US1009731A - Method of forming electric cables and apparatus therefor. - Google Patents

Description

H. W. FISHER. METHOD OF FORMING ELECTRIC CABLES AND APPARATUS THEREPOR.

APPLICATION FILED OCT. 21, 1910.

Patented Nov` 28, 19M.

LDDDJMT WITN ESSESI v INVENTOR Atty' huniTEn sTATEs PATENT oEEioE.

HENRY W. FISI-IER, OFPITTSBUBGH, PENNSYLVANIA, ASSIGNOB. T0 STANDARD UNDER- GROUND CABLE COMPANY, 0F PITTSBURGH, PENNSYLVANIA, A CORPORATION 0F PENNSYLVANIA.

METHOD FOBMING ELECTRIC CABLES AND APPARATUS THEREFOR.

Specication of Letters Patent.

Patented Nov. 28, 1911.

Application filed October 21, 1910. Serial No. 588,285.

improvements the following is a specification.

lily invention relates to electric cables.

More particularly my invention has to do with the linal step in the manufacture of cables, sheathed in lead or other. materials, and the object of my invention is to provide a method of manufacturing such electric cablesl to the end that a more efficient cable may be secured. The means employed in accomplishing this method are illustrated inl the accompanying drawings which `form a part of my specification. j

lln these drawings Figure 1 is a plan of a kettle with its lid removed and a portion of alead press with a means for carrying the core, submerged in the insulating compound, from the former to the latter, and Fig.. 2 is a vsection taken on line lll-lll of Fig. l showing, in additionktle lid in place.

lliike parts bear the same reference numerals in both figures.

By the term core, herein used, is meant thev conductors after they have been surrounded with coverings of coherent insulating materials', such as paper fabrics or other suitable materials, and before the same has been covered with a sheath.

llt is well known that the quality of an electric cable, aside from its conductivity and structural strength, is largely dependent upon the ethciency of its insulation. insulation is accomplished primarily by fabrries and papers arranged in suitable ways about the conductors to accomplish their separation from each other and from any possible adjacent conductors. lt has been discovered that these insulating methods in! themselves embody two weak points, namely, accumulated moisture and air spaces. These points of weakness have been temporarily eliminated by placing the core ina reservoir capable of being made air tight, and treat! ing the said core therein as hereinafter described. 'lhe reservoir 1s first heated, so as l to drive thel moisture from the core, and

a vacuum is created therein. In the pressure of this vacuum the air, incased in the various parts of the core, will be extracted, and any moisture that may have remained after the heating of the core will be vaporized. At this lpoint advantage is taken of the vacuum toY inject a heated insulating compound, of more or less duid consistency, into the existing cavities. The said compound 'is introduced' through any suitable opemng, after which the bath, with its submerged core, is subjected to atmospheric pressure. llt will be apparent that in this heated state the insulating compound under the pressure of the air will impregnate the entire core, thereby filling the cavities, hence eliminating the weak points caused by the same.

'llhe core is kept submerged in the insulating compound until both are cooled to a normal temperature, to the end that, as the compoundd in the interior of the core shrinks, while cooling, additional compound will flow therein. lifterA the core has been treated as thus far described, the present practice is to take it from the compound within the reservoir and place it in a suitable position `to be fed intol the lead-press. ln doing this it will be apparent, first, that the semi viscous insulating compound will drip from the exterior of the core,vthereby rendering it liable to the formation. of new air cavities; and second, that these air cavities will be incaseol within the lead sheath 'together with a portion of the air surrounding the core. rlhere'tore the cable will be weakened just in proportion to the amount of air incased within the lead sheath during the sheathing process. lt is toward the improvement of this last step in the method of forming cables that l direct my invention, and the improvement consists in providing a means whereby the core, after it has once been submerged in insulating compound, may be kept surrounded by the same until the core is inclosed within 'its lead sheath.

Any suitable means may be employed to bring the core in its submerged condition to a suitable position for leading. As for example, the kettlemay be transferable from Vone position to another by means ofv trucks while on its passage to the lead-press. Preferably I employ the former method, namely, a system of transferable kettlesv whereby eachfkettle, containing a reel of core, may, in the course of procedure, be taken successively to steam heating pipes, vacuum pump, insulating compound tank and cooler; an din these successive positions the moisture ,is driven from the core, air is exhausted from the kettle, the core within the kettle is submerged in hot insulating compound and the bath is cooled to a more viscid condition.

The kettle may be of anyy suitable -form f and material to accomplish the desired end.

structed that their connections to the steam-- As shown it consists of the main body 1 and a lid 2, between which is interposed a suitable gasket 22 to insure an air-tight connection. l The outside of the kettle may be provided with suitable trunnions 3 for handling the same, and on the inside are trunnion bearings 4, on which the contained reel 5 is rotatably supported. The kettle` is further provided With suitable openings to accomplish the various steps in the treatment of the core as heretofore described. Near the top of the kettle I conveniently provide a pipe and valve 6, whereby connection may be made to the air pump when it is desired to produce a vacuum within the said kettle, and at the top is 'an opening 21, through which air may enter after/the insulating compound has been admitted. At the bottom is a pipe 7, through which the insulating ,compound may be conveniently entered, and the pipes 8 and 9, connecting with the steam heating coil 10, provide means of attaching the same to a steam supply pipe.

` It will be understood of these various connection pipes that they are preferably secured rigidly to the kettle and are so conpipe, air-pump, and vacuum-tank may be broken, thus leavingy the kettle with its .small protruding pipes free 'to be taken from place to place.

- Attached to the kettle I provide means for unreeling the core, to the end that it may be constantly submerged in the insulating-compound. As shown in the drawings I accomplish this byusing aconduit 11 of such shape that the core in passing out will not be suiliciently bent to cause any injury thereto, an air-tight gate valve 12 to retain theV insulating-compound when the core `is not being leaded, and an open top box 13. The top of this box 13 is placed at a level supposably above that of the compound in:

the kettle. However, to guard against the compound overflowing the box 13 coinci-v dent with the opening of the valve 12 in case too much compound had been allowed to enter the kettle, I provide an escape pipe 14. Furthermore the end of the box 13 has a cylindrical protrusion, suitablyV threaded that connection may be made to a flexible pipe 15, which connects the kettle with the 'lead-press. .l

The lead-press may be of any suitable form and type of construction. The essential parts thereof may be arranged as shown in F ig. 2, wherein the block 16 contains the hot lead chamber 17, in which the proper pressure is sustained by The block 16 is suitably threaded for connection to the nut 19, one end of which is end of the said nut bears against the thimble 20, to the end that a turning of the nut will change the thickness of the forming lead sheath. The nut and thimble maybe of any form such that they permit the passage of the core surrounded bythe insulating compound.

The operation of my invention is as follows A reel of core 5 is rotatably mounted upon the trunnion bearings 4 in the interior of uthe kettle. Upon the free end of the core a clevis is attached and the core unreeled suiiciently to permit its clevised end to lie close to the gate-valve. The core is then treated in the. ordinary manner by heating it, subjecting it to a vacuum, impregnating it with insulating compound, and then allowing the kettler with its contents to cool to a working temperature. When a working temperature of the cmpound has been reached, the kettle is connected to the leadpress and the gate valve opened, after which Jpipe 15, the nut 19, the thimble 20 and into a short piece of lead pipe that has been pre- Viously run, the .end of which has been closed. By means of a suitable hook, manipulated from the box 13, the clevised end of. the coreis engaged and pulled into the box is further used to give access to the core so' thatfit may be pushed alon until its end lreaches theaposterior end cfg the thimble, after which the pressure of the'lead suiicieilltly pulls upon the core to cause it to unree It'will be observed of my invention that, after the core hasbeen placed in the insulatingcompound'bath, it is at no time exposed to the air. v Furthermore, in case of extraordinaryrspeed being required in the manufacture of a cable, the core may be leaded while thecompound in a hot fluid state, thereby eliminating the time required for cooling and at the same time preventing the compound vfrom iowing out of the core. However, I prefer, for reasons hereinbefore explained, to sheath the core after the compound has cooled.

the plunger 18.

the compound will How into, the box 13, the

sald box where the clevis is removed. ThisV connected to the flexible hose 15. The other l claim herein as my invention:

l. The herein described method of manuacturing sheathed insulated cables which consists, in driving the moisture and air from acoreby subjecting it to a vacuum, flooding the moisture and air-ridden core with insulating compound, drawing the core temperature,

from said compound and simultaneously with its'withdrawal surroundingv said core to the exclusion of air with a'sheath.

2. The hereindescribed method of manu- -acturing insulated lead-sheathed cables,

`which consistsin maintaining a bath of insulating compound in fluid state at an elevated temperature, with an extended por tion in viscid and contracted state at reduced portion of said bath, and withdrawing such core from said bath through the viscid portion thereof, and,A simultaneously with the .withdrawal of said core from such bath surrounding it and its adhering envelop of insulating compound, to the exclusion of air, with a sheath.

" 3. In an apparatus for making sheathed i and insulated electriccables, a combination of a sheath-applying mechanism, a kettle which when closed may be'made air-tight and within which a reel of cre may be immersed in -insulating compound and a conduit leading from said kettle to said mechanism', through whichI a core, enveloped incompound, may befed immediately to the immersing a core in the fluid while still immersed in the compound, a

valve in said passageway capable of hermetic closure, and an openingin said passageway adjacent to but beyond said valve, aii'ording access to the interiorof said passageway, substantially as described.

5. In an apparatus for making sheathed andinsulated electric cables, the'combina- `t-ion of an air-tight kettle provided with connections for the removal of air and` moisture and the introduction 'of vinsulating compound, a sheathapplying mechanism,

and a conductor leading from said kettle-to said sheath-applying mechanism, through which -a cable core constantly submerged in insulating compound may advance, lsubstantially as described.

In testimony whereof, I have hereunto set my hand. l

' i HENRY w. FISHER.

i Witnesses l BAYARD H. CHRISTY,

- `Pani. N. CRrroHLow.

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