JP4669407B2 - Defect inspection equipment for porous hollow fiber membranes - Google Patents

Description

  The present invention relates to a defect inspection apparatus for a porous hollow fiber membrane.

  The porous hollow fiber membrane is generally processed into a bundled assembly as a filter unit, and is used in many applications such as artificial organs, wastewater treatment, and gas separation. If the porous hollow fiber membrane constituting the filter unit has defects such as cracks, tears, and small holes (pinholes) penetrating the membrane, the stock solution is directly mixed into the permeate through the defects. As a result, the permeated liquid contains a lot of substances to be removed. For this reason, filter units used for medical applications that require strict selective permeability are required to have no defect in the porous hollow fiber membrane. For this reason, the filter unit is inspected for defects after processing, and those found are repaired or disposed of.

  In order to improve the processing yield of the filter unit, it is necessary to use a porous hollow fiber membrane having no defects. Therefore, if the entire number of the porous hollow fiber membranes are inspected nondestructively and the portion where the defect is detected is removed, a porous hollow fiber membrane having substantially no defect can be obtained. Therefore, techniques for continuously detecting defects in the porous hollow fiber membrane while running the porous hollow fiber membrane have been proposed (for example, Patent Documents 1 and 2).

  According to the technique disclosed in Patent Document 1, a porous hollow fiber membrane having a hollow portion filled with a liquid is passed through a pressurized gas. At that time, if there is a pinhole in the porous hollow fiber membrane, gas is injected into the hollow portion of the porous hollow fiber membrane through the pinhole, and bubbles are generated in the hollow portion. Therefore, pinholes are detected by detecting bubbles in the hollow portion. In this way, a defective portion such as a pinhole is replaced with a bubble injected into the hollow portion and detected indirectly.

  Moreover, according to the technique disclosed in Patent Document 2, the porous hollow fiber membrane is passed through the pressurized liquid. At that time, if the porous hollow fiber membrane has a pinhole, the liquid is injected into the hollow portion of the porous hollow fiber membrane through the pinhole. Therefore, pinholes are detected by detecting the liquid in the hollow portion. In this manner, the defective portion such as a pinhole is replaced with the liquid injected into the hollow portion and detected indirectly.

JP 56-22922 JP 58-129230 A

  However, in the technique disclosed in Patent Document 1, it is necessary to inject a liquid into the hollow portion of the porous hollow fiber membrane in advance. It also needs to be injected so that bubbles do not get mixed with the liquid. Furthermore, after the defect inspection, it is necessary to remove the liquid filled in the hollow portion of the porous hollow fiber membrane.

  Moreover, in the technique disclosed in Patent Document 2, if the porous hollow fiber membrane has high hydrophilicity, the liquid penetrates into the hollow part while passing through the pressurized liquid, even if there is no defect. There is a fear.

  Accordingly, an object of the present invention is to provide a defect detection apparatus capable of continuously and easily detecting defects in a traveling porous hollow fiber membrane for both hydrophobic and hydrophilic porous hollow fiber membranes. There is.

According to the present invention,
A defect inspection device for a porous hollow fiber membrane,
A container constituting an internal space in which a liquid tank containing liquid is disposed ;
And decompression means for decompressing the internal space,
The porous hollow fiber membrane is continuously introduced so as to be introduced into the internal space from the outside of the container , passed through the liquid under reduced pressure stored in the liquid tank, and led out from the internal space of the container to the outside. Continuous dipping means for conveying to,
A bubble detection means for detecting bubbles sucked into the liquid from a defective portion of the porous hollow fiber membrane passing through the liquid;
Liquid supply means for supplying the liquid to the liquid tank, so that the liquid in the liquid tank maintains a liquid level with a certain height.
A defect inspection apparatus for a porous hollow fiber membrane is provided.

  According to the defect detection device for a porous hollow fiber membrane of the present invention configured as described above, the porous hollow fiber membrane is passed through a liquid under reduced pressure. At that time, if the porous hollow fiber membrane has a defect such as a pinhole, the gas in the hollow portion of the porous hollow fiber membrane is sucked into the liquid outside the porous hollow fiber membrane through the defect. And a defect can be indirectly detected by detecting the bubble sucked out from the porous hollow fiber membrane.

  Furthermore, in the present invention, since the porous hollow fiber membrane is continuously passed through the liquid, it is possible to easily detect defects continuously in the manufacturing process of the porous hollow fiber membrane without cutting the porous hollow fiber membrane. You can also Moreover, in this invention, it is not necessary to fill the hollow part of a porous hollow fiber membrane with the liquid for a test | inspection, Therefore, the process of removing the liquid with which the hollow part was filled after a test | inspection is also unnecessary.

  Further, in the present invention, since air bubbles sucked out of the porous hollow fiber membrane are detected in the liquid under reduced pressure, there is no fear of erroneous detection due to the liquid soaking into the porous hollow fiber membrane. For this reason, defect detection can be performed regardless of the hydrophobicity and hydrophilicity of the porous hollow fiber membrane. Therefore, according to the defect inspection apparatus for the porous hollow fiber membrane of the present invention, the defect of the traveling porous hollow fiber membrane can be easily and continuously detected for both the hydrophobic and hydrophilic porous hollow fiber membranes. can do.

Furthermore , the liquid level of the liquid can be easily kept constant, and the liquid depth of the porous hollow fiber membrane passing through the liquid can be kept constant. As a result, fluctuations in pressure applied to the porous hollow fiber membrane passing through the liquid can be suppressed and made constant, and the defect detection accuracy of the porous hollow fiber membrane can be made constant.

  And the larger the degree of decompression of the internal space, in other words, the lower the pressure of the liquid applied to the porous hollow fiber membrane, the smaller the defect of the porous hollow fiber membrane can be detected. Therefore, by keeping the liquid level constant, the size of the minimum defect that can be detected can be made constant.

According to another preferred embodiment of the present invention, the liquid supply means comprise a supply-off valve for switching the open and closed states of the supply port, and a supply control valve to adjust the supply amount of liquid to the liquid tank Tei The
The degree of decompression of the internal space of the container can be controlled by controlling the amount of liquid supplied by the supply on / off valve and the supply control valve and by controlling the exhaust and liquid discharge by the pump.

According to another preferred embodiment of the present invention, the liquid supply means comprises a filtering device for performing filtering of the liquid, and a, a deaerator for removing air bubbles in the liquid,
If the liquid was filtered by the filtration device and the bubbles were removed by the degassing device, the suspended matter and bubbles in the liquid supplied to the first liquid tank were sucked out from the defective portion of the porous hollow fiber membrane. It is possible to prevent detection by mistake with bubbles. Thereby, the reliability of defect detection can be improved.

According to another preferred aspect of the present invention, the apparatus further comprises jet means for jetting the liquid supplied from the liquid supply means along the wall surface of the liquid tank facing the bubble detection means.
Thereby, it is possible to prevent bubbles in the liquid from adhering to the side surface of the container. As a result, it is possible to prevent erroneous detection of air bubbles adhering to the side surface of the container as air bubbles sucked out from the porous hollow fiber membrane. Thereby, the reliability of defect detection can be improved.

According to another preferred aspect of the present invention, the container has an inlet through which the porous hollow fiber membrane introduced into the internal space passes, and a guide through which the porous hollow fiber led out from the internal space passes. An outlet is provided, and each of the inlet and the outlet has a non-contact type seal structure.
Thereby, the porous hollow fiber membrane can be continuously introduced into the container and continuously led out from the container while ensuring the hermeticity of the container and maintaining the decompressed state of the internal space of the container.

In the present invention, preferably, the seal structure is sealed at a seal flow rate of a critical flow rate.
As a result, gaps are provided between the inlet and outlet and the porous hollow fiber membrane so that the inlet and outlet are in contact with the porous hollow fiber membrane and do not damage the porous hollow fiber membrane. However, suitable sealing properties can be maintained.

In the present invention, the seal structure is preferably a labyrinth seal.
As a result, gaps are provided between the inlet and outlet and the porous hollow fiber membrane so that the inlet and outlet are in contact with the porous hollow fiber membrane and do not damage the porous hollow fiber membrane. However, suitable sealing properties can be maintained.

Further, in the present invention, preferably, according to the yarn diameter detection means for detecting the thickness of the porous hollow fiber membrane introduced into the container, and the thickness of the porous hollow fiber membrane detected by the yarn diameter detection means And an automatic opening / closing mechanism for adjusting the opening diameter of each of the inlet and outlet.
The porous hollow fiber membrane may have a portion with a large diameter, such as a portion where the porous hollow fiber membranes are joined together. Then, when the diameter of the yarn is detected and the diameter of the inlet and outlet is temporarily increased when such a connecting portion passes through the inlet and outlet, the portion with the larger diameter is caught on the seal structure. Can be avoided. Thereby, smoother continuous detection can be performed.

In the present invention, preferably, the continuous dipping means allows the porous hollow fiber membrane to pass through the liquid contained in the internal space of the container at a certain depth from the liquid surface.
Thereby, the liquid depth of the porous hollow fiber membrane that passes through the liquid can be kept constant. As a result, fluctuations in pressure applied to the porous hollow fiber membrane passing through the liquid can be suppressed and made constant, and the defect detection accuracy of the porous hollow fiber membrane can be made constant.

In the present invention, it is preferable that the bubble detecting means is composed of a light projecting unit and a light receiving unit arranged to face each other.
As a result, the amount of light reaching the light receiving unit from the light projecting unit is reduced due to refraction, scattering, or the like by the bubble, so that the bubble can be detected.

In the present invention, it is preferable that the bubble detection means includes a light projecting unit and a light receiving unit arranged such that their optical axes substantially intersect with each other above the passage position of the porous hollow fiber membrane in the liquid. It consists of.
With this arrangement, when there is no bubble, the light emitted from the light projecting unit does not reach the light receiving unit, but when there is a bubble, the light emitted from the light projecting unit is scattered by the bubble, Scattered light reaches the light receiving part. Therefore, bubbles can be detected by receiving the scattered light.

In the present invention, preferably, a signal processing device for differentiating the output signal of the bubble detection means is provided.
As a result, the rate of change in decrease or increase in the amount of received light in the light receiving unit due to the detection of bubbles can be detected, and bubbles can be detected based on this rate of change.

According to another preferred embodiment of the present invention, the continuous immersion means, a plurality of porous hollow fiber membrane, passed through the liquid, the container, the interior space, from different porous hollow fiber membrane Ru Tei comprising a separator for separating the respective aspirated air bubbles each other.
Thereby, the sucked out bubbles can be easily distinguished and detected for each porous hollow fiber membrane.

  According to the porous hollow fiber membrane inspection device of the present invention, it is possible to easily and continuously detect defects in the traveling porous hollow fiber membrane for both hydrophobic and hydrophilic porous hollow fiber membranes. it can.

  Hereinafter, an embodiment of a defect inspection apparatus for a porous hollow fiber membrane of the present invention (hereinafter also simply referred to as “defect inspection apparatus”) will be described with reference to the accompanying drawings. FIG. 1 is a schematic front view of the defect inspection apparatus according to the embodiment. FIG. 2 is a schematic side view of the defect inspection apparatus according to the embodiment. 2 is a schematic cross-sectional view taken along line II-II in FIG.

  As shown in FIG. 1, the defect inspection apparatus of the present embodiment includes a container 1 that constitutes an internal space that contains a liquid, a pump 2 that serves as a decompression unit for reducing the internal space of the container 1 from atmospheric pressure, The porous hollow fiber membrane M is continuously introduced from the outside of the container 1 into the internal space, passed through the liquid L accommodated in the internal space of the container 1, and led out from the internal space of the container 1 to the outside. The continuous dipping means 3 that guides in this way, and the bubble detection means 11 that detects the bubbles B sucked into the liquid L from the defective portion of the porous hollow fiber membrane M passing through the liquid L are provided. Hereinafter, each component will be described.

  In the present embodiment, the container 1 includes a liquid tank 4 that contains a liquid and a flange portion 5 that is disposed so as to cover the upper part of the liquid tank 4 in order to configure a decompressed internal space. . The space between the upper edge of the outer periphery of the liquid tank 4 and the flange portion 5 is sealed with a seal portion 6. The seal part 6 is formed by, for example, an O-ring. Then, in order to decompress the internal space of the container 1, the air is exhausted by the pump 2 from the exhaust port 53 provided in the flange portion 5.

  In addition, there is no restriction | limiting in particular in the material of the flange part 5, For example, resin, such as polyester, polyvinyl chloride, polyethylene, polyamide, a polypropylene, a polyacetal, metals, such as iron, aluminum, copper, stainless steel, nickel, titanium, or alloys Or these composite materials etc. can be used.

  The material of the seal portion 6 is not particularly limited as long as the gap between the liquid tank 4 and the flange portion 5 can be sealed. For example, polyurethane rubber, silicone rubber, polybutadiene rubber, ethylene propylene rubber, polypropylene rubber, Rubber such as chloroprene rubber, nitrile rubber, styrene butadiene rubber, butyl rubber, fluorinated hydrocarbon rubber, polyester, polyvinyl chloride, polyethylene, polyamide, polypropylene, polyacetal resin, iron, aluminum, copper, stainless steel, nickel, titanium Such metals, alloys, or composite materials thereof can be used. Further, rubbers such as rubbers generally used are preferable.

  In this embodiment, water is used as the liquid L. When a defect detection device is incorporated in the production line of the porous hollow fiber membrane and the defect is continuously detected while producing the porous hollow fiber membrane, the liquid used for cleaning the porous hollow fiber membrane (for example, It is desirable to use the same liquid L as the pure water. Moreover, since the magnitude | size of the defect which can be detected is influenced by the magnitude | size of the surface tension of the liquid L, the liquid whose surface tension characteristic is known correctly like water is preferable. For example, the surface tension of water at 28 ° C. is about 73.0 mN / m.

  In addition, the liquid accommodated in the internal space of the container 1 is not limited to water. For example, methanol, ethanol, formamide used as a wet tension test reagent, or a mixture of these and water may be used. . For example, the surface tension of the liquid can be adjusted by adjusting the temperature and the mixing ratio of water and methanol.

  In addition, as the degree of vacuum (vacuum) in the internal space of the container 1 is higher and the surface tension of the liquid L is smaller, bubbles are sucked out from smaller defects of the porous hollow fiber membrane. Therefore, the size of the smallest defect that can be detected can be selected by adjusting the degree of vacuum in the container and the surface tension of the liquid.

  In the present embodiment, a part of the liquid tank 4 of the container 1 is partitioned by a partition plate 40, the inside of this partition is a first liquid tank 4a, and the outside is a second liquid tank 4b. Here, the dimensions of the container 4 are, for example, a height of about 120 mm, a length of about 410 mm, and a depth of about 110 mm. The depth direction of the container 4 is not partitioned, and only the length direction is partitioned by the partition plate 40.

  And the liquid from the tank (not shown) of a liquid supply source is supplied from the supply port 41 to the 1st liquid tank 4a. The liquid tank 4 of the container 1 overflows the liquid L and maintains a constant liquid level. Thereby, the height of the liquid level of the first liquid tank 4a is always kept constant, and the porous hollow fiber membrane M can always run at a constant depth in the liquid. Further, the liquid L overflowing from the first liquid tank 4a is received by the second liquid tank 4b, and is sucked and discharged from the discharge port 42 of the second liquid tank 4b by the water ring vacuum pump 2.

  The liquid tank 4 and the partition plate 40 may be formed of a material such as transparent glass or plastic, or may be formed of an opaque material. However, in the case where the side wall of the liquid tank 4 is formed of an opaque material, when using an optical bubble detection means as will be described later, a viewing window made of transparent glass or the like is provided at a portion facing the bubble detection means. Good.

  Further, when a photoelectric sensor or an image processing device is used as the bubble detection means, only the portion of the side wall of the container 4 that is observed in the liquid L by the detection means 11 is formed of transparent glass or plastic, It is advisable to shield the parts other than the observation. If comprised in this way, disturbance light can be excluded and the detection accuracy of the bubble B can be improved.

  On the liquid supply path from the liquid supply source tank to the supply port 41 of the first liquid tank 4a, a supply on / off valve 15 for switching the open / close state of the liquid supply port 41, and a liquid supply amount are adjusted. A supply control valve 16 is provided. By these on-off valves 15 and 16, the supply amount and supply frequency of the liquid L into the container 1 are adjusted.

  Further, a filtration device 9 that performs liquid filtration and a deaeration device 10 that removes bubbles in the liquid are provided on this path. Thereby, the foreign material is removed and the degassed liquid is supplied to the first liquid tank 4a.

  Moreover, the container 1 is provided with the jet means 14 which jets a liquid along the wall surface which faced the bubble detection means. In this embodiment, the plate 14 is provided as jet means. The liquid L supplied from the supply port 41 at the bottom of the first liquid tank 4a of the container 1 is guided to the side surface of the first liquid tank 4a by the plate 14 and generates a jet along the side surface. Thereby, it is possible to prevent the floating matter such as dirt and dust, or scales brought together with the porous hollow fiber membrane M continuously introduced into the container 1 from adhering to the side surface of the first liquid tank 4a. As a result, it is possible to prevent the bubble detection sensitivity from being lowered due to dirt on the side surface of the first liquid tank 4a.

  The liquid supplied from the supply port 41 to the first liquid tank 4a fills the first liquid tank 4a, overflows from the first liquid tank 4a to the second liquid tank 4b, and always has a constant liquid level. keep. The overflowing liquid is sucked and discharged from the discharge port 42 by the water ring vacuum pump 2. The liquid L discharged from the discharge port 42 is guided to the liquid discharge tank 17.

  A liquid discharge opening / closing valve 18 may be provided between the discharge port 42 and the liquid discharge tank 17. The liquid discharge on / off valve 18 can be closed to shut off the liquid discharge tank 17 from the decompression space in the container 1, and the liquid L can be discharged from the liquid discharge tank 17.

  In the flange portion 5 of the container 1, an introduction port 51 for continuously introducing the porous hollow fiber membrane M produced in the manufacturing process into the container 1, and the porous hollow fiber M continuously from the container 1. And a lead-out port 52 for lead-out. The inlet 51 and the outlet 52 each have a non-contact seal structure.

  In order to maintain the sealed space formed by the liquid tank 4 and the flange portion 5 in a reduced pressure state, the clearance around the porous hollow fiber membrane M at the inlet 51 and outlet 52 is important. This clearance is desirably small in order to suppress the inflow of air as much as possible. However, if the clearance is too small, minute vibrations may occur due to velocity spots of air flowing in with the porous hollow fiber membrane M. In that case, the porous hollow fiber membrane M may slide at the inlet 51 and outlet 52, and the surface of the porous hollow fiber membrane may be damaged.

  Considering such points, the clearance is preferably about 0.1 mm to 2 mm. Furthermore, from the viewpoint of maximally depressurizing the sealed space, the seal flow rate of the non-contact portion in the seal structure is preferably sealed at a critical flow rate, and the clearance is more preferably about 0.1 mm to 1 mm.

Furthermore, the seal structure is preferably a labyrinth seal that can ensure high sealing performance.
The type of labyrinth seal is not particularly limited, and various types such as a direct-through type and a staggered type that are often used as a basic structure can be used.

As a specific example, the container 1 is composed of a glass container 4 and a stainless steel flange portion 5, and the inlet 51 and the outlet 52 of the flange portion 5 each have a diameter of 2.8 mm (clearance of 0.2 mm). 35 mm) direct labyrinth seal structure. The inner space of the container 1 is a water-sealed vacuum pump (manufactured by Shinko Seiki Co., Ltd., trade name: water-sealed vacuum pump SW-150S, exhaust speed 2.5 m ³ / min, ultimate pressure 2.3 kPa) 2 Therefore, the air is exhausted from the exhaust port 53 and the pressure is reduced.

In addition, the sealing flow velocity of each of the inlet port 51 and the outlet port 52 having a direct labyrinth seal structure is assumed that the critical flow velocity when the clearance area per porous hollow fiber membrane is 3.46 mm ² is 330 m / sec. The limit leakage amount per hole is 68.6 L / min. Accordingly, when the introduction port 51 and the discharge port 52 are provided in four holes, the total leakage amount is 549 L / min or more with a total of eight holes. Since this value is sufficiently smaller than the pumping speed of the vacuum pump 2 of 2.5 m ³ / min, it can be seen that the inlet 51 and the outlet 52 are sealed at the limit flow velocity.

  By the way, in the present invention, in the liquid under reduced pressure, the air sucked out from the hollow portion of the porous hollow fiber membrane is detected as bubbles, so the hydrophilicity and hydrophobicity of the porous hollow fiber membrane to be inspected are adjusted. It doesn't matter. Moreover, there is no restriction | limiting in the material, fractionation characteristic, etc. of a porous hollow fiber membrane, What is necessary is just to be able to be used as a filtration membrane. Examples of the material for the porous hollow fiber membrane include polyethylene, polysulfone, polyvinylidene fluoride, and cellulose. The size of the porous hollow fiber membrane is not limited, but for example, the outer diameter is about 0.5 to 5 mm, the inner diameter is about 0.3 to 4.9 mm, and the fractionation characteristic is 0.05 to 0.5 μm. Some of them can be mentioned.

Furthermore, as a specific example of the hydrophilic porous hollow fiber membrane M, the inner diameter is 1000 μm, the outer diameter is 2100 μm, and the surface thereof is made of polyvinylidene polyfluoride coated with a hydrophilic polymer. The fractional pore diameter is 0.4 μm, A water-passing performance is 100 m ³ / m ² / hr / MPa.
In addition, when the material of the porous hollow fiber membrane is hydrophobic, it is desirable to perform a hydrophilic treatment.

  By the way, the thread diameter of the portion where the porous hollow fiber membranes M are connected to each other is as thick as about 10 mm, for example. When continuously inspecting the porous hollow fiber membrane, when a portion having a large yarn diameter is introduced into the defect inspection apparatus, the porous hollow fiber membrane M comes into contact with the edges of the inlet 51 and the outlet 52, A situation may occur in which the porous hollow fiber membrane M cannot pass through these openings. Therefore, in order to avoid the occurrence of such a situation, the defect inspection apparatus according to the present embodiment includes a yarn diameter detecting means 7 and an automatic opening / closing mechanism 8.

  The yarn diameter detection means 7 is provided on the upstream side of the introduction port 51 and detects the thickness of the porous hollow fiber membrane M introduced into the container 1. The yarn diameter detecting means 7 is not limited as long as it is a means capable of detecting the yarn diameter, and for example, a device using a laser or a device using image processing can be used. In the present embodiment, as the yarn diameter detecting means 7, a product made by Keyence, product name: ultra-small digital laser sensor LX2-V10 is arranged. In this sensor 7, a light emitter and a light receiver (not shown) are arranged with the porous hollow fiber membrane M interposed therebetween, and the porous hollow fiber membrane M is determined by the amount of light shielded by the porous hollow fiber membrane M. The outer diameter of the is detected.

  For example, when a light shielding amount exceeding the outer diameter of 2.4 mm of the porous hollow fiber membrane M is incident on the light receiver of the sensor 7, an automatic opening / closing mechanism is provided according to the detected thickness of the porous hollow fiber membrane M. 8 operates, and the opening diameters of the inlet 51 and the outlet 52 are temporarily enlarged. Thereby, there is no clearance, and it is possible to prevent the porous hollow fiber membrane M from coming into contact with the defective product or preventing the porous hollow fiber membrane M from passing therethrough.

  As shown in FIG. 3, the automatic opening / closing mechanism 8 that adjusts the opening diameter of each of the inlet 51 and the outlet 52 includes a labyrinth seal portion 80, a centering mechanism 81, and a drive mechanism 82. Has been.

  The centering mechanism 81 is composed of two plates disposed on the labyrinth seal portion 80 so as to sandwich the porous hollow fiber membrane M from both sides. The centering mechanism 81 guides the porous hollow fiber membrane M so that the porous hollow fiber membrane M passes through the center of the opening of the labyrinth seal portion 80. In particular, when the opening of the labyrinth seal portion 80 is once expanded by the centering mechanism 81 and returned to the original opening diameter, the porous hollow fiber membrane M passes through the centers of the inlet 51 and outlet 52 again. Can be.

  The drive mechanism 82 is composed of, for example, an air cylinder, a hydraulic cylinder, a rotary actuator, or the like, and drives the half labyrinth seal portion 80 and the centering mechanism 81 to adjust the opening diameter. The drive mechanism 82 causes the labyrinth seal portion 80 and the centering mechanism 81 disposed at the upper portion thereof to be guided by a lower guide groove (not shown) to perform a straight movement, and move and stop in the center direction.

  Then, when the yarn diameter detecting means 7 detects a portion where the outer diameter of the porous hollow fiber membrane M is abnormally thick, it automatically opens and closes in accordance with the timing when the thick portion passes through the inlet 51 and outlet 52. The drive device 82 of the mechanism 8 operates. As a result, the labyrinth seal portion 80 and the centering mechanism 81 move in directions away from the center direction, and the opening diameter is temporarily enlarged. Thereby, even if there is an abnormally thick portion in the porous hollow fiber membrane M, it is possible to avoid an abnormality in which the thick portion comes into contact with the inlet 51 and the outlet 52 or cannot be passed due to being caught. .

  The opening diameter may be enlarged after a certain time from the detection time of the thick part by the yarn diameter detecting means 7 or the inspection speed is detected in accordance with the inspection speed (line speed of the porous hollow fiber membrane). Then, the time when the thick part passes through the inlet 51 and the outlet 52 may be calculated, and the opening diameter may be enlarged at the calculated time.

  Moreover, there is no restriction | limiting in particular in the material of the automatic opening / closing mechanism 8 and the centering mechanism 81, For example, resin, such as polyester, polyvinyl chloride, polyethylene, polyamide, a polypropylene, a polyacetal, iron, aluminum, copper, stainless steel, nickel, titanium Such metals, alloys, or composite materials thereof can be used.

  The continuous dipping means 3 is composed of six guide rolls 31-36. The porous hollow fiber membrane M is guided by these guide rolls 31 to 36 and continuously introduced from the outside of the container 1 to the internal space and accommodated in the internal space of the container 1 as shown in FIG. It passes through the liquid L and is led out from the internal space of the container 1 to the outside.

  Between the guide roll 33 and the guide roll 34, the porous hollow fiber membrane M passes through the liquid L accommodated in the internal space of the container 1 at a certain depth from the liquid level. In this way, by keeping the liquid depth of the porous hollow fiber membrane that passes through the liquid constant, the fluctuation of the pressure applied to the porous hollow fiber membrane that passes through the liquid is suppressed and made constant, and the porous hollow fiber membrane The defect detection accuracy can be made constant.

  In this embodiment, the porous hollow fiber membrane M is continuously run in the liquid L at a running speed of about 7 m / min at a water depth of about 30 to 40 mm over a distance of about 400 mm.

  And when the porous hollow fiber membrane which has defects, such as a pinhole, passes in the liquid under pressure reduction, gas will be sucked out from a defective part. The sucked out gas becomes bubbles in the liquid. Bubbles are usually generated one after another from the defective portion and rise upward above the porous hollow fiber membrane. By detecting the bubbles, defects in the porous hollow fiber membrane can be detected. In order to detect this bubble, this defect detection apparatus includes a bubble detection means as described below.

  In the present embodiment, the bubble detecting means 11 includes a transmissive photoelectric sensor including a light projecting unit 11a and a light receiving unit 11b. Here, a fiber unit (KEYENCE FU-12) of an optical fiber type area transmission photoelectric sensor using a red LED as a light source is used, and the output of the sensor 11 is an amplifier (Keyence product name: Dual Digital Fiber Sensor FS). -V21RM) (not shown). Laser type and optical fiber type photoelectric sensors are preferable from the viewpoints of ease of adjustment, versatility, and the like. In addition, the area type sensor is preferable from the viewpoint of widening the detection range with respect to the flow direction of the porous hollow fiber membrane M.

  The light projecting portion 11a and the light receiving portion 11b of the bubble detecting means 11 may be arranged outside the side wall of the container 1 so as to face each other across the upper liquid L portion where the porous hollow fiber membrane M travels. . In this case, the parallel light emitted from the light projecting unit 11a is blocked by the bubbles, and the amount of light received by the light receiving unit 11b is reduced, whereby the bubbles can be detected.

  Further, the light projecting unit 11a and the light receiving unit 11b of the bubble detecting means 11 may be arranged such that their optical axes substantially intersect above the passage position in the liquid of the porous hollow fiber membrane. In that case, the angle of the light projecting unit 11a that projects parallel light onto the bubbles in the liquid is directed upward or downward to remove the optical axis from the light receiving unit 11b, or the light projecting unit 11a that projects parallel light onto the bubbles in the liquid. It is preferable to receive light scattered by bubbles by removing the optical axis with the angle of the light receiving portion 11b upward or downward. In general, higher detection sensitivity can be expected in the method of detecting bubbles by the roller that receives scattered light from the bubbles than in the method of detecting bubbles by shielding light from the bubbles.

  However, when scattered light is received, it is easily affected by disturbance light. However, if the portions other than the portions facing the light projecting portion 11a and the light receiving portion 11b on the side wall of the liquid tank 4 are shielded, the influence of disturbance light can be reduced.

  Furthermore, in this embodiment, the signal processing apparatus 12 which performs the differential process of the output signal from amplifier of the photoelectric sensor 11 which is the bubble detection means 11 is provided. Here, a graphic analog controller RJ-800 manufactured by Keyence Corporation is used as the processing device 12. By differentiating the output signal, the instantaneous change in the amount of received light due to the passage of bubbles generated from the defective portion of the porous hollow fiber membrane M, the dirt adhering to the inner wall of the liquid tank 4 as a noise source, A long-term change in the amount of received light due to bubbles can be distinguished. Thereby, the reliability of defect detection can be improved.

  Then, the processing device 12 may monitor the bubble generation status and display it directly, and if a bubble is detected, a bubble detection signal may be output to notify the occurrence of a defect with an indicator lamp, buzzer, or the like. Furthermore, after the part in which the defect in the porous hollow fiber membrane M is detected has come out of the inspection apparatus, the defect occurrence part may be marked. This marking can be performed at a timing delayed for a certain time in consideration of the inspection speed of the porous hollow fiber membrane M from the time of defect detection. Thereby, since the position of the defect part of a porous hollow fiber membrane is pinpointed, defect repair and cutting | disconnection removal work can be performed easily.

  In addition to the transmission photoelectric sensor, a reflection photoelectric sensor can be used as the bubble detection means 11. The bubble detection means 11 is not limited to a photoelectric sensor, and is not particularly limited as long as it can detect the generation of bubbles in the liquid. For example, a bubble detector using ultrasonic waves or a bubble detector using image processing may be used.

  As shown in FIG. 4A, the ultrasonic sensor detects bubbles by transmitting ultrasonic waves from the sensor head and receiving ultrasonic waves reflected by the bubbles. Moreover, if an ultrasonic sensor is used, the distance from a sensor to a bubble can be calculated | required by measuring the time from transmission of this ultrasonic wave to reception. Furthermore, by performing differential processing on the received signal by the differential processing device 12, it is possible to improve the detection accuracy of bubbles. As shown in FIG. 4B, the ultrasonic sensor may be disposed on the side surface of the container.

  Further, when detecting bubbles by image processing, as shown in FIG. 5, the bubbles may be imaged from above the container 1 by an image sensor 111 such as a CCD camera. A video signal output from the image sensor is input to the image processing device 112. The image processing device 112 performs various preprocessing such as binarization processing on the video signal, and then extracts features such as the area, length, number, and position of the symmetrical object. Furthermore, the image processing apparatus 112 compares the extracted feature with the set reference, determines the presence or absence of bubbles, and outputs the determination result.

  When an image sensor is used as the bubble detection means, it is desirable to make at least a part of the flange 5 of the container 1 transparent and illuminate the inside of the liquid tank 4 with the illumination device 113 from the side.

  In the present embodiment, defects in the four porous hollow fiber membranes M are detected simultaneously. For this reason, the continuous dipping means 3 is provided with four guide rolls 31 to 36 in parallel, guides the four porous hollow fiber membranes M that run in parallel, and runs in parallel in the liquid L contained in the container 1. ing. In such a case, it is necessary to distinguish which one of the four porous hollow fiber membranes M is sucked out of the four porous hollow fiber membranes M. Therefore, in the present embodiment, a separator 13 for separating bubbles sucked from different porous hollow fiber membranes is provided in the internal space of the container 1.

  Here, FIG. 6 schematically shows a perspective view of the separator. The separator 13 is made of stainless steel, and has a lower partition 13b extending between adjacent porous hollow fiber membranes along the traveling direction of the four porous hollow fiber membranes M1 to M4 on the lower surface of the plate 13a. And an upper partition 13c that extends along a direction perpendicular to the traveling direction of the porous hollow fiber membrane on the upper surface of the plate 13a. By the upper partition 13c, the upper surface of the plate 13a is divided into four sections 131 to 134 having the same number as the number of the porous hollow fiber membranes.

  Furthermore, the plate 13a is provided with four openings 13d leading to different upper compartments for each porous hollow fiber membrane between the lower partitions. That is, the upper four sections 131 to 134 correspond one-to-one with the four porous hollow fiber membranes M1 to M4 between the lower partitions through different openings 13d-1 to 13d-4. As a result, bubbles generated from defective portions of different porous hollow fiber membranes always rise to different compartments 131 to 134 through different openings 13d. Therefore, the porous hollow fiber membrane having a defective portion can be specified by the section where the bubbles are detected.

  Therefore, in this embodiment, a pair of bubble detection means 11 (11a and 11b) is individually provided for each of the four sections 131 to 134. As a result, for example, bubbles generated from the defective portion of the porous hollow fiber membrane M1 rise to the partition 131 through the opening 13a and are detected by the bubble detection means 11a-1 and 11b-1. Further, for example, bubbles generated from the defective portion of the porous hollow fiber membrane M2 rise to the partition 132 through the opening 13b and are detected by the bubble detection means 11a-2 and 11b-2.

  As described above, since the bubbles generated from the defective portions of the different porous hollow fiber membranes can be completely separated from each other, even when a plurality of porous hollow fiber membranes are run in parallel, Defects can be detected individually for each yarn film.

  In the present embodiment, the separator 13 is made of stainless steel, but the material of the separator 13 is not particularly limited. For example, resins such as polyester, polyvinyl chloride, polyethylene, polyamide, polypropylene, polyacetal, iron, aluminum, copper Metals such as nickel and titanium, alloys, or composite materials thereof may be used.

Further, the shape of the separator is not limited to that shown in FIG. For example, in the separator shown in FIG. 6, the upper partition 13c may be omitted.
Even if no separator is provided, as shown in FIGS. 7 (a) and 7 (b), if individual bubble detection means are arranged for each of the parallel running porous hollow fiber membranes, Defects can be detected individually for each hollow fiber membrane. In the example shown in FIG. 7 (a), as shown in FIG. 7 (b) in a cross section taken along the dashed line AA in FIG. 7 (a), it is seen in plan view above each porous hollow fiber membrane M. Then, as shown in FIG. 7A, a pair of bubble detection means (for example, a light projecting part and a light receiving part) are arranged so as to sandwich the porous hollow fiber membrane.

  Moreover, in the example shown in FIG.7 (c), as shown in the cross section along the dashed-dotted line BB in FIG.7 (c) in FIG.7 (d), just above each porous hollow fiber membrane M, A pair of bubble detection means (for example, a light projecting part and a light receiving part) are arranged along the porous hollow fiber membrane M, respectively.

  As described above, according to the defect inspection apparatus of the present embodiment, only the hydrophobic or hydrophilic porous hollow fiber membrane is continuously passed through the liquid contained in the decompressed container containing the liquid. Thus, bubbles from defects in the porous hollow fiber membrane can be detected. And since the defect of the porous hollow fiber membrane can be continuously detected, in the subsequent process, if marking is performed in the vicinity of the defect portion detected by this defect inspection apparatus, and the portion is removed, the defect is substantially completely absent. A porous hollow fiber membrane can be obtained. Furthermore, by incorporating a defect inspection apparatus into the manufacturing process, defects generated in manufacturing can be repaired, and the yield of manufacturing the porous hollow fiber membrane can be improved.

  In each embodiment mentioned above, although the example which constituted the present invention on specific conditions was explained, the present invention can perform various change and combination, and is not limited to this.

It is a longitudinal cross-sectional schematic diagram of the defect inspection apparatus of embodiment. It is a cross-sectional schematic diagram along line II-II of the defect inspection apparatus shown in FIG. It is a schematic diagram which shows the sealing structure of the inlet of a container. (A) is a schematic diagram of an ultrasonic sensor, (b) is explanatory drawing of arrangement | positioning of an ultrasonic sensor. It is explanatory drawing of arrangement | positioning of an image sensor. It is a perspective view of a separator. (A) is a plane schematic diagram which shows arrangement | positioning of the bubble detection means in a modification, (b) is a cross-sectional schematic diagram along the dashed-dotted line AA of (a), (c) is others It is a plane schematic diagram which shows arrangement | positioning of the bubble detection means in the modification of (d), (d) is a cross-sectional schematic diagram along the dashed-dotted line BB of (c).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Container 2 Pump 3 Continuous immersion means 4 Liquid tank 4a 1st liquid tank 4b 2nd liquid tank 5 Flange 6 Seal part 7 Thread diameter detection means 8 Automatic opening / closing mechanism 9 Filtration apparatus 10 Deaeration apparatus 11 Bubble detection means 11a Light projection part 11b Light receiving unit 12 Differential processing device 13 Separator 13a Plate 13b Lower partition 13c Upper partition 13d Opening 14 Jet means 15 Supply on / off valve 16 Supply control valve 17 Liquid discharge tank 18 Liquid discharge on / off valve 31 to 36 Guide roll 40 Partition plate 41 Supply port 42 Discharge port 43 Exhaust port 51 Inlet port 52 Outlet port 53 Exhaust port 80 Labyrinth seal part 81 Centering mechanism 82 Drive mechanism 110 Ultrasonic sensor 111 CCD camera 112 Image processing device 131-134 Section

Claims (7)

A defect inspection device for a porous hollow fiber membrane,
A container constituting an internal space in which a liquid tank containing liquid is disposed ;
And decompression means for decompressing the internal space,
The porous hollow fiber membrane is continuously introduced so as to be introduced into the internal space from the outside of the container , passed through the liquid under reduced pressure stored in the liquid tank, and led out from the internal space of the container to the outside. Continuous dipping means for conveying to,
A bubble detection means for detecting bubbles sucked into the liquid from a defective portion of the porous hollow fiber membrane passing through the liquid;
Liquid supply means for supplying the liquid to the liquid tank, so that the liquid in the liquid tank maintains a liquid level with a certain height.
A defect inspection apparatus for a porous hollow fiber membrane characterized by the above. The liquid supply means, a supply-off valve for switching the open and closed states of the supply port, a supply control valve to adjust the supply amount of liquid to the liquid tank, Ru Tei provided with,
The defect inspection apparatus for the porous hollow fiber membrane according to claim 1 . The liquid supply means includes a filtration device for filtering the liquid, and a deaeration device for removing bubbles in the liquid.
The defect inspection apparatus for a porous hollow fiber membrane according to claim 1 or 2 . Jetting means for jetting the liquid supplied from the liquid supplying means along the wall surface of the liquid tank facing the bubble detecting means;
Defect inspection apparatus of the porous hollow fiber membrane according to any one of claims 1 to 3. The container is provided with an inlet through which the porous hollow fiber membrane introduced into the internal space passes, and an outlet through which the porous hollow fiber led out from the internal space passes,
The introduction port and the discharge port each have a non-contact type seal structure ,
The defect inspection apparatus for a porous hollow fiber membrane according to any one of claims 1 to 4 . The sealing structure is sealed at a critical flow velocity.
The defect inspection apparatus for a porous hollow fiber membrane according to claim 5. The continuous dipping means allows a plurality of porous hollow fiber membranes to pass through the liquid ,
Said container, said interior space, Ru Tei includes a separator for separating the air bubbles each other sucked out from each of different porous hollow fiber membrane,
The defect inspection apparatus for a porous hollow fiber membrane according to any one of claims 1 to 6.

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