structural unit of the material to be rolled 4m The result of the quality determination is determined to be rejected (NG).
(2) Tolerance out of determination described above by length ratio (9) Results of Computational (region in this embodiment the length = 4m) is, in the case of more than a threshold L _NG, structure of the material to be rolled 4m About a unit, it determines with the result of quality determination being disqualified (NG).
(3) Judgment based on average number of out-of-tolerance When the result of calculation according to the above-mentioned equation (10) (in this embodiment, the number of screens N = 4) is a certain threshold value _NNG or more, the constituent unit of the material to be rolled 4m The result of the quality determination is determined to be rejected (NG).
(4) Determination by area per out-of-tolerance location When the area S _{i of} out-of-tolerance location is at least one threshold S _NG2 or more, as shown in FIG. The result of quality determination is determined to be rejected (NG) for each material 1 m. (Be careful because it is different from the above-mentioned equation (11). However, since what is used in the calculation process of the above-mentioned equation (11) is used for determination, it is not so difficult.)
(5) Judgment based on longitudinal and width direction dimensions for each out-of-tolerance location There is at least one threshold value L _{NG that} has a longitudinal direction dimension in an out-of-tolerance location, or a threshold value that has a width-direction size in an out-of-tolerance location If there is at least one _WNG or more, as shown in FIG. 24 (b), the quality judgment result is judged to be rejected (NG) for each rolled material 1m. .

By the way, in the present embodiment described above, the temperature upper limit threshold, the temperature lower limit threshold, the tolerance threshold area threshold S _NG1 , the tolerance dimension longitudinal dimension threshold L _NG , and the tolerance dimension width dimension threshold. W _NG , threshold value N _NG of the number of out-of-tolerance locations, area threshold value S _NG2 per out-of-tolerance location, and the like are stored in the process computer 70 for each type and size of the material 8 to be rolled. If necessary, it may be transmitted to a business computer 90 or a personal computer, or may be transmitted to a near-infrared camera via the control device 50.

  Now, although the story changes a little, in the case of batch rolling, as described above, the tip portion and the tail end portion of the material 8 to be rolled can have uneven portions. Of these, dozens of meters will always be out of tolerance, so they should be cut out in a later process, and instead, the same material should not be subject to quality judgment. Measures such as avoiding the complexity of becoming may be taken.

  Similarly, the cooling water riding on the upper surface of the material to be rolled 8 flows down from both edges in the width direction, so that both edges in the width direction of the material to be rolled 8 are cooled more strongly than the center in the width direction and are locally low in temperature. Since parts are formed, these parts may not be subjected to quality determination.

  Because of the above cases, the process computer calculates the length of the material to be rolled at the tip, the length of the material to be rolled at the tail end, the width / width of the material to be rolled at the edge, and the like for each type and size of the material 8 to be rolled. It is also preferable that the data is stored in 70 or the like, and transmitted to the business computer 90 or a personal computer, or transmitted to the near-infrared camera via the control device 50 as necessary.

Furthermore, because of the outlier removal and noise reduction, the upper temperature limit threshold, below the temperature lower limit threshold, temperature upper filter values, such as temperature lower filter value, also, the threshold L _NG longitudinal dimension of the tolerance off point upper, above the threshold W _NG in the width direction dimension of the portion out tolerances of the filter value of the longitudinal dimension of the portion out tolerances, etc. filter value of the width dimension of the portion out tolerances, is stored in such a process computer 70 in If necessary, it may be transmitted to the business computer 90 or a personal computer, or may be transmitted to the near-infrared camera via the control device 50.

  The overall flow of how to perform quality determination based on the planar (two-dimensional) temperature distribution of the material to be rolled 8 measured with a near-infrared camera, and processing of some steps However, the description of the example in the present embodiment is finished. However, the present embodiment described above is merely an example, and the specific logic of the quality determination is limited to the present embodiment described above. is not.

(Reference Example 1)
(Computer system)
FIG. 25A shows a part extracted from the finishing mill 18 of the hot rolling line 100 shown in FIG. 31 described above. As shown in FIG. 25 (a), a near-infrared camera 25A was installed in the form of being attached to the coiler entry-side thermometer 25. The distance between them is only 1 m.

  The plane (two-dimensional) temperature data of the rolled material 8 measured by the near-infrared camera 25A is sent to the dedicated personal computer 251 and subjected to image processing. For the poor quality portion of the rolled material 8 that is out of the temperature tolerance, After the starting position from the tip of the material 8 to be rolled and its length are determined, the plane (two-dimensional) of the material 8 to be rolled, including the results of the quality determination for each fixed length (4 m) and 1 m as described above. ) In addition to the temperature data, all the data appearing above are linked to each rolled material 8 as a result of the quality judgment of the hot-rolled metal strip, and are similarly linked to each rolled material 8 If the identification data called No is recorded in the key and the coil No. is further input, it passes through the local LAN 252 and is located in a plurality of other locations, for example, the office of the manufacturing department or the office of the quality control department Etc. The computer 253 can remotely copy the planar (two-dimensional) temperature data after the image processing, and reproduce the temperature data after the image processing on the screen of the personal computer 253 in each office. In addition, the temperature data after the image processing can be analyzed or processed. Of course, it can also be used for quality assurance in product delivery to consumers. This is because if there is a poor quality part, it is possible to take a countermeasure such as adding a purification process such as pickling or skin pass, and instructing artificially to remove the poor quality part.

  Although it depends on the length of one rolled material 8, the data has a capacity of about 20 to 40 MB. Therefore, even with a storage capacity such as a hard disk of a personal computer, data for several hundred pieces of rolled material can be used. Can be recorded. If you focus on high-strength steel, you can practically record several months of data. It goes without saying that recording can be done semipermanently by replacing the hard disk.

  As described above, even when the storage capacity is about the same as that of a personal computer, hot rolling is used to record the result of quality determination using a near-infrared camera capable of photographing the entire width of a hot-rolled metal strip that is rolled in a hot rolling line. A computer system 900 for recording the quality determination result of the metal strip can be constructed.

(Reference Example 2)
FIG. 25 (b) shows an example in which near-infrared cameras 21A and 25A are installed so as to be provided on both the finisher-side thermometer 21 and the coiler inlet-side thermometer 25.

  It is the same as that in the first embodiment after the route where the planar (two-dimensional) temperature data of the material 8 to be rolled measured by the near-infrared cameras 21A and 25A is transmitted to the dedicated personal computer 251 and later.

  Temperature data after image processing is analyzed and processed, and can be used for quality assurance in product delivery to customers, as well as temperature data measured by the near infrared camera 21A attached to the finishing-side thermometer 21 Based on the above, the feed-forward control, such as weakening the cooling method by the cooling-related equipment 26, is performed on the portion of the rolled material 8 where the black spot is present, so that the temperature immediately before winding the rolled material 8 is possible. The quality of the whole length of the material 8 to be rolled is to be as good as possible.

(Reference Example 3)
FIG. 25C shows an example in which near-infrared cameras 27A and 25A are installed so as to be attached to both the intermediate thermometer 27 (exit side of the first half zone) and the coiler inlet-side thermometer 25.

  The route after the plane (two-dimensional) temperature data of the rolled material 8 measured by the near-infrared cameras 27A and 25A is transmitted to the dedicated personal computer 251 and later is the same as in the first and second embodiments.

  Cooling-related equipment based on the temperature data measured by the finishing thermometer 21 as well as being used for quality assurance in product delivery to customers after analyzing and processing the temperature data after image processing 26, feed-forward control for cooling the material 8 to be rolled is performed at a portion upstream of the intermediate thermometer 27 (exit side of the first half zone) or further downstream, but the intermediate thermometer 27 Based on the temperature data measured by the near-infrared camera 27A attached to the center, the portion with the black spot of the material 8 to be rolled is cooled by the portion downstream of the intermediate thermometer 27 in the cooling related equipment 26. In addition to performing feed-forward control such as weakening the method, the portion of the material 8 to be rolled that has a black spot upstream of the intermediate thermometer 27 in the cooling-related equipment 26 By also performing feedback control such as weakening the cooling method by this part, the temperature immediately before winding the rolled material 8 is more assured as uniform as possible, and the rolled material 8 is made as much as possible. It is intended to pass the quality for the full length of the whole.

(Example)
(Cooling control method for hot-rolled metal strip)
As in the third embodiment, as shown in FIG. 25 (c), a hot rolling line provided with near-infrared cameras 27A and 25A in the form of being attached to both the intermediate thermometer 27 and the coiler inlet-side thermometer 25. The result of actually manufacturing a high-strength steel at 100 and applying the method for cooling a hot-rolled metal strip according to the present embodiment will be described below.

  This high-tensile steel has a product size of 3.2 mm thickness × 900 mm width, and the target temperature immediately before winding is 350 ° C.

  The target hot-rolled metal strip temperature at the completion of finish rolling is 840 ° C., cooled to 550 ° C. in the first half zone and 400 ° C. in the second half zone, and then wound by the coiler 24.

  Here, from the viewpoint of securing a desired material, the allowable range of the temperature immediately before winding is a coiler entry-side thermometer 25 that is a radiation thermometer (spot thermometer) installed at the center of the width of the hot rolling line 100. Measured and within 60 ° C over the entire length of the hot rolled metal strip.

The structure of the cooling device in the first half zone is a circular tube laminar nozzle on the upper surface side and a spray nozzle on the lower surface side, each having a water density of 1.0 m ³ / m ² / min.

  In addition, the structure of the cooling device in the latter half zone is adjusted by changing the number of headers installed, the water injection flow rate from each cooling device with water volume density of 0.2 m3 / m2 on both upper and lower surfaces.

  The specifications of the near infrared camera are shown in Table 1. The resolution is determined by the number of pixels of the near infrared camera, the installation height of the near infrared camera from the pass line, the lens magnification of the near infrared camera, and the like.

  Here, with the goal of capturing a black spot of φ100 mm, the number of pixels of the near infrared camera, the installation height of the near infrared camera from the pass line, the lens magnification, and the like were determined.

  The shutter speed needs to be determined according to the transport speed. Here, the shutter speed is determined so that the moving amount during the exposure time is within 0.3 mm at the conveyance speed of 1500 mpm.

  Further, a radiation thermometer is installed in the center of the width of the hot rolling line 100 between the finishing mill and the first half zone, on the exit side of the first half zone, and on the exit side of the second half zone (finishing side thermometer). 21, intermediate thermometer 27, coiler inlet side thermometer 25), and these thermometers can measure the temperature distribution in the longitudinal direction of the hot-rolled metal strip.

  Summarized results on the deviation defined by the average of the temperature just before winding in the longitudinal direction of the hot rolled metal strip and the temperature (maximum value-minimum value) just before winding in the longitudinal direction of the hot rolled metal strip It shows in Table 2.

  In Table 2, the experimental conditions and the average temperature immediately before winding in the longitudinal direction of the hot-rolled metal strip after cooling and the winding in the longitudinal direction of the hot-rolled metal strip are shown in Table 2. The deviation defined by (maximum value-minimum value) of the temperature immediately before taking is summarized and described.

Example 1
The threshold ΔTL was set to 30.0 ° C. There is a low-temperature part below the threshold in the range of 5 m in the length direction from the front end of the hot-rolled metal strip, and this embodiment is used by using the near-infrared camera 27A provided on the exit side of the first half zone. By the cooling control method for the hot-rolled metal strip, the number of nozzles for injecting the cooling water in the first half zone was adjusted by feedback control until it was within the threshold range.

  As a result, the number of nozzles for injecting cooling water is reduced from 5 to 79 from the initial setting of 84 when the cutting edge of the hot-rolled metal band passes, and the average temperature of the hot-rolled metal band measured on the outlet side of the first half zone Rose 19 ° C from 532 ° C to 551 ° C.

  At the same time, the number of nozzles for injecting cooling water in the latter half zone increased by 8 from the initial setting of 67 when the leading edge of the hot-rolled metal band passes to 75.

  FIG. 26 (a) shows a chart of the temperature just before winding measured by a coiler inlet side thermometer 25 which is a radiation thermometer (spot thermometer) installed in the center of the width of the hot rolling line 100. The temperature immediately before winding of the metal strip in the longitudinal direction was 404 ° C. on average, which was almost as intended. In addition, the adjustment of the number of nozzles for injecting cooling water and the adjustment of the water injection flow rate by the method for cooling the hot-rolled metal strip according to the present embodiment are located at a position of 100 m in the longitudinal direction from the forefront of the hot-rolled metal strip The temperature deviation just before the winding in the longitudinal direction, including the following, was also kept as small as 53 ° C.

(Example 2)
Applying the hot-rolled metal strip cooling control method according to the present embodiment to the hot-rolled metal strip used in Example 1, that is, feedback control to the cooling method in the first half zone, the next hot-rolled metal strip is used. Since the metal band was also the same material and dimensions, based on the measurement result of the temperature distribution in one image taken in the field of view of the near-infrared camera of the hot-rolled metal band used in Example 1, An average temperature of the hot-rolled metal strip and a deviation obtained by subtracting a minimum value of the temperature in the one image from the average temperature are calculated, and the deviation is calculated in the hot-rolled metal strip by the feedback control. The width of the hot rolling line on the outlet side of the first half zone of the hot-rolled metal strip after the time when the temperature of the rolled metal strip becomes less than a threshold value ΔTL for determining that the temperature in the width direction has become uneven. The average value in the longitudinal direction of the temperature measurement result at the center The next hot rolled metal strip, in the exit side of the first half zone, described above, as the temperature set point of the width center of the hot rolling line, the above-mentioned, was cooling control for the next hot rolled metal strip.

  FIG. 26B shows a chart of the temperature just before winding measured in the same manner as in Example 1.

  The temperature immediately before winding in the longitudinal direction of the hot-rolled metal strip after cooling was 402 ° C. on average, which was almost as intended. Moreover, the temperature deviation just before winding in the longitudinal direction could be kept as small as 51 ° C.

(Comparative Example 1)
The near-infrared camera 27A provided on the exit side of the first half zone was not used, and feedback control by the cooling control method for the hot-rolled metal strip according to the present embodiment was not performed.

  FIG. 26 (c) shows a chart of the temperature immediately before winding measured in the same manner as in Example 1 and Example 2.

  The temperature immediately before winding in the longitudinal direction of the hot-rolled metal strip after cooling is 380 ° C. on average, which is not the target, and the temperature deviation just before winding in the longitudinal direction of the hot-rolled metal strip is as large as 95 ° C. It is had.

  It can be seen that the temperature deviation in the longitudinal direction of the hot-rolled metal strip is already 60 ° C. on the exit side of the first half zone, and this has expanded to 95 ° C. on the exit side of the second half zone.

  Although the transition boiling start temperature was lowered by decreasing the water density, the transition from film boiling to transition boiling could not be suppressed, so the temperature after cooling was considered to have varied.

(Comparative Example 2)
Instead of the near-infrared camera 27A, a planar (two-dimensional) temperature distribution was measured using a scanning radiation thermometer, and feedback control similar to that in the example was performed.

  FIG. 26 (d) shows a chart of the temperature immediately before winding measured in the same manner as in Example 1, Example 2 and Comparative Example 1, but a black spot with a diameter of 50 to 100 mm that can be captured by a near-infrared camera, Since the scanning radiation thermometer cannot be completely captured, even if similar feedback control is performed, the temperature deviation just before winding in the longitudinal direction of the hot-rolled metal strip has increased to 67 ° C.

(Reference Example 4)
As in the above embodiment, as shown in FIG. 25 (c), the hot rolling line 100 in which the near infrared cameras 27A and 25A are installed so as to be provided in both the intermediate thermometer 27 and the coiler inlet side thermometer 25. In the following, the results of actually manufacturing high-strength steel and applying the method for cooling a hot-rolled metal strip according to the present embodiment will be described.

  This high-tensile steel has a product size of 3.2 mm thickness × 900 mm width, and the target temperature immediately before winding is 350 ° C.

  The target hot-rolled metal strip temperature at the completion of finish rolling is 840 ° C., cooled to 550 ° C. in the first half zone and 350 ° C. in the second half zone, and then wound by the coiler 24.

  Here, from the viewpoint of securing a desired material, the allowable range of the temperature immediately before winding is a coiler entry-side thermometer 25 that is a radiation thermometer (spot thermometer) installed at the center of the width of the hot rolling line 100. Measured and within 60 ° C over the entire length of the hot rolled metal strip.

The structure of the cooling device in the first half zone is a circular tube laminar nozzle on the upper surface side and a spray nozzle on the lower surface side, each having a water density of 1.0 m ³ / m ² / min.

Further, the cooling device in the latter half zone is provided with a circular tube laminar nozzle excellent in straightness with a water density of 2.0 m ³ / m ² / min on both the upper surface and the lower surface.

  The length of the cooling device in the transport direction is 75 m for the cooling device in the first half zone and 10 m for the cooling device in the second half zone.

  A plurality of nozzles are installed in the transport direction A, and can be individually turned on and off.

  The flow rate of water injected from each cooling device is adjusted by changing the number of nozzles installed.

  The specifications of the near infrared camera are shown in Table 1. The resolution is determined by the number of pixels of the near infrared camera, the installation height of the near infrared camera from the pass line, the lens magnification of the near infrared camera, and the like.

  Here, with the goal of capturing a black spot of φ100 mm, the number of pixels of the near infrared camera, the installation height of the near infrared camera from the pass line, the lens magnification, and the like were determined.

  The shutter speed needs to be determined according to the transport speed. Here, the shutter speed is determined so that the moving amount during the exposure time is within 0.3 mm at the conveyance speed of 1500 mpm.

  Further, a radiation thermometer is installed in the center of the width of the hot rolling line 100 between the finishing mill and the first half zone, on the exit side of the first half zone, and on the exit side of the second half zone (finishing side thermometer). 21, intermediate thermometer 27, coiler inlet side thermometer 25), and these thermometers can measure the temperature distribution in the longitudinal direction of the hot-rolled metal strip.

  Summarized results on the deviation defined by the average of the temperature just before winding in the longitudinal direction of the hot rolled metal strip and the temperature (maximum value-minimum value) just before winding in the longitudinal direction of the hot rolled metal strip Table 3 shows.

  In Table 3, the experimental conditions and the average temperature immediately before winding in the longitudinal direction of the hot-rolled metal strip after cooling and the winding in the longitudinal direction of the hot-rolled metal strip are shown in Table 3. The deviation defined by (maximum value-minimum value) of the temperature immediately before taking is summarized and described.

(Example)
The threshold ΔTL was set to 33.8 ° C. There is a low-temperature part below the threshold in the range of 5 m in the length direction from the front end of the hot-rolled metal strip, and this embodiment is used by using the near-infrared camera 27A provided on the exit side of the first half zone. By the cooling control method for the hot-rolled metal strip, the number of nozzles for injecting the cooling water in the first half zone was adjusted by feedback control until it was within the threshold range.

  As a result, the number of nozzles for injecting cooling water is reduced from 5 to 79 from the initial setting of 84 when the cutting edge of the hot-rolled metal band passes, and the average temperature of the hot-rolled metal band measured on the outlet side of the first half zone Rose 19 ° C from 532 ° C to 551 ° C.

  At the same time, the number of nozzles for injecting cooling water in the latter half zone increased by two from 34, which was the initial setting when the leading edge of the hot-rolled metal strip passes.

  FIG. 27 (a) shows a chart of the temperature just before winding measured by a coiler inlet side thermometer 25 which is a radiation thermometer (spot thermometer) installed in the center of the width of the hot rolling line 100. The temperature immediately before winding the metal strip in the longitudinal direction was 354 ° C. on average, which was almost as intended. In addition, the adjustment of the number of nozzles for injecting cooling water and the adjustment of the water injection flow rate by the method for cooling the hot-rolled metal strip according to the present embodiment are located at a position of 100 m in the longitudinal direction from the forefront of the hot-rolled metal strip The temperature deviation just before the winding in the longitudinal direction, including the following, was also kept as small as 53 ° C.

(Comparative Example 1)
The near-infrared camera 27A provided on the exit side of the first half zone was not used, and feedback control by the cooling control method for the hot-rolled metal strip according to the present embodiment was not performed.

FIG. 27B shows a chart of the temperature just before winding measured in the same manner as in the example. As the water amount density of 0.3 m ³ / m less than ² / min, and cooled to 550 ° C. at a cooling water temperature of 30 ° C. in the first half zone, as cooling by spraying both upper and lower surfaces in the second half zone, water density 0.2 m ³ This is an example of cooling to 350 ° C., which is the temperature just before the target winding, with cooling water at a temperature of 30 ° C./m ² / min.

  The temperature immediately before winding in the longitudinal direction of the hot-rolled metal strip after cooling was 359 ° C. on average, which was almost the target, but the temperature deviation immediately before winding in the longitudinal direction of the hot-rolled metal strip was 90 It has grown to ℃.

  Although the transition boiling start temperature was lowered by reducing the water density, the transition from film boiling to transition boiling could not be completely suppressed, so the temperature after cooling was considered to have varied.

(Comparative Example 2)
Instead of the near-infrared camera 27A, a planar (two-dimensional) temperature distribution was measured using a scanning radiation thermometer, and feedback control similar to that in the example was performed.

  FIG. 27 (c) shows a chart of the temperature immediately before winding measured in the same manner as in Example and Comparative Example 1, but a black spot with a diameter of 50-100 mm that can be captured by a near-infrared camera is scanned with a scanning radiation thermometer. Therefore, even if the same feedback control is performed, the temperature deviation just before winding in the longitudinal direction of the hot-rolled metal strip has become as large as 67 ° C.

(Reference Example 5)
FIG. 25 (d) shows an example in which near-infrared cameras 21A, 27A, and 25A are installed in the form of being provided side by side with a finisher-side thermometer 21, an intermediate thermometer 27, and a coiler inlet-side thermometer 25.

  In the case of FIG. 25 (c), instead of the finishing delivery thermometer 21, the same control as in Reference Example 3 is performed based on the temperature data measured by the near-infrared camera 21A, thereby ensuring more certainty. In addition, the temperature immediately before winding of the material to be rolled 8 is made as uniform as possible, and the quality of the whole length of the material 8 to be rolled is to be as good as possible.

(Reference Example 6)
(Vidicon system, removal of defective parts of hot-rolled metal strip in the post process)
As shown in FIG. 28, the temperature data measured by the near-infrared camera is taken in via the control device 50, and the role of the dedicated personal computer 251 in FIGS. 25 (a) to 25 (d) is played by the process computer 70 or the business computer 90. In the business computer 90, identification data called a coil No associated with each material to be rolled 8 is recorded as a key.

  In addition to the above method, a dedicated personal computer 251 (not shown) is provided between the near-infrared camera and the control device 50, between the control device 50 and the process computer 70, or between the process computer 70 and the business computer 90. The temperature data after interpolating and image processing by the dedicated personal computer 251 is sent to the business computer 90. Further, in the business computer 90, the identification data called coil No. associated with each rolled material 8 is used as a key. The temperature data after image processing may be recorded.

  Instead of the in-house LAN 252 in FIG. 25, a network that connects the business computers 90 for each line via a dedicated line is formed, and a terminal or personal computer connected to the business computer 90 for each line, or directly to the network. If the coil No. is input from the connected terminal or personal computer, the image can be processed remotely at remote locations such as offices in the manufacturing department and offices in the quality control department. The two-dimensional temperature data can be copied, and the temperature data after image processing can be reproduced on the terminal or PC screen of each office, and the temperature after image processing. Data can also be analyzed or processed. Of course, it can also be used for quality assurance in product delivery to consumers.

  When it is automatically determined that there is a poor quality part, a refining process such as a pickling line 200 having an inline skin pass 30 is added as a subsequent process of the hot rolling process according to a command from the business computer 90. This is because it is possible to take measures such as automatically instructing to cut off the defective portion with the shear 5.

  When poor quality parts are concentrated in the range of 30m from the foremost part of the material 8 to be rolled, 30m is cut off and the rolled material after the bad quality part is cut off at the tail end of the previous material to be rolled. The tip of the material 8 is welded by the welding machine 6 and is continuously passed through the pickling line 200.

  However, for example, when there is a poor quality part in the range of 30 to 40 m and the range of 100 to 120 m from the cutting edge of the material 8 to be rolled, the range of 30 to 40 m and the range of 100 to 120 m are excised. So, a healthy part for 60m is made in the 40-100m part, but it is an order from the customer where the welded part may be mixed, or the welded part should not be mixed, but a small weight for 60m However, if it is an order from an okay customer or an order that eventually becomes a cut plate, the 60 m healthy portion is welded to the front and rear ends of the material to be rolled by the welding machine 6. Then, the pickling line 200 is continuously passed.

  If it is an order from a customer who should not have a welded portion and should not have a small weight of 60m, the entire range of 30 to 100m should be excised and the tail of the previous rolled material At the end, the tip of the material to be rolled 8 after the poor quality portion is excised is welded by the welding machine 6 and continuously passed through the pickling line 200.

  The same applies to the tail end of the material 8 to be rolled.

  When automatically instructing to cut out the poor quality portion with the shear 5, the cutting command, where to cut in the longitudinal direction of the material to be rolled, the longitudinal position (cutting start position) and the cutting length are used as commands. Make output.

  The business computer 90, in addition to the attribute data such as the order material, order thickness, order width, etc. from the customer of each material 8 to be rolled, for example, the full length thickness distribution in the hot rolling line 100 and the full width measured with a near infrared camera. Various huge production record data such as temperature distribution are recorded in association with each material 8 to be rolled. In addition to the hot rolling line 100, the entire picking line 200 and other manufacturing processes such as cold rolling (not shown) are also included here. In addition to instructing and managing the passing process through the company, it also manages manufacturing and quality results.

  Including these business functions, including business computer 90, its computer program, attached recording device and recording medium, and terminals and personal computers connected thereto, and man-machine data interface functions such as its screen display function, A computer system is called a vidicon system.

  FIG. 28 shows an outline of a vidicon system 901 that includes the hot rolling line 100 and other manufacturing processes, as well as the passing process instruction and management, and the manufacturing and quality results management.

  In the example of FIG. 28, the business computer 90 is provided separately for a hot rolling line, for a cold rolling line, for a pickling line, for other lines, etc., but the way of dividing is limited to the above example. Alternatively, it may be integrated into one computer.

Moreover, in FIG. 28, although the case where the form of FIG. 25 (a) is followed is mentioned as an example as a form which installs a near-infrared camera in the hot rolling line 100, FIG.25 (b)-(d). An example of the case of following various forms is also possible.
(Method for producing hot-rolled metal strip)
Below, the effect by implementation of this invention is demonstrated.

  FIG. 29 shows data obtained by continuously measuring the temperature at the coiler entrance side only in the center of the hot rolling line of the material 8 to be rolled, in the longitudinal direction. Since the material to be rolled was moderately elongated, the longitudinal distribution of the flatness (steepness) at the center of the width of the material to be rolled and the longitudinal distribution of the temperature of the material to be rolled showed a correlation. It can be seen that a part having a low temperature of the material to be rolled is locally formed in a part having a poor flatness within a range of 20 m from the most advanced part. Actually, the part surrounded by ○ was cut out, but when it was pressed under the same conditions as the customer as a test, a crack occurred.

  In addition, before installing the near infrared camera on the coiler entry side, it was necessary to determine the poor quality part based on the temperature measurement result by the coiler entry side thermometer 25, but the vertical axis in FIG. The value obtained by subtracting the length of the portion determined to be a defective quality when the temperature is measured by the coiler inlet side thermometer 25 from the length of the portion determined to be a defective quality when the temperature is measured is 10 m or more. It shows the ratio of the number of the material to be rolled. Before the near-infrared camera was installed on the entrance side of the coiler, about 25.5% of the material to be rolled, the material exceeding the temperature upper threshold or the temperature lowering below the temperature lower threshold was judged to be small. (After installing a near-infrared camera on the inlet side of the coiler, the ratio is naturally 0%.)

  Using a near-infrared camera installed on the coiler entrance side of the hot rolling line, film the entire width of the hot-rolled metal strip, measure its temperature distribution, and control the cooling method based on the measurement results. By doing so, it will be possible to properly guarantee the quality of products delivered to consumers.

Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention A diagram showing the relationship between the ablation length and the poor flatness (steepness) of the tip, such as a) ear extension and b) medium extension Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Schematic for explaining one embodiment for carrying out the present invention Diagram for explaining another embodiment for carrying out the present invention Diagram for explaining the effect of the present invention Graph for explaining the effect of the present invention Diagram for explaining an example of a conventional hot rolling line Diagram for explaining the problems of the prior art Diagram for comparing film boiling and nucleate boiling Diagram for explaining the prior art Diagram for explaining the problems of the prior art Diagram for explaining the prior art

Explanation of symbols

5 Shear 6 Welding machine 8 Rolled material
10 Heating furnace
12 Rough rolling mill
13 Table roller
135 Edger Roll
14 Cropshire
15 Finishing-side thermometer
18 Finishing mill
19 Work roll
20 Backup roll
21 Finishing side thermometer
21A near infrared camera
22 Finishing side thickness gauge
23 Runout Table
24 coiler
25 Coiler inlet side thermometer
25A near infrared camera
251 PC
252 Local LAN
253 PC at each office
26 Cooling related equipment
27 Intermediate thermometer
27A near infrared camera
28 Majoring roll
29 Speedometer
30 Inline skin pass
50 Control unit
70 process computer
90 Business computer
100 hot rolling line
200 pickling line
201 Cooling device
210 Upper header unit
210a First upper header
210b Second upper header
210c Intermediate header
220a First upper nozzle group
220b Second upper nozzle group
230a Rod cooling water
230b Rod cooling water
240 Stagnant cooling water
250 splash cooling water
260a Shield plate
260b Shield plate
270a cylinder
270b cylinder
280a Screening curtain
280b Screening curtain
290 Shield plate
300 ON-OFF mechanism
310 Lower nozzle
900 computer system
901 vidicon system A transport direction B width direction

Claims (4)

The cooling-related equipment between the finish rolling mill and the coiler in the hot rolling line is divided into a first half zone and a second half zone. In the first half zone, the water density per front and back single side is 0.7 m ³ / m ² / min or more. Supply cooling water of ² m ³ / m ² / min or less, and supply water with a water density of 0.05 m ³ / m ² / min or more and 0.3 m ³ / m ² / min or less per front and back side surfaces in the latter half zone. Then, the temperature of the hot-rolled metal strip immediately before winding is controlled, and in the first half zone, in addition to that, the full width of the hot-rolled metal strip installed on the exit side of the first half zone Based on the result of temperature measurement by a near-infrared camera, which can be photographed for a part of the length, feedback to the temperature control of the hot-rolled metal strip in the first half zone, The method for controlling cooling of a hot-rolled metal strip, comprising controlling the temperature of the hot-rolled metal strip. In order to compensate for the temperature increase immediately before winding of the hot-rolled metal strip due to the feedback, the hot-rolling immediately before winding is fed forward to control the temperature of the hot-rolled metal strip in the latter half zone. The method for controlling cooling of a hot-rolled metal strip according to claim 1, wherein the temperature of the metal strip is controlled. When the cooling control method for a hot-rolled metal strip according to claim 1 is applied to a hot-rolled metal strip, and the next hot-rolled metal strip has the same material and dimensions, Based on the result of temperature measurement in one image taken in the field of view of the near-infrared camera, the average temperature of the hot-rolled metal strip and the minimum value of the temperature in the one image are subtracted from the average temperature. After the time when the deviation becomes less than a threshold value ΔTL for determining that the temperature of the hot-rolled metal strip becomes non-uniform in the width direction by the feedback. The average value in the longitudinal direction of the measurement result of the temperature at the center of the width of the hot rolling line at the outlet side of the first half zone of the hot rolled metal band in the first half zone of the next hot rolled metal band. Target temperature at the center of the width of the hot rolling line as described above As the the cooling control method for the hot-rolled metal strip, characterized in that to perform the cooling control for the next hot rolled metal strip. A method for producing a hot-rolled metal strip using any one of claims 1 to 3.