System for automated winding of coils

Abstract

The present disclosure relates to system for automated fabrication of coils (312) The system comprises a rotating mandrel (10), configured to rotate about an axis of rotation and to receive a plurality of turns (33) and a plurality of layers (34) of a wire (31). The system further comprises a wire feeding assembly (40) configured to guide and feed the wire (31) to the rotating mandrel (10). The system also comprises a movable support (20) configured to hold the wire feeding assembly (40) and to move the wire feeding assembly (40) with at least two degrees of freedom substantially in a plane perpendicular to the axis of rotation of the rotating mandrel (10). The present disclosure also relates to methods (400) for manufacturing a coil (312) with a system for automated fabrication of coils (312).

Description

SYSTEM FOR AUTOMATED WINDING OF COILS

[0001] The present disclosure relates to precision coils and, more particularly, to systems for automatic fabrication of precision coils.BACKGROUND

[0002] High intensity magnetic fields are required in a number of applications, such as those involving electrical machines or high intensity magnets. High intensity magnetic fields may be achieved by using superconducting coils which comprise a plurality of turns of a superconducting wire wound in multiple layers around a core or mandrel.

[0003] The manufacture of superconducting coils is subject to especially high precision requirements. Stringent electromagnetic, thermal and mechanical demands require superconducting coils to be free of defects such as gaps, crossovers, loose wires or any other anomaly. Coils should be formed with densely packed wires, which requires precise control of both layer-to-layer and turn-to-turn transitions during the winding process. Thus, it is desirable to arrange the exact number of turns and the exact number of layers into the available space of a winding bobbin or mandrel. Any deviation of wire placement may accumulate during the winding process and result in a wrong number of turns or layers in the coil. Apart from precise control of the position of the wire, constant tension should also be maintained during the winding process to avoid any looseness in the manufactured coil.

[0004] Both position and tension control become especially challenging when manufacturing non-round coils. Other geometries, such as racetrack-shaped coils, may be required in certain applications.

[0005] Quality requirements may become even more difficult to fulfill when using wetwound coils, i.e. coils whose windings are covered or supported with a glue-type (e.g. epoxy) material. In this case, a further requirement is concerned with achieving a consistent and uniform distribution of the glue-type agent over the surface of the windings. Furthermore, the use of a glue-type material may lead to some slippage of the wire during the winding process and the wire may drift off position, thus hindering the process.

[0006] Some existing methods for manufacturing coils involve a significant amount of manual manipulation. This is labor intensive, which results in a high cost and potential safety concerns for the operators. Besides, limited production rates are typically obtained with such processes. Furthermore, manual manipulation is susceptible to human errors, so that uniformity and consistency among manufactured coils is difficult to obtain and significant coil variability is observed. This is especially the case for wet-wound coils. Automatic systems for producing precision coils have been already proposed as shown in, e.g. US9201128B2.

[0007] Still, improved systems and methods for the automatic manufacturing of coils, especially comprising superconducting wires, are desired to enable high production rates and high quality. The present disclosure seeks to provide systems and methods to address at least one of the above-mentioned aspects.

[0008] Examples of the solutions presented in this disclosure may be particularly suitable for application in wind turbines, which are used to supply electricity into the electrical grid. Wind turbines generally comprise a tower and a rotor arranged on the tower. The rotor, which typically comprises a hub and a plurality of blades, is set into rotation under the influence of the wind on the blades. Said rotation generates a moment that is normally transmitted to a generator.

[0009] The generator may be a superconducting generator. The superconducting generator may have a magnetic field generator and an armature, the magnetic field generator being configured to generate a magnetic field and the armature being configured to support a voltage induced in its windings due to the time-varying magnetic field created by the relative motion of the armature and the magnetic field generator.

[0010] The magnetic field generator may comprise coils of superconducting windings including electrically conductive materials, i.e. conductors, that transition to a superconducting state at a sufficiently low temperature. Thus, the superconducting windings may support very high current densities without incurring any dissipation and thus generate very high magnetic fields. Therefore, same or more power may be obtained with a superconducting generator with respect to a conventional non-superconducting generator, the superconducting generator being smaller in size and weight than the conventional generator. Consequently, a more efficient design of the wind turbine may be enabled.

[0011] High precision coils according to the present disclosure may be employed in such wind turbine generators. Nevertheless, a person skilled in the art will recognize that the scope of the present disclosure is not limited to such applications. Thus, systems and methods presented in this disclosure may also be applicable in any other applications requiring highintensity magnetic fields obtained by means of high precision coils. These may include the use of superconducting electrical coils in magnetic resonance imaging (MRI), or the use of superconducting electrical coils in motors for fully-electric aircrafts or ships.

[0012] Throughout this disclosure, the terms conductor or wire may be used interchangeably to refer to the cable or wire of electrically conductive material that is wound to form a coil. Wires may be of multiple shapes (e.g. round, rectangular) within the frame of the present disclosure and they may be formed of different conducting materials (e.g. aluminum, copper or superconducting materials).

[0013] As indicated, wet-wound coils comprise a glue-type compound or substance to coat the wire. Different glue-type substances (e.g. epoxy resin, paraffin) may be used. Throughout this disclosure, the terms glue and coating may be used interchangeably to refer to the substance used to coat the wires in wet-wound coils.SUMMARY

[0014] In an aspect of the present disclosure, a system for automated fabrication of coils is provided. The system comprises a rotating mandrel, configured to rotate about an axis of rotation and to receive a plurality of turns and a plurality of layers of a wire. The system further comprises a wire feeding assembly configured to guide and feed the wire to the rotating mandrel. The system also comprises a movable support configured to hold the wire feeding assembly and to move the wire feeding assembly with at least two degrees of freedom substantially in a plane perpendicular to the axis of rotation of the mandrel.

[0015] According to this aspect of the disclosure, a system is disclosed by which a wire is deposited on the mandrel in a highly controlled manner. It should be indicated that the wire may be fed directly on the surface of the mandrel at the beginning of the process. As will be apparent to any person skilled in the art, the same system may equally feed the wire on a previously formed layer of the coil being manufactured in the usual case of coils comprising multiple layers. In particular, the wire feeding assembly is configured to ensure a proper preparation of the wire before feeding it to the rotating mandrel. Furthermore, the use of a movable support for the wire feeding assembly, with a capability to move the wire feeding assembly with at least two degrees of freedom, allows for a precise control of the relative position between the feeding assembly and the point of contact of the wire with the mandrel (or with a previously formed layer of the coil).

[0016] The control of the relative position of the wire feeding assembly with respect to the mandrel may be particularly relevant in case of non-circular mandrels and, consequently, non-circular coils. By adjusting the position of the wire feeding assembly with the movable support, the relative orientation and / or the distance between the wire feeding assembly and the point of contact of the mandrel may be advantageously controlled even when using mandrels of varying shapes, such as a racetrack shape.

[0017] The accurate control of the relative position provides for an improved control of the winding process, which results in an easier automation, thus avoiding manual operations by an operator. As a result, a more efficient process requiring less time and producing coils with less defects may be obtained.

[0018] In a further aspect of the disclosure, a method for manufacturing a coil with a system according to the previous aspect is also provided. The method comprises fixing an end of a wire at a lead-in point on a surface of the rotating mandrel. The method also comprises starting rotation of the rotating mandrel while feeding the wire with the wire feeding assembly, so that the wire is wound on the rotating mandrel. The relative position between the wire feeding assembly and the point of contact of the wire with the rotating mandrel or with a previously formed layers of the coil is monitored. Finally, the method comprises adjusting the position of the wire feeding assembly by moving the movable support holding the wire feeding assembly so as to ensure the wire is fed in a substantially horizontal orientation.

[0019] A lead-in point is to be understood as a starting point for the manufacture of the coil. The precise location of the lead-in point may depend on different aspects such as the shape of the coil and / or the integration of the coil in its final application system.

[0020] Only for clarification purposes, it should be mentioned that the wire is directly fed on the surface of the rotating mandrel only at the beginning of the coil manufacturing process until a first layer of the coil is completed. Afterwards, the same process may be followed but the wire is no longer fed directly to the surface of the rotating mandrel but to the surface of a previously formed layer of the coil being manufactured.

[0021] According to this another aspect of the disclosure, a robust and reliable method is provided for the manufacture of a precision coil. Thus, the adjustment of the relative position between the wire feeding assembly and the point of contact of the wire with the mandrel allows for a real-time control of the winding process.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 provides a schematic view of a coil according to an example;

[0023] Figure 2 illustrates a perspective view of one example of a wind turbine;

[0024] Figure 3 illustrates a simplified, internal view of one example of the nacelle of the wind turbine of figure 2;

[0025] Figure 4 schematically illustrates one example of a system for winding a coil according to the disclosure;

[0026] Figure 5 schematically illustrates a portion, comprising a mandrel, of an example of a system for winding a coil according to the disclosure;

[0027] Figure 6 schematically illustrates a portion, comprising a moving support for a wire feeding assembly, of an example of a system for winding a coil according to the disclosure;

[0028] Figure 7 schematically illustrates the relative position between a rotating mandrel and a wire feeding assembly during a turn of the mandrel according to an example;

[0029] Figure 8 schematically shows a tension control sytem for the wire according to an example;

[0030] Figure 9 provides a schematic perspective view of a wire feeding system according to an example;

[0031] Figure 10 schematically represents the arrangement of multiple turns of the wire in a coil according to an example;

[0032] Figure 11 schematically illustrates operation of a turn-to-turn bending system according to an example;

[0033] Figure 12 provides a schematic perspective view of an example of a coating dispensing system;

[0034] Figure 13 provides an overview of a system for winding a coil including a monitoring and a control unit according to an example;

[0035] Figure 14 shows a flowchart of an example of a method for manufacturing a coil.DETAILED DESCRIPTION OF EXAMPLES

[0036] Reference now will be made in detail to examples, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation only, not as a limitation. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present disclosure. For instance, features illustrated or described as part of one example can be used with another example to yield a still further example. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

[0037] Figure 1 is a schematic view of an example of a coil 312 according to the disclosure. The coil 312 is wound around a mandrel 10 and it comprises a plurality of turns 33 and a plurality of layers 34. Although a coil 312 comprising six turns 33 and four layers 34 is represented in Figure 1 , it should be understood that this is only for illustrative purposes. Thus, the number of turns and layers may be adjusted depending on the requirements of the specific application. In some examples, the number of turns per layer may be in the range of 20 to 50, whereas the number of layers may be in the range from 50 to 150.

[0038] The shape and size of the coil 312 may depend on the geometry of the mandrel 10 used for the winding process. In an example, a circular mandrel may be used, thus producing a round coil (i.e. a cylindrical coil with a round cross-section). In other examples, a racetrack shaped mandrel may be employed, in which case a racetrack coil may also be fabricated. As with the number of turns and layers, the shape of the coil 312 may also be dependent on the intended application for the coil.

[0039] As for the characteristics of the wire 31 of the windings, different geometries may be selected. In examples of the disclosure, a round wire may be used. In other examples, a square or rectangular cross-section may be defined for the wire 31. Furthermore, the dimensions of the wire 31 may also be dependent on the application. In the example shown in Figure 1 , a rectangular wire 31 is shown. Nevertheless, the present disclosure is in no way limited by the geometry of the conductor which may be adapted to the needs of the required application. Similarly, different materials may be used for the wire 31. In some examples, a superconducting material may be selected.

[0040] In precision coil winding, turns 33 of each layer 34 may be disposed directly on top of already closed turns 33 of the preceding layers 34, i.e. the turns 33 may be aligned with the turns 33 of a previously formed layer 34. Alternatively, turns 33 may be disposed in valleys formed between already closed turns 33. The selection of one option or the other may depend on, e.g. the cross-section of the wire 31. On the one hand, examples comprising deposition of turns 33 of a layer directly on top of turns 33 of a previously formed layer may be preferred in case of square and / or rectangular wires 31. On the other hand, arrangement of turns 33 in the valleys of previously deposited turns 33 may be preferred when dealing with wires 31 with a circular cross-section as this may allow for a more compact packaging in this case.

[0041] Both dry-wound coils and wet-wound coils may be provided in examples of the disclosure. In examples comprising wet-wound coils, a coating material in the form of a layer of a glue-type agent (e.g. epoxy resin, paraffin) may be used to encapsulate the conductor or wire 31. In this manner, thermal and mechanical stability of the coil 312 may be improved. In the example of the coil 312 depicted in Figure 1 , such a glue-type agent is indeed present asindicated by numeral 32 which is completely surrounding the wire 31. In an example, the coating material may include an epoxy based resin. In other examples, the coating glue-type material may include a non-epoxy resin. In examples comprising dry-wound coils, no such glue-type material may be used to encapsulate the wire 31 .

[0042] As previously mentioned, coils 312 according to the present disclosure may be used in a large number of applications. Among them, coils 312 may be used in electrical machines and, more particularly, they may be used in electrical generators for wind turbines. In some specific examples, the coils used for electrical generators of wind turbines may comprise superconducting materials for the wires 31 .

[0043] Figure 2 illustrates a perspective view of one example of a wind turbine 100 which may include a generator 300 comprising coils according to the present disclosure. It should be appreciated that the generator 300 may be either a superconducting generator having at least one superconducting winding or a conventional (e.g., non-superconducting) generator. It should further be appreciated that the utilization of the generator 300 in the wind turbine 100 is offered by way of a nonlimiting example of an application of a coil 312.

[0044] As shown in Figure 2, the wind turbine 100 includes a tower 102 extending from a support surface 104, a nacelle 106 mounted on the tower 102, and a rotor 108 coupled to the nacelle 106. The rotor 108 may include a rotatable hub 110 and at least one rotor blade 112 coupled to, and extending outwardly from, the hub 110. For example, in the illustrated example, the rotor 108 includes three rotor blades 112. However, in an additional example, the rotor 108 may include more or less than three rotor blades 112. Each rotor blade 112 may be spaced about the hub 110 to facilitate rotating the rotor 108 to enable kinetic energy to be transferred from the wind into usable mechanical energy, and subsequently, electrical energy. For instance, the hub 110 may be rotatably coupled to the electrical generator 300 to permit electrical energy to be produced.

[0046] Referring now to Figure 3, a simplified, internal view of one example of the nacelle 106 including a superconducting generator 300 is illustrated. As shown, the generator 300 may be coupled to the hub 110 for producing electrical power from the rotational energy generated by the rotor 108. In this example, a support tube 114 is connected directly to the hub 110 and supports the rotatable component 302 (including at least one armature winding assembly 304 and yoke or body 306). Thus, the rotatable component 302 may be configured to rotate in response to the rotational energy generated by the rotor 108.

[0047] In an example, the rotatable component 302 may be arranged to be coaxial with a non- rotatable component 308 about axis (A). Accordingly, the rotatable component 302 and thenon-rotatable component 308 may be coaxial with the rotor 108. In an example, the armature winding assembly 304 may be configured to rotate with the rotatable component 302 about the axis (A) and about a field winding assembly 310 supported by the non-rotatable component 308.

[0048] As depicted in Figure 2, in an example wherein the generator 300 is configured as a superconducting generator, the field winding assembly 310 may be a superconducting field winding assembly 310. Accordingly, the field winding assembly 310 may include superconducting coils 312, which may be a group of coils formed in a racetrack shape.

[0049] In an example, the superconducting coils 312 may be constrained to retain the racetrack shape, such as by a structure of the non-rotatable component 308. As such, each superconducting coil 312 may be supported in a cooling recess / passage 314 of the non- rotatable component 308. Each cooling recess / passage 314 may facilitate cooling each superconducting coil 312, via a bath of helium, to cryogenic temperatures or by other known methods within the engineering field of cryogenics.

[0050] The superconducting coils 312 may, in an example, be arranged side-by-side in an annular array extending around the non-rotatable component 308. For example, thirty-six (36) coils 312 may form an annular array of field windings that serve as the stator field winding for the generator 300. In an example, the superconducting coils 312 may be each formed of (NbTi or other superconducting) wire wrapped around a racetrack form that may include cooling conduits for the helium. The superconducting field winding assembly may include superconducting coil magnets 316, which are enclosed in the non-rotatable component 308 and receive cryogen through cooling recesses / passages 314.

[0052] As further depicted in Figure 3, cryogen re-condensers 116, 118 may be housed in the nacelle 106, provided that the cryogen cooling liquid in the re-condensers is at least partially elevated aboye the superconducting field windings to provide for gravity feed of the cryogen to the field winding assembly 310. Alternatively, the cryogen re-condensers 116, 118 may be mounted on top of the nacelle.

[0044] Figure 4 provides a schematic view of a system for automated fabrication of coils according to an example. The system comprises a mandrel 10 and a spindle (not visible in Figure 4) configured to rotate the mandrel 10. The rotating mandrel 10 in this example may be substantially racetrack shaped, which implies that the manufactured coils 312 will also have a racetrack shape. By selecting a different geometry for the mandrel 10, e.g., circular, coils 312 of different geometries may be equally obtained.

[0045] Also shown in Figure 4 is the wire feeding assembly 40, which is configured to guide and feed a wire 31 of a conductor material to the mandrel 10. Finally, a movable support 20 is also depicted.

[0046] In order to manufacture a coil 312, a first end of the wire 31 may be attached at one starting point (or lead-in point) in the surface of the mandrel. In an example of the disclosure, the starting point may be arranged at one axial end of the coil 312. Subsequently, the mandrel 10 may be rotated as the wire 31 is fed from the wire feeding assembly 40 so that it is wound on the mandrel 10. A complete rotation of the mandrel 10 may then correspond to a loop or turn 33 of the manufactured coil 312. High accuracy in the relative positioning of the wire 31 with respect to the mandrel 10 may be required during the winding process in order to obtain a compact and dense coil as the one schematically depicted in Figure 1 . To this end, a precise positioning of the wire feeding assembly 40 with respect to the mandrel 10 may be achieved by means of the movable support 20 as will be explained in more detail below.

[0047] Figure 5 shows a perspective view of the mandrel system. The mandrel 10 is fixed on a spindle and a motor 13 is arranged to rotate the mandrel 10. The rotational speed of the mandrel 10 may be adjusted by properly controlling the motor 13. In an example, a spindle may be arranged to rotate the mandrel 10, the spindle being configured to adjust the rotational speed of the rotating mandrel 10 relative to the angular position of the mandrel 10. Consequently, the rotational speed of the mandrel 10 may be adjusted within a single rotation. This example may be specifically used when employing non-circular mandrels, e.g. racetrack shaped mandrels. Thus, by dynamically adjusting the rotational speed of the mandrel 10 as a function of its angular position, one may adjust both the speed and the tension of the wire 31 so as to keep them substantially constant and within certain limit values. In examples of the disclosure, the rotational speed of the mandrel 10 may be in the range of 5 to 10 rpms.

[0048] Maintaining a substantially constant speed for the wire 31 and a substantially constant tension may be desirable as significant variations in tension may induce several risks. Some of those risks may include breakage of the wire 31 if the tension is too high and it exceeds the yield strength of the material of the wire 31 . On the contrary, if not enough tension is present, a loose winding may be obtained or the wire 31 may simply scape the guiding system.

[0049] From a constructive point of view, the mandrel 10 may be split into multiple pieces. The pieces may be adjustable and demountable and different materials, such as aluminum or stainless steel, may be used for their manufacture. Furthermore, the mandrel 10 may be coated with polytetrafluoroethylene (PTFE) to improve its functional properties.

[0050] Furthermore, a monitoring system may be provided. As an example, a profilometer 12 is shown in Figure 5. A profilometer 12 may be attached to the mandrel 10 and it may be configured to monitor the status of the wire 31 deposited on the mandrel 10 so as to ensure a proper orientation and pitch of the different turns 33. The profilometer 12 may facilitate detection of anomalous wire profiles that may anticipate the presence of one or more winding defects in the coil 312. More specifically, a profilometer 12 may measure the shape of the forming coil 312 in the course of the winding as well as the right positioning of the wire 31 to prevent defects like layer jumps, twisting, overlays, gaps, etc.

[0051] Oher than a profilometer 12, the system may comprise a camera or other sensors (not shown in the figure) for profiling the forming coil 312 during the winding process. The camera, profilometer 12 and other sensors may be configured to provide real-time measurements of the profile of the coil 312, wire 31 feed rate, mandrel 10 rotational speed or combinations thereof. The profilometer 12 may also be used to ensure that, when using nonround wires, e.g. rectangular wires like the one depicted in Figure 1 , the positioning of the wire 31 is correct.

[0052] The mandrel 10 may also comprise at least one mandrel indexation feature 15. This mandrel indexation feature 15 may be used to accurately determine the exact position of the mandrel 10. This may be used to, e.g. determine the angular position of the mandrel 10 and / or to accurately determine the plane of rotation of the mandrel 10. The plane of rotation of the mandrel 10 may be corrected to ensure that it is substantially parallel to the motion plane of the wire feeding assembly 40 during one turn or loop. In order to adjust the plane of rotation of the mandrel 10, an adjustable table or frame may be used to support the mandrel 10.

[0053] Figure 6 provides a more detailed view of the movable support 20 which holds and moves the wire feeding assembly 40. The movable support 20 is configured to move the wire feeding assembly 40 with at least two degrees of freedom. In examples of the disclosure, the at least two degrees of freedom may comprise two perpendicular directions. Hence, in an example of the disclosure, the movable support 20 may be configured to move the wire feeding assembly 40 in three perpendicular directions, more specifically, in a horizonal (X) and a vertical (Z) direction in a plane perpendicular to the axis of rotation of the rotating mandrel (10) and in axial (Y) direction parallel to the axis of rotation of the rotating mandrel 10.

[0054] To this end, the wire feeding assembly 40, which is only schematically represented in Figure 6, may be attached to an axial arm 23 in such a manner that it may be displaced along the axial arm 23, i.e., along the axial direction, Y. The axial arm 23 may be mounted on a vertical arm 22. The axial arm 23 may be configured to move along the vertical arm 22, i.e., to move along the vertical direction, Z. Finally, the vertical arm 22 may be on its part mountedon a horizontal arm 21 and it may be further configured to move along said horizontal arm 21 , i.e., along the X direction. In other words, the movable support 20 may comprise a horizontal arm 21 , a vertical arm 22 and an axial arm 23 for movement of the wire feeding assembly 40 in the horizontal (X), vertical (Z) and axial (Y) direction respectively. The vertical arm 22 may be installed on the horizontal arm 21 and the axial arm 23 may be installed on the vertical arm 22.

[0055] As will be apparent to those skilled in the art, alternative examples may be provided which may also facilitate the movement of the wire feeding assembly 40 along the three directions. Thus, in a further non-limiting example, the movable support 20 may comprise a horizontal arm 21 for movement of the wire feeding assembly 40 in the horizonal (X) direction, a vertical arm 22 for movement of the wire feeding assembly 40 in the vertical (Z) direction and an axial arm 23 for movement of the wire feeding assembly 40 in the axial (Y) direction. In this further example, the horizontal arm 21 may be installed on the vertical arm 22 (as opposed to the previous example) and the axial arm 23 may be installed on the horizontal arm 21 (and not on the vertical arm 22 as in the previous example). With this alternative example, the same degrees of freedom may be achieved for the movement of the wire feeding assembly 40.

[0056] Movement along the axis Y may be used to effectively define the axial position of the different turns 33 of the coil 312 which, as explained with reference to Figure 1 , may be arranged side by side with a certain pitch in between turns. A very precise positioning of the wire 31 along the Y (i.e., axial) direction may be required.

[0057] A controller may be provided in an example to monitor the relative position between the wire feeding assembly 40 and the point of contact of the wire 31 with the rotating mandrel 10 (or with an already formed layer of the coil). The controller may be configured to adjust the position of the movable support 20 so as to ensure a horizontal and tangential direction of the wire 31 during winding.

[0058] As shown in Figure 7, movement in the vertical (Z) direction may be provided in examples of the disclosure. In this manner, a substantially horizontal orientation of the wire 31 may be provided during the winding process. Keeping the wire 31 in a horizontal orientation may allow consistent application of the epoxy resin or other glue compound used as a coating material when fabricating wet-wound coils. More specifically, the horizontal orientation may avoid any change arising from gravity why may otherwise have an effect on the distribution of the substantially liquid coating material (e.g. glue type agent such as epoxy resin or paraffin) on the wire 31. The movable support 20 may displace the wire feeding assembly 40 in the vertical direction (Z). This may be specifically applicable to coils exhibiting non-round shapes such as the racetrack shape depicted in Figure 7. In this example, the point of contact of thewire 31 and the mandrel 10 may move in the vertical direction as the mandrel 10 rotates due to non-circular geometry of the mandrel 10.

[0059] In order to ensure a horizontal orientation of the wire 31 , i.e., to ensure that the wire is fed in a tangentially horizontal manner, the control of the movable support 20 holding the wire feeding assembly 40 may be coupled to the angular position of the mandrel 10.

[0060] As also shown in Figure 7, the movable support 20 may also displace the wire feeding assembly 40 in the horizontal direction (X) over the course of a rotation of the mandrel 10. Thus, during the manufacture of a turn 33 of the coil 312, i.e. during a single rotation of the mandrel 10, the control of the movable support 20 may be coupled to the angular position of the mandrel 10, not only to adjust the vertical position of the wire feeding assembly 40, but also its horizontal displacement, i.e. its displacement in the X direction. In this manner, a substantially constant distance between the wire feeding assembly 40 and the point of contact of the wire 31 at the mandrel 10 may be ensured. This may be particularly relevant for the manufacture of wet-wound coils, as ensuring a constant and minimum distance may facilitate a uniform coating of the wire 31 upon its deposition on the mandrel 10 or on a previously formed layer 34 of the manufactured coil 312.

[0061] Consistent tension during coil winding is required to manufacture precision coils without defects. For a round coil, tension may not vary significantly during one revolution because the point of contact of the wire 31 and the mandrel 10 remains substantially fixed. Nevertheless, tension may be subjected to significant variations when other geometries (rectangular, racetrack, etc.) are employed, due to changing wire paths between the wire feeding assembly 40 and the mandrel 10.

[0062] Rotational speed of the mandrel 10 may be controlled to help maintain a substantially constant tension. Nevertheless, in order to further control the tension of the wire 31 , a tension control system 50 may be arranged to maintain a controllable tension on the wire 31 during the winding process. Passive and / or active tension control devices may be used. A system comprising pulleys, wheels and a dancer (with preloaded spring) may be used to control the tension as known in the art. Such a tension control system 50 is depicted in Figure 8. Figure 8 shows the supply source bobbin 51 . The wire 31 is passed via a number of wheels and pulleys 52, including a dancer, until it reaches the wire feeding assembly 40, which is held on the movable support 20 before being fed to the mandrel 10.

[0063] Both open-loop and closed-loop tension control systems may be implemented in examples of the disclosure. In an open loop tension control sytem, no actual tension feedback may be provided so that the control may simply be based on a tension setpoint with nofeedback. Accordingly, open-loop tension control systems may not respond to tension disturbances during the winding process. Closed-loop control may incorporate a tension sensor and an active dancer system to control the tension of the wire 31 during the winding process.

[0064] Figure 9 provides a perspective schematic view of a wire feeding assembly 40 according to an example of the disclosure. As shown in the figure, the wire feeding assembly 40 comprises a support 41 which may be used to support different sub-systems. Thus, the wire feeding assembly 40 may comprise a coating dispensing system 80 configured to coat at least a portion of the surface of the wire 31 before the wire 31 is fed to the rotating mandrel 10. In addition, the wire feeding assembly 40 may comprise a wire axial bending system 60 configured to bend the wire 31 in a substantially horizontal direction before the wire 31 is fed to the rotating mandrel 10. Furthermore, the wire feeding assembly 40 may comprise a wire vertical bending system 70 configured to bend the wire 31 in a substantially vertical direction before the wire 31 is fed to the rotating mandrel 10. The function of each of those subsystems will be addressed below. In examples of the disclosure, only one or two of the mentioned systems may be arranged in the wire feeding assembly 40. Thus, by way of a non-limiting example, no coating dispensing system 80 may be used in a system intended for fabrication of dry-wound coils.

[0065] In an example of the disclosure, the winding system may be configured to dispose the wire 31 in a non-helical fashion when manufacturing a coil 312. More specifically, a so- called circular form may be used in which a plurality of loops (i.e. turns 33) may be disposed on the mandrel 10. Each rotation of the spindle may generate a loop or turn 33 lying in a plane substantially parallel to the plane of rotation of the mandrel 10. The coil 312 may comprise multiple layers 34 (as shown in Figure 1) with each layer 34 comprising a plurality of turns 33. Each turn 33 may comprise a so-called parallel region and a transition region.

[0066] The parallel region may substantially adopt the shape of the mandrel 10. Thus, a circular parallel region may result from a circular mandrel whereas a racetrack shaped parallel region may result from a mandrel 10 with a racetrack geometry. Figure 10 schematically depicts a portion of a forming coil 312 comprising multiple turns 33. As shown in the figure, each turn 33 may comprise a loop or parallel portion 33a, 33b that remains substantially parallel to the plane of the mandrel 10 and a transition region 33c.

[0067] The transition region 33c may be defined as a region where turns 33 of the wire 31 cross-over from one axial position to the next position. In other words, the transition region 33c may be defined as the ending regions for a certain turn 33 and the starting regions for the adjacent turn 33. During cross-over, the wire 31 may advance axially by a certain predefinedamount. More specifically, the magnitude of the axial shift in the transition regions 33c may substantially correspond to the sum of the width of the wire 31 and the desired pitch 36 between turns 33.

[0068] To maximize winding density and promote mechanical stability of the coil 312, it may be desired that the transition from one turn 33 to the next occurs over a short wire length, i.e. the transition region 33c may be kept as short as possible in examples of the disclosure. Thus, as a non-limiting example, the loop or parallel portion 33a, 33b of the turns may extend for 350-355° of the overall rotation whereas the transition region 33c may span over the remaining 5-10°. In order to facilitate such short transition region 33c, in some examples of the disclosure a pre-bent of the wire 31 may be carried out on top of the simple displacement of the wire feeding assembly 40 in the axial direction. Such pre-bending of the wire 31 may be achieved with a bending system 60, which may be arranged in the wire feeding assembly 40 as shown in Figure 9.

[0069] In order to pre-bend the wire 31 , the turn-to-turn axial bending system 60 may comprise at least a pair of fingers configured to engage with the wire 31 so as to twist the wire 31 and induce a pre-bend of the wire 31 in a horizontal direction, the horizontal direction being an axial direction (Y) substantially parallel to the rotation axis of the mandrel 10. In the example depicted in Figure 9, two pairs of fingers 61a-61 b and 62a-62b are shown. Thus, the wire 31 may be guided to pass in between the two fingers of one of the pairs. By displacing the fingers with respect to each other, the wire 31 may be twisted, thus resulting in a pre-bent. By properly selecting the size of the fingers 61a-61 b, 62a-62b and the magnitude of the displacement, the amount of the twisting may be adjusted. One pair of fingers 61 a, 61b or the other 62a, 62b may be used depending on the direction (+Y or -Y) of the intended horizontal displacement.

[0070] Figure 11 shows a simplified view of the operation of the turn-to-turn axial bending system 60. The above figure shows the wire 31 as it passes between the two fingers 62a-62b of a pair of fingers. The figure below shows the result after actuation of the fingers 62a-62b Thus, by displacing at least one of the fingers in the axial direction, a twisting is carried out and a pre-bend is induced in the wire 31. The pre-bend defines an S-turn shape and the magnitude of the pre-bend may be equal to the axial displacement needed in the transition region 33c. In other words, the magnitude of the bend may be such that the distance, dtUm, between the wire 31 before and after the bending process corresponds to the width of the wire 31 plus the pitch 36 between turns 33.

[0071] Figure 10 shows a number of turns 33 of a certain layer of the coil 312 and a first turn 35 of a subsequent layer. Thus, as also shown in Figure 1 , not only turn-to-turn, but also layer-to-layer transition may be accurately controlled. Thus, in a further example, the wire 31may also be pre-bent in the vertical direction when starting a new layer 34. A precision layer- to-layer transition may then be achieved by defining a step in the vertical direction, thus ensuring a smooth transition. To this end, a layer-to-layer bending system 70 may also be included in the wire feeding assembly 40 as shown in Figure 9. The layer-to-layer bending sytem 70 may comprise an upper and a lower jack clamps 71 , 72, the jack clamps 71 , 72 being configured to bend the wire 31 in the vertical direction so as to induce a vertical pre-bend of the wire 31. The magnitude of the pre-bend may be dimensioned to provide a proper gap below the wire 31 of the next layer. In particular, the step defined by the pre-bending process may be based on the thickness ofthe wire 31 and on the thickness of the coating material 32 (if present) disposed in between consecutive layers 34.

[0072] The system according to the disclosure may be configured to manufacture either dry-wound coils or wet-wound coils. In the latter case, at least a portion of the wire 31 may be coated with a coating material 32. The coating material may be a glue-type substance such as an epoxy resin or paraffin. Wet-wound coils may be especially difficult to manufacture. The nominal target values for the thickness of the coating material may be in the range of 20 to 80 micron for the inter-turn and inter-layer spacings.

[0073] In an example of the disclosure, the wire 31 may be coated with a glue-type agent along the path to the mandrel 10, i.e. prior to the wire 31 being disposed on the mandrel 10, as opposed to the wire 31 being coated after winding. In particular, the at least section of the wire 31 to be coated, may be coated immediately prior to the placement of the wire 31 on the mandrel 10. In this manner, a more uniform and controllable distribution of the coating material (e.g. epoxy resin, paraffin) on the wire 31 surface may be obtained. To this end, the wire feeding assembly 40 may comprise an automatic coating dispensing system or needle 80 as also shown in Figure 9. In some examples of the disclosure, the coating dispensing system 80 may be arranged such that the wire 31 may be coated before being pre-bent by either the layer-to-layer bending system 70 or the turn-to-turn bending system 60. In other examples, the coating dispensing system 80 may be disposed after the pre-bending systems 60, 70.

[0074] The coating dispensing system 80 may be configured to dispose a desirable amount of coating material on at least a portion of the wire 31 but not over all the surfaces of the wire 31 . In an example comprising a wire 31 with a rectangular cross-section, glue may be applied only on three sides (e.g. bottom and lateral sides) ofthe wire 31 . In this manner, a more uniform thickness of glue surrounding the wire 31 may be obtained.

[0075] Figure 12 provides a perspective schematic view of a coating dispensing system 80 according to an example. The coating dispensing system or needle 80 may be configured to coat the wire 31 with a pre-mixed epoxy resin at a desirable volumetric rate. The dispense rateof the resin on the wire 31 may be linked to the feed rate of the wire 31. In this manner, the amount of coating material may be adjusted during the winding process.

[0076] The automatic coating dispensing system 80 may comprise a two-part needle assembly including a first needle part 81 and a second needle part 82. The automatic coating dispensing system 80 may further comprise a coating cartridge 83, the coating cartridge 83 being configured to contain a certain amount of the coating material (e.g. a glue-type agent such as epoxy resin or paraffin). The coating dispensing system 80 may further comprise an inlet 84 and an outlet 85, so that the wire 31 can pass through the cartridge 83 and receive the coating material.

[0077] The outlet 85 opening may be dimensioned and shaped such that a controllable thickness of the coating material may be deposited on at least a portion of the wire 31. The amount of coating material may be enough to fill the gaps between turns 33 and layers 34 in the coil 312. Finally, the coating dispensing system 80 may comprise both an inlet 86 and an outlet 87 for the coating material, which may be arranged to replenish the resin cartridge 83 and to control the level of coating material. The material of the needle 80 may be durable for the duration of the winding of the coil 312. Non-limiting examples of suitable materials may include metals, metal alloys, ceramics or tungsten carbide.

[0078] Although not shown in Figure 12, the coating dispensing system 80 may also comprise a coating material preparation system configured to prepare the coating material. This example may be advantageous in case of coating materials comprising a mixture of different substances. Furthermore, a coating monitoring system may also be provided in examples of the disclosure. The monitoring system may be configured to control physical properties of the material such as viscosity. In further examples of the disclosure, an automatic coating dispensing system may be provided. The automatic coating dispensing system may comprise at least one sensor (not shown in the figure) to monitor the coating material level in the cartridge 83 and a controller to control the amount of coating material dispensed into the cartridge 83. In this manner, an automatic replenishing system may be provided to control the level of the coating substance.

[0079] Figure 13 provides an overview of an example of a sytem for manufacturing a coil 312, the system comprising a monitoring unit 91 and a controller unit 90. A movable support 20 and / or a spindle controlling rotation of a mandrel 10 may be communicatively coupled to the controller unit 90. The controller unit 90 may define setpoints for the movable support 20 so as to precisely position a wire feeding assembly 40. Similarly, the rotational speed of the mandrel 10 may also be controlled on the basis of a setpoint generated by the controller unit 90.

[0080] The monitoring unit 91 may comprise a plurality of sensors (91a-91 c), such as but not limited to, a wire tension sensor, a profilometer or a speed sensor. The monitoring unit 91 may be configured to provide real-time feedback of at least one of the following: a position of the wire 31 on the mandrel 10, a rotational position of the mandrel 10, a rotational speed of the mandrel 10, a tension of the wire 31 or a relative position of the wire feeding assembly (40) with respect to a point of contact of the wire (31) with the rotating mandrel (10). The controller unit 90 may be configured to adjust a position of the movable support 20 holding the wire feeding assembly 40 and / or the rotational speed of the mandrel 10. The position of the movable support 20 may be adjusted by providing coordinates for the movable arms and the speed of the mandrel 10 may be adjusted by providing setpoints to the spindle rotating the mandrel 10. Said setpoints may be based on the comparison between the measured position of the wire 31 (as determined, e.g. with a profilometer) and a reference or theoretical position based on a predetermined design. In examples of the disclosure, a plurality of predetermined designs or theoretical patterns may be provided by a coil winding database 92.

[0081] The monitoring unit 91 may be used to detect anomalies in the forming coil 312, e.g. by using a profilometer. Signal processing algorithms may be used to automatically detect anomalies. Alternatively, the profile may be displayed in a GUI (graphical user interface) so that an operator can conduct a verification.

[0082] Figure 14 shows a flowchart of an example of a method 400 for manufacturing a coil 312 with a system like the ones described above. The method 400 comprises, at block 410, fixing an end of a wire 31 at a lead-in position on the surface of a mandrel 10. Block 420 of the method comprises starting rotation of the rotating mandrel 10 while feeding the wire 31 with a wire feeding assembly 40 so that the wire 31 is wound on the rotating mandrel 10. The method further comprises, at block 430, monitoring the relative position of the wire feeding assembly with respect to the point of contact of the wire with either the rotating mandrel 10 or with a previously formed layer of the coil. Finally, block 440 comprises adjusting the position of the wire feeding assembly 40 by moving a movable support 20 holding the wire feeding assembly 40. The movable support 20 is moved so as to ensure that the wire 31 is fed in a substantially horizontal orientation.

[0083] Furthermore, in other examples, a method may also comprise adjusting the position of the wire feeding assembly 40 to ensure that a distance between the wire feeding assembly 40 and the point of contact of the wire 31 with the winding mandrel 10 remains substantially constant. This example method may be particularly advantageous when manufacturing wetwound coils, as the wire 31 may be coated with a coating material (e.g. a glue-type agent such as epoxy resin or paraffin) arranged at the wire feeding assembly 40. By controlling thedistance between the wire feeding assembly 40 and the point of contact of the wire 31 with the mandrel, an improved control of the wetting process may be achieved.

[0084] In still a further example, a method may comprise monitoring the tension of the wire 31 during winding and adjusting the rotational speed of the mandrel 10 relative to the angular position of the mandrel 10 to maintain a substantially constant tension. This example may be specifically useful for non-round coils. Thus, maintaining a consistent tension may be challenging when using non-circular mandrels for the manufacture of non-circular coils, e.g. racetrack shaped coils. In those cases, a precise control of the tension may be difficult to achieve with purely passive systems so the active monitoring of the tension and control of the rotational speed may be beneficial.

[0085] A further example of a method for manufacturing a coil may comprise, before completion of a turn 33, pre-bending the feeding wire 31 in the axial direction to ensure a correct positioning before staring of the next turn 33. Such pre-bending may be favorable to ensure a proper turn-to-turn transition so as to achieve a compact and dense coil 312. The pre-bending may be dimensioned to account for the width of the wire 31 itself and for the intended pitch 36 between turns 33. Pre-bending of the wire 31 may be particularly useful in case of non-helical winding (e.g. circular winding), in which each turn 33 comprises a trajectory substantially parallel to the plane of the mandrel 10 and a short transition region to axially shift the wire 31 for the next turn 33.

[0086] The definition of such an abrupt or short transition region may be difficult to achieve if only relying on the axial displacement of the wire feeding assembly 40. More specifically, manufacturing of wet-wound coils may be especially difficult. For example, the turns 33 of a wire 31 impregnated with epoxy (or other glue-type agent being used as coating material) may be difficult to place at the desired location. The epoxy may reduce the frictional force between the impregnated wire 31 and the mandrel 10 (or forming coil) so that the turns 33 may slip from the desired location. In that sense, the use of such pre-bending before locating the wire 31 on the mandrel 10 may be advantageous. The magnitude of the pre-bending in the case of wetwound coils may be based on the width of the wire 31 and the thickness of the coating material in between turns 33.

[0087] Similarly to the previous example, a further example of a method for manufacturing a coil may comprise adding a step so that, after completing of a layer 34, a bending of the feeding wire 31 in a vertical direction may be carried out to ensure correct positioning before starting of the next layer 34. Thus, by enabling said bending, a pre-bending of the wire is achieved which may facilitate a compact arrangement of the different layers. In case of wet-wound coils, the magnitude of the vertical pre-bending may be based on the thickness of the wire 31 and the thickness of the coating material in between layers 34.

[0088] A further example method may be provided specifically for the manufacture of wetwound coils. In this example, the wire 31 may be coated with a coating material (e.g. glue, epoxy resin, paraffin) before being fed into the rotating mandrel 10. By pre-coating the wire 31 before it is wound on the mandrel 10 (instead of infusing the glue-type material after winding), a more precise and controllable coating may be achieved. Furthermore, in examples comprising pre-bending of the wire 31 , the wire 31 may be coated before being bent in an axial and / or vertical direction by the corresponding pre-bending systems 60, 70.

[0089] This written description uses examples to disclose the teaching, and also to enable any person skilled in the art to practice the teaching, including making and using any devices or systems and performing any incorporated methods. The patentable scope is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims. Aspects from the various examples described, as well as other known equivalents for each such aspects, can be mixed and matched by one of ordinary skill in the art to construct additional examples and techniques in accordance with principles of this application. If reference signs related to drawings are placed in parentheses in a claim, they are solely for attempting to increase the intelligibility of the claim, and shall not be construed as limiting the scope of the claim

Claims

CLAIMS1 . A system for automated fabrication of coils (312), the system comprising: a rotating mandrel (10) configured to rotate about an axis of rotation and to receive a plurality of turns (33) and a plurality of layers (34) of a wire (31); a wire feeding assembly (40) configured to guide and feed the wire (31) to the rotating mandrel (10); and a movable support (20) configured to hold the wire feeding assembly (40) and to move the wire feeding assembly (40) with at least two degrees of freedom substantially in a plane perpendicular to the axis of rotation of the rotating mandrel (10).

2. The system according to claim 1 , wherein the rotating mandrel (10) is substantially racetrack shaped.

3. The system of any of claims 1 or 2, wherein the at least two degrees of freedom comprise two perpendicular directions.

4. The system of any previous claim, wherein the movable support (20) is configured to move the wire feeding assembly (40) in three perpendicular directions, more specifically, in a horizontal (X) and vertical (Z) directions in a plane perpendicular to the axis of rotation of the rotating mandrel (10) and in an axial (Y) direction parallel to the axis of rotation.

5. The system of claim 4, wherein the movable support (20) comprises a horizontal arm (21) for movement of the wire feeding assembly (40) in the horizonal (X) direction, a vertical arm (22) for movement of the wire feeding assembly (40) in the vertical (Z) direction and an axial arm (23) for movement of the wire feeding assembly (40) in the axial (Y) direction, the vertical arm (22) being installed on the horizonal arm (21) and the axial arm (23) being installed on the vertical arm (22).

6. The system of claim 4, wherein the movable support (20) comprises a horizontal arm (21) for movement of the wire feeding assembly (40) in the horizonal (X) direction, a vertical arm (22) for movement of the wire feeding assembly (40) in the vertical (Z) direction and anaxial arm (23) for movement of the wire feeding assembly (40) in the axial (Y) direction, the horizonal arm (21) being installed on the vertical arm (22) and the axial arm (23) being installed on the horizonal arm (21).

7. The system of any previous claim, wherein the wire feeding assembly (40) comprises a wire axial bending system (60) configured to bend the wire (31) in a substantially horizontal direction before the wire (31) is fed to the rotating mandrel (10) and, optionally wherein the wire axial bending system (60) comprises at least a pair of fingers (61a, 61 b, 62a, 62b) configured to engage with the wire (31) so as to twist the wire (31) and induce a pre-bend of the wire (31) in a horizontal direction, the horizontal direction being an axial direction substantially parallel to the rotation axis of the mandrel (10).

8. The system of any previous claim, wherein the wire feeding assembly (40) comprises a wire vertical bending system (70) configured to bend the wire (31) in a substantially vertical direction before the wire (31) is fed to the rotating mandrel (10) and, optionally wherein the wire vertical bending system (70) comprises upper (72) and lower (71) jack clamps configured to bend the wire (31) in the vertical direction.

9. The system of any previous claim, wherein the wire feeding assembly (40) comprises an automatic coating dispensing system (80) configured to coat at least a portion of the surface of the wire (31) before the wire (31) is fed to the rotating mandrel (10) and optionally, wherein the automatic coating dispensing system (80) comprises a coating cartridge (83), the coating cartridge (83) containing the coating material and comprising an inlet (84) and an outlet (85), so that the wire (31) can pass through the cartridge (83) and receive the coating material.

10. The system of any previous claim, the system further comprising: a monitoring unit (91) configured to provide real-time feedback of at least one of the following: position of the wire (31) on the mandrel (10), a rotational position of the mandrel (10), a rotational speed of the mandrel (10), a tension of the wire (31) or a relative position of the wire feeding assembly (40) with respect to a point of contact of the wire (31) with the rotating mandrel (10); and a controller unit (90) configured to adjust the position of the movable support (20) supporting the wire feeding assembly (40) and / or the rotational speed of the mandrel (10).

11. A method for manufacturing a coil (312) with a system according to any of claims 1 to 9, the method comprising: fixing an end of a wire (31) at a lead-in point on the surface of the rotating mandrel (10); starting rotation of the rotating mandrel (10) while feeding the wire (31) with the wire feeding assembly (40) so that the wire (31) is wound on the rotating mandrel (10); monitoring the relative position of the wire feeding assembly (40) with respect to a point of contact of the wire (31) with eitherthe rotating mandrel (10) or with a previously formed layer (34) of the coil (312); and adjusting the position of the wire feeding assembly (40) by moving the movable support (20) so as to ensure the wire (31) is fed in a substantially horizontal orientation.

12. The method of claim 11 , the method further comprising adjusting the position of the wire feeding assembly (40) to ensure that a distance between the wire feeding assembly (40) and the point of contact of the wire (31) with the winding mandrel (10) remains substantially constant.

13. The method of any of claims 11 or 12, the method further comprising adjusting the rotational speed of the rotating mandrel (10) relative to its angular position to maintain a substantially constant tension.

14. The method of any of claims 11 to 13, the method comprising, before completion of a turn (33), pre-bending the feeding wire (31) in the axial direction, and / or after completion of a layer (34), pre-bending the feeding wire (31) in a vertical direction.

15. The method of any of claims 11 to 14 wherein the wire (31) is coated with a coating material before being fed to the rotating mandrel (10) and, optionally, wherein the wire (31) is bent in an axial and / or vertical direction and the wire (31) is coated before being bent.

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