Device for determining the magnetic properties of ring samples

Abstract

The invention relates to a device for determining the magnetic properties of ring samples with an outer primary winding and a secondary winding arranged inside the primary winding for receiving a test specimen, characterized in that the primary winding is designed in the form of a base part formed from radially outwardly extending first conductor pieces and a cover part formed from radially outwardly extending second conductor pieces, which is detachably connected to the base part, wherein the base part and the cover part are detachably connected to each other and form a toroidal cavity in which the secondary winding is arranged, wherein two adjacent first conductor pieces are contacted by means of a second conductor piece such that the base part and cover part form a winding.

Description

[0001] The invention relates to a device for determining the magnetic properties of ring samples according to the preamble of the first claim.

[0002] The magnetic properties of materials are usually specified in the form of the magnetization characteristic and the frequency- and output-dependent loss characteristics.

[0003] Typically, three basic geometries or methods are used to determine the magnetic properties of material samples, involving a ring sample, an Epstein frame, or a single-sheet tester. The field strengths are determined using physically measurable electrical quantities. For this, the closed magnetic circuit must be magnetized, which is usually achieved using a magnetizing winding (primary winding) energized with alternating current. The magnetic field strength can then be calculated from the measured current and the geometry of the experimental setup. The measurement of magnetic flux density is often based on the transformer principle. For this, a second winding (secondary winding) is wound around the closed magnetic circuit, in which a voltage is induced by the alternating magnetic flux. Together with the geometry of the experimental setup, the magnetic flux density can be calculated.

[0004] The magnetization characteristic is composed of the reversal points of hysteresis loops as the magnetic field strength of the material sample increases. The associated remagnetization losses are also calculated from the electrical measurements.

[0005] According to industry standards, the measurement is performed using an Epstein frame, a method standardized according to DIN EN 60404-2. A rectangular magnetic circuit is created by stacking strips of sheet metal, which overlap at the corners. Advantages include extensive standardization, widespread use, and the ease of sample insertion and replacement. The sample holder already carries the primary and secondary windings on coil holders, into which the rectangular strips of sheet metal are then individually inserted.

[0006] Disadvantages of measurement using an Epstein frame include a number of systematic errors and problems in the operation of an Epstein frame.

[0007] Another method is the aforementioned Single Sheet Tester (SST). This method is standardized according to DIN IEC 60404-3. In this method, the test specimen is a single sheet of metal. The magnetic circuit is closed via a magnetic feedback loop (yoke), therefore the closed circuit consists partially of material not belonging to the test specimen. The yoke carries the primary winding. Either the secondary winding is wound around the test specimen, or alternatively, another method using field-measuring coils is employed. In any case, the measurement of field strength and flux density is complicated by the mixture of the specimen and the yoke in the magnetic circuit, as well as by the geometry of the sheet.

[0008] The third common geometry is a toroid with a typically rectangular cross-section. The measuring principle, with primary and secondary windings, is similar to that of the Epstein frame. The method is standardized in DIN EN 60404-6. A key advantage is the closed magnetic circuit without foreign material or air gaps, resulting in low systematic errors. Unlike the first two methods, the magnetic circuit cannot be opened.

[0009] This results in a significant disadvantage. Applying the windings is much more complex than with the aforementioned state-of-the-art methods. Both windings, the primary and the secondary windings, must be individually applied for each sample, often by hand if no dedicated winding machine is available. The number of turns can easily exceed 100. In contrast to the aforementioned methods, the reproducibility of the winding geometry is limited. Another disadvantage is that the windings on a ring sample are not reusable, and valuable raw materials are consumed with each sample. In contrast, largely automated test rigs are available for purchase for methods using Epstein frames or single-sheet testers, which can, for example, be integrated into a production line.

[0010] The publication JP S58 - 101 178 U describes a device with an upper and a lower semicircular element, the semicircular elements being connected via plug contacts. The secondary winding is not closed when the primary winding is closed. Dimensionally stable support elements are used, which carry a conductor.

[0011] An electrical connection using plug contacts is described in the publication JP S62 - 158 371 U. Plug contacts have the disadvantage that a large force is required to open and close them when there are many contact points. Therefore, a push-fit plunger is used to close the connection.

[0012] The object of the invention is to develop a device for determining the magnetic properties of ring samples, whereby the time-consuming application of the primary and secondary windings is to be simplified and accelerated. Furthermore, the winding is to be designed to be geometrically reproducible and reusable.

[0013] This problem is solved using the features of the first patent claim.

[0014] Advantageous embodiments result from the dependent claims.

[0015] The device for determining the magnetic properties of ring samples has an outer primary winding and a secondary winding arranged inside the primary winding for receiving a test specimen, wherein the primary winding is formed in the form of a base part consisting of radially outwardly extending first conductor pieces and a cover part consisting of radially outwardly extending second conductor pieces, which is detachably connected to the base part, wherein the base part and the cover part are detachably connected to each other and form a toroidal cavity in which the secondary winding is arranged, wherein two adjacent first conductor pieces are contacted by means of a second conductor piece such that the base part and cover part form a winding.

[0016] The secondary winding comprises a lower and an upper circuit board, with both boards carrying conductor tracks that are connected to each other via spring contacts when the base is joined to the top, such that the conductor tracks and spring contacts form a continuous winding. The secondary winding can be simple or differential.

[0017] The second conductor sections of the cover plate are mounted with some play on the cover plate and pre-tensioned by means of a first spring stage. This play ensures a reliable electrical connection between the first and second conductor sections. The spring pre-tension is preferably achieved via a non-conductive plastic screw, which pre-tensions the second conductor section against the cover plate. The second conductor sections have a threaded bore to accommodate the screw. According to the invention, a second spring stage is arranged between the second conductor sections of the cover part and the cover plate. The second spring stage between the cover plate and the top plate is achieved using elastic material pads. These pads are positioned in the recess between the top plate and the cover plate, above the contact points between the cover plate and the bottom plate. They act as a buffer between the cover plate and the cover plate when the cover plate is placed on the bottom plate and become effective when the spring is fully compressed. Preferably, the bottom plate and / or the cover plate has individual U-shaped conductor segments extending radially to the longitudinal axis of the device, forming the cavity for the secondary winding. These conductor segments of the bottom plate and / or cover plate create a U-shaped current path.

[0018] For optimal power transmission, the conductor sections of the primary winding are preferably designed to be dimensionally stable and can transfer the locking force to the secondary winding.

[0019] Advantageously, the base part is arranged in a base plate and the cover part in a lid plate, with the loosely arranged conductor sections being fixed in their position within the base plate and lid plate. The base plate and lid plate have guides by means of which the components are aligned with each other. Preferably, the base plate has cylindrical pins arranged circumferentially in the edge region of the base plate. The lid plate has bores that can be engaged with the cylindrical pins.

[0020] In an advantageous embodiment of the invention, the first conductor sections of the base part are arranged in corresponding molded elements in the base plate. In a particularly advantageous embodiment, the second conductor sections of the cover part are arranged in corresponding molded elements in the cover plate. The first and second conductor sections are spaced apart from each other within a plate. The molded elements can be designed as recesses or lateral guides that extend partially or completely along the side surfaces of the conductor sections.

[0021] The second spring stage can advantageously be designed in the form of silicone pads. Alternatively, machine springs or other elastic material pads are conceivable. The springs can have a different, and in particular a harder, spring rate than the first spring stage.

[0022] Preferably, the primary and secondary windings are closed by a central force application along the longitudinal axis. Particularly preferably, the central force application is achieved by means of a screw connection via a threaded rod in the field-free region in the center of the toroidal primary and secondary windings. However, other mechanical designs are also possible. For example, a spring above each contact can be used to apply force in a ring shape. Other forms of force application are also possible, such as via toggle levers, lever locks, or hydraulic or pneumatic cylinders.

[0023] In one embodiment, the circuit boards of the secondary winding can have an electrical shield to decouple the primary and secondary windings.

[0024] Preferably, spacer plates are arranged between the primary and secondary windings, by means of which force is transmitted from the outer primary winding, and in particular from the second conductor sections, to the secondary winding. For this purpose, the spacer plates can be connected to the circuit boards.

[0025] In an advantageous embodiment, the upper and lower spacer plates have additional axial guides that secure the secondary winding against incorrect assembly.

[0026] Furthermore, means for supplying power to the primary and secondary windings are provided, wherein a first conductor piece and a second conductor piece have means for contacting a power source.

[0027] According to the invention, the primary and secondary windings are divided into two parts. The upper half is attached to a cover plate and the lower half to a base plate, so that when the cover plate is pressed onto the base plate, all windings of the primary and secondary windings are closed simultaneously. When the primary winding is closed, its conductor segments simultaneously press the two circuit boards and spring contacts of the secondary winding together via the spacer plates. Therefore, only one central screw is required, which presses the circuit boards of the secondary winding together, closes both windings simultaneously, and makes contact. To avoid distorting the measurement, the screw, nut, and washers are made of austenitic, non-ferromagnetic stainless steel. Furthermore, the screw is located in the field-free region in the center of the toroid.

[0028] The invention is explained in more detail below using an exemplary embodiment and accompanying drawings.

[0029] They show: Fig. 1. A representation of the primary winding, Fig. 2. the power flow in a section of the primary winding's turns Fig. 3 the current flow in a section of the turns of the primary winding according to Fig. 2, Fig. 4 a base part with attached cover part inserted into a base plate, Fig. 5 A top view of a base plate with an inserted base section. Fig. 6 a cover part arranged in a cover plate, Fig. 7 a sectional view of the device with primary winding, Fig. 8 another cross-sectional view of the primary winding, Fig. 9 a top view of a base plate according to Fig. 4 with a circuit board with spring contacts and ring test, Fig. 10 a sectional view of the device with the secondary winding inserted, Fig. 11 a device in a side view.

[0030] Fig. Figure 1 shows a schematic representation of the primary winding 1 of a device according to the invention. In the Fig. 2 and Fig. Figure 3 shows a section of the primary winding 1.

[0031] The primary winding 1 has a toroidal base section 2 and a toroidal cover section 3 resting on or attached to it, the base section 2 and the cover section 3 forming a toroidal cavity. The base section 2 is formed from radially outward extending first conductor sections 4. The cover section 3 is formed from radially outward extending second conductor sections 5. The first and second conductor sections 4, 5 are not connected to their adjacent conductor sections and are loosely arranged relative to each other. The cover section 3 has curved conductor sections 5, each of which connects two adjacent conductor sections 4 of the base section 2 to form turns. By this configuration, a closed winding is formed when the cover section 3 is placed on the base section 2. The placement of all second conductor sections 5 onto the first conductor sections 4 occurs simultaneously. According to the Fig. 2 and Fig. In section 3, the first conductor sections 4 are arranged side by side and spaced apart from each other. The first conductor sections 4 have a U-shaped form, with the conductor sections or the cavities of the conductor sections forming a toroidal groove. The first and second conductor sections 4, 5 form a cavity enclosed by the conductor sections 4, 5, into which the secondary winding with the ring test piece can be inserted.

[0032] The first conductor sections 4 of the outer primary winding 1 are solid and therefore mechanically dimensionally stable. This allows the locking force F to be applied according to the Fig. 2 and Fig. 3. The force is transferred from the second conductor sections 5 to the first conductor sections 4. The contact force between conductor sections 4 and 5 creates the electrical connection between them. Furthermore, the locking force for the secondary winding (not shown here) is transferred from the primary winding. Fig. Figure 3 shows, in addition to the applied locking force F, the current flow I within the primary winding of the device.

[0033] The Fig. 4 and Fig. Figure 5 shows a base part 2 in a base plate 6, wherein Fig. 4 represents a superimposed cover part 3, which together with the base part 2 forms the primary winding 1. In Fig. Figure 6 shows the corresponding cover part 3 in a cover plate 7. A sectional view of the connected base plate 6 and cover plate 7 is shown in the Fig. Figure 7 shows the base plate 6 and the cover plate 7, which are square in shape. They are aligned with each other by means of guides in the form of four cylindrical pins 8 and corresponding bores 9 in the area of ​​the corners of the cover plate and base plate, and are screwed together via a central threaded rod 10. Screwing the cover plate 7 and base plate 6 together closes the primary winding 1 and the secondary winding. A central force is introduced via the threaded rod 10 in the field-free region at the center of the toroidal primary winding and the secondary winding (not shown). The threaded rod 10 is mounted to the base plate by means of nuts 11. The cover plate 7 has a bore 12 through which the threaded rod 10 passes when mounted. It is secured to the cover plate by means of another nut 11 on the top side of the cover plate.Other forms of force application would also be possible, for example via toggle levers / toggle locks / hydraulic or pneumatic cylinders. The first conductor segments 4 of the outer primary winding 1 are solid and therefore mechanically dimensionally stable with respect to the force application. With this design, the locking force can be transferred to the inner secondary winding. The first ladder sections 4 of the U-shaped base section 2 are arranged in corresponding molded elements, in particular in the form of recesses 13 in the base plate 6. Furthermore, the second ladder sections 5 of the cover section 3 are arranged in corresponding molded elements in the form of recesses 14 in the cover plate 7.

[0034] The second conductor sections 5 have a bore 15 with an internal thread, by means of which the second conductor sections 5 are suspended with play from the cover plate 7 by means of a screw 16 and a spring 17, respectively, under preload. The screw 16 is preferably an insulating plastic screw and is screwed through the cover plate 7 into the internal thread of the bore 15 of the conductor section 5.

[0035] A second spring stage between the cover part 3 and the lid plate 7 is implemented by means of a silicone pad 18. The silicone pad 18 is arranged in the recess 14 between the lid plate 7 and the cover part 3 above the contact points of the cover part 3 and the base part 2 and forms a buffer between the cover plate 7 and the cover part 3 when the cover part 3 is placed on the base part 2 and becomes effective when the spring 17 is fully immersed.

[0036] A simplified sectional view of the primary winding 1 between a base plate 6 and a cover plate 7 is shown in the Fig. Figure 8 shows the base plate 6 being positioned relative to the cover plate 7 by means of the cylindrical pins 8. The toroidal cavity for receiving the secondary winding (not shown) is formed between the U-shaped first conductor sections 4 of the base part 2 and the second conductor sections 5 of the cover part 3.

[0037] An arrangement of a secondary winding 20 with ring sample 19 within a base part 2 according to Fig. 4 and Fig. 5 is in Fig. Figure 9 shows a sectional view of a device with a primary winding 1 and a secondary winding 20. Fig. Figure 10 shows the components of the primary winding 1. The components correspond to the design shown in Figure 10. Fig. 7. The ring sample 19 is arranged on a lower circuit board 21, with the ring sample 19 extending approximately in the region of the outer circumference of the lower circuit board 21. The lower circuit board 21 has individual conductor tracks which are connected to a second upper circuit board 22 by means of spring contacts 23 arranged on both sides along the ring sample to form a closed winding in the form of the secondary winding 20. The closing force F is also transmitted to the inner secondary winding 20 by the spring 17 and the cover part 3.

[0038] Between the base part 2 and the lower circuit board 21, according to Fig. A first spacer plate 24 is arranged in section 10. Furthermore, a second spacer plate 25 is arranged between the cover part 3 and the upper circuit board 22. The spacer plates 24 and 25 ensure force transmission from the primary winding 1 to the secondary winding 20, insulate the circuit boards 21 and 22 from the primary winding 1, provide clearance for solder joints of the spring contacts on the underside of circuit board 21, and ensure the central positioning of the ring probe 19 within the secondary winding 20.

[0039] A device with a base plate 6 and a cover plate 7 is in Fig.Figure 11 shows the base plate 6 and cover plate 7, which are made of transparent acrylic glass and aligned relative to each other by means of cylindrical pins 8. They are screwed together via a central force transmission point using a threaded rod 10 and corresponding nuts 11. The second conductor sections 5 are mounted to the cover plate 7 by means of plastic screws 14 and connected to the first conductor sections 4 in such a way as to form a winding. For current supply, contacts 26 to a power source are provided on opposite sides of the first conductor sections 4 and the second conductor sections 5. The ring-shaped silicone pad 18 is arranged between the cover plate 7 and the second conductor sections 5 in the edge region of the second conductor sections 5.

[0040] The present invention simplifies and accelerates the complex winding of samples and allows the winding to be designed in a geometrically reproducible manner and reused.

[0041] The present invention combines the ease of handling and geometric reproducibility of the winding of single sheet testers and Epstein frames with the advantages of measurement with a ring-shaped geometry. It enables quick, simultaneous opening and closing of both windings. Reference symbol list 1 Primary winding 2 Base section 3 Cover part 4 first ladder sections 5 second ladder sections 6 Base plate 7 Cover plate 8 cylinder pin 9 bore 10 threaded rods 11 Mother 12 bore 13. Further Study 14 In-depth study 15 holes with internal thread 16 screws 17 spring 18 silicone pads 19 Ring test 20 Secondary winding 21 Lower circuit board 22 Top circuit board 23 Spring contact 24 Lower spacer plate 25 Upper spacer plate 26 Contacting

Claims

[1] Device for determining magnetic properties of ring samples with an outer primary winding (1) and a secondary winding (20) arranged inside the primary winding (1) for receiving a test specimen, characterized by , that the primary winding (1) is formed in the form of a base part (2) consisting of radially outwardly extending first conductor pieces (4) and a cover part (3) consisting of radially outwardly extending second conductor pieces (5) which is detachably connected to the base part (2), wherein the base part (2) and the cover part (3) are detachably connected to each other and form a toroidal cavity in which the secondary winding (20) is arranged, wherein two adjacent first conductor pieces (4) are contacted by means of a second conductor piece (5) such that the base part (2) and cover part (3) form a winding, - wherein the secondary winding has a lower circuit board (21) and an upper circuit board (22), - wherein the circuit boards (21, 22) have conductor tracks which are contacted together via spring contacts (23) when connecting the base part (2) with the cover part (3) such that the conductor tracks and the spring contacts (23) form a continuous winding, - wherein the second ladder sections (5) of the cover part (3) are received with play on a cover plate (7) and are pre-tensioned by means of a first spring stage and - the second conductor pieces (5) have a bore (15) with an internal thread, by means of which the second conductor pieces (5) are suspended with play from the cover plate (7) under preload via a screw (16) and a spring (17) and that - between the second conductor sections (5) of the cover part (3) and the cover plate (7) a second spring stage is arranged which is realized by means of elastic material supports (description page 4, lines 21 and 22), wherein the elastic material support is arranged in a recess (14) between the cover plate (7) and the cover part (3) over the contact points of the cover part (3) and the base part (2) and forms a buffer between the cover plate (7) and the cover part (3) when the cover part (3) is placed on the base part (2) and becomes effective when the spring (17) is fully immersed. [2] Device according to claim 1, characterized by , that the bottom part (2) and / or the top part (3) consists of individual u-shaped ladder sections. [3] Device according to any of the preceding claims, characterized by , that the first and / or second ladder sections (4, 5) of the bottom part (2) and top part (3) are dimensionally stable. [4] Device according to any of the preceding claims, characterized by , that the base part (2) is arranged in a base plate (6) and the top part (3) is arranged in a cover plate (7) and that the base plate (6) and the cover plate (7) are aligned to each other by means of guides (8). [5] Device according to any of the preceding claims, characterized by , that the first ladder pieces (4) of the bottom part (2) are arranged in corresponding shaped elements in the bottom plate (6) and / or that the second ladder pieces (5) of the top part (3) are arranged in corresponding shaped elements in the top plate (7), wherein the ladder pieces (4, 5) are spaced apart from each other within a plate (6, 7). [6] Device according to any of the preceding claims, characterized by that the second spring stage is designed in the form of silicone pads and / or machine springs. [7] Device according to claim 6, characterized bythat the springs have a harder spring rate than the first spring stage. [8] Device according to any of the preceding claims, characterized by , that the primary and secondary winding (1, 20) is closed by a central force application along the longitudinal axis of the device. [9] Device according to any of the preceding claims, characterized by , that the circuit boards (21, 22) have an electrical shield for decoupling the primary and secondary windings (1, 20). [10] Device according to any of the preceding claims, characterized by , that a first conductor (4) and a second conductor (5) have means for contacting (26) with a power source. [11] Device according to any of the preceding claims, characterized by, that a lower spacer plate (24) and an upper spacer plate (25) are arranged between the primary winding (1) and the secondary winding (20), by means of which a force transmission from the outer primary winding (1) to the secondary winding (20) takes place. [12] Device according to any of the preceding claims, characterized by , that the lower spacer plate (24) is connected to the lower circuit board (21) and the upper spacer plate (25) is connected to the upper circuit board (22). [13] Device according to claim 12, characterized by , that the upper and lower spacer plates (24, 25) have axial guides which secure the secondary winding (20) against incorrect assembly.

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