JP2000310579A - Can leakage detection method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent erroneous detection by preventing erroneous detection due to can leakage, making accurate continuous detection operation, drastically increasing the working efficiency of an airtightness inspection, and at the time preventing even a small bubble from being mistaken as dust, utilizing a natural phenomenon where air bubbles rise in hot water, and performing capturing as a specific image that is longer than is wide by image processing by continuous shooting or exposure time adjustment. SOLUTION: A carrier line consisting of a conveyor c for continuously carrying a number of aerosol cans (a) is provided at the bottom part of a hot water bath 1, a box 3 with a lighting mechanism 2 being arranged toward one aerosol can (a) being immersed in hot water in the carrier line is submerge under the hot water surface, a camera 5 for shooting a lighting region below the low water surface by the lighting mechanism 2 from a transparent side surface wall 4 formed under the water surface of the box 3 and a decision part 6 for processing an image signal being detected by the camera 5 are provided, and at the same time a dry circulation mechanism 7 for supplying and unloading a dry cold gas is provided in the box 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is to perform an accurate and safe inspection of the airtightness of cans containing gas such as aerosol cans and fuel cans for cosmetics and pesticides, and other pressure vessels. The present invention relates to a method and apparatus for inspecting can leaks.

[0002]

2. Description of the Related Art Conventionally, gas leakage inspection of a gas-sealed structure such as an aerosol can is performed by visually detecting air bubbles from an inspection object immersed in warm water of a predetermined temperature, thereby obtaining airtightness of the inspection object. However, in the manual inspection of gas leaks by hand, many quality complaints occur due to oversight due to the limitation of human ability. In particular, failure detection by manual work is often overlooked due to sleepiness from the temperature environment and working condition of the hot tub, oversight due to much fatigue and lack of visibility due to steam. There is a demand for high inspection accuracy without erroneous detection of work.

[0003]

For this reason, it is possible to observe the presence or absence of air bubbles from the inspection object of the gas sealing structure by an optical detection mechanism without visual observation, that is, a transparent box provided with a television camera. It has been proposed that a camera detects bubbles trapped at the bottom of a transparent box immersed under the water surface above an object to be inspected (Japanese Patent Laid-Open No. 61-148338). However, when the gas enclosed in a can, such as an aerosol can, is heated by hot water and expands, the gas leaks from the sealing portion and other defects into the hot water and is observed as bubbles. The lens was fogged and could not be accurately detected, resulting in erroneous detection.Also, the detection accuracy decreased due to the adhesion of liquid dust on the glass surface of the transparent box, and small bubbles were continuously attached to the glass surface at the bottom of the box. Inspection cannot be performed, work efficiency will be reduced, and microbubbles may be mistaken for white dust.When lighting is directed toward the camera, light will directly enter the camera and stable brightness will be displayed on the image. There has been a problem that it is not sufficiently satisfactory in reliability, for example, it is impossible to accurately detect bubbles without entering.

SUMMARY OF THE INVENTION The present invention is intended to easily eliminate these conventional drawbacks, so that there is no erroneous detection due to can leak, continuous detection work can be performed accurately, and the operating rate of airtightness inspection of cans can be greatly increased. It is possible to prevent erroneous detection of bubbles and dust by performing continuous shooting and image processing by adjusting the exposure time by utilizing the rising motion of bubbles, thereby improving the reliability in quality. An object of the present invention is to provide a useful method for inspecting leakage of cans such as an aerosol can and the like.

[0005]

According to the present invention, an illuminating region is formed by irradiating an illuminating light below the surface of a warm water above a can to be detected which is immersed and conveyed in warm water, and the illuminated region is formed in the illuminating region. The bubbles leaking from the detection can are raised as white bubbles by the illumination light, and the trajectory rising into the warm water is captured as a straight line image by a camera, and this image signal is taken into the judgment unit and processed to perform image processing to check the airtightness of the can. I do. Further, the present invention is an inspection device for detecting the airtightness of a can by inspecting air bubbles leaking from a detected can immersed in hot water in a hot water tank, wherein the can is immersed in hot water. A box provided with a lighting mechanism arranged toward the bottom, immersed under the hot water surface, and a camera for photographing an illumination area under the hot water surface by the lighting mechanism from a transparent side wall formed in the box; And a drying circulating mechanism that supplies and exhausts a drying gas into and from the box.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In an embodiment of the present invention, an aerosol can of a can to be detected which is immersed and conveyed by conveyance means, for example, a conveyor or other conveyance members, in warm water adjusted to a predetermined temperature (50 to 60 ° C.). C in a hot water tank with a transfer line
The box containing the CD camera is immersed under the surface of warm water, illumination light is applied from the lighting mechanism toward the aerosol can, and the illuminated area in the warm water is continuously photographed from the side with a CCD camera, so that the inside of the warm water is immersed. The image is taken into the judgment unit and the presence or absence of air bubbles leaking from the aerosol can is inspected.When a gas leakage defect is detected, a stop signal is issued to the aerosol can transport process so that defective products can be eliminated. It can prevent erroneous inspection without visual inspection of the operator and can automatically detect the airtightness of the aerosol can in the hot water tank, greatly improving the operation rate of gas leak inspection work. it can.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described with reference to the embodiment shown in FIG. 1. A transportation line comprising a conveyor c for continuously transporting a large number of aerosol cans a via a holder b is provided at the bottom of the hot water tank 1.
A box 3 provided with an illumination mechanism 2 disposed, for example, above, toward one aerosol can a immersed in warm water in the transport line is provided so as to be immersed below the surface of the warm water.
A camera 5 for photographing an illumination area under the warm water surface by the illumination mechanism 2 from the transparent side wall 4 formed under the water surface, and a determination unit 6 for processing an image signal detected by the camera 5; The box 3 is provided with a drying circulation mechanism 7 for supplying and discharging a dry cooling gas, for example, a dry cooling air, to serve as an aerosol can leak inspection apparatus.

The box 3 is a closed box that circulates dry cooling air of a dry gas to dehumidify the inside of the box 3 to prevent the transparent side wall 4 and the lens of the camera 5 from fogging and water from entering. Further, a box 3 which prevents the temperature of the camera 5 from rising and is provided above the aerosol can a conveyed into the hot water tank 1 and below the surface of the hot water,
The hot water tank 1 is provided so as to be movable up and down by a positioning device, for example, a cylinder 8 and other moving mechanisms, and to be movable on a guide rail 9. The transparent side wall 4 facing the camera lens of the camera 5 disposed in the closed box 3 is a back screen of a light shielding wall provided on the back side of the conveyor c of the aerosol can transport mechanism disposed in the hot water tank 1. 10 is provided so as not to affect the image due to the irregular reflection of light, to raise bubbles captured by the illumination light in the illumination area as white bubbles, and to make the trajectory rising in the warm water a vertically long straight line. Even small bubbles can be reliably detected as a captured image, and black dust and the like are not detected, helping to prevent erroneous detection. The conveyer c for transporting the aerosol cans may be provided with a single line or a plurality of lines in the hot water tank 1, or a predetermined heating process path for cans to be carried in a meandering line in hot water. Can be.

Irradiation of the illumination light from the illumination mechanism 2 is effective, for example, when air is emitted from above the water surface to raise bubbles. Further, the back screen 10 in the illumination area has a black or dark color to prevent light reflection. The screen may be selected and used, and a partition plate (not shown) may be provided in the upper part of the hot water tank 1 in order to prevent erroneous detection due to waving or vertical movement of hot water in the illumination area. Still further, for bubble photographing, it is also possible to adopt a mode in which a head plate is provided inclined at about 45 degrees and image processing is performed by a camera via the head plate.

The box 3 is a light-shielding box. A transparent side wall 4 such as a glass plate is provided on one side below the water surface, and a camera 5 is moved on a slide rail 15 at the bottom of the box 3. The camera can be arranged freely so as to be able to contact and separate from the transparent side wall 4, so that the camera 5 can be arranged at an appropriate position. By irradiating the light from the illumination mechanism 2 from above to the air bubbles themselves, and by preventing direct light from shining on the camera 5, the air bubbles d are complemented as whitish bubbles to facilitate image processing. , To improve the detection accuracy. In this case, when performing image processing on the bubble d, since the minute bubble is easily mistaken for white dust, the bubble d uses the natural phenomenon of rising in warm water to perform two or more continuous shootings with the camera 5 or adjustment of the exposure time. Is performed so as to eliminate erroneous detection such as dust.

The transparent side wall 4 of the box 3 is
Although the glass plate is provided in a vertical state, it may be provided in a slightly inclined state in order to prevent bubbles from adhering to the glass surface and within a range that does not interfere with the camera lens.
Further, the illumination mechanism 2 may be provided with a light shielding wall so that illumination light does not directly hit the camera 5, and may be in a state of communicating with the box 3 in a ventilation manner to have a waterproof cooling effect.

Further, the camera 5 can be freely moved through the box 3 and is mounted and set at a position where the camera 5 does not come into contact with an object to be detected (workpiece) so that an illumination area (detection area) can be set freely. is there. For example, the mounting member can be moved not only in the horizontal direction but also in the height direction, or can be moved in an inclined and diagonal direction. In the embodiment, a defective can discharging mechanism (not shown) after the inspection can be provided as needed, and an abnormal signal or display can be provided instead of the defective can discharging mechanism, or can be added together.

The aerosol can a is carried into the hot water tank 1 by the conveyor c, is guided under the surface of the hot water and moves in the immersion state, and is continuously imaged by the camera 5 in the box 3 in the camera area. The aerosol can a, which has been processed and inspected and inspected, is transported from the hot water surface to the hot water tank 1 as it is, carried out of the tank, and sent to the next step. In this hot water tank 1, the illumination mechanism 2 provided in the box 3 irradiates illumination light from above to the aerosol can a in the hot water, and the CCD camera 5 in the box 3 continuously feeds the hot water from the side of the hot water. The image of the moving bubble is taken vertically into the processing determination unit 6 and inspected.
Since the presence or absence of gas leakage is inspected, image processing can be performed very easily without erroneous inspection.

The inspection accuracy can be freely set according to the camera area and the number of cameras.
mm x 105 mm and the camera shutter speed is 1
Assuming that a bubble having a diameter of 1.0 mm rises by about 5.0 mm in 1/60 second, the image processing of the bubble is 22 (5 × 22 pixels). When a pixel having a size of (1 × 22) pixels or more is determined to be defective, a bubble of 0.2 mm can be detected.
Note that a stop signal is sent to the transport process when a leak failure is detected,
In addition, an alarm display signal is output, and the discharging process is performed by manual or automatic discharging means. Although the capacity can be changed depending on the state specification of the product, the processing capacity is generally 200 to 300.
Processing can be performed at a rate of one piece / minute, and productivity can be increased.

Since the CCD camera 5 is often affected by temperature and humidity, it is housed in the closed box 3 and circulates a cooling gas for drying to prevent cooling and humidification, so that the camera environment is always kept constant. Since the camera 5 can accurately detect bubbles and the distance from the camera lens to the image object is required, the accuracy of photographing is not lost due to liquid leakage from the can or dirty water from the can. By bringing the box 3 closer to the bubble generating position, it is possible to prevent the detection accuracy from being lowered due to hot water contamination.

In the figure, 12 is an air supply pipe, 13 is an air exhaust pipe, and 14 is a mounting member.

Although the embodiment has been described with respect to an application example of the gas leak inspection of an aerosol can, an airtightness inspection or a pinhole detection of cans filled with gas such as a fuel can or other pressure vessels. Can also be performed.

[0018]

According to the present invention, a box provided with an illumination mechanism arranged toward a can immersed in warm water is provided so as to be immersed under the surface of the warm water, and the illumination mechanism is provided from a transparent side wall formed in the box. A camera for photographing an illumination area below the hot water surface, a determination unit for processing an image signal detected by the camera, and a drying circulation mechanism for supplying and exhausting a drying gas in the box. This eliminates erroneous detections due to can leaks, enables continuous detection work to be performed accurately, greatly increases the operating rate of airtightness inspection of cans, and utilizes continuous movement of air bubbles to increase continuous shooting and exposure time. By performing the image processing by the adjustment, it is possible to prevent erroneous detection of bubbles and dust, and to improve the reliability in quality. According to the present invention, the transparent side wall facing the camera lens of the camera disposed in the box is opposed to the back screen of the light shielding wall provided on the back side of the aerosol can transport mechanism disposed in the hot water tank. By doing so, the effect of irregular reflection of light on the image is not affected, the bubbles captured by the illumination light are raised as white bubbles, and the trajectory rising in the warm water is captured as a vertically long straight line image ,
Even fine bubbles can be reliably detected, and blackish dust and the like are not detected. This contributes to prevention of erroneous detection, greatly improving inspection accuracy, and providing a reliable and safe inspection apparatus.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Hot water tank 2 Lighting mechanism 3 Box 4 Transparent side wall 5 Camera 6 Judgment part 7 Drying circulation mechanism 8 Cylinder 9 Slide rail 10 Back screen 12 Air supply pipe 13 Air exhaust pipe

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2G067 AA46 BB17 DD15 5B057 AA01 CA02 CA08 CB02 CB06 CC01 CE12 CE15 CH20 DA03 DB08

Claims (6)

[Claims] An illumination area is formed by irradiating illumination light below a surface of a hot water above a detection can to be immersed and conveyed in hot water,
In the illumination area, bubbles leaking from the detected can are raised as white bubbles by the illumination light, and the trajectory rising into the warm water is captured by a camera as a straight line image. Inspection method for inspecting the airtightness of cans. 2. The method according to claim 1, wherein the image captured by the camera is image processing performed by two or more continuous shootings or by adjusting an exposure time. 3. An inspection device for detecting airtightness of a can by inspecting air bubbles leaking from a detection can immersed in hot water in a hot water tank. A box provided with a lighting mechanism disposed under the hot water surface, and a camera for photographing an illumination area under the hot water surface by the lighting mechanism from a transparent side wall formed in the box; and a camera detected by the camera. And a determination unit for processing the image signal, and a drying circulating mechanism for supplying and discharging a drying gas into and from the box. 4. The can leak inspection apparatus according to claim 3, wherein the box is a closed box, and is provided in the hot water tank so as to be movable below a hot water surface above the aerosol can conveyed into the hot water tank. . 5. The box has a transparent side wall facing a camera lens of a camera disposed in the box and a light shielding wall provided on a back side of an aerosol can transport mechanism disposed in a hot water tank. The can leak inspection device according to claim 3 or 4, which is provided. 6. The box according to claim 3, wherein the box is a light-shielding box, and a camera is movably provided at a bottom portion in the box so that the camera can be brought into contact with and separated from a transparent side wall. Can leak inspection equipment.