Manufacturing method of magnetic member

Abstract

To provide a manufacturing method of a magnetic member capable of achieving both nonmagnetization of a portion of an electrical steel and yield improvement caused by efficient utilization of the electrical steel.SOLUTION: A manufacturing method of a magnetic member of the invention includes a modification step for nonmagnetizing a prescribed area of an electrical steel. The modification step includes a specific irradiation step for scanning a high energy beam along a specific trajectory (t) to irradiate it to the electrical steel (M). The specific trajectory passes through a removal predetermined region (101) and a scheduled left region (111) set adjacently on the electrical steel, and a starting point (p0) and an end point (p1) are in the same removal predetermined region. According to the invention, for example, both rotor core piece (1) and rotor core piece (2) can be separated from one electrical steel after the modification step by punching or the like.SELECTED DRAWING: Figure 2A

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a magnetic member made of an electromagnetic steel sheet. [Background technology]

[0002] Magnetic members used in alternating magnetic fields are often made of laminates of electromagnetic steel sheets punched into a predetermined shape to form magnetic circuits, suppress eddy current loss (iron loss), ensure strength, etc. In addition, a portion of the laminate may be made non-magnetic from the viewpoint of improving performance and reducing loss (efficiency). Descriptions related to such non-magnetic properties can be found, for example, in the following patent documents: [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2003-304670 [Patent Document 2] Patent Publication No. 2011-6741 Summary of the Invention [Problem to be solved by the invention]

[0004] Patent Document 1 proposes demagnetizing the bridge portion of a rotor core made of laminated electromagnetic steel sheets by a diffusion and penetration treatment of 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.).

[0005] Patent document 2 proposes forming localized non-magnetic regions by irradiating an electron beam onto a demagnetizing ink applied to an electromagnetic steel sheet (before lamination) before or after punching, thereby melting and alloying (austenitizing) the Fe in the electromagnetic steel sheet and the Cr-Ni in the demagnetizing ink (

[0029] ).

[0006] However, none of the patent documents provides any specific description or suggestion regarding the irradiation path (scanning trajectory) of the laser beam or electron beam.

[0007] The present invention has been made in view of the above circumstances, and has as its object to provide a new method for manufacturing a magnetic member. [Means for solving the problem]

[0008] As a result of extensive research, the inventors of the present invention came up with the idea of ​​a new path for the high-energy beam to be irradiated to render electrical steel sheets non-magnetic, and have since developed this idea to complete the present invention, which will be described below.

[0009] <<Method for manufacturing magnetic member>> (1) The present invention is a method for manufacturing a magnetic component, comprising a modification process for demagnetizing a predetermined region of an electromagnetic steel sheet, the modification process including a specific irradiation process for scanning a high-energy beam along a specific trajectory and irradiating the electromagnetic steel sheet with the beam, the specific trajectory passing through a planned removal area and a planned remaining area that are set adjacent to each other on the electromagnetic steel sheet, and the start point and end point of the specific trajectory being within the same planned removal area.

[0010] (2) According to the present invention, when demagnetizing an electromagnetic steel sheet, it is possible to effectively utilize the electromagnetic steel sheet by suppressing regions where the electromagnetic steel sheet is sacrificed (wasted). In other words, it is possible to demagnetize predetermined regions of the electromagnetic steel sheet while improving the degree of freedom in shape when separating (punching, etc.) the electromagnetic steel sheet and the yield of the electromagnetic steel sheet.

[0011] The mechanism behind this is thought to be as follows: When a predetermined region (partial, or even localized area) of an electromagnetic steel sheet is demagnetized by irradiation with a high-energy beam (also simply referred to as "beam"), the vicinity of the start position (start point) of the beam irradiation is likely to be insufficiently heated. For example, if an electromagnetic steel sheet is melted by beam irradiation, an unmelted area is likely to form near the start point. On the other hand, thermal contraction is likely to occur near the end position (end point) of the beam irradiation. For example, if an electromagnetic steel sheet is melted by beam irradiation, shrinkage cavities are likely to form near the end point, and further, cracks are likely to form near the shrinkage cavities. On the other hand, such defects are usually unlikely to form midway between the start and end points of the beam irradiation (on the path connecting the start and end points).

[0012] In the present invention, the start and end points of the trajectory (path) of the beam irradiated onto the electromagnetic steel sheet are concentrated in a single removal zone adjacent to the intended remaining zone (or part thereof) to be demagnetized. Therefore, defects that may be generated by beam irradiation are also concentrated in a single removal zone, and dispersion (scattering) of defects on the electromagnetic steel sheet is suppressed. As a result, the area of ​​the electromagnetic steel sheet required for defect removal can be reduced, which increases the degree of freedom in the shape of the pieces that can be cut from a single electromagnetic steel sheet and improves the yield of the electromagnetic steel sheet.

[0013] <Magnetic member> The present invention can also be understood as a magnetic member obtained by the above-described manufacturing method. Note that the "magnetic member" referred to in this specification may be either an intermediate product or a final product. An intermediate product is, for example, an intermediate material obtained by irradiating a portion of an electromagnetic steel sheet (raw material, raw material) with a beam to demagnetize it, or a work-in-progress that has undergone further processes (for example, a separation process (punching, etc.), a shaping process (flattening, trimming, etc.), heat treatment, insulation treatment, etc.). A final product is, for example, a laminate (for example, a core) obtained by stacking electromagnetic steel pieces separated after the modification process, or an electromagnetic member (for example, a field magnet or an armature) obtained by subjecting the laminate to another process or treatment or by adding other components (for example, a magnet, a coil, etc.) to the laminate.

[0014] "others" (1) In this specification, "modification" or "demagnetization" means making the electrical steel sheet (also referred to as the "base material") less magnetizable (making it more difficult for magnetic flux to pass through) before modification. 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. The ferromagnetic material that is the base material of electrical steel sheet usually undergoes a change in composition and structure through modification or demagnetization, becoming either a diamagnetic material, a paramagnetic material, or an antiferromagnetic material. A typical example of demagnetization is the austenitization of a ferrite phase or a martensite phase.

[0015] (2) The "trajectory" of the beam in this specification is determined based on the path of the beam center. Unless otherwise specified, it is sufficient to refer to the macroscopic path as the trajectory of the beam, not the microscopic path. Furthermore, the "starting point" and "ending point" of the trajectory should be set within the area to be removed, taking into consideration not only the beam diameter but also the heat-affected area associated with beam irradiation.

[0016] (3) Unless otherwise specified, "x to y" in this specification includes a lower limit value x and an upper limit value y. Any numerical value included in the various numerical values ​​or numerical ranges described in this specification may be used as a new lower limit or upper limit value to create a new range such as "a to b." Furthermore, unless otherwise specified, "x to y mm" in this specification means x mm to y mm. The same applies to other unit systems. [Brief explanation of the drawings]

[0017] [Figure 1A] FIG. 10 is a hypothetical diagram showing an example of division of an electromagnetic steel sheet. [Figure 1B] FIG. [Figure 2A] 1A to 1C are schematic diagrams showing an example of a modification step. [Figure 2B] 10 is a photograph showing an experimental example based on the embodiment. [Figure 3A] FIG. 10 is a schematic diagram showing a first comparative example of the modification step. [Figure 3B] 10 is a photograph showing an experimental example based on the first comparative example. [Figure 4A] FIG. 10 is a schematic diagram showing a second comparative example of the modification step. [Figure 4B] 10 is a photograph showing an experimental example based on the second comparative example. [Figure 5A] FIG. 2 is a schematic diagram showing an example of a specific trajectory of a laser beam. [Figure 5B] FIG. 10 is a schematic diagram showing another example of a specific trajectory of a laser beam. [Figure 6A] 3A and 3B are schematic diagrams illustrating non-magnetic portions provided in bridge regions of a rotor core. [Figure 6B] 10 is a schematic diagram illustrating a scanning trajectory of a laser irradiated onto the bridge region. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0018] One or more components arbitrarily selected from the items described in this specification may be added to the above-described configuration of the present invention. Components related to the method may also be components related to the object (magnetic member, etc.). Which embodiment is best depends on the target, required performance, etc.

[0019] 《Electromagnetic steel sheet》 The magnetic steel sheet may have any specific magnetic properties (such as magnetic permeability and saturation magnetization), composition, structure, thickness, shape, etc. Typical magnetic steel sheets have a bcc crystal structure (ferrite phase) and are made of silicon steel (for example, an iron alloy containing 1 to 5 mass % of Si). The thickness is, for example, 0.1 to 1.0 mm, or even 0.2 to 0.7 mm. If the sheet is too thin, it will require an increased number of laminations (increased costs), reduce the strength of the non-magnetic parts, and narrow the beam irradiation conditions. If the sheet is too thick, it will increase iron loss and increase distortion due to the modification process.

[0020] The electrical steel sheet may be either a directional electrical steel sheet or a non-directional electrical steel sheet. For example, a non-directional electrical steel sheet is used for an electric motor (including a generator / simply referred to as a "motor"). The electrical steel sheet is usually insulated on at least one surface. However, if an insulating coating (insulating film formation) is applied after the modification process, the insulating coating before the modification process is not necessarily required.

[0021] <<Modification process>> (1) The modification process involves demagnetizing a specific region of the electrical steel sheet by beam irradiation. Demagnetization occurs through changes in the structure and composition of the specific region, such as austenitization or transformation from a bcc structure (α phase) to an fcc structure (γ phase), or alloying of the base material of the electrical steel sheet with a γ-phase stabilizing element.

[0022] A typical example of a modification process is alloying, in which a modifier (agent) applied to an electromagnetic steel sheet and the electromagnetic steel sheet (silicon steel, etc.) are heated and melted (mixed and stirred) by beam irradiation, followed by cooling and solidification. In addition to melting and solidification, the modification process may also be carried out by ablation to change the composition or structure. The application of the modifier may also be achieved by controlling the atmosphere in the beam irradiation area.

[0023] (2) The specific irradiation step is performed by scanning the beam along a specific trajectory. The specific trajectory can be any specific path as long as it passes through at least a portion of the intended remaining area (the intended modification portion) and the start and end points are within the intended removal area adjacent to the intended remaining area.

[0024] The start and end points are determined within a continuous range (a range drawn in one stroke) that is continuously irradiated with the beam. Multiple specific trajectories (multiple pairs of start and end points) may be set for one region to be demagnetized. In this case, each pair of start and end points may be within the same region to be removed, or may be within different regions to be removed.

[0025] (3) The high-energy beam is, for example, a laser or electron beam with a high energy density (fluence). The type (amplification medium, excitation source, optical resonator, etc.), output, energy density, irradiation area, overlap rate, etc. of the laser are appropriately selected and adjusted. The laser may be a continuous wave laser or a pulsed laser. One example of a laser is a fiber laser (a type of solid-state laser) that uses an optical fiber (for example, a double-clad fiber with a rare earth element doped in the core) as the amplification medium. A fiber laser, for example, uses a semiconductor laser (LD) as the excitation source and includes an optical reflection mirror on the input side and a low-reflection mirror on the output side as an optical resonator.

[0026] (4) Examples of modifiers applied to the electromagnetic steel sheet include powder, ink (paste, slurry), and sheet (film). Powder is applied, for example, by leveling or the like to a predetermined area of ​​the electromagnetic steel sheet to be demagnetized. Leveling is performed by using a depression (recess) formed on the electromagnetic steel sheet corresponding to the predetermined area, or by using a form placed on the electromagnetic steel sheet. Ink (slurry) is applied to the predetermined area by, for example, screen printing, inkjet printing, or the like. Sheets (films) are, for example, formed (die-cut, etc.) into a desired shape in advance and then attached to the predetermined area.

[0027] 《Other processes》 (1) When the irradiation marks of the beam (referred to as "beads" as appropriate) protrude from the base surface (unmodified surface) of the electromagnetic steel sheet, a shaping process may be carried out to make the bead below the base surface of the electromagnetic steel sheet (which may be flat or recessed). The shaping process may be carried out immediately after the modification process, or may be carried out in conjunction with the lamination process described below. The shaping process may also serve to remove thermal distortion, etc. of the electromagnetic steel sheet caused by beam irradiation.

[0028] (2) When the area near the surface irradiated with the beam becomes non-insulating, an insulating treatment process may be performed. The insulating treatment process may be performed by, for example, applying an insulating resin or chemical conversion treatment (e.g., phosphate treatment). The insulating treatment process may also be a processing process for forming an insulating space between opposing layers when stacked. The processing process may also serve as the shaping process described above.

[0029] (3) After the modification process, the electromagnetic steel sheet is divided (sliced) to obtain electromagnetic steel pieces of the desired shape (separation process). The separation process is performed, for example, by press processing (punching), laser processing, etc. The separation process may be performed before or after the above-mentioned shaping process and / or insulation process. After the separation process, further trimming, finishing processes, etc. may be performed. During the separation process, it is preferable to also remove the planned removal area including the start and end points of the laser irradiation.

[0030] (4) The partially demagnetized electromagnetic steel pieces are stacked to form a laminate (stacking process). The plurality of electromagnetic steel pieces are fixed together by crimping using a press or by welding. The laminate may further be subjected to finishing processes to ensure dimensional accuracy.

[0031] 《Application examples》 Examples of magnetic members include rotor core pieces and stator core pieces of an electric motor (including a generator), or laminates thereof (rotor cores and stator cores).

[0032] When rotor core pieces and stator core pieces are separated from one electromagnetic steel sheet, for example, the slot regions of the rotor core pieces are the areas to be removed, and the peripheral edge regions of the rotor core pieces that are close to the stator core pieces are the areas to be left. Note that the outer peripheral edge region is the area to be left for inner rotor pieces, and the inner peripheral edge region is the area to be left for outer rotor pieces.

[0033] The non-magnetic portion formed in the peripheral edge region may have any form (shape, width, etc.) or arrangement, etc., as long as it can prevent a closed loop of magnetic field lines (short circuit of magnetic field lines). For example, the non-magnetic portion may penetrate the bridge region (peripheral edge region), which forms the frame side of the slot (magnet hole), in at least one location in a substantially radial direction. [Example]

[0034] The present invention will be specifically described using as an example a case where rotor core pieces and stator core pieces used in manufacturing a motor core (lamination body) are cut out from a single electromagnetic steel sheet.

[0035] "overview" As shown in Fig. 1A, consider the case where rotor core laminations 1 and stator core laminations 2 are punched out from a single electromagnetic steel sheet M. The rotor core laminations 1 and stator core laminations 2 are used to manufacture a rotor core (laminations / not shown) and a stator core (laminations / not shown) of an interior permanent magnet synchronous machine (referred to as an "IPM motor"). For ease of explanation, the same reference numerals are used in each drawing to designate parts of the electromagnetic steel sheet M before punching (imaginary parts shown by two-dot chain lines) and parts of the electromagnetic steel sheet M after punching (actual parts shown by solid lines).

[0036] As shown in Fig. 1B, which is an enlarged view of part A in Fig. 1A, rotor core piece 1 is for eight magnetic poles, and for each magnetic pole, approximately U-shaped slots 101, 102 for integrally molding bonded magnets are planned to be formed, with bridges 111, 112 planned to be formed on the outer peripheral edge sides of these slots. The slots 101, 102 (slot areas) and shaft hole 10 before punching correspond to the areas to be removed, and the bridges 111, 112 (bridge areas) correspond to the areas to be left.

[0037] The stator core pieces 2 are for 48 poles, and for each pole, comb-tooth-shaped teeth 211, 212 and slots 201, 202, 203 on either side thereof are planned to be formed. The slots 201, 202, 203 (slot areas) before punching correspond to areas to be removed, while the teeth 211, 212 (teeth areas) and the yoke 21 correspond to areas to be left. For convenience, the explanation of each part of the rotor core pieces 1 and stator core pieces 2 will be given by appropriately extracting representative parts, and explanation of other parts that appear repeatedly in the circumferential direction will be omitted.

[0038] Incidentally, the annular gap c formed between the rotor core pieces 1 and stator core pieces 2 punched out from a single electromagnetic steel sheet M is reflected in the air gap of the IPM motor. Because the air gap affects motor performance, it is preferable that c be set to, for example, 0.2 to 1 mm, or even 0.3 to 0.7 mm.

[0039] <<Modification process>> (1) An overview of the modification process for demagnetizing a portion of the regions that will become the bridges 111, 112 in the magnetic steel sheet M before punching is shown in Figure 2A. First, modifier layers 311, 312 are provided in and around the regions that will become the bridges 111, 112 (Step I). The modifier layers 311, 312 are made of, for example, Cr-Ni alloy powder and are formed by scraping or coating.

[0040] Next, laser irradiation is performed from above the modifier layers 311, 312. The laser irradiation has a start point p0 and an end point p1 in the areas expected to become the slots 101, 102, and the center of the laser beam is scanned along a trajectory t (specific trajectory) that passes through the areas expected to become the bridges 111, 112 (step II / specific irradiation step). As a result, beads b (laser irradiation marks / non-magnetic portions) are formed in the laser irradiation areas by melting and mixing the electromagnetic steel sheet M and the modifier layers 311, 312 and cooling and solidifying them.

[0041] Here, the trajectory t of the laser irradiation is set so as to create at least one bead b that penetrates the bridges 111, 112 in a substantially radial direction. Furthermore, the trajectory t is set so that the bead b formed on the bridges 111, 112 does not extend beyond the gap c created during punching onto the stator core piece 2 side. Note that the laser irradiation may be performed from both sides (the front and back sides) of the electromagnetic steel sheet M. However, even if the laser is only irradiated from one side of the electromagnetic steel sheet M, a bead that reaches from one side to the other side of the electromagnetic steel sheet M (a bead that penetrates in the thickness direction) can be formed.

[0042] Thereafter, the electromagnetic steel sheet M from which the excess modifier layers 311, 312 have been removed is punched using a die of a predetermined shape (step III). As a result, rotor core pieces 1 having nonmagnetic portions 121, 122 in parts of the bridges 111, 112 are obtained together with stator core pieces 2. During punching, defects (unmelted portions, shrinkage cavities, etc.) formed at the start point p0 and end point p1 of the laser irradiation are removed as the slots 101, 102 are formed.

[0043] (2) Figure 2B shows an example of an experiment in which laser irradiation along the trajectory t described above was performed on an electrical steel sheet with a modifier added. The electrical steel sheet used was 50HXT780T (thickness: 0.5 mm) manufactured by Nippon Steel Corporation. The modifier used was Cr-50% Ni alloy powder (Wellpowder manufactured by Nippon Welding Rod Co., Ltd.). The modifier was added to the electrical steel sheet by scraping the powder off a thin plate (thickness: 0.4 mm) placed on the electrical steel sheet. The laser irradiation was performed using a single-type fiber laser (laser oscillator: YLS-2000-SM ​​manufactured by IPG Corporation, fiber core diameter: 24 μm, optical system: 3D galvanometer scanner manufactured by Yaskawa Electric Corporation, focusing diameter: 36 μm) at 340 W, 11 mm / s, amplitude width: 0.6 mm, and Ar flow conditions.

[0044] Although the locus t shown in Fig. 2B is shown as a roughly U-shaped path for convenience, it is actually a roughly linear, reciprocating path of about 4 mm. The scale shown in Fig. 2B also has a division (minimum division) of 0.5 mm.

[0045] As can be seen in Figure 2B, an unmelted area was formed near the starting point p0 of the laser irradiation, and a shrinkage cavity was formed near the end point p1. More specifically, the location where the shrinkage cavity occurred was slightly before the end point p1 (upper side of Figure 2B).

[0046] 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, defective portions of the bead (unmelted portions, shrinkage cavities) can be removed when forming the slot 101, while leaving good bead portions as the non-magnetic portion 121 of the bridge 111. It was also confirmed that the end of the bead can be contained within the gap c and prevented from crossing over onto the stator core piece 2 side.

[0047] Comparative Example (1) As a first comparative example, a case where laser irradiation was performed along the trajectory t shown in FIG. 3A was shown. An experimental example of this is shown in FIG. 3B. The trajectory t shown in FIG. 3B was a substantially linear path of approximately 10 mm. For convenience, the same reference numerals are used for the components and parts already described, and detailed descriptions thereof are omitted (the same applies hereinafter). In addition, the electromagnetic steel sheets and laser irradiation conditions used in the experiment were the same as those already described for the experimental example shown in FIG. 2B (the same applies hereinafter).

[0048] 3A has a start point p0 in the planned area for slots 101 and 102, passes through the planned areas for bridges 111 and 112, and has an end point p1 on the outer periphery thereof. In this case, a defect (shrinkage cavity) that occurs just before end point p1 does not fit within gap c and extends into an area that could become a stator core lamination 2. Considering the removal of such a defect, it is clear that rotor core laminations 1 and stator core laminations 2 cannot be simultaneously obtained from one electromagnetic steel sheet M.

[0049] (2) As a second comparative example, a case where laser irradiation was performed along the trajectory t shown in Fig. 4A was shown. An experimental example of this is shown in Fig. 4B. In this comparative example, laser irradiation was performed on a rotor core piece 1 that had been punched out first from an electromagnetic steel sheet M, and the bridges 111 and 112 were modified (demagnetized). The trajectory t of laser irradiation was the same as in the example (see Fig. 2A).

[0050] In this comparative example, defects (unmelted portions, shrinkage cavities, etc.) formed at the start point p0 and end point p1 of the laser irradiation are removed by forming the slots 101 and 102. However, defects occurred in the narrow bridges 111 and 112 on the outer peripheral end side of the rotor core piece 1 due to shrinkage cavities, etc. caused by the laser irradiation.

[0051] 《Trajectory》 (1) As long as the predetermined region can be demagnetized and the desired electromagnetic steel pieces can be separated with a good yield from the electromagnetic steel sheet after the modification process, various trajectories for scanning the beam are possible. For example, the substantially U-shaped trajectory t shown in Fig. 2A may be a substantially box-shaped (substantially U-shaped) trajectory t1 shown in Fig. 5A, or a substantially linear (reciprocating) trajectory t2 shown in Fig. 5B.

[0052] Unless otherwise specified, the locus referred to in this embodiment and this specification is the general main path that the beam center traces on the electromagnetic steel sheet. When observed in detail, the beam center may trace, for example, a secondary path that intersects or oscillates with respect to the main path. As a specific example, there is a locus that traces a zigzag secondary path ts when viewed microscopically, but traces a linear main path tm when viewed macroscopically (see Figure 6B).

[0053] (2) As shown in Fig. 6A, the slot 101 of the rotor core piece 1 is divided into, for example, two slots 1011 and 1012, left and right. At this time, nonmagnetic portions 1211 and 1212 are formed in the bridges 1111 and 1112 in the outer peripheral end regions of the slots 1011 and 1012 by the modification process described above.

[0054] It is preferable to form non-magnetic portions 1213 in the bridge 1113 formed between the slots 1011 and 1012 (in the non-peripheral region). The non-magnetic portions 1213 may be formed by irradiating the laser along a linear locus (main path tm) shown in Fig. 6B. The locus may include microscopic zigzag secondary paths ts.

[0055] Of course, nonmagnetic portion 1213 may be formed in the same manner as nonmagnetic portions 1211 and 1212 (see FIGS. 2A and 2B). That is, nonmagnetic portion 1213 may be formed by scanning a laser along a trajectory having a start point p0 and an end point p1 in one of slots 1011 and 1012 (the area to be removed) (specific irradiation step).

[0056] Furthermore, the nonmagnetic portion 1213 may be formed along a plurality of specific loci. For example, the nonmagnetic portion 1213 may be formed by scanning a laser along a first locus having a start point p0 and an end point p1 in the slot 1011 (region to be removed) and a second locus having a start point p0 and an end point p1 in the slot 1012 (region to be removed) (specific irradiation step). This also applies to the nonmagnetic portion 121 (1211, 1212). For example, the nonmagnetic portion 121 may be formed by scanning a laser along a first locus having a start point p0 and an end point p1 in the slot 101 (region to be removed) and a second locus having a start point p0 and an end point p1 in the slot 202 (region to be removed; see FIG. 1B ) on the stator core piece 2 side (specific irradiation step). [Explanation of symbols]

[0057] t-trajectory p0 starting point p1 End point M Electrical steel sheet 1 rotor core piece 2 Stator core pieces 101 Slots 111 Bridge 121 Non-magnetic part 311 Modified material layer

Claims

1. a modification step of demagnetizing a predetermined region of the electromagnetic steel sheet, the modification step includes a specific irradiation step of irradiating the electromagnetic steel sheet with a high-energy beam by scanning it along a specific trajectory, The specific trajectory passes through a planned removal area and a planned remaining area that are set adjacent to each other on the electromagnetic steel sheet, and has a start 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 a part of the intended remaining region.

3. The method for manufacturing a magnetic member according to claim 1 or 2, wherein rotor core pieces and stator core pieces are to be separated from one electromagnetic steel sheet after the modification step.

4. The method for manufacturing a magnetic member according to claim 3 , wherein the remaining region is a peripheral end region of the rotor core piece that is adjacent to the stator core piece.

5. The method for manufacturing a magnetic member according to claim 4 , wherein the modifying step forms a non-magnetic portion that penetrates substantially radially through 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 intended removal area is a slot area of ​​the rotor core piece.

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