Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
The invention relates to magnet wire and a method
and apparatus for manufacturing magnet wire, and more
particularly, to a method and apparatus for applying a
coating of flowable resin material on a continuously
moving filament to a desired thickness in a single
pass.
Magnet wire has been conventionally manufactured by
passing a bare copper or aluminum conductor or a
previously insulated copper or aluminum conductor
through a bath of liquid enamel (a solution of resin
material in a solvent thereof) and through an oven for
driving off the solvent from the enamel and/or curing
the resin, leaving a resin coat on the conductor.
The application of a coat of materîal to a filament
from solution accounts for all of the magnet wire
manufactured today. While some materials using today's
technology can only be applied from solution, the cost
ox the solvent expended in applying resin materials from
solution is usually significant. The machinery used in
this process is also higly complex and expensive,
although the machinery cost is usually not a factor
since most of such machinery has been in use for a
considerable number of years. Still the original cost
of such machinery is significant for new installations
In addition to the cost of machinery and the solvent
expended by such a process, there is the cost of
providing and maintaining pollution control equipment;
since recently both Federal and State laws have required
that the oven stack gases of such machines be
essentially stripped of solvent beEore exhausting the
gases to the atmosphere While various methods of
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burning the vaporized solvent and/or reclaiming the
solvent have been proposed, all such methods result in
further expense to the manufacturer.
Additionally, the application of a layer of
material to a filament from solution usually requires
several successive coats in order to result in a
concentric coat of a desired thickness. For example,
six coats may be required for a 3 mil coating, although
in specific applications as many as 24 coats have been
required. Also, multiple coats of certain materials
cannot be applied successfully from solution due to a
lack of good adhesion and wetting between coats.
It therefore has been desirable for some time to
provide an improved method of manufacturing magnet wire
which eliminates the use of solvent. Also, it would be
additionally highly desirble to provide an improved
method of manufacturing magnet wire which would utilize
an apparatus of simple design. Also, it would be highly
desirable to provide a method of manufacturing magnet
wire which would allow the wire to be drawn coated and
spooled in a continuous operation; conventionally the
wire is drawn, annealed if necessary, spooled; and then
coated and spooled again for shipment. Additionally, it
would be highly desirable to provide a method and
apparatus which can successfully apply multiple layer
of materials which have heretofore not been possible.
Finally, it would be highly aesirable to provide an
improved method and apparatus for manufacturing magnet
wire which would not require the use of solvent or
pollution control apparatus, or be limited to materials
requiring an oven cure, or require multiple coats to
obtain a coating of the required continuity and
concentricity.
Applying coatings of resinous material by extrusion
is substantially less common than applying coatings from
solution, since conventional extrusion processes are
extremely limited. Coatings of 4 mils and less are
either extremely difficult to apply or impossible to
apply by conventional extrusion processes. Also, the
number of materials which are successfully applied by
conventional extrusion processes are extremely limited.
Polyvinyl chloride, polyethylene, polypropylene and
various elastomeric rubbers comprise 99% of the
materials applied by extrusion. These materials are not
used in a true magnet wire application, ire. an
electrical winding, the turns of which are insulated to
provide low voltage, mechanical and thermal protection
between turns, and do not possess magnet wire
properties. In contrast, these materials are
conventionally used in lead wire or hook-up wire
applications which must protect against the full imput
line voltage of an electrical device. Conventionally,
extrusion is used in the production of only cables,
building wire, and lead or hook-up wire.
While the apparatus used in conventional extrusion
processes is relatively simple when compared to a
conventional wire coating tower, and the extrusion
process can be carried out continuously whereby the
filament may be drawn, coated and spooled in a
continuous operatlon, still, a conventional extrusion
apparatus is not without problems. Conventional
extruders include a centering die, a material reservoir
and a sizing die. The centering die mechanically
centers the filament in the sizing die, the sizing die
determines the exterior dimensions of the coated
filament and the thickness of the coat applied to the
filament. The primary problem associated with extrusion
apparatus is the wear on the centering die. Since the
centering die used to center the filament within the
sizing die, the centering die must be finely adjusted to
achieve a concentric coating and must be replaced
periodically due to the wear resulting from the contact
between the filament and the die. Centering dies tend
to be expensive even when made of hardened steel, but
because of the wear that occurs, diamond centering dies
have been considered, but not widely used.
Therefore -it would be highly desirable to provide
an improved method and apparatus for manufacturing
magnet wire which would have all of the benefits of an
extrusion process but none of the disadvantages. Such a
method and apparatus would lower the cost of the
machinery to manufacture magnet wixe and would eliminate
the need for solvent, lower manufacturing costs,
conserve raw materials and energy, eliminate the need
for pollution control apparatus, require less expensive
and simpler machinery than now is conventional, and
allow for continuous operation from wire drawing to
final shipment without being limited to materials
from solution or oven cures.
SUMMARY OF THE INVENTION
It is therefore a primary object of this invention
to provide an improved method and apparatus for
manufacturing magnet wire.
It is another object of this invention to provide
an improved method and apparatus for manufacturing
magnet wire which does not require solutions of
insulation material and thereore eliminates the need
for solvents pollution control equipment or for
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reclaiming solvents from the manufacturing process,
lowers the cost of manufacturing at least proportionally
to the cost ox solvent, and conserves energy at least to
the degree what energy is required to remove solvents
from the insulation material.
It is also another object of this invention to
provide an improved method and apparatus for
manufacturing magnet wire which is not limited to the
use ox insulation material solutions or materials
requiring curing after application.
It is another object of this invention to provide a
method and apparatus for manufacturing magnet wire which
does not require multiple coats to obtain the required
concentricity and/or continuity.
It is another object of this invention to provide
an improved method and apparatus for manufacturlng
magnet wlre in which a coating materîal Jan be applied
to a continuously moving elongated filament to a desired
thickness in a single pass.
It is another object of this invention to provide
an improved method and apparatus for manufacturing
magnet wire my which magnet wire can be manufactured at
speeds which are limited only by filament pay-off and
take-up devices
It is another object of this invention to provide
an improved method and apparatus for manufacturing
magnet wire by which a coat of resin material may be
applied to an elongated continuously moving filament to
a desired single thickness in a single pass whereby the
filament may be drawn or otherwise formed/ coated and
spooled in a continuous operation.
It is another object of this invention to provide
an improved method and apparatus for manuacturing
S'~ [3
magnet wire which completely eliminates or substantially
reduces the use of solvents thereby eliminating the cost
of solvents and the need for pollution control equipment
or to reclaim the solvents from the manufacturing
proces 5 .
It is another object of this invention to provide
an improved method and apparatus for rnanufactur.ing
magnet wire which completely eliminates the need of
highly complex machinery or dies which experience high
wear and must be replaced periodically.
It is another object of this invention to provide
an improved method and apparatus of manufacturing magnet
wire which has all of the advantages of a conventional
extrusion process but i5 not limited in the thinness of
the coating applied to the filament by such a process.
It is another object of this invention to provide
an improved method and apparatus for manufacturing
magnet wire having all of the advantages of a
conventional extrusion process but none of the
disadvantages.
In the broader aspects of the invention, there is
provided a novel method an apparatus for manufacturing
magnet wire in a continuous process by which coatings of
a flowable resin material may be applied concentrically
to a moving elongated fil ment in thicknesses of about
16 mils or less. The filament can be a bare copper or
aluminum conductor having round or rectangular
configuration ox an insulated conductor upon which a top
or an intermediate coat of material is desirably
applied Coatings of one-half mil and one mil also can
be applied by the method of the invention D By the
method and apparatus of he i.nvention, magnet wire can
be manufactllred by continuously drawin9 the wire to
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size, annealing -the wire, if necessary, insulating the wire
wi-th one or more coa-ts of flowable resin material, curing the
resin material, if necessary, hardening the resin ma-terial,
and spooling the wire for shipment, wi-thout interruption a-t
speeds limited only by -the filament pay-off and -take-up devices
used. The apparatus oE the invention utilizes the flowable
resin material to center the filamen-t in a die, -the size of
the die controls the thickness of the coat to be applied. In
the apparatus of the invention, only the resin material beiny
applied to the filament is in contact with the filament. Thus,
the mechanical wear normally associated with centering dies
used in extrusion processes and like devices is completely
eliminated. Further, -the apparatus and method of -the invention
can be used to apply coats several times thinner than is
possible with conventional extrusion apparatus and of materials
different than those conventionally extruded onto filaments.
In specific embodiments using heat softenable materials or
melts, curing is no longer required; and -thus, the need for
curing, ca-taly-tic burners and the like as well as all concerns
regarding atmospheric pollution are eliminated The coa-ted
filaments and magnet wire made by the apparatus and in accord-
ance with the method of the inven-tion have coatings which are
surprisingly conce~ricand continuous when compared to magnet
wire made by conventional methods and apparatus
In accordance wi-th the present invention, there is
provided a method of manufacturing magnet wire in which a
flowable bu-t hardenable matexial is applied to an elongated
conductor to a desired thickness in a single pass whereby
said conduc-tor may be drawn or otherwise formed, coated and
spooled in a continuous operation comprising the s-teps of:
a. passing said conduc-tor -through a stationary
entrance die at a speed in excess of 100 fee-t per minute,
,
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b- passing said conduetor through a stationary
exit die at a speed in excess of 100 feet per minute, said
exit die having a throat portion, an entrance opening larger
than said throat portion intereonneeted by a eonverging
interior wall -thereby defining a die eavity between said
throat portion and said opening and said conduc-tor and said
wall, said entrance die and exit die defining and partially
enclosing a die chamber therebetween, said eonductor in said
dies being spaced from said dies,
e. filling said die chamber with a flowable material
including less than about 5% weight solvent at a temperature
above the melting point thereof,
d. raising the pressure of said material within
said die ehamber above atmospheric pressure,
e. passing said eonduetor through said die chamber
thereby applying said flowable material onto said conductor,
f. centering said conductor in said throat portion
of said exit die solely with said material in said die chamber,
g. wiping the exeess of said material from said
eonduetor leaving an essentially eoneentric coat of said
ma-terial on said conduetor of a thickness meeting the
requirements of ANSI/NEMA Standards Publication No. MW1000-1977.
In accordance with another aspect of the invention,
there is provided an apparatus for the manufacture of magnet
wire eomprising a die apparatus, a filament pay-out deviee,
a eoated filament take-up deviee, said die apparatus being
loeated between said pay-out and take-up deviees, said die
apparatus including entrance and exit dies and a die block,
said die block being between said dies, said entrance die
having a throat portion, an entrance opening larger than said
throat portion intereonnected by a converging interior wall
- 9a -
-.,!,~. ',
so
and an exi-t opening larger than said -throat portion inter-
connected by a diverging interior wall, said exi-t die haviny
a throa-t portion, and an entrance opening larger than said
throat portion in-terconnected by a converging interior wall,
said die block having an interior passage communicating wi-th
said exit opening of said entrance die and said entrance
opening of said exit die, thereby defining a die chamber
between said diverging interior waLl and said passage and said
converging interior wall, said entrance and exit dies being
positioned to receive a filamen-t trained between said pay-out
and take-up devices in said openings and tnroat portions
thereof; a reservoir of flowable but hardenable material, means
operatively connected to said reservoir for filling said
central die chamber with said material and maintaining said
material wi-thin said die chamber at elevated pressures, and
means including said ma.terial in said die chamber for cen-tering
said filament in said throat portion of said dies.
In accordance with another aspect of the invention,
there is provided an apparatus for the manufact:ure of coated
filaments such as magnet wire comprising a die apparatus, said
die apparatus including entrance and exit dies and a die block,
said die block being between said dies, said entrance die
having a throat portion, an entrance opening larger than said
throat portion interconnected by a converging in-terior wall and
an exit opening larger than said throa-t portion interconnected
by a diverging interior wall, said exit die having a -throat
portion, and an entrance opening larger than said throat
portion interconnected by a converging interior wall, said die
block having an in-terior passage communicating with said exi-t
opening of said entrance die and said entrance opening of said
exit die thereby defining a flowable material centering
- 9b
- . "
5~3
chamber between said diverging interior wall and said passage
and said converging interior wall.
In accordance with another aspect of the invention,
there is provided an apparatus for the manufacture of coated
filaments such as magnet wire comprising: a bare filament
pay-out device, a coated filament take-up device, and a die
apparatus loca-ted between said pay-out and take-up devices,
said die apparatus including entrance and exit dies and a
die block, said die block being between said dies, said entrance
die having a throat portion and an entrance opening and an exit
opening larger than said throat portion, said throat portion
connected to said entrance opening and interconnected by a
diverging interior wall to said exit opening, said exit die
having a throat portion and an exit opening and an entrance
opening larger than said throat portion interconnected by a
converging interior wall, said die block having an interior
passage communicating wi-th said exit opening of said entrance
die and said entrance opening of said exit die, thereby
defining a die chamber between said diverging interior wall
and said passage and said converging interior wall, an
applicator means, connected to a reservoir of coating material,
for filling said die chamber with said coating material at a
desired pressure, upon said filament entering said die
apparatus said converging interior wall providing a surface
adjacent to which said material creates a support of coating
material such that the filament does not contact the die
and the filament it centered in said die throats and forms a
continuous and concentric layer of coating material on said
filament.
BRIEF DESCRIPTION OF TIIE DRAWINGS
The above mentioned and other features and objects
, . .
5~7~
of this invention and the manner of attaining them will
become more apparent and the invention itself will be
- 9d -
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best ~lnderstood by reference to the following
description of the invention taken in conjunction with
the accompanying drawings wherein:
Fig. 1 is a perspective, fragmentary and
diagramatic view of the apparatus of the invention;
Fig. 2 is a cross sectional view of the coating die
of the invention, taken substantially along the Section
Line 2-2 of Fiy. 1;
Fig. 3 is a front plan view of the coating die of
the invention taken substantially along the Section Line
3-3 of Fig. 1; and
Fig. 4 is a cross-sectional view of the coating die
of the invention taken substantially along the Section
Line 4-4 of Fig. 2.
DESCRIPTION OF A SPECIFIC EMBODIMENT
., . - _
APPARATUS
Referring to the drawings, and specifically Fig. 1,
the apparatus of the invention will be descried. The
apparatus 10 generally consists of a filament pay-out
device 12, a filament heater 14, a coating material
dispenser 16, a coating die 18l a hardener 20, and a
filament take-up device 22. As shown in Fiy. 1, the
filament 24 is broken at 26, at ~B, and at 30 . At the
filament break 26, when the apparatus of the invention
is used to manufacture magnet wire, conventional wire
drawing apparatus may be insertedO Thus, an oversized
filament 24 may be reduced to the desired size by the
drawing equipment prior to coating the filament. The
filament heater 14 in a specific embodiment in which
magnet wire is being manufactured by the apparatus of
the invention may include an annealer whereby the
4S7~
effects of drawing the wire or stretchlng the wire may
be eliminated. In other specific embodiments in which
magnet wire is being manufactured by the apparatus of
the invention, additional coating dies 18 and hardeners
20 may be inserted at 28 such that successive coats of
different coating materials may be applied to the
filament in a continuous manner.
The term "filament" is used herein for all strand
materials. Filaments thus include both copper and
aluminum conductors and insulated copper and aluminum
ronductors which prior to the application of a coat of
material by the apparatus and method of the invention
have been insulated with a base coat of insulating
material, a tape of insulating material either spirally
or longitudinally wrapped on the conductor, or other
conventional insulating materials, and other strand
materials desirably coated. While the specific
embodiments herein descrlbed primarily relate to the
manufacture of magnet wire, the apparatus of the
invention is thought to-have-utility in coating all
sorts of filaments other than conductors or insulated
conductors in the production of magnet wire.
The term "10wable materiall' is used herein for the
general class of coating materials applied by the method
and apparatus of the invention Again, while the
specific embodiments herein described refer to meltable
coating materials which can be hardened by cooling the
material to ambient temperatures, other coating
materials which are flowable at elevated temperatures
and pressures are contemplated as being within the
general class of materials which can be applied by the
method and apparatus of the invention. These materials
include materials which are initially flowable but later
5~
hardened by curing or the~mosetting the material and
also coating materials which may include up to about 5%
by weight ox solvent to render them flowable and later
hardenable by driving the solvent from the material. In
the manufacture of magnet wire, several different
materials can be applied by the method and apparatus of
the invention. These include but are not limited to
polyamides such as Nylon, polyethylene terephthalates,
polybutylene terephthalates, polyethylenes,
polyphenylene sulfide, polycarbonate~, polypropylenes,
polyethersulfone, polyether imides~ polyether
etherketone, polysulphonesl epoxys, flurocarbons
including ethylene-chlorotrifluoroethylene and hylene
tetrafluoroethylene polyvinyl formal, phenoxys,
polyvinyl butyrol, polyamide-imide, polyesters and
combinations thereof.
The filament pay-out device 12 includes a spool 32
on which the filament 24 desirably coated is stored.
The spool 32 is mounted on spindle 34 of the pay-out
device 12 so as to freely rotate in the direction of the
arrow 36. Operatively associated with the spool 32 is a
brake 3~ which restrains the rotation of the spool 32 as
the filament 24 is being pulled therefrom by the taXe-up
device 22 so as to prevent entanglements. In accordance
with the method of the invention, it is highly possible
that in a magnet wire manufacturing plant where
conductors are being rolled, drawn or otherwise reduced
in size to desirable conductor from ingots, the pay-out
device 12 can be completely eliminated, since the
remaining apparatus can be used to coat conductors
continuously in a single pass as the conductor is
supplied from such rolling and drawing apparatus The
reels 32 in this instance can be the reels upon which
bar copper and aluminum conductors are now transported
from the rolling and drawing operations to the magnPt
s~3
wire manufacturing plants. In all instances where the
take-up device 12 is eliminated and rolling and drawing
operations are substituted therefore, an annealer is an
essential part of the apparatus in order to eliminate
the effects of working the conductor during the rolling
and drawing operations.
Filament heater 14 is an essential part of the
apparatus of the invention to be used in the performance
of the method of the invention. A filament heater may
be used solely to raise the temperature of the filament
prior to the application of the coating material or may
be an annealer if hard bare wire is used or to further
reduce the effects of the aforementioned rolling and
drawing process, if required. Thus, in a specific
embodiment, the filament heater 14 may consist of an
annealer, or may consist ox a filament heater. In the
specific filament heater embodiment 14 illustrated in
Fig. 1, the filament heater comprises a resistance coil
40 being generally tubular in shape and having opposite
open ends 42 and 44. The filament or conductor 24 is
trained between the pay-out device 12 and the tàke-up
device 22 through the coil 40. The filament heater 14
is also provided with a control 46 by which the
temperature of the conductor 24 can be controlled. The
filament heaver 14 may also include a filament
temperature measuring device such as a radiation
pyrometer. Hereinafter in specific examples, the
approximate wire temperatures reported herein are
measured by such a device.
The coating die 18 is illustratecl in Figs. 1
through 4. The coating die 18 includes an entrance die
61, an exit die 62 and a die block 64. entrance die 61
is mounted in the forward portion of die block 64 by
5~7(3
screws 66. Exit die 62 is mounted in the rearward
portion of die block 64 by screws 66'. Separating
entrance die 61 and exit die 62 is an interior passage
65. Die block 64 is provided with heater bores 68 in
which heaters 70 are positioned. In a specific
embodiment, etch heater 70 may be a tubular calrod
heater. Additionally, the die block 69 is provided with
a thermocouple bore 72 therein in which a thermocouple
74 (shown only in Fig. 4) may be positioned.
Furthermore, die block 64 is provided with a nozzle bore
75 therein to which the nozzle 54 of material applicator
16 is connected. Hereinafter die temperatures are
reported with regard to specific examples; these die
temperatures are measured by thermocouple 74~ Heaters
70 are connected by suitable conductors to a heater 76.
seater 76 i5 provided with paired controls 78 whereby
the temperature of the entrance vie 61 and the exit die
62 each can be elevated above ambient temperature (for
each die) and controlled, respectively, as desired.
eferring to Fig. 2, the entrance die 61 is shown
in cross-section to include an entrance opening 80, a
throat 82 and a converging interior wall 84 which
interconnects the throat 82 and the entrance opening 80
of the entrance die 61. Entrance die 61 also has an
exit opening 86 and a diverging interior wall 88
interconnecting the throat 82 and the exit opening 86.
In a specific embodiment, the entrance die 61 can he
constructed as illustrated in a two-piece fashion hazing
a central piece 90 including a throat portion of harder
and more wear-resistant material, and exterior piece 90
which includes both the entrance opening 80 and the exit
opening 864
570
The exit die 62 is also shown in Fross-section to
include an entrance opening 92, a throat 93 and a
converging interior wall 94 which interconnects the
throat 93 and the entrance opening 92 of the exit die
62. Converging interior wall 94 partially defines a die
chamber 9S as will be mentioned hereinafter. Exit die
62 also has an exit opening 96 and a diverging interior
wall 97 that interconnects the throat 93 and the exit
opening 96. In a specific embodiment, the exit die 62
can be constructed as illustrated in a two-piece fashion
having a central piece 98 including a throat portion of
harder and more wear resistant material than the
exterior piece 98' which includes both the entrance
opening 92 and exit opening 96.
In a specific embodiment, the converging wall 84
and 94 define an angle A with conductor 24 of about 5 to
about 40 degrees and throats 82 and 93 are tapered from
converging walls 84 and 94 to diverging wall 88 and 97
so as to define an angle with the conductor 24 of about
.
1 to about 2 degrees.
The flo~able material applicator 16 has a chute 48
by which the material is supplied to the applicator, a
material reservoir 50 in which the material may be
stored, and a positive displacement pump 52 which
pressurizes reservoir 50 and dispenses the flowable
material through a nozzle 54. When using melts or other
temperature responsive flowable materials, reservoir 50
is provided with a heater and a control device 56 by
which the temperature of the material in the reservoir
can be controlled. An additional control device 58 is
associated with the positive displacement pump 52 to
control the amount of flowable material passing through
nozzle 54. In a specific embodiment, the fluid material
applicator 16 may be an extrusion apparatus having the
features above described. In those applications in
which the flowable material is rendered more flowable by
the use of a small portion of solvent, both the coating
material and the solvent may be fed into the applicator
via the chute 48 and the reservoir 50 may be provided
with a mixing apparatus having associated therewith a
separate control 60.
The central die chamber 95 is completely defined by
the diverging wall 88 of entrance die 61, the converging
interior wall 94 of exit die 62, and the walls of
interior passage 65 of die block 64. Die chamber 95 is
positioned between throat 82 and throat 93. The nozzle
54 is connected to nozzle bore 75 so that coating
material in reservoir 50 may be injected into the
central die chamber 99 under pressure by material
applicator 16. The filament or conductor 24 is trained
between the pay-out device 12 and the take-up device 22
through the entranee die 61, the central die chamber 95,
and the exit die 62~
The hardener 20 functions to harden the coat of
material on the filament or conductor 24 prior to
spooling the coated filament or magnet wire by the
take-up device 22. the hardener 20 as illustrated
includes a trough 100 having opposite open ends 102 and
104. The trough is positioned such that the filament or
conductor 24 can be trained to enter the open end 102,
pass through the trough 100j and exit the open end 104.
Also as shown, the trough 100 is sloped downwardly
toward the open end 102 and provided with a source of
cooling fluid, such as waxer 108~ adjacent open end 104
and a drain 110 adjacent open end 132. In many specific
embodiments, a water quench uti.lizing tne structure of -the hard-
ener 20 is desi:red. In other specific embodiments, a quench is
not required and thus, the cooling flllid is no-t used. In these
embodiments, ei-ther a flow of ambien-t air or rel-rigerated air
(where available) is trained on the coa-ted conductor or filament
24.
In specific embodiments in which multip]e coats of dif-
ferent materials are being applied to the filament or conductor 24
by successive spaced apart coating dies 18, the particular coating
10 die used depends on the material to be applied and maybe either
the coating die 18 having an entrance die 61 and an exit die 62
as disclosed herein or the coating die disclosed in united States
Patent No. 4,393,809. The particular coa-ting die used depends
on the material to be applied. Each of the coating dies will have
a material applicator 16 associated therewith and may have a hard-
ener 20 associated therewith. The term "coating station" is used
herein to refer to the assemblage of a material applicator 16, a
coating die, and a hardener 20. In these embodiments, there will
be a plurality of spaced apart coating stations between the pay-
20 out device 12 and the take-up device 22.
The take-up device 22 in many respects is similar to
the pay-out device 12. The take-up device 22 comprises a reel 32
on which the coated filament or conductor 24 is spooled for ship-
men-t. Thus reels 32 may be the conventional spools on which
coated filaments are conventionally shipped. Spools 32 are moun-t-
ed for rotation on a spindle 34 so as to be driven in the direc-
tion of the arrow 112. Operatively connected to the spool 32 is
a spool driver 114 which drives the spool 32 and -thereby pulls
the filament or conductor 24 from the spool or reel 32 of the pay-
out device 12.
i - 17 -
57C~
THE METHOD
The method of the invention will Dow be described.
Reference to Figs. 1 through 4 will be referred to and
the terms "flowable materialn and "filament" will be
used as above defined. This description of the method
of the invention will also specifically refer to the
manufacture of magnet wire in a single pass whereby the
filament or conductor is drawn or otherwise formed,
coated and spooled in a continuous operation.
A continuous supply of the filament or conductor 24
is provided either by the pay-out device 12 as
illustrated in Fig. 1 or from a rolling and drawing
operation. If supplied from a rolling and drawing
operation, the conductor 24 is always annealed to remove
all effects of the rolling and drawing operation.
The filament or conductor 24 is then heated, if
desired. Whether or not the filament 24-is héated is
dependant upon the coating material utilized and the
wire properties desired Thus, the filament 24 may be
heated by the heating device 14 to a temperature from
about ambient temperature to about the decomposition
temperature of the coating material. In most
applications utilizing a melt or a heat-responsive
flowable material in which the coat of material is
desirably adhered to the filament or conductor 24, the
filament or conductor is heated to a temperature from
just below to about the melting point of the coating
materialO In most applications utilizing a melt or a
heat-responsive flowable material in which the adhesion
of the coat of material to the filament or conductor 24
is not required, the filament or conductor 24 is
maintained from about the ambient temperature to
51 i~htly abov2 the ambient temperature
The central die chamber 99 is then filled with a
flowable material. The flowable material is stored in
the material reservoir 50 at a flowable temperature and
pressure and is injected into the central die chamber 99
by applicator 16. Once the central die chamber 99 has
been filled with material, the flowable material
contained therein ~7ill assume the pressure of the
flowable coating material in the reservoir 50. Pump 52
must have an adequate capacity to maintain pressures up
to about 2000 psi in reservoir 50 and chamber 99. By
control 58, the responsiveness to pressure changes
desired can be controlled. By controls 56 and 78, the
temperature of the material in the reservoir 50 and
chamber 99 can be controlled. The pressurized
temperature of the flowable material in the central die
chamber 99 must be carefully controlled for several
reasons. First, if the pressure and/or temperature of
the flowable material in the central die chamber 99 is
too great, the flowable coating material may have the
tendency -to leak in significant quantities from the
central die chamber 99 through throat 82, although the
filament passing through throat 82 will allow operating
pressures higher than that at which the flowable
material Jill leak from opening 80 when the filament is
stationary in opening 80. Any significant leakage of
flowable coating ma.erial from the die block 64 is not
preferred. Secondly, both the pressure and temperature
of the flowable material relate to the viscosity and/or
flow characteristics of the flowable material, and must
be such that the viscosity and/or flow characteristics
of the flowable material performs its centering function
relative to the exit die 62 and produces a concentric
coating as will be subsequently discussed, wets the
filament to be coated, and suitably adheres to the
filament. Thirdly, if the pressure and the temperature
of the flowable material is too low, excessive filament
stretching may occur from die 18 excessively resisting
the movement of filament therethrough. It is for these
reasons, that the applicator 1G is provided with
controls 56, 58, and 60.
The coating material is then applied to the
filament or conductor 24 by passing the same through die
1 a . The coating material within the die chamber
functions to center the filament or conductor 24 within
the throat portions 82 and 93 of dies 61 and 6~. In all
instances known to the applicants wherein the central
die chamber 99 is properly filled with coating material
115 and the temperature and pressure therein are
properly controlled, filaments or conductors 24 that are
coated by the method and apparatus of the invention have
a surprlsingly concentric and continuous coat of coating
material thereon. Conversely, in all situations in
which the central die chamber 99 is not properly filled,
anon the temperature and pressure therein is not
properly controlled, a non-concentric and discontinuous
coat of coating material is applied to the filament or
conductor 24. Thus, the proper filling of the central
die chamber 99 with coating material the control of the
temperature and pressure of the coating material therein
are essential to the method of the invention. Coating
materials of various types have teen successfully
applied in accordance with the method of the invention
by the above~described apparatus at viscosities from
about 5,000 cps to 200,000 cpsO
Applicant does not completely underskand the
actions of the flowable material within the central die
3~
chamber 99 which results in filaments having coatings of perfec-t
concentricity and continui-ty thereon. The coating material con-
tained within the central die chamber 99 is believed to have
movement adjacent the throat 83 of the exit die 62. This move-
ment may be somewhat similar to the movement of the annular or
toroidal support 120 as described in UuS. Patent No. 4,393,809.
The throat portion 82 of the entrance die 61 prevents
the flowable material within the die chamber 99 from leaking
from die 18 through die 61~ Depending upon the flow properties
of the coating material, throat portion 82 will have a diameter
of about 3 mil to about 15 mil larger than the diameter of fila-
ment 24.
The throat portion 93 of the exit die 62 regulates
the thickness of the coat of coating material left on the fila-
ment or conductor 24 exiting the coating die 18.
The size of the throat portion 93 of the exit die 62
varies in accordance with the size of the filament or conductor
24, and the desired thic]sness of the coat of coating material to
be applied thereon. The method of the invention has been
successfully used with filaments ranging from about 30 AW gauge
to about 3/8" rod. Conductors of rectangular cross-sections
and of other cross-sections can also be coated by the method and
apparatus of the invention so that as long as the throat por-
tions 82 and 93 of the entrance die 61 and exit die 62, respec-
tively, can be provided in a geometrically similar shape. Coat-
ings from about 1/2 mil to about 16 mils thick can be applied
by the method of the invention. Depending upon the Elow proper-
ties of the coating material, the throat portion 93 of the exit
die
5~C~
62 will have a diameter in most cases from about the
desired diameter to about 2 mils larger than the desired
diameter of the coated filament or conductor 24 of
magnet wire.
The coated filament or conductor 24 is then passed
through the hardener 20 in order to harden the coating
material thereon. While the structure of the hardener
20 and the function thereof has been described
hereinabove, it should be emphasized here that the
operation of the hardener 20 depends greatly upon the
coating material used. Either a water quench or an air
quench may be utilized. Additionally, in those flowable
materials in which small amounts of solvent are used to
aid in the properties of the flowable material, the
hardener 20 may take the form of a filament heater 14,
or a conventional curing oven (not shown). In all
cases, the type of hardener 20 utilized and the
temperature of the cooling liquid, air or other fluid
utilized will depend both on the coating material and
the speed at which the coated-filament passes through
the hardener 20.
The operation and function of the take-up device 22
was described hereinabove. However, the speed at which
the take-up device 22 was driven was not mentioned. The
driver 114 is not limited in any way by the method of
the invention. The speed at which the driver 114 drives
the spool 32 of the take-up device 22, in the embodiment
illustrated in Fig. 1 utilizing both pay-out 12 and
take-up 22 devices, is solely limited by the pay-out 12
and take-up 22 devices themselves when applying any of
the coating materials mentioned herein. When the
pay-out device 12 is eliminated and conventional rolling
and drawing operations are substituted therefore, the
speed at which the take-up device 2Z is driven by the
So
driver 114 is solely limited by the take-up device 22,
itself.
Specific examples in which conductors of various
sizes have been coated with coating material such as
above mentioned in accordance with the method of this
invention are tabulated in Table 1. Table 1 solely
relates to the production of magnet wire. Table 1
tabulates all of the essential properties of the coating
material and the conductor, all of the essential process
conditions, and all of the essential physical and
electrical properties of the magnet wire produced in
this specific example in accordance with the method of
the invention utilizing the apparatus described
hereinabove.
The magnet wire produced by the apparatus of the
invention in accordance with-the-method of the invention
meets all of the requirements of magnet wire made by
other existing commercial processes. Table 1 tabulates
the physical and electrical properties of various magnet
wires manufactured in accordance with the method of the
invention utilizing the apparatus of the invention. A
surprising characteristic of all magnet wires made in
accordance with the method of the in-~ention utilizing
the apparatus of the invention is the concentricity of
the coating applied to the conductor and the continuity
thereof. Both the concentricity and continuity are a
surprising result when compared to magnet wires made by
other existing commercial processes without regard to
the means by which the conductor or filament 24 is
centered within the coating die 18. Magnet wire
produced by other commercial processes, such as the
57~
application of coatings from solution, periodically result in
non-concentric coatings and non-continuous coatings. In fac-t,
the continuity of coatings applied from solution is such that
reliance upon a single coating of magnet wire insulation is
unheard of; and for this reason and others, multiple coatings
are used as above-mentioned.
Magnet wire having a single coat is a commercial
reality due to the concentricity and thickness of the coatings
that can be applied by the apparatus and method of the invention.
The invention provides an improved method and appara-
tus for applying coatings of a flowable material concentrically
to a moving elongated filament. In the manufacture of magnet
wire, the method and apparatus of the invention is an improve-
ment over conventional methods of manufacturing magnet wire.
By the invention, insulation can be applied to a continuously
moving elongated conductor, concen-trically, to a desired thick-
ness in a single pass. Materials can be applied by the inven-
tion which can not be applied by the method and apparatus dis-
closed in U.S. Patent No. 4,393,809 above mentioned. The speed
is limited only by the pay-off and take-up devices. The con-
ductor can be drawn or otherwise formed, coated, and spooled in
a continuous operation which completely eliminates or substanti-
ally reduces the use of solvents, thereby eliminating the cost
of solvents and the need for pollution control equipment. The
apparatus of the invention completely eliminates the need for
highly complex machinery or dies which experience high wear and
must be replaced periodically. The improved method and appara-
tus of the invention has all of the advantages of
2~
7~
a conventional extrusion process but none of the
disadvantages
While there have been described above the
principles of this invention in connected with specific
apparatus, it is to be clearly understood that this
description is made only by way of example and not as a
limitation to the scope of the invention.
457~ '
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