U.S. patent application number 09/870413 was filed with the patent office on 2002-01-10 for wire rope lubrication.
This patent application is currently assigned to UTILX Corporation. Invention is credited to Bertini, Glen J., Jessen, Glenn S..
Application Number | 20020002815 09/870413 |
Document ID | / |
Family ID | 27032802 |
Filed Date | 2002-01-10 |
United States Patent
Application |
20020002815 |
Kind Code |
A1 |
Bertini, Glen J. ; et
al. |
January 10, 2002 |
Wire rope lubrication
Abstract
A wire rope (10) includes a plurality of strands (12). The
strands are formed from individual wires or filaments (14). The
strands are wound about a central axis. A conduit (16) also extends
along said central axis. The conduit has walls that are foraminous
and permit radial flow of a lubricant. The lubricating compound is
injected into the channel (18) defined by the conduit. The
lubricating material migrates through the orifices in the conduit
wall and radially outwardly therefrom.
Inventors: |
Bertini, Glen J.; (Tacoma,
WA) ; Jessen, Glenn S.; (Everett, WA) |
Correspondence
Address: |
CHRISTENSEN, O'CONNOR, JOHNSON, KINDNESS, PLLC
1420 FIFTH AVENUE
SUITE 2800
SEATTLE
WA
98101-2347
US
|
Assignee: |
UTILX Corporation
|
Family ID: |
27032802 |
Appl. No.: |
09/870413 |
Filed: |
May 29, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
09870413 |
May 29, 2001 |
|
|
|
09546045 |
Apr 10, 2000 |
|
|
|
09546045 |
Apr 10, 2000 |
|
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09441407 |
Nov 16, 1999 |
|
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Current U.S.
Class: |
57/216 ; 57/213;
57/217 |
Current CPC
Class: |
D07B 1/12 20130101; D07B
1/144 20130101; D07B 2201/2063 20130101; D07B 2205/502
20130101 |
Class at
Publication: |
57/216 ; 57/213;
57/217 |
International
Class: |
D02G 003/36; D07B
001/06 |
Claims
The embodiments of the invention in which an exclusive property or
privilege is claimed are defined as follows:
1. A wire rope comprising: (a) a plurality of load-bearing strands
wrapped about a central axis and having a plurality of interstitial
spaces between the load bearing strands; and (b) a first conduit
disposed within the plurality of load bearing strands, the first
conduit adapted to permit a performance-enhancing compound to flow
therethrough and into contact with the plurality of load bearing
strands, wherein the first conduit includes a plurality of
perforations, each perforation being sized to permit a
predetermined portion of the performance-enhancing compound to pass
through each perforation and into contact with the plurality of
load bearing strands.
2. The wire rope of claim 1, wherein the performance-enhancing
compound is a lubricant.
3. The wire rope of claim 1, wherein the performance-enhancing
compound is a lubricant with a yield shear of greater than
zero.
4. The wire rope of claim 1, wherein the first conduit is
positioned along the central axis, the plurality of strands being
wound about the first conduit.
5. A wire rope comprising: (a) a plurality of load bearing strands
wrapped about a central axis and having a plurality of interstitial
spaces between the load bearing strands; and (b) a conduit disposed
within the plurality of load bearing strands, the conduit having a
length and adapted to permit a performance-enhancing compound to
flow therethrough, the conduit having a seam extending along the
length of the conduit, the seam permitting a predetermined portion
of the performance-enhancing compound to effuse outwardly through
the seam and into contact with the plurality of load bearing
strands.
6. The wire rope of claim 5, wherein the seam includes overlapping
portion and a layer of elastomeric material disposed around the
seam to permit an even outflow of performance-enhancing compound
from the tube.
7. The wire rope of claim 6, wherein the overlapping portions of
the tube form a helical seam extending the length of the tube to
permit a predetermined portion of the performance-enhancing
compound to pass through the helical seam.
8. The wire rope of claim 5, wherein the performance-enhancing
compound is a lubricant.
9. The wire rope of claim 5, wherein the performance-enhancing
compound is a lubricant with a yield shear of greater than
zero.
10. A method of lubricating a wire rope, comprising the steps of:
(a) injecting a performance-enhancing compound into the wire rope,
wherein the wire rope includes a plurality of strands wrapped
around an axis and a first conduit disposed within the plurality of
strands, wherein the first conduit is a strand of material wound to
form a tube, the tube having an exterior surface, an interior
surface and a plurality of seams extending between the exterior and
interior surfaces; and (b) allowing the performance-enhancing
compound to exude from the first conduit through the plurality of
seams to lubricate the plurality of strands.
11. The method of claim 10, wherein the performance-enhancing
compound is a lubricant with a yield shear of at least zero.
12. The method of claim 10, wherein the performance-enhancing
compound is a lubricant with a yield shear of greater than
zero.
13. A rope comprising: (a) a plurality of load-bearing strands
wrapped about a central axis and having a plurality of interstitial
spaces between the load bearing strands; and (b) a first conduit
disposed within the plurality of load bearing strands, the first
conduit adapted to permit a performance-enhancing compound to flow
therethrough and into contact with the plurality of load bearing
strands, wherein the first conduit includes a plurality of
perforations, each perforation being sized to permit a
predetermined portion of the performance-enhancing compound to pass
through each perforation and into contact with the plurality of
load bearing strands.
14. The rope of claim 13, wherein the performance-enhancing
compound is a lubricant.
15. The rope of claim 13, wherein the performance-enhancing
compound is a lubricant with a yield shear of greater than zero.
Description
[0001] This application is a Continuation-In-Part of U.S. patent
application Ser. No. 09/546,045, filed Apr. 10, 2000, now
abandoned, which is a Continuation-In-Part of U.S. patent
application Ser. No. 09/441,407, filed Nov. 16, 1999, the
disclosure of which is hereby expressly incorporated by
reference.
FIELD OF THE INVENTION
[0002] This invention relates to wire ropes, and more particularly,
to a method and an apparatus for lubricating wire ropes.
BACKGROUND OF THE INVENTION
[0003] Wire ropes traditionally comprise a plurality of wires or
filaments that are wound or twisted into multi-wire strands, which
in turn are twisted about each other to form a wire rope. Wire
ropes are used in a variety of applications including drag lines,
elevators, bridges, hoists, and marine tow ropes. Wire ropes are
stressed and relaxed numerous times during their life cycle. They
also undergo frictional stress to a certain degree in straight
pulls but more so when they traverse a sheave or are wound onto a
drum. The wires and strands are thus caused to move in relation to
each other causing wear in the rope. Wire ropes are lubricated to
promote unrestricted movement of the rope, minimal fatigue and
frictional wear. Lubrication also provides protection against rust
and corrosion.
[0004] Wire ropes are typically lubricated from the outside with a
lubricating material such as an oil or a grease. It is common to
lubricate a wire rope by dripping oil on it or pulling it through
an oil bath. Thick coats of grease have also been applied to wire
ropes from the outside with the hope that the grease will penetrate
into the interior of the rope. These methods of lubrication are not
long-term solutions because the lubricants evaporate or are wiped
away during normal use.
[0005] In recent years, wire rope manufacturers have tried other
methods to lubricate wire ropes. For example, a solid core made of
a porous polymer, or other absorbent material, has been positioned
in a wire rope. The solid core is made of a polymer and a
lubricant. When the core is stressed, lubricating material is
squeezed from the solid core. These lubrication techniques are time
limited because of the finite lubricant supply in the cores.
Attempts have been made to replenish the lubricant in rope cores by
pouring additional lubricant over the rope or pulling it through a
bath. These methods have not proven to extend the life of a wire
rope for any appreciable amount of time.
SUMMARY OF THE INVENTION
[0006] The present invention solves the shortcomings of the prior
art methods for lubricating wire ropes by providing a wire rope
having one or more channels or conduits running in the direction of
the axis of the wire rope. The conduits are capable of receiving
and carrying a lubricant or other performance-enhancing material. A
lubricant, for example, is injected axially along the channel. The
lubricant diffuses out of the conduit and into the regions between
the filaments and the strands comprising the wire rope to lubricate
the wire rope during its use cycle. In a preferred embodiment, a
lubricated wire rope includes a plurality of load-bearing strands
wrapped about a central elongated axis. A first conduit is
physically disposed within the plurality of load-bearing strands.
The first conduit is adapted to permit a lubricating compound to
flow therethrough. The conduit is permeable to the lubricating
compound to permit a predetermined portion of the compound to
diffuse through the first conduit into contact with the strands and
the filaments making up the strands, thereby lubricating them.
BRIEF DESCRIPTION OF THE DRAWINGS
[0007] The foregoing aspects and many of the attendant advantages
of this invention will become more readily appreciated as the same
become better understood by reference to the following detailed
description, when taken in conjunction with the accompanying
drawings, wherein:
[0008] FIG. 1 is a perspective view of a wire rope constructed in
accordance with one embodiment of the present invention;
[0009] FIG. 2A is cross-section of the wire rope of FIG. 1;
[0010] FIGS. 2B-2E are alternate embodiments of that shown and
described in conjunction with FIG. 2A;
[0011] FIG. 3A is a cross-section of an alternate embodiment of the
wire rope of FIGS. 1 and 2;
[0012] FIGS. 3B-3D are alternate embodiments of that shown in and
described in conjunction with FIG. 3A;
[0013] FIG. 4 is an alternate embodiment of the wire rope of FIG. 1
showing a perforated conduit axially disposed within the wire
rope;
[0014] FIG. 5 is an alternate embodiment of the wire rope of FIG. 4
showing a tube having a longitudinally extending slot axially
disposed within the wire rope;
[0015] FIG. 6 is an alternate embodiment of a wire rope of FIG. 5
showing a multi-ply tube axially disposed within the wire rope;
and
[0016] FIG. 7 is an alternate embodiment of a wire rope of FIG. 3B
showing a catalyst disposed within the interstices of the wire
rope.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0017] Referring to FIG. 1, a wire rope 10 includes a plurality of
load-bearing strands 12 that are wound about each other and a
central axis to form a load-bearing wire rope 10. In a typical
configuration, each of the strands is composed of a plurality of
wires or filaments 14. These wires or filaments are first wound
about each other to form a strand before the wire rope 10 is
manufactured from a plurality of strands. As used herein the term
strand refers both to a structure comprising a single wire or
filament or multiple wires or filaments.
[0018] In accordance with the preferred embodiment of the present
invention, a flexible conduit 16 is positioned along the axis of
the wire rope 10. The conduit 16 has a central channel 18 for
receiving a lubricating compound. In this embodiment, the conduit
16 runs along the axis of the wire rope 10 and the strands 12 are
wound about the conduit 16.
[0019] The conduit 16 can be made of polyethylene, nylon, aromatic
polyamides (e.g., Kevlar.RTM.), polytetrafluoroethylene, or other
suitable polymeric materials. The conduit 16 is manufactured so
that it is flexible and chemically permeable to the
performance-enhancing compound. Chemically permeable materials
permit the passage of liquids, gas, molecules, or ions through
intermolecular spaces. The use of such materials allows one to
control the rate of permeation by the choice of materials (tube and
fluid), thereby assuring a consistent penetration along the length
of the conduit 16, especially for an extremely low mass flux.
[0020] Thus the performance-enhancing compound can diffuse radially
outwardly through the conduit walls so that the lubricating
material can come into contact with the strands 12. The conduit can
also be made of other perforated or foraminous materials, for
example, sintered metals. A foraminous conduit is one with a
plurality of small openings or orifices.
[0021] The degree of permeability of the conduit 16 can be altered
by one of ordinary skill in the manufacture of polymeric material
to provide a rate of permeability that will satisfy the lubrication
requirements of wire ropes in different applications. The rate of
diffusion of the performance-enhancing compound through the conduit
walls can easily be regulated by one of ordinary skill by
selectively choosing or altering the molecular size or structure of
the lubricating compound (thus altering the diffusivity or
solubility), the thickness of the conduit, the pressure at which
the fluid is delivered, and finally the operating temperature of
the wire rope.
[0022] The conduit 16 must have sufficient physical strength to be
incorporated in the wire rope 10 and adequate thermal properties
for use in maximum and minimum thermal environments in which the
wire rope 10 may be used. Preferably, the conduit 16 has the
thinnest wall possible to allow lubricating compound storage and
free flow. The conduit 16 must also be capable of withstanding the
normal operating temperatures of the wire rope. As a non-limiting
example, the wall thickness of the conduit 16 is suitably between
{fraction (1/64)} and {fraction (1/32)} of an inch. Although a
cylindrical or nearly cylindrical geometry is the preferred
geometry for the conduit 16, it should be apparent that other
hollow geometries are also included within the scope of the present
invention.
[0023] A wide variety of performance-enhancing materials can be
injected through the conduit 16. These include but are not limited
to lubricants, corrosion inhibitors, antioxidants, UV stabilizers,
water repellents, water-proofers, water scavengers, ion scavengers,
and other performance improving materials and compounds. One of
ordinary skill, once understanding the utility of the invention,
will readily be able to inject a wide variety of other
performance-enhancing materials or compounds in accordance with the
present invention.
[0024] The lubricating compounds especially useful in accordance
with the present invention include a wide variety of existing
lubricants that can flow through the channel 18 and diffuse through
the walls of the conduit 16. Typical petroleum-based lubricants can
be used with porous or foraminous conduits. Monomeric, oligmeric
and low molecular weight polymeric silanes and siloxanes can also
be used and have the capability of diffusing through the walls of
selected solid polymeric tubes.
[0025] Where the conduit 16 is not foraminous or sintered, the
lubricating materials must be of sufficiently low molecular weight
to permeate through the polymeric conduit wall. Low molecular
weight lubricants suffer from a short-lived presence on the
surfaces to be lubricated due to their volatility and rapid surface
transport resulting from their low viscosity. The present invention
involves the use of an organosilicone fluid, which comprises
silanes of the general formula
(RO).sub.xSiR'.sub.yR".sub.zR'".sub.(4-x-y-z)
[0026] where R denotes an aliphatic, aromatic, or an arene radical
with 1 to 12 carbon atoms, preferably 1 to 2 carbon atoms; R'
denotes an aliphatic, aromatic, or an arene radical with 0 to 12
carbon atoms; R" denotes an aliphatic, aromatic, or an arene
radical with 0 to 12 carbon atoms; and R'" denotes an aliphatic,
aromatic, or an arene radical with 0 to 12 carbon atoms and
mixtures and partial hydrolysates thereof. It should be understood
that, within the scope of this invention, when carbon atoms=0, R',
R", and R'" are atoms, which may have a valance of -1, such as
hydrogen, florine, chlorine, and bromine.
[0027] Still referring to the formula above, the subscript "x" is
between 1 to 4, but preferably 2. The subscripts "y" and "z" are
from 0 to 4, but the sum of x, y, z, and 4-x-y-z must be 4. The
aliphatic, aromatic, or arene radicals may be substituted with
halogens, hydroxy or other radicals without departing from the
spirit of this invention. Such substitutions can be used to control
the permeation rate, and add functionality such as UV stabilization
or antioxidation or other desirable properties to extend the life
of the wire rope. Examples of materials which are encompassed
within this general formula are dimethyldimethoxysilane,
dimethyldiethoxysilane, phenylmethyldimethoxysil- ane,
naphthylmethyldiethoxysilane, methyltrimethoxysilane, and
bromophenylethyldiethoxysilane.
[0028] The alkoxy functionality and especially dialkoxy
functionality (x=2) designated in the general formula above as
(RO).sub.x
[0029] solves the problem of the lubricant having too high a
volatility and too low a viscosity. This alkoxy functionality
provides for the hydrolysis and condensation reaction with water,
which is ubiquitous in either the liquid or vapor state in the
environments where the wire ropes are used, such that longer chain
oligomers or polymers are formed shortly after the supplied
lubricant diffuses out of the conduit 16. A mixture of compounds
primarily made up on a molar basis with x=2 and a smaller molar
amount with x=1 can be utilized to end-block the growing oligomer
chain to prevent excess viscosity of the fully hydrolyzed material.
For example, if the molar ratio of x=2
[0030] to x=1 were 50 to 1, the resulting siloxane mixture would
have an average degree of polymerization of 25.
[0031] Alternatively, large viscosity increases could be encouraged
where the application requires a higher viscosity, such as where
the operating temperature is very high, by including a small molar
ratio in the mixture of materials in which x=3 or x=4. Where alkoxy
functionality exceeds 2, cross-linking of oligomer chains can yield
gel-like or grease-like consistencies. For example, a mixture of
75-99% by weight of dimethyldimethoxysilane together with 1-25% by
weight of methyltrimethoxysilane would result in lubricants with
cross-linked chain structure and rheologies similar to greases used
today in the wire rope industry. Thus, mixtures can be made of
materials where the primary component has x=2, and smaller amounts
of x=1 and/or x=3 or 4 can be blended to yield any desired
rheology.
[0032] Another way to control the speed and degree of
polymerization is to include any of several hydrolysis and/or
condensation catalysts known in the art on the surface of the
conduit 16, on the surface of the wire rope stands, or in the
mixture of lubricant greases 73 which are included in the
itersticial spaces of the strands during the manufacture of the
rope, as seen in FIG. 9. A catalyst may be chosen from a group that
includes titanates, such as tetraisopropyltitanate.
[0033] Other low viscosity, low molecular weight organic lubricants
and other synthetic lubricants known in the art can also be
used.
[0034] It is contemplated that during manufacture and use, it is
possible that the conduit 16 can be pinched or crushed. One way to
maintain an open channel 18 in a conduit 16 is to introduce a fluid
into the tube under pressure during the manufacturing process. This
would balance the inward pressure on the central conduit during
normal strand compression procedures and prevent the conduit from
deforming or collapsing. This technique would also prevent collapse
of the tube during compacting or swaging operations.
[0035] Referring now to FIG. 2B, the first alternate embodiment of
a wire rope 30 incorporates the concepts of the present invention.
The wire rope 30 comprises six strands 32 wound about a central
core strand 34. Strand 34 is comprised of a plurality of individual
wires or filaments that are wound about a central tube or conduit
36. The conduit 36 has a central channel into which
performance-enhancing materials or compounds can be injected. The
performance-enhancing materials can migrate through the conduit 36
radially outwardly into first the central strand 34 and then the
exterior strands 32.
[0036] Referring to FIG. 2C, a wire rope 40 comprises six exterior
strands 42 wound about a central strand 46. Central strand 46 is in
turn comprised of several smaller strands that are encapsulated in
a polyethylene jacket. The type of strand and jacket making up the
central strand is described in further detail in conjunction with
FIGS. 3A-3D. In this embodiment, the six outer strands 42 carry
central conduits 48 into which performance-enhancing fluids or
materials can be injected. These performance-enhancing materials
again migrate outwardly through the wires or filaments comprising
the individual strands 42.
[0037] Referring to FIG. 2D, wire rope 50 comprises six outer
strands 52 wound about a central core strand 54. Alternate ones of
the outer strands 52 are composed of wires wound about a central
conduit 56. Central strand 54 similarly carries a central conduit
58. Performance-enhancing materials can be injected into the
conduits 56 and 58 in a manner similar to that previously
described.
[0038] Finally, referring to FIG. 2E, yet another embodiment of a
wire rope 60 comprises six outer strands 62 wound about a central
core strand 64. In this embodiment, conduits 64 are not positioned
within the individual strands but in the triangularly shaped
cavities formed between two adjacent outer strands and the inner
strand 64. Six of these cavities carry six conduits 64. Again,
performance-enhancing materials can be injected into these conduits
64 in a manner similar to that described above.
[0039] Referring now to FIG. 3A, a cushioned core rope 20 is
illustrated. A typical cushioned core rope is manufactured in the
same manner as an ordinary wire rope. In this embodiment, the rope
comprises strands 22 wound about a central strand 24. A
polyethylene jacket 26 is extruded around the entire wire rope. The
purpose of the polyethylene jacket is to provide a degree of
cushioning and lubrication to the individual strands 22. While the
polyethylene jacket is formed about the cushioned core rope 20,
care is taken so that the polymeric material does not flow into the
interstitial spaces or interstices 28 between the individual
filaments of the strands 22. These interstices form a multiplicity
of channels that spiral in an axial direction along the entire
length of the cushioned core rope 20. In accordance with the
present invention, it is possible to inject a performance-enhancing
material axially through these interstices 28 and provide
additional lubrication to a cushioned core rope.
[0040] Referring now to FIG. 3B, a wire rope 70 of the cushioned
core type described in conjunction with FIG. 3A has a central
conduit 72 positioned in the central strand 74 of the rope 70.
Individual wires of the central strand 74 are wound about the
conduit 72. A performance-enhancing material can be injected into
the conduit 72 as described above.
[0041] Referring to FIG. 3C, a cushioned core wire rope 80 is
similar to that shown in FIG. 3B. This embodiment, however, differs
from that of FIG. 3B in that the interstitial spaces between the
outer strands 92 and the inner strand 94 are filled with the
cushioning material. Additionally, the central conduit 72 is
replaced by a wire or filament 82. Conduits 84 are positioned in
alternating triangularly shaped regions created between two
adjacent exterior strands 86 and central strand 82. In this
embodiment, three conduits 84 are employed and positioned in
alternating ones of the triangularly shaped regions.
Performance-enhancing materials can be injected into these conduits
similar to that described above.
[0042] Finally, referring to FIG. 3D, cushioned core rope 90 is
similar to that described in conjunction with FIG. 3B above. This
embodiment, however, differs from that of FIG. 3B in that the
interstitial spaces between the outer strands 92 and the inner
strand 94 are filled with the cushioning material. A conduit 96 is
positioned in the center of the central strand 94 replacing the
central wire during manufacture. A performance-enhancing material
can be injected into conduit 96 in the manner similar to that
described above.
[0043] One of ordinary skill will be able to devise a number of
efficient ways to inject material into the channel 18 of the wire
rope of FIGS. 1 or 2 or through the interstices 28 of the cushioned
core wire rope 20 of FIGS. 3A and 3B. A variety of connecting
devices for injecting a fluid into electrical cable are disclosed
in co-pending provisional patent application Ser. No. 60/155,279,
filed Oct. 11, 1999, attorney docket No. UTLX-1-14551. These
connecting devices can easily be adapted for use in conjunction
with wire ropes.
[0044] Referring now to FIG. 4, an alternate embodiment of a wire
rope 110 formed in accordance with the present invention is
illustrated. The wire rope 110 is identical in materials and
operation as the preferred embodiment described above, with the
following exception. Instead of a conduit 16, this alternate
embodiment includes a perforated conduit 116. The perforated
conduit 116 can be made of any suitable material, but a metal or
plastic material is preferred. The conduit has a plurality of
circular or irregular holes 130 pierced either mechanically or
thermally in a regular or irregular pattern. The circular or
irregular holes 130 have a minimum diameter, d.sub.min, which
allows lubricating material with a spherical particle that has a
slightly smaller diameter than d.sub.min to pass through to the
wire rope strands 112.
[0045] Many wire rope lubricants include solid particles such as
but not limited to graphite, molybdenum disulfide, Teflon, and
titanium nitride in their formulation. Where the use of these solid
lubricants are desired in combination with a foraminous conduit,
the majority of the solid particles must have an average diameter
smaller then d.sub.min. Because d.sub.min will change
proportionally with an increase in the wire rope tension, this
change of d.sub.min should be accounted for when choosing a
lubricant. In addition to lubricant distribution based upon
particles passing through d.sub.min, the rheology of the lubricant
can be varied to accommodate the geometry of the conduit. The
rheology should be chosen to optimize the performance and economy
of the lubricating system.
[0046] Lubricants with a yield shear greater than zero, such as
Bingham plastics and thixotropic fluids, are useful when combined
with a foraminous conduit. A lubricant with a radial flow
resistance greater than the axial flow resistance will provide a
more uniform lubrication along the length of the wire rope.
Ideally, the radial flow rate would equal zero until a critical
pressure was reached along the entire length of the wire rope that
exceeded the yield shear of the lubricant system even if the
conduit had a considerable static head differential along its
length (for example, a vertical mineshaft application). Although a
compound having a yield shear greater than zero is preferred, other
compounds, such as a compound with a yield shear equal to zero, are
also within the scope of the present invention. A non-limiting
example of a compound having a yield shear equal to zero is motor
oil.
[0047] Referring now to FIG. 5, another alternate embodiment of a
wire rope 310 formed in accordance with the present invention will
now be described in greater detail. The wire rope 310 is identical
in materials and operation as the alternate embodiment wire rope
described above, with the following exception. The wire rope 310
includes a tube 316 having a longitudinally extending seam 330.
[0048] The tube 316 is formed from a metal, plastic, elastomeric,
or laminate strip that is wound in an overlapping helix. Lubricant
passes through the seam 330 between overlapping sections and
travels a distance equal to the width of the strip multiplied by
the percentage of overlap. As a non-limiting example, if the tube
316 were made from a one inch strip and the overlap is 40%,
lubricant exudes between the helixes for a distance of 0.4 inches
before exiting the tube. The overlap may vary from 0% to 99%, but
the preferred embodiment would be from 20% to 70%. A 50%
overlapping helix, for example, can be stretched almost 100% before
there would be any gaps between adjacent helixes.
[0049] The tube 316 can be varied to accommodate many various
lubrication particle sizes and the desired lubrication rheology.
The following properties of the tube 316 can be adjusted: strip
width; overlap of the helix; tightness and tolerances of the
overlap; nature of the interface between the overlapping helixes;
mechanical properties of the materials; and interaction of the
conduit with the geometry of the surrounding wire rope. The
tightness and the surface tolerances of the overlap affect the
exudation rate because the microscopic flow paths between two
plates effectively vary the minimum distance therebetween. For
example, a rough surface would allow more flow than a smooth
surface. Also, the seam 330 could be multiple seams, a straight
seam, or a combination of straight and overlapping helix seams.
[0050] Now referring to FIG. 6, another alternate embodiment of a
wire rope 510 formed in accordance with the present invention will
now be described in greater detail. The wire rope 510 is identical
in materials and operation as the alternate embodiment wire rope
310 described above, with the following exception. The wire rope
510 includes a centrally located tube 516 having a longitudinally
extending seam that includes a layer 518 and a metallic base 520.
The layer 518 may be an elastomeric material and is suitably
attached to one side of the base 520. Although the base 520 is
coated on one side with the layer 518, other embodiments, such as
having a layer 518 on both sides of the base 520, are also within
the scope of the present invention.
[0051] As noted above, the nature of the interface between
overlapping helixes can also be used to control exudation
properties. As a non-limiting example, a tube having an overlapping
seam made from a metal/elastomeric laminate would restrict fluid
flow greater than a tube that had a metal to metal interface
between the overlaps. Both the mechanical properties of the
material and the interaction of the tube with the wire rope strands
affect the radial flow of the lubricant as the internal pressure of
the lubricant in the conduit increases. Materials having a greater
elasticity will be more apt to deform as the internal pressure
increases. As the conduit begins to deform, the layout of the wire
rope strands can affect the radial flow of the lubricant.
[0052] For a non-limiting example, if the lay of the overlapping
seam were right handed and the strip width and the overlap were
chosen to match the lay angle of the overlaying wire strands and
the strands were also right handed, an increase in internal
pressure would deform the conduit and allow a greater lubricant
flow. By changing the lay of the conduit from right handed to left
handed, the overlaying stands would restrict the deformation of the
overlapping conduit, and thus reduce the radial flow through a tube
with the same mechanical properties.
[0053] While the preferred embodiments of the invention have been
illustrated and described, it will be appreciated that various
changes can be made thereto without departing from the spirit and
scope of the invention. As a non-limiting example, such ropes may
be formed from strands of synthetic polymeric materials, such as
nylon or Kevlar.RTM.. In still yet other embodiments, the ropes may
be made from strands of natural material, such as cotton or hemp.
As a result, although the foregoing descriptions have been
described as being applicable to wire ropes, it should be apparent
that other types of ropes made from strands of synthetic or natural
materials are also within the scope of the present invention.
[0054] While the preferred embodiment of the invention has been
illustrated and described, it will be appreciated that various
changes can be made therein without departing from the spirit and
scope of the invention.
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