JPH0219689B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a device for inserting a deep flaw cable for flaw detection in a tube body, and more particularly to a cable insertion device for preventing twisting when a cable with a float is inserted into and fed into a tube to be flaw-detected.

Heat exchangers used in nuclear reactors have heat transfer tubes bent into complicated shapes to improve heat transfer efficiency, and many of them are multilayer helical coils in particular. In this case, if the heat transfer tube is damaged and the internal fluid comes into contact with the heat transfer medium, a serious accident may occur.
In particular, when the fluid in the heat transfer tube is water and the heat transfer medium is sodium, if they come into contact, they will react explosively, and there is a risk of catastrophic accidents such as destruction of the heat exchanger. For this reason, it is necessary to regularly inspect deep flaws in heat exchanger tubes, but flaw detection from the outside of the heat exchanger tubes is not always sufficient, and there is a demand for flaw detection from the inner surface of the heat exchanger tubes. The inventors have developed and put into practical use a flaw detection cable in which a flaw detection device is attached to the tip of the cable and floats are attached at equal intervals for flaw detection from the inner surface of a heat transfer tube.

FIG. 1 shows this cable insertion device for flaw detection.

In the figure, water W is injected and filled into the main body 26 of the apparatus, and a flaw detection cable 25 wound around a drum 22 is sent out by rotating a handle 23. The sent-out cable 25 enters the heat exchanger tube 27 to be inspected from the nozzle 28 along the flow of water inside the device, moves forward with the flow of water,
Flaw detection is performed from the inner surface of the tube using a flaw detection device (not shown) attached to the tip. In the case of this device, if the rotation speed of the handle 23 is too fast, the cable 25 will become slack, and the cable will float up inside the device due to the buoyancy of the float 29, and in severe cases, it will get tangled in the device and become impossible to send out. . In this case, the repair must be carried out by removing the bolts 38, removing the top cover 21, and draining the water inside the device, which is inconvenient to handle.

Further, as the cable progresses through the tube to be inspected, it becomes twisted, and especially in the case of a helical coil, the cable twists once as the cable moves through one turn of the coil. Since the device shown in FIG. 1 does not have a mechanism for removing twists, the cable twists increase as the cable advances, making it impossible for the cable to advance or even causing accidents such as cable breakage.

SUMMARY OF THE INVENTION An object of the present invention is to provide a cable insertion device that eliminates the above-mentioned problems, allows the cable to be checked in its unwound state, and also allows the cable to be untwisted.

In short, the present invention provides a cable insertion device having a sprocket that engages with a float of a flaw detection cable, and a cable feeding tube that has a cable passage in the center and feeds the flaw detection cable using pressurized water supply. An upper plate is provided that can be rotated around the axis of the cable feed pipe in a direction to untwist the cable according to the amount of twist of the cable, and a sprocket for guiding the flaw detection cable to the cable feed pipe is mounted on the upper plate. This is a cable insertion device that prevents twisting of cables, and is characterized in that the cables are connected vertically.

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

In FIGS. 2 and 3, reference numeral 1 denotes a main body of the cable insertion device, and the upper part of the main body 1 is a flange portion 1a, and an upper plate 30 is placed on this flange portion 1a. FIG. 3 shows details of the state in which the upper plate is placed. Reference numeral 31 denotes a ball bearing interposed between the upper plate 30 and the flange portion 1a, which allows the upper plate 30 to rotate around the center line 32 of the downward movement of the cable 25 descending the main body 1. A main sprocket 5a is provided on a support 33 erected on the upper plate 30, and its base is supported by a spring 6. 5b is a support 3 which similarly has a spring at its base.
This is a sub-sprocket attached to the main sprocket 5a, which faces the main sprocket 5a, and is arranged so that the center of the gap between the outer circumferential surfaces is located at the axis of the pair of main parts of the device. Recesses 5a' and 5b' are formed in each sprocket 5a and 5b, respectively, so that each float 2 of the cable 25 to be fed can be
9 engages with this recess and prevents the cable 25 from advancing freely due to the water pressure of water supply, which will be described later.
34 is a handle for rotating the upper plate.

Reference numeral 2 denotes a cable feed pipe disposed within the main body 1 of the apparatus, and a water supply injection part 7 is formed at the lower part of the cable feed pipe 2. A ring-shaped water supply distribution passage 7a is formed in the water supply injection part 7, and a plurality of water supply injection passages 7b branch from this water supply distribution passage 7a, and the cable passages are arranged so as to inject the supply water in the traveling direction of the cable 25. It opens at 2a.

The operating state of the above device is shown below.

First, when inserting the cable 25 into the pipe body to be inspected, pressurized water W is supplied from the water supply nozzle 4. The water supply W is violently injected into the cable passage 2a in the cable traveling direction through the water supply distribution passage 7a and the water supply injection passage 7b. The cable 25 moves forward along the flow of this water supply. In this case, each float 29 of the cable 25 is held between the main sprocket 5a and the sub sprocket 5b, so the cable does not move forward automatically due to the water flow, and the speed of movement of the cable 25 can be adjusted by adjusting the rotation of each sprocket. can. Further, in this case, the tensile force of the cable 25 is absorbed by the spring 6, so there is no risk of the cable being cut.

Next, when the cable 25 is twisted, the upper plate 30 is rotated by the handle 34 in a direction corresponding to the amount of twist in which the cable 25 is untwisted. As a result, the main sprocket 5a and the sub-sprocket 5b rotate around the descending cable 25, thereby removing the twist in the cable 25. In this way, the cable 25 is moved forward while untwisting it, and the pipe body is inspected for flaws.

As the water supply W is supplied, a part of the supply water flows backward, rises inside the cable passage 2a, and overflows into the insertion device main body 1, but the overflowed supply water is discharged to the outside from the discharge port 35.

Next, when pulling back the cable 25, the supply of water W is stopped, the sprockets 5a and 5b are rotated in the opposite direction, and the cable is pulled back.

By carrying out this invention, the reliability of the device is greatly improved because the cable is able to be checked as to how it is being fed out, and since the cable can be untwisted, there is no need to worry about accidents such as wire breakage.

[Brief explanation of drawings]

FIG. 1 is a sectional view of a conventional flaw detection cable insertion device, FIG. 2 is a sectional view of a flaw detection cable insertion device according to the present invention, and FIG. 3 is an enlarged partial view of FIG. 2. 1... Insertion device main body, 2... Cable feeding pipe,
2a...Cable passage, 5a...Main sprocket, 5b...Sub-sprocket, 25...Flaw detection cable, 29...Float, 30...Top plate, 32
...The center line of descent of the cable.

Claims (1)

[Claims] 1. In a cable insertion device having a sprocket that engages with a float of a flaw detection cable, and a cable feed pipe that has a cable passage in the center and feeds the flaw detection cable using pressurized water supply, the cable feed pipe An upper plate is provided that is rotatable around the axis of the cable in a direction to untwist it in accordance with the amount of twist of the cable, and a sprocket for guiding the flaw detection cable to the cable feed pipe is mounted and connected to the upper plate. A cable insertion device that prevents cable twisting.