Year: 1893

page_text: Date of Application, 9th Nov., 1893-Accepted, 16th Dec., 1893
at these angles or bends, I may, however, have the wire perfectly straight but
touching a diaphragm or its equivalent only, whereby it does not come into contact
with the surrounding tube at all and thus the static capacity is lessened as much
as practicable.
One way of accomplishing this is set forth in Figure 1.
In this :-
A, is a hollow mandrel; B a strip of paper or other insulating material equal
in breadth to the outer circumference of the hollow mandrel A; C a second strip
of insulating material wound spirally round the strip B. There may be more than
one of these strips C.
The wire D, whether bent in a zig-zag form or with projecting bends or straight,
is fed into tube A. Ribbon B is fed also at the same speed and preferably parallel
so as to form a non-extensible tube on which the spiral ribbon C can be wound.
The ribbon B thus forms a tube support for ribbon C as it leaves the mandrel.
These ribbons can, if desirable, be steeped with any non-conducting composition.
Two tubes formed in this manner are now brought together and at the same time
twisted round each other somewhat, the section being as set forth in Figure 2.
They are then passed successively through two dies, by which they are pressed into
the shape successively of Figure 3 and Figure 4. They thus form a single
cylindrical body with a diaphragm of insulating material separating the lead and
return wires or, if desirable, two wires having the same polarity. The tube can
be made of any other shape than circular by means of dies. A series of these.
insulated conductors can be combined together in the manner set forth in Figure 5,
each strand passing through dies in such manner as to shape them to the exact
segments required to make a solid cable. These are preferably twisted round
each other and can be encased in a lead tube in the usual manner.
It will be obvious that, once suggest this plan of shaping tubes by passing
through dies, other forms can be used in the same way.
Further, the wires, instead of being round, especially when two contiguous wires
have the same polarity, can be shaped hemispherically, thus forming a single
cylinder with a paper or other diaphragm between the two halves. In submarine
cables where great strength is required, it may be necessary to form the insulating
material of solid gutta percha or similar substitute combined in order to withstand
the pressure. For this purpose I use an apparatus somewhat similar to the ordinary
lead press.
1

page_text: Figure 10 being a longitudinal section, and
Figure 10 plan of portion of Figure 10,
Figure 11 being a transverse section.
In these, A' is a hollow die, B' B' a core, C' the lead which can be either a
single or stranded wire, or a tube such as already described containing either one
wire or two wires separated by a diaphragm, or other form of cable; D' gutta
percha.
The die (or die and core) are caused to rotate by means of gearing F F, or
other mechanism, so as to give a twisted form to the gutta percha; the cable can,
however, be caused to rotate instead, but this is hardly as good an arrangement.
It is obvious that several layers can be applied by means of presses, the cable
passing from the die of Figure 10, entering another die and core, and receiving a
fresh layer of gutta percha, lead or other material.
A special revolving die is only needed for the first layer and then only when
there are less than three ribs, I prefer, however, a single and spiral rib as that
gives a cable with minimum static capacity; if, however, it touch at three points
as shown in the drawings, the die can be three lobed and stationary.
Having now particularly described and ascertained the nature of my said inven-
tion and in what manner the same is to be performed, I declare that what I
claim is :-
1. In the manufacture of electric cables, passing a wire through a hollow
mandrel, passing at the same speed a longitudinal ribbon of insulating material
over the mandrel and curving it round so as to form a tube and coiling one or
more ribbons of insulating material round said tube.
2. In the manufacture of electric cables, taking a series of hollow tubes containing
an electric wire with air space and twisting these tubes together and passing them
them through a die whereby they are formed into a single cylinder of suitable
shape with transverse diaphragms separating the wires which are held near the
centre of the group by the twist.
3. In the manufacture of electric cables, forming the wires bent or zig-zag in
tubes of much larger diameter than the wires, substantially as set forth in
Figures 7, 8 and 9.
4. The manufacture of electric cables by squirting or pressing gutta percha or
equivalent material so as to form a solid tube surrounding the wire but of much
larger diameter than the wire, and arranging a series of one or more straight or
spiral ribs or one spiral rib approaching the centre of the tube to within about the
distance of the radius of the wire and covering them as required, also the improved
cables themselves thus formed.
5. The apparatus for forming electric conductors, consisting of a press similar
to a lead press having a die A' and core B¹, the former having a portion or portions
cut away so as to form projecting ridges on the tube formed, and means F for
rotating the said die A¹, set forth in Figures 10 and 11.
6. An electric cable formed with the conductor only touching the side of the
containing tube at intervals, or formed with bends or zig-zags substantially as
described.
Dated this 8th day of November 1893.
WM. P. THOMPSON & Co.,
Of 6, Lord Street, Liverpool, Patent Agents for the Applicant.