JP2013142596A - Cylindrical inner surface detection optical system and cylindrical inner surface detector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform imaging all across a cylindrical inner surface robustly with respect to displacement of positioning of an optical system in the cylinder of a detector.SOLUTION: A cylindrical inner surface detection optical system includes: a light source 16; a beam splitter 20 for reflecting illumination light from the light source 16 in the cylinder so that it becomes coaxial light of the cylinder; a diaphragm part 26 for restricting aperture of the illumination light reflected by the beam splitter 20; a convex lens part 28A for collecting the illumination light restricted by the diaphragm part 26; a reflection mirror 28B with a convex surface for reflecting the illumination light collected by the convex lens part 28A across the cylindrical inner surface and reflecting the reflection light from the inner surface on an imaging device 24 for imaging the inside the cylinder; and an objective convex lens part 28C which is provided opposite to the inner surface and illuminates the illumination light reflected by the reflection mirror 28B on the inner surface, and collecting and receiving the reflection light from the inner surface.

Description

  The present invention relates to a cylindrical inner peripheral surface inspection optical system and a cylindrical inner peripheral surface inspection device.

  2. Description of the Related Art Conventionally, a cylindrical hole inspection device that detects results such as a cast hole, a flaw, and a burr on the inner surface of a hole is known (Patent Document 1). This cylindrical hole inspection apparatus includes an illuminating means for illuminating the inner surface of a cylindrical hole, a light guiding means for transmitting illumination light from the illuminating means, and an illumination irradiating means for irradiating illumination light from the weather guiding means into the hole. And the image reflection means, and the illumination angle irradiated from the illumination irradiation means and the incident angle of the image reflected on the inner surface of the hole and incident on the image reflection means are substantially regular reflections. A defect detection unit is provided from an image of the inner surface of the hole imaged by the imaging unit through the endoscope and the endoscope and the image transmission unit.

JP 2008-233715 A

  In the technique described in Patent Document 1, the illumination angle irradiated from the illumination irradiation unit and the incident angle of the image incident on the image reflection unit reflected by the inner surface of the hole are configured to be substantially regular reflection. There is a need.

  However, in the optical system described in Patent Document 1, it is difficult to insert an inspection probe having a reflection optical system at the tip into the cylinder to be inspected with high positioning accuracy, and the case is inserted with a misalignment or an inclination. There are many.

  At this time, in the optical system described in Patent Document 1, when the probe is inserted with a misalignment or inclination, the reflection direction on the inner wall surface of the cylinder is reflected in a direction deviated from the regular reflection optical system. However, even when the entire image is captured darkly and there is a defect such as a nest or a flaw in the portion, it is difficult to detect them.

  Further, in order to prevent misalignment and inclination, it is necessary to introduce an expensive positioning device and insert a probe under fine adjustment, so that the inspection speed cannot be increased.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide robust imaging against the displacement of the optical system positioning in the cylinder of the inspection apparatus and to image the inner peripheral surface of the cylinder. It is an object of the present invention to provide a cylindrical inner peripheral surface inspection optical system and a cylindrical inner peripheral surface inspection device that can be used.

  In order to achieve the above object, a cylindrical inner surface inspection optical system according to the present invention includes a light source for illuminating a cylinder and illumination light from the light source in the cylinder and the cylinder. A light guide part that guides light so as to be coaxial with the light, a diaphragm part for limiting an opening of illumination light guided by the light guide part, guided by the light guide part, and A convex lens part that condenses light to prevent diffusion of illumination light limited by the diaphragm part, and reflects the illumination light condensed by the convex lens part over the inner peripheral surface of the cylinder, and the inner peripheral surface A convex reflecting mirror that reflects the reflected light from the image to the imaging device that images the inside of the cylinder, and illumination light reflected by the reflecting mirror is applied to the inner peripheral surface and the reflected light from the inner peripheral surface Is provided opposite to the inner peripheral surface for collecting and receiving light. It is configured to include a thing convex portion.

  According to the present invention, the illumination light from the light source is irradiated over the inner peripheral surface of the cylinder via the light guide unit, the diaphragm unit, the convex lens unit, the convex reflecting mirror, and the objective convex lens unit. Then, the reflected light from the inner peripheral surface enters the imaging device via the objective convex lens portion, the convex reflecting mirror, the convex lens portion, and the aperture portion, and the inside of the cylinder is imaged by the imaging device.

  In this way, the convex reflecting mirror reflects the illumination light over the inner peripheral surface of the cylinder, and the objective convex lens unit collects and receives the reflected light from the inner peripheral surface. By reflecting the image inside the cylinder with the reflecting mirror to the imaging device, it is possible to form an image over the inner peripheral surface of the cylinder, which is robust against the displacement of the optical system positioning in the cylinder of the inspection device.

  The aperture portion can be adjusted in opening size. The angular spread of the inspection light projected on the inner peripheral surface of the inspection target cylinder is controlled by the size of the opening. Thereby, the sensitivity of the inspection can be adjusted.

  The cylindrical inner surface inspection optical system further includes an illumination convex lens portion that condenses light to prevent diffusion of illumination light from the light source, and the light guide portion is condensed by the illumination convex lens. Illumination light can be guided so as to be light within the cylinder and coaxial with the cylinder.

  The light guide unit transmits reflected light from the inner peripheral surface that is incident through the objective convex lens unit, the reflecting mirror, the convex lens unit, and the diaphragm unit, and the imaging device includes The reflected light from the inner peripheral surface that has passed through the light guide portion can be incident.

  A cylindrical inner peripheral surface inspection apparatus according to the present invention includes the above-described cylindrical inner peripheral surface inspection optical system, and an imaging device that captures an image representing the inside of the cylinder as an image for inspecting the inner peripheral surface of the cylinder. It is comprised including.

  According to the cylindrical inner peripheral surface inspection optical system and the cylindrical inner peripheral surface inspection device according to the present invention, the illumination light is reflected across the inner peripheral surface of the cylinder by the convex reflecting mirror, and by the objective convex lens unit. The reflected light from the inner peripheral surface is collected and received, and reflected to the imaging device that images the inside of the cylinder by the convex reflecting mirror, thereby preventing the optical system from being misaligned in the cylinder of the inspection device. Thus, there is an effect that the image can be imaged over the inner peripheral surface of the cylinder.

It is a schematic block diagram of the cylindrical inner peripheral surface inspection apparatus which concerns on embodiment of this invention. It is a figure for demonstrating coaxial epi-illumination. It is an example of a captured image, and is a diagram in which only a defect and its periphery are cut out. It is a figure which shows the optical path of the irradiation light and reflected light in a reflective mirror and an objective convex-lens part. (A) The figure which shows the optical path of irradiation light and reflected light in the case where there is no axial shift, (B) The figure which shows the optical path of irradiation light and reflected light in the case where axial deviation arises. (A), (B) It is a figure which shows the optical path of irradiated light and reflected light at the time of adjusting the magnitude | size of the opening of a diaphragm | throttle part. It is a figure which shows a defect model. It is a figure which shows a part of captured image obtained by simulation. It is a figure which shows the captured image in case there is no axis shift. It is a figure which shows the picked-up image in the case of accept | permitting axial deviation.

  Hereinafter, an example of an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of a cylindrical inner peripheral surface inspection apparatus according to an embodiment of the present invention. As shown in FIG. 1, the cylindrical inner peripheral surface inspection apparatus 10 according to the present embodiment includes a holder 14 that holds an inspection object 12 having a cylindrical hole, and a light source 16 that illuminates the inner surface of the cylindrical hole. The illumination convex lens 18 for condensing the illumination light from the light source 16 and the illumination light collected by the illumination convex lens 18 are guided to the cylindrical hole and the cylinder of the inspection object 12 A beam splitter 20 that reflects light so as to be coaxial with the hole, a camera convex lens 22 that condenses the light transmitted through the beam splitter 20, and the cylindrical hole of the inspection object 12 through the camera convex lens 22. An imaging device 24 for imaging, a diaphragm unit 26 for limiting the opening of the illumination light reflected by the beam splitter 20, and illumination light reflected by the beam splitter 20 and limited by the diaphragm unit 26 Condensing and irradiating illumination light over the inner peripheral surface of the cylindrical hole of the inspection object 12 and condensing the reflected light from the inner peripheral surface, and an image captured by the imaging device 24 And a computer 30 that performs image processing and detects defects. The beam splitter is an example of a light guide unit, and the light source 16, the illumination convex lens 18, the beam splitter 20, the diaphragm unit 26, and the compound lens 28 are examples of a cylindrical inner surface inspection optical system.

  The inspection object 12 has, for example, a cylindrical hole of φ14 mm and a depth of 25 mm, whose inner surface is a metal surface.

  Moreover, in the cylindrical inner peripheral surface inspection apparatus 10, the illumination light irradiated from the light source 16 is irradiated into the cylindrical hole so that the illumination is coaxial with the cylindrical hole. As a result, the illumination angle of the illumination light emitted from the light source 16 and the incident angle of the reflected light that is reflected by the inner peripheral surface of the cylindrical hole and enters the imaging device 24 are substantially regular reflections. Further, the cylindrical inner surface inspection device 10 is fixed to a moving mechanism (not shown) for inserting the compound lens 28 in the depth direction of the cylindrical hole, and the compound lens 28 is inspected by the moving mechanism. When it moves to the position of the cylindrical hole, it is inserted in the depth direction of the cylindrical hole.

  The diaphragm 26 is configured to be able to adjust the size of the opening of the illumination light. For example, the diaphragm portion 26 has a mechanism capable of adjusting the size of the opening manually.

  The compound lens 28 includes a convex lens-shaped convex lens portion 28A that condenses the illumination light reflected by the beam splitter 20 and limited by the diaphragm 26, and the illumination light condensed by the convex lens portion 28A. A convex curved reflecting mirror 28B that reflects the inner peripheral surface and reflects the reflected light from the inner peripheral surface to the imaging device 24, and the illumination light reflected by the reflecting mirror 28B is the inner peripheral surface of the cylindrical hole. And an objective convex lens portion 28C provided opposite to the inner peripheral surface of the cylindrical hole for condensing and receiving the reflected light from the inner peripheral surface. Regarding the convex curved reflector 28B, for example, a convex reflector is formed on the lower surface of the compound lens 28 (the surface opposite to the convex lens portion 28A).

  Next, operation | movement of the cylindrical inner peripheral surface inspection apparatus 10 is demonstrated. When the inspection object 12 is held by the holder 14 and positioned at the specified position, the cylindrical inner peripheral surface inspection apparatus 10 is moved by the moving mechanism so that the compound lens 28 is inserted into the cylindrical hole of the inspection object 12. Move.

  And the illumination light irradiated from the light source 16 passes through the convex lens 18 for illumination, the beam splitter 20, the diaphragm 26, the convex lens portion 28A, the reflecting mirror 28B, and the objective convex lens portion 28C, in the cylindrical hole of the inspection object 12. Irradiated over the inner peripheral surface. Then, the illumination light from the light source 16 is reflected on the inner peripheral surface of the cylindrical hole of the inspection object 12, and is incident on and reflected by the reflecting mirror 28B via the objective convex lens portion 28C, thereby forming the convex lens portion 28A and the diaphragm portion. 26, the beam splitter 20, and the camera convex lens 22, and enters the imaging device 24, and the imaging device 24 images the inside of the cylindrical hole of the inspection object. Further, the image is taken in a wide field of view over the inner peripheral surface of the cylindrical hole by the reflecting mirror 28B on the convex surface.

  At this time, if there is a defect portion A such as a natural nest, a flaw or a dent on the inner surface of the cylindrical hole, the specularly reflected light is scattered by the defect portion A as shown in FIG. As a result, as shown in FIG. 3, the image pickup device 24 picks up an image as a dark portion (background light).

  The computer 30 detects a defect by cutting out a defect candidate from light and dark from an image captured by the imaging device 24 and determining whether or not it is a defect.

  Further, the reflected light of the inner peripheral surface, which is slightly inclined from the perpendicular to the inner peripheral surface of the cylindrical hole of the inspection object 12, is collected by the objective convex lens portion 28C, and is directed to the imaging device 24 via the reflecting mirror 28B. To. As a result, not only the light perpendicular to the inner peripheral surface of the cylindrical hole of the inspection object 12 (see FIG. 5A) but also the inner periphery of the cylindrical hole of the inspection object 12 as shown in FIG. Light incident with a slight inclination from the direction perpendicular to the surface can also be imaged on the imaging surface of the imaging device 24. Therefore, even if the cylindrical inner peripheral surface inspection device 10 is slightly inclined with respect to the axis of the cylindrical hole of the inspection object 12, the reflected light on the inner peripheral surface of the cylindrical hole of the inspection object 12 is reflected. To the imaging device 24 via the reflecting mirror 28B.

  Also, as shown in FIGS. 6A and 6B, by changing the size of the aperture of the aperture 26, the diffused reflected light on the inner peripheral surface of the cylindrical hole of the inspection object 12 by the aperture aperture. The degree can be controlled. Here, since the degree of diffusion of the reflected light on the inner peripheral surface of the cylindrical hole corresponds to the degree of the defect (dent) to be detected, the detection sensitivity is controlled by adjusting the size of the aperture of the diaphragm portion 26. Can do.

  Next, a description will be given of an optical simulation that simulates the cylindrical inner peripheral surface inspection optical system according to the present embodiment, and results of experiments performed by creating experimental samples using the cylindrical inner peripheral surface inspection device.

  First, as shown in FIG. 7, the inner periphery of the cylindrical hole is illuminated by coaxial illumination for a model in which minute defects having a diameter of 0.2 mm and a border angle of 2.5 degrees are arranged at equal intervals on the inner peripheral surface of the cylindrical hole. A simulation of imaging the surface was performed. FIG. 8 shows a lower left portion obtained by dividing the captured image into four parts. Between the two circumferences is a circumferential inner surface portion to be observed. As shown in FIG. 8 described above, it was found that minute defects were captured by the captured image.

  In addition, when there is a recess on the inner peripheral surface of the cylindrical object to be inspected as shown in FIG. 9, an axis deviation within ± 0.1 mm (within ± 0.5 degrees) is allowed, and the captured image Acquired. FIG. 10 shows the obtained captured image. As shown in FIG. 10, it was found that dust and holes on the inner peripheral surface of the cylinder can be correctly detected even if an axial deviation within ± 0.1 mm occurs.

  As described above, according to the cylindrical inner peripheral surface inspection apparatus according to the embodiment of the present invention, the convex light reflecting mirror reflects the illumination light over the inner peripheral surface of the cylinder and the objective convex lens portion. The optical system positioning in the cylinder of the inspection device is shifted by condensing and receiving the reflected light from the inner peripheral surface and reflecting it to the imaging device that images the inside of the cylinder by the convex curved reflector. On the other hand, an image representing the entire circumference of the inner circumferential surface of the cylinder can be taken.

  By capturing an image over the inner peripheral surface of the cylinder at once with the convex-shaped reflecting mirror, the inner surface of the cylinder can be imaged in the circumferential direction and further in the depth direction with a single imaging.

  By adopting an optical system that captures reflected light by irradiating perpendicularly to the cylindrical inner wall surface, it is possible to capture the change in the inclination of the inner wall surface due to scratches and dents as a change in light intensity with high sensitivity. For example, it is possible to detect with high sensitivity scratches or dents having an inclination of 2.5 degrees or more and a size of 0.2 mm or more in the inner wall surface of the cylinder.

  Moreover, the influence of the inclination by position shift is reduced by condensing light with the objective convex lens part. As a result, the optical system positioning in the cylinder of the inspection apparatus is robust, and, for example, even if an inclination at the time of insertion occurs about 0.5 degrees, a scratch / dent is imaged with good S / N as an image. be able to.

  Moreover, the detection sensitivity of a flaw / dent can be adjusted by adjusting the size of the aperture of the diaphragm.

  In the above embodiment, the case where the diaphragm unit is configured to be able to adjust the size of the opening of the illumination light has been described as an example. However, the present invention is not limited to this, and the diaphragm unit can be replaced. You may comprise. In this case, the aperture size of the illumination light can be adjusted by using the apertures having different aperture sizes.

  Further, the case where a compound lens is used has been described as an example. However, the present invention is not limited to this, and a convex-convex convex lens portion, a convex curved reflector, and an objective convex lens portion may be provided separately. .

  Moreover, although the case where the convex-curved reflector is used as the reflector of the compound lens has been described as an example, the invention is not limited to this. For example, a convex surface that reflects illumination light over the inner peripheral surface of the cylinder A reflector (for example, a cone) may be used.

  Further, the case where the illumination light from the light source is guided into the cylinder by using the beam splitter has been described as an example, but the present invention is not limited to this, and the light source from the light source by using a light guiding means other than the beam splitter is used. The illumination light may be guided into the cylinder.

DESCRIPTION OF SYMBOLS 10 Cylindrical inner surface inspection apparatus 12 Inspection object 16 Light source 18 Illumination convex lens 20 Beam splitter 22 Camera convex lens 24 Imaging apparatus 26 Aperture part 28 Compound lens 28A Convex lens part 28B Reflective mirror 28C Objective convex lens part

Claims (5)

A light source for illuminating the inside of the cylinder;
A light guide that guides illumination light from the light source so as to be light in the cylinder and coaxial with the cylinder;
A diaphragm for limiting the opening of the illumination light guided by the light guide;
A convex lens part that is guided by the light guide part and condenses to prevent diffusion of illumination light limited by the diaphragm part;
A convex reflector that reflects the illumination light collected by the convex lens portion over the inner peripheral surface of the cylinder and reflects the reflected light from the inner peripheral surface to an imaging device that images the inside of the cylinder. When,
An objective convex lens portion provided opposite to the inner peripheral surface for irradiating the inner peripheral surface with the illumination light reflected by the reflecting mirror and condensing and receiving the reflected light from the inner peripheral surface When,
Optical system for cylindrical inner surface inspection including   The cylindrical inner peripheral surface inspection optical system according to claim 1, wherein the aperture portion is adjustable in opening size. Further comprising a convex lens portion for illumination for condensing to prevent diffusion of illumination light from the light source,
The inside of the cylinder according to claim 1 or 2, wherein the light guide unit guides the illumination light collected by the illumination convex lens so as to be light in the cylinder and coaxial with the cylinder. Optical system for surface inspection. The light guide part transmits the reflected light from the inner peripheral surface, which is incident through the objective convex lens part, the reflecting mirror, the convex lens part, and the diaphragm part,
The cylindrical inner peripheral surface inspection optical system according to any one of claims 1 to 3, wherein reflected light from the inner peripheral surface that has passed through the light guide portion is incident on the imaging device. An optical system for cylindrical inner surface inspection according to any one of claims 1 to 4,
As an image for inspecting the inner peripheral surface of the cylinder, an imaging device that captures an image representing the inside of the cylinder;
Cylindrical inner surface inspection device.