Method and apparatus for manufacturing band ring core
The device and method for manufacturing banded ring cores address the challenges of forming uniform magnetic circuits and minimizing eddy current losses by using adjustable winding and separation techniques, resulting in improved magnetic properties and higher frequency operation.
Patent Information
- Application Number
- JP2024566869
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-05-13
- Filing Date
- 2023-05-15
- Publication Date
- 2025-05-20
AI Technical Summary
Existing methods for manufacturing banded ring cores, such as those used in transformers and chokes, face challenges in efficiently forming closed magnetic circuits with uniform cross-sections and minimizing eddy current losses, particularly at higher frequencies, while handling brittle materials like amorphous and nanocrystalline alloys.
A device and method involving adjustable winding mandrels, strip feeders, separation devices, and coating mechanisms are used to wind soft magnetic strips into multiple layers, apply insulating layers, and form closed rings with varying strip widths, utilizing separating plates and clamping straps to create banded ring cores with controlled geometry and reduced eddy currents.
The method enhances the production of banded ring cores with improved magnetic properties and reduced eddy current losses, enabling higher frequency operation and mechanical robustness, particularly suitable for transformers and chokes.
Smart Images
Figure 2025515859000001_ABST
Abstract
Description
[Technical field]
[0001] The present invention relates to a method and apparatus for manufacturing banded ring cores, such as those used for transformers or chokes. [Background technology]
[0002] A choke is a coil or inductor for limiting the current in an electrical line, for temporarily storing energy in the form of a magnetic field, for impedance matching or for filtering. Most chokes have a magnetic core, since in this case the choke requires significantly fewer turns than an air choke for the same inductance.
[0003] A transformer usually consists of two or more coils, usually wound with insulated copper wire, located on a common magnetic core. Transformers are used, for example, to change voltages in energy supply installations and technical equipment. Furthermore, transformers are needed for signal transmission and protective isolation.
[0004] The magnetic core is made of a soft magnetic material with the highest possible saturation flux density and high magnetic permeability, which allows the magnetic flux that occurs when electricity flows through the conductor of the coil to be bundled and guided with little loss, increasing the inductance. The high magnetic permeability increases the magnetic field of the inductor by up to 10^5 compared to an inductor with air as a core, so that the dimensions of an inductor with a magnetic core can be smaller than for an air coil.
[0005] To combat eddy current losses, magnetic cores of transformers and electric motors are not constructed solidly but are laminated in "multilayers". These stamped or cut electric sheets are coated with a heat-resistant and insulating varnish and layered into blocks or wound into rings, oriented parallel to the magnetic field lines. The magnetic flux is thus split into individual magnetic fluxes separated from each other in the individual sheets, so that only relatively small eddy currents can form in the individual sheets, and the loss power is significantly smaller than that in solid materials as a whole. The sheets are usually thinner than 1 mm. The thinner the sheet, the lower the eddy current losses or the higher the operating frequency can be.
[0006] Laminated magnetic cores are mainly used in the lower frequency range from 16 Hz to 400 Hz, although wound strip cores with strip thickness of about 20 μm can be used up to 100 kHz. However, at higher frequencies, powder cores or ferrite are mainly used for the cores of transformers, coils and chokes.
[0007] The ribbon core is wound from a thin soft magnetic ribbon with a thickness between 20 μm and 1 mm (typically depending on the alloy). The easiest and most economical form to manufacture is the ribbon ring core. Thus, an ideal closed magnetic circuit with a uniform cross section is formed, except for negligible transitions between the ribbon layers. The dynamic characteristics are mainly controlled by the alloy used and the ribbon thickness.
[0008] A strip ring core is usually made from a long strip, which typically must first be cut to the appropriate width. Therefore, a strip ring core is also called a strip cut core. The strip is wound onto the core using a winding machine. Winding is followed by a heat treatment during which the magnetic properties of the core are adjusted or obtained, between about 200°C and 600°C depending on the alloy. During the heat treatment, the material is changed not only magnetically but also mechanically. Amorphous and nanocrystalline alloys are very brittle after heat treatment and can therefore be easily damaged mechanically.
[0009] Hereinafter, an improved method and apparatus for manufacturing a band ring core is proposed.
[0010] The proposed device for manufacturing the strip ring core comprises: a winding device having two mutually spaced, rotatably drivable winding mandrels for winding up the ribbon, the winding mandrels being selectively rotatably drivable about a respective first rotation axis or about a common second rotation axis, the winding mandrels being movable perpendicularly to the rotation axes in order to adjust the spacing between the winding mandrels; two strip feeders each having at least one strip coil for providing a soft magnetic strip; an insertion device having at least one manipulator for inserting a separation plate piece into the formed strip; at least one separating device for separating the strip wound in a stepped manner to form a plurality of strip portions; Equipped with.
[0011] According to a further embodiment of the proposed device, The strip supplying device has at least two strip coils for providing soft magnetic strips of different widths, Each of the belt supplying devices has a multi-coil magazine, and at least two belt coils can be replaceably attached to the multi-coil magazine; - A belt tightening device is provided to maintain a specified belt tension, A coating device is provided for applying an insulating layer or a connecting layer to the strip; A coil supply device having a manipulator for receiving the coil and transferring it onto the strip portion is provided, a closing device is provided having a manipulator for deforming the free ends of the strap portions into a closed ring, The closing device has a manipulator that attaches a tightening strap that encircles the entire magnetic core.
[0012] The method for producing a band ring core according to the present invention comprises the steps of: Providing a soft magnetic strip on at least two strip coils; unwinding the strip from the two strip coils and winding the strip onto two spaced apart winding mandrels by rotating the winding mandrels about their respective first rotation axes to form first strip windings of multiple layers, and inserting a separating plate piece into the first strip winding as each of the multiple layers is formed; decreasing the spacing between the winding mandrels until the first strip windings contact each other; - unwinding the ribbon from the two ribbon coils and rotating the winding mandrel about a common second axis of rotation to form a multi-layered second ribbon winding that is wound around the first ribbon winding, and inserting a separating plate piece into the second ribbon winding that is being formed after each of a plurality of layers is formed; - step of separating the strip body stepwise to form a plurality of strip portions; receiving at least one coil and fixing the coil onto the strip; - deforming the free ends of the strip and connecting the ends of the strip to form a closed ring; has.
[0013] According to another aspect of the proposed device, For each winding mandrel, providing strips of different widths on at least two strip coils, - Applying an insulating layer or a connecting layer onto the strip while unwinding and winding the strip; The final step is to attach a clamping strap or structure that encircles the entire magnetic core. A first strip winding is formed on a winding mandrel consisting of at least two strips of different widths that increase in width from the inside to the outside, and a second strip winding is formed on the first strip winding, also consisting of at least two strips of different widths that decrease in width from the inside to the outside.
[0014] The device and method are explained in greater detail below in an exemplary manner with reference to the drawings. [Brief description of the drawings]
[0015] [Figure 1a] 1 shows a schematic front view of the process of winding a strip. [Figure 1b] 1 shows a schematic front view of the process of winding a strip. [Figure 1c] 1 shows a schematic front view of the process of winding a strip. [Figure 1d] 1 shows a schematic front view of the process of winding a strip. [Figure 2a] 1 shows a schematic diagram of the process of winding a strip as viewed from above. [Figure 2b] 1 shows a schematic diagram of the process of winding a strip as viewed from above. [Figure 3a] 1 shows a schematic process of cutting off the ribbon, fixing the coils and connecting the ribbon parts. [Figure 3b] 1 shows a schematic process of cutting off the ribbon, fixing the coils and connecting the ribbon parts. [Figure 3c] 1 shows a schematic process of cutting off the ribbon, fixing the coils and connecting the ribbon parts. [Figure 3d] 1 shows a schematic process of cutting off the ribbon, fixing the coils and connecting the ribbon parts. [Figure 3e] 1 shows a schematic process of cutting off the ribbon, fixing the coils and connecting the ribbon parts. [Figure 3f] 1 shows a schematic process of cutting off the ribbon, fixing the coils and connecting the ribbon parts. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0016] The drawings in Fig. 1a to 1d show an apparatus for producing strip ring cores in a front view. The apparatus has two strip coils 3 providing a thin soft magnetic strip 1, two rotatably drivable winding mandrels 5 for winding the strip 1 to form multi-layer strip windings 8, 9, the distance between which is adjustable relative to one another, and two nozzles 10 of a coating device for applying an insulating or connecting layer onto the strip 1. The winding mandrels 5 can be rotatably driven separately about a first axis of rotation 6 or together about a second axis of rotation 7, the first axis of rotation 6 and the second axis of rotation 7 being aligned parallel to one another. In cross section, the winding mandrels 5 have a rectangular shape adapted to the transformer to be produced, in which case frame elements 14 of a holding frame can already be inserted into the winding mandrels 5. It is not important for the proposed method whether the strip 1 is used as a single-layer strip or as a multi-layer strip, but only affects the productivity of the proposed apparatus.
[0017] As shown in the top view in Figures 2a and 2b, the strip supplying device not only has an individual strip coil 3 for each winding mandrel 5, but also has one multi-coil magazine 4 in each case, in which four strip coils 3 with strips 1 of different widths can be interchangeably mounted. Thereby, after a certain number of layers of a strip 1 of a certain width, the multi-coil magazine 4 is switched over, followed by continuing the winding with a strip 1 of a larger width, so that the first strip winding 8 consists of up to four strips of different widths, increasing in width from the inside to the outside, on the winding mandrel 5. Winding starts with the narrowest strip 1. When the desired thickness of this strip 1 is reached, winding is interrupted, the strip 1 is separated, the next wider strip 1 is connected to the narrower strip 1 (for example by means of a double-sided adhesive strip), and then the winding process is continued.
[0018] When the strip 1 is wound onto the two first strip bodies 8 for the later required separation process, a separating plate piece 11, as shown in FIGS. 3 a to c, is inserted for each strip thickness of, for example, about 5 mm. The separating plate piece 11 should prevent the underlying material layer from being cut during the separation cut. The separating plate 11 can be made of various materials, since it is removed after the separation cut. It is not important whether the separating plate piece 11 is cut or whether a cut-out of the separating plate piece 11 is located at the separation point. The separating plate piece 11 can be advantageously made of a permanent magnet, which allows simple fixing and also simple removal after the separation cut. In the case of an arrangement with permanent magnets, a cut-out is provided.
[0019] When the desired thickness of the second ribbon width is reached, the third and fourth ribbon widths are wound in a similar manner, except that the last (widest) ribbon width is wound only to half its desired thickness. The winding of the ribbon 1 on the winding mandrels 5 by rotation about their respective first rotation axes 6 is shown in Figures 1b and 2a.
[0020] The winding devices are then stopped and the winding mandrels 5 are moved closer to each other in a plane perpendicular to the rotation axes 6, 7 until the first strip windings 8 come into contact with each other (as shown in fig. 1c and 2b). Unwinding from both strip feeders is then performed simultaneously on both previously formed first strip windings 8, by driving both winding mandrels 5 together in rotation about a second rotation axis 7 arranged between them, as a result of which a second strip winding 9 is formed which surrounds both first strip windings 8 (as shown in fig. 1d and 2b).
[0021] In this case, the band width is reduced by one step in each case after the desired thickness has been reached, which results in a generally elliptical core cross-sectional geometry.
[0022] As described above, when the strip 1 is wound onto the second strip body 9, once the desired layer thickness has been reached, the separation plate piece 11 is positioned at the desired separation position and inserted into the second strip body 9 that is being formed.
[0023] If it is necessary to coat the strip 1 with an insulating or connecting layer, the insulating or connecting layer may be applied successively during the winding process, but in this case multiple strips 1 must not be used. After the winding process is finished, a strip roll 8, 9 is provided, as shown in Figure 3a.
[0024] After the winding process is completed, the (upper) part of the core holding device 14 is assembled as shown in Fig. 3b. Afterwards, the core can be removed from the device and the strip rolls 8, 9 have to be cut open in order to position and fix the coil 13. In Fig. 3b it is shown how the separating device 12 cuts the first winding layer of the outer second strip roll 9 up to the just inserted separating plate piece 11. In Fig. 3c all winding layers of the outer second strip roll 9 have been cut, whereby the separating device has just started to cut the first winding layer of one of the two inner first strip rolls 8 up to the just inserted separating plate piece 11.
[0025] The strips 8, 9 are cut by a separating device 12, for example by means of a separating grinding disk. The separation process takes place at the point where the separating plate pieces 11 are inserted, from the outside respectively to the separating plate pieces 11, with a cutting width that is as small as possible (for example about 1 mm to 2 mm).
[0026] Next, the cut-open end of the strip portion 2 falls downward due to gravity, releasing the next separation point. Once all separation steps are completed and the free end of the strip portion 2 formed by cutting hangs down (FIG. 3d), the coil 13 can be fitted onto the free end of the strip portion 2, or the coil 13 is positioned and prepared, and the free end of the strip portion 2 is inserted into the coil 13 (FIG. 3e).
[0027] Thereafter, the (lower) part of the holding device 14 is positioned and fixed on the core (FIG. 3e), after which the open legs 2 are closed starting from the middle (FIG. 3f), whereby positioning is performed in such a way that the free ends of the strip parts 2 are brought into abutment against one another almost abuttingly, and this is possible by pushing the lower holding frame 14 towards the upper holding frame 14 by half the cutting width.
[0028] To aid in the closing process, a cinching strap should be placed around the fully wound transformer core, which may already be secured together at the upper holding frame 14 .
[0029] After closing the core ring, the lower holding frame 14 is further completed (FIG. 3f). This forms the basic structure of the transformer consisting of the core, coil 13 and holding frame 14.
[0030] If the core is to be supplied to the transformer manufacturer as a partial product, the lower holding frame 14 may already be assembled before separation, but in this case the lower holding frame 14 must be removed and reassembled in order to assemble the coil 13. [Explanation of symbols]
[0031] 1 Soft magnetic strip 2. Obi section 3 Band Coil 4 Multi-coil magazine 5 Winding mandrel 6 First Rotation Axis 7 Second Rotation Axis 8 First Band 9 Second Band 10 Covered nozzle 11 Separation plate piece 12 Separation device 13 Coil 14 Retaining frame elements
Claims
1. In an apparatus for manufacturing a strip ring core, a winding device (2) having two spaced apart winding mandrels (5) for winding the strip (1), said winding mandrels (5) being selectively rotatably drivable about a respective first rotation axis (6) or about a common second rotation axis (7), said winding mandrels (5) being movable perpendicularly to said rotation axes (6, 7) in order to adjust the spacing between said winding mandrels (5); two strip feeders each having at least one strip coil (3) for providing a soft magnetic strip (1); an insertion device having at least one manipulator for inserting a separation plate piece (11) into the formed strip (8, 9); at least one separating device (12) for cutting the strip (8, 9) to form a plurality of strip portions (2); An apparatus comprising:
2. 2. Apparatus according to claim 1, wherein the strip supplying device comprises at least two strip coils (3) for providing soft magnetic strips (1) of different widths, respectively.
3. 3. Apparatus according to claim 2, wherein the strip supplying devices each comprise a multi-coil magazine (4), in which at least two strip coils (3) are replaceably mountable.
4. 4. Apparatus according to any one of claims 1 to 3, comprising a strap tightening device for maintaining a predetermined strap tension.
5. 5. Apparatus according to any one of the preceding claims, comprising a coating device (10) for applying an insulating or connecting layer to the strip (1).
6. 6. Apparatus according to any one of claims 1 to 5, comprising a coil feeding device having a manipulator for receiving a coil (13) and transferring it onto the strip portion (2).
7. 7. Apparatus according to any one of claims 1 to 6, comprising a closing device having a manipulator for deforming the free ends of the strap portion (2) into a closed ring.
8. 8. The apparatus of claim 7, wherein the closure device comprises a manipulator that applies a cinching strap that encircles the entire magnetic core.
9. A method for manufacturing a band ring core, comprising the steps of: providing a soft magnetic strip (1) on at least two strip coils (3); unwinding the strip (1) from the two strip coils (3) and winding the strip (1) onto two spaced apart winding mandrels (5) by rotating the winding mandrels (5) about their respective first rotation axes (6) to form a first strip winding body (8) of multiple layers, while inserting a separating plate piece (11) into the first strip winding body (8) being formed after each of the multiple layers is formed; decreasing the spacing between the winding mandrels (5) until the first strips (8) come into contact with each other; unwinding the strip (1) from the two strip coils (3) and rotating the winding mandrel (5) about a common second axis of rotation (7) to form a multi-layered second strip winding (9) wound on the first strip winding (8), while inserting a separating plate piece (11) into the second strip winding (9) being formed after each of the multiple layers is formed; cutting the band (8, 9) stepwise to form a plurality of band portions (2); receiving at least one coil (13) and transferring the coil (13) onto the strip portion (2); deforming the free ends of the strap portion (2) and connecting the ends of the strap portion (2) to form a closed ring; The method comprising:
10. 10. The method according to claim 9, wherein for each winding mandrel (5), strips (1) of different widths are provided on at least two strip coils (3) respectively.
11. 11. The method according to claim 9 or 10, wherein an insulating or connecting layer is applied onto the strip (1) during unwinding and winding of the strip (1).
12. 12. A method according to any one of claims 9 to 11, comprising applying a cinching strap which surrounds the entire magnetic core.
13. 13. The method according to any one of claims 9 to 12, wherein the first strip winding (8) is formed on the winding mandrel (5) from at least two strips (1) of different widths, the width of which increases from the inside to the outside, and the second strip winding (9) is formed on the first strip winding (8) from at least two strips (1) of different widths, the width of which decreases from the inside to the outside.
14. 14. The method according to claim 13, wherein strips (1) of at least four different widths are used to form a magnetic core having at least eight stepped cross sections.