JP6767076B2 - Magnetic particle inspection device and magnetic particle inspection method - Google Patents

Description

The present invention relates to a flaw detection device and a flaw detection method, and more specifically, to a magnetic particle flaw detector that performs flaw detection using magnetic powder, and a magnetic powder flaw detection method.

The magnetic particle flaw detection test is applied to a flaw detection inspection of the surface of a steel material such as a billet or an object to be inspected such as an automobile shaft, and is standardized in JIS-Z-2320. In the magnetic particle inspection test, a magnetic powder liquid containing magnetic powder is sprayed on the surface of the object to be inspected, and a magnetic field is applied to the object to be inspected to magnetize the object to be inspected. When there is a scratch such as a crack on the surface of the magnetized object to be inspected, the magnetic flux leaks from the scratch, so that the magnetic powder is attracted to the leaked magnetic flux and an instruction pattern by the magnetic powder is formed. Then, the scratch is inspected by observing this magnetic particle instruction pattern. Various forms of such a magnetic particle inspection have been proposed in order to improve the detection accuracy. For example, a fluorescent magnetic particle inspection using a fluorescent magnetic powder whose surface is coated with a phosphor is known.

Further, in Patent Document 1, in the magnetic particle inspection method for a metal material, after the magnetic powder liquid is sprayed while magnetizing the material to be inspected, water is sprinkled on the surface of the material to be inspected in a state where the magnetization force is increased from the time when the magnetic powder liquid is sprayed. A method for forming a magnetic powder pattern in magnetic particle inspection is disclosed, which comprises washing away excess magnetic powder liquid excluding the magnetic powder pattern on the surface flaw portion of the material to be inspected.

Further, in Patent Document 2, after spraying a magnetic particle liquid from a spray nozzle on a flaw-detected material, a magnetic particle flaw detection test is performed to detect defects of the flaw-detected material by detecting magnetic powder aggregated and adsorbed on a defective portion of the flaw-detected material. At this time, a magnetic particle flaw detection test method is disclosed, which comprises spraying a magnetic particle liquid from a spray nozzle toward a material to be detected and then spraying water from the same spray nozzle.

Further, Patent Document 3 discloses a long-term dispersibility test of a magnetic powder liquid using a test device including a SUS tank and a pump and circulating the magnetic powder liquid through a pipe.

JP-A-5-288718 JP-A-7-333196 Japanese Patent No. 2775401

According to the magnetic particle pattern forming method of Patent Document 1 and the magnetic particle flaw detection test method of Patent Document 2, it is possible to remove excess magnetic powder adhering to the surface of the object to be inspected by spraying water after spraying the magnetic powder liquid. It is said that false detection of scratches can be prevented.

Here, a large amount of magnetic particle liquid is often used in the magnetic particle inspection, and from the viewpoint of reducing the burden on the environment and the disposal cost, the magnetic particle liquid sprayed on the object to be inspected is collected and reused. It is preferable to do so. As a physical property test of the magnetic powder liquid when the magnetic powder liquid is recycled, a long-term dispersibility test of the magnetic powder liquid of Patent Document 3 and the like are known. However, when water is sprayed after spraying the magnetic powder liquid as in the magnetic powder pattern forming method of Patent Document 1 and the magnetic particle flaw detection test method of Patent Document 2, the sprayed water is mixed in the recovered magnetic powder liquid. Since the magnetic particle concentration decreases, there is a problem that if the recovered liquid is reused as it is, the detection accuracy of the scratched portion decreases. Further, in Patent Document 1 and Patent Document 2, no consideration is given to the recovery and reuse of the magnetic powder liquid.

Therefore, an object of the present invention is a magnetic particle flaw detection device and a magnetic particle flaw detection method, which can reuse the test solution with a simple structure, have high scratch detection accuracy, and maintain the scratch detection accuracy at a certain level or higher. Is to provide.

In order to solve the above problems, the magnetic particle flaw detector of the present invention
A test liquid tank that stores the test liquid containing magnetic powder,
The magnetized part that magnetizes the object to be inspected and
A spraying portion for spraying the test solution on the object to be inspected,
A cleaning unit that sprays the test solution onto the object to be inspected,
It is provided with a test solution collecting section for collecting the test solution sprayed by the spraying section and the cleaning section and returning the test solution to the test solution tank.
The test liquid tank is
With a bottomed tubular tank body
A partition wall having a gap between the bottom wall of the tank body and partitioning the inside of the tank body into a stirring tank for storing the test solution in a stirred state and a settling tank for storing the test solution in a stationary state. Have and
The spraying portion is connected to the stirring tank, and the cleaning portion is connected to the upper part of the settling tank.

Further, the bottom surface of the settling tank is characterized in that it is inclined downward toward the stirring tank.

Further, the spraying portion has a circulation circuit in which the stirring tank, the spraying pump, and the switching valve to which the spraying nozzle is branched and connected are circulated and connected by piping.
The pipe is characterized in that it is connected to the stirring tank so that the test liquid in the stirring tank flows in a spiral shape by the test liquid discharged to the stirring tank.

Further, the test liquid recovery unit is
The collection receiver placed below the object to be inspected,
One end has a collection pipe connected to the collection receiver, and the other end has a collection pipe connected to the test liquid tank.
The other end of the recovery pipe is connected to the lower part of the settling tank so as to face the stirring tank.

Further, the recovery pipe is provided with a recovery magnetic powder magnetizing portion for applying a magnetic field.

Further, it is characterized in that the settling tank magnetic powder magnetizing portion for applying a magnetic field is provided in the settling tank.

Further, a level sensor for measuring the liquid level of the test liquid in the test liquid tank and a level sensor
A magnetic particle concentration measuring device for measuring the magnetic particle concentration of the test solution in the stirring tank, and
A concentrated magnetic powder liquid supply device that supplies a concentrated magnetic powder liquid having a concentration higher than the magnetic powder concentration of the inspection liquid in the stirring tank to the stirring tank.
It is characterized by including a liquid supply device that supplies only the solvent of the test liquid to the settling tank.

Further, the tank main body is configured by being divided into the stirring tank and the settling tank by the partition wall, and further has a communication pipe that communicates the bottom of the stirring tank with the bottom of the settling tank.

Further, the present invention relates to a magnetic particle flaw detection method for detecting an object to be inspected by using an inspection liquid containing magnetic powder stored in an inspection liquid tank.
The test liquid tank is
With a bottomed tubular tank body
A partition wall having a gap between the bottom wall of the tank body and partitioning the inside of the tank body into a stirring tank for storing the test solution in a stirred state and a settling tank for storing the test solution in a stationary state. Have and
The step of magnetizing the object to be inspected and
A step of spraying the test solution in the stirring tank onto the object to be inspected,
A step of spraying the test solution on the upper part of the settling tank onto the object to be inspected,
It is characterized by comprising a step of collecting the test liquid sprayed on the test object and returning it to the test liquid tank.

According to the present invention, the inspection liquid tank for storing the inspection liquid containing magnetic powder, the magnetizing portion for magnetizing the inspection object, the spraying portion for spraying the inspection liquid on the inspection object, and the inspection object. The test liquid tank is provided with a cleaning unit for spraying the test liquid, a spraying unit, and a test liquid recovery unit for collecting the test liquid sprayed by the cleaning unit and returning the test liquid to the test liquid tank. Precipitation that has a gap between the tubular tank body and the bottom wall of the tank body and stores the test solution in a stirred state and the test solution in a stationary state inside the tank body. Since it has a partition partition partitioning from the tank, the spraying portion is connected to the stirring tank, and the cleaning portion is connected to the upper part of the settling tank, the test solution can be reused with a simple configuration and scratches. It is possible to provide a magnetic particle flaw detector that has high detection accuracy of a portion and maintains the detection accuracy of a scratch portion at a certain level or higher.

Further, since the bottom surface of the settling tank is inclined downward toward the stirring tank, the magnetic powder settled in the settling tank moves to the stirring tank, and the magnetic powder concentration of the inspection liquid in the stirring tank is unlikely to decrease, so that the wound portion is damaged. The detection accuracy can be more reliably maintained above a certain level.

Further, the spraying portion has a circulation circuit in which the stirring tank, the spraying pump, and the switching valve to which the spray nozzle is branched and connected are circulated and connected by a pipe, and the pipe is discharged to the stirring tank. Since the test solution in the stirring tank is connected to the stirring tank so as to flow in a spiral shape by the test solution, the test solution in the stirring tank can be stirred with a simple structure without using a separate stirrer or the like. , Productivity is improved. In addition, the spraying portion can instantly spray the inspection liquid in which the magnetic powder is dispersed, so that the flaw detection time can be shortened.

Further, the test liquid recovery unit has a recovery receiver arranged below the object to be inspected, and a recovery pipe having one end connected to the recovery receiver and the other end connected to the test liquid tank. Since the other end of the recovery pipe is connected to the lower part of the settling tank so as to face the stirring tank, the recovered test solution having a low magnetic powder concentration is returned to the settling tank, and the test solution having a high magnetic powder concentration is sent to the stirring tank. The magnetic powder concentration of the test solution in the stirring tank is less likely to decrease, and the detection accuracy of the scratched portion can be more reliably maintained at a certain level or higher.

Further, since the recovery magnetic powder magnetizing portion for applying a magnetic field is provided in the recovery pipe, the magnetic powder can be bonded to increase the settling speed of the magnetic powder, and when the particle size of the magnetic powder is small or the capacity of the settling tank is small. Even if there is, the detection accuracy of the scratched portion can be increased.

Further, since the settling tank magnetic powder magnetized portion for applying a magnetic field is provided in the settling tank, the magnetic powder can be combined to increase the settling speed of the magnetic powder, and when the particle size of the magnetic powder is small or the capacity of the settling tank is small. Even so, the detection accuracy of the scratched portion can be increased.

Further, a level sensor for measuring the liquid level of the test liquid in the test liquid tank, a magnetic powder concentration measuring device for measuring the magnetic powder concentration of the test liquid in the stirring tank, and magnetic powder of the test liquid in the stirring tank. Since it is provided with a concentrated magnetic powder liquid supply device that supplies a concentrated magnetic powder liquid having a concentration higher than the concentration to the stirring tank and a liquid supply device that supplies only the solvent of the test liquid to the settling tank, the test liquid in the stirring tank The magnetic powder concentration and the amount of liquid can be kept constant, and the detection accuracy of the scratched portion can be more reliably maintained above a certain level.

Further, the chemical solution tank main body is configured by being divided into the stirring tank and the settling tank by the partition wall, and further has a communication pipe that communicates the bottom of the stirring tank with the bottom of the settling tank, so that the structure is simple. It is possible to provide a magnetic particle flaw detector that can reuse the test solution, has a high scratch detection accuracy, and maintains the scratch detection accuracy at a certain level or higher.

Further, according to the present invention, in the magnetic particle inspection method of detecting an object to be inspected by using an inspection liquid containing magnetic powder stored in the inspection liquid tank, the inspection liquid tank has a bottomed tubular tank body. A partition wall having a gap between the bottom wall of the tank body and partitioning the inside of the tank body into a stirring tank for storing the test solution in a stirred state and a settling tank for storing the test solution in a stationary state. The step of magnetizing the object to be inspected, the step of spraying the test solution in the stirring tank on the object to be inspected, and the step of spraying the test solution on the upper part of the settling tank on the object to be inspected. Since the step of collecting the test solution sprayed on the object to be inspected and returning the test solution to the test solution tank is provided, the test solution can be reused with a simple configuration and the detection accuracy of the scratched portion is high. It is possible to provide a magnetic particle flaw detection method that maintains a constant value.

It is a schematic block diagram which showed an example of the magnetic particle inspection apparatus which concerns on this embodiment. It is a schematic block diagram which showed the spraying part, the cleaning part, and the test liquid recovery part. It is a schematic diagram which showed the test liquid tank. It is a block diagram of the control system of a magnetic particle flaw detector. It is a schematic block diagram which showed the spraying part, the cleaning part, and the test liquid recovery part which concerns on another embodiment. It is a schematic block diagram which showed the magnetic particle inspection apparatus which concerns on another embodiment. It is a flow chart which showed the outline of the magnetic particle inspection method which concerns on this embodiment. It is a flow chart which showed the outline of the magnetic particle concentration adjustment process. It is a time chart which shows the operation of a magnetizing part, a spraying part, and a cleaning part.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic configuration diagram showing an example of a magnetic particle flaw detector 1 according to the present embodiment, and FIG. 2 is a schematic configuration diagram showing a spraying unit 13, a cleaning unit 14, and an inspection liquid collecting unit 15. , FIG. 3 is a schematic view showing the test liquid tank 11. In the following, for convenience of explanation, in FIG. 1, the side of the imaging unit 17 described later is on the top, and the side of the test solution collecting unit 15 described later is on the bottom. Further, in FIG. 1, the description of the test liquid tank 11 and the like is omitted. Further, in FIG. 2, the flow direction of the test liquid is indicated by an arrow d1, and the description of the magnetizing unit 12, which will be described later, the ultraviolet irradiation unit 16, the imaging unit 17, etc., which will be described later, is omitted. Further, FIG. 3 is a schematic view of the test liquid tank 11 as viewed from above, and the flow direction of the test liquid is indicated by an arrow d2.

As shown in FIGS. 1 to 3, the magnetic particle flaw detector 1 detects, for example, a scratched portion as a defect on the surface (outer peripheral surface) of the object 10 to be inspected, which is a columnar shaft, using magnetic powder. It is composed. The magnetic particle inspection device 1 includes an inspection liquid tank 11, a magnetizing unit 12, a spraying unit 13, a cleaning unit 14, an inspection liquid collecting unit 15, an ultraviolet irradiation unit 16, an imaging unit 17, and a control unit (not shown). And a detection unit (not shown) is provided. Then, the magnetic particle flaw detector 1 magnetizes the object 10 to be inspected by the magnetizing portion 12, and sprays the inspection liquid containing magnetic powder on the object 10 to be inspected by the spraying portion 13 to form a magnetic particle instruction pattern on the scratched portion. While the inspection object 10 is kept magnetized, the cleaning unit 14 sprays the inspection liquid on the inspection object 10 to remove excess magnetic powder adhering to the surface of the inspection object 10, and the imaging unit 17 removes the excess magnetic powder. 10 is imaged, and the scratched portion is detected based on the image captured by the detection unit. Further, the magnetic particle inspection device 1 is configured to collect and reuse the inspection liquid sprayed on the object to be inspected 10 by the spraying unit 13 and the cleaning unit 14 by the inspection liquid collecting unit 15. The magnetic particle flaw detector 1 also includes a support portion (not shown) that supports the object 10 to be inspected.

As shown in FIGS. 2 and 3, the inspection liquid tank 11 for storing the inspection liquid used in the magnetic particle flaw detector 1 has a stirring tank 20 and a settling tank 21. The bottom of the settling tank 21 communicates with the bottom of the stirring tank 20. More specifically, the test liquid tank 11 has a bottomed tubular tank body 22 and a flat plate-shaped partition wall 23 extending in the vertical direction. The tank body 22 has a cylindrical side wall 24 and a bottom wall 25 whose upper side is connected to the lower side of the side wall 24. The bottom wall 25 has a tubular reduced diameter portion 25a of a substantially inverted truncated cone whose upper portion is connected below the side wall 24 and whose diameter is reduced from upper to lower, and a flat bottom end portion which is connected below the reduced diameter portion 25a. It has 25b and. The partition wall 23 extends from one side of the inner peripheral surface of the side wall 24 of the tank body 22 to the other side, and partitions the inside of the tank body 22 into a stirring tank 20 and a settling tank 21. The lower end of the partition wall 23 is not connected to the bottom wall 25, and a gap is formed between the partition wall 23 and the bottom wall 25. The bottom of the settling tank 21 communicates with the bottom of the stirring tank 20 through this gap. Therefore, the test solution stored in the stirring tank 20 can be moved from the bottom to the settling tank 21, and the test solution stored in the settling tank 21 can be moved from the bottom to the stirring tank 20.

The partition wall 23 is arranged so as to be offset from the axial center of the side wall 24 so that the volume of the stirring tank 20 is larger than the volume of the settling tank 21, and does not cross the bottom end portion 25b of the bottom wall 25 in a plan view. It is arranged like this. The bottom surface of the settling tank 21 is a reduced diameter portion 25a of the bottom wall 25 and is inclined downward toward the stirring tank 20. The partition wall 23 prevents the test liquid from moving between the stirring tank 20 and the settling tank 21.

The test solution stored in the test solution tank 11 is a solution obtained by mixing magnetic powder with water as a solvent. The magnetic powder is a powder of a magnetic material such as iron oxide, the surface of which is coated with a fluorescent material, and the median diameter is about 3 μm to 70 μm. The magnetic powder contained in the test solution may have a structure in which the surface thereof is not coated with a phosphor. Further, the solvent of the test solution may be white kerosene. Further, the test solution may be configured to further contain a dispersant, a rust preventive, and the like. As the dispersant, for example, a polyoxyalkylene allyl phenyl ether type nonionic surfactant and an anionic activator can be used. As the rust preventive, for example, sodium nitrite or the like can be used. In addition, the concentration of magnetic powder, dispersant, rust preventive, etc. in the test solution can be appropriately set.

Although the details will be described later, the test solution is stored in the stirring tank 20 in a stirred state in which the magnetic powder is dispersed. On the other hand, the test solution is stored in the settling tank 21 in a stationary state in which the magnetic powder settles. Therefore, the inspection liquid in the upper part of the settling tank 21, that is, the supernatant contains almost no magnetic powder. Here, the inspection solution in a state where almost no magnetic powder is contained is an inspection solution having a magnetic powder concentration of 50% or less of the magnetic powder concentration of the inspection solution of the stirring tank 20, and more preferably 20% or less. Is.

The test liquid tank 11 is made of a material that does not affect the physical properties of the stored test liquid. As the material of the test liquid tank 11, for example, stainless steel, aluminum, copper, synthetic resin and the like can be used. The material of the test liquid tank 11 is preferably a non-ferromagnetic material. Further, the tank body 22 and the partition wall 23 may be formed of different materials, and may be subjected to surface treatment such as plating as a rust preventive treatment.

The test liquid tank 11 is not limited to the above configuration. The test liquid tank 11 has a gap between the bottomed tubular tank body 22 and the bottom wall 25 of the tank body 22, and has a stirring tank 20 that stores the test liquid in a stirred state inside the tank body 22. Any configuration may be used as long as it has a partition wall 23 that separates the settling tank 21 that stores the test liquid in a stationary state. For example, a part of the lower end of the partition wall 23 may be connected to the bottom wall 25. Further, the partition wall 23 may be curved toward the settling tank 21 in a plan view. Further, the test liquid tank 11 may be further provided with a lid portion that closes the opening of the tank body 22. With such a configuration, it is possible to prevent foreign substances such as dust and dirt from being mixed into the test solution. Further, the tank body 22 may be formed in the shape of a bottomed polygonal cylinder or a bottomed elliptical cylinder. Further, the bottom wall 25 of the tank body 22 may be formed flat without having a reduced diameter portion 25a. However, it is preferable that the bottom wall 25 has a reduced diameter portion 25a as described above, and the bottom surface of the settling tank 21 is formed so as to incline downward toward the stirring tank 20. With such a configuration, the magnetic powder precipitated in the settling tank 21 can be moved to the stirring tank 20 by gravity, and a decrease in the magnetic powder concentration of the test solution in the stirring tank 20 can be easily prevented. The same effect can be obtained if the bottom surface of the stirring tank 20 is located below the bottom surface of the settling tank 21, for example, the bottom surface of the settling tank 21 and the bottom surface of the stirring tank 20 form a step. It may be connected to.

The partition wall 23 may be any as long as it prevents the test liquid from moving between the stirring tank 20 and the settling tank 21, and is not limited to the above-mentioned one plate-shaped member. For example, the partition wall 23 may be configured to divide the tank body 22 into a stirring tank 20 and a settling tank 21. At this time, the tank body 22 further has a communication pipe that communicates the bottom of the stirring tank 20 with the bottom of the settling tank 21. The test liquid tank 11 having such a configuration includes a bottomed tubular tank as the stirring tank 20, another bottomed tubular tank as the settling tank 21, and a communication pipe that communicates the bottoms of the two tanks. The configuration having the above can be exemplified. It is preferable that the communication pipe is configured so as to incline downward from another tank as the settling tank 21 toward the tank as the stirring tank 20 and to shorten the length thereof.

The test liquid tank 11 has a gap between the bottomed tubular tank body 22 and the bottom wall 25 of the tank body 22 to partition the inside of the tank body 22 into a stirring tank 20 and a settling tank 21. It is configured to include a partition wall 23. Therefore, the stirring tank 20 and the settling tank 21 can be formed with a simple structure, and the productivity is good. Further, in the test liquid tank 11, when there is an existing bottomed tubular tank as the stirring tank 20, the bottom of another new tank as the settling tank 21 is connected to the existing bottom of the tank as the stirring tank 20 by a communication pipe. It can also be configured to communicate with the bottom of a bottomed tubular tank, resulting in good productivity.

The magnetizing portion 12 is configured to apply a magnetic field to the object to be inspected 10 to magnetize at least the surface layer portion of the object to be inspected 10. More specifically, the magnetizing portion 12 is configured to magnetize the surface layer portion of the object 10 to be inspected by using an energization method and a coil method. As shown in FIG. 1, the magnetized portions 12 include electrodes 26 and 27 that come into contact with both ends of the object 10 to be inspected and allow an electric current to flow through the object 10 to be inspected, and an exciting coil 28 arranged near both ends of the object 10 to be inspected. , 29, etc. are provided. The object to be inspected 10 is inserted through the exciting coils 28 and 29.

The magnetized portion 12 forms a magnetic field in a direction (circumferential direction) orthogonal to the axial direction of the object to be inspected 10 by passing an electric current through the electrodes 26 and 27 to the object to be inspected 10. Further, the magnetizing portion 12 forms a magnetic field in the axial direction of the object to be inspected 10 by flowing an electric current through the exciting coils 28 and 29. Then, by changing the phases of the currents flowing through the electrodes 26 and 27 and the exciting coils 28 and 29, a rotating magnetic field can be applied to the object 10 to be inspected, and the scratched portion extending in any direction on the surface of the object 10 to be inspected. Leakage magnetic flux can also be generated from.

The configuration of the magnetized portion 12 is not particularly limited, and may be configured so that a magnetic field is applied to the object to be inspected 10 to magnetize at least the surface layer portion of the object to be inspected 10. The magnetized portion 12 has a configuration in which the object to be inspected 10 is magnetized by a magnetization method different from the above, such as an interpolar method in which the object to be inspected 10 is arranged between the magnetic poles of an electromagnet or a permanent magnet to magnetize the object to be inspected 10. The magnetization method may be appropriately selected according to the form of the object to be inspected 10.

The spraying unit 13 is configured to spray the test solution on the object 10 to be inspected in a state of being magnetized by the magnetizing unit 12. More specifically, the spraying unit 13 is connected to the stirring tank 20 of the test liquid tank 11, and the test liquid stored in the stirring tank 20 in a stirred state in which magnetic powder is dispersed is applied to the object 10 to be inspected. It is configured to be sprayed. The spraying unit 13 includes a spraying pump 30 for pumping the test solution, a spraying nozzle 31 for discharging the test solution pressure-fed by the spraying pump 30, a switching valve 32, and the like.

The suction side of the spray pump 30 is connected to the stirring tank 20 of the test liquid tank 11 by the pipe 33a. The pipe 33a is substantially the center of the bottom wall 25 of the tank body 22 and is connected to the bottom end portion 25b. The discharge side of the spray pump 30 is connected to the switching valve 32 by the pipe 33b. The spray nozzle 31 is arranged above the object to be inspected 10 and is connected to the switching valve 32 by the pipe 33c. In addition to the pipes 33b and 33c, the switching valve 32 is connected to the other end of the pipe 33d whose one end is connected to the stirring tank 20 of the test liquid tank 11.

The switching valve 32 is configured so that the test liquid pumped by the spraying pump 30 can flow through the pipe 33c to which the spraying nozzle 31 is connected or the pipe 33d connected to the stirring tank 20. The switching valve 32 is a 3-port air-operated valve that operates by air pressure, and is configured so as not to be affected by magnetic powder contained in the test solution. A circulation circuit 34 is formed in which the stirring tank 20, the spray pump 30, and the switching valve 32 to which the spray nozzle 31 is branched and connected are circulated and connected by the pipes 33a, 33b, 33d.

The test solution constantly circulates in the circulation circuit 34, and the test solution circulating in the circulation circuit 34 is maintained in a stirred state in which magnetic powder is dispersed. Then, when the test liquid is sprayed from the spray nozzle 31, the test liquid is sent from the switching valve 32 to the spray nozzle 31. Here, since the test liquid in the pipe 33c when the test liquid circulates in the circulation circuit 34 does not flow, the magnetic powder is in a state of settling without being dispersed. However, the pipe 33c only connects the spray nozzle 31 and the switching valve 32, and the amount of the inspection liquid in the pipe 33c is very small. Therefore, the spraying unit 13 can instantly spray the inspection liquid in which the magnetic powder is dispersed, the waiting time until the inspection liquid in which the magnetic powder is dispersed is small, and the flaw detection time can be shortened.

The spray nozzle 31 is configured to discharge the test liquid from a large number of discharge ports and spray the test liquid. The discharge state of the test liquid to be sprayed can be appropriately selected, and can be changed by changing the number, shape, opening area, flow rate of the test liquid, etc. of the spray nozzle 31. For example, the spray nozzle 31 may be configured to include a throttle mechanism capable of adjusting the opening area of the discharge port. The flow rate of the test solution can be adjusted by changing the discharge amount of the spray pump 30. The flow rate control valve or the like may be provided in the pipe 33b or the pipe 33c to adjust the flow rate of the test liquid sprayed from the spray nozzle 31.

Here, as shown in FIG. 3, the pipe 33d constituting the circulation circuit 34 is a stirring tank so that the inspection liquid of the stirring tank 20 is swirled by the inspection liquid discharged from the pipe 33d to the stirring tank 20. Connected to 20. Then, the test solution in the stirring tank 20 is swirled to flow, so that the test solution in the stirring tank 20 is maintained in a stirred state in which magnetic powder is dispersed. Therefore, the magnetic particle flaw detector 1 uses a device that stirs the test liquid in the stirring tank 20, for example, a stirrer provided with a stirrer arranged in the test liquid in the stirring tank 20 and a rotating device for rotating the stirrer. The test solution in the stirring tank 20 can be stirred with a simple structure without any problem, and the productivity is improved.

In FIG. 3, the pipe 33d is connected to the stirring tank 20 so that the test solution flows counterclockwise (counterclockwise) in a vortex, but the pipe 33d flows clockwise (clockwise) in a vortex. 33d may be connected to the stirring tank 20.

Further, from the viewpoint of preferably stirring the test liquid in the stirring tank 20, the discharge direction of the test liquid protruding from the pipe 33d to the stirring tank 20 is substantially horizontal, and the side wall 24 is viewed in a plan view (FIG. 3). It is preferable that the angle θ formed by the straight line L2 of the alternate long and short dash line indicating the tangent line of the inner peripheral surface is 45 ° or less. Here, the straight line L1 of the alternate long and short dash line in FIG. 3 indicates the discharge direction of the test liquid to the stirring tank 20. The pipe 33d may be connected to the stirring tank 20 so that the discharge direction of the test liquid protruding into the stirring tank 20 is along the partition wall 23. Even in such a configuration, the test liquid in the stirring tank 20 is preferably stirred. can do.

Further, the connection portion between the pipe 33d and the stirring tank 20 is preferably located above the lower end of the partition wall 23, and more preferably 100 mm or more above the lower end of the partition wall 23. With such a configuration, the test solution in the stirring tank 20 can be maintained in the stirred state without significantly disturbing the stationary state of the test solution in the settling tank 21.

The flow velocity of the test liquid discharged from the pipe 33d to the stirring tank 20 is appropriately set according to the size of the stirring tank 20, and is preferably 500 mm / s to 1000 mm / s, for example. With such a configuration, the test solution in the stirring tank 20 can be effectively stirred. If the flow velocity of the test solution is less than 500 mm / s, it becomes difficult to maintain the test solution in a stirred state. If the flow velocity of the test solution is larger than 1000 mm / s, it becomes difficult to maintain the test solution in the settling tank 21 in a stationary state. The flow velocity of the test liquid can be adjusted by changing the discharge amount of the spray pump 30 or changing the diameter of the pipe 33d at the connection portion with the stirring tank 20. In the circulation circuit 34, for example, a throttle valve or the like may be provided at the connection portion between the pipe 33d and the stirring tank 20 to adjust the flow velocity of the test liquid discharged from the pipe 33d to the stirring tank 20.

Here, the pipe 33a is substantially the center of the bottom wall 25 of the tank body 22 and is connected to the bottom end portion 25b. On the other hand, since the inside of the tank body 22 is partitioned into the stirring tank 20 and the settling tank 21 by the partition wall 23, the center of the spiral flow is the center of the bottom wall 25 of the tank body 22 in a plan view (FIG. 3). To the side (right side) of the stirring tank 20. Therefore, the connection portion between the pipe 33a connected to the spray pump 30 and the tank body 22 is arranged at a position deviated from the center of the spiral flow of the test liquid in a plan view. With such a configuration, it is possible to suppress the mixing of air into the test solution sprayed from the spray nozzle 31 and prevent a decrease in the detection accuracy of the scratched portion.

More specifically, at the center of the spiral flow of the test solution, it is easy to suck in air. When the connection portion between the pipe 33a and the tank body 22 is located near the center of the spiral flow of the test liquid, the sucked air is sent to the spray nozzle 31 together with the test liquid, and the inspection is mixed with a large amount of air. The liquid may be sprayed on the object 10 to be inspected. If a large amount of air is mixed in the test solution, the test solution is likely to be sprayed unevenly, the test solution is sprayed unevenly, and the detection accuracy of the scratched portion is lowered. Therefore, by arranging the connection portion between the pipe 33a and the tank body 22 at a position deviated from the center of the spiral flow of the test liquid in a plan view, it is possible to prevent a decrease in the detection accuracy of the scratched portion.

The spraying unit 13 sprays the test solution onto the object 10 to be inspected from above. The test solution to be sprayed is a test solution in a stirred state stored in the stirring tank 20. The sprayed test liquid flows on the surface of the object to be inspected 10 due to the force and gravity when it is discharged from the spray nozzle 31. Since at least the surface layer portion of the object to be inspected 10 is magnetized by the magnetized portion 12, when a scratched portion as a defect exists on the surface of the object to be inspected 10, a leakage magnetic field is generated due to the scratched portion. When the magnetic powder contained in the test solution passes over the scratched portion, it is attracted to the scratched portion by this leakage magnetic field. Then, the magnetic powder gathers on the scratched portion by this leakage magnetic field, so that the magnetic powder instruction pattern caused by the scratched portion is formed.

From the viewpoint of preferably forming the magnetic powder instruction pattern, the flow velocity of the test solution flowing on the surface of the object 10 to be inspected is preferably about 20 mm / s to 100 mm / s, and the spray nozzle 31 so as to have such a flow velocity. Adjust the discharge speed, discharge rate, etc. of the test liquid discharged from the vehicle as appropriate. If the flow velocity of the test liquid is larger than 100 mm / s, the magnetic powder is flown without being attracted by the leakage flux, and it becomes difficult to form the magnetic powder instruction pattern. Then, the detection omission of the scratched portion occurs, and the detection accuracy of the scratched portion tends to decrease. On the other hand, if the flow velocity of the test solution is less than 20 mm / s, it takes a lot of time until the magnetic powder instruction pattern is formed. In addition, magnetic powder tends to remain in a portion different from the scratched portion, erroneous detection of the scratched portion increases, and the detection accuracy of the scratched portion tends to decrease.

The surplus test liquid sprayed on the object 10 to be inspected by the spraying unit 13 falls downward due to gravity and is collected by the test liquid collecting unit 15.

The spraying portion 13 is not limited to the above configuration, and may be configured such that it is connected to the stirring tank 20 of the test liquid tank 11 and the test liquid in the stirred state is sprayed on the object 10 to be inspected. For example, the pipe 33a may be a stirring tank 20 and may be connected to the side wall 24 of the tank body 22. Further, the spraying portion 13 may be configured not to include the switching valve 32 and the pipe 33d, that is, to be configured not to include the circulation circuit 34, and the spraying pump 30 and the spraying nozzle 31 may be connected by the pipe 33b. You can also. However, from the viewpoint of the above-mentioned productivity, spraying of a suitable test solution, and the like, it is preferable to have a configuration including the circulation circuit 34.

Further, the arrangement of the spray nozzle 31 is not particularly limited. The spraying unit 13 may be configured to spray the test solution of the stirring tank 20 onto the test object 10 from below or from the side of the test object 10. In the case of such a configuration, it is preferable that the magnetic particle inspection device 1 is configured such that a support portion (not shown) that supports the object to be inspected 10 rotates the object to be inspected 10 at a desired speed. With such a configuration, the flow velocity of the test solution flowing on the surface of the test object 10 (the relative flow velocity of the test solution with respect to the surface of the test object 10) can be changed by changing the rotation speed of the test object 10. It can be adjusted and is easy to use.

The cleaning unit 14 is an object 10 in a state of being magnetized by the magnetized unit 12, and is configured to spray the test solution on the object 10 to be inspected after the test solution is sprayed by the spray unit 13. .. More specifically, the cleaning unit 14 is a stationary test liquid connected to the upper part of the settling tank 21 of the test liquid tank 11 and in which the magnetic powder stored in the settling tank 21 is settled, and is located in the upper part of the settling tank 21. The test solution is configured to be sprayed on the object to be inspected 10. The cleaning unit 14 has a cleaning pump 35 for pumping the test liquid, a cleaning nozzle 36 for discharging the test liquid pressure-fed by the cleaning pump 35, and the like.

The suction side of the cleaning pump 35 is connected to the upper part of the settling tank 21 of the test liquid tank 11 by the pipe 37a. The cleaning nozzle 36 is arranged above the object to be inspected 10 like the spray nozzle 31, and is connected to the discharge side of the spray pump 30 by the pipe 37b.

In the settling tank 21 to which the cleaning unit 14 is connected, the test solution is stored in a stationary state in which the magnetic powder settles. The test solution in the upper part of the settling tank 21, that is, the supernatant is in a state of containing almost no magnetic powder. The cleaning unit 14 is connected to the upper part of the settling tank 21 of the test liquid tank 11 to spray the supernatant in a state in which almost no magnetic powder is contained on the object 10 to be inspected.

The cleaning nozzle 36 has the same configuration as the spray nozzle 31, and is configured to discharge the test liquid from a large number of discharge ports and spray the test liquid. The discharge state of the test liquid to be sprayed can be appropriately selected, and can be changed by changing the number, shape, opening area, flow rate of the test liquid, etc. of the cleaning nozzle 36. For example, the cleaning nozzle 36 may be configured to include a throttle mechanism capable of adjusting the opening area of the discharge port. The flow rate of the test solution can be adjusted by changing the discharge amount of the cleaning pump 35. A flow rate control valve or the like may be provided on the pipe 37b to adjust the flow rate of the test liquid sprayed from the cleaning nozzle 31.

The cleaning unit 14 sprays the test solution onto the object 10 to be inspected from above. The test solution to be sprayed is a supernatant of the test solution in a stationary state stored in the settling tank 21, and is a test solution containing almost no magnetic powder. The sprayed test solution flows on the surface of the object to be inspected 10 due to the force and gravity when it is discharged from the cleaning nozzle 36. Here, the object 10 to be inspected is in a state of being magnetized by the magnetizing portion 12, and the inspection liquid sprayed by the cleaning portion 14 contains almost no magnetic powder. Therefore, the test liquid sprayed by the cleaning unit 14 can remove excess magnetic powder adhering to the surface of the object to be inspected 10, preventing false detection (overdetection) of the scratched portion and increasing the detection accuracy of the scratched portion. It will be improved. The excess magnetic powder is not the magnetic powder that is attracted to the scratched portion by the leakage magnetic field caused by the scratched portion as a defect to form an instruction pattern, but the magnetic powder that remains on the surface of the object 10 to be inspected.

From the viewpoint of effectively removing excess magnetic powder, the flow velocity of the test solution sprayed by the cleaning unit 14 and flowing on the surface of the object 10 to be inspected is preferably about 5 mm / s to 20 mm / s. The discharge speed, discharge amount, and the like of the test liquid discharged from the cleaning nozzle 36 are appropriately adjusted so as to have a flow velocity. When the flow velocity of the inspection liquid is larger than 20 mm / s, the magnetic powder attracted to the leakage flux is washed away by the inspection liquid, the magnetic particle instruction pattern is erased, and the detection omission of the scratched part is likely to occur, and the detection accuracy of the scratched part is likely to occur. Is likely to decrease. On the other hand, if the flow velocity of the test solution is less than 5 mm / s, the effect of removing the magnetic powder remaining on the surface of the object to be inspected 10 cannot be obtained.

The test liquid sprayed by the cleaning unit 14 falls downward due to gravity and is collected by the test liquid collecting unit 15. Therefore, the test liquid collecting unit 15 collects the test liquid sprayed by the above-mentioned spraying unit 13 together with the test liquid sprayed by the cleaning unit 14.

The cleaning unit 14 is not limited to the above configuration, but is connected to the upper part of the settling tank 21 of the test solution tank 11 and sprays the test solution stored in the settling tank 21 on the object 10 to be inspected. It suffices that it is configured to remove excess magnetic powder adhering to the surface of the object to be inspected 10. For example, the cleaning unit 14 may be configured to spray the test liquid stored in the settling tank 21 from the spray nozzle 31 of the spray unit 13. In such a configuration, the other end of the pipe 37b whose one end is connected to the discharge side of the cleaning pump 35 is connected to the pipe 33c which connects the spray nozzle 31 of the spraying portion 13 and the switching valve 32 via another switching valve. The configuration of connecting with each other can be illustrated. With such a configuration, the nozzle for spraying the test liquid can be shared by the spraying unit 13 and the cleaning unit 14, and space can be saved.

Further, the arrangement of the cleaning nozzles 36 is not particularly limited. The cleaning unit 14 may be configured to spray the supernatant of the test solution of the settling tank 21 onto the test object 10 from below or from the side of the test object 10. In the case of such a configuration, it is preferable that the magnetic particle inspection device 1 is configured such that a support portion (not shown) that supports the object to be inspected 10 rotates the object to be inspected 10 at a desired speed. With such a configuration, the flow velocity of the test solution flowing on the surface of the test object 10 (the relative flow velocity of the test solution with respect to the surface of the test object 10) can be changed by changing the rotation speed of the test object 10. It can be adjusted and is easy to use.

The test liquid collecting unit 15 is configured to collect the test liquid sprayed on the object 10 to be inspected by the spraying unit 13 and the cleaning unit 14 and return it to the test liquid tank 11. The test liquid recovery unit 15 has a recovery receiver 38 and a recovery pipe 39. The recovery receiver 38 is a saucer having a substantially U-shaped vertical cross section, and is arranged below the object to be inspected 10. The bottom of the collection receiver 38 is located above the liquid level of the test liquid in the test liquid tank 11. One end of the recovery pipe 39 is connected to the bottom of the recovery receiver 38, and the other end is connected to the test liquid tank 11.

Then, the test liquid collecting unit 15 collects the test liquid sprayed on the object 10 to be inspected by the spraying unit 13 and the cleaning unit 14 by the collection receiver 38, and returns the collected test liquid to the test liquid tank 11. Therefore, the test liquid collected by the test liquid recovery unit 15 is reused as the test liquid sprayed by the spraying unit 13 and the cleaning unit 14, and the burden on the environment can be reduced and the disposal cost of the test liquid can be reduced. ..

Here, the test liquid collected by the test liquid recovery unit 15 is a test liquid sprayed by the spraying unit 13 and the cleaning unit 14, both of which are stored in the test liquid tank 11. That is, although the amount of the inspection liquid used in the magnetic particle inspection device 1 that adheres to the surface of the object 10 to be inspected is reduced, water as a solvent is newly mixed when the cleaning unit 14 removes excess magnetic powder. There is no such thing. By reusing the collected test solution as it is, the total amount of magnetic powder contained in the test solution and the total amount of water as a solvent of the test solution hardly change. Therefore, the magnetic particle inspection device 1 can reuse the recovered test solution with a simple configuration without having a device or the like for adjusting the magnetic particle concentration of the recovered test solution, and can determine the magnetic particle concentration of the test solution in the stirring tank 20. Can be maintained within the range of. Then, the detection accuracy of the scratched portion does not decrease due to the decrease in the magnetic particle concentration of the test solution, and the detection accuracy of the scratched portion can be maintained at a certain level or higher.

From the viewpoint of maintaining the detection accuracy of the scratched portion at a certain level or higher, the other end of the recovery pipe 39 is preferably an inspection liquid tank 11 and is connected to the settling tank 21. The test solution collected by the test solution recovery unit 15 is the test solution sprayed by the spraying unit 13 and the cleaning unit 14. The test solution sprayed by the spraying unit 13 is a test solution in a stirred state stored in the stirring tank 20. On the other hand, the test solution sprayed by the cleaning unit 14 is a stationary test solution stored in the settling tank 21, and is a supernatant containing almost no magnetic powder. That is, the magnetic powder concentration of the test liquid collected by the test liquid collecting unit 15 is smaller than the magnetic powder concentration of the test liquid stored in the stirring tank 20, and the magnetic powder concentration in the supernatant of the test liquid stored in the settling tank 21. Is greater than.

When the test liquid collected by the test liquid recovery unit 15 is returned to the stirring tank 20, the magnetic particle concentration of the test liquid in the stirring tank 20 temporarily decreases and is contained in the test liquid sprayed by the spraying unit 13. The amount of magnetic powder produced may decrease, making it difficult to form a magnetic particle instruction pattern. On the other hand, when the test liquid collected by the test liquid recovery unit 15 is returned to the settling tank 21, the magnetic powder concentration of the test liquid in the stirring tank 20 hardly changes, and it does not become difficult to form the magnetic powder instruction pattern. Therefore, it is preferable to connect the other end of the recovery pipe 39 to the settling tank 21 so that the test liquid collected by the test liquid recovery unit 15 is returned to the settling tank 21.

Further, from the viewpoint of increasing the detection accuracy of the scratched portion, the other end of the recovery pipe 39 is preferably connected to the lower part of the settling tank 21, and as shown in FIG. 3, a stirring tank is connected to the lower part of the settling tank 21. It is preferable that the 20 is connected to face the surface. As described above, the magnetic particle concentration of the test solution collected by the test solution collecting unit 15 is smaller than the magnetic particle concentration of the test solution stored in the stirring tank 20, and the supernatant of the test solution stored in the settling tank 21. It is larger than the magnetic particle concentration in.

When the test liquid collected by the test liquid recovery unit 15 is returned to the upper part of the settling tank 21, the magnetic particle concentration of the test liquid on the upper part of the settling tank 21 which is the supernatant becomes high. Then, since the cleaning unit 14 sprays the inspection liquid (supernatant) having a high magnetic powder concentration on the inspection object 10, the magnetic powder of the sprayed inspection liquid remains on the inspection object 10 and is excessive. It becomes difficult to effectively remove the magnetic powder, and the detection accuracy of the scratched portion may decrease. Therefore, it is preferable to connect the other end of the recovery pipe 39 to the settling tank 21 so that the test liquid collected by the test liquid collecting unit 15 is returned to the lower part of the settling tank 21.

Further, the other end of the recovery pipe 39 is connected to the lower part of the settling tank 21 so as to face the stirring tank 20, so that the test liquid discharged from the recovery pipe 39 to the settling tank 21 is connected to the bottom of the settling tank 21. The settled magnetic powder can be moved to the stirring tank 20. Therefore, the inspection liquid having a high magnetic powder concentration is pushed out to the stirring tank 20, and the decrease in the magnetic powder concentration of the inspection liquid in the stirring tank 20 can be further prevented.

The slope of the reduced diameter portion 25a of the bottom wall 25 of the tank body 22 which is the bottom surface of the settling tank 21 so that the test liquid discharged from the recovery pipe 39 to the settling tank 21 flows along the bottom surface of the settling tank 21. It is more preferable to connect the recovery pipe 39 to the settling tank 21 in correspondence with the above. With such a configuration, the magnetic powder settled at the bottom of the settling tank 21 can be more effectively moved to the stirring tank 20, and the decrease in the magnetic powder concentration of the test solution in the stirring tank 20 can be further prevented.

Here, the test liquid recovery unit 15 further includes an exciting coil 40 as a recovery magnetic powder magnetizing unit that applies a magnetic field into the recovery pipe 39. The recovery pipe 39 penetrates the exciting coil 40. The exciting coil 40 can apply a magnetic field into the recovery pipe 39 by flowing an electric current. The magnetic powder of the test liquid passing through the magnetic field formed by the exciting coil 40 is magnetized and gathered together by the magnetic force. Then, the test solution containing the bonded magnetic powder is sent to the settling tank 21.

Since the settling speed of the magnetic powder is proportional to the square of the particle size, the settling speed of the magnetic powder can be increased by gathering and binding the magnetic powder by magnetic force. Therefore, when the inspection liquid recovery unit 15 is provided with the exciting coil 40, even when the particle size of the magnetic powder is relatively small, for example, 5 μm or less, the magnetic powder can be combined to increase the settling speed of the magnetic powder, and precipitation can be achieved. It is possible to surely form the supernatant containing almost no magnetic powder in the tank 21. Then, it is possible to prevent the amount of magnetic powder contained in the inspection liquid sprayed by the cleaning unit 14 from increasing and the effect of removing the excess magnetic powder from being reduced, and it is possible to increase the detection accuracy of the scratched portion. Further, even when the capacity of the settling tank 21 is small, the settling speed of the magnetic powder can be increased to surely form a supernatant containing almost no magnetic powder, and the detection accuracy of the scratched portion can be increased.

When the magnetic powder bonded by the exciting coil 40 is moved to the stirring tank 20, it is separated by the stress generated by the flow of the test liquid in the stirring tank 20. Therefore, the particle size of the magnetic powder to be sprayed does not change, and the detection accuracy of the scratched portion does not change.

The strength of the magnetic field applied to the recovery pipe 39 by the exciting coil 40 allows the magnetic powder to be bonded without the magnetic powder staying in the vicinity of the exciting coil 40 due to the magnetic force, and the combined magnetic powder is the test solution in the stirring tank 20. For example, it is preferably 50 oersted to 300 oersted, and more preferably about 200 oersted so as to be separated by the stress generated by the flow. The strength of the magnetic field can be adjusted by adjusting the radius, length, number of turns, current, etc. of the exciting coil 40. For example, when the diameter of the recovery pipe 39 is about 35 mm, the exciting coil 40 may have a radius of 50 mm to 100 mm, a length of 50 mm to 150 mm, a number of turns of 5 to 20, and a flowing current of 100 A to 500 A. preferable. The waveform of the current flowing through the exciting coil 40 is not particularly limited, and may be an AC wave of 50 Hz or 60 Hz, or a rectified wave.

Further, in the recovery pipe 39, it is preferable that the portion of the recovery pipe 39 in which the exciting coil 40 is arranged is formed of a non-magnetic and non-conductor material such as resin. With such a configuration, it is possible to prevent the magnetic powder magnetized by the exciting coil 40 from adhering to the recovery pipe 39. It is preferable that the recovery pipe 39 is made of a non-magnetic and non-conductor material in a range from both ends of the exciting coil 40 to a position separated from both ends by 50 mm or more outward.

Further, the position where the exciting coil 40 is arranged is not particularly limited. However, it is preferable that the exciting coil 40 is arranged at a position separated from the connection portion between the recovery pipe 39 and the inspection liquid tank 11 by 50 mm or more. With such a configuration, it is possible to prevent the influence of the magnetic field formed by the exciting coil 40 from affecting the test liquids of the test liquid tank 11 and the test liquid tank 11. For example, it is possible to prevent magnetic powder from adhering to or staying in the vicinity of the connection portion between the recovery pipe 39 and the inspection liquid tank 11.

Further, the recovered magnetic powder magnetized portion is not limited to the above-mentioned exciting coil 40, and may be any one capable of applying a magnetic field into the recovered pipe 39, and may be, for example, an electromagnet or the like.

Further, from the viewpoint of increasing the settling speed of the magnetic powder, a settling tank magnetic powder magnetized portion for applying a magnetic field may be provided in the settling tank 21. As the settling tank magnetic powder magnetized portion, for example, an exciting coil can be used in the same manner as the above-mentioned recovered magnetic powder magnetized portion. The exciting coil as the magnetized portion of the magnetic powder in the settling tank is subjected to an electric leakage treatment and is arranged in the lower part of the settling tank 21 in a direction in which the axial direction is parallel to the vertical direction. The exciting coil as the magnetic particle magnetizing portion of the settling tank can apply a magnetic field to the lower part of the settling tank 21 by flowing an electric current. By applying a magnetic field to the lower part of the settling tank 21 by the exciting coil as the magnetizing portion of the magnetic powder in the settling tank, the magnetic powder located in the upper part is attracted to the exciting coil, and the magnetic powder located in the vicinity of the exciting coil is bonded. Then, the settling speed of the magnetic powder can be increased, and the same effect as the above-mentioned recovered magnetic powder magnetized portion can be obtained.

It is preferable that the exciting coil as the magnetic particle magnetizing portion of the settling tank is configured to apply a magnetic field into the settling tank 21 at predetermined time intervals, instead of constantly applying a magnetic field into the settling tank 21. With such a configuration, it is possible to prevent magnetic powder from adhering to the exciting coil as the magnetized portion of the magnetic powder in the settling tank and from staying in the vicinity of the exciting coil.

Further, the magnetic powder magnetizing portion of the settling tank is not limited to the above-mentioned exciting coil, and may be any one capable of applying a magnetic field to the lower part of the settling tank 21.

The test liquid collecting unit 15 is not limited to the above-mentioned configuration, and is configured to collect the test liquid sprayed by the spraying unit 13 and the cleaning unit 14 and return it to the test liquid tank 11. good. For example, the structure may not include the exciting coil 40 as the recovered magnetic powder magnetizing portion. Further, the test liquid recovery unit 15 may be configured to include a pump for pumping the test liquid collected by the recovery receiver 38 to the test liquid tank 11. With such a configuration, the recovery receiver 38 can be arranged below the liquid level of the test liquid in the test liquid tank 11, and the degree of freedom in design is increased. Further, the test liquid collected by the collection receiver 38 can be reliably returned to the inspection liquid tank 11, and overflow of the inspection liquid in the collection receiver 38 can be prevented. Further, the discharge speed of the test liquid discharged from the recovery pipe 39 to the settling tank 21 can be adjusted, and the magnetic powder settled in the settling tank 21 can be moved to the stirring tank 20 more effectively. It is possible to further prevent a decrease in the magnetic particle concentration of the test solution in No. 20. Further, the collection receiver 38 may be configured to cover the side of the object to be inspected 10. With such a configuration, the test solution sprayed by the spraying unit 13 and the cleaning unit 14 can be recovered more reliably.

The ultraviolet irradiation unit 16 is configured to irradiate the surface (outer peripheral surface) of the object to be inspected 10 imaged by the image pickup unit 17, which will be described later, with ultraviolet rays. The ultraviolet irradiation unit 16 includes an ultraviolet LED (Light Emitting Diode) or an ultraviolet lamp as a light source and a fan (not shown) as a cooling device. The ultraviolet irradiation unit 16 is arranged above the object to be inspected 10. Then, the ultraviolet irradiation unit 16 is magnetized by the magnetizing unit 12, the inspection liquid is sprayed by the spraying unit 13, the inspection liquid is sprayed by the cleaning unit 14, excess magnetic powder is removed, and the image is captured by the imaging unit 17. The surface of the inspection object 10 is irradiated with ultraviolet rays from above. Then, when there is a magnetic powder instruction pattern in the region irradiated with ultraviolet rays by the ultraviolet irradiation unit 16, the phosphor of the magnetic powder forming the magnetic powder instruction pattern is excited and emits light.

The configuration of the ultraviolet irradiation unit 16 is not particularly limited. For example, the ultraviolet irradiation unit 16 may be configured to be magnetically shielded in order to avoid the influence of the magnetic field generated by the magnetizing unit 12. Further, the ultraviolet irradiation unit 16 may be configured to irradiate ultraviolet rays in a pulsed manner. With such a configuration, it is not necessary for the ultraviolet irradiation unit 16 to be configured to be able to constantly irradiate high-intensity ultraviolet rays, and it is possible to make an inexpensive configuration and to expect a long life of the ultraviolet light source. ..

The imaging unit 17 magnetizes the surface (outer peripheral surface) of the object 10 to be inspected, which is magnetized by the magnetizing unit 12, sprayed by the spraying unit 13, and sprayed by the cleaning unit 14 to remove excess magnetic powder. It is configured to image. The imaging unit 17 is arranged above the object to be inspected 10 and images the surface of the object to be inspected 10 from above.

An area camera or a line camera can be used as the image pickup unit 17, and the image pickup unit 17 is not particularly limited. For example, a CCD (Charge Coupled Device) camera can be used. The shutter speed of the imaging unit 17 and the resolution of the image to be captured are appropriately set according to the intensity of the ultraviolet rays emitted by the ultraviolet irradiation unit 16 and the like.

The imaging unit 17 is not limited to the above configuration. For example, the imaging unit 17 may be configured to be magnetically shielded in order to avoid the influence of the magnetic field generated by the magnetizing unit 12. Further, when the ultraviolet irradiation unit 16 irradiates a pulse of ultraviolet rays, the imaging unit 17 is configured to take an image in synchronization with the pulse irradiation of the ultraviolet irradiation unit 16.

The detection unit (not shown here) detects defects on the surface of the object 10 to be inspected by reading the image signal (original image) captured by the imaging unit 17 and performing predetermined processing on the original image. Yes, the configuration will be described later.

Next, the control system of the magnetic particle inspection device 1 according to the present embodiment will be described. FIG. 4 is a block diagram of the control system of the magnetic particle inspection device 1. The magnetic particle inspection device 1 includes a control unit 19, in which the magnetization unit 12, the spraying unit 13, the cleaning unit 14, the ultraviolet irradiation unit 16, the imaging unit 17, the detection unit 18, and the like are controlled by the control unit 19, and is automatically controlled. It is configured so that a scratched portion as a defect on the surface of the object to be inspected 10 can be detected.

The control unit 19 is configured to control the operation of the magnetic particle inspection device 1 by reading input signals such as various set values and detection values by various sensors and outputting the control signals. Examples of the control unit 19 include a microcomputer (Central Processing Unit) that performs arithmetic processing and control processing, a main storage device that stores data, a timer, an input circuit, an output circuit, a power supply circuit, and the like. To. The main storage device exemplified by the ROM (Read Only Memory) and the EEPROM (Electrically Erasable Programmable Read Only Memory) stores a control program for executing the operation according to the present embodiment and various data. It should be noted that these various programs, data, and the like may be stored in an external storage device and read by the control unit 19.

A magnetizing unit 12, a spraying unit 13, a cleaning unit 14, an ultraviolet irradiation unit 16, an imaging unit 17, a detection unit 18, and the like are electrically connected to the control unit 19. Various sensors and the like other than those shown in FIG. 4 are electrically connected to the control unit 19.

Similar to the control unit 19, the detection unit 18 has a processing device that performs arithmetic processing and control processing, a main storage device that stores data, and the like. For example, a CPU, a main storage device, a timer, an input circuit, and an output circuit. , A microcomputer having a power supply circuit and the like. The main storage device stores a program for detecting a scratched portion as a defect from the original image, various data, and the like. The configuration of the detection unit 18 is not particularly limited. For example, the program and data stored in the main storage device may be stored in an external storage device and read by the detection unit 18.

As described above, the detection unit 18 reads the original image captured by the imaging unit 17 and performs predetermined image processing on the read original image. Examples of the image processing include a LUT (Look Up Table) conversion process, an enlargement / contraction process, a shading process, and a binarization process. Then, the detection unit 18 determines the presence or absence of a scratched portion in the image processed by the image processing, and detects the scratched portion.

The detection unit 18 is not particularly limited as long as it can detect a scratched portion from the original image captured by the imaging unit 17. For example, the detection unit 18 may be configured to process a plurality of image processes in parallel by pipeline processing. With such a configuration, the time required for determining the presence or absence of a scratched portion can be shortened.

The detection unit 18 detects the scratched portion by real-time processing linked with the imaging by the imaging unit 17. However, the detection unit 18 may detect the scratched portion by batch processing in which a plurality of original images captured by the imaging unit 17 are accumulated and then processed without interlocking with the imaging by the imaging unit 17. With such a configuration, the calculation load of the detection unit 18 is reduced, and the productivity is improved.

Further, the detection unit 18 may be integrally configured with the control unit 19. With such a configuration, the configuration of the magnetic particle flaw detector 1 is simplified and the productivity is improved.

The magnetic particle flaw detector 1 is not limited to the above configuration. When a test solution containing a simple magnetic powder whose surface is not coated with a phosphor is used, the magnetic particle flaw detector 1 includes, for example, an illumination unit that irradiates white light in place of the above-mentioned ultraviolet irradiation unit 16. Can be.

Further, the magnetic particle inspection device 1 may have a configuration in which the magnetizing unit 12, the spraying unit 13, the cleaning unit 14, the ultraviolet irradiation unit 16, and the like are manually operated by an operator. With such a configuration, the configuration of the control unit 19 is simplified.

Further, as shown in FIG. 5, the magnetic particle flaw detection device 1 may further include a level sensor 41, a magnetic powder concentration measuring device 42, a concentrated magnetic powder liquid supply device 43, and a liquid supply device 44. Here, FIG. 5 is a schematic configuration diagram showing a spraying unit 13, a cleaning unit 14, and a test liquid collecting unit 15 according to another embodiment. The magnetic particle flaw detecting device 2 according to another embodiment further includes a level sensor 41, a magnetic powder concentration measuring device 42, a concentrated magnetic powder liquid supply device 43, and a liquid supply device 44 in the magnetic particle flaw detecting device 1 described above. Other than these, the configuration is the same as that of the magnetic particle flaw detector 1 described above, and the description of the same configuration will be omitted. Further, in FIG. 5, the flow direction of the test liquid is indicated by an arrow d3, and the description of the magnetizing unit 12, the ultraviolet irradiation unit 16, the imaging unit 17, etc. is omitted as in FIG.

The level sensor 41 is configured to measure the liquid level height of the test liquid in the test liquid tank 11. Although the level sensor 41 is arranged in the stirring tank 20 of the test liquid tank 11, it may be arranged in the settling tank 21. As the level sensor 41, for example, a float type sensor that utilizes the buoyancy of the float, a differential pressure type sensor that measures the liquid level height from the pressure difference in the tank, an ultrasonic type sensor that uses ultrasonic waves, and the like can be used.

The magnetic powder concentration measuring device 42 is configured to measure the magnetic powder concentration of the test solution in the stirring tank 20. The magnetic powder concentration measuring device 42 is connected to the stirring tank 20 and includes a pump (not shown) for taking in the test liquid of the stirring tank 20, a measuring unit (not shown) for measuring the magnetic powder concentration of the taken-in test liquid, and the like. The magnetic particle concentration measuring device 42 is configured to return the taken-in test liquid to the stirring tank 20. The measuring unit is configured to optically measure the magnetic powder concentration by applying the absorptiometry and the relationship between the energy of visible light emitted by the phosphor of the magnetic powder and the magnetic powder concentration.

The configuration of the magnetic particle concentration measuring device 42 is not particularly limited. The magnetic powder concentration measuring device 42 may be connected to a pipe 33a or the like constituting the circulation circuit 34, as long as it can measure the magnetic powder concentration of the test liquid sprayed from the spraying unit 13. Further, the measuring unit may be configured to measure the magnetic powder concentration from the amount of magnetic powder precipitated in the test solution in a stationary state.

The concentrated magnetic powder liquid supply device 43 is configured to supply the concentrated magnetic powder liquid having a predetermined magnetic powder concentration and having a higher magnetic powder concentration than the inspection liquid of the stirring tank 20 to the stirring tank 20. The concentrated magnetic powder liquid supply device 43 includes a tank 45 for storing the concentrated magnetic powder liquid, a pump 46 for pumping the concentrated magnetic powder liquid in the tank 45 to the stirring tank 20, and the like, and supplies the concentrated magnetic powder liquid to the stirring tank 20 from above. It is configured as follows. The tank 45 includes a stirring device (not shown) that stirs the concentrated magnetic powder liquid.

The configuration of the concentrated magnetic powder liquid supply device 43 is not particularly limited, and it is sufficient that the concentrated magnetic powder liquid can be supplied to the stirring tank 20. From the viewpoint of maintaining the detection accuracy of the scratched portion at a certain level or higher, the concentrated magnetic powder liquid supply device 43 is a connecting portion between the spraying portion 13 and the inspection liquid tank 11, and is a connecting portion between the pipe 33a and the bottom wall of the tank body 22. It is preferable that the concentrated magnetic powder liquid is supplied to a position away from the connection portion with the bottom end portion 25b of 25.

The liquid supply device 44 is configured to supply only the solvent of the test liquid to the settling tank 21. The liquid supply device 44 includes a supply pipe 48 having an on-off valve 47 which is a 2-port solenoid valve. One end of the supply pipe 48 is connected to the water source 49, and the other end is arranged above the settling tank 21. Then, the liquid supply device 44 is configured to supply water, which is a solvent for the test solution, to the settling tank 21 from above.

The configuration of the liquid supply device 44 is not particularly limited, and it is sufficient that only the solvent of the test solution can be supplied to the settling tank 21. When the solvent of the test solution is white kerosene, only the white kerosene is supplied to the settling tank. It is configured to supply 21. From the viewpoint of increasing the detection accuracy of the scratched portion, the liquid supply device 44 is a connecting portion between the cleaning portion 14 and the inspection liquid tank 11, and is in the vicinity of the connecting portion between the pipe 37a and the side wall 24 of the tank body 22. It is preferably configured to supply water as a solvent for the test solution.

The level sensor 41, the magnetic particle concentration measuring device 42, the concentrated magnetic powder liquid supply device 43, and the liquid supply device 44 are electrically connected to the control unit 19 and are controlled by the control unit 19. Then, in the magnetic particle inspection device 2, the control unit 19 reads the detected value of the level sensor 41 and the measured value of the magnetic powder concentration measuring device 42, and the amount of the test liquid and the magnetic powder concentration of the stirring tank 20 according to the read values. Is configured to control the concentrated magnetic powder liquid supply device 43 and the liquid supply device 44 so that the amount and the magnetic powder concentration are predetermined.

With such a configuration, the magnetic particle concentration and the amount of the inspection liquid in the stirring tank 20 can be kept constant, and the detection accuracy of the scratched portion can be more reliably maintained at a certain level or higher. Further, the magnetic particle inspection device 2 has a configuration in which the minimum necessary concentrated magnetic particle liquid and water are supplied so as to compensate for the decrease in the inspection liquid, so that the amount of the inspection liquid does not increase unnecessarily and space is saved. It is possible to reduce the burden on the environment and the disposal cost of the inspection liquid.

Further, as shown in FIG. 6, the magnetic particle flaw detector 1 includes a transport device 50, a magnetized portion 112 corresponding to the spray nozzle 31 of the spraying portion 13, a magnetized portion 212 corresponding to the cleaning nozzle 36 of the cleaning unit 14, and the like. For example, it may be configured to detect a scratched portion on the surface of the object to be inspected 110 while transporting the object to be inspected 110 such as a long prismatic steel material. Here, FIG. 6 is a schematic configuration diagram showing a magnetic particle flaw detector 3 according to another embodiment. The magnetic particle flaw detection device 3 is configured to include two magnetizing portions 112 and 212 in place of the magnetizing portion 12 and further include a transport device 50 in the magnetic particle flaw detection device 1 described above. Further, in the magnetic particle inspection device 1 described above, the magnetic particle inspection device 3 includes a spray nozzle 31 of the spray unit 13, a cleaning nozzle 36 of the cleaning unit 14, a collection receiver 38 of the inspection liquid collection unit 15, an ultraviolet irradiation unit 16, and an imaging unit. The arrangement of 17 is different. However, the magnetic particle flaw detector 3 has the same configuration as the magnetic particle flaw detector 1 except for the arrangement of the magnetizing portions 112 and 212, the transport device 50, and the above-mentioned parts, and the description of the same configuration is omitted. Further, in FIG. 6, the transport direction of the object to be inspected 110 is indicated by an arrow d4, and the description of the inspection liquid tank 11 and the like is omitted as in FIG.

The conveyor 50 is a roller conveyor composed of a plurality of rollers and the like, and is configured to convey the object to be inspected 110 at a desired speed. Then, in FIG. 6, the object to be inspected 110 is conveyed from the side where the spray nozzle 31 of the spray unit 13 is located to the side where the image pickup unit 17 is located. The transport device 50 includes a transport distance measuring device (not shown) that measures the transport distance of the object to be inspected 110. The configuration of the transport device 50 is not particularly limited, and may be, for example, a belt conveyor composed of an endless belt or the like. Further, the transport device 50 may be configured to intermittently transport the object to be inspected 110.

The spraying portion 13 is connected to the stirring tank 20. The spray nozzle 31 of the spray unit 13 is located on the upstream side of the object to be inspected 110 in the transport direction and above the object to be inspected 110. The cleaning unit 14 is connected to the upper part of the settling tank 21.

The cleaning nozzle 36 of the cleaning unit 14 is located on the downstream side of the spray nozzle 31 in the transport direction and above the object to be inspected 110. When the object to be inspected 110 is intermittently transported by the transport device 50, the cleaning unit 14 may be configured to spray the test liquid stored in the settling tank 21 from the spray nozzle 31 of the spray unit 13. good.

The collection receiver 38 of the test liquid recovery unit 15 is arranged below the test object 110 so as to collect the test liquid sprayed on the test object 110 by the spray unit 13 and the cleaning unit 14.

The magnetized portion 112 is arranged corresponding to the spray nozzle 31 of the spraying portion 13. The magnetizing portion 112 applies a magnetic field to the object to be inspected 110 in contact using the coil method and the interpolar method, and magnetizes at least the surface layer portion of the portion to which the inspection liquid is sprayed by the spraying portion 13 of the object to be inspected 110. It is configured as follows. The magnetizing portion 112 has two annular through coils, two U-shaped pole-to-pole coils, and the like, and is configured to generate a uniform rotating magnetic field by passing alternating currents having different phases through them. Will be done. The configuration of the magnetizing portion 112 is not particularly limited, and the arrangement and number of the through coil and the U-shaped pole-to-pole coil and the like can be appropriately set. Further, the magnetized portion 112 may be configured to include an air blow device for adjusting the flow velocity of the magnetic particle inspection liquid sprayed on the surface of the object to be inspected 10.

The magnetized portion 212 is arranged corresponding to the cleaning nozzle 36 of the cleaning unit 14. The magnetized portion 212 has the same configuration as the magnetized portion 112, a magnetic field is applied to the object to be inspected 110 by contact using a coil method and an interpolar method, and the inspection liquid is sprayed by the cleaning unit 14 of the object to be inspected 110. It is configured to magnetize at least the surface layer of the site to be magnetized. The configuration of the magnetized portion 212 is not particularly limited as in the magnetized portion 112. Further, the magnetized portion 212 may be integrally formed with the magnetized portion 112.

The ultraviolet irradiation unit 16 and the image pickup unit 17 are arranged on the downstream side of the cleaning nozzle 36 in the transport direction and above the object to be inspected 110. When the object to be inspected 110 is intermittently transported by the transport device 50, the ultraviolet irradiation unit 16 and the imaging unit 17 may be arranged above the magnetizing unit 212.

The magnetic particle flaw detector 3 having the above configuration transports the inspected object 110 by the conveying device 50 and detects a scratched portion as a defect on the surface of the inspected object 110. The object to be inspected 110 is conveyed and magnetized in the rotating magnetic field region formed by the magnetizing portion 112, and the inspection liquid in the stirring tank 20 is sprayed from the spray nozzle 31 of the spraying portion 13. At this time, if a defect is present on the surface of the object to be inspected 110, a magnetic particle instruction pattern due to the defect is formed. The surplus test liquid sprayed from the spray nozzle 31 of the spray unit 13 to the object to be inspected 110 is collected by the test liquid recovery receiver 38, returned to the test liquid tank 11, and reused.

The object 110 to be inspected to which the test solution is sprayed from the spray nozzle 31 of the spray unit 13 is conveyed inward to the rotating magnetic field region formed by the magnetizing unit 212, and is also conveyed from the cleaning nozzle 36 of the cleaning unit 14 to the settling tank 21. The supernatant, which is a test solution and contains almost no magnetic powder, is sprayed. At this time, the magnetized state of the object to be inspected 110 is maintained by the magnetized portion 212, and excess magnetic powder is removed by the inspection liquid sprayed from the cleaning nozzle 36 of the cleaning portion 14. The test liquid sprayed from the cleaning nozzle 36 of the cleaning unit 14 to the object to be inspected 110 is collected by the test liquid collection receiver 38, returned to the test liquid tank 11, and reused.

The object 110 to be inspected from which excess magnetic powder has been removed is conveyed below the imaging unit 17 and imaged by the imaging unit 17. At this time, the region imaged by the imaging unit 17 is irradiated with ultraviolet rays from the ultraviolet irradiation unit 16. When there is a magnetic powder instruction pattern in this region, the phosphor of the magnetic powder forming the magnetic powder instruction pattern is excited and emits light. Then, the detection unit 18 performs a predetermined process on the original image captured by the imaging unit 17 to detect defects in the original image.

With such a configuration, even if the object to be inspected is long 110, the test solution is reused, the detection accuracy of the scratched portion is high, and the detection accuracy of the scratched portion is maintained at a certain level or higher. It is possible to search for scratches.

Further, the magnetic particle inspection devices 1, 2, and 3 are not limited by the size, and can be appropriately designed depending on the size of the object to be inspected 10, the amount of the inspection liquid to be sprayed, and the like. The horizontal cross-sectional area of the settling tank 21 is set so that a sufficient amount of supernatant can be generated by the cleaning unit 14. More specifically, it is preferable that the horizontal cross-sectional area of the settling tank 21 is larger than the value obtained by dividing the volume of the test solution sprayed by the cleaning unit 14 per unit time by the settling rate of the magnetic powder. With such a configuration, a larger amount of the supernatant liquid than the test liquid sprayed by the cleaning unit 14 is formed, and the detection accuracy of the scratched portion can be reliably maintained to be high.

Further, the magnetic particle flaw detectors 1, 2 and 3 according to the present embodiment described above can be freely combined within a range where no contradiction occurs. For example, the magnetic particle flaw detector 3 may be configured to include a level sensor 41 of the magnetic particle flaw detector 2, a magnetic powder concentration measuring device 42, a concentrated magnetic powder liquid supply device 43, and a liquid supply device 44.

As described above, the magnetic particle flaw detectors 1, 2, and 3 according to the present embodiment include an inspection liquid tank 11 for storing an inspection liquid containing magnetic powder and a magnetized portion for magnetizing the inspection objects 10, 110. 12, 112, 212, a spraying section 13 that sprays the test solution on the objects 10 and 110 to be inspected, a cleaning section 14 that sprays the test solution on the objects 10 and 110 to be inspected, and a spraying section 13 and a cleaning section 14 to spray the test solution. A test liquid recovery unit 15 for collecting the tested liquid and returning it to the test liquid tank 11 is provided, and the test liquid tank 11 is located between the bottomed tubular tank body 22 and the bottom wall 25 of the tank body 22. The inside of the tank body 22 has a gap, and has a partition wall 23 for partitioning the inside of the tank body 22 into a stirring tank 20 for storing the test liquid in a stirred state and a settling tank 21 for storing the test liquid in a stationary state, and the spraying portion 13 is a stirring tank. It is connected to 20 and the cleaning unit 14 is connected to the upper part of the settling tank 21.

According to the present embodiment, there is provided a magnetic particle flaw detector that can reuse the test solution with a simple configuration, has a high scratch detection accuracy, and maintains the scratch detection accuracy at a certain level or higher. Can be done.

Next, the outline of the magnetic particle flaw detection method according to the present embodiment will be described. In the following, the flaw detection of the scratched portion on the surface of the object to be inspected 10 by the magnetic particle flaw detector 1 shown in FIGS. 1 to 3 will be described as an example. FIG. 7 is a flow chart showing an outline of the magnetic particle flaw detection method according to the present embodiment. In this embodiment, at least a step of magnetizing the object to be inspected 10, a step of spraying the test solution of the stirring tank 20 on the object to be inspected 10, and a step of spraying the test solution on the upper part of the settling tank 21 on the object to be inspected 10. It is characterized by including a step of collecting the test liquid sprayed on the object to be inspected 10 and returning it to the test liquid tank 11. In the following, each step will be described in more detail.

First, the object to be inspected 10 is magnetized by the magnetizing unit 12 (step S1). As described above, the magnetizing portion 12 magnetizes the surface layer portion of the object 10 to be inspected by using the energization method and the coil method. The magnetized portion 12 includes electrodes 26 and 27 that come into contact with both ends of the object 10 to be inspected and allow an electric current to flow through the object 10 to be inspected, and exciting coils 28 and 29 arranged in the vicinity of both ends of the object 10 to be inspected. Then, currents having different phases are passed through the electrodes 26 and 27 and the exciting coils 28 and 29 to apply a rotating magnetic field to the object 10 to be inspected to magnetize the object 10 to be inspected. Therefore, when there is a scratch on the surface of the object 10 to be inspected, leakage flux is generated from the scratch regardless of the extending direction of the scratch. The magnetization of the object to be inspected 10 is continued until the imaging by the imaging unit 17 described later is completed.

Next, the test solution of the stirring tank 20 is sprayed on the surface of the object 10 to be inspected by the spraying unit 13 (step S2). As described above, the spraying unit 13 is connected to the stirring tank 20 of the test liquid tank 11, and sprays the tested liquid in a stirred state in which magnetic powder is dispersed on the surface of the object 10 to be inspected. At this time, the object 10 to be inspected is magnetized, and if there is a scratch on the surface of the object 10 to be inspected, the magnetic powder contained in the inspection liquid is attracted to the leakage magnetic field caused by the scratch, and the scratched portion A magnetic particle instruction pattern is formed due to the above. The surplus test solution sprayed on the object to be inspected 10 by the spraying unit 13 falls downward due to gravity.

Next, the excess test liquid sprayed by the spraying unit 13 is collected by the test liquid collecting unit 15 and returned to the test liquid tank 11 (step S3). As described above, the test liquid recovery unit 15 has a recovery receiver 38 arranged below the object to be inspected 10, and a recovery pipe 39 connecting the bottom of the recovery receiver 38 and the test liquid tank 11. Then, the surplus test liquid sprayed by the spraying unit 13 and dropped by gravity is collected by the test liquid collecting unit 15 and returned to the test liquid tank 11 for reuse. Therefore, it is possible to reduce the burden on the environment and the cost of disposing of the test solution.

Next, the cleaning unit 14 sprays the test solution on the upper part of the settling tank 21 onto the surface of the object 10 to be inspected (step S4). As described above, the cleaning unit 14 is connected to the upper part of the settling tank 21 of the test solution tank 11, and is a stationary test solution in which the magnetic powder is settled, and the supernatant is in a state where the magnetic powder is hardly contained. It is sprayed on the surface of the object to be inspected 10. At this time, the object to be inspected 10 is magnetized, and the inspection solution sprayed by the cleaning unit 14 contains almost no magnetic powder. Therefore, the excess test solution adhered to the surface of the object to be inspected 10 by the inspection solution sprayed by the cleaning unit 14 Magnetic particles are removed. The bottom of the settling tank 21 communicates with the bottom of the stirring tank 20.

Here, the excess magnetic powder is not the magnetic powder that is attracted to the scratched portion by the leakage magnetic field caused by the scratched portion as a defect to form an instruction pattern, but the magnetic powder that remains on the surface of the object 10 to be inspected. The test solution sprayed on the object to be inspected 10 by the cleaning unit 14 falls downward due to gravity.

Next, the test liquid collected by the test liquid collecting unit 15 and returned to the test liquid tank 11 are performed (step S5). Similar to step S3, the inspection liquid sprayed by the cleaning unit 14 and dropped by gravity is collected by the collection unit 15 and returned to the inspection liquid tank 11 for reuse. Therefore, it is possible to reduce the burden on the environment and the cost of disposing of the test solution.

Here, the test liquids collected and returned to the test liquid tank 11 in steps S3 and S5 are the test liquids sprayed by the spraying unit 13 and the cleaning unit 14, both of which are stored in the test liquid tank 11. It is the test solution that has been used, and is returned to the test solution tank 11 in a mixed state. That is, although the amount of the test solution used in the magnetic particle flaw detector 1 that adheres to the surface of the object 10 to be inspected is reduced, water or the like as a solvent for the test solution is not newly mixed during the flaw detection. Then, by returning the test solution collected in steps S3 and S5 to the test solution tank 11 as it is and reusing it, the total amount of magnetic powder contained in the test solution and the total amount of water as the solvent of the test solution hardly change. Therefore, the recovered test solution can be reused with a simple structure without adjusting the magnetic particle concentration of the recovered test solution, and the magnetic powder concentration of the test solution in the stirring tank 20 is maintained within a predetermined range. be able to. Then, the detection accuracy of the scratched portion does not decrease due to the decrease in the magnetic particle concentration of the test solution, and the detection accuracy of the scratched portion can be maintained at a certain level or higher.

Next, the surface of the object to be inspected 10 is irradiated with ultraviolet rays by the ultraviolet irradiation unit 16 (step S6). The ultraviolet irradiation unit 16 is arranged above the object to be inspected 10. Then, it is magnetized by the magnetizing unit 12, the inspection liquid is sprayed by the spraying unit 13, and the inspection liquid is sprayed by the cleaning unit 14, and is a portion to be imaged by the imaging unit 17 from above on the surface of the object to be inspected 10. Irradiate with ultraviolet rays. When there is a magnetic powder instruction pattern in the region irradiated with ultraviolet rays by the ultraviolet irradiation unit 16, the phosphor of the magnetic powder forming the magnetic powder instruction pattern is excited and emits light.

Next, the surface of the object to be inspected 10 is imaged by the imaging unit 17 (step S7). An image is taken of the surface of the object 10 to be inspected, which is a region irradiated with ultraviolet rays by the ultraviolet irradiation unit 16 and from which excess magnetic powder has been removed in step S4. The captured original image is sent to the detection unit 18. The irradiation of ultraviolet rays (step S6) is continued until the imaging by the imaging unit 17 is completed.

Next, the detection unit 18 detects the scratched portion as a defect (step S8). The detection unit 18 reads the original image captured in the imaging of the object 10 to be inspected (step S7). The detection unit 18 performs predetermined image processing on the read original image, determines the presence or absence of a scratched portion in the image processed by the image processing, and detects the scratched portion. Then, the flaw detection is completed.

Here, the detection of the scratched portion is performed based on the original image in which the surface of the object to be inspected 10 from which the excess magnetic powder has been removed in step S7 is captured. Therefore, erroneous detection (overdetection) of the scratched portion is prevented, and the detection accuracy of the scratched portion is improved.

The magnetic particle flaw detection method is not limited to the above method. For example, the order of the magnetization of the object to be inspected 10 (step S1) and the spraying of the inspection liquid in the stirring tank 20 (step S2) may be changed. In the case of such a configuration, it is preferable that the spraying of the test solution in the stirring tank 20 (step S2) continues until a predetermined time elapses after the magnetization of the object 10 to be inspected 10 (step S1) is started. ..

Further, the magnetic particle flaw detection method may be a method in which the magnetic powder concentration adjusting step (step S9) shown in FIG. 8 is further included in the magnetic particle flaw detection method shown in FIG. Here, FIG. 8 is a flow chart showing an outline of the magnetic particle concentration adjusting step (step S9). The magnetic powder concentration adjusting step (step S9) includes a step of measuring the liquid level height and the magnetic powder concentration of the test liquid in the stirring tank 20 (step S10) and a step of supplying the concentrated magnetic powder liquid and water (step S11). .. The magnetic particle flaw detection method according to another embodiment further including the magnetic powder concentration adjusting step (step S9) corresponds to the flaw detection of the scratched portion on the surface of the object 10 to be inspected by the magnetic particle flaw detector 2 shown in FIG. ..

In the magnetic powder concentration adjusting step (step S9), after the liquid level height and magnetic powder concentration of the test liquid in the stirring tank 20 are measured (step S10), the concentrated magnetic powder liquid and water are supplied (step S11). ..

In step S10, the liquid level height of the test solution in the stirring tank 20 is measured by the level sensor 41. Further, the magnetic powder concentration of the test solution in the stirring tank 20 is measured by the magnetic powder concentration measuring device 42. The measured values of the level sensor 41 and the magnetic particle concentration measuring device 42 are sent to the control unit 19.

In step S11, the concentrated magnetic powder liquid is supplied to the stirring tank 20 from above by the concentrated magnetic powder liquid supply device 43. The concentrated magnetic powder liquid is a magnetic powder liquid having a predetermined magnetic powder concentration and a higher magnetic powder concentration than the inspection liquid in the stirring tank 20. Further, water, which is a solvent for the test liquid, is supplied to the settling tank 21 from above by the liquid supply device 44.

Here, in the supply of the concentrated magnetic powder liquid and water, the control unit 19 supplies the concentrated magnetic powder liquid supply device 43 and the liquid according to the measured value of the level sensor 41 and the measured value of the magnetic powder concentration measuring device 42 measured in step S10. This is done by controlling the device 44. Then, the concentrated magnetic powder liquid is supplied to the stirring tank 20 and water, which is the solvent of the test liquid, is precipitated so that the liquid amount and the magnetic powder concentration of the test liquid in the stirring tank 20 become the predetermined liquid amount and the magnetic powder concentration. It is supplied to the tank 21. In addition, only the concentrated magnetic powder liquid may be supplied to the stirring tank 20, and only water which is the solvent of the test liquid may be supplied to the settling tank 21. Further, when the measured value of the level sensor 41 and the measured value of the magnetic particle concentration measuring device 42 are within a predetermined range, step S9 is completed without performing step 11.

By adopting such a method, the magnetic particle concentration and the amount of the inspection liquid in the stirring tank 20 can be kept constant, and the detection accuracy of the scratched portion can be more reliably maintained at a certain level or higher. Further, the concentrated magnetic powder liquid and water in step S11 are supplied so as to compensate for the decrease in the test liquid, the amount of the test liquid does not increase, the burden on the environment is reduced, and the test liquid is discarded. Cost can be reduced.

The magnetic particle concentration adjusting step (step S9) may be performed between any steps in the magnetic particle flaw detection method shown in FIG. 7, and may be performed in parallel with any step, and the timing of performing step S9. Is not particularly limited. It is preferable that step S9 is performed at least before spraying the test solution of the stirring tank 20 by the spraying unit 13 (step S2), and may be performed before magnetic particle inspection is started. With such a configuration, the magnetic particle concentration of the inspection liquid sprayed on the object to be inspected 10 can be more reliably kept constant. On the other hand, when step S9 is performed after spraying the test solution of the stirring tank 20 by the spraying unit 13 (step S2), the magnetic powder concentration of the test solution to be sprayed on the object 10 to be inspected in the next magnetic particle inspection is determined. It can be a concentration.

As described above, the magnetic particle flaw detection method according to the present embodiment is an inspection in the magnetic particle flaw detection method in which the inspection object 10 is flawed using the inspection liquid containing the magnetic powder stored in the inspection liquid tank 11. The liquid tank 11 has a gap between the bottomed tubular tank body 22 and the bottom wall 25 of the tank body 22, and is stationary with the stirring tank 20 for storing the test liquid in a stirred state inside the tank body 22. A step of magnetizing the object to be inspected 10 having a partition wall 23 partitioning the settling tank 21 for storing the test solution in a state, a step of spraying the test solution of the stirring tank 20 onto the object to be inspected 10, and a settling tank 21. A step of spraying the test solution on the upper part of the test object 10 and a step of collecting the test solution sprayed on the test object 10 and returning it to the test liquid tank 11 are provided.

According to the present embodiment, it is possible to provide a magnetic particle flaw detection method in which the test solution can be reused with a simple configuration, the detection accuracy of the scratched portion is high, and the detection accuracy of the scratched portion is maintained at a certain level or higher. Can be done.

The present disclosure will be described in more detail and concretely with reference to Examples below. However, the present disclosure is not limited to the following examples.

<Material and measurement method>
[Example 1]
The magnetic particle flaw detector 1 according to the present embodiment shown in FIGS. 1 to 3 was used. That is, the magnetic particle inspection device 1 includes an inspection liquid tank 11 for storing an inspection liquid containing magnetic powder, a magnetizing portion 12 for magnetizing the inspection object 10, and a spraying portion 13 for spraying the inspection liquid on the inspection object 10. An inspection liquid tank including a cleaning unit 14 for spraying the inspection liquid on the object 10 to be inspected, and an inspection liquid collection unit 15 for collecting the inspection liquid sprayed by the spraying unit 13 and the cleaning unit 14 and returning the inspection liquid to the inspection liquid tank 11. Reference numeral 11 denotes a stirring tank 20 having a gap between the bottomed tubular tank main body 22 and the bottom wall 25 of the tank main body 22 and storing the agitated test liquid inside the tank main body 22 and a stationary state. It has a partition wall 23 that partitions the settling tank 21 for storing the test liquid, the spraying section 13 is connected to the stirring tank 20, and the cleaning section 14 is connected to the upper part of the settling tank 21.

A test solution is prepared by adding magnetic powder (manufactured by MARKTEC Corporation: Super Magna Fluorescent Magnetic Particle, LY-20) and a rust preventive agent (manufactured by MARKTEC Corporation: Super Keep rust preventive, AR-100K) to water. It was. The test solution was prepared so that the magnetic powder concentration was 1.0 g / L and the rust inhibitor concentration was 1%. As the object 10 to be inspected, 50 shafts formed from SCM415, having a length of 150 mm and a diameter of 30 mm were prepared. On the surface of each of the objects to be inspected 10, a scratch portion having a depth of 0.1 mm and a width of 10 μm extending axially was formed.

Then, the flaw detection of 50 objects to be inspected 10 was continuously performed by the magnetic particle flaw detection method shown in FIG. At this time, the tank body 22 was provided with a cylindrical side wall 24 and a bottom wall 25 having a reduced diameter portion 25a and a bottom end portion 25b, as shown in FIGS. 2 and 3. The total height of the tank body 22 is 400 mm, the height of the side wall 24 is 300 mm, the height of the bottom wall 25 is 100 mm, the horizontal cross-sectional area of the tank body 22 is 0.4 m ² , and the stirring tank 20 horizontal cross-sectional area was 0.35 m ^2, the horizontal cross-sectional area of the sedimentation tank 21 is 0.05 m ^2, the inclination angle of the reduced diameter portion 25a is 15.5 °, the pipes 33a, 33b, 33c, 33d Has a nominal diameter of 25 A (outer diameter is 34 mm, inner diameter is 27.6 mm). Each horizontal cross-sectional area is the horizontal cross-sectional area at the joint between the side wall 24 and the bottom wall 25. The gap between the lower end of the partition wall 23 and the bottom wall 25 was a substantially half-moon shape with a string length of 575 mm and an arrow height of 40 mm, and its area was 13700 mm ² . The test solution stored in the tank body 22 was 115 L, the test solution stored in the stirring tank 20 was about 100 L, and the test solution stored in the settling tank 21 was about 15 L. The strength of the magnetic field applied to the object 10 to be inspected by the magnetizing portion 12 was about 50 Oersted, and the average flow rate of the inspection liquid circulating in the circulation circuit 34 was 50 L / min. Further, in one flaw detection, the amount of the test solution sprayed from the spraying section 13 was 2 L, and the amount of the test solution sprayed from the cleaning section 14 was 1 L.

Further, as shown in FIG. 9, the time for spraying the test solution from the spraying section 13 was 3 seconds, and the time for spraying the test solution from the cleaning section 14 was 3 seconds. Here, FIG. 9 is a time chart showing the operation of the magnetizing portion 12, the spraying portion 13, and the cleaning portion 14, and shows a time chart for flaw detection of one inspected object 10. Specifically, the spraying section 13 starts spraying the test solution 1 second after the magnetic field starts to be applied to the object 10 to be inspected by the magnetizing section 12, and the cleaning section 14 finishes spraying the test solution by the spraying section 13. The spraying of the test solution was started 1 second after, and the magnetizing section 12 stopped applying the magnetic field to the object 10 to be inspected 5 seconds after the spraying of the test solution by the cleaning section 14 was completed. The imaging unit 17 imaged the object 10 to be inspected 1 second after the spraying of the inspection liquid of the cleaning unit 14 was completed. The flaws of 50 objects to be inspected 10 were continuously detected, and the time required to detect the flaws of one object to be inspected 10 was about 30 seconds.

Therefore, in the method according to the first embodiment, the test liquid tank 11 has a gap between the bottomed tubular tank body 22 and the bottom wall 25 of the tank body 22, and the inside of the tank body 22 is stirred. A step of magnetizing the object to be inspected 10 and a step of magnetizing the test object 10 and the test solution of the stirring tank 20 to be inspected, having a partition wall 23 partitioning the stirring tank 20 for storing the test solution and the settling tank 21 for storing the test solution in a stationary state. A step of spraying on the object 10, a step of spraying the test solution on the upper part of the settling tank 21 on the object 10 to be inspected, a step of collecting the test solution sprayed on the object 10 to be inspected and returning the test solution to the test solution tank 11. It had the characteristics related to this embodiment such as being provided with.

The test liquids sprayed from the spraying unit 13 and the cleaning unit 14 are not all discarded by the time the flaw detection of the 50 objects to be inspected is completed, but are collected by the inspection liquid collecting unit 15 and collected by the inspection liquid tank 11 Was returned to.

[Comparative Example 1]
Comparative Example 1 was the same as that of Example 1 except that steps S4 and S5 were omitted in the magnetic particle inspection method shown in FIG. 7. Comparative Example 1 did not have a step of spraying the inspection liquid on the upper part of the settling tank 21 onto the object 10 to be inspected in the magnetic particle inspection method. Therefore, the method according to Comparative Example 1 did not have the characteristics according to the present embodiment. The test liquid sprayed from the spraying unit 13 was collected by the test liquid collecting unit 15 and returned to the test liquid tank 11, and no test liquid was generated to be discarded.

<Evaluation method>
(Magnetic particle concentration of the test solution sprayed from the spraying unit 13)
For Example 1, the test solution sprayed from the spraying section 13 was collected every 10 flaw detections, and the magnetic particle concentration of the test solution was measured. The magnetic particle concentration of the test solution was 0.9 g / L to 1.0 g / L.

(Magnetic particle concentration of test solution sprayed from cleaning unit 14)
For Example 1, the test solution sprayed from the cleaning unit 14 was collected every 10 flaw detections, and the magnetic particle concentration of the test solution was measured. The magnetic particle concentration of the test solution was 0.2 g / L to 0.3 g / L.

(S / N of magnetic particle instruction pattern)
With respect to Example 1 and Comparative Example 1, from the images captured in the first flaw detection and the last flaw detection, the S / N of the magnetic powder instruction pattern (scratch portion) (ratio of the brightness S in the scratch portion and the brightness N other than the scratch portion). ) Was calculated. In Example 1, the S / N in the first flaw detection was 9.0 and the S / N in the last flaw detection was 9.3. In Comparative Example 1, the S / N in the first flaw detection was 6.4, and the S / N in the last flaw detection was 6.6.

The following points were derived from the above-mentioned examples. In Example 1, the concentration of the test solution sprayed from the spraying portion 13 is 0.9 g / L to 1.0 g / L even when the flaw is continuously detected, and the test solution is sprayed from the spraying portion 13. It was shown that the concentration of the test solution was kept substantially constant. Further, in Example 1, even when the flaw detection is continuously performed, the concentration of the test solution sprayed from the cleaning unit 14 is 0.2 g / L to 0.3 g / L, and the cleaning unit 14 It was shown that the test solution sprayed from the water was maintained in a state of containing almost no magnetic powder. Further, in Example 1, excess magnetic powder was removed by the test solution sprayed from the cleaning unit 14 in step S4. Then, in Example 1, the S / N of the magnetic particle instruction pattern was higher than that of Comparative Example 1, and a clearer magnetic particle instruction pattern was formed than in Comparative Example 1. Further, in Example 1, even when the flaw was continuously detected, excess magnetic powder was removed, the S / N was kept substantially constant, and a clear magnetic powder instruction pattern was formed.

From the results of the above examples, in the magnetic particle flaw detection device 1 and the magnetic particle flaw detection method according to the present embodiment, the test solution is reused with a simple configuration, and even when the flaw detection is continuously performed, the inspection liquid is reused. It was shown that a clear magnetic particle instruction pattern can be formed, the detection accuracy of the scratched portion is high, and the detection accuracy of the scratched portion can be maintained above a certain level. Therefore, in the present embodiment, it is possible to provide a magnetic particle flaw detector that can reuse the test solution with a simple configuration, has a high scratch detection accuracy, and maintains the scratch detection accuracy at a certain level or higher. It has been shown.

The present disclosure can be suitably used for a magnetic particle flaw detector that detects flaws using magnetic powder, and a magnetic particle flaw detector method. However, the present disclosure is not limited to the embodiments and examples described above. The magnetic particle flaw detector and the magnetic particle flaw detector of the present disclosure are useful for flaw detection on the surface of any magnetic material such as shafts, pipes, and steel materials, and particularly when continuous flaw detection and when a large amount of inspection liquid is used. It is useful for.

1, 2, 3 Magnetic particle inspection device 10, 110 Inspection liquid tank 12 Magnetized part 13 Spraying part 14 Cleaning part 15 Inspection liquid collecting part 20 Stirring tank 21 Sedimentation tank 22 Tank body 23 Partition wall 24 Side wall 25 Bottom wall 30 Spraying Pump 31 Scatter nozzle 32 Switching valve 33a, 33b, 33c, 33d Piping 34 Circulation circuit 38 Recovery receiver 39 Recovery piping 40 Excitation coil (recovery magnetic particle magnetized part)
41 Level sensor 42 Magnetic particle concentration measuring device 43 Concentrated magnetic particle liquid supply device 44 Liquid supply device

Claims (9)

A test liquid tank that stores the test liquid containing magnetic powder,
The magnetized part that magnetizes the object to be inspected and
A spraying portion for spraying the test solution on the object to be inspected,
A cleaning unit that sprays the test solution onto the object to be inspected,
It is provided with a test solution collecting section for collecting the test solution sprayed by the spraying section and the cleaning section and returning the test solution to the test solution tank.
The test liquid tank is
With a bottomed tubular tank body
A partition wall having a gap between the bottom wall of the tank body and partitioning the inside of the tank body into a stirring tank for storing the test solution in a stirred state and a settling tank for storing the test solution in a stationary state. Have and
A magnetic particle flaw detector, characterized in that the spraying portion is connected to the stirring tank and the cleaning portion is connected to the upper part of the settling tank. The bottom surface of the settling tank is characterized in that it inclines downward toward the stirring tank.
The magnetic particle flaw detector according to claim 1. The spraying portion has a circulation circuit in which the stirring tank, the spraying pump, and the switching valve to which the spraying nozzle is branched and connected are circulated and connected by piping.
The pipe is connected to the stirring tank so that the test liquid in the stirring tank flows in a spiral shape by the test liquid discharged to the stirring tank.
The magnetic particle flaw detector according to claim 1 or 2. The test liquid recovery unit
The collection receiver placed below the object to be inspected,
One end has a collection pipe connected to the collection receiver, and the other end has a collection pipe connected to the test liquid tank.
The other end of the recovery pipe is connected to the lower part of the settling tank so as to face the stirring tank.
The magnetic particle flaw detector according to any one of claims 1 to 3. Further, the recovery pipe is provided with a recovery magnetic powder magnetized portion for applying a magnetic field.
The magnetic particle flaw detector according to claim 4. Further, the settling tank is provided with a magnetic powder magnetizing portion of the settling tank to which a magnetic field is applied.
The magnetic particle flaw detector according to any one of claims 1 to 5. Further, a level sensor for measuring the liquid level of the test liquid in the test liquid tank and a level sensor
A magnetic particle concentration measuring device for measuring the magnetic particle concentration of the test solution in the stirring tank, and
A concentrated magnetic powder liquid supply device that supplies a concentrated magnetic powder liquid having a concentration higher than the magnetic powder concentration of the inspection liquid in the stirring tank to the stirring tank.
A liquid supply device for supplying only the solvent of the test liquid to the settling tank is provided.
The magnetic particle flaw detector according to any one of claims 1 to 6. The tank body is configured by being divided into the stirring tank and the settling tank by the partition wall, and further has a communication pipe that communicates the bottom of the stirring tank with the bottom of the settling tank.
The magnetic particle flaw detector according to any one of claims 1 to 7. In a magnetic particle flaw detection method in which an inspection object containing magnetic powder stored in a test liquid tank is used to detect a flaw.
The test liquid tank is
With a bottomed tubular tank body
A partition wall having a gap between the bottom wall of the tank body and partitioning the inside of the tank body into a stirring tank for storing the test solution in a stirred state and a settling tank for storing the test solution in a stationary state. Have and
The step of magnetizing the object to be inspected and
A step of spraying the test solution in the stirring tank onto the object to be inspected,
A step of spraying the test solution on the upper part of the settling tank onto the object to be inspected,
A magnetic particle inspection method comprising a step of collecting the test liquid sprayed on the object to be inspected and returning the test liquid to the test liquid tank.

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