MXPA00003942A - Method of and apparatus for making twisted cable and the cable produced thereby - Google Patents

Abstract

A method of and an apparatus for making twisted electrical cable (T), such as 600 volt secondary distribution (UD) cable, and the twisted cable product are disclosed. The apparatus comprises a first plurality of stationary payoff reels (32) each wound with a length of stranded bare wire conductor (C). The stranded conductors (C) are simultaneously payed off the reels (32) to a pay out accumulator (34) for accumulating a portion of the stranded conductors during replacement ofspent pay out reels (32). An extruder apparatus (36) arranged downstream of the accumulator (34) applies a plastic insulation material to a respective stranded conductor (C) as it passes through the extruder (36). A cooling trough (42) through which water is flowed cools the plastic insulation. A take-up accumulator (20) arranged downstream of the cooling trough (42) accumulates a portion of each insulated conductor during changeover of the take-up (28) arranged downstream of the take-up accumulator (20). The take-up (28) is rotated about a first axis to twist each insulated conductor about its longitudinal axis and to simultaneously twist the insulated conductors about one another to form a twisted electrical cable. The take-up (28) is also rotated about a second axis for taking up the twisted electrical cable. The twisted electrical cable product (T) made according to the method of the invention comprises a plurality of insulated conductors (50) each twisted about its longitudinal axis by the apparatus of the invention and twisted about one another.

Description

METHOD OF AND APPARATUS TO MANUFACTURE TWISTED CABLE AND CABLE PRODUCED BY THESE Field of the Invention The present invention relates to wiring methods and apparatuses, and more particularly, to a method of and an apparatus for manufacturing twisted cable products such as, for example, underground distribution cable (UD) of secondary, 600 volts, in a continuous online process.

BACKGROUND OF THE INVENTION There are several well known methods of, and apparatuses for making products of twisted electrical cable. For example, U.S. Patent Nos. 3,686,843; 4,133,167; 4,171,609; 4,215,529; 4,426,837; 5,239,813; and 5,557,914 describe a few of the many different types of torsion and wiring methods and apparatus that are used to twist conductors or wires and to make twisted electrical cables. In another conventional method, a plurality of aluminum or copper wires are braided together into a single bare braided conductor, which is then insulated with a polymeric insulation, preferably by extrusion. The insulated braided conductor is wound on a reel, tested on its reel, which is then stored for later use. Two or more of the insulated stranded conductor reels are taken from the warehouse and mounted on a wiring device for distribution simultaneously. As the conductors are distributed from the reels, they are twisted together to form a twisted cable and the twisted cable is wound on a reel. Typically, each insulated conductor is redistributed from its spool in an un-twisted condition, and the conductors are then twisted together in a planetary assembly, ie, without each individual conductor being twisted about its own longitudinal axis. The conventional method mentioned above has hitherto been used to manufacture secondary power distribution cable, such as, for example, 600 volt triple ÜD cable, and represents the state of the art for the manufacture of such a cable. One disadvantage of the conventional method is the large number of manufacturing steps "involved in the manufacture of the cable, the number of manufacturing steps is increased in part due to the requirement to provide management control and inventories in the process of the large reels of bare, uninsulated conductors, which typically comprise 7, 19, or 37 copper wires or aluminum, as well as the control of handling and inventory in the process of the same large reels after the insulation material has been extruded on the naked conductors not isolated and cured, to form the insulated conductors that are subsequently wired together in the cable of twisted electrical distribution. Substantial storage space is also required in the process, both for large reels of bare stranded conductors, and for equally large reels of insulated stranded conductors. In addition, each extrusion line to apply the plastic insulation to the conductors requires a substantial plant floor space for the equipment needed to unwind the bare stranded conductor, extrude the insulation over the stranded conductor, and take the stranded conductor isolated over a reel Especially a substantial floor space r is required for the total cooling necessary to cure the insulation material, before the braided conductor is insulated or wound on a reel. It would be desirable, therefore, to provide a method and apparatus that reduces the steps of handling in the process, the storage requirements in the process and the floor space of the plant needed to the conventional method and apparatus for making twisted electrical cable, such as 600 volt UD cable.

Brief Description of the Invention In view of the above limitations and disadvantages of prior art methods and apparatuses, as well as other disadvantages not specifically mentioned above, there is still a need in the art to improve the processing of, and the apparatus for making twisted electrical cable. The present invention is directed to an improved method and apparatus for making twisted cable and the cable manufactured by them. The method and apparatus of the invention outweigh the majority, if not all, of the disadvantages of the methods and apparatuses of the prior art, as described more fully hereinafter. According to the broader aspects of the method and apparatus of the present invention, a plurality of reels containing bare braided conductors, for example, 19-wire braided aluminum conductors, are assembled to be distributed simultaneously from bare braided conductors of a plurality of stationary distribution stations. Means are provided for the simultaneous change or replacement of the Depleted reels with a new set of reels filled with stranded conductors, including a soldering station in each distribution station to weld the front ends of the stranded conductor distributed to the front ends of a stranded conductor to be distributed. The bare stranded conductors are fed from the distribution stations to a plurality of distribution accumulators, one for each distribution station, where the conductors ~ accumulate during the simultaneous change of the stationary distribution spools and weld the ends of the stranded conductor between the reels. Each of the plurality of bare stranded conductors is fed from respective distribution accumulators, separately, to an extrusion station where an insulating plastic material, such as the XLPE silane, is extruded onto each braided conductor. For example, in the case of the manufacture of a 600 volt triple UD cable, the extrusion station can include three separate extruders, each feeding an extrusion head and a respective extrusion die or a single extruder with multiple (three) separate extrusion matrices. Preferably, a tape extruder is provided conventional in the extrusion station to extrude the surface liner, for example, three tapes 120 ° apart, on one of the three extruded plastic insulations to identify the neutral conductor. The location of the welds in each braided conductor was marked downstream of the extruders for a purpose to be described. After the plastic insulation is extruded onto each braided conductor, the plastic insulation is cooled by passing the insulated conductors simultaneously through a common water cooling passage current below the extrusion station. The individual insulated conductors are fed downstream to a respective tap-in accumulator used to accumulate the insulated stranded conductors during the change of the twisted cable-take-up reel. From the intake accumulators, the insulated twisted conductors are guided through a closing die and consequently to a rotating take-up pulley and a take-up reel or a rotary reel take-up apparatus. The rotary reel take-up apparatus or rotation of the take-up sheave twists each individual insulated conductor about its longitudinal axis and the plurality (three) of insulated conductors are twisted, inter alia between the take-up reel, simultaneously take the twisted cable. When the welds marked on the individual stranded braided conductors of the twisted cable approach the take-up spool, the winding stops and the insulated stranded conductors accumulate on the take-up accumulators. Next, the welds of the twisted cable are cut and at the same time the full take-up reel is removed and replaced with an empty take-up reel. Because the finished twisted wire can not have any solder in the conductors, the welds are cut off from the conductors of the finished twisted wire. Accordingly, the welds between the rear ends of the conductors on the spent distribution spools and the leading ends of the conductors on the replacement distribution spools must pass through the wiring apparatus substantially at the same time, i.e. same longitudinal positions in relation to the others. If the welds in each insulated conductor are separated longitudinally from each other by a substantial distance during the manufacture of the twisted wire, a long section of twisted wire must be cut and discarded to ensure that the weld does not remain on the finished twisted wire. For that reason, welding operations to connect the conductors distributed from the stationary distribution reels are preferably effected simultaneously on all conductors in the same upstream location to avoid unnecessary waste of finished twisted cable. With the advantages and previous characteristics of the invention that will become evident here later, the nature of the invention can be understood more clearly by reference to the following detailed description of the invention, the appended claims and the various views illustrated in the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGURE 1 is a schematic plan view of the apparatus of the present invention; and FIGURE 2 is a cross-sectional view of one embodiment of a twisted cable made according to the method of the present invention, using the apparatus shown schematically in FIGURE 1 and taken along line 2-2 of FIGURE 1. 1.

Detailed Description of the Invention Referring now to the drawings, there is illustrated in FIGURE 1 a wiring apparatus in accordance to the present invention, which is designated generally by the reference numeral 10. Generally, the apparatus 10 comprises, from top to bottom, a distribution station 12, a distribution accumulator station 14, an extrusion station 16, a cooling station 18, a take-up accumulator station 20, a closing die 22, and a take-up station 24, which includes a rotating traction sheave 26 and a rotary take-up station 28. In the scheme of FIGURE 1, the distribution station 12 comprises a plurality of stationary reel dispensing apparatuses 30, each supporting a dispensing reel 32 on which a bare conductor is wrapped, for example, an aluminum wire conductor 19 threads. As used herein, the term "stationary distribution reel" means that the distribution axis X of each reel is fixed and does not rotate about an axis perpendicular to the distribution axis X. The bare braided conductors C are distributed simultaneously from the reels 32 to the distribution accumulator station 14, which in the scheme of FIGURE 1, includes a distribution accumulator 34 for each conductor C. Of the distribution accumulators 34, the conductors The bare braids C are moved together towards the extrusion station 16, where the individual extruders 36 supply an insulating material of molten plastic to separate extrusion dies. The plastic insulation material is extruded onto the bare braided conductors that pass through the extrusion dies. The plastic insulating material v can be any suitable insulating material, such as the XLPE silane. In the scheme of FIGURE 1, each of the extruders 36 supplies molten insulating material to one of the extrusion dies (not shown) located in one or multiple heads 38. As will be understood by those skilled in the art, it is also possible that extrusion dies in a single head 38 can be supplied with molten plastic by a single large extruder or that the extrusion station 16 comprises three different heads, one for each duct and each being supplied with insulating material by a separate extruder. The three heads 38 could be displaced transversely and longitudinally from one another or transversely displaced from, but aligned longitudinally with one another. A separate tape extruder 40 can also be provided in the extrusion station 16, with the purpose of extruding one or more tapes or strips of plastic on the surface of the insulation of the conductor that is going to be the neutral conductor of the finished twisted cable. Conventionally, three strips or strips 120 ° apart of a plastic material having a different color than the insulating plastic on the surface of the insulated neutral conductor are identified to be extruded. When the insulated conductors I leave the extrusion station 16, they enter the cooling station 18 which comprises a passage 42 through which water flows at a temperature in the range of about 10 ° C to about 90 ° C, which The insulation extruded on the conductors I. The temperature of the cooling water may decrease from the inlet to the outlet of the cooling passage. From the water passage 42, the isolated conductors I pass to the accumulation station of intake 20, where they accumulate during the change of the take-up spool. The insulated conductors I are then guided to the closure die 22 from the intake accumulator 20 and then to the traction sheave 26 and wound up 28, both of which can be rotated in a synchronized manner to twist the three insulated conductors together and simultaneously twisting each insulated conductor around its own axis longitudinal. The socket 28 supports a take-up reel 44, which takes the finished twisted cable T. It will be appreciated by those skilled in the art that the torsion of the insulated conductors I one around the other extend upstream of the rotating pulley 26 and the takes 28 towards the closing die and the torque imparted to the conductors around their respective longitudinal axes extends upstream along the closing die 22 to the take-up accumulator 20. FIGURE 2 illustrates in a cross-section taken in line 2-2 of FIGURE 1, the finished twisted wire T which, in the example of FIGURE 2, has two twisted conductors of nineteen (19) wires 50, 52 of a given first diameter and a third twisted conductor of nineteen (19) wires 54 of a smaller diameter than the diameter of the conductors 50 and 52. The smaller diameter of the conductors 54 is the result of using wires of smaller diameter for the neutral conductor 54. The conduit The neutral conductor 54 has on the surface thereof three extruded straps or straps 56 applied by the tape extruder 40. In contrast to the conventional twisted wire in which the individual stranded conductors are twisted around each other in a planetary assembly, the individual conductors 50, 52 and 54 of the cable T shown in FIGURE 2 are non-planetary twisted around their own axes 50 ', 52' and 54 ', as well as twisted together around the T' axis of the T-cable. The external appearance of the cable T made according to the method of the present invention, differs only from that of the cable made according to the conventional method in which the straps or straps 56 on the neutral conductor 54 can be helically oriented on the conductor 54 to the torsion of the driver around his own axis 54 '. To compensate for any tendency of the finished twisted cable T to form twists or patches after distribution due to twisting in the individual conductors around their own axes, each insulated conductor is preferably subjected to a pre-twist before taking it. Although certain preferred modalities up to now of the present invention have been specifically described, it will be appreciated by those skilled in the art that the invention claims that variations and modifications of the different modalities shown and described herein can be made without departing from the spirit and scope. of the invention. Accordingly, it is intended that the invention be limited only to the degree required by the appended claims and the applicable legal rules. It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Claims (18)

1. CLAIMS Having described the invention as above, the content of the following claims is claimed as property. An apparatus for forming a twisted electrical cable, characterized in that it comprises: a first plurality of stationary distribution reels, each wound with a bare cable conductor length having upstream and downstream ends; means for simultaneously distributing bare wire conductors from the reels; first accumulator means arranged downstream of the distribution reels to accumulate a portion of bare wire conductor of each distribution spool; extruder means arranged downstream of the first accumulator means for the application of an insulating material to each stranded bare wire conductor, when passing through the extruder means; means arranged downstream of the extruder means for cooling the insulating material applied to each of the conductors of bare braided wire and forming a plurality of insulated conductors, each insulated conductor has a longitudinal axis; second accumulator means arranged downstream of the cooling means to accumulate a portion of each insulated conductor; take-up means arranged downstream of the second accumulator means and means for rotating the take-up means around a first axis to twist each insulated conductor about its longitudinal axis and simultaneously twist the insulated conductors one around the other to form the electric cable distorted; and means for rotating the picking means about a second axis to take the twisted electrical cable on the picking means. The apparatus according to claim 1, characterized in that the electric cable is twisted. It is a 600 volt electrical distribution cable. The apparatus according to claim 1, characterized in that the extruder means comprises a plurality of extruders each of which has at least one extrusion die, the extrusion dies of such extruders are arranged in a spaced-apart relationship from a position of the upstream die, to a position of the downstream die and are offset laterally to one another in a direction transverse to the distribution direction of the bare wire conductors braided from the distribution spools. The apparatus according to claim 4, characterized in that the extruder means comprises a plurality of extruders, each extruder has an extrusion die, the extruders are positioned so that the extruder dies of the extruders are aligned transversely and are deviated laterally from one another in a direction transverse to the direction of distribution of the stranded twisted wire conductors of the distribution spools. The apparatus according to claim 1, characterized in that the cooling means comprise a passage for cooling the extruded insulation material. The apparatus according to claim 1, characterized in that it includes a localized closure matrix running downstream of the second accumulator means and upstream of the take-up reel for putting the insulated conductors together by twisting. 7. The apparatus according to claim 1, characterized in that the braided bare wire conductors comprise one of 7, 19 or 37 bare aluminum wires, braided together. The apparatus according to claim 1, characterized in that the braided bare wire conductors comprise one of 7, 19 or 37 bare copper wires, braided together. 9. The apparatus according to claim 1, characterized in that it includes three distribution reels, to distribute three stranded stranded wires., which comprise one of 7, 19 or 37 bare aluminum wires, braided together. The apparatus according to claim 10, characterized in that the extrusion means include three extruders, each of which has an extrusion die, the extruders are arranged so that the extruder dies of the extruders are spaced apart from each other. if along the direction of travel of the bare wire conductors and are offset laterally to each other in a direction transverse to the direction of travel of the bare wire conductors. 11. A method for forming a twisted electrical cable, characterized in that it comprises the steps of: simultaneously distributing a first plurality of bare wire conductors, each having ends upstream and downstream of the stationary distribution spools; accumulate a portion of the distributed bare wire conductor of each distribution spool; simultaneously extrude an insulating material on each conductor of bare wire; cooling the insulating material applied to the bare wire conductors to form a plurality of insulated conductors, each insulated conductor having a longitudinal axis; accumulate a portion of each isolated conductor; twisting each insulated conductor around its longitudinal axis and simultaneously twisting the insulated conductors around each other to form the twisted electrical cable; and take the twisted electrical cable on a take-up reel. The method according to claim 11, characterized in that it includes the steps of providing a second plurality of bare wire conductors, each of which has ends upstream and downstream and solder the downstream end of each bare wire conductor of the second plurality of bare wire conductors to a respective upstream end of a bare wire conductor of the first plurality of bare wire conductors. The method according to claim 11, characterized in that the step of curing the insulating material applied to bare wire conductors includes the step of passing the insulated conductors through a water passage after extruding the insulating material onto the insulating material. each stranded stranded wire conductor. The method according to claim 11, characterized in that the step of cooling includes, furthermore, flowing water through the passageway 15. The method according to claim 14, characterized in that the temperature of the water flowing through of the cooling passage, decreases from the entrance to the exit. 16. The method according to claim 14, characterized in that the temperature of the hot water is in the range of about 70 ° C to about 100 ° C. 17. A twisted electrical cable made according to the method, characterized in that it comprises the steps of: distributing a first plurality of twisted bare wire conductors, each of which has upstream and downstream ends from stationary distribution spools; accumulate a portion of the bare braided wire conductor distributed from each distribution spool; Extrude an insulating material over each stranded bare wire conductor; cooling the insulating material applied to the braided bare wire conductors to form a plurality of insulated conductors, each insulated conductor having a longitudinal axis; accumulate a portion of each isolated conductor; twisting each insulated conductor around its longitudinal axis and twisting the insulated conductors around each other to form a twisted electrical cable; and take the twisted electrical cable on a take-up reel. 18. A twisted electrical cable, characterized in that it comprises a plurality of braided insulated conductors, each of which has a longitudinal axis, each conductor being twisted about its longitudinal axis and about one another. SUMMARY OF THE INVENTION A method and apparatus for manufacturing twisted electrical cable (T), such as a secondary 600 volt (UD) distribution cable, and the product of the twisted cable are described. The apparatus comprises a first plurality of stationary distribution reels (32), each wound with a length of bare wire conductor (C). The stranded conductors (C) are simultaneously distributed from the reels (32) to a distribution accumulator (34) to accumulate a portion of the conductors during the replacement of depleted distribution reels (32). At least one extrusion apparatus (36) arranged downstream of the accumulator (34) applies a plastic insulating material to a respective conductor (C), when it passes through extruder (36). A cooling passage (42) through which water flows, cools the plastic insulation. A take-up accumulator (20) arranged downstream of the cooling passage (42) accumulates a portion of each insulated conductor during the change of the take-up spool (28) arranged downstream of the take-up accumulator (20). The take-up spool (28) can be rotated about a first axis to twist each insulated conductor about its longitudinal axis, and can twist simultaneously the insulated conductors, one around the other to form a twisted electrical cable. The take-up reel (28) can also be rotated about a second axis to take the twisted electrical cable. The twisted electrical cable product (T) made in accordance with the method of the invention comprises a plurality of insulated conductors (50), each twisted about its longitudinal axis, by the apparatus of the invention, and twisted one around the other.