JP4682614B2 - H-section steel quality judgment method - Google Patents

Description

The present invention relates to a method for determining the quality of H-section steel , and more particularly to a method for collecting temperature data for quality control from the surface temperature distribution in the width direction of H-section steel after hot rolling .

  In many cases, the quality judgment such as the strength of the steel material that has been hot-rolled is performed using a temperature measurement value. For example, in the manufacture of steel materials such as thick plates and H-section steel, water cooling is performed after hot finish rolling, and then the temperature is measured. If the measured value is within an allowable range, it is determined that the quality is good. Yes. In the thick plate, in order to make all the portions in the plate width direction excluding the outermost edge a quality control target, a temperature distribution measurement in the plate width direction is performed using a radiation thermometer. For H-section steel, the temperature distribution of the flange part that guarantees strength is measured, and the temperature of the representative part, for example, the part inside the flange width ¼ from the flange end (hereinafter referred to as the quarter part) is determined from the temperature distribution. We are seeking quality control.

  From the temperature distribution data measured continuously, a threshold is set as shown in FIG. 3, the rising and falling portions of the temperature data are regarded as both ends of the hot steel material, and the temperature data collected during that time is the temperature distribution. It is common to recognize as For example, the temperature of the quarter portion is data in an order corresponding to 1/4 of the total number of temperature data.

  In H-shaped steel, when a thin web is cooled first and the temperature difference from the flange becomes extremely large, a web wave is generated. Since it becomes impossible to ship as a product when it becomes like this, in order to prevent the expansion of a temperature difference, the fillet part which is the outer center of a flange, ie, the base of a web, may be cooled especially intensively. In such a case, the temperature distribution in the width direction of the flange has a concave shape as shown in FIG.

  In temperature measurement with a radiation thermometer, it takes a certain amount of time for the temperature response to rise and fall, so there is a sudden temperature change at the edge, that is, the temperature rise from the part without steel to the steel edge, or the steel. The fall of the temperature from the end part to the part where there is no steel material cannot be accurately captured. Therefore, the rising and falling portions of the end temperature are measured relatively wide. In such a case, for example, the flange temperature distribution of the H-shaped steel after cooling the fillet with water becomes concave as shown in FIG. 3, but the quarter portion is positioned outside the actual position and the temperature is increased from the actual position. There was a problem of recognizing.

  If the measured value measured higher than the actual value does not fall within the allowable range, the portion was determined to be defective in temperature, cut out, and subjected to a material test such as a tensile test. When performing a material test, the yield of the product deteriorates, and there is a problem that the product stays in the warehouse until the result is obtained. When the amount of accumulated material increases, there has also been a problem that a situation occurs in which the rolling operation itself must be stopped.

  As described above, it is often determined that the temperature is defective because the position for recognizing the temperature is shifted. However, even if a material test is performed, there is often no problem with the actual strength. Since the accuracy of the temperature determination is poor, many unnecessary material tests are performed, and there is a problem that the yield is reduced and the cost is increased.

  On the other hand, a measure to widen the allowable temperature range is also conceivable, but there is a problem because the case where the temperature actually deviates from the allowable temperature range is missed. By the way, the present inventors have clarified that the tendency of the radiation thermometer to measure the end portion relatively wide is different depending on the distance from the thermometer. Even if the left and right flange cooling of the H-shaped steel is exactly the same and the same temperature distribution is obtained, the measured value will be different if the measurement distance is different. If this happens, the variation in the correspondence between temperature and material will increase, so the temperature tolerance range will be narrowed so that parts where the material exceeds the tolerance range will not be overlooked. I had to do many material tests.

The present invention has been made in order to solve such problems, and performs high-accuracy quality determination by taking in the temperature of an appropriate determination portion from the surface temperature of the H-shaped steel after hot rolling. It is an object of the present invention to provide a method for judging the quality of H-section steel that makes it possible.

The quality determination method of the H-section steel according to the present invention measures the flange width direction temperature distribution of the H-section steel after hot rolling with a radiation thermometer, recognizes the flange end from the temperature distribution, and determines the temperature determination position. This is a method for determining the quality of the H-section steel based on the temperature data at the temperature determination position, and the deviation between the quality control point that guarantees the strength of the actual H-section steel product and the temperature determination position is reduced. Thus, a temperature threshold value for recognizing the position of the temperature determination position from the flange end or the flange end with respect to the measured flange width is set according to the distance between the radiation thermometer and the flange .

In the method for judging the quality of the H-section steel according to the present invention, in the range of 3 to 15% from the position in the flange width direction of the temperature distribution to the inside in the width direction, corresponding to the position in the flange width direction of the quality control point, The temperature determination position is set according to the distance between the radiation thermometer and the flange.

According to the quality determination method for the H-section steel according to the present invention, the temperature threshold value for recognizing the flange end is set such that the temperature threshold value increases as the distance increases, according to the distance between the radiation thermometer and the flange. Change to be .

The method for judging the quality of the H-section steel according to the present invention comprises measuring the temperature distribution in the flange width direction on both the left and right sides of the H-section steel after hot rolling at the same time, Depending on the distance, the quality of both surfaces of the flange is determined by any of the above methods .

The method for judging the quality of H-section steel according to the present invention is a facility in which two or more lines carrying the H-section steel after hot rolling are parallel to each other. When determining the quality by measuring the temperature distribution at the same time, the quality of both surfaces of the flange is determined by one of the above methods according to the distance between the left and right sides of the flange and the radiation thermometer .

According to the present invention, the surface temperature distribution in the width direction of the H-shaped steel after hot rolling is measured with a radiation thermometer, and temperature data is collected in consideration of the output characteristics of the radiation thermometer in the surface temperature distribution. Since a point to be performed (that is, a temperature determination position) is obtained and quality determination is performed based on the temperature of the sampling point (temperature determination position), high-accuracy quality determination is possible and productivity is improved. .

  FIG. 1 is a configuration diagram of an H-section steel manufacturing facility to which a steel quality determination method according to an embodiment of the present invention is applied, and FIG. 2 is a relative view of the H-section steel and thermometer A and thermometer B. It is explanatory drawing which showed various positional relationships. In this manufacturing facility, a rough rolling mill 10, a cooling facility 11, a finish rolling mill 12, and a cooling facility 13 are arranged in series. A pair of finish entry side thermometers 21 and 22 are arranged on the entry side of the finishing mill 12, and the temperature for measuring the surface temperature distribution of the flange of the H-section steel 20 on the exit side of the cooling facility 13. A meter A23 and a thermometer B24 are arranged. As these thermometers 21 to 24, radiation thermometers are used. As shown in FIG. 2, the thermometer A23 and the thermometer B24 look into the left and right flanges of the H-section steel 20 on the table roller 14 from narrow slits (not shown) provided in the guide 15, respectively. And measure the temperature distribution in the flange width direction.

  In the production facility of FIG. 1, the H-shaped steel is roughly rolled by the roughing mill 10, cooled by supplying cooling water to the outer surface of the flange by the cooling facility 11, and further finish-rolled by the finishing mill 12, In addition, cooling water is supplied to the outer surface of the flange by the cooling equipment 13 to be cooled. Then, on the downstream side of the cooling facility 13, cutting is performed by a hot sawing machine (not shown).

  The temperature distribution in the width direction on both sides of the flange is measured by a pair of finish-side thermometers 21 and 22, a thermometer A23, and a thermometer B24 before finish rolling by the finish mill 12 and after water cooling by the cooling equipment 13, respectively. . The thermometers 21 to 24 continuously scan. When an instruction higher than a certain temperature (threshold value) is output, the thermometer 21-24 recognizes the material and recognizes continuously obtained temperature data as a temperature distribution. Hereinafter, this threshold value is simply referred to as a temperature threshold value. From this temperature distribution measurement, for example, temperature data of the temperature distribution as shown in FIG. 3 is obtained. Each output (temperature data of the temperature distribution in the width direction of the flange) of finishing input side thermometers 21 and 22, thermometer A23 and thermometer B24 is taken into computer 25, and processing such as quality judgment of H-section steel is performed. .

  The computer 25 determines the temperature from the temperature data of the temperature distribution in the width direction of the flange from the thermometer A23 and the thermometer B24 as described in detail in the embodiments described later (see the embodiments 1-3 described later). The temperature at the position is extracted and the quality of the steel is evaluated based on the temperature. How the temperature determination position of the H-section steel is specified will be described in Examples 1 to 3 described later. In the present invention, the quality control point means a point (quarter part) that guarantees the actual product material. The temperature determination position is a position (part) for collecting temperature data processed as the temperature at the actual quality control point, and is determined in consideration of the output characteristics of the radiation thermometer. For this reason, it changes with the measurement conditions by a radiation thermometer.

  As an embodiment of the present invention, after hot finish rolling by the finishing mill 12, cooling water is supplied to the outer surface of the H-shaped steel having a web height of 700 mm, a web thickness of 9 mm, a flange width of 200 mm, and a flange thickness of 22 mm by the cooling equipment 13. Then, the case where the temperature distribution of both surfaces of the flange is measured by the thermometer A23 and the thermometer B24 on the transfer line will be described.

  In the H-section steel manufacturing facility shown in FIG. 1, the relative positional relationship between the thermometers A23, B24 and the H-section steel is as shown in FIG. 2, and the measurement distance is 2 m for the thermometer A23. Thermometer B24 was 6 m. Each of the temperature distributions in the flange width direction, that is, the vertical direction in the example of FIG. 2 is measured by looking through the flange surface from a narrow slit (not shown) provided in the guide 15.

  Comparative Example 1 is a conventional technique for setting the temperature threshold to 350 ° C., and Examples 1 to 3 are examples to which the present invention is applied. In Example 1, the temperature threshold value was set to 450 ° C. in the case of measuring with the farther thermometer B24. In Example 2, the temperature determination position of the temperature distribution A by the thermometer A23 was 30% inside the flange end, and the temperature determination position of the temperature distribution by the thermometer B24 was 35% inside the flange end. In Example 3, processing was performed by recognizing the temperature determination position as an intermediate position between the temperature maximum position and the temperature minimum position in the concave temperature distribution.

In any case, after rough rolling and finish rolling, spray cooling is performed on the width of the flange central portion 160 mm in the cooling facilities 11, 13, and both the left and right sides (the thermometers A and B sides) of the flange are center portions in the width direction. The case where the surface temperature is 600 ° C. is compared. The temperature judgment position, which is the sampling point of temperature data, is the upper and lower quarters (or positions with corrections) Q _A1 , Q _A2 , Q _B1 , Q _{B2 on} the left and right sides of the flange (the thermometers A and B sides). The temperature of the four quarters is extracted from the temperature distribution measured by each thermometer and output. The allowable range of temperature for obtaining the target material (strength and elongation) in the quarter part is, for example, 560 to 680 ° C., and if the measured value does not fall within the allowable range, it is recognized as a temperature defect determination material, A part of the product (quarter part) was cut out and a material test was conducted.

In Comparative Example 1, the temperature distribution measured by the radiation thermometer has a relatively wide range of rising and falling edge temperatures, and the temperature maximum position is on the inner side than the actual temperature. This tendency was particularly strong in the temperature distribution B measured by the farther thermometer B23. The temperatures of Q _A1 , Q _A2 , Q _B1 , and Q _B2 , which are the temperature distribution and the temperature determination position (the temperature determination position in Comparative Example 1 is the same as the quota portion), are as shown in FIG. That is, Q _A1 and Q _A2 were 640 ± 30 ° C. (hereinafter, “±” represents a variation within which 90% of the measured values are subtracted), whereas Q _B1 and Q _B2 were measured to be 670 ± 30 ° C. There were many parts exceeding 680 ° C., and the temperature defect judgment was 40%. Until the material test result is known, it stays in the product warehouse, resulting in the problem of logistics disruption. Of the materials with defective temperature, only 2.5% were actually defective, and quality control was extremely inefficient, even though it prevented the shipment of defective materials. Become.

In Example 1, the temperature distribution A was not different from that in Comparative Example 1. However, since the temperature threshold value of the thermometer B24 was increased to 450 ° C., the rising and falling portion in the temperature distribution B was slightly reduced. The temperatures of Q _A1 , Q _A2 , Q _B1 , and Q _B2 , which are the temperature distribution and the temperature determination position (the temperature determination position of Comparative Example 1 matches the quarter portion), are as shown in FIG. That is, Q _A1 and Q _A2 were 640 ± 30 ° C., whereas Q _B1 and Q _B2 were measured to be 655 ± 30 ° C. The part exceeding 680 ° C. was somewhat reduced, and the temperature defect judgment was reduced to 10%. The defective percentage of the material was 10%, and the quality control efficiency was better than that of Comparative Example 1.

In Example 2, the temperature determination position in the temperature distribution A was processed as a position 30% from the end, and the temperature determination position in the temperature distribution B was processed as a position 35% from the end. Therefore, the temperature determination position of Example 2 is located inside the quarter portion. FIG. 4C shows the temperature distribution and the temperatures of Q _A1 , Q _A2 , Q _B1 , and Q _B2 that are the temperature determination positions. That is, Q _Al , Q _A2 , Q _B1 , and Q _B2 were measured as 630 ± 30 ° C. Only in rare cases was the temperature measured above 680 ° C., and the temperature defect judgment decreased to 2%. The median failure rate was 50%, and the efficiency of quality control was dramatically improved as compared with Comparative Example and Example 1. Since the number of unnecessary material tests has been reduced, yields have been improved and costs have been reduced.

In Example 3, both the temperature distributions A and B were processed with the temperature determination position as an intermediate position between the maximum position and the minimum position, and the temperature at the temperature determination position as the temperature at the intermediate position. The temperature distribution and temperature of Q _A1 , Q _A2 , Q _B1 , and Q _B2 that are temperature determination positions are as shown in FIG. That is, Q _A1 , Q _A2 , Q _B1 , and Q _B2 were measured as 30 ± 630 ° C. Similar to Example 2, the temperature defect determination decreased to 2%. The median failure rate was 50%, and the number of unnecessary material tests was reduced as compared with Comparative Example and Example 1. Therefore, the yield was improved and the cost could be reduced.

  In Examples 1 to 3, since the temperature defect determination was 10% or less, no disruption of physical distribution occurred.

  In the above embodiment, the temperature distribution on both sides of the flange of the H-shaped steel was measured with two radiation thermometers with different distances, and the method for managing the quality was shown. However, the present invention is not limited to this. Absent. For example, even when only one side of the flange is measured, or even when two thermometers are installed at the same distance, there is a difference in degree if Examples 1 to 3 described later are applied. High quality control is performed.

  In the second embodiment, the temperature determination position (definition point) for performing quality determination on the temperature distribution is corrected to 5 to 10% of the flange width from the actual quality control point (quarter part) that guarantees the material. It may be in the range of 3 to 15% of the flange width. When the measurement distance is shorter than the embodiment of the present invention, for example, 1.5 m, the ratio may be reduced to 3%. Incidentally, if the correction is smaller than 3%, the meaning of the correction is not made, and the effect of the present invention is hardly obtained, and if it exceeds 15%, it becomes indistinguishable from the central temperature, so the meaning of the present invention is not made.

  In the third embodiment, the temperature determination position is obtained by interpolation between the maximum position and the minimum position of the temperature distribution. However, the temperature of the quality control point is directly obtained from the maximum value and the minimum value of the temperature distribution by interpolation. Also good. Furthermore, it may be applied in the manufacture of shape steels other than H-section steel, and may also be applied in the manufacture of thick plates. In addition, each of the above examples is an example of one transfer line, but the present invention is similarly applied to an installation having two or more transfer lines.

  FIG. 5 is an explanatory diagram showing the relationship between the H-section steel, the thermometer A, and the thermometer B when two transport lines are provided. In the example of FIG. 5, for example, the H-section steel 20 is provided with two transport lines (table rollers 14 and 14 a) on the downstream side of the cooling facility 13, and the H-section steel 20 cooled by the cooling facility 13 is any one. Assuming a configuration that is sent to one of the transfer lines, the temperature distribution in the width direction of the flange of the H-section steel 20 of one of the transfer lines is determined by the thermometer A23 and the thermometer B24 in the slits of the guides 15 and 15a ( (Not shown). Based on the temperature data of the temperature distribution in the width direction of the flange from the thermometer A23 and the thermometer B24, the temperature of the quality control point is extracted, and the quality evaluation of the steel material is performed based on the temperature. 1 to Example 3.

Schematic of the manufacturing equipment of H section steel. Explanatory drawing which showed the example of the relative relationship between H-section steel and thermometers A and B. The figure which showed the temperature distribution of the width direction of the flange of H-section steel. The figure showing the temperature distribution data and temperature judgment position of the width direction of the flange of H-section steel. Explanatory drawing which showed the other example of the relative relationship between H-section steel and thermometers A and B.

Explanation of symbols

10 coarse rolling mill, 11 cooling facility, 12 finish rolling mill, 13 cooling facility, 15 guide,
20 H-section steel, 21, 22 Finish entry side thermometer, 23 thermometer A, 24 thermometer B.

Claims (5)

The temperature distribution in the flange width direction of the H-shaped steel after hot rolling is measured with a radiation thermometer, the end of the flange is recognized from the temperature distribution, the temperature determination position is obtained, and H based on the temperature data at the temperature determination position A method for determining the quality of a shape steel,
The temperature judgment position relative to the measured flange width according to the distance between the radiation thermometer and the flange so that the deviation between the quality control point that guarantees the strength of the actual H-shaped steel product and the temperature judgment position becomes small. A method for determining the quality of H-section steel, comprising setting a temperature threshold value for recognizing the position from the flange end of the flange or the flange end . Corresponding to the position in the flange width direction of the quality control point, the temperature judgment position is set in the range of 3 to 15% in the width direction from the position in the flange width direction of the temperature distribution between the radiation thermometer and the flange. 2. The method for judging the quality of H-section steel according to claim 1, wherein the quality is determined according to a distance . The temperature threshold value for recognizing an end of the flange is changed according to the distance between the radiation thermometer and the flange so that the temperature threshold value becomes higher as the distance increases. A method for judging the quality of the H-section steel according to 1. When measuring the temperature distribution in the flange width direction on both the left and right sides of the H-shaped steel after hot rolling at the same time, depending on the distance between the left and right flanges and the radiation thermometer, any one of claims 1 to 3 A method for judging the quality of an H-section steel, characterized in that the quality judgment on both sides of the flange is performed by such a method. In equipment where two or more lines carrying H-shaped steel after hot rolling are parallel, when measuring the temperature distribution in the left and right flange width directions of the H-shaped steel from the outside of the line at the same time, A method for judging the quality of an H-section steel, characterized in that the quality judgment of both surfaces of the flange is performed by the method according to any one of claims 1 to 3, in accordance with the distance between the left and right sides of the flange and the radiation thermometer .

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