JPS6330116B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Background of the Invention When connecting aluminum sheaths of the same diameter, welding is generally performed. However, due to the high temperatures of welding, there is a risk of burning out the cable insulation.

To prevent this, we have traditionally done the following:

1. Keep only the welding area at the required high temperature, but quickly cool it from a distance.

In other words, although the welding area is raised above the core (see Figure 1), the aluminum sheath is in contact with the core in the valley of the corrugation near that area. The heat conduction of the aluminum coating is very good. Therefore, if no action is taken, the temperature in the valley will quickly rise to the same level as the welding area. If this happens, the cable insulation is likely to burn out and dielectric breakdown will occur, which is extremely dangerous. To avoid this, it is necessary to cool it down.

2 Perform welding intermittently. For example, after welding for one minute, you rest for the next five minutes. This prevents the temperature from rising.

The following methods are used for cooling.

A. Use of heat absorbing materials. That is, a cream-like heat absorbing material is applied near the welding area to prevent the temperature from rising near the welding area. However, since the heat absorbing material alone does not have a significant cooling effect, it is necessary to take a long break from welding.

b. Use liquid nitrogen or compressed air. Of these, liquid nitrogen requires large-scale equipment and causes oxygen deficiency, so it is not suitable for work inside tunnels. Compressed air has a weak cooling effect. Furthermore, if this device is used a lot, the capacity of the compressor must be increased, which impairs work efficiency.

OBJECT OF THE INVENTION The above-mentioned problems have been solved by using the above-described heat absorbing material and cooling device in combination.

Example (Fig. 1) 10 is a cable core, 12 is an aluminum sheath, 14 is an aluminum connection pipe, 16 is an aluminum collar (for a padded joint), 18 is a welding part, and 20 is a heat insulating material.

As shown in FIG. 1, the welding point 18 of the aluminum sheath 12 must be performed at a location where it is lifted from the cable core 10 (the corrugated material is pushed out and separated from the core 10).

At the welding point 18, the aluminum cover 12 is heated to a high temperature. Heat is conducted through the aluminum sheath 12 and spreads in the longitudinal direction of the cable.

At that time, the most dangerous part is the welding point 18.
This is the corrugated valley (indicated by 13) that comes next. When proceeding to the left from welding point 18 in Figure 1,
Since the aluminum sheath 12 comes into contact with the cable core 10 for the first time at this valley 13, there is a risk of burning out the cable insulator at this part.

Therefore, the aluminum cover 12 adjacent to the welding point 18
Above, at least the valley 13 next to the welding point 18
A heat absorbing material 26 is provided so as to cover the. It is a cream-like product made by kneading, for example, a magnesium compound and aluminum silicate with water, and all that is required is to apply a sufficient amount of the material around the aluminum cover 12 and swell it up.

A hollow ring-shaped mounting jig 24 is provided in contact with the heat absorbing material 26 so as to go around the aluminum cover 12. Then, insert the nozzle 22 of the cooling device into it and blow out compressed air.

After doing the above, welding is performed.

Effect: At the position adjacent to the welded area of aluminum,
Since the heat absorbing material 26 was provided to cover at least the corrugated valley 13 next to the welding point 18 on the aluminum covering 12, and the cooling device for the aluminum covering 12 was provided in contact with it; The heat of the aluminum cover 12 is absorbed by this, and the temperature rise in the corrugated valley 13 is delayed, and this effect is further promoted by the cooling device.

Further, when the heat absorbing material 26 cannot suppress the temperature rise in the valley 13 below a predetermined temperature and welding is stopped, the cooling device provided in contact with the heat absorbing material 26 At the same time, it removes heat and quickly restores its function, and at the same time lowers the temperature of the valley 13 (it does not directly cool the valley 13, but since the aluminum cover 12 has very good heat conductivity, the valley 13 is cooled). ).

Therefore, a cooling device using adiabatic expansion of compressed air is also sufficiently effective.

Therefore, when welding is performed intermittently, the welding time can be made longer and the down time can be made shorter than in the past.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an embodiment of the present invention. 10...Cable core, 12...Aluminum sheath, 1
4... Aluminum connection pipe, 18... Welding location, 2
2... Cooling device, 26... Heat absorbing material.

Claims (1)

[Claims] 1. A heat absorbing material 26 is provided at a position adjacent to the welding point 18 of the aluminum covering 12 so as to cover at least the corrugated valley 13 next to the welding point 18 on the aluminum covering 12, and A method for welding aluminum to a power cable, characterized in that a cooling device for the aluminum sheath 12 is provided in contact with the aluminum sheath. 2. The method for welding aluminum to a power cable according to claim 1, wherein the cooling device blows compressed air.