BRAKE DEVICE FOR THE REALIZATION OF LAMINAR PACKAGES FOR ELECTRICAL USE

Abstract

A brake device (10, 10′) for the realization of laminar packages for electrical use defined by the overlapping of magnetic laminations formed by shearing, coupled to a shearing apparatus (13) below a shearing mould (14), with said brake device comprising a brake block (15, 15′), provided with an opening (16, 16′) with a shape corresponding to that of a lamination (12′) and with a size smaller than that of the lamination to define with said lamination an interference (Δ) functional to the packing of the laminations (12) and comprising mechanical stress compensation means adapted to keep said interference (Δ) constant.

Claims

1. A brake device (10, 10′) for the realization of laminar packages for electrical use defined by the overlapping of magnetic laminations formed by shearing, coupled to a shearing apparatus (13) and below a shearing mould (14), with said brake device comprising a brake block (15, 15′) provided with an opening (16, 16′) formed according to an axial direction of movement of a shearing element of the shearing apparatus (14) and with a shape corresponding to that of a lamination (12′) sheared by said shearing element and with a size (A1) smaller than a size (Δ) of the shearing mould (14) that forms the lamination to define an interference (Δ) functional to the packing of the laminations (12′), and characterized in that it comprises mechanical stress compensation means adapted to keep said interference (Δ) constant and comprising pockets (18, 18′) formed outside the opening (16, 16′) of the brake block (15,15′) and extended in the thickness of the axial development of said brake block and along the peripheral edge of the opening (16, 16′).

2. The brake device according to claim 1, characterized in that the pockets (18, 18′) are formed in zones of the brake block (15, 15′) at stress intensification zones of the lamination (12′) corresponding to weakening areas of the shearing element where there is a greater concentration of stresses.

3. The brake device according to claim 1, characterized in that the pockets (18, 18′) are of the through type.

4. The brake device according to claim 1, characterized in that the pockets (18, 18′) are of the blind type.

5. The brake device according to claim 1, characterized in that the pockets (18′) are axially extended in the thickness of the brake body (15′) and are distributed according to a radial direction.

6. The brake device according to claim 1, characterized in that the pockets (18, 18′) have an extension in length corresponding to the extension of the stress intensification zones of the lamination (12′).

7. The brake device according to claim 1, characterized in that it comprises at least one pocket (18, 18′) at each stress intensification zone of the lamination (12′).

8. The brake device according to claim 1, characterized in that the brake block (15, 15′) comprises a thin wall or membrane (19) separating the pocket (18, 18′) and the opening (16, 16′) defining an elastic wall or membrane functional to an expansion of the pockets (18, 18′) as a function of the deformations of the lamination (12′).

Description

[0027] The constructive and functional features of the brake device for the realization of laminar packages for electrical use of the present invention can be better understood from the following detailed description in which reference is made to the attached drawings which represent a preferred and non-limiting embodiment and in which:

[0028] FIG. 1 schematically depicts an axonometric view of a laminar package with a “T” profile;

[0029] FIG. 2 schematically depicts a sectional view of a lamination shearing and packing apparatus comprising the brake device of the invention;

[0030] FIG. 3 schematically depicts a plan view of the brake device for the realization of laminar packages of the invention;

[0031] FIG. 4 schematically depicts an axonometric view of the brake device of the invention according to a configuration of an alternative embodiment.

[0032] The brake device for the realization of laminar packages for electrical use of the invention is described, with reference to FIGS. 1 to 3, referring to the realization of a laminar package with a “T” profile, i.e., a laminar package consisting of a plurality of individual “T”-shaped laminations 12′ overlapping one another to form the aforementioned package 12 which forms a portion or module of a laminar package, for example discoidal, of a rotor or stator core (the features of such laminar package are not described in detail herein, as known).

[0033] FIG. 2 schematically illustrates a shearing apparatus 13 comprising a shearing mould 14 and the brake device 10 which, as is known, is arranged below the shearing mould 14, with the brake device 10 which, as described above, has a size A1 slightly smaller than the size A of the shearing mould 14 in order to generate an interference “A” necessary for packing the laminations 12′ (in the case of a discoidal-shaped lamination, the sizes A and A1 are indicative of the diameters of the shearing mould and the brake device).

[0034] FIG. 3 depicts a sectional plan view of the brake device 10 of FIG. 2 comprising a brake block 15 (made of steel or sintered material, composite material or other material suitable for the purpose) provided with an opening 16 formed according to an axial direction of movement of a shearing element (not depicted) of the shearing apparatus 13; the shape of said opening 16 is realized as a function of the type of profile of the lamination 12′ sheared to form the laminar package 12 and in the specific case of FIG. 3, the shape of the opening 16 of the block 15 is of the “T” type, i.e., like the shape of the laminar package 12 of FIG. 1.

[0035] Outside the opening 16 and along the peripheral edge of said opening, through or blind-type pockets 18 are formed which extend in the thickness of the block 15 of the brake device 10.

[0036] Said pockets 18 preferably have a shape in cross section (according to a plane perpendicular to the extension direction thereof in the thickness of the block 15) of the slotted type; it is to be understood that the shape of said pockets can also be different.

[0037] The pockets 18 are realized at the stress intensification zones of the lamination 12′, i.e., in the regions thereof where there is a greater concentration of stresses (for example, at the edges or in zones where there are section variations, etc.); said stress intensification zones of the lamination 12′ correspond to weakening areas of the shearing element.

[0038] A single pocket 18 is arranged at each specific and predefined yielding zone of the brake block 15 corresponding to the yielding zones of the lamination, with an extension in length, according to a plane perpendicular to the extension direction of the same pocket in the thickness of the block 15, which substantially corresponds to the extension of said yielding zones of the lamination 12′; in particular, the size in length and width of the single pocket 18 is a function of the deformation of the single lamination 12′ sheared by the shearing element.

[0039] At a single yielding zone of the block 15 there is at least one pocket 18, the number of said pockets is a function of the extension of the yielding zone of the block 15 and, therefore, is a function of the magnitude of the predefined stresses (as they are pre-calculated during the design step of the type of laminar package to be made).

[0040] Between the single pocket 18 and the opening 16 of the block 15 there is therefore a block portion 15 defining a thin wall or membrane 19 separating said pocket from the opening 16 whose function will appear clearer below.

[0041] Said pockets 18, by virtue of the position thereof and the presence of the thin wall or membrane 19, form a “shock absorber” during the shearing and packing process of the laminations; more in particular, said pockets 18 expand during the shearing of the lamination, allowing an absorption of the deformations of the thin wall or membrane 19 caused by the interference between the lamination and the brake device as described above.

[0042] The position of the pockets 18 is a function of the deformation of the yielding zones or areas of the block 15 of the brake device 14 and, more specifically, said pockets 18 are positioned and realized so that they can all expand (given the presence of the thin wall or membrane 19 defining an elastic wall or membrane) by the same amount when subjected to the same force; in fact, the size increase of the lamination is assumed to be the same on the entire perimeter of the lamination during the useful life of the shearing mould (considering what has been described above, in fact, the size of the lamination is a function of the shearing clearance of the shearing element which is the same on the entire shearing profile).

[0043] With reference to FIG. 4, an alternative embodiment for the brake device of the invention is illustrated, indicated overall with 10′ and comprising a brake block 15′ (likewise made of steel or sintered material, composite material or other material suitable for the purpose) provided with an opening 16′ formed according to an axial movement direction of a shearing element (not depicted) of the shearing apparatus 13; the shape of said opening 16′ is realized as a function of the type of lamination profile (for example, a circular lamination) sheared to form the laminar package. Outside said opening 16′ and along the peripheral edge of said opening, pockets 18′ are formed which, according to such an embodiment, extend axially in the thickness of the brake body 15′ for a finite length to define a blind pocket and are distributed according to a radial direction.

[0044] In the embodiment shown in FIG. 4, said pockets 18′ are formed transversely to the longitudinal/axial extension direction of the brake body starting from the outer side surface 15B of the brake body in the direction of the inner side surface 15C of the brake body 15 at the opening 16′ to define pockets which are laterally open or are through along the aforementioned transverse direction; however, said pockets can also be blind along the aforementioned transverse direction to define a membrane or thin wall as previously described between said single pockets and the opening 16′.

[0045] The presence of the pockets 18 (18′) allows the brake device 10 (10′) to self-adapt to the shape of the lamination during the shearing process of the laminations themselves.

[0046] Mechanical tests carried out on the device at different force conditions applied to the opening 16 (16′) of the brake block 15 (15′) of the brake device 10 (10′) have revealed that the displacement trend (measured in millimetres) (graph 1) of the yielding element (defined by the pockets 18 (18′)) and the stress trend (measured in megapascals [MPa]) (graph 2) thereon are linear as a function of the force applied.

[0047] FIGS. 1 to 3 illustrate the brake device for the realization of laminar packages with a “T”-type profile; it is to be understood, however, that the stress compensation or “shock absorbing” means described above can also be applied to laminations with different profiles such as, for example, discoidal-profile laminations and the like.

[0048] As can be seen from the foregoing, the advantages achieved by the brake device for the realization of laminar packages of the present invention are evident.

[0049] The brake device for the realization of laminar packages of the present invention advantageously allows to prevent the breakage of the shearing elements during the lamination shearing processes.

[0050] A further advantage of the brake device of the invention is represented by the fact that it allows to eliminate pickups on the sheared profiles.

[0051] Further advantageous is the fact that the “shock-absorbing” behaviour of the brake device of the invention allows to keep the “A” constant between the brake and the sheared lamination and, consequently, avoids the occurrence of interference forces which tend to cause the shearing element to break.

[0052] Additionally, advantageous is the fact that the elastic behaviour of the brake device allows a reduction in the number of sharpenings of the moulds and, consequently, allows a reduction in the machine stops and related costs.

[0053] A further advantage is that the pockets of the brake device define a yielding element of the same brake and, in the event of excessive expansion of the sheared lamination, the breakage of such a yielding element will occur and not of the shearing element, resulting in cost savings, considering that the shearing element and the mould have a much higher cost than that of the brake device.

[0054] Further advantageous is the fact that the brake device of the invention allows to ensure an optimal quality of the sheared laminations and, therefore, allows the realization of a laminar package characterized by optimal efficiency, absence of vibration and/or noise in the electric machines which mount the aforementioned laminar package.

[0055] Although the invention has been described above with particular reference to an embodiment given merely by way of non-limiting example, numerous modifications and variations will be apparent to a person skilled in the art in the light of the above description. Therefore, the present invention intends to embrace all the modifications and variations which fall within the scope of the following claims.