Device and method for connecting sheet metal parts to form a stack of sheets

Abstract

Device and method for connecting sheet metal parts (2) into a stack of laminations (3), wherein sheet metal parts (2) are separated, in particular cut out, from an electrical steel strip (5) by means of a blanking stage (11) having a punch (13), wherein the electrical steel strip (5) has a preferably thermally activatable hot-melt adhesive lacquer layer (8), in particular a stoving lacquer layer, on at least one of its flat sides (6, 7), the separated sheet metal parts (2) are stacked and are connected to one another in a material-locking manner to form a plurality of stacks of laminations (3) by activating the hot-melt adhesive lacquer layer (8), wherein a release agent (17) is applied to the electrical steel strip (5) and / or the separated sheet metal parts (2) in order to facilitate the separation of the stacked sheet metal parts (2) into stacks of laminations (3). In order to provide favorable conditions, it is proposed that the punch (13) of the blanking stage (11) apply a fluid (17.1), in particular a liquid, as the release agent (17) to the electrical steel strip (5) and / or the separated sheet metal parts (2).

Description

Field of the Invention

[0001] The invention relates to a device and a method for connecting sheet metal parts into a stack of laminations, wherein sheet metal parts are separated, in particular cut out, from an electrical steel strip by means of a blanking stage having a punch, wherein the electrical steel strip has, on at least one of its flat sides, a preferably thermally activatable hot melt adhesive lacquer layer, in particular a baked lacquer layer, the separated sheet metal parts are stacked and are joined to one another in a material-locking manner by activation of the hot melt adhesive lacquer layer to form a plurality of stacks of laminations, and a release agent is applied to the electrical steel strip and / or the separated sheet metal parts in order thereby to facilitate the separation of the stacked sheet metal parts into stacks of laminations. Background Art

[0002] For example, it is known from WO2014089593A1 to apply a release agent to an electrical steel strip coated with a hot melt adhesive lacquer layer. This facilitates the separation of stacks of laminations from the stacked sheet metal parts. For example, before the blanking stage, the release agent is sprayed onto the electrical steel strip, and the blanking stage separates the sheet metal parts from the electrical steel strip and presses them into a stacking device.

[0003] Thus, the application of the release agent takes place in a step before the separation, which results in increased expenditure with regard to the synchronization of the application of the release agent and the control of the successive blanking tools. In addition, the electrical steel strip undergoes a movement in the longitudinal direction towards the last blanking stage after the application, which endangers the positioning of the release agent on the hot melt adhesive lacquer layer. However, the resulting imprecise application of the release agent not only makes the separation of the stacked stacks of laminations more difficult, but also causes the sheet metal parts of the stacks of laminations to have a reduced cohesion in an undesirable manner. This makes the reproducibility of the method difficult. Summary of the Invention

[0004] Therefore, the object of the invention is to take measures facilitating the separation of the stacks of laminations in order to improve the reproducibility of the method of the prior art. In addition, the method should also be carried out more simply.

[0005] The invention solves the posed object by the following features.

[0006] Since the punch of the blanking stage applies a fluid as a release agent to the electrical steel strip and / or the separated sheet metal parts, the release agent on the electrical steel strip does not move in the feed direction of the electrical steel strip. It is also possible to apply the release agent to the electrical steel strip or the separated sheet metal parts without the electrical steel strip undergoing a movement in its feed direction thereby. This additionally ensures a fixed position and in particular an exact positionability of the release agent, which is particularly advantageous if the fluid is a liquid.

[0007] This effect not only promotes the precise separability of the stack of laminations, but also promotes the stability of the stack of laminations itself, because the release agent cannot penetrate into undesired areas of the sheet metal part or cannot be applied outside the desired areas of the electrical steel strip, and this risk exists especially if the fluid is a liquid.

[0008] The method according to the invention can thus have high reproducibility. In addition, the method is relatively easy to carry out because the application of the release agent can be simply controlled by the clock of the final blanking stage.

[0009] If the punch applies the fluid when separating out the sheet metal part, then it itself can be used as a local boundary for the application of the release agent. Therefore, the reproducibility of the method can be further improved.

[0010] If, when applying the fluid, the punch is tightly connected to the hot-melt adhesive paint layer by means of at least one cut edge and the punch thus at least partially delimits on the hot-melt adhesive paint layer the surface (F) onto which the fluid is applied, then the possibility arises that the cut edge prevents the lateral escape of the release agent. This further facilitates the safe and sufficient application of the release agent. High reproducibility can thus be achieved.

[0011] Preferably, the fluid is applied by a contact printing process. This can improve the accuracy of the application of the release agent and thus further facilitate the precise separation of the sheet metal part into the stack of laminations.

[0012] If the punch has a fluid-applying printing punch, in particular a printing pad or felt, which is movable relative to its punch bottom, then the application of the release agent can be further facilitated (even in the case of an uneven surface of the electrical steel strip or the separated sheet metal part) in order to apply a sufficient amount of release agent by means of the contact punch.

[0013] Alternatively, i.e. instead of applying the release agent in a contact manner as described above, it is conceivable to spray the fluid.

[0014] For this purpose, the punch preferably has at least one nozzle which applies the fluid with a rectangular impact surface.

[0015] The invention also poses the following task, namely to provide a device for connecting sheet metal parts to form a stack of laminations, which device has a simplified structure but can still separate the sheet metal parts firmly connected to each other into the stack of laminations.

[0016] The invention solves the posed task by the following features.

[0017] By providing the punch of the blanking stage with a device configured to apply a release agent, especially a fluid configured as a liquid, to the electrical steel strip and / or the separated sheet metal parts, it is ensured that only the sheet metal parts responsible for precisely separating the interconnected sheet metal parts to form a lamination stack are coated. This measure is also relatively easy to implement on the punch, which simplifies the structure of the equipment.

[0018] The punch preferably has a punch bottom and at least one cutting edge protruding from the punch bottom and configured to form a sealing surface for the fluid together with the hot-melt adhesive paint layer. Thus, in addition to the separation function, the cutting edge is also used to limit the application of the fluid to the hot-melt adhesive paint layer. This further facilitates the safe and sufficient application of the release agent. High reproducibility can thereby be achieved. High reproducibility can thereby be achieved.

[0019] If the device has a printing punch, especially a printing pad or felt, for applying the fluid that is movable relative to the punch, then the equipment can achieve particularly high coating accuracy, where the printing punch is arranged in a recess on the punch bottom of the punch. According to the invention, even in the case of an uneven surface, it is possible to ensure the application of a sufficient amount of release agent by means of the contact punch.

[0020] A non-contact application of the release agent is also conceivable, in such a way that the device has a nozzle, especially a flat jet nozzle, for applying the fluid. For example, by using a centered arrangement of the device on the punch bottom, it is possible to ensure a uniform distribution of the release agent on the surface to be coated of the electrical steel strip and / or the sheet metal part. Description of the Drawings

[0021] In the drawings, the subject matter of the invention is described in detail, for example, according to an implementation variant. Among them:

[0022] Figure 1 A schematic view of a device for performing the method according to the invention is shown,

[0023] Figure 2 A detailed view of the blanking stage in another movement position of the device is shown Figure 1 of the blanking stage,

[0024] Figure 3 A top view of the detailed view is shown Figure 2 and

[0025] Figure 4 A top view of different shaped sheet metal parts is shown Figure 2 of. Detailed Description of the Invention

[0026] According to Figure 1Schematically shown is a device 1 for carrying out the method according to the invention. The device 1 is used to stack free-blanked sheet metal parts 2 into a stack group 3. For this purpose, an electrical steel strip 5 is unwound from a coil 4, and the electrical steel strip has a thermally cured hot-melt adhesive paint layer 8 applied over the entire surface on one of its flat sides 6, 7 in the embodiment. Obviously, layers made of hot-melt adhesive paint can also be provided equally over the entire surface on both flat sides 6 and 7.

[0027] This thermally cured or thermally curable hot-melt adhesive paint is also known under the name "baked paint". For example, the hot-melt adhesive paint can have an epoxy resin matrix. The hot-melt adhesive paint preferably has a hardener, for example a bisphenol-based epoxy resin system with a dicyandiamide group. In particular, the mentioned hot-melt adhesive paint can be a bisphenol A epichlorohydrin resin system with dicyandiamide as the hardener. This two-stage curing epoxy resin system is in the B state on the electrical steel strip. Therefore, the partially crosslinked hot-melt adhesive paint is still reactive. By inputting heat, the hot-melt adhesive paint in the B state further reacts and can thus be converted into a fully crosslinked C state, which is also called baking. Usually, the thickness of this partially crosslinked hot-melt adhesive paint layer is a few micrometers.

[0028] With the blanking tool 9, a plurality of sheet metal parts 2 are separated from the electrical steel strip 5 coated with hot-melt adhesive paint. As is usually mentioned, this is separation, such as cutting out, cutting off, shearing, slicing, dividing, punching out, etc. As can be seen from Figure 1 further, the blanking tool 9 (for example, here is a continuous blanking tool or a continuous compound tool) performs separation with multiple strokes. The blanking tool 9 can therefore have more than two blanking stages, which are not shown in the drawings.

[0029] Using the first blanking stage 10, the electrical steel strip 5 is prepared for free blanking. The method is, for example, separating out components so as to form voids on the stack group 3. This preprocessing of the electrical steel strip also prepares the sheet strip for separating out the sheet metal parts 2.

[0030] Using the second blanking stage 11, the sheet metal parts 2 are then separated from the electrical steel strip 5 by separation. Such separation can (for example, as mentioned) be cutting out, cutting off, shearing, slicing, dividing, punching out, etc.

[0031] The first blanking stage 10 has a punch 12 and the second blanking stage 11 has a punch 13, which belong to the upper tool 9.1 of the blanking tool 9. The punches 12 and 13 interact with the corresponding dies 14, 15 of the lower tool 9.2 of the blanking tool 9.

[0032] With the aid of the second blanking stage 11, the separated sheet metal parts 2 are pushed into or stacked in the stacking device 16 by the pressing of the upper tool 9.1. For this purpose, the stacking device 16 has guides in the lower tool 9.2. A holder (not shown in detail) is also provided in the guides.

[0033] The stacking device 16 can be actively heated in order to thermally activate preferably a potential hot-melt adhesive lacquer layer 8 and to establish an adhesive connection or a material-locking connection between the sheet metal parts 2, i.e., to convert the thermally curable hot-melt adhesive lacquer layer into the C state. It is conceivable here that the material-locking connection (which is also referred to as baking the sheet metal parts 2 to form

[0034] a stack group 3) is achieved in another tool or oven or by another type of energy input (as heat), which is not shown.

[0035] In order to be able to more easily separate the interconnected sheet metal parts 2 leaving the stacking device 16 into stack groups 3, the electrical steel strip 5 is prepared as follows, namely a release agent 17 is applied, more precisely to a part of the hot-melt adhesive lacquer layer 8 located on the sheet metal part 2 that is supposed to be the first or the last sheet metal part 2 of the stack group 3. In the embodiment, a liquid fluid 17.1, i.e., a liquid, is used as the release agent 17.

[0036] Differently from the prior art, this application takes place in the second blanking stage 11, i.e., in the blanking stage in which the sheet metal parts 2 are separated from or thus blanked out of the electrical steel strip 5. According to the invention, the punch 13 of the second blanking stage 11 applies the fluid 17.1 to the electrical steel strip 5 and / or the separated sheet metal parts 2. The fluid is preferably applied to the hot-melt adhesive lacquer layer 8. However, it is conceivable that the fluid is applied to the uncoated flat sides of the electrical steel strip 5 and / or the sheet metal parts 2, and / or to other coatings of the electrical steel strip 5 and / or the sheet metal parts 2.

[0037] For this purpose, the punch 13 has a device 18 which is arranged in a recess 19 on the punch bottom 13.1, i.e., in an upward arch or concave part of the punch bottom 13.1, and applies the fluid 17.1 to the hot-melt adhesive lacquer layer 8 in a contact printing process. Generally speaking, the fluid 17.1 is applied to the electrical steel strip 5 and / or the sheet metal parts 2 such that it is located between two stacked sheet metal parts 2.

[0038] The printing punch 20 (which can be partially seen in Figure 2 and in a cross-sectional view in Figure 3 is impregnated or only wetted with the fluid 17.1 and is pressed onto the hot-melt adhesive lacquer layer 8. For this purpose, the printing punch 20 moves relative to the punch 13, i.e., linearly in the direction of the electrical steel strip 5. In order to impregnate the punch 13 with the fluid, the punch can be embodied as a printing pad or felt.

[0039] So outside Figure 2 and Figure 3 As can be seen, the release agent 17 is applied by the punch 13 when the sheet metal parts 2 are separated or, in the exemplary embodiment, when the sheet metal parts are separated. The surrounding cut edge 13.2 of the punch 13 thus seals the contact printing, which prevents the release agent 17 from escaping. Thus, a cavity is formed between the punch base 13.1 and the surrounding cut edge 13.2, which facilitates the contact printing and also ensures particularly precise printing. Thus, high reproducibility is ensured so that the fluid 17.1 is only provided on the desired surface F.

[0040] The same applies to Figure 4 The sheet metal part 2 is shaped differently, for example as a rotor. Here too, the fluid 17 . 1 is applied only to the desired surface F by means of the device 18 .

[0041] The laminated core 3 can be used, for example, as a stator or rotor in an electric machine. However, other uses of such a laminated core (for example, as a core for a transformer, a coil, etc.) are also conceivable.

Claims

1. A method for connecting sheet parts (2) into a stack (3), wherein, A sheet part (2) is separated from an electrical steel strip (5) by means of a second blanking stage (11) having a punch (13), wherein the electrical steel strip (5) has a hot-melt adhesive paint layer (8) on at least one of its flat sides (6, 7), the separated sheet parts (2) are stacked and are joined to one another in a material-locking manner to form a plurality of lamination groups (3) by activating the hot-melt adhesive paint layer (8), wherein a release agent (17) is applied to the electrical steel strip (5) and / or the separated sheet parts (2) in order to thereby facilitate the separation of the stacked sheet parts (2) into lamination groups (3), characterized in that the punch (13) of the second blanking stage (11) applies a fluid (17.1) serving as the release agent (17) to the electrical steel strip (5) and / or the separated sheet parts (2).

2. The method according to claim 1, characterized in that The punch (13) applies the fluid (17.1) when separating the sheet part (2).

3. The method according to claim 2, characterized in that, The punch (13) is tightly joined to the hot-melt adhesive paint layer (8) by means of at least one cutting edge (13.2) when applying the fluid (17.1), and thus at least partially delimits a surface (F) on the hot-melt adhesive paint layer on which the fluid (17.1) is applied.

4. The method according to any one of claims 1 to 3, characterized in that The fluid (17.1) is applied by means of a contact printing process.

5. The method according to claim 4, wherein The punch (13) has a printing punch (20) for applying the fluid (17.1) which is movable relative to its punch bottom (13.1).

6. The method according to any one of claims 1 to 3, characterized in that, The fluid (17.1) is sprayed.

7. The method according to claim 6, wherein The punch (13) has at least one nozzle which applies the fluid (17.1) with a rectangular impact surface.

8. The method according to claim 1, wherein The hot-melt adhesive paint layer (8) is a stoving lacquer layer.

9. The method according to claim 1, characterized in that The fluid (17.1) is liquid.

10. The method according to claim 5, characterized in that The printing punch (20) is a printing pad or felt.

11. An apparatus for joining sheet parts (2) to form lamination groups (3), the apparatus having: a blanking tool (9) having a second blanking stage (11) with a punch (13), the second blanking stage being for separating sheet parts (2) from an electrical steel strip (5) coated on at least one of its flat sides (6, 7) with a hot-melt adhesive paint layer (8), a stacking device (16) for stacking the separated sheet parts (2) to form a plurality of lamination groups (3), and a device (18) having a release agent and configured to apply the release agent to the electrical steel strip (5) and / or the separated sheet parts (2) in order to thereby facilitate the separation of the stacked sheet parts (2) into lamination groups (3), characterized in that the punch (13) of the second blanking stage (11) has a device (18) configured to apply a release agent (17) configured as a fluid (17.1) to the electrical steel strip (5) and / or the separated sheet parts (2).

12. The device according to claim 11, characterized in that, The punch (13) has a punch bottom (13.1) and at least one cutting edge (13.2) which projects from the punch bottom (13.1) and is configured to form a sealing surface for the fluid (17.1) together with the hot-melt adhesive paint layer (8).

13. The device according to any one of claims 11 to 12, characterized in that, The device (18) has a printing punch (20) for applying the fluid (17.1) which is movable relative to the punch (13), wherein the printing punch (20) is arranged in a recess (19) on the punch bottom (13.1) of the punch (13).

14. The device according to any one of claims 11 to 12, characterized in that, The device (18) has a nozzle for applying the fluid (17.1).

15. The device according to claim 11, characterized in that, The fluid (17.1) is liquid.

16. The device according to claim 13, characterized in that, The printing punch (20) is a printing pad or felt.

17. The device according to claim 14, characterized in that, The nozzle is a flat jet nozzle.

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