Braking device for implementing a layered assembly for electrical use

Abstract

A braking device (10, 10') for implementing an electrical laminated assembly defined by the overlapping of magnetic laminations formed by shearing, coupled to a shearing apparatus (13) below a shearing die (14), wherein said braking device comprises a braking block (15, 15') provided with an opening (16, 16') having a shape corresponding to that of the laminations (12') and having dimensions smaller than those of the laminations to define with said laminations an interference (Δ) acting on the assembly of the laminations (12'), and a mechanical stress compensation structure adapted to keep said interference (Δ) constant.

Description

Technical Field

[0001] This invention relates to a braking device for realizing a layered electrical assembly.

[0002] More specifically, the present invention relates to a braking device used in a shearing die adapted to obtain assembled or overlapping magnetic laminations from sheet metal to define layered components used in electric machinery such as motors, generators, transformers, meters, induction coils and similar electronic devices. Background Technology

[0003] As is known, the aforementioned layered components are made by overlapping individual stacks (defined by a single body or consisting of stack portions assembled together to define the stacks) by placing these individual stacks in direct contact with each other.

[0004] Conventionally, the realization of layered components occurs by overlapping and connecting individual sheets, which are obtained, for example, from a shearing die and formed by stamping, and in the case of conventional shearing methods mentioned in, for example, US2017 / 0106427 and JP6676815, these individual sheets are, for example, derived from strip sheets, and wherein the sheets, after being formed, can be overlapped and connected to each other on the same machine that formed the individual sheets, for example, as described in JP2008078345.

[0005] The stacked pieces can be connected to each other by means of connecting or hooking portions called “pins” or “protrusions”, which are obtained by deformation of the stacked pieces themselves in specially selected locations, and wherein the stacked piece portions are introduced or pressed into the recesses of the corresponding lower stacked pieces after the connecting step, so as to form an assembly of the stacked pieces by successive overlapping.

[0006] For this purpose, a rigid element, referred to as a brake, is typically arranged inside the stack shearing die and below the shearing element. This rigid element is characterized by having a reduced dimension relative to the shearing element and, through an interference fit (related to the aforementioned dimensional difference relative to the shearing element), enables the shearing element to be interrupted. As an example, in the case of shearing a circular stack and considering a shearing element with a diameter of 10 mm, the brake element must have a diameter approximately equal to, for example, 9.99 mm to define an interference fit Δ of 0.01 mm between the diameter of the stack (which will have a diameter equal to that of the shearing element) and the diameter of the brake element. This 0.01 mm interference fit generates a force in the opposite direction to the shearing load along the entire circumference of the circular shape (considering the example of a circular stack). This allows the stack to remain "tightly attached" to the inside of the brake for forming a layered assembly (a conventional brake device (or table punch) with the above features is described, for example, in EP3235577 or EP2902129, or also in US2012 / 0241095).

[0007] For the reasons stated above, it is clear that the braking element defines the basic equipment used to define the layered assembly during the realization and assembly of a single stack, and this is because the necessary reaction force can be generated solely by means of the braking element to allow interference of the assembly protrusions in the stack during the shearing process.

[0008] Therefore, such a braking element, as a rigid element, is subject to mechanical stress due to the interference between the braking element and the sheared laminations. If the stress is too high, it may cause a lift to form on the shear profile (and thus on the layered assembly), and may also cause damage to the shearing element itself.

[0009] Furthermore, it is known that the stress inside the braking element is not constant during the service life of the die; in fact, due to the wear of the shear profile and the resulting increase in the shear gap, there is an increase in size in the shear profile, which leads to a larger interference with the braking element.

[0010] An increase in interference between the pads and the braking element represents a significant and important defect, due to the fact that this interference, as noted above, is primarily caused by the formation of a raised portion on the tracked element and secondarily by the breakage of the shear element.

[0011] In fact, taking the example described above and relating to the stack obtained by a shearing element with a diameter of 10 mm, it is observed that at the beginning of the service life of the shearing die, the diameter of the obtained stack is partially equal to 10 mm (that is, the diameter is equal to the size of the diameter of the shearing element), and after a number of strokes of the shearing element (typically n million strokes) (where the value of n depends on the wear of the die), the diameter of the stack can be increased to, for example, a value equal to 10.01 mm, and considering that the braking element has a fixed size of 9.99 mm, at the beginning of the service life of the die, the size difference between the braking element and the shearing die is equal to 0.01 mm, and after a number of working cycles of "n", the same interference changes to a value equal to 0.02 mm.

[0012] Given the fact that the aforementioned increase in interference will cause problems, the increase in interference leads to an increase in the stress value in the braking element and results in the undesirable failure of both the braking element and the shear element.

[0013] This problem is particularly evident in the case of stacks with a “T” profile, where the presence of angles in the profile defines the presence of “problematic” regions, as these angles define stress-intensified regions, and thus represent the weakening points of shear elements, and stresses that can generate deformation and subsequently lead to crack formation can occur in these stress-intensified regions.

[0014] As a result, the aforementioned defects lead to a reduction in the service life of the shearing die, and as a more negative consequence, the aforementioned defects lead to an increase in the cost of the shearing die.

[0015] To reduce the above defects, the shearing die is periodically subjected to a "sharpening" operation, i.e., maintenance operation, which includes "restoring" the shearing profile to restore the aforementioned gap; this operation requires grinding the shearing elements of the die, which results in a reduction in the height of the die and thus a reduction in the service life of the die.

[0016] The aforementioned defects lead to another defect represented by the fact that the sharpening operation requires the shearing equipment to be stopped, which results in increased production time and therefore increased costs for all related processes.

[0017] Based on the related problems of performance, efficiency, unnecessary vibration and noise generation on electric machines equipped with the above-mentioned components, the deterioration of the quality of individual laminations and thus the loss of quality of the layered assembly obtained by overlapping the laminations represent another defect related to the increase of interference value. Summary of the Invention

[0018] The purpose of this invention is to overcome the above-mentioned defects.

[0019] More specifically, the object of the present invention is to provide a braking device for realizing an electrical layered assembly, which is adapted to avoid an increase in interference that may occur between the braking element and the shearing die during the lamination shearing step.

[0020] Another object of the present invention is to provide a braking device adapted to allow the absorption of deformation of the sheared stack during the shearing process of the sheared stack, thereby avoiding the possible formation of lift-off portions on the sheared profile.

[0021] Another object of the present invention is to provide a braking device suitable for preventing pre-wear and / or damage to shearing dies.

[0022] Another object of the present invention is to provide a braking device for a shearing device that allows for ensuring the quality of the sheared stack and thus allows the layered assembly to be characterized by optimal efficiency, no vibration and / or noise on the electric machine on which the assembly is mounted.

[0023] Another object of the present invention is to provide users with a braking device for realizing a layered electrical assembly, which is adapted to ensure high resistance and durability over time and is easy and economical to manufacture.

[0024] According to the present invention, a braking device is provided for realizing an electrical layered assembly defined by overlapping magnetic laminations formed by shearing. The braking device is coupled to a shearing device below a shearing die. The braking device includes a braking block having an opening having a shape corresponding to the shape of the laminations and having a size smaller than the size of the laminations to define an interference (Δ) with the laminations that acts on the assembly of the laminations. The braking device includes a mechanical stress compensation structure adapted to maintain the interference (Δ) constant. Attached Figure Description

[0025] The constructive and functional features of the braking device for realizing an electrical layered assembly will be better understood from the following detailed description, wherein reference is made to the accompanying drawings illustrating preferred and non-limiting embodiments, and in the drawings:

[0026] Figure 1 An isometric view of a layered assembly with a “T”-shaped profile is schematically depicted.

[0027] Figure 2 A cross-sectional view of a lamination shearing and assembly apparatus including the braking device of the present invention is schematically depicted;

[0028] Figure 3A schematic plan view of the braking device of the present invention for realizing a layered assembly is shown.

[0029] Figure 4 An isometric view of the braking device according to an alternative embodiment of the present invention is schematically depicted. Detailed Implementation

[0030] Reference Figures 1 to 3 The present invention describes a braking device for implementing a layered electrical assembly. Figures 1 to 3 This relates to realizing a layered assembly with a “T” profile, namely a layered assembly consisting of a plurality of individual “T” shaped laminations 12’, which overlap each other to form the aforementioned assembly 12, which forms part or module of a rotor or stator core, for example, a disk-shaped layered assembly (well-known features of such layered assemblies are not described in detail herein).

[0031] Figure 2 A shearing device 13 including a shearing die 14 and a braking device 10 is schematically illustrated. As is known, the braking device 10 is arranged below the shearing die 14, wherein, as described above, the braking device 10 has a dimension A1 that is slightly smaller than the dimension A of the shearing die 14 in order to form the interference "Δ" required for assembling the stack 12' (in the case of a disc-shaped stack, dimensions A and A1 represent the diameters of the shearing die and the braking device).

[0032] Figure 3 Depicting Figure 2 A cross-sectional plan view of the braking device 10, which includes a braking block 15 (made of steel or sintered material, composite material, or other suitable material) with an opening 16. The opening 16 is formed according to the axial movement direction of the shearing element (not depicted) of the shearing device 13; the shape of the opening 16 is determined according to the type of profile of the laminations 12' being sheared to form the layered assembly 12, and... Figure 3 In specific cases, the shape of opening 16 in block 15 is of the "T" type, that is, similar to Figure 1 The shape of the layered component 12.

[0033] A through or non-through recess 18 is formed outside the opening 16 and along the peripheral edge of the opening, the recess 18 extending in the thickness of the block 15 of the braking device 10.

[0034] The recess 18 preferably has a groove-shaped form in cross-section (according to a plane perpendicular to the direction of extension of the recess 18 in the thickness of the block 15); it will be understood that the shape of the recess can also be different.

[0035] The recess 18 is implemented in the stress-strengthening region of the lamination 12', that is, in the region of the lamination 12' where there is a large stress concentration (e.g., at the edge or in the region where there is a change in cross section); the stress-strengthening region of the lamination 12' corresponds to the weakening range of the shear element.

[0036] A single recess 18 is arranged at each specific and predefined yield region of the brake block 15 corresponding to the yield region of the laminate. The single recess 18 has a length extension range according to a plane perpendicular to the extension direction of the same recess in the thickness of the block 15, which roughly corresponds to the extension range of the yield region of the laminate 12'. In particular, the length and width dimensions of the single recess 18 are functions of the deformation of the single laminate 12' sheared by the shearing element.

[0037] At least one recess 18 exists at a single yield region of block 15, the number of which is a function of the extent of the yield region of block 15, and thus a function of the magnitude of a predefined stress (since the stress is pre-calculated during the design phase of the type of layered assembly to be manufactured).

[0038] Therefore, between the individual recess 18 and the opening 16 of the block 15, there is a block portion 15 defined by a thin wall or membrane 19, which separates the recess from the opening 16. The function of the thin wall or membrane 19 will be more clearly shown below.

[0039] By means of the location of the recess 18 and the presence of the thin wall or membrane 19, the recess 18 forms a “damping part” during the shearing and assembly process of the laminations; more specifically, the recess 18 expands during the shearing of the laminations, thereby allowing the absorption of deformation of the thin wall or membrane 19 caused by the interference between the laminations and the braking device as described above.

[0040] The position of the recess 18 is a function of the deformation of the yield region or range of the block 15 of the braking device 14, and more specifically, the recess 18 is positioned and implemented such that the recess 18 can expand by the same amount when subjected to the same force (considering the presence of the thin wall or membrane 19 defined as an elastic wall or membrane); in fact, the increase in the size of the stack is considered to be the same over the entire circumference of the stack during the service life of the shearing die (considering the above description, in fact, the size of the stack is a function of the shearing gap of the shearing element, which is the same over the entire shearing profile).

[0041] Reference Figure 4The illustration shows an alternative embodiment of the braking device of the present invention, the braking device being generally indicated by 10' and including a brake block 15' (also made of steel or sintered material, composite material or other material suitable for the purpose) having an opening 16', the opening 16' being formed according to the axial movement direction of the shearing element (not depicted) of the shearing device 13; the shape of the opening 16' being realized according to the type of lamination profile (e.g., disc-shaped lamination) being sheared to form a layered assembly. Recesses 18' are formed outside the opening 16' and along the peripheral edge of the opening, according to this embodiment, the recesses 18' extending axially for a finite length within the thickness of the brake body 15' to define different recesses, and the recesses 18' being distributed radially.

[0042] exist Figure 4 In the embodiment shown, the recess 18' is formed transversely to the longitudinal / axial direction of the brake body, extending from the outer surface 15B of the brake body toward the inner surface 15C of the brake body 15 at the opening 16', to define a recess that is laterally open or through along the aforementioned transverse direction; however, the recess may also be non-through along the transverse direction to define a membrane or thin wall located between the individual recess and the opening 16' as previously described.

[0043] The presence of the recess 18 (18') allows the braking device 10 (10') to adapt to the shape of the laminations during the shearing process of the laminations themselves.

[0044] Mechanical tests performed on the device under different force conditions applied to the opening 16 (16') of the brake block 15 (15') of the brake device 10 (10') show that the displacement tendency (measured in millimeters) of the yield element (defined by the recess 18 (18')) (Figure 1) and the stress tendency (measured in megapascals [MPa]) on the yield element (Figure 2) are linear as a function of the applied force.

[0045]

[0046] Figures 1 to 3 The illustration depicts a braking device for achieving a layered assembly with a "T"-shaped profile; however, it will be understood that the stress compensation or "damping" structure described above can also be applied to laminates with different profiles, such as, for example, laminates with a disc-shaped profile.

[0047] As can be seen from the above description, the advantages achieved by the braking device for realizing layered components of the present invention are obvious.

[0048] The braking device of the present invention for realizing a layered assembly advantageously allows for the prevention of breakage of the shearing element during the lamination shearing process.

[0049] Another advantage of the braking device of the present invention is indicated by the fact that the braking device allows the elimination of the raised portion on the sheared profile.

[0050] Even more advantageous is the fact that the “damping” behavior of the braking device of the present invention allows the “Δ” between the brake and the sheared laminations to remain constant and thus avoids interference forces that tend to break the shearing elements.

[0051] Additionally, it is advantageous that the elastic behavior of the braking device allows for a reduction in the number of times the die is sharpened, and thus a reduction in machine downtime and related costs.

[0052] Another advantage is that the recess of the braking device defines the yield element of the same brake, and in the event of excessive expansion of the sheared lamination, the failure of the yield element will occur instead of the failure of the shear element, which saves costs considering that the cost of the shear element and the mold is higher than that of the braking device.

[0053] Even more advantageous is the fact that the braking device of the present invention allows for ensuring optimal quality of the sheared laminations, and thus allows the layered assembly to be characterized by optimal efficiency, no vibration and / or noise in the electric machine on which the layered assembly is mounted.

[0054] Although the invention has been described above with particular reference to embodiments given by way of non-limiting example only, many modifications and variations will be apparent to those skilled in the art from the above description. Therefore, the invention is intended to include all modifications and variations falling within the scope of the appended claims.

Claims

1. A braking device (10, 10') for realizing an electrical layered assembly, the layered assembly being defined by overlapping magnetic laminations formed by shearing, the braking device (10, 10') being coupled to a shearing device (13) and located below a shearing die (14), wherein, The braking device includes brake blocks (15, 15') with openings (16, 16') formed according to the axial movement direction of the shearing element of the shearing device (13), and the openings (16, 16') have a shape corresponding to the shape of the stack (12') being sheared by the shearing element and have a size (A1) smaller than the size (A) of the shearing die (14) forming the stack, to define an interference (Δ) that acts on the assembly of the stack (12'), and is characterized in that the braking device (10, 10') includes mechanical A stress-compensating structure, the mechanical stress-compensating structure being adapted to maintain the interference (Δ) constant during lamination and comprising recesses (18, 18') structurally formed in the brake block outside the opening (16, 16') of the brake block (15, 15'), each recess being separated from the opening by a thin wall or membrane (19), the recesses extending along the peripheral edge of the opening (16, 16') in the axially developing thickness of the brake block, thereby elastically deforming under the stress generated by the lamination and thus maintaining the interference (Δ) substantially constant.

2. The braking device according to claim 1, characterized in that, The recess (18, 18') is formed in the region of the brake block (15, 15') located at the stress-enhancing region of the laminate (12'), the stress-enhancing region corresponding to the weakening range of large stress concentration in the shear element.

3. The braking device according to claim 1 or 2, characterized in that, The cavity (18, 18') is a through-hole type.

4. The braking device according to claim 1 or 2, characterized in that, The cavity (18, 18') is not of the same type.

5. The braking device according to claim 1 or 2, characterized in that, The recess (18') extends axially within the thickness of the brake block (15') and is distributed in the radial direction.

6. The braking device according to claim 2, characterized in that, The recess (18, 18') has a length extension range corresponding to the extension range of the stress-strengthening region of the laminate (12').

7. The braking device according to claim 2, characterized in that, The braking device includes at least one recess (18, 18') at each stress-reinforced region of the laminate (12').

8. The braking device according to claim 1 or 2, characterized in that, The brake block (15, 15') includes a thin wall or membrane (19) separating the recess (18, 18') from the opening (16, 16'), the thin wall or membrane (19) being defined as an elastic wall or membrane that acts on the expansion of the recess (18, 18') according to the deformation of the lamination (12').

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