WO2023112561A1 - Magnetic member manufacturing method - Google Patents

Abstract

The present invention provides a magnetic member manufacturing method capable of achieving both demagnetization of a part of an electromagnetic steel plate and yield rate improvement based on effective use of the electromagnetic steel plate. A magnetic member manufacturing method according to the present invention comprises a reforming process for demagnetizing a predetermined region of an electromagnetic steel plate. The reforming process comprises a specific radiation process for scanning a high-energy beam along a specific trajectory (t) and radiating the high-energy beam to the electromagnetic steel plate (M). The specific trajectory passes through a planned removal region (101) and a planned remaining region (111), which are set adjacent to each other on the electromagnetic steel plate, and a start point (p0) and an end point (p1) are set within the same planned removal region. The present invention can separate both of a rotor core piece (1) and a stator core piece (2) by punching or the like from one electromagnetic steel plate subjected to the reforming process, for example.

Description

Method for manufacturing magnetic member

The present invention relates to a method for manufacturing a magnetic member made of an electromagnetic steel sheet, and the like.

A magnetic member used in an alternating magnetic field is often made of a laminate of electromagnetic steel sheets punched into a predetermined shape in order to form a magnetic circuit, suppress eddy current loss (iron loss), and ensure strength. Also, part of the laminate may be made non-magnetic from the viewpoint of high performance and low loss (efficiency). Descriptions related to such demagnetization are found in, for example, the following patent documents.

JP 2003-304670 JP 2011-6741

Patent Literature 1 proposes demagnetizing the bridge portion of a rotor core made of a laminate of magnetic steel sheets by diffusion and permeation treatment with a non-magnetic paint ([0018], [0019], [0022], etc.). . Patent Document 1 also proposes demagnetizing the bridge portion of the rotor core by introducing strain after laser welding ([0025], etc.).

In Patent Document 2, an electron beam is applied to a non-magnetizing ink applied to an electromagnetic steel sheet before or after punching (before lamination) to melt Fe in the electromagnetic steel sheet and Cr—Ni in the non-magnetizing ink. It is proposed to form local non-magnetic regions by alloying (austenitizing) ([0029]).

None of the patent documents, however, provide specific descriptions or suggestions about the irradiation paths (scanning trajectories) of laser beams and electron beams.

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a new method for manufacturing a magnetic member.

As a result of intensive research, the inventor conceived and realized a new path for the high-energy beam to be irradiated to demagnetize the magnetic steel sheet. By developing this, the present invention, which will be described later, has been completed.

<<Manufacturing method of magnetic member>>
(1) The present invention includes a modifying step of demagnetizing a predetermined region of an electromagnetic steel sheet, and the modifying step is a specific irradiation step of scanning a high-energy beam along a specific trajectory and irradiating the electromagnetic steel sheet. wherein the specific trajectory passes through a planned removal area and a planned remaining area set adjacently on the electromagnetic steel sheet, and the starting point and the end point are within the same planned removal area.

(2) According to the present invention, when the magnetic steel sheet is demagnetized, it is possible to effectively utilize the magnetic steel sheet by suppressing the area where the magnetic steel sheet is sacrificed (wastefully). In other words, it is possible to demagnetize a predetermined region of the magnetic steel sheet while improving the degree of freedom of shape for separating (punching, etc.) the magnetic steel sheet and the yield of the magnetic steel sheet.

This mechanism is considered as follows. In the case of demagnetizing a predetermined region (partially, even locally) of an electrical steel sheet by irradiating a high-energy beam (also simply referred to as a "beam"), the vicinity of the beam irradiation start position (starting point) tends to be insufficiently heated. . For example, when an electromagnetic steel sheet is melted by beam irradiation, an unmelted portion is likely to be formed near the starting point. On the other hand, thermal contraction tends to occur near the irradiation end position (end point) of the beam. For example, when an electromagnetic steel sheet is melted by beam irradiation, shrinkage cavities are likely to occur near the end point, and cracks are likely to occur near the shrinkage cavities. On the other hand, such a defective portion is usually less likely to occur midway between the start point and the end point of beam irradiation (an intermediate route connecting the start point and the end point).

In the present invention, the start and end points of the trajectory (path) of the beam that irradiates the electromagnetic steel sheet are concentrated in one planned removal area adjacent to the planned residual area (or part thereof) to be demagnetized. For this reason, defective portions that may be caused by beam irradiation are also concentrated in one scheduled removal area, and dispersion (scattering) on the electrical steel sheet is suppressed. As a result, it is possible to reduce the area of the magnetic steel sheet necessary for removing the defective portion, and to increase the degree of freedom in the shape of pieces that can be sorted from one magnetic steel sheet and to improve the yield of the magnetic steel sheet.

《Magnetic material》
The present invention can also be grasped as a magnetic member obtained by the manufacturing method described above. In addition, the "magnetic member" referred to in this specification may be an intermediate product or a final product. Intermediate products include, for example, electromagnetic steel sheets (materials, raw materials) that are partially demagnetized by beam irradiation, and further processes (e.g., separation process (punching, etc.), shaping process (flattening, trimming, etc.) , heat treatment, insulation, etc.). The final product is, for example, a laminate (e.g., core) in which the electromagnetic steel pieces separated after the modification process are laminated, and the laminate is subjected to another process or treatment, or other members (e.g., magnets, coils, etc.) It is an additional electromagnetic member (for example, a field element or an armature).

"others"
(1) “Modification” or “non-magnetization” as used herein means making the magnetic steel sheet (also referred to as “base material”) before modification difficult to be magnetized (making it difficult for magnetic flux to pass through ). For example, a decrease in (initial) magnetic permeability, a decrease in saturation magnetic flux density, an increase in magnetic resistance, etc. correspond to modification or demagnetization. A ferromagnetic material, which is the base material of an electrical steel sheet, usually changes in composition and structure by modification or demagnetization, and becomes either a diamagnetic material, a paramagnetic material, or an antiferromagnetic material. A typical demagnetization is austenitization of ferrite phase and martensite phase.

(2) The "trajectory" of the beam as used herein is determined based on the path of the beam center. Unless otherwise specified, it suffices to use the macroscopic path as the beam trajectory instead of the microscopic path. Also, the "start point" and "end point" of the trajectory are preferably set within the planned removal area in consideration of not only the beam diameter but also the heat-affected area due to beam irradiation.

(3) Unless otherwise specified, "x to y" as used herein includes the lower limit value x and the upper limit value y. A new range such as “a to b” can be established as a new lower or upper limit of any numerical value included in the various numerical values or numerical ranges described herein. In addition, unless otherwise specified, "x to y mm" as used herein means x mm to y mm. The same applies to other unit systems.

FIG. 4 is a conceptual diagram showing an example of division of an electromagnetic steel sheet; It is an enlarged view of a part of it. It is a schematic diagram which shows the Example of a modification process. It is a photograph showing an experimental example based on the example. It is a schematic diagram which shows the 1st comparative example of a property modification process. It is a photograph showing an experimental example based on the first comparative example. It is a schematic diagram which shows the 2nd comparative example of a property modification process. It is a photograph showing an experimental example based on the second comparative example. It is a schematic diagram which shows an example of the specific locus|trajectory of a laser. FIG. 11 is a schematic diagram showing another example of the specific trajectory of the laser; FIG. 4 is a schematic diagram illustrating a non-magnetic portion provided in the bridge area of the rotor core; It is a schematic diagram which illustrates the scanning locus|trajectory of the laser irradiated to the bridge|bridging area.

One or more components arbitrarily selected from the matters described in this specification can be added to the configuration of the present invention described above. A component related to a method can also be a component related to an object (such as a magnetic member). Which embodiment is the best depends on the target, required performance, and the like.

《Electromagnetic Steel Sheet》
The electrical steel sheet may have any specific magnetic properties (magnetic permeability, saturation magnetization, etc.), composition, structure, thickness, shape, and the like. A typical electrical steel sheet, for example, has a bcc crystal structure (ferrite phase) and is made of silicon steel (for example, an iron alloy containing 1 to 5% by mass of Si). Its thickness is, for example, 0.1-1.0 mm or even 0.2-0.7 mm. If the thickness is too thin, the number of laminated layers increases (increase in cost), the strength of the non-magnetic portion decreases, and the beam irradiation conditions become narrower. If it is too thick, it causes an increase in iron loss, an increase in strain due to the reforming process, and the like.

The magnetic steel sheet may be a oriented magnetic steel sheet or a non-oriented magnetic steel sheet. Non-oriented electrical steel sheets are used for electric motors (including generators/simply referred to as “motors”), for example. At least one surface of an electrical steel sheet is usually coated with an insulation. However, when insulating coating (insulating film formation) is performed after the modifying process, the insulating coating before the modifying process is not necessarily essential.

《Modification process》
(1) In the modifying step, a predetermined region of the electrical steel sheet is demagnetized by beam irradiation. Non-magnetization includes, for example, austenitization or transformation that changes from a bcc structure (α phase) to an fcc structure (γ phase), alloying of the base material of an electrical steel sheet with a γ phase stabilizing element, and the like. It occurs when the composition, etc., changes.

A representative example of the modification process is alloying, in which a modifying material (agent) applied to an electromagnetic steel sheet and an electromagnetic steel sheet (silicon steel, etc.) are heated and melted (mixed and stirred) by beam irradiation, and then cooled and solidified. . Further, the reforming process may be performed not only by melting and solidification, but also by composition change or structure change by ablation. The modifier may be applied by controlling the atmosphere of the beam irradiation area.

(2) The specific irradiation step is performed by scanning the beam along a specific trajectory. As long as the specific trajectory passes through at least a part of the planned residual area (planned reforming section) and the starting point and the end point are within the planned removal area adjacent to the planned residual area, the specific route does not matter.

The start point and end point are determined within a series of ranges (single stroke range) where the beam is continuously irradiated. A plurality of specific trajectories (a plurality of sets of start points and end points) may be set for one region to be demagnetized. At that time, each pair of the start point and the end point may be within the same planned removal area or within different planned removal areas.

(3) The high-energy beam is, for example, a laser or an electron beam with a high energy density (fluence). The type (amplification medium, excitation source, optical resonator, etc.), output, energy density, irradiation area, overlap ratio, etc. of the laser are appropriately selected and adjusted. The laser may be a continuous wave laser or a pulsed laser. As an example of lasers, there is a fiber laser (a type of solid-state laser) using an optical fiber (for example, a double-clad fiber whose core is doped with a rare earth element) as an amplification medium. A fiber laser uses, for example, a semiconductor laser (LD) as an excitation source, and includes an incident-side light reflection mirror and an output-side low-reflection mirror as an optical resonator.

(4) Modifiers added to the electromagnetic steel sheet include, for example, powder, ink (paste, slurry), sheet (film), and the like. The powder is applied, for example, by scraping or the like onto a predetermined region of the magnetic steel sheet to be demagnetized. The scraping is performed using a dent (recess) formed on the electromagnetic steel sheet corresponding to a predetermined region, a formwork placed on the electromagnetic steel sheet, or the like. Ink (slurry) is applied onto a predetermined area by, for example, screen printing, inkjet printing, or the like. The sheet (film) is, for example, preliminarily molded (die-cut, etc.) into a desired shape and adhered onto a predetermined area.

《Other processes》
(1) When the beam irradiation mark (hereinafter referred to as “bead”) rises from the base surface (non-modified surface) of the electromagnetic steel sheet, it is below the base surface of the electromagnetic steel sheet (even in a flat state, it is further depressed). state is acceptable.). The shaping process may be performed immediately after the modification process, or may be performed together with the lamination process described below. The shaping step may also serve to remove thermal distortion or the like of the electromagnetic steel sheet due to beam irradiation.

(2) When the vicinity of the surface irradiated with the beam is in a non-insulated state, an insulating treatment step may be performed. The insulating treatment process is performed by, for example, insulating resin coating, chemical conversion treatment (for example, phosphate treatment), and the like. Further, the insulating treatment step may be a processing step of forming an insulating space between the facing surfaces during lamination. The processing step may also serve as the shaping step described above.

(3) By dividing (dividing) the electromagnetic steel sheet after the reforming process, an electromagnetic steel piece having a desired shape is obtained (separation process). The separation step is performed by, for example, press working (punching), laser working, or the like. The separation process and the above-described shaping process and/or insulation treatment process may be performed in any order. After the separation step, further trimming, finishing treatment, and the like may be performed. During the separation step, it is preferable to remove the area to be removed including the start point and end point of laser irradiation.

(4) The electromagnetic steel pieces partially demagnetized are stacked to form a laminate (lamination step). The fixing of the plurality of electromagnetic steel pieces is performed by caulking by press work or the like, welding, or the like. The laminate may be further subjected to a finishing process or the like to ensure dimensional accuracy.

<<Application example>>
Magnetic members include, for example, rotor core pieces and stator core pieces of electric motors (including generators), and laminates thereof (rotor cores and stator cores).

When separating the rotor core pieces and the stator core pieces from one electromagnetic steel sheet, for example, the slot area of the rotor core piece is the planned removal area, and the peripheral end area of the rotor core piece adjacent to the stator core piece is the planned remaining area. In the case of the inner rotor piece, the outer peripheral end region is the planned remaining region, and in the case of the outer rotor piece, the inner peripheral end region is the planned residual region.

The non-magnetic portion formed in the peripheral end region may have any form (shape, width, etc.), arrangement, etc., as long as it can prevent a closed loop of magnetic lines of force (short circuit of magnetic lines of force). For example, the non-magnetic portion may penetrate the bridge area (peripheral edge area), which is the frame side of the slot (magnet hole), in at least one location in the substantially radial direction.

The present invention will be specifically described while exemplifying a case where rotor core pieces and stator core pieces used for manufacturing a motor core (laminate) are separated from a single electromagnetic steel plate.

"overview"
As shown in FIG. 1A, consider a case in which a single electromagnetic steel plate M is punched into rotor core pieces 1 and stator core pieces 2 . The rotor core piece 1 and the stator core piece 2 are used to manufacture a rotor core (laminate/not shown) and a stator core (laminate/not shown) of an embedded magnet type synchronous machine (referred to as "IPM motor"). For convenience of explanation, each part of the electromagnetic steel sheet M before punching (virtual part indicated by a two-dot chain line) and each part of the electromagnetic steel sheet M after punching (a real part indicated by a solid line) are denoted by the same reference numerals in each figure. bottom.

As shown in FIG. 1B, which is an enlarged view of part A of FIG. 1A, the rotor core piece 1 is for eight magnetic poles. The formation of bridges 111, 112 on the end sides is planned. The slots 101 and 102 (slot areas) and the shaft hole 10 before punching correspond to areas to be removed, and the bridges 111 and 112 (bridge areas) correspond to areas to remain.

The stator core piece 2 is for 48 poles, and it is planned to form comb- like teeth 211, 212 and slots 201, 202, 203 on both sides thereof for each pole. The slots 201, 202, 203 (slot areas) before punching correspond to areas to be removed, and the teeth 211, 212 (teeth areas) and the yoke 21 correspond to areas to remain. For the sake of convenience, the description of each part of the rotor core piece 1 and the stator core piece 2 is given by appropriately extracting only a typical part, and the description of other parts repeatedly appearing in the circumferential direction is omitted.

By the way, the annular gap c formed between the rotor core piece 1 and the stator core piece 2 punched out of one electromagnetic steel plate M is reflected in the air gap of the IPM motor. Since the air gap affects the performance of the motor, it is preferable that c is, for example, about 0.2 to 1 mm, or even 0.3 to 0.7 mm.

《Modification process》
(1) FIG. 2A shows an outline of a modification step of demagnetizing a part of the regions to be the bridges 111 and 112 of the electromagnetic steel sheet M before punching. First, modifying material layers 311 and 312 are provided in the planned area and its periphery (step I). The modifying material layers 311 and 312 are made of, for example, Cr—Ni alloy powder, and are formed by scraping or coating.

Next, laser irradiation is performed from above the modifying material layers 311 and 312 . Laser irradiation scans the center of the laser beam along a trajectory t (specific trajectory) that has a start point p0 and an end point p1 in the planned areas that will become the slots 101 and 102 and that passes through the planned areas that will become the bridges 111 and 112 ( process II/specific irradiation process). As a result, a bead b (laser irradiation mark/non-magnetic portion) is formed in the laser irradiation area by melting, mixing, cooling and solidifying the magnetic steel sheet M and the modifier layers 311 and 312 .

Here, the trajectory t of the laser irradiation is set so that at least one bead b penetrating the bridges 111 and 112 in a substantially radial direction is formed. Further, the trajectory t is set so that the bead b formed on the bridges 111 and 112 does not reach the stator core piece 2 side beyond the clearance c at the time of punching. Note that the laser irradiation may be performed from both sides of the magnetic steel sheet M (front side and back side). However, even if the laser irradiation is performed only from one side of the magnetic steel sheet M, a bead extending from one side to the other side of the magnetic steel sheet M (bead penetrating in the thickness direction) can be formed.

After that, the electromagnetic steel sheet M from which the excess modifier layers 311 and 312 have been removed is stamped with a die having a predetermined shape (step III). As a result, the rotor core piece 1 having the non-magnetic portions 121 and 122 in part of the bridges 111 and 112 is obtained together with the stator core piece 2 . Defective portions (unmelted portions, shrinkage cavities, etc.) formed at the start point p0 and the end point p1 of laser irradiation during the punching process are removed together with the formation of the slots 101 and 102 .

(2) FIG. 2B shows an experimental example in which the electromagnetic steel sheet to which the modifier was added was irradiated with the laser along the locus t described above. 50HXT780T (thickness: 0.5 mm) manufactured by Nippon Steel Corporation was used as the electromagnetic steel sheet. A Cr-50% by mass Ni alloy powder (well powder manufactured by Nippon Welding Rod Co., Ltd.) was used as the modifier. Addition of the modifier to the magnetic steel sheet was carried out by scraping the powder on a thin plate (thickness: 0.4 mm) placed on the magnetic steel sheet. Laser irradiation is performed using a single-type fiber laser (laser transmitter: YLS-2000-SM manufactured by IPG Co., Ltd., fiber core diameter: 24 μm, optical system: 3D galvanometer scanner manufactured by Yaskawa Electric Corporation, converging diameter: 36 μm). 340 W, 11 mm/s, amplitude width 0.6 mm, Ar flow conditions.

Although the trajectory t shown in FIG. 2B is a substantially U-shaped path for the sake of convenience, it is actually a substantially linear reciprocating path of about 4 mm. One graduation (minimum graduation) of the scale shown in FIG. 2B is 0.5 mm.

As can be seen from FIG. 2B, an unmelted portion was formed near the laser irradiation start point p0, and a shrinkage cavity was formed near the end point p1. More specifically, the position where the shrinkage cavities occur was slightly closer to the end point p1 (upper side in FIG. 2B).

The bead (non-magnetic portion) formed in the intermediate path between the start point p0 and the end point p1 was good. From this experimental example, it was confirmed that, for example, a good bead portion can be left as the non-magnetic portion 121 of the bridge 111 while removing the defective portion (unmelted portion, shrinkage cavity) of the bead at the time of forming the slot 101. . It was also confirmed that the edge of the bead can be accommodated within the gap c so as to prevent it from crossing over to the stator core piece 2 side.

<<Comparative example>>
(1) As a first comparative example, a case where laser irradiation is performed along a locus t shown in FIG. 3A is shown. An experimental example is shown in FIG. 3B. The locus t shown in FIG. 3B is a substantially straight path of approximately 10 mm. For the sake of convenience, the members and parts already described are given the same reference numerals, and detailed descriptions thereof are omitted (the same applies hereinafter). Also, the magnetic steel sheets and laser irradiation conditions used in the experiment are the same as those described above with regard to the experimental example shown in FIG. 2B (the same applies hereinafter).

The trajectory t shown in FIG. 3A has a starting point p0 in the expected areas of the slots 101 and 102, passes through the expected areas of the bridges 111 and 112, and has an end point p1 on the outer peripheral side thereof. In this case, the defect portion (shrinkage cavity) formed slightly before the end point p1 does not fit within the gap c and extends to a region that can become the stator core piece 2 . Considering the removal of such defective portions, it can be seen that the rotor core pieces 1 and the stator core pieces 2 cannot be separated from one electromagnetic steel plate M at the same time.

(2) As a second comparative example, a case where laser irradiation is performed along a locus t shown in FIG. 4A is shown. An experimental example is shown in FIG. 4B. In this comparative example, the rotor core pieces 1 punched out from the electromagnetic steel sheet M in advance were irradiated with a laser to modify (demagnetize) the bridges 111 and 112 . The locus t of laser irradiation was the same as in the example (see FIG. 2A).

In the case of this comparative example, defective portions (unmelted portions, shrinkage cavities, etc.) formed at the start point p0 and the end point p1 of laser irradiation are removed by forming slots 101 and 102 . However, the narrow bridges 111 and 112 on the outer peripheral end side of the rotor core piece 1 were damaged due to shrinkage cavities and the like caused by the laser irradiation.

"Trajectory"
(1) As long as a predetermined region can be demagnetized and a desired magnetic steel piece can be obtained with a high yield from the magnetic steel sheet after the reforming process, various trajectories for scanning the beam are possible. For example, the substantially U-shaped trajectory t shown in FIG. 2A may be replaced with a substantially square-shaped (substantially U-shaped) trajectory t1 shown in FIG. The trajectory t2 may be used.

It should be noted that the trajectory referred to in this embodiment and in this specification is a schematic main path drawn by the center of the beam on the electromagnetic steel sheet, unless otherwise specified. When viewed in detail, the beam center may, for example, follow minor paths that intersect or oscillate with respect to the main path. As a specific example, there is a trajectory that traces a zigzag secondary path ts from a microscopic point of view, while following a linear main path tm from a macroscopic point of view (see FIG. 6B).

(2) As shown in FIG. 6A, the slot 101 of the rotor core piece 1 is composed of slots 1011 and 1012 that are divided into left and right sides, for example. At this time, non-magnetic portions 1211 and 1212 are formed on the bridges 1111 and 1112 in the outer peripheral end regions of the slots 1011 and 1012 by the above-described modification process.

By the way, it is preferable that the non-magnetic portion 1213 is also formed in the bridge 1113 formed between the slots 1011 and 1012 (non-peripheral end region). The non-magnetic portion 1213 may be formed by laser irradiation along a linear trajectory (main path tm) shown in FIG. 6B. The trajectory may include a subpath ts that is microscopically zigzag.

Of course, the non-magnetic portion 1213 may be formed in the same manner as the non-magnetic portions 1211 and 1212 (see FIGS. 2A and 2B). That is, the non-magnetic portion 1213 may be formed by scanning the laser along a trajectory having the start point p0 and the end point p1 in one of the slots 1011 or 1012 (area to be removed) (specific irradiation step).

Furthermore, the non-magnetic portion 1213 may be formed along a plurality of specific trajectories. For example, the laser is scanned along a first trajectory having a start point p0 and an end point p1 in the slot 1011 (area to be removed) and a second trajectory having a start point p0 and an end point p1 in the slot 1012 (area to be removed) ( specific irradiation step), the non-magnetic portion 1213 may be formed. This point also applies to the non-magnetic portions 121 (1211, 1212). For example, a first locus having a start point p0 and an end point p1 in the slot 101 (area to be removed) and a second locus having a start point p0 and an end point p1 in the slot 202 (area to be removed/see FIG. 1B) on the stator core piece 2 side. The non-magnetic portion 121 may be formed by scanning the laser along (specific irradiation step).

t trajectory p0 start point p1 end point M electromagnetic steel sheet 1 rotor core piece 2 stator core piece 101 slot 111 bridge 121 non-magnetic portion 311 modifier layer

Claims (6)

1. Equipped with a modification step of demagnetizing a predetermined region of the electromagnetic steel sheet,
   The modifying step includes a specific irradiation step of scanning a high-energy beam along a specific trajectory and irradiating the electromagnetic steel sheet,
   A method of manufacturing a magnetic member, wherein the specific trajectory passes through a planned removal area and a planned remaining area set adjacently on the electromagnetic steel sheet, and has a starting point and an end point within the same planned removal area.
2. The method for manufacturing a magnetic member according to claim 1, wherein the specific irradiation step is a step of melting at least part of the expected remaining area.
3. The magnetic member manufacturing method according to claim 1 or 2, wherein the magnetic steel sheet is scheduled to be divided into rotor core pieces and stator core pieces from one sheet after the reforming process.
4. The method of manufacturing a magnetic member according to claim 3, wherein the expected remaining area is a peripheral end area of the rotor core piece adjacent to the stator core piece.
5. 5. The method of manufacturing a magnetic member according to claim 4, wherein the modifying step forms a non-magnetic portion penetrating in a substantially radial direction in at least a part of the peripheral end region.
6. The method for manufacturing a magnetic member according to any one of claims 3 to 5, wherein the areas to be removed are slot areas of the rotor core pieces.

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