US2579487A - Method of and apparatus for feeding and applying insulating disks to conductors - Google Patents

Description

' A. c. FRANKWICH METHOD OF AND APPARATUS FOR FEEDING AND Dec. 25, 1951 2,579,487

' APPLYING INSULATING DISKS TO CONDUCTORS 2 Sl-IEETS-Sl-EET 1 Filed Oct. 10, 1946- INVENTOR AC. FRAN/(W/CH ATTORNEY Dec. 25, 1951 Filed 001;. 10, 1946 A. C. FRANKWICH METHOD OF AND APPARATUS FOR FEEDING AND APPLYING INSULATING DISKS TO CONDUCTORS 2 SHEETSSHEET 2 1J0 I V 30 FIG. 2

wvmrok A. c. FRANKW/CH ATTORNEY Patented Dec. 25, 1951 METHOD OF AND APPARATUS FOR FEEDING AND APPLYING INSULATING .DISKS 'IO CONDUCTQRS Alexander (J. Frankwich, Baltimore, Md., assignor to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application October 10, 1946, Serial No. 702,494

8 Claims. (o1..29 155.5)'

This invention relates to methods of and apparatus for feeding and applying insulating discs to conductors, and more particularly to methods of and apparatus for expanding slits in plastic insulating discs to facilitate application of the discs to conductors.

In some types of apparatus for forming coaxial cable core units of a type having washerlike, plastic insulating discs positioned on a central conductor, the insulating discs are slit radiallyand are wiped onto a conductor, the conductor passing through the slits into the central openings in the discs. In the past, in order for the conductor to pass through the slits, the slits have been expanded by a wedging action of the conductor thereon as the slits are wiped thereover. When the slits in the discs are expanded by the conductor, they are expanded abruptly, and as aresult, the discsare sometimes damaged physically. Furthermore, if the conductor has loose particles of conductive material on the surface thereof, the walls of the slits in the insulating discs sometimes carry away the conductive particles as they are wiped onto the conductor. The conductive particles reduce the dielectric strength of the insulating discs along the slits thereof, and sometimes cause dielectric breakdowns in the discs. The dielectric strength of the discs applied to the conductor is tested, and if any of the discs are defective, the entire cable forming apparatus must be stopped in order to replace the defective discs with nondefective discs. 7

1 An object of the invention is to provide new and improved methods of and apparatus for feed ing and applying insulating discs to conductors.

-A further object of the invention is to provide new and improved methods of and apparatus for expanding slits in plastic insulating discs so that, when the discs are wiped onto a conductor, at least the major portions of the walls of the slits are held out of contact with the conductor and pressure on the discs by the conductor and contamination of the walls of the slits in the discs by foreign particles on the conductor are minimized.

In a method illustrative of the invention, a washer-like, plastic insulating disc having a radial slit therein extending from the outer periphery thereof to the central aperture thereof is moved through a predetermined path to a conductor. As the disc approaches the conductor, the slit is expanded, and the disc is moved onto the conductor. 7 .The expansion of the slit is sufficiently gradual that. the. disc-is not mechanically damaged thereby. The width of the expanded slit is such that for the most part, the walls of the slit do not contact the conductor as the disc is moved onto the conductor.

An apparatus illustrative of the invention inciudes an applicator wheel having a plurality of notches therein for carrying washer-like insulating discs and for applying the insulating discs to a conductor. A knife slits the discs carried by the applicator Wheel so that the. discs may be wiped onto the conductor and an expander positioned near the point of application of the discs to the conductor serves to expand'the discs as the discs are wiped onto the conductor by the applicator wheel. The expander opens the slits in the discs in such manner that the discs are not crushed and opens the slits sufiiciently to insure that the major portions of the walls of the slits do notcontact the conductor as the discs are wipedcnto the conductor, whereby contamination of the walls of the slits is avoided.

Fig. 1, and I r Fig. 5 is an enlarged, fragmentary, substantially vertical section taken along line 5-5 of Fig. 1.

Referring now in detail to the-drawings, there is shown in Fig.1 an apparatus for feeding, slitting and applying washer-like, plastic insulating discs it-lll composed of a dielectric material, such as, for example polyethylene, to a conductor H to form a core unit of a coaxial cable. The complete apparatus is described and claimed in copending application, Serial No. 702,491, filed October 10, 1946 byv S. E. Brillhart. .The discs Ill-l0 are fed to straight, vertical guide chutes l2 and I3 by a hopper feed I5 certain features of which are described and claimed in my copending application, Serial No. 702,493, filed October 10,1946. The guide chutes I2 and i3 feed the. discs by gravity to transfer devices it and I1,

respectively. which feed the discs into notches 2020 and 2|2| formed in inrunning applicator wheels 22 and 28, respectively. The applicator wheels 22 and 23 move the discs over knives 26 and 21, respectively, which form line-like radial slits 28-28 in the discs.

The applicator wheels 22 and 23 move the discs Ill-I along thin arcuate guides 30 and 3|, respectively, extending from the knives 26 and 21, respectively, and along expanders 32 and 33, re-

spectively, and apply the discs to the conductor II, which enters the holes in the discs through the slits 28-28 formed therein. The thin arouate guides 30 and 3| form continuations of the knives 26 and 21 and enter the slits 28-28 immediately after they are formed. The guides hold the discs Ill-Ill slightly open and in oriented positions as the discs. are moved by the ap licator wheels 20 and 2| toward the conductor II, in which positions the slits are directed radially with respect to the applicator wheels.

The wedge- shaped expanders 32 and 33 are identical, and for purposes of simplicity, only the expander 32 will be described in detail. One end 40 (Fig. 3) of the expander 32 is the same thickness as and abuts an end of the arcuate guide 30 so that the expander engages the walls of the slits 28-28 as the discs are moved therealong. The expander 32 gradually increases in thickness to the opposite end 4| thereof.

As the discs Ill-l0 are moved along the expander 32, the expander 32 gradually opens the slits 28-48 therein, and as outside corners 4545 (Fig. 5) .of the slits start to pass over the conductor ll, these corners are held suiiiciently far apart to insure that they do not contact the conductor I. As the discs are moved further along the expander 32, the slits 2B28 are expanded still more in order that most of the surfaces of walls 46-46 of the slits will not contact the conductor and cannot be contaminated thereby. When the discs are almost on the conductor, they are moved off the end 4| (Fig. 3) of the expander 32 and the portions of the walls 46-46 of the slits near inside corners 4'|4| of the slits contact the conductor. At this point, the slits are opened almost sufiiciently for the corners 414'| to move over the conductor and hold the outer portions of the walls 4646 out of contact with the conductor. The applicator wheel 22 then wipes the inside corners 41- 41 of the slits overcenter on the conductor and the discs snap into place thereon.

The expanders 32 and 33 are mounted on a conductor guide 50, and guide the conductor H therebetween. The applicator wheels 22 and 23 support the conductor passing therebetween as the discs |0|0 are applied to the conductor alternately by the wheels.

In the method and apparatus described hereinabove, the discs ||l--l0 are moved along the long. thin guides 30 and 3| which keep the discs oriented but keep the slits 28--28 in the discs only slightly open so that no permanent deformation of the discs occurs from the travel of the discs along the long guides 30 and 3|. The discs then are moved over the relatively short expanders 32 and 33 which are sufliciently long to open the slits gradually enough to prevent crushing the discs, but which are short enough that no permanent deformation of the discs is caused by the'expanders.

The expanders 32 and 33 expand the slits relatively slowly and sufiiciently to cause the conductor I to expand the slits only a small amount further as the final stages of the application of the discs to the conductor are effected. Hence,

the discs are not bent or crushed as they might be if they were forced over the conductor without preexpansion of the slits therein. Also, if the conductor has any loose conductive particles on the periphery thereof, the particles are not pressed against the walls 46-46 of the slits 28-28 to form conductive paths, except for theportions of the walls adjacent to the inside corners 4'|4| of the slits. Hence, contamination which might cause dielectric breakdown of the discs is minimized.

The above-describedmethod and apparatus are particularly advantageous in feeding and applying discs composed of polyethylene to conductors. Such discs, while sufficiently hard to have the necessary mechanical properties if placed on the conductor undamaged, are soft enough that they were sometimes damaged as they were placed on conductors by ordinary methods and apparatus. In the method and apparatus described hereinabove, the discs are placedon the conductor without permanently deforming the discs and without crushing the discs. Hence, the discs adhere firmly to the conductor, and do not slide along the conductor after they have been applied thereto.

What is claimed is:

1. The method of feeding and applying insulating discs to conductors, which comprises moving through a predetermined path to and onto a conductor a washer-like insulating disc having an inner periphery, an outer periphery and an opening extending from the outer periphery thereof to the inner periphery thereof, and gradually expanding the opening as the disc approaches the conductor and is moved onto the conductor to prevent abrupt expansion of the opening as the disc is moved onto the conductor.

2. The method of feeding and applying insulating discs to conductors, which comprises moving a discontinuous annulus through a predetermined path onto a conductor in a manner in which the ends of the annulus are moved over the conductor, the distance between the ends of the annulus being less than the diameter of the conductor, and moving the ends of the annulus apart as they are moved over the conductor sufilciently to prevent contact between the conductor and at least the major portions of the ends of the annulus.

3. The method of feeding and applying insulating discs to conductors, which comprises moving toward and onto a conductor a washer-like, soft, plastic insulating disc having a slit therein extending from an outer periphery of the disc to an inner periphery thereof, and gradually expanding the slit in the disc as it is moved toward and onto the conductor to restrict permanent deformation of the slit by the conductor as the disc is moved onto the conductor.

4. The method of feeding and applying insulating discs to conductors, which comprises moving transversely toward and onto a conductor an insulating disc having a slit therein, the slit in the disc moving over the conductor as the disc is moved onto the conductor, expanding the slit gradually as the disc is moved toward the conductor, and further expanding the slit substantially without the aid of the conductor as the disc is moved onto the conductor.

5. The method of feeding and applying insulating discs to conductors, which comprises moving an annular insulating disc facewise through a predetermined arcuate path toward a conductor positioned at the end of the path and tangent to the path, radially slitting the portion of the annular disc moving through the outer portion of the path as the disc is moved toward the conductor, gradually wedging open the slit in the disc as the disc is moved toward the conductor to an extent that the walls of the slit in the disc are held substantially out of contact with the conductor as the disc is moved to the end of the path.

6. In an apparatus for feeding and applying 10 insulating discs to conductors including an applicator wheel for moving an annular, plastic insulatin disc through a predetermined path and for applying the disc to a conductor being advanced tangentially with respect to the ap- 1 plicator wheel, a knife for slitting the disc radially at a predetermined point in the path of the disc and a thin arcuate guide adjacent to the lmife for entering the slit to keep it open and to guide the disc, the improvement which com- 2 prises an expander positioned to enter the slit in the disc and extending from the guide substantially to the conductor, said expander being tapered outwardly from the end thereof adjacent to the guide to the other end of the expander and serving to gradually open the slit in the disc as the disc is moved over the expander, the portion of the expander near the conductor being suificiently thick to maintain the walls of the slit out of contact with the conductor during at 30 least a portion of the movement of the discs over the conductor.

7. In an apparatus for feeding and applying annular, radially slit, plastic insulating discs to conductors including an applicator wheel for moving such a disc through a predetermined path and for applying the disc to a conductor being advanced tangentially with respect to the applicator wheel and a knife for slitting the disc, the improvement which comprises an expander extending arcuately along the outer periphery of the applicator wheel from a point spaced from the conductor to the conductor, said expander being tapered from a thin end at the point Spaced from the conductor to a thicker end at the conjductor, whereby the slit in the insulating disc 5 is expanded as the disc is moved along the ex- I predetermined point in the path of the disc and a thin arcuate guide adjacent to the knife for 0 entering the slit to guide the disc and to hold open the slit therein, the improvement which comprises a wedge-shaped expander positioned enter the slit in the disc and extending arcuately from the guide substantially to the 5 conductor, said expander being thin near the arcuate guide and being thicker near the conductor and serving to expand the slit in the disc to such an extent that the walls of the slit are kept substantially out of contact with the conductor as the disc is applied to the conductor.

ALEXANDER C. FRANKWICH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,669,053 Hamel May 8, 1928 2,045,087 Keller et a1 June 23, 1936 2,404,782 Berggrcn et a1 July 30, 1946 2,426,623 Larsen Sept. 2, 1947

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