Insulated Electrical Conductors.
Year: 1887

page_text: Date of Application, 17th May, 1887.
Specification Accepted, 12th July, 1887.
Insulated Electrical Conductors.
I, JAMES TATHAM of 226 South Fifth Street in the City of Philadelphia, State of
Pennsylvania United States of America, Lead Pipe Manufacturer do hereby declare
the nature of this invention and in what manner the same is to be performed, to be
particularly described and ascertained in and by the following statement :-
The object of my Invention is to protect from injury by heat the insulating
covering of an electrical conductor which is being sheathed with lead or other ductile
metal in apparatus similar to an ordinary lead pipe press and this object I attain as
hereinafter set forth reference being had to the accompanying drawings in which
Figure 1 is a longitudinal section of sufficient of a lead pipe press to illustrate the
means which I have devised for carrying out my Invention. Figures 2 and 3 are
enlarged sectional views of part of the press. Figure 3 showing a slightly modified
form of the apparatus and Figure 4 is a sectional plan on the line 1-2 Figure 2.
The press may be similar in its general construction to that set forth in my Letters
patent No. 11879 dated October 6th 1885 except in the particulars hereinafter
described and claimed.
A is part of the hydraulic cylinder of the press and B the plunger carrying the
lead reservoir D and hollow column F the press having the usual cap plate H to
which is secured the pendent hollow ram G through a suitable plug at the lower end
of which passes the hollow core N which is supported by a block J contained within
the lead reservoir and resting on the hollow column the said hollow core N having a
detachable nose P tapering from butt to point and terminating in the opening of the
die M which is secured to or is carried by the base plate of the core holder.

page_text: The insulated conductor which is to be provided with a coating or sheathing of
lead or other ductile metal passes down through the hollow core and through the die
and as the reservoir D is raised the lower end of the ram pressing upon the lead
contained in the reservoir forces the lead out through the die and round the conductor
as the latter issues from the end of the hollow core.
In treating wires which have a coating of gutta percha or other insulating material
liable to be burnt or injured by heat, it is necessary to provide means for preventing
or retarding the transmission of heat from the lead to the conductor passing through
the interior of the core, and it has been proposed to cause a circulation of water
through the hollow core for this purpose.
I find however, that something more than the circulation of water through the
hollow core is necessary to prevent the destruction of the insulating covering of
the conductor, for if the lead possesses a high degree of heat when applied to the
insulated conductor as it passes through the die, the effect of the refrigerating
core is neutralized, as will be readily understood.
In carrying out my invention, therefore, I always allow a considerable portion of an
old charge of lead to remain in the lower portion of the cylinder at the end of
each operation of the press; for instance, in the press shown in Figure 1, a portion
of the old charge extending up to the level shown by dotted lines, must remain in
the cylinder, owing to the fact that the block prevents a further entrance of the ram
into the cylinder.
The remaining portion of the old charge is of comparatively limited volume,
owing to the fact that the core supporting block J occupies the greater portion of
the lower end of the cylinder, and this block and the core supporting nose are so
cooled by the circulation of water or other cooling medium through the core, that
they tend to reduce below the point of danger, the temperature of the lead remaining
in the cylinder.
The volume of the old charge which remains in the cylinder is such, however, that
before the first portion of the new charge can reach the die and be brought into
contact with the insulating covering, the temperature of the fresh supply of metal
will have been reduced below the point at which it is injurious to said covering.
It will thus be seen that all portions of the conductor which are in proximity to the
hot metal of a fresh charge are protected by the circulation of water throughout the
hollow core, and that after the first charge there is no chance for any of the metal of
a new charge to reach the insulating covering of the conductor until the temperature
of the metal has been reduced below the danger point.
Various means may be adapted for causing a circulation of water through the
hollow core of the press.
I prefer, however, to provide the hollow core with a water inlet pipe b, extending
down to the lower portion of the annular space d which intervenes between the outer
shell of the core and the central tube which encloses the conductor, the cold water
being thus delivered directly at the lower end of the core, where it is most needed, and
the water rising through the annular space d and escaping through the pipe g at
the top.
The central tube fis preferably of sufficient diameter to contain a supply of oil or
other insulating material which surrounds the insulated conductor down to the point
of issuance of the latter from the nose of the core, and thus aids in preventing the
undue heating of the insulating covering of the conductor during the passage of the
latter through the core.
If desired, the nose of the core may be made hollow and the water inlet pipe may
be carried down into the same as shewn in Figure 3.
Other means than the core supporting block J may, if desired, be used as a stop for
determining the extent of penetration of the ram, but the block J being already in
position and available as a stop, its use for this purpose is preferred.
The use of the core supporting block J is an important element in the proper
carrying out of my invention, for as before remarked, this block occupies a large part

page_text: of the lower portion of the lead. cylinder, so that the actual volume of the lead
contained in the cylinder up to the level of the top of the exposed portion of the nose P
of the core, is but small, and the heat imparted thereby to said nose is much less than
if the latter were entirely surrounded by a mass of lead extending to the wall of the
cylinder, as for instance, in the machine shewn in Bishop's United States Patent
No. 18,131, September 8 1857.
The circulation of water in the core so reduces the temperature of the supporting
block and core nose that the heat contained in the limited body of lead left in the
body of the cylinder is not sufficient, in practice, to effect, during the time required
for recharging said cylinder, an injurious heating of the insulating covering of the
conductor, especially when the latter is surrounded by liquid insulating medium, as
described.
The upper part of the block which supports the hollow core is, however, much less
in diameter than the lower part, so that the upper portion of the mass of lead left in
the cylinder is of considerable bulk, hence, while the old charge is being forced from
the cylinder, ample time is afforded for the welding of the old and new charges, so as
to avoid defective joints in the sheathing, the heat of the larger mass of lead which
surrounds the upper portion of the core block having no injurious effect on the
insulating covering of the conductor, owing to the fact that the water chamber of the
core extends for a considerable distance below the top of said core supporting block.
In the machine shewn in the Patent of Bishop, before referred, to, the water used
for cooling the hollow core descended an outer annular passage in the latter and
ascended an inner annular passage in direct contact with the conductor passing
through the core.
In my machine, however, the conductor passes through a central tube in the core,
and this is essential, even if insulating liquid is not used for surrounding the
conductor, otherwise, the water adhering to and carried down by the covering of the
conductor, will not only cause defects in the leaden sheathing but will also injuriously
affect the insulating properties of the covering.
The water descending the annular passage in the core of the Bishop machine,
moreover, was in contact with the heated shell of the core hence when it reached the
lower end of the core it was highly heated, whereas when the cold water is introduced
through a pipe discharging near the delivery end of the core, as in my machine, a
much lower degree of temperature can be maintained at said delivery end of the core
than is possible when the plan shown in Bishop's Patent is adopted.
A core-supporting block, substantially such as I now use is shewn in my Patent
No. 11,879 dated October 6th 1885, before referred to. Such supporting block alone;
however, is not under all circumstances effective in preventing injury to the insulating
covering of the conductor by heat but when the block is used in combination with a
water circulating core the temperature of said block and the core nose are so reduced
that they can readily counteract the effect of the heat contained in the small body of
lead left as part of the old charge in the bottom of the lead cylinder.
The use of insulating material in the tube around the conductor may be dispensed
with if desired, although its use is preferred.
Having now particularly described and ascertained the nature of said Invention
and in what manner the same is to be performed I declare that what I claim is :-
First In apparatus for covering insulated electrical conductors the hollow core
forming a passage for the insulated conductor and having a chamber for the
circulation of a cooling fluid, in combination with a core-supporting block, contained
in the delivery end of the lead cylinder, and serving as an aid to the core in
preventing the undue heating and consequent impairment of the insulating covering
of the conductor all substantially as hereinbefore described. .
Second-In apparatus for covering insulated electrical conductors the hollow core
forming a passage for the conductor, and having a chamber for the circulation of the
cooling fluid said passage and chamber having no communication with each other,

page_text: whereby the access of the cooling fluid to the insulating covering of the conductor is
prevented, all substantially as herein before described.
Third: In apparatus for covering insulated electrical conductors the hollow core,
forming a passage for the conductor and having a chamber for the circulation of
cooling fluid, and a fluid supply pipe discharging close to the delivery end of the core
all substantially as hereinbefore described.
Fourth-In apparatus for covering insulated electrical conductors the hollow core,
and its hollow nose, in combination with a fluid supply pipe discharging directly into
the hollow nose of the core substantially as hereinbefore described.
Fifth The protecting of insulating conductors while the same are being sheathed.
in a pipe press by surrounding the conductor with liquid insulating material until it
issues from the core, and circulating a cooling fluid through the core between said
insulating liquid and the hot sheathing metal outside of the core, all substantially as
hereinbefore described.