JP5310151B2 - Thick steel plate quality assurance equipment - Google Patents

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 manage the end temperature and the cooling stop temperature of the accelerated cooling, various measuring methods for measuring the steel plate temperature with high accuracy and various cooling equipments that devise the arrangement of thermometers 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 also performed only at the temperature in the central part in the width direction of the steel sheet, the material assurance other than in the central part in the width direction of the steel sheet was 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.

  1st invention analyzes the measured steel plate temperature with the temperature measurement means which measures a steel plate temperature in the thick steel plate manufacturing line provided with the finishing rolling mill and the accelerated cooling device installed in the downstream of the finishing mill It is a material guarantee facility for a thick steel plate provided with a temperature performance analysis means, and the temperature measurement means is a spot type radiation thermometer installed on the front surface of the finishing mill above the upper surface side of the thick steel plate production line, A spot type radiation thermometer and a scanning type radiation thermometer installed on the rear surface of the accelerated cooling device, and a spot type radiation thermometer on the lower surface side of the thick plate production line on the front surface of the finishing mill and the rear surface of the accelerated cooling device An optical fiber radiation thermometer installed at a position corresponding to the scanning radiation thermometer, and a plurality of fiber optic radiation thermometers installed at arbitrary intervals in the line width direction at a position corresponding to the scanning radiation thermometer. Actual analysis means, wherein a material guarantee facility steel plate which comprises a means for determining the temperature distribution of the entire steel sheet from the measured steel sheet temperature at each temperature measurement means.

  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 plurality of spot type radiation thermometers on the front surface of the finish rolling mill and a spot type radiation on the rear surface of the accelerated cooling device. The quality assurance of the thick steel plate according to the first invention, wherein the thermometer and the scanning radiation thermometer each comprise a plurality of high temperature range measurement thermometers and low temperature range measurement thermometers Equipment.

  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 material assurance equipment for thick steel plates according to the second invention, comprising a plurality of low temperature range measuring thermometers for measuring a temperature range of 50 ° C. or more and 300 ° C. or less.

  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. front of the finishing 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 front surface of the finish rolling mill means that a thermometer is installed at a location closer to the finish rolling mill than other equipment in the immediate vicinity of the finish rolling mill. The same applies to the acceleration cooling device.

  The spot-type radiation thermometer is disposed above the upper surface side of the transport line and on the front surface of the finish rolling mill and the rear surface of the acceleration cooling device.

A single spot-type radiation thermometer (7a) to be installed on the front surface of the finish rolling mill may be used. Compared to the case of a single thermometer, it can prevent the mill from stopping when the thermometer is abnormal, and can improve the reliability of the measured temperature when manufacturing mass-produced 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 when a thermometer is provided on either the front surface or the rear surface 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 controlled 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 finish rolling 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 types of thermometers for high temperature measurement and low temperature measurement. A thermometer should be used.

  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, since the steel plate temperature measured at the rear of the accelerating cooling device has a large effect on the material, it is necessary to perform temperature measurement in the width direction of the steel plate to guarantee the material uniformity by the temperature uniformity of the entire steel plate. is there.

Accordingly, the scanning radiation thermometer is installed on the rear surface (6c, 6d) of the acceleration cooling device so as to scan the width direction of the steel plate above the upper surface side of the transport line. 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. As a result, mutual check of abnormality detection of the thermometer becomes 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. Since the lower surface side of the transfer line is in an environment filled with various cooling water, water vapor, etc., install a normal spot type radiation thermometer or scanning radiation thermometer near the rolling mill and near the lower surface side of the hot steel sheet. However, it is difficult to measure temperature accurately for a long time. 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 optical fiber radiation thermometer is installed on the lower surface side of the transfer line corresponding to the spot type radiation thermometer in front of the finishing mill. Further, the spot radiation thermometer located on the rear surface of the acceleration cooling device on the upper surface side of the transport line is also installed on the lower surface side of the corresponding transport line across the transport line.

  Further, an optical fiber radiation thermometer is installed along the scanning direction of the scanning radiation thermometer at a position on the lower surface side of the corresponding transportation line across the transportation line with the installation position of the scanning radiation thermometer located on the rear surface of the acceleration cooling device. Multiple units are installed.

  As the number of installed fiber optic thermometers increases, the temperature distribution in the width direction can be 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 assurance equipment for a thick steel plate according to the present invention provided with the above-described steel plate temperature measuring means, and FIG. 2 shows a flow of temperature information transmission according to the present invention.

  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, 6c and 6d are scanning type radiation thermometers, 7a is installed in the immediate vicinity of the finishing mill, and during rolling, the control rolling start temperature and the rolling finishing temperature are measured and the data Is sent to the control rolling start temperature / finishing temperature collection PC11. 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 are used for temperature control of the accelerated coolant, and 7d and 6d are used for temperature control of the direct quenching material.

  8c, 8d, and 9a are optical fiber radiation thermometers, 9a measures the temperature in the length direction of the steel plate lower surface on the finishing mill entry side, 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 is used for temperature control of the accelerated coolant and 8d is used for direct quenching.

  Next, the flow of transmission of steel plate temperature information measured by each thermometer 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 and lower surface temperature information measured by the spot-type radiation thermometer 7a installed in front of the finishing mill is sent to the control rolling start temperature / finishing temperature collection PC 11 via the upper surface temperature collecting PC 15a and the lower surface temperature collecting PC 16a. Further, rolling temperature management such as control rolling start temperature and rolling finishing temperature, and management of temperature distribution in the length direction are performed.

  Steel plate upper surface temperature information measured by spot type radiation thermometers 7c and 7d and scanning radiation thermometers 6c and 6d installed on the rear surface of the acceleration cooling device 5, and steel plate lower surface temperature measured by optical fiber radiation thermometers 8c and 8d. The 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 PC 11 and the cooling stop temperature collection PC 13 are respectively composed of upper surface temperature collection PCs 15a and 15c and lower surface temperature collection PCs 16a and 16c. Each 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 entrance side and the accelerated cooling device exit side is grasped, the material is judged from a specific threshold value, temperature tolerance, material model, etc. Outputs information on the cut-out part that can secure the desired material.

  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 6c, 6d Scan type radiation thermometer 7a, 7c, 7d Spot type radiation thermometer 8c, 8d, 9a Optical fiber radiation thermometer 11 Control rolling start temperature and 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 downstream 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. The temperature assurance means is provided on the rear surface of the accelerated cooling device and the spot type radiation thermometer installed on the front surface of the finishing mill above the upper surface side of the thick steel plate production line. Installed at the position corresponding to the spot type radiation thermometer on the front side of the finishing rolling mill and the rear surface of the accelerated cooling device on the lower surface side of the thick plate production line and the spot type radiation thermometer and scanning radiation thermometer to be installed Optical fiber radiation thermometers and a plurality of fiber optic radiation thermometers installed at arbitrary intervals in the line width direction at positions corresponding to the scanning radiation thermometers, and the temperature performance analysis means The material guarantees equipment steel plate which comprises a means for determining the temperature distribution of the entire steel sheet from the measured steel sheet temperature at each temperature measurement means.   The temperature measuring means installed on the upper surface side of the thick steel plate production line includes a plurality of spot-type radiation thermometers on the front surface of the finishing mill, and a spot-type radiation thermometer and scanning radiation on the rear surface of the accelerated cooling device. The material guarantee equipment for thick steel plates according to claim 1, wherein each of the thermometers 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 that measures 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. The material guarantee equipment for thick steel plates according to claim 2, comprising a plurality of units with a low temperature range measuring thermometer for measuring the temperature range of the steel plate.

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