JP3404715B2 - Internal inspection method for wide section hollow path - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for inspecting the inside of a wide-section hollow path for checking the presence or absence of an internal blockage of a wide-section hollow path such as a cooling water passage of an engine head cylinder. Things. 2. Description of the Related Art A water-cooled engine has a cooling water passage (water jacket) for a combustion chamber in a cylinder block and a head cylinder, and circulates cooling water in this portion to prevent seizure of the engine. 4 (a) and 4 (b) show a bottom view and a partial vertical sectional view of an example of the head cylinder (1). As shown in FIG. 4A, the head cylinder (1) has water holes (3) formed on the lower surface side of the head (cylinder block) along the periphery of the cylinder cylinder (2). The water holes (3) form a circulating cooling water passage when the head cylinder (1) is connected to the cylinder block, and a cooling water passage hollow passage (4) between adjacent water holes that cannot be observed from outside. To form A sand hole is formed around the ignition plug and the intake / exhaust valve on the upper surface of the head, and a cooling water passage is formed between the sand holes. When forming the cooling water channel water hole (3) and the hollow channel (4), a core is set in a mold, molten metal (for example, molten aluminum metal) is poured and solidified.
Although the mold and the core are removed to obtain a product, the cooling channel of the head cylinder (1) is more complicated in shape than the cooling channel of the cylinder block, and core sand is likely to remain without being removed. In particular, since the inside of the hollow passage (4) cannot be observed from the outside, the core sand often moves to the final step with the core sand remaining. As a result, in the worst case, the engine must be disposed of as a defective product. There may not be. Further, when the core is formed or set in a mold, if the core is partially missing or has a crack, if the core is set in the mold as it is, the molten metal poured into the mold will lose these defects. As a result of flowing into the location and the melting location and remaining as casting burrs, the cooling water passage is blocked, and the cooling effect of the engine is deteriorated. Therefore, it is necessary to inspect the inside of the bent hollow path (4) in particular to check for abnormalities such as abnormal shapes and remaining cores. One example of the inspection means is shown in FIG.
Next, with reference to FIG. The inspection means (5) inserts a light projecting part (6) made of a linear light guide such as an optical fiber into a water hole (opening of a hollow path) (3) of a head cylinder (1), and inserts the light into the path. The diffused light (La) is projected. Then, the light emitted from the other opening of the hollow path (4) is received by the camera (7) and is imaged in a two-dimensional plane, the area of the plane image is measured, and the inspection unit determines whether or not there is an internal blockage by fuzzy inference. Is to be inspected. [0006] The above-mentioned hollow path (4)
In the means for inspecting the presence or absence of an internal blockage, since the area data of the planar image is determined by fuzzy inference, when the cross-sectional area of the hollow passage (4) such as the cooling water passage or the intake / exhaust passage becomes large, the water passage is slightly increased. Even if is occluded, a sufficient amount of light is emitted, and erroneous determination of occlusion (abnormal) as no occlusion (normal)
Also, because the inner surface is rough due to the degree of baking, the amount of emitted light is greatly attenuated, and there is a possibility of erroneously determining that no occlusion is present with occlusion, etc.
There is a problem that the presence or absence of blockage cannot be accurately inspected by simple area measurement. SUMMARY OF THE INVENTION An object of the present invention is to provide a method for inspecting the inside of a wide cross-section hollow path which can correctly inspect the presence or absence of blockage in the inside of the path even if the cross-sectional area of the hollow path such as the cooling water passage or the suction / exhaust passage of the head cylinder becomes large. That is. According to the present invention, when inspecting the inside of a hollow passage having a bent wide cross section for the presence or absence of an obstruction, the present invention projects diffuse light from the passage opening and diffuses and reflects the light inside the passage. Receiving the captured light in a two-dimensional plane at another path opening by a predetermined image capturing means and capturing an image, and binarizing the captured image by a predetermined threshold value and extracting the area from the binarized image .
Values, perimeters, circumscribed rectangular areas, and features of the center of gravity are measured, and the relevance of each measured data to the normal data is determined by fuzzy inference , and the reciprocal power of the relevance is determined.
A step of examining internal blockage presence of hollow path calculated values compared discriminant a reference value, the measurement area by occlusion whether small obstruction
Binarization if the center of gravity is the same position even if it is determined to be present
Re-binarize the captured image by lowering the threshold and re-binary image
Is extracted, the brightness area of the image is re-measured, and the
If the product is larger than the previous inspection, there is no occlusion and the remeasurement area is small.
A step of determining that there is a blockage when the pressure is constant . DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the method for inspecting the inside of a hollow passage having a wide cross section according to the present invention will be described below with reference to FIGS. First, FIG. 1A shows a sectional view of a head cylinder (9) having a hollow passage (8) having a wide cross section such as a cooling water passage and an intake / exhaust passage, and a water hole (10) and a sand hole are provided in the hollow passage (8). (11) is formed, and the light projecting unit (12) and the imaging unit (13) are inserted and installed in both holes (10) and (11), respectively. The light projecting section (12) is composed of an optical fiber connected to a diffused light source, and projects diffused light from a water hole (10). The imaging unit (13) is composed of a camera, receives light incident from the water hole (10), irregularly reflects in the hollow path (8), and receives light emitted from another opening (sand hole) (11) in a two-dimensional plane. Image. (M) is a blocking substance such as a core, and (Lb) is diffused light. The operation (method) of the present invention based on the above configuration will be described below. First, when inspecting the presence or absence of blockage inside the hollow passage of the head cylinder (9) as an object to be inspected, FIG.
As shown in (a), the optical fiber (1) is inserted into the water hole (10).
Insert the light emitting end of 2). When the diffused light (Lb) is projected into the hollow path (8) therefrom, even if the path (8) is bent, the diffused light (Lb) diffuses and reflects through the path (8) and passes again. It injects from another opening, a sand hole (11). Then, the light (L
b) is accurately received by the camera (13) and two-dimensionally imaged. Then, for example, when there is no core (m), since a sufficient amount of emitted light (Lb) is received, as shown in FIG. 1B, the brightness area (Po) of the captured image is obtained.
Becomes larger. On the other hand, when the core (m) remains in the hollow path (8), since the reflectance of the core (m) is small,
As shown in FIG. 1C, the area (Po ′) and the perimeter of the emitted light (Lb) are reduced. Therefore, a feature amount such as a brightness area value for each route exit is measured from the captured image, and the presence or absence of the blockage in the hollow route (8) is inspected by fuzzy inference. In the fuzzy inference, FIG.
As shown in the luminance distribution (Ba), the binarization thresholds (Ha) are set in accordance with the object to be inspected prior to discrimination, and from the image captured by the camera (13), the binarization threshold (Ha) is set to 2 or more. The binarized image (Da) {see FIG. 2C} is taken out and inspected based on the image area and other characteristic amounts. still,
In the case of a non-defective product in which the inside of the hollow path (8) is not closed, if the binarization threshold (Ha) is reduced, the area (Po) of the binarized image (Da) increases. On the other hand, in the case of a defective product closed by the core (m) or the like, the amount of emitted light decreases, and FIG.
As shown in the luminance distribution (Bb) of FIG.
The binary image area (Po ') is constant or reduced even if a) is lowered, or becomes 0 as shown in FIG. or,
The luminance distribution indicated by the dotted line in FIG. 2A is a case where the inner surface of the hollow path is rough or satin-like, so that the surface roughness is poor and the amount of emitted light is reduced even if it is a good product. Further, as shown in FIG. 3, the distribution of characteristic quantities such as the area of an image serving as a reference of an object to be inspected is measured in advance, and a membership function (Ma) for fuzzy inference is created for each route exit. deep. The membership function (Ma) measures the area and perimeter of a plurality of non-defective or defective products,
A probability distribution is drawn with (Na) as a normal region and (Nb) and (Nc) as abnormal regions. The probability distribution is created for each path and for each feature amount such as area. Then, for example, the measured area data is converted into a membership function (Ma)
And the degree of conformity (Q) of the measured data to the normal data is derived from the membership function (Ma). For example, when the measured area in the area distribution is (Pa), the degree of conformity (Q) to the normal data is (Qa). At this time, the hollow path (8) is determined from the fitness (Q).
As described above, when inspecting the presence or absence of occlusion, if the hollow path (8) has a wide cross section, accurate determination cannot be performed only with the area data, and there is a risk of erroneous determination. Therefore, as shown in FIG. 1B, in addition to the area value, as shown in FIG. 1B, a perimeter (Uo), a circumscribed rectangular area (Vo), and a center of gravity (Go) are used. At least two or more of the included feature values are measured. Then, for the other feature values (Uo) (Vo) (Go) as well as the area value (Po), the fitness (Q)... Is derived, and at least two or more fitness (Qb) (Qc). In combination, the presence or absence of occlusion in the hollow passage (8) is inspected. Note that the circumscribed rectangle is a rectangle in which each side circumscribes a bright color region extracted by the binarized image, and the axis directions of two orthogonal sides of the rectangle are the major axis of the equivalent ellipse of the bright color region. It refers to a rectangle equal to the minor axis. [0015] Therefore, compared judged suitable Godo (Qb) multiplication value (Qc) (Qb × Qc = Qd) a reference value (Qr),
When Qd> Qr, it is determined that the product is good, and the presence or absence of blockage in the hollow path (8) is inspected. If more features are measured in the same manner, the inspection accuracy is further improved. Next, as shown in FIG. 1 (d), when the inner surface is rough and the surface roughness is poor, the measured area (Pt) is small, and if no occlusion is erroneously determined to be occlusion, the center of gravity ( Gt)
Is the same position, the binarization threshold (Ha) is reduced, the captured image is binarized again, a binarized image is extracted, and the brightness area of the image is measured again. If the remeasured area is larger than the previous inspection, it is determined that there is no blockage, and if the remeasured area is smaller or constant, it is determined that there is a blockage. Further, in the case of the sand mist shown in FIG. 1 (e), the sum of the perimeters (Ui).
If all the circumscribed rectangular areas (Vi) are substantially equal to no occlusion, the binarization thresholds (Ha) are reduced and the measurement is performed again. If the area (Vi)... Becomes large, it is determined that there is no blockage, and if not, it is determined that there is blockage. According to actual measurements, 50 mm in the cooling water channel of φ40
% Occlusion could be tested with a 99% determination rate. According to the present invention, in inspecting the presence or absence of an internal blockage of a hollow passage having a wide cross section, such as a cooling water passage, in a head cylinder of an automobile engine, diffused light is emitted from the passage opening, and The light that has diffusely reflected through the inside is received by a predetermined image pickup means at another path opening on a two-dimensional plane and captured, and the captured image is binarized at a predetermined threshold value to extract a binarized image. Two or more types of features are measured, the degree of conformity of each measured data to the normal data is determined by fuzzy inference, and each degree of conformity is combined to inspect for the presence or absence of an internal obstruction in the hollow path. The re-examination of the presence / absence of internal blockage by changing the threshold value makes it possible to accurately inspect the presence / absence of blockage inside the channel without being affected by variations in surface conditions and colors between lots even if the hollow path has a wide cross section. Inspection accuracy Significantly improved.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 (a) is a cross-sectional view of a hollow path showing an embodiment of a method for inspecting the inside of a wide-section hollow path according to the present invention. (B)
(C), (d), and (e) are the respective binarized image diagrams according to the present invention in the case of no blockage, in the case of blockage, in the case of poor surface roughness, and in the case of sand dust. FIGS. 2A and 2B are luminance distribution diagrams of a picked-up image in each of the cases where there is no occlusion and where there is occlusion. (C) and (d) show FIG.
The figure which shows each binarized image of (b). FIG. 3 is a diagram illustrating an example of a membership function of fuzzy inference according to the present invention. FIG. 4A is a plan view showing an example of an automobile head cylinder. (B) is a longitudinal sectional view showing an example of a conventional hollow path internal inspection means. [Description of Signs] 8 Hollow path 10 Opening 11 Opening 12 Light projecting unit 13 Imaging means Lb Diffusion light m Blocking substance

Continuation of the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) G01N 21/84-21/958 G01B 11/00-11/30

Claims (1)

(57) [Claims 1] When inspecting the presence or absence of internal obstruction in a hollow path having a bent wide cross section, diffused light is projected from the path opening, and light that is diffusely reflected in the path and passed therethrough. Receiving light in a two-dimensional plane at another path opening by a predetermined imaging means and capturing the image, and binarizing the captured image with a predetermined threshold value and extracting the area value and surrounding area from the binarized image. Length, circumscribed rectangular area,
Two or more types of center-of-gravity features are measured, each fitness level of the measured data with respect to the normal data is determined by fuzzy inference, and a cross-multiplied value of each fitness level is compared with a reference value to determine and determine. A step of inspecting for the presence or absence of an internal occlusion of the path, and the center of gravity even if the measurement area is determined to be small due to the presence or absence of the occlusion.
If is the same position, lower the binarization threshold and
Re-binarize and extract the re-binarized image, and the brightness of the image
Re-measure area and make re-measurement area larger than previous inspection
No obstruction if occluded, obstruction if remeasurement area is small or constant
A method for inspecting the inside of a hollow passage having a wide cross section.