US1420911A - Apparatus for building up laminate insulation and like structures - Google Patents

Description

C. W. DAVIS AND W. S. BROWN.

m. w. DAVIS AND P. H. w.smm1, EXECUTORS or c. w. DAVIS, DEC'D. I APPARATUS FOR BUILDING UP LAMINATE INSULATION AND LIKE STRUCTURES.

. APPLICATION FILED MAILZQ, I920. 1,420,91 1

3% m H m. m

, form; and paper UNITED STATESNRPATENT OFFICE.

DECEASED;

ECUTORS ASSIGNORS TO STANDARD -UNDERGROUND CABLE COMPANY OF PITTSBURGH, PENNSYLVANIA, A CORPORATION OF PENN SYLVANIA.

APPARATUS FOR BUILDING UP LAMINATE INSULATION AND LIKE STRUCTURES.

Specification of Letters Patent. Patented June 2'7, 1922.

Application filed March 29, 1920. Serial No. 369,638.

To all whom it may concern:

Be it known that we, CHARLES V. DAVIS, residing at Edgeworth, county of Allegheny, and State of Pennsylvania, and V TILLTAM S. BROWN, residing at Pittsburgh, in the county of Allegheny and State of Pennsylvania, both citizens of the United States, have invented or discovered certain new and useful Improvements in Apparatus for Building Up Laminate Insulation and like Structures, of whichimprovements the following is a specification.

Our invention relates to machinery for wrapping sheet material in superposed layers upon a central core or mandrel and for filling and integrating the structure as it is built up, with a substance applied .in llquld form. The invention has a wider field of applicability, but we have conceived and developed it in relation to the making of electrical cables and condensers. We shall describe it as embodied in machinery for making cables, and in the sequel we shall indicate its applicability, first, to the making of electrical condensers, and then to the making of articles of like form regardless of the kind of service to which they are put.

In making electric cables, it is common to envelop a conductor in a body of insulation built upon it and consisting of layers of paper soaked full of and integrated with a substance called insulating compound. The paper is applied in the form ofa ribbon or tape, the successive layers being wrapped on helically; the insulating compound is a petroleum derivative, or an equivalent substance, and is applied in liquid and compound are brought together and built upon the conductor simultaneously, in a single 0 eration.

A difficulty incident o the wrapping-on of the paper lies in the fact that air-bubbles are often wrapped within the turns of the strip. An air bubble so caught and incorporated in the insulation is a point of weak-- ness and becomes a of insulation, when loaded to the'limit of its capacity.

Our invention is directed to the-prevention of such bubble entrapping.-

In the accompanying drawings Figs. 1 and point of breaking down '2'show in vertical-section alternate forms of the cable in service is a machine of our invention. Fig. 3 is a view in transverse section on the plane indicated by the line III-III, Fig. 1. The usual apparatus includes means for causing the unfinished cable to advance in axial line, a reel of tape describing planetary motion around the cable, its axis so inclined that the pull of the advancing cable will unwind the tape from the reel and lay it down upon the cable in the desired helical formation; and, in addition to or in association with these instrumentalities, means are provided for pouring insulating compound in continuous stream upon the point where the tape is being progressively wrapped upon the cable. The difficulty already defined is consequent upon this: that, while during half the planetary turn of the reel the very point, where the tape meets the surface of the cable, is exposed to the stream of insulating compound,'during the other half of the turn, the advancing strip of tape shields that point from direct access of the stream.

Referring first to Fig. 1 of the drawings, A is the cable in course of construction, and it will be understood that, by instrumentalities not shown, it is, when the machinery is in operation, progressing axially, in the-direction indicated by the arrow. The tapereel is indicated at 1; it has planetary motion around the advancing cable; its axis ,,is inclined as shown, and from it the-cable as it advances draws the tape a and lays it down about itself in the helical wrap indi- 'cated.

The planetary motion spoken of is imparted to the reel 1 by .mountingit on an arm 2, carried on a hub 3 rotatable in a bearing concentric with the cable, and by providing rotating means, such. as indicated in the pinion 4, for example.

for this hub conveniently takes the form of the journal box 5, and the hub is conveniently of-annular form, to permit the passage of the cable centrally through it.

Integral with hub 3(is a casing 6 arranged, when the parts are assembled as shown in Fig. 1, to surround, and to form a substantially closed cell or chamber 7 about the cable, at the point in itspadvance where the tape is progressively laid upon its surface. Openings for the free advance of the cable The bearingand for the feeding in of the tape are sufficiently indicated in Fig. l. The journal box 5 is chambered, and the chamber 8 within it is constantly in communication with the chamber formed by casing 6. A duct 9 leads to the chamber 8, and through it, it will be understood, liquid insulating compound at proper temperature may be sup- .plied, and there needs only suitable head or pressure upon this liquid supply to keep the chamber 7 filled constantly with compound.

communication with chamber 8, and to that Under these conditions the very point where the tape comes to place upon the cable isv constantly submerged in compound, and thus the danger of pocketing air at that point is avoided. We have said that the cell or chamber 7 is substantially closed. It will be understood that the cable in the course of building must as it passes into and out of the chamber 7 move with s'ufiicient clearance through the orifices .formed for its passage, and that similarly the tape enter-- mg the chamber must also have sufiicient clearance to permit of its ready advance to the point of application. These conditions being understood, it will follow that liquid insulating compound will during the operation be escaping in relatively small quantities through the openings provided for the entrance and the exit of the cable parts to and from the chamber 7 which overflow may by suitably provided means he collected beneath.. It will thus be apparent that during the operation there is a continual flow of insulating compound throu h the duct 9 and into chamber-7, a part 05 the compound so entering chamber 7-. enteringinto the composition of the cable and part escaping again as overflow. I

The modification shown in Fig. II is easily understandable. Asbefore there is the tape reel 1, borne by an arm 2, upon a hub 3, with means for rotation, such as a pinion t. There is a journal box 5 within which the hub turns. As before, the hub is annular, to permit the advance ofthe cable A. The journal box is chambered, as indicated at 8, and a liquid supply duct communicates with that chamber. c Instead of the enveloping casin 6 of Fig. 1, the hub is in this case provi ed with a liquid chamber 7 arranged to be always in end-annular; and from chamber 7 extends a nozzle 10, directed beneath the advancing tape a, and to the very point where the'tape comes tomposition upon the surface of the cable. Thus it will be understood that the same-essential end is attained as is attained by the apparatus of Fig. I.the very point where tape meets the surface of the cable is always flushedwith compound, to the prevention of air pockets or bubbles. It will of course be understood the proportions are such and the head of liquid is sufficient, to

, stood.

herein .we have indicated that our invention permits of latitude in embodiment; and it will be understood further that the structure may be modified in detail, so long as the essential features which we are about to define are retained.

In the foregoing description the wrappedon material mentioned is paper, and the building up of the insulation'includes a soaking up of liquid, into the pores of the paper. As is well known to cable makers, laminate insulation may be built up of material other than paper-varnished cloth, for instance. This is a material which is not absorbent, and if such a wrapping material be used, then the insulating compound merely fills interstices and seals and integrates the whole...

The compound is of such nature that it may be applied in liquid form. Ordinarily it is such that at,atmospheric temperature it is nearly solid--as nearly solid as it may be, while the'cable retains. the requisite flexibility. In such case the cable-building operation described above is carried out at elevated temperature, a. temperature at which the compound is liquid. But of course a compound which is liquid at atmospheric temperature (and for certain ends compound of such character is used) does not require of the operation that it be performed at elevated temperature. Again, a liquid may be employed whose fluidity is due to the presence of a volatile ingredient, which evaporating will leave the structure firm and coherent.

In building a condenser there is no central body, and the interior conductor is ordinarily not rigid and self-sustaining; accordingly, a central mandrel will ordinarily be employed. In this case too there will ordinarily be little or no advance of the mandrel in axial direction as wrapping progresses; the'wrapped-on material maybe in sheet form, rather-than in ribbon form, and the wrapping'may be truly spiral. With these comments, the applicability of our invention to condenser making will be under- It is not in the electrical field only that such structures are useful; instance the paper cartridges used in shot guns, mailing tubes made of'paper, conduits for various purposes, In makmg these articles and articles for other uses consisting ofa laminate structure integrated with a substance which at the time of building is liquid, our invention is manifestly applicable.

\Ve claim as our invention:

1. Apparatus for winding a strip of material into helical form including a hub rotilting on a bearing, an arm borne by said hub, a reel carried on said arm and adapted to carry the strip to be wound, chambers in said hub and in said bearing in constant comunication one with the other, and means for maintaining through said chambers a constant supply of liquid at the pointof application of a strip unwound from said' reel and coiled upon a forming article advancing in the line of axis of said hub, substantially as described.

2. In a machine for integrating sheet material and liquid material in laminate structure upon a forming body, the combination of a tape-reel having planetary motion about a path of axial travel of a forming body, a hub upon which said reel is carried, a bearing forsaid hub. chambers in said hub and said bearing constantly in communication one with another, a fluid-supply duct leading to the chamber in the bearing, the chamber in the hub shaped and arranged to envelop the point where the tape comes progressively to shape upon the forming body, substantially as described.

3. In a machine for building laminate cylindrical bodies of insulation, the combination of a tape-reel having planetary motion around a path of axial travel of a cylindrical body, a hub upon which said reel is carried, a bearing for said hub, chambers in said hub and in said bearing in constant communication one with another, a fluid supp lyduct leading to the chamber in said bearingand means for maintaining through said chambers a constant supply of liquid at the point of application of a strip unwound from said reel and coiled upon a cylindrical body advancing in said path of axial travel, substantially as described.

4. Apparatus for integrating sheet material and liquid material upon a forming body, including a reel for the sheet material having planetary motion about the forming body, and means for causing the liquid material flowing in a stream constantly to submerge the sheet material and the forming body at the point where the sheet material meets the surface of the forming body, substantially as described. a

In testimony whereof we have hereunto set our hands. 7

CHARLES V. DAVIS. VVI'LLIAM S. BROWN. lVitnesses JOHN W. SHIBLER, HARRY G. BURD.

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