Bonding of lamella packs using LIFT technology

Abstract

In a method for manufacturing a sheet metal lamella pack (4) for an electric machine, sheet metal lamellae (22) are produced from a sheet (12) in stamping steps (SSa-d), an adhesive (36) is applied to at least one flat side (40a,b) of the sheet metal lamellae (22) in printing steps (DSa,b) using print heads (30a-e) in a LIFT process, and in a stacking step (AS) the sheet metal lamellae (22) are stacked on top of each other to form the lamella pack (4) and are bonded together thanks to the adhesive (36). A manufacturing unit (2) for producing the sheet metal lamella package (4) includes a punching module (20a-d) for the punching steps (SSa-d), printing modules (28a,b) with printheads (30a,b) for the printing steps (DSa,b) and a stacking module (31) for the stacking step (AS).

Description

[0001] The invention relates to laminated lamination packs for electrical machines, e.g. packs for rotors or stators of electric motors.

[0002] From WO 2019 / 086634 A1, the following are known: a method for producing an electrical steel core using an anaerobically curing adhesive, an electrical steel core produced or producible by such a method, and a device for producing an electrical steel core. During the manufacturing process, the anaerobically curing adhesive is activated by rubbing the electrical steel strip with a rubbing device comprising a beryllium and / or transition metal-containing surface structure, preferably copper-containing surface structures. In a preferred embodiment, the rubbing device is a brush.

[0003] The object of the present invention is to improve the bonding of lamination packs.

[0004] The object of the invention is achieved by a method according to patent claim 1. Preferred or advantageous embodiments of the invention and other categories of invention emerge from the further claims, the following description and the attached figures.

[0005] The method is used or is designed to produce a laminated core stack for an electrical machine. Such a stack is also simply called a "laminated core stack." The laminated core stack contains a plurality or multiplicity of, in particular, comparatively thin, flat, and in particular identical, laminated cores or "laminates," each having two parallel flat sides. The cores are stacked on top of one another in alignment, flat side to flat side, and two adjacent cores are glued together on each flat side.

[0006] In the process, at least two sheet metal laminations are manufactured. In particular, a plurality of sheet metal laminations is produced. Each of the sheet metal laminations has two opposing flat sides. The sheet metal laminations are manufactured in such a way that each of the sheet metal laminations is produced from a sheet metal in at least one punching step. Typically, several punching steps are required to produce each sheet metal lamination. The punching steps are, in particular, part of a continuous punching process as part of a manufacturing process, which also includes, in particular, the bonding of the sheet metal laminations to one another and their packaging to form the sheet metal lamination package, as explained further below.

[0007] In this process, an adhesive is printed onto at least one, and in particular exactly one, flat side of each sheet metal lamella to be bonded in at least one printing step. Specifically, the first or last sheet metal lamella of a sheet metal lamella pack remains free of adhesive, since the adhesive is already applied to the bonding partner, namely the adjacent sheet metal lamella.

[0008] In this process, the adhesive is applied to the respective sheet metal lamella in each printing step by printing on it or its flat side using at least one printhead in a LIFT process (Laser Induced Forward Transfer), i.e., using LIFT technology. In this printing step, the sheet metal lamella may already be present as a separate sheet or still be part of the sheet metal, for example, a strip of sheet metal, from which the sheet metal lamella is ultimately produced or separated.

[0009] Several printheads can be combined in a single print module. Their relative spatial arrangement to each other is specifically defined within this module.

[0010] The LIFT technology is to be understood as follows: From “Laser-Induced Forward Transfer: A Method for Printing Functional Inks”, by J. Marcos Fernändez-Pradas and Pere Serra, Crystals 2020, 10(8), 651; Published: July 29, 2020, downloaded on April 25, 2023, from https: / / www.mdpi.com / 2073-4352 / 10 / 8 / 651, the following is known: Laser-induced forward transfer (LIFT) is a direct-printing process based on the action of a laser, which prints a small portion of a material from a thin donor layer onto a receiving substrate. Since the process's inception, solid donor layers or films have been used, but the same operating principle also works with liquid ink films. LIFT is a nozzle-free printing process that has virtually no restrictions on the particle size and viscosity of the ink to be printed.Therefore, LIFT is a versatile process that can be used to print any functional material for which an ink can be formulated.

[0011] In this case, the adhesive is applied to the flat side in a similar way to the material applied to a substrate using a LIFT print head. The adhesive is applied using a LIFT printing process, in which a print pattern, in this case an "adhesive pattern" or "adhesive application," is created by the targeted firing of adhesive from a supply of adhesive onto a donor layer. Such print heads belong to the group of non-impact print heads, meaning they do not make contact with the flat side during adhesive application. In other words, the adhesive is applied to the flat side "through the air."

[0012] The adhesive to be applied by the respective print head can also be an adhesive component of a multi-component adhesive (e.g., two-component adhesives, "2K adhesives") or a no-mix adhesive, or even its activator, etc. Suitable print heads are commercially available, for example, from Altana AG (A-belstraße 43, 46483 Wesel, Germany), https: / / www.altana.de / innovation / altanaplattformen / heliosonic.html. Any adhesive can be used, provided it can be applied by such print heads using the LIFT process.

[0013] The process also includes a stacking step, which follows the punching and printing steps, i.e., only takes place after their execution / completion. "After their execution / completion" is also to be understood in particular to mean that stacking generally occurs simultaneously with punching the final contour. The sheet metal laminations to be bonded, which are printed with adhesive on the flat side, are stacked on top of one another in the stacking step to form the lamination stack and are bonded together using the adhesive. If necessary, the sheet metal laminations are also pressed against one another during the stacking step to achieve a defined bond.

[0014] The adhesive application for bonding sheet metal laminations to form laminated cores for electric motors using LIFT technology allows for an extremely flexible dispensing pattern of the adhesive on the flat side and enables bonding over the largest possible area or even the entire surface, since the adhesive can be applied, for example, across the entire surface up to the edge of the lamination (see below). This is advantageous for the further development of the sheet metal composite, as the mechanical strength, in particular, can be very effectively demonstrated in an inline process. According to the invention, a particularly large-area bonding of sheet metal laminations to form laminated cores is achieved using LIFT technology.

[0015] In a preferred embodiment, the sheet metal is provided as a strip or strip material with both flat sides. This allows the invention to be integrated into conventional strip production of sheet metal lamella packs.

[0016] In a preferred embodiment, the punching, pressing, and stacking steps are performed as a continuous inline process on the strip material. The process continues on the strip material until the laminations are separated from it. The process then continues on the separated laminations, but even then, in the present sense, it still constitutes a continuous inline process "on the strip material." This allows for particularly efficient production of sheet metal stacks.

[0017] In a preferred embodiment, at least two punching steps are performed consecutively, and at least one printing step is performed between two of the punching steps. This allows the adhesive application to be integrated particularly favorably into the punching process.

[0018] However, for a single tooth, only a single punching step is also conceivable. The printing step is then performed before or after.

[0019] In a preferred embodiment, the adhesive is printed onto the entire flat surface of at least one, preferably all, of the sheet metal lamellae (except for those not to be printed). "Entire flat surface" is to be understood here in a technical sense. For example, a very small edge area of ​​the sheet metal lamella can be left uncovered compared to the surface area, so that the adhesive does not interfere with further processing steps of the sheet metal lamellae during the subsequent manufacturing of the sheet metal stack or ooze out laterally from the stack. An adhesive-free edge area allows, for example, tolerances in the amount of adhesive applied, viscosity, and manufacturing inaccuracies, etc., to be taken into account in a technical sense, while still achieving a technically complete bond of the sheet metal lamellae. Sheet metal lamellae bonded in this way contribute to a particularly stable and media-tight lamella stack.

[0020] Full-surface bonding is one option. However, partial and spot bonding is also possible as an alternative.

[0021] In a preferred embodiment, the method includes at least one additional (optional) surface activation step on at least one flat side of the lamellae or strip. This step is performed before the stacking step, particularly before the last, and especially before all printing steps. This step pre-activates the surface of at least one flat side of the lamella. Specifically, the surface activation step is performed on the flat side where the adhesive is to be applied, in order to prepare the surface favorably for adhesive application. The surface could also be activated in this way, for example, for another adhesive component, such as an activator for a no-mix adhesive.

[0022] In a preferred embodiment, the method includes at least one additional (optional) adhesive activation step. This step is performed after the first, and in particular all, printing steps, and in any case before the stacking step, and pre-activates the adhesive applied to the lamella. This pre-activation allows for particularly good bonding of the sheet metal lamellae to one another during the stacking step. Furthermore, it enables energy savings through lower required curing temperatures or even room-temperature curing. This step can be carried out, for example, using a flash device. IR / heat emitter / UV pre-activation is also conceivable.

[0023] In a preferred embodiment, at least one additional (optional) detection step is carried out in the process. This is carried out after the first printing step, in particular after all printing steps, and in any case before the stacking step. In the detection step, an actual print of the adhesive is detected. This makes it possible to evaluate how the adhesive was actually printed in the process. For example, the actual print can be compared with a target print and, if necessary, the production process can be readjusted if the adhesive is not printed according to the target specifications. This makes it possible to at least partially check that the adhesive has been successfully applied to the slats. A camera, for example, is a suitable detector.

[0024] In a preferred embodiment, the adhesive is printed onto at least one, and in particular all, of the sheet metal lamellae in at least, and in particular exactly two, successive printing steps. The adhesive is applied sequentially, in particular by means of at least, and in particular exactly two, different printheads. Initially, in a first partial printing step, only a portion of the adhesive is printed. Only later do further partial printing steps occur, in which the remaining adhesive is applied to the same lamella. Parts of the adhesive application thus occur at different times and / or from different printheads, in particular with an intervening pause. This allows, for example, an increased process speed to be achieved that would not be attainable with a single printhead / a single continuous print job alone, e.g.Because a single print head alone is not capable of printing at the required speed. The distribution depends on the press design and / or the geometry of the print heads.

[0025] In a preferred embodiment, the method is carried out using or in a manufacturing device (see below). This device has a stationary base frame – for example, in a production facility. At least one of the printheads remains stationary during at least one of the printing steps, i.e., during the printing process, in or on / relative to the base frame. In particular, the metal plate is moved relative to the printhead during printing. Alternatively, the metal plate can also remain stationary during printing. This allows for a particularly simple printhead design.

[0026] In a preferred embodiment, the method is also carried out with the aid of or in the aforementioned production system. At least one of the print heads moves relative to the base frame during at least one of the printing steps, i.e., the printing itself. The sheet metal lamination itself can also move during printing or remain stationary relative to the base frame. This allows for particularly flexible printing.

[0027] In a preferred embodiment, at least one of the printheads moves during at least one of the printing steps, i.e., during the printing process, in at least one, and in particular exactly one, direction of movement relative to the base frame that is not parallel to a transport direction of the sheet metal strip. Specifically, it moves in a direction transverse or perpendicular to the transport direction, and in a direction that runs parallel to the flat side of the sheet metal strip to be printed. This enables particularly efficient printing. The direction / path of movement of the printhead is, in particular, a straight line. This movement is, in particular, the only movement of the printhead relative to the base frame. Alternatively, a combination with other movements can be implemented.

[0028] In a preferred embodiment, at least one of the printheads moves by rotating around at least, and in particular exactly, one axis of rotation relative to the base frame during printing. The axis of rotation is, in particular, perpendicular to the transport direction of the slats, and especially perpendicular to a plane of extension of the flat side of the slats or the sheet / strip to be printed. This also allows for particularly effective printing of the slats. The printhead can, for example, perform one rotation per printing operation or continue to rotate continuously – even during non-printing periods. In the latter case, acceleration during the printing process is then unnecessary.

[0029] The object of the invention is also achieved by a manufacturing device according to claim 14. This device serves, or is configured, for manufacturing the aforementioned sheet metal lamella stack for the electric machine according to the aforementioned method. The manufacturing device contains at least one punching module. The punching modules are configured as a whole to perform the punching steps described above. The manufacturing device contains at least one printing module. Each of the printing modules contains at least one of the aforementioned printheads. The printing modules are configured as a whole to perform the aforementioned printing steps. The manufacturing device contains a stacking module. This module is configured to perform the aforementioned stacking step, in particular the bonding / curing.

[0030] The manufacturing facility and at least some of its possible embodiments as well as the respective advantages have already been explained in connection with the method according to the invention.

[0031] Optionally, the production facility also includes a curing module, e.g., for heat curing; possibly under pressure, if necessary.

[0032] In preferred embodiments, the manufacturing facility contains, alternatively or additionally: - at least one surface activator module, which is designed to carry out the above-mentioned surface activation steps in its entirety, - at least one adhesive activator module, which is designed to carry out the above-mentioned adhesive activation steps in their entirety, - at least one detector module, which is designed to carry out the above-mentioned detector steps in their entirety, - the basic framework mentioned above, - at least one transport module for the slats to transport them relative to the base frame.

[0033] In particular, the print head is in a fixed position relative to the base frame. In particular, the print head is movable relative to the base frame at least translationally in the at least one direction of movement. In particular, the print head is rotatable relative to the base frame about the at least one axis of rotation.

[0034] The processes are suitable for the production of full cut, segmented sheet stacks or even individual teeth.

[0035] The invention is based on the following findings, observations, and considerations and further comprises the following preferred embodiments. These embodiments are sometimes referred to simply as "the invention." The embodiments may also include parts or combinations of the embodiments mentioned above, correspond to them, and / or may include previously unmentioned embodiments.

[0036] The invention is based on the finding that three sheet metal joining technologies for electrical steel sheets are known in practice: In a first variant, insulation-coated sheets are punched and joined into a sheet metal stack using punching and / or welding. In a second variant, full-surface bonding (bake-on varnish) is used. Sheets pre-coated with bake-on varnish are punched and baked together under pressure and temperature to form a sheet metal stack. In a third variant, local bonding (liquid adhesive) is used. Insulation-coated sheets are punched, individual dots of adhesive are applied to the punched sheets, and these sheets are then joined into a complete sheet metal stack by stacking them under pressure and temperature or using a no-mix process at room temperature.

[0037] The invention is based on the recognition of the following problems: In variant two, adjacent lamellae are bonded together almost across their entire surface, resulting in advantages in terms of mechanical stiffness, bond strength, and media tightness between the sheet metal lamellae. Variant two has the disadvantage that the bonding is carried out in a separate process step downstream of the stamping step. This is comparatively complex and expensive (process time, equipment investment, energy consumption). Variant three is typically integrated into the stamping process and offers a joining technology that can be integrated into the cycle time of part production. Curing takes place at room temperature (contact polymerization in a no-mix process) or by brief heating in the stamping tool. The activator or adhesive is generally applied by spraying or contact application (stamp-like). Advantages include: time savings, shorter cycle times, and cost savings.Disadvantages include: lower bond strength compared to full-surface gluing; separate tools are needed for each new print layout.

[0038] In practice, it is also known that for a 2K (two-component) adhesive (curing at room temperature), an activator is applied to one flat side of a sheet metal strip using a spray coating process. The adhesive is then applied to the other flat side via a stamping process. This requires two separate steps. Punching and stacking, on the other hand, are performed in a single step.

[0039] In practice, it is also known for a 2K high-temperature adhesive (increased permanent temperature resistance at 180°C, even higher temperatures can be tolerated for short periods) or a 2K (two-component) adhesive (curing at room temperature) to apply an activator in a dot pattern via defined nozzles to one flat side of a sheet metal strip. The adhesive is then applied in a dot pattern via defined nozzles to the other flat side. This occurs in a simultaneous process (synchronous with the punching cycle). Punching and stacking, in turn, take place in a single step.

[0040] The invention is based on the idea of ​​achieving an improvement of variant three: By incorporating LIFT printing technology, the advantages of both variants two and three can be combined: • Full-surface (or at least large-scale) application of the liquid adhesive, whereby partial or local (point-by-point) application is also possible, • Prevention of electromagnetic short circuits between the lamellae • Almost any print layout - thus independent of the print layout can be implemented with one tool, the layout can be easily changed by (any) control of the laser control - as with laser / matrix printing, • extremely precise dosing technology (sharpness, application quantity), • High mechanical strength and stiffness in the sheet metal stack (lamella stack, similar to baked enamel technology), • Variable mechanics of the adhesive joint (adhesive layer between two lamellae) through targeted adhesive selection or modification, since LIFT technology allows for variable adhesives, • Media tightness is theoretically achievable, resulting in an interlaminar (i.e., tightness between adjacent lamellae) sealing function in the radial direction. • Avoidance of local increases in the sheet metal stack at point-contact bonding points • Integration in the punching process or offline possible, • Joining during the stamping cycle (approx. 150 strokes per minute) is possible, as no baking step is required, resulting in cost savings and energy efficiency. Depending on the adhesive, a baking step may not be necessary; only temperature control in the stacking device may be required. Compared to a baking lacquer, lower curing temperatures and / or curing times may suffice. • Variable print orientation (printing on the top or bottom of the ribbon is possible). With activator, NoMix, or 2K adhesive, printing is possible on both the top and bottom sides. • Influence of the acoustics by the print image and / or adhesive system

[0041] Furthermore, it is a contactless dosing process that minimizes material carryover during the process. This also ensures that any stamping waste is sorted by type and can be recycled more effectively.

[0042] Regardless, surface pre-activation (surface activation step, e.g. atmospheric pressure plasma, corona discharge, etc.) is possible as an optional process step in this process sequence.

[0043] Regardless of this, the pre-activation of a suitable adhesive (adhesive activation step) and / or optical detection of the adhesive image (detector step) is possible in this process sequence.

[0044] The following LIFT printhead configurations are possible: The dimensions of individual printheads are generally defined by the printhead manufacturer. Wider print areas can be accommodated by using multiple printheads, for example, in a staggered arrangement, such as for full-cut dies, but also for segmented sheet metal cuts or T-segments. Due to limited installation space, a custom-designed printhead with a suitable width would be preferable, but is not strictly necessary. The configuration can be implemented within one or more empty stages of the die-cutting process. Adhesive dispensing can be performed on the top or bottom of the sheet metal (overhead).

[0045] Further features, effects, and advantages of the invention will become apparent from the following description of a preferred embodiment of the invention and the accompanying figures. Each of these figures shows a schematic diagram: Fig. 1 a production facility for producing a sheet metal lamination package, Fig. 2 the punching and printing of an exemplary rotor sheet in the production facility Fig. 1, Fig. 3 the corresponding production of a rotor sheet made of Fig. 2 matching stator sheets, Fig. 4 the production of a stator lamination according to Fig. 3 with two printing modules, Fig. 5 the production of a stator lamination according to Fig. 3 with translationally movable pressure module, Fig. 6 the production of a stator lamination according to Fig. 3 with rotatable printing module.

[0046] Fig. 1 shows a production facility 2. This facility is used to manufacture a laminated core stack 4 for an electrical machine (not shown), in this case a rotor core and a stator core for an electric motor. The production facility 2 includes a base frame 6 mounted in a stationary manner in a production hall (not shown in further detail), as well as a punching tool 8, which is movable in the direction of the double arrow 10 to perform punching work in conjunction with the base frame 6.

[0047] The plate pack 4 is manufactured from a sheet metal 12, which is provided here as a (in the technical sense endless) strip 14 and is unrolled from a roll 16 and transported in a transport direction 18 (indicated by an arrow) through the production device 2.

[0048] The production device 2 contains (here only as an example) four punching modules 20a-d, which in four punching steps SSa-d successively produce a sheet metal lamination 22 (in Fig. (1 only indicated) are punched from the sheet metal 12 or strip 14 and separated in the punching step SSd. The sheet metal lamellae 22 are successively stacked on top of each other in a collection container 24 by a stacking module 31 and bonded together with adhesive 36, as will be explained further below.

[0049] The production device 2 contains a surface activator module 26, two printing modules 28a,b with (here only as an example) five print heads 30a-e each (see Fig. 2-6), an adhesive activator module 32, a detector module 33 and a curing station 34, in which the stacked or bonded lamella package 4 is cured with respect to its adhesive 36 (in Fig. (1 only symbolically indicated). The number of printheads depends on their geometry, the geometry of the stator or rotor lamination stack, and whether the stamping process is single-row or multi-row. An unspecified transport module 38 of the production unit 2 serves to transport the strip 14, the individual sheet metal lamellae 22, and the lamella stack 4 through the production unit 2.

[0050] In the production facility 2, the following process is now carried out to produce the disk pack 4 for the electrical machine: The sheet metal 12 is provided as strip material in the form of the strip 14 with the two flat sides 40a,b. A plurality of sheet metal laminations 22, each having two flat sides 40a,b corresponding to the flat sides 40a,b of the strip 14, are manufactured by producing each of the sheet metal laminations 22 from the sheet metal 12 in the four punching steps SSa-d (here only as an example) - each in the punching modules 20a-d. The number of punching steps depends on the stator / rotor design and / or the press properties. In two printing steps DSa,b - each in the printing modules 28a,b - adhesive 36 is applied to the sheet metal 12 or the laminations 22 using the printing heads 30a-e. In printing steps DSa,b in printing modules 28a,b, the adhesive 36 is printed by means of five printheads 30a-e each. The application is made to the lower flat side 40b or flat side 40a of each sheet metal lamella 22 to be bonded, as shown in the figure.The application is carried out by printing on a respective sheet metal lamination 22 using the print heads 30a-e in a LIFT process or using LIFT technology. In a stacking step AS, the sheet metal laminations 22 separated from the strip 14 are stacked on top of one another to form the sheet metal stack or lamination stack 4. This takes place in the collection container 24. Bonding takes place using the adhesive 36. This also involves a pressing of the individual sheet metal laminations 22 against one another in the direction of the double arrow 10 (not explained in detail).

[0051] The punching steps SSa-d, the printing steps DSa,b, and the stacking step AS are carried out as a continuous inline process using the strip material or strip 14 as the starting material. The four punching steps SSa-d are carried out sequentially in the four punching modules 20a-d. The printing steps DSa,b are carried out between the punching steps SSc,d in the punching modules 20c,d. The adhesive 36 is printed onto the entire flat side 40a and / or 40b of the respective sheet metal lamination 22. The application depends on the lamination geometry (recesses / openings / grooves are not supplied with adhesive 36, otherwise the system could become contaminated and adhesive consumption would increase).

[0052] In a surface activation step OS (plasma, corona, activators, brushes (copper ions)), a surface pre-activation of the flat side 40b and / or 40a of the sheet metal laminations 22, which will not be coated with adhesive 36 later, is carried out in the surface activator module 26 before the first punching step SSa and thus before all subsequent steps. Thus, the respective flat side 40b of the sheet metal laminations 22 should form a particularly good adhesive bond with the adhesive 36 on the flat side 40a of an adjacent sheet metal lamination 22.

[0053] In the adhesive activator module 32, an adhesive activation step KS is carried out after the printing steps DSa,b and before the stacking step AS in the stacking module 31.

[0054] In the adhesive activation step KS, the adhesive 36 is pre-activated so that it can optimally develop its adhesive effect when the sheet metal lamellae 22 are stacked to form the lamella package 4 in the stacking step AS, or so that the curing process is started.

[0055] In the detector module 33, after the printing steps DSa,b, an actual print of the adhesive 36 on the sheet metal lamella 22 is also detected in a detector step ES in order to check the correct printing.

[0056] Fig. 2 shows the production of rotor laminations 22. Fig. 2 shows a plan view in the direction of arrow II from Fig. 1 to the production facility 2, omitting the basic frame 6. The punching steps SSc,d in the punching modules 20c,d are shown. In a modification of Fig. However, in this case, there is only a single print module 28a with printheads 30a-e. The print module 28a rests on the base frame 6 or die-cutting tool 8. The application of the adhesive 36 to the flat side 40b (or 40a) occurs in each cycle step 42a-c, which corresponds to advancing the tape 14 by one unit of length (LE). The die-cutting steps SSa-d in the die-cutting module 20a-d, on the other hand, occur during the respective standstill of the tape 14 between two cycle steps 42a-c. Such a standstill lasts, for example, 0.2 seconds in a continuous process. In this example, printing does not occur during the standstill, but rather during the advance of the tape 14. However, the 0.2 s can also be assumed for the advance as an example. This is the amount of time then available for printing.

[0057] Fig. Figure 3 shows the production of stator sheet metal lamellae 22 (larger than the rotor). To achieve optimal coverage of the strip 14 across its entire width (sufficient even for rotor sheet metal) and to enable the entire strip area / width to be printed with adhesive 36, a total of five printheads 30a-e are arranged in two offset rows within the print module 28a (print module 28b is identical in this respect, see below). In reality, this depends on the stator / rotor geometry and whether the printing process involves two or more rows. Fig. 2 and Fig. Therefore, not only a rotor but also a stator sheet metal lamella 22 can be fully coated with adhesive 36 using the same pressure module 28a.

[0058] The Fig. 2 and Fig. 3 therefore show a sequence of application steps in the punching sequence. A first case is shown here: the application takes place in the feed step (cycle step 42a) of the punching process (sheet metal 12 in motion). The sheet metal 12 is therefore in motion (dynamic process step), and the print heads 30a-e / the print module 28a are rigidly mounted on the base frame 6. Area 48 therefore shows a LIFT printing station in an idle stage of the punching process (application stage). The punching module 20d forms an "outer contour punching stage" (adhesive 36 is dispensed).

[0059] The stator surface (stator lamination 22) may need to be printed with adhesive in two steps: Fig. 4 shows in accordance with Fig. 1. Therefore, both printing modules 28a and 28b are arranged at intervals from each other in the transport direction 18 of the belt 14 and the sheet metal lamellae 22, respectively. In a first cycle step 42a, the printing module 28a coats the first half of the sheet metal lamella 22 with adhesive 36, while the second half remains adhesive-free. Only in cycle step 42b is the remaining second half of the sheet metal lamella 22 coated with adhesive 36. The two halves are indicated again by dashed lines, where an actual, seamless application of adhesive 36 takes place.

[0060] Fig. Figure 4 therefore shows a process variant for better surface coverage of the sheet metal cut during adhesive dosing (especially in the stator).

[0061] Fig. Figure 5 shows an exemplary sequence of application steps in the stamping sequence, here a second case: dosing in the stamping step of the stamping process.

[0062] Fig. Figure 5 shows an alternative pressure module 28a in the manufacturing device 2, which is not fixedly arranged on the base frame 6 or the stamping tool 8 like the pressure modules 28a,b of the Fig. 2 to 4. Here, the printing module 28a is translationally displaceable in a direction of movement 44 (indicated by double arrows) relative to the base frame 6 or the die-cutting tool 8. The direction of movement 44 runs parallel to the flat sides 40a,b and perpendicular to the transport direction 18. Furthermore, unlike the Fig. 2 to 4 not during the cycle steps 42a-c, but in cycle breaks between respective cycle steps 42a-c, i.e., when the strip 14 is at rest relative to the base frame 6 or the punching tool 8. Printing is performed by moving the printing module 28a in each direction of the double arrow of the movement direction 44. After the next cycle step 42a-c, the printing module 28a is moved back in the opposite direction and prints the next sheet metal lamination 22 with adhesive 36. Fig. 5 therefore shows, for example, the starting position of the print heads 30a-e (print module 28a) before dispensing at the top of the image, and the final position of the print heads 30a-e after dispensing at the bottom. Here, too, the adhesive application takes place in an idle stage (no punching activity here) of the punching process.

[0063] According to Fig. In step 5, the sheet 12 is stationary (static process step), and the print heads 30a-e are in motion. Their alternating movement occurs transversely to the transport direction 18. A similar process is used for the rotor.

[0064] Fig. Figure 6 shows an exemplary sequence of application steps in the punching sequence, here a case 3: Dosing in the punching step of the punching process.

[0065] Fig. 6 shows a further alternative embodiment of a printing module 28a. Here, it is also mounted movably with respect to the base frame 6, but here it rotates about a rotation axis 46 for printing, as in Fig. 6 is indicated by arrows. Here, too, the printing of the sheet metal lamella 22 with adhesive 36 takes place between two cycle steps 42a-c, i.e., with the strip 14 or sheet metal lamella 22 at rest relative to the base frame 6.

[0066] Here too, sheet 12 remains stationary (static process step). The printheads 30a-e are in motion. The printhead assembly / print module 28a rotates. An analogous procedure is applied to the rotor.

[0067] Reference symbol 2 Manufacturing facility 4 slat package 6 Basic framework 8 Punching tool 10 Double Arrow 12 sheets 14 volumes 16 rolls 18 Transport direction 20a-d punching module 22 sheet metal slats 24 collection containers 26 Surface activator module 28a,b Print module 30a-e printhead 31 Stacking module 32 Adhesive activator module 33 Detector module 34 Curing station 36 Adhesive 38 Transport module 40a,b Flat side 42a-c bar step 44 Direction of movement 46 axis of rotation 48 Area LE unit of length SSa-d punching step DSa,b pressure step AS stacking step OS surface activation step KS adhesive activation step ES detector step QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] WO 2019 / 086634 A1

[0002] Cited non-patent literature

[0000] Laser-Induced Forward Transfer: A Method for Printing Functional Inks", by J. Marcos Fernandez-Pradas and Pere Serra, Crystals 2020, 10(8), 651

[0010] Published: July 29, 2020, downloaded on April 25, 2023 from https: / / www.mdpi.com / 2073-4352 / 10 / 8 / 651

[0010] Altana AG (Abelstrasse 43, 46483 Wesel, Germany), https: / / www.altana.de / innovation / altanaplattformen / heliosonic.html

[0012]

Claims

[1] Method for producing a laminated core (4) for an electrical machine, in which: - at least two sheet metal lamellae (22) each having two flat sides (40a,b) are produced by manufacturing each of the sheet metal lamellae (22) from a sheet metal (12) in at least one punching step (SSa-d), - in at least one printing step (DSa,b) an adhesive (36) is printed onto at least one flat side (40a,b) of each sheet metal lamella (22) to be bonded, - wherein the adhesive (36) is applied to the respective sheet metal lamella (22) by printing on the respective sheet metal lamella (22) with the aid of at least one print head (30a-e) in a LIFT process, - in a stacking step (AS) following the punching steps (SSa-d) and the printing steps (DSa,b), the sheet metal laminations (22) are stacked on top of one another to form the lamination pack (4) and are glued to one another by means of the adhesive (36). [2] Method according to claim 1,characterized by that the sheet (12) is provided as a strip (14) with the two flat sides (40a,b). [3] Method according to claim 2, characterized by that the punching steps (SSa-d), the printing steps (DSa,b) and the stacking step (AS) are carried out as a continuous inline process on the strip (14) as starting material. [4] Method according to one of the preceding claims, characterized by that at least two punching steps (SSa-d) are carried out one after the other and at least one of the printing steps (DSa,b) is carried out between two of the punching steps (SSa-d). [5] Method according to one of the preceding claims, characterized by that the adhesive (36) is printed onto the entire respective flat side (40a,b) of at least one of the sheet metal lamellas (22). [6] Method according to one of the preceding claims, characterized bythat in at least one surface activation step (OS) before the stacking step (AS) a surface pre-activation of at least one flat side (40a,b) of the sheet (12) is carried out. [7] Method according to one of the preceding claims, characterized by that in at least one adhesive activation step (KS) after the printing steps (DSa,b) and before the stacking step (AS) a pre-activation of the adhesive (36) is carried out. [8] Method according to one of the preceding claims, characterized by that in at least one detector step (ES) after the printing steps (DSa,b) and before the stacking step (AS) an actual print of the adhesive (36) is detected. [9] Method according to one of the preceding claims, characterized by that the adhesive (36) is printed onto at least one of the sheet metal lamellae (22) in at least two successive printing steps (DSa,b). [10] Method according to one of the preceding claims, characterized by , that - the method is carried out with the aid of or in a production facility (2) with a stationary base frame (6), and - at least one of the print heads (30a-e) rests relative to the base frame (6) during at least one of the printing steps (DSa-b). [11] Method according to one of the preceding claims, characterized by , that - the method is carried out with the aid of or in a production facility (2) with a stationary base frame (6), and - at least one of the print heads (30a-e) moves relative to the base frame (6) during at least one of the printing steps (DSa-b). [12] Method according to claim 11, characterized by that at least one of the print heads (30a-e) moves by moving relative to the base frame (6) in a direction of movement (44) that is not parallel to a transport direction (18) of the sheet metal lamella (22). [13] Method according to one of claims 11 to 12, characterized by that at least one of the print heads (30a-e) moves by rotating relative to the base frame (6) about an axis of rotation (46). [14] Manufacturing device (2) for producing a laminated core (4) for an electrical machine according to a method according to one of the preceding claims, - with at least one punching module (20a-d) which is designed to carry out the punching steps (SSa-d), - with at least one printing module (28a,b), wherein each of the printing modules (28a,b) contains at least one of the print heads (30a,b), wherein the printing modules (28a,b) are adapted to carry out the printing steps (DSa,b), - with a stacking module (31) which is designed to carry out the stacking step (AS).

Images