JPH03282361A - Rotary type cross-wound probe - Google Patents

Abstract

PURPOSE:To facilitate flaw detection over the entire periphery without making an intersection operate as a blind point although a couple of coils has the intersection by enabling a probe head to rotate on its axis. CONSTITUTION:The probe head 5 is wound with the couple of coils 8, which cross each other at least two positions on the peripheral flank of the head 5 to change in front-rear position relation. This coils 8 are coupled with signal lines provided in a flexible tube 2 so as to excite the coils 8 and detect the a flaw detection signal regardless of the rotation of the head 5. Further, a coil centering bush 6 is fitted atop of the head 5 so that the brush is movable at a specific conic angle to the axis of the head 5 and unrotatable independently of the rotation of the head 5. Then when the head 5 rotates on its axis, the intersection of the coils 8 on the head 5 also rotates and a blind point due to the intersection of the coils is relatively absent, so that a flaw in a heat conduction tube is accurately detected.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a rotary crosswound probe, and more particularly to a rotary crosswound probe that can easily and accurately detect defects in a pipe.

[Prior art and problems to be solved by the invention] As is well known, in a steam generator for a pressurized wooden nuclear reactor, a large number of inverted U-shaped heat transfer tubes (22 mm in outer diameter) are installed inside a vertical cylindrical tube. , wall thickness: 1 mm, height: 5 m) is placed upright on the bottom end plate, and the bottom of the end plate is vertically partitioned into two parts, one of which is an inlet chamber and the other is an outlet chamber. The cylindrical tube is filled with secondary coolant, and the high-temperature, high-pressure primary coolant inside the reactor is taken in from the inlet, passed through each heat transfer tube, and returned to the reactor from the outlet. The coolant is allowed to evaporate.

However, if the heat exchanger tubes corrode or crack due to long-term use, the primary coolant, which has strong radioactivity, may leak, so the condition of the inner surface of the heat exchanger tubes must be periodically inspected using a probe. That's what I do.

As such a probe, as shown in FIG. 3, a pair of coils 11 are wound around a cylindrical body made of synthetic resin at the tip of a flexible vibe 10, and supported at the center of the tube by centering members 12 at the front and rear thereof. There is a bobbin type probe in which a bobbin type probe head and a conical guide element 13 are sequentially attached. This bobbin type probe is inserted into the heat exchanger tube 14, which is a probe head, while applying an alternating current to the coil 11, and moves forward or backward, and the coil 11 induces an eddy current in the heat exchanger tube. If there is a flaw in the heat exchanger tube 14, the flaw will cause a disturbance in the eddy current. This bobbin type probe is configured to externally detect the state in which the current in the coil 11 changes due to the disturbance.

However, this bobbin-type probe senses a large signal from the tube support plate that supports the heat transfer tube, making it difficult to detect defects. Therefore, as a probe to eliminate such drawbacks, a loss-wound type probe 2 as shown in Fig. 4 is proposed.
1 has been developed. This cross-wound probe 2
1, as shown in FIG. 4, has a structure in which a pair of coils 28 wound around a probe 25 cross each other at two locations, and the positions thereof are exchanged back and forth. This cross-wound type probe 21 does not sense the signal from the part where the tube support plate is attached because the tube support plate attached to the heat exchanger tube cancels out the signal from the entire circumference in that part. If a part is damaged when mounted on a board, mounting on a tube support plate will eliminate interference signals caused by the part.
It is possible to accurately detect signals based on the scratches. However, this cross-wound probe has serious drawbacks such as first order.

That is, if the crossing point of the coil wound around the crosswound probe becomes a dead point, and if the flaw in the heat transfer tube happens to coincide with the dead point of the coil, the flaw in the heat transfer tube cannot be detected.

The present invention has been made to solve the above-mentioned drawbacks.

That is, an object of the present invention is to provide a cross-wound probe without dead points.

[Means for Solving the Problems] The present invention for solving the problems described above is a cross-wound probe equipped with a probe head that is provided at the tip of a flexible tube and has coils that intersect. This is a rotating cross-wound probe that is rotatable around the heart.

[Operation] In the rotary cross-wound probe of the present invention, a pair of coils are wound around the circumferential side of the probe head, and the pair of coils intersect at least two places on the circumferential side.

As the probe head rotates about the axis, the intersection of the coils in the probe head also rotates, and there is no relative dead point based on the intersection of the coils. Therefore, flaw detection failure due to dead points, which is the case with conventional cross-wound probes, is eliminated.

[Example] Next, the present invention will be described in more detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing an example of a rotary crosswound probe of the present invention.

As shown in FIG. 1, a rotary crosswound probe 1, which is an embodiment of the present invention, has a driving means such as a motor 3, a first coil centering brush 4, and a probe head 5 at the tip of a flexible tube 2. , a second coil centering brush 6, and a guide element 7 are connected in this order.

More specifically, this rotary cross-wound probe l has a motor 3 fixed to the tip of the flexible tube 2. A first coil centering brush 4 is fixed to the tip of the motor 3 so as to be movable at a predetermined cone angle with respect to the axis of the motor 3.

Further, the first coil centering brush 4 is penetrated so that it can be rotated independently of the rotating shaft of the motor 3 or the rotating shaft. A probe head 5 is attached to the tip of the first coil centering brush 4 so as to be movable at a predetermined cone angle with respect to the axis of the first coil centering brush 4, and furthermore, a probe head 5 is attached to the tip of the first coil centering brush 4. Rotatably coupled by rotation.

A pair of coils 8 are wound around the probe head 5, and the pair of coils 8 intersect at at least two places on the circumferential surface of the probe head 5, so that the front and rear positions thereof are exchanged. The pair of coils 8 are arranged in the flexible tube 2 via sliding contacts, for example, so that the coil 8 can be excited and the flaw detection signal can be detected despite the rotation of the probe head 5. connected to a line.

A second coil centering brush 6 is attached to the tip of the probe head 5 and is movable at a predetermined conical angle with respect to the axis of the probe head 5 and is attached so as not to rotate independently of the rotation of the probe head 5. A guide element 7 is attached to the tip of the second coil centering brush 6.

The rotary crosswound probe 1 having such a structure is
For example, it is inserted into a heat exchanger tube with the guide element 7 at the beginning. A motor 3 provided at the tip of the flexible tube 2 has a first coil centering brush 4, a probe head 5, a second coil centering brush 6, and a guide element 7 each movable at a predetermined cone angle. Since the rotary cross-wound probe l is installed, the rotary cross-wound probe l can be smoothly inserted even into a curved heat exchanger tube. the first coil centering brush 4 and the second coil centering brush 4;
The coil centering brush 6 achieves alignment of the probe head 5 so that the central axis of the probe head 5 coincides with the central axis of the heat transfer tube. On the other hand, a current is supplied to the coil 8 via a signal line (not shown), and the coil 8 is excited. This generates eddy currents in the heat exchanger tubes. If a flaw exists in the heat transfer tube, this eddy current is disturbed, the coil 8 is sensitive to the flaw, and a flaw detection signal is outputted via the signal line. The probe head 5 is rotated about its axis by the motor 3. Therefore, the intersection point of the coil 8 formed on the circumferential side of the probe head 5 also rotates, and as a result, a state in which there is relatively no dead point is achieved. Therefore, flaws existing in the heat exchanger tube can be detected accurately.

Furthermore, since the pair of coils 8 in the probe head 5 intersect, even if the heat exchanger tube has a tube support plate portion, it is possible to accurately detect flaws in the heat exchanger tube at the tube support plate portion.

An embodiment of the present invention has been described above.

It goes without saying that the invention can be modified and implemented as appropriate within the scope of the gist of the invention.

For example, as shown in FIG. 2, the rotation of the probe head 5 is controlled not by the motor 3 provided at the tip of the flexible tube 2, but by the motor 3 provided at the rear end of the flexible tube 2 and its rotation shaft. This may be done through the connected flexible joint 9. In this case, the tip portion of the flexible tube 2 can be made smaller.

[Effects of the Invention] As detailed above, according to the present invention, even though at least one pair of coils provided in the probe head have an intersection, there is no interaction with the intersection point or blind point. Therefore, it is possible to provide a rotary cross-wound probe capable of detecting flaws around the entire circumference of the probe head.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention, Fig. 2 is an explanatory diagram showing another embodiment of the invention, Fig. 3 is an explanatory diagram showing a conventional bobbin type probe, and Fig. 4 is an explanatory diagram showing a conventional bobbin type probe. FIG. 2 is an explanatory diagram showing a so-called crosswound type probe. 1...Crosswound probe, 2...Flexible tube, 5...Probe head, 8...Coil.

Claims (1)

[Claims] (1) A crosswound probe equipped with a probe head provided at the tip of a flexible tube and having intersecting coils, the rotary cross being characterized in that the probe head is rotatable around its axis. Wound probe.