JP7785595B2 - Casting inspection equipment - Google Patents

Description

The present invention relates to a casting inspection device for inspecting castings such as disc rotors.

When adding some kind of identification information to a casting, cast letters may be formed during casting. For example, on a disc rotor formed by casting, the cast letters may include the manufacturer's name, a vehicle body specific symbol, and a wear limit mark. Note that in this specification, "characters" such as cast letters do not refer only to letters in the strict sense, such as the alphabet, but also include numbers, symbols, codes, marks, etc.

Casted letters may be missing or partially crushed, making them difficult to identify visually. Therefore, if the cast letters are difficult to identify and fall outside the acceptable range, they must be deemed defective, but sorting them visually is inefficient.

In response to this, a cast character recognition device has been proposed that uses a laser scanning sensor to measure cast characters in three dimensions, enabling automatic recognition of cast characters (see, for example, Patent Document 1).

Japanese Patent Application Laid-Open No. 2007-219943

When forming cast letters on a casting, they may be formed in a relatively inconspicuous location. Specifically, they may be formed on the inner circumferential surface of a through-hole. In the case of a ventilated disc rotor, the cast letters are formed on the inner circumferential surface of the ventilated portion.

In this case, conventional cast-in character recognition devices are configured to irradiate the cast character with a laser beam from above and detect the reflected light with a sensor directly above the cast character, making it impossible to recognize the cast character inside the through-hole. While it is possible to irradiate laser light from one side of the through-hole, the irradiated laser beam would only reach a portion of the cast character, leaving many areas where the reflected light does not return to the sensor, making it impossible to recognize the character accurately enough to determine whether the cast character is authentic. For this reason, the current situation is that inspection of cast-in characters formed on the inner surface of a through-hole is left to visual inspection by humans.

The present invention was made in consideration of the above circumstances, and aims to provide a casting inspection device that can efficiently and as accurately as possible inspect protrusions such as cast letters formed in through holes in castings.

In order to achieve the above object, the first invention provides:
A casting inspection device that inspects a protrusion that protrudes from an inner peripheral surface of a through hole formed in a casting,
a first light source that irradiates light of a first wavelength from a first end side of the through hole toward the protrusion;
a second light source that irradiates light with a second wavelength different from the first wavelength from a second end side of the through hole toward the protruding portion;
an imaging unit that captures an image of the protrusion from the first end side in a state in which the first light source and the second light source are emitting light;
an identification unit that extracts a first image based on the wavelength component of the first wavelength and a second image based on the wavelength component of the second wavelength from the imaging result obtained by the imaging unit, corrects the first image, and then generates a composite image by combining the corrected image and the second image, thereby identifying the shape of the protrusion;
Equipped with
The correction of the first image is characterized by increasing the brightness of a low brightness area that occurs in the area corresponding to the protrusion due to unevenness of the casting surface of the protrusion.

The second invention is
the imaging result is a color image,
In the color image, halation occurs in the same location as the portion of low brightness that occurs in the location corresponding to the protrusion in the first image,
The identification unit extracts a third image from the imaging result, which is a wavelength component of light having a wavelength different from the first wavelength and the second wavelength, which is the wavelength of light exhibited by the halation portion or an approximate wavelength thereof, converts the first image and the third image into grayscale images, compares the brightness of each pixel at the same coordinates between the first image and the third image, and uses the pixel with the higher brightness to generate the corrected image.

Note that in this second invention, "approximate wavelength" refers to a color having a wavelength within a range of 50 nm from the wavelength of the light emitted by the halation portion.

The third invention is
the first wavelength is a blue wavelength;
the second wavelength is a red wavelength;
The third image is an image based on wavelength components within a range from green to yellow.

The fourth invention is characterized in that the protrusions are cast letters.

According to the first invention, when light is irradiated from a first light source onto the protrusion from the first end side of the through hole, a shadow (first contour) is formed on the protrusion due to the light being blocked by the protrusion on the second end side of the through hole. Similarly, when light is irradiated from a second light source onto the protrusion from the second end side of the through hole, a shadow (second contour) is formed on the protrusion due to the light being blocked by the protrusion on the first end side of the through hole. By identifying the shape of the protrusion from these shadows (contours), it becomes possible to identify the shape of the protrusion even when light is irradiated onto the protrusion from the side rather than directly above.

Furthermore, when light is emitted from the first and second light sources simultaneously, the shadows that create the first and second contours are erased. In this regard, in the first invention, the first and second light sources emit light of different wavelengths, and after capturing an image using the imaging unit, a first image based on the first wavelength component and a second image based on the second wavelength component are extracted and these images are combined, allowing the shape of the protrusion to be identified using the shadows (contours). This eliminates the need for repeated imaging using light emitted from only one light source, then from only the other light source, allowing the shape of the protrusion to be identified in one go, improving inspection efficiency.

Furthermore, the unevenness of the casting surface of the protrusion causes diffused light, reducing the bounce of specularly reflected light irradiated from the first end, and therefore the imaging unit installed on the first end is unable to capture all of the specularly reflected light. As a result, in the first image, low-brightness areas appear in the areas corresponding to the protrusion, even though they should have been hit by light irradiated from the first end. If the first image is used as is to combine with the second image, these low-brightness areas remain, which can result in insufficient identification of the shape of the protrusion. In this regard, according to the first invention, correction is performed to increase the brightness of the low-brightness areas in the areas corresponding to the protrusion in the first image. This corrected image is used to generate an image combined with the second image, preventing low-brightness areas from remaining in the areas corresponding to the protrusion, thereby improving the accuracy of identifying the shape of the protrusion.

In the color image obtained as a result of the imaging, light of the first wavelength and light of the second wavelength are specularly reflected by the unevenness of the casting surface of the protrusion. In particular, specularly reflected light of the second wavelength light irradiated from the second end side opposite the imaging unit bounces back and enters the imaging unit, causing halation in places corresponding to the protrusion. Here, halation refers to a state in which the light intensity is particularly strong compared to other areas on the image. The halation areas occur in the same places as the low-brightness areas that occur in the places corresponding to the protrusions in the first image, and are caused by the unevenness that creates the low-brightness areas in the first image.

The unevenness that occurs on the casting surface varies from casting to casting, and because this variation is difficult to suppress, the location of halation (the same location as the low-brightness area that occurs in the area corresponding to the protrusion in the first image) varies depending on the casting or the location of the protrusion. In this regard, according to the second invention, halation is identified for each protrusion that is the subject of imaging. Then, by using the third image, in which halation areas that are brighter than other areas are displayed, and the first image, and combining the two images using the higher brightness for each pixel, the low-brightness areas in the first image are replaced with images of the halation areas, resulting in a composite image in which the brightness of those areas is increased. As a result, even if the location of halation varies, the low-brightness areas that occurred in the area corresponding to the protrusion in the first image can be accurately corrected to high-brightness areas.

According to the third invention, when blue wavelength light is irradiated from the first end and red wavelength light is irradiated from the second end, the wavelength of the light exhibited by the halation portion will be wavelength components in the range from green to yellow. Therefore, by using an image with wavelength components in this range as the third image to correct the first image, it is possible to prevent low-brightness areas from remaining in areas corresponding to protrusions.

According to the fourth invention, by inspecting cast letters that display information such as information used to identify a casting, it is possible to inspect whether the cast letters are human-readable.

2 is a schematic diagram showing a longitudinal section of a disk rotor and the configuration of an inspection device. FIG. 2 is a cross-sectional view of a disk rotor (cross-sectional view taken along line 2-2 in FIG. 1) and a schematic diagram showing a partial configuration of an inspection device. 5A and 5B are a flowchart showing processing by an image processing unit and an explanatory diagram showing images in the processing process. 5A and 5B are explanatory diagrams for comparing a color image and a first image, in which FIG. 5A shows the color image and FIG. 5B shows the first image.

One embodiment of the present invention will be described with reference to the drawings. A disc rotor 10 used as part of a vehicle's brake mechanism has multiple cast-in letters 11 formed on it. In this embodiment, the casting inspection device of the present invention is embodied as an inspection device 30 that inspects these cast-in letters 11.

<Configuration of disc rotor 10>
First, the configuration of the disc rotor 10 to be inspected by the inspection device 30 will be described. As shown in Figures 1 and 2, the disc rotor 10 is generally disk-shaped overall and has a hat portion 12 and a sliding portion 13. The hat portion 12 is attached to a hub provided at the end of an axle of a vehicle such as an automobile. The hat portion 12 has a bottom surface portion 14 and a peripheral surface portion 15.

The bottom surface portion 14 is circular and has a mounting hole 16 formed in the center. Multiple bolt insertion holes (not shown) are formed around the mounting hole 16. The mounting holes 16 and the bolt insertion holes are used to connect the disc rotor 10 to the hub. The peripheral surface portion 15 is cylindrical and extends from the outer periphery of the bottom surface portion 14, forming the peripheral surface of the hat portion 12.

The sliding portion 13 is connected to the end of the peripheral portion 15 opposite the bottom portion 14. The sliding portion 13 is the part that is sandwiched and pressed against the disc pad when the vehicle brakes. The sliding portion 13 is formed to protrude outward in an annular shape from the peripheral portion 15. The front and back surfaces of the sliding portion 13 form a pair of sliding surfaces 17 that are pressed against the disc pad.

The sliding portion 13 includes an inner disk portion 18, an outer disk portion 19 located more outer than the inner disk portion 18, and fins 20. The fins 20 connect the inner disk portion 18 and the outer disk portion 19 at multiple locations in the circumferential direction. The fins 20 extend radially, and the space surrounded by the inner disk portion 18, outer disk portion 19, and fins 20 forms ventilated portions 21 that penetrate in the radial direction (diameter). The ventilated portions 21 are flow paths through which air flows when the vehicle is running, and the flow of air allows the sliding portion 13 to be cooled quickly. The ventilated portions 21 correspond to through-holes.

The disc rotor 10 of this embodiment is an inner hat type in which the peripheral surface portion 15 and inner disc portion 18 are connected, and is a one-piece casting in which the hat portion 12 and sliding portion 13 are integrally formed.

The disc rotor 10 is formed with cast letters 11 as protrusions that protrude from the surface of the inner disc portion 18 facing the ventilated portion 21 toward the outer disc portion 19. One cast letter 11 is formed for each ventilated portion 21, and is formed by casting. The cast letters 11 are intended to display the manufacturer's name, vehicle-specific symbol, and wear limit mark. The cast letters 11 are formed closer to the outer peripheral edge than the inner peripheral edge of the ventilated portion 21, making it easier to visually confirm the displayed content from the outer peripheral side of the disc rotor 10.

A core is used during the casting process to form the ventilated portion 21 and the cast-in letters 11. A baseboard is used during the casting process to form a window portion 22 on the peripheral surface 15 of the inner-hat type disc rotor 10. The window portion 22 is a space that penetrates the peripheral surface 15 from the inside to the outside, and is formed at the same height as the ventilated portion 21. Furthermore, as shown in Figure 2, one window portion 22 is formed for each pair of adjacent ventilated portions 21 so that a core can be passed through them.

Here, because the cast letters 11 are formed integrally with the disc rotor 10 by casting, the letters may be missing or partially crushed. Therefore, it is necessary to inspect the cast letters 11 to ensure that the manufacturer's name and other information are still legible. The inspection device 30 used for this inspection is described below.

<Configuration of inspection device 30>
The inspection device 30 includes a support shaft 31 disposed on the inner periphery of the hat portion 12. The support shaft 31 extends in the vertical direction. An engagement portion 32 formed on the upper end of the support shaft 31 is inserted into the mounting hole 16 and engages with the disc rotor 10, thereby supporting the disc rotor 10 on the support shaft 31 in a state in which the disc rotor 10 can rotate integrally with the support shaft 31. A motor 33 is connected to the support shaft 31, and rotation of the motor 33 allows the disc rotor 10 to rotate about its own central axis.

A color camera 35, which serves as an imaging unit, and a blue LED 36, which serves as a first light source, are installed on the outer periphery of the hat portion 12. A red LED 37, which serves as a second light source, is installed in the gap between the inner periphery of the hat portion 12 and the outer periphery of the support shaft portion 31. The first end corresponds to the outer periphery of the hat portion 12, and the second end corresponds to the inner periphery of the hat portion 12.

The red LED 37 emits light with a wavelength corresponding to red through the window 22 from the inner circumferential edge to the outer circumferential edge of the ventilated portion 21, with the optical axis oriented horizontally along the ventilated portion 21. As shown in Figure 2, the red LED 37 emits light toward a pair of adjacent ventilated portions 21.

The blue LEDs 36 emit light with a wavelength corresponding to blue from the outer circumferential edge to the inner circumferential edge of the ventilated portion 21, with the optical axis directed horizontally along the ventilated portion 21. As shown in Figure 2, a pair of blue LEDs 36 are provided, each positioned on the extension of a pair of adjacent ventilated portions 21.

The color camera 35 is a camera that can simultaneously capture light of each wavelength emitted from the blue LED 36 and the red LED 37. The color camera 35 is positioned diagonally above the cast-in letters 11. Here, the depression angle θ1 of the color camera 35 is greater than the depression angle θ2 (=0 degrees) of the blue LED 36 and the red LED 37, whose optical axes are arranged horizontally. As shown in Figure 2, the color camera 35 is located between the pair of blue LEDs 36 in a plan view and on the extension of the optical axis of the red LED 37. The color camera 35 is set up so that it can simultaneously capture images of the cast-in letters 11 arranged on a pair of adjacent ventilated sections 21. For example, in the state shown in Figure 2, the two cast-in letters 11, "M" and "I," are captured simultaneously.

The inspection device 30 is equipped with a controller 40 that controls the motor 33, color camera 35, blue LED 36, and red LED 37.

The controller 40 has a rotation control unit 41, which controls the rotation of the motor 33. The controller 40 has an LED control unit 42, which controls the on/off of the pair of blue LEDs 36 and red LEDs 37. The controller 40 has a camera control unit 43, which controls the timing of image capture by the color camera 35.

The rotation control unit 41 rotates the disc rotor 10 and stops it at a rotational position where the red LED 37 is at the center of the window portion 22 and each blue LED 36 is at the center of each ventilated portion 21, as shown in Figure 2. With the rotation control unit 41 stopping the motor 33, the LED control unit 42 turns on each blue LED 36 and red LED 37, and at the same time, the camera control unit 43 causes the color camera 35 to capture an image. The color camera 35 simultaneously captures an image of the two cast letters 11 illuminated by each blue LED 36 and red LED 37.

When the color camera 35 has finished capturing an image, the LED control unit 42 turns off the blue LEDs 36 and red LEDs 37, and the rotation control unit 41 rotates the motor 33 until the red LED 37 is positioned at the center of the next window 22. This allows the next cast-in letter 11 to be captured.

The controller 40 is equipped with an image storage unit 44, which stores images captured by the color camera 35. The controller 40 is equipped with an image processing unit 45, which retrieves images captured by the color camera 35 from the image storage unit 44 and processes them to identify the shape of the cast letters 11. The processing executed by the image processing unit 45, which is an identification unit, is described below.

<Image processing flow>
In step S11, the image processing unit 45 determines whether or not a new image of the cast-in letters 11 has been captured by the color camera 35 based on the information stored in the image storage unit 44. If a new image of the cast-in letters 11 has not been captured, the process ends. If a new image has been captured, the process proceeds to step S12.

The color camera 35 captures images of two adjacent cast-in letters 11 at a time, and performs the following image processing on these two cast-in letters 11. For example, in the state shown in Figure 2, the two cast-in letters 11, "M" and "I," are captured and image processed simultaneously. However, since the image processing is the same for each cast-in letter 11, the following explanation will be given using the cast-in letter 11 shown as "M" in Figure 2 as an example.

In step S12, a filter that extracts only the blue wavelength component is applied to the image, and a grayscale first image 51 obtained using the blue wavelength component is extracted. Because the blue LED 36 is irradiated onto the cast-in letter 11 from the lower side (the outer periphery of the ventilated portion 21) in FIG. 3(a), in the first image 51, the area above a portion (upper portion) of the outline of the cast-in letter 11 is in shadow, as shown in FIG. 3(a). Therefore, the area above the upper portion of the outline of the cast-in letter 11 becomes a low-luminance area 52 that is less bright than the area below that portion, and the area below becomes a high-luminance area 55. The first image 51 is temporarily stored in the image storage unit 44.

Here, because the cast letters 11 are formed integrally with the disc rotor 10 by casting, their surfaces are cast-surfaces with irregularities. These irregularities cause the light emitted from the blue LED 36 to diffuse, reducing the bounce of the specularly reflected light. As a result, the color camera 35, which is mounted on the outer periphery of the hat portion 12, along with the blue LED 36, is unable to capture the specularly reflected light emitted from the blue LED 36. As a result, in the first image 51, low-brightness dark areas 53 appear in places corresponding to the cast letters 11, as shown in Figures 3(a) and 4(b), even though these areas should be hit by light emitted from the blue LED 36. Note that the dark areas 53 do not mean that the entire image is solid black. If the first image 51 in this state were used as is to perform image processing to identify the shape of the cast-in letters 11, the outline of the cast-in letters 11 would become unclear or part of the outline would be crushed due to the blackened areas 53 that appear on the letters, which could result in a decrease in the accuracy of measuring the line length of the outline and ultimately a decrease in the accuracy of character recognition.

Therefore, in step S13, a filter that extracts only the green wavelength component is applied to the image retrieved from the image storage unit 44, and a grayscale third image 54 obtained using the green wavelength component is extracted. The green wavelength component was selected for the following reasons.

As shown in Figure 4(a), in the color image 71 captured by the color camera 35, the area above the lower portion of the outline of the cast-in letter 11 is illuminated by light from the red LED 37 and appears red, while the area below that area is illuminated by light from the blue LED 36 and appears blue. Halation occurs in various places in the area corresponding to the cast-in letter 11, resulting in the appearance of halation areas 72. The halation occurs when light irradiated from the blue LED 36 and red LED 37 is specularly reflected by the unevenness of the cast surface of the cast-in letter 11, particularly the specularly reflected light of the red LED 37 irradiated from the inner periphery opposite the color camera 35, which bounces back and enters the color camera 35. Note that halation refers to a region in the color image 71 where the light intensity appears particularly strong compared to other regions. As shown in comparison with the first image 51 in Figure 4, the halation area 72 occurs in the same location as the black drop area 53 that occurred in the first image 51. This is because the halation area 72 is caused by the unevenness that causes the black drop area 53 in the first image 51.

The inventors performed a spectroscopic analysis of the halation portion 72 and examined its RGB components (red, green, blue). The results showed that the red and green elements were relatively stronger than the blue, and that the light from the halation portion 72 was yellow (with a wavelength of around 580 nm). Of the yellow RGB components, the red was excluded because it is used as light emitted from the red LED 37. The remaining green wavelength is an approximate wavelength of the yellow emitted by the halation portion 72. Therefore, in the image processing program executed by the image processing unit 45, the green wavelength was previously adopted as the wavelength component for identifying the halation portion 72. Note that approximate wavelength refers to a wavelength within a range of 50 nm either side of the wavelength of the light emitted by the halation portion 72.

The number of vertical and horizontal pixels in the third image 54 is the same as that in the first image 51. The image capture result is obtained when blue and red wavelength light is irradiated, so the third image 54, which is made up of green wavelength components, has low-brightness areas 52 overall, as shown in Figure 3(b). However, in areas corresponding to the dark areas 53 in the first image 51, the green wavelength components are relatively strong, resulting in high-brightness areas 55. The third image 54 is temporarily stored in the image storage unit 44.

Next, in step S14, the first image 51 and the third image 54, which have been temporarily stored in the image storage unit 44, are combined to generate a first combined image 56. In this case, the brightness of the pixels in the first image 51 and the third image 54 is compared for each pixel at the same coordinates, and the pixel with the higher brightness is used to generate the first combined image 56. Figures 3(a) and 3(b) show an example pixel 51p in the first image 51 and an example pixel 54p in the third image 54 to be compared. Note that the actual pixel size is smaller than shown.

The first composite image 56 is a corrected image obtained by correcting the first image 51. In the first composite image 56, as shown in FIG. 3(c), in the region above the upper part of the outline of the cast-in letter 11, pixels of either the first image 51 or the third image 54, whichever has the higher brightness, are used to form the low-brightness area 52, while in the region below the upper part of the outline, pixels of the first image 51 are used to form the high-brightness area 55. Furthermore, in the character portion of the cast-in letter 11, pixels of the third image 54 are used, and the brightness of the areas that were previously black areas 53 is increased.

In the following step S15, a filter that extracts only the red wavelength component is applied to the image retrieved from the image storage unit 44, and a second image 57 obtained from the red wavelength component is extracted. The number of vertical and horizontal pixels of the second image 57 is the same as that of the first image 51. As shown in FIG. 3(d), the red LED 37 illuminates the cast-in letters 11 from the upper side of FIG. 3(d) (the inner periphery of the ventilated portion 21). Therefore, in the second image 57, the area below a portion (the lower portion) of the outline of the cast-in letters 11 is in shadow, as shown in FIG. 3(d). Therefore, the area below the lower portion of the outline of the cast-in letters 11 becomes a low-luminance area 52 that is less bright than the area above that portion, and the area above becomes a high-luminance area 55. The second image 57 is temporarily stored in the image storage unit 44.

Then, in step S16, the first composite image 56 and the second image 57, which have been temporarily stored in the image storage unit 44, are composited to generate a second composite image 58. In this case, the brightness of the pixels in the first composite image 56 and the second image 57 is compared for each pixel at the same coordinates, and the pixel with the lower brightness is used to generate the second composite image 58. Figures 3(c) and 3(d) show an example pixel 56p of the first composite image 56 and an example pixel 57p of the second image 57 to be compared. Note that the actual pixel size is smaller than shown.

In the second composite image 58, as shown in FIG. 3(e), the area above the upper portion of the outline of the cast-in letter 11 uses pixels from the first composite image 56 to form the low-brightness area 52. On the other hand, the area below the outline of the cast-in letter 11 uses pixels from the second image 57 to form the low-brightness area 52. This makes the entire outline of the cast-in letter 11 appear embossed. In other words, the enclosed area 59 surrounded by the low-brightness area 52 of the first composite image 56 and the low-brightness area 52 of the second image 57 corresponds to the area corresponding to the cast-in letter 11. The second composite image 58 is temporarily stored in the image storage unit 44.

Then, in step S17, a cutout process is performed on the enclosed area 59 corresponding to the cast-in letter 11. The cutout process cuts out the boundary between the low-brightness area 52 and the enclosed area 59, and extracts a specific image 62 of only the character area 61 corresponding to the enclosed area 59, as shown in Figure 3(f). The specific image 62 is temporarily stored in the image storage unit 44.

As a result of the above processing by the image processing unit 45, a specific image 62 is generated that includes a character portion 61 corresponding to the cast-in character 11.

As shown in FIG. 1, the controller 40 is equipped with an image determination unit 46, which determines whether the character portion 61 included in the specific image 62 is within the normal range. The image determination unit 46 registers reference characters in advance and makes a determination by comparing the character portion 61 with the reference characters. For example, it can make a determination by comparing the overall area, partial area, dividing the characters and comparing the difference in length, or other comparisons. The determination method is not limited to this. If it is determined that any one of the character portions 61 read from the disc rotor 10 is not within the normal range, the disc rotor 10 is deemed a defective product and is excluded from shipment.

<Action and effect>
According to the inspection device 30 described above, the following effects can be obtained.

(1) The cast letters 11 formed on the ventilated portion 21 of the disc rotor 10 may be missing or partially crushed. Conventionally, whether the cast letters 11 are formed properly or not has been confirmed visually, but the inspection device 30 can automatically identify the cast letters 11 and determine whether they are defective.

(2) When the red LED 37 is irradiated onto the cast letter 11 from the inner periphery of the ventilated portion 21, the light is blocked by the cast letter 11, resulting in a shadow (outline) of the cast letter 11 on the outer periphery of the ventilated portion 21. Similarly, when the blue LED 36 is irradiated onto the cast letter 11 from the outer periphery of the ventilated portion 21, the light is blocked by the cast letter 11, resulting in a shadow (outline) of the cast letter 11 on the inner periphery of the ventilated portion 21. By identifying the shape of the cast letter 11 from these shadows (outlines), the shape of the cast letter 11 can be identified even when light is irradiated onto the cast letter 11 from the side rather than directly above.

(3) When light is emitted from the blue LED 36 and the red LED 37 simultaneously, the shadow (outline) of the cast-in letter 11 is erased. In this regard, the blue LED 36 and the red LED 37 emit light of different wavelengths, and after capturing an image with the color camera 35, a first image 51 with the red wavelength component and a second image 57 with the blue wavelength component are extracted and combined, allowing the shape of the cast-in letter 11 to be identified. This eliminates the need to repeatedly capture an image using light emitted only from the blue LED 36, and then capture an image using light emitted only from the red LED 37. This allows the shape of the cast-in letter 11 to be identified in one go, improving inspection efficiency.

(4) The unevenness of the casting surface of the cast letters 11 causes diffused light, reducing the bounce of specularly reflected light emitted from the blue LED 36, and the color camera 35 is unable to capture the specularly reflected light. As a result, in the first image 51, black areas 53 appear in the character portions of the cast letters 11, even though they should be illuminated by blue light emitted from the outer periphery. When the first image 51 is used as is and combined with the second image 57, the black areas 53 that appeared in the character portions of the cast letters 11 remain, which can result in insufficient identification of the shape of the cast letters 11. In this regard, the first image 51 is corrected to increase the brightness of the black areas 53. This corrected image is used to generate the combined image with the second image 57, preventing the black areas 53 from remaining in the character portions of the cast letters 11, thereby improving the accuracy of identifying the shape of the cast letters 11.

(5) Light of blue wavelengths and light of red wavelengths are specularly reflected by the unevenness of the casting surface of the cast letters 11, and in particular, specularly reflected light of red wavelengths irradiated from the inner periphery opposite the color camera 35 bounces back and enters the color camera 35. As a result, halation occurs in places corresponding to the cast letters 11 in the color image 71 captured by the color camera 35. The halation areas 72 occur in the same locations as the blackened areas 53 that occurred in the character portions of the cast letters 11 in the first image 51, and are caused by the unevenness that creates the blackened areas 53.

The unevenness of the casting surface varies from one casting to another, and because it is difficult to suppress this variation, the location of the halation portion 72 varies from one casting to another and from one location of the cast-in letters 11 to another. In this regard, the halation portion 72 is identified for each cast-in letters 11 to be imaged. Then, the third image 54, which displays the halation portion 72 with a higher brightness than the other areas, and the first image 51 and the third image 54 are combined by using the image with the higher brightness for each pixel. The dark portion 53 in the first image 51 is then replaced with the image of the halation portion 72, increasing the brightness of the dark portion 53. This allows the dark portion 53 that occurred in the character portion of the first image 51 to be accurately corrected to a higher brightness area, even if the location of the halation portion 72 varies.
<Modification>
A modification of the above embodiment will be described below.

(a) When the cast letter 11 is a character such as "O" or "X" that has multiple intersections with the light irradiation direction, it may not be possible to extract the entire outline of the cast letter 11 simply by shining light horizontally onto the cast letter 11 from each LED 36, 37. For example, in the case of "O," the outline on the outer periphery can be extracted, but the outline on the inner periphery may not be fully extracted. To deal with characters that have multiple intersections with the light irradiation direction, it is advisable to orient each LED 36, 37 diagonally downward from above the cast letter 11, within the range that does not interfere with the ventilated portion 21. Even in this case, it is necessary to set the depression angle θ1 of the color camera 35 larger than the depression angle θ2 (> 0 degrees) of the blue LED 36.

(b) As a correction method for increasing the brightness of the black drop portion 53 occurring in the first image 51, the third image 54 using the green wavelength component was extracted, and the first image 51 and the third image 54 were converted into grayscale images, the brightness of each pixel was compared, and the image with the higher brightness was used to generate the first composite image 56. Alternatively, the contours of the black drop portion 53 in the first image 51 may be identified by image recognition, and correction may be performed to increase the brightness of the identified black drop portion 53.

(c) In the image processing by the image processing unit 45, the green wavelength is selected as the wavelength component for extracting the third image 54. The wavelength component for extracting the third image 54 is not limited to this green wavelength, and the yellow wavelength exhibited by the halation portion 72 in the color image 71 may also be selected. Furthermore, orange, which is an approximate color with a longer wavelength than the yellow wavelength, may also be selected.

(d) In the inspection device 30, the LEDs 36, 37 are turned on while the disc rotor 10 is stopped from rotating, and after the color camera 35 captures an image, the LEDs 36, 37 are turned off before the disc rotor 10 is rotated. However, it is also possible to keep the disc rotor 10 rotating and the LEDs 36, 37 turned on, determine the image capture timing using a sensor, etc., and have the color camera 35 capture images of the cast characters 11 one after another. In this case, inspection efficiency can be further improved by stopping the rotation of the disc rotor 10 once it has made one revolution and replacing it with the disc rotor 10 to be inspected next.

(e) The disc rotor 10 does not have to have a one-piece structure. For example, the sliding portion 13 alone may be manufactured as a cast part, and the hat portion 12 may be manufactured from, for example, aluminum, and then connected to form a two-piece structure. Furthermore, instead of an inner hat type, the disc rotor may be an outer hat type in which the outer disc portion 19 and the peripheral surface portion 15 are connected. Furthermore, the shapes of the fins 20 and ventilated portion 21 are not limited to linear shapes, but may also be curved.

(f) The object to be inspected is not limited to the disc rotor 10, but may be any cast product with a through hole formed therein. In this case, the light source such as an LED and the imaging unit such as the color camera 35 may be inserted into the through hole from both ends to capture images.

(g) The inspection device 30 may be used to inspect not only the cast lettering 11, but also to check whether protrusions exceeding the tolerance range have been formed inside the through-hole.

(h) Although blue LEDs 36 and red LEDs 37 are used to emit light of different wavelengths from different directions, LEDs of other wavelengths may also be used. Furthermore, light sources other than LEDs may also be used. If a different combination of wavelengths is used for blue LEDs 36 and red LEDs 37, the wavelength components of the filter applied to extract third image 54 will also be different wavelength components. In other words, the halation portion 72 appearing in color image 71 is spectrally analyzed, and a wavelength of light exhibited by halation portion 72 or an approximate wavelength thereof, which is different from the first wavelength and the second wavelength, is selected.

10...Disc rotor (cast product), 11...Casted lettering (protrusion), 21...Ventilated portion (through hole), 30...Inspection device (cast product inspection device), 35...Color camera (imaging unit), 36...Blue LED (first light source), 37...Red LED (second light source), 45...Image processing unit (identification unit), 51...First image, 54...Third image, 56...First composite image (corrected image), 58...Second composite image (composite image), 72...Halation portion.

Claims (4)

A casting inspection device that inspects a protrusion that protrudes from an inner peripheral surface of a through hole formed in a casting,
a first light source that irradiates light of a first wavelength from a first end side of the through hole toward the protrusion;
a second light source that irradiates light with a second wavelength different from the first wavelength from a second end side of the through hole toward the protruding portion;
an imaging unit that captures an image of the protrusion from the first end side in a state in which the first light source and the second light source are emitting light;
an identification unit that extracts a first image based on the wavelength component of the first wavelength and a second image based on the wavelength component of the second wavelength from the imaging result obtained by the imaging unit, corrects the first image, and then generates a composite image by combining the corrected image and the second image, thereby identifying the shape of the protrusion;
Equipped with
A casting inspection device characterized in that the correction of the first image is performed by increasing the brightness of areas of low brightness that occur in the areas corresponding to the protrusions due to unevenness in the casting surface of the protrusions. the imaging result is a color image,
In the color image, halation occurs in the same location as the portion of low brightness that occurs in the location corresponding to the protrusion in the first image,
2. The casting inspection device according to claim 1, wherein the identification unit extracts a third image from the imaging result, the third image being based on a wavelength component having a wavelength different from the first wavelength and the second wavelength, the wavelength being the wavelength of light exhibited by a halation portion or an approximate wavelength thereof, converts the first image and the third image into grayscale images, and then compares brightness for each pixel at the same coordinates in the first image and the third image, and uses the pixel with the higher brightness to generate the corrected image. the first wavelength is a blue wavelength;
the second wavelength is a red wavelength;
3. The casting inspection device according to claim 2, wherein the third image is an image based on wavelength components in a range from green to yellow. A casting inspection device as described in claim 1 or 2, characterized in that the protrusion is a cast letter.