Method for evaluating stripe height, and method for manufacturing checkered plates.

Abstract

This provides a method for estimating stripe height at a lower cost and with greater safety. [Solution] A checker plate is manufactured by forming an uneven pattern on one side of a steel plate 1 with a rolling roll having an uneven pattern when finishing rolling in tandem hot rolling, and a method for evaluating the checker height, which is the height of the formed uneven pattern, is used when manufacturing the checker plate. The correlation between the reduction ratio at a stand incorporating the rolling roll having the uneven pattern and the checker height is determined in advance, and the checker height of the manufactured checker plate is estimated from the reduction ratio at a stand incorporating the rolling roll having the uneven pattern by referring to the correlation.

Description

Technical Field

[0001] The present invention relates to a technique for manufacturing a patterned sheet by finish rolling using tandem hot rolling. In particular, the present invention relates to a technique for determining the height of the pattern formed by the finish rolling.

Background Art

[0002] The manufacturing of a steel sheet (patterned sheet) having a pattern of unevenness on one side is performed by tandem hot rolling. At that time, a work roll having an uneven pattern is incorporated into the last rolling mill (final stand) for rolling with a tandem rolling mill and rolled. Thereby, a patterned sheet which is a steel sheet having an uneven pattern is manufactured.

[0003] Here, the height of the uneven pattern (pattern height) of the patterned sheet varies depending on the reduction amount of the final stand. Therefore, conventionally, the pattern height of the patterned sheet after the hot rolling is measured, and the reduction amount is adjusted so that the measured value is equal to or greater than the target pattern height (target height).

[0004] For example, in the technique described in Patent Document 1, the thicknesses of the pattern portion (convex portion) and the thin portion (concave portion) in the patterned sheet rolled by a tandem hot rolling mill are continuously measured online by a thickness gauge. Then, according to the measured value of the thickness of the pattern portion, the roll gap of the previous final rolling stand is changed to control the thickness of the pattern portion to the target thickness. Thereby, according to the measured value of the thickness of the thin portion, the roll gap of the final rolling stand is changed to control the thickness of the thin portion to the target thickness. However, in Patent Document 1, on the premise, the thicknesses of the convex portion and the concave portion of the patterned sheet after the finish rolling are measured separately, and the control is performed by adjusting the actual results to match the target.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] In conventional control methods, the height of the checkered pattern of the formed checkered plate is measured at the exit of the tandem rolling mill. Then, the rolling position (roll gap) of the final stand or the stand before the final one is adjusted to match the measured height to the guaranteed value. However, in order to determine the actual checkered pattern height, it is necessary to measure it using a thickness gauge that can distinguish and measure the convex and concave parts of the uneven pattern, as described in Patent Document 1. Alternatively, it is necessary to measure the checkered pattern height manually. However, measuring with a thickness gauge is expensive and costly.

[0007] Furthermore, manual measurement, depending on the factory layout, means that by the time the checker plate height measurement is complete, several checker plates have already undergone finish rolling. This results in the production of several coils where the reduction position cannot be corrected in time. In addition, hot-rolled steel sheets are at high temperatures, and there are concerns that workers may come into contact with the high-temperature material during measurement, posing a safety risk.

[0008] This invention focuses on the points described above and aims to provide a method for estimating the stripe height at a lower cost and with greater safety. [Means for solving the problem]

[0009] To solve the problem, one aspect of the present invention is a method for manufacturing a checker plate by forming an uneven pattern on one side of a steel plate with a rolling roll having an uneven pattern when finishing rolling in tandem hot rolling, and for evaluating the checker height, which is the height of the formed uneven pattern, during the manufacturing of the checker plate, wherein the correlation between the reduction ratio at a stand incorporating the rolling roll having the uneven pattern and the checker height is determined in advance, and the checker height of the manufactured checker plate is estimated from the reduction ratio at the stand incorporating the rolling roll having the uneven pattern by referring to the above correlation, and this is a checker height evaluation method. [Effects of the Invention]

[0010] According to an aspect of the present invention, for example, by calculating the reduction ratio in a stand incorporating a rolling roll having an uneven pattern from the actual rolling load and reduction position, the height of the stripe pattern can be estimated simply and quickly.

[0011] Accordingly, the embodiments of the present invention reduce the risks associated with manual measurement and also have the effect of reducing labor costs that were previously incurred by manually measuring the stripe height. Furthermore, while conventional methods use a thickness gauge capable of distinguishing and measuring uneven patterns to determine the stripe height, the embodiments of the present invention only require a change in the control method, making it possible to control the stripe height at a low cost. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows the processing steps according to an embodiment of the present invention. [Figure 2] This is a schematic diagram illustrating a tandem hot rolling mill according to an embodiment of the present invention. [Figure 3] This diagram shows a textured (striped) pattern. (a) is a plan view, and (b) is a cross-sectional view. [Figure 4] This is a schematic diagram showing the reduction ratio. [Figure 5] This figure shows the variation in reduction ratio and fringe height along the entire length of the coil. [Figure 6] This figure shows the correlation between reduction ratio and stripe height. [Modes for carrying out the invention]

[0013] Next, embodiments based on the present invention will be described with reference to the drawings. As shown in Figure 1, the process for manufacturing checkered plates includes a rolling line S10 (hot finish rolling) and a finishing line S20 (skin pass line).

[0014] <Rolling line S10> The finishing rolling in the hot rolling process is carried out by tandem hot rolling to roll the steel plate to produce a coil composed of striped plates. As shown in FIG. 2, the tandem hot rolling is performed by a tandem hot rolling mill 2 in which a plurality of stands are arranged in parallel along the pass line. In the example shown in FIG. 2, the tandem hot rolling mill 2 itself has seven stands F1 to F7. However, it shows the case of manufacturing the striped plate 1 by rolling at six stands F6 without using the seventh stand F7. In this example, the last stand among the stands actually used for rolling is called the final stand. In the example of FIG. 2, the sixth stand F6 becomes the final stand.

[0015] In the present embodiment, among the stands F1 to F6 used for rolling, as the upper work roll 3 of the work roll (rolling roll) of the final stand F6, a work roll having an uneven pattern is used (see FIG. 4).

[0016] That is, the upper rolling roll 3 of the final stand F6 has a cut for forming unevenness of stripes (see FIG. 3(a)) on the surface of the steel plate 1. The depth of the cut in the rolling roll 3 is deeper than the stripe height t0 formed on the steel plate 1 (see FIG. 3). In FIG. 3, reference numeral 1A indicates the groove portion of the stripe. Corresponding to FIG. 3, the rolling roll 3 has a cut corresponding to the unevenness of the stripes.

[0017] For example, when the guaranteed height guaranteed as a product of the stripe height is 1 mm, considering the rolling reduction by finishing line S20 for adjusting the shape of the steel plate 1, the filling rate of the cut, etc., the cut depth in the rolling roll 3 is, for example, 2.55 mm. Also, as shown in FIG. 3, it is a trapezoidal cut so as to have the shape of the stripe.

[0018] Then, in the present embodiment, by finishing rolling the steel plate 1 with the tandem hot rolling mill 2, the steel plate 1 is manufactured as a striped plate having an uneven pattern on one side (upper surface).

[0019] Here, the target sheet thickness on the rolling line S10 is set higher than the guaranteed height guaranteed as a product in consideration of the rolling reduction on the finishing line S20. For example, when the guaranteed stripe height as a product is 1 mm, for example, the target height on the rolling line S10 is set higher than the guaranteed stripe height such as 1.3 mm.

[0020] In this embodiment, the rolling reduction rate is calculated from the actual load and the rolling reduction position (rolling gap) at the sixth stand F6 incorporating the work roll having the uneven pattern. The rolling reduction rate may be calculated by a known method. As shown in FIG. 4, the rolling reduction rate is expressed as "(exit side sheet thickness t2 - entrance side sheet thickness t1) ÷ entrance side sheet thickness t1" with respect to the final stand.

[0021] Here, as shown in FIG. 5, the value of the actual rolling reduction rate measured along the longitudinal direction fluctuates greatly. Therefore, it is preferable to use the average value of the rolling reduction rate for each predetermined time as the rolling reduction rate used when estimating the stripe height. By using the average value, as shown in FIG. 5, the fluctuation range of the rolling reduction rate used can be suppressed small. In FIG. 5, the average value in units of 0.5 seconds is indicated by dots. As can be seen from FIG. 5, the average value of the rolling reduction rate has a small fluctuation range.

[0022] Further, the average value of the rolling reduction rate of the entire length of the coil (steel sheet 1) may be used as the rolling reduction rate for evaluating the stripe height of the coil (steel sheet 1). In addition, it is not necessary to evaluate the stripe height over the entire length of the coil (steel sheet 1). For example, the stripe height of the coil (steel sheet 1) may be evaluated using the tip position, the intermediate position, and the tail end position of the coil as representative positions. Further, the average value of the representative values of the rolling reduction rate at the tip position, the intermediate position, and the tail end position may be used as the rolling reduction rate for evaluating the stripe height of the coil (steel sheet 1).

[0023] Next, the estimated stripe height is obtained from the obtained rolling reduction rate using the previously obtained correlation between the rolling reduction rate and the stripe height. Then, it is determined whether or not the estimated stripe height is equal to or higher than the target height. This determination is executed in real time during rolling.

[0024] The correlation is determined by statistically processing multiple data points previously obtained regarding "reduction ratio and the stripe height at that reduction ratio" to find the relationship (correlation) between the reduction ratio and the stripe height. The method for determining the correlation can be any conventionally known method. In this case, the stripe height can be, for example, the value at the center in the width direction of the plate, or the average value at several points in the width direction.

[0025] Alternatively, the reduction ratio of the sixth stand may be controlled by referring to the correlation to determine the target reduction ratio corresponding to the target height, so that the target reduction ratio is achieved.

[0026] Then, if it is determined that the estimated stripe height is less than the target height, an alarm is issued to the operator. The alarm may be, for example, an audible alarm or a visual alarm.

[0027] Furthermore, if the estimated stripe height is determined to be less than the target height, the reduction ratio for the next material's rolling will be adjusted to be higher than the current setting. Alternatively, the set load and reduction position (roll gap) of the sixth stand may be changed in real time during the current rolling process to adjust the reduction ratio to be higher.

[0028] <Refined Line S20> Subsequently, the checkered plates produced by the finish rolling process are sent to the finishing line S20 for temper rolling. In this embodiment, the index for the pressure adjustment amount of the finishing line S20 is determined according to the estimated stripe height estimated above.

[0029] For example, if the estimated striation height after finish rolling is lower than the target height for finish rolling, the pressure adjustment amount for the finishing line S20 is set lower than the specified value to ensure that the temper rolling is performed at a pressure adjustment amount that does not result in a striation height below the guaranteed product height. The specified value is, for example, the pressure adjustment amount when the estimated striation height after finish rolling is the target height (1.3 mm). Alternatively, the pressure adjustment amount for the finishing line S20 may be determined according to the estimated striation height after finish rolling, regardless of whether the estimated striation height after finish rolling is lower than the target height for finish rolling.

[0030] In this embodiment, since the estimated stripe height can be evaluated during rolling in the rolling line S10, the pressure adjustment amount of the finishing line S20 can be changed over time. Furthermore, if the estimated stripe height is less than the stripe height guaranteed for the product, it will be considered a defective product.

[0031] (Operation and other functions) The checkered plates are rolled in the hot rolling line S10 and then shipped out through the finishing line S20. The guaranteed groove height of the product after passing through the finishing line S20 is set to 1 mm. In this case, the finishing line S20 measures the groove height and determines whether that groove height is 1 mm (guaranteed groove height) or greater. To meet the guaranteed 1mm stripe height requirement, the rolling line S10 requires, for example, a minimum stripe height of 1.3mm or more.

[0032] After passing through the rolling line S10, it takes, for example, more than three days for the plates to be loaded into the finishing line S20. If it is not possible to check in real time whether the checker plate meets the 1.3 mm requirement when continuously rolling the checker plate in the rolling line S10, there is a concern that a large number of checker plates with a checker height below the guaranteed product level will be produced. As a countermeasure, the striation height has been measured on the rolling line S10 as before.

[0033] However, since the coils after rolling on the S10 rolling line are at a high temperature of over 500°C, measuring their height is a dangerous operation. Furthermore, the coils can only be measured about 5 minutes after passing through the finishing rolling mill. As a result, by the time of measurement, subsequent materials, for example, two coils, have already been rolled. Consequently, there is a possibility of continuously producing checkered plates with checker heights below the guaranteed level.

[0034] In contrast, in this embodiment, it is possible to easily and quickly determine whether or not the guaranteed stripe height is secured in the rolling line S10 in a non-contact and real-time manner.

[0035] Furthermore, when manual measurement was performed, it was only possible to measure the material three coils prior to the material being finished rolling, and corrections to the reduction amount when the striation height was inappropriate had to be made from coils three coils or later. In contrast, according to an embodiment of the present invention, measurement of high-temperature coils immediately after rolling is simplified, and dangerous work has also been reduced.

[0036] Furthermore, while it is possible to accurately measure the stripe height by introducing a high-performance thickness gauge for controlling the stripe height, as in the conventional method, this is expensive. In contrast, according to an embodiment of the present invention, it is possible to estimate and correct the stripe height in real time from rolling results without using an expensive thickness gauge.

[0037] As described above, in this embodiment, the striation height can be estimated based on the actual rolling load and reduction position, making it possible to adjust the reduction amount in real time during rolling at low cost.

[0038] (Examples) Figure 5 shows an example of the variation in reduction ratio and stripe height over the entire length of a coil in a hot finishing line. As shown in Figure 5, the actual reduction ratio fluctuates. Therefore, in this embodiment, it is best to use the average value of the reduction ratio. Figure 2 shows an example where the average value was taken at 0.5-second intervals. As shown in Figure 5, by adopting the average value as the reduction ratio, it is possible to reduce the range of fluctuation in the reduction ratio along the longitudinal direction of the coil.

[0039] The dashed horizontal lines in Figure 5 indicate the threshold reduction ratio corresponding to a stripe height of 1.3 mm, based on a target height of 1.3 mm and referencing the correlation. In the example shown in Figure 5, it can be determined that the fringe height is 1.3 mm or greater along the entire length of the coil.

[0040] Figure 6 is a plot showing the relationship between the stripe height and the final stand reduction ratio. Examples are given for base material thicknesses (thickness after rolling) of 4.5 mm, 3.2 mm, and 2.3 mm. This data was obtained by collecting data on the entire length of the roll, calculating the reduction ratio from the reduction position and load during hot rolling, and using the average reduction ratio. In addition, the striation height was measured at regular intervals on the entry side of the finishing line S20, and the average value was used.

[0041] As can be seen in Figure 6, although there is some variation depending on the thickness of the base material, the stripe height also increases with increasing reduction ratio, confirming a correlation between reduction ratio and stripe height.

[0042] Assuming a minimum guaranteed groove height of 1.3 mm at the exit side of the rolling line S10 (input side of the finishing line S20), Figure 6 shows that in order to satisfy this, the reduction ratio must be 23% or more, regardless of the thickness of the base material. Therefore, by detecting when the reduction ratio falls below 23% over the entire length of the coil, it is possible to change the reduction setting for the next rolled material and adjust the pressure adjustment amount at the finishing line S20.

[0043] (others) This disclosure may also take the following form: (1) A method for manufacturing a checker plate by forming an uneven pattern on one side of a steel plate with a rolling roll having an uneven pattern when finishing rolling in tandem hot rolling, and for evaluating the checker height, which is the height of the uneven pattern formed during the manufacturing of the checker plate, Beforehand, the correlation between the reduction ratio in a stand incorporating the rolling rolls having the above-mentioned uneven pattern and the height of the stripes is determined. By referring to the above correlation, the height of the checkered pattern on the manufactured checkered plate is estimated from the reduction ratio at a stand incorporating the rolling rolls having the above-mentioned uneven pattern. Method for evaluating the height of the striped pattern. (2) The average value of the reduction ratio is used as the reduction ratio when determining the correlation described above, and when estimating the fringe height. The stripe height evaluation method described in this disclosure. (3) As the average value of the reduction ratio mentioned above, the average value of the reduction ratio over the entire length of the steel plate manufactured by rolling shall be used. The stripe height evaluation method described in this disclosure. (4) The longitudinal positions for evaluating the stripe height shall be the leading edge, middle, and trailing edge of the steel plate. The stripe height evaluation method described in this disclosure. (5) A method for manufacturing checkered plates, in which, when finishing rolling by tandem hot rolling, a pattern of unevenness is formed on one side of a steel plate using a rolling roll having an uneven pattern, If the stripe height estimated by the stripe height evaluation method described in this disclosure is determined to be less than the target height, an alarm will be issued. Striped board manufacturing method. (6) A method for manufacturing checkered plates, in which a checkered plate is manufactured by forming an uneven pattern on one side of a steel plate with a rolling roll having an uneven pattern when finishing rolling in tandem hot rolling, The above tandem hot rolling process has a finishing line as a subsequent process, The index for the pressure regulation amount of the finishing line is determined according to the stripe height estimated by the stripe height evaluation method described in this disclosure. Striped board manufacturing method. (7) A method for manufacturing checkered plates, in which a checkered plate is manufactured by forming an uneven pattern on one side of a steel plate with a rolling roll having an uneven pattern when finishing rolling in tandem hot rolling, If the striation height estimated by the striation height evaluation method described in this disclosure is determined to be less than the target height, the setting is changed to increase the reduction ratio in the stand incorporating the rolling rolls with the uneven pattern. Striped board manufacturing method. [Explanation of Symbols]

[0044] 1 Steel plate (striped plate) 2 Tandem hot rolling mill 3. Work roll for forming stripes F6 Final Stand S10 Rolling Line S20 Refinement Line

Claims

1. A method for manufacturing checkered plates by forming an uneven pattern on one side of a steel plate using rolling rolls with an uneven pattern during finish rolling in tandem hot rolling, and for evaluating the checker height, which is the height of the uneven pattern formed during the manufacturing of the checkered plate, Beforehand, the correlation between the reduction ratio in a stand incorporating the rolling rolls having the above-mentioned uneven pattern and the height of the stripes is determined. By referring to the above correlation, the height of the checkered pattern on the manufactured checkered plate is estimated from the reduction ratio at a stand incorporating the rolling rolls having the above-mentioned uneven pattern. Method for evaluating the height of the striped pattern.

2. The average reduction ratio is used as the reduction ratio when determining the correlation mentioned above, and also when estimating the fringe height. The method for evaluating the height of the stripes as described in claim 1.

3. As the average reduction ratio mentioned above, the average reduction ratio of the entire length of the steel plate manufactured by rolling is used. The method for evaluating the height of the stripe pattern as described in claim 2.

4. The longitudinal positions used to evaluate the stripe height are defined as the leading edge, middle, and trailing edge of the steel plate. The method for evaluating the height of the stripes as described in claim 1.

5. A method for manufacturing checkered plates, in which, during finish rolling by tandem hot rolling, a pattern of unevenness is formed on one side of a steel plate using a rolling roll having an uneven pattern, If the stripe height estimated by the stripe height evaluation method described in any one of claims 1 to 4 is determined to be less than the target height, an alarm is sounded. Striped board manufacturing method.

6. A method for manufacturing checkered plates, in which, during finish rolling by tandem hot rolling, a pattern of unevenness is formed on one side of a steel plate using a rolling roll having an uneven pattern, The above tandem hot rolling process has a finishing line as a subsequent process, An index for the pressure adjustment amount of the finishing line is determined according to the stripe height estimated by the stripe height evaluation method described in any one of claims 1 to 4. Striped board manufacturing method.

7. A method for manufacturing checkered plates, in which, during finish rolling by tandem hot rolling, a pattern of unevenness is formed on one side of a steel plate using a rolling roll having an uneven pattern, If the stripe height estimated by the stripe height evaluation method described in any one of claims 1 to 4 is determined to be less than the target height, the setting is changed to increase the reduction ratio in the stand incorporating the rolling roll having an uneven pattern. Striped board manufacturing method.

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