US20040101681A1

US20040101681A1 - Filler potting cable termination system and process

Info

Publication number: US20040101681A1
Application number: US10/703,948
Authority: US
Inventors: Richard Campbell
Original assignee: Individual
Current assignee: Bright Technologies LLC
Priority date: 2002-11-21
Filing date: 2003-11-07
Publication date: 2004-05-27

Abstract

A new type of process for creating a termination on cables and ropes, as well as a product made by this process. The process can create a termination having a heterogenous composition. It has been found that the addition of certain solids to conventional liquid potting compounds can enhance the performance of terminations made using these compounds. In order to create a desired dispersion of the solids within the potted termination, a new potting process is employed, whereby the strands are wetted with liquid potting compound (containing the solids) before the anchor is placed over them. The anchor is then moved into place in a controlled motion. The geometry of the internal passage through the anchor (which contains the wetted strands) is shaped to take advantage of this controlled motion. The geometry causes the liquid potting compound to flow at one rate while the solids suspended therein flow at a different rate, resulting in a potted termination with a heterogeneous composition.

Description

CROSS-REFERENCES TO RELATED APPLICATIONS

Pursuant to the provisions of 37 CFR §1.53(c), this application claims the benefit of an earlier-filed provisional application. The provisional application was assigned Ser. No. 60/428,109. It was filed on Nov. 21, 2002.[0001]

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

MICROFICHE APPENDIX

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to the field of ropes and cables. More specifically, the invention comprises a system for producing a potted cable termination having varying mechanical properties over the length of the termination.

2. Description of the Related Art

Devices for mounting an anchor on the end of a wire, rope, or cable are disclosed in detail in copending U.S. application Ser. No. 60/404,973 to Campbell, which document is incorporated herein by reference. Generally, the strands proximate the end of a cable are wetted with a potting compound to affix them to an anchor. The term “potting” refers to applying a liquid “potting compound” to the cables strands in order to lock them to something else. The potting compound turns from a liquid to a solid after it has been applied.

The term “anchor” refers to the mechanical device which is affixed to the cable. The term “termination” refers to the anchor along with the attachment means and the portion of the cable subject to the attachment means. If, as an example, a short length of cable is glued inside an interior passage through an anchor, then the term “termination” would refer to the anchor, the short length of cable, and the solidified adhesive.

The most common method for potting an anchor having an internal passage is to slip the anchor down the cable, splay the strands on the end of the cable, then pull the anchor over the splayed strands so that they lie tightly within the anchor's internal passage (a sort of mold). The potting compound—in liquid form—is then poured into the open end of the fitting. It then flows in and around the strands, wetting them and locking them to the anchor.

Another method is to place the anchor on the cable and slide it a short distance down the cable's length The strands on the end of the cable are then “painted” with the liquid potting compound. The anchor is then pulled around the wetted strands, roughly molding them into the shape of the internal passage through the fitting.

BRIEF SUMMARY OF THE PRESENT INVENTION

The present invention comprises a new type of process for creating a termination on cables and ropes, as well as a product made by this process. The process can create a termination having a heterogenous composition. It has been found that the addition of certain solids to conventional liquid potting compounds can enhance the performance of terminations made using these compounds. In order to create a desired dispersion of the solids within the potted termination, a new potting process is employed, whereby the strands are wetted with liquid potting compound (containing the solids) before the anchor is placed over them. The anchor is then moved into place in a controlled motion. The geometry of the internal passage through the anchor (which contains the wetted strands) is shaped to take advantage of this controlled motion. The geometry causes the liquid potting compound to flow at one rate while the solids suspended therein flow at a different rate, resulting in a potted termination with a heterogeneous composition.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 is an isometric section view, showing a cable termination created using the novel potting compounds and process. [0012]
FIG. 2 is an isometric view, showing the first step in the process. [0013]
FIG. 3 is an isometric view, showing the second step in the process. [0014]
FIG. 3B is an isometric view, showing the potting compound being sprayed onto the exposed strands. [0015]
FIG. 4 is a section view, showing the anchor being moved into position. [0016]
FIG. 5 is a section view, showing the anchor being moved into position. [0017]
FIG. 6 is an isometric view, showing the exposed strands being dipped into a vat of potting compound. [0018]
FIG. 7 is an isometric view, showing the application of potting compound using a mold.[0019]

REFERENCE NUMERALS IN THE DRAWINGS

[0020] 10 cable 12 anchor
[0021] 14 unwetted strands 16 potting compound
[0022] 18 expanding passage 20 dense filler region
[0023] 22 sparse filler region 24 jacket
[0024] 26 exposed strands 28 mold
[0025] 30 injection port 32 spray nozzle

DESCRIPTION OF THE INVENTION

Potting compounds have been used to create potted terminations in metallic and non-metallic cables for many years. Typically these are polyester blends, some form of epoxy, thermoplastics, or molten metal. A wide variety of mechanical properties are available using such potting compounds. They are invariably added to the termination while in liquid form. They then harden in situ. [0026]
The present invention contemplates the addition of solid particles to the liquid potting compound. The use of these solids can add strength and toughness to a potted termination. It can also enhance fatigue resistance with respect to cyclic tensile and flexural loads. [0027]
There are advantages to varying the properties of the solidified potting compound over the length of a termination. A termination on the end of a cable has a first end next to the freely-flexing portion of the cable itself, and a second end opposite this first end. It may be desirable to increase the elasticity of the potting compound near the first end, yet maintain a very stiff and rigid composition near the second end. The present invention can create such a variance. [0028]
The selection of the particular solid material can significantly change the mechanical properties of the termination as a whole. As a first example, where one set of mechanical properties is desired, a soft material such as solid rubber particles can be added. As a second example, where a second set of mechanical properties is desired a hard material such as ceramic can be added. Other materials, such as aluminum, can provide a mix of mechanical properties. The list of such materials is voluminous, and would include plastics, rubber, glass, carbon, ceramics, aluminum, and ferromagnetic materials. [0029]
The addition of the solid particles can cause problems with the traditional methods of forming a potted termination. As discussed previously, a termination is typically made by pulling an anchor over exposed and unwetted strands (whether metal strands or strands made of other materials). The liquid potting compound is then poured into the open end of the anchor. The liquid potting compound must have a viscosity that is low enough to allow it to flow down through the unwetted strands and completely wet the length of strands lying within the anchor. A potting liquid containing solid particles may not behave in the same fashion. [0030]
FIG. 1 shows a desired result in the creation of a termination using suspended solid particles in the potting compound. [0031] Anchor 12 has expanding passage 18 through its middle, having a smaller diameter proximate the freely flexing portion of the cable and a large diameter proximate the opposite end. The profile of this passage can assume many shapes. For this example, a simple linear taper is used.
[0032] Potting compound 16 fills expanding passage 18 and bonds the cable strands to anchor 12 (Those skilled in the art will know that the compound may not actually adhere to the walls of expanding passage 18. In some cases, the tapered shape simply mechanically locks the solidified potting compound and strands within the passage to the anchor whenever the cable is placed in tension). Below anchor 12, unwetted strands 14 within cable 10 are free to flex according to their own mechanical properties and the construction of the cable itself. A jacket 24 may or may not be included in cable 10.
The transition from the relatively freely flexing region of [0033] unwetted strands 14 to the rigidly locked strands within anchor 12 is critical to the ultimate strength, toughness, fatigue resistance, and other properties of the termination. FIG. 1 shows the desired concentration of filler particles as dense filler region 20. The reader will observe that the concentration of particles gradually diminishes toward the open end of anchor 12. The upper region is denoted as sparse filler region 22.
A new manufacturing method is needed to produce the result shown in FIG. 1. FIG. 2 shows the first step in this new approach. [0034] Anchor 12 has been installed on cable 10 while exposed strands 26 are still in the unwetted state (Note that jacket 24 may or may not be present, depending on the type of cable to be terminated. If a jacket is present, it will have to be stripped away over a short length to reveal exposed strands 26).
The exposed strands are typically then splayed apart to form a conical shape. When in this state, the liquid potting compound with suspended filler particles is applied to the exposed strands. This step can be accomplished through a variety of known techniques—such as “painting on” the compound, spraying on the compound, inverting the assembly and dipping the exposed strands into a vat of the compound, placing the exposed strands in a cavity mold and shooting the compound in under pressure, etc. [0035]
FIG. 3 shows the potting compound painted onto and into the splayed strands using a brush or similar implement. FIG. 3B shows the potting compound, with included solids, being sprayed onto the strands (generally after a suitable solvent has been used to dilute the compound). FIG. 6 shows the anchor and cable assembly inverted prior to dipping the exposed strands into a vat of liquid potting compound. FIG. 7 shows the use of a cavity mold. Two [0036] mold halves 28 are split and the cable and exposed strands are placed into the cavity shown. The mold halves are then clamped back together prior to shooting the liquid potting compound in through injection port 30.
However the potting compound is applied, FIG. 3 shows the result. Potting [0037] compound 16, including the suspended solid particles, has wetted the exposed strands. The dispersion of solid particles within the mixture is, at this point, approximately uniform.
[0038] Anchor 12 is then moved upward toward its desired final position. FIG. 4 shows anchor 12 being moved upward. Expanding passage 18 has surrounded the strands and potting compound 16. Potting compound 16 is squeezed upward, flowing over and through the strands.
As the anchor is moved upward, the upper portion of the wall of the expanding passage (“upper” being understood with respect to the view as shown) engage the splayed strands and slowly squeezes them together. Potting [0039] compound 16's liquid component is capable of flowing in and around the small strands comprising cable 10. The suspended particles are not so able to flow freely, however. Many of the suspended particles will lodge between the strands, especially since the wall of the expanding passage is squeezing the strands together at a position which is above most of the suspended particles. Their upward movement is therefore impeded.
The gaps between the strands—where many of the suspended particles reside—continue to shrink as [0040] anchor 12 is moved upward. The result is that the rate of upward flow of the suspended particles is slower than the rate of upward flow for the liquid. In FIG. 4, the reader will observe that this difference in the rates of flow has caused a change in the concentration of suspended particles within the mixture. The density of suspended particles tapers from the bottom of the mixture to the top of the mixture. The dispersion can be altered via changing the shape of expanded passage 18, the viscosity of the potting compound, the size, finish, or shape of the particles, and the size, pattern, and finish of the strands within the cable.
This phenomenon continues in FIG. 5, showing the state of dispersion when [0041] anchor 12 has been moved further upward. Anchor 12 eventually comes to rest at the position shown in FIG. 1. Excess potting compound 16 is extruded out the open top of anchor 12, where it may be removed before hardening. Most of the solid particles, however, remain within expanding passage 18.
Those skilled in the art will know that the order of some of the steps discussed can be varied without affecting the process. As an example, the description just presented contemplated slipping the anchor down the cable, then splaying the strands. If a cable has already been cut to length, the anchor can actually be introduced from the opposite end. In such a case, the strands could be splayed apart first, with the anchor then being slid down the cable from the opposite end. The strands could even be splayed apart and infused with resin before the anchor is ever added to the cable. [0042]
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. [0043]

Claims

Having described my invention, I claim:

1. A method for affixing an anchor to a cable using a liquid potting compound containing solid particles, so that a heterogenous dispersion of said solid particles within said potting compound results, comprising:

a. providing an anchor, including:

i. a first end;

ii. a second end;

iii. an expanding passage extending from said first end to said second end, wherein said expanding passage is larger proximate said second end than said first end;

b. placing said anchor on said cable so that said first end of said anchor faces away from said end of said cable, and said second end of said anchor faces toward said end of said cable, while being distal to said end of said cable.

c. providing a liquid potting compound containing solid particles;

d. splaying a length of strands proximate said end of said cable;

e. using said length of strands with said potting compound; and

f. moving said anchor along said cable toward said end of said cable, so that said expanding passage squeezes said splayed length of strands together, thereby forcing said liquid potting compound toward said second end of said expanding passage while trapping said solid particles within said strands.

2. A method as recited in claim 1, wherein said infusing said length of strands with said liquid potting compound is accomplished by dipping said length of strands into said liquid potting compound.

3. A method as recited in claim 1, wherein said infusing said length of strands with said liquid potting compound is accomplished by placing said length of strands into a mold and filling said mold with said liquid potting compound.

4. A method as recited in claim 1, wherein said infusing said length of strands with said liquid potting compound is accomplished by painting said liquid potting compound onto said length of strands.

5. A method as recited in claim 1, wherein said infusing said length of strands with said liquid potting compound is accomplished by spraying said liquid potting compound onto said length of strands.

6. An article of manufacture prepared by a process comprising:

a. providing an anchor, including,

i. a first end;

ii. a second end;

c. providing a liquid potting compound containing solid particles;

d. splaying a length of strands proximate said end of said cable;

e. infusing said length of strands with said potting compound; and

f. moving said anchor along said cable toward said end of said cable, so that said expanding passage squeezes said splayed length of strands together, thereby forcing said liquid potting compound toward said second end ofsaid expanding passage while trapping said solid particles within said strands.

7. An article of manufacture as recited in claim 6, wherein said step of infusing said length of strands with said liquid potting compound is accomplished by dipping said length of strands into said liquid potting compound.

8. An article of manufacture as recited in claim 6, wherein said step of infusing said length of strands with said liquid potting compound is accomplished by placing said length of strands into a mold and filling said mold with said liquid potting compound.

9. An article of manufacture as recited in claim 6, wherein said step of infusing said length of strands with said liquid potting compound is accomplished by painting said liquid potting compound onto said length of strands.

10. An article of manufacture as recited in claim 6, wherein said step of infusing said length of strands with said liquid potting compound is accomplished by spraying said liquid potting compound onto said length of strands.