JP6996699B2 - Valve contact surface inspection method and inspection equipment - Google Patents

Description

The present invention relates to an inspection method and an inspection device for a valve contact surface of an engine.

The valves that control the intake and discharge of the engine into the combustion chamber need to be tightly sealed, and if there is a defect in the valve contact surface of the engine block, it is a serious defect that gas leaks. However, in addition to small scratches on the valve contact surface, small defects of 0.2 to 1.0 mm, which are generated when the rough material surface or the sintered body is processed, and recesses and holes may occur. Therefore, it is necessary to inspect the valve contact surface of the engine in the final process of processing.

Conventionally, the valve contact surface has been mainly inspected by the human eye. However, due to the problems of variation and eye fatigue caused by inspectors, automatic inspection technology is required. Therefore, as shown in Patent Document 1, an inspection method has been proposed in which the bulb contact surface is illuminated from the first and second light sources, and an image is taken from above the bulb contact surface with a camera to determine the quality.

However, since the bulb contact surface is composed of multiple tapered surfaces with different angles, strong reflection is always returned no matter which direction the light is applied. Therefore, there is a problem that halation occurs and it is difficult to obtain a clear image. Further, although the light hits the upper side of the bulb contact surface, there is a problem that the light does not reach the depth of the hole sufficiently and the image becomes dark and it is difficult to judge the quality.

Therefore, the present inventors have considered inserting a reflective plug into the slide hole of the bulb and reflecting the illumination light with this reflective plug so that the light reaches the depth of the hole on the bulb contact surface. Since it is necessary to insert it in the center of the slide hole, it has been found that there is a risk of damaging the slide hole machined with high precision. In addition, it is necessary to insert the reflective plug, take a picture of the bulb contact surface, and then take out the reflective plug, and move the lighting device installed above the bulb contact surface to insert and remove the reflective plug. It turned out that there was a problem that the cycle time of the inspection could not be shortened because it was also necessary.

Japanese Unexamined Patent Publication No. 2018-115866

Therefore, an object of the present invention is to solve the above-mentioned conventional problems and to provide a valve contact surface inspection method and an inspection device capable of efficiently inspecting the valve contact surface without damaging the surroundings.

In the method for inspecting the bulb contact surface of the present invention, which has been made to solve the above problems, the bulb contact surface of the engine is indirectly illuminated by a hemispherical dome illuminator, and an opening provided in the ceiling of the dome illuminator is opened. A reflective plug provided at the lower end of the shaft that has been penetrated is inserted in the center of the bulb contact surface to illuminate the inside of the bulb contact surface, and the bulb contact surface is photographed by a camera placed above the opening to hit the bulb. It is characterized by inspecting surface defects.

Further, the bulb contact surface inspection device of the present invention made to solve the above problems is provided on a hemispherical dome illuminator that indirectly illuminates the bulb contact surface of the engine from above the engine and on the ceiling of the dome illuminator. A shaft that penetrates the provided opening and extends toward the bulb contact surface, a reflective plug provided at the lower end of the shaft that illuminates the inside of the bulb contact surface, a camera placed above the opening, the shaft, and reflection. It is characterized by having a rotation mechanism for rotating the plug.

It is preferable that a cylinder rotated by the rotation mechanism is provided above the opening, and the shaft is held at the center of the cylinder by a holder. Further, it is preferable that the holder is a wire, a thin plate in the axial direction of the cylinder, or a member made of a transparent material.

According to the present invention, an opening is formed in the ceiling of a hemispherical dome illuminator that indirectly illuminates the bulb contact surface of the engine, and a reflective plug is held at the tip of a shaft that penetrates the opening and extends toward the bulb contact surface. By placing the dome illuminator above the bulb contact surface of the engine, the reflective plug can be located inside the bulb contact surface. Since the light rays from the dome illuminator are reflected by this reflective plug and reach the depth of the bulb contact surface, the entire bulb contact surface can be photographed and inspected by a camera placed above the opening.

According to the present invention, since the reflective plug is provided at the lower end of the shaft extending downward from the dome illuminator, the step of inserting and removing the reflective plug is unnecessary when performing an inspection. Therefore, the inspection cycle time can be shortened. Further, since the reflective plug is provided at the lower end of the shaft, it is not necessary to hold it in the slide hole portion, and since it is in a non-contact state with the engine block, there is no risk of damaging the slide hole portion.

In the present invention, a support for holding the shaft at the center of the opening of the dome illuminator is indispensable, and it is inevitable that this support is transferred to the image of the camera. However, by rotating the shaft to change the direction of the support, the entire valve contact surface can be inspected without any trouble. This point will be described later.

It is sectional drawing which shows the embodiment of the inspection apparatus of this invention. It is a perspective view which shows the support. It is explanatory drawing which shows the change of the image by the height of the upper end of a shaft. It is an image in which the support is rotated. It is explanatory drawing of the dimension position relation. It is an image when the distance between CD is short. It is an image when the distance between CD is separated.

FIG. 1 is a cross-sectional view showing an embodiment of the inspection device of the present invention, in which 10 is an engine block, 11 is a slide hole portion of a valve formed in the engine block 10, and 12 is formed at the upper end of the slide hole portion 11. It is the contact surface of the valve. As described above, the valve contact surface 12 is composed of a plurality of tapered surfaces having different angles. In FIG. 1, the slide hole portion 11 and the valve contact surface 12 are formed so as to be slightly inclined with respect to the upper surface of the engine block 10.

Reference numeral 20 is a base of an inspection device installed on the upper surface of the engine block 10. The base 20 may be placed on the upper surface of the engine block 10, but it can also be held at a position close to the upper surface of the engine block 10 or in close contact with the upper surface of the engine block 10 by a robot hand or the like.

The base 20 is provided with a hemispherical dome illuminator 21. The dome illuminator 21 is provided with a light source 22 such as a light emitting diode on the peripheral edge thereof, and reflects light rays emitted upward from the light source 22 on the inner surface of the dome to perform indirect lighting. As shown in FIG. 1, since the dome illuminator 21 is placed directly above the bulb contact surface 12 to be inspected, the bulb contact surface 12 can be evenly and indirectly illuminated from the entire circumferential direction. However, as described above, the dome illuminator 21 alone cannot sufficiently illuminate the depth of the bulb contact surface 12.

A cylinder 23 is provided above the dome illuminator 21. The cylinder 23 is rotatably supported by a bearing 24 provided on the base 20, and meshes a gear 25 fixed to the cylinder 23 with a drive gear 27 driven by a motor 26 fixed to the base 20. Thereby, it can be rotated by an arbitrary angle. As shown, the axis of rotation is tilted by the same angle as the slide hole portion 11. An opening 28 is formed in the upper part of the dome illuminator 21 at the same position as the cylinder 23. The opening 28 is a round hole having substantially the same diameter as the cylinder 23.

At the center of the cylinder 23, a rod-shaped shaft 29 extending toward the valve contact surface 12 is supported. As shown in FIG. 2, the shaft 29 is supported by the cylinder 23 by a support 30 made of a thin plate parallel to the axis of the cylinder 23. In order to stabilize the position of the shaft 29, it is preferable that the support 30 is provided parallel to the upper surface and the lower surface of the cylinder 23. In addition to the thin plate, the support 30 may use a wire.

A reflective plug 31 is provided at the lower end of the shaft 29. The reflection plug 31 is shallowly inserted inside the bulb contact surface 12 while being supported by the shaft 29, and exhibits a role of reflecting the illumination light from the dome illuminator 21 to illuminate the inside of the bulb contact surface 12. In FIG. 1, a truncated cone-shaped block is shown as the reflective plug 31, but the shape of the reflective plug 31 may be cylindrical. Since the reflective plug 31 is rotated, it is desirable to have an axisymmetric shape.

A camera 32 is attached downward above the opening 28 of the dome illuminator 21. The camera 32 is fixed to a support arm 34 extending upward from the base 20 so that the bulb contact surface 12 can be photographed from the inside of the cylinder 23 and the opening 28. Due to the combination of the reflective plug 31 and the dome illuminator 21, the surface of the bulb contact surface 12 is softly illuminated by the indirect lighting of the dome illuminator 21, and the inside of the bulb contact surface 12 is illuminated by the reflective plug 31 from the dome illuminator 21. It reflects and illuminates the light. Therefore, the camera 32 can capture the entire bulb contact surface 12 as a clear image without halation.

The diameter of the reflection plug 31 is determined so that the light beam can be reflected to the inside of the bulb contact surface 12 and uniformly reflected. Since the reflective plug 31 is reflected in the central portion of the bulb contact surface 12, it is not preferable to increase its diameter.

Further, in the present invention, since the shaft 29 and its support 30 are present between the lens 33 of the camera 32 and the bulb contact surface 12, it is inevitable that these are reflected in the image of the camera 32. In particular, the influence of the support 30 located closest to the lens 33 becomes large. However, this problem can be avoided by the following three means.

The first means is to select a thin plate or wire as the support 30 that does not obstruct the field of view as much as possible. In this embodiment, a thin plate is used in the axial direction of the cylinder 23. The plate thickness and wire diameter are appropriately in the range of 1 to 3 mm. In addition to these wires or a thin plate in the axial direction of the cylinder 23, a member made of a transparent material can also be used.

The second means is to use a lens 33 having a long focal length for the camera 32 and to take a large distance between the upper end of the shaft 29 and the lens 33. As a result, the support 30 at the upper end of the shaft 29 is captured in an out-of-focus state. If the distance between the upper end of the shaft 29 and the lens 33 is short, the reflection range of the upper end of the shaft 29 becomes large as shown in FIG. 3 (A). By increasing this distance, it is shown in FIG. 3 (B). As described above, the reflection range at the upper end of the shaft 29 is narrowed. Even if this is done, an image that is out of focus remains in the center of the image, but since it is the valve contact surface 12 around the image that is desired to be inspected, there is no problem.

The third means is to change the direction of the support 30 by rotating the cylinder 23, and to shift the position of the support 30 reflected in the image of the camera 32. For example, as shown in FIG. 4, after taking an image in which the support 30 is reflected in the horizontal direction, the cylinder 23 is rotated by a motor 26 by 90 ° to take an image in which the support 30 is reflected in the vertical direction. The portion hidden by the support 30 of the contact surface 12 is clearly photographed in the next image. Therefore, by synthesizing these two images, it is possible to obtain a clear image of the entire circumference of the valve contact surface 12.

Next, a preferable dimensional and positional relationship will be described with reference to FIG.
The position of the bulb contact surface 12 is A, the position of the ceiling of the dome illuminator 21 is B, the position of the upper end of the shaft 29 is C, the position of the camera lens 33 is D, and the diameter of the shaft 29 is E. ..
The position A of the valve contact surface 12 is fixed by the valve contact surface of the cylinder head of the engine. Since the dome illuminator 21 selects uniform lighting such that the valve contact surface 12 of the engine head cannot be halated and shadows cannot be formed, the radius of the hemispherical dome is determined and the position of B is also determined. The length of the cylinder 23 arranged just outside the position B is preferably about 30 to 80 mm.

The diameter E of the shaft 29 should be as small as possible so as not to obstruct the field of view as much as possible, but it is desirable that the diameter E be 3 to 6 mm in order to fix the reflective plug 31 so as not to cause runout.

As described above, if the distance between the position C of the upper end of the shaft 29 and the position D of the lens 23 is too short, the upper end of the shaft 29 greatly obstructs the field of view of the camera and obstructs the field of view of the camera. On the contrary, if the distance is increased, it becomes less likely to obstruct the field of view, but the entire device becomes taller and difficult to handle. Therefore, it is preferable that the distance is such that the required valve contact surface 12 does not cover the field of view, and it is desirable that the distance is about 100 to 200 mm. FIG. 6 shows an actual image when the distance between CD and CD is too close, and FIG. 7 shows an actual image when the distance between CD and CD is appropriate. In FIG. 7, since the image of the upper surface of the shaft 29 is within the range of the image of the reflective plug 31, there is no problem in inspecting the valve contact surface 12 around the image.

As described above, according to the present invention, by appropriately setting the dimensional and positional relationship, the inside of the bulb contact surface 12 is uniformly illuminated without contacting the reflective plug 31 with the engine block 10, and the bulb contact. The entire surface 12 can be inspected efficiently.

10 Engine block 11 Valve slide hole 12 Valve contact surface 20 Base 21 Dome illuminator 22 Light source 23 Cylindrical 24 Bearing 25 Gear 26 Motor 27 Drive gear 28 Opening 29 Shaft 30 Support 31 Reflection plug 32 Camera 33 Lens 34 Support arm

Claims (4)

A hemispherical dome illuminator indirectly illuminates the bulb contact surface of the engine, and a reflective plug provided at the lower end of the shaft that penetrates the opening provided in the ceiling of this dome illuminator is inserted into the center of the bulb contact surface. A method for inspecting a bulb contact surface, which comprises shining light on the inside of the bulb contact surface, photographing the bulb contact surface with a camera arranged above the opening, and inspecting a defect on the bulb contact surface. A hemispherical dome illuminator that indirectly illuminates the bulb contact surface of the engine from above the engine, a shaft that penetrates the opening provided in the ceiling of the dome illuminator and extends toward the bulb contact surface, and the lower end of this shaft. An inspection device for a bulb contact surface, which comprises a reflection plug provided to illuminate the inside of the bulb contact surface, a camera arranged above the opening, and a rotation mechanism for rotating the shaft and the reflection plug. The valve contact surface inspection device according to claim 2, wherein a cylinder rotated by the rotation mechanism is provided above the opening, and the shaft is held at the center of the cylinder by a holder. The valve contact surface inspection device according to claim 3, wherein the holder is a wire, a thin plate in the axial direction of the cylinder, or a member made of a transparent material.

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