WO2018092256A1

WO2018092256A1 - Inline x-ray inspection system and imaging method for inline x-ray inspection system

Info

Publication number: WO2018092256A1
Application number: PCT/JP2016/084189
Authority: WO
Inventors: 定岡　紀行
Original assignee: 株式会社日立製作所
Priority date: 2016-11-18
Filing date: 2016-11-18
Publication date: 2018-05-24

Abstract

The purpose of the present invention is to prevent the degradation of internal defect detection accuracy resulting from increased scattered ray component generation between detection elements when a planar detector in which detection elements are densely arranged in two dimensions is used for the purpose of shortening imaging while raising X-ray energy such that X-rays will pass through metal products such as mass-produced castings, and to thereby provide an inline X-ray inspection system capable of highly accurate inline X-ray inspection. To achieve this purpose, this inline x-ray inspection device system, which has a radiation source (1) for irradiating radiation, a detector (2, 5) for detecting the radiation that has passed through a subject to be imaged, a driving mechanism (4) for moving the subject between the radiation source and the detector, a signal processing circuit (8) for quantifying the amount of transmitted radiation measured by the detector, and a calculation device (9) for constructing an image on the basis of signals from the signal processing circuit (8), is characterized by having, as a detection system, a two-dimensional-element-array detector unit (2) having shielding elements partially embedded therein and a two-dimensional-element-array detector unit (5) and in that a transmission image is created using images of the same subject imaged by the two detector units.

Description

X-ray inline inspection system and imaging method of X-ray inline inspection system

The present invention relates to an apparatus and a method for continuously imaging an internal state in a production line of a mass-produced machine part having a complicated shape, nondestructively.

In the soundness and quality inspection in the production line of mass-produced machine parts typified by automobile casting parts, 100% inspection is required to enhance reliability. In the inspection of mass-produced machine parts, dimension / shape measurement is the main evaluation item, but in mass-produced cast products, in addition to dimensional inspection, it is important to detect internal defects that may occur during the casting process. Dimensional shape measurement on the outside of the product can be measured from images taken by optical systems such as laser rangefinders and cameras. However, in evaluating internal defects in mass-produced castings, it is necessary to measure the inside of the product nondestructively. is there. The most effective measuring means for nondestructive inspection inside a product is X-ray transmission image and CT image measurement. Even with ultrasonic waves, the presence or absence of internal defects can be measured to some extent, but since it is necessary to bring the probe into contact with the product itself, it is difficult to handle a three-dimensional complicated shape product such as a cast part.

In X-ray transmission image and CT image measurement, a target object may be installed between the X-ray source and the detector, and the internal state measurement evaluation without contact with the target object is possible. In addition, in X-ray transmission image and CT image measurement, not only internal defect measurement but also internal complicated three-dimensional shape and dimension measurement that cannot be measured from the outside can be evaluated from the captured image.

Even in the case of non-mass cast products, assembly products may require evaluation of the soundness of the internal state without removing the outer casing. In this case as well, transmission image and CT image measurement using X-rays is an effective measurement means.

In 100% inspection in these production lines, since products are manufactured continuously in a short time, it is necessary to measure the physical quantities necessary for soundness evaluation continuously at short time intervals and determine the presence or absence of soundness. . In order to evaluate internal defects continuously and in a short time with high accuracy by X-ray transmission image and CT image measurement, it is necessary to obtain a projection image of the entire product with a two-dimensional planar detector. In this case, the scattered radiation generated between the detectors becomes image noise and deteriorates the measurement accuracy. In particular, in a metal product such as a mass-produced cast product, it is necessary to increase the X-ray energy in order to transmit X-rays. In this case, the scattered radiation component generated between detectors increases.

International Publication No. 2010/074031

Conventionally, internal defect inspections for mass-produced cast products have been carried out by destructive inspection by sampling and acoustic evaluation by hammering sound, etc., and not by 100% inspection by manufacturing lions. In addition, in products such as mounted circuit boards, defect inspection using X-rays on the production line is performed on all products, but the product thickness is much thinner than mass-produced cast parts, so X-ray energy The scattered radiation component generated between the detectors is small and does not cause a problem.

On the other hand, as described above, in a metal product such as a mass-produced cast product, it is necessary to increase the X-ray energy in order to transmit X-rays, and at the same time, it is necessary to perform imaging in a short time. Need to be used. When high-energy X-rays are transmitted through a flat detector in which the detection elements are densely arranged, scattered ray components generated between the detection elements increase, and the internal defect detection accuracy is deteriorated.

Further, in Patent Document 1, a partial image of a target product is captured by a combination of an X-ray tube and a two-dimensional planar detector in an in-line inspection of a mounted circuit board, and the X-ray tube and a two-dimensional image are taken for the entire region. An X-ray inspection method and an inspection apparatus have been devised that move by a combination of flat-type detectors to image the entire area of the target product. However, when the target is a metal mass-produced cast product, a high X is required to transmit the product. Line energy is required. In this case, since the scattered radiation component generated between the detection elements of the two-dimensional flat detector increases and the image noise becomes high, this configuration is difficult to apply to a metal mass production casting.

Therefore, the object of the present invention is made in the background as described above, and in order to transmit X-rays in a metal product such as a mass-produced cast product, the X-ray energy can be increased and at the same time. In order to realize imaging, when a planar detector in which detector elements are densely arranged in two dimensions is used, internal defect detection accuracy deterioration due to an increase in scattered ray components generated between detector elements is prevented, and high accuracy is achieved. An object of the present invention is to provide an X-ray in-line inspection system that realizes in-line X-ray inspection.

For the above purpose, in the present invention, when the target mass production casting product first flows into the production line, the shielded element built-in type two-dimensional element array detector and the two-dimensional element array detector respectively perform transmission imaging. Then, after calculating the difference between the two, the difference is subtracted from the transmission image of each mass-produced cast product flowing in the production line to generate a transmission image of each cast product. In addition, in order to acquire each image in each of the above processes, a detector unit consisting of a two-dimensional element array detector and a detector unit including a shield element built-in type two-dimensional element array detector are simultaneously held as a detection system, These two detector units have equipment position structures that can be installed independently of each other at a position where a transmission image can be taken with respect to a cast product flowing on the production line.

According to the present invention, detection elements are densely arranged two-dimensionally in order to increase the X-ray energy in order to transmit X-rays in a metal product such as a mass-produced cast product and at the same time to realize imaging in a short time. To provide an X-ray in-line inspection system that prevents internal defect detection accuracy from deteriorating due to an increase in scattered radiation components generated between detection elements when a flat detector is used, and realizes high-precision in-line X-ray inspection. Is possible.

It is a flowchart which shows the procedure of the transmission image imaging method of the X-ray in-line inspection system by Example 1. FIG. 1 is a schematic view of an X-ray in-line inspection system according to Embodiment 1. FIG. 2 is an example of in-line inspection of a mass-produced cast product sample of the X-ray in-line inspection system according to Example 1. FIG. It is a figure which shows the example of a transmission image at the time of imaging the mass-production casting sample of imaging object with the X-ray in-line inspection system by Example 1. FIG. It is a flowchart which shows the procedure of the transmission image imaging method of the X-ray in-line inspection system by Example 2. It is the schematic of the X-ray in-line inspection system by Example 2. It is a figure which shows the transmission image simulation result at the time of imaging the mass-production casting product sample of imaging object with the X-ray in-line inspection system by Example 2. FIG. FIG. 10 is a flowchart illustrating a procedure of a transmission image capturing method of the X-ray inline inspection system according to the third embodiment.

Hereinafter, preferred embodiments for carrying out the present invention will be described with reference to the drawings. In addition, the following is only an Example, and it cannot be overemphasized that the content of invention is not limited to the following aspect.

FIG. 1 is a flowchart showing a procedure of a transmission image capturing method for capturing a transmission image of a target product in a production line by the X-ray inline inspection system of the first embodiment, and FIG. 2 is an X-ray inline of the present embodiment. FIG. 3 is a schematic diagram of an inspection system, FIG. 3 is an example of in-line inspection of a mass production casting product sample in the X-ray in-line inspection system of the present embodiment, and FIG. 4 is an imaging method of the mass production casting product sample of FIG. An example of a transmission image when captured is shown.

In the imaging method of the first embodiment, first, in S100, the first one of the products to be inspected is installed on the belt conveyor 4 of the present inspection system apparatus. Next, the inspection target product is moved by the belt conveyor 4 and is set at the position of the shielding element built-in type two-dimensional element array detector unit 2 in S101. At this position, it is set at a position facing the X-ray tube 1 with respect to the mass-produced cast product sample 10 to be imaged. As shown in FIG. 2, the apparatus according to the first embodiment includes two types of detector units, a shield element-embedded two-dimensional element array detector unit 2 and a two-dimensional element array detector unit 5, and these detector units. However, the detector unit support structure 7 has a structure installed at a position facing the X-ray tube 1. X-rays, γ-rays, and neutrons can be selected as a radiation source that transmits the mass-produced casting to be imaged. As the X-ray source, an X-ray tube is used at a voltage of 600 kV or less, and a linear accelerator (LINAC) is used at 1 MV or more.

Shielding element built-in type two-dimensional element array detector unit 2 includes detection elements 3 arranged in a square lattice shape, and these detection elements 3 and shielding elements 6 arranged on staggered. The detection element 3 is composed of a semiconductor element such as Si or CdTe or a scintillator type detector element, and detects radiation flowing into the element. On the other hand, the shielding element 6 is made of lead, tungsten, or the like, and shields scattered rays from detection elements adjacent to each direction. A collimator is provided in front of each detection element 3. The inspection object product is moved by the belt conveyor 4 and set at the position of the shielding element built-in type two-dimensional element array detector unit 2 in S101, and then irradiated with X-rays from the X-ray tube 1, and in S102 Transmission image data A101 is acquired. When acquiring the transmission image data A101 of the target product, in order to acquire transmission image data at each shielding element position, the vertical and horizontal lengths of the shielding element 6 are moved to acquire transmission image data on the entire surface.

Furthermore, in the X-ray in-line inspection system apparatus in the first embodiment, the signal processing circuit 8 that digitizes the radiation transmission amount measured by the detector, and the imaging data calculation / storage that performs the following calculation and further stores and displays the data. A display device 9 is provided.

Next, the mass production cast product sample 10 is moved to the installation position of the two-dimensional element array detector unit 5 by the belt conveyor 4 in S103 of FIG. At the same time, the mass production casting product sample 10 to be imaged with the X-ray tube 1 is set at a position facing the two-dimensional element array detector unit 5. FIG. 3 shows the set state. The two-dimensional element array detector unit 5 is a detector unit in which the detection elements 3 are arranged in a square lattice pattern on a two-dimensional plane. Since the shielding element 6 is not provided unlike the shielding element built-in type two-dimensional element array detector unit 2 and the projection surface of the mass-produced casting sample 10 to be imaged can be received by the two-dimensional element array detection element, Unlike the shielded element built-in type two-dimensional element array detector unit 2, it is not necessary to move the detector in the vertical and horizontal directions of the shield element, and in S104 of FIG.

Thereafter, in S105 of FIG. 1, the difference amount between the transmission image data A101 and the transmission image data B102 of the mass-produced cast product sample 10 is calculated. In FIG. 4, a shielded element built-in type two-dimensional element array detection is performed using the transmission image simulator. An example of a transmission image obtained by trial calculation of the transmission image data A101 of the mass-produced cast product sample 10 by the vessel unit 2 and the transmission image data B102 of the mass-production cast product sample 10 by the two-dimensional element array detector unit 5 is shown. In the transmission image 13 of the mass-produced cast product sample 10 by the shield element built-in type two-dimensional element array detector unit 2, the scattered radiation from the adjacent detector element 3 is cut by the shield element 6 provided around the detector element 3. Therefore, a clear transmission image 13 with little image noise is obtained. On the other hand, in the transmission image 14 of the template region by the two-dimensional element array detector unit 5, since the scattered radiation from the adjacent detection elements 3 enters each detection element 3, a transmission image 14 with much image noise is obtained. However, when the transmission image 13 of the mass-produced cast product sample 10 is captured by the shielding element built-in type two-dimensional element array detector unit 2, the shielding element built-in type two-dimensional element array detector unit 2 is moved in the vertical and horizontal directions by the size of the shielding element. A transmission image capturing time is required to capture a transmission image of the entire region. On the other hand, when the transmission image 14 of the casting mold region is picked up by the two-dimensional element array detector unit 5, since the detection elements 3 are arrayed in the entire projection surface region of the mass-produced cast product sample 10 to be imaged, the transmission image is instantaneously generated. can get.

As described above, in S105 of FIG. 1, the transmission image data B102 of the mass-produced cast product sample 10 by the two-dimensional element array detector unit 5 and the mass-produced cast product sample 10 by the shield element-embedded two-dimensional element array detector unit 2 are used. The amount of difference from the transmission image data A101 is calculated. The difference amount data C103 at each detection element position obtained here is the amount of scattered radiation that flows from each detection element to the adjacent detection element in the two-dimensional element array detector unit 5.

In the next step, as S106 in FIG. 1, by subtracting the difference amount data C103 of each inspection element position calculated in S105 from the transmission image data B102 of the mass-produced cast product sample 10 by the two-dimensional element array detector unit 5. The transmission image imaging data D104 from which the scattered radiation component flowing into the adjacent detection element from each detection element is removed is obtained.

In the in-line inspection by the system of Example 1, the soundness of the first mass-produced cast product sample 10 is evaluated in S107 using the transmission image data D104.

Next, in S108, a mass production casting product (second mass production casting sample 11, third mass production casting sample 12) continuously produced on the production line is continuously installed on the belt conveyor 4. The For the second and subsequent mass-produced cast products, imaging by the shielding element built-in type two-dimensional element array detector unit 2 is omitted, and only imaging by the two-dimensional element array detector unit 5 in S105 is performed (S109). Thereby, transmission image data E105 of the second and subsequent mass-produced cast products is obtained.

Next, the difference amount data C103 of each inspection element position calculated in the first is subtracted from the transmission image data E105 of the second and subsequent mass production castings (S110), and the scattered radiation component of the second and subsequent mass production castings is obtained. The removed transmission image data F106 is calculated. Using this transmission image data F106, the soundness of the second mass-produced cast product sample 11 is evaluated in S111. In S112, the processes from S108 to S111 are repeated with respect to the total number of mass-produced castings that are continuously charged.

As described above, according to the first embodiment, in order to transmit X-rays in a metal product such as a mass-produced cast product, X-ray energy is increased, and at the same time, in order to realize imaging in a short time, the detection elements are densely arranged in two dimensions. An X-ray in-line inspection system that prevents internal defect detection accuracy from deteriorating due to an increase in scattered radiation components generated between detection elements and realizes high-precision in-line X-ray inspection when using a planar detector arranged in It can be provided.

FIG. 5 is a flowchart showing a procedure of a transmission image capturing method of the X-ray inline inspection system according to the second embodiment, and a schematic diagram of the X-ray inline inspection system apparatus is shown in FIG.

In the second embodiment, in the line of the belt conveyor 4 for moving the imaging target product, the rotary table 15 that rotates the imaging target product to a position where the shielding element built-in type two-dimensional element array detector unit 2 and the X-ray tube 1 face each other. Provide. In addition, a rotary table 16 for rotating the imaging target product is provided at a position where the two-dimensional element array detector unit 5 and the X-ray tube 1 face each other. In the second embodiment, as shown in the process flow diagram of FIG. 5, the irradiation angle θ of the target product is set by the rotary table 15 of FIG. 5 in S114, and the steps from S101 to S106 are repeated for each set irradiation angle θ. FIG. 7 shows a transmission image simulation in which a transmission image of the mass-produced cast product sample 10 is taken every 90 degrees. FIG. 6 shows (a) a transmission image 17 with an irradiation angle θ = 0 degrees, (b) a transmission image 18 with θ = 90 degrees, (c) a transmission image 19 with θ = 180 degrees, and (d) θ = 270. A transmission image 20 of the degree is shown.

As shown in the processing flow of FIG. 5, after the first mass-produced cast sample 10 is processed in S100 to S114, Null mass-produced cast samples that are continuously produced are processed in S108 to S112. Repeat the process.

As described above, according to the second embodiment, it is possible to inspect with higher accuracy even for internal defects of mass-produced castings that cannot be obtained from one direction.

FIG. 8 is a flowchart showing the procedure of the transmission image capturing method of the X-ray in-line inspection system according to the third embodiment.

In the first and second embodiments, an example of soundness evaluation using a transmission image is shown. In the third embodiment, the shielding element-embedded two-dimensional element array detector unit 2 and the X-ray are configured in the apparatus configuration shown in FIG. Projection data at a specified angle pitch for one rotation of the target product is acquired using the rotary table 15 that rotates the imaging target product to a position where the tube 1 is opposed, and the image reconstruction processing step S117 is performed based on these projection data. Create a dimensional CT image. Also, a three-dimensional CT image is created by the same image reconstruction processing step S118 at the position of the rotary table 16 for rotating the imaging target product provided at the position where the two-dimensional element array detector unit 5 and the X-ray tube 1 face each other. The soundness of the target product is evaluated from the obtained three-dimensional CT image.

As described above, according to the third embodiment, since a three-dimensional CT image is created, it is possible to obtain image data that makes it easier to determine the internal defect.

As described above, according to the present invention, in order to transmit X-rays in a metal product such as a mass-produced cast product, X-ray energy is increased, and at the same time, imaging in a short time is realized in two dimensions. X-ray that realizes high-precision inline X-ray inspection by preventing deterioration of internal defect detection accuracy due to an increase in scattered radiation components generated between detection elements when a planar detector with densely arranged detection elements is used An in-line inspection system can be provided, which can lead to an improvement in the quality of mass-produced statues on the production line. Further, not only casting products but also general machine parts can be visualized on the production line by nondestructive internal structure, which can lead to improvement of the quality of these machine parts.

In addition, this invention is not limited to the above-mentioned Example, Various modifications are included. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, it is possible to add, delete, and replace other configurations for a part of the configuration of each embodiment.

DESCRIPTION OF SYMBOLS 1 X-ray tube 2 Shielding element built-in type two-dimensional element arrangement detector unit 3 Detection element 4 Belt conveyor 5 Two-dimensional element arrangement detector unit 6 Shielding element 7 Detector unit support structure 8 Signal processing circuit 9 Imaging data calculation, storage, Display device 10 Mass production cast sample 11 Second mass production cast sample 12 Third mass production cast sample 13 Transmission image 14 Transmission image 15 Rotary table 16 Rotary table 17 Transmission image 18 θ = 0 ° θ = 90 ° Transmission image 19 θ = 180 degrees transmission image 20 θ = 270 degrees transmission image 101 transmission image data A
102 Transmission image data B
103 Difference data C
104 Transmission image data D
105 Transmission image data E
106 Transmission image data F

Claims

A radiation source that emits radiation;
A detector for detecting radiation transmitted through the subject to be imaged;
A drive mechanism for moving a subject between the radiation source and the detector;
A signal processing circuit for quantifying the radiation transmission amount measured by the detector;
In the X-ray in-line inspection system comprising an arithmetic unit that constructs an image based on these signals,
A two-dimensional element array detector unit partially embedded with a shielding element as a detection system, and a secondary element element array detector unit;
A transmission image is created using images captured by a two-dimensional element array detector unit in which the shielding element is partially embedded in the same subject and the secondary element element array detector unit. X-ray in-line inspection system.
In the X-ray in-line inspection system according to claim 1,
An X-ray in-line inspection system using a two-dimensional element array detector unit partially embedded with the shielding element and a semiconductor detector or a scintillator type detector as the detection element of the two-dimensional element array detector unit .
The X-ray in-line inspection system according to claim 2,
An X-ray in-line inspection system, wherein the two-dimensional element array detector unit in which the shielding elements are partially embedded has shielding elements arranged in a staggered manner in the two-dimensional array of detection elements.
In the X-ray in-line inspection system according to claim 1,
The arithmetic unit obtains a difference between a two-dimensional element array detector unit partially embedded with the shielding element and an image obtained by the two-dimensional element array detector unit, and uses the difference to determine the two-dimensional An X-ray in-line inspection system having a function of subtracting a difference from a new image obtained by an element array detector unit.
In the X-ray in-line inspection system according to claim 1,
The X-ray in-line inspection system, wherein the drive mechanism includes a rotary table that rotates a subject.
A radiation source that emits radiation;
A detector for detecting radiation transmitted through the subject to be imaged;
A drive mechanism for moving a subject between the radiation source and the detector;
A signal processing circuit for quantifying the radiation transmission amount measured by the detector;
In an imaging method by an X-ray in-line inspection apparatus system comprising an arithmetic unit that constructs an image based on these signals,
The detector comprises a two-dimensional element array detector unit partially embedded with a shielding element and a secondary element element array detector unit,
A two-dimensional element array detector unit in which the shielding element is partially embedded and a secondary element element array detector unit are respectively provided for an object to be input at the beginning of a product of the same shape that is continuously input. Take a transmission image independently,
A difference amount between the two image data is calculated,
Subtract the difference amount calculated by the subject initially input from the transmission image picked up by the secondary element element array detector unit for the continuously input subject, and perform soundness determination based on the image An imaging method for an X-ray in-line inspection system characterized by the above.
In the imaging method of the X-ray in-line inspection apparatus system in Claim 6,
In the two-dimensional element array detector unit in which the shield elements are partially embedded, the shield elements are arranged in a staggered manner in the two-dimensional array of detection elements. The line in-line inspection apparatus system is characterized in that a transmission image of the entire region is acquired by moving the image in the vertical and horizontal directions by the length of each line.
In the imaging method of the X-ray in-line inspection apparatus system in Claim 6,
Imaging of an X-ray in-line inspection apparatus system characterized in that a subject is rotated when a transmission image is captured by the two-dimensional element array detector unit in which the shielding element is partially embedded and the secondary element element array detector unit. Method.
In the imaging method of the X-ray inline inspection apparatus system in Claim 8,
An imaging method of an X-ray in-line inspection apparatus system, wherein a CT image is reconstructed from the transmission image.