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Патент USA US3047769

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July 31, 1962
3,047,756
A. D. COGGESHALL
GLASS-RESIN TAPE FOR ARMATURE BANDING
Filed Jan. 2, 1959
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United States Patent 0 “ice
3,047,756
Patented July 31, 1962
2
3,047,756
Almy D. Coggeshall, Schenectady, N.Y., assignor to Gen
GLASS-RESIN TAPE FOR. ARMATURE BANDING
eral Electric Company, a corporation of New York
Filed Jan. 2., 1959, Ser. No. 784,744
6 Claims. (Cl. 310-271)
The invention described herein relates to glass ?ber
Such a construction would permit winding the roving
over sheaves, tension devices, and other objects having
sharp bends and where it is desired to maintain them
under relatively high tensions or pressures.
The primary object of my invention therefore is to pro
vide such an improved resin impregnated glass roving or
banding tape incorporating the desirable features of high
tensile strength and ?exibility.
Another object of my invention is to provide resin im—
banding and more particularly to resin impregnated glass
pregnated glass banding material having a lesser amount
ribbon or tape of high tensile strength used for restraining
end turns of dynamoelectric machines against radial dis 10 of resin than that taught by the prior art for furnishing
placement.
a high degree of elongation at a high stress level so that
when the material is applied to coil end turns, the force
resulting from such elongation, which remains permanent
roving comprising parallel glass strands impregnated with 15 with time, resists the greatest outward force presented
by end turns.
a thermosetting resinous composition which when cured,
The Coggeshall et al. Patent 2,747,118, assigned to the
same assignee as the present invention, discloses glass
displays great strength and rigidity and important electri
cal characteristics making it especially adaptable for use
in dynamoelectric machines. The roving or glass band
ing is applied circumferentially on the outer peripheral
surfaces of rotor end turns to exert an inward radially
directed compressive force which is greater and opposite
to the outward forces produced by centrifugal action. If
the inward compressive force is lost or decays, the end
In carrying out my invention, I provide improved glass
banding tape consisting of substantially parallel glass ?
bers, woven or otherwise formed, and impregnated with
between 2% and 8% resin by weight. Upon complete
curing of the resin, the tape displays exceptional tensile
strength and ?exibility heretofore considered incompatible
in the same product. The degree of impregnation of the
resin is such that the interior of the individual ends com
turns then can be thrown centrifugally outward to cause 25 prising the tape is well bonded while the bonding between
ends is weak, thus imparting flexible characteristics to
the tape and permitting it to be wound over tension de
vices having reverse bends and other objects of irregular
insulation or of the coil conductors themselves may occur.
or smooth con?guration. Any load to which the tape
The resin in the roving is in the form of a highly viscous
solid when the roving is applied to either stator or rotor 30 may be subjected is shared equally between the parallel
glass ?bers thus greatly increasing the tensile strength of
coil end turn surfaces. A ?nal cure under the influence
the composite of ?bers and permitting the tape to be
of heat imparts the desired strength properties to the mate—
rial for preventing subsequent movement of the end turns
wound at stress levels in excess of 100,000 p.s.i. When
the material is wound peripherally in the form of a ring
when acted on by magnetic and/or centrifugal forces.
unbalance of the rotating member. Moreover, in the
event gross displacement takes place, rupture of the coil
Operation of dynamoelectric machines having such roving surrounding the end turns has proved successful.
The commercially available glass roving used for this
purpose consists of a multiplicity of mono?laments, usu
on the end turns of a dynamoelectric machine, the ring
displays a greater and more permanent degree of tensile
elongation than prior rovings and the elastic elongation
acts to produce a radial inward force on the windings
of the machine which opposes the outward centrifugal
ally 204 mono?laments, of extremely small cross section
loosely gathered to form an end. A plurality of such 4:0 forces and holds the end turns substantially immovable.
While the speci?cation concludes with claims particu
ends constitutes the roving. These mono?laments or ?bers
which initially are not treated with a resin, are free to
larly pointing out and distinctly claiming the subject mat
ter which I regard as my invention, it is believed the in
move laterally with respect to each other, thus giving the
vention will be better understood from the following de
roving the attribute of ?exibility. If the roving is then
placed in tension, there is little sharing of the load between 45 scription taken in connection with the accompanying draw
ing in which:
?bers so that the structure fails ?ber by ?ber and the
entire bundle is seen to rupture at a low value of elon
FIGURE 1 is a view in elevation of a form wound rotor
illustrating the application of the roving to the coil end
gation, approximately 1%; of 1%, with a corresponding
turns:
tensile stress of about 20,000 p.s.i. However, when the
roving is impregnated with a ‘resin of the type disclosed 50 FIGURE 2 shows a similar application of the roving
I
W
in the Coggeshall et al. patent, to produce a limp, tack
free ?exible product, the resinous binder provides a cer
tain amount of sharing between ?bers so that both the
to the end turns of a random wound motor; and
strength and elongation is approximately doubled.
ceptionally high pressures.
FIGURE 3 illustrates the use ‘of the roving when ap
plied to a container designed for holding ?uids under ex
The resinous binder in this state is an uncured plastic 55 As indicated in the introductory portions of the appli
solid and ‘will slowly flow under the ‘application of stress
cation, untreated roving comprising a multiplicity of glass
mono?laments or ?bers is not capable of withstanding
so that over a period of time, the tightest ?ber assumes
great axial strmses imposed thereon because the load is
the major load, and failure, ?ber by ?ber, again becomes
not capable of being shared equally between adjacent
possible. Curing of the resin will negative this disad
vantage ‘however. The prior art teaches that it is desir 60 ?bers. As a result, a tearing type of failure is obtained
wherein the ?bers break individually and sequentially
able to have approximately 20 percent of resin by weigh-t
in the ?nal composition in order to obtain bonding be
rather than having the whole mass of ?bers fail simultane
ously. When treated with the partially cured resinous
tween successive layers and to develop a unitary structure
composition referred to in the Coggeshall et al. patent,
during ?nal cure which provides maximum mechanical
strength. A concept also generally accepted was that if 65 the mutual adhesion ‘developed between ?bers, while of
less than 20% of resin was used, the material was said
to be “starved,” dry, de?cient in stiffness and mechanical
a low order, makes possible a stronger material.
While conducting experiments with roving having a
glass content from 68% to 95% glass, and the remainder
hardened resin, I unexpectedly found that with very light
It is evident that it would be ‘highly desirable to com
bine these distinct characteristics of ?exibility inherent 70 resin applications followed by complete curing, it is pos
sible to obtain very high tensile strengths and for the
in the untreated roving and improved tensile strength
roving structure to separate or internally delaminate with
resulting from partially curing the resin treated roving.
properties.
3,047,756
3
4
.
out affecting the main strength of the ?bers, thus giving
added ?exibility.
tially cured in the manner disclosed in the Coggeshall et
a1. patent to provide a semi-solid, tack-free resin. The
Using these very low resin values, the internal structure
resin in the glass ?ber bundles in (3) was fully cured
of the roving or tape delaminates rather readily and thus
prior to the test. The improvement in ultimate stress
the material becomes ?exible without greatly damaging C21 and elongation characteristics, as indicated in (3), over
prior rovings is impressive. It is especially signi?cant
the fundamental ?ber integrity. The use of low resin con
centrations also increases percentage-wise, the volume of
glass in the ?nal structure which increases the strength
in light of present extensive use of resin treated glass
?ber tapes in banding armature end turns. Constant ef
on a cross sectional area basis.
fort is being made by tape manufacturers and others to
This surprising observation constitutes a departure from 10 provide a product to the electrical industry which would
the prior art which has observed very high strengths in
exhibit these desirable characteristics and be capable of
unidirectional ?ber structures, but it has taught that opti
ful?lling the other necessary requirements when installed
mum strengths were found in the range of 70% to 80%
on dynamoelectric machines.
by weight of glass, with the remainder resin, and that
when the glass content exceeded 85% by weight, grossly
of resin in the banding tapes disclosed herein, is not
inferior strengths were obtained.
because this previouosly unknown product will satisfy
The use of lesser amounts
merely a matter of degree as one initially would expect
The tape may comprise substantially parallel glass ?bers
the need ‘for a banding tape that inherently will contain
all the tensile strength necessary for compressing the end
of the type conventionally found in the textile industry.
turns inwardly of even the largest dynamoelectric ma
In the latter type of rovings or tapes or yarns, it is desir 20 chines.
able to maintain the ?bers in substantial parallel relation
The effect of the present invention in retaining pre
ship with each other.
stress in the glass banding tape is illustrated in Table II.
More speci?cally, it Was discovered that by reducing
In these experiments, a drum was mounted in a winding
the resin content in substantially parallel glass ?bers, from
lathe, and instrumentation was provided to measure the
1/3 to 1/10 of that previously used, and by curing this resin 25 inward radial force produced by tension in the applied
to a hard strong solid that the elongation of the ?ber will
?ber. This testing structure measures the inward com
rise to approximately 2 percent with corresponding tensile
ponents of force accurately. A number of duplicate spe
stresses in the glass in the order of 200,000 p.s.i. The sig
cimens also were wound with various materials and sub
ni?cance of this value may be better understood in the
jected to heat in the same manner as that encountered by
light of the knowledge that the strength ‘for a single freshly
a rotor for a dynamoelectric machine during the manufac
turing operation.
drawn glass mono?lament under ideal conditions is given
as 450,000 p.s.i.
Table 11
The prior art has taught that the resin impregnated in
the glass ?brous material had to be cured partially to per
Stress in
or monolilaments assembled together to form a product
mit factory handling of the product. Final curing of the
35
Stress in
resin then was obtained after the material was applied to
?ber after
heating 24
Fiber during hrs. at 150° 0.
winding
the product and heated. In the event the glass ?bers were
bonded together by fully curing the resin, stiff rod-like
and cooling
to room
temperature
structures were obtained which were totally unsuitable
for being wound on spools, ‘accepting reverse bends in ten
sioning devices, and other uses to which such materials
would be subjected. Because of its uniquely low resin
content, the glass ?brous material described herein can
be cured before application to a product, and while not
limp, is of adequate ?exibility for the intended applica
(1) Bundles of glass ?bers impregnated
with a liquid resin at the time of
winding ___________________________ __
20, 000
2, 000
50, 000
16, 000
(2) Bundles of glass ?bers treated with
>
approximately 20% resin ___________ __
(3) Bundles of glass ?bers having a 20%
resin content but heated at the time
of winding to soften resin so that ma
jority of the resin ?ow would be pro
duced by the action of the tension
tion. When sharply bent, the material does not crack as
device _____________________________ __
50, 000
37, 500
would be expected, but rather, delaminates in a local area
(4) Bundles of glass ?ber treated in ac
so that the ends comprising a multiplicity of glass ?bers
cordance with the present invention,
lightly coated with the same resin as
become separated over only a short distance. When
in (1) at the time of winding _______ ._
102,000
98,000
placed in tension, these ?bers align themselves to substan 50
tially the same ‘orientation as before delamination, so that
From the above table it is seen that glass banding tape
the tensile strength and elongation of the material are
prepared in accordance with the present invention may
substantially unimpaired.
be applied with a stress approximately twice that of the
To illustrate more clearly the improvement in ten
prior
art, and that the usefully retained stress is almost
sile strength and elongation obtained by the practice of
the present invention, Table I shows these values for un
treated glass specimens, for glass ?bers impregnated with
approximately 20% resin, and ‘as according to the present
invention.
Table I
stress, p.s.i.
115221555;
based on total 9 6% nt '
cross section
20,000
p
08
. 19
(2) Bundles of glass ?bers treated with
approximately 20% rosin ___________ __
85, 000
1. 2
195,000
2.2
(3) Bundles of glass ?bers treated in ac
cordance with the present invention,
7% resin c0ntent,and cured ______ __ 1
One requirement for a material used ‘for binding the
end turns of dynamoelectric machines is that it may be
stretched or elongated to the maximum possible extent
and be capable of being bound peripherally around the
60 machine end turns in the stretched or elongated state.
Ultimate
(1) Bundles of untreated glass ?bers _____ __
three times that previously attainable.
This stretch or elongation shall be elastically recoverable
while providing the inward radial forces mentioned above.
It is obvious that if the stretching or elongation is in any
way diminished, the radial inward force will likewise di
65 minish with the undesirable consequences to the machine
previously discussed. The methods of manufacturing
electrical machinery impose conditions where a certain
vamount'of this elongation will be consumed in properly
70 seating coils, ‘compressing high spots and in a certain
amount of plastic deformation common to almost all in
sulating materials. Fortunately, all of the above are
reasonably constant. If the elongation imposed in the
of the type previously described. Those ?bers impreg
banding is small, almost all of it will be used up in seat
nated with approximately 20% resin as in (2), were par 75 ing coils, plastic flow, etc. and very little will be left
The bundles of glass ?bers used in (1) consisted of a
multiplicity of mono?laments joined together to form ends
3,047,756
5
to produce this inward radial force that is essential to
successful operation.
The requirements for the resin used in impregnating the
substantially parallel glass ?bers is that it should be capable
of bonding to the glass ?bers, and where a second resin is
used for sealing the free end of the tape, both resins should
be compatible with each other for obtaining the desired
unitary bonded structure. It should be capable of permit
ting internal delamination after the resin is fully cured.
Primarily, the resin should be resistant to the temperatures 10
and environments encountered by dynamoelectric ma
6
loose end as more fully described hereinafter. When sub
jected to heat, this additional resin cures to a hard mass
which ?rmly bonds the loose end to the adjacent areas of
the roving.
As indicated in FIGURE 2, the banding tape 20 likewise
can be applied as a shroud to random wound rotors of the
type comprising a rotor 22 having coils 24 disposed in the
rotor slots. A ?ange 26 may be used beneath the end
turns. Also, it will be evident that this banding tape can be
applied to coils of other electrical apparatus in which the
coil end turns move as a result of magnetic and/or cen
trifugal forces. An example of this is the coils positioned
in the stators for dynamoelectric machines.
fumes from chemical plants, carbon black and the like.
Since the resin in the tape is completely cured before the
A number of commercially available resins heretofore
used in impregnating glass ?bers were used successfully in 15 tape is applied to the end turns, it is evident that means
must be provided for securing the loose ends to form a
the developmental work connected with this invention.
unitary bonded structure. This may be accomplished by
Speci?cally, Laminac 4119 marketed by the American
adding a small amount of uncured resin in the form of an
Cyanamid Co., BRS-S 142 by the Bakelite Corp, #73517
overcoat to the tape at the time of manufacture, by apply
Resin and #3405 Perma?l resin by the General Electric
Company, all are satisfactory for use in the banding tape. 20 ing it directly to the ?ber at the time of winding, or only
to the loose ends of the tape. Preferably, it should pro
All of the above are modi?cations of a generic type of
vide a high degree of bonding to the glass ?ber structure.
resinous material known as unsaturated polyester resins
chines, such as, atmospheres containing oil, moisture,
Obviously, other means may be used, such as employing
which are dissolved in the reactive diluent such as styrene
metal tying clips to the free tape ends, or cinching them
or diallyl phthalate and are caused to solidify through the
action of a peroxide catalyst.
25 to the layers Wound therebeneath.
Another use for the tape involves its application to the
It will be obvious to those skilled in the reinforced plas
external surfaces of containers adapted for containing
tics art that many other resinous materials which are
relatively high pressures. As shown in FIGURE 3, a.
used successfully in connection with glass ?bers will be
cylinder of the type normally used for containing gas or
similarly applicable in the practice of the present inven
tion. Examples of the foregoing are resins of the epoxy 30 liquids under high pressure is often not capable of with
standing such pressures unless the walls thereof are of
or ethoxylene types, resins of the phenolic type, resins
heavy material. Since the banding tape can be applied
of the polycarbonate type and modi?cations or combina
thereto under tension, a predetermined amount of mech
tions of the above. In view of the above, it will be evident
anical energy can be incorporated in the structure by the
that any resin may be used with the tape so long as it meets
the requirements stated herein. Obviously, this improved 35 tape for augmenting the strength normally contained in
the walls of the container and eifectively serves the func
tape is not limited to use with dynamoelectric machines
tion of restraining the container against outward pressures.
since it is susceptible to general applicatons and has a
In view of the above, it will be evident that many modi
wide variety of uses. The foregoing examples are given
?cations and variations are possible in light of the above
by way of illustration and not by way of limitation.
Applications of the use of this banding tape for com 40 teachings. It therefore is to be understood that within the
scope of the appended claims, the invention may be
mercial and industrial uses are manifold. For example,
practiced otherwise than as speci?cally described.
the end turns of dynamoelectric machines such as the form
What I claim as new and desire to ‘secure by Letters
wound bars shown in FIGURE 1 or on the random wound
Patent of the United States is:
coils of FIGURE 2 can be drawn inwardly to a greater
l. A magnetic core for a dynamoelectric machine com
degree and a corresponding greater amount of mechanical 4:5
prising a plurality of laminations having coils therein, coil
energy imposed therein. Since the levels of stress are
end turns projecting outwardly from the core, and a
almost doubled over that previously obtainable, the inner
?anges and other devices used for supporting the end
plurality of substantially parallel glass ?laments impreg
nated with between 2% and 10% by weight of a resinous
of primary importance is that with the application of great 50 composition on said end turns for preventing displace
ment thereof when subjected to magnetic and/or cen
er hoop stresses, a lesser amount of tape is needed for
trifugal forces.
binding the end turns which in turn involves a smaller per
2. Glass tape for restraining end turn displacement in a
centage of time needed in binding the end turns in posi
dynamoelectric machine comprising a multiplicity of sub
tion. Therefore, not only does the tape display greater
tensile strength, elongation and increased ?exibility char 55 stantially parallel glass ?bers impregnated with a fully
cured thermosetting resinous composition in an amount
acteristics, but it also permits the manufacture of products
constituting between 2% and 10% of the total weight of
at lesser cost by virtue of the smaller amount of tape
the tape, said tape displaying properties of tensile strength
needed to perform the same function as that heretofore
in excess of 100,000 psi. and of sufficient ?exibility
used.
Referring more speci?cally to FIGURE 1, there is 60 to withstand reverse bends without structurally failing.
turns can be eliminated in some instances. An advantage
shown a stator 10 comprising a plurality of laminations 12
having coils including end turns 14 positioned in slots in
the stator in the usual manner. A rotor 16 mounted on a
3. A magnetic core for a dynamoelectric machine com
prising a plurality of ‘laminations having coils therein,
coil end turns projecting outwardly from the core, sub
stantially parallel glass ?bers impregnated with a resinous
shaft 18 is centrally positioned in the stator for rotation
therein. Resin impregnated glass banding tape 20 com 65 composition cured to its optimum level and wound on the
prising a plurality of substantially parallel glass ?bers
impregnated with between 2% and 8% resin of the type
described above, is wound in the form of a shroud on the
outer peripheral portions of the end turns 14. The resin in
the roving 20 is completely cured thereby permitting the 70
roving to be applied to the end turns with a force cor
responding with the tensile stress of 100,000 p.s.i. in the
peripheral portions of the end turns, said impregnated
glass ?bers displaying properties of mutual adhesion pro~
vided by the cured resin and thereby permitting the in
dividual ?bers to share the imposed load equally.
4. A magnetic core for a dynamoelectric machine com
prising a plurality of laminations having coils therein,
coil end turns projecting outwardly from the core, sub
stantially parallel glass ?bers impregnated with a resinous
roving. After the roving is wound on the end turns, the
composition cured to its optimum level and wound on
loose end may be secured to the layers. of roving there
beneath by merely applying a thermosetting resin over the 75 the peripheral portions of the end turns such that during
3,047,756
'2’
8
the winding process, the impregnated glass ?bers are elon
verse bends without structurally failing, and means on
gated .75 % or greater to impart an inward compressive
force substantially greater than any outward forces ex
pected to be exerted by the end turns.
5. The combination according to claim 4 wherein dur CT!
said tape for bonding the free end thereof to the layers
therebeneath, said means on the tape comprises a partially
cured thermosetting resinous composition in an amount
just su?‘icient to bond the turns thereof to each other
when subjected to heat.
ing the banding operation, the glass ?bers are elongated
greater than 1%.
6. A magnetic core for a dynamoelectric machine com
prising a plurality of laminations having coils therein, coil
end turns projecting outwardly from the core, and a 10
tape comprising a plurality of substantially parallel glass
?bers impregnated with a thermosetting resinous com
position fully cured under the in?uence of heat, said
References Cited in the ?le of this patent
UNITED STATES PATENTS
2,747,118
2,749,460
Coggeshall et a1. ______ __ May 22, 1956
Acton et a1. __________ __ June 5, 1956
OTHER REFERENCES
tape displaying properties of tensile strength in excess of
Railway Locomotives and Cars, December 1957, “Glass
100,000 p.s.i. and of su?icient ?exibility to withstand re 15 Tape for Armature Banding,” pp. 38, 39.
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