JP2009294012A - Apparatus and method for measuring board thickness - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus and a method for measuring a board thickness, capable of sensitively measuring a thickness value of a board, even in the case any oxide film is formed on a material to be measured. <P>SOLUTION: The method includes: an ultrasonic generating means 11 which irradiates the surface of the material to be measured 2 with a laser beam, thereby generating an ultrasonic wave and removing the oxide film; an ultrasonic detecting means 12 which is disposed on the downstream side in the conveying direction of the material to be measured 2; a material conveying means 14 for conveying the material to be measured 2; a control means 15 which carries out a control, thereby bringing the ultrasonic generating means 11 to irradiate a prescribed position of the material to be measured 2 with the laser beam and remove the oxide film, and after a movement of the prescribed position for a predetermined distance on the downstream side in the conveying direction of the material to be measured 2, which irradiates another prescribed position being positioned on the upstream side in the conveying direction on the basis of above prescribed position, with the laser beam to remove the oxide film, and further generates the ultrasonic wave and brings the ultrasonic detection means 12 to carry out a detection through the prescribed position; and an operation processing means 13 which calculates the board thickness of the material to be measured 2, based on a detection result of the ultrasonic detection means 12. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a plate thickness measuring apparatus and a plate thickness measuring method, and particularly preferably, irradiates a material to be measured with a laser to generate ultrasonic waves inside the material to be measured. The present invention relates to a plate thickness measuring apparatus and a plate thickness measuring method capable of measuring the plate thickness of a material to be measured in a non-contact manner by detecting an echo.

  As a device and a method for measuring the thickness of a material to be measured such as a steel material in a non-contact manner, there are, for example, a plate thickness measuring device and a plate thickness measuring method using an X-ray plate thickness meter or a γ-ray plate thickness meter. Are known. These thickness gauges have a transmitter and a receiver, and are provided so as to face each other with a material to be measured interposed therebetween. And the board | substrate thickness of a to-be-measured material can be measured by emitting X-rays and (gamma) rays from a transmission part, and receiving the emitted X-rays and (gamma) rays in a receiving part through a to-be-measured material.

  However, a plate thickness measuring device including an X-ray plate thickness meter or a γ-ray plate thickness meter is generally expensive. In addition, since X-ray thickness gauges and γ-ray thickness gauges contain radioactive materials, they must be handled with care. Therefore, compared to a plate thickness measuring device equipped with an X-ray plate thickness meter or a γ-ray plate thickness meter, it is desired to use a plate thickness measuring device equipped with a laser ultrasonic thickness meter that is inexpensive and easy to handle. There is a request.

  The outline of the thickness measurement method using a laser ultrasonic thickness gauge is as follows. First, a pulse laser is irradiated to a predetermined position on the surface of the material to be measured. When the pulse laser is irradiated, the surface of the material to be measured is deformed by a local temperature rise, and an elastic wave (ultrasonic wave) is generated. Further, ablation occurs on the surface of the material to be measured, and ultrasonic waves are generated inside the material to be measured due to the reaction force of the ablation. In this way, first, a laser beam is irradiated on the material to be measured to generate ultrasonic waves inside the material to be measured. The generated ultrasonic wave propagates through the material to be measured and reaches the surface of the material to be measured. This is detected in a non-contact manner using an ultrasonic detection device such as a laser interferometer. Based on the detected ultrasonic wave, the thickness of the material to be measured is calculated.

  By the way, in hot rolling of steel materials, the thickness of the rolled material after rolling or during rolling is measured in order to maintain the thickness of the rolled material (steel material, etc.) after rolling with a predetermined dimensional accuracy. In some cases, the sheet thickness is controlled by feeding back and adjusting the amount of rolling of the rolling roll so that the sheet thickness becomes a predetermined sheet thickness. For example, a plate thickness meter is disposed on the downstream side (outside of the rolled material) of the hot rolling mill, and the plate thickness of the rolled material is measured with this plate thickness meter. And the structure which compares the actual board thickness of a rolling material with the target board thickness, feeds back the difference, and controls the amount of rolling reduction of a rolling roll may be used. Thus, in hot rolling, it may be necessary to measure the thickness of a rolled material (such as steel).

  However, the following problems may occur when measuring the thickness of a hot-rolled rolled material using a laser ultrasonic thickness gauge. When a hot-rolled rolled material (that is, a high-temperature steel material or the like) is placed in the air, an oxide film is formed on the surface as time passes. Moreover, an oxide may adhere to the surface of the rolling material of hot rolling. When an oxide film is formed or an oxide adheres to the surface of a hot-rolled rolled material, such as a laser interferometer, the surface of the rolled material is irradiated with a laser to detect ultrasonic echoes. Since the laser is absorbed by the oxide film or oxide, it is difficult to detect the plate thickness.

JP 2002-213936 A

  In view of the above situation, the problem to be solved by the present invention is that the thickness of the material to be measured is measured by a laser ultrasonic thickness gauge even when an oxide film or the like is formed on the surface of the material to be measured. Can provide a thickness measuring device and a thickness measuring method, or in hot rolling, the thickness of a rolled material can be measured with a laser ultrasonic thickness gauge It is to provide a plate thickness measuring device and a plate thickness measuring method.

  In order to solve the above-described problems, the present invention provides a plate thickness measuring apparatus capable of measuring a plate thickness of a material to be measured in a non-contact manner while conveying the material to be measured, and irradiates the surface of the material to be measured with a laser. An ultrasonic wave generating means for generating an ultrasonic wave and ablating to remove an oxide film formed on the surface of the measured material; and a downstream side of the measured material in the conveying direction as viewed from the ultrasonic wave generating means. An ultrasonic detecting means for irradiating the surface of the measured material with a laser to detect the reflected wave; a measured material conveying means for conveying the measured material; the ultrasonic generating means; and the measured material The conveyance means and the ultrasonic detection means are controlled synchronously, and the ultrasonic wave generation means is irradiated with a laser at a predetermined position of the material to be measured to remove the oxide film, and the predetermined position Is a predetermined distance downstream in the conveyance direction of the material to be measured. After moving the laser beam, the ultrasonic wave generation means removes the oxide film and irradiates the ultrasonic wave by irradiating a laser to another predetermined position located upstream in the transport direction of the material to be measured as viewed from the predetermined position. And a control means for repeating the control for causing the ultrasonic detection means to detect the generated ultrasonic wave through the predetermined position, and the thickness of the material to be measured based on the detection result of the ultrasonic detection means. The gist of the present invention is to provide an arithmetic processing means for calculating.

  The present invention is also a plate thickness measurement method for measuring a plate thickness of a material to be measured in a non-contact manner while conveying the material to be measured, and (1) a laser is applied to a predetermined region on the surface of the material to be measured. A step of removing an oxide film formed on the surface of the material to be measured by ablating and generating ultrasonic waves, (2) a step of conveying the material to be measured by a predetermined distance, and (3) In step (1), the laser is irradiated to the other predetermined region upstream in the conveyance direction of the measured material in the region irradiated with the laser and ablated to remove the oxide film formed on the surface of the measured material. And (4) detecting an echo reflected on the bottom surface of the measured material through the region irradiated with the laser in the step (1). , The steps (1) to (5) It is an gist to return Ri.

  According to the present invention, when an ultrasonic wave is detected by a laser interferometer or the like, an oxide film or the like formed at a position where the laser of the laser interferometer is irradiated is previously ablated (removed). For this reason, when a laser interferometer is used for ultrasonic detection, it is possible to prevent or suppress the laser irradiated by the laser interferometer from being absorbed by an oxide film or the like. Therefore, even when an oxide film is formed on the surface of the material to be measured, such as a rolled material of hot rolling, it becomes possible to detect ultrasonic echoes with high sensitivity. The plate thickness can be measured.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  The plate thickness measuring apparatus according to the embodiment of the present invention can measure the plate thickness of a material to be measured by a laser ultrasonic method. Since the method of measuring the thickness of the material to be measured by the laser ultrasonic method is known, it will be briefly described below, and detailed description thereof will be omitted.

  FIG. 1 is a diagram schematically showing an outline of a configuration of a plate thickness measuring apparatus 1 according to an embodiment of the present invention. As shown in FIG. 1, a plate thickness measuring apparatus 1 according to an embodiment of the present invention includes an ultrasonic wave generating unit 11, an ultrasonic wave detecting device 12, an arithmetic processing unit 13, a measured material conveying unit 14, And control means 15. The ultrasonic wave generation means 11 can generate a pulse laser having a predetermined wavelength with a predetermined output. Then, the generated pulse laser can be irradiated on the surface of the material 2 to be measured. Various known laser generators can be applied to the ultrasonic generator 11.

  The ultrasonic detector 12 can measure minute vibrations (in other words, minute displacements) on the surface of the measurement target material 2. Various known displacement meters such as a laser interferometer can be applied to the ultrasonic detection device 12. For example, the laser interferometer includes a laser oscillator and an optical interferometer. The laser oscillator can continuously irradiate the surface of the material 2 to be measured with a laser having a predetermined output and a predetermined wavelength. The optical interferometer can detect a reflected wave of a laser (laser reflected on the surface of the material to be measured) irradiated by the laser oscillator on the surface of the material to be measured 2. Then, by detecting the laser reflected on the surface of the material to be measured 2, the absolute amount of minute vibration (minute displacement) on the surface of the material to be measured 2 can be measured.

  The measured material conveying means 14 can convey the measured material 2 in a predetermined direction. An arrow a in the figure indicates the conveyance direction of the material 2 to be measured. Then, the material to be measured 14 conveys the material 2 to be measured, so that the two materials to be measured can be moved relative to the ultrasonic wave generator 11 and the ultrasonic detector 12. Various known conveying means such as a roller conveyor can be applied to the measured material conveying means 14.

  The control means 15 can synchronously control the ultrasonic wave generation means 11, the ultrasonic wave detection means 12, and the measured material conveying means. As a result, the ultrasonic wave generation means can irradiate a predetermined position on the surface of the workpiece 2 to be conveyed (moved) with a pulse laser to generate an ultrasonic wave starting from the position of the writing height. Further, the ultrasonic detection means 12 can measure the absolute amount of minute vibration (minute displacement) at a predetermined position on the surface of the measured material 2 being conveyed (moved). The control means 15 can be a personal computer or a workstation.

  Based on the detection result of minute vibrations on the surface of the material to be measured 2 by the ultrasonic detector 12, the arithmetic processing means 13 irradiates the surface of the material to be measured 2 with a laser, The time until the sound echo is detected (that is, the propagation time of the ultrasonic wave) is measured. Based on the measured propagation time of the ultrasonic wave, the plate thickness of the material 2 to be measured is calculated. The same personal computer and workstation as the control means 15 can be applied to the arithmetic processing means 13.

  As shown in FIG. 1, the ultrasonic generator 11 and the ultrasonic detector (laser interferometer) 12 are arranged so as to irradiate the same surface of the material to be measured 2 with a laser. As shown in FIG. 1, the ultrasonic detection device (laser interferometer) 12 is disposed on the downstream side in the transport direction of the measurement target material 2 when viewed from the ultrasonic wave generation means 11. The ultrasonic detection device (laser interferometer) 12 can detect an ultrasonic wave by irradiating an ultrasonic detection laser to the same region as the region irradiated with the laser by the ultrasonic wave generation unit 11. it can.

  That is, when the measured material conveying means 14 conveys the measured material 2, the region on the measured material 2 irradiated with the laser at the moment when the ultrasonic wave generating means 11 is located is that of the measured material 2 over time. Move downstream in the transport direction. Since the ultrasonic detection device 12 is disposed on the downstream side in the conveyance direction of the material to be measured 2, when the measurement material 2 moves to the downstream side in the conveyance direction, the ultrasonic detection device 12 A laser for ultrasonic detection can be irradiated to the same region as the region where the generating means 11 has irradiated the laser.

  Next, a method for measuring the thickness of the material to be measured using the thickness measuring apparatus 1 according to the embodiment of the present invention will be described. FIG. 2 is a flowchart showing an outline of the flow of the plate thickness measuring method according to the embodiment of the present invention. 3 and 4 are diagrams schematically showing an outline of the flow of the plate thickness measuring method according to the embodiment of the present invention.

  From step S1 to step S4, the control means 15 is executed by synchronously controlling the ultrasonic wave generation means 11, the ultrasonic wave detection means 12, and the measured material conveying means 14. As shown in FIG. 2, in step S <b> 1, the measured material 2 is placed on the measured material conveying means 14, and the conveyance of the measured material 2 is started. An arrow a in the figure indicates the direction of conveyance of the material to be measured. When the measured material 2 is conveyed by the measured material conveying means 14, the measured material 2, the ultrasonic wave generating means 11 and the ultrasonic detection device 12 move relatively. The direction of this relative movement is not particularly limited, but is preferably a direction perpendicular to the thickness of the material 2 to be measured.

  In step S <b> 2, the ultrasonic wave generation unit 11 irradiates a specific region on the surface of the measurement target material 2 with a pulse laser under the control of the control unit 15. When the surface of the material to be measured is irradiated with a pulse laser, the oxide film formed on the surface of the region irradiated with the laser is removed by the ablation mechanism (see FIG. 3A).

  In step S3, after the material 2 to be measured is conveyed by a predetermined distance from the position of step S1 (in other words, the material 2 to be measured, the ultrasonic wave generating means 11 and the ultrasonic detector 12 are relative to each other by a predetermined distance. After the movement), the ultrasonic wave generation means 11 again irradiates a specific region on the surface of the material to be measured 2 with a pulse laser under the control of the control means 15. Specifically, as shown in FIG. 3B, the material to be measured 2 is conveyed by the material-to-be-measured conveying means 14, and the laser interferometer of the ultrasonic detection device 12 is operated by the ultrasonic wave generating means 11 and the laser is generated by the ultrasonic wave generating means 11. When reaching the position where the irradiated region can be detected, the surface of the material to be measured 2 is irradiated with a pulse laser.

  Since the material to be measured 2 is transported by the material to be measured transporting means 14 between the time when the ultrasonic wave generating means 11 irradiates the laser at step S2 and the time when the laser is again irradiated at step S3. The region where the sound wave generating means 11 irradiates the laser is different between step S2 and step S3. That is, the region irradiated with the laser in step S2 is downstream of the region irradiated with the laser in step S3 in the conveyance direction of the measurement target material 2.

  In step S3, when a predetermined region on the surface of the material to be measured 2 is irradiated with a laser, the oxide film formed on the surface of the material to be measured 2 is removed by the ablation mechanism. At the same time, due to the ablation mechanism and the thermoelastic effect, ultrasonic waves are generated starting from the region irradiated with the laser. The generated ultrasonic wave propagates inside the material to be measured 2 and is reflected on the bottom surface of the material to be measured 2 (the surface opposite to the surface irradiated with the laser). A part of the reflected ultrasonic wave reaches the region where the laser beam is irradiated and the oxide film is removed in step S2.

  In step S4, the ultrasonic detection device 12 detects minute vibrations (minute displacement) in the region where the laser beam is irradiated and the oxide film is removed in step S2. As described above, the ultrasonic wave generation unit 11 is identified at a timing when the laser interferometer of the ultrasonic wave detection device 12 can detect the minute displacement (microvibration) of the region irradiated with the laser beam in step S2. The laser is irradiated to the area. Therefore, the ultrasonic detection device 12 can detect an ultrasonic echo through the region from which the oxide film has been removed.

  In step S5, the arithmetic processing means 13 determines the ablation mechanism of the laser after the ultrasonic wave generation means 11 irradiates the surface of the material to be measured based on the detection result of the ultrasonic echo by the ultrasonic detection device 12. And the time until the bottom echo of the ultrasonic wave generated by the thermoelastic effect is detected (that is, the propagation time of the ultrasonic wave) is measured. That is, in step S3, after the ultrasonic wave generation means 11 irradiates a specific area on the surface of the measurement object 2 with a laser, in step S4, the ultrasonic detection device 12 detects the bottom echo of the ultrasonic wave. Measure time. And the arithmetic processing means 13 calculates the plate | board thickness of the to-be-measured material 2 based on the measured propagation time of the ultrasonic wave.

  When the measurement of the plate thickness of the material 2 to be measured is continued (that is, when the plate thickness is measured at a plurality of locations) (“Yes” in step S6), the process returns to step S3.

  After the material to be measured 2 is conveyed by a predetermined distance, the ultrasonic wave generation unit 11 irradiates a specific region on the surface of the material to be measured with a pulse laser under the control of the control unit 15. Specifically, as shown in FIG. 4, the laser irradiated region in the previous step S <b> 3 moves as the material to be measured 2 moves, and is emitted by the laser interferometer of the ultrasonic detector 12. The ultrasonic wave generation means 11 irradiates the laser at the timing when the region is irradiated. Therefore, the region irradiated with the laser in the current step S3 is different from the region irradiated with the laser in the previous step S3.

  In this step S3, when a predetermined region of the material to be measured 2 is irradiated with laser, the oxide film formed on the surface of the material to be measured 2 is removed by the ablation mechanism. At the same time, due to the ablation mechanism and the thermoelastic effect, ultrasonic waves are generated starting from the region irradiated with the laser. The generated ultrasonic wave propagates inside the material to be measured 2 and is reflected by the bottom surface of the material to be measured 2. A part of the reflected ultrasonic waves reaches the region where the laser beam was irradiated and the oxide film was removed in the previous step S3.

  In this step S4, the ultrasonic detection device 12 detects minute vibrations (minute displacements) in the region where the laser beam was irradiated and the oxide film was removed in the previous step S3. At a timing when the laser emitted from the laser interferometer of the ultrasonic detection device 12 irradiates the laser to the region that the ultrasonic generation unit 11 has lasered in the previous step S3, the ultrasonic generation unit 11 irradiates the specific region with the laser. To do. This timing is controlled by the control means 15. Therefore, the ultrasonic detection device 12 can detect an ultrasonic echo through the region from which the oxide film has been removed.

  In this step S5, the arithmetic processing means 13 irradiates the laser after the ultrasonic wave generating means 11 irradiates the surface of the material 2 to be measured based on the detection result of the ultrasonic echo by the ultrasonic detecting device 12. The time until the bottom echo of the ultrasonic wave generated by the ablation mechanism and the thermoelastic effect is detected (that is, the propagation time of the ultrasonic wave) is measured. That is, after the ultrasonic wave generation means 11 irradiates a specific area on the surface of the material 2 to be measured in step S3 this time, the ultrasonic detection device 12 generates the bottom echo of the ultrasonic wave in step S4. Measure the time until detection. And the arithmetic processing means 13 calculates the plate | board thickness of the to-be-measured material 2 based on the measured propagation time of the ultrasonic wave.

  Thus, when measuring the plate | board thickness of the several location of the to-be-measured material 2 continuously, operation | movement of step S3-step S5 is repeated. At this time, a region where the ultrasonic detection device 12 irradiates the laser in a certain step S4 is a region where the ultrasonic wave generation means 11 irradiates the laser in step S3 in the previous step.

  That is, in step S3 in the previous round, in order to generate ultrasonic waves, a predetermined region of the material to be measured 2 is irradiated with laser, and ultrasonic waves are generated by an ablation mechanism and a thermoelastic effect. At this time, the oxide film formed on the surface of the region irradiated with the laser is removed by an ablation mechanism. The region where the oxide film is removed by the ablation mechanism is set as a detection region in which the ultrasonic detection device 12 detects the bottom echo of the ultrasonic wave in the next round. Such an operation is repeated.

  According to such a configuration, it is possible to detect an ultrasonic echo through a region where the oxide film formed on the surface of the measurement target material 2 is ablated (removed). For this reason, when a laser interferometer is used for the detection of an ultrasonic echo, it can prevent or suppress that the laser which the laser interferometer irradiated is absorbed by an oxide film. Accordingly, even when an oxide film is formed on the surface of the material to be measured 2 as in hot rolling, it is possible to detect ultrasonic echoes with high sensitivity, and the plate thickness of the material to be measured 2 Can be measured.

  And if the plate | board thickness measuring apparatus 1 and the plate | board thickness measuring method concerning embodiment of this invention are applied to hot rolling, the plate | board thickness of the to-be-measured material 2 can be measured in-line. Therefore, it can be applied to the control of the thickness of the rolled material in hot rolling. Here, the plate thickness measuring apparatus 1 according to the embodiment of the present invention has a simple configuration and does not use a radioactive substance, so that it is inexpensive and easy to handle. Therefore, for example, the cost of the production line can be reduced.

  In addition, the plate | thickness of the specific position of the to-be-measured material 2 can be measured by performing operation | movement of step S1 to S5 shown in FIG. 2 only once. Further, by repeating step S3 to step S5 shown in FIG. 2, the plate thickness can be measured over the entire length of the workpiece 2 in the transport direction.

  It should be noted that in a certain step S3, a region where the laser is irradiated on the surface of the material 2 to be measured (that is, a region where the ultrasonic detection device 12 detects the bottom echo in the next round) and a next step S3. It is preferable that the distance from the region irradiated with the laser to generate the ultrasonic wave (hereinafter simply referred to as “laser irradiation interval”) is as follows.

  That is, the ultrasonic wave that reaches the region where the surface of the material 2 to be measured is irradiated with the laser beam in one step S3 from the region irradiated with the laser beam in the next step S3 is generated. There are those that propagate by reaching the surface of the material 2 to be measured and those that propagate inside the material 2 to be measured and reflected by the bottom surface. In the present invention, since it is necessary to detect an ultrasonic wave that propagates inside the material to be measured 2 and is reflected by the bottom surface, the ultrasonic wave that propagates through the surface of the material to be measured 2 and reaches the ultrasonic wave is detected. It is preferable not to overlap.

  It is known that the propagation speed of the ultrasonic wave propagating through the surface of the material to be measured 2 is smaller than the propagation speed of the ultrasonic wave propagating through the inside of the material to be measured 2. Further, the path of the ultrasonic wave propagating through the surface of the material to be measured 2 is shorter than the path of the ultrasonic wave propagating through the inside of the material to be measured 2 and reflected to the bottom surface. For this reason, depending on the value of the thickness of the material to be measured 2 and the value of the laser irradiation interval, the ultrasonic wave propagating through the surface of the material to be measured 2 and the ultrasonic wave propagating through the inside of the material to be measured 2 are approximately. At the same time, the ultrasonic detector may irradiate the laser and reach an area where the bottom echo of the ultrasonic wave is detected. Then, since the bottom echo and the ultrasonic wave propagating on the surface are detected in a combined state, it may be difficult to identify the bottom echo.

For this reason, it is preferable that the irradiation interval of the laser is set so that the time for the ultrasonic wave propagating through the surface of the material to be measured 2 to be different from the time for the ultrasonic wave propagating inside the material to be measured to arrive. Specifically, it is preferable not to satisfy d = 2 × (v ′ / v) × (T ² + (d / 2) ² ) ^(1/2) . Here, d is the laser irradiation interval, v ′ is the propagation speed of the ultrasonic wave propagating through the surface of the material to be measured 2, v is the propagation speed of the ultrasonic wave propagating inside the material to be measured 2, and T is the material to be measured. The plate thickness. If such a condition is not satisfied, the ultrasonic wave propagating through the surface of the material to be measured 2 and the ultrasonic wave propagating through the inside of the material to be measured can be prevented from overlapping. Therefore, since the ultrasonic wave propagating through the surface of the material to be measured 2 and the ultrasonic wave propagating through the inside of the material to be measured 2 are detected separately, the bottom surface echo can be detected with high sensitivity.

  Next, examples of the present invention will be described. Table 1 shows the implementation conditions in the examples of the present invention.

  The excitation laser for generating ultrasonic waves has a transmission wavelength of 1064 nm, a maximum transmission output of 430 mJ, a pulse width of 8 nsec, a transmission period of 10 Hz, and a beam diameter of 3 mm. The laser emitted from the laser interferometer of the ultrasonic detection apparatus has a transmission wavelength of 532 nm, a transmission output of 200 mJ, and a beam diameter of 50 μm. The material to be measured is S50C carbon steel, the plate thickness is 10 mm, and the plate width is 100 mm. The surface is glossy rolled skin. And it heats and uses at 1000 degreeC with a heating furnace. The distance between the material to be measured and the excitation laser is 450 mm.

  First, a predetermined region on the surface of the material to be measured was irradiated with an excitation laser, and the oxide film on the surface was removed by an ablation mechanism. Next, an excitation laser was irradiated to a region different from the region where the oxide film was removed, and ultrasonic waves were generated inside the material to be measured by an ablation mechanism and a thermoelastic effect. And the laser interferometer laser was irradiated to the area | region where the oxide film of the surface was removed, and the ultrasonic echo was detected.

  FIG. 5 is a graph showing the detection result of the ultrasonic echo according to the example of the present invention. 6 and 7 are graphs showing detection results of ultrasonic echoes according to the comparative example. Specifically, in the embodiment of the present invention, after removing the oxide film on the surface by the ablation mechanism, the excitation laser was irradiated to the area different from the area where the oxide film was removed, and the ultrasonic echo was measured. . In the comparative example shown in FIG. 6, after removing the oxide film on the surface by the ablation mechanism, the material to be measured is left in the atmosphere for 20 seconds, and then the excitation laser is irradiated to a region different from the region where the oxide film is removed. Ultrasonic echoes were measured. In the comparative example shown in FIG. 7, after removing the oxide film on the surface by the ablation mechanism, the material to be measured is left in the atmosphere for 30 seconds, and then an excitation laser is irradiated to a region different from the region where the oxide film is removed. Ultrasonic echoes were measured. In the comparative example, it is considered that an oxide film is formed on the surface of the material to be measured by leaving the material to be measured in the atmosphere for a predetermined time.

  5 and 6, the bottom echo is surrounded by an ellipse (in FIG. 7, no indication is given because it cannot be distinguished). As shown in FIG. 5, in the embodiment of the present invention, the bottom echo was clearly detected. On the other hand, in the comparative example shown in FIG. 6, the peak value of the bottom echo detected is small, and the detection sensitivity of the bottom echo is low. Moreover, in the comparative example shown in FIG. 7, the peak value of the bottom echo was hardly detected. Thus, according to the present invention, it was confirmed that the bottom surface echo can be measured with high sensitivity.

  While various embodiments and examples of the present invention have been described above, the present invention is not limited to the above-described embodiments or examples, and various modifications can be made without departing from the spirit of the invention. Needless to say.

  For example, in the above-described embodiment, when an oxide film is formed on the surface of the material to be measured, the oxide film is removed by laser irradiation. Thick foreign matter (for example, oxide) may adhere. In such a case, these foreign substances are removed by injecting high-pressure gas (such as air) or liquid (such as water) toward the surface of the material to be measured, and the oxidation formed on the surface of the material to be measured. The structure which removes a film | membrane by laser irradiation may be sufficient.

  In addition, since the oxide film formed on the surface of the material to be measured is thick, when the laser is irradiated, the oxide film is removed by the ablation mechanism, but no ultrasonic wave is generated (or only an ultrasonic wave with a small amplitude is generated). )Sometimes. In such a case, for example, it may be configured to irradiate the laser twice continuously, remove the oxide film by the first laser irradiation, and generate an ultrasonic wave by the second laser irradiation. . Note that the number of times of laser irradiation is not limited to two, but may be three or more. In this case, a configuration in which ultrasonic waves are generated by the last laser irradiation and the oxide film is removed by other laser irradiations can be applied.

It is the figure which showed typically schematic structure of the plate | board thickness measuring apparatus concerning embodiment of this invention. It is the flowchart which showed typically the flow of the measuring method of the board thickness concerning embodiment of this invention. It is the figure which showed typically the process of the measuring method of the board thickness concerning embodiment of this invention. It is the figure which showed typically the process of the measuring method of the board thickness concerning embodiment of this invention. It is the graph which showed the measurement result of the board thickness concerning the Example of this invention, and shows the detection result of an ultrasonic echo. It is the graph which showed the measurement result of the board thickness concerning a comparative example, and shows the detection result of an ultrasonic echo. It is the graph which showed the measurement result of the board thickness concerning a comparative example, and shows the detection result of an ultrasonic echo.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Plate | board thickness measuring apparatus 11 Ultrasonic wave generation means 12 Ultrasonic wave detection means 13 Operation processing means 14 Measured material conveyance means 15 Control means 2 Measured material

Claims (2)

A thickness measuring device capable of measuring the thickness of the material to be measured in a non-contact manner while conveying the material to be measured,
An ultrasonic generator for irradiating the surface of the material to be measured with a laser to generate ultrasonic waves and ablating to remove an oxide film formed on the surface of the material to be measured;
Ultrasonic detection means for irradiating the surface of the material to be measured, which is disposed downstream in the conveying direction of the material to be measured as viewed from the ultrasonic wave generation means, and detecting the reflected wave;
A measured material conveying means for conveying the measured material;
The ultrasonic generation means, the measured material conveying means, and the ultrasonic detection means are controlled synchronously, and the ultrasonic generation means is irradiated with a laser at a predetermined position of the measured material. After the oxide film is removed and the predetermined position moves a predetermined distance downstream in the conveyance direction of the material to be measured, the ultrasonic wave generation unit is upstream of the measurement material in the conveyance direction when viewed from the predetermined position. Control is performed by irradiating a laser to another predetermined position located on the side to remove the oxide film and generating an ultrasonic wave, and detecting the generated ultrasonic wave through the predetermined position by the ultrasonic detection means. Repetitive control means;
Arithmetic processing means for calculating the plate thickness of the material to be measured based on the detection result of the ultrasonic detection means;
A plate thickness measuring apparatus comprising: A thickness measuring method for measuring the thickness of the material to be measured in a non-contact manner while conveying the material to be measured,
(1) irradiating a predetermined region on the surface of the material to be measured with laser to remove the oxide film formed on the surface of the material to be measured and generating ultrasonic waves;
(2) conveying the material to be measured by a predetermined distance;
(3) Ablation is performed by irradiating a laser to another predetermined region on the upstream side in the conveyance direction of the material to be measured in the region irradiated with laser in the step (1), and is formed on the surface of the material to be measured. Removing the oxide film and generating ultrasonic waves;
(4) detecting an echo reflected from the bottom surface of the material to be measured among the generated ultrasonic waves through a region irradiated with the laser in the step (1);
A method for measuring a plate thickness, comprising repeating steps (1) to (5).

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