JP2022083881A - Layer thickness measurement method - Google Patents

Abstract

To measure the layer thickness of each layer of a laminate with good accuracy.SOLUTION: A layer thickness measurement device captures a transmission image of a laminate of a high-pressure tank, using an X-ray, acquires a scattering intensity distribution image of the laminate, sets the regression equation of scattering intensity of a helical layer in the scattering intensity distribution image, finds a difference in the scattering intensity of the regression equation from the scattering intensity distribution image, and generates the distribution of scattering intensity for layer thickness analysis (steps 100-104). Thereafter, a threshold is set from the difference between the scattering intensity of a hoop layer and the scattering intensity of a helical layer in the distribution of scattering intensity, a boundary surface between the helical and the hoop layers is extracted from the distribution of scattering intensity based on the threshold, and the layer thickness of each layer is calculated from the position of the extracted boundary surface (steps 106-110). Thus, it is possible to measure the layer thickness of each layer of the laminate with good accuracy.SELECTED DRAWING: Figure 3

Description

The present invention relates to a method for measuring the layer thickness of a laminated body.

Patent Document 1 discloses a method for evaluating the fiber orientation direction and contour of an anisotropic fiber sheet. In the disclosure of Patent Document 1, the reflected light of the light applied to the surface of the anisotropic fiber sheet is imaged, and the fiber orientation direction of the anisotropic fiber sheet is determined from the locus of movement of the bright portion on the photographed image. The contour of the anisotropic fiber sheet is detected by detecting the discontinuous portion of the portion.

On the other hand, as a non-destructive inspection for a measurement target, there is a phase contrast imaging method using X-rays. In the phase contrast imaging method, the phase difference or minute scattering generated by refraction of the light applied to the measurement target while transmitting the substance is measured and contrast is added.

JP-A-2007-187545

By the way, a high-pressure tank filled with high-pressure hydrogen gas is used for a fuel cell vehicle, a fiber-reinforced resin is used for the high-pressure tank, and the fiber bundle is substantially parallel to the tank shaft, and the end portion in the tank axial direction. The layer (helical layer) wound up to the tank dome part and the layer (hoop layer) in which the fiber bundle is wound around the tank body in the substantially circumferential direction of the tank body are alternately laminated to form a laminated body. It is formed. In such a laminated body of a high-pressure tank, since X-rays pass through the fiber reinforced resin forming the laminated body, non-contact inspection (non-destructive inspection) using a phase contrast imaging method using X-rays is possible. It has become.

On the other hand, the fibers (fiber bundles) of the hoop layer laminated in the high-pressure tank are concentrically curved and oriented with respect to the center of the high-pressure tank. However, in the phase contrast imaging method, for example, when measuring minute scattering generated in X-rays, the sensitivity to scattering generated when the orientation direction of fibers (fiber bundles) and the incident direction of X-rays coincide with each other is particularly high. have. Therefore, when X-rays are incident on the high-pressure tank from the outside in the radial direction, the scattering from the fiber bundle whose orientation direction coincides with the incident direction of the X-rays is characteristically captured, and the resulting X is captured. In the line scattering intensity distribution image, the hoop layer is emphasized more than the helical layer. At this time, in the X-ray scattering intensity distribution image, scattering due to a fiber bundle curved so that the orientation direction deviates from the incident direction of the X-ray is also captured, so that the boundary between the hoop layer and the helical layer is blurred. It is measured. Therefore, there is room for improvement in order to accurately measure the layer thickness of each layer by applying the phase contrast imaging method.

The present invention has been made in view of the above facts, and an object of the present invention is to provide a layer thickness measuring method capable of accurately measuring the layer thickness of each layer in a laminated body in which a fiber reinforced resin is laminated.

The layer thickness measuring method of the present invention for achieving the above object comprises a laminated body in which a fiber-reinforced resin is used and the first layer and the second layer are alternately laminated so that the feature amount with respect to X-rays is different. By targeting a high-pressure tank as an analysis target and receiving X-rays transmitted through the laminate by irradiating the laminate so that the feature amount differs between the first layer and the second layer by an imaging means. , An X-ray transmission image including the distribution of the feature amount is imaged for the laminate, and the distribution of the feature amount of X-ray along the layer thickness direction for the laminate is obtained from the transmission image, and the first. The regression equation of the feature amount for either the layer or the second layer is obtained, the feature amount of the regression equation is different from the transmission image, and the feature amount of the first layer and the first layer after the difference are obtained. The boundary position between the first layer and the second layer is determined from the distribution of the feature amount obtained by subtracting the feature amount of the regression equation from the transmission image based on the reference value set according to the difference from the feature amount of the two layers. It includes extracting and calculating the layer thickness of each of the first layer and the second layer from each of the extracted boundary positions.

In the layer thickness measuring method of the present invention, a phase contrast imaging method using X-rays is applied. In the layer thickness measuring method of the present invention, a fiber-reinforced resin is used, and a high-pressure tank having a laminated body in which the first layer and the second layer are alternately laminated so that the feature amount with respect to X-rays is different is targeted for measurement. The X-rays transmitted through the laminated body are imaged by irradiating the laminated body so that the feature amount differs between the first layer and the second layer by the imaging means. As a result, a transmission image including X-ray scattering information is imaged for the laminated body, and the captured transmission image includes the distribution of the feature amount as the scattering information.

Next, the distribution of the X-ray feature amount along the layer thickness direction of the laminated body was obtained from the captured transmission image, and the regression equation of the feature amount for either the first layer or the second layer was obtained. The feature amount of the regression equation is differentiated from the feature amount of the transmission image, and the reference value is set according to the difference between the feature amount of the first layer and the feature amount of the second layer after the difference. After that, the boundary position between the first layer and the second layer is extracted from the distribution of the feature amount in the transmission image based on the reference value. As a result, the boundary position between the first layer and the second layer can be accurately extracted. Further, the layer thickness of each layer can be calculated accurately by calculating the layer thickness of each of the first layer and the second layer from each of the extracted boundary positions.

As described above, according to the present invention, the boundary position between the first layer and the second layer can be accurately extracted by the phase contrast imaging method, and the thickness of each of the first layer and the second layer can be accurately extracted. The effect of being able to measure is obtained.

It is a block diagram which shows the schematic structure of the main part of the layer thickness measuring apparatus which concerns on this embodiment. (A) is a cross-sectional view in a radial direction showing a main part of a measurement target, and (B) is an enlarged cross-sectional view of the main part of (A). It is a flow chart which shows the outline of the layer thickness measurement process which concerns on this embodiment. (A) is a schematic diagram showing a distribution image of the X-ray scattering intensity in the main part of the laminated body, (B) is a schematic diagram showing an outline of the distribution of the X-ray scattering intensity in (A), and (C) is a diagram. , A schematic diagram showing a distribution image of the scattering intensity of X-rays converted using a threshold, (D) is a diagram showing an outline of the distribution of the scattering intensity in (C). (A) is a schematic diagram showing a distribution image of the scattering intensity of X-rays generated in the boundary extraction unit, (B) is a diagram showing a boundary surface, and (C) is a measured layer thickness of the hoop layer. It is a diagram which shows.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
The present embodiment includes the following aspects.
<1> A high-pressure tank in which a fiber-reinforced resin is used and a laminated body in which the first layer and the second layer are alternately laminated so that the feature amount with respect to X-rays is different is targeted for analysis, and the first layer and the above are described. By irradiating the laminate so that the feature amount differs from that of the second layer and receiving X-rays transmitted through the laminate by the imaging means, X including the distribution of the feature amount for the laminate. A transmission image of the line is imaged, and the distribution of the feature amount of the X-ray along the layer thickness direction is acquired from the transmission image for the laminated body, and the distribution of the first layer and the second layer is obtained. The feature amount of the feature amount was obtained, the feature amount of the regression equation was differentiated from the transmission image, and the feature amount was set according to the difference between the feature amount of the first layer and the feature amount of the second layer after the difference. The boundary position between the first layer and the second layer is extracted from the distribution of the feature amount obtained by subtracting the feature amount of the regression equation from the transmission image based on the reference value, and the first layer is extracted from each of the extracted boundary positions. A method for measuring the layer thickness of a laminated body, which comprises calculating the layer thickness of each of the first layer and the second layer.

<2> The regression equation is a layer thickness measurement of <1>, which is set based on the feature amount in the layer in which the change in the feature amount in the transmission image is gradual among the first layer and the second layer. Method.
<3> The feature amount is a distribution of luminance appearing in the transmission image due to the difference in the orientation direction of the fibers in the fiber reinforced resin with respect to X-rays between the first layer and the second layer. <1> Or the layer thickness measuring method of <2>.

<4> A high-pressure tank in which a fiber-reinforced resin is used and a laminated body in which the first layer and the second layer are alternately laminated so that the feature amount with respect to X-rays is different is targeted for analysis, and the first layer and the above are analyzed. An image of X-ray transmission including the distribution of the feature amount for the laminate by receiving X-rays transmitted through the laminate by irradiating the laminate so that the feature amount differs from that of the second layer. One of the first layer and the second layer, an image pickup means for imaging the image, an acquisition means for acquiring the distribution of the feature amount of X-rays along the layer thickness direction for the laminate from the transmission image, and the acquisition means. The feature amount of the regression equation is obtained from the transmission image, the feature amount of the regression equation is differentiated from the transmission image, and the difference between the feature amount of the first layer and the feature amount of the second layer after the difference is obtained. An extraction means for extracting the boundary position between the first layer and the second layer from the distribution of the feature amount obtained by subtracting the feature amount of the regression equation from the transmission image based on the set reference value, and the extracted boundary position. A layer thickness measuring device including a calculation means for calculating the layer thickness of each of the first layer and the second layer from each of the above.

<5> The regression equation is a layer thickness measurement of <4>, which is set based on the feature amount in the layer in which the change in the feature amount in the transmission image is gradual among the first layer and the second layer. Device.
<6> The luminance distribution that appears in the transmission image is applied to the feature amount because the orientation direction of the fibers in the fiber reinforced resin with respect to X-rays differs between the first layer and the second layer. 4> or <5> layer thickness measuring device.
Further, the embodiment of the present embodiment includes a layer thickness measurement program executed by a computer.

In the layer thickness measuring apparatus 10 according to the present embodiment, an X-ray transmission image acquired by the X-ray phase contrast imaging method is used. FIG. 1 shows a schematic configuration of a main part of the layer thickness measuring device 10 according to the present embodiment in a block diagram, and FIGS. 2 (A) and 2 (B) show the layer thickness measuring device 10 The main part of the layer thickness to be measured using the above is shown in the cross-sectional view in the radial direction. Note that FIG. 2B shows an enlarged outline of the main part of FIG. 2A.

As shown in FIGS. 1, 2 (A) and 2 (B), in the present embodiment, the high pressure tank 12 is applied as the measurement target of the layer thickness measuring device 10. The high-pressure tank 12 is used, for example, as a hydrogen tank (high-pressure hydrogen tank) filled with hydrogen gas as a fuel in a fuel cell vehicle or the like.

The high-pressure tank 12 includes a laminated body 14 having a substantially cylindrical outer shape (with a substantially cylindrical cross section in the radial direction) forming the tank body. In the laminated body 14, the hoop layer 16 as one of the first layer and the second layer and the helical layer 18 as the other of the first layer and the second layer are alternately formed. As an example, the laminated body 14 has a helical layer 18A, a hoop layer 16A, a helical layer 18B, a hoop layer 16B, and a helical layer 18C laminated in this order from the inside in the radial direction. As for the layer thickness which is the thickness along the radial direction of each layer of the laminated body 14, as an example, the inner helical layer 18A is formed to be thicker than the helical layers 18B and 18C and the hoop layers 16A and 16B. .. Further, in the high pressure tank 12, a liner layer 20 made of resin for preventing the permeation of hydrogen gas is formed inside the helical layer 18A in the radial direction.

The layer thickness measuring device 10 measures, for example, the layer thicknesses of the hoop layers 16 (16A, 16B) and the helical layers 18 (18A to 18C) forming the laminated body 14 in the axial middle portion of the high pressure tank 12. .. At this time, the layer thickness measuring device 10 calculates the layer thickness of each layer by extracting the boundary surface (interface) B between two adjacent layers. That is, in the layer thickness measuring device 10, the boundary surface Ba between the helical layer 18A and the hoop layer 16A, the boundary surface Bb between the hoop layer 16A and the helical layer 18B, the boundary surface Bc between the helical layer 18B and the hoop layer 16B, and the hoop. Each of the boundary surface Bd between the layer 16B and the helical layer 18C is extracted.

The radial direction of the high-pressure tank 12 is the layer thickness direction of each layer of the laminated body 14. Further, the measurement target is not limited to hydrogen gas for fuel cells, but the first layer and the second layer are alternately laminated to obtain the required cross-sectional shape, such as various high-pressure tanks used for filling high-pressure gas. High pressure tank can be applied. Further, the measurement target is not limited to the high-pressure tank, and various laminated bodies in which the first layer and the second layer are alternately laminated can be applied.

A carbon fiber reinforced resin (CFRP: Carbon Fiber Reinforced Plastic) as a fiber reinforced resin (FRP: Fiber Reinforced Plastic) is used for each of the laminate 14 (hoop layer 16 and helical layer 18). In the carbon fiber reinforced resin (similar to the fiber reinforced resin), a plurality of fibers (carbon fibers, not shown) are arranged in one direction (orientation direction of fiber bundles).

Generally, in a carbon fiber reinforced resin (the same applies to a fiber reinforced resin), when X-rays are irradiated, the irradiated X-rays are transmitted. In carbon fiber reinforced resin, transmitted X-rays are scattered by the fiber bundles. The intensity of X-ray scattering in the carbon fiber reinforced resin differs depending on the angle of the orientation direction of the fiber (carbon fiber) bundle with respect to the optical axis (incident direction) of the X-ray.

The laminate 14 is formed by winding a carbon fiber reinforced resin around the tank dome portion at the axial end of the high pressure tank 12 so that the orientation direction of the fiber bundle is substantially parallel to the axial direction of the high pressure tank 12 as the first direction. The orientation direction of the helical layer 18 and the fiber bundle was different from that of the first direction, and the carbon fiber reinforced resin was wound around the tank body in a substantially annular shape so that the fiber bundle was substantially along the circumference of the tank. It contains a hoop layer 16. Therefore, in the laminated body 14, the hoop layer 16 and the helical layer 18 are arranged so that the orientation directions of the fiber bundles are different in the radial direction.

As a result, in the laminated body 14, the X-rays scattered in the hoop layer 16 are more scattered than the X-rays scattered in the helical layer 18 with respect to the X-rays irradiated from the radial outside of the high-pressure tank 12 along the tangential direction of the predetermined portion. Is getting stronger. In such a laminate 14, for example, a helical layer 18 formed in a cylindrical shape with the orientation direction of the fiber bundles substantially axially oriented by a sheet-shaped carbon fiber reinforced resin, and a fiber bundle made of a sheet-shaped fiber reinforced resin. Can be formed by alternately laminating hoop layers 16 formed in a cylindrical shape with the orientation direction of the hoops being substantially circumferential.

In the layer thickness measuring device 10, optical characteristic values that change according to the intensity of scattering with respect to X-rays are applied as feature quantities of the hoop layer 16 and the helical layer 18 with respect to X-rays. As an example of the feature amount, the intensity of X-rays (X-ray brightness, hereinafter referred to as scattering intensity) that changes according to scattering is applied.

As shown in FIG. 1, in the layer thickness measurement process using the layer thickness measuring device 10, the phase contrast imaging device 22 to which the phase contrast imaging method using X-rays is applied is used. The phase contrast imaging device 22 is provided with a mechanism for capturing minute scattering from fibers (fiber bundles), and the phase contrast imaging device 22 is, for example, a Talbot low interferometer for realizing phase contrast imaging, an X-ray source (X-ray source). Both are provided with a detector (not shown) and a detector (detector) 24 as an image pickup means.

The phase contrast imaging device 22 irradiates the laminated body 14 of the high-pressure tank 12 with X-rays while rotating the high-pressure tank 12 around the central axis of the high-pressure tank 12 (may be relative rotation), and a plurality of circumferential positions. By imaging the transmitted image of the X-rays in the above by the detector 24, the transmitted image including the scattering information of the X-rays in the laminated body 14 is acquired. Further, in the phase contrast imaging device 22, predetermined image processing and arithmetic processing are performed on the transmission image captured by the detector 24 in an arithmetic processing unit (not shown), and a plurality of positions in the circumferential direction of the laminated body 14 of the high pressure tank 12 are performed. A transmission image for each of P is generated and output.

The detector 24 of the phase contrast imaging device 22 is electrically connected to the layer thickness measuring device 10. The layer thickness measuring device 10 includes an image pickup unit 26 constituting an image pickup means, a feature amount acquisition unit 28 as a feature amount acquisition means, a boundary extraction unit 30 as a boundary extraction means, and a layer thickness calculation unit 32 as a layer thickness calculation means. And an output unit 34 is provided.

The layer thickness measuring device 10 has a configuration of a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a storage, a communication interface, a display unit, and an operation unit, and each configuration is via a bus. It is equipped with microcomputers (not shown) that are connected to each other so that they can communicate with each other.

The ROM stores various programs and various data. RAM temporarily stores programs and data as a work area. The storage is composed of an HDD (Hard Disk Drive), an SSD (Solid State Drive), or the like, and stores various programs including an operating system and various data. The communication interface is an interface for communicating with other devices such as a server and a printing machine, and for example, standards such as Ethernet (registered trademark), FDDI, and Wi-Fi (registered trademark) are used. The operation unit includes a pointing device such as a mouse and a keyboard, and is used for performing various inputs. Further, the display unit is, for example, a liquid crystal display, and displays various information. The display unit may adopt a touch panel method and function as an operation unit.

In the layer thickness measuring device 10, a layer thickness measuring program for measuring the layer thickness is stored in the ROM or the storage, and the CPU reads the layer thickness measuring program from the ROM or the storage and executes the RAM as a work area. Functions according to the layer thickness measurement program are realized. As a result, in the layer thickness measuring device 10, each function of the image pickup unit 26, the feature amount acquisition unit 28, the boundary extraction unit 30, and the layer thickness calculation unit 32 is realized. Further, in the layer thickness measuring device 10, the function of the output unit 34 is realized by the display unit or the like. The function of the output unit 34 may be realized by an output function using a communication interface or the like.

The image pickup unit 26 of the layer thickness measuring device 10 uses the phase contrast imaging device 22 to image the laminated body 14 of the high pressure tank 12, and each of the plurality of positions P in the circumferential direction from the phase contrast imaging device 22 to the high pressure tank 12. Acquires a transmission image including X-ray scattering information of the laminated body 14 in the above. Further, the image pickup unit 26 performs a predetermined (known) image processing on the transmission image including the X-ray scattering information in the laminated body 14 of the high-pressure tank 12, so that the distribution image (image) of the X-ray scattering intensity is performed. Convert to data) and output.

The feature amount acquisition unit 28 distributes the scattering intensity of X-rays for each pixel along the layer thickness direction of the laminated body 14 from the distribution image of the scattering intensity of X-rays output from the imaging unit 26 (X-rays caused by scattering). Generate data (profile) indicating the intensity part). The X-ray scattering intensity distribution image obtained from the transmitted image includes the X-ray scattering intensity distribution in the hoop layer 16 and the X-ray scattering intensity in the helical layer 18 which is lower than the X-ray scattering intensity distribution in the hoop layer 16. Distribution is included. From here, the feature amount acquisition unit 28 obtains a regression equation that approximates the scattering intensity of X-rays in the hoop layer 16 or the helical layer 18, and the scattering intensity obtained by subtracting the scattering intensity of the regression equation from the X-ray scattering intensity distribution image. Acquire the distribution (distribution image). Further, the feature amount acquisition unit 28 sets a threshold value as a reference value according to the scattering intensity of the hoop layer 16 and the scattering intensity of the helical layer 18 in the distributed scattering intensity distribution, and the scattering intensity obtained by the difference is set. Generates data (scattering intensity profile) showing the distribution of scattering intensity based on the threshold (for example, exceeding the threshold) in the distribution.

Further, the boundary extraction unit 30 extracts the boundary position of each layer from the scattering intensity profile based on the threshold value, and specifies the position coordinates of the boundary position. As the position coordinates for each boundary, coordinates or the like with reference to a predetermined position in the radial direction of the laminated body 14 (high pressure tank 12) (for example, the origin O which is the center position of the high pressure tank 12) can be applied. The boundary extraction unit 30 includes a boundary surface between the helical layer 18A and the hoop layer 16A, a boundary surface between the hoop layer 16A and the helical layer 18B, a boundary surface between the helical layer 18B and the hoop layer 16B, and a hoop layer 16B and the helical layer 18C. The position coordinates of each of the boundary surfaces with and are extracted.

The layer thickness calculation unit 32 calculates the layer thicknesses of the hoop layers 16A and 16B and the helical layer 18B from the position coordinates of each of these boundary surfaces. Further, in the layer thickness calculation unit 32, since the position coordinates of the boundary surface of the helical layer 18A with the liner layer 20 are specified, the layer thickness of the helical layer 18A can be calculated, and the position coordinates of the outer peripheral surface of the helical layer 18C can be calculated. Is specified, the layer thickness of the helical layer 18C can be calculated. The output unit 34 outputs the calculated layer thickness of each layer.

Hereinafter, as the operation of the present embodiment, the layer thickness measurement process of the laminated body 14 in the high pressure tank 12 to be measured using the layer thickness measuring device 10 will be described with reference to the drawings. FIG. 3 shows an outline of the layer thickness measurement process in the layer thickness measuring device 10 in a flow chart.

In the first step 100 of FIG. 3, in the layer thickness measuring device 10, the image pickup unit 26 performs the image pickup process of the laminated body 14. In the imaging process, the X-rays transmitted through the measurement site of the laminated body 14 of the high-pressure tank 12 are received by the detector 24 in the phase contrast imaging device 22, and are acquired as a transmission image including the scattering information at the measurement site to perform predetermined image processing. The scattering intensity distribution image of the X-ray in which the above is performed is output. The image pickup unit 26 acquires the scattering intensity image of this X-ray.

In the next step 102, in the layer thickness measuring device 10, the feature amount acquisition unit 28 sets the regression equation f (y) in the X-ray scattering intensity distribution image. The feature amount acquisition unit 28 sets a regression equation f (y) that approximates the scattering intensity of X-rays in the helical layer 18. Further, the feature amount acquisition unit 28 generates a scattering intensity distribution (feature amount distribution) obtained by subtracting the scattering intensity of the regression equation f (y) from the X-ray scattering intensity distribution image in step 104, and scatters in step 106. The threshold Is is set from the intensity distribution.

FIG. 4 (A) shows an example of an X-ray intensity distribution image (scattering intensity distribution image) in a schematic diagram, and FIG. 4 (B) shows the scattering intensity distribution image of FIG. 4 (A). The outline of the X-ray scattering intensity distribution at the position Pa in the axial direction (tank axial direction) of the high-pressure tank 12 is shown in the diagram. Further, FIG. 4C shows a schematic diagram of an example of a distribution image (transmission image) of the scattering intensity I converted with reference to the threshold Isth, and FIG. 4D shows FIG. 4 (B) Scattering intensity distribution The outline of the distribution of the scattering intensity I of X-rays at the position Pa of the image is shown in the diagram. In the drawings, the radial direction of the high-pressure tank 12 is the Y-axis direction, and the axial direction of the high-pressure tank 12 is the X-axis direction. Further, in FIGS. 4 (B) and 4 (D), the position (position coordinates) in the X-axis direction is shown by the number of pixels.

As shown in FIG. 4A, in the X-ray transmission image (scattering intensity distribution image) obtained by the phase contrast imaging apparatus 22, the brightness (scattering) in the hoop layer 16 having a large X-ray scattering intensity (strong scattering). Strength) increases. Further, in the X-ray scattering intensity distribution image, the luminance is increased as a whole because the X-rays transmitted through the helical layer 18 are included. Therefore, as shown in FIG. 4B, the scattering intensity of X-rays becomes lower as a whole toward the outside in the radial direction of the high-pressure tank 12.

In the distribution of the scattering intensity, the chevron portion corresponds to the hoop layer 16 and the valley-shaped portion corresponds to the helical layer 18. From here, the feature amount acquisition unit 28 extracts the corresponding scattering intensity of the helical layer 18, and sets a regression equation that can approximate the change (distribution) of the scattering intensity with respect to the radial position coordinates in the helical layer 18. The regression equation to be set may reflect the information of the transmission image of X-rays in the carbon fiber reinforced resin. For example, the regression equation standardizes the scattering intensity by multiplying the ray absorption coefficient of a substance obtained by log-converting the transmittance of X-rays in the laminated body 14 by the thickness of the substance, thereby standardizing the scattering intensity of the substance. It can also be expressed by the ratio of the scattering coefficient and the line absorption coefficient.

In the laminated body 14, for example, the helical layer 18 on the inner side in the radial direction has the thickest layer thickness. Further, the scattering intensity changes more slowly in the portion corresponding to the helical layer 18 than in the portion corresponding to the hoop layer 16. From this, in FIG. 4B, the region 36 in which the scattering intensity gradually changes on the origin O side can be regarded as the scattering intensity of X-rays transmitted through the helical layer 18A.

In the feature amount acquisition unit 28, in the setting of the regression equation (step 102), the region 36 in which the change in the scattering intensity in the radial direction in the scattering intensity distribution image is in a gradual range is extracted. This region 36 corresponds to the helical layer 18A, and the feature amount acquisition unit 28 can approximate the relationship between the pixel position (Y coordinate) in the extracted region 36 and the scattering intensity at the pixel position. The expression f (y) (for example, a linear function of y) is set. The set regression equation f (y) can be verified by using the scattering intensity of the region predicted to correspond to each of the helical layers 18B and 18C. The region for setting the regression equation f (y) is not limited to the region 36 corresponding to the helical layer 18A, and a region that can be predicted to correspond to the helical layers 18B and 18C may be applied, and the helical layer 18A may be applied. Each of the regions that can be predicted to correspond to ~ 18C may be applied. Further, the scattering intensity of the hoop layer 16 may be applied to the setting of the regression equation f (y). As the region used for setting the regression equation f (y), the regression equation f (y) can be stabilized by applying the region 36 in which the change in the scattering intensity is gradual, and the scattering intensity and the scattering in the regression equation f (y) can be stabilized. It is possible to suppress the difference that occurs with the scattering intensity in the intensity distribution image.

Further, the feature amount acquisition unit 28 generates a distribution of the scattering intensity I by differentiating the regression equation f (y) (scattering extreme) from the scattering intensity distribution image (step 104), and the feature amount acquisition unit 28 , Generate a distribution of scattering intensity I with respect to the regression equation f (y). As a result, the distribution of the scattering intensity (mainly the distribution of the scattering intensity in the hoop layer 16) based on the regression equation f (y) (the scattering intensity of the helical layer 18) can be obtained.

Further, the feature amount acquisition unit 28 sets the threshold value Is of the scattering intensity with respect to the distribution of the scattering intensity I (step 106). The threshold Is is set based on a high value (scattering intensity corresponding to the hoop layer 16) and a low value (scattering intensity corresponding to the helical layer 18) in the change of the scattering intensity I based on the regression equation f (y). For example, the difference between the high value and the low value in the scattering intensity I is applied to the threshold Is. The peak value (maximum value and minimum value) may be applied to the high value and the low value of the scattering intensity, and the average value of each peak value may be applied.

In step 108 of FIG. 3, the boundary extraction unit 30 extracts the boundary position based on the threshold value Is. In the extraction of the boundary position, the boundary position is extracted using the threshold Is for the distribution (profile) of the scattering intensity I of the X-ray obtained by subtracting the scattering intensity of the regression equation f (y) from the scattering intensity distribution image of the X-ray. .. The extraction of the boundary position is converted into, for example, a profile showing the distribution of the scattering intensity for extracting the boundary position by using the threshold value Is with respect to the distribution (profile) of the scattering intensity I of X-rays. Specifically, as shown in FIG. 4 (D), the X-ray scattering intensity obtained from the X-ray scattering intensity distribution image is converted into the X-ray scattering intensity I when the threshold Is is regarded as constant. do. As a result, the region corresponding to the hoop layer 16 is determined as a region where the scattering intensity I is larger than the threshold value Is. The region corresponding to the helical layer 18 is a region where the scattering intensity I is smaller (lower) than the threshold value Is on the X-ray scattering intensity distribution image of the laminated body 14.

FIG. 4 (C) is obtained by setting the position Pa for the entire area along the axial direction of the high-pressure tank 12 at the position P of the laminated body 14 and obtaining the distribution of the X-ray scattering intensity I for each of the set positions Pa. ), The distribution image of the scattering intensity is obtained. The distribution image of the scattering intensity in FIG. 4C has a higher contrast than the distribution image of the scattering intensity in FIG. 4A, and the boundary surface B between the hoop layer 16 and the helical layer 18 is clearly distinguished. By setting the threshold Isth using the scattering intensity of X-rays in the helical layer 18, the scattering intensity distribution image of X-rays in the laminated body 14 can be converted into a distribution image of good scattering intensity I with high contrast.

Further, the boundary extraction unit 30 extracts each coordinate position of the boundary surface B (Ba, Bb, Bc, Bd) as the boundary position between layers from the distribution (profile) of the scattering intensity I. FIG. 5A shows a schematic diagram of the distribution image of the X-ray scattering intensity in the laminated body 14 that can be generated by the boundary extraction unit 30, and FIG. 5B shows the position of the boundary surface B. It is shown in the diagram. Further, FIG. 5C shows the measured layer thickness of the hoop layer 16 (16A, 16B) in a schematic diagram.

When the position coordinates of each boundary surface B extracted by the boundary extraction unit 30 are plotted on the scattering intensity distribution image of FIG. 4 (C), the scattering intensity distribution image shown in FIG. 5 (A) is obtained. .. That is, as shown in FIG. 5B, the respective coordinate positions (x-coordinate and y-coordinate) of the boundary surface B are set on the XY coordinates with the tank axis direction as the X axis and the tank radial direction as the Y axis. By plotting, each profile of the boundary surface B is formed.

In step 110 of FIG. 3, the layer thickness calculation unit 32 calculates the layer thickness of each layer based on the position coordinates of each boundary surface B extracted by the boundary extraction unit 30. Further, in step 112, the output unit 34 outputs the calculated layer thickness.

Here, the layer thickness of the layer formed by the two boundary surfaces B is detected by calculating the difference in the position coordinates of the boundary surfaces B adjacent to each other in the thickness direction (layer thickness direction) of the laminated body 14. That is, there is a hoop layer 16A between the boundary surface Ba and the boundary surface Bb, a helical layer 18B between the boundary surface Bb and the boundary surface Bc, and between the boundary surface Bc and the boundary surface Bd. Has a hoop layer 16B. From this, the layer thicknesses of the hoop layers 16A and 16B and the helical layer 18B can be calculated from the position coordinates of the boundary surfaces Ba, Bb, Bc and Bd.

As a result, as shown in FIG. 5C, the layer thickness analysis device 10 detects the layer thickness to obtain a profile showing changes in the layer thickness of the hoop layers 16A and 16B along the axial direction of the high pressure tank 12. can get. The layer thickness of the helical layer 18A can be calculated by measuring the position of the inner peripheral surface of the helical layer 18A, and the layer thickness of the helical layer 18C can be calculated by measuring the position of the outer peripheral surface of the helical layer 18C. ..

As described above, in the layer thickness measuring apparatus 10, the scattering intensity of X-rays is used as the feature amount of the carbon fiber reinforced resin with respect to X-rays, and the regression equation f (y) is set based on the scattering intensity of X-rays in the helical layer 18. do. Further, in the layer thickness measuring device 10, a threshold value is set from the scattering intensity distribution obtained by subtracting the regression equation f (y) from the scattering intensity distribution image, and the hoop layer 16 is based on the distribution of the X-ray scattering intensity based on the set threshold value. Extract the distribution of scattering intensity. As a result, the position of the boundary surface between the hoop layer and the helical layer can be accurately extracted, and the layer thickness of each of the helical layer 18 between the hoop layer 16 and the hoop layer 16 can be easily calculated from the distance between the extracted boundary surfaces. can.

In the present embodiment described above, the scattering intensity (luminance) of X-rays is applied as a feature amount of the fiber-reinforced resin with respect to X-rays. However, as the feature amount of the fiber-reinforced resin with respect to X-rays, if the information has different measurement values between the X-rays transmitted through the first layer and the X-rays transmitted through the second layer in the phase contrast imaging method. good.

Further, various processors other than the CPU may execute the measurement process executed by the CPU reading the software (program) in the above embodiment. As a processor in this case, in order to execute specific processing such as PLD (Programmable Logic Device) whose circuit configuration can be changed after manufacturing FPGA (Field-Programmable Gate Array) and ASIC (Application Specific Integrated Circuit). An example is a dedicated electric circuit or the like, which is a processor having a circuit configuration designed exclusively for it. Further, the distribution derivation process and the probability derivation process may be executed by one of these various processors, or with a combination of two or more processors of the same type or different types (for example, a plurality of FPGAs and a CPU). It may be executed in combination with FPGA, etc.). Further, the hardware-like structure of these various processors is, more specifically, an electric circuit in which circuit elements such as semiconductor elements are combined.

Further, in the above embodiment, the embodiment in which the measurement processing program is stored (installed) in the ROM or the storage in advance has been described, but the present invention is not limited to this. The program may be provided in a form recorded on a recording medium such as a CD-ROM (Compact Disk Read Only Memory), a DVD-ROM (Digital Versatile Disk Read Only Memory), and a USB (Universal Serial Bus) memory. Further, the program may be downloaded from an external device via a network.

10 Layer thickness measuring device 12 High-pressure tank 14 Laminated body 16 (16A, 16B) Hoop layer (one of the first layer and the second layer)
18 (18A, 18B, 18C) Helical layer (the other of the first and second layers)
22 Phase contrast imaging device (imaging means)
26 Imaging unit (imaging means)
28 Feature acquisition unit 30 Boundary extraction unit 32 Layer thickness calculation unit B (Ba, Bb, Bc, Bd) Boundary surface

Claims (1)

A high-pressure tank in which a fiber-reinforced resin is used and a laminated body in which the first layer and the second layer are alternately laminated so that the feature amount with respect to X-rays is different is targeted for analysis, and the first layer and the second layer are analyzed. By irradiating the laminated body with the X-rays transmitted through the laminated body and receiving the X-rays transmitted through the laminated body by the imaging means, the X-rays including the distribution of the feature amounts are transmitted to the laminated body. Image the image,
The distribution of the feature amount of X-rays along the layer thickness direction of the laminated body is acquired from the transmission image, and the regression equation of the feature amount for any one of the first layer and the second layer is obtained. Ask,
The feature amount of the regression equation is differentiated from the transmission image, and the transmission image is used based on a reference value set according to the difference between the feature amount of the first layer and the feature amount of the second layer after the difference. The boundary position between the first layer and the second layer is extracted from the distribution of the features obtained by subtracting the features of the regression equation.
The layer thickness of each of the first layer and the second layer is calculated from each of the extracted boundary positions.
A method for measuring the layer thickness of a laminated body including that.

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