Method for manufacturing a ferromagnetic core for an electric motor

Abstract

The present invention relates to a method for manufacturing a ferromagnetic core for an electric motor, wherein the ferromagnetic core is formed by a plurality of stacked segments, the plurality of stacked segments being composed of bundled stacked sheets, the plurality of stacked segments being connected together in a closed circular configuration during punching of each stacked sheet layer to form a complete ferromagnetic core of a circular configuration and being connected together with the possibility of rotation so as to be able to switch from the closed circular configuration to an open linear configuration, and vice versa, wherein each of the plurality of stacked segments has the shape of an arc, has an inwardly protruding polarity expansion portion and a yoke seat arranged on the outside relative to the central axis of the ferromagnetic core, wherein the stacked sheets of each of the plurality of stacked segments are connected together by a crimping portion, and wherein at least a portion of each of the plurality of stacked segments is connected to an adjacent stacked segment along the yoke seat with the possibility of reciprocating rotation.

Description

Technical Field

[0001] The invention relates to a method for producing a ferromagnetic core for an electric motor, the core consisting of bundles of laminated sheets, in particular a ferromagnetic core formed from a plurality of bundles in the form of segments which are mechanically separated from one another and connected to one another. Background Art

[0002] Ferromagnetic cores of electric motors made by stacking a plurality of metal laminations are known in the art. In detail, the cylindrical cores of the stator and rotor of such electric motors are made by punching out substantially annular laminations from a foil of ferromagnetic material and then by bundling an appropriate number of laminations to obtain a core of the desired axial length.

[0003] In detail, in particular with regard to the stator core, it is also known in the art to manufacture the stator core in the form of a plurality of segments formed according to a closed circular configuration and thus assuming an open rectilinear configuration to facilitate the winding of the coils on the respective polar expansions. Once the winding is completed, the rectilinear configuration must be able to be folded to assume a closed circular shape in order to be inserted into the housing or cylindrical housing of the electric motor.

[0004] Patent application EP-A1-2309621 describes a method for forming, for example, a ferromagnetic stator core for an electric motor, formed from a plurality of laminated segments formed from a punched foil so as to form laminates arranged in a circular configuration, or in other words, in a "closed chain" configuration. Each laminated segment generally has the shape of an arc of a circle, with a polar expansion protruding inwards and a yoke seat arranged on the outside relative to the central axis of the ferromagnetic core. The laminates of each laminated segment are connected together by a crimping portion. In addition, each laminate has an embossed pin portion obtained by causing a punch to act on one end of each yoke seat, which then engages with a cavity formed by the punch itself in the laminate below; however, at the other end of the yoke seat, a recess is provided, which allows the laminate of the adjacent segment to engage with the cavity of the laminate below. Thus, a hinge is obtained extending substantially along the entire axial length of the core, allowing reciprocating rotation between adjacent segments, the purpose of which is to allow the successive steps of winding conductor coils on the polar extensions of the segments after the segments are arranged in a straight line.

[0005] However, the coupling of the pins of the laminates with the cavities of the laminates below is an interference coupling, i.e. the same type of coupling occurs between the crimps and the corresponding cavities to secure each laminate to the laminate below or above. A hinge obtained with a similar type of coupling along the entire axial length of the core would make rotation between the segments difficult, especially when the segments are long.

[0006] Furthermore, punching the pins on all the laminations constituting the segment reduces productivity and causes rapid wear of the punch and the corresponding die.

[0007] US2010 / 066193 describes a stator core formed by several stacked segments connected together according to a closed circular configuration. Each stacked segment generally has an arc shape and has an inwardly protruding polarity extension and a yoke seat arranged on the outside relative to the central axis of the stator core. The stacked segments are all connected together in a closed chain configuration and therefore cannot be turned into an open straight line configuration. However, each segment can be slightly rotated and translated relative to the adjacent segments to move the polarity extension of the adjacent segments away relative to the polarity extension of the segment on which the conductor must be wound.

[0008] The document does not describe in depth the method of manufacturing a similar stator core, but does specify:

[0009] - the segments including the yoke seat and the polar extension are formed one after the other;

[0010] - a single segment including the yoke and the polar extension only forms a circular configuration when assembled;

[0011] Each segment is formed by a specific number of laminates, in particular twelve in the example described, which are connected to one another by crimping in the thickness direction to form each single segment comprising a yoke and a polar expansion.

[0012] It is therefore apparent that manufacturing a similar stator core requires the steps of blanking and connecting the laminations to form the individual segments, and a separate step of assembling the individual segments to form the final closed chain configuration.

[0013] Other documents, such as US2017 / 117761, JP2015-223060 and JP2016-077154, disclose how to assemble individual segments together one after another to make a stator core. Summary of the invention

[0014] As stated above, a general object of the present invention is to provide a method of manufacturing a ferromagnetic core for an electric motor formed from a plurality of segments, which method overcomes the limitations of the known art.

[0015] A particular object of the invention is to provide a method allowing the manufacture of a ferromagnetic core for an electric motor, wherein the segments can be easily rotated relative to each other in order to pass from a closed circular state to an open rectilinear state and vice versa.

[0016] Another specific object of the invention is to provide a method of the above-mentioned type which produces segments of ferromagnetic cores having a reduced magnetic resistance compared to the prior art.

[0017] These and other objects are achieved by the present invention, which relates to a method according to claim 1 for producing a ferromagnetic core for an electric motor formed from a plurality of segments. Other special features of the invention are set forth in the corresponding dependent claims.

[0018] The object of the method of the present invention relates to the manufacture of a ferromagnetic core for an electric motor, the ferromagnetic core being formed of a plurality of stacked segments consisting of bundled laminates, the stacked segments being connected together to form a closed circular configuration during the punching of each layer of laminates. Each stacked segment is roughly in the shape of an arc of a circle, having an inwardly protruding polar extension and a yoke seat arranged on the outside relative to the central axis of the ferromagnetic core. The laminates of each stacked segment are connected together by crimping to form a compact bundle of laminates, and at least a portion of the stacked segment is connected to an adjacent segment along the yoke seat and is capable of reciprocating rotation. The only separated segments are the first and last in the closed circular configuration.

[0019] The method comprises the following steps:

[0020] a) feeding the ferromagnetic material foil along the punching station and the die-stamping station of the punching / die-stamping device;

[0021] b) forming one or more crimping portions and corresponding cavities by punching the laminated sheets of each segment;

[0022] c) punching out initial layers of the laminate in a closed circular configuration of the ferromagnetic core and pushing them into the accumulation chamber of the punching die of the punching / pressing device;

[0023] d) punching out a plurality of intermediate layers of the laminated sheets in a closed circular configuration of the ferromagnetic core, and coupling the protruding crimping portions of each intermediate layer of the laminated sheets with the corresponding cavities of the laminated sheets of the next layer, so as to stack each punched intermediate layer on the laminated sheets of the next layer in the accumulation chamber of the punching die of the punching / pressing device,

[0024] e) Punching out the end layer of the laminate in the closed circular configuration of the ferromagnetic core and pushing it into the accumulation chamber of the punching die by coupling the raised crimping portions of the end layer of the laminate with the corresponding cavities of the next layer of laminate.

[0025] Each of the stacked segments arranged in a closed circular configuration is formed by a stacked sheet having a concave portion at one end of the yoke seat of each segment and a convex portion at the other end of the yoke seat of each segment. The concave and convex portions have complementary shapes and sizes.

[0026] The method according to the present invention further comprises the following steps:

[0027] f) embossing a pin portion in at least one first auxiliary layer of the laminate forming each of the laminate segments, in the vicinity of a projection at one end of the yoke;

[0028] g) further punching a recess in the first auxiliary layer of the laminated sheet at the other end opposite to the yoke, wherein the laminated sheet forms each of the laminated segments; and

[0029] h) punching an opening in at least one second auxiliary layer of the laminated sheet forming each of the laminated segments near a projection at one end of the yoke.

[0030] The first and second auxiliary layers are consecutive layers in a bundle of laminate sheets forming each of the laminate segments of the core, and wherein the pin portions of the first auxiliary layer of laminate sheets engage with the openings of the second auxiliary layer of laminate sheets.

[0031] Furthermore, therefore, only one pair of auxiliary layers is sufficient to form ferromagnetic core segments which are reciprocally rotatable relative to the pins formed by the first auxiliary layer in each segment.

[0032] The openings formed in the second auxiliary layer of the laminate consist of notches. Advantageously, this also allows a slight translation between the segments, thereby facilitating the transformation of the segments from a closed circular configuration to an open rectilinear configuration and vice versa.

[0033] In a possible embodiment of the method, a first auxiliary layer of laminates and a second auxiliary layer of laminates are arranged between intermediate layers of laminates of the ferromagnetic core, which consists of a plurality of laminate segments arranged in a closed circular configuration.

[0034] In another embodiment of the method, in the ferromagnetic core, the first auxiliary layer of the laminate is arranged as an initial layer, and the second auxiliary layer of the laminate is coupled to an intermediate layer of the laminate directly above it, wherein the ferromagnetic core is composed of a plurality of laminate segments arranged in a closed circular configuration.

[0035] In another embodiment of the method, in the ferromagnetic core, the first auxiliary layer of the laminate is arranged as an end layer, and the second auxiliary layer of the laminate is coupled to an intermediate layer of the laminate directly below it, wherein the ferromagnetic core is composed of a plurality of laminate segments arranged in a closed circular configuration.

[0036] In other embodiments of the method, a plurality of first auxiliary layers and second auxiliary layers are formed, the number of the first auxiliary layers and the second auxiliary layers corresponds and are coupled. Each of the first auxiliary layers and each of the second auxiliary layers is coupled to one of the intermediate layers of the stack, or to the initial layer of the stack, or to the terminal layer of the stack.

[0037] According to the present invention, there is also provided a ferromagnetic core of an electric motor, the ferromagnetic core being formed by a plurality of stacked segments, the plurality of stacked segments being composed of a bundle of laminations, the stacked segments being connected together in a closed circular configuration during the punching of each lamination layer, wherein each of the stacked segments generally has the shape of an arc, having an inwardly protruding polar expansion portion and a yoke seat arranged on the outside relative to the central axis of the ferromagnetic core. The laminations of each stacked segment are connected together by a crimping portion, and at least a portion of the stacked segment is connected to an adjacent segment along the yoke seat and is reciprocatingly rotatable. The ferromagnetic core comprises an initial layer of laminations, a plurality of intermediate layers of laminations, and an end layer of laminations, which are stacked together to form a plurality of stacked segments in a closed circular configuration of the ferromagnetic core.

[0038] The lamination layers forming each stacked segment arranged in a closed circular configuration have a concave portion and a convex portion, the concave portion being located at one end of the yoke seat of each segment and the convex portion being located at the other end of the yoke seat of each segment; the concave portion and the convex portion having complementary shapes and sizes. The ferromagnetic core comprises a first auxiliary layer of laminations and a second auxiliary layer of laminations, the first auxiliary layer having a protruding pin portion and a concave portion, the protruding pin portion being located near the convex portion at one end of the yoke seat of the laminations forming each stacked segment, the concave portion being located at the opposite end of the yoke seat in the first auxiliary layer of laminations forming each stacked segment, and the second auxiliary layer having an opening, the opening being located near the convex portion at one end of the yoke seat of the laminations forming each stacked segment. The first auxiliary layer and the second auxiliary layer of laminations are continuous layers in the lamination bundle forming each stacked segment of the core, and the pin portion of the first auxiliary layer of laminations engages at the opening of the second auxiliary layer of laminations.

[0039] The opening formed in the second auxiliary layer of the lamination stack advantageously consists of a notch.

[0040] In one embodiment of the ferromagnetic core, the first auxiliary layer of the laminate and the second auxiliary layer of the laminate are arranged between intermediate layers of the laminate of the ferromagnetic core, the ferromagnetic core being formed by a plurality of laminated segments arranged in a closed circular configuration.

[0041] In another embodiment of the ferromagnetic core, the first auxiliary layer of the laminate is an initial layer and the second auxiliary layer of the laminate is coupled to an intermediate layer of the laminate located directly above in the ferromagnetic core, the ferromagnetic core being formed by a plurality of laminated segments arranged in a closed circular configuration.

[0042] In another embodiment of the ferromagnetic core, the first auxiliary layer of the lamination is an end layer of the lamination and the second auxiliary layer of the lamination is coupled to an intermediate layer of the lamination directly below in the ferromagnetic core, the ferromagnetic core being formed by a plurality of lamination segments arranged in a closed circular configuration.

[0043] In other possible embodiments of the ferromagnetic core, a plurality of first auxiliary layers coupled to a corresponding number of second auxiliary layers are arranged. Each of the first and second auxiliary layers can be coupled to one of the middle layers of the stack, or to the initial layer of the stack, or to the end layer of the stack.

[0044] The ferromagnetic core according to the invention is a stator core of an electric motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Other features and advantages of the invention will become more apparent from the following description by way of example and without limitation, with reference to the attached schematic drawings, in which:

[0046] - Figure 1 is a plan view of a ferromagnetic core for an electric motor according to a possible embodiment of the present invention;

[0047] - Figure 2 Shows the formation Figure 1 A view of the lamination type of the initial layer of the bundle of ferromagnetic cores in a straight line arrangement;

[0048] - Figure 2A , Figure 2B , Figure 2C and Figure 2D Shows Figure 2 Some details of the laminations;

[0049] - Figure 3 Shows the formation Figure 1 A view of the lamination type of the second layer of the bundle of ferromagnetic cores in a straight line arrangement;

[0050] - Figure 3A , Figure 3B , Figure 3C and Figure 3D Shows Figure 3 Some details of the laminations;

[0051] - Figure 4 Shows the formation Figure 1 A view of a lamination type of the middle layer of a bundle of ferromagnetic cores in a straight line arrangement;

[0052] - Figure 5 Shows the formation Figure 1 A view of the penultimate lamination type of the bundle of ferromagnetic cores in a straight line arrangement;

[0053] - Figure 6 Shows the formation Figure 1 A view of the lamination type of the end layer of the bundle of ferromagnetic cores in a straight line arrangement;

[0054] - Fig. 6A , Figure 6B , Figure 6C and Fig.6D Shows Figure 6 Some details of the laminations;

[0055] - Fig. 7A , Figure 7B and Figure 7C yes Figure 1 A bottom plan view of some details of the ferromagnetic core;

[0056] - Fig. 8A , Figure 8B and Figure 8C yes Fig. 7A , Figure 7B and Figure 7C A cross-sectional view of

[0057] - Fig. 9A , Fig. 9B and Fig. 9C yes Figure 1 A top plan view of some details of the ferromagnetic core;

[0058] - Fig. 10A , Fig. 10B and Fig. 10C yes Fig. 9A , Fig. 9B and Fig. 9C A cross-sectional view of

[0059] - Fig.11 A schematic diagram showing the first steps of a process for manufacturing a ferromagnetic core according to the invention in certain stations of a punching / die forming device;

[0060] - Fig.11A , Fig. 11B , Fig. 11C and Fig.11D Shown with Fig.11 some details about the process;

[0061] - Fig.12 A schematic diagram showing some successive steps of a process for manufacturing a ferromagnetic core according to the invention in some stations of a punching / die forming device;

[0062] - Fig. 12A and Fig. 12B Shown with Fig.12 some details about the process;

[0063] - Fig.13A schematic diagram showing some successive steps of a process for manufacturing a ferromagnetic core according to the invention in some stations of a punching / die forming device;

[0064] - Fig.13A , Fig. 13B , Fig. 13C , Fig.13D and Fig.13E Shown with Fig.13 The process is

[0065] Some details about

[0066] - Fig.14 A schematic diagram showing the final steps of a process for manufacturing a ferromagnetic core according to the invention in some stations of a punching / die forming device;

[0067] - Fig.15 is similar to Fig.14 Schematic diagram showing an embodiment of the method according to the present invention in another possible punching / die pressing device;

[0068] - Fig.16 A schematic diagram showing another embodiment of the method according to the present invention; and

[0069] - Figure 17-Figure 20 is a schematic cross-sectional view of other embodiments of the ferromagnetic core according to the present invention. DETAILED DESCRIPTION

[0070] exist Figure 1 FIG. 1 shows a ferromagnetic core 10 manufactured according to the present invention, in particular a ferromagnetic stator core for an electric motor. The ferromagnetic core provides a plurality of laminated segments S1 ... S1 connected together. i ...S N , which can be rotated so as to be able to switch from a closed circular configuration to an open rectilinear configuration and vice versa. N They are simply placed one next to the other at the joint 15 along the ends having complementary shapes.

[0071] Each stacking segment S1...S i ...S N Generally, it has the shape of an arc of a circle, with an inwardly protruding polar expansion 11 and a yoke seat 12 arranged on the outside relative to the central axis C of the ferromagnetic core 10. Each laminated segment S1...S i ...S N The laminations are connected together by crimping portions 13 .

[0072] The embodiment of the ferromagnetic core 10 described herein by way of example provides an initial layer and an end layer of laminations, both of which are provided with pins that engage in corresponding notches in adjacent lamination layers, but it should be understood that the number and arrangement of the pins may also be different, as will be explained below.

[0073] Figure 2 1 shows the structure of the initial layer L1 of the laminations, ie the first layer formed when manufacturing the lamination bundle that will constitute the ferromagnetic core 10. Figure 2A As shown, the laminations of segment S1 have a convex portion 21 at one end of the yoke seat 12 and a concave portion 22 at the other end. Figure 2B In the view of , showing a part of the yoke 12, it can be noted that the lamination of segment S1 has no upwardly or downwardly projecting elements at the bulge 21. The layer L1 constitutes a first auxiliary layer of the lamination.

[0074] like Figure 2C and 2D As shown, the segment S2-S in the initial layer L1 N The remaining laminations instead have an upwardly projecting pin portion 23 at the convex portion 21 , which is obtained by punching out during the blanking / stamping process.

[0075] Furthermore, a cavity 14 is formed in the laminate of the initial layer L1 , which receives and engages with the crimping portion 13 of the laminate of the second layer L2 .

[0076] Figure 3 The structure of the second layer L2 of the laminate is shown. Figure 3A and 3B As shown, segments S1-S N-1 The lamination has a convex portion 31 at one end of the yoke 12 and a concave portion 32 at the other end. N-1 A notch 33 is formed at the convex portion 31 of each laminate, wherein Figure 2C and 2D The stack S2-S of the initial layer L1 shown N The pin portion 23 of the laminate engages in the notch 33. The layer L2 constitutes a second auxiliary layer of the laminate.

[0077] like Figure 3C and 3D As shown, in segment S N The second layer L2 in the stack of sheets, on the other hand, has no notches.

[0078] Furthermore, by punching the laminations of layer L2 a downwardly projecting crimping 13 is obtained which is forced into engagement with the cavities 14 of the laminations of initial layer L1. Furthermore, punching forms cavities 13' in the upper part of the laminations which will be forced into engagement with the crimping 13 of the lamination layer above.

[0079] Figure 4 The middle layer L of the laminate is shown j In all segments S1-S N The middle layer L j The stacking and Figure 3C and 3D The stacks shown are identical.

[0080] Figure 5 The penultimate layer L of the stack is shown M-1 The structure is Figure 3 The structure of the second layer L2 is exactly the same as Figure 3A and 3B Segments S1-S shown N The stacking is the same as Figure 3C and 3D Segment S shown N The laminations are the same. Layer L M-1 Forms the second auxiliary layer of the laminate.

[0081] Figure 5 The end layer L of the laminate is shown M The structure is the last layer formed when manufacturing the lamination bundle that will constitute the ferromagnetic core 10. Fig. 6A As shown, the laminations of segment S1 have a convex portion 41 at one end of the yoke seat 12 and a concave portion 42 at the other end. Figure 6B In the view of FIG. 4 , it can be noted that the laminations of segment S1 have no pins protruding upward or downward at the convex portion 41. Layer L M The first auxiliary layer of the laminate is formed.

[0082] like Figure 6C and 6D As shown, the terminal layer L M Segments S2-S N The remaining laminations instead have a downwardly protruding pin portion 43 at the convex portion 41, which is obtained by punching during the blanking / stamping process.

[0083] In addition, at the end layer L M The crimping portion 13 is formed in all the laminates, and the crimping portion 13 is joined to the second-to-last layer L M-1 In the cavity 13' of the laminate.

[0084] Figures 7A-7C The top view and the corresponding Figures 8A-8C The cross-sectional view shows the segments S1-S in the lower layer constituting the ferromagnetic core 10 at the right end 12D and the left end 12S of the yoke 12. N some details.

[0085] Fig. 7A and8A The end of the segment S1 is shown, in which the convex parts 21 of the initial layer L1 and the concave parts 32 of the second layer L2 and the subsequent intermediate layer L1 are highlighted. j recess 32.

[0086] Figure 7B and 8B Segment S2-S is shown N-1 The end of the yoke 12 is at one end and the rotational coupling of the segments is achieved through this end. The engagement of the pin portion 23 of the initial layer L1 in the notch 33 of the second layer L2 is highlighted in the figure.

[0087] Figure 7C and 8C Segment S is shown N The end portion is at one end of the yoke seat 12, wherein the concave portion 22 of the initial layer L1 and the convex portion 31 of the second layer L2 and the continuous intermediate layer L j The convex portion 31.

[0088] Figures 9A to 9C The top view of the plan and the corresponding Figures 10A to 10C The cross-sectional view shows the segments S1-S in the upper layer of the laminations constituting the ferromagnetic core 10 at the right end 12D and the left end 12S of the yoke 12. N some details.

[0089] Fig. 9A and 10A The end of segment S1 is shown, with the end layer L highlighted. M The convex part 41, the concave part 32 and the penultimate layer L M-1 and the middle layer L below j recess 32.

[0090] Fig. 9B and 10B Segment S2-S is shown N-1 The end portion is at one end of the yoke 12 and the rotational coupling of the segments is achieved through this end portion. The end layer L is highlighted in the figure. M The pin 23 is on the second to last layer L M-1 The notch 33 of the embodiment is engaged.

[0091] Fig. 9C and 10C The segment S at one end of the yoke 12 is shown. N The end portion of which protrudes the end layer L M The concave portion 42 and the penultimate layer L M-1 The convex portion 31 and the intermediate layer L below j The convex portion 31.

[0092] With reference to the various stations of the punching / pressing device, the first step of the process for manufacturing a ferromagnetic core according to the invention is Fig.11 , in which a foil 100 of ferromagnetic material is fed in the direction of arrow F. As is known, a punching / stamping device comprises two separate die halves, at least one of which is movable relative to the other, which die halves usually extend along a series of punching / stamping stations.

[0093] In the first station B1, cavities 101 and 102 are punched out in pairs ( Fig. 11B ), in which position a separating cut is then made to separate the laminations of two adjacent segments. Fig.11A The shape of a portion removed from the foil 100 is shown.

[0094] In the subsequent station B2, a separation cut 103 ( Fig. 11B ) to separate the stacked sheets of adjacent segments. Station B2 can be in operation or inoperation, because the separation cut 103 only acts on the initial layer L1 and the terminal layer L M on the stack. Fig. 11C is a cross-sectional view of one of the punching / die devices in the cutout 103, in which it can be noted the actuated punch P1 and the extractor E1 in the upper die half of the punching / die device and the actuated punch P2 and the extractor E2 in the lower die half.

[0095] Segment S1-S of the second layer L2 N-1 Notch 33 and the second to last layer L M-1 Segments S1-S N-1 The notches 33 are punched in station B3, so the punch forming the notches 33 can be selectively actuated in station B3. However, portions of the foil 100 are punched to define the segments S1-S N The punch is always actuated in the same station B3. The shape of the portion removed to form the notch 33 is Fig.11D The same station B3 is shown in a larger scale, and the dashed line portion in the same station B3 represents the removed limiting segments S1-S N Section 107 of .

[0096] Therefore, the foil 100 is Fig.12 Station B4 is a standby station in which no punching or coining operations are performed, to allow selective actuation of the punch of the subsequent station B5.

[0097] In the subsequent station B5, a separation cut 104 is formed ( Fig. 12A ) to separate the stacks of adjacent segments. Station B5 can be in operation or inoperation, because starting from the second layer L2, then passing through the middle layer L j Extends all the way to the penultimate floor LM-1 , the separation cut 104 acts on the laminate S1-S N superior. Fig. 12B is a cross-sectional view of one of the punching / die units in the cutout 104, in which it can be noted the actuated punch P3 and the extractor E3 in the upper die half of the punching / die unit and the actuated punch P4 and the extractor E4 in the lower die half.

[0098] Like station B4, station B6 is also a standby station in which no punching or coining operations are performed, to allow selective actuation of the punches of subsequent stations.

[0099] Foil 100 in Fig.13 The workstations B7-B9 shown in FIG.

[0100] In the station B7 , the cavities 14 of the laminations of the single initial layer L1 are punched out, wherein the crimps 13 of the laminations of the second layer L2 are forced into engagement with the cavities 14 . Fig.13A The shape of the blanked parts is shown. The punches that perform these blanking operations are therefore active only on the laminations of the first layer L1, which will therefore constitute a separation layer for separating the ferromagnetic cores that are pushed into the accumulation chambers of the blanking dies of the blanking / stamping device in the final part of the process.

[0101] The central disk 108 of the lamination 100 is also punched out in the same station B7 in order to define the end of the polar extension 11 of the ferromagnetic core. The punch that performs this punching is therefore always in operation.

[0102] Segment S2-S N The pin portion 23 of the first layer L1 of the laminate ( Fig. 13B ) or segments S2-S N The last layer of the stack L M The pin portion 43 ( Fig. 13C ) is optionally pressed in station B8. Station B8 is thus actuatable, deactuable or replaceable.

[0103] Layer L2-L is punched out in station B9 M All stacks S1-S N The crimping portion 13 ( Fig.13D and 13E ).like Fig.13E As shown, a cavity 13' is formed by stamping the crimping portion 13, into which the crimping portion of the upper laminate will be forced to engage. In any case, since the cavity 14 only needs to be formed in the first layer L1 of the laminate, the station B9 also includes an actuable and retractable punch.

[0104] Fig.14The final step of the process for manufacturing a ferromagnetic core according to the invention is shown. Each layer of the laminate 110 is punched out of a foil 100 in station B10 and pushed into an accumulation chamber below the die of station B10. This allows the crimp 13 to be coupled by interference to the cavity 14 of the first layer L1 or to the cavity 13' of the subsequent laminate, thus forming a complete ferromagnetic core, for example in Figure 1 The ferromagnetic core is represented by 10.

[0105] For example, a cutter 111 can be provided in the station B11 , which allows the waste of foil 100 to be reduced to small-sized pieces 115 .

[0106] Fig.15 Another embodiment of the method according to the invention is shown. In each blanking step of the laminate layer 110, the accumulation chamber below the die of the station B10' can be rotated by a predetermined angle (arrow R). As is known, this allows to compensate for the lateral thickness differences that often occur between the two sides of the foil 100.

[0107] The rotation angle depends on the number N of segments forming the ferromagnetic core 10 and is an appropriate fraction (one-N) of the circumference. For example, in the embodiment described herein, in which the ferromagnetic core 10 is composed of twelve segments, the rotation angle applied to the accumulation chamber can be as small as 30°, i.e., 2π / N, but can also be 60° (2π*2 / N), 90° (2π*3 / N), etc., so that each segment of the punched lamination 110 is correctly coupled and accumulated with each segment of the lamination located directly below the accumulation chamber.

[0108] The rotational movement of the accumulation chamber in station B10', in which the final punching out of each layer of the stack 110 takes place, can be imposed, for example, by an electric motor (not shown) which transmits the rotational movement to the pulley 120 via a toothed belt 130, or by any transmission system capable of ensuring the necessary precision positioning of the accumulation chamber in station B10'.

[0109] Fig.16 An embodiment of the method according to the invention is schematically shown, in which the foil 100 is punched along two rows of staggered stations with identical punching / stamping devices. This embodiment can be adopted, for example, because of productivity, while limiting the waste obtained as machining residues of the foil 100. The punching of the foil 100 can anyway also be carried out along more rows on the same foil 100, i.e. along three or more rows, using punching, punching and / or stamping stations of the punching / stamping devices positioned appropriately staggered along adjacent rows, in order to limit waste as much as possible.

[0110] Figures 17 to 20 Further embodiments of ferromagnetic cores according to the invention are shown.

[0111] For example, Fig.17 The ferromagnetic core 50 shown may comprise only one first auxiliary layer of the laminate and one second auxiliary layer of the laminate, the first auxiliary layer corresponding to the end layer L of the ferromagnetic core 10 described so far. M , the second auxiliary layer corresponds to layer L M-1 The initial layer L1' can be manufactured similar to the initial layer L1 but without the pin portion 23, while the intermediate layer L j The same as the middle layer of the ferromagnetic core 10 .

[0112] In the same way, Fig.18 The ferromagnetic core 60 shown may comprise only one first auxiliary layer of the lamination corresponding to the initial layer L1 of the ferromagnetic core 10 and only one second auxiliary layer of the lamination corresponding to the layer L2. M Similar but without the end layer L of the pin portion 43 M ', while the middle layer L j The same as the middle layer of the ferromagnetic core 10 .

[0113] However, Fig.19 The ferromagnetic core 70 includes a first auxiliary layer L j ' and the second auxiliary layer L j ", the first auxiliary layer L j ' and the second auxiliary layer L j " as the middle layer of the lamination bundle forming the ferromagnetic core. In this embodiment, the initial layer L1' of the lamination is Fig.17 The initial layers of the ferromagnetic core 50 are identical, while the final layers LM' of the laminations are identical to Fig.18 The end layers of the ferromagnetic core 60 are the same.

[0114] Fig. 20 The ferromagnetic core 80 shown is similar to Fig.19 The ferromagnetic core, in which the auxiliary layer L j ' and L j "In an inverted position.

[0115] Various modifications may be made to the embodiments described herein by way of example without departing from the scope of the present invention. For example, the number of first auxiliary layers and the corresponding number of second auxiliary layers in the ferromagnetic core may also differ from what has been described so far, for example by combining various embodiments of the ferromagnetic cores 10, 50, 60, 70 and 80.

Claims

1. A method for manufacturing a ferromagnetic core (10) for an electric motor, the ferromagnetic core comprising a plurality of laminated segments (S1-S2) N ), the plurality of stacked segments are composed of bundled stacked sheets, the plurality of stacked segments (S1-S N ) When punching each layer of laminated sheets (L1-L M ) are connected together in a closed circular configuration to form a complete ferromagnetic core in a circular configuration and connected together with the possibility of rotation so as to be able to switch from the closed circular configuration to an open linear configuration, and vice versa, wherein each of the plurality of stacked segments (S1-S N ) has an arc shape, has an inwardly protruding polarity expansion portion (11) and a yoke seat (12) arranged on the outside relative to the central axis of the ferromagnetic core (10), wherein the laminated sheets of each of the plurality of laminated segments are connected together by a crimping portion (13), and wherein each of the plurality of laminated segments (S1-S N ) is connected to adjacent stacking segments along the yoke (12) with the possibility of reciprocating rotation, the method comprising the following steps: a) feeding a ferromagnetic material foil (100) along a punching station and a die-stamping station of a punching / die-stamping device; b) forming one or more crimping portions (13) and corresponding cavities (13', 14) by punching at the lamination sheets of each of the plurality of lamination segments; c) punching out an initial layer (L) of the laminate in the closed circular configuration of the ferromagnetic core (10); i ) and push it into the accumulation chamber of the blanking die of the blanking / pressing die device; d) punching out a plurality of intermediate layers (L) of the laminate in the closed circular configuration of the ferromagnetic core (10) j ), and by placing each intermediate layer (L j ) is coupled with the corresponding cavity (13', 14) of the next layer of the laminated sheet layer to form each intermediate layer (L) to be punched out in the accumulation chamber of the punching die. j ) stacked on the next layer of laminated sheets; e) punching out an end layer of the laminate in the closed circular configuration of the ferromagnetic core (10) and pushing it into the accumulation chamber of the punching die by coupling the protruding crimping portion (13) of the end layer of the laminate with the corresponding cavity (13', 14) of the next laminate layer; wherein each of the plurality of stacked segments (S1-S2) arranged in a closed circular configuration N ) are formed by the laminated sheets, the laminated sheets having a recess (22, 32, 42) at one end of the yoke seat (12) of each laminated segment, and a protrusion (21, 31, 41) at the other end of the yoke seat (12) of each laminated segment, the recess (22, 32, 42) and the protrusion (21, 31, 41) having complementary shapes and sizes, It is characterized in that it comprises the following steps: f) at least one first auxiliary layer (L j ') in the vicinity of the protrusion of the yoke seat (12) at one end of the laminated sheet, wherein the laminated sheet forms each of the plurality of laminated segments (S1-S N ); g) further in the first auxiliary layer (L j ') in the end blanking recess (22, 32, 42) of the laminated sheet opposite to the yoke seat (12), wherein the laminated sheet forms each of the plurality of laminated segments (S1-S N );as well as h) at least one second auxiliary layer (L j ") is punched out near a convex portion of one end of the yoke seat (12) of the laminate, wherein the laminate forms each of the plurality of laminate segments (S1-S N ), Wherein, the first auxiliary layer (L j ') and the second auxiliary layer (L j ") is a continuous layer in a bundle of laminated sheets, the bundle of laminated sheets forming each of the plurality of laminated segments (S1-S2) of the ferromagnetic core N ), and wherein the first auxiliary layer (L j ') of the pin portion and the second auxiliary layer (L j ") is engaged with the opening.

2. The method according to claim 1, characterized in that In the second auxiliary layer (L j The opening formed in the casing consists of a notch (33).

3. The method according to claim 1, characterized in that The first auxiliary layer (L j ') and the second auxiliary layer (L j ") is arranged between the middle layers of the laminated sheets of the ferromagnetic core (10), the ferromagnetic core being composed of the plurality of laminated segments (S1-S2) arranged in a closed circular configuration N )constitute.

4. The method according to claim 1, characterized in that In the ferromagnetic core (10), the first auxiliary layer (L j ') is arranged as the initial layer, and the second auxiliary layer (L j ”) is coupled to an intermediate layer of the stacked sheets directly above it, wherein the ferromagnetic core is composed of the plurality of stacked segments (S1-S2) arranged in a closed circular configuration N )constitute.

5. The method according to claim 1, characterized in that In the ferromagnetic core (10, 110), the first auxiliary layer (L j ') is arranged as the end layer of the laminate, and the second auxiliary layer (L j ") is coupled to an intermediate layer of the laminated sheet directly below it, wherein the ferromagnetic core is composed of the plurality of laminated segments (S1-S2) arranged in a closed circular configuration. N )constitute.

6. The method according to claim 1, characterized in that A plurality of first auxiliary layers coupled to a corresponding number of second auxiliary layers are formed, wherein each of the first auxiliary layers and each of the second auxiliary layers is coupled to one of the intermediate layers of the stack, or to the initial layer of the stack, or to the terminal layer of the stack.

7. The method according to claim 1, characterized in that The ferromagnetic core (10) is the stator core of an electric motor.

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