Note: Descriptions are shown in the official language in which they were submitted.
,~ r ~21942C~"' , !'
.
~AC~G20UND OF ~HE I~VENTION
_, . . .
Th~ invention relates to magnet ~ire 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 material 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
of 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 yearsO 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 before exhausting the
gases to the atmosphere. While various methods of
- 3 ~
r~ ~ 2~%~
burning the vaDorized solv~-nt and/or re~claiming the
solvent have been pro?osed, ~11 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 materiais
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 provi~e 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 layers
of materials which have heretofore not been possible.
Finally, it would be highly desirable 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.
` ' ~Z~L~420
~ ??-~ ~ coâtin9s of ~esinous ;raterial by e~tr~sion
is su~stlntially less com~on than apply`ing coatings from
sOlUtion, ~ince conventional extrusion processes are
extremel~ ited. Coatings of 4 mils and less are
either ext.e~ely 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.
~olyvinyl chloride, polyethylene, polypropylene and
various elastomeric rubbers comprise 99% of the
materials ap?lied by extrusion. These materials are not
used in a true magnet wire application, i.e. an
electrical winding, the turns of which are insulated to
provide low voltage, mechanical, and thermal protection
bet~een turns, and do not possess m,agnet wire
properties. In contrast, these materials are
conventionally used in lead wire or hooX-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.
~hile 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 operation, still, a conventional extrusion
apparatus is not without problems. Conventional
extruders include a centezing 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
12~L~4Z~ ,
~. ,
filament. The pri~ary problem ~ssociâted with extrusion
apparatus is the .~ear on t~e centering die. Since the
centering die used to cent:er the filament within the
sizing die, the centering die rnust be finely adjusted to
achieve a concentric coa~ing 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 tha~ occurs, diamond centering dies
have been consiaered, but not widely used.
Therefore it ~ould be highly desirable to ?rovice
an improved method and apparatus for T,an~facturing
mmagnet wire which -~ould have all vf 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 wire 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 O~ LHE 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 therefore eliminates the~need
for solvents, pollution control equipment or for
~ 94~:~ f
reclaiming solvents from the ~,anufact~ring process,
lowers the cost of ~T,anuf~cturing ~t leàst proportionally
to the cost of solvent, and conserves energy at least to
the degree that energy is required to remove solvents
from the irsulation 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 of ir.sulation material solutions or materials
reauiring c~ring after application.
It is another object of this invention to provide a
me.hod and apparatus for manufacturing ~agnet wire which
does not req~ire multiple coats to obtain the re~uired
concentricity and/or continuity.
It is another object of this invention to provide
an improved method and a?paratus for manufacturing
magnet wire in which a coating material can 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 by which magnet wire can be manufactured at
speeds which are limited only by filament pay-off and
take-~p 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 manufacturing
~21~
magnet wire which completely eliminates or substantially
reduces the use of solvents thereby eliminating the cost
of solvents and the need Eor pollution control equipment
or to reclaim the solvents from the manufacturing process.
It is another object of this invention to provide
an improved method and apparatus for manufacturing 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 is 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 extru-
sion process but none of the disadvantages.
In the broader aspects of the invention, there is
provided a magnet wire comprising: an elongated conductor
and an essentially concentric and continuous coating super-
imposed on said conductor, said coating being applied to
a desired thickness in a single pass, said coating being
applied in accordance with the following steps:
a. passing said conductor through a stationary
entrance dieat a speed in excess of 100 feet per minute,
b. passing said conductor through a stationary
exit die at a speed in excess of 100 feet per minute, said
exit die having a throat portion, an entranceopening
--8--
~2:19~0
larger than said throat portion interconnected by a
converging interior wall thereby defining a die cavity
between said throat portion and said opening and said
conductor and said wall, said entrance die and exit die
defining and partially enclosing a die chamber there-
between, said conductor in said dies being spaced from
said dies,
c. 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 chamber above atmospheric pressure,
e. passing said conductor 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 excess of said material from said
conductor leaving an essentially concentric coat of said
material on said conductor of a thickness meeting the
requirements of ANSI/NEM~ Standards Publication No.
MW1000-1977.
BRIEF DESCRIPTION OF THE DRAWINGS
The above mentioned and other features and objects
of this invention and the manner of attaining them will
become more apparent and the invention itself will be
19~ f
bes~ ~nderstood by reference to the fellowiny
description of the invention ~aken in conjunction with
the accompanying drawinss 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 Fig. 1;
Fig. 3 is a front ?lan view of the coating die of
the invention taken substantially along the Section Line
3-3 of Fig. l; and
Fig. 4 is a cross-sectional vi2w of Lhe coating die
of the invention taXen substantially along the Section
Line 4-4 of Fig. 2.
DESCRIPTION OF A SPECIFIC Ei~BODIMENT
.
~PPARATUS
Referring to the drawings, and specifically Fig. 1,
the apparatus of the invention will be described. The
apparatus 10 generally consists of a filament pay-out
device 12, a filament heater 14, a coating material
dispenser 16, a coating die 18, a hardener 20, and a
filament take-up device 22. As shown in Fig. 1, the
filament 24 is broXen at 26, at 28, 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 inserted. 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
- 10 -
~219420
effects ~f drawing the wire or stretching t;~e ~ire T,ay
be eliminated. In ot~er s?ecific embo~iments in which
magnet wire is being "anufactured by the ap2aratus 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
~ilament in a continuous manner.
The term "filament" is used herein for all strand
ma.erials. Filaments thus include both copper and
aluminum conductors and insulated copper and aluminum
conductors which prior to the application of a coat of
material by the apparatus and method of the invention
have been lnsulated with a base coat of insulating
material~ a tape of insulating material ei-her spirally
or longitudinally wrapped on the conductor, or other
conventional insulating materials, and other strand
materials desirably coated. While the specific
embodiments herein described 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 "flowable material" is used herein for the
general class of coating ma.erials 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
seneral 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
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~LZ~9420 , f
hardened by curing or therrnosetting ~ne -aterial and
also coating materials whicn ;,ay i~c~uce 1~ a a~u~ 5
by weight of solvent to render ~hem ~~'owarl -nd l,ter
hardenable by driving the solvent from thP ma.erial. In
the manufacture of magnet wire, several different
materials can be applied by the method and a?pâratus of
the invention. These include but are not limited to
polyamides such as Nylon, pol~-ethylene terepnthalates,
polybutylene terephthalates, polyethyle,es,
poly?henylene sulfide, ?olycarbonates, ?ol~-prop~lenes,
polyethersulfone, ?olyether imiaes, polyet:r,er
etherketone, polysulphones, epoxvs, flurocarbor.s
including ethylene-chlorotrifluoroethylene and hylene
tetrafluoroethylene polyvinyi fo.m21, phenox~s,
polyvinyl butyrol, polyamide-imide, polyesters and
com~inations 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. 02eratively associated with the spool 32 is a
brake 38 which restrains the rotation of the spool 32 as
the filament 24 is being pulled therefrom by the take-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 com?letely 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
bare copper and aluminum conductors are now transported
from the rolling and drawing operations to the magnet
- 12 -
0 f
wire manufacturing alants. In all ins~r~ceJ wriere ~ho
t~xe-up device 12 is elimir.at~d and rolling ~nd dr_~ing
?erations are substit~ted therefore, an anneâler 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
aP?aratUS OL the invention to be used in the perfGr~ance
o- the method of the invention. A filament hea.er may
be used solely to raise the tem?erature of the filament
?rir to the a??lication of the coating material or may
be an annealer if har~d bare wire is used or to further
reduce the effects of the aforementioned rolling and
d-awing process, if required. Thus, in a specific
embodiment, the filament heater 14 may consist of an
annealer, or may consist of a filament heater. In the
s?ecific filament heater embodiment 14 illustrated in
Fig. 1, the filament heater comprises a resistance coil
40 being generally tubular in shape and having opposite
0~2n ends 42 and 44. The filament or conductor 24 is
trai..ed bet~een the pay-out device 12 and the take-up
device 22 through the coil 40. ~he filament heater 14
is also provided with a control 46 by which the
temperature of the conductor 24 can be controlled. The
filament heater 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 ccating die 18 is illustrated in Figs. 1
through 4. The coating die 18 incl~des 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
1219~20 f-
screws 66. ~xit die 62 is ,"~n' ed in t~e .-arhdrd
portion of die block 64 by screws 66'. ceDardting
entrance die 61 and exit die 62 is an interior ?assage
65. Die block 54 is provided with heater bores 68 in
which heaters 70 are positioned. In a specific
embodiment, each heater 70 may be a tubular ca1rod
heater. Additionally, the die block 64 is provided with
a thermocouple bore 72 therein in which a thermocouple
74 ~shown only in Eig. 4) may be positioned.
F~rthermore, die block 64 is provi2ed ~ith a nozzle bore
75 therein to which the nozzle 54 of material applicator
16 is connected. Hereinafter, die temperatures are
reported witn regard to specific examples; these die
temperatures are measured by thermocoupie 74. Heaters
70 are connected by suitable conductors to a heater 76.
~eater 76 is provided with paired controls 78 whereby
the temperature of the entrance die 61 and the exit die
62 each can be elevated above ambient te.~~erature ~for
each die) and controlled, respectiveiy, as desired.
Referring to ~ig. 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 op2ning 86 and a diveraing interior wall 88
interconnecting the throat 82 and the exit op~ning 86.
In a specific embodi~ent, the entrance die 61 can be
constructed as illustrated in a two-piece fashion having
a central piece 90 including a throat portion of harder
and more wear-resistant material, and ex,erior piece 90'
which includes both the e-ntrance opening 80 and the exit
opening 86.
- 14 -
1,~ 2~:) f-
The exit die 62 is -l~o s~own in cross-~ection to
include an entrance o??ninq q2, a throat 93 and a
converging interior wall 9~ whicn interconnects the
throat 93 and the entrance opening 92 of the exit die
62. Converging interior wall 94 partially defines a die
chamber 95 as will be mentioned hereinaf~er. Exit die
62 also has an exit opening 96 and a diverging interior
wall 97 that interconnects the throat 93 and the e~it
opening 96. In a specific ~mbo2iment, the exit die 62
can be constructed as illustrated in a two~?iece fashion
having a central piece 98 including a Lhroat portion or
harder and more wear resistant ma,erial than the
exterior piece 98' which includes both the entrance
opening 92 -nd exit opening 96.
In a speciric embodim?nt, 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 ~alls 84 and 94 to diverging wall ~8 and 97
so as to define an angle with the conductor 24 of about
1 to about 2 degrees.
The flowable 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 flcwable
material through a nozzle 54. ~hen 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 naterial 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
121~34ZO
a?plicator 16 ;nay ~e an extrusion ap?aratus havir.g the
'eatures above .'escri~ed. ~n t.,o~e ~p?lic2tiGns in
which the flo~able .material is rendered more .lowable i~y
the use of a small portion of sollJent, both the coating
material and the solvent mav be fed into the applicator
via the chute 48 and the reservoir 50 may be ?rovided
with a mixing apparatus having associated therewith a
separate control Ç0~ .
The central die cr.amber 95 is co;nple'elv detined by
the diverging W311 88 of entrance die 61, the converging
interior wall 94 o- exlt die 62, and the walls OL
interior passaae 65 of die block 54, Die chamber 95 is
?ositioned between ~hroat 82 and throat 93. The nozzle
54 is connected to no~zle 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 'ake-up device 22
through the entrance 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 ccated filament or maanet wire by the
take-up device 22. The hardener 20 as illustrated
inc'udes 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 trouqh 100, and exit the open end 104.
Also as shown, the trough 100 is slGped downwardly
toward the open end 102 and provided with a source of
cooling fluid, such as water 108, adjacent open end 104
and a drain 110 adjacent open end 102. In many specific
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~Z1~20
~ "
embodiments, a water quench utilizing ti1e structure of the hard-
ener 20 is desired. In other specific embodiments, a quench is
not required and thus, the cooling fluid is not used. In these
embodiments, either a ~low of ambient air or refrigerated air
(where available) is trained on the coated conductor or filament
24.
In specific embodiments in which multiple coats of dif-
ferent materials are being applied to the filament or conductor 24
by successive spaced apart coating dies 18, the particular coating
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 coating 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-
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-
ment. Thus, reels 32 may be the conventional spools on which
coated filaments are conventionally shipped. Spools 32 are mount-
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.
THE :I_THOD
The method of the invention will r,ow be described.
~eference to Figs. 1 through 4 will be ref-rr2d to and
the terms "flowable material" 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 p25S whereby the
filament or conductor is drawn or otherwise formed,
coated and s ooled 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 drawin~
operation. If sup?lied from a rolling and drawing
operation, the conductor 24 is alw~ys 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 rilament 24 is heated 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
material. 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
slightly above the ambient temperature.
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~ L9~0
The central die ch~mber 99 is then filled with a
flowable ~iaterial, The flowable "ateriàl is stored in
the material reservoir 50 at a flowable te.~?erature and
pressure and is injected into the central die cnamber 99
by ap?licator 16. Once the central die chamber 99 has
been filled with material, the flowable material
contained therein will assume the pressure of the
flowable coating material in the reservoir 5C. Pump 52
must have an adequate capacit~ to ,main~ain pressures up
to about 2000 psi in reservoir 50 and cr.amber 99. 3y
control 58, the res?onsiveness to pressure changes
desired can be controlied. By controls 56 and 78, the
tel!perature of the material in the reservoir 50 and
c;.amber 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 rlowable material in the central die chamber 99 is
too great, the flowable coating material .-nay 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 will leak from opening 80 when the filament is
stationary in openihg 80. Any significant leakage of
flowable coating macerial 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 t;~e flowable material perforrns its centering function
relative to the exit die 62 and produces a concentric
-- 19 --
~2~947~0
coating as will be subse~ently discus~sed, wets the
Cil~ment ~o be coated, ~nd suitably adheres to t~e
filament. Thirdly, if the pressure and the tem?erature
of the flowable material is too low, excessive filament
stretching may occur rrom die 18 excessively resisting
the movement of filament therethrough. It is for these
reasons, that the applicator 16 is provided ~ith
controls 56, 58, and 60.
The coating material is then applied to the
filament or conductor 24 by passing the same through die
18. The coating mat2rial within the die chamber
runctions to center the filament or conductor 24 ~ithin
he throat portions 82 and 93 of dies 51 and 62. In all
ins,ances known to the applicants whereln the central
die chamber 99 is properly filled with coating material
115 and the temperature and pressure therein are
properly controlled, filaments or cond~lctors 24 that are
coated by the method and apparatus of the invention have
a surprisingly concentric and continuous coat of coating
material thereon. Conversely, in all situations in
which the central die cha~ber 99 is not properly filled,
and/or the tempera.ure 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 .-ontrol of the
temperature and pressure of the coating material therein
are essential to the method of the invention. Coating
materials of various types have been successfully
applied in accordance with the method of the invention
by the above-described ap?aratus at viscosities from
about 5,000 cps to 200,000 cps.
Applicant does not completely understand the
actions of the flowable material within the central die
- 20 -
chamber 99 which results in filaments having coatings of per-
fect concentricity and continuity thereon. The coating
material contained within the central die chamber 99 is believed
to have movement adjacent the throat 83 of the exit die 62.
This movement may be somewhat similar to the movement of the
annular or toroidal support 120 as described in United States
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
filament 24.
The throat portion 93 of the exit die 62 regulates the
thickness of the coat of coating material left on the filament
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 thickness of the coat of coating material to
be applied thereon. The method of the invention has been sucess-
fully 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 portions
82 and 93 of the entrance die 61 and exit die 62, respectively,
can be provided in a geometrically similar shape. Coatings
from about 1/2 mil to about 16 mils thick can be applied by the
method of the invention. Depending upon the flow properties of
the coating material, the throat portion 93 of the exit die
- 21 -
~ 94;2C) f
62 wil~ have a dia,ieter in most c_ses from a~out the
desired diameter to about 2 mils laraer ~han thP desired
diameter of the ccated 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. ~hile 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 ~uench or an air
quench may be utilized. Additionally, in those flowable
ma'erials in which sma~l amounts of solvent are used to
aid in the properties of the flowabl2 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 utili~ed 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 o?eration and function o' the take-up device 22
was described hereinabove. ~owever, the speed at which
the take-up device 22 was driven W25 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 ccating materials mentioned herein. '~'hen the
pai~-out device 12 is eliminated and conventional rolling
and drawing operations are substituted therefore, the
speed at ~hich the take-up device 22 is driven by the
- 22 -
~ ~L2194~:0 f
driver l14 is solely li~ited bv the '_Xe-up device 22,
itself.
Specific e.Yamples in wnich conductors of ~arious
sizes have been coated with coating ..,aterial such as
above mentioned in accordance ~ith the method of this
invention are tabulated in Table 1. Table l 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
el-ctrical ?roperties of thè ,magnet -~ire produced in
this specific ex mple in accordance with the method of
the in~ention utiliz ng the apparatus described
h~reinabove.
~ he magnet wire produced by the apparatus of the
in~ention in accordance with the method of the invention
meets all of the re~uirements of magnet wire made by
other existing commercial processes. Table l ta~ulates
the physical and electrical properties of various magnet
wires manufactured in accGrdance with the method of the
inJention utilizing the a??aratus of the in~-ention. A
surprising characteristic of all magnet wires made in
accordance with the method of the in-~ention utilizing
the a??aratus of the in~entiGn is the cGncer,tricity or
the coating .~?plied to the conductor and the continuity
thereof. ~oth 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 fil~ment 24 is
centered within the coating die 18. .~agnet wire
produced by other commercial processes, such as the
- 23 -
~2~L13~
application of coatings from solution, periodically result in
non-concentric coatings and non-continuous coatings. In fact,
the continuity of coatings applied from solution is such that
reliance upon a single coating of magnet wire insulation is un-
heard 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, concentrically, 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
disclosed in United States Patent No. 4,393,809 above mentioned.
The speed is limited only by the pay-off and take-up devices.
The conductor can be drawn or otherwise formed, coated, and
spooled in a continuous operation which completely eliminates
or substantially reduces the use of solvents, thereby eliminat-
ing 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 apparatus of the invention has all of the advantages of
- 24 -
9~
a conventional extrusion process but nore 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.
- 25 -
3L;;~19~20
26
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