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Патент USA US2562257

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July 31, 1951
Filed Jan. 21, 1948
2 Sheets-Sheet l
Orrm E. Andrus
July 31, 1951
2 Sheets-Sheet 2
Filed Jan. 21. 1948
‘.7 .
A.“ .
Orr-m E. Andrus
W40. 46%“
Patented July 31, 1951
’ Orrin E. Andrus, Altadena, CaliL, assignor to A. 0.
Smith Corporation, Milwaukee, Wis., a corpo
ration of New York
Application January 21, 1948, Serial No. 3,384
2 Claims. (Cl. 171-252)
This invention relates to an electromagnetic
device such as a motor stator and the method
of making same.
The steel, copper, varnish, paper and slot
sticks in electromagnetic apparatus, such as a
motor stator have different thermal coef?cients
of expansion. In large motors, in particular,
the differences in expansion of the various parts
is appreciable and the copper coils tend to move
with respect to the core. The insulation under
these conditions is likely to crack and separate
causing electrical breakdown and failure.
One object of the invention is to remedy the
slots 3 are lined with a suitable insulating ma
terial 5, such as paper or the like.
The windings may be assembled in slots 3 in
a number of different ways.
They may, for
example, be preformed and inserted in the slots
as a unit or the individual conductors may be
progressively introduced into the slots. Ordi
narily the parting strip 6 is provided in each
slot to lessen the voltage differences between
the conductors of the windings.
The insulating material 5 is preferably lapped
at the mouth of each slot 3 to enclose windings
4 within the slots and slot stick ‘I of soft non
described ‘condition by providing a stator or other
magnetic metal or synthetic material is located
electromagnetic apparatus in which the lami 15 in the longitudinal groove 8 adjacent the mouth
nations are twisted or offset and the windings
bound thereto and to each other so that the
of each slot 3 to close the slot and hold the
windings in place.
laminations and windings move as a unit.
The laminations 2 of stator l are twisted or
Another object is to provide a stator in which
offset axially with respect to each other and
the laminations are twisted and held in a crimped 20 the windings 4 are bound within, the lamina
state by welding.
tions in the twisting operation, as will be de
Another object is to provide a method of
scribed more fully hereinafter.
constructing a twisted motor winding to prevent
The laminations 2 are held in a twisted state
injury to insulation by differences in theexpan
by a plurality of welds 9 which extend the length
sion and contraction of the parts.
25 of the stator. Mechanical means, however, may
Another object is to provide a stator in which
also be employed to hold the laminations after
the laminations and windings are bound together
twisting is accomplished.
in such a manner that there is no great move~
In carrying out the invention the laminations
ment of one with respect to the other in a single
2 are ?rst stacked together with slots 3 in longi
area which would produce failure of insulation. 30 tudinal alignment. Thereafter the slots are
A further object is to bind the windings with
lined with insulating material 5 and the windings
in the laminations to prevent injury to the
4 are inserted with the parting strip 8 being dis
windings by chaf?ng from vibration.
posed midway of each slot to separate the con
Other objects and advantages of the inven
ductors. The insulating material 5 is then
tion will appear hereinafter in connection with 35 lapped at the mouth of the slot and each slot
the following description of several embodiments
stick 1 is slipped into its respective groove 8.
of the invention illustrated in the accompanying
The twisting of the stator can be accomplished
drawing in which:
in a number of different ways and the twist or
Figure l is a perspective view of a stator be
offset of the laminations 2 may take several
fore twisting;
40 forms. Thus the stator may be twisted along
Fig. 2 is a fragmentary transverse section
the entire length or the slots merely arched in a
through the stator with windings assembled
single arc. Figs. 5 and 6 show a slot of the stator
therein and ready for twisting;
after twisting and illustrate several embodiments
Fig. 3 is a sectional view of a stator con?ned
of the invention.
in clamping dies preparatory to twisting the 45
Fig. 4 is a view showing the method of weld
ing the stator after twisting;
Fig. 5 is a perspective view showing a stator
after twisting;
and .
Fig. 6 is a view similar to Fig. 5 showing the
stator twisted in another manner.
The invention is illustrated by the stator I
formed of a plurality of stacked laminations 2
having slots 3 to receive the windings 4. The 55
Fig. 3 illustrates apparatus for twisting lami
nations 2. In carrying out the twisting opera
tion, after assembly of the windings 4 and lami
nations 2 of the stator I, the mandrel I0 is in
serted through the air gap of the stator and nuts
I I are threaded onto the ends of the mandrel and
against spacer members engaging the outermost
laminations 2. The nuts ll, however, are not
initially tightened in place.
The entire assembly is then placed in a ?xture
comprising split clamps I2 at each end and which
are supported on a base member II. ‘The split
clam'p I4 is assembled around the center of the
stator I. The clamp II is rotatable and is ro
tated by handle IS. The clamps I2 and clamp
I4 are secured around the stator by suitable bolts.
When handle I! of center clamp I4 is grasped
and pushed or pulled by the operator the clamps
I2 securely hold the stator at either end and the
laminations 2 are twisted or o?'set as desired.
The o?set or twisting of the laminations to
bind or pinch the windings 4 within intimate
contact with themselves and with the lamina
tions 2 should be su?icient to force the windings
throughout the length of the entire stator insure
that there will be no separate movement with re- ‘
spect to the laminations and the windings.
The insulating material 5 separating windings
I from laminations 2 prevents damage to the
windings when the latter are bound tightly with
in the laminations. The material 5 also stretches
to some extent in service to take up minor dif
terences in expansibility between the iron lami
nations 2 and copper windings 4.
Where the twisted stator is‘ employed it is un
necessary to twist the rotor bars of the rotor with
which the stator is used. Inaddition the winding
4 and laminations 2 to expand and contract as a
coils are assembled more readily since the mouth
15 or the slots may be initially wider for assembling
After twisting the laminations 2, as described,
the coils as the twisting of the core narrows the
the nuts II are tightened securely against the
mouth of the slots in the ?nal core.
spacers engaging the laminations, the stator I is
then removed from the clamps I2 and clamp ll
of the twisting ?xture, and the laminations 2 are
permanently joined together in the twisted state
by longitudinal electric arc welds Q or other
Various embodiments of the invention may be
employed within the scope of the accompanying
I claim:
1. A twisted laminated core having the corre
sponding slots of the laminations thereof oiiset
It is preferable. however, to join the lamina
from each other, motor windings disposed in said
tions together by} welds 8. In carrying out the 25 slots before oilset thereof and bound within said
welding operation it is necessary to prevent the
core by o?set oi! the laminations to e?ect sub
welding heat from penetrating to windings I and
stantially unitary movement of the laminations
suitable means.
injuring the same.
of the core and the windings under thermal ex
The stator I, still retained in a twisted condi
pansion and contraction in service, and a longi
tion upon mandrel II by nuts II, after removal
tudinally extending member separate from said
from the twisting dies, is placed in tank I6, on V
windings and securing said laminations in offset
shaped support I'I. Tank I6 is filled with water
up to a line where only the upper longitudinal
2. A twisted laminated core having longitudi
portion of the laminations I of the stator I are
35 nal slots extending through the laminations of
the core with the corresponding slots of indi
The welds 9 are then made by depositing weld
vidual laminations oifset circumferentially in
metal along the length of the laminations by a
the core, motor windings disposed in said slots
welding rod I8 which is connected to a welding
before offset thereof and bound in intimate con
generator, not shown, through cable I8. Fig. 4
illustrates how one of the longitudinal welds 8 is 40 tact with said laminations and with each other
by offset of the laminations to provide for sub
made. When one weld is made, the stator I is
rotated to another position by the operator and
another weld 9 is then made along the longi
tudinally exposed portionv oi.‘ the stator. The
water in tank I6 carries away the heat of the 45
arc and prevents the windings from being
stantially unitary movement of the laminations
and windings under thermal expansion and con
traction in service, and an interlock between said
laminations to secure the same in o?set relation.
After the welding is completed the stator I is
lifted from the tank I8, the nuts II are un
threaded and the stator is removed from man
drel II).
The following references are of record in the
?le of this patent:
The stator may be completed by being dried,
impregnated with varnish and baked.
Under the invention, the laminations and
Martin __________ __ Aug. 17, 1915
windings expand and contract substantially as a 55 2,012,021
Petersen ________ __ Aug. 20, 1935
unit and there is no tendency of the windings to
Elsey _____________ __ July 8, 1941
slide in and out of slots 3 in service. Strain on
the varnish insulation is held at a minimum and
breaking thereof which would ordinarily occur if
the windings were free to move away from and 60
through the laminations is prevented. The
tightness and the crookedness of the windings
Rancher __________ __ Oct. 2, 1945
Dolan ____________ __ Sept. 7, 1948
Switzerland ______ _- May 1, 1934
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