US2404782A - Assembling apparatus - Google Patents

Description

G. E. BERGGREN ETAL 2,404,782

July 30, 1946,

AS S EMBLING APPARATUS 3 Sheets-Sheet l i Filed Nov. 50, 1944 ERGGWEN V 1 ERML AN ATTORNEY I J y 1946- G. E. BElGGREN ET AL 2,

ASSEMBLING APPARATUS Filed Nov. 50, 1944 5 Sheets-Sheet 5 F /C 8 mxvavroes 85 86 as BEEGGREN A Lo AN 8) TTORMEY Patented July 30, 1946 UNITED STATES PATENT OFFICE ASSEMBLING APPARATUS New York Application November 30, 1944, Serial No. 565,840

(Cl. 292t0) 6 Claims. 1

This invention relates to assembling apparatus and more particularly to apparatus for assembling annular insulating and spacing discs on a central conductor used in making coaxial cables.

This application is a continuation-in-part of copending application, Serial No. 470,746, filed December 31, 1942.

Coaxial cables usually comprise a solid central conductor and a tubular outer conductor, which is held away from and maintained coaxially of the central conductor by means of waferlike spacing and insulating discs. Such cables have been made in the past by stringing insulating discs having central apertures therethrough upon the central conductor, much in the same manner that beads are strung upon a strand, and then forming the tubular outer conductor over the discs in any suitable manner. It also has been suggested that the discs be molded directly upon the central conductor, but this method requires complicated and expensive apparatus.

Another method of making these cables that has been used heretofore was to punch a number of insulating discs from a strip of suitable material, such as hard rubber, in a punch press having a punch and die of such configurationthat the discs had central apertures for receiving the central conductor and radial slots extending from the central openings to the periphcries of the discs through which the central conductor was forced into the central openings. Usually the radial slots had constricted portions, and the discs were sufficiently resilient to permit the slots to open up as the central conductor passed through the constricted portions and to snap back around the conductor after the conductor had entered the central apertures in the discs. As a result, the discs engaged the central conductor firmly and could not be displaced readily.

Polystyrene has been suggested as a suitable material to use in making the insulating discs, but pure polystyrene is so brittle that slotted discs made therefrom cannot be applied to central conductors without breaking the discs. Hence, when polystyrene discs are used they must be threaded or molded upon central conductors. It is obvious that when long, con tinuous central conductors are employed, it is impractical to thread centrally perforated discs upon such conductors, while apparatus for con tinuously molding discs upon such central conductors is costly and complicated.

The application of slotted discs to central conductors may be performed with satisfactory results when the discs are made of a relatively hard, resilient material, such as hard rubber, but this method is unsatisfactory when discs made of soft plastics are employed.

One of the plastic materials, which has properties that render insulating discs made therefrom especially suitable for use in the manufacture of coaxial cables, is the one obtained by polymerizing ethylene. This material, which is called polyethylene, is a moderately soft, pliable material, having a high molecular weight and possessing excellent insulating characteristics. This material may be obtained from several sources, one of which is E. I. Du Pont ole Nemours & Company, which sells it under the trade name Polythene.

Polyethylene is sufficiently hard to permit insulating discs made therefrom to maintain their shapes under ordinary circumstances, but it is soft enough to cause some manufacturing difficulties to arise when slotted discs are punched from strips thereof, Furthermore, when slotted discs of the type formerly made of hard rubber were made of polyethylene and were forced upon a central conductor, the sides of the slots occasionally were deformed by the passage of the conductor therethrough. As a result, the discs would not adhere firmly to the central conductor, and would tend to slide along the conductor or might even come off the conductor. In addition, it is relatively easy to force such discs on the conductor by a thrust applied on the sides of the discs opposite the slots and substantially longitudinally of the conductor, because the small amount of the material in the Walls of the slots against which the conductor presses under those circumstances does not possess enough sheer strength to hold the discs in place.

An object of the invention is the provision of simple and effective apparatus for assembling articles.

An apparatus embodying the invention operates as follows: a single hopper feeds annular insulating discs through two sets of separate feed paths to a pair of feed wheels, which carry the discs past knives to cut a radial slit in each annular disc and which alternately slide the discs upon a constantly moving central conductor with a wiping motion, the slits in the discs being held slightly openand maintained in the slots in the feed wheels by means of retus for applying annular insulating and spacing .discs to a central conductor, which apparatus embodies the apparatus of the present invention and provides means by which the present invention may be practiced;

Fig. 2 is an enlarged, fragmentary, detailed sectional view taken substantially along the line 2-2 of Fig. l in the direction of the arrows;

Fig. 3 is an enlarged, fragmentary, sectional View taken substantially along the line 3-3 of Fig. 1 in the direction of the arrows;

Fig. 4 is a fragmentary, sectional view taken substantially along the line 4-4 of Fig. 3 in the direction of the arrows and showing details of one of the feed wheels and its co-operating parts;

Fig. 5 is a'greatly enlarged detailed View in section taken substantially along the line 5-5 of Fig. 4 in the direction of the arrows and showing an insulating disc being carried by a feed wheel, together with the retainer provided for holding the discs on the feed wheel and for holding open the slits in the discs;

Fig. 6 is a fragmentary plan view, partly in section, of the hopper and its communicating disccarrying mechanisms for directing the annular discs to the feed wheels;

Fig. 7 is an enlarged, fragmentary, vertical, sectional view taken substantially along the line 1-1 of Fig. 6 in the direction of the arrows;

Fig. 8 is a detailed, elevational View showing a knife for slitting the insulating discs;

Fig. 9 is an enlarged, fragmentary perspective view'of the blade end of the knife shown in Fig. 7 and illustrating how the knife cuts slits in the annular discs;

Fig. 10 is a detailed view showing one of the annular discs before it is slitted;

Fig. 11 is a cross-sectional view of a coaxial cable utilizing the unit comprising the central conductor and insulating discs assembled in accordance with the present invention, and

Fig. 12 is a view in perspective of a short length of coaxial cable, which utilizes the unit formed in accordance with the present invention, part of the tubular outer conductor being broken away to illustrate the positioning of the insulating and spacing discs between the tubular outer conductor and the central conductor.

Referring to the drawings, wherein like reference characters designate the same parts throughout the several views, a main support member [5 is provided for supporting a hopper designated generally by the numeral 16, feed wheels I! and I8 and transfer devices designated generally by the numerals l9 and 20. The hopper l5 and the transferdevice 9 are interconnected by a-guide designated generally by the numeral 2| and the hopper l6 and transfer device are interconnected by a guide designated generally by the numeral 22. The details of the hopper l6 are shown most clearly in Figs. 6 and 7 and, by reference to these figures, it will be seen that the hopper includes an inverted cone-shaped bin 23, into whichannular discs may be dropped haphazardly. The bin 23 terminates at its lower end in an annular member 24 surrounding a substantially cone-shaped agitator 25. The agitator 25 may be rotated within the annular member 24 in any suitable manner, for example, by a motor (not shown) driving a transmission or gear reducing unit 26, which also supplies power to drive a pair of shafts 21 and 28 on which the feed wheels H and I8 are mounted. This driving connection may be of any suitable construction and, since the details thereof are not pertinent to the present invention, they have not been described in great detail.

Extending upwardly from the unit 26 is a shaft 29, on which the cone 25 is supported for rotation within the bin 23. The cone 25 is provided with a flattened cylindrical lower end 30, which, together with the bin 23, defines an annular slot 3| into which annular discs 32-32, as shown in Fig. 7, may drop when the agitator 25 is rotated within the bin 23. Fixed to diametrically opposed surfaces of the agitator 25 area pair of feed fingers 33 and 34 made of steel wire and bent to extend into the annular slot 3| formed by the annular member 24 and the flattened lower surface of the agitator 25, whereby any discs which drop into the slot move around in the slot as the agitator 25 rotates. The feed fingers 33 and 34 are sufficiently resilient so that if the guides 2| and 22 are filled with discs, the feed fingers'will bend and pass over the tops of those discs in the slot 3 I.

At opposite sides of the annular member 24, there are provided means for directing discs 32-32 from the slot 3| into the guides 2| and 22 and these devices comprise support plates 4|] and 4| fixed to the annular member 24 and carrying assemblies 42 and 43, respectively, for directing the discs into the guides 2| and 22. Both of the assemblies 42 and 43 are of exactly the same construction and, accordingly, only the assembly 42 will be described in detail. The assembly 42 comprises two plates 44 and 45 suitably fixed together iri abutting relation. The plate 45 has a groove 46 formed therein which, when the assembly 42 is mounted in place, as shown in Figs. 6 and 7, comprises a tangential prolongation of the annular slot 3|. The groove 46 cooperates with the flat surface of the plate 44 to form a passageway into which the discs 32-32 will be directed by an extending finger 45, which is formed integrally with the plate 45 and extends into an annular slot 48 formed on the flat lower surface of the cone-shaped agitator 25. The finger 41 serves to strip the discs out of the slot 3| and guide them into the groove 46. The annular member 25 is cut away, as shown at 49 and 50, to receive the plates 44 and 45 so that the plates 44 and 45 will cooperate to guide the discs into the guides 2| and 22.

The guides 2| and 22 are of the same general construction except that they are bent at different angles for guiding the discs 32-32 fed therein from opposite sides of the hopper I6. Each of the guides 2| and 22 comprises, as shown most clearly in Fig. 2, a strip 5| having a slot 52 cut therein, in which the discs 32-32 will drop. At-

tached to the strip 5| is a thin plate 53, which,

partially closes the slot 52 and will serve to retain the discs in position therein while they are guided down from the hopper to the transfer devices I9 and 20. A slit between the plate 52 and strip 5| permits visual inspection of the supply of discs 32-32 in the guides and, if desired, air blasts may be directed against the discs to insure that they move down the guides.

At the transfer devices 19 and 23, the guides 2| and 22 terminate in a transfer block 60, which has a slot 6| formed therein, which slot comprises a prolongation of the slot .52 in the strip 5|. The slot 61 is in communication with a plunger slot 62, in which a plunger 63 is slidably mounted. The plunger 533 is mounted upon a connecting member 64, which is formed integrally with a cam projection 65, A spring 56 normally urges the camming projection 65 and connecting member 64 to the left, as seen in Fig. 2, to carry the camming projection 5.5 into engagement with a cam 61. The cam 57 is mounted upon the shaft 28 and is positioned in back of the main support member l5. The shaft 25 also carries a gear 63 in mesh with a gear 59 fixed to the shaft .2! and the shaft 2'! also carries a cam member 153 of exactly the same construction as the cam 61. Thus, the construction is the same for both transfer devices [9 and 20.

A plate 1'! 8 fixed to the main support member l5 serves as a guide for the connecting member 64 and the main support member I5 is provided with a suitable aperture '22, which permits the connecting member 64 and camming projection 65 to reciprocate in a guide slot 73 formed in the plate ll. Each time the camming projection .65 strikes a low point on the .cam 6 one of the discs 32-32 will be transferred from the slot 6| into the feed wheel l8, which is provided with a series of notches i l-M for receiving the discs It should be noted that the notches 74-74 alternate with notches iii-i5 around the periphery of the feed wheel l8 and that the notches '55-'55 have one surface cut awa for a purpose to b described i hereinafter.

As the feed wheel i8 rotates, an annular disc 32 will be fed into each of the notches Hi-H. cut therein and will be carried around with the feed wheel I13. Just below the position where the feed wheel !8 receives the annular discs 32-3-2, there is provided a knife l6 (Figs, 4, 8 and 9), which will cut a radial slit 7'! (Figs. 9, 11 and 12) in each disc as the di cs are carried past the knife. Extending peripherally of the feed wheel lBin direct vertical alignment with the knife i5 is a retainer l5, with which the slit l! in each annular disc will engage and with which the edge of the central aperture iii of each disc will engage (Figs. 4 and 5), whereby the disc 32-52 will be forced to travel aronndwith the feed wheel IS. The retainer 18 extends to a position Where it is engaged on its upper edge by a central conductor 85, on which the discs 32-32 are to be assembled. The retainer 73 has the same thickness as the bottom portion of the knife l5 and the discs which are slit by the knife pass directly from the knife onto the retainer. The retainer holds the slits formed in the discs slightly open until the discs reach the central conductor 80, which permits the central conductor to slid -freely into and through the slits into the central apertures Iii-l2 in the discs.

The central conductor 88 is fed through a guide 8|, which cooperates with other guides and feed mechanisms (not shown) for guiding the conductor past the feed Wheels I1 and I8 in timed relation to the rotation of the feed wheels. The construction of the slitting mechanism at the transfer device 29 is exactly the sameas at the transfer device l9, lf'here is provided a knife similar to the knife '56 for slitting the discs radially and a retainer 82 similar to the retainer 18, but shorter than the retainer 13, for guiding those discs 32-32 which are fed to the feed wheel I! 6 to a position where the discs will be forced onto the central conductor 80 and. for holding open the slits in the discs until they reach the central conductor. The feed wheel H is provided with notches 14-14 and -15 alternately about its periphery in the same manner as is the disc is, since it is desired to apply the discs 32-32 from opposite sides of the central conductor 82. When a tubular outer conductor'83 is applied around the discs 32-32 co-axially with the central conductor 853, the discs 32-32 will hold the tubular outer conductor spaced an equal distance from the central conductor 89 throughout the length of the cable and will insulate th two coaxial conductors from each other.

As is evident from Figs. 8 and 9, each of the knives illustrated by the knife 76 comprises a flat shank 88 having a head 84 formed at the end thereof adjacent to its companion feed wheel.

The bead 84. has a raised point 65 at the top 1 thereof designed to cause the bead to enter the central apertures 12-79 of the discs 32-32 so that a curved cutting edge 86, which is formed at the upper edge of the shank and extends from the point 8 5 to a point on the shank beyond the outer edges of the discs, may cut a radial slit 7'! in each disc a the discs 32-32 are carried past the knives by the feed wheels.

Since the discs 32-32 are applied to the central conduct-or from opposite sides, the notches 14-14, which carry the discs 32-32 on both of the feed wheels I! and I8, are arranged so that when one of the discs 32-32 is forced onto the central conductor 80 b the feed wheel l8, one of the notches 15-15 in the feed wheel I! will receive the upper end of the disc. Likewise, when the feed wheel I1 carrying a disc 32 in one of its notches i l-l4 reaches the position where the disc is to be forced onto the central conductor, the notch Min the feed Wheel I! which carries the disc will be in alignment with a notch 15 on the feed wheel l8 and the latter notch will receive the disc.

In the operation of the present machine a supply of annular insulating and spacing discs 32-32 may be thrown haphazardly in the hopper ts, from which they will be fed by the feed fingers 34 and 35 into the guides 2i and 22. As the discs 32-32 ar fed into the guides, they will travel down the guides to the transfer devices I9 and 23 and the cams l5! and H1, operating in timed relation with each other, will transfer the discs into th notches 14-14 of the feed wheel I! and 13. As the discs are carried around by the feed wheels H and [8, they will be drawn past the knives, illustrated by the knife l6, and a radial slit will be cut in each discby the knives, The slitted discs will then be carried around by the feed Wheels ii and I2, being held in the notches Id-i4 by the retainers 82 and 78, until the slitted discs are forced onto the central conductor 85 travelling from left to right as seen in Fig. 1. After the discs 32-32 are thus applied to the central conductor 89. the tubular outer conductor 83 may be applied over the discs in any suitable manner.

As is apparent from Figs. 4 and 5, the retainers l3 and 82 maintain the slits ll-Tl in the discs 32-32 slightly open from the time the slits are cut therein by the knives until the discs reach the central conductor 89 upon which they are applied. This permits the central conductor 59 to enter the slits readily and to slide easily through the slits into the central apertures ls-l9 of the discs. The discs 32-32 are carried toward the central conductor by the feed wheels l1 and 18 along arcuate paths and, consequently, the discs are forced upon the central conductor with a wiping motion. In view of the fact that the slits H are held slightly open by the retainers l8 and 82 until the discs reach the central conductor 80 and also because the discs are applied to the central conductor with a wiping motion, no injury results to the forward corners and sides of the slits, such as might occur if the slits were permitted to close before they reach the central conductor and were forcibly opened by the passage of the central conductor therethrough. This is especially important when the insulating discs are made of relatively soft materials, such as polyethylene.

Since the retainers l8 and 82 end at a point adjacent to thecentral conductor 80, the slits are released as the discs are applied to the central conductor and are free to close after the discs have been placed upon the central conductor. As a result, the slits tend to close up and the discs substantially completely surround the central conductor, somewhat in the manner illustrated in Figs. 11 and 12, thereby insuring the retention of the discs in their proper places upon the central conductor.

The central apertures 19-19 in the discs 3232 are slightly smaller in diameter than is the central conductor Bil. As a result, the central conductor tends to spread open the slits ll'll in the discs, as is shown in Fig. 12, and the natural resiliency of the discs causes the discs to engage the central conductor firmly. After the tubular outer conductor has been applied over the unit formed by the central conductor and a series of discs applied thereto, the slits in the discs are substantially closed, as shown in Fig. 11, and then there is practically no possibility that the discs will slide along the central conductor.

The apparatus outlined hereinabove obviates the problems that would arise if an attempt were made to slit the discs at the time the are formed, to feed the slitted discs from a hopper into a pair of mechanisms with the slits orientated and to advance the discs through the mechanisms to the applicator Wheels. Likewise, deformation of the walls of the slits is prevented and the discs so applied to a central conductor engage the conductor firmly. It is diflicult to purposely remove discs thus applied to the conductor, much less to remove them accidently, because the slits tend to close up around the conductor and the conductor is engaged by a substantially solid ring of insulating material, such as is illustrated in Figs. 11 and 12 of the drawings. It is obvious that the location of the slitting step is important and that this invention provides a simple yet elTective apparatus for assembling articles, particularly apparatus for the application of insulating discs to central conductors to form units suitable for use in the manufacture of coaxial cables.

While the insulating discs 32 32 preferably are made of polyethylene, the apparatus embodying the invention may be used equally well to apply discs made of other relatively soft insulating materials to central conductors. For example, the insulating discs may be made of cellulose acetate or mixtures of cellulose acetate and cellulose butyrate, or may be fabricated from relatively soft products obtained by polymerizing vinyl compounds, such as are obtained by polymerizing vinyl chloride and vinyl acetate or mixtures thereof.

What is claimed is:

1. In an apparatus for applying soft annular discs to a conductor, means for feeding a plurality of such discs along a predetermined path and to a conductor, and means adjacent to said path including means for cutting each of the annular discs advanced therealong to form discontinuous annuli, means passing through the resulting cuts in the discs for expanding the cuts and means entering the expanded cuts for maintaining them expanded, said last mentioned means extending to the conductor, whereby the conductor slides freely through the expanded cuts without damaging the discs.

2. An apparatus for use in applying soft annular discs to a conductor, comprising a guide for receiving slitted discs along one side thereof and for guiding the discs to a conductor, the guide being thinner than the diameter of the conductor and being received in the slits in the discs to hold them open, and means in advance of the guide for forming slits in the discs which have a gap no wider than the thickness of the guide, said slitting means including means for expanding the slits in the discs and while the slits are expanded guiding the discs to the guide.

3. An apparatus for applying soft annular insulating discs upon a conductor, which comprises a rotatable feed wheel for advancing such discs to and forcing them upon the conductor, means for cutting slits in the discs carried by the feed wheel and for expanding the slits, and means adjacent to the slit-cutting means for entering the expanded slits in the discs and for maintaining the slits expanded until the discs are advanced to theconductor.

4. An apparatus for applying soft annular insulating discs upon a conductor, which comprises means for longitudinally advancing the conductor, a rotatable feed wheel for advancing such discs to and forcing them upon the movingconductor, a knife adjacent to the feed wheel and in the path of discs carried by the feed wheel for cutting radial slits in the discs and for expanding the slits, and an arcuate retainer adjacent to the knife and in alignment therewith for entering the expanded slits and keeping them expanded until the discs reach the conductor. J

5. In an apparatus for applying soft annular insulating discs upon a conductor, means for advancing a plurality of such discs along a predetermined path to the conductor, a knife extending into said path for cutting radial slits in the discs advanced therealong, said knife having a cutting edge of reduced thickness on the side thereof first engaged by the discs and expanding to a greater thickness at the edge where the discs leave the knife, and a guide abutting the exit edge of the knife for entering the slits cut in the discs as the discs leave the knife to prevent the slits from closing, said guide extending to the conductor.

6. An apparatus for applying soft annular insulating discs to a conductor, which comprises means for advancing a conductor longitudinally,

rotatable feed wheels fOr carrying such discs to opposite sides of the conductor and forcing them upon the conductor, means for feeding the discs to the feed wheels, a knife associated with each feed wheel and positioned in the path of the discs carried by its associated feed wheel for cutting radial slits in said discs, each of said knives having a cutting edge of reduced thickness on the V e 10 Side th re f first en a ed y the discs and exfrom closing and extending to a point close to panding to a greater thickness at the edge where the conductor, whereby the conductor slides freethe discs leave the knife, and an arcuate retainer 1y through the slits Without damaging the discs. adjacent to each feed Wheel and abutting the exit edge of the associated knife, each of said GEORGE E. BERGGREN. guides entering the slits cut in the discs as the EDWARD BERTALAN. discs leave the adjacent knife to prevent the slits ALEXANDER LOGAN.

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