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Патент USA US2407355

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Filed Dec. 24, 1943
'2 Sheets-Sheet 2v
JOSHUA C. Qua YLE 2 Farm Jams
I nventors ‘
Patented Sept. 10, 1946
George Hall Walton, Helsby, near Warrington,
Joshua Creer Quayle, Helsby, and Peter Jones,
Kelsail, near Chester, England, assignors to
British Insulated Cables Limited, Prescot, Eng
land, a British company
Application December 24, 1943, Serial No. 515,506
In Great Britain January 1, 1943
8 Claims.
(Cl. 154—2.26)
In the covering of wires with insulating mate
rial by the so-called longitudinal method, two
sheets of unvulcanised rubber in the form of long
strips are passed longitudinally between a pair of
circumferentially grooved rolls With a group of
parallel wires between them. The grooves in the
rolls register with each other and form at the nip
circular apertures or passes through each of
which passes a wire with parts of the two sheets
of insulating materiah one forming the upper
and the other the lower half of the covering of
the wire. At each side of each groove the two
sheets of rubber are very forcibly compressed so
that they are almost severed and seams are
formed at each side of the wire betv com the upper
sheet and the lower sheet by the forcible com
pression of the insulating material there. These
machines were developed on the basis of the use
of sheets of unvulcanised rubber compound which
possess the property of forming a seam under
compression at normal atmospheric temperatures.
In the invention set out in the application for
Letters Patent No. 472,338 the longitudinal ma
chine is adapted for use with other materials, for
instance, plasticised polyvinyl compositions which
about to enter the nip, heating by a high fre
quency electric ?eld is effected by feeding high
frequency current to the wires in such a way as to
establish a field in the insulating material when it
comes close to and in contact with these wires.
In doing this advantage is taken of the resonant
e?ect of an insulated line for the purpose of
producing a rise of voltage between the point
of feeding the wires and the point at which the
10 high frequency heating has to become e?ective.
This rise of voltage is, as is well-known, dependent
upon the distance between the point of feeding
the line and the point of terminating it and on the
nature of the termination. The best distance is
15 in the neighbourhood of a quarter of the wave
length corresponding to the high frequency volt
age applied. Since the termination in this case
will have the character of capactitative reactance
combined with resistance, the distance between
20 the point of feeding and the point of terminating
will ‘be somewhat less than a quarter wave length
and can be found readily by experiment.
Since it is contemplated that for this heating a
frequency of the order of 20 million cycles per
25 second and upwards will be used, it will be seen
that the length in question is not an inconvenient
require to be at a temperature substantially above
normal atmospheric temperature in order that
Three embodiments of the invention are indi
satisfactory seams can be made by compression
cated in the accompanying diagrammatic draw
between the rolls.
In that improved machine the heating of the 30 mgs.
In Figure l, which is a side elevation, an ar
sheets of insulating material is effected by passing
rangement is indicated such as described in the
each sheet by itself, or with the other sheet,
said specification for heating the two sheets of
through heating means, as the sheets are ap
insulating material by high frequency electric
proaching the grooved nipping rolis. The pre
ferred means of heating is by the utilisation of the 35 fields as they are approaching the rolls and the
present invention is shown as an additional heat~
effect of a high frequency alternating or ?uctuat
ing means in such a machine. In the other lig
ing ?eld, through which the material passes as it
ures the apparatus for heating the sheets of mate
is approaching the rolls and arrangements are
rial as they approach the rolls is not shown, only
mentioned in which electrodes are arranged near
the path of the sheets, or each sheet of material, 40 those parts being indicated which represent the
so that as the material moves past these elec
present invention.
Figure 2 is a plan view corresponding to Figure
trodes it is subjected to a, high frequency electric
?eld, either between a pair of electrodes or be
Figure 3 is a side elevation of another arrange
tween the wires and an electrode.
It is also mentioned in the said speci?ca 45 ment and Figure 4 is the corresponding plan view.
A third arrangement is shown in Figure 5 in
tion that it may be advantageous to supplement
side elevation and in Figure 6 this is shown in
this heating by some localised treatment of the
plan view.
sheets as they approach the nip. The present
The sheets of insulating material i and 2, as
invention makes an addition to or modi?cation‘of
the machine described in the said speci?cation by 50 shown in Figure 1, approach the grooved rolls 3
by paths which lead each of them between the two
which heating is provided in the immediate
electrodes of a high frequency electric ?eld sys
neighbourhood of the nip with very simple
tem. These consist of a lower electrode formed
changes in the apparatus. In accordance with
the invention, in a machine in which the two
sheets of material are kept apart until they are
of a metal band 4, passing round a pair of rollers
5, and- an upper electrode which is a stationary
plate 6. The moving band 4 facilitates the travel
of the sheet of material which rests on it and
which moves without touching the stationary
two small capacities in series at the rolls, each of
these capacities being formed by a group of wires
l’, the dielectric consisting of the sheets of ma
electrode 6. The moving band is at ground po
tential and the stationary electrode receives the
high potential. From the left-hand ends of the
terial i and 2 and the second electrode pro
vided by the rolls 3. Into this line is fed high
frequency current by means of the coupling loop
bands ‘4 the two sheets of material move respec
ll placed near the voltage nodal point 9 and
tively downward and upward and come together
connected with the oscillator [9.
at the nip of the rolls 3, resting against these
The arrangement shown in Figures 3 and 4 is
rolls during the last part of the movement. In 10 similar in principle to that just described, but
the space between the two sets of electrodes 4 and
provides a better utilisation of the width of the
6 run horizontally a set of parallel wires ‘i which
rolls 3 since it is unnecessary here to provide a
are aligned with the grooves in the rolls 3 so that
clear space between the two sets of wires 1 at
each wire when passing through the nip of the
the rolls
At this end of the line the wires
rolls lies within a groove and is enclosed between 15 approach together as shown clearly in. Figure 4.
portions of the two sheets of insulating material
They are separated into two sets by guides l2
I and 2. This material, which may, for instance,
and it. Each of the guides i2 is a block of in
be a plasticised polyvinyl compound, requires to
sulating material, standing vertically, with holes
be heated sufficiently to become soft and ad
for the wires arranged in a vertical line. The
hesive so that by the compression of the parts of
guide members l3 are vertical bars of conduct
the rolls between the grooves the material is made
ing material which are both grounded and there
to ?OW laterally into the grooves and is caused
by conn ected together and form, not only a guide,
to make a seam at each side so that it proceeds
but a short-circuiting connection at the nodal
beyond the rolis as a tube 8 enclosing a wire, the
point. By this arrangement of guides and by
several tubes being connected only by very thin
appropriate means for leading the wires from the
webs of material so that the covered wires can be
supply bobbins to the guides I3, the wires are
easily separated from each other.
divided into two vertical sets until they reach
To ensure that the two sheets of material
the guides i2 from which point they begin to
shall be at the right temperature at the moment
turn into a single horizontal plane which they
of coming into contact in the nip of the rolls 3, _
reach at the nip of the rolls 3. The feeding
heating localised in that region is provided in
in this case is also done by means of a loop ll
accordance with the present invention by setting
receiving high frequency current from an oscil
up a strong high frequency electric field between
lator (not shown).
the wires l and the rolls 3. This ?eld passes
In the arrangement shown in Figures 5 and 6',
through the sheets of insulating material I and
the wires ‘i are used in a single set as one side
2 and generates heat therein by dielectric loss,
of the line, the other side being provided by
the heating being most intense in the direct
a strip M of metal arranged below the wires 1
neighborhood of each wire.
and connected at the right-hand end to the
The present invention provides for obtaining
short circuiting bar l5 which is grounded and
the necessary high voltage between wires '1 and
locates the nodal point. At the left-hand end
rolls 3 in a most convenient manner. It takes
the strip It makes contact with one of the rolls
advantage of the well-known fact that a con
3 by means of brushes It. The two rolls are
ductor in a resonant line having a length ap»
connected together electrically by their hous
proximately equal to one-quarter wave length
corresponding to the frequency of a high fre
ing. In this case the housing and the rolls are
insulated from ground, as indicated diagram
quency electric supply system will have on it a
matically by the insulated platform I‘! shown
standing wave» of electric potential and another
in Figure 5. The feed to the line could in this
inversely disposed standing wave of electric cur
also be by way of a loop placed between
rent so that it can be fed at the low potential
the wires 1 and the strip [4, but an alternative
end with a substantial current and will exhibit 50 arrangement is shown in which the feed is by a
at the other end a high potential difference
conductive connection from the oscillator l9 by
and a small or zero current. The wires 1 of
the present case are made to serve as such a line,
way of the short circuiting bar 15 and another
the feeding end being that remote from the rolls
so that the high potential end is at the rolls.
Three systems by which this is carried out are
shown in the drawings. In each of them the
dimension which approximates to one-quarter
wave length is indicated by L. The feeding end is
near the right-hand end of this length in each
case so that the high. potential end is at the
insulated from ground.
left-hand where the rolls are situated. .
In the arrangements shown in Figures 1 and 2
two sides of a line are provided by two groups
of wires ‘i which are spaced apart laterally. The
nodal point, i. e., the voltage minimum point, is
located by the grounded short~circuiting bar 9
across and in contact with which all the wires 1
bar I8 placed a short distance away from it and
The arrangement shown in Figures 5 and 6 has
a combination of advantages of simplicity, con
venience and efficiency. but other dispositions
of the parts of the machine are possible using
the wires in one set as one side of the line.
The arrangement shown in Figures 5 and 6
also has the advantage that the high frequency
?elds are mainly located in the space between
the wires and the strip l4 so that losses in the
surrounding bodies are small.
It will be seen that the additional heating
means provided by the present invention can
very conveniently be applied to the wires as they
are led into the machine and thereby heat can
run. Near the rolls 3 the wires are supported
be generated in the insulating material at the
on an insulating bar iii. This is provided solely 70 point where the highest temperature of this ma
for the. purpose of raising the level of they wires
terial is required and this is done in a way which.
slightly. for convenience in the disposition of
the apparatus. The arrangement described pro
vides a quarter-wave length line short circuited
at the voltage nodal point and connected through
facilitates the disposition of the high voltage part
of the apparatus.
What we claim as our invention is:
1. Apparatus for heating pairs of strips of or
wires of one group lying in one plane and the
ganic resin insulation by dielectric loss as they
wires of the other group lying in another plane
enter the nip of a pair of cooperating electrical
parallel therewith, and means located near to
ly conducting rolls having a plurality of opposed
the rolls for bringing all the wires into one plane.
grooves therein, each pair of grooves de?ning a
5. The apparatus de?ned by claim 1 having
pass for continuously applying said strips as a
one side of the said line constituted by all of the
coating to an electrically conducting wire trav
said wires in parallel and the other side by an
elling through said pass and seaming together
electrically conductive member extending along
the strips applied to each wire, said apparatus
side said wires between the said connecting means
comprising a capacitor formed by the insulation
strips together with the rolls and the portions 10 and the rolls, and means for coupling said mem
her at one end thereof to the said connecting
of the wires in the nip thereof, a resonant trans
means and at the other end thereof to the rolls.
mission line having two parallel sides so connect»
6. The apparatus de?ned by claim 1 having
ed to said capacitor as to apply high-frequency
the said feeding means coupled to the line in the
voltage thereto, at least one side of said line con
sisting of a length of at least one of said wires 15 part thereof directly adjacent to the said point
whereby to obtain a large rise in voltage between
on the entering side of said rolls and conductive
said feeding means and the two sides of the line
1y related to the portion of said one of said wires
at the rolls.
in the/nip of the rolls, means electrically con
7. The apparatus de?ned by claim 1 having
necting the two sides of the line together at a
said feeding means constituted by a coupling loop
point in said length distant from said rolls by
nearly one quarter of the Wave-length corre
sponding to said frequency, and means between
said point and the rolls for feeding said high
frequency electric energy into said line.
2. The apparatus de?ned by claim 1 having
the two sides of the said line constituted by two
spacially separated groups of the said wires.
3. The apparatus de?ned by claim 1 having
the two sides of the said line constituted by two
spacially separated groups of the said wires all
lying in one and the same plane.
4. The apparatus de?ned by claim 1 having
the two sides of the said line constituted by two
spacially separated groups of the said Wires, the
adjacent the line and the said point and an os
cillator electrically connected to said loop.
8. The apparatus de?ned by claim 1 having
said. feeding means constituted by an oscillator,
an electrically conductive connection from said
oscillator to the line at said point and another
electrically conductive connection from said os
oillator to a point in one side of said line located
a distance from said point which is only a minor
proportion of the length from said point to the
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