U.S. patent application number 10/464404 was filed with the patent office on 2004-01-15 for plastic impregnated wire rope with internal separating bands.
Invention is credited to Misrachi, Joseph, Payant, Olivier, Quirion, Vincent.
Application Number | 20040006963 10/464404 |
Document ID | / |
Family ID | 30005547 |
Filed Date | 2004-01-15 |
United States Patent
Application |
20040006963 |
Kind Code |
A1 |
Misrachi, Joseph ; et
al. |
January 15, 2004 |
Plastic impregnated wire rope with internal separating bands
Abstract
A plastic impregnated wire rope is provided with plastic bands
between its core and its outer strands so as to prevent contact
between the wires of the core and those of the outer strands during
flexing of the rope. This produces a substantial increase in the
life of the rope. The method for manufacturing such rope involves
wrapping plastic bands on the core just prior to laying outer
strands on the core and on top of the plastic bands. Thereafter,
the so formed rope is impregnated with molten plastic, which is
then allowed to solidify.
Inventors: |
Misrachi, Joseph; (Montreal,
CA) ; Payant, Olivier; (Sainte-Therese, CA) ;
Quirion, Vincent; (Chateauguay, CA) |
Correspondence
Address: |
GEORGE J. PRIMAK
13480 HUNTINGTON
PIERREFONDS
QC
H8Z 1G2
CA
|
Family ID: |
30005547 |
Appl. No.: |
10/464404 |
Filed: |
June 19, 2003 |
Current U.S.
Class: |
57/223 ;
57/7 |
Current CPC
Class: |
D07B 2201/2019 20130101;
D07B 1/162 20130101; D07B 2201/1036 20130101; D07B 1/144 20130101;
D07B 1/167 20130101; D07B 2201/2074 20130101; D07B 2201/2037
20130101; D07B 7/145 20130101; D07B 2207/4027 20130101; D07B
2201/102 20130101 |
Class at
Publication: |
57/223 ;
57/7 |
International
Class: |
D02G 003/36; D07B
001/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 12, 2002 |
CA |
2,393,220 |
Claims
1. A plastic impregnated wire rope having a wire rope core and
outer strands wound around said core, characterized in that said
wire rope is provided with plastic bands between the core and the
outer strands, said bands having such size and shape as to
essentially prevent contact between the wires of the core and those
of the outer strands during operation of the rope, but without
substantially impeding the flow of molten plastic into and within
the wire rope during plastic impregnation of said wire rope.
2. A plastic impregnated wire rope according to claim 1, in which
the plastic bands are made of a thermoplastic material.
3. A plastic impregnated wire rope according to claim 2, in which
the thermoplastic material of the bands is a thermoplastic
elastomer.
4. A plastic impregnated wire rope according to claim 3, in which
the thermoplastic elastomer is polypropylene.
5. A plastic impregnated wire rope according to claim 1, in which
the plastic bands have an arcuate face in contact with the outer
strands.
6. A plastic impregnated wire rope according to claim 1, which
comprises full plastic impregnation of said wire rope.
7. A plastic impregnated wire rope according to claim 1, which
comprises partial plastic impregnation of said wire rope.
8. Method of producing a plastic impregnated wire rope which
comprises: (a) forming a wire rope core and moving it towards a
closing station; (b) forming outer strands for the wire rope and
moving them towards the closing station; (c) winding the outer
strands around the core at the closing station; (d) wrapping
plastic bands of predetermined size and shape over the wire rope
core at the entrance to the closing station, prior to winding of
the outer strands around said core, said plastic bands being laid
on the core so as to provide controlled plastic separation between
the outer strands and the core, while leaving sufficient spacing
between the bands to allow flow of molten plastic therethrough; and
(e) after closing the wire rope with the plastic bands laid between
the outer strands and the core, impregnating said wire rope with a
molten plastic material and subsequently allowing said plastic
material to solidify.
9. Method according to claim 8, wherein wrapping of the plastic
bands over the wire rope core is done with the help of a hollow
frusto-conical device mounted and rotating around the core at the
entrance of the closing station, said device having slots on its
internal surface for guiding the plastic bands towards the core and
allowing them to be laid on the core in a predetermined manner.
10. Method according to claim 9, wherein the bands are laid on the
core so as to follow the same lay as the outer strands.
11. Method according to claim 8, wherein the wire rope core being
formed is an independent wire rope core.
12. Method according to claim 8, wherein the wire rope core being
formed is a lubricated core.
13. Method according to claim 8, wherein the outer strands being
formed are lubricated strands.
14. Method according to claim 8, wherein eight outer strands are
used together with eight plastic bands on which said outer strands
are positioned.
15. Method according to claim 8, wherein plastic impregnation of
the wire rope is carried out as a separate operation after forming
the non-impregnated rope with plastic bands laid between the core
and the outer strands.
Description
FIELD OF THE INVENTION
[0001] This invention generally relates to a plastic impregnated
wire rope. More specifically, it relates to a wire rope that, in
addition to plastic impregnation, has internal separating bands
positioned between the outer strands of the rope and the core
strands to prevent direct contact between these strands during
flexing of the rope and thereby extend the life of the rope. The
invention also relates to the method of manufacturing such wire
rope.
BACKGROUND OF THE INVENTION
[0002] Plastic impregnated wire ropes are well known in the art. An
example of such wire rope is disclosed in U.S. Pat. No. 4,120,145
by Chiappetta et al. where a wire rope is impregnated with a
plastic material between a lubricated core and lubricated outer
strands of the rope. However, direct contact between the wires of
the outer strands of the core and those of the outer strands of the
rope will still occur during flexing of the rope under working
conditions and this contact prematurely damages the wires and
shortens the life of the rope.
[0003] Another example of a fully plastic impregnated or plastic
filled wire rope is disclosed in U.S. Pat. No. 4,667,462 belonging
to the present applicant. In this case, the plastic material fills
essentially completely all the interstices between the strands and
the individual wires of the rope. Again, however, during operation
of the rope, contact between the wires of the outer strands of the
rope and the wires of the outer strands of the core is not
prevented by such full plastic impregnation, leading to degradation
and eventual premature failure of the rope.
[0004] Therefore, there is a need for an improved plastic
impregnated rope in which contact between the wires of the outer
strands of the rope and the wires of the outer strands of the
rope's core would be essentially prevented.
[0005] There are prior art patents that recommend placing a
protective layer such as a plastic ridge or protective inserts such
as plastic strips to prevent contact between the wires of the outer
strands and those of the core of a wire rope. Canadian Patent No.
648,788 of Alfred Dietz discloses the ridge construction and U.S.
Pat. No. 4,166,355 discloses the construction using non-metallic
inserts. In both cases, however, the gaps between the outer strands
of the wire rope and the strands of the core are completely blocked
by such devices and thus no plastic impregnation of the rope could
take place since molten plastic would not be able to flow through
such ridge or such protective inserts or strips.
SUMMARY OF THE INVENTION
[0006] The present invention obviates the above mentioned
disadvantages and provides a plastic impregnated wire rope having a
wire rope core and outer strands wound around said core, which is
characterized in that said wire rope is provided with plastic bands
between the core and the outer strands, said bands having such size
and shape as to essentially prevent contact between the wires of
the core and those of the outer strands during operation of the
rope, but without substantially impeding the flow of molten plastic
into and within the wire rope during plastic impregnation of said
wire rope. The core of such wire rope is usually an IWRC
(independent wire rope core). The resulting wire rope is a plastic
impregnated rope with a controlled plastic separation between the
outer rope strands and the outer core strands.
[0007] The plastic bands may be made of any suitable material that
would be durable and prevent contact between the wires of the core
and the outer strands. Preferred materials are thermoplastics and
particularly thermoplastic elastomers of which the preferred one is
polypropylene. Other materials, such as high density polyethylene,
nylon, etc., can also be used and even materials such as textile
strips may be suitable if properly made to prevent contact between
the wires during flexing of the wire rope when it is being
operated.
[0008] The bands may be of various shapes and sizes or thicknesses
depending on the size and geometry of the rope. Normally, there
will be as many bands as there are outer strands in the rope.
Preferably, the bands have arcuate faces in contact with the outer
strands, essentially matching the contour of the outer strands.
[0009] The wire rope provided with the plastic bands as described
above may be fully impregnated or filled with a plastic material or
only partially impregnated. In this latter case, the core may be
not fully impregnated, but mostly left as a lubricated core, and/or
the impregnation may not go all the way to the outer periphery of
the rope.
[0010] The method of producing the plastic impregnated rope of the
present invention essentially comprises:
[0011] (a) forming a wire rope core and moving it towards a closing
station;
[0012] (b) forming outer strands for the wire rope and moving them
towards the closing station;
[0013] (c) winding the outer strands around the core at the closing
station;
[0014] (d) wrapping plastic bands of predetermined size and shape
over the wire rope core at the entrance to the closing station,
prior to winding of the outer strands around said core, said
plastic bands being laid on the core so as to provide controlled
plastic separation between the outer strands and the core while
leaving sufficient spacing between the bands to allow flow of
molten plastic therethrough; and
[0015] (e) after closing the wire rope with the plastic bands
positioned between the outer strands and the core, impregnating
said wire rope with a molten plastic material and subsequently
allowing said plastic material to solidify.
[0016] The wire rope core is normally an independent wire rope core
that is lubricated and formed with the help of a preforming head as
is known in the art. The outer strands are also normally lubricated
and made in a conventional manner. The closing station may consist
of closing dies, again as is known in the art. The plastic bands
may be guided towards the closing station and laid on the core just
as the strands are being laid and closed on the core over said
bands, to form the rope. To facilitate laying of the bands on the
core in a proper manner, a hollow frusto-conical device may be
mounted around the core, near the entrance to the closing dies,
which device is connected to the performing head and rotates
therewith. The device has slots on its internal surface for guiding
the plastic bands towards the core and allowing them to be laid on
the core in a predetermined manner, usually so as to follow the
same lay as the outer strands. In this manner, when the closing of
the rope has been done, the outer strands will rest on the plastic
bands and will not be in contact with the core below them, the
bands insuring a constant, controlled plastic separation between
the outer strands of the rope and those of the core.
[0017] Once the rope is closed as described above, it is then
impregnated with plastic material, for example by running it
through an extrusion head as disclosed, for instance, in U.S. Pat.
No. 4,609,515 which belongs to the present applicant, and the
disclosure of which is incorporated hereinto by reference. Also, in
lieu of a full filling of the rope as disclosed in the above
patent, one may impregnate the rope only partially so that, for
example, the core would not be fully impregnated or the periphery
of the outer strands would be free of plastic. The impregnation
would, however, exist between the outer strands and the core where
the plastic separating bands are provided. The impregnation of the
wire rope with plastic material need not be done right after
closure of the rope. In fact, after closure, the rope may be wound
on a reel and stored until the impregnation procedure is
undertaken. Thus, the two procedures may take place at different
times, as may be convenient to the manufacturer.
BRIEF DESCRIPTION OF THE DRAWINGS
[0018] The invention will now be described with reference to the
appended drawings in which:
[0019] FIG. 1 shows a schematic cross-sectional view of an eight
strand plastic impregnated wire rope with plastic bands between the
outer strands and the core in accordance with the present
invention;
[0020] FIG. 2 is a schematic longitudinal view of an arrangement
for carrying out the first stage of the method of the present
invention, producing a non-impregnated rope with plastic bands
between the outer strands and the core;
[0021] FIG. 3 is an end view of the device used in the arrangement
of FIG. 2 for guiding plastic bands towards the core; and
[0022] FIG. 4 is a schematic, longitudinal, generally
cross-sectional view of an extruder arrangement suitable for
carrying out the second stage of the method of the present
invention, namely the plastic impregnation of the rope.
DETAILED DESCRIPTION OF THE INVENTION
[0023] The present detailed description of the invention relates to
a preferred, non-limitative embodiment thereof as illustrated in
the drawings where the same features are designated by the same
reference numbers.
[0024] Referring to FIG. 1, it shows the wire rope 20 of the
present invention having eight outer strands 12 and an independent
wire rope core 14 with eight outer core strands 16. The wire rope
20 also has eight plastic bands 15 which prevent contact between
the outer strands 12 and the outer strands 16 of the core 14. This
contact is prevented not only when the rope is stationary, but also
and especially when it is operational. Preferably, the bands 15
have an accurate outer surface 17 which contacts the outer strands
12, matching the rounded portion of said strands 12.
[0025] There is enough space left between the plastic bands 15 to
allow molten plastic flow into and within the rope, and in the
present embodiment, the rope 20 is fully impregnated with the
plastic material 18.
[0026] FIG. 2 illustrates the first stage of the method of
manufacturing the rope of the present invention. In this FIG. 2, a
rotating performing head 22 is used to make a lubricated IWRC core
14 which is shown here in a longitudinal view rather than in
cross-section as in FIG. 1. This core is moved toward the closing
dies 24 as shown by arrow 23. Lubricated outer strands 12 are also
made in a conventional manner and moved toward the closing dies 24
while being rotated so as to be wound around the core 14 in the
closing operation. In accordance with the present invention,
plastic bands 15 are wrapped onto the core 14 so as to be
positioned under the outer strands 12 when the latter are wound
around the core 14 on which such bands 15 have been laid. The
laying of the bands 15 may be assisted by a hollow frusto-conical
device 26 mounted around the core 14 and connected to the
preforming head 22 by bolts 25 so as to rotate at the same speed as
said preforming head 22. Device 26 has eight internal guiding slots
28 as illustrated in FIG. 3. These slots 28 guide the bands 15 so
that they are laid on the core with the same lay as the outer
strands and, therefore, are positioned precisely under the outer
strands as they are wound on the core. This produces the first
stage wire rope 10 which has all the elements of the present
invention except that it is not impregnated with a plastic
material.
[0027] FIG. 4 illustrates the second stage of the method of the
present invention, namely the plastic impregnation. Here, the first
stage wire rope 10 passes through an extrusion cross head 31 of an
extruder where molten plastic is supplied through passages 32, 33,
34 as shown by the arrows. The plastic is supplied under pressure
and penetrates the rope 10 between dies 36 and 37 of the extruder.
The rearward flow of plastic pushes out excess lubricant 35 at the
rear of the die 36 and out of the cross head 31. A third die 38 is
connected by holes 39 to the atmosphere and serves to remove excess
molten plastic material 18 from the surface of the impregnated wire
rope 20. After leaving the extruder, the impregnated wire rope 20
is cooled to solidify the plastic material and then wound on a reel
or the like, constituting the final product of the present
invention.
[0028] It should be noted that other rope impregnating methods
could be used which are known in the art, particularly when partial
impregnation of the rope is desired.
[0029] Several samples of an 8 strand plastic impregnated wire rope
were prepared, with plastic bands provided between the outer
strands and the core in accordance with the present invention and
compared to the same kind of plastic impregnated wire rope, but
without such bands. The comparison was done by subjecting such
samples to a fatigue test using a ratio of the sheave diameter to
the diameter of the rope of D/d=25:1 and a load of 85,800 lbs
(39,000 kg). The average of standard plastic impregnated rope
samples (without bands) took 150,000 cycles to destruction, while
the average of plastic impregnated wire rope samples with plastic
bands between the outer strands and the core took 189,223 cycles to
destruction, leading to an improvement in the life of the rope of
26.1%. This is a significant improvement obtained due to the
present invention.
* * * * *