Magnetic particle inspection device

Abstract

To provide a magnetic particle testing device that can perform flaw detection with relatively high accuracy. [Solution] The magnetic particle inspection apparatus 1 of this invention is used for inspecting defects in an object IS, and comprises magnetizers 12a to 12d for magnetizing the object IS, a movable liquid injection unit 13 that moves along the outer surface Se of the object IS and injects magnetic particle liquid from around the object IS toward the outer surface Se of the object IS, and a movable gas injection unit 14 that follows the movement of the liquid injection unit 13 and moves along the outer surface Se of the object IS and injects gas from around the object IS toward the location on the outer surface Se of the object IS toward the location on the outer surface Se of the object I toward which the magnetic particle liquid has adhered.

Description

Technical Field

[0001] This invention relates to a magnetic particle flaw detector used for flaw detection of inspected products.

Background Art

[0002] Magnetic particle flaw detection uses magnetic particles to detect flaws and other defects in inspected products such as ferromagnetic materials, and is widely used as one of the non-destructive inspections that can be performed quickly and with high precision.

[0003] Generally, in magnetic particle flaw detection, the inspected product is magnetized, and magnetic particles are attached to the outer surface of the inspected product using, for example, a magnetic particle liquid in which magnetic particles are dispersed in a liquid. The magnetic particles attached to the outer surface of the inspected product form a magnetic particle pattern on the outer surface, and leakage magnetic fluxes and the like caused by defects appear in such a magnetic particle pattern. Therefore, by observing the magnetic particle pattern on the outer surface, it is possible to detect the presence or absence of defects, their shape, size, etc. in the inspected product.

[0004] As related technology, for example, Patent Document 1 describes "a pipe vertical movement device including an inspection liquid tank for storing an inspection liquid composed of a magnetic particle liquid, a pipe receiver for receiving a pipe, and a pipe receiver vertical movement device for immersing the pipe receiver in the inspection liquid in the inspection liquid tank, and an electrode movement device for moving both electrodes that contact both ends of the pipe in the inspection liquid and conduct electricity to the pipe to both ends of the pipe, magnetizing the pipe in the inspection liquid, and forming a magnetic particle pattern on the welded defect part", a pipe magnetic particle flaw detector.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Incidentally, it is sometimes undesirable to repeatedly use magnetic particle liquid for magnetic particle testing. In this case, instead of immersing the object to be inspected in the magnetic particle liquid as described in Patent Document 1, it is possible to reduce the amount of magnetic particle liquid used per test by spraying the magnetic particle liquid onto the outer surface of the object to be inspected.

[0007] On the other hand, when magnetic powder liquid is sprayed onto the outer surface of the object under inspection, uneven adhesion of the magnetic powder liquid may occur on the outer surface of the object. This reduces the accuracy of flaw detection based on observation of the magnetic powder pattern on the outer surface.

[0008] This invention addresses the issues described above, and its objective is to provide a magnetic particle inspection device that can perform flaw detection with relatively high accuracy. [Means for solving the problem]

[0009] The magnetic particle flaw detection apparatus of this invention is used for flaw detection of an object to be inspected, and comprises a magnetizer for magnetizing the object to be inspected, a movable liquid spray unit that moves along the outer surface of the object to be inspected and sprays magnetic particle liquid from around the object to the outer surface of the object to be inspected, and a movable gas spray unit that moves along the outer surface of the object to be inspected, following the movement of the liquid spray unit, and sprays gas from around the object to the areas on the outer surface of the object to which the magnetic particle liquid has adhered.

[0010] The object to be inspected may have a hollow or solid rod shape, in which case it is preferable that the liquid injection unit and the gas injection unit each have a ring shape surrounding the object to be inspected and are movable in the longitudinal direction of the object to be inspected.

[0011] In the magnetic particle testing apparatus described above, it is preferable that the object to be inspected is positioned such that its longitudinal direction is inclined with respect to the horizontal direction or is in the vertical direction.

[0012] Preferably, the magnetizer has a pair of electrodes positioned at each end of the rod-shaped object under inspection, which generate a magnetic flux in the circumferential direction of the rod-shaped object under inspection by passing a direct current through it, and a coil positioned around the rod-shaped object under inspection, which generates a magnetic flux in the radial direction of the rod-shaped object under inspection by passing an alternating current through it.

[0013] Preferably, the above-described magnetic particle inspection apparatus further includes an image processing apparatus for processing an image of a magnetic particle pattern formed by the adhesion of magnetic particles to the outer surface of the object to be inspected.

[0014] In this case, it is preferable that the magnetic particle inspection device described above includes a liquid injection unit for injecting unused magnetic particle liquid as the liquid injection unit. [Effects of the Invention]

[0015] According to the magnetic particle flaw detection apparatus of this invention, flaw detection can be performed with relatively high accuracy. [Brief explanation of the drawing]

[0016] [Figure 1] This is a schematic diagram showing a magnetic particle testing apparatus according to one embodiment of the present invention. [Figure 2] This block diagram shows an example of an image processing device that can be included in the magnetic particle testing apparatus shown in Figure 1. [Modes for carrying out the invention]

[0017] Embodiments of this invention will be described in detail below with reference to the drawings. The magnetic particle inspection apparatus 1 shown in Figure 1 is used for inspecting defects in the IS of an object under inspection using magnetic particles.

[0018] The magnetic particle testing apparatus 1 can target various inspected objects (IS) as long as they are capable of magnetic particle testing. Typical inspected objects (IS) include metal parts or products made of ferromagnetic materials, such as automotive parts like rack bars. The material of the inspected object (IS) is, for example, steel, particularly carbon steel for machine structures as specified in JIS G4051 (2016). Here, we will explain in detail the case of inspected objects (IS) that have a hollow or solid rod shape, including cylinders and rods, as an example, but inspected objects (IS) are not limited to these.

[0019] This magnetic particle inspection apparatus 1 generally includes a magnetic particle adhesion apparatus 11 and a magnetic particle liquid supply apparatus 21 as shown in Figure 1, and an image processing apparatus as shown in Figure 2. The magnetic particle adhesion apparatus 11 is used to adhere magnetic particle liquid to the outer surface Se of the object IS under inspection, and magnetic particle liquid is supplied to the magnetic particle adhesion apparatus 11 from the magnetic particle liquid supply apparatus 21. The image processing apparatus is at least partially incorporated inside the magnetic particle adhesion apparatus 11 or provided outside the magnetic particle adhesion apparatus 11, and processes images of the magnetic particle pattern formed on the outer surface Se of the object IS under inspection by the adhesion of magnetic particles in the magnetic particle adhesion apparatus 11.

[0020] As shown in Figure 1, the magnetic particle adhesion device 11 includes magnetizers 12a to 12d for magnetizing the object IS under inspection, a liquid injection unit 13 for injecting magnetic particle liquid from around the object IS towards the outer surface Se of the object IS under inspection, and a gas injection unit 14 for injecting gas from around the object IS towards the outer surface Se of the object IS under inspection. The liquid injection unit 13 and the gas injection unit 14 are movable, each driven by a drive force from a drive source (not shown), and can inject magnetic particle liquid or gas while moving along the outer surface Se of the object IS under inspection. The magnetic particle inspection device 1 only needs to include at least the magnetic particle adhesion device 11 (i.e., magnetizers 12a to 12d, liquid injection unit 13, and gas injection unit 14), and this magnetic particle adhesion device 11 is sometimes referred to as the magnetic particle inspection device 1.

[0021] In such a magnetic powder adhering device 11, the test piece IS can be magnetized using magnetizers 12a to 12d, and the magnetic powder liquid can be sprayed from the surrounding liquid spraying part 13 toward the outer surface Se of the test piece IS. Thereby, it is possible to adhere the magnetic powder liquid to the outer surface Se of the test piece IS.

[0022] However, when the magnetic powder liquid is sprayed from the liquid spraying part 13 onto the outer surface Se of the test piece IS, due to the occurrence of so-called liquid dripping on the outer surface Se or the like, there may be a location where the adhesion of the magnetic powder liquid becomes uneven on the outer surface Se of the test piece IS. The uneven adhesion of the magnetic powder liquid on the outer surface Se of the test piece IS may subsequently inhibit accurate processing when, for example, processing an image of the magnetic powder pattern on the outer surface Se using an image processing device, and may reduce the flaw detection accuracy of the test piece IS.

[0023] To address this, in this embodiment, the gas injection part 14 is configured to move following the movement of the liquid injection part 13 at a position close to the liquid injection part 13, for example, and to be able to inject gas toward the location where the magnetic powder liquid has adhered to the outer surface Se of the test piece IS. According to this, after the magnetic powder liquid is sprayed from the liquid spraying part 13 and adheres to the outer surface Se of the test piece IS, gas is injected from the gas injection part 14 to the location where the magnetic powder liquid has adhered, thereby eliminating the liquid dripping of the magnetic powder liquid on the outer surface Se and making the adhesion amount or state of the magnetic powder liquid on the outer surface Se uniform. As a result, when flaw detection of the test piece IS is performed based on the magnetic powder pattern formed on the outer surface Se of the test piece IS, the flaw detection accuracy is significantly improved. This is particularly prominent when automatically observing and processing the magnetic powder pattern with an image processing device without manual intervention.

[0024] It is preferable that the gas injection unit 14 is moved in conjunction with the movement of the liquid injection unit 13. Furthermore, the gas injection unit 14 can be moved so as to maintain a position at a constant distance from the liquid injection unit 13. Additionally, by positioning the gas injection unit 14 behind the liquid injection unit 13 in the direction of movement (for example, above in the vertical direction), gas can be injected from the gas injection unit 14 immediately after the magnetic powder liquid injected from the liquid injection unit 13 adheres to the outer surface Se, resulting in more uniform adhesion of the magnetic powder liquid to the outer surface Se.

[0025] In a magnetic powder deposition apparatus 11 for inspected objects IS having a hollow or solid rod shape, it is preferable that the liquid injection section 13 and the gas injection section 14 each have a ring shape, such as an annular ring, surrounding the inspected object IS, as shown in Figure 1. In this case, the ring-shaped liquid injection section 13 and gas injection section 14 can be provided with multiple injection ports at equal intervals in the circumferential direction on the inner surface facing the inspected object IS, which is located on the inside. This allows the magnetic powder liquid or gas to be uniformly injected over the entire circumference of the outer surface Se of the inspected object IS.

[0026] Furthermore, it is preferable that the ring-shaped liquid injection section 13 and the gas injection section 14 are configured to be movable along the outer surface Se of the object IS under inspection in the longitudinal direction (vertical direction in Figure 1). In this way, the magnetic powder liquid or gas can be injected over the entire longitudinal direction of the outer surface Se of the object IS under inspection.

[0027] The direction of injection of magnetic liquid from the liquid injection unit 13 and the direction of injection of gas from the gas injection unit 14 can be in the radial or radial direction (perpendicular to the outer surface Se) of the rod-shaped workpiece IS, but they may also be slightly inclined to one side of the longitudinal direction with respect to the radial direction (for example, downward in the vertical direction or forward in the direction of movement). Although not shown in the figures, when dealing with a rod-shaped workpiece whose outer diameter changes along its longitudinal direction, the liquid injection unit may be controlled to change the injection flow rate of magnetic liquid as it passes around the part where the outer diameter changes. For example, the injection flow rate of magnetic liquid can be increased on the outer surface of a part where the outer diameter is relatively larger than on the outer surface of a part where the outer diameter is relatively smaller. In addition to or instead of this, the liquid injection unit may be controlled to change its moving speed as it passes around a part where the outer diameter changes.

[0028] The magnetic powder liquid sprayed from the liquid injection unit 13 can be a liquid in which magnetic powder is dispersed in water or other liquid. Known magnetic powders containing austenitic stainless steel, aluminum alloys, titanium alloys, and copper alloys can be used. Fluorescent magnetic powders that emit light upon irradiation with light of a specific wavelength (such as black light with a wavelength shorter than 400 nm) are particularly preferred. The gas sprayed from the gas injection unit 14 is not particularly limited, but air can be easily used. However, the gas may be an inert gas such as nitrogen.

[0029] The orientation of the rod-shaped object IS to be inspected may be such that its longitudinal direction coincides with the horizontal direction parallel to the installation surface of the magnetic powder adhesion device 11, but it is preferable that it be inclined diagonally with respect to the horizontal direction, or coincides with the vertical direction. This suppresses circumferential dripping of the rod-shaped object IS to be inspected. Preferably, as shown in Figure 1, the rod-shaped object IS to be inspected is placed upright in the magnetic powder adhesion device 11 and supported so that the rod-shaped object IS extends along the vertical direction. In this case, longitudinal dripping of the magnetic powder liquid that may occur can be effectively eliminated by the injection of gas from the gas injection unit 14, as described above.

[0030] When the rod-shaped object IS to be inspected is positioned such that its longitudinal direction coincides with the inclined direction relative to the horizontal or the vertical direction, it is preferable to sequentially move the liquid injection unit 13 and the gas injection unit 14 from the upper vertical side downwards while injecting the magnetic powder liquid or gas. This is because it makes it easier to eliminate dripping of the magnetic powder liquid in the longitudinal direction.

[0031] The magnetizers 12a to 12d in the magnetic powder deposition device 11 may specifically consist of a pair of electrodes 12a, 12b, and / or at least one coil 12c, 12d.

[0032] When a rod-shaped object under inspection IS is used, a pair of electrodes 12a and 12b can be placed on the respective ends Pe1 and Pe2 of the object under inspection IS. By connecting such electrodes 12a and 12b to a power supply 12e and applying a DC current to the object under inspection IS, a magnetic flux can be generated that is oriented along the circumferential direction of the rod-shaped object under inspection IS.

[0033] Furthermore, in the case of a rod-shaped object under inspection IS, one or more coils 12c and 12d, two in the illustrated embodiment, can be provided surrounding the rod-shaped object under inspection IS. The coils 12c and 12d can be constructed by winding a conductor in a spiral shape. When alternating current is passed through each coil 12c and 12d from the respective power sources 12f and 12g, a magnetic flux can be generated therein, oriented along the radial direction of the rod-shaped object under inspection IS.

[0034] It is preferable that not only the liquid injection unit 13 and gas injection unit 14 mentioned above, but also the coils 12c and 12d, be movable along the outer surface Se or longitudinal direction of the workpiece IS under inspection. The placement of the coils 12c and 12d in the longitudinal direction of the workpiece IS is not limited to this, but in Figure 1, the coils 12c and 12d are placed between the upper vertical electrode 12a and the gas injection unit 14, and between the liquid injection unit 13 and the lower vertical electrode 12b, respectively, in the longitudinal direction.

[0035] Furthermore, when removing the item IS to be inspected from the magnetic powder deposition device 11, electrodes 12a and 12b can be moved away from the ends Pe1 and Pe2 of the item IS to be inspected, and the liquid injection unit 13, gas injection unit 14, and coils 12c and 12d can be moved to positions away from the periphery of the item IS to be inspected.

[0036] Of the magnetizers 12a to 12d, if at least one of the electrodes 12a and 12b and the coils 12c and 12d is present, particularly electrodes 12a and 12b, the object IS under inspection can be magnetized, and magnetic particle testing can be performed. On the other hand, in order to accommodate the object IS under inspection, the nature of its defects, and various other conditions, it is sometimes preferable to provide not only electrodes 12a and 12b but also coils 12c and 12d, as shown in the illustrated embodiment. By using coils 12c and 12d that can move along the longitudinal direction of the object IS under inspection, together with electrodes 12a and 12b, it becomes possible to change the magnetic flux at a predetermined position in the longitudinal direction of the object IS under inspection to a desired direction, thereby improving the accuracy of flaw detection for defects extending in various directions. The coils 12c and 12d may be operated in conjunction with electrodes 12a and 12b. Electrodes 12a, 12b and coils 12c, 12d can be activated before or during the supply of magnetic powder liquid to the outer surface of the object IS under inspection.

[0037] Incidentally, the magnetic powder liquid supply device 21, which supplies magnetic powder liquid to the liquid injection section 13 of the magnetic powder adhesion device 11, may include a storage tank 22 for storing magnetic powder liquid, and piping 23 having a magnetic powder liquid flow path 23a for guiding the magnetic powder liquid from the storage tank 22 to the liquid injection section 13 of the magnetic powder adhesion device 11. If necessary, a stirrer 22a may be provided in the storage tank 22 to eliminate the sedimentation of magnetic powder in the magnetic powder liquid ML stored therein.

[0038] The magnetic powder liquid ML in the storage tank 22 may be diluted with a diluent such as water and supplied to the magnetic powder adhesion device 11. In this case, in addition to the magnetic powder liquid flow path 23a, the piping 23 may also be provided with a diluent flow path 23b connected to a diluent supply source (not shown) for carrying the diluent, and a confluence flow path 23c through which the diluted magnetic powder liquid ML flows. For example, by placing a Venturi tube at the confluence point 23d of the magnetic powder liquid flow path 23a and the diluent flow path 23b, and connecting the magnetic powder liquid flow path 23a to the portion where the cross-sectional area of ​​the Venturi tube becomes smaller, the magnetic powder liquid in the storage tank 22 can be guided to the magnetic powder liquid flow path 23a using a negative pressure suction method.

[0039] Valves 23e to 23g for opening / closing or flow rate adjustment may be placed in each of the magnetic powder liquid flow path 23a, the diluent flow path 23b, and the confluence flow path 23c. By operating valves 23e to 23g, the diluent can be supplied to the magnetic powder adhesion device 11 on its own, and the diluent can also be used as a cleaning solution for removing magnetic powder from the inspected item IS. In addition, the piping 23 may be equipped with an air purge unit controlled by a sequencer, solenoid, check valve, etc., to eliminate the accumulation or adhesion of magnetic powder when the magnetic powder liquid ML is not flowing through it.

[0040] After the magnetic powder liquid is supplied from the magnetic powder liquid supply device 21 and sprayed onto the outer surface Se of the object IS under inspection by the magnetic powder adhesion device 11, a residual portion that does not adhere to the outer surface Se may remain. Such residual magnetic powder liquid can be recovered from the magnetic powder adhesion device 11, but it may not be desirable to reuse it for subsequent magnetic particle testing. For example, when observing or processing the magnetic particle pattern with an image processing device described later, if the magnetic powder liquid used for multiple magnetic particle testing tests is used, the image may change due to a decrease in the concentration or deterioration of the magnetic powder liquid, potentially leading to different inspection results. In such cases, it is preferable to discard the residual magnetic powder liquid and spray unused magnetic powder liquid from the liquid spray unit 13. Furthermore, since the magnetic powder liquid is discarded after each use, it is desirable to minimize the amount used in magnetic particle testing. In this embodiment, since the magnetic powder liquid is sprayed from the liquid spray unit 13, the amount of magnetic powder liquid used can be significantly reduced compared to the case where the object under inspection is immersed in the magnetic powder liquid as described in Patent Document 1.

[0041] After the magnetic powder liquid has been applied to the outer surface Se of the product IS under inspection using the magnetic powder application device 11, defects in the product IS under inspection are detected using the magnetic powder. Here, a magnetic powder pattern is formed on the outer surface Se of the product IS under inspection by the magnetic powder applied to it, and defects in the product IS under inspection can be detected by observing this magnetic powder pattern.

[0042] Observation of the magnetic particle pattern on the outer surface Se of the object IS under inspection can be performed by visual inspection by an operator. On the other hand, from the viewpoint of improving inspection efficiency and accuracy, suppressing cost increases due to labor costs, and suppressing variations in inspection accuracy due to differences in the inspection capabilities of operators, it is desirable to use an image processing device to observe or process the magnetic particle pattern on the outer surface Se. For this reason, the magnetic particle testing apparatus 1 preferably includes an image processing device that processes images of the magnetic particle pattern on the outer surface Se of the object IS under inspection.

[0043] When using an image processing device, even slight dripping of the magnetic powder liquid on the outer surface Se of the object IS under inspection, which is not visible to the naked eye, can significantly affect the processing results of the image processing device. In contrast, in this embodiment, as described above, the dripping on the outer surface Se can be effectively eliminated by the injection of gas from the gas injection unit 14 that moves in conjunction with the liquid injection unit 13, making it possible to perform flaw detection with high accuracy even when using an image processing device.

[0044] The image processing device that the magnetic particle flaw detection apparatus 1 may be equipped with, as illustrated in Figure 2, may include an acquisition unit that acquires an image including the magnetic particle pattern of the outer surface Se of the object IS under inspection, a processing unit that processes the image acquired by the acquisition unit, a display unit such as a display or touch panel that displays the results of the processing by the processing unit, and a storage unit that stores necessary information.

[0045] The acquisition unit only needs to be capable of acquiring image information of the outer surface Se of the object IS under inspection. For example, it may acquire image information that has already been captured via wired or wireless communication or a storage medium. In this case, the image of the outer surface Se of the object IS under inspection may be taken manually. Alternatively, the acquisition unit may use an imaging device such as a camera to photograph the outer surface Se of the object IS under inspection. If the acquisition unit has an imaging device, that imaging device may be located either inside or outside the magnetic powder deposition device 11. Accordingly, after the magnetic powder deposition of the magnetic powder onto the outer surface Se of the object IS under inspection is completed in the magnetic powder deposition device 11, the outer surface Se is photographed either while the object IS under inspection is still located inside the magnetic powder deposition device 11 or after it has been removed from the inside.

[0046] The processing unit consists of a processor, RAM (Random Access Memory), and ROM (Read Only Memory), and performs various processes such as image processing by executing control programs recorded in the ROM or storage unit with the processor. The storage unit consists of an HDD (Hard Disk Drive) or flash memory, and stores various data and programs. Data and signals can be sent and received between the processing unit and its components, such as the acquisition unit, display unit, and storage unit, via a bus.

[0047] As described above, the magnetic particle inspection apparatus 1 is equipped with a movable liquid injection unit 13 and a movable gas injection unit 14 that can move in conjunction with it, thereby enabling inspection with relatively high accuracy. [Explanation of Symbols]

[0048] 1 Magnetic particle flaw detection equipment 11 Magnetic particle attachment device 12a, 12b electrode (magnetizer) 12c, 12d coils (magnetizers) 12e~12g power supply 13 Liquid injection part 14. Gas injection section 21 Magnetic powder liquid supply device 22 Storage tanks 22a Agitator 23 Piping 23a Magnetic powder liquid flow path 23b Dilution solution channel 23c Confluence channel 23d Junction 23e~23g valve IS inspected product ML magnetic powder liquid Pe1, Pe2: End Se external surface

Claims

1. A magnetic particle testing device used for inspecting defects in an object under inspection, A magnetizer for magnetizing the item to be inspected, A movable liquid spray unit moves along the outer surface of the object to be inspected and sprays magnetic powder liquid from around the object to be inspected toward the outer surface of the object to be inspected, A movable gas injection unit moves along the outer surface of the object under inspection, following the movement of the liquid injection unit, and injects gas from around the object under inspection toward the areas on the outer surface of the object under inspection where the magnetic powder liquid has adhered. A magnetic particle testing device equipped with a magnetic particle testing system.

2. The item to be inspected has a hollow or solid rod shape, The magnetic particle testing apparatus according to claim 1, wherein the liquid injection unit and the gas injection unit each have a ring shape surrounding the object to be inspected and are movable in the longitudinal direction of the object to be inspected.

3. The magnetic particle testing apparatus according to claim 2, wherein the object to be inspected is arranged such that its longitudinal direction is inclined with respect to the horizontal direction or is in the vertical direction.

4. The magnetizer, A pair of electrodes are positioned at each end of the rod-shaped object under inspection, and a direct current is passed through the object under inspection to generate a magnetic flux in the circumferential direction of the rod-shaped object under inspection. A coil is positioned around the rod-shaped object under inspection and generates a magnetic flux in the radial direction of the rod-shaped object under inspection when an alternating current is passed through it. A magnetic particle testing apparatus according to claim 2, having the following features.

5. The magnetic particle inspection apparatus according to any one of claims 1 to 4, further comprising an image processing apparatus for processing an image of a magnetic particle pattern formed by the adhesion of magnetic particles to the outer surface of the object to be inspected.

6. The magnetic particle inspection apparatus according to claim 5, further comprising a liquid injection unit for injecting unused magnetic particle liquid as the liquid injection unit.

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