JPH06249786A - Inspection method for pellet edge - Google Patents

Abstract

PURPOSE:To inspect the edge of a pellet at high speed by a method wherein a histogram for the brightness of the image, of the edge in a pellet, which has been picked up is formed, a feature value is extracted and the feature value is compared with a statistical feature value in a histogram which has been extracted from many standard pellets in advance. CONSTITUTION:Rays of light from a fiber light source 220 are converged through a plano-concave lens 223d, and they are changed to parallel rays. The parallel rays are passed through a perforated lens 223e and a half mirror, and both edges of a pellet P are irradiated with the parallel rays. The rays which are passed through the central opening part and the peripheral edge part of the lens 223e are changed respectively to parallel rays and converged rays, and a recessed part PA at the edge of the pellet P is irradiated at uniform brightness. The image of the recessed part PA which has been picked up by a CCD camera 232 does not cause a shadow, and only a flaw appears as black. The image is taken into an image processor. A histogram for the brightness of inspection regions is formed. Its feature value is compared with a statistical feature value, for many normal products and defective products, which has been extracted in advance. Whether they are good or not and whether they are to be held are decided. Thereby, the image is processed easily, and the recessed part PA can be inspected quickly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pellet end face inspection method for picking up an image of the end face of a pellet having a concave portion formed at the center of the end face and judging the quality of the end face of the pellet based on the obtained image.

[0002]

2. Description of the Related Art Conventionally, when a parallel light beam is applied to the end surface of a pellet having a spherical recess (dish) formed in the center of the end surface, the peripheral portion of the recess becomes dark, and the obtained image is When digitized, it becomes difficult to distinguish from defects such as chips.

[0003]

In order to solve this problem, Japanese Laid-Open Patent Publication No. 1-136053 proposes a method for detecting a defect by adding correction data from a standard image and binarizing it. ing. This defect inspection method exerts its effect within a range in which it is ensured that the sample is imaged like a standard image, but in reality, there are many problems that do not fall within such a range. is there. Further, since the load on the image processing is large, the processing takes time, and there is a problem that the end face inspection of the pellet cannot be performed at high speed.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to smoothly and surely inspect the end surface of a pellet having a recess formed in the center of the end surface. The load on image processing can be reduced,
An object of the present invention is to provide a pellet end face inspection method capable of automatically inspecting at high speed.

[0005]

In order to achieve the above object, according to claim 1 of the present invention, an image of an end face of a pellet having a recess formed in the center of the end face is imaged, and based on the obtained image. A pellet end face inspection method for determining the quality of the end face of a pellet, taking a brightness histogram for the imaged end face image of the pellet, extracting the feature value of this histogram, and the feature value of the extracted histogram The state of the end surface of the pellet is determined by comparing with the statistical characteristic values of the histogram extracted in advance for a large number of typical standard pellets. Also,
According to a second aspect of the present invention, when the end face of the pellet is imaged, the end face of the pellet is irradiated with parallel rays, and
The brightness of the end surface image of the pellet is made uniform by irradiating the end surface concave portion of the pellet with the focused light beam. Further, claim 3 of the present invention relates to the pellets retained in the determination by the histogram,
Binarizing the captured end face image with reference to the histogram feature value, performing connectivity identification and pixel number calculation for this binarized image, and determining pass / fail of the end face of the pellet based on this result Is. Claim 4 of the present invention
When imaging the end surface of the pellet, the pellet is housed in the housing groove formed in the outer edge of the rotating disk that rotates intermittently, and both end surfaces of the pellet are sequentially imaged.
The pellets determined to be unacceptable based on the imaged end face image are discharged from the pellet conveying path.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a side view showing an example of a pellet handling section 10 showing an embodiment of the present invention. In this figure, reference numeral 1 is a rotary disk. A large number of V-grooves 2 for accommodating the pellets P are formed on the outer edge of the rotary disc 1, and the pellets P are fed from the carry-in chute 3 into the V-grooves 2 of the rotary disc 1. Has been done. Further, an arc-shaped guide surface 4 for guiding the pellet P is provided outside the rotary disc 1, and a pellet P that is connected to the guide surface 4 and discharges the pellet P determined to be defective by the end face inspection. A sorting unit 5 and a carry-out chute 6 for carrying out the acceptable pellets P are provided.
Then, the pellet selecting section 5 discharges the defective pellets P downward by rotating the rotator 7 provided rotatably in the vertical direction downward. Further, a pusher 8 for holding the pellet P accommodated in the V groove 2 is provided above the rotating disk 1 so as to be vertically rotatable.

As shown in FIG. 2, a pellet end face inspection device 20 of the present invention is provided on both sides of the pellet handling section 10. In these pellet end face inspection devices 20, an illumination means 22 and an image pickup means 23 are installed on a mounting member 21, and the image pickup means 23 is provided.
The image analysis processing device is connected to. And
The illuminating means 22 includes a fiber light source 220, a light source lens 221, a hood 222, a lens barrel 223, and a half mirror box 224 arranged vertically in a line, and the pellet handling on the side of the half mirror box 224. Hood 22 extending to the end surface of pellet P of portion 10
5 are arranged. The lens barrel 223 has four barrel-shaped lens set screws 223b inside the barrel body 223a.
And one cylindrical tip protrusion 223c are screwed so as to be vertically movable, and the plano-convex lens 223d and the perforated lens 22 are attached to the lens set screws 223b.
3e is clamped. In addition, the half mirror box 22
4 has a half mirror 224 inclined at 45 degrees with respect to the optical axis of the light beam emitted from the fiber light source 220.
a is stored. Further, the image pickup means 23 is provided with a camera lens 230 on the side of the half mirror box 224.
The intermediate ring 231 and the CCD camera 232 are arranged.

When the end surface of the pellet P is inspected by using the pellet end surface inspection apparatus having the above-mentioned structure,
First, the pellet P is supplied from the carry-in chute 3 onto the V groove 2 of the rotating disk 1 which is rotating intermittently. Then, the pellet P accommodated in the V groove 2 of the rotating disk 1 is placed at the predetermined position P.
1 and P2, images of both end faces of the pellet P are captured by the pellet end face inspection device 20 arranged so as to face both end faces of the pellet P. That is, the light rays emitted from the fiber light source 220 are focused by the plano-convex lens 223d of the lens barrel 223 through the light source lens 221 and the inside of the hood 222 to become parallel light rays, and these parallel light rays are used as the perforated lens 223e. Both end surfaces of the pellet P housed in the V groove 2 of the rotating disk 1 is irradiated with the light passing through the inside of the half mirror 224a and the hood 225. In this case, the parallel light rays that have passed through the central opening of the perforated lens 223e are directly subjected to the pellet P.
Is irradiated to the entire end face of the lens and the perforated lens 223e
The light rays that have passed through the peripheral portion of the above are converged and applied to the concave portion PA at the center of the end surface of the pellet P shown in FIGS. As a result, as shown in FIG. 10, the brightness of the recess PA of the pellet P can be made uniform (in FIG. 10, the two-dot chain line indicates the brightness when only parallel rays are applied to the entire end surface of the pellet P). Is shown).

In this state, the CCD camera 23
By imaging the end surface of the pellet P by 2 as described above, the obtained image is clear and the recess PA on the end surface of the pellet P is not shaded, and only the defect appears black. Next, the obtained image is sent to the image analysis processing device, and in this image analysis processing device, only the inspection area of the multi-valued image is taken out, and the brightness histogram is taken in this mask image. Then, the characteristic value of this histogram (brightness with the largest number of pixels, maximum and minimum brightness based on that brightness, brightness of mountains and valleys and number of pixels)
Is compared with the statistical feature values of a large number of typical normal products, defective products, and rejected products that have been extracted in advance, and pass / fail or suspension is determined. That is, the above histogram is obtained, for example, from the state of the end surface of the normal pellet P shown in FIG.
In a state in which the sintered powder or the like shown in 2 adheres to the end surface of the pellet P, a state in which a difficult-to-detect chip shown in FIG. , And each has a characteristic waveform, which can be used to determine the end surface of the pellet P.

Further, with respect to the reserved products for which the pass / fail judgment cannot be made by the histogram, the image and the histogram characteristic value are transferred to another processing board through the bus line, and in parallel, the histogram characteristic value is referred to to determine the proper value. The binarization value is determined and binarized by this value, the outside of the inspection target part of this binarized image is masked at the same level as the defect, and the connectivity identification of the obtained normal level image (for example,
After performing (a) and (b) discrimination in FIG. 14), the number of pixels of only the normal portion a is calculated, and the result is passed to the determination unit. Then, in this determination unit, the result of the above-mentioned histogram and the result of the binarized image are combined to determine whether the pellet P is acceptable or not. For the pellets P determined to be unacceptable, the rotator 7 of the pellet selection unit 5 is rotated to discharge downward.

[0012]

As described above, according to the first aspect of the present invention.
Is a pellet end face inspection method for imaging the end face of a pellet in which a concave portion is formed in the center of the end face, and determining the quality of the end face of the pellet based on the obtained image. Take the brightness histogram for the image, extract the feature value of this histogram, the extracted feature value of the histogram, and the statistical feature value of the histogram extracted for a number of typical standard pellets in advance. Since the state of the end surface of the pellet is determined by comparing the above, image processing can be easily performed, and the end surface of the pellet can be smoothly and quickly inspected. Further, according to claim 2 of the present invention, when the end face of the pellet is imaged, the end face image of the pellet is obtained by irradiating the end face of the pellet with a parallel light beam and irradiating the focused light beam to the end face concave portion of the pellet. Therefore, it is possible to prevent the shadow of the recess from appearing in the end face image of the pellet, and to image only the defect in black. Further, claim 3 of the present invention
For the pellets held in the determination by the above histogram, the captured end face image is binarized with reference to the histogram feature value, the connectivity identification and the pixel number calculation are performed on the binarized image, and the result Since it is to determine the acceptance of the end surface of the pellet based on
By performing the determination based on the binarized image only on the suspended pellets, the load on the image processing can be reduced, and the inspection can be automatically performed at high speed. According to claim 4 of the present invention, when imaging the end surface of the pellet, the pellet is housed in a housing groove formed in an outer edge portion of a rotating disc that rotates intermittently, and both end surfaces of the pellet are sequentially imaged. Since the pellet determined to be unacceptable based on the captured end face image is discharged from the pellet conveying path, the end face of the pellet which is accommodated in the accommodating groove of the rotating disk and is stationary in a stable state. Can be imaged, a good end face image can be obtained, and pellets for which the pass / fail judgment has been completed can be easily selected.

[Brief description of drawings]

FIG. 1 is a side view showing an example of a pellet handling unit.

FIG. 2 is a front view showing an embodiment of the present invention.

3 is a front view showing one of the pellet end face inspection devices of FIG. 2. FIG.

FIG. 4 is a side view of FIG.

FIG. 5 is a bottom view of FIG.

FIG. 6 is an explanatory diagram showing an embodiment of the present invention.

FIG. 7 is a cross-sectional view showing an illumination unit.

FIG. 8 is an explanatory diagram showing a state of light rays.

FIG. 9 is an explanatory diagram showing an end surface of a pellet.

10 is an explanatory diagram showing brightness along AB of FIG. 9. FIG.

FIG. 11 is a characteristic diagram showing a histogram of an end face in a normal state.

FIG. 12 is a characteristic diagram showing a histogram of an end face in a state where sintered powder or the like is attached.

FIG. 13 is a characteristic diagram showing a histogram of an end face having a chip.

14 is an explanatory diagram showing an end face image of FIG. 13. FIG.

[Explanation of symbols]

 P Pellet PA Recess 1 Rotating disk 2 V groove (accommodation groove) 5 Pellet sorter 20 Pellet end face inspection device 22 Illuminating means 23 Imaging means 223d Plano-convex lens 223e Perforated lens

Claims (4)

[Claims] 1. A pellet end face inspection method for picking up an image of an end face of a pellet having a concave portion formed at the center of the end face and determining the quality of the end face of the pellet based on the obtained image. The brightness histogram is taken for the end face image of the pellet, the feature value of this histogram is extracted, and the feature value of this extracted histogram and the statistical value of the histogram previously extracted for a number of typical standard pellets. A method for inspecting a pellet end face, comprising comparing the state of the end face of the pellet with a characteristic value. 2. When the end face of the pellet is imaged, the end face of the pellet is irradiated with a parallel light beam, and the focused light beam is irradiated onto the end face recess of the pellet.
The pellet end face inspection method according to claim 1, wherein the brightness of the end face image of the pellet is made uniform. 3. A method of binarizing an imaged end surface image of a pellet held in a determination by a histogram with reference to a histogram feature value, and performing connectivity identification and pixel number calculation on the binarized image, The pellet end face inspection method according to claim 1, wherein the acceptance / rejection of the end face of the pellet is judged based on this result. 4. When the end surface of the pellet is imaged, the pellet is housed in a housing groove formed in the outer edge portion of a rotating disk that rotates intermittently, and both end surfaces of the pellet are sequentially imaged and imaged. The pellet end face inspection method according to claim 1, wherein the pellet determined to be unacceptable based on the end face image is discharged from a pellet conveying path.