SYSTEM AND METHOD OF MANUFACTURING A COMPOSITE CORE FOR AN ELECTRICAL TRANSMISSION CABLE

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application claims priority from U.S. Provisional App. Serial No. 63/019282, filed May 2, 2020, entitled SYSTEM AND METHOD OF MANUFACTURING A COMPOSITE CORE FOR AN ELECTRICAL TRANSMISSION CABLE, the entire specification of which is hereby incorporated by reference in its entirety.

[0002] This application makes reference to and is related to (but does not claim priority from) from U.S. Patent Application Serial No. 12/070,244, filed February 15, 2008, entitled “Electrical Conductor and Core for An Electrical Conductor”, now U.S. Patent No. 7,705,242 issued April 27, 2010, the entire specification of which is hereby incorporated by reference.

BACKGROUND OF THE DISCLOSURE

[0003] 1. Field of the Disclosure

[0004] The disclosure relates in general to electrical transmission and distribution cables, and more particularly, to a system and a method for manufacturing a composite core for use in an electrical transmission and distribution cable.

[0005] 2. Background Art

[0006] The demand for transmission and distribution cables increases with the greater demand for electricity. As the appetite for power increases, new electrical cables continue to be installed. Additionally, to increase capacity, existing electrical installations are rewired with cables of greater capacity.

[0007] Traditionally, such electrical cables comprise a central stranded steel core which is wrapped in a stranded aluminum conductor. Such cables have been utilized for decades with very little change. Amongst other drawbacks, such cables are susceptible to excessive sag in certain climates and under certain operating conditions. Furthermore, such cables are susceptible to corrosion in other environments.

[0008] To combat the shortcomings, other composite based solutions have been developed. Certain such solutions are described in U.S. Pat. No. 7,060,326; U.S. Pub. Nos. 2004- 0131834; 2004-0131851; 2005-0227067; 2005-0129942; 2005-0186410; 2006-0051580; U.S. Prov. Pat. App. No. 60/374,879; and PCT Pub. No. WO 03/091008, the entire disclosures of each of the foregoing are incorporated herein by reference in their entirety. Additionally, the above incorporated patent likewise proposes a solution.

[0009] While these solutions have been improvements, it has been difficult to achieve improvements with respect to uniformity of cross-sectional configurations and uniformity along a length of the formed cores for such electrical cables. This is especially difficult where different fibers (and potentially different resins) are utilized.

[0010] One solution that has been offered is disclosed in the above-identified incorporated patent, namely, the ‘242 patent. While the approach disclosed utilizing what has been termed a lost mandrel approach has greatly enhanced uniformity of the pultruded cores when multiple different materials and fibers are utilized, there is nevertheless room for further improvement as to the systems and manufacturing of such fibers (along with other types of fiber cross-sectional configurations). It is desirable to further enhance the uniformity and improve the characteristics of the resulting cores that are to be utilized in electrical transmission and distribution cables. SUMMARY OF THE DISCLOSURE

[0011] In one aspect of the disclosure, the disclosure is directed to a system for manufacturing a composite core for an electrical cable comprising a fiber creel assembly, an alignment bushing system, a wet out tank, a curing die and a pultrusion assembly. The alignment bushing is positioned downstream of the fiber creel assembly includes a first bushing, a second bushing and a third bushing. The first bushing includes a plurality of openings arranged as a matrix. A second bushing is positioned downstream of the first bushing. The second bushing includes a plurality of openings in a radial and circular configuration, with a central lost mandrel inner core opening. The third bushing is positioned downstream of the second bushing. The third bushing has a central opening and a plurality of radial openings. The central elongated bushing member corresponds to the central opening. The wet out tank positioned between the first bushing and the second bushing. A curing die is positioned after the alignment bushing system. The pultrusion assembly is positioned downstream of the curing die.

[0012] In some configurations, the central elongated bushing member of the third bushing is heated.

[0013] In some configurations, the third bushing has a thickness and the central elongated bushing member has a length. The length of the central elongated bushing member is greater than the thickness of the third bushing.

[0014] In some configurations, the openings of the first bushing are generally parallel to each other.

[0015] In some configurations, the openings of the second gushing are positioned concentrically with respect to the central lost mandrel inner core opening.

[0016] In some configurations, the elongated bushing member of the third bushing extends away from the third bushing and toward the second bushing.

[0017] In some configurations, the openings of the second bushing are generally parallel to each other. [0018] In some configurations, the central opening of the third bushing is larger than a diameter of a resulting core.

[0019] In some configurations, the wet out tank further includes a resin recirculation loop.

[0020] In some configurations, the resin recirculation loop further includes resin inlet, a resin outlet, and a recirculating pump. The inlet and outlet are in fluid communication with an inner tank of the wet out tank.

[0021] In some configurations, the wet out tank further includes a heating assembly.

[0022] In some configurations, the heating assembly further includes an outer tank, a temperature control fluid, a climate control element and a recirculating pump. The recirculating pump is configured to circulate the temperature control fluid proximate the resin.

[0023] In some configurations, at least one post curing oven positioned downstream of the curing die.

[0024] In some configurations, the at least one post curing oven comprises at least two post curing ovens positioned sequentially downstream of the curing die [0025] In some configurations, the system further includes a coating system positioned downstream of the curing die.

[0026] In some configurations, the coating system includes a tank configured to retain a coating fluid.

[0027] In some configurations, the system further includes a coiling system configured to coil composite core after the pultrusion assembly.

[0028] In some configurations, the system further comprises a post cure oven structurally configured to receive composite core from the coiling system.

[0029] In another aspect of the disclosure, the disclosure is directed to a system for manufacturing a composite core for an electrical cable comprising a fiber creel assembly, an alignment bushing, a wet out tank, a curing die, a coating system, at least one heating oven, a pultrusion assembly, a coiling system and a post curing oven. The alignment bushing system is positioned downstream of the fiber creel assembly and includes a first bushing, a second bushing and a third bushing. The first bushing includes a plurality of openings arranged as a matrix. The second bushing positioned downstream of the first bushing. The second bushing includes a plurality of openings in a radial and circular configuration, with a central lost mandrel inner core opening. The third bushing is positioned downstream of the second bushing. The third bushing has a central opening and a plurality of radial openings. The central elongated bushing member corresponds to the central opening. The wet out tank is positioned between the first bushing and the second bushing. The curing die is positioned after the alignment bushing system. The coating system is positioned downstream of the curing die. The at least one heating oven positioned downstream of the coating system. The pultrusion assembly is positioned downstream of the at least one heating oven. The coiling system configured to coil composite core after the pultrusion assembly. The post curing oven spaced apart from the coiling system, the post curing oven configured to receive composite core from the coiling system.

[0030] The method of manufacturing a composite core for an electrical cable comprises the steps of: providing a plurality of fibers and a resin; aligning the fibers through an alignment bushing system; providing the resin to a wet out tank; pulling the fibers through the wet out tank; pulling the fibers with resin, through a curing die; at least partially curing the resin within the curing die; coiling the fibers and resin after the curing die; and placing the fibers and resin after the step of coiling, into a post curing oven.

[0031] In some configurations, the method further comprises the step of pulling the fibers through at least one oven after the step of curing the resin within the curing die.

[0032] In some configurations, the method further comprises the step of coating the fibers and the resin after the step of at least partially curing with a coating.

[0033] In some configurations, the step of aligning further comprises the steps of first aligning the fibers through a first bushing; second aligning the fibers through a second bushing positioned downstream of the first bushing; and third aligning the fibers through a third bushing. [0034] In some configurations, the step of pulling the resin through the wet out tank is done between the steps of first aligning and second aligning.

[0035] In some configurations, the step of coiling further comprises the step of coiling the fibers and resin about a drum.

BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The disclosure will now be described with reference to the drawings wherein:

[0037] Figure 1 of the drawings is a schematic representation of the system of the present disclosure;

[0038] Figure 2a of the drawings is a side elevational schematic representation of the fiber creel assembly of the present disclosure;

[0039] Figure 2b of the drawings is a top plan schematic representation of the fiber creel assembly of the present disclosure;

[0040] Figure 3 of the drawings is a perspective view of a spool retaining axle of the fiber creel assembly of the present disclosure;

[0041] Figure 4 of the drawings is a perspective view of the first bushing of the present disclosure; [0042] Figure 5 of the drawings is a perspective view of the second bushing of the present disclosure;

[0043] Figure 6 of the drawings is a perspective view of the third bushing of the present disclosure;

[0044] Figure 7 of the drawings is a side elevational view of the third bushing of the present disclosure;

[0045] Figure 8 of the drawings is a schematic top plan view of a configuration of the wet out tank of the present disclosure;

[0046] Figure 9 of the drawings is a perspective view of the coiling system with drum of the present disclosure; and

[0047] Figure 10 of the drawings is a perspective view of a schematic representation of a post cure oven of the present disclosure.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0048] While this disclosure is susceptible of embodiment in many different forms, there is shown in the drawings and described herein in detail a specific embodiment(s) with the understanding that the present disclosure is to be considered as an exemplification and is not intended to be limited to the embodiment(s) illustrated.

[0049] It will be understood that like or analogous elements and/or components, referred to herein, may be identified throughout the drawings by like reference characters. In addition, it will be understood that the drawings are merely schematic representations of the invention, and some of the components may have been distorted from actual scale for purposes of pictorial clarity.

[0050] Referring now to the drawings and in particular to Figure 1, the system for manufacturing a composite core for an electrical cable is shown generally at 10. The system includes a fiber creel assembly 12, alignment bushing system 13, wet out tank 14, curing die 15, coating system 16, pultrusion assembly 17, coiling system 18 and post cure oven 19. It will be understood that the pultrusion assembly 17 comprises pulling clamps and structures that are known to one of skill in the art as pultrusion equipment, namely, equipment that can pull a tow of fibers through a die and direct them generally linearly along a pultrusion table. It will be understood that the manner in which such fiber tows are pulled through a die and the particular clamping grasping and pulling mechanism can be varied and are known to those of skill in the art. Generally, as described herein, subsequent elements are understood to be “downstream” of prior elements in a progression from the fiber creel assembly to the coiling system and the post cure oven. [0051] The system is configured to form a core that can be used to support a conductor so as to form an electrical transmission and/or distribution cable. One such cable that may be formed is disclosed in the above-incorporated patents that have been cross referenced. Of course, other cores and configurations may also be formed. The present system provides for improved and consistent cross-section core to be manufactured that exhibits superior properties due to the level of control and the level of precision in the manufacturing process and due to the configuration of the system.

[0052] The fiber creel assembly 12 is shown in Figure 2a and 2b as comprising frame

20, spool retaining axle 22, spool tensioning assembly 24, dispensing rollers 26 and dispensing guides 28. The frame is an elongated member having a first side 30, a second side 31 and a dispensing end 32. A plurality of spool retaining axles extend outwardly from each of the first side and the second side of the frame 20. As will be understood, each spool retaining axle is configured to retain a spool of fiber, such as spool 313. In the configuration shown, a matrix of spool retaining axles are provided that include 28 columns and 7 rows each of which can receive a fiber spool 313. It will be understood that a number of different configurations are contemplated and matrices of different sizes can be utilized. In the configuration shown, the spool retaining axles are generally parallel to the ground surface and generally perpendicular to the frame from which the axles extend, while variations are contemplated.

[0053] Each of the spools may include a clutch or a delay structure in the form of a spool tensioning member 24 so as to provide tension on each of the fibers that are pulled from the fiber spool 313. In particular, it is contemplated that the spool tensioning assembly can resist rotation and therefore apply a tension when the fibers are pulled from the fiber spool 313. It is contemplated that the tension may be between 1 and 500 grams of tension. It is contemplated that the tension is generally maintained as the fiber is pulled from the spool and is preferably constant throughout the spool as the fiber is removed. That is, the tension preferably remains the same as the spool is depleted of fiber. Variations are contemplated between different fiber spools, while it is likewise contemplated that all spools may be or groups of spools may be at substantially identical tensions.

[0054] The fibers when pulled can ride along the length of the frame and through dispensing rollers 26 and dispensing guides 28. In the configuration shown, a plurality of structures is provided along the frame with the dispensing rollers 26 and dispensing guides 28 being positioned at the dispensing end 32.

[0055] The alignment bushing system 13 comprises a set of three bushings that are spaced apart from each other and positioned between the dispensing end 32 of the frame of the fiber creel assembly 12 and the curing die 15. These bushings include first bushing 60, second bushing 70 and third bushing 80. In the configuration shown, the first bushing 60 is positioned before the wet out tank 14 with the second bushing 70 and third bushing 80 being positioned after the wet out tank 14.

[0056] In the configuration shown, the first bushing includes first side 61 (which is the incoming side) and second side 62 with a plurality of openings extending through the bushing, such as opening 63. In the configuration shown, the openings 63 are arranged in a matrix of spaced apart rows positioned in vertical columns. This provides for vertical alignment of a plurality of fiber groupings, or tows. A central lost mandrel inner core opening 64 is centrally located within the bushing. In the configuration shown, the openings are substantially parallel to each other and substantially perpendicular to the surfaces defined by the first and second sides. In the configuration shown, this bushing may be formed from two substantially identical plates, or from a single plate of material. The first bushing is positioned proximate the inlet to the wet out tank 14 such that prior to entering the wet out tank, the fibers have been though the first bushing and have been initially aligned. It is further contemplated that the first bushing may be heated so as to heat the fibers that pass through the bushing prior to entering or as the fibers enter the wet out tank. In other configurations, a separate heater may be utilized to heat the fibers prior to entering the wet out tank.

[0057] The second bushing 70 includes first side 71 and second side 72 with openings extending therethrough, such as openings 73 along with a central lost mandrel inner core opening 74. In the configuration shown, the openings 73 are arranged in a radial and circular pattern radially outward from the central lost mandrel inner core opening 74 and generally centered about the central lost mandrel inner core opening 74. In the configuration shown, the openings are substantially parallel to each other and spaced apart from each other, and substantially perpendicular to the surfaces defined by the first side and the second side. Additionally, in the configuration shown, the openings are arranged in successively radially outward circular configurations centered about the central lost mandrel core opening. In the configuration shown, a total of four separate circles that extend radially outwardly are shown, with the inner most circle being radially spaced apart from the central lost mandrel inner core opening a distance substantially greater than the spacing between each successive circle of openings that extend radially outward therefrom.

[0058] The third bushing 80 includes bushing plate 81 and central elongated bushing member 86. The bushing plate 81 includes first side 82 and second side 83 with central opening 84 and radial openings 85. The central elongated bushing member 86 includes first end 87, second end 88 and opening 89. The first end 87 extends outwardly from the first side 82 of the bushing plate 81 and has a length that is greater than the thickness of the bushing plate 81, in the configuration shown. It is contemplated that the central elongated bushing member 86 may be heated so as to be at a temperature that is higher than ambient temperature.

[0059] It is contemplated that the radial openings 85 are radially spaced apart from the central opening 84 and generally centered about the central opening 84. The central opening 84 is generally sized larger than the resulting core that is produced, as there is shrinkage of resin that occurs during the curing process. For example, the central opening 84 may be 1-1.5% larger (or more generally 0.2% to 3% larger, preferably) than the resulting dimensions of the portion of the core proceeding therethrough (i.e., than the cured core portion that corresponds to the fibers passing through the central elongated bushing 86.

[0060] In the configuration shown, the central elongate bushing is heated such that the resin temperature is approximately 5 to 50F and more preferably 10F to 30F below the initial onset gel time of the resin system. A DSC test can be done on the resin mix and adjusting the drip off temperature from the central elongated bushing and adjusting accordingly. It has been found that the resin viscosity is lowered, thereby maximizing fiber wet out.

[0061] The wet out tank 14 is shown in Figure 8 as comprising inner tank 34, resin circulation loop 36 and heating assembly 38. The inner tank 34 includes fiber inlet 40 and fiber outlet 42. The inner tank 34 is configured to retain a quantity of resin so as to allow the fiber to pass through the inner tank and to be substantially completely wetted out and ready for processing in the die. The fiber inlet and the fiber outlet may be configured to minimize the loss of resin therethrough. And, it will be understood that the fibers may be bathed within the resin by submersion, by the resin being sprayed or dropped on the resin, or by any one of a number of different combinations of the foregoing, among others. In the configuration shown, the wet out tank is positioned between the first and second bushings.

[0062] The resin recirculation loop 36 comprises a resin inlet 44, a resin outlet 45, a circulating pump 46 and a secondary tank 47. Preferably, the resin is circulated between the inner tank 34 and the secondary tank 47 and back to the inner tank 34. It has been found that such recirculation reduces gel time drift and enhances viscosity uniformity. In the configuration shown, the circulation pump achieves such a circulatory effect. In other configurations, multiple pumps may be utilized between the inner tank and the secondary tank both for removing and for resupplying the resin to the inner tank.

[0063] The heating assembly 38, in the configuration shown, comprises an outer tank 50, a temperature control fluid 52, a climate control element 54 and a circulating pump 56. In the configuration shown, the temperature control fluid 52 comprises water, and the climate control element 54 heats the water or cools the water to maintain the water between, preferably 70F and 120F (of course, other temperature ranges are contemplated). The circulating pump 56 aids in maintaining uniformity of temperature within the outer tank 50. In other configurations, the body of the inner tank may be heated through conduction or convection directly through a heating or chilling element (such as an electrical structure) or through convection by having, for example, air directed onto or past the inner tank. In such a configuration, the outer tank can be removed, or, piping or the like (or a manifold) may be provided in its place.

[0064] Additionally, the inner tank may further include a heater so that the fibers can be heated prior to being wetted out within the wet out tank. In some configurations, the heater may be incorporated into the first bushing, while in others, the heater may be a separate structure positioned between the first bushing and the inner tank.

[0065] The curing die 15 comprises an elongated heated member having a first end 90, a second end 92, an opening 94 and a heating element 96. As will be understood to one of skill in the art, the opening 94 has a cross-sectional configuration that matches the desired properties of the core, and a length that provides for sufficient time for the resin to be cured sufficiently so as to maintain the desired shape of the core. It will be understood that the heating element 96 can control the heat that is applied to the resin and the core that is being pulled through the opening 94 between the first and second ends.

[0066] In the configuration shown, the curing die comprises a heated metal die, and more preferably, a 440C stainless steel material honed to a 60-61 RC hardness with the OD and ID and radius (R.25) dimensions and surface finish being at a tolerance of 0.25 to 8 micro inches and preferably 1 to 6 micro inches, and preferably at least 5 micro inches.

[0067] The coating system 16 is positioned downstream of the curing die 15 and includes tank 100, first fiber opening 102 and second fiber opening 104. In the configuration shown, the fiber is pulled through the first fiber opening 102 and into the tank 100 and then out through the second fiber opening 104. An acrylic material is positioned with the tank and applied to the outside of the forming and curing core. The heat of the core is sufficient to initiate the reaction so as to cure and solidify the acrylic material to the outside of the core.

[0068] A plurality of post curing ovens 19 may be provided. For example, a post cure inline oven 130a may be provided. The post cure oven 130a includes a first end 132, a second end 134 and a heating element 136. The post cure oven 130a, is positioned beyond the coating system and the curing die (or at least beyond the curing die) as the core is pulled along a post formation table (as one of skill in the art will understand is common with pultrusion equipment). In the configuration shown, the post cure oven 130a include a hinged portion so as to allow for access to the inner portions of the cover. In the configuration shown, the post cure oven 130a is 10 feet in length and is configured to heat the internal heated area to approximately 500F (while other temperatures are contemplated). Additionally, in the configuration shown, a total of three ovens are positioned in series, namely post cure ovens 130a, 130b and 130c. It will be understood that the ovens may be operated at different temperatures, the ovens may be of differing length and the ovens may be selectively energized depending on a number of different factors.

[0069] Additionally, it is contemplated that a coiling system 18 and additional post cure chamber 140 may be provided in some configurations. The coiling system is shown in Figure 4 as comprising drum axle 120, drum motor 122 and controller 124. This structure is configured for use in association with drum 320 which includes a pair of opposing side panels 322, 324 and a central cylinder 326 having an outer surface 328. The coiling system is configured to receive the drum 320 onto the drum axle 120 and then have the drum motor 122 wind the drum to coil up the cured (or at least partially cured) cable. Once coiled as desired (and it will be understood that the speed can be varied in the coiling process), the entire wound drum can be placed in a heated chamber (or oven) 140 as an entire coil at a desired temperature for a desired amount of time.

[0070] In operation, a user first provides the desired spools of fibers that will be used to form the core of the present disclosure. Once provided, these spools are coupled to the desired spool retaining axles of the fiber creel assembly. The individual spool fibers are then guided through the dispensing rollers and guides.

[0071] Once properly guided, the fibers are selectively and carefully placed through the openings of the first die. The particular patter and placement depends on the final fiber configuration of the core, the size of the core and other factors. Next, the fibers are directed through the wet out tank and then carefully through the proper openings in the second die. At the same time, the central core (where a lost mandrel process is utilized) is directed through the first bushing, the wet out tank and the second bushing.

[0072] Next, the fibers are directed through the proper openings on the third bushing, then through the curing die, the coating system, the ovens of the post cure oven system, and to the coiling system. The fibers are introduced to the pultrusion pulling system so as to be pulled through the process. In the configuration shown, the pultrusion pulling system comprises a plurality of clamping member that can linearly move along the path of the core and which can cooperate to hand off the core pulling duties between the clamping members.

[0073] Once the fiber is properly positioned, or at the same time, the resin is placed in the inner tank, and prepared so as to be recirculated within the resin recirculation loop. The bushings are heated as is the resin to operating temperatures. Furthermore, where utilized, the coating system tank 100 is filled with the proper acrylic material. [0074] Once the systems have been set, operation toward and into a steady state can be initiated. In particular, the pulling system pulls the fibers from the spools through the system. In the configuration shown, as the fibers are pulled, the fiber creel assembly provides the necessary tension to the fibers so that the desired level of tension of the fibers through the die can be set and maintained. The fibers proceed through the first die, they are heated and wetted out in the wet out tank. Next, they proceed through the second die along with the resin and the third die with the resin. Eventually, the fibers wetted out with resin are directed into the curing die. As the now formed core (which is still curing, but which has cured sufficient to maintain shape) exits the curing die, it may be directed through one or more post cure ovens and the coating system (to have an application of acrylic to the outer surface thereol). In some configurations, the coating system may be positioned before the ovens 130a through 130c, whereas in other configurations, the coating system may be positioned after the ovens 130a through 130c. In still other systems, a coating system may not be utilized. Similar with the post cure ovens, that is, in some configurations, they may be eliminated or not utilized.

[0075] The formed (and curing) core is then directed to the coiling system and coiled onto a drum. Once the drum is filled to the desired capacity, the drum can be placed into the chamber 140 for a desired time at a desired temperature. In other configurations, the use of a separate chamber or oven after coiling can be eliminated.

[0076] The foregoing description merely explains and illustrates the disclosure and the disclosure is not limited thereto except insofar as the appended claims are so limited, as those skilled in the art who have the disclosure before them will be able to make modifications without departing from the scope of the disclosure.