Method for laminating a core part

Abstract

In one embodiment, the method is for laminating a core part (20) of a static electric induction device (1) and comprises: A) providing a first stack (41) of sheets (25) for the core part (20), B) assembling a second stack (42) of the sheets (25), the sheets (25) are taken one by one from the first stack (41), the sheets (25) are oriented between 30° and 70° relative to a vertical direction (V), C) forming a third stack (43) by taking the whole second stack (42), the sheets (25) are oriented at most 25° relative to the vertical direction (V), and D) taking the third stack (43) and incorporating it into the core part (20), the sheets (25) are oriented at most 5° relative to the vertical direction (V) in the core part (20), so that the core part (20) is laminated of the sheets (25).

Description

[0001] P2024, 1006 WO N / P240152WO01 November 12, 2025

[0002] 1

[0003] Description

[0004] Method for laminating a core part

[0005] A method for laminating a core part is provided.

[0006] Document US 2004 / 0083599 Al refers to a transformer.

[0007] Documents US 2003 / 0005570 Al, US 2021 / 0134512 Al and US 2023 / 0207181 Al also refer to transformers.

[0008] Document WO 2022 / 225201 Al relates to an apparatus and a method for supplying a top yoke - laminated core of a transformer, the apparatus and the method automating, by means of a machine device using electrical power, silicon steel plate delivery conventionally performed by people, during top yoke lamination work in a transformer manufacturing process, so that silicon steel plates can be automatically delivered without workers. The apparatus for supplying a top yoke - laminated core of a transformer, according to the present invention, may comprise: a holder having one side on which one or more silicon steel plates are placed; a support frame for supporting the one or more silicon steel plates laminated within the edge thereof; one or more lifters for lifting one silicon steel plate from among the one or more silicon steel plates; a moving guide for moving the lifter left and right; and an electric rotary plate which is provided at the top of the other side of the holder and which downwardly lowers the one silicon steel plate spaced apart from the lifter.

[0009] A problem to be solved is to provide a method to efficiently assemble a core part of a static electric induction device. P2024, 1006 WO N / P240152WO01 November 12, 2025

[0010] This object is achieved, inter alia, by a method as defined in the independent claims. Exemplary further developments constitute the subject-matter of the dependent claims.

[0011] For example, in the method described herein two robots are used to assemble an upper yoke of a transformer. A first robot takes single sheets and puts them onto a first rack, and a second robot puts a plurality of the sheets from the first rack and puts them to a second rack. The sheets are then taken manually from the second rack and placed at a final position within the upper yoke.

[0012] With this method, a physical workload can be reduced and work ergonomics can also be improved. Further, health and safety can be enhanced. Especially, physical workload reduces and ergonomics improves when robots bring core sheets in an almost vertical position as close as possible to a final upper yoke assembly location. However, core sheets may be stacked manually by operators to a final sheet location.

[0013] Upper yoke sheets are to be positioned very tightly on a core leg. Core sheet material tolerances and sheet cutting manufacturing tolerances allows relatively big variations so that final stacking of core sheets by using robots is very challenging at present, because of a lack of accuracy / precision of a reasonably costly robot.

[0014] The process described herein nearly removes manual moving and lifting of core sheets in a horizontal direction. The probability of occurrence of cut wounds is thus reduces. When core sheets are almost vertically positioned by the robots, operators lifting distances of the sheets are also reduced. P2024, 1006 WO N / P240152WO01 November 12, 2025

[0015] This gives the possibility to adjust a working height in a way that physical load for especially for the shoulders is reduced. Moreover, a shortened time to achieve the top yoke assembly process is possible. This is especially valuable to shorten a through put time and coping with larger order backlog and higher manufacturing volumes. Thus, the method described herein can contribute to increasing production capacity and shorter delivery times.

[0016] For example, half of a top yoke stack from a cutting line is brought to its location at a workstation. Also active transformer parts, like windings, are transferred to their location. Operators give an input how many sheets they need for a second support rack. Then a first robot picks one core sheet at a time from the top yoke sheet stack. The first robot enables bending of core sheets during sheet transfer, for example. Moving of sheets can be done also without bending. Longitudinal bending can be done in two direction and diagonally, from corner to corner, for example. This work phase is repeated until a desired number of sheets is transferred to the first support rack. When the desired amount of sheets is in the first support rack 1, a second robot picks up the whole stack and waits for operators command to transfer the stack to a second support rack. The first robot can already start to build up the stack for the first support rack at the stage when the second robot is waiting for the command to move the previous stack to the second support rack. This process enables a faster transfer of the sheets than using only one robot. Two robots further support that the first robot is picking only one sheet while the second robot picks multiple sheets at a time. Moreover, two robots are more flexible for different sheet sizes and allow smaller robots to be used. P2024, 1006 WO N / P240152WO01 November 12, 2025

[0017] The afore -mentioned method steps are repeated until the whole top yoke, for example, has been assembled.

[0018] For example, the first support rack is built for better alignment of the core sheets. A material of the first support rack can be wood, plastic or metal, for example. Material compatibility with regard to the core sheets shall be taken into account.

[0019] The core sheets are arranged at an angle of about 45° relative to the vertical in the first support rack number. Alignment of the core sheets is done by using a triangle support, for example. The alignment of the core sheets can also be done by using adjustable stoppers or triangle supports at the ends of the first support rack. Also pin holes in the core sheets can be used for alignment.

[0020] Also a material of the second support rack can be wood, plastic or metal. The material compatibility shall again be considered. In the second rack, the core sheets are almost in a vertical position. The second support rack can be attached to a conveyor which is able to move upwards and downwards. This enables usage of a workstation for different sizes of the active transformer parts. The second support rack can be moved up when the active transformer parts are transferred to an assembly slot. When the active transformer parts are on their correct location, the second support rack can be lowered to almost touching winding tables, for example.

[0021] According to at least one embodiment, the method is for laminating a core part. The core part is of a static electric induction device. For example, the static electric induction P2024, 1006 WO N / P240152WO01 November 12, 2025

[0022] 5

[0023] device is a transformer or electric reactor. By way of example, the electric induction device is one of the following: a 2 - leg transformer or reactor; a 3 - leg transformer or reactor, upper yoke core sheets in one piece; a 3 - leg transformer or reactor, upper yoke core sheets divided to 2 or more pieces; a 5 - leg transformer or reactor, upper yoke core sheets in one piece; a 5 - leg transformer or reactor, upper yoke core sheets divided to 2 or more pieces. The static electric induction device is, for example, of the core- type with electric windings on outmost legs or of the shell - type with outmost legs being free of electric windings, or a hybrid transformer core.

[0024] According to at least one embodiment, the static electric induction device has a mating of at least 50 kVA and of at most 315 kVA. Otherwise, the static electric induction device may have a mating of more than 315 kVA and of at most 2.5 MVA. It is further possible that the static electric induction device has a mating of more than 2.5 MVA.

[0025] According to at least one embodiment, the method comprises the step of providing a first stack of sheets for the core part. The first stack is, for example, as obtained from a cutting line or as obtained from a manufacturer.

[0026] The sheets, also referred to as core sheets or laminae or the like, may be of soft iron. It is possible that the sheets are provided with an electrically insulating coating or layer on their main sides.

[0027] According to at least one embodiment, the method comprises the step of assembling a second stack of the sheets. The sheets are taken in small numbers from the first stack. For P2024, 1006 WO N / P240152WO01 November 12, 2025

[0028] example, the sheets are taken one by one. Otherwise, two or three of the sheets may be taken.

[0029] According to at least one embodiment, in the second stack the sheets are oriented with an angle of at least 20° or of at least 30° or of at least 36° relative to a vertical direction. The vertical direction is in parallel to the vector of gravitational force. Alternatively or additionally, said angle is at most 75° or is at most 70° or is at most 60° or is at most 52°. For example, said angle is 45° ± 5°.

[0030] According to at least one embodiment, the method comprises the step of forming a third stack by taking a part of the second stack or the whole second stack. A number of sheets taken from the second step is larger than a number of sheets taken to form the second stack. For example, the number of sheets taken from the first stack is at least two or is at least four or is at least six. Alternatively or additionally, said number is at most 30 or is at most 20 or is at most twelve.

[0031] According to at least one embodiment, in the third stack the sheets are oriented with an angle of at most 35° or of at most 25° or of at most 17° or of at most 12° relative to the vertical direction. Alternatively or additionally, said angle is 0° or is more than 0° or is at least 2° or is at least 4° or is at least 6°. For example, said angle is 15° ± 5°. Said angle is more than 0° to avoid tipping of the third stack. Thus, the third stack may be self - supporting.

[0032] Especially, the sheets in the third stack are more vertical than the sheets in the second stack, and the sheets in the second stack are more vertical than the sheets in the first P2024, 1006 WO N / P240152WO01 November 12, 2025

[0033] stack. For example, the angular difference relative to the vertical direction from stack to stack is at least 30° and / or at most 45°. Said angular difference between the third stack and the second stack may be smaller than between the second stack and the first stack.

[0034] According to at least one embodiment, the method comprises the step of taking the third stack in part or as a whole and incorporating it into the core part. Thus, the third stack is used to build up the core part. Especially, the previous steps are repeated various times so that the core part is assembled by and laminated of a plurality of the third stacks and, thus, also of the second stacks. However, one first stack may be sufficient.

[0035] According to at least one embodiment, in the core part the sheets are oriented with an angle of at most 10° or of at most 5° or of at most 2° or of 0° relative to the vertical direction.

[0036] In at least one embodiment, the method is for laminating a core part of a static electric induction device, like a transformer. The method comprises the following steps:

[0037] A) providing a first stack of sheets for the core part, B) assembling a second stack of the sheets, the sheets are taken one by one from the first stack, the sheets are oriented with an angle between 30° and 70° relative to a vertical direction,

[0038] C) forming a third stack by taking the whole second stack, the sheets are oriented with an angle of at most 25 ° relative to the vertical direction, and

[0039] D) taking the third stack and incorporating it into the core part, the sheets are oriented with an angle of at most 5° P2024, 1006 WO N / P240152WO01 November 12, 2025

[0040] relative to the vertical direction in the core part, so that the core part is laminated of the sheets.

[0041] For example, the stated method steps could be performed in the stated order. However, in particular method steps B) and C) may be done simultaneously or partially simultaneously. Moreover, during method step D) it is possible that method step B) is also done simultaneously or partially simultaneously.

[0042] According to at least one embodiment, the method step B) is done by a first robot.

[0043] According to at least one embodiment, the method step C) is done by a second robot. The second robot is different from the first robot.

[0044] Otherwise, both method steps B) and C) may be done by the same robot.

[0045] According to at least one embodiment, during the method steps B) to D) the to -be - assembled core part is located between the second stack and the third stack. This may apply in top view of the core part. ' Top view' may refer to a view in parallel with the vertical direction. That is, possibly in a horizontal plane the to -be - assembled core part is between the second and third stacks.

[0046] According to at least one embodiment, the method steps B) to D) are repeated multiple times until the core part is fully assembled. Thus, as stated above. The core part may be assembled from a plurality of the third stacks. For example, the number of the third stacks used is at least 20 or is at P2024, 1006 WO N / P240152WO01 November 12, 2025

[0047] least 100 or is at least 500. Alternatively or additionally, said number is at most 6 x 103or is at most 1.5 x 103, for example.

[0048] According to at least one embodiment, between two repetitions of the method steps B) to D) the to -be - assembled core part is rotated by at least 150° and by at most 210° around a vertical axis which is in parallel with the vertical direction. Especially, said angle can be 180° ± 5°. Said step is done only once, for example, after half of the core part has been assembled. Thus, a first half of the core part may be assembled from a first side and a second half of the core part may be assembled from a second, opposite side.

[0049] According to at least one embodiment, in the second stack and / or in the third stack the sheets are bent. By having the sheets bent, a mechanical stability of the respective stack can be increased. In the core part the sheets are preferably not bent but are arranged in a plane manner.

[0050] According to at least one embodiment, a bending in the second stack and / or in the third stack is at most 10% or is at most 5% or is at most 1% of an extent of the sheets along a curvature of the sheets. Thus, the sheets may be bent weakly. For example, if a length of the sheets along the curvature is 200 mm, in case of a 1% bending the sheets are bent by 2 mm out of a plane.

[0051] According to at least one embodiment, the sheets have lateral faces. The lateral faces connect the two main sides with each other. For example, the lateral faces are produced by sawing, laser radiation and / or punching. P2024, 1006 WO N / P240152WO01 November 12, 2025

[0052] According to at least one embodiment, in the second stack and in the third stack the same lateral faces are most upward along the vertical direction. In other words, it is possible that the sheets are not rotated along a horizontal axis but are just moved without being turned around. Thus, there is no upside-down movement.

[0053] According to at least one embodiment, the third stack comprises at least two and at most twelve of the sheets when the method step D) is carried out. The third stack may include all the sheets of the second stack. The number of the sheets in steps C) and D) can thus be the same.

[0054] According to at least one embodiment, the second stack is assembled at a first rack. For example, the first rack provides an inclined plane against which the sheets are leaned. Be the inclined plane, the angle of the sheets relative to the vertical direction can be defined. It is possible that the first rack includes means for adjusting the sheets in a lateral direction, like a protrusion, pins or a stop.

[0055] According to at least one embodiment, the third stack is placed at a different, second rack. As the first rack, also the second rack may provide an inclined plane against which the sheets are leaned, and said inclined plane could define the angle of the sheets relative to the vertical direction. It is again possible that the second rack includes means for adjusting the sheets in a lateral direction, like a protrusion, pins or a stop.

[0056] According to at least one embodiment, during the method step D) a distance between the to -be - assembled core part and the P2024, 1006 WO N / P240152W001 November 12, 2025

[0057] second rack is at most 0.5 m or is at most 0.3 m or is at most 0.2 m. Thus, the to -be - assembled core part and the second rack are quite close so that just a small movement of the sheets is needed from the second rack to their final position within the core part. Especially, a height difference of the lower faces of the sheets between the final position and the third stack is at most 0.3 m or at most 0.1 m or at most 0.03 m. Thus, no or virtually no vertical distance is to be bridged between the second rack and the to-be-assembled core part.

[0058] According to at least one embodiment, the completely assembled core part is an upper yoke of a transformer core or of an electric reactor core, like a current limiting reactor core. Otherwise, the core part may be a lower yoke or even a leg of the transformer core of the reactor core.

[0059] According to at least one embodiment, seen in top view onto the main sides, an area content of some or of all the sheets is at least 0.08 m2or is at least 0.2 m2or is at least 0.4 m2. Alternatively or additionally, said area content is at most 3 m2or is at most 2 m2or is at most 1.2 m2.

[0060] According to at least one embodiment, a thickness of the sheets is at least 0.1 mm and is at most 0.6 mm or is at least 0.2 mm and is at most 0.4 mm.

[0061] According to at least one embodiment, seen in cross - section, the completely assembled core part has a round top face. For example, the completely assembled core part is of round shape, seen in cross - section and averaged over the sheets. P2024, 1006 WO N / P240152W001 November 12, 2025

[0062] 12

[0063] According to at least one embodiment, in the first stack the sheets are oriented with an angle of at least 75° or of at least 85° or of 90° relative to the vertical direction. That is, in the first stack the sheets are positioned horizontally or approximately horizontally.

[0064] According to at least one embodiment, the method step D) is done manually. For example, said method step is carried out by two workers. Otherwise, the method step D) may be carried out by a third robot different from the first and second robots or may also be carried out by the second robot.

[0065] A method for laminating a core part described herein is explained in greater detail below by way of exemplary embodiments with reference to the drawings. Elements which are the same in the individual figures are indicated with the same reference numerals. The relationships between the elements are not shown to scale, however, but rather individual elements may be shown exaggeratedly large to assist in understanding.

[0066] In the figures:

[0067] Figure 1 is a schematic block diagram of an exemplary embodiment of a method for laminating a core part described herein,

[0068] Figure 2 is a schematic side view of an exemplary embodiment of a method for laminating a core part described herein,

[0069] Figure 3 is a schematic front view of a static electric induction device the method described herein can be used for, P2024, 1006 WO N / P240152W001 November 12, 2025

[0070] 13

[0071] Figure 4 is a schematic top view of an exemplary embodiment of a sheet for a method described herein,

[0072] Figure 5 is a schematic side view of an exemplary embodiment of half of a core part for a method described herein,

[0073] Figures 6 and 7 are schematic perspective views of exemplary embodiments of racks for a method described herein,

[0074] Figures 8 to 11 are schematic perspective views of method steps of an exemplary embodiment of a method described herein,

[0075] Figure 12 is a schematic top view of an exemplary embodiment of a gripper for a method described herein, and

[0076] Figures 13 and 14 are schematic sectional views of exemplary embodiments of grippers for a method described herein.

[0077] Figure 1 illustrates an example of a method for laminating a core part 20 of a static electric induction device 1. In method step SI, a first stack 41 of sheets 25 for the core part 20 is provided.

[0078] Then, in method step S2, a second stack 42 of the sheets 25 is assembled, the sheets 25 are taken one by one from the first stack 41. The sheets 25 are oriented with an angle between 30° and 70° relative to a vertical direction V in the second stack 42.

[0079] In method step S3, a third stack 43 is formed by taking the whole second stack 42. The sheets 25 are oriented with an P2024, 1006 WO N / P240152W001 November 12, 2025

[0080] - 14 -

[0081] angle of at most 25° relative to the vertical direction V in the third stack 43.

[0082] In method step S4, the third stack 43 is taken and is incorporated it into the core part 20. In the core part 20, the sheets 25 are oriented with an angle of at most 5° relative to the vertical direction V.

[0083] The method steps S2 to S4 can be repeated various times to assemble the whole core part 20 by lamination. In this regard, the method steps S2 to S4 may partially be done simultaneously, that is, these method steps do not need to be performed temporarily one after the other.

[0084] Optionally, in method step S5 the core part is turned around a vertical axis A by 180°. This is done especially after half of the core part 20 is assembled.

[0085] In Figure 2, the geometric set-up of the method is shown in more detail. First, the sheets 25 are provided at a storage rack 53 in a first stack 41. It is possible that the first stack 41 comprises all required sheets 25 or that the first stack 41 is refilled at least once during assembly of the core part 20. In the first stack 41, the sheets 25 are stored horizontally, for example.

[0086] By a first robot 31, the sheets 25 are taken from the first stack 41 and are put onto a first rack 51. For example, the sheets 25 are taken one-by-one or otherwise in small numbers, like at most four or at most two of the sheets 25. For example, an overall number of a finished second stack 42 built by the first robot 31 is at most 15 or is at most 10 or is at most eight. In the second stack 42, the sheets are P2024, 1006 WO N / P240152W001 November 12, 2025

[0087] 15

[0088] stored at about 45° relative to a vertical direction V. As for the storage rack 53 it is possible for the first rack 51 to be adjustable in height.

[0089] By a second robot 32, part or all of the second stack 42 is transferred to a second rack 52. Thus, a number of the sheets 25 in a third stack 43 at the second rack 52 could be the same as the number of the sheets 25 in the finished second stack 42. Accordingly, the third stack 43 may be formed by just once taking sheets 25 from the first rack 51. Otherwise, in principle the third stack 43 could also be formed by taking the sheets 25 multiple times from the first rack 51.

[0090] At the second rack 52, the sheets 25 are positioned more vertical than at the first rack 51. For example, an angle of the sheets 25 in the third stack 43 relative to the vertical direction V is at most 20°. Said angle may be larger than 0° or may be at most 5° to prevent the sheets 25 from falling from the second rack 52.

[0091] Then, the third stack 43 is shifted to its final place in the core part 20. This may be done manually by an operator or by a further robot, not shown in Figure 2. From the second rack 52 to their final position, the sheets 25 may not need to be moved vertically and may be quite close to the core part 20. For example, a horizontal distance H between the second rack 52 and the core part 20 is at most 0.5 m. The distance H may be between an edge of the third stack 43 closest to the core part 20 and a central axis A of the core part 20 when being fully assembled, for example. The central axis A may be the axis of rotation in method step S5, compare Figure 1. P2024, 1006 WO N / P240152W001 November 12, 2025

[0092] - 16 -

[0093] If done by an operator, not shown, the transfer from the second rack 52 to the final position may be done from a conveyor or a working platform 54. The second rack 52 may be located between the working platform 54 and the core part 20. Correspondingly, the first rack 51 may be between the core part 20 and the storage rack 53. Also the second rack 52 and / or the working platform 54 can be adjustable in their height.

[0094] Otherwise, the same as to Figure 1 may also apply to Figure 2, and vice versa.

[0095] In Figure 3, an example of the static electric induction device 1 is shown. For example, the static electric induction device 1 is a transformer having the core 2. As illustrated in the example of Figure 3, the transformer is a 4 - leg shell -type transformer having two windings 6 at inner ones of legs 22 of the core 2. The legs 22 are based on a bottom yoke 21 and are connected at a top face 26 by means of an upper yoke 23.

[0096] For example, the core part 20 of Figure 2 corresponds to the upper yoke 23 of Figure 3. However, the bottom yoke 21 or also at least one of the legs 22 may be assembled by laminating the sheets 25 in the same manner as illustrated in connection with Figure 2, for example.

[0097] Otherwise, the same as to Figures 1 and 2 may also apply to Figure 3, and vice versa.

[0098] In Figure 4, an example of a sheet 25 is shown. The sheet 25 may be a plate of iron, like silicon steel. Not shown, the sheets 25 may carry an electric insulation at least at main P2024, 1006 WO N / P240152W001 November 12, 2025

[0099] sides 29 to reduce Eddy currents in the core 2. The main sides 29 are connected by lateral faces 28.

[0100] For example, a thickness of the sheets 25 is around 0.2 mm to 0.3 mm. By way of example, an average length L of the sheets 25 and, thus, of the core part 20 is at least 0.5 m and / or is at most 4 m. A width W of the sheets 25 is, for example, at least 0.05 m and / or at most 0.8 m. Especially the width W may vary significantly within the core part 20 as the overall core part 20 may be of round shape, compare Figure 5 illustrating half of the core part 20. Within the core part 20, the sheets 25 may be arranged symmetrically with regard to a horizontal central line of the core part 20, not drawn in Figure 5.

[0101] Optionally, the sheets 25 have a cut out 24. The cut out 24 may be arranged centrally in the core part 20. It is possible that there is one cut out 24 per inner leg 22. That is, considering the core 2 of Figure 3, there would be two of the cut outs 24. Alternatively or additionally, there can be bevels 37 at ends of the sheet 25. These bevels 37 may correspond to outer legs 22 of the overall core 2. For example, an angle of the bevels 37 and / or of edges of the cut out 24 is 45 °.

[0102] Otherwise, the same as to Figures 1 to 3 may also apply to Figures 4 and 5, and vice versa.

[0103] In Figures 6 and 7, the first and second racks 51, 52 are drawn in more detail.

[0104] For example, seen in side view, the racks 51, 52 are of triangular basic structure. An angle of the sheets 25 in the P2024, 1006 WO N / P240152W001 November 12, 2025

[0105] 18

[0106] stacks 42, 43 is defined by an inclined plane 55 of the racks 51, 52. The racks 51, 52 and especially the inclined planes 55 and other parts coming into contact with the sheets 25 may be of a material being compatible with the sheets 25, especially may be made of a non-magnetic material. To avoid scratches, the inclined planes 55 may be made of a relatively soft and cost - efficient material like wood or plastics.

[0107] Optionally, see Figure 6, the first rack 51 comprises an adjustment structure 56. When being placed onto the first rack 51, the sheets 25 are self - adj us ted by the adj ustment structure 56. The adjustment structure 56 may correspond to the cut out 24, for example. Alternatively or additionally, such adjustment structures could be present for the bevels 37. Other than shown, such at least one adjustment structure could also be present at the second rack 52.

[0108] Optionally, see Figure 7, the second rack 52 comprises a protrusion 50. The sheets 25 may rest on the protrusion 50. It is possible that the protrusion 50 is perpendicular to the inclined plane 55. A length of the protrusion 50 is preferably as small as possible and corresponds, for example, to the number of sheets 25 to be received by the second rack 52 plus a security margin. It is possible that the length of the protrusion 50 is adjustable to account for diff erent numbers of the sheets 25 to be handled.

[0109] Otherwise, the same as to Figures 1 to 5 may also apply to Figures 6 and 7, and vice versa.

[0110] In Figures 8 to 11, another example of the method is illustrated. In this method, the robots 31, 32 and the to-be-assembled core part 20 are located in a security box 36 to P2024, 1006 WO N / P240152W001 November 12, 2025

[0111] - 19 -

[0112] protect operators 7 from being accidentally injured by the robots 31, 32 and moving sheets 25. The robots 31, 32 may be placed at separate pedestals 35 or other than shown on a same pedestal. The at least one pedestal 35 may be adjustable in height to be in an optimal position relative to the core part 20 depending on a size of the core 2. Also the racks 51, 52, 53 and the working platform 54 may be adjustable in height.

[0113] In the step of Figure 8, the first robot 31 picks one of the sheets 25 from the first stack 41. This is done, for example, by a vacuum gripper 33. As can be seen in Figure 9, the first robot 31 puts the previously picked sheet 25 onto the first rack 51. The steps of Figures 8 and 9 are repeated until the desired number of sheets 25 is on the first rack 51 so that the second stack 42 is built. By doing so, the sheets 25 are positioned more vertically. As the adjustment structure 56 can be used, the sheets 25 can precisely be position on the first rack 51.

[0114] The first robot 31 may comprise a two - fold arm and the gripper 33. Optionally, the gripper 33 may be fixed relative to the robot arm. The robot arm may be of fixed length or may have an adjustable length. However, during assembling the second stack 42 the robot 31 preferably makes short movements without turns around a horizontal axis and without length adj us tments.

[0115] In Figure 10 it is shown that the second robot 32 picks the whole second stack 42 and puts it onto the second rack 52. This is done, for example, by a magnetic gripper 34. As shown in Figure 11, the whole second stack 42 is put onto the second rack 52 so that the third stack 43 arises. P2024, 1006 WO N / P240152W001 November 12, 2025

[0116] In doing so, the sheets 25 may be lifted across the to-be-assembled core part 20 and also across the first rack 51 to reach the second rack 52. In the second rack 52, the sheets 25 are arranged relatively vertically, for example, at an angle of 16° relative to the vertical direction V.

[0117] As the first robot 31, the second robot 32 may also have a two - fold arm. During moving the sheets 25 onto the second rack 52, the arm of the second robot 32 may perform a movement around a vertical axis.

[0118] Optionally, not shown in Figures 8 to 11, the second robot 32 may have a waiting position. In the waiting position it is possible that the gripper 34 holds the third stack. For example, the waiting position is atop the second rack 52. Further optionally, the first robot 31 may build a further second stack 42 on the first rack 51 during movement of the second robot 32 and / or during the second robot 32 is in its waiting position.

[0119] The waiting position may be hold until the operators 7 have moved the sheets of the previous third stack 43 to their final position in the core part 20. Movement of the second robot 32 may be initiated by the operators 7 for safety reasons manually, for example.

[0120] Otherwise, the same as to Figures 1 to 7 may also apply to Figures 8 to 11, and vice versa.

[0121] In Figures 12 to 14, an example of the grippers 33, 34 is illustrated in more detail. The grippers 33, 34 may comprise a base bar 57 at which a plurality of holding units 58 is placed. The holding units 58 may be vacuum units or P2024, 1006 WO N / P240152W001 November 12, 2025

[0122] electromagnets, for example. The base bar 57 can be of straight fashion. Depending on a size of the sheet 25, not all of the holding units 58 need to be engaged, compare Figure 12 in which differently sized sheets 25 are indicated.

[0123] In Figure 13 it is shown that the gripper 33, 34 further comprises a bending head 59. The bending head 59 may be located underneath the base bar 57. On both sides of the base bar 57 and, thus, of the bending head 59 there can be one of the holding units 58. Thus, by the triplet of said two holding units 58 and the bending head 59 a well-defined bending can be introduced in the at least one sheet 25 of the respective stack 42, 43. The bending of Figure 13 may be referred to as convex.

[0124] Said triplet may be aligned perpendicular to a length direction of the at least one sheet 25, for example. In the grippe 33, 34 of Figure 12, there are two of such triplets.

[0125] Otherwise, the same as to Figures 1 to 11 may also apply to Figures 12 and 13, and vice versa.

[0126] In Figure 14 it is illustrated that the triplets are formed of only one holding unit 58 but of two of the bending heads 59, the holding unit 58 being between the bending heads 59. One of the bending heads 59 may be underneath the base bar 57. The bending of Figure 14 may be referred to as concave.

[0127] A deflection B introduced by the at least bending head 59 of Figures 13 or 14 is, for example, at least 1 mm and at most 20 mm, for example, around 2 mm. P2024, 1006 WO N / P240152W001 November 12, 2025

[0128] 22

[0129] The deflection B as shown in Figures 13 and 14 is along the width direction W, compare Figure 4. However, the deflection B may alternatively be along the length direction L or may also be diagonally, that is, from corner to opposite corner of the respective at least one sheet 25, seen in top view. The bending stiffens the at least one sheet 25 during sheet movements done by the first robot 31 and / or by the second robot 32.

[0130] Otherwise, the same as to Figure 13 may also apply to Figure 14, and vice versa.

[0131] The invention described here is not restricted by the description on the basis of the exemplary embodiments.

[0132] Rather, the invention encompasses any new feature and also any combination of features, which includes in particular any combination of features in the patent claims, even if this feature or this combination itself is not explicitly specified in the patent claims or exemplary embodiments.

[0133] This patent application claims the priority of European patent application 2421 3619.0, the disclosure content of which is hereby incorporated by reference. P2024, 1006 WO N / P240152W001 November 12, 2025

[0134] - 23 -

[0135] List of Reference Signs

[0136] 1 static electric induction device

[0137] 2 core of the static electric induction device 20 core part

[0138] 21 bottom yoke

[0139] 22 leg

[0140] 23 upper yoke

[0141] 24 cut out

[0142] 25 sheet

[0143] 26 top face of the core part

[0144] 27 bottom face of the core part

[0145] 28 lateral face

[0146] 29 main side

[0147] 31 first robot

[0148] 32 second robot

[0149] 33 vacuum gripper

[0150] 34 magnetic gripper

[0151] 35 pedestal

[0152] 36 security box

[0153] 37 bevel

[0154] 41 first stack

[0155] 42 second stack

[0156] 43 third stack

[0157] 50 protrusion

[0158] 51 first rack

[0159] 52 second rack

[0160] 53 storage rack

[0161] 54 working platform

[0162] 55 inclined plane

[0163] 56 adjustment structure

[0164] 57 base bar

[0165] 58 holding unit P2024, 1006 WO N / P240152W001 November 12, 2025

[0166] - 24 -

[0167] 59 bending head

[0168] 6 winding

[0169] 7 operator

[0170] A vertical axis of rotation

[0171] B deflection

[0172] H distance between the core part and the second rack L average length of the sheets

[0173] S method step

[0174] V vertical direction

[0175] W width of the sheets

Claims

P2024, 1006 WO N / P240152W001 November 12, 2025Patent Claims1. A method for laminating a core part (20) of a static electric induction device (1) comprising:A) providing a first stack (41) of sheets (25) for the core part (20),B) assembling a second stack (42) of the sheets (25 ), the sheets (25) are taken one by one from the first stack (41), the sheets (25) are oriented with an angle between 30° and 70° relative to a vertical direction (V),C) forming a third stack (43 ) by taking the whole second stack (42), the sheets (25) are oriented with an angle of at most 25° relative to the vertical direction (V), andD) taking the third stack (43 ) and incorporating it into the core part (20), the sheets (25) are oriented with an angle of at most 5° relative to the vertical direction (V) in the core part (20), so that the core part (20) is laminated of the sheets (25 ).

2. The method according to the preceding claim,wherein the method steps B) and C) are done by at least one robot (31, 32 ).

3. The method according to the preceding claim,wherein the method step B) is done by a first robot (31) and the method step C) is done by a different, second robot (32).

4. The method according to any one of the preceding claims, wherein the method step D) is done manually.

5. The method according to any one of the preceding claims, wherein during the method steps B) to D) the core part (20) is located between the second stack (42) and the third stackP2024, 1006 WO N / P240152W001 November 12, 2025(43 ), seen in top view of the core part (V) in parallel with the vertical direction (V).

6. The method according to any one of the preceding claims, wherein the method steps B) to D) are repeated multiple times until the core part (20) is fully assembled.

7. The method according to any one of the preceding claims, wherein between two repetitions of the method steps B) to D) the core part (20) is rotated by at least 150° and by at most 210° around a vertical axis (A) which is in parallel with the vertical direction.

8. The method according to any one of the preceding claims, wherein in at least one of the second stack (42) or the third stack (43 ) the sheets (25) are bent,wherein a deflection (B) is at most 10% of an extent of the sheets (25) along a curvature of the sheets (25).

9. The method according to any one of the preceding claims, wherein the sheets (25) have lateral faces (28),wherein in the second stack (42) and in the third stack (43 ) the same lateral faces (28) are most upward along the vertical direction (V).

10. The method according to any one of the preceding claims, wherein the third stack (43 ) comprises at least two and at most twelve of the sheets (25) when the method step D) is carried out.

11. The method according to any one of the preceding claims, wherein the second stack (42) is assembled at a first rack (51) and the third stack (43 ) is placed at a different,P2024, 1006 WO N / P240152W001 November 12, 2025second rack (52),wherein during the method step D) a distance (H) between the core part (20) and the second rack (52) is at most 0.5 m.

12. The method according to any one of the preceding claims, wherein the completely assembled core part (20) is an upper yoke (23 ) of a transformer core (2).

13. The method according to any one of the preceding claims, wherein the sheets (25) comprise iron,wherein in the core part (20) the sheets (25) are electrically insulated from one another,wherein, seen in cross - section, the completely assembled core part (20) has a round top face (26).

14. The method according to any one of the preceding claims, wherein, seen in top view, an area content of at least some of the sheets (25) is at least 0.08 m2and is at most 2 m2, wherein a thickness of the sheets (25) is at least 0.2 mm and is at most 0.4 mm.

15. The method according to any one of the preceding claims, wherein in the first stack (41) the sheets (25) are oriented with an angle of at least 75° relative to the vertical direction (V).

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