Apparatus for cutting and welding flat wire stator conductor hairpins

Abstract

An apparatus for cutting and welding wire hairpin ends (W) of a motor stator. The apparatus is configured as a single station including at least one cutting set (1) for jointly cutting a plurality of wire hairpin ends (W), in order to obtain wire square flat ends protruding from the core, and at least one welding set (2) configured for welding the wire hairpin ends (W) previously cut by means of the cutting set (1).

Description

[0001] “APPARATUS FOR CUTTING AND WELDING FLAT WIRE STATOR CONDUCTOR HAIRPINS”

[0002] TECHNICAL FIELD

[0003] The present invention generally refers to apparatus and methods for the manufacture of electrical machines, and relates in particular to cutting and welding operations of a plurality of wire hairpin ends protruding from a core of a component for an electrical machine, in particular a stator.

[0004] BACKGROUND

[0005] As is known, hairpin technology is a winding technology applied in the field of electric motors, based on solid, flat copper bars configured for being inserted into a stator stack. These copper bars, so-called “hairpins”, consist of enameled copper wire bent into a U-shape.

[0006] According to a conventional technique, after inserting the hairpins into a core of a component for an electrical machine, such as a stator, it is necessary to perform a cutting operation for cutting a plurality of wire hairpin ends protruding from the core, in order to obtain a flat end surface cut from the flat wire for subsequent welding. After the cutting operation, it is necessary to perform a welding operation to ensure efficient and reliable joining of the flat wire stator hairpin ends and to form electrically conductive joints that can withstand mechanical stresses and thermal cycling during the operation of the motor.

[0007] The present invention starts from the desire to provide an apparatus of the type indicated above, improving the known solutions from various points of view, in particular production efficiency and precision of the operations.

[0008] SUMMARY

[0009] In order to achieve the above-mentioned object, the present invention is directed to an apparatus for cutting and welding flat wire stator hairpins, comprising:

[0010] - a structural frame for supporting at least one cutting set and at least one welding set vertically spaced one from the other along the frame, - a movable carriage vertically slidably mounted on the structural frame between a cutting position and a welding position, wherein the carriage comprises a vertical plate coupled with the frame and a horizontal platform on which is clamped a core of the stator, for carrying out cutting and welding operations,

[0011] - a lift actuator for driving a vertical movement of the carriage between the cutting position and the welding position,

[0012] - a rotation actuator configured for driving in rotation the platform of substantially 180° around a horizontal symmetry central axis of the platform, during the vertical movement driven by the lift actuator, for orienting wire hairpin ends previously cut by means of the cutting set towards the welding set for carrying out the welding operation,

[0013] - wherein said least one cutting set includes:

[0014] - a first disc having a plurality of equidistant spiral grooves, and a second disc having a plurality of equidistant linear radial grooves, wherein the second disc is axially arranged above the first disc, so that the two discs have a central common axis,

[0015] - a plurality of radial cam cutter assemblies carried by the two discs and arranged around said central common axis, wherein each cam cutter assembly comprises a blade having a cutting edge directed towards said central common axis, and a linear drive support element including a cutter holder and a cam, wherein the cams are mounted into the equidistant spiral grooves, and the cutter holders are radially slidably mounted within the linear radial grooves,

[0016] - an actuator unit configured for driving in rotation the first disc, in order to cause a simultaneous radial movement of the blades for jointly cutting wire hairpin ends protruding from the core,

[0017] - in such a way that the apparatus is configured as a single station including at least one cutting set for jointly cutting a plurality of wire hairpin ends, in order to obtain wire square flat ends of the flat wire stator, and at least one welding set configured for welding the wire hairpin ends previously cut by means of the cutting set.

[0018] The present invention is also directed to a method for cutting and welding flat wire stator hairpin ends, comprising:

[0019] - locking a flat wire on the carriage,

[0020] - positioning the carriage in the cutting position of the flat wire stator hairpins,

[0021] - driving in rotation the first disc, in order to cause a simultaneous radial movement of the blades for jointly cutting wire hairpin ends of the core, - sliding the carriage from the cutting position to the welding position, - during the movement of the carriage towards the welding set, rotating the platform so that the cut ends are oriented towards the welding set, for carrying out the welding operation.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Further characteristics and advantages of the invention will become apparent from the description that follows with reference to the attached drawings, provided purely byway of a non-limiting example, wherein:

[0024] - Figure 1 is a perspective view of an apparatus for cutting and welding wire hairpin ends according to a configuration method of the present invention;

[0025] - Figure 2 shows a structural frame illustrated in Figure 1 ;

[0026] - Figure 3 shows a lifting push rod assembly illustrated in Figure 1; - Figure 4A shows a clamping of the stator and flat wire hairpin ends by the platform device in Figure 1 ;

[0027] - Figures 4B - 4E show further details of the hairpin end clamping device;

[0028] - Figure 5 shows a rotation actuator illustrated in Figure 1 ;

[0029] - Figure 6 shows a cutting set illustrated in Figure 1 ;

[0030] - Figures 7-9 show additional structures of the cutting set,

[0031] - Figure 10 shows a welding set illustrated in Figure 1;

[0032] - Figure 11 shows a suction device illustrated in Figure 1; and

[0033] - Figure 12 is a perspective view of an apparatus for cutting and welding wire hairpin ends, according to additional exemplary embodiments of the present invention.

[0034] DETAILED DESCRIPTION

[0035] In the following description, various specific details are illustrated aimed at a thorough understanding of examples of one or more device configurations. The device configurations may be implemented without one or more of the specific details, or with other methods, components, materials, etc. In other cases, known structures, materials or operations are not shown or described in detail to avoid obscuring various aspects of the device configurations. The reference to “a configuration embodiment” in the context of this description indicates that a particular configuration, structure or characteristic described in relation to the configuration embodiment is included in at least one configuration embodiment. Therefore, phrases such as “in a configuration embodiment”, possibly present in different places of this description do not necessarily refer to the same configuration embodiment. Moreover, particular conformations, structures or characteristics can be combined in a suitable manner in one or more configurations and / or associated with the configuration embodiments in a different way from that illustrated here, for example, a characteristic here exemplified in relation to a figure may be applied to one or more configuration embodiments exemplified in a different figures. The references illustrated here are only for convenience and do not therefore delimit the field of protection or the scope of the configurations.

[0036] The present invention relates to an apparatus for cutting and welding flat wire stator conductor hairpin ends W

[0037] As illustrated in Figure 1 , the apparatus of the present invention is configured as a single station including at least one cutting set 1 for jointly cutting a plurality of flat wire stator hairpin ends, in order to obtain wire square flat ends, and at least one welding set 2 configured for joining the hairpin ends previously cut by means of the cutting set 1. The apparatus of the present invention is configured as a single station provided for incorporation into a manufacturing line for producing stators of an electrical machine. At least one control unit is provided for controlling the apparatus, to carry out cutting and welding operations of the wire hairpin ends W.

[0038] According to Figures 1 and 2, the apparatus configured as a single station comprises a structural frame 3 carrying both the at least one cutting set 1 and the at least one welding set 2, vertically spaced one from the other along the frame 3.

[0039] The structural frame 3 comprises a base frame 4 having a front interface portion 4’ provided for carrying the cutting set 1 , and a main frame 5 coupled with and located above the base frame 4, having an upper section 6 provided for carrying the welding set 2. The upper section 6 comprises a front mounting surface having a top portion 7 for mounting the welding set 2 and a front intermediate portion 8 for mounting a suction device 9 further described in the following. Therefore, according to preferred configuration embodiments, the cutting set 1 is vertically spaced from the welding set 2, below the welding set 2, and the suction device 9 is associated with the welding device 2, below a welding device 28.

[0040] The main frame 5 includes two vertical columns 10 along which a movable carriage 11 is configured to support the stator S, and vertically move the stator S from the cutting set 1 to the welding set 2, and vice versa. Therefore, the carriage 11 is vertically movable between a cutting position (for operation of the cutting set 1) and a welding position (for operation of the welding set 2).

[0041] As illustrated in Figure 3, the carriage 11 may comprise a vertical plate 1T spaced between the vertical columns 10, having two side surfaces 11” slidably mounted along the respective vertical column 10. These features allow for a seamless workflow: first, the wire hairpin ends W are cut using the cutting set 1 located at the lower part of the structural frame 3. Once the cutting process is complete, the movable carriage 11 ascends smoothly to position the stator S for the welding operation, which takes place at the upper part of the structural frame 3. This integrated approach ensures efficiency and precision in processing the wire hairpin ends W.

[0042] According to Figures 1 and 3, the apparatus comprises at least one lift actuator 12 for driving the vertical movement of the carriage 11. Preferably, the lift actuator 12 is a servo cylinder including a piston rod 13 that extends and retracts to facilitate the movement of the carriage 11. This rod 13 is integral to the operation of the servo cylinder, providing the necessary force to move the carriage 11 up and down along the structural frame 3. As the servo cylinder is activated, the rod 13 moves in a linear motion, allowing for precise control over the positioning of the stator S. The rod 13 is connected to the carriage 11 through a connecting block 14. As previously indicated, the carriage 11 may comprise a plate 1T spaced between the vertical columns 10, having two side surfaces slidably mounted along the respective vertical column 10. The plate 11 has an upper side centrally connected to the connecting block 14.

[0043] According to Figures 1 and 4A, the movable carriage 11 comprises a horizontal platform 15 provided for connection with the plate 11 having a clamping section 30 on which is clamped the core of the stator S, for carrying out cutting and welding operations. Therefore, by driving the vertical movement of the carriage 11 , both the plate 1T and the horizontal platform 15 (carrying the stator S) vertically slide along the columns 10.

[0044] As previously indicated, the horizontal platform 15 has a clamping section 30 on which is clamped the core of the stator S. According to Figures 1 and 4A-4E, the horizontal platform 15 carries locking means for clamping the wire hairpin ends W to be processed, and for clamping the core at the clamping section 30. The clamping section 30 comprises a circular receptacle for receiving the core. In association with the circular receptacle, the locking means comprise a lower disc 31 and an upper disc 32 mutually superimposed, both having respective wire openings 33 for receiving wire hairpin ends W protruding from a lower side of the core, in such a way that the wire hairpin ends W extends beyond the wire openings 33, downwardly the lower disc 31. In this connection, the horizontal platform 15 carries a first locking pushing rod 34 for clamping and releasing the wire hairpin ends W extending beyond the wire openings 33, and a second pushing cylinder 35 for clamping and releasing the core at the clamping section 30. The pushing rod 34 drives in rotation the discs 31 and 32, so as to clamp the wire hairpin ends W preliminary to cutting and welding operations. The pushing cylinder 35 is configured to drive a connected lever to clamp the core and keep the stator S unmoved during the whole process of cutting and welding.

[0045] According to Figures 1 and 5, the apparatus comprises a rotation actuator 16 connected to the platform 15, configured for driving in rotation the platform 15 of 180° around a horizontal symmetry central axis of the platform 15, during the vertical movement driven by the lift actuator 12. The rotation actuator 16 is an electric motor having an operational shaft connected to a vertical back wall 15’ of the platform 15; the electric motor has a main body supported by the vertical plate 1T which incorporates an opening 1T” for receiving at least partially the main body with the operational shaft protruding from the opening for connection with the platform 15.

[0046] In operation, the carriage 11 is configured for vertical slides between a lower position (above the cutting set 1) and an upper position (below the welding set 2); the cutting set 1 is configured at a lower end; during the upward movement of the carriage 11 towards the welding set 2, the platform 15 is rotated of 180° around a horizontal symmetry central axis of the platform 15; this rotation ensures that the cut ends are oriented towards the upper welding set 2, for carrying out the welding operation. This integrated mechanism enhances efficiency by facilitating a smooth transition from cutting to welding.

[0047] According to Figures 6-9, the cutting set 1 comprises a support base 17, a first disc 18 having a plurality of equidistant spiral grooves 19, and a second disc 20 having a plurality of equidistant linear grooves 21 , preferably T-shaped. The first disc 18 is arranged on the support base 17 and the second disc 20 is superimposed above the first disc 18, so that the two discs 18 and 20 have a central common axis, directed along a vertical direction parallel to the vertical columns 10. The cutting set 1 further comprises a plurality of radial cam cutter assemblies 22 arranged around the central common axis, carried by the two discs 18, 20 as further explained below. As shown in Figures 7-9, each cam cutter assembly 22 comprises a blade 23 having a cutting edge directed toward the central axis of the cutting set 1, and a linear drive support element 24 for supporting and driving a movement of the blade 23 along the radial direction of the discs 18, 20, towards of the central axis and away from the central axis. Each linear drive support element 24 comprises a cutter holder and a cam 25. The cam cutter assemblies 22 are respectively mounted into the linear grooves 21 of the second disc 20, and the cams 25 are respectively mounted into the equidistant spiral grooves 19.

[0048] Due to this arrangement, the cutter holders and the blades are radially slidably mounted within the linear grooves of the second disc 20. The spiral grooves 19 are configured in such a way that a rotation of the first disc 18 between two end positions causes the cam cutter assembly 22 to be driven by the spiral grooves 19 and results a radial movement of each cam cutter assembly 22 between two end positions, The operating method and principle of the spiral grooves 19 are such that a rotation of the first disc 18 at a constant speed causes a radial movement of the cam cutter assemblies 22 at a constant speed. Accordingly, a rotation movement of the first disc 18 will cause a consequent radial movement of the blades 23. The blades 23 are connected to the respective cutter holder, by means of at least one removable connecting element, such as a screw, in order to avoid having to replace the entire cam cutter assembly 22, in case of damage to the blade 23.

[0049] The cam 25 is directly fastened to the cutter holder, and the tail end of the cutter holder is tightened by a jackscrew to prevent loosening and falling off during the movement.

[0050] Each spiral groove 19 is engaged by two cams 25 carried by two adjacent cutter holders. Therefore, the number of spiral grooves 19 is half the number of the cam cutter assemblies 22. The number of the cam cutter assemblies 22 is equal to the number of the linear grooves 21 of the second disc 20. Therefore, considering one second disc 20 having 48 linear grooves, 48 cam cutter assemblies 22 are provided, respectively engaged with 24 spiral grooves 19 of the first disc 18. Due to the above-indicated arrangement, two adjacent cutter holders engaged within the same spiral groove, have different lengths (in order to provide one long cutter holder and one short cutter holder).

[0051] The cam cutter assemblies 22 are provided on the two discs 18 and 20 so that all the cutting edges result equally distanced from the common central axis of the discs 18,20.

[0052] The cutting set 1 comprises a motor transmission 26, for driving in rotation the first disc 18, in order to cause a consequent simultaneous radial movement of the blades 23, for jointly cutting a plurality of flat wire stator hairpin ends W, in order to obtain wire square flat ends of the stator. In operation, the cam cutter assemblies 22 uniformly slide along the linear grooves 21 of the second disc 20, synchronously and centripetally to shear the excessive material wire (copper) to achieve the effect of flat shearing.

[0053] According to Figure 9, the cutting set 1 comprises a support flange 27 located at a central empty area of the discs 18, 20, configured for positioning and locking the core of the stator S, with lower hairpin ends W of the core ready for the cutting operation.

[0054] According to possible embodiments, the cutting set 1 may comprise a waste funnel and a cutting waste pipeline connected below the cutting waste funnel. In operation, after cutting the flat copper wire ends, the cut material may be wasted by gravity through the waste funnel. According to the features previously described, the present invention provides an efficient and fast flat cutting process, with a fast production rate, and good reliability; the expanding and retracting accuracy of the blades -along the radial direction of the discs - is extremely high, and the linear grooves are used for precisely matching and sliding the cam cutter assemblies, so that the structure of the cutting device results relatively simple and compact. The cutting operation results particularly efficient and quick. Also, replacement of blades results relatively easy to perform. The cutting set is easy to disassemble and repair, and at the same time is flexibly applicable to robotic manipulators with gantry type mechanism.

[0055] According to Figures 1 and 10, the welding set 2 comprises a welding device 28, to ensure the efficient and reliable joining of hairpin ends protruding from the core of stators in electric machines. The primary objective is to create strong, electrically conductive joints that can withstand mechanical stresses and thermal cycling during the operation of the motor. The welding device 28 is a galvanometer laser device, which allows for precise and controlled laser welding of the wire hairpin ends W. The laser source is securely housed within a protective enclosure, ensuring safety and stability during operation. The optical path is designed to minimize distortion and maximize beam quality, with components such as lenses and beam expanders that focus the laser for optimal welding performance.

[0056] Additionally, the welding set 2 may be integrated with sensors to monitor parameters such as temperature and weld quality, allowing for realtime adjustments to ensure consistent results. The overall design emphasizes durability and precision, making it an effective solution for high-quality welding applications.

[0057] According to Figures 1 and 11 , the welding set 2 comprises a suction device 9 provided for capturing and extracting waste material, such as metal debris generated during the welding of the wire hairpin ends W. It ensures a clean working environment by efficiently removing contaminants from the immediate welding area, preventing the accumulation of particles and enhancing operator safety. The suction device 9 is spaced below the welding device 28, and configured for receiving the smoke and splashes generated by welding the stator S when the carriage 11 is located in the welding position. As previously indicated, the apparatus of the present invention is configured as a single station including at least one cutting set 1 and at least one welding set 2.

[0058] Possible embodiments in this respect are shown in Figure 12, wherein the structural frame 3 comprises two or more sections, each having one independent carriage 11 vertically slidable along respective vertical columns 10. In order to maximize production rate, the cutting set 1 and the welding set 2 may be independently slidable on respective support portions T, 2’ along a horizontal direction perpendicular to the vertical direction, for operating on one respective carriage 11 of one frame section, carrying one respective stator S to be processed. In this respect, it is to be noted that each section of the frame 3 may be provided with one respective static suction device 9. Therefore, in operation, the cutting set 1 and the welding set 2 may simultaneously operate on two different carriages 11 I stator S.

[0059] Naturally, other embodiments in this respect may be provided, in which each section is provided with one respective cutting set 1 , and only the welding set 2 slides along the horizontal direction, or vice versa.

[0060] Finally, it should be noted that the above description is only preferred embodiments of the present invention and is not intended to limit the present invention. Although the present invention is described in detail with reference to the foregoing embodiments, a person of skill in the art can still make modifications to the technical solutions described in the foregoing embodiments, or make equivalent replacements to some of the technical features, and any modifications and equivalent replacements and improvements made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

CLAIMS1. An apparatus for cutting and welding wire hairpin ends (W) of a motor stator, comprising:- a structural frame (3) for supporting at least one cutting set (1) and at least one welding set (2) vertically spaced one from the other along the frame (3),- a movable carriage (11) vertically slidably mounted on the structural frame (3) between a cutting position and a welding position, wherein the carriage (11) comprises a vertical plate (11’) coupled with the frame (3) and a horizontal platform (15) on which is clamped a core of the stator (S), for carrying out cutting and welding operations,- a lift actuator (12) fordriving a vertical movement of the carriage (11) between the cutting position and the welding position,- a rotation actuator (16) configured for driving in rotation the platform (15) of substantially 180° around a horizontal symmetry central axis of the platform (15), during the vertical movement driven by the lift actuator (12), for orienting wire hairpin ends (W) previously cut by means of the cutting set (1 ) towards the welding set (2) for carrying out the welding operation, - wherein said least one cutting set (1 ) includes:- a first disc (18) having a plurality of equidistant spiral grooves (19), and a second disc (20) having a plurality of equidistant linear radial grooves (21), wherein the second disc (20) is axially arranged above the first disc (18), so that the two discs (18,20) have a central common axis,- a plurality of radial cam cutter assemblies (22) carried by the two discs (18,20) and arranged around said central common axis, wherein each cam cutter assembly (22) comprises a blade (23) having a cutting edge directed towards said central common axis, and a linear drive support element (24) including a cutter holder and a cam (25), wherein the cams (25) are mounted into the equidistant spiral grooves (19), and the cutter holders are radially slidably mounted within the linear radial grooves (21), - an actuator unit (26) configured for driving in rotation the first disc (18), in order to cause a simultaneous radial movement of the blades (23) for jointly cutting wire hairpin ends (W) protruding from the core,- in such a way that the apparatus is configured as a single stationincluding at least one cutting set (1) for jointly cutting a plurality of wire hairpin ends (W), in order to obtain wire square flat ends of a stator hairpin, and at least one welding set (2) configured for welding the wire hairpin ends (W) previously cut by means of the cutting set (1 ).

2. The apparatus according to claim 1 , wherein the structural frame (3) comprises a base frame (4) having a front interface portion (4’) provided for carrying the cutting set (1), and a main frame (5) coupled with and located above the base frame (4), having an upper section (6) provided for carrying the welding set (2).

3. The apparatus according to claim 1 , wherein the rotation actuator (16) is an electric motor having an operational shaft connected to a vertical back wall (15’) of the platform (15), the electric motor having a main body supported by the vertical plate (11’) which incorporate an opening (11’”) for receiving the main body with the operational shaft protruding from the opening (11 ’”) for connection with the platform (15).

4. The apparatus according to claim 1 , wherein the blades (23) are connected to the respective cutter holder, by means of a removable connecting element, such as a screw, in order to avoid having to replace the entire cam cutter assembly (22) in case of damage of the blade (23).

5. The apparatus according to claim 1 , wherein each spiral groove (19) is engaged by two cams (25) carried by two adjacent cutter holders.

6. The apparatus according to claim 5, wherein said two adjacent cutter holders have a different length, so that all the cutting edges result equally distanced from the common central axis of the discs (18,20).

7. The apparatus according to claim 1, comprising a cutting waste funnel and a cutting waste pipeline connected below the cutting waste funnel, so that in operation, after cutting the wire ends, the cut material is wasted by gravity through the waste funnel.

8. The apparatus according to claim 1 , wherein the welding set (2) comprises a laser galvanometer welding device, and a suction device (9) provided for capturing and extracting waste material, such as metal debris generated during the welding of the wire hairpin ends (W).

9. The apparatus according to claim 1 , wherein the structural frame (3) comprises two or more sections, each having one independent carriage (11) vertically slidable along respective vertical columns (10) of the frame(3).

10. The apparatus according to claim 9, wherein each section is provided with one cutting set (1 ), one welding set (2), and one carriage (11).

11. The apparatus according to claim 9, wherein the cutting set (1) and / or the welding set (2) are independently slidable on respective support portions (T, 2’) of the frame (3) along a horizontal direction, so that in operation, the cutting set (1) and the welding set (2) may simultaneously operate on two different carriages (11 ) / stator (S).

12. The apparatus according to claim 1, wherein, the horizontal platform (15) has a clamping section (30) on which is clamped the core of the stator (S), in association with locking means for clamping the wire hairpin ends (W) to be processed.

13. A method for cutting and welding wire hairpin ends (W) of a motor stator, comprising:- providing an apparatus according to claim 1 ,- locking a stator (S) on the carriage (11),- positioning the carriage (11) in the cutting position,- driving in rotation the first disc (18), in order to cause a simultaneous radial movement of the blades (23) for jointly cutting wire hairpin ends (W) protruding from the core,- sliding the carriage (11) from the cutting position to the welding position,- during the movement of the carriage (11) towards the welding set (2), rotating the platform (15) so that the cut ends are oriented towards the welding set (2), for carrying out the welding operation,- actuating the welding set (2) for welding the wire hairpin ends (W) previously cut by means of the cutting set (1 ).

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