Liquid penetrant inspection method and liquid penetrant inspection device

Abstract

To provide a liquid penetrant inspection method and a liquid penetrant inspection device which achieve reduction in time required for a heating process more than before.SOLUTION: A liquid penetrant inspection method includes a heating step 40, a penetration step 31, a cooling step 41, a cleaning step 32, a development step 33, and an observation step 34 in sequential order. A liquid penetrant inspection device for implementing the liquid penetrant inspection method includes heating means capable of executing the heating step 40. The heating means can inject superheated steam 59 by a boiling water tank 50 and a steam injection part 51 and also high-temperature hot air 60 by a hot air injection part 58, to a surface 11 of an inspected object 10.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present invention relates to a penetrant inspection method and apparatus, and particularly to a method and apparatus for causing a penetrant to penetrate into a defect on the surface of an object to be inspected.

Background Art

[0002] Conventionally, as one of non-destructive inspection methods for detecting fine opening defects and the like on the surface of products made of non-magnetic materials such as aluminum, titanium, austenitic stainless steel, and ceramics, which are manufactured as industrial materials, a penetrant inspection method is known.

[0003] The conventionally known penetrant inspection method includes a penetration step of applying a penetrant to the surface of an object to be inspected and causing the penetrant to penetrate into the opening defects existing on the surface of the object to be inspected; next, a cleaning step of removing the excess penetrant remaining and adhering to the surface of the object to be inspected without penetrating into the defect portion with a cleaning liquid so that the penetrant remains only in the defect portion; next, after the cleaning liquid is dried, a uniform thin layer of a developer is formed on the surface of the object to be inspected, and a developing step of sucking out the penetrant penetrating into the defect portion to expose a defect indication pattern on the layer surface; and then an observation step of confirming the defect indication pattern under visible light or under irradiation with ultraviolet light. And before performing the penetration step, if there is oil stain or the like on the surface of the object to be inspected, a pre-cleaning step of cleaning the surface with an organic solvent or the like is performed. Note that as the penetrant, a non-volatile and highly penetrative liquid obtained by dissolving a red dye or a fluorescent dye in a petroleum-based mixed solvent, an aromatic solvent, etc. and adding a plasticizer, a surfactant, etc. is usually used. Also, as the cleaning liquid for cleaning the excess penetrant, a method using an organic solvent that dissolves the penetrant or water is known.

[0004] In Patent Document 1, in a penetrant testing, after a cleaning process of removing excess penetrant by using water is completed, heating of the surface of a test piece in a drying process is performed by induction heating that causes self-heating by resistance loss of eddy current induced near the surface layer portion of the test piece. Although this is excellent as a drying process, there still remained problems regarding shortening of the time required for the process of infiltrating the penetrant, etc.

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] Thus, in the conventionally known penetrant testing method, in the penetration step of infiltrating the penetrant into the open defect portions present on the surface of the object to be inspected, a long penetration time was required to sufficiently infiltrate the penetrant into the open defect portions. Due to the long penetration time in the penetration step, this penetration step became a bottleneck and the working efficiency of the line decreased, and the fact that a vast space was required for the penetration step was a problem. In the case of a billet or the like where the object to be inspected is relatively large, a space for storing a plurality of billets for the penetration step is required. Therefore, in a factory with a large production volume, etc., it is necessary to secure a vast space for storing a large number of large billets, and this was also a problem. Therefore, the conventional penetrant testing method had the problem that it was practically impossible to target parts with a large production volume or parts that had to be inspected in real time. The present invention provides a penetrant testing method for solving these problems and a penetrant testing device used therefor.

Means for Solving the Problems

[0007] Therefore, the penetrant flaw detection method of the present invention sequentially includes a penetration step of applying a penetrant to the object to be inspected, a cleaning step of removing the penetrant on the surface of the object to be inspected, and an observation step of observing the indication pattern. In the penetrant flaw detection method, the penetrant flaw detection method further includes a heating step before the penetration step. The heating step is a step of sequentially performing an immersion step and a first reheating step. The immersion step is a step of immersing the object to be inspected in hot water at 90 degrees Celsius or higher in a hot water tank for within 30 seconds. The first reheating step is a step of heating the surface of the object to be inspected with superheated steam immediately after at least a part of the object to be inspected is withdrawn from the hot water in the hot water tank. It is characterized by this.

[0008] Further, the penetrant flaw detection method of the present invention sequentially includes a penetration step of applying a penetrant to the object to be inspected, a cleaning step of removing the penetrant on the surface of the object to be inspected, and an observation step of observing the indication pattern. In the penetrant flaw detection method, the penetrant flaw detection method further includes a heating step before the penetration step. The heating step is a step of sequentially performing an immersion step and a second reheating step. The immersion step is a step of immersing the object to be inspected in hot water at 90 degrees Celsius or higher in a hot water tank for within 30 seconds. The second reheating step is a step of heating the surface of the object to be inspected with hot air at 100 degrees Celsius or higher immediately after at least a part of the object to be inspected is withdrawn from the hot water in the hot water tank. It is characterized by this.

[0009] In the penetrant flaw detection method that sequentially includes a penetration step of applying a penetrant to the object to be inspected, a cleaning step of removing the penetrant on the surface of the object to be inspected, and an observation step of observing the indication pattern, the penetrant flaw detection method further includes a heating step before the penetration step. The heating step is a step of sequentially performing an immersion step and a third reheating step. The immersion step is a step of immersing the object to be inspected in hot water at 90 degrees Celsius or higher in a hot water tank for within 30 seconds. The third reheating step is a step of heating the surface of the object to be inspected with superheated steam for 1 to 4 seconds immediately after at least a part of the object to be inspected is withdrawn from the hot water in the hot water tank, and then heating the part of the surface of the object to be inspected heated with superheated steam with hot air at 100 degrees Celsius or higher for 1 to 5 seconds immediately after that. It is characterized by this.

[0010] Moreover, the penetrant flaw detection device of the present invention is a penetrant flaw detection device including a heating means, a penetrating means, a cleaning means, and an observation means, wherein the heating means is characterized by including a hot water tank and a steam injection unit capable of injecting superheated steam.

[0011] Moreover, the present invention is a penetrant flaw detection device including a heating means, a penetrating means, a cleaning means, and an observation means, wherein the heating means is characterized by including a hot water tank and a hot air injection unit capable of injecting high-temperature hot air.

[0012] Moreover, in the penetrant flaw detection device of the present invention, the hot water tank is characterized by including a hot water injection unit capable of making hot water convect inside.

[0013] The hot water tank is provided with a lid, and the lid is provided with a steam-resistant sealing material.

Advantages of the Invention

[0014] The penetrant flaw detection method of the present invention is a penetrant flaw detection method sequentially including a penetration step of applying a penetrant to an object to be inspected, a cleaning step of removing the penetrant on the surface of the object to be inspected, and an observation step of observing an indication pattern. The penetrant flaw detection method further includes a heating step before the penetration step. The heating step is a step of sequentially performing an immersion step and a first reheating step. The immersion step is a step of immersing the object to be inspected in hot water at 90 degrees Celsius or higher in a hot water tank for within 30 seconds. The first reheating step is a step of heating the surface of the object to be inspected with superheated steam immediately after at least a part of the object to be inspected is withdrawn from the hot water in the hot water tank. Therefore, it is possible to provide a penetrant flaw detection method capable of making the penetrant penetrate into the opening defect part in a short time.

[0015] Also, in the penetrant testing method of the present invention, in the penetrant testing method that sequentially includes a penetration step of applying a penetrant to the object to be inspected, a cleaning step of removing the penetrant on the surface of the object to be inspected, and an observation step of observing the indication pattern, the penetrant testing method further includes a heating step before the penetration step. The heating step is a step of sequentially performing an immersion step and a second reheating step. The immersion step is a step of immersing the object to be inspected in hot water at 90 degrees Celsius or higher in a hot water tank for 30 seconds or less. The second reheating step is a step of heating the surface of the object to be inspected with hot air at 100 degrees Celsius or higher immediately after at least a part of the object to be inspected is withdrawn from the hot water in the hot water tank. Therefore, a penetrant testing method capable of allowing the penetrant to penetrate into the open defect portion in a short time can be provided.

[0016] Also, the penetrant testing method of the present invention, in the penetrant testing method that sequentially includes a penetration step of applying a penetrant to the object to be inspected, a cleaning step of removing the penetrant on the surface of the object to be inspected, and an observation step of observing the indication pattern, the penetrant testing method further includes a heating step before the penetration step. The heating step is a step of sequentially performing an immersion step and a third reheating step. The immersion step is a step of immersing the object to be inspected in hot water at 90 degrees Celsius or higher in a hot water tank for 30 seconds or less. The third reheating step is a step of heating the surface of the object to be inspected with superheated steam for 1 to 4 seconds immediately after at least a part of the object to be inspected is withdrawn from the hot water in the hot water tank, and then heating the portion of the surface of the object to be inspected heated with superheated steam with hot air at 100 degrees Celsius or higher for 1 to 5 seconds. Therefore, a penetrant testing method capable of allowing the penetrant to penetrate into the open defect portion in a short time can be provided.

[0017] Also, the penetrant testing device of the present invention, also, the penetrant testing device of the present invention is a penetrant testing device provided with a heating means, a penetration means, a cleaning means, and an observation means, characterized in that the heating means includes a hot water tank and a steam injection portion capable of injecting superheated steam. Therefore, a penetrant testing device capable of allowing the penetrant to penetrate into the open defect portion in a short time can be provided.

[0018] Furthermore, the penetrant flaw detection device of the present invention is a penetrant flaw detection device provided with a heating means, a penetrating means, a cleaning means, and an observation means, wherein the heating means is characterized by including a hot water tank and a hot air injection unit capable of injecting high-temperature hot air, so that a penetrant flaw detection device capable of causing a penetrant to penetrate into an opening defect portion in a short time can be provided.

[0019] Also, in the penetrant flaw detection device of the present invention, the hot water tank is characterized by including a hot water injection unit capable of causing convection of hot water inside, so that the surface of the object to be inspected can be heated uniformly and without unevenness in a shorter time in the heating process, and a penetrant flaw detection device capable of causing a penetrant to penetrate into an opening defect portion in a short time can be provided.

[0020] Also, in the penetrant flaw detection device of the present invention, the hot water tank is provided with a lid, and the lid is provided with a steam-resistant sealing material, so that a penetrant flaw detection device capable of effectively preventing the steam in the hot water tank from escaping can be provided.

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Mode for Carrying Out the Invention

[0022] Hereinafter, with reference to the drawings, the details of the embodiments of the present invention will be described. First, the penetrant flaw detection method according to this embodiment will be described. FIG. 1 is a flowchart diagram of a conventional penetrant flaw detection method. FIG. 2 is a schematic cross-sectional view showing the state transition around the flaw 12 in the conventional penetrant flaw detection method, and the states transition in the order of (W), (X), (Y), and (Z). Among them, (W) represents the initial state before performing the penetration step 31. (X) represents the state immediately after applying the penetrant to the flaw 12 during the penetration step 31, (Y) represents the state around the flaw 12 when the penetration time has elapsed from the state of (X) during the penetration step 31, and (Z) represents the state around the flaw 12 after the cleaning step 32. FIG. 3 is a flowchart diagram of a penetrant flaw detection method as an example of an embodiment according to the present invention. FIG. 4 is a schematic cross-sectional view showing the state transition around the flaw 12 in the penetrant flaw detection method according to this embodiment, and the states transition in the order of (W), (X), (Y), and (Z). Among them, (W) represents the initial state before performing the penetration step 31. (X) represents the state immediately after applying the penetrant to the flaw 12 during the penetration step 31, (Y) represents the state around the flaw 12 when a time shorter than the conventional penetration time has elapsed from the state of (X) during the penetration step 31, and (Z) represents the state around the flaw 12 after the cleaning step 32. FIG. 5 is a flowchart diagram showing only the heating step 40 of the penetrant flaw detection method according to this embodiment and illustrating its content. FIG. 6 is a cross-section of the hot water tank 50 provided in the penetrant flaw detection apparatus according to this embodiment, shown in the drawing. FIG. 7(X) is a view showing the state immediately before immersion during the immersion step 42 of the hot water tank 50. For the convenience of explanation, only the cross-section of the hot water tank 50 is shown as being exposed. (Y) is a view showing the state during immersion during the immersion step 42 of the hot water tank 50 shown in FIG. 6, and similar to FIG. 7(X), it is a view shown with only the cross-section of the hot water tank 50 exposed for the convenience of explanation. FIG. 8(X) is a view showing the state during the first to third reheating steps 43, 44, and 45 immediately after the immersion step 42 is completed in this embodiment, and (Y) is a partial enlarged view showing a part of FIG. 8(X) enlarged. In the present disclosure, for the convenience of explanation, when simply referring to the upper side only, it refers to the upper side in FIGS. 7 and 8, and when simply referring to the lower side, it refers to the lower side in FIGS. 7 and 8.

[0023] The process shown in Fig. 1 is a flowchart diagram showing the process of the conventional penetrant testing method. In the conventional penetrant testing method, the penetration process 31, the cleaning process 32, the developing process 33, and the observation process 34 were sequentially performed. This will be described in detail together with the state around the defect 12 shown in Fig. 2. Each of the figures (W) to (Z) in Fig. 2 is an enlarged cross-sectional view showing the periphery of the defect 12 that occurred in the test object 10 and is the object of detection in the penetrant testing method. First, the state before the penetration process 31 shown in Fig. 1 is shown in Fig. 2(W). In the state of Fig. 2(W), the defect 12 has a defect opening 13 and a defect interior 14. And the defect 12 is formed in such a shape that it has a defect opening 13 on the surface 11 which is the surface of the test object 10.

[0024] Next, the penetration process 31 shown in Fig. 1 will be described in detail. The penetration process 31 is performed by applying the penetrant 21 to the surface 11 of the test object 10. As the application method, there are methods such as coating and immersion in the penetrant. As the penetrant 21 is used, a liquid composed of a composition in which a fluorescent dye or a red visible dye is dissolved in an oily solvent and further a surfactant is added to make it removable by water washing, or a solution in which a fluorescent dye or a red visible dye is dissolved in an oily solvent, etc.

[0025] In the penetration process 31, the state immediately after applying the penetrant 21 to the surface 11 is shown in Fig. 2(X). Since it is immediately after applying the penetrant 21 to the surface 11, the penetrant 21 has not entered the defect interior 14 which is inside the defect 12. In the conventional penetrant testing method, unless a certain long penetration time is passed after the penetration process 31, the penetrant 21 does not sufficiently enter from the defect opening 13 into the defect interior 14. The state after passing through this long penetration time is shown in Fig. 2(Y). In Fig. 2(Y), the penetrant 21 has sufficiently entered and penetrated the defect interior 14. However, since the penetrant 21 covers the surface 11, it is necessary to remove the penetrant 21 from the surface 11 by the cleaning process 32 shown in Fig. 1. Therefore, in the cleaning process 32, the cleaning liquid is applied to the surface 11 so as to wash away the penetrant 21 from, for example, the arrow direction in Fig. 2(Y). As a result, a transition occurs from the state of Fig. 2(Y) to the state of Fig. 2(Z).

[0026] Next, the state of Fig. 2(Z) will be described in detail. In the state of Fig. 2(Z), the penetrant 21 that filled the surface 11 of the object 10 to be inspected in the cleaning step 32 has been cleaned by the cleaning liquid, and the penetrant 21 has been removed. Although the penetrant 21 is removed from the surface 11, the penetrant 21 remains infiltrated in the defect interior 14.

[0027] Next, the developing step 33 will be described. First, in the state of Fig. 2(Z), the penetrant 21 remains only in the defect interior 14. In this state, since the defect 12 is fine, it is difficult to detect the presence of the penetrant 21 with the naked eye. Therefore, as a developer, a white inorganic fine powder or a dispersion of this in water or a solvent is applied to the surface 11 so as to form a uniform thin layer on the object to be inspected. Examples of the white inorganic fine powder include magnesium carbonate powder and calcium carbonate powder. Then, due to the uniform thin layer of the white inorganic fine powder formed on the surface 11, capillary action occurs, and the penetrant 21 in the defect interior 14 is sucked out, thereby forming a blister pattern (defect indication pattern). The defect opening 13 is enlarged and shown by this defect indication pattern, making it easy to detect with the naked eye.

[0028] Next is the observation step 34. In addition to the visual method, methods such as using a black light in a dark room after using a fluorescent penetrant and imaging an image with an imaging device or the like to observe the indication pattern are used.

[0029] Next, while showing FIGS. 3 and 4, the penetrant flaw detection method according to the present invention and the penetrant flaw detection apparatus using this method will be described in detail. The process shown in FIG. 3 is a flowchart showing the process of the penetrant flaw detection method as an example of an embodiment according to the present invention. Further, FIG. 4 is a cross-sectional view showing an enlarged view of the periphery of the defect 12, which is the object of detection in the penetrant flaw detection method, on the test object 10 in each of the figures (W) to (Z). First, different from the conventional method, the penetrant flaw detection method according to the present embodiment includes a heating step 40 shown in FIG. 3. In the heating step 40, heating is performed toward the surface 11 shown in FIG. 4(X) by heating means. The heating means for performing the heating step 40 includes a hot water tank 50, a steam injection unit 51, and a hot air injection unit 58. After immersing the test object in the hot water stored inside the hot water tank, while pulling up the test object 10 from the hot water tank, the superheated steam 59 is injected onto the surface 11 by the steam injection unit 51, or the hot air injection unit 58 is used to inject the high-temperature hot air 60 of 100 degrees or more onto the surface 11. The high-temperature hot air 60 can raise the temperature of the surface 11 and effectively dry the surface 11 when the temperature is 150 degrees to 250 degrees and the wind speed is 10 to 20 meters. By drying the surface 11, the penetrant can be effectively penetrated into the surface 11. By heating the surface 11 and the vicinity of the surface 16 by the heating means, in the test object 10 after the heating step 40 is performed, the air inside the defect 14 expands, and the penetrant 21 can be easily drawn in. Further, in the present disclosure, the superheated steam refers to steam having a steam temperature of 100 degrees or more.

[0030] While showing FIGS. 3 and 4, an example of the penetrant flaw detection method according to the embodiment of the present invention will be described in further detail. As an example of the penetrant flaw detection method of the embodiment of the present invention shown in FIG. 3, a heating step 40, a penetration step 31, a cooling step 41, a cleaning step 32, a developing step 33, and an observation step 34 are sequentially performed. Thus, in the penetrant flaw detection method according to this embodiment, first, the heating step 40 is performed. The heating step 40 is performed in the state of FIG. 4(W) which is the initial state. After this state, heating is performed on the surface 11 by heating means, and then the penetration step 31 is performed. In the heating step 40, it is preferable to heat the temperature of the surface 11 by 20 degrees Celsius or more in absolute temperature. This means that since the penetrant flaw detection test is usually at room temperature, it is heated from room temperature by 20 degrees Celsius or more. By heating in this way, the penetration time is significantly shortened. The specific flow of the heating step 40 will be described separately.

[0031] In the present disclosure, the penetration time refers to the time required from the end of the step of applying the penetrant 21 to the surface 11 of the test object 10 by the penetration step 31 until the penetrant 21 sufficiently penetrates into the defect interior 14 and reaches a state where it can be transferred to the next cleaning step 32 for the penetrant flaw detection test.

[0032] In the heating step 40, it is preferable to raise the absolute temperature of the surface 11 by 20 degrees Celsius or more, and it is more preferable to raise the absolute temperature of the surface 11 by 50 degrees Celsius or more by heating means. When the absolute temperature of the surface 11 is raised by 50 degrees Celsius or more by heating means in this way, in a penetrant flaw detection test of a billet or the like, for a defect of about 10 to 50 microns in size which is a relatively large defect, it is possible to reach a state where the penetrant 21 penetrates into the defect interior 14 to such an extent that the defect can be detected with a penetration time of about 5 to 10 seconds, which is preferable.

[0033] Regarding the penetration process 31 in the penetration flaw detection method according to the present embodiment shown in FIG. 3, it is performed by applying the penetrant 21 to the surface 11 of the object to be inspected 10. Then, it transitions to the state of FIG. 4(X). As a method for applying the penetrant 21, known methods such as coating with a spray or the like, or dipping in a penetrant tank of the penetrant 21 may be used. Examples of what is used for the penetrant 21 include a liquid composed of a composition in which a fluorescent dye or a red visible dye is dissolved in an oily solvent and a surfactant is further added to make it removable by water washing, or a liquid in which a fluorescent dye or a red visible dye is dissolved in an oily solvent, but other known ones may also be used.

[0034] In the penetration process 31, after applying the penetrant 21, without removing the penetrant 21 adhered to the surface 11, it does not move to the washing process 32 until the penetration time has elapsed. Thereby, the penetrant 21 penetrates into the defect interior 14. By passing through the heating process 40 of the penetration flaw detection method according to the present embodiment, this penetration time can be made shorter than usual. Specifically, what used to take 5 to 10 minutes or more becomes about 5 to 15 seconds. In terms of being able to sufficiently penetrate the penetrant 21 into the defect interior 14 even when the penetration time is shortened, it is preferable to use a heating means.

[0035] Next, the cooling process 41 shown in FIG. 3 will be described in detail. The cooling process 41 is preferably carried out during the penetration time after the penetration liquid 21 is applied in the penetration process 31. However, the cooling process 41 may not be provided. In that case, as another example of this embodiment, a penetration time during which the cooling process 41 is not carried out may be provided between the penetration process 31 and the cleaning process 32. As the specific content of the cooling process 41, after the penetration process 31, in the state of (X) in FIG. 4, it is carried out by blowing cold air, spraying normal-temperature water or cold water, etc. toward the vicinity of the surface 11 to which the penetration liquid 21 is attached. Thereby, a cooling effect is generated in which the surface 11 and the vicinity portion 16 of the surface are cooled. Due to the cooling effect, the air inside the defect 14 is also cooled and shrinks. As a result, the penetration liquid 21 is drawn into the defect 14. By performing the cooling process 41, such a cooling effect is generated, so the penetration time from after the cooling process 41 until shifting to the cleaning process 32 can be shortened. As factors of the cooling effect in which the vicinity of the surface 11 and the vicinity portion 16 of the surface are cooled, cooling from the inner part of the object 10 to be inspected and cooling by the penetration liquid 21 are also important together.

[0036] Next, the cleaning process 32 shown in FIG. 3 will be described. As shown in FIG. 4(Y), in the cleaning process 32, the penetration liquid 21 has sufficiently entered from the defect opening 13 into the defect 14. That is, the penetration liquid 21 has sufficiently penetrated into the defect 14. However, since the penetration liquid 21 covers the surface 11, it is necessary to remove it. Therefore, the penetration liquid 21 is removed from the surface 11 by the cleaning process 32 shown in FIG. 3. For this purpose, in the cleaning process 32, the cleaning liquid is applied to the surface 11 so as to wash away the penetration liquid 21 from, for example, the direction of the arrow in FIG. 4(Y). Thereby, a transition is made from the state of FIG. 4(Y) to the state of FIG. 4(Z).

[0037] Next, the developing process 33 will be described. First, the state shown in Fig. 4(Z) is a state where the penetrant 21 remains only inside the defect 14. In this state, it is difficult to detect the presence of the penetrant 21 with the naked eye. Therefore, as a developer, a white inorganic fine powder or a dispersion of this in water or a solvent is applied to the surface 11 so as to form a uniform thin layer on the object to be inspected. As the white inorganic fine powder, those known for use as developers such as magnesium carbonate powder and calcium carbonate powder may be used. Then, due to the uniform thin layer formed by the white inorganic fine powder on the surface 11, capillary action occurs, and the penetrant 21 inside the defect 14 is sucked out, thereby forming a sweat-like pattern (defect indication pattern). The defect opening 13 is enlarged and shown by this defect indication pattern, making it easy to detect with the naked eye and improving the detection accuracy at the same time.

[0038] However, in the penetrant inspection method of the present invention, the developing process 33 may not be provided and may be by known means such as the non-developing method. In the case of the non-developing method, the developing process 33 is not provided and the developer is not applied, and the indication pattern of the penetrant is observed as it is. For this reason, from the viewpoint of convenience of observation in the observation process 34, it is desirable to use a fluorescent penetrant, but it is not limited to this.

[0039] Next, regarding the observation process 34 shown in Fig. 3, known means such as a method using a black light in a dark room after using a fluorescent penetrant in addition to visual inspection, or a method of imaging and inspecting an image with an imaging device or the like are used to observe the indication pattern.

[0040] In addition to the heating means, a cleaning means and an observation means may be provided in the penetrant flaw detection device of the present invention. A cleaning means for performing a cleaning step 32 of removing the penetrant 21 from the object to be inspected 10 may be arranged. Further, as a subsequent step, a developing means for performing a developing step 33 and an observation means for performing an observation step 34 may be provided. However, since there is a non-developing method, the developing means may not be provided. As the cleaning means, it is preferable to have a mechanism for applying a cleaning liquid to the object to be inspected 10 by means such as spraying or coating. As the developing means, a spraying or coating device for applying a developer or a developing liquid to the surface 11 of the object to be inspected 10 is suitable. As the observation means, it is preferably composed of an imaging means for imaging a still image or a moving image video, a recording medium, a display medium, etc. However, for each of them, publicly known ones can be appropriately used.

[0041] In the heating step 40, the surface vicinity part 16 is first heated. Then, thereafter, the air on the surface 11 adjacent to the surface vicinity part 16 and the air in the defect interior 14 are heated. When the air is heated and in the penetrant step 31 shown in FIG. 3 and in the state of FIG. 4(X), the air remaining in the defect interior 14 is heated. This heated air is cooled by the cooling effect of cooling from the inner part of the object to be inspected 10, cooling by the penetrant 21, and cooling by the cooling step 41 during the penetrant time, and contracts. When the air in the defect interior 14 contracts, a force acts to draw the penetrant 21 into the defect interior 14, and the penetrant time for the penetrant 21 to penetrate into the defect interior 14 is shortened.

[0042] Next, while showing FIG. 5, the content of the heating step 40 will be described in more detail. As shown in FIG. 5, the heating step 40 includes an immersion step 42, first to third reheating steps 43, 44, and 45. In the immersion step 42, the object to be inspected 10 is immersed in the hot water 55 using the hot water tank 50 shown in FIG. 6. Therefore, first, the structure of the hot water tank 50 will be described in detail while showing FIG. 6.

[0043] Figure 6 shows the hot water tank 50 included in the penetrant flaw detection device according to the present embodiment. The hot water tank 50 includes a lid 54, hot water 55, a heater 56, and a control unit 57. The hot water 55 is at a predetermined temperature. From the perspective of the temperature rise efficiency per unit time of the object to be inspected and the perspective of ensuring the temperature of the surface 11 of the object to be inspected, the predetermined temperature is preferably 90 degrees or more, and more preferably 95 degrees or more. The size of the hot water tank 50 is preferably appropriately designed in proportion to the volume of the object to be inspected 10, and a capacity of 10 times or more the volume of the object to be inspected 10 is preferable. By doing so, the temperature drop of the hot water 55 can be minimized as much as possible. Further, the heater 56 is configured to be controllable by the control unit 57 so as to maintain the hot water 55 at a predetermined temperature. The heater capacity is increased according to the capacity of the hot water tank 50, but it is preferably 10 L / kW or more. If it is 10 L / kW or more, the device startup time can be shortened, which is preferable. The control unit can use appropriately known means such as sensors and temperature controllers.

[0044] Also, as shown in FIG. 6, the hot water tank 50 included in the penetrant flaw detection device according to the present embodiment further includes a wall portion 62 and a sealing material 61. The wall portion 62 is preferably made of a known material with a heat insulation effect such as a heat insulating material. Further, the sealing material 61 is configured to be able to seal the space between the lid 54 and the hot water tank body in order to seal the lid 54. It is preferable to use an O-ring for the sealing material 61. The fixing method of the O-ring may be performed by known means such as a groove. As the material of the sealing material 61, known materials such as those using rubber can be used, but as a more preferable form, a high-performance fluororubber called Aflas is used. Aflas is a fluororubber manufactured by AGC Chemicals Company. It has excellent chemical resistance against strong alkalis and amines that cannot be handled by general fluororubbers, heat resistance and steam resistance that can be used even in high-temperature environments such as steam, and low odor retention, making it suitable for use as the sealing material 61.

[0045] Next, with reference to FIGS. 5 and 7, the dipping process 42 will be described in detail. In the dipping process 42, as shown in FIG. 7(X), first, the object to be inspected 10 is gripped by the handling device 53 and conveyed directly above the hot water tank 50. When it is conveyed, the lid 54 provided on the hot water tank 50 is in an open state as shown in FIG. 7(X). Then, as shown in FIG. 7(Y), the handling device 53 and the object to be inspected 10 enter the inside of the hot water tank 50 with the lid 54 open, and the object to be inspected 10 is immersed in the hot water 55. At this time, since the temperature of the hot water 55 drops, it is appropriately adjusted by the heater 56 and the control unit 57 that controls the heater 56 and manages the temperature of the hot water 55 so that the temperature becomes constant. For example, when the heater 56 is put into operation before the object to be inspected 10 is immersed in the hot water 55 and heating is started by immersing the object to be inspected 10 in the hot water 55, the adjustment may be made so that the temperature drop is reduced. The time for immersing the object to be inspected 10 in the hot water 55 is preferably within 30 seconds. For example, if the object to be inspected 10 is an aluminum piece with a length of 75 millimeters, a width of 50 millimeters, and a thickness of 8 millimeters, it will reach about 80 degrees in 10 seconds. The transition of this temperature change is shown in Table 1.

[0046]

Table 1

[0047] Table 1 shows the temperature change on the surface of the aluminum piece, which is the object to be inspected, when an aluminum piece with a length of 75 millimeters, a width of 50 millimeters, and a thickness of 8 millimeters is placed in hot water at 95 degrees. According to Table 1, the surface temperature reaches 80 degrees in about 10 seconds, but the subsequent temperature rise becomes gradually gentle. Therefore, when the size of the object to be inspected 10 is of this magnitude, the immersion time of the object to be inspected 10 in the hot water 55 can be within 15 seconds to improve the efficiency of temperature rise, and the overall time required for temperature rise can be shortened, which is preferable.

[0048] In addition, the hot water tank 50 provided in the penetrant flaw detector according to the present embodiment includes a hot water injection unit (not shown). The hot water injection unit may be composed of a hot water recovery unit and a hot water injection nozzle that enables the hot water 55 inside the hot water tank 50 to convect. In the immersion step 42, it is preferable to arrange the hot water injection unit so as to inject hot water toward the recess of the inspection object 10 immersed in the hot water 55. When there are recesses in the inspection object 10, bubbles tend to accumulate, and if bubbles accumulate, the surface 11 may not be uniformly heated. The presence of the hot water injection unit can remove bubbles and uniformly heat the surface 11, and the convection of the hot water 55 can more effectively heat the entire inspection object 10, which is preferable.

[0049] Next, the first to third reheating steps 43, 44, and 45 performed after the immersion step 42 shown in FIG. 5 will be described in detail. FIG. 5 shows that after the immersion step 42, the first reheating step 43 may be performed, the second reheating step 44 may be performed, or the third reheating step 45 may be performed. First, the first reheating step 43 will be described in detail. The first reheating step 43 first includes a step of withdrawing the inspection object 10 from the state of being immersed in the hot water 55 in the immersion step 42. At that time, immediately after at least a part of the inspection object 10 is withdrawn from the hot water 55, the inspection object is heated with superheated steam 59. The step of heating with superheated steam 59 may be performed even after the entire inspection object 10 is withdrawn from the hot water 55 or while a part of the inspection object 10 is being withdrawn from the hot water 55. Performing the step of heating with superheated steam 59 while the inspection object 10 is being withdrawn from the hot water 55 will shorten the time and be more preferable.

[0050] Although FIG. 8 shows a different embodiment, in the penetrant flaw detection apparatus of the present invention, the steam injection unit 51 may be arranged like the steam injection unit 51 shown in FIG. 8. The steam injection unit 51 may be injected at equal intervals. For example, if it is injected from four directions, it may be more preferable to evenly heat the surface 11 of the object to be inspected 10. Further, when a plurality of steam injection units 51 are installed, it is preferable from the viewpoint of making the temperature of the surface 11 uniform that the nozzles of the steam injection units 51 are all installed at an equal distance from the object to be inspected 10. Further, if the steam injection unit 51 is angled 10 to 20 degrees downward from the horizontal direction, the hot water adhering to the surface 11 can be recovered into the hot water tank 50, and the scattering of moisture around can be reduced, which is preferable. The arrangement of this steam injection unit 51 is the same when the second reheating step 44 and the third reheating step 45 are respectively carried out.

[0051] In carrying out the magnetic particle flaw detection method of the present invention, a pretreatment step may be carried out before the heating step 40. In the pretreatment step, when there is oil stain or the like on the surface of the object to be inspected, a pretreatment step of cleaning the surface using an organic solvent or the like is carried out. Regarding the stains such as oil that could not be completely removed in this pretreatment step, the step of heating with superheated steam 59 can also be preferably used to clean the oil stain on the surface of the object to be inspected 10 in order to remove the stains such as oil remaining in the pretreatment before flaw detection. This is also preferable in that the penetrant 21 can be applied to the clean surface 11 during the penetration step 31 due to this cleaning effect.

[0052] Next, the case where the second reheating step 44 is performed after the immersion step 42 will be described in detail. The second reheating step 44 is a step of heating the object to be inspected 10 with high-temperature hot air 60 at 100 degrees Celsius or higher immediately after at least a part of the object to be inspected 10 is withdrawn from the hot water 55 in the hot water tank 50. Immediately after at least a part of the object to be inspected 10 is withdrawn from the hot water 55 means that it may be even after the entire object to be inspected 10 is withdrawn from the hot water 55 or even while a part of the object to be inspected 10 is being withdrawn from the hot water 55. After warming the surface 11 of the object to be inspected 10 to around 70 to 85 degrees by the hot water 55 and then heating it with the high-temperature hot air 60, the temperature rise time of the surface 11 can be shortened, and compared with the case of heating with superheated steam, more moisture on the surface 11 can be removed, so it is more suitable. The high-temperature hot air 60 is jetted toward the surface 11 of the object to be inspected 10 by the hot air jetting unit 58. The hot air jetting unit 58 may be composed of known means such as a hot air nozzle, and this hot air nozzle may be connected to a hot air generator (not shown).

[0053] Next, the case where the third reheating step 45 is performed after the immersion step 42 will be described in detail with reference to FIG. 8. The third reheating step 45 is a step of heating the object to be inspected with superheated steam 59 for 1 to 4 seconds immediately after at least a part of the object to be inspected 10 is withdrawn from the hot water in the hot water tank, and then heating the object to be inspected with high-temperature hot air 60 at 100 degrees Celsius or higher for 1 to 5 seconds immediately after that. Immediately after at least a part of the object to be inspected 10 is withdrawn from the hot water 55 means that it may be even after the entire object to be inspected 10 is withdrawn from the hot water 55 or even while a part of the object to be inspected 10 is being withdrawn from the hot water 55. As shown in FIG. 8, immediately after the object to be inspected 10 is withdrawn from the hot water 55, the superheated steam 59 is jetted by the steam jetting unit 51 toward the surface 11 of the object to be inspected 10 slightly downward. The steam jetting unit 51 may be one or plural, but it is preferable to arrange four in the circumferential direction so as to uniformly heat the surface 11 of the object to be inspected 10.

[0054] In the third reheating step 45, after warming the surface 11 of the object under inspection 10 to around 70 to 85 degrees by the hot water 55, immediately after heating the surface 11 for 1 to 4 seconds by the superheated steam 59 injected from the steam injection unit 51, the portion of the surface 11 superheated by the superheated steam 59 is heated for 1 to 5 seconds with the hot air 60 at a high temperature of 100 degrees Celsius or more for the object under inspection. As shown in FIG. 8, the surface 11 may be heated by the hot air 60 simultaneously while being superheated by the superheated steam 59, as long as the portion heated by the superheated steam 59 is configured to be heated by the hot air 60 immediately thereafter. Of course, it does not have to be simultaneous, and it may be heated by the hot air 60 after being heated by the superheated steam 59. The specific heat of water is about 4.2 J / g·°C, and the specific heat of air is about 1 kJ / kg·°C, with a difference of more than four times. Therefore, to obtain the same temperature rise effect as the superheated steam 59 only with the hot air 60, the air temperature has to be raised. However, if the air temperature is raised too much, due to the risk of fire, the temperature cannot be increased arbitrarily and the time cannot be extended. Also, although the heating time can be shortened by increasing the wind speed of the hot air 60, there is also a limit to this. Therefore, it is also suitable to attempt to raise the temperature of the surface 11 only with the hot water 55 and the hot air 60. However, it is a more preferable form to heat the surface 11 with the superheated steam 59 after immersing it in the hot water 55 and then heat the surface 11 with the hot air 60 to remove the moisture as well.

[0055] The penetrant flaw detection device according to this embodiment when performing the first to third reheating steps 43, 44, 45 will be described in more detail. The penetrant flaw detection device according to this embodiment may further include a thermometer to manage the temperature of the surface 11 of the object under inspection 10. It is preferable to use a non-contact thermometer, for example, a radiation thermometer. Also, the steam injection unit 51 may enter the inside of the hot water tank 50 and inject the superheated steam 59 in the first reheating step 43 and the third reheating step 45. By doing so, the scattering of moisture to the surroundings is reduced, which is more preferable from the perspective of environmental consideration.

[0056] Next, in the penetrant testing method and penetrant testing device of the present invention, the heating means in the case of heating the surface 11 with superheated steam 59 will be described in detail. In the case of superheated steam 59, as an example of this embodiment, the penetrant testing device includes one or more steam injection units 51. The steam injection unit 51 is composed of an injection nozzle, a hose, a steam supply source, etc., but as long as it can inject steam onto the surface 11, it may be by appropriately known means. The superheated steam 59 is injected toward the surface 11 by the steam injection unit 51. At this time, the superheated steam 59 preferably has a vapor pressure of 0.03 megapascals or more. Thereby, the air on the surface 11 becomes heated steam. And steam also penetrates into the defect interior 14 and fills the defect interior 14. Also, by heating not only the surface 11 but also the vicinity of the surface 16, the air in the defect interior 14 is prevented from cooling immediately. By heating in this way, in the penetration step 31 shown in FIG. 3, when the state shown in FIG. 4(X) is reached, the air remaining in the defect interior 14 is heated. After the penetration step 31, this heated air is cooled by the cooling effect of cooling from the inner part of the test object 10, cooling by the penetrant 21, and cooling by the cooling step 41 during the penetration time, and the steam condenses. When the steam in the defect interior 14 condenses, a differential pressure is generated between the air in the defect interior 14 and the atmospheric pressure, and the penetrant 21 is drawn into the defect interior 14. In this way, the penetration time for the penetrant 21 to penetrate into the defect interior 14 is shortened.

[0057] Next, in the penetrant flaw detection method and apparatus of the present invention, the heating means in the case of heating the surface 11 by the high-temperature hot air 60 will be described in detail. The high-temperature hot air 60 is jetted toward the surface 11 of the object to be inspected 10 by the hot air jetting section 58. The hot air jetting section 58 may be composed of known means such as a hot air nozzle, and this hot air nozzle is directly connected to a hot air generator (not shown) or connected through a pipe. The high-temperature hot air 60 is preferably 100 degrees Celsius or higher, but when it is 150 to 250 degrees Celsius and the wind speed is 10 to 20 m / s, moisture can be dried quickly, which is more preferable. By heating in this way with the high-temperature hot air 60, in the penetration step 31 shown in FIG. 3, when it reaches the state shown in FIG. 4(X), the air remaining inside the defect 14 is heated. After the penetration step 31, this heated air is cooled by the cooling effect of cooling from the inner part of the object to be inspected 10, cooling by the penetrant 21, and cooling in the cooling step 41 during the penetration time, and a differential pressure is generated between the air inside the defect 14 and the atmospheric pressure, and the penetrant 21 is drawn into the defect 14. In this way, the penetration time for the penetrant 21 to penetrate into the defect 14 is shortened.

[0058] In the case of an embodiment in which steam is used for the heating means of the penetrant flaw detection apparatus and the penetrant flaw detection method of the present invention, for example, with a gauge pressure of 0 megapascals and a specific volume of saturated water at a saturation temperature of 100 degrees Celsius of 0.00104 m^3 / kg, the saturated steam is 1.673 m^3 / kg, and the volume is about 1700 times. Therefore, a large volume change occurs, and the generation of differential pressure also becomes correspondingly large, making it possible to significantly shorten the penetration time.

[0059] Next, the relationship between performing the heating step 40 and the acceleration of the penetration time will be described. When heating the surface 11 at an absolute temperature of 50 degrees Celsius by the heating means in the heating step 40, theoretically, in the heating step 40, for example, when the air at 25 degrees Celsius is raised by 50 degrees Celsius, the volume expands and increases by 17 percent. In this state, the penetration step 31 is performed and the penetrant 21 is applied to the surface 11. Then, in addition to the force trying to enter the interior 14 of the defect of the penetrant 21 itself, the volume of the air in the defect interior 14, which had expanded by 17 percent, returns to its original state as it approaches room temperature, and the volume decreases by approximately 17 percent. As a result, a large amount of the penetrant 21 can be instantaneously drawn into the defect interior 14.

[0060] Next, the penetrant flaw detection device of the present invention will be further described. The penetrant flaw detection device of the present invention may include heating means for performing the heating step 40, penetration means for performing the penetration step 31, cooling means for performing the cooling step 41, cleaning means for performing the cleaning step 32, developing means for performing the developing step 33, and observing means for performing the observing step 34, respectively. As the penetration means, known means such as means for applying the penetrant 21 to the object to be inspected 10 by a spraying device may be used. In the cooling means, known devices such as blowing cold air or immersing in cold water may be used. In the cleaning means, a coating device or the like for applying a cleaning liquid to the object to be inspected 10 may be used. As the developing means, a device or the like for applying a developer to the object to be inspected 10 may be used. As the observing means, in addition to visual inspection, known means such as an imaging device for moving images or still images may be used for each. Further, the penetrant flaw detection device of the present invention may be appropriately designed to be able to implement the penetrant flaw detection method of the present invention.

[0061] The present disclosure can be suitably used for the purpose of inspecting defects such as billets made of non-magnetic materials in particular as the object to be inspected 10. However, it is not limited to this, and it can be widely used in the inspection of products that require flaw detection.

Description of Reference Numerals

[0062] 10, Object to be inspected 11, Surface 12, Defect 13, Defective opening 14, Inside the defect 16, Near-surface part 21, Penetrant 31, Penetration process 32, Cleaning process 33, Development process 34, Observation process 40, Heating process 41, Cooling process 42, Immersion process 43, First reheating process 44 Second reheating process 45 Third reheating process 50, Hot water tank 51, Steam injection part 53, Handling device 54 Lid 55 Hot water 56 Heater 57 Control unit 58 Hot air injection part 59 Superheated steam 60 High-temperature hot air 61 Sealing material 62 Wall part

Claims

1. In a penetrant inspection method sequentially comprising a penetration step of applying a penetrant to an object to be inspected, a cleaning step of removing the penetrant on the surface of the object to be inspected, and an observation step of observing an indication pattern, the penetrant inspection method further comprises a heating step before the penetration step, the heating step is a step of sequentially performing an immersion step and a first reheating step, the immersion step is a step of immersing the object to be inspected in hot water at 90° C. or higher in a hot water tank for 30 seconds or less, the first reheating step is a step of heating the surface of the object to be inspected with superheated steam immediately after at least a part of the object to be inspected is withdrawn from the hot water in the hot water tank, characterized in that it is a penetrant inspection method.

2. In a penetrant inspection method sequentially comprising a penetration step of applying a penetrant to an object to be inspected, a cleaning step of removing the penetrant on the surface of the object to be inspected, and an observation step of observing an indication pattern, the penetrant inspection method further comprises a heating step before the penetration step, the heating step is a step of sequentially performing an immersion step and a second reheating step, the immersion step is a step of immersing the object to be inspected in hot water at 90° C. or higher in a hot water tank for 30 seconds or less, the second reheating step is a step of heating the surface of the object to be inspected with hot air at 100° C. or higher immediately after at least a part of the object to be inspected is withdrawn from the hot water in the hot water tank, characterized in that it is a penetrant inspection method.

3. In a penetrant inspection method sequentially comprising a penetration step of applying a penetrant to an object to be inspected, a cleaning step of removing the penetrant on the surface of the object to be inspected, and an observation step of observing an indication pattern, the penetrant inspection method further comprises a heating step before the penetration step, the heating step is a step of sequentially performing an immersion step and a third reheating step, the immersion step is a step of immersing the object to be inspected in hot water at 90° C. or higher in a hot water tank for 30 seconds or less, the third reheating step is a step of heating the surface of the object to be inspected with superheated steam for 1 to 4 seconds immediately after at least a part of the object to be inspected is withdrawn from the hot water in the hot water tank, and immediately thereafter heating the portion of the surface of the object to be inspected heated with superheated steam with hot air at 100° C. or higher for 1 to 5 seconds, characterized in that it is a penetrant inspection method.

4. A penetrant inspection apparatus comprising a heating means, a penetration means, a cleaning means, and an observation means, the heating means is characterized by comprising a hot water tank and a steam injection part capable of injecting superheated steam, a penetrant inspection apparatus. **Claim 5** A penetrant flaw detection device comprising a heating means, a penetration means, a cleaning means, and an observation means, wherein the heating means includes a hot water tank and a hot air injection unit capable of injecting high-temperature hot air, characterized in that it is a penetrant flaw detection device. **Claim 6** The penetrant flaw detection device according to claim 4 or 5, characterized in that the hot water tank includes a hot water injection unit capable of allowing hot water to convect inside. **Claim 7** The penetrant flaw detection device according to claim 4 or 5, characterized in that the hot water tank is provided with a lid, and the lid is provided with a steam-resistant sealing material.

Images