JP2010179308A - Quality assurance system for thick steel plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a quality assurance system for a thick steel plate which enables operation control for improving the uniformity of a material in the plate thickness direction of a steel plate and on the surfaces of the steel plate. <P>SOLUTION: The quality assurance system has a temperature measuring means for measuring the temperature of the steel plate and a temperature result analyzing means for analyzing the measured temperature of the steel plate, provided on a steel plate manufacturing line which is provided with a finishing mill and an accelerated cooling device installed in the downstream side of the finishing mill, wherein the temperature measuring means is installed above on the side of the top surface of the steel plate manufacturing line and composed of a spot type radiation thermometer which is installed in the front of the finishing mill and spot type radiation thermometers and scanning type radiation thermometers which are installed in the rear of the finishing mill and in the front and the rear of the accelerated cooling system, and the temperature result analyzing means is composed of a means for determining the temperature distribution of the whole steel plate from the measured temperature of the steel plate, which is measured by 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 start temperature of accelerated cooling, and the cooling stop temperature, various measuring methods for measuring the steel plate temperature with high accuracy and various cooling facilities with a thermometer arrangement have been proposed. ing.

  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 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.

  A thick steel plate tends to have a non-uniform temperature distribution in the thickness direction or in the plate surface by a continuous heating furnace, a descaling device, a cooling facility, 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, a large number of nonconformities may occur.

  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. The upper direction of the material passing direction (Fig. 1) 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 material guarantee facility for thick steel plates equipped with results analysis means,
The temperature measuring means is installed on the upper surface side of the thick steel plate production line, and is installed on a spot type radiation thermometer installed on the front surface of the finishing mill, on the rear surface of the finishing mill, and on the front and rear surfaces of the accelerated cooling device. It comprises a spot type radiation thermometer and a scanning type radiation thermometer, and the temperature performance analysis means comprises means for obtaining the temperature distribution of the entire steel sheet from the steel sheet temperature measured by each temperature measurement means. This is a quality assurance facility for steel sheets.

  In the second aspect of the invention, one or more spot type radiation thermometers are further added to the front and rear surfaces of the finishing mill, and a spot type radiation thermometer and a scanning type radiation thermometer are respectively provided on the rear surface of the accelerated cooling device. A plurality of units are installed, and the plurality of units are each composed of a high temperature range measurement thermometer and a low temperature range measurement thermometer.

  A third aspect of the invention is a spot-type radiation thermometer and a scanning radiation thermometer arranged 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 is right after rolling, it is possible to prevent the occurrence of mass nonconformity by controlling the temperature of the subsequent steel plates, 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 step of the 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 radiation thermometer is used, and a process computer (hereinafter referred to as a PC) is used to collect temperatures measured by a plurality of thermometers.

  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 and rear surfaces of finish rolling mill and Thermometers will be installed as front and back surfaces of the accelerated cooling device.

  In the present invention, the installation of a thermometer on the front (rear) surface of the finish rolling mill means that the thermometer is installed closer to the finish mill than other equipment in the front (rear) direction of the finish mill. Means. The same applies to the acceleration cooling device.

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

  The spot type radiation thermometers (7, 7a) installed on the front and rear surfaces of the finish rolling mill are basically installed in a single number, but it is more preferable to install a plurality of spot type thermometers because it is possible to perform mutual check of thermometer abnormality detection. This is because it is possible to prevent the mill from being stopped when a thermometer is abnormal as compared with the case of one thermometer, or to improve the reliability of the measured temperature when manufacturing a line pipe material to be mass produced. . The installation positions of the plurality of units are not particularly defined, but are desirably arranged in the transport direction.

  The spot type radiation thermometers (7b, 7c, 7d) installed on the front and rear surfaces of the accelerated cooling device have a single front surface, and the rear surface has two types of thermometers, a high temperature region measurement thermometer and a low temperature region measurement thermometer. Is 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 below 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) are installed in this order from the machine side of the acceleration cooling device 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 rolling finishing temperature measured on the rear surface of the finishing mill and the steel plate temperature measured on the front and rear surfaces of the accelerated cooling device have a large effect on the material. It is necessary to guarantee the uniformity of the material by the uniformity of temperature.

Accordingly, the scanning radiation thermometer scans the rear surface (6a) of the finishing mill and the front and rear surfaces (6b, 6c, 6d) of the accelerated cooling device in the width direction of the steel plate above the upper surface side of the transport line. Install as follows. This is because the entire surface temperature can be measured by moving the steel sheet in the length direction by installing the width direction scanning type. 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.

  FIG. 1 shows an embodiment of the outline of the material guarantee facility for a thick steel plate according to the present invention provided with the above-described steel plate temperature measuring means.

The thick steel plate production line includes a heating furnace 1, a finishing 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 located between the finishing mill 2 and the CR shower 4. Indicates.
6a, 6b, 6c and 6d are scanning radiation thermometers, 6a measures the temperature distribution in the width direction and length direction of the steel sheet surface immediately after finish rolling, and the data is sent to the finish temperature collection PC11 as shown in FIG. Sent. 6b is installed on the entrance side of the acceleration cooling device, measures the temperature distribution in the width direction and the length direction of the steel sheet surface immediately before the acceleration cooling, and the data is sent to the cooling start temperature collection PC12. 6c and 6d are installed on the exit side of the accelerated cooling device, 6c is a thermometer for high temperature region measurement, and 6d is a thermometer for low temperature region measurement, both of which are the width direction and length of the steel sheet surface 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. 6c is used for temperature control of the accelerated coolant, and 6d is used for direct quenching material temperature control.

  Next, steps in which the steel plate temperature information measured by each thermometer is sent to the PC will be described with reference to FIG. 11 is a control rolling start temperature, finishing temperature collection PC, 12 is a cooling start temperature collection PC, 13 is a cooling stop temperature collection PC, and 14 is a temperature performance analysis PC.

  The steel plate temperature information measured by the spot type radiation thermometers 7 and 7a installed on the front and rear surfaces of the finishing mill and the scanning radiation thermometer 6a installed on the rear surface of the finishing mill is controlled rolling start temperature and finishing temperature. Rolled temperature management such as rolling temperature, controlled rolling start temperature, end temperature, etc., and management of surface temperature distribution in the width direction and length direction of the steel sheet immediately after rolling measured by the scanning radiation thermometer 6a are performed. Is called.

  Steel plate temperature information measured by the spot-type radiation thermometer 7b and the scanning radiation thermometer 6b installed on the front surface of the accelerated cooling device 5 is sent to the cooling start temperature collection PC 12, and the steel plate temperature management before the accelerated cooling start, The temperature distribution in the steel plate width and length direction is managed.

  The steel plate temperature information measured by the spot type radiation thermometer 7c and the scanning type radiation thermometers 6c, 6d installed on the rear surface of the accelerated cooling device 5 is sent to the cooling stop temperature collecting PC 13 for accelerated cooling stop temperature management, steel plate The temperature distribution in the width and length directions is managed.

  Subsequently, the steel plate temperature information collected in the control rolling start temperature, the finishing temperature collection PC11, the cooling start temperature collection PC12, and the cooling stop temperature collection PC13 is sent to the temperature performance analysis PC14.

  In actual machine production, operation management temperature (controlled rolling start temperature, steel plate finishing temperature, cooling start temperature, cooling stop temperature obtained from spot type radiation thermometers 7, 7a, 7b, 7c) range and temperature performance analysis PC 14 are incorporated. By comparing the actual temperature measurement results and carrying out quality judgment, the quality of the entire steel sheet is guaranteed.

  In addition, the temperature performance analysis PC 14 grasps the entire temperature of the finishing mill entry / exit side and the accelerated cooling device entry / exit side, determines the material from a specific threshold, a temperature tolerance, a material model, etc., and the desired material from the large plate The information of the cut-out part that can be secured is output.

  Further, by controlling the amount of water in the accelerated cooling device in the steel plate width direction and the steel plate longitudinal direction from the temperature distribution in the steel plate width direction and the steel plate longitudinal direction, shape defects and material defects due to uneven cooling can be reduced.

  According to the present invention, the material test rejection rate is reduced by about 30% compared to the conventional case, the warp correction time is reduced by about 20%, and the steel plate shape defect is suppressed by about 10%.

DESCRIPTION OF SYMBOLS 1 Heating furnace 2 Finish rolling mill 3 Steel plate 4 CR shower 5 Accelerated cooling device 6a, 6b, 6c, 6d Scan type radiation thermometer 7, 7a, 7b, 7c Spot type radiation thermometer 11 Control rolling start temperature, finishing temperature collection PC
12 Cooling start temperature collection PC
13 Cooling stop temperature collection PC
14 Temperature performance analysis 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. A material guarantee facility for thick steel plates,
The temperature measuring means is installed on the upper surface side of the thick steel plate production line, and is installed on a spot type radiation thermometer installed on the front surface of the finishing mill, on the rear surface of the finishing mill, and on the front and rear surfaces of the accelerated cooling device. It comprises a spot type radiation thermometer and a scanning type radiation thermometer, and the temperature performance analysis means comprises means for obtaining the temperature distribution of the entire steel sheet from the steel sheet temperature measured by each temperature measurement means. Steel sheet quality assurance equipment.   One or more spot type radiation thermometers are further added to the front and back surfaces of the finishing mill, and a plurality of spot type radiation thermometers and scanning radiation thermometers are installed 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 plurality of units includes a high temperature range measurement thermometer and a low temperature range measurement thermometer.   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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