Device and method for demagnetizing a component

Abstract

A device (1) for demagnetizing a component (2) is proposed, comprising at least one demagnetizing coil (3, 4, 5) (3, 4, 5, 3', 4', 5') and a current source (6, 7), which are arranged and designed to interact in order to generate a magnetic field (9) in an interaction area of ​​the demagnetizing coil (3, 4, 5) (3, 4, 5, 3', 4', 5'). It is essential that the device (1) comprises at least three demagnetizing coils (3, 4, 5, 3', 4', 5') which are arranged in a common coil plane (8) each at a vertex of a polygon, and that the current source is configured to supply the demagnetizing coils (3, 4, 5, 3', 4', 5') with a periodic alternating current (I1, I2, I3, I1', I2', I3') wherein the alternating currents (I1, I2, I3, I1', I2', I3') in the demagnetizing coils (3, 4, 5, 3', 4', 5') are phase-shifted relative to each other in order to create a spatially and temporally variable magnetic field (9).

Description

[0001] The invention relates to a device and a method for demagnetizing a component.

[0002] In industrial manufacturing, components may exhibit undesirable magnetic properties even in their initial state or acquire these properties only as a result of processing during a manufacturing process. This particularly applies to components made of or containing a ferromagnetic material such as iron, nickel, or cobalt, for example, steel.

[0003] If a component is undesirably magnetic, it can, for example, exert forces on other components in an assembly or negatively influence moving electrical charges. Furthermore, the applicability of non-destructive testing methods, such as eddy current testing, can be negatively limited by the magnetic properties of the component being tested. Therefore, it is often desirable to demagnetize such a component before it is further processed industrially, assembled in an assembly, or subjected to a testing procedure such as the eddy current testing method mentioned above.

[0004] DE 10 2017 109 149 A1 discloses a device comprising a demagnetizing coil, a power source, and a control unit, which are cooperatively arranged and configured to generate a magnetic field in an interaction region of the demagnetizing coil. The magnetic field serves to demagnetize the component.

[0005] From DE 41 29 456 A1 a demagnetization device is known in which three demagnetization coils are arranged in a common plane such that the coil axes lie in the common plane.

[0006] Demagnetizing a component typically requires achieving the lowest possible level of residual magnetism within the component. However, this is complicated by the fact that magnetic components can have multiple component regions with varying magnetic properties and whose preferred magnetic directions are aligned along different spatial directions. This complicates reliable demagnetization with only one main field direction of the magnetic field, as it is often unknown whether and in which component regions different magnetic properties, in particular differently oriented preferred magnetic directions, exist.

[0007] The invention is therefore based on the object of proposing a device and a method with which a good demagnetization of a magnetic component is possible in a reliable manner.

[0008] The object is achieved by a device according to claim 1 and by a method according to claim 13. Advantageous further developments are the subject matter of the dependent subclaims.

[0009] The device according to the invention serves to demagnetize a component and comprises at least one demagnetizing coil and a current source, which are arranged and designed to cooperate in order to form a magnetic field in an interaction region of the demagnetizing coil.

[0010] The device according to the invention differs from previously known devices in that it comprises at least three demagnetizing coils, which are each arranged in a common coil plane at a corner point of a polygon, and the current source is designed to apply a periodic alternating current to the demagnetizing coils, wherein the alternating currents in the demagnetizing coils are phase-shifted with respect to one another in order to make the magnetic field variable in space and time.

[0011] According to the invention, the device and the generation of the variable magnetic field make it possible to reliably demagnetize a component. A particular advantage is that no knowledge of the component's magnetic properties is required to perform the demagnetization.

[0012] In particular, studies have shown that, due to the spatial and temporal variation of the magnetic field, differently magnetized component areas can each be exposed to an opposing field with a high probability, which allows them to be optimally demagnetized. This allows the Weiss domains of a ferromagnetic component to be aligned largely randomly, which allows particularly hard magnetic components to be reliably demagnetized.

[0013] Preferably, the spatial and temporal variation of the magnetic field can be adjusted in the manner of a so-called moving field or a traveling field, wherein a field strength and / or a field density and / or a field orientation of the magnetic field changes spatially as a function of time. Preferably, a position and / or an orientation of the magnetic field relative to at least one of the demagnetizing coils in the coil plane is variable.

[0014] A further advantage of the device according to the invention is that it features a simple electrical design. The demagnetizing coils can be any electrical coil, in particular a choke coil, whose electrical properties are preferably adjustable depending on the magnetic field to be generated.

[0015] In a simple embodiment, the demagnetizing coils each comprise an electrical wire wound with a desired winding pattern and whose ends are electrically connected, in particular switchably connected, to the power source. Preferably, the demagnetizing coils are each configured as cylindrical coils with a rectilinear coil axis. Furthermore, the invention is not limited to a coil shape, a coil cross-sectional geometry, a coil height, a number of turns, or a wire diameter. Preferably, at least one of the demagnetizing coils comprises a core configured as a laminated core or a ferrite core.

[0016] Preferably, the currents that can be applied to the demagnetizing coils are in the range between 10 amperes and 100 amperes. This distinguishes the device according to the invention particularly from those in which current-carrying electrical coils are used for non-destructive testing of components, although significantly lower currents are used and no significant demagnetization can be achieved.

[0017] The power source may comprise at least one power converter and be designed to convert a fed-in current type, i.e. a direct current or an alternating current, into the other current type and / or to change at least one characteristic parameter such as a phase position, amplitude or frequency.

[0018] In addition, the power source, particularly with a power converter, serves to supply alternating current to the demagnetizing coils of the polygon. According to the invention, the periodic alternating currents in the demagnetizing coils are phase-shifted from one another. In other words, the alternating currents in the demagnetizing coils exhibit a regularly repeating, temporal current intensity profile, for example, in the form of a time-dependent sine wave. The period durations of the alternating currents may be identical, but the times of their zero crossings differ due to the phase shift.

[0019] The power source can be designed to generate an alternating current itself and / or preferably to be connectable to another power source, for example a stationary power grid, in order to provide the alternating currents for the demagnetizing coils.

[0020] The control unit is preferably designed as an electrical control device that is at least signal-connected to the power source or integrated into it. The control unit expediently controls the power source and is designed to signal-determine the application of alternating current to the demagnetizing coils according to a control routine stored and adjustable in the control unit. The control unit can be structurally connected to the power source or separate from it. It is also within the scope of the invention for the control unit to form the power source.

[0021] According to the invention, the arrangement of the demagnetizing coils corresponds to a polygon. For this purpose, the demagnetizing coils can each have a center of area with respect to their respective coil cross-section and can be arranged such that the center of area of ​​the demagnetizing coils each form a corner point of the polygon. It is within the scope of the invention that another geometric feature of the demagnetizing coils can also serve to define the polygon. The demagnetizing coils each have a coil axis which runs through the respective center of area and is oriented such that it is orthogonal to the coil plane. It is also within the scope of the invention that the coil axes each enclose an angle between zero and ninety degrees with the coil plane. In principle, the device is not limited to a specific number of demagnetizing coils.Accordingly, the polygon can be designed as a triangle, a square, a pentagon, a hexagon, etc., whereby the number of demagnetizing coils preferably corresponds to the number of corners.

[0022] The coil plane can be viewed as an imaginary plane spanned by the vertices of the polygon. Preferably, demagnetizing coils each have a coil axis and are spaced parallel to each other with respect to the coil axes and oriented perpendicular to the coil plane.

[0023] In connection with the invention described here, the magnetic properties of the component can be expressed in at least one component property from which it can be concluded that the component is magnetic. Preferably, the magnetic property can be expressed by a physical quantity that describes the strength of a magnetic field generated by the component, in particular a magnetic field strength or a magnetic flux density. However, the invention is not limited to how the magnetic property of the component to be demagnetized manifests itself. In connection with the invention described here, a magnetic property can be used synonymously with the term "magnetization."

[0024] In an advantageous further development, the demagnetizing coils of the polygon are arranged such that the magnetic field can be formed with a plurality of field lines which run at least partially between two adjacent demagnetizing coils and substantially parallel to the coil plane.

[0025] The parallel alignment of the field lines to the coil plane allows the magnetic field to penetrate the surface area of ​​the component for demagnetization in such a way that the field lines between the adjacent demagnetizing coils also run parallel to the component surface. This enables reliable demagnetization of the component over a large area – especially compared to a magnetic field whose field lines penetrate the surface area orthogonal to the surface.

[0026] Preferably, the field lines extend substantially along an extension axis of the magnetic field, which extends at least temporarily between two adjacent demagnetizing coils in such a way that two adjacent corner points of the polygon lie on the extension axis.

[0027] In particular, the spatially variable magnetic field can consist, at least temporarily, of two subfields that can be generated by two adjacent demagnetizing coils. Preferably, the subfields can be configured such that they spatially overlap, at least temporarily, along an extension axis of the magnetic field.

[0028] In an advantageous development, the power source, particularly in cooperation with the control unit, is configured to apply alternating current to each of the demagnetizing coils in such a way that the field lines can be oriented substantially parallel to at least one side of the polygon. In particular, the field lines can be oriented parallel to each side of the polygon with a temporal offset.

[0029] By applying phase-shifted current to the demagnetizing coils, it is possible to temporarily adjust the magnetic field such that the orientation of its field lines essentially corresponds to the sides of the polygon. By appropriately aligning the demagnetizing coils, it is possible to adjust the spatial directions in which the component is to be exposed to the generated magnetic field. This is particularly beneficial for demagnetizing hard magnetic components.

[0030] In an advantageous further development, the device comprises exactly three demagnetizing coils, wherein the polygon is a triangle.

[0031] The above-described refinement is based on the realization that the advantages of the invention can be achieved with just three demagnetizing coils. In particular, by generating the spatially variable magnetic field, it is possible to orient the field lines of the magnetic field along the sides of the triangle, thereby achieving demagnetization in three different spatial directions.

[0032] According to this development, the three demagnetizing coils comprise a first demagnetizing coil, a second demagnetizing coil, and a third demagnetizing coil. A first alternating current that can be generated in the first demagnetizing coil can be set to a first phase. Accordingly, a second alternating current in the second demagnetizing coil can be set to a second phase, and a third alternating current in a third demagnetizing coil can be set to a third phase. The first phase is shifted relative to the second phase and relative to the third phase. The second phase is shifted relative to the first phase and the third phase. A phase difference between the first, second, and / or third phase can each be specified as an angle, with one full period corresponding to an angle of 360°.

[0033] The device with the three demagnetizing coils can preferably be used together with at least one other device with three or more demagnetizing coils. In particular, the demagnetizing coils of the devices can each be arranged in multiple coil planes, which are arranged parallel or at an angle to one another. This allows large-area and complexly shaped components to be permeated with a plurality of variable magnetic fields.

[0034] In an advantageous development, the power source comprises a power converter, preferably designed as a three-phase power converter. The alternating currents in at least two of the three demagnetizing coils are phase-shifted by 120° from each other.

[0035] An advantage of the development described above is that the power converter can be a commercially available three-phase power converter, which is typically also used in other applications, such as operating electrical machines. By means of a pairwise phase difference of 120°, the magnetic field can be set similar to a rotating field when the demagnetizing coils are energized, with the demagnetizing coils arranged in the triangle being continuously energized. The magnetic field that can be generated in this way extends with some of its field lines, depending on the phase positions, in the manner already described, in pairs between two adjacent demagnetizing coils and at least partially parallel to the coil plane. The alternating currents in all demagnetizing coils are preferably phase-shifted by 120° or an integer multiple thereof.

[0036] In an advantageous further development, the current source, in particular in cooperation with the control unit, is designed to set the alternating currents at a frequency between 5 Hz and 50 Hz.

[0037] Studies have shown that a frequency range of 5 Hz to 50 Hz is particularly suitable for adjusting the alternating currents, as it allows for good spatial distribution of the generated magnetic field. In particular, a good penetration depth of the magnetic field can be adjusted in the surface area of ​​common components. Furthermore, studies have shown that the generation of the magnetic field leads to forces and thus to mechanical vibrations, which must be supported by the device's bearing elements. In the frequency range of 5 Hz to 50 Hz, these mechanical vibrations and the design effort required to support them are well balanced against the achievable spatial distribution of the generated magnetic field. Another advantageous development is that the frequency can be adjusted between 5 Hz and 30 Hz.

[0038] In an advantageous development, the current source, particularly in cooperation with the control unit, is configured to continuously change the current strengths of the alternating currents from a first amplitude to a second amplitude, wherein the second amplitude is lower than the first amplitude. In particular, the reduction in the current strength between the first amplitude and the second amplitude can occur in pulses, particularly with a pulse duration of 1 second or less than 1 second.

[0039] Studies have shown that, particularly at the end of a demagnetization process, the component can become undesirably magnetized by the spatially and temporally variable magnetic field. One way to counteract this is to move the demagnetization coils away from the component in a relative motion. According to the advantageous development described above, it is also possible to reduce the current amplitudes of the alternating currents in the demagnetization coils, in particular to zero amperes, and thus also prevent the component from being undesirably magnetized. This eliminates the need for relative movement between the demagnetization coils and the component to prevent unwanted magnetization of the component.

[0040] Preferably, the current source, in cooperation with the control unit, can be configured to reduce the current intensities of the alternating currents according to a ramp function. The ramp function can have a linear progression for this purpose. Alternatively, an exponentially decreasing progression can also be provided.

[0041] Preferably, the device is designed to demagnetize the component during a relative movement relative to the demagnetizing coils. In an advantageous development, the demagnetizing coils are mounted such that demagnetization can be performed during the relative movement between the demagnetizing coils and the component along at least one movement axis.

[0042] The refinement described above is not limited to the manner in which the relative movement between the three demagnetizing coils and the component is generated. Rather, the relative movement can result from different movement components between the demagnetizing coils and the component. The movement axis is an imaginary spatial axis along which the movement between the demagnetizing coils and the component can be described.

[0043] In a first simple embodiment, the three demagnetizing coils are movably mounted, with a demagnetizing coil movement adjustable with a demagnetizing coil speed. The component can be mounted stationary. This is particularly advantageous if the component is heavy or large, making it difficult to move. If the component is flat and the coil plane is displaced relative to the surface area by means of a translational movement, the movement of the demagnetizing coils runs along the movement axis.

[0044] In a second embodiment, the three demagnetizing coils are mounted stationary. The component is mounted movably relative to the three demagnetizing coils, with component movement being adjustable at a component speed. If the component is displaced relative to the demagnetizing coils by means of a translational movement, the movement of the component runs along the movement axis. If the component is a rotationally symmetrical component with a rotation axis about which it is rotatable, the movement axis can run tangentially to the surface of the component. In particular, the component can be a rolling bearing ring or a disc-shaped component.

[0045] A third embodiment represents a combination of the first and second embodiments described above, wherein both the demagnetizing coils and the component are moved parallel to the movement axis, preferably in opposite directions.

[0046] Preferably, the relative orientation of the demagnetizing coils is adjustable depending on the relative speed relative to the component and / or on an alternating current frequency of one of the alternating currents that can be generated.

[0047] In an advantageous further development, the demagnetizing coils, in particular the three demagnetizing coils, are arranged such that during the relative movement at least a first side of the polygon in the coil plane is oriented parallel to the movement axis.

[0048] According to the above-described refinement, the field lines of the magnetic field can be aligned, at least temporarily, along the movement axis. This promotes the demagnetization of the component in a direction along the movement axis and is particularly advantageous when the alternating currents each have a frequency in the range between 5 Hz and 50 Hz, in particular 30 Hz. This is because the parallel alignment of the first side to the movement axis can increase the period during which the component can be exposed to the magnetic field along the movement axis.

[0049] In a further advantageous development, the demagnetizing coils, in particular the three demagnetizing coils, are arranged such that during the relative movement at least a second side of the polygon in the coil plane is oriented orthogonally to the movement axis.

[0050] According to the above-described development, the demagnetizing coils can be arranged such that the second side of the triangle is oriented transversely to the axis of movement of the demagnetizing coils and / or the component. In particular, this results in the field lines of the magnetic field being oriented at least temporarily transversely to the axis of movement of the demagnetizing coils and / or the component. This promotes the demagnetization of the component transversely to the axis of movement of the demagnetizing coils and / or the component.

[0051] The further development in which the second side is oriented orthogonally to the axis of movement can be provided alternatively or in addition to a further development in which the first side is oriented parallel to the axis of movement.

[0052] In a further advantageous development, the three demagnetizing coils, in particular the three demagnetizing coils, are arranged such that during the relative movement at least a third side of the polygon in the coil plane is oriented at an acute angle to the movement axis.

[0053] According to the above-described development, the three demagnetizing coils can be arranged such that the third side of the triangle is aligned at an angle between 0 and 90° to the axis of movement of the demagnetizing coils and / or the component. In particular, this results in the field lines of the magnetic field being aligned, at least temporarily, at a corresponding angle to the axis of movement of the demagnetizing coils and / or the component. This can also promote the demagnetization of the component.

[0054] The further development in which the third side is aligned at an acute angle to the axis of movement of the demagnetizing coils and / or the component can be provided alternatively or in addition to a further development in which the first side is oriented parallel to the axis of movement and / or in which the second side is oriented orthogonally to the axis of movement.

[0055] In an advantageous further development, the device comprises at least six demagnetizing coils arranged in two coil planes spaced parallel to one another. Three of the six demagnetizing coils are each arranged at a corner point of a first polygon extending in a first coil plane. Three of the other six demagnetizing coils are each arranged at a corner point of a second polygon extending in a second coil plane.

[0056] One advantage of the refinement described above is that components with comparatively large dimensions can be demagnetized by arranging them, at least in part, between the two coil planes. This is particularly advantageous when the dimensions of the component are so large that the interaction area of ​​the generated magnetic field cannot penetrate the component to the desired extent. Even with components with comparatively small dimensions, the arrangement of demagnetizing coils in two coil planes can be advantageous, for example, when a cylindrical component is only to be demagnetized superficially on its end faces, so that the demagnetizing coils can be dimensioned accordingly small with respect to the propagation of the magnetic field.

[0057] Preferably, two magnetic fields can be generated simultaneously, which can be used to demagnetize a component, thereby reducing the time required for demagnetization. In particular, rolling bearing rings or cylindrical components with large axial dimensions can be demagnetized at the front.

[0058] The two magnetic fields that can be generated can be dependent or independent of each other with regard to their spatial and temporal variability. It is within the scope of the advantageous development that the at least six demagnetizing coils can be controlled by means of a common control unit or multiple control units. Furthermore, it is within the scope of the advantageous development that the device has one or more power sources and / or can be connected to them.

[0059] According to the invention, the demagnetizing coils each have a coil axis which runs orthogonally to the coil plane.

[0060] The feature described above is particularly advantageous when the component to be demagnetized has comparatively large dimensions and the arrangement of demagnetizing coils can be brought close to this area in order to demagnetize the component. In this context, investigations by the applicants have shown that a particularly good demagnetizing effect can be achieved when the coils are directed with their respective coil axes in the direction of the component to be demagnetized. Advantageously, the device is designed to be moved relative to the component, wherein the demagnetizing coils and / or the component can be moved and, in particular, a scanning movement between the demagnetizing coils and the component is possible and, at the same time, the magnetic field is made to vary spatially and temporally.

[0061] In an advantageous further development, the demagnetizing coils each have a coil axis which runs parallel to the coil plane.

[0062] The above-described refinement is particularly advantageous when the component to be demagnetized has comparatively small dimensions and can be arranged between the demagnetizing coils, in particular, so that the coil axes point in the direction of the component to be demagnetized. A relative movement between the demagnetizing coils and the component can be realized in such a way that the component is displaced orthogonally to the coil plane and, at the same time, the magnetic field is formed in a spatially and temporally variable manner.

[0063] As mentioned above, the object is also achieved by a method for demagnetizing a component. According to the invention, demagnetization takes place by means of at least one demagnetizing coil having an interaction region in which a magnetic field is generated and the component is arranged. It is essential for the method that at least three demagnetizing coils are provided, each of which is arranged in a coil plane at a corner point of a polygon, and that the demagnetizing coils are each supplied with a periodic alternating current, wherein the alternating currents in the demagnetizing coils are phase-shifted relative to one another and the magnetic field changes spatially and temporally, and that the component is demagnetized in the interaction region by means of the magnetic field.

[0064] An advantage of the method according to the invention is that the generation of the spatially variable magnetic field enables effective demagnetization of the component. As already explained with regard to the device according to the invention, ferromagnetic components in particular can have component regions in which the preferred magnetic direction can be oriented differently. By generating the spatially and temporally variable magnetic field, this can be formed as a counterfield with a temporal offset relative to several Weiss domains during the implementation of the method according to the invention. As a result, the Weiss domains can be aligned largely randomly, whereby hard magnetic components in particular can be reliably demagnetized or a desired magnetic property can be adjusted.

[0065] The method can preferably be carried out using the device according to the invention or an advantageous development thereof. Therefore, the statements regarding the device according to the invention or one of its advantageous developments apply accordingly to the method according to the invention.

[0066] In an advantageous further development, the demagnetizing coils and the component for demagnetization are offset from one another, wherein a relative speed of up to 300 mm / s is preferably set along a movement axis.

[0067] The above-described refinement of the method is not limited to the manner in which the relative movement between the three demagnetizing coils and the component is generated. Rather, the relative movement can result from different movement components of the demagnetizing coils and the component. The movement axis is an axis along which the relative movement between the demagnetizing coils and the component can be described. In particular, a demagnetizing coil speed and a component speed can be projected at least partially onto the movement axis, which allows the resulting relative speed to be described.

[0068] It is within the scope of the advantageous development that the relative movement occurs by displacing the demagnetizing coils relative to a stationary component, or vice versa. Furthermore, it is within the scope of the advantageous development that the demagnetizing coils and the component are moved opposite to each other along the movement axis.

[0069] Investigations have shown that a relative speed of 200 mm / s enables good demagnetization of the component, so that even large-area components can be demagnetized in a short time.

[0070] In an advantageous further development, the alternating currents in the demagnetizing coils are each set at a frequency between 5 Hz and 50 Hz, in particular 30 Hz, and the component for demagnetization is brought at a distance of 5 mm from at least one of the demagnetizing coils.

[0071] Investigations have shown that at a frequency between 5 Hz and 50 Hz, especially 30 Hz, and a distance of 5 mm, a sufficient penetration depth of the magnetic field in the surface area of ​​common components can be achieved in order to demagnetize them.

[0072] In an advantageous development, the current intensities of the alternating currents are continuously reduced from a first amplitude to a second amplitude after demagnetizing the component. Preferably, the first amplitude is in the range between 10 amperes and 100 amperes, and the second amplitude is zero amperes. In an advantageous development, the component is rotationally symmetrical, in particular as a rotationally symmetrical rolling bearing ring with an outer diameter of at least 1 m. The relative movement comprises at least one rotational movement of the component, wherein the movement axis runs tangentially to a component surface.

[0073] An advantage of the development described above is that the demagnetization of the component is possible in a simple manner despite an outer diameter of at least 1 m. For this purpose, the demagnetization coils can be positioned in the arrangement as a polygon, either spatially fixed or movable relative to the component, and the component can be penetrated by the generated magnetic field in a circumferential surface area. In this case, a device with demagnetization coils can be used whose dimensions are independent of the dimensions of the component. In an embodiment in which the component is a rolling bearing ring, the surface area in which the component is demagnetized can be present on an outer circumferential surface or on an inner circumferential surface or on an end face of the rolling bearing ring.

[0074] Preferably, the component is rotationally symmetrical with an outer diameter of less than 6.0 m, in particular less than 1.0 m, in particular less than 0.5 m, preferably less than 0.1 m, most preferably less than 0.01 m. The component has an extension axis which extends orthogonally to at least one of the coil axes and in particular wherein the demagnetizing coils are arranged on an outer circumferential side of the component.

[0075] Further advantages and embodiments of the device and the method can be found in the following description of exemplary embodiments with reference to the figures.

[0076] It shows: Figure 1: a schematic representation of a device with three demagnetizing coils for demagnetizing a rolling bearing ring; Figure 2: the device when generating a spatially variable magnetic field at different times in views a), b) and c); Figure 3: the temporal course of three alternating currents in the demagnetizing coils of the device; Figure 4: two possible arrangements of the demagnetizing coils in one coil plane in views a) and b); Figure 5: a schematic representation of another device with six demagnetizing coils for demagnetizing a rolling bearing ring; Figure 6: a schematic representation of another device with three demagnetizing coils for demagnetizing a rolling bearing ring.

[0077] Figure 1shows a device 1 for demagnetizing a rotationally symmetrical component 2, which in this case is a rolling bearing ring. Due to the different manufacturing processes used to produce the component 2, it exhibits magnetic properties that are undesirable for various reasons. In particular, the magnetic properties complicate the application of non-destructive testing methods, such as eddy current testing. Therefore, there is a need to demagnetize the component 2 before it is tested, further processed, and assembled into an assembly.

[0078] One challenge in demagnetization is that the component 2 may have a plurality of component regions in which the preferred magnetic direction may be oriented differently. To demagnetize these component regions, it is possible to use the device 1 to generate a spatially variable magnetic field 9 (see FIG. Figure 2), which can be formed as a counter-field with a time delay relative to several Weiss domains during the demagnetization process. This allows the preferred magnetic directions to be aligned largely randomly, making it possible to reliably demagnetize even hard magnetic components. Alternatively, instead of demagnetization, a desired magnetic property of component 2 can be adjusted in the same way.

[0079] The device 1 comprises in the Figure 1 shown embodiment, three electrical demagnetizing coils 3, 4, 5 and a current source 6, which is designed as a power converter, which according to Figure 1connected to an electrical energy source 7. The demagnetizing coils 3, 4 and 5 are arranged in a common coil plane 8, each at a corner point of a triangle. The power converter in this case is designed as a three-phase inverter and serves to supply the demagnetizing coils 3, 4 and 5 with an alternating current I1, I2 and I3, respectively. The alternating currents I1, I2 and I3 have, as can be seen from Figure 3 shown, have a time-dependent, sinusoidal current intensity and are phase-shifted by 120° from each other.

[0080] By applying the alternating currents I1, I2 and I3 to the demagnetising coils 3, 4, 5, a magnetic field 9 is created which changes in time and space (cf. Figure 2 ), whose field lines 15 (cf. Figure 2) run at least partially parallel to the coil plane 8. The magnetic field 9 penetrates the component 2 in a surface area, whereby it can be demagnetized according to the above explanations.

[0081] The alternating currents I1, I2, I3 each have a frequency in the range between 5 Hz and 50 Hz. The demagnetizing coils 3, 4, 5 are arranged at a distance 10 of 5 mm from a tangential plane on the surface of component 2. During the demagnetizing process, the demagnetizing coils 3, 4, and 5 are in relative motion with respect to component 2, with the demagnetizing coils 3, 4, and 5 being stationary and the component 3 rotating about its axis of rotation 11. The tangential velocity 12 of component 2 corresponds, with respect to an axis 13, to the relative velocity between the demagnetizing coils 3, 4, and 5 with respect to component 2. The tangential velocity 12 is approximately 200 mm / s. The outer diameter 14 of component 2 is approximately 1 m.

[0082] As shown by Figure 2As shown, when the demagnetizing coils 3, 4, 5 are energized, the magnetic field 9 is generated, the field lines 15 of which run at least partially parallel to the coil plane. Due to a phase shift between the alternating currents I1, I2, I3 (cf. Figure 3 ) both the spatial position of the magnetic field 9 and the orientation of its field lines 15 change. This is shown in views a), b) and c) of the Figure 2 shown. Accordingly, the field lines 15 of the magnetic field 9 are aligned in a temporally successive manner along one of the sides of the triangle in which the demagnetizing coils 3, 4, and 5 are arranged, depending on the phase position of the alternating currents I1, I2, I3. As a result of such a spatial change in the magnetic field 9, it is possible to reliably demagnetize the component 2 (cf. Figure 1 ) in different spatial directions.

[0083] In views a) and b) of the Figure 4two alternative arrangements of the demagnetizing coils 3, 4, 5 in the coil plane 8 opposite the movement axis 13 are shown, which for the device 1 according to Figure 1 According to the opinion of a) the Figure 4 The demagnetizing coils 3, 4, 5 are arranged such that a first side 16 of the triangle in which the demagnetizing coils 3, 4, 5 are arranged is directed parallel to the movement axis 13. A second side 17 is directed orthogonally to the movement axis 13. A third side 18 is oriented at an acute angle to the movement axis 13.

[0084] According to view b) of the Figure 4 The demagnetizing coils 3, 4, 5 are arranged such that a first side 16 of the triangle in which the demagnetizing coils 3, 4, 5 are arranged is directed parallel to the movement axis 13. The two other sides 18, 18' are each oriented at an acute angle to the movement axis 13.

[0085] Figure 5 shows another device 1 with a total of six demagnetizing coils 3, 4, 5, 3', 4', 5', of which three demagnetizing coils 3, 4, 5 are arranged at the corners of a triangle which extends in a first coil plane 8 and three other demagnetizing coils 3', 4', 5' are also arranged at the corners of a triangle which, however, extends in a second coil plane 8'. The coil planes 8 and 8' are spaced apart essentially plane-parallel to one another and are each at a distance 10 and 10' respectively from the surface of the component 2 which is to be demagnetized.

[0086] The demagnetizing coils 3, 4, 5 are arranged with their end faces, which lie in the coil plane 8, at a distance of 10 or 10' from the end face of a component 2 to be demagnetized. The component 2 is a hollow cylinder of height D. The distances 10, 10' are each selected such that the demagnetizing coils 3, 4, 5 or 3', 4', 5' can form two magnetic fields, in whose interaction areas the component 2 is located and which change spatially and temporally. For the manner in which the magnetic field generated is shifted, please refer to the explanations for the Figures 1 to 4 referred to.

[0087] The demagnetizing coils 3, 4, 5, 3', 4', 5' are essentially cylindrical and each have a coil axis 3a or 4a or 5a or 3a', 4a', 4a', which each run orthogonally to the coil planes 8, 8'. In a manner not shown in detail here, the demagnetizing coils can also be triangular in cross-section or, at least in sections, comprise circular arc segments on the circumference.

[0088] The device 1 further comprises two power sources 7, 7', which are connected to the control units 6 and 6', respectively. The control unit 6 and the power source 7 serve, according to the explanations regarding Figure 1, to supply the demagnetizing coils 3, 4, 5 with a periodic alternating current I1, I2, or I3, respectively, in order to generate the spatially and temporally variable magnetic field. Accordingly, the control unit 6' and the current source 7' serve to supply the demagnetizing coils 3', 4', 5' with a periodic alternating current I1', I2', or I3', respectively, in order to generate the second magnetic field that is also spatially and temporally variable. Alternatively, the six demagnetizing coils 3, 4, 5, 3', 4', 5' can also be supplied with the alternating currents by means of only a single control unit 6 and a current source 7.

[0089] An advantage of the Figure 5The advantage of the device shown is that the dimensions of the component, particularly with regard to the height D, can be selected to be comparatively large. The demagnetization coils 3, 4, 5, 3', 4', 5' as well as the control units 6, 6' and the power sources can be dimensioned such that the component 2 is only superficially demagnetized on its end faces, or the magnetic fields penetrate the entire component. In a manner not shown here, the component 2 can be set in a rotational movement about its vertical axis, which can be advantageous for the demagnetization effect to be achieved.

[0090] Figure 6 shows a further device 1, which has three demagnetizing coils 3, 4, 5, whose coil axes 3a (not shown), 4a, 5b are arranged in a common coil plane 8. The demagnetizing coils 3, 4, 5 are each arranged at a corner point of a polygon, which also extends in the coil plane 8.

[0091] The demagnetizing coils 3, 4, 5 surround a component to be demagnetized, which in the example shown here is a cylinder with a main axis of extension. The coil axes 3a, 4a, 5a are directed toward the component 2.

[0092] According to the statements on Figure 1 The demagnetizing coils 3, 4, 5, in cooperation with the control unit 6 and the power source 7, are provided to generate a magnetic field that changes spatially and temporally. In particular, even with such an arrangement, a moving field can be generated that essentially corresponds to the statements regarding Figure 2 This allows component 2 to be demagnetized. If necessary, the component can be moved along its main axis of extension relative to the demagnetizing coils 3, 4, 5, 3', 4', 5'.

Claims

1. Device (1) for demagnetizing a component (2), comprising at least one demagnetizing coil (3, 4, 5, 3', 4', 5') and a current source (6, 7), which are arranged and configured to cooperate in order to form a magnetic field (9) in an interaction region of the demagnetizing coil (3, 4, 5, 3', 4', 5'), wherein the device (1) comprises at least three demagnetizing coils (3, 4, 5, 3', 4', 5'), which are arranged in a common coil plane (8) each at a corner point of a polygon, and the current source is configured to supply the demagnetizing coils (3, 4, 5, 3', 4', 5') each with a periodic alternating current (I1, I2, I3, I1', I2', I3'), wherein the alternating currents (I1, I2, I3, I1', I2', I3') in the demagnetizing coils (3, 4, 5, 3', 4', 5') are phase-shifted relative to one another in order to make the magnetic field (9) variable in space and time, characterized in that the demagnetizing coils (3, 4, 5, 3', 4', 5') each have a coil axis and are oriented such that the coil axes run orthogonally to the coil plane (8).

2. The device (1) according to claim 1, in which the demagnetizing coils (3, 4, 5, 3', 4', 5') of the polygon are arranged such that the magnetic field (9) can be formed with a plurality of field lines (15) which run at least partially between two adjacent demagnetizing coils (3, 4, 5, 3', 4', 5') and essentially parallel to the coil plane (8).

3. The device (1) according to claim 2, in which the current source (6, 7), in particular in cooperation with a controller, is configured to supply the demagnetizing coils (3, 4, 5, 3', 4', 5') with alternating current in such a way that the field lines (15) can be oriented at least partially essentially parallel to at least one side of the polygon, in particular can be oriented parallel to each side of the polygon with a time offset.

4. The device (1) according to any one of claims 1 to 3, with exactly three demagnetizing coils (3, 4, 5, 3', 4', 5'), wherein the polygon is a triangle.

5. The device (1) according to claim 4, in which the current source (6, 7) comprises a power converter, in particular a three-phase power converter, and the alternating currents (I1, I2, I3, I1', I2', I3') in at least two of the three demagnetizing coils (3, 4, 5, 3', 4', 5') are phase-shifted by 120° to one another.

6. The device (1) according to any one of the preceding claims, in which the current source (6, 7) is configured, in particular in cooperation with the controller, to set the alternating currents (I1, I2, I3, I1', I2', I3') each with a frequency between 5 Hz and 50 Hz.

7. The device (1) according to any one of the preceding claims, in which the current source (6, 7) is configured, in particular in cooperation with the controller, to continuously change the current intensities of the alternating currents (I1, I2, I3, I1', I2', I3') from a first amplitude to a second amplitude, wherein the second amplitude is smaller in magnitude than the first amplitude, preferably wherein the second amplitude is zero amperes.

8. The device (1) according to any one of the preceding claims, in which the demagnetizing coils (3, 4, 5, 3', 4', 5') are mounted in such a way that the demagnetization of the component (2) can be carried out during a relative movement between the demagnetizing coils (3, 4, 5, 3', 4', 5') and the component (2) along a movement axis (13).

9. The device (1) at least according to claim 8, in which the demagnetizing coils (3, 4, 5, 3', 4', 5'), in particular the three demagnetizing coils (3, 4, 5, 3', 4', 5'), are arranged such that, during the relative movement, at least a first side (16) of the polygon in the coil plane (8) is oriented parallel to the movement axis (13).

10. The device (1) at least according to claim 8, in which the demagnetizing coils (3, 4, 5, 3', 4', 5'), in particular the three demagnetizing coils (3, 4, 5, 3', 4', 5'), are arranged such that, during the relative movement, at least a second side (17) of the polygon in the coil plane (8) is oriented orthogonally to the movement axis (13).

11. The device (1) at least according to claim 8, in which the demagnetizing coils (3, 4, 5, 3', 4', 5'), in particular the three demagnetizing coils (3, 4, 5, 3', 4', 5'), are arranged such that, during the relative movement, at least a third side (18, 18') of the polygon in the coil plane (8) is oriented at an acute angle to the movement axis (13).

12. The device (1) at least according to claim 1, in which the device (1) comprises at least six demagnetizing coils (3, 4, 5, 3', 4', 5') which are arranged in two coil planes (8, 8'), wherein three of the six demagnetizing coils are each arranged at a corner point of a first polygon which extends in a first coil plane (8) and wherein three other of the six demagnetizing coils (3', 4', 5') are each arranged at a corner point of a second polygon which extends in a second coil plane (8').

13. Method for demagnetizing a component (2), by means of at least a demagnetizing coil (3, 4, 5, 3', 4', 5') with an interaction region in which a magnetic field (9) is generated and in which the component (2) is arranged, wherein at least three demagnetizing coils (3, 4, 5, 3', 4', 5') are provided, which are each arranged at a corner point of a polygon in a coil plane (8), and wherein the demagnetizing coils (3, 4, 5, 3', 4', 5') are each supplied with a periodic alternating current (I1, I2, I3, I1', I2', 13'), wherein the alternating currents (I1, I2, I3, I1', I2', I3') in the demagnetizing coils (3, 4, 5, 3', 4', 5') are phase-shifted with respect to one another and the magnetic field (9) changes spatially and temporally and wherein the component is demagnetized in the interaction region by means of the magnetic field (9), characterized in that the demagnetizing coils (3, 4, 5, 3', 4', 5') each have a coil axis and are oriented such that the coil axes run orthogonally to the coil plane (8).

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