PLANT AND METHOD FOR MANUFACTURING FERROMAGNETIC CORES OF ELECTRIC MACHINES

Abstract

A plant (10) and a method are described for manufacturing ferromagnetic cores of electric machines formed by a plurality of laminations which are packed and joined together by gluing in a blanking/punching tool (15) to which a continuous metal laminate (11) of ferromagnetic material is fed. In addition to the blanking/punching tool, the plant comprises at least one unit (21) for applying an adhesive material to a surface of the continuous metal laminate, at least one unit (25) for applying an activating compound to the opposite surface of the continuous metal laminate and at least one control unit (22) for controlling the application of the adhesive material and the activating compound into the respective application units. The unit for applying an adhesive material to a surface of the continuous metal laminate comprises a printing device (23, 60) and at least one transfer element (28, 51) on which the printing device deposits the adhesive material according to one or more impressions of a shape corresponding to the outline of each of the laminations. The adhesive material is then applied by the at least one transfer element to a surface of the continuous metal laminate according to the outline of each lamination, which is defined by the impressions.

Claims

1. A plant for manufacturing ferromagnetic cores of electric machines, wherein each of said ferromagnetic cores is formed by a plurality of laminations which are packed in a blanking/punching tool to which a continuous metal laminate of ferromagnetic material is fed, said laminations being joined together by gluing, said blanking/punching tool comprising at least one blanking/punching station and at least one station for cutting and packing the laminations blanked from said continuous metal laminate, the plant comprising at least one unit for applying an adhesive material to a surface of said continuous metal laminate, at least one unit for applying an activating compound to the opposite surface of said continuous metal laminate and at least one control unit for controlling the application of said adhesive material and said activating compound into the respective application units, wherein said unit for applying an adhesive material to a surface of said continuous metal laminate comprises a printing device and at least one transfer element on which said printing device deposits the adhesive material according to one or more impressions of a shape corresponding to the outline of each of said laminations, said adhesive material being then applied by said at least one transfer element to a surface of said continuous metal laminate according to the outline of each lamination, defined by said impressions.

2. The plant according to claim 1, wherein said at least one transfer element for transferring the adhesive material to a surface of said continuous metal laminate comprises one or more pads each receiving one or more impressions of said adhesive material from a silk-screen printing device or from a flexo-printing device.

3. The plant according to claim 2, wherein said one or more pads are constrained to a cylindrical roller interposed between said printing device and said continuous metal laminate.

4. The plant according to claim 2, wherein said one or more pads are constrained to a closed belt which moves in a transverse direction with respect to the direction of travel of the continuous metal laminate, and wherein said printing device which deposits the adhesive material on said pads is arranged along the path defined by said closed belt.

5. The plant according to claim 1, wherein said printing device is a printing device which adopts a circular or rotary silk-screen printing technique.

6. The plant according to claim 1, wherein said printing device is a printing device which adopts a flat silk-screen printing technique or a flexography technique.

7. The plant according to claim 1, wherein said at least one unit for applying an activating compound to the opposite surface of said continuous metal laminate is combined with at least one chamber in which a depressurised condition is provided.

8. A method for manufacturing ferromagnetic cores of electric machines, wherein each of said ferromagnetic cores is formed by a plurality of laminations which are packed in a blanking/punching tool to which a continuous metal laminate of ferromagnetic material is fed, said laminations being joined together by gluing, said blanking/punching tool comprising at least one blanking/punching station and at least one station for cutting and packing the laminations blanked from said continuous metal laminate, the method comprising the steps of: a) advancing a continuous metal laminate of ferromagnetic material through a plant for manufacturing ferromagnetic cores of electric machines, which is fed with said continuous metal laminate; b) applying an adhesive material to a surface of said continuous metal laminate through at least one unit for applying said adhesive material controlled by at least one control unit of the plant for manufacturing ferromagnetic cores of electric machines; c) applying an activating compound to the opposite surface of said continuous metal laminate through at least one unit for applying said activating compound controlled by said control unit of the plant for manufacturing ferromagnetic cores of electric machines; wherein, in said step b), said adhesive material is deposited by a printing device on at least one transfer element according to one or more impressions of a shape corresponding to the outline of each of said laminations, said adhesive material being then applied by said at least one transfer element to a surface of said continuous metal laminate according to the outline of each lamination, defined by said impressions.

9. The method according to claim 8, wherein said adhesive material is applied to said continuous metal laminate before said continuous metal laminate reaches said station for cutting and packing the laminations blanked from said continuous metal laminate.

10. The method according to claim 8, wherein said one or more impressions of adhesive material, which are deposited on said at least one transfer element to be then applied to a surface of said continuous metal laminate, have the same outline as each of said laminations and reduced dimensions in the proximity of the edges that follow the geometry of each of said laminations to leave an area free of adhesive material in the proximity of said edges.

11. The method according to claim 8, wherein said at least one transfer element for transferring the adhesive material to a surface of said continuous metal laminate comprises one or more pads each receiving one or more impressions of said adhesive material from a silk-screen printing device or from a flexo-printing device.

12. The method according to claim 11, wherein said adhesive material is deposited by a circular or rotary silk-screen printing technique on said one or more pads and then applied to a surface of the continuous metal laminate.

13. The method according to claim 11, wherein said adhesive material is deposited by a flat silk-screen printing technique or a flexography technique on said one or more pads and then applied to a surface of the continuous metal laminate.

14. The method according to claim 8, wherein said activating compound is applied to the opposite surface of said continuous metal laminate by providing a depressurized condition in the proximity of the application area.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Further characteristics and advantages of the present invention will become clearer from the following description, made by way of non-limiting example with reference to the accompanying drawings, wherein:

[0044] FIGS. 1A and 1B show embodiments of a plant according to the present invention;

[0045] FIG. 2 shows the scheme of a unit for applying the adhesive material according to an embodiment of the present invention;

[0046] FIGS. 3-13 show various embodiments of a plant according to the present invention;

[0047] FIG. 14 depicts the contour of a metal lamination before applying the adhesive material;

[0048] FIG. 15A depicts the contour of a metal lamination after applying the adhesive material;

[0049] FIG. 15B is an enlarged view of a pole piece of the lamination shown in FIG. 15A;

[0050] FIGS. 16, 17A and 17B show another embodiment of a plant according to the present invention;

[0051] FIGS. 18, 19A and 19B show another embodiment of a plant according to the present invention;

[0052] FIG. 20A depicts an example of deposit of the adhesive material by the circular (or rotary) silk-screen printing technique;

[0053] FIG. 20B depicts an example of deposit of the adhesive material by the flat silk-screen printing technique;

[0054] FIG. 21 is an enlarged view which depicts the action of a flat doctor blade running on a silk-screen;

[0055] FIG. 22 shows a further example of deposit of the adhesive material by the flexography technique;

[0056] FIGS. 23-27 depict some examples of application of adhesive materials according to the prior art.

EMBODIMENTS OF THE INVENTION

[0057] FIG. 1A shows a general embodiment of a plant 10 for manufacturing ferromagnetic cores of electric machines. A continuous metal laminate 11 is fed from a reel 12 to a tool 15 for blanking/punching through a feeding unit 13. The continuous metal laminate 11 can be optionally passed through a calender 14 to carry out the yielding of the continuous metal laminate 11.

[0058] In the blanking/punching tool 15 according to the present invention, there are at least one unit 21 for applying an adhesive material to a surface of the continuous metal laminate 11, at least one unit 25 for applying an activating compound to the opposite surface of the continuous metal laminate 11. In the plant 10, there is also at least one control unit 22 for controlling the application of the adhesive material and the activating compound in the respective application units.

[0059] FIG. 1B shows an embodiment of a plant 20a in which the unit 21 for applying an adhesive material to a surface of the continuous metal laminate 11 and the unit 25 for applying an activating compound to the opposite surface of the continuous metal laminate 11 are placed outside the blanking/punching tool 15, e.g. downstream of the feeding unit 13 for feeding the continuous metal laminate (FIG. 1A) and upstream of the blanking/punching tool 15. The plant 20a comprises a unit 21 for applying an adhesive material, a control unit 22 and a unit 25 for applying an activating compound to the opposite surface of the continuous metal laminate 11.

[0060] The unit 25 is combined with a chamber 29 in which a depressurized condition is provided to prevent the dispersion of potentially harmful volatile compounds into the environment in which the personnel work. The unit 25 for applying an activating compound to the opposite surface of the continuous metal laminate 11 is sketched herein by a cylinder, but it should be pointed out that, here and hereinafter, the activating compound can also be applied by other means, e.g., nozzles which apply by spraying the activating compound to the opposite surface of the continuous metal laminate 11. In any case, in the plant 20a of FIG. 1B, the units 21 and 25 are released from the movements of the press in the blanking/punching tool 15.

[0061] In the embodiment of FIG. 1B, a station 16 for blanking the profiles of each lamination and a station 17 for cutting and packing the blanked laminations are also emphasised, both stations being included in the blanking/punching tool 15. In the station 16, the continuous metal laminate 11 is subjected to the blanking of the various profiles to define the geometries of the lamination and finally, as the last operation, the blanking of the outer contour of the geometry in the station 17 and the packing are carried out, with the consequent formation of the pack of laminations.

[0062] In the scheme of FIG. 2, an embodiment of a unit 21 for applying the adhesive material is shown. The unit 21 comprises a printing device 23 which deposits the adhesive material on a transfer element 28 which, in turn, applies the adhesive material to one face of the continuous metal laminate 11 according to one or more impressions of a shape corresponding to the outline of each of the laminations, and a contrast roller 24 in a position opposite the transfer element 28. The contrast (or counter-pressure) roller 24 has the purpose of supporting the continuous metal laminate 11 during the application of the adhesive material, by controlling its distance with respect to the transfer element 28.

[0063] This scheme shows a transfer element 28 consisting of a cylinder equipped with pads 19 made of or coated with e.g. an elastic material, such as rubber, natural rubber or the like, which receive the adhesive material from the printing device 23. The transfer element 28 can also consist of a cylinder with smooth surface, i.e. free of the pads 19, which is also made of an elastic material.

[0064] FIGS. 3 to 13 depict various embodiments with regard to the arrangement of the plant components. For example, in the plant 20b of FIG. 3, the unit 21 applies the adhesive material to the lower face of the continuous metal laminate 11, while the activating compound is applied by the unit 25 to the upper face of the continuous metal laminate 11.

[0065] In the plant 20c of FIG. 4, the activating compound is applied by the unit 25 to the lower face of the continuous metal laminate 11 outside, and upstream, of the blanking/punching tool 15, while the adhesive material is applied by the unit 21 to the upper face of the continuous metal laminate 11 inside the blanking/punching tool 15.

[0066] The plant 20d of FIG. 5 also has the unit 25 placed outside, and upstream, of the blanking/punching tool 15 and the activating compound is applied to the upper face of the continuous metal laminate 11, while the adhesive material is applied by the unit 21 to the lower face of the continuous metal laminate 11 inside the blanking/punching tool 15.

[0067] In the plant 20e of FIG. 6, both units 21 and 25 are included inside the blanking/punching tool 15. The activating compound is applied by the unit 25 placed upstream of the unit 21 for applying the adhesive material to the lower face of the continuous metal laminate 11.

[0068] Also in the plant 20f of FIG. 7, both units 21 and 25 are included inside the blanking/punching tool 15. Upstream, the adhesive compound is applied to the upper face of the continuous metal laminate 11 by the unit 21, while downstream, the activating compound is applied by the unit 25.

[0069] In the plant 20g of FIG. 8, the unit 21 for applying the adhesive material is placed outside the blanking/punching tool 15 and applies the adhesive material to the upper face of the continuous metal laminate 11, while the unit 25 for applying the activating compound is placed inside the blanking/punching tool 15 and applies the activating compound to the lower face of the continuous metal laminate 11.

[0070] The plant 20h of FIG. 9 is similar to that of FIG. 8, with the difference that the activating compound is applied by the unit 25 to the upper face of the continuous metal laminate 11, while the adhesive material is applied to the lower face of the continuous metal laminate 11 by the unit 21.

[0071] In the plant 20i of FIG. 10, the blanking/punching station 16 is separated from the subsequent station 17 for cutting and packing the laminations separated from the continuous metal laminate 11. The unit 21 for applying the adhesive material and the unit 25 for applying the activating compound are arranged between the stations 16 and 17. The same applies to the plant 20j of FIG. 11. In the plant 20i of FIG. 10, the unit 21 for applying the adhesive material is placed upstream of the unit 25 for applying the activating compound, while in the plant 20j of FIG. 11, the unit 25 is placed upstream with respect to the unit 21. In both plants 20i and 20j, the adhesive material is applied to the upper face of the continuous metal laminate 11, while the activating compound is applied to the lower face of the continuous metal laminate 11.

[0072] Also in the plant 20k of FIG. 12, the blanking/punching station 16 is separated from the subsequent station 17 for cutting and packing the laminations separated from the continuous metal laminate 11. The unit 21 for applying the adhesive material and the unit 25 for applying the activating compound are arranged between the stations 16 and 17. The same applies to the plant 20l of FIG. 13. In the plant 20k of FIG. 12, the unit 21 for applying the adhesive material is placed upstream of the unit 25 for applying the activating compound, while in the plant 20l of FIG. 13, the unit 25 is placed upstream with respect to the unit 21. In both plants 20k and 20l, the adhesive material is applied to the upper face of the continuous metal laminate 11, while the activating compound is applied to the lower face of the continuous metal laminate 11.

[0073] FIG. 14 shows by way of example the outline of a lamination 40, which will constitute the rotor of an electric rotary machine, before applying the adhesive material, while FIG. 15A shows the same outline of a lamination 40 after applying the adhesive material.

[0074] FIG. 15B depicts an enlarged view of a pole piece 41 of the lamination of FIG. 15A. As can be seen, the adhesive material A can be applied to a large part of the surface of the lamination 40 according to the outline and geometry of the same lamination, with the exception of an area 43 free of adhesive material in the proximity of the edges.

[0075] FIGS. 16, 17A and 17B show an embodiment of a plant 50 in which the adhesive material A is deposited on transfer elements, such as e.g. rubber or natural rubber pads 51, which are fastened to a closed belt 52. A printing device 23 or 60 deposits the adhesive material on the pads 51. The printing device 23 or 60 can be, e.g., a circular or rotary silk-screen printing device (FIG. 20A), or a flat silk-screen printing device (FIG. 20B) or a flexo-printing device 60 (FIG. 22).

[0076] This embodiment allows to achieve a decoupling of the unit for applying the adhesive material with respect to the speed or position of the continuous metal laminate 11.

[0077] The blanking/punching tool 15 is crossed by the belt 52 where the various rubber or natural rubber pads 51 are arranged. In the plant 50, the printing device 23 or 60 can continuously deposit the adhesive material on the pads 51. In the plant 50, between one pad 51 and the other, there is air and, therefore, the printing device 23 or 60 can always be in motion.

[0078] The belt 52, on which the pads 51 are mounted, will have a loop of suitable length, in such a way as to allow the screen 26 to work continuously, and will move in synchronism with the cycle of the press that operates the blanking/punching tool 15. When a pad 51, on which the adhesive material has been deposited, is in the proximity of the continuous metal laminate 11, a presser 55 presses the pad 51 on the continuous metal laminate 11, thus transferring the adhesive material from the pad 51 to the continuous metal laminate 11.

[0079] The activating compound can be applied to the opposite face of the continuous metal laminate 11 by a unit 25 such as that already described in the preceding embodiments.

[0080] The embodiment of the plant 70 shown in FIGS. 18, 19A and 19B is similar to that of FIGS. 16, 17A and 17B, with the difference that the adhesive material is applied to the lower face of the continuous metal laminate 11, while the activating compound is applied to the upper face of the lamination. The pads 51 are then mounted outside the belt 52. The printing device 23 or 60 is arranged along the path defined by the belt 52. A possible presser (not shown) is embedded in the lower part of the blanking/punching tool 15.

[0081] FIGS. 20A and 20B show some silk-screen printing techniques that can be adopted by a printing device 23. The printing device 23 of FIG. 20A is sketched here in the form of a circular or rotary silk-screen printing device, i.e. a printing device equipped with a circular or rotary cylindrical silk-screen 26. The cylindrical screen 26 can be made, e.g., of metallic, synthetic, natural material, etc. The amount of adhesive material distributed by a silk-screen depends on the type of screen adopted. The weft of the screen (number of threads and diameter of the same) allows to have wide flexibility in terms of amount and thickness of adhesive deposited. The deposition of the adhesive material on the transfer element 28, which can be a smooth-surface cylinder, a pad 19 or a pad 51, is caused by the pressure exerted by a flat doctor blade 27 and the centrifugal force. More precisely, from a theoretical point of view, the silk-screen should never touch the transfer element 28, 19 or 51.

[0082] The adhesive material is fed into the printing device 23 through a suitable pump and forced between the meshes of the screen 26 through the pressure exerted by the flat doctor blade 27, also in combination with the centrifugal force acting on the screen 26 during its rotation.

[0083] FIG. 20B depicts the flat silk-screen printing technique. This technique can be used e.g. in the step of stopping between one translation and the other of the continuous metal laminate 11. Also in this case, a flat doctor blade 37 is used which acts in translation on a silk-screen 36 to press the adhesive material through the open meshes of the silk-screen 36. For example, the meshes of the silk-screen 36 are open next to at least one impression 30 which has a shape corresponding to the outline of each of the laminations to deposit the adhesive material on each of the transfer elements 28, 19 or 51. The adhesive material is thus applied according to the outline 31 of each lamination.

[0084] The silk-screen printing technique is also depicted in the enlarged scheme of FIG. 21, in which the flat doctor blades 27, 37 are emphasised which press the adhesive material A through the open meshes of each silk-screen 26, 36 to deposit it on the surface of the continuous metal laminate 11.

[0085] According to the silk-screen printing technique, as depicted schematically in FIG. 21, it is the drop of adhesive material A which, retained by the screen, migrates from the silk-screen 26 or 36 to the transfer element 19, 28 or 51 under the effect of the pressure exerted by the flat doctor blade 27 and, in the case of circular or rotary silk-screen printing, also under the effect of the centrifugal force of the cylindrical silk-screen 26 during its rotation.

[0086] FIG. 22 shows an alternative embodiment to silk-screen printing for depositing the adhesive material on a transfer element 19, 28 or 51. In this embodiment, the printing device is a device 60 adopting a flexography technique.

[0087] Unlike the rotary silk-screen printing, which uses a single cylindrical screen fed therein with the adhesive material, the device 60 comprises a feeding tray 61 filled with adhesive material. A first roller 62 draws the adhesive material from the tray 61 and deposits it on an anilox-type roller 63, which in turn deposits the adhesive material on a rotary rubber plate 64. The plate 64 then deposits the adhesive material by contact on a transfer element 19, 28 or 51. A flat doctor blade 66 allows the excess adhesive material to be removed from the anilox-type roller 63.

[0088] Various changes can be made to the embodiments described herein without departing from the scope of the present invention, determined by the following claims. Geometric shapes and materials may differ from those shown so far schematically by way of example.