Method and apparatus for recovering magnets from a rotor

Abstract

Multiple rotors can be processed continuously to collect magnets, reducing the workload. [Solution] A method for recovering magnets from a rotor having multiple stacked steel plates and magnets fixed in holes in the steel plates, comprising: a heating step of heating the rotor to demagnetize the magnets and embrittle the resin used to fix the magnets; a rapid cooling step of rapidly cooling the rotor after the heating step; and a vibration conveying step of conveying the rotor while applying vibration and shock after rapid cooling, wherein the vibration conveying step applies force to the steel plates and magnets in the vertical direction and in the direction along the conveying surface by vibration.

Description

Technical Field

[0001] The present invention relates to a magnet recovery method and a magnet recovery device for recovering magnets from a rotor such as a used automotive motor.

[0002] In recent years, xEVs (electric vehicles) such as electric vehicles (EVs) and hybrid electric vehicles (HEVs) have been increasing. Large drive motors are installed in xEVs, and rare earth magnets with a high procurement risk are widely used in the rotors, which are the rotors of these motors, and reliable recycling is required. With the high performance and high output of xEVs, the drive motors have also become larger and more robust in structure, and the work load of disassembling and magnet recovery has been high and inefficient.

[0003] [[ID=I2]] Hitherto, a method has generally been used in which the rotor is heated at a high temperature to demagnetize the magnet and embrittle the magnet fixing resin, the rotor is cooled to a workable temperature, and then vibration or impact is applied to the rotor or the magnet to separate and recover the magnet from the steel plate.

[0004] For example, in Patent Document 1, a shaft disposed horizontally and a vibrator for vibrating the shaft in the vertical direction are provided. The shaft is passed through a through hole of a rotor core, and the rotor core is supported in a state where there is a sufficient gap between the outer peripheral surface of the shaft below the shaft and the inner peripheral surface of the rotor core. By vibrating the shaft in the vertical direction by the vibrator, vertical vibration is applied to the rotor core, and the outer peripheral surface of the shaft and the inner peripheral surface of the rotor core are continuously collided with each other.

[0005] Further, in Patent Document 2, a method for recovering a magnet from a rotor in which a plurality of annular plate-shaped steel plates are joined and a magnet is incorporated into a hole portion and fixed by an adhesive. After heating the rotor to a temperature higher than either the Curie temperature or the ashing temperature of the adhesive to demagnetize the magnet and embrittle the adhesive, vibration that resonates with the steel plate on the end face of the rotor is applied to detach the adhesive and the magnet from the hole portion. It is disclosed that an air hammer is used as a means for applying vibration. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2011-166966 [Patent Document 2] Japanese Patent Publication No. 2015-216777 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, in many cases, the magnet fixing resin in modern motors (rotors) is not sufficiently brittle by heating alone, and the magnets cannot be separated by impact alone. In such cases, it is necessary to peel off each layer of laminated steel plates to recover only the magnets, which is extremely inefficient and labor-intensive. Furthermore, the method disclosed in Patent Document 1 involves handling each rotor by passing it onto the shaft, which is cumbersome, labor-intensive, and unsuitable for mass processing.

[0008] This invention has been made in view of these circumstances, and aims to reduce the workload by enabling the continuous processing of multiple rotors to recover magnets. [Means for solving the problem]

[0009] The present invention relates to a method for recovering magnets from a rotor having a plurality of stacked steel plates and magnets fixed in holes in the steel plates, and is a method for recovering magnets from a rotor. The process includes a heating step of heating the rotor to demagnetize the magnets and embrittle the resin used to fix the magnets, a rapid cooling step of rapidly cooling the rotor after the heating step, and a vibration transport step of transporting the rotor after rapid cooling while applying vibration and shock. In the vibration conveying process, vibration is used to apply forces to the steel plate and the magnet in the vertical direction and in the direction along the conveying surface.

[0010] This magnet recovery method involves a heating process to demagnetize the magnets and embrittle the resin, followed by a rapid cooling process to create a temperature difference between the outer surface and the center of the rotor. This difference in thermal expansion and contraction between the surface and center of the laminated steel plates, and between the steel plates and the resin, is used to deform and separate the laminated steel plates. Then, in the vibration transport process, a force is applied to the steel plates in a direction along the transport surface to transport the steel plates and magnets. This method is efficient because the transport is also performed by applying vibration.

[0011] In the rotor magnet recovery method of the present invention, the vibration conveying step is preferably performed by vibrating the conveying surface in an oblique direction. By vibrating diagonally, the diagonal force (with component forces acting in the vertical and along the conveying surface) is applied to the rotor, enabling the separation of steel plates, separation of magnets, and conveyance.

[0012] In the rotor magnet recovery method of the present invention, the vibration conveying step may be performed by inclining the conveying surface downwards in the conveying direction. By tilting the conveying surface, a force is applied to the steel plate in the direction of its surface through vibration, without the need to intentionally apply an external force in the horizontal direction. Therefore, it becomes possible to convey the steel plate efficiently.

[0013] The present invention relates to a rotor magnet recovery device for recovering magnets from a rotor having a plurality of stacked steel plates and magnets fixed in holes in the steel plates, The system includes a heating means for heating the rotor to a temperature higher than the Curie temperature or the brittleness temperature of the magnet fixing resin, a rapid cooling means for rapidly cooling the rotor heated by the heating means, and a vibrating conveying means for conveying the rotor after rapid cooling while applying vibration and shock. The vibration conveying means includes a vibration applying means that applies force to the steel plate in the vertical direction and in the direction along the conveying surface.

[0014] In the rotor magnet recovery device of the present invention, the vibration applying means may vibrate the conveying surface in an oblique direction.

[0015] In the magnet recovery device of the rotor of the present invention, the conveyance surface may be inclined downward in the conveyance direction.

Advantages of the Invention

[0016] According to the present invention, a series of operations of rapid cooling after heating and vibrating conveyance can be continuously performed, multiple rotors can be continuously processed to efficiently recover magnets, and moreover, without manual intervention, the steel plate peels off during vibrating conveyance and the magnets are separated, so the work load can be reduced.

Brief Description of the Drawings

[0017] [Figure 1] It is a plan view showing an example of a rotor handled by the magnet recovery device of one embodiment of the present invention. [Figure 2] It is a longitudinal sectional view of the rotor of FIG. 1. [Figure 3] It is a configuration diagram of the magnet recovery device of one embodiment. [Figure 4] It is a perspective view showing an example of the vibrating conveyance means in the magnet recovery device of one embodiment. [Figure 5] It is a side view of the vibrating conveyance means of FIG. 4. [Figure 6] It is a flowchart showing a magnet recovery method of one embodiment. [Figure 7] It is a perspective view schematically showing the vibrating conveyance process in the magnet recovery method. [Figure 8] It is a side view similar to FIG. 5 showing a first modification example of the vibrating conveyance means. [Figure 9] It is a side view similar to FIG. 5 showing a second modification example of the vibrating conveyance means. [Figure 10] It is a side view similar to FIG. 5 showing a third modification example of the vibrating conveyance means.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. First, let me explain the rotor. As shown in Figures 1 and 2, the rotor 1 is formed in a cylindrical shape overall by joining together multiple annularly shaped magnetic steel plates 2 in a laminated state by crimping or the like. Multiple holes 3 are formed in each steel plate 2 at intervals in the circumferential direction, and the steel plates 2 are laminated with each hole 3 communicating in the axial direction. Magnets 4 are then fixed within these communicating holes 3 by magnet fixing resin 5. For example, a silicon steel sheet with a thickness of 0.35 mm can be used as the steel plate 2, a rare earth magnet such as neodymium can be used as the magnet 4, and epoxy resin can be preferably used as the magnet fixing resin 5.

[0019] <One Embodiment> A magnet recovery device and magnet recovery method of the present invention will be described. As shown in Figure 3, the magnet recovery device 10 includes a heating means 11 for heating the rotor 1, a rapid cooling means 12 for rapidly cooling the rotor 1 heated by the heating means 11, and a vibrating conveying means 13 for conveying the rotor 1 after it has been rapidly cooled while applying vibration and shock.

[0020] As the heating means 11, a heating furnace is used, and the rotor is heated to a temperature above the higher of the Curie temperature or the embrittlement temperature of the magnet fixing resin, thereby demagnetizing the magnet 4 in the rotor 1 and embrittlement of the magnet fixing resin 5. As a cooling means 12, for example, a water tank may be used, and the rotor 1 removed from the heating means (heating furnace) 11 is cooled by submerging it in water or the like. A shower spraying water or the like onto the rotor 1 may also be used. Other possible cooling means include immersing the rotor in a device filled with a refrigerant other than water, or spraying water while blowing air onto it.

[0021] As shown in Figures 4 and 5, the vibrating conveying means 13 includes a conveying path 23 composed of a screen 21 of a predetermined length on which the rotor 1 is placed and conveyed, and side walls 22 erected on both sides of the screen 21, and a vibration applying means 24 that vibrates the conveying path 23. The screen 21 is made of a perforated plate such as punched metal, which has numerous through holes 25 formed therein. The through holes 25 are sized so that the steel plate 2 of the rotor 1 cannot be inserted through them, but the magnets 4 and magnet fixing resin 5 inside the rotor 1 can be inserted through them. Since side walls 22 are erected on both sides of the screen 21, the screen 21 and the side walls 22 together form a trough structure or a trough-shaped transport path 23 having a bottom surface and sides.

[0022] In this embodiment, the vibration-applying means 24 applies vibration and shock to the trough-structured transport path 23 while supporting it on a horizontal base 31. A vibration motor 33, with its rotation axis 32 oriented diagonally, is mounted on the outer surface of the side wall 22 of the transport path 23. The rotation of this vibration motor 33 applies diagonal vibration and shock to the transport path 23, or in other words, the screen 21. The mounting location of the vibration motor 33 is not limited to the outer surface of the side wall 22; it may also be on the underside of the transport path 23, as long as diagonal vibration and shock can be applied to the screen 21. Furthermore, in order to suppress the transmission of vibrations from the screen 21 to the base 31, an elastic member 34 is interposed between the base 31 and the transport path 23 in the vertical direction.

[0023] The vibration motor 33 has a weight eccentrically mounted on the rotating shaft 32, and the rotation of this eccentric weight can apply vibration and shock in a direction perpendicular to the rotating shaft 32. Furthermore, since the vibration motor 33 is mounted on the outer surface of the side wall 22 with the rotating shaft 32 oriented at an angle, vibration and shock can be applied to the side wall 22 at an angle. As a result of this vibration, the transport path 23 vibrates diagonally, and vibration and shock are applied to the rotor 1 on the screen 21 mainly by a component force along the thickness direction (vertical direction) of the screen 21, while the rotor 1 on the screen 21 is transported by a component force along the surface direction (horizontal direction) of the screen 21.

[0024] In this case, it is preferable to set the frequency and amplitude of the vibration applied to the screen 21 to be as large as possible in order to facilitate the disassembly and separation of the rotor 1. By changing the mounting angle of the vibration motor attached to the outer surface of the side wall 22, the force components in the thickness direction (vertical direction) and the surface direction (horizontal direction) of the screen 21 can be changed, thereby adjusting the vibration and shock applied to the rotor 1 on the screen 21 and the conveying action of the rotor 1. In addition, multiple baffle plates 35 are provided protruding from the inside of the side wall 22. These baffle plates 35 protrude toward the center in the width direction of the screen 21 and are inclined toward the downstream direction in the conveying direction, and multiple baffle plates are provided at predetermined intervals in the conveying direction. In Figure 4, reference numeral 36 indicates the steel plate discharge port at the downstream end of the transport path 23, and reference numeral 37 indicates the box that receives the steel plates 2 falling from the transport path 23.

[0025] A method for recovering the magnet 4 from the rotor 1 using the magnet recovery device 10 configured as described above will now be explained. As shown in Figure 6, this magnet recovery method includes a heating step in which the rotor 1 is heated by a heating means 11 to demagnetize the magnets 4 and embrittle the magnet fixing resin 5; a rapid cooling step in which the rotor 1 is rapidly cooled by a rapid cooling means 12 after the heating step; and a vibratory transport step in which the rapidly cooled rotor 1 is placed in a vibratory transport means 13 and transported while being subjected to vibration and shock. The following explains the process step by step.

[0026] (Heating process) In the heating process, as mentioned above, the rotor 1 is heated to a temperature higher than the Curie temperature or the embrittlement temperature of the magnet fixing resin, whichever is higher. For neodymium magnets, demagnetization occurs by holding them at a temperature of 380°C or higher (330°C to 380°C) for about 15 minutes. Regarding the embrittlement of the magnet fixing resin, although it depends on the type of resin, decomposition and embrittlement usually progress when heated to a temperature higher than the Curie temperature of the magnet. Therefore, the temperature should be set to promote the demagnetization of the magnet 4 and the embrittlement of the magnet fixing resin 5.

[0027] (Rapid cooling process) In the rapid cooling process, the rotor 1, which has reached a high temperature in the heating process, is rapidly cooled with water or the like. This rapid cooling creates a temperature difference between the surface and core of the rotor 1, and the difference in thermal expansion between the surface and core of the laminated steel plates, and between the steel plates 2 and the resin, causes the laminated steel plates 2 to deform and delaminate. Other cooling methods include, as mentioned above, immersion in liquid nitrogen, spraying with liquid nitrogen, immersion in a device filled with other refrigerants, and spraying water while blowing air. As the steel plate 2 peels off, the magnet fixing resin 5 is crushed, and the magnets 4 that were fixed to the steel plate 2 can create voids in the holes 3 of the steel plate 2. At this stage, some of the magnets 4 may fall off near the outer surface of the rotor 1, but most of them remain trapped inside the rotor 1.

[0028] (Vibration conveying process) In the vibration transport process, the rotor 1 is placed onto the screen 21 of the transport path 23 while vibration and shock are applied to the screen 21 of the vibration transport means by the vibration applying means 24. Since the screen 21 is vibrated at an angle, the rotor 1 moves in the plane direction of the screen 21 while vibrating on the screen 21. At this time, in order to apply both vibration and shock to the rotor 1, the frequency of the vibration applied by the vibration applying means 24 is set to be relatively high and the amplitude to be large.

[0029] The vibrations and shocks applied by the screen 21 to the rotor 1 accelerate the delamination of the steel plate 2, and as schematically shown in Figure 7, the magnet fixing resin 5, which had been brittle in the previous step, collapses, separating the magnet 4 from the steel plate 2. Multiple steel plates 2 are stacked, and magnets 4 were fixed in holes 5 in each of these steel plates 2. However, due to the oblique vibrations and shocks, the delaminate steel plates 2 shift in the planar direction, and the magnets 4 fixed inside also fall out of the holes 5 as the steel plates 2 shift. Furthermore, during the transport process, the detached steel plates 2 collide with each other due to vibration and impact, which promotes the detachment of individual steel plates 2 and the separation of magnets 4. After detachment, the steel plates 2 are more susceptible to the vibration and impact applied from the screen 21 than before detachment, which promotes the detachment of magnets 4.

[0030] Then, the magnet 4 and magnet fixing resin 5 that have separated and fallen from the steel plate 2 are transported on the screen 21 and fall below the screen 21 through the through holes 25 formed in the screen 21. On the other hand, since the steel plate 2 is larger than the through holes 25, it is transported on the screen 21 and sent downstream, falls out of the steel plate discharge port 36, and only the steel plate 2 can be collected in the box 37. In this case, since multiple baffles 35 are provided protruding from the inside of the side wall 22, when the rotor 1 and steel plate 2 approach both sides in the width direction of the screen 21, the baffles 35 move them towards the center of the screen 21 in the width direction, and vibration and shock are applied appropriately.

[0031] Furthermore, as mentioned above, the steel plate 2 peels off in the rapid cooling process, which is the preceding process of the vibrating conveying process. However, in this vibrating conveying process, vibration and shock are applied to the steel plate 2, causing it to peel off and making it easier for the magnet 4 to detach from the steel plate 2. Furthermore, when loading the rotor 1 onto the screen 21 of the transport path 23, it is preferable to drop the rotor 1 from above, as this allows for a greater impact force to be applied to the rotor 1. Additionally, it is preferable to change the plate on the dropping surface to one equipped with protrusions, as this promotes the peeling of the steel plate 2.

[0032] As described above, the magnets 4 inside the rotor 1 can be separated from the steel plates 2 and recovered. In this case, the rotor 1, which has been demagnetized and the resin embrittlemented by heating and rapid cooling, is subjected to vibration and shock during transport, causing the rotor 1 to disassemble and the steel plates 2 to peel off. Since this vibration and shock are applied diagonally, they act not only vertically but also horizontally, allowing the rotor 1 to move (transport) in the planar direction. At that time, the peeled steel plates 2 are transported while shifting in the planar direction, making it easier for the magnets 4, which were held in place by the stacked steel plates 2, to detach from the holes 5 in the steel plates 2. In this way, the vibration transport process allows for the simultaneous detachment of the steel plate 2 and separation of the magnet 4, making it efficient. The detached magnet 4 falls through the through-hole 25 of the screen 21, so it can be recovered separately from the steel plate 2.

[0033] <Modified examples of vibratory conveying means> The following describes three variations of the vibration conveying means. In all of these variations, the conveying path (screen 21 and side walls 22) 23, base 31, etc. of the vibration conveying means are the same as in one embodiment, but some of the configurations of the vibration applying means differ from one embodiment.

[0034] [First variation] In the first modified example, the vibration conveying means 40, as shown in Figure 8, comprises a vibration applying means 41 which includes a motor 42 mounted on a base 31 and a crank mechanism 44 connected to the rotation shaft 43 of the motor 42. In this case, the motor 42 is mounted horizontally with its rotation shaft 43 facing both sides of the screen 21, and the crank mechanism 44 has a driven rotation shaft 45 rotatably supported on the base 31 to the side of the motor 42, with one end of a connecting rod 46 held eccentrically on this driven rotation shaft 45, and the tip of the connecting rod 46 supported on the side wall 22 of the conveying path 23. In this case, the connecting rod 46 is mounted diagonally to the side wall 22 of the conveying path 23 with respect to the horizontal direction of the screen 21, and its tip is held pivotably on the side wall 22. That is, the tip of the connecting rod 46 does not move in the longitudinal direction relative to the side wall 22, but is held pivotably around its tip.

[0035] Furthermore, the elastic members 14, such as springs, interposed between the transport path 23 and the base 31 are positioned diagonally in approximately the same direction as the connecting rod 46. To hold these elastic members 14 and the connecting rod 46 in a diagonal direction, the transport path 23 and the base 31 are connected by a connecting link 47.

[0036] In this vibration transport means 40, when the motor 42 of the vibration applying means 41 rotates, the driven rotating shaft 45 rotates due to the rotation, and the base end of the connecting rod 46, which is eccentrically connected to the driven rotating shaft 45, rotates, causing the tip of the connecting rod 46 to oscillate and vibrate the side wall 22 at an angle. As a result, vibration and shock are applied to the screen 21 at an angle. The elastic member 14, such as a spring, increases the amplitude through resonance with the vibrating transport path 23. At the same time, it suppresses the transmission of vibrations from the transport path 23 to the base 31.

[0037] [Second variation] In the second modified example, the vibration conveying means 50, as shown in Figure 9, comprises a vibration applying means 51 which includes a motor 52 mounted on the outer surface of the side wall 22 and an eccentric weight 53 rotated by the motor 52. In this case as well, the rotation axis 54 of the motor 52 is mounted horizontally toward both sides of the screen 21, and the eccentric weight 53 is mounted eccentrically with respect to a horizontal driven rotation axis 55 rotated by the motor 52. Both the motor 52 and the eccentric weight 53 are attached to the outer surface of the side wall 22 of the conveying path 23, and vibration and shock are applied to the conveying path 23 by the rotation of the eccentric weight 53. Furthermore, an elastic member 14 is interposed between the transport path 23 and the base 31 in an oblique direction, similar to the first modified example. To hold this elastic member 14 in an oblique direction, the transport path 23 and the base 31 are connected by a connecting link 47. The elastic member 14, such as a spring, increases the amplitude through resonance with the vibrating transport path 23. At the same time, it suppresses the transmission of vibrations from the transport path 23 to the base 31.

[0038] In this vibration transport means 50, when the motor 52 of the vibration applying means 51 rotates, the eccentric weight 53 rotates as a result of that rotation. Since the transport path 23 is supported so as to be movable in an oblique direction by the elastic member 14 and the connecting link 47, the rotational motion of the eccentric weight 53 applies vibration and shock to the transport path 23 in an oblique direction.

[0039] [Third variation] The third modified example of the vibration conveying means 60, as shown in Figure 10, is similar to the first and second modified examples in that the vibration applying means 61 has an oblique elastic member 14 and a connecting link 47 between the base 31 and the conveying path 23, but differs in that the conveying path 23 is driven by a cylinder 62 that uses air or liquid fluid pressure attached to the base 31. This cylinder 62 is installed between the transport path 23 and the base 31 in the same oblique orientation as the elastic member 14, and the tip of its cylinder rod 63 is fixed to the side wall 22 of the transport path 23, and vibration and shock are applied by reciprocating the transport path 23 in an oblique direction.

[0040] In any of the above modifications, by vibrating the transport path 23 in an oblique direction, the screen 21 is subjected to oblique vibration and impact, similar to the first embodiment, causing the steel plate 2 of the rotor 1 to peel off and the magnet 4 to separate during transport, and a series of operations can be efficiently carried out, including separating and recovering the magnet 4 and the steel plate 2 through the screen 21 having through holes 25.

[0041] Although embodiments of the present invention have been described above, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. For example, in all vibration-applying means, the screen 21 was positioned horizontally, but the screen itself may be positioned with a downward slope toward the downstream direction of the conveying direction relative to the horizontal direction. In that case, the vibration and shock may be applied in the vertical direction rather than diagonally. The point is that when vibration and shock are applied to the screen 21, a force should be applied to the steel plate 2 in the direction of the screen 21's surface (conveying direction). [Explanation of symbols]

[0042] 1 rotor 2 steel plate 3 holes 4 Magnets 5. Resin for fixing magnets 10 Magnet recovery device 11 Heating means 12. Rapid cooling methods 13 Vibration conveying means 21 screens 22 Side wall 23 Conveyor path 24 Vibration-applying means 25 Through holes 31 Base 32 Rotation axis 33 Vibration motor 34 Elastic members 35 Obstacle board 36 Steel plate outlet 37 boxes 40 Vibration conveying means 41 Vibration-applying means 42 motors 43 Rotation axis 44 Crank mechanism 45 Driven rotating shaft 46 connecting rods 47 Linking Links 50 Vibration conveying means 51 Vibration-applying means 52 Motors 53 Eccentric weight 54 Rotation axis 55 Driven rotating shaft 60 Vibration conveying means 61 Vibration-applying means 62 cylinders 63 Cylinder rod

Claims

1. A method for recovering magnets from a rotor having multiple stacked steel plates and magnets fixed in holes in the steel plates, The process includes a heating step of heating the rotor to demagnetize the magnets and embrittle the resin used to fix the magnets, a rapid cooling step of rapidly cooling the rotor after the heating step, and a vibration transport step of transporting the rotor after rapid cooling while applying vibration and shock. A method for recovering magnets from a rotor, characterized in that the vibration conveying process applies force to the steel plate and the magnet in the vertical direction and in the direction along the conveying surface by vibration.

2. The method for recovering magnets from a rotor according to claim 1, characterized in that the vibration conveying step involves vibrating the conveying surface in an oblique direction.

3. The method for recovering magnets from a rotor according to claim 1, characterized in that the vibration conveying step is such that the conveying surface is inclined downward in the conveying direction.

4. A device for recovering magnets from a rotor having multiple stacked steel plates and magnets fixed in holes in the steel plates, The system includes a heating means for heating the rotor to a temperature higher than the Curie temperature or the brittleness temperature of the magnet fixing resin, a rapid cooling means for rapidly cooling the rotor heated by the heating means, and a vibrating conveying means for conveying the rotor after rapid cooling while applying vibration and shock. The rotor magnet recovery device is characterized in that the vibrating conveying means has a vibration applying means that applies force to the steel plate in the vertical direction and in the direction along the conveying surface.

5. The rotor magnet recovery device according to claim 4, characterized in that the vibration applying means vibrates the conveying surface in an oblique direction.

6. The rotor magnet recovery device according to claim 4, characterized in that the conveying surface is inclined downward in the conveying direction.

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