JPH1062093A - Eddy-current inspection probe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply rotation to a part to be inspected without generating unevenness in rotation and perform a proper inspection by forming an elastic connecting part with a plurality of aligning members which are longitudinally arranged and rotatably fitted on the outer surface of an elastic hollow pipe and successively connecting the adjacent aligning members together by a plurality of universal joints. SOLUTION: The main body casing 61 of a probe body part 60 is provided with a motor 63. A slip ring 67 is attached to the output shaft of the motor 63 so that a wire 54 is connected thereto. The lead wire 54 is collected to a lead wire 65. An elastic connecting part 70 connected to the output shaft of the motor 63 and transmitting its torque to a probe head part 50 is formed with a plurality of aligning members 71 which are longitudinally arranged and rotatably fitted on the outer surface of an elastic hollow pipe. Further, the respectively adjacent aligning members 71 are successively connected together by a plurality of gimbal mechanism joints 73. Thus, rotation is transmitted to a part to be inspected without generating unevenness in rotation and a proper inspection can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an inspection apparatus for performing an eddy current inspection, and more particularly to an inspection probe used for an eddy current inspection of a thin curved pipe.

[0002]

2. Description of the Related Art In a tubular heat exchanger, a thin tube is used as a heat transfer tube, and various flaw detectors are used to non-destructively inspect the heat transfer tube for damage, defects and the like.
An eddy current inspection probe as shown in FIG. 4 is used for a heat transfer tube having a bent portion. This inspection probe 10
It is mainly formed of the inspection unit 11 at the distal end, the rotation drive unit 13 on the base end side, and the intermediate elastic connection unit 15, and has a structure suitable for being inserted into the heat transfer tube 1 having a bent portion. That is, the centering member 17 is provided at the front end and the rear end of the inspection unit 11.
, An eddy current probe 21 biased laterally by the compression coil spring 19 is provided in the middle. The inspection unit 11 is rotated about an axis to perform flaw detection as described later. The rotation drive unit 13 has a motor 29 built in a main body casing 27 supported by alignment members 25 at both ends, and its output shaft is a flexible shaft 31 of the elastic connection unit 15.
It is connected to. The flexible shaft 31 is formed by stacking multiple layers of metal wires wound in a coil shape, and is supported on the inner surface of the heat transfer tube 1 by a large number of support members 33 arranged at equal pitches in the longitudinal direction. Inspection unit 11
To rotate the probe 21. The power supply and the detection signal to the probe 21 are transmitted by a lead wire 35 wound around the flexible shaft 31. Such an inspection probe 10 is inserted into the heat transfer tube 1 via the extension tube 3 by the feeding device placed outside the heat transfer tube 1, that is, is sent in the axial direction. Part 1
When the probe 1 is simultaneously rotated, the probe 21 scans the inner surface of the heat transfer tube 1 in a spiral trajectory, and the flaw detection inspection is performed.

[0003] In the above, since a flexible shaft is used for the elastic connecting portion, there is a difficulty that the rotational transmission force is small. Therefore, a bending connection structure having a high transmission torque as shown in FIG. 5 has also been proposed. . In this case, the shaft rotatably supported by the guide short cylinder 37 is sequentially connected by a gimbal mechanism joint 39. The gimbal mechanism joint 39 allows predetermined bending, but has relatively large torsional rigidity, so that it can transmit the rotation angle without loss and transmit high torque.

[0004]

As described above, in the inspection probe using the flexible shaft for the elastic connecting portion, the flexible probe can be inserted following the bent portion of the heat transfer tube by utilizing the elasticity of the flexible shaft. Its torsional rigidity is relatively small. For this reason, when the radius of the bent portion of the inserted tube is reduced and the resistance of the connecting portion is increased, stick slip is caused to cause uneven rotation of the inspection portion, making it difficult to perform an appropriate inspection. Further, in the inspection probe using the gimbal mechanism joint for the connecting portion, it can bend and transmit high torque without loss, but has a small resistance to bending with respect to the longitudinal axis. For this reason, if there is a step on the inner surface of the insertion passage, as in the connection portion between the insertion guide tube 3 and the heat transfer tube 1 as shown in FIG. 5, there arises a problem that the guide short tube is caught. The above-mentioned step on the inner surface is caused by enlarging the inner surface of the exit of the insertion guide tube in order to efficiently align and guide the inspection section at the tip of the inspection probe to the heat transfer tube. Difficult to insert smoothly into the tube. Therefore, according to the present invention, even in the case of a heat transfer tube having a small bending radius, the rotation can be transmitted to the inspection unit without causing rotation unevenness and proper inspection can be performed, and even if a discontinuous portion on the inner surface occurs near the entrance of the heat transfer tube. An object of the present invention is to provide an eddy current inspection probe that can be smoothly inserted without being caught.

[0005]

According to the present invention, there is provided an eddy current inspection probe comprising: a rotary driving unit, an inspection unit, and a rotational driving force from the rotary driving unit; A rotational drive unit having a motor and a slip ring provided in a main body casing, and the inspection unit includes a first alignment member disposed at a front end and a rear end. An eddy current probe rotatably supported between the first alignment members, and a spring biasing the eddy current probe radially outward.
An elastic hollow tube, a plurality of second alignment members rotatably fitted on the outer surface of the elastic hollow tube in the longitudinal direction, and a plurality of second alignment members that sequentially connect the adjacent second alignment members. And a universal joint. When an elastic hose or a helical spring tube having a restoring force is used as the elastic hollow tube, it is preferable to insert a power supply and output signal conducting wire therein. Most of the characteristic effects of the present invention can be obtained by using the elastic rod.

[0006]

Embodiments of the present invention will be described below with reference to the accompanying drawings. First, referring to FIG. 1, an inspection probe 40 of a flaw detector for flaw-detecting a heat transfer tube 1 having a bent portion includes an inspection unit at a distal end, ie, a probe head unit 50, a rotation driving unit, ie, a probe body unit 60 at a proximal end side, and a probe body 60. The probe body 60 is composed of an intermediate elastic connection 70.
Is connected via a flexible tube 41 to a feeding device (not shown) placed outside the heat transfer tube 1. The probe head 50 has a centering member 51 at the front end and the rear end,
Further, a vortex probe 53 is provided at the center, and their detailed structure is shown in FIG. Referring to FIG. 2, for example, a bearing 5 is mounted on a centering member 51 in which an elastic needle-like body is implanted in a ring shape.
5, a casing 57 is supported, and is biased by a compression coil spring 59 in the casing 57 so that the eddy current probe 5
3 are supported. Further, a warhead-shaped guide body 58 is attached to the tip of the casing 57. For this reason, at the entrance of the heat transfer tube 1, the guide body 58 facilitates the entry of the probe head portion 50, and the eddy current probe 53 can rotate while being pressed against the inner surface of the heat transfer tube 1 on the radially outer side. ing. The lead wire 54 extending from the eddy current probe 53 is connected to an external flaw detector as described later.

Referring to FIG. 1 again, a motor 63 is provided on a main body casing 61 of the probe body 60, and a power supply line and a control line extending from the motor 63 become lead wires 65 inside the flexible tube 41. And communicates with a control panel (not shown) placed outside the heat transfer tube 1. Motor 63
A slip ring 67 is attached to the output shaft of the first embodiment to connect the above-mentioned lead wire 54, and the lead wire 54 is combined with a lead wire 65. The elastic connecting portion 70 that communicates with the output shaft of the motor 63 and transmits the rotational force to the probe head portion 50 has a plurality of centering members 71 and a gimbal mechanism joint 73, the detailed structure of which is shown in FIG. Is shown in In FIG. 3, a hollow shaft 75 having both ends connected to a gimbal mechanism joint 73 is provided with a centering member 71 via a bearing 77.
Is fitted. The centering member 71 has an inner cylindrical portion 71a fitted to the bearing 77, and an outer cylindrical finger portion 71c divided in the circumferential direction by a cut 71b in the axial direction, and is entirely made of an elastic material. For this reason, the outer cylindrical finger portion 71c having a mountain-shaped outer surface shape elastically deforms like a cantilever having the center connecting portion 71d as a support end, and performs a centering action. An elastic hose 79 extends through the hollow shaft 75 and the gimbal mechanism joint 73, and the lead wire 54 from the eddy current probe 53 passes through the elastic hose 79. As shown in FIG. 1, the gimbal mechanism joint 73 at the end on the probe body 60 side is connected to the output shaft of the motor 63. Instead of the elastic hose 79, a tubular coil spring having a small helical pitch, for example, approximately equal to the wire diameter may be used. Even in this case, the lead wire 54 is passed through the coil spring.

To perform a flaw detection inspection using the inspection probe 40 having the above-described configuration, the inspection probe 40 is pushed in from the end of the heat transfer tube 1 with the probe head 50 at the head. At this time, the guide body 58 performs a centering operation. Flexible tube 41
When the inspection probe 40 is fed into the heat transfer tube 1 by the feed device, the probe head 5
0 is coaxially held in the heat transfer tube 1 by the core adjusting member 51. If the heat transfer tube 1 has a bent portion as shown in FIG. 1, the elastic connecting portion 70 is deformed following the bent portion. Since the shape and dimensions of the heat transfer tube 1 to be inspected are known from design data such as production drawings, the length of the elastic connecting portion 70 may be estimated in advance. Since the position in the heat transfer tube 1 of the probe head 50 can be determined by the feed amount of the flexible tube 41 or the like, when the position reaches the inspection area, the feed by the feed device and the rotation drive of the motor 63 are combined. In this manner, the rotational displacement of the motor 63 is transmitted to the casing 57 of the probe head 50 by the elastic connecting portion 70, and is rotated around its axis.
That is, the eddy current probe 53 scans the inner surface of the heat transfer tube 1 in a spiral trajectory. At the time of such scanning, an exciting current is sent to the eddy current probe 53 via the lead wire 54, while an eddy current signal is detected and sent to the flaw detector. The flaw detection inspection is performed in this manner. When the deformation of the elastic connecting portion 70 is followed, the outer cylindrical finger portion 71c of the alignment member 71 is deformed in a balanced manner at both ends, so that the hollow shaft 75 and the internal elastic hose 7 are formed.
9 is held at the center of the heat transfer tube 1. Bearing 7 on alignment member 71
Since the hollow shaft 75 supported via 7 is connected to each other by a gimbal mechanism joint 73 which is a universal joint,
The rotation of the motor 67 is transmitted to the casing 57 of the probe head 50 without any loss. A superelastic rod may be used in place of the elastic hose 79 and the coil spring tube of the above-described embodiment, but in that case, the lead wire 54 is appropriately held along the outer surface.

[0009]

As described above, according to the present invention, a gimbal mechanism joint is used as a universal joint at the elastic connecting part connecting the inspection part at the distal end and the rotary driving part at the base end, and the elastic joint is provided at the center thereof. Since the air has passed through the empty tube, the rotation of the rotary drive unit is transmitted to the inspection unit without loss, and the eddy current probe scans the inner surface of the heat transfer tube with a predetermined trajectory, so that appropriate flaw detection inspection can be performed. In addition, since the flexible joint is provided with a bending restoration function by the deformation restoring force of the elastic hollow tube, even if there is a discontinuous portion on the inner surface of the moving passage, it is not caught and the inspection lobe moves smoothly in the heat transfer tube. be able to.

[Brief description of the drawings]

FIG. 1 is an overall structural diagram of an embodiment of the present invention.

FIG. 2 is a partially enlarged sectional view of FIG.

FIG. 3 is an enlarged sectional view of another part of FIG. 1;

FIG. 4 is an overall side view showing an example of a conventional one.

FIG. 5 is a conceptual explanatory view of another conventional apparatus.

[Explanation of symbols]

 Reference Signs List 40 inspection probe 41 flexible tube 50 probe head 51 alignment member 53 eddy current probe 54 lead 55 bearing 57 casing 58 guide 59 compression coil spring 60 probe body 61 main body casing 63 motor 65 lead wire 70 elastic connection portion 71 Aligning member 73 Gimbal mechanism joint 75 Hollow shaft 77 Bearing 79 Elastic hose

Claims (3)

[Claims] 1. A rotary drive unit, an inspection unit, and an elastic connection unit for transmitting a rotational drive force from the rotary drive unit to the inspection unit, wherein the rotary drive unit slips with a motor provided in a main body casing. A first alignment member disposed at a front end portion and a rear end portion; an eddy current probe rotatably supported between the first alignment member; A spring for biasing the probe radially outward, wherein the elastic connecting portion is rotatably fitted to the outer surface of the elastic hollow tube so as to be rotatable and arranged in the longitudinal direction. An eddy current inspection probe comprising: a plurality of second alignment members; and a plurality of universal joints for sequentially connecting adjacent second alignment members. 2. The eddy current inspection probe according to claim 1, wherein the elastic hollow tube is an elastic hose or a helical spring tube. 3. The eddy current inspection probe according to claim 1, wherein a superelastic rod is used instead of the elastic hollow tube.