JPH0557044B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing a thin metal tube containing a filament.

(Prior art) The production of thin metal tubes containing filaments is usually performed by forming a metal tape using a roll forming method or a die forming method, and then sequentially inserting plastic-covered metal wires or optical fiber cores into the tape. Accommodating the filament and sequentially welding the seams of the metal tape to form the metal small diameter tube body, and in order to achieve the desired outer diameter, use a diameter reduction die to reduce the metal narrow diameter tube body by approximately 10%. The diameter is reduced to obtain a thin metal tube containing a filament of the required outer diameter. The final outer diameter of the metal small diameter tube body manufactured in this way is usually 8 mmφ or more,
Although pinholes caused by poor welding have been a problem, the tensile strength of the small diameter metal tube body has never been a problem.

However, in recent years, optical fiber composite overhead ground wires have been attracting attention for use as information transmission means by accommodating optical fiber core wires in the overhead ground wires in order to prevent lightning strikes. Various structures are conceivable for this optical fiber composite overhead ground wire, but the most likely basic structure is one in which a thin metal tube containing an optical fiber is placed in the center and aluminum wires are twisted around it. At this time, the tensile strength of the small diameter metal tube body made of the central aluminum tube is better to be large in order to protect the internal optical fiber core from external forces, and a tensile strength of 16 kg/mm ² or more is required by equipment standards. The diameter is required to be 4 to 5 mmφ. In order to produce such tensile strength, it is necessary to work harden the small diameter metal tube body. However, in the case of small-diameter metal tube bodies made of pure aluminum, the tensile strength after welding decreases to 10 kg/mm ² or less due to welding heat, so a large drawing process is required to produce a tensile strength of 16 kg/mm ² or more. ing. FIG. 1 shows data on the tensile strength of a small diameter aluminum tube body, with the area reduction ratio plotted on the horizontal axis and the tensile strength plotted on the vertical axis. The base material is a 10mm aluminum small diameter tube body just after welding.
φ, material AIl050 was used. From this data, in order to obtain a tensile strength of 16 kg/mm ² or more, the area reduction rate must be 50% or more. Normally, a diameter reducing die is used to reduce the area, but when drawing a small diameter aluminum tube body, a single diameter reducing die can only reduce the area by about 15%.
If an attempt is made to reduce the area further, the small diameter aluminum tube body will break. In order to reduce the area by 50% or more using diameter-reducing dies, it is necessary to arrange the diameter-reducing dies in three or more stages, and to install a pulling machine after each diameter-reducing die. However, the disadvantage is that the line length is long and the equipment cost is high.

There is also a method of sequentially reducing the area of the metal small-diameter tube body using rolling rolls, but in this case, it is necessary to control the speed of each rolling roll, which has the disadvantage of increasing equipment costs. Further, in rolling with rolling rolls, although the outer diameter surface of the metal small diameter tube body can be rolled, the inner diameter surface is not processed at all, so there is a drawback that the welded portion in particular becomes extremely uneven.

(Objective of the Invention) The object of the present invention is to uniformly process the inner diameter surface of a small-diameter metal tube body, and to process the inner diameter surface of a metal tube body with a reduction rate of 50% or more using a short line and inexpensive equipment. The present invention provides a method for manufacturing a small diameter metal tube.

(Structure of the Invention) The present invention provides a method for forming a small diameter metal pipe containing a threaded body by forming a metal tape around the threaded body and welding the joints of the metal tape to form a small diameter metal pipe body. In the method for manufacturing a tube, the metal small diameter tube body is held from the inside and outside by a diameter reducing die existing on its outer periphery and a floating plug with a filament passage hole existing inside the tube, and is taken off by a pulling machine to reduce the area. After that,
Furthermore, the thin metal tube body is passed through a multistage roll die to reduce the area to a desired area reduction rate.

(Example) Examples of the present invention will be described in detail below with reference to FIGS. 2 to 4. As shown in the figure, a metal tape 2' such as an aluminum tape is supplied from a tape supply 1 to a forming machine 3 to form a pipe, and then a welding machine 4 welds the seam of the metal tape 2' to form a third pipe.
A metal small diameter tube main body 2 having a cross-sectional shape as shown in FIG. A is successively formed. On the other hand, a wire material 6 such as a plastic-coated metal wire or a cored optical fiber wire is supplied from the wire supply 5 to the molding machine 3 and fed into the small diameter metal tube body 2 being molded. The thin metal tube 7 containing the filament thus obtained is cooled by passing through a cooler 8, and then the thin metal tube main body 2 is reduced in area and work-hardened in order to increase the tensile strength. First, the small diameter metal tube body 2 is passed through a sizing roll 9 to reduce its area by several percent, and then the outer and inner parts are removed using a diameter reducing die 10 and a floating plug 12 with a filament passage hole 11, as shown in FIG. The area is reduced while holding the metal small diameter tube main body 2 between the tubes. At this time, the floating plug 12 present in the metal small diameter tube main body 2 is supported at the tip of the introduction tube 13. In addition, lubricant is supplied to the introduction pipe 13 from the outside, and the floating plug 1
It is guided to the front of the floating plug 12, taken out from the hole 14, and supplied to the outer circumference of the floating plug 12 to perform a lubricating action.
At this time, make sure that the inlet pipe 13
A liquid stopper 15 is provided near the tip of the tube. When the diameter of the small diameter metal tube body 2 is reduced using the diameter reduction die 10 and the floating plug 12 in this way, the third
As shown in Figure B, the inner protrusions such as weld beads are corrected and become uniformly arcuate like the other parts, and the inner surface of the metal tube body 2 can also be work hardened. The metal diameter-reducing pipe body 2 is taken from the diameter-reducing die 10 and the floating plug 12 by a take-off machine 16 and passed through a roll die group 18 via a dancer roll 17 to further reduce the area by several tens of percent and cause work hardening. A thin metal tube 7 containing a filament body having a cross-sectional shape of a required size as shown in FIG. Roll dice group 18
For example, as shown in FIG.
are arranged in cascade, such as in six stages, so that the area is reduced sequentially.

When the thin metal tube 7 containing the filament is manufactured in this way, the thin metal tube main body 2 as shown in FIG.
The take-off strength due to work hardening increases slightly due to work hardening with the forming machine 3, but then decreases significantly due to sintering due to welding heat, and then increases slightly due to work hardening with the sizing roll 9. plug 1
It rose slightly due to work hardening due to 2, and significantly increased due to work hardening due to the final roll die group 18, and reached 16Kg/mm ²
or more tensile strength can be obtained.

Example: Aluminum small diameter tube, outer diameter 10mm, made by molding machine 3
φ, wall thickness 0.5 mmt (material AI1050) was formed, and then welded using a welding machine 4, and then the area was reduced in tandem using an area reducing means. The area reduction rate of each area reduction means was determined as follows.

Sizing roll 6% Diameter reducing die 14% Roll die (4 stages) 38% The final shape of the small diameter aluminum tube is an outer diameter of 4.2
mmφ, wall thickness 0.5mmt, and the tensile strength at this time is
It became 16.4Kg/mm ² .

According to the embodiment shown in FIG. 2, since there is a sizing roll, the change in the tensile force caused by the diameter reducing die 10 does not affect the metal small diameter tube body 2 in the part of the welding machine 4, and the metal thin tube body 2 is affected during welding. Breakage of the diameter tube main body 2 can be prevented.

In addition, in the above experiment, the material of the aluminum small diameter tube was
Al1070, Al1100, which is pure aluminum, is used as AIl050.
However, we were able to reduce the area using a similar device and obtain sufficient tensile strength.

In addition, each roll die 2 of the roll die group 18
1 only needs to be rotated in a driven manner without being driven, so there is no need to control the speed between each roll die.

(Effects of the Invention) As explained above, in the method for manufacturing a thin metal tube containing a filament according to the present invention, the thin metal tube body is held between the outside and the inside by the diameter reducing die and the floating plug to reduce the metal tube body. Since the tube faces the inner surface, it is possible to correct irregularities caused by weld beads and the like on the inner surface of the small diameter metal tube body, and also work harden the inner surface to increase the tensile strength. Furthermore, in the present invention, the tensile strength is increased by reducing the area using a multi-stage roll die after that, so that the length of the production line can be shortened and processing to obtain the required tensile strength can be performed using simple equipment. Also, since the line length is short,
It has good workability and is of great industrial value.

[Brief explanation of drawings]

Figure 1 is a diagram showing the relationship between area reduction rate and tensile strength, Figure 2
The figure is a side view showing a schematic configuration of an embodiment of an apparatus for carrying out the manufacturing method according to the present invention, and FIGS. 3A, B, and C.
Figure 2 is a cross-sectional view of the small diameter metal pipe containing the filament body in each part shown in Figure 2, Figure 4 is a longitudinal cross-sectional view of an example of the diameter reducing die and floating plug in an implemented state, and Figure 5 is an example of the roll die group. The side view shown in FIG. 6 is a diagram showing changes in tensile strength in the production line of this embodiment. 1...Tape supply, 2'...Metal tape,
3...Metal small diameter tube main body, 4...Welding machine, 5...Striated body supply, 6...Striated body, 7...Metal small diameter tube with striated body, 9...Sizing roll, 10... …
Diameter reducing die, 11... Firing body passage hole, 12... Floating plug, 16, 19... Taking machine, 18... Roll die group, 20... Winding machine, 21... Roll die.

Claims (1)

[Claims] 1. A method for manufacturing a metal narrow diameter tube containing a filament by forming a metal tape around the filament and welding the joints of the metal tape to form a metal narrow diameter tube body. After reducing the area of the metal small diameter tube body by holding it from the inside and outside with a diameter reduction die existing on its outer periphery and a floating plug with a filament passage hole existing inside it and taking it off with a pulling machine, the metal small diameter A method for manufacturing a thin metal tube containing a filament, which comprises passing the tube body through a multi-stage roll die to reduce the area to a desired area reduction rate.