Patent Application
20230396136
The present invention relates to a plant and a method for manufacturing ferromagnetic cores of electric machines, consisting of packs of laminations and, in particular, of ferromagnetic cores composed of a plurality of laminations which are packed and joined together by gluing.
It is known in the art to make ferromagnetic cores of electric machines, e.g. electric motors, by stacking a plurality of metal laminations which are packed and fastened together mechanically, e.g. by crimping s formed during the blanking/punching working.
Techniques for mutual fastening of the laminations by gluing are also known. Patent application no. US2015097463A1 describes, as an example, various methods for making packs of metal laminations joined together by gluing, wherein the adhesive material is deposited through spraying techniques by nozzles on a surface of a continuous metal laminate fed to the blanking/punching tool, while an activating agent is deposited on the opposite surface of the metal laminate.
Basically, as shown e.g. in
In addition to the embodiments in which spraying techniques are used for applying the adhesive material, this document also suggests an application technique using a rubber-coated roller capable of applying the adhesive material to the lower surface of the continuous metal laminate. An auxiliary roller is placed at a minimum distance from the rubber-coated roller to regulate/dose the amount of adhesive material that is transferred to the rubber-coated roller and, consequently, the thickness of the adhesive material applied to the continuous metal laminate.
In any case, the embodiments described in US2015097463A1 do not suggest using well-defined impressions to apply the adhesive material to the metal laminate. In case of using spraying techniques, it is not possible to delimit any impression of the adhesive material applicable to the continuous metal laminate, while in case of application through a rubber-coated roller only some areas are delimited in which the adhesive material does not need to be applied to the continuous laminate; these areas are delimited by recesses formed on the rubber-coated roller and can accumulate adhesive material which can overflow from the recesses and compromise the uniform distribution of the adhesive material on the continuous laminate, thus compromising the correct regulation of the adhesive material thickness on the continuous laminate. When each lamination is blanked and then packed to an underlying lamination, the adhesive material can overflow from the ferromagnetic core being formed. The spillage of adhesive material can lead to functionality problems in the tool (e.g. seizures), quality problems in the pack of laminations forming a ferromagnetic core, e.g. shape tolerances not respected, and cleaning problems in the blanking/punching tool.
DE102018110951A1 describes a method and a plant for making ferromagnetic cores composed of laminations glued to each other. In this document, it is specified that the adhesive can be applied by means of spraying techniques, by interposing in any way masks, or by printing processes, such as e.g. silk-screen printing and flexography. However, the printing techniques described in this document do not take into account the fact that the adhesive must be applied to a metal laminate which, by its nature, can have any variations in thickness, any burrs generated during the previous blanking or rolling steps, any impurities or foreign bodies. All these drawbacks can affect the correct distribution of the adhesive on the moving metal laminate or even cause damages to the adhesive application units by means of the mentioned printing processes.
Moreover, none of these prior documents takes into account the fact that the adhesive materials used and any activating compounds can be harmful to the health of the operators working in the environments in which the plants for manufacturing ferromagnetic cores by gluing are installed.
This being stated, it is a task of the present invention to provide an improved plant and method for manufacturing ferromagnetic cores formed by a plurality of packed laminations and joined together by gluing for applications in electric machines.
Within this task, an object of the present invention is to provide a plant and a method of the type identified above which allow to manufacture ferromagnetic cores formed by packs of laminations joined together by gluing in which precision and repeatability are ensured in the application of adhesive material to the laminations also at very high cycling speeds.
Another object of the present invention is to provide a plant of the type identified above, which is versatile and can be easily adapted to the different requirements for manufacturing ferromagnetic cores, both by applying the adhesive material to the outside of a blanking/punching tool and inside the same blanking/punching tool.
A further object of the present invention is to provide a plant and a method of the type identified above, which are capable of ensuring a high precision of positioning of the adhesive material on the continuous laminate, in particular, by avoiding spillages of adhesive material outside the pack of laminations which form each ferromagnetic core.
Yet another object of the present invention is to provide a plant and a method of the type identified above, which allow to maximize the area of application of the adhesive material to the continuous metal laminate according to the outline of each lamination.
Yet another object of the present invention is to provide a plant and a method of the type identified above, which allow to ensure the uniformity of thickness of the adhesive material applied to the continuous metal laminate according to the outline of each lamination.
Yet another object of the present invention is to provide a plant and a method of the type identified above, which allow to compensate any irregularities and/or malformations of the metal laminate on which the adhesive material needs to be applied.
These and other objects are achieved by the present invention which concerns a plant according to claim 1 for manufacturing ferromagnetic cores of electric machines, wherein each of the ferromagnetic cores is formed by a plurality of laminations which are packed and joined together by gluing in a blanking/punching tool. Further peculiar characteristics of the present invention are set forth in the respective dependent claims.
A plant object of the present invention is used for manufacturing ferromagnetic cores of electric machines. Each of the 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. The laminations are joined together by gluing. The blanking/punching tool comprises at least one blanking/punching station and at least one station for cutting and packing the laminations blanked from the continuous metal laminate. The plant further comprises at least one unit for applying an adhesive material to a surface of the continuous metal laminate, at least one unit for applying an activating compound to the opposite surface of the continuous metal laminate and at least one control unit for controlling the application of the adhesive material and the activating compound into the respective application units.
In an embodiment of the present invention, the unit for applying an adhesive material to a surface of the continuous metal laminate comprises a printing device and at least one transfer element 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.
The transfer element, which is put into direct contact with the continuous metal laminate to apply the adhesive material thereto, allows to absorb any irregularities of the continuous metal laminate, such as e.g. variations in the thickness of the continuous metal laminate which can compromise the correct application of the adhesive material on the continuous metal laminate.
Moreover, the presence of the transfer element allows to avoid damages to the unit for applying the adhesive material and, in particular, to the printing device, in case the continuous metal laminate has burrs, damages or any foreign bodies.
A distribution of the adhesive material with uniform and repeatable thickness is thus achieved on each of the laminations, which will then be blanked from the continuous metal laminate and packed on the underlying laminations in the station for cutting and packing of the laminations.
In an embodiment, the at least one element for transferring the adhesive material to a surface of the continuous metal laminate comprises one or more pads each receiving at least one impression of the adhesive material from a silk-screen printing device or flexo-printing device.
In an embodiment, the pads are constrained to a cylindrical roller interposed between the printing device and the continuous metal laminate.
In another embodiment, the pads are constrained to a closed belt which moves in a direction transverse with respect to the direction of travel of the continuous metal laminate. The printing device, which deposits the adhesive material on the pads, is arranged along the path defined by the closed belt.
This solution allows to decouple the advancement of the continuous metal laminate with respect to the steps of depositing the adhesive material on the various pads.
According to a possible embodiment, the printing device is a printing device which adopts a circular or rotary silk-screen printing technique.
In other embodiments, the printing device can be a printing device which adopts a flat silk-screen printing technique or a flexography technique.
In an embodiment, the at least one unit for applying an activating compound to the opposite surface of the continuous metal laminate is combined with at least one chamber in which a depressurized condition is applied.
The invention further relates to a method for manufacturing ferromagnetic cores of electric machines, wherein each of the 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. The laminations are joined together by gluing. The blanking/punching tool comprises at least one blanking/punching station and at least one station for cutting and packing the laminations blanked from the continuous metal laminate. According to a possible embodiment, the method comprises the steps of:
According to a possible embodiment of the present invention, in step b) the 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 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.
In an embodiment of the method, the adhesive material is applied to the continuous metal laminate before the continuous metal laminate reaches the station for cutting and packing the blanked laminations from the continuous metal laminate.
According to an embodiment of the method, the impressions of adhesive material, which are deposited on the at least one transfer element to be then applied to a surface of the continuous metal laminate, have the same outline as each of the laminations and reduced dimensions in the proximity of the edges that follow the geometry of each of the laminations, in such a way as to leave an area free of adhesive material in the proximity of the edges. This allows to apply the adhesive material in such a way as to prevent the adhesive material from overflowing from the pack of laminations in the ferromagnetic core achieved as a finished product. The impressions can however be adapted with particular shapes depending on the various manufacturing requirements, such as e.g. to create areas without deposit of adhesive material, which act as containment tanks for the excess adhesive material.
In an embodiment of the method, the at least one element for transferring the adhesive material to a surface of the continuous metal laminate comprises one or more pads each receiving one or more impressions of the adhesive material from a silk-screen printing device or flexo-printing device.
In particular, the adhesive material is deposited by a circular or rotary silk-screen printing technique on one or more pads and then applied to a surface of the continuous metal laminate.
In other embodiments, the adhesive material can be deposited by a flat silk-screen printing technique or a flexography technique on one or more pads and then applied to a surface of the continuous metal laminate.
According to an embodiment of the method of the present invention, the activating compound is applied to the opposite surface of the continuous metal laminate by providing a depressurized condition in the proximity of the application area. This allows to prevent, or in any case limit, the dispersion into the environment of any harmful vapours which can be harmful to the operators and which can also pollute the adhesive material applied to the continuous metal laminate.
It has been found that a transfer element interposed between a printing device, which deposits the adhesive material, and the continuous metal laminate allows the absorption of any variations in the thickness of the metal laminate which can have influence on the distribution of the same adhesive. Moreover, by interposing a transfer element between the printing device and the metal laminate, the printing device is protected from the presence of possible impurities on the laminate, burrs due to the process of blanking or rolling and cutting of the continuous metal laminate (coil), and the presence of any foreign bodies.
A further advantage given by the interposition of a transfer element is represented by the possibility of being able to regulate the application pressure of the adhesive material with greater precision, thus allowing a more precise and regular application of the adhesive material to the metal laminate, especially in the proximity of the cutting edges of each lamination. Moreover, the solution proposed with the present invention allows an extremely precise dosage of the adhesive material, thus avoiding waste of the adhesive material used.
Thanks to the plant and the method according to the present invention, it is possible to achieve ferromagnetic cores of electric machines in which the adhesive material and the activating compound, which are applied to the laminations, once put into contact with each other, do not protrude from the pack of laminations, which forms the ferromagnetic core achieved as a finished product.
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:
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.
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
In the embodiment of
In the scheme of
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.
In the plant 20c of
The plant 20d of
In the plant 20e of
Also in the plant 20f of
In the plant 20g of
The plant 20h of
In the plant 20i of
Also in the plant 20k of
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.
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.
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.
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.
The embodiment of the plant 70 shown in
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.
The silk-screen printing technique is also depicted in the enlarged scheme of
According to the silk-screen printing technique, as depicted schematically in
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.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102020000022621 | Sep 2020 | IT | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/IB2021/058674 | 9/23/2021 | WO |
