Method for laminating sheet metal parts made of electrical steel strips or electrical steel sheets into at least one laminated core having at least one cooling channel

Abstract

The invention relates to a method for laminating sheet metal parts (4) made of electrical steel strips (3) or electrical steel sheets into at least one laminated core (2) having at least one cooling channel (2a). In order to obtain a leak-free cooling channel (2a), it is proposed that the cooling channel (2a) of the pre-bonded laminated core (2) is subjected to a sealing test (11) and, in the event of a leak being detected, a second pressure (P2) is applied to the adhesive (8) of the stacked sheet metal parts (4) in the axial direction (A) of the stacked sheet metal parts (4) in order to thereby produce the required sealing.

Description

Technical Field

[0001] The invention relates to a method for stacking sheet metal parts made of electrical steel strips or sheets to form at least one laminated core having at least one cooling channel. Background Art

[0002] When manufacturing a lamination stack from sheet metal parts coated with a hot-melt adhesive layer, it is known (WO2021175875A1) that when bonding the sheet metal parts, pressure is applied to the lamination stack and thus to the hot-melt adhesive lacquer layer in the axial direction in order to thereby ensure the desired stacking height. In addition to a precise stacking height, full-surface bonding between the sheet metal parts is also essential - especially when the lamination stack is required to be pressure-resistant under liquid cooling. For example, in lamination stacks in the high-power field, such as in electric motors, these lamination stacks often have a plurality of cooling channels for this purpose, through which a liquid fluid, i.e. a coolant, flows.

[0003] If leakage occurs during the tightness test on the finished lamination stack, subsequent sealing of the cooling channels is necessary, which is relatively complex and therefore results in the rejection of the finished bonded lamination stack in most cases. Summary of the invention

[0004] The invention is therefore based on the object of modifying the method described at the outset for producing a laminated core with cooling channels such that a laminated core with liquid-tight cooling channels can be produced reproducibly.

[0005] The invention achieves the stated object by means of the features of claim 1 .

[0006] Unlike the prior art, by testing the sealing of the cooling channel on the pre-bonded lamination stack (rather than on the final bonded lamination stack as in the prior art), measures can still be taken at the bonding between the sheet metal parts. Therefore, in other words, in the event of a leak, a second pressure can be applied to the sheet metal parts stacked one above the other in the axial direction so as to act on the defects of the adhesive connection, that is, to eliminate these defects. This is possible because the gel point of the polymer of the adhesive is not reached or exceeded for the pre-bonding. Therefore, acting on the adhesive in the pre-bonded state with the pressure according to the invention can still have an impact on the bonding effect of the adhesive. For example, a larger area of ​​contact and / or contact surface can be better dissolved by the solvent of the adhesive, and / or the polymer chains of the adhesive can be made more tightly connected, etc., so as to produce the required sealing at the bonding of the sheet metal parts. Therefore, unlike the prior art, measures can be taken on the lamination stack before the final bonding of the sheet metal parts to eliminate defects in the sealing of the liquid channel, so that a liquid-tight lamination stack can be manufactured in a reproducible manner by means of the method according to the invention.

[0007] Preferably, the heat-activatable adhesive has a first temperature for the pre-bonding, which is greater than the glass transition temperature of the adhesive and less than the activation temperature of the adhesive. This prevents the heat-activatable adhesive from adhering to the joint surface but not being converted into a cured state, for example by crosslinking, during the pre-bonding process. Thus, in the event of a leak being detected, the adhesive connection can still be acted upon in order to produce the desired seal at the finally bonded laminate stack in the method. This final bonded state can be achieved by finally heating the heat-activatable adhesive to a second temperature greater than or equal to the activation temperature and thereby finally bonding the sheet metal parts to one another.

[0008] The heat-activatable adhesive can be, for example, a hot-melt adhesive lacquer, which is also known by the name of a baking lacquer. In the case of a hot-melt adhesive lacquer, the activation temperature is the bonding temperature of the hot-melt adhesive lacquer.

[0009] Preferably, in the leak test for detecting leaks, a gaseous fluid is introduced into the cooling channel. For example, a test gas (Prüfgas) may be particularly suitable for this. In particular, the use of a gaseous fluid in the leak test ensures that the method is fast and suitable for in-line production of the lamination stack.

[0010] If the gaseous fluid contains helium and / or hydrogen, even small leaks can be detected in a relatively short time. The gaseous fluid is, for example, a nitrogen-hydrogen mixture (Formiergas).

[0011] The test time of the leak test can be further reduced if a positive pressure acts on the pre-bonded laminated core inside the cooling channel to be tested for leak tightness and / or a negative pressure acts on the pre-bonded laminated core outside the cooling channel to be tested for leak tightness. In particular, a positive pressure in the range of 0.1 bar to 2 bar in the cooling channel to be tested may be suitable for this, i.e. a pressure of 0.1 bar to 2 bar higher than the pressure acting on the laminated core from the outside.

[0012] Preferably, the pre-bonded lamination stack is introduced into a vacuum chamber during the leak-tightness test in order to further increase the sensitivity of the detection of even the smallest bonding defects on the pre-bonded lamination stack. This can further increase the reproducibility of the method for producing lamination stacks with liquid-tight cooling channels.

[0013] If a leak rate of no more than 10 -4 mbar l / s *l / s) (measured according to DIN EN 1779), it can be proven to be sufficiently liquid-tight. -3 mbar l / s to 10 - 4 Leak rates in the mbar l / s range can be detected – this ensures that test times are relatively short.

[0014] When the second pressure is applied, the adhesive preferably has the first temperature, in order to utilize this state of the adhesive to be able to eliminate any defects in the adhesive bond more quickly and more reproducibly.

[0015] If the application of the second pressure comprises at least one pressure pulse, the reliability of the process of eliminating defects in the bonding of the sheet metal parts that lead to leakage is further increased. Thus, for example, even differences in the rheological properties of the hot melt adhesive layer can be overcome by the pressure pulses, which can further promote the full-area connection between the sheet metal parts by forming a more uniform boundary layer.

[0016] To apply the pressure pulse, for example, the pulse pressure can be applied or relieved.

[0017] The second application of pressure may also include a plurality of pressure pulses.

[0018] Preferably, the pressure pulse is at 0.5 N / mm 2 Up to 10N / mm 2 (Newton / mm2) range of impulse pressure to load the adhesive. However, if the impulse pressure is 2N / mm 2 Up to 6N / mm 2 Within the range, it can be proven to be sufficient.

[0019] For example, the second pressure application is performed with a successive pressure pulse. This can be performed periodically, for example. This period T can be in the range of 0.1 sec to 20 sec (seconds).

[0020] Particularly simple process conditions can be obtained if the first temperature is in the range of 80° C. to 220° C. Preferably, the first temperature is in the range of 80° C. to less than 180° C. The first temperature is, for example, in the range of 100° C. to 150° C., which can keep the risk of the hot-melt adhesive lacquer being squeezed out of the bonding gap between the sheet metal parts low.

[0021] If the second temperature is in the range of 180° C. to 250° C., in particular in the range of 180° C. to 220° C., the process conditions can be further simplified, for example.

[0022] Preferably sheet metal parts are placed one above the other which have an adhesive layer on one of their planar sides. If sheet metal parts are placed one above the other which have a hot-melt adhesive layer on both of their planar sides, for example, the resistance of the laminated core to liquid cooling can be further increased, since the connection is reduced to a connecting surface between two similar joint pairs. Furthermore, it is possible that the pressure pulse can act on both viscous hot-melt adhesive layers simultaneously, which can further improve the connection between the hot-melt adhesive layers and thus the connection between the sheet metal parts.

[0023] For example, the thickness of each sheet metal part is between 0.09 mm and 0.49 mm, in particular 0.09 mm to 0.29 mm, and / or the thickness of the adhesive layer of each sheet metal part is between 2 μm and 12 μm, in particular 4 μm to 8 μm. This can create particularly favorable prerequisites for high reproducibility of the method.

[0024] For example, if sheet metal parts placed one above the other are pre-bonded over the entire surface and / or finally bonded to form a laminated core, relatively high hydraulic pressures in the cooling channels can be absorbed.

[0025] For example, if, for or in the leak test of the cooling channel, undulations are produced by embossing in an adhesive, in particular in a hot-melt adhesive lacquer, at the end side of the lamination stack, the handling of the leak test can be made easier and / or the reproducibility of the leak test can be improved. Preferably, the undulations are connected to the cooling channel and / or are arranged in sections at the end side of the lamination stack. The undulations can also surround, in particular completely surround, the cooling channel.

[0026] The relief can be produced by embossing the adhesive, in particular the adhesive layer, of the pre-bonded laminated stack. It is also conceivable to produce the relief by embossing the adhesive, in particular the adhesive layer, of the finally bonded laminated stack. This is particularly true when the laminated stack is tested for leaktightness after final bonding.

[0027] For example, if the undulations have a structure of depressions and depressions protruding from the depressions, the pressure resistance of the connection with the cooling channel can be improved.

[0028] In this case, it may prove advantageous if the structure height of the relief structure is at least 1 μm, in particular at least 2 μm.

[0029] For this purpose, the relief structure can also have a maximum structure width of at least 200 μm, in particular at least 500 μm.

[0030] It is also conceivable that the recesses have a maximum recess width of at least 50 μm, in particular at least 100 μm, between two relief structures arranged one behind the other.

[0031] Preferably, the structure width and the recess width are seen in the longitudinal extension of the relief.

[0032] This can be further improved, for example, when the relief forms a pattern with a regular structure, in particular a cyclic structure, in particular a dot pattern, a groove pattern, a grid pattern, a checkerboard pattern, a waffle pattern or a honeycomb pattern.

[0033] If the temperature of the adhesive during the embossing process is greater than the glass transition temperature of the adhesive, the relief can be more easily arranged in the adhesive. Preferably, the temperature of the adhesive here is a first temperature (temp1).

[0034] In order to further simplify the method, it is also conceivable to connect an adapter piece in which the relief is produced by embossing to the cooling channel during the leak-tightness test. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In the drawings, the subject matter of the invention is illustrated in more detail, for example, by means of variant embodiments. In the drawings:

[0036] Figure 1 A schematic diagram showing an apparatus for carrying out the method according to the invention,

[0037] Figure 1a Shown for Figure 1 An enlarged view of the parts of the equipment being tested for leak tightness.

[0038] Figure 2 A cross-sectional view showing a bonding gap between two sheet metal parts of a lamination pack causing a leak, and

[0039] Figure 3 Shown after a leak is detected and a second pressure is applied Figure 2 Cross-sectional view of the bonding gap,

[0040] Figure 4a Show Figure 1a A schematic partial view of

[0041] Figure 4b Shown with two end sides according to Figure 4a Schematic top view of an end side of a laminated core. DETAILED DESCRIPTION

[0042] according to Figure 1, an apparatus 1 is exemplarily shown, which is used to continuously manufacture a lamination stack 2. The exemplarily shown lamination stack 2 is preferably used for an electromagnetic component, such as an electric motor, and has at least one eccentrically arranged cooling channel 2a that runs through the lamination stack 2 in the axial direction. During the use of the lamination stack 2, a liquid fluid (i.e., a coolant) flows through the cooling channel 2a to cool the lamination stack 2.

[0043] In order to produce a lamination stack 2 with cooling channels 2a, a device 1 (see Figure 1 ) A plurality of sheet metal parts 4 with openings 4c are separated from the electrical steel strip 3, and after being stacked one on top of the other, the openings 4c of the sheet metal parts 4 form a cooling channel 2a in the lamination stack 2 - the cooling channel in this embodiment completely passes through the lamination stack 2 in the axial direction A of the lamination stack 2. In this embodiment, the opening 4c has a closed edge. Therefore, the outer circumference of the cooling channel 2a is completely bounded by the lamination stack 2 itself. However, it is also conceivable that the outer circumference of the lamination stack 2 has a cooling channel and therefore does not completely define the cooling channel, which is not shown in detail.

[0044] The electrical steel strip 3 for the sheet metal part 2 has, on at least one of its planar sides 3a, 3b (in this embodiment, on both planar sides), a layer 7 of adhesive 8, i.e. a thermosetting hot-melt adhesive lacquer 8a, which, for example, has an epoxy resin matrix and dicyandiamide as a crosslinking agent, covering the planar sides 3a, 3b over the entire surface area. The thermosetting or thermosetting hot-melt adhesive lacquer 8a is also referred to as a baking lacquer. For example, a catalytic baking lacquer can be used, such as a baking lacquer with a deposited coating for a faster and more thorough reaction.

[0045] The hot-melt adhesive varnish 8a on the electrical steel strip 3 is in state B. The glass transition temperature Tg of the hot-melt adhesive varnish 8a used by way of example is in the range of 65° C. to 85° C. (degrees Celsius) (measured according to ISO 11357-2). The bonding temperature of the hot-melt adhesive varnish 8a used by way of example as the activation temperature is in the range of greater than or equal to 180 degrees. However, the characteristic values ​​of the glass transition temperature Tg and / or the bonding temperature may vary accordingly with the hot-melt adhesive varnish 8a used.

[0046] The sheet metal parts 4 are separated by means of a punching tool 5, which can also be part of a sequential punching tool (not shown). Other means, such as a laser, are conceivable for separating the sheet metal parts 4. The punching tool 5 also introduces openings 4c in the sheet metal parts 4 for forming cooling channels 2a in the lamination stack 2 into the electrical steel strip 3, for example in the form of preferably circular holes, such as from Figure 2 It can be seen.

[0047] Preferably, the sheet thickness of each sheet metal part 4 is between 0.09 mm and 0.49 mm (millimeters), ie, 0.24 mm in this embodiment. The thickness of each adhesive layer 7 is between 2 μm and 12 μm (micrometers), ie, 5 μm in this embodiment. This also applies to the electrical steel strip 3 as a source of the sheet metal parts 4. It follows that the thickness of each individual sheet metal part 4 at the lamination stack 2 is in the range of 0.1 mm to 0.5 mm, ie, 0.25 mm in this embodiment.

[0048] The sheet metal parts 4 are pressed into the stacking device 6 by the punch 5a of the punching tool 5. In the stacking device 6, the sheet metal parts 4 are stacked one on top of the other, and have an adhesive layer 7, i.e., an adhesive layer formed by a hot-melt adhesive lacquer 8a, on at least one of their planar sides 4a, 4b. Thus, there is a single adhesive layer 7 between two consecutive sheet metal parts 4. In this embodiment, as also shown in FIG. Figure 3 As can be seen in FIG. 4 , the sheet metal parts 4 have a hot-melt adhesive lacquer layer 7 on both of their flat sides 4 a, 4 b. Thus, there are two adhesive layers 7 between two consecutive sheet metal parts 4 .

[0049] All sheet metal parts 4 stacked one on top of another leave the stacking device 6 as a loose laminated core 2 or are separated into a plurality of laminated cores 2 when or after leaving the stacking device 6. A laminated core 2 with loose sheet metal parts 4 is shown in FIG. Figure 1 Below the stacking device 6 in.

[0050] Subsequently, the loose laminated core 2 is subjected to further method steps, namely, it is introduced into a first oven 9 in order to thereby bring the hot-melt adhesive lacquer layer 7 of the sheet metal parts 4 stacked one above the other to a first temperature temp1, which is above the glass transition temperature Tg of the hot-melt adhesive lacquer 7a and below the bonding temperature of the hot-melt adhesive lacquer 7a. A embossing device 10 with a embossing die 10a is assigned to the first oven 9, which embossing die applies an axial first pressing force P1 to the laminated core 2, namely in the axial direction A of the laminated core 2, which extends parallel to the stacking direction 6 of the sheet metal parts 4 stacked one above the other. The intensity of the first pressing force P1 is 3 N / mm 2 (Newtons per square millimeter) and is applied for 30 seconds. As a result, the sheet metal parts 4 are pre-bonded to each other over the entire surface to form a laminated group 2, wherein the adhesive 8 between the sheet metal parts 2 has not yet cured or has not yet bonded in the case of hot-melt adhesive lacquer 8a. This is because the gel point of the polymer of the hot-melt adhesive lacquer 8a has not been reached or exceeded. It is well known that when a dynamic mechanical analysis (DMA) is performed at 20°C using a parallel plate oscillating viscometer (Platte / Platte-Oszillationsviskosimeter) that conforms to ISO 6721-10, the gel point is considered to be reached when the graphs of the storage modulus G' and the loss modulus G" intersect.

[0051] As an alternative to the first oven 9, it is conceivable (but not shown) to bring the sheet metal parts 2 in the stacking device 6 to the first temperature temp1 before leaving - this can save the method step of using the first oven 9 for heating, because the sheet metal parts 4 can also be pre-bonded to each other over the entire surface to form a laminated stack 2. However, the embossing device 10 can be used to apply the first pressure P1.

[0052] The pre-bonded lamination stack 2 is then subjected to a leak test 11. In this step, the cooling channels 2a of the pre-bonded lamination stack 2 are checked for leaks. Figure 1a Schematically shown, the lamination stack 2 is introduced into a vacuum chamber 12, and furthermore, a pipeline 13 is connected in a gastight manner to the cooling channel 2a of the lamination stack 2. The cooling channel 2a is filled with a test gas as a gaseous fluid 14 via the pipeline 13. In the vacuum chamber, the gaseous fluid 14 escaping from the cooling channel 2a can be detected as a leak by a mass spectrometer 15 connected to the vacuum chamber 12.

[0053] Therefore, at 10 -3 mbar l / s to 10 -4 Measures are taken at leakage rates in the mbar l / s range, so that the required tightness is thereby produced at the laminated core 2. For this purpose, the pre-bonded laminated core 2 is introduced into a further embossing device 16 with a embossing die 16a. In this method step, a second pressure P2 is applied to the adhesive 8 of the laminated core 4 stacked one above the other in the axial direction A of the laminated core 4 stacked one above the other, in order to produce the required tightness.

[0054] The second pressure P2 is sufficient to achieve a complete bonding of the two adhesive layers 7 to each other, so as to thereby eliminate the open area 16 between the hot-melt adhesive lacquer layers 7 and thus eliminate the adhesive gap, such as can be combined with Figure 2 exist Figure 3 Therefore, Figure 3 It can be clearly seen in FIG. 8 how the adhesive 8 surrounding the cooling channels 2 a does not contain these open areas 16. As a result, a pre-bonded laminated core 2 with leak-free cooling channels 2 a is obtained in a reproducible manner.

[0055] Subsequently, the sheet metal parts 4 are baked over their entire surface to form a laminated stack 2 or the hot-melt adhesive varnish 7a is thereby converted into a C state. Thus, a leak-free state of the laminated stack 2 is ensured by the final bonding. For the final bonding, the laminated stack 2 is introduced into another oven 17, where the adhesive 8 of the laminated stack 2 is finally heated to a second temperature temp2 that is greater than or equal to the bonding temperature of the hot-melt adhesive varnish 7a of the hot-melt adhesive varnish layer 7, so that the sheet metal parts stacked on each other are bonded together within a sufficiently long baking time. In this step, a constant pressure can also be applied to the sheet metal parts, for example, in order to set the stacking height of the laminated stack 2. For example, when the possible pressure load acting on the laminated stack 2 is 0.3 N / mm 2 In this case, the second temperature temp2 is 200° C. (200 degrees Celsius) and the baking time is 1 minute.

[0056] It is further conceivable (but not shown) that before the pre-bonded laminated stack 2 is subjected to a sealing test 11, the stacking height is detected by means of a measuring method and, if the detected stacking height is below a tolerance range, at least one additional sheet metal part 4 is applied to the end sides 2b, 2c of the laminated stack 2 so as to adapt the stacking height to a height within the tolerance range of a predetermined target stacking height.

[0057] As in Figure 1 and Figure 1a It can also be seen that during the second pressure P2 the laminated core 2 and also its adhesive 8 are at the first temperature temp1. This further improves the defect-free pre-bonding of the sheet metal parts 4. The first temperature temp1 is in the range of 80°C to 220°C, ie 120°C.

[0058] The pre-bonded laminated core 2 is subjected to the second pressure P2 in a special manner. 20 And then unload the pulse pressure P 20 To apply pressure pulses to the lamination stack 2. This operation is repeated several times, thereby generating a periodic pulse sequence.

[0059] For this purpose, the pressing device 16 applies a force P to the lamination stack 2. 20 The second pressure P2 or load is 0.5N / mm 2 Up to 20N / mm 2 In the range (5N / mm in this embodiment) 2 ) of pulse pressure. With the same duration t 1 and t 2 The load strength is P 20 The second pressure P2 and the unloading strength is P 20The second pressure P2 of , the resulting period T is in the range of 0.1 seconds to 20 seconds, in this embodiment 2 seconds. This ensures a high reproducibility when manufacturing the lamination stack 2 with liquid-tight cooling channels 2a.

[0060] In order to be able to seal the line 13 to the laminated core 2 in a more reproducible manner, an undulation 19 is produced in the adhesive 8 by embossing on this end side 2b of the laminated core 2, surrounding the cooling channel 2a and connected to it, as in Figure 4a and Figure 4b Can be seen in.

[0061] To achieve this, an adapter 18, in particular made of stainless steel, is provided at the connection end of the line 13 and has a grid-shaped embossing on its front side 18a. By pressing the adapter 18 onto the laminated core 2, a grid-shaped relief 19 is produced on the adhesive 8 (in this embodiment, the hot-melt adhesive lacquer 8a), more precisely on the outer adhesive layer 7 of the sheet metal part 4 located on the relevant end sides 2b, 2c of the laminated core 2. However, this relief 19 can be produced in a different way and / or can be produced or already exist before the adapter 18 is connected.

[0062] As in Figure 4a and Figure 4b As can be seen in FIG. 1 , the relief 19 has depressions 20 and relief structures 21 protruding from these depressions 20 .

[0063] In the schematic Figure 4a and Figure 4b In a different embodiment, the relief structure 21 has a structure height dr of 7 μm and a maximum structure width sbr of 585 μm. The recess 20 has a maximum recess width kp of 278 μm between two successively arranged relief structures 22 .

[0064] Embossing can be performed in a particularly robust and reproducible manner if the adhesive 8 has a temperature during the embossing process which is greater than the glass transition temperature Tg of the adhesive 8. Preferably, this temperature is a first temperature temp1.

[0065] Advantageously, the stainless steel surface of the adapter 18 also allows the adapter 18 to be non-destructively separated from the laminated core 2 , for example when the laminated core 2 is removed from the vacuum chamber 12 after the leak test 11 .

[0066] Generally speaking, "particularly" can be translated as "more particularly" in English. Features beginning with "particularly" should be considered as optional features that can be omitted and therefore do not constitute limitations on, for example, the claims. The same applies to "preferably", which is translated as "preferably" in English.

Claims

1. A method for stacking sheet metal parts (4) made of electrical steel strips (3) or electrical steel sheets to form at least one lamination stack (2) with at least one cooling channel (2a), wherein: Placing the sheet metal parts (4) one above the other, wherein the sheet metal parts each have at least one opening (4c) for forming the cooling channel (2a) and have a curable adhesive (8) on at least one of the planar sides (4a, 4b) of the sheet metal parts, so that the opening (4c) forms the cooling channel (2a) extending in the lamination stack (2); Applying a first pressure (P1) to the sheet metal parts (4) stacked one above the other in the axial direction (A) of the sheet metal parts (4) stacked one above the other, and pre-bonding the sheet metal parts stacked one above the other to form a laminated stack (2) by means of the curable adhesive (8); The cooling channel (2a) of the pre-bonded lamination stack (2) is tested for tightness (11) and, if leakage is detected, a second pressure (P2) is applied to the sheet metal parts (4) stacked one on top of the other in the axial direction (A) in order to thereby produce the required tightness; as well as The pre-bonded laminate stack (2) is finally bonded by curing the curable adhesive (8).

2. The method according to claim 1, It is characterized in that For the pre-bonding, the heat-activatable adhesive (8) has a first temperature (temp1), which is greater than the glass transition temperature (Tg) of the adhesive (8) and less than the activation temperature of the adhesive (8), in particular, the adhesive is a hot-melt adhesive lacquer (8a), in particular, the first temperature (temp1) is less than the bonding temperature of the hot-melt adhesive lacquer (8a); as well as For the final bonding, the heat-activatable adhesive (8) is finally heated to a second temperature (temp2) greater than or equal to the activation temperature, and the sheet metal parts (4) are thereby finally bonded to each other. In particular, the second temperature is greater than or equal to the bonding temperature of the hot-melt adhesive lacquer (8a).

3. The method according to claim 1 or 2, It is characterized in that In the leak test (11) for detecting leakage, a gaseous fluid (14), in particular a test gas, is introduced into the cooling channel (2a).

4. The method according to claim 3, It is characterized in that The gaseous fluid (14) comprises helium and / or hydrogen, and in particular, the gaseous fluid is a nitrogen-hydrogen mixed gas.

5. The method according to claim 3 or 4, It is characterized in that Inside the cooling channel (2a) whose sealing is to be tested, a positive pressure acts on the pre-bonded laminated stack (2), in particular, the positive pressure is in the range of 0.1 bar to 2 bar; and / or, outside the cooling channel (2a) whose sealing is to be tested, a negative pressure acts on the pre-bonded laminated stack.

6. The method according to any one of claims 1 to 5, It is characterized in that In the leak-tightness test (11), the pre-bonded laminated core (2) is introduced into a vacuum chamber (12).

7. The method according to any one of claims 1 to 6, It is characterized in that In the sealing test (11), the maximum leakage rate is 10 -4 mbar l / s leak detection, in particular, for leak rates of 10 -3 mbar l / s to 10 -4 Leaks in the mbar l / s range can be detected.

8. The method according to any one of claims 2 to 7, It is characterized in that When the second pressure (P2) is applied, the adhesive (8) has the first temperature (temp1).

9. The method according to any one of claims 1 to 8, It is characterized in that Applying the second pressure (P2) has at least one pressure pulse (P 20 ), in particular, applying the second pressure has multiple pressure pulses.

10. The method according to claim 9, It is characterized in that The pressure pulse (P 20 ) Load the adhesive (8) at 0.5 N / mm 2 Up to 10N / mm 2 Pulse pressure within the range of and / or in succession to successive pressure pulses (P 20 ) to apply the second pressure (P2), in particular, the pressure pulse (P 20 ) Load the adhesive (8) at 2N / mm 2 Up to 6N / mm 2 and / or, in particular, periodically with successive pressure pulses (P 20 ) to apply the second pressure (P2).

11. The method according to any one of claims 1 to 10, It is characterized in that The first temperature (temp1) is in the range of 80°C to 220°C, preferably, the first temperature is in the range of 80°C to less than 180°C, and in particular, the first temperature is in the range of 100°C to 150°C.

12. The method according to any one of claims 1 to 11, It is characterized in that The second temperature (temp2) is in the range of 180°C to 250°C, and in particular, the second temperature is in the range of 180°C to 220°C.

13. The method according to any one of claims 1 to 12, It is characterized in that The following sheet metal parts (4) are stacked one on top of another, wherein the sheet metal parts have an adhesive layer (7) on one of the planar sides (4a, 4b) of the sheet metal parts, in particular, the sheet metal parts have an adhesive layer (7) on both planar sides (4a, 4b) of the sheet metal parts, in particular, the adhesive layer (7) consists of a hot-melt adhesive lacquer (8a).

14. The method according to any one of claims 1 to 13, It is characterized in that The thickness of each sheet metal part (4) is between 0.09 mm and 0.49 mm, in particular, the thickness of each sheet metal part is between 0.09 mm and 0.29 mm, and / or the thickness of the adhesive layer (7) of each sheet metal part (4) is between 2 μm and 12 μm, in particular, the thickness of the adhesive layer (7) of each sheet metal part (4) is between 4 μm and 8 μm.

15. The method according to any one of claims 1 to 14, It is characterized in that The sheet metal parts (4) stacked one on top of another are pre-bonded over the entire surface and / or finally bonded to form a laminated core (2).

16. A method, in particular according to any one of claims 1 to 15, It is characterized in that In order to carry out the tightness test (11) of the cooling channel (2a) or when carrying out the tightness test (11) of the cooling channel, an undulation (19) is produced in the adhesive (8) by embossing on the end sides (2b, 2c) of the laminated core (2), in particular the adhesive is a hot-melt adhesive lacquer (8a), in particular the undulation surrounds the cooling channel (2a) and / or is connected to the cooling channel.

17. The method according to claim 16, It is characterized in that The undulating portion (19) has a depression (20) and an undulating portion structure (21) protruding from the depression (20).

18. The method according to claim 17, It is characterized in that The undulating structure (21) has a structure height (dr) of at least 1 μm, in particular, the undulating structure has a structure height of at least 2 μm, and / or the undulating structure (17) has a maximum structure width (sbr) of at least 200 μm, in particular, the undulating structure (17) has a maximum structure width of at least 500 μm.

19. The method according to claim 17 or 18, It is characterized in that The depression (20) has a maximum depression width (kp) of at least 50 μm, in particular at least 100 μm, between two relief structures (22) arranged one behind the other.

20. The method according to any one of claims 16 to 19, It is characterized in that The undulating portions (19) form a pattern with a regular structure, in particular, the regular structure is a cyclic structure, in particular, the undulating portions form a convex dot pattern, a groove pattern, a grid pattern, a chessboard pattern, a waffle pattern or a honeycomb pattern.

21. The method according to any one of claims 16 to 20, It is characterized in that The temperature of the adhesive during the embossing process is greater than the glass transition temperature (Tg) of the adhesive (8), and / or, in the sealing test, an adapter (18) is connected to the cooling channel (2a), and the adapter produces the undulation (19) by embossing.

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