JP5577580B2 - Thick steel plate quality assurance system - Google Patents

Description

  The present invention relates to a material guarantee system for thick steel plates, and more particularly to a material guarantee system suitable for material guarantee over the entire upper surface or lower surface, or the entire upper surface and lower surface of a thick steel plate that is subjected to controlled rolling or accelerated cooling.

  For TMCP technology to improve the strength and toughness of thick steel plates by refining the crystal grain size in the material structure, strictly control the inlet side temperature, outlet side temperature, inlet side temperature of accelerated cooling, and outlet side temperature for controlled rolling. Is important, and a method of accurately measuring the temperature of the thick steel plate and a manufacturing facility with a devised arrangement of thermometers are adopted, and the material judgment is performed by these.

  For example, in Patent Document 1, the temperature distribution in the rolling direction and the width direction on only the final finish rolling delivery side is measured, a temperature difference with a required value is obtained, and this is used as an index to exclude a portion that deviates from this temperature difference index. The method of discarding is described.

However, the material of a thick steel plate changes depending on conditions such as controlled rolling and accelerated cooling, and the material changes due to a significant change in the structure. In particular, it is known that the temperature of the steel plate greatly affects the material. Yes. In the conventional method described in Patent Document 1, this finish rolling is performed because only the temperature at the final finish rolling exit side is evaluated even if the temperature history that the steel plate undergoing rolling undergoes in each facility changes. Judging from the temperature difference on the delivery side, there are many cases where products partially collected from large plates of heavy steel plates are out of the materials that should be guaranteed, and this is a serious problem because sufficient material quality cannot be guaranteed. It was. Further, as described in the example of Patent Document 1, since the temperature of either the upper surface or the lower surface is measured, it is not possible to evaluate the difference between the upper surface temperature and the lower surface temperature in the thick steel plate having a large plate thickness. In some cases, there was a strong demand for material guarantee in the thickness direction.
JP 52-117857 A

  In recent years, thick steel plates whose materials change sensitively even if the manufacturing conditions such as heat treatment materials fluctuate slightly are manufactured by the direct quenching method from the viewpoint of efficiency improvement, and TMCP technology is applied and expanded for rationalization. Conventionally, the material of the thick steel plate has been passed if it guarantees a part such as the central portion in the width direction. However, the demand for guaranteeing the entire surface of the steel plate has been issued by customers, and the severity has been increasing year by year. In line pipe original plates, ship building materials, etc., there is an unprecedented requirement to guarantee the strength deviation within a thick steel plate to a specific value or less.

  On the other hand, in the manufacturing process, a thick steel plate is passed through a continuous heating furnace, roughing mill, finish rolling mill, descaling device, accelerated cooling device, etc., so that the temperature distribution in the plate surface and thickness direction. Tends to be non-uniform, and as a result, the material tends to be non-uniform. Therefore, conventionally, for example, by using a radiation thermometer attached above the conveyance line, the temperature at the central part in the plate width direction of the thick steel plate is continuously measured in the rolling direction, and the measured temperature only at the central part falls within the allowable temperature range. If it is, the quality judgment of the entire thick steel plate is accepted, and if it is off, the quality judgment is rejected.

  However, this method cannot guarantee the material of the full width (that is, the entire surface) even on the surface where the temperature is measured, and the material guarantee is insufficient.

  In addition, since thick steel plates are manufactured in large quantities under the same manufacturing conditions, the conventional method for judging various materials using test pieces taken from the tip, center and tail positions in the rolling direction is to use test pieces of thick steel plates. In some cases, it may take several days after collection, and in the unlikely event that the judgment is impossible, all the thick steel plates manufactured during that period may be rejected and a large amount of defective materials may be generated.

  The present invention has been made in order to solve the above-described problems in guaranteeing the material, and accurately and promptly determines and guarantees the material of the steel plate that has been finish-rolled and accelerated and cooled. It aims at providing the material guarantee system of the thick steel plate which can do.

  In order to solve the above problems, the present invention measures and analyzes the temperature distribution of the entire surface of the thick steel plate on the thick steel plate production line, and determines the material of the thick steel plate based on the measurement and analysis results. I guarantee it.

  That is, in order to solve the above problems, the present invention has the following features.

[1] In a thick steel plate production line equipped with a finish rolling mill and an accelerated cooling device arranged on the downstream side of the finish rolling mill, the temperature of the entire upper surface or the entire lower surface of the thick steel plate is measured and analyzed to determine the thickness. A quality assurance system for thick steel sheets that guarantees the quality of steel sheets,
The material assurance system includes a temperature measurement unit and a temperature analysis unit,
The temperature measuring means includes a thermometer arranged in the vicinity of the finish rolling mill and in the vicinity of the accelerated cooling device, and a temperature collecting means for collecting the temperature measured by the thermometer,
The temperature analysis means creates the temperature MAP of the entire upper surface of the thick steel plate or the temperature MAP of the entire lower surface of the thick steel plate using the temperature measurement values collected by the temperature collecting means, and for the temperature MAP and the temperature MAP, A material assurance system for a thick steel plate, wherein a pass / fail judgment of the material of the thick steel plate is performed from an individual temperature threshold value selected from each set thermometer installation position.

[2] Measure and analyze the temperature of the entire upper surface of the thick steel plate and the temperature of the entire lower surface of the thick steel plate in a thick steel plate production line equipped with a finish rolling mill and an accelerated cooling device disposed downstream of the finish rolling mill. A steel plate quality assurance system that guarantees the material quality of the steel plate,
The material assurance system includes a temperature measurement unit and a temperature analysis unit,
The temperature measuring means includes a thermometer arranged in the vicinity of the finish rolling mill and in the vicinity of the accelerated cooling device, and a temperature collecting means for collecting the temperature measured by the thermometer,
The temperature analysis means creates a temperature MAP on the entire upper surface of the thick steel plate, a temperature MAP on the entire lower surface, and a temperature MAP at a predetermined position in the thickness direction using the temperature measurement values collected by the temperature collecting means. The thick steel plate is characterized in that pass / fail judgment of the material of the thick steel plate is performed from the temperature MAP and an individual temperature threshold value selected from each thermometer setting position set for the temperature MAP. Material guarantee system.

  ADVANTAGE OF THE INVENTION According to this invention, the material of the thick steel plate which was finish-rolled and accelerated-cooled can be determined and guaranteed accurately and rapidly. That is, in the present invention, since the material of the thick steel plate is determined based on the temperature distribution over the entire surface of the thick steel plate, it is possible to guarantee the material over the entire surface of the thick steel plate. In addition, immediately after finish rolling / accelerated cooling, it can be determined whether the temperature of the entire surface of the thick steel plate is within the allowable range, so the temperature of the subsequent thick steel plate can be controlled with reference to this temperature. It also has a secondary effect, can prevent the generation of a large amount of defective materials, can produce a thick steel plate efficiently and with good yield, and is extremely useful industrially.

  As described above, since the thick steel plate passes through a continuous heating furnace, rough rolling mill, finish rolling mill, descaling device, accelerated cooling device, etc., the temperature distribution in the plate surface and thickness direction tends to be non-uniform. . Since the material of the thick steel plate is greatly influenced by the temperature, the material tends to be non-uniform depending on the temperature in the passing step.

  Therefore, in order to guarantee the material of the thick steel plate, it is necessary to measure the temperature over the entire surface of the plate, and it is important to evaluate and judge the temperature over the entire upper surface or the entire lower surface.

  In addition, it is preferable to measure and analyze the entire plate temperature for each passing position (each equipment entry side or exit side) to make a judgment. However, in the examination by the present inventors, in particular, the material of the thick steel plate is affected. Since it has been understood that the large passing process is after the entrance to the finishing mill, in the present invention, the temperature in the vicinity of the finishing mill and in the vicinity of the accelerated cooling device is measured and analyzed over the entire upper surface and / or the entire lower surface of the thick steel plate. Decided to do.

  Since these temperature measurement and analysis results have a large amount of data, they can be easily determined by converting them to MAP (temperature distribution chart), and can be quickly converted to MAP by using a computer. Can be done.

  Based on this, the material guarantee system according to the present invention measures and analyzes the temperature of the entire upper surface of the thick steel plate and / or the temperature of the entire lower surface in the vicinity of the finish rolling mill and in the vicinity of the accelerated cooling device. A temperature measuring means and a temperature analyzing means are provided, and a steel plate full surface temperature MAP is created by the temperature analyzing means from the steel plate temperature measured by the temperature measuring means. On the basis of the individual temperature threshold values (hereinafter referred to as temperature threshold values) selected from the respective thermometer setting positions set for the thermometer, the pass / fail judgment of the material of the thick steel plate is performed.

  Details of the present invention will be described below.

  First, it is determined whether or not the rolled steel sheet to be manufactured is a material for which the entire surface is guaranteed. The target materials for which material guarantee is required over the entire surface are, for example, line pipe original plate, high-strength steel (for shipbuilding, DQ materials, tank materials, penstock, for industrial machinery, for building bridges, etc.) It is a steel plate whose material is easily affected by

  In the case of the entire surface material guarantee material, the surface temperature is measured / analyzed using means (temperature measuring means and temperature analyzing means) for measuring and analyzing the temperature over the entire upper surface and / or the entire lower surface of the thick steel plate. In the material assurance system according to the present invention, the temperature measurement means and the temperature analysis means are not particularly defined, but those having the configurations described below are suitable.

  For example, since it is difficult to actually measure all the temperatures over the entire upper surface and / or the entire lower surface of a thick steel plate production line, a spot type radiation thermometer and a scanning type capable of scanning in the width direction are located above the transport line. At least one spot-type radiation thermometer using an optical fiber (hereinafter referred to as an optical fiber radiation thermometer) is preferably installed in the width direction below the radiation thermometer. Further, it is preferable to collect the temperatures measured by the plurality of thermometers using a process computer, and further analyze the temperature over the entire upper surface or / and the entire lower surface of the thick steel plate based on the measurement results to make a MAP. .

  In the temperature measurement means, the above thermometers are combined as appropriate, and the minimum required temperature measurement position for guaranteeing the temperature history of the upper surface or the lower surface on the production line is the front and rear surfaces of the finish rolling mill and the front and rear surfaces of the acceleration cooling device. Place a thermometer on the surface. When the temperature difference between the upper and lower surfaces of the thick steel plate is expected to be large, such as when the plate thickness is increased, the material characteristics of the upper and lower surfaces are different, so the temperature needs to be measured on the entire upper surface and the entire lower surface.

  For example, installing a thermometer on the front face of the finish rolling mill means that a thermometer is arranged in a position closer to the finish rolling mill than other devices in the immediate vicinity of the finish rolling mill. In addition, installing a thermometer on the rear surface of the finish rolling mill means that a thermometer is disposed in a position closer to the finish rolling mill than other devices in the immediate vicinity of the rear of the finishing mill. The same applies to the acceleration cooling device.

  Further, for example, the spot type radiation thermometer may be disposed above the transport line on the front and rear surfaces of the finish rolling mill and the front and rear surfaces of the cooling device.

  A plurality of spot type radiation thermometers may be arranged on the front and rear surfaces of the finish rolling mill. This is because if there is only one thermometer, the rolling must be stopped if the thermometer becomes abnormal. If there are multiple thermometers, one normal thermometer can be used as it is and mass production is possible. This is because trouble can be avoided so that a large amount of defective material is not produced in the manufacture of thick steel plates to be produced. The arrangement position of the plurality of units is not particularly defined, but it is desirable to arrange them in the conveying direction of the thick steel plates.

  The spot-type radiation thermometer arranged on the front and rear surfaces of the acceleration cooling device may be a single front surface and the rear surface may be a plurality of units with two specifications for high temperature measurement and low temperature measurement.

  This is because the temperature of the steel sheet on the outlet side of the accelerated cooling device varies in a wide range from about 600 ° C. to a room temperature level and from a low temperature to a high temperature.

  However, the existing thermometer cannot measure a wide range of temperature from low temperature to high temperature (room temperature to about 700 ° C.) with high resolution (preferably ± 5 ° C. or less). Therefore, at least two types of thermometers for high temperature measurement and low temperature measurement are preferably installed. Moreover, it is good to arrange | position for the high temperature measurement in the side close | similar to an acceleration cooling device, and the object for low temperature measurement in the distant side.

  The scanning radiation thermometer that measures the temperature distribution in the width direction is preferably arranged on the upper surface side of the transport line, on the rear surface of the finish rolling mill, and on the front and rear surfaces of the acceleration cooling device. In addition, preferably, when placed close to the spot type radiation thermometer, the values of the thermometers can be compared and referred to, and accurate measurement is possible.

  The reason why the width direction thermometers are installed on the rear surface of the finish rolling mill and the front and rear surfaces of the accelerated cooling device is that these regions are temperature regions where the material changes greatly, and temperature distribution tends to occur in the width direction. For this reason, in order to make the material uniform over the entire surface of the thick steel plate, it is necessary to measure in the width direction.

  As an alternative to the scanning radiation thermometer that can measure in the width direction, an infrared thermography device that captures luminance and measures temperature as a surface may be used.

  The optical fiber radiation thermometer may be arranged below the production line. Below the production line, the temperature measurement environment is particularly bad due to water, water vapor, etc., and it is extremely difficult to install a scanning radiation thermometer that measures the temperature of the entire lower surface. Especially in the immediate vicinity of the finish rolling mill, a large amount of cooling water is supplied, and the environment for temperature measurement is significantly deteriorated. In addition, a large number of conveying rollers are installed in the production line, and the space for inserting the thermometer is narrow, which is why the optical fiber radiation thermometer is applied.

  When the optical fiber radiation thermometer is placed at the front and back faces of the finish rolling mill and the front and rear faces of the cooling device, and below the transport line, at the position facing the spot-type radiation thermometer placed on the upper surface across the transport line Good. This is because the difference between the temperature of the upper surface and the temperature of the lower surface can be grasped at the same position in the width direction, so that the material in the plate thickness direction can be estimated, which is useful for quality assurance.

  In addition, along the scanning direction of the scanning radiation thermometer, at a position facing the scanning radiation thermometer disposed on the rear surface of the finishing mill and the front and rear surfaces of the cooling device with the transportation line interposed therebetween. A plurality of optical fiber radiation thermometers may be arranged. As a result, the temperature distribution in the plate thickness direction can be grasped two-dimensionally, and temperature measurement and analysis from the entire upper surface to the entire lower surface of the thick steel plate can be performed.

  In order to measure the temperature in the width direction of the lower surface, the more the number of fiber optic radiation thermometers, the more details can be grasped quantitatively, but from the viewpoint of cost and maintenance, an interval of about 1 location / m in the width direction. It is good to do.

  The measured temperature data measured by these thermometers is taken into the process computer, and the temperature distribution of the entire upper surface and the entire lower surface is calculated using the measured temperature data and the analyzed temperature data analyzed and calculated based on the measured temperature data. Turn into. Thereby, the temperature of the whole thick steel plate in the entrance side and exit side of each apparatus (finish rolling mill and accelerated cooling apparatus) can be grasped at a glance.

  When determining the material using the MAP temperature distribution, for example, based on the actual value of the material test, the upper and lower limit values of the allowable temperature range on each of the device entrance side and the exit side, that is, the temperature By providing the threshold value, the portion of the thick steel plate that falls within the allowable temperature range can be determined as a non-defective product, and can be cut and shipped.

  For example, for the finish rolling mill entry side, finish rolling mill exit side, accelerated cooling device entrance side, and accelerated cooling device exit side, the temperature distribution is converted to MAP, and the temperature for each MAP is determined according to the material requirements for each product of the thick steel plate. It is preferable to set a threshold value, make a pass / fail judgment using the MAP and temperature threshold value, and collect the corresponding product.

  In more detail, in the case of demanding materials, the product may be taken from the part of the thick steel plate where the temperature on the entry side and the exit side in the finish rolling mill and the accelerated cooling device falls within the temperature threshold. The material is guaranteed. In addition, if the product requirements are not strict, for example, the product material is taken from the part of the thick steel plate where the temperatures on the exit side of the finish rolling mill and the exit side of the accelerated cooling device fall within the respective temperature thresholds. According to requirements, based on the temperature thresholds on the exit side of the finishing mill and on the entry side and / or exit side of the accelerated cooling device, the corresponding product can be taken from the portion of the thick steel plate that falls within that temperature threshold. .

  Furthermore, for extremely thick steel plates with a large thickness or severely thick steel plates, the temperature distribution in the plate thickness direction is unknown in the temperature measurement / analysis on the entire upper surface or only the entire lower surface, and this may not allow material judgment. is there. In this case, the temperature MAP is created by analyzing the temperature at a predetermined position in the plate thickness direction of the thick steel plate, and the temperature change (temperature distribution) in all the plate longitudinal direction, plate width direction, and plate thickness direction of the thick steel plate. The temperature threshold value may be set while grasping at the entry side and the exit side of the finish rolling mill and the accelerated cooling device.

  One embodiment of the present invention as described above will be described below with reference to the drawings.

  FIG. 3 shows an outline of an example of a material assurance system provided with a temperature measuring means (thermometer and temperature collecting means) and a temperature analyzing means in this embodiment, and FIG. 4 shows the configuration of the temperature measuring means. Some examples are shown. In these figures, 1 is a heating furnace, 2 is a finish rolling mill, 3 is a thick steel plate, 4 is a cooling device between rolling passes (cooling device for controlled rolling), 5 is an accelerated cooling device, 6, 6a, 6b, 6c. , 6d is a scanning radiation thermometer, 6c is for high temperature measurement, 6d is for low temperature measurement, 7, 7a, 7b, 7c, 7d are optical fiber radiation thermometers, 7c is for high temperature measurement, 7d is for low temperature measurement, 8 Is a controlled rolling start temperature / finishing temperature collection process computer, 9 is a cooling start temperature collection process computer, 10 is a cooling stop temperature collection process computer, 11 is a temperature performance analysis process computer, 12 is a bottom surface temperature collection process computer, and 13 is a top surface temperature. Figure 2 shows a collection process computer. However, in the figure, the roughing mill and the spot type radiation thermometer are omitted.

  Measured with a steel plate temperature measuring means composed of a spot type radiation thermometer (not shown) arranged on the front and back surfaces of the finish rolling mill 2, and a scanning type radiation thermometer 6a and an optical fiber radiation thermometer 7a arranged on the rear surface. The obtained temperature is taken into the control rolling start temperature / finishing temperature collection process computer 8.

  The temperatures measured by the spot-type radiation thermometer (not shown), the scanning radiation thermometer 6b, and the optical fiber radiation thermometer 7b arranged in front of the accelerated cooling device 5 are taken into the cooling start temperature collection process computer 9. .

  The temperature measured by a temperature measuring means comprising a spot type radiation thermometer (not shown in the figure), scanning type radiation thermometers 6c, 6d and optical fiber radiation thermometers 7c, 7d arranged on the rear surface of the acceleration cooling device 5 is The cooling stop temperature collection process computer 10 takes in.

  The temperature collecting means is composed of a finishing temperature collecting process computer 8, a cooling start temperature collecting process computer 9 and a cooling stop temperature collecting process computer 10, each comprising an upper surface temperature collecting process computer 13 and a lower surface temperature collecting process computer 12. Each of the collected thick steel plate upper surface temperature and lower surface temperature is taken into the temperature performance analysis process computer 11 which is a temperature analysis means.

  The actual temperature analysis process computer 11 performs analysis / calculation based on the measured temperature data captured by the finishing temperature collection process computer 8, the cooling start temperature collection process computer 9 and the cooling stop temperature collection process computer 10, and the measured temperature data. Based on the analysis temperature data, the temperature distribution of the entire upper surface and / or the entire lower surface is converted to MAP, and the temperature threshold for each MAP and device (finishing mill entry temperature, finish rolling exit temperature, acceleration cooling device entry side) If the temperature is within the temperature threshold value of each device corresponding to each product, the product is measured from the large plate of the thick steel plate.

  FIG. 1 shows a processing flow of the material assurance system for a thick steel plate according to this embodiment. Here, the temperature measurement / analysis result (temperature MAP) taken in and analyzed by the temperature performance analysis process computer 11 is compared with the temperature threshold value set for the temperature measurement / analysis result to determine whether or not the product shipment is appropriate. ing. FIG. 2 is a process computer screen for visually displaying the process.

  First, the above-described temperature measuring means and temperature analyzing means measure and analyze the entire upper surface temperature or lower surface temperature of the thick steel plate (S1), and the temperature analyzing means measures the upper surface entire surface temperature MAP or the entire lower surface temperature of the thick steel plate (large plate 14). A temperature MAP is created (S2). Here, the size of the mesh of the temperature MAP is appropriately selected depending on the application, but preferably in the range of 50 to 1000 mm. Incidentally, the mesh of the temperature MAP refers to one small region when the entire surface of the steel plate is divided into small regions in order to create the entire surface temperature MAP of the steel plate.

  When a temperature distribution in the plate thickness direction is required, such as a very thick steel plate having a large plate thickness, in (S2) above, the upper surface whole surface temperature MAP, the lower surface whole surface temperature MAP, and the temperature at a specific position in the plate thickness direction. Create a MAP. At that time, in (S1), the upper surface temperature and the lower surface temperature of the thick steel plate are measured and analyzed.

  Next, as shown in FIG. 2, with respect to the large plate 14, a material test tip sampling material 15, a material test center sampling material 16, a material test tail sampling material 17, a product (small plate 18, 19, 20, 21) is assigned (S3).

  Note that by calculating the temperature at the sampling position for material test from the temperature MAP and correlating the material test result with the temperature MAP, it is possible to improve the quality design and material prediction accuracy of the thick steel plate.

  Next, a temperature upper and lower limit value (temperature threshold value) indicating a specific allowable temperature range is set for each device input side or output side so as to correspond to the created temperature MAP, and the temperature is the temperature threshold value. The area outside the area is surrounded by thick frames 22 and 23 (S4).

  Note that the thick frame portion outside the allowable temperature range may be reassigned by changing the sampling position according to the product if it can be diverted to another less demanding product (S5).

  Then, a product whose temperature is within the temperature threshold is collected as a product (S6).

  In this way, the steel plate material assurance system according to this embodiment uses the temperature distribution of the entire surface of the thick steel plate, which has been accurately measured and analyzed, as a MAP, and based on the actual temperature value (actual temperature measurement value). Therefore, it is possible to ship a product whose entire surface is guaranteed. Also, the shape (flatness etc.) can be guaranteed over the entire surface.

  In the conventional material judgment / guarantee method, material defects are mixed to some extent (for example, about 0.8%) in the product collected from the large plate, and the product must be recreated from the large plate, and the product is collected again. However, according to this embodiment, the material defect portion in the material determination is almost zero. The material that has been significantly reduced and the collected products can be guaranteed with certainty, and the yield is efficient and the yield is good, and secondary effects such as the suppression of shape defects in thick steel plates are obtained. The effect is remarkably large.

The figure which shows the processing flow of one Embodiment of this invention. The figure which shows the process computer screen in one Embodiment of this invention. The figure which shows the outline | summary of the material guarantee system which concerns on one Embodiment of this invention. The figure explaining a part of material guarantee system shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Finishing rolling mill 3 Steel plate 4 Rolling pass cooling device 5 Acceleration cooling device 6, 6a, 6b, 6c, 6d Width direction scanning type radiation thermometer 7, 7a, 7b, 7c, 7d Optical fiber radiation thermometer 8 Control Rolling start temperature / finishing temperature collection process computer 9 Cooling start temperature collection process computer 10 Cooling stop temperature collection process computer 11 Temperature performance analysis process computer 12 Lower surface temperature collection process computer 13 Upper surface temperature collection process computer 14 Large plate 15, 16, 17 Material Sampling material for test 18, 19, 20, 21 Small plate 22, 23 Plate portion outside temperature threshold (indicated by thick frame)

Claims (1)

In a thick steel plate production line equipped with a finish rolling mill and an accelerated cooling device arranged downstream of the finish rolling mill, the temperature of the entire upper surface of the thick steel plate and the temperature of the entire lower surface of the thick steel plate are measured and analyzed to determine the thickness. A quality assurance system for thick steel sheets that guarantees the quality of steel sheets,
The material assurance system includes a temperature measurement unit and a temperature analysis unit,
The temperature measuring means includes a thermometer arranged in the vicinity of the finish rolling mill and in the vicinity of the accelerated cooling device, and a temperature collecting means for collecting the temperature measured by the thermometer,
The temperature analysis means creates a temperature MAP on the entire upper surface of the thick steel plate, a temperature MAP on the entire lower surface, and a temperature MAP at a predetermined position in the thickness direction using the temperature measurement values collected by the temperature collecting means. The thick steel plate is characterized in that pass / fail judgment of the material of the thick steel plate is performed from the temperature MAP and an individual temperature threshold value selected from each thermometer setting position set for the temperature MAP. Material guarantee system.

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