Sensor protection structure, sensor mounting method and test piece

Abstract

To provide a sensor protection structure, a sensor mounting method and a test piece, which can prevent deterioration of a sensor mounted on a measurement object.SOLUTION: A protection structure 16 protects a sensor 14. The sensor 14 has a detection part 40 stuck to a surface 12a of a clip 12, and a lead wire 42 connected to the detection part 40. The protection structure 16 includes a metallic foil 22 which is provided so as to cover a connection part of the detection part 40 out of the detection part 40 and the lead wire 42, and a resin layer 26 which is formed so as to cover a boundary part between the outer edge of the metallic foil 22 and the surface 12a. The metallic foil 22 is bonded to the surface 12a by an adhesive layer 24 formed in the outside of the detection part 40 so as to surround the detection part 40.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a protective structure for a sensor, a method for mounting a sensor, and a test specimen. [Background technology]

[0002] In order to evaluate material properties under a specific environment, tests are sometimes performed with sensors attached to a test piece. For example, when a test using a strain gauge is performed in a harsh environment such as a wet hydrogen sulfide environment, it is necessary to protect the strain gauge in order to stabilize the output. Therefore, methods for protecting the strain gauge have been proposed in the past.

[0003] For example, a coating structure for a strain gauge attachment portion is disclosed in Patent Document 1. In the coating structure disclosed in Patent Document 1, the attachment portion of a strain gauge attached to an object to be measured is coated with a metal plating layer by electroless plating.

[0004] Patent Document 1 describes that by covering the attachment point of the strain gauge as described above, it is possible to improve the ability to maintain moisture resistance and electrical insulation at the attachment point of the strain gauge. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 7-35628 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the structure disclosed in Patent Document 1, the metal plating layer is formed by electroless plating, so the strain gauge must be immersed in a high-temperature (80 to 90°C) plating solution when forming the metal plating layer. In this case, the strain gauge also becomes hot, which may cause it to deteriorate.

[0007] The present invention has been made to solve such problems, and aims to provide a sensor protection structure, a sensor mounting method, and a test specimen that can prevent deterioration of a sensor attached to an object to be measured. [Means for solving the problem]

[0008] The present invention relates to the following sensor protection structure, sensor mounting method, and test specimen.

[0009] (1) A protective structure for protecting a sensor having a detection part attached to a surface of an object to be measured and a lead wire connected to the detection part, a first metal foil provided so as to cover the detection portion and at least a connection portion of the lead wire with the detection portion; A first resin layer is formed so as to cover a boundary portion between an outer edge of the first metal foil and the surface of the object to be measured, A protective structure for a sensor, wherein the first metal foil is adhered to the surface of the object to be measured by an adhesive layer formed outside the detection portion so as to surround the detection portion.

[0010] (2) The protective structure for a sensor according to (1) above, wherein a gap is formed between the first metal foil and the surface of the object to be measured.

[0011] (3) a protective tube made of resin through which the lead wire passes; A second metal foil is wound around the lead wire so as to cover a portion of the lead wire at a position away from the detection unit, One end side of the second metal foil in the length direction of the lead wire is covered with the first metal foil, and the other end side of the second metal foil in the length direction of the lead wire is inserted into the protective tube, The protective structure for a sensor described in (1) above, wherein the first resin layer is formed to cover the portion of the second metal foil exposed from the first metal foil and the protective tube, and to block the opening of the protective tube on the detection section side.

[0012] (4) A second resin layer made of a resin different from the first resin layer is further provided, the first resin layer is formed such that a central portion of the first metal foil is exposed from the first resin layer; The protective structure for a sensor according to (1) above, wherein the second resin layer is formed so as to cover the first resin layer and the portion of the first metal foil that is exposed from the first resin layer.

[0013] (5) the sensor is a strain gauge; The protective structure for a sensor according to (1) above, wherein the measurement object is a test piece or a clip attached to the test piece.

[0014] (6) A method for attaching a sensor having a detection unit and a lead wire connected to the detection unit to a measurement object, comprising the steps of: A step of attaching the detection unit to a surface of the measurement object; A method for mounting a sensor comprising the steps of: forming the protective structure described in (1) above.

[0015] (7) A test specimen or a clip attached to the test specimen; a sensor for measuring the test piece or the clip, the sensor having a detection unit attached to a surface of the measurement object and a lead wire connected to the detection unit; A test specimen comprising the protective structure described in (1) above. Effect of the Invention

[0016] According to the present invention, it is possible to prevent deterioration of a sensor attached to a measurement object such as a test piece. [Brief description of the drawings]

[0017] [Figure 1]FIG. 1 is a schematic diagram showing a test specimen according to one embodiment of the present invention. [Diagram 2] FIG. 2 is an enlarged view showing the clip, the sensor and the protective structure. [Diagram 3] FIG. 3 is a schematic cross-sectional view showing a portion AA in FIG. [Figure 4] FIG. 4 is a diagram showing a modified example of the protective structure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A sensor protection structure, a sensor mounting method, and a test specimen according to an embodiment of the present invention will be described below with reference to the drawings.

[0019] (Test specimen configuration) FIG. 1 is a schematic diagram showing a test specimen 100 according to an embodiment of the present invention. As shown in FIG. 1, the test specimen 100 includes a rectangular parallelepiped test piece 10, a clip 12, a sensor 14, and a protective structure 16. The test piece 10 is made of, for example, a steel material. For example, a fatigue test piece is used as the test piece 10. The test specimen 100 is used, for example, in a fatigue test in a wet hydrogen sulfide environment.

[0020] In this embodiment, the test piece 10 is a known CT (Compact Tension) test piece used as a tensile fatigue test piece, and has a notch 10a. The notch 10a is a notch for crack generation formed in such a way that a crack propagates in a propagation direction intersecting the plate thickness direction and the tensile direction by applying a force to the test piece 10 in a tensile direction perpendicular to the plate thickness direction (depth direction of the paper). The notch 10a is formed in the center of the test piece 10 in the tensile direction. As described above, the test piece 10 is a known CT test piece, and therefore a detailed description of the test piece 10 is omitted.

[0021] The clip 12 is attached to the notch 10a. The clip 12 is a strain-generating body having a substantially C-shape. As the clip 12, a known clip used for measuring opening displacement in a fatigue test can be used, and therefore a detailed description thereof will be omitted. In this embodiment, the clip 12 corresponds to the measurement object.

[0022] Fig. 2 is an enlarged view showing clip 12, sensor 14, and protective structure 16. Fig. 3 is a schematic cross-sectional view showing part AA in Fig. 2. Fig. 2 shows clip 12, sensor 14, and protective structure 16 as viewed from the right side of the paper surface of Fig. 1. Figs. 2 and 3 show sensor 14 and protective structure 16 in a simplified manner.

[0023] As shown in Figures 1 to 3, the sensor 14 is provided on the clip 12. As shown in Figures 2 and 3, the sensor 14 has a detection unit 40 affixed to the surface 12a of the clip 12, and a lead wire 42 connected to the detection unit 40. In this embodiment, the sensor 14 is a strain gauge, and the detection unit 40 includes, for example, a base portion and a resistor (metal foil) provided on the base portion.

[0024] The detection unit 40 is adhered to the surface 12a of the clip 12 by an adhesive (not shown). For example, a cyanoacrylate adhesive is used as the adhesive. As shown in FIG. 3, the lead wire 42 includes a conductor 42a electrically connected to the detection unit 40 and an insulating coating 42b that covers the conductor 42a. One end of the conductor 42a (the end on the detection unit 40 side) is exposed from the insulating coating 42b. The other end of the conductor 42a is connected to a measuring device (not shown). In this embodiment, the opening displacement of the notch 10a can be measured by measuring the change in electrical resistance generated in the detection unit 40 with the measuring device.

[0025] 2 and 3, the protective structure 16 includes a metal foil 20 (see FIG. 3), a metal foil 22, an adhesive layer 24, a resin layer 26, and a protective tube 28. A metal material having excellent corrosion resistance is used as the material of the metal foils 20 and 22. In this embodiment, the material of the metal foils 20 and 22 may be, for example, nickel, aluminum, titanium, gold, platinum, or the like.

[0026] 3, the metal foil 20 is provided so as to cover a part of the lead wire 42 at a position away from the detection unit 40. In this embodiment, the metal foil 20 is provided so as to cover one end (the end on the detection unit 40 side) of the insulating coating 42b and a part of the conductor 42a exposed from the one end.

[0027] The metal foil 20 is wound around the lead wire 42 using an adhesive. The metal foil 20 is also adhered to the surface 12a of the clip 12 using an adhesive. For example, a cyanoacrylate adhesive can be used as the adhesive for fixing the metal foil 20 to the clip 12 and the lead wire 42. In this embodiment, the metal foil 20 corresponds to the second metal foil.

[0028] 2 and 3, the metal foil 22 is provided so as to cover the detection unit 40 and the connection portion of the lead wire 42 with the detection unit 40. As shown in Fig. 2, in this embodiment, the metal foil 22 has a substantially rectangular shape. The thickness of the metal foil 22 is preferably, for example, 0.1 mm or less.

[0029] The metal foil 22 is adhered to the surface 12a of the clip 12 by an adhesive layer 24. In Fig. 2, the position where the adhesive layer 24 is formed is hatched to make the position of the adhesive layer 24 easier to understand. In Fig. 3, a part of the adhesive layer 24 is not shown to avoid cluttering the drawing.

[0030] As shown in Fig. 2, the adhesive layer 24 is formed outside the detection unit 40 so as to surround the detection unit 40. In other words, the detection unit 40 is fixed to the clip 12 at a position inside the adhesive layer 24 and away from the adhesive layer 24. As shown in Fig. 3, in this embodiment, a gap 18 is formed between the surface 12a of the clip 12 and the metal foil 22. The detection unit 40 is disposed in the gap 18.

[0031] In this embodiment, a part of the adhesive layer 24 is formed on the metal foil 20. A part of the metal foil 22 (a part covering the metal foil 20) is fixed to the clip 12 via the adhesive layer 24 and the metal foil 20. The metal foil 20 does not have to be provided. In this case, the conductor 42a is fixed to the clip 12 and the metal foil 22 by, for example, the adhesive layer 24. For example, a cyanoacrylate adhesive can be used as the material of the adhesive layer 24. In this embodiment, the metal foil 22 corresponds to the first metal foil.

[0032] 2 and 3, the resin layer 26 is formed so as to cover the boundary between the outer edge of the metal foil 22 and the surface 12a of the clip 12. In this embodiment, a through hole 26a is formed in the center of the resin layer 26. The center of the metal foil 22 is exposed from the resin layer 26 at the through hole 26a. When viewed from the thickness direction of the resin layer 26, the detection unit 40 is positioned inside the through hole 26a.

[0033] A corrosion-resistant resin is used as the material of the resin layer 26. In this embodiment, for example, polytetrafluoroethylene, polyamide, polycarbonate, polystyrene, vinyl chloride, acrylic, polyvinyl alcohol, ABS, polyethylene, polypropylene, polyacetal, etc. can be used as the material of the resin layer 26. The thickness of the resin layer 26 is preferably 5 mm or more. In this embodiment, the resin layer 26 corresponds to the first resin layer.

[0034] The protective tube 28 is made of a fluororesin. Specifically, the protective tube 28 is made of, for example, polytetrafluoroethylene. In this embodiment, the protective tube 28 has a cylindrical shape. As shown in FIG. 3, one end 28a of the protective tube 28 is embedded in the resin layer 26. The lead wire 42 passes through the protective tube 28 and the resin layer 26 and is connected to the detection unit 40.

[0035] In this embodiment, the metal foil 20 is formed so as to extend from the gap 18 between the surface 12a of the clip 12 and the metal foil 22 into the protective tube 28. In this embodiment, the entire portion of the metal foil 20 that is closer to the protective tube 28 than the metal foil 22 in the length direction of the lead wire 42 is covered with the resin layer 26.

[0036] In this embodiment, the protective tube 28 is formed to have a sufficient length so that when a test is performed in a corrosive environment (wet hydrogen sulfide environment), the test piece 10 can be placed in the corrosive environment and the other end 28b of the protective tube 28 can be placed in a non-corrosive environment. This allows the lead wire 42 inside the protective tube 28 to be appropriately protected from the corrosive environment.

[0037] (How to install strain gauges) An example of a method for attaching the sensor 14 to the above-mentioned test piece 100 will now be briefly described. In the attachment method according to this embodiment, first, the detection unit 40 is attached to the surface 12a of the clip 12 using an adhesive. Next, the metal foil 20 is wrapped around and attached to the lead wire 42. Next, a portion of the metal foil 20 is attached to the surface 12a of the clip 12. If the metal foil 20 is not provided, the lead wire 42 is directly attached to the surface 12a of the clip 12.

[0038] Next, an adhesive is applied onto the surface 12a of the clip 12 to form an adhesive layer 24. Next, the metal foil 22 is adhered to the surface 12a of the clip 12 by the adhesive layer 24. Next, a resin layer 26 is formed. At this time, the protective tube 28 is fixed to the resin layer 26 so that the lead wire 42 passes through the protective tube 28. This completes the installation of the sensor 14 on the test piece 100.

[0039] The procedure for forming the resin layer 26 is not particularly limited, but for example, the resin layer 26 can be formed as follows. First, a resin material is applied so as to cover the outer edge of the metal foil 22. Next, the lead wire 42 is passed through the protective tube 28, and then the resin material is injected into one end 28a of the protective tube 28 to fix the lead wire 42 to the protective tube 28. Finally, the resin material is applied so as to cover one end 28a of the protective tube 28. In this manner, the resin layer 26 can be formed.

[0040] (Action and effect) In the test piece 100 according to this embodiment, the metal foil 22 is adhered to the surface 12a of the clip 12 so as to cover the detection unit 40 and the connection portion of the lead wire 42 with the detection unit 40 (hereinafter referred to as the detection unit 40, etc.). Furthermore, a resin layer 26 is formed so as to cover the boundary portion between the outer edge of the metal foil 22 and the surface 12a of the clip 12. With this configuration, the detection unit 40, etc. can be appropriately protected from the corrosive environment when a test is performed in the corrosive environment.

[0041] In addition, the metal foil 22 can be fixed to the clip 12 by the adhesive layer 24, eliminating the need for high-temperature processing as in the case of forming metal plating. This makes it possible to prevent the sensor 14 (detection unit 40) from deteriorating when the metal foil 22 is fixed to the clip 12.

[0042] Moreover, the adhesive layer 24 is formed so as to surround the detection portion 40. In other words, the detection portion 40 is not covered by the adhesive layer 24. This makes it possible to prevent a decrease in performance of the detection portion 40. For example, when a strain gauge is used as the sensor 14, the deformation of the detection portion 40 is not inhibited by the adhesive layer 24, so that the deformation of the clip 12 can be appropriately detected.

[0043] In this embodiment, the central portion of the metal foil 22 is exposed from the resin layer 26. In this case, an increase in the rigidity of the clip 12 can be suppressed compared to a case in which the resin layer 26 is formed so as to cover the entire metal foil 22. This allows the clip 12 to be deformed appropriately.

[0044] In this embodiment, the detection unit 40 is disposed in the gap 18 between the surface 12a of the clip 12 and the metal foil 22. In this case, the deformation of the detection unit 40 is not hindered compared to when the metal foil 22 is in close contact with the surface 12a of the clip 12 and the detection unit 40. This makes it possible to prevent the performance of the detection unit 40 from deteriorating.

[0045] In this embodiment, the metal foil 20 is provided so as to cover a part of the lead wire 42 at a position away from the detection unit 40, and in the length direction of the lead wire 42, one end side of the metal foil 20 is covered by the metal foil 22, and the other end side is inserted into the protective tube 28. Furthermore, the resin layer 26 is formed so as to cover the part of the metal foil 20 exposed from the metal foil 22 and the protective tube 28, and to close one end 28a (the opening on the detection unit 40 side) of the protective tube 28. With this configuration, the lead wire 42 can be sufficiently protected from the corrosive environment.

[0046] (Modification) In the above embodiment, a case has been described in which one detection unit 40 is provided on the clip 12, but a plurality of detection units 40 may be provided on the clip 12.

[0047] In the above embodiment, the detection unit 40 and the protective structure 16 are provided on the outer surface 12a of the clip 12, but the detection unit and the protective structure may be provided on the inner surface 12b (see FIG. 3) of the clip 12. For example, the detection unit and the protective structure may be provided on each of the surfaces 12a and 12b of the clip 12. In this case, the lead wire connected to the detection unit on the inner side of the clip 12 and the lead wire connected to the detection unit on the outer side of the clip 12 may be passed through a common protective tube.

[0048] In the above embodiment, the sensor 14 and the protective structure 16 are provided on the substantially C-shaped clip 12, but the present invention can be used in tests using various known clips.

[0049] In the above embodiment, the case where the sensor 14 and the protective structure 16 are provided on the clip 12 has been described, but the sensor and the protective structure may be provided on the test piece. For example, the present invention may be used when performing a tensile fatigue test by the back gauge method using the above-mentioned test piece 10. Specifically, a sensor may be provided on the side surface 10b of the test piece 10 (see FIG. 1: the surface on the crack propagation direction side as viewed from the notch 10a) and a protective structure may be provided to protect the sensor. In addition, the test piece to which the present invention is applied is not limited to a CT test piece. For example, when measuring the strain of a rod-shaped test piece, a strain gauge may be protected by the protective structure according to the present invention.

[0050] In the above embodiment, the case where the strain gauge is provided on the clip 12 or the test piece 10 has been described, but other known sensors such as a temperature sensor may also be provided on the clip or the test piece.

[0051] In the above embodiment, the central portion of the metal foil 22 is exposed to the outside, but the central portion of the metal foil 22 may be covered by a resin layer. Specifically, as shown in FIG. 4, a second resin layer 30 having water resistance may be provided so as to cover the portion of the metal foil 22 exposed from the resin layer 26. In the example shown in FIG. 4, the second resin layer 30 is provided so as to cover the entire resin layer 26 and the central portion of the metal foil 22 (the portion exposed from the resin layer 26). It is preferable that the second resin layer 30 has shrinkability. The second resin layer 30 is formed, for example, by applying a paint containing a vinyl chloride resin and a toluene-based solvent once or multiple times. For example, Melcoat (registered trademark) manufactured by Washin Chemical Industry Co., Ltd. can be used as the paint for forming the second resin layer 30.

[0052] Although not shown, a resin layer having water resistance and shrinkability may be formed in the gap 18 between the surface 12a of the clip 12 and the metal foil 22. Specifically, the resin layer may be formed so as to cover the detection unit 40 within the gap 18. In this case, the resin layer may be formed of the same material as the second resin layer 30 described above. [Industrial Applicability]

[0053] As described above, according to the present invention, it is possible to prevent deterioration of a sensor attached to a measurement object, and therefore the present invention can be suitably used when performing fatigue testing in a severe corrosive environment such as a wet hydrogen sulfide environment. [Explanation of symbols]

[0054] 10 Test Pieces 12 Strain gauge 14 Sensors 16 Protective structure 18 void 20,22 Metal foil 24 Adhesive layer 26,30 Resin layer 28 Protective tube 40 Detection unit 42 Lead Wire 100 test specimens

Claims

1. A protective structure for protecting a sensor having a detection unit attached to a surface of a measurement target and a lead wire connected to the detection unit, A first metal foil provided so as to cover the detection portion and at least a connection portion of the lead wire with the detection portion; A first resin layer formed so as to cover a boundary portion between an outer edge of the first metal foil and the surface of the object to be measured, A protective structure for a sensor, wherein the first metal foil is adhered to the surface of the object to be measured by an adhesive layer formed outside the detection portion so as to surround the detection portion.

2. The sensor protection structure according to claim 1 , wherein a gap is formed between the first metal foil and the surface of the object to be measured.

3. a protective tube made of resin and provided so that the lead wire passes through the inside of the protective tube; a second metal foil wrapped around the lead wire so as to cover a portion of the lead wire at a position away from the detection unit; One end side of the second metal foil in the length direction of the lead wire is covered with the first metal foil, and the other end side of the second metal foil in the length direction of the lead wire is inserted into the protective tube, The sensor protection structure according to claim 1 , wherein the first resin layer is formed to cover a portion of the second metal foil exposed from the first metal foil and the protective tube, and to block an opening of the protective tube on the detection portion side.

4. Further comprising a second resin layer made of a resin different from the first resin layer, the first resin layer is formed such that a central portion of the first metal foil is exposed from the first resin layer; The sensor protection structure according to claim 1 , wherein the second resin layer is formed so as to cover the first resin layer and the first metal foil at portions exposed from the first resin layer.

5. the sensor is a strain gauge; 2. The protective structure for a sensor according to claim 1, wherein the measurement target is a test piece or a clip attached to the test piece.

6. A method for attaching a sensor having a detection unit and a lead wire connected to the detection unit to a measurement target, comprising the steps of: A step of attaching the detection unit to a surface of the measurement object; A method of mounting a sensor comprising the steps of: forming the protective structure of claim 1 .

7. a test specimen or a clip attached to the test specimen; a sensor for measuring the test piece or the clip, the sensor having a detection unit attached to a surface of the measurement object and a lead wire connected to the detection unit; A test specimen comprising the protective structure according to claim 1 .

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