JPH1130509A - Image-processing and measuring method of casting sand and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image-processing and measurement method of a casting sand that can obtain accurate contour of the sand and background without being affected by the difference in the degree of transparency and color of the casting sand, by paying attention to the darkening phenomenon of a subject due to backlight seen in photography, putting the casting sand on a specific reflection plate, setting an image-processing camera at a right angle to the reflection plate, applying light in parallel with the light axis of the camera to the reflection plate and the casting sand from a light source, and receiving reflection light from the casting sand and the reflection plate for processing images. SOLUTION: In the image processing and measurement method of a casting sand by binarization processing, a casting sand A is put on a reflection plate 3 having light transmission property and a smooth surface, the image-processing camera 6 is set at a right angle to the reflection plate 3, light in parallel with the light axis of the image-processing camera 6, is projected from a light source 9 to the reflection plate 3 and the casting sand A, and reflection light from the casting sand A and the reflection plate 3 is received for processing images.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image processing and measuring method for molding sand by processing an image of the molding sand by a binarization process in order to evaluate the degree of polishing of the molding sand and measuring the characteristic amount. The law and its apparatus.

[0002]

2. Description of the Related Art Generally, foundry sand such as core sand used for casting is regenerated and reused. In this case, the molding sand is taken out after the mold is released, and the mass of the taken out molding sand is pulverized (disintegrated). Since the filling rate decreases when the foundry sand is angular, the sand is rubbed against each other to polish the foundry sand.However, in order to evaluate how much the foundry sand was polished in this polishing process, Sand measurement is required.

Therefore, as an image processing measurement method and an apparatus for performing the above-described molding sand measurement, for example, a configuration as shown in FIG. 10 can be considered. That is, a white paper 93 is laid on a table 92 of an XY stage 91, and a plurality of molding sands 94 are placed on the paper 93, while a stereoscopic microscope 96 and an optical system as an optical system are provided below a CCD camera 95 for image processing. A micro lens 97 is attached, the light from the light source 98 is projected on the molding sand 94 on the paper 93 via the annular ring illuminator 99, and the image captured by the CCD camera 95 is output to the image processing apparatus 100. , Means configured to be displayed on the display unit 101 as a monitor.

According to this configuration, first, the XY stage 91
To display the image of the casting sand 94 to be measured on the display unit 10.
1, the image is taken into the image processing apparatus 100 by key input, and then the binarization threshold value is compared while comparing the outline of the grayscale image and the outline of the binarized image so that they match. In this method, the computer in the image processing apparatus 100 recognizes the contour, and measures the aspect ratio (short side ÷ long side) as a feature amount.

However, such a measuring method and its apparatus have various problems as follows. That is, the ring light from the ring illuminator 99 described above is
4 and white paper 93, the incident light becomes a non-perpendicular oblique light, and the reflection surface (the surface of the paper 93 and the molding sand 94) is formed due to the uneven surface of the paper 93.
The light received from the CCD camera 95 is weakly diffused light.

For this reason, the obtained image is information on the color of the foundry sand 94, and the clarity of the contour between the foundry sand 94 and the paper 93 as its background depends on the color of the foundry sand 94. Since there are various types of sand such as black, brown, white, and translucent as the molding sand 94, the difference (contrast) between the luminance of the background (see the paper 93) and the luminance of the molding sand 94 is small depending on the color of the sand. Therefore, an accurate contour of the foundry sand 94 cannot be obtained, and for example, a background image 1 as shown in FIG.
02 and the sand image 103.

[0007] Further, the brightness of the sand, the brightness of the background, and the difference (contrast) between the two differ greatly depending on the color of the foundry sand 94, and it is difficult to set a binarization threshold value.
Reference) and the outline of the binarized image are compared so that the outline of the binarized image matches the outline, and the work of adjusting the binarization threshold has a long time, the loss time is large, and the measurement takes time. If the binarization threshold is fixed for the purpose of eliminating the above-mentioned loss time, there is a fatal problem in measurement that the grayscale image and the binary image do not match depending on the color of the molding sand 94. there were.

On the other hand, as described in JP-A-5-20428, an object to be measured is imaged by a video camera, and an image signal output from the video camera is subjected to binarization processing and mask processing to obtain an image of the object to be measured. A measuring method for measuring the number and area of particles has already been invented. Even if this technical concept is applied to an image processing and measuring method for molding sand having various colors and different degrees of transparency, the same problem as described above occurs.

[0009]

SUMMARY OF THE INVENTION The invention according to claim 1 of the present invention focuses on the phenomenon of darkening of an object due to backlight seen in photographing, and arranges a molding sand on a unique reflector to reflect the light. An image processing camera is arranged at right angles to the plate, and light parallel to the optical axis of this camera is projected from the light source to the reflector and the molding sand, and the reflected light from the molding sand and the reflecting plate is received to perform image processing. It is an object of the present invention to provide an image processing and measuring method of a molding sand that can obtain an accurate contour between the sand and the background without being affected by a difference in the transparency and color of the molding sand at all.

According to the invention of claim 2 of the present invention, in addition to the object of the invention of claim 1, by setting the above-mentioned reflecting plate to a glass plate, the glass plate has high reflectivity and a smooth surface. Has a large difference (contrast) between the brightness of the foundry sand and the brightness of the background (glass plate), so that a more accurate contour can be ensured. It is an object of the present invention to provide an image processing and measuring method for molding sand which is easy to perform.

According to a third aspect of the present invention, in addition to the object of the second aspect, by setting the thickness of the above-mentioned glass plate to be greater than the depth of focus of the camera, It is an object of the present invention to provide an image processing and measuring method for molding sand which is not adversely affected by an object such as a metal reflecting plate existing in an object.

According to a fourth aspect of the present invention, in addition to the object of the second aspect, a metal reflection plate is provided below the glass plate, so that a higher reflection of reflected light is achieved. It is an object of the present invention to provide an image processing and measuring method for molding sand in which the amount is obtained and the contrast is further improved.

According to a fifth aspect of the present invention, in addition to the object of the first aspect, the image processing detects the contour of the foundry sand so that the contour between the sand and the background can be reliably detected. It is an object of the present invention to provide an image processing and measuring method for foundry sand which can be detected at a time.

According to a sixth aspect of the present invention, in addition to the object of the fifth aspect, a threshold value for binarization is set based on the relationship between the foundry sand and the background, so that the disturbance is improved. An object of the present invention is to provide an image processing method for molding sand that is not easily affected by light and can perform accurate measurement.

According to a seventh aspect of the present invention, in addition to the object of the first aspect, the light source has a luminous intensity adjusting function so that it can cope with deterioration of a light source such as a halogen lamp. It is another object of the present invention to provide an image processing and measuring method for molding sand capable of performing highly accurate measurement.

According to an eighth aspect of the present invention, there is provided a glass plate having a light transmitting property and a smooth surface, on which casting sand is disposed, and a glass plate disposed at right angles to the glass plate. By providing an image processing camera, a light source that projects light parallel to the optical axis of the camera onto a glass plate and molding sand, and a metal reflecting plate disposed below the glass plate, the transparency of the molding sand and Regardless of the color difference, you can get accurate contours,
Another object of the present invention is to provide an image processing and measuring apparatus for molding sand in which the above-mentioned contrast is extremely large and a clear contour can be obtained.

According to a ninth aspect of the present invention, in addition to the object of the eighth aspect, the image processing detects the contour of the foundry sand to ensure the contour between the sand and the background. It is an object of the present invention to provide an image processing and measuring apparatus for molding sand that can be detected at a time.

[0018]

The invention according to claim 1 of the present invention relates to an image processing and measuring method for molding sand by binarization processing, wherein the casting sand is cast on a reflecting plate having a light transmitting and smooth surface. Arranging sand, arranging an image processing camera at right angles to the reflection plate, projecting light parallel to the optical axis of the image processing camera from the light source to the reflection plate and the molding sand, and from the molding sand and the reflection plate. It is an image processing and measuring method for molding sand for which image processing is performed by receiving reflected light.

According to a second aspect of the present invention, there is provided an image processing and measuring method for molding sand in which the reflecting plate is set on a glass plate, in addition to the configuration of the first aspect of the present invention. .

According to a third aspect of the present invention, there is provided an image processing and measuring method for molding sand in which the glass plate is set to a thickness deeper than the depth of focus of a camera, together with the configuration of the second aspect. There is a feature.

According to a fourth aspect of the present invention, there is provided an image processing and measuring method for molding sand in which a metal reflecting plate is disposed below the glass plate in combination with the configuration of the second aspect. It is characterized by.

According to a fifth aspect of the present invention, in addition to the configuration of the first aspect, the image processing is an image processing and measuring method of molding sand for detecting a contour of the molding sand. And

According to a sixth aspect of the present invention, in addition to the structure of the fifth aspect of the present invention, a molding sand for setting a threshold value for binarization in relation to the background of the casting sand is provided. It is an image processing measurement method.

According to a seventh aspect of the present invention, in addition to the configuration of the first aspect, the light source is an image processing and measuring method for molding sand having a luminous intensity adjusting function.

The invention according to claim 8 of the present invention is an image processing and measuring apparatus for molding sand by binarization processing, which has a light transmitting property and a smooth surface, and the molding sand is disposed thereon. A glass plate, an image processing camera disposed at right angles to the glass plate, and a light source for projecting light parallel to the optical axis of the image processing camera onto the glass plate and the molding sand. The present invention is characterized in that it is an image processing and measuring apparatus for molding sand in which a metal reflector is provided at a lower portion.

According to a ninth aspect of the present invention, in addition to the configuration of the eighth aspect, the image processing is a molding sand image processing and measuring apparatus for detecting a contour of the molding sand. And

[0027]

According to the first aspect of the present invention, casting sand is provided on the above-mentioned reflecting plate, and light parallel to the camera optical axis from the light source is applied to the reflecting plate and the casting sand. When image processing is performed by projecting light and receiving light reflected from these reflectors and casting sand, the reflected light from the reflector (background) having a smooth surface becomes strong specular light, and the sand has an uneven surface shape. Therefore, the reflected light from the casting sand becomes weak diffusely reflected light, so that the obtained image is an image having a clear black and white contour independent of the color of the sand. As described above, there is an effect that an accurate contour between the sand and the background can be obtained without being affected by the difference in the transparency and the color of the foundry sand at all.

According to the invention described in claim 2 of the present invention,
In addition to the effect of the first aspect of the present invention, the above-mentioned reflecting plate is set to a glass plate, so that the glass plate has high reflectivity and a smooth surface, so that the brightness of the foundry sand and the background (glass plate) The difference (contrast) from the luminance of the image is further increased, and as a result, there is an effect that a more accurate contour can be secured. In addition, since the glass plate does not have a flaw like a plastic plate, the surface condition such as a flaw, which is disadvantageous for measurement, is not input as an image, and the management becomes easy.

According to the third aspect of the present invention,
In addition to the effect of the second aspect of the present invention, the glass plate is set to have a thickness greater than the depth of focus of the camera. An object is prevented from being imaged, so that there is an effect that the object located below the glass plate is not adversely affected at all.

According to the invention described in claim 4 of the present invention,
In addition to the effect of the second aspect of the present invention, a metal reflection plate is provided below the glass plate, so that a higher reflection amount of reflected light can be obtained and the contrast can be further improved. is there.

According to the invention described in claim 5 of the present invention,
In addition to the effect of the first aspect of the present invention, since the above-described image processing detects the contour of the foundry sand, there is an effect that the contour of the sand and the background can be reliably detected.

According to the sixth aspect of the present invention, in addition to the effect of the fifth aspect of the present invention, the threshold value for binarization is set based on the relationship between the molding sand and the background. There is an effect that it is hardly affected by disturbance light and can execute accurate measurement.

According to the invention described in claim 7 of the present invention,
In addition to the effect of the first aspect of the present invention, the light source (for example, a halogen lamp) has a luminous intensity adjusting function, so that it can sufficiently cope with deterioration of the light source due to aging or aging of the light source. Thus, there is an effect that highly accurate measurement can be performed.

According to the eighth aspect of the present invention,
The above-mentioned light source emits light parallel to the optical axis of the image processing camera onto the glass plate and the molding sand, and the image processing camera arranged at right angles to the glass plate has weak irregular reflection from the molding sand having an uneven surface. Light and strong specularly reflected light from a glass plate provided with a metal reflection plate below are received and imaged.

As a result, an accurate contour can be obtained irrespective of the difference in transparency and color of the molding sand, and the difference (contrast) between the luminance of the sand and the luminance of the background is extremely large, so that a clear contour is secured. There is an effect that can be. That is,
The sharp contour as described above can be ensured by the point that the glass plate has a high reflectivity and a smooth surface, and the point that a higher reflection amount of reflected light can be obtained by disposing the metal reflector.

According to the ninth aspect of the present invention,
In addition to the effect of the eighth aspect of the present invention, since the above-described image processing detects the contour of the foundry sand, the contour of the sand and the background can be reliably detected.

[0037]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below in detail with reference to the drawings. The drawings show an image measuring method and an apparatus for an image of a molding sand. First, the configuration of an image processing and measuring apparatus for a molding sand will be described.

1 and 2, the image processing and measuring apparatus is provided with an XY stage 1 which can be moved and adjusted in a horizontal X-axis direction and a horizontal Y-axis direction of a virtual coordinate axis, and a measuring plate 2 is mounted on the XY stage 1. Are positioned and detachably mounted. A background plate 5 having an upper and lower two-layer structure in which a metal reflection plate 4 is disposed below a glass plate 3 is arranged inside the measurement dish 2 described above.

Here, as the above-mentioned glass plate 3, a transparent, light-transmissive, smooth surface, high reflectivity and uniform colorless and transparent surface is used, and the thickness L (see FIG. 3) of the glass plate 3 will be described later.
The depth is set to be deeper than the focal depth of the camera 6. Further, as the above-mentioned metal reflection plate 4, a highly reflective and glossy metal plate, for example, an aluminum plate, an iron plate, a stainless plate, or the like is used.

On the other hand, a C as an image processing camera is provided above the XY stage 1 so as to be perpendicular to the glass plate 3 described above.
A CD camera 6 is mounted, and a microlens 7 with coaxial falling illumination as an optical system is provided below the CCD camera 6. A light source 9 composed of a halogen lamp or the like is provided above the power supply 8, and this light source 9 is connected to a predetermined portion of the microlens 7 by an optical fiber 10, and the light source 9 10, a structure in which light parallel to the optical axis of the CCD camera 6 is projected onto the glass plate 3 and the plurality of molding sands A provided on the glass plate 3 via the microlens 7. ing.

A power supply line and a signal line 11 are connected between the CCD camera 6 for receiving and imaging the reflected light from the molding sand A and the glass plate 3 through the microlens 7 and the power supply 8 described above. Have been. Further, a keyboard (input operation means) 12 and a control unit (control means)
13 and an image processing device 15 including a display unit (monitor means) 14. The power supply 8 and the control unit 13 are connected by a video outline 16 to display an image captured by the CCD camera 6. It is configured to perform image processing.

On the other hand, an adjusting unit 17 is connected to the light source 9 described above, and the adjusting unit 17 is configured to adjust the amount of light from the light source 9. The control unit 13 described above, as shown in FIG.
It includes a ROM 18 for storing programs, a RAM 19 for storing various data, and a CPU 20. The CPU 20 controls the driving of the CCD camera 6 and the light source 9 via the power supply 8 based on an input signal from the keyboard 12, and The display unit 14 is controlled based on an image signal input from the camera 6 via the video outline 16.

As shown in FIG. 3, the above-mentioned micro lens 7 is arranged at a half mirror 21 for converting light emitted from the light source 9 into light parallel to the optical axis of the CCD camera 6, and at a lower portion and an upper portion of the half mirror 21. The optical system includes convex lenses 22 and 23, and these elements 21 to 23 are integrated into an integrated unit.

As shown in FIG. 4, the light a projected from the light source 9 via the microlens 7 is reflected by the casting sand A and the glass plate 3 to be reflected light, but is reflected by glass having a smooth surface. The reflected light from the plate 3 becomes strong regular reflected light b, and the light from the foundry sand A becomes weak diffusely reflected light c due to the uneven surface shape of the foundry sand A.

The CPU 20 takes in the image (see FIG. 6) taken by the CCD camera 6 and then binarizes it with a threshold to form a binarized image (see FIG. 7). Binarization and contour extraction means (refer to the tenth step S10 in the flowchart shown in FIG. 5) for extracting a contour from the binarized image (see FIG. 8), and a feature quantity for measuring a feature quantity such as an aspect ratio and a roundness The measurement means (refer to the eleventh step S11 in the flowchart shown in FIG. 5) compares the measured average value of the plurality of aspect ratios with a predetermined value (predetermined value of the aspect ratio) to determine whether the polishing evaluation is OK or NG. Polishing evaluation means for executing (Step 18 in the flowchart shown in FIG. 5)
18). On the other hand, a video capture card is inserted and connected to the control unit 13 as needed.

The method for performing the image processing and measurement of the molding sand by using the apparatus for image processing and measuring of the molding sand thus configured will be described in detail below with reference to the flowchart shown in FIG. The first step S1 to the fifth step S5 are routines for executing illuminance management.

First, in a first step S1, a measuring dish 2 on which a background plate 5 is arranged is prepared. At this time, the sand on the glass plate 3 is removed for the purpose of illuminance management without putting sand on the upper portion of the glass plate 3. Next, in the second step 2,
The CPU 20 displays a through image of the background captured by the CCD camera 6 on the display unit 14, and in the next third step S3, C
The PU 20 captures a background still image.

Next, in a fourth step S4, the CPU 20 calculates the average luminance K of the background.
The PU 20 determines whether or not the average luminance K is within a predetermined range of 210 to 252. When the determination is NO, the process returns to the second step S2, while when the determination is YES, the next sixth step S6 is performed.
Move to

Here, the above-mentioned average luminance K of the background is given by K = 2.
The range of 10 to 252 is set for the following reason. FIG. 9 is a characteristic diagram showing the change between the average luminance d of sand and the average luminance K of the background by taking the illuminance of the light source on the horizontal axis and the luminance of the image on the vertical axis. And the average luminance d increase in proportion to this, but the average luminance K of the background is saturated from a certain point due to the limit of the CCD camera 6 and the image processing device 15 side. At the point of 5000 lux, the difference between the average luminance of the sand and the background becomes maximum, and the luminance of the image at this point is 252.
Becomes If the illuminance with the luminance 9 exceeds 5000 lux, even the sand which is originally black is whitened.

If the luminance of the image is less than 210, the difference in the average luminance between the sand and the background becomes too small. K for these reasons
= 210 to 252, and the operation of the adjusting unit 17 manages the light amount of the light source 9, particularly the illuminance of the light source 9 corresponding to the horizontal axis in FIG. 9, so that the optimal illumination condition for measurement can be secured. Make.

Next, in a sixth step S6, input processing of a target quantity (for example, 30 pieces) of the molding sand A to be measured and a sand size are executed. This process is manually input by the measurer using the keyboard 12. Next, in a seventh step S7, the measuring dish 2
A plurality of molding sands A are placed on the glass plate 3 in the above. At this time, the sand is separated from each other.

Eighth Step S8 to Sixteenth Step S16
Is a routine for executing image processing measurement. In the eighth step S8, the CPU 20 displays the molding sand A and the through image of the background captured by the CCD camera 6 on the display unit 14 under the illumination condition (see FIG. 6). In this case, as already described with reference to FIG. 4, the reflected light from the glass plate 3 having a smooth surface becomes strong specular reflected light b, and is further reflected by the metal reflecting plate 4 disposed on the lower surface thereof. Since a higher light reflection amount is obtained and the reflected light from the casting sand A becomes weak diffusely reflected light c, the display image has a white background portion and a black sand A portion as shown in FIG. Become.

Next, in a ninth step S9, the CPU 20 captures a still image. Next, in a tenth step S10, a binarization process is executed and a contour is extracted. That is,
As shown in FIG. 9, the binarization threshold is fixed to a predetermined value (for example, image luminance = 100) in relation to the change in the average luminance d of the foundry sand A and the change in the average luminance K of the background. The binarization threshold is fixed so as to be an intermediate value between the upper limit value of the variation of the average luminance d of the foundry sand A and the lower limit value of the variation of the average luminance K of the background. = White and luminance 101 to 255 as "0" signal = black and the binarization process is executed, the captured image shown in FIG.
And a highly accurate binarized image which is not affected by disturbance light.

The CPU 20 detects and extracts the contour e between the foundry sand A and the background from the binarized image of FIG. 7 and forms it as shown in FIG. In step S11, the CPU 20 determines in FIG.
The characteristic amount of the foundry sand A is measured from the contour extraction image of the above.

Specifically, the aspect ratio and the roundness are determined. At the time of measuring the aspect ratio, as shown in FIG. 8, the center of gravity is first obtained, then the main axis of inertia 24 is drawn, and two lines 25, 25 parallel to the main axis of inertia 24 and two lines 26, 26 perpendicular to the main axis of inertia. 26, and the length of the short side between the lines 25 and 25 (horizontal) is determined by the length of the long side between the lines 26 and 26 (vertical).
Divide by and measure the aspect ratio. When the aspect ratio is obtained in this way, this value can be measured quickly.
On the other hand, the roundness can be obtained by the following equation (Equation 1).

[Equation 1] Roundness = square of perimeter / (4π × area) In the next twelfth step S12, the CPU 20 traces and displays the contour of the foundry sand A on the captured image (see FIG. 6).
In this trace display, for example, a red line, which is different from the color of the background image and the sand image (that is, white and black), is traced and displayed along the contour. This trace display is executed for the purpose of preventing dusts and castings other than sand from being mistakenly recognized as sand, or a plurality of sands being mistakenly recognized as one sand.

Next, in a thirteenth step S13, the measurer visually recognizes the trace display, and inputs YES or NO using the keyboard 12 as to whether or not the outline is erroneously recognized. Next, in a fourteenth step S14, the CPU 20 determines whether the answer
It is determined whether there is no misidentification based on the keyboard 12 input of O. When the judgment is NO (at the time of misidentification), the process returns to the eighth step S8. Move to step S15.

In the fifteenth step S15, the CPU 20
Stores the measurement data of the feature amount in a predetermined area of the RAM 19 or the like. Next, in a sixteenth step S16, the CPU 20 determines whether or not the number of measurements has reached the target total number (for example, 30). If the determination is NO, the CPU 20 returns to the eighth step S8 to repeat the same measurement as described above, while YES At the time of judgment, the first
Control goes to step S17.

Seventeenth step S17 to twentieth step S
Reference numeral 20 denotes a routine for executing data processing. In a seventeenth step S17, the CPU 20 executes statistical processing of the measurement data. Specifically, an average value of the aspect ratio for the target total number is obtained. Next, in an eighteenth step S18, the CPU 20 compares the predetermined value stored in a predetermined area of the RAM 19 in advance with the average aspect ratio to execute polishing evaluation (OK or NG determination).

At the time of OK, the next 19th step S
19, while another twentieth step S
Move to 20. In the ninth step S19, the CPU
20 displays OK on the display unit 14 in response to the OK determination. In addition, in the above-described twentieth step S20, the CPU 20 performs NG display on the display unit 14 in response to the NG determination, and ends a series of measurement processing.

In short, according to the image processing and measuring method of the molding sand of the above embodiment, the molding sand A is disposed on the above-mentioned reflecting plate (see the glass plate 3) and the camera light from the light source 9 such as a halogen lamp is provided. Light a parallel to the axis is reflected by a reflecting plate (see glass plate 3),
When the light is projected onto the casting sand A and the image processing is performed by receiving the reflected light b and c from the reflecting plate (see the glass plate 3) and the casting sand A, the light from the reflecting plate having a smooth surface (see the glass plate 3) is obtained. The reflected light becomes strong specular reflected light b, and the reflected light from the casting sand A becomes weak diffusely reflected light c due to the uneven surface shape of the sand A. Therefore, the resulting image (see FIG. 6) is sandy. An image having a clear black and white outline that does not depend on the color of A is obtained. As described above, there is an effect that an accurate contour between the sand A and the background can be obtained without being affected by any difference in the transparency and the color of the foundry sand A.

Further, since the above-mentioned reflecting plate is set to the glass plate 3, since the glass plate 3 has high reflectivity and a smooth surface, the brightness of the molding sand A and the brightness of the background (glass plate 3) are different. The difference (contrast) is further increased, and as a result, there is an effect that a more accurate contour can be secured. In addition, since the glass plate 3 does not have a flaw like a plastic plate, the surface condition such as a flaw that is disadvantageous for measurement is not input as an image, and the management is easy.

Further, since the above-mentioned glass plate 3 is set to have a thickness L larger than the depth of focus of the camera 6, the image processing camera (see the CCD camera 6) uses the metal reflection plate 4 and the XY An object such as the stage 1 is prevented from being imaged, so that there is an effect that the object located below the glass plate 3 is not adversely affected at all.

Further, since the metal reflection plate 4 is provided below the glass plate 3, a higher reflection amount of the reflected light b can be obtained and the contrast is further improved.

In addition, since the above-described image processing detects the contour e of the foundry sand A, there is an effect that the contour between the sand A and the background can be reliably detected. Further, since the threshold value for binarization is set based on the relationship between the casting sand A and the background, there is an effect that it is hardly affected by disturbance light and accurate measurement can be performed.

Further, since the above-mentioned light source 9 (for example, a halogen lamp) has a luminous intensity adjusting function, it can sufficiently cope with deterioration of the light source 9 due to aging or deterioration of the light source 9 with high accuracy. There is an effect that measurement can be performed.

On the other hand, according to the molding sand image processing and measuring apparatus of the above embodiment, the light source 9 is an image processing camera (CCD).
The light a parallel to the optical axis of the camera 6 is projected on the glass plate 3 and the casting sand A, and the surface of the image processing camera (see the CCD camera 6) arranged at right angles to the glass plate 3 is uneven. Weakly diffused light c from the foundry sand A and metal reflector 4
Receives and images strong intense reflected light b from the glass plate 3 on which is disposed. As a result, an accurate contour can be obtained irrespective of the difference in the transparency and color of the foundry sand A, and the difference (contrast) between the luminance of the sand A and the luminance of the background is extremely large, and a clear contour is secured. There is an effect that can be.

That is, due to the point that the glass plate 3 has high reflectivity and a smooth surface and the arrangement of the metal reflection plate 4, the reflected light b
With the point that a higher reflection amount can be obtained, a clear contour as described above can be secured. Further, since the above-described image processing detects the contour e of the foundry sand A, there is an effect that the contour between the sand A and the background can be reliably detected.

In the correspondence between the configuration of the present invention and the above-described embodiment, the reflecting plate of the present invention corresponds to the glass plate 3 of the embodiment, and similarly, the image processing camera corresponds to the CCD camera 6. However, the present invention is not limited only to the configuration of the above embodiment.

For example, in place of the processing in the twelfth and thirteenth steps S12 and S13 shown in FIG. 5, sand A having an aspect ratio of 0.5 or less or a roundness of 0.4 or less is replaced with dust. The CPU may automatically determine that the object is a casting or a plurality of sands, and the binarization threshold may use a value of luminance = 90 instead of luminance = 100 in FIG.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an image processing and measuring apparatus for molding sand of the present invention.

FIG. 2 is a control circuit block diagram of the device.

FIG. 3 is an explanatory diagram showing a relational structure between a microlens and reflected light.

FIG. 4 is an explanatory diagram showing a relationship between incident light and reflected light.

FIG. 5 is a flowchart showing an image processing measurement method for foundry sand of the present invention.

FIG. 6 is an explanatory diagram of an image captured by a CCD camera.

FIG. 7 is an explanatory diagram of a binarized image.

FIG. 8 is an explanatory diagram of a contour extraction image.

FIG. 9 is a characteristic diagram showing changes in average luminance of sand and a background.

FIG. 10 is an explanatory view showing a conventional image processing and measuring method for foundry sand and its apparatus.

FIG. 11 is an explanatory diagram of a grayscale image by a conventional means.

[Explanation of symbols]

 3: Glass plate (reflection plate) 4: Metal reflection plate 6: CCD camera (image processing camera) 9: Light source A: Foundry sand e: Outline

Claims (9)

[Claims] An image processing and measuring method for molding sand by binarization processing, wherein the molding sand is disposed on a reflecting plate having a light transmitting property and a smooth surface, and the image processing camera is perpendicular to the reflecting plate. And an image processing and measuring apparatus for projecting light parallel to the optical axis of the image processing camera from the light source to the reflection plate and the molding sand, and receiving the light reflected from the molding sand and the reflection plate to perform image processing. Law. 2. The apparatus according to claim 1, wherein said reflector is a glass plate.
Image processing measurement method of the foundry sand described. 3. An image processing and measuring method for molding sand according to claim 2, wherein said glass plate is set to a thickness deeper than a depth of focus of a camera. 4. The method according to claim 2, wherein a metal reflecting plate is provided below the glass plate. 5. The method according to claim 1, wherein the image processing detects a contour of the foundry sand. 6. A method according to claim 5, wherein a threshold value for binarization is set in relation to the background of the foundry sand. 7. The light source according to claim 1, wherein said light source has a light intensity adjusting function.
Image processing measurement method of the foundry sand described. 8. An image processing and measuring apparatus for molding sand by binarization processing, comprising: a glass plate having a light transmitting property and a smooth surface, on which a molding sand is disposed, and An image processing camera disposed at a right angle, and a light source for projecting light parallel to the optical axis of the image processing camera to a glass plate and casting sand, and a metal reflection plate is disposed below the glass plate. Image processing and measuring equipment for foundry sand. 9. The image processing and measuring apparatus for molding sand according to claim 8, wherein said image processing detects a contour of the molding sand.