JP2018106592A - Carved character reading device and carved character reading method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a carved character reading device and carved character reading method for reading carved characters carved on a carving surface of steel, the device and method being able to reliably eliminate not only the influence of a disturbance element protruded from the carving surface of steel, such as a blister scale, but also the influence of a disturbance element recessed from the carving surface, such as a scratch made by a torch cutter.SOLUTION: In a carved character reading device, noise is removed from a three-dimensional distance map of a carving surface F, a surface state three-dimensional distance map of the carving surface F is calculated, and a threshold value based on the calculated surface state three-dimensional map of the carving surface is compared with the acquired three-dimensional distance map of the carving surface F to specify a mesh equal to or larger than the threshold value as a recessed mesh D. A carving target character PL that is a specific carved character in a carved character group LC is retrieved from a region where the specified recessed mesh D is present, and a carved character range P is determined and extracted based on the retrieved carving target character PL. In the extracted carved character range P, carved characters are cut out from the continuity of the recessed mesh D.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a stamped character reader and a stamped character reading method for reading a stamped character stamped on a stamped surface of a steel material, and particularly suitable for reading a stamped character stamped on a stamped surface of a steel material in a hot process of a steel mill. It is a thing.

As this type of conventional stamped character reading device, for example, the one shown in Patent Document 1 is known.
In the marking character reading device shown in Patent Document 1, three-dimensional distance information of the marking surface from the laser distance meter is acquired with a specified area resolution by a laser distance meter using a laser beam having a wavelength shorter than green, and the acquired marking surface Calculating the surface state including the undulation state in the height direction of the marking surface from the three-dimensional distance information as the surface state three-dimensional distance information of the marking surface, and the threshold value based on the calculated surface state three-dimensional distance information of the marking surface Compared with the acquired 3D distance information of the engraved surface, the area where the distance is greater than or equal to the threshold is specified as a recessed area, and a stamped character group is extracted from the identified area with the recessed area and extracted. A stamp character is cut out from the continuity of the recessed region in the stamp character group, and the cut character is compared with a pre-stored character to recognize the stamp character.

Japanese Patent Laid-Open No. 2006-146018

However, the stamped character reading device shown in this conventional patent document 1 has the following problems.
That is, in Patent Document 1, when calculating the surface state including the undulation state in the height direction of the marking surface from the acquired three-dimensional distance information of the marking surface, noise is calculated. Although it is removed, the noise is convex noise such as a floating scale protruding from the marking surface, and disturbance elements such as a torch cutter ridge recessed from the marking surface cannot be removed.

On the other hand, in Patent Document 1, the stamped character group is extracted from the identified existence region of the recessed region, but all the recessed region (region where the mesh with the recess exists) is extracted as the stamped character group. Therefore, disturbance elements such as a torch cutter ridge recessed from the marking surface are also recognized as a stamped character group, and the reading accuracy of the stamped character is low.
Accordingly, the present invention has been made to solve this conventional problem, and its purpose is not only the disturbance elements protruding from the marking surface of the steel material such as a floating scale, but also the concave surface from the marking surface such as the torch cutter rod. An object of the present invention is to provide a stamped character reading device and a stamped character reading method for reading a stamped character stamped on a stamped surface of a steel material, which can surely eliminate the influence of disturbance elements.

In order to solve the above-mentioned problem, a stamped character reading device according to one aspect of the present invention is a stamped character reading device that reads a stamped character that is stamped on a stamped surface of a steel material and that is recessed from the stamped surface. A three-dimensional distance information acquisition unit for acquiring three-dimensional distance information of the marking surface from the laser distance meter with a specified area resolution by a laser distance meter using a short laser beam, and three-dimensional distance information of the acquired marking surface A marking surface state calculation unit for calculating a surface state including a undulation state in the height direction of the marking surface as surface state three-dimensional distance information of the marking surface, wherein the undulation state in the height direction of the marking surface is Prior to the calculation of the surface state including, a marking surface state calculation unit that removes the convex portion of the marking surface as noise from the acquired three-dimensional distance information of the marking surface, and the surface state three-dimensional of the calculated marking surface Based on distance information And a region with a dent that identifies a region having a distance equal to or greater than the threshold as a region with a dent by comparing the threshold value with the acquired three-dimensional distance information of the engraved surface, and an existence region of the region with the specified dent From the stamp character group consisting of a series of stamp characters from the beginning to the end, search for the stamp target character that is a specific stamp character, determine the stamp character range based on the searched stamp target character, and extract A stamped character range extracting unit, a stamped character cutout unit that cuts out a stamped character from the continuity of the recessed region in the extracted stamped character range, and a character that is stored in advance as the cutout character The gist of the invention is that it includes a stamp character recognition unit that recognizes a stamp character by comparison.

  Further, a method for reading a stamped character according to another aspect of the present invention is a method for reading a stamped character that is stamped on a stamped surface of a steel material and that is recessed from the stamped surface, and uses a laser beam having a wavelength shorter than that of green. The three-dimensional distance information of the marking surface from the laser distance meter is acquired with a specified area resolution by a laser distance meter, and the convex portion of the marking surface is removed as noise from the acquired three-dimensional distance information of the marking surface. The surface state including the undulation state in the height direction of the marking surface from the three-dimensional distance information from which the noise has been removed is calculated as the surface state three-dimensional distance information of the marking surface, and the calculated surface state three-dimensional Compare the threshold value based on the distance information with the three-dimensional distance information of the acquired marking surface, identify the area where the distance is equal to or greater than the threshold value as a recessed area, and from the identified existence area of the recessed area A search is performed for a target stamp character that is a specific stamp character among a group of stamp characters that are formed by connecting a plurality of stamp characters from the beginning to the end, and a stamp character range is determined based on the searched target character. The gist of the present invention is to cut out a stamped character from the continuity of the dented region in the stamped character range, and compare the cutout stamped character with a previously stored character to recognize the stamped character.

According to the marking character reading device according to the present invention, the marking surface calculation unit calculates the surface state including the undulation state in the height direction of the marking surface from the acquired three-dimensional distance information of the marking surface. In addition to removing the convex part of the marking surface as noise, the marking character range extraction unit selects a specific character from a group of imprinted characters in which a plurality of imprinted characters are connected from the beginning to the end, Search for the stamped character that is the stamped character, determine the stamped character range based on the searched stamped character, extract it, and extract the stamped character range, and the extracted stamped character range will continue the dented region. Cut out the stamped characters from the sex. For this reason, not only disturbance elements protruding from the marking surface of steel materials such as floating scales, but also the influence of disturbance elements recessed from the marking surface such as torch cutters 疵 can be surely excluded. It is possible to provide a stamp character reading device that reads a stamp character.

It is a schematic block diagram which shows one Embodiment of the stamped character reader of this invention. It is a flowchart of the arithmetic processing for the stamp character reading performed with the arithmetic processing apparatus shown in FIG. It is a longitudinal cross-sectional view of the marking surface and marking character of steel materials. It is explanatory drawing of the three-dimensional distance map of the steel material marking surface acquired with the laser distance meter of FIG. It is explanatory drawing of the three-dimensional distance map of the marking surface state calculated by carrying out noise removal-smoothing by the moving average of the three-dimensional distance map of the steel material marking surface of FIG. It is explanatory drawing of the comparison with the threshold value on the basis of the three-dimensional distance map of the marking surface state of FIG. 5, and the three-dimensional distance map of a steel material marking surface. It is explanatory drawing of the mesh with a dent specified from the comparison result of FIG. It is explanatory drawing of the three-dimensional distance map which removed the data with big variation from the three-dimensional distance map of the steel material marking surface of FIG. It is explanatory drawing of the three-dimensional distance map of the marking surface state calculated by smoothing the three-dimensional distance map of the steel marking surface of FIG. 8 by the weighted least square method. It is explanatory drawing of the comparison with the threshold value on the basis of the three-dimensional distance map of the marking surface state of FIG. 9, and the three-dimensional distance map of a steel material marking surface. It is explanatory drawing of the mesh with a dent identified from the comparison result of FIG. It is explanatory drawing which shows the example from which the threshold value on the basis of the three-dimensional distance map of a marking surface state and the comparison of the three-dimensional distance map of a steel material marking surface differs. It is explanatory drawing of the mesh with a dent identified from the comparison result of FIG. It is a figure for demonstrating the existence area | region of a mesh with a dent, and the existence area | region of a mesh without a dent. It is a figure for demonstrating the stamped character range extracted from the presence area | region of a mesh with a dent. It is explanatory drawing of the character cut out from the mesh with a dent in the stamped character range.

The following embodiments exemplify apparatuses and methods for embodying the technical idea of the present invention, and the technical idea of the present invention is the material, shape, structure, arrangement, etc. of components. Is not specified as follows. The technical idea of the present invention can be variously modified within the technical scope defined by the claims described in the claims.
Hereinafter, an embodiment of a stamped character reader according to the present invention will be described with reference to the drawings. FIG. 1 is a front view showing a schematic configuration of the engraved character reading device of this embodiment, which is arranged at an entry side portion of a hot rolling process of a steel mill. The steel material S such as slab, bloom, billet, etc. fed to the hot rolling process is elongated in the right direction in FIG. 1, and the left end surface of the figure is the marking surface F, and the marking surface F from the marking surface F Recessed engraved letters are engraved. In this embodiment, the marking surface F of the steel material S is scanned with the laser distance meter 1, and the three-dimensional distance data of the marking surface F including the marking characters is acquired as, for example, a three-dimensional distance map (three-dimensional information).

  As the laser distance meter 1 of this embodiment, a laser distance meter using laser light having a wavelength shorter than that of green is used. The steel material S fed to the hot rolling process is red hot at a temperature of 600 ° C. or higher. If a general red laser beam is used, the marking surface of the steel material S is generated by the red wavelength component from the steel material S. F three-dimensional distance data cannot be acquired properly. Therefore, in the laser rangefinder 1 of this embodiment, a laser beam having a wavelength shorter than that of green is used so that three-dimensional distance data can be acquired even on the marking surface F of the red hot steel material S. For the green wavelength, for example, the wavelength 546.1 nm specified by the International Commission on Illumination is applied. Therefore, for example, blue or violet laser light having a shorter wavelength is used as the laser light of the laser rangefinder 1 of this embodiment.

  The laser rangefinder 1 deflects the laser beam into a fan shape by, for example, swinging the laser head, and detects two-dimensional, that is, the position information of the laser beam deflection direction and its reflection direction as distance data from the laser rangefinder. It is a two-dimensional laser rangefinder. In this embodiment, the deflection direction of the laser beam by the two-dimensional laser distance meter 1 is set in the vertical direction in FIG. 1, that is, the direction parallel to the paper surface, and the laser distance meter 1 is perpendicular to the paper surface by the moving device 2. By moving (scanning), the three-dimensional distance data of the marking surface F of the steel material S is detected to obtain a three-dimensional distance map. That is, the marking surface F of the steel material S is a three-dimensional distance map in which the position data in the height direction of the marking surface F is superimposed on the two-dimensional position data of the surface parallel to the marking surface F. The state is represented. Therefore, the acquired three-dimensional distance map represents the surface state of the marking surface F of the steel material S. For example, an existing linear guide device or the like is applied to the moving device 2 of the laser distance meter 1, whereby the laser distance meter 1 can be smoothly moved in the direction perpendicular to the paper surface of FIG. In this embodiment, by scanning the two-dimensional laser distance meter 1, the surface state of the marking surface F of the steel material S can be detected with a resolution of 0.3 mm mesh, for example.

  Laser beam deflection by the laser distance meter 1 and movement of the laser distance meter 1 by the moving device 2 are controlled by the laser distance meter control device 3, and the three-dimensional distance of the marking surface F of the steel S detected by the laser distance meter 1. The data is converted into a three-dimensional distance map by the laser distance meter controller 3. The laser distance meter control device 3 deflects the laser light of the laser distance meter 1 in the direction parallel to the paper surface of FIG. 1 as described above, and the laser distance meter 1 itself is set in the initial position in the direction perpendicular to the paper surface of FIG. The three-dimensional distance data acquired during this period is converted into a three-dimensional distance map of the marking surface F of the steel material S. The laser distance meter 1 and the laser distance meter control device 3 are controlled by a higher-order arithmetic processing device 4, and the arithmetic processing device 4 reads the engraved characters. The arithmetic processing unit 4 has an advanced arithmetic processing function constituted by a computer system or the like. That is, the stamped character reading device of this embodiment is constructed by arithmetic processing executed in the arithmetic processing device 4. Further, in this arithmetic processing unit 4, imprinted character information on the marking surface F of the steel S fed to the hot rolling process is input from a higher-level arithmetic processing unit (not shown).

FIG. 2 is a flowchart showing the arithmetic processing for marking reading executed by the arithmetic processing device 4. This calculation process is started, for example, by inputting an engraved character reading command by an operator. First, in step S1, the two-dimensional laser distance meter 1 is scanned, and the steel material S is scanned with a prescribed resolution, that is, 0.3 mm mesh (region). A three-dimensional distance map of the marking surface F is created.
Next, the process proceeds to step S2, in which noise is removed from the acquired three-dimensional distance map of the marking surface F, and the surface state of the marking surface F is calculated from the three-dimensional distance map from which noise has been removed. In this embodiment, since the engraved character is recessed from the engraving surface F, the convex portion protruding from the engraving surface F is only noise from the engraved character to be read. As will be described later, the marking surface F has a scale (floating scale) generated in the steel material manufacturing process as a convex portion in addition to the inclination, the curved surface, and the unevenness as the surface state. Therefore, in the three-dimensional distance map of the marking surface F, a convex portion (a portion having a small distance from the laser rangefinder 1) protruding from the marking surface F by a specified value or more is removed as noise. Then, the surface state of the marking surface F is calculated from the three-dimensional distance map from which noise has been removed in this way. The calculation of the surface state of the marking surface F includes smoothing by a moving average (smoothing filter) and curved surface regression analysis by a least square method, as will be described later.

Next, the process moves to step S3, and a mesh whose distance in the three-dimensional distance map of the marking surface F is greater than or equal to the threshold is identified as a mesh with a depression by threshold determination according to the calculated surface state of the marking surface F.
Next, the process proceeds to step S4, where the target character for engraving is searched from the identified existence area of the mesh with the depression, and the range of the imprinted character is determined and extracted based on the searched target character for engraving.

Here, the stamp target character is a specific stamp character among a group of stamp characters formed by connecting a plurality of stamp characters from the beginning to the end. In this embodiment, as shown in FIG. , The first stamped character in the stamped character group LC formed by connecting seven stamped characters from the beginning to the end. For example, the marking target characters are determined in advance as three types 0, 1, and 2.
Next, the process proceeds to step S5, where a stamped character is cut out from the continuity (including discontinuity) of the mesh with dents in the extracted stamped character range. In this embodiment, it is assumed that engraved characters exist in a region where the mesh with dents is continuous in the vertical, horizontal, and diagonal directions of the marking surface F, and when the adjacent mesh with dents is 2 mesh or more, separate. It is determined that the character is an engraved character. Steps S4 and S5 will be described in detail later.

Next, the process proceeds to step S6, where the cut stamped character is recognized as a character by model matching (pattern matching) with a character stored in advance.
Next, the process proceeds to step S7, where the recognized character is collated with the character from the higher-order processing unit, and the process returns.
In the arithmetic processing unit 4 in the present embodiment, step S1 constitutes a “three-dimensional distance information acquisition unit”, step S2 constitutes a “engraved surface state calculation unit”, and step S3 “depressed region identification” Step S4 constitutes a “stamped character range extracting portion”, step S5 constitutes a “stamped character extraction portion”, and step S6 constitutes a “stamped character recognition portion”.

  According to this calculation process, the two-dimensional laser rangefinder 1 is scanned to create a three-dimensional distance map of the marking surface F of the steel material S with a specified mesh, and then from the acquired three-dimensional distance map of the marking surface F. The surface state of the marking surface F is calculated from the three-dimensional distance map from which the convex noise is removed and the noise is removed. Thereby, the inclination state, curved surface state, and uneven state of the marking surface F itself are detected. Then, a threshold value corresponding to the calculated surface state of the marking surface F is compared with a three-dimensional distance map of the marking surface F, and a mesh whose distance from the laser rangefinder 1 is equal to or greater than the threshold value is specified as a mesh with a dent.

  This mesh with dents is indicated by a symbol D in FIG. 14, and may include a disturbance element N such as a torch cutter dent recessed from the marking surface in addition to the marking character group LC. For this reason, in order not to recognize the disturbance element N as the stamped character group LC, the stamp target character PL is searched from the specified existence region of the indented mesh D, and the stamped character character PL is used as a reference. A range P (see FIG. 15) is determined and extracted. Thereby, the disturbance element N is excluded.

  Then, in the extracted stamped character range P, the stamped character is cut out from the continuity (including discontinuity) of the mesh D with the depression (see FIG. 16). Recognized as characters by model matching (pattern matching). For example, when engraved characters are close to each other, it is difficult to recognize each engraved character, but if it is determined that the engraved character is independent in a portion where the concave mesh is discontinuous, the engraved character is cut out. It is possible to recognize the extracted stamped character by comparing it with model matching. Finally, the recognized character is collated with the character input from the host arithmetic processing unit. If the collation result is not appropriate, for example, the operator is notified of this.

  For example, when the surface state of the marking surface F in the actual steel material S is as shown in FIG. 3, the floating scale C peeled off from the marking surface F has a distance from the laser distance meter 1 as the marking surface F. Therefore, it is a noise when reading engraved characters that are recessed from the engraving surface F. By removing the convex noise, a remarkable convex change from the surface state of the marking surface F can be removed. Consider a case in which, for example, the two-dimensional distance map of the marking surface F in the laser beam deflection direction is as shown in FIG. That is, the three-dimensional distance map of the marking surface F may be considered that the two-dimensional distance map of the marking surface F as shown in FIG. 4 is connected in the direction perpendicular to the drawing sheet. In this three-dimensional distance map, it is considered that there is a dent of a stamped character in a portion where the distance from the laser rangefinder 1 is larger than the other portion by a certain amount or more. In addition, it is considered that a portion where the distance from the laser rangefinder 1 is smaller than the other portion by a specified value or more is convex noise such as a floating scale C.

  Therefore, FIG. 5 shows a smoothed three-dimensional distance map by moving average after removing the convex noise of FIG. For the smoothing by the moving average, for example, a weighted moving average can be used as well known. By smoothing the three-dimensional distance map in this way, the surface state of the marking surface F including the undulation state in the height direction of the marking surface F, that is, the tilt state, the curved surface state, and the uneven state can be detected. it can. A two-dot chain line in FIG. 6 is obtained by adding a prescribed threshold value based on the three-dimensional distance map of the surface state of the marking surface F. This threshold value and the three-dimensional distance map of the marking surface F in FIG. 4 are compared, and it is considered that the region where the distance from the laser rangefinder 1 is equal to or greater than the threshold value, that is, the mesh has a dent of the stamped character. Therefore, as shown in FIG. 7, a mesh whose distance is equal to or greater than a threshold is specified as a mesh with a depression.

  For detecting the surface state of the marking surface, regression surface analysis by the least square method can be used. For example, FIG. 8 is obtained by removing, as noise, distance data having a larger variation than the other parts of the three-dimensional distance map of FIG. The dent of the engraved character is also considered to be a part of noise when viewed from the original state of the engraving surface F. FIG. 9 shows a surface state obtained by performing regression analysis on the curved surface (curved in the drawing) of the three-dimensional distance map from which the noise is removed by the least square method. In that case, for example, when the least square method is used in which the weight is increased for a mesh having a high data density and the weight is set to a small value for a mesh having a low data density, the reliability of the surface state of the engraved surface F subjected to regression analysis is increased. . The two-dot chain line in FIG. 10 is obtained by adding a prescribed threshold value based on the three-dimensional distance map of the surface state of the marking surface F. Then, this threshold value is compared with the three-dimensional distance map of the marking surface F in FIG. 4, and as shown in FIG. 11, an area where the distance from the laser distance meter 1 is equal to or larger than the threshold value, that is, a mesh is specified as a concave mesh.

  As a method for comparing the three-dimensional distance map of the marking surface F with the threshold value, as a method other than the method described above, the distance data as the surface state of the marking surface F is subtracted from the acquired three-dimensional distance map, and the marking as shown by the solid line in FIG. It is also possible to acquire a three-dimensional distance map of the uneven state with respect to the surface state of the surface F and compare the threshold value with the three-dimensional distance map of the uneven state with respect to the surface state of the marking surface F. And thereby, as shown in FIG. 13, the mesh whose distance from the laser rangefinder 1 is more than a threshold value can be specified as a mesh with a dent.

  When the mesh with a dent is specified in this way, a matrix of a mesh D with a dent and a mesh with no mesh (a mesh without a dent) M is formed as shown in FIG. In this matrix, the region where the mesh D with the depression exists may include a disturbance element N that is recessed from the marking surface such as the torch cutter 疵 in addition to the marking character group LC. For this reason, in order not to recognize the disturbance element N as the stamped character group LC, the stamp target character PL is searched from the specified existence region of the indented mesh D, and the stamped character character PL is used as a reference. A range P (see FIG. 15) is determined and extracted.

A method for extracting the stamp character range P will be described below.
The stamp read by the stamp character reading device is stamped by a stamp device (not shown). First, as a precondition in the present embodiment, the stamp character group LC stamped by the stamp device has numbers in the horizontal direction. Are character strings that can be recognized as numbers of several digits (in this embodiment, 7 digits). Furthermore, in the marking device, the maximum number of digits (the leftmost character of the character string) is stamped with only 0, 1, or 2.

  As described above, since the first character is limited to some extent in the imprinted character group LC shown in FIG. 14 (for example, three types of 0, 1, and 2 in this embodiment). Then, the first stamp character in the stamp character group LC formed by connecting a plurality of (seven) stamp characters from the beginning to the end is set as a stamp target character PL. Then, the head character as the marking target character PL is searched from the identified region of the mesh D with the dent. Specifically, pattern matching of three types of characters “0”, “1”, and “2” is performed in the specified existence region of the mesh D with the dent. In the case shown in FIG. 14, since the stamp character group LC is “3192202”, the first stamp character “3”, the second stamp character “1” from the head, and the fourth stamp character “2” from the head The fifth stamp character “2” from the beginning and the last stamp character “2” are searched by pattern matching. In this case, since there are five candidates as the marking target character PL, the first marking character “3” is set as the marking target character PL.

  Then, taking the leading character as the marking target character PL as a reference, the size of the stamped character in the stamped character group LC, the interval of the stamped character in the stamped character group LC, and the number of digits of the stamped character (in this embodiment, seven digits) are considered. Then, the stamped character range P including the stamped character group LC is determined and extracted. Here, on the specification of the stamping machine, there is no variation in the size of the stamped character in the stamped character group LC and the interval of the stamped character in the stamped character group LC, and the number of digits of the stamped character is a predetermined fixed digit. The stamp character range P can be easily determined and extracted. Thus, by determining and extracting the marking character range P, the disturbance element N that is recessed from the marking surface F such as a torch cutter can be excluded.

  When the stamped character range P is extracted, in the extracted stamped character range P, there is a stamped character in a region where the mesh D with dents is continuous in the vertical, horizontal, and diagonal directions. Since it is considered that the stamped characters are independent in the continuous region, as shown in FIG. 16, the stamped characters are cut out from the region of the independent mesh D with the depression (in the case shown in FIG. 16, “3”, “1” ”,“ 9 ”,“ 2 ”,“ 2 ”,“ 0 ”,“ 2 ”are cut out), and a known model matching (pattern matching) technique is used to recognize the character.

  As described above, in the stamped character reading device of this embodiment, in step S1 (three-dimensional distance information acquisition unit), the laser distance meter 1 using the laser light having a wavelength shorter than green emits the laser distance meter 1 from the laser distance meter 1 with a specified mesh resolution. A three-dimensional distance map of the marking surface F is acquired. Then, in step S2 (engraved surface state calculation unit), the surface state including the undulation state in the height direction of the marking surface F from the acquired three-dimensional distance map of the engraved surface F is obtained. Calculate as a map. Further, in step S3 (recessed area specifying unit), the calculated surface state three-dimensional distance map of the marking surface F is used as a reference, and the obtained three-dimensional distance map of the marking surface F is compared with a threshold to determine the distance. A mesh that is equal to or greater than the threshold is identified as a mesh D with a dent. When the concave mesh D is identified in this way, in step S4 (engraved character range extraction unit), a stamped character formed by connecting a plurality of stamped characters from the beginning to the end from the existence region of the concave mesh D. A search is made for a stamp target character PL which is a specific stamp character in the group LC, and a stamp character range is determined and extracted based on the searched stamp target character PL. Then, in step S5 (engraved character extracting unit), in the extracted engraved character range P, the engraved character is extracted from the continuity (including discontinuity) of the mesh D with the depression, and in step S6 (engraved character recognizing unit), The stamped character is recognized by comparing the cut stamped character with a previously stored character. Thereby, the marking character of the marking surface of the red hot steel material of 600 ° C. or higher can also be read.

  Then, in step S3 (a recessed area specifying unit), prior to calculating the surface state including the undulation state in the height direction of the marking surface, the convex portion of the marking surface is obtained from the acquired three-dimensional distance information of the marking surface. In addition to removing as noise, in step S4 (engraved character range extraction unit), a specific engraving from among the engraved character group LC in which a plurality of engraved characters are connected from the beginning to the end from the region where the mesh D with the depression is identified. A search is performed for the target stamp character PL, which is a character, and a stamp character range P is determined and extracted with reference to the target stamp character PL that has been searched, and the extracted stamp character range P is extracted in step S5 (a stamp character extraction unit). In FIG. 5, a stamped character is cut out from the continuity of the mesh D with the dent. For this reason, not only the disturbance element which protrudes from the marking surface F of steel materials, such as the floating scale C, but the influence of the disturbance element N dented from the marking surface F, such as a torch cutter rod, can be excluded reliably.

In the present embodiment, the stamp target character PL is the first stamp character in the stamp character group LC. Therefore, when there are a plurality of candidates as the stamp target character PL, the first stamp character is the stamp target character. PL may be used, and the marking target character PL can be searched without imposing a burden on the arithmetic processing of the arithmetic processing unit 4.
Further, in step S7, by comparing the recognized stamped character with the stamped character information acquired from the host processor, it is possible to avoid, for example, erroneous feeding of the steel material S to the hot rolling process. It becomes.
As mentioned above, although embodiment of this invention has been described, this invention is not limited to this, A various change and improvement can be performed.

  For example, the stamp target character PL does not necessarily need to be the first stamp character in the stamp character group LC, and may be a specific stamp character in the stamp character group LC. In this case, of course, when marking is performed by the marking device, it is necessary to mark the specific marking character with the marking target character PL. Further, the characters used as the engraved characters are not limited to numerals, and alphabets, kanji, kana characters, and the like can also be used. When the marking target character PL is the last marking character in the marking character group LC, if there are a plurality of candidates as the marking target character PL, the last marking character is designated as the marking target character PL. What is necessary is just to search the marking target character PL, without imposing a burden on the arithmetic processing of the arithmetic processing unit 4.

1 Laser rangefinder (two-dimensional laser rangefinder)
2 Moving device 3 Laser distance meter control device 4 Arithmetic processing device S Steel (slab)
F Engraved surface L Engraved letter C Floating scale D Dent mesh M Undented mesh P Engraved character range PL Engraved target character LC Engraved character group

Claims (4)

A stamp character reading device that reads a stamp character stamped on a stamp surface of a steel material and recessed from the stamp surface,
A three-dimensional distance information acquisition unit for acquiring three-dimensional distance information of the marking surface from the laser distance meter with a specified area resolution by a laser distance meter with a laser beam having a wavelength shorter than green;
A marking surface state calculating unit that calculates a surface state including a undulation state in the height direction of the marking surface from the acquired three-dimensional distance information of the marking surface as surface state three-dimensional distance information of the marking surface, Prior to calculation of the surface state including the undulation state in the height direction of the marking surface, a marking surface state calculation unit that removes the convex portion of the marking surface as noise from the acquired three-dimensional distance information of the marking surface;
Comparing a threshold value based on the calculated surface state three-dimensional distance information of the marking surface with the acquired three-dimensional distance information of the marking surface, there is a depression that identifies a region where the distance is greater than or equal to the threshold value as a region with a depression An area identification unit;
A search is performed for a stamp target character that is a specific stamp character from a group of stamp characters in which a plurality of stamp characters are connected from the beginning to the end from the region where the specified depression is present. A stamp character range extraction unit that determines and extracts a stamp character range as a reference; and
In the extracted stamped character range, a stamped character cutout unit that cuts out a stamped character from the continuity of the recessed area,
A stamped character reader comprising a stamped character recognition unit that recognizes a stamped character by comparing the cut stamped character with a previously stored character.   2. The stamp character reading apparatus according to claim 1, wherein the stamp target character is a first or last stamp character in the stamp character group. A stamp character reading method for reading a stamp character stamped on a stamp surface of a steel material and recessed from the stamp surface,
Obtain the three-dimensional distance information of the marking surface from the laser distance meter with a specified area resolution by a laser distance meter with a laser beam having a wavelength shorter than green,
The convex portion of the marking surface is removed as noise from the acquired three-dimensional distance information of the marking surface,
The surface state including the undulation state in the height direction of the marking surface from the three-dimensional distance information from which the noise has been removed is calculated as the surface state three-dimensional distance information of the marking surface,
Compare the calculated threshold value based on the three-dimensional distance information of the surface state with the three-dimensional distance information of the acquired marking surface to identify a region where the distance is equal to or greater than the threshold value as a region with a depression,
From the identified existence area of the dented area, a search is performed for a stamp target character that is a specific stamp character among a group of stamp characters including a plurality of stamp characters from the beginning to the end. Determine the stamp character range as a reference,
In the determined engraved character range, the engraved character is cut out from the continuity of the recessed area,
A method for reading a stamped character, wherein the stamped character is recognized by comparing the cut stamped character with a previously stored character.   4. The method for reading stamp characters according to claim 3, wherein the stamp target character is a first or last stamp character in the stamp character group.

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