Recycling method for stators with amorphous multilayer cores

Abstract

This invention provides a method for recycling stators having amorphous laminated cores that enable the efficient separation of expensive materials. [Solution] The present invention relates to a method for recycling a stator having an amorphous laminated core, comprising a stator core 4 and a winding 5 wound around the stator core, wherein at least the portion of the stator core around which the winding is wound is an amorphous laminated core in which amorphous material is laminated, and the method comprises the steps of sequentially performing: heating the stator to embrittle the amorphous material; applying an external force to the stator to cause cracks in the stator core; and separating the winding and the stator core. The amorphous laminated core can be one which is laminated and bonded with resin. Furthermore, the heating in the embrittlement step can be performed in conjunction with a rotor with magnets attached to the stator, and can also serve as a demagnetization step for the magnets.

Description

Technical Field

[0001] The present invention relates to a stator, which is a main winding component such as a motor or a generator, and particularly relates to a recycling method for a stator having an amorphous laminated core.

Background Art

[0002] In recent years, amorphous materials, which have much better magnetic properties than non-oriented electrical steel sheets, have been attracting attention, and various proposals have been made in the field of rotating electrical machines such as motors. As application parts of magnetic materials constituting a motor, there are a rotating rotor and a fixed stator. In particular, for a stator, which is a winding component that requires particularly good frequency characteristics, the application of an amorphous material is considered suitable. As a stator core constituting a stator, for example, as described in Citation Document 1, it is known to apply an amorphous laminated core. The stator core described in Citation Document 1 is an integral body in the circumferential direction. On the other hand, as described in Citation Document 2, it is also known to form a stator core by combining core pieces divided in the circumferential direction.

[0003] By the way, as described in Citation Document 3, amorphous materials often contain expensive elements. Particularly for transformer applications, recycling technologies applying a pulverizing and cleaning process have been proposed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] In stators comprising a stator core and wound wires, expensive materials such as copper are used for the windings. Furthermore, when amorphous laminated cores are used as stator cores, expensive raw materials such as boron are often used to impart amorphous properties. Therefore, establishing recycling technologies for these materials is a crucial issue.

[0006] In view of the above, the object of the present invention is to provide a method for recycling a stator having an amorphous laminated core that enables the efficient separation of expensive materials. [Means for solving the problem]

[0007] This invention relates to a stator core and The windings wound around the stator core, It is equipped with, The stator recycling method for a stator in which an amorphous laminated core, in which amorphous material is laminated, is arranged, at least the portion of the stator core around which the windings are wound. A step of heating the stator to embrittle the amorphous material, A step of applying an external force to the stator to cause a crack in the stator core, A step of separating the winding and the stator core, This is a recycling method for stators having amorphous laminated cores, which involves performing the following steps sequentially.

[0008] The present invention can be applied to amorphous laminated cores bonded together with resin.

[0009] Furthermore, in the present invention, the heating in the embrittlement step is carried out in conjunction with the rotor with magnets that are paired with the stator, and can also serve as a demagnetization step for the magnets. [Effects of the Invention]

[0010] According to the present invention, it becomes possible to easily separate the windings and amorphous material from the stator, making it an effective technology for realizing efficient resource utilization. [Brief explanation of the drawing]

[0011] [Figure 1] This is a plan view illustrating an example of the configuration of a stator and rotor in a motor. [Modes for carrying out the invention]

[0012] Embodiments of the present invention will be described in detail below with reference to the drawings, but the present invention is not limited thereto. The inventors recognized that a problem in recycling stators with amorphous laminated cores lies in the difficulty of separating the windings. Figure 1 shows a cross-sectional view illustrating an example of the configuration of a stator and rotor in a typical motor. Figure 1 shows a stator 1 and a rotor 2. In Figure 1, the rotor 2 has a structure in which magnets 3 are installed in four locations. The stator 1 comprises a stator core 4 and windings 5. The windings 5 ​​are made of, for example, copper wire.

[0013] The stator core 4 comprises a back yoke section 6 and multiple tooth sections 7. Each tooth section 7 has a pole section 8 at its tip. The width of the pole section 8 is greater than the width of the tooth section 7. The pole section 8 is effective in reducing torque ripple, which is a cause of vibration during motor rotation. The pole section 8 is also referred to as an extension section.

[0014] The stator core 4 has a portion around which the winding 5 is wound (hereinafter referred to as the winding portion 4A). In the configuration shown in Figure 1, the winding portion 4A is included in the teeth portion 7. As the magnetic material applied to the stator core 4, for example, the tooth portion 7 and the other portions can be made of different materials, or they can be made of the same material. Also, as shown in FIG. 1, the stator core 4 may be an integral part in the circumferential direction, or may be divided in the circumferential direction. In the present embodiment, at least the portion of the stator core around which the winding is wound is configured such that an amorphous laminated core in which amorphous materials are laminated is disposed. In that case, the stator core 4 is an integral part of the amorphous laminated core, or has a configuration in which a plurality of amorphous laminated cores are stacked in the height direction.

[0015] The wound winding cannot be easily separated depending on the shape of the stator core and the like. Therefore, when recovering the winding, although it is simple to unwind or cut the winding, it takes a lot of man-hours. In the present embodiment, as described above, at least the portion of the stator core around which the winding is wound is configured such that an amorphous laminated core in which amorphous materials are laminated is disposed. This configuration merely attempts to utilize the advantageous magnetic properties of the amorphous laminated core, and the problem of recovering the winding still exists.

[0016] The amorphous material has the property of becoming brittle when heated, and becomes even more brittle when crystallized due to the presence of additive elements for imparting amorphous forming ability such as B (boron) and Si (silicon). The inventor of the present invention utilized this property and conceived that if the stator core is made brittle, the separation of the winding becomes easy, and thus the present invention was found. In this embodiment, a step of heating the stator to embrittle the amorphous material is applied. When heated, the amorphous material irreversibly embrittles even at a temperature below the crystallization temperature Tx. On the other hand, excessive heating beyond the crystallization temperature Tx is a waste of energy. Therefore, the heating temperature can be appropriately selected. Preferably, it is about Tx - 100°C to Tx + 50°C as indicated by the crystallization temperature Tx, and for a Fe - Si - B - based amorphous material, it is about 400°C to 550°C. It is reasonable to hold the heating temperature for about 10 minutes to 2 hours.

[0017] In transformers etc., the amorphous ribbon can be used almost as it is, and annealing emphasizing magnetic properties is applied, so it is originally in a brittle state. On the other hand, for the stator core, fine processing such as the formation of the pole portion 8 is required, and since it is close to the rotor which is a necessary driving part, it must not be damaged and is applied in a tough state. In this regard, the step of heating the stator in the present invention to embrittle the amorphous material is effective. As the amorphous material constituting the stator core to which this embodiment is applied, its preferable toughness is that in the tearing brittleness defined in JIS C 2534:2017, the brittleness code is 3 or less. Such an amorphous material with high toughness can be obtained by not performing heat treatment particularly after casting, or by heat treatment within a range where toughness is allowed. As a heat treatment capable of maintaining toughness, for example, a method of rapid heating and rapid cooling can also be used.

[0018] In this embodiment, next, a step of applying an external force to the stator to cause cracks in the stator core is applied. The amorphous material of the stator that has undergone the embrittling step becomes brittle and is likely to crack. Therefore, an external force is applied to cause cracks. The occurrence of cracks makes it easier for the stator core and the winding to separate. The cracks may be partial or may be developed to separate into pieces. If it is pulverized into pieces, the stator core and the winding become even easier to separate. External forces can be applied, but are not limited to, compression, tension, and torsion. For example, a vibratory mill, a single-shaft mill, or a twin-shaft mill may also be used. However, applying a mill that performs shearing to the stator may cut the winding itself. Since this can lead to problems such as the effort required to recover the winding and the inclusion of constituent elements of the winding as impurities, it is preferable to apply an external force that does not cut the winding itself.

[0019] In this embodiment, the next step is to separate the windings from the stator core. If the stator core has been crushed into individual pieces, a sieve or magnetic separation can be used. Even if it has not been crushed into individual pieces, the windings may be pulled to separate them from the brittle stator core. This separation allows for the recovery of the winding's constituent elements, generally copper. Meanwhile, amorphous material can be recovered from the stator core. This amorphous material can then be reused as a raw material by re-pulverizing it or melting it down. For Fe-Si-B amorphous materials, a useful application is reuse as a raw material for ferroboron.

[0020] Furthermore, as described above, this embodiment can be applied to amorphous laminated cores bonded together with resin. The type of resin is not particularly limited, but it is preferable that the adhesive strength decreases due to decomposition or embrittlement in the process of heating the stator and embrittlement the amorphous material. Examples include thermosetting resins that decompose when heated above a certain temperature, such as epoxy resins and thermosetting acrylic resins, and various thermoplastic resins.

[0021] Furthermore, as described above, in this embodiment, the heating in the embrittlement process is carried out in conjunction with the rotor with magnets that are paired with the stator, and can also serve as a demagnetization process for the magnets. As shown in Figure 1, in a motor, the stator 1 has a corresponding rotor 2. In the case of a rotor 2 with magnets, the magnets must be demagnetized in order to recycle them from the rotor. Rare earth magnets, in particular, generate a strong magnetic field, so they cannot be removed as is. Therefore, it is reasonable to demagnetize them thermally by heating them to a temperature above the Curie point TC. The Curie point Tc of an Nd-Fe-B magnet is around 330°C, and if the stator and rotor are heated to a temperature above the Curie point Tc in the embrittlement process of this embodiment, the process can also serve as a demagnetization process for the magnets. The Curie point Tc of an Nd-Fe-B magnet is below the preferred heating temperature in the embrittlement process of this embodiment described above, making it a reasonable process. At this time, it is not limited to heating specific component combinations such as the stator and rotor; the entire motor may be heated. Furthermore, the heating conditions for the demagnetization process and the embrittlement process can be optimized from the standpoint of thermal management, etc. Of course, the embrittlement process can be performed on the stator alone after separating the rotor and stator.

[0022] Furthermore, while the amorphous material applied to this embodiment is not limited to any particular composition, typical examples include Fe-based amorphous materials, such as the Fe-Si-B system. By using an Fe group, the high saturation magnetic flux density required for a stator can be obtained. In addition to the Fe-Si-B system, there are also materials with added C (carbon) or P (phosphorus). Furthermore, the amorphous material of this embodiment can typically be obtained by a single-roll method, in which molten metal is extruded onto a cooling roll to form a thin strip. The resulting amorphous material typically has a thickness of 20 to 50 μm and a width of 10 mm to 1000 mm. The stator core in this embodiment is obtained, for example, by adjusting the width of a thin strip of amorphous material by slitting, forming the stator shape by press punching or etching, and lamination to obtain the height of the stator core. To improve punchability, a laminated material with multiple layers bonded together may be prepared in advance before press punching. [Examples]

[0023] (Example 1) Amorphous material (manufactured by Proterial Co., Ltd., product name: Metglas® 2605HB1M) was prepared. The thickness of the thin strip of amorphous material was 25 μm, and the width after slitting was 70 mm. The composition was 100 atomic percent each for Fe, Si, and B, with Fe: 82 atomic percent, Si: 4 atomic percent, and B: 14 atomic percent. Furthermore, this amorphous material possessed high toughness, exhibiting a brittleness code of 3 or less according to the tear brittleness standards defined in JIS C 2534:2017. Ninety unit pieces were manufactured by press stamping. The shape of the unit piece, as viewed from the thickness direction, was the same as the stator core 4 shown in Figure 1. The outer diameter of the stator core is φ50 mm, and the inner diameter is φ26 mm. A stator core 4, consisting of an amorphous laminated core, was fabricated by laminating 90 unit materials in the thickness direction of each unit material using a thermosetting acrylic resin adhesive. The adhesive was cured at a temperature of 170°C for 2 hours during the lamination process. The packing ratio of the stator core 4 was 90%.

[0024] As shown in Figure 1, a stator 1 was fabricated by winding a winding 5 made of enameled copper wire with a diameter of φ0.7 mm 10 times around each tooth portion 7 of the stator core 4. The obtained stator 1 was subjected to a heat treatment in air to embrittle the amorphous material. The heat treatment profile involved raising the temperature from room temperature to 370°C in 30 minutes under a nitrogen atmosphere, then raising it to 500°C in 30 minutes, holding it at 500°C for 1 hour, and finally cooling it in the furnace to room temperature with the heater turned off.

[0025] Next, with the back yoke section 6 fixed in place, one tooth section 7 was grasped with pliers in order to apply external force. When then bent relative to the back yoke section 6, a crack formed in the back yoke section 6 connected to the grasped tooth section 7, causing it to split and the tooth section 7 to break apart.

[0026] By lightly impacting the separated teeth portion 7, small pieces of amorphous material that had remained inside the winding 5 were able to fall off. This allowed the winding 5 to be removed and separated while its winding shape was substantially preserved. This confirmed the ease of recycling according to this embodiment. Furthermore, the heat treatment applied in this embodiment to embrittle the magnets at 500°C for 1 hour exceeds the Curie point of Nd-Fe-B rare-earth magnets. Therefore, it was confirmed that performing the heat treatment together with a rotor equipped with a magnet that is paired with the stator can also serve as a demagnetization process for the magnets.

[0027] (Example 2) To verify the usefulness of the process of embrittlement of amorphous material in this embodiment, an evaluation experiment was conducted by changing the resin used for lamination bonding, which is intended for the stator, from Example 1.

[0028] An amorphous material similar to that used in Example 1 (manufactured by Proterial Co., Ltd., product name: Metglas® 2605HB1M) was prepared. The thin strip of amorphous material had a thickness of 25 μm and a width of 25 mm after slitting. This was cut into strips measuring 50 mm in length and 25 mm in width. The 90 obtained strips were laminated and bonded together with epoxy resin to form an amorphous laminated core, and a laminate for stator evaluation was fabricated. In the adhesive lamination process, the adhesive was cured at a temperature of 150°C for 15 minutes. The packing ratio of the laminate was 90%.

[0029] The resulting laminate was subjected to a heat treatment in air to embrittle the amorphous material. The heat treatment profile involved raising the temperature from room temperature to 370°C in 30 minutes under a nitrogen atmosphere, then raising it to 500°C in 30 minutes, holding it at 500°C for 0.5 hours, and finally cooling it in the furnace to room temperature with the heater turned off. To confirm the progression of embrittlement in the laminate after heat treatment, an evaluation was performed using a micro-Vickers tester (manufactured by Mitutoyo Corporation, product name: HM-220D).

[0030] The evaluation involved applying an indenter to the surface of a laminate fixed on an aluminum plate with a load of 4.90 N. As a result, cracks with a radius of 50 μm or more were observed, with the center of the circle being the center of the Vickers mark. For comparison, a laminate that had not undergone heat treatment was evaluated in the same way, but no cracks were observed. From this, it was confirmed that the embrittlement process in this embodiment is also effective for epoxy resin. [Explanation of symbols]

[0031] 1: Status 2: Rotor 3: Magnets 4: Stator core 4A: Winding section 5: Winding 6: Back yoke section 7: Teeth Department 8: Pole section

Claims

1. Stator core and The windings wound around the stator core, It is equipped with, The stator recycling method for a stator in which an amorphous laminated core, in which amorphous material is laminated, is arranged, at least the portion of the stator core around which the windings are wound. A step of heating the stator to embrittle the amorphous material, A step of applying an external force to the stator to cause a crack in the stator core, A step of separating the winding and the stator core, A method for recycling a stator having an amorphous laminated core, characterized by performing the following steps sequentially.

2. The method for recycling a stator having an amorphous laminated core according to claim 1, characterized in that the amorphous laminated core is laminated and bonded with a resin.

3. The method for recycling a stator having an amorphous laminated core according to claim 1, characterized in that the heating in the embrittlement step is carried out together with a rotor with magnets attached to the stator, and also serves as a demagnetization step for the magnets.

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