HK1251351B - Electrical transmission cables with composite cores - Google Patents

Description

Power transmission cables with composite cores

This application is a divisional application of the Chinese invention patent application entitled “Power Transmission Cable with Composite Core” filed on April 11, 2012, with application number 201280022956.0. Application 201280022956.0 is a national application filed under the Patent Cooperation Treaty that entered the Chinese national phase of international application PCT/US2012/033077.

Citation of Related Applications

International application PCT/US2012/033077 was filed on April 11, 2012, as a PCT international patent application designating all countries in the name of Allan Daniel, a U.S. citizen; Paul Springer, a U.S. citizen; Yuhsin Hawig, a Taiwanese citizen; Mark Lancaster, a U.S. citizen; David W. Eastep, a U.S. citizen; Sherri M. Nelson, a U.S. citizen; Tim Tibor, a U.S. citizen; Tim Regan, a U.S. citizen; and Michael L. Wesley, a U.S. citizen, and claims priority to U.S. patent application serial No. 61/474,423, filed on April 12, 2011, and related provisional application serial No. 61/474,458, filed on April 12, 2011, both of which are incorporated herein by reference in their entireties.

Technical Field

The present application relates to a power transmission cable having a composite core and a method for making the same.

Background Art

Composite wire structures are often used as transmission lines or cables for delivering electricity to users. Examples of composite transmission line structures include, for example, aluminum conductor steel reinforced (ACSR) cable, aluminum conductor steel supported (ACSS) cable, aluminum conductor composite reinforced (ACCR) cable, and aluminum conductor composite core (ACCC) cable. ACSR and ACSS cables include an outer conductive layer of aluminum surrounding an inner steel core. Transmission lines or cables are designed to not only transmit electricity efficiently, but also to be robust and temperature-resistant, especially when the transmission lines are tied to towers and run over long distances.

It would be beneficial to produce cables having composite cores that achieve the desired strength, durability, and temperature characteristics required for applications such as overhead power transmission cables.

Summary of the Invention

This summary is provided to introduce selected concepts in a simplified form that will be further described in the detailed description below. This summary is not intended to identify necessary or essential features of the claimed subject matter. This summary is also not intended to limit the scope of the claimed subject matter.

Embodiments of the present invention can provide cables, such as power transmission cables for overhead power transmission, which can include a cable core and conductive elements surrounding the cable core. The cable core can include at least one composite core (also known as a composite strand or polymer composite strand). These core elements can serve as load-bearing components of the power transmission cable, and in some embodiments, these core elements can be non-conductive.

According to one embodiment of the present invention, a composite core of a cable is disclosed. Generally, the cables and cores disclosed herein can extend longitudinally. The composite core can include at least one rod, the rod comprising a plurality of consolidated thermoplastic impregnated rovings containing a continuous fiber component (the rod is also referred to as a fiber core). The roving can include longitudinally oriented continuous fibers and a thermoplastic matrix embedded with the fibers. The ratio of the ultimate tensile strength of the fibers to the mass per unit length is greater than about 1,000 megapascals per gram per meter (MPa/g/m). The continuous fibers can constitute about 25% to about 80% by weight of the rod, and the thermoplastic matrix can constitute about 20% to about 75% by weight of the rod. A capping layer can surround the rod, and the capping layer may not contain continuous fibers. The composite core can have a minimum flexural modulus of about 10 gigapascals (GPa).

According to another embodiment of the present invention, a method for forming a composite core for a power transmission cable is disclosed. The method comprises: impregnating a plurality of rovings with a thermoplastic matrix and merging the rovings to form a ribbon, wherein the rovings may comprise longitudinally oriented continuous fibers. The ratio of the ultimate tensile strength of the fibers to the mass per unit length may be greater than about 1,000 MPa/g/m. The continuous fibers may constitute about 25% to about 80% by weight of the ribbon, and the thermoplastic matrix may constitute about 20% to about 75% by weight of the ribbon. The ribbon may be heated to a temperature equal to or greater than the softening temperature (or melting temperature) of the thermoplastic matrix and drawn through at least one forming die to compress and shape the ribbon into a strip. A cover layer may be applied to the strip to form a composite core.

According to another embodiment of the present invention, a method for preparing a cable is disclosed. The method may include providing a cable core comprising at least one composite core, and surrounding the cable core with a plurality of conductive elements. The composite core may include at least one strip comprising a plurality of combined thermoplastic-impregnated rovings. The rovings may include longitudinally oriented continuous fibers and a thermoplastic matrix in which the fibers are embedded. The ratio of the ultimate tensile strength of the fibers to the mass per unit length may be greater than about 1,000 MPa/g/m. Typically, the strip may comprise from about 25% to about 80% by weight of fibers, and from about 20% to about 75% by weight of the thermoplastic matrix. A covering layer may surround the at least one strip, which covering layer generally may not contain continuous fibers. In these and other embodiments, the composite core may have a flexural modulus greater than about 10 GPa.

Both the foregoing brief description and the detailed description below provide examples and are intended to be illustrative only. Therefore, the foregoing brief description and the detailed description below should not be considered restrictive. In addition, features or variations other than those provided herein may be provided. For example, certain aspects and embodiments may involve combinations and sub-combinations of the multiple features described in the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute a part of this disclosure, illustrate several aspects of embodiments of the present invention. In the drawings:

FIG1 is a perspective view of one embodiment of a consolidated strip used in the present invention;

FIG2 is a cross-sectional view of another embodiment of a merged strip used in the present invention;

FIG3 is a schematic diagram of one embodiment of an impregnation system used in the present invention;

FIG4 is a cross-sectional view of the impregnation die shown in FIG3 ;

FIG5 is an exploded view of one embodiment of a manifold assembly and gate passage of an impregnation die that may be used in the present invention;

FIG6 is a perspective view of one embodiment of a plate at least partially defining an impregnation zone that may be used in the present invention;

FIG7 is a schematic diagram of one embodiment of a pultrusion system that may be used in the present invention;

FIG8 is a perspective view of one embodiment of a composite core of the present invention; and

FIG9 is a perspective view of an embodiment of a power transmission cable of the present invention;

FIG10 is a perspective view of another embodiment of a power transmission cable of the present invention;

FIG11 is a top cross-sectional view of one embodiment of a plurality of calibration dies that may be used in accordance with the present invention;

FIG12 is a side cross-sectional view of one embodiment of a calibration die that may be used in accordance with the present invention;

FIG13 is a front view of a portion of one embodiment of a calibration die that may be used in accordance with the present invention;

FIG14 is a front view of one embodiment of a forming roller that may be used in accordance with the present invention;

FIG15 is a perspective view of a cable according to Embodiments 6 to 7;

FIG16 is a stress-strain diagram of the cable of Example 7; and

FIG17 is a perspective view of a cable according to constructive embodiment 8;

DETAILED DESCRIPTION

The following detailed description refers to the accompanying drawings. Wherever possible, the same or similar reference numerals used in the drawings and the following description refer to the same or similar elements or features. Although aspects and embodiments of the present invention may be described, modifications, adaptive changes and other implementations are also possible. For example, the elements described in the drawings may be replaced, added or modified, and the methods described herein may be changed by replacing, rearranging or adding the steps of the disclosed methods. Therefore, the following detailed description and its exemplary embodiments do not limit the scope of the present invention.

The present invention generally relates to cables, such as high voltage overhead transmission lines, and also to composite cores contained in these cables. In certain embodiments of the present invention, the cable may comprise a cable core comprising at least one composite core (or composite strand) and a plurality of conductive elements surrounding the cable core.

Composite core

The composite core may comprise a strip (or fiber core) comprising a continuous fiber component surrounded by a cover layer. The strip may comprise a plurality of unidirectionally aligned fiber rovings embedded in a thermoplastic polymer matrix. Although not wishing to be bound by theory, the applicant believes that the degree of impregnation of the rovings with the thermoplastic polymer matrix can be significantly improved by selectively controlling the impregnation process, and also by controlling the degree of compression applied to the rovings during the formation and shaping of the strip, and calibrating the geometry of the final strip. Such a well-impregnated strip can have a very low porosity, which can produce excellent strength properties. Obviously, the desired strength properties can be achieved without the need for different fiber types within the strip.

As used herein, the term "roving" generally refers to a bundle or tow of individual fibers. The fibers contained in a roving can be twisted or straight. Although different fibers can be used in individual or different rovings, it is advantageous for each roving to contain a single fiber type so that the negative impact of using materials with different thermal expansion coefficients is minimized. The continuous fibers used in the rovings can have a high degree of tensile strength relative to their mass. For example, the ultimate tensile strength of the fibers can generally be from about 1,000 to about 15,000 megapascals (MPa), in some embodiments from about 2,000 MPa to about 10,000 MPa, and in some embodiments from about 3,000 MPa to about 6,000 MPa. Such tensile strength can be achieved even if the fibers have a relatively light weight (e.g., a mass per unit length of from about 0.1 to about 2 grams per meter (g/m), in some embodiments from about 0.4 to about 1.5 g/m). Thus, the ratio of tensile strength to mass per unit length may be 1,000 megapascals per gram per meter (MPa/g/m) or greater, in some embodiments about 4,000 MPa/g/m or greater, and in some embodiments, from about 5,500 to about 20,000 MPa/g/m. Such high-strength fibers can be, for example, metal fibers, glass fibers (e.g., E-glass, A-glass, C-glass, D-glass, AR-glass, R-glass, Si-glass, S2-glass, etc.), carbon fibers (e.g., amorphous carbon, graphite carbon, or metal-coated carbon, etc.), boron fibers, ceramic fibers (e.g., alumina or silica), aramid fibers (e.g., sold by E.I. duPont de Nemours, Wilmington, Del.), synthetic organic fibers (e.g., polyamide, polyethylene, paraphenylene, terephthalamide, polyethylene terephthalate, and polyphenylene sulfide), and various other natural or synthetic inorganic or organic fiber materials known for reinforcing thermoplastic and/or thermosetting compositions. Carbon fibers are particularly suitable for use as continuous fibers, and their ratio of tensile strength to mass per unit length is typically from about 5,000 to about 7,000 MPa/g/m. Typically, the continuous fibers may have a nominal diameter of about 4 to about 35 micrometers (μm), and in some embodiments, about 5 to about 35 μm. The number of fibers contained in each roving may be constant or may vary from roving to roving. Typically, a roving may contain from about 1,000 to about 100,000 individual fibers, and in some embodiments, from about 5,000 to about 50,000 individual fibers.

Any of a variety of thermoplastic polymers can be used to form the thermoplastic matrix in which the continuous fibers are embedded. Suitable thermoplastic polymers for use in the present invention may include, for example, polyolefins (e.g., polypropylene, propylene-ethylene copolymers, etc.), polyesters (e.g., polybutylene terephthalate (PBT)), polycarbonates, polyamides (e.g., Nylon ^™ ), polyetherketones (e.g., polyetheretherketone (PEEK)), polyetherimides, polyarylketones (e.g., polyphenylenedione (PPDK)), liquid crystal polymers, polyaryl sulfides (e.g., polyphenylene sulfide (PPS), poly(diphenylene sulfide ketone), poly(phenylene sulfide diketone), poly(diphenylene sulfide)), fluoropolymers (e.g., polytetrafluoroethylene-perfluoromethyl vinyl ether polymers, perfluoro-alkoxyalkane polymers, tetrafluoroethylene polymers, ethylene-tetrafluoroethylene polymers, etc.), polyacetals, polyurethanes, polycarbonates, styrenic polymers (e.g., acrylonitrile butadiene styrene (ABS), etc.), or combinations thereof.

Generally speaking, the properties of the thermoplastic matrix can be selected to achieve a desired combination of processability and end-use properties for the composite core. For example, the melt viscosity of the thermoplastic matrix can generally be low enough to allow the polymer to adequately impregnate the fibers and form into a strip-like configuration. In this regard, the melt viscosity, determined at operating conditions for thermoplastic polymers (e.g., approximately 360°C), is typically from about 25 to about 2,000 Pascal-seconds (Pa-s), in some embodiments, from 50 to about 500 Pa-s, and in some embodiments, from about 60 to about 200 Pa-s. Similarly, because the core may be used at high temperatures (e.g., in high-voltage transmission cables), thermoplastic polymers with relatively high melting temperatures can be used. For example, the melting temperature of such high-temperature polymers can be from about 200°C to about 500°C, in some embodiments, from about 225°C to about 400°C, and in some embodiments, from about 250°C to about 350°C.

In certain embodiments contemplated herein, polyarylene sulfide can be used as a high temperature matrix having a desirable melt viscosity in the present invention. For example, polyphenylene sulfide is a semicrystalline resin that generally comprises repeating monomer units represented by the following general formula:

These monomer units may constitute at least 80 mol%, in some cases at least 90 mol%, of the repeating units in the polymer. However, it will be understood that the polyphenylene sulfide may contain additional repeating units, such as those described in U.S. Pat. No. 5,075,381 to Gotoh et al., which is incorporated herein by reference in its entirety for all purposes. When used, the additional units may generally constitute less than about 20 mol% of the polymer. Commercially available high melt viscosity polyphenylene sulfides may include those available from Ticona, LLC (Florence, Kentucky) under the trade name POLYMERIZER®. Such polymers may have a melt temperature of about 285° C. (determined according to ISO 11357-1, 2, 3) and a melt viscosity of about 260 to about 320 Pa-s at 310° C.

According to the present invention, an extrusion device can generally be used to impregnate rovings with a thermoplastic matrix. Among other things, the extrusion device can help apply the thermoplastic polymer to the entire surface of the fiber. The impregnated rovings also have a very low porosity, which can increase the strength of the resulting strip material. For example, the porosity can be about 6% or less, in some embodiments about 4% or less, in some embodiments about 3% or less, in some embodiments about 2% or less, in some embodiments about 1% or less, and in some embodiments about 0.5% or less. Porosity can be measured using techniques well known to those skilled in the art. For example, it can be measured using a "resin burnout" test, in which a sample is placed in an oven (e.g., at 600°C for 3 hours) to burn out the resin. The mass of the remaining fiber can then be measured to calculate the weight fraction and volume fraction. This "burnout" test can be performed according to ASTM D2584-08 to determine the weight of the fiber and the thermoplastic matrix, and the "porosity" can then be calculated based on the following formula:

V _f = 100*(ρ _t -ρ _c )/ρ _t

in,

_Vf is the porosity in percentage;

_ρc is the density of the composite material measured using known techniques, such as measurement using a liquid pycnometer or a gas pycnometer (e.g., a helium pycnometer).

_ρt is the theoretical density of the composite material determined using the following formula:

ρ _t =1/[W _f /ρ _f +W _m /ρ _m ]

_ρm is the density of the thermoplastic matrix (e.g., at an appropriate degree of crystallinity);

ρ _f is the density of the fiber;

_Wf is the weight fraction of fiber; and

_Wm is the weight fraction of the thermoplastic matrix.

Alternatively, porosity can be determined by chemically dissolving the resin according to ASTM D 3171-09. The "burnout" and "dissolution" methods described above may be particularly suitable for glass fibers, which are generally resistant to melting and chemical dissolution. However, in other cases, porosity can be calculated indirectly based on the density of thermoplastic polymers, fibers, and ribbons (or tapes) according to ASTM D 2734-09 (Method A), where the density can be determined by ASTM D 792-08 Method A. Of course, porosity can also be estimated using conventional microscopy equipment or by using computed tomography (CT) scanning equipment (e.g., Metrotom 1500 (2k×2k) high-resolution detector).

Referring to FIG3 , an embodiment of an extrusion apparatus is shown. More specifically, the apparatus may include an extruder 120 comprising a screw shaft 124 mounted within a barrel 122. A heater 130 (e.g., a resistance heater) may be mounted on the exterior of the barrel 122. In use, a thermoplastic polymer feedstock 127 may be supplied to the extruder 120 via a hopper 126. The thermoplastic feedstock 127 may be conveyed into the interior of the barrel 122 via the screw shaft 124 and heated by friction within the barrel 122 and the heater 130. After heating, the feedstock 127 may exit the barrel 122 via a barrel flange 128 and enter a die flange 132 of an impregnation die 150.

A continuous fiber roving 142 or a plurality of continuous fiber rovings 142 can be supplied to a die 150 from one or more reels 144. Typically, the rovings 142 can be spaced a certain distance prior to impregnation, for example, at least about 4 mm apart, and in some embodiments, at least about 5 mm apart. The feedstock 127 can be further heated by a heater 133 mounted within or around the die 150. The die can generally be operated at a temperature sufficient to melt and impregnate the thermoplastic polymer. Typically, the operating temperature of the die can be above the melting temperature of the thermoplastic polymer, for example, at a temperature of about 200° C. to about 450° C. When processed in this manner, the continuous fiber rovings 142 can be embedded in a polymer matrix, which can be a resin 214 ( FIG. 4 ) processed from the feedstock 127. The mixture can be extruded from the impregnation die 150 to produce an extrudate 152.

The pressure near the impregnation die 150 can be monitored using a pressure sensor 137 ( FIG. 3 ), allowing the extruder 120 to be operated to deliver the appropriate amount of resin 214 to interact with the fiber rovings 142. The extrusion rate can be varied by controlling the rotational speed of the screw shaft 124 and/or the feed rate of the feedstock 127. The extruder 120 can be operated to produce an extrudate 152 (impregnated fiber roving), which, after exiting the impregnation die 150, can enter an optional pre-forming or guiding section (not shown) and then a nip formed between two adjacent rollers 190. The rollers 190 can help consolidate the extrudate 152 into a strip (or ribbon) form, improve fiber impregnation, and squeeze out any excess voids. In addition to the rollers 190, other forming devices, such as a die system, can also be used. The resulting consolidated strip 156 can be drawn out via tracks 162 and 164 mounted on the rollers. Track belts 162 and 164 may also pull extrudate 152 from impregnation die 150 and through rollers 190. If desired, combined rovings 156 may be wound onto portion 171. Generally, the tapes may be relatively thin and may have a thickness of about 0.05 to about 1 millimeter (mm), in some embodiments, about 0.1 to about 0.8 mm, and in some embodiments, about 0.2 to about 0.4 mm.

In the impregnation die, it may be advantageous to pass the rovings 142 through an impregnation zone 250 to impregnate the rovings with the polymer resin 214. In the impregnation zone 250, the polymer resin can generally be forced through the rovings by shear forces and pressure generated within the impregnation zone 250, which can significantly increase the degree of impregnation. This can be particularly useful when forming composite materials from strips with high fiber content (e.g., about 35% by weight (Wf) or more, and in some embodiments, about 40% Wf or more). Typically, the die 150 can include a plurality of contact surfaces 252, e.g., at least 2, at least 3, 4 to 7, 2 to 20, 2 to 30, 2 to 40, 2 to 50, or more, to create sufficient penetration and pressure on the rovings 142. While their specific form can vary, the contact surfaces 252 can typically have curved surfaces, such as curved lobes, rods, etc. The contact surfaces 252 can typically be made of a metallic material.

FIG4 shows a cross-sectional view of the impregnation die 150. As shown, the impregnation die 150 may include a manifold 220, a gate channel 270, and an impregnation zone 250. The manifold 220 may be configured to allow the polymer resin 214 to flow therethrough. For example, the manifold 220 may include one channel 222 or a plurality of channels 222. The resin 214 provided to the impregnation die 150 may flow through the channels 222.

As shown in FIG5 , some portions of the channel 222 may be curved, and in an exemplary embodiment, the channel 222 may have a symmetrical orientation along the central axis 224. Additionally, in some embodiments, the channel may be a plurality of branched runners 222, which may include a first branched runner group 232, a second group 234, a third group 236, and, if desired, further branched runner groups. Each group may include two, three, four, or more runners 222 branching from a runner 222 in a previous group or from the initial channel 222.

The branching flow channels 222 and their symmetrical orientation can evenly distribute the resin 214 so that the flow of resin 214 exiting the manifold 220 and coating the rovings 142 can be substantially evenly distributed across the rovings 142. Advantageously, this can result in a generally uniform impregnation of the rovings 142.

Additionally, in some embodiments, the manifold 220 can define an outlet region 242 that generally encompasses at least the downstream portion of the channels or runners 222 from which the resin 214 exits. In some embodiments, at least the portion of the channels or runners 222 disposed within the outlet region 242 has an increased area in the flow direction 255 of the resin 214. The increased area can allow for diffusion and further distribution of the resin 214 as it flows through the manifold 220, which can further result in a substantially uniform distribution of the resin 214 across the rovings 142.

4 and 5 , after flowing through the manifold 220, the resin 214 may flow through a gate channel 270. The gate channel 270 may be disposed between the manifold 220 and the impregnation zone 250 and may be configured for the flow of the resin 214 from the manifold 220 such that the resin 214 coats the rovings 142. Thus, as shown, the resin 214 exiting the manifold 220 through, for example, the outlet zone 242 may enter the gate channel 270 and flow therethrough.

4 , after exiting the manifold 220 and gate channel 270 of the die 150, the resin 214 may contact the rovings 142 passing through the die 150. As discussed above, due to the distribution of the resin 214 within the manifold 220 and gate channel 270, the resin 214 may substantially uniformly coat the rovings 142. Additionally, in some embodiments, the resin 214 may impinge upon the upper surface of each roving 142, upon the lower surface of each roving 142, or upon both the upper and lower surfaces of each roving 142. The initial impingement of the rovings 142 may provide for further impregnation of the rovings 142 with the resin 214.

4 , the coated rovings 142 may be passed in a direction of motion 282 through an impregnation zone 250 configured to impregnate the rovings 142 with the resin 214. For example, as shown in FIGS. 4 and 6 , the rovings 142 may be moved over a contact surface 252 within the impregnation zone. The impact of the rovings 142 on the contact surface 252 may generate shear forces and pressure sufficient to cause the resin 214 to impregnate the rovings 142, thereby coating the rovings 142.

In some embodiments, as shown in FIG4 , the impregnation zone 250 may be defined between two spaced-apart, opposing plates 256 and 258. The first plate 256 may define a first inner surface 257, while the second plate 258 may define a second inner surface 259. The contact surface 252 may be defined on or as an extension of both the first inner surface 257 and the second inner surface 259, or only one of the first inner surface 257 and the second inner surface 259. According to these embodiments, FIG6 illustrates the second plate 258 and the plurality of contact surfaces thereon, which may form at least a portion of the impregnation zone 250. In an exemplary embodiment, as shown in FIG4 , the contact surfaces 252 may be alternately defined on the first surface 257 and the second surface 259, such that the rovings 142 impact the contact surfaces 252 alternately on the first surface 257 and the second surface 259. As a result, the rovings 142 may pass through the contact surfaces 252 in a wavy, curved, or sinusoidal path, which increases shear forces.

The angle 254 at which the rovings 142 pass through the contact surface 252 can generally be large enough to increase shear forces, but not so large as to cause excessive forces to break the fibers. Thus, for example, the angle 254 can be from about 1° to about 30°, and in some embodiments, from about 5° to about 25°.

In some alternative embodiments, the impregnation zone 250 may include a plurality of needles (not shown). Each needle may have a contact surface 252. The needles may be stationary, freely rotating, or rotationally driven. In other alternative embodiments, the contact surface 252 and the impregnation zone 250 may be of any suitable shape and/or configuration to impregnate the rovings 142 with the resin 214 as desired or needed.

To further aid in impregnation of the rovings 142, the rovings 142 may be held under tension while in the impregnation die. The tension applied to each roving 142 or each fiber bundle may be, for example, from about 5 to about 300 Newtons (N), in some embodiments, from about 50 to about 250 N, and in some embodiments, from about 100 to about 200 N.

As shown in FIG4 , in some embodiments, a land zone 280 can be positioned downstream of the impregnation zone 250 in the direction 282 of travel of the rovings 142. The rovings 142 can move through the land zone 280 before exiting the die 150. As further shown in FIG4 , in some embodiments, a faceplate 290 can be adjacent to the impregnation zone 250. The faceplate 290 can generally be configured to meter excess resin 214 from the rovings 142. Thus, the holes in the faceplate 290 through which the rovings 142 pass can be sized to remove excess resin 214 from the rovings 142 as the rovings 142 pass through the holes.

The impregnation die shown and described above is only one of many possible configurations that can be used in the present invention. For example, in an alternative embodiment, the roving can be introduced into a crosshead die arranged at a certain angle relative to the flow direction of the polymer melt. As the roving moves through the crosshead die and reaches the point where the polymer exits the extruder barrel, the polymer can be forced into contact with the roving. Examples of such crosshead die extruders are described, for example, in U.S. Patents: Moyer No. 3,993,726, Chung et al. No. 4,588,538, Augustin et al. No. 5,277,566, and Amaike et al. No. 5,658,513, which are incorporated herein by reference in their entirety for all purposes. It should be understood that any other extruder design, such as a twin-screw extruder, may also be used. Furthermore, other optional components may be used to assist in the impregnation of the fiber. For example, in certain embodiments, a "gas nozzle" assembly can be used to help evenly spread individual fiber rovings, each of which can contain up to 24,000 fibers, across the width of the fused bundle. This can help achieve evenly distributed strength properties. Such an assembly can include a device that provides compressed air or other gas that impinges in a generally vertical manner on the moving roving as it passes through an outlet. The spread roving can then be introduced into a die for impregnation, as described above.

Regardless of the technology used, the continuous fibers can be oriented longitudinally (machine direction "A" of the system of Figure 3) to increase their tensile strength. In addition to the fiber direction, other aspects of the pultrusion process can also be controlled to obtain the desired strength. For example, a relatively high percentage of continuous fibers can be used in the combined strips to provide enhanced strength properties. For example, the continuous fibers can typically constitute about 25% to about 80% by weight of the strips, in some embodiments, about 30% to about 75% by weight, and in some embodiments, about 35% to about 60% by weight. Similarly, thermoplastic polymers can typically constitute about 20% to about 75% by weight of the strips, in some embodiments, about 25% to about 70% by weight, and in some embodiments, about 40% to about 65% by weight. The percentages of fibers and thermoplastic matrix in the final strips can also be within the above ranges.

As described above, rovings can be combined into one or more strip forms and then formed into the desired strip configuration. When such strips are subsequently compressed, the rovings can be distributed around the longitudinal center of the strip in a roughly uniform manner. Such uniform distribution improves the consistency of strength properties (e.g., flexural modulus, ultimate tensile strength, etc.) over the entire length of the strip. When in use, the number of combined strips used to form the strip can vary depending on the desired strip thickness and/or cross-sectional area and strength, as well as the properties of the strip itself. However, in most cases, the number of strips can be 1 to 20, and in some embodiments, 2 to 10. Similarly, the number of rovings used in each strip can be different. However, typically the strip can contain 2 to 10 rovings, and in some embodiments, 3 to 5 rovings. In order to obtain a uniform distribution of rovings in the final strip, it may be advantageous to space the rovings apart from each other at roughly the same distance within the strip. For example, referring to FIG1 , one embodiment of a combined strip 4 is shown that includes three rovings 5 spaced equidistant from one another in the −x direction. However, in other embodiments, it may be desirable to combine the rovings so that the fibers of the rovings are substantially evenly distributed throughout the strip 4. In these embodiments, the rovings may be generally indistinguishable from one another. For example, referring to FIG2 , one embodiment of a combined strip 4 is shown that includes combined rovings so that the rovings are substantially evenly distributed.

The specific manner in which the roving is formed can also be carefully controlled to ensure that a strip having sufficient compression and strength properties can be formed. For example, referring to Figure 7, a specific embodiment of a system and method for forming a strip is shown. In this embodiment, two strips 12 can initially be provided in a winding assembly (package) on a creel 20. The creel 20 can be a take-up creel, which includes a frame provided with a transverse mandrel 22, each frame supporting the assembly. A pay-off creel can also be used, particularly if it is necessary to twist the fiber, such as when using coarse fiber in a one-step configuration. It should also be understood that the strip can also be formed coaxially with the formation of the strip. For example, in one embodiment, the extrudate 152 leaving the impregnation die 150 of Figure 3 can be provided directly to the system for forming the strip. A tension adjustment device 40 can also be used to help control the degree of tension in the strip 12. The device 40 can include an inlet plate 30, which is located in a vertical plane parallel to the main axis of rotation 22 of the creel 20 and/or perpendicular to the incoming strip. The tension adjustment device 40 may include cylindrical rods 41 arranged in a staggered arrangement so that the strip 12 can pass over and under these rods to define an undulating pattern. The height of the rods can be adjusted to change the amplitude of the undulating pattern and control the tension.

Before entering the merging die 50, the strips 12 can be heated in an oven 45. Any known type of oven can be used for heating, such as an infrared oven, a convection oven, and the like. During the heating process, the fibers in the strips can be oriented unidirectionally to maximize exposure to heat and maintain uniform heating throughout the strips. The temperature to which the strips are heated is generally high enough to soften the thermoplastic polymer to the extent that the strips can be bonded together. However, the temperature may not be higher than that which destroys the integrity of the material. For example, the temperature can be from about 100°C to about 500°C, in some embodiments, from about 200°C to about 400°C, and in some embodiments, from about 250°C to about 350°C. For example, in one particular embodiment, polyphenylene sulfide ("PPS") can be used as the polymer, and the strips can be heated to a temperature equal to or higher than the melting point of PPS (which can be about 285°C).

After heating, the strips 12 can be provided to a merging die 50, which can compress the strips together into a preform 14 and can arrange and form the initial shape of the strip. For example, as generally shown in Figure 7, the strips 12 can be guided in a direction "A" from an inlet 53 to an outlet 55 through a flow channel 51 of the die 50. The channel 51 can be any of a variety of shapes and/or sizes to achieve a strip configuration. For example, the channel and strip configuration can be circular, elliptical, parabolic, trapezoidal, rectangular, etc. Within the die 50, the strips are generally maintained at a temperature equal to or above the melting point of the thermoplastic matrix used in the strip to ensure proper merging.

By using a die 50 having one or more sections, the desired heating, compression, and shaping of the strip 12 can be achieved. For example, although not shown in detail herein, the combined die 50 can have multiple sections that work together to compress and shape the strip 12 into the desired configuration. For example, the first section of the channel 51 can be a tapered region that initially shapes the material as it flows into the die. The tapered region can generally have a larger cross-sectional area at its inlet than at its outlet. For example, the cross-sectional area of the channel 51 at the inlet of the tapered region can be 2% or more, in some embodiments, 5% or more, and in some embodiments, from about 10% to about 20% greater than the cross-sectional area at the outlet of the tapered region. Regardless, within the tapered region, the cross-sectional area of the flow channel can generally change gradually and smoothly to maintain a balanced flow of the composite material through the die. The tapered region can be followed by a shaping region that compresses the material and provides a generally uniform flow therethrough. The forming zone can also preform the material into a shape similar to the strip, but typically with a larger cross-sectional area to allow for transitional shapes as the thermoplastic polymer expands upon heating, minimizing the risk of blockage within the die 50. The forming zone can also include one or more surface features that directionally modify the preform. This directionality can redistribute the material, resulting in a more even distribution of fibers/resin in the final shape. This can also reduce the risk of dead spots in the die that could cause resin burns. For example, in the forming zone, the cross-sectional area of the channel 51 can be 2% or more, in some embodiments 5% or more, and in some embodiments, approximately 10% to about 20% greater than the width of the preform 14. The die flat zone can serve as the outlet for the channel 51 after the forming zone. The forming zone, tapered zone, and/or die flat zone can be heated to a temperature equal to or greater than the glass transition temperature or melting point of the thermoplastic matrix.

If desired, a second die 60 (e.g., a calibration die) may also be used to compress the preform 14 into the final shape of the strip. When in use, it may be advantageous to allow the preform 14 to cool briefly after leaving the merging die 50 and before entering the optional second die 60. This allows the initial shape of the merged preform 14 to be maintained before further advancement through the system. Typically, cooling reduces the external temperature of the strip to below the melting point of the thermoplastic matrix to minimize and substantially prevent melt fracture on the outer surface of the strip. However, the internal cross-section of the strip may remain molten to ensure compression as the strip enters the calibration die. Such cooling can be accomplished by simply exposing the preform 14 to ambient air (e.g., room temperature) or by using active cooling techniques known in the art (e.g., water bath or air cooling). For example, in one embodiment, air may be blown onto the preform 14 (e.g., using an air ring). However, cooling between these stages may generally be performed for a relatively short period of time to ensure that the preform 14 is still soft enough for further shaping. For example, after exiting the merging die 50, the preform may be exposed to ambient air for only about 1 to about 20 seconds, and in some embodiments, about 2 to about 10 seconds, before entering the second die 60. Within the die 60, the preform may generally be maintained at a temperature below the melting point of the thermoplastic matrix used in the strip to maintain the shape of the strip. Although reference is made above to a single die, it should be understood that in practice the dies 50 and 60 may be formed from multiple separate dies (e.g., a panel die).

Thus, in some embodiments, multiple individual dies 60 can be used to gradually shape the material into the desired configuration. The dies 60 can be arranged in series and configured to gradually reduce the overall dimensions of the material. Such gradual reduction can allow for shrinkage during and between steps.

For example, as shown in Figures 11 to 13, the first die 60 may include one or more inlets 62 and corresponding outlets 64 as shown in the figures. Any number of inlets 62 and corresponding outlets 64 may be included in the die 60, for example, 4 as shown, or 1, 2, 3, 5, 6 or more. In some embodiments, the inlet 62 may generally be an elliptical or circular shape. In other embodiments, the inlet 62 may have a curved rectangular shape, that is, a rectangular shape with curved corners or a rectangular shape with a straight longer side wall and a curved shorter side wall. In addition, the outlet 64 may generally be an elliptical or circular shape or may have a curved rectangular shape. In some embodiments using an elliptical inlet, the ratio of the major axis length 66 of the inlet 62 to the minor axis length 68 may be from about 3:1 to about 5:1. In some embodiments using an elliptical or circular inlet, the ratio of the major axis length 66 of the outlet 64 to the minor axis length 68 may be from about 1:1 to about 3:1. In embodiments using a curved rectangular shape, the ratio of the major axis length 66 to the minor axis length 68 (aspect ratio) of the inlet and outlet may be from about 2:1 to about 7:1, and the ratio of the outlet 64 may be less than that of the inlet 62 .

In other embodiments, the cross-sectional area of the inlet 62 of the first die 60 and the corresponding cross-sectional area of the outlet 64 may be in a ratio of about 1.5:1 to 6:1.

The first die head 60 can be roughly and smoothly converted into a shape of the final shape of the polymer-impregnated fiber material relatively similar to the gained strip material, and the strip material has a circular or oval cross section in an exemplary embodiment. Subsequent die heads, such as the second die head 60 and the third die head 60 shown in Figure 11, can further gradually reduce and/or change the size of the material, thereby the shape of the material is converted into the final cross-sectional shape of the strip material. These subsequent die heads 60 can shape and cool the material. For example, in some embodiments, each subsequent die head 60 can remain at a temperature lower than the previous die head. In an exemplary embodiment, all die heads 60 can remain at a temperature higher than the softening point temperature of the material.

In other exemplary embodiments, due to proper cooling and solidification (which may be important for achieving the desired rod shape and size), it may be desirable to have a die 60 with a relatively long straight section length 69. A relatively long straight section length 69 can reduce pressure and provide a smooth transition to the desired shape and size with minimal porosity and tortuosity. For example, in some embodiments, for example, the ratio of the length 69 of the straight section at the outlet 64 to the major axis length 66 at the outlet 64 can be from 0 to about 20, such as from about 2 to about 6, for the die 60.

As discussed, the cross-section of the material can be gradually changed using a calibrated die 60 according to the present disclosure. In an exemplary embodiment, these gradual changes can ensure that the resulting product (e.g., a rod or other suitable product) has a generally uniform fiber distribution and relatively minimal porosity.

It will be appreciated that any suitable number of dies 60 may be used to gradually form the material into a profile having a suitable cross-sectional shape, as desired or required for various end-use applications.

Except using one or more die heads, other machinery can also be used to help preform 14 be compressed into the shape of strip material, for example, can use forming roller 90 as shown in Figure 14 between merging die 50 and calibration die 60, between each calibration die 60 and/or after calibration die 60 to further compress it before preform 14 is converted into its final shape.Described roller can have any configuration, for example pinch roller (pinch roller), overlapping roller (overlapping roller) etc., and can be vertical roller or horizontal roller as shown in the figure.According to the configuration of roller 90, the surface of roller 90 can be processed into the size that makes preform 14 have finished product (for example, strip material, core, profile or other suitable products).In exemplary embodiment, the pressure of adjustable roller 90 is to optimize the quality of finished product.

In an exemplary embodiment, roller 90 may have a generally smooth surface, for example, at least in the portion that contacts the material. For example, in many embodiments, a relatively hard, polished surface may be advantageous. For example, the surface of the roller may be formed from relatively smooth chrome or other suitable material. This may allow roller 90 to manipulate the preform without damaging or undesirably altering preform 14. For example, such a surface may prevent material from adhering to the roller, and the roller may provide the material with a smooth surface.

In some embodiments, it is possible to control the temperature of the roller 90. This can be accomplished by heating the roller 90 itself or placing the roller 90 in a temperature-controlled environment.

Additionally, in some embodiments, the roller 90 may be provided with surface features 92. The surface features 92 may guide and/or control the preform 14 in one or more directions as the preform 14 passes over the roller. For example, the surface features 92 may be provided to prevent the preform 14 from folding over on itself as it passes over the roller 90. Thus, the surface features 92 may guide and control deformation of the preform 14 in the cross-machine direction (CD) relative to the machine direction A or in a direction perpendicular to the machine direction A. Thus, as the preform passes over the roller 90 in the CD A, the preform may be pushed together in the CD rather than folding over on itself.

In some embodiments, tension adjustment devices may be provided in communication with the rollers. These devices may be used to apply tension to the preform 14 in the machine direction, cross-machine direction, and/or vertical direction as the rollers move to further guide and/or control the preform.

As noted above, a coating may also be applied to the resulting strip to protect it from environmental conditions and/or improve wear resistance. For example, referring again to FIG. 7 , such a coating may be applied by introducing the thermoplastic resin into the coating die 72 via the extruder 72 oriented at any desired angle. To help prevent galvanic reactions, the coating material advantageously has a dielectric strength of at least about 1 kV per millimeter (kV/mm), in some embodiments, at least about 2 kV/mm, in some embodiments, from about 3 kV/mm to about 50 kV/mm, and in some embodiments, from about 4 kV/mm to about 30 kV/mm, as determined, for example, in accordance with ASTM D 149-09. For this purpose, suitable thermoplastic polymers may include, for example, polyolefins (e.g., polypropylene, propylene-ethylene copolymers, etc.), polyesters (e.g., polybutylene terephthalate (PBT)), polycarbonates, polyamides (e.g., Nylon ^™ ), polyetherketones (e.g., polyetheretherketone (PEEK)), polyetherimides, polyarylketones (e.g., polyphenylenedione (PPDK)), liquid crystal polymers, polyaryl sulfides (e.g., polyphenylene sulfide (PPS), poly(diphenylene sulfide ketone), poly(phenylene sulfide diketone), poly(diphenylene sulfide)), etc.), fluoropolymers (e.g., polytetrafluoroethylene-perfluoromethyl vinyl ether polymer, perfluoro-alkoxyalkane polymer, tetrafluoroethylene polymer, ethylene-tetrafluoroethylene polymer, etc.), polyacetals, polyurethanes, polycarbonates, styrenic polymers (e.g., acrylonitrile butadiene styrene (ABS)), acrylic polymers, polyvinyl chloride (PVC), etc. Particularly suitable high dielectric strength cover layer materials may include polyketones (eg, polyetheretherketone (PEEK)), polysulfides (eg, polyarylene sulfide), or mixtures thereof.

The cover layer may generally be "free" of continuous fibers. That is, the cover layer may contain "less than about 10 weight percent continuous fibers, in some embodiments, about 5 weight percent or less continuous fibers, and in some embodiments, about 1 weight percent or less continuous fibers (e.g., 0 weight percent). However, the cover layer may contain other additives to improve the final properties of the composite core. Additives used at this stage may include those that are not suitable for introduction into the continuous fiber material. For example, it may be beneficial to add a pigment to reduce finishing labor, or it may be beneficial to add a flame retardant to improve the flame retardancy of the core. Since many additives may be heat sensitive, excessive heat may cause them to decompose and produce volatile gases. Therefore, if a heat sensitive additive is extruded with the impregnating resin under high heat conditions, the result may be complete decomposition of the additive. Additives may include, for example: mineral reinforcements, lubricants, flame retardants, blowing agents, foaming agents, agent), UV resistant agent, heat stabilizer, pigment and combination thereof. Suitable mineral reinforcing agents may include, for example, calcium carbonate, silica, mica, clay, talc, calcium silicate, graphite, calcium silicate, aluminum hydroxide, barium ferrite and combination thereof.

Although not shown in detail herein, the coating die 72 may include various features known in the art to help achieve the desired application of the covering layer. For example, the coating die 72 may include an inlet guide component that aligns the incoming strip material. The coating die may also include a heating device (e.g., a heating plate) that preheats the strip material before applying the covering layer to help ensure sufficient adhesion. After coating, the formed part 15 can then be finally cooled using a cooling system 80 known in the art. The cooling system 80 can be, for example, a sizing system containing one or more blocks (e.g., aluminum blocks) that can completely encapsulate the composite core while vacuum-pulling the hot shape against the wall of the composite core as the composite core cools. A cooling medium (e.g., air or water) can be provided in the sizer to solidify the composite core into the appropriate shape.

Even if a shaping system is not used, it may be advantageous to cool the composite core after it exits the coating die (or, if no cover layer is applied, the merging die or calibration die). Cooling can be performed using any technique known in the art, such as a water box, a stream of cold air or air jets, cooling jackets, internal cooling channels, coolant circulation channels, and the like. Regardless, the temperature used to cool the material can be controlled to achieve a composite with specific mechanical properties, part dimensional tolerances, good processability, and aesthetics. For example, if the temperature of the cooling station is too high, the material may expand during cooling and interrupt the process. For semicrystalline materials, too low a temperature can also cause the material to cool too quickly and not fully crystallize, thereby adversely affecting the mechanical and chemical resistance properties of the composite. Multiple cooling die sections with independent temperature control can be used to advantageously balance processing and performance attributes. For example, in one particular embodiment, a water box with a temperature of about 0°C to about 30°C can be used, in some embodiments, a temperature of about 1°C to about 20°C, and in some embodiments, a temperature of about 2°C to about 15°C.

If desired, one or more sizing blocks (not shown) may be used, for example, after coating. These blocks may contain openings cut to the precise core shape, gradually graduating from an initial oversize to the final core shape. As the composite core passes through this, any tendency of the composite core to move or sag may be alleviated, and it may be pushed back (repeatedly) to the correct shape. Once shaped, in a continuous process, the composite core may be cut to the desired length at a cutting station (not shown) using, for example, a cutting saw capable of cross-sectioning, or the composite core may be wound on a reel. The length of the strip material and/or composite core may be limited to the length of the fiber bundle.

As will be appreciated, as the strip or composite core advances through any portion of the system of the present invention, its temperature can be controlled to achieve specific manufacturing and final composite material properties. The temperature of any or all component parts can be controlled using electric cartridge heaters, circulating fluid cooling, or any other temperature control device known to those skilled in the art.

Referring again to FIG. 7 , a pulling device 82 may be installed downstream of the cooling system 80 to pull the final composite core 16 through the system for final shaping the composite material. The pulling device 82 may be any device capable of pulling the core through the processing system at a desired rate. Typically, the pulling device may include, for example, a caterpillar puller and a reciprocating puller.

One embodiment of a composite core (or composite strand) formed by the above method is shown in more detail in FIG8 as element 516. As shown, the composite core 516 can have a substantially circular shape and can include a strip material (or fiber core) 514 containing one or more merged strips (continuous fiber components). "Substantially circular" generally means that the aspect ratio (height divided by width) of the core is typically from about 1.0 to about 1.5, and in some embodiments, is about 1.0. Due to selective control of the processes for impregnating the rovings and forming the merged strips, as well as the processes for compressing and forming the strips, the composite core can include a relatively uniform distribution of thermoplastic matrix along its entire length. It also means that the continuous fibers can be distributed in a generally uniform manner around the longitudinal center axis "L" of the composite core 516. For example, as shown in FIG8, the strip material 514 of the composite core 516 can include continuous fibers 526 embedded in a thermoplastic matrix 528. The fibers 526 can be generally evenly distributed around the longitudinal axis "L". It will be understood that only a small number of fibers are shown in FIG. 8 and that the composite core may typically contain a much larger number of evenly distributed fibers.

The cover layer 519 may also extend around the perimeter of the strip 514 and define the outer surface of the composite core 516. The cross-sectional thickness of the strip 514 may be strategically selected to help the composite core achieve a specific strength. For example, the thickness (e.g., diameter) of the strip 514 may be from about 0.1 to about 40 mm, in some embodiments, from about 0.5 to about 30 mm, and in some embodiments, from about 1 to about 10 mm. The thickness of the cover layer 519 may depend on the intended function of the part, but is typically from about 0.01 to about 10 mm, and in some embodiments, from about 0.02 to about 5 mm. The total cross-sectional thickness (or height) of the composite core 516 may also be from about 0.1 to about 50 mm, in some embodiments, from about 0.5 to about 40 mm, and in some embodiments, from about 1 to about 20 mm (e.g., diameter if circular in cross-section). Although the composite core may be substantially continuous in length, the length of the composite core may, in practice, be limited by the spool on which the composite core is wound and stored and/or by the length of the continuous fiber. For example, the length may typically be from about 1,000 m to about 5,000 m, although even longer lengths are of course possible.

By controlling the above-mentioned multiple parameters, a core with extremely high strength can be formed. For example, the composite core can exhibit a relatively high flexural modulus. The term "flexural modulus" generally refers to the ratio of stress to strain (in units of force per unit area) or the tendency of a material to bend during bending deformation. It is determined by the slope of the stress-strain curve produced by a "three-point bend" test (e.g., ASTM D790-10, Procedure A, room temperature). For example, the flexural modulus exhibited by the composite core of the present invention can be about 10 GPa or more, in some embodiments, from about 12 to about 400 GPa, in some embodiments, from about 15 to about 200 GPa, and in some embodiments, from about 20 to about 150 GPa.

According to certain embodiments disclosed herein, the ultimate tensile strength of the composite core used to produce the cable can be greater than about 300 MPa, for example, from about 400 MPa to about 50,00 MPa, or from about 500 MPa to about 3,500 MPa. Additionally, suitable composite cores can have an ultimate tensile strength of from about 700 MPa to about 3,000 MPa, or from about 900 MPa to about 1,800 MPa, or from about 1,100 MPa to about 1,500 MPa. The term "ultimate tensile strength" generally refers to the maximum stress that a material can withstand before breaking when stretched or pulled, and is the maximum stress reached on a stress-strain curve generated by a tensile test (e.g., ASTM D3916-08) at room temperature.

Additionally or alternatively, the composite core can have a tensile modulus of elasticity or elastic modulus of about 50 GPa to about 500 GPa, about 70 GPa to about 400 GPa, about 70 GPa to about 300 GPa, or about 70 GPa to about 250 GPa, and in certain embodiments, the composite core can have an elastic modulus of about 70 GPa to about 200 GPa, or about 70 GPa to about 150 GPa, or about 70 GPa to about 130 GPa. The term "tensile modulus of elasticity" or "elastic modulus" generally refers to the ratio of tensile stress to tensile strain and is the slope of a stress-strain curve generated by a tensile test (e.g., ASTM 3916-08) at room temperature.

Composite cores prepared according to the present disclosure may also have relatively high flexural fatigue life and may exhibit relatively high residual strength. Flexural fatigue life and residual flexural strength may be determined according to a "three-point bend fatigue" test (e.g., ASTM D790, typically at room temperature). For example, cores of the present invention may exhibit a residual flexural strength of about 60 kilograms per square foot ("ksi") to about 115 ksi, in some embodiments, from about 70 ksi to about 115 ksi, and in some embodiments, from about 95 ksi to about 115 ksi, after one million cycles under a load of 160 Newtons ("N") or 180 N. In addition, the cores may exhibit relatively minimal reduction in flexural strength. For example, a core having a porosity of about 4% or less, in some embodiments, about 3% or less, may exhibit a reduction in flexural strength of about 1% after a three-point bend fatigue test (e.g., from a maximum original flexural strength of about 106 ksi to a maximum residual flexural strength of about 105 ksi). Flexural strength may be tested before and after fatigue testing using, for example, the three-point bend test discussed above.

In some embodiments, the composite core can have a density or specific gravity of less than about 2.5 g/cm3, less than about 2.2 g/cm3, less than about 2 g/cm3, or less than about 1.8 g/cm3. In other embodiments, the composite core can have a density of from about 1 g/cm3 to about 2.5 g/cm3, or from about 1.1 g/cm3 to about 2.2 g/cm3, or from about 1.1 g/cm3 to about 2 g/cm3, or from about 1.1 g/cm3 to about 1.9 g/cm3, or from 1.2 g/cm3 to about 1.8 g/cm3, or from 1.3 g/cm3 to about 1.7 g/cm3.

In some cable applications, such as in overhead transmission lines, the strength-to-weight ratio of the composite core can be important. This ratio can be quantified as the ratio of the tensile strength of the core material to the density of the core material (in units of MPa/(g/cubic centimeter)). According to embodiments of the present invention, exemplary and non-limiting strength-to-weight ratios of the composite core can be from about 400 to about 1,300, from about 400 to about 1,200, from about 500 to about 1,100, from about 600 to about 1,100, from about 700 to about 1,100, from about 700 to about 1,000, or from about 750 to about 1,000. Again, this ratio is based on the tensile strength, MPa, and the composite core density, g/cubic centimeter.

In some embodiments, the composite core may have a percent elongation at break of less than 4%, less than 3%, less than 2%, while in other embodiments, the percent elongation at break may be from about 0.5% to about 2.5%, from about 1% to about 2.5%, or from about 1% to about 2%.

The coefficient of linear thermal expansion of the composite core can be less than about 5×10 ⁻⁶ /°C, less than about 4×10 ⁻⁶ /°C, less than about 3×10 ⁻⁶ /°C, or less than about 2×10 ⁻⁶ /°C (or expressed in m/m/°C). In other words, the coefficient of linear thermal expansion (in ppm per °C) can be less than about 5, less than about 4, less than about 3, or less than about 2. For example, the coefficient (ppm/°C) can be from about −0.4 to about 5, or from about −0.2 to about 4, or from about 0.4 to about 4, or from about 0.2 to about 2. The temperature range of the coefficient of linear thermal expansion can generally be in the range of −50°C to 200°C, the range of 0°C to 200°C, the range of 0°C to 175°C, or the range of 25°C to 150°C. The coefficient of linear thermal expansion is measured in the machine direction (i.e., along the length of the fiber).

The composite core also exhibits a relatively small "bend radius," which is the minimum radius to which a strip can be bent without damage and is a measure of the internal curvature of the composite core or composite strand. A smaller bend radius means the composite core can be more flexible and can be wound onto smaller diameter bobbins. This property also makes it easier to replace the composite core in currently used metal-core cables and allows for use with tools and installation methods currently used in conventional overhead transmission cables. In some embodiments, the composite core can have a bend radius of about 1 cm to about 60 cm, about 1 cm to about 50 cm, about 1 cm to about 50 cm, or about 2 cm to about 45 cm, as determined at a temperature of about 25°C. In certain embodiments contemplated herein, the bend radius can be about 2 cm to about 40 cm, or about 3 cm to about 40 cm. In other embodiments, the achievable bend radius, as determined at a temperature of about 25°C, is less than about 40 times the composite core's outer diameter, in some embodiments, from about 1 to about 30 times the composite core's outer diameter, and in some embodiments, from about 2 to about 25 times the composite core's outer diameter.

Significantly, the strength, physical and thermal properties of the composite core described above can also be maintained over a fairly wide temperature range, for example, from about -50°C to about 300°C, from about 100°C to about 300°C, from about 110°C to about 250°C, from about 120°C to about 200°C, from about 150°C to about 200°C, or from about 180°C to about 200°C.

The composite core may also have a low porosity, for example, about 6% or less, in some embodiments about 3% or less, in some embodiments about 2% or less, in some embodiments about 1% or less, and in some embodiments about 0.5% or less. Porosity can be determined as described above, for example, using a "resin burnout" test according to ASTM D 2584-08 or using computed tomography (CT) scanning equipment, such as a Metrotom 1500 (2k×2k) high resolution detector.

In one embodiment, the composite core of the present invention may be characterized by an ultimate tensile strength of about 700 MPa to about 3,500 MPa, an elastic modulus of about 70 GPa to about 300 GPa, and a coefficient of linear thermal expansion (ppm per ° C) of about -0.4 to about 5. Additionally, the composite core may have a density of less than about 2.5 g/cm3 and/or a strength-to-weight ratio (MPa/(g/cm3)) of about 500 to about 1,100. Additionally, in certain embodiments, the composite core may have a bend radius of about 1 cm to about 50 cm. Still further, the composite core may have an elongation at break of less than about 3%.

In another embodiment, the composite core of the present invention may be characterized by an ultimate tensile strength of about 1,100 MPa to about 1,500 MPa, an elastic modulus of about 70 GPa to about 130 GPa, and a coefficient of linear thermal expansion (ppm per °C) of about 0.2 to about 2. Additionally, the composite core may have a density of about 1.2 g/cm³ to about 1.8 g/cm³ and/or a strength-to-weight ratio (MPa/(g/cm³)) of about 700 to about 1,100. Furthermore, in certain embodiments, the composite core may have a bending radius of about 2 cm to about 40 cm. Furthermore, the composite core may have an elongation at break of about 1% to about 2.5%.

As will be appreciated, the specific composite core embodiments described above are merely illustrative of the various designs possible within the scope of the present invention. Among the various possible composite core designs, it will be appreciated that additional layers of material other than those described above may be used. For example, in certain embodiments, a multi-component core may advantageously be formed in which one component comprises a higher strength material and another component comprises a lower strength material. Such a multi-component core may be particularly useful for increasing the overall strength of the entire core without requiring more expensive high-strength materials. The lower and/or higher strength components may comprise strips comprising continuous fibers embedded in a thermoplastic matrix.

In addition, it should be understood that the scope of the present invention is in no way limited to the above-described embodiments. For example, the composite core may include a variety of other components depending on the desired application and the required performance. The additional components may be formed from continuous fibers, such as those described herein, and other materials. For example, in one embodiment, the composite core may include layers of discontinuous fibers (short fibers, long fibers, etc.) to improve its transverse strength. The direction of the discontinuous fibers may be adjusted so that at least a portion of these fibers are arranged at an angle relative to the direction of the continuous fibers.

cable

According to an embodiment of the present invention, a cable of the present invention (e.g., a high-voltage overhead transmission line) may comprise a cable core comprising at least one composite core and a plurality of conductive elements surrounding the cable core. The cable core may be a single composite core incorporating any of the composite core designs and accompanying physical and thermal properties provided above. Alternatively, the cable core may comprise two or more composite cores or composite strands having the same or different designs and having the same or different physical and thermal properties. These two or more composite cores may be assembled parallel to each other (straight line) or stranded, for example, around a central composite core member.

Thus, in some embodiments, the cable may comprise a cable core comprising one composite core surrounded by a plurality of conductive elements, while in other embodiments, the cable may comprise a cable core comprising two or more composite cores, the composite cores being surrounded by a plurality of conductive elements. For example, the cable core may comprise, for example, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20 composite cores, or more (e.g., 37 composite cores), each of which may incorporate any of the composite core designs and accompanying physical and thermal properties provided above. As will be appreciated by those skilled in the art, the composite cores may be arranged, bundled, or oriented in any suitable manner. For example, the composite cores may be twisted, e.g., the cable core may comprise 7 twisted composite cores or 19 twisted composite cores. Alternatively, the composite cores may be parallel, e.g., the cable core comprises a bundle of 7 composite cores arranged parallel to each other.

The cable may include a plurality of conductive elements surrounding the cable core (e.g., a single composite core, a plurality of twisted composite cores). The conductive elements may be of any geometric shape, such as round/circular wires or trapezoidal wires, and combinations thereof. The conductive elements may be one layer, two layers, three layers, four layers, or the like around the cable core. The conductive elements may be arranged in parallel with the cable core or in a spiral assembly or other suitable arrangement. Any number of conductive elements (e.g., wires) may be used, but the number of conductive elements in a cable may typically be as many as 84 conductive elements, typically 2 to about 50. For example, in some common conductor arrangements, 7, 19, 26, or 37 wires may be used.

Exemplary transmission cable designs having a composite core that may be used in various aspects of the present invention are described in US Pat. No. 7,211,319 to Heil et al., which is incorporated herein by reference in its entirety for all purposes.

Referring now to FIG. 9 , one embodiment of a cable 420 is shown. As shown, the cable 420 may include a plurality of conductive elements 422 (e.g., aluminum or its alloys) radially arranged around a generally cylindrical cable core 400, depicted as a single composite core, but which may be a plurality of twisted composite cores. The conductive elements may be arranged in a single layer or multiple layers. In the illustrated embodiment, the conductive elements 422 are arranged to form a first concentric layer 426 and a second concentric layer 428. The shape of the conductive elements 422 around the cable core 400 may vary. In the illustrated embodiment, the conductive elements 422 have a cross-sectional shape that is generally trapezoidal. Other shapes, such as circular, elliptical, rectangular, square, etc., may also be used. The conductive elements 422 may also be twisted or wound around the cable core 400 in any desired geometric configuration, such as in a spiral manner.

For example, referring to FIG. 10 , another embodiment of a power transmission cable 420 is shown. As shown, the power transmission cable 420 may include a plurality of conductive elements 422 (e.g., aluminum or an aluminum alloy) radially arranged around a bundle of generally cylindrical cable cores 400, which may be formed according to the present invention. FIG. 10 illustrates six composite cores 400 surrounding a single core 400, however, any suitable number of composite cores 400 in any suitable arrangement is within the scope and spirit of the present disclosure and may be used as a cable core. A covering layer 519 also surrounds the perimeter of each strip and defines the outer surface of each strip. The conductive elements may be arranged in a single layer or multiple layers. For example, in the illustrated embodiment, the conductive elements 422 are arranged to form a first concentric layer 426 and a second concentric layer 428. Of course, any number of concentric layers may be used. The shape of the conductive elements 422 may also be varied to optimize the number of elements that can be arranged around the cable core. For example, in the illustrated embodiment, the conductive elements 422 have a generally trapezoidal cross-sectional shape. Other shapes may also be used, such as circular, oval, rectangular, square, etc. The conductive elements 422 may also be twisted or wrapped around the cable core comprising the bundle of composite cores 400 in any desired geometric configuration, such as in a helical fashion.

The cross-sectional area of individual conductive elements can vary considerably, but generally, the cross-sectional area of an individual element can be from about 10 to about 50 mm ² , or from about 15 to about 45 mm ² . The total conductor area (kCMs) can be, for example, from about 167 to about 3500 kCMs, from about 210 to about 2700 kCMs, from about 750 to about 3500 kCMs, or from about 750 to about 3000 kCMs. Total conductor areas of about 795, about 825, about 960, and about 1020 kCMs are commonly used in many end uses of cables, such as overhead transmission lines. For example, a common steel-core aluminum stranded cable known in the industry is commonly referred to as a 795 kCM ACSR "Drake" conductor cable.

The outer diameter of the cable according to the present invention is not limited to any particular range. However, in general, the outer diameter of the cable can be, for example, from about 7 to about 50 mm, from about 10 to about 48 mm, from about 20 to about 40 mm, from about 25 to about 35 mm, or from about 28 to about 30 mm. Similarly, the cross-sectional area of the composite core in the cable is not limited to any particular range. However, the cross-sectional area of the composite core can be, for example, from about 20 to about 140 ^mm² , or from 30 to about 120 ^mm² .

The conductive element can be made of any suitable conductive or metallic material (including various alloys). The conductive element can include copper, a copper alloy, aluminum, an aluminum alloy, or a combination thereof. As used herein, "aluminum or aluminum alloy" is intended to collectively refer to a grade of aluminum or aluminum alloy having at least 97% by weight aluminum, at least 98% by weight aluminum, or 99% by weight aluminum, including pure aluminum or substantially pure aluminum. Aluminum alloys or grades of aluminum having an IACS conductivity of at least 57%, at least 58%, at least 59%, at least 60%, or at least 61% (e.g., 59% to 65%) can be used in the embodiments disclosed herein, and this includes any method that can produce such conductivity (e.g., annealing, tempering, etc.). For example, aluminum 1350 alloy can be used as the aluminum or aluminum alloy in certain embodiments of the present invention. Aluminum 1350, its composition, and its minimum IACS are described in ASTM B233, the disclosure of which is incorporated herein by reference in its entirety.

In some applications (e.g., overhead transmission lines), the sag of the cable can be an important characteristic. Sag is generally considered to be the distance the cable deviates from the straight line between the span endpoints. The sag on the tower span can affect the ground clearance and affect the height of the tower and the number of towers required. Sag generally increases with the square of the span distance, but can usually be reduced by increasing the tensile strength of the cable and/or reducing the weight of the cable. In some embodiments of the present invention, for NESC light load, the sag of the cable (rated temperature (180°C), 300 meter horizontal span) is about 3 to about 9.5m, about 4.5 to about 9.5m, about 5.5 to about 8m, or about 6 to about 7.5m. Similarly, for NESC heavy load, under similar conditions, the sag can be about 3 to about 9.5m, about 3 to about 7.5m, about 4.5 to about 7.5m, or about 5 to about 7m.

In some embodiments, the cable is further characterized by a stress parameter of about 10 MPa or greater, in some embodiments, about 15 MPa or greater, and in some embodiments, about 20 MPa to about 50 MPa. Methods for determining the stress parameter are described in detail in U.S. Patent No. 7,093,416 to Johnson et al., which is incorporated herein by reference in its entirety for all purposes. For example, sag and temperature can be measured and plotted as a sag versus temperature curve. The calculated curve can be fitted to the measured data using the Alcoa Sag 10 graphical method, which is available from Southwire Company (Carrollton, GA) under the trademark SAG 10 (Version 3.0, Update 3.10.10). The stress parameter is the fitting parameter labeled "Intrinsic Aluminum Stress" in SAG 10. If a material other than aluminum is used (e.g., an aluminum alloy), the stress parameter can be changed to fit the other parameters, and it adjusts the location of the inflection point on the expected curve, the amount of sag at high temperatures, and the state after the inflection point. Descriptions of stress parameters may also be provided in the Sag 10 Users Manual (Version 2.0), which is incorporated herein by reference in its entirety.

For the subject matter disclosed herein, creep is generally considered to be the permanent elongation of a cable under load over an extended period of time. The amount of cable length creep can be affected by factors such as the length of service, the load on the cable, the tension in the cable, and the temperature conditions to which it is subjected. It is contemplated that the cables disclosed herein may have 10-year creep values of less than about 0.25%, less than about 0.2%, or less than about 0.175% at 15%, 20%, 25%, and/or 30% RBS (rated breaking stress). For example, the 10-year creep value at 15% RBS may be less than about 0.25%, less than about 0.2%, less than about 0.15%, less than about 0.1%, or less than about 0.075%. The 10-year creep value at 30% RBS may be less than about 0.25%, less than about 0.225%, less than about 0.2%, or less than about 0.175%. These creep values are determined according to the 10-year ACSR Conductor Creep Test (Aluminum Association Creep Test rev. 1999), which is incorporated herein by reference in its entirety.

The maximum operating temperature of cables according to embodiments of the present invention may be up to about 300° C., up to about 275° C., or up to about 250° C. The maximum operating temperature of certain cables provided herein may be up to about 225° C., or up to 200° C., or up to 180° C., or up to 175° C. In various embodiments of the present invention, the maximum operating temperature may be from about 100 to about 300° C., from about 100 to about 250° C., from about 110 to about 250° C., from about 120 to about 200° C., or from about 120 to about 180° C.

According to some embodiments, it may be beneficial for the cable to have certain fatigue and/or vibration resistance properties. For example, the cable may pass (meet or exceed) the wind-induced vibration test specified in IEEE 1138 (which is incorporated herein by reference) for 100 million cycles.

In some embodiments, the cable may include a partial or complete layer of material between the cable core and the conductive elements. For example, the material may be conductive or non-conductive and may be a tape that partially or completely wraps around/covers the cable core. The material may be configured to hold or secure the individual composite core elements of the cable core together.

In some embodiments, the material may include metal or aluminum foil tape, polymer tape (e.g., polypropylene tape, polyester tape, Teflon tape, etc.), glass reinforced tape, etc. Typically, the material (e.g., tape) may have a thickness of about 0.025 mm to about 0.25 mm, but the thickness is not limited to this range.

In one embodiment, the tape or other material can be applied so that each subsequent turn overlaps the previous turn. In other embodiments, the tape or other material can be applied so that each subsequent turn leaves a gap between it and the previous turn. In other embodiments, the tape or other material can be applied so that there is no overlap and it abuts the previous turn without a gap. In these and other embodiments, the tape or other material can be applied spirally around the cable core.

In some embodiments, the cable may include a partial or complete coating of a material between the cable core and the conductive elements. For example, the material can be (or can include) a polymer. Suitable polymers can include, but are not limited to, polyolefins (e.g., polypropylene, propylene-ethylene copolymers, etc.), polyesters (e.g., polybutylene terephthalate (PBT)), polycarbonates, polyamides (e.g., Nylon ^™ ), polyetherketones (e.g., polyetheretherketone (PEEK)), polyetherimides, polyarylketones (e.g., polyphenylenedione (PPDK)), liquid crystal polymers, polyaryl sulfides (e.g., polyphenylene sulfide (PPS), poly(diphenylene sulfide ketone), poly(phenylene sulfide diketone), poly(diphenylene sulfide)), fluoropolymers (e.g., polytetrafluoroethylene-perfluoromethylvinyl ether polymers, perfluoro-alkoxyalkane polymers, tetrafluoroethylene polymers, ethylene-tetrafluoroethylene polymers, etc.), polyacetals, polyurethanes, styrenic polymers (e.g., acrylonitrile butadiene styrene (ABS)), acrylic polymers, polyvinyl chloride (PVC), etc., including combinations thereof. In some embodiments, the coating may be a coating of a cable core. In some embodiments, the coating may be a coating of a cable core having a plurality of layers. In some embodiments, the coating may be a coating of a cable core having a plurality of layers. In some embodiments, the coating may be a coating of a cable core having a plurality of layers. In some embodiments, the coating may be a coating of a cable core having a plurality of layers. In some embodiments, the coating may be a coating of a cable core having a plurality of layers. In some embodiments, the coating may be a coating of a cable core having a plurality of layers. In some embodiments, the coating may be a coating of a cable core having a plurality of layers.

Where the cable core comprises two or more composite cores (eg, composite strands), the coating may partially or completely fill the interstices between the individual core elements.

The present invention also encompasses methods for preparing cables comprising a cable core and a plurality of conductive elements surrounding the cable core. Generally, any suitable method known to those skilled in the art can be used to produce cables comprising various cable core arrangements and conductor element arrangements disclosed herein. For example, a rigid frame twisting machine can be used that is capable of rotating a spool of composite core or strands to install the cable core. In some embodiments, the rigid frame twisting machine can twist all composite cores or strands except the untwisted central composite core once per machine rotation. Each successive layer on the central composite core can be closed with a circular die. After applying the final layer, the cable core comprising the composite core or strands can be fixed with tape or other materials. If tape is used, it can be applied with a coaxial tape machine. The resulting cable core with tape can be rolled up on a reel. The cable core can then be fed back by the same rigid frame twisting machine for applying a plurality of conductive elements around the cable core.

According to embodiments of the present invention, methods of transmitting electricity are provided herein. One such method of transmitting electricity may include: (i) installing a cable disclosed herein, e.g., comprising a cable core and a plurality of conductive elements surrounding the cable core, and (ii) transmitting electricity through the cable. Another method of transmitting electricity may include: (i) providing a cable disclosed herein, e.g., comprising a cable core and a plurality of conductive elements surrounding the cable wires, and (ii) transmitting electricity through the cable. In these and other embodiments, the cable, cable core, and conductive elements may be any of the cables, cable cores, and conductive elements disclosed herein. For example, the cable may include any of the composite cores described herein, i.e., one or more composite cores or strands.

Example:

The present invention is further illustrated by the following examples, which should not be construed as limiting the scope of the present invention in any respect. After reading the description herein, without departing from the spirit of the present invention or the scope of the appended claims, those skilled in the art will readily appreciate multiple other aspects of the present invention, embodiments, modifications, and equivalents thereof.

Example 1

Initially, two continuous fiber strips were formed using the extrusion system described above. The continuous fiber used was a carbon fiber roving (Toray T700SC, comprising 12,000 carbon filaments with a tensile strength of 4,900 MPa and a mass per unit length of 0.8 g/m), with each individual strip comprising four rovings. The thermoplastic polymer used to impregnate the fibers was polyphenylene sulfide (PPS) (PPS 205, from Ticona, LLC), which has a melting point of approximately 280°C. Each strip comprised 50% by weight carbon fibers and 50% by weight PPS. The strip thickness was approximately 0.18 mm, with a porosity of less than 1.0%. Once formed, the strips were then transported into a pultrusion line running at 20 feet per minute. Prior to forming, the strips were heated in an infrared oven (power setting 305). The heated strips were then fed to a merging die head with a circular channel, which received the strips and compressed them together to form the initial shape of the strips. Inside the die, the strips are maintained at a temperature of approximately 177°C. After merging, the resulting preform is then briefly cooled using an air ring/channel device that supplies ambient air at a pressure of 1 psig. The preform is then passed through a nip formed between two rollers before arriving at a calibration die for final shaping. Inside the calibration die, the preform is maintained at a temperature of approximately 140°C. After leaving the die, the profile is coated with polyetheretherketone (PEEK) with a melting point of 350°C. The average thickness of the covering layer is approximately 0.1 to 0.15 mm. The resulting part is then cooled using an air stream. The resulting composite core has an average outer diameter of approximately 3.4 to 3.6 mm and contains 45% by weight carbon fiber, 50% by weight PPS, and 5% by weight coating material.

To determine the strength properties of the composite core, a three-point bend test was conducted according to ASTM D790-10, Procedure A. The cradle and nose radius were 0.25 inches, the cradle span was 30 mm, the sample length was 2 inches, and the test speed was 2 mm/minute. The resulting flexural modulus was approximately 31 GPa, and the flexural strength was approximately 410 MPa. The part had a density of 1.48 g/cm ³ and a porosity of less than approximately 3%. The bend radius was 3.27 cm.

Example 2

Initially, two continuous fiber strips were formed using the extrusion system described above. The continuous fiber used was carbon fiber roving (Toray T700SC), with each individual strip containing four rovings. The thermoplastic polymer used to impregnate the fibers was PPS 205. Each strip contained 50% by weight carbon fiber and 50% by weight PPS. The strip thickness was approximately 0.18 mm, with a porosity of less than 1.0%. Once formed, the strips were then transported to a pultrusion line running at 20 feet per minute. Before forming, the strips were heated in an infrared oven (power setting 305). The heated strips were then transported to a merging die with a circular channel, which received the strips and compressed them together to form the initial shape of the strip. Within the die, the strips were maintained at a temperature of approximately 343°C. After merging, the resulting preform was then simply cooled with an air ring/channel device that supplied ambient air at a pressure of 1 psig. The preform was then passed through the nip formed between the two rollers and then arrived at a calibration die for final shaping. Inside the calibrated die, the preform is maintained at a temperature of approximately 140°C. After exiting the die, the profile is coated with PPS 320, which has a melting point of 280°C. The average thickness of the covering layer is approximately 0.1 to 0.15 mm. The resulting part is then cooled with an air stream. The resulting composite core has an average outer diameter of approximately 3.4 to 3.6 mm and comprises 45% by weight carbon fibers, 50% by weight PPS, and 5% by weight coating material.

To determine the strength properties of the composite core, a three-point bend test was conducted according to ASTM D790-10, Procedure A. The cradle and tip radii were 0.25 inches, the cradle span was 30 mm, the sample length was 2 inches, and the test speed was 2 mm/minute. The resulting flexural modulus was 20.3 GPa, and the flexural strength was approximately 410 MPa. The part had a density of 1.48 g/ ^cm³ and a porosity of less than approximately 3%. The bend radius was 4.37 cm.

Example 3

Initially, two continuous fiber strips were formed using the extrusion system described above. The continuous fiber used glass fiber roving (4588 from PPG, which contains E-glass filaments with a tensile strength of 2,599 MPa per unit length mass of 0.0044 pounds per yard (2.2 g/m)), and each individual strip contained two rovings. The thermoplastic polymer used to impregnate the fibers was polyphenylene sulfide (PPS) (205, from Ticona, LLC), which has a melting point of approximately 280°C. Each strip contained 56% by weight glass fiber and 44% by weight PPS. The strip thickness was approximately 0.18 mm and the porosity was less than 1.0%. Once formed, the strips were then transported into a pultrusion line running at 20 feet per minute. Prior to forming, the strips were heated in an infrared oven (power setting 330). The heated strips were then transported into a merging die with a circular channel that received the strips and compressed them together to form the initial shape of the strips. After merging, the resulting preform is briefly cooled with ambient air. It then passes through a nip formed between two rollers before reaching a calibrated die for final shaping. Inside the calibrated die, the preform is maintained at a temperature of approximately 275°C. After exiting the die, the profile is coated with 205. The average thickness of the cover layer is approximately 0.1 to 0.15 mm. The resulting part is then cooled with an air stream. The resulting composite core has an average outer diameter of approximately 3.4 to 3.6 mm and contains 50% by weight glass fiber and 50% by weight PPS.

To determine the strength properties of the composite core, a three-point bend test was conducted according to ASTM D790-10, Procedure A. The cradle and tip radii were 0.25 inches, the cradle span was 30 mm, the sample length was 2 inches, and the test speed was 2 mm/minute. The resulting flexural modulus was 18 GPa, and the flexural strength was approximately 590 MPa. The part had a porosity of 0%, and the bend radius was 1.87 cm.

Example 4

Initially, two continuous fiber strips are formed using the extrusion system described above. Continuous fiber uses glass fiber roving (4588), with each individual strip containing two rovings. The thermoplastic polymer used to impregnate the fibers is Nylon 66 (PA66), which has a melting point of approximately 250°C. Each strip contains 60% by weight glass fiber and 40% by weight Nylon 66. The strip thickness is approximately 0.18 mm and the porosity is less than 1.0%. Once formed, the strips are then fed into a pultrusion line running at 10 feet per minute. Before forming, the strips are heated in an infrared oven (power setting 320). The heated strips are then fed into a merging die with a circular channel that receives the strips and compresses them together while forming the initial shape of the strip. After merging, the resulting preform is then simply cooled with ambient air. The preform is then passed through a nip formed between two rollers before arriving at a calibration die for final forming. In the calibration die, the preform is maintained at a temperature of approximately 170°C. After exiting the die, the profile was coated with Nylon 66. The average thickness of the cover layer was approximately 0.1 to 0.15 mm. The resulting part was then cooled with an air stream. The resulting composite core had an average outer diameter of approximately 3.4 to 3.6 mm and comprised 53% by weight glass fiber, 40% by weight Nylon 66, and 7% by weight coating material.

To determine the strength properties of the composite core, a three-point bend test was conducted according to ASTM D790-10, Procedure A. The cradle and tip radii were 0.25 inches, the cradle span was 30 mm, the sample length was 2 inches, and the test speed was 2 mm/minute. The resulting flexural modulus was 19 GPa, and the flexural strength was approximately 549 MPa. The part had a porosity of 0%, and the bend radius was 2.34 cm.

Example 5

Form 8 cores of three batches with different porosity levels. For each strip material, two continuous fiber strips are initially formed with the extrusion system basically described above. Continuous fiber uses carbon fiber roving (Toray T700SC, which contains 12,000 carbon filaments with a tensile strength of 4,900 MPa and a unit length mass of 0.8 g/m), and each individual strip contains 4 rovings. The thermoplastic polymer used to impregnate the fiber is polyphenylene sulfide ("PPS") (PPS 205, from Ticona, LLC), which has a melting point of about 280 ° C. Each strip contains 50% by weight carbon fiber and 50% by weight PPS. The strip thickness is about 0.18 mm and the porosity is less than 1.0%. Once formed, the strip is then transported into a pultrusion line running at 20 feet per minute. Before forming, the strip is heated in an infrared oven (power setting 305). The heated strips are then fed into a merging die with a circular channel, which receives the strips and compresses them together, simultaneously forming the initial shape of the strip. Inside the die, the strips are maintained at a temperature of approximately 177°C. After merging, the resulting preform is then briefly cooled using an air ring/channel device that supplies ambient air at a pressure of 1 psig. The preform is then passed through a nip formed between two rollers before reaching a calibration die for final shaping. Inside the calibration die, the preform is maintained at a temperature of approximately 140°C. After leaving the die, the profile is coated with polyetheretherketone ("PEEK"), which has a melting point of 350°C. The average thickness of the cover layer is approximately 0.1 mm. The resulting composite core is then cooled using an air stream. The resulting composite core has an average outer diameter of approximately 3.5 mm and contains 45% by weight carbon fiber, 50% by weight PPS, and 5% by weight coating material.

The average porosity of the first batch of composite cores was 2.78%. The average porosity of the second batch of composite cores was 4.06%. The average porosity of the third batch of composite cores was 8.74%. Porosity measurements were performed using CT scanning. The core samples were scanned using a Metrotom 1500 (2k×2k) high resolution detector. Detection was performed using an enhanced analysis mode with a low probability threshold. Once the samples were scanned for porosity, Volume Graphics software was used to interpret the data from the 3D scans and calculate the void level in each sample.

To determine the flexural fatigue life and residual flexural strength of the strips, three-point flexural fatigue tests were conducted according to ASTM D790. The bracket span was 2.2 inches, and the sample length was 3 inches. Four composite cores from each batch were tested at a load of 160 Newtons ("N"), and another four samples from each batch were tested at a load of 180 N, representing approximately 50% and 55% of the initial (static) flexural strength of the cores, respectively. Each sample was tested at a frequency of 10 Hertz (Hz) for one million cycles.

Before and after fatigue testing, three-point bending tests were performed according to ASTM D790-10, Procedure A, to determine the initial and residual bending strength properties of the strips. The average initial and residual bending strengths of each batch were recorded at each load level. The initial bending strength of the third batch was 107 ksi, and the residual bending strength of the third batch was 75 ksi, resulting in a decrease of approximately 29%. The initial bending strength of the second batch was 108 ksi, and the residual bending strength of the second batch was 72 ksi, resulting in a decrease of approximately 33%. The initial bending strength of the first batch was 106 ksi, and the residual bending strength of the first batch was 105 ksi, resulting in a decrease of approximately 1%.

Example 6

Figure 15 shows a cable 520 produced in Example 6. 26 conductive elements 522 form a first layer 526 and a second layer 528. The cable core 500 is a strand of seven composite cores. A tape 530 between the cable core 500 and the conductive elements 522 partially covers the cable core 500 in a spiral arrangement.

The cable was produced as follows. Seven composite cores of approximately 3.5 mm in diameter were twisted together to form a stranded cable core with a lay length of 508 mm. The composite cores were similar to those produced in Example 1 above. The cable core was secured with aluminum foil tape laminated to a glass fiber sheet and a silicone-based adhesive. 26 conductor wires were placed in two layers above and around the cable core and adhesive tape as shown in Figure 15. The conductor wires were approximately 4.5 mm in diameter and were made of fully annealed 1350 aluminum. The ultimate tensile strength of the cable was approximately 19,760 psi (136 MPa).

Example 7

Figure 15 shows a cable 520 produced in Example 7. 26 conductive elements 522 form a first layer 526 and a second layer 528. The cable core 500 is a strand of seven composite cores. A tape 530 partially covers the cable core 500 in a spiral arrangement between the cable core 500 and the conductive elements 522.

The cable was produced as follows. Seven composite cores of approximately 3.5 mm diameter were twisted together to form a stranded cable core with a lay length of 508 mm. The composite cores were similar to those produced in Example 1 above. The cable core was secured with aluminum foil tape laminated to a glass fiber sheet and a silicone-based adhesive. 26 conductor wires were placed in two layers over and around the cable core and tape as shown in Figure 15. The conductor wires had a diameter of approximately 4.5 mm and were made of an aluminum alloy containing zirconium (approximately 0.2-0.33% zirconium). Figure 16 shows the stress-strain data for the cable of Example 7.

The fatigue and vibration resistance characteristics of the cable of Example 7 were tested according to the wind-induced vibration test specified in IEEE 1138. The cable of Example 7 passed the wind-induced vibration test for 100 million cycles.

The 10-year creep (elongation) values for the cable of Example 7 were estimated using a mathematical model based on an overhead transmission cable similar to that of Example 7. The 10-year creep values calculated at 15%, 20%, 25%, and 30% RBS (rated breaking stress) were approximately 0.054%, approximately 0.081%, approximately 0.119%, and approximately 0.163%, respectively.

Constructive Example 8

FIG17 shows a cable 620 produced in constructive embodiment 8. Twenty-six conductive elements 522 form a first layer 626 and a second layer 628. The cable core 600 is a twisted strand of seven composite cores. A tape 630 partially covers the cable core 500 in a spiral arrangement between the cable core 600 and the conductive elements 622.

The cable of FIG17 can be produced as follows. Seven composite cores of approximately 3.5 mm diameter can be twisted together to form a stranded cable core having a lay length of 508 mm. The composite core is similar to that produced in Example 1 above. The cable core is secured with aluminum foil tape laminated to a fiberglass sheet and a silicone-based adhesive. 26 conductor wires can be placed in two layers over and around the cable core and tape as shown in FIG17. The conductors can be trapezoidal wires having a cross-sectional area of approximately 15 to 17 ^mm² and can be made from annealed 1350 aluminum (or an aluminum alloy containing zirconium).

Claims (20)

1. A cable comprising: (a) A cable core comprising at least one composite core, the composite core comprising: (i) at least one strip comprising a plurality of merged thermoplastic-impregnated rovings, the rovings comprising longitudinally oriented continuous fibers and a thermoplastic matrix embedded therein, the ratio of the ultimate tensile strength of the fibers to the mass per unit length being greater than 1,000 MPa/g/m, wherein the strip comprises 30% to 75% by weight of fibers and 25% to 70% by weight of the thermoplastic matrix, and wherein the thermoplastic matrix comprises polyphenylene sulfide; and (ii) A covering layer surrounding the at least one strip, wherein the covering layer comprises polyetheretherketone and contains less than 5% by weight of continuous fibers; The composite core has a flexural modulus of 15 GPa to 200 GPa; and (b) A plurality of conductive elements surrounding the cable core. 2. The cable according to claim 1, wherein: The strip material comprises 2 to 20 rovings; and Each roving contains 1,000 to 100,000 individual continuous fibers. 3. The cable according to claim 1, wherein the cable core comprises two or more composite cores. 4. The cable according to claim 1, wherein the cable core comprises 2 to 37 composite cores. 5. The cable according to claim 1, further comprising: A partial or complete strip layer between the cable core and the plurality of conductive elements; A partial or complete coating of the material between the cable core and the plurality of conductive elements; or It has both. 6. The cable of claim 1, wherein the cable comprises 2 to 50 conductive elements. 7. The cable of claim 1, wherein the cable comprises 7, 19, 26 or 37 conductive elements. 8. The cable according to claim 1, wherein the cable core is a stranded core comprising 2 to 37 composite cores, and the conductive elements are arranged in 2, 3 or 4 layers around the cable core. 9. The cable according to claim 1, wherein: The conductive element comprises copper, copper alloys, aluminum, aluminum alloys, or any combination thereof; and The conductive element has a circular or trapezoidal cross-sectional shape. 10. The cable of claim 1, wherein the conductive element comprises aluminum or an aluminum alloy with an IACS conductivity of 59% to 65%. 11. A cable comprising: (a) A cable core comprising at least one composite core, the composite core comprising: (i) at least one strip comprising a plurality of merged thermoplastic-impregnated rovings, the rovings comprising longitudinally oriented continuous carbon fibers and a thermoplastic matrix embedded therein, the ratio of ultimate tensile strength to mass per unit length of the carbon fibers being greater than 1,000 MPa/g/m, wherein the thermoplastic matrix comprises polyarylate sulfide, and wherein the strip comprises 30% to 75% by weight of carbon fibers and 25% to 70% by weight of the thermoplastic matrix; and (ii) A covering layer surrounding the at least one strip, wherein the covering layer comprises less than 1% by weight of continuous fibers and comprises polyetheretherketone and at least one additive material comprising mineral reinforcing agents, lubricants, flame retardants, foaming agents, foaming agents, UV resistant agents, heat stabilizers, pigments, and combinations thereof. The composite core has a flexural modulus of 15 GPa to 200 GPa; and (b) A plurality of conductive elements surrounding the cable core. 12. The cable of claim 11, wherein the at least one additive material comprises a mineral reinforcing agent, a UV resistant agent, a pigment, or a combination thereof. 13. The cable of claim 11, wherein the covering layer does not contain continuous fibers. 14. The cable of claim 11, wherein the cable core comprises two or more composite cores. 15. The cable of claim 11, wherein the cable core comprises 2 to 37 composite cores. 16. The cable of claim 11, further comprising: A partial or complete strip layer between the cable core and the plurality of conductive elements; A partial or complete coating of the material between the cable core and the plurality of conductive elements; or It has both. 17. The cable of claim 11, wherein the cable comprises 2 to 50 conductive elements. 18. The cable of claim 11, wherein the cable comprises 7, 19, 26 or 37 conductive elements. 19. The cable of claim 11, wherein the conductive element comprises copper, copper alloy, aluminum, aluminum alloy, or any combination thereof. 20. The cable of claim 11, wherein the conductive element comprises aluminum or an aluminum alloy with an IACS conductivity of 59% to 65%.