EP0251993A1 - Method of and device for assembling lamination packets, particularly for transformer cores - Google Patents

Abstract

Positioning of the individual portions is no longer effected on the laminating station but on a positioning station which is arranged upstream of the laminating station. In the positioning station the individual portions of a layer are deposited and positioned by being pushed against each other. The finally positioned individual layer is then delivered as a closed unit to the laminating station and laminated to form a transformer core. The individual portions are stacked on a stacking station in such a way that they are already arranged in the correct relative position with respect to each other.

Description

The invention relates to a method according to the preamble of claim 1 and to an apparatus for performing the method according to the preamble of claim 9.

With a few exceptions, the layered cores for distribution and power transformers with outputs of more than 30 KVA are still layered by hand. Mechanical stops and pre-oriented stacks, which are provided around the shift station, serve as assembly aids. A worker shifts approx. 6 to 30 sheets per minute, depending on the size of the sheets and the available assembly equipment.

Fully and semi-automatic systems have already been built for layering the cores. For example, cut individual sections are distributed on conveyor belts and fed to the shift station. Some of the sections fed in parallel must be turned and struck 90 ° using a rotating device. The disadvantage of these systems is that they are relatively complicated and very expensive. To convert to other sheet metal dimensions, time-consuming retrofitting work is required so that the system has long downtimes. In addition, in most cases it is necessary to drill the sheets for centering during layering, which has a disadvantageous effect on the finished transformer core.

It is therefore an object of the invention to provide a method and a device of the type mentioned at the beginning with which a fully automatic layering of sheet metal cores is possible with minimal effort and great efficiency. Tolerance fluctuations in the external dimensions of the sheets should not have a negative effect, i.e. do not lead to air gaps at the joints, which would result in electrical losses of the transformer. The process should also be carried out without mechanical changes to the sheets, i.e. without centering holes or the like.

This object is achieved according to the invention with a method with the features according to claim 1 or with an apparatus with the features according to claim 9. The actual positioning and striking of the individual sections of a layer takes place on a separate positioning station and not on the layer station on the already partially layered layer body. No measures are therefore required on the laminate itself to prevent the individual sections from slipping, since only individual layers that have already been positioned and struck are deposited on the laminate station.

A further rationalization effect is achieved if the individual sections on a stacking station are already provided in stacks in the correct relative position to one another and if each individual section of a layer is transported together from the stacking station to the positioning station. In this way, all individual sections of a layer can be fed to the positioning station with a single movement, which allows the use of a gripper system. Obviously, this is much easier than feeding with conveyor belts, roller conveyors or robot systems.

A single layer can be positioned particularly easily on the positioning station if an individual section is fixed in a predetermined position or aligned on a predetermined axis and if all other individual sections of a layer are positioned by pushing, the fixed or aligned individual section being the position of all pushed individual sections determined. This means that no holes are required to position the individual sections. Length tolerances of the individual sections are automatically compensated for, since the individual sections are always pushed against each other up to the stop. This reliably prevents air gaps at the joints. In this way, three-phase transformers with three parallel legs and two yokes can be layered particularly advantageously by first aligning the middle leg on a predetermined axis at the positioning station and then pushing the two yokes and the two outer legs. The butt joints can be blunt, mortised or bevelled.

Since at least one yoke has to be removed again after layering in order to apply the bobbins to the parallel legs, a teaching yoke can also be provided at the positioning station, which yoke always remains at the positioning station and only serves to align the remaining individual sections. A layer that is open on one side is thus transported from the positioning station to the layer station and piled up to form a core that is open on one side.

Individual sections are preferably pushed into their end position with an axially symmetrical movement on the positioning station and measured in this position with a measuring system. In this way, missing or incorrectly dimensioned sheets or those with the wrong position be determined. Automatic creation of a measurement protocol is also possible, so that the nature of the layered core can be checked on the basis of measurement data.

The individual layers are transported from the stacking station to the positioning station, preferably with a movable gripper, which bends the ends of the individual sections when they are lifted off the stack. In this way, the relatively strong adhesive force can be overcome when lifting the individual sheets from the stack. Moving lifting from the stacking station does not have a disadvantage since the individual sections do not have to be placed in an exact position on the positioning station. On the other hand, the completely positioned layer is transported from the positioning station to the layer station with a rigid gripper, which guarantees an exactly plane-parallel transport without moving the butt joints. A plane-parallel lifting without the occurrence of adhesive forces from the positioning station is made possible in that the positioning station has a support table with a structured surface.

Positioning on the positioning station is particularly easy to implement if it has a support table with grooves and if the push-on device consists of push-on elements which protrude from the support table through the grooves and are displaceable in the grooves. In this arrangement, the push-on device is arranged essentially under the support table, so that there are no disruptive machine elements next to or above the positioning station. Two interacting push-on elements are preferably attached to a parallel running rope, so that an axially symmetrical movement of the push-on elements relative to or away from one another is possible.

The positioning station preferably has a hold-down device with which the bent-up ends of the individual sections can be held down when the individual sections are pushed. This reliably prevents any bent ends of individual sections from lying on top of one another when pushed. The hold-down device is advantageously integrated directly into the gripper between the positioning station and the shift station.

A particularly high degree of automation can be achieved if four grippers are attached at an angle of 90 ° to each other on a rotating unit that can be rotated about a vertical central axis, and if two positioning stations and each are offset around the central axis by 90 ° a stacking station and a shift station are arranged, the two positioning stations being diametrically opposite one another. The transport from the stacking station via the positioning station to the shift station takes place in a constant reciprocal reciprocating movement, a shift always being fed and positioned on a positioning station and being lifted off again at the next but one cycle and being transported further. Every single pendulum movement therefore fulfills a function. A further optimization of the production can be achieved if different stacking tables can optionally be fed in at the stacking station. In this way, the prepared stacks can be automatically fed to the various stages of a core cross-section on different tables. This makes it possible to produce multi-stage cores practically fully automatically without downtimes for retrofitting etc.

• Figur 1 eine schematische Darstellung des Arbeitsablaufs beim Schichten,
• Figur 2 eine Draufsicht auf den Kern eines mehrstufigen Dreiphasen-Transformators,
• Figur 3 einen Querschnitt durch die Linie I-I des Kerns gemäss Figur 2,
• Figur 4 eine Draufsicht auf eine Einzelschicht mit ver­setzten Stossstellen,
• Figur 5 eine Draufsicht auf eine an die Schicht gemäss Figur 4 anschliessende Schicht mit wechselseitig versetzten Stössen,
• Figur 6 den Positioniervorgang einer Schicht gemäss den Figuren 4 und 5,
• Figur 7 den Positioniervorgang für eine einseitig offene Schicht mit Lehrjoch,
• Figur 8 einen Querschnitt durch einen Auflagetisch mit darunter angeordneter Anschiebevorrichtung,
• Figur 9 eine stark vereinfachte Draufsicht auf die Vor­richtung gemäss Figur 8,
• Figur 10 eine stark vereinfachte Draufsicht auf eine Anschiebevorrichtung zum Positionieren einer Schicht gemäss Figur 6,
• Figur 11 das Abheben eines Einzelabschnitts von der Stapel­station mit einem beweglichen Greifer in vier Stadien,
• Figur 12 einen Querschnitt durch Greifvorrichtung und Auf­lagetisch in zwei Stadien,
• Figur 13 einen Querschnitt durch eine Niederhaltevorrich­tung mit verbogenen Einzelabschnitten,
• Figur 14 eine alternative Ausgestaltung einer Niederhalte­vorrichtung,
• Figur 15 eine Seitenansicht auf eine Schichtvorrichtung mit pendelnder Dreheinheit,
• Figur 16 eine Draufsicht auf die Vorrichtung gemäss Figur 15,
• Figuren 17 bis 19 die virschiedenen Arbeitstakte der Vorrichtung gemäss den Figuren 15 und 16.

Embodiments of the invention are shown in the drawings and are described in more detail below. Show it:

• FIG. 1 shows a schematic representation of the workflow during layering,
• FIG. 2 shows a top view of the core of a multi-stage three-phase transformer,
• FIG. 3 shows a cross section through line II of the core according to FIG. 2,
• FIG. 4 shows a plan view of a single layer with offset joints,
• FIG. 5 shows a top view of a layer adjoining the layer according to FIG. 4 with mutually offset joints,
• 6 shows the positioning process of a layer according to FIGS. 4 and 5,
• FIG. 7 shows the positioning process for a layer open on one side with a yoke,
• FIG. 8 shows a cross section through a support table with a pushing device arranged underneath,
• FIG. 9 shows a greatly simplified top view of the device according to FIG. 8,
• FIG. 10 shows a greatly simplified top view of a push-on device for positioning a layer according to FIG. 6,
• FIG. 11 the lifting of a single section from the stacking station with a movable gripper in four stages,
• FIG. 12 shows a cross section through the gripping device and support table in two stages,
• FIG. 13 shows a cross section through a hold-down device with bent individual sections,
• FIG. 14 shows an alternative embodiment of a hold-down device,
• FIG. 15 shows a side view of a layer device with an oscillating rotating unit,
• FIG. 16 shows a plan view of the device according to FIG. 15,
• FIGS. 17 to 19 show the different work cycles of the device according to FIGS. 15 and 16.

As shown in FIG. 1, the various individual sections 3 are first provided in stacks on a stacking station 5. The stacks are already in the correct position relative to each other, but are not absolutely exactly aligned. The individual sections 3 of a layer are lifted together from the stacking station and placed on the positioning station 4. As indicated by dot-dash lines, these individual sections have the same relative position to one another after being deposited as on the stacking station 5. The individual sections of the layer on the positioning station are then pushed against one another until the layer forms a self-contained structure. In this case, an individual section, for example a middle leg, is preferably fixed or at least aligned on a specific axis, while all the remaining individual sections are pushed on. The fully positioned individual layer is then closed by the positioning station 4 transported to the shift station 2 and deposited there exactly, or stacked to form a layer body 1. Lateral moments of force no longer act on the already layered individual layers, since the individual sections no longer have to be positioned. The exact placement of the positioned individual layers on the shift station can be achieved with simple means.

The method is particularly advantageous for the layering of transformer cores, especially three-phase transformers. Of course, other laminates can also be built in the same way as they are used in construction or mechanical engineering. Various configurations are also conceivable for the configuration of the transformer cores. For example, a multi-stage core of a three-phase transformer can be layered, as shown in FIGS. 2 and 3. Of course, single-phase transformers of the core or jacket type or even more complicated five-leg transformers can also be produced. The core cross sections can obviously also be modified as desired. Depending on the application, core cross sections can also be realized with cooling slots. The butt joints of the individual sections can be blunt or mortised, the ends of the individual sections being cut at right angles or at an angle.

FIGS. 2 and 3 show, for example, a typical core 6 of a three-phase transformer with a stepped cross section, which is composed of the middle leg 12, the two outer legs 13 and the two yokes 14. The ends of the individual sections are cut at an angle of 45 °. The cross section of the core is five-stage and is composed of the first and fifth stages 7 and 11, the second and fourth stages 8 and 10 and the middle and third stages 9.

FIGS. 4 and 5 show the arrangement of the individual sections of two successive layers in more detail. In order to keep the magnetic losses within the core as small as possible, the individual successive layers are stacked offset from one another. In the case of the three-legged core, this is done in the simplest way by the fact that the middle leg 12 has a leg tip 19 which is arranged offset by the dimension a from the central axis 20. The yokes 14 are provided with a V-cut 15, which is arranged in the middle of a yoke. When the yokes 14 are pushed onto the middle leg 12 with the offset leg tips 19, the simplest way is that the joints of the yokes with the outer legs 13 also have an offset. FIG. 4 shows a layer with the upper yoke offset to the left relative to the central axis 20. In the next layer according to FIG. 5, the middle leg 12 is arranged in the opposite direction, so that the tip 19 of the leg is offset by the dimension a to the right of the central axis 20. This accordingly results in an upper yoke 14 shifted to the right. A core consists of shifted layers according to FIGS. 4 and 5. This mutual construction of the core is known per se and is no longer explicitly mentioned in the explanations below.

Figure 6 shows the processes involved in positioning a layer for a three-legged core. The positioning is carried out with push elements 21 which are displaceable in grooves 22. In FIG. 6a the individual sections have their basic position, which corresponds to the position on the stacking station 5 mentioned above. In a first step, the middle leg 12 is aligned and held on the axis of symmetry Y with the aid of the push-on elements 21, as shown in FIG. 6b. However, the middle leg can move freely in the Y-axis, which may be due to rolling elements on the shank elements is made easier. In a next step according to FIG. 6c, the two yokes 14 are pushed with an axially symmetrical movement relative to the axis of symmetry X and with a certain force against the middle leg 12 up to the stop. The layer is now aligned with both the Y and X axes. Finally, in a last step according to FIG. 6d, the outer legs 13 are also individually struck against the yokes 14 with a parallel movement relative to the axis of symmetry Y. Tolerance fluctuations in the length of the various individual sections are automatically compensated for, so that gap-free joints occur. The layer which has been positioned in this way is then fed to the layer station for layering the core using a suitable device.

FIG. 7 shows the process for positioning a layer for the production of a core that is open on one side. A teaching yoke 17 is arranged on the positioning station, which takes on the function of the second yoke. In the yoke 17, the push-on elements 21 engage in longitudinal slots 23, so that a lateral movement of the yoke relative to the axis of symmetry Y is possible. As FIG. 7a shows, the individual sections are first placed back on the positioning station. The middle leg 12 is then aligned and held in the Y-axis, as shown in FIG. 7b. According to FIG. 7c, the teaching yoke 17 is then first moved into position. Depending on whether the tip of the middle leg is shifted to the left or to the right, the teaching yoke in the slots 23 can move to the left or to the right. In the next step according to FIG. 7d, the yoke 14 is pushed onto the middle leg 12 parallel to the X axis with a certain force. At the end, the two outer legs 13 are again pushed in parallel, as shown in FIG. 7e. When the positioned shift is lifted off, the yoke obviously remains on the positioning station, so that a core open on one side is stacked on the layer station.

The structure and mode of operation of a push-on device are described in more detail below with reference to FIGS. As already briefly mentioned, the positioning station 4 has a support table 24 which is provided with grooves 22 in which the push-on elements 21 projecting beyond the table can be displaced. FIG. 8 shows a cross section through a single groove with an individual section 3 lying on the support table 24. The individual push-on elements 21 are pivotally mounted on an axis 26, which in turn is fastened to a push-on carriage 25. The push-on elements 21 are prestressed in the push-on direction with a spring 31 and can be adjusted with a stop screw 27. The push-on carriages 25 are fastened to a parallel running rope 28 and move on rollers 30 on a linear guide 29.

As shown in FIG. 9 in particular, the parallel running rope 28 is tensioned by means of deflection rollers 33. A push-on carriage 25 and 25auf is attached to each stretched section of the parallel running rope. When the parallel running cable 28 is driven in one direction of rotation, the two push-on carriages 25 and 25ʹ obviously move towards or away from each other. This achieves an axially symmetrical movement which is used to push the sheet metal sections.

The parallel rope 28 is driven by a drive rope 36 which is tensioned parallel to the parallel rope 28. This drive cable 36 is driven via a drive wheel 37 by a motor, not shown, at a constant speed. The connection between the drive cable 36 and parallel running cable 28 is established via a driver 34, which is connected to the parallel by means of a cable clamp 35 Running rope 28 is attached. The driver 34 is resiliently mounted relative to the drive cable in that a spring 40 is arranged between the cable clamp 63 on the drive cable 36 and the driver 34. The drive cable 36 is guided through a bore 64 on the driver 34. The spring 40 can be preloaded with the rope clamp 65. With the cable clamp 63 fixed to the drive cable 36 is a cam 38 with which a switch 39 on the driver 34 can be activated. When pushing the sheet metal sections on the support table 24, the driver 34 pulls the parallel running rope 28 in the direction of arrow A, so that the two push-on carriages 25 and 25ʹ move towards one another. As soon as the section 3 has been brought into position and can no longer be moved on the support table 24, the pushing carriages 25 and 25ʹ are braked by tensioning the springs 31 on the pushing elements 21. As soon as the parallel running rope has been brought to a standstill as a result, the driver 34 moves relative to the drive rope 36, which continues to run. The spring 40, which has a smaller spring constant than the springs 31, is pressed together until the cam 38 actuates the switch 39. This brings the drive wheel 37 to a standstill.

In the pushed-on position of the push-on elements 21, a measuring device 32 is preferably actuated, as is indicated schematically in FIG. 9. It can be an incremental or an absolute measuring system. The position of the push-on elements 21 is determined with the measuring system and passed on to a control device. The control device compares the determined values, for example the width of the middle leg and the position of the yoke and side leg pushers with predetermined values and triggers an interference signal if there are deviations between the actual dimension and the target dimension.

For the opening of the push-on elements, the drive wheel 37 is reversed until the push-on carriages 25 and 25ʹ have reached an opening position determined by the measuring system 32. The drive wheel 37 is then stopped and the positioning station is ready for a further pushing operation.

FIG. 10 shows the combination of several parallel running ropes, as is required, for example, for the push-on process shown in FIG. 6. With 41 and 41ʹ the two cables for pushing the outer legs are shown. The only difference from the parallel running rope shown in FIG. 9 is that the two push-on elements 21 do not move parallel, but diagonally towards one another, but parallel to the X axis. The drive with the aid of a drive cable is otherwise exactly the same, but is not shown in Figure 10 for reasons of clarity. The push elements 21 of the cables 41 move in the direction of arrow B.

Position 42 shows the cable pull for the middle leg. Here, two push-on elements 21 are fastened in pairs on a push-up carriage 25 via the axis 26 and move in pairs towards or away from each other in the direction of arrow C.

The cable pull 43 for pushing the yokes is constructed in the same way as the cable pull 42, but arranged at 90 ° to it. The push-on elements 21 of the cable pull 43 move in the direction of the arrow D. Of course, the individual cable pulls are arranged under the support table 24 in such a way that they do not interfere with one another. Depending on the number of individual sections to be positioned, additional cables with parallel running cables could be arranged under the support table. Of course, however, the push-on elements 21 could also be actuated in other ways be done, such as with counter-rotating spindles, with pneumatic cylinders or similar drive elements.

Figures 11 and 12 relate to the gripper device. As shown in FIG. 11, a movable suction gripper 44 is used to lift the individual sheets from the stacking station 5, in which the ends of each sheet are bent open when they are lifted off. The gripper has a plurality of resiliently mounted gripper arms 46 and at least one bellows 45 for each individual section. The gripper arms 46 and the bellows 45 are connected via a line 66 to a vacuum source. The gripping arms 46 are provided on the underside with suction heads 49, while the bellows has a suction lip, not shown. FIG. 11a shows the position of the gripper immediately before being placed on the stack at the stacking station 5. When lowering onto the stack, all suction heads 49 and the bellows 45 are pressed onto the uppermost section, as shown in FIG. 11b. As soon as a vacuum is built up via line 66, suction heads 49 and bellows 45 suck in a single section 3. The bellows 45 is contracted so that it lifts one end of the sheet. As a result, the adhesive forces on the sheet metal are overcome and air can flow under the bent sheet metal section. Figure 11c shows the beginning of the lifting process. FIG. 11d shows that the individual sections 3 are transported from the stacking station 5 to the positioning station 4 not in a plane-parallel manner but rather in a slightly bent manner. However, this does no further harm, since the individual sections do not have to be placed exactly on the positioning station.

In order to prevent the bent ends of individual sections from being pushed one above the other when pushing on the positioning station, a hold-down device 50 is preferably used, as shown in FIG. The hold-down device 50 is preferably in the Integrated gripping device. It has the effect that the possibly bent ends of the individual sections 3 are held down in such a way that they cannot be pushed over one another when pushed onto the support table 24. As FIG. 14 shows, spacer pins 51 can be used, each of which ensures a minimal air gap between the flat individual sections 3 and the underside of the holding-down device 50.

FIG. 12 shows a gripping device with a rigid gripper plate 48, as is used for the transport of a positioned layer from the positioning station 4 to the layer station 2. The support table 24 is structured by means of depressions 47, so that virtually no adhesive forces can occur when a layer is lifted off. The gripper plate itself is preferably also structured so that the layer does not stick to the gripper plate 48 when it is deposited at the shift station 2.

The gripping device with the integrated hold-down device is lowered onto the positioning station. It is positioned on and then sucked in. This ensures an absolutely precise transport to the shift station without moving the individual sections.

The overall arrangement of a layer device according to the invention is explained below with reference to FIGS. 15 to 19. On a rotating unit 52 in the form of a cross, four grippers are arranged offset from one another by 90 °. This is a first sheet gripper 60, a second sheet gripper 61 and a first layer gripper 58 and a second layer gripper 59. The rotating unit 52 is mounted on a center column 53 and can be rotated about it. A stacking station 5, two positioning stations 4 and 4ʹ and a shift station 2 are arranged around the center column 53, likewise offset by 90 ° to one another. The two posi toning stations 4 and 4ʹ are arranged diametrically opposite one another. Various stacking tables 62 and 62ʹ can optionally be fed to the stacking station 5 on rails 56. The stacking tables 62 are arranged on trolleys 55. As FIG. 16 shows, the stacking table 62 is at the stacking station 5, while the stacking table 62ʹ is in the waiting position directly next to it. Individual sections of different widths can be provided on the stacking tables 62 for the different stages of a transformer core. As an alternative to the linear feeding of the stacking tables 62, it would of course also be possible to provide a turntable which feeds the correspondingly pre-stacked stacks of a certain dimension to the stacking station 5. The height of the stacking table 62 is adjustable and can be adapted to the respective stacking height.

The shift station 2 consists of a scissor table 54 which can also be moved and the height of which can be adapted to the core to be layered. After the layering process has ended, the scissor table 54 can be moved to the tilting station 57, where the layered core can be set up for further processing.

FIGS. 17 to 19 show the various automated work cycles when the core is layered on the layer station 2. In the position according to FIG. 17, a sheet layer is picked up by the stacking station 5 with the first sheet metal gripper 60. At the same time, a first positioned layer is picked up by the positioning station 4 with the first layer gripper 58. The second sheet gripper 61 places a sheet layer previously picked up at the stacking station 5 on the second positioning station 4ʹ and the second layer gripper 59 puts a ready positioned layer picked up on the positioning station 4ʹ onto the layer station 2.

For the next work cycle, the rotating unit 52 moves in the direction of the arrow E until the rotating unit has assumed the position shown in FIG. 19. The first sheet metal gripper 60 places its sheet metal layer previously picked up by the stacking station 5 on the now empty positioning station 4, while the second sheet metal gripper 61 picks up a new layer at the stacking station 5. At the same time, the first layer gripper 58 places its positioned layer picked up by the positioning station 4 on the layer station 2 and the second layer gripper 59 picks up the positioned layer from the positioning station 4ʹ. For the next work cycle, the rotating unit 52 is pivoted back in the direction of the arrow F, so that it again assumes the position shown in FIG. The process of picking up and putting down the various layers can start again. With each pendulum movement, a layer is thus transported from the stacking station to a positioning station or from a positioning station to the layer station. Of course, instead of the rotary conveying movement, a linear movement with stations arranged one behind the other would also be conceivable. The device produces an optimal rationalization effect in that the cost of layering a core is up to five times less than manual layering. The system can be operated practically fully automatically, so that an operator is only required for the preparatory work or if a fault occurs. Different yoke and leg lengths can be stacked on the system without any significant conversion work. Different nominal dimensions for the stops can be preprogrammed in a control device, so that the operator only has to select the program corresponding to the desired core configuration.

Claims (20)

1. A method for laminating laminated cores, in particular transformer cores, in which several laminated layers are layered on a layer station (2) to form a compact laminated body (1), each layer consisting of abutting individual sections (3), characterized in that the individual sections (3) of each layer are positioned on a positioning station (4), and the layers positioned in this way are fed to the layer station (2) to build up the layer body (1). 2. The method according to claim 1, characterized in that the individual sections (3) on a stacking station (5) are provided in stacks in the correct relative position to one another, and that each individual sections (3) of a layer together from the stacking station (5) on the Positioning station (4) can be transported. 3. The method according to claim 1 or 2, characterized in that on the positioning station (4) in each case a single section is fixed in a predetermined position or aligned on a predetermined axis, and that all other individual sections of a layer are positioned by pushing, the fixed or aligned individual section determines the position of all pushed individual sections. 4. The method according to claim 3 for layering a transformer core with three parallel legs and two yokes connecting the leg ends, characterized in that on the positioning station (4) first the middle leg (12) on a predetermined axis (Y) is aligned so that the yokes (14) are then pushed onto the middle leg (12) and finally the side legs (13) are pushed onto the yoke. 5. The method according to claim 3 for layering a transformer core with three parallel legs, which are open at one end and connected to a yoke at the other end, characterized in that on the positioning station (4) first the middle leg (12) on one predetermined axis is aligned that a yoke (17) at the open end of the leg and the yoke (14) are pushed onto the middle leg (12) at the closed end of the leg, and that lastly the side legs (13) onto the yoke (17) or the yoke (14) can be pushed. 6. The method according to claim 4 or 5, characterized in that the side legs (13) and / or the yokes (14) are pushed into their end position with an axially symmetrical movement. 7. The method according to any one of claims 3 to 6, characterized in that the individual sections (3) or the legs (12, 13) and yokes (14) are measured when their pushed-in end position is reached, that the determined measured values are checked by means of a control device and that when there are measured values that deviate from a nominal dimension, the control device emits an interference signal. 8. The method according to any one of claims 2 to 7, characterized in that the individual layers are transported from the stacking station (5) to the positioning station (4) with a movable gripper which bends the individual sections (3) open when they are lifted off the stacks, and / or that the layers from the positioning station (4) to the shift station (2) can be transported plane-parallel with a rigid gripper without moving the joints. 9. Device for layering laminated cores, in particular transformer cores, consisting of several sheet metal layers composed of individual sections (3) with a layer station (2) on which the sheet metal layers are stacked, characterized in that they have a positioning station (4) with a Has pushing device on which the individual sections (3) of a layer can be pushed against one another in their end position, and that the positioned individual sections of a layer can be transported and deposited together with a gripper onto the layer station (2). 10. The device according to claim 9, characterized in that it has a stacking station (5) on which the individual sections (3) can be stacked in the correct relative position to one another, and that the unpositioned individual sections (3) of a layer with a gripper from the stacking station (5) can be transported and stored on the positioning station (4). 11. The device according to claim 10, characterized in that the gripper between the stacking station (5) and the positioning station (4) is a suction gripper (44), the gripper arms (46) and at least one bellows (45) which can be contracted under vacuum for each individual section (3) ) with which a single section can be bent open when lifting. 12. Device according to one of claims 9 to 11, characterized in that the gripper between the positioning station (4) and the shift station (2) is a rigid gripper with which a layer can be lifted plane-parallel. 13. The apparatus according to claim 12, characterized in that the positioning station (4) has a support table (24) with a structured surface. 14. The device according to one of claims 9 to 13, characterized in that the positioning station (4) has a support table (24) with grooves (22), and that the push-on device consists of push-on elements (21) which through the grooves (22) protrude from the support table (24) and are displaceable in the grooves (22). 15. The apparatus according to claim 14, characterized in that two push elements are attached to a parallel running rope (28) and are axially symmetrically displaceable thereon. 16. The apparatus according to claim 15, characterized in that each parallel running rope (28) is provided with a drive device which has a switch-off device which can be activated when a force acting on a push-on element (21). 17. Device according to one of claims 13 to 16, characterized in that it has a hold-down device (50) with which the ends of the individual sections (3) can be held down on the positioning station (4) when pushing the individual sections. 18. The apparatus according to claim 17, characterized in that the holding-down device (50) is integrated in the gripper between the positioning station and the shift station. 19. Device according to one of claims 10 to 18, characterized in that four grippers (58, 59, 60, 61) offset from one another at an angle of 90 ° each A rotating unit (52) is fastened, which can be rotated about a vertical central axis, and that two positioning stations (4, 4ʹ) and one stacking station (5) and one shifting station (2) are arranged around the central axis, each offset by 90 °. wherein the two positioning stations (4, 4ʹ) are diametrically opposite each other. 20. The apparatus according to claim 19, characterized in that at the stacking station (5) different stacking tables (62, 62ʹ) can be optionally fed.

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