Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2~3~ Case 5984
04/14/89
EJB:cmg
WIRE F~OPE WITH COMPACTED P~AST~C FILLER E~E5MENTS
Backqround of the Invention
The present invention relates generally to wire ropes
and, more particularly to a wire rope having compacted plastic
filler elements.
wire rope can have several different configurations, two
of the most common being a rope having a fiber core surrounded
by a plurality of outer strands each comprised of several
metal wires and a rope having a core comprised of a plurality
of metal wires surrounded by outer strands also comprising a
plurality of metal wires. A wire rope with a metal wire core
is frequently referred to as having an independent wire rope
core.
It is known to infill wire rope with a variety of
plastics, thermoplastics, or elastomers as such materials
reduce contact stress between strands, improve strand load
sharing, seal in lubricant within the strands and seal out
corrosive and abrasive materials. The thermoplastic
impregnation of wire rope is disclosed in U.S. eatent
3,824,777. It is also known from U.S. Patent 4,509,319 to
provide precisely shaped plastic or thermoplastic ~iller
elements into a wire rope during final forming. Such filler
elements are chosen to conform to the shape of the interstices
between the independent wire rope core and the outer strands
and also between outer strands such that upon final closing of
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the rope, the preformed filler elements conform in cross
section to such interstices and provide seating for the outer
strands around the core and also adjacent to each other.
One possible disadvantage in the plastic impregnation of
a completed wire rope or the laying of precisely shaped
elements in the interstices of a wire rope at closing is that
contact may occur after such processing between the core and
the outer strands and between adjacent outer strands. Such
contact is not desirable as it can lead to notching of
individual wires and eventual rope failure.
Another method of providing a thermoplastic impregnated
wire rope is to coat a wire rope core with a jacket of
plastic, thermoplastic, or elastomer and then compress outer
strands into the jacket as shown in U.S. Patent 4,120,145.
This method reguires considerable radial pressure and is
difficult to control such that an even filling with plastic
material is formed between the core and the outer strands and
between the adjacent outer strands.
~mary of the Invention
Accordingly, it is an object of the present invention to
provide a wire rope with plastic filler elements that can be
compacted to form a uniform plastic spacing element in the
wire rope. A wire rope is provided which comprises a core
which is usually an independent wire rope core. A plurality
of plastic, thermoplastic or elastomer elements, collectively
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referred to as plastic filler elements, are laid in a spirally
twisted relationship about the core, usually simultaneously
with the closing of outer wire strands about the core. The
resultant wire rope is compacted by die forming to final size
usually in a single operation directly downstream of the
closing die. The plastic elements may be circular in cross
section or of some other selected shape, but in the compacting
operation the plastic elements are compressed and squeezed to
flow together to fill the interstices between the core and the
outer strands of the wire rope. Depending on the relative
size of the plastic elements and the desired final wire rope
configuration, the plastic formed by the squeezing of the
plastic filler elements may extend partially or totally to the
outer rope diameter. The resultant rope has a predetermined
or pre-selected wall thickness of plastic between the core and
the outer strands. If desired, the plastic elements may be so
selected such that a pre-selected thickness of plastic also
flows between the outer rope strands such that the outer
strands are equally spaced from each other. Due to the high
compressive forces used to compact and position the outer
strand~, no further compaction will take place during the
service life of the rope. Outer strand to core contact as
well as outer strand to adjacent outer strand contact will be
negligible or virtually non-existent thereby eliminating one
of the major causes of internal rope failure. The fatigue
life of the core will also be extended because the core is
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surrounded by plastic material thereby insuring that
appropriate lubricant is retained in the core.
The plastic filler elements may be of various cross
section shapes, and such shapes include a round cross section
forming a rod or wirelike plastic filler element, a
combination of a rod with rectangular extension therefrom, a
plain rectangular shape element, a triangular shape or some
combination thereof. The initial shape o~ the plastic filler
element is a consideration, but of greater concern is the
overall volume of plastic material in the filler elements in
relation to the final desired wire rope configuration. In the
final wire rope configuration, the volume of the inter~tices
in relation to the volume of the plastic filler elements will
dictate the degree of compression o~ such plastic filler
elements and the resulting flow of the plastic filler elements
to form a composite plastic layer. The plastic layer forms a
spacing between the core and the outer strands of uniform
predetermined dimensions. Further, the plastic filler
elements can be pre-selected to flow outwardly between the
outer strands to a desired degree. If only minor degree of
outward flowing is desired, the plastic layer would only form
a seat for the outer strands. Bowevex, if a greater degree of
outward flowing of the plastic layer is desired, the plastic
layer can flow outwardly to form uniform spacing between
adjacent outer strands and extend partially or just to the
outer diameter of the outer strands themselves. In such case
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where the plastic layer extends to the outer diameter of the
wire rope, the plastic layer would significantly seal the
lubricant in the outer strands and also prevent the ingress of
corrosive or abrasive materials into the outer strands. This
is in addition to the plastic layer completely sealing the
lubricant in the core.
Brief Descri~tion of the Drawin~s
In the drawings,
Figure 1 is a sectional view of a wire rope in accordance
with a first emhodiment of the present invention prior to
compaction;
Figure 2 is a sectional view of the wire rope of Figure 1
after compaction;
Figure 3 is a sectional view of the wire rope of Figure 2
after further compaction to a swaged configuration;
Figure 4 is a sectional view of the wire rope in
accordance with a second embodiment of the present invention
prior to compaction;
Figure 5 is a sectional view of the wire rope of Figu.re 4
after compaction;
Figure 6 is a sectional view of the wire rope in
accordance with a third embodiment of the present invention
including flattened outer strands prior to compaction;
Figure 7 is a sectional view of the wire rope of Figure 6
after compaction, and
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Figure 8 is a sectional view of various plastic filler
elements.
Detailed Descri~tion of the Preferred Embodiments
~ eferring now to Figures 1-3 of the drawings, a wire rope
in accordance with a first embodiment of the present invention
is shown in cross section. The rope comprises an independent
wire rope core 10 which is comprised of individual wires.
Core 10 is surrounded by plastic filler elements 12 which are
twisted about core lO in a spiral fashion. Plastic filler
elements 12 may be comprised of a suitable plastic,
thermoplastic or elastomer as desired. Outer strands 14 are
comprised of individual wires, and outer strands 14 are wound
about core 10 and plastic filler elements 12 in a manner such
that each of outer strands 14 is in contact with two of
plastic filler elements 12. The number of outer strands 1~
accordingly equals the number of plastic filler elements 12.
The wire rope shown in Figure 1 is shown prior to any
compacting of outer strands 14 into plastic filler
elements 12. Both core 10 and outer strands 14 are usually
lubricated.
In Figure 2, the same wire rope shown in Figure 1 is
shown after compacting of outer strands 14 inwardly into
plastic filler elements 12. Such compacting is usually done
by drawing the rope through a roller compactor or a die such
that outer strands 14 compress and squeeze plastic filler
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elements 12 to form a homogenous single plastic layer 16. The
degree of plastic extension will depend on the pre-selected
diameter of plastic filler elements 12, the desired final rope
diameter as well as the diameter Or core 10 and outer
strands 14. Plastic layer 16 is ssen to form a spacing
between core lO and outer strands 14 which can be of a
predetermined and uniform dimension. Plastic layer 16 is also
seen to extend outwardly to form a spacing between adjacent
outer strands 14 such that outer strands 14 are seated in
depressions formed in plastic layer 16. Plastic layer 16 also
act~ to keep outer strands 14 at predetermined and desired
spacing from each other to avoid contact between adjacent
outer strands. such uniform spacing between core 10 and outer
strands l4 as well as between adjacent outer strands 14
assures increased wear life for the wire rope due to
prevention of contact between component core and outer strands
and also due to better equalization of load sharing between
outer strands 14 and core strand 10.
Referring now to Figure 3, the wire rope of Figure 2 is
~0 shown after further compacting or swaging whereby outer
strands 14 are flattened on their outer periphery and forced
further inwardly toward core 10. Such further compaction of
the wire rope causes plastic layer 18 to extend outwardly
further between outer strands 14 such that it approaches the
final outer diameter of the outer ro~e. Such further
compaction of the wire rope is desirable in certain
applications and provides a lower diameter final wire rope.
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The plastic layer 18 extending outwardly to near the final
diameter of the rope, provides further seating for outer
strands 14 and assures their even spacing throughout the rope
life. It also assures to a greater degree the retention of
lubricant not only within core 10 but also within outer
strands 14.
Referring now to Figures 4 and 5, a wire rope in
accordance with the second embodiment of the present invention
is shown. In Figure 4, core 20 is comprised of individual
wires and is surrounded by plastic iller elements 22 which
are wound about core 20 in a spiral manner. Outer strands 24
are also comprised of individual wires and are wound about
plastic filler elements 22 in a manner such that each of outer
strands 24 contacts two of plastic filler elements 22. Both
core 20 and outer strands 24 are usually lubricated. Plastic
flller elements 22 are shown as comprising circular elements
in cross sectlon and in essence comprlse round wires of
plastic, thermoplastic, or elastomer. Plastic filler
elements 22 and outer strands 24 are usually wound about
core 20 in a single closing operation. The wire rope shown in
Figure 4 is shown prior to compaction. Plastic filler
elements 22 are of a larger diameter than plastic filler
elements 12 in Figure 1. Accordingly, as shown in Figure 5,
during compaction when outer strands 24 are die compacted to
move inwardly to squeeze plastic filler elements 22, plastic
filler elements 22 combine to form a composite plastic
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layer 26 which expands outwardly to near the outer diameter of
outer strands 24. A lesser degree of compaction of outer
strands 24 than the compaction provided outer strands 14 in
Figure 2 results in a greater extent of plastic layer 26
extending outwardly due to the greater diameter of plastic
filler elements 22 in relation to the diameter of core 20 and
outer strands 24. Further, the design or pre-selected final
rope configuration shown in Figure S is planned to have
interstices between core 20 and outer strands 24 and also
1~ between outer strands 24 such that plastic filler elements 22
are of a sufficient volume to fill such interstices to the
point near the outer diameter of outer strands 24. Plastic
layer 26 provides the usual already described functions of
retaining lubricant in core 20 and also within outer
strands 24. Further plastic layer 26 provides a uniform,
pre-selected spacing between core 20 and outer strands 24 and
also between adjacent outer strands 24. ~he usual desirable
properties of such un~form spaclng leading to greater rope
llfe are provided by such plastic layer 26.
Referring now to Figure 6 and 7, wire rope in accordance
with a further embodiment of the present invention is shown.
Referring to ~igure 6, a core 30 is comprised of individual
wir~s. Plastic filler elements 32 are wound about core 30 in
a spiral manner. Plastic filler elements 32 include a head
portion which is generally tubular as well as an extended
somewhat rectangular body portion 33 extending radially
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outwardly ~rom the tubular head portion. Outer strands 34 are
also comprised of individual wires and are wound about and
between plastic filler elements 32. The view of the wire rope
shown in Figure 6 is prior to compaction of outer strands 34;
however, outer strands 34 are of a flattened, profiled cross
section.
Referring now to Figure 7, the wire rope of Figure 6 is
shown after outer strands 34 have been compacted inwardly
toward core 30. Such compaction causes the squeezing of
plastic filler elements 32 such that the plastic forms a
homogenous plastic layer 36 which extends around core 30 and
between adjacent outer strands 34 to a point just less than
the outer diameter of outer strands 34. The shape and volume
of plastic filler elements 32 is chosen in relation to the
desired final rope configuration such that the interstices or
spaces between core 30 and outer strands 34 and also between
outer strands 34 are such that the volume of plastic filler
elements 32 will fill such spaces in the final rope
conf'iguration as shown in Figure 7. The spacing between
core 30 and outer strands and also between adjacent outer
strands 34 is predetermined and uniform to provide the usual
improvements in wire rope perform~nce. Further, plastic
layer 36 acts to retain lubricant within core 30.
Referring now to Figure 8, various cross sections of
plastic filler elements are shown at "A", "B", "C", "D", and
"E". The initial cross sectional configuration of plastic
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filler elements can be chosen such as at "A" and "C" to
include depressions to act as seats against the core and
between adjacent outer strands, if desired during the rope
forming operation. However, it is not necessary that plastic
filler elements include such seating properties, for example,
plastic filler elements, "B", "Dn, and "E" do not provide such
depressions for core and outer strand seating. ~owever, all
the plastic filler element configurations are adaptable to
acceptable performance during outer strand compaction such
that, with appropriate selection of plastic filler element
volume veesus the final volume of interstices in the wire
rope, that the plastic filler elements will combine to form a
uniform, homogenous plastic layer extending around the wire
rope core and to the desired degree outwardly between outer
strands. The important point is that the resulting plastic
layer will be uniform and will provide uniform spacing betwean
the core and the outer strands and between adjacent outer
strands to provide the desired improved wire rope performance.
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