LUBRICATED PLASTIC IMPREGNATED ARAMID FIBER ROPE

CABLE PLASTIQUE, IMPREGNE, DE FIBRES D'ARAMIDE LUBRIFIEES

English Abstract

Case 5649
LUBRICATED PLASTIC IMPREGNATED
ARAMID FIBER ROPE
Abstract of the Disclosure
An aramid fiber rope having a central core surrounded
with aramid fiber rope strands. The core and the aramid
strands are coated with a heavy viscous lubricant prior
to winding the strands into rope. The lubricated rope
is then impregnated and surrounded with a plastic
material to entrap the lubricant in the core and the
strands.
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Claims

Case 5649
THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A rope comprising a central core, said central
core being comprised of a plurality of aramid fiber strands
laid around a central core strand, said strands being
lubricated with a heavy, viscous lubricant, a plurality of
aramid fiber outer strands laid around said central core,
said strands being equally spaced from each other and
lubricated with a heavy, viscous lubricant,
and a flexible thermoplastic material filling the
space between said central core and said outer strands and
between adjacent outer strands to retain the lubricant in
said strands and to keep said outer strands in a fixed
position relative to each other,
said thermoplastic material extending outwardly to
the outer periphery of said outer strands.
2. A method of producing an aramid fiber rope com-
prising the steps of:
winding aramid yarn into strands, coating said
strands with a heavy, viscous lubricant and winding a
plurality of said strands around a central core strand to
form a central core,
providing a plurality of aramid fiber rope strands
and coating said strands with a heavy, viscous lubricant,
and winding said strands so that said strands are equally
spaced around said central core to form a multi-strand rope
comprising a central core and outer strands, and impregnating
the rope with a thermoplastic material such that the thermo-
plastic material fills the spaces between said central core
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and said outer strands and between adjacent outer strands to
retain the lubricant in the strands and to keep said outer
strands in a fixed position relative to each other, said
thermoplastic material extending outwardly to the outer
periphery of said outer rope strands.
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Description

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3/10/~1
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Field of the Invention
This invention generally relates to a synthetic fiber
rope in a wire rope construction, and particularly to a
plastic impregnated, lubricated synthetic fiber rope in a
wire rope construction and a method for producing the same.
Background of the Invention
The family of aromatic polycarbonamide fibers possess-
ing extremely high strength, high modulus and low elongation
are commercially available from the E. I. DuPont de Nemours
& Co. under the trademark "Kevlar" and are generally
referred to as aramid fibers. Such aramid polymers are
described in U.S. Patents 3,652,510, 3,673,1~3 and 3,699,085.
There are many known methods of lubricating aramid
fibers such as with various types of waxes and resins for
the purpose of improving fatigue life, reducing yarn
contact stresses and inhibiting fretting. However, it has
been found that prior art lubricated aramid fiber yarns
have not always performed satisfactorily, especially in
standard wire rope constructions.
Presently known methods or stranding and closing an
aramid fiber rope of wire rope type construction produced
a rather unstable rope, in that the aramid fiber strands
do not retain a "memory" of the preforming step. That is,
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Case 5549
!%
the strands do not conform to the helix or lay direction
of the rope and, therefore, have a tendency to ~mlay into
a stable parallel lay condition. Often this imbalance
tends to develop "bird-caging" of the outer strands,
! 5 especially in multi-strand ropes.
;
Summary of the Invention
The present invention provides a method for producing
a heavily lubricated aramid fiber rope which is impregnated
with a load-bearing plastic such that the viscous lubricant
is entrapped in the strands and core. The outside diameter
of the plastic impregnated rope conforms to the outside
diameter of the external aramid ~iber strands. The aramid
fiber rope produced by this method has a smooth outer
periphery with increased bearing area without increased
rope diameter.
The object of the present invention is to provide a
lubricated, plastic impregnated aramid fiber rope and a
method ~or making the same.
The plastic impregnation o the aramid fiber rope
of the present invention is accomplished by pressurized
e~trusion of a flexible thermo~lastic into the interstices
of the rope.
Impregn~tion of a lubricated aramid Eiber rope wit~
?lastic in accordance with che present invention inhibits
entrance of :Eorei~n abrasive particles into the rope,
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- Case 5649
prolongs the lubricant's lie inside the rope and in
addition, forms a matrix that both supports and locks the
individual strands in position relative to each other.
Another advantag~ is a reduction in fiber and yarn
building block notching and internal friction because
the loads placed on rope are shared substantially equally
by the spaced internal aramid fiber building blocks.
Furthermore, a lubricated aramid fiber building bloc~
rope, impregnated with plastic while holding the outer
strands spaced from each other, will have extremely good
resistance to fatigue and an increased ultimate breaking
strength because of a reduction in internal fiber building
block contact, all while maintaining flexibility.
Brief DescriPtion of the Drawin~
The drawing is a cross section view of the plastic
- 15 impregnated aramid fiber rope.
3escription of the Preferred Embodiment
The present invention utilizes conventional wire
rope constructions, such as 10, using aramid fibers 11
wherein individual aramid fiber yarn building blocks 12
are wound into strands 14, and a plurality of strands
are formed abou~ a core 16 which is illustrated as formed
of a plurality of strands 18. ~he core 16 could be of a
single strand. It should be understood that the core L6
may be formed of natural fiber material such as: sisal

5649
3/19/81
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or hemp; synthetic materials such as polyolefins, polyamides,
or polyvinylchlorides; or metal such as steel or aluminum.
The particular rope shown in the drawing is given by
way of example of the preferred embodiment. It should be
understood that the plastic impregnating process to be
described hereinafter may be applied to any of the various
rope configurations utilizing cores of aramid or natural
fiber, synthetics or metal. During fabrication of an
aramid fiber rope, a viscous lubricant 19 is pumped around
each aramid fiber yarn building block 12 as it is formed
into strands. Conventional lubricants suitable for this
purpose are certain silicones and waxes.
A flexible thermoplastic 22 is extruded, under pres-
sures sometimes as high as 4~000 PSI into the interstices
of the rope or the rope is immersed in a thermoset plastic
and subsequently cured, completely filling the interstices
down to the outer strands of the core, but not extending
outwardly beyond the outer diametrical limits of the rope
10 as indicated at 23. The thermoplastic can be any of
those capable of being extruded, such as polypropylene,
polyurethane, polyethylene, nylon or tetrafluoroethylene.
The thermoset plastics may be any that will penetrate
the interstices, conform to the required in-filling of
strand valleys, and have a sufficiently low curing tempera-
ture such as some plastisol vinyl plastics.