JP6596227B2 - Inspection apparatus and inspection method - Google Patents

Description

  The present invention relates to an inspection apparatus and an inspection method.

  In power plants, factories, or general buildings, there is an increasing demand for measuring the thickness distribution of pipes at more points from the viewpoint of maintenance of equipment such as pipes.

  According to the ultrasonic inspection method disclosed in Patent Document 1, first, a large number of support frames are attached to a pipe to be inspected. Next, the ultrasonic probe moving device is movably attached to the support frame. Then, using the motor as a drive source, the ultrasonic probe moving device is moved in the circumferential direction of the pipe on the support frame, and ultrasonic flaw detection is sequentially performed by the phased array method.

JP 2006-337151 A

The following analysis is in accordance with the present invention.
According to the ultrasonic inspection method of Patent Document 1, since it is necessary to lay a large number of support frames around the pipe, it takes time to prepare for the inspection. Moreover, there is a possibility that the support frame cannot be sufficiently arranged in the narrow space. Furthermore, since a motor is used as a drive source, there is a risk that the reliability of the apparatus may be hindered in a harsh environment.

  Thus, there is a need for an inspection method and an inspection apparatus that have a simple structure and can reduce labor required for inspection preparation.

In the first aspect, the inspection device comprises the following elements:
Rotatable screw shaft;
A slider that is screwed onto the screw shaft and is slid to move straight on the inspection target in the first direction;
A rectilinear guide for guiding the slider in the first direction so as not to rotate;
A probe attached to the slider and outputting a scan signal for inspecting a part of the inspection object;
A rotary encoder that detects a rotation angle of the screw shaft rotated in accordance with a slide operation of the slider and outputs a signal indicating a movement amount of the slider or the probe in the first direction from the rotation angle.

In the second viewpoint, the inspection method using the inspection apparatus of the first viewpoint includes the following steps:
(A) A step of operating the slider on the inspection target to intermittently move the probe in the first direction by a predetermined pitch;
(B) detecting a current position of the probe in the first direction every time the probe moves by the predetermined pitch and temporarily stops from a signal output from the rotary encoder;
(C) scanning with the probe at each position spaced apart by the predetermined pitch.

  According to the first and second viewpoints, it is possible to provide an inspection apparatus or inspection method that can be operated manually and can greatly reduce the labor required for inspection preparation.

(A) is a perspective view which illustrates the external appearance of the inspection apparatus which concerns on one Example, (B) is a side view of (A). (A) is a component diagram illustrating the inspection unit shown in FIG. 1 (A), (B) is a partial view illustrating a screw structure in the inspection unit, and (C) is a side view of (A). However, the straight guide structure in the inspection unit is shown. It is a schematic diagram explaining the principle of the rotary encoder applicable to the test | inspection unit shown to FIG. 1 (A). It is an operation figure showing typically signs that the inspection device shown in Drawing 1 (A) is running on the peripheral face of piping which is the inspection object. (A)-(C) are the schematic diagrams explaining the principle of the limit switch applicable to the magnetic wheel shown in FIG. 1, (D) is a block diagram explaining an example of the signal processing structure in an inspection apparatus. is there. (A) And (B) is a perspective view which illustrates the modification of the test | inspection unit shown to FIG. 2 (A). (A) is an operation | movement figure which shows an example of the probe holder applied to the inspection apparatus shown to FIG. 1 (A), (B) is a front view of a probe holder, (C) is the same side view. (D) is the rear view, (E) is an exploded view of the probe holder and the probe. It is a schematic diagram explaining an example of the ultrasonic flaw detection method using the test | inspection apparatus shown to FIG. 1 (A). It is a flowchart explaining the ultrasonic flaw detection method shown in FIG. It is explanatory drawing of an experimental result, (A) shows a test object, (B) shows the obtained B scope image, (C) shows the obtained C scope image, respectively.

From the above viewpoints, the following preferable modes are possible.
(Form 1) Form 1 is as in the first viewpoint. The inspector can move the slider in the first direction, preferably manually, to place the probe at an arbitrary position in the first direction, and execute the scanning operation there. The position of the probe in the first direction is detected by the rotary encoder through the rotation of the screw shaft. By repeating the slider movement operation and scanning a predetermined number of times, scanning in the first direction is completed. Since the moving pitch of the slider can be set arbitrarily, rough scanning and detailed scanning are possible. Further, the scan range in the first direction can be arbitrarily changed by changing the length of the screw shaft according to the narrowness around the scan position or the required scan range.

(Mode 2) The inspection apparatus includes a traveling unit on which an inspection unit including at least the screw shaft, the slider, and the probe is mounted. The traveling unit is a wheel that travels in the second direction intersecting the first direction on the inspection target, and a limit that limits a traveling amount of the wheel in the second direction and outputs a signal indicating the traveling amount. And a switch. The inspector moves the inspection apparatus (whole) in the second direction, preferably manually, to place the inspection apparatus at an arbitrary position in the second direction and execute the above-described scanning operation in the first direction there. Can do. The limit switch detects the position of the probe in the second direction via the wheel. The inspection on the entire inspection object is completed by repeating the movement operation and scanning in the first direction of the slider and the movement operation in the second direction of the entire inspection apparatus a predetermined number of times. In this way, the probe can scan at a predetermined two-dimensional position. For example, when an ultrasonic probe is used as a probe and ultrasonic flaw detection is performed by a reflection method, scanning is performed immediately above or close to the portion to be scanned, and an accurate C scope image (three-dimensional image) , An image in which cross-sectional images for each depth are stacked in the thickness direction can be obtained. According to the C scope image, the amount of information obtained by one inspection, for example, the amount of information related to the thickness distribution of the pipe, is significantly higher than that of the B scope image (two-dimensional image, sectional image along the depth direction). To be more. Of course, a B-scope image can also be obtained.

(Mode 3) The wheel includes front and rear wheels that can be attracted onto the inspection object by magnetic force and have different wheel diameters. The probe is supported by the slider so as to be tiltable or swingable in the first or second direction via a gimbal mechanism. By changing the front and rear wheel diameters, it becomes easy to travel on pipes of various diameters. Even when the inspection apparatus is tilted due to the difference between the front and rear wheel diameters, since the probe is supported via the gimbal mechanism, the parallelism of the probe to the inspection surface is maintained. When scanning on the peripheral surface of the inspection object, it is preferable that the wheel is attracted to the inspection object by magnetic force, hydraulic pressure, or mechanical coupling so that the inspection apparatus does not drop or shift during scanning in the first direction. As the piping to be inspected, pipes whose outer diameter is not less than that specified in A100 are preferable, but pipes to be inspected can be handled by changing the wheel diameter. Of course, a flat plate may be the inspection target.

(Mode 4) The probe is an ultrasonic probe. As other probes, probes such as eddy current flaw detection, magnetic particle flaw detection, acoustic flaw detection, or an area sensor can be used as appropriate.

(Form 5) Form 5 is as in the second viewpoint.
(Embodiment 6) In Embodiment 6, the following process is performed using the inspection apparatus as in Embodiment 2. The wheel is caused to travel in the second direction by the travel amount limited by the limit switch on the inspection target. The steps (A) to (C) concerning the second viewpoint are repeated at the position moved in the second direction.
(Embodiment 7) In Embodiment 7, scanning by the ultrasonic reflection method is performed.

  Hereinafter, one embodiment will be further described. However, the present invention is not limited to the above-described embodiments and the following examples, and can be implemented in other forms, and various embodiments can be combined.

  An embodiment of the present invention will be described below with reference to the drawings.

[Overall structure of inspection apparatus 1]
With reference to FIGS. 1A and 1B, the inspection apparatus 1 includes an inspection unit 2, a traveling unit 3, and a cable unit 4. The inspection unit 2 includes a holder unit 27 that holds the probe 28. The traveling unit 3 is mounted with the inspection unit 2 so that it can be removed or replaced. The cable unit 4 is connected to a plurality of cables for supplying power to the probe 28, the rotary encoder 25, and the limit switch 33, and performing various controls or input / output of detection signals.

[Inspection unit 2]
Referring to FIG. 2A, the inspection unit 2 includes a casing 21, a screw shaft 22 that is rotatably supported in the casing 21, a slider 23 that is screwed into the screw shaft 22, and a slider 23 that cannot rotate. And a rectilinear guide 24 for guiding in a first direction (hereinafter referred to as “scan direction”). In the inspection apparatus 1, contrary to normal, the slider 23 is operated (driven), and the screw shaft 22 is rotated (driven).

  The inspection unit 2 is further attached to the slider 23 and outputs a scan signal (hereinafter referred to as “ultrasonic probe”) 28 for inspecting a part of the inspection target, and as the slider 23 slides. A rotary encoder 25 (see FIG. 1A) that detects the rotation angle of the screw shaft 22 that is rotated and outputs a signal indicating the amount of movement of the slider 23 or the ultrasonic probe 28 in the scanning direction from the rotation angle; .

  Referring to FIG. 2B, an outer screw 22 a is formed on the outer peripheral surface of the screw shaft 22, and an inner screw 23 a that is screwed to the outer screw 22 a is formed on the inner peripheral surface of the slider 23. Referring to FIG. 2C, the casing 21 includes a rectilinear guide 24 that extends parallel to the axial direction of the screw shaft 22. The slider 23 has a guided portion 23 b provided integrally with the slider 23. When the guided portion 23b is engaged with the rectilinear guide 24, the rotation of the slider 23 is stopped and the slider 23 can move only in the axial direction of the screw shaft 22, that is, in the scanning direction.

[Specifying the position of the slider 23 in the scanning direction (screw axis direction)]
The position specification of the slider 23 in the scanning direction will be described with reference to FIGS. Referring to FIG. 1A, the rotary encoder 25 outputs a signal indicating the amount of movement of the slider 23 or the ultrasonic probe 28 in the scanning direction from the rotation angle of the screw shaft 22. The rotation angle of the screw shaft 22 is proportional to the stroke amount of the slider 23. Therefore, the rotary encoder 25 can be used to specify the position of the slider 23 or the ultrasonic probe 28 in the axial direction of the screw shaft 22 (scanning direction X shown in FIG. 4).

  With reference to FIG. 3, the measurement principle of the rotary encoder 25 will be described taking an optical case as an example. A disk 25 a having a plurality of slits 25 b formed at equal intervals is connected to the screw shaft 22. The rotation of the screw shaft 22 may be transmitted to the disk 25a via a gear mechanism. A light emitting unit 25c is disposed on one side of the disk 25a, and a light receiving unit 25d is disposed on the other side. Light is always output from the light emitting unit 25c. The light receiving unit 25d detects light that has passed through the slit 25b. The calculation unit 41 calculates the stroke amount of the slider 23 from the rotation angle of the screw shaft 22 indicated by the detection signal of the light receiving unit 25d and the screw pitch of the screw shaft 22. Therefore, if the coordinate when the slider 23 is at one end of the screw shaft is the origin of the scanning direction X, the position of the slider 23 in the scanning direction can be specified. As the rotary encoder 25, an optical, magnetic, or magneto-optical type can be used as appropriate.

[Travel unit 3]
FIG. 4 shows an example in which the inspection apparatus 1 is set on the outer peripheral surface of a pipe P that is one of inspection objects. Referring to FIG. 1B and FIG. 4, the traveling unit 3 includes a chassis 31 on which the inspection unit 2 is mounted, and front and rear wheels having different diameters, that is, a large-diameter magnetic wheel 32a and a small-diameter magnetic wheel 32b. The large-diameter magnetic wheel 32a and the small-diameter magnetic wheel 32b can travel in an index direction (circumferential direction of the pipe P) Y that intersects or is orthogonal to the scanning direction (axial direction of the pipe P) X. The large-diameter magnetic wheel 32 a and the small-diameter magnetic wheel 32 b do not fall off the pipe P and have a magnetic force that is strong enough to travel on the pipe P. At least one of the large-diameter magnetic wheel 32a and the small-diameter magnetic wheel 32b is provided with a limit switch 33 that limits a single travel distance on the piping P of the travel unit 3 or the inspection apparatus 1 and outputs a signal indicating the travel amount. It is attached.

[Identification of Index Position of Inspection Apparatus 1 (Slider 23, Ultrasonic Probe 28)]
The principle of the limit switch 33 applicable to the traveling unit 3 will be described with reference to FIGS. For example, if the one-time travel limit distance is 15 mm, the stopper 33a is turned to align the position “15” with the arrow “↓”. When the traveling unit 3 is traveled by 15 mm, the cam 33b that rotates in conjunction with the large diameter magnetic wheel 32a or the small diameter magnetic wheel 32b contacts the stopper 33a, and thereby the large diameter magnetic wheel 32a and the small diameter magnetic wheel 32b. The above rotation is restrained. Accordingly, the operation distance of the inspection apparatus 1 (slider 23, ultrasonic probe 28) in the index direction Y (see FIG. 4) can be determined from the operation of the limit switch 33. Therefore, if the first set point of the inspection apparatus 1 is the origin in the index direction Y, the index direction position of the inspection apparatus 1 (the slider 23 or the ultrasonic probe 28) can be specified. The limit switch 33 may include a brake mechanism that is provided adjacent to the large-diameter magnetic wheel 32 a and can stop the limit switch 33 and a setting switch that is disposed on the main body side of the traveling unit 3.

[Modification of inspection unit 2]
The traveling unit 3 can be equipped with the inspection unit 2 having the screw shafts 22 of various lengths according to the length of the inspection target in the scanning direction. The casing 21a shown in FIG. 1 (A) incorporates a relatively short screw shaft 22, and the casing 21b shown in FIG. 6 (A) incorporates an intermediate length screw shaft 22 (not shown). A casing 21c shown in FIG. 6 (B) incorporates a relatively long screw shaft 22 (not shown). For example, when the length in the scan direction of the inspection target is long, the movable distance in the scan direction X of the slider 22 (ultrasonic probe 28) can be achieved by adopting the casing 21c shown in FIG. It becomes longer and it is not necessary to move the traveling unit 3 in the scanning direction X. As a result, the position specifying accuracy in the scanning direction X is improved and the inspection is labor-saving.

[Probe holder and gimbal mechanism]
Referring to FIGS. 7A and 7C, a holder unit 27 is connected to the slider 23 so as to be tiltable in the vertical direction. The holder unit 27 has a bracket 27a that is swingably connected to the casing 21 via a tilt shaft 27b. Referring to FIG. 7E, the bracket 27a holds the ultrasonic probe 28 in a replaceable manner. Referring to FIG. 7B, the ultrasonic probe 28 is supported so as to be swingable in the left-right direction around the swing shaft 29. After all, the ultrasonic probe 28 is supported by the slider 28 so as to be tiltable or swingable in the scanning direction or the index direction via such a gimbal mechanism. Further, referring to FIGS. 7A and 7D, a knob 23c knurled to prevent slipping is provided at a portion where the inspector holds the slider 23. Further, a low friction member 23d is attached to a portion of the back surface of the slider 23 that slides on the casing 21 to reduce a necessary operating force.

  An example of ultrasonic flaw detection using the inspection apparatus 1 shown in FIG. 1A will be described with reference to FIGS. 8 and 9.

(Example of measurement conditions)
・ Measuring method: reflection method ・ Number of magnetic wheel travels (number of times the entire inspection apparatus 1 is moved in the index direction Y) 10 times ・ One magnetic wheel travel distance (set value of limit switch 33) 1 cm
・ Number of slides (number of times the slider 23 is moved in the scanning direction X) 10 times / index position ・ One operation distance of the slider 23 (1 pitch) 1 cm
・ Size of inspection object Width in scan direction: 10cm
Length in index direction: 10cm
Thickness: Thickness measurable by reflection method ・ Defect position: Hole whose center is coordinate (X, Y) = (5, 5) and whose depth is half of the plate thickness (the back surface to be inspected is the opening surface)

  In S101, the inspector sets 1 pitch of the slider operation to 1 cm based on the width of the inspection target / the number of slides. The inspector sets the distance of one magnetic wheel travel to 1 cm based on the length of the object to be inspected / the number of travels of the magnetic wheel. The inspector determines that the number of times the scan is executed at the same index position, that is, the number of times the slider 23 is moved, is 10 times according to the required accuracy.

  With reference to S102, the inspector places the inspection apparatus 1 on the inspection object. The inspection apparatus 1 is attracted to the inspection object by the magnetic force of the magnetic rings 32a and 32b. At this time, the coordinate (Y coordinate) in the index direction Y of the slider 23 is the origin “0”.

  With reference to S <b> 103, the inspector brings the slider 23 toward one end of the screw shaft 22. The coordinate (X coordinate) in the scanning direction X of the slider 23 (ultrasound probe 28) at this time is the origin “0”.

  Referring to S104, the inspector performs scanning (ultrasonic flaw detection). As a result, scan data at the X and Y coordinates (0, 0) is obtained.

  Referring to S105 and S106, if the slider 23 has not reached the other end of the screw shaft 22, the inspector slides the slider 23 toward the other end by one pitch. As a result, the screw shaft 22 rotates. The rotary encoder 25 detects the rotation angle of the screw shaft 22. The calculation unit 41 (see FIG. 3) calculates the movement distance of the slider 23, and eventually the X coordinate in the scanning direction in which the slider 23 has moved, from the rotation angle of the screw shaft 22.

  Note that since the current position of the slider 23 is accurately measured by the rotary encoder 25, displacement of the slider 23 due to variations in the slide operation by the inspector is allowed.

  Referring to S105 to S107, the above scanning operation is repeated, and when the slider 23 reaches the other end of the screw shaft 22 (m = 10), the scanning on the Y coordinate “0” line ends.

  Referring to S108 to S109, the inspector sets the limit switch 33 to “1 cm” and causes the traveling vehicle 1 to travel in the index direction Y in a state where it is adsorbed onto the inspection target. Referring to S110, when travel vehicle 1 travels for the set travel distance, limit switch 33 is activated and travel vehicle 1 is forcibly stopped.

  Returning to S103, the inspector brings the slider 23 toward one end of the screw shaft 22 and returns the position of the slider 23 (probe) to the origin in the scanning direction X as described above. The inspector repeats the moving operation and the scanning operation of the slider 23 a predetermined number of times (S104 to S106). When these operations are completed (S107), the limit switch 33 is set, and the traveling vehicle 1 travels in the index direction Y (S108 to S108). S109).

  When the above scan scanning and index running are completed a predetermined number of times (m = 10 and n = 10), the scanning of the range requested on the inspection object is completed, and a C scope image can be obtained. That is, referring to FIG. 5 (D), the scanning direction position of ultrasonic flaw detection can be found from the rotary encoder 25, and the index direction position of ultrasonic flaw detection can be found from the limit switch 33. A flaw detection image such as a C scope image can be obtained in combination with the scan data from the toucher 28.

  Here, the defect detection will be described. When the inspector performs a scanning operation on the line of the coordinate “4” in the index direction Y in the above-described flow, as illustrated in FIG. Therefore, a scan signal indicating a part of the hole is obtained. The same applies to the line of the coordinate “5” in the next index direction Y. By synthesizing such scan signals, a C scope image as illustrated in the lower part of FIG. 8 is obtained, the position and depth of the hole on the inspection object are specified, and the thickness distribution of the inspection object is obtained. be able to.

  In accordance with the ultrasonic flaw detection method described above, the test specimen shown in FIG. In addition, the drill hole was formed from the back surface side of the test body. A B-scope image shown in FIG. 10B was obtained by scanning scanning on a line including the drill hole. From this B scope image, the thickness distribution in the scanned cross section (cross section along the thickness direction of the specimen) can be found. Furthermore, a C-scope image shown in FIG. 10C was obtained by scanning and index running over the entire surface of the specimen. From this C-scope image, the three-dimensional wall thickness distribution of the entire specimen is known.

  As mentioned above, although embodiment and the Example of this invention were described, this invention is not limited to above-described embodiment etc., and is a further deformation | transformation in the range which does not deviate from the fundamental technical idea of this invention. Substitutions or adjustments can be made.

  It should be noted that the disclosures of the above patent documents are incorporated herein by reference. Within the scope of the entire disclosure (including claims) of the present invention, the embodiments and examples can be changed and adjusted based on the basic technical concept. Also, various combinations or selections of various disclosed elements (including each element of each claim, each element of each embodiment or example, each element of each drawing, etc.) within the scope of the entire disclosure of the present invention. Is possible. That is, the present invention of course includes various variations and modifications that could be made by those skilled in the art according to the entire disclosure including the claims and the technical idea. Further, the numerical range and the upper limit or lower limit numerical value described in the present application are not limited to the numerical value or numerical range described, and any small range or arbitrary intermediate value is described, unless otherwise specified. Shall be considered.

  The inspection apparatus and the inspection method according to the present invention are applied to various flaw detection methods such as ultrasonic flaw detection, require dust proofing, drip proofing, moisture proofing or explosion proofing, and are used in piping in a harsh environment where a short time inspection is required. It is preferably used to detect conditions such as thinning and corrosion.

DESCRIPTION OF SYMBOLS 1 Inspection apparatus 2 Inspection unit 3 Traveling unit 4 Cable unit 21 Casing 21a Short casing 21b Intermediate length casing 21c Long casing 22 Screw shaft 22a External screw, multiple thread screw 23 Slider 23a Inner screw 23b Guided portion 23c Knob 23d Low friction Member 24 Straight guide 25 Rotary encoder 25a Disk 25b Slit 25c Light emitting part 25d Light receiving part 27 Holder unit 27a Bracket 27b Tilt axis (vertical direction)
28 Probe, ultrasonic probe 29 Oscillation axis (left-right direction)
31 Chassis 32a Large-diameter magnetic wheel 32b Small-diameter magnetic wheel 33 Limit switch 33a Stopper 33b Cam 41 Calculation unit m Number of slider operations n Number of magnetic wheel travels X Scanning direction, first direction Y Index direction, second direction α Left and right necks Swing angle β Vertical tilt angle

Claims (5)

A rotatable screw shaft,
A slider that is screwed onto the screw shaft and is slid to move straight on the inspection target in the first direction;
A rectilinear guide that guides the slider in the first direction so as not to rotate;
A probe attached to the slider and outputting a scan signal obtained by inspecting a part of the inspection object;
A rotary encoder that detects a rotation angle of the screw shaft rotated in accordance with a slide operation of the slider and outputs a signal indicating a movement amount of the slider or the probe in the first direction from the rotation angle;
An inspection device comprising:
The inspection apparatus further includes a traveling unit on which an inspection unit including at least the screw shaft, the slider, and the probe is mounted.
The traveling unit is
A wheel that travels in a second direction intersecting the first direction on the inspection object;
A limit switch that limits the travel amount of the wheel in the second direction and outputs a signal indicating the travel amount;
The inspection apparatus characterized by having . The wheel can be adsorbed on the inspection object by magnetic force, and includes front and rear wheels having different wheel diameters,
The probe is supported by the slider so as to be tiltable or swingable in the first or second direction via a gimbal mechanism.
The inspection apparatus according to claim 1 . The probe is an ultrasonic probe, inspection device according to claim 1 or 2, characterized in that. A slider that is screwed onto the screw shaft and is slid to move straight on the inspection target in the first direction, a linear guide that guides the slider in the first direction so as not to rotate, and a slider that is attached to the slider and that is attached to the inspection target. A probe that outputs a scan signal that inspects a part of the probe, and a rotation angle of the screw shaft that is rotated in accordance with the slide operation of the slider, and detects the amount of movement of the slider in the first direction from the rotation angle. Preparing an inspection device having a rotary encoder that outputs a signal indicating,
(A) By operating the slider on the inspection target, the probe is moved intermittently by a predetermined pitch in the first direction;
(B) detecting the current position of the probe in the first direction every time the probe moves by the predetermined pitch and temporarily stops from a signal output from the rotary encoder;
(C) scanning with the probe at each position spaced apart by the predetermined pitch;
An inspection method,
The inspection apparatus includes a traveling unit on which an inspection unit including at least the screw shaft, the slider, and the probe is mounted, the traveling unit traveling on the inspection target in a second direction, A limit switch that limits a travel amount of the wheel in the second direction and outputs a signal indicating the travel amount,
Traveling in the second direction for the amount of travel limited by the limit switch on the inspection target,
The steps (A) to (C) are repeated at the position moved in the second direction.
Inspection method characterized by that. The inspection apparatus according to claim 4 , wherein the probe performs scanning by an ultrasonic reflection method.

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