JPH06235676A - Pressure leak inspection system for hermetically sealed vessel - Google Patents

Abstract

PURPOSE:To provide a pressure leak inspection system of such type as an object to be inspected is immersed into a water tank, pressurized air is fed therein, and leaky state is determined based on bubbles being generated, in which generation of bubbles can be detected automatically with no hindrance of waving of a water surface or illumination. CONSTITUTION:The pressure leak inspection system comprises an illuminator 3 for illuminating an object 2 immersed into a water tank 1 from the side face thereof, an inspection camera 4 for imaging the object 2, and means 5 for processing the image taken by means of the camera 4 wherein the image processing means 5 compares two still images taken by means of the camera within a relatively short time and recognizes any difference between two still images as representative of pressure leak.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure leak suitable for inspecting airtightness and watertightness of vehicle box parts assembled by welding steel plates such as fuel tanks and exhaust silencers for automobiles. The present invention relates to an inspection device.

[0002]

2. Description of the Related Art Conventionally, a pressure leak inspection of a vehicle box body component is performed by sealing an object to be inspected, immersing the object in a large water tank, and then supplying compressed air to the inside through a ventilation pipe. The presence / absence of bubbles in the cracked portion due to processing is visually checked from the water surface.

[0003]

However, it is difficult to accurately inspect a large amount of objects to be inspected by human eyes, and further, when the objects to be inspected are immersed in a water tank, the objects to be inspected are visually observed from the water surface. The water surface tends to swell, and indoor lighting and one's face are reflected on the water surface, which causes bubbles to be overlooked.

[0004]

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems and to obtain an apparatus for highly accurate pressure leak inspection. The object to be inspected immersed in water in a water tank is viewed from the side. An illumination fixture for illuminating, an inspection camera for taking an image of an object to be inspected, and an image processing unit for processing an image taken by the camera, the image processing unit being taken by the camera in a relatively short time. Another feature is that it has a function of comparing two still images and determining whether or not there is a difference between the images.

[0005]

The object to be inspected immersed in the water tank is illuminated from the side, at least two images of the object to be inspected are taken within a relatively short time by the inspection camera, and they are processed by the image processing means including the computer. In contrast, when bubbles are generated in the inspected object on the two images or the generated bubbles grow, or when they rise up apart from the inspected object, the existence of these changes is judged and pressure leaks to the box parts. It is displayed by a display or an alarm.

[0006]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the illustrated embodiments. In the figure, 1 is an inspection water tank, and there is an object to be inspected 2
A steel plate shell of a barrel automotive catalyst muffler is sealed by covering the openings at both ends and immersed by an industrial robot R. Three
Is a lighting lamp, 4 is a video camera as an inspection camera,
The output of the inspection camera 4 is connected to the image processing means 5 including a computer. The optical axes of the illuminating lamp 3 and the camera 4 are directed toward the inspection object 2 at different angles with respect to the horizon, and the light of the illuminating lamp 3 is reflected by the viewing window 1a and the surface of the inspection object 2 to the camera 4. It avoids being reflected. That is, the two arrows in FIG. 1 respectively indicate the optical axes that come out of the illumination lamp 3 to reach the inspection object 2 and are reflected from there to the camera 4.

The inspection water tank 1 is in the shape of a relatively tall rectangle having an open top surface, and the inner surface thereof is coated with black to prevent light reflection. Also, aquarium 1
A peep window 1a in which transparent glass is fitted is opened on one side wall so that the inner surface can be seen.

The inspected object 2, which is an automobile catalyst muffler, is
The box-shaped half portions 2a, 2b made of a pair of left and right steel plates are superposed at the flange portion, and the periphery of the flange portion is welded over the entire circumference, and is formed in a substantially tubular shape with both ends open. Then, at the time of inspection, the above-mentioned opening is closed, and about 1.5 Kg / cm ² is put inside.
The compressed air is sent, and the inspection object 2 is inspected for cracks or defective welding depending on the presence of air leaking from the compressed air.

The image processing means 5 performs image processing according to the flow chart shown in FIG. 2 to capture and display the bubbles generated in the inspection object 2. That is, when the inspection starts, the camera 4 captures and records a still image of the inspection object 2. Then 2
Approximately 3 seconds later (DELAY), the lighting, camera, or inspected object is not moved, and another still image is taken and recorded II.

The image processing means 5 time-differentiates these two images, and if there is a difference between the two images, extracts only the difference and outputs a difference signal. Therefore, if there is no difference due to the presence or absence of the difference signal, the inspected object is judged to be a good product,
If there is a difference, that is, if it is recorded that a bubble that had not existed before, a bubble that has been attached has grown, and that the bubble has floated away from the object to be inspected, the difference signal is recorded. Is generated and it is determined that the welding is defective. The judgment result is displayed on either an OK lamp or a welding failure lamp, and the difference signal is displayed on, for example, a cathode ray tube display (not shown) so that a defective location can be visually confirmed. is there.

Therefore, this pressure leakage inspection device is used in the water tank 1.
Since the inspection object 2 is monitored from the side of the water tank by the viewing window 1a provided on the side, even if there is some waviness on the water surface, or if something is floating on the water surface, it may cause an inspection error. There is no. That is, even if dust sticks to the peep window 1a and it is captured by the camera 4, it does not move, so that it does not cause an inspection error. Further, since the inspection itself is not done artificially because it depends exclusively on the machine, it is possible to avoid judgment errors due to fatigue and habituation of the inspector. Furthermore, the inspection data is recorded and stored by a magnetic recording device or printer. Therefore, it can be used as a basis for quality assurance.

[0012]

As described above, according to the present invention, the two still images obtained by the camera 4 are processed by the image processing means including the computer and compared, and the defect is found, so that the inspection is conducted visually. Compared to the case, human error due to fatigue and habituation is eliminated and accurate test results can be obtained. Also,
Still images taken by the camera 4 are photographed from the side of the aquarium through the viewing window 1a, so that it is possible to solve the problem that the presence of air bubbles is apt to be mistakenly recognized due to indoor lighting on the water surface or waviness on the water surface, as compared with the case of inspecting from the water surface. Have an effect.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of an inspection device.

FIG. 2 is a flowchart of the image processing apparatus.

[Explanation of symbols]

 1 --- inspection water tank, 1a --- peep window, 2 ---- inspection object, 3 ---- illumination lamp, 4 ---- inspection camera, 5 ---- image processing means,

Claims (3)

[Claims] 1. A lighting device for illuminating an object to be inspected immersed in water in a water tank from a side, an inspection camera for taking an image of the object to be inspected, and an image processing means for processing an image taken by the camera. The image processing means has a function of comparing two still images taken by the camera in a relatively short time and determining whether or not there is a difference between the images. Leak inspection device. 2. When the two still images processed by the image processing means have a difference, the difference portion can be displayed on a display.
An apparatus for inspecting pressure leakage of a sealed container according to the item. 3. The sealed container according to claim 1, wherein when there is a difference between the two still images processed by the image processing means, a signal indicating that fact is output. Pressure leak inspection device.