CUTTING HEAD FOR METAL STRIP CUTTING MACHINES FOR THE MANUFACTURE OF ELECTRIC MOTOR ARMATURES

Description

ACME Holding Srl of Italian nationality, with headquarters in Via Rusca 24 / 10 17100 Savona Cutting head for tape cutting machines 5 metal for the construction of engine armatures electric ***************** DESCRIPTION TEXT 10

[0001] The present invention relates to the sector machines for making engine components electrical, in particular to make armor that they make up the stators or rotors of such motors electric. 15

[0002] These machines are designed to assemble the armor starting from originally con- kept in a warehouse where it is present in the form of semi-finished strip; the machine operates on this semi-finished strip worked in a semi-automatic way going to realize, 20 among other things, cuts or incisions on the tape and then av- turn it around a mandrel to form the said armor.

[0003] Specifically, electric motors to be pro- durre include armor involved in the generation 25 of axial-flow magnetic fields. Such ar- ripe ones are obtained by wrapping a ribbon of known material, to which a specific shape is given mature, around a rotating spindle to form a structure such as a motor nucleus having a conformation 30 spiral with radial slits.

[0004] Hereinafter, unless otherwise specified, the terms "slit" will be used in an equivalent manner, “slit”, “cave”, “groove” to indicate the radial openings obtained or obtainable in the armor rotor or stator of the motor.

[0005] Additionally, a “ribbon” of material can also be referred to as a “strip” of material, with 5 reference to elements of substantially al- shape elongated that develop along a longitudinal axis with reference to which it is also possible to define the length of the element or of a portion of it; tra- transversally to the longitudinal axis it can be identified 10 care a transverse axis of the element where to measure, among other things, the width and the so-called longitudinal axis defines a direction of advancement of the element (tape / strip) itself within the apparatus; along the direction perpendicular to the two aforementioned axes is indicated 15 the thickness of the element.

[0006] For the purposes of this description, an “engine” electric can be traced back to a “generator” electrical for the processes and components involved here resse, or the creation of armor that is not 20 prohibited from being used to convert electrical energy into mechanical energy or vice versa.

[0007] In the simplest form, motors and generators Axial flux type electric motors include essentially a stator and a rotor having the shape 25 cylindrical with the rotor positioned inside the stator. A way to produce rotors and / or stators as- siali includes the step of wrapping a ribbon of magnetic sheet metal, suitably preformed, around to a mandrel forming a sheet metal pack. 30

[0008] The sheet metal package is made in such a way such as to present a certain number of ra- grooves dial or having an orientation according to a component radial, of known shape and size to accommodate windings of electrical conductors.

[0009] Compared to other types of electric motors such as radial flow engines, radial flow engines axial have specific advantages here not further 5 discussed above but which justify the need for optimize the production processes of these devices.

[0010] There are known processes and devices for the production of spiral armatures for flux motors axial machines that perform operations on a mother belt; 10 such processes mainly include punching nature of the tape and the consequent winding of the same on a mandrel so that the spiral will once the radial grooves are present as desired.

[0011] The precision of the grooves is one of the aspects 15 critics to reach the best engine performance possible performances, measured according to various criteria such as efficiency and / or effectiveness parameters thermal, magnetic or electric. The known machines, for as the subject of improvements over the last 20 years, however, have some limitations that the re- the applicant intends to overcome, at least in part, with the present invention.

[0012] A first limitation lies in the fact that the pun- zoning is performed by equipping the pun- 25 zones chosen of specific size for cutting that must be applied to the tape. Consequently, the varia- The size of the cut can be obtained by changing the punching, an operation that must be done ma- nually and, therefore, with the intervention of an operator 30 with related machine downtime; this leads to the requires specific punches and pre-trained personnel prepared to perform this operation.

[0013] A further limitation is given by the flexibility of the machine, or the maximum number of different shapes that can be executed without having to modify and / or redesign to introduce new equipment. In a punching machine, the hesi- the need for a further new format involves the pro- 5 throwing of new equipment suitable for performing the new silhouette.

[0014] The need to make cuts of size different also occurs during the making of windings for individual components of motors having 10 the same characteristics. Varying progressively the width of the grooves in one or more portions of the band of shaped ribbon that makes up the armor is, in fact, it is possible to generate a fillet in the ra- dially more internal and / or radially more external than 15 armor grooves, with predetermined fillet radius born.

[0015] It is evident that this configuration of armor can be obtained by significantly complicating the cutting machines that operate with punches of different sizes 20 fixed, as it requires multiple point changes areas, even during the construction process of a single armor.

[0016] The purpose of the present invention is the realization installation of a head that allows automatic gear change 25 rapid punches inside a punching machine armature used for the production of as-engines be there.

[0017] The invention achieves the goal with a head cutter for metal strip cutting machines 30 for the construction of electric motor armatures trices, in particular axial flow, which head comprises a support plate of a plurality of punches arranged parallel according to a first direction ze so as to form an mxn matrix on a plane of section perpendicular to the said first z direction with m lines arranged in a second xen direction columns arranged in a third y-direction. The points 5 zones are supported translatable in the x-direction, in the y direction and in the z direction so that you can select a P punch to use for the trans- ij ciatura by translating the punch matrix so that said punch P is exposed towards the surface of the ij 10 tape to be cut and at a certain distance from said ribbon. The punches have the characteristic of being constrained to move in groups in the z-direction relative to the support plate so that the translation tion in the z-direction of approach of a punch 15 P to the cutting tape compared to the plate ij support involves approaching the tape from trans- to ciare of an entire row of P punches. the

[0018] In one embodiment, the head advantage- It comprises a first actuator, a second actuator 20 actuator and at least one cam. The first actuator acts on a first slide so as to induce a translation of the punch matrix in the x-direction, while the second actuator acts on a second slide so to induce a translation of the punch matrix 25 along the y direction. The cam is advantageously so- side with the support plate, or with an element associated with it, so that, during the translation along the y-axis of the die, the head of a punch, or an element integral with it, interferes with the 30 cam acting as a tappet inducing a translation along the z-axis of the said punch and, consequently, of the row of punches to which the said punch belongs.

[0019] The cam is preferably arranged in median position so that selecting a row of punches involves the translation of said line in the z-direction near the central part of the head. 5

[0020] The head may include a third actuator acting on the support plate or on an element in solidarity with it so as to induce a translation rigidity of the plate and, therefore, of all the punches, in the z direction so as to adjust the distance of the 10 punches relative to the strip to be cut.

[0021] In a refinement, the punches belong- items in the same row are scaled in height that is, they have an extension in the increasing z direction or decreasing. In this way it is possible to ensure 15 that punches adjacent to the working one do not interfere they come into contact with the tape during the cutting operation. tour.

[0022] Such a head allows the change punches automatically and quickly, without 20 significant production disruptions. This mi- improves the overall efficiency of the production process tive, reducing downtime and allowing for greater greater flexibility in adapting to the needs of production. 25

[0023] The easy automatic change of punches can be advantageously used to regulate in a progressive opening of the slots on the stator or ro- tore, allowing the creation of chamfers that improve engine efficiency. 30

[0024] The automation of this process not only mi- improves the accuracy and consistency of the chamfers, but It also allows for greater flexibility in optimizing engine design customization based on needs specifications. This can lead to more efficient engines and high-performance, while reducing production times tion and costs associated with manual processing.

[0025] The head which is the subject of the invention can be 5 fixed to the plate of the cutting press directly or through appropriate interfaces.

[0026] To this end, the invention also relates to a machine for cutting a ribbon comprising a support for a cutting head according to the invention 10 and a press suitable for applying a pressure force on the said support in a synchronized manner with the progress cutting of the tape. The head is advantageous- mind mounted so that the direction of the force of pressure coincides with the z direction of the punches and the 15 tape runs in the y direction.

[0027] The machine advantageously comprises a control unit interfaced with the actuators of the head and configured to select a punch of work by translating the punch matrix in the direc- 20 x and / or y tions with respect to a counter-mold element suitable for receiving the selected punch in a cavity during the tape cutting operation.

[0028] The counter-mould element, in jargon defi- finished matrix, extends longitudinally in the direc- 25 tion y of sliding of the tape to be cut and traction transversally in the x-direction it has movable walls to adjust the longitudinal length of the cavity of the countermould to the dimension in the y-direction of the selected punch. 30

[0029] In a refinement, the control unit It is configured to adjust the distance of the punches from the counter-mold before the blanking operation driving the head actuator to translate the punch matrix in the z direction so that, said s the stroke induced by the press to the head, x the di- working punch room from the counter die and the height difference between the working punch and the 5 adjacent punch of shorter length, on the same line, the working punch results in s <d in modo che said punch adjacent to the working one does not inter- wound with the counter-mold, and then with the tape, during shearing operations. 10

[0030] Since punches are typically scaled in height in the x-direction, it is appropriate that the eventual punch adjacent to the working punch of greater height greater than this (for example in the case of sele- (action of an intermediate work punch) is found 15 away from the counter die during blanking. For this reason, in a refinement, dictates the lar- width of the ribbon and lm the width of the opening from perform on the tape, the control unit is configured installment to face the work punch to the tape in 20 so that the adjacent punch, placed on the same line and facing the width part of the tape l-lm not facing the working punch, it results the one of lower height so that the said punch adjacent to the work punch does not interfere with the 25 tape during the blanking operation.

[0031] The invention also relates to a method of cutting of a metal strip for the production of electric motor armatures, in particular axial flow, comprising the following steps: 30 provide a cutting head equipped with a group of punches; place the tape on a mold matrix that is, a support surface equipped with a opening of variable dimensions suitable for receiving one of the punches during the blanking operation; select a punch from the group so that expose said punch towards the strip to be cut in 5 correspondence of the opening of the ap- surface hill; vary the size of the super opening support surface depending on the size of the selected punch; 10 move the cutting head alternately and synchronized with the movement of the tape so to make sequential cuts on the said tape of size corresponding to the size of the pun- selected zones; 15 in which the punch selection takes place by moving by the punch group so that the selected punch is found in correspondence of the opening of the support surface and to a certain distance from said surface, the movement 20 of the punch group occurring in a first direction in order to select a subgroup of punches from the group of punches and in a second direction so to select the desired punch from the subgroup of punches, the translation in the first direction indu- 25 I perform a translation through a cam device of said subgroup of punches in a third direction approaching the support surface.

[0032] Since the punches of the punch subgroups selectable from the punch group via the translation 30 action in the first direction have advantageously al- scaled teas, in a refinement the method provides to adjust the distance of the punch group from the support surface before starting the operation of blanking so that, said s the stroke of the cutting head, x the distance of the working punch from the support surface and the difference in al- between the working punch and the height punch 5 adjacent minor belonging to the punch subgroup selected by translation in the first direction, results s <d in modo che detto punzone adiacente a the work surface does not interfere with the surface of support, and therefore with the tape, during the operations 10 of cutting.

[0033] According to a further refinement, the te- This cutter is equipped with a group of punches having different dimensions in the y direction between at least two of the group's punches and the punching of the 15 tape that will be wrapped to build the armor av- will be using different punches in different por- tape actions. This way it will be possible to react to create radial grooves having width differences in function of the radial coordinate of the throat itself. 20

[0034] A practical case, not limiting and already here described, is shown in figure 4b, where it can be easily mind observe the two bevels 43' and 43'' (but they are further conformations are also possible, for example with only one of the two chamfers) in the radial parts 25 more external and internal of the throat. This variant con- feels advantageously to obtain greater armor mind compatible with conductor windings electric that will be housed in the throats and wrapped in the armor zone between two consecutive grooves, re- 30 thus being more adherent in proximity to the chamfering areas where the electrical conductor is curved.

[0035] An armor made in this way constitutes also the subject of the present invention.

[0036] The additional features and refinements names are the subject of the subclaims.

[0037] The characteristics of the invention and the advantages 5 consequences resulting from it will be more easily achieved from the following detailed description of the fi- attached figures, in which: - Fig. 1 shows an example of a system for the manufacturing of electric motor armatures. 10 - Fig. 2 shows a single cutting line (Fig. 2a) and double (Fig. 2b) made on a ribbon of virgin sheet metal. - Fig. 3a and 3b show the obtained armatures from the wrapping of the ribbons of the previous figures 15 teeth. - Fig. 4 shows a plan view of two tapes shaped with constant and variable width of the openings and the corresponding throat profiles of the obtainable armors. 20 - Fig. 5 shows an axonometric view of a cutting head according to an implementing form of the invention mounted on the press hammer of a cutting machine. - Fig. 6 shows a detail of the pre- 25 transferor with the punch matrix highlighted and the support sleds. - Figs. 7 and 8 show a schematic section of the head of the previous figures according to two planes orthogonal to the support plate of the 30 head. - Figs. 9 and 10 show the cross-sections of the figures precedents in an implementing form of the inven- tion. - Figs. 11-13 show schematically the translation head movement in the x-direction for selection tion of one of the three punches of a punch line zones. 5 - Fig. 14 shows an enlargement of Fig. 11 with the distances in play between punches highlighted and cutting tape. - Fig. 15 shows two views of an embodiment in which there is a mechanism for translation 10 axial of the cutting head so as to allow- pull the punch distance adjustment work from the tape before the punching operation nature. - Fig. 16 shows a detail of a matrix 15 of movable wall mold to receive punches of different size during the trans- operation ciatura. - Fig. 17 shows the position in axonometry of the mold matrix with respect to the selected punch 20 tion in an embodiment of the invention.

[0038] The cutting head of the present invention tion can be used in any ta- son of a sheet metal where it is necessary to make a 25 quick change of punches.

[0039] In the field of armor manufacturing of engines / alternators the invention finds, however, the its most significant application. In this sector it is, in fact, necessary to replace with a certain fre- 30 quenza the worn punches as well as make cuts of variable width on a ferromagnetic tape to be used to create a winding, in particular stator, which has chamfers on the armatures. For for this reason the invention will be mainly de- written with reference to this application without this should be considered limiting of the scope of protection of the same. 5

[0040] With reference to Fig. 1, a system for the construction of armatures for electric motors takes a source warehouse 1 which is loaded with a reel containing a known quantity of tape virgin thallic acid 9 which is processed inside the plant 10 passing through various stations until you get the desired armature wound on a collection spool 4.

[0041] What is of interest here is the part of the im- plant responsible for making carvings on the ribbon 15 before winding it onto the collection reel 4.

[0042] This part, identified with the reference 2 in the figure, is a punch cutting machine 3 in the which at least one single cut is performed 90 (fi- figure 2a) or double 90' ​​and 90'' (figure 2b) on the tape 20 virgin 9 according to a predefined form so such as to form a band of shaped ribbon 91 or 91';

[0043] The shaped ribbon band is formed in a way such that, when wrapped, it can constitute the arma- ture 4 shown in figures 3a or 3b. 25

[0044] Figure 4 shows two possible realiza- tions of a stator armature of a flux motor axial according to a front view of portions of the same. The winding is shown on the right while on On the left is shown a portion of the tape from which such 30 windings were achieved.

[0045] As you can see, the radial grooves 42, 42' they develop with a substantially parallel shape lepiped, whose cross-section corresponds to the shape of the grooves 95, 95' that the cutting punch im- first on blank tape 9.

[0046] In the case of Fig. 4a, since the openings 95 have a constant width d, you get an arma- 5 ture with sharp edges 43.

[0047] In the case of Fig. 4b, however, since the Openings 95', 95'', 95''' have a variable width d , d , d , we get an armature with rounded edges 1 2 3 data 43', 43''. Specifically, it has been increased 10 the width of the grooves in the sections of tape that go to form a certain number of radially internal turns and / or radially external in the terminal part (external and / or internal) of the coils according to a known progression such as to generate a fillet in the sharp edges 15 dially more internal 43 and / or radially more external 43'' of armor throats, with radius of connection R predetermined. For illustrative purposes the repre- tion of the throats is not necessarily in proportion and to scale with possible stator designs; 20 in particular, the following have been expanded and exacerbated: size of the cuts and reduced the distance between a ta- son and the other.

[0048] By varying the size of the punches of tran- ciatura 3 it is also possible to create dif- 25 references between throat and throat of the same armor and / or differentiated and easily usable profiles for the production of different types of armour, for example of different size or with a different number of scales nature, limiting, if not eliminating, the operations 30 of equipment in the machine.

[0049] Let's now look at the characteristics in detail. that of the cutting machine and its operation.

[0050] This is basically a press with hammer with vertical movement along the z direction (fi- figures 5 and following) equipped with a cutting head 10 punch 3. The tape 9 runs in a y direction lying on a plane transversal to the z direction in 5 so that the punch 3 in its reciprocating stroke high / low encounters tape 9 near a counter-mold 5 below, known in jargon as matrix. The countermould 5 has a support surface for the tape in which an opening is provided to receive 10 the punch 3 at the end of the stroke. We will see in more detail forward the characteristics of this component.

[0051] Since there is a need to operate a fast change of the cutting punch, implementation forms of the in- invention foresees equipping the head 10 with a plurality 15 ity of punches 3 that can be selected for to make cuts with desired shapes and dimensions installments.

[0052] One solution could be to use to develop a pneumatic system that controls singularly 20 mind each punch of the plurality so as to expose the working one in the z-direction of shearing- ture. This would make the system very complex and co- stoso. For this reason the inventors turned to to actuator-free solutions capable of controlling 25 the single punch.

[0053] According to the invention, a solution provides the use of a group of punches arranged side by side according to the z-direction of punching so as to for- sea ​​a matrix of m rows and n columns on a plane 30 transversal to the z direction. The rows and columns are not necessarily orthogonal, but can be however inclined towards each other. In an implemented form, the columns are parallel to the y-direction of sliding of the tape, while the lines are perpendicular colabili to these in the x direction so that the triplet x, y, z represent a triplet of a reference system Cartesian coordinate system. Other configurations are possible. 5 depending on the reference system used and de- the orientations of the individual elements.

[0054] With reference to Fig. 5, the trans- ciante 10 according to an embodiment of the invention comprises a support plate 11 suitable for being 10 fixed to the plate 100 of the cutting press- trice directly or through appropriate interfaces.

[0055] As best visible in Fig. 6, the punches, which in this example are 9, organized in a ma- 3x3 trice, have a cylindrical base with a shaped head 15 of parallelepiped and are mounted sliding axially piston-like in a support plate 12 equipped with corresponding holes. The support plate 12 is fixed to a first slide 13 capable of translating in the y-direction with respect to a second slide 14 a 20 in turn able to translate in the x direction re- respect to the support plate 100.

[0056] The translation of the two sleds is entrusted to a pair of actuators which, in the specific example shown in Fig. 5, are represented by two engines 25 electric with shafts coupled to worm screws.

[0057] The two motors position the set along x and y of punches in the default position for cutting- tape ture. In this embodiment, the movement ment occurs via recirculating screw and tail guides 30 of swallow to ensure greater compactness and pre- decision possible. This should not be considered li- imitative of other possible equivalent realizations.

[0058] Figs. 7 and 8 show, respectively, the translation along the x-direction and along the x-direction y of the punch matrix.

[0059] Advantageously, a mechanism is present cam that is able to bring a single cam closer to the tape 5 sets of punches while the other two remain distant started from the tape. This occurs by varying of the position of the sled along the y-axis as mo- layer in Fig. 8 and 10.

[0060] In particular, cam 131 raises a 10 sets of punches 3', 3'', 3''' oriented in the direc- tion x. This causes the slats to slide 132 in the seat of the slide 13. The strips 132, when the punches are not in contact with the cam, they are kept apart by springs 133. In this 15 way, to a translation of the set of punches in the di- y direction also corresponds to a translation in the di- z-direction of approach to the tape of an entire row of punches 3', 3''. 3'''.

[0061] The choice between the punches of the line takes place 20 translating the punch matrix in the other direction x so that the punch of interest is superimposed to the tape at the counter-mold 5 as shown in Fig. 11-13.

[0062] The choice to bring the punch closer to the tape 25 of interest using a double translation movement, combined with a kinematic mechanism, for example a cam, allows to avoid the use of complex pneumatic systems which act on the punches individually.

[0063] Since the tape can have a size 30 transverse greater than the distance between two punches belonging to the same line, it is possible to discon- rare that the nearest punch interferes with the tape scaling in the x-direction the heights of the punches. As can be seen from figures 11-13, the punches zones 3', 3'', 3'' have different heights. If, in this specific example, the translation in the x direction It happens from right to left, it is exposed towards 5 the tape only the lowest adjacent punch (3'' in Fig. 11, 3' in Fig. 12) compared to the working one.

[0064] In a refinement it is possible to adjust the distance of the punches in the z direction so as to avoid any unwanted contact between the punches 10 non-cutting and the sheet metal in the meantime the punch tran- ciante works.

[0065] Fig. 14 helps to understand this I look. If the punch set can also translate in the z direction, you can adjust the distance of the 15 punch group from the support plate 11 first to start the cutting operation so that, called s is the stroke of the cutting head, x is the distance of the working punch from the supporting surface and the difference in height between the working punch and the 20 adjacent smaller height punch belonging to the subgroup of punches selected by translation in the y direction, it turns out s <d in modo che detto pun- areas adjacent to the work area do not interfere with the support surface, and therefore with the tape, 25 during cutting operations.

[0066] If adjustment along the z-axis is available bile, the sequence of work phases for a backhoe loader of punches arranged according to a row of the matrix can be summarized as follows using as a reference 30 figures 11 to 13 already discussed: Phase 1 The 3''' punch cuts the sheet metal for a certain number of runs (Fig. 11). Phase 2 The x-axis positions the 3'' punch in work and the z-axis brings it closer to the tape at the working distance. The 3'' punch cuts the sheet metal for a certain 5 number of runs (Fig. 12). Phase 3 The x-axis positions the punch 3' in work and the z-axis brings it closer to the tape at the working distance. The 3' punch cuts the sheet metal for a certain 10 number of runs (Fig. 13).

[0067] Punching machines usually have a stroke of the punch adjustable according to the state of aff- punch spinning and sheet metal thickness, this happens in the vast majority of cases 15 remotely by the operator acting on the system control (the operator rarely intervenes manually) mind on the machine to adjust the stroke via ci- nematisms or other systems).

[0068] In the theoretical variable stroke punching machines 20 ically, to ensure movement along the z-axis, it is can take advantage of the stroke adjustment system already present and no additional axis is required. In this case the quick change matrix can therefore be directly connected to the punch hammer- 25 trice going to implement a software function that adjusts the stroke width as required from the application, acting at the programming level in the existing machine.

[0069] For all other cases, where there is no 30 a stroke adjustment mechanism or gear change of the punch stroke is too complicated / slow, it is it is possible to implement an additional electric axis as shown in Fig. 15.

[0070] In this case the support plate 11 of the punch matrix is ​​not directly connected- mind to the 100 mallet, but it is mounted smoothly and carried 5 at an appropriate distance from the conveyor belt via an electric axis 110. The electric axis 110, directly connected to hammer 100, going to move support 11 away / closer and, therefore, the punch matrix with respect to the hammer, performs the mo- 10 movement along the z-axis which ensures the correct di- clearance between punch and tape.

[0071] To avoid interference, in a perfect- ment it is expected that the countermould or matrix 5 is adapted to the width of the punch through a system 15 side wall opening adjustment 51, 52 consisting of a recirculating screw coupled with a 53 engine and two DX-SX threaded snails as shown in Fig. 16.

[0072] Fig. 17 shows the positioning of the point 20 zones 3' selected in correspondence with matrix 5 with walls 51, 52 axially adjustable so as to form- have a cavity capable of receiving the selected punch operated in its entirety.

[0073] A control unit (not shown in the 25 figures) underlies the operation of the system in ge- general, and of the punching machine in particular, setting the translations necessary to operate the selection of the work punch.

Claims

CLAIMS 1. Cutting head (10) for machines for cutting a metal strip for the production of armatures of electric motors, in particular axial flux, characterised by the fact that it comprises a support plate (11) of a plurality of punches (3) arranged parallel according to a first direction z so as to form a matrix mxn on a section plane perpendicular to said first direction z with m rows arranged according to a second direction x and n columns arranged according to a third direction y, in which the punches (3) are supported so as to be movable in the x direction, in the y direction and in the z direction so as to be able to select a punch Pij to be used for the cutting by translating the matrix of punches so that said punch P±j is exposed towards the surface of the strip (9) to be cut and at a certain distance from said strip,the punches (3) being constrained to move in groups in the z direction with respect to the support plate so that the translation in the z direction of approach of a punch P±j to the strip to be cut with respect to the support plate causes an entire row of punches Pi to approach the strip to be cut.

2. Head according to claim 1, further comprising a first actuator (15), a second actuator (16) and at least one cam (131), said first actuator (15) acting on a first slide (14) so ​​as to induce a translation of the punch matrix in the x-direction, said second actuator (16) acting on a second slide (13) so as to induce a translation of the punch matrix along the y-direction, the cam (131) being integral with the support plate (11) so that, during the translation along the y-axis of the matrix, the head of a punch, or of an element integral with it, interferes with the cam in the manner of a tappet inducing a translation along the z-axis of said punch and, consequently, of the row of punches to which said punch belongs.

3. Head according to claim 2, wherein the cam (131) is arranged in a median position so that the selection of a row of punches causes the translation of said row in the z direction in the vicinity of the central part of the head.

4. Head according to one or more of the preceding claims, wherein the punches belonging to the same row are scaled in height or have an extension in the increasing or decreasing z direction.

5. Head according to one or more of the preceding claims, comprising a third actuator (110) which acts on the support plate or on an element integral with it so as to induce a rigid translation of the plate (11) and, therefore, of all the punches, in the z direction so as to adjust the distance of the punches with respect to the strip to be cut (9).

6. A machine for cutting a strip comprising a support for a cutting head (10) according to one or more of the preceding claims and a press suitable for applying a pressure force on said support in a manner synchronised with the advancement of the strip (9) to be cut, the head being mounted so that the direction of the pressure force coincides with the z-direction of the punches and the strip runs in the y-direction.

7. A machine according to claim 6, comprising a control unit interfaced with the head actuators and configured to select a work punch by translating the punch matrix in the x and / or y directions relative to a counter die element (5) adapted to receive the selected punch in a cavity during the strip blanking operation.

8. Machine according to claim 7, wherein the counter-die element (5) extends longitudinally in the y-direction of sliding of the strip to be cut and transversely in the x-direction and has movable walls (51, 52) to adapt the longitudinal length of the counter-die cavity to the size in the y-direction of the selected punch.

9. Machine according to claim 7 or 8, wherein the control unit is configured to adjust the distance of the punches from the counter die before the blanking operation by driving the actuator (110) of the head suitable for translating the punch matrix in the z direction so that, where s is the stroke induced by the press on the head, x is the distance of the working punch from the counter die and the difference in height between the working punch and the punch of shorter length adjacent, on the same line, to the working punch is s <d in -23SKF-375244 modo che detto punzone adiacente a quello di lavoro non interferisca con il controstampo, e quindi con il nastro, durante le operazioni di tranciatura.

10. Machine according to claim 9, where said 1 is the width of the strip and Im is the width of the opening to be made on the strip, the control unit is configured to face the working punch to the strip so that the adjacent punch, arranged on the same line and facing the part of the strip of width 1-lm not facing the working punch, is of a lower height so that said punch adjacent to the working punch does not interfere with the strip during the blanking operation.

11. A method of blanking a metal strip for the production of armatures for electric motors, particularly axial flux motors, which method comprises: a) providing a blanking head equipped with a group of punches; b) positioning the strip on a die or a support surface equipped with an opening of variable dimensions suitable for receiving one of the punches during the blanking operation; c) selecting a punch from the group so as to expose said punch towards the strip to be blanked in correspondence with the opening of the support surface; d) varying the dimensions of the opening of the support surface as a function of the dimensions of the selected punch; -24SKF-375244 e) moving the blanking head alternately and synchronously with the movement of the strip so as to make sequential cuts on said strip of a size corresponding to the dimension in the y direction of the selected punch;wherein the punch selection occurs by moving the group of punches so as to cause the selected punch to be located in correspondence with the opening of the support surface and at a certain distance from said surface, the movement of the group of punches occurring in a first direction so as to select a subgroup of punches from the group of punches and in a second direction so as to select the desired punch from the subgroup of punches, the translation in the first direction inducing, by means of a cam device, a translation of said subgroup of punches in a third direction towards the support surface.; 12. A method according to claim 11, wherein the punches of the punch subgroups selectable from the punch group by translation in the first direction have scaled heights, the method providing for adjusting the distance of the punch group from the bearing surface before starting the blanking operation so that, where s is the stroke of the blanking head, x is the distance of the working punch from the bearing surface and x is the height difference between the working punch and the adjacent punch of lower height belonging to the punch subgroup selected by translation in the first direction, -25SKF-375244 is s <d in modo che detto punzone adiacente a quello di lavoro non interferisca con la superficie di appoggio, e quindi con il nastro, durante le operazioni di tranciatura.

13. Method according to claim 11 or 12, wherein: - in step a) a cutting head is provided equipped with a group of punches having dimensions in the y direction mutually different between at least two of the punches of said group of punches; - steps c), d), e) are repeated using two or more punches of the group of punches chosen according to a known and predefined order, choosing punches of dimensions in the y direction mutually different.

14. Electric motor armature made by winding a longitudinal portion of a cut strip according to claim 13 around a winding element.

15. Electric motor armature according to the previous claim, comprising a plurality of radial grooves (42') with edges connected in the radially outermost part (43') and / or radially innermost part (43'') with a predefined connection radius R, said armature obtained by winding a longitudinal portion of cut strip in such a way as to provide width of the slots in the sections of strip which form a certain number of radially innermost and / or radially outermost turns in the terminal part (external and / or internal) of the turns according to a known progression.