JP2010214442A - Quality guarantee facility for thick steel sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quality guarantee facility for a thick steel sheet which enables operation management to improve quality uniformity in the sheet thickness direction of the thick steel sheet and in a steel sheet surface. <P>SOLUTION: A thick steel sheet manufacturing line includes a finishing mill and an accelerated cooling device installed at the downstream side of the finishing mill. The quality guarantee facility for the thick steel sheet includes a temperature measuring means for measuring a steel sheet temperature and an actual temperature analyzing means for analyzing the measured steel sheet temperatures. The temperature measuring means comprises spot type radiation thermometers and scanning type radiation thermometers installed at the respective positions of the rear surface of the finishing mill and the rear surface of the accelerated cooling device above the upper surface side of the thick steel sheet manufacturing line, optical fiber radiation thermometers installed at positions corresponding to the spot type radiation thermometers on the upper surface side at the lower surface side of the thick sheet manufacturing line, and a plurality of optical fiber radiation thermometers installed at positions corresponding to the scanning type radiation thermometers in a line width direction at optional intervals. The actual temperature analyzing means comprises a means for obtaining temperature distribution of entire steel sheet from the steel sheet temperatures measured with the respective temperature measuring means. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a steel sheet quality assurance facility in a thick steel plate production line, and more particularly to a material suitable for guaranteeing the quality of the entire surface of a thick steel sheet to be subjected to controlled rolling or accelerated cooling.

  In order to produce TMCP that improves the strength and toughness of the steel sheet with a microstructure having a crystal grain size of about 1 μm, and a steel sheet with less deformation such as warpage by controlling internal stress, the control rolling start temperature, Since it is necessary to strictly control the end temperature, the cooling stop temperature of the accelerated cooling, and the like, various measuring methods for measuring the steel plate temperature with high accuracy and various cooling facilities in which the thermometer is arranged have been proposed.

  Patent Document 1 relates to a cooling control device for hot-rolled steel plates. In order to prevent shape defects due to warpage in the plate width direction during cooling, the steel plate temperature is measured, and each nozzle disposed above and below the cooling device. The amount of cooling water and the start and end of cooling are strictly controlled, and optical fiber radiation thermometers are arranged on the rear surface of the finishing mill, on the front and rear surfaces of the cooling device, and inside.

  Patent Document 2 relates to a method for controlling the shape of a controlled cooling steel plate, estimating the shape after cooling at normal temperature of the accelerated cooling steel plate from the shape immediately after cooling and the temperature history of the steel plate, ensuring the shape of the next material, and the inside of the accelerated cooling device Describes that a steel plate surface temperature distribution meter (thermotracer) and a steel plate surface thermometer are arranged immediately after the steel plate front and back surface temperature measuring thermometer and the accelerated cooling device.

  Patent Document 3 relates to a method for cooling a thick steel plate, and in order to improve the flatness of the steel plate shape and to make the material uniform, after finish rolling, the thickness of the scale thickness is controlled to 10 μm or less by descaling or surface film coating. And disposing a radiation thermometer as a steel plate surface thermometer in front of the control cooling device.

Japanese Patent Publication No. 7-41303 Japanese Patent Laid-Open No. 10-5868 Japanese Patent Laid-Open No. 2001-300627

  In recent years, high-Ni steel, which has high material sensitivity to fluctuations in manufacturing conditions, has been manufactured by direct quenching, and TMCP has been applied to increase the rationalization of the product, so that users are required to guarantee the quality of the product's entire surface. Has increased.

  Thick steel plates tend to have non-uniform temperature distribution in the plate thickness direction and in the steel plate surface due to a continuous heating furnace, descaling device, cooling equipment, etc., and as a result, the material tends to be non-uniform.

  As a countermeasure, for example, measure the temperature of the steel sheet with a radiation thermometer attached above the transfer line, and if the measured temperature is within the control temperature range, the quality judgment is passed. Refusing was done.

  However, quality judgment using the temperature measurement result by the radiation thermometer measures the temperature at the center in the width direction of the steel sheet with the radiation thermometer attached to the upper surface at the center in the conveyance line width direction. Since the temperature range is contrasted and the quality judgment is performed only at the temperature in the center part in the width direction of the steel sheet, the material guarantee other than in the center part in the width direction of the steel sheet is insufficient.

  In addition, the method of performing various material tests on test pieces taken from the top, middle, and end positions of the large plate in the rolling direction requires several days after rolling and shearing the steel plate. When manufacturing in large quantities under the same manufacturing conditions, when the results of material testing are known after a few days, it is already after mass production has been completed, optimization of the conditions is not in time, and mass nonconformities may occur. obtain.

  Therefore, the present invention is capable of operation management to improve the material uniformity in the plate thickness direction and the steel plate surface of the thick steel plate by appropriately arranging a thermometer for measuring the steel plate temperature in the thick steel plate production line, The purpose is to provide equipment for guaranteeing the quality of thick steel plates.

  Note that the upper side of the plate passing direction (FIG. 1) of the thick steel plate is referred to as the front side, and the lower side is referred to as the rear side.

  In order to solve the above problems, the present invention has the following features.

  The first invention relates to a temperature measuring means for measuring a steel plate temperature and a temperature for analyzing the measured steel plate temperature in a thick steel plate production line equipped with a finishing mill and an accelerated cooling device installed downstream of the finishing mill. A steel plate quality assurance facility with performance analysis means, wherein the temperature measuring means is installed at each position on the rear surface of the finishing mill and the rear surface of the accelerated cooling device above the upper surface side of the thick steel plate production line. Spot-type radiation thermometer and scanning radiation thermometer, optical fiber radiation thermometer installed at a position corresponding to the spot-type radiation thermometer on the upper surface side on the lower surface side of the thick plate production line, and the scanning A plurality of optical fiber radiation thermometers installed at arbitrary intervals in the line width direction at a position corresponding to the type radiation thermometer, and the temperature performance analysis means is a steel measured by each temperature measurement means The material guarantee facility steel plate is characterized in that it comprises means for determining the temperature distribution of the entire steel sheet temperature.

  According to a second aspect of the present invention, the temperature measuring means installed on the upper surface side of the thick steel plate production line includes a scanning radiation thermometer and a plurality of spot radiation thermometers on the rear surface of the finish rolling mill, and an accelerated cooling device. The scanning radiation thermometer and the spot radiation thermometer are each composed of a plurality of high temperature range measurement thermometers and low temperature range measurement thermometers on the rear surface. This is a material guarantee facility for thick steel plates.

  A third aspect of the invention is a spot-type radiation thermometer and a scanning radiation thermometer installed on the rear surface of the accelerated cooling device, respectively, a high temperature range measurement thermometer for measuring a temperature range of 200 ° C. or more and 700 ° C. or less, The equipment for assuring the quality of a thick steel plate according to the second invention, comprising a thermometer for low temperature region measurement that measures a temperature range of 50 ° C. or higher and 300 ° C. or lower.

  According to the present invention, it is possible to guarantee the material and shape of the thick steel plate that is subjected to accelerated cooling or directly quenched after finish rolling. In addition, since it is possible to determine whether or not the temperature of the entire surface of the steel sheet is right after rolling, it is possible to prevent the occurrence of mass nonconformity by controlling the temperature of the subsequent steel sheet, which is extremely useful industrially.

It is a figure which shows one Embodiment of the outline | summary of the quality assurance equipment of the thick steel plate which concerns on this invention. It is a figure explaining the transmission flow of the temperature information which concerns on this invention. It is a figure explaining the transmission flow of the upper and lower surface temperature information which concerns on this invention.

  The thick steel plate material guarantee facility according to the present invention includes a temperature measuring means and a temperature performance analyzing means. In the production line for thick steel plates, it is technically difficult to measure the temperature of the entire surface of the thick steel plates. Therefore, in the present invention, the temperature measuring means is a thermometer as a spot type radiation thermometer above the upper surface of the conveying line. A scanning type radiation thermometer, a spot type radiation thermometer using an optical fiber on the lower surface (hereinafter referred to as an optical fiber radiation thermometer), and a process computer (hereinafter referred to as a PC) for collecting the temperature measured by a plurality of thermometers. Called).

  In the present invention, by combining the above thermometers as appropriate, the minimum temperature measurement position required to guarantee the temperature history of the entire surface of the steel sheet on the production line is 1. 1. Rear face of finish mill and A thermometer is installed as the rear surface of the accelerated cooling device. When the temperature difference between the upper and lower surfaces of the steel plate is significant, the material properties of the upper and lower surfaces of the steel plate may be different, and therefore the temperature is measured on the upper and lower surfaces of the steel plate.

  In the present invention, the installation of a thermometer on the rear surface of the finish rolling mill means that a thermometer is installed at a location closer to the finishing mill than other equipment, in the immediate vicinity of the rear of the finishing mill. The same applies to the acceleration cooling device.

  The spot type radiation thermometer is disposed above the upper surface side of the transfer line, on the rear surface of the finishing mill and on the rear surface of the acceleration cooling device.

  Although the spot type radiation thermometer (7a) installed on the rear surface of the finishing mill may be single, it is more preferable to install a plurality of spot type radiation thermometers so that mutual detection of the thermometer abnormality can be detected. Compared to the case of one thermometer, it is possible to prevent the mill from stopping when an abnormal thermometer occurs, and to improve the reliability of the measured temperature when manufacturing large-scale line pipe materials. It is. The installation positions of the plurality of thermometers are not particularly defined, but they are preferably arranged in the transport direction.

  In finish rolling, even if the thermometer is on either the front or the rear of the rolling mill, the measured temperature can be used as the control rolling start temperature and the rolling finishing temperature.

  That is, the controlled rolling is not necessarily started from the first pass of finish rolling, and is often performed after performing a plurality of passes. In that case, it is possible to determine whether or not the temperature suitable for control rolling has been reached by using a thermometer on either the front or rear surface of the finish rolling mill. In addition, the rolling finishing temperature at the end of rolling can also be measured.

  Furthermore, the finishing mill may be passed by an empty pass, and the path at the start of the controlled rolling is not limited to the sheet passing direction of the production line, and the thermometer is on either the front or the rear of the rolling mill. Even in this case, if the initial rolling pass of controlled rolling is started from the thermometer installation direction, the controlled rolling start temperature can be measured, and if the final pass is terminated in the thermometer installation direction, the rolling finishing temperature can be measured. It is.

  The spot type radiation thermometers (7c, 7d) and the scanning type radiation thermometers (6c, 6d) installed on the rear surface of the acceleration cooling device are two kinds of temperatures, a high temperature range measurement thermometer and a low temperature range measurement thermometer. Use a meter.

  In the accelerated cooling system, the cooling stop temperature fluctuates in a wide range from low to high, such as accelerated cooling with a cooling stop temperature of around 600 ° C and direct quenching where the cooling stop temperature is close to room temperature. Become.

  However, since it is difficult to keep the resolution of the thermometer within ± 5 ° C in a wide range of temperature measurement from low temperature to high temperature (about 50-700 ° C), the high temperature range measurement thermometer (7c, 6c) It is necessary to install two types of thermometers (7d, 6d). The high temperature range measurement thermometers (7c, 6c) and the low temperature range measurement thermometers (7d, 6d) may be installed in this order from the machine side of the acceleration cooling apparatus toward the downstream direction of the transfer line. In addition, the thermometer for high temperature range measurement (7c, 6c) which measures the temperature range of 200 degreeC or more and 700 degrees C or less, and the low temperature range measurement thermometer which measures the temperature range of 50 degreeC or more and 300 degrees C or less (7d, By using 6d), a resolution of ± 5 ° C. can be ensured, and accurate temperature measurement is possible.

  In addition, the controlled rolling start temperature / rolling finishing temperature measured on the rear surface of the finishing mill and the steel plate temperature measured on the rear surface of the accelerated cooling device have a large effect on the material. It is necessary to guarantee the material uniformity by the temperature uniformity of the entire steel sheet.

Therefore, the scanning radiation thermometer is installed so as to scan the width direction of the steel sheet on the rear surface (6a) of the finishing mill and the rear surfaces (6c, 6d) of the accelerated cooling device above the upper surface side of the conveying line. To do. This is because the entire surface temperature can be measured by moving the steel sheet in the longitudinal direction by installing the width direction scanning type. In addition, it is preferable to install in the vicinity of the spot type radiation thermometer. Thereby, mutual check of the thermometer abnormality detection is possible, and the reliability of the measured temperature can be improved.
As the scanning thermometer, an existing thermometer such as a rotating mirror type or a linear ray type may be appropriately selected according to the temperature measurement location.

  The optical fiber radiation thermometer is installed on the lower side of the transport line. The lower surface side of the transfer line is in an environment filled with various cooling water, steam, etc., and if a CR shower is installed on the downstream side closest to the finishing mill, the temperature measurement environment on the rear surface of the finishing mill is more It will get worse. Therefore, it is difficult to accurately measure the temperature for a long time even if an ordinary spot type radiation thermometer or scanning radiation thermometer is installed in the vicinity of the rolling mill and in the vicinity of the lower surface side of the hot steel sheet. On the other hand, the optical fiber radiation thermometer is hardly affected by various cooling water and water vapor, and can be placed in a narrow space. Therefore, an optical fiber radiation thermometer is used on the lower surface side of the transport line.

  The fiber optic radiation thermometer is installed on the lower surface side of the corresponding conveyance line across the transportation line and the installation position of the spot type radiation thermometer located on the rear surface of the finishing mill and the front and rear surfaces of the accelerated cooling device on the upper surface side of the transportation line To do.

  Also, the scanning radiation thermometer scanning direction is located at the rear surface of the finishing mill and the position of the scanning radiation thermometer located on the front and back surfaces of the acceleration cooling device and the lower surface side of the corresponding transportation line across the transportation line. A number of optical fiber thermometers will be installed along the line.

  As the number of installed fiber optic thermometers increases, the temperature distribution in the width direction can be accurately and quantitatively grasped. However, from the viewpoint of cost and maintenance, an interval of 1 location / m is a minimum requirement. When the optical fiber radiation thermometer is arranged at a position on the lower surface side of the transport line corresponding to the installation position of the spot type radiation thermometer on the upper surface side of the transport line, a plurality of units may be installed in the width direction of the transport line.

FIG. 1 shows an embodiment of the outline of the material guarantee facility for thick steel plates according to the present invention provided with the above-described steel plate temperature measuring means, and FIG.
The thick steel plate production line includes a heating furnace 1, a finish rolling mill 2, a CR shower 4 and an accelerated cooling device 5, and FIG. 1 shows a state in which the steel plate 3 is positioned between the finishing mill 2 and the CR shower 4. Indicates.

  7a, 7c and 7d are spot type radiation thermometers, 6a, 6c and 6d are scanning type radiation thermometers, 7a measures the temperature distribution in the length direction of the upper surface of the steel sheet immediately after finish rolling, and 6a is immediately after finish rolling. The temperature distribution in the width direction and length direction of the upper surface of the steel plate is measured, and the data is sent to the control rolling start temperature / finishing temperature collection PC 11 as shown in FIG. 7c, 7d, 6c, and 6d are installed on the exit side of the acceleration cooling device, 7c and 6c are high temperature range measurement thermometers, 7d and 6d are low temperature range measurement thermometers, and 6c and 6d are acceleration coolings. The temperature distribution in the width direction and the length direction of the upper surface of the steel sheet immediately after, and the temperature distribution in the length direction are measured by 7c and 7d, and the data is sent to the cooling stop temperature collection PC13. 7c and 6c may be used for temperature control of the accelerated coolant, and 7d and 6d may be used for temperature control of the direct quenching material.

  8a, 8c and 8d are optical fiber radiation thermometers, 8a measures the temperature distribution in the width direction and length direction of the lower surface of the steel sheet immediately after finish rolling, and the data is sent to the control rolling start temperature / finishing temperature collection PC11. 8c and 8d are installed on the exit side of the acceleration cooling device, 8c is a thermometer for high temperature region measurement, and 8d is a thermometer for low temperature region measurement, both of which are in the width direction and length of the lower surface of the steel plate immediately after accelerated cooling. The temperature distribution in the direction is measured, and the data is sent to the cooling stop temperature collection PC 13. 8c may be used for the temperature control of the accelerated coolant and 8d for the direct quenching material.

  Next, a transmission flow in which steel plate temperature information measured by each thermometer is sent to each PC will be described with reference to FIGS. 11 is a control rolling start temperature / finishing temperature collection PC, 13 is a cooling stop temperature collection PC, and 14 is a temperature performance analysis PC.

  The steel plate upper surface temperature information measured by the spot type radiation thermometer 7a and the scanning radiation thermometer 6a installed on the rear surface of the finishing mill and the steel plate lower surface temperature information measured by the optical fiber radiation thermometer 8a are the upper surface temperature collecting PC 15a. Then, it is sent to the controlled rolling start temperature / finishing temperature collecting PC 11 through the lower surface temperature collecting PC 16a, and the rolling temperature management such as the controlled rolling starting temperature and the rolling finishing temperature, and the temperature distribution in the steel plate width and length directions are managed.

  Steel plate upper surface temperature information measured by spot-type radiation thermometers 7c, 7d and scanning radiation thermometers 6c, 6d installed on the rear surface of acceleration cooling device 5, and steel plates measured by optical fiber radiation thermometers 8c, 8d The lower surface temperature information is sent to the cooling stop temperature collection PC 13 via the upper surface temperature collection PC 15c and the lower surface temperature collection PC 16c, and the accelerated cooling stop temperature management, the steel plate width, and the temperature distribution in the length direction are managed.

  As shown in FIG. 3, the control rolling start temperature / finishing temperature collection PC11 and the cooling stop temperature collection PC13 are composed of an upper surface temperature collection PC15a and a lower surface temperature collection PC16a. The collection PC 13 includes an upper surface temperature collection PC 15c and a lower surface temperature collection PC 16c, and the steel plate temperatures collected in the upper and lower surface temperature collection PCs are controlled rolling start temperature / finishing temperature collection PC 11 and cooling stop temperature collection PC 13, respectively. After that, it is taken into the temperature performance analysis PC 14.

  In actual machine production, the operation control temperature (controlled rolling start temperature / rolling finishing temperature, cooling stop temperature) range and the temperature measurement results taken in the temperature performance analysis PC 14 are compared, and the quality judgment is performed to compare the entire surface of the steel sheet. The material can be guaranteed.

  In addition, in the temperature performance analysis PC14, the entire temperature of the finish rolling mill delivery side and the accelerated cooling device delivery side is grasped, and the material is determined from a specific threshold value, temperature allowable range, material model, etc., and desired from the large plate. The information of the cut-out part that can secure the material to be output is output.

  Moreover, the upper and lower surface temperature of the slab in the heating furnace after the next material is adjusted from the temperature difference between the upper and lower surfaces, and the water amount of the accelerated cooling equipment is controlled in the width direction and the longitudinal direction from the temperature distribution in the steel plate width direction and the longitudinal direction. Thereby, the defect of a steel plate shape can be reduced.

  According to the present invention, the material test failure rate has been reduced by about 30% compared to the prior art, the warpage correction time of the steel sheet has been reduced by about 20%, and the defective shape of the steel sheet has been reduced by about 10%. .

DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Finishing mill 3 Steel plate 4 CR shower 5 Accelerated cooling device 6a, 6c, 6d Scan type radiation thermometer 7a, 7c, 7d Spot type radiation thermometer 8a, 8c, 8d Optical fiber radiation thermometer 11 Control rolling start temperature -Finishing temperature collection PC
13 Cooling stop temperature collection PC
14 Temperature performance analysis PC
15a, 15c Upper surface temperature collection PC
16a, 16c Bottom surface temperature collection PC

Claims (3)

  In a thick steel plate production line equipped with a finishing mill and an accelerated cooling device installed on the downstream side of the finishing mill, a temperature measuring means for measuring the steel plate temperature and a temperature performance analyzing means for analyzing the measured steel plate temperature are provided. This is a spot-type radiant temperature installed at the respective positions on the rear surface of the finish rolling mill and the rear surface of the accelerated cooling device above the upper surface side of the thick steel plate production line. Corresponding to the scanning radiation thermometer, optical fiber radiation thermometer installed on the lower surface side of the thick plate production line at the position corresponding to the spot radiation thermometer on the upper surface side, and the scanning radiation thermometer A plurality of optical fiber radiation thermometers installed at arbitrary intervals in the line width direction at the position where the temperature results are analyzed by the steel sheet temperature from the steel sheet temperature measured by each temperature measuring means. Material guarantee facility steel plate which comprises a means for determining the temperature distribution in the body.   The temperature measuring means installed on the upper surface side of the thick steel plate production line includes a scanning radiation thermometer and a plurality of spot type radiation thermometers on the rear surface of the finishing mill, and a scanning radiation device on the rear surface of the accelerated cooling device. The material assurance equipment for thick steel plates according to claim 1, wherein each of the thermometer and the spot type radiation thermometer comprises a plurality of high temperature range measurement thermometers and low temperature range measurement thermometers. .   A spot-type radiation thermometer and a scanning radiation thermometer installed on the rear surface of the accelerated cooling device are a high-temperature range measurement thermometer for measuring a temperature range of 200 ° C. or more and 700 ° C. or less, and a temperature of 50 ° C. or more and 300 ° C. or less, respectively. The material guarantee equipment for thick steel plates according to claim 2, comprising a thermometer for low temperature range measurement for measuring the temperature range of the steel sheet.

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