JPH07190742A - Surface defect detecting method and its device - Google Patents

Abstract

PURPOSE:To detect surface defects in inspection objective areas with high accuracy in a short time. CONSTITUTION:Illuminating optical fibers 2 and light receiving optical fibers 3 are integrally bundled so as to be formed into an inspection end 1, the illuminating optical fibers 2 are connected to an illuminating means 30 so as to allow illuminating light to be fed to each inspection objective area, and concurrently reflecting light from each inspection objective area is led to an optical energy detecting section 10 through the light receiving fibers, reflecting light intensity at each light receiving fiber output end is detected, and based on the aforesaid reflecting light intensity, the presence or absence of surface defects in the inspection objective areas is judged by a defect detecting means 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a defect detecting method and a detecting device for detecting surface defects of a product (work), and more specifically, to accurately detect a defect in a plurality of inspection target portions scattered over a wide range in a short time. The present invention relates to a defect detection method and a defect detection apparatus using the method.

[0002]

2. Description of the Related Art Conventionally, it is general to visually inspect for the presence or absence of surface defects after machining a workpiece. However, the visual inspection is inefficient in working efficiency, and there is a problem that the inspection takes time if there are many inspection target parts.
Further, when the size of the portion to be inspected is small or there are many fine defects, there is a problem that defects are overlooked.

In order to solve the above-mentioned problems, the applicant of the present invention image-processes an image of a portion to be inspected taken by using an industrial TV camera (ITV camera), whereby surface defects and processing roughness of the work are processed. , Japanese Patent Application No. 4-152048 has already proposed a work surface characteristic amount detecting device capable of detecting a work surface characteristic amount such as a processing dimension.

In the apparatus proposed in the above-mentioned Japanese Patent Application No. 4-152048, the contour of a digital image obtained by digitally converting the image signal of the region to be inspected photographed by using the ITV camera and the processing standard dimension are used. A mask image is generated using the mask image, and the digital image is masked using this mask image to extract the image signal of only the inspection target portion, and the surface defect or the like is detected from the brightness of each portion of the inspection target portion. It is a thing.

In the above apparatus, since the mask image is generated based on the image of the inspection target portion actually photographed by the ITV camera, the positioning accuracy between the work and the detection end and the work processing accuracy are affected. Since an appropriate mask image can be obtained without any human intervention, it is possible to perform 100% product inspection at high speed without human intervention.

[0006]

However, the above-mentioned Japanese Patent Application No. 4
A method of detecting a surface defect or the like of an inspection target portion by directly capturing an image of the inspection target portion using an ITV camera and processing the obtained image signal as in the device proposed in -152048. While extremely accurate inspection is possible, multiple inspection targets with a small area (valve seat If the surfaces are scattered, it is not possible to inspect all of the inspection target parts at the same time, and there is a problem that it takes time to inspect all of the plurality of inspection target parts.

That is, in order to simultaneously inspect all the parts to be inspected, it is necessary to photograph all the objects to be inspected at one time by the ITV camera and perform image processing once. However, as described above, when a plurality of inspection objects having a small area are scattered in a relatively large area, if the images of all the inspection objects are to be captured at once, the inspection objects are scattered over a wide area. The range (for example, the entire top surface of the cylinder head) must be photographed at one time, and the ratio of the area occupied by each inspection target region to the entire image becomes extremely small. Therefore, there is a problem in that it is not possible to detect a minute surface defect due to the limitation of the resolution of the ITV camera, and the defect detection accuracy is significantly reduced. Further, since the shape of the valve seats and the like restricts the optimum illumination and shooting directions for defect detection, if all the valve seats were shot by one ITV camera at the same time, However, there is a problem in that it is not possible to obtain optimum illumination and shooting directions at the same time, and it is difficult to detect defects.

Therefore, when an apparatus such as Japanese Patent Application No. 4-152048 is used to inspect the valve seat surface of a multi-cylinder engine cylinder head, in order to improve the defect detection accuracy, the images are taken at once. The range in which the image processing is performed needs to be limited to only a part of one inspection target site (valve seat). For this reason, in the above method, the operation of performing photographing and image processing several times for each valve seat is repeated to inspect all the valve seats. However, taking an example of a valve seat of an engine, each cylinder has two intake and exhaust valves.
In the case of a valve-type engine, even in the case of a standard 4-cylinder engine, there are 16 valve seats (inspection target parts) per cylinder head, and therefore, as described above, several shots and image processing are performed for each valve seat. If repeated, the time required for the inspection becomes extremely long, which may cause a problem in the process.

Even with the above method, it is possible to shorten the inspection time to some extent by inspecting several valve seats at the same time by using a plurality of inspection devices. However, providing a plurality of inspection devices is an equipment. This is not preferable because it causes an increase in cost and an increase in the number of equipment operators. SUMMARY OF THE INVENTION It is an object of the present invention to solve the above problems and provide a surface defect detecting method capable of accurately detecting a surface defect of an inspection target portion in a short time, and a surface defect detecting apparatus using the method.

[0010]

According to the present invention as set forth in claim 1, one end of each of a plurality of optical fibers for illumination and one optical fiber for receiving light is integrally bundled to form a detection end, and the detection end is formed. In close proximity to the inspection target portion, and the other end of each of the illumination optical fibers is connected to a light source, and the illumination light is supplied to the inspection target portion from the detection end via each of the illumination optical fibers. The reflected light at the inspection target portion is received by the end faces of the receiving optical fibers facing each other, and the other end of each receiving optical fiber is guided to the light amount detecting means, and each receiving optical fiber receives the light. There is provided a surface defect detection method for determining the presence or absence of a defect on the surface of the inspection target portion where the detection end side end surface of each light receiving optical fiber faces by determining the intensity of the reflected light.

According to the present invention as defined in claim 2,
Further, the inspection target portion is divided into a plurality of regions, and illumination light having a different frequency is supplied to each region via the illumination optical fiber facing each region, and the light amount detection means is provided for each of the light receiving lights. There is provided a surface defect detecting method for determining the intensity of the reflected light of the frequency of the illumination light supplied to the region where the respective light receiving optical fibers face each other, of the reflected light received by the fiber.

Further, according to the invention of claim 3,
The surface defect detection method according to claim 1,
The detection end is formed in the same number as the number of a plurality of inspection target parts, and each detection end is arranged in close proximity to the corresponding inspection target part at the same time to face each other, and the light receiving optical fiber from each of the detection ends has one light amount. There is provided a surface defect detecting method which guides the light to the detecting means and simultaneously judges the intensity of the reflected light received by each of the light receiving optical fibers, thereby simultaneously judging the presence or absence of the surface defect in the plurality of inspection target portions.

According to the present invention of claim 4,
In order to carry out the surface defect detection method according to claim 1,
Each of a plurality of illumination optical fibers and one end of a light receiving optical fiber are formed by bundling together one end, and a detection end that is arranged in opposition in close proximity to the site to be inspected, and the detection end of each of the illumination optical fibers. One end on the opposite side is connected, and a light source that supplies illumination light from each of the detection ends to the inspection target site via the illumination optical fiber, and one end on the opposite side of the detection end of each of the light receiving optical fibers Based on the light intensity detection means that is connected and detects the intensity of the reflected light received by the respective detection ends of the light receiving optical fiber, and the light intensity detected by the light amount detection means, the detection ends of the respective light receiving optical fibers There is provided a surface defect detection device including defect detection means for determining the presence / absence of a defect on the surface of the inspection target portion facing each other.

Further, in the present invention according to claim 5, in the surface defect detecting device according to claim 4, the inspection target portion is divided into a plurality of regions, and the light source is for illumination facing each of the regions. The light amount detecting means includes means for supplying illumination light having different frequencies to the respective areas via the optical fibers, and the light amount detecting means has respective light receiving optical fibers facing each other among the reflected light received by the light receiving optical fibers. There is provided a surface defect detection device adapted to detect the intensity of reflected light having the frequency of the illumination light supplied to the area.

According to the present invention of claim 6,
The surface defect detection device according to claim 4 or 5, wherein a plurality of the detection ends, the number of which is the same as the number of inspection target parts, and the single light amount detection to which the light receiving optical fibers from the respective detection ends are connected. Means for detecting the intensity of the reflected light received by the light-receiving optical fibers of all the detection ends at the same time. Then, the defect detection unit is configured to simultaneously determine the presence or absence of a defect on the surface facing the detection end of each light receiving optical fiber of each inspection target site based on the light intensity detected by the light amount detection unit.

[0016]

According to the present invention as set forth in each claim, the detecting end is formed by integrally bundling one ends of the illumination optical fiber and the light receiving optical fiber. At the time of inspection, these detection ends are arranged at facing positions close to the inspection target site, the other end of each illumination optical fiber is connected to the light source, and each inspection site from the detection end side of the illumination optical fiber. Illumination light is supplied to.

Further, the ends (output ends) of the respective receiving optical fibers opposite to the detecting ends are connected to the light amount detecting means, and are incident on the detecting end side of the receiving optical fibers from the respective inspection target portions. The reflected light at the inspection target portion is guided to the light amount detecting means. When there is a surface defect at the inspection target portion where each of the light receiving optical fibers faces each other, the reflected light is scattered at the defect portion, so that the intensity of the reflected light incident on the detection end side of the light receiving optical fiber decreases. Therefore, the intensity of the light emitted from the output end of the optical fiber facing the surface defect of the portion to be inspected to the light amount detecting means is lower than that of other optical fibers. Therefore, by determining the light intensity at the output end of each light receiving optical fiber, it is possible to accurately determine the presence or absence of a surface defect in the inspection target portion in a short time.

At each detection end, since the illumination optical fiber and the light receiving optical fiber are bundled together, their positional relationship is fixed, and at the time of detection, the incident angle of the illumination light and the light receiving angle of the reflected light are Is always maintained in a preset angular relationship that is optimal for defect detection. Further, since the flexible optical fiber is used, each detection end can be easily attached in a short time at an accurate position even on an inspection target portion having a complicated arrangement.

On the other hand, when the inspection target portion is composed of a plurality of surface regions having an angle with each other, the reflected light in the adjacent region is incident on the light receiving optical fiber for receiving the reflected light in a certain inspection region. In some cases, the accuracy of defect detection is reduced. In the present invention described in claim 2 and claim 4, the frequency of the illumination light is changed for each region, and the reflected light of the frequency corresponding to each region among the reflected light that enters the light receiving optical fiber in each region. By determining the light intensity of the light, it is possible to eliminate the influence of the reflected light in other inspection areas and accurately detect the surface defects in the respective areas.

Further, according to the present invention as set forth in claims 3 and 6, a plurality of detection ends are provided, and the detection ends are simultaneously arranged at a plurality of inspection target parts, and the optical fibers for receiving light from the respective detection ends are provided. By connecting the output end of the to a single light amount detection means and determining the intensity of the reflected light incident on each light receiving optical fiber at the same time, it is possible to simultaneously inspect a plurality of inspection target parts. , The inspection time is further shortened.

[0021]

Embodiments of the present invention will be described below with reference to the accompanying drawings. In the drawings of each embodiment, the same elements will be described with the same reference numerals. FIG. 1 is a schematic diagram showing an example of the overall configuration when inspecting a valve seat portion of a multi-cylinder engine cylinder head using an inspection apparatus that uses the defect detection method according to the present invention.

In FIG. 1, 50 is a cylinder head (workpiece) of the engine, and 51 and 52 are valve seats for the intake valve and the exhaust valve, which are machined on the cylinder head. Further, in FIG. 1, the whole is shown by 1, a detection end for detecting a defect of each valve seat portion, 2 an illumination optical fiber for supplying illumination light to an inspection target portion, and 3 a light receiving optical fiber. . Optical fiber 2 for illumination and optical fiber 3 for receiving light
In the portion of the detection end 1, they are bundled together as described later, but in the portion apart from the detection end 1, they are branched and independent from each other, and the illumination optical fiber 2 is an illumination device 30 described later. In addition, the light receiving optical fiber 3 is connected to a light amount detecting device 10 described later. The output of the light amount detection device 10 is supplied to the defect detection device 20 described later.

Further, reference numeral 5 in FIG. 1 denotes a rotary shaft to which the detection end 1 is fixed. The rotating shaft 5 is rotatably held at the center of the valve seat by a supporting device (not shown), and the rotating shaft 5 is rotated by a rotary drive source 6 such as a motor, so that the detection end 1 surrounds the inspection target portion of the valve seat all around. It is designed to scan over. Since the workpiece 50 to be inspected in this embodiment is a cylinder head of a 4-cylinder engine having two intake valves and two exhaust valves per cylinder, the number of valve seats to be inspected is 16 per cylinder head. become. Further, each of the valve seat portions 51 and 52 is relatively small, having a diameter of about 30 millimeters, and is arranged on the upper surface of the work (engine cylinder head) 50 as shown in FIG. Therefore, if all the valve seats are photographed at once using an ITV camera and an attempt is made to extract defects by image processing, the ratio of the area of the inspection target portion (valve seat) to the area of the entire image (entire upper surface of the cylinder head). Is extremely small, the size of the defect that can be detected by the resolution of the ITV camera is limited as described above, and there is a problem that the defect detection accuracy is reduced.

FIG. 2 shows a cross section of the valve seat portions 51, 52 of the cylinder head 50 taken along the valve axis. As can be seen from FIG. 2, the inspection target portion 54 of the valve seat portions 51, 52 has a conical surface shape. Therefore, if the illumination and the photographing are performed from one direction, the shadow is always generated, and it is impossible to obtain the optimum illumination and the photographing angle for all the valve seats.

Therefore, the above-mentioned Japanese Patent Application No. 4-152048.
In the No. issue, the region to be imaged at one time is narrowed down to a part of the inspection target portion 54, and image pickup, image processing,
The defect inspection is performed by repeating the determination operation several times. Therefore, in order to complete the inspection of the cylinder head having 16 valve seats as in the present embodiment, the number of operations of the image pickup, the image processing, and the determination is extremely large, and the time required for the inspection is large. The problem of lengthening occurs.
In the present embodiment, by using the detection end 1 as shown in FIG. 3, the inspection target portion of the valve seat is scanned, and the entire inspection of one valve seat is performed by one operation, thereby shortening the inspection time. ing.

FIG. 3 is a diagram showing details of the detection end 1 of this embodiment. In FIG. 3, reference numeral 4 denotes a holder for bundling the illumination optical fiber 2 and the light receiving optical fiber 3 and holding them in place. As shown in FIG. 3, the holder 4 has an end surface 7 that is close to and in opposition to the inspection target portion 54 of the valve seat.
On the end face 7, the end portion of the light receiving optical fiber 3 and the end portion of the illuminating optical fiber 2 are arranged in a row at a predetermined interval in the width direction of the inspection target portion 54.

At the time of detecting a defect, the holder 4 is held by the rotating shaft 5 so that the end surface 7 faces the inspection object portion 54 at a predetermined interval. In this state, the illumination device 30 irradiates the inspection target portion 54 with the illumination light through the respective illumination optical fibers 2, so that the end portions of the respective light receiving optical fibers 3 are exposed on the surface of the opposing inspection target portion 54. The reflected illumination light enters. Further, when the inspection target portion 54 has a surface defect, the illumination light is scattered at the defect portion, so that the intensity of the reflected light incident on the end portion of the light receiving optical fiber 3 facing the defect portion is reduced. Therefore, as will be described later, by rotating the rotary shaft 5 and scanning the inspection target portion 54 with the detection end 1 over the entire circumference of the valve seat, the inspection target portion 54 is scanned.
The presence or absence of the above surface defects can be detected.

The illuminating optical fiber 2 is oriented so that the illuminating light is uniformly supplied to the surface 54 to be inspected at a predetermined angle from an oblique direction so that the surface defects appear clearly as shadows. . Further, as shown in FIG. 1, the illuminating optical fiber 2 and the light receiving optical fiber 3 are branched at a portion separated from the holder 4 by a predetermined distance to form independent optical fiber bundles to form an illuminating device described later. 30 and light amount detection device 10
Connected to and respectively.

FIG. 4 shows the structure of the illuminating device 30 to which the illuminating optical fiber 2 from each detecting end 1 is connected.
The illuminating device 30 includes the illuminating optical fibers 2 from the detecting end 1.
And an optical fiber holder 31 for fixing the end face thereof in a fixed direction, and a light source 32 such as a high-intensity lamp arranged so that the illuminating light enters perpendicularly to the end face of each optical fiber 2 for illumination. The illumination light from the light source 32 is evenly distributed from the detection end 1 to the inspection target portion 54 of the valve seat through each illumination optical fiber.

FIG. 5 is a diagram showing the structure of the light quantity detecting device 10 to which the light receiving optical fiber 3 from each detecting end 1 is connected. In this embodiment, the light amount detection device 10 has a light-receiving optical fiber holder 12 for holding the end portions (output ends) of the respective light-receiving optical fibers 3 in a predetermined direction in a line as shown in FIG. The CCD line sensor 11 and an image forming lens 17 for forming an image of each output end of the light receiving optical fiber 3 on the CCD line sensor 11 are provided.

The CCD line sensor 11 is a charge-coupled device (char) that generates a voltage signal according to the intensity of incident light.
The image of the output end of each light receiving optical fiber 3 is formed on the corresponding element of the line sensor 11 by the imaging lens 17. Output signals from the respective elements of the line sensor 11 are sent to the defect detection device 20 via the cable 15,
It is compared with a preset threshold value by a comparison circuit in the device.

As described above, since the intensity of the reflected light incident on the end portion on the detection end side of the light receiving optical fiber 3 decreases when the end portion of the light receiving optical fiber faces the surface defect portion, it faces the surface defect portion. The output voltage of the line sensor 11 element receiving the light from the output end of the light receiving optical fiber decreases. For this reason,
The presence or absence of surface defects can be detected by appropriately setting the threshold value. That is, when the detection end 1 is moved along the inner peripheral surface of the inspection target portion 54 by the rotating shaft 5, the output voltage of the element of the line sensor 11 is stable at a high level and does not change when there is no surface defect. . However, if a surface defect exists in the inspection target portion, the output voltage of the element that receives the light of the light receiving optical fiber facing the defective portion when the detection end 1 passes through the surface defective portion becomes lower than the threshold value.

Therefore, the presence or absence of the surface defect of the inspection target portion 54 is checked by monitoring the change in the output voltage of each element of the line sensor 11 while the inner peripheral surface of the inspection target portion 54 is being scanned by the detection end 1. Can be accurately detected. Then, the work in which the surface defect is detected is taken out from the inspection step and regenerated as a raw material. Further, the work whose surface defect is not detected is supplied to the next process.

In the present embodiment, the defect detecting device 20 notifies the operator by turning on a warning light or the like when the output voltage of any of the elements of the line sensor 11 falls below a threshold value during scanning. . According to the present embodiment, the inspection of one valve seat is completed by setting the rotary shaft 5 at a predetermined position of the valve seat and scanning the inner peripheral surface of the valve seat with the detection end 1. Since the inspection can be completed in one step, the inspection time is greatly reduced compared to the case where the inspection surface of the valve seat is divided into multiple areas and the operations such as imaging, image processing and judgment are performed for each area. It becomes possible to do.

In the above embodiment, the inner peripheral surface of the valve seat is scanned by the detecting end 1 in which the light receiving optical fiber 3 and the illuminating optical fiber 2 are arranged at right angles to the scanning direction, so that a defect is generated without performing image processing. Although detection is performed, instead of scanning the inner peripheral surface, the entire circumference of the inner peripheral surface of the valve seat is simultaneously imaged by using a detection end as shown in FIGS. 13 and 14 described later to perform image processing. Therefore, even if the inspection of one valve seat is completed in one step, the inspection time can be similarly shortened.

Next, a second embodiment of the present invention will be described.
In the above-described embodiment, the inspection target portion of the valve seat is a single conical inclined surface. On the other hand, in the present embodiment, as shown in FIG.
4 shows a surface defect detecting method and apparatus particularly effective for inspection of a valve seat having 4, 55, 56.

Also in this embodiment, the entire structure of the apparatus is the same as that shown in FIG.
Is moved to scan the inner peripheral surface of the valve seat, and the surface defect of the inspection target portion is detected. FIG. 7 is a diagram showing details of the detection end 1 used in this embodiment. In FIG. 7, the end surface 7 of the detection end 1 is the inspection target surfaces 54, 55, 56, respectively.
Faces 7a, 7b, 7 which are angled to face each other.
The optical fiber 2 for illumination and the optical fiber 3 for receiving light are arranged on the respective surfaces 7a to 7c.

Also in this embodiment, similarly to the above-described embodiments, the illumination light is supplied from the illuminating device 30 to each inspection target surface through the light receiving optical fiber 2, and the reflected light from each inspection target surface is received. The presence or absence of a surface defect is detected by receiving light with the optical fiber 3. However, when a plurality of surfaces to be inspected that form an angle with each other as in this embodiment are used for inspection by this method,
The reflected light on the other surface to be inspected will be incident on the light receiving optical fiber facing the adjacent surface to be inspected,
The detection accuracy of surface defects may decrease.

That is, since the respective surfaces to be inspected have different inclinations, the illumination light supplied from the corresponding optical fiber 3 for illumination to the respective surfaces to be inspected is directed in the direction corresponding to the inclination of the respective surfaces to be inspected. Will be reflected.
For this reason, for example, in FIG. 7, the irradiation is performed from the illumination optical fiber 2b on the surface 7b of the detection end 1 and the inspection target surface 55
A part of the light reflected by will also enter the light-receiving optical fiber 3c of the adjacent surface 7c of the detection end 1. For this reason,
Even if the light receiving optical fiber 3c on the surface 7c passes through the surface defect portion, the decrease in the intensity of the received light is reduced, and the defect detection accuracy in the light receiving optical fiber 3c is reduced.

In the present embodiment, as will be described later, while supplying light of different frequencies from the respective illumination optical fibers to the inspection target surface, of the reflected light incident on the respective light receiving optical fibers, the opposite inspection target surface is provided. The above problem is solved by detecting the intensity of light having a frequency equal to the frequency of the illumination light with which the light is irradiated to determine whether there is a defect. This allows
Since the illumination optical fibers of different frequencies are supplied from the respective illumination optical fibers to the regions of the inspection target surface, the influence of the reflected light from the other inspection target surfaces is eliminated, and the defect detection accuracy can be improved.

FIG. 8 shows the details of the illumination device 30 used in this embodiment. In FIG. 8, reference numeral 31 denotes an illuminating optical fiber holder for fixing and holding each illuminating optical fiber 2 from the detection end 1 in a line with its end face directed in a fixed direction, and 32 denotes a light source such as a high-intensity lamp. Further, 33 is a filter array for supplying transmitted light of different frequencies to the respective illumination optical fibers, and 34 and 35 are condenser lenses for converging the illumination light from the light source 32 on the end faces of the respective illumination optical fibers. Is.

FIG. 9 shows the filter array 33 of FIG.
The filter array 33 includes optical filters 33a, 33b, ... Having different transmission frequencies at positions corresponding to the end faces of the respective optical fibers for illumination. Therefore, the illumination light supplied from the condenser lenses 34, 35 passes through the respective optical filters 33a, 33b, ... And enters only the light of different frequencies into the end portions of the respective illumination optical fibers. It is like this. As a result, each inspection target surface is irradiated with illumination light of a different frequency for each illumination optical fiber.

Next, FIG. 10 shows the details of the light amount detecting device 10 used in this embodiment. Light amount detection device 10 of the present embodiment
The light receiving optical fiber holder 12 for holding the output ends of the respective light receiving optical fibers in a predetermined position in a row, and the CCD line sensor 1 as in the light amount detecting device (FIG. 5) of the above-described embodiment.
1 and the imaging lens 17. In addition, between the output end of each light receiving optical fiber and the imaging lens 17, as shown in FIG.
A filter array 14 having the same configuration as that of is provided.
The filter array 14 transmits only light having a frequency equal to the frequency of the illumination light with which the light receiving optical fiber detection end faces the inspection target surface area facing the light receiving optical fiber output end. It has an optical filter. Therefore, only the reflected light of the illumination light emitted to the respective light receiving optical fiber detecting ends enters the CCD line sensor 11 from the respective light receiving optical fiber detecting ends.

Also in this embodiment, the output of the CCD line sensor 11 is guided to the defect detecting device 20 similar to that shown in FIG. 5, and the defect is detected by the same method as in the above-mentioned embodiments.
Then, the work in which the surface defect is detected is taken out from the inspection step and regenerated as a raw material. Further, the work whose surface defect is not detected is supplied to the next process. According to this embodiment, each of the light receiving optical fibers faces the inspection target surface with illumination light having a different frequency for each illumination optical fiber, and among the reflected light input to each light receiving optical fiber detection end, the light receiving optical fibers face each other. By detecting only the intensity of light with a frequency equal to the frequency of the illumination light that illuminates the area to be inspected, the influence of reflected light from other parts of the inspection surface is eliminated and surface defect detection accuracy is improved. It becomes possible.

In this embodiment, as shown in FIGS. 8 and 10, a filter array is incorporated in the illuminating device 30 and the light amount detecting device 10. However, as shown in FIG. The corresponding ends of the optical fiber for illumination and the optical fiber for receiving light are set as one set, and the optical filters 33a, 33b, ... Having different transmission frequencies for each set are mounted on the surface 7 of the detection end 1. Good. In this case, the illuminating device 30 and the light amount detecting device 10 are not shown in FIG.
It is not necessary to provide the filter arrays 33 and 14 of 0, and it is possible to have the same configuration as that in FIGS. 4 and 5, and there is an advantage that the device is simplified.

Further, in the present embodiment, the frequencies of the illumination light and the reflected light to be detected are changed for each of the illumination optical fiber and the light receiving optical fiber. However, for example, an optical fiber having a small diameter is used for the illumination light. When the fibers and the light receiving optical fibers are densely arranged, the plurality of illumination optical fibers and the light receiving optical fibers may be set as one group and the frequency may be changed for each optical fiber group.

Further, in the present embodiment, when the inspection target portion is composed of a plurality of surfaces having different inclinations, the problem that the surface defect detection accuracy is lowered by the reflected light from the adjacent surfaces has been described. Similar problems may occur even when the inspection target portion is composed of a single plane. That is, when a large number of illumination optical fibers are arranged at the detection end 1 as shown in FIG. 3, there is a possibility that reflected light from a region other than the opposing inspection target region may be incident on the light receiving optical fibers and the defect detection accuracy may be reduced. There is. Therefore, also in the embodiments of FIGS. 2 and 3, if the frequency of the illumination light is changed for each illumination optical fiber and only the reflected light intensity of the corresponding frequency is detected as in this embodiment, the surface is further increased. The defect detection accuracy can be improved.

Next, a third embodiment of the present invention will be described. In each of the above-described embodiments, one inspection target portion (valve seat) is inspected at a time, and the same inspection is repeated for all inspection target portions, so that the number of inspection target portions of one product is increased. Is increased, there is a problem that the time required for inspection is increased accordingly. In the embodiment described below, the time required for the inspection is shortened by simultaneously inspecting a plurality of inspection target parts at one time, and this problem is solved.

FIG. 12 is a diagram showing the entire inspection apparatus of this embodiment. In FIG. 12, 50 is an engine cylinder head (workpiece) similar to that shown in FIG. 1, and 51 and 52 are valve seats for the intake valve and the exhaust valve, which are processed on the cylinder head, respectively. In FIG. 12, the whole is shown by 1 as a detection end for detecting a defect in each valve seat portion, and 2
Is an optical fiber for illumination that supplies illumination light to the site to be inspected,
Reference numeral 3 denotes a light receiving optical fiber. The illuminating optical fiber 2 and the receiving optical fiber 3 are bundled together at the detecting end 1 portion as described later, but are branched and independent from each other at the distant portion from the detecting end 1. The illumination optical fiber 2 connected to each detection end is connected to the illumination device 30, and the light reception optical fiber 3 connected to each detection end is entirely connected to the light amount detection device 10 described later. Light intensity detector 1
The output of 0 is supplied to the defect detection device 20. Also, 25
Is a monitor connected to the defect detection apparatus 20. FIG.
Shows the appearance of the detection end 1, and FIG. 14 shows a cross section along the axis of the detection end 1. In this embodiment, for each valve seat,
In order to inspect the inspection target portion 54 shown in FIG.
3. Using the detection end 1 having the shape shown in FIG. 14, 16 valve seats are divided into an intake valve valve seat 51 and an exhaust valve valve seat 52, and 8 seats are provided for each of 8 seats.
The inspection is performed once, and a total of eight detection ends are used.

In FIGS. 13 and 14, 4 is a holder for bundling the illumination optical fiber 2 and the receiving optical fiber 3 and holding them in place, and 41 is a guide extending from the holder 4 in the axial direction. Indicates. FIG. 15 shows V- of FIG.
5 shows a cross section of an optical fiber bundle along the V line. As shown in FIG. 15, the illumination optical fiber 2 includes the light receiving optical fiber bundle 3
Are bundled by the holder 4 so as to surround the circumference of. Further, in the holder 4, the illumination optical fiber bundle 2 and the light receiving optical fiber bundle 3 are each expanded in a conical shape, and at the end face facing the inspection target portion, the end portion of the light receiving optical fiber 3 and the illumination optical fiber bundle 3 are illuminated. The ends of the optical fibers 2 are fixed to the holder 4 so as to be oriented in a predetermined direction and exposed in an annular shape.

When a defect is detected, the holder 4 inserts the guide 41 into the valve stem guide 58 of the intake valve or the exhaust valve as shown in FIG. 14 so that the end surface of the holder 4 is in contact with the upper surface of the cylinder head 50. It is attached to the valve seat part 51 or 52 so that it becomes. As a result, the holder 4 is positioned by the valve stem guide 58 and the upper surface of the cylinder head 50, so that the end surface of the illumination optical fiber 2 and the end surface of the light receiving optical fiber 3 are in a fixed relative positional relationship with the inspection target portion 54 of the valve seat. It becomes easy to attach the holder 4 to the valve seat portion so as to maintain the above condition.
The light-receiving optical fiber 3 is oriented so that the end surface of the light-receiving optical fiber 3 faces the entire area of the inspection target surface 54 with a predetermined gap when the holder 4 is positioned in the valve seat portion as described above. ing. Also, the optical fiber 2 for illumination
Are oriented so that the illumination light is uniformly supplied from the oblique direction to the inspection target surface 54 at a predetermined angle so that the surface defect portion clearly appears as a shadow.

Further, as shown in FIG. 14, the illumination optical fiber 2 and the light receiving optical fiber 3 are branched at a portion distant from the holder 4 by a predetermined distance to form independent optical fiber bundles for illumination. They are connected to the device 30 and the light amount detection device 10, respectively. FIG. 16 shows a configuration of the illumination device 30 to which the illumination optical fiber 2 from each detection end 1 is connected. The illuminating device 30 illuminates the illuminating optical fiber 2 from each detecting end 1 perpendicularly to the illuminating optical fiber holder 31 that holds the illuminating optical fiber 2 in a fixed direction with its end face fixed. A light source 32 such as a high-intensity lamp arranged so that light is incident is provided, and the illumination light from the light source 32 is evenly distributed to the inspection target portion 54 of the valve seat via each illumination optical fiber.

FIG. 17 is a diagram showing the structure of the light amount detecting device 10 to which the light receiving optical fiber 3 from each detecting end 1 is connected. In the present embodiment, the light amount detection device 10 includes each detection end 1
A light-receiving optical fiber holder 12 for fixing and holding the end portion of the light-receiving optical fiber 3 from a fixed direction in a predetermined direction.
An ITV camera 13 for photographing the entire end of each light-receiving optical fiber 3 held by the holder 12 is provided.

In order to improve the surface defect detection accuracy of each inspection target portion, the ends of the light receiving optical fibers 3 from the respective detection ends are arranged on the holder 12 as close as possible to each other.
The photographing magnification of the ITV camera 13 is set to the maximum within a range in which the entire end portions of these light receiving optical fibers can be photographed at one time. FIG. 18 shows the ITV camera 1 of the light amount detection device 10.
3 shows the arrangement of the ends of the optical fibers 3 at the respective detection ends on the image photographed in 3. In this embodiment, since the end portions of the light-receiving optical fiber 3 from the eight detection ends need to be simultaneously photographed at the highest magnification, the end portions of the light-receiving optical fiber 3 from the respective detection ends on the holder 12 are shown in FIG. In order to effectively use the field of view of the ITV camera 13 as shown in FIG.

As shown in FIG. 17, the light amount detecting device 10 is connected to the defect detecting device 20 via the cable 15, and the image signal photographed by the ITV camera 13 is image-processed in the defect detecting device 20. It That is, the image signal is divided into a plurality of pixels in the defect detection device 20, and the analog signal indicating the brightness of each pixel is converted into a digital image signal of multiple gradation levels (for example, 256 gradations) by the AD converter. . The digital image signal for each pixel is further binarized using an appropriate threshold value, and the obtained binarized image is stored in the frame memory in the defect detection device 20.

The defect detecting device 20 is connected to the monitor 25 via the cable 15, and the binarized image stored in the frame memory of the defect detecting device 20 can be displayed on the monitor 25 as needed. it can. As described above, when uniform illumination light is supplied from the illumination optical fiber 2 to the inspection target surface 54 of the valve seat in an oblique direction in FIG. 14, the reflected light is scattered at the surface defect portion on the inspection target surface. Therefore, the intensity of the reflected light that is incident on the optical fiber 3 facing the surface defect portion is reduced. Therefore, the light amount detection device 1
Optical fiber 3 for receiving light on the side fixed on the holder 12
At the end, only the end of the optical fiber facing the surface defect portion has a lower brightness than the other end of the optical fiber.
FIG. 19 shows the state of the end portion of the light receiving optical fiber 3 on the light amount detection device 10 side at this time. Shown by A to C in FIG. 19 are the end portions of the optical fiber directly facing the surface defect portion, which are darker than the other end portions of the optical fiber.
Therefore, by setting the threshold value at the time of the above-described binarization processing in the defect detecting device 20 to an appropriate value, the optical fiber with low lightness is displayed in the image of the end of the light receiving optical fiber 3 from each detection end. Since it is possible to easily determine whether or not the edge exists, it is possible to simultaneously determine the presence or absence of the surface defect in each inspection target portion. Then, the work in which the surface defect is detected is taken out from the inspection step and regenerated as a raw material. Further, the work whose surface defect is not detected is supplied to the next process.

In the cylinder head of this embodiment, the diameter of each valve seat is about 30 millimeters, and the area of the annular inspection target portion 54 of the valve seat is about 220.
It will be a square millimeter. Further, in the present embodiment, since one optical fiber having a diameter of 0.3 mm is used as the light receiving optical fiber, approximately 3000 optical fibers are used to inspect the entire area of one inspection target portion 54 without omission. An optical fiber bundle composed of optical fibers is used as the light receiving optical fiber 3.

Further, the defect detecting device 2 used in this embodiment
0 uses a frame memory of 512 × 512 pixels. Therefore, as shown in FIG. 18, 8 rows are arranged in 3 rows × 3 rows.
When the light-receiving optical fiber ends from one detection end are arranged on the image, the total amount of the light-receiving optical fiber ends (composed of about 3000 optical fibers) from one detection end is about 1 A number of pixels of / 9 (about 29000 pixels) is used.
Therefore, one end of the optical fiber (diameter 0.3 mm) is displayed on the image with about 9 pixels (29000/3000), and the range of the inspection target portion displayed by one pixel (that is, defect detection accuracy) is , Approximately 0.1 mm × 0.1 mm.
Generally, surface defects such as blowholes that are likely to occur in the valve seat portion have a diameter of about 0.3 mm to 1 mm. Therefore, according to the detection apparatus of the present embodiment, surface defects can be detected with high accuracy. Will be possible.

Further, according to this embodiment, since the detecting end and the light quantity detecting device and the illuminating device are connected by using the flexible optical fiber for illumination and the optical fiber for receiving light, it is possible to The detection end can be easily set on the inspection target portion regardless of the shape or the position of the inspection target portion. Also,
Since the optical fiber for illumination and the optical fiber for receiving light are bundled together and fixed at the detection end, it is necessary to set the optimal illumination and light receiving angles in the holder 4 in advance in accordance with the shape of the inspection target portion. The optimum illumination and light receiving angles can always be obtained simply by setting the detection end on the inspection target site. Therefore, the time required for the adjustment for the inspection preparation is significantly reduced, and the detection error can be reduced to perform the highly accurate detection.

Further, according to the present embodiment, instead of directly photographing the inspection target portion and performing image processing, the reflected light of the inspection target portion is collected in one place by the light receiving optical fiber, and the light receiving optical fiber is collected. Since the end portion is imaged, there is no limitation to the resolution of the ITV camera or the number of pixels of the frame memory of the defect detection device as in the conventional case, and the imaging and the image of a plurality of inspection target parts of a small area scattered in a wide range are performed. Processing and processing can be performed at the same time. Moreover, according to the present embodiment, it is not necessary to repeat imaging and image processing for one inspection target site several times, and it is possible to simultaneously perform imaging and image processing scanning for a plurality of inspection target sites. ,
It is now possible to apply defect detection by image processing to inspection targets for which it was actually difficult to apply the defect detection method by image processing in the past, and at the same time improve inspection accuracy and shorten inspection time. can do.

For example, taking the above-mentioned inspection of the valve seat as an example, when the defect detection by the image processing is to be performed by the conventional method, the detection end is set for each valve seat,
It is necessary to perform operations such as photographing and image processing one part of one valve seat at a time, and repeating these operations for all valve seats. Therefore, in order to inspect one cylinder head, it is necessary to repeat the above-mentioned shooting and image processing operations several times as many as the number of valve seats, and the overall inspection time becomes extremely long. It was difficult to apply defect detection. On the other hand, according to this embodiment, it is possible to simultaneously perform operations such as photographing of the entire eight valve seats and image processing at the same time.
Since the inspection of one cylinder head can be completed by taking the image twice, it is possible to easily detect a defect by image processing, which has been difficult in the past.

Further, by applying the image processing to the defect detection as described above, it becomes possible to automate the defect detection, and it is possible to eliminate the individual difference of the inspector even in the visual inspection on the monitor screen. It is possible to perform accurate inspection. It should be noted that, also in the present embodiment, FIG.
By changing the frequencies of the illumination light and the reflected light to be detected in each inspection area as in the first embodiment, it is possible to prevent the influence of the reflected light from other inspection areas and further improve the defect detection accuracy. Is.

[0063]

According to the present invention as set forth in the claims, the inspection accuracy can be improved because the inspection of a plurality of inspection target sites scattered over a wide range as described above can be performed accurately in a short time. It has a common effect that it is possible to achieve both the reduction of inspection time and the inspection time at the same time.

[Brief description of drawings]

FIG. 1 is a diagram illustrating a first embodiment of the present invention.

FIG. 2 is a diagram showing a shape of an inspection target portion of a valve seat portion of the embodiment of FIG.

FIG. 3 is a perspective view showing an appearance of a detection end of the embodiment of FIG.

FIG. 4 is a diagram showing a configuration of a lighting device of the embodiment of FIG.

5 is a diagram showing a configuration of a light amount detection device of the embodiment of FIG.

FIG. 6 is a view showing a shape of an inspection target portion of a valve seat portion different from that in FIG. 2;

FIG. 7 is a perspective view showing the outer appearance of a detection end used in the second embodiment of the present invention.

FIG. 8 is a diagram showing a configuration of a lighting device used in a second embodiment of the present invention.

FIG. 9 is a diagram showing a filter array used in the illumination device of FIG.

FIG. 10 is a diagram showing a configuration of a light amount detection device used in a second embodiment of the present invention.

FIG. 11 is a diagram showing another configuration example of the detection end according to the second embodiment of the present invention, which is different from FIG.

FIG. 12 is a diagram illustrating a third embodiment of the present invention.

13 is a perspective view showing the outer appearance of the detection end of the embodiment of FIG.

14 is a cross-sectional view taken along the axis of the detection end of FIG.

FIG. 15: VV of FIG. 14, showing an array of optical fiber bundles
It is sectional drawing which followed the line.

FIG. 16 is a diagram showing the configuration of the illumination device of the embodiment of FIG.

FIG. 17 is a diagram showing the configuration of the light amount detection device of the embodiment of FIG.

FIG. 18 is a diagram showing an image pickup array of light receiving optical fiber ends from respective detection ends in the light amount detection device.

FIG. 19 is a diagram illustrating a state of a surface defect of a portion to be inspected, which appears on the end surface of the light receiving optical fiber.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Detection end 2 ... Illumination optical fiber 3 ... Receiving optical fiber 4 ... Holder 10 ... Light amount detection device 20 ... Defect detection device 30 ... Illumination device 14, 33 ... Filter array 50 ... Engine cylinder head 54, 55, 56 ... Valve seat inspection target area

Claims (6)

[Claims] 1. A detection end is formed by integrally bundling one ends of a plurality of illumination optical fibers and a plurality of light receiving optical fibers, respectively.
The detection end is made to face the inspection target portion in close proximity, and an end portion of each of the illumination optical fibers opposite to the detection end is connected to a light source, and inspection is performed from the detection end via each of the illumination optical fibers. The illumination light is supplied to the target site, and the end portion on the opposite side of the detection end of each of the light receiving optical fibers is connected to the light amount detecting means, and the reflected light at the inspection target site is detected at the detection ends of the respective receiving optical fibers. By detecting the intensity of the reflected light received by each light receiving optical fiber by the side end face by the light amount detecting means, the detection end side end face of each light receiving optical fiber of the defect of the surface of the inspection object part facing A surface defect detection method for determining the presence or absence. 2. The inspection target portion is divided into a plurality of regions, and illumination light having a different frequency is supplied to each region via the illumination optical fiber facing each region, and the light amount detection means The surface defect according to claim 1, wherein, of the reflected light received by each of the light receiving optical fibers, the intensity of the reflected light of the frequency of the illumination light supplied to the region where the respective light receiving optical fibers face each other is determined. Detection method. 3. A plurality of the detection ends are formed, and the detection ends are arranged in close proximity to different inspection target portions at the same time so as to face each other, and a light receiving optical fiber from each of the detection ends is one light amount detecting means. 3. The surface defect detection method according to claim 1, wherein the presence or absence of surface defects at a plurality of inspection target portions are simultaneously determined by simultaneously determining the intensities of the reflected light received by the respective light receiving optical fibers. 4. A detection end, which is formed by bundling one ends of a plurality of illumination optical fibers and a plurality of light reception optical fibers integrally, and which is arranged to face the inspection target portion and faces each other, and each of the illumination optical fibers. One end on the opposite side of the detection end is connected, a light source that supplies illumination light from the detection end to the inspection target site via the illumination optical fiber, and on the opposite side of the detection end of each of the light receiving optical fibers. One end is connected, and the light amount detecting means for detecting the intensity of the reflected light received by the detecting end of the light receiving optical fiber, and the detection of each light receiving optical fiber based on the light intensity detected by the light amount detecting means A surface defect detecting device, comprising: defect detecting means for determining the presence / absence of a defect on the surface of the inspection target portion whose ends face each other. 5. The inspection target part is divided into a plurality of regions, and the light source includes means for supplying illumination light of a different frequency for each region via an illumination optical fiber facing the respective regions, The light amount detection means detects the intensity of the reflected light having a frequency equal to the frequency of the illumination light supplied to the region where the respective light receiving optical fibers face each other, out of the reflected light received by each of the light receiving optical fibers. Item 4. The surface defect detection device according to item 4. 6. A plurality of the detection ends, and a single light amount detection means to which the optical fibers for receiving light from the respective detection ends are connected, wherein the respective detection ends are in close proximity to different inspection target portions at the same time. Are arranged facing each other, the light amount detection means simultaneously detects the intensity of the reflected light received by the light receiving optical fibers of all the detection ends, the defect detection means based on the light intensity detected by the light amount detection means, The surface defect detection device according to claim 4 or 5, wherein the presence or absence of a defect on the surface of each inspection portion where the detection ends of the respective light-receiving optical fibers face each other is determined at the same time.