JP2015172496A - In-pipe traveling ultrasonic inspection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an in-pipe traveling ultrasonic inspection device which can perform an inspection such as a thickness reduction inspection on a pipe wall from an inner peripheral surface of a pipe by using an ultrasonic wave while traveling in the pipe.SOLUTION: An in-pipe traveling ultrasonic inspection device comprises: a base 2 which is provided in a connection member 72 connected to a traveling carriage unit 6 traveling on an inner peripheral surface of a pipe using a plurality of drive wheels 5; a guide part 4 which is supported on the base, displaceable in a radial direction of the pipe and energized so as to always contact the inner peripheral surface of the pipe; and a transmission probe 1A and a reception probe 1B which are supported on the base 2 so as to interlock with the radial displacement of the guide part 4. The transmission probe 1A has an interval where the ultrasonic wave incident on the inner peripheral surface propagates through a space with the inner peripheral surface, and the reception probe 1B has an interval where the ultrasonic wave output from the inner peripheral surface propagates through a space with the inner peripheral surface.

Description

  The present invention relates to an in-pipe ultrasonic inspection apparatus that inspects a pipe wall from the inner peripheral surface of a pipe using ultrasonic waves while running in a pipe such as an embedded pipe.

  In buried piping, it is important for maintenance to measure the corrosion thinning of the outer surface, but in order to inspect the thinning directly from the outer surface, it is necessary to dig the ground to expose the piping, which is expensive. In order to avoid such pipe exposure work, it has been proposed to inspect corrosion thinning from the inner peripheral surface of the pipe using an inspection apparatus that moves in the pipe. For example, Patent Document 1 discloses an inspection apparatus that inspects a thinned portion of a pipe by inserting a moving body attached with a magnetic sensor into a magnetically saturated pipe and detecting leakage magnetic flux by the magnetic sensor. . The leakage magnetic flux method for detecting the presence or absence of thinning by detecting such leakage magnetic flux is disadvantageous because it requires a permanent magnet or a large electromagnet to magnetize the tube.

  As an inspection method other than the leakage magnetic flux method, an ultrasonic inspection method for inspecting a thinned portion by measuring the propagation time until the reflected wave of the ultrasonic wave incident on the tube wall returns is well known. Patent Document 2 discloses a self-propelled inspection apparatus in which an ultrasonic inspection method is applied to a carriage traveling in a pipe. However, when the inside of the tube is not filled with a liquid such as water, in order for the ultrasonic wave transmitted from the ultrasound probe to be efficiently incident on the inner peripheral surface of the tube, the inside of the ultrasound probe and the tube A contact medium (coupling agent) such as water or oil is necessary between the peripheral surface. However, in order to perform inspection by supplying a contact medium to the gap between the ultrasonic probe and the inner peripheral surface of the pipe while moving in the pipe, and then removing the supplied contact medium, a large-scale apparatus is required. Required and costly. If such a thickness inspection is performed without a contact medium, the energy of the reflected wave (surface reflected wave) reflected from the inner peripheral surface of the tube is too large due to the difference in acoustic impedance between air and the tube. The surface reflected wave necessary for the thinning inspection overlaps with the reflected wave from the bottom of the tube wall (bottom reflected wave), and the measurement becomes almost impossible.

JP 2003-270210 A JP 2003-302217 A

  In view of the above situation, there is a demand for an in-pipe ultrasonic inspection apparatus capable of performing inspections such as thinning of a pipe wall from the inner peripheral surface side of the pipe using ultrasonic waves while running in the pipe.

An in-pipe traveling ultrasonic inspection apparatus according to the present invention for inspecting a pipe while running inside the pipe is as follows.
A traveling cart unit that travels on the inner peripheral surface of the tube using a plurality of drive wheels, a coupling member that is coupled to the traveling cart unit and extends in the tube axis direction of the tube, and a base provided on the coupling member The base is supported by the base so as to be symmetric with respect to the axis of the tube, and is urged so that it can be displaced in the radial direction of the tube and is always in contact with the inner peripheral surface of the tube. A guide part, a transmission probe holding part supported by the base so as to be interlocked with a radial displacement of the guide part, and a base supported so as to be interlocked with a radial displacement of the guide part. A transmission probe fixed to the transmission probe holding unit so that a space between the reception probe holding unit and the ultrasonic wave incident on the inner peripheral surface can be spatially propagated. And an interval in which the ultrasonic wave coming out from the inner peripheral surface propagates in space with the inner peripheral surface And a receiving probe is fixed to the receiving probe holder as kicking. The term “space” used in the present invention means an air space mainly filled with air or a gas space filled with gas (such as city gas).

  According to this configuration, when an ultrasonic inspection such as thinning of the tube wall is performed from the inner peripheral surface, the space between the ultrasonic probe (transmitting probe and receiving probe) and the inner peripheral surface of the tube is reduced. Since the ultrasonic wave is propagated in space without any coupling agent, not only the pre-treatment and post-treatment of the coupling agent become unnecessary, but also the ultrasonic probe moves inside the tube during traveling inside the tube. The inconvenience of being caught on the surface can be avoided. In addition, a so-called tandem transmission method (single-sided oblique transmission method) is adopted, in which a transmitting probe that makes ultrasonic waves incident on the tube wall and a receiving probe that receives the ultrasonic waves emitted from the tube wall are separate bodies. Therefore, it is possible to avoid the adverse effect of the surface reflected wave from the inner peripheral surface of the tube on the received wave to be evaluated. In addition, the transmission probe and the reception probe can change the posture (distance and angle) of the transmission probe and the reception probe with respect to the inner peripheral surface of the tube wall in the radial direction of the tube. It is fixed to the probe holding part (transmitting probe holding part and receiving probe holding part) linked to the guide part that follows the inner peripheral surface by being urged so as to always contact the inner peripheral surface. ing. As a result, fluctuations in posture (distance and angle) relative to the inner peripheral surface of the tube wall in the transmission probe and reception probe during traveling in the tube due to distortion of the tube to be inspected should be substantially avoided. Can do. In particular, a transmission probe and a reception probe between a front traveling carriage and a rear traveling carriage in a traveling carriage unit composed of a front running carriage and a rear running carriage as one of the objects of the present invention. When the is placed, the positions of the transmission probe and the reception probe with respect to the inner peripheral surface of the tube are fluctuated during traveling, and the accuracy of ultrasonic measurement is deteriorated. Such positional fluctuations of the transmitting probe and the receiving probe during traveling with respect to the inner peripheral surface of the tube can be avoided by the guide portion biased so as to always contact the inner peripheral surface of the tube. In particular, in the single-sided oblique transmission method, the change in the posture of the transmission probe and the reception probe with respect to the inner peripheral surface of the tube wall has a great adverse effect on the inspection result, so the configuration of the guide portion is important.

  In one of the preferred embodiments of the present invention relating to the radial displacement structure necessary for causing the guide portion to follow the inner peripheral surface of the pipe, the base extends from the connecting member to both sides in the pipe radial direction. The movable base is supported on both sides of the base and the arm base so as to be displaceable in the radial direction, and the guide is provided on the movable base. The arm base that constitutes the base provided on the connecting member connected to the traveling unit is inevitably displaced with respect to the inner peripheral surface of the pipe during traveling, but the radial direction relative to the arm base The displaceable movable base can be displaced with respect to the arm base so as to maintain the posture with respect to the inner peripheral surface of the pipe in accordance with the movement of the guide portion.

  The inner diameter of the pipe used for the buried gas pipe or the like is about 200 mm to 1 m, and the moving ultrasonic inspection apparatus in the pipe must be configured as compact as possible. In one preferred embodiment for realizing such a compact structure, the arm base includes a first arm portion and a second arm portion spaced apart in the tube axis direction, and the first arm The transmission probe holding part is provided on a movable base supported by the first part, and the reception probe holding part is provided on the movable base supported by the second arm part. In this configuration, the transmission probe holding unit and the reception probe holding unit are supported by the base material via separate movable bases and arm parts, respectively, so the structure of each arm part and each movable base Is compact because it only needs to support one probe holding part for fixing one probe. Moreover, since the load burden applied to each arm part and each movable base is small, it is possible to easily suppress bending and vibration during traveling.

  The ultrasonic wave that directly propagates from the transmitting probe or reflects off the inner peripheral surface of the tube wall and enters the receiving probe becomes a noise signal at the time of inspection. In order to cut off the ultrasonic waves that enter the receiving probe from the transmitting probe only by spatial propagation without propagating in the tube wall, in one preferred embodiment of the present invention, the transmitting probe is used. A sound wave shield that blocks ultrasonic waves that come out of the transmission probe and travel toward the reception probe by spatial propagation is supported between the base and the reception probe. At this time, if a slight gap is formed between the tip of the sound wave shield and the inner peripheral surface so that contact between the sound wave shield and the inner peripheral surface of the pipe does not occur during travel, stable travel can be achieved. Sex is obtained. Furthermore, the fact that the sonic shield is not in contact with the inner peripheral surface of the tube means that the condition of the peripheral surface of the inner peripheral surface of the tube wall where the ultrasonic wave propagates is maintained in a constant state, so that stable super Contributes to sonography.

  In order to move the ultrasonic probe in the tube as stably as possible, the stability of the base during travel is also important. For this reason, in one preferred embodiment of the present invention, the traveling carriage unit includes a front traveling carriage and a rear traveling carriage connected by the connecting member, and the base includes the front traveling carriage and the rear side carriage. It is arranged between the traveling carriage. Since the base is provided on the connecting member that connects the traveling carts arranged in the longitudinal direction in the tube axis direction, the stability of the base during traveling is ensured, and the ultrasound probe is also stable as a result. Is obtained.

  In one preferred embodiment of the present invention, in order to realize a stable traveling of the traveling cart unit itself in the pipe, the driving wheel is spaced from the connecting member in the circumferential direction of the tube. It is attached to the ends of a plurality of support arms extending radially in the radial direction. With this configuration, the driving wheel can be stretched in the radial direction of the pipe via the support arm, so that traveling stability can be obtained. Further, since the driving wheels are provided on the plurality of radially extending support arms, it is possible to spirally travel in the pipe, thereby enabling a substantially full inspection of the inner peripheral surface of the pipe. .

It is a schematic diagram explaining the basic composition of the ultrasonic inspection unit by this invention. It is a perspective view of the in-pipe running ultrasonic inspection apparatus which is one of the specific embodiments of the present invention. It is a top view of an ultrasonic inspection unit. It is a side view of an ultrasonic inspection unit. It is a schematic diagram explaining the ultrasonic oblique angle transmission method employ | adopted by this invention. FIG. 2 is a perspective view of an in-pipe traveling carriage according to FIG. It is a front view of an in-pipe travel cart. It is a disassembled perspective view of a spherical drive wheel. It is a C scan figure which shows the experimental result with respect to the artificial hole provided in the pipe wall.

Before describing a specific embodiment of the in-pipe traveling ultrasonic inspection apparatus according to the present invention, a basic configuration characterizing the present invention will be described with reference to FIG.
This in-pipe traveling ultrasonic inspection apparatus includes a traveling carriage unit 6 traveling in a pipe, an ultrasonic inspection unit 1 attached to the traveling carriage unit 6, and an inspection sent from the ultrasonic inspection unit 1 via a communication cable. Based on the result, an inspection evaluation unit 100 for detecting a thinned portion in the pipe is provided.

  The traveling cart unit 6 illustrated in FIG. 1 is arranged at an interval in the tube axis direction and is connected by a connecting member 72 extending along the tube axis, and the front traveling cart 6A and the rear traveling cart 6B. It consists of. The structures of the front traveling carriage 6A and the rear traveling carriage 6B are substantially the same. The front traveling carriage 6A and the rear traveling carriage 6B include a carriage main body 10, an arm unit 8 extending radially from the carriage main body 10 in a pipe radial direction, and a drive wheel 5 provided at a tip portion of the arm. . As can be understood from FIG. 1, the driving wheel 5 is pressed against the inner peripheral surface of the pipe by an urging mechanism not shown here, and the central axis of the carriage body 10 is positioned substantially at the pipe axis. The arm unit 8 and the drive wheel 5 are supported by a tensioning action on the inner peripheral surface of the pipe.

  The ultrasonic inspection unit 1 illustrated in FIG. 1 is supported by the connecting member 72 between the front traveling cart 6A and the rear traveling cart 6B. In the ultrasonic inspection unit 1, the base 2 fixed to the connecting member 72, the guide unit 4 urged so as to always contact the inner peripheral surface of the tube, and the transmission probe 1A in a predetermined posture. A transmission probe holding unit 11 that is fixed and a reception probe holding unit 12 that fixes the reception probe 1B in a predetermined posture are provided.

  The base 2 includes an arm base 20 extending on both sides in the radial direction and a movable base 30 supported on both sides of the arm base so as to be capable of radial displacement. Here, the arm base 20 includes a base bracket 23 and a first arm portion 21 and a second arm portion 22 that extend in a fork shape from the base bracket 23 toward the inner peripheral surface of the pipe on both sides in the pipe radial direction. In other words, a base bracket 23 is formed in an intermediate region between the first arm portion 21 and the second arm portion 22 extending in the tube diameter direction. A movable table 30 is provided in each end region of the first arm portion 21 and the second arm portion 22 so as to be radially displaceable. Since each movable table 30 is biased toward the inner peripheral surface by a biasing mechanism (not shown), each movable table 30 includes a contact body of the guide unit 4 so as to contact the inner peripheral surface of the pipe. A guide part 4 is provided. Furthermore, each movable platform 30 of the first arm unit 21 is provided with a transmission probe holding unit 11, and each movable platform 30 of the second arm unit 22 is provided with a reception probe holding unit 12. . In the transmission probe holding unit 11 and the reception probe holding unit 12 or the transmission probe 1A and the reception probe 1B, ultrasonic waves excited by the transmission probe 1A propagate in space and enter the inner peripheral surface. Then, it is positioned so as to propagate along the tube wall in the tube axis direction, exit again from the inner peripheral surface, and reach the receiving probe 1B via space propagation. Note that the positional relationship between the transmission probe holding unit 11 and the reception probe holding unit 12, that is, the positional relationship between the transmission probe 1A and the reception probe 1B is determined by the ultrasonic wave from the transmission probe 1A. It may be configured to propagate in the circumferential direction of the tube wall and reach the reception probe 1B.

  Since the guide section 4 and the transmission probe 1A or the reception probe 1B used in pairs are fixed to the same movable table 30, they are linked with the radial displacement of the guide section 4. That is, even if the tube is deformed and the inner peripheral surface is distorted, the distance between the transmission probe 1A and the reception probe 1B and the inner peripheral surface is substantially reduced by the guide portion 4 following the inner surface. Can be kept constant.

  Between the transmission probe 1A and the reception probe 1B, a sound wave shield 28 that blocks the ultrasonic wave that exits from the transmission probe 1A and travels toward the reception probe 1B by spatial propagation is provided between the arm base 20 and the transmission probe 1A. The base bracket 23 is configured to extend in the radial direction. A gap is formed between the tip of the sound wave shield 28 and the inner peripheral surface so as not to obstruct the running.

  Next, one specific embodiment of the in-pipe traveling ultrasonic inspection apparatus according to the present invention will be described with reference to the drawings. This in-pipe traveling ultrasonic inspection apparatus also has the basic structure described with reference to FIG. FIG. 2 is a perspective view of the in-pipe travel assembly of the in-pipe travel ultrasonic inspection apparatus. This in-pipe travel assembly is composed of a travel cart unit 6 and an ultrasonic inspection unit 1 that are self-propelled in the pipe. The traveling cart unit 6 includes a front traveling cart 6A that travels at the front and a rear traveling cart 6B that travels at the rear, and is connected to each other by a rod-shaped connecting member 72. The ultrasonic inspection unit 1 is supported by the connecting member 72 at an intermediate portion between the front traveling carriage 6A and the rear traveling carriage 6B. The front traveling trolley 6A and the rear traveling trolley 6B travel in the pipe by the drive wheels 5 provided at the tip of the arm unit 8 extending radially from the trolley body 7 rolling on the inner peripheral surface of the pipe. During straight running, the carriage main body 7 and the connecting member 72 connected to the carriage main body 7 are located substantially at the center of the tube axis.

  In this in-pipe traveling ultrasonic inspection apparatus, in order to inspect the thinning state of the tube wall while traveling in the tube by the single-sided oblique transmission method (tandem transmission method) using the transmission probe 1A and the reception probe 1B, As shown in FIGS. 2, 3, and 4, the ultrasonic inspection unit 1 supports two sets of the transmission probe 1 </ b> A and the reception probe 1 </ b> B that are opposed to the tube axis. The base 2 is configured as an arm base 20 extending in a bifurcated shape from the tube axis to both sides in the tube radial direction. The arm base 20 includes a base bracket 23 fixed to the connecting member 72, and a first arm portion 21 and a second arm portion 22 that extend linearly from the base bracket 23 to both sides in the pipe radial direction. Furthermore, movable tables 30 are attached to both ends of the first arm portion 21 and the second arm portion 22 so as to be displaceable in the tube diameter direction by the slide mechanism 24.

  As can be understood from FIGS. 3 and 4, the slide mechanism 24 includes a rail 241 provided on the lower surfaces of the first arm portion 21 and the second arm portion 22, and a slide body 242 provided on the upper surface of the movable base 30. In addition, the movable base 30 moves in the pipe radial direction by sliding the sliding body 242 engaged with the rail 241. Furthermore, spring plungers 243 are provided on the first arm portion 21 and the second arm portion 22 so as to contact both side surfaces of the movable base 30 in the tube radial direction. That is, since the movable table 30 is pushed and pulled by the spring plungers 243 arranged on both sides in the sliding direction, when a force (displacement) in the tube diameter direction is applied to the movable table 30, The movable base 30 can be displaced with respect to the base bracket 23 in the stroke range. In addition, the relationship of the urging | biasing force of both spring plungers 243 is always set so that the movable stand 30 may face the inner peripheral surface of a pipe | tube. Further, since the spring plunger 243 is attached so that the position in the tube diameter direction is set by screwing adjustment, the spring plunger 243 is set at an arbitrary position within a predetermined adjustment range.

  Further, the movable table 30 includes a case body 31 and a revolving body 32. The sliding body 242 of the sliding mechanism 24 is fixed to the upper surface of the case body 31, and the revolving body 32 revolves around a revolving axis P1 extending perpendicularly to the upper surface. On the distal end side (the side facing the inner peripheral surface of the tube) of the swivel body 32, the guide unit 4 and the transmission probe holding unit 11 or the reception probe holding unit 12 are provided. The transmission probe holding unit 11 is provided on the revolving body 32 supported by the first arm unit 21, and the reception probe holding unit 12 is provided on the revolving body 32 supported by the second arm unit 22. ing. The pair of transmission probe 1A and transmission probe holding unit 11 used in the single-sided oblique transmission method needs to be accurately inclined with respect to the inner peripheral surface of the tube. For this reason, the swivel body 32 is formed with a protrusion 33 protruding in the radial direction of the swivel axis P1, and the case body 31 is provided with an adjustment screw 34 for contacting the protrusion 33 and turning the swivel body 32. Provided on both sides of the protrusion 33. By the fine turning of the turning body 32 by the adjusting screw 34, the transmission probe 1A and the reception probe 1B are set to desired inclination angles with respect to the inner peripheral surface of the tube.

  In this embodiment, the guide portion 4 is formed as a ball holding body 42 that holds the rotating ball 41 so as to be exposed toward the inner peripheral surface of the tube. Since this ball holding body 42 is supported and fixed to the movable base 30 attached to the arm base 20, the arm base comes into contact with the rotating ball 41 arranged symmetrically with respect to the central axis P0. No. 20 holds the stretched state against the inner peripheral surface of the pipe. More specifically, the base bracket 23 is supported by the rotating ball 41 from the first arm portion 21 through the case body 31, the swiveling body 32, and the ball holding body 42, and is supported by being stretched against the inner peripheral surface of the pipe. The first arm portion 21 is supported by the rotating ball 41 so as to be stretched and supported by the rotating ball 41 through the case body 31, the revolving body 32, and the ball holding body 42. As a result, the base bracket 23 is stretched and supported before and after the tube axis direction, and as a result, traveling stability of the ultrasonic inspection unit 1 is ensured.

  The transmission probe 1A and the reception probe 1B, which are used as a single-sided oblique transmission method, transmit ultrasonic waves in space, so that the ultrasonic waves emitted from the transmission probe 1A are directly received only by spatial propagation. There is a possibility of entering the probe 1B. In order to avoid this, a thin plate that reaches between the first arm portion 21 and the second arm portion 22 and between the transmitting probe 1A and the receiving probe 1B and reaching the front of the inner peripheral surface of the tube. The sound wave shield 28 is attached to the base bracket 23.

  FIG. 5 schematically shows the ultrasonic inspection method employed in the ultrasonic inspection unit 1. This ultrasonic inspection method is transmitted from the transmission probe 1A, enters the tube wall through space propagation, propagates through the tube wall, exits the tube wall again, and reaches the reception probe 1B through space propagation. The ultrasonic wave is evaluated to detect the state of the wall of the tube, particularly the presence of thinning occurring on the outer peripheral surface of the tube. For example, when a corrosion dent has occurred on the outer peripheral surface of the pipe, the amplitude of the transmitted wave is reduced because the propagation of the ultrasonic wave is obstructed by the corrosion dent, and therefore thinning is determined based on the decrease in the amplitude of the transmitted wave. . At this time, since airborne propagation is used, attention must be paid to the setting of the oblique posture of the transmission probe 1A, that is, the incident angle θi. The relationship between the incident angle and the refraction angle at the ultrasonic tube wall is the speed of sound in the two media that create the boundary, here the gas (gas such as air or city gas) and the tube wall (generally iron, steel, polyester, etc.). This is because, at the boundary between air or gas and a tube wall having a large difference in sound velocity, if the incident angle is different by 1 °, the refraction angle is different in units of 10 °. In addition, since longitudinal waves and transverse waves propagate on the tube wall, for example, in the case of a steel tube having a longitudinal wave sound velocity of about 5920 m / s, the incident angle is inclined for the tandem transmission method (one-side oblique transmission method). Although it is necessary, even if it is slightly tilted, the longitudinal wave is substantially totally reflected, so that it is a transverse wave (a transverse wave sound velocity in the air: about 3240 m / s) that substantially enters the tube wall. Moreover, in the calculation, the longitudinal wave incident angle θi is 6 °, the transverse wave refraction angle θ is 85 °, the longitudinal wave incident angle θi is 7 °, and the transverse wave is totally reflected. However, since the ultrasonic wave is diffused and has a beam width, even if the longitudinal wave incident angle θi is 7 °, the ultrasonic wave component propagates through the tube wall as a transverse wave. Also, the speed of sound of steel pipes varies depending on the product type, and the speed of sound is about half that of steel pipes in synthetic resin pipes such as polyethylene pipes. For this reason, here, the setting condition of the inclination posture of the transmission probe 1A is determined based on the transverse wave refraction angle θ, not the incident angle θi, and the transverse wave refraction that obtains a result by a good oblique transmission method is obtained. The angle θ is basically in the range of 60 degrees or more and less than 90 degrees. Therefore, when the inspection object is a steel pipe, the incident angle θi is about 5 ° to 6 ° in the calculation. However, if the difference in sound speed depending on the steel type and the ultrasonic beam width are taken into consideration, the incident angle θi is about 5 °. ˜7 ° is preferred.

  The ultrasonic inspection of the present invention employs a single-sided oblique transmission method for evaluating transmitted ultrasonic waves emitted from different locations on the same inner peripheral surface as shown in FIG. Therefore, the receiving probe 1B is basically arranged so as to face each other with the same inclination (receiving angle θr) as the inclination (incident angle θi) of the transmitting probe 1A. However, an arrangement (posture) in which the maximum amplitude can be obtained in the calibration work for adjusting the inclination may be employed.

  In the case of ultrasonic flaw detection, it is the selection of an appropriate ultrasonic frequency, which depends on the material and thickness of the tube to be inspected. In the present invention, when the material is steel and the thickness is 5 mm to 7 mm, the rated frequency (center frequency) of the transmission probe 1A and the reception probe 1B is preferably 400 kHz to 700 kHz from experiments and calculations. It has been found. Similarly, from experiment and calculation, the wavelength of the transverse wave propagating through the tube wall of the tube to be inspected is 0.5 to 1.5 times the tube thickness (mm) of the tube to be inspected as the transmission probe 1A. It has also been found appropriate to select a probe having a rated frequency such that

  As shown in FIGS. 2, 6, 7, and 8, the front traveling carriage 6 </ b> A and the rear traveling carriage 6 </ b> B have substantially the same structure. I will explain it. A carriage main body 7 extending in the traveling direction, and a front arm unit 8A and a rear arm unit 8B disposed on the carriage main body 7 with an interval in the traveling direction are provided. Since the front arm unit 8A and the rear arm unit 8B are configured substantially in the same manner, they are simply referred to as the arm unit 8 when it is not necessary to distinguish between them. The arm unit 8 includes three arm modules 80 arranged on the carriage main body 7 so as to be distributed at 120 ° intervals in the circumferential direction of the pipe to be traveled. The arm module 80 is arranged around an oscillation axis Pa extending in a transverse direction (a pipe radial direction that is a cross-sectional direction of the pipe) with respect to a running direction (a pipe axis direction of the pipe) that is the direction of the central axis P0 of the traveling carriage unit 6. It is attached so as to swing and displace (see FIG. 7).

  A spherical driving wheel 5 having a radius larger than the step on the inner peripheral surface of the pipe to be traveled is attached to the tip of the arm module 80. The drive structure of the drive wheel 5 will be described in detail later. As the arm module 80 swings, the spherical drive wheel 5 is displaced in the near and far direction with respect to the inner peripheral surface of the pipe. A gear-type swing synchronization mechanism 9 is provided so that the swing displacements of the three arm modules 80 coincide. The swing synchronization mechanism 9 synchronizes the swing displacements of the three arm modules 80 by meshing the bevel gears 90 that rotate in conjunction with the swing displacement of the arm modules 80.

  The arm module 80 of the front arm unit 8A and the arm module 80 of the rear arm unit 8B are used as urging means to interlock the arm module 80 of the front arm unit 8A and the arm module 80 of the rear arm unit 8B. A coil spring 91 to be connected is provided. The coil spring 91 causes the spherical drive wheel 5 attached to the arm module 80 of the front arm unit 8A and the spherical drive wheel 5 attached to the arm module 80 of the rear arm unit 8B to approach the inner peripheral surface of the pipe. The arm modules 80 are brought close to each other. Thereby, the spherical drive wheel 5 contacts the inner peripheral surface of the pipe, and the traveling carriage unit 6 travels in the pipe by the driving rotation.

  A base 70 that is a core member of the carriage main body 7 of the traveling carriage unit 6 is a hollow body having a triangular cross section made of a rectangular plate material. As can be understood from FIG. 7, the arm module 80 is created by connecting the left and right half modules 80a back to back so as to sandwich the radially extending plate-like arm bracket 710 of the base 70. . At that time, the corresponding bevel gears 90 of the three arm modules 80 mesh with each other. As a result, the arm modules 80 of the front arm unit 8A and the arm modules 80 of the rear arm unit 8B oscillate in a reliable manner.

  The spherical drive wheel 5 fixed to the mounting seat 84 of the arm module 80 includes a wheel body 50 and a drive unit 56, as shown in FIG. The spherical drive wheel 5 in the assembled state is shown on the upper side of FIG. 8, and the spherical drive wheel 5 in a state where the wheel body 50 and the drive unit 56 are disassembled is shown on the lower side of FIG. Has been. The wheel body 50 is divided into a hollow left hemispherical wheel 51 and a hollow right hemispherical wheel 52. At the center of the left hemispherical wheel 51 and the right hemispherical wheel 52, bosses for fixing the axles 54a and 54b are formed. A rubber ring 53 that enhances friction between the inner peripheral surface of the pipe is fitted on the peripheral regions of the left hemispherical wheel 51 and the right hemispherical wheel 52. A drive unit 56 that drives the wheel body 50 is housed in a space bounded by the left hemispherical wheel 51 and the right hemispherical wheel 52. As apparent from FIG. 8, the outer diameter of the rubber ring 53 is larger than the outer diameters of the left hemispherical wheel 51 and the right hemispherical wheel 52. With this configuration, it is possible to satisfactorily cope with curved surface travel.

  The drive unit 56 includes a first drive unit 56a and a second drive unit 56b attached to a common unit case 55. The first drive unit 56a and the second drive unit 56b each have a motor and a gear-type reduction mechanism 58. The first drive unit 56a drives the axle 54a of the left hemispherical wheel 51, and the second drive unit 56b. Drives the axle 54b of the right hemispherical wheel 52. The unit case 55 supports the left hemispherical wheel 51 and the right hemispherical wheel 52 via the axles 54a and 54b. The unit case 55 is detachably attached to the mounting seat 84 of the corresponding arm module 80. At this time, the radius of the spherical hemispherical wheel 51 including the rubber ring 53, that is, the radius of the left hemispherical wheel 51 and the right hemispherical wheel 52 overcomes the step on the inner peripheral surface of the tube. Since it is necessary to make it larger than this, it is selected depending on the piping to be traveled, particularly according to the level difference.

〔Experimental result〕
FIG. 8 shows a C-scan image showing an experimental result obtained by inserting the ultrasonic inspection unit 1 having the above-described configuration into the tube using the stationary moving unit 6 instead of the traveling carriage unit 6. This experimental result shows that 30%, 50%, 70%, and 100% of the depth of wall thickness provided on a steel pipe having a wall thickness of 5.8 mm and an inner diameter (outer diameter) of 204.7 (216.3) mm. 4 holes of 10 mm diameter that are (through holes) and 4 holes of 5 mm diameter that are 30%, 50%, 70%, 100% of depth wall thickness (through holes) were made as artificial defects It is. From this, it can be understood that it is possible to detect a considerably thinned portion by the tube inspection apparatus using the space propagation ultrasonic wave according to the present invention.

[Another embodiment]
(1) In the above-described embodiment, one ultrasonic inspection unit 1 includes two sets of inspection heads each including the transmission probe 1A, the reception probe 1B, and the sound wave shield 28, and is 180 ° in the circumferential direction of the tube wall. Although arranged at a pitch, three sets of inspection heads may be arranged at a pitch of 120 ° in the tube wall circumferential direction. In addition, four or more sets of inspection heads may be arranged, and it is not always necessary to arrange them at an equal pitch.
(2) In the above-described embodiment, one ultrasonic inspection unit 1 is connected between the two traveling carriage units 6, but a plurality of ultrasonic inspection units 1 may be connected. 6 may be one.
(3) Also in the traveling cart unit 6, in the above-described embodiment, the three arm modules 80 are arranged at intervals of 120 ° in each of the front arm unit 8A and the rear arm unit 8B. An arrangement of arm module 80 or four or more arm modules 80 may be employed.

  The present invention is applied to an in-pipe ultrasonic inspection apparatus that inspects a pipe wall while running inside a pipe by a single-sided oblique transmission method using ultrasonic waves propagating in space.

1: Ultrasonic inspection unit 1A: Transmission probe 1B: Reception probe 10: Cart body 11: Transmission probe holding unit 12: Reception probe holding unit 2: Base 20: Arm base (base)
21: First arm (base)
22: Second arm (base)
23: Base bracket (base)
24: Slide mechanism 241: Slide rail 242: Slider 243: Plunger spring 244: Spring stopper 28: Sonic shield 30: Movable base (base)
31: Case body 32: Revolving body 33: Projection 34: Adjustment screw 4: Guide part 5: Drive wheel 6: Traveling cart unit 6A: Front traveling cart 6B: Rear traveling cart 72: Connecting member 8: Arm unit 100: Inspection Evaluation department

Claims (7)

An in-pipe ultrasonic inspection apparatus for inspecting a pipe while running inside the pipe,
A traveling carriage unit that travels on the inner peripheral surface of the pipe using a plurality of drive wheels;
A connecting member connected to the traveling carriage unit and extending in the tube axis direction of the pipe;
A base provided on the connecting member;
A guide that is supported by the base so as to be symmetric with respect to the axis of the tube, and is urged so that it can be displaced in the radial direction of the tube and always contacts the inner circumferential surface of the tube; ,
A transmission probe holding part supported by the base so as to interlock with a radial displacement of the guide part;
A receiving probe holding unit supported by the base so as to interlock with a radial displacement of the guide unit;
A transmission probe fixed to the transmission probe holding portion so that an interval in which the ultrasonic wave incident on the inner peripheral surface is spatially propagated can be kept between the inner peripheral surface;
A receiving probe fixed to the receiving probe holding unit so that an interval in which the ultrasonic wave coming out from the inner peripheral surface is spatially propagated can be kept between the inner peripheral surface;
An in-pipe traveling ultrasonic inspection apparatus.   The base includes an arm base that extends from the connecting member to both sides in the pipe radial direction, and a movable base that is supported on both sides of the arm base so as to be radially displaceable. The guide is provided on the movable base. The in-pipe traveling ultrasonic inspection apparatus according to claim 1.   The arm base includes a first arm part and a second arm part spaced apart in the tube axis direction, and the transmission probe holding part is provided on a movable base supported by the first arm part, The in-pipe traveling ultrasonic inspection apparatus according to claim 2, wherein the receiving probe holding unit is provided on a movable table supported by the second arm unit.   A sound wave shield that blocks ultrasonic waves that come out of the transmission probe and travel toward the reception probe by spatial propagation is supported between the transmission probe and the reception probe on the base. The in-pipe traveling ultrasonic inspection apparatus according to any one of claims 1 to 3.   The in-pipe traveling ultrasonic inspection apparatus according to claim 4, wherein a gap is formed between a tip of the sound wave shield and the inner peripheral surface.   6. The traveling carriage unit includes a front traveling carriage and a rear traveling carriage connected by the connecting member, and the base is disposed between the front traveling carriage and the rear traveling carriage. The in-pipe traveling ultrasonic inspection apparatus according to any one of the above.   The said drive wheel is attached to the edge part of the some support arm extended radially from the said connection member to the radial direction of the pipe | tube at intervals in the circumferential direction of the said pipe | tube. The in-pipe traveling ultrasonic inspection apparatus described in 1.

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