Valve seat inspection method and valve seat inspection device using image recognition camera

Abstract

To provide a valve seat inspection method and a valve seat inspection device using an image recognition camera which can automatically continuously execute a valve seat inspection of a valve with a simple configuration, highly accurately and easily detect a very small leakage amount from a valve seat with the image recognition camera even if the high valve seat leakage performance is requested, and exhibit inspection accuracy equivalent to a case of visually performing the valve seat inspection on a valve in a submerged state by means of visual inspection.SOLUTION: An inspection device body 1 which includes a checking circuit 10 that checks leakage of a reference leakage amount, an inspection circuit 11 in a state where a test valve 20 is installed and an image recognition camera 12 that images bubbles appearing from a tip 21a by inserting an inspection tube 21 to water in a container 22 performs: a checking step of determining whether or not the bubbles appear from the tip 21a of the inspection tube within a checking time with the image recognition camera by switching a circuit switching unit 23; and an inspection step of determining whether or not the bubbles appear from the tip of the inspection tube within the inspection time with the image recognition camera by switching the circuit switching unit.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to a method for inspecting a valve seat of a valve, and more particularly, to a valve seat inspection method and a valve seat inspection apparatus using an image recognition camera capable of detecting a minute leakage amount from the valve seat with high accuracy by automatic inspection.

Background Art

[0002] Generally, after manufacturing a valve, a valve seat inspection is performed on this valve by a valve seat leakage test to confirm whether the valve meets the standards as a product. When automatically inspecting a general valve for its valve seat, an inspection method using air pressure is known. For example, when inspecting the valve seat leakage of a ball valve, it may be performed using a valve seat inspection apparatus equipped with a flow sensor and a flow standard. In this valve seat inspection apparatus, a flow standard, a solenoid valve for switching the flow path, a clamp for attaching the valve, and a flow sensor for measuring the flow rate are provided in the inspection flow path. The flow standard is provided to adjust the air pressure from an air pump provided on the primary side to a reference leakage amount (pressure serving as a reference for the leakage inspection) and supply it to the secondary side. The solenoid valve is provided so that it can supply the air pressure from the flow standard to the test valve side or switch to a supply stop state. The flow sensor is provided so that it can measure the valve seat leakage amount from the test valve.

[0003] Before performing a valve seat inspection on a ball valve (test valve) with the above valve seat inspection apparatus, usually, appropriate setting of the inspection flow path and inspection of whether the flow sensor is functioning properly are performed. When performing this inspection, compressed air adjusted to the reference leakage amount by the flow standard is sent to the flow sensor, thereby checking the flow sensor and the flow path. Subsequently, when performing a valve seat inspection, with both sides of the test valve clamped, the air flow (leakage amount from the valve seat) generated from both sides of the test valve in a valve-closed state with pressure sealed inside the cavity is measured by the flow sensor.

[0004] On the other hand, Patent Document 1 discloses a technology for an airtightness inspection method using a workpiece airtightness inspection device. This inspection device uses a camera for image recognition to inspect the airtightness of a workpiece consisting of a hollow container, and includes a workpiece storage capsule consisting of a capsule lid and a capsule body, an air supply passage connected to a pressurizing device that supplies air to the inner space of the workpiece, a workpiece placement device having an air inlet passage that pressurizes the space inside the capsule and an air outlet passage that allows the air inside the capsule to flow out, and a bubble confirmation device consisting of a liquid storage tank and a bubble measuring device that measures the gas from the air outlet passage as bubbles. As an example of the bubble measuring device, a video camera and a lighting device are combined, and the video camera is used to detect bubbles generated in the liquid storage tank.

[0005] When performing airtightness testing on a workpiece, the workpiece is placed inside a capsule, and the inside of the capsule is pre-pressurized through an air inlet. Once the pressure inside the capsule and the pipeline has increased, the internal space of the workpiece is pressurized with a pressurizing device, causing the air inside the capsule to be released as bubbles into the liquid in the liquid storage tank. The bubbles generated at this time are detected by a video camera, and the amount of bubbles generated is compared with a predetermined amount of bubbles in the case of no leaks to determine the airtightness of the workpiece.

[0006] Furthermore, in the leakage amount measuring device described in Patent Document 2, leakage from a valve is accumulated in a container (cylinder) by water displacement, and the liquid level in the cylinder, which has dropped due to this accumulated leakage fluid, is measured with an ultrasonic sensor, and the amount of leakage is measured from the change in the water level.

[0007] Incidentally, each valve product must pass the aforementioned valve seat leakage test based on the standards defined in the prescribed specifications. In particular, valves used for industrial applications, such as those carrying chemical fluids (hereinafter referred to as "industrial valves"), require higher sealing performance compared to valves used for general-purpose applications such as water supply and hot water supply (hereinafter referred to as "general-purpose valves"). In this case, in order for industrial valves to exhibit higher leakage prevention performance, it is necessary to test the valves based on stringent judgment criteria.

[0008] In this case, when inspecting the valve seat, the common method involves submerging the valve, into which air has been supplied, in water, and having an operator visually check the leaking bubbles to determine whether or not there is a valve seat leak. [Prior art documents] [Patent Documents]

[0009] [Patent Document 1] Patent No. 3850273 [Patent Document 2] Japanese Patent Application Publication No. 7-260541 [Overview of the Initiative] [Problems that the invention aims to solve]

[0010] However, visually inspecting valve seat leaks requires skilled operators, and the results may vary from operator to operator, with the possibility of overlooking leaks. In addition, valve seat inspection cannot be automated, and the inspection of each valve seat is time-consuming.

[0011] On the other hand, when performing valve seat inspection of industrial valves using a valve seat inspection device with a flow sensor, this flow sensor must have the detection capability to measure extremely small amounts of leakage that cannot be detected by visual inspection, for example, leakage of 0.2 mL / min or less. However, the minimum measurement capability of general-purpose flow sensors is often greater than 0.2 mL / min, and they cannot measure extremely small leak volumes of 0.2 mL / min or less. There are virtually no general-purpose flow sensors capable of measuring such values. Therefore, valve seat inspection devices using general-purpose flow sensors cannot guarantee the leakage performance of valve seats, such as industrial valves requiring high sealing performance, compared to visual inspection by submersion. Furthermore, even if an attempt were made to create a high-precision flow sensor capable of measuring flow rates of 0.2 mL / min or less, it would be impractical due to problems such as increased internal structure complexity, larger overall size of the inspection device, and increased costs for calibration of the flow sensor. When checking whether a flow sensor is functioning correctly, a problem arises because calibration is extremely difficult due to the high precision required for this flow sensor.

[0012] The workpiece airtightness testing device described in Patent Document 1 uses a sealed hollow container as the test object, generates bubbles as leakage from the hollow container, measures the amount of bubbles, and compares this amount of bubbles to a preset amount to test the airtightness of the hollow container. This testing device detects the difference in the amount of bubbles from the hollow container when air is continuously applied from the outside using a video camera, and measures only whether or not leakage occurs. It cannot measure minute amounts of leakage from the workpiece with a video camera. For this reason, it is difficult to use it as a testing device for inspecting minute valve seat leaks in industrial valves and the like.

[0013] In addition, when performing airtightness testing with the inspection device described in Document 1, it is necessary to support and fix the workpiece inside the capsule, and to attach the capsule lid to the capsule body in a sealed state, while simultaneously connecting the tip of a conduit, which is provided on the capsule lid side and connected to a pressurizing device, to the opening of the workpiece in a sealed state. Thus, the structure for attaching and detaching the workpiece is complex, and it is also necessary to pre-pressurize the inside of the capsule for each workpiece to set the predetermined pressure, making it difficult to automate the inspection and difficult to perform continuous valve seat inspection of workpieces.

[0014] Furthermore, in the case of Patent Document 2, a high-precision ultrasonic sensor is required to measure the liquid level inside the cylinder, which also complicates the inspection device. In addition, when performing inspections using sensors that measure physical quantities, such as ultrasonic sensors, it is necessary to accurately measure the actual values ​​in order to correctly determine whether the inspection is successful or not, which requires fine calibration and adjustment of the sensors. Moreover, a function may be needed to compare the actual values ​​with the leakage amount judgment value that serves as the criterion for success or failure.

[0015] For these reasons, there has been a need for the development of a valve seat inspection method and inspection device that can automatically and continuously inspect valves requiring high valve seat performance, such as industrial valves, without submerging the valve in water and performing a visual inspection, while maintaining the same level of inspection accuracy as this visual inspection.

[0016] The present invention was developed to solve the problems of the past, and its objective is to provide a valve seat inspection method that enables continuous automated inspection of valve seats with a simple configuration, and to provide a valve seat inspection method and valve seat inspection device that can detect even the slightest amount of leakage from the valve seat with high accuracy and ease using an image recognition camera without using a high-precision sensor, even for valves that require high valve seat leakage performance such as industrial valves, and can achieve inspection accuracy equivalent to that of visually inspecting a valve seat while it is submerged in water. [Means for solving the problem]

[0017] To achieve the above objective, the invention according to claim 1 is a valve seat inspection method using an image recognition camera, comprising an inspection circuit for checking the leakage of a standard leak amount, an inspection circuit with a test valve installed, and an inspection device body having an image recognition camera that inserts an inspection tube into water in a container and photographs bubbles that appear from the tip of the inspection tube, wherein the inspection process involves switching a circuit switching unit to determine whether or not bubbles appear from the tip of the inspection tube within the inspection time using the image recognition camera, and switching a circuit switching unit to determine whether or not bubbles appear from the tip of the inspection tube within the inspection time using the image recognition camera.

[0018] The invention according to claim 2 is a valve seat inspection method using an image recognition camera configured to perform at least any one or all of water level determination by image processing, water level determination by a weight sensor, large leak determination by a flow sensor, and determination of the insertion depth of an inspection tube by image processing as pre-steps of an inspection process and an inspection process.

[0019] The invention according to claim 3 is a valve seat inspection method using an image recognition camera configured to blow low-pressure air into an inspection tube to discharge water adhering to the tip of the inspection tube.

[0020] The invention according to claim 4 is a valve seat inspection method using an image recognition camera configured to operate, by an operation mechanism unit, steps of inserting the tip of an inspection tube into water and steps of opening to the atmosphere.

[0021] The invention according to claim 5 is a valve seat inspection method using an image recognition camera configured to coat an inspection device main body and its inner wall with a non-reflective paint that prevents reflection of light to obtain the detection performance of the image recognition camera.

[0022] The invention according to claim 6 is a valve seat inspection device using an image recognition camera, comprising: an inspection circuit for inspecting leakage of a reference leakage amount; an inspection circuit in a state where a test valve is installed; an image recognition camera for photographing bubbles emerging from the tip of an inspection tube inserted into a container filled with water and communicating with the inspection circuit; a circuit switching unit for switching between the inspection circuit and the inspection circuit; and an operation mechanism unit for inserting the inspection tube into water and opening to the atmosphere.

[0023] The invention according to claim 7 is a valve seat inspection device using an image recognition camera configured to perform at least determination of leakage based on the presence or absence of bubbles emerging from the tip of an inspection tube, determination of the water level in a container, and determination of the insertion depth of the inspection tube.

[0024] The invention according to claim 8 is a valve seat inspection device using an image recognition camera, wherein the operation mechanism unit is a linear servo mechanism that operates vertically.

[0025] The invention according to claim 9 is a valve seat inspection device using an image recognition camera provided with a low-pressure air blowing portion in an inspection tube to discharge water adhering to the tip of the inspection tube.

Advantages of the Invention

[0026] According to the invention according to claim 1, valve seat inspection of a valve can be continuously carried out by automatic inspection with a simple configuration. Even when high valve seat leakage performance is required, such as for industrial valves, even without using a high-precision sensor, a very small leakage amount from the valve seat can be detected with high precision and simply using a simple image recognition camera. In this case, by photographing bubbles with the image recognition camera, leakage can be visually detected in the same way as when visually inspecting the valve seat of a submerged valve, and inspection can also be carried out according to a predetermined standard so as to exhibit inspection accuracy equivalent to this submerged visual inspection. Thereby, even when the criteria for determining valve seat leakage are strict, it becomes possible to extremely accurately determine the pass or fail of the valve product. Moreover, the state of leakage of the reference leakage amount can be easily inspected in advance in the inspection process, and the inspection process can be carried out more accurately based on this inspection. Furthermore, in any case of the inspection process and the inspection process, since the inspection tube can be opened to the atmosphere and then the circuit switching portion can be switched, inspection and inspection can be carried out in a state where the influence of the air flow in the inspection tube and the influence due to the pressure difference between the outside air (atmospheric pressure) and the pressure inside the inspection tube are minimized, and it becomes possible to provide a high-quality valve with valve seat leakage suppressed to the limit.

[0027] According to the invention of claim 2, if water level determination is performed by image processing and water level determination is performed by a weight sensor as pre-inspection and inspection steps, the amount of water in the container can be adjusted to a constant amount in each step by replenishing or removing water according to the determination results, thereby maintaining a constant water pressure when bubbles appear from the tip of the tube. If a large leak is detected by a flow sensor, a large leak in the test valve can be confirmed according to this determination result and the valve can be rejected and removed before the inspection step. If the insertion depth of the inspection tube is determined by image processing, the depth of the tip position of the inspection tube can be adjusted according to this determination result, thereby maintaining a constant water pressure when bubbles appear from the tip of the tube. By performing each of these determinations, the conditions for each test valve can be kept constant in both the inspection and inspection steps, enabling highly accurate valve seat inspection.

[0028] According to the invention of claim 3, by blowing low-pressure air into the inspection tube to expel water adhering to the tip of the inspection tube, the inside of the inspection tube and the outside air (atmospheric side) are reliably connected when the tip of the inspection tube is opened to the atmosphere, and after ensuring that the inspection circuit and test circuit are in an atmospheric pressure state, the circuit switching unit can be switched to perform accurate inspection and testing.

[0029] According to the invention of claim 4, the steps of inserting the tip of the inspection tube into the water and releasing it to the atmosphere can be automated by operating the operating mechanism, and in either step, the tip of the inspection tube can be accurately positioned above the water surface. As a result, accurate valve seat inspection can be performed by minimizing the influence of atmospheric pressure during the inspection process, the testing process, and the preceding processes such as when attaching and detaching the test valve.

[0030] According to the invention of claim 5, by applying an anti-reflective coating that prevents light reflection, the difference in brightness between the inspection device body and its inner wall coated with this anti-reflective coating, the tip of the inspection tube, the bubbles that appear on this tip, and the water surface in the container can be increased, thereby significantly improving the detection performance of bubbles appearing from the tip of the inspection tube, and also making it possible to easily measure the water level in the container.

[0031] According to the invention of claim 6, a valve seat inspection of a valve can be performed automatically and continuously with a simple configuration. Even in cases where high valve seat leakage performance is required, such as for industrial valves, even the slightest amount of leakage from the valve seat can be detected with high accuracy and ease using an image recognition camera without the need for high-precision sensors. In this case, by photographing bubbles with the image recognition camera, leakage can be detected visually in the same way as when visually inspecting the valve seat of a submerged valve. It is also possible to perform inspections in accordance with predetermined standards to achieve the same inspection accuracy as this submerged visual inspection. As a result, even when the criteria for determining valve seat leakage are strict, it is possible to determine whether a valve product is acceptable or not with extreme accuracy. Moreover, the leakage state of the standard leak amount in the inspection circuit can be easily checked in advance, and this check allows for more accurate inspection. Furthermore, since the circuit switching unit can be switched after opening the inspection tube to the atmosphere using the operating mechanism, it is possible to perform inspections and tests while minimizing the effects of airflow inside the inspection tube and the pressure difference between the outside air (atmospheric pressure) and the pressure inside the inspection tube, thereby providing high-quality valves with valve seat leakage suppressed to the extreme.

[0032] According to the invention of claim 7, since at least the detection of leak bubbles, the determination of the water level, and the determination of the insertion depth of the inspection tube can be performed using only an image recognition camera, the equipment used for valve seat leak detection can be minimized and the overall configuration can be simplified. In both inspection and testing cases, the conditions for each valve under test can be kept constant, enabling highly accurate valve seat inspection.

[0033] According to the invention of claim 8, by using a linear servo mechanism for the operating drive unit, the structure becomes simpler and easier to incorporate. This linear servo mechanism automates the insertion of the tip of the inspection tube into the water and its release into the atmosphere. In either operation, the inspection tube is moved up and down at high speed with high precision while preventing fine vibrations, allowing for rapid and precise control, and the tip of the inspection tube can be accurately positioned above the water surface.

[0034] According to the invention of claim 9, by blowing low-pressure air into the inspection tube from the low-pressure air blowing section and discharging water adhering to the tip of the inspection tube, the inside of the inspection tube and the outside air (atmospheric side) are reliably connected when the tip of the inspection tube is opened to the atmosphere, and the circuit switching section can be switched after ensuring that the inspection circuit and test circuit are in an atmospheric pressure state. [Brief explanation of the drawing]

[0035] [Figure 1] This is a circuit diagram showing one embodiment of a valve seat inspection device. [Figure 2] This is a circuit diagram showing the state when a large leak is detected by the flow sensor. [Figure 3] This is a circuit diagram showing the state of the valve seat inspection device during the inspection process. [Figure 4] This is a circuit diagram showing the state of clearing the inside of the tube of the valve seat inspection device. [Figure 5] This is a circuit diagram showing the state of the valve seat inspection device during the inspection process. [Figure 6] This is a flowchart illustrating the inspection process in the valve seat inspection method using the image recognition camera of the present invention. [Figure 7] This is a flowchart illustrating the inspection process in the valve seat inspection method using the image recognition camera of the present invention. [Figure 8] Figure 6 is a flowchart showing the preparation steps in the inspection process. [Figure 9] Figure 7 is a flowchart showing the preparation steps in the inspection process. [Figure 10] This is a circuit diagram showing another embodiment of the valve seat inspection device. [Modes for carrying out the invention]

[0036] The following describes in detail, with reference to the drawings, an embodiment of the valve seat inspection method and valve seat inspection apparatus using an image recognition camera according to the present invention. Figures 1 to 5 show one embodiment of the valve seat inspection apparatus using an image recognition camera, and the valve seat inspection apparatus will first be described based on these figures.

[0037] In the figure, the valve seat inspection device (hereinafter referred to as the inspection device body 1) is equipped with an air circuit 2 through which air flows. A flow standard 3 is provided near the primary side of the air circuit 2, and a first branch 4 and a second branch 5 are provided on the secondary side of the flow standard 3 so as to branch off, and are provided in a closed circuit manner so as to rejoin after branching. The inspection device body 1 is configured so as to be able to configure either the inspection circuit 10 for inspection shown in Figure 3 or the inspection circuit 11 for valve seat leak inspection shown in Figure 5 by switching the air circuit 2, and comprises these inspection circuits 10 and 11, and an image recognition camera 12. In the air circuit 2, solid lines indicate a state of continuous flow, and dashed lines indicate a state of blocked flow. A jig 13 made of a clamping member is provided at an appropriate position in the second branch circuit 5, and both sides of the test valve 20, which is the object of inspection for valve seat leakage, are connected to this jig 13.

[0038] The inspection device body 1 is further equipped with an inspection tube 21, a container 22, a circuit switching unit 23, a weight sensor 24, a flow sensor 25, an operating mechanism 26, a low-pressure air blowing unit 27, and lighting 28. The inspection device body 1 is designed to clamp both ends of the test valve 20 with a jig 13, and with pressure sealed inside the cavity (not shown) of the test valve 20 in a closed state, it is possible to determine whether the valve seat leaks from both sides using an image recognition camera and determine whether it passes or fails.

[0039] An industrial camera is used as the image recognition camera 12. The image recognition camera 12 has the function of taking still images (triggering) at least at predetermined time intervals, and is positioned and oriented so as to be able to photograph bubbles (leakage bubbles) that appear from the tip 21a of the inspection tube 21, which is connected to the inspection circuit 11, when the tube is inserted into a container 22 filled with water W. In this way, the image recognition camera 12 is provided to perform not only leakage bubble determination, which involves photographing whether or not bubbles appear from the tip 21a of the inspection tube inserted into the water W in the container 22 within a time limit during the inspection and testing processes described later, and determining pass or fail from the photographic results, but also water level determination in the container 22 and determination of the insertion depth of the inspection tube 21. In this embodiment, a single image recognition camera 12 is used to determine the appearance of bubbles from the tip of the inspection tube 21, determine the water level using image processing, and determine the insertion depth of the inspection tube using image processing. However, multiple image recognition cameras may be used (not shown).

[0040] The flow standard 3 is installed on the primary side of the air circuit 2, and an air supply source (not shown) is installed on the primary side of the flow standard 3. The flow standard 3 is installed so that it can supply air from the air supply source to the secondary side after adjusting the pressure to a reference pressure for leak testing, i.e., a reference leak amount.

[0041] The inspection circuit 10 is configured in the air circuit 2 by switching the circuit switching unit 23, and is shown by the solid line in Figure 3. This inspection circuit 10 allows for the pre-checking of a reference leak amount when performing a valve seat leak inspection.

[0042] The inspection circuit 11 is configured in the air circuit 2 by switching the circuit switching unit 23, as shown by the solid line in Figure 5, and the test valve 20 is installed in this inspection circuit 11. After inspection by the inspection circuit 10, the inspection circuit 11 is configured to allow inspection of valve seat leakage of the test valve 20.

[0043] The inspection tube 21 is provided with a predetermined length and inner diameter, allowing air to flow through it at a rate of at least 0.2 mL / min. Here, in this embodiment, the 0.2 mL / min flow rate is an example of a very small amount of leakage that is not visible to the naked eye and indicates virtually no leakage, and is not limited to the above value. One end of the inspection tube 21 is connected to the air outlet side of the air circuit 2, and the other end, tip 21a, is provided to be vertically movable by an operating mechanism 26, which will be described later, so that it can be inserted into the container 22. In this embodiment, the material of the inspection tube 21 is resin or glass, and the color is transparent or white so as to reflect light easily.

[0044] The container 22 is made of a transparent material and is placed below the inspection tube 21, resting on the weight sensor 24, with a predetermined amount of water W filled inside. For example, a transparent glass beaker can be used as the container 22, and a thin, black, anti-reflective material 29 is attached to the side of the container 22 opposite to the side illuminated by the light 28, preventing the reflection of light from the light 28.

[0045] The circuit switching unit 23 is provided by a three-way solenoid valve and is positioned at the branching point of the first branch 4 and the second branch 5 described above. The circuit switching unit 23 switches between the inspection circuit 10 and the test circuit 11 of the air circuit 2. When the flow path is switched to the first branch 4 by the circuit switching unit 23, the aforementioned inspection circuit 10 is configured, while when it is switched to the second branch 5, the aforementioned test circuit 11 is configured.

[0046] The weight sensor 24 is provided so as to be able to place a container 22 filled with water W on it, measure its weight, and determine the water level of the water W from the measured weight.

[0047] In the air circuit 2, switching valves 30 and 31, each consisting of a three-way solenoid valve, are arranged in this order on the secondary side of the confluence point of the first branch 4 and the second branch 5. A flow sensor 25 is connected to the branch portion of switching valve 30, and a low-pressure air injection section 27 is connected to the branch portion of switching valve 31. By switching the switching valves 30 and 31, communication with the flow sensor 25 and the low-pressure air injection section 27 can be established, respectively. In the switching valves 30, 31 and circuit switching valve 23 shown in Figures 1 to 5, only the internal communication flow paths are schematically shown, and other flow paths are omitted.

[0048] The flow sensor 25 is a flow meter capable of measuring the flow rate (mL / min) of air flowing through the air circuit 2 per unit time. When the switching valve 30 is switched to configure the flow path as shown in Figure 2, it measures the leakage flowing out from both sides of the test valve 20 indicated by the arrows through the first branch 4 and the second branch 5. This leakage makes it possible to determine a large flow rate leak from the test valve 20, i.e., a major leak. In the inspection and testing processes, before determining whether or not bubbles appear from the tip 21a of the inspection tube by image judgment, a fast leak rate in the case of a major leak is judged as a failure in advance, preventing the occurrence of a large amount of bubbles rising from the inspection tube 21, which is thought to cause a misjudgment.

[0049] In this example, "large leak" refers to a flow rate greater than the flow rate at which the image recognition camera 12 detects the appearance of bubbles from the tip 21a of the inspection tube during the inspection or testing process. Specifically, it refers to a leakage rate greater than 0.2 mL / min.

[0050] A general-purpose, inexpensive flow sensor 25 with an appropriate detection range can be used; for example, one with a typical capacity of about 0.25 mL / min can be used. In this case, a large leak will be determined when a flow rate of 0.25 mL / min or more flows through the test valve 20.

[0051] The low-pressure air injection unit 27 is an air supply source capable of supplying low-pressure air for a short period of time. Specifically, it is designed to supply air at a pressure of 0.1 MPa or less in less than one second. Figure 4 shows the state in which the switching valve 31 is switched to connect the flow path between the low-pressure air injection unit 27 and the inspection tube 21. When water W adheres to the tip 21a of the inspection tube, in the state shown in Figure 4, low-pressure air is blown in from the low-pressure air injection unit 27 installed on the inspection tube 21a, thereby discharging the water W adhering to the tip 21a of the inspection tube to the outside. The magnitude of the supply pressure of the low-pressure air and the supply time can be arbitrarily set as long as a very small pressure can be supplied from the low-pressure air injection unit 27 for a short period of time.

[0052] The operating mechanism 26 consists of a linear servo mechanism that moves up and down, and the inspection tube 21 is connected to the up and down operating part 26a of the operating mechanism 26 via a connecting part 26b. With this structure, when the operating mechanism 26 is operated, the inspection tube 21 moves up and down together with the up and down operating part 26a, and this movement allows the tip 21a of the inspection tube to be inserted into the water W in the container 22, and also allows the tip 21a of the inspection tube to be withdrawn from the water W in the container 22 and released into the atmosphere.

[0053] The inspection device body 1 and its inner wall 1a are coated with an anti-reflective paint 32 to prevent light reflection. This anti-reflective paint 32 and the aforementioned anti-reflective material 29 prevent light reflection from the illumination 28, thereby improving the detection performance of the image recognition camera 12. The anti-reflective paint 32 and anti-reflective material 29 are provided in, for example, black. The lighting 28 is positioned at an appropriate height on the back side of the image recognition camera 12, for example, at a height that prevents the image recognition camera 12 from directly photographing the light from the lighting 28 reflected by the container 22. The water W in the container 22 is illuminated from this lighting 28 in a direct-light state to photograph the bubbles.

[0054] Although not shown in the diagram, a control unit is connected to the inspection device body 1. Through this control unit, the device controls the switching of the circuit switching unit 23 and switching valves 30 and 31, the operation of the flow standard 3 and operating mechanism 26, the flow rate measurement and major leak detection by the flow sensor 25, the control of image recognition camera 12 to take pictures at predetermined intervals and to determine the water level, the measurement of weight by the weight sensor 24 and to determine the water level based on this weight, the control of supplying or stopping low-pressure air from the low-pressure air blowing unit 27, and the pass / fail determination in the preparation, inspection, and inspection processes. Furthermore, the control unit stores various control data, including comparison data for determination described later, and various determinations are made by comparing with the comparison data, for example. These various data are set up to be updated and stored for each process.

[0055] The test valve 20 whose valve seat is inspected by the valve seat inspection device described above is, for example, a ball valve, and the inspection device body 1 is particularly suitable for inspecting the valve seat of a relatively small ball valve.

[0056] Next, the valve seat inspection method and operation of the valve seat inspection device using the image recognition camera described above will be explained. Figures 6 to 9 show flowcharts of the valve seat inspection method in the present invention. The valve seat inspection method of the present invention comprises an inspection step and an inspection step, and the valve seat of the test valve 20 is inspected by sequentially going through each of these steps. A preparation step is performed as a step prior to each of these inspection and inspection steps.

[0057] The pass / fail criteria for the inspection and testing processes are determined by whether or not the air flowing through the inspection circuit 10 and the testing circuit 11, respectively, produces bubbles from the tip 21a of the testing tube 21 at a predetermined time. In this embodiment, the flow rate is set to 0.2 mL / min. Therefore, the length of the air circuit 2 must be such that it is possible to test whether or not air flowing at a rate of 0.2 mL / min produces bubbles from the tip 21a of the testing tube at a predetermined time. In this embodiment, as will be described later, the test time is set to 30 seconds, and the length of the air circuit 2 is set so that a valve seat leak test can be performed within this test time. The length of the air circuit 2 can be appropriately set according to the type and size of the test valve 20, the size of the standard leak amount which serves as the leak determination criterion. Furthermore, in this embodiment, the flow path of the testing circuit 11 is longer than that of the inspection circuit 10.

[0058] The flowchart shown in Figure 6 illustrates the inspection process from start to finish. When performing a series of valve seat inspections using the inspection device 1, the inspection process is first performed only once, and then the inspection process is repeated according to the number of test valves 20 to be inspected. In this way, by performing the inspection process in advance of the inspection process, it becomes possible to accurately perform valve seat leak testing during the inspection process.

[0059] In Figure 1, before the inspection process, a test valve 20 or a dummy valve (not shown) for valve seat inspection is attached to the first branch line 4 of the air circuit 2 using a jig 13. The test valve 20 is set to a fully open position, and then the preparation process shown in the flowchart of Figure 8 is carried out.

[0060] In Figure 8, the preparation step before the inspection process is performed to confirm that the inspection device body 1, which is a water displacement device, is functioning correctly, and includes at least water level determination by image processing of the image recognition camera 12, water level determination by the weight sensor 24, and determination of the insertion depth of the inspection tube 21 by image processing of the image recognition camera 12. The preparation step only requires performing one or all of these determinations, and in this embodiment, all of these determinations are performed sequentially.

[0061] During the preparation process, the water level determination by image processing is performed with the flow paths in the circuit switching unit 23 and switching valves 30 and 31 shown in Figure 1 connected. At this time, the inspection tube 21 is moved upward by the operating mechanism 26, and the tip 21a of the inspection tube is open to the atmosphere. In the image processing-based water level determination, the image recognition camera 12 takes a single photograph of the water surface W inside the container 22, and the position of this water surface is recognized by the difference in brightness between it and the anti-reflective material 29 on the back side of the container 22 or the anti-reflective paint 32 applied to the inner wall 1a.

[0062] The water level in the photographed container 22 is compared with a preset standard water level. If the water level is within a predetermined range relative to this standard water level, it is deemed acceptable. In this case, the water level is then determined by the weight sensor 24. If the photographed water level is not within the predetermined range, it is deemed unacceptable. In this case, water W is added to or removed from the container 22 to adjust the water level, and then the image processing water level determination is performed again. This process is repeated until the image processing water level determination is successful.

[0063] The water level is determined by the weight sensor 24 by measuring the weight of the container 22 into which water W is poured. The measured weight of the container 22 (including the water W) is compared with a preset standard weight. If the weight is within this standard weight range, it is considered a pass, in which case a major leak is then determined by the flow sensor 25. If the measured weight is not within the predetermined range, it is considered a failure. In this case, similar to water level measurement by image processing, water W is injected into or discharged from the container 22 to adjust the water level, and then the water level is determined again by the weight sensor 24. This process is repeated until the water level determination by the weight sensor 24 is passed.

[0064] The water level in container 22 may change after a few minutes due to evaporation, etc., so it needs to be checked frequently. By performing water level determination using the image processing described above, and water level determination using the weight sensor 24, the water level in container 22 is confirmed using a dual determination criterion of visual and weight, and is adjusted with high precision to prevent changes.

[0065] The flow sensor 25 performs a major leak detection while the flow paths of the circuit switching unit 23 and the switching valve 30 shown in Figure 2 are in communication. At this time, the tip 21a of the inspection tube is kept open to the atmosphere. Air flows from the test valve 20 in the direction indicated by the arrow. If the flow sensor 25 detects this airflow, the test is successful. In this case, the insertion depth of the inspection tube 21 is then determined by image processing. If the flow sensor 25 does not detect the airflow, the test is unsuccessful. In this case, the flow sensor 25 is adjusted and inspected, and leaks in the flow path are checked. Then, the major leak detection by the flow sensor 25 is performed again, and this process is repeated until the major leak detection by the flow sensor 25 is successful.

[0066] The large leak detection by the flow sensor 25 described above is performed to ensure that the image recognition camera 12 reliably captures leaks from the tip 21a of the inspection tube during the inspection and testing processes described later. In other words, in the inspection and testing processes described later, the image recognition camera 12 captures still images of the bubbles that appear from the tip 21a of the inspection tube at predetermined intervals. Therefore, if the leakage from the tip 21a of the inspection tube is small, the time from the appearance of the bubbles to their surface at the tip 21a of the inspection tube becomes longer. As a result, even if images are taken at intervals of several seconds, the leak can be reliably detected.

[0067] On the other hand, if the leak from the tip 21a of the inspection tube is of a large flow rate (large leak), the time from the appearance of bubbles at the tip 21a of the inspection tube to their rise to the surface becomes shorter. Therefore, when images are taken at intervals of a few seconds, there is a possibility that bubbles will rise to the surface between or at the moment of the image, making it impossible to detect the leak. Thus, when detecting large-flow leaks, image processing of the inspection tube tip 21a is not suitable. Therefore, as a countermeasure, large leak detection using a flow sensor 25 is performed at the preparation stage.

[0068] The insertion depth determination of the inspection tube 21 using image processing is performed to confirm that the linear servo mechanism (operating mechanism) 26 is functioning correctly and that the tip 21a of the inspection tube is in a predetermined position relative to the water in the container 22. This determination is made by moving the inspection tube 21 downward using the operating mechanism 26 from the state shown in Figure 2 and inserting it into the water, and then taking a single photograph of the tip 21a of the inspection tube with the image recognition camera 12.

[0069] If the insertion depth of the inspection tube tip 21a from the water surface is within a predetermined range (when the inspection tube tip 21a is within a predetermined depth), the test is considered successful, and in this case, all judgment items in the preparation process are considered to have been passed, and the preparation process is completed. If the insertion depth is not within the predetermined range, the test is considered unsuccessful, and in this case, the operating mechanism 26 is adjusted so that the inspection tube tip 21a descends to the correct position, and then the insertion depth of the inspection tube 21 is judged again by image processing, and this is repeated until the insertion depth judgment is passed.

[0070] After passing the preparation process before the inspection process described above, the operating mechanism 26 moves the inspection tube 21 upward to open it to the atmosphere. Then, the flow rates of the circuit switching unit 23 and switching valves 30 and 31 shown in Figure 4 are switched to a connected state, and low-pressure air is blown into the inspection tube 21 from the low-pressure air blowing unit 27 to expel the water W adhering to the tip 21a of the inspection tube.

[0071] Next, the inspection process shown in the flowchart in Figure 6 is carried out. In the inspection process, as shown in Figure 3, a dummy valve or test valve 20 is attached to the first branch line 4 with a jig 13 and this valve is opened. The circuit switching section 23 and switching valves 30 and 31 of the air circuit 2 of the inspection device body 1 are switched to configure an inspection circuit 10 in which air moves in the direction of the arrow.

[0072] In the inspection circuit 10, when 0.2 mL / min of air is supplied from the flow standard 3, this air moves in the direction of the arrow. At this time, the inspection process is carried out by determining whether or not bubbles appear from the tip 21a of the inspection tube 21 within the inspection time using the image recognition camera 12.

[0073] In this case, first, the inspection tube 21 is moved downward by the operating mechanism 26 and inserted into the water, thereby immersing the tip 21a of the inspection tube in the water, and in this state, the tip 21a of the inspection tube is photographed by the image recognition camera 12. In this process, the maximum number of shots is denoted as N (times), and the number of shots that increase until this maximum number N is reached is denoted as X (times). This number of shots X is then counted. The maximum number of shots N is determined by the number of shots X equivalent to the set inspection time. In this embodiment, the shooting interval by the image recognition camera is set to every second, and this is repeated a maximum of 30 times (30 seconds). That is, the number of shots X increases every second, and this shooting is repeated until it reaches the maximum number of shots N, which is 30 times. These maximum number of shots N and shooting intervals are set and optimized each time according to the inspection procedure.

[0074] The determination of the change in the captured image at the tip 21a of the inspection tube is performed by recognizing the luminance difference between the bubbles emerging from the tip 21a of the inspection tube and the non-reflective material 29 and the non-reflective paint 32 in the captured image taken by the image recognition camera 12. The flow standard 3 is a so-called pseudo-leak assuming the case where leakage occurs from the test valve 20 in the inspection process. And when the air from this flow standard 3 emerges as bubbles from the tip 21a of the inspection tube, that is, when a change is seen in the captured image, it is regarded as "change exists", and it is recognized that the inspection process described later can be normally carried out, and even at a stage where the number of captures X has not reached the maximum number of captures N (X < N), it is determined that the inspection process is qualified. In this case, the tip 21a side is made to communicate with the atmosphere by a step of moving the inspection tube 21 upward by the operation mechanism part 26, retreating its tip 21a from the water, and opening the inspection tube 21 to the atmosphere.

[0075] After the atmosphere opening step, the circuit switching part 23, the switching valves 30, 31 of the air circuit 2 of the inspection apparatus main body 1 are switched to the state shown in FIG. 4, and ultra-low pressure air of 0.1 MPa or less is blown into the inspection tube 21 from the low-pressure air blowing part 27 for 1 second or less as shown by the arrow, so as to discharge the water W adhering to the tip 21a of the inspection tube. Thereby, after the inspection tube 21 is lifted, the water droplets adhering to its tip 21a and the internal water W are removed to make it a clean state, and it is prevented that the water droplets are sucked into the inspection tube 21. As a result, in subsequent processes, there is no possibility that the occurrence of leakage from the tip 21a of the inspection tube due to the remaining water droplets is delayed.

[0076] On the other hand, when no bubbles emerge from the tip 21a of the inspection tube, that is, when no change is seen in the captured image, it is regarded as "no change", and the confirmation of the number of captures X proceeds. And if this number of captures X has not reached the maximum number of captures N, assuming X < N, the capturing is repeated in the same manner.

[0077] Upon checking the number of shots X, if this number of shots X reaches the same value as the maximum number of shots N (number of shots X = maximum number of shots N), the inspection device body 1 is deemed to be in an abnormal state where it cannot produce bubbles from the tip 21a of the inspection tube within a predetermined time, and the inspection process is judged to have failed.

[0078] If the inspection process fails, it means that the flow rate of the flow standard 3 does not appear as bubbles or cannot be confirmed. After determining that the system has failed, the countermeasures and checks should be made to check, for example, whether there is any blockage such as oil in the air circuit 2, whether there are any holes or damage in the air circuit 2, whether the test valve 20 is properly clamped by the jig 13 (whether there is any gap between the flow path of the test valve 20 and the jig 13), whether the image recognition camera 12 is working properly, and whether there are any malfunctions in the circuit switching unit 23 or the switching valves 30 and 31. Appropriate countermeasures should be taken according to the results. After implementing countermeasures and checks, the inspection process will be repeated starting from the first time the images were taken. Only if the inspection process is deemed satisfactory will the preparation and inspection processes proceed.

[0079] Figure 9 shows a flowchart of the preparation process before the inspection process. This preparation process, similar to the process before the inspection process, includes at least the water level determination by image processing of the image recognition camera 12, the water level determination by the weight sensor 24, the detection of major leaks by the flow sensor 25, and the determination of the insertion depth of the inspection tube 21 by image processing of the image recognition camera 12. Similar to the preparation process, any or all of these determinations may be performed, and in this embodiment, all of these determinations are performed sequentially.

[0080] In the preparation process before the inspection process, the water level determination by image processing, the water level determination by the weight sensor 24, and the determination of the insertion depth of the inspection tube 21 by image processing are performed in the same manner as in the preparation process before the inspection process. For the detection of major leaks by the flow sensor 25, only the processing after failure differs from that in the preparation process before the inspection process.

[0081] If the flow sensor 25 determines that a major leak has occurred during the preparation process before the inspection process, it is assumed that a major leak has occurred from the test valve 20, and this test valve 20 is deemed to have failed the valve seat inspection test. In this case, it becomes possible to inspect a different test valve 20 without proceeding to the inspection process.

[0082] If all the criteria for water level determination by image processing, water level determination by weight sensor 24, major leak detection by flow sensor 25, and insertion depth of inspection tube 21 by image processing are met, the preparation process is considered to have been completed.

[0083] After passing the preparation process, the operating mechanism 26 moves the inspection tube 21 upward to open it to the atmosphere. Then, the flow rates of the circuit switching unit 23 and switching valves 30 and 31 shown in Figure 4 are switched to a connected state, and low-pressure air is blown into the inspection tube 21 from the low-pressure air blowing unit 27 to expel the water W adhering to the tip 21a of the inspection tube, after which the inspection process is performed.

[0084] The flowchart shown in Figure 7 illustrates the process from start to finish. In the inspection process, if a dummy valve was installed in the inspection process as shown in Figure 5, it is removed, and the test valve 20, which has pressure sealed inside its cavity and is in a closed state, is attached to the first branch line 4 of the air circuit 2 using a jig 13. Then, the circuit switching section 23, switching valves 30 and 31 of the air circuit 2 of the inspection device body 1 are switched to configure the inspection circuit 11 so that air moves in the direction of the arrow.

[0085] In the inspection circuit 11, air leaking from the valve seat side of the test valve 20 in the closed state proceeds from both sides through the jig 13 in the direction of the arrow. At this time, the inspection process is carried out by determining whether or not bubbles appear from the tip 21a of the inspection tube within the inspection time using the image recognition camera 12.

[0086] In this case, similar to the inspection process, the tip 21a of the inspection tube is inserted into the water, and with this in place, the image camera 12 is triggered to take a picture of the tip 21a of the inspection tube, with X being the number of shots and N being the maximum number of shots. As in the inspection process, the number of shots X increases every second, and the shooting is repeated until the maximum number of shots N, which is 30 (30 seconds), is reached.

[0087] Leak detection from the tip 21a of the inspection tube is performed in the same way as in the inspection process, by recognizing the difference in brightness between the bubbles that appear from the tip 21a of the inspection tube and the anti-reflective material 29 or anti-reflective paint 32. If no bubbles appear from the tip 21a of the inspection tube during the leak detection, i.e., no leak is detected, it is determined to be "no leak," and the same imaging is repeated. When the number of imaging counts X is confirmed, if this number of imaging counts X is equal to the maximum number of imaging counts N (number of imaging counts X = maximum number of imaging counts N), it is determined that no valve seat leak was detected within the predetermined inspection time, and the inspection process is deemed to have passed.

[0088] On the other hand, if bubbles appear from the tip 21a of the inspection tube, i.e., if leakage is detected, it is determined that "leakage is present," and even if the number of images taken X is less than the maximum number of images taken N (number of images taken X < maximum number of images taken N), it is determined that valve seat leakage occurred in less than the predetermined inspection time, and the inspection process is deemed to have failed. In this case, the test valve 20 becomes a failed product in the valve seat inspection.

[0089] In either case of passing or failing the valve seat inspection, the operating mechanism 26 moves the inspection tube 21 upward, retracting its tip 21a from the water and opening it to the atmosphere.

[0090] After opening to the atmosphere, the circuit switching section 23 and switching valves 30 and 31 of the air circuit 2 of the inspection device body 1 are switched to the state shown in Figure 4, and ultra-low pressure air of 0.1 MPa or less is blown from the low-pressure air blowing section 27 into the inspection tube 21 for less than 1 second to expel the water W adhering to the tip 21a of the inspection tube. This removes water droplets and internal water W adhering to the tip 21a of the inspection tube, prevents water droplets from being sucked into the inspection tube 21, and eliminates the risk of residual water droplets delaying the occurrence of leakage from the tip 21a of the inspection tube when inspecting another test valve 20.

[0091] After inspecting the valve seat of one test valve 20, it is possible to proceed with inspecting the valve seat of a different test valve 20. In this case, as mentioned above, by performing the inspection process only once before the inspection process, it becomes possible to repeatedly perform the inspection process after the inspection process has been completed.

[0092] In the above embodiment, a ball valve is used as the test valve 20, but it is also possible to perform valve seat inspection in the same manner as above using a valve other than a ball valve as the test valve. When a ball valve is used as the test valve 20, the pass / fail determination is made by detecting valve seat leakage from both sides while pressure is sealed inside the cavity, but it is also possible to apply a predetermined pressure for inspection from the primary side of the test valve 20 in a closed state and determine the pass / fail status by valve seat leakage from the secondary side.

[0093] Furthermore, although the inspection time is set to 30 seconds (30 shots), this inspection time can be appropriately changed depending on the length of the air passage 2 of the inspection device body 1. Therefore, it is possible to shorten the air circuit 2 and reduce the time required for the preparation, inspection, and testing processes. Furthermore, the imaging interval may be shortened or lengthened as appropriate, depending on the speed at which bubbles appear from the tip 21a of the inspection tube at the standard leak rate, and the inner diameter of the inspection tube 21.

[0094] The valve seat inspection method using an image recognition camera of the present invention involves an inspection device body 1 having an inspection circuit 10, an inspection circuit 11, and an image recognition camera 12. By switching the circuit switching unit 23, the device undergoes an inspection process and an inspection process. In both the inspection and inspection processes, the image recognition camera 12 determines whether a very small amount of bubbles appear from the tip 21a of the inspection tube within 30 seconds. This eliminates the need for a high-precision flow sensor to measure minute flow rates. A simple, general-purpose image recognition camera 12, such as an industrial camera, can be used to easily and accurately detect even minute leaks that cannot be detected by general-purpose flow sensors. This simple inspection device body 1 allows for continuous and accurate valve seat inspection through automation. There is no need to visually inspect bubbles from the tip 21a of the inspection tube or measure the size of the bubbles with the image recognition camera 12. Only the appearance of bubbles within a predetermined inspection time needs to be detected, making the inspection easy and convenient.

[0095] As described above, since it becomes possible to achieve inspection accuracy equivalent to that of visually inspecting the valve seat using the image recognition camera 12, it becomes possible to provide valve seat inspection methods and valve seat inspection devices in accordance with the standards set forth in the API (American Petroleum Institute) "Valve Inspection and Testing".

[0096] This standard acknowledges that visually detectable leaks can be replaced by measuring instruments, and for this purpose, the "Volimetric Device" is specified. The "Volimetric Device" is designed to visually measure the number of bubbles per unit time (bubbles / min).

[0097] In contrast, the inspection device body 1 of the present invention performs an inspection process and an inspection process, and in each process, it uses an image recognition camera 12 to check whether or not bubbles appear during the inspection time and determines whether it is a pass or fail, thereby improving the accuracy of valve seat leak inspection.

[0098] Furthermore, in each step, the operating mechanism 26 controls the steps of inserting the tip 21a of the inspection tube into the water and releasing it to the atmosphere. Unlike the measuring instrument described above, where the tube is always inserted, the inspection tube is not constantly affected by atmospheric pressure. Therefore, it is possible to generate bubbles from the inspection tube 21 using air from the air circuit 2 with an accurate flow rate while minimizing the influence of atmospheric pressure. By attaching and detaching the test valve 20 while the inspection tube 21 is released to the atmosphere, pressure changes within the air circuit 2 caused by this attachment and detachment are also prevented.

[0099] Furthermore, as a preliminary step to the inspection and testing processes, the system performs water level determination using image processing, water level determination using a weight sensor 24, major leak detection using a flow sensor 25, and determination of the insertion depth of the inspection tube 21 using image processing. This allows for confirmation of whether the inspection device body 1 is functioning correctly before the inspection and testing processes, thereby improving the accuracy of these inspection and testing processes.

[0100] Figure 10 shows another embodiment of the valve seat inspection device. In this embodiment, the same parts as in the previous embodiment are denoted by the same reference numerals, and their descriptions are omitted. In this embodiment, the inspection device body 40 applies a predetermined inspection pressure to the primary side of the test valve 41 in a closed state, and determines whether it passes or fails based on the valve seat leakage that occurs from the secondary side due to this inspection pressure.

[0101] On the primary side of the air circuit 42 that constitutes the inspection device body 40, an inspection pressure supply path 43 and an inspection pressure supply path 44 are provided via a circuit switching unit 23, and the flow paths of these inspection pressure supply paths 43 and 44 are switchable by the circuit switching unit 23. The inspection device body 40 is configured to be able to configure either an inspection circuit 45 or an inspection circuit 46 by switching the circuit switching unit 23. In this embodiment, the switching states of the flow paths of the circuit switching unit 23 and the switching valves 30 and 31 are not shown.

[0102] The inspection circuit 45 is configured by switching the circuit switching unit 23 so that the flow standard 3 provided on the primary side of the inspection pressure supply path 43 is in communication with the test valve 41 side. This inspection circuit 45 allows for the inspection of the reference leak amount in the flow path indicated by the dashed arrow. The inspection circuit 46 is configured by switching the circuit switching unit 23 so that the inspection pressure supply unit 47, which is provided on the primary side of the inspection pressure supply path 44, is in communication with the valve under test 41. Switching this inspection circuit 46 makes it possible to inspect the valve seat leakage of the valve under test in the flow path indicated by the dashed arrow.

[0103] Immediately after the circuit switching section 23, a jig 13 made of a clamping member is provided, and the test valve 41 is connected to this jig 13. The inspection device body 40 is designed to clamp both ends of the test valve 41 with the jig 13, pressurize the test valve 41 from the primary side when it is in a closed state, and use the image recognition camera 12 to determine whether the valve seat leaks out from the secondary side and whether it passes or fails.

[0104] The test valve 41 is, for example, a ball valve, and is particularly suitable for inspecting the valve seat of a relatively large ball valve.

[0105] When performing the preparation process using the inspection device body 40 described above, the water level determination by image processing of the image recognition camera 12, the water level determination by the weight sensor 24, the large leak detection by the flow sensor 25, and the insertion depth determination of the inspection tube 21 by image processing of the image recognition camera 12 are performed before the inspection process and before the test process, respectively, as described above.

[0106] Next, when performing the inspection process, the circuit switching unit 23 is switched so that the inspection pressure supply path 43 is connected to the inspection tube 21 through the test valve 41, thereby configuring the inspection circuit 45, and the inspection is carried out in the same manner as described above. Furthermore, when performing the inspection process, the circuit switching unit 23 is switched so that the inspection pressure supply path 44 is connected to the inspection tube 21 through the test valve 41, thereby configuring the inspection circuit 46, and the inspection is performed in the same manner as described above. By going through these inspection and testing processes, the valve seat inspection of the test valve 41 using the inspection device body 40 is completed, and it is possible to accurately determine whether the test valve 41 is pass or fail. Furthermore, it becomes possible to perform valve seat inspections of different test valves 41 in the same manner.

[0107] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the embodiments described above, and various modifications can be made without departing from the spirit of the invention as described in the claims of the present invention. [Explanation of Symbols]

[0108] 1. Inspection device main unit 1a Inner wall 10. Inspection Circuit 11 Test Circuit 20 Test valve 21 Test tube 22 Container 21a Tip 12 Image recognition camera 23 Circuit switching section 24 Weight Sensors 25 Flow Sensor 26 Linear servo mechanism (operating mechanism) 27 Low-pressure air blowing section 32 Non-reflective paint W water

Claims

1. A valve seat inspection method using an image recognition camera, comprising: an inspection device main body having an inspection circuit that checks for leakage of a standard leak amount, an inspection circuit with a test valve installed, and an image recognition camera that inserts an inspection tube connected to the inspection circuit into water in a container and photographs bubbles that appear from the tip of the inspection tube, wherein the inspection device main body undergoes an inspection process in which a circuit switching unit that switches between the inspection circuit and the inspection circuit is switched to determine whether or not bubbles appear from the tip of the inspection tube within an inspection time using the image recognition camera, and an inspection process in which the circuit switching unit is switched to determine whether or not bubbles appear from the tip of the inspection tube within the inspection time using the image recognition camera,

2. 2. A valve seat inspection method using an image recognition camera as described in claim 1, wherein as a preliminary process to the inspection process, at least any or all of the following are performed: water level determination by image processing, water level determination by a weight sensor, large leak determination by a flow sensor, and determination of the insertion depth of the inspection tube by image processing.

3. 3. The valve seat inspection method using an image recognition camera according to claim 1 or 2, further comprising blowing low pressure air into the inspection tube to expel water adhering to the tip of the inspection tube.

4. 4. The valve seat inspection method using an image recognition camera according to claim 1, wherein the step of inserting the tip of the inspection tube into water and the step of opening to the atmosphere are performed by an operating mechanism.

5. 5. The valve seat inspection method using an image recognition camera according to claim 1, wherein the inspection device body and its inner wall are painted with anti-reflective paint that prevents reflection of light, thereby obtaining the detection performance of the image recognition camera.

6. A valve seat inspection device using an image recognition camera, comprising: an inspection circuit for inspecting for leakage of a standard leak amount; the inspection circuit with a test valve installed; an image recognition camera for photographing bubbles appearing from the tip of an inspection tube connected to the inspection circuit when the inspection tube is inserted into a container filled with water; a circuit switching unit for switching between the inspection circuit and the inspection circuit; and an operating mechanism unit for inserting the inspection tube into water and opening it to the atmosphere.

7. 7. A valve seat inspection device using an image recognition camera as described in claim 6, wherein the image recognition camera is configured to determine at least leakage based on the presence or absence of bubbles appearing from the tip of the inspection tube, determine the water level in the container, and determine the insertion depth of the inspection tube.

8. 8. The valve seat inspection device using an image recognition camera according to claim 6 or 7, wherein the operation mechanism is a linear servo mechanism that moves up and down.

9. 9. The valve seat inspection device using an image recognition camera according to claim 6, wherein the inspection tube is provided with a low pressure air blowing section so as to expel water adhering to the tip of the inspection tube.

Images