JP2021192004A - Method for inspecting airtightness of container, and inspection apparatus therefor - Google Patents

Abstract

To provide a method for inspecting the airtightness of a container and an apparatus therefor that can automatically carry out inspection with good accuracy and can be applied to a manufacturing line used for manufacturing various types of containers.SOLUTION: A method for inspecting the airtightness of a container of the present invention includes the steps in which: a trace gas is filled inside a container with an aperture thereof sealed, and a container A is submerged into a predetermined liquid; the upper part of the submerged container A is covered in such a state that a space K is formed so as to hold gas inside a cover 8, with the cover 8 including an aperture 8b in a lower part 8a, a closable upper part 8c, and a detector 9 which can detect the trace gas in the upper part 8c; a liquid current is generated under the surface of the liquid L toward the container A or the inside of the cover 8, and the trace gas, which leaks out of a defective part of the container A and adheres onto the surface of the container A or to the inside of the cover, is pushed out into the space K; and the trace gas being present in the space K is detected by the detector 9.SELECTED DRAWING: Figure 1

Description

The present invention relates to a method for inspecting the airtightness of a container and an inspection device thereof.

For example, in containers that require airtightness such as axle cases and fuel cases, after manufacturing these, inspection is performed to see if there are any defects in the container. Such an airtightness inspection is generally incorporated in the production line from the viewpoint of efficiency. Further, conventionally, when inspecting the airtightness of a container, the inspection apparatus shown in FIGS. 2 and 3 and the methods shown in the following patent documents and non-patent documents have been used.

Japanese Unexamined Patent Publication No. 2006-105736 Japanese Unexamined Patent Publication No. 2017-166909

JIS Z 2330: 2012 Types of leak test methods and their selection Japan Nondestructive Inspection Association Vol. 55, No. 2, 2006

FIG. 2 is a diagram schematically showing a conventional inspection device for inspecting airtightness. The inspection device 101 shown in FIG. 2 inspects the airtightness of the axle case A, and inspects the axle case A by submerging it in a liquid tank 102 capable of containing a predetermined liquid (for example, water). It is a thing. Specifically, the left and right openings in the axle case A are closed by the first sealing mechanism 103, and the central opening is closed by the second sealing mechanism 104. The second sealing mechanism 104 has a function of sending air into the axle case A from the central opening. Then, the axle case A is submerged in the liquid of the liquid tank 102 with the openings sealed by the first sealing mechanism 103 and the second sealing mechanism 104, and the inside of the axle case A is filled with the air sent from the second sealing mechanism 104. Pressurize. If there is a defective portion in the axle case A in this state, air bubbles leak from the defective portion, so the presence or absence of the defective portion is determined by visually confirming the air bubbles by the inspector.

However, in the inspection by such an inspection device 101, if the defective portion is small, the size of the leaking bubbles is also small, so that there is a possibility that the bubbles may be overlooked by visual confirmation. In addition, air may remain in the gaps between the parts attached to the outside of the axle case A, and this air may appear as air bubbles. Therefore, although there are no defective parts, it is judged to be defective. There is also a risk. Furthermore, since it is necessary to complete the inspection within the cycle time of the production line, the burden on the inspector is increasing.

On the other hand, an inspection device that automatically determines the presence or absence of a defective portion without visual confirmation by an inspector is also used. The inspection device 201 shown in FIG. 3 sends trace gas (for example, helium) into the sealed axle case A and detects the trace gas leaking from the defective portion. Specifically, the left and right openings in the axle case A are closed by the first sealing mechanism 203, and the central opening is closed by the second sealing mechanism 204 having a function of sending trace gas into the axle case A. Then, the inside of the axle case A is provided by the detection device (consisting of the detection device main body 205 and the probe 206 connected to the detection device main body 205) and the robot 207 (for example, a 6-axis manipulator) for detecting the presence or absence of trace gas. The probe 206 is scanned by the robot 207 around a portion where a defective portion is likely to exist (for example, a seam of the axle case A) in a state of being pressurized with the trace gas.

However, in such an inspection of the inspection device 201, although the presence or absence of a defective portion can be grasped by detecting the trace gas, it is difficult to grasp the exact position of the defective portion. Therefore, if it is determined that there is a defective part, it is temporarily removed from the production line, the axle case A is submerged in a device as shown in FIG. 2, the position of the defective part is specified by air bubbles, and the defective part is repaired. After that, it is necessary to put it back on the production line and perform re-inspection. Further, since teaching of the robot 207 is required according to the type of the container to be inspected, it takes time to start up the production line. Further, in the axle case A as shown in the figure, the time for scanning the probe 206 with one robot 207 is usually longer than the time for manufacturing the axle case A on the production line. Therefore, in order to shorten the cycle time, it is necessary to prepare a plurality of robots 207 and the like (for example, two robots 207 per production line), which increases the cost required for the equipment.

Since the inspection device shown in Patent Document 1 uses a cover 24 that matches the shape of the container to be inspected, if the shape of the container is different, the cover 24 must also be replaced, and various types of containers must be replaced. It is difficult to apply to a production line for manufacturing, and it lacks versatility. Further, in the inspection apparatus shown in Patent Document 2, the container to be inspected is arranged inside the inspection chamber 3, helium is supplied to the container, and the helium concentration in the inspection chamber 3 is measured, so that the concentration changes. In some cases, it is determined that the container has a defective part. However, the volume of the laboratory 3 becomes large because it needs to surround the entire container, and as a result, the helium concentration in the laboratory 3 does not change immediately, and it takes time to obtain the test result. .. Further, in the inspection devices shown in Patent Documents 1 and 2, the presence or absence of a defective portion can be grasped by a change in the concentration of the trace gas or the like, but the position thereof cannot be specified.

In addition, Non-Patent Documents 1 and 2 also disclose a method and an inspection device for inspecting the airtightness of a container. However, since the plurality of inspection methods shown in Non-Patent Documents 1 and 2 are the same types as those in FIGS. 2 and 3 described above, or are difficult to incorporate into a production line, the inspection devices of FIGS. 2 and 3 are shown. The problem that arises in the above has not been solved.

An object of the present invention is to solve such a conventional problem, and the method and device for inspecting the airtightness of a container are automatically and accurately inspected without depending on the skill of an inspector. The purpose is to provide a technology that can be applied to a production line for producing a wide variety of containers.

The present invention is a method for inspecting the airtightness of a container, in which a container having a closed opening is filled with trace gas and the container is submerged in a predetermined liquid, and an opening is provided at the bottom. A cover provided with a detection device capable of closing the upper part and detecting the trace gas covers the upper part of the submerged container in a state where a space for collecting gas is formed inside the cover. The step and the trace gas leaking from the defective portion of the container and adhering to the surface of the container or the inside of the cover by generating a liquid flow toward the inside of the container or the cover under the liquid surface of the liquid. It is characterized by including a step of pushing the trace gas into the space and a step of detecting the trace gas existing in the space by the detection device.

The step of pushing the trace gas into the space is preferably performed by generating a liquid flow toward the inside of the container and the cover under the liquid surface of the liquid.

Further, it is preferable that the cover has an upper constriction shape in which the upper portion is narrower than the lower portion.

Further, it is preferable that the cover is provided with a gas stirring means for stirring the gas in the space.

Then, when the concentration of the trace gas detected by the detection device is equal to or higher than a predetermined value, or when the concentration of the trace gas detected by the detection device increases with time, the defect is found in the container. It is preferable to include a step of determining that there is a portion.

Further, the present invention is an inspection device for inspecting the airtightness of a container, which is a liquid tank capable of containing a predetermined liquid and submerging the container, and a trace gas feeding device for feeding the trace gas into the inside of the container. A supply means, a cover that covers the upper part of the container submerged in the liquid tank in a state where the upper part can be closed with an opening at the lower part and a space for gas to collect inside, and the liquid tank. A liquid flow generating means for generating a liquid flow toward the inside of the container that is submerged or the cover that covers the upper part of the container, and a liquid flow generating means that is provided on the upper part of the cover and exists in the space. It is also an inspection device characterized by being provided with a detection device that detects trace gas.

According to the present invention, the inspection can be automatically performed by incorporating it into the production line without depending on the skill of the inspector. Moreover, even if the type of container is different, it is not necessary to change the equipment drastically. Further, since it is easy to identify the position of the defective portion in the container, it is possible to repair and re-inspect the defective portion on the spot without removing the container from the production line.

It is a figure which showed typically one Embodiment of the inspection apparatus which concerns on this invention. It is a figure which showed the example of the conventional inspection apparatus schematically. It is a figure which showed the other example of the conventional inspection apparatus schematically.

Hereinafter, a method for inspecting the airtightness of the container according to the present invention and an embodiment of the inspection device will be described with reference to the accompanying drawings.

FIG. 1 is a diagram schematically showing an embodiment of an inspection device according to the present invention. The inspection device 1 of the present embodiment is configured so that the airtightness of the axle case A can be inspected. As will be described later, the inspection device 1 can inspect the airtightness of other axle cases having slightly different shapes without changing the equipment (or with a slight change). Further, the container that can be inspected by the inspection device 1 is not limited to the axle case, and for example, the airtightness of other containers (for example, fuel case, air tank, SCR tank) is inspected by appropriately changing the first sealing mechanism described later. It is also possible.

The inspection device 1 of the present embodiment includes a liquid tank 2, a first sealing mechanism 3, a second sealing mechanism 4, a pump 5, a stirring device 6, an ultrasonic vibration device 7, a cover 8, a detection device 9, and a fan 10. There is.

The liquid tank 2 accommodates a predetermined liquid L, and is formed in a size that allows the axle case A to be submerged. The liquid L contained in the liquid tank 2 is not particularly limited, and for example, water, oil (for example, rust preventive oil), and liquid organic compound (for example, Fluorinert (registered trademark)) are used.

The first sealing mechanism 3 is configured to close the left and right openings in the axle case A. The first sealing mechanism 3 can move forward and backward with respect to the left and right openings of the axle case A, and may automatically close these openings by moving from the retracted position to the forward position, for example. It may be something like a cap that is fitted into the left and right openings by an operator.

The second sealing mechanism 4 is configured to close the central opening of the axle case A. Further, the second sealing mechanism 4 is also referred to as a "trace gas feeding means" in the present specification and the like, and has a function of feeding the trace gas into the axle case A. The first sealing mechanism 3 may have a function of sending trace gas into the axle case A. Examples of the gas used as the trace gas here include, but are not limited to, helium, hydrogen, carbon dioxide, halogen and the like.

The pump 5, the agitator 6, and the ultrasonic vibration device 7 are referred to as "liquid flow generating means" in the present specification and the like, and the liquid L contained in the liquid tank 2 is made to flow to generate a liquid flow. Is. The pump 5 of the present embodiment is directed toward the inside of the first pipe 5a that is directed toward the lower part of the submerged axle case A and the cover 8 that is moved so as to cover the upper part of the axle case A as described later. The inside of the axle case A and the cover 8 is connected to the second pipe 5b to be directed, the liquid of the liquid tank 2 is sucked through the suction pipe 5c, and the liquid is discharged from the first pipe 5a and the second pipe 5b. It is possible to generate a liquid flow toward. Further, in the present embodiment, the stirring device 6 is attached upward at the bottom of the liquid tank 2, and the liquid toward the axle case A by rotating a propeller-shaped rotating body having a plurality of blades (blades). A flow can be generated. The ultrasonic vibration device 7 vibrates the liquid by ultrasonic waves to generate a liquid flow. In the present embodiment, the bottom of the liquid tank 2 and the intermediate portion of the cover 8 (the cover 8 is the axle case A). When it is moved to a position that covers the upper part, the inside of the cover 8 is provided at a portion located below the liquid surface), and a liquid flow toward the axle case A can be generated. The pump 5, the stirring device 6, and the ultrasonic vibration device 7 are examples of the liquid flow generating means, and the liquid L may be flowed by other means. Further, it is not necessary to provide the pump 5, the stirring device 6, and the ultrasonic vibration device 7, and the mounting position and orientation thereof including the first pipe 5a and the like are not limited to the illustrated examples.

The cover 8 has an opening 8b in the lower portion 8a, and a lid portion (not shown) that can be opened and closed is provided in the upper portion 8c. The cover 8 of the present embodiment has an upper constriction shape in which the upper portion 8c is narrower than the lower portion 8a. The opening 8b is wide enough to cover the entire axle case A in a plan view. Further, the cover 8 is configured to be movable in the vertical direction with respect to the liquid tank 2, and moves from a height located above the liquid level of the liquid L to a height covering the upper part of the submerged axle case A. can do. When the cover 8 is moved to a height that covers the upper part of the axle case A, the upper portion 8c is located above the liquid surface, and a space K in which gas collects is formed inside the upper portion 8c. In this embodiment, the volume of the space K is set to about 20 L.

The detection device 9 includes a detection device main body 9a and a probe 9b connected to the detection device main body 9a, and can detect the presence of trace gas at a location where the probe 9b is attached. The probe 9b of the present embodiment is attached to the upper portion 8c of the cover 8 and can detect the trace gas in the space K. The detection device 9 of the present embodiment has a function of determining that the trace gas is present in the space K when the concentration of the trace gas is equal to or higher than a predetermined value when detecting the trace gas in the space K, and the concentration of the trace gas over time. It has a function of determining that the trace gas is present in the space K when the temperature is rising.

The fan 10 is referred to as a "gas stirring means" in the present specification and the like, and is used to stir gas by rotating a propeller-shaped rotating body, for example. The fan 10 of the present embodiment is attached to the inside of the upper portion 8c of the cover 8 and can agitate the gas accumulated in the space K in the space K. The fan 10 is an example of gas stirring means, and the gas in the space K may be stirred by other means.

The inspection device 1 of the present embodiment can inspect the airtightness of the axle case A by the method described below.

First, the left and right openings and the central opening in the axle case A are closed by the first sealing mechanism 3 and the second sealing mechanism 4. Then, the trace gas is sent into the axle case A from the second sealing mechanism 4, and the inside of the axle case A is filled with the trace gas. The pressure of the trace gas is set to be, for example, about 0.07 MPa higher than the atmospheric pressure, and the inside of the axle case A is pressurized by the trace gas. Then, the axle case A is submerged in the liquid L of the liquid tank 2 while being pressurized with the trace gas.

Next, the cover 8 located above the liquid level of the liquid L is lowered to a position covering the upper part of the submerged axle case A. Here, when lowering the cover 8, the lid portion (not shown) provided on the upper portion 8c is opened so that the liquid levels of the liquid L are aligned on the outside and the inside of the cover 8, and after the cover 8 is lowered to a predetermined position. The lid will be closed. As a result, a space K having a predetermined volume of air is formed inside the upper portion 8c.

After that, the pump 5, the stirring device 6, and the ultrasonic vibration device 7 are driven to cause the liquid L to flow, and a liquid flow toward the inside of the axle case A and the cover 8 is generated. Here, if the axle case A has a defective portion, the trace gas in the axle case A leaks from the defective portion and becomes a bubble in the liquid L. Some of these bubbles float as they are toward the water surface facing the space K, while others adhere to the surface of the axle case A or the inside of the lower portion 8a of the cover 8 and stay there. However, in the present embodiment, since the liquid flow toward the inside of the axle case A and the cover 8 is generated, the bubbles adhering to the axle case A and the cover 8 can be washed away and floated on the water surface facing the space K. ..

When the axle case A has a defect portion as described above, the bubbles of the trace gas floating on the water surface facing the space K burst, and the trace gas diffuses in the space K. Here, a probe 9b connected to the detection device main body 9a is attached to the upper portion 8c of the cover 8, and the trace gas in the space K can be detected by the detection device 9 provided with the detection device main body 9a and the probe 9b. .. Therefore, when the trace gas is detected by the detection device 9, it can be seen that the axle case A has a defective portion. In the present embodiment, the time during which the trace gas accumulates in the space K and can be detected by the detection device 9 depends on the performance of the detection device 9, but the cover 8 is moved to a position that covers the upper part of the submerged axle case A. It is about 1 minute after letting it. Further, when the detection device 9 detects the trace gas in the space K, it may be determined that the trace gas exists in the space K when the concentration of the trace gas is equal to or higher than a predetermined value, and the concentration of the trace gas may be determined over time. It may be determined that the trace gas is present in the space K when the temperature is rising.

As shown in the figure, the cover 8 of the present embodiment has an upper constriction shape in which the upper portion 8c is narrower than the lower portion 8a. That is, since the inside of the upper portion 8c is narrower than that of the cube-shaped or rectangular parallelepiped-shaped cover, the volume of the space K can be reduced. Therefore, even if the amount of trace gas leaked from the defective portion is small, the concentration of the trace gas in the space K can be increased as compared with the cover of the cube shape or the like, so that the time required for detecting the trace gas can be shortened. Can be done. Further, since the gas accumulated in the space K can be agitated by the fan 10 provided on the cover 8, the time required for detection can be shortened even if the trace gas has a property of easily staying.

When the trace gas in the space K is detected, the cover 8 is moved with respect to the axle case A. As a result, the location where air bubbles are leaking from the axle case A can be visually identified, so that the axle case A can be pulled up from the liquid L and the defective portion can be repaired on the spot. Can be re-examined.

Further, the inspection device 1 of the present embodiment can collect the trace gas in the space K and detect it if the cover 8 covers the upper part of the container regardless of the shape of the container (axle case A). Other axle cases and other containers (eg, fuel cases, air tanks, SCR tanks) with different shapes can also be inspected for airtightness without (or with minor changes) equipment changes.

Although one embodiment of the present invention has been described above, the present invention is not limited to the specific embodiment, and unless otherwise specified in the above description, the gist of the present invention described in the claims. Various modifications and changes are possible within the range of. Moreover, the effect in the above-described embodiment is merely an example of the effect resulting from the present invention, and does not mean that the effect according to the present invention is limited to the above-mentioned effect.

1: Inspection device 2: Liquid tank 3: First sealing mechanism 4: Second sealing mechanism (trace gas feeding means)
5: Pump (means for generating liquid flow)
5a: 1st pipe 5b: 2nd pipe 5c: Suction pipe 6: Stirrer (liquid flow generating means)
7: Ultrasonic vibration device (liquid flow generating means)
8: Cover 8a: Lower part of cover 8b: Opening 8c: Upper part of cover 9: Detection device 9a: Detection device main body 9b: Probe 10: Fan (gas stirring means)
A: Axle case (container)
K: Space L: Liquid

Claims (7)

It is a method to inspect the airtightness of the container.
The process of filling the inside of a container with a closed opening with trace gas and submerging the container in a predetermined liquid.
The cover is provided with a detection device having an opening in the lower part and capable of closing the upper part and detecting the trace gas in the upper part, and the cover is submerged in a state where a space for collecting gas is formed inside the cover. The process of covering the top of the container and
The trace gas leaking from the defective portion of the container and adhering to the surface of the container or the inside of the cover is generated in the space by generating a liquid flow toward the inside of the container or the cover under the liquid surface of the liquid. And the process of flushing
A method comprising a step of detecting the trace gas existing in the space by the detection device. The method according to claim 1, wherein the step of pushing the trace gas into the space is performed by generating a liquid flow toward the inside of the container and the cover under the liquid surface of the liquid. The method according to claim 1 or 2, wherein the cover has an upper constriction shape in which the upper portion is narrow with respect to the lower portion. The method according to any one of claims 1 to 3, wherein the cover comprises a gas stirring means for stirring the gas in the space. When the concentration of the trace gas detected by the detection device is equal to or higher than a predetermined value, or when the concentration of the trace gas detected by the detection device increases with time, the defective portion in the container. The method according to any one of claims 1 to 4, further comprising a step of determining that there is. Any one of claims 1 to 5, comprising moving the cover with respect to the container and identifying the defective portion by the position of air bubbles leaking from the container under the liquid surface of the liquid. The method described in the section. An inspection device for inspecting the airtightness of containers.
A liquid tank that can contain a predetermined liquid and submerge the container,
A trace gas feeding means for feeding trace gas into the inside of the container,
A cover that has an opening at the bottom and can be closed at the top, and covers the upper part of the container submerged in the liquid tank in a state where a space for collecting gas is formed inside.
A liquid flow generating means for generating a liquid flow toward the inside of the container or the cover that covers the upper part of the container under the liquid surface of the liquid tank.
An inspection device provided on an upper portion of the cover and provided with a detection device for detecting the trace gas existing in the space.

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