JP2004085254A - Leak inspection method and device - Google Patents

Abstract

[PROBLEMS] To provide an inexpensive method and apparatus for performing a leak inspection of a product which can be determined as a non-defective product if the leak is not more than a predetermined minute leak, in addition to a simple setup change time and an inspection time. That is the task.
A chamber (8) comprising a lid part (85) having an air supply port and a cylinder part (86) having an air discharge port, wherein the chamber (8) has a structure in which an inner space is formed by closing the lid part on the cylinder part. By inserting the container 9 to be inspected into the chamber and closing the lid, the interior space of the chamber is changed into a space 83 connected to the air supply port and a space 84 connected to the air discharge port. Using a chamber having a structure that can be separated by a side surface and a bottom surface, when the container 9 to be inspected is sealed in the chamber and air is supplied from the air supply port, the flow rate of air leaking from the air discharge port is measured by a flow meter. The above problem is solved by an inspection method for measuring the presence or absence and the degree of leakage of a container to be inspected by measuring.
[Selection] Fig. 2

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for checking a container such as a paper cup for leaks.
[0002]
[Prior art]
Conventionally, as a method for quantitatively measuring a small leak of a container, there are a differential pressure gauge type (Japanese Patent No. 2700962), a pressure gauge type (Patent No. 3104976, a registered utility model No. 3072863), a different gas detection type, and the like. . In the differential pressure type, the same air pressure is applied from the air source to the container to be inspected and the reference container that does not leak, and after the supply path is cut off, it is determined whether or not there is a pressure difference between the two to determine whether or not there is a leak. The pressure gauge type seals the container by enclosing the container in a chamber that seals the container and measuring the change in air pressure in the space inside the chamber outside the container when a certain pressure is applied to the container from the air source. Check for gender.
[0003]
As another method for inspecting a minute leak of the container, a submerged test (registered utility model No. 3047893) or a case in which the container is sealed in a chamber and compressed air is sealed, and the gas leaking into the chamber is bubbled into the liquid. And a method of observing the presence or absence of the bubbles (Japanese Patent No. 2664196). FIG. 1 schematically shows the inspection method of Japanese Patent No. 2664196. An inspection container 109 is sealed in the chamber 108. The inspection container 109 is supplied with air from the air supply unit 10 through an air supply port 181. The sealed test container 109 separates the internal space of the chamber 108 into a space 183 inside the test container and a space 184 outside the test container on the side and bottom surfaces of the test container. Now, when air is supplied from the air supply port 181, if the inspection container has a pinhole or the like, leakage occurs, the leaked air fills the space 184, and is discharged from the exhaust port 182. The discharge of the air is observed as bubbles in the liquid filled in the liquid tank 120. Therefore, air bubbles are observed by the air supply, and if the air bubbles stop when the air supply is stopped, it can be recognized that the container to be inspected has leaked.
[0004]
[Problems to be solved by the invention]
The above-mentioned differential pressure gauge type (Japanese Patent No. 2700962), pressure gauge type (Japanese Patent No. 3104976, registered utility model No. 3072863), and a different type of gas detection type conventional device have a high equipment cost and require a long inspection time. It has disadvantages such as long. In addition, these methods have the disadvantage that it takes a long time for preparation because conditions such as an optimum pressure set value and an inspection required time have to be determined depending on the difference in the container capacity.
Further, the method of the submergence test (registered utility model No. 3047893) or the method of Japanese Patent No. 2664196 shown in FIG. 1 is to detect the presence or absence of air bubbles by a sensor or by observation to know whether or not there is a leak. In other words, it is a qualitative inspection method, and it is applied not only to whether there is a leak like a paper cup, but also to a leak inspection of a container that can be judged as good if it is less than a certain small leak. Can not.
[0005]
The present invention has been made in consideration of such a problem, and it is not limited to whether or not there is a leak like a paper cup, but a leak of a product that can be determined as a non-defective product if it is less than a predetermined minute leak. It is an object of the present invention to provide an inexpensive method and apparatus for performing an inspection with a short preparation time and a short inspection time.
[0006]
[Means for Solving the Problems]
According to a first aspect of the present invention, there is provided a chamber for enclosing a container to be inspected, an air supply unit for supplying air to the chamber, a flow meter for measuring a flow rate of air flowing out of the chamber, and a tube for connecting the tubes. A leakage inspection device configured by connecting
The chamber has a lid having an air supply port and a cylinder having an air outlet, and has a structure in which a space inside the chamber is formed by closing the lid to the cylinder. The inside space of the chamber is separated into a space connected to the air supply port and a space connected to the air exhaust port by the side and bottom surfaces of the container to be inspected by putting the container to be inspected and closing and sealing the lid. It has a possible structure,
A leakage inspection apparatus for inspecting whether or not the inspection container leaks when the flow meter detects the flow of air when the inspection container is sealed in the chamber and air is supplied from the air supply unit.
[0007]
The leak inspection device grasps the relationship between the size of the pinhole diameter that causes the leak and the flow rate of the leaked air at a constant air supply pressure in advance, so that the container to be inspected can be read from the flowmeter reading. The feature is that it is also possible to estimate the diameter of the pinhole.
[0008]
According to a second aspect of the present invention, there is provided a chamber comprising a lid having an air supply port and a cylinder having an air discharge port, wherein the inner space is formed by closing the lid to the cylinder. In this case, the container to be inspected is placed in the cylindrical portion, and the lid portion is closed and sealed, whereby the chamber internal space is inspected into a space connected to the air supply port and a space connected to the air discharge port. Using a chamber having a structure that can be separated by the side and bottom surface of the container, a method for inspecting the presence or absence of leakage of the container,
When the container to be inspected is sealed in the chamber and air is supplied from the air supply port, the flow rate of air leaking from the air outlet is measured by a flow meter to check whether the container to be inspected is leaking. It is an inspection method.
[0009]
A second aspect of the leak inspection method according to the second invention is to grasp the relationship between the size of the pinhole diameter causing the leak and the flow rate of the leak air at a constant air supply pressure in advance. Accordingly, if the reading of the flow meter is equal to or less than the reference flow rate, the pinhole diameter of the container to be inspected can be estimated to be sufficiently small, and thus the inspection method is determined as a non-defective product.
[0010]
BEST MODE FOR CARRYING OUT THE INVENTION
FIG. 2 shows an apparatus configuration of an inspection apparatus 1 that performs the inspection method of the present invention. This embodiment will be described by taking a paper cup leak test as an example. The apparatus 1 includes an air supply unit 10, a chamber 8 adapted to the shape of the paper cup 9, a tube 14 through which air leaks from the chamber 8, and a flow meter 15 for measuring the flow rate of the leaked air. The chamber 8 is divided into a tube portion 86 and a cover portion 85. The paper cup 9 is put in the tube portion 86, and the mouth portion 91 of the paper cup 9 is sandwiched between the tube portion 86 and the cover portion 85 by closing the cover portion 85. It is fixed and hermetically sealed. In this state, the inside 83 and the outside 84 of the paper cup 9 are reliably partitioned.
[0011]
Next, a method of inspecting a paper cup will be specifically described with reference to the flowchart of FIG. After the paper cup 9 is hermetically sealed in the chamber 8 (S01), air is supplied from the air supply port 81 (S02). The air fills the internal space 83 of the cup formed by the paper cup 9 and the lid 85 in the chamber 8. If there is a leak in the paper cup 9, the side of the chamber 84 outside the paper cup 9 is 84. The air leaks from the chamber, and the leaked air passes through the tube 14 and the flow meter 15 from the chamber outlet 82 and is discharged to the atmosphere from the outlet 16 (S03). Here, the flow of the generated air (leaked air) is measured by the flow meter 15 (S04). If the reading of the flow meter 15 is equal to or less than the reference flow rate, it is determined to be good (S05). The above is the schematic flow of the leak inspection method of the present invention.
[0012]
The leak inspection method according to the present invention does not require setting conditions such as determining the required inspection time, requires a short inspection time, quantifies the leakage flow rate, and compares the leakage flow rate with the reference flow rate. It is characterized in that pass / fail can be determined. Hereinafter, this will be supplementarily described.
[0013]
FIG. 4 shows an example of the reading of the flow meter 15 when air leaks. In FIG. 4, the flow meter 15 detects the flow of exhaust air immediately after opening the valve 12 and starting air supply, and observes a steady-state exhaust flow for an extremely short time t. Therefore, the reading of the flow meter 15 after a very short time t seconds has elapsed since the air supply indicates whether or not the cup 9 has a pinhole that causes air leakage.
[0014]
Since t is determined by the volume of the chamber 8 (the sum of the volumes of 83 and 84), the pressure of the pneumatic source, and the size of the pinhole diameter, regardless of the volume of the cup 9, the time required for the leak inspection is 9 can be determined independently of the volume. In other words, it is not necessary to determine the conditions such as the required leak inspection time according to the volume of the cup.
[0015]
Further, in the steady state, the air pressure applied to the inner surface of the cup 9 is considered to be constant, and the flow rate of the air passing through the pinhole is equal to the flow rate passing through the flowmeter 15 through the tube 14, so that the pinhole exists. In this case, the diameter of the pinhole opened in the cup 9 can be estimated from the reading of the flow meter 15. FIG. 5 is a graph plotting the reading of the flow meter 15 obtained by the magnitude of the pinhole diameter in a constant chamber volume, with the pressure value of the air pressure source 11 on the horizontal axis and the observed flow value on the vertical axis. It is. From the graph of FIG. 5, it can be seen that the leak flow rate increases as the pressurization value increases, and that the larger the pinhole diameter, the larger the leak flow occurs if the pressurization value is constant.
[0016]
FIG. 6 is a graph created from the graph of FIG. 5, and shows the relationship between the size of the pinhole diameter and the generated leakage flow when the pressure value is constant (the pressure value at the right end of the graph of FIG. 5). It is a plot. It can be seen from the graph of FIG. 6 that the pinhole diameter can be estimated from the reading of the flow meter 15. Therefore, for example, when a pinhole having a diameter of not less than amm is determined to be defective and a pinhole having a diameter of less than amm is not determined to be defective, from FIG. 6, if the leakage amount is less than bl / min, it is not determined to be defective. Quantitative leak inspection can be performed.
[0017]
The leak inspection apparatus 1 has been described as the embodiment of the present invention. The features of the leak inspection device 1 are summarized below.
1) By measuring a small leak amount (flow rate) from a hole present in the container, a leak test can be performed instantaneously, and the time required for the test process can be reduced.
2) By measuring the minute amount of leakage (flow rate) from the hole present in the container, it is not necessary to determine the conditions due to the difference in the volume of the container, so that the setup change time is shortened.
3) Since it has a simple structure, a small and inexpensive device can be obtained.
4) Quantitative leak inspection is possible. That is, the pinhole diameter can be estimated from not only whether there is a leak but also the leak flow rate. Therefore, even if there is a small leak, if the predetermined leak amount is not exceeded, it is possible to standardize the quality judgment of the container satisfying the function.
[0018]
【The invention's effect】
As described above in detail, according to the leakage inspection method and the leakage inspection apparatus using the method according to the present invention, it is possible to realize a leakage inspection step in which the time required for setup change is short and the time required for inspection is short. It has a remarkable effect. In addition, not only whether there is a leak but also an inspection process that meets the inspection criteria for determining a good product if the amount of leak is very small, an appropriate inspection method can be implemented without deteriorating quality or safety. Since there is no such product, a product which has been determined to be defective can be correctly evaluated, and a remarkable effect can be obtained in that the non-defective product ratio can be increased and the yield can be improved.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a typical prior art.
FIG. 2 is an overall configuration diagram of a leakage inspection apparatus 1 that realizes a leakage inspection method according to the present invention.
FIG. 3 is a flowchart illustrating an outline of a leakage inspection method according to the present invention.
FIG. 4 is a diagram showing an example of reading of a flow meter 15;
FIG. 5 is a graph showing how the flow rate of generated leak air changes with respect to the pressure value of the pneumatic source 11 according to the pinhole diameter.
FIG. 6 is a graph showing the relationship between the reading of the flow meter 15 and the pinhole diameter when the pressure value of the air pressure source 11 is kept constant.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Leakage inspection apparatus 8 Chamber 9 Paper cup 10 Air supply part 11 Air pressure source 12 Valve 13 Tube 14 Tube 15 Flow meter 16 Outlet 81 Chamber air supply port 82 Chamber air discharge port 85 Chamber lid 86 Chamber cylinder 108 Chamber 109 Cover Inspection container 120 Liquid tank

Claims (4)

A leak inspection device configured by connecting a chamber for enclosing a container to be inspected, an air supply unit for supplying air to the chamber, a flow meter for measuring a flow rate of air flowing out of the chamber, and a tube. hand,
The chamber has a lid having an air supply port and a cylinder having an air outlet, and has a structure in which a space inside the chamber is formed by closing the lid to the cylinder. The inside space of the chamber is separated into a space connected to the air supply port and a space connected to the air exhaust port by the side and bottom surfaces of the container to be inspected by putting the container to be inspected and closing and sealing the lid. It has a possible structure,
A leak inspection apparatus for inspecting whether or not the inspected container is leaked by detecting whether or not the flow meter detects a flow of air when the container to be inspected is sealed in the chamber and air is supplied from the air supply unit. 2. The leak inspection apparatus according to claim 1, wherein a relationship between a pinhole diameter which causes a leak and a flow rate of the leaked air is grasped in advance, and the inspection is performed based on the reading of the flowmeter. A leak inspection device characterized in that the pinhole diameter of a container can be estimated. A chamber with a structure that consists of a lid with an air supply port and a cylinder with an air outlet, and forms an internal space by closing the lid with the cylinder. By closing and closing the lid, the chamber internal space has a structure that can be separated into a space connected to the air supply port and a space connected to the air discharge port by the side and bottom surfaces of the container to be inspected. Using a chamber, when the container to be inspected is sealed in the chamber and air is supplied from the air supply port, the flow rate of the air leaking from the air outlet is measured by a flow meter, whereby the leakage of the container to be inspected is measured. A leak inspection method that checks for the presence or absence. 4. The leak inspection method according to claim 3, wherein a relationship between a pinhole diameter causing a leak and a flow rate of the leaked air at a constant air supply pressure is grasped in advance. A leak inspection method characterized in that if the leak flow rate based on the reading of the flow meter is equal to or less than the reference flow rate, it is determined to be good.

Images