Adhesively bonding laminated cores using inkjet technology

Abstract

The invention relates to a method for manufacturing a laminated core (4) for an electric machine, in which: in punching steps (SSa-d), laminations (22) are produced from a metal sheet (12); in printing steps (DSa, b), an adhesive (36) is applied to at least one flat side (40a, b) of the laminations (22) by means of print heads (30a-e) in an inkjet method; and in a stacking step (AS), the laminations (22) are stacked on top of one another to form the laminated core (4) and are adhesively bonded together by means of the adhesive (36). A production device (2) for manufacturing the laminated core (4) contains punching modules (20a-d) for the punching steps (SSa-d), printing modules (28a, b) comprising print heads (30a, b) for the printing steps (DSa, b), and a stacking module (31) for the stacking step (AS).

Description

[0001] Bonding of lamella packs with inkjet technology

[0002] The invention relates to laminated lamination packs for electrical machines, e.g. packs for rotors or stators of electric motors.

[0003] WO 2019 / 086634 A1 discloses a method for producing an electrical steel sheet stack using an anaerobic-curing adhesive, an electrical steel sheet stack produced or producible by such a method, and a device for producing an electrical steel sheet stack. During the production process, the anaerobic-curing adhesive is activated by rubbing the electrical steel strip with a rubbing device comprising a surface structure containing beryllium and / or transition metals, preferably copper-containing surface structures. In a preferred embodiment, the rubbing device is a brush.

[0004] The object of the present invention is to improve the bonding of lamination packs.

[0005] The object of the invention is achieved by a method according to claim 1. Preferred or advantageous embodiments of the invention as well as other categories of invention emerge from the further claims, the following description and the attached figures.

[0006] The method is used or is designed to produce a laminated lamination stack for an electrical machine. Such a stack is also simply called a "lamination stack." The lamination stack contains a plurality or multiplicity of, in particular, comparatively thin, flat, and in particular identical, laminated laminations or "laminations," each having two parallel flat sides. The laminations are stacked on top of one another in alignment, flat side to flat side, and two adjacent laminations are glued together on each flat side. In the method, at least two laminated laminations are produced. In particular, a plurality of laminated laminations is manufactured. Each of the laminated laminations has two opposite flat sides. The laminated laminations are manufactured in such a way that each of the laminated laminations is produced from a sheet metal in at least one stamping step. Typically, several stamping steps are required to produce each laminated lamination.The punching steps are in particular part of a continuous punching process as part of a manufacturing process, which in particular also includes 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 the process, an adhesive is also printed in at least one printing step onto at least one, in particular exactly one, flat side of each sheet metal lamination to be bonded. In particular, the first or last sheet metal lamination of a sheet metal lamination stack remains adhesive-free, since the adhesive is already applied to the bonding partner, namely the adjacent sheet metal lamination.

[0008] In the process, the adhesive is applied to the respective sheet metal lamella or its flat side in the respective printing step by printing it using at least one print head in an inkjet process, i.e., using inkjet technology. In the printing step, the sheet metal lamella may already be present in a separate form or may still be part of the sheet metal, for example, a sheet metal strip, from which the sheet metal lamella is ultimately manufactured or separated.

[0009] Several print heads can be combined in a print module, which specifically defines their relative spatial arrangement.

[0010] Inkjet technology is understood as follows: Adhesive is applied to the flat surface, similar to the application of ink to a printing substrate, using an inkjet printer (also called droplet-jet printer, inkjet printer, color jet printer, and ink-jet printer). The adhesive is thus applied using a matrix printing process, in which a print image, in this case an "adhesive image" / "adhesive application," is created by the targeted firing of small ink nozzles, in this case adhesive nozzles, or the deflection of small ink droplets (adhesive droplets). Such printers, in this case print heads, belong to the group of non-impact printers / print heads, which therefore do not make contact with the flat surface during the adhesive application. In other words, the adhesive is applied to the flat surface "through the air." For such print heads, see the explanations for inkjet printers, e.g., according to https: / / de.wikipedia.org / wiki / Tintstrahldrucker.

[0011] The adhesive applied by the respective printhead 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 printheads are commercially available, for example, from Xaar (Xaar plc Headquarters, 3950 Cambridge Research Park, Waterbeach, Cambridge, CB25 9PE, United Kingdom), https: / / www.xaar.com / de / produkte / xaar-druckköpfe. Any adhesive can be used, provided it can be applied by such printheads using the inkjet process.

[0012] 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 of 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.

[0013] The application of the adhesive for bonding sheet metal laminations to laminated cores for electric motors using inkjet technology allows extremely flexible dosing of the adhesive on the flat side and enables bonding over the largest possible area or even over the entire surface, since the adhesive can be applied, for example, right up to the edge of the lamination, see below. This is advantageous for the further development of the sheet metal composite, since the mechanical strength in particular can be very well demonstrated in an inline process. According to the invention, a particularly large-area bonding of sheet metal laminations to laminated cores is achieved using inkjet technology. In a preferred embodiment, the sheet metal is provided as a strip or strip material with the two flat sides. The invention can thus be integrated into conventional strip production of sheet metal lamination cores.

[0014] In a preferred variant of this embodiment, the punching steps, the printing steps, and the stacking step are carried out as a continuous inline process using the strip / material as the starting material. The process continues on the strip material until the laminations are separated from the strip material. The process then continues on the separated laminations, but in the present sense, it still represents a continuous inline process "on the strip material." This allows for particularly efficient production of laminated cores.

[0015] 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.

[0016] However, for a single tooth, only a single punching step is also conceivable. The printing step is then performed before or after.

[0017] In a preferred embodiment, the adhesive is printed onto the entire flat side of at least one, preferably all, of the laminations (except for those not to be printed). "Entire flat side" is to be understood here in the technical sense. For example, a very small edge area of ​​the lamination, compared to the surface area, can be left free so that the adhesive does not interfere with further processing steps of the laminations during the subsequent production of the lamination stack or ooze out of the sides of the lamination stack. By leaving the edge area free of adhesive, tolerances in the amount of adhesive applied, viscosity, manufacturing inaccuracies, etc., can be taken into account in a technical sense, while still achieving a full-surface bonding of the laminations in the technical sense. Correspondingly bonded laminations contribute to a particularly stable and media-tight lamination stack. Full-surface bonding is an option.However, partial and selective bonding is also possible as an alternative.

[0018] 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 is performed before the stacking step, in particular before the last step, in particular before all printing steps. This step effects a surface pre-activation of at least one flat side of the lamella. In particular, the surface activation step is performed on or at the flat side to which the adhesive is to be applied in order to favorably prepare the surface for the application of the adhesive. The surface could also be activated in this way, for example, for another adhesive component, such as an activator for a NoMix adhesive.

[0019] In a preferred embodiment, at least one additional (optional) adhesive activation step is performed 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, and results in pre-activation of the adhesive applied to the lamella. This pre-activation allows for particularly good bonding of the sheet metal lamellas during the stacking step. Furthermore, this enables energy savings due to the lower required curing temperature or even room-temperature curing. This step can be performed, for example, using a flash device. IR / heat lamp / UV pre-activation is also conceivable.

[0020] 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 lamellas. A camera, for example, is a suitable detector.

[0021] In a preferred embodiment, the adhesive is printed onto at least one, in particular all of the respective metal laminations in at least, in particular exactly two consecutive printing steps. The adhesive is printed sequentially, in particular by means of at least, in particular exactly two different print heads. Initially, only a portion of the adhesive is printed in a first partial printing step. Only later do further partial printing steps follow, in which the remaining adhesive is applied to the same lamination. Parts of the adhesive application therefore take place at different times and / or from different print heads, in particular with an intermediate time pause. This makes it possible, for example, to achieve an increased process speed that would not be achievable with one print head / single continuous print 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.

[0022] In a preferred embodiment, the method is carried out with the aid of or in a manufacturing facility (see below). This facility has a stationary base frame—e.g., in a production facility. At least one of the print heads is stationary during at least one of the printing steps, i.e., printing in or on / relative to the base frame. In particular, the metal lamination is moved relative to the print head during printing, i.e., during printing. Alternatively, the metal lamination can also remain stationary during printing. This allows for a particularly simple print head structure.

[0023] 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.

[0024] In a preferred variant of this embodiment, at least one of the print heads moves during at least one of the printing steps, i.e., printing, in at least one direction of movement relative to the base frame, in particular exactly one direction that is not parallel to a transport direction of the sheet metal lamination. In particular, it moves in a direction of movement that is transverse or perpendicular to the transport direction. In particular, it moves in a direction of movement that runs parallel to the flat side of the sheet metal lamination to be printed. This enables particularly effective printing. The direction / path of movement of the print head is in particular a straight line. In particular, this movement is the only one of the print head relative to the base frame. Alternatively, a combination with other movements can be carried out.

[0025] In a preferred variant of this embodiment, at least one of the print heads moves by rotating about at least, 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, in particular perpendicular to a plane of extension of the flat side of the slats or sheet / strip to be printed. This also allows particularly effective printing of the slats. The print head can, for example, perform one rotation / turn per printing process or continue to rotate continuously - even during non-printing times. In the latter case, there is no need for any acceleration during the printing process.

[0026] The object of the invention is also achieved by a manufacturing device according to patent claim 14. This serves or is configured to produce the above-mentioned laminated lamination stack for the electrical machine according to the above-mentioned method. The manufacturing device contains at least one punching module. The punching modules as a whole are configured to carry out the punching steps explained above. The manufacturing device contains at least one printing module. Each of the printing modules contains at least one of the above-mentioned print heads. The printing modules as a whole are configured to carry out the above-mentioned printing steps. The manufacturing device contains a stacking module. This is configured to carry out the above-mentioned stacking step, in particular also the bonding / curing.

[0027] 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.

[0028] Optionally, the production facility also includes a curing module, e.g., for heat curing; possibly under pressure, if necessary.

[0029] In preferred embodiments, the manufacturing facility contains, alternatively or additionally:

[0030] - at least one surface activator module, which is designed to carry out the above-mentioned surface activation steps in its entirety,

[0031] - at least one adhesive activator module, which is designed to carry out the above-mentioned adhesive activation steps in their entirety,

[0032] - at least one detector module, which is designed to carry out the above-mentioned detector steps in their entirety,

[0033] - the basic framework mentioned above,

[0034] - at least one transport module for the slats to transport them relative to the base frame.

[0035] 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.

[0036] The methods are suitable for producing full-cut, segmented lamination stacks, or even individual teeth. The invention is based on the following findings, observations, and considerations and also features the following preferred embodiments. These embodiments are sometimes referred to as "the invention" for simplification. The embodiments may also contain parts or combinations of the above-mentioned embodiments or correspond to them and / or may also include previously unmentioned embodiments.

[0037] The invention is based on the realization that three sheet metal joining technologies for E-sheets are known in practice: In a first variant, insulation-coated sheets are punched and joined to form a sheet stack using punching and / or welding. In a second variant, full-surface bonding (baking varnish) takes place. Sheets pre-coated with baking varnish are punched and baked together under pressure and temperature to form a sheet stack. In a third variant, local bonding (liquid adhesive) takes place. Insulation-coated sheets are punched, individual adhesive dots (dotted glue) are applied to the punched sheets, and these sheets are joined to form a complete sheet stack by stacking them using pressure and temperature or using the no-mix process at room temperature.

[0038] The invention is based on the recognition of the following problems: In variant two, adjacent laminations are bonded together almost over their entire surface, which results in advantages in terms of mechanical rigidity, bond strength, and media impermeability between the sheet metal laminations. Variant two has the disadvantage that the bonding takes place in a separate process step following the punching step. This is comparatively complex and expensive (process time, equipment investment, energy consumption). Variant three is usually integrated into the punching process and offers a joining technology that can be integrated into the part production cycle. Curing takes place at room temperature (contact polymerization using the no-mix process) or by brief heating in the punching tool. The activator or adhesive is usually applied by spraying or using a contact process (stamp-like). Advantages are: time savings, shorter cycle times, and cost savings.Disadvantages include: lower bond strength compared to full-surface bonding; separate tools required for each new print layout.

[0039] In practice, it is also known for a 2K (two-component) adhesive (curing at room temperature) to apply an activator to one flat side of a sheet metal strip using a spray coating process. The adhesive is then applied to the other flat side using a stamping process. Two separate steps are required. Punching and stacking, in turn, are carried out in a single step.

[0040] 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.

[0041] The invention is based on the idea of ​​improving variant three: By incorporating inkjet printing technology, the advantages of both variants two and three can be combined:

[0042] • Full-surface (or at least large-scale) application of the liquid adhesive, whereby partial or local (point-by-point) application is also possible,

[0043] • Avoiding electromagnetic short circuits between the slats

[0044] • 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 individual nozzles / matrix nozzles - as with matrix printing,

[0045] • extremely precise dosing technology (sharpness, application quantity),

[0046] • high mechanical strength and rigidity in the laminated core (laminated core, similar to self-adhesive technology), • variable mechanics of the adhesive joint (adhesive layer between two laminations) through targeted adhesive selection or modification, since inkjet technology allows for variable adhesives,

[0047] • Media tightness theoretically feasible, resulting in an interlaminar (i.e. tightness between adjacent lamellas) sealing function in the radial direction

[0048] • Avoidance of local elevations of the sheet stack at specific bonding points

[0049] • Integration in the punching process or offline possible,

[0050] • Joining in the punching cycle (approx. 150 strokes per minute), as no baking step is required, resulting in cost savings and energy efficiency. Depending on the adhesive, no baking step may be required, but only temperature control in the stacking device. Compared to self-bonding varnish, lower curing temperatures and / or curing times may be sufficient.

[0051] • 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.

[0052] • Influence of the acoustics by the print image and / or adhesive system

[0053] In addition, it's a contactless dispensing process that minimizes material carryover during the process. This also ensures that any punching waste is sorted and can be more easily recycled.

[0054] Independently of this, 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.

[0055] 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. The following possible arrangements of the inkjet print heads are available: The dimensions of individual print heads are generally defined by the print head manufacturer. Adaptation for wider printing areas is achieved by using multiple print heads, e.g. in a staggered arrangement, e.g. for full cuts but also for segmented sheet metal cuts or T-segments. Due to the limited installation space, a custom-made print head with a suitable width would be preferred but not absolutely necessary. The arrangement can be carried out within one or more empty steps of the punching process. The adhesive can be dispensed on the top or bottom of the sheet (overhead).

[0056] 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:

[0057] Figure 1 shows a production facility for producing a sheet metal lamination package,

[0058] Figure 2 shows the punching and printing of an exemplary rotor sheet in the production facility from Figure 1,

[0059] Figure 3 shows the corresponding production of a stator lamination matching the rotor lamination from Figure 2,

[0060] Figure 4 shows the production of a stator sheet according to Figure 3 with two printing modules,

[0061] Figure 5 shows the production of a stator sheet according to Figure 3 with a translationally movable pressure module,

[0062] Figure 6 shows the production of a stator sheet according to Figure 3 with a rotatable printing module.

[0063] Figure 1 shows a production facility 2. This is used to manufacture a laminated core pack 4 for an electrical machine (not shown), in this case a rotor core pack and a stator core pack for an electric motor. The production facility 2 contains a base frame 6 mounted stationary in a production hall (not shown in detail), as well as a punching tool 8, which is movable in the direction of the double arrow 10 in order to perform punching work in cooperation with the base frame 6. The laminated core pack 4 is manufactured from a sheet metal 12, which is provided here as an (in the technical sense endless) strip 14 and is unwound from a roll 16 and transported in a transport direction 18 (indicated by an arrow) through the production facility 2.

[0064] The production facility 2 contains (here only as an example) four punching modules 20a-d, which successively punch a sheet metal lamination 22 (only indicated in Figure 1) from the sheet metal 12 or strip 14 in four punching steps SSa-d and separate them in the punching step SSd. The sheet metal laminations 22 are successively stacked on top of one another in a collecting container 24 by a stacking module 31 and glued together with adhesive 36, as will be explained further below.

[0065] The production facility 2 contains a surface activator module 26, two printing modules 28a, b, each with (here only as an example) five printing heads 30a-e (see Figures 2-6), an adhesive activator module 32, a detector module 33, and a curing station 34 in which the stacked or bonded laminated core 4 is cured with respect to its adhesive 36 (only symbolically indicated in Figure 1). The number of print heads depends on their geometry as well as on the geometry of the stator or rotor laminated core and whether the punching process is single-row or multi-row. A transport module 38 of the production facility 2, not further designated, serves to transport the strip 14 or the separated laminated cores 22 and the laminated core 4 through the production facility 2.

[0066] In the production facility 2, the following process is now carried out to produce the disk pack 4 for the electrical machine:

[0067] 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 lamellae 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 lamellae 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 lamellae 22 using the printing heads 30a-e. In the printing steps DSa,b in the printing modules 28a,b, the adhesive 36 is printed by five print heads 30a-e each. The adhesive is applied to the lower flat side 40b or flat side 40a (shown in the figure) of each sheet metal lamella 22 to be bonded.The application is carried out by printing on a respective sheet metal lamination 22 using the print heads 30a-e in an inkjet process or inkjet technology. In a stacking step AS, the sheet metal laminations 22 separated from the strip 14 are stacked one on top of the other to form the sheet stack or lamination stack 4. This takes place in the collection container 24. Bonding is carried out 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 more detail).

[0068] 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 consecutively 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 or locally (at certain points) on it. 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).

[0069] 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. 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.

[0070] In the adhesive activation step KS, a pre-activation of the adhesive 36 is carried out so that it can optimally develop its adhesive effect when the sheet metal laminations 22 are stacked to form the lamination pack 4 in the stacking step AS or so that the curing is started.

[0071] 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.

[0072] Figure 2 shows the production of rotor laminations 22. Figure 2 shows a plan view of the production facility 2 in the direction of arrow II from Figure 1, omitting the base frame 6. The punching steps SSc,d in the punching modules 20c,d can be seen. In a variation of Figure 1, however, only a single printing module 28a with the print heads 30a-e is present here. The printing module 28a rests on the base frame 6 or punching tool 8. The printing of the adhesive 36 onto the flat side 40b (or 40a) takes place in a respective cycle step 42a-c, each of which corresponds to a further transport of the strip 14 by one unit of length LE. The punching steps SSa-d in the punching module 20a-d, on the other hand, take place when the strip 14 is at a standstill between two cycle steps 42a-c. Such a standstill in a continuous process lasts, for example, 0.2 seconds. In this example, printing does not occur during standstill, but rather during advancement of the ribbon 14.However, we can also assume 0.2 seconds for the feed rate as an example. This is how much time remains for printing.

[0073] Figure 3 shows the production of stator laminations 22 (larger than the rotor). In order to achieve optimal coverage of the strip 14 across its entire width (also sufficient for the rotor lamination) and to be able to print the entire strip area / width with adhesive 36, a total of five print heads 30a-e are arranged in two rows offset from one another in the print module 28a (print module 28b is identical in this respect, see below). In reality, this depends on the stator / rotor geometry and a two- or multi-row printing process. According to Figures 2 and 3, not only a rotor but also a stator lamination 22 can be fully coated with adhesive 36 using the same print module 28a.

[0074] Figures 2 and 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 thus in motion (dynamic process step), and the print heads 30a-e / the printing module 28a are rigidly mounted on the base frame 6. Area 48 therefore shows an inkjet 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).

[0075] The stator surface (stator lamination 22) may need to be printed with adhesive in two steps:

[0076] Figure 4, in accordance with Figure 1, therefore again shows both printing modules 28a, b, which are arranged spaced apart from one another in the transport direction 18 of the belt 14 or the sheet metal lamellae 22. In a first cycle step 42a, the printing module 28a coats a 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, whereby in this case, a gapless, seamless application of adhesive 36 actually takes place.

[0077] Figure 4 therefore shows a process variant for better surface coverage of the sheet metal cut during adhesive dosing (especially in the stator).

[0078] Figure 5 shows an example sequence of application steps in the punching sequence, here a second case: dosing in the punching step of the punching process.

[0079] Figure 5 shows an alternative printing module 28a in the production facility 2, which is not arranged stationary on the base frame 6 or the punching tool 8 like the printing modules 28a, b of Figures 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 punching tool 8. The direction of movement 44 runs parallel to the flat sides 40a, b and perpendicular to the transport direction 18. Furthermore, in contrast to Figures 2 to 4, printing does not take place during the cycle steps 42a-c, but rather in cycle pauses between respective cycle steps 42a-c, i.e., when the strip 14 is stationary relative to the base frame 6 or the punching tool 8. Printing takes place by moving the printing module 28a in one direction of the double arrow of the direction of movement 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. Figure 5 therefore shows, for example, the starting position of the print heads 30a-e (printing 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.

[0080] According to Figure 5, the sheet 12 is stationary (static process step), and the print heads 30a-e are moving. Their alternating movement occurs transversely to the transport direction 18. A similar process is used for the rotor.

[0081] 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.

[0082] Figure 6 thus shows another alternative embodiment of a printing module 28a. Here, it is also movably mounted relative to the base frame 6, but rotates around a rotational axis 46 for printing, as indicated by arrows in Figure 6. Here, too, the printing of the sheet metal lamination 22 with adhesive 36 takes place between two cycle steps 42a-c, i.e., with the strip 14 or sheet metal lamination 22 stationary relative to the base frame 6.

[0083] Here, too, the sheet 12 remains stationary (static process step). The print heads 30a-e are in motion. The print head assembly / print module 28a rotates. Here, too, an analogous process is applied to the rotor. Reference symbol

[0084] manufacturing facility

[0085] Disc pack

[0086] Basic framework

[0087] punching tool

[0088] 10 Double arrow

[0089] 12 sheets

[0090] 14 volumes

[0091] 16 rolls

[0092] 18 Transport direction

[0093] 20a-d punching module

[0094] 22 sheet metal slats

[0095] 24 collection containers

[0096] 26 Surface activator module

[0097] 28a, b pressure module

[0098] 30a-e printhead

[0099] 31 Stacking module

[0100] 32 Adhesive activator module

[0101] 33 Detector module

[0102] 34 Curing station

[0103] 36 Adhesive

[0104] 38 Transport module

[0105] 40a, b flat side

[0106] 42a-c bar step

[0107] 44 Direction of movement

[0108] 46 axis of rotation

[0109] 48 Area

[0110] LE unit of length

[0111] SSa-d punching step DSa,b printing step AS stacking step OS surface activation step

[0112] KS adhesive activation step

[0113] ES detector step

Claims

Patent claims 1 . A 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 an inkjet 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 in that the sheet (12) is provided as a strip (14) with the two flat sides (40a, b).

3. Method according to claim 2, characterized in 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 in 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 in 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 in that 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 in 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 in 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 in 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 in 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). 1 1. Method according to one of the preceding claims, characterized in 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 in 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) which is not parallel to a transport direction (18) of the sheet metal lamination (22).

13. Method according to one of claims 11 to 12, characterized in 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), each of the printing modules (28a, b) containing at least one of the print heads (30a, b), the printing modules (28a, b) being 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