JP2009128230A - Method of evaluating spherical object diameter inequality, sorting method, and sorter of spherical object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of quickly, accurately and inexpensively evaluating diameter inequality of a spherical object having a high production speed with the production speed, and to provide a sorting method and a sorter of the spherical object using its evaluating method. <P>SOLUTION: The method of evaluating spherical object diameter inequality includes: mounting the spherical object 1 on a small container 9; continuously photographing the outer shape of the spherical object 1 of a swing state with a camera 5 from a constant direction five to ten times; finding the maximum diameter of each image; next, finding the maximum value (diameter maximum value) of the maximum diameter through all images; and calculating diameter inequality from correlation of the diameter maximum value and the diameter inequality of the spherical object 1 obtained previously. In addition, the method sorts quality of the spherical object 1 in a standard value of the diameter inequality by using the diameter inequality obtained above. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for evaluating a non-diameter, which is a difference between a maximum value and a minimum value of a diameter of a spherical body slightly distorted from a true sphere, a method for selecting a spherical body based on a standard value of non-diameter, and a sorting apparatus. In particular, the present invention relates to an evaluation method, a sorting method, and a sorting apparatus suitable for a small-diameter glass sphere (hereinafter referred to as a glass sphere) used as a glass material for molding an aspheric lens or a communication lens.

  One of the characteristics required for glass spheres (diameters of about 2 mm to 15 mm) used as glass materials for molding aspherical lenses and communication lenses is sphericity. As a method for quantitatively expressing the sphericity, a non-diameter that is the difference between the maximum value and the minimum value of the diameter is used. Glass spheres with diameters exceeding the standard value have a problem in lens molding, and need to be excluded as defective products. Incidentally, the standard value of the same diameter of the glass spheres according to the present invention is, for example, about 300 μm.

Conventionally, there are two methods for determining the unequal diameter: (1) a method of measuring the maximum and minimum values of the diameter of a glass sphere under a measuring optical microscope and calculating the difference; There was a method of rolling and estimating from the rolling condition. As a further advanced method, there has been proposed (3) a method of calculating a difference in diameter by measuring by rotating a glass sphere under a measurement optical microscope incorporating an image processing device (for example, Patent Document 1).
JP 2000-292138 A

  In recent years, the production speed of continuously produced glass spheres has been increased to 30 or more per minute, and a 100% online inspection of the same speed as production is required. A simple off-line 100% manual microscopic inspection is not possible to perform a rapid inspection and the manufacturing cost is high. In addition, a sorting method using a difference in rolling method on an inclined plate depending on the size of diameters is known, but when actually tried, glass spheres with diameters exceeding 300 μm are completely eliminated as defective products. If it tries to do so, about 50% of non-defective products having a diameter difference of 300 μm or less will be mixed into the defective product side, which is not practical.

  The measuring method introduced in Patent Document 1 is a method of measuring and measuring 36 images by rotating a container containing glass balls under an optical microscope by 360 ° in 10 ° increments. However, it takes a lot of time and there is a difficulty in quickness.

  The present invention has been made in view of the above-mentioned problems of the prior art, and uses a method for evaluating the diameter disparity of a spherical body having a high production rate quickly, accurately and inexpensively according to the production rate, and its evaluation method. It is an object of the present invention to provide a sorting method and sorting apparatus for spherical bodies.

  As a result of intensive studies to achieve the above object, the inventor of the present application has determined that the glass spheres have a flat bottom in order to quickly and accurately evaluate the irregular diameter of the continuously produced glass spheres according to the production speed. The outer shape of the glass sphere placed on a small container and oscillating is photographed continuously 5 to 10 times with a camera from a certain direction. First, the maximum diameter for each image is obtained, and then the entire diameter is obtained through all images. Invented a method to calculate the unequal diameter from the correlation between the maximal diameter and the unequal diameter of glass spheres of that dimension that have been experimentally obtained in advance. .

  That is, the method of evaluating the diameter of the spherical body of the present invention is to measure the maximum diameter of the swinging spherical body a plurality of times from a certain direction, and to determine the maximum value among the measured values of the plurality of maximum diameters. The maximum diameter value of the body is used, and the non-uniform diameter of the spherical body is calculated based on a known correlation between the maximum diameter value and the non-diameter diameter.

  In addition, the outer shape of the oscillating glass sphere is photographed continuously 5 to 10 times with a camera from a certain direction, the minimum diameter for each image is obtained, and then the minimum of the minimum diameter is obtained for all images. Invented a method of calculating a value difference (referred to as a diameter minimum value), and calculating the diameter disparity from the correlation between the diameter minimum value and the diameter disparity of a glass sphere of the size obtained in advance.

  That is, in the method for evaluating the diameter of spherical bodies of the present invention, the minimum diameter of the swinging spherical body is measured a plurality of times from a certain direction, and the minimum value among the measured values of the plurality of minimum diameters is measured. The minimum diameter value of the body is used, and the non-uniform diameter of the spherical body is calculated based on the known correlation between the minimum diameter value and the non-diameter diameter.

  In addition, the method for evaluating the diameter of a spherical body of the present invention is characterized in that the number of measurements of the maximum diameter or the minimum diameter of the spherical body is 5 to 10 times. If the number of times of photography is less than 5 times, the measurement accuracy is lowered, and if the number of times of photography exceeds 10 times, the measurement time becomes longer. In the present invention, the number of photographing is preferably 5 to 10 times in consideration of the balance between measurement accuracy and measurement time.

  Moreover, the evaluation method for the diameters of spherical bodies of the present invention is characterized in that the spherical body is a glass spherical body. Glass spheres for lenses are continuously produced at high speed, and 100% inspection is required at the same speed as production, and the present invention is suitable for evaluation of such glass spheres with different diameters.

  Furthermore, based on the diameter difference obtained in this way, a sorting method for eliminating glass spheres having a diameter difference exceeding the standard value defining the upper limit and a sorting apparatus using the sorting method were invented.

  That is, the method for selecting a spherical body according to the present invention is characterized in that a spherical body having a diameter difference exceeding a standard value is excluded based on the diameter difference obtained by the above-described evaluation method for diameter difference.

Further, the spherical body sorting apparatus of the present invention is a receiving cup having a flat support surface of a spherical body that is a body to be sorted, and a regulating wall around it,
Supply means for supplying the spherical body to the receiving cup;
Photographing means for photographing an image of the spherical body in the receiving cup;
The photographed image is processed, the diameter unequal diameter of the sphere is calculated by the unequal diameter evaluation method according to any one of claims 1 to 4, and the quality of the sphere is determined based on the standard value of the unequal diameter. An image processing apparatus that performs determination and outputs the pass / fail determination result;
And a sorting mechanism that sorts the spherical body into a non-defective product or a defective product according to the quality determination result.

  It is now possible to increase the production volume because it is possible to quickly and accurately perform on-line evaluation of diameters of spherical bodies that are continuously produced and sorting operations based on standard values of diameters that are the same as the production speed. Sorting costs could be reduced by automating sorting operations.

  By controlling the mass of the softened glass mass called gob that is supplied to the glass forming equipment, and by selecting the mass of the glass spheres after molding, the mass of the glass spheres can be accurately adjusted. In other words, when the volume of the glass sphere is controlled within a sufficiently narrow range, it is considered that the maximum diameter increases (or the minimum diameter decreases) as the distortion from the true sphere increases. . The point of the present invention is that the maximum diameter (or minimum diameter) is obtained by utilizing such a correlation between the diameter undulation and the maximum diameter (or minimum diameter) of glass spheres obtained experimentally in advance. It is to calculate the diameter disparity by measuring.

  As an example, the maximum diameter value and the minimum diameter value and the non-uniform diameter of 70 glass globules are accurately measured under an optical measuring microscope in FIG. 1. The non-diameter is plotted on the horizontal axis, and the maximum and minimum diameter values are plotted on the vertical axis. Shows the plotted graph. As shown in FIG. 1, there is a correlation between different diameters, maximum diameter values, and minimum diameter values. By utilizing this correlation, it is possible to estimate a highly accurate diameter difference from the measured value of the maximum diameter value (or minimum diameter value) of the glass sphere without measuring the diameter difference of the glass sphere itself. Since the measurement with the same diameter takes much time compared with the measurement of the maximum diameter value or the minimum diameter value, the measurement time saving effect by the invention of this method is very large.

  In the case of FIG. 1, if the glass sphere is a true sphere with no diameter difference, the diameter is 6.45 mm. Since the actual glass spheres have a diameter difference of about 80 μm to 380 μm, the maximum diameter varies from 6.47 mm to 6.66 mm, and the minimum diameter varies from 6.27 mm to 6.41 mm. The variation is not random, and a linear correlation is seen as shown. The standard value of 300 μm with the same diameter corresponds to 6.60 mm for the maximum diameter value and 6.30 mm for the minimum diameter value. Therefore, if the maximum diameter is 6.60 mm and the minimum diameter is 6.30 mm, the diameter is selected. This is equivalent to sorting the difference between 300 μm. In the actual sorting operation of the glass spheres, it is preferable to consider the correlation error and sort the calculated values having the same diameter with a margin of about 50 μm so that the defective products are not mixed in the non-defective products after the sorting.

  As shown in Fig. 1, the correlation between the unequal diameter and the maximum diameter and minimum diameter is determined if the glass sphere material, target size, production line, etc. are determined. You can get it. The method of measuring the maximum diameter and minimum diameter developed by the present inventor, which will be described later, is simple and quick, so it can be easily automated, and it can be automatically measured online by combining continuous production of glass spheres and speed (also referred to as an index). Automatic sorting work is possible.

  Next, a method and apparatus for measuring the maximum diameter of glass spheres produced continuously by the inventors of the present application, a measuring apparatus, and a sorting apparatus for different diameters will be described. FIG. 2 shows a configuration example of a glass sphere diameter maximum value measuring device and a glass sphere sorting device directly connected thereto. The glass sphere 1 is supplied from the supply chute 2 to the receiving cup 9 of the turntable 3, and is sent to the photographing location (directly under the camera 5) by rotating the turntable 3 by 90 °. The turntable 3 temporarily stops at the photographing position, but the glass ball 1 in the receiving cup 9 does not stop for a short time and continues to swing. The receiving cup 9 is made of a translucent material so that a transmission image of the glass sphere 1 can be easily taken, and illumination (not shown) is provided below the shooting position (below the receiving cup 9). . Further, a flat support surface is provided on the inner bottom surface of the receiving cup 9 so that the glass sphere 1 can freely swing, and a restriction wall is provided around the glass cup so that the glass sphere 1 does not protrude from the photographing range 5 a of the camera 5. 9a. The glass sphere 1 oscillating at the photographing location is photographed continuously 5 to 10 times from the vertical direction with the camera 5, and the maximum diameter value is obtained by the image processing device 6 from the obtained 5 to 10 images. Ask. Note that the shooting direction from the camera 5 is preferably the vertical direction in order to increase the measurement accuracy. However, if it is difficult to install the camera 5 in the vertical position due to mechanical limitations, the shooting direction is not limited to the vertical direction, and shooting may be performed from an oblique direction. Good.

  Next, based on the correlation between the diameter difference and the maximum diameter value obtained in advance as shown in FIG. 1, the diameter difference is calculated from the measured maximum diameter value, and compared with the standard value for the diameter difference, the quality is determined. To do. The glass sphere 1 that has been photographed by the camera 5 is rotated to the take-out position by the turntable 3 and transferred to the take-out chute 4 to be supplied to the sorting mechanism 7. Selected. When selecting using the minimum diameter value, the “maximum diameter value” in the above description is read as “minimum diameter value”.

FIG. 3 shows the principle of measuring the maximum diameter value from the captured image of the glass sphere 1 by the camera 5. FIG. 3A shows the case where the glass sphere 1 is stationary. At this time, the maximum diameter D ₀ (equal to the maximum diameter value) can be obtained by one shooting. However, since the glass sphere 1 does not stand still in a short time in actual measurement, an image having the maximum diameter D ₀ can be obtained by one shooting. It is extremely rare to be able to shoot. Actually, as shown in FIG. 3 (b), the glass sphere 1 continues to swing randomly during photographing. Therefore, a plurality of images are taken and the maximum diameter is obtained for each image. If the number of photographing is small, the measurement accuracy is low, and if the number of photographing is large, the measurement time is long. The number of times of photographing is appropriately 5 to 10 times considering the balance. Since one maximum diameter is obtained for one image, the same maximum diameter as the number of photographing is obtained. Next, all the maximum diameters are compared, and the maximum of them is calculated as the maximum diameter value. Since the glass sphere 1 is oscillating, the true maximum diameter cannot be measured accurately, but it was measured from various directions (the shooting direction from the camera 5 is constant, but the glass sphere 1 changes direction randomly). It is considered that some of the maximum diameters are very close to the true maximum diameter, and the maximum value among the maximum diameters is considered as the maximum diameter value. This maximum diameter value is probably slightly smaller than the true maximum diameter value, but it has been confirmed that there is sufficient accuracy for use in sorting the glass spheres 1. In other words, an image very close to the image having the maximum diameter D ₀ can be captured in a short time by actively swinging the glass sphere 1 and photographing the oscillating glass sphere 1 a plurality of times. Can do.

The method for obtaining the maximum diameter described above will be described with reference to FIG. 3B. The maximum diameter D _{1 in} the first image, the maximum diameter D _{2 in} the second image, and the third image Then, each maximum diameter is obtained for each image, such as maximum diameter D ₃ . Each of the maximum diameters D ₁ , D ₂ , D ₃ ,... Is slightly different because the direction of the glass sphere 1 at the time of photographing is different, so that the largest one is obtained by comparing them. For example, the maximum diameter D ₂ of the second image to the maximum diameter D ₂ and the diameter maximum Tara greatest. Then fit the value D ₂ on the vertical axis of FIG. 1, we obtain the value of the corresponding diameter unequal by a correlation straight line, performs quality determination by comparing the standard value (e.g., 300 [mu] m).

Next, the principle of measuring the minimum diameter value of the glass sphere 1 from the image taken by the camera 5b will be described with reference to FIG. When measuring the minimum diameter, the glass sphere 1 placed in front of the backlight 14 is photographed from the horizontal direction. FIG. 4A shows a case where the glass sphere 1 is stationary. At this time, the minimum diameter d ₀ (equal to the minimum diameter value) can be obtained by one shooting, but in reality this is extremely rare because the glass sphere 1 does not stand still in a short time. Actually, as shown in FIG. 4B, the glass sphere 1 continues to swing randomly during the photographing. Therefore, a plurality of images are taken and the minimum diameter is obtained for each image. An appropriate number of times of photographing is 5 to 10 times. Since one minimum diameter is obtained for one image, the same minimum diameter as the number of photographing is obtained. Next, all the minimum diameters are compared, and the smallest one is considered as the minimum diameter value. That is, since the glass sphere 1 is oscillating, the true minimum value cannot be measured accurately, but the minimum value among the minimum diameters is considered to be very close to the true minimum value. Although this minimum diameter value is considered to be slightly larger than the true minimum diameter value, it has been confirmed that there is sufficient accuracy for use in the selection of the glass spheres 1. Note that the shooting direction from the camera 5b is preferably the horizontal direction in order to increase the measurement accuracy. However, if it is difficult to install the camera 5b at the horizontal position due to mechanical limitations, the shooting direction is not limited to the horizontal direction, and shooting may be performed from an oblique direction. Good.

The method for obtaining the minimum diameter described above will be described with reference to FIG. 4B. The minimum diameter d _{1 in} the first image, the minimum diameter d _{2 in} the second image, and the third image Then, each minimum diameter is obtained for each image, such as minimum diameter d ₃ . Each of the minimum diameters d ₁ , d ₂ , d ₃ ,... Is slightly different because the direction of the glass sphere 1 at the time of shooting is different, so that the smallest one is obtained by comparing them. For example the minimum diameter d ₂ of the second image to the minimum diameter d ₂ and the diameter minimum Tara smallest. Then fit the value d ₂ on the vertical axis of FIG. 1, we obtain the value of the corresponding diameter unequal by a correlation straight line, performs quality determination by comparing the standard value (e.g., 300 [mu] m).

FIG. 5 is an explanatory diagram of a method for obtaining the maximum diameter D _n from the nth image of the glass sphere 1. When the glass sphere 1 is photographed with the camera 5, a transparent image (shadow) 1a of the glass sphere 1 with a bright background and a dark glass sphere 1 portion is obtained in the photographing range 5a of the camera 5 by back lighting from below. . Since the brightness of the transmission image 1a of the glass sphere 1 changes greatly on the outer periphery of the glass sphere 1, the diameter can be obtained clearly. The diameter measurement line 13 is turned around to obtain the largest value of the diameter, and this value is set as the maximum diameter D _n of this image. In addition, since it can carry out by the same operation also when calculating | requiring the minimum diameter of the glass sphere 1 from an image, the description is abbreviate | omitted.

With reference to FIG. 6, the flow of evaluation and selection of glass spheres with different diameters will be described.
(1) Confirm that the glass ball 1 is at the measurement position (the shooting range 5a of the camera 5).
(2) The glass sphere 1 is photographed, and the maximum diameter (or minimum diameter) for the image is obtained by the method shown in FIG.
(3) The glass sphere 1 is photographed a set number of times (usually 5 to 10 times).
(4) The maximum diameters D ₁ , D ₂ , D ₃ ,... (Or the minimum diameters d ₁ , d ₂ , d ₃ ,...) Of each time are compared, and the largest one is set as the maximum diameter value (or The smallest is the minimum diameter).
(5) The non-diameter is calculated using a correlation graph between the maximum diameter (or minimum diameter) and the non-diameter as shown in FIG.
(6) If the difference in diameter is less than or equal to the standard value, the glass ball 1 is determined as a non-defective product 11, and if it exceeds the standard value, it is determined as a defective product 12.

  Next, examples and comparative examples of non-diameter selection of glass spheres will be described with reference to Table 1. Example 1 is a result of sorting glass spheres having a target diameter of 8.45 mm at a rate (index) of 30 pieces / minute using the sorting method of the present invention. (The non-defective product has a diameter difference of 300 μm or less. However, in consideration of the correlation error as shown in FIG. 1, the calculated value of the same diameter is used so that defective products are not mixed in the non-defective product after sorting. On the other hand, a non-defective product having a calculated diameter of 250 μm or less was selected as a non-defective product with a 50 μm margin. Example 2 is a result of sorting glass spheres having a target diameter of 6.45 mm at a rate of 33 pieces / minute using the sorting method of the present invention, and the mixing ratio of non-defective products to poorly sorted products was 15%. It was. Example 3 is a result of sorting glass spheres having a target diameter of 6.30 mm at a rate of 33 pieces / minute using the sorting method of the present invention, and the mixing ratio of non-defective products to poorly sorted products was 15%. It was.

  On the other hand, the comparative example is a result of sorting glass spheres with a target diameter of 6.30 mm at a rate of 30 pieces / minute using a conventional inclined plate sorting method, and mixing non-defective products into poorly sorted products. The rate was 50%. The tilted plate selection method of the comparative example was not practical because the yield of non-defective products was excessive and the production yield of small glass balls deteriorated.

  The present invention can be applied to volume-controlled resins, ceramics, and other spherical bodies in addition to the glass globules of the above embodiments.

The graph which shows the relationship between the diameter difference of a glass small sphere, the diameter maximum value, and the diameter minimum value. The block diagram of the measuring device of the diameter maximum value of a glass small ball, and a non-diameter sorter. The principle figure which measures a diameter maximum value from the picked-up image of a glass ball. The principle figure which measures the diameter minimum value from the picked-up image of a glass ball. Explanatory drawing of the method of calculating | requiring the maximum diameter from the image of a glass sphere. The flowchart which shows the flow of calculation and selection of the same diameter of a glass sphere.

Explanation of symbols

1 Glass sphere (spherical body)
DESCRIPTION OF SYMBOLS 1a Transparent image of glass sphere 2 Supply chute 3 Turntable 4 Takeout chute 5 Camera 5a Camera photographing range 5b Camera 6 Image processing device 6a Pass / fail judgment result 7 Sorting mechanism 9 Receiving cup 9a Receiving cup regulating wall 11 Non-defective glass sphere 12 Defective glass sphere 13 Diameter measurement line 14 Back light

Claims (6)

  The maximum diameter of the swinging sphere is measured a plurality of times from a certain direction, and the maximum value among the measured values of the plurality of maximum diameters is the maximum diameter of the sphere, A method for evaluating the non-uniform diameter of a spherical body, wherein the non-uniform diameter of the spherical body is calculated based on the known correlation.   The minimum diameter of the swinging sphere is measured a plurality of times from a certain direction, and the minimum value among the measurement values of the plurality of minimum diameters is the minimum diameter of the sphere, A method for evaluating the non-uniform diameter of a spherical body, wherein the non-uniform diameter of the spherical body is calculated based on the known correlation.   The method for evaluating the spherical bodies with different diameters according to claim 1 or 2, wherein the number of measurements of the maximum diameter or the minimum diameter of the spherical bodies is 5 to 10 times.   The said spherical body is a glass spherical body, The evaluation method with the same diameter of the spherical body in any one of Claims 1-3 characterized by the above-mentioned.   5. A method for selecting a spherical body, characterized in that a spherical body having a diameter difference exceeding a standard value is excluded based on the diameter difference obtained by the non-diameter evaluation method according to claim 1. . A receiving cup having a flat support surface for supporting a spherical body to be selected, and a regulating wall around it,
Supply means for supplying the spherical body to the receiving cup;
Photographing means for photographing an image of the spherical body in the receiving cup;
The photographed image is processed, the diameter non-uniformity of the spherical body is calculated by the non-diameter evaluation method according to any one of claims 1 to 4, and the spherical body of the spherical body is calculated based on a standard value of the non-diameter. An image processing apparatus that performs pass / fail determination and outputs the pass / fail determination result;
A spherical body sorting apparatus comprising: a sorting mechanism that sorts the spherical body into a non-defective product or a defective product according to the quality determination result.

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