JP2002022671A - Apparatus and method for inspecting inner wall surface of cylinder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To certainly recognize the flaw of the inner wall surface of a cylinder in spite of the shape thereof. SOLUTION: The conical mirror 13 connected to the front of an image pickup camera 11 is formed in a multistage fashion consisting of a first mirror part 25 equipped with a conical reflecting surface 25a having a vertical angle α, and a second mirror part 27 equipped with a conical reflecting surface 27a having a vertical angle β. The image pickup camera 11 is constituted so that the focal point of a lens is shortened and the field angle thereof is widened and directly picks up the image of the inner wall surface 17 of the cylinder. The camera picks up the image not only in the direction perpendicular to the inner wall surface of the cylinder through the conical reflecting surface 25a, but also from the lower part on the side opposite to the image pickup camera 11 through the conical reflecting surface 27a. The images picked up from three directions are processed by an image processor 21, and the picked-up images from three directions are displayed on a monitor 19 in a concentric circular state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical inner wall surface inspection apparatus and method for inspecting the state of a cylindrical inner wall surface.

[0002]

2. Description of the Related Art An apparatus for inspecting whether or not a defect has occurred on the inner wall surface of a cylinder is disclosed in, for example, Japanese Patent Application Laid-Open No. Hei 6-2417.
No. 60 and JP-A-6-18246. The cylindrical inner wall surface inspection apparatus described in these publications arranges a conical mirror in front of an imaging camera, captures an image of the entire inner peripheral wall of the cylinder obtained by receiving light reflected by the conical mirror, The condition of the inner wall surface of the cylinder is inspected.

[0003]

By the way, in the above-mentioned device, the image captured by the conical mirror is only in one direction perpendicular to the inner wall surface of the cylinder.
Depending on the shape of the defect generated on the inner wall surface of the cylinder, there is a problem that the defect cannot be recognized and the defect inspection cannot be performed reliably.

[0004] For example, as shown in FIG.
In the case where the shape of the defect 3 formed on the cylindrical surface is like a step, when the image is taken in a direction perpendicular to the inner wall surface 1 of the cylinder,
It is difficult to recognize it as a defect because it looks like a line, and the defect is missed, resulting in insufficient inspection accuracy. In FIG. 8, reference numeral 5 denotes an imaging camera, and reference numeral 7 denotes a conical mirror.

Accordingly, an object of the present invention is to make it possible to reliably recognize a defect on the inner wall surface of a cylinder regardless of its shape.

[0006]

According to a first aspect of the present invention, a conical mirror is provided in front of an imaging camera for imaging an inner wall surface of a cylinder such that a vertex is located on the imaging camera side. In the cylindrical inner wall surface inspection device arranged, the conical mirror is configured in multiple stages having a plurality of conical reflection surfaces having different apex angles.

[0007] According to the cylindrical inner wall surface inspection apparatus having such a configuration, an image picked up by the image pickup camera is obtained through a plurality of conical reflecting surfaces having different apex angles, and is provided in a plurality of directions with respect to the cylindrical inner wall surface. From.

According to a second aspect of the present invention, in the configuration of the first aspect, the multi-stage conical mirror is provided with a conical reflecting surface such that the imaging camera can capture an image in a direction perpendicular to the inner wall surface of the cylinder. A first mirror portion, and a conical reflection surface having an apex angle larger than the apex angle of the conical reflection surface of the first mirror portion, wherein the imaging camera can capture an image of the inner wall surface of the cylinder from the side opposite to the imaging camera. And a second mirror portion having a viewing angle such that the imaging camera can directly capture an image on the inner wall surface of the cylinder.

According to the above configuration, the image taken by the image pickup camera is perpendicular to the inner wall surface of the cylinder through the conical reflection surface of the first mirror, and the image taken by the second mirror is There are three directions, one from the side opposite to the imaging camera through the reflecting surface and the one obtained by direct imaging by the imaging camera.

According to a third aspect of the present invention, in the configuration of the second aspect of the present invention, a defect shape judging means for judging the shape of the defect on the inner wall surface of the cylinder is provided based on each image from three directions taken by the imaging camera. There is a configuration.

According to the above arrangement, the defect shape judging means comprises:
The shape of the defect on the inner wall surface of the cylinder is determined based on each image from three directions.

According to a fourth aspect of the present invention, in the configuration of the second or third aspect, a defect position recognizing means for recognizing a position of a defect in each image picked up from three directions by the image pickup camera, and the defect position recognizing means. Among the images in which the defects have been recognized, the defect determining means for determining that the defects in the images in which the circumferential positions of the defects substantially coincide with each other are the same is provided.

According to the above arrangement, the defect position recognizing means comprises:
The position of a defect in each image captured from three directions is recognized, and among the images in which the defect is recognized, the defect in the image in which the circumferential positions of the defects match each other is the same as the defect.
The defect judgment means makes the judgment.

According to a fifth aspect of the present invention, in the configuration of the fourth aspect of the invention, the defect position recognizing means includes a position of the defect in a polar coordinate system represented by a distance from the center of the image and an angle from a specified position in the circumferential direction. , And the defect determining means determines that the defects having substantially the same angle are the same.

According to the above configuration, by recognizing the defect in the polar coordinate system, it can be easily determined whether or not the defect in each image is the same.

According to a sixth aspect of the present invention, in the configuration of the fifth aspect, the imaging camera is constituted by a charge-coupled device having a large number of pixels, and a distance of the defect from the image center is determined by the distance of the charge-coupled device. It is the number of pixels from the center.

According to the above arrangement, the position of the defect in the captured image from the center of the image corresponds to the number of pixels counted from the center of the image.

According to a seventh aspect of the present invention, in the configuration according to any one of the second to sixth aspects, the first image obtained by the first mirror section is displayed in a circle at the center, and the second mirror is displayed. Display in which a second image obtained by the unit is displayed in a ring around the first image, and a third image obtained by directly capturing an image by the imaging camera is displayed around the second image. It is configured to include means.

According to the above configuration, the first image, the second image, and the third image are displayed concentrically adjacent to each other.

[0020] The invention according to claim 8 is that, in front of the imaging camera,
In the cylindrical inner wall surface inspection method for arranging a conical mirror having a vertex positioned on the imaging camera side, inserting the imaging camera and the conical mirror into a cylinder, and inspecting a defect occurrence state of the cylindrical inner wall surface, The shape mirror is configured in multiple stages with a plurality of conical reflecting surfaces having different apex angles, and the imaging camera directly images the image through the plurality of conical reflecting surfaces having the different apex angles and the inner wall surface of the cylinder. With the image,
According to another aspect of the present invention, there is provided a cylindrical inner wall surface inspection method for inspecting a defect of the cylindrical inner wall surface.

According to the above inspection method, the image taken by the imaging camera is taken through a plurality of conical reflecting surfaces having different apex angles, and is taken directly from a plurality of directions with respect to the inner wall surface of the cylinder. It will be.

[0022]

According to the first aspect of the present invention, the conical mirror arranged in front of the imaging camera for imaging the inner wall surface of the cylinder is provided.
Since a plurality of conical reflecting surfaces having different apex angles are provided in multiple stages, a defect on the inner wall surface of the cylinder can be imaged from a plurality of directions, and the defect can be reliably found regardless of the shape of the defect.

According to the second aspect of the present invention, images can be obtained in three directions: one perpendicular to the inner wall surface of the cylinder, one from the side opposite to the imaging camera, and one directly taken by the imaging camera. Therefore, the defect can be found more reliably regardless of the shape of the defect.

According to the third aspect of the present invention, the defect shape judging means for judging the shape of the defect on the inner wall surface of the cylinder is provided based on the images from three directions taken by the imaging camera. The shape of the generated defect can be recognized.

According to the fourth aspect of the present invention, a defect position recognizing means for recognizing the position of a defect in each image picked up from three directions by the image pickup camera, And defect determining means for determining that defects in images whose circumferential positions substantially coincide with each other are the same. Therefore, it is possible to easily specify a defect in each captured image.

According to the fifth aspect of the present invention, the defect position recognizing means recognizes the position of the defect in a polar coordinate system represented by a distance from the center of the image and an angle from a specified position in the circumferential direction,
Since the defect judging means judges the defects having substantially the same angle as the same, it is easy to determine whether or not the defects in each image are the same without performing a complicated calculation process. Can be determined.

According to the sixth aspect of the present invention, the imaging camera comprises:
It is composed of a charge-coupled device having a large number of pixels, and the distance from the image center of the defect is the number of pixels from the center of the charge-coupled device, so the position of the defect in the captured image from the image center can be easily determined. You can ask.

According to the seventh aspect of the present invention, the first image obtained by the first mirror section is displayed in a circular shape at the center, and the second image obtained by the second mirror section is displayed. Since the display device is provided with a display means for displaying a ring around the first image and displaying a third image obtained by directly taking an image by the imaging camera in a ring around the second image, Image of,
The second image and the third image are concentrically adjacent to each other and are easy to see.

According to the eighth aspect of the present invention, the image picked up by the image pick-up camera is picked up through a plurality of conical reflecting surfaces having different apex angles and is also picked up directly to obtain an image. The defect can be imaged from a plurality of directions, and the defect can be reliably found regardless of the shape of the defect.

[0030]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic diagram of a cylindrical inner wall surface inspection apparatus showing an embodiment of the present invention.
The state of the inner wall surface 17 of the cylinder is imaged and inspected by an imaging device 15 having a conical mirror 13 whose apex is located on the imaging camera 11 side. An image processing device 21 having a monitor 19 as a display unit is connected to the imaging device 15. The defect indicated by the symbol N on the inner wall surface 17 of the cylinder is a defect. However, the defect N is extremely small so as to be invisible to the naked eye, and is greatly enlarged for convenience. Further, the shape of the defect N shown in FIG. 1 is not always displayed as it is with respect to the defect image G on the monitor 19, but is actually an image as shown in FIG. .

The conical mirror 13 has a vertex at the top of the imaging camera 1.
The first mirror section 25 is connected to the first mirror section 25 via a connecting rod 23, and the second mirror section 27 is integrated with the first mirror section 25 on the side opposite to the connecting rod 23. The first mirror unit 25 includes a conical reflection surface 25a that allows the imaging camera 11 to capture an image in a direction perpendicular to the cylindrical inner wall surface 17. On the other hand, the second mirror unit 27
The imaging camera 11 has an apex angle β larger than the apex angle α of the conical reflection surface 25 a of the first mirror portion 25, and the imaging camera 11
And a conical reflection surface 27a capable of capturing an image from the side opposite to the imaging camera 11.

As the imaging camera 11, a CCD camera composed of a charge-coupled device having a large number of pixels is used, and an imaging area in the vertical direction by the first mirror unit 25 with respect to the inner wall surface 17 of the cylinder is used. The focal length of the built-in lens is shortened so as to obtain a wide viewing angle that enables direct imaging.

That is, the above-described imaging camera 11 moves the vertical direction indicated by the ray a with respect to the entire circumference of the cylindrical inner wall surface 17,
The image is taken from three directions: a downward direction indicated by a light beam b on the opposite side to the imaging camera 11 in FIG. 1 and an upward direction indicated by a light beam c on the imaging camera 11 side in FIG.

Images taken from the above three directions are displayed on the monitor 1
9, a first image area A obtained by the first mirror unit 25 is displayed in a circle at the center,
The second image area B obtained by the second mirror section 27 is displayed in an annular shape around the first image area A, and the imaging camera 11
The third image area C obtained by directly capturing an image is displayed around the second image area B.

FIG. 2 is a flowchart of an image processing operation by the image processing device 21. First, by capturing images from three directions captured by the imaging camera 11 (step 201), an image as shown in FIG. 3A is obtained. At this point, the contrast between the defect image G and the background has not been clarified.

Next, by extracting edges of a change in high luminance by a vertical and horizontal sobel filter (step 203), as shown in FIG. 3B, the contrast between the defect image G and the background is clearly determined. Become. For this edge extraction, other known methods may be used. Further, in the image shown in FIG. 3B, binarization of light and dark is performed at a predetermined threshold value (step 205), and a dark portion having a luminance equal to or less than a predetermined value is left as a defect image G. Thus, the image shown in FIG. 3C is obtained. The predetermined threshold value may be calculated from the luminance level of the entire image or the like or may be determined in advance, but this is also a known method.

Next, labeling, that is, extraction of a defective portion is performed, and the coordinates of the center of gravity and the area of the defective portion are calculated (step 207). The barycenter coordinates are calculated from the distance from the center of the image and the angle from the specified position in the circumferential direction in the polar coordinate system.
That is, the image processing device 21 includes a defect position recognizing unit that recognizes the position of the defect. In addition, each image A, B,
Since the position from the center of the circular boundary between C is fixed, it can be removed at the time of the labeling. Further, since the coordinates of the center of gravity of the defective portion are obtained in the polar coordinate system, the amount of calculation processing can be reduced.

For example, in the image shown in FIG.
, Three defect images G ₁ , G ₂ , G ₃ displayed in the image area C, the second image area B, and the first image area A, respectively.
Are represented as follows.

G ₁ : Coordinates (200, 10 degrees), Area 18 G ₂ : Coordinates (30, 11 degrees), Area 21 G ₃ : Coordinates (145, 210 degrees), Area 20 The distance from the center of the image representing the coordinates of the center of gravity of the defective portion is the number of pixels counted from the center of the imaging camera 11. The area of the defective portion is represented by the number of pixels corresponding to the defective portion. In other words, Come with the defect image G _1, there is the position of the center of gravity of the defect at the position corresponding to 200 th pixels from the center, the area of the defect will correspond to the pixel 18 min.

Next, it is determined whether or not each of the three image areas A, B, and C has a defect (step 209).
When making this determination, the angle that is the element indicating the coordinate position is
When the image areas A, B, and C are substantially the same, it is determined that the defects are the same. That is, the image processing device 21
Defect determination means is provided for determining defects in images where the positions of the defects in the circumferential direction coincide with each other. For example, in the image of FIG. 3 (c), the angle is 10 degrees defects G ₁ and the defect G _2, since almost the same angle as 11 degrees, the two defects G _1, G ₂ can be judged the same.

Then, in the next step 211, the shape of the defect is determined by estimation. That is, the image processing device 21
Is provided with a defect shape judging means for judging the shape of the defect on the inner wall surface 17 of the cylinder. As shown in the sectional shape of FIG. 4A, five representative shapes [1] to [5] are considered as the defect shape, and FIG. FIG. The image example in FIG. 4B corresponds to the image after the edge extraction in FIG. 3B.

First, the defect shape [1] is set to the cylindrical inner wall surface 17.
Is a hole or a convex portion opened in the vertical direction with respect to the image. Since the hole and the convex portion can be imaged in any of three directions, the defect image G is displayed in all three image areas A, B, and C. You.

The defect shape [2] is a step having a concave portion on the lower side. The step is displayed as a line from the upper direction and the vertical direction, but cannot be clearly imaged as a defect. Only the image can be clearly captured, and is displayed as the defect image G in the second image area B.

The defect shape [3] is a step having a concave upper portion. The step is displayed as a line from the lower and vertical directions, but cannot be clearly imaged as a defect. Only the image can be clearly captured, and is displayed as the defect image G in the third image area C.

In the defect shape [4], a hole is formed in a concave portion on the lower side, and the hole cannot be clearly imaged as a defect because it is displayed as a line from above. The image can be clearly captured only from the vertical direction and the downward direction, and is displayed as the defect image G in the first and second image areas A and B.

In the defect shape [5], a hole is formed in a concave portion on the upper side, and the hole is displayed as a line from below and cannot be clearly imaged as a defect. , Can be clearly imaged only from the vertical and upward directions,
The defect image G is displayed in each of the first and third image areas A and C.

As described above, in step 211, the defect shape is estimated based on which of the three directions the defect can be clearly imaged. That is, as shown in FIG. 4B, the shape of the defect can be estimated based on whether an image is present in any of the upward, downward, and vertical directions (whether the image is clearly displayed or not).

As described above, depending on the shape of the defect, it may not be possible to clearly image (recognize) an image from a certain direction. However, by imaging from three directions as in this embodiment, regardless of the shape of the defect. It is possible to surely recognize the shape without overlooking it and to recognize its shape.

FIG. 5 is an overall configuration diagram showing a state where the inner surface of a valve seat, which is a cylindrical inner wall surface of an automobile engine, is being inspected by the above-described cylindrical inner wall surface inspection apparatus. FIG. 6 is a block diagram thereof. is there. The cylinder head 29 of the four-cylinder engine, which is the object to be inspected, is transported leftward in the figure by the transport device 31, and the inspection control device 33.
Stop at the position corresponding to.

The inspection control device 33 has a total of 1
In order to be able to inspect the inner surfaces of the six valve seats simultaneously,
The measuring head 35 provided with 16 imaging devices 15 shown in FIG. 1 is moved in an appropriate direction, and the conical mirror 13 is advanced to a position corresponding to the valve seat portion. An image processing start signal and defect information are input from the image processing device 21 to the inspection control device 33. The inspection control device 33 outputs an inspection start signal and an inspection result to the line control device 37. Further, although not shown in FIG. 5, the line control device 37 outputs, to the ejection process control device 39, an ejection signal for processing a defective device based on the inspection result. .

FIG. 7 is a flowchart showing the operation of the entire inspection apparatus shown in FIGS. First, an inspection start signal is output from the inspection control device 33 to the line control device 37, and the cylinder head 29 moves to the inspection position corresponding to the inspection control device 33 (step 701), and the cylinder head 29 is positioned at this inspection position. (Step 703).

Next, the measuring head 35 descends, and each imaging device 15 enters the valve seat portion (step 70).
5). In this state, the image processing device 21 outputs an image processing start signal to the inspection control device 33, and each of the imaging devices 15 captures an image of the valve seat portion, obtains an image, detects a defective portion, and executes the image processing. (Step 707).

Then, it is determined whether or not there is a defect (step 709). If there is a defect, the image processing apparatus 21 changes the type, that is, the shape of the defect from [1] to [1] in FIG.
It is determined whether it is one of [5] (Step 71)
1) The defect record is stored in a predetermined memory (step 713). At the same time, the image processing device 21 outputs the defect information to the inspection control device 33, and further outputs the defect information to the inspection control device 3.
3 outputs the inspection result to the line control device 37, and the line control device 37 outputs an ejection signal to the ejection process control device 39 based on the inspection result (step 7).
15), the ejection process control device 39 for ejecting the defective cylinder head 29 in which a defect is found is ejected so as to be taken out of the production line. Finally, the measuring head 35 is raised (step 717) to prepare for the next inspection of the cylinder head.

The data of defect types (shapes) are
It can also be processed statistically and used for analysis of defect generation factors.

The presence or absence of a defect may be determined by visually observing the image obtained as shown in FIG. In addition, the conical mirror 13 not only forms two conical reflection surfaces having different apex angles but also three or four conical reflection surfaces whose apex angle gradually increases from the imaging camera 11 side. It may be formed.

[Brief description of the drawings]

FIG. 1 is a schematic view of a cylindrical inner wall surface inspection apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating an image processing operation performed by the image processing apparatus of FIG. 1;

3A and 3B are images obtained by the image processing apparatus of FIG. 1, wherein FIG. 3A is an image captured by an imaging camera, FIG. 3B is an image obtained by extracting the image of FIG. It is an image obtained by binarizing the image of (b).

4A is a diagram showing a defect shape on an inner wall surface of a cylinder, and FIG. 4B is an image diagram corresponding to each defect shape shown in FIG.

FIG. 5 is an overall configuration diagram showing a state in which the inner surface of the valve seat portion of the automobile engine is inspected by the cylindrical inner wall surface inspection device of FIG. 1;

FIG. 6 is a block diagram of FIG. 5;

FIG. 7 is a flowchart showing an operation of the entire inspection apparatus shown in FIGS. 5 and 6;

FIG. 8 is a schematic view of a cylindrical inner wall surface inspection apparatus showing a conventional example.

[Explanation of symbols]

Reference Signs List 11 imaging camera 13 conical mirror 17 cylindrical inner wall surface 21 image processing device (defect shape determining means, defect position recognizing means, defect determining means) 25 first mirror section 25a, 27a conical reflection surface 27 second mirror section A first 1 image B 2nd image C 3rd image N defect G defect image α, β apex angle

Claims (8)

[Claims] 1. A cylindrical inner wall surface inspection apparatus in which a conical mirror is disposed in front of an imaging camera for imaging an inner wall surface of a cylinder such that a vertex is located on the imaging camera side. A cylindrical inner wall surface inspection apparatus comprising a plurality of stages having a plurality of conical reflecting surfaces. 2. A multi-stage conical mirror, comprising: a first mirror section having a conical reflection surface such that an imaging camera can perform imaging in a direction perpendicular to an inner wall surface of a cylinder; and a cone of the first mirror section. A second mirror portion having a vertex angle larger than the vertex angle of the reflective surface, the image capturing camera having a conical reflective surface capable of capturing an image from the opposite side to the image capturing camera with respect to the inner wall surface of the cylinder, 2. The cylindrical inner wall surface inspection apparatus according to claim 1, wherein the imaging camera has a viewing angle capable of directly imaging the cylindrical inner wall surface. 3. A cylindrical inner wall surface according to claim 2, further comprising a defect shape determining means for determining a shape of a defect on the cylindrical inner wall surface based on images from three directions captured by an imaging camera. Inspection equipment. 4. A defect position recognizing means for recognizing a position of a defect in each image picked up from three directions by an image pickup camera, and a circumferential position of the defect among the images in which the defect is recognized by the defect position recognizing means. 4. A cylindrical inner wall surface inspection apparatus according to claim 2, further comprising a defect judging means for judging the defects in the images substantially identical to each other to be the same. 5. A defect position recognizing means for recognizing a position of a defect in a polar coordinate system displayed by a distance from a center of an image and an angle from a specified position in a circumferential direction, and the defect judging means: The cylindrical inner wall surface inspection apparatus according to claim 4, wherein the determined defects are determined to be the same. 6. An imaging camera comprising a charge-coupled device having a large number of pixels, and a distance from a center of an image of a defect is the number of pixels from a center of the charge-coupled device. 5. The cylindrical inner wall surface inspection apparatus according to 5. 7. A first image obtained by the first mirror unit is displayed in a circular shape at the center, and a second image obtained by the second mirror unit is displayed around the first image. Display in a ring,
The cylindrical inner wall surface according to any one of claims 2 to 6, further comprising display means for displaying a third image obtained by directly taking an image by an imaging camera around the second image. Inspection equipment. 8. A conical mirror whose apex is located on the side of the imaging camera is disposed in front of the imaging camera, and the imaging camera and the conical mirror are inserted into a cylinder. In the cylindrical inner wall surface inspection method to be inspected, the conical mirror is configured in multiple stages with a plurality of conical reflection surfaces having different apex angles, and the imaging camera uses the plurality of conical reflection surfaces having different apex angles. And inspecting the inner wall surface of the cylinder for defects using the image of the inner wall surface and the image directly taken of the inner wall surface of the cylinder.