JPS5910500B2 - Internal flaw detection type magnetic flaw detection device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention relates to an internal surface flaw detection type magnetic flaw detection device for flaw detection on the inner wall surface of a cylindrical pipe.

Generally, this type of flaw detection is performed by exciting a pipe with a magnet to generate an electric current, and using a detector to detect changes in the electric current generated in the pipe. Conventionally, when inspecting the inner wall surface of a cylindrical pipe, a magnet and a detector were placed inside the pipe so as to face the inner wall surface. Although the detector can be made smaller, it is necessary to use a fairly large magnet, which makes it difficult to support and change the magnet inside the pipe, especially for small-diameter pipes, making flaw detection impossible. There was a drawback. The main object of the present invention is to enable easy flaw detection of the inner wall surface of a pipe having a small diameter without any trouble. In this invention, the cylindrical pipe rotates around its axis by the action of support rollers and the like. The magnet is arranged to face the outer peripheral surface of the pipe and is connected to a magnet truck that moves parallel to the axis of the pipe. The detector is disposed inside the pipe so as to face the inner wall surface thereof, and is attached to an inner rod extending axially inside the pipe. The inner rod is connected to an inner rod carriage that moves parallel to the axis of the pipe outside the pipe. Further, the inner rod is provided with a guide roller that engages with the inner wall surface of the pipe. The magnet truck and the inner rod truck are connected via a connecting rod. The magnet and detector are displaced parallel to the loop along the outer circumferential surface and inner wall surface of the pipe, and the entire inner wall surface of the pipe is detected in a spiral manner. Embodiments of the present invention will be described below with reference to the drawings. In the figure, a cylindrical pipe P to be inspected for flaws is supported between the outer peripheral surfaces of a pair of support rollers 1.

A pair of magnets M for exciting a pipe P are arranged above the pipe P and connected to a magnet truck 3 via a cylinder 2.

The height of the magnet M can be arbitrarily adjusted by the cylinder 2, so even if the diameter of the pipe P is different, the magnet M can be easily opposed to the outer peripheral surface of the pipe P as shown in the figure. can. The magnetic truck 3 is supported by rails 5 via rolling rollers 4. The rail 5 extends parallel to the axial center of the pipe P, and the magnet M can be displaced along the outer circumferential surface of the pipe P in parallel to the axial center together with the magnet truck 3. Detector D detects changes in the current flowing through pipe P.
It is provided at a certain location on the upper end of the inner rod 6 that extends in the axial direction inside the rod. The inner rod 6 is connected to an inner rod truck 8 via a pair of cylinders 7 on the outside of the end surface of the pipe P. The height of the inner rod 6 can be arbitrarily adjusted by the cylinder 7, and as shown in the figure, the upper end of the inner rod 6, and therefore the detector D, can be placed at the upper end of the inner wall surface of pipes P of various diameters. Can be made to face each other. The inner rod truck 8 is supported by a rail 10 via rolling rollers 9. The rail 10 extends parallel to the axis of the pipe P below the rail 5 of the magnetic truck 3. Further, the position of the detector D of the interpolation rod 6 is set corresponding to the position of the magnet M, and the magnet cart 3 and the interpolation rod cart 8 are connected via a connecting rod 11. Therefore, the detector D of the inner rod 6 can be displaced in parallel to the axis along the inner wall surface of the pipe P integrally with the inner rod carriage 8, and the magnet M follows the detector D. Displaced parallel to the axis. Furthermore, a guide roller 12 that engages with the inner wall surface of the pipe P is provided at the tip of the inner rod 6. Further, between the end face of the pipe P and the inner rod carriage 8, a receiving roller 13 that supports the inner rod 6 so as to be freely displaceable parallel to the axis.
is provided. The height of the receiving roller 13 is configured to be freely adjustable by the action of a cylinder or the like. In the internal surface flaw detection type magnetic flaw detector constructed as described above, the pipe P is excited by the magnet M, and a current is generated.

If the pipe P has a flaw, the current flowing through the pipe P changes at that location, causing eddy currents and the like. The detector detects a change in the current on the inner wall surface of the pipe P, and thereby the inner wall surface is inspected for flaws. The support roller 1 of the four pipes P rotates around its axis, and the pipe P rotates in accordance with the rotation of the support roller 1.

In addition, the magnet truck 3 and the inner rod truck 8 are sent along the rails 5 and 10 at a constant speed, and the detector D of the inner rod 6 is displaced parallel to the axis along the inner wall surface of the pipe P. , the magnet M follows the detector D and is displaced along the outer peripheral surface of the pipe P in parallel to the axis. Therefore, the entire inner wall surface of the pipe P is scanned in a spiral manner by the detector D to detect flaws.
The height of the inner rod 6 is kept constant by a receiving roller 13, and the guide roller 12 of the inner rod 6 adjusts the positional relationship between the inner wall surface of the pipe P, the tip of the inner rod 6, and the detector D. It functions to hold the As is clear from the above embodiments, this invention has the following features:
The magnet that excites the pipe is placed outside the pipe facing its outer circumferential surface, and the detector is placed inside the pipe facing its inner wall, making it difficult to insert the magnet inside the pipe due to its small diameter. Even pipes can be easily inspected for flaws on their inner wall surfaces without any hindrance.

Also, by rotating a cylindrical pipe around its axis,
Since the magnet and detector are displaced parallel to the axis of the pipe, it is possible to detect flaws over the entire inner wall surface of the pipe in a spiral manner. The magnet is connected to a magnetic cart,
Since the interpolation rod with the detector attached is connected to the interpolation rod cart, and both carts are connected via the connecting rod, the detector and magnet can be made to follow each other to ensure displacement parallel to the axis of the pipe. I can do it. Furthermore, since the inner rod is provided with a guide roller that engages with the inner wall surface of the pipe, the inner wall surface of the pipe and the inner rod are
The positional relationship of the detectors can be maintained appropriately.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing one embodiment of the present invention, Fig. 2 is a front view showing the magnet and magnet truck shown in Fig. 1, and Fig. 3 shows the interpolation rod and interpolation rod cart shown in Fig. It is a front view. P... Pipe, 1... Pipe support roller, M... Magnet, 3... Magnet truck,
D...Detector, 6...Interpolation rod, 8...
...Interpolation rod truck, 11...Connection rod, 12.
...Guide roller.

Claims (1)

[Claims] 1 A mechanism for rotating a cylindrical pipe around its axis, a magnet that excites the pipe to generate an electric current, arranged opposite to the outer peripheral surface of the pipe, A detector connected to a magnetic cart moving in parallel and detecting changes in the current flowing through the pipe is disposed inside the pipe so as to face the inner wall surface thereof, and is inserted into the pipe and extends in the axial direction thereof. The inner rod is attached to a rod, and the inner rod is connected to an inner rod carriage that moves parallel to the axis of the pipe on the outside of the pipe, and the inner rod has a guide roller that engages with the inner wall surface of the pipe. Further, the magnet truck and the inner rod truck are connected via a connecting rod, and the magnet and the detector are displaced parallel to the axis along the outer circumferential surface and the inner wall surface of the pipe, An internal surface flaw detection type magnetic flaw detection device characterized by being designed to detect flaws on a wall surface.