EP1016105B1 - Method and device for producing bundles of sheet metal laminates for magnetic cores - Google Patents

Description

The invention relates to a method for the production of interconnected laminations consisting of packages for magnetic cores, so-called laminated cores.

At one of the EP-B 0 133 858 Known methods for producing such laminated cores are punched out of a strip of slats and provided on one side with depressions and on the other side with matching with the wells and opposite them surveys. These elevations are pressed in the form of at least two circular warts during assembly of each package in the wells. In this case, cylindrical holes are punched in a lamella per laminated core, which serves as a separation lamella, instead of the depressions. In these cylindrical holes, the warts of the adjacent lamella engage.

Laminations of this type are used, inter alia, in various electromagnetic apparatus, such. As reactors, transformers, actuators, actuators such. B. solenoid valves, etc.

The applications of laminated cores in magnetic circuits has been state of the art for many years and serves to reduce eddy currents, the z. B. in transformers to increase the losses or contribute to solenoid valves to extend the switching times. As an alternative to laminated cores, ring-belt cores are used, but they have the disadvantage that the coils needed for the control have to be pushed before closing the magnetic circuit.

By specifying a rectangular iron cross-section in laminated cores, the use of laminated cores in various cases could not be optimized so far. In many applications, it is desirable to keep the recesses for the laminated cores to be inserted round or oval.

If a laminated core with a rectangular iron cross-section is then introduced into such a round or oval recess, the comparatively low iron cross-section is disadvantageous with respect to the diameter of the recess. This disadvantage is particularly serious when the Einsatzgegebenheiten require miniaturization of the components, as is necessary in particular in internal combustion engines.

Although they are out JP-A-09 213 543 and EP-A-0 738 831 Methods are known in which sheet packages with round or oval iron cross section become available, but due to the assembly of the magnetic core of two or more packages of previously assembled lamellae, these methods are cumbersome.

It is therefore an object of the present invention to further develop the said production processes in such a way that even laminated cores having a round or oval iron cross-section become available in a simpler manner.

This is achieved by a method according to claim 1 according to the invention.

The device according to the invention for carrying out the method is characterized by the features of claim 10.

Particular embodiments are defined in the dependent claims.

The invention will be explained in more detail below with reference to the drawing, for example.

In the prior art, in a follower tool having a plurality of work stations, fins A are punched out of a punching tape and stacked to form packages. According to the state of the art, identical lamellae A in the follower tool are provided on one side with depressions B and on the other side with warts C which correspond to the depressions B and are opposite them. When assembling each package at least two circular warts C is pressed into the corresponding recesses B. Each package is a lamella, which serves as a separation blade A ', instead of recesses provided with cylindrical holes D. In these holes D then enter the warts C of the adjacent slats. This is shown schematically in FIG. FIG. 2 shows a separation lamella A 'in cross-section.

As can be seen from FIGS. 3 and 4, according to the present invention, no longer identical lamellae are punched out in the same progressive die, but the sheet widths are varied after the introduction of the warts. About the control of the progressive tool after each punching step, the width of the punched laminations are adjusted by lateral displacement of the cutting punch. In the exemplary embodiment shown in FIG. 3, a narrow lamella whose width makes up approximately 30% of the desired diameter of the package is punched out first. This narrow lamella serves as separation lamella 1 and has two cylindrical holes D. The two cylindrical holes are punched in the middle and their diameter accounts for about 10% of the package diameter. In these cylindrical holes warts of the adjacent blade 2 are pressed. Before the next punching stroke of the tool, the cutting punches are moved by motor to the width of the next sheet. This next lamella 2 has approximately 50% of the width of the coil core. In this lamella 2 are introduced in the same follower tool on one side with depressions and on the other side with the wells B matching and opposite them warts C. As a result, then the slats are knotted 3 to 11 with increasing width analog.

For the now following lamellae 10 'to 1', the lateral cutting punches are then brought together successively again, so that the package shown in FIG. 3 and FIG. 4 can be removed as a finished part from the progressive die tool.

In this way it is possible, e.g. To produce a cylindrical coil core for a round ignition coil, which fills a high proportion of the cross-sectional area of the circle.

In the following Table 1, embodiments are described in which a bar core with a diameter of 30 mm was made from lamellae of different thickness according to the method according to the invention. In this case, the iron cross section has been measured in comparison to a laminated core with a rectangular iron cross section. Table 1: Strip thickness [mm] Iron cross section round laminated core (%) Iron cross section right laminated core (%) 1.5 93 63 1.0 95 64 0.7 97 64 0.5 98 64 0.3 99 64

With the inventive method cylindrical coil cores were made of 0.5 mm thick grain-oriented iron silicon, which varied in diameter from 5 mm to 20 mm.

FIG. 5 shows an EK core 20 with a rectangular iron cross-section according to the prior art. Such EK cores are used in actuators for diesel injectors. The task here was to produce an EK core, which can be screwed into a limited volume of construction and can achieve a high level of force. The EK core 20 shown in FIG. 5 has only insufficient results, since the area utilization of the round outer contour 21 for the iron cross section is only 31%.

The round EK core 30 shown in FIG. 6 was adapted to the round outer contour 31 using the method according to the invention. The design of the follow-on composite tool was carried out as for the production of the cylindrical coil cores shown in Figures 3 and 4 by moving the cutting punch. The round EK core 30 of the following invention shown in FIG. 6 has a significantly higher area utilization in comparison to the EK core 20 from FIG. Thereby a 20% higher area utilization was achieved.

The laminations were again made of iron silicon and compared with prior art laminations. In the actuator for a diesel fuel injection valve, an increase in the magnetic circuit force level of 20% was achieved.

FIG. 7 shows an EK core 40 according to the present invention with a breakthrough on the middle leg, like the one shown in FIG DE-U 2951 4508 can be seen. For the middle slats 41, 42 a recess 43 is provided to the center, so that in the application a central guide for a valve rod (not shown) is made possible. Also in this application, the force level could be increased by 19% compared to a comparable laminated core with a rectangular iron cross section. The EK core 40 shown again consists of grain-oriented iron silicon.

In the optimization of the EK core 40 shown in FIG. 7 with outwardly rounded contours, the limitation on the utilization of the circular area is determined by the width of the outer sheet metal layers. A further optimization according to the invention can take place in that the required for the production of cores inner cutting punch the follow-on composite tool are moved by a motor. As a result, the center leg of the laminated core is rounded and thus created sufficient space for the outer layers so that a punching technical link in the tool is still possible.

FIG. 8 shows a laminated core 50 adapted to the round shape, in which a 44% larger iron cross-sectional area is achieved in comparison with the laminated core from FIG. 6 with a rectangular iron cross-section.

A corresponding laminated core 50 in an installation space of 20 mm made of lamellae of 1 mm thick iron silicon scored in comparison to a laminated core 40 with rectangular iron cross section a force of 78 N instead of 54 N.

Claims (17)

1. A process for the production of packages composed of linked sheet laminae for magnet cores in which laminae (1-11, 1'-10') are punched out from a strip and are provided on one side with indentations (B) and on the other side with elevations lying opposite the indentations (B) and corresponding to them, where the elevations, in the form of at least two projections (C), are pressed into the indentations (B) during assembly of each package, whereby with one lamina per package serving as a separating lamina (A'), instead of depressions (B), holes (D) are punched, into which the projections of the adjacent lamina engage,
   characterised in that
   out of the strip, laminae (1-11, 1'-10') are punched that have a varying width and that are linked to one another into a package that at least partially has an almost round iron cross-section, and
   that first, the separating lamina (A') is punched out,
   that after each punch step, the widths of the punched-out sheet laminae (1-11,1'-10') of a package are readjusted,
   that the projections of the adjacent lamina (2) are pressed into the holes (D) of the separating lamina (A'), and
   that, subsequently, the laminae (3-11) with increasing width are linked.
2. A process according to claim 1,
   characterised in that
   during the assembly, the elevations in the form of at least two circular projections (C) are pressed into the indentations (B) in each package, whereby with one lamina per package, which serves as a separating lamina (A'), instead of the indentations cylindrical holes (D) are punched, into which the projections of the adjacent lamina engage.
3. A process according to claim 1 or 2,
   characterised in that
   E-shaped lamina are punched out from the strip, whose outer branches and/or centre branch have varying widths.
4. A process according to one of claims 1 through 3,
   characterised in that
   the indentations (B) and the projections (C) of each lamina (1-11, 1'-10') are continuously stamped using a punch under the simultaneous counterforce effect of counterpunches, whereby the diameter of the projections is formed larger than the diameter of the corresponding indentation (B) and the height of the projections is formed smaller than the depth of the corresponding indentation (B), which attains at least 50% of the thickness of the lamina.
5. A process according to claim 5,
   characterised in that
   the indentations (B) and the projections (C) are continuously stamped by the punch for at most 10 ms longer, after the counterpunches have reached their final position.
6. A process according to claim 4, characterised in that
   the diameter of the projections is formed at most 20 µm larger than the diameter of the corresponding indentation (B), and the height of the projections is formed at most 0.1 mm less than the depth of the corresponding indentation (B).
7. A process according to claim 4,
   characterised in that
   the laminae (1-11, 1'-10') are prestamped or prepunched at the target locations of the indentation and the projections.
8. A process according to one of the preceding claims,
   characterised in that
   the package that has at least partially an almost round iron cross-section, can be removed as a finished part from the progressive tool.
9. A device according to one of the preceding claims,
   characterised in that
   the separating lamina (A') is punched out with a width of approximately 30% of the target diameter of the package.
10. A device to implement the process according to claim 1, composed of a progressive tool with laterally movable cutting punches.
11. A device according to claim 10,
    composed of a progressive tool with patrix and matrix dies and several workstations,
    characterised in that
    in the stamping station for the indentations (B) and the projections, at least two stamps are provided, and two counterstamps, which are adjustable in height in the die, that each counter stamp is provided with a connection at the base of the matrix die to determine its final location and that in the stamp-out station of the finished lamellae (1-11,1'-10'), brake elements are installed underneath the matrix die, which run transverse to the axes of the counterpunches and which provide necessary resistance during the connection of the individual finished laminae (1-11,1'-10') below one another.
12. A device according to claim 10 or claim 11,
    characterised in that
    after each punching step, the width of the punched-out sheet laminae of a package is readjusted by a lateral sliding of the cutting punch.
13. A device according to claim 12,
    characterised in that
    the width of the punched-out sheet laminae is readjusted using the control of the progressive tool.
14. Use of a package of linked sheet laminae (1-11, 1'-10') produced with the process according to one of claims 1 through 9, as a magnet core in a solenoid valve.
15. Use of a package of linked sheet laminae (1-11, 1'-10') produced with a process according to one of claims 1 through 9 as a magnet core in a servo drive.
16. Use of a package of linked sheet laminae (1-11, 1'-10') produced with a process according to one of claims 1 through 9 as a magnet core in a transformer.
17. Use of a package out of linked sheet laminae (1-11, 1'-10') produced with a process according to one of claims 1 through 9 as a magnet core in an activator.

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