US3365357A

US3365357A - Method of making twinned pulp insulated conductors

Info

Publication number: US3365357A
Application number: US449821A
Authority: US
Inventors: Christopher J Krogel; Axel C Nystrom
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1965-04-21
Filing date: 1965-04-21
Publication date: 1968-01-23
Anticipated expiration: 1985-01-23

Description

2 Sheets-Sheet IAA/EN TUQE C'. L KFQDE'E'L. IC7. C'. NYE' TRD/77 C. J. KROGEL. ET AL METHOD OF MAKING TWINNED PULP INSULATED CONDUCTORS Jan. 23,v 1963 Filed April 2l, 1965 Jan. 23, 1968 C. J. KROGEL ET AL 2 Sheets-Sheet 2 Filed April 2l, 1965 United States Patent O 3,365,357 METHOD F MAKING TWINNED PULP INSULATED CONDUCTORS Christopher J. Krogel, Cranford, and Axel C. Nystrom,

Rutherford, NJ., assignors to Western Electric Company, Incorporated, New York, N.Y., a corporation of New York Filed Apr. 21, 1965, Ser. No. 449,821 7 Claims. (Cl. 162-106) This invention relates to the manufacture of insulated conductors, and more particularly to twinned pulp insulated conductors and the method of making suc-h conductors.

In the manufacture of electrical communications cable, it is necessary that the cable be fabricated in such a manner that one can readily identify individual pairs of insulated conductors therein and distinguish each insulated conductor of each pair. It is also necessary that the pairs of the cable be twisted with different twist lengths in order to preclude cross-talk between the sever-al pairs of conductors therein.

If the pairs are twisted in short lengths, as has been the custom in the past, the twisting thereof also will serve to bind the two conductors of each pair together to keep the several pairs distinguishable Ifrom ea-ch other. However, if the twist length is relatively long, the conductors tend to be substantially parallel and difficulty arises in identifying the conductors of the pairs in the field, for example, when it is required to splice conductors together from one cable to another. Because of the longer twist length the conductors of a pair tend to separate and the vmaking of improper connectionsl may result.

As mentioned above, in the past the problem of separation ofthe conductors `of a pair had been obviated by twisting the pairs of conductors in short lengths. This was Ipossible since the insulating and twisting operations were conducted separately. Initially, the conductor was coated, for example, in a pulp insulating machine, reeled and stored; then, at a later time, the reels were sent to twister units where single conductors from two reels were twisted together and collected on a single reel. Under these conditions, it was possible to run the twisters at a high angular velocityv and, therefore, to impart twists of short length to the wires. The use of a high angular velocity was possible since there was no time limitation when stopping the twister units to change the twisted pair reels. v

It has -been found, however, that it is advantageous economically to utilize a continuous process of insulating and twisting pairs of conductors rather than the separate operations outlined above. In this continuous type process there is a time limitation involved in stoppin-g the twister units to change reels, sin-ce the conductors are being fed continuously from the insulating apparatus. Because the angular velocity of the twister unit must be lower in a continuous operation to match the relatively low velocity of the pulp insulating machine, and additionally lower to allow for reel changes, twists of longer lengths are imparted to the pairs. However, as set forth above, longer twists lengths lead to the possibility of strand separation. One method of avoiding this condition is to provide two conductors with a unitary coating of insulation. However, if this method is used without taking remedial steps, it will be impossible to identify each conductor of the pair for splicing purposes. In addition, the two conductors of the pair may be forced together during twisting, causing shorts.

It is, accordingly, an object ofthis invention to provide a new and improved process of making pairs of insulated conductors which may be twisted in twists of relatively 3,365,357 Patented dan. 23, 1968 large lengths without the possibility of conductor separation and loss of identity.

It is another object of this invention to provide a method of manufacturing pairs of conductors having a unitary covering of insulation wherein each conductor of the pair and the pair itself may be readilyfidentitied.

It is another object of this invention to provide a pair of conductors having a unitary covering of insulation wherein each conductor of the pair may be readily identied.

It is another object of this invention to provide a pair of conductors having a unitary covering of insulation wherein adequate spacing is attained between the two conductors. In accordance with the objects, the process comprises coating one conductor with an insulating material, coding said coating with a iirst marking, coating a second conductor with an insulating material so that it -has an excess portion thereon, and wrapping the excess portion of said insulating material about both conductors to form a unitary coating about the conductor pair.

These and other features, advantages and objects of the invention will be understood clearly from the following detailed description and the accompanying drawings wherein:

FIGS. l-lF inclusive, is a schematic sequence illustrating a process of making twinned pulp insulated conductors with schematic showings of the conductors at each step in the process;

FIGS. 2A-2I inclusive, is a schematic sequence illustrating the various stages of fabricating the twinned pulp insulated conductors;

FIG. 3 is a partial view of a rotatable screen which forms the ribbons of pulp on the conductors; and

FIG. 4 is a view of a twisted pair of pulp insulated wire-s.

With reference to the drawings, a container 12 having a drum 14 rotatably mounted therein is partially submerged in a pulp suspension 16 which -consists of pulp suspended in water. Drum 14 includes annular foraminous portions 18-18 through which the water may pass, as at 20, so as to strain the pulp thereon. Annular portions 18--18 are separated by a plurality of stripes 22-22 (FIG. 3) which are painted along the length thereof -with a material to block the formation of pulp in these regions. The pulp strips or ribbons 24-24 and 26-26 of respective predetermined widths are formed between the stripes 22-22. To maintain the proper level of suspension 16 in container 12, means (not shown) are provided to supply the pulp suspension from a mixing vat to the container in a manner which insures a continuous ilow of suspension to the foraminous portions 18-18, the water flowing therethrough and being drawn oil by yconventional means (not shown).

A plurality of conductors 28--28 in strand form (shown in FIG. 1 and schematically in FIGS. 2A and 2B) are fed from a plurality of laterally disposed supply reels (not shown) `and guided by roller 30 into the suspension and about the foraminous portions 18-18 of rotating drum 14. As drum 14 rotates each conductor 28 receives a ribbon of pulp when it passes through suspension 16 thereby forming ribboned conductors 31-31 and 32-32 (FIG. 3).

An endless belt 34, of a soft, liquid absorbing material such as felt, travels around rollers 36-36, transfer roller 37, and lower roller 38 of a set of press rollers 39, to facilitate freeing t-he ribboned conductors 31-31 and 32--32 from the drum 14. The belt 34 is urged into contact with the drum by transfer roller 37 which, therefore, rotates with the drum. The ribboned conductors then travel with the lupper surface of belt 34 through the press rollers 39 which squeeze moisture therefrom. Immediately thereafter, the ribboned conductors are separated from the belt 34 and passed around guide rollers 44 and 46 to a housing 4S.

In a preferred embodiment, the ribboned conductors are separated into four groups by rollers StD-50', each group consisting of conductors having ribbons of a similar iwidth. The groups of ribboned conductors are fed through four vertically disposed entrance slots 52-52 of the housing 48 which contains polishers 54-54 in the path of the narrow ribboned conductors. The term polisher as used herein is defined as a mechanism, such as a series of rotating blocks, for Wrapping the pulp ribbon around a conductor. As is shown schematically in FIGS. 1A and 1B, the narrow ribboned conductors S51-31 are fed through the polishers 54-54 while the wide ribboned conductors 32-32 simply pass through housing 48 unchanged (FIGS. 1D and 2F). As a result, the polishers 54-54, wrap or transform the ribbon coatings 26 of the narrow ribboned conductors 31-31 into coatings 2626 which are substantially concentric with the conductors 28-28 (FIGS. 1C and 2E), these conductors being designated 3131.

After exiting from housing 48, the conductors 31'31 and 32--32 are guided around rollers 60-60 to a roller 61 where they are `again laterally disposed to each other in a horizontal plane. At this point, the conductors 3131 are separated from the wide ribboned conductors 32-.32 by rollers 62-62 in order that the former conductors may pass to a suitable dye depositing means 64 'whereat a colored marking 56 is deposited onto conductors 31-31. The conductors 31-31, now colored, and wide ri-bboned conductors 32-32 are again gathered at a common roller 66, whereat, as seen in FIG. 2G, the conductors 31-31 are positioned in contacting relationship with the top surface of ribbons 2li-24 of the wide ribboned conductors 32-32.

The conductors 31'-31 land 32-32 are separated into groups of two as they travel about roller 66, each group consisting of a conductor 31', now polished with a coating 26-26 and having colored markings 56-56 thereon, in contact with a wide ribboned conductor 32. Each group is fed around guide rollers 68-68 and through entrance slots 70--70 of a housing 72 wherein polishers 74--74 are mounted, each polisher functioning to polish ribbon 24 about both its own conductor 2S and conductor 31 in contact therewith (FIGS. 2G and 2H) in the following manner: each polisher 74 positions ribbon portion 24a about coated conductor 31 and ribboned portion 2li/J about its own conductor 28 to form a twinned pulp conductor '76 having a unitary coating 77, as shown in FIGS. 1E and 2l.

After exiting from housing 70 the twinned conductors 76 are guided around rollers 78--78 to a roller 80 where they are laterally disposed. The twinned conductors 76 are then advanced to a second color marking station 82 whereat the unitary coating 77 is coated with a desired colored marking 84. Either a continuous or intermittent marking or coloring, depending on the type of identiiication code desired, may be applied.

One advantage in coating one conductor initially by this method is that sufficient pulp may be provided between the conductors of a twinned pair for maintaining proper spacing of the two conductors in order to prevent shorts. Another advantage in providing a twinned conductor 76 with a double coded coating of pulp insulation around one conductor, i.e. conductor 28 (FIGS. 1E and 2l) is to facilitate a rapid identification of each conductor of the pair. The colored coating 56 of the coated conductors 31 allows each conductor of the pair to be readily identified for splicing purposes. Of course, the unitary coating 77 around the twinned conductor 76 allows the ready identification of each of conductors in a multicenductor cable.

The twinned conductors 76 are fed through drying

ovens

86 and 88 to remove moisture from the pulp and to cause the insulation to set on the conductors. Oven S6 is maintained at a relatively high temperature at the entrance portion e.g. 1500 F. and a relatively lower temperature at the exit portion e.g. 800 F., with a constant gradient along its length to control the evaporation of the moisture from the pulp insulation of the conductors passing therethrough. It has been found that this single oven will satisfactorily dry lthe moisture from the pulp of normally coated conductors. However, in the event Ian excess of moisture was imparted to the pulp insulation, the heat in oven 86 may not be Asufficient to dry out this excess moisture. Therefore, applicants have provided a second oven 88 in series with oven 86 to insure a complete dry out of the insulation. Oven 88 is maintained 'at a temperature high enough to evaporate any moisture which may have remained in the insulation of conductors passing therethrough, but low enough not to burn the insulation of the dried conductors. This temperature is in the area of 250 F., varying with the gauge of the 'wire being fabricated and the thickness of the insulation being applied thereto.

When the twinned conductors 76 exit from oven 88 they are guided by roller l to a twisting apparatus 92 where a twist of a relatively long length is applied rapidly to the continuously advancing conductor, since there now `is no danger of the two conductors in the twinned conductor 76 becoming separated. A twisted pair 76 of pulp insulated wire is shown in FIG. 4. l

It is to be understood that the above-described arrangements are simple illustrative examples of the appli- -cation of the principles of the invention. Numerous other arrangements may be readily devised by those skilled in the art, which will embody the principles of the invention and fall within the spiri-t and scope thereof.

What is claimed is:

1. The method of making twinned insulated electrical conductors comprising the steps of:

applying insulating material about a first conductor,

applying insulating material about a second conductor with an excess portion extending therefrom, and wrapping the excess portion of said insulating material first about the second 4conductor and thereafter about the insulated iirst conductor t-o form a unitary covering of insulating material about the two conductors.

2. The method of making insulated electrical conduc tors comprising the steps of:

applying a ribbon of pulp insulating material to a first conductor,

polishing said ribbon of insulating material about the first conductor so as to form an insulated covering concentric therewith,

applying a relatively wider ribbon of pulp insulating material having an excess portion to a second conduct-or, and

polishing the excess portion of said wider ribbon of insulating material about both the second conductor and the insulated first conductor to form a unitary covering of insulated material about the two conductors.

3. The method of making pulp insulated electrical conductors comprising the steps of:

applying a ribbon of wet pulp to a lirst conductor,

polishing the ribbon of pulp about the iirst conductor so as to form a covering of pulp concentric theren with,

coloring said concentric pulp -covering wit-h a rst color,

applying a relatively wider ribbon of wet pulp of a second color to a second conductor,

polishing the relatively wider ribbon about both con-l ductors to form a unitary covering of pulp about the two conductors, and

drying the pulp coverings.

4. The method of making insulated electrical conductors comprising the steps of:

covering a iirst conduct-or with an insulating material,

covering a second conductor with an insulating material with an excess portion extending therefrom,

placing the insulated vrst conductor and the insulated second conductor in contact with each other, and

Wrapping one section of the excess portion of said insulating material about the insulated first conductor and the remaining se-ction of the excess portion of said insulating material about the second conductor and first conductor to form a unitary coating of in sulating material about the two conductors.

S. The method of making insulated electrical conductors comprising the steps of:

covering a 'first conductor with a wet insulating material,

covering a second conductor with a wet insulating material so that it has an excess portion thereon,

Wrapping the excess portion of said insulating material about bot-h the second conductor and the covered first lconductor t-o form a unitary coating of insulating material about the two conductors,

subjecting the coverings of insulating material about the two conductors to a heating atmosphere to dry the insulation, and twisting the tw-o insulated conductors with a twist of a desired length. `6. The method of making twinned insulated electrical conductors according to claim 1 comprising the steps of: providing identifying indicia on at least one of the insulating materials. '7. The method of making insulated electrical conductors according Ito claim 2 compri-sing the steps of:

applying a coded marking to the insulated covering of the tirst conductor, and applying a coded marking to the unitary covering formed about both conductors.

References Cited UNITED STATES PATENTS 1,800,411 4/1931 Selvig 174-110 X 1,968,903 8/1934 `Norton 174-112 2,947,652 8/1960 Burr 174-1l7 LARAMIE E. ASKIN, Primary Examiner.

E. GOLDBERG, Assistant Examiner.

Claims

1. THE METHOD OF MAKING TWINNED INSULATED ELECTRICAL CONDUCTORS COMPRISING THE STEPS OF: APPLYING INSULATING MATERIAL ABOUT A FIRST CONDUCTOR, APPLYING INSULATING MATERIAL ABOUT A SECOND CONDUCTOR WITH AN EXCESS PORTION EXTENDING THEREFROM, AND WRAPPING THE EXCESS PORTION OF SAID INSULATING MATERIAL FIRST ABOUT THE SECOND CONDUCTOR AND THEREAFTER ABOUT THE INSULATED FIRST CONDUCTOR TO FORM A UNITARY COVERING OF INSULATING MATERIAL ABOUT THE TWO CONDUCTORS.