WO2020121420A1

WO2020121420A1 - Strain detection device

Info

Publication number: WO2020121420A1
Application number: PCT/JP2018/045564
Authority: WO
Inventors: 栄今田; 西田　秀高; 昭典吉光; 和成大櫃; 一弘木村; 浩太澤田
Original assignee: 中国電力株式会社; 国立研究開発法人物質・材料研究機構
Priority date: 2018-12-11
Filing date: 2018-12-11
Publication date: 2020-06-18
Also published as: JPWO2020121420A1; JP6547994B1

Abstract

Provided is a strain detection device capable of suppressing error in the measurement of the strain of an object under test. This strain measurement device 1 comprises: a main breaking detection member 11 having a small-diameter part 114 that can be broken by the application of tensile stress in a first direction D0; a conducting part 131 provided in a region straddling the small-diameter part 114; a first holding member 12A for holding a first end part of the main breaking detection member 11; and a second holding member 12B for holding a second end part of the main breaking detection member 11. The first end part and second end part each have a touching part 115. The first holding member 12A and second holding member 12B each have a touched part 126 opposing the touching part 115 corresponding thereto. The touching parts 115 are mounted on an object under test in a state where the touching parts 115 are removed from the touched parts 126.

Description

Strain detector

The present invention relates to a strain detection device.

Conventionally, there is known a strain detection device which is provided on the surface of a measurement target and detects a strain by breaking a detection unit (for example, Patent Document 1). Specifically, the strain detection device described in Patent Document 1 includes a thin film substrate attached to the surface of the measurement target, and a sensor foil provided on the thin film substrate. The sensor foil has a narrow easy-to-break portion at the center in the longitudinal direction. When the object to be measured is distorted, the sensor foil stretches in the longitudinal direction and the easily breakable portion breaks, so that the strain is detected.

International publication WO2008/013049

However, when the strain detection device is attached when the temperature of the measurement target is low, the strain amount when the temperature of the measurement target becomes high includes not only the strain amount due to the creep phenomenon but also the elongation amount due to thermal expansion. It becomes a numerical value. As described above, in the strain measurement by the strain detection device described in Patent Document 1, a measurement error may occur due to thermal expansion of the measurement target.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a strain detection device capable of suppressing a measurement error.

The strain detecting device according to the present invention is provided in a breakage detection main member having a breakable easy portion that can be broken when tensile stress is applied in the first direction, and in a portion across the breakable easy portion in the breakage detection main member. A breakage detection unit, a first holding member that is fixed to a first portion of the detected body, and holds a first end of the breakage detection main member, and a second portion of the detected body that detects the breakage. A second holding member that holds a second end portion of the main member, wherein the first end portion and the second end portion each have an abutting portion, and the first holding member and the second holding member And at least one of the first holding member and the second holding member, the abutting portion facing the abutting portion, the abutting portion being separated from the abutting portion. It is installed on the detector.

According to the present invention, it is possible to reduce distortion measurement error.

FIG. 1 is a schematic view showing a cross section of a strain detecting device and a boiler pipe provided with the strain detecting device according to a first embodiment of the present invention. FIG. 2 is a sectional view taken along line II-II of FIG. FIG. 3 is a sectional view in which a part of FIG. 2 is enlarged. FIG. 4 is a perspective view of the breakage detection main member according to the first embodiment. FIG. 5 is a perspective view of the holding member according to the first embodiment. FIG. 6 is an enlarged cross-sectional view of a part of FIG. 2, showing a state in which the holding member moves. FIG. 7 is a partially enlarged cross-sectional view of the strain detection device according to the second embodiment. FIG. 8 is a schematic diagram of the strain detection device according to the third embodiment as viewed from above. FIG. 9 is a schematic view of the strain detection device according to the fourth embodiment as viewed from the side. FIG. 10 is a schematic diagram showing a cross section of a strain detecting device and a detected body provided with the strain detecting device according to the fifth embodiment. FIG. 11 is a perspective view of the breakage detection main member according to the sixth embodiment. FIG. 12 is a schematic view of the strain detection device according to the sixth embodiment as viewed from above.

Each embodiment of the present invention will be described below with reference to the drawings. It should be noted that the disclosure is merely an example, and a person having ordinary skill in the art can easily think of an appropriate modification while keeping the gist of the invention, and is naturally included in the scope of the invention. Further, in order to make the description clearer, the drawings may schematically show the width, thickness, shape, etc. of each part as compared with the actual mode, but this is merely an example, and the interpretation of the present invention will be understood. It is not limited.

Also, in this specification and each drawing, elements similar to those described above in regard to a drawing thereinabove are designated by the same reference numerals, and detailed description thereof may be appropriately omitted. In the following description, the first direction D0, which is the extending direction of the detected object, is also referred to as the longitudinal direction. Of the first direction D0, the right direction in FIGS. 1 and 2 is referred to as a first extending direction D1, and the left direction in FIGS. 1 and 2 is referred to as a second extending direction D2.

[First Embodiment]
First, a first embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing a cross section of a strain detecting device 1 according to a first embodiment of the present invention and a boiler pipe 2 (object to be detected) provided with the strain detecting device 1.

The strain detection device 1 according to the first embodiment is applied, for example, when detecting the strain of a welded portion such as the boiler pipe 2 of a thermal power plant, but the strain detection device 1 detects the strain. Not limited to. That is, this embodiment will be described as an example in which the boiler pipe 2 is applied as the detected object. The boiler pipe 2 includes a first base material 21 (first portion of the detected body), a second base material 22 (second portion of the detected body), a first base material 21 and a second base material 22. And a welded portion 23 for joining. The first base material 21 and the second base material 22 are, for example, high chromium ferritic steel pipes. The weld 23 includes a weld metal 24 and a heat-affected zone 25. The weld metal 24 is, for example, high chromium ferritic steel. The heat-affected zone 25 is located between the first base material 21 and the weld metal 24. The heat-affected zone 25 is a portion affected by heat when the first base material 21 and the second base material 22 are welded together with the weld metal 24. The heat-affected zone 25 differs from the first base material 21, the second base material 22, and the weld metal 24 in mechanical properties and the like. In a metal member, a metal product, etc., if a state where a constant load is applied continues for a long time, a creep phenomenon in which deformation of the metal member or the like increases may occur. In particular, since the welded portion 23 is likely to break due to the creep phenomenon, in the present embodiment, the welded portion 23 is the target portion for strain measurement.

The strain detection device 1 is provided on the surface 2 a of the boiler pipe 2. Specifically, the strain detection device 1 extends along the extension direction (first direction D0) of the boiler pipe 2. The first holding member 12A and the second holding member 12B included in the strain detection device 1 are fixed to the surface 2a of the boiler pipe 2 by welding or the like. The first holding member 12A and the second holding member 12B are arranged across the welded portion 23. Specifically, the first holding member 12A is fixed to the first base material 21 (first portion of the detected object). The second holding member 12B is fixed to the second base material 22 (the second portion of the detected object).

2 is a sectional view taken along the line II-II in FIG. FIG. 3 is a sectional view in which a part of FIG. 2 is enlarged. FIG. 4 is a perspective view of the breakage detection main member 11 according to the first embodiment. FIG. 5 is a perspective view of the holding member 12 according to the first embodiment.

As shown in FIG. 2, the strain detection device 1 includes a fracture detection main member 11, a first holding member 12A and a second holding member 12B, and a fracture detection device 13.

As shown in FIG. 4, the breakage detection main member 11 includes a plurality of cylindrical parts having a central axis AX along the longitudinal direction. Specifically, the plurality of columnar portions include a large diameter portion 110A (first end portion), a large diameter portion 110B (second end portion), and a small diameter portion 111. As the material of the breakage detection main member 11, ceramic or the like that is easily brittle and breakable can be applied.

The large-

diameter portions

110A and 110B are end portions in the extension direction (first direction D0) of the fracture detection main member 11. Specifically, the first end portion arranged on the right side (first expansion direction D1 side) of FIGS. 1, 2, and 4 is the large diameter portion 110A. The second end portion arranged on the left side (the second extending direction D2 side) of FIGS. 1, 2, and 4 is the large diameter portion 110B. The large diameter portion 110A (first end portion) is held by the first holding member 12A. The large diameter portion 110B (second end portion) is held by the second holding member 12B. The

large diameter parts

110A and 110B have a column part 112 and a taper part 113. The column portion 112 is a column having the same diameter that extends along the longitudinal direction from the outer edge 116 in the longitudinal direction to the tip 117 on the central side in the longitudinal direction. The taper portion 113 extends from the tip 117 to the end edge 118 on the longitudinal center side.

The outer diameter of the taper portion 113 increases in the first direction D0 (extension direction). That is, in the taper portion 113 on the right side of FIG. 4, the outer diameter increases in the first extending direction D1. In the taper portion 113 on the left side of FIG. 4, the outer diameter increases in the second extending direction D2. The taper portion 113 is a contact portion 115 that can contact the contacted portions 126 of the first holding member 12A and the second holding member 12B, which will be described later.

The small-diameter portion 111 extends along the longitudinal direction so as to connect the edges 118 of the pair of tapered portions 113 that are separated from each other in the longitudinal direction (first direction D0). The small diameter portion 111 has a smaller diameter than the columnar portion 112. The small-diameter portion 111 has a small-diameter portion 114 (easily breakable portion) that is locally formed with a small outer diameter. The small-diameter portion 114 is a portion where the tips of a pair of truncated cones are joined together. The breakable portion may be, for example, a notch or notch other than the small diameter portion 114.

As shown in FIG. 2, the breakage detection device 13 includes a conduction part 131 (breakage detection part) and a detector 133 connected to the lead wire 132. The conducting portion 131 is a coating layer that covers the outer peripheral surface of the small-diameter portion 111 including the small-diameter portion 114 (easy-to-break portion) in the central portion in the longitudinal direction. The conducting portion 131 is also called a breakage detecting portion. That is, the conduction portion 131 (breakage detection portion) is provided in a portion of the breakage detection main member 11 that straddles the small-diameter portion 114 (breakable portion). The conducting portion 131 is capable of conducting, and when the small diameter portion 114 is broken, the conducting portion 131 can also be broken together with the small diameter portion 114. The conductive portion 131 is provided as a coating layer by, for example, thermally spraying or vapor depositing a metal on the outer peripheral surface of the small diameter portion 111. Two lead wires 132 are connected to both ends in the longitudinal direction of the conducting portion 131, and the lead wires 132 are connected to the detector 133.

In a normal state (when not breaking), the conducting portion 131 is not broken, so that the current from the detector 133 energizes the conducting portion 131 via one lead wire 132 and the other lead wire 132 to the detector 133. Return to. In this case, it is determined that the breakage detection main member 11 is not broken. When the conductive portion 131 is broken, the break detection main member 11 is also broken, so that the current from the detector 133 does not pass through the conductive portion 131. It is detected that the breakage detection main member 11 is broken due to this imperfect conduction. As described above, in the breakage detection device 13, when the conduction part 131 (breakage detection part) is broken and a current flow failure occurs, it is determined that the breakage detection main member 11 is broken.

As shown in FIG. 5, the first holding member 12A has a base 121 and a lid 122. The first holding member 12A is fixed to the surface 2a of the boiler pipe 2 as shown in FIG. Specifically, the first holding member 12A is fixed to the surface 2a of the boiler pipe 2 located on both sides of the welded portion 23 in the longitudinal direction by welding or the like. As shown in FIG. 5, the base 121 is a box-shaped member, and a recess 123 is provided inside. The large-diameter portion 110A of the breakage detection main member 11 is housed in the recess 123. The upper opening is sealed by a lid 122 and fastened with a bolt or the like (not shown). As shown in FIG. 3, a U-shaped opening 124 is provided on the inner peripheral surface of the recess 123 on the longitudinal center side (front side in FIG. 5 ). The second holding member 12B also has the same structure as the first holding member 12A.

As shown in FIG. 3, the inner peripheral surface near the opening 124 is formed as a tapered portion 125. The tapered portion 125 has an inner diameter that increases toward the first direction D0 (first extending direction D1). The tapered portion 125 extends along the tapered portion 113 of the large diameter portion 110A. More specifically, the tapered portion 125 extends parallel to the tapered portion 113 of the large diameter portion 110A. The tapered portion 125 is a contacted portion 126 that is arranged so as to face the contact portion 115. Further, the tapered portion 113 (contact portion 115) and the tapered portion 125 (contacted portion 126) are separated from each other in the longitudinal direction. A gap G1 along the longitudinal direction is provided between the tapered portion 113 (abutting portion 115) and the tapered portion 125 (abutted portion 126).

Next, a change in the relative position between the large diameter portion 110A of the breakage detection main member 11 and the first holding member 12A due to the movement of the first holding member 12A will be described. FIG. 6 is an enlarged cross-sectional view of a part of FIG. 2, showing a state in which the first holding member 12A moves.

First, as shown in FIG. 1, an initial state in which the strain detection device 1 is fixed to the surface 2a of the boiler pipe 2 will be described. As shown in FIG. 6, the radially inner tip 126a of the contacted portion 126 of the first holding member 12A is located at the first position P1 along the longitudinal direction (first direction D0). At the first position P1, the tip 126a of the contacted portion 126 is in a state of being separated from the contact portion 115 along the longitudinal direction by the distance ds1.

At this time, the length of the tip of the contacted portion 126 of the second holding member 12B shown on the left side of FIG. 1 and the tip of the contacted portion 126 of the first holding member 12A shown on the right side (tip 126a shown in FIG. 6). The distance along the direction is L1. Although not shown in the present embodiment, in order to facilitate understanding of the description, in the second holding member 12B shown on the left side of FIG. 1, the contact portion 115 and the contacted portion 126 are in contact with each other, In the first holding member 12A shown on the right side of FIG. 1, it is assumed that the contact portion 115 and the contacted portion 126 are separated from each other.

Next, when the boiler pipe 2 shown in FIG. 1 extends in the longitudinal direction, the distance between the first holding member 12A and the second holding member 12B also increases. Then, the tip 126a of the contacted portion 126 shown in FIG. 6 moves in the first extending direction D1 by the distance ds1 and is located at the second position P2 shown by the chain double-dashed line. At the second position P2, the tip 126a of the contacted portion 126 and the contact portion 115 are in contact with each other. At this time, the length of the tip of the contacted portion 126 of the second holding member 12B shown on the left side of FIG. 1 and the tip of the contacted portion 126 of the first holding member 12A shown on the right side (tip 126a shown in FIG. 6). The distance along the direction is L2.

Further, when the boiler pipe 2 shown in FIG. 1 further extends in the longitudinal direction, the distance between the first holding member 12A and the second holding member 12B also increases. Then, the tip 126a of the contacted portion 126 shown in FIG. 6 further moves from the second position P2 toward the first extension direction D1 by the distance ds2 and is located at the third position P3 shown by the broken line. At the third position P3, the tip of the contacted portion 126 of the second holding member 12B shown on the left side of FIG. 1 and the tip of the contacted portion 126 of the first holding member 12A shown on the right side (tip 126a shown in FIG. 6). ) Along the longitudinal direction is L3.

Here, since the contact portion 115 and the contacted portion 126 are in contact with each other at the second position P2, the contact portion 115 of the breakage detection main member 11 also extends from the second position P2 by the distance ds2 in the extending direction. It moves to the (1st extension direction D1 side), and is located in the 3rd position P3 shown with a broken line. That is, at the third position P3, the amount of extension of the fracture detection main member 11 along the longitudinal direction is the distance ds2. When the amount of elongation when the small diameter portion 114 of the breakage detection main member 11 breaks is set to the distance ds2, the breakage detection main member 11 breaks at the third position P3. Then, as described above, the conduction portion 131 is also fractured to cause defective conduction, and the fracture detection device 13 detects that the fracture detection main member 11 is fractured. Since the first holding member 12A moves from the first position P1 to the third position P3, the total movement length is ds3, which is a combination of ds1 and ds2.

As described above, in the strain detection device 1 according to the present embodiment, the first holding member 12A has the contacted portion 126 facing the contact portion 115 provided at the end of the fracture detection main member 11. Have. The contact portion 115 and the contacted portion 126 were installed in the boiler pipe 2 in a state of being separated from each other along the first direction D0.

As described above, the contact portion 115 and the contacted portion 126 are installed in the boiler pipe 2 in the state of being separated from each other along the first direction D0, so that the strain measurement error of the boiler pipe 2 is reduced. Can be reduced.

The following is a specific explanation. The boiler pipe 2 of the thermal power plant becomes high temperature and thermally expands when the power generator operates. Therefore, when the first holding member 12A and the second holding member 12B are fixed to the boiler pipe 2 while the boiler pipe 2 is at room temperature, the contact between the contacted portion 126 and the contact portion 115 and the contacted portion 126A. When the power generator operates and the boiler pipe 2 is heated in a state where no gap is provided between the contact portion 115A and the contact portion 115A, the contact portion 115 of the breakage detection main member 11 is not covered by the holding member 12. It may have already been pulled by the abutment 126. As described above, it is conceivable that tensile stress is already applied to the breakage detection main member 11 before the strain is detected. Therefore, originally, for example, the breakage detection main member 11 breaks when the boiler pipe 2 extends by 10 mm, for example, whereas the breakage detection main member 11 may break at an extension of 5 mm. In this case, since a measurement error will occur, it will be difficult to accurately detect the amount of distortion. As described above, the abutting portion 115 and the abutted portion 126 are installed in the boiler pipe 2 in a state of being separated along the first direction D0, thereby reducing the measurement error of the strain measurement. it can.

The abutting portion 115 and the abutted portion 126 are separated from each other along the first direction D0 when installed in the boiler pipe 2. Therefore, even when the power generator operates and the temperature of the boiler pipe 2 becomes high, the contact portion 115 and the contacted portion 126 move in the first direction D0 until a predetermined distortion due to the creep phenomenon of the boiler pipe 2 occurs. Are separated along. Then, when a predetermined strain due to the creep phenomenon of the boiler pipe 2 occurs and the abutting portion 115 and the abutted portion 126 come into contact with each other, the strain detecting device 1 can properly perform the strain detection.

In addition, the distance between the first holding member 12A and the second holding member 12B is the same as that of the first holding member 12A in the state where the first holding member 12A and the second holding member 12B are installed in the boiler pipe 2 in a state where the contact portion 115 is separated from the contacted portion 126. When it becomes larger than the distance L1 from the second holding member 12B, the contact portion 115 and the contacted portion 126 contact each other.

When the distance between the contact portion 115 and the contacted portion 126 in the state where the strain detecting device 1 is installed in the boiler pipe 2 is too large, the contact portion 115 causes the contact portion 115 to contact even if the boiler pipe 2 creeps. It is possible that it does not contact 126. Therefore, by installing the strain detection device 1 in the boiler pipe 2 with the separation distance between the contact portion 115 and the contacted portion 126 set to an appropriate distance, the contact portion 115 contacts the contacted portion 126. In contact, appropriate distortion detection can be performed.

The breaking detection main member 11 includes a columnar portion having a central axis AX along the longitudinal direction. Therefore, since the fracture detection main member 11 has a shape that is symmetrical in the radial direction about the central axis AX, the stress applied to the fracture detection main member 11 is uniform in the radial direction. Here, when the stress applied to the breakage detection main member 11 is uneven in the radial direction, it is possible that the breakage detection main member 11 breaks at a value smaller than the original elongation amount. Therefore, in this embodiment, accurate strain detection can be performed.

The columnar portion of the breakage detection main member 11 has a larger diameter than the

large diameter portions

110A and 110B that are ends held by the holding member 12 and the

large diameter portions

110A and 110B that extend in the longitudinal direction from the

large diameter portions

110A and 110B. And a small small diameter portion 111. In this way, the large-

diameter portions

110A and 110B are held by the holding member 12, and the small-diameter portion 111 is broken, so that the fracture detecting main member 11 having a simple structure can have a necessary function.

The contact portion 115 has a tapered portion 113 whose outer diameter increases toward the first direction D0 (stretching direction), and the contacted portion 126 has a larger inner diameter toward the first direction D0 (stretching direction). Has a tapered portion 125.

As described above, since the contact portion 115 and the contacted portion 126 both have the tapered

portions

113 and 125, the fracture detecting main member 11 receives a load over a wide area. Therefore, the fracture detection main member 11 can receive the load evenly on the entire abutting portion 115, so that accurate strain detection can be performed as compared with the case where the load is locally received.

The breaking detection main member 11 has a small diameter portion 114 (easy breaking portion). Therefore, as compared with the case where the small diameter portion 114 is not provided, the breakage detection main member 11 can be broken more reliably with a small tensile stress.

The breakage detection main member 11 has a conductive portion 131 that is covered by the outer peripheral surface of the small-diameter portion 114 (easy-to-break portion) so as to be conductive and that can be broken together with the small-diameter portion 114 (easy-to-break portion).

Therefore, since the breakage of the breakage detection main member 11 is detected by the breakage of the conductive portion 131 together with the small-diameter portion 114 (easy-to-break part), the breakage detection main member 11 can be broken at a low cost and with a simple structure. Detected.

[Second Embodiment]
Next, a second embodiment of the present invention will be described. FIG. 7 is an enlarged cross-sectional view of a part of the strain detection device 1A according to the second embodiment.

As shown in FIG. 7, in the strain detection device 1A according to the second embodiment, the fracture detection main member 11A has a large diameter portion 110C and a small diameter portion 111A. The end surface of the large-diameter portion 110C on the center side in the longitudinal direction is formed as a flat portion 113A. The flat portion 113A is a flat surface that extends in the radial direction orthogonal to the central axis AX. The flat portion 113A is the contact portion 115A.

The third holding member 12C has a flat portion 125A that faces the flat portion 113A of the breakage detection main member 11A and is spaced apart therefrom. The flat portion 125A is a flat surface that extends in the radial direction orthogonal to the central axis AX. The flat portion 125A is the contacted portion 126A. A gap G1 is provided between the flat portion 113A (abutting portion 115A) and the flat portion 125A (abutted portion 126A) so as to be separated along the longitudinal direction.

As described above, according to the present embodiment, the contact portion 115A and the contacted portion 126A extend in the radial direction of the fracture detection main member 11A at a right angle (intersection) to the central axis AX.

Therefore, it becomes easy to accurately measure the distance along the longitudinal direction between the contact portion 115A and the contacted portion 126A.

[Third Embodiment]
Next, a third embodiment of the present invention will be described. FIG. 8 is a schematic diagram of the strain detection device 1B according to the third embodiment as viewed from above.

As shown in FIG. 8, a strain detection device 1B according to the third embodiment is a unit in which a plurality of strain detection devices 1 described in the first embodiment are arranged in parallel. Specifically, the parallel direction of the strain detectors 1 is a direction orthogonal (intersecting) to the longitudinal direction (first direction D0) and is a direction along the surface 2a of the boiler pipe 2. In this embodiment, the three strain detection devices 1 are arranged in parallel, and the respective first holding member 12A and second holding member 12B are fixed to the surface 2a of the boiler pipe 2.

As described above, the strain detection device 1B according to the present embodiment is orthogonal to (intersects) the strain detection device 1 described in the first embodiment in the longitudinal direction (first direction D0), and the front surface 2a of the boiler pipe 2. A plurality of them are arranged side by side in the parallel direction.

Therefore, since the average value obtained by averaging the detection values of the plurality of strain detection devices 1 is obtained, it is possible to obtain a more accurate detection value than the detection value of one strain detection device 1.

[Fourth Embodiment]
Next, a fourth embodiment of the present invention will be described. FIG. 9 is a schematic view of the strain detection device 1C according to the fourth embodiment as viewed from the side.

As shown in FIG. 9, the strain detection device 1C according to the fourth embodiment is a unit in which a plurality of strain detection devices 1 described in the first embodiment are stacked and arranged. Specifically, the stacking direction of the strain detection device 1 is a direction orthogonal (intersecting) to the longitudinal direction (first direction D0) and is a direction away from the surface 2a of the boiler pipe 2.

In this embodiment, the three strain detection devices 1 are vertically stacked, and the lowermost holding member 12 is fixed to the surface 2 a of the boiler pipe 2. That is, the holding member 12 of the strain detection device 1 on the lowest side (lowermost side) is fixed to the surface 2 a of the boiler pipe 2. The holding member 12 of the strain detection device 1 which is the second from the bottom (the center side in the vertical direction) is fixed on the holding member 12 of the strain detection device 1 that is the lowest side. The holding member 12 of the third (uppermost) strain detecting device 1 from the bottom is fixed on the second holding member 12 of the strain detecting device 1 (downward in the vertical direction).

As described above, a plurality of the strain detection devices 1 described in the first embodiment are stacked in the height direction orthogonal to (intersecting) the longitudinal direction (first direction D0) and away from the surface 2a of the boiler pipe 2. As a result, the strain detection device 1C according to this embodiment is configured.

Therefore, for example, by changing the separation distance between the contact portion 115 and the contacted portion 126 along the longitudinal direction in order from the lower device to the upper device, it is possible to detect a more accurate strain amount. For example, the separation distance of the first device from the bottom is 10 mm, the separation distance of the second device from the bottom is 20 mm, and the separation distance of the third device from the bottom is 30 mm. Note that if the material is made of ceramic or the like and set so that it breaks with almost no elongation, when the breaking detection main member 11 of the second device from the bottom breaks, the amount of strain should be between 20 mm and 30 mm. I understand.

[Fifth Embodiment]
Next, a fifth embodiment of the present invention will be described. FIG. 10: is a schematic diagram which shows the cross section of the distortion detection apparatus 1D which concerns on 5th Embodiment, and the boiler piping 2 in which the distortion detection apparatus 1D was provided.

In the first embodiment shown in FIG. 1, the first holding member 12A and the second holding member 12B are arranged across the welded portion 23. However, in the strain detector 1D according to the fifth embodiment, the holding member 12D on the right side of FIG. 10 is fixed on the welded portion 23 (specifically, on the weld metal 24), and the holding member 12D on the left side is boiler. You may fix on the surface 2a of the piping 2. The strain detection device 1D includes a breakage detection main member 11D.

As described above, according to the present embodiment, the strain detection device 1D can be installed even in a place where it is difficult to dispose the welded portion 23.

[Sixth Embodiment]
Next, a sixth embodiment of the present invention will be described. FIG. 11 is a perspective view of the breakage detection main member according to the sixth embodiment. FIG. 12 is a schematic view of the strain detection device according to the sixth embodiment as viewed from above.

As shown in FIG. 11, the breakage detection main member 11E according to the sixth embodiment has a flat plate shape formed to have substantially the same thickness throughout. The breakage detection main member 11E has a wide portion 110E (first end portion), a narrow portion 111E, and a wide portion 110F (second end portion).

The width of the wide portion 110E in the direction orthogonal to the central axis AX is larger than the width of the narrow portion 111E. The width of the wide portion 110F in the direction orthogonal to the central axis AX is larger than the width of the narrow portion 111E. The width of the wide portion 110E is substantially the same as the width of the wide portion 110F.

The end surface on the longitudinal center side of the wide portion 110E is formed as a curved surface 113E. The curved surface 113E is formed in a shape curved in an arc shape in a plan view. The curved surface 113E is the contact portion 115E. An end surface of the wide portion 110F on the center side in the longitudinal direction is formed as a curved surface 113F. The curved surface 113F is formed in a shape curved in an arc shape in a plan view. The curved surface 113F is the contact portion 115E. As the material of the breakage detection main member 11E, ceramic or the like which is easily brittle and broken can be applied.

As shown in FIG. 12, the strain detection device 1E includes a fracture detection main member 11E, a first holding member 12E and a second holding member 12F, and a fracture detection device 13.

The

wide portions

110E and 110F are end portions in the extension direction (first direction D0) of the fracture detection main member 11E. Specifically, the first end portion arranged on the right side (the first extending direction D1 side) in FIG. 12 is the wide portion 110E. The second end portion arranged on the left side (the second extending direction D2 side) of FIG. 12 is the wide portion 110F. The wide portion 110E (first end portion) is held by the first holding member 12E. The wide portion 110F (second end portion) is held by the second holding member 12F.

The abutted portion 126E is provided on the first holding member 12E. The contacted portion 126E is arranged so as to face the curved surface 113E (contact portion 115E) of the breakage detection main member 11E. The contacted portion 126E has an arcuate shape that is convex toward the curved surface 113E. The curved surface 113E (contact portion 115E) has an arcuate shape that is recessed in a direction away from the contacted portion 126E. That is, the contacted portion 126E is formed to be curved along the curved surface 113E.

The abutted portion 126E is provided on the second holding member 12F. The contacted portion 126E is arranged to face the curved surface 113F (contact portion 115E) of the breakage detection main member 11E. The contacted portion 126E has an arcuate shape that is convex toward the curved surface 113F. The curved surface 113F (contact portion 115E) has an arcuate shape that is recessed in a direction away from the contacted portion 126E. That is, the contacted portion 126E is formed to be curved along the curved surface 113F. The

curved surfaces

113E and 113F (contact portion 115E) and the contacted portion 126E are separated from each other along the first direction D0.

As described above, the breakage detection main member 11E according to the present embodiment has a flat plate shape formed with substantially the same thickness throughout. The contact portion 115E and the contacted portion 126E were installed in the boiler pipe 2 in a state of being separated along the first direction D0.

In this way, even in the breakage detection main member 11E having the shape of a flat plate formed to have substantially the same thickness over the whole, the contact portion 115E and the contacted portion 126E are separated from each other along the first direction D0. When the boiler pipe 2 is installed in such a state, the strain measurement error of the boiler pipe 2 can be reduced.

The specific configuration of the strain detection device in the above embodiment is merely an example, and the present invention is not limited to this, and can be appropriately changed.

For example, in the first embodiment, only in the first holding member 12A, the contact portion 115 is installed in the boiler pipe 2 in a state of being separated from the contacted portion 126. However, in both the first holding member 12A and the second holding member 12B, the contact portion 115 may be installed in the boiler pipe 2 in a state of being separated from the contacted portion 126.

Further, in the strain detection device 1B according to the third embodiment, although the three strain detection devices 1 are arranged in parallel, the number may be two or four or more. Furthermore, although the strain detection device 1C according to the fourth embodiment has three strain detection devices 1 stacked in the vertical direction, the number may be two or four or more.

1, 1A, 1B, 1C, 1D, 1E Strain detection device 2 Boiler piping (detected object)
11, 11A, 11D, 11E Fracture detection main member 12A First holding member 12B Second holding member 21 First base material (first portion)
22 Second base material (second part)
115, 115A,

115E Abutting part

126, 126A, 126E Abutted part 110A Large diameter part (first end part, column part)
110B Large diameter part (2nd end, cylindrical part)
110E Wide part (first end)
110F Wide part (2nd end)
111,111A Small diameter part (cylindrical part)
113, 125 Tapered part 114 Small diameter part (easy to break part)
131 Conducting part (breakage detecting part)
AX Central axis D0 First direction

Claims

A rupture detection main member having a rupturable easy portion that can be ruptured when tensile stress is applied in the first direction,
A breakage detection portion provided in a portion straddling the breakage easy portion in the breakage detection main member,
A first holding member that is fixed to a first portion of the detected object and holds a first end portion of the breakage detection main member;
A second holding member that is fixed to the second portion of the detected object and holds the second end of the breakage detection main member;
Equipped with
The first end portion and the second end portion each have a contact portion,
Each of the first holding member and the second holding member has an abutted portion facing the abutting portion,
In at least one of the first holding member and the second holding member, the abutting portion is installed on the detected body in a state of being separated from the abutted portion,
Strain detection device.
The distance between the first holding member and the second holding member is the distance between the first holding member and the first holding member in a state where the contact portion is installed on the detected object in a state of being separated from the contacted portion. 2 When the distance from the holding member becomes larger, the contact portion and the contacted portion contact each other,
The strain detection device according to claim 1.
A plurality of the breakage detection main members and the breakage detection unit are arranged in a parallel direction that intersects the first direction and is along the surface of the detected object.
The strain detection device according to claim 1.
A plurality of the first holding member, the second holding member, the breakage detection main member, and the breakage detection unit are arranged in a height direction that intersects with the first direction and moves away from the surface of the detection target.
The strain detection device according to claim 1.
The breakage detection main member includes a columnar portion having a central axis along the first direction,
The strain detection device according to any one of claims 1 to 4.
The columnar portion of the breakage detection main member has a large-diameter portion which is the first end portion and the second end portion held by the first holding member and the second holding member, and is larger than the large-diameter portion. And a small diameter portion having a small diameter,
The strain detection device according to claim 5.
The abutting portion has a taper portion whose outer diameter increases toward the first direction,
The contacted portion has a tapered portion whose inner diameter increases in the first direction,
The strain detection device according to claim 5 or 6.
The abutting portion and the abutted portion extend in the radial direction of the breakage detection main member orthogonal to the central axis.
The strain detection device according to claim 5 or 6.
The strain detection device according to any one of claims 1 to 8, wherein the breakage detection part has a conductive part that is covered by an outer peripheral surface of the breakage detection main member and is conductive, and that can be broken together with the easy breakage part. ..