Inspectable synthetic tensile member assembly

Abstract

A protected synthetic tensile member assembly including one or more fixed terminations used to transmit a tensile load from the tensile member to an external component. The tensile member includes access for inspection of its constituent fibers in at least one selected inspection region. The region is selected on the basis of the area of interest to the tensile member's use—such as the area of greatest stress concentration or the area of greatest abrasion. A removable cover is provided for the inspection region. A user may selectively remove this cover in order to gain access to the inspection region.

Claims

1. A method for providing and inspecting a durable yet inspectable tensile member assembly including synthetic fibers as a primary tension-carrying element, comprising: a. providing a core of synthetic fibers, said core having an end; b. attaching a termination to said end of said core, said termination including an anchor with a length of said fibers secured thereto and an anchor exit where said fibers exit said anchor; c. wherein said anchor includes an internal passage and said length of said fibers lie within said internal passage, with said fibers being locked into a solidified potting compound, with said anchor completely surrounding said length of said fibers; d. providing a jacket surrounding said core and extending along said core to a jacket end, with said jacket lying outside said anchor and said jacket end lying proximate said anchor exit, thereby leaving a gap between said jacket end and said anchor exit; e. said core of synthetic fibers being accessible within said gap, said gap thereby comprising an inspection region; f. providing a first cover configured to cover a first portion of said inspection region, said first cover being attached to said anchor and overlapping said jacket so as to cover said first portion of said inspection region; g. providing a second cover configured to cover a second portion of said inspection region, said second cover configured to attach to said anchor and to overlap said jacket so as to cover said second portion of said inspection region, said first and second covers in combination covering all of said inspection region; h. providing a fastener configured to attach said second cover to said first cover; i. removing said first cover from said anchor and said jacket to permit inspection of said core within said inspection region; and j. following said inspection of said core within said inspection region, reattaching said first cover to said anchor and said jacket.

2. The method for providing and inspecting a durable yet inspectable tensile member assembly as recited in claim 1, wherein: a. said first cover is attached to said anchor by a first mechanical interlock; and b. said first cover is attached to said jacket by a second mechanical interlock.

3. The method for providing and inspecting a durable yet inspectable tensile member assembly as recited in claim 1, wherein said first and second covers are configured to clamp over said anchor, said inspection region, and said jacket end.

4. The method for providing a durable yet inspectable tensile member assembly as recited in claim 1, wherein: a. said anchor includes an anchor ring; b. said jacket end includes a jacket ring; c. said first cover includes an anchor ring receiver configured to receive and engage said anchor ring on said anchor; and d. said first cover includes a jacket ring receiver configured to receive and engage said jacket ring on said end of said jacket.

5. The method for providing a durable yet inspectable tensile member assembly as recited in claim 4, wherein: a. said second cover includes an anchor ring receiver configured to receive and engage said anchor ring on said anchor; and d. said second cover includes a jacket ring receiver configured to receive and engage said jacket ring on said end of said jacket.

6. The method for providing a durable yet inspectable tensile member assembly as recited in claim 3, wherein: a. said anchor includes an anchor ring; b. said jacket end includes a jacket ring; c. said first cover includes an anchor ring receiver configured to receive and engage said anchor ring on said anchor; and d. said first cover includes a jacket ring receiver configured to receive and engage said jacket ring on said end of said jacket.

7. The method for providing a durable yet inspectable tensile member assembly as recited in claim 6, wherein: a. said second cover includes an anchor ring receiver configured to receive and engage said anchor ring on said anchor; and b. said second cover includes a jacket ring receiver configured to receive and engage said jacket ring on said end of said jacket.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

(1) FIG. 1 is a perspective view, showing a prior art tensile member.

(2) FIG. 2 is a sectional elevation view, showing the assembly of FIG. 1.

(3) FIG. 3 is an exploded perspective view, showing an embodiment of the present invention.

(4) FIG. 4 is a sectional elevation view, showing the assembly of FIG. 3.

(5) FIG. 5 is an elevation view, showing some details of the assembly of FIG. 3.

(6) FIG. 6 is a sectional elevation view, showing an additional embodiment of the invention.

(7) FIG. 7 is a sectional elevation view, showing still another embodiment of the present invention.

(8) FIG. 8 is a perspective view, showing the embodiment of FIG. 7.

(9) FIG. 9 is a sectional elevation view, showing still another embodiment of the present invention.

(10) FIG. 10 is a perspective view, showing the use of a alignment marking on a tensile member jacket.

(11) FIG. 11 is a sectional detailed view, showing the use of a jacket having layers with differing colors.

(12) FIG. 12 is an elevation view, showing the application of the present invention to a sling device.

(13) FIG. 13 is an exploded perspective view, showing an inspection region and cover for a sling device.

(14) FIG. 14 is an exploded perspective view, showing an alternate embodiment of the inspection region on a sling device.

(15) FIG. 15 is a sectional elevation view, showing a termination including two removable covers.

REFERENCE NUMERALS IN THE DRAWINGS

(16) 18 anchor 20 tensile member 22 termination 24 jacket 26 fibers 28 jacket receiver 30 expanding passage 32 potted region 34 threaded coupling 36 attachment fixture 38 removable cover half 40 removable cover half 42 cap screw 44 receiver 46 jacket ring 48 anchor ring 50 access hole 52 inspection region 54 anchor ring receiver 56 jacket ring receiver 58 anchor opening 60 tensile member opening 62 transparent sling 64 threaded cover 66 shoulder 68 threaded engagement 70 cover 72 access port 74 alignment marking 76 outer layer 78 inner layer 80 wound sling 82 stirrup 84 tension member 86 casement 88 cover 90 strap 92 snap 94 receiver 96 pin receiver 98 first flange 100 second flange 102 threaded boss 104 thimble 106 neck anchor portion 108 distal anchor portion 110 threaded engagement

DETAILED DESCRIPTION OF THE INVENTION

(17) Synthetic tensile member assemblies are used in a wide variety of applications, each of which imposes differing operating constraints. The operating constraints of a particular tensile member will often determine the areas of interest for inspection. For instance, a tensile member that is carrying a relatively static tensile load with potted terminations (such as a crane boom pendant) often has the greatest stress concentration and bending fatigue at the point where the freely flexing fibers in the tensile member join the potted region in the anchor (the “potting interface”). The fibers will generally start to break in this location when the tensile member begins to fail. Thus, it is advisable to define an “inspection region” for such a tensile member in the vicinity of the potting interface.

(18) On the other hand, another tensile member might pass over a pulley near its mid point. That point might then warrant inspection and it would make sense to define an “inspection region” near the tensile member's midpoint. In general, the present invention operates by:

(19) (1) Providing a synthetic tensile member that is protected by a jacket;

(20) (2) Providing the synthetic tensile member with at least one pre-defined load-transference point (a fixed termination) that defines a consistent and controlled point where a load is transferred from the synthetic tensile member to some external object;

(21) (3) Defining one or more inspection regions where a user wishes to be able to examine the fibers of the tensile member (either visually or by other means); and

(22) (4) providing a removable cover that selectively covers the defined inspection region(s).

(23) When in place, the removable cover preferably provides suitable protection for the fibers it covers. It is also desirable for the removable cover to be removable and replaceable multiple times over the useful life of the tensile member (though an individual cover may need to be replaced by a new cover). These objectives may be achieved using a wide variety of physical components. In the following paragraphs, detailed descriptions are provided for some of the invention's embodiments.

(24) FIGS. 3-5 disclose the first embodiment of the present invention. FIG. 3 shows how jacket 24 stops short of anchor 18 in this version, leaving a length of exposed synthetic fibers therebetween. The length of exposed fibers is the “inspection region” for this embodiment. In this embodiment the removable cover is split into two halves 38, 40. These may be joined together by any suitable means. In the example shown, six cap screws are fed through access holes 50 on one of the removable halves and then threaded into threaded receivers 44 on the other half. Each access hole includes a countersunk shoulder for the head of the cap screw to bear against and draw the two halves tightly together.

(25) It is important to protect the interior fibers from harmful exposures during use. Therefore, in this embodiment, a positive lock is provided between the cover and the jacket. This may be done using many different features, such as a long clamping surface, or a series of interlocking features. One could also include one or more sealing O-rings. One could also introduce an injected sealing compound—such as a curable silicone—before clamping the two cover halves together.

(26) In the example of FIG. 3, anchor 18 is equipped with one or more anchor rings 48. Likewise jacket 24 may include an integral or separate jacket ring 46. The two removable cover halves include annular recesses that are sized to receive and engage the anchor rings and jacket ring.

(27) FIG. 4 shows a sectional view through the assembly of FIG. 3 with one of the two removable cover halves still in place. Inspection region 52 in this embodiment is the annular region between the end of the jacket and the start of the anchor. For a tensile loading—especially with some flexure—the area of maximum stress concentration will often occur near the interface between potted region 32 and the freely flexing fibers within the balance of the tensile member.

(28) Another area where inspection may be desired is the point at which the fibers exit the rigid anchor. Mild flexing will often occur at this point, producing fatigue. Thus, when the tensile member is overloaded or has experienced too much cyclic bending, the fibers in one of these regions will tend to break down before the balance of the fibers in the tensile member. Inspection region 52 allows visualization of the fibers proximate the potted region interface.

(29) FIG. 5 is a non-sectional view showing one of the cover halves lying next to the tensile member assembly. Removable cover half 40 in this example includes:

(30) (1) anchor opening 58 sized to admit anchor 18;

(31) (2) anchor ring receivers 54 sized to receive and engage anchor rings 48;

(32) (3) jacket ring receiver 56 sized to receive and engage jacket ring 46; and

(33) (4) tensile member opening 60 sized to admit jacket 24.

(34) Jacket ring 46 may be forms by depositing additional material over jacket 24. It may also be formed by ultrasonically deforming the end portion of the jacket to create a “bead.” In still other instances the jacket ring may be a separate piece that is joined to the balance of the jacket by an adhesive or by simple friction. In some instances, however, it may be preferable to omit jacket ring 46 altogether. In that case, the interior of the removable covers may simply incorporate gripping features—such as a knurled surface or annular ring recesses—configured to “bite” into the jacket. Other gripping features may also be substituted for the interface between the removable cover half and the anchor. A connection between the cover and the jacket may also be created using a separate adhesive.

(35) For purposes of this invention, it is only important that the jacket be held in place with a reasonable seal in order to prevent the ingress of unwanted factors based on the particular application. The unwanted factors could be UV light, chemicals, dirt, or other identified factors. The jacket, and its interface with the tension member, its interface with the termination(s), and its interface with any removable cover should be designed to provide an appropriate level of durability for the intended use.

(36) FIG. 6 shows a variation on the embodiment of FIG. 5. In FIG. 6, inspection region 52 is covered by a transparent sleeve 62. In this version, the transparent sleeve remains in position after the cover halves have been removed. However, the user is able to visually discern damaged or broken fibers through the transparent sleeve. The region of transparency may be a smaller window within a larger sleeve. The use of such a transparent region could be adopted to different portions of the anchor or jacket as well.

(37) FIGS. 7 and 8 disclose an additional embodiment that uses a different approach to attaching and removing the cover. Threaded cover 64 is a sleeve that selectively connects to anchor 18 via threaded engagement 68. The distal end of the threaded cover includes shoulder 66, which is sized to bear against jacket ring 46. When the user wishes to inspect the inspection region, he or she grasps threaded cover 64 and unscrews it. Once the threaded engagement is released the user is able to slide the threaded cover down the jacket.

(38) This type of cover provides good access to a useful inspection, point. Stress is generally concentrated in the neck region of the anchor. This is true for a potted termination (such as shown) and also for spike-and-cone terminations, other compression devices, and nearly any other form of fixed termination. It is also useful to inspect such a transition region in the case of a spliced thimble where high stresses, abrasion, misalignment, or undesirable fiber-to-fiber slipping may occur.

(39) This action is shown in FIG. 8. Threaded cover 64 is pulled down tensile member 20 in the direction indicated by the arrow. This motion reveals inspection region 52. When the inspection is complete, the user pushes the threaded cover back into engagement with the threads on anchor 18 and tightens it.

(40) Those skilled in the art will appreciate that many other configurations for the inspection regions and covers are possible. The design of these components is dependent on the tension member construction, the location and size of the desired inspection regions, and the level of durability required to manage the unwanted elements.

(41) FIGS. 9-14 serve to illustrate a few of these possible additional embodiments. FIG. 9 shows an embodiment in which the inspection regions are accessed through the anchor itself. Anchor 18 is provided with one or more access ports 72. Each access port is threaded in order to receive a cover 70 (which is also threaded). When a cover 70 is removed, a user may visually inspect the synthetic fibers in inspection region 52. It is also possible to provide transparent windows in the anchor itself.

(42) The cover in this example could even be an injected volume of curable silicone. The silicone would be injected as a liquid and then cure to form a pliable solid. The resulting flexible plug could be pried out with a screwdriver when inspection is needed. It would then be “replaced” by injecting a new volume of silicone.

(43) As still more examples, the cover could span a large region and be removed by pivoting or sliding. The cover would be “removed” to permit access to the inspection region, yet would remain attached to the balance of the tension member.

(44) It is preferable to combine other stress-indicating features with the provision of the covered and protected inspection region. FIGS. 10 and 11 illustrate some of these features. FIG. 10 shows a termination 22 that incorporates a clevis joint configured to receive a pin through a transverse hole. Several overload holes 104 are provided in the region of the transverse hole. If a maximum specified tensile load is exceeded, overload holes 104 allow the transverse hole to elongate. This action tends to “clench” the pin that is passing through the hole. The metal will also be visibly deformed. These conditions will alert the user to the fact that the tensile member has been overloaded and should be removed from service.

(45) Also, since the protection tensile member is covered, it may be important to control certain movements that could go unnoticed and that might adversely affect strength. In many synthetic fiber constructions, it is important to ensure that the tension member is not significantly twisted. Alignment marking 74 may be added to the tensile member jacket to show any significant twist. The alignment marking is preferably of a contrasting color—such as a yellow alignment marking on a black background. It may also be desirable to rotationally interlock the jacket and the core of synthetic fibers it contains. An extruded jacket may include a protrusion that extends inward into the core. The protrusion in the extruded profile creates a longitudinal rib that inhibits any rotation of the jacket with respect to the core. Of course, there are many possible alignment markers that could be used continuously or at certain intervals along the tensile member. Even printed text could be used for this purpose.

(46) It is also preferable for the jacket to visually indicate a significant form of wear—such as burns, cuts, scrapes, scuffs, or a full breach. FIG. 11 shows one approach to providing such a feature. Jacket 24 includes two layers—outer layer 76 and inner layer 78. The two layers may be provided in contrasting colors (possibly using different materials). For example, the outer layer may be black while the inner layer is yellow. A scuff that is deep enough to penetrate the outer layer will thereby appear as a yellow streak on the black jacket. The outer layer may also be designed for a certain type of protection (cut resistance) while the inner layer might be designed for a different type of protection (moisture resistance).

(47) Such a multi-layer jacket construction provides a visual “go/no-go” indication for the tensile member assembly. Separate retirement or repair criteria could then be applied to each layer of the jacket.

(48) The preceding embodiments have included terminations where a length of fibers is potted into an anchor. In the field of synthetic tension member, there are of course other types of terminations and the invention is by no means limited to ropes or cables with anchor-based terminations. FIGS. 12-14 provide illustrations of the invention applied to other types of tension members and terminations.

(49) One way to create a termination is to pass a braided rope around a stiff thimble or sheave and then weave it back into itself. A transverse pin is then passed through the thimble or sheave to convey a load. In some cases this may be configured with one tensile leg, and in other cases the synthetic fibers may wrap back around to form a “grommet” (circular configuration) with two or more tensile legs and a fixed termination at each end. In the case where grommets or round slings are used, it is important for purposes of this invention that some form of fixed termination be used. This allows the stress to be controlled and located at a defined point during the use of the tensile member.

(50) FIG. 12 shows still another type of tensile member and termination. In this version a very long fiber or a series of twisted yarns or ropes is passed repeatedly around the two stirrups 82 until a thick bundle is produced. The entire assembly is then sealed into casement 86 (which may be a urethane or a two-part epoxy that is hardened in situ after the assembly is placed in a mold). The result is tension member 84 passing between the two stirrups 86. Such an assembly is thereby entirely sealed, with the end terminations sealed to the center region and a protective jacket covering all the fibers.

(51) FIG. 13 shows the inclusion of an inspection region 52 on the outside portion of a stirrup 82. The inspection region is an opening in the casement that reveals the fibers inside in an area where stresses are concentrated. Cover 88 is selectively placed over the inspection region when no inspection is desired. Cover 88 is secured using strap 90. One or more snaps 92 on strap 90 snap into receiver 94. Of course, many other designs could be used to adequately cover such an arrangement.

(52) Still another approach is shown in an exploded state in FIG. 14. In this embodiment, fibers are wound around or ropes are spliced to two-sheave-type termination bodies. In this example, a transverse hole is provided through casement 86 (The casement is the protective jacket in this case). Inspection region 52 is simply the interior of this transverse hole, where stresses are concentrated. Cover 88 is a cylindrical load-bearing element that passes through the casement and covers inspection region 52. Cover 88 includes first flange 98 that bears against a first side of the casement. Second flange 100 bears against the opposite side of the casement when threaded boss 102 is threaded into a threaded receiver in cover 88. Pin receiver 96 is a smooth cylindrical hole configured to receive a linking pin that attached the stirrup to something else. Of course, many other designs could be used to provide a cover for this type of inspection region.

(53) It is preferable in this example to cover the inspection region with a transparent sleeve (configured to be a close sliding fit for cover 88). The presence of such a transparent sleeve allows the desired visual inspection without allowing the fibers within the inspection region to become disorganized and protrude into the cylindrical cavity needed to receive the cover.

(54) For a spliced rope, terminated round sling, grommet, or fiber-wound sling design, inspection of these inner bearing and sliding elements would be useful. This area, like the entry point into an anchoring or termination body, is a leading stress and wear point.

(55) FIG. 15 shows an embodiment in which an enlarged inspection region is provided. In addition, this embodiment includes two separate cover pieces that provide a progressive level of access. Threaded cover 64 is similar to the configuration shown in FIG. 7. However, in this version, the anchor has been split into two pieces—neck anchor portion 106 and distal anchor portion 108. The two anchor portions are selectively engaged via threaded engagement 110.

(56) The user may choose to unscrew threaded cover 64 and thereby gain access to the inspection region it covers. The user may then go further by unscrewing neck anchor portion 106 from distal anchor portion 108. This allows the user to extend the inspection region well into the potted region of the termination (for the case of a potted termination). In the case of a mechanical termination (such as a spike-and-cone) the extended inspection region allows the user to visualize an additional length of fibers. These transitional regions tend to carry high stress concentrations are subject to wear over use. The extended inspection region may only be used some of the time (such as to help ensure the proper initial setup of this region when it is first loaded).

(57) Additional features and variations for the present invention include the following:

(58) 1. A version where a substantial portion of the termination or the cable jacket is transparent;

(59) 2. A version where the removable cover is a piece of tape, a helical wrapping, a wire wrapping, or a painted layer; and

(60) 3. A version where each individual termination on each individual tensile member is gathered into a larger collector of terminations (in order to build a much larger tensile member, for example).

(61) Although the preceding description contains significant detail, it should not be construed as limiting the scope of the invention but rather as providing illustrations of the preferred embodiments of the invention. As an example, the removable covers could assume many different forms and could attach in different ways. Thus, the scope of the present invention should be fixed by the claims rather than the specific examples given.