The present invention relates to a device for shearing moulds for sheets for electrical use.

More in particular, the present invention relates to a device applied in shearing moulds for making metal sheets functional for forming lamellar packs for electrical use in electrical machines such as motors, generators, transformers, counters, ignition coils and similar electrical equipment.

As is known, the magnetic sheets necessary for forming lamellar packs are obtained starting from a metal sheet subjected to shearing operations by means of dedicated moulds which, for the purpose, comprise elements which in jargon are defined "special functions", i.e., mechanical elements of a mould activated manually or by a pneumatic or hydraulic piston which enable/disable one or more shearing elements of a mould.

An example of a "special function" is a type of sheet packaging made in progressive moulds in which the sheets which are superimposed are each provided with protruding braces which go to define a cavity at the opposite surface (with respect to that of the brace) and with the brace of a sheet which is constrained in the cavity of the adjacent sheet and with a further sheet which is interposed between two adjacent sheets constrained together and which is provided with a through opening adapted to be crossed by the brace of a sheet which couples with the cavity of the adjacent sheet; in this case the special function is activated and deactivated at each press stroke.

In a progressive type mould such as the one described above for the specific packaging solution, there may be a plurality of "special functions" and by means of act ivat ing/deact ivat ing such functions it is possible to activate or deactivate the shearing punches and thereby obtain sheared products (e.g., sheets) with multiple geometries or shapes.

Typically, the activation/deactivation of the above functions occurs by means of dedicated apparatuses placed within the mechanical structures of the shearing moulds and comprising movement bars, sliders and containment plates thereof which require considerable spaces and which are driven by an external control and command unit by means of pneumatic or hydraulic pulses.

Therefore, the traditional apparatuses have a significant drawback represented by the considerable dimensions and weight of said apparatuses.

Known solutions of this type are described in US4623089 or US5144872 or US8770077, which describe shearing moulds, characterized by complex mechanical structures with considerable dimensions and weights.

A further drawback of the traditional apparatuses is that they are capable of activating the shearing punches only simultaneously in each shearing step.

A further drawback of the traditional type of apparatus is represented by mechanical problems defined by breakage and jamming of the mechanisms for activating/transmitting the movements to the shearing punches.

Known solutions having these types of drawbacks are described in EP0963802 or DE202005010990 or EP3789133 or DE4135787 or US5771565, which refer to shearing devices comprising a plurality of punches whose movement is activated/deactivated as a function of shearing needs with mechanical means of the piston or lever type.

A further drawback, and consequence of the above drawback is represented by the costs of maintenance, replacement, repair of the broken or jammed mechanisms, which affect production cost s .

The ob j ect of the present invention is to overcome the drawbacks described above .

More in particular, the ob j ect of the present invention is to provide a device for shearing moulds for electrical use with limited dimensions and such that it can be easily installed within a shearing mould .

A further ob j ect of the present invention is to provide a device which reduces , if not considerably cutting down, the chances of witnes sing any breakage and/or j amming of the mechanisms for transmitting the motion to the shearing punches .

A further ob j ect of the present invention is to provide a device for shearing moulds which allows the shearing punches to be activated simultaneously or selectively/ individually within the same shearing step .

A further ob j ect of the present invention is to provide a device for shearing moulds which is simple to manage with reference to maintenance or repair or replacement interventions , with a containment of the related costs .

A further ob j ect of the present invention is to provide users with a device for shearing moulds for electrical use adapted to ensure high reliability and resistance over time and such as to be easily and economically made .

These and other ob j ect s are achieved by the invention having the features according to claim 1 .

According to the invention, a device is provided for shearing moulds for sheet s for electrical use functional for forming lamellar packs for electrical use in electrical machines such as motors , generators , trans formers , counters , ignition coils and similar electrical equipment , comprising a boxlike body housed inside a plate of a shearing mould and comprising means for a simultaneous or selective act ivat ion/deact ivat ion of shearing punches of said shearing mould in a shearing step, said activation/deactivation means being in corresponding number to the number and pos ition of said punches .

Advantageous embodiment s of the invention appear from the dependent claims .

The constructive and functional features of the device for shearing moulds for sheet s 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 illustrate an embodiment provided solely by way as a non-limiting example , in which : figure 1 schematically illustrates an axonometric view of the device for shearing moulds for sheet s for electrical use of the present invention ; figure 2 schematically illustrates a view of the device of the invention in cros s-section according to a vertical plane ; figures 3 and 4 schematically illustrate a cros s-sectional view of the device of the invention according to a vertical plane , with each figure illustrating the movement sequence of the device of the invention ; figure 5 schematically illustrates an axonometric view of the device of the invention according to an embodiment alternative to the embodiment referred to in figure s 1 to 4 ; figures 6 and 7 schematically illustrate a view of the device of figure 5 in cros s-section according to a vertical plane , with each figure illustrating the movement sequence of the device of the invention .

With reference to the aforementioned figures , the device for shearing moulds for sheet s for electrical use of the present invention, indicated overall with 10 in figure 1 and in figures 2 to 4 , comprises a box-like body 12 adapted to be housed inside a plate 14 of a shearing mould ( figure 2 ) comprising shearing punches 15 and abutting spacer means 16 for said shearing punches functional for a movement according to an advancement /retraction direction of said shearing punches according to the modes better described below for the purpose of activating/deactivating specific shearing functions (known as "special functions") .

The spacer means 16 comprise elastic elements 16' cooperating with said spacer means for an elastic return of the shearing punches 15 activated/deactivated as described below.

The spacer means 16 and therefore the shearing punches 15 are activated/deactivated in their movement by means of operating elements arranged within the box-like body 12.

The box-like body 12 comprises an upper block 12' and a lower block 12' ' hermetically and rigidly constrained to each other with retaining means of known type such as screws and the like .

The lower block 12' ' has through holes or openings 12B formed in the thickness of its base and functional for accommodating a portion of the spacer means 16 to which the shearing punches 15 are connected; the number and arrangement of said through holes or openings 12B corresponds to the number and position of the shearing punches 15.

The means for activating/deactivating the shearing punches 15 are arranged within the lower block 12' ' , which comprise sliders 18 movable in translation within dedicated seats 19 formed in said lower block 12' ' , with said sliders 18 cooperating with elastic elements 20 likewise housed in said seats 19 and preferably defined by compression springs.

The sliders 18, in the preferred embodiment referred to in the figures, comprise a head portion 18' and a tail portion 18' ' (oriented in the direction of the elastic elements 20) with different dimensions in height and, in particular, with the height of the tail portion 18' ' lower with respect to that of the head portion 18 ' .

The number of sliders 18 and, therefore , of the elastic element s 20 and of the relative housing seat s 1 9 corresponds to the number of shearing punches 15 which must be act ivated/deact ivated in the desired shearing step .

In the preferred embodiment referred to in the figures , the sliders 18 are arranged according to a radial direction with a forward/backward sliding movement with respect to the centre of the lower block 12 ' ' .

In accordance with alternative embodiment s to that described above , the sliders 18 can be arranged in accordance with dif ferent geometries with respect to the radial one and this as a function of the specific production requirements .

The sliding movement of the sliders 18 within the seat s 1 9 occurs by means of a flow of compres sed air fed through a fitting 22 fixed to the box-like body 12 and distributed in the aforementioned seat s 1 9 by means of a distributor assembly 24 also arranged inside the box-like body 12 at the centre thereof .

The operation of the device for shearing moulds for electrical sheet s of the present invention, described above in detail with reference to it s constructive features , is explained below with reference to the embodiment referred to in figures 1 to 4 .

With reference to figures 2 and 3 , the condition is illustrated in which, in a shearing stroke , the shearing punches 15 are deactivated and are not shearing .

In such a condition, the sliders 18 are in a resting endstroke position in the respective seat s 1 9 at the centre of the lower block 12 ' ' of the box-like body 12 and are maintained in such a position by the action of the elastic element s 20 with the spacer means 1 6 and, therefore , with the shearing punches 15 which, due to the shearing force of the mould, rise ( as indicated by the arrow "X" in figure 3 ) in the thickness of the mould plate 14 and in the lower block 12 ' ' of the box-like body 12 , abutting the tail portion 18 ' ' of the slider 18 and resulting in a non-shearing action of the sheet ( in particular, the spacer means 16 engage with the tail portion 18 ' ' of the slider 18 ) .

With reference to figure 4 , the condition is illustrated in which, in a shearing stroke, the shearing punches 15 are activated and are shearing .

For the activation of the shearing punches 15 , compressed air is fed to the box-like body 12 through the fitting 22 and distributed to the individual sliders 18 through the distributor assembly 24 and, as a result of the action of the air, the sliders 18 slide radially away from the centre of the lower block 12 ' ' , compressing the elastic means 20 (as indicated by the arrows "Y" in figure 4 ) ; with this sliding movement the sliders 18 go to close the through holes or openings 12B of the lower block 12 ' ' in which portions of the spacer means 16 slide (the spacer means come into contact with the head portion 18 ' of the slider 18 ) and the shearing punches 15 enter the die of the shearing mould and shear the large sheet to make the sheets .

Then when the shearing punches 15 must not shear during the subsequent shearing strokes , the supply of compressed air to the box-like body is disabled and the individual sliders 18 are returned to the resting position at the centre of the lower block 12 ' ' due to the action of the elastic means 20 and the device is returned to the condition referred to in figure 2 or 3 .

With reference to the embodiment of figures 1 to 4 , when compressed air is fed to the box-like body 12 , the sliders 18 are slidably driven simultaneously by simultaneously activating the shearing punches 15 . With reference to figures 5 to 7, an alternative embodiment of the device of the invention is illustrated, indicated overall with 10' , in accordance with which the shearing punches can be selectively activated/deactivated .

In the description of the alternative embodiment, the same reference numerals of the embodiment referred to in figures 1 to 4 will be maintained to indicate the analogous components .

The device 10' comprises a box-like body 30 comprising an upper block 30' and a lower block 30' ' hermetically and rigidly constrained to each other with retaining means of known type such as screws and the like.

The lower block 30' ' has through holes or openings 30B formed in the thickness of its base and functional for accommodating a portion of the spacer means 16 to which the shearing punches 15 are connected; the number and arrangement of said through holes or openings 30B corresponds to the number and position of the shearing punches 15.

The means for activating/deactivating the shearing punches 15 are arranged within the lower block 30' ' , which comprise sliders 34 movable in translation within dedicated seats 36 formed in said lower block 30' ' , with said sliders 34 cooperating with elastic elements 35 likewise housed in said seats 36 and preferably defined by compression springs.

The sliders 34, in the embodiment referred to in the figures, comprise a head portion 34' and a tail portion 34' ' (oriented in the direction of the elastic elements 35 and of the centre of the lower block 30' ' of the box-like body 30) with different dimensions in height and, in particular, with the height of the tail portion 34' ' lower with respect to that of the leading portion 34' .

The number of sliders 34 and, therefore, of the elastic elements 35 and of the relative housing seats 36 corresponds to the number of shearing punches 15 which must be act ivated/deact ivated in the desired shearing step .

In the embodiment referred to in the figures , the s liders 34 are arranged according to a radial direction with a f orward/backward sliding movement with respect to the centre of the lower block 30 ' ' .

According to alternative embodiment s to that described, the sliders 34 may have a dif ferent geometric arrangement as a function of the specific production requirement s ( as a function of the configuration of the shearing punches to be activated/deactivated) .

The sliding movement of the sliders 34 within the seat s 36 occurs by means of a flow of compres sed air fed through fittings 38 fixed to the box-like body 30 at each s lider 34 and distributed in the seat s 36 of each slider 34 .

The operation of the device for shearing moulds for electrical sheet s of the present invention, described above in detail with reference to it s constructive features , is explained below with reference to the embodiment referred to in figures 5 to 7 .

With reference to figure 6 , the condition is illust rated in which, in a shearing stroke , the shearing punche s 15 are deactivated and are not shearing .

With reference to figure 7 , the condition is illust rated in which, in a single shearing stroke of the mould, not all of them are activated simultaneously, but selectively by feeding compres sed air only to the fittings 38 at the shearing punches 15 to be activated and this so as to activate the sliding of only the sliders 34 corresponding to the punches 15 to be activated .

By feeding compres sed air into a seat 36 through a fitting 38 , the corresponding slider 34 slides in the seat 36 and moving in the direction of the centre of the lower block 30 ' ' , compres ses the elastic means 35 ( as indicated by the arrow "Y" in figure 7 ) and closes the through hole or opening 30B of the lower block 30 ' ' in which the port ion of the corresponding spacer means 1 6 slides and the corresponding shearing punch 15 enters the die of the shearing mould and shears the large sheet to make the sheet s ( as indicated by the arrow "X" in figure 7 ) , while the non-activated shearing punch 15 ( for the non-activation of the compres sed air flow) is in a resting position in abutment with the tail portion 34 ' ' of the slider 34 ( as indicated by the arrow "X" in figure 7 ) .

As can be seen from the foregoing, the advantages achieved by the device for shearing moulds for making sheet s for electrical use of the present invention are evident .

The device for shearing moulds for making sheet s for electrical use of the present invention advantageously allows to limit dimensions and weight s and, therefore, can be easily installed inside a shearing mould .

A further advantage of the device of the invention is that it is simplified with respect to the traditional devices and allows a drastic reduction of the breaking and/or j amming probabilities of the mechanisms for the transmis sion of movement to the shearing punches .

Further advantageous is the fact that the device of the invention allows a simultaneous or selective drive of the shearing punches even during a same step of the shearing mould .

A further advantage of the device of the invention is that it does not require additional plates to be able to incorporate the movement bars and the sliders to achieve the transmis sion of movement to the shearing punches , as otherwise occurs in the traditional type of devices .

A further advantage of the device of the invention is the ease of maintenance , repair and/or replacement operations , which, therefore , reduces times and the related costs .

Although the invention has been described above with particular reference to embodiment s given only 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 .