Lamination stack arrangement

Abstract

The invention relates to a laminated core assembly (1) comprising several laminated cores (3, 5) arranged in a stacked configuration. Each pair of adjacent laminated cores (3, 5) is spaced apart by a number of electrically insulating elements (7, 9) arranged between them, each of which has a first contact surface (11) against one of the laminated cores (3, 5) and a second contact surface (13) against the other of the laminated cores (3, 5). Each contact surface (11, 13) of each insulating element (7, 9) is a surface of a hot-melt adhesive coating (17) of the insulating element (7, 9) and is bonded to the laminated core (3, 5) to which it rests by a bonding adhesive (19) that connects the contact surface (11, 13) and the laminated core (3, 5).

Description

[0001] The invention relates to a sheet metal stack arrangement with several sheet metal stacks arranged one above the other in a stack-like manner.

[0002] A sheet metal stack is understood to be a stack of electrical steel sheets that are electrically insulated from each other and connected together.

[0003] Laminated core assemblies with stacked laminated cores are used, for example, as magnetic cores in inductors whose coils are wound around the cores. The laminated cores of such an assembly are spaced apart and electrically insulated by insulating elements. These insulating elements are made, for example, of a ceramic material. The insulating elements are bonded to the laminated cores between which they are positioned using an adhesive, creating a mechanically rigid unit. Such a columnar laminated core assembly can have a diameter of more than 1000 mm, a height of more than 4000 mm, and a weight of more than 6 tons. More than 70 bonded insulating elements can be arranged between two laminated cores. Therefore, an inductor with multiple columnar laminated core assemblies can contain more than 1000 insulating elements.

[0004] A sheet metal assembly of this size cannot be manufactured in one piece. Therefore, smaller components must be pre-assembled and then built up to form the assembly, with the individual components being bonded together. During this assembly process, an adhesive, such as an epoxy adhesive, is applied to the top and bottom of the insulating elements. After curing, this adhesive creates a mechanically stable bond between the components. The manufacturing process for producing such a sheet metal assembly requires several hundred labor hours and several hundred thousand euros worth of materials.

[0005] Due to manufacturing defects or other factors, such as damage or errors in a test area, it may become necessary to disassemble a sheet metal assembly. Depending on the extent of the damage, this disassembly is very complex and requires several hundred man-hours to restore the desired condition.

[0006] When disassembling a lamination stack, mechanical forces are applied to break the adhesive bonds between the insulating elements and the laminations. Due to the mechanical forces exerted when breaking these bonds, failure fractures occur in the bonded components. Fracture can occur in the adhesive itself, but also in the insulating element. While a fracture within the adhesive is desirable, it cannot be intentionally engineered. In fact, material fractures within the insulating element occur in approximately three out of ten bonded joints. Since a lamination stack can have more than 1000 adhesive bonds, failure fractures of insulating elements are not uncommon, but rather the norm.

[0007] For example, after an insulating element breaks, remnants of the insulating element remain on both laminations between which it was located. These remnants must be removed. It is also possible that an insulating element is completely detached from a lamination but broken. In this case, the insulating element is still completely attached to a lamination, but is technically unusable and must also be removed.

[0008] To remove an insulating element or part of an insulating element from a laminated core, the insulating element is typically mechanically knocked off the surface of the core. Due to the mechanical force applied, the laminated core itself is often damaged in the process. For example, an unwanted short circuit can be created between the electrical steel sheets within the core. Adhesive residue, on the other hand, can be easily removed mechanically from laminated cores. Laser technologies can also be used for this purpose. With these laser technologies, the adhesive residue is simply removed by irradiation with laser beams, without damaging the laminated core or its structure.

[0009] Laminated cores with insulating elements or parts thereof that cannot be removed, and laminated cores damaged by the removal of insulating elements or parts thereof, or assemblies containing such laminated cores, must be replaced. This requires remanufacturing the respective laminated core or assembly. In extreme cases, the entire laminated core assembly may become unusable, necessitating a complete remanufacturing of the assembly. This incurs additional costs and is again very time-consuming.

[0010] Heating the adhesive bonds during disassembly is also counterproductive. Epoxy adhesive is typically used as the bonding agent. Epoxy adhesives have high structural strength and temperature resistance and therefore do not lose significant strength when heated.

[0011] The invention is based on the objective of providing a sheet metal stack arrangement with several stacked sheet metal stacks arranged one above the other, which is improved in particular with regard to its disassembly.

[0012] The problem is solved according to the invention by a sheet metal stack arrangement with the features of claim 1.

[0013] Advantageous embodiments of the invention are the subject of the dependent claims.

[0014] A sheet metal stack arrangement according to the invention comprises Several stacks of laminated laminations arranged one above the other, wherein two adjacent stacks of laminated laminations are spaced apart from each other by a number of electrically insulating insulating elements arranged between them, each of which has a first contact surface on one of the stacks of laminated laminations and a second contact surface on the other stack of laminated laminations, wherein each contact surface of each insulating element is a surface of a hot melt adhesive coating of the insulating element made of a hot melt adhesive and is bonded to the stack of laminated laminations to which it is attached by a bonding adhesive which joins the contact surface and the stack of laminated laminations.

[0015] The invention provides that the insulating elements arranged between two lamination stacks each have hot-melt adhesive coatings, each forming a contact surface in contact with one of the lamination stacks and bonded to that stack by a bonding adhesive. This allows the connection of each insulating element to the lamination stacks between which it is arranged to be released by heating and melting the hot-melt adhesive. After the hot-melt adhesive coatings of all insulating elements arranged between two lamination stacks have melted, the lamination stacks, previously firmly bonded to the insulating elements, can be separated from the insulating elements without damaging either the insulating elements or the lamination stacks. This enables damage-free disassembly of the lamination stack assembly and damage-free removal of lamination stacks or of assemblies comprising multiple lamination stacks.Cooling the hot melt adhesive coatings below the melting temperature of the hot melt adhesive re-solidifies the hot melt adhesive coatings and allows the insulating elements to be reused.

[0016] Hot melt adhesive coatings are heated, for example, by flowing hot air or by applying an induction current to the adjacent sheet metal stacks.

[0017] In one embodiment of the sheet metal stack arrangement according to the invention, each insulating element has a base body made of a ceramic material, the surfaces of which facing the sheet metal stacks are coated with the hot melt adhesive.

[0018] Designing the insulating elements as ceramic base bodies coated with hot melt adhesive is advantageous because ceramic materials simultaneously exhibit high electrical insulation capacity and mechanical stability.

[0019] In a further embodiment of the sheet metal stack arrangement according to the invention, the hot melt adhesive assumes a solid state of matter at the operating temperatures of the sheet metal stack arrangement.

[0020] In other words, the hot melt adhesive chosen is one that assumes a solid state at the operating temperatures of the laminated core assembly. This means that an insulating element with hot melt adhesive coatings behaves under normal operating conditions like an insulating element without such coatings. The hot melt adhesive coatings therefore do not impair the function of the laminated core assembly under normal operating conditions, but have a positive effect when the assembly needs to be disassembled.

[0021] In a further embodiment of the sheet metal stack arrangement according to the invention, the hot melt adhesive has a melting temperature of at least 130°C.

[0022] Temperatures exceeding 130°C are not typically reached by a laminated core assembly during normal operation, making hot melt adhesives with a melting point of at least 130°C suitable materials for hot melt adhesive coatings. Furthermore, a wide variety of commercially available hot melt adhesives with a melting point of at least 130°C are available.

[0023] In a further embodiment of the sheet metal stack arrangement according to the invention, the melting temperature of the hot melt adhesive is lower than the upper service temperature of the bonding adhesive.

[0024] The upper service temperature of a material is a measure of its heat resistance, that is, its resistance to high temperatures. Above the upper service temperature, the material properties change so drastically that the material no longer meets the requirements placed upon it. Because the melting temperature of the hot melt adhesive is lower than the upper service temperature of the bonding adhesive, it is ensured that the bonding adhesive is not affected by the melting of the hot melt adhesive.

[0025] In a further embodiment of the sheet metal stack arrangement according to the invention, each insulating element is designed as a circular cylinder, the base surfaces of which are the contact surfaces of the insulating element.

[0026] Designing the insulating elements as circular cylinders is particularly advantageous when the laminated core assembly is operated in an insulating oil. This is frequently the case, for example, when the laminated cores are used as the magnetic cores of an inductor, for whose windings the insulating oil serves for electrical insulation and cooling. Designing the insulating elements as circular cylinders reduces the flow resistance of the insulating elements to the insulating oil compared to other designs. This reduction in flow resistance advantageously increases the flow velocity of the insulating oil around the insulating elements, thereby improving heat transfer through the insulating oil and thus its cooling effect.

[0027] In a further embodiment of the sheet metal stack arrangement according to the invention, the hot melt adhesive and the bonding adhesive exhibit similar strengths at an operating temperature of the sheet metal stack arrangement.

[0028] Because the hot melt adhesive exhibits a similar strength to the bonding adhesive at the operating temperature of the lamination stack, the bonds between the insulating elements and the lamination stacks have a final strength equivalent to that of bonds between insulating elements and lamination stacks without hot melt adhesive coatings. This allows the use of the same bonding adhesives as in lamination stack assemblies with insulating elements that lack hot melt adhesive coatings.

[0029] In a further embodiment of the lamination stack arrangement according to the invention, the hot melt adhesive has a strength of at least 2.7 N / mm² at an operating temperature of the lamination stack arrangement.

[0030] In a further embodiment of the sheet metal stack arrangement according to the invention, each hot melt adhesive coating has a thickness in the range of 1 µm to 2 mm, preferably in the range of 1 µm to 50 µm.

[0031] An insulating element with such a hot melt adhesive coating can be processed advantageously in the same way as an insulating element without a hot melt adhesive coating.

[0032] In a further embodiment of the laminated core arrangement according to the invention, the laminated cores, possibly with the exception of a bottommost and / or topmost core, are cylindrical in shape. This is advantageous because the coils wound around the laminated cores are usually also cylindrical, as this is electromagnetically advantageous.

[0033] In a further embodiment of the sheet metal stack arrangement according to the invention, the bonding adhesive is an epoxy adhesive.

[0034] Epoxy adhesives exhibit high structural strength and high temperature resistance, making them particularly suitable as bonding adhesives.

[0035] The properties, features, and advantages of this invention described above, as well as the manner in which they are achieved, will become clearer and more readily understandable in connection with the following description of exemplary embodiments, which are explained in more detail in conjunction with the drawings. These drawings show: FIG 1 a sectional view of an exemplary embodiment of a sheet metal stack arrangement, FIG 2 a perspective view of a sheet metal stack and insulating elements arranged on it, FIG 3 a top view of a sheet metal stack and insulating elements arranged on it, FIG 4 A side view of a section of two sheet metal stacks and an insulating element arranged between the sheet metal stacks.

[0036] Corresponding parts are marked with the same reference symbols in the figures.

[0037] Figure 1 (FIG 1Figure 1 shows a sectional view of an embodiment of a laminated core assembly 1. The laminated core assembly 1 comprises several laminated cores 3, 5 arranged one above the other in a stack-like manner. Each pair of adjacent laminated cores 3, 5 is spaced apart by a number of electrically insulating elements 7, 9 arranged between them, each of which has a first contact surface 11 on one of the laminated cores 3, 5 and a second contact surface 13 on the other of the laminated cores 3, 5. A bottom laminated core 5 and an uppermost laminated core 6 are plate-like, for example, cuboid-shaped. The other laminated cores 3 are cylindrical-shaped, see Figure 1. Figures 2 and 3 Each insulating element 7, 9 is cylindrical in shape, see the Figures 2 and 3, wherein all insulating elements 7 arranged between two lamination stacks 3 have the same first height h1 and the insulating elements 9 arranged on the lowest lamination stack 5 and under the uppermost lamination stack 6 have a second height h2 which is smaller than the first height h1.

[0038] The Figures 2 and 3 The figure shows a sheet metal stack 3 and insulating elements 7 arranged on it as a partial view within a sheet metal stack arrangement. Figure 2 (FIG 2 ) a perspective view of the sheet metal stack 3 and the insulating elements 7 arranged on it and Figure 3 (FIG 3 ) shows a top view of the sheet metal stack 3 and the insulating elements 7 arranged on it.

[0039] Figure 4 (FIG 4 Figure 1 shows a side view of a section of two sheet metal stacks 3 and an insulating element 7 arranged between the sheet metal stacks 3.

[0040] The insulating element 7 has a base body 15 made of a ceramic material. The base body 15 is cylindrical with base surfaces, each having a hot-melt adhesive coating 17 made of a hot-melt adhesive. Each hot-melt adhesive coating 17 has a surface facing a lamination stack 3 and forming a contact surface 11, 13 of the insulating element 7.

[0041] The hot melt adhesive coating 17 is applied to the base body 15, for example, by means of a spraying process, dipping, roller coating, hand squeegees or brushes.

[0042] Each contact surface 11, 13 is bonded to the sheet metal stack 3 to which it rests by a bonding adhesive 19, which connects the contact surface 11, 13 and the sheet metal stack 3.

[0043] The hot melt adhesive assumes a solid state at the operating temperatures of the lamination stack arrangement 1. For example, the hot melt adhesive has a melting temperature of at least 130°C. Furthermore, the melting temperature of the hot melt adhesive is lower than the service temperature of the bonding adhesive 19.

[0044] The hot melt adhesive coating 17 has a thickness in the range of 1 µm to 2 mm, preferably in the range of 1 µm to 50 µm.

[0045] For example, the bonding adhesive 19 is an epoxy adhesive. Furthermore, the hot melt adhesive and the bonding adhesive 19 exhibit comparable strengths.

[0046] The bonding adhesive 19 is applied, for example, at room temperature to a sheet metal package 3, 5 or an insulating element 7, 9, pressed and allowed to cure.

[0047] The insulating elements 9 differ from the insulating elements 7 only in the height of the base body 15, but in particular also each have hot melt adhesive coatings 17, wherein in the case of an insulating element 9 arranged on the lowest lamination stack 5, one hot melt adhesive coating 17 is bonded to the lowest lamination stack 5 by the bonding adhesive 19 and the other hot melt adhesive coating 17 is bonded to the lamination stack 3 arranged above it by the bonding adhesive 19, and in the case of an insulating element 9 arranged below the uppermost lamination stack 6, one hot melt adhesive coating 17 is bonded to the uppermost lamination stack 6 by the bonding adhesive 19 and the other hot melt adhesive coating 17 is bonded to the lamination stack 3 arranged below it by the bonding adhesive 19.

[0048] Although the invention has been further illustrated and described in detail by means of preferred embodiments, the invention is not limited by the disclosed examples and other variations can be derived from them by the person skilled in the art without leaving the scope of protection of the invention.

Claims

1. Laminated stack arrangement (1) comprising several laminated stacks (3, 5) arranged one above the other, wherein each pair of adjacent laminated stacks (3, 5) is spaced apart by a number of electrically insulating elements (7, 9) arranged between them, each of which has a first contact surface (11) against one of the laminated stacks (3, 5) and a second contact surface (13) against the other of the laminated stacks (3, 5), wherein each contact surface (11, 13) of each insulating element (7, 9) is a surface of a hot melt adhesive coating (17) of the insulating element (7, 9) made of a hot melt adhesive and is bonded to the laminated stack (3, 5) to which it is bonded by a bonding adhesive (19) which connects the contact surface (11, 13) and the laminated stack (3, 5).

2. Sheet metal stack arrangement (1) according to claim 1, wherein each insulating element (7, 9) has a base body (15) made of a ceramic material, the surfaces of which facing the sheet metal stacks (3, 5) are each coated with the hot melt adhesive.

3. Sheet metal stack arrangement (1) according to claim 1 or 2, wherein the hot melt adhesive assumes a solid state of matter at operating temperatures of the sheet metal stack arrangement (1).

4. Sheet metal stack arrangement (1) according to one of the preceding claims, wherein the hot melt adhesive has a melting temperature of at least 130°C.

5. Sheet metal stack arrangement (1) according to one of the preceding claims, wherein a melting temperature of the hot melt adhesive is less than an upper service temperature of the bonding adhesive (19).

6. Sheet metal stack arrangement (1) according to one of the preceding claims, wherein each insulating element (7, 9) is designed as a circular cylinder, the base surfaces of which are the contact surfaces (11, 13) of the insulating element (7, 9).

7. Sheet metal stack arrangement (1) according to one of the preceding claims, wherein the hot melt adhesive and the bonding adhesive (19) have similar strengths at an operating temperature of the sheet metal stack arrangement (1).

8. Laminated stack arrangement (1) according to one of the preceding claims, wherein the hot melt adhesive has a strength of at least 2.7 N / mm² at an operating temperature of the laminated stack arrangement (1). 2 exhibits.

9. Sheet metal stack arrangement (1) according to one of the preceding claims, wherein each hot melt adhesive coating (17) has a thickness in the range of 1 µm to 2 mm, preferably in the range of 1 µm to 50 µm.

10. Laminated stack arrangement (1) according to one of the preceding claims, wherein the laminated stacks (3, 5), possibly with the exception of a bottom laminated stack (5) and / or a top laminated stack (6), are formed in a circular cylindrical shape.

11. Sheet metal stack arrangement (1) according to one of the preceding claims, wherein the bonding adhesive (19) is an epoxy adhesive.

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