JP4588907B2 - Fracture inspection method and apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fracture portion inspection method and apparatus for inspecting the position and thickness of a fracture portion provided on a hard-to-see object or an invisible object.
[0002]
[Prior art]
In recent years, automatic inspection of difficult-to-see objects and invisible objects is often required in the product inspection process. For example, in a lithium-ion battery, in order to prevent an explosion due to internal liquid leakage, etc., a rupture part called a scribe is provided in a part of the case, and this scribe is broken when the internal pressure rises to prevent an increase in internal pressure. Is configured to do. Therefore, management of the thickness of the fractured portion is very important for ensuring this function.
[0003]
However, there is no easy and accurate method for measuring the thickness of the fractured part, so a dedicated worker uses a three-dimensional measuring machine to measure the cross-sectional shape of the fractured part and determine the difference from the standard thickness. The part thickness is estimated.
[0004]
[Problems to be solved by the invention]
However, the measurement method using the above three-dimensional measuring machine has a problem that the measurement takes too much time and time, and high-speed and high-precision automatic inspection cannot be performed.
[0005]
In view of the above-described conventional problems, an object of the present invention is to provide a fracture portion inspection method and apparatus capable of stably detecting the position and thickness of a fracture portion at high speed, high accuracy, and using X-rays.
[0006]
[Means for Solving the Problems]
The fracture portion inspection method of the present invention is arranged so that one of the inclined surfaces of the V-shaped fracture portion formed on the object is parallel to the line segment connecting the X-ray source and the X-ray imaging tube. In the state, the position and thickness of the fractured portion in the object are detected based on the X-ray captured image emitted from the X-ray source and transmitted through the object. The position and thickness of the object can be detected stably at high speed, with high accuracy, and in particular, by arranging the wall of the fractured part of the object parallel to the line segment connecting the X-ray source and the X-ray imaging tube The contrast of the broken part can be made clear, and the position of the broken part can be reliably detected with a clear contrast.
[0008]
Further, in the step of detecting the thickness of the rupture portion, when calculating the thickness from the image density of breaks in the attenuation coefficient and the captured image of the image density due to the material of the object, detecting the thickness accuracy This is preferable.
[0009]
Further, in the step of detecting the thickness of the breakable portion, at the same time the thickness IMAGING and of the object by imaging a known reference object, it breaks the thickness from the thickness of the reference object and the image density of the breaking portion and the reference product Is more preferable because the thickness can be accurately detected without being affected by the radiation level of the X-ray source or the fluctuation of the gain of the imaging device.
[0010]
The fracture inspection apparatus of the present invention includes an X-ray source that emits X-rays to an object, an X-ray imaging tube that images X-rays transmitted through the object, the X-ray source, and the X-ray imaging. An arrangement unit arranged so that one of the inclined surfaces of the V-shaped fracture portion formed on the object is parallel to a line segment connecting the tube, and a captured image captured by the X-ray imaging tube And a position detecting means for detecting the position of the broken portion in the object and a thickness detecting means for detecting the thickness of the broken portion in the object. The position and thickness of the object can be detected stably at high speed, with high accuracy, and in particular, the arrangement is such that the wall surface of the fracture portion of the object is parallel to the line segment connecting the X-ray source and the object By providing the means, the position of the fracture portion can be detected with clear contrast, which is preferable.
[0012]
Further, the thickness detection hand stage and consists hands stage or al for calculating the thickness from the image density of the breaking portion in the attenuation coefficient and the captured image of the image density due to the material of the object, accurately thickness This is suitable because it can be detected.
[0013]
Further, the thickness detecting means images a reference object having a known thickness simultaneously with the imaging of the object, and calculates the thickness of the fractured part from the fractured part and the image density of the reference object and the thickness of the reference object. It is preferable that the means can detect the thickness with higher accuracy without being affected by the fluctuation of the radiation level of the X-ray source and the gain of the image pickup device.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, an embodiment of a fracture portion inspection method and apparatus according to the present invention will be described with reference to FIGS.
[0015]
FIG. 1 shows a schematic configuration of a fracture inspection apparatus using transmitted X-rays. In FIG. 1, 1 is an X-ray radiation source, 2 is a radiation X-ray, 3 is an object, 4 is an X-ray imaging tube, and 5 is an image for obtaining the position and thickness of the fracture portion 7 in the object 3 from the captured image. The processing device 6 is a captured image monitor.
[0016]
The radiation X-ray 2 travels linearly from the radiation point (focal point) of the X-ray radiation source 1 and is attenuated by the object 3 in the middle while a part thereof reaches the X-ray imaging tube 4 and is imaged. The The fracture portion 7 is thinner than the thickness in the vicinity thereof. Absorption of transmitted X-rays is greater in the vicinity of the thicker portion than the fractured portion 7. For this reason, the broken portion 7 has a large amount of transmitted X-rays and the vicinity thereof has a small amount of X-ray transmission.
[0017]
FIG. 2 shows the positional relationship between the V-shaped cross-sectional shape of the fracture portion 7 and the radiation X-ray 2 at the time of measurement. Thus, at the time of measurement, the object 3 is disposed at an angle with respect to the main axis of the radiation X-ray 2 at an angle. This is to minimize the total thickness of the case that is the object of thickness measurement and relatively increase the ratio of the difference in thickness with respect to the vicinity of the fracture portion 7.
[0018]
Of the two wall surfaces of the V-shaped cross section of the fracture portion 7, one wall surface is approximately the main axis of the radiation X-ray 2, that is, the axis connecting the focal point of the X-ray radiation source 1 and the tube surface center of the X-ray imaging tube 4. They are arranged in parallel. By doing so, the change in the transmitted X-ray dose before and after the slope of the fracture portion 7 becomes steep, and a clear edge appears in the density change of the image captured by the X-ray imaging tube 4 before and after the slope. Therefore, even if the position of the object 3 varies, the position of the fracture portion 7 can be obtained stably by performing an edge search.
[0019]
As shown in FIG. 3, the image processing apparatus 5 includes an A / D converter 10 that converts an image signal from the X-ray imaging tube 4 into digital image data, an image memory 11 that stores image data, and image data. The I / O 12 output to the monitor 6, the edge detecting means 13 for detecting the edge of the breakage portion 7 from the image data of the image memory 11 and determining the position of the breakage portion 7, the thickness of the breakage portion 7 and the thickness thereof as described later. Thickness / coefficient calculating means 14 for calculating a coefficient to be obtained, coefficient storing means 15 for storing the obtained coefficient, output means 16 for outputting the obtained thickness of the fracture portion 7, the edge detecting means 13, the thickness / The coefficient calculation means 14, the coefficient storage means 15, and the control means 17 that controls the output means 16 are configured.
[0020]
FIG. 4 shows an example in which the captured image density in the vicinity of the cross section of the fracture portion 7 is graphed. The vertical axis indicates the image density, and the horizontal axis indicates the position in the horizontal direction (horizontal direction) in FIG. 2. A steep edge rises at the position L, indicating the position of the slope of the fracture portion 7. The edge detection means 13 detects the position of the fracture portion 7 by performing an edge search for detecting the rising edge. The image density I at the rising edge and the thickness of the fracture portion 7 are related, and the thickness is calculated as follows.
[0021]
FIG. 5 shows the relationship between the thickness of the broken portion 7 of the object 3 and the transmitted X-ray dose (captured image density I). The vertical axis represents the image density I, and the horizontal axis represents the thickness T of the fracture portion 7 of the object 3. The relational expression of the image density I with respect to the thickness T is
I = I ₀ · EXP (−μ · T) (I ₀ is the concentration when thickness is 0)
Indicated by For this reason, if two reference objects having the same material as the object 3 and having a known thickness T are separately imaged to obtain the density, I ₀ and μ can be obtained. In FIG. 4, T ₁ and T ₂ are the thicknesses of these reference materials, I ₁ and I ₂ are the respective image densities, and I ₀ and μ are determined from these. The thickness / coefficient calculation means 14 obtains the coefficients I ₀ and μ in this way and stores them in the coefficient storage means 15.
[0022]
When the above equation is converted with respect to the thickness, T = −1 / μ · LN (I / I ₀ ), and therefore the thickness T can be obtained from the coefficients I ₀ and μ and the image density I. Thus, the thickness / coefficient calculating means 14 calculates the thickness T of the fracture portion 7 from the detected image density I and I ₀ and μ stored in the coefficient storing means 15, and the result is output by the output means 16. The
[0023]
In the above description of the embodiment, an example is shown in which two reference objects with known thicknesses T are separately imaged in advance to obtain the density and the coefficients I ₀ and μ are obtained. As shown in FIG. It is also possible to arrange reference objects 8 and 9 having the same material as that of FIG.
[0024]
In this way, the coefficients I ₀ and μ can be calculated each time the thickness of the object 3 is obtained. Therefore, the radiation level of the X-ray radiation source 1 varies and the gain of the X-ray imaging tube 4 varies. In order to obtain the thickness of the fracture portion 7 of the object 3 after recalculating the coefficient using the reference objects 8 and 9 having a known thickness each time the image density level fluctuation caused by Thus, the fluctuation of the measurement result due to the fluctuation can be suppressed to be extremely small.
[0025]
According to the present invention, the thickness and the thickness of a rupture part of a difficult object such as a rupture part for preventing an increase in internal pressure in the case of a lithium ion battery can be accurately and high-speed using X-rays. Automatic inspection can be stably performed.
[0026]
【The invention's effect】
According to the fracture portion inspection method and apparatus of the present invention , one of the inclined surfaces of the V-shaped fracture portion formed on the object with respect to the line segment connecting the X-ray source and the X-ray imaging tube as described above. Since the position and thickness of the fractured portion in the object are detected based on the X-ray captured image that is emitted from the X-ray source and transmitted through the object in a state where the two are arranged in parallel with each other. Using X-rays, the position and thickness of the rupture part can be automatically inspected at high speed, high accuracy, and stably. Especially, the rupture of the object with respect to the line segment connecting the X-ray source and the X-ray imaging tube. By arranging so that the wall surfaces of the portions are parallel, the contrast of the broken portion can be made clear, and the position of the broken portion can be reliably detected with clear contrast.
[0028]
Furthermore, in detecting the thickness of the rupture portion, when calculating the thickness from the image density of breaks in the attenuation coefficient and the captured image of the image density due to the material of the object, detecting the thickness accuracy Can do.
[0029]
Furthermore, in detecting the thickness of the breakable portion, at the same time the thickness IMAGING and of the object by imaging a known reference object, breaks the thickness from the thickness of the reference object and the image density of the breaking portion and the reference product , The thickness can be detected more accurately without being affected by fluctuations in the radiation level of the X-ray source and the gain of the imager.
[Brief description of the drawings]
FIG. 1 is a schematic configuration diagram of a fracture portion inspection method according to an embodiment of the present invention.
FIG. 2 is an explanatory diagram of a positional relationship between a cross-sectional shape of a fracture portion and radiation X-rays according to the embodiment.
FIG. 3 is a configuration diagram of an image processing apparatus according to the embodiment.
FIG. 4 is a graph showing an image density in the vicinity of a cross section of a fracture portion in the same embodiment.
FIG. 5 is a graph showing the relationship between the thickness of an object and the image density.
FIG. 6 is a schematic configuration diagram of a fracture portion inspection method according to another embodiment of the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 X-ray radiation source 2 Radiation X-ray 3 Object 4 X-ray imaging tube 5 Image processing apparatus 7 Breaking part 8, 9 Reference object 13 Edge detection means 14 Thickness / coefficient calculation means

Claims (6)

Radiation from the X-ray source in a state where one of the inclined surfaces of the V-shaped fractured portion formed on the object is parallel to the line segment connecting the X-ray source and the X-ray imaging tube And detecting the position and thickness of the breakage portion in the object based on an X-ray captured image transmitted through the object. In the step of detecting the thickness of the fracture portion,
2. The fracture portion inspection method according to claim 1, wherein the thickness is calculated from an attenuation coefficient of image density due to the material of the object and an image density of the fracture portion in the captured image. In the step of detecting the thickness of the fracture portion,
2. The fracture according to claim 1, wherein a reference object having a known thickness is imaged simultaneously with the imaging of the object, and the fracture part thickness is calculated from the image density of the fracture part and the reference object and the thickness of the reference object. Department inspection method. An X-ray source that emits X-rays to an object;
An X-ray imaging tube for imaging X-rays transmitted through the object;
Arranging means for arranging one of the inclined surfaces of the V-shaped fracture portion formed on the object in parallel with a line segment connecting the X-ray source and the X-ray imaging tube ;
Position detecting means for detecting the position of the fracture portion in the object from the captured image captured by the X-ray imaging tube;
A breaking portion inspection apparatus comprising: a thickness detecting means for detecting a thickness of a breaking portion in the object. The thickness detecting means includes
5. The fracture portion inspection apparatus according to claim 4, further comprising means for calculating a thickness from an attenuation coefficient of image density due to the material of the object and an image density of the fracture portion in the captured image. The thickness detecting means includes
It comprises means for imaging a reference object having a known thickness at the same time as imaging of the object, and calculating the thickness of the fracture part from the image density of the fracture part and the reference object and the thickness of the reference object. The fracture | rupture part inspection apparatus of Claim 4.

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