JPH0139285B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION When cables having cable metal sheaths such as aluminum sheaths are connected with the same diameter, the cable metal sheaths are also connected with the same diameter.

At that time, as shown in "Figure 1", the metal pipe 1
0 onto one cable metal sheath 20, and after connecting the cable core 30, move it to a predetermined position (Fig. 2), squeeze it until it has the same diameter as the sheath 20 (Fig. 3), and then Connect by welding, etc.

Conventionally, this drawing was done only by cold working using swaging rollers. Therefore, when the metal pipe 10 has a large diameter, there are drawbacks such as wrinkles forming and the pipe becoming polygonal instead of round.

This invention eliminates such drawbacks, and instead of drawing the metal pipe 10 only by cold working, the first drawing is done by cold working, but after that, that is, from the second drawing. The process of annealing and squeezing is repeated until it reaches a predetermined thickness.

That is, when the metal pipe 10 is first subjected to cold drawing, work hardening occurs. Therefore, from the second time onwards, cold drawing is performed after annealing.

The term "annealing" refers to "the operation of heating a metal material to an appropriate temperature and then slowly cooling it to room temperature" (edited by Industrial Education Research Association, Nikkan Kogyo Shimbun, Inc.).
Illustrated dictionary of mechanical terms).

When heating, the most important thing is not to adversely affect the cable core 30 immediately inside.

In the case of aluminum, if you heat it to about 150 to 200 degrees Celsius, do it in as short a time as possible, and then cold draw it at considerable intervals, it will not have a negative effect on the cable core 30. I won't give it.

Note that heating at appropriate intervals has the following meaning.

In other words, even if the temperature of the cable core insulator is below the allowable temperature during the first heating, if heating is performed one after another without any intervals, the temperature of the cable core insulator will gradually rise. , the temperature finally exceeds the allowable temperature.

Therefore, even if you heat the metal pipe multiple times,
It is only necessary that the temperature of the insulator of the cable core is below the permissible temperature, and the heating interval can be determined so as to keep it that way.

In reality, in the annealing operation, the drawing process is performed after waiting for the metal pipe to cool down to room temperature as described above, and the drawing process also takes time, and by then the temperature of the cable core has increased. After the drawing process is completed, the next annealing operation can be carried out.

In addition, the heating method must be (1) capable of rapidly raising the temperature to a specified level in the shortest possible time, and (2) capable of uniform heating (avoiding the formation of localized high-temperature areas). .

The following are suitable as such:

(1) Direct energization heating (Fig. 4) 40 is a transformer for energization, 42 is an electrode, and water 44 is made to flow inside.

According to this method, the temperature rises quickly. Furthermore, since the electrode 42 is cooled, a local temperature increase at the contact portion between the electrode 42 and the metal pipe 10 is prevented, and the entire area is heated uniformly. Also, only the metal pipe 10 is heated.

(2) Induction heating method (Fig. 5) 50 is a heat-resistant insulated pipe, 52 is an induction coil, and 54 is a high-frequency oscillator. In this case too,
The temperature of the metal pipe 10 rises quickly. Also, only metal pipes are heated.

Effects of the Invention Even if the metal pipe 10 has a large diameter, it can be narrowed into a neat circular shape without adversely affecting the cable core 30.

[Brief explanation of drawings]

Figures 1, 2, and 3 are explanatory diagrams showing a common method for connecting cable metal sheaths of the same diameter in the order of steps, and Figures 4 and 5 are illustrations of examples of the heating method in the present invention. It is an explanatory diagram. 10... Metal pipe, 20... Cable metal sheath, 30... Cable core, 42... Electrode, 5
2...Induction coil.

Claims (1)

[Claims] 1. A metal pipe fed in advance,
After connecting the cable core, move it to the specified position,
In a method for connecting a cable metal sheath with the same diameter, the diameter of the metal pipe is reduced to be equal to that of the cable metal sheath, and the metal pipe is first reduced by cold working;
A method for connecting cable metal sheaths of the same diameter, which is characterized by repeating annealing and squeezing from the second time onwards until the metal sheath is squeezed to a predetermined thickness. 2. A method for connecting cable metal sheaths of the same diameter according to claim 1, characterized in that the heating of the metal pipe is performed by a direct current heating method. 3. The method for connecting cable metal sheaths with the same diameter according to claim 1, characterized in that the metal pipe is heated by a high-frequency induction heating method.