Apparatus and method for measuring the flatness of flat steel

Abstract

To provide a flatness measurement device and flatness measurement method for a flat steel, capable of safely and accurately measuring a flatness in a length direction of a flat steel.SOLUTION: A flatness measurement device 1 for a flat steel measures a flatness in a length direction of flat steel S placed on an upper surface 2a of a surface plate 2. The flatness measurement device 1 comprises: a distance measurement device 10 in which a surface plate height distance meter 13 that measures a distance A to the upper surface 2a of the surface plate 2 and a flat steel height distance meter 14 that measures a distance B to an upper surface Sa of the flat steel S are attached to a measurement device body 11 that moves along the length direction of the flat steel S; and a flatness calculation device 40 that calculates the flatness in the length direction of the flat steel S using the distance A to the upper surface 2a of the surface plate 2 measured with the surface plate height distance meter 13 and the distance B to the upper surface Sa of the flat steel S measured with the flat steel height distance meter 14.SELECTED DRAWING: Figure 1

Description

Technical Field

[0005]

[0001] The present invention relates to a flatness measuring apparatus and a flatness measuring method for flat steel produced by hot rolling.

Background Art

[0002] Regarding the shape, dimensions, tolerances, appearance, and quality of flat steel produced by hot rolling, they are defined by JIS G 3194. This flat steel generally has a rectangular shape with a width of 25 to 200 mm, a thickness of 4.5 to 25 mm, and a length of 7 m or less. The tolerance for flatness in the length direction of this flat steel is also defined by JIS G 3194. Here, the flatness in the length direction of the flat steel refers to the uneven state of the upper and lower surfaces in the length direction of the flat steel. <00管理員000011> Conventionally, when measuring the flatness in the length direction of this flat steel, the flat steel is placed on a surface plate, and visually, the place where the gap between the flat steel and the surface plate is the largest in the length direction is found, and the gap is measured using a "gap gauge", and this measured gap is regarded as the flatness in the length direction of the flat steel.

[0004] In Patent Document 1, when measuring the flatness of a thick steel plate, a plurality of non-contact distance gauges are vertically installed on the lower surface between two conveying rolls on a conveying table, and while moving the thick steel plate on the conveying table, the distance to the lower surface of the thick steel plate is measured at regular intervals in the longitudinal direction by the non-contact distance gauges over the entire surface of the thick steel plate, and from these measurement data and the distance value corresponding to the pass line measured in advance, the strain waveform between the pass line and the thick steel plate is obtained, and a method of performing a strain calculation from this strain waveform is disclosed.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

[0006] However, this conventional method for measuring the flatness of flat steel had the following problems. In other words, the temperature of the flat steel placed on the surface plate can reach up to approximately 300°C. Therefore, if the gap between the flat steel and the surface plate is measured manually using a gap gauge, there is a risk of contact with the hot steel, such as burns.

[0007] Furthermore, even when multiple non-contact distance meters are vertically installed on the underside between two transport rolls in a transport table disclosed in Patent Document 1, and the distance to the underside of the thick steel plate is measured at regular intervals along the longitudinal direction across the entire surface of the thick steel plate using the non-contact distance meters while the thick steel plate is moved on the transport table, there is a risk of contact with the hot flat steel plate by hands or other body parts, which poses a risk of burns and other dangers. Furthermore, in the method of visually finding the point where the gap between the flat steel and the surface plate is largest in the longitudinal direction and measuring that gap using a "gap gauge," it is difficult to visually find the maximum value of the gap along the entire length of the flat steel, and it may not be possible to measure the flatness of the flat steel in the longitudinal direction with high accuracy.

[0008] Therefore, the present invention has been made to solve these conventional problems, and its objective is to provide a flatness measuring device and flatness measuring method for flat steel that can safely and accurately measure the flatness of flat steel in the longitudinal direction. [Means for solving the problem]

[0009] To solve the above problems, one aspect of the present invention provides a flatness measuring device for flat steel, which measures the flatness of flat steel placed on the upper surface of a surface plate in the longitudinal direction, comprising: a distance measuring device having a surface plate height distance meter for measuring the distance to the upper surface of the surface plate and a flat steel height distance meter for measuring the distance to the upper surface of the flat steel attached to a measuring device body that moves along the longitudinal direction of the flat steel; and a flatness calculation device that calculates the flatness of flat steel in the longitudinal direction using the distance to the upper surface of the surface plate measured by the surface plate height distance meter and the distance to the upper surface of the flat steel measured by the flat steel height distance meter.

[0010] Furthermore, another aspect of the present invention relates to a method for measuring the flatness of a flat steel, which measures the flatness of a flat steel placed on the upper surface of a surface plate in the longitudinal direction, wherein the measuring device body of a distance measuring device is attached to a surface plate height distance meter for measuring the distance to the upper surface of the surface plate and a flat steel height distance meter for measuring the distance to the upper surface of the flat steel, and the measuring device body is moved along the longitudinal direction of the flat steel, the distance to the upper surface of the surface plate is measured by the surface plate height distance meter and the distance to the upper surface of the flat steel is measured by the flat steel height distance meter, and the flatness of the flat steel in the longitudinal direction is calculated by a flatness calculation device using the distance to the upper surface of the surface plate measured by the surface plate height distance meter and the distance to the upper surface of the flat steel measured by the flat steel height distance meter. [Effects of the Invention]

[0011] The present invention provides a flatness measuring device and flatness measuring method for steel that can safely and accurately measure the flatness of flat steel in the longitudinal direction. [Brief explanation of the drawing]

[0012] [Figure 1] This is a front view showing a schematic configuration of a flatness measuring device for flat steel according to one embodiment of the present invention. [Figure 2] Figure 1 is a right side view of the flatness measuring device for flat steel. [Figure 3] Figure 1 is a plan view of the flatness measuring device for flat steel. [Figure 4] Figure 1 is a flowchart illustrating the processing flow in the flatness measuring device for flat steel. [Figure 5] This is a diagram illustrating the method for measuring the flatness of flat steel using a flatness measuring device. [Figure 6] This diagram illustrates another example of a method for measuring the flatness of flat steel using a flatness measuring device. [Figure 7] Figure 1 is a front view of an example in which the flatness measuring device for flat steel, shown in Figure 1, is installed on the flatness support section of an automatic conveying device located above the conveying surface of a conveying chain that transports flat steel. [Figure 8] This is a left side view of Figure 7. [Figure 9] This is a plan view of Figure 7. [Figure 10] Figure 7 shows a permanent magnet assembly installed in the automated transport device, illustrating the state before the permanent magnets on the assembly attract the flat steel (after they are released). [Figure 11] Figure 7 shows a permanent magnet assembly installed in the automated transport device, illustrating the state after the permanent magnets on the assembly have attracted the flat steel (before releasing it). [Figure 12] This is a perspective view of a flat steel bar. [Modes for carrying out the invention]

[0013] Embodiments of the present invention will be described below with reference to the drawings. The embodiments shown below are illustrative examples of devices and methods for realizing the technical concept of the present invention, and the technical concept of the present invention is not limited to the following embodiments in terms of the material, shape, structure, arrangement, etc. of the components. Also, the drawings are schematic. Therefore, it should be noted that the relationship between thickness and planar dimensions, ratios, etc. are different from the actual ones, and there are parts where the dimensional relationships and ratios are different between the drawings.

[0014] FIG. 1 shows a front view of a schematic configuration of a flatness measuring device for flat steel according to an embodiment of the present invention. The flatness measuring device 1 for flat steel shown in FIG. 1 measures the flatness in the length direction (the direction in which the length l of the flat steel S extends) of the flat steel S placed on the upper surface 2a of the surface plate 2. Here, the flat steel S is manufactured by hot rolling, and the shape, dimensions, tolerances, appearance, and mass of the flat steel S are defined by JIS G 3194. Generally, as shown in FIG. 12, the flat steel S has a rectangular shape with a width w of 25 to 200 mm, a thickness t of 4.5 to 25 mm, and a length l of 7 m or less. The tolerance for the flatness in the length direction of this flat steel S is also defined by JIS G 3194. Here, the length direction of the flat steel S is, as shown in FIG. 12, the direction in which the length l of the flat steel S extends, the width direction of the flat steel S is the direction in which the width w of the flat steel S extends, and the thickness direction of the flat steel S is the direction in which the thickness t of the flat steel S extends. And the flatness in the length direction of the flat steel S means the uneven state of the upper surface Sa and the lower surface in the length direction of the flat steel S.

[0015] As shown in FIGS. 1 to 3, the surface plate 2 is a steel material formed in a rectangular shape extending in the width direction (the left - right direction in FIG. 2, the up - down direction in FIG. 3), the thickness direction (the up - down direction in FIG. 1, the up - down direction in FIG. 2), and the length direction (the left - right direction in FIG. 1, the left - right direction in FIG. 3). The upper surface 2a of the surface plate 2 on which the flat steel S is placed is a machined surface with unevenness eliminated by machining. As shown in FIGS. 1 and 2, the flat steel S is placed on the upper surface 2a of the surface plate 2 such that its length direction is parallel to the length direction of the surface plate 2 and the center of its width direction substantially coincides with the center of the width direction of the surface plate 2.

[0016] And the flatness measuring device 1 for flat steel shown in FIG. 1 includes a distance measuring device 10 and a flatness calculating device 40. The distance measuring device 10 has a measuring device body 11 that moves along the length of the flat steel S, and is equipped with a surface plate height distance meter 13 for measuring the distance A to the upper surface 2a of the surface plate 2 (see Figures 1 and 2) and a flat steel height distance meter 14 for measuring the distance B to the upper surface Sa of the flat steel S (see Figures 1 and 2).

[0017] The measuring device body 11 is composed of a traveling trolley that runs along the length direction of the flat steel S on the upper surface 2a of the surface plate 2, and comprises a rectangular trolley base 11a when viewed from above, and a box-shaped measuring section 11b provided on the trolley base 11a. Four wheels 12 that run on the upper surface 2a of the surface plate 2 are provided at the four corners of the trolley base 11a. The measuring device body 11 is designed to straddle the flat steel S on the upper surface 2a of the surface plate 2, and is capable of traveling in both directions along the length direction of the flat steel S, i.e., on the upper surface 2a of the surface plate 2 from one end of the surface plate 2 in the length direction (left end in Figure 1) to the other end in the length direction (right end in Figure 1), as indicated by arrow X, and on the upper surface 2a of the surface plate 2 from the other end in the length direction to the one end in the length direction, as indicated by arrow Y. An overrun prevention plate 32a of the measuring device body 11 is provided at one end of the surface plate 2 in the longitudinal direction, and an overrun prevention plate 32b of the measuring device body 11 is also provided at the other end of the surface plate 2 in the longitudinal direction.

[0018] As shown in Figures 1 to 3, the measuring device body 11 is connected to a drive motor 29, which acts as a drive unit for moving the measuring device body 11 in the longitudinal direction of the flat steel S. The measuring unit 11b of the measuring device body 11 is connected via a connector 31 to a drive chain 30 that is stretched between a first sprocket 27a provided on one end of the surface plate 2 in the longitudinal direction and a second sprocket 27b provided on the other end of the surface plate 2 in the longitudinal direction. The rotating shaft of the drive motor 29 is connected to the rotating shaft 28a of the first sprocket 27a. When the rotating shaft of the drive motor 29 rotates, the first sprocket 27a rotates, and as a result the drive chain 30 rotates together with the second sprocket 27b, causing the measuring device body 11 to travel in the longitudinal direction of the flat steel S via the connector 31. As shown in Figure 2, an L-shaped mounting plate 24 extending in the longitudinal direction of the surface plate 2 is attached to the rear surface of the surface plate 2 (right surface in Figure 2, top surface in Figure 3), and as shown in Figures 2 and 3, a U-shaped mounting plate 25 extending in the longitudinal direction of the surface plate 2 along the back surface of the surface plate 2 is attached to the top surface of the mounting plate 24. A mounting plate portion 26a that rotatably supports the rotation shaft 28a of the first sprocket 27a is attached to one end of the mounting plate 25 in the longitudinal direction, and a mounting plate portion 26b that rotatably supports the rotation shaft 28b of the second sprocket 27b is attached to the other end of the mounting plate 25 in the longitudinal direction.

[0019] Furthermore, as shown in Figures 1 to 3, an L-shaped mounting plate 21 extending in the longitudinal direction of the surface plate 2 is attached to the front surface of the surface plate 2 (the left surface in Figure 2, and the bottom surface in Figure 3). A first support plate 22a extending upward is attached to one end of the mounting plate 21 in the longitudinal direction, and a second support plate 22b extending upward is attached to the other end of the mounting plate 21 in the longitudinal direction. A first limit switch 23a is supported near the upper end of the first support plate 22a, and a second limit switch 23b is supported near the upper end of the second support plate 22b. A striker 15 capable of contacting both the first limit switch 23a and the second limit switch 23b is provided in the measuring section 11b of the measuring device body 11.

[0020] The drive motor 29 is connected to a control panel 50 that controls the operation of the drive motor 29, as shown in Figure 1. The control panel 50 is connected to an operation panel 60 and a first limit switch 23a and a second limit switch 23b. As shown in Figure 5, when the measuring device body 11 is at one end (left end) in the longitudinal direction of the surface plate 2, and the striker 15 is in contact with the first limit switch 23a, the operator turns on the drive switch on the control panel 60. The control panel 50 then drives the drive motor 29 to rotate the first sprocket 27a, the second sprocket 27b, and the drive chain 30, controlling the measuring device body 11 to move in the direction indicated by arrow X. When the measuring device body 11 moves in the direction of arrow X and the striker 15 on the measuring device body 11 makes contact with the second limit switch 23b, the control panel 50 stops the drive of the drive motor 29, controlling the measuring device body 11 to stop. After that, the operator turns off the drive switch on the control panel 60.

[0021] Furthermore, as shown in Figure 6, when the measuring device body 11 is at the other end (right end) in the longitudinal direction of the surface plate 2, and the striker 15 is in contact with the second limit switch 23b, the operator turns on the drive switch on the control panel 60. Then, the control panel 50 drives the drive motor 29 to rotate the first sprocket 27a, the second sprocket 27b, and the drive chain 30 in the opposite direction to the aforementioned direction, controlling the measuring device body 11 to move in the direction of arrow Y. When the measuring device body 11 moves in the direction indicated by arrow Y and the striker 15 provided on the measuring device body 11 makes contact with the first limit switch 23a, the control panel 50 stops the drive of the drive motor 29 and controls the measuring device body 11 to stop. After that, the operator turns off the drive switch on the control panel 60.

[0022] Furthermore, the platen height distance meter 13 provided on the measuring device body 11 is composed of a laser distance meter located near the rear end (right end in Figure 2, upper end in Figure 3) in the width direction of the measuring section 11b, as shown in Figures 2 and 3. A through hole 11c is formed in the trolley base 11a of the measuring device body 11 at a position vertically opposite to the platen height distance meter 13, as shown in Figures 2 and 3, to allow laser light from the platen height distance meter 13 to pass through. The platen height distance meter 13 measures the distance A (see Figures 1 and 2) from the platen height distance meter 13 to the upper surface 2a of the platen 2 as the measuring device body 11 moves along the length direction of the flat steel S.

[0023] Furthermore, the flat steel height distance meter 14 provided on the measuring device body 11 is composed of a laser distance meter provided near the center of the width direction of the measuring section 11b, as shown in Figures 2 and 3. A through hole 11d is formed in the trolley base 11a of the measuring device body 11 at a position opposite the flat steel height distance meter 14 in the vertical direction, as shown in Figures 2 and 3, so that the laser light from the flat steel height distance meter 14 can pass through. The flat steel height distance meter 14 measures the distance B (see Figures 1 and 2) from the flat steel height distance meter 14 to the upper surface Sa of the flat steel S as the measuring device body 11 moves along the length direction of the flat steel S.

[0024] When the measuring device body 11 moves from a state where the striker 15 is in contact with the first limit switch 23a to a state where it is in contact with the second limit switch 23b, the distance B from the flat steel height distance meter 14 to the upper surface Sa of the flat steel S is measured by the flat steel height distance meter 14 over the entire length of the flat steel S. The same applies when the measuring device body 11 moves in the opposite direction from a state where the striker 15 is in contact with the second limit switch 23b to a state where it is in contact with the first limit switch 23a. Furthermore, when the measuring device body 11 moves from a state where the striker 15 is in contact with the first limit switch 23a to a state where it is in contact with the second limit switch 23b, the measurement of the distance A from the surface plate height distance meter 13 to the upper surface 2a of the surface plate 2 by the surface plate height distance meter 13 is performed for a portion corresponding to the total length of the flat steel S. The same applies when the measuring device body 11 moves in the opposite direction from a state where the striker 15 is in contact with the second limit switch 23b to a state where it is in contact with the first limit switch 23a.

[0025] Here, when measuring the aforementioned distances A and B using the surface plate height distance meter 13 and the flat steel height distance meter 14, the measuring device body 11 travels at a speed of 300 m / sec, and the measurement cycle of the surface plate height distance meter 13 and the flat steel height distance meter 14 is 500 msec, with distances A and B measured at 200 mm intervals. The reason why the distance meter 13 for the surface plate height and the distance meter 14 for the flat steel height are set to measure the distance A to the upper surface 2a of the surface plate 2 and the distance B to the upper surface Sa of the flat steel S, respectively, at 200 mm intervals is to confirm the pitch characteristics of temperature strain that affect the flatness of the flat steel S in the longitudinal direction. The flatness of the flat steel S in the longitudinal direction is affected by the "strain" caused by the temperature difference in the longitudinal direction of the flat steel S in the equipment that cools the flat steel S (the cooling bed product annealing surface plate and the ribs placed on the cooling bed product annealing surface plate). Therefore, in this embodiment, considering the longitudinal direction of the ribs of the cooling bed product annealing surface plate, the aforementioned distances A and B are measured at 200 mm intervals so that the pitch characteristics of temperature strain caused by the cooling bed product annealing surface plate can be confirmed.

[0026] Furthermore, the flatness calculation device 40, which constitutes the flatness measuring device 1 for flat steel, includes a measurement data acquisition unit 41, a flatness calculation unit 42, and a display unit 43, as shown in Figure 1. The flatness calculation device 40 is a computer system with arithmetic processing functions, and executes the functions of the measurement data acquisition unit 41 (steps S1, S3, and S4, see Figure 4), the flatness calculation unit 42 (step S5), and the display unit 43 (step S6) according to the instructions of a computer program installed in a storage device (not shown).

[0027] The flatness calculation device 40 calculates the flatness of the flat steel S in the longitudinal direction using the distance A to the upper surface 2a of the surface plate 2, measured by the surface plate height distance meter 13 of the distance measuring device 10, and the distance B to the upper surface Sa of the flat steel S, measured by the flat steel height distance meter 14. An input device 44 is connected to the measurement data acquisition unit 41 of the flatness calculation device 40. When the operator measures the flatness of the flat steel S, they input a data acquisition start signal to the input device 44, and the measurement data acquisition unit 41 starts scanning based on the data acquisition start signal from the input device 44.

[0028] The measurement data acquisition unit 41 then collects the distance A from the surface plate height distance meter 13 to the upper surface 2a of the surface plate 2 and the distance B from the surface plate height distance meter 14 to the upper surface Sa of the surface plate S, which are measured as the distance measuring device 10 moves along the length of the flat steel S. Then, when the operator inputs a data collection stop signal to the input device 44, the measurement data collection unit 41 stops scanning based on the data collection stop signal from the input device 44. Furthermore, the flatness calculation unit 42 of the flatness calculation device 40 calculates the flatness in the longitudinal direction of the flat steel S using the distance A from the surface plate height distance meter 13 to the upper surface 2a of the surface plate 2, which is collected by the measurement data collection unit 41, and the distance B from the flat steel height distance meter 14 to the upper surface Sa of the flat steel S.

[0029] Here, the flatness calculation unit 42 calculates the flatness of the flat steel S in the longitudinal direction using the following equation (1). F = (AB) - (Maximum value along the length of B) ... (1) Here, F: flatness, A: distance to the top surface 2a of the surface plate 2, B: distance to the top surface Sa of the flat steel S Furthermore, the display unit 43 of the flatness calculation device 40 displays the calculation result from the flatness calculation unit 42, that is, the flatness of the flat steel S in the longitudinal direction, at measurement intervals of 200 mm.

[0030] Next, with reference to Figures 4 and 5, the method for measuring the flatness of flat steel using a flatness measuring device will be explained. Figure 4 is a flowchart illustrating the processing flow in the flatness measuring device for flat steel shown in Figure 1. Figure 5 is a diagram illustrating the method for measuring the flatness of flat steel using a flatness measuring device. First, the worker confirms that the striker 15 is in contact with the first limit switch 23a when the distance measuring device 10 is located at one end (left end) in the longitudinal direction of the surface plate 2, as shown in Figure 5. In this state, when the operator inputs a data acquisition start signal to the input device 44, the measurement data acquisition unit 41 of the flatness calculation device 40 starts scanning in step S1 (see Figure 4).

[0031] Next, the operator turns on the drive switch on the control panel 60. The control panel 50 then drives the drive motor 29 to rotate the first sprocket 27a, the second sprocket 27b, and the drive chain 30, controlling the measuring device body 11 to move in the direction indicated by arrow X. As a result, in step S2, the measuring device body 11 of the distance measuring device 10 moves in the longitudinal direction of the flat steel S, that is, on the upper surface 2a of the surface plate 2 from one end to the other in the direction indicated by arrow X, and the surface plate height distance meter 13 measures the distance A from the surface plate height distance meter 13 to the upper surface 2a of the surface plate 2 as the measuring device body 11 moves, and the flat steel height distance meter 14 measures the distance B from the flat steel height distance meter 14 to the upper surface Sa of the flat steel S.

[0032] Here, when measuring the aforementioned distances A and B using the surface plate height distance meter 13 and the flat steel height distance meter 14, the measuring device body 11 is 300 m The device travels at a speed of m / sec, and the measurement cycle of the surface plate height distance meter 13 and the flat steel height distance meter 14 is 500 msec, measuring distances A and B at 200 mm intervals. Then, when the striker 15 located on the measuring device body 11 makes contact with the second limit switch 23b, the control panel 50 stops the drive of the drive motor 29, thereby controlling the measuring device body 11 to stop. After that, the operator turns off the drive switch on the operation panel 60.

[0033] Next, in step S3, the measurement data acquisition unit 41 of the flatness calculation device 40 collects the distance A from the surface plate height distance meter 13 to the upper surface 2a of the surface plate 2 and the distance B from the surface plate height distance meter 14 to the upper surface Sa of the surface plate S, which are measured as the distance measuring device 10 moves along the length direction of the flat steel S. Next, when the operator inputs a data collection stop signal to the input device 44, the measurement data collection unit 41 of the flatness calculation device 40 stops scanning in step S4. Next, in step S5, the flatness calculation unit 42 of the flatness calculation device 40 calculates the flatness in the longitudinal direction of the flat steel S using the distance A from the surface plate height distance meter 13 to the upper surface 2a of the surface plate 2 and the distance B from the flat steel height distance meter 14 to the upper surface Sa of the flat steel S, which were collected in step S3, according to equation (1) above.

[0034] Finally, in step S6, the display unit 43 of the flatness calculation device 40 displays the calculation result from step S5, that is, the flatness of the flat steel S in the longitudinal direction, at measurement intervals of 200 mm. This completes the measurement of the flatness of the flat steel S by the flatness measuring device 1. Furthermore, it is preferable to perform zero-point adjustment in the distance measuring device 10 before measuring the flatness of the flat steel S using the flatness measuring device 1.

[0035] This zero-point adjustment is performed by moving the measuring device body 11 500 mm on the upper surface 2a of the surface plate 2 from one end to the other in the direction indicated by arrow X or from the other end to the first end in the direction indicated by arrow Y, with the flat steel S not placed on the upper surface 2a of the surface plate 2. The distance A from the surface plate height distance meter 13 to the upper surface 2a of the surface plate 2 is measured by the surface plate height distance meter 13, and the distance B from the flat steel height distance meter 14 to the upper surface Sa of the flat steel S (in this case, the upper surface 2a of the surface plate 2 since the flat steel S is not placed on it) is measured by the flat steel height distance meter 14. The absolute value of distance A - distance B is then calculated, and it is checked whether the absolute value is 0.05 mm or less. If the absolute value is not 0.05 mm or less, the position of the surface plate height distance meter 13 and the flat steel height distance meter 14 is adjusted so that the absolute value of distance A - distance B is 0.05 mm or less. Furthermore, it is preferable to perform zero-point adjustment as an automatic check condition for automatic startup.

[0036] Furthermore, it is preferable to perform calibration using gauge blocks once a month. Calibration using this gauge block involves placing the gauge block on the upper surface 2a of the surface plate 2, moving the distance measuring device 10 500 mm on the upper surface 2a of the surface plate 2 from one end to the other in the direction indicated by arrow X, or from the other end to the first end in the direction indicated by arrow Y, measuring the distance A from the surface plate height distance meter 13 to the upper surface 2a of the surface plate 2 using the surface plate height distance meter 13, and measuring the distance B from the flat steel height distance meter 14 to the upper surface of the gauge block using the flat steel height distance meter 14. The absolute value of distance A - distance B is calculated, and it is checked whether the absolute value is within the acceptable range. If the absolute value is not within the acceptable range, the position of the surface plate height distance meter 13 and the flat steel height distance meter 14 is adjusted so that the absolute value of distance A - distance B is within the acceptable range.

[0037] Furthermore, the measuring device body 11 of the distance measuring device 10 may not only move on the upper surface 2a of the surface plate 2 in the direction indicated by arrow X from one end to the other end of the surface plate 2 in step S2, but may also be moved on the upper surface 2a of the surface plate 2 in the direction indicated by arrow Y from the other end to the one end of the surface plate 2, as shown in Figure 6, so that the surface plate height distance meter 13 measures the distance A from the surface plate height distance meter 13 to the upper surface 2a of the surface plate 2 when the measuring device body 11 moves, and the flat steel height distance meter 14 measures the distance B from the flat steel height distance meter 14 to the upper surface Sa of the flat steel S.

[0038] As described above, the flatness measuring device 1 for flat steel according to this embodiment includes a distance measuring device 10, on which a surface plate height distance meter 13 for measuring the distance A to the upper surface 2a of the surface plate 2 and a flat steel height distance meter 14 for measuring the distance to the upper surface Sa of the flat steel S are attached to a measuring device body 11 that moves along the length direction of the flat steel S, and a flatness calculation device 40 that calculates the flatness in the length direction of the flat steel using the distance A to the upper surface 2a of the surface plate 2 measured by the surface plate height distance meter 13 and the distance B to the upper surface Sa of the flat steel S measured by the flat steel height distance meter 14.

[0039] Furthermore, according to the flatness measurement method for flat steel according to this embodiment, the measuring device body 11 of the distance measuring device 10, which is equipped with a surface plate height distance meter 13 for measuring the distance A to the upper surface 2a of the surface plate 2 and a flat steel height distance meter 14 for measuring the distance B to the upper surface Sa of the flat steel S, is moved along the length direction of the flat steel S, and the distance A to the upper surface 2a of the surface plate 2 is measured by the surface plate height distance meter 13, and the distance B to the upper surface Sa of the flat steel S is measured by the flat steel height distance meter 14 (step S2). Then, the flatness calculation device 40 calculates the flatness in the length direction of the flat steel S using the distance A to the upper surface 2a of the surface plate 2 measured by the surface plate height distance meter 13 and the distance B to the upper surface Sa of the flat steel S measured by the flat steel height distance meter 14 (steps S3, step S5).

[0040] This allows for safe and highly accurate measurement of the flatness of the flat steel S along its length. In other words, there is no need to manually measure the gap between the flat steel S and the upper surface 2a of the base plate 2 using a gap gauge, eliminating the risk of burns and making it safe. Furthermore, instead of visually finding the point where the gap between the flat steel S and the upper surface 2a of the base plate 2 is largest along its length and then measuring that gap with a gap gauge, the flatness along the entire length of the flat steel S is measured by the distance measuring device 10 and the flatness calculation device 40, resulting in high accuracy in measuring the flatness.

[0041] Furthermore, measuring the gap between the flat steel S and the upper surface 2a of the surface plate 2 using a manual "gap gauge" makes it difficult to measure a minimum gap of 0.3 mm or less. In contrast, according to the flatness measuring device 1 and flatness measuring method of the flat steel according to this embodiment, the measuring device body 11 of the distance measuring device 10 is moved along the length direction of the flat steel S, and the distance A to the upper surface 2a of the surface plate 2 is measured by the surface plate height distance meter 13, and the distance B to the upper surface Sa of the flat steel S is measured by the flat steel height distance meter 14 (step S2). Then, the flatness calculation device 40 calculates the flatness in the length direction of the flat steel S using the distance A to the upper surface 2a of the surface plate 2 measured by the surface plate height distance meter 13 and the distance B to the upper surface Sa of the flat steel S measured by the flat steel height distance meter 14 (steps S3, step S5). In measuring distances using a laser distance meter as a distance meter 13 for surface plate height and a distance meter 14 for flat steel height, the minimum resolution of the laser distance meter is 0.05 mm or less, making it easy to measure minimum gap measurements of 0.3 mm or less.

[0042] Furthermore, according to the flatness measuring device 1 and flatness measuring method for flat steel according to this embodiment, the flatness calculation device calculates the flatness in the longitudinal direction of the flat steel S using the above-mentioned equation (1). This allows for highly accurate calculation of the flatness of the flat steel S in the longitudinal direction. Furthermore, according to the flatness measuring device 1 of the flat steel according to this embodiment, the measuring device body 11 is composed of a traveling carriage that travels along the length direction of the flat steel S on the upper surface 2a of the surface plate 2. This allows the flatness measuring device 1 to be configured with a simple setup using a traveling carriage that moves along the length of the flat steel S on the upper surface 2a of the surface plate 2, enabling safe and highly accurate measurement of the flatness of the flat steel S in the length direction. Furthermore, according to the flatness measuring device 1 of this embodiment, the measuring device body 11 is connected to a drive unit that moves the measuring device body 11 along the length direction of the flat steel S. This allows the measuring device body 11, which is composed of a traveling carriage, to be automatically moved along the length of the flat steel S by the drive unit.

[0043] Next, an example in which the flatness measuring device for flat steel shown in Figure 1 is placed on the flat platen support of an automatic conveying device provided above the conveying surface of a conveying chain that conveys flat steel, and the flat steel S is placed from the conveying surface onto the flat platen by the automatic conveying device, and then placed from the flat platen onto the conveying surface, will be explained with reference to Figures 7 to 11. Figure 7 is a front view of an example in which the flatness measuring device for flat steel shown in Figure 1 is installed on the flatness support part of an automatic conveying device located above the conveying surface of the conveying chain that transports the flat steel. Figure 8 is a left side view of Figure 7. Figure 9 is a top view of Figure 7. In the following description of the automated transport system, the terms indicating directions such as "up," "down," "left," "right," "front," and "back" are defined based on the directions indicated by the arrows in Figures 7 to 11.

[0044] The automatic conveying device 100 shown in Figures 7 to 9 conveys flat steel S, which is transported in the backward direction indicated by arrow a in Figure 8 by the conveying chain 140, onto the upper surface 2a of the surface plate 2 installed on the surface plate support 101a, and places the flat steel S, whose flatness has been calculated by the flatness measuring device 1, onto the conveying surface 141 of the conveying chain 140. As shown in Figures 7 to 9, the automatic transport device 100 is installed above the transport surface 141 of the transport chain 140 and is equipped with four support columns 101 erected at predetermined intervals in the left-right direction perpendicular to the transport direction of the transport chain 140 (the rear direction indicated by arrow a and the forward direction indicated by arrow b in Figure 8). As shown in Figures 8 and 9, each support column 101 is supported on the front side of a work platform 102 supported on the ground.

[0045] Furthermore, a surface plate support portion 101a is provided at the lower end of each support column 101. The surface plate 2 is installed on the upper surface of each surface plate support portion 101a such that its length is in the left-right direction. Furthermore, of the four support columns 101, two adjacent support columns 101 located in the center in the left-right direction have a movable body support member 103 attached to their vertical intermediate portion, extending forward from each support column 101. A first support member 104 extending upward from each movable body support member 103 is attached to the rear end of each movable body support member 103, and a second support member 105 extending upward from each movable body support member 103 is attached to the front end of each movable body support member 103. The upper ends of the first support member 104 and the upper ends of the second support member 105 are connected by a third support member 106. In addition, the vertical intermediate portions of two adjacent first support members 104 located in the left-right direction are connected by a cylinder support member 107.

[0046] Here, the automatic transport device 100 includes a movable body 108 that moves in the front-rear direction. As shown in Figures 7 to 9, the movable body 108 is composed of a rectangular member extending in the front-rear, left-right, and up-down directions, and is movable in the front-rear direction by a movable body drive cylinder 111 attached to a cylinder support member 107. Two rotating shafts 109 extending in the left-right direction are provided on the movable body 108 at a predetermined distance apart, passing through the movable body 108. Pinion gears 110 are provided at both ends of each rotating shaft 109 in the left-right direction, and each pinion gear 110 moves in the front-rear direction on a rack (not shown) provided on the movable body support member 103. The movable body drive cylinder 111 is attached to the cylinder support member 107, and the cylinder rod 112 of the movable body drive cylinder 111 is attached to the movable body 108 by a connecting member 113.

[0047] Furthermore, the automatic transport device 100 is equipped with a permanent magnet assembly lifting member 121 that moves vertically. The permanent magnet assembly lifting member 121 is a member that extends elongated horizontally, and multiple permanent magnet assemblies 130 (9 in this example) are attached to it at a predetermined pitch in the horizontal direction. The permanent magnet assembly lifting member 121 is attached to two vertically extending screw shafts 115 that move up and down by two ball jacks 114 attached to the mobile body 108. An input shaft 117, which acts as a worm shaft and rotates via a gearbox 116 driven by a motor 118, enters each ball jack 114, and a screw shaft 115, which acts as a worm wheel, meshes with this input shaft 117, causing the screw shaft 115 to move up and down as the input shaft 117 rotates. The permanent magnet assembly lifting member 121 moves up and down as the motor 118 drives each screw shaft 115 up and down. The permanent magnet assembly lifting member 121 is fitted with two guide shafts 120 that extend in the vertical direction, and each guide shaft 120 is inserted into the movable body 108 via a linear bush 119. Each guide shaft 120 guides the lifting and lowering of the permanent magnet assembly lifting member 121 when the permanent magnet assembly lifting member 121 moves up and down.

[0048] Figure 10 shows a permanent magnet assembly provided in the automatic transport device shown in Figure 7, and shows the state before the permanent magnets on the permanent magnet assembly attract the flat steel (after release). Figure 11 also shows a permanent magnet assembly provided in the automatic transport device shown in Figure 7, and shows the state after the permanent magnets on the permanent magnet assembly attract the flat steel (before release).

[0049] As shown in Figures 10 and 11, the permanent magnet assembly 130 includes a hollow box 137 attached to the upper surface of the permanent magnet assembly lifting member 121, an air cylinder 131 attached to the upper surface of the box 137, and a permanent magnet holder 136 attached to the lower surface of the permanent magnet assembly lifting member 121. A hollow first shaft 133 is attached to the cylinder rod 132 of the air cylinder 131. A second shaft 134 is attached to the first shaft 133. The flange portion 134a at the upper end of the second shaft 134 is located in the space 133a of the first shaft 133, allowing it to move up and down relative to the first shaft 133. At the lower end of the second shaft 134, a plurality of permanent magnets 135 for attracting flat steel S are attached inside the permanent magnet holder 136. A spring member 138 is wound around the second shaft 134 to bias it upward.

[0050] As shown in Figure 10, when the air cylinder 131 is operated (attraction operation) before the permanent magnet 135 attracts the flat steel S (after release), the cylinder rod 132 descends together with the first shaft 133, and the second shaft 134, which has a flange portion 134a within the air-filled space 133a of the first shaft 133, also descends together with the first shaft 133 against the biasing force of the spring member 138, as shown in Figure 11, and the permanent magnet 135 attached to the lower end of the second shaft 134 attracts the upper surface Sa of the flat steel S.

[0051] On the other hand, as shown in Figure 11, when the operation of the air cylinder 131 is stopped (release operation) after the permanent magnet 135 has attracted the flat steel S (before releasing it), the cylinder rod 132 rises together with the first shaft 133, and the second shaft 134 also rises initially due to the biasing force of the spring member 138 and then lifted up by the first shaft 133, causing the permanent magnet 135 to rise as well. At this time, as shown in Figure 11, the flat steel S attracted to the permanent magnet 135 comes into contact with the permanent magnet holder 136, causing the permanent magnet 135 to separate from the upper surface Sa of the flat steel S, releasing the attraction of the flat steel S by the permanent magnet 135, and the flat steel S is released.

[0052] Next, we will explain a method for placing the flat steel S, which is being transported by the automatic transport device 100 via the transport chain 140 in the direction indicated by arrow a in Figure 8, onto the upper surface 2a of the surface plate 2 installed on the surface plate support section 101a. First, as shown in Figure 8, when the flat steel S is transported by the transport chain 140 in the direction indicated by arrow a in Figure 8, the operator presses the rise button of the product stopper (not shown) on the machine-side control panel (not shown) (not shown) to raise the product stopper. Next, when the flat steel S reaches the product stopper, the center line CLS in the width direction of the flat steel S becomes the stopping position X in the front-to-back direction, so the operator presses the stop button for the conveyor chain 140 on the machine's control panel to stop the conveyor chain 140.

[0053] Next, after the transport chain 140 stops, the operator operates a push button on a pendant switch (not shown) to activate the mobile body drive cylinder 111, moving the mobile body 108 forward as indicated by arrow b in Figure 8, until the center CL121 of the permanent magnet assembly lifting member 121 is in approximately the same position as the center CLS in the width direction of the flat steel S on the transport surface 141 of the transport chain 140. Next, the operator operates a push button on the pendant switch to drive the motor 118, which lowers each screw shaft 115 and lowers the permanent magnet assembly lifting member 121 in the downward direction indicated by arrow c in Figure 8. At this time, the permanent magnet assembly lifting member 121 is lowered to a position where the permanent magnet holder 136 of the permanent magnet assembly 130 attached to the permanent magnet assembly lifting member 121 is gaped from the upper surface Sa of the flat steel S, as shown in Figure 11.

[0054] Next, the worker operates a push button on the pendant switch to activate (attach) the air cylinder 131 of the permanent magnet assembly 130, causing the permanent magnet 135 to attract the upper surface Sa of the flat steel S. Next, the worker operates a push button on the pendant switch to drive the motor 118, raising each screw shaft 115, and raising the permanent magnet assembly lifting member 121, to which the permanent magnet assembly 130 is attracted, upward in the direction indicated by arrow d in Figure 8. Next, the operator operates the push button on the pendant switch to activate the movable body drive cylinder 111, moving the movable body 108 in the rearward direction indicated by arrow a in Figure 8, until the center CL121 of the permanent magnet assembly lifting member 121 is in approximately the same position as the center in the width direction of the base plate 2.

[0055] Next, the operator operates a push button on the pendant switch to drive the motor 118, which lowers each screw shaft 115, causing the permanent magnet assembly lifting member 121, to which the flat steel S is attracted by the permanent magnet assembly 130, to descend in the direction indicated by arrow c in Figure 8. At this time, the permanent magnet assembly lifting member 121 is lowered until the flat steel S, attracted by the permanent magnet 135, is placed on the upper surface 2a of the surface plate 2. Next, the push button on the pendant switch is operated to stop the operation (release operation) of the air cylinder 131 of the permanent magnet assembly 130, releasing the flat steel S from the permanent magnet 135 and releasing the flat steel S.

[0056] As a result, the flat steel S is placed on the upper surface 2a of the surface plate 2, which is installed on the surface plate support part 101a, with the center of the flat steel S in the width direction approximately coinciding with the center of the surface plate 2 in the width direction. After the flat steel S is placed on the upper surface 2a of the surface plate 2, the worker operates a push button on the pendant switch to drive the motor 118 to raise each screw shaft 115, raise the permanent magnet assembly lifting member 121, and return the permanent magnet assembly lifting member 121 to its original position. Subsequently, the flatness of the flat steel S is measured using the flatness measurement method for flat steel described above.

[0057] Once the measurement of the flatness of the flat steel S is complete, the operator operates a push button on the pendant switch to drive the motor 118, which lowers each screw shaft 115 and lowers the permanent magnet assembly lifting member 121. At this time, the permanent magnet assembly lifting member 121 is lowered until the permanent magnet holder 136 of the permanent magnet assembly 130 attached to the permanent magnet assembly lifting member 121 contacts the upper surface Sa of the flat steel S, as shown in Figure 10. Next, the worker operates a push button on the pendant switch to activate (attach) the air cylinder 131 of the permanent magnet assembly 130, causing the permanent magnet 135 to attract the upper surface Sa of the flat steel S.

[0058] Next, the worker operates a push button on the pendant switch to drive the motor 118, which raises each screw shaft 115, thereby raising the permanent magnet assembly lifting member 121, to which the permanent magnet assembly 130 is attracted to the flat steel S. Next, the operator operates a push button on the pendant switch to activate the mobile body drive cylinder 111, moving the mobile body 108 forward until the center CL121 of the permanent magnet assembly lifting member 121 is in the position where the flat steel S is placed on the conveying surface 141 of the conveying chain 140.

[0059] Next, the operator operates a push button on the pendant switch to drive the motor 118, which lowers each screw shaft 115 and lowers the permanent magnet assembly lifting member 121. At this time, the permanent magnet assembly lifting member 121 is lowered until the flat steel S attracted to the permanent magnet 135 is placed on the conveying surface 141 of the conveying chain 140. Next, the push button on the pendant switch is operated to stop the operation (release operation) of the air cylinder 131 of the permanent magnet assembly 130, releasing the flat steel S from the permanent magnet 135 and releasing the flat steel S.

[0060] Subsequently, the operator presses the travel button for the transport chain 140 on the machine's control panel, causing the transport chain 140 to move forward as indicated by arrow b in Figure 8. This completes the series of operations: placing the flat steel S, which is being transported by the transport chain 140 in the backward direction indicated by arrow a in Figure 8, onto the upper surface 2a of the surface plate 2 installed on the surface plate support 101a, and then placing the flat steel S, whose flatness has been calculated by the flatness measuring device 10, onto the transport surface 141 of the transport chain 140.

[0061] In this series of operations using the automated conveying device 100, it is not necessary to manually place the flat steel S, which is being conveyed in the backward direction indicated by arrow a by the conveying chain 140, onto the upper surface 2a of the surface plate 2 installed on the surface plate support 101a, nor is it necessary to manually place the flat steel S from the upper surface 2a of the surface plate 2 onto the conveying surface 141 of the conveying chain 140. Therefore, there is no risk of hands or other body parts coming into contact with the hot flat steel, and the series of operations, including the measurement of the flatness of the flat steel S, can be performed safely and efficiently.

[0062] Although embodiments of the present invention have been described above, the present invention is not limited thereto and can be modified and improved in various ways. For example, the measuring device body 11 does not necessarily have to be a traveling trolley that moves along the length of the flat steel S on the upper surface 2a of the surface plate 2, as long as it moves along the length of the flat steel S. For example, the measuring device body 11 may be an overhead crane that moves along the length of the flat steel S. Furthermore, although the surface plate height distance meter 13 is installed near the rear end (right end in Figure 2) in the width direction of the measuring unit 11b, the installation location is not limited to that position as long as it is a position in which the distance A to the upper surface 2a of the surface plate 2 can be measured. Also, the number of surface plate height distance meters 13 is not limited to one, but may be multiple.

[0063] Furthermore, although the distance meter 14 for measuring the height of the flat steel is installed near the center of the widthwise direction of the measuring section 11b, the installation location is not limited to that position as long as it is a location where the distance B to the upper surface Sa of the flat steel S can be measured. Also, the number of distance meters 14 for measuring the height of the flat steel is not limited to one, but may be multiple. Furthermore, although the flatness measuring device 1 was described in an example where its surface plate 2 was placed on the surface plate support portion 101a of an automatic conveying device 100, which is located above the conveying surface 141 of the conveying chain 140 that conveys the flat steel S, as shown in Figures 7 to 9, the application of the flatness measuring device 1 is not limited to this case. [Examples]

[0064] The flatness of a flat steel S with a thickness t of 12 mm, a width w of 200 mm, a length l of 6.0 m, a unit weight of 112.8 kg, and a product temperature of 240°C was measured using the flatness measuring device 1 shown in Figure 1. As shown in Figures 7 to 9, the flatness measuring device 1 was used by placing its surface plate 2 on the surface plate support part 101a of an automatic conveying device 100, which is located above the conveying surface 141 of the conveying chain 140 that conveys the flat steel S, and performing the measurement. As a result, the flatness of the flat steel S at 200 mm intervals along its length (including cases where the flatness is 0.3 mm or less) could be measured safely and accurately over the entire length of the flat steel S.

[0065] Furthermore, the guidance of the flat steel S from the conveying surface 141 of the conveying chain 140 by the automatic conveying device 100 to the upper surface 2a of the surface plate 2, and the guidance of the flat steel S from the upper surface 2a of the surface plate 2 to the conveying surface 141 of the conveying chain 140, could be performed safely and quickly. [Explanation of symbols]

[0066] 1. Flatness measuring device 2 Surface plate 2a Top side 10 Distance measuring device 11 Measuring device main body 11a Bogie base 11b Measuring part 11c through hole 11d through hole 12 wheels 13. Distance meter for surface plate height 14. Distance meter for measuring the height of flat steel. 15 Striker 21 Mounting plate 22a 1st support plate 22b 2nd support plate 23a First limit switch 23b Second limit switch 24 Mounting plate 25 Mounting plate 26a Mounting plate section 26b Mounting plate section 27a First sprocket 27b Second sprocket 28a Rotation axis 28b Rotation axis 29 Drive motor 30 drive chain 31 Connection part 32a Overrun prevention plate 32b Overrun prevention plate 40 Flatness Calculation Device 41 Measurement Data Acquisition Unit 42 Flatness Calculation Unit 43 Display section 44 Input devices 50 Control Panel 60 Control panel 100 Automatic transport devices 101 Post 101a Surface plate support 102 Scaffolding 103 Movable body support member 104 First support member 105 Second support member 106 Third support member 107 Cylinder support member 108 Mobile Units 109 Rotation axis 110 Pinion Gear 111 Mobile drive cylinder 112 Cylinder rod 113 Connecting member 114 Ball Jack 115 Screw shaft 116 Gearbox 117 input axes 118 Motor 119 Linear bushing 120 Guide Axis 121 Permanent magnet assembly lifting member 130 Permanent Magnet Assembly 131 Air Cylinder 132 Cylinder rod 133 1st axis 134 2nd axis 134a Flange section 135 Permanent Magnets 136 Permanent Magnet Holder 137 Box body 138 Spring component 140 Conveyor Chain 141 Conveying surface S flat steel Sa top surface

Claims

1. A flatness measuring device for measuring the flatness of a flat steel piece placed on the upper surface of a surface plate in the longitudinal direction, The measuring device body moves along the length of the flat steel and is equipped with a distance measuring device for measuring the distance to the top surface of the surface plate and a distance measuring device for measuring the distance to the top surface of the flat steel. The flatness calculation device calculates the flatness of the flat steel in the length direction using the distance to the top surface of the surface plate measured by the distance to the top surface of the surface plate and the distance to the top surface of the flat steel measured by the distance measuring device. The aforementioned distance meter for measuring the height of the flat steel measures the distance to the top surface of the flat steel at measurement intervals along the entire length of the flat steel, The aforementioned surface plate height distance meter measures the distance to the top surface of the surface plate at measurement intervals along the entire length of the flat steel, simultaneously with the measurement of the height to the top surface of the flat steel by the flat steel height distance meter. The flatness calculation device calculates the flatness for each measurement pitch along the entire length of the flat steel using the distance to the top surface of the flat steel measured at each measurement pitch along the entire length of the flat steel using the distance meter for the height of the flat steel and the distance to the top surface of the flat steel measured at each measurement pitch along the entire length of the flat steel using the distance meter for the height of the flat steel, The flatness calculation device is a flatness measuring device for flat steel, characterized in that it calculates the flatness for each measurement pitch along the entire length of the flat steel using the following formula (1). F = (A - B) - (A - the maximum value among multiple values ​​of B along the length direction) ... (1) Here, F: flatness, A: distance to the top surface of the surface plate, B: distance to the top surface of the flat steel.

2. The flatness measuring device for flat steel according to claim 1, characterized in that the measuring device body is composed of a traveling trolley that travels along the length direction of the flat steel on the upper surface of the surface plate.

3. The flatness measuring device for flat steel according to claim 2, characterized in that the measuring device body is connected to a drive unit that moves the measuring device body along the length direction of the flat steel.

4. The flatness measuring device for flat steel according to claim 1, characterized in that the distance meter for the height of the surface plate and the distance meter for the height of the flat steel measure the distance to the top surface of the surface plate and the distance to the top surface of the flat steel, respectively, at 200 mm intervals.

5. The flatness measuring device for flat steel according to claim 1, characterized in that the flat steel is a plate material manufactured by hot rolling having a rectangular shape with a width of 25 to 200 mm, a thickness of 4.5 mm to 25 mm, and a length of 7 m or less.

6. A method for measuring the flatness of a flat steel bar placed on the upper surface of a surface plate, wherein the flatness of the flat steel bar in the longitudinal direction is measured, A distance measuring device is provided, in which a base plate height distance meter for measuring the distance to the top surface of the base plate and a flat steel height distance meter for measuring the distance to the top surface of the flat steel are attached to the measuring device body which moves along the length of the flat steel, and the distance to the top surface of the base plate is measured by the base plate height distance meter at measurement pitches along the entire length of the flat steel, simultaneously with the measurement of the height to the top surface of the flat steel by the flat steel height distance meter, and the distance to the top surface of the flat steel is measured by the flat steel height distance meter at measurement pitches along the entire length of the flat steel, The flatness calculation device calculates the flatness for each measurement pitch along the entire length of the flat steel using the distance to the top surface of the flat steel measured at each measurement pitch along the entire length of the flat steel using the distance meter for the height of the flat steel, and the distance to the top surface of the flat steel measured at each measurement pitch along the entire length of the flat steel using the distance meter for the height of the flat steel, The flatness calculation device is characterized by calculating the flatness for each measurement pitch along the entire length of the flat steel using the following equation (1). F = (A - B) - (A - the maximum value among multiple values ​​of B along the length direction) ... (1) Here, F: flatness, A: distance to the top surface of the surface plate, B: distance to the top surface of the flat steel.

7. The method for measuring the flatness of a flat steel according to claim 6, characterized in that the distance meter for the height of the surface plate and the distance meter for the height of the flat steel measure the distance to the top surface of the surface plate and the distance to the top surface of the flat steel, respectively, at 200 mm intervals.

8. The method for measuring the flatness of a flat steel according to claim 6, characterized in that the flat steel is a plate material manufactured by hot rolling having a rectangular shape with a width of 25 to 200 mm, a thickness of 4.5 mm to 25 mm, and a length of 7 m or less.

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