U.S. patent application number 13/831142 was filed with the patent office on 2014-09-18 for twelve-strand rope employing jacketed sub-ropes.
This patent application is currently assigned to SAMSON ROPE TECHNOLOGIES. The applicant listed for this patent is Samson Rope Technologies. Invention is credited to Justin Gilmore, David O'Neal, Dennis Patrick Sherman.
Application Number | 20140260927 13/831142 |
Document ID | / |
Family ID | 51521455 |
Filed Date | 2014-09-18 |
United States Patent
Application |
20140260927 |
Kind Code |
A1 |
Gilmore; Justin ; et
al. |
September 18, 2014 |
TWELVE-STRAND ROPE EMPLOYING JACKETED SUB-ROPES
Abstract
A rope structure is formed by forming a sub-rope structure
comprising a core and a jacket, twisting the sub-rope structure to
form a twisted sub-rope structure, and forming the rope structure
by braiding together a plurality of lengths of the twisted sub-rope
structure.
Inventors: |
Gilmore; Justin; (Lafayette,
LA) ; Sherman; Dennis Patrick; (Statham, GA) ;
O'Neal; David; (Lafayette, LA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Samson Rope Technologies; |
|
|
US |
|
|
Assignee: |
SAMSON ROPE TECHNOLOGIES
Ferndale
WA
|
Family ID: |
51521455 |
Appl. No.: |
13/831142 |
Filed: |
March 14, 2013 |
Current U.S.
Class: |
87/8 |
Current CPC
Class: |
D07B 2201/209 20130101;
D07B 2501/2061 20130101; D04C 1/12 20130101; D07B 1/02 20130101;
D07B 2201/2095 20130101; D07B 2201/1096 20130101 |
Class at
Publication: |
87/8 |
International
Class: |
D07B 5/00 20060101
D07B005/00 |
Claims
1. A method of forming a rope structure comprising the steps of:
forming a sub-rope structure comprising a core and a jacket;
twisting the sub-rope structure to form a twisted sub-rope
structure; forming the rope structure by braiding together a
plurality of lengths of the twisted sub-rope structure.
2. A method as recited in claim 1, further comprising the steps of:
forming strands from filaments; and combining lengths of the
strands to form the core and the jacket of the sub-rope
structure.
3. A method as recited in claim 2, in which: the step of combining
the strands to form the core comprises the step of braiding
together twelve lengths of the strands; and the step of combining
the strands to form the jacket comprises the step of braiding
together twelve lengths of the strands around the core.
4. A method as recited in claim 1, in which the step of twisting
the sub-rope structure to form the twisted sub-rope structure
further comprises the steps of: determining an amount of braid
twist applied when the lengths of twisted sub-rope structures are
braided together to form the rope structure; and applying
sufficient pre-twist when forming the twisted sub-rope structure to
compensate for the braid twist.
5. A method as recited in claim 1, further comprising the step of
arranging a filter member between the core and the jacket.
6. A method as recited in claim 1, in which the step of forming the
rope structure comprises the step of braiding together twelve of
lengths of the twisted sub-rope structure.
7. A rope structure comprising a plurality of lengths of a sub-rope
structure comprising a core and a jacket, where a reference line
substantially parallel to a longitudinal axis of the sub-rope
structure when the rope sub-structure is initially formed is
substantially parallel to the longitudinal axis of the rope
sub-structure when the plurality of lengths of the sub-rope
structure are braided together to form the rope structure.
8. A rope structure as recited in claim 7, in which: lengths of
strands are braided together to form the core and the jacket of the
sub-rope structure; and the strands comprise filaments.
9. A rope structure as recited in claim 8, in which: the core of
the rope sub-structure comprises twelve lengths of the strands; and
the jacket of the rope sub-structure comprises twelve lengths of
the strands.
10. A rope structure as recited in claim 8, further comprising a
filter member between the core and the jacket.
11. A rope structure as recited in claim 8, in which the rope
structure comprises twelve of lengths of the sub-rope
structure.
12. A method of forming a rope structure comprising the steps of:
providing a rope sub-structure comprising a core and a jacket;
determining an amount of braid twist obtained when braiding the
rope sub-structure to form the rope structure; and forming a
twisted sub-rope structure by pre-twisting the sub-rope structure
to compensate for the braid twist; braiding lengths of the twisted
sub-rope structure together to form the rope structure.
13. A method as recited in claim 12, further comprising the steps
of: forming strands from filaments; and combining lengths of the
strands to form the core and the jacket of the sub-rope
structure.
14. A method as recited in claim 13, in which: the step of
combining the strands to form the core comprises the step of
braiding together twelve lengths of the strands; and the step of
combining the strands to form the jacket comprises the step of
braiding together twelve lengths of the strands around the
core.
15. A method as recited in claim 13, further comprising the step of
arranging a filter member between the core and the jacket.
16. A method as recited in claim 13, in which the step of forming
the rope structure comprises the step of braiding together twelve
of lengths of the twisted sub-rope structure.
Description
TECHNICAL FIELD
[0001] The present invention relates to rope structures, systems,
and methods and, in particular, to such structures, systems, and
methods in which a twelve-strand rope is formed by jacketed
sub-ropes.
BACKGROUND
[0002] Rope structures are commonly used when a tension load is to
be applied between two structures. One common use of a rope
structure is as a mooring tether or line adapted to extend between
a first structure (e.g., oil drilling or production platform or
vessel) and a second structure (an anchor on the sea floor).
[0003] Mooring tethers or lines are commonly formed with a core for
tensile strength and a jacket to cover and protect the core. The
core in turn is formed by strands. The protective jacket prevents
visual inspection of the load bearing core and/or the strands
forming the load bearing, so it is difficult to determine whether
the load bearing core of a jacketed mooring tether or line may be
subject to failure.
[0004] The need thus exists for improved mooring lines that
facilitate visual inspection of individual strands of a jacketed
core.
SUMMARY
[0005] The present invention may be embodied as a method of forming
a rope structure comprising the following steps. A sub-rope
structure comprising a core and a jacket is formed. The sub-rope
structure is twisted to form a twisted sub-rope structure. The rope
structure is formed by braiding together a plurality of lengths of
the twisted sub-rope structure.
[0006] The present invention may also be embodied as a rope
structure comprising a plurality of lengths of a sub-rope structure
comprising a core and a jacket. A reference line substantially
parallel to a longitudinal axis of the sub-rope structure when the
rope sub-structure is initially formed is substantially parallel to
the longitudinal axis of the rope sub-structure when the plurality
of lengths of the sub-rope structure are braided together to form
the rope structure.
[0007] The present invention may be embodied as a method of forming
a rope structure comprising the steps following steps. A rope
sub-structure comprising a core and a jacket is provided. An amount
of braid twist obtained when braiding the rope sub-structure to
form the rope structure is determined. A twisted sub-rope structure
is formed by pre-twisting the sub-rope structure to compensate for
the braid twist. Lengths of the twisted sub-rope structure are
braided together to form the rope structure.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a schematic block diagram illustrating a first
example step of a process of making a twelve-strand rope structure
of the present invention;
[0009] FIG. 2 is a schematic block diagram illustrating a second
example step of a process of making a twelve-strand rope structure
of the present invention;
[0010] FIG. 3 is a schematic block diagram illustrating a third
example step of a process of making a twelve-strand rope structure
of the present invention;
[0011] FIG. 4 is a somewhat schematic section view of an example
sub-rope produced by the third example step depicted in FIG. 3;
[0012] FIG. 5 is a schematic block diagram illustrating a fourth
example step of a process of making a twelve-strand rope structure
of the present invention;
[0013] FIG. 6 is a somewhat schematic plan view of an example
sub-rope produced by the third example step depicted in FIG. 3;
[0014] FIG. 7 is a somewhat schematic plan view of an example
twisted sub-rope produced by the fourth example step depicted in
FIG. 5;
[0015] FIG. 8 is a schematic block diagram illustrating a fifth
example step of a process of making a twelve-strand rope structure
of the present invention;
[0016] FIG. 9 is a somewhat schematic depiction of an example
twelve-strand rope of the present invention; and
[0017] FIG. 10 is a somewhat schematic section view of an example
sub-rope produced by the third example step depicted in FIG. 3 but
further comprising a filter member.
DETAILED DESCRIPTION
[0018] Referring to FIGS. 1-5 of the drawing, depicted therein are
first, second, third, fourth, and fifth steps, respectively, of a
method of fabricating a twelve-strand rope structure in accordance
with, and embodying, the principles of the present invention. FIG.
6 schematically illustrates an example twelve-strand rope 20
manufactured using the systems and methods depicted in FIGS.
1-5.
[0019] Referring initially to FIG. 1 of the drawing, schematically
depicted therein is a first or yarn forming step performed by a
twisting system 30 comprising a creel system 32 and a first twister
34. The creel system 32 supports spools or bobbins 40 on which are
stored filaments 42. The first twister 34 unspools the filaments 42
from the bobbins 40 and twists the filaments 42 together to obtain
yarns 44 comprising a plurality of the filaments 42. The yarns 44
are taken up on yarn bobbins 46 for storage and subsequent
processing as will be describe in further detail below. The creel
system 32 and first twister 34 are or may be conventional and will
not be described herein in further detail. The filaments 42
typically comprise one or more synthetic fibers, and the
manufacture of the yarns 44 from the filaments 42 using the creel
system 32 and first twister 34 also may be conventional.
[0020] Schematically depicted in FIG. 2 of the drawing is a second
or sub-rope core forming step performed by a first braiding system
50 comprising a 12-strand braider system 52 and a plurality of the
yarn bobbins 46 each containing a length of the yarn 44. The
12-strand braider system 52 is or may be conventional and will not
be described herein in further detail. For simplicity, five yarn
bobbins 46 are depicted in the schematic representation of the
first braiding system 50 in FIG. 2, but it will be understood that
twelve yarn bobbins 46 and twelve lengths of the yarn 44 are used
by the 12-strand braider system 52 of the first braiding system 50.
In particular, the 12-strand braider system 52 pulls the twelve
lengths of yarn 44 and combines these lengths of yarn 44 to form a
core structure 54 in the form of a twelve-strand braided rope. The
core structure 54 is taken up on a core bobbin 56.
[0021] FIG. 3 of the drawing schematically depicts a third or
sub-rope forming step performed by a second braiding system 60
comprising a cover braider system 62, a plurality of the yarn
bobbins 46 each containing a length of the yarn 44, and one the
core bobbins 56 containing a length of the core structure 54. The
example cover braider system 62 is or may be conventional and will
not be described herein in further detail. For simplicity, five
yarn bobbins 46 are depicted in the schematic representation of the
second braiding system 60 in FIG. 3, but it will be understood that
twelve yarn bobbins 46 and twelve lengths of the yarns 44 are used
by the cover braider system 62 of the second braiding system 60. In
particular, the cover braider system 62 pulls the core structure 54
and the twelve yarns 44 and combines the core structure 54 and the
pulled yarns 44 to form a sub-rope structure 64.
[0022] As perhaps best shown in FIG. 4 of the drawing, the example
sub-rope structure 64 comprises a jacket structure 68 formed by the
yarns 44 and a core formed by the core structure 54. The sub-rope
structure 64 thus takes the form of a jacketed twelve-strand
braided rope. The sub-rope structure 64 is taken up on a sub-rope
bobbin 66.
[0023] FIG. 5 of the drawing schematically depicts a fourth or
pre-twist forming step performed by a second twister system 70
comprising a second twister 72 and a sub-rope bobbin 68 comprising
a length of the sub-rope structure 64. The second twister 72
unspools the length of sub-rope structure 64 from the sub-rope
bobbin 68 and twists the sub-rope structure 64 to obtain a twisted
sub-rope structure 74. The twisted sub-rope structure 74 is taken
up on a twisted sub-rope bobbin 76 for storage and subsequent
processing as will be describe in further detail below. The second
twister 72 is or may be conventional and will not be described
herein in further detail.
[0024] FIGS. 6 and 7 schematically represent the untwisted sub-rope
structure 64 and the twisted sub-rope structure 74 obtained after
the untwisted sub-rope structure 64 is processed by the second
twister system 70. In particular, for reference purposes, a
straight reference line 78, shown as a dashed line in FIG. 6, is
defined along a length of the untwisted sub-rope structure 64 and
parallel to the longitudinal axis of that structure 64. It should
be apparent that the reference line 78 is not a feature of the
sub-rope structure 64 but would be formed solely for the purpose of
illustrating the difference between the untwisted sub-rope
structure 64 and the twisted rope structure 74. After the pre-twist
step is performed, the reference line 78 follows a helical path, as
shown by dashed lines in FIG. 7, centered about the longitudinal
axis of the twisted rope sub-structure 74. A similar convention of
straight and angled (helical) dashed lines is used in FIG. 5 to
distinguish between the un-twisted sub-rope structure 64 going into
the second twister system 70 and the twisted sub-rope structure 74
leaving the second twister system 70.
[0025] FIG. 8 of the drawing schematically depicts a fifth or rope
forming step performed by a third braiding system 80 comprising a
12-strand braider system 82 and a plurality of the twisted sub-rope
bobbins 76 each containing a length of the twisted sub-rope
structure 74. The example 12-strand braider system 92 is or may be
conventional and will not be described herein in further detail.
For simplicity, five sub-rope bobbins 76 are depicted in the
schematic representation of the third braiding system 80 in FIG. 8,
but it will be understood that twelve sub-rope bobbins 76 and
twelve lengths of the twisted sub-rope structure 74 are used by the
12-strand braider system 82 of the third braiding system 80. In
particular, the 12-strand braider system 82 pulls the twelve
lengths of the twisted sub-rope structure 74 and combines these
lengths of twisted sub-rope structure 74 to form the rope structure
20 comprising a plurality of assembled sub-rope structures 84. The
rope structure 20 is taken up on a 12-strand rope bobbin 86 for
subsequent storage and handling prior to use.
[0026] 12-strand braiders such as the example 12-braider system 82
inherently form a twist in the sub-rope structures braided thereby.
For many sub-rope structures, the twist is inconsequential. For
jacketed sub-rope structures, the twist formed by the 12-strand
braider deforms the jacketed sub-rope structure and thus the
twelve-strand braided rope formed thereby. Accordingly, jacketed
sub-rope structures are not effectively used to form a rope
structure using 12-strand braiders.
[0027] The Applicants have discovered that the performance of the
pre-twist step to twist sub-rope structure ultimately taken up by a
conventional 12-strand braider can compensate for the twist applied
by a 12-strand braider. In particular, the pre-twist step performed
by the second twister system 70 is configured to yield a twisted
sub-rope structure 74 having an amount of pre-twist in a first
direction to compensate for an amount of braid twist applied in a
direction opposite the first direction by the 12-strand braider
system 82.
[0028] Accordingly, as shown in FIG. 8 and in more detail in FIG.
9, when the lengths of twisted sub-rope structure 74 are combined
to form the assembled sub-rope structures 84 of the rope structure
20, the pre-twist in the twisted sub-rope structures 74 is removed
by the braid twist as shown by the dashed reference lines 78 in
FIG. 8. FIG. 8 further shows that, after the inherent twist of the
12-strand braider system 82 is applied to the twisted sub-rope
structure 74, the reference lines 78 on the resulting assembled
sub-rope structures 84 define are again substantially parallel to
the longitudinal axis of the sub-rope structure 20.
[0029] Because the assembled sub-rope structures 84 are not
twisted, these sub-rope structures 84 do not deform and/or result
in deformation of the final rope structure 20. Further, the final
rope structure 20 need not be jacketed to cover the assembled
sub-rope structures 84 because the assembled sub-rope structures 84
are themselves jacketed. If the final rope structure 20 is used, as
an example, as a mooring tether or line, the assembled sub-rope
structures 84 are easily inspectable.
[0030] As shown in FIG. 10, the method of the present invention may
further comprise the step of arranging a filter member 90 between
the core structure 54 and the jacket structure 68 before or while
the jacket structure 68 is being formed. The filter member 90 may
be a long strip of filter paper wrapped in a helix around the core
structure 54 or may be a long thin sheet of filter paper folded
around the core structure 54. In either case, the filter member 90
inhibits egress of sediment and the like into the core structure
54.
[0031] The filaments 42 may be made of one or more fibers made of
the following materials: Polyester, Polyethylene, Polypropylene,
Nylon, Aramid, Liquid Crystal Polymer, copolymers, High Modulus
Polyethylene, Glass, Carbon, and Basalt.
* * * * *