Apparatus and methods for manufacturing lamellar packs for electric motors for automotive applications

Abstract

An apparatus (1) for manufacturing lamellar packs (100) for electric motors for automotive applications comprises a cutting system (2), cutting lamination segments (111) with the shape of annular sectors out of a lamination sheet (200). The lamination segments (111) are sequentially received in a stacking support (4), which is rotated between receiving the lamination segments (111), such that the lamination segments (111) are laid adjacent to each other to form a lamination layer (110) of the lamellar pack (100), while leaving a gap between adjacent segments (11). The stacking support (4) is preferably rotated also before starting new layers (110), such as to arrange the lamination segments (111) in a helical fashion.

Description

[0001] Title: “Apparatus and methods for manufacturing lamellar packs for electric motors for automotive applications”

[0002] DESCRIPTION

[0003] Field of the invention

[0004] The present invention relates to the field of electric motors for automotive applications. In particular, the present invention relates to an apparatus and a method for manufacturing a lamellar pack for such a motor.

[0005] Background of the invention

[0006] Electric motors are well-known to comprise a stator, with a central cavity, and a rotor arranged in the stator cavity and connected to a rotation shaft. The stator and the rotor are usually made of ferromagnetic materials, to guide a magnetic field generated by currents in stator and / or rotor windings.

[0007] In order to reduce power losses, the stator and / or the rotor can be formed as a lamellar pack comprising lamination layers stacked on each other.

[0008] The shape of the lamination layers may vary depending on the motor to be manufactured, and in particular depending on the number and arrangement of the slots for housing the conductive windings. It is known to die-cut each lamination layer of the desired shape out of a lamination sheet. Usually, in order to save as much scrap material as possible from the lamination sheet, a lamination layer of the stator and a lamination layer of the rotor are die-cut simultaneously and concentrically out of the same lamination sheet.

[0009] Then, the lamination layers must be stacked upon each other with the highest possible precision, especially as regards the central hole of the layer and the slots.

[0010] Prior art documents JP5347321, US8127429, US8850937 and US9178403 show examples of lamellar packs, where each lamination layer is not monolithic, but is formed of a plurality of lamination segments. The lamination segments are cut by punches and matrixes with sharp edges, with the shape of annular sectors, and are arranged in side contact to form the lamination layers. The stacking of the segment is obtained by rotating a support upon which the segments are laid.

[0011] Drawback of the prior art

[0012] The applicant noted that, as the punches and matrixes keep cutting the segments, their edges wear, and thus the size of the segments has a slight progressive increase.

[0013] In view of the varying size, it is difficult to put the segments in the correct position, such that their lateral sides are not in contact or overlapping. In any case, the segments are usually pressed to fit their positions, and this causes a high mechanical stress at the lateral sides of the segments. However, the applicant noted that this mechanical stress reduces the magnetic performances of the lamination segments.

[0014] Summary of the invention

[0015] An object of the present invention is to increase the magnetic performance of the lamination segments. This and other objects are achieved by an apparatus and a method for manufacturing lamellar packs for electric motors for automotive applications, according to any one of the appended claims.

[0016] According to the invention, the cutting system is configured to cut the lamination segments with respective angular widths, selected such that, while laying sectors adjacent to each other to form a layer, a gap is left between adjacent lamination segments. Namely, the angular width of the last placed segment is set smaller than the span angle by which the subsequent lamination segment is rotated.

[0017] Advantageously, with a proper dimensioning of the gap, the segments will never be in contact despite their size increase. Thus, there is no local compression at the lateral sides of the segments, and their magnetic performance is not reduced. The applicant performed tests to compare the magnetic performance of a segment which was compressed at the lateral sides and a segment without such compression, and found that, by avoiding compression, the performance is usually increased by more or less 50%.

[0018] The gaps in any case should be kept as small as possible, for example between 25 pm and 75 pm, because in use each gap creates a local concentration of magnetic field.

[0019] Thus, in preferred embodiments, upon completion of the layer, a further rotation is performed by a stagger angle, to avoid that the gaps of successive layers are vertically aligned.

[0020] Advantageously, the interface effects between the segments affecting the electromagnetic field are distributed in different angular positions between different layers, and so they are not concentrated. Brief description of the drawings

[0021] The present invention will now be described in more detail hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown.

[0022] FIG. 1 is a top view of a lamellar pack for an electric motor obtainable by the apparatus and method of the invention,

[0023] FIG. 2 is a perspective view of the lamellar pack of FIG. 1,

[0024] FIG. 3 is a side view of an apparatus for manufacturing lamellar packs according to one embodiment of the invention,

[0025] FIG. 4 is a top view of a lamination sheet being cut by the apparatus of FIG. 3 to obtain lamination segments therefrom,

[0026] FIG. 5 is a perspective view of stacking support and a main matrix of the apparatus of FIG. 3,

[0027] FIG. 6-8 are side views of cutting steps of a lamination sheet by the apparatus of FIG. 3, where gaps between lamination segments have been omitted,

[0028] FIG. 9 is a side view of the removal of a completed lamellar pack from the apparatus of FIG. 3.

[0029] Detailed description

[0030] A lamellar pack to be manufactured with the apparatus and method of the invention is designated with reference number 100 and is shown in figures 1 and 2. The lamellar pack 100, when completed, includes a plurality of lamination layers 110 made of a ferromagnetic material, which are stacked on top of each other in an axial direction Z- Z, that is the direction of a central axis. Only some of the lamination layers 110 of the lamellar pack 100 are shown in the drawings, for the sake of simplicity.

[0031] During manufacturing with the described apparatus and method, the axial direction Z-Z will be preferably substantially vertical. However, after manufacturing, the lamellar pack 100 can be rotated and the axial direction Z-Z may assume any spatial orientation.

[0032] Two end lamination layers 110 are spaced from each other in the axial direction Z-Z and define two opposite end faces 101 of the lamellar pack 100. The remaining lamination layers 110 are arranged between the end lamination layers 110. As described below, the manufacturing process starts from a start layer and ends with a final layer, respectively defining the end faces 101.

[0033] The lamellar pack 100 has an outer side surface 102 connecting the end faces 101. In preferred embodiments, the outer surface 102 has a cylindrical main portion, centered on the central axis.

[0034] The lamellar pack 100 preferably has a central through channel 120 extending up to the end faces 101. Thus, the lamination layers 110 preferably have an annular shape. An inner surface 103 of the lamellar pack 100 faces the channel 120. In case of a stator, the channel 120 may be designed to house a rotor. In case of a rotor, the channel may be designed to house a shaft. In preferred embodiments, the inner surface 103 has a cylindrical main portion centered on the central axis.

[0035] Preferably, the lamellar pack 100 has a number of through slots 130 extending up to the end faces 101. The through slots 130 may be designed to house conductive windings and / or permanent magnets (not shown). The through slots 130 are spaced to each other in a circumferential direction around the central axis. The through slots 130 may be open to the outer surface 102, or to the inner surface 103, or may be fully encircled by material of the lamellar pack 100.

[0036] In the following, reference will be made not only to a completed lamellar pack 100, but also to a lamellar pack 100 being formed, with reference to figures 3 and 6-8. In particular, in a first stage no lamination layer 110 has already been completed, and a first, end lamination layer 110 (the start layer) is being formed. In other stages, one or more lamination layers 110 have been completed, in a lesser number than the layers 110 of the complete pack 100. In still further stages, a number of lamination layers 110 have been completed, and a further lamination layer 110 is being formed on top of them. In the drawings, for the sake of simplicity only some lamination layers 110 of the pack 100 have been represented.

[0037] During all these stages, a skilled person will in any case recognize, in the lamellar pack 100 being formed, a bottom surface, on an underside of the first lamination layer 110 formed or being formed, and a top surface, on the upper side of the last lamination layer 110 formed or being formed. The top surface of the lamellar pack 100 being formed is not necessarily the final layer of the finished lamellar pack 100.

[0038] The apparatus 1 for manufacturing the lamellar pack 100, shown in figure 3, comprises a cutting system 2, configured to cut lamination segments 111 out of a lamination sheet 200. Plural lamination segments 111, which may be identical to or different from each other, may be cut out of the same lamination sheet 200.

[0039] In particular, the cutting system 2 is configured to cut the lamination sheet 200 in one or more steps along a predetermined contour line enclosing the lamination segment 111, such that the lamination segment 111 has a desired predetermined shape. The shape of each lamination segment 111 has a respective angular width, to define an annular sector of a layer 110 of the lamellar pack 100. Preferably, the angular width is the same for all the lamination segments 111.

[0040] In particular, the shape of the lamination segment 111 is designed such that a lamination layer 110 can be composed by a predetermined layer number of lamination segments 111, arranged side by side along the circumferential direction around the central axis. In the following, the term “layer group” will be used to designate a group including the layer number of lamination segments 111, intended to be positioned so as to form together one lamination layer 110.

[0041] Thus, the predetermined angular width is preferably substantially a submultiple of 360°, such as 60° or 45°, in which case the layer number of lamination segments 111 is, respectively, six or eight. As described below, the angular width may be a little smaller, but this reduction in width can be even smaller than 1°. The angular width is measured in the circumferential direction around the central axis.

[0042] In more detail, each lamination segment 111 has two lateral sides 112, designed to face adjacent lamination segments 111. Each lamination segment 111 further has an inner side 113 and an outer side 114, forming, together with the lateral sides 112, a main outline of the lamination segment 111. Preferably, the inner side 113 and the outer side 114 have respective arc-shaped main portions. The angular width can be measured between the lateral sides 112, or between end portions of either the inner side 113 or the outer side 114.

[0043] In the following, the term contour line will be used to designate the exact contour of the shape of a lamination segment 111. Instead, the term main outline may have the same meaning as the contour line, in case the shape is simple, or may designate a closed line enveloping the shape, which is more simplified than the contour line.

[0044] In fact, in view of the presence of slots 130 or other optional features known to the skilled person, such as positioning ears, the main outline of the predetermined shape may be substantially an annular sector, while some details of the contour line may depart from it.

[0045] In particular, the main outline may be intended as the shape of the closed line along which the lamination segment 111 is cut by the main matrix and the main punch described below.

[0046] In some embodiments, the lateral sides 112 may be shaped as straight segments extending radially away from the central axis. In other embodiments, the lateral sides 112 may be inclined to the radial direction, and / or may be curved, and / or may include corners. In general, lateral sides 112, facing each other and belonging to two adjacent lamination segments 112, have complementary shapes. For example, one may include a recess and the other may include a protrusion. These recesses and protrusions should not be taken in account when measuring the angular width.

[0047] However, according to one aspect of the invention, a gap 116 is left between each couple of adjacent lamination segments 111 of at least one lamination layer 110, preferably of a plurality of lamination layers 110, more preferably of all the lamination layers 110. Therefore, in case of straight lateral sides 112, they are not in contact with each other, and they are preferably parallel. Also, in case of non-straight lateral sides 112, they are not in contact with each other, but they are spaced by a gap 116, preferably having substantially constant width.

[0048] It is to be noted that a gap 116 with a small width can be enough for the purposes of the invention. For example, while a lamination segment 111 may have a width of some tens of cm in the circumferential direction, the gap 116 may have a width smaller than 1 mm in the circumferential direction, such as some tens of microns, in the preferred examples between 25 pm and 75 pm. In general, the gap width is preferably lower than 5% the segment width.

[0049] In fact, as the applicant noted, higher magnetic performances are obtained by not compressing the lateral sides 112 of the lamination segments 111, that is by introducing the gap 116 such that there is no contact between adjacent segments 111. Therefore, the gap 116 can be made as small as possible, depending on the accuracy of the apparatus 1 of the invention, as long as there is no contact.

[0050] It is to be noted that, despite the adjacent lamination segments 111 are not in contact to each other, they can be held in position by adhesion to common lamination segments 111 of other layers 110, as will be apparent below.

[0051] The apparatus 1 preferably comprises a lamination supply system 3, shown in figure 3, defining a lamination path 31 for sliding the lamination sheet 200. The lamination supply system 3 includes a lamination feeder 32, configured to feed and move the lamination sheet 200 along the lamination path 31. In the preferred embodiment, the lamination feeder 32 comprises a lamination roll and a motor for unwinding the lamination sheet 200 from the lamination roll. Preferably, the lamination sheet 200 is advanced by discrete steps, in order to let the cutting system 2, as well as any other automated component, sequentially perform their operations for each lamination segment 111, already formed or still being formed.

[0052] The apparatus 1 comprises a stacking support 4, where the lamination segments 111 are assembled into lamination layers 110 and into the lamellar pack 100.

[0053] In the following, embodiments of the invention will be described in detail, where the lamination segments 111 are continuously received in the stacking support 4 in the same order as they are cut by the cutting system 2. However, further embodiments can be provided, where the lamination segments 111 are temporarily stored after being cut, and are supplied to the stacking support 4 thereafter, possibly in a different order compared to the order of cutting.

[0054] In the preferred embodiments, the cutting system 2 and the stacking support 4 are arranged along the same lamination path 31. In more detail, the stacking support 4 is preferably arranged below the lamination path 31.

[0055] The stacking support 4 is configured to sequentially receive and to sustain the lamination segments 111.

[0056] Preferably, the stacking support 4 comprises a support surface 41 for sustaining the lamination segments 111, and a perimetral wall 42 surrounding the support surface 41. In the following, rotational and axial movements of the stacking support 4 will be described. It is to be noted that, in various embodiments, these rotational and axial movements may be performed by both the support surface 41 and the perimetral wall 42 together, or by only one of these two, provided that they result in the desired movement of the lamination segments 111.

[0057] The cutting system 2 comprises a main matrix 21 and a main punch 22. The main matrix 21 is arranged above the stacking support 4, as best visible in figures 5 and 9. In particular, the main matrix 21 may define a portion of the lamination path 31, to support the lamination sheet 200. Thus, the lamination feeder 32 is configured to slide the lamination sheet 200 over the main matrix 21. In figure 5, some components below the lamination path 31 are represented in dashed lines, as not being visible.

[0058] The main matrix 21 has a hole 23 with a cutting edge matching the main outline of the predetermined shape of the lamination segments 111.

[0059] The main punch 22 is arranged above the lamination path 31 and is movable transverse to the lamination path 31, in particular along the axial direction Z-Z, as shown in the sequence of figures 6-8. The main punch 22 has an abutting surface with a cutting outer edge matching the main outline of the predetermined shape of the lamination segments 111. Optionally, the main punch 22 may be mounted to an annular structure 26 matching the shape of a whole lamination layer 110. Thus, the main punch 22 occupies an annular sector of the annular structure 26. In any case, only the main punch 22 is designed to perform a cutting operation, while the remainder of the annular structure 26 may be considered a fake punch. The main punch 22 is configured to push down a region of the lamination sheet 200, which is above the hole 23 of the main matrix 21. Thus, such region is deformed downward through the hole 23, while the surrounding region of the lamination sheet 200 is supported by the cutting edge of the main matrix 21. This causes the lamination sheet 200 to be cut along a line matching the shapes of the outer edge of the main punch 22 and the cutting edge of the main matrix 21, that is the main outline of a lamination segment 111. Accordingly, the lamination segment 111 is cut out of the lamination sheet 200, and is pushed by the main punch 22 through the hole 23 of the main matrix 21, directly in the stacking support 4.

[0060] Figure 6 shows the position of the main punch 22 before cutting, figure 7 shows the main punch 22 during cutting, while a new lamination segment 111 is pressed on the lamellar pack 100 being formed, and figure 8 shows the main punch 22 raised after the cutting operation.

[0061] It is to be noted that, as already known in the art, in order to achieve the cutting along the desired line, the hole 23 of the main matrix 21 should be larger than the main punch 21 by a small clearance. Preferably, the lamination sheet 200 reaches the stacking support 4 without the lamination segment 111 having been already precut along substantially the whole main outline, and so substantially the whole main outline is cut by the main punch 22 and main matrix 21.

[0062] While the main outline of the lamination segment 111 is obtained by cutting at the main matrix 21 and the main punch 22, a lamination segment 111 may require additional cuts that should not be formed in the same step as the main outline, in order to obtain the final contour line. Preferably, these additional cuts may overlap only minor portions of the main outline, preferably less than 20% of the main outline.

[0063] In this case, the cutting system 2 may comprise one or more auxiliary matrixes 24 and one or more auxiliary punches 25. In a similar manner as described for the main matrix 21 and the main punch 22, each auxiliary punch 25 is configured to cooperate with a respective auxiliary matrix 24 to cut out a portion of the lamination sheet 400. Thus, each auxiliary matrix 24 is configured to support the lamination sheet 200 and has a hole with the shape of a region of the support sheet 200 to be removed. The respective auxiliary punch 25 has the same shape and is configured to push the portion to be removed through the hole of the auxiliary matrix 24.

[0064] However, differently from the main matrix 21, any auxiliary matrix 24 is not arranged above the stacking support 4, but is arranged upstream the main matrix 21, according to the sliding direction of the lamination sheet 200.

[0065] In this manner, details of the lamination segments 111 can be formed by cutting, before the main outline of each lamination segment 111 is formed.

[0066] Figure 4 shows the lamination sheet 200 being progressively cut while advancing along the lamination path 31. Thus, from the left to the right, new cuts performed by successive punches accumulate with the cuts already performed. In this drawing, the auxiliary and main punches 25, 22 are only conceptually shown, and the skilled person will understand that they are not arranged aside the sheet 200 as shown, but above the sheet 200. The same applies for the adhesive dispenser 5 of figure 4.

[0067] A first group of auxiliary punches 25 and matrixes 24 are configured to cut reference holes 201 in the lamination sheet 200, for the purpose of precise positioning of the lamination sheet 200 in the following steps.

[0068] Then, another group of auxiliary punches 25 and matrixes 24, downstream the first group, is configured to cut a first number of slot openings 115 from the lamination sheet 200. Still another group of auxiliary punches 25 and matrixes 24, downstream the second one, is configured to cut a second number of slot openings 115 from the lamination sheet 200, interleaved with the previously formed slot openings 115.

[0069] The slot openings 115 are intended to define the through slots 130 of the lamellar pack 100, after the lamination segments 111 have been assembled. Upon cutting the lamination sheet 200 by the main matrix 21 and the main punch 22, the slot openings 115 are at least partially internal to the main outline of the shape of the lamination segment 111.

[0070] In the view of the lamination sheet 200 being cut, downstream the main punch 22 further cuts remain visible, for the lamination segments 111 cut in the previous cycles. It can be appreciated that only a little scrap material remains on the right.

[0071] In some embodiments, one or more auxiliary matrixes 24 and punches 25 may be configured to perform different cuts for successive lamination segments 111. In one example, a different arrangement or number of slot openings 115 may be formed in distinct lamination segments 111, by different auxiliary matrixes 24 and punches 25, or by the same auxiliary matrixes 24 and punches 25 moving in different positions.

[0072] In another example, one or more auxiliary matrixes 24 and punches 25 may be configured to remove a side portion of a lamination segment 111 to be cut, such that the angular width of the lamination segment 111 is reduced compared to other lamination segments 111 for which this removal is not performed.

[0073] The apparatus 1 further comprises an adhesive dispenser 5, configured to apply an adhesive for bonding the lamination segments 111 to each other. Thus, lamination segments 111 sequentially received in the stacking support 4 may adhere to previous lamination segments 111 already laying in the stacking support 4.

[0074] In the preferred embodiment, the adhesive dispenser 5 is arranged upstream the stacking support 4, and upstream the main matrix 21 and the main punch 22. Optionally, the adhesive dispenser 5 may be arranged downstream one or more auxiliary matrixes 24 and auxiliary punches 25.

[0075] Therefore, the adhesive may be applied before the lamination segment 111 receiving the adhesive has been cut out of the lamination sheet 200 along its main outline. In particular, the adhesive is applied upon a region of the lamination sheet 200 corresponding to a lamination segment 111, that is a region intended to be successively cut as a lamination segment 111. In other embodiments, the adhesive is directly applied upon the lamination segments 111 which have been already cut from the lamination sheet 200.

[0076] In preferred examples, the adhesive dispenser 5 may include one or more rolls, configured to spread adhesive on a region of the lamination sheet 200, and / or it may include one or more nozzles, configured to place adhesive in the form of one or more predetermined glue dots on the lamination sheet 200.

[0077] In one aspect of the invention, the apparatus 1 comprises rotation means 6, configured to rotate the stacking support 4 about a rotation axis, that is the central axis of the lamellar pack 100, and extends in the axial direction Z-Z.

[0078] Moreover, the apparatus 1 preferably comprises a height regulation system 7, configured to move the lamellar pack 100 in the stacking support 4 in the axial direction Z-Z.

[0079] In the preferred embodiment, the rotation means 6 are connected to the perimetral wall 42 in order to rotate the perimetral wall 42. Moreover, the support surface 41 is rotationally constrained to the perimetral wall 42, in other to rotate jointly with the perimetral wall 42. Additionally, the height regulation system 7 is connected to the support surface 41, in order to axially move the support surface 41. Instead, the perimetral wall 42 is fixed in the axial direction Z-Z, and the support surface 41 is slidable along the perimetral wall 42.

[0080] In another embodiment, the support surface 41 moving along the axial direction Z-Z is not rotatable around the rotation axis. In this case, the rotating perimetral wall 42 should nevertheless be configured to rotate the lamination segments 111 inside the stacking support 4 around the rotation axis. In this embodiment, as the rotation means are supposed to rotate the stacking support 4, the support surface 41 may be considered not to belong to the stacking support 4, but just to be another component of the apparatus 1.

[0081] In still another embodiment, the rotation means 6 may be connected to the support surface 41, in order to rotate the support surface 41. Instead, the perimetral wall 42 may be rotationally fixed. The height regulation system 7 is still intended to axially move the support surface 41. In this embodiment, the perimetral wall 42 may be considered not to belong to the stacking support 4, as they don’t rotate, but just to be another part of the apparatus 1.

[0082] A skilled person may envisage several possible designs of the rotation means 6 and of the height regulation system 7. In one embodiment, the rotation means 6 include a motor and a pulley, preferably connected to the perimetral wall 42. In one embodiment, the height regulation system 7 includes an axially movable piston, preferably arranged below the support surface 41.

[0083] The apparatus 1 comprises a control unit (not shown), configured to control at least the rotation means 6. Preferably, the same control unit is further configured to control the height regulation system 7, and / or the lamination supply system 3, and / or the cutting system 2.

[0084] The control unit is configured to monitor a progression stage of the manufacture of the lamellar pack 100. Preferably, for this purpose, the control unit is configured to count the number of lamination segments 111 being cut and received in the stacking support 4. The number of lamination segments 111 can be used to determine how many lamination layers 110 of the lamellar pack 100 have already been completed, and how many lamination segments 111 have already been arranged in the current top layer. Therefore, the correct positioning for the successive lamination segment 111 can be determined.

[0085] In general, the control unit will control the rotation means 6 to rotate the stacking support 4, and so the lamellar pack 100 being formed therein, by specific angles between the receipt on the stacking support 4 of two successive lamination segments 111. In other words, the control unit is configured to alternate one cutting operation of the cutting system 2, to obtain one lamination segment 111 that is received on the stacking support 4, and (in most cases) one rotation of the stacking support 4 by the rotation means 6, to prepare the stacking support 4 for receiving the next lamination segment 111 in the desired position.

[0086] At substantially the same time when the stacking support 4 is rotated, that is between two successive cutting operations, the control unit also controls the lamination feeder 32 to feed a predetermined length of the lamination sheet 200, such that the lamination sheet 200 slides along the lamination path 31 by this length and the lamination sheet 200 is ready for the subsequent cutting operation.

[0087] It is to be noted that, in view of the lamination segments 111 being cut as sectors, they may be cut from portions of the lamination sheet 200 very close to each other along the sliding direction of the lamination sheet 200, and few scrap material is left.

[0088] Based on the progression of the manufacture of the lamellar pack 100, the control unit may control the rotation means 6 in different manners. In particular, the very first lamination segment of the first layer 110 of the lamellar pack 100 being formed can be placed substantially wherever desired. Then, a different control may be required for:

[0089] - a stage in which the top layer 110 of the lamellar pack 100 being formed is incomplete, meaning that it already includes at least one lamination segment 111, but it still lacks at least one lamination segment 111, and

[0090] - a stage in which the top layer 110 of the lamellar pack 100 being formed has been completed, and another lamination segment 111 is to be received in the stacking support 4 as a first lamination segment 111 of a successive layer, becoming the new top layer over the completed layer. Of course, upon completion of the final layer 110 the process may just stop, with no more rotations needed.

[0091] As described above, one lamination layer 110 is formed by a layer group including the layer number of lamination segments 111, which are received in sequence. While the formation of the top lamination layer 110 is in progress, meaning that the lamination segments 111 of one layer group are being received in sequence, between the receipt on the stacking support 4 of successive lamination segments 111 of the layer group, the control unit is configured to control the rotation means 6 to rotate the stacking support 4 by a span angle.

[0092] In general, the span angle is selected by the control unit such that the lamination segments 111 of the layer group are received adjacent to each other to form together one lamination layer 110 of the lamellar pack 100, covering an overall width angle of 360°.

[0093] However, according to one aspect of the invention, upon receiving the segments 111 in the stacking support 4, a gap 116 is left between each couple of adjacent lamination segments 111 of the lamination layer 110. Thus, the lamination layer 110 is interrupted at each gap 116, and is divided in plural parts. In other words, adjacent lamination segments 111 are not in tough with each other, but are spaced from each other. In more detail, the span angle is selected such that, for each couple of adjacent lamination segments 111, two lateral sides 112 of respective lamination segments 111 face each other, but are not in contact with each other.

[0094] In order to obtain the gap 116, the cutting system 2 is set to cut the lamination segments 111 with appropriate angular widths. In particular, the angular width of a lamination segment 111 of a layer 110 being formed is set to be smaller than the span angle set for rotation of the stacking support 4 after receiving the lamination segment 111. The difference of this span angle to this angular width is a gap width, which in preferred embodiments is less than 1°, or less than 0.1 mm, and in general.

[0095] It is to be noted that the gap width may vary for different gaps 116, because the cutting system is subject to wear, and so the size of the segments 111 may progressively increase because of burrs remaining along the lateral sides 112 (as well as the other sides 113, 114). The progressive increase is not to be intended as each successive segment 111 being necessarily bigger than the previous one, but as a stochastic increase, for which an average size of several segments 111 increases until maintenance is performed.

[0096] The span angle may be always the same, in case all the lamination segments 111 have all the same angular width, or may vary depending on the size of the segments 111.

[0097] For example, for lamination segments 111 having an angular width of almost 60°, one layer group includes six lamination segments 111. After the first one is received, there is a rotation of 60°. Then, a new lamination segment 111 is received, and the stacking support 4 is rotated again, until the six lamination segments 111 of the layer group are all arranged side-by-side forming a complete layer 110.

[0098] The span angles can be pre-stored in the control unit, for example in the form of a table, both in case of a constant span angle and in case of different span angles for different segments 111 having different angular widths.

[0099] In an alternative embodiment, the control unit may be configured to set the span angle by means of a closed loop control, based on measuring or estimating a position of a last placed segment 111 and a size of a segment 111 to be placed. For this purpose, the apparatus 1 may comprise appropriate sensors, not shown. In this case, even if all the lamination segments had the same angular width, the span angles are expected to be generally different to each other.

[0100] In still another embodiment, the control unit may be configured to run an artificial intelligence algorithm configured to calculate appropriate span angles for the lamination segments 111.

[0101] It goes without saying that the span angle is always rotated in the same rotation orientation, at least until one layer 110 has been completed, in order not to overlap lamination segments 111 of the same layer group. Instead, it is not to be ruled out that for another layer 110 the opposite rotation orientation is selected.

[0102] Upon manufacturing a plurality of lamellar packs 100, as commented above, wear causes the cutting system 2 to cut segments 111 with increasing burrs, which reduce the gap width.

[0103] Thus, the cutting system 2 is first set to cut segments 111 with respective starting angular widths, such as to leave gaps 116 with a starting width between adjacent lamination segments 111. The starting angular widths of the segments 111 are usually the widths obtained by cutting the lamination sheet 200 while the cutting edges of the matrix 21 and punch 22 are sharp.

[0104] After iteratively manufacturing lamellar packs 100, the cutting edges wear and are less sharp. Thus, the actual gap width reduces below the starting gap width. Then, maintenance can be performed on the cutting system 2 to sharpen again the cutting edges and set the gap width back to the starting gap width.

[0105] Preferably, maintenance is decided based on monitoring a wearing parameter linked to the progressively reduction of the width of the gap 116. One example of monitored wearing parameter is the gap width itself. Another example is the size of burrs along one or more edges 112, 113, 114 of the segments 111.

[0106] The monitoring can be performed automatically, by appropriate sensors such as image sensors, or by an operator with proper tools, such as a microscope, and can be performed on all the segments 111 or on samples thereof.

[0107] Maintenance is decided upon the wearing parameter passing a wearing threshold, such as the gap width becoming smaller than a minimum width threshold, or the burrs size becoming greater than a maximum burr threshold.

[0108] When a layer 110 has just been completed, different rotation options may be selected for the stacking support 4 before receiving the successive lamination segment 111, for the successive layer 110 to be formed over the completed layer 110.

[0109] One option provides that no rotation is performed at this stage. In this case, the incoming lamination segment 111 is received exactly over a lamination segment 111 of the previous, completed layer 111. It is to be noted that, in this manner, in case all the lamination segments 111 have the same angular width, the gaps 116 of successive layers 110 are aligned in the axial direction Z-Z. This is not preferred, since the gaps 116 are discontinuities in the layers 110, having a negative impact on the electromagnetic field. In case they are aligned in the axial direction Z-Z, this negative effect is concentrated in few circumferential positions.

[0110] Another option equivalent to the previous one is that, after completion of a layer 110, the control unit is configured to control the rotation means 6 to rotate the stacking support 4 by a stagger angle equal to the span angle, or to a multiple thereof. Also in this case, the gaps 116 of the successive layers 110 will be aligned in the axial direction Z-Z.

[0111] The preferred option is that, after completion of a layer 110, the control unit is configured to control the rotation means 6 to rotate the stacking support 4 by a stagger angle, that is different from the span angle, and different from multiples thereof. In this case, just in order to minimize rotation, it is preferred that the stagger angle is smaller than the angular width of a lamination segment 111, and more preferably smaller than half such angular width.

[0112] In this manner, the first lamination segment 111 of the new layer 110 partially overlaps two distinct lamination segments 111 of the previous completed layer 110. Thus, segments 111 of different layers 110 can be fixed by glue, and segments 111 of the same layer can be blocked to each other by gluing to common segments 111 of other layers.

[0113] In this embodiment, the gaps 116 of these two layers 110 are not aligned in the axial direction Z-Z. By selecting a small stagger angle, that is always rotated in the same angular orientation for plural completed layers, the gaps 116 of these layers will be arranged in a helical fashion, minimizing the circumferential concentration of the related electromagnetic effects. For example, if the stagger angle is a submultiple of the span angle, an axial alignment of the gaps 116 will only occur for two layers 110 which are spaced from each other by some intermediate layers 110. The stagger angle may also be rotated in opposite orientations for alternate layers 110. In this case, the gaps 116 are not arranged in a helical fashion, but in a zigzag fashion, with only a minor reduction of the axial alignment, as alignment will occur every two layers 110.

[0114] Still another option is a mix of the formerly described ones. For example, there may be no rotation after completion of a predetermined number of layers 110 followed by a rotation by a stagger angle for the subsequent layer. This may result in a helical or zigzag fashion for bricks of lamination segments 111 covering plural layers 110.

[0115] In general, a stagger angle may be provided after completion of just one lamination layer 110, but it is preferred that it is provided after completion of each of a plurality of lamination layers 110, and even more preferably after completion of each lamination layer 110 of the lamellar pack 100, until completion of the lamellar pack 100.

[0116] The height regulation system 7 is configured to move the lamellar pack 100 in the axial direction Z-Z, within the stacking support 4, in order to keep the lamellar pack 100 at a desired height. Preferably, the height regulation system 7 is configured to keep a substantially constant axial distance between the top layer 110 of the lamellar pack 100 being formed, and the lamination sheet 200, or the main matrix 21. In other words, the height regulation system 7 is configured to keep the top layer 110 of the lamellar pack 100 at a substantially constant axial position.

[0117] It is to be noted that, with the progression of the manufacturing process, the lamellar pack 100 being formed becomes greater in the axial direction Z-Z. Therefore, in order to keep constant the above distance, the support surface 41 is lowered after completion of any lamination layer 110. In particular, it is lowered by an axial distance equal to the thickness of one lamination layer 110.

[0118] In the preferred embodiment, the top layer 110 of the lamellar pack 100 being formed is kept proximate to the main matrix 21, possibly in contact therewith. In more detail, the distance between the top layer 110 of the lamellar pack 100 being formed and the lamination sheet 200 is kept substantially equal to the thickness of one lamination layer 110.

[0119] Thus, the main punch 22, upon cutting a lamination segment 111 out of the lamination sheet 200, is also configured to press the lamination segment 111 being cut against the top layer 110 of the lamellar pack 100 being formed. Preferably, the height regulation system 7 is configured to hold the pressure of the main punch 22 pressing the lamination segment 111 onto the top layer 110.

[0120] Therefore, the lamellar pack 100 being formed is repeatedly pressed on one side, by the height regulation system 7, and in particular by the support surface 41, and on the other side by the main punch 22, and possibly by the main matrix 21. This ensures proper adhesion of the lamination layers 110, and reduction of the overall axial dimensions of the lamellar pack 100.

[0121] In the preferred embodiment, after completion of the lamellar pack 100, the height regulation system 7 is configured to lower the lamellar pack 100 outside the perimetral wall 42, for removal of the lamellar pack 100 from the stacking support 4.

[0122] From the above it is clear also the method of manufacturing the lamellar pack 100, whose main steps are repeated below. The lamination segments 111 are sequentially cut out of the lamination sheet 200. Preferably, steps of advancing the lamination sheet 200 are alternated to steps of cutting the lamination segments 111.

[0123] The lamination segments 111 are sequentially received in the stacking support 4,

[0124] Between receiving successive lamination segments 111 of one and the same layer group, the stacking support 4 is rotated by a span angle, such that the lamination segments 111 of the layer group are received side-by-side to form a lamination layer 110 of the lamellar pack 100, and gaps 116 are left between adjacent segments 111 of a layer 110.

[0125] Preferably, after completion of at least one layer 110 of the lamellar pack 100, possibly after completion of each layer 110, optionally except after completion of the final layer 110, the stacking support 4 is rotated by a stagger angle. The stagger angle is selected such that a successive lamination segment 111, for a successive layer 110 of the lamellar pack 100 to be formed over the completed layer 110, partially overlaps two distinct lamination segments 111 of the completed layer 110.

[0126] Preferably, steps of rotating the stacking support 4 are alternated to steps of cutting the lamination segments 111.

[0127] In a method of manufacturing plural lamellar packs 100, the cutting system is first set to cut lamination segments 111 with respective starting angular widths, and then lamellar packs are iteratively manufactured based on the above method. The starting angular widths are selected such that gaps 116 with starting gap widths are left between adjacent segments 111.

[0128] A wearing parameter is monitored, while the lamellar packs 100 are manufactured. The wearing parameter is linked to progressively reduction of the width of the gap 116. Upon the wearing parameter passing a wearing threshold, the cutting system is maintained to set the width of the gap 116 back to the starting width.

Claims

CLAIMS1. An apparatus (1) for manufacturing lamellar packs (100) for electric motors for automotive applications, comprising:- a cutting system (2), configured to cut lamination segments (111) out of a lamination sheet (200), each lamination segment (111) having a predetermined shape to define an annular sector of a lamination layer (110) of a lamellar pack (100),- an adhesive dispenser (5), configured to apply an adhesive upon the lamination segments (111) cut from the lamination sheet (200), or upon regions of the lamination sheet (200) to be cut as lamination segments (111),- a stacking support (4) configured to sequentially receive the lamination segments (111),- rotation means (6), configured to rotate the stacking support (4) about a rotation axis, and- a control unit configured, upon the stacking support (4) receiving in sequence a predetermined layer number of lamination segments (111), forming a layer group of lamination segments (111), to control the rotation means (6) to rotate the stacking support (4) by a span angle, between the stacking support (4) receiving successive lamination segments (111) of the layer group, the span angle being selected such that the lamination segments (111) of the layer group are received adjacent to each other to form a lamination layer (110) of the lamellar pack (100), characterized in that the cutting system (2) is configured to cut the lamination segments (111) with respective angular widths, selected such that a gap (116) is left between each couple of adjacent lamination segments (111) of the lamination layer (110).

2. The apparatus (1) of claim 1, wherein:- each lamination segment (111) has an inner side (113), an outer side (114) and two lateral sides (112),- the angular widths are selected such that, for each couple of adjacent lamination segments (111), two lateral sides (112) of respective lamination segments (111) face each other and are not in contact with each other.

3. The apparatus (1) of claim 1 or 2, wherein the angular width of a lamination segment (111) is smaller than the span angle selected for rotation of the stacking support (4) after the stacking support (4) receives the lamination segment (111), in order for adjacent lamination segments (111) to be spaced from each other.

4. The apparatus (1) of any claim 1-3, wherein the control unit is configured, after completion of at least one layer of the lamellar pack (100), to control the rotation means (6) to rotate the stacking support (4) by a stagger angle, selected such that a successive lamination segment (111), for a successive layer (110) of the lamellar pack (100) to be formed over the completed layer (110), partially overlaps two distinct lamination segments (111) of the completed layer (110).

5. The apparatus (1) of claim 4, wherein:- the stagger angle, selected for rotation of the stacking support (4) after completion of alamination layer (110), is different from the angular widths of the lamination pieces (111) of the lamination layer (110) and from multiples thereof, preferably smaller than such angular widths, more preferably smaller than half such angular widths.

6. The apparatus (1) of claim 4 or 5, wherein the control unit is configured to control the rotation means (6) to rotate the stacking support (4) by one and the same stagger angle, in one and the same rotation orientation, after completion of at least each layer of the lamellar pack (100) not being a final layer of the lamellar pack (100).

7. The apparatus (1) of any claim 1-6, wherein the cutting system (2) comprises:- a main matrix (21), arranged above the stacking support (4), the main matrix (21) being configured to support a lamination sheet (200), and including a hole (23) with a cutting edge matching a main outline of the lamination segments (111), being a closed line enveloping the predetermined shape of the lamination segments (111), and- a main punch (22), matching said main outline of the lamination segments (111), the main punch (22) being configured to push a region of the lamination sheet (200) through the hole (23) of the main matrix (21), so as to cut a lamination segment (111) along the main outline out of the lamination sheet (200).

8. The apparatus (1) of claim 7, wherein the cutting system (2) comprises:- one or more auxiliary matrixes (24), arranged upstream the main matrix (21) in a sliding direction of the lamination sheet (200), and- one or more auxiliary punches (25), each auxiliary punch (25) being configured to cooperate with a respective auxiliary matrix (24) to cut a detail of the predetermined shape of the lamination segments (111), preferably said detail including a slot opening (115) for the lamellar pack (100).

9. The apparatus (1) of claim 7 or 8, comprising a height regulation system (7), configured to move the lamellar pack (100) in the stacking support (4) so as to keep a top layer of the lamellar pack (100) being formed proximate to the main matrix (21), and to hold a pressure of the main punch (22) pressing a lamination segment (11 l)segment.

10. A method of manufacturing a lamellar pack (100) for an electric motor for automotive applications, comprising:- sequentially cutting lamination segments (111) out of the lamination sheet (200), each lamination segment (111) having a predetermined shape to define an annular sector of a lamination layer (110) of a lamellar pack (100), with a respective angular width,- upstream cutting the lamination segments (111), sequentially applying an adhesive upon regions of a lamination sheet (200) corresponding to lamination segments (111) to be cut, or downstream cutting the lamination segments (111), sequentially applying an adhesive upon the lamination segments (111),- sequentially receiving the lamination segments (111) in a stacking support (4),- between receiving in the stacking support (4) successive lamination segments (111) of a layer group, including a predetermined layer number of lamination segments (111),rotating the stacking support (4) by a span angle, such that the lamination segments (111) of the layer group are received adjacent to each other to form a lamination layer (110) of the lamellar pack (100), the angular width of the lamination segments (111) being selected such that a gap (116) is left between each couple of adjacent lamination segments (111) of the lamination layer (110).

11. A method of manufacturing a plurality of lamellar packs (100) for a plurality of electric motors for automotive applications, comprising:- providing an apparatus according to any claim 1 -9, - setting the cutting system (2) such as to leave a gap (116) with a starting width upon receiving adjacent lamination segments (111) in the stacking support (4),- iteratively manufacturing lamellar packs (100) according to the method of claim 9,- monitoring a wearing parameter linked to progressively reduction of the width of the gap (H6), - upon the wearing parameter passing a wearing threshold, maintaining the cutting system to set the width of the gap (116) back to the starting width.

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