Manufacturing method for lamella packs.

Abstract

For the manufacture of lamella packs, lamellae are cut from a flat-surfaced starting product (1), and these are stacked to form a lamella pack. Inside the lamella packs, the lamellae are bonded together by means of an adhesive. A high-temperature resistant cyanoacrylate adhesive is used as the adhesive. This is applied to the wetting layer (14) for the adhesive. The wetting layer (14) is adjusted to have a pH value in the range of >7. The high-temperature resistant cyanoacrylate adhesive can be distributed on the wetting layer (14) in such a way that good wetting is achieved, thus establishing a secure and fast bond between the lamellae.

Description

[0001] The invention relates to a method for producing lamellar packages according to the preamble of claim 1.

[0002] Electrical machines frequently use laminated cores made of stacked laminations, which are produced from cut electrical steel sheets or strips. A stamping press with a die or a laser cutting machine is typically used to cut the laminations. The electrical steel sheets / strips as starting materials are usually coated with a thin electrical insulating layer, with a thickness in the micrometer range. These insulating layers consist of organic or inorganic material. Hybrid coatings, composed of both organic and inorganic components, are also used. The electrical insulating layers are coated with lacquers that are formulated to have a positive effect on the cutting and stacking processes.

[0003] Laminate stacks are used for stators and rotors of electrical machines, such as electric motors or generators. To ensure that the overlapping laminations within the stack are firmly bonded, it is common practice to bond them using an adhesive. However, the electrical insulation layers can sometimes prevent a secure bond between the overlapping laminations. This can also extend the adhesive's curing time. For example, in a stamping machine, this affects the stroke rate, as it depends on the adhesive's setting time.

[0004] In a known method (EP 2 897 254 A2), the overlapping lamellae within the lamella pack are joined together using an adhesive. How the bond between the overlapping lamellae is achieved is not described.

[0005] It is also known (JP S60 18560 A) to apply an adhesive to the surface of a product.

[0006] The invention is based on the objective of designing the generic method in such a way that a reliable adhesive bond between the lamellae within the lamella package is ensured, whereby the reaction time of the adhesive should be as unaffected as possible by the starting material used for the lamellae.

[0007] This problem is solved according to the invention in the generic method with the characterizing features of claim 1.

[0008] In the process according to the invention, a wetting layer is applied to the flat starting material, which can be electrical tape or electrical steel. This layer ensures that the high-temperature-resistant cyanoacrylate adhesive can spread across the wetting layer in such a way as to achieve good wetting. It ensures a secure and rapid bond between the laminations. The wetting layer is adjusted so that its pH value is greater than 7, i.e., in the alkaline range, and the hydroxyl (HO) content in the wetting layer is sufficiently high. This ensures that the setting time or reaction time of the adhesive can be kept short. If, for example, a die-cutting device is used to cut the laminations, very high stroke rates can be achieved due to the short reaction times of the adhesive, allowing the die-cutting device to operate at high performance.High-temperature resistant cyanoacrylate adhesives include, in particular, ethyl and allyl cyanoacrylates.

[0009] The wetting layer consists of dipropylene glycol, distilled and / or demineralized and / or deionized water. This composition of the wetting layer has the further advantage of acting as a lubricant during the cutting process. It reduces wear on the die-cutting tool, thus extending its service life.

[0010] Furthermore, such a wetting layer has the additional advantage of protecting the starting product from corrosion.

[0011] The wetting layer is provided on an electrical insulating layer, which covers the lamella and is present on both sides of the starting product.

[0012] The wetting layer contains between approximately 30 and 75 wt% distilled and / or demineralized and / or deionized water and approximately 25 to 70 wt% dipropylene glycol. The proportion of water allows the pH value of the wetting layer to be easily adjusted to the respective application, ensuring that the adhesive always reacts reliably and flawlessly within very short times.

[0013] Aqueous solutions are alkaline when the concentration of hydroxide ions (OH⁻) exceeds that of hydronium ions (H₃O⁺). The pH value is then greater than 7.

[0014] It is advantageous to use only distilled, demineralized, or deionized water for the wetting layer. If all types of water are used for the wetting layer, their total proportion should be within the specified range of approximately 30 to 75% by weight.

[0015] In an advantageous embodiment, the wetting layer is applied to the starting product by spraying. This ensures that the wetting layer is applied evenly to the starting product. The starting product itself is not subjected to any stress in this process.

[0016] The wetting layer can also be applied to the starting product by brushing. Brushing allows the surface of the starting product to be cleaned to a certain extent, thus ensuring a reliable reaction between the wetting layer and the adhesive.

[0017] The wetting layer can also be applied to the starting product by polishing.

[0018] By using a solid additive, such as diamond, in the liquid, the surface can be smoothed by polishing or brushing. In an advantageous process, only the surface peaks of the insulating layer are removed at the micro level. The insulating effect of the insulating layer is maintained.

[0019] It is advantageous if the wetting layer is applied to the entire surface of the base product. This ensures that the entire base product is covered by the wetting layer, guaranteeing optimal corrosion protection, excellent lubrication during the stamping process, and optimal wetting by the adhesive.

[0020] Applying the wetting layer to both sides of the flat base product ensures optimal corrosion protection. Furthermore, this allows the adhesive to be applied to either side of the base product.

[0021] In an advantageous embodiment, the wetting layer is applied to the starting product in the feed direction upstream of a punching device or a corresponding cutting device. The subsequent application of the adhesive can then be carried out easily and without hindrance from the application of the wetting layer. In particular, the corresponding application units for the wetting layer and for the adhesive can be designed with a simple structure, since they are arranged separately from each other.

[0022] It is also possible to apply the wetting layer to the starting product using at least one application unit located on a die-cutting tool. In this case, the system used to carry out the process can be built relatively compactly. Here, too, the wetting layer is applied first, before the adhesive is subsequently applied to the wetting layer.

[0023] The adhesive application unit can advantageously be integrated into the die-cutting tool. This is beneficial due to the adhesive's short reaction times, as only a short time is required between applying the adhesive and cutting out the lamella and arranging it on the lamella pack. This ensures that the adhesive only reacts when the lamella with the applied adhesive is pressed onto the lamella pack.

[0024] With regard to high cycle rates in the production of the lamellae, it is further advantageous if the adhesive and the wetting layer are applied to the lamella immediately before or after cutting it from the starting product.

[0025] For a ribbon-shaped starting product, an advantageous method involves applying the wetting layer to the starting product in the feed direction after coating and before winding it onto a reel. This has the advantage that only the adhesive needs to be applied during the cutting or die-cutting process.

[0026] In another advantageous method, when a ribbon-shaped starting product is used, the wetting layer is applied in the feed direction of the starting product before the ribbon is split.

[0027] Further features of the invention will become apparent from the further claims, the description and the drawings.

[0028] The invention will be explained in more detail with reference to some embodiments illustrated in the drawings. These show Figs. 1 to 3 each show schematic representations of various systems for carrying out the method according to the invention; Fig. 4 shows a schematic and enlarged view of a section through a lamellar pack located in a brake unit of a stamping device; Fig. 5 shows a section through a stamping device in the area of ​​the brake unit; Fig. 6 shows a highly enlarged view, both in section and top view, of an electrical steel strip or sheet provided on both sides with a wetting layer; Figs. 7 and 8 show a corresponding representation Fig. 6 A second embodiment of an electrical steel sheet or electrical strip, Fig. 9 in schematic representation, the electrical steel sheet or electrical strip according to the Fig. 7 und 8 in a stamping tool, the upper part of which assumes a starting position, Fig. 10 in a representation accordingly Fig. 9 The upper part of the tool in its final position, with a portion of the contact area between the wetting layer and a lower part of the tool shown greatly enlarged, Fig. 11 in a schematic representation of a device for applying a coating and a wetting layer to an electrical steel strip, Fig. 12 in a representation accordingly Fig. 11 a second embodiment for applying a wetting layer to an electrical tape.

[0029] Fig. 1 The schematic representation shows a device with which lamellae 2 are cut from an electrical strip 1 or an electrical sheet in a known manner ( Fig. 5 ). This is shown as an example. Fig. 5 a punch 3 of a punching device 11, with which the lamellae 2 are punched from the electrical strip 1. They are stacked in a shaft 4 of the punching device 11 to form a lamella pack 5. The shaft 4 extends through a die 6 of the punching device 11. In the shaft 4, a brake unit 7 is located in a known manner, which is ring-shaped and exerts a radial braking force 8 on the lamellae 2 or the lamella pack 5 in a known manner. This braking force is high enough that the punch 3 can press the punched-out lamella 2 onto the lamella pack 5 located in the shaft 4 with sufficient pressure so that the stacked lamellae 2 can be firmly joined together in a manner to be described later. Fig. 5 The figure shows, by way of example, that between adjacent lamellae 2 within the lamella pack there are 5 adhesive points 9, via which the overlapping lamellae 2 are firmly connected to each other.

[0030] In addition to the adhesive bond, the overlapping lamellae 2 can also be positively connected to each other, for example by means of raised sections pressed out of the lamella or partially punched-out tongues that engage in corresponding recesses or indentations of the respective adjacent lamella.

[0031] The laminated core 5 is used for the manufacture of rotors and / or stators of electric motors as well as generators.

[0032] As from Fig. 1 As can be seen, the electrical steel strip 1 is wound onto a reel 10, which is rotatable about its axis. The electrical steel strip 1 unwound from the reel 10 is guided through a straightening device (not shown), which straightens the electrical steel strip 1 for the subsequent punching process. After the straightening device, the electrical steel strip enters the punching device 11, in which the lamellae 2 are punched from the electrical steel strip 1 in the manner described.

[0033] Two or more electrical tapes 1 can be fed side by side into the punching device 11, so that the lamellae 2 can be punched out of the individual electrical tapes 1 simultaneously. Furthermore, it is possible to punch the lamellae 2 in the electrical tape 1 not only in one track, but also, for example, in two tracks.

[0034] The punching device 11 is equipped with one or more corresponding punching tools in the form of punches 3. The lamellae 2 punched by these tools enter the shaft 4 as described, into which they are pressed immediately after punching by the punch 3. The shaft 4 serves as the receptacle for the lamella stack 5. The braking unit 7 ensures that the edges of the lamellae 2 rest against the inner wall of the shaft 4, preventing them from falling out. With each punching stroke, the newly punched lamella 2 is pressed downwards onto the lamellae already in the shaft 4. A support punch (not shown) projects into the shaft 4, upon which the lamellae 2 are stacked to form the lamella stack 5.With each punching stroke, the support punch is moved downwards step by step, so that the punched lamella 2 can be moved downwards into the shaft 4 far enough that the next lamella 2 to be punched can be reliably pressed into the shaft 4.

[0035] When several electrical strips 1 are simultaneously fed through the punching device 11, it is advantageous if each electrical strip 1 is assigned a slot 4, so that several lamination packages can be stacked side by side in the punching device 11 at the same time. However, it is also possible to provide only one slot 4 in the punching device 11, into which the laminations 2 punched from different electrical strips 1 are conveyed by means of a transport device, for example a rotary unit, to the area above the slot 4 and then pressed into the slot 4. Such a transport device is particularly advantageous if the laminations 2 are punched out from an electrical strip 1 in adjacent tracks. Then the adjacent laminations 2 can be transported into the single slot 4 by such a transport unit.

[0036] Within the lamella pack 5, the overlapping lamellae 2 are firmly bonded together by an adhesive. In the exemplary embodiment according to Fig. 1 The adhesive is applied to the electrical tape 1 by means of an application unit 12 in a known manner before the lamellae 2 are punched. The adhesive can be applied to the electrical tape 1 in various ways, for example, contactlessly by spraying or by application using a roller, a cylinder, or the like. The adhesive can be applied to the electrical tape 1 over a surface, or only in spots or strips. Depending on the size of the lamellae 2, a different amount of adhesive is required to firmly bond the lamellae 2 together within the lamella pack 5. Preferably, the adhesive is applied to the electrical tape 1 in spots.

[0037] High-temperature resistant cyanoacrylate adhesives are used as bonding agents. Suitable adhesives include ethyl or allyl cyanoacrylates. These are solvent-free, cold-curing, one-component adhesives that polymerize rapidly and cure within a short time. These cyanoacrylate adhesives have a high temperature resistance of at least 130°C, preferably up to approximately 150°C and higher.

[0038] Allyl cyanoacrylate can withstand higher temperatures for short periods under low stress. After approximately two hours, the bond achieves a temperature resistance of up to 250°C. Ethyl cyanoacrylates can also be used for short periods at higher temperatures when the stress is lower.

[0039] The electrical steel strip, or also the electrical steel sheets used for the production of the lamellae 2, are provided with a coating 13 ( Fig. 6 ), which forms an electrical insulating layer and is present on both sides of the electrical strip 1. The electrical insulating layers 13 have a very small thickness, in the micrometer range. The insulating layers 13 preferably consist of purely organic or purely inorganic materials. Hybrid coatings consisting of organic and inorganic components can also be used. Such insulating layers for electrical strips 1 or electrical sheets are known and are therefore not described in detail here. To form these insulating layers 13, lacquers are applied to the electrical strip 1, which can have different properties that have a positive effect on the cutting processes as well as the packaging or stacking of the laminations 2.

[0040] To ensure a secure bond between the overlapping lamellae 2 in the lamella assembly 5, the cyanoacrylate adhesive applies a wetting layer 14 to the insulating layer 13. This layer is designed to achieve good wetting with the cyanoacrylate adhesive, a surface pH > 7, and a predominance of OH⁻ in the water. Due to the good wettability of the wetting layer 14, the adhesive droplets do not form individual droplets but spread out across the surface of the layer. This ensures that the lamellae 2 within the lamella assembly 5 are securely and firmly bonded together.

[0041] The wetting layer 14 is formed in the embodiment according to Fig. 1 The coating is applied to both sides of the electrical steel strip 1 in the area between the reel 10 and the punching device 11 by means of a suitable application unit 15. The application can be carried out by spraying, brushing or polishing with the appropriate medium.

[0042] To produce the wetting layer 14, a lubricant containing dipropylene glycol and distilled and / or demineralized and / or deionized water is used. A preferred composition of the lubricant is: 30 to 75 wt% distilled and / or demineralized and / or deionized water, 25 to 70 wt% dipropylene glycol

[0043] Depending on the application, the lubricant may also contain polyglycol oil, the proportion of which can range from 0 to 20% by weight. If polyglycol oil is present in the lubricant, the proportion of dipropylene glycol and / or distilled and / or demineralized and / or deionized water can be reduced accordingly.

[0044] Suitable polyglycol oils include, in particular, polyethylene glycols (PEG), polyalkylene glycols (PAG), and polypropylene glycols (PPG). The pH of these polyglycols is alkaline, i.e., above 7. Since the pH of the wetting layer 14 is also alkaline, its good wettability allows not only for flawless bonding of adjacent lamellae 2, but also for a very short curing time. This enables high production volumes of lamellae 2 and lamella packs 5. Using the wetting layer 14 allows for curing times of approximately one second.

[0045] The additional lubricant also has further advantageous properties. For example, it can be used in the stamping process to increase tool life. Furthermore, the lubricant also serves to cool the stamping process.

[0046] The use of the described lubricant thus leads, in combination, to effective wear minimization of the stamping tools and to an improvement in energy efficiency in the stamping process due to the cooling effect.

[0047] The described lubricant is water-soluble, making it easy to handle. The wetting layer 14 also provides corrosion protection. The electrical tape 1 or the electrical steel sheet shows no corrosion even after weeks.

[0048] Furthermore, the described lubricant has an excellent viscosity index. Its viscosity decreases only slightly with increasing temperature, thus ensuring consistent properties even at higher temperatures.

[0049] The lubricant contains deionized or demineralized water as described. Completely demineralized water can also be used. Demineralized water can be easily obtained from ordinary tap water using ion exchangers.

[0050] When demineralized water is used as an additive to polyglycol oil, its purity is measured by its conductivity. The conductivity meters required for this purpose are well-known. The lower the conductivity, measured in S / cm or µS / cm, the fewer impurities the water contains.

[0051] To achieve optimal corrosion protection and excellent lubricating properties, the electrical steel strip 1 is advantageously covered over its entire top and bottom surfaces by the wetting layers 14. This surface application lubricates and cools the punching tool of the punching device 11. During the punching process, the wetting layer 14 is distributed over the cut surface of the electrical steel strip 1 or electrical sheet by the corresponding punching tool, thus protecting the cut surface against corrosion.

[0052] Fig. 7 und 8 The schematic representation shows wetting layers 14, which contain abrasives and fillers or solids 16, for example, diamond grains. The fillers 16 are distributed within the wetting layer 14. In addition to the described advantages of the wetting layer 14, the addition of the fillers 16 results in an optimization, i.e., a reduction of the surface roughness of the lamellae 2. This optimization or reduction occurs during the stamping process, as shown by the Fig. 9 bis 10 will be explained. In the embodiment according to Fig. 7 The fillers 16 protrude slightly above the wetting layer 14, whereas in the embodiment according to Fig. 8 are completely embedded in the wetting layer 14.

[0053] Fig. 9 Figure 1 schematically shows a guide plate of a tool upper part and a tool lower part 18 of the punching device 11. The two tool parts 17, 18 each have a flat pressure side 19, 20.

[0054] The electrical steel strip 1, or electrical sheet, with the wetting layers 14 provided on both sides, rests on the pressure side 20 of the lower tool part 18. The upper tool part 17 is spaced away from the electrical steel strip 1. It is moved downwards in the direction of arrow 21 (punching direction) towards the lower tool part 18.

[0055] The described guide plate of the upper tool part 17 can be provided in the stamping tool itself. However, it is also possible to provide the guide plate separately from the stamping tool in the stamping device 11.

[0056] In the procedure according to Fig. 1 The wetting layer 14 is applied to both sides of the electrical steel strip by the application unit 15 prior to the adhesive application. The additional lubricant, polyglycol oil, in the wetting layer 14 ensures that its good lubricating properties are utilized during all punching operations. The wetting layers 14 on both sides of the electrical steel strip 1 also guarantee a reproducible and reliable reaction of the cyanoacrylate adhesive due to the basic wetting layer 14. The cut surfaces created during the punching process on the electrical steel strip 1 are coated by the wetting agent as described, thus protecting these cut surfaces from corrosion.

[0057] While in the exemplary embodiment according Fig. 1 where the application unit 12 for the adhesive is provided on the die-cutting tool, in the embodiment according to Fig. 2 The application unit 15 for the wetting layer 14 is also provided together with the application unit 12 for the adhesive on the die-cutting tool. The application unit 15 applies the wetting layer 14 to both sides of the electrical tape 1, which is unwound from the reel 10. The wetting layer material 14 is applied before the adhesive is applied. This ensures that the cyanoacrylate adhesive can react reliably.

[0058] Fig. 3 Figure 1 schematically shows another embodiment in which the application of the wetting medium and the adhesive takes place within the brake unit 7 of the punching device 11. In this case, the wetting layer 14 is first applied to the punched lamellae 2, followed by the application of the adhesive. The wetting layers 14 provide a high level of corrosion protection, including for the cut surfaces created by punching the lamella. The cyanoacrylate adhesive can react reproducibly and reliably on the wetting layers 14. Fig. 3 The application units 12 and 15 for the adhesive and the wetting layer material are again only shown schematically. The electrical tape 1 is unwound from the reel 10.

[0059] Fig. 4 Figure 1 shows a schematic representation of the lamellar assembly 5 located within the brake unit 7. The brake unit 7 contains at least one cooling circuit 22, through which a cooling medium 23 is conveyed to cool the lamellar assembly 5. The cooling medium is located in a tank 24. Since the lamellar assembly 5 is formed in the brake unit 7 as described, sufficient time is available to cool the individual lamellae 2 and the lamellar assembly 5, and also to activate the cyanoacrylate adhesive. When the lamellar assembly 5 is removed from the brake unit 7, the lamellae 2 are firmly and securely connected to one another.

[0060] Fig. 11 Figure 1 shows a schematic representation of a device with which the wetting layer 14 can be applied to the electrical steel strip 1. The electrical steel strip 1 is delivered wound on a reel 10'. The electrical steel strip 1 is guided through a schematically represented straightening device 25, with which the electrical steel strip is straightened in a known manner. The electrical steel strip 1 then enters a coating plant 26, in which the coating 13 ( Fig. 6 The coating 13 is applied to both sides of the electrical steel strip 1. In the feed direction of the electrical steel strip 1, behind the coating unit 26, there is at least one application unit 15, with which the wetting layer 14 is applied to the coating 13 in the manner described. The application unit 15 is designed to apply the wetting layer 14 to both sides of the electrical steel strip 1. The electrical steel strip 1, with the coating 13 and the wetting layer 14, is then wound onto the reel 10. It is then moved to the punching device 11, with which the lamellae 2 are punched and stacked into the lamella pack 5 in the manner described.

[0061] Fig. 12 Figure 1 schematically shows a device in which the electrical steel strip 1 is unwound from the reel 10' and guided through a slitting unit 27. In contrast to the embodiment according to Figure 1, the electrical steel strip 1 is... Fig. 11The electrical steel strip 1 is already coated with the coating 13. In the feed direction, before entering the slitting unit 27, it is coated with the wetting layer 14 by means of at least one application unit 15. In the slitting unit 27, the electrical steel strip 1 is slit along its length in a known manner. The resulting electrical steel strips are coated on both sides, provided with the wetting layer 14, and are each wound onto the reel 10. The reel 10 is moved to the punching device 11, with which the lamellae 2 are punched and the lamella packs 5 are produced in the manner described.

Claims

1. A method for manufacturing lamella packets (5), in which lamellae (2) are cut out of a flat starting product (1) and stacked into a lamella packet, wherein the lamellae (2) in the lamella stack (5) are connected with each other by an adhesive, characterized in that the adhesive is a high temperature-resistant cyanoacrylate glue, which is applied to a wetting layer (14) for the glue, which is set in such a way that its pH value lies within a range >7 and consists of dipropylene glycol, distilled and / or demineralized and / or deionized water, and that the wetting layer (14) is provided on an electrical insulation layer (13), which covers the lamellae (2) and is present on both sides of the starting product (1).

2. The method according to claim 1, characterized in that the wetting layer (14) contains between about 30 to about 75 %w / w distilled and / or demineralized and / or deionized water and about 25 to about 70 %w / w dipropylene glycol.

3. The method according to claim 1 or 2, characterized in that the wetting layer (14) is sprayed onto the starting product (1).

4. The method according to claim 1 or 2, characterized in that the wetting layer (14) is applied to the starting product (1) by brushing.

5. The method according to claim 1 or 2, characterized in that the wetting layer (14) is applied to the starting product (1) by polishing.

6. The method according to one of claims 1 to 5, characterized in that the wetting layer (14) is applied to the starting product (1) over the entire surface.

7. The method according to one of claims 1 to 6, characterized in that the wetting layer (14) is applied to the starting product (1) on both sides.

8. The method according to one of claims 1 to 7, characterized in that the wetting layer (14) is applied to the starting product in the feed direction of the starting product (1) before a punching device (11).

9. The method according to one of claims 1 to 7, characterized in that the wetting layer (14) is applied to the starting product (1) by means of at least one application unit (15) provided on a punching tool.

10. The method according to one of claims 1 to 9, characterized in that an application unit (12) for the glue is provided on the punching tool.

11. The method according to one of claims 1 to 7, characterized in that the glue and the wetting layer (14) are applied to the lamella (2) immediately before or after the stamping out process.

12. The method according to one of claims 1 to 7, characterized in that, given a tape-shaped starting product (1), the wetting layer (14) is applied to the starting product (1) in the feed direction of the starting product (1) after the coating process and before winding on a reel (10).

13. A method according to one of claims 1 and 7, characterized in that, given a tape-shaped starting product (1), the wetting layer (14) is applied in the feed direction of the starting product (1) before splitting the tape.