JPS62263892A - Cleaning method for weld defective part of metallic pipe - Google Patents

Abstract

PURPOSE:To thoroughly remove the foreign matter intruding into the weld defective part of a metallic pipe by putting the weld defective part into an ultrasonic cleaning tank and ultrasonically cleaning said part. CONSTITUTION:An Al pipe 2a having a pinhole 3 which is the weld defective part is held in place between the cleaning tank 1a and a cover 5a via a sealing part 4 and thereafter, a cleaning liquid 9 is put from a piping 7 for the cleaning liquid into the cleaning tank 1a and a pressure is exerted from the outside to the Al pipe 2a by a pressure piping 6. An ultrasonic oscillator is driven and the Al pipe is ultrasonically cleaned by a bonded type oscillator 8a. Gaseous N2 is passed in the metallic pipe after the cleaning to evaporate the freon intruding into the pipe. The pinhole is then repaired by laser welding and the defectless weld zone is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for cleaning a weld defective part of a metal pipe, and can be used as the n2 process when repairing the weld defect part.

[Conventional technology]

Optical fiber, communication/electric cable, etc. AQ% Cu,
These protective tubes are installed by being inserted into stainless steel pipes, etc., but since these protective tubes require long tubes with no uneven thickness, the strips are bent and formed into a tube shape, and the butt parts are TIG welded. Welding methods such as gas welding are generally used.

For example, an optical fiber-containing metal tube unit for an overhead ground wire used as an OPCW (power-optical composite cable) has an outer diameter lI ~ 6 mm and a wall thickness α5 ~ 0.6 mm, as shown in Figure 5.
It has a structure in which a shiny eyebar core wire 10 is housed in a ranOAA pipe 2a, and after continuous production for 1 to 5 km, other Al wires are twisted around the outer periphery to produce a final product.

The process of forming a metal tape as shown in Figure 4, storing the optical fibers in the metal tube one after another during the forming process, welding the butt portions, reducing the diameter to increase the strength of the metal tube, and then winding it up. It is manufactured by. During diameter reduction in this process, lubricating oil is generally used to reduce the frictional force that acts between the AP or pipe and the roll or die.

[Problem that the invention seeks to solve]

When manufacturing the metal tube mentioned above, the arc from the electrode becomes unstable and welding defects such as pinholes 5 may occur in the welded part 11 as shown in Figure 5. Lubricating oil has penetrated into the defect, and this oil cannot be removed simply by cleaning the surface of the pipe 2a, so even if you try to repair this part by TIG welding, laser welding, etc., the lubricating oil will evaporate during welding, A healthy weld:
It was difficult to do so.

[Failure to solve the problem]

The present invention was obtained as a result of intensive research in order to solve these problems, and involves placing the welded defective part of the metal pipe in an ultrasonic cleaning tank and cleaning the welded defective part with ultrasonic waves. A method for cleaning a welding defect in a metal pipe, characterized by:

[For production]

In the present invention, by placing the weld defect in an ultrasonic cleaning tank and cleaning it with ultrasonic waves, it is possible to completely remove the lubricating oil that has soaked into pinholes, etc., and the weld can be restored to a healthy weld by re-welding. can be obtained.

The ultrasonic oscillator has an output of 600W and a frequency of 10 to 20 KH.
A liquid of about
When using a bonded vibrator as shown in FIG. 1, it is desirable to apply pressure from the outside of the tube or to reduce the pressure inside the tube. In other words, the pinholes that occur in welds generally have a narrow, winding shape; for example, in the M-pipe weld mentioned above, they are usually about 10 μm in diameter, 2 to 5 ttan in length, and have a depth that matches the wall thickness of the tube. A pinhole is formed, and impurities such as oil that have entered the pinhole can be more effectively removed by applying or reducing pressure. In other words, by applying pressure from the outside of the tube or reducing the pressure inside the tube, the cleaning liquid enters the metal tube through the weld, thereby cleaning the oil in the pinhole. Pressure force is 1
~3 to 9/cJ (gauge pressure), 10 for reduced pressure
mn ) Ig (P vs. pressure) or so, and a few minutes of washing time is sufficient.

5 yuan? (Trichlene, etc. is generally used as the 4" liquid, but in the optical fiber-containing Al tube described above,
It is desirable to use CFCs that do not melt the plastic coating layer of the optical fiber.

〔Example〕

Next, an embodiment of the present invention will be described in detail with reference to the drawings. As shown in FIG. After cleaning all 2a, pour the cleaning liquid 9 into the cleaning tank 1 from the cleaning liquid piping 7, and use the pressure piping 6 to remove the AI.
! 2 K9/c, i (gauge pressure) from the outside to the pipe 2a
pressure was applied. In addition, the cleaning tank is made of stainless steel, and the cleaning tank is made of stainless steel.
It was cooled with a condenser (not shown) so that the temperature was below .degree. In this state, an ultrasonic oscillator with an output of 6 OOW and a frequency of 15 KHz was operated to perform ultrasonic cleaning for 5 minutes using the adhesive type vibrator 8a. After cleaning, N gas was flowed into the metal tube to evaporate the Freon that had entered the tube, and the pinhole was repaired using an F4m laser, resulting in a sound weld. On the other hand, when trying to perform laser welding after cleaning only the surface of the pipe with Freon as in the conventional method, the lubricating oil burns and smoke is generated, and the re-welded part does not come into close contact with the previously welded part, resulting in a sound welded part. I couldn't do it.

- AQ having pinhole 5 in the same manner as in the embodiment described in
After setting the tube 2a in the cleaning tank 1a shown in FIG. 1, seal one end of the tube and connect the other end to a vacuum pump.
The pressure inside the tank was reduced to 10105H. (Pressure was not applied from the outside of the pipe.) In this state, after ultrasonic cleaning was performed in the same manner as in the above example, the pinhole was repaired by laser welding, and a sound weld was obtained. done.

Furthermore, as shown in FIG.
After inserting the pipe 2b, the cleaning liquid pipe 7 is connected to the washing a) tank 1b.
Add cleaning solution 9 to the inside. Ultrasonic cleaning was performed for 5 minutes using Tri-Clean as a cleaning solution, driving an ultrasonic oscillator with an output of 600 W and a frequency of 20 KHz, and an immersion type vibrator 8b. After cleaning, the pinhole was repaired by TIG welding, and a sound weld was obtained.

On the other hand, when trying to perform TIG welding after cleaning only the surface of the pipe with WotriClean as in the conventional method, the lubricating oil burns and smoke is generated, and the re-welded part does not come into close contact with the previously welded part, resulting in a sound welded part. I couldn't do it.

〔Effect of the invention〕

In the present invention, the welded defective part of the metal pipe is placed in an ultrasonic cleaning tank and the welded defective part is cleaned by ultrasonic waves.
It becomes possible to completely remove foreign substances such as lubricating oil that have penetrated into weld defects such as pinholes, and a healthy weld can be obtained by rewelding.

[Brief explanation of drawings]

FIGS. 1 and 2 are cross-sectional views showing different configurations of ultrasonic cleaning tanks used in the practice of the present invention, and FIG. 2 is a cross-sectional view showing the structure of a metal tube unit containing original fibers. FIG. 4 is a manufacturing process diagram of the optical fiber-containing metal tube unit. 1a...Cleaning tank, 1b...Cleaning tank, 2a...M tube, 2b...ctz#, s...Pinhole, 4...
Seal portion, 5a...cover, 5b...cover, 6.
...Pressure piping, 7.. Cleaning liquid piping, 8a.. Ultrasonic vibrator, 8b.. Ultrasonic vibrator, 9.. Cleaning liquid,
1o...Optical fiber, 11...Welding part. Applicant: Furukawa Electric Co., Ltd. '1 Figure 2 Figure 3 Figure 4

Claims (3)

[Claims] (1) A method for cleaning a weld defective part of a metal pipe, which comprises placing the weld defective part of the metal pipe in an ultrasonic cleaning tank and cleaning the weld defect part with ultrasonic waves. (2) In the method for cleaning a weld defective portion of a metal tube as set forth in claim 1, the ultrasonic cleaning tank has an airtight structure and pressure is applied to the metal tube from the outside of the metal tube. (3) In the method for cleaning a welding defective portion of a metal tube as set forth in claim 1, the pressure inside the metal tube is reduced.