US3503120A - Method of producing covered wire - Google Patents

Description

March 31, 1970 P. RQlER-c 3,503,120

METHOD OF PRODUCING COVERED wlim' Filed NOV. 2, 1966 PAUL R PIERCE a, 5

ATTORNEY INVENTOR.

United States Patent US. Cl. 29527.2 11 Claims ABSTRACT OF THE DISCLOSURE An improved method of producing a covered wire and more particularly an electrical insulated conductor from wire annealed in an uncontrolled atmosphere wherein the wire is controllably lubricated by use of a die device prior to the application of a covering to the wire.

This invention relates to a method for producing covered wire. More particularly, it is concerned with providing an improved method for producing covered wire such as insulated electrical conductor wire from an uncontrolled atmosphere annealed, e.g. an open air annealed, aluminum or aluminum alloy wire, wherein the wire, including the objectionable dry oxide surface coating thereof, is controllably lubricated in a wire treating zone prior to introduction of the wire into an extrusion zone where an appropriate covering is applied to the wire.

In the past production of insulated conductors from drawn wire, it has been customary practice to fully or partially anneal the previously drawn wire in one or more heat treatment steps so as to improve the elongation properties and bendability of the wire for final use. In the case of uncontrolled atmosphere annealing, be it a continuous, semi-continuous or batch type annealing process, it has been found particularly in the case of aluminum and aluminum alloy conductor grade wire that an objectionable and pronounced oxide coating is ordinarily formed on the outside of the wire. This coating is very hard in addition to being strongly adherent to the underlying aluminum or aluminum alloy conductor wire. In some instances, during this same type of annealing, the oil lubricant previously applied to the wire during drawing becomes vaporized whereby the outer surface of the wire becomes quite dry. This vaporized oil lubricant, which is usually an appropriate mineral base oil, also tends to form a varnish film on the wire. Unless compensated for, the overall resultant and excessively dry oxide surface coating alone or in combination with the varnish film produces serious galling in the extruding dies which are later used to apply an insulating coating or jacket to the wire as well as excessive die wear. The term galling as used herein means that particles of the oxide coating and varnish film, where the latter is present, are removed from the wire by the insulating extrusion dies and deposited on such dies until the orifices thereof become so diminished or restricted that the wire cannot successfully pass through these dies. In such instances, the wire becomes seized in the dies and ultimately breaks in the dies. When this occurs, the extruding operation must be suspended until the broken wires are removed, the extrusion dies cleaned and a new length of wire inserted in the extrusion dies. This problem is particularly acute in high speed wire insulating operations where the wire passes through the extrusion dies at several thousand feet per minute and ever more acute where a continuous overall annealing and insulating line is used.

Accordingly, it is the primary purpose of the instant invention to provide an improved method for producing covered wire, such as insulated electrical conductor wire, from previously uncontrolled atmosphere annealed wire,

wherein the wire, including the objectionable dry oxide surface coating, is controllably and evenly lubricated in an improved fashion prior to introduction of the treated wire into an extruding die used to apply a covering or jacket to the wire.

This and other purposes and advantages of the instant invention will become more apparent from a review of the following detailed description when taken in conjunction with the appended drawings, wherein:

FIG. 1 is a schematic perspective view of a suitable continuous production line for manufacturing an insulated electrical conductor and wherein certain stations in the said line embody the subject matter of the instant invention; and

FIG. 2 is an enlarged longitudinal sectional view taken generally along line 22 of FIG. 1 and illustrates in more detail certain of the equipment used in carrying out the process of the instant invention.

Although this invention will be described with particular reference to insulating aluminum and aluminum alloy conductor grade wires wherein the lubrication of such wires, including the objectionable oxide surface coating thereon, is effected prior to applying insulation to such wires, it will be understood that the teachings thereof are applicable to lubricating and covering other wire materials where problems may exist similar to those overcome by the instant invention.

With further reference to the drawings and in particular FIGS. 1 and 2, a preferred form of apparatus that can be used in carrying out the teachings of the instant invention generally comprises a continuous production line indicated at 10 and made up of a series of wire processing stations or zones including a heater or annealing zone 12, a lubricating zone 14, a covering applying zone 16 and a cooling zone 18 through which the covered aluminum or aluminum alloy conductor grade wire 20 passes prior to being wrapped about a takeup reel. The wire is initially unwound from a payoff reel 22 at the beginning of the line and it is finally coiled around the takeup reel 24 at the end of the line.

The payoff and takeup reels 22 and 24 can be driven by any suitable means (not shown) so that the bare annealed wire 20 can be properly unwound from the reel 22 and the final insulated or covered wire product 21a wound in a taut condition about its reel 24. As the previously drawn and bare wire 20 is unwound from reel 22, it passes through an uncontrolled atmosphere annealing zone or device 12. An uncontrolled annealing device or zone is desirable for cost reasons since a controlled annealing atmosphere zone involves expensive, complex equipment as well as continuous exact control of the equipment. Located in zone 12 is any appropriate heating device for raising the temperature level of the wire 20 being annealed to between 400 and 600 F. The wire in a continuous line of the type proposed can move through the annealing zone at several thousand feet per minute, for example, 2,000 feet per minute, and after leaving the annealing zone is cooled, such as by the air surrounding the line 10 or by contact with a liquid coolant.

In the case of drawn electrical conductor grade aluminum and aluminum alloy wire, wherein the diameter may be on the order of from .060 inch to .162 inch, the wire prior to annealing will usually be between half to full hard temper in accordance with customary drawing practices prevailing in the aluminum industry and have an ultimate tensile strength of between 18,000 to 29,000 psi. and a 1% to 3% elongation property based on a 10 inch length of wire. This elongation property, however, is not satisfactory for later use of the wire, for example, as housing wire, and must be at least partially annealed to'improvethis .elongation property. As a result of the annealing or partial annealing performed in zone 12, the wire will still retain an advantageous ultimate tensile strength of from 15,000 p.s.i. to 17,000 p.s.i. and now possessesa to elongation in 10 inches, the latter of which is highly desirable for later use of the wire where the wire may have to be severely bent or twisted during its use in a building or home.

As the aluminum or aluminum alloy wire passes through thisannealing zone 12, any lubricant previously applied to the wire, such as during prior drawing of the wire, becomes vaporized thereby leaving a dry oxide coated wire that is also frequently covered by a varnish film or residue. Accordingly, unless the annealed oxide coated ,wire surface is properly lubricated, galling problems will be encountered in the later insulating covering operation, wherein an insulating covering is extruded upon the wire. Forthe purpose of controllably lubricating the wire, the wire is next advantageously passed through a lubricating station or zone 14. In a preferred embodiment of the invention, station 14 can comprise a base element 30 for supporting a hollow lubricant distribution ring 32 located in a preferably closely spaced relation to and adjacent the forward portion of the support means 34 used to mount a lubricant distribution die 36. The lubri cant ring 32 is provided with a series of circumferential openings or orifices 40 through which the lubricant can be forced under pressure onto wire 20. The openings 40 can, if desired, be disposed at an angle relative to the front face of the lubricant distribution die 36 so that the individual jet streams of lubricating oil of the usual mineral base type converge to form a wire surrounding spray or mist preferably immediately adjacent the front face-of the die 36 in the manner generally indicated by the broken lines in FIG. 2. The lubricating oil is continuously supplied to the ring 32 through the medium of an appropriate hydraulic circuit schematically shown in FIG. 1 wherein a pump 42 is series connected to a supply conduit 44. One end of conduit 44 is connected to a reservoir 46 and the other end of conduit 44 is connected in a suitable fashion to the hollow interior 38 of the ring 32.

The ring 32 is rigidly connected to the bottom of the base member 30 by a stem element or rod 48. Rod 48 can be provided with an anchor flange 50 adjacent its lower extremity and the lower extremity of rod 48 can be inserted in an appropriate opening in base member 30 and then welded in place. The top of base element 30 has surrounding and interconnecting sidewalls 52, the purpose of which is to trap and collect excess lubricant which does not adhere to the wire as well as lubricant removed from wire by die 36 and thereafter return all such lubricant through the bottom of base element by way of a conduit 54 to reservoir 46. It is evident that the ring 32 with the transverse openings therein advantageously supplies a continuous wire encircling conical spray or flood oil having its vertex located substantially immediately adjacent the front face of the die 36 by virtue of the hydraulic circuit aforedescribed.

The support 34 for the lubricant distribution die 36 can be a solid block, the bottom face of which is afiixed in any well-known manner to base element 30. The support 34 has a stepped opening 56 therethrough for the purpose of mounting the lubricant distribution die 36 in the manner shown.

.,Die 36 is preferably mounted within the larger part of the stepped opening 56 in any suitable fashion, such as by set screws (not shown). The die 36 includes an orifice 58 which is advantageously of a size and con figuration corresponding to but only slightly smaller than the size and configuration of the wire 20 prior to annealing. This difference, for example, can amount to from about a 0.001 of an inch to a 0.002 of an inch difference between the diameter of die orifice 58 and the diameter of wire 20 prior to its being anneal Th slight diameter difference which results in only a minimal drawing of the wire in orifice 58., at the same time provides for controlling and efiectively lubricating the entering wire 20 including the oxidized surface thereof and causes the lubricant to be evenly distributed about the wire surface. Moreover, because of the small difference in the aforesaid diameters of wire 20 and orifice 58, die 36 does not appreciably work harden the wire to the point where the previously built-in and enhanced elongation properties of the wire resulting from annealing are seriously affected. When the die opening 58 is smaller in diameter by 0.001 inch than the diameter of the starting and unannealed wire 20 and with the wire to be annealed being, for example, of 0.060 inch gauge, the die orifice 58 would be in the neighborhood of about 0.059 inch in diameter. In short, in practicing the instant invens tion, the size of orifice 58 of die 36 .should be such in relation to the size of wire being treated that while effectively distributing a relatively even film of lubricant about the wire including the dry oxide coating thereon, orifice 58 will at the same time, for all practical pur poses, produce only a negligible drawing of the wire-and a removal of minor or small amounts of the oxide coating.

Because of the negligible wire drawing effected in the case of an electrical grade aluminum and aluminum alloy conductor wire, which has been annealed and then subjected to the aforesaid lubricating operation, the elongation property of such wire is decreased by about only 1% per thousandth inch of diameter reduction which in effect is also a 1% elongation percentage property decrease from the original elongation percentage property of the annealed wire. Thus, if the elongation percentage property of the wire 20 after annealing and prior to being lubricated and passed through die 36, is between 10% to 15 and a loss of 1% elongation occurs during lubrication of the wire as aforesaid, the final covered wire product will still have a desirable 9% to 14% elongation property. All of the aforesaid percentages have been based for the purpose of illustration on drawn, annealed, lubricated and finally covered electrical grade aluminum or aluminum alloy wires of 10 inches in length and of diameters on the orders of from 0.060 inch to 0.162 inch.

The lubricant from ring 32 not only lubricates the wire 20 but also acts as a flushing oil for removing oxide particles both from the die 36 and wire 20. After being treated in zone 14, the lubricated wire, now identified by reference numeral 21, is passed to the covering zone 16. A relatively thin but continuous oil film of relatively uniform and even thickness will thus adhere to the wire after passage through die 36 and this film acts as a renewed lubricant for the wire during its passage through the extrusion press or covering zone 16. In the event the operation is of the continuous type shown in FIG. 1', the wire would not only be passed uninterruptedly and directly from zone 14 to zone 16 but also uninterruptedly and directly from zone 12 to zone 14.

Zone 16 includes a housing 58' provided with a suitably heated chamber 60 in which a guide tube 62 provided with opening 63 and an extruding die 64 are positioned. The upper end of chamber 60 is adapted to receive a conventional extrusion screw or a ram 66. The rod end of ram 66 is activated by a suitable means (not shown) so as to force the usual plastic insulating material 68 I made, for example, of polyvinyl chloride, through the extruding die 64 in timed relation with the speed of the lubricated wire 21 passing through die 64. The guide tube 62 is inserted into an openingat the left end of the housing 58 as shown in FIG. 2 and this tube 62 is provided with a tapered longitudinal opening 63, the smallest crosssection of which is slightly larger than the size of the lubricated wire 21 so as to permit free passage of the. wire passing therethrough. As shown in FIG. 2, the extrusion die 64 is located at the right end of the housing 58' and it is aligned with tube 62. Die 64 has a frusto-conical orifice 65 that terminates in a final cylindrical opening 70 at its outer end. The relative difference in size between the final opening 70 and the smallest cross-section of opening 63 is such that the smaller portion of opening 63 permits free passage of the lubricated wire 21 while the larger opening 70 permits the desired application of plastic insulating material or the like of a uniform thickness onto wire 21. Thus, as the lubricated wire 21 is fed through the extrusion press 16, the force applied to the ram 66 coupled with an appropriate heating means surrounding the chamber 60 assures proper application of the covering or jacketing material to the lubricated wire 21. Although the chamber 60 is heated, the elevated temperature of chamber 60 is not so high as to have any appreciable effect on the wire so as to cause a measurable further annealing of the same. After passage through the extrusion press, the final wire product now identified by reference numeral 21a and carrying the final covering 28 is passed across gap 28' and through the cooling station 18 where it is cooled to room temperature so that the extruded covering or jacket 28 will set and thereby retain its desired extruded shape in the final wire product 21a.

Further advantages resulting from utilization of die 36 in combination with the guide tube 62 are that the die 36 acts to center the wire 21 relative to extrusion press 16 as well as to straighten the wire 217 This centering assures that the thickness of the insulation covering at any point around the circumference of the final covered wire product 21a will be relatively uniform within prescribed production tolerances. Thus, for example, a solid 0.081 inch final diameter of wire can have a relatively uniform $4 inch wall of polyvinyl chloride insulation applied thereto. In order to achieve the centering and straightening, the drawing die 36 and guide tube 62 are preferably spaced relatively close together by the short gap 28'.

An advantageous embodiment of the invention has been shown and described. It will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the spirit and scope thereof as set forth in the appended claims, wherein what is claimed is:

1. A method for producing insulated conductor wire from wire that has been previously annealed in an uncontrolled atmosphere comprising the steps of continuously feeding an uncontrolled atmosphere annealed wire to a lubricating zone; and while advancing said wire through said zone, applying a lubricant to the wire, and then passing the wire through a die orifice the diameter of which is slightly less than the diameter of the wire in its preannealed state so as to controllably and uniformly distribute the applied lubricant about the wire surface including the oxide coating formed on the surface of the wire as an incident to the annealing thereof, and during said passage through said die orifice permitting a slight reduction in the diameter of the wire to take place, but without at the same time appreciably work-hardening the wire and while decreasing the enhanced elongation properties of the wire obtained by the annealing of said wire by about 1% per thousandth inch of diameter reduction; and thereafter transferring the lubricated wire to a wire insulation covering zone within which is disposed a further die orifice used to apply insulation to the wire and then passing said wire through said last die orifice and applying insulation to said wire.

2. The method as set forth in claim 1 wherein a decrease in diameter of the preannealed wire of about 0.001 inch is effected during passage of the wire through the first die orifice.

3. The method as set forth in claim 1 wherein a minor amount of work hardening of the wire is effected during passage of the wire through said first die orifice such that the elongation property of the annealed wire as expressed in terms of a percentage in ten inches of wire length is decreased by about 1%.

4. The method as set forth in claim 1 wherein said wire to be lubricated and covered is selected from the group consisting essentially of aluminum and aluminum alloys.

5. The method as set forth in claim 1 wherein the wire passes from the lubricating zone uninterruptedly and directly into the wire covering zone.

6. The method as set forth in claim 1 wherein the wire is passed through said first die orifice without at the same time appreciably disrupting the oxide coating previously formed on the surface thereof.

7. A method for producing an insulated conductor wire from wire which has been previously annealed in an uncontrolled atmosphere so as to provide a final insulated conductor wire having between a 9% to 14% elongation property as expressed in terms of a percentage in ten inches of wire length comprising the steps of continuously feeding an uncontrolled atmosphere annealed wire having a 10% to 15% elongation property in ten inches of wire length to a lubricating zone; and while advancing said wire through said zone, applying a lubricant to the wire, and substantially immediately thereafter passing the wire through a die orifice the diameter of which is slightly less than that of the wire in its preannealed state so as to controllably and uniformly distribute the applied lubricant about the wire surface, and during said passage through said die orifice permitting a slight reduction in the diameter of the wire to take place, but without appreciably work hardening the wire, and while slightly decreasing the said 10% to 15% elongation property in ten inches of wire length obtained by annealing whereby the lubricated wire will possess a 9% to 14% elongation property in ten inches of wire length; and thereafter directing the lubricated wire directly to an insulation application zone within which a further die orifice is disposed and then passing said lubricated wire through said further die orifice and applying insulation to said wire in said last mentioned zone.

8. A method as set forth in claim 7 wherein the wire is fed successively and uninterruptedly through the lubricating and insulation application zones.

9. A method as set forth in claim 7 wherein said wire to be lubricated and insulated is selected from the group consisting essentially of aluminum and aluminum alloys.

10. A method as set forth in claim 7 wherein said wire to be lubricated and insulated is selected from the group consisting essentially of aluminum and aluminum alloys and wherein a decrease in diameter of the preannealed wire of about 0.001 inch is effected during passage of the wire through the first die orifice.

11. A method as set forth in claim 7 wherein the wire is at least partially annealed in an uncontrolled atmosphere annealing zone prior to being lubricated and wherein said wire is successively and uninterruptedly advanced through said annealing zone, said lubricating zone and said insulation application zone.

References Cited UNITED STATES PATENTS 1,896,674 2/1933 Longwell 72-463 2,029,039 1/ 1936 Simons 7243 2,109,312 2/1938 Dimmick 72463 2,502,471 4/ 1950 McIlvried 72463 2,872,027 4/1959 Johns et al. 7243 2,928,164 3/1960 Span 72-39 3,093,897 6/1963 Lemyre et al 72-39 PAUL M. COHEN, Primary Examiner U.S. Cl. X.R.

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