JPS629964B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a metal-coated filament,
In particular, the present invention relates to a manufacturing method that eliminates the influence of welding heat on the filament during welding of metal pipe joints.

Composite cables, which integrate metal-coated wire bodies such as optical fibers housed in metal pipes with overhead ground wires or submarine power lines, are promising as future cables because they can perform both power transmission and communication with a single cable. It has become a thing.

By the way, the striated bodies such as optical fibers housed in the metal pipe are made of polyamide resin (product name: nylon, hereinafter referred to as nylon), polypropylene, polytetrafluoroethylene resin (product name: Teflon, hereinafter referred to as nylon), polypropylene, polytetrafluoroethylene resin (product name: Teflon, hereinafter referred to as nylon), Generally, a coating layer of plastic resin such as
If the temperature reaches around 200°C, the above-mentioned coating layer will be softened since the heat resistance limit of plastic resin is about 200°C.

For this reason, when welding the joints of metal pipes after pipe making, the welding heat that travels through the pipe is conducted to the filament bodies, which increases the temperature of the filament bodies, which causes the coating layer to There was a disadvantage that part or most of it melted and was fused into the metal pipe.

In particular, when the material of the metal pipe is aluminum, copper, etc., which have good thermal conductivity, and the diameter of the pipe is as small as 8 mm, the influence of welding heat is large, and the coating layer is continuous. There was a situation where the metal melted.

The present invention attempts to solve the above problem by cooling the metal pipe so that the temperature rise of the filament is below a predetermined value during welding. To explain, in FIG. 1, 1 is a metal pipe formed by pipe-forming means, for example, roll forming, 2 is a filament such as an optical fiber housed in the pipe 1, and 3 is a metal pipe formed by roll forming.
is a joint of the metal pipe 1, 4 is a welding coil provided on the outer periphery of the metal pipe 1, and as shown in the figure, the metal pipe 1 in which the filament 2 is housed
After the seam 3 is heated by the welding coil 4, it is fed between a pair of squeeze rolls 5a, 5b, and the seam 3 is pressed together by both rolls 5a, 5b.

The location where the pressure contact force is maximum is at both rolls 5a, 5.
This is the welding point S located on the line connecting the shortest distance of b, and therefore welding is performed at this point S, and the seam 3 is sewn by the continuity of the welding points S.

By the way, what is important for the present invention is that the seam 3 is closed so that the temperature rise of the striatum 2 is below a predetermined value.
This is to cool the metal pipe 1 during welding.

As a cooling means, gas or the like may be directly sprayed onto the contact portion between the filament 2 and the metal pipe 1, but it is preferable to immerse the metal pipe 1 in a cooling liquid 6 as shown in FIG.

To explain this further with reference to the figure, the filament 2, such as an optical fiber, consisting of a core wire 7 and a coating layer 8 formed on the outside thereof, is usually placed at a position opposite to the seam 3, that is, at a position opposite to the seam 3. If the joint 3 is placed at the top, it will be housed at the bottom of the metal pipe 1, so in order to prevent the temperature of the coating layer 8 from rising due to conduction heat from the pipe 1, the bottom of the pipe 1 will not be cooled. Therefore, the bottom side of the metal pipe 1 is immersed in the cooling liquid 6 as shown in FIG.

Of course, the cooling location is not limited to the above, and may be any location on the metal pipe 1 as long as the temperature rise of the filament body 2 is suppressed to a predetermined value or less.

A more specific example is given below.

Specific example [] When sewing the seam 3 of an aluminum metal pipe 1 with an outer diameter of 8 mm and a thickness of 1.2 mm by high-frequency TIG welding, water is used as the cooling fluid 6 and the water temperature is maintained at 80°C or less. In addition, when an optical fiber coated with Teflon was used as the filament 2, no effect of welding heat on Teflon was observed.
Even after metal coating, the transmission characteristics of the optical fiber did not change at all.

Specific example [] When sewing the joints 3 of stainless steel metal pipes 1 with an outer diameter of 6 mm and a thickness of 0.5 mm by TIG welding, alkyl diphenyl-based synthetic oil or alkylnaphthalene-based synthetic oil is used as the cooling fluid 6. At the same time, when an optical fiber coated with nylon, which has a lower heat resistance limit than Teflon, was used as the filament 2, no effect on the nylon coating layer was observed as in Example [].

The reason for using nylon is that the thermal conductivity of stainless steel is about 1/10 that of aluminum.

In addition, in FIG. 1, 9 is a power source that supplies power to the welding coil 4.

As explained above, the present invention provides a method for manufacturing a metal coated filament by welding the joints of the metal pipe after the filament is housed and pipe-formed. striae,
The metal pipe is held in a position facing the joint of the metal pipe, and during welding, at least the contact area between the filament and the metal pipe is cooled with a cooling fluid to reduce the temperature rise of the filament to a predetermined level. It is characterized in that it is suppressed to below a value.

Therefore, in the case of the method of the present invention, when welding a joint after pipe making, the welding heat conducted through the metal pipe to the filament is set to be below the heat resistance limit of the filament. It can prevent the body from softening or melting.

[Brief explanation of the drawing]

1 and 2 are explanatory views of the manufacturing method according to the present invention. 1...metal pipe, 2...striate body, 3...seam.

Claims (1)

[Claims] 1. In a method of manufacturing a metal-coated filament by welding the joints of a metal pipe after the filament is housed and pipe-formed, the filament in the metal pipe is removed from the metal pipe. It is held in a position facing the seam, and during welding, at least the contact area between these filament bodies and the metal pipe is cooled with a cooling fluid to suppress the temperature rise of the filament body to below a predetermined value. A method for producing a metal-coated filament, characterized by: