JP3847185B2 - Magnetic powder flaw detection sheet - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention is for magnetic particle flaw detection in which a magnetic powder made of magnetic particles and a gas or a fluid material having fluidity are enclosed in a space between a transparent surface material and a back material facing the transparent surface material. Regarding the sheet, in particular, when performing magnetic particle flaw detection, the magnetic powder used when patterning the magnetic flux leaked from the object to be inspected by the enclosed magnetic powder by bringing it into close contact with the surface of the object to be inspected that has been magnetized. The present invention relates to a flaw detection sheet.
[0002]
[Prior art]
As the magnetic particle flaw detection sheet configured as described above, a sheet having the following configuration has been proposed. In other words, a surface material made of a flexible and transparent resin film and a back material made of a flexible resin film are overlaid, and the periphery of each is molded into a sheet shape. A magnetic sheet made of magnetic particles and a fluid material having fluidity are enclosed in a space between the two so as to form a flexible sheet as a whole. The magnetic flaw detection sheet of this configuration is used in a form that is in close contact with the inspection surface of the object to be inspected to which the magnetism generated by the magnetism generating part or the like is applied. When there is a defect, it is possible to perform flaw detection visually or using image information using a camera or the like by utilizing the property that magnetic particles are aligned along the magnetic flux leaked from the site.
[0003]
As a conventional flaw detection method different from the flaw detection method using this magnetic particle flaw detection sheet, magnetic powder mixed with fluid or dry magnetic powder is directly sprayed on the surface of the object to be inspected, and magnetism is applied to the object to be inspected. There is an open type flaw detection method for observing the state. However, in this open type flaw detection method, when the magnetic particles are sprayed on the object to be inspected, the fluid environment containing the magnetic particles or the dried magnetic particles may fall on the operator, so that the working environment is easily deteriorated. This open type flaw detection method not only requires the collection of magnetic particles, but when flaw detection is performed on the surface to be inspected, the pattern on the painted surface is regarded as a pseudo pattern (pseudo pattern). In addition, there is a disadvantage that the magnetic powder remains in close contact with the painted surface, and the above-described magnetic powder flaw detection sheet was considered.
[0004]
In addition, as a technique similar to the magnetic particle flaw detection sheet, there is a technique assumed to be used in water, such as that disclosed in JP-A-56-40752. This technology fills the inside of an inspection cassette with a bottom surface made of a flexible material with a suspension of inspection liquid and magnetic powder for inspection, and magnetically applies to the object to be inspected in a state where the bottom surface is in contact with the object to be inspected. However, when there are relatively large irregularities on the surface of the object to be inspected, there is a surface that is difficult to adhere, and the inspection cassette itself is relatively large in size. Therefore, the necessity of the magnetic particle flaw detection sheet of the present invention is increasing.
[0005]
[Problems to be solved by the invention]
However, the magnetic particle flaw detection sheet proposed as described above is in close contact with the surface of the object to be inspected, and magnetic flux leaking from the defective portion of the object to be inspected is patterned with magnetic powder. It is necessary to make the thickness of the sheet as thin as possible so that it can be easily observed from the side. However, if the thickness of the magnetic particle flaw detection sheet is made too thin, the distance between the front surface material and the back surface material becomes almost equal to the particle size of the magnetic powder, and the magnetic powder cannot move freely even when magnetism acts. However, the detection sensitivity was lowered.
[0006]
An object of the present invention is to rationally constitute a magnetic particle flaw detection sheet that can perform flaw detection with high sensitivity without impairing good surfaces.
[0007]
[Means for Solving the Problems]
The features, functions and effects of the magnetic particle flaw detection sheet according to claim 1 of the present invention are as follows.
〔Characteristic〕
In the magnetic particle flaw detection sheet formed by enclosing magnetic powder composed of magnetic particles in a space between a transparent surface material and a back material facing the transparent surface material, and a fluid substance having gas or fluidity, It is in the point provided with the space | interval formation body comprised with the textile fabric which has the mesh open | released in the up-down direction which forms the space | interval which permits the motion of the said magnetic powder between a surface material and a back surface material.
[0008]
[Action / Effect]
According to the above characteristics, when a pressure is applied or when the entire body is curved by providing a gap forming body composed of a woven fabric having a mesh that opens in the vertical direction between the front surface material and the back surface material. In addition, it is possible to secure an interval allowing the movement of the magnetic powder between the surface material and the back material. For example, the gap between the surface material and the back material is set to a value slightly larger than the particle size of the magnetic powder to ensure the state of the magnetic powder. It is also possible to observe. In other words, even if the sheet thickness of the magnetic particle flaw detection sheet is reduced, free movement of the magnetic powder is not hindered, and even if the surface to be inspected has irregularities, the sheet is deformed with high precision along the irregularities and inspected. Can do. As a result, a magnetic particle flaw detection sheet that enables flaw detection with high accuracy was rationally constructed. In particular, according to the present invention, since the magnetic powder is sealed and used, there is no inconvenience that the magnetic powder is scattered at the time of operation, and it is possible to work in a good environment, and it is possible to eliminate erroneous detection due to the pseudo pattern, It can also be used for flaw detection.
[0010]
Further , since the gap forming means is composed of a woven fabric that opens in the vertical direction, the movement of the magnetic powder is allowed in a portion where the fibers forming the woven fabric do not exist, and the woven fabric is accommodated on substantially the entire surface of the sheet. By using the size, the entire surface of the sheet can be maintained at a uniform interval. Specifically, even when flaw detection is performed using a woven fabric having a mesh size of about 100 μm, the magnetic powder wraps around the fiber portion forming the mesh, and a pattern (pattern) that can be sufficiently confirmed against magnetism is formed. I was able to confirm that it was produced. Specifically, it was made possible to detect the test piece of JISA1-15 / 100 (straight line) clearly. As a result, high-precision flaw detection was realized simply by using a relatively easily available fabric.
[0011]
The features, functions and effects of the magnetic particle flaw detection sheet according to claim 2 of the present invention are as follows.
〔Characteristic〕
2. The magnetic particle testing sheet according to claim 1, wherein the woven fabric having the mesh is formed with an opening having a size of 0.1 to 10 mm on one side .
[0012]
[Action / Effect]
According to the above characteristics, since the woven fabric having a mesh forms an opening having a size of 0.1 to 10 mm on one side, it can be confirmed that a pattern (pattern) that can be sufficiently confirmed against magnetism can be created. It was. As a result, high-accuracy flaw detection was realized.
[0013]
The features, functions and effects of the magnetic particle flaw detection sheet according to claim 3 of the present invention are as follows.
〔Characteristic〕
3. The magnetic particle testing sheet according to claim 1, wherein the magnetic powder has a particle size of 0.1 to 100 [mu] m .
[0014]
[Action / Effect]
According to the above characteristics, since the magnetic powder has a particle size of 0.1 to 100 μm, the magnetic powder can easily move, and the pattern created by the magnetic powder when magnetism acts can be observed with high accuracy from the surface material side. It became a thing.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[First embodiment]
As shown in FIGS. 1 and 2, the magnetic particle flaw detection sheet S brought into contact with the surface of the inspection object 1, the pressing means P for pressing the magnetic particle inspection sheet S against the inspection object 1, and the inspection object 1 A magnetic particle flaw detector is provided with a magnetism generator M that acts on magnetism. This magnetic particle flaw detector is an example of a configuration for performing flaw detection using the magnetic particle flaw detection sheet S of the present invention. In this magnetic particle flaw detector, a magnetic material typified by iron is the object 1 to be inspected, specifically an iron plate. It is possible to inspect the excess portion 1A (see FIG. 2) of the welded portion of the material and the defect C (scratches such as cracks) of the curved portion of the steel pipe.
[0016]
As shown in FIGS. 3 (a) and 3 (b), the magnetic particle flaw detection sheet S includes an upper surface material 10 made of a flexible and transparent resin film, and a lower surface material 11 made of a flexible resin film. And a flexible sheet-like container in which a gap d is formed by sandwiching a gap forming body D made of a woven fabric having a mesh that opens in the vertical direction between the surface material 10 and the back surface material 11. In this container, a magnetic material 13 having a magnetic material and having a particle size sufficiently smaller than the above interval and a fluid substance 14 having gas or fluidity are enclosed. In addition, the container for the magnetic particle flaw detection sheet S has a sealed structure by joining the outer peripheral portion of the front surface material 10 and the back surface material 11 using a thermal welding technique or an adhesive. Those coated with a fluorescent material may be used.
[0017]
Specifically, the film thickness of the surface material 10 and the back material 11 is about 0.02 to 0.5 mm, and it is essential that the surface material 10 of the container is transparent, Some colored material may be used, and the back material 11 does not need to be transparent, and a colored resin can also be used. Polyethylene, polyvinyl, or PET (polyethylene terephthalate) resin can be used as the surface material 10 and the back material 11, and soft magnetic austenitic stainless steel foil can be used as the back material 11 instead of the resin film. Is also possible. The gap forming body D is a mesh (opening) having a size of about 0.1 to 10 mm on one side using synthetic fibers such as nylon fibers having a diameter of the strand 16 of about 0.01 to 1 mm for warp and weft. And a woven fabric having a thickness of about 0.01 to 3 mm is cut into approximately the same size as the internal space of the container.
[0018]
As the material of the magnetic powder 13, a magnetic material having a particle size of 0.1 to 100 μm is used. As this magnetic material, not only iron and nickel but also magnetite and gamma-hectite can be used, and the pattern created by the magnetic powder 13 by the magnetic flux leaking from the inspection object 1 can be easily recognized by the fluorescence of the fluorescent material. ing. Moreover, as this magnetic powder 13, a non-spherical thing can be used, and the particle size in the case of a non-spherical thing has pointed out the size of the site | part used as the maximum dimension. The fluid substance 14 is a liquid such as water or kerosene.
[0019]
As shown in FIG. 2, the pressing means P is a polyvinyl chloride for a bag 20 </ b> A in which a polyethylene film or a polyvinyl film having a film thickness of about 0.1 to 0.5 mm is molded into a bag shape as a flexible and transparent resin film. A gel-like (slime-like) material 20B (which may be water) filled with alcohol and borax or a gel-like material (for example, a net-like material obtained by copolymerizing polyethylene and styrene is gelled with oil. A pressure-bonding member 20 having a property that can be flexibly deformed, and a pressure-bonding plate 21 formed by flatly molding a transparent glass plate or a resin plate made of a material such as an acrylic resin that easily obtains good transparency, It consists of
[0020]
The magnetism generator M supplies an electric magnet to a coil 31 made of a good conductor such as a copper alloy around an iron core 30 having a pair of magnetic poles 30P and 30P that are in contact with the object 1 to be inspected, and supplies power to the coil 31 of the electromagnet. And a power source 32.
[0021]
With this magnetic particle flaw detector, as the object 1 to be inspected, when performing a flaw detection on a welded portion of a steel plate constituting a gas holder for storing gas, a tank for storing oil or the like, or a steel plate constituting a bridge or the like The procedure is as follows. In the inspection object 1 shown in FIG. 2, it is assumed that a defect C exists in the area of the surplus 1A of the welded portion. When performing inspection of the inspection object 1, as shown in FIG. Then, the magnetic particle flaw detection sheet S is placed on the site where flaw detection is to be performed, and the pressure-bonding member 20 and the pressure-bonding plate 21 are stacked on the upper surface. In the state of being placed in this way, even if the surplus 1A is present in the welded portion as shown in the figure, the entire bottom surface of the magnetic particle flaw detection sheet S is deformed into a shape along the surplus 1A portion. Adhering closely to the upper surface of the object 1 to be inspected, the lower surface of the crimping member 20 is deformed into a shape along the shape of the upper surface of the magnetic particle flaw detection sheet S to apply a uniform pressure. As a result, the upper surface of the crimping member 20 is crimped. Flatten along the lower surface of the plate 21.
[0022]
After setting in this way, the posture of the electromagnet is determined in a state where the magnetic poles 30P, 30P are arranged at a position straddling the magnetic particle flaw detection sheet S, the magnetic poles 30P, 30P are brought into contact with the object to be inspected, and By supplying electric power from the power source 32 and causing the magnetic field from the electromagnet to act on the inspection object 1, the magnetic flux from the iron core 30 is guided to the inside of the inspection object 1, and between the iron core 30 and the inspection object 1. If a magnetic circuit is formed in the magnetic circuit and a defect C exists in the magnetic circuit, the amount of magnetic flux leakage at the defect C increases and acts on the magnetic powder 13 of the magnetic particle flaw detection sheet S. As a result, the leaked magnetic flux By creating a pattern in which magnetic particles 13 form a line along the direction of, and comparing this pattern with a pattern of a portion with a small amount of magnetic flux leakage, the presence or absence of a defect C is photographed visually or with a camera. The ones that can be grasped iconic in the case was.
[0023]
As described above, in the first embodiment, the surface material 10 is formed by sandwiching the surface material 10 and the back material 11 with a woven fabric having a size substantially equal to the entire surface of the sheet as the gap forming member D. Since the space between the back surface material 11 and the back surface material 11 is secured, the magnetic powder 13 can be moved easily by maintaining the entire surface of the sheet at a uniform distance while making the sheet relatively thin. The pattern produced by the magnetic powder 13 when acted on can be observed with high accuracy from the surface material 10 side of the magnetic particle flaw detection sheet S. In particular, the magnetic particle flaw detection sheet S formed into a flexible sheet, the pressure-bonding member 20 configured to be flexible and deformable but capable of transmitting pressure, and the pressure-bonding plate 21 that hardly deforms are combined to produce a magnetic particle flaw detection. The inspection sheet S is brought into close contact with the surface of the object 1 to be inspected without causing a gap, thereby improving the inspection accuracy.
[0024]
[Second Embodiment]
In the second embodiment, only the magnetic particle flaw detection sheet S is different from the first embodiment, and the magnetic particle flaw detection apparatus used for flaw detection is assumed to have the same configuration as that of the first embodiment (see above). Those having the same functions as those of the first embodiment are given the same numbers and symbols as those of the first embodiment).
[0025]
As shown in FIGS. 4 (a) and 4 (b), the magnetic particle flaw detection sheet S has a plurality of protrusions with respect to at least one of the opposing surfaces of the surface material 10 and the back surface material 11 (which may be either surface). By forming the portion as a gap forming body D, a gap d is formed between the front surface material 10 and the back surface material 11, and the particle diameter is sufficiently smaller than the gap by a magnetic material with respect to the space of the gap d. The particulate magnetic powder 13 and the fluid substance 14 having gas or fluidity are enclosed. In addition, the container for the magnetic particle flaw detection sheet S has a sealed structure by joining the outer peripheral portion of the front surface material 10 and the back surface material 11 using a thermal welding technique or an adhesive. Fluorescent material is coated.
[0026]
The protruding amount of the space forming body D (which coincides with the space d) is set to 20 to 30 μm, and the space between the protruding portions is set to about 100 μm. Forming. In the figure, the protruding portion is constituted by a protruding material 17 that is bonded and fixed to one of the front surface material 10 and the back surface material 11. As the magnetic powder, one having a particle size sufficiently smaller than 20 μm coated with a fluorescent substance so that it can move at the interval between the front surface material and the back surface material is used, and for example, about 0.1 to 10 μm can be used.
[0027]
In the case where the gap forming body D is formed in a projecting manner in this way, the film is formed in at least one of the manufacturing steps of the front surface material 10 and the back surface material 11 instead of forming the projecting material 17 by bonding and fixing as described above. Use the one in which the projecting portion is integrally formed on the surface, or use the one in which the gap forming body D is formed in a projecting state by processing such as grinding at least one film surface of the surface material 10 and the back material 11 It is also possible to carry out.
[0028]
As described above, in the second embodiment, a plurality of interval forming bodies D are formed on the magnetic particle flaw detection sheet S as the interval forming bodies D so as to protrude from at least one of the surface material 10 and the back surface material 11. By securing a predetermined distance between the material 11 and the material 11, the sheet is made relatively thin, but the entire surface of the sheet is maintained at a uniform distance, and the magnetic powder 13 is easily moved, so that magnetism acts. In this case, the pattern produced by the magnetic powder can be observed with high accuracy from the surface material side.
[0029]
[Third Embodiment]
In the third embodiment, only the magnetic particle flaw detection sheet S is different from the first embodiment, and the magnetic particle flaw detection apparatus used for flaw detection is assumed to have the same configuration as that of the first embodiment (see above). Those having the same functions as those of the first embodiment are given the same numbers and symbols as those of the first embodiment).
[0030]
As shown in FIGS. 5 (a) and 5 (b), the magnetic particle flaw detection sheet S includes an upper surface material 10 made of a flexible and transparent resin film, and a lower surface material 11 made of a flexible resin film. A flexible sheet-shaped container using a magnetic material, and a magnetic particle 13 having a predetermined particle size with a magnetic material, and a spherical interval having a particle diameter sufficiently larger than the particle diameter of the magnetic powder By enclosing the formed particles 18 (interval forming body D) and the fluid substance 14 having gas or fluidity, the interval d (the diameter of the interspace forming particles 18 matches the space between the surface agent 10 and the back surface material 11). ). In addition, the container for the magnetic particle flaw detection sheet S has a sealed structure by joining the outer peripheral portion of the front surface material 10 and the back surface material 11 using a thermal welding technique or an adhesive. Fluorescent material is coated.
[0031]
The materials and dimensions of the surface material 10, the back material 11, and the magnetic powder 13 are as described in the first embodiment. The material of the space-forming particles 18 as the space-forming body D is not broken when pressure is applied, and is preferably a non-magnetic material, for example, resin, glass, brass, or a uniform particle size. Sand can also be used. In particular, when the fluid substance 14 enclosed in the sheet is a liquid, by using a material in which the specific gravity of the gap-forming particles 18 is as close as possible to the specific gravity of the liquid, it is possible to eliminate unevenness in the sheet. desirable.
[0032]
Thus, in the third embodiment, since the plurality of spherical interval forming particles 18 are interposed in the sheet as the interval forming body D in the magnetic particle flaw detection sheet S, the sheet is made relatively thin. Without special processing, the magnetic powder 13 can be easily moved while maintaining the entire surface of the sheet at a uniform interval, and the pattern produced by the magnetic powder when magnetism acts can be observed with high accuracy from the surface material side. I'm making things.
[Brief description of the drawings]
FIG. 1 is an overall perspective view showing the arrangement of components of the magnetic flaw detector according to the first embodiment. FIG. 2 is a cross-sectional view showing the arrangement of components of the magnetic flaw detector according to the first embodiment. Sectional view and partially cutaway plan view of a magnetic flaw detection sheet according to one embodiment FIG. 4 is a sectional view and partly cutaway plan view of a magnetic flaw detection sheet according to a second embodiment. FIG. 5 is a third embodiment. Sectional view and partially cutaway plan view of the magnetic flaw detection sheet
DESCRIPTION OF SYMBOLS 10 Surface material 11 Back surface material 13 Magnetic powder 14 Fluid substance 18 Particle | grain D Spacing body

Claims (3)

A magnetic particle flaw detection sheet comprising a magnetic powder composed of magnetic particles and a gas or a fluid material having fluidity in a space between a transparent surface material and a back material facing the transparent surface material. ,
A magnetic particle flaw detection sheet comprising a gap forming body formed of a woven fabric having a mesh opened in the vertical direction, which forms a gap allowing movement of the magnetic powder between the surface material and the back material.   2. The magnetic particle testing sheet according to claim 1, wherein the woven fabric having the mesh forms an opening having a size of 0.1 to 10 mm on a side.   The magnetic powder flaw detection sheet according to claim 1, wherein the magnetic powder has a particle size of 0.1 to 100 μm.

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