Patent Application
20090109287
The present invention relates to an inspecting method of an assembly, which is constructed with a plural number of parts, and in particular, it relates to an inspecting method for conducting an inspection of the condition of assembling, with using a projection drawing calculated, which is obtained from design data, and a projection image of an interior condition of the assembly, which is obtained by photographing. Further, it relates to an inspecting system of applying this method therein.
In general, an industrial product is an assembly made up with a plural number of parts thereof. For inspection of such the product, it is necessary to inspect the condition of assembling (for example, the degree of parallelism, and/or concentricity, etc.), in addition to an inspection of sizes for each part.
Conventionally, for the purpose of inspecting the condition of interior assembling, an X-ray projection apparatus is well applied. Within the X-ray projection apparatus, X-rays are irradiated upon an assembly, so as to detect that penetrating therethrough by a camera, and thereby obtaining the projection image thereof. The X-rays are attenuated in intensity or strength thereof, when penetrating through a substance, depending upon an attenuation factor and a penetration length (i.e., a distance which the X-rays advance in the substance), both of which are specific for that material. Accordingly, it is possible to know the position for each part within an inside of the assembly with an aid of the projection image.
Also, it can be considered to apply an X-ray CT (Computed Tomography) apparatus, as other method for the above. This X-ray CT apparatus, while obtaining the projection images through irradiation of the X-rays in a large number of directions surrounding the assembly, obtains a reconstructed image (i.e., the cross-section view) from an aggregate of a large number of projection images. Actually, the projection images, on which one-dimensional Fourier transformation is conducted in each direction, are composed so as to produce a two-dimensional Fourier transformation image, and on this is conducted inverse Fourier transformation, thereby obtaining the reconstructed image.
For example, in the following Patent Document 1 is disclosed a method for inspecting defects on wiring patterns and defects in through holes, irradiating the X-rays on one surface of a print circuit board to be inspected, so as to detect the X-rays penetrating through to the opposite surface for imaging, and to compare the image obtained with size data of the wiring patterns and data of the through holes and the hole diameters thereof, which are given in advance.
Also, in the following Patent Document 2 is disclosed an inspecting method for conducting an inspection of a multi-layer substrate, by producing an image of three-dimensional structures of an inside of that substrate, with using a photographing result by using the X-ray CT apparatus in the direction perpendicular to a multi-layered substrate, and the designed values in the horizontal direction thereof.
[Patent Document 1] Japanese Patent Laying-Open No. Hei 07-235773 (1995); and
[Patent Document 2] Japanese Patent Laying-Open No. Sho 60-161551 (1985).
However, with the technology disclosed in the Patent Document 1, there is a problem, though it is possible to identify the position in the direction perpendicular to propagating direction of the X-rays irradiated, but it is impossible to identify the position in the propagating direction of the X-rays.
Also, with the technology described in the Patent Document 2, because of obtaining a large number (for example, 1,200 pieces) of projection images for one (1) piece of an assembly, it takes a time for photographing, and the calculation for reconstruction also needs a time, because it repeats the Fourier transformation; i.e., it needs one (1) hour, or more or less, in total for one (1) piece. Also, there are sometimes cases where a virtual image appears, which is called “artifact” specific to the X-ray CT apparatus, and this sometimes brings about an obstacle or difficulty. For this method, because the three-dimensional structures of the assembly are clear, it is possible to avoid the condition that the position cannot be identified in the propagating direction of the X-rays, as was mentioned above. However, it takes the time too long, and therefore it is impossible to apply this in the inspection for the products of mass-production.
According to the present invention, by taking the drawbacks mentioned above into the consideration thereof, an object thereof is to provide an inspecting method for inspecting the interior condition of and assembly, i.e., a target to be inspected, by obtaining the three-dimensional position relationships among the parts building up the assembly, in a short time. Further, another object thereof is to provide an inspecting system for the assembly with applying the inspecting method therein.
For accomplishing the object mentioned above, according to the present invention, there is provided an inspecting method of an assembly, for inspecting said assembly, being constructed with a plural number of parts, upon basis of a calculated projection view of showing an interior condition of parts of said assembly, which is obtained through calculation of design data of the assembly, and a projection image for showing the interior condition of parts of said assembly, which is obtained by a photographing apparatus after assembling said assembly, comprising the following steps of: a step for calculating brightness in vicinity of boundaries, which are obtained when photographing the part to be extracted in plural numbers of directions, from said design data, for each direction; a step for determining sensitivity of said photographing apparatus upon basis of said brightness, so that the projection image becomes clear in the vicinity of said boundaries; a step for obtaining the projection images in the plural number of directions for said assembly, by said photographing apparatus; a step for conducting video processing with converting said projection image into an electric signal, as an actual projection view; and a step for determining success or failure of said assembly, depending upon said part presented on said actual projection lies or not within a tolerable region of said part, which is presented by said calculated projection view.
In this manner, since the brightness in the vicinity of boundaries of the part to be extracted can be calculated in each direction for photographing, thereby to determine the sensitivity of the photographing apparatus, as well as, to conduct the photographing in plural numbers of directions, therefore it is possible to provide the inspecting method of an assembly, for conducting an inspection of an interior condition, in short time, within the assembly, i.e., a target to be inspected.
Also, it is possible to provide the inspecting apparatus, applying therein the inspecting method of the assembly mentioned above.
According to the present invention mentioned above, since the three-dimensional position relationship can be known, in shot time, for each of the parts building up the assembly, therefore it is possible to provide an inspecting method of an assembly for conducting an inspection of success or failure of the assembly, with high efficiency.
Further, it is also possible to provide an inspecting system of an assembly, by applying the inspecting method mentioned above therein.
Those and other objects, features and advantages of the present invention will become more readily apparent from the following detailed description when taken in conjunction with the accompanying drawings wherein:
Hereinafter, embodiments according to the present invention will be fully explained by referring to the attached drawings.
However, the design data mentioned above includes, for example, three-dimensional coordinates for indicating the position of each part within the assembly, and sizes and angles, etc., for identifying the each part.
From the actual projection views 203 and 204 in both directions, it is possible to obtain the differences ΔX and ΔY between the calculated projection view and the actual projection view, and with this, the position relationship of the interior part 202 becomes clear with respect to the exterior part 201. Though the mentioned above is about the difference of the actual projection view from the design data obtained at the arbitrary position in the Z-axis direction, but by conducting this at all of the positions in the Z-axis direction, it is possible to obtain the three-dimensional position relationship of the interior part with respect to the exterior part, such as, an inclination of a center axis of the interior part 202, etc. With this, an inspection can be made on the condition of the assembly.
In more details, for determination on success or failure of the assembly, the following two (2) ways can be considered. One is a method, as is shown in
The other one is a method, as shown in
For inspecting the condition of an interior of the assembly, it is necessary to know the condition of arrangement, correctively, of the respective parts building up the assembly, from the actual projection view obtained. However, depending upon the condition of arrangement of the parts within an inside of the assembly, there are sometimes cases where a boundary lines between the parts has width, so that it becomes dim or unclear.
Then, according to the present inspecting method, the brightness of the calculated projection view and the actual projection view are presented as an aggregation of dots of 16 bits (i.e., 0 to 65,535), and a region of brightness is calculated from the design data, in advance, in the vicinity of boundaries to be extracted in plural numbers of directions, thereby determining a sensitivity of the camera corresponding to the brightness calculated, so as to enable the photographing.
Explanation will be made in more details by referring to
Next, explanation will be given on an inspecting system for an assembly for achieving such the inspection as was mentioned above.
The data editor/processor portion 2 stores the design data, such as, the coordinates for indicating the portion of apart within the assembly, and sizes and an angle of the part, etc., and further, it produces the calculated projection view with using this design data.
The brightness calculator portion 3, as was mentioned previously, because the brightness differs from depending on the condition of disposing the part, calculates out the brightness in the vicinity of boundary of the part to be extracted, upon basis of the calculated projection view. Upon basis of the brightness, which calculated within the brightness calculator portion 3, the sensitivity setup portion 4 converts it into a sensitivity corresponding to the camera of the image pickup apparatus 5. Herein, determination of the sensitivity can be made for each photographing, differing from the X-ray CT apparatus. The image pickup apparatus 5 may be an X-rays image pickup apparatus, which is made up with an X-rays generating apparatus and a camera.
The video processor portion 6 converts the actual projection view, which is picked up by the image pickup apparatus 5 mentioned above, into the electric signals, such as, digital data, which can be easily treated by video processing, and the actual projection view is produced by conducting the video processing thereon.
The determination portion 8 has a function of determining the success or failure of the assembly, depending on whether the position of the part of the assembly on the actual projection view lies or not within the tolerable region of the position of the part on the calculated projection view, which is obtained from the data editor/processor portion 2, and a function of determining the success or failure of the assembly, depending on whether the difference calculated within the difference calculator portion lies or not within the tolerable value of the difference, which is obtained from the data editor/processor portion 2.
In this manner, the three-dimensional position relationship can be obtained among the parts building up the assembly, in short time, and therefore it is possible to inspect of the interior condition of the assembly, i.e., an object to be inspected.
The mentioned above is the explanation of the case of using two (2) sets of the photographing apparatuses, each being made up with the X-ray generator apparatus and the camera, however in
While adding the cutting depth of the part 902 at a predetermined rotation speed of the rotation shaft 901 and the position of the bite 903 as the design data, upon this design data is obtained the calculated projection view, in advance, and this is compared with the actual projection view, which is obtained through the photographing, thereby it is possible to obtain a difference between the calculated position of a tip of the bite 903 and the actual position thereof. Correction of the position of holding the bite, with using this difference, enables the machining on the inside of the hole of cylinder-type, which cannot be seen from an outside thereof, at high accuracy.
In this manner, it is possible to obtain the three-dimensional position of an attended portion of the part, upon which attention is paid, almost in a real-time manner. For this reason, this method can be applied into the machining process with using the lathe or a fraise (milling cutter), in particular, as a monitor for the position of the bite tip, in case where the bite tip cannot be seen from an outside since it is under the cutting the inside of the part.
Explanation will be made on an embodiment 3 of the present invention. The embodiment 3 relates to an assembly built up with “N” pieces of parts, as the target to be inspected, and wherein the sizes and a mutual position relationship of each part are uses as the design data. From this design data are obtained the calculated projection views in two (2) directions, in advance. By comparing the actual projection views in two directions, which are obtained in the similar manner, with the calculated projection views, respectively, as was mentioned above, it is possible to obtain the differences between the actual position and the direction thereof and the design data, for each of “N” pieces of the parts, respectively.
By correcting the design data with this difference, and also producing a calculation mesh for use of a fluid-, heat- or structure-calculation with using this data, it is possible to conduct calculation simulation for reproducing an actual position relationship of each part, with fidelity. The similar thing can be achieved with using the X-ray CT apparatus, but with this, there can be obtained the following advantages. Thus, there is no generation of the specific “artifact”, which can be seen on the X-ray CT apparatus, the calculation mesh can be produced in time much shorter than the X-ray CT apparatus, and further, the X-ray photographing apparatus can be achieved at the cost cheaper than the X-ray CT apparatus.
However, in the present embodiment is applied the X-ray for penetration of the interior configuration of the assembly. But other than the X-ray, it is also possible to apply MRI (Magnetic Resonance Imaging) therein.
While we have shown and described several embodiments in accordance with our invention, it should be understood that disclosed embodiments are susceptible of changes and modifications without departing from the scope of the invention. Therefore, we do not intend to be bound by the details shown and described herein but intend to cover all such changes and modifications that fall within the ambit of the appended claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2007-283817 | Oct 2007 | JP | national |
