JP2010271045A - Visual examination device of ceramics sphere - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent charging of static electricity, and to detect flaws, such as, color unevenness which are specific to a ceramics spheres that are difficult to detect by a conventional device, especially in a visual examination device of the ceramics sphere. <P>SOLUTION: In a device for determining the presence of the flaw of the ceramics sphere 1 by immersing the ceramics sphere in oil, irradiating the surface of the ceramics sphere, which is rotated in the oil in a meridian-like state by a rotary device, with a light by an illumination means 6 to photograph the entire surface of the ceramics sphere by a photographing means 7 and processing the photographed surface image of the ceramics sphere to determine the presence of the flaws of the ceramics sphere, the illumination means 6 is especially constituted as an illumination means, capable of irradiating the ceramics sphere with light so as to become a bright field of view and a dark field of view. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a visual inspection apparatus for determining the presence or absence of defects in spheres used in bearings, ball valves, and the like, particularly ceramic spheres.

  Conventionally, a surface inspection apparatus for a sphere, such as a steel ball, generally inspects a sphere in the air. However, inspection in the air has the advantage that the sphere is easy to handle, but if the sphere surface is not completely degreased by cleaning, the oil will be stained and not only erroneously determined as defective, but also the oil will be sent to the inspection section. Accumulated in the passage of the sphere until it arrives, and further adheres to the sphere, causing it to be erroneously determined as defective. Further, there is a problem that rusting is a concern when the sphere is easily rusted when left for a long time in a degreased state.

Therefore, the present applicant has no problem of the above-mentioned oil stains, and as a device that can achieve the appearance inspection of the sphere without rusting even with a metal that easily rusts without the need for degreasing, It is found that a defect inspection is performed by immersing an inspection ball, and as shown in FIG. 7, the steel ball 11 to be inspected is immersed and held in oil, and light is applied to the steel ball 11 from a light source 12. A device has been proposed in which reflected light from a steel ball is received by the light receiving element 13 to electrically convert the amount of received light, and the determination unit 14 determines the presence or absence of a defect based on the amount of change in the electrical signal. (For example, see Patent Document 1)
However, in the optical appearance inspection apparatus that determines the presence or absence of defects based on the amount of change in the electrical signal as described above, it is suitable for a steel ball having a mirror-finished surface used for a general bearing. However, in recent years, for ceramic spheres that require higher speed and higher efficiency and require lighter weight, the surface of the ceramic sphere is grayish white or black. Since the amount of reflected light from the head is greatly reduced, it cannot be said that it is an effective inspection method.

  Therefore, it was considered to increase the amount of light reflected from the sphere by increasing the amount of light from the light source, but in that case, the reflected light from other than the sphere also entered the light receiving element, and the signal change at the good spherical surface and the defective part occurred. There is a drawback that it becomes smaller and it becomes difficult to detect minute defects. In particular, in the case of ceramic spheres, microscopic defects such as irregularities and voids due to segregation of foreign matter and sintering aid existing in the extreme surface layer of the defects, the change in the amount of reflected light from the good spherical surface at that part. Since it is very small, there is a problem that it is difficult to detect with an optical visual inspection apparatus.

  On the other hand, inspection with the naked eye using a microscope is also conceivable, but there is a problem that the increase in cost is unavoidable due to the burden of labor costs and that it is difficult to economically respond to the future increase in demand for ceramic balls. is there. Also, unlike steel balls, ceramic balls tend to be charged with static electricity when rubbed in the air, and there is a so-called misjudgment problem that adsorbs small dust in the air and regards this dust as a defect.

  Therefore, the present applicant has dealt with the actual situation as described above, and has advanced the improvement particularly focusing on the appearance inspection of the ceramic sphere, and has performed a predetermined process on the image photographed by the digital camera while holding the sphere in oil. We have developed and proposed a device that prevents electrostatic charges on the ceramic spheres by applying, and makes it possible to detect minute defects that are difficult to detect with the optical inspection device described above and defects peculiar to ceramics. (For example, see Patent Document 2)

JP 2002-277226 A JP 2008-51619 A

  However, when the above device was tried for actual use after that, it was better than the previous device for fine defects with irregularities on the surface such as burrs, cracks, foreign matter exposed on the surface of the sphere, or exposed fine defects. However, it was found that sufficient detection was still not possible for defects specific to ceramic spheres, such as foreign matter existing in the extreme surface layer of ceramic spheres and color unevenness and voids due to segregation of sintering aids. . Therefore, the present inventor has further studied the improvement, and as a result, has found that it is preferable to irradiate the ceramic sphere to be inspected with a bright field and a dark field.

  The present invention is based on the knowledge of irradiating light to the bright field and dark field, and by this, segregation of foreign matter and sintering aid present in the surface layer portion of the ceramic sphere that could not be sufficiently detected before. An object of the present invention is to make it possible to detect defects peculiar to ceramics such as uneven color and voids, and to detect defects on the surface of the ceramic sphere more reliably.

That is, the feature of the present invention that meets the above object is that the surface of ceramic spheres such as silicon nitride (Si ₃ N ₄ ), zirconia (ZrO ₂ ), alumina (Al ₂ O ₃ ), silicon carbide (SiC), etc. As an appearance inspection device for inspecting defects, a ceramic sphere to be inspected is immersed in oil, rotated in a meridian shape by a rotating device in oil, light is applied to the ceramic sphere by illumination means, and the surface of the sphere is exposed by imaging means. In a configuration in which a photograph is taken and an image output from the photographing means is subjected to predetermined processing by an image processing means to determine the presence / absence of a defect in the ceramic sphere, particularly the ceramic sphere to be inspected for the illumination means. In addition, the illumination means irradiates light so that a bright field and a dark field are obtained.

  In the above configuration, as a specific aspect of the illumination means, for example, by providing a mechanical stage so that the ceramic sphere can be irradiated with light that becomes bright field and dark field, the light source can be easily and accurately front and rear, left, right, top and bottom. It can be moved and rotated.

  Here, in the inspection in the bright field, for example, pits and cracks, irregularities on the surface of the sphere such as foreign matters exposed on the surface of the sphere, or exposed minute defects can be detected, and in the inspection in the dark field, for example, It is possible to detect defects peculiar to ceramic spheres, such as color unevenness and voids due to segregation of foreign matter and sintering aid existing in the extreme surface layer portion of the ceramic sphere. In addition, as a photographing means, an area camera or a line camera with a lens attached is used. These light source and the lens attached to the area camera or line camera can be arranged in oil, or can be arranged in the upper part of the oil surface. However, when placed on the upper surface of the oil surface, a transparent body such as glass or acrylic should be placed between the light source and the lens of the area camera or line camera and the ceramic ball to be inspected in order to eliminate disturbances in the captured image due to fluctuations in the oil surface. It is preferable to arrange.

  Thus, the light source as the illumination means and the lens attached to the area camera or line camera as the photographing means are arranged in the oil, or a part of the lens between the photographing means and the ceramic sphere is placed in the oil by placing it on the oil surface. Place an immersed transparent body and irradiate the ceramic sphere with light that becomes bright and dark fields directly from the light source or through the transparent body, and photograph the entire surface of the sphere directly or through the transparent body with an area camera or line camera This is an embodiment of the present invention.

  As described above, the present invention, unlike the optical type, detects defects on the sphere surface by processing the image of the sphere surface photographed by the area camera or line camera using light that becomes a bright field and a dark field as a light source. It is possible to detect minute defects that are difficult to detect with an optical inspection device and defects such as color irregularities and holes unique to ceramic spheres. This has the effect of reliably detecting defects in form.

  Moreover, since the entire surface of the sphere is scanned in a meridian manner by the rotating device as described above, it is possible to inspect the entire surface of the sphere, and by installing the rotating device in the oil, it is possible to inspect the oil before the inspection. The step of degreasing and drying the sphere can also be omitted. In particular, ceramic spheres are easily charged with static electricity, and there is a risk of misjudgment due to the adhesion of dust in the air, but there is also an effect that can be suppressed by inspecting in oil.

It is the figure which showed roughly the principal part of the inspection apparatus of this invention. It is the figure which showed roughly the principal part of other embodiment of the test | inspection apparatus of this invention. It is the figure which showed bright field illumination schematically. It is the figure which showed dark field illumination schematically. It is a photograph figure which shows the example of a detection of the color nonuniformity in the bright field in FIG. It is a photograph figure which shows the example of a detection of the color nonuniformity in the dark field in FIG. It is the figure which showed the principal part of the conventional inspection apparatus roughly.

  Specific embodiments of the present invention will be described below with reference to the accompanying drawings. 1 and 2 are diagrams schematically showing an example of an appearance inspection apparatus according to the present invention. In the figure, reference numeral 1 denotes a ceramic sphere that is a sphere to be inspected according to the present invention. Reference numeral 1 denotes a drive roller 2, a support roller 3, and a control roller 4 that are fixed in place while being immersed in oil. And the ceramic ball | bowl 1 rotates by rotating the drive roller 2, and, thereby, the control roller 4 also rotates. An eccentric helical gear 5 is attached to the control roller 4, and the eccentric gear 5 gives a twist to the ceramic sphere 1 to be inspected, and the ceramic sphere 1 rotates in a meridian shape. This basic configuration is as described in detail in the above-mentioned prior document related to the applicant's proposal.

  However, in the present invention, as shown in FIG. 7, light from the light source 12 is applied to the inspection target sphere 11, the reflected light is received by the light receiving element 13, and the received light amount is electrically converted, and the determination unit 14 uses the change amount of the electric signal. Unlike the determination of the presence or absence of defects, the image was taken using a light source provided with a mechanism capable of emitting bright-field and dark-field light as illumination means and an area camera or line camera with a lens attached as photographing means. A predetermined process is performed on the image by an image processing means to determine the presence or absence of defects on the entire surface of the sphere.

  That is, in the present invention, as shown in FIGS. 1 and 2, an area camera or a line camera 7 to which a lens 8 for photographing the entire surface of a sphere is attached is provided, and the ceramic sphere 1 to be inspected is put in oil. As shown in FIG. 3, a bright field in which most of the reflected light from the sphere is incident on an area camera or a line camera 7 to which a lens 8 as an imaging unit is attached, as shown in FIG. As shown in the figure, a light source whose position has been adjusted using a mechanical stage at a predetermined position that forms a dark field so that most of the reflected light from the sphere does not enter the area camera or line camera 7 to which the lens 8 as the imaging means is attached. 6 is irradiated with light and the surface of the sphere is photographed by the area camera or the line camera 7 and the photographed image is sent to the processing personal computer 9 for It is adapted to determine the presence or absence of a defect in the inspected ceramic spheres by performing a predetermined process which is set in advance for the image.

  Here, in the appearance inspection apparatus, the drive roller 2 that rotates the ceramic sphere 1 to be inspected, the control roller 4, and the support roller 3 that supports the sphere are immersed in oil for inspection in oil. It is possible to irradiate light that becomes bright and dark fields by being attached to a mechanical stage that can be moved up and down, left and right and back and forth in the vicinity of the ceramic sphere 1 to be inspected that is rotating in a meridian shape by a rotating device. Both the light source 6 and the lens 8 of the area camera or line camera 7 for photographing the surface of the sphere are arranged at predetermined positions in the oil, and the ceramic sphere 1 in the rotating oil is brightened from the light source 6. The entire surface of the sphere can be photographed by the area camera or the line camera 7 that is fixed to a predetermined position by irradiating light that becomes a visual field and a dark field. Going on. If there is a defect in the inspection target sphere, in the case of a bright field, light is scattered at the defective portion and does not enter the area camera or the line camera 7, and the luminance value decreases at the defective portion and is displayed in black. The captured image is processed according to preset determination conditions and determined as a defect.

  On the other hand, in the case of a dark field, the light scattered at the defective portion is incident on the area camera or the line camera 7, so that the luminance value increases at the defective portion and is displayed in white. Further, for example, in the case of color unevenness, it hardly appears in the bright field as seen in FIG. 5, but appears clearly in the dark field as seen in FIG. 6, and the difference between the two becomes clear.

  As described above, there is a difference in the image obtained by processing the captured image due to the difference between the bright field and the dark field, and defects that cannot be obtained in the bright field can be obtained in the dark field. And holes can be detected. Note that the lens 8 attached to the area camera or the line camera 7 can be easily dealt with by appropriately changing the lens magnification for the purpose of detecting finer defects.

  Although it is desirable that the lens 8 and the light source 6 of the area camera or line camera 7 are in oil as shown in FIG. 1, the lens 8 and the light source 6 of the area camera or line camera 7 are not necessarily in oil but are shown in FIG. You may make it arrange | position to an oil level upper part as shown. However, in this case, as shown in FIG. 2, in order to eliminate the influence of the fluctuation of the oil level, the transparent body 10 such as glass or acrylic is used for the lens 8 of the area camera or line camera 7 and the light source 6 and the ceramic sphere 1 to be inspected. It is necessary and effective to place a part of the oil in the middle.

  In the above description, the case of irradiating light that becomes a bright field and a dark field by changing the position of the light source that is an illuminating means is explained. However, as a light source, two structures for bright field and dark field are provided. Also good. In that case, it is desirable to turn off the illumination on the side not inspected or prevent the light from reaching the ceramic sphere to be inspected. In particular, the rotation device described above is installed in oil, enabling inspection in oil. This eliminates the steps of cleaning, degreasing, and drying the ball before the inspection. Unlike a sphere, it is easy to be charged with static electricity, and in the air, dust and the like are likely to adhere to it. In this case, as the oil to be used, it is desirable to use oil that has been filtered through a microfilter and from which fine objects have been removed.

  As described above, the present invention irradiates a ceramic sphere, which is a sphere to be inspected, with light that is a bright field and a dark field, shoots the surface of the sphere with an area camera or a line camera, and processes the captured image. Therefore, the present invention is extremely useful as a surface appearance inspection apparatus for ceramic spheres, which are expected to increase in demand in the future in various fields.

1: Ceramic ball 2: Drive roller 3: Support roller 4: Control roller 5: Eccentric helical gear 6: Light source 7: Area camera or line camera 8: Lens 9: PC for processing 10: Transparent body 11: Ball for inspection 12: Light source 13: Light receiving element 14: Determination unit

Claims (5)

A ceramic sphere visual inspection apparatus for inspecting surface defects of ceramic spheres such as silicon nitride (Si ₃ N ₄ ), zirconia (ZrO ₂ ), alumina (Al ₂ O ₃ ), silicon carbide (SiC), etc. An illuminating means for irradiating the surface of the ceramic sphere rotated in the meridian with the rotating device, and the ceramic sphere In an inspection apparatus that includes an imaging unit that images a surface and an image processing unit that processes an image captured by the imaging unit, and determines whether there is a defect in a ceramic sphere by processing an image of the captured sphere surface The ceramic sphere is characterized in that the illuminating means is an illuminating means for irradiating the ceramic sphere to be inspected with a bright field and a dark field. Visual inspection apparatus.   The appearance inspection apparatus for a ceramic sphere according to claim 1, further comprising a mechanism capable of changing to a position capable of irradiating light so that a light source as an illumination means has a bright field and a dark field.   3. The ceramic ball appearance inspection apparatus according to claim 1, wherein the photographing means comprises an area camera or a line camera to which a lens is attached.   A light source that is an illumination means and a lens attached to an area camera or line camera that is an imaging means are arranged in oil, and the ceramic spheres to be inspected in oil are irradiated with light that becomes bright and dark fields from the light source, 4. The ceramic ball appearance inspection apparatus according to claim 1, wherein the entire surface of the sphere is photographed by an area camera or a line camera.   A light source as an illuminating means and a lens attached to an area camera or line camera as a photographing means are arranged on the upper surface of the oil surface, and a part of the lens is immersed in oil between the photographing means and a ceramic sphere as a sphere to be inspected. Claims 1, 2, or 3 wherein a body is disposed, light that is a bright field and a dark field is irradiated from a light source through a transparent body, and the entire surface of the sphere is photographed by an area camera or a line camera through the transparent body The ceramic ball appearance inspection apparatus described.