JP2020153883A - Surface shape evaluation device, surface shape evaluation system, and surface shape evaluation method - Google Patents

Abstract

To evaluate the surface irregularity of a base metal substrate of a non-metal layer.SOLUTION: The present invention comprises: terahertz wave measuring means including a terahertz wave transmit unit which is capable of irradiating a prescribed position on surface of an object provided with a non-metal layer on the top layer of a metal substrate with a terahertz wave and scanning the surface, and a terahertz wave receive unit for receiving the terahertz wave reflected at the prescribed position of the object and scanning the surface of the object in association with coordinates; and means, constituted so as to be capable of deriving the distance between the terahertz wave measuring means and the surface of the metal substrate on the basis of the received data of the terahertz wave received by the terahertz wave receive unit, for generating the B scope data of the surface of the metal substrate on the basis of the derived distance, correcting the B scope data so that each of portions corresponding to the sound part of at least two mutually separate points on the surface of the metal substrate that are included in the generated B scope data approximately equals a virtual reference line corresponding to the scan line of the terahertz wave measuring means, and evaluating the surface irregularity of the metal substrate.SELECTED DRAWING: Figure 1

Description

The present invention relates to a surface shape evaluation device, a surface shape evaluation system, and a surface shape evaluation method for evaluating the shape of a base of a non-metal layer using a terahertz wave.

In recent years, research and development of terahertz wave imaging and radar have been carried out, and their application to non-destructive inspection and sensing is expected. Most of the terahertz waves are transmitted when irradiated with a non-metal material such as resin, while most of them are reflected when irradiated with a metal material. Conventionally, by utilizing such properties of terahertz waves, an evaluation object in which a non-metal layer such as a resin is provided as an anticorrosion layer on the upper layer of a metal substrate can be evaluated without removing the non-metal layer. Techniques for measuring the surface properties of a metal substrate, specifically, for example, anomalies that are thinned due to corrosion and become uneven, are being studied. For example, Non-Patent Document 1 describes an imaging device using an electronic device method of a reflective optical system using a resonance tunneling diode (RTD), which can perform two-dimensional imaging by utilizing the properties of terahertz waves. Is disclosed.

Jun Yamaguchi, "Development of Terahertz Imaging System", PIONEER R & D (2014)

By the way, in order to measure the surface properties of the metal substrate under the non-metal layer, the surface of the evaluation object is scanned one-dimensionally or two-dimensionally while irradiating the surface of the evaluation object with a terahertz wave to detect the reflected wave. There is a need. In this case, it is necessary to install a mechanism for scanning the terahertz transmission / reception head (hereinafter referred to as the transmission / reception head) for transmitting and detecting the terahertz wave in one dimension or two dimensions on the surface of the evaluation object.

As a mechanism for scanning the transmission / reception head in one dimension, a linear scanning mechanism in which the transmission / reception head moving in the uniaxial direction is supported and fixed by a fixing jig such as a leg shape can be considered. In the linear scanning mechanism, a fixing jig is provided in the linear operating mechanism, and the fixing jig is pressed against the surface of the evaluation object to be fixed. As a result, when scanning the transmission / reception head, it is possible to minimize the fluctuation of the distance between the surface of the evaluation object and the transmission / reception head, and to prevent the transmission / reception head from deviating from a predetermined measurement scanning line.

As a mechanism for scanning the transmission / reception head in two dimensions, a plane scanning mechanism in which the transmission / reception head is mounted on a two-axis scanner or the like and a fixing jig is attached to the scanner can be considered. Also in the flat scanning mechanism, the moving surface of the transmission / reception head is fixed so as to face the surface of the evaluation target by the fixing jig, so that the surface of the evaluation target and the transmission / reception head are scanned when the transmission / reception head is scanned. The fluctuation of the distance with and can be minimized. With such a scanning mechanism, the position of the transmission / reception head at the time of measurement can be accurately performed.

However, in general, the surface of a structure made of a metal substrate is provided with a non-metal layer made of a coating film such as a resin or a coating film for corrosion protection. The thickness of the non-metal layer is not uniform along the surface of the structure, and the surface of the non-metal layer is often uneven or inclined (hereinafter, uneven or the like). When the fixing jig of the scanning mechanism described above is mounted on the anticorrosion layer having such unevenness, the wave transmitting / receiving head may not be able to scan parallel to the surface of the metal substrate which is the base of the non-metal layer. .. Further, when the thickness of the non-metal layer is non-uniform, it becomes difficult to keep the distance between the wave transmitting / receiving head and the surface of the evaluation object constant. In the measurement by the scanning mechanism in such an installed state, the unevenness of the surface of the evaluation object, that is, the surface of the non-metal layer is superimposed on the fluctuation of the distance between the wave transmitting / receiving head and the surface of the metal substrate due to the installed state. The measurement will be performed in this state. Therefore, it is difficult to evaluate only the unevenness of the surface of the metal substrate. In particular, when the entire scanning mechanism is moved in order to change the measurement range, that is, when the so-called refilling is performed, the influence of the unevenness of the surface of the evaluation object, that is, the surface of the non-metal layer becomes remarkable. When evaluating the unevenness of the surface of a metal substrate from the measurement results under such influence, the operator who performs the evaluation virtually sets the reference line and reference plane for evaluation, so the measurement result There is a problem that variation is likely to occur. Therefore, when evaluating the unevenness of the surface of the underlying metal substrate without removing the non-metal layer for the evaluation object in which the non-metal layer is formed on the surface of the metal substrate, the surface of the evaluation object, That is, there has been a demand for a technique capable of eliminating the influence of the unevenness of the surface of the non-metal layer and accurately measuring and evaluating the unevenness of the surface of the metal substrate.

The present invention has been made in view of the above, and an object of the present invention is to irradiate an evaluation object having a non-metal layer on the upper layer of a metal substrate with a terahertz wave from the non-metal layer side to irradiate the non-metal layer. It is an object of the present invention to provide a surface shape evaluation device, a surface shape evaluation system, and a surface shape evaluation method capable of accurately evaluating the unevenness of the surface of the underlying metal substrate without removing the above-mentioned material.

(1) In order to solve the above-mentioned problems and achieve the object, the surface shape evaluation device according to one aspect of the present invention is placed at a predetermined position on the surface of an object in which a non-metal layer is provided on an upper layer of a metal substrate. A terahertz wave transmitter that can irradiate a terahertz wave and can scan the surface of the object, and a terahertz wave that is reflected at the predetermined position of the object and can receive the terahertz wave. Based on a terahertz wave measuring means provided with a terahertz wave receiver capable of scanning while associating the surface with coordinates, and terahertz wave reception data received by the terahertz wave receiver in a portion scanning the surface of the object. The distance between the terahertz wave measuring means and the surface of the metal substrate can be derived, and B-scope data on the surface of the metal substrate is generated based on the derived distance and included in the generated B-scope data. The B scope data is set so that the portions corresponding to at least two sound portions of the surface of the metal substrate separated from each other are substantially equal to the virtual reference line corresponding to the scanning line of the terahertz wave measuring means. It is characterized by comprising an analysis means for correcting and evaluating the unevenness of the surface of the metal substrate.

(2) The surface shape evaluation device according to one aspect of the present invention is the first scan obtained by performing the scan by the terahertz wave measuring means in the uniaxial direction in the above invention (1). After moving the 1B scope data and the terahertz wave measuring means along the other axis direction which is not parallel to the uniaxial direction, the second scanning which executes scanning by the terahertz wave measuring means substantially parallel to the uniaxial direction. With respect to the second B scope data obtained by the above, the distance between the terahertz wave measuring means of the sound part in the first B scope data and the terahertz wave measuring means of the sound part in the second B scope data. It is characterized in that the first B scope data and the second B scope data are corrected so that the distances are equal to each other.

(3) The surface shape evaluation system according to one aspect of the present invention is configured to be capable of irradiating a terahertz wave at a predetermined position on the surface of an object provided with a non-metal layer on the upper layer of the metal substrate, and the object. A terahertz wave transmitting unit capable of scanning the surface, and a terahertz wave receiving unit capable of receiving the terahertz wave reflected at the predetermined position of the object and scanning while associating the surface of the object with coordinates. The distance between the terahertz wave measuring means and the surface of the metal substrate based on the terahertz wave measuring means provided with the above and the terahertz wave received data received by the terahertz wave receiving unit in the portion where the surface of the object is scanned. Is configured to be derivable, B-scope data on the surface of the metal substrate is generated based on the derived distance, and at least two soundnesses of the surface of the metal substrate included in the generated B-scope data are separated from each other. The B scope data is corrected and the unevenness of the surface of the metal substrate is evaluated so that the portions corresponding to the portions are substantially equal to the virtual reference line corresponding to the scanning line of the terahertz wave measuring means. The analysis means is configured to be able to send and receive the received data via the network.

(4) In the surface shape evaluation method according to one aspect of the present invention, the terahertz wave measuring means scans the surface of an object having a non-metal layer on the upper layer of the metal substrate and irradiates the terahertz wave at a predetermined position. In the step, the reception step received by the terahertz wave measuring means while associating the terahertz wave reflected at the predetermined position on the object with the coordinates of the surface of the object, and the portion where the surface of the object is scanned. Based on the received data of the terahertz wave received by the terahertz wave measuring means, the distance between the terahertz wave measuring means and the surface of the metal substrate is derived, and based on the derived distance, B on the surface of the metal substrate is derived. The B scope data generation step for generating the scope data and the portion corresponding to at least two sound parts of the surface of the metal substrate included in the B scope data generated in the B scope data generation step are separated from each other. It includes an evaluation step of correcting the B scope data and evaluating the unevenness of the surface of the metal substrate so that the distance is substantially equal to the virtual reference line corresponding to the scanning line of the terahertz wave measuring means. It is a feature.

According to the surface shape evaluation device, the surface shape evaluation system, and the surface shape evaluation method according to the present invention, an evaluation object having a non-metal layer on the upper layer of a metal substrate is irradiated with a terahertz wave from the non-metal layer side. When evaluating the surface properties of the underlying metal substrate without removing the non-metal layer, it is possible to accurately evaluate the uneven properties of the surface of the metal substrate.

FIG. 1 is a block diagram showing a configuration of a surface shape evaluation device according to an embodiment of the present invention. FIG. 2 is a schematic view for explaining a problem when the non-metal layer is inclined with respect to the steel surface in the evaluation method according to the prior art. FIG. 3 is a schematic diagram for explaining a problem when the thickness distribution of the non-metal layer is non-uniform in the evaluation method according to the prior art. FIG. 4 is a schematic view for explaining a state in which the scanning direction of the terahertz wave transmitting / receiving head is inclined with respect to the steel surface. FIG. 5 is a schematic diagram for explaining a method of extracting a sound portion of a steel surface in an evaluation object in the evaluation method according to the embodiment of the present invention. FIG. 6 is a schematic diagram for explaining a method of correcting inclination in the evaluation method according to the embodiment of the present invention. FIG. 7 is a schematic diagram for explaining a method of correcting inclination in the evaluation method according to the embodiment of the present invention. FIG. 8 is a schematic diagram for explaining a problem when a scanner equipped with a terahertz transmission / reception head is rearranged on an object. FIG. 9 is a schematic diagram for explaining a method of correcting in the vertical direction with respect to the measurement surface in the evaluation method according to the embodiment of the present invention. FIG. 10 is a schematic diagram for explaining a method of correcting in the vertical direction with respect to the measurement surface in the evaluation method according to the embodiment of the present invention. FIG. 11 is a plan view showing a scanner according to a modified example of the embodiment of the present invention.

Hereinafter, the surface shape evaluation device and the surface shape evaluation method according to the embodiment of the present invention will be described with reference to the drawings. In all the drawings of the following embodiment, the same or corresponding parts are designated by the same reference numerals. Moreover, the present invention is not limited to one embodiment described below.

First, a surface shape evaluation device according to an embodiment of the present invention will be described. FIG. 1 is a block diagram showing a configuration of a surface shape evaluation device 1 according to an embodiment of the present invention. As shown in FIG. 1, the surface shape evaluation device 1 according to the present embodiment includes a terahertz wave transmission / reception head 10, a scanner 30, a terahertz transmission / reception controller 40, a scanner controller 60, and an analysis control unit 70. To.

The object 80, which is an evaluation object evaluated by the surface shape evaluation device 1, is provided with an anticorrosion layer 82 for the purpose of anticorrosion on the surface (hereinafter, steel surface 81a) of the steel material 81 as a metal substrate. The anticorrosion layer 82 is made of a non-metal layer such as a coating film or a resin. The surface shape evaluation device 1 evaluates the steel surface 81a of the steel material 81 by irradiating the object 80 with a terahertz wave from the anticorrosion layer 82 side. The object 80 is a member whose surface 82a is a planar member, and is various objects in which a non-metal layer is formed on the surface of a metal substrate made of a metal material such as a steel structure, and is a flat surface such as a bridge. It can be a member or various members such as a cylindrical or columnar member such as a pipe.

The transmission / reception head 10 as a terahertz wave measuring means is configured to be able to irradiate the surface of the object 80 with the terahertz wave, and is composed of a reflection type terahertz wave measuring device configured to be able to detect the reflected terahertz wave. Will be done. That is, the transmission / reception wave head 10 has both a terahertz wave transmitting means and a terahertz wave receiving means. Here, the terahertz wave is an electromagnetic wave belonging to the so-called terahertz region, which is a frequency region of about 1 terahertz (1 THz = 10 ¹² Hz), specifically, 100 GHz to 10 THz (10 ¹¹ Hz to 10 ¹³ Hz). The terahertz region is a frequency region that has both the straightness of light and the transmission of electromagnetic waves. In the present embodiment, the frequency of the terahertz wave can be selected according to the thickness of the anticorrosion layer 82 on the surface of the object 80, and is preferably 0.3 THz or more and 0.6 THz or less, but is not necessarily limited to this range. It's not something.

The transmission / reception head 10 includes a terahertz wave transmitting unit 11 as a terahertz wave transmitting means, a beam splitter 12, an objective lens 13, and a terahertz wave receiving unit 14 as a terahertz wave receiving means. The terahertz wave transmitting unit 11 which is a transmitting optical system includes, for example, a terahertz wave generating element 111 including a resonance tunneling diode (RTD) that oscillates CW, a hemispherical lens 112, a collimating lens 113, and the like. It is configured to have a shutter 114. The terahertz wave receiving unit 14 as a receiving optical system includes a condensing lens 141, a hemispherical lens 142, and a terahertz wave detecting element 143.

Here, instead of the surface shape evaluation device 1 using the RTD as the terahertz wave generating element 111, a surface shape evaluation device using a photo conductive antenna (PCA) that performs pulse oscillation may be adopted. When PCA is used as the terahertz wave generating element 111, it is preferable to use PCA also for the terahertz wave detecting element 143. The terahertz wave generating element 111 is irradiated with ultrashort pulse laser light by a femtosecond laser as pump light to generate terahertz waves, while the terahertz wave detection element 143 is irradiated with ultrashort pulse laser light as probe light to generate terahertz waves. To detect. Then, the waveform of the terahertz wave is detected by the terahertz time domain spectroscopy (THz-TDS) method using a conventionally known optical delay device. As long as the distance between the transmission / reception head 10 and the steel surface 81a can be measured by irradiating the terahertz wave, it is possible to adopt devices having various conventionally known configurations, which are not necessarily described above. It is not limited to the configuration of the device.

During operation of the surface shape evaluation device 1, terahertz waves are emitted from the transmission / reception head 10. Specifically, the terahertz wave generated in the terahertz wave generating element 111 is pulsed by the shutter 114 and emitted as a terahertz pulse wave through the hemispherical lens 112 and the collimating lens 113. Here, the terahertz wave emitted from the terahertz wave transmitting unit 11 is typically a terahertz pulse wave emitted intermittently, but may be a tone burst wave. Further, if the distance from the transmission / reception head 10 to the steel surface 81a can be measured, the terahertz wave emitted from the terahertz wave transmitting unit 11 may be a terahertz continuous wave without providing the shutter 114.

The terahertz wave emitted from the terahertz wave transmitting unit 11 passes through the beam splitter 12 and is irradiated to a predetermined position on the surface of the object 80 via the objective lens 13. Most of the terahertz waves radiated from the side of the anticorrosion layer 82 with respect to the object 80 pass through the anticorrosion layer 82 and are reflected by the steel surface 81a. The terahertz wave reflected on the surface 82a of the anticorrosion layer 82 is slight. The reflected terahertz wave is incident on the beam splitter 12 via the objective lens 13. The reflected terahertz wave is reflected by the beam splitter 12 and introduced into the terahertz wave receiving unit 14 as the terahertz wave receiving means.

The scanner 30 as a scanning means includes a uniaxial movement mechanism 31, a uniaxial movement mechanism 32, a carriage 33, and a leg portion 34. A transmission / reception head 10 is installed on the carriage 33. The scanner 30 is configured to be able to move the carriage 33 at least one-dimensionally along a predetermined uniaxial direction (x-axis direction) by driving a uniaxial moving mechanism 31 composed of, for example, a ball screw or a stepping motor. Has been done. The uniaxial movement mechanism 31 can define the coordinates (x) along the uniaxial direction.

Further, the scanner 30 carries a carriage along a direction (y-axis direction) orthogonal to a predetermined uniaxial direction, which is different from a predetermined uniaxial direction by driving the other axial moving mechanism 32. 33 is configured to be movable. As a result, the carriage 33 can be moved two-dimensionally by driving the uniaxial movement mechanism 31 and the other axial movement mechanism 32. By driving the uniaxial movement mechanism 31 and the other axial movement mechanism 32, the coordinates (x, y) along the uniaxial direction and the other axial direction can be defined, respectively.

Further, the uniaxial direction moving mechanism 31 and the other axial direction moving mechanism 32 may be configured so that at least one of them can be moved along a direction (circumferential direction) along a curve such as a circle or an ellipse. In this case, the coordinates (θ _y ) along the circumferential direction can be defined by the uniaxial movement mechanism 31 and the other axial movement mechanism 32. Similarly, coordinates (x, θ _y ) and coordinates (θ _x , y) along the uniaxial direction and the circumferential direction can be defined. In the following description, the above coordinates are collectively referred to as coordinates (x, y).

The leg portion 34 as a fixing jig is for fixing the scanner 30 to the surface of the object 80. When the scanner 30 is fixed to the object 80 by the legs 34, the coordinates (x,) of the surface of the object 80 are made substantially parallel to the surface of the object 80 by making the plane composed of the uniaxial direction and the other axial direction substantially parallel to the surface of the object 80. y) can be defined. A transmission / reception head 10 is fixed to the carriage 33 of the scanner 30. By making the carriage 33 face the object 80, the terahertz wave emitted from the transmission / reception head 10 can be applied to the object 80. By driving the scanner 30, the transmission / reception head 10 can be scanned one-dimensionally or two-dimensionally with respect to the surface 82a.

The transmission / reception head 10 is controlled by the terahertz transmission / reception controller 40. The terahertz transmission / reception controller 40 performs various controls on the transmission / reception head 10 and processes the signal detected by the transmission / reception head 10. The terahertz transmission / reception controller 40 includes a signal amplification unit 41, a bias generation unit 42, a lock-in detection unit 43, and a storage unit 44. The signal amplification unit 41 amplifies the signal detected by the terahertz wave reception unit 14, and outputs the signal as terahertz wave reception intensity data to the lock-in detection unit 43. The bias generation unit 42 generates a bias voltage to bias the terahertz wave generating element 111 and the terahertz wave detecting element 143, and changes the terahertz wave transmitted or received according to the bias voltage. The terahertz wave transmitted or received by the terahertz wave generating element 111 and the terahertz wave detecting element 143 may be weak. In this case, lock-in detection is used to detect the terahertz wave. At the time of lock-in detection, the terahertz wave transmitting unit 11 uses a modulated reference signal as the bias voltage of the terahertz wave generating element 111, so that the noise component of the terahertz wave detection signal is removed. The storage unit 44 stores the terahertz wave reception intensity data detected by the terahertz wave receiving unit 14 in association with the coordinates (x, y).

The scanner controller 60 generates drive signals for the uniaxial movement mechanism 31, the other axial movement mechanism 32, and the carriage 33 in the scanner 30. Further, the scanner controller 60 monitors the position of the terahertz wave on the surface of the object 80 as a result of the drive as well as the generation of the drive signal, and monitors the coordinates (x, y). Generate terahertz wave reflection position data including information. The terahertz wave reflection position data generated by the scanner controller 60 is associated with the terahertz wave reception intensity data by the terahertz transmission / reception controller 40. The terahertz wave reflection position data and the terahertz wave reception intensity data are each stored in the storage unit 44 and then supplied to the analysis control unit 70.

The analysis control unit 70 as a control means collectively controls the terahertz transmission / reception controller 40 and the scanner controller 60. The analysis control unit 70 has a distance measuring processing unit 71 as an analysis means. The terahertz wave reflection position data and the terahertz wave reception intensity data recorded in the storage unit 44 are supplied to the distance measuring processing unit 71 in association with each other. The distance measuring processing unit 71 derives time information (hereinafter, A scope data) from the transmitting / receiving wave head 10 to the reflection on the steel surface 81a based on the terahertz wave reflection position data including the coordinates and the terahertz wave receiving intensity data. It is configured to be possible. Further, the distance measuring processing unit 71 obtains information (hereinafter, B scope data) of the distance between the wave transmitting / receiving head 10 and the steel surface 81a in the vertical cross section (hereinafter, the distance between the head steel surfaces) based on the derived A scope data. Generate. Here, the derivation and generation of the B scope data from the A scope data by the distance measuring processing unit 71 can be performed based on, for example, a conventionally known Time Of Flight (TOF) method, but other The method may be adopted.

The analysis control unit 70 may be composed of a control unit as a control means, an analysis unit as an analysis means, and a distance measuring processing unit 71 in the present embodiment. When the analysis control unit 70 is configured as a separate body of the control unit and the analysis unit, the control unit and the analysis unit may be connected by a wired cable or the like, or may be connected via a wireless network or the like. In this case, the terahertz wave reflection position data generated by the scanner controller 60 may be stored in a predetermined recording unit (not shown) in the control unit in a state where it can be supplied to the distance measuring processing unit 71 as position information.

(Surface shape evaluation method)
Next, a surface shape evaluation method using the surface shape evaluation device 1 configured as described above will be described. Before explaining the surface shape evaluation method according to one embodiment, the problems of the prior art will be described in order to facilitate the understanding of the present invention. FIG. 2 is a schematic view for explaining a problem when the surface 82a of the anticorrosion layer 82 is inclined with respect to the steel surface 81a in the method for evaluating the surface shape. FIG. 3 is a schematic diagram for explaining a problem when the thickness distribution of the anticorrosion layer 82 is non-uniform in the surface shape evaluation method. 2 and 3 show an example in which a part of the steel surface 81a is thinned to form a thinned portion 83 in the object 80 in which the anticorrosion layer 82 is provided on the upper layer of the steel material 81. By pressing the legs 34 against the surface of the object 80, the scanner 30 provided with the wave transmitting / receiving head 10 is fixed to the object 80. Here, in order to facilitate understanding, a case where the scanner 30 is scanned one-dimensionally will be described as an example.

As shown in FIG. 2A, the scanning direction (both-direction arrows in the drawing) of the wave transmitting / receiving head 10 in the scanner 30 is substantially parallel to the surface 82a of the anticorrosion layer 82. The transmission / reception head 10 generates terahertz reception data by, for example, irradiating the steel surface 81a with a pulsed terahertz emission wave L ₁ and detecting the reflected terahertz reflection wave L ₂ . The ranging processing unit 71 of the surface shape evaluation device 1 generates A-scope data based on the time information derived from the terahertz reception data. The distance measuring processing unit 71 generates B scope data 21 indicating the distance between the head steel surfaces as shown in FIG. 2B from the A scope data. However, as shown in FIG. 2A, for example, when the thickness of the anticorrosion layer 82 increases from one side to the other, the surface 82a of the anticorrosion layer 82 is inclined with respect to the steel surface 81a, and the wave transmitting / receiving head The scanning direction of 10 is not parallel to the steel surface 81a. That is, the wave transmitting / receiving head 10 is scanned non-parallel to the steel surface 81a. In this case, the B scope data 21 generated by the distance measuring processing unit 71 has a shape inclined with respect to the virtual reference line 20 which is the scanning direction of the transmission / reception head 10. The alternate long and short dash line in FIG. 2B is a parallel line parallel to the virtual reference line 20 and intersecting one point of the B scope data 21. In this case, in the portion where the deviation δ ₁ is large, it is not possible to distinguish whether or not the increase in the distance between the wave transmitting / receiving head 10 and the steel surface 81a is caused by the wall thinning portion 83, so that the unevenness of the steel surface 81a is extracted. It becomes difficult to evaluate.

On the other hand, when the thickness of the anticorrosion layer 82 is not uniform as shown in FIG. 3A, even if the leg portion 34 is pressed against the surface 82a of the object 80 to fix the scanner 30, the wave transmitting / receiving head 10 is used. It becomes difficult to keep the distance between the object 80 and the surface 82a of the object 80 constant. Further, due to the unevenness of the anticorrosion layer 82, the scanning direction of the wave transmitting / receiving head 10 (both-direction arrows in the drawing) is not parallel to the steel surface 81a. In this state, the terahertz wave is irradiated from the transmission / reception head 10 to the steel surface 81a, the distance between the head steel surfaces is measured, and the B scope data 21 is generated. As shown in FIG. 3B, the scanner 30 is installed. The measurement is performed in a state where the unevenness of the surface 82a is superimposed on the fluctuation of the distance between the transmission / reception head 10 and the surface 82a of the object 80 due to the state. In this case, the generated B-scope data 21 is greatly inclined with respect to the virtual reference line 20. As a result, it is not possible to distinguish whether or not the increase in the distance between the head steel surfaces is caused by the wall thinning portion 83 in the portion where the deviation δ ₂ is large, so only the unevenness of the steel surface 81a is extracted and evaluated. Becomes difficult.

Therefore, as a result of diligent studies conducted by the present inventor in order to solve the above-mentioned problems, measurement is performed in a healthy portion where there is a high probability that the thinned portion 83 does not exist, and correction is performed using this healthy portion. I came up with a way to do it. That is, first, by measuring the sound portion of the steel surface 81a, a straight line or a plane along the sound portion of the steel surface 81a is set. After that, a method of appropriately performing rotation conversion correction processing on the B scope data actually obtained by the measurement is proposed so that the scanning direction of the transmission / reception head 10 and the straight line or the plane along the sound portion are parallel. I put it out. Further, when the B scope data is generated at different assumed positions, the portions corresponding to the sound parts of the steel surface 81a in the plurality of B scope data are actually measured so as to be positioned linearly or planarly with each other. We have also devised a method for appropriately performing correction processing such as translation on the obtained B scope data. The surface shape evaluation method according to the embodiment of the present invention described below is an evaluation method performed by executing the above correction processing method by the surface shape evaluation device 1.

That is, as shown in FIGS. 2A and 3A, the scanner 30 is installed on the object 80 by using the legs 34. After that, the terahertz emission wave L ₁ is irradiated from the transmission / reception head 10 of the scanner 30 to the steel surface 81a from the corrosion protection layer 82 side (irradiation step). In this state, the scanner 30 scans the transmission / reception head 10. The terahertz reflected wave L ₂ reflected by the steel surface 81a is detected by the transmission / reception wave head 10 and supplied as terahertz reception data to the analysis control unit 70 of the surface shape evaluation device 1 (reception step). After that, as shown in FIGS. 2 (b) and 3 (b), the distance measuring processing unit 71 of the analysis control unit 70 sets a line parallel to the scanning direction of the transmission / reception head 10 as the virtual reference line 20. On the other hand, the distance measuring processing unit 71 generates the B scope data 21 from the A scope data calculated based on the input terahertz reception data (B scope data generation step).

FIG. 4 is a schematic view for explaining a state in which the scanning direction of the transmission / reception head 10 is inclined with respect to the steel surface 81a. FIG. 5 is a schematic view for explaining a method of extracting a sound portion of a steel surface in an evaluation object in the surface shape evaluation method according to the present embodiment. 6 and 7 are schematic views for explaining the inclination correction method in the evaluation method according to the present embodiment.

As shown in FIG. 4A, when the scanning line 10L of the wave transmitting / receiving head 10 is non-parallel to the steel surface 81a, the B scope data corresponding to the steel surface 81a is shown in FIG. 4B. The portion 21 is inclined with respect to the virtual reference line 20.

Here, in the steel structure, which is an example of the object 80, most of the parts excluding the parts where the on-site construction is performed such as welding at the installation site are painted in a controlled and stable environment such as a factory. Anticorrosion work such as coating is performed. The portion of the steel surface 81a that has been subjected to anticorrosion under a stable environment exhibits stable anticorrosion performance and hardly corrodes. Such a portion is considered to be a sound portion on the steel surface 81a. Therefore, the distance measuring processing unit 71 selects at least two portions where the wall thinning portion 83 does not exist and the steel surface 81a is likely to be sound. The distance measuring processing unit 71 extracts from the generated B scope data 21 a portion of the steel surface 81a corresponding to a portion having a high probability of being a sound portion. In the example shown in FIG. 5, when the transmission / reception head 10 is scanned linearly like the scanning line 10L along the uniaxial direction, the distance measuring processing unit 71 obtains black circles from the generated B scope data 21. The part is extracted as sound data 211.

Next, as shown in FIG. 6, based on at least two sound data 211 extracted from the B scope data 21, a line connecting these sound data 211 by linear approximation is set as a sound measurement line 22. In other words, a linear line along the steel surface 81a assuming that all the steel surfaces 81a are sound parts is set as the sound measurement line 22. The alternate long and short dash line in FIG. 6 intersects one point of the B scope data 21 and is a line parallel to the virtual reference line 20.

The distance measuring processing unit 71 derives the distance between the virtual reference line 20 and the sound measurement line 22 as a linear function d (x) of the coordinates x in the uniaxial direction. In this case, the linear function d (x) is expressed by the following equation (1). The distance measuring processing unit 71 derives the slope a of the sound measurement line 22 from the distance d (x) between the virtual reference line 20 and the sound measurement line 22, so that the slope of the scanning line 10L (see FIG. 4A) is tilted. Derivation of θ. As shown in FIG. 6, the inclination θ of the scanning line 10L is also an angle formed by the parallel line (dashed line) of the virtual reference line 20 and the sound measurement line 22. The distance measuring processing unit 71 may directly derive the angle θ formed by the virtual reference line 20 and the sound measurement line 22 without deriving the linear function d (x).
d (x) = ax + b (a: slope of sound measurement line, b: constant) ... (1)

Next, the distance measuring processing unit 71 sets the following equations (2) and (3) to the B scope data 21 so that the sound measurement line 22 of the B scope data 21 is parallel to the virtual reference line 20. According to the equation, the inclination is corrected by performing the rotation conversion with any one point on the sound measurement line 22 as the rotation center (origin in the rotation conversion) 1. Note that z in the equations (2) and (3) is the coordinates in the height direction of the B scope data 21 with respect to the rotation center of the rotation transformation. Further, when the rotation conversion is performed on the sound measurement line 22 by using the equations (2) and (3), the origin in the rotation conversion is selected so that z ′ becomes 0 after the rotation conversion. When the distance measuring processing unit 71 performs rotation conversion processing on the B scope data 21 so that the virtual reference line 20 and the sound measurement line 22 are parallel, the B scope rotation data 21R is generated as shown in FIG. Will be done. The sound measurement line 22R is a rotation-converted line of the sound measurement line 22.
x'= xcosθ-zsinθ ... (2)
z'= xsinθ + zcosθ ... (3)

From the above, sound data 231 and wall thinning data 232 in the B scope rotation data 21R, that is, an image can be obtained. The analysis control unit 70 can evaluate the unevenness property of the steel surface 81a along the uniaxial direction from the image of the B scope rotation data 21R (evaluation step). In other words, the sound data 211 included in the generated B scope data 21 corresponding to at least two sound parts of the steel surface 81a separated from each other corresponds to the virtual reference line 20 corresponding to the scanning line 10L of the transmission / reception head 10. The B scope data 21 is corrected so that the distance is substantially equal to the above, and the B scope rotation data 21R is obtained. Based on this B scope rotation data 21R, the unevenness property of the steel surface 81a can be evaluated.

As described above, the transmitter / receiver head 10 is scanned in a predetermined uniaxial direction by the scanner 30, the distance between the head steel surfaces is measured, and the B scope rotation data 21R is generated from the B scope data 21 along the uniaxial direction. , The unevenness of the steel surface 81a can be evaluated linearly.

Further, the scanning of the wave transmitting / receiving head 10 along the uniaxial direction described above may be repeated by moving along the other axial direction using a scanner 30 capable of scanning in the biaxial direction. In this case, the transmission / reception wave head 10 intermittently and planarly irradiates the surface of the object 80 with the terahertz emission wave L ₁ and receives the terahertz reflection wave L ₂ . As a result, the B-scope rotation data 21R generated and corrected by the distance measuring processing unit 71 by scanning along the uniaxial direction is sequentially arranged in the other axial direction to make the unevenness of the steel surface 81a of the object 80 a surface. Can be evaluated as a condition.

On the other hand, the steel surface 81a is evaluated in a planar shape by using a scanner 30 capable of scanning only in the uniaxial direction, and a region wider than the scannable range of the scanner 30 capable of scanning in the biaxial direction is evaluated in a planar shape. In order to do so, it is necessary to rearrange the scanner 30 on the object 80. According to the knowledge and examination of the present inventor regarding this point, when the scanner 30 is remounted on the object 80, the distance between the head steel surfaces measured due to the unevenness of the anticorrosion layer 82 and the like occurs. The problems that cause this variation will be described below.

FIG. 8 is a schematic diagram for explaining a problem when the scanner 30 is rearranged on the object 80. 8 (a) and 8 (b) are schematic views corresponding to FIGS. 4 (a) and 4 (b), respectively. 8 (c) and 8 (d) are schematic views corresponding to FIGS. 4 (a) and 4 (b), respectively. 8 (a) and 8 (b) show the state of the scanner 30 before the replacement. 8 (c) and 8 (d) show the state of the scanner 30 after the replacement. For simplification of the description, in FIG. 8, the scanning line 10L of the wave transmitting / receiving head 10 and the portion of the steel surface 81a other than the thinned portion 83 are made substantially parallel, and the scanning line 10L is aligned in the uniaxial direction. It is straight.

As shown in FIGS. 8A and 8C, when the scanner 30 is rearranged along a direction other than the scanning line 10L along one axis direction (hereinafter, simply referred to as rearrangement), the other Due to the non-uniformity of the thickness of the anticorrosion layer 82 in the axial direction, the distance between the head steel surface of the wave transmitting / receiving head 10 and the steel surface 81a changes. In FIGS. 8 (a) and 8 (c), for example, the distance between the head steel surfaces changes from the distance D to the distance d. In this case, as shown in FIG. 8 (b) and FIG. 8 (d), the distance from the virtual reference line 20 of the resulting B-scope data 21 is changed from the distance D _B to the distance d _B. As described above, when the position of the scanner 30 changes with respect to the position on the steel surface 81a due to the refilling, the geometrical positional relationship between the scanning line 10L and the steel surface 81a changes before and after the refilling. As a result, before and after the refilling, the B scope data 21 is displaced in the height direction, that is, in the vertical direction due to the change in the distance from the virtual reference line 20.

That is, the B scope data 21a obtained before the refilling shown in FIG. 8 (b) and the B scope data 21b obtained after refilling along the other axis direction shown in FIG. 8 (d) are filled. The data has a discontinuous step in the height direction along the other axis direction before and after the replacement. This becomes particularly remarkable when the scanner 30 is continuously refilled to evaluate the steel surface 81a. Even in this case, for the same reason as in the case where the scanning line 10L is inclined with respect to the steel surface 81a, it is not possible to distinguish between the sound portion and the thinned portion in the B scope data 21, and the unevenness property of the steel surface 81a. It becomes difficult to evaluate. Therefore, the present inventor has made a diligent study and came up with the idea of correcting the positional deviation when the positional deviation occurs in the height direction of the plurality of B scope data 21a and 21b.

9 and 10 are schematic views for explaining a method of correcting the vertical direction with respect to the measurement surface in the evaluation method according to the present embodiment. FIG. 9 shows the B scope rotation data 21Ra and 21Rb obtained by the rotation conversion process by the distance measuring processing unit 71 described above. The B scope rotation data 21Ra is the B scope data 21a obtained by scanning the transmission / reception head 10 in the uniaxial direction as the first scan, and is rotationally converted so that the sound measurement line 22a is parallel to the virtual reference line 20. This is the obtained data. Both the B scope data 21a and the B scope rotation data 21Ra can correspond to the first B scope data. The B-scope rotation data 21Rb is obtained by scanning the transmission / reception head 10 in the uniaxial direction as the second scan after the scanner 30 is rearranged along the other axis direction, and the sound measurement line 22b provides the B-scope rotation data 21Rb. This is data obtained by rotational conversion so as to be parallel to the virtual reference line 20. Both the B scope data 21b and the B scope rotation data 21Rb can correspond to the second B scope data.

The distance measuring processing unit 71 matches the virtual reference lines 20 of the B scope rotation data 21Ra and 21Rb, and compares the B scope rotation data 21Ra and 21Rb with each other. In the example shown in FIG. 9, the B scope rotation data 21Ra and 21Rb are in a state where the virtual reference lines 20 coincide with each other, and are deviated by a distance Δ along the height direction (z-axis direction). On the other hand, the distance measuring processing unit 71 calculates the height correction amount in the height direction of the B scope rotation data 21Ra and 21Rb so that the sound measurement lines 22a and 22b coincide with each other in the height direction. In other words. The distance measuring processing unit 71 calculates the z-axis correction amount so that the z-coordinates of the sound measurement lines 22a and 22b match. The distance measuring processing unit 71 performs translation conversion to move the B scope rotation data 21Ra and 21Rb in the height direction based on the calculated height correction amount.

After matching the z-coordinates of the sound measurement lines 22a and 22b by the above translation transformation, the distance measuring processing unit 71 transfers the B scope rotation data 21Ra and 21Rb in the other axis direction, for example, as shown in FIG. Place it at the measured position along the y-axis direction. Further, the distance measuring processing unit 71 sets the virtual reference plane 20P by making the above-mentioned virtual reference line 20 continuous along the other axis direction. As a result, in the B scope rotation data 21Ra and 21Rb obtained along the uniaxial direction, the sound data 211a and 211b, which are the portions corresponding to the sound portion of the steel surface 81a, are arranged on the same surface. Therefore, the wall thinning data 212a and 212b, which are the portions corresponding to the wall thinning portion 83 of the steel surface 81a, can be accurately extracted by images and data, and the wall thinning depth can be quantified. Therefore, the unevenness property generated on the steel surface 81a can be accurately evaluated.

According to the above-described embodiment, the steel material 81 provided with the anticorrosion layer 82 is irradiated with the terahertz emission wave L ₁ from the transmission / reception head 10 from the anticorrosion layer 82 side while determining the measurement position. The surface of the object 80 is scanned for each coordinate to evaluate the unevenness of the steel surface 81a. In this case, the transmission / reception head 10 is scanned along the uniaxial direction (for example, the x-axis direction) to generate the B scope data 21, and the soundness of the B scope data 21 corresponding to the sound portion of the steel surface 81a by rotation conversion is performed. By correcting the generated B scope data so that the data 211 is horizontal to the virtual reference line 20 corresponding to the scanning line 10L, the unevenness of the steel surface 81a of the object 80 is evaluated linearly. Can be done. Further, by moving the wave transmitting / receiving head 10 in the other axial direction (for example, the y-axis direction) and further scanning in the uniaxial direction, the unevenness of the steel surface 81a can be evaluated in a planar manner.

Further, a plurality of B scope data 21a and 21b are generated by rearranging the scanner 30, rotation conversion is performed so that the sound measurement lines 22a and 22b are parallel to the scanning line 10L, respectively, and further, sound measurement lines 22a and 22b are performed. Make corrections in the height direction (vertical direction) so that they are at the same height as each other. As a result, information on the unevenness of the steel surface 81a can be collected from the information obtained by the wave transmitting / receiving head 10 at the respective coordinates (x, y), and the surface shape of the steel surface 81a can be evaluated in a planar manner.

Although one embodiment of the present invention has been specifically described above, the present invention is not limited to the above-mentioned one embodiment, and various modifications based on the technical idea of the present invention are possible. For example, the configuration of the terahertz wave transmitter / receiver given in the above-described embodiment is merely an example, and an apparatus having a different configuration may be used if necessary. Further, the present invention is not limited by the description and drawings which form a part of the disclosure of the present invention according to the above-described embodiment.

(Surface shape evaluation system)
For example, in the above-described embodiment, the surface shape evaluation device 1 has been described, but the configuration is not necessarily limited to all of them. That is, the transmission / reception head 10, the scanner 30, the terahertz transmission / reception controller 40, and the scanner controller 60 can be integrated into a terahertz wave measuring instrument. In this case, the analysis control unit 70 may be composed of a personal computer or the like. When the terahertz wave measuring instrument and the analysis control unit 70 are separated, the terahertz wave measuring instrument and the analysis control unit 70 are configured to be capable of transmitting and receiving data via various networks such as LAN communication or the Internet. Is possible. That is, the terahertz wave reception intensity data on the surface of the object 80 is acquired by the terahertz wave measuring instrument while being associated with the coordinates (x, y) (terahertz wave reflection position data) of the surface of the object 80, and is acquired via the network. It may be configured to be supplied to a separate analysis control unit 70. In this case, the surface shape evaluation system is configured by the terahertz wave measuring instrument as the terahertz wave measuring means and the analysis control unit 70.

Further, the transmission / reception head 10 and the scanner 30 may be integrated into a terahertz wave measurement head, and may be configured separately from the terahertz transmission / reception controller 40, the scanner controller 60, and the analysis control unit 70. Further, all of them may be configured separately so that data, signals and the like can be transmitted and received to each other via various networks.

In the above-described embodiment, the distance between the head steel surface of the wave transmitting / receiving head 10 and the steel surface 81a is derived based on the TOF method, but it may be performed based on another method. For example, when the terahertz wave emitted from the transmission / reception head 10 is a terahertz continuous wave, the terahertz wave is obliquely irradiated from the terahertz wave transmitter 11 of the transmission / reception head 10 to the surface of the object 80 to obtain the terahertz wave. The receiving unit 14 may be arranged at a position of normal reflection, and the distance between the head steel surfaces may be derived based on the intensity of the detected terahertz wave reflected wave or the like.

In the above-described embodiment, the distance measuring processing unit 71 performs translational transformation on the B-scope data and then translational transformation, but performs translational transformation on the B-scope data and B-scope. Rotation conversion may be performed after the movement data is generated.

Further, in the above-described embodiment, the case where the transmission / reception head 10 is one-dimensionally scanned along the uniaxial direction has been described as an example, but the two-dimensional directions in the uniaxial direction and the other axial direction described above are two-dimensionally planarized. It may be a scanning scanner. In this case, as shown in FIG. 11, for example, provided with a leg portion 34 of the scanner 30, for example, in four positions, pairs thinning unit at position P _1, the legs 34 are objects 80 provided on P ₂ corner 83 It is preferable to install the scanner 30 so as to be in a position where there is a high probability that As a result, since the measurement range of the steel surface 81a exceeds the measurable range of the scanner 30, the steel surface 81a can be evaluated more accurately even when the scanner 30 is replaced.

Further, in the above-described embodiment, the B scope data 21 is subjected to rotation conversion so that the distances from the transmission / reception head 10 are substantially equal to each other at at least two sound parts. Although the data 21 is corrected to evaluate the unevenness property of the steel surface 81a, the correction other than the rotation conversion may be performed.

In the above-described embodiment, two B-scope rotation data 21Ra and 21Rb have been described as an example, but correction is performed for three or more B-scope rotation data in the same manner as in the two cases. That is, the reference B-scope rotation data is selected from the three or more B-scope rotation data, the height correction amount of the other B-scope rotation data is calculated, and the translation is performed. Further, for each of the three or more B-scope rotation data, the height correction amount with respect to the reference height is calculated, and the sound measurement lines in all the B-scope rotation data have the same height (z coordinate). The parallel movement conversion may be performed as follows.

1 Surface shape evaluation device 10 Transmission / reception head 10L Scan line 11 Terahertz wave transmitter 14 Terahertz wave receiver 20 Virtual reference line 20P Virtual reference planes 21,21a, 21b B Scope data 21R, 21Ra, 21Rb B Scope rotation data 22, 22R , 22a, 22b Sound measurement line 30 Scanner 31 Uniaxial movement mechanism 32 Other axial movement mechanism 33 Carriage 34 Leg 40 Terahertz transmission / reception controller 60 Terahertz wave transmission / reception controller 60 Scanner controller 70 Analysis control unit 71 Distance measurement processing unit 80 Object 81 Steel 81a Steel surface 82 Anticorrosion layer 83 Thinned parts 211, 211a, 211b, 231 Healthy data 212a, 212b, 232 Thinning data L ₁ Terahertz emission wave L ₂ Terahertz reflected wave

Claims (4)

A terahertz wave transmitting unit capable of irradiating a terahertz wave at a predetermined position on the surface of an object provided with a non-metal layer on the upper layer of the metal substrate and scanning the surface of the object, and the object. A terahertz wave measuring means configured to be able to receive a terahertz wave reflected at a predetermined position and having a terahertz wave receiving unit capable of scanning while associating the surface of the object with coordinates.
The distance between the terahertz wave measuring means and the surface of the metal substrate can be derived based on the received data of the terahertz wave received by the terahertz wave receiving unit in the portion where the surface of the object is scanned. B-scope data on the surface of the metal substrate is generated based on the distance, and the portions corresponding to at least two healthy portions on the surface of the metal substrate included in the generated B-scope data are described above. It is characterized by including an analysis means for correcting the B scope data and evaluating the unevenness of the surface of the metal substrate so that the distance is substantially equal to the virtual reference line corresponding to the scanning line of the terahertz wave measuring means. Surface shape evaluation device. The analysis means
After moving the first B scope data obtained by the first scanning for executing scanning by the terahertz wave measuring means in the uniaxial direction and the terahertz wave measuring means along the other axial direction non-parallel to the uniaxial direction. , The terahertz wave measuring means of the sound part in the first B scope data with respect to the second B scope data obtained by the second scanning which executes the scanning by the terahertz wave measuring means substantially parallel to the uniaxial direction. A claim characterized in that the first B scope data and the second B scope data are corrected so that the distance between the two B scope data and the terahertz wave measuring means of the sound portion in the second B scope data becomes equal to each other. Item 2. The surface shape evaluation device according to Item 1. A terahertz wave transmitting unit capable of irradiating a terahertz wave at a predetermined position on the surface of an object provided with a non-metal layer on the upper layer of the metal substrate and scanning the surface of the object, and the object. A terahertz wave measuring means configured to be able to receive a terahertz wave reflected at a predetermined position and having a terahertz wave receiving unit capable of scanning while associating the surface of the object with coordinates.
The distance between the terahertz wave measuring means and the surface of the metal substrate can be derived based on the received data of the terahertz wave received by the terahertz wave receiving unit in the portion where the surface of the object is scanned. B-scope data on the surface of the metal substrate is generated based on the distance, and the portions corresponding to at least two healthy portions on the surface of the metal substrate included in the generated B-scope data are described above. An analysis means that corrects the B scope data and evaluates the unevenness of the surface of the metal substrate so that the distance is substantially equal to the virtual reference line corresponding to the scanning line of the terahertz wave measuring means.
A surface shape evaluation system characterized in that the received data can be transmitted and received via a network. An irradiation step in which a terahertz wave measuring means scans the surface of an object provided with a non-metal layer on the upper layer of a metal substrate and irradiates a terahertz wave at a predetermined position.
A reception step received by the terahertz wave measuring means while associating the terahertz wave reflected at the predetermined position on the object with the coordinates of the surface of the object.
Based on the received data of the terahertz wave received by the terahertz wave measuring means in the portion where the surface of the object is scanned, the distance between the terahertz wave measuring means and the surface of the metal substrate is derived, and the derived distance is derived. A B-scope data generation step for generating B-scope data on the surface of the metal substrate based on
Each of the portions corresponding to at least two sound portions on the surface of the metal substrate included in the B scope data generated in the B scope data generation step are virtual corresponding to the scanning line of the terahertz wave measuring means. A surface shape evaluation method comprising an evaluation step of correcting the B scope data so as to have a distance substantially equal to the reference line and evaluating the unevenness of the surface of the metal substrate.

Images