Year: 1886

page_text: I ALFRED JULIUS BOULT of 323 High Holborn in the County of Middlesex,
Engineer do hereby declare the nature of this invention (a communication from
William M. Habirshaw of New York, 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 great object of this invention is to enable electric wires to be covered with
a smooth uniform coat of vulcanized rubber without waste of insulating material
and in a manner which will ensure tight joints and rapid and easy manufacture.
Heretofore wire has been covered by plastic strips of soft unvulcanized rubber
wound on spirally with the edges overlapping, and afterwards vulcanized in such
overlapping layers Wire has also been covered with two longitudinal strips of
plastic rubber curved around each half of the wire by rollers, and united at the
edges. In the latter system in order to have the joints secure the strips must be
inade much wider than the circumference of the wire to allow the strips to be
firmly rolled onto and united about the wire, and to admit of the excess being
pinched or cut off at the joints, which caused a great waste of material that greatly
enhances the cost of manufacture. In the spiral overlapping system, owing to the
soft yielding nature of the plastic rubber strips, little or no tension can be applied
thereto in the winding operation, so that the.strips cannot be wound in a perfectly
tight manner and hence loose joints and imperfect covering is therefore likely to
result. Moreover, the overlapping spiral joints cause unevenness in the covering
of the wire and an appreciable waste of vulcanizable material, which is objection-
able.
In order to avoid some of the objections to the spiral system it has been
proposed to cover wires with successive series of fibrous tapes, saturated or coated
with films of soft vulcanizable rubber each layer of tape being wound on in réversé
spiral direction with edges overlapping.
This system owing to the thinness of each tape with its rubber film will reduce
the unevenness owing to the spiral overlapping joints but the insulating covering

page_text: is in this case composed chiefly of cotton or fibrous material whereas it is more
desirable to obtain a deep substantial coating of solid rubber.
Now according to this improvement a deep substantial coating of solid vulcanized
rubber with tight joints and without any waste is secured This is accomplished
by first preparing a plastic strip of soft unvulcanized rubber of substantial thickness,
which strip is mounted on a sustaining core or layer of cloth metal or other
material which sustains the yielding strip and prevents it from stretching or
yielding longitudinally and which strip is wound spirally about the wire with the
soft plastic rubber in contact with the wire and with the edges of the plastic strip
abutting directly together. By this means the strip can be wound tightly about
the wire with all the desired tension, as the sustaining core or web resists the
tension and prevents the yielding of the strip and as the edges abut the joints will
be closed tightly and the surface of the covering will be smooth and even without
protuberances and there will be no waste whatever in the application of the strip,
besides, the actual length of the joints will be much less than in the longitudinal
system, thereby effecting an important improvement. After the strip is thus
wound on the wire, it is then passed through rollers which compact and consolidate
'the rubber about the wire, causing the spiral abutting joints to be pressed firmly
together and to become practically obliterated rendering the coating integral and
continuous, and making the external surface perfectly smooth. After the rolling
operation a tape thinly saturated or coated with an adhesive rubber film on its
inner side is wound spirally about the spiral rubber coat with its edges overlapping
after which the coatings are vulcanized on the wire, which thus completes the
manufacture. This invention therefore consists in the features here outlined as
hereinafter fully set forth.
In the drawings annexed Figure 1 presents perspective views of three forms of
plastic strips, preferably vulcanizable with which the wire is covered according to
this system.
Figure 2 shows the first operation in covering the wire one of the strips shown
in Figure 1 being wound on to the wire.
Figure 3 shows the second operation where the wire with the strip wound
thereon is passed between grooved rollers.
Figure 4, illustrates the third operation where the outer tape is wound over the
underlying rubber coat.
Figure 5 represents the finished wire.
.
In practising this invention the insulating material is prepared in long plastic
strips such as shown at A. B. C. in Figure 1 preferably of soft unvulcanized rubber,
although other suitable insulating material may be used. The width of these
strips is preferably equal to the circumference of the wire to be covered, but this
width may be less or more without objection and its thickness will be substantial
but will vary with the size of wire and the degree of insulation desired as will be
readily understood. These plastic strips are however, prepared with a core
foundation or sustaining web d of thin sheet metal woven cloth, paper, or any
other suitable material which is quite flexible but substantially non yielding in a
longitudinal direction upon which core one or more layers c of soft unvulcanized
rubber of substantial thickness is sustained and adhered as shown best in Figure 1.
The rubber layer c may be equal on each side of the core web as seen at A, the
web being the same width as the rubber, or the rubber may be all on one side of
the web as seen at B or the web may be narrower than the rubber and be
⚫embedded in the middle as seen at B. The core web d may be made of woven
fabric or of paper or sheet métal or any other suitable inaterial but it is preferable
to make. it of metal as this will serve another important purpose hereafter
explained. In any case it is preferable to wind the strip on the wire with the soft
rubber layer in contact with the wire, and tlie core either on the outside or in the
middle of the strip, the latter being the best, as shown at A and C. The insulating
material shown at A and B may be first formed in large sheets wound up on
.i
I S

page_text: drums and thence cut into narrow strips in the manner well known in the manu-
facture of rubber goods, and requiring no special description here. The form
shown at C will require to be first cut in separate strips of the desired width and
then rolled together to make the complete strip.c, c, d as shown. Hence the forms
shown at A. B. are the simplest and most easy to manufacture, and are therefore
preferable.
The strips having been properly prepared, as described, the naked wire his first
passed through a bath D of pure rubber cement, as shown in Figure 2 and after a
sufficient length of the cemented wire has passed through the air or over a heater
to set the cement one of the strips A is wound spirally on the wire with the
edges closely abutting, as indicated in Figure 1. The face of the strip being soft
and plastic and unvulcanized will adhere at once to the surface of the wire or to
the rubber film thereon and the edges of the plastic rubber abutting closely together
spirally will adhere and form a smooth continuous tubular coating about the wire
free from protuberance and adhering uniformly to the wire all along its length,
instead of making imperfect internal contact with the wire and showing external
protuberances as is the case with the spirally overlapping system heretofore used.
And as the plastic strip is strengthened by an unyielding web or core, any desired
tension may be put upon the strip in the winding operation to ensure its being
wound closely and tightly on the wire with the edgos brought into firm and
adherent contact.
:
After the plastic strip is thus wound about the wire the spiral joints will be
close and even but will be still visible and in order to compact this coating and
render the joint more perfect; the coated wire is then passed between grooved
rollers E, as seen in Figure 3, the grooves being of sufficiently contracted size to
ensure a compression of the coating so that the wire will issue from the rolls with
the rubber tightly compacted about the wire with the spiral joints closed firmly
together and their appearance practically obliterated rendering the coating
practically a continuous integral tubing and making the exterior smooth as
shown in Figure 3.
The wire after passing from the rollers as in Figure 3 may be vulcanized and
will be then fitted for use but it is preferable to further protect it before
vulcanizing. Hence after the coated wire has been rolled it is then provided with
an external winding of tape g or other fibrous or sheathing material as seen in
Figure 4 preferably coated on the interior with a thin film of a plastic vulcanizable
rubber compound, or what is known as "friction tape." This "friction tape" g is
wound preferably in a reverse direction to the underlying rubber coating, and withi
its joints spirally overlapping as well shown in Figure 4 This tape will adhere
firmly to the rubber and to itself in its overlapping joints and form a strong
protecting sheathing to the inner rubber coat as will be readily appreciated.
'
When the outer tape is wound as described and the wire rolled up on drums, the
drums are then placed in the vulcanizers and the coatings vulcanized on the wire,
which thus finishes the operations and renders the wire ready for use as indicated
in Figure 5.
It will now be seen that in this system the main covering strips of rubber
compound are applied to the wire without any waste whatever and produce at the
same time an even uniform and continuous coating without protuberances and
with very close and perfect joints, and moreover the actual length of the joints
will be about one third less than in the longitudinal system where two strips are
united on opposite sides of the wire and hence much more economical and much
more perfect work is produced for not only is material saved and work expedited
but a more perfect internal contact and external form secured and the length of
joints are greatly reduced, which are most important advantages.
It will be further seen that in case the strips are prepared with metallic cores.
or webs d as described that not only will the rubber be greatly strengthened
and enabled to be wound tightly about the wire but this metal core will form a

page_text: distinct conductor within the covering parallel with the central wire and which
may be used for a return conductor or for other purposes which will suggest
themselves to the electrician. For this latter purpose it is therefore preferable to
have the metal core strip d of such thickness as will equal the conductivity of the
wire h
Having now particularly described and ascertained the nature of the said
invention and in what manner the same is to be performed as communicated to
me by my foreign correspondent I declare that what I claim is :-
1. Wire coated with a plastic insulating strip of substantial thickness wound
spirally about the wire with its edges abutting and adhering substantially as set
forth.
. 2. Wire coated with strips of plastic insulating material of substantial thickness
mounted on a sustaining web or core longitudinally unyielding and wound with
tension spirally about the wire with its edges tightly abutting substantially as
herein set forth.
3. Wire coated with strips of plastic vulcanizable rubber wound on spirally
with the edges abutting and adhering and subsequently vulcanized thereon
Bubstantially as set forth.
4. Wire coated with plastic strips of substantial thickness wound on spirally
with the joints abutting and subsequently compressed and compacted by rolling
substantially as set forth.
5. Wire coated with plastic strips wound on spirally with the edges abutting
subsequently rolled and finally overwound with a sheathing tape or strip with
edges overlapping substantially as set forth.
6. Wire coated with strips of plastic unvulcanized rubber wound on spirally
with the edges abutting and adhering, subsequently compacted by rolling and then
overwound with a sheathing tape or strip and finally vulcanized substantially as
set forth.
7. Wire coated with an inner coat of plastic rubber compound wound on spirally
with the edges abutting and adhering thence compacted by rolling and overwound
with an external sheathing of tape or its equivalent wound in reverse inclination
to the inner coat, with its edges overlapping and the whole finally vulcanized
substantially as set forth.
8. Wire coated with an insulating strip prepared with a sustaining core or web
of metal wound spirally about the wire, substantially as and for the purpose set
forth.
9: Wire coated with plastic strips of vulcanizable rubber mounted on a
strengthening core or web of metal wound spirally about the wire with the
edges of the rubber abutting and the metal out of contact with the wire adapted
to form a secondary or return conductor substantially as shown and described.
Dated this 30th day of March 1886.
ALFRED J. BOULT.