Method for connecting sheet metal parts to form a lamination stack and device for carrying out said method - Patents.com

Abstract

The present invention relates to a method for connecting lamination parts (2) to form a lamination stack (3) and to a device (1) for carrying out said method. Improved reproducibility of the method and improved reliability of the device can be achieved if the adhesive coating (20) of the separating element (18) consists of an acrylate-based UV cross-linking hot melt adhesive (HMPSA).

Description

[Technical field]

[0001] The present invention relates to a method for connecting sheet metal parts to form a lamination stack and to a device for carrying out said method. [Background technology]

[0002] To make it easier to separate the stacked sheet metal parts into a lamination stack, it is known to provide a separating element between each two sheet metal parts. These separating elements have a flat support with an adhesive coating on one side and a non-stick coating on the other side. The thermal activation of the hot melt adhesive varnish layer on the stacked sheet metal parts causes considerable thermal and mechanical loads on the separating element, which can lead to the extrusion of this adhesive varnish or parts of it and even to the failure of its separating function. This not only reduces the reproducibility of the method, but can also introduce unwanted adhesive into the device, impairing its function. Summary of the Invention [Problem to be solved by the invention]

[0003] An object of the present invention is therefore to improve the reproducibility of the method for producing lamination stacks of the type mentioned at the start. [Means for solving the problem]

[0004] The present invention achieves the object stated with the features of claim 1.

[0005] Because the adhesive coating is made of a UV-crosslinked acrylic hot melt adhesive (HMPSA), it is possible to ensure that the functionality of the dividing elements of the stack is maintained despite relatively high surface pressures and relatively high temperatures. In particular, the use of a UV-crosslinked acrylic hot melt adhesive means that there is no need to worry about the adhesive of the dividing elements being extruded, which can reliably guarantee the required quality of the produced lamination stack.

[0006] Further, 9 to 13 g / m 2 In the case of a coating having a weight per unit area in the range of 11 g / m, the risk of the adhesive coating on the support being extruded can be reduced. Nevertheless, this weight per unit area is sufficient to provide adhesion to the sheet metal part or lamination stack. Preferably, the adhesive coating has a weight per unit area of ​​11 g / m. 2 It has a weight per unit area of

[0007] This can be further improved if the adhesive coating on the support has a layer thickness in the range of 10 to 17 μm.Preferably, the adhesive coating on the support has a layer thickness in the range of 13 to 16 μm.

[0008] The mechanical stability of the dividing element in the method can be further improved if the support consists of a woven fabric, a nonwoven fabric or a film. Preferably, the support consists of a polyester film (PET film).

[0009] If the support has a support thickness in the range of 40 to 60 μm, this can already provide sufficient mechanical stability. Preferably, the film support has a support thickness of 50 μm.

[0010] Separating the sheet metal sections into lamination stacks in this manner can be made even easier if the dividing element has a non-stick coating on the flat surface of the support opposite the flat surface of the support that has the adhesive coating.

[0011] Preferably, the non-stick coating is silicone based to allow for residue-free removal from each sheet metal section or lamination stack.

[0012] For example, the non-stick coating may be crosslinked, more specifically a solvent-free silicone coating. For example, the silicone coating may be thermally crosslinked. To achieve sufficient anti-stick properties, a layer thickness of the non-stick coating in the range of 1.0 to 3.5 μm, more specifically 2.0 to 3.0 μm, may be sufficient.

[0013] Another stated object of the invention is to improve the reliability of a device for implementing the method according to the invention.

[0014] The present invention achieves the object stated with the features of claim 7.

[0015] As the adhesive coating consists of a UV-crosslinked acrylic hot melt adhesive, the adhesive of the dividing elements is extruded, which makes it possible to reduce or entirely avoid the risk of the stacking units of the device becoming stuck together, thus further improving the reliability of the device.

[0016] Another stated object of the present invention is to ensure that the separating element easily maintains separation of the lamination stack even when exposed to high surface pressures and temperatures.

[0017] The present invention achieves the object stated with the features of claim 8.

[0018] This splitting is more likely to occur when using dividing elements having a flat support with an adhesive coating consisting of a UV-crosslinked acrylic hot melt adhesive on one flat surface of the support, the dividing elements being stacked together with sheet metal parts which are connected to each other by integral bonds to form a lamination stack, despite the relatively high thermal and physical loads, particularly on the dividing elements.

[0019] This means that the adhesive coating on the support is 9-13 g / m 2 in the range of 11 g / m 2 Alternatively or additionally, the adhesive coating may have a layer thickness in the range of 10 to 17 μm, more particularly 13 to 16 μm.

[0020] In this application, the mechanical and / or thermal stability of the dividing element can also be further improved if the support consists of a woven or nonwoven fabric or film, in particular a polyester film.

[0021] If in this application the support has a support thickness in the range of 40-60 μm, more specifically 50 μm, this also makes it easier for the user to utilize the dividing element.

[0022] This will be even more true if the dividing element has a non-stick coating, more particularly a silicone-based non-stick coating, on the flat surface of the support opposite the flat surface of the support that has the adhesive coating.

[0023] For example, a crosslinked, more specifically, solvent-free silicone coating may be used as the non-stick coating. For example, the silicone coating may be thermally crosslinked.

[0024] To achieve sufficient anti-adhesive properties, a layer thickness of the non-adhesive coating in the range of 1.0 to 3.5 μm, more particularly 2.0 to 3.0 μm, may be sufficient.

[0025] Significant results can be realized when the lamination stack has dividing elements at one or both of its ends.

[0026] The dividing element may also form an electrically insulating layer.

[0027] By way of example, the subject matter of the invention is illustrated in greater detail in the figures. [Brief description of the drawings]

[0028] [Figure 1] 1 shows a partial cutaway side view of a device for implementing a method for connecting sheet metal sections to form a lamination stack. [Diagram 2] 1 shows a cross-section through a dividing element of the present subject matter. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0029] Figure 1 shows diagrammatically an embodiment of a device 1 for carrying out the method according to the invention. The device 1 is used to bring together sheet metal parts 2 to form a lamination stack 3. For this purpose, an electrical strip 5 is unwound from a coil 4 and the strip is covered entirely onto one of the flat faces 6 or 7, or, as shown in Figure 1, onto both flat faces 6, 7 with a heat-activatable and thus curable hot-melt adhesive varnish layer 8, 9.

[0030] It should be noted that generally, such heat-activatable or heat-curable hot melt adhesive varnish layers 8,9 or hot melt adhesive layers are also known by the term "backlac". For example, the hot melt adhesive varnish may be epoxy resin-based. Preferably, the hot melt adhesive varnish is a bisphenol-based epoxy resin-based with a hardener, for example a dicyandiamide-based hardener. More specifically, the above-mentioned hot melt adhesive varnish may be a bisphenol-A-epichlorohydrin resin-based with dicyandiamide as a hardener. This two-stage cured epoxy resin system is in the B-state at the electrical strip 5. As a result, the partially crosslinked hot melt adhesive varnish is still reactive. When heat is supplied, the hot melt adhesive varnish in the B-state can further react and thus turn into the fully crosslinked C-state. This is also called baking. Usually, this partially crosslinked hot melt adhesive varnish layer 8,9 has a thickness of several micrometers.

[0031] 1, a plurality of sheet metal parts 2 are punched or separated from the backlace coated electrical strip 5 using a stamping tool 10, using a progressive stamping or joining tool. It is noted that such punching can generally be cutting, cutting, separating, trimming, breaking with extrusion, etc. Extrusion from the sheet metal parts 2 is also conceivable.

[0032] As can also be gathered from figure 1, the stamping tool 10 performs the cuts in a number of strokes 11, in which an upper tool 12 cooperates with a lower tool 13. To this end, the stamping tool 10 comprises a number of stamping tables 14, 15.

[0033] With the punch 14a of the preparatory stamping table 14 of the upper tool 11, the electrical strip 5 is prepared for punching, after which a second punch 15a of a second and final stamping table 15 is inserted on the upper tool 11, whereby the sheet metal part 2 is punched out and thus separated from the electrical strip 5. For this purpose, the punches 14a, 15a cooperate with respective dies 14b, 15b of the stamping tables 14, 15 on the lower tool 13. This type of progressive cutting can be seen in particular in FIG. 1 by the fact that in the preparatory stamping, a portion 16 is separated from the electrical strip 5 in order to prepare the electrical strip 5 for punching out the sheet metal part 2.

[0034] The sheet metal parts 2 punched out with the stamping table 15 are pressed into the stacking unit 17 by the pressure of the upper tool 11 or punch 15a and are stacked there. For this purpose, the stacking unit 17 has a shaft 17a and a counter support 17b on the lower tool 13. This counter support 17b of the lower tool 13 brakes the sheet metal parts 2, as a result of which these undergo a physical and / or chemical bond under the pressure of the upper tool 11 and with the adhesive layers 8, 9 present between the sheet metal parts 2, and are thus joined in particular by thermal activation of the hot-melt adhesive layers 8, 9 between the sheet metal parts 2. For this purpose, the stacking unit 17 is actively heated. Apart from this, the lamination stack 3 can be subjected to an additional hardening step in order to further harden the integral bond between the sheet metal parts 2. This is not shown. Furthermore, there is the possibility to rotate the stacking unit 17 in order to form a divided lamination stack 3, for example from a layer with several sheet metal parts 2 positioned next to each other and stacked one on top of the other. This is likewise not shown.

[0035] In order to allow easier separation of the lamination stacks 3 emerging from the stacking unit 17 from one another, at least one dividing element 18 is stacked together with the sheet metal part 2. For this purpose, the dividing element 18 is embodied in order to reduce the adhesion of the at least one sheet metal part 2 adjacent to it to the adhesive layers 8, 9. As can be seen in FIG. 1, this realizes a reduction in the adhesive strength between the sheet metal parts 2 of adjacent lamination stacks 3. This makes it easier to divide the connected sheet metal parts 2 into lamination stacks 3 as they emerge from the stacking unit 17.

[0036] The dividing element 18, shown in an enlarged view in Figure 2, has a flat support 19 or flat substrate. An adhesive coating 20 is applied directly onto the support 19, i.e. onto the first flat surface 19a of the two flat surfaces 19a, 19b.

[0037] According to the invention, the adhesive coating 20 consists of a UV-crosslinking (UV-C) acrylic hot melt adhesive (HMPSA). It is therefore possible to withstand relatively high pressures and temperatures during baking and joining of the sheet metal parts 2 to form the lamination stack 3 into the stacking unit 17. There is therefore no need to worry about the adhesive 3 of the adhesive coating 20 being extruded. This keeps both the inner walls of the stacking unit 17 and the lamination stack 3 emerging from said stacking unit 17 free from contamination. The method according to the invention for connecting the sheet metal parts 2 to form the lamination stack 3 therefore allows the required dimensional accuracy of the lamination stack 3 to be achieved in a particularly reproducible way. Furthermore, there is no risk of adhesive build-up in the stacking unit 17 compromising the reliability of the device.

[0038] A particularly good dividing element 18 for this purpose is one having a support 19 in the form of a polyester film with a support thickness of 49.5 μm (ie about 50 μm) in order to withstand the high temperatures and pressures in the stacking unit 17 .

[0039] In an exemplary embodiment, the adhesive coating 20 has a thickness of 11 g / m 2 and a first layer thickness of 14.6 μm and thus provides sufficient adhesion to the lamination stack 3. It is therefore possible with this method to avoid inadvertent separation of the dividing element 18, which can further improve the reproducibility.

[0040] The dividing element 18 reduces adhesion to the adjacent sheet metal part 2 of another lamination stack 3, for which a silicone-based non-stick coating 21 is applied on the flat surface 19b of the support opposite to the flat surface 19a of the support on which the adhesive coating 20 is applied. In an exemplary embodiment, this non-stick coating is preferably a thermally crosslinked silicone coating, which is applied solvent-free on the flat surface 19b of the support. For this purpose, the silicone coating has a second layer thickness in the range of 2.4-2.9 μm.

[0041] As a result, the dividing element 18 remains attached to the lamination stack 3, while the dividing element 18 can be more easily separated from the other lamination stacks 3. This makes it easier to separate the stacked sheet metal parts 2 into lamination stacks 3.

[0042] As is also evident in FIG. 1, the device 1 also has a unit 22 which is used to provide the dividing element 18 between the two sheet metal parts 2. To achieve this, the unit 22 supplies the dividing element 18 in the form of a strip or sheet 18a to the second stamping table 15 below the electrical strip 5. The second stamping table 15 stamps out the sheet metal part 2 together with the dividing element 18 and thus also gives it a form which corresponds to the die 15.2. The dividing element 18 together with the sheet metal parts 2 can also be stacked. Depending on the requirements, the strip or sheet is thus supplied to the stamping table 15 in order to provide the dividing element 18 to the stacking unit 17.

[0043] However, it is also conceivable to place the dividing element 18 on the stamping tool 10 or on an electrical strip in front of a progressive stamping tool. The dividing element 18 is shown in FIG.

[0044] It should be noted that, in general, the German phrase "insbesondere" can be translated into English as "more particularly." Features beginning with "more particularly" are considered optional features, which can be omitted and thus, for example, do not limit the claims. Similarly, the German phrase "vorzugsweise" is translated into English as "preferably."

Claims

1. A method for connecting sheet metal parts (2) to form a lamination stack (3), comprising the steps of: The sheet metal part (2) is separated, more specifically removed, from the electrical strip (5) having a heat-activatable hot melt adhesive varnish layer (8, 9) on at least one flat surface (6, 7), The removed sheet metal parts (2) are stacked and integrally bonded to one another by thermal activation of the hot melt adhesive varnish layers (8, 9) to form a plurality of lamination stacks (3); When the sheet metal parts (2) are stacked, at least one dividing element (18) is added to the stack between two sheet metal parts (2) to make it easier to divide the stacked sheet metal parts (2) from each other to form a lamination stack (3), the dividing element (18) having a flat support (19) and an adhesive coating (20) on one flat surface (19a) of the support (19), The method of claim 1, wherein the adhesive coating (20) comprises a UV crosslinked hot melt acrylic pressure sensitive adhesive (HMPSA).

2. The adhesive coating (20) on the support (19) has a thickness of 9 to 13 g / m ２ In the range of 11 g / m ２ 2. The method according to claim 1, characterized in that the coating has a weight per unit area and / or a layer thickness in the range of 10 to 17 μm, more particularly 13 to 16 μm.

3. The method according to any one of claims 1 to 2, characterized in that the support (19) consists of a woven or nonwoven fabric or a film, in particular a polyester film.

4. Method according to any one of the preceding claims, characterized in that the support (19) has a support thickness in the range of 40 to 60 μm, more particularly of 50 μm.

5. The method according to any one of claims 1 to 4, characterized in that the dividing element (18) has a non-stick coating (21), more particularly a silicone-based non-stick coating, on the flat face (19b) of the support opposite to the flat face (19a) of the support provided with the adhesive coating (20).

6. 6. The method according to claim 5, characterized in that the non-stick coating (21) is a crosslinked, more particularly a solvent-free silicone coating, and / or has a layer thickness in the range of 1.0 to 3.5 μm, more particularly 2.0 to 3.0 μm.

7. The present invention relates to a stamping tool (10) having a stamping table (15) with a punch (15a) for separating sheet metal parts (2) from electrical strips (5) which are coated with a heat-activatable hot melt adhesive varnish layer (8, 9) on said at least one flat surface (6, 7), a stacking unit (17) for stacking said separated sheet metal parts (2) to form a plurality of lamination stacks (3), and a lamination unit (18) for stacking said stacked sheet metal parts (2) to form a plurality of lamination stacks (3), and a lamination unit (19) for stacking said stacked sheet metal parts (2) to form a plurality of lamination stacks (3), and a lamination unit (20) for stacking said stacked sheet metal parts (2) to form a plurality of lamination stacks (3), and a lamination unit (21) for stacking said stacked sheet metal parts (2) to form a plurality of lamination stacks (3), and a lamination unit (22) for stacking said stacked sheet metal parts (2) from said electrical strips (5) which are coated with a heat-activatable hot melt adhesive varnish layer (8, 9) on said at least one flat surface (6, 7).

7. A device for carrying out the method according to claim 1, further comprising a dividing element (18) for dividing the electrical strip (5) and a unit (22) embodied for placing the dividing element (18) on the electrical strip (5) and / or between two sheet metal parts (2), characterized in that the dividing element (18) has a flat support (19) with an adhesive coating (20) on one of its flat faces (19a), the adhesive coating (20) consisting of a UV cross-linked acrylic hot melt adhesive (HMPSA).

8. 1. Use of a dividing element (18) for making it easier to divide a lamination stack (3), the dividing element (18) having a flat support (19) having an adhesive coating (20) consisting of a UV cross-linked acrylic hot melt adhesive (HMPSA) on one flat surface (19a) of the support, the dividing element (18) being stacked together with sheet metal parts (2) which are connected to each other by integral bonds to form a lamination stack (3).

9. The adhesive coating (20) on the support (19) has a thickness of 9 to 13 g / m ２ In the range of 11 g / m ２ 9. Use according to claim 8, characterized in that it has a weight per unit area and / or a layer thickness in the range of 10 to 17 μm, more particularly 13 to 16 μm.

10. Use according to any one of claims 8 to 9, characterised in that the support (19) consists of a woven or nonwoven fabric or a film, in particular a polyester film.

11. Use according to any one of claims 8 to 10, characterized in that the support (19) has a support thickness in the range of 40 to 60 μm, more particularly of 50 μm.

12. Use according to any one of claims 8 to 11, characterised in that the dividing element (18) has a non-stick coating (21), more particularly a silicone-based non-stick coating, on a flat face (19b) of the support opposite to the flat face (19a) of the support provided with the adhesive coating (20).

13. 13. Use according to claim 12, characterised in that the non-stick coating (21) is crosslinked, more particularly a solvent-free silicone coating, and / or has a layer thickness in the range of 1.0 to 3.5 μm, more particularly 2.0 to 3.0 μm.

14. A lamination stack produced by the method of any one of claims 1 to 6, with a dividing element (18) at one end of the lamination stack (3).

15. 15. A lamination stack according to claim 14, characterized in that the dividing element (18) forms an electrical insulating layer.

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