EP3289136A1 - Advanced methods and designs for balancing a stranded termination assembly - Google Patents
Advanced methods and designs for balancing a stranded termination assemblyInfo
- Publication number
- EP3289136A1 EP3289136A1 EP16786864.5A EP16786864A EP3289136A1 EP 3289136 A1 EP3289136 A1 EP 3289136A1 EP 16786864 A EP16786864 A EP 16786864A EP 3289136 A1 EP3289136 A1 EP 3289136A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- strand
- cable
- collector
- preparing
- tension
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
Classifications
-
- D—TEXTILES; PAPER
- D07—ROPES; CABLES OTHER THAN ELECTRIC
- D07B—ROPES OR CABLES IN GENERAL
- D07B9/00—Binding or sealing ends, e.g. to prevent unravelling
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16G—BELTS, CABLES, OR ROPES, PREDOMINANTLY USED FOR DRIVING PURPOSES; CHAINS; FITTINGS PREDOMINANTLY USED THEREFOR
- F16G11/00—Means for fastening cables or ropes to one another or to other objects; Caps or sleeves for fixing on cables or ropes
- F16G11/02—Means for fastening cables or ropes to one another or to other objects; Caps or sleeves for fixing on cables or ropes with parts deformable to grip the cable or cables; Fastening means which engage a sleeve or the like fixed on the cable
- F16G11/025—Fastening means which engage a sleeve or the like fixed on the cable, e.g. caps
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
- E04C5/08—Members specially adapted to be used in prestressed constructions
- E04C5/12—Anchoring devices
- E04C5/122—Anchoring devices the tensile members are anchored by wedge-action
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04C—STRUCTURAL ELEMENTS; BUILDING MATERIALS
- E04C5/00—Reinforcing elements, e.g. for concrete; Auxiliary elements therefor
- E04C5/08—Members specially adapted to be used in prestressed constructions
- E04C5/12—Anchoring devices
- E04C5/127—The tensile members being made of fiber reinforced plastics
-
- E—FIXED CONSTRUCTIONS
- E04—BUILDING
- E04G—SCAFFOLDING; FORMS; SHUTTERING; BUILDING IMPLEMENTS OR AIDS, OR THEIR USE; HANDLING BUILDING MATERIALS ON THE SITE; REPAIRING, BREAKING-UP OR OTHER WORK ON EXISTING BUILDINGS
- E04G21/00—Preparing, conveying, or working-up building materials or building elements in situ; Other devices or measures for constructional work
- E04G21/12—Mounting of reinforcing inserts; Prestressing
- E04G21/121—Construction of stressing jacks
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
- F16G—BELTS, CABLES, OR ROPES, PREDOMINANTLY USED FOR DRIVING PURPOSES; CHAINS; FITTINGS PREDOMINANTLY USED THEREFOR
- F16G11/00—Means for fastening cables or ropes to one another or to other objects; Caps or sleeves for fixing on cables or ropes
- F16G11/04—Means for fastening cables or ropes to one another or to other objects; Caps or sleeves for fixing on cables or ropes with wedging action, e.g. friction clamps
- F16G11/042—Means for fastening cables or ropes to one another or to other objects; Caps or sleeves for fixing on cables or ropes with wedging action, e.g. friction clamps using solidifying liquid material forming a wedge
Definitions
- This invention- relates to the field of tensile strength members such as multi-stranded synthetic cables. More specifically, the invention comprises devices and methods for balancing the load carried by a synthetic cable among its constituent strands.
- a cable must generally be provided with one or more end connections in order to be
- An end connection allows the cable to carry and transmit a useful load.
- An end connection may be a simple device ⁇ - such as a large hook - employed to connect the. cable to an anchoring point.
- Larger synthetic cables typical !y include multiple constituent strands, it is preferable to attach an individual connective device to each strand.
- Such a connective device is referred to in this disclosure as a "strand termination. " Multiple strand terminations are
- the unified cable end connection is referred to in this disclosure as an "overall cable termination.”
- FIG. 1 shows a cable 10 made iron; advanced high-strength synthetic filaments.
- the strands may be purely parallel and encased in individual surrounding jackets. In still other examples the strands may be arranged in a "cable lay " pattern that is well known in the fabrication of wire ropes.
- the individual filaments have a thickness that is less titan that of human hair.
- the filaments are very strong in tension, but they are not very rigid. They also tend to have low surface friction. These fects make such synthetic filaments difficult to handle during the process of adding a termination and difficult to organize.
- the present invention is particularly applicable to terminations made of such high-strength synthetic filaments, for reasons which will be explained in the descriptive text to follow. While the invention could in theory be applied to older cable technologies - such as wire rope - it likely would offer little advantage and the additional time and expense of implementing the invention would not be worthwhile. Thus, the invention is not really applicable to wire rope and other similar cables made of very stiff elements.
- the cable shown in FIG. I is a. well-known exemplary construction made by braiding or otherwise interrelating twelve strands together. Polyester ropes using this construction are known to have an external diameter up to about 6 inches (see specification 1L-R-.24750). Even larger polyester ropes are made by constricting parallel sub-ropes in a braided- strand jacket.
- High-strength synthetic filaments have very little surface friction and strands made of these filaments also have very little surface friction. Thus, it is possible for one individual, strand to "slip" with respect to neighboring strands. A strand that slips tends to "unload” itself and shift the load it w s carrying to its neighbors. This is obviously an undesirable result.
- each individual strand In order to add an overall cable termination to an end of a mufti-stranded synthetic cable, each individual strand must be cot to length and have a strand termination added (It. is not essential that all strands in the cable undergo this process but -in most embodiments all strands will be involved).
- the cutting and terminating processes are inherently imperfect. The result will generally be that some terminated strands will wind up being longer than desired while others will wind up being shorter then desired. If a tensile load is placed on the cable with no accommodation tor these manufacturing tolerances, the relatively "short " strands will be loaded first and they will carry moi « load than the relatively long strands.
- FIG. 2 shows a section view through, a strand termination 30 that has been added to the
- FIG, 2 shows a sectional view through the components used to create the termination.
- anchor 18 includes an expanding cavity 20 that expands as one proceeds from the portion of the anchor facing the length of cable (the "proximal” end, which is 90 the bottom end in the orientation of the view) toward the portion of the anchor facing in the opposite direction ⁇ the "distal" end, which is the top end in the orientation of the view).
- the expanding cavity in this example is a linear taper between two straight portions - all joined by fillets. Differing wall profiles may be used to create a wide variety of expanding cavities.
- the end ' portion of strand 12 is potted into the expanding cavity in order to lock anchor 95 1 to strand 12.
- the filaments of the strand are splayed apart and infused with liquid -potting compound (either before or after being placed within expanding cavity 22).
- the liquid potting compound may be added by a variety of methods, including: (!) "painting " or otherwise wetting the filaments with potting compound and then sliding the anchor into position over the painted filaments, (2) positioning the splayed filaments in the cavity and then pouring in pelting 100 compound, (3) pre- etting, the filaments in a separate mold designed to wet the filaments, and (4) injecting pressurized potting compound into the cavity.
- the potting compound is introduced, the splayed filaments remain within cavity 20 while the potting compound hardens. Once it has hardened the result is a mechanical interlock between the figment-reinforced "plug" (contained in potted region 22) of solid material and the cavity. Tension applied to the cable will i OS thereby be transmitted to the strand.
- the potting compound used is typically a high-strength resin.
- potting compound as used in this description means any substance which transitions from a liquid to a solid over time.
- the present invention is applicable to any method of " creating a termination or, the end of a synthetic filament tensile member.
- S potted examples are shown in these descriptions the invention is not limited to that approach, and the -reader should understand the term “strand termination” to broadly encompass all methods of attaching a device to the end of a strand.
- FIG. 2 shows additional components that are added to facilitate the gathering of multiple strands into a single, load-transferring element in the example shown, loading stud 24 has been0 connected to anchor I S via threaded engagement 28.
- Loading stud 24 includes male thread 26 over a significant length (The threads are shown, schematically but are not actually depicted for purposes of visual clarity). This threaded stud allows the completed assembly to be attached to other things to ultimately create an overall cable termination.
- the anchor simply be a cylinder with a load-hearing flange facing downward in the orientation of FIG. 2.
- connection between the cylinder and another object could then be placing the load-bearing flange against another surface.
- FIG. 3 shows the cable after an identical (in this example) strand termination 30 has been added to the end of each strand 12,
- the reader will observe how a length of each strand is preferably unhraided from the cable structure so that a free length exists proximate the termination. This allows each strand to be manipulated so that it may be attached to another device.
- a separate device or devices is used to aggregate all the individual strands and strand terminations to a unified load-transferring assembly. This unified assembly will be referred to as an "overall cable termt nation" in order to distinguish it from the individual "strand- terminations"5 applied to each strand.
- the design of the strand terminations, the overall cable- termination, and the unifying devices employed to create the overall cable termination can take on many and various forms. The present invention is applicable to all of these forms.
- the present invention bads the cable .in a controlled, and carefully designed manner resulting In a reduction in misalignments and a more evenly distributed load among the cable's constituent strands.
- cables will be used as an example of a tensile strength member.
- the terra "tensile strength member” or “tensil member” encompasses cables and sub-components of cables such as strands.
- the invention also encompasses non-cable structures intended to carry loads in tension.
- anchor should be viewed broadly to encompass virtually anything thai can be attached to a strand or cable.
- the anchor would ordinarily include some features fec i I statin g attachment - such as a hook or threads,
- the present invention comprises devices and methods for loading a cable in order to create a desired distribution of the load mon the cable's constituent strands.
- Strand terminations are applied to many - and possibly all of- the cable's strands.
- the ultimate goal is to connect the strand terminations to a collector i order to create an overall cable termination.
- the relationship between each strand termination and the colleetor is allowed to "float" using the inventive process while the cable is tensioned and an appropriate spatial relationship between each strand tensioner and the collector is determined.
- One the appropriate relationship is found, it is configured to be repeatafale (such as by locking the strand termination in place or by recording its position for later application to the same or similar collector).
- a strand tensioner is provided for each individual strand termination. Tension is applied to the cable through the strand tensioners. Tension may be
- FIG, 1 is an elevati n view, showing the braided structure of an exemplary 12 -strand cable.
- FIG, 2 is .a sectional sectional view, showin a termination created on the end of a single cable strand.
- FIG. 3 is a perspective view, showing 12 terminations attached to 12 strands in an 175 exemplary cable.
- FIG. 4 is a perspective view, Showing a collector used to assemble Ihe 12 terminations of
- PIG. 5 is a sectional perspective view, showing an exemplary attachment between a termination and a collector.
- FIG. 6 is a perspective view, showing all ! 2 terminations attached to the collector.
- F IG, 7 is a perspective view, showing a particular type of strand tensioner.
- FIG, 8 is a side elevation view, showing an assembly used to apply loads to ail the strands in a cable assembly in a controlled fashion.
- FIG, 9 is a plot of strand displacement and applied tension over time.
- FIG. 10 is a plot of strand displacement and applied tension over time.
- FIG. 1 1 is. a plot of strand displacement and applied tension over time.
- FIG. 12 is a plot of strand displacement over lime for multiple strands.
- FIG. 12 is a side elevation view, showing an assembly used to apply loads to all the strands in a cable assembly in a controlled fashion.
- FIG. 14 is a detailed perspective view, showing a rotation-limiting feature.
- FIG, 1 S is a detailed perspective view, showing an alternate embodiment for a strand tensioner.
- FIG, 16 is a detailed perspective view, showing an alternate embodiment for a strand
- FIG. 4 shows an exemplary device used to gather all the strands into a unified whole and thereby create m overall cable termination.
- Collector 34 includes twelve receivers 3S, each of which is configured to connect to a single strand termination (In other embodiments a receiver may be configured to connect to m ltiple strand terminations),
- Coflector 3-4 typically includes some type of load-transferring feature designed to transfer a load from the collector to some external element.
- Loadin flange 36 is a simple example of a load-transfemng feature, The
- FI 3. 5 ' shows an exemplary connection between a (semination on a strand arid the collector.
- Loading stud 24 is passed through opening 46 and through receiver 38 m collector 34.
- Receiver 38 includes a hemispherical concave portion sized to accept, hemi bearing 44, He-mi bearing 44 and receiver 38 form a ball-and-socket connection thai allows the termination to f late with respect to collector 34.
- collector 34 is ordinarily placed in a loading fixture that holds it in position.
- the far end of the cable to which the strand belongs is likewise held in place (such as by winding it around a capstan or some other means, such as applying an overall cable termination to the far end). A substantial tensile load is then applied to the cable as a whole.
- FIG, 6 shows n assembly of collector 34 and all twelve strands.
- the reader will observe that twelve loading studs 24 are i position and a nut 40 is connected to each stud (The loading studs 24 shown in FIG. 6 are longer than depicted in FIG. 5 in order to give art additional x3 ⁇ 4nge of adjustment. Also - the threads on the exterior surface of the loading studs are again omitted for purposes of visual clarity).
- This view illustrates the advantage of including a ball-and-socket connection in some of the embodiments. As each strand emerges from the cable's braided construction it assumes a particular angle with respect to the collector. Some diverge more than
- a tensile load from two or more strand terminations may be a unified piece as shown but may also be an assembly of multiple pieces. Further, a "stand-in " collector may be used to pre-load the cable and adjust each of the strand terminations (as described subsequently) and the strand terminations may ultimately be connected to an entirely different collector.
- the pre-load process might appl a tension to the cable that is equal to 100% or even as much as 150% of the expected
- the present invention seeks to preload the cable at the strand level and manipulate the strand termination to collector connections in order to create a desired apportionment of the overall load among the constituent strands. Without careful preloading a large cable assembly will very likely have an uneven distribution of
- the present invention -obtains advantages by individually applying tension to the strands so a large, multi-stranded cable.
- Collector 34 is held within fixture 58 during the tensioning process. Significantly, however, it is not generally used to apply any tension to the cable strands during the pre-loading process. During the process, each individual strand iennin&tion is allowed to float with respect to collector 34. ' Tension to the cable is actually applied directly through the strand -terminations themselves (as will he described subsequently). As tension is applied, the inventive components operate to apportion the overall load among the individual strands in a predetermined arrangement (usually this will be an equal load applied to each strand but there are exceptions).
- each strand termination and the collector is established (such as by ' locking the strand termination, to the collector in the desired position or by recording the desired position .so that it can later be reestablished).
- collector 34, fixture 58, space frames 66, fixture 64, and all the connected components move in unison. ' This entire assembly may slide within a larger frame or otherwise be stabilized.
- one or more hydraulic cylinders 72 connect primary load fixture 70 to -attachment 74 on the moving assembly.
- the right, side of the one or more hydraulic cylinders 72 (in the orientation of the view) is fixed to a substantial and stationary anchor point.
- the moving assembly (along with collector 34) Is urged to the right in the view. This action applies tension to cable 10 (since the far end of the cable is held).
- the frame structures shown are preferably very stout so that a large tensile load may be applied. For some cables it may be desirable to provide a tensile load of I million pounds or more,
- each individual strand must be cut to length and have a strand termination added to its free end.
- the manufacturing tolerances of both the cutting operation and the termination operator ean only go so tar.
- Some of the strands will wind up being shorter than designed and others will wind up being longer than designed.
- the shorter strands will carry most of the ad and the longer strands may in fact carry very little. For this reason, it is desirable to be able to adjust the -position of each of the strand terminations with respect to the collector.
- each strand termination and the collector include an adjustment feature.
- the adjustment feature in the embodiment of FIG, 6 is the nut 40 placed on each loading stud 24. These nuts can- be tightened manually to provide the desired adjustment.
- each loading stud on each individual strand is attached to a strand tensioner 50, All the strand tensioriers are attached to fixture 64.
- the moving assembly is moved to the right under the force imparted by the one or more hydraulic cylinders 72, it is the strand terssionets (.50) (in this particular embodiment) that actually apply the tension to the cable.
- the loading stud on each strand passes through the collector but should not transfer any significant forces to the collector, instead, the loading stud is attached to i ts respective strand tensioner 50.
- FIG. 7 shows an exemplary strand tensioner 50.
- This particular strand tensioner includes a hydraulic cylinder 52 with an extending retracting rod 56.
- Coupler 48 is provided on the free end of the rod.
- the coupler in this example includes a female threaded hole configured to engage an individual loading s ud 24. The coupler is threaded over the loading stud and a
- strand pensioner may include hooks, brackets, and m ny oilier types of devices.
- the rotation limiting device prevents rotation between coupler- 48 and loading stud 24 once the coupler is firmly attached- to the loading stud. It is also preferable to limit rotation between rod 56 and cylinder 52. A key way may be used to rotationaliy lock the rod and cylinder together.
- Mount 54 is provided to attach strand iensioner 50 to an external frame. One or more pivots may be provided on mount 54 so that the angle of strand tensioner SO ma be made adjustable. Appropriate hydraulic connections are provided so that hydraulic pressure may be used to extend and retract rod 56 - if desired.
- strand tens! oners 50 could be viewed as ''passive ' " devices.
- the hydraulic lines leading from each strand tensioner .50 are fed into a common, pressurized reservoir.
- the reservoir can be contained within pressure comroiler/sensor 60 (see F!G. 13).
- the hydraulic cylinders within each strand tensioner 50 are double-acting cylinders ibr this example.
- the piston within each of these double-acting cylinders is preferably placed near the mid-poi nt of its range of travel (midway between the two illustrated fluid pons).
- displacement sensor 64 may he provided to monitor the motion of the rod during the tensioning process.
- the tension actually being applied can he monitored by monitoring the hydraulic pressure applied to the cylinder.
- fixtur 64 must provide
- strand tensioner to be adjusted as desired, though some embodiments may include fixed positions.
- the result in this exam le is a radial pattern of diverging strand tenslcmers.
- space frames 66 are positioned to keep fixtures 58 and 64 in position so that the substantia! tensile forces applied to the strands do not distort the assembly,
- the strand tensioners may be remotely located, with the connection to the strand terminations being made with cables passing over pulleys.
- Other embodiments might use levers or other remote-mounting mechanisms.
- the construction shown is properly viewed as exemplary.
- Pressure controller/sensor 60 provides hydraulic pressure to each of the twelve strand tensioners. In many instances the same pressure will be fed to all tenssoners, since this will ultimately produce a uniform tension among the strands. If a common pressure is desired, the prior example of simply plumbing all the retract ports on ail the cylinders within strand tensioners 50 to a -common, pressurized reservoir may be used. However,, in other instances it will, be desirable to vary the pressure applied to each tensioner. Thus, pressure controller 60 may he configured to independently apply pressure to each cylinder and to monitor and maintain a selected pressure for each cylinder. This may be desirable tor cable lay constructions, where a higher tension may he applied to the inner strands than the outer strands.
- Proces controller 62 preferably receives information regarding the translation of each cable strand (via. an input such as displacement sensor 64 ⁇ and the tension applied to each strand.
- Strand tension may be derived from the pressure applied to each strand tensi ' oner or via some other source - such as a load cell or strain gage placed on the strand termination or on the strand tensioner,
- pressure would be applied to one or more hydraulic cylinders 72 to pull the slack oat of the cable and apply Increasing tension. Hydraulic pressure will then be created -within the strand tensioners 50 as the load is transferred from
- t e relative position be ween each strand termination and the collector should be locked in place so that the strands don't shift significantly when the pre-load is removed.
- Any suitable locking mechanism can be used. For the example of FIG, 6, one would simply appl a uniform amount of torqu to each of the nuts 40 while the strand tensioners 50 maintain tension on the strands.
- the invention seeks to preserve the proper spatial relationship between each strand termination and the collector, so that the proper relatio ship can be recreated when the cable is put into use.
- One way to preserve this relationship is mechanically locking the strand terminations in the position determined to be correct during the preloading process.
- the correct spatial relationship would be recreated by adjusting each strand termination until it repeated the previously taken measurements. This could he done with the same collector used in the pre-load process. It could also be done with another substitute collector.
- the collector used in ' the pre-load process might be a modular assembly intended only for the taking of accurate measurements and not for Held use. It might .be equipped with expensive position sensors that one would not wish to install in the field.
- cables using synthetic filaments tend to have relatively little surface friction.
- one strand to slip relative to the others in a direction that is roughly parallel to the cable's central axis (a "longitudinal slip"). Once such a slip occurs it is difficult to detect and in many instances
- the region where the strands transition from the free cable structure to the collector should stay reasonably balanced.
- the goal is primarily the prevention of a slip. The approach is to carefully control and regulate the tension applied to each individual strand so that: no significant imbalance occurs. In the absence of an imbalance a slip is unlikely.
- Consistency and repeatability are very important in the cable industry - ⁇ particularly where the cables carry large loads.
- the present -invention seeks to pre-load the cable and adjust each strand termination to the appropriate spatial relationship with the collector without producing a longitudinal slip, in a closed-loop embodiment strand tension and/or position can be monitored and fed to a process controller that automatically adjusts the tension applied to each strand.
- the loading process is preferably modified in real time in the event that unwanted slippage is detected.
- a strand tensioner SO (as described previously) is provided for each strand in a cable.
- FIG. 13 illustrates one possible fixturing arrangement.
- the reader w ll recall that collector 34 is simply held in plsce during the 0 tensioning process.
- the strands pass through the collector but should not transfer any significant forces to the collector as the strand ienstoners go to work.
- Process controller 62 preferably receives information regarding the translation of each cable strand (via an input such as displacement sensor 64 ⁇ and the tension applied to each strand.
- Strand tension may be derived from the pressure applied to each hydraulic cylinder or via some other source - such as a load S cell or strain gage placed on the strand termination or on the strand teasioner.
- process controller 62 ideally includes a processor running a control program. This allows a prescribed "ramp up" of strand tension.
- the process need riot be a fixed one but is more preferably an adaptive process that changes according to the sensor values.
- FIGs. 9 - 12 illustrate several examples of operation for the0 device of FIG. 8. The reader should bear in mind, however, thai the operational configurations are virtually limitless and so the examples provided should .not be : viewed as limiting,
- PIG. 9 shows an example where tension is steadily raised on all strands at the same time (though only a single strand is plotted).
- the upper plot shows the linear displacement of the termination affixed to "Strand 1."
- the lower plot shows the tension applied to the same "Strand5 I . "
- the first part of the curve is non-linear and represents the initial removal of slack.
- FIG. 9 represents an "open loop” scenario where tension is ramped up at a fixed rate and no slip detection is included.
- FIG, 10 illustrates this scenario.
- controller 62 detects the onset, of a potentially damaging slip.
- the controller immediately reduces the applied tension on Strand 1 (see lower plot) so that a smooth displacement is .maintained.
- Tension continues to be ramped up on the other strands within the cable. The increase in tension on the other strands will tend to w re-clench" the previously slipping Strand I (recall the complex braided structure shown in PIG, I ).
- tension on Strand 1 is ramped back up (shown as Points B and .8 '* ). A normal increase is then continued unless another slip is detected.
- a slip may occur so quickl that the tensioning apparatus cannot respond rapidly enough, in those cases the best approach will be to regulate the tension applied to each strand in such a fashion as to prevent the sli to begin with. If the displacement sensors then detect a slip, this information may still be useful because it informs the operator that the
- FIG, 11 shows a plot depicting this type of "ramp up.” Agai , the plot shows only one strand in a 12-strand cable, but the plots for the other eleven strands would be similar (in the absence of a slip). Slack is removed and tension is ramped up until Point A. Tension is then stepped, down to a low level and a low-tension interval (from Point A to Point B) is maintained so that the cable structure can stabilize.
- FIG. 12 shows a combined plot f displacement versus time for all twelve s trands in a 1 - strand braided cable.
- the process controller typically measures and compares the values for all the cable strands as the tensioning process proceeds.
- Another effective slip detection method is to "scan" for one strand passing too far outside the average for all the strands.
- one strand (Strand 3) has experienced a substantial longitudinal slip and its displacement has suddenly progressed rapidly beyond that of the other strands.
- the controller can reduce the tension on Strand 3 and allow the cable to stabilize as the tension on the other strands is inc reased.
- FIG, 8 shows a simplified alternate tensioning fixture.
- fixture 58 and fixture. 64 are stationary.
- Tension is applied, to the far end of the cable using another fixture, or some other means such, as by rotating & capstan around which the cable is wound.
- the tension on the individual strands is regulated and adjusted using the individual strand tensloners 50.
- t may be regulated, via connecting them to a common, pressurized .reservoir, or via an active control approach.
- FIG. 16 shows telescoping clevis 90 in an activated state, it engages the two .fiats 92 and prevents the rotatio of loading stud 24, In this configuration, the gear drive within
- strand tens.bn.er 88 rotates nut 44 and thereby increases or decreases the tension on the strand to which loading stud 24 is attached.
- the control of strand tenskmer 88 may be manual.
- strand tension 88 may be substituted tor strand tensioner 50 in the embodiment of FIG . 13. In that ease, strand tensioner 88 could be controlled by process controller 62.
- FIG. 17 illustrates a substitute sensing method that could be used tor virtually any
- the conventional washer between nut 40 and collector 34 has been replaced by toad cell 94.
- This ad cell is provided with -wiring 96 to connect it to a remote sensor monitor or possibly the process controller itself.
- the tension or! each strand may be monitored,
- the wired connection could be replaced by a wireless one having an internal battery with enough energy to last through the preloading process, ft could even be
- 600 made rechargeable in order to be useful for load monitoring in the field.
- the displacement sensor on the hydraulic cylinders could be replaced by an optical system thai uses light to measure the displacement of each loading stud;
- the pressure sensors in the hydraulic system could be replaced with direct load sensors—such as load cells or strai gages;
- Pulsed hydraulic force could be applied to the tensioning process rather than a
- the strand tensioners are then released and the cable can be removed from the fixture and prepared for use.
- the nuts may be secured in position using other device such a a cottar key, tack welding, or any other suitable method. If desired, the protruding length of loading stud 24 can be removed at that lime.
- the tightening of the nuts may be done by automated machinery, since it is .generally0 undesirable for a human operator to come near the collector assembly while the strand tensioners are maintaining tension.
- the amount of force applied is such thai a component failure could produce a -dangerous condition.
- a shim of suitable thickness could be placed between a portion of the ioading stud and the collector. It is also, desirable in some circumstances to clamp the collector from the underside (in the perspective of FIG. 5). A separate, shim or fastener can be used for this nurmvse.
- T his includes cables having a braided construction, or cable lay construction, it also includes cables made using simple helical twists, as well as other constructions. Such cables are said to have an Interwoven structure.
- the load-balancing aspects of the invention are potentially useful tor all synthetic cables, including those with a purely parallel construction built with parallel strands encased in a wound external jacket.
- the invention is also applicable to virtually any defined tensioning plan.
- the example of FIGs. 10 and J I are only two amon the virtually endless possibilities, Many of the inventive embodiments monitor the amount of tension being applied in the cable through indirect means. An example of this is using the pressure applied to the hydraulic cylinder in the example of FIG. 8. One may easily calculate the applied tension by knowing the pressure. On the other hand, one may simply use pressure as a good proxy for applied tension and base the eontroUing algorithms directly o pressure.
- Process controller 62 preferably ' includes a processor running software that can accommodate these and other variations.
- spatial relationship will be understood to meari the relative position of strand termination with respect to the collector, in some instances this may be a single linear dimension. Looking at the example of FIG. 6, if one omits a ball-and-socket connection and simply passes the loading studs 24 through holes in the collector 34, then adjusting the nuts 40 will adjust one. linear dimension, in other examples, however, there may be more than one degree of freedom involved.
- the collector could be an assembly of muhiple pieces that are not joined until the cable is put into use;
- tension monitoring for each strand could be via a wireless transmission torn a load cell mounted in each receiver.
Abstract
Description
Claims
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US14/697,551 US9835228B2 (en) | 2014-04-27 | 2015-04-27 | Advanced methods and designs for balancing a stranded termination assembly |
PCT/US2016/014464 WO2016175906A1 (en) | 2015-04-27 | 2016-01-22 | Advanced methods and designs for balancing a stranded termination assembly |
Publications (2)
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EP3289136A1 true EP3289136A1 (en) | 2018-03-07 |
EP3289136A4 EP3289136A4 (en) | 2019-01-30 |
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EP16786864.5A Withdrawn EP3289136A4 (en) | 2015-04-27 | 2016-01-22 | Advanced methods and designs for balancing a stranded termination assembly |
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EP (1) | EP3289136A4 (en) |
CA (1) | CA2984243A1 (en) |
WO (1) | WO2016175906A1 (en) |
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CN109083022B (en) * | 2018-09-30 | 2023-05-23 | 柳州欧维姆结构检测技术有限公司 | System and method for monitoring construction cable force uniformity of parallel steel strand stay cable |
SG11202108001TA (en) | 2019-01-24 | 2021-08-30 | Richard Campbell | Intelligent fiber rope termination, module and networking technologies |
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FR2498169B1 (en) * | 1981-01-19 | 1985-06-28 | Kley France | CABLE TIGHTENING CORNER AND HYDRAULIC LINEAR WINCH USING SUCH TIGHTENING CORNERS |
DE3138819C2 (en) * | 1981-09-30 | 1986-10-23 | Dyckerhoff & Widmann AG, 8000 München | Method for assembling a tension member running freely between its anchoring points, in particular a stay cable for a stay cable bridge |
FR2652866B1 (en) * | 1989-10-05 | 1994-01-07 | Freyssinet International | IMPROVEMENTS IN METHODS AND DEVICES FOR TURNING ON MULTI-STRANDED CABLES. |
FR2794484B1 (en) * | 1999-06-03 | 2001-08-03 | Freyssinet Int Stup | DEVICE FOR ANCHORING A STRUCTURAL CABLE |
FR2798410B1 (en) * | 1999-09-15 | 2001-11-23 | Freyssinet Int Stup | ANCHORING DEVICE FOR ATTACHING A STRUCTURAL CABLE TO A CONSTRUCTION ELEMENT |
DE10011512B4 (en) * | 2000-03-09 | 2006-04-20 | Fraunhofer-Gesellschaft zur Förderung der angewandten Forschung e.V. | Machine tool for high-precision spatial arrangement of a tool or workpiece |
JP4999236B2 (en) * | 2001-04-25 | 2012-08-15 | 勝行 戸津 | Torque control method for electric rotary tools |
US7059362B2 (en) * | 2003-10-16 | 2006-06-13 | Daniels Manufacturing Corporation | Adaptable hand operated safety cable tool |
DE102008032881B3 (en) * | 2008-07-14 | 2009-11-12 | Dywidag-Systems International Gmbh | Apparatus and method for controlling a tensioning press when tensioning a tendon |
US9103131B2 (en) * | 2009-12-24 | 2015-08-11 | Vsl International Ag | Method and system for equally tensioning multiple strands |
US10543573B2 (en) * | 2010-09-24 | 2020-01-28 | Bright Technologies, Llc | Method of terminating a stranded synthetic filament cable |
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2016
- 2016-01-22 WO PCT/US2016/014464 patent/WO2016175906A1/en active Application Filing
- 2016-01-22 CA CA2984243A patent/CA2984243A1/en not_active Abandoned
- 2016-01-22 EP EP16786864.5A patent/EP3289136A4/en not_active Withdrawn
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EP3289136A4 (en) | 2019-01-30 |
CA2984243A1 (en) | 2016-11-03 |
WO2016175906A1 (en) | 2016-11-03 |
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