Method of and Apparatus for Insulating Electrical Conductors.
Year: 1895

page_text: Date of Application, 26th Feb., 1895-Accepted, 30th Mar., 1895
COMPLETE SPECIFICATION.
Method of and Apparatus for Insulating Electrical Conductors.
I, JAMES YATE JOHNSON of 47 Lincoln's Inn Fields, in the County of
London, Gentleman, do hereby declare the nature of this invention (which has
been communicated to me from abroad by Louis Welton Downes, of 484 Elmwood
Avenue, Providence, Rhode Island, United States of America) and in what
manner the same is to be performed to be particularly described and ascertained
in and by the following statement. :-
The present invention relates to a method of and apparatus for applying insulating
covering to electrical conductors and the like. The said method and apparatus are
specially designed for the production of an electrical conductor with an insulation
composed of asbestos, and the insulated conductor produced by the new method and
apparatus is included in the invention.
Heretofore asbestos insulation has been found defective and unsuitable for a great.
variety of uses in the electrical art because the nature of the substance is such that
it is extremely difficult to apply it to wire in a compact, uniform and sufficiently thin
coating, and in a permanent manner.
It has been proposed to apply asbestos covering to a tube by weaving or braiding
(as in a whip braiding machine) strands of asbestos fibre around a wire, but such
procedure has not been found successful in practice because the asbestos fibres are
short and brittle, and the covering is easily abraded, and detached from the wire in
handling and use.
The expense and bulkiness of conductors covered partly or entirely with asbestos
have also stood in the way of their use.
The object of the present invention is to obviate these objections, and to provide
means for the manufacture of asbestos insulated conductors at small cost and having
the properties requisite to admit of their use in armature windings, house-wiring,
and for like purposes.
According to this invention the wire after being first coated with a quick drying
adhesive material such for example as gum, is covered with asbestos fibre, wound
spirally or otherwise thereon, by any suitable mechanism well known to those
familiar with the art. The wire is then subjected to a finishing process consisting
in carding or brushing the asbestos covering to remove all superfluous lumps, and
irregularities, and laying the nap all in one direction, then applying pressure to the
covering whereby the fibre is matted together in a compact layer, the thickness
being gradually reduced to the required extent, and then applying a coating of
waterproofing and toughening material to protect the insulation from injury in
handling, and to impart to it moisture resisting properties. After these operations
the conductor is preferably passed between pressure rolls and drawn through dies
to impart a smooth finish and reduce the insulated conductor to an even diameter.
The brushing or carding of the asbestos fibre is an important step of the process
and contributes largely to the excellence of the finished product, and it is mainly to
admit of this operation being successfully performed that the wire is coated with
adhesive substance before applying the asbestos fibre, since it has been found
impracticable to raise the nap properly unless. the fibre is attached to the wire by
the aid of an adhesive material. The attaching of the fibre by means of an adhesive
substance and brushing, carding or raising the nap constitute important features of
this invention irrespective of the precise mode adopted for finishing the product.
The invention also includes a special and preferred form of apparatus for

page_text: combing or brushing the asbestos covering to remove all superfluous lumps and
irregularities, and for laying the nap all in one direction.
In the said improved apparatus a card or cards, in the form of a wheel, is or are
caused to revolve rapidly while passing around the circumference of the wire.
The desired results are thus produced in an efficient manner, and by adjustment of
the carding wheel the thickness of insulation may be reduced to any desired
extent.
Although this last feature is described in connection with and is particularly
applicable to apparatus for applying insulation to electrical conductors, the
invention herein embraces all other analogous uses to which it may be applicable.
In order that the said invention may be fully understood I will describe the
same with reference to the accompanying drawings, in which
Fig. 1 represents in plan and Fig. 2 in side elevation an apparatus for carrying
out the process according to this invention.
Fig. 3 is a side elevation of the carding or brushing devices, and Fig. 4 is an
end elevation thereof.
Figure 5 is an end elevation of a disc carrying one set of pressure rolls and
Fig. 6 is a longitudinal vertical section of the same.
Figs. 7 and 8 represent portions of a conductor drawn to an enlarged scale and
in two stages of the process.
Fig. 9 is a plan, Fig. 10 a side elevation, and Fig. 11 an end elevation of the
preferred napping apparatus, and Figs. 12 and 13 are details thereof.
Referring to Figs. 1-8 represents the conductor having a covering of asbestos
fibre applied and held thereon by means of a quick drying adhesive gum as already
described. Inasmuch as there are appliances in common use for wrapping wires
with fibrous material, any of which may be used for the purposes of this process, it
is not necessary to give a description of such apparatus.
All the moving parts of the machine are driven from a main shaft A through
suitable gearing, as clearly shown in the drawings.
The covered wire is subjected to the action of the carding or brushing devices
(Figs. 1 and 3). These devices comprise a suitable brush (or brushes) carried
by a disc B, each brush holder being adjustable radially on the said disc by
means of a screw 2. The disc B receives motion from the shaft A through a spur
wheel on the said shaft gearing with a pinione attached to the disc. The
pinion C, its hub, and the disc B are all provided with a central passage through
which the wire a passes.
To the disc B is secured a bracket e upon which the wire rests while under the
action of brush, and as the latter rotates, the map is raised and laid all in the
same direction, while all lumps and inequalities in the fibre are removed, bringing
the covered conductor more nearly to an uniform diameter.
After passing from the brush or brushes and through a guide D¹ the wire is
subjected to the action of pressure rolls g. In the machine shown there are two
sets of these rolls (designated E and F in Figs. 1 and 2) but there may be more or
less as desired.
The particular construction of these devices is illustrated in Figs. 5 and 6.
A dise E is mounted on or formed in one with the hub of a piniou e which receives
motion from a spur wheel G on the main shaft A. In this disc are three radial
slots in each of which is fitted to slide a block the three blocks being set at
120 degrees apart and adjustable radially by means of set screws". Each block f
carries at its inner end a rod or shaft g' arranged parallel to the line of travel of
the wire these rods constituting the axes or shafts of the three rolls g. The
pressure of the rolls y can be properly regulated by means of the set screws" sv
as to compress and mat the asbestos fibre and gradually reduce the thickness of
the insulated conductor to the required extent.
D2 D3 are guides through which the wire a passes after leaving the rolls g,
and H indicates a take up roll or pulley around which the wire is led and by which
the said wire is drawn through the napping and rolling devices hereinbefore

page_text: described. This take up roll or pulley is driven from the main shaft A by a
worm h worm wheel and pinions h¹ the latter gearing with a spur wheel H2 on
the axis of the said take up roll or pulley H. The wire passes from the roll or
pulley H between two rolls by means of which toughening and water-proofing
material is applied to the wire conductor. For this purpose any suitable material
having the desired properties, such as linseed oil, may be used with advantage.
The rolls are faced with felt or other absorbent substance, and the roll / dips
into a tank 1 containing the oil or water proof liquid the roll k taking a sufficient
supply thereof by contact with roll to apply to the conductor.
M, N represent two sets of finishing rolls, the axes of the two sets being at right
angles to each other. These rolls are provided for the purpose of smoothing down
the coating and removing the excess of oil from the conductor which finally passes
through a guide D₁, which may be a die to give it a final smooth finish and is then
wound onto a spool or reel P, rotated from the main shaft A through bevel
wheels p p pulley y, belt and pulley, the latter being on the shaft of the spool
or reel.
Obviously many variations may be introduced in the manner of finishing the
product after raising the nap in the manner described, and in the character of the
appliances used for performing the several steps of the process. It is also obvious
that some of the steps of the process and parts of the described apparatus may be
used without others."
The finished product has physical characteristics which distinguish it from other
insulated conductors heretofore made or known. The covering is dense and
compact, the fibres being well matted or felted together and adhering closely to the
wire. The surface is smooth and uniform and the covering very thin. An effective
insulation can be produced of a thickness less than 0.01 of an inch, which is of
great importance in windings for armatures and field coils. These qualities of the
finished product are due to the napping and compressing of the fibre, producing an
extremely tough, dense and coherent fabric, as distinguished from a series of coils
with more or less space between them, and with an inherent tendency to separate.
In point of economy the conductor made according to this invention compares
favorably with those which are insulated by a braided cotton covering.
For combing or brushing of the asbestos covering to remove all superfluous
lumps, and irregularities and for laying the nap all in one direction it is preferred
to use the apparatus illustrated by Figures 9 to 13 of the drawings and which may
be designated the "napper."
A represents the frame of the apparatus in which is mounted a shaft or spindle
carrying a spur wheel 2 to which rotation may be communicated from any suitable
source. This wheel gears with a pinion 3 on one end of a hollow shaft mounted
so as to rotate in a sleeve m on the frame A. On the end of this sleeve opposite
that on which the pinion 3 is mounted is a disc + and on the circumference of the
sleeve adjacent to the disc 4 are teeth which gear with a pinion 6, on one end of
a short shaft G which projects through the opposite sides of the disc 4. On the
end of this shaft G which projects through the side of the disc opposite to that
adjacent to the pinion 6 is mounted an adjusting arm L which carries the carding
wheel e and also a toothed wheel 7. Although a carding wheel is preferred, any
other analogous device suitable for the purpose may be employed.
The adjusting arm L is shaped like a bell crank lever, and is pivotted to the
shaft G at or near the point of the angle. On one arm of this lever is a pin G
upon which the carding wheel e is rotated by means of a pinion 8 thereon gearing
with the spur wheel 7, and in the end of the other arm of the lever L is a slot 9
through which a set screw 10 passes into the face of the disc 4. By loosening
this set screw 10 the arm or bell crank lever L may be turned on its pivot G and
the axis of the carding wheel be caused to describe an arc which if extended would
intersect the orifice of passage o in the sleeve 3, through which the covered wire
to be operated upon is led to the carding wheel. It will thus be observed that by
adjusting the position of the carding wheel the thickness of the covering on the

page_text: electrical conductor can be regulated. The rotation of the disc 4 through the
toothed wheels 2 and 3 causes the napping wheel a to be rapidly revolved as it is
carried around by the disc, through the gearing 6, 7 and 8, the pinion 6 gearing
with the stationary teeth on the sleeve m.
In order to properly support the wire while subjected to the action of the
carding wheel a suitable holder is provided consisting of a tube 11 proportioned
according to the size of the wire being operated upon, which passes through it,
the said tube being cut away for a portion of its length on one side as at 12, s
as to allow the teeth of the carding wheel to reach the surface of the insulating
covering on the wire. 13 is a plate in one end of which is a hole for the receptio i
of the tube 11 and in which it is secured by a set screw 14 at right angles thereto.
The plate 13 is pivotted to the face of the disc + by a screw 1 and is held in its
adjusted position by a set screw 16 passing into the disc 4 through a slot 17 in the
extremity of the arm 13.
From the passage o, through the hollow shaft 3", the wire passes through the
tube 11 where it is operated upon by the carding wheel at the point where it is
exposed through the cut away portion 12 of the said tube. In order to keep the
wire firmly seated against the wall of the passage through the tube 11, while it is
being operated upon, as in cases where the diameter of the wire is somewhat less
than the diameter of the passage in the tube, the holder is capable of a slight
adjustment by means of the set screw 16 which passes through the slot 17 s
already described. Different sized holders are however provided to conform as
nearly as possible to the diameter of the covered wire.
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed, I declare that what [
claim is :-
1. The process of applying a fibrous insulating covering, such as abestos, to an
electrical conductor, consisting in coating the conductor with an adhesive substance,
wrapping or winding the fibre thereon, brushing or carding the latter to raise a
nap and then pressing or compacting the fibre, substantially as hereinbefore
described.
2. The described process of manufacturing insulated electrical conductors, which
process consists in coating a wire with adhesive substance, wrapping it with fibrous
asbestos, brushing the fibrons coating to raise the nap and lay it in one direction,
compressing it between pressure rolls, coating with waterproof material, and
subjecting it to a final rolling to produce a smooth finished surface, as hereinbefore
described.
3. In an apparatus for the manufacture of insulated electrical conductors the
combination of devices for feeding a wire longitudinally, a rotating brush or
carding device having its axis of rotation coincident with the axis of the wire,
and means for compressing and matting the fibre, substantially as hereinbefore
described.
4. The combination of mechanism constituting the napper and comprising the
revolving carding wheel arranged and constructed substantially as hereinbefore
described and illustrated in Figures 9-13 of the accompanying drawings.
5. As a new article of manufacture, the electrical conductor having a compact
insulating covering of water-proofed a-bestos fibre, produced as liereinbefore
described and having the characteristics set forth.
Dated this 26th day of February 1895.
JOHNSONS & WILLCOX,
Agents.