JPS5853448B2 - Method and apparatus for encapsulating cable core with water-resistant compound - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method and apparatus for manufacturing water-resistant cables.

In particular, it relates to a method of filling gaps in a cable core with a water-resistant compound and encapsulating the compound in and around the cable core.

The background of the prior art is as follows.

In the manufacture of telecommunication cables, especially those intended for burial underground, it is necessary to fill the interstitial spaces not only between the insulated conductors of the core, but also between other parts of the cable, and to prevent moisture from entering the cable core. It is practically desirable to prevent the infiltration of

A method and apparatus for filling cable cores is disclosed in U.S. Pat.
No. 67454 (Japanese Patent Application No. 4761423), the entire disclosure of which is specifically referred to herein.

The system of U.S. Pat. No. 3,767,454 consists of a pair of twisted cable cores in the form of long insulated electrical conductor strands, which have internally bonded dies, move laterally through a series of line chambers, and This method facilitates the expulsion of air from hollow spaces in the structure and the application of a gel-like density water-resistant compound under pressure to the expelled spaces.

The compound-filled cable core is then passed through various stages in which core lubricant and sheath material are installed in combination with other water-resistant compound travel around the core.

A plastic jacket is extruded around the sheath and the coated cable is cooled before being wound onto a reel.

Among other techniques, the method according to U.S. Pat. I discovered that.

Therefore, when applying a core rub, it is necessary to closely match the irregular outer shape of the cable core to avoid creating a cavity between the cable core and the surrounding area of the next applied core rub.

These voids are minimized by using corelab materials that are pliable and easily engineered, such as corelabs formed from random arrays of non-hygroscopic fibers of the type disclosed in U.S. Pat. No. 3,509,269. sell.

However, if we use coreab, which can be easily processed,
Although void formation between the core lubricant and the cable core is minimized, they cannot be completely avoided.

Furthermore, the combination of a cable core wrapped in a highly workable core lub results in an irregular profile and an armored sheath, such as a corrugated aluminum or steel sheath, forming around the cable core and core lubricant. becomes difficult.

As a result, the final cable cannot be completely impermeable to water ingress and migration.

U.S. Patent No. 3733255 (Japanese Patent Application 1973-6)
No. 7576), an encapsulated cable core having an irregular outer shape is passed through a long and narrow tube in the longitudinal direction,
creating an armored sheath around the core and introducing a jelly-like water-resistant compound into the formed tube at a point remote from the population at relatively high pressure to create a layer of water-resistant compound covering the encapsulated core;
The sheath is shown to be formed such that the encapsulated cable core assembly exits the formed tube to provide a smooth cylindrical surface.

The application of pressure as the compound is introduced into the formed tube causes the compound to be introduced between the overlapping ends of the sheath, encapsulating the seams formed at the ends and making them waterproof.

However, this method does not eliminate the voids or air pockets between the core wrapper and the filled cable core.

The present invention aims to provide a new and improved method and apparatus for applying a water-resistant jelly-like compound in the form of an elongated strand, as well as an apparatus for encapsulating a cable core filled with a water-resistant jelly-like compound. do.

Furthermore, it is an object of the present invention to provide a cable structure with an improved filling factor compared to conventional water-resistant cable structures.

A method of applying a water-resistant compound to a strand-like article according to the principles of the present invention involves applying the compound in a substantially fluid state to a continuous portion of the strand-like article under pressure, substantially occupying the voids not occupied by the strand-like elements. Thereafter, the compound is applied under pressure in a substantially viscous state while adhering to the continuous portion of the strand, the linear motion compound is coated and encapsulated therein, the strand is then cooled, and the applied compound is This includes the step of solidifying the.

An apparatus for applying a compound to a strand-like article in accordance with the principles of the present invention includes means for applying a compound in a substantially fluid state to a continuous portion of the strand-like article using an indenter; and means for cooling the article and solidifying both applied compounds.

Referring to FIG. 1, an apparatus 10 is shown for injecting and sealing a water-resistant compound into and around the gap in a cable core 11 passing longitudinally through the apparatus.

Preferably, the device 10 has a lead-in tube 12, which has 1
It is connected to the vacuum chamber 13 through a compressor section or die 16, in which the interstitial cavity body in the core 11 is evacuated.

Core 11 is then passed through die 17 and gradient pressurization chamber or adiabatic cooling chamber 18 .

There is a cooling medium, for example water, which circulates around the room through the inlet 21 and the outlet 22.

It has also been found that under certain operating conditions it may be desirable to circulate the heating medium instead.

After the gradient pressurization chamber 18, the core 11 is passed through the die 23,
A compound application or pressure chamber 26 is passed into which the water-resistant compound in a fluid state is applied under pressure, e.g. 1.4 kg.
Inject into the evacuated cavity in the cable core 11 at a pressure of 7 cm2.

The temperature of the compound in the filling chamber 26 is 38° for a compound consisting of a mixture of petrolatum or petroleum jelly in the range of 80 to 98% and low density polyethylene in the range of 2 to 20%.
-149°C, but preferably ranges from 93° to 110°C for mixtures of 92 thread petrolatum or petroleum jelly and 8x low density polyethylene.

Also, when using a single component compound of petrolatum, the humidity can be in the range of 38° to 121°C, but preferably 77°C.
The temperature ranges from 93°C to 93°C.

As noted above, the apparatus 10 is described in US Pat. No. 376, cited above.
It is almost the same as the device disclosed in No. 7454.

There, the core 11 enters a temperature gradient chamber and then passes through a suitable compressor section or die into a cooling or annealing chamber 28 where a continuous section of the core 11 is cooled and somewhat cooled. The compound is solidified in the core 11 to the extent that it does not flow and has a jelly-like consistency, and the compound is retained in the core 11 while the core is placed in the atmosphere from the downstream end of the annealing chamber 28. It has been shown that

The apparatus described above is modified in certain respects to be novel;
That is, the vacuum in the vacuum chamber 13 is removed.

This causes the hot compounds in the pressurized chamber 26 to flow counter to the direction of movement of the cable core and enter the idle vacuum chamber 13 through the pressurized gradient chamber 18.

Excess compound in chamber 13 exits from there through an opening (not shown) in the bottom of chamber 13 to a collection tank (not shown).

From there it is pumped into the system's main source of compounds.

Removing the vacuum in chamber 13 had the effect of increasing the overall length and therefore increasing the time.

Meanwhile, the cable core 11 is under pressure of a water-resistant compound, which serves to preheat the core 11 moving into the pressurization chamber 26.

This effectively improves the filling and increases the flow rate.

In accordance with the principles of the present invention, a further modification may include a die and cooling compound chamber 32 between the filling chamber 26 and the cooling chamber 28.

As will be seen below, the combination of the die 31 and the cooling compound chamber 32 improves the filling rate of the evacuated cavity in the core 11 and also allows cooling of the compound to be carried out in the annealing chamber 28.
provides an improved encapsulation of filler compound within the core 11 without relying on

Further, the core 11 is in a better condition for the subsequent application of the core jacket, improving the circumferential profile of the core and reducing the possible presence and circumference of a cavity between the filled core 11 and the core jacket. An improvement is obtained that eliminates irregularities in the contour.

As shown in FIG. 1, the device 10 is supported on a stand 33,
It is supported through a separate or pair of parallel rods 34 onto which the various sections or chambers of the device 100 are adjustably fastened.

2-4, the low humidity compound chamber 32 has an inlet tube 35 and an outlet tube 36, which are connected to a passageway 37 for receiving the cable core 11.

The low humidity water resistant compound is the same mixture of petrolatum and low density polyethylene as the filling compound, but at a lower humidity, for example from 15° to 71°C, preferably from 54° to 71°C.
℃ and at substantially the same pressure as in the chamber 26, e.g.
kg/'cm2 and is introduced into the channel 37 in a substantially viscous state.

If a monocomponent compound of petrolatum is used, the temperature should be in the range 43° to 60°C.

That is, the second coating is always performed at a lower temperature than the first coating and is applied in a higher viscosity state.

Cooling water, for example, one with a temperature of 13°C, is connected to the artificial pipe 42,
Continuous circulation through outlet tube 43 to chamber 38 maintains the humidity stability of the compound in low humidity compound chamber 32.

FIG. 2 shows an embodiment of a line for supplying a high-temperature 1i1i4 aqueous compound and a low-humidity water-resistant compound, respectively, using the same raw material, and corresponds to the apparatus shown in FIG. 3.

In this method, the hot compound is first pumped into conduit 46 through valve 47 and into T-fitting 48 connecting conduits 51 and 52.

As shown in FIG. 3, a conduit 51 connects to one or more openings 53 in the filling chamber 26 into which the compound is injected to fill the void body of the cable core 11.

Excess compound is discharged into the filling chamber 26 through a passageway 56 formed in the chamber 26 to admit the hot compound under pressure and flows therefrom through the gradient pressurization chamber 18 and the vacuum chamber 13.

The openings 57 and 58 are provided for measurement purposes, such as measuring and monitoring pressure and humidity (not shown).

The chamber 26 is preferably an annular chamber 6 for circulating steam.
1 to maintain the humidity stability of the compound at high temperatures.

As shown in FIG. 3, the die section 31 is located between the filling chamber 26 and the cooling compound chamber 320.

The die portion 31 has first and second metal wiping dies 62 and 63 and a resilient die 66, which resilient die is preferably made of a frustoconical rubber element; A metal wiping die such as die 63 may also be substituted.

The cable core 11 passes through the filling chamber 26 and into the die part 3
1 and into the cooling compound chamber 32, the core 11, which has a layer of water-resistant compound thereon, is coated with a lower temperature compound which is in a more viscous state.

Similarly, when the cable core 11 passes through the die portion 31 and enters the low-humidity compound chamber 32 (second pressure chamber), the pressure in the chamber 32 causes the elastic die 66 to come into close contact with the cable core 11, resulting in a high temperature This has the effect of forcing the compound (liquid compound) into the gap in the core 11.

As shown in FIG. 2, a valve 67 in conduit 52 controls the amount of water-resistant compound that enters pump 68 in conduit 69 through T-fitting 71 at start-up.

The compound is pumped through heat exchanger 72 into conduit 73 where it recovers sufficient heat from the compound to cool it to the desired humidity and is pumped through valve 76 to cooled compound chamber 32.
Lead to 0 population 35.

The low humidity compound exiting the cooling compound chamber 320 outlet 36 returns to conduit 69 through valve 77 in conduit 78 .

Pressure relief conduit 81 is attached to conduit 46 via T-footing 82.

After operating the system and equipment, valve 67 is closed.

At this time, the high mud compound from conduit 46 does not enter pump 68, but instead pump 68 circulates the compound to conduits 69, 73 and 78.

Operation of pump 68 draws compound from pressure chamber 26 through die 31 into cold compound chamber 32, a portion of which is withdrawn for recirculation through outlet conduit 78.

The high temperature compounds entering the low humidity compound chamber 32 produce the desired result:
That is, the amount is not so large as to adversely affect the coating of the cable core 11 with the water-resistant compound layer.

After leaving the cooling compound chamber 32, the core 11 enters the cooling or cooling chamber 28 and passes through a passage 83, which is maintained at a temperature of, for example, 13° C., cooling both the applied compounds; Solidify to a putty-like consistency.

It is cooled by circulating cooling water from the port 86 to the circulation passage 87 and to the outlet 88.

A die of an appropriate size is attached to the exit portion of the cooling chamber 28, so that the peripheral outer shape of the cable core 11 can be made smooth as shown at 89 in FIG.

5 and 6 show, for comparison, a cable core 11 filled according to the prior art (FIG. 5) and a cable core 11 filled and encapsulated according to the principles of the present invention (FIG. 6), respectively. ing.

As shown in FIG.
provides improved conditions for subsequent application of the core jacket and appropriate armor sheath.

The latter technique described above preferably applies to US Pat. No. 373, cited above.
According to No. 3255 of the elementary school.

The cable core 11 can be preheated, such as in a dryer, before being placed entirely into the device 10 to prevent it from acting as a heat sink for the filling compound.

[Brief explanation of the drawing]

FIG. 1 is a side view of a complete apparatus for injecting and encapsulating a refractory compound into the interstitial space in and around a cable core in accordance with the principles of the present invention. FIG. 2 schematically shows a plan view of the improved molding portion of the apparatus of FIG. 1 embodying the principles of the present invention, and illustrates one embodiment of the method for supplying low-humidity and high-humidity compounds. . FIG. 3 is a detailed partially cross-sectional view of the device section shown in FIG. 2. FIG. 4 is a cross-sectional view taken along line 4--4 of FIG. 3. FIG. 5 is a cross-sectional view of a cable core filled according to prior art principles. FIG. 6 is a cross-sectional view of a cable core filled in accordance with the principles of the present invention. Explanation of main symbols 11...Cable core, 1
2...Leak pipe, 13...Vacuum chamber, 18
...Gradient pressurization chamber, 23, 31...Dice section, 26...Filling chamber, 28...Cooling chamber, 32... Low temperature compound room, 35, 36, 51
... Conduit, 37 ... Passage, 42゜43
......Cooling water pipe, 61...Steam circulation chamber, 63.66...Dice, 72...Heat exchanger. 62°

Claims (1)

[Claims] 1. From the step of first reducing the pressure in the air pocket-like gap of the strand-shaped electric cable in a vacuum chamber, and the next step of filling the gap with a compound using a filling means and subsequently solidifying the introduced compound. In a method of filling strand-shaped electrical cables, the introduced compound is applied in a viscous state under a preset pressure onto the outer surface of the previously filled cable, thereby forcing the liquid compound into the gaps in the cable. , and a method of filling an electric cable characterized by solidifying both a viscous compound and a liquid compound by cooling the filled cable 0 2 Vacuum chamber for evacuating the spatial gap of a strand-shaped electric cable , an apparatus for filling a strand-shaped electric cable with a compound, which comprises a filling means for filling the evacuated cable with the compound and a cooling means for solidifying the filled compound, in which a compound similar to the liquid compound introduced but with a viscous further comprising means for coating with a high viscosity compound under a predetermined pressure, and after the means for coating the high viscosity compound, means for commonly achieving cooling of the high viscosity compound and the liquid compound. A strand-shaped electric cable filling device characterized by: