JP3704053B2 - In-pipe film defect inspection apparatus and in-pipe film defect inspection method - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an in-tube coating defect inspection apparatus and an in-tube coating for inspecting a coating defect in a tube such as an expansion tube (bellows tube) formed by depositing an insulating coating inside a conductive tube, for example. The present invention relates to a defect inspection method.
[0002]
[Prior art]
Products made by coating an insulating film such as a fluororesin film on the inner peripheral side of a tube or tubular container made of metal or other conductive materials are semiconductors, environmental facilities, living facilities, food management It has been actively used in a wide range of fields such as medical equipment.
[0003]
In such a product, if a coating failure such as a pinhole defect occurs for some reason in the coated insulating film, the insulation and completeness of coverage are impaired at that part, and the product This may cause a process defect or malfunction in a plant or apparatus in which is used. For this reason, it is very important to perform an inspection in order to find a coating defect such as a pinhole defect.
[0004]
As a technique for inspecting such a coating defect, for example, an enamellator method has been proposed. In this enamellator method, an electrolyte such as a sodium chloride aqueous solution is injected into a tube or tubular container to be inspected, and the negative electrode side electrode of the detection device is immersed therein, while the tube or tubular The positive electrode side electrode of the detection device is brought into contact with the metal or conductive material portion of the container, and a voltage of about several volts is applied between the positive electrode side electrode and the negative electrode side electrode over a predetermined time. When leakage current flows between the side electrode and the negative electrode side electrode through the electrolyte, pinhole defects are detected in the insulating film coated on the inner peripheral surface of the tube or tubular container by detecting it. It is determined that a coating defect such as Alternatively, if no leakage current flows at this time, it is determined that there is no coating failure in the insulating film to be inspected.
[0005]
In addition, in JP-A-63-44158, an electrode is brought into contact with the inner surface of a metal can through an electrolyte solution containing a surfactant, and the electrode and the metal are moved while moving the electrode. When a voltage is applied to the can body and a leakage current flows, the insulation film coated on the inner peripheral surface of the tube or tubular container has a coating defect such as a pinhole defect. Techniques have been proposed for determining that it has occurred.
[0006]
In addition, in JP-A-6-79441, as a method for inspecting a coating defect in a container whose inner surface is coated with a thermosetting resin film or a thermoplastic resin film, the inside of the container to be inspected is described. The conductive brush is relatively rotated while being in contact with it, and a DC high voltage of 800 to 1000 [V] is applied between the conductive brush and the container, and the value of the current flowing between them is measured. A technique for detecting a coating defect in a container to be inspected based on a current value has been proposed.
[0007]
Furthermore, in addition to that, in Japanese Patent Laid-Open No. 2000-46776, a conductive brush is placed inside a metal container to be inspected when detecting the coverage inside the metal container having an insulating film deposited inside. The conductive liquid having a specific resistance of 12 [MΩ · cm] or more and 16 [MΩ · cm] or less is supplied to the surface of the insulating film while being inserted into contact with the insulating film, and the metal container and the conductive brush are relatively The conductive liquid is finely divided by a conductive brush by rotating it, and a voltage of 5 [V] to 30 [V] is applied between the metal container and the conductive brush in this state. A technique has been proposed in which when a leakage current occurs, a coating defect in a metal container to be inspected is detected by detecting the leakage current.
[0008]
[Problems to be solved by the invention]
As described above, conventionally, as a technique for inspecting the insulation failure of the insulation film in the tube or tubular container to be inspected, an electrolyte is interposed between the inspection object and the electrode, resulting in the insulation failure of the insulation film. In such a case, a leakage current caused by the detection is generated to detect the occurrence of the coating failure, or the conductive brush is used as an electrode, and the conductive brush is moved while being in contact with the inspection target. A technology that detects the occurrence of a coating defect by generating a leakage current by direct contact between the conductive brush and a defective coating part such as a pinhole defect or contact through an electrolyte. Has been proposed.
[0009]
However, in the technique using electrolyte, there is a disadvantage that accurate inspection is difficult unless the electrolyte is surely distributed over the entire inner side surface of the tube or container, and the electrolyte solution is filled inside the tube or container. Alternatively, there is a disadvantage that the inspection process becomes complicated and the throughput is low. For example, the operation of coating and the operation of completely removing or washing the electrolyte solution after the inspection are necessary.
[0010]
In addition, as a tube or container to be inspected, for example, there is a tube-like complicated shape (this is also called an Ω structure) instead of a straight cylindrical shape such as an expansion tube (bellows tube). In the case of a tube or container of such a shape, there will be a part where the conductive brush is in strong contact and a part where it is not in contact, for example, if a small defect such as a pinhole defect has occurred in the deep part of the ridge For example, the defect may be overlooked without being detected.
[0011]
In addition, due to the contact between the conductive brush and the electrolyte, the surface of the tube or container to be inspected may be damaged or the material may be changed.
Because of such inconvenience, there has been a problem that it is substantially difficult to simply and reliably inspect the coating defect using the conventional inspection technique as described above.
[0012]
The present invention has been made in view of such problems, and its purpose is to easily detect electrolytes and coating defects that require complicated work and to damage the internal surface of the object to be inspected. Without using a conductive brush or the like, it is possible to easily and reliably detect a coating defect such as a pinhole defect in an insulating film (or non-conductive film) coated on the inner peripheral side surface of a tube or tubular container. An object of the present invention is to provide a tube defect inspection apparatus and tube defect inspection method that can be performed.
[0013]
[Means for Solving the Problems]
An in-pipe film defect inspection apparatus according to the present invention is an in-pipe film defect inspection apparatus for inspecting defects in an insulating or non-conductive film attached to the inner peripheral side surface of a conductive tube or a tubular container, While having a pointed uneven shape on the surface that concentrates the electric field, An electrode set in the tube or container so as to be inserted in the longitudinal direction of the tube or container while maintaining no contact with the coating, and a predetermined gap between the conductive tube or container and the electrode. A voltage applying means for applying a voltage between the conductive tube or container and the electrode when the voltage is applied by the voltage applying means in a state where the electrode is inserted into the tube or the container. And arc discharge detecting means for detecting the occurrence of arc discharge when arc discharge occurs.
[0014]
That is, in the in-pipe coating defect inspection apparatus according to the present invention, a voltage that causes an arc discharge unless a coating is interposed between a tube or container to be inspected and an electrode disposed in a non-contact manner with respect to the tube or container to be inspected. When an arc discharge is actually generated between the tube or container to be inspected and the electrode when applied, a coating such as a pinhole defect in the coating on the inner peripheral surface of the tube or container to be inspected The occurrence of a defect is detected.
[0015]
In addition, from the viewpoint of electrical material engineering, the above-mentioned insulation and non-conductivity are not necessarily clearly defined as distinction between insulation and non-conductivity. The characteristic of a substance or material, which is usually called a substance, is called insulation, and the characteristic of a substance or material that is not a good electrical conductor is considered to be non-conductive even if it has a low resistance, such as a specific resistance. Shall be called.
[0016]
Here, the electrode has a pointed uneven shape on the surface for concentrating the electric field. Is .
[0017]
In other words, by making the electrode surface shape into a pointed concavo-convex shape where the electric field concentrates, even if a low voltage is applied, an arc discharge is reliably generated between the coating defect and the electrode. Even coating defects such as hole defects are detected more reliably.
[0018]
Also, the electrode Screw A child mountain-shaped uneven shape Have It may be a thing.
[0019]
That is, by making the surface of the electrode into a thread-like uneven shape, the electric field concentrates at the tip of the thread, so even if a low voltage is applied, an arc discharge occurs between the coating defect and the electrode. Will surely occur, and even coating defects such as minute pinhole defects will be detected more reliably.
[0020]
The arc discharge detection means is based on a voltage change between the conductive tube or container and the electrode when an arc discharge is generated between the conductive tube or container and the electrode. The generation of the arc discharge may be detected.
[0021]
That is, when an arc discharge occurs between a conductive tube or container and the electrode, a change occurs in the voltage between the conductive tube or container and the electrode. Based on this, the occurrence of a coating failure such as a pinhole defect in the coating on the inner peripheral side surface of the tube or container to be inspected is detected.
[0022]
Alternatively, the arc discharge detection means may be configured to detect the arc based on a change in current flowing between the conductive tube or container and the electrode when an arc discharge occurs between the conductive tube or container and the electrode. It is good also as what detects generation of discharge.
[0023]
That is, when an arc discharge is generated between a conductive tube or container and the electrode, a change occurs in the current flowing between the conductive tube or container and the electrode. Based on the above, occurrence of a coating defect such as a pinhole defect in the coating on the inner peripheral side surface of the tube or container to be inspected is detected.
[0024]
An in-pipe film defect inspection method according to the present invention is an in-pipe film defect inspection method for inspecting a defect of an insulating or non-conductive film deposited on an inner peripheral side surface of a conductive tube or a tubular container, While keeping non-contact with the coating inside the tube or container The surface has an uneven shape that concentrates the electric field at the tip. An electrode is inserted in the longitudinal direction of the tube or container, a voltage is applied between the conductive tube or container and the electrode, and the voltage is inserted in the tube or container. When the voltage is applied by the applying means and an arc discharge occurs between the conductive tube or container and the electrode, the occurrence of the arc discharge is detected.
[0025]
In other words, when a voltage that causes arc discharge is applied between the tube or container to be inspected and the electrode disposed in non-contact with the tube, the inspection object is actually applied. When an arc discharge occurs between the tube or container and the electrode, it is possible to detect the occurrence of a coating defect such as a pinhole defect in the coating on the inner peripheral surface of the tube or container to be inspected.
[0026]
The other in-pipe film defect inspection method according to the present invention is an in-pipe film defect inspection method for inspecting a defect of an insulating or non-conductive film deposited on the inner peripheral surface of a conductive tube or a tubular container. In the tube or container, the electric field is concentrated on the tip while maintaining no contact with the coating. Concave An electrode having a convex shape on the surface is inserted in the longitudinal direction of the tube or container, an inert gas is introduced into the tube or container, the gas pressure is reduced, and the electrode is connected to the tube or container. In a state of being inserted inside, when a voltage is applied between the conductive tube or container and the electrode, and an arc discharge occurs between the conductive tube or container and the electrode due to the application of the voltage, The generation of the arc discharge is detected.
[0027]
In other words, an inert gas is introduced between the tube or container to be inspected and the electrode arranged in a non-contact manner with respect to the tube, and the gas pressure is reduced to make it easier for arc discharge to occur. In addition, when a voltage that causes an arc discharge if a coating is not present is applied, an arc discharge actually occurs between the tube or container to be inspected and the electrode, and based on that, an inspection target is generated. The occurrence of coating defects such as pinhole defects can be detected in the coating on the inner peripheral surface of the tube or the container.
[0028]
Here, argon gas is used as the inert gas, a voltage of 1 [kV] or more is applied as the voltage, and the gas pressure of the argon gas is applied when a defect exists in the film. The pressure may be reduced to a pressure in the range of 2600 [Pa] to 4000 [Pa] where the arc discharge may occur.
[0029]
That is, an argon gas that can be easily handled as an inert gas and is suitable for arc discharge is used, and the gas pressure of the argon gas is 2600 [Pa] to 4000 [corresponding to the arc discharge characteristics of the argon gas. By reducing the pressure to a pressure within the range of Pa], when a coating defect such as a pinhole defect has occurred in the coating on the inner peripheral side surface of the tube to be inspected or the container, it is more reliably detected. Will be able to.
[0030]
Also, as the electrode Screw A child mountain-shaped uneven shape Have You may make it use a thing.
[0031]
In other words, the surface of the electrode is formed into a thread-like uneven shape, so that an electric arc is concentrated on the tip of the thread and the arc discharge is generated between the coating defect and the electrode even when a low voltage is applied. Can be reliably generated, and even a coating defect such as a minute pinhole defect can be detected more reliably.
[0032]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
[0033]
FIG. 1 shows a schematic configuration of an in-pipe film defect inspection apparatus according to an embodiment of the present invention. This in-pipe coating defect inspection apparatus is an in-pipe for inspecting defective coating or film defects of a coating 1 in a conductive metal tube (or tubular container) 2 having an insulating coating 1 deposited on its inner peripheral side surface. An apparatus for inspecting a film defect, wherein the electrode 3 is set so as to be able to pass through the inside of the metal tube 2 to be inspected while maintaining no contact with the film 1, and between the metal tube 2 and the electrode 3 to be inspected. A voltage is applied in a state where a predetermined voltage is applied to the high voltage generation circuit (voltage applying means) 11 and the electrode 3 is inserted into the metal tube 2, and an arc is generated between the metal tube 2 and the electrode 3. When the discharge 20 is generated, a voltage measuring device (arc discharge detecting means) 12 that detects the generation of the arc discharge 20 is provided as a main part thereof.
[0034]
Furthermore, a gas cylinder 13 for introducing an inert gas (rare gas) such as Ar (argon) gas into the inside of the metal tube 2 and an arc discharge by reducing the pressure of the inert gas introduced into the inside of the metal tube 2. And a vacuum pump device 14 that is in a low pressure state in which 20 is easily generated.
[0035]
More specifically, the metal pipe 2 to be inspected has, for example, a length of 20 to 30 [cm] and an inner diameter of about 10 [cm], and an insulating material such as a fluororesin is provided on the inner peripheral side surface thereof. The coating 1 is coated (attached) so as to have a uniform film thickness as much as possible.
[0036]
An electrode 3 is inserted into the metal pipe 2 to be inspected while being in non-contact with the coating 1 in substantially parallel to the longitudinal direction of the metal pipe 2. The electrode 3 has a thread-like (screw-like spiral) asperity formed on the surface of a substantially rod-like outer shape, and the apex portion 31 of the ridge line of the convex part like the screw thread has an acute shape. Therefore, the electric field concentrates on the tip 31 (the electric field strength becomes high), and a discharge phenomenon such as arc discharge 20 is likely to occur.
[0037]
Lids 4 and 5 are temporarily attached to both ends of the metal tube 2 only during the inspection process. The lids 4 and 5 seal the inside of the metal tube 2 and increase the airtightness. One lid 4 holds the electrode 3 at the approximate center thereof. The other lid 5 is provided with a duct 7 connected to the vacuum pump device 14 via the opening / closing valve 6 and a duct 9 connected to the gas cylinder 13 via the opening / closing valve 8.
[0038]
With the lids 4 and 5 attached, Ar gas is introduced from the gas cylinder 13 into the sealed interior of the metal tube 2, and the gas pressure is reduced by the vacuum pump device 14.
[0039]
One output terminal 111 of the high voltage generation circuit 11 is connected to the outer peripheral side surface of the metal tube 2, which is a conductive tube, via a wiring 112, and the other output terminal 113 of the high voltage generation circuit 11 is connected to the wiring 114. To the electrode 3. Therefore, the AC high voltage output from the high voltage generation circuit 11 is applied between the metal tube 2 and the electrode 3.
[0040]
A voltage measuring instrument 12 is connected to both output terminals 111 and 113 of the high voltage generating circuit 11 so that a voltage change can be detected when an arc discharge 20 is generated between the metal tube 2 and the electrode 3. .
[0041]
Here, a more specific circuit configuration of the high voltage generation circuit 11 is preferably as shown in FIG. 2, for example. That is, the output voltage is boosted by the transformer 121, and the voltage output from the output terminals 111 and 113 can be adjusted to a high voltage of an arbitrary value up to several [kV] by the variable inductance 122. Therefore, the AC high voltage applied between the metal tube 2 and the electrode 3 can be adjusted to an arbitrary voltage value. The voltage measuring device 12 is connected to both the output terminals 111 and 113, and the voltage between the two output terminals 111 and 113, that is, the voltage between the metal tube 2 and the electrode 3 is measured by the voltage measuring device 12. Is done.
[0042]
When a coating defect such as a pinhole defect 21 has occurred in the coating 1, an arc discharge 20 occurs between the electrode 3 and the defective coating portion (pinhole defect 21 in FIG. 1) of the metal tube 2. . The voltage measuring device 12 measures a voltage change when the arc discharge 20 is generated. Generation | occurrence | production of the arc discharge 20 is detected based on the voltage change measured in this way.
[0043]
Next, the in-pipe film defect inspection method according to the present embodiment will be described.
[0044]
First, the electrode 3 is inserted into the metal pipe 2 to be inspected while being in non-contact with the coating 1 in substantially parallel to the longitudinal direction of the metal pipe 2. Then, lids 4 and 5 are temporarily attached to both ends of the metal tube 2, respectively. The inside of the metal tube 2 is sealed by the lids 4 and 5 so that the airtightness is high. One lid 4 holds the electrode 3 at substantially the center, and the other lid 5 is provided with it. The air inside the metal pipe 2 is gradually decompressed (removed and thinned) by the vacuum pump device 14 through the ducts 7 and 9, while Ar gas (not shown) is supplied from the gas cylinder 13. When the pressure is introduced into the inside of the metal tube 2 and the pressure becomes a pressure within a range of 2600 [Pa] to 4000 [Pa] (about 20 [Torr] to about 30 [Torr]), The on-off valves 6 and 8 provided in the respective ducts 7 and 9 are closed, and the operation of the vacuum pump device 14 is also stopped. In this manner, the air inside the metal tube 2 is replaced with Ar gas in a state where the pressure is reduced and the arc discharge 20 is likely to occur.
[0045]
In this state, the high voltage generation circuit 11 is operated, the variable inductance 122 is adjusted, and the voltage value output from the high voltage generation circuit 11 is gradually increased, so that the voltage between the metal tube 2 and the electrode 3 is increased. An alternating high voltage of up to several [kV] is applied.
[0046]
When the voltage value is increased in this way, if there is a coating failure such as the pinhole defect 21 on the inner peripheral side surface of the metal tube 2, the portion of the coating failure such as the pinhole defect 21 is present. Arc discharge 20 is generated between the metal tube 2 and the electrode 3, resulting in a voltage drop between the output terminals 111 and 113 of the high voltage generation circuit 11. Therefore, by measuring a voltage drop peculiar to the occurrence of the arc discharge 20 with the voltage measuring instrument 12, the occurrence of the arc discharge 20 can be detected, and the presence of a coating defect is detected based on the measurement. be able to.
[0047]
Alternatively, when no coating failure occurs on the inner peripheral side surface of the metal tube 2 and sufficient coverage of the coating 1 is achieved, the metal tube 2 and the electrode can be used even if the voltage value is increased. No arc discharge 20 is generated between the two. Therefore, in such a case, since the voltage drop caused by the arc discharge 20 is not measured by the voltage measuring instrument 12, in such a state until the end of the predetermined measurement, no coating failure has occurred. Can be determined.
[0048]
In addition, using the in-pipe film defect inspection apparatus according to the present embodiment, as shown in FIG. 3, the wall surface is a bellows-like (tub-like) expansion tube made of a conductive material such as metal. It is also possible to inspect the coverage of the coating 1 on the inner peripheral side surface of the metal tube 23. In FIG. 3, the same parts as those in FIG. 1 are denoted by the same reference numerals.
[0049]
In other words, in the conventionally proposed inspection apparatus and inspection method techniques, particularly when a pinhole defect or the like is generated in the back of the corrugation of the wall surface of such a bellows-like expansion and contraction tube. It was extremely difficult to reliably detect pinhole defects.
[0050]
However, according to the in-pipe film defect inspection apparatus and the inspection method using the same according to the present embodiment, the metal tube 23, which is such a bellows-like expansion and contraction tube, is located behind the unevenness of the wall surface. Even when a pinhole defect 24 is generated in the coated film 1, it can be reliably detected.
[0051]
[Example]
Using the above-described tube coating defect inspection apparatus, the coating defects were actually inspected on the inner circumferential side of the metal tube 2 in which the coating 1 made of fluororesin was deposited on the inner circumferential side as described above. .
[0052]
As a result, when pinhole defects having a diameter of about 0.1 [mm] exist in the coating 1, the Ar gas is reduced to 400 [Pa] (about 3 [Torr]) to reduce the inside of the metal tube 2 With the high voltage generating circuit 11, an AC high voltage of 3 [kV] was applied (multiplied) between the electrode 3 and the metal tube 2 by the high voltage generating circuit 11, and an arc discharge 20 was generated, resulting in a clear voltage change. Was confirmed to be detected. Further, in the case of the metal tube 2 in which the coating failure of the coating 1 such as the pinhole defect 21 does not occur at all, 3 [kV] or more between the electrode 3 and the metal tube 2 under the same conditions as described above. Even when an AC high voltage of 1 is applied, no arc discharge 20 was generated, and therefore no voltage change was detected.
[0053]
In this way, by detecting a voltage change that occurs when the arc discharge 20 occurs, it is possible to reliably and easily inspect whether or not there is a deposition failure in the coating 1 inside the metal tube 2.
[0054]
Needless to say, the concavo-convex shape of the surface of the electrode 3 is not limited to the screw thread shape as described above. In addition to this, each uneven shape is not continuous like a screw thread. For example, as shown in FIG. 4, for example, each uneven shape 38 is an independent disk shape or abacus bead. The shape may be as follows. Alternatively, for example, the ridge line of the concavo-convex shape of the tip portion extends in the longitudinal direction of the rod-shaped electrode 3 (shape like a pinion gear), or the fin-shaped ruggedness protrudes radially around the rod-shaped electrode 3. It is also possible to make it a shape (all are not shown). However, the shape shown in FIG. 1 is more desirable from the viewpoint of line symmetry or longitudinal uniformity of the shape centered on the rod-shaped electrode 3.
[0055]
Needless to say, the material of the tube or container to be inspected is not limited to the above. It is also possible to inspect pipes and containers made of non-metallic conductive materials.
[0056]
【The invention's effect】
As explained above, claims 1 to 4 The in-pipe coating defect inspection device according to any one of claims 1 to 3, or a claim 5 Or 8 According to the in-tube coating defect inspection method described in any one of the above, if no coating is interposed between the tube or container to be inspected and the electrode arranged in a non-contact manner, an arc discharge is generated. If an arc discharge is actually generated between the tube or container to be inspected and the electrode when an appropriate voltage is applied, the film on the inner peripheral surface of the tube or container to be inspected is Since the occurrence of such coating defects is detected, it is difficult to detect electrolytes that require complicated work, and it is easy to detect coating defects, and there is a risk of damaging the internal surface of the inspection target. Even without using a brush or the like, it is possible to easily and reliably detect a coating defect such as a pinhole defect in an insulating film or a non-conductive film coated on the inner peripheral surface of a tube or tubular container. An effect.
[0057]
In addition, since it is not necessary to use an electrolyte solution, it is possible to use a lot of troublesome work such as removing or washing the electrolyte solution after the end of the inspection process, and the throughput of the inspection process is good. It can be.
[0058]
In addition, since non-contact inspection can be performed without using a conductive brush, electrolyte, etc., it eliminates damage to the inside of the tube and container (inner peripheral side, etc.) and changes in material. Can do.
[0059]
Furthermore, By making the shape of the surface of the above electrode into a concavo-convex shape having a pointed shape in which the electric field concentrates, it is possible to reliably generate an arc discharge between the coating defect and the electrode even if a low voltage is applied. Thus, even a coating failure such as a minute pinhole defect can be detected more reliably.
[0060]
In particular, the claims 2 In-pipe coating defect inspection device or claim 8 According to the in-tube coating defect inspection method described above, the surface shape of the above electrode is formed into a thread-like concavo-convex shape, and an electric field is concentrated on the tip of the concavo-convex shape, so that only a low voltage is applied. Thus, it is possible to reliably generate an arc discharge between the coating defect and the electrode, and even a coating defect such as a minute pinhole defect can be detected more reliably.
[0061]
In particular, the claims 6 According to the method for inspecting a coating film defect described in the tube, a coating defect such as a pinhole defect is formed on the coating on the inner peripheral side surface of the tube or container to be inspected by using an inert gas reduced in pressure as an atmosphere causing arc discharge. Since arc discharge has occurred more reliably when it has occurred, the occurrence of coating failure can be detected more reliably.
[0062]
And further claims 7 According to the in-pipe film defect inspection method described, argon gas suitable for arc discharge is used as the inert gas, and the gas pressure is 2600 [Pa] corresponding to the arc discharge characteristics. ] To 4000 [Pa], and if a coating failure such as a pinhole defect has occurred in the coating on the inner peripheral surface of the tube or container to be inspected, the arc discharge is more reliable. Therefore, it is possible to more reliably detect the occurrence of a coating defect.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic configuration of an in-pipe film defect inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a specific circuit configuration of a high voltage generation circuit.
FIG. 3 shows an expansion tube and an in-tube coating in the case where the coverage of the coating on the inner peripheral surface of the bellows-like expansion tube is inspected by the in-tube coating defect inspection apparatus according to the embodiment of the present invention. It is a figure showing the whole general | schematic structure including a defect inspection apparatus.
FIG. 4 is a diagram showing an example of variations in the uneven shape on the surface of an electrode.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Coating, 2 ... Metal pipe, 3 ... Electrode, 4, 5 ... Lid, 6, 8 ... Open / close valve, 7, 9 ... Duct, 11 ... High voltage generation circuit, 12 ... Voltage measuring instrument, 13 ... Gas cylinder, 14 ... Vacuum pump device, 20 ... Arc discharge

Claims (8)

An in-pipe film defect inspection apparatus for inspecting a defect of an insulating or non-conductive film deposited on an inner peripheral side surface of a conductive tube or a tubular container,
Provided on the surface with a pointed concavo-convex shape for concentrating the electric field, and inside the tube or container, an electrode set so as to be able to be inserted in the longitudinal direction of the tube or container while keeping non-contact with the coating;
Voltage applying means for applying a predetermined voltage between the conductive tube or container and the electrode;
When the voltage is applied by the voltage applying means in a state where the electrode is inserted into the tube or container and an arc discharge occurs between the conductive tube or container and the electrode, An in-pipe film defect inspection device comprising: an arc discharge detection means for detecting occurrence of arc discharge. The electrodes, pipe coating defect inspection apparatus according to claim 1, characterized in that it comprises a threaded element mountain-like irregularities. The arc discharge detecting means is configured to detect the arc discharge based on a voltage change between the conductive tube or container and the electrode when an arc discharge occurs between the conductive tube or container and the electrode. The in-pipe film defect inspection apparatus according to claim 1, wherein the occurrence of sag is detected. The arc discharge detection means detects the arc discharge based on a change in current flowing through the conductive tube or container and the electrode when an arc discharge occurs between the conductive tube or container and the electrode. The tube defect inspection apparatus according to claim 1, wherein occurrence is detected. An in-pipe film defect inspection method for inspecting defects in an insulating or non-conductive film deposited on the inner peripheral side surface of a conductive tube or tubular container,
Inside the tube or container, while maintaining non-contact with the coating, an electrode having an uneven shape that concentrates the electric field on the tip is inserted in the longitudinal direction of the tube or container,
Applying a voltage between the conductive tube or vessel and the electrode;
When the voltage is applied by the voltage applying means and an arc discharge is generated between the conductive tube or container and the electrode while the electrode is inserted into the tube or container, the arc discharge is generated. An in-tube defect inspection method characterized by detecting the occurrence of water. An in-pipe film defect inspection method for inspecting defects in an insulating or non-conductive film deposited on the inner peripheral side surface of a conductive tube or tubular container,
Inside the tube or container, while maintaining non-contact with the coating, an electrode having an uneven shape that concentrates the electric field on the tip is inserted in the longitudinal direction of the tube or container,
Introducing an inert gas into the tube or container, reducing the gas pressure,
With the electrode inserted into the tube or container, a voltage is applied between the conductive tube or container and the electrode, and by applying the voltage, the conductive tube or container and the electrode A method for inspecting a coating film defect in a pipe, characterized by detecting the occurrence of arc discharge when arc discharge occurs between them. Argon gas is used as the inert gas,
A voltage of 1 [kV] or more is applied as the voltage,
The gas pressure of the argon gas is reduced to a pressure in the range of 2600 [Pa] or more and 4000 [Pa] or less in which the arc discharge can be generated by applying the voltage when a defect is present in the film. The in-pipe film defect inspection method according to claim 6 . As the electrode, pipe coating defect inspection method according to one of claim any one of claims 5 to 7, characterized by using a material having a screw element mountain-like irregularities.

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