US3017450A

US3017450A - Cables

Info

Publication number: US3017450A
Application number: US841754A
Authority: US
Inventors: Charles H Crosby; William T Hicks; Roger R Wahlberg
Original assignee: Western Electric Co Inc
Current assignee: AT&T Corp
Priority date: 1957-07-19
Filing date: 1959-09-23
Publication date: 1962-01-16
Anticipated expiration: 1979-01-16

Description

Jan. 16, 1962 c. H. CROSBY ETAL 3,017,450

CABLES Original Filed July 19, 1957 2 Sheets-Sheet 1 JNVEN'T'UFQE 1-4, EFQUEE Y LU.'7T HICKS 1-7. LUFIl-IL. Eel-1 G Jan. 16, 1962 c. H. CROSBY ETAL CABLES 2 Sheets-Sheet 2 Original Filed July 19. 195'? 1:.1-4. EEEY u /.'17 HIE/ 5 Fe. R. LUIIJHLEER'LE United States Patent 2 Claims. (Cl. 174-34) This is a division of, applicants co-pending application Serial No. 672,890, filed July 19, 1957, now Patent No. 2,924,930, and the invention herein rel-ates to cables, particularly to telephone cables.

Early in, the history of the manufacture of cable for use it became obvious, that for cable of any considerable length special precautions were. required to prevent the voice currents in one pair of wires from inducing in adjacent wires similar currents which would give rise to the phenomena generally known as crosstalk.

It is accordingly common practice as a first step to make twisted pairs of wires having different numbers of twists per unit length. These pairs of different twist lengths are then twisted together in groups to form complete cables or to form so-called unit type cable. In preparing to make the cable, care must be taken to arrange the payoff from the supply reels so that. pairs of the same twist length do not occupy adjacent positions in the completed cable.

In the case of unit cables the pairs are selected to insure that those in the outer layers in adjacent units are of different twist lengths since in the cabling operation the units of a conventional unit type cable tend to remain in the same relative orientation throughout the cable length. It therefore has been necessary to make up and keep in stock a number of difierently composed types of units in order to be able tomake a multi-unitcable which is satis factory from the cross-talk standpoint.

The general object of this invention is to simplify the construction and reduce the cost of making telephone cables which have a low level cross-talk between the various circuits in the cable.

According to the general features of the invention, a cable having a plurality of units or groups of twisted pairs of wires is made in one operation directly from twisted pairs and with a distribution pattern of the pairs which varies continuously in a non-repetitive manner throughout the length of the cable. All the pairs of wires which are to be cabled together are fed toward a cabling apparatus and those which are to form each unit or group are directed to their proper relative location with respect to the other units. Prior to cabling the units together, the wires of each unit are subjected to a reverse twisting operation about the axis of the unit at a different and varying length to produce a random lay of the wires in the completed cable. This may be accomplished for example by passing the pairs of each group or unit being fed to the cabling apparatus through a separate face plate having a perforation for each pair and oscillating the several face plates independently of each other at rates which vary slightly in a random manner. One very convenient way of attaining the random rate of oscillation is to drive each face plate with a separate direct current motor as explained in more detail below.

Other objects and advantages will be apparent from the following detailed description when considered in conjunction with the accompanying drawings wherein:

FIG. 1 is a schematic top plan view of the apparatus;

FIG. 2 is a fragmentary wiring diagram for the individual motors for the oscillating units;

FIG. 3 is a vertical sectional view of one of the oscillating units and its motor drive;

3,017,450 Patented Jan. 16, 1962 FIG. 4 is a front elevational view' of a face plate of one of the oscillating units; and

FIGS. 5 and 6 are schematic illustrations of certain of the groups of wires which may be employed in forming. a cable.

In FIG. 1 the heavy lines 10 represent, schematically, supply stands. In the present instance, 26 reels containing pairs of Wires are supported for each heavy line (supply stand) to supply their wires as desired in forming a cable core 11. Lines 12 represent the groups of 26 pairs of wires being directed to units 14. The units 14 are similar in structure to that shown in FIG. 3, the, only difference being in the inherent differences of the driving motors. Returning to FIG. 1, lines 15 represent the groups of 26 pairs of wires after random lays have been produced therein by the oscillating units 14. The random lay groups 15 are directed to a stationary unit 1.6v where: they are received in their respective spaced positions through a. face plate (not shown) and are twist-ed together through the action of a take-up unit 17. The take-up unit 17 supports a reel 18 which is driven by a mechanism 19 to wind the cable core 11 thereon while at the same time the housing 20 for the take-up unit is rotated by a motor drive 21 to produce the desired twist of the random lay groups of wires in the cable core.

The novel feature of the cable is thepresence of random group lay therein and the feature of the apparatus: for producing this result is the individual driving of the uni-ts 14 by direct current motors. In FIG. 3 the unit 14 includes a main member 22 supported by bearings 23 and having its entrance end 24 flared outwardly and recessed to receive a face plate 27. The face plate 27 has, in the present instance, twenty-six bushing-like guides 28' for the twenty-six pairs of wires 12 received from the supplies 10-. The exit end of the main member 22 has a sleeve 29 mounted therein, removably held in place by a thumb screw 30. A forming die 31 mounted in the sleeve 29 has an outwardly flared entrance end 32 to receive the pairs of wires 12 and form them into a circular group. The bearings 23 are supported in a housing 34' mounted on a support 35. The housing 34 carries a spindle 36 for an idler sprocket 37. A sprocket 38 is secured to the exit end of the main member 22 and is connected by a chain 39 to a sprocket 40: on an output shaft 41 of a speed reducing unit 42. A direct current motor 43 drives the speed reducing unit 42 to drive, through the intermediate connecting means, the face plate 27. The box type structure 45 represents a suitable means for binding the group of wires 15 together. This structure is not shown in detail as it per se is not a part of the present invention. A suitable roller 46 is positioned at the exit end of this structure to guide its respective group of wires to the unit 16.

In one embodiment of the invention, as illustrated schematically in FIG. 1, there are 16 of the units 14, shown in detail in FIG. 3. These units may be identical in structure, with the exception of the motors 43, furthermore, the motors may be commercially identical units made to the same specifications and nearly alike as possible. As is well known, however, a group of such motors driven from the same power source will not operate at exactly the same speeds nor will they respond in exactly the same way to variations in load. The power required to drive the various face plates will not be exactly the same and will vary slightly from time to time. Hence, for these and other reasons the several face plates will be oscillated at slightly different rates. The relative orientation of the several face plates Will therefore be changing constantly and due to the many factors determining their oscillation rates the distribution of the wire pairs in the cable will vary in a random manner.

The wiring diagram shown in FIG. 2 is a fragmentary portion of the entire wiring arrangement for the 16 motors in that only a portion for two of the motors is shown. Lines 50 and 51 supply the direct current energy for motors 43-A and 43-B and their

respective field windings

52 and 53. The field windings of all of the motors are connected to lines 51 through a variable resistance 54. The 'arrnatures of all of the motors are connected to the supply lines 50 through reversing contactors 55 operated by a single switch 56 on each unit 14. In FIG. 3 the switch 56 is mounted for engagement with and actuation by removable screws 57 and 58, mounted in the main member 22 of the oscillating unit. Their functions, as a result of their spaced positions from each other are to determine the degree of oscillation of the unit 14. In the present illustration they are disposed 180 apart assuring 180 oscillation of each unit. Other adjustments may be made by varying the relative posi tions of the screws 57 and 58.

Considering the operation of the apparatus to produce the'cable with the random group lay, let it be assumed that all of the operating units of the apparatus have been rendered effective, including the take-up 17, to advance the completed cable core 11 on to the take-up reel 18 and that the motors 43 have been energized. Regardless of the positions of the switch actuating screws 57 and 58 with respect to the switches 56 at the time the motors 43 are energized, the differences inherent in the operating characteristics of the direct current motors 43 will produce oscillation of the units 14 at slightly ditferent speeds to produce a continuous change in the formation of the lays of the groups of wires. If, for example, the units 14 were all in the position shown in FIG. 3 where the screw 57 is ready to reverse the switch 56 to cause reversal in the switches 55 for all of the motors 46 at the beginning of the cable forming operation, before the screw 58 of any one of the units operates its switch 56 there will be a variation in the positions of these screws 58 with re spect to their switches 56 due to the differences in the speeds of their motors 43. These differences need be only very slight since they are cumulative and the initial cross-sectional arrangement of pairs begins to change immediately in a non-repetitive manner so that no two successive cross-sections of the cable are identical.

A typical cross-section of the cable is shown in FIG. 5. One pair of wires is shown in each unit to indicate the orientation of the unit and the instantaneous direction of oscillation of each unit is indicated. If another section is taken along the cable even at a point where all the face plates are rotating in the same directions as before the orientation of the various units will be differcut as indicated in FIG. 6, and the pairs in adjacent units which formerly were close together in inductive relation will be relatively remote from each other. With this constant shifting in the relative positions of the various pairs in different units the inductive difficulties between pairs of different units are substantially balanced out.

If wider variations in the random lays in the groups of wires are required variable resistance unit 60 may be disposed in the motor circuits and set at difierent values to increase the inherent ditferences in the motor speeds as required.

One of the important advantages of the present invention is that by making it possible to form a complete cable in one operation, all of the former expense incident to the use of a number of the difierent types of units is entirely eliminated.

It is to be understood that the above described arrangements are simply illustrative of the application 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 spirit and scope thereof.

What is claimed is:

1. A multi-unit cable formed of a plurality of cable units bound together, the cable units having groups of twisted pairs of wires and the groups of pairs of wires in each unit being twisted together in a relative orientation which varies in a non-repetitive manner between the units throughout the length of the cable.

2. A multi-unit cable formed of a plurality of cable units bound together, the cable units having groups of twisted pairs of wires and the groups of pairs of wires in each unit having back-and-forth random twists causing relative orientation of the pairs of wires of the groups in the units to vary in a non-repetitive manner between the units throughout the length of the cable, and individual bindings for the cable units to retain the random twists of their groups of pairs of wires.

References Cited in the file of this patent UNITED STATES PATENTS 491,109 Holman Feb. 7, 1893 502,262 Patterson July 25, 1893 1,795,209 Haugwitz r Mar. 3, 1931 1,854,795 Kaempf Apr. 19, 1932 2,038,240 Schelkunofi Apr. 21, 1936 2,869,316 Lilly Jan. 20, 1959