Improvements in and relating to the Manufacture of Armored Electric Cables.
Year: 1899

page_text: Date of Application (in United Kingdom), 17th Apr., 1899
Complete Specification Left, 17th Apr., 1899-Accepted, 19th Aug., 1899
Improvements in and relating to the Manufacture of Armored
Electric Cables.
I, EDWIN TRUMAN GREENFIELD, of No. 527, West 34th Street, New York,
United States of America, Electrician, 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 :-
-
This invention has reference to the manufacture of armored electric cables,
by continuously forcing strips of metal into a suitably shaped die through which
the cable to be armored is caused to pass longitudinally while being revolved,
whereby the said strips of metal are spirally formed and at the same time applied
to the cable.
In carrying out my invention I employ a machine comprising three main
groups of contrivances iz:-one for feeding the unarmored cable through the
machine; another for spirally forming and applying the armor to the cable;
and, another for reeling or winding up the armored cable. These groups of
contrivances are so combined as to operate to produce a complete armored cable
wound upon a reel or otherwise prepared for transport, and are furthermore
so detachably connected together as to permit one group to be removed without
necessarily disturbing the function of the others.
According to my invention the speed at which the armor is manufactured and
applied regulates, on the one hand, the speed at which the unarmored cable
is delivered to the armoring device, and regulates on the other hand the speed
of revolution of the reel upon which the armored cable is wound, so that the
said machine is self regulating in its action.
In order that the said invention may be fully understood and readily carried
into effect I will proceed to describe the same with reference to the accompanying
drawings in which:-
:-
Figure 1 is a longitudinal elevation of the entire machine, with the exception
of the delivery reels and the guides for the metallic armor strips, which are
omitted for the sake of clearness.
Figure 2 is an enlarged detail view of the automatic regulating device by
which the speed of the reel carrying the unarmored cable is regulated.

page_text: and 11). This trough J is omitted in Figure 5 for the sake of clearness, it
As
being situated immediately beneath the forming and feeding rolls K' K³.
will be seen on reference to Figures 10 and 12, the strip e enters the trough J
at a higher plane than the strip e', but passes diagonally downward toward the
plane of the strip e¹; the strips may also converge as they pass forward
(Figure 11). As the strip e passes along through the box J, it is met by the
forming and feeding rolls K³K, the upper one K³ of which has a grooved
periphery (Figure 13) and the lower one K* a correspondingly curved periphery,
so that the rolls K³K form, respectively the female and male members of a
roller-die by which the stripe is shaped into a U-form in cross-section, the con-
vexity being directed upwards. In like manner the strip el is given a U-shape
or form by the rolls K' K², the convexity of the strip e¹, being however directed
downwards. As the strips are thus shaped or formed by the rolls, teeth 11 upon
the periphery of the upper roll K¹ and upon the periphery of the lower roll K+,
make a series of indentations or breaks upon the concave side of each of the
strips (see Figure 7) these breaks serving to facilitate the winding of the said
strips in spirals, as will be hereinafter described.
The two series of forming and feeding rolls K' K² and K³ K are operated from
the main motor shaft O¹ of the machine, by a train of gear wheels of which 03, 0*;
K³, K, (Figure 5), form part, the remainder of the train being situated beneath
these gears (and not shown). The said gear wheels operate to draw the strips e, et
from their reels, and after shaping them as described, drive or force them through
the trough J to the armor forming box L. This box contains, or has rigidly
secured to it, an interiorly screw-threaded two-part die M, provided, on one side,
with holes M' M² (Figures 7 and 8), into which the guides ;;' (Figure 11) of
the trough J project, so as to leave openings through which the strips e, el pass.
One half of this two-part die is provided with dowel pins and the other with
dowel holes, as clearly illustrated in Figure 7.
As will be seen by referring to Figure 8, the hole M¹ through which the stripe
passes is upon the same plane as the hole M² which is provided for strip e¹. Both
strips enter the screw-threaded die M at an angle to its axis, and in line with
the screw grooves mm (Figures 7 and 8) which are formed in the longitudinal
bore of the die. As the strips ce are forced into these screw-grooves by the
friction of the pairs of rolls KK2 and K³, K, they are formed into long spiral
tubes. The strip e', which has its convex side outward, fits into the hollows or
grooves m, m, and the strip e, which has its concave or hollow side outward, fits
over the projections or ribs m¹ m², as shown in Figure 7.
The electric cable A, being fed from its reel B, enters the longitudinal bore
of the die M, as shown by the dotted lines in Figures 5 and 7, and passes to
the right, the strips e, e¹, being formed into a close spiral covering or armor
thereon, by reason of the fact that as said strips are drawn or fed continuously,
through the agency of the said rolls K' K², KK, the interior surface of the die
constitutes a bending surface, whereby said strips are bent or formed into
spirals which overlap or break joint with each other. The strip e which has
its cross-sectional curvature outward occupies a position outside of the strip e,
which has its cross-sectional curvature inward. Thus the downwardly projecting
edges of strip e¹, when wound on the cable A, project into the concavity or groove
upon the upper surface of strip e, and the upturned edges of said strip e interlock
with the groove of the adjacent strip e¹, so making a complete metallic armor
or covering D for the cable A (see Figure 7) which is flexible to the limit of
movement of the engaging strips eel within each other.
Since the power expended in bending the grooved strips e e¹ is sufficient to
generate considerable heat, even after the application of a lubricant by the
saturated pade, I provide, below and partly surrounding the lower part of
the box L, a reservoir N (Figure 11) to which a continuous supply of cold
water is forced through the pipe n, an outlet being provided for the water through
the pipe n¹.

page_text: Assuming the rate of revolution of frame F to be less than that of gear
wheels o7 08, it is evident that the finger o⁰ of the metal band which is carried
by the gear wheel 8 will, in a few revolutions, engage with the point or plate o¹
(see Figure 14). Now, the frame F carries a magnet c, which, as shown in
Figure 14, is connected in series with the armature Q' of the auxiliary motor Q.
This motor is normally idle, and merely runs as a dynamo actuated by the shaft G¹
of the revolving frame F through the gear wheels H, H' and the shaft H³. A
solenoid T is connected to the contact plate o12 (Figure 14) and through a brush o¹³
to the metal band o, electrical connection being also established with the
starting switch U of the motor. When, therefore, the metal finger o⁰ makes
contact with the plate o12, an electric circuit is established from o¹0, through the
solenoid back to the plate 12, and the solenoid then acts, by raising the metal
plate t, to start the motor Q. The current from armature Q₁ of said motor then
energizes the magnet c, which, in turn attracts the free end 61 of a pawl b, and
thus releases the tooth of a ratchet-wheel g with which said pawl engages (see
Figures 3, 6, and 14). The auxiliary motor Q, upon the completion of the
electric circuit and the withdrawal of the pawl b, is free to rotate the frame F,
through the shaft H2 and gear wheels HH. The power of this auxiliary motor Q
soon drives the frame F at a greater speed than that of the gear wheel 08 and
enables it to compensate for the amount of its previous lag. As soon as this is
done, the contact plate o12 moves out of engagement with the finger 010 and the
circuit is broken. The pawl is then no longer attracted by the magnet c and is
caused by its spring 2 to re-engage with the ratchet gl. The frame F then
again revolves at its normal speed.
In practice, the engagement of the finger 10 and the plate o2 is momentary,
the circuit being broken almost instantaneously by the additional impulse given
to the frame F, under the action of the auxiliary motor Q, which carries the
contact plate o2 forward and out of engagement with the finger o¹0. The action
of the magnet e likewise is practically instantaneous, so that the pawl b falls
into engagement with the ratchet tooth next to that from which it had just been
raised by the action of the magnet.
By this almost instantaneous throwing of the auxiliary motor Q into and out
of gear with the frame F, any difference between the speed of revolution of this
frame (and consequently of the unarmored cable A) and that of the armored
cable, is equalized before any injurious torque between the cable A and the
armor is caused at L.
While it would be possible so to proportion the various gearings that the
frame F would run, normally, at exactly the same speed of revolution as the
armored cable, yet, in practice, the calculations and tests that would be necessary
for the requisite accuracy could be obtained, and the frequency with which errors
of calculation or inequalities of wear would occur, would be found sufficient to
cause slightly different speeds (highly injurious in their results) which would
make the attainment of the desired synchronism of movement difficult.
It is manifest that, as the pawl b engages practically instantaneously, with the
ratchet-tooth next to that from which it has just been released by the attraction
of the magnet c, the greatest difference between the position of any one point
(as the contact o12) on the collar o" and the corresponding point (as the finger 010)
on the band o will be the distance between any two teeth upon the ratchet g¹;
these teeth are so spaced that the distance is negligible.
While I have described in detail one means of regulating the speed of my
cable feeding apparatus so that it will be equalized with the rate of speed of the
armor forming mechanism, I do not intend to limit myself to the precise con-
struction shown, since many other equivalent forms may be constructed which
will come within the spirit of my invention.
The strips ce may be grooved by a separate operation, before being fed to
my bending device or armor forming die M, in which case the forming and
indenting rolls may be omitted and any suitable feeding devices substituted for