JP2021156739A - Vehicle body x-ray ct imaging method and x-ray ct imaging device - Google Patents

Abstract

To provide a vehicle body X-ray CT imaging method and X-ray imaging device that enable a check of an inner state of a local portion such as a welding part of a vehicle body, joint part thereof or the like as a three-dimensional image.SOLUTION: A vehicle body X-ray CT imaging method is configured to: support a detector 14 with the detector plugged inside an imaging portion of a vehicle body 10; irradiate an X-ray toward the imaging portion, as rotating an X-ray source 15 arranged outside the imaging portion of the vehicle body 10; and re-configure an obtained image of the imaging portion to acquire a three-dimensional image of the imaging portion. It is preferable to use a robot arm as detector supporting means and X-ray source supporting means.SELECTED DRAWING: Figure 1

Description

The present invention relates to an X-ray CT imaging method and an X-ray CT imaging device for an automobile body.

There are many welds and joints in the automobile body, and there is a technology that can confirm the adhesion between plates inside them, the crimping condition of rivets, the spread status of adhesive, the welding status of spot welding, etc. as a three-dimensional image. It has been demanded. The internal condition of welded parts and joints cannot be grasped by visual inspection. Therefore, it is conceivable to acquire an internal three-dimensional image by using X-ray CT technology.

As shown in Patent Documents 1 and 2, ordinary X-ray CT imaging is performed by a method in which an X-ray source and a detector are faced to each other and fixed, and a work placed between them is rotated 360 degrees. However, when the work becomes large like an automobile body, it is impossible to rotate it 360 degrees. Therefore, a technique for X-ray CT imaging of each part while the work is fixed is required.

Patent Document 3 describes a device that rotates a set of an X-ray source and a detector while the work is fixed. However, in order to perform a local inspection of welded parts and joints of an automobile body by this method, it is necessary to rotate the X-ray source or detector in a narrow space inside the body. Therefore, such a shooting method cannot be adopted either.

JP-A-2007-163254A Japanese Unexamined Patent Publication No. 2008-224692 Japanese Unexamined Patent Publication No. 2006-023187

Therefore, an object of the present invention is to solve the above-mentioned conventional problems, and to confirm the internal state of a local part such as a welded part or a joint part of the automobile body as a three-dimensional image X-ray CT of the automobile body. It is to provide an imaging method and an X-ray CT imaging apparatus.

In the X-ray CT imaging method of the automobile body of the present invention, which has been made to solve the above problems, a detector is inserted inside the imaging portion of the automobile body to support the X-ray, which is arranged outside the imaging portion of the automobile body. It is characterized in that X-rays are irradiated toward a imaging site while rotating a radiation source, and the obtained image of the imaging site is reconstructed to acquire a three-dimensional image of the imaging site.

The X-ray source is preferably rotated in a plane parallel to the screen of the detector, and the angle at which the X-ray source is rotated is preferably 180 degrees or more.

Further, the X-ray CT imaging device of the automobile body of the present invention, which has been made to solve the above problems, is supported by a detector supporting means for inserting and supporting the inside of the imaging portion of the automobile body and the detector supporting means. The detector, the X-ray source supporting means that supports and rotates the X-ray source outside the imaging part of the automobile body, and the X-ray source supporting means that is supported by the X-ray source supporting means and irradiates the X-ray toward the imaging part while rotating. It is characterized by having an X-ray source.

It is preferable that both the detector supporting means and the X-ray source supporting means are robot arms. Further, it is preferable that the X-ray source supporting means is rotated by utilizing the rotation of the sixth axis of the robot.

According to the present invention, since the detector is inserted and fixed inside the imaged portion of the automobile body and the X-ray source is rotated outside the imaged portion of the automobile body, the welded portion of the automobile body is provided as long as there is a space for inserting the detector. It is possible to confirm the internal situation of a local part such as a joint or a joint as a three-dimensional image.

Further, if the detector is supported by using the robot arm and the X-ray source is rotated by using the robot arm, the accuracy and practicality can be improved.

It is a principle explanatory drawing of the X-ray CT imaging method. It is explanatory drawing of the image taken by the detector. It is explanatory drawing of the Embodiment of the X-ray CT imaging method. It is explanatory drawing of the state which the rotation angle of an X-ray source is limited. It is explanatory drawing of the image taken by the detector and the reconstructed image. It is explanatory drawing which shows the embodiment of the X-ray CT imaging apparatus. It is explanatory drawing of the positional relationship between an X-ray source and a detector. It is explanatory drawing of another embodiment. It is explanatory drawing of screen alignment of a master image and a photographed image. It is a figure which shows the criterion of a good or bad judgment. It is a drawing of the rivet joint part.

FIG. 1 is an explanatory diagram of the principle of the X-ray CT imaging method of the present invention. Reference numeral 10 denotes an automobile body, and in this figure, a joint portion 13 in which the steel plate 11 and the resin member 12 are bonded with an adhesive is shown as a photographing portion. Reference numeral 14 denotes a detector inserted inside the imaging portion, which is supported by, for example, a robot arm, as will be described later, and is fixed to the automobile body 10 so as not to move.

Reference numeral 15 denotes an X-ray source arranged outside the imaging portion of the automobile body 10. The X-ray source 15 irradiates X-rays toward the joint portion 13 which is an imaging portion while rotating as shown in the drawing, and performs X-ray CT imaging. The rotation center axis 16 of the X-ray source 15 is preferably perpendicular to the screen 17 of the detector 14, in other words, the X-ray source 15 is preferably rotated in a plane parallel to the screen 17 of the detector 14. .. It is preferable that the rotation center axis 16 coincides with the joint portion 13 which is the imaging portion.

When X-ray CT imaging is performed in this way, as shown in FIG. 2, the image from 360 degrees of the joint portion 13 sandwiched between the steel plate 11 and the resin member 12 becomes a shape centered on the imaging center O of the detector 14. Be photographed. A technique for reconstructing a three-dimensional image of the object from X-ray CT images of the same object taken from various angles is known and can be carried out by using a commercially available program.

When the joint portion 13 is photographed, an image of a circular imaging range centered on the target joint center can be obtained. As will be described later, the content of the joint portion 13 of the joint portion 13 is a joining method such as an adhesive, spot welding, or rivet joining. This part can be inspected. From the captured image centered on the joint portion 13, it is determined whether the image is OK or NG. As a judgment method, a method of comparing and inspecting a normal captured image and an captured image of the product part to be inspected this time is often used. The case of the adhesive is shown in FIG. 9, which will be described later, as an example.

As shown in FIG. 3, the detector 14 has to be inserted into the narrow space inside the automobile body 10, but since the X-ray source 15 may be rotated in the space outside the automobile body 10, it is rotated 360 degrees. In many cases it can be done. However, as shown in FIG. 4, the imaging portion is close to the bent portion of the automobile body 10, and the X-ray source 15 may not be rotated 360 degrees due to the interference with the automobile body 10. The captured image in such a case is shown in FIG. 5, but if the angle at which the X-ray source 15 is rotated can be 180 degrees or more, it is possible to reconstruct the three-dimensional image of the object. be. However, if it is less than 180 degrees, the reconstructed three-dimensional image becomes unclear, so it is preferable to rotate it by at least 180 degrees.

FIG. 6 is an explanatory diagram showing an embodiment of the X-ray CT imaging apparatus of the present invention. In addition to the detector 14 and the X-ray source 15 described above, the X-ray CT imaging device includes a detector supporting means 20 that inserts and supports the detector 14 inside the imaging portion of the automobile body 10 and outside the imaging portion of the automobile body 10. It is provided with an X-ray source supporting means 21 that supports and rotates the X-ray source 15. Each of these can be designed and manufactured individually, but in practice it is preferable to use a robot arm as shown in the figure.

The robot arm of the first robot used as the detector supporting means 20 supports the detector 14 inside the imaging site, and the robot arm of the second robot used as the X-ray source supporting means 21 supports X-rays outside the imaging site. Rotate source 15. At this time, as shown in FIGS. 6 and 7, it is preferable that the center of the detector 14 and the center of the imaging portion coincide with the rotation center axis of the X-ray source 15.

The first robot and the second robot each have teaching coordinates, and are taught so as to have the positional relationship shown in FIG. The teaching coordinates can be taken out from the controller of the robot, and the radius of gyration r of the X-ray source 15 can be obtained from the mounting offset amount of the X-ray source 15. From the teaching coordinates, the A dimension (distance from the center of the detector 14 to the center of the imaging site) and the B dimension (distance from the center of the imaging site to the rotation center of the X-ray source 15) can also be known. The amount of deviation R from the center of the detector 14 to the projected image can be obtained. These values are input to the reconstruction program as parameters necessary for reconstructing the three-dimensional image of the object from the X-ray CT image.

Most of the robots currently used in the industrial world are 6-axis robots, and the 6th axis is used as the detector support means 20 and the X-ray source support means 21. Although each robot is taught so as to have the positional relationship shown in FIG. 6, its stopping accuracy is not high. Since the robot arm of the first robot used as the detector supporting means 20 only supports the detector 14, high position accuracy is not required, but the robot arm of the second robot used as the X-ray source supporting means 21. The position accuracy of is important.

However, since the rotation of the sixth axis is the rotation of only one axis, the rotation accuracy is sufficiently high. Therefore, even if the position accuracy of the 6th axis is not sufficient, the rotation of the X-ray source 15 by the 6th axis itself can be performed with high accuracy, which does not hinder the implementation of the present invention. No.

It is also possible to incline the central axis of the X-ray source 15 with respect to the rotation central axis of the X-ray source 15 as shown in FIG. In this case, the tilt angle is input to the program for reconstructing the three-dimensional image.

Next, the image alignment and the quality judgment will be described with reference to FIGS. 9 and 10. Here, an example of inspecting the shape of the adhesive at a certain joint portion by X-ray CT imaging is shown. The master image drawn on the left side of FIG. 9 shows the shape of the regular adhesive at the adhesive portion. On the other hand, in the photographed image drawn on the right side of FIG. 9, the shape and angle of the adhesive deviate from the master image. As shown in the lower part of FIG. 9, these images are superposed, and the coordinates are rotated and enlarged / reduced to obtain the image of FIG.

As shown by the broken line in FIG. 10, the MAX range and the MIN range of the adhesive are set on both sides of the contour line of the master image, and it is a good product if the actual image taken is within these ranges. However, as shown in the figure, if a part of the adhesive protrudes from the MAX range of the adhesive, or conversely does not reach the MIN range, it can be automatically determined as a defective product.

By performing X-ray CT imaging using a robot in this way, it is possible to perform automatic inspection of welded portions and joint portions of many automobile bodies 10. Since these are sites that have been difficult to inspect in the past, the practical value of the present invention is high.

In the above-described embodiment, the imaged portion is a joint portion, but it goes without saying that it can be applied to a rivet joint portion and a welded portion as shown in FIG. Internal cracks may also occur at the rivet joint as shown on the right side of FIG. 11, and according to the present invention, such internal defects can also be confirmed as a three-dimensional image.

As described above, according to the present invention, it is possible to accurately confirm the internal state of a local part such as a welded part or a joint part of an automobile body, which has been difficult to inspect in the past, as a three-dimensional image. , Can contribute to the improvement of the quality of the automobile body.

10 Automobile body 11 Steel plate 12 Resin member 13 Joint 14 Detector 15 X-ray source 16 Rotation center axis 17 Detector screen 20 Detector support means 21 X-ray source support means 21

Claims (6)

A detector is inserted inside the imaged part of the automobile body to support it, and X-rays are irradiated toward the imaged part while rotating the X-ray source located outside the imaged part of the automobile body. An X-ray CT imaging method for an automobile body, which comprises reconstructing an image to acquire a three-dimensional image of an imaged portion. The X-ray CT imaging method for an automobile body according to claim 1, wherein the X-ray source is rotated in a plane parallel to the screen of the detector. The X-ray CT imaging method for an automobile body according to claim 1 or 2, wherein the angle at which the X-ray source is rotated is 180 degrees or more. A detector supporting means that inserts a detector inside the imaged part of the automobile body to support it, a detector supported by this detector supporting means, and an X-ray source that supports and rotates the X-ray source outside the imaged part of the automobile body. An X-ray CT imaging device for an automobile body, characterized by comprising a support means and an X-ray source that is supported by the X-ray source support means and irradiates X-rays toward an imaging site while rotating. The X-ray CT imaging device for an automobile body according to claim 4, wherein both the detector supporting means and the X-ray source supporting means are robot arms. The X-ray CT imaging device for an automobile body according to claim 5, wherein the X-ray source supporting means is rotated by utilizing the rotation of the sixth axis of the six-axis robot.

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