Method for measuring the shape of a cast slab, method for inspecting surface quality, and shape measuring apparatus.
The method and device use laser-based measurement to assess the shape and quality of slab corners, addressing the limitations of existing technologies by accurately detecting defects and enhancing process reliability.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- JFE STEEL CORP
- Filing Date
- 2024-11-25
- Publication Date
- 2026-06-04
AI Technical Summary
Existing methods for measuring the shape of slabs, such as camera photography and optical cutting, fail to accurately measure the corner portions, which can lead to undetected surface defects like seam defects in subsequent hot rolling processes.
A method and device using a planar laser beam to irradiate and detect reflected light from the short and long sides of the corner portion, calculating the phase change and distance to determine the shape and surface quality of the corner, including three-dimensional profiling.
Accurately measures the shape and surface quality of the corner portions, predicting and preventing seam defects by identifying irregularities and abnormalities, reducing maintenance costs and improving process efficiency.
Smart Images
Figure 2026091650000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for measuring the shape of a slab, a method for inspecting surface quality, and a shape measuring device.
Background Art
[0002] Regarding slabs such as slabs manufactured in the steel process, in order to inspect quality defects such as bulging and surface cracks, measurement of the surface shape is performed. For example, Patent Documents 1 and 2 disclose that when measuring the surface shape of the long side surface, which is one surface of the slab, methods such as camera photography, the optical cutting method, the light wave phase difference detection method, and the moire fringe measurement method are used as the measurement methods.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Patent Document 2
Summary of the Invention
Problems to be Solved by the Invention
[0004] In slabs such as slabs, since it causes surface defects in the rolled product, the shape of the corner portion is also important. For example, when the shape of the corner portion is concave, this shape may cause a seam defect in the subsequent hot rolling process. However, since the methods of Patent Documents 1 and 2 are methods for measuring only the shape of one surface of the long side surface, the corner portion cannot be measured, and it has been difficult to detect such surface defects in advance.
[0005] Therefore, the present invention has been made paying attention to the above problems, and an object thereof is to provide a method for measuring the shape of a slab, a method for inspecting surface quality, and a shape measuring device capable of measuring the shape of the corner portion of the slab.
Means for Solving the Problems
[0006] (1) According to one aspect of the present invention, a method for measuring the shape of a corner portion of a cast slab having a rectangular cross-sectional shape in a cross-section perpendicular to the longitudinal direction is provided, comprising: an irradiation step of irradiating a planar laser beam at a plurality of irradiation positions on the short side surface and the long side surface of the corner portion; a light receiving step of detecting reflected light from the laser beam; and a shape calculation step of calculating the shape of the two surfaces of the short side surface and the long side surface at the corner portion by calculating the phase change of the reflected light and calculating the distance to the plurality of irradiation positions.
[0007] (2) In the method for measuring the shape of the cast slab described in (1) above, the shape calculation step is to calculate the angle of the corner portion in the cross-section as the shape of the two surfaces.
[0008] (3) In the method for measuring the shape of the cast slab described in (2) above, in the shape calculation step, the angle is calculated from the approximate straight line of the short side and the approximate straight line of the long side at the corner of the cross section.
[0009] (4) In the method for measuring the shape of the cast slab described in (1) above, in the irradiation step, the laser beam is continuously irradiated onto multiple longitudinal positions of the cast slab; in the light receiving step, the reflected light of the continuously irradiated laser beam is continuously detected; and in the shape calculation step, the profile of the three-dimensional shape of the corner portion is determined as the shape of the two surfaces from the distances to the multiple irradiation positions at the multiple longitudinal positions.
[0010] (5) According to one aspect of the present invention, a surface quality inspection method for a cast slab having a rectangular cross-sectional shape in a cross-section perpendicular to the longitudinal direction is provided, comprising: an irradiation step of irradiating a planar laser beam at a plurality of irradiation positions on the short side and long side of the corner; a light receiving step of detecting reflected light from the laser beam; a shape calculation step of calculating the shape of the two surfaces of the corner, the short side and the long side, by calculating the phase change of the reflected light and the distance to the plurality of irradiation positions; and a quality inspection step of evaluating the surface quality of the corner from the shapes of the two surfaces.
[0011] (6) In the surface quality inspection method of the cast slab described in (5) above, in the shape calculation step, the angle of the corner portion in the cross section is calculated as the shape of the two surfaces, and in the quality inspection step, it is determined that there is an abnormality in the surface quality if the angle is less than or equal to a first threshold of less than 90 degrees, and if the angle is greater than or equal to a second threshold of more than 90 degrees.
[0012] (7) In the surface quality inspection method of the cast slab described in (5) above, in the irradiation step, the laser beam is continuously irradiated onto a plurality of longitudinal positions of the cast slab; in the light receiving step, the reflected light of the continuously irradiated laser beam is continuously detected; in the shape calculation step, the profile of the three-dimensional shape of the corner portion is determined as the shape of the two surfaces from the distances to the plurality of irradiation positions at the plurality of longitudinal positions; and from the three-dimensional shape profile, if there is an irregularity in the longitudinal direction of at least one of the long side surface and the short side surface that exceeds a predetermined value, it is determined that there is an abnormality in the surface quality.
[0013] (8) According to one aspect of the present invention, a shape measuring device for a cast slab having a rectangular cross-sectional shape in a cross section perpendicular to the longitudinal direction is provided, comprising: an irradiator that irradiates a planar laser beam at a plurality of irradiation positions on the short side surface and the long side surface of the corner; a light receiver that detects reflected light of the laser beam; and a calculation device that calculates the shape of the two surfaces, the short side surface and the long side surface, at the corner by calculating the phase change of the reflected light and the distance to the cast slab. [Effects of the Invention]
[0014] According to one aspect of the present invention, a method for measuring the shape of a cast slab, a method for inspecting surface quality, and a shape measuring apparatus are provided that can measure the shape of the corner portion of the cast slab. [Brief explanation of the drawing]
[0015] [Figure 1] This is an explanatory diagram showing a shape measuring device for a cast slab according to an embodiment of the present invention. [Figure 2] This is a schematic diagram showing the cross-sectional shape of a cast slab. [Figure 3] This is an explanatory diagram showing the state when laser light is shone on the corner. [Figure 4] This graph shows the measurement results of the corner distance. [Modes for carrying out the invention]
[0016] The following detailed description will illustrate embodiments of the present invention with reference to the drawings. In the drawings, identical or similar parts are denoted by the same or similar reference numerals, and redundant descriptions are omitted. Each drawing is schematic and may differ from reality. Furthermore, the embodiments shown below are illustrative of apparatus and methods for realizing the technical idea of the present invention, and the technical idea of the present invention is not limited to the materials, structure, arrangement, etc., of the components described below. The technical idea of the present invention can be modified in various ways within the technical scope defined by the claims described in the patent claims.
[0017] <First Embodiment> (Slab Shape Measuring Device) Referring to FIG. 1, a slab shape measuring device according to a first embodiment of the present invention will be described. As shown in FIG. 1, the shape measuring device 1 measures the shape of the corner portion 21 of the slab 2 and inspects the surface quality of the corner portion 21 based on the measurement result.
[0018] The slab 2 is a slab or bloom continuously cast by a continuous casting facility, and as shown in FIGS. 1 and 2, has a rectangular cross-sectional shape in a cross-section (orthogonal cross-section) orthogonal to the longitudinal direction (the left-right direction in FIG. 1 and the front-back direction in FIG. 2). That is, the slab 2 is composed of a pair of short sides 22 and a pair of long sides 23 and has four corner portions 21. Further, the outer surface, which is the surface of the slab 2 excluding both end surfaces (front end surface and rear end surface) in the longitudinal direction, is composed of a pair of short side surfaces that become the short sides 22 in the orthogonal cross-section and a pair of long side surfaces that become the long sides 23 in the orthogonal cross-section. In the present embodiment, the slab 2 is a slab continuously cast by a vertical bending type continuous casting machine. In a continuous casting machine such as a vertical bending type continuous casting machine, molten steel is cast into a slab that is continuous in the casting direction within the continuous casting machine with a predetermined cross-sectional shape corresponding to the mold, and is cut by a cutting device to form a slab 2 of a predetermined length. The cut slab 2 is conveyed to the next process by a conveying facility composed of conveying rollers 3 and the like.
[0019] The shape measuring device 1 includes an irradiator 11, a light receiver 12, an arithmetic device 13, and a cooling box 14. The shape measuring device 1 measures the shape of the corner portion 21 of the slab 2 conveyed by the conveying facility. Also, in the example shown in FIG. 1, the shape of one corner portion 21 on the upper side in the vertical direction and on the right side as viewed from the conveying direction among the four corner portions 21 of the slab 2 is measured. In the following description, the symbol of the corner portion whose shape is measured is 21a, and the symbols of the short side and long side constituting the corner portion 21a are also described as 22a and 23a.
[0020] The irradiator 11 irradiates a laser beam onto the corner portion 21a of the slab 2 to be measured. As shown in FIG. 3, the irradiator 11 irradiates a planar laser beam onto both the short side surface and the long side surface of the corner portion 21a to be measured. The laser beam (irradiation light) irradiated from the irradiator 11 is a laser beam that spreads in a fan shape and is irradiated to a plurality of irradiation positions on the short side 22a and the long side 23a in a direction perpendicular to the longitudinal direction of the slab 2, as indicated by the white circles in FIG. 3. Further, the laser beam irradiated from the irradiator 11 is preferably a blue laser beam. The irradiator 11 is provided outside the corner portion 21a to be measured as viewed from the conveyance direction, at positions spaced a predetermined distance from the short side surface and the long side surface, respectively.
[0021] The light receiver 12 detects the reflected light of the laser beam irradiated from the irradiator 11 onto the corner portion 21a and measures the phase of the reflected light. The light receiver 12 is provided at a position spaced a predetermined distance in the conveyance direction from the irradiator 11 so as to be able to detect the reflected light of the irradiation light from the slab 2. Further, the light receiver 12 may be provided at the same position as the irradiator 11 as viewed from the conveyance direction. The detection result of the reflected light by the light receiver 12 is transmitted to the arithmetic unit 13. Further, the irradiator 11 and the light receiver 12 are installed within a range where the slab 2 can be measured. For example, when the measurable range of the irradiator 11 and the light receiver 12 is 495 mm or more and 1555 mm or less, the distance between the corner portion 21a and the irradiator 11 and the light receiver 12 is preferably 500 mm or more.
[0022] The calculation unit 13 calculates the shape of the two surfaces of the corner portion 21a, the short side and the long side, by measuring the phase change of the reflected light based on the detection result of the reflected light by the light receiver 12 and calculating the distance to the cast slab 2. The calculation unit 13 also inspects the surface quality of the corner portion 21a based on the calculated shape of the two surfaces of the corner portion 21a. The calculation unit 13 has an acquisition unit 131, a distance calculation unit 132, a shape calculation unit 133, and an evaluation unit 134. The acquisition unit 131 acquires the phase of the irradiated laser beam and the phase of the reflected light from the irradiator 11 and the light receiver 12, respectively. The distance calculation unit 132 calculates the phase change of the reflected light (phase difference with the irradiated light) from the acquired phase of the irradiated laser beam and the phase of the reflected light and calculates the distance from the light receiver 12 to the corner portion 21a of the cast slab 2. The shape calculation unit 133 calculates the shape of the corner portion 21a based on the distance calculated by the distance calculation unit 132. The evaluation unit 134 evaluates the surface quality of the corner portion 21 of the cast slab 2 based on the shape of the corner portion 21a calculated by the shape calculation unit 133. Details of each function of the calculation device 13 will be described later. The calculation device 13 is, for example, a computer system such as a personal computer with calculation processing capabilities, and is configured to include ROM, RAM, CPU, etc. The calculation device 13 implements the functions of the acquisition unit 131, distance calculation unit 132, shape calculation unit 133, and evaluation unit 134 in software by executing various dedicated programs pre-stored in ROM, etc. The calculation device 13 may also be provided with a storage device for storing measurement results from the light receiver 12 and calculation results such as distance and shape.
[0023] The cooling box 14 is a box whose interior is cooled by air, and it houses the irradiator 11 and the light receiver 12. The surface of the cooling box 14 that is struck by the laser beam from the irradiator 11 and the surface that is struck by the reflected light from the light receiver 12, i.e., the lower surface in Figure 1, is made of a transparent material. This configuration allows for the irradiation of the cast slab 2 with a laser beam by the irradiator 11 and the detection of the reflected light by the light receiver 12.
[0024] (Method for measuring the shape of a cast slab) Next, a method for measuring the shape of the cast slab 2 according to the first embodiment will be described. In the method for measuring the shape of the cast slab 2 according to the first embodiment, first, the irradiator 11 irradiates the corner portion 21a of the cast slab 2, which is being transported by the transport roller 3, with a laser beam (irradiation step). The cast slab 2 is transported at a speed of, for example, about 60 m / min. In the irradiation step, as shown in Figures 1 and 3, a planar laser beam is irradiated from one irradiator 11 to both the short side and the long side of the corner portion 21a at a predetermined longitudinal position. That is, as shown in Figure 3, the laser beam is irradiated to multiple irradiation positions on the short side 22a and the long side 23a of the corner portion 21a at a predetermined longitudinal position. The area (length in a cross-sectional orthogonal section) and the number of irradiation positions on the short side and long side of the corner portion 21a that are irradiated with the laser beam are set appropriately according to the required measurement accuracy. Considering the effectiveness of the approximate straight line described later, it is preferable to measure a length of 100 mm or more on each surface.
[0025] After the irradiation process, the photodetector 12 detects the reflected light of the irradiated laser beam and measures the phase of the reflected light (light receiving process). The detection result is transmitted to the computing unit 13.
[0026] In the first embodiment, the irradiation and light receiving steps are performed multiple times consecutively on the transported cast slab 2. That is, the laser beam is irradiated and the reflected light is detected at multiple longitudinal positions on the cast slab 2. There are no particular limitations on the positions where the laser beam is irradiated and the reflected light is detected, but it is preferable that they be set along the entire length of the cast slab 2 in the longitudinal direction, and they may be performed continuously at intervals of 50 mm or less on the cast slab 2.
[0027] After the light receiving step, the calculation unit 13 calculates the shape of the corner portion 21a based on the detection results from the light receiving step (shape calculation step). In the shape calculation step, first, the acquisition unit 131 acquires the detection results of the reflected light from the light receiving step. At this time, the acquisition unit 131 may also acquire the phase of the irradiated light from the irradiator 11.
[0028] Next, the distance calculation unit 132 calculates the distance to each irradiation position of the corner section 21a from the phase change between the irradiated light and the reflected light. Figure 4 shows an example of distance calculation at the corner section 21a shown in Figure 3. In this case, the distance calculation unit 132 may use the phase of the irradiated light acquired by the acquisition unit 131, or it may use a preset phase of the irradiated light.
[0029] Furthermore, the shape calculation unit 133 calculates the shape of the two surfaces of the corner portion 21a, the short side surface and the long side surface, from the calculated distances. In the first embodiment, the angle of the corner portion 21a is calculated as the shape of the two surfaces in the orthogonal cross-section at the longitudinal position where the laser beam is irradiated. Specifically, the distance data at multiple irradiation positions is classified into distance data for the short side 22 and distance data for the long side 23. Then, an approximate straight line is found for the multiple distance data for the short side 22 and the multiple distance data for the long side 23. After that, the angle of the corner portion 21a is determined by calculating the angle at the intersection of the two obtained approximate straight lines.
[0030] In the first embodiment, since the irradiation of the laser beam and the detection of reflected light are performed at multiple longitudinal positions, the shape calculation process is also performed for each of these multiple longitudinal positions. In other words, the angles of the corner portion 21a at multiple longitudinal positions are determined.
[0031] Furthermore, in the first embodiment, the angle of the corner portion 21a may be calculated at multiple longitudinal positions, and the average of the angles at the multiple longitudinal positions may be calculated as the final angle of the corner portion 21a. For example, if the angle of the corner portion 21a is calculated at longitudinal positions at 50 mm intervals, the average value at 1 m intervals may be calculated as the final angle of the corner portion 21a.
[0032] In the shape measurement method according to the first embodiment, the shapes of the two surfaces of the corner portion 21a, the short side 22a and the long side 23a, can be measured using a single irradiator 11 and receiver 12. This allows for accurate measurement of the shape of the corner portion 21a. Furthermore, in the shape measurement method according to the first embodiment, it is not necessary to use multiple irradiators and receivers when measuring the shapes of the two surfaces of the short side 22a and the long side 23a of a single corner portion 21a. In contrast, conventional methods that measure the shape of only one surface, such as the long side, require measuring the shape of the long side and the short side using separate devices and combining the measurement results to measure the shape of the corner portion. Such methods require multiple measuring devices to measure a single corner portion, and precise installation is necessary, making maintenance difficult. In addition, it is necessary to process information from multiple measuring devices, and as the measurement accuracy is increased, the amount of data to be processed increases, requiring a large-scale computing device. In contrast, the shape measurement method according to the first embodiment can reduce the number of measuring devices, thereby reducing the costs associated with maintenance and installation.
[0033] (Method for inspecting the surface quality of cast slabs) Next, a surface quality inspection method for the cast slab 2 according to the first embodiment will be described. In the surface quality inspection method for the cast slab 2 according to the first embodiment, the inspection is performed by evaluating the surface quality of the corner portion 21 of the cast slab 2 from the shapes of the two surfaces calculated in the shape calculation step (quality inspection step). Specifically, in the quality inspection step, the surface quality is evaluated by determining that there is an abnormality in the surface quality if at least one of the following cases is the angle of the corner portion 21a calculated in the shape calculation step is less than or equal to a first threshold of less than 90 degrees, or the angle is greater than or equal to a second threshold of more than 90 degrees. In addition, if at least one of the cases is the angle of the corner portion 21a being greater than the first threshold or less than the second threshold, it may be determined that there is no abnormality in the surface quality. If it is determined that there is an abnormality in the corner portion 21a, corner repair such as corner cutting may be performed before transporting the cast slab 2 to the next process.
[0034] If the angle of the corner portion 21a is less than 90 degrees, the corner portion 21a may be concave (the long or short side is recessed), which increases the likelihood of seam defects occurring in the rolled product. To accurately determine the likelihood of quality defects such as seam defects occurring, it is preferable to set the first threshold to 89 degrees or less. On the other hand, if the angle of the corner portion 21a is greater than 90 degrees, the corner portion 21a may be bulging (the long or short side is bulging), which increases the likelihood of quality defects such as surface defects occurring in the rolled product. To accurately determine the likelihood of quality defects occurring, it is preferable to set the second threshold to 100 degrees or more.
[0035] The surface quality inspection method for the cast slab 2 according to the first embodiment allows for accurate measurement of the corner portion 21a at a low cost, making it possible to predict the occurrence of surface defects such as seam defects in advance. Therefore, the occurrence of surface defects in the product can be suppressed.
[0036] <Second Embodiment> (Slab shape measuring device) The shape measuring device 1 for a cast slab 2 according to the second embodiment of the present invention will now be described. The shape measuring device 1 for a cast slab 2 according to the second embodiment has basically the same configuration as the shape measuring device 1 of the first embodiment, but the processing performed in the shape calculation unit 133 and evaluation unit 134 of the calculation device 13 is different.
[0037] (Method for measuring the shape of a cast slab) A method for measuring the shape of a cast slab 2 according to the second embodiment will now be described. In the second embodiment, first, an irradiation step and a light receiving step are performed, similar to the first embodiment. In the irradiation step, the irradiator 11 continuously irradiates the corner portion 21a of the conveyed cast slab 2 with a laser beam, thereby irradiating the cast slab 2 with a laser beam in multiple longitudinal directions along its entire length. In the light receiving step, the light receiver 12 continuously detects the reflected light of the laser beam irradiated at multiple longitudinal positions. The longitudinal positions where the laser beam is irradiated and the reflected light is detected are set according to the measurement accuracy caused by the size of surface defects, etc., and the shorter the measurement interval, the higher the accuracy of the measurement. For example, the laser beam irradiation and reflected light detection may be performed at constant intervals of about 0.5 mm along the longitudinal direction of the cast slab 2.
[0038] After the light receiving step, the calculation unit 13 calculates the shape of the corner portion 21a based on the detection results from the light receiving step (shape calculation step). In the shape calculation step, first, the acquisition unit 131 acquires the detection results of reflected light at multiple longitudinal positions in the light receiving step. At this time, the acquisition unit 131 may also acquire the phase of the irradiated light from the irradiator 11.
[0039] Next, the distance calculation unit 132 calculates the distance to each irradiation position of the corner portion 21a at multiple longitudinal positions from the phase change between the irradiated light and the reflected light. In other words, in the second embodiment, the profile in the orthogonal cross-section of the short side 22a and the long side 23a, as shown in Figure 4, is obtained at multiple longitudinal positions. When calculating the distance, the distance calculation unit 132 may use the phase of the irradiated light acquired by the acquisition unit 131, or it may use the phase of the irradiated light that has been set in advance.
[0040] Furthermore, the shape calculation unit 133 calculates the shapes of the two surfaces, the short side and the long side, of the corner portion 21a from the calculated distance. In the second embodiment, the three-dimensional shape profiles of the short side and the long side of the corner portion 21a are obtained as the shapes of the two surfaces. The three-dimensional shape profiles can be obtained, for example, by arranging the profiles of each orthogonal cross-section in the longitudinal direction.
[0041] (Method for inspecting the surface quality of cast slabs) Next, a surface quality inspection method for the cast slab 2 according to the second embodiment will be described. In the surface quality inspection method for the cast slab 2 according to the second embodiment, the surface quality of the corner portion 21a of the cast slab 2 is evaluated from the profile of the three-dimensional shape, which is the shape of the two surfaces calculated in the shape calculation step (quality inspection step). For example, in the quality inspection step, the surface quality is evaluated by determining that there is an abnormality in the surface quality if there are irregularities in the longitudinal direction of at least one of the long side surface and the short side surface of the corner portion 21a from the three-dimensional shape profile that are greater than a predetermined value.
[0042] Alternatively, for example, one-dimensional data in the longitudinal direction (data indicating the positions of multiple surfaces of the cast slabs 2 that are continuous in the longitudinal direction at a predetermined irradiation position) may be obtained from the 3D shape profile, and the surface quality may be evaluated from this one-dimensional data. In this case, if the difference between the average value of the one-dimensional data and the individual data corresponding to the longitudinal position exceeds a threshold, that is, if there are large irregularities at a specific position on the surface of the cast slab 2, it is detected as a location where surface defects are a concern (location of concern for defects). Then, detection of locations of concern for defects using one-dimensional data is performed for all areas (all irradiation positions) of the corner section 21a. Subsequently, for each of the short and long sides of the corner section 21a, if locations of concern for defects exist continuously along each surface for a predetermined length or longer, it may be determined that there is an abnormality in the surface quality. In this case, the predetermined length is set according to the size of the defect that is a problem.
[0043] In the shape measurement method according to the second embodiment, the shape of the corner portion 21a can be measured accurately at a low cost for the same reasons as in the first embodiment. Therefore, surface defects in the cast slab 2 can be detected with high accuracy.
[0044] <Variation> Although the present invention has been described above with reference to specific embodiments, this description is not intended to limit the invention. By referring to the description of the present invention, those skilled in the art will also see other embodiments of the invention, including various modifications, in addition to the disclosed embodiments. Accordingly, the embodiments of the invention described in the claims should be understood to include embodiments that include these modifications described herein, either individually or in combination.
[0045] For example, in the above embodiment, the shape of one corner portion 21a is measured, but the present invention is not limited to this example. For example, the shapes of multiple corner portions 21 may be measured simultaneously. In this case, the irradiator 11, the photodetector 12, and the cooling box 14 are provided at positions corresponding to the corner portions 21 to be measured, in the same manner as in the above embodiment, depending on the number of corner portions 21 to be measured. The calculation unit 13 also measures the shape of each corner portion 21 from the measurement results at each corner portion 21. Furthermore, for example, in addition to the shape of the corner portion 21, the overall length of at least one of the short side 22 and the long side 23 may also be measured. In this case, if the irradiator 11 and photodetector 12 that measure the distance to the corner portion 21 cannot measure the overall length of the short side 22 or the long side 23, an additional irradiator 11 and photodetector 12 for measuring only one side of the short side 22 or the long side 23 may be provided.
[0046] Furthermore, although the above embodiment involves measuring the shape of the cast slab 2 being transported by a transport device, the present invention is not limited to this example. For example, if the cast slab has completely solidified to the interior, the shape may be measured on the cast slab before it is cut by a continuous casting machine. Alternatively, the irradiator 11, the light receiver 12, and the cooling box 14 may be configured to move in the longitudinal direction of the cast slab 2, and the shape of the cast slab 2 while it is not moving may be measured. [Explanation of Symbols]
[0047] 1. Shape measuring device 11 Irradiator 12 Receiver 13 Arithmetic unit 131 Acquisition Department 132 Distance Calculation Unit 133 Shape calculation section 134 Evaluation Department 14 Cooling box 2 cast slabs 21,21a Corner section 22,22a Short side 23,23a Long side 3 Conveyor rollers
Claims
1. A method for measuring the shape of a cast slab, which has a rectangular cross-sectional shape in a cross-section perpendicular to the longitudinal direction, The irradiation step involves irradiating a planar laser beam at multiple irradiation positions on the short and long sides of the corner portion, A light receiving step for detecting the reflected light of the laser beam, A method for measuring the shape of a cast slab, comprising: a shape calculation step of calculating the shape of the two surfaces, the short side surface and the long side surface, at the corner portion by calculating the phase change of the reflected light and calculating the distance to the multiple irradiation positions.
2. The method for measuring the shape of a cast slab according to claim 1, wherein the shape calculation step involves calculating the angle of the corner portion in the cross-section as the shape of the two surfaces.
3. The method for measuring the shape of a cast slab according to claim 2, wherein the angle is calculated from the approximate straight line of the short side and the approximate straight line of the long side at the corner portion of the cross-section in the shape calculation step.
4. In the irradiation step, the laser beam is continuously irradiated onto multiple longitudinal positions of the cast slab. In the light receiving step, the reflected light of the continuously irradiated laser beam is continuously detected, The method for measuring the shape of a cast slab according to claim 1, wherein in the shape calculation step, the profile of the three-dimensional shape of the corner portion is determined as the shape of the two surfaces from the distances to the plurality of irradiation positions at the plurality of longitudinal positions.
5. A method for inspecting the surface quality of a cast slab, which evaluates the surface quality of the corner portion of a cast slab having a rectangular cross-sectional shape in a cross-section perpendicular to the longitudinal direction, The irradiation step involves irradiating a planar laser beam at multiple irradiation positions on the short and long sides of the corner portion, A light receiving step for detecting the reflected light of the laser beam, A shape calculation step which calculates the shape of the two surfaces, the short side surface and the long side surface, at the corner by calculating the phase change of the reflected light and the distance to the multiple irradiation positions, A quality inspection process for evaluating the surface quality of the corner portion based on the shape of the two surfaces, A method for inspecting the surface quality of a cast slab, comprising the following components.
6. In the shape calculation step, the angle of the corner portion in the cross-section is calculated as the shape of the two surfaces. The surface quality inspection method for a cast slab according to claim 5, wherein the quality inspection step determines that there is an abnormality in surface quality when the angle is less than or equal to a first threshold of less than 90 degrees, and when the angle is greater than or equal to a second threshold of more than 90 degrees.
7. In the irradiation step, the laser beam is continuously irradiated onto multiple longitudinal positions of the cast slab. In the light receiving step, the reflected light of the continuously irradiated laser beam is continuously detected, In the shape calculation step, the profile of the three-dimensional shape of the corner portion is determined as the shape of the two surfaces from the distances to the multiple irradiation positions at the multiple longitudinal positions, A method for inspecting the surface quality of a cast slab according to claim 5, wherein, based on the profile of the three-dimensional shape, it is determined that there is an abnormality in surface quality if there are irregularities in the longitudinal direction of at least one of the long side surface and the short side surface that exceed a predetermined value.
8. A cast slab shape measuring device for measuring the shape of the corner portion of a cast slab having a rectangular cross-sectional shape in a cross-section perpendicular to the longitudinal direction, An irradiator that irradiates a planar laser beam to multiple irradiation positions on the short and long sides of the corner portion, A light detector for detecting the reflected light of the laser beam, A slab shape measuring device comprising: a calculation device that calculates the phase change of the reflected light and the distance to the slab, thereby calculating the shape of the two surfaces, the short side surface and the long side surface, at the corner portion.