Abstract:
A system and method for additively manufacturing splices and terminations for extra high, high, medium and low voltage power cable includes providing an additive manufacturing machine having at least one print head. Cable ends can be secured within a chamber from which atmospheric air can be evacuated and replaced with non-oxidizing gas. A scanning device can determine the composition and position of the various constituents of the cable ends, from which information a controller can determine the printing sequence and print a termination or splice portion.

Description:
FIELD OF INVENTION 
     The present disclosure concerns termination and splicing of electrically conductive cables, and in particular low, medium, high, and extra high voltage cables. 
     BACKGROUND 
     Splicing and termination of low, medium, high, and extra high voltage electrical cables has involved preparing a single cable end in the case of termination, or preparing two cable ends in the case of splicing. Preparation of the cable ends included removing a part of each of the layers of the cables in a specific order and in specific amounts. The conductor in the cables was then crimped to a connector appropriately sized for the conductor. Next, rolls of tape, an engineered splice, or termination kit was used to build a splice or termination that would grade the electrical stress resulting from the structure of the prepared ends of the cables. Available kits can provide sufficient protection from the environment by at least partial reconstruction of certain layers of the cable or by providing at least functional replacement of the layers of the cable through a specialized joint or termination assembly. Installation of such splicing or termination kits or manual reconstruction of cable layers has required trained personnel to manually perform the required tasks, raising the potential for human error that could compromise the splice or termination. Furthermore, use of manual splicing and termination techniques can result in undesirably long and costly timeframes for completion. 
     SUMMARY 
     A system and method for additively manufacturing splices and terminations for extra high, high, medium and low voltage power cable includes providing an additive manufacturing machine having at least one print head. Cable ends can be secured in a chamber in which a controlled environment can be achieved including one evacuated of atmospheric air and filled with gasses, including but not limited to non-oxidizing gas and conductive gas, powder or a vacuum. A scanning device can determine the material and position of the various constituents of the cable ends, providing a map of the surface on which the termination or splice will be built. From the information gathered concerning the cable, a controller can determine the printing sequence and print a termination or splice portion. Robots can be incorporated with a variety of end effectors to perform manufacturing and finishing steps in addition to the additive printing. In addition to printing processes, other processes can be performed including but not limited to arc vapor deposition and electrostatic painting. Image information can be maintained for quality control purposes and for evaluation of the printing process, including during printing. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the accompanying drawings, structures and methods are illustrated that, together with the detailed description provided below, describe aspects of a system and method for automated splicing and terminating low, medium, high, and extra high voltage cables. It will be noted that a single component may be implemented as multiple components or that multiple components may be implemented as a single component. The figures are not drawn to scale and the proportions of certain parts have been exaggerated for convenience of illustration. Further, in the accompanying drawings and description that follow, like parts are indicated throughout the drawings and written description with the same reference numerals, respectively. 
         FIG. 1  illustrates a diagram of additive manufacturing system  100 . 
         FIG. 2  illustrates a process  200  for additively manufacturing a splice portion  115 . 
         FIG. 3  illustrates a diagram of additive manufacturing system  300 . 
         FIG. 4  illustrates a process  400  for additively manufacturing a termination  350 . 
     
    
    
     DETAILED DESCRIPTION 
     With reference to  FIG. 1 , an additive manufacturing system  100  includes an additive manufacturing machine  101  having multiple build heads  102   a - 102   e . Each of the build heads  102  can be selectively positioned to apply specific materials during additive manufacturing processes. As indicated by arrow  103 , the build heads  102  can be rotated into and out of printing position. In  FIG. 1 , build head  102   a  is in a printing position, from which position the particular build head  102  can apply a specific material during the operations described herein. Once the build head  102   a  has completed its allotted depositions of the splice or termination, build head  102   a  can be rotated out of the printing position and swapped with another of build heads  102   b - 102   e , which can be rotated into printing position. While  FIG. 1  depicts five build heads  102   a - 102   e , more or less than five build heads  102  can be implemented according to the present teachings, including a single build head capable of printing several different materials, including plastics and metals. The cables  104 ,  106  have terminal faces  108 ,  110 , disposed at ends  109 ,  111 , respectively. The ends  109 ,  111  are disposed in the chamber  112  of the machine  101  during the printing process. Chamber  112  is formed at least in part by selectively openable cover  113 , which allows access to the cable ends  109 ,  111 . Splicing chamber  112  can allow for a controlled environment, such as when atmospheric air is purged from the chamber  112  and replaced with inert gas such as nitrogen or argon gas in order to provide a non-oxidizing environment for printing to take place. Other forms of controlled environments can involve filling the chamber  112  with non-inert gases, liquids, solid powders, including powders that are consumed during the printing process, or a vacuum. According to one aspect of the present teachings, the cable terminal ends  109 ,  111  are cut to produce a face  108 ,  110  in preparation for material printing. In the illustrated case, the cuts form flat faces  108 ,  110  perpendicular to the longitudinal axis of the respective cable  104 ,  106  as it is aligned near ends  109 ,  111 . Such a square cut can prepare the ends  109 ,  111  of cables  104 ,  106  for the additive manufacturing processes described herein. In other alternatives according to the present teachings, faces having forms and shapes other than square faces can be cut from the cables ends  109 ,  111 , in preparation for printing, including but not limited to triangular cuts, V-shaped cuts or stair stepped cuts. 
     According to one aspect of the present teachings, the additive manufacturing machine  101  prints each of the layers of the cables  104 ,  106  in the gap between terminal ends  108 ,  110  to form a splice portion  115 . The machine  101  can start printing with the conductor  114 . After completion of the conductor  114  in the splice portion  115 , the machine  101  prints, in sequence and to completion, the conductor shield  116 , the insulation  118 , the insulation shield  120 , the shield metallic layer  122 , which can include reinforcing wires, and finally the outer jacket  124 . The same layers, having the same relative radial position and composition, are found in both illustrated cables  104 ,  106 . According to another aspect of the present teachings, the materials deposited by the respective build heads  102  of the machine  101  can be the same as the materials in the layers of cables  104 ,  106 . According to another aspect of the present teachings, heat or lasers can be applied to the deposited materials that require cross-linking, such as an insulation including cross-linked polymers, including but not limited to cross-linked polyethylene (XLPE). Heat or lasers can also be applied to melt any metals or plastics that require melting, which melting can include cross-linking plastics as necessary. Melting or cross-linking can occur as the respective materials are deposited between terminal ends  108 ,  110  to form splice portion  115 , or after some predetermined amount of the subject material is deposited. A laser or heat element included with the build heads  102 , or other heat source, can apply the necessary heat required to melt any deposited metal, such as the metal in conductor  114 , or activate a catalyst that causes the cross-linking of plastic materials. Materials including but not limited to conductors, ethylene propylene rubber (EPR), ethylene propylene diene monomer (EPDM), silicone, water swellable tapes, and other materials can be printed with build heads  102 . The ends  109 ,  111  of the cables can be secured to the machine  101  at securing members  126 ,  128 . The securing members can secure the cables  104 ,  106  to prevent both longitudinal movement and rotational movement. Prevention of rotational movement can be beneficial when the cables  104 ,  106  are not continuously symmetric about their radial center, such as a Milliken conductor or a trefoil conductor, which have an integer number of rotational degrees of symmetry. 
     A detection device  130  can be used to identify the various layers of the cables  104 ,  106 . Such a device  130  can, for example, include a position sensor in combination with imaging equipment, such as a multispectral cameras capable of capturing images in various electromagnetic spectral ranges, including infrared, ultraviolet, or visible light. Device  130  can also include a position sensor in combination with a display module permitting an operator to identify positions of various portions of the cables  104 ,  106 . Adjustments can be made to the positions and orientations of the cables  104 ,  106  based on the information obtained through use of the detection device  130 . The detection device  130  can move across the faces  108 ,  110 , as depicted by arrow  131 , in order to determine the positions of the various layers of the cables  104 ,  106 , effectively obtaining a map of the faces  108 ,  110 . The information concerning the composition and positions of the layers of cables  104 ,  106  can be supplied to controller  132 , which can be a general purpose computer or programmable logic controller (PLC) that can include non-transient memory, storage, processors, input and output ports, communications ports, and other components. It should be noted that other forms of computing devices can be implemented, such as a neural computer. The information concerning the positions and compositions of the layers of cables  104 ,  106  can be supplied to controller  132  through use of other devices, such as a measuring microscope, or a manually operated position detectors. Numerous forms of control of the printing sequence of operations can be implemented according to the present teachings, including but not limited to electromechanical and mechanical controllers. Control of the printing sequence can also be accomplished manually, including by manual input of all or a subset of the printing operations into controller  132 . According to another aspect of the present teachings, the controller  132  includes instructions to clean the machine  101 , including build heads  102 , before the printing process, during the printing process, after the printing process, or any combination of the three. 
     The controller  132  can also record and log imaging data. Controller  132  can include image processing equipment and software. Image data can be fed from detection device  130  to controller  132 , where it can be used in differentiating the layers of the cables  104 ,  106 , and also for quality control, such as in identifying voids or failed deposition. According to another aspect of the present teachings, image data logged over the printing process can be selectively viewed during or after the process in order to evaluate the printing process and also to detect faults during the printing process and correct such faults. For example, upon detection of the faults, an end effector  152  of robot  150  can remove the targeted portions and re-print the removed deposits of the splice portion  115 . According to another aspect of the present teachings, the controller  132  can log manufacturing data, such as position of the deposition, and process data such as voltage, amps, material flow rates, or other variables in association with the image data. 
     Additional information can be input directly into the controller  132  without measurement, such as a three-dimensional model of the splice portion  115  that will span the space between faces  108 ,  110 , a model of the cables  104 ,  106  or a model of the faces  108 ,  110 . The controller  132  can determine the three-dimensional structure of the splice portion  115  by extrapolating from the structure of one or both faces  108 ,  110 . The controller can determine through operation of an algorithm, or be supplied with, the structure of a splice portion  115  that will result in a longitudinally homogenous cable when added between faces  108 ,  110 . The cross-sectional structure in the splice portion  115  built up between faces  108 ,  110  will match that found in the remainder of the cables  104 ,  106 . Under circumstances where the faces  108 ,  110  have dissimilar cross-sectional structure, such as where one or more layers have a different size on one face  108 ,  110  relative to the other, the controller  132  can extrapolate a splice portion  115  that transitions between the two different cable sizes. In another aspect of the present teachings, the intermediate structure between dissimilar faces  108 ,  110  is provided to the controller  132 . Once information concerning the arrangement of the layers at faces  108 ,  110  is obtained, the controller  132  can operate the build heads  102  to incrementally print small amounts of material, gradually building up the splice portion  115  of cable between faces  108 ,  110 . 
     In addition to build heads  102 , a robot  150  can be implemented to apply a variety of materials and perform manufacturing steps in addition to the additive manufacturing performed, in part, by build heads  102 . An end effector  152  can apply tapes, wires or other materials, or can perform vapor deposition, or painting including electrostatic painting. According to another aspect of the present teachings, the end effector can perform cleaning steps including but not limited to application of solvents or other cleaning fluids. 
     With reference to  FIG. 2 , a cable splicing process  200  according to the present teachings can include step  202 , which includes cutting the cables  104 ,  106  at the ends  109 ,  111  of the cables, to form faces  108 ,  110 , which are, for example, flat and perpendicular to the direction of the cables  104 ,  106 . Such cuts can be made with mechanical cutting devices, and can be done after securing the cables  104 ,  106  to the securing members  126 ,  128 , or before. If the cutting is performed after securing cables  104 ,  106  to securing members  126 ,  128 , any adjustments to the rotational and axial position of the cables  104 ,  106  can be performed after cutting. In step  204 , both faces  108 ,  110  are cleaned with a suitable cleaner to remove any debris that for example can result from the cutting process performed in step  202 . This step can be performed by the machine  101  operator or automatically by the machine  101  itself. In step  206 , the ends  109 ,  111  are aligned relative to one another and locked into position with the securing members  126 ,  128 . Rotational alignment can be performed when the cables  104 ,  106  are not continuously rotationally symmetric, such as a Milliken conductor or trefoil conductor. For a Milliken cable, the rotational adjustment can be made to properly orient the wedge-shaped conductors, whereas in the trefoil cable the cable faces are properly oriented so that the three internal conductors are in the correct relative rotational position. 
     In step  208 , cover  113  is closed, forming the splicing chamber  112 . Splicing chamber  112  can allow for a controlled environment, such as when atmospheric air is purged from the chamber  112  and replaced with inert gas such as nitrogen or argon gas in order to provide a non-oxidizing environment for printing to take place. Other forms of controlled environments can involve filling the chamber  112  with non-inert gases, liquids or solid powders. 
     In step  210  the detection device  130  scans the faces  108 ,  110  of the cables  104 ,  106  to identify the various layers present in the cables  104 ,  106  and their positions. In step  212 , the controller  132 , based on the information gathered in step  210 , determines the composition and location of material to be printed in splice portion  115 , and the printing sequence resulting in each incremental deposit of material. In one aspect of the present teachings, each incremental deposit in the printing sequence can be represented by {i, M i , X i , Y i , Z i , P1 i , P2 i , . . . , Pk i }, where i is the index number ranging from 1 to N where N is the total number of incremental printing deposits made by machine  101 , M i  is the material for index i, X i , Y i , and Z i  are the coordinates for the ith deposit, and P1 i , P2 i , . . . , Pk i  are additional parameters such as a level of heat applied and time delay until the next deposit is made in the printing sequence. Such an approach can also be extrapolated to continuous printing by ensuring the increments are sufficiently numerous so as to approximate a continuous printing process. 
     In step  214 , the build heads  102  can print the layers of the splice portion  115  between faces  108 ,  110 . According to one aspect of the present teachings, the build heads  102  first print the conductor in the splice portion to completion, joining the conductor  114  in cable  104  and conductor  114  in cable  106 . This can be done by building up conducting material from the radial center of the conductor  114  at faces  108 ,  110 . As one non-limiting example, the print heads  102  print projections, for example conical mounds, from each face  108 ,  110  that join together in the region between faces  108 ,  110 . Once the printed conductors are first joined together, for example, when the first deposit is printed contiguous with the conductor built up from each of the faces  108 ,  110 , the remainder of the conductor  114  in the splice portion  115  can be built up radially to completion. Once the conductor  114  in the splice portion is complete, the machine  101  can print the next radially adjacent layers to completion, with each layer printed to completion prior to commencing printing of subsequent layers. Other printing sequences can be implemented, including ones incorporating faces  108 ,  110  having different starting shapes. According to one aspect of the present teachings, tapering faces  108 ,  110  such that each face is planar and has a normal projection angled upward, toward the build heads  102  relative to the longitudinal axis of the cables  104 ,  106  at the ends  109 ,  111 . In such a V-shaped configuration, the printing can be undertaken with the outer layers of the splice portion  115  distal to the print heads  102  printed first, with the remainder of the splice portion  115  built up toward the build heads rather than radially outward from the center of the faces  108 ,  110 . According to one aspect of the present teachings, the printing sequence is chosen so as to prevent inadvertent deposition of material or other disruption, such as overspray or inadvertent coating of exposed portions of the cables  104 ,  106 . The controller  132  can also detect with the detection device  130  in real-time whether such undesirable deposition or overspray occurs. In step  216 , after the outermost layer of the splice portion  115  has been completely printed, the cover  113  is opened and the ends  109 ,  111 , now part of a contiguous cable, are released from securing members  126 ,  128 . 
     In addition to splicing, additive manufacturing can be implemented to provide cable terminations. With reference to  FIG. 3 , system  300  for terminating a cable  304  includes single cable  304  secured within additive manufacturing machine  101 . Securing member  128  has been removed as it is not in use when printing cable termination  350 . The cable  304  includes layers similar to cable  104  and is secured to securing member  126  at cable end  309 . Face  308  is cut and cleaned similarly to face  108 . The machine  101  can then print a termination  350  on the secured end  309  of cable  304 . The three-dimensional structure of the termination  350  can be input into controller  132 , which can then convert such information into a printing sequence that includes the order of the incremental deposits of material, the selection of the material and the location of the incremental deposits during the printing sequence. According to another aspect of the present teachings, the sequence required to print the termination  350  is directly input into the controller  132 . According to still another aspect of the present teachings, control of the printing sequence can be done manually. 
     With continued reference to  FIG. 3 , the additive manufacturing machine  101  can build aspects of a termination  350  for the cable  304  such as collar  360 , pressure ring  362 , stress cone  364  and insulator  366 . It should be noted that other forms of stress control, insulation, and other structures can be printed to form a custom cable termination  350 . The termination  350  can be printed on the cable face  308  and cable end  309 . When the process of printing the termination  350  is complete, the termination  350  is structurally and electrically a copy of a standard cable termination. It should be noted that additional features of a complete termination can be added after completion of the printing process, such as clamps, connectors, and including aspects that could otherwise be printed such as insulation  366 . Such features can be applied, for example, by end effector  152  of robot  150 . After completion, the cover  113  opens and the machine can release the cable  304  from securing member  126 . 
     With reference to  FIG. 4 , an additive manufacturing cable termination process  400  according to the present teachings can include step  402 , which includes cutting the end  309  of the cable  304 , thereby forming a face  308  upon which the termination  350  will be printed. In step  404 , the end  308  is cleaned with a suitable cleaner. In step  406 , the end  309  can be positioned and secured with the securing member  126 . In step  408 , cover  113  is closed, forming the printing chamber  112 . A controlled environment is provided within chamber  112 , for example by purging atmospheric air and replacing with non-oxidizing inert gas such as nitrogen or argon gas. In step  410  the detection device  130  scans the face  108  of the cable  104  to identify the various layers present in the cable  104  and their positions. In step  412 , the controller  132 , based on the information gathered in step  410 , determines the composition and location of material to be printed in termination  350 , and the printing sequence resulting in each incremental deposit of material. In step  414 , the build heads  102  can print the termination  350  on face  108  and surrounding cable end  309 . According to one aspect of the present teachings, the build heads  102  first print the stress cone  364 , and then the insulation  366 , followed by the collar  360  and pressure ring  362 . In step  416 , after the termination  350  has been completely printed, the cover  113  is opened and the end  309  including the printed termination  350  is released from securing member  126 . 
     In the present disclosure, reference numerals followed by alphabetic indices refer to one of the illustrated elements, while use of the reference numeral without the alphabetic indices refer to one or more of the illustrated elements. For the purposes of this disclosure and unless otherwise specified, “a” or “an” means “one or more.” To the extent that the term “includes” or “including” is used in the specification or the claims, it is intended to be inclusive in a manner similar to the term “comprising” as that term is interpreted when employed as a transitional word in a claim. Furthermore, to the extent that the term “or” is employed (e.g., A or B) it is intended to mean “A or B or both.” When the applicants intend to indicate “only A or B but not both” then the term “only A or B but not both” will be employed. As used herein, “about” will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, “about” will mean up to plus or minus 10% of the particular term. From about A to B is intended to mean from about A to about B, where A and B are the specified values. 
     The description of various embodiments and the details of those embodiments is illustrative and is not intended to restrict or in any way limit the scope of the claimed invention to those embodiments and details. Additional advantages and modifications will be apparent to those skilled in the art. Therefore, the invention, in its broader aspects, is not limited to the specific details and illustrative examples shown and described. Accordingly, departures may be made from such details without departing from the spirit or scope of the applicant&#39;s claimed invention.