JP2007212366A - Method and device for inspecting thickness of inspected part - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inspecting device for the thickness of an inspected part capable of obtaining an accurate residual thickness measurement result even when the inspected part hardly transmits visible light by utilizing the transmitting characteristic of X-rays. <P>SOLUTION: The inspecting device comprises an X-ray source 2 for radiating the X-rays 3 to be radiated to a specimen 6, an X-ray brightness measuring instrument 5 for measuring the brightness of the X-rays that is arranged on the opposite side of the X-ray source while an inspection space 8 for radiating the X-rays to the specimen is disposed, a transferring means 7 for passing the specimen in the inspection space at a predetermined speed, and a controller 12 that controls the transferring means, X-ray brightness measuring instrument, and X-ray source, calculates the thickness of the inspected part based on the measured brightness of the X-rays, and determines whether the thickness of the inspected part is within a desired range. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method and apparatus for inspecting the thickness of a portion to be inspected, and in particular, using X-rays, a method for inspecting the thickness of an invisible processing portion of an automobile synthetic resin interior product called a so-called instrument panel, and Relates to the device.

  The quality inspection of an instrument panel, which is one of automotive interior parts, includes an item of so-called invisible processed part formed in a groove shape on the panel, that is, a measurement of the remaining thickness of the groove part. As shown in FIG. 8, the method of measuring the remaining thickness that is currently being carried out irradiates the test portion 23 with visible light 25 from the light source 24, and transmits the light transmitted through the groove-like portion 22 that is the test portion 23. The light receiving device 26 captures the remaining thickness or quality of the groove-like portion 22 in accordance with the amount of light.

  When the cross section of the groove-like portion 22 of the subject 27 shown in FIG. 9 is actually imaged by X-ray CT, the groove-like portion 22 has an appropriate depth as shown in FIGS. In addition to those in which grooves are formed and the cross-sectional shape is not collapsed, as shown in FIGS. 10D to 10F, there are those in which the cross-sectional shape is broken even if the grooves are formed at an appropriate depth. You can see that it exists.

  Therefore, in the current method using visible light, even if the remaining thickness of the groove-like portion of the test portion 23 is appropriate, the visible light 25 cannot be transmitted well due to the collapse of the cross section or the like. ), There is a problem that the amount of transmitted light is insufficient and the product is determined as a defective product, or the reliability of the inspection result is lowered. On the other hand, FIG. 11A is a luminance graph of a portion where the cross section is not broken. In FIG. 11, the horizontal axis indicates the position, and the vertical axis indicates the amount of transmitted light at that portion. In addition, since visible light 25 has low substance permeability, high-precision inspection should be performed when the portion 23 to be examined is thick, made of a material that does not easily transmit visible light 25, or an opaque color. There is a problem that can not be.

  On the other hand, Patent Document 1 discloses a foreign object detection device that uses X-rays as energy rays applied to a portion to be examined. The foreign object detection device described in Patent Document 1 is arranged so that a test part can pass on an X-ray path, and pulses X-rays toward the test part when passing through the test part. The X-ray sensor detects the transmitted X-rays, detects the foreign matter by visually capturing the shape and size of the subject.

Another example of using X-rays as energy rays is the fruit selection device described in Patent Document 2. The fruit selection apparatus described in Patent Document 2 includes an X-ray source and an X-ray detector arranged to face each other so as to sandwich a fruit passing on an X-ray path by a transfer unit, and the X-ray transmitted through the fruit. The quality of the fruit as the subject is determined according to the detection level.
JP-A-9-269380 JP-A-62-273087

  However, the apparatus described in Patent Document 1 has the following problems. 1stly, since the apparatus of patent document 1 is not comprised so that the thickness of a test part can be measured, the thickness of a test part cannot be known. Secondly, in the apparatus described in Patent Document 1, since pulsed X-rays are used, when the test part is continuous or equivalent, or the test part is continuously inspected. It is unsuitable when it is necessary to do so. Thirdly, both the means for confirming that the subject passes through the X-ray path and the control means for controlling the radiation of the pulsed X-ray by the detection signal are required, and the structure becomes complicated. . Fourthly, there is a problem that there is no configuration for shielding X-rays, and there is a risk that the line X is scattered around. Similar to the device described in Patent Document 1, the device configuration described in Patent Document 2 does not have a structure for shielding X-rays, and there is a possibility that X-rays may be scattered around.

    The present invention was created in view of the above points, and by using the transmission characteristics of X-rays, a highly accurate residual thickness measurement result is obtained even when it is difficult for the test portion to transmit visible light. It is an object of the present invention to provide a method for inspecting a thickness of a portion to be inspected and an apparatus using the same.

  In order to achieve the above object, the method for inspecting a thickness of a subject of the present invention irradiates a subject portion of a subject with X-rays, detects a transmitted X-ray dose that has passed through the subject, The thickness of the test part is calculated from the measured value of the transmitted X-ray dose corresponding to the above, and it is determined whether or not the thickness of the test part is within a desired range.

In the method for inspecting the thickness of the test part of the present invention, preferably, the brightness of the X-ray transmitted through the test part is used as the measurement value of the transmitted X-ray dose.
In the method for inspecting the thickness of the test part according to the present invention, the measurement value of the transmitted X-ray brightness is x, and the remaining thickness z of the test part is a linear function z = ax + b (where a is irradiated with X-rays). It is desirable to calculate from a coefficient specific to the substance, and b is a constant specific to the substance.

  In order to achieve the above object, a method for inspecting a thickness of a test part according to the present invention includes a first step of irradiating a test part of the subject with X-rays while transferring the test object, A second step of detecting the transmitted X-rays by the X-ray line sensor, a third step of obtaining the luminance of the X-ray dose transmitted through the test portion from the detection result, and the thickness of the test portion based on the luminance of the X-ray dose And a fourth step of determining whether or not the thickness of the test portion is within a desired range.

In order to achieve the above object, an inspection apparatus for a thickness of an inspection part according to the present invention includes an X-ray source for emitting X-rays to be irradiated on a subject, and an inspection for irradiating the subject with X-rays. An X-ray luminance measuring device for measuring the luminance of X-rays disposed relative to the X-ray source in a space, and a transfer means for passing the subject at a predetermined speed in the examination space; The transfer means, the X-ray luminance measuring device and the X-ray source are controlled, and the thickness of the test part is calculated from the measured X-ray brightness and the thickness of the test part is within a desired range. And a control device for determining whether or not.
In the inspection apparatus for the thickness of the test part according to the present invention, preferably, the X-ray luminance is x, and the remaining thickness z of the test part is a linear function z = ax + b (where a is a substance that irradiates X-rays). It is a specific coefficient, and b is a constant specific to the substance).

  According to the present invention, first, by utilizing the X-ray transmission characteristic, there is an effect that a highly accurate remaining thickness measurement result can be obtained even when the test portion is difficult to transmit visible light. .

  Secondly, the test part is continuously or intermittently inspected by continuously passing X-rays through the examination space using the transfer means. There is an effect that can be. As a result, there is an effect that a continuous residual thickness measurement result can be obtained over the entire series of grooves formed intermittently on the instrument panel made of synthetic resin. Furthermore, since the measurement can be performed continuously, there is an effect that the formation pitch of the groove-like portion formed intermittently with respect to the test portion can be confirmed.

  Thirdly, by covering the inspection space with X-ray shielding means having X-ray shielding properties, there is an effect that the remaining thickness measurement or the groove-shaped pitch measurement can be performed with high safety while having a simple configuration. is there.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram showing a configuration of a test portion thickness inspection apparatus 1 according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the subject 6 to be inspected by the inspection apparatus 1 according to the embodiment of the present invention. FIG. 3 shows an embodiment of a flowchart relating to control and operation of the inspection apparatus 1 shown in FIG.

  As shown in FIG. 1, an inspection apparatus 1 for a thickness of an object to be inspected passes through an X-ray source 2, a slit 4 for appropriately focusing the X-ray 3 emitted from the X-ray source 2, and the slit 4 The X-ray line sensor 5 for detecting the X-ray 3 that has traveled straight, the conveyor 7 for passing the subject 6 on the path of the X-ray 3, the X-ray source 2, and the X-ray line sensor 5 An examination space 8 for irradiating the subject 6 with X-rays 3 while passing the subject 6 therebetween, an X-ray shielding box 9 surrounding the examination space 8, an X-ray source 2 and an X-ray line The sensor 5 and the conveyor 7 are controlled, and whether the remaining thickness z ′ of the test portion 10 and the pitch p of the groove-shaped portion 11 are correct or not is freely determined based on the transmitted X-ray luminance detected by the X-ray line sensor 5. A computer 12 is provided.

The on / off timing of the X-ray source 2 is controlled by the computer 12. In the on state, X-rays 3 are continuously emitted in a predetermined direction. The radiated X-ray 3 can be of an energy level that is reduced to such an extent that the luminance of the transmitted X-ray 3 becomes an appropriate value when the maximum thickness portion of the subject 6 is transmitted.
The slit 4 is for appropriately narrowing down the X-ray 3 emitted from the X-ray source 2. Of course, the slit 4 may be built in the X-ray source 2 in advance.

  The X-ray line sensor 5 is disposed in front of the X-ray source 2 in the traveling direction of the X-ray 3 narrowed down by the slit 4. This arrangement position is a position between the band 13a on the side where the subject 6 is placed in the endless band of the conveyor 7 and the band 13b on the opposite side. With this arrangement, the X-ray 3 radiated toward the subject 6 is configured so as not to transmit a substance other than the subject 6 as much as possible before reaching the X-ray line sensor 5, and energy loss. And the number of exposed parts can be reduced. A conventionally known X-ray line sensor 5 can be used.

  The conveyor 7 has an annular endless band 14 in which both ends of a band having a predetermined width made of a substantially homogeneous material capable of transmitting X-rays 3 are joined. Further, the conveyor 7 has a pair of rollers 15 that are in close contact with the inner peripheral surface of the endless belt 14 and rotate the endless belt 14. The operation of the roller 15 (the timing and speed of its rotation) is controlled by the computer 12.

  The examination space 8 is defined as a space of an appropriate size that allows the subject 6 placed on the band 13a to pass between the slit 4 and the upper band 13a of the endless band 14 of the conveyor 7. It is made. The subject 6 is configured to be irradiated with X-rays 3 when passing through the examination space 8.

  The X-ray shielding box 9 is made of a material such as lead having X-ray shielding properties, and includes the entire inspection space 8 and the conveyor 7 and slit 4, the X-ray source 2, and the entire X-ray line sensor 5 positioned immediately below the inspection space 8. It is formed in a box shape to surround.

  The computer 12 is configured to control the X-ray source 2, the X-ray line sensor 5 and the conveyor 7. Further, the computer 12 determines whether the remaining thickness z ′ of the test portion 10 and the pitch p of the groove-shaped portion 11 are correct based on the transmitted X-ray luminance detected by the X-ray line sensor 5. It can be performed freely based on the above.

  The subject 6 is made of synthetic resin and has a plurality of groove-like portions 11 having a substantially constant length L formed intermittently at a predetermined pitch p, as shown in FIG. The test part 10 extends over the entire series of groove-like parts 11 formed in the subject 6.

An example of the operation procedure of the inspection portion thickness inspection apparatus 1 configured as described above will be described with reference to the flowchart shown in FIG.
As shown in FIG. 3, first, in step S1, the entire inspection device thickness inspection apparatus 1 is activated, and it is determined whether or not the subject 6 is present at the starting end 16 of the conveyor 7 (step S2). If the subject 6 is present at the start end 16, the conveyor 7 is activated by the computer 12 in step S 3, and the conveyor 7 rotates to place the subject 6 on the start end 16 in the examination space inside the X-ray shielding box 9. Transfer to 8 In step S <b> 4, it is confirmed that the transferred subject 6 exists at the examination position in the examination space 8. When the presence is confirmed, the X-ray source 2 is started by the computer 12 in step S5, and the subject 6 is irradiated with the X-ray 3. Almost simultaneously with the start of the X-ray 3 irradiation, the X-ray line sensor 5 is activated by the computer 12 (step S6), and detection of the X-ray 3 transmitted through the subject 6 is started. Note that the subject 6 continues to be transferred from the start end 16 of the conveyor 7 toward the start end 17 at a predetermined speed even during irradiation with the X-ray 3.

  In this way, a series of transmitted X-ray brightness value data transmitted through each part of the subject 6 over the entire test part 10 is obtained, and the position data x of the test part 10 and the corresponding brightness are obtained. Data (x, y) consisting of value data y is accumulated in the computer 12 as needed. Simultaneously with this data (x, y), an image 18 of transmitted X-rays obtained by the X-ray line sensor 5 is obtained (step S7). An example of the captured image 18 obtained in this way is shown in FIG.

  Next, in step S <b> 8, the subject 6 is carried out from the X-ray shielding box 9 toward the start end portion 17 of the conveyor 7, and it is confirmed that the subject 6 does not exist in the X-ray shielding box 9. When it is confirmed that the subject 6 does not exist in the X-ray shielding box 9, the acquisition of the captured image 18 and the acquisition of the data (x, y) are finished (Step S9), and the irradiation of the X-ray 3 and the X are simultaneously performed. The detection of the X-ray 3 by the line line sensor 5 is also ended (steps S10 and S11).

  Thereafter, in step S12, the acquired captured image 18 is processed. In this processing, the data (x, y) is made to correspond to the function y (x), each data is set to orthogonal xy coordinates with the axis of the position data x being horizontally and the axis of the luminance value data y being vertically. Is plotted, and a graph A corresponding to the captured image 18 is created. An example of this graph A is shown in FIG.

  Based on this result, the thickness of the test part is visualized and output as an image. However, in the process of visualizing the test portion thickness z, the function data y (x) may be subjected to a predetermined calculation process to associate the position x of the test portion 10 with the test portion thickness z. Good. This is made to correspond on the basis of the correlation between the luminance value y and the thickness to be detected z shown in Example 1 described later. That is, it is assumed that an analytical function z (y) is established between the thickness z to be examined and the luminance value y. Since the function z (y) = z (y (x)), the correspondence relationship between the position x of the test portion 10 and the test portion thickness z is established, and the vertical axis of the graph A in FIG. It is possible to convert the thickness to the test part thickness z.

  In steps S13 and S14, appropriate numerical processing or image processing is performed on the xz coordinate so that the remaining thickness z ′ of the test portion 10 and the length L of each groove 11 or between each groove 11 It is determined whether the pitch p is within an appropriate range. Such processing determination can of course be performed on the xy coordinates by z (y).

  For example, as shown in the first embodiment, the remaining thickness z ′ of the test portion 10 is determined by a linear function z = z (y) = ay + b between the luminance value y of the transmitted X-ray 3 and the test portion thickness z. If the above relationship holds, the following is performed. Specific values a and b are determined in advance depending on the material of the subject 6. The luminance value y of each test part 10 is sequentially substituted into ay + b and calculation is performed to calculate each test part thickness z. The thinner the thickness of the test portion, the larger the transmitted X-ray dose. Conversely, the greater the transmitted X-ray dose, the thinner the test portion 10 is. This is based on the experimental fact that the influence of the cross-sectional shape of the test part 10 on the transmitted X-ray dose is sufficiently smaller than the effect of the difference in the thickness of the test part 10 or the remaining thickness z ′. The location where the calculated value of the test portion thickness z is the maximum corresponds to the portion between the adjacent groove-like portions 11 in the test portion 10, and the location where the test portion thickness is appropriately small compared to it. Indicates the remaining thickness of the groove 11. When the remaining thickness z ′ is not sufficiently small or too small, for example, when the thickness z to be detected is out of the proper range, it is determined as defective and the inspection result of the remaining thickness to be tested Is output as NG (step S15).

  The determination of the length L of each groove-like part 11 is made by calculating the width of a concave part (referred to as a concave part) of the graph B (not shown) in the xz coordinate. Of course, this short length corresponds to the short length L of the groove-like portion 11 in the test portion 10, and if this length L is too short or too long, the test portion 10 NG is output as the inspection result of the length L of the groove-shaped portion 11 (step S15).

  Determination of the pitch p between each groove-shaped part 11 is made by calculating the width | variety between the adjacent recessed parts of the graph B in xz coordinate. The short interval corresponds to a small interval between adjacent groove portions 11 in the test portion 10, and when this interval is too small or too large, the groove portion 11 of the test portion 10. NG is output as the inspection result of the pitch p.

  In order to examine the correlation between the luminance value y of the test part and the test part thickness z of the part, the following experiment was performed. As shown in FIG. 5, four concave portions 19 having an oval planar shape are provided on the surface of a substantially homogeneous synthetic resin sheet, and the thickness of the bottom portion 20 is 0.3 mm, 0. The specimen 21 was formed by sequentially leaving a thickness of 4 mm, 0.5 mm, and 0.6 mm (see FIG. 6). The luminance value of each part of the specimen 21 was measured using the specimen thickness inspection apparatus 1 described in the above embodiment. A transmission image of the sample by X-ray 3 as shown in FIG. 5 is acquired, and an average value of luminance values y of the reference thickness portion of the bottom 20 is acquired from the data acquired as a result of the measurement. However, the average luminance value y ′ of the bottom portion 20 is within the range indicated by the hatched frame W in FIG. The obtained average luminance value y ′ and data of the thickness to be examined z of the part are plotted on the yz coordinates, and an approximate expression of the graph C is derived.

  FIG. 7 shows a graph C created based on the experimental results thus obtained. However, the experiment shown in the present example uses polypropylene having a pigment concentration of 2% as the synthetic resin material of the specimen 21. The approximate expression calculated based on the graph C shown in FIG. 7 is z = −0.0023y ′ + 7.045, where y ′ is the average luminance value of the test part 10 and z is the thickness of the test part at that part. . That is, using this approximate expression, if the average luminance value y ′ obtained by inspecting the actual subject 6 by the inspection apparatus 1 for the thickness of the test part is substituted into the approximate expression, the average remaining thickness z ′ is measured. it can.

It is a figure which shows the structure of the test | inspection apparatus of the to-be-tested part thickness which concerns on embodiment of this invention. FIG. 2 is a cross-sectional view of a subject to be inspected by the inspection apparatus of FIG. 1. It is a flowchart which shows an example of control and operation | movement of the inspection apparatus of FIG. (A) is a figure which shows the permeation | transmission image of the subject by the test | inspection apparatus of FIG. 1, (B) is a graph formed by plotting measurement data on an xy coordinate corresponding to a permeation | transmission image. It is a figure which shows the subject sample by the test | inspection apparatus of FIG. FIG. 6 is a cross-sectional view taken along the line AA of the subject sample shown in FIG. 5. FIG. 6 is a graph obtained by plotting the measured average luminance value y ′ of the subject sample of FIG. 5 and the data of the thickness of the portion to be examined z on the yz coordinates. It is a schematic diagram of a conventional inspection apparatus for the thickness of a test part. It is a perspective view of a subject. (A)-(F) are figures which show the cross section of the invisible process part of a test object. (A) And (B) is a graph of the relationship between the transmitted light amount regarding the conventional inspection apparatus, and the position of a to-be-tested part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Inspection part thickness inspection apparatus 2 X-ray source 3 X-ray 4 Slit 5 X-ray line sensor 6 Subject 7 Conveyor 8 Inspection space 9 X-ray shielding box 10 Test part 11 Groove part 12 Computer 13a Band 13b Band 14 Endless belt 15 Roller 16 Start portion 17 End portion 18 Captured image 19 Recessed portion 20 Bottom portion 21 Sample to be measured z 'Remaining thickness L Length of groove portion p Pitch W Diagonal frame

Claims (7)

  Irradiating the test part of the subject with X-rays, detecting the transmitted X-ray dose transmitted through the subject, and calculating the thickness of the test part from the measured value of the transmitted X-ray dose corresponding to each test part; A method for inspecting a thickness of a test part, comprising determining whether or not the thickness of the test part is within a desired range.   The inspection part thickness inspection method according to claim 1, wherein the measurement value of the transmitted X-ray dose uses the luminance of X-rays transmitted through the inspection part.   The measured value of the transmitted X-ray luminance is x, and the remaining thickness z of the test part is a linear function z = ax + b (where a is a coefficient specific to the substance that irradiates X-rays, and b is specific to the substance. The method for inspecting the thickness of the test part according to claim 2, wherein   A first step of irradiating the test portion of the subject with X-rays while transporting the subject, a second step of detecting X-rays transmitted through the test portion by an X-ray line sensor, and this detection A third step for obtaining the luminance of the X-ray dose transmitted through the test portion from the result, and calculating the thickness of the test portion based on the luminance of the X-ray dose, so that the thickness of the test portion is in a desired range And a fourth step of determining whether or not it is within the inspection portion thickness inspection method.   5. The method for inspecting a thickness of a test part according to claim 1, wherein the test part is a perforated groove-like part.   An X-ray source for irradiating the subject with X-rays and an X-ray disposed relative to the X-ray source with an examination space for irradiating the subject with X-rays X-ray luminance measuring apparatus for measuring the luminance of the apparatus, transport means for passing the subject through the examination space at a predetermined speed, the transport means, the X-ray brightness measuring apparatus, and the X-ray source And a control device that calculates the thickness of the test portion from the measured X-ray luminance and determines whether the thickness of the test portion is within a desired range. A device for inspecting the thickness of a portion to be examined. X is the luminance of the X-ray, and the remaining thickness z of the test part is a linear function z = ax + b (where a is a coefficient specific to the substance that irradiates X-rays, and b is a constant specific to the substance. 7. The inspection apparatus for the thickness of the test part according to claim 6, wherein

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