JP2009294219A - Method of measuring plate thickness and inspection device for measuring plate thickness - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of measuring plate thickness of an internal tank of a double-structured container consisting of an external tank and the internal tank with different plate thickness by transmitting and receiving ultrasonic pulses. <P>SOLUTION: An ultrasonic transmission substance 9 is filled in the gap between the external tank 1b and the internal tank 1a, after thatthe ultrasonic pulses are transmitted and received in the internal tank 1a direction by an ultrasonic sensor 5, the ultrasonic pulse signal groups, the amplitude intensity of ultrasonic pulse signals received and recorded by the ultrasonic sensor 5 of which is attenuated according to the elapsed time, and its time interval ΔT are determined. Then, the time interval between an ultrasonic pulse signal A which is not belonging to the ultrasonic pulse signal group and not belonging to the ultrasonic pulse signal A recorded first and not belonging to the ultrasonic pulse signal group, the time interval with the ultrasonic pulse signal A is not ΔT, and the time interval of the ultrasonic signal recorded first is determined, and the plate thickness of the inner tank 1a is computed using the time interval and the propagation speed of ultrasonic pulses. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for measuring the thickness of an inner tank of a double-structured container composed of an outer tank and an inner tank by transmitting and receiving ultrasonic pulses, and an inspection apparatus for the thickness, and in particular, a person cannot easily approach it. It is suitable for a method of measuring the thickness of an inner tank of a container composed of an outer tank and an inner tank having different thicknesses installed in a place or partition wall by transmitting and receiving ultrasonic pulses, and an inspection apparatus for the thickness.

  A typical example of such a container is a double structure container that handles radioactive substances in a reprocessing facility.

  Thickness inspection of structures using ultrasonic sensors is widely used in various industrial fields for evaluating the soundness of plant structures and storage tanks. However, in large structures such as chemical plant distillation towers, oil tanks and tankers, there are many cases where the main body is covered with metal containers to keep the main body warm and prevent leakage of internal substances. Since ultrasonic waves do not propagate through the gap between the outer containers, when measuring the thickness of the main body, the internal material must be removed and the thickness of the main body must be measured from the inside. ing.

  In addition, even if it is not a double structure as described above, a two-layer structure where the surface of the structure is coated in layers to prevent corrosion due to internal substances, etc. When measuring the thickness of an object, a large number of ultrasonic waves reflected at the interface are received depending on the structure, and simply from the time when the reflected waves are received and the propagation speed of the ultrasonic waves inside the container, Thickness cannot be evaluated. The following contents can be cited as conventional techniques for measuring the plate thickness in such a case.

  Hereinafter, signal processing in the prior art will be described with reference to FIG. FIG. 16A shows a plate thickness measurement method in the case where the scale 410 is attached to the surface of the structure 400 that is the plate thickness measurement target. An ultrasonic wave is oscillated with the ultrasonic sensor 5 in contact with the outer surface of the scale 410, and the intensity of the ultrasonic signal reflected by the signal processing device is recorded with time. At this time, a signal as shown in FIG. 16B is recorded. The signals obtained in order from the left side of the figure will be described. First, the vibration of the ultrasonic sensor 5 itself, the ultrasonic wave reflected from the interface between the ultrasonic sensor 5 and the scale 410, and the scale 410 are very thin. A signal by an ultrasonic wave reciprocating inside 410 is recorded almost simultaneously with the transmission of the ultrasonic wave. Next, an ultrasonic wave 420a reciprocating in the structure 400 and a series of signals by ultrasonic waves reciprocating in the scale 410 are recorded. The earliest ultrasonic path recorded in the series of ultrasonic signals is an ultrasonic wave 420a signal having a short propagation distance. Similarly, a series of ultrasonic signals including ultrasonic waves that reciprocate a plurality of times inside the structure 400, for example, 420b and 420c, are recorded. Accordingly, if the signal rise interval ΔT is obtained from the series of ultrasonic signals, ΔT corresponds to the propagation time of the ultrasonic waves that reciprocate inside the structure 400, so the plate thickness is ΔT × ultrasonic propagation speed ÷ 2 (e.g., see Patent Document 1).

  In addition, a similar example in the prior art of means for allowing an ultrasonic sensor or the like to reach the outer surface of the inner layer through a thin tube connected to the outer tank of a double-structured container consisting of an outer tank and an inner tank whose thickness is to be measured As a method, a plurality of miniature bearings are arranged radially on the outer peripheral surface of the flexible insertion tube connected to the sensor unit to reduce the frictional force with the tube wall (see, for example, Patent Document 2).

JP 2002-39732 A JP-A-7-167982

  However, the signal as shown in FIG. 16B is recorded only when the time for the ultrasonic wave to reciprocate within the scale 410 is shorter than the time for the ultrasonic wave to reciprocate within the structure 400. When the scale 410 is very thick and the time for the ultrasonic wave to reciprocate within the scale 410 is the same as the time for the ultrasonic wave to reciprocate within the structure 400, the aspect of the signal obtained is completely different.

  The plate thickness measurement object of the present invention is a double-structured container composed of an outer tub 1b and an inner tub 1a as shown in a circle drawn by a broken line in FIG. 1, and there is a gap between the outer tub 1b and the inner tub 1a. Therefore, the ultrasonic wave does not propagate, and the ultrasonic wave entering from the outer surface of the outer tank 1b is not transmitted to the inner tank 1a as it is. Also, even if the structure is such that the gap is filled with an ultrasonic transmission material from the beginning, the aspect of the signal obtained is completely different, the signal processing of the above prior art cannot be applied, and the plate thickness of the inner tank Cannot be evaluated.

  Therefore, the problem to be solved by the present invention is that a method and an inspection apparatus for measuring the thickness of the inner tank of a double-structured container composed of an outer tank and an inner tank having different thicknesses by transmitting and receiving ultrasonic pulses are conventionally used. It is in a point not found. Specifically, the ultrasonic pulse is not transmitted to the inner tank due to the gap between the inner tank and the outer tank of the double structure container. Moreover, even if an ultrasonic pulse is transmitted to the inner tank, the thickness of the inner tank cannot be measured unless the received signal processing is appropriately performed. Furthermore, in the case of a double structure container that handles radioactive substances in a place where people cannot easily approach it or in a reprocessing facility installed inside the partition wall, an ultrasonic sensor is brought close to the double structure container from a distance, A means for pressing the ultrasonic sensor against the measurement object is required.

  Another problem is that if there is a pipe connected to the outer tank surface for supplying steam etc. to the gap between the inner tank and the outer tank of the double-structured container, a curved part such as an elbow when traveling in the pipe No inspection device has been found that has a degree of freedom to move freely according to the pipe shape and can press the ultrasonic sensor against the inner tank surface with a predetermined force when measuring the plate thickness.

  In addition, in order to insert the sensor part from the sensor insertion port of a small-diameter pipe where there are multiple elbow parts with small curvature radii to the inspection site far away, the insertion force applied at the sensor insertion port is effectively transmitted to the tip part. Need to be done. However, in piping with a small pipe diameter, it has been difficult to produce a miniature bearing as used in the prior art on the outer periphery of the sensor unit.

  As an alternative, a means for fixing and inserting a sensor at the tip of a spring wire or a shape memory alloy wire having superelastic characteristics with little plastic deformation due to deformation can be considered, but the problem with such a simple method is If the frictional force due to the contact between the tip and the inner wall surface of the elbow exceeds a predetermined value, the wire buckles between the tip and the insertion port, and the insertion force is not sufficiently transmitted to the tip. .

  In order to solve the above problems, an ultrasonic wave transmitting substance is filled in the gap between the outer tank and the inner tank so that the ultrasonic waves entering from the outer surface of the outer tank are transmitted to the inner tank. Preferably, the ultrasonic transmission material is a harmless liquid such as water. Then, an ultrasonic pulse is transmitted / received by an ultrasonic sensor from the outer surface of the outer tub, and an ultrasonic pulse signal is recorded with time. As signal processing of the recorded ultrasonic pulse signals, (1) among the recorded ultrasonic pulse signals, an interval ΔT between a series of ultrasonic pulse signal groups whose amplitude intensity is attenuated according to the elapsed time is obtained (2 ) The time when the ultrasonic pulse signal group is recorded or the time when the ultrasonic pulse signal group is expected to be recorded is obtained using the interval ΔT, and (3) at a time different from the time obtained in (2). Of the recorded ultrasonic pulse signals, the first recorded ultrasonic pulse signal (ultrasonic pulse signal A) is obtained, and (4) an ultrasonic pulse recorded at a time different from the time obtained in (2) above. Among the signals, the interval between the ultrasonic pulse signal A is not ΔT and the first recorded ultrasonic pulse signal (ultrasonic pulse signal B) is obtained. (5) Ultrasonic pulse signal A and ultrasonic pulse signal B The interval ΔT ′ between It is obtained so as to evaluate the thickness of the inner tub from ([Delta] T '× ultrasonic propagation velocity / 2).

  As signal processing of the recorded ultrasonic pulse signal, (1) among the recorded ultrasonic pulse signals, an interval ΔT between a series of ultrasonic pulse signal groups whose amplitude intensity is attenuated according to the elapsed time is obtained ( 2) Obtain the time when the ultrasonic pulse signal group is expected to be recorded from the time when the ultrasonic pulse signal group was recorded or the interval ΔT, and (3) record it at a time different from the time of (2). Among the recorded ultrasonic pulse signals, the first recorded ultrasonic pulse signal (ultrasonic pulse signal A) is obtained, and (4) among the ultrasonic pulse signals recorded at a time different from the time of (2). The interval between the ultrasonic pulse signal A is not ΔT and the first recorded ultrasonic pulse signal (ultrasonic pulse signal B) is obtained, and (5) recorded at a time different from the time of (2). Ultra of ultrasonic pulse signal The interval between the wave pulse signal A is not an integral multiple of ΔT, the interval between the ultrasonic pulse signal B is not ΔT, and an ultrasonic pulse signal (ultrasonic pulse signal C) recorded first is obtained (6 ) Obtain an interval ΔT ′ between the ultrasonic pulse signal A and the ultrasonic pulse signal C, and evaluate the plate thickness of the inner tank from the formula (ΔT ′ × ultrasonic propagation velocity / 4), or the ultrasonic pulse An interval ΔT ′ between the signal B and the ultrasonic pulse signal C may be obtained, and the thickness of the inner tank may be evaluated from the equation (ΔT ′ × ultrasonic propagation speed / 2).

  Since one of these two signal processings can identify two ultrasonic pulse signals for evaluating the thickness of the inner tank and determine the interval between the two ultrasonic pulse signals, it is known in the literature. The plate thickness of the inner tank can be obtained using the propagation speed of ultrasonic waves according to the material of the inner tank. At that time, if the environmental temperature is measured or known, the thickness of the inner tank can be obtained more accurately by using the propagation speed of the ultrasonic wave at that temperature in the literature.

  Preferably, when the outer tub and the inner tub are made of the same material and the thickness D of the outer tub is known, the propagation speed of the ultrasonic wave used for evaluating the thickness of the inner tub is obtained by signal processing. It is desirable to use a value obtained from the equation (D / ΔT) using ΔT. This is because an accurate inner tank thickness can be obtained even when the ambient temperature is unknown or the temperature dependence of the ultrasonic wave propagation speed is unknown.

  As an inspection apparatus for realizing the above-described plate thickness measurement method, transmission / reception means for transmitting / receiving ultrasonic pulses, recording means for recording ultrasonic pulse signals together with time, and the above signals for the recorded ultrasonic pulse signals It comprises signal processing means for processing.

  Also, move the ultrasonic sensor from a location away from the double-structured container to the vicinity of the outer tank of the double-structured container, and press the ultrasonic sensor to an arbitrary position on the outer tank surface where there are no pipes or support members, and record The above-described signal processing is performed on the ultrasonic plate pulse signal. As a result, the ultrasonic sensor can be placed at an arbitrary position where there is no pipe or support member on the outer tank surface by remote control from a distance with respect to a double structure container installed in a place where the person cannot easily approach or inside the partition wall. Since it can be pressed, the thickness of the inner tank can be measured remotely.

  As an inspection apparatus for realizing the above plate thickness measuring method, in addition to the above-described inspection apparatus, a moving means for moving the ultrasonic sensor from a place away from the double structure container to the vicinity of the outer tank of the double structure container A pressing means is provided for pressing the sonic sensor at an arbitrary position on the outer tank surface where there is no piping or support member.

  In order to achieve the above-mentioned other purposes, an ultrasonic sensor is inserted into the pipe connected to the outer tank from a distance, and the ultrasonic sensor is pressed on the inner tank surface that opposes the pipe. The thickness of the inner tank at the pipe connection position is evaluated.

  As an inspection device for realizing the above-described plate thickness measuring method, an insertion means for inserting an ultrasonic sensor into a pipe connected to the outer tank from a distance of the double structure container, an inner tank that opposes the ultrasonic sensor to the pipe A pressing means for pressing on the surface and a signal processing means for evaluating the thickness of the inner tank by transmitting and receiving ultrasonic waves are used. In this case, the insertion unit and the pressing unit may be integrated.

  The insertion means is provided with an ultrasonic sensor for measuring the plate thickness at the tip, a sensor holder provided with a roller on the circumferential surface, and connected behind the sensor holder to bend freely in a plane. Further, an alignment mechanism, a shape memory alloy wire connected to the alignment mechanism, and a feeding means for feeding out the shape memory alloy wire are provided behind the joint. The mechanical friction force when traveling inside the pipe can be reduced by the roller of the leading sensor holder. In addition, when inserted into the pipe by the alignment mechanism, the sensor holder and joint connected to the alignment mechanism are automatically positioned at the center in the radial direction of the pipe. Can proceed. Furthermore, since the joint bends automatically according to the shape of the elbow portion, the progress is not hindered even if the elbow portion exists in the pipe.

  The pressing means is connected to the shape memory alloy spring A connected to the ultrasonic sensor so as to bend freely in a plane, but one side of the connecting portion can be pushed out by the shape memory alloy spring B. A plurality of joints having a pin and a pin insertion hole on the other side, a support portion that can be opened and closed by a shape memory alloy spring C, and shape memory alloy springs A, B, and C for current flow With a power supply. The shape memory alloy spring C is energized and heated to widen the support portion, so that the support portion hangs on the peripheral wall of the pipe outlet, and the shape memory alloy spring B is energized and heated to insert the pin into the hole and the joint is inserted. It is fixed straight. In this state, when the shape memory alloy spring A is energized and heated to push out the ultrasonic sensor, it is brought into contact with the inner tank surface that opposes the pipe, and the pressing force can be received by the support portion.

  Further, the ultrasonic sensor insertion means includes a shape memory alloy wire having super elastic characteristics for inserting the ultrasonic sensor to the plate thickness measurement position of the inner tank, and a tip portion of the wire or a predetermined interval along the wire. An ultrasonic sensor integrated with the fixed rotating means and the rotating means fixed to the tip of the wire is provided. When the rotating part of the rotating unit comes into contact with the inner wall of the tube into which the sensor is inserted, the rotating unit can insert the wire with little frictional force due to the rotational motion.

  Furthermore, since the rotating means is provided so that the wheel rotating by contact with the inner wall of the pipe can freely rotate in the circumferential direction of the wire, it is appropriate to follow the bending of the pipe regardless of the direction of the bending of the pipe. Can rotate in any direction.

  In addition, the ultrasonic sensor insertion means includes vibration applying means for remotely applying mechanical vibration to the rotation means fixed to the tip of the ultrasonic sensor insertion wire, and the insertion property of the rotation means is deteriorated. Vibration can be generated at the time, and the ultrasonic sensor can be inserted more smoothly.

  According to the plate thickness measuring method and the plate thickness inspection apparatus of the present invention, the outer tub and the inner vessel having different thicknesses such as a double-structured container that handles radioactive substances in a reprocessing facility that could not be measured conventionally. The plate thickness of the inner tank of the double structure container composed of the tank can be measured by transmitting and receiving ultrasonic pulses.

1 is a schematic view of a double-structure container and a plate thickness inspection apparatus according to a first embodiment of the present invention. It is a figure which shows the kind of propagation path of the ultrasonic pulse by 1st Example of this invention. It is a figure which shows the ultrasonic pulse signal recorded by 1st Example of this invention. It is the figure which expanded the one part area | region of FIG. It is a wave form diagram of an ultrasonic pulse signal by the 1st example of the present invention. It is an apparatus block diagram of the plate | board thickness inspection apparatus by 2nd Example of this invention. It is an apparatus block diagram of the plate | board thickness test | inspection apparatus by 3rd Example of this invention. It is an apparatus block diagram of the plate | board thickness test | inspection apparatus by 4th Example of this invention. It is an apparatus block diagram of the plate | board thickness test | inspection apparatus by 5th Example of this invention. It is an apparatus whole block diagram of the plate | board thickness test | inspection apparatus by 7th Example of this invention. It is an apparatus block diagram of the plate | board thickness test | inspection apparatus by 6th Example of this invention. It is a block diagram of the joint fixing | fixed part of the plate | board thickness test | inspection apparatus by 6th Example of this invention. It is an apparatus block diagram of the plate | board thickness test | inspection apparatus by 7th Example of this invention. It is function explanatory drawing of the plate | board thickness test | inspection apparatus by 7th Example of this invention. It is an apparatus block diagram of the plate | board thickness inspection apparatus by 8th Example of this invention. It is explanatory drawing of the plate | board thickness measuring method by a prior art example.

  The purpose of measuring the thickness of the inner tank of a double-structured container consisting of an outer tank and an inner tank with different thickness installed in a place where humans cannot easily approach is by sending and receiving ultrasonic pulses. It was realized by processing the obtained ultrasonic pulse signal and introducing an ultrasonic sensor from a distance of the double structure container. Specific examples will be described below.

  FIG. 1 is a configuration diagram of a plate thickness measuring method and an inspection apparatus according to an embodiment of the present invention. The double-structured container 1 as an inspection object is installed inside a concrete partition wall 2 incapable of entering by humans for protection against radiation exposure. There is a heating coil 4 for heating the nitric acid solution inside the double-structured container 1, and the thickness of the inner tank 1a in the vicinity of the heating coil 4 is reduced due to corrosion. It is necessary to measure the plate thickness. However, since the inner tank 1a is covered with the outer tank 1b for heat insulation, and there is a gap between the inner tank 1a and the outer tank 1b, usually an ultrasonic wave is transmitted from the outer surface of the outer tank 1b to the inside. However, the ultrasonic waves do not reach the inner tank 1a.

  In the present embodiment, the ultrasonic wave transmitted from the ultrasonic sensor 5 is transmitted to the inner tank 1a as in the ultrasonic path 10, for example, by filling the gap with an ultrasonic transmission material 9 represented by water, for example. . If it is the outer surface of the outer tub 1b without the pipe 3 connected to the outer tub 1b, it can be attached at an arbitrary position like the ultrasonic sensors 5a, 5b, 5c.

  Since the concrete partition wall 2 is normally closed but has an openable portion 6, the cable 7 of the ultrasonic sensor 5 can be laid outside the concrete partition wall 2 by using this. This cable 7 is connected to the control device 8 of the ultrasonic sensor 5, the oscilloscope 11, the personal computer 12 and the monitor 13. In this embodiment, the control device has a configuration in which a plurality of devices described below are integrated, but of course, there is no problem even if the control device is configured by a plurality of devices. That is, a pulsar 8a that oscillates an ultrasonic pulse by the ultrasonic sensor 5, a receiver 8b that receives a trigger signal from the pulsar 8a and receives an ultrasonic pulse reflected by the ultrasonic sensor 5, and a received ultrasonic pulse signal. A signal amplifier 8c for amplifying and a signal filter 8d for frequency-filtering the ultrasonic pulse signal. In this embodiment, since 10 MHz is used as the frequency of the ultrasonic pulse, a band-pass filter whose center frequency of the transmitted signal is 10 MHz is used as the signal filter 8d.

  The ultrasonic pulse signal subjected to the frequency filter processing is converted into a digital signal by the oscilloscope 11 and taken into the personal computer 12 to perform signal processing for evaluating the plate thickness of the inner tank 1a. The signal processing result and plate thickness during the process are displayed on the monitor 13.

  Signal processing of the ultrasonic pulse signal in this embodiment will be described with reference to FIGS. 2 is a propagation path of ultrasonic waves, FIG. 3 is a recorded ultrasonic pulse signal, and FIG. 4 is an enlarged view of a region in FIG. 3 where signals from the inner tank are superimposed.

  When the recording of the received ultrasonic pulse signal is started simultaneously with the transmission of the ultrasonic pulse, the ultrasonic wave reflected at the interface between the ultrasonic sensor 5 and the outer tank 1b is recorded at time zero. Thereafter, signals of F100, F200, F300, etc. in which the propagation distance of the ultrasonic wave is increased in order such as one round trip, two round trips, and three round trips inside the outer tub 1b are recorded. These propagation paths are shown in FIG. 2, and the propagation distance of these ultrasonic waves increases in order by one reciprocation of the inside of the outer tank 1b, so that the recorded time intervals are equal. In the example, the interval is about 10 μs.

  Further, as the number of times of reciprocating inside the outer tank 1b increases, the ultrasonic wave is divided into reflection and transmission at the boundary surface, so the intensity Pn of the ultrasonic pulse signal reciprocating n times inside the outer tank 1b is

It is represented by Here, α is smaller than 1 although it varies depending on the material due to reflection efficiency. Accordingly, in this series of ultrasonic pulse signal groups, the number of reciprocations inside the outer tub 1b increases as time elapses, so that the ultrasonic pulse signal intensity attenuates.

  From the above, it is possible to specify an ultrasonic pulse signal group that reciprocates a plurality of times inside the outer tub 1b because the intervals are equal and the ultrasonic pulse signal intensity is attenuated according to the elapsed time.

  Next, a method of selecting an ultrasonic pulse signal for evaluating the plate thickness of the inner tank 1a in the ultrasonic pulse signal processing will be described. As shown in FIG. 4, a group of ultrasonic pulse signals reciprocated a plurality of times inside the outer tub 1b appears continuously. Since this series of ultrasonic pulse signal groups has been specified in the previous signal processing, the first ultrasonic pulse signal that does not belong to this group, F110 present in about 120 μs in this embodiment, can be selected. F110 is an ultrasonic pulse signal having a shortest propagation path among those not belonging to the ultrasonic pulse signal group and having a propagation path reflected by the boundary surface between the ultrasonic transmission substance 9 and the inner tank 1a.

  As the ultrasonic pulse signal having the shortest propagation path after F110, F210 that has propagated through the outer tank 1b from F110 to the extra roundtrip and F111 that has propagated through the inner tank 1a from F110 through the roundtrip extraordinary can be considered. Which is recorded first is determined by the relationship between the thicknesses of the outer tub 1b and the inner tub 1a, and when the thickness of the outer tub 1b is thinner than the inner tub 1a as in this embodiment, F210 is the first. To be recorded. Since the difference in propagation distance between F110 and F210 corresponds to one round trip of the outer tub 1b, the distance between them is ΔT. Since ΔT has been obtained in the previous signal processing, F111 recorded in the interval from F110 to ΔT is not selected, and F111 can be selected.

  From the above, F110 and F111 can be selected, and the difference between the two propagation distances corresponds to one round trip of the inner tank 1a. Therefore, if the distance between them is ΔT ′, the thickness of the inner tank 1a is ΔT It can be evaluated by '× propagation speed of ultrasonic wave ÷ 2.

  Similarly, as an ultrasonic pulse signal having a short propagation path next to F111, F310 propagated through the outer tank 1b from F110 two extra roundtrips, and F211 propagated through the outer tank 1b one extra roundtrip from F111 and the inner tank 1a from F111. F112 that propagates one round trip extra is considered. Which is recorded first is determined by the relationship between the thicknesses of the outer tub 1b and the inner tub 1a. When the thickness of the outer tub 1b is thinner than the inner tub 1a as in this embodiment, F310, F211 , F112 are recorded in this order. Since the difference in propagation distance between F110 and F310 corresponds to two reciprocations of the outer tub 1b, the distance between them is twice ΔT. Since ΔT is obtained in the previous signal processing, F310 recorded at an interval twice F110 to ΔT is not erroneously selected. Further, since the difference in propagation distance between F111 and F211 corresponds to one round trip of the outer tub 1b, the distance between the two is ΔT, so that F211 recorded at the interval from F111 to ΔT is not erroneously selected. . Therefore, F112 can be selected.

  The difference in propagation distance between F110 and F112 corresponds to two reciprocations of the inner tank 1a. Therefore, if the distance between the two is 2 × ΔT ′, the thickness of the inner tank 1a is 2 × ΔT ′ × ultrasonic propagation velocity ÷ 4. Moreover, since the difference in propagation distance between F111 and F112 corresponds to one reciprocation of the inner tank 1a, if the distance between them is ΔT ′, the thickness of the inner tank 1a is ΔT ′ × ultrasound. It can be evaluated by propagation speed ÷ 2.

  The ultrasonic wave propagation velocity used in the above measurement may be a value known as the ultrasonic wave propagation velocity of the material according to the literature according to the material of the inner tank. However, since the propagation speed of ultrasonic waves generally depends on temperature, it is difficult to evaluate the accurate propagation speed of ultrasonic waves from the literature or the like without knowing the measurement target temperature at the time of measurement. For this reason, when measurement accuracy is required, if the inner tank and the outer tank are made of the same material and the thickness D of the outer tank is known, the value of D / ΔT is transmitted as the ultrasonic wave. It is good to use as speed.

  According to the signal processing of the ultrasonic pulse signal of the present embodiment, three types of ultrasonic pulse signals F110, F111 and F112 can be selected, and by obtaining the interval between at least two of these ultrasonic pulse signals, The plate thickness of the inner tank 1a can be evaluated. An example of a method for obtaining the intervals between F110, F111, and F112 will be described with reference to FIG.

  FIG. 5 is a waveform diagram of the ultrasonic pulse signals F110, F111, and F112. In general, when the acoustic impedance of the material before the boundary surface, that is, the product of the density and the propagation velocity, is smaller than the acoustic impedance of the material after the boundary surface, the waveform of the ultrasonic wave is inverted when passing through the boundary surface. It is known that when the acoustic impedance of the material before the boundary surface is larger than the acoustic impedance of the material after the boundary surface, it does not reverse. If the ultrasonic transmission substance 9 represented by water is compared with the acoustic impedance of the metal that is the material of the inner tank 1a and the outer tank 1b, the ultrasonic transmission substance 9 is smaller. Therefore, the ultrasonic pulse signals of F111 and F112 The waveform is inverted from the waveform of F110. Therefore, if the interval between F110 and F111 or F110 and F112 is obtained from the time difference when rising to a certain signal strength, the correct interval cannot be obtained because the waveform is inverted.

  Further, even when the interval between F111 and F112, which are in-phase waveforms, is obtained, since the ultrasonic waveform differs in distortion if viewed in detail, the interval gives a different value depending on the level of signal intensity regarded as rising. .

  For this reason, the interval between the ultrasonic pulse signals is evaluated by programming so as to obtain the time difference ΔT at which the index S represented by the following equation is maximum.

It is represented by Here, G ₁ (t) and G ₂ (t) are temporal changes in the waveform of the ultrasonic pulse signal whose interval is to be evaluated, and G ₁ (t) is the ultrasonic pulse signal previously recorded out of the two. It is.

  By performing a parameter survey on ΔT that maximizes the index S, it is possible to obtain an interval ΔT that provides the best overlap over the entire waveform regardless of the phase of the two ultrasonic pulse signals. In this example, the measurement of the thickness of a metal inner tub of about 35 mm is repeated, and the standard deviation of the measured variation in thickness is evaluated as an error to obtain an error of ± 0.01 mm.

  Of course, when the accuracy of the plate thickness measurement is not required, the interval may be directly read by displaying the ultrasonic pulse signal shown in FIG. 3 or 4 on the monitor 13 or printing it.

  According to the plate thickness measuring method and the inspection apparatus shown in the present embodiment, the thickness of the inner tub of the double-structured container composed of the outer tub and the inner tub having different thicknesses, which could not be measured conventionally, is measured by ultrasonic waves. It can be measured by transmitting and receiving pulses.

  Another embodiment of the present invention will be described with reference to FIG. This embodiment is an embodiment of an apparatus for measuring the plate thickness of the inner tub 1a from the outer surface of the outer tub 1b of the double structure container to be inspected installed inside the concrete partition wall 2. In addition, since the signal processing method of an ultrasonic pulse signal is the same as that of Example 1, description of a signal processing method is abbreviate | omitted below.

  In the present embodiment, the ultrasonic transmission substance is filled between the outer tub 1b and the inner tub by remote operation, and then the transfer is possible along the rail 200 provided around the inspection target inside the concrete partition wall 2. The plate thickness of the inner tank 1a is measured using the multi-degree-of-freedom arm 220a attached to the carriage 280 and the ultrasonic sensor 5 attached to the tip thereof. The rail 200 may be preliminarily laid as equipment, or may be newly laid from the equipment carry-in port 240.

  The transport carriage 280 and the multi-degree-of-freedom arm 220a are introduced into the inside from an equipment carry-in port 240 provided in the concrete partition wall 2. 6A shows the posture of the multi-degree-of-freedom arm 220a immediately after being carried into the concrete partition wall 2 from the equipment carry-in port 240, and FIG. 6B shows the position of the multi-degree-of-freedom arm 220a moved to the inspection target location. An example of the arm posture at the time of inspection by the ultrasonic sensor 5 after the inspection is shown. The ultrasonic sensor 5 has a total of 5 degrees of freedom, ie, a degree of freedom of 3 degrees of freedom of the joint 220 of the multi-degree-of-freedom arm 220a, rotation of one degree of freedom provided at the mechanical connection between the arm and the conveyance carriage 280, and one degree of freedom of movement of the carriage 280 Depending on the degree, it can be positioned at any location on the bottom of the outer tub 1b. However, when the attitude of the ultrasonic sensor 5 is fixed, the ultrasonic radiation direction of the ultrasonic sensor 5 is maintained perpendicular to the outer surface of the outer tub 1b by means of a gimbal structure or the like (not shown). Can do. In addition, the angle between the three arms and the rotation angle of the mechanical connection between the arm and the transport carriage 280 can be controlled by a motor provided in each joint and carriage.

  According to the plate thickness measuring method and the inspection apparatus shown in the present embodiment, it is difficult for a person such as a double-structured container handling a radioactive substance in a reprocessing facility that could not be measured conventionally to approach easily. The thickness of the bottom of the inner tank of the double-structured container composed of the outer tank and the inner tank of different thicknesses installed at the place can be measured by remote operation by transmitting and receiving ultrasonic pulses.

  Another embodiment of the present invention will be described with reference to FIG. Since this embodiment is different from the second embodiment in the shape of the arm of the multi-degree-of-freedom arm 220b with the ultrasonic sensor 5 attached to the tip, other description is omitted.

  In this embodiment, unlike the embodiment of FIG. 6, two degrees of freedom by a multi-degree-of-freedom arm 220 b having two arms and one degree of freedom provided at the mechanical connection between the arm and the transport carriage 280 are provided. Positioning of the ultrasonic sensor 5 is realized by a total of four degrees of freedom, that is, one degree of freedom of rotation and movement of the transport carriage 280. 7A shows the posture of the multi-degree-of-freedom arm 220b immediately after being loaded into the concrete partition wall 2 from the equipment carry-in port 240, and FIG. 7B shows the position of the multi-degree-of-freedom arm 220b moved to the inspection target location. An example of the arm posture at the time of inspection by the ultrasonic sensor 5 after the inspection is shown.

  The reason why the multi-degree-of-freedom arm 220b has two arms as in this embodiment is that the space between the double-structure container and the concrete partition wall 2 is small so that it reaches the bottom of the outer tub 1b. This is because, in a multi-degree-of-freedom arm having a book arm, the length of the arm is too long and the ultrasonic sensor 5 cannot be pressed against the side surface of the outer tub 1b.

  According to the plate thickness measuring method and the inspection apparatus shown in the present embodiment, it is difficult for a person such as a double-structured container handling a radioactive substance in a reprocessing facility that could not be measured conventionally to approach easily. The plate thickness of the side surface of the inner tank of the double-structured container composed of the outer tank and the inner tank with different thicknesses installed at the place can be measured by remote operation by transmitting and receiving ultrasonic pulses.

  Another embodiment of the present invention will be described with reference to FIG. This embodiment differs from the second and third embodiments in that the ultrasonic sensor 5 is moved to the vicinity of the outer tub 1b of the double-structured container inside the concrete partition wall 2 and the ultrasonic sensor 5 on the outer surface of the outer tub 1b. Since there is a pressing means for pressing down, other description is omitted.

  The inspection apparatus according to the present embodiment includes a remote traveling vehicle 300 that freely travels on the floor surface inside the concrete partition wall 2 and a telescopic mechanism 320 that is installed on the traveling vehicle 300. The remote vehicle 300 is carried into the concrete partition wall 2 by filling the space between the outer tub 1b and the inner tub with an ultrasonic transmission material by remote control, and then moving to the lower portion of the transport carriage 280 moving along the rail 200. It is realized in a state of being fixed with an extendable wire or the like. The remote traveling vehicle 300 moves the transport carriage 280 along the rail 200 into the concrete partition wall 2 and then hangs the remote travel vehicle 300 from the transportation cart 280 to the floor and travels remotely to a position that requires inspection. Let The power supply and control data to the remote vehicle 300 are sent via the cable 190c. In this embodiment, the pressing of the ultrasonic sensor 5 against the outer tub 1 b is realized by the expansion / contraction mechanism 320.

  8A shows the postures of the remote traveling vehicle 300 and the telescopic mechanism 320 immediately after being carried into the concrete partition wall 2 from the equipment carry-in port 240 and after the remote traveling vehicle 300 has moved to the inspection target location. FIG. 8B shows an example of the posture of the expansion / contraction mechanism 320 at the time of inspection by the ultrasonic sensor 5.

  The reason for the expansion / contraction mechanism as in this embodiment is that when the space between the double-structured container and the concrete partition wall 2 is small, the arm length is three arms that reach the bottom of the outer tub 1b. This is because there is a possibility that the length of the wall is too long to be introduced into the concrete partition wall 2.

  According to the plate thickness measuring method and the inspection apparatus shown in the present embodiment, it is difficult for a person such as a double-structured container handling a radioactive substance in a reprocessing facility that could not be measured conventionally to approach easily. The thickness of the bottom of the inner tank of the double-structured container composed of the outer tank and the inner tank of different thicknesses installed at the place can be measured by remote operation by transmitting and receiving ultrasonic pulses.

  Another embodiment of the present invention will be described with reference to FIG. This embodiment differs from the fourth embodiment in the pressing means for pressing the ultrasonic sensor 5 on the outer surface of the outer tub 1b mounted on the remote traveling vehicle 300 that is a self-propelled mechanism.

  The remote vehicle 300 is brought into the concrete partition wall 2 by filling the space between the outer tub 1b and the inner tub by remote control with an ultrasonic transmission material, and then at the lower part of the transport carriage 280 moving along the rail 200. It is realized in a state where it is fixed with a wire that can be extended. The remote traveling vehicle 300 moves the transport carriage 280 along the rail 200 into the concrete partition wall 2 and then hangs the remote travel vehicle 300 from the transportation cart 280 to the floor and travels remotely to a position that requires inspection. Let The power supply and control data to the remote vehicle 300 are sent via the cable 190c. In this embodiment, the pressing of the ultrasonic sensor 5 against the outer tub 1b is realized by an expansion / contraction mechanism 320 and a multi-degree-of-freedom arm 220a having three arms. 9 (a) shows the remote vehicle 300, the telescopic mechanism 320, and the multi-degree-of-freedom arm immediately after being loaded into the concrete partition wall 2 from the equipment carry-in port 240 and after the remote vehicle 300 has moved to the inspection target location. FIG. 9B shows an example of the posture of the expansion / contraction mechanism 320 and the multi-degree-of-freedom arm 220a at the time of inspection by the ultrasonic sensor 5. FIG. By using the structure of the expansion / contraction mechanism 320 and the multi-degree-of-freedom arm 220a as in this embodiment, if the space between the double-structure container and the concrete partition wall 2 is sufficient, the outer tank can be formed with a single inspection device. The measurement range can be greatly expanded, such as the bottom and side surfaces of 1b.

  According to the plate thickness measuring method and the inspection apparatus shown in the present embodiment, it is difficult for a person such as a double-structured container handling a radioactive substance in a reprocessing facility that could not be measured conventionally to approach easily. The thickness of the bottom and side surfaces of the inner tank of the double-structured container composed of the outer tank and the inner tank of different thicknesses installed at the place can be measured by remote operation by transmitting and receiving ultrasonic pulses.

  Example 7 in FIG. 10 and Example 6 in FIG. 11 are configuration diagrams of the plate thickness inspection apparatus of the present invention. In any embodiment, the ultrasonic sensor 5 is inserted from the sensor insertion port 28 into the drain pipe 20 provided at the bottom of the outer tub 1b of the double structure container 1, and the thickness of the bottom of the inner tub 1a is increased. taking measurement. The sixth and seventh embodiments are different from the first embodiment in that the ultrasonic sensor 5 is directly brought into contact with the outer surface of the inner tank 1a to measure the plate thickness, but the basic configuration of the signal processing apparatus for transmitting and receiving ultrasonic waves is implemented. Same as Example 1.

  First, Example 6 will be described. An embodiment of pressing the ultrasonic sensor 5 on the outer surface of the inner tank 1a according to the sixth embodiment will be described with reference to FIGS. FIG. 11 shows a shape memory alloy wire (hereinafter simply referred to as a shape memory alloy wire) 180 having superelastic characteristics using a pipe connected to the outer tank 1b to be inspected, for example, a drain pipe 170 at the bottom. The mechanism which makes the ultrasonic sensor 5 arrive at the outer surface of the inner tank 1a which opposes a pipe connection position using the insertion means which employ | adopts and inserts an ultrasonic sensor is shown.

  There are about 10 elbow parts between the place where the ultrasonic sensor 5 can be introduced and the place where the inspection object is installed, and it is difficult to insert the ultrasonic sensor 5. In this embodiment, the tip portion of the shape memory alloy wire 180 is fixed to the center portion of the sensor holder 114, and the ultrasonic sensor 5 for measuring the thickness of the inner tank 1 a is provided in the sensor holder 114. A spring made of a shape memory alloy (hereinafter simply referred to as a shape memory alloy spring) 110a for pressing the ultrasonic sensor 5 against the inner tank 1a with a predetermined force is disposed.

  In the circumferential direction of the sensor holder 114, a guide roller 112 for reducing friction with the tube wall of the sensor holder 114 is attached. The joint 140 is for mechanically connecting the sensor holder 114 and the support plate 150 and flexibly responding to the bending at the in-pipe elbow. The ball caster 120 is provided to reduce friction between the joint 140 and the tube wall at the elbow portion. The bearing 130 has an outer ring fixed to the sensor holder 114, an inner ring fixed to the frontmost joint 140, and the four joints can be freely rotated according to the bending direction at the elbow portion. . In addition, the current supply to the shape memory alloy springs 110a and 110b applied in this embodiment can be performed via the cable 190a, and the shape memory alloy springs 110a and 110b are energized and heated to extend the springs. Can do.

  On the other hand, in order to press the ultrasonic sensor 5 against the inner tank 1a, a mechanism for receiving the reaction force of the shape memory alloy spring 110a is required. The support plate 150 receives this reaction force. The support plate 150 is tilted upward when the shape memory alloy spring 110b below the slide guide 152 is at room temperature. However, the support plate 150 is stretched by heating the shape memory alloy spring 110b by applying a current to the shape memory alloy spring 110b. It is configured to collapse in the horizontal direction. The alignment mechanism 160 is provided so that the support plate 150 mounting portion is disposed in the center of the drain pipe 170 so that the support plate 150 is surely applied to the inner surface of the outer tub 1b. Thus, since the position of the lower end portion of the joint 140 is fixed on the inner surface of the outer tank by the support plate 150, it is possible to reliably press the ultrasonic sensor 5 against the inner tank 1a portion that opposes the pipe connection position. .

  FIG. 12 shows the means for fitting 140 to be aligned straight. The joints 140 and the joints 140 and the bearings 130a and 130b are pivotally supported by a rotation shaft 140a so as to be rotatable in a direction perpendicular to the paper surface of FIG. In order to align such a joint 140 in a straight line, simply connecting the four joints is not achieved. A push spring 144, a shape memory alloy spring 110c, and a joint lock pin 142 are arranged at a place where the four joints 140 are connected, and the joint lock pin is caused by the extension of the spring caused by heating the shape memory alloy spring 110c by passing an electric current. By extruding 142 upward, the bending between the two joints and between the joint and the bearing is stopped.

  Since the four joints shown in FIG. 11 need to freely rotate corresponding to the bending direction at the elbow portion, the four joints are connected to the inner rings of the bearings 130a and 130b at both ends. Yes. In order to pass a current through the shape memory alloy spring 110c attached to the four joints 140 that freely rotate, the bottom joint in FIG. 12 has two cylindrical joints fixed to the inner ring of the bearing 130b. A metal brush 132 is attached in such a manner that a slip ring 131 is arranged and brought into contact with the slip ring. The cables taken out from the shape memory alloy springs 110c attached to the four joints are electrically connected in parallel and guided to the two slip rings 131. 12A shows the position of the joint lock pin 142 in a state where each joint 140 bends freely, and FIG. 12B shows the state where each joint 140 is fixed by the joint lock pin 142.

  From the above, the pipe connected to the outer tank 1b to be inspected is used to insert the ultrasonic sensor such as the shape memory alloy wire 180 into the inner tank 1a that opposes the pipe connection position. It is possible to make the ultrasonic sensor 5 reach the outer surface and press the ultrasonic sensor 5 to the outer surface of the inner tank 1a with a predetermined pressure. In this state, by transmitting and receiving ultrasonic waves from the ultrasonic sensor 5 and recording ultrasonic pulse signals, it is possible to measure only a plurality of ultrasonic pulse signals reciprocating in the inner tank 1a. Therefore, if the interval between two measured ultrasonic pulse signals adjacent to each other is evaluated, the plate thickness of the inner tank 1a can be evaluated by (interval × ultrasonic propagation velocity ÷ 2).

  Another embodiment relating to the plate thickness inspection apparatus of the present invention will be described with reference to FIGS. 13, 14 and 15. FIG. FIG. 13A is an ultrasonic sensor that employs a shape memory alloy wire 180 having superelastic characteristics using a pipe connected to the outer tank 1b to be inspected, for example, a drain pipe 170 at the bottom. The mechanism which makes the ultrasonic sensor 5 arrive at the outer surface of the inner tank 1a which opposes a pipe connection position using the insertion means which inserts is shown.

  In this embodiment, the tip portion of the shape memory alloy wire 180 is fixed to the center portion of the guide wheel 40a, and the ultrasonic sensor 5 for measuring the thickness of the inner tank 1a is arranged on the guide wheel 40a. ing. FIG. 14B shows an embodiment of the arrangement and mechanism of the guide wheels 40a and 40b in the drain pipe 170. The guide wheel 40 includes a wire fixing portion 41, a circumferential rotation bearing 42, a circumferential rotation body 43, a wheel shaft 44, a wheel bearing 45, and a wheel 46.

  The wire fixing portion 41 is fixed to the inner ring of the circumferential rotation bearing 42, and the circumferential rotation body 43 is fixed to the outer ring of the circumferential rotation bearing 42. The wheel 46 is fixed to the outer ring of the wheel bearing 45, and the wheel shaft 44 is fixed to the inner ring of the wheel bearing 45. The guide wheel 40 passes the shape memory alloy wire 180 through a hole provided in the center of the wire fixing portion 41 and is fixed to an appropriate position of the shape memory alloy wire 180 with a nut (not shown) provided in the wire fixing portion 41. To do. An assembly of such a shape memory alloy wire 180 and the circumferential rotating body 43 is formed. An ultrasonic sensor 5 is supported on the assembly closest to the inspection position side.

  With such a mechanism, the wheels 46 arranged on both sides of the shape memory alloy wire 180 freely rotate when contacting the inner wall surface of the drain pipe 170 in the forward / backward direction of the shape memory alloy wire 180, It can also rotate freely around the superelastic alloy wire.

  FIG. 15 shows an operation state of the guide wheel 40 in the straight pipe portion and the elbow portion of the drain pipe 170. In the straight pipe portion shown in FIG. 15A, the contact between the guide wheel 40 and the inner wall surface of the drain pipe 170 occurs in some places, but the wheel 46 where the contact occurs depends on the function of the wheel bearing 45. Since little frictional force is generated between the wheel shaft 44 and the wheel shaft 44, smooth insertion is possible.

  On the other hand, in the elbow portion shown in FIG. 15 (b), the shape memory alloy wire 180 tends to move straight along the direction of the straight pipe portion because of the straight line memory function of the shape memory alloy wire 180. 40 and the inner wall surface of the drain pipe 170 are generated. However, in the frontmost wheel 40a where contact occurs, the wheel 46 rotates due to frictional force with the inner wall of the drain pipe 170 indicated by a broken line, so that the tip guide wheel 40a advances smoothly along the inner wall of the elbow. It is possible. In this case, although the ultrasonic sensor 5 is disposed in front of the guide wheel 40a, the ultrasonic sensor 5 can be set by appropriately setting the distance between the front surface of the ultrasonic sensor 5 and the wheel 46 of the guide wheel a. It is possible to insert the ultrasonic sensor 5 without causing mechanical interference between the front surface of the elbow and the inner wall surface of the elbow.

  From the above, the pipe connected to the outer tank 1b to be inspected is used to insert the ultrasonic sensor using the shape memory alloy wire 180 or the like into the outer tank 1a facing the pipe connection position. The ultrasonic sensor 5 can reach the surface. Further, propagation of ultrasonic waves between the ultrasonic sensor 5 and the inner tank 1a can be realized by using a gel-like sheet or the like attached to the surface of the ultrasonic sensor 5. In this state, by transmitting and receiving ultrasonic waves from the ultrasonic sensor 5 and recording ultrasonic pulse signals, it is possible to measure only a plurality of ultrasonic pulse signals reciprocating in the inner tank 1a.

  Another embodiment relating to the plate thickness inspection apparatus of the present invention will be described with reference to FIG. The basic configuration of the plate thickness inspection apparatus shown in FIG. 15 is the same as that of the seventh embodiment, but the change is that a vibration generator 50 is employed. That is, in this embodiment, the vibration generator 50 for generating mechanical vibrations on the guide wheel 40a of the assembly is provided in the assembly closest to the inspection position side in the seventh embodiment. As a specific example of the vibration generator 50, a small vibration motor used in a mobile phone or the like can be used. By adopting such a configuration, even when subtle interference between the guide wheel 40a at the tip and the inner wall of the drain pipe 170 occurs, such interference can be prevented by remotely adding vibration to the guide wheel 40a. Can be avoided.

  According to the plate thickness measuring method and the inspection apparatus shown in the present embodiment, it is difficult for a person such as a double-structured container handling a radioactive substance in a reprocessing facility that could not be measured conventionally to approach easily. Ultrasonic pulse indicates the thickness of the inner tank at the location facing the location where the pipe is connected to the outer tank, of the inner tank of the double-layered container consisting of an outer tank and an inner tank with different thicknesses It can be measured by remote control by sending and receiving.

  The present invention has application to a nondestructive inspection apparatus that nondestructively evaluates the thickness of the inner tank of a double-structured container having an inner tank and an outer tank using an ultrasonic pulse from the outer tank side.

  DESCRIPTION OF SYMBOLS 1 ... Double structure container, 1a ... Inner tank of double structure container, 1b ... Outer tank of double structure container, 2 ... Concrete partition wall, 3 ... Piping, 4 ... Heating coil, 5 ... Ultrasonic sensor, 5a, 5b , 5c: Example of an ultrasonic sensor brought into contact with the outer tub of the double structure container, 6 ... Opening portion of concrete partition, 7, 190a ... Cable, 8 ... Control device, 8a ... Pulser, 8b ... Receiver, 8c DESCRIPTION OF SYMBOLS ... Signal amplifier, 8d ... Signal filter, 9 ... Ultrasonic transmitting substance, 10 ... Ultrasonic path, 11 ... Oscilloscope, 12 ... Personal computer, 13 ... Monitor, 40a, 40b, 40c ... Guide wheel, 41 ... Wire fixing part , 42 ... Bearings for circumferential rotation, 43 ... Circumferential rotating bodies, 44 ... Wheel shafts, 45 ... Wheel bearings, 46 ... Wheels, 50 ... Vibration generators, 110a, 110b, 110c ... Shape memory Spring, 112 ... Guide roller, 114 ... Sensor holder, 120 ... Ball caster, 130, 130a, 130b ... Bearing, 131 ... Slip ring, 132 ... Metal brush, 140 ... Joint, 142 ... Joint lock pin, 144 ... Push spring, DESCRIPTION OF SYMBOLS 150 ... Support plate, 152 ... Slide guide, 160 ... Centering mechanism, 170 ... Drain piping, 180 ... Shape memory alloy wire, 190b ... Shape memory alloy spring heating cable, 190c ... Self-propelled mechanism cable, 200 ... Rail, 220a, 220b ... multi-degree-of-freedom arm, 240 ... equipment inlet, 280 ... conveyor truck, 300 ... remote vehicle, 320 ... extension mechanism, F100 ... ultrasonic path that makes a round trip through the outer tank, F110 ... outer tank and super Ultrasonic path to and from the inside of the sound transmission material, F111 ... outer tank, ultrasonic transmission material and inner tank Reciprocating ultrasonic path, F112 ... Ultrasonic path reciprocating once between the outer tank and the ultrasonic transmission material, and reciprocating the inner tank twice, F200 ... Ultrasonic path reciprocating the outer tank twice, F210 ... Outer tank Ultrasound path that makes two round trips and one round trip of the ultrasonic transmission substance, F211 ... Two round trips of the outer tank, ultrasonic path that makes one round trip between the ultrasonic transmission substance and the inner tank, F300 ... Ultrasonic path that makes three round trips of the outer tank Path, F310... Ultrasonic path that makes three round trips through the outer tank and one round trip through the ultrasonic transmission material.

Claims (7)

Inserting an ultrasonic sensor into the pipe connected to the outer tank of the double-structured container consisting of an outer tank and an inner tank,
The ultrasonic sensor is applied to the surface of the inner tank from the connection part of the pipe and the outer tank,
Sending and receiving ultrasonic pulses from the ultrasonic sensor to the inner tank,
A plate thickness measuring method, wherein the plate thickness of the inner tank is measured from a transmission / reception result of the ultrasonic pulse. An insertion means for inserting an ultrasonic sensor into the pipe connected to the outer tank of the double-structured container comprising an outer tank and an inner tank;
A pressing means for pressing the ultrasonic sensor from the connection between the pipe and the outer tank to the surface of the inner tank,
Signal processing means for evaluating the thickness of the inner tank based on the transmission / reception result of the ultrasonic pulse from the ultrasonic sensor to the inner tank;
Thickness inspection device with   3. The thickness inspection apparatus according to claim 2, wherein the insertion means and the pressing means are integrated. In the plate | board thickness inspection apparatus of Claim 2 or Claim 3,
A sensor holder provided with an ultrasonic sensor at the tip and having a roller on a circumferential surface; and a joint connected to the sensor holder and connected to bend freely in a plane. And an alignment mechanism connected to the joint, a shape memory alloy wire connected to the alignment mechanism and having superelastic characteristics, and a feeding means for feeding the wire. Plate thickness inspection device. In the plate thickness inspection apparatus according to claim 2 or claim 3 or claim 4,
The pressing means is connected to a spring A made of a shape memory alloy connected to an ultrasonic sensor so as to bend freely in a plane, and can be pushed out by a spring B made of a shape memory alloy at one of the connecting portions. A plurality of joints each having a pin and a pin insertion hole, a support plate that can be opened and closed by a spring C made of shape memory alloy, and the springs A, B, C made of each shape memory alloy A sheet thickness inspection apparatus comprising an electric wire for passing an electric current through the wire. In the plate thickness inspection apparatus having a signal processing means for evaluating the plate thickness based on the transmission / reception result of the ultrasonic pulse by the ultrasonic sensor,
A wire made of shape memory alloy having superelastic properties;
A circumferentially rotating body attached to the wire so as to be rotatable around the wire;
Wheels rotatably attached to the circumferentially rotating body in an arrangement with the wire interposed therebetween,
An ultrasonic sensor disposed at the tip of the assembly of the circumferentially rotating body and the wire and attached to the assembly;
Thickness inspection device with   7. The plate thickness inspection apparatus according to claim 6, further comprising vibration applying means attached to the assembly so that the assembly vibrates.

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