Method for stacking sheet metal parts made of electrical steel strips or electrical steel sheets into stack of sheets

Abstract

The invention relates to a method for laminating sheet metal parts (4) made of electrical steel strips (3) or electrical steel sheets into a laminated core (2). In order to achieve advantageous process conditions, it is proposed that a pressure (P) is applied to the hot melt adhesive paint layer (7) in the axial direction (A) of the sheet metal parts (4) stacked on top of each other by means of a pressure pulse (10) a plurality of times in such a way that the pulse pressure (P10) is applied or the pressure pulse (P10) is unloaded in order to apply the pressure pulse (10).

Description

Technical Field

[0001] The invention relates to a method for stacking sheet metal parts made of electrical steel strips or sheets into a stack of sheets, in which the sheet metal parts are stacked one on top of the other, the sheet metal parts having a hot-melt adhesive lacquer layer, in particular a self-adhesive lacquer layer, on at least one of their planar sides; the hot-melt adhesive lacquer layers of the stacked sheet metal parts are heated and pressure is applied in the axial direction of the stacked sheet metal parts at a first temperature, the first temperature being higher than the glass transition temperature of the hot-melt adhesive lacquer of the hot-melt adhesive lacquer layer and lower than the bonding temperature (Verbackungstemperatur) of the hot-melt adhesive lacquer of the hot-melt adhesive lacquer layer; and the hot-melt adhesive lacquer layers of the sheet metal parts are subsequently finally heated to a second temperature greater than or equal to the bonding temperature of the hot-melt adhesive lacquer, and the sheet metal parts are thereby bonded to each other due to the heat. Background Art

[0002] When manufacturing a laminated core 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 laminated core and thus to the hot-melt adhesive layer in the axial direction in order to thereby ensure the desired stacking height. In addition to the precise stacking height, full-surface bonding is also required between the sheet metal parts - in particular when the laminated core is required to be pressure-resistant during liquid cooling, full-surface bonding is required between the sheet metal parts - this is especially true in the high power range (for example in electric motors). Summary of the invention

[0003] Therefore, the object of the present invention is to improve the method for manufacturing a lamination stack of the type described at the beginning so that a lamination stack resistant to liquid cooling can be manufactured with improved reproducibility. In addition, the method should be easy to operate and do not require additional work.

[0004] The invention achieves the stated object by means of the features of claim 1 .

[0005] If the hot-melt adhesive lacquer layer is pressed several times by means of pressure pulses in the axial direction of the sheet metal parts stacked on top of each other, the interfacial properties of the hot-melt adhesive lacquer layer can be prepared for full-surface bonding. This is also the case even if there are temperature differences at the hot-melt adhesive lacquer layer. It is also conceivable to overcome differences in the rheological properties of the hot-melt adhesive lacquer layer by means of the pressure pulses themselves, which can further promote full-surface bonding between the sheet metal parts by forming a more uniform interfacial layer. For this purpose, the pressure pulses can be applied, for example, by loading or unloading the pulse pressure.

[0006] The method thus makes it possible to produce a reproducible, liquid-tight connection between sheet metal parts, which surprisingly can even withstand particularly high hydraulic pressures. No additional or complex work steps are required for the pressure changes acting on the laminated core in the form of pressure pulses, so the method is easy to carry out and does not involve any additional effort compared to other methods in which the laminated core is subjected to pressure during baking.

[0007] Furthermore, the handling of the method can be simplified if, for applying the pressure pulse, the pulse pressure is applied accordingly and then at least partially, in particular substantially completely, the pulse pressure is relieved. Preferably, the pulse pressure is completely relieved.

[0008] The method can be further improved if the hot-melt adhesive lacquer layer is substantially free of pressure during the subsequent release of the impulse pressure.

[0009] Preferably, the method step of pulse loading is controlled to a relatively short time in that the duration of the loading pulse pressure and / or the subsequent unloading pulse pressure is in the range of 0.1 seconds to 20 seconds. This is especially true if the duration is in the range of 0.5 seconds to 5 seconds. In this way, for example, the risk of hot-melt adhesive lacquer being squeezed out of the bonding gap between the sheet metal parts can be kept low. Preferably, the duration of the loading pulse pressure is equal to the duration of the subsequent unloading pressure.

[0010] For example, the pressure pulse is 0.5N / mm 2 Up to 10N / mm 2 The pressure pulse loads the hot melt adhesive lacquer layer in the range of 2N / mm2. Preferably, the pressure pulse loads the hot melt adhesive lacquer layer in the range of 2N / mm2. 2 Up to 6N / mm 2 The pulse pressure is within a certain range, so that the risk of the hot melt adhesive varnish being squeezed out of the bonding gap between the sheet metal parts is kept to a minimum.

[0011] If the first temperature is in the range of 80° C. to 220° C., simple process conditions can be produced. Preferably, the first temperature is in the range of 80° C. to less than 180° C. If the first temperature is in the range of 100° C. to 150° C., for example, the risk of hot melt adhesive lacquer being squeezed out of the bonding gap between the sheet metal parts can be controlled to be low.

[0012] If the pressure is applied multiple times in succession by means of pressure pulses, the homogenization of the interface properties can be further improved as a result. This is especially true if the pressure is applied multiple times in a cyclic manner by means of pressure pulses.

[0013] It can also be proved to be advantageous that the hot melt adhesive lacquer layer is pressed by pressure pulses several times in a first time period of the pressure curve and by constant pressure in at least one other time period of the pressure curve. Preferably, this other time period is two to four times longer than the first time period.

[0014] Preferably, the length of this further time period is in the range of 0.5 seconds to 180 seconds, in particular in the range of 60 seconds to 120 seconds.

[0015] For example, the length of the further second time period may be in the range of 0.5 seconds to 120 seconds, in particular 60 seconds.

[0016] For example, the length of the other third time period can be in the range of 30 seconds to 180 seconds, especially 120 seconds. From a temporal point of view, the second time period is preferably before the third time period. For example, the first time period can be between this other second time period and this other third time period.

[0017] It is conceivable to subject the hot-melt adhesive lacquer layer to pressure multiple times by means of pressure pulses, so that full-surface bonding is achieved while avoiding the adhesive being squeezed out of the adhesive joint between the sheet metal parts.

[0018] 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., simple process conditions may result.

[0019] Preferably, sheet metal parts are stacked on top of each other, which have a hot-melt adhesive lacquer layer, in particular a backing lacquer layer, on both of their flat sides. This can further increase the resistance of the laminated core to liquid cooling, for example, since the joint is reduced to the connection surface between two similar joint pairs. In addition, the pressure pulse can simultaneously act on the two viscous hot-melt adhesive lacquer layers, which can further improve the connection between the hot-melt adhesive lacquer layers and thus the connection between the sheet metal parts.

[0020] Preferably, 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 hot melt adhesive lacquer layer of each sheet metal part is between 2 µm and 12 µm, in particular 4 µm to 8 µm. This allows particularly favorable preconditions for high reproducibility of the method to be achieved.

[0021] In the method, it is conceivable, for example, to apply pressure to the laminated stack, preferably the pre-bonded laminated stack, by stacking the sheet metal parts in a stacking device, exposing the hot-melt adhesive layer of the sheet metal parts to pressure in a pressure device several times by means of pressure pulses after they have left the stacking device in the form of the laminated stack, in particular the pre-bonded laminated stack, and subsequently finally heating the sheet metal parts.

[0022] Alternatively, it is conceivable that, avoiding the use of pre-bonded laminated cores, the following method steps are carried out in a pressure device: stacking the individual sheet metal parts to form a laminated core; heating the hot-melt adhesive lacquer layer of the sheet metal parts; applying pressure several times by means of pressure pulses; and, if necessary, subsequent final heating.

[0023] Preferably, the stacking height of the lamination stack is detected several times by means of a measuring method, more precisely at least in one of the time intervals generated between two temporally consecutive pressure pulses. This provides data by means of which the method can be adjusted. For example, in each case a difference is calculated from two temporally consecutively detected stacking heights; and if the calculated difference falls below, in particular for the first time below, a predefined minimum value, the application of pressure to the lamination stack by means of the pressure pulses is stopped. This makes the method more reliable. For example, the predefined minimum value can be close to zero or, for example, can also be a minimum absolute value calculated from the calculated difference.

[0024] For example, the stack height (hp) is also detected by the measuring method temporally before the first of the pressure pulses, in order to thereby be able to determine the maximum value as the first difference value (Δhp). This makes it possible, for example, to better predict the behavior of the laminated core under further pressure pulses.

[0025] Preferably, the pre-set minimum value is 10%, 5% or 2% of the first calculated difference (Δhp). For example, in a series of relatively small differences (Δhp), 10% may be advantageous, while in a series of relatively large differences (Δhp), 5% or 2% may be more advantageous. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In the drawings, the subject matter of the invention is presented in more detail, for example, with the aid of implementation variants. In the drawings: Figure 1 A schematic diagram showing an apparatus for carrying out the method of the invention, Figure 2 Show Figure 1 The pressure curve of the pre-bonded lamination stack in the axial direction, Figure 3a Shown in accordance with Figure 2Cross-sectional view of the bonding gap between two sheet metal parts of a lamination stack that has not yet been subjected to pulse pressure. Figure 3b The hot melt adhesive layer is shown in Figure 2 A cross-sectional view of the bond gap between two sheet metal parts after being subjected to an impulse pressure, and Figure 4 An alternative apparatus for carrying out the method of the invention is shown. DETAILED DESCRIPTION

[0027] according to Figure 1 and Figure 4 Devices 1 , 100 are shown, with which a laminated core 2 is produced, which is preferably used for electromagnetic components, for example for electric machines.

[0028] To this end, the first device 1 (see Figure 1 ) A plurality of sheet metal parts 4 are separated from the electrical steel strip 3. The electrical steel strip 3 is coated on two flat sides 3a, 3b with a heat-curable hot-melt adhesive lacquer layer 7, which, for example, has an epoxy resin base and dicyandiamide as a crosslinking agent. The heat-curable or thermosetting hot-melt adhesive lacquer layer 7 can be formed by a baking varnish. For example, catalyzed baking varnishes, such as baking varnishes with a deposit layer (Depotbeschichtung), can also be used to react more quickly and completely.

[0029] The hot-melt adhesive varnish 7a or the hot-melt adhesive varnish layer 7 is in state B, wherein the glass transition temperature Tg of the hot-melt adhesive varnish 7a used by way of example is in the range of 65° C. to 85° C. (degrees Celsius) (measured in accordance with ISO 11357-2). The bonding temperature of the hot-melt adhesive varnish 7a used by way of example is in the range of greater than or equal to 180 degrees Celsius. However, these characteristic values ​​of the glass transition temperature and the bonding temperature may vary depending on the hot-melt adhesive varnish 7a used.

[0030] The sheet metal parts 4 are separated by a punching tool 5, which can also be part of a continuous punching tool not shown. It is conceivable to use other devices to separate the sheet metal parts 4, such as a laser. Preferably, the thickness of each sheet metal part 4 is between 0.09 mm and 0.49 mm (millimeters), that is, 0.24 mm, and the thickness of each hot-melt adhesive lacquer layer 7 is between 2 µm and 12 µm (micrometers), that is, 5 µm. This also applies to the electrical steel strip 3 as the source of the sheet metal parts 4. As a result, the thickness of each individual lamination of the lamination group 2 is in the range of 0.1 mm to 0.5 mm.

[0031] The sheet metal parts 4 are pushed into the stacking device 6 by the punch 5a of the punching die 5. In the stacking device 6, the sheet metal parts 4 are stacked on top of each other, and these sheet metal parts have a hot melt adhesive lacquer layer 7, i.e. a baking lacquer layer, on at least one of their planar sides 4a. Figure 3a As can be seen in FIG. 4 , the sheet metal part 4 has a hot-melt adhesive lacquer layer 7 on both of its flat sides 4 a , 4 b .

[0032] In the stacking device 6, the hot-melt adhesive varnish layer 7 is brought to a temperature tv higher than the glass transition temperature Tg of the hot-melt adhesive varnish 7a thereof, namely to a temperature tv of 100°C (100 degrees Celsius). In addition, the hot-melt adhesive varnish layer 7 is loaded with a strength of 3 N / mm 2 (Newtons per square millimeter) of pressure for 30 seconds. Thus, the sheet metal parts 4 are pre-bonded into the lamination stack 2.

[0033] All sheet metal parts 4 stacked on top of one another leave the stacking device 6 as a pre-bonded laminated core 2 or are divided into pre-bonded laminated cores 2 when leaving the stacking device 6 or after leaving the stacking device 6 (this is not shown).

[0034] Subsequently, further method steps are performed on the pre-bonded laminated stack 2 - more precisely, the laminated stack 2 is introduced into a first oven 8 so that the hot-melt adhesive lacquer layer 7 of the sheet metal parts 4 stacked on each other reaches a first temperature temp1, which is higher than the glass transition temperature Tg of the hot-melt adhesive lacquer 7a of the hot-melt adhesive lacquer layer and lower than the bonding temperature of the hot-melt adhesive lacquer 7a of the hot-melt adhesive lacquer layer, and is preheated.

[0035] However, it is also conceivable (not shown in detail) to bring the sheet metal parts 2 to the first temperature temp1 in the stacking device 6 before leaving—this dispenses with the method step of using the first baking oven 8 .

[0036] In a further step, after the lamination stack 2 leaves the stacking device 6, the lamination stack is introduced into a pressure device 9, which applies an axial pressing force P to the lamination stack 2 by means of a punch 9a, i.e., applies pressure along the axial direction A of the lamination stack 2, which direction A extends parallel to the stacking direction of the sheet metal parts 4 stacked on each other. Figure 3a Two of the sheet metal parts 4 stacked on top of each other can be seen.

[0037] This is achieved in a special way - combining Figure 2 See also Figure 1 The pressure P in the cylinder or the pressure P(t). Figure 2 It can be seen that the pre-bonded laminated core 2 is subjected to pressure in its axial direction A several times (five times in this embodiment) by means of the pressure pulses 10, in that the pulse pressure P 10 And then the pressure P is relieved. This results in a periodic pulse sequence.

[0038] According to this embodiment 2, corresponding to the pulse pressure P 10 Unloading is performed, wherein it is conceivable that a small residual pulse pressure P is left 10 .

[0039] In accordance with Figure 2 It can be seen from the pressure curve P(t) that the hot-melt adhesive lacquer layer 7 is essentially free from the pressure P due to the subsequent relief.

[0040] The pressure pulse 10 shown follows a substantially rectangular course, as shown in Figure 2 Preferably, the pressure pulse 10 has a unipolar pulse shape.

[0041] By pulse pressure P 10 , reliably compensating for inhomogeneities. This is true even if the hot-melt adhesive has inhomogeneous rheological properties over the entire joining surface due to temperature differences at the respective sheet metal parts 4. According to the invention, the pressure pulse 10 makes it possible to overcome these inhomogeneities and thereby produce a laminated core 2 that is particularly resistant to liquid cooling in a particularly reproducible manner. When the hot-melt adhesive lacquer layer 7a of the flat side 4a of the sheet metal part 4 is joined to the hot-melt adhesive lacquer layer 7a of the flat side 4b of another sheet metal part 4 adjacent thereto, the pulse pressure P 10 is particularly effective, as in Figure 3a and Figure 3b As shown in .

[0042] This also improves the bond of the hot-melt adhesive varnish 7 a of the hot-melt adhesive varnish layer 7 to the bare sheet metal part 4 , which is not shown in detail.

[0043] As in Figure 2 As further shown in FIG. 1 , in the first time period 11a of the pressure curve P(t), the pre-bonded laminated stack is subjected to pulse pressures P (of the same magnitude in this embodiment) in the axial direction A of the laminated stack five times in succession by means of pressure pulses 10 having a unipolar pulse shape. 10 , which is performed periodically with a period T. Preferably, the unloading pulse pressure P 10 , the laminated core 2 is not subjected to pressure - but it is also conceivable that a constant pressing force is superimposed on the pressure pulse 10, so that the pressure pulse pressure P 10 At this time, pressure P still acts on the hot-melt adhesive lacquer layer 7, which is not shown in detail.

[0044] To generate the pressure pulse 10 , the press 9 loads the laminated core 2 with a strength P 10 The pressure P is between 0.5N / mm 2 Up to 20N / mm 2Within the range of 5N / mm2 pulse pressure P 10 The loading with pressure P and the relief of pressure P take place with the same duration t1 and t2 , which results in a period T in the range of 0.1 seconds to 20 seconds, ie, 2 seconds.

[0045] In this method step, the hot-melt adhesive lacquer has a first temperature temp1 in the range of 80° C. to 220° C., namely 120° C.

[0046] According to the minimum requirements of control or regulation technology, the unloading pulse pressure P 10 After that, the strength can be 0.1N / mm 2 The relative minimum pressure P acts, which is not shown in detail, and can represent, for example, a substantially complete unloading of the pulse pressure P 10 .

[0047] Pulse pressure P 10 It may be sufficient to achieve full-surface bonding of the two hot-melt adhesive lacquer layers 7 to one another, so as to thereby eliminate open areas 16 between the hot-melt adhesive lacquer layers 7, such as in Figure 3a As a result, the connection of the sheet metal parts 4 to one another can also be significantly improved, which in turn further increases the durability of the laminated core 2 produced by the method according to the invention.

[0048] In the optional second period 11b of the pressure curve P(t), the lamination stack 2 is pressed with a constant pressure 12b, more precisely with a pressure between 2 N / mm 2 Up to 10N / mm 2 Within the range, that is 2N / mm 2 The strength P 12b The pressure is applied continuously for 60 seconds. In terms of time, the second period 11b is before the first period 11a.

[0049] In the optional third period 11c of the pressure curve P(t), the lamination stack 2 is subjected to a pressure P at a constant pressure 12c, more precisely at a pressure between 0.5 N / mm 2 Up to 10N / mm 2 In the range of 1N / mm 2 The strength P 12c The pressure is applied continuously for 120 seconds. In terms of time, the third period 11c is after the first period 11a.

[0050] As in Figure 1 As can be seen in FIG. 1 , the laminated core 2 or the hot-melt adhesive lacquer layer 7 of the laminated core is also kept at the first temperature temp1 during the pressing. The three time periods 11 b , 11 a , 11 c mentioned are also realized by the pressure device 9 .

[0051] Subsequently, the sheet metal parts 4 are heat-bonded to form a laminated stack 2, or the hot-melt adhesive varnish 7a is thereby converted into a C state. To this end, the laminated stack 2 is introduced into a second oven 13, and the hot-melt adhesive varnish layer 7 of the laminated stack 2 is finally heated in the second oven to a second temperature temp2 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 4 are heat-bonded to each other for a sufficiently long baking time under the condition that a constant pressure is applied in the axial direction A of the stacked sheet metal parts by an oven punch 13a. For example, the second temperature temp2 is 200°C (200 degrees Celsius), the baking time is 1 minute, and the pressure applied to the laminated stack is 0.3N / mm 2 .

[0052] The method according to the invention is therefore extremely flexible and can produce pressure-resistant laminated cores 2 with high reproducibility, without the adhesive being squeezed out of the respective adhesive joints 14 between the sheet metal parts 4. As a result, there is no need to worry about droplets 15 forming outside the adhesive joints 14, either. Figure 3b Shown by dotted lines.

[0053] For example, if the sheet metal parts 4 are stacked on top of each other according to the prior art and then baked for 1 minute at 3 N / mm 2 If the laminate group 2 is directly baked to a temperature of 200 degrees Celsius under pressure in order to ensure such pressure resistance, the problem of adhesive extrusion needs to be considered.

[0054] By adjusting the number of pressure pulses, the risk of adhesive being squeezed out of the respective adhesive joint 14 between the sheet metal parts 4 is further reduced.

[0055] This can be achieved by detecting the stacking height hp of the laminated core 2 several times by means of a measuring method, more precisely in each time interval occurring before the first pressure pulse 10 and between two pressure pulses that are consecutive in time. A difference Δhp is calculated each time from two stacking heights hp that are detected consecutively in time.

[0056] The mode of action of the pressure pulse 10 can thus be estimated as follows: When the calculated difference Δhp falls below a predefined minimum value for the first time, the application of pressure P to the laminated core 2 by the pressure pulse 10 is terminated. The method is thus stopped in time before the adhesive is squeezed out of the respective adhesive joint 14 .

[0057] Depending on requirements, the predefined minimum value can be set to 10%, 5% or 2% of the first calculated difference value Δhp. Since the stack height hp is detected before the first pressure pulse 10, the first calculated difference value Δhp also represents the first value of the sequence of difference values ​​Δhp, which significantly improves the control.

[0058] exist Figure 4 An alternative device 100 is shown in . In this case, all method steps for producing the laminated core 2 from the sheet metal part 4 are carried out in a pressing device 9 .

[0059] First, individual sheet metal parts 4 are stacked to form a laminated core 2. For example, the sheet metal parts can come from a punching device (not shown in detail).

[0060] Subsequently, the hot-melt adhesive lacquer layer 7 is heated to a first temperature temp1 and subjected to pressure P, more precisely, by means of a punch 9a and a counter-support 9b. Figure 2 As described, pressure (P) is applied multiple times by means of pressure pulses (10).

[0061] Subsequently, the hot-melt adhesive lacquer layer 7 is thermally bonded and thus converted into state C by heating the hot-melt adhesive lacquer layer 7 to a temperature temp2. Figure 1 The parameters of the second baking oven 13 are set as described.

[0062] Generally speaking, "especially" can be translated as "more particularly" in English. Features beginning with "especially" should be regarded 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 into a stack (2), wherein: stacking the sheet metal parts (4) on top of each other, the sheet metal parts having a hot-melt adhesive lacquer layer (7) on at least one of the planar sides (4a, 4b) of the sheet metal parts, in particular the hot-melt adhesive lacquer layer is a baking lacquer layer; The hot-melt adhesive lacquer layer (7) of the sheet metal parts (4) stacked on each other is heated, and a pressure (P) is applied to the hot-melt adhesive lacquer layer of the sheet metal parts (4) stacked on each other in the axial direction (A) of the sheet metal parts (4) stacked on each other at a first temperature (temp1), wherein the first temperature (temp1) is higher than the glass transition temperature (Tg) of the hot-melt adhesive lacquer (7a) of the hot-melt adhesive lacquer layer (7) and lower than the bonding temperature of the hot-melt adhesive lacquer (7a) of the hot-melt adhesive lacquer layer (7); and subsequently, finally heating the hot-melt adhesive lacquer layer (7) of the sheet metal parts (4) to a second temperature (temp2) greater than or equal to the bonding temperature of the hot-melt adhesive lacquer (7a), thereby thermally bonding the sheet metal parts (4) to each other. It is characterized in that When the hot-melt adhesive lacquer layer (7) is subjected to pressure (P) in the axial direction (A) of the stacked sheet metal parts (4), the hot-melt adhesive lacquer layer is subjected to pressure (P) by pressure pulses (10) multiple times, in which the pressure (P) is applied by applying the pulse pressure (P 10 ) or unloading pulse pressure (P 10 ) to apply the pressure pulse (10).

2. The method according to claim 1, characterized in that: By loading pulse pressure (P 10 ) and then at least partially unloading the pulse pressure (P 10 ) to apply the pressure pulse (10) accordingly, in particular, by applying the pulse pressure (P 10 ) and subsequently unloads substantially all of the pulse pressure (P 10 ) to apply the pressure pulse (10) accordingly.

3. The method according to claim 2, characterized in that After unloading the pulse pressure (P 10 ), the hot-melt adhesive lacquer layer (7) is substantially not affected by the pressure (P).

4. The method according to any one of claims 1 to 3, characterized in that Loading pulse pressure (P 10 ) and / or subsequently unloading the pulse pressure (P 10 ) has a duration in the range of 0.1 s to 20 s. In particular, the loading pulse pressure (P 10 ) and / or subsequently unloading the pulse pressure (P 10 ) has a duration in the range of 0.5 seconds to 5 seconds.

5. The method according to any one of claims 1 to 4, characterized in that The pressure pulse (10) applies a pressure of between 0.5 N / mm to the hot melt adhesive lacquer layer (7). 2 Up to 10N / mm 2 The pulse pressure (P 10 ), in particular, the pressure pulse (10) loads the hot melt adhesive lacquer layer (7) with a load between 2N / mm 2 Up to 6N / mm 2 Pulse pressure within the range.

6. The method according to any one of claims 1 to 5, 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.

7. The method according to any one of claims 1 to 6, characterized in that The pressure (P) is applied multiple times by means of the pressure pulses (10) in a continuously and / or periodically manner.

8. The method according to any one of claims 1 to 7, characterized in that The hot-melt adhesive lacquer layer (7) is subjected to pressure (P) by means of the pressure pulses (10) multiple times in a first time period (11a) of the pressure curve P(t) and by means of a constant pressure (12b, 12c) in at least one other time period (11b, 11c) of the pressure curve P(t).

9. The method according to claim 8, characterized in that The length of the further time period (11b, 11c) is in the range of 0.5 seconds to 180 seconds, in particular, the length of the further time period (11b, 11c) is in the range of 60 seconds to 120 seconds.

10. The method according to any one of claims 1 to 9, characterized in that The hot-melt adhesive lacquer layer (7) is subjected to pressure (P) multiple times by means of the pressure pulses (10), so that full-surface bonding is achieved while preventing the adhesive from being squeezed out of the adhesive joint (14) between the sheet metal parts (4).

11. The method according to any one of claims 1 to 10, 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.

12. The method according to any one of claims 1 to 11, characterized in that The sheet metal parts (4) are stacked on top of each other: the sheet metal parts have the hot melt adhesive lacquer layer (7) on both of their planar sides (4a, 4b), in particular the sheet metal parts have a baking lacquer layer on both of their planar sides (4a, 4b).

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

14. The method according to any one of claims 1 to 13, characterized in that The sheet metal parts (4) are stacked in a stacking device (6); After leaving the stacking device (6) in the form of a laminated core (2), in particular in the form of a pre-bonded laminated core, the hot-melt adhesive lacquer layer (7) of the sheet metal part (4) is subjected to pressure (P) several times by means of the pressure pulses (10) in a pressure device (9); and subsequently The sheet metal part (4) is finally heated.

15. The method according to any one of claims 1 to 13, characterized in that The following method steps are carried out in the pressure device (9): The individual sheet metal parts (4) are stacked into a lamination stack (2), The hot-melt adhesive paint layer (7) of the sheet metal part is heated, applying pressure (P) multiple times by means of the pressure pulses (10), and If necessary, final heating may follow.

16. The method according to any one of claims 1 to 15, characterized in that The stacking height (hp) of the laminated core (2) is detected multiple times by means of a measuring method, more precisely, the stacking height of the laminated core is detected multiple times by means of a measuring method in at least one of the time intervals generated between two temporally consecutive pressure pulses (10); a difference (Δhp) is calculated from each two temporally consecutively detected stacking heights (hp); and, when the calculated difference (Δhp) is below a predetermined minimum value, in particular, when the calculated difference (Δhp) is below the predetermined minimum value for the first time, the application of pressure (P) to the laminated core (2) by means of the pressure pulses (10) is terminated.

17. The method according to claim 16, characterized in that The stack height (hp) is detected by means of the measuring method already in time before a first one of the pressure pulses (10).

18. The method according to claim 16 or 17, characterized in that The predetermined minimum value is 10%, 5% or 2% of the difference (Δhp) calculated first.

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