|Publication number||US2501481 A|
|Publication date||Mar 21, 1950|
|Filing date||Dec 3, 1946|
|Priority date||Dec 3, 1946|
|Publication number||US 2501481 A, US 2501481A, US-A-2501481, US2501481 A, US2501481A|
|Inventors||Taggart Dawson M|
|Original Assignee||Western Electric Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (5), Referenced by (2), Classifications (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
March 2l\ 1950 D. M. TAGGART APPARATUS FR TESTING CABLE ELEMENTS Filed Dec. 3, 1946 Patented Mar. 21, 1950 APPARATUS FOR TESTING CABLE ELEMENTS Dawson M. Taggart, Ruxton, Md., assigner to Western Electric Company, Incorporated, New York, N. Y., a corporation of New York Application December 3, 1946, Serial No. 713,641
(Cl. 21S- 11) 3 Claims.
This invention relates to apparatus for testing cable elements, and more particularly to apparatus for testing elements forming parts of coaxial cable units.
Coaxial cables are widely used in long distance telephone transmission lines and usually consist of a plurality of individual coaxial units twisted together to form a composite core which is enclosed in a lead sheath. Each of the coaxial units consists of a solid central conductor, an outer tubular conductor formed therearound and spaced concentric therewith by disc-shaped insulators spacedly positioned on the central conductor and a steel tape spirally wrapped around the outer conductor.
It was found that the transmission characteristics of the coaxial units are vitally affected by the presence of conductive faults within the coaxial unit which provides a path of reduced dielectric strength between the central and outer conductors. These faults may take many forms, the more common being a microscopic conductive lm of dirt on the insulating discs, bits of metal embedded in the discs, or very iine metallic slivers or splinters attached to the' central conductor.
In the manufacture of such coaxial units, a solid conductor is continuously advanced through a coaxial unit forming machine, which first applies the insulator discs thereon in uniform spaced relation to form a coaxial unit core. The central conductor with the discs attached is advanced through a high potential electrode for the purpose of electrically burning away any conductive faults that may be present in the conductor and disc assembly and then through a high potential testing electrode to ascertain whether or not any faults remain. If no faults are detected by the testing electrode the outer tubular conductor is formed over the discs by a subsequent operation of the forming machine. i
The types of electrodes used heretofore for burning out faults in and testing the conditions oi such a conductor and disc assemblage are provided with a substantially circular passage designed to slidably engage the peripheries of the discs positioned on the advancing conductor. It was discovered that the central conductor and disc assembly did not travel in a fixed path between the disc applying apparatus and the outer conductor forming apparatus of the coaxial forming machine, but varied slightly in all directions. This variation in the travel of the conductor caused the discs to engage portions of the circular passage through which they were advanced with such force that sometimes the discs were displaced on the central conductor.
ln addition, the passage through this type of electrode must be elliptical in cross section in order that slightly oversize insulatingl discs may be advanced therethrough without being displaced on the central conductor. Consequently, the average insulating disc contacts the elliptical passage at the top and bottom only, which means that any fault which happens to be located outside oi the direct line between the point of contact between the disc and the electrode and the grounded central conductor may not be removed by the burn-out electrode.
In order to overcome the disadvantages present in the types of electrodes known heretofore, it is desirable that an electrode be provided in which no relative movement occurs between the contacting members and the insulating discs of the core, and the contactiing members engage the entire periphery of the discs.
An object of the invention is to provide new and improved apparatus for testing cable elements, and more particularly to provide simple and effective apparatus for testing elements of coaxial units.
In accordance with a specific embodiment of the invention, there is provided an electrode for impressing a high potential across a continuously advancing coaxial unit core which comprises a pair of endless chains driven. in timed relation with the advancing core unit and arranged to carry a plurality of disc contacting members. The chains are synchronized with each other so that their respective electrodes come together at a predetermined point and completely engage a disc on the advancing core and move in unison with the advancing core so that no relative movement occurs between the contacting members and the discs of the core unit. a
A clear understanding of the invention may be had Jfrom the following detailed description oi a specic embodiment thereof, when read in conjunction with the appended drawing, in which:
Fig. l a diagrammatic side view of a coaxial unit forming machine showing testing electrodes embodying the invention;
Fig. 2 is an enlarged, plan View of one' ofthe electrcdes shown in Fig. l;
Fig. 3 is a vertical, sectional view taken along line 3--3 of Fig. 2, and
Fig. 4 is an enlarged, plan View of a portion of the apparatus shown in Figs. 2 and 3.
Referring now to the drawing and more particularly to Fig. 1, a coaxial unit forming machine, indicated generally by the numeral IS, has a capstan 1I associated therewith which serves to advance a conductor l2 from a suitable supply source (not shown) through a disc applying apparatus `,I3,`of a suitable design, by the aid of which insulating discs ifi-I4 are positioned on the conductor I2 at uniformly space intervals to form a coaxial unit core I5. As the core I5 is continuously advanced from the disc applying apparatus I3, it is engaged by a burn-out electrode It, a testing electrode I1 and then passes through a tube forming die i8 which forms a copper tape 2G vdrawn from a supply pad 2| longitudinally around the discs Iii-I4 of the core I5 for form a tubular conductor 22. The partially formed coaxial unit advances through a taping head 23, of knowndesign, by means of which a plurality oi steel tapes are servedis'pirally around the conductor 22 to form a completed coaxial unit 24, which, after passing, around the capstan II several times, is diu 4rected to suitable takeup means (not shown).
The burn-out electrode I6 is connected to one side of a high potential burn-out circuit ener- "fgized and controlled by suitable electrical apparatus indicated generally at by a conductor The. testing electrode I1 is connected to one side "of a hignpotential testing circuit also energized aridcontrolled by the electrical apparatus indicated generally at`25 by a conductor 21 (Fig. l).
The oppositev side of the burn-out circuit and the testing circuit are connected to ground, and the A"conductor lI2 is connected to ground at 28 which "arrangement serves to apply a high burn-out or Atesting'potential across the portion of the core ISen'g'a'ged bythe electrodes I 6 and i1, respec-1 tively. The purpose of the'burn-out electrode l 5 "is to electrically burn' away or vaporize any corductive fault which might be present in the core I5, andthe purpose of the testing electrode Il is to test the lcore I5" after it has been treated by 'the testingv electrode I5 to ascertain whether any conductive faults remain in the core.
The electrical apparatus indicated generally at 25 is as 4sociated with the testing electrode I1 in such a "manner that, should' any fault be present in the `portion of the core I5 being engaged by the test- `ing electrode I1, the driving means (not shown) for the entire coaxial forming machine lli is den energized thereby preventing the tubular con- 'ductor 22 'from being formed around a defective core.
It is believed to be Iapparent that the capstan `I I, the' disc applyingapparatus I3 and the taping head 23 must be driven in timed relation with ref y,spect toy each other in order to form a uniform `4coaxial unit 24. Therefore, when a defect in the core `I5 is'not eliminated by the testing electrode I6, an electrical circuit is formed therethrough by means ofthe testing electrode I1 which serves to deenergize'all thedriven elements of the coaxial `unit`macliine IU' simultaneously. For a complete description and disclosure of the electrical ciru cuit and apparatus associated with the burn-out respectively, are identical in construction and operation and for that reason only the burn-out '3U (Fig. 2).
vided in the arms '4d-M,
electrode I6 will be described in detail hereinbelow.
Referring now to Fig. 3, it will be noted that the electrode I6 comprises a rectangular base 30 oi' suitable electrical insulating material and having a bore 3l provided adjacent to each corner thereor` for receiving a self-lubricating bushing 32. Each of the bushings'32-'32iis provided with a hanged head which serves to maintain the bushings in proper position in the bore 3l provided in the .base 3U. A shaft 33 is provided with a reduced body portion 34, which is rotatably positioned in the bushing 32 positioned in the bore Si provided in the lower right hand corner of the baseS (Fig. 2), and is provided with a shoulder 35 which slidably engages the head oi the respective `bushing `32. A sprocket 36, made of insulating material, such as Micarta, or the like, is secured on the" upper end of the shalt 33 and engages a roller chain belt 31 which in turn meshes with a sprocket also made of suitable insulating material. The sprocket 4D is secured on the upper end of a shaft' 4I rotatably mounted in the bushing 32 positioned in the bore'il provided in the lower left hand corner of the base The shaft 4I is mounted in its respective bushing 32 substantially in the same manner as is illustrated in Fig. 2 for the shalt '33 and isl provided with a shoulder which serves 'to maintain the sprocket 40 horizontally aligned with' the sprocket 36 so that the chain 31 connecting the two sprockets travels in a horizontal path with respect to the base 30.
Alternate links of the chain 31 have arms fifi-4;! 'formed integrally therewith which serve to form a plurality of vertically aligned spaced supports 'on alternate links throughout the tire length of the chain. A contact mero. is pivotally mounted between each pair oi.' v .cq/- cally aligned armsM-M by means of a pin positioned in vertically aligned bores provided in 'ne arms lill- 44. Each contact member IPF- i';
provided with 'a semicircular groove 41 (Figs. 2
and 3) which loosely engages a pin 5l) positioned inanother pair of vertically aligned bores pro- Pins -50 are designed to engage the semicircular groove 61 of the members 45-'45 and prevent the members from turning haphazardly about the pin 43 and thereby maintain the members in a substantially parallelposition with respect to the particular link on which the member is mounted. At the same time, the pins 5Fl-50 are undersize with re- ,spect to the size of the groove 41 so that slight Vmovement of the member' d5 about its respective pin 46 is permitted in either direction.
Each of the members 45-45 is provided with a longitudinal semicircular groove 5I in its outer face, the diameter of which is substantially the same as the diameter of the average insulating disc I4 positioned on the conductor i2. The members 45-45are'designed so that the somicircular grooves 5I-5I will engage substantially one-half of the peripheries of the discs I4-l4 positioned on the central conductor I 2.
A shaft is provided with a reduced body portion 55 which is rotatably positioned in the bushing 532 positioned in the bore 3I provided in the upper right hand corner of the base 30 (Fig. 2), and is provided with a shoulder 51 which slidably engages the flanged head of the bushing. A sprocket 60, made of suitable electrical. insu- `lating material, is secured on the upper end of the shaft 55 andengages a roller chain belt 5I Which'rneshes with a sprocket 62, likewise made of suitable insulating material. The sprocket 62 is secured on the end of a shaft 63 which has its reduced body portion (not shown) rotatably positioned in the bushing 32 positioned in the bore 3| provided in the upper left hand corner of the base 30 (Fig. 2). a reduced body portion and a shoulder substantially the same as that illustrated for the shaft 33, which shoulder serves to maintain the sprocket 62 in horizontal alignment with the sprocket 68 mounted on the shaft 55. It will be noted from Fig. 3 that the sprockets 66 and 62 which carry the chain 6I are maintained in the same horizontal plane as the sprockets 36 and 4l) which carry the chain 31, whereby the chains 31 and 6| travel in the same horizontal plane.
The chain 6| is identical in construction with the chain 31 and has contact members 64-64 mounted on alternate links in the same manner as that described for the contact members 45--45 mounted on the chain 31. The members 64-64 are identical in construction with the members 45-45, having a longitudinal semicircular groove 65 in the outer face thereof which is designed to engage substantially one-half the periphery of the insulating discs I4-I4, and a'vertical semicircular groove 66 which loosely engages a pin positioned on the chain 6I in the same manner as described for the chain 31. n
The reduced body portion 34 of the shaft 33 extends beyond the bushing 32 and through a bore 61 provided in a partition 69 of the coaxial forming machine II). so as to receive a gear 68 (Fig. 3). The gear 68 meshes with a gear 16 secured on the end of the reduced body portion 56 of the shaft 55 which extends through a bore 1I provided in the partition 69 and aligned with the bore 3| provided in the base 30. The gears 68 and 10 are positioned on the shaft portions 34 and 56 of the shafts 33 and 55, respectively, so that the electrodes 45-45 and 64-64 positioned on the adjacent portions of the chains 31 and 6I will line up juxtaposed with each other in the manner shown in Fig. 2. This gear drive between the shaft 33 and the shaft 55 will main- J tain the chains 31 and 6| and the electrodes 45-45 and 64-64, respectively, positively synchronized with each other when the electrode I 6 is driven in a manner presently to be described. A worm gear 12 is secured on the extreme end of the body portion 34 of the shaft 33 and engages a worm 13 secured on a shaft 14 which is rotatably supported in a suitable manner on the partition 69. A sprocket 15 is secured on the shaft 14 and meshes with a roller chain belt 1 6 which in turn engages a sprocket (not shown) driven in timed relation with the disc applying apparatus I3 and the capstan II of the coaxial forming machine Il). The chain 16 and the sprocket 15 are arranged to drive the shaft 14 in a given direction so that the worm 13 and the worm gear 12 will drive the shaft 33 and its respective sprocket 36 in a clockwise direction as indicated by the arrow positioned thereon (Fig. 2).
This direction of rotation of the sprocket 36 serves to advance the inner leg of the chain 31 and the members 45-45 carried thereby from left to right, which is the same direction of travel as that in which the core I is being advanced from the disc applying apparatus I3 by the capstan II. The speed ratio between the driven sprocket and its driving sprocket (not shown) provided on the coaxial forming machine I0 and the speed ratio between the worm 13 and,
The shaft 63 is provided with' the worm gear 12 is arranged to rotate the shaft 33 and the sprocket 36 at a speed which will advance the inner leg of the chain 31 and the members 45-45 from left to right at the same rate of speed as that travelled by the core I5.
The gear 68 drives the gear 10 (Fig. 3), the shaft 55 and the sprocket 60 secured thereon in a counterclockwise direction which advances the inner leg of the chain 6I and its associated contact members 64-64 from left to right in unison with the members 45--45 and the advancing core I5. A sprocket 11 is provided on the extreme end of the body portion 56 of the shaft 55 and meshes with a chain 18, which in turn is connected to a similar sprocket (not shown) mounted on the testing electrode I1 and arranged to drive the testing electrode |1 in the same manner as that described hereinabove for the testing electrode I6.
In order to maintain the grooves 5| and 65 of the contact members 45-45 and Bil-64, respectively, tightly against the periphery of the discs I4-I4 positioned on the advancing conductor I2, there is provided a pair of vertically aligned guides 86 and 8| (Figs. 2 and 3). The guide (shown in detail in Fig. 4) is secured to the base 38 by screws 82-82 and is provided with a longitudinal groove 83 forming side walls 84-84 whose ends 85--85 curve outwardly and join the sides of the guide 86. The bottom surface 86 of the groove 83 has its end portions 81-81 adjacent to the curved walls 85-85 tapered downwardly toward the base of the guide 80. The guide 88 is positioned on the base 3D so that the longitudinal axis of the groove 83 is aligned with the central axis of the electrode I6. The width of the groove 83 is such that the inner surface of the walls 84-84 thereof slidably engage an elongated shoulder 88 and an elongated shoulder` 90 provided on the lower portion of the contact members 45-45 and 64-64, respectively, While the depth of the groove 83 is such that the bottom surface 86 thereof is slidably engaged by the bottom face of the contact members.
The guide 8| is identical in size and shape with the guide 80 but it is secured in an inverted menner above the chains 31 and 6I on a U-shaped support 9| (Figs. 2 and 4) which is mounted on the flanged portions of the guide 80. The guide 8| also is provided with a longitudinal groove 92 having side walls 93-93 whose end portions 94--94 curve outwardly to join the sides of the guide 8|. The bottom surface 95 of the groove 92 has is end portions, one of which is indicated by the numeral 96, adjacent to the curved walls 94-94 tapered upwardly toward the top of the guide 8|. The guide 8| is positioned on the support 9| so that its longitudinal groove 92 is vertically aligned with the groove 83 of the guide 80. The width of the groove 92 is equal vto the width of the groove 83, consequently, the
inner surface of the side walls 93-93 thereof slidably engage elongated shoulders 91 and 98 provided on the -upper portion of the contact members 45 and 64, respectively.
The depth of the groove 92 is substantially greater than the depth of the groove 83 in order that a pair of elongated leaf springs IDU- |06 may be secured to the bottom surface 95 (Fig. 3)
downwardly from the bottom of the groove in the path of the'contactmembers advanci'ngthroirgh and since they have only onej end secured"t'o'the surface 95`the opposite end of'each springisfree to slide on the bottomsurface as ythe 'spring is urged upwardly by engagement with 1the upper face of the contact members 45 and 64,
When the chains 31 and 6I are being driven in a` manner described hereinabove, each synchronized pair of contact`members45 `and "64 enter the grooves 83 and 92 of the guides 8|) and 8|, respectively, whereupon 'portions `of #their respective shoulders '88, 4SI1, 90 and `598*"slidably engage the inner vside of4 the adjacent curved Walls 85-85 and 93-93 of the grooves. As each pair 'of members 45 and |54 advance further into the grooves, the entire length of their respective shoulders slidably engage the"adjacent sideA walls of the grooves 83 andilrespectively, in" which position the walls'serve' to hold the semic'ii'fcular grooves and E5 of the members k45'and`64, respectively, tightly against the periphery "of a disc I4 engaged thereby. IDD-I resiliently urge the'contact members and 64 engaged thereby downwardly in the lgroove 83 of the guide 80 so that the bottoms of the contact members make a good physical 'contact with the bottom surface 86 thereof as the contact members are advanced through' the guides 80 and 8|. The ends 85-85 and 96--96`of'the grooves 83 and 92, respectively, are taperedas described so as to prevent the ends of the contact members 45 and 64 from striking the end of f the guide and thereby damaging the Contact members or the chains carrying the 'contact members.
Since the discs I4|l 'are'positioned on the conductor I2 at uniformly spaced intervals by the disc applying apparatus I3, the chains 31 and 6I are selected to have a pitch Aequaltoene-half the distance between. the-discs I4-I4posit'ioned on the conductor i2.y By'posltioning the 'contact members =i5455 and 64,-64 on alternate links of the chains 31 and 6I, respectively, having such a pitch it is possible to obtain such a spacingof the members that each pair of contactmeinbers consisting or one member 45 and one memberf 64 will engage single disc of the advancing core I5. Since the pitch of the chains 'Sland' 6I is equal to one-half the spacing of the discs on the conductor and since the chains are'driven in` timed relation with the advancing conductor, no rela--k tive movement occurs between the disc and 'the cont-act members as successive pairs of contact members come together andV engage the discs on the conductor. The contact members are centrally mounted on their respective chain'belts and are or .such length that the ends thereof butt against the ends of adjacent members When a pair of Contact members 'come together in the grooves'33 andQZ yof the guides `80 andl, respectively, the semicircular grooves 5| and65 provided in the contact members form a complete circular channel with the exception of a very slight clearance provided between oppositely disposed contact members.
rherefore, when'two members'come together on the disc I4 of the core I5, practically' theentire periphery ofthe disc is engaged thereby. The normal amount of play which existsbetween the contact members and theirrespectivesupporting links, and between' the iridividuallinks ofthe' 'chains makes the contact members some- The leaf springs what selfadjustable,"tliereby enabling `the testing electrode I6 toengagea substantial portion of thcperipheryof each disc 'of'the'coaxial unit core I5, irrespectivelof the fact that the diameter of the discs may vary slightly. 4Obviously, the chains 31 and *6| `couldbe selected "to have a pitch equal to vthe 'spacing of the discs on the conductor or `any sub-multiple of the spacing and stillbe operated so that no relative movement occurs betweenthe contactl'm'embers and the discs engaged'thereby.
VThe bared endofl the conductor 26 is secured -Ito-the `support r9| byA a screw IDI and thereby serves toconne'ctthe g`uides180`and 8| directly to one side-of 'the high potential'burn-out circuit energizedand controlled 'by "theelectrical apparatus indicatedg'enerallyat 25. `Byvirtue of the fact that each pairof juxtaposed contact memybers and 64 slidably engagethe guides 8U and A8| as they are' advanced by their-respectivc'chains 31 and 6| from left to right with the 'advancing core I5, they are 'in"`turn "charged with the high burn-out-potentiaLin vwhich case the entire portion of the 'core I5` engaged by each pair of juxtaposed contactm'embers is thereby subjected tothe burn-out potential. The high -potential burn-out circuit "is connected directly to the guidesVA 80 and I so 'that if a 'breakdown should occur at a fault present in that portion of the core I5 engagedv by the" several pairs Aof 'contact members positioned inthe `groove 82 of .the guide "118B, 'the high current owing infthe circuit as a result of the breakdown is conned tothe 'guide '8G andthe particularpairof electrodes enclos- 'ingthe fault andtherefore is not permitted to travelV through any portion of' the chains 31 and fSI. The four sprockets-*36,A 40, 60 and 62 are `made'of 'suitable insulating material in `order-to completely insulate Ithe contact i members rand their respective chains from the" coaxial forming machine because thevforming=machine andthe Jcentralconduc'tor `I2 `are' grounded Tat A28, as is the l opposite side 1 of i the high potential circuits vconnectedto the electrodesl andfI'I.
machine'of Aknown 'design7 such as the coaxial forming machine indicated generally at I0, so astc engage the discs I4I4of`the core I5 immediately after the-insulating discs have been `placed on the central conductor I2 by the disc applying apparatus r I 3. are being driven at the proper rate of speed so The chains 31 and 6I asto advance their respectivecontact members Afrom leftto'rightat thesame rate of speed as that at which thecore I5 is being'aclvanced by the capstan "II. The chainsare synchronized with the movement of the core I5 and' with each other sothat'each oppositely disposed pair of vcontact members'consisting -of"a"contact member 45 and a Contact member 64"ccme completely togetherfandsurround aportion of the advancing core I5"including a portion of the conductor I2 and an individual disc I4 positioned thereon as the disc reaches the transverse center line of the sprockets 4an'd'62. Thereafter, the members45 and 64, whichhave been' brought together andinowenclose a portion of thecore I5, travel withl the conductor and the disc from left to right until thed'isc and the contact members reach the `transverse centerlinec'f` the sprockets l36 and.
Duringthisportion of travel of the conductor and disc,"v the contact members slldably engage `the-wal1sH8484`andbottom 86 of' the groove 82 provided in the guide 80 and the walls 93-93 and leaf springs IUD- of the guide 8|. Since the guide 80 is connected by the conductor 26 to one side of a highpotential burn-out circuit energized and controlled by the electrical apparatus indicated generally at 25, the conductor I2 and the discv I4, being surrounded by the contact members, has the high potential applied around their respective peripheries, there being an air dielectric surrounding the central conductor I2 (Figs. 2 and'3). The springs I IBD-IUE engage the upper surface of the contact members and resiliently urge the bottom surfaces against the bottom 86 of the groove 83 thereby providing a good electrical contact between the contact members and the guide and preventing any arcing which may occur from a loose contact between the guide and the members.
Should there be afault in the engaged portion of the core I5, such as conductive foreign matter embedded in the disc or metallic slivers attached to the surface of the conductor I2, a path of reduced dielectric strength occurs between the members 45 and 64 and the grounded central conductor I2. Since the opposite side of the burn-out circuit is grounded, the burn-out potential breaks down the fault and a high current flows therethrough causing the fault to be burned out or vaporized.
It should be noted that the high current caused to flow in the high potential circuit due to a breakdown of the fault in the core I is not allowed to flow through the links of the chain or through the pins which pivotally support the contact members 45-45 and 54-64 on their respective chains. The current-'flowing through the fault is confined between the members 45 and 64 and the guide 80, thereby preventing any arcing or pitting to occur between the various moving elements ofthe electrode I6.
As the core I5 and the discs are advanced further toward the right, the members separate and leave the disc and are carried-around by their respective chains until they are again in position to engage another portion of the advancing core. It is obvious that no relative movement occurs between the contact members and the discs engaged thereby, in which case the discs cannot in any way be displaced on the cene tral conductor by engagement with the burn-out electrode I6.
Since the discs I4-I 4 positioned on the central conductor I2 are not advanced through the circular passage formed by the grooves 5I and 65 provided on the contact members 45-45 and SII- 64, respectively, the shape of the grooves can be made to conform exactly to the peripheries of the discs and thereby engage substantially the entire periphery thereof except for the Very small clearance provided between a pair of oppositely disposed members. Because of this fact, a good mechanical contact between the contact members 45-45 and 64-64 and the peripheries of the discs is obtained, thereby eliminating the possibility of an air gap being present between contacting surfaces of the grooves 5I and 65 of the contact members and portions of the peripheries of the discs, which air gap may prevent the contact members from burning out a fault present in the advancing core I5. It should also be noted that the members 45-45 and 64-64 are so designed that when several oppositely disposed pairs are aligned against the walls 84-84 of the guide 80 and the walls 93-93 of the guide 8l, the individual contact members of each chain butt against each other. This ar-l I before the core I5 is engaged by the testing electrode I'I.
After being engaged by the burn-out electrode I6 the advancing core I5 is engaged by the testing electrode I'I before being advanced through the tube forming die I8. The mechanical construction and operation of the testing electrode I'I is identical with that of the burn-out electrode I6 described hereinabove. However, in its electrical operation the testing electrode I1 varies from that of the burn-out electrode, in that the electrode I'I serves to arrest the operation of the coaxial forming machine when a fault is present in the core I5. The electrode II is connected to one side of a high potential testing circuit energized and controlled by the electrical apparatus 25, and thereby applies a high potential around the peripheries of the insulating discs and the grounded central conductor. If any faults remain in the core I5 after being engaged by the electrode I6, the high testing potential breaks down the fault and a high current flows in the circuit. This breakdown current operates current responsive apparatus included in the elec trical apparatus 25 to arrest the driving means of the forming machine thereby preventing the defective core I5 from having the tubular conductor 22 formed thereover by the tube forming die While the above-described electrodes are particularly well adapted to test coaxial unit cores and prevent the machine from forming a defective coaxial unit, they may be modified to test various types of conductors without departing from the invention, as defined in the annexed claims.
What is claimed is:
1. In an apparatus for electrically testing a continuously advancing coaxial unit core consisting of a filamentary central conductor having insulating discs spacedly positioned thereon including means for grounding the central conductor and a source of high voltagel an improved electrode for applying a high potential around the advancing core, which comprises a chain belt having a pair of spaced supports provided on alternate links thereof, said chain belt being positioned to one side of the advancing core and having the axis of its path of travel in the same plane with the longitudinal axis of the advancing core, a contact member pivotally mounted between each pair of spaced supports and having a semicircular groove along the face thereof, a second chain belt having a pair of spaced supports provided on alternate links thereof, said second chain being positioned on the opposite side of the advancing core and having the axis of its path of travel in the same plane with that of the first-mentioned chain belt, a contact member pivotally mounted between each pair of spaced supports of said second chain belt and having a semicircular groove along the face thereof, means for driving said first and second chain belts in unison so as to advance the contact members on the adjacent legs thereof in the same direction and at the same rate of speed as that travelled by the advancing core for a predetermined portion of their travel, said chain belts being synchronized so that the contact members on the adjacent legs of the chain belts are juxtaposed during their period of travel with the core unit and so spaced. that the contactvl members on the. adjacent legs thereof enclose a.
portion of the. core advancingv therebetween, and upper and lower guides for holding each pair of advancing juXtaposedcontact members together during their travel with the core so that their. respective semicircular groovesA engage the periphery of the discs of the core. unit.
2. In an apparatus for electrically testing a -continuously advancing coaX-ial unit. core consisting of alamentary central. conductor having insulating discs spacedlyv positionedgthereon including means for` grounding the. centralconductors and a source of high-voltage, an improved electrode for applying a high Potential aroundlthe advancing core,. which comprises a chain. belt having a pair of spaced. supportsV provided on. alternate links thereof., said. chainbeltbeing positioned to one side of the advancing core andthe axis of its pathA of. travel in the same plane with` the longitudinal axis of the.core,.a-contact mem.-v ber pivotally mounted between each pair of spaced supports and havingasemicircular groove.
along4 the face thereof, a. secondchain. belthaving a pair of'spaced. supports provided` on.. alternate links thereof, said second chain. being` positioned on the opposite sideof the.. advancing core and having the axis of its. pathof travel. in the same plane with thatof the rst-rnentionedlchain belt, an elongated contact.v member pivotally mounted between each. pair of spaced supports ot said second chain belt and havingasemicircular groove along the face thereof adjacent to the coreA unit, means for driving said rst and second chain belts so as to advance. their respective contact members in the same directionas and at the same.
linear speed as that travelled by the advancing core for a predetermined portion of vtheir traveL,
means for synchronizing the movement of the chain belts so that the contact members of. each4 ing: of` a nlamentar-yrcentrmconductor having insulating, discs' spa'cedlyr positioned thereon includinga. high voltage. testingl circuit and means i'or connecting the, central conductor to one side thereof, `an improvedeleotrode for applying a high potential. aroundtheadvancing core, which comprises a-pair of endless chain belts spaced equidistantly astride the path` of travel of the advancing core and having the axis of their respective paths of traveleligned with the longitudinal axisofthecore, a.` plurality of." contact members mounted on. each chainbelt and having a semicircular groovetherein for engagingI the peripheries of the discspositioned on: said advancing core, means' for. driving, the. chain belts so that the adjacent legs/travel inthe same direction and at-thesamelinearv speed as that oiY the advancing core, means for synchronizing` the-movement of said chain.belts.witht respect toseach other so that thefcontactmembers on the adjacent legs of the chain belts are juxtaposed; during, their period of travel with the advancing, core, saidI chain belts being sospaced with respect to the core advancing. between. said. adjacent legs, upper and lower guides arranged to hold the contact: members against the discs onq the advancing conductor for. a predetermined length of travel. of the contact-members, resilient-means provided on the upper guide member for urging thecontact members downwardly so thatthey makea. good sliding contact with the lowerv guide therewith, and means for electrically insulating` the chain belt synchronizing means. and .driving means from the track members, wherebywhen one side of asource of potential is connected tothe lower track member the contact members engaged thereby are raisedr teva. valueoi potential substantially above that of the central conductor of the advancing core.
DAWSON4 M. TAGGART.
REFERENCES. CITED The following references are of record i'n the file of this patent:
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|U.S. Classification||219/155, 324/516|