JP2008046029A - Optical-type vibration strain measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical-type vibration strain measuring device that is applicable also to high-temperature measuring objects, capable of performing strain measurements, including both torsion strain and bending strain, having less noise and high accuracy and reliability, by directly measuring the deformations of a measuring object portion. <P>SOLUTION: Each deformation of at least six spots of the measuring object portion that vibrates is measured, by using at least six laser displacement gauges mounted on one holder, and the strain caused by the vibrational deformations consisting mainly of bending deformation and torsion strain, generated in the measuring object, are calculated by an operation device from the difference between each displacement that has been measured by each laser displacement gauge. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an optical vibration distortion measuring apparatus for measuring strain generated mainly by both bending deformation and torsion deformation, and in particular, at least six vibration displacement detection units are provided in one folder. By adopting a structure in which the laser displacement meter is compactly integrated with two stages arranged and fixed, and a laser beam reflecting jig having planar fins is disposed at the measurement target site, The present invention relates to an optical vibration distortion measuring apparatus that enables simplification, miniaturization, and significant improvement in measurement accuracy.

  Piping, equipment, and the like installed in various plants such as power plants are constantly subjected to complex stresses due to heating and mechanical loads during plant operation, and so-called stress distortion occurs. For example, a vibrating structure, such as a pipe-like structure, is subject to vibration distortion mainly consisting of bending deformation and torsional deformation. In addition to measurement, it is necessary to transmit the measured distortion information to the equipment management system.

  Thus, as a method of measuring the vibration distortion generated in the pipe or the like, a method of attaching a strain gauge directly to a measurement object (Japanese Patent Laid-Open No. 2003-194508), or a number of accelerations A method of attaching a meter to a considerable range including the measurement target part of the measurement target, grasping the deformation state of the measurement target from the measurement value of the accelerometer, and obtaining the distortion generated in the target part by calculation 11-014445 etc.) have been developed.

  However, each measurement method has many difficulties. A large amount of work is required for setting the measuring device, and the amount of work required for the measurement becomes enormous; The method of attaching a strain gauge is noisy and difficult to apply to high-temperature measurement objects. The method using an accelerometer, etc. indirectly grasps the deformation of the measurement object from information including other factors other than the factors affecting the strain to be measured, and calculates the distortion from the grasped deformation. For this reason, there are problems such as large errors and skill required for work.

  On the other hand, in order to solve the problems as described above, for example, data relating to the shape of equipment and devices constituting the operating and stopping plant equipment is acquired using laser light, and preset operating and stopping equipment.・ Calculate the amount of movement from the three-dimensional position evaluation point of the device (reference evaluation point) and the three-dimensional position evaluation point of the device / device that has been operating and stopped after a certain period of time, and the magnitude of the amount of movement A technique for determining the soundness of plant equipment based on the above has been developed (Japanese Patent Laid-Open No. 2001-41717).

  Although the technique disclosed in Japanese Patent Laid-Open No. 2001-41717 has the advantage that it can be applied to equipment and devices such as high radiation dose locations and high places, the measuring device is still complicated and large in size, and many of the measurements themselves are performed. In addition to the time required, there is a problem that the soundness (for example, distortion of piping) of the device / device cannot be continuously monitored with high accuracy only by detecting the three-dimensional position evaluation point of the device being operated or the device.

  Similarly, in order to solve the problems in the case of using the strain gauge or the accelerometer, the amount of elongation or shrinkage between two locations on the sample surface by using the spectrum pattern of laser light or by using the Doppler effect Have been developed (JP-A-7-4928, JP-A-9-297010, JP-A-2001-124516, etc.).

  However, with this type of strain measurement device using conventional laser light, the only measurable strain is the vibration strain mainly consisting of bending deformation, and the torsional deformation is one of the important distortions that occur in the piping system. There is a problem that it cannot cope with vibration distortion mainly composed of.

  Also, in a conventional strain measurement device using a laser displacement meter, when the outer surface of the measurement target part is a curved surface such as a pipe, the laser is used when the pipe vibrates in a direction orthogonal to the measurement direction. Due to the influence of the curved surface on the reflection of light, there is a problem that the measurement error of distortion mainly consisting of bending deformation becomes large.

  Further, this type of strain measurement technique using conventional laser light is simply a parallel arrangement of a plurality of independent laser displacement meters, for example, two laser displacement meters are arranged in parallel. In this case, it is inevitable that measurement errors occur due to relative deformations and variations in the mounting portions of each laser displacement meter, and the strain measurement device is large because only a plurality of laser displacement meters are combined individually. Therefore, it becomes difficult to realize a small measuring device or a so-called handy type strain measuring device.

  In addition, in a strain measuring device that is simply a combination of a plurality of laser displacement meters, information on a portion that is not directly related to strain (that is, a region other than the target portion where strain is to be measured) is necessarily included in the measured value. As a result, there is a disadvantage that the distortion detection accuracy is lowered.

JP 2003-194508 A Japanese Patent Laid-Open No. 11-014445 JP 2001-41717 A JP-A-7-4928 JP-A-9-297010 JP 2001-124516 A

  The present invention relates to the above-described problems in the conventional optical vibration distortion measuring apparatus using laser light, particularly the apparatus based on detection of the movement amount of the spectral pattern. Although it can cope with measurement of vibration distortion mainly composed of bending deformation, it is difficult to cope with measurement of vibration distortion mainly composed of torsional deformation generated in the piping system. In the case where the measurement target portion is planar like the outer surface of the pipe, when the pipe vibrates in the direction orthogonal to the measurement direction, the distortion measurement error increases due to the influence of the curved reflection of the laser beam. An apparatus in which a plurality of laser displacement gauges are simply arranged side by side is inevitable to generate measurement errors due to relative deformation and variation of the mounting portions of the laser displacement gauges. The strain measuring device cannot be downsized and handheld, e. The measurement value includes information on the region other than the target region where the strain is to be measured, and it is difficult to improve the strain detection accuracy. By using at least 6 laser displacement meters mounted in a step shape, it is possible to measure both vibrational strains, mainly bending deformation and torsional deformation, and easily apply to high temperature and high radiant heat measurement objects. It is a main object of the present invention to provide an optical vibration distortion measuring apparatus that can perform high-precision distortion measurement with less noise on a target portion, and that can be downsized and handheld. Is.

  In order to solve the above-mentioned problems, the invention relating to the vibration strain measuring apparatus of claim 1 of the present application is characterized in that at least a measurement target portion that vibrates using at least six laser displacement meters attached in a two-stage manner to one folder. The displacement is measured at six locations, and the distortion due to the vibration deformation mainly consisting of bending deformation and torsion deformation generated in the measurement object is calculated from the difference in displacement measured by each laser displacement meter. Is a basic configuration of the invention.

  The invention of claim 2 of the present application is the invention of claim 1, wherein a common light source is used as the light source of the plurality of laser displacement meters.

  The invention according to claim 3 of the present application relates to at least three first laser light reflectors arranged at predetermined intervals in the central axis direction on the outer surface of a vibrating beam-like measurement object, and the first At least three second laser light reflecting plates arranged symmetrically with respect to one reflecting plate and the central axis, a laser beam incident on each first laser light reflecting plate and each second laser light reflecting plate and each reflection At least six laser displacement meters that individually receive the reflected laser beams from the plate, a folder in which the laser displacement meters are arranged and fixed in two stages, and each reflection measured by each laser displacement meter The basic configuration of the present invention includes a calculation device that calculates distortion including torsional distortion and bending distortion due to vibrational deformation of a target portion of the object to be measured using the vibration displacement of the detection point on the plate.

  A fourth aspect of the present invention is the short cylinder according to the third aspect, wherein the object to be measured is a pipe, and the first laser light reflecting plate and the second laser light reflecting plate are detachably attached to the outer peripheral surface of the pipe. A flat fin body projecting outward at an angular pitch of 180 ° on the outer surface of the body is used.

  The invention of claim 5 of the present application is the invention of claim 3, wherein at least six laser displacement meters are formed from two common light emitting portions arranged in two stages and at least six light receiving portions of the laser displacement meters. And it is set as the structure which injects a laser beam into each detection point from the said common light emission part.

  In the present invention, since a plurality of laser displacement meters attached to one common folder is used, there is no error due to relative deformation or variation of the attachment parts of each displacement meter, and high-precision distortion is achieved. In addition, the mounting of the laser displacement meter does not require a rigid mounting equipment, and the strain measuring device can be highly accurate, downsized and / or handheld.

  Further, in the present invention, using at least six laser displacement meters arranged in two stages, distortion is detected from displacements at six positions above and below at least three positions determined at intervals in the axial direction of the measurement object. Since it is designed to measure vibration distortion including both torsional distortion and bending distortion due to vibration deformation, and to directly measure the deformation of the part where distortion is to be measured, distortion It is possible to obtain the distortion of the measurement target region using only the data relating to the information directly related to the information, and as a result, the distortion measurement accuracy can be greatly improved.

  Further, according to the second and fifth aspects of the present invention, since the single light emitting portion is shared as the light source of a plurality of displacement meters, the optical vibration strain measuring device can be downsized and manufactured. The cost can be drastically reduced, and the operability of the measuring instrument itself can be improved, so that a device with excellent operability that facilitates so-called strain measurement can be obtained.

  In addition, in the invention of claim 4 of the present invention, the first laser reflection plate and the second laser reflection plate can be accurately and easily attached and fixed to a desired portion of the pipe as the measurement object, The work efficiency of strain measurement can be greatly increased.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[Embodiment 1]
FIG. 1 is an explanatory view showing the overall configuration of an optical vibration distortion measuring apparatus A according to the present invention, FIG. 2 is a perspective view of a laser beam reflector mounting fixture C used in the present invention, and FIG. 3 is a laser beam. 4 is a cross-sectional view of the reflector fixture C, FIG. 4 is a perspective view showing an embodiment of strain measurement using the optical vibration strain measuring apparatus A according to the first embodiment, and FIG. It is explanatory drawing of the symbol used with the calculating formula which calculates | requires distortion from displacement.

1 to 4, A is an optical vibration distortion measuring device, B is a vibration displacement detector, C is a laser light reflector mounting fixture, S is a pipe support fixing point, P _{1a to} P _3b are detection points, 1 is a pipe which is an object to be measured, 2 is a laser displacement meter, 3 is a folder for supporting and fixing the laser displacement meter, 4a is a power supply device, 4b is an AD converter, 5 is an arithmetic device, 6a is an incident laser beam, and 6b is A reflected laser beam, 7 is a cable, 8 is a short cylindrical body, 8a is a projection, 9a is a first laser light reflecting plate, 9b is a second laser light reflecting plate, and 10a and 10b are spare laser light reflecting plates.

The pipe 1 which is the measurement object is supported in a so-called cantilever shape as shown in FIG. 1, and its tip portion reciprocates in the direction of arrow II '. In this embodiment, a position P ₁ that is about 10 mm away from one support point of the stainless steel pipe having an outer diameter of 34 mm and an inner diameter of 27.2 mm is set as the first detection point.

  For the laser displacement meter 2, a known LK-G80 type laser displacement meter (sampling period 20 μs, resolution 0.2 μm) manufactured by Keyence Corporation is used. Of course, the laser displacement meter may be of any type. Further, since the laser displacement meter itself is known, its detailed description is omitted here.

  In this embodiment, six laser displacement meters having the same specifications are arranged in two stages, but the measurement accuracy is improved by using six or more laser displacement meters. Of course, it is also good.

  The folder 3 is formed from a flat plate-shaped steel plate into a square frame, and an appropriate fixing bracket (not shown) is provided at a lower portion thereof. The material of the folder 3 may be a hard synthetic resin board, is lightweight, can securely support and fix the laser displacement meter 2, and does not cause deformation by the support and fixation of the laser displacement meter. Any material and form may be used. Further, the vibration displacement detector B of the optical vibration strain measuring apparatus A according to the present invention is formed from the folder 3 and six laser displacement meters 2 mounted and fixed thereon.

  The power supply device 4a and the AD conversion device 4b are provided separately from the folder 3, and the displacement measurement signal input from the laser displacement meter 2 via the cable 7 is converted into a digital signal by the AD conversion device 4b. And input to the arithmetic unit 5.

  A personal computer is used for the arithmetic device 5, and the amplitude of strain (bending strain and torsional strain) that vibrates based on arithmetic expressions (1) to (12) to be described later and the vibration deformation of the measurement object 1. The curvature radius R at the time is calculated.

  As shown in FIGS. 2 and 3, the laser light reflector mounting fixture C includes a short cylindrical body 8 to be mounted on the outer peripheral surface of the pipe 1, and a flat reflector that projects vertically outward from the outer surface thereof. 9a, 9b, 10a, 10b and a ring-shaped protrusion 8a having a square cross section fixed to the inner peripheral surface of the short cylindrical body 8 and the like, and each of the four reflecting plates 9a, 9b, 10a, 10b. Are fixedly attached to the short cylindrical body 8 at an angular pitch of 90 °.

The laser light reflector mounting fixture C has a structure that is attached and fixed to an arbitrary measurement target portion of the pipe 1 by using the elastic force of the short cylindrical body 8, and includes three pieces at predetermined intervals. A laser beam reflector mounting fixture C is fixed to the pipe 1.
That is, the three fixtures C attached to the pipe 1 are aligned so that the first laser light reflecting plate 9a and the second laser light reflecting plate 9b are in a line in the axial direction of the pipe 1, respectively. As a result, the first laser light reflecting plate 9a and the second laser light reflecting 9b are attached and fixed in an axially symmetrical manner.

  In the present embodiment, the laser light reflector mounting fixture C is mounted and fixed to the pipe 1 by utilizing the elastic force of the short cylindrical body 8. The ends may be connected and fixed to each other using bolts, nuts, or the like.

  In the present embodiment, in consideration of the case where the laser beam 6a is incident from above or below, in addition to the first laser light reflection plate 9a and the second laser light reflection plate 9b, the reflection plates 10a and 10b are short. Although provided in the cylindrical body 8, when the vibration direction of the pipe 1 is fixed, the reflectors 10a and 10b may be omitted.

  In the present embodiment, the three laser light reflector mounting fixtures C are individually provided at the site to be inspected, but the short cylindrical body 8 is long and the three laser light reflectors are provided. The fixture C may be integrated, and the first laser light reflecting plate and the third laser light reflecting plate may be fixed to the single short cylindrical body 8 in a row at predetermined intervals.

  Further, a projection body 8a having a square cross section is fixed to the inner peripheral surface of the short cylindrical body 8 of the laser beam reflector mounting fixture C. By providing the projection body 8a, the laser beam reflector mounting fixture C is provided. The mounting position can be more accurately regulated.

Next, a method for measuring vibration distortion and the like by the optical vibration distortion measuring apparatus according to the present invention will be described.
First, three laser light reflector mounting fixtures C are attached to a target portion of the inspection object (pipe 1) at a predetermined interval, and each first laser light reflector 9a and each second laser light reflector 9b. Adjust the interval and alignment state.
Next, the vibration displacement detector B of the optical vibration distortion apparatus A is disposed so as to face the laser light reflecting plates 9a and 9b. Since the vibration displacement detector B of the optical vibration strain measuring apparatus A according to the present invention is configured to be portable, the outer surface of the laser displacement meter 2 and the measurement object 1 can be adjusted by adjusting the installation position of the folder 3. Is set to about 8 cm, and then the folder 3 is fixed on a stationary table (not shown).
In the optical vibration distortion measuring apparatus of the embodiment shown in FIG. 1, vibration displacement (sampling period 20 μs) with a resolution of about 0.2 μm can be measured.

Thereafter, each laser displacement meter 2 is operated, and as shown in FIGS. 4 and 5, using the respective incident light 6a and reflected light 6b, six detection points (that is, three first laser light reflecting plates 9a). And three second laser light reflectors) P _{1a to} P _3b are measured for vibration displacement amounts, ie, vibration displacement amplitudes u ₁₁ , u ₁₂ , u ₁₃ , μ ₂₁ , u ₂₂ , u ₂₃ .
In FIG. 5, D is the diameter or thickness of the measurement object (pipe) 1, R is the radius of curvature of the shape of the measurement object 1 deformed by vibration, u ₁₁ , u ₁₂ , u ₁₃ , u ₂₁ , u ₂₂ and u ₂₃ are amplitudes of vibration displacements of the detection points P _{1a to} P _3b measured by the laser displacement meters 2, X ₁ and X ₂ are intervals of the laser displacement meters 2, and h is a height direction of the laser displacement meters 2. , Θ is a twist angle, G is a transverse elastic modulus, ε is an amplitude of bending strain, γ is an amplitude of torsional strain, and τ is stress.

The displacements measured by the laser displacement meters 2, that is, the amplitudes u ₁₁ , u ₁₂ , u ₁₃ , u ₂₁ , u ₂₂ , u ₂₃ of the vibration displacements are sent to the arithmetic unit 5 via the cable 7 and the AD converter 4b. Here, based on the following equations (1) to (12), the amplitude ε of the vibration strain (bending strain), the amplitude γ of the vibration strain (torsional strain), and the radius of curvature of the vibration deformation shape of the measurement object 1 R and the like are calculated.
In addition, the said (1)-(4) type | formula is disclosed by the mechanical engineering handbook etc., and is a well-known thing as an arithmetic expression.

The object to be measured is the stainless steel tube 1 (outer diameter D = 34 mm, inner diameter φ = 27.2 mm, position P ₁ approximately 10 mm away from the support fixing point S (of the first laser light reflecting plate 9a and the second laser light reflecting plate 9b). The optical vibration displacement measuring device shown in FIG. 4 was set with each center point P _1a · P _1b ) as the first detection point and the distance between the outer surface of the stainless steel tube 1 and the laser displacement meter 2 being 36 mm.

The installation interval of the laser displacement meter 2 at this time is X ₁ = 36 mm and X ₂ = 72 mm, and the amplitudes of the vibration displacement measured by the laser displacement meter 2 are u ₁₁ = 0.0034 mm, u ₁₂ = They were 0.0271 mm, u ₁₃ = 0.0384 mm, u ₂₁ = 0.0010 mm, u ₂₂ = 0.029 mm, and u ₂₃ = 0.0318 mm.

Further, the curvature radius R of the vibration deformation shape calculated for the measurement target part at this time was R = 102047 mm, and the bending strain width ε was ε = 167 μstrain. When the longitudinal elastic modulus E of the pipe 1 is E = 200000 N / mm ² , this strain is the strain when the stress σ is σ = 32.5 N / mm ² , and the lateral elastic modulus G is G = 7690 N / mm ^2. Then, it corresponds to the strain when the stress τ is τ = 1.14 N / mm ² .
[Embodiment 2]

  FIG. 6 is an inclined surface showing an outline of the optical vibration distortion measuring apparatus A according to the second embodiment of the present invention. In FIG. 6, 11 is a laser displacement meter light emitting unit, and 12 is a laser displacement meter light receiving unit. is there.

That is, in the second embodiment, the light emitting unit 11 of the laser displacement meter is formed in a common light emitting unit, and laser is simultaneously transmitted from one common light emitting unit 11 to each detection point P _1a , P _2a , P _3a . While the beam 6a is incident, the reflected laser beam 6b from each of the detection points P _1a , P _2a , P _3a is configured to be incident on the light receiving unit 12 of each laser displacement meter.
In FIG. 6, 3 is a folder, 6a is an incident laser beam, and 6b is a reflected laser beam. The operation as the optical vibration distortion measuring apparatus A and the distortion measurement method using the same are described in FIGS. This is the same as the case of the first embodiment shown in FIG.

  The present invention can be applied to measurement of vibration distortion of a beam-like vibrating structure in any plant equipment such as a power plant and equipment / devices such as automobiles.

It is explanatory drawing which shows the whole structure of the optical vibration distortion measuring device which concerns on this invention. It is a perspective view of the laser beam reflector mounting fixture C used in the present invention. It is sectional drawing of the laser beam reflector mounting tool B. It is a slope figure showing an embodiment of distortion measurement using an optical vibration distortion measuring device concerning a 1st embodiment of the present invention. FIG. 3 is an explanatory diagram of each symbol used in an arithmetic expression for obtaining a strain from a displacement in the strain measurement of FIG. 2. It is a perspective view which shows the outline | summary of the optical vibration distortion measuring device which concerns on 2nd Embodiment of this invention.

Explanation of symbols

A is the optical vibration displacement measuring device B the vibration displacement detector C is laser light reflective plate fixture S support fixing portion P _1a to P _3b detection points (a total of 6 locations)
D is the diameter (or thickness) of the measuring object 1
R is the radius of curvature of the deformed shape
u _{11 to} u ₂₃ are vibration displacement amplitudes X ₁ and X ₂ measured with a laser displacement meter, laser displacement meter mounting interval ε is bending strain amplitude γ and twist strain amplitude 1 is an object to be measured (pipe)
2 is a laser displacement meter 3, a folder 4 a, a power supply 4 b, an AD converter 5, an arithmetic unit 6 a, an incident laser beam 6 b, a reflected laser beam 7, a cable 8, a short cylinder 8 a, and a projection 9 a reflecting the first laser beam. The plate 9b is the second laser beam reflecting plate 10a, the laser beam reflecting plate 10b, and the laser beam reflecting plate 11 is a common light emitting unit (common light source).
12 is a laser displacement meter light receiving unit

Claims (5)

  Measure the displacement of at least six locations of the measurement target that vibrate using at least six laser displacement meters mounted in two stages in one folder, and use the difference in displacement measured by each laser displacement meter to determine the measurement target. An optical vibration distortion measuring apparatus characterized in that a distortion due to vibration deformation mainly consisting of generated bending deformation and torsion deformation is calculated by an arithmetic device.   The optical vibration distortion measuring apparatus according to claim 1, wherein a common light source is used as a light source of the plurality of laser displacement meters.   At least three first laser light reflectors arranged at predetermined intervals in the central axis direction on the outer surface of the vibrating beam-like measurement object, and the first reflector and the symmetrical arrangement with respect to the central axis At least six second laser light reflecting plates and at least six laser beams incident on the first laser light reflecting plates and the second laser light reflecting plates and individually receiving the reflected laser beams from the reflecting plates. Measurement symmetry using a basic laser displacement meter, a folder in which each laser displacement meter is arranged and fixed in two stages, and a vibration displacement of a detection point on each reflector measured by each laser displacement meter An optical vibration distortion measuring device comprising an arithmetic device for calculating distortion including torsional distortion and bending distortion caused by vibration deformation of a target part of an object.   The object to be measured is a pipe, and the first laser light reflection plate and the second laser light reflection plate are moved outward at an angular pitch of 180 ° on the outer surface of a short cylindrical body that is detachable from the outer peripheral surface of the pipe. The optical vibration distortion measuring device according to claim 3, wherein the fin is a flat fin projecting toward the surface.   At least six laser displacement meters are formed from two common light emitting portions arranged in two stages and at least six light receiving portions of the laser displacement meters, and the first light emitting plate and the first laser light reflecting plate are formed from the common light emitting portions. The optical vibration distortion measuring apparatus according to claim 3, wherein laser light is incident on each detection point on the two laser light reflecting plate.

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