Rotor, method of manufacturing a rotor, and motor

Abstract

The present application is to provide a rotor which reduces the number of components, reduces manufacturing costs, and realizes weight reduction. As a solution, a plurality of plate-shaped magnets (6) positioned in the radial and axial directions are arranged at a prescribed interval on the inner peripheral surface (5a) of the rotor yoke (5), a partition portion (8c) separating each plate-shaped magnet (6) is formed by curing a first adhesive (8a) at each first adhesive portion (6a), and the plurality of plate-shaped magnets (6) are separated from each other at a prescribed interval by the partition portion (8c) in the circumferential direction, and are adhered and fixed at a second adhesive portion (6b).

Description

TECHNICAL FIELD

[0001] The present application relates to a rotor of a motor, a manufacturing method of the rotor, and a motor. BACKGROUND

[0002] For example, in a high-output motor, as a rotor magnet, a rare-earth magnet in which neodymium or the like is a main component is used. In the case where a rare-earth magnet is used to manufacture a multi-pole magnet, in order to achieve weight reduction and cost reduction, instead of using a ring-shaped magnet, a segment magnet that is divided into segments for each pole is used. However, it is difficult to arrange and dispose the segment magnets along the circumferential direction of a rotor yoke and fix them to a prescribed position. The magnetic force of a rare-earth magnet is stronger than that of a ferrite magnet, but on the other hand, it is prone to rust, and thus, in order to improve corrosion resistance, nickel plating is performed to perform rust-proof treatment on the surface. Moreover, the frictional force of an adhesive-coated adhesive surface at the time of wetting is reduced, and thus, the magnet is prone to move. In particular, if an epoxy resin-based adhesive is used, the viscosity of the adhesive temporarily decreases in a heat curing process, and thus, the position of the magnet is prone to shift. If the position of the magnet shifts, the motor characteristics are reduced, and motor vibration or noise can occur.

[0003] Therefore, for example, in a rotor of an outer rotor type motor, as shown in Figure 6A , a plurality of segment magnets 52 are positioned and held with respect to a cylindrical rotor yoke 51 using positioning members 53, and the segment magnets 52 are positioned and adhesively fixed in the radial and axial directions. The ring-shaped linking portions 53a of the positioning members 53 are erected at prescribed intervals in a comb-tooth shape as partition members 53b. The ring-shaped linking portions 53a prescribe the axial position of the segment magnets 52, and the partition members 53b prescribe the radial position. After the positioning members 53 are inserted from an end side opening portion of the rotor yoke 51 along the inner circumferential surface 51a, the segment magnets 52 coated with an adhesive 54 are inserted between the partition members 53b from the other end side opening portion of the rotor yoke 51 and are adhesively fixed (see Figure 6A ). Then, the adhesive 54 is heat cured to adhesively fix the segment magnets 52 and the positioning members 53 to the inner circumferential surface 51a of the rotor yoke 51 (see Figure 6B ). Thereafter, a rotor hub 56 that is integrally assembled with a rotor shaft 55 is press-fitted and fixed to the rotor yoke 51 (see Figure 6C ), and an outer rotor type rotor 57 that can rotate about the rotor shaft 55 is formed (see Figure 6D ).

[0004] Similarly, in a rotor of an inner rotor type motor, after the positioning members 53 are attached from the one axial side to the outer circumferential surface 51b of the cylindrical rotor yoke 51 centered on the rotor shaft 55, the segment magnets 52 coated with the adhesive 54 are inserted between the partition members 53b from the other axial side and are adhesively fixed (see Figure 7A). Then, a rotor of an inner rotor type is formed, and the adhesive 54 is heat-cured to adhere and fix the segment magnets 52 to the outer peripheral surface 51b of the rotor yoke 51 together with the positioning members 53 (see Figure 7B ).

[0005] Further, a technology is proposed to enhance the fixing force of the magnets installed in the rotor yoke of an outer rotor type motor to prevent the magnets from falling over during assembly, thereby improving workability. A cylindrical inner housing is inserted into the inner surface side of a cylindrical rotor outer cylinder, and a resin retaining ring is integrally assembled between the rotor outer cylinder and the inner housing, and the resin retaining ring is provided with a plurality of magnets arranged in the circumferential direction with a partition piece therebetween (see Patent Document 1: Japanese Patent Laid-Open No. 2003-304660).

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Laid-Open No. 2003-304660 SUMMARY

[0009] PROBLEMS TO BE SOLVED BY THE INVENTION

[0010] However, in the Figure 6D and Figure 7B or Patent Document 1, since the segment magnets 52 are adhered and fixed to the inner peripheral surface 51a or the outer peripheral surface 51b of the rotor yoke 51 together with the positioning members 53, if the adhesive is heat-cured, the positioning members 53, which are originally unnecessary, will be adhered to the rotor yoke 51 together with the segment magnets 52, so that the positioning members 53 cannot be removed. Further, the resin retaining ring of Patent Document 1 is used as a member essential for fixing the magnets.

[0011] Thus, the operation of assembling the originally unnecessary positioning members 53 or the resin retaining ring to the rotor 57 will not only increase the number of components and increase the manufacturing cost, but also increase the weight of the motor.

[0012] Further, if the segment magnets 52 are adhered and fixed to the rotor yoke 51 without using the positioning members 53, as shown in Figure 8A , in order to position the segment magnets 52 to the inner peripheral surface of the rotor yoke 51, it is necessary to alternately form the recesses 51a and the protrusions 51b in the circumferential direction. Or as shown in Figure 8B , it is necessary to provide comb-shaped positioning members 56a to the outer peripheral edge portion of the rotor hub 56 pressed into the rotor yoke 51. In either case, the processing time of the components will be increased, thereby increasing the manufacturing cost.

[0013] TECHNICAL SOLUTION

[0014] The present application has been made to solve the above technical problems, and aims to provide a rotor which reduces the number of components, reduces manufacturing costs, and realizes weight reduction, a manufacturing method of a rotor which is excellent in assembly because it can position plate magnets in the radial and axial directions and assemble the plate magnets to a rotor yoke, and a motor which is inexpensive and excellent in assembly, can maintain motor characteristics, and uses the rotor.

[0015] To solve the above technical problems, the present application at least includes the following structure.

[0016] A rotor, the rotor including plate magnets divided into a plurality of pieces at a regular interval in the circumferential direction on the circumferential surface of a rotor yoke, wherein each of the plate magnets is a flat plate magnet, a first adhesive portion and a second adhesive portion are formed on the adhesive surfaces of the plate magnets adjacent to or partially overlapping each other using a plurality of adhesives having different curing conditions, the first adhesive portion is coated with a first adhesive which cures at a regular time, the second adhesive portion is coated with a second adhesive which requires a longer curing time than the first adhesive but has a higher adhesive strength, and a gap portion formed between the curved surface of the rotor yoke and the flat plate surface of the plate magnet is formed as an adhesive storage portion of the first adhesive and the second adhesive to form an adhesive layer,

[0017] The plurality of plate magnets disposed on the circumferential surface of the rotor yoke are formed with a partition portion separating each of the plate magnets in the circumferential direction by curing the first adhesive, and the plurality of plate magnets are partially adhered at the first adhesive portion and positioned in the radial and axial directions, and the plurality of plate magnets are separated from each other in the circumferential direction by the partition portion at a regular interval by heat curing of the second adhesive, and are adhered and fixed at the first adhesive portion and the second adhesive portion.

[0018] Thus, the plurality of plate magnets are positioned in the radial and axial directions and disposed at a regular interval on the circumferential surface of the rotor yoke using a positioning member, and the plate magnets are positioned in the circumferential and axial directions with respect to the rotor yoke and partially adhered at the first adhesive portion by curing the first adhesive and forming the partition portion separating each of the plate magnets.

[0019] Further, the plurality of plate magnets are adhered and fixed at the first adhesive portion and the second adhesive portion in the circumferential direction via the partition portion by curing the second adhesive, and thus, the positioning member which is not originally required can be reduced, manufacturing costs can be reduced, and weight reduction of the rotor can be realized.

[0020] In addition, since the plurality of flat plate magnets can be adhered to the rotor yoke at a regular interval and positioned in the circumferential direction via the partition portion formed by curing the first adhesive, compared to a ring magnet, cost reduction can be realized, the position accuracy of the plate magnets with respect to the rotor yoke in the radial and axial directions can be high, and assembly can be performed without positional deviation.

[0021] In particular, since no special processing is required for the bonding of the plate-shaped magnets, not only can the manufacturing cost be reduced, but also the gap portion formed between the curved surface of the bonding surface of the rotor yoke and the flat surface of the plate-shaped magnets can be used as a bonding agent storage portion of the first and second bonding agents and as a sufficient bonding space, so that the bonding strength of the first and second bonding portions can be maintained. In addition, in the case of irradiating ultraviolet rays when bonding the flat plate-shaped magnets to the first bonding portion, a sufficient space for irradiating ultraviolet rays from the gap between the curved surface and the flat surface can be ensured

[0022] Ideally, the above-mentioned plate-shaped magnets are rare-earth magnets with a rust-preventive surface treatment, and the first and second bonding agents are interposed in the gap between the rotor yoke and the plate-shaped magnets.

[0023] Thus, different types of bonding agents having different curing conditions can be used to bond and fix the high-output plate-shaped magnets to the rotor yoke without positional deviation.

[0024] Ideally, the second bonding portion has the same area as the first bonding portion or a larger area than the first bonding portion, with respect to the area of the first bonding portion and the second bonding portion of the bonding surface of the above-mentioned plate-shaped magnets.

[0025] Thus, the final bonding strength of the plate-shaped magnets to the rotor yoke can be maintained.

[0026] The first bonding agent can be an ultraviolet-curable bonding agent or a combination of an ultraviolet-curable bonding agent and an anaerobic-curable bonding agent.

[0027] Thus, by irradiating ultraviolet rays only on the first bonding agent layer interposed between the plate-shaped magnets and between the plate-shaped magnets and the rotor yoke, a partition portion (first bonding agent cured portion) that cures the first bonding agent in a short time and separates the plate-shaped magnets can be formed, so that the plate-shaped magnets can be easily partially bonded to the rotor yoke. In addition, when the second bonding agent is heat-cured, since the plate-shaped magnets are positioned in the circumferential direction by the partition portion and are partially bonded by the first bonding portion, positional deviation does not occur.

[0028] The rotor of an outer rotor type motor in which the plate-shaped magnets divided in the circumferential direction are fixed at a prescribed interval on the inner circumferential surface of the rotor yoke formed in a cup shape, or the rotor of an inner rotor type motor in which the plate-shaped magnets divided in the circumferential direction are fixed at a prescribed interval on the outer circumferential surface of the rotor yoke formed in a cylindrical shape can also be used.

[0029] Compared with a ring-shaped magnet, cost reduction and weight reduction can be achieved, and the plate-shaped magnet can be assembled with high positional accuracy in the radial and axial directions with respect to the rotor yoke, regardless of whether it is an outer rotor type or an inner rotor type.

[0030] In a motor, by a stator including any one of the above-described rotors and stator teeth opposite the plate-shaped magnets of the rotor, an outer rotor type motor or an inner rotor type motor that is inexpensive, lightweight, has good assembly, and can maintain motor characteristics can be provided.

[0031] A manufacturing method of a rotor, characterized by comprising: a process of applying a first adhesive that solidifies in a predetermined time around the circumference of a rotor yoke; a process of applying a second adhesive that is a thermosetting adhesive that requires a longer solidification time than the first adhesive but has higher adhesive strength to the adhesive surfaces of plate-shaped magnets that are divided into a plurality of flat plates; a process of installing positioning members around the circumference of the rotor yoke, the positioning members being formed by linking annularly comb-tooth-shaped partition members that position the plate-shaped magnets in the radial and axial directions; a process of positioning the plate-shaped magnets between the partition members of the rotor yoke on which the positioning members are installed, and arranging the plate-shaped magnets at predetermined intervals in the radial and axial directions between the partition members of the rotor yoke, and forming a gap between the curved surface of the rotor yoke and the flat surface of the plate-shaped magnets as an adhesive storage portion, and applying the first adhesive and the second adhesive; a process of solidifying the first adhesive and forming partition portions that separate the plate-shaped magnets in the circumferential direction, and partially adhering the plate-shaped magnets to the rotor yoke and positioning them in the radial and axial directions at the first adhesive portions; a process of removing the positioning members from the rotor yoke; and a process of solidifying the second adhesive and adhering the plate-shaped magnets to the rotor yoke at the first adhesive portions and the second adhesive portions.

[0032] In addition, the first adhesive and the second adhesive applied to the adhesive surfaces of the plate-shaped magnets include both cases of being applied directly to the adhesive surfaces and cases of being supplied to the adhesive surfaces in advance and being applied indirectly. When referred to as a plate-shaped magnet, it is a plate material having a certain thickness, and is not limited to a flat plate, but also includes various forms such as a curved plate.

[0033] According to the manufacturing method of the rotor described above, since the first adhesive is applied around the circumference of the rotor yoke using a plurality of adhesives having different solidification conditions, and the second adhesive is applied to the plate-shaped magnets, the adhesives having different solidification conditions are easily handled, and the application can be performed with high work efficiency.

[0034] In addition, by installing the positioning members that are annularly linked by comb-tooth-shaped partition members that position in the radial and axial directions on the rotor yoke, the plate-shaped magnets can be positioned and arranged in the radial and axial directions between the partition members.

[0035] Further, when the first adhesive is cured, a partition portion (first adhesive cured portion) partitioning the plate-shaped magnets is formed, the plate-shaped magnets are positioned with respect to the rotor yoke in the circumferential direction and the axial direction, and are partially adhered at the first adhesive portion. In this state, the positioning member can be removed from the rotor yoke, and the positioning member that is not originally needed can be omitted, the number of components can be reduced, the manufacturing cost can be reduced, and the weight of the rotor can be reduced.

[0036] Further, after the positioning member is removed from the rotor yoke, the second adhesive applied to the plate-shaped magnets is thermally cured and adhered and fixed with respect to the rotor yoke at the first adhesive portion and the second adhesive portion, and thus the plate-shaped magnets can be adhered and fixed with high positional accuracy.

[0037] In particular, the gap portion formed between the flat surface of the plate-shaped magnet and the curved surface of the adhesive surface of the rotor yoke can be used as an adhesive storage portion of the first adhesive and the second adhesive and as a sufficient adhesive space, and thus the adhesive strength of the first adhesive portion and the second adhesive portion can be maintained.

[0038] The manufacturing method of the rotor of the outer rotor type motor can include a process of installing a positioning member on the inner circumferential surface of the cylindrical rotor yoke, the positioning member being formed by linking comb-shaped partition members that position the plate-shaped magnets in the radial direction and the axial direction to a ring-shaped linking portion; a process of inserting a plurality of the plate-shaped magnets between the partition members and positioning the plate-shaped magnets on the inner circumferential surface of the rotor yoke at a predetermined interval via the first adhesive and the second adhesive; and a process of integrally assembling a rotor hub and a rotor shaft to the rotor yoke.

[0039] Alternatively, the manufacturing method of the rotor of the inner rotor type motor can include a process of installing a positioning member formed by linking comb-shaped partition members that position the plate-shaped magnets in the radial direction and the axial direction to a ring-shaped linking portion on the outer circumferential surface of the rotor yoke centered on a rotor shaft; and a process of inserting a plurality of the plate-shaped magnets between the partition members and positioning the plate-shaped magnets on the outer circumferential surface of the rotor yoke at a predetermined interval via the first adhesive and the second adhesive.

[0040] The first adhesive can use an ultraviolet-curable adhesive or a combination of an ultraviolet-curable adhesive and an anaerobic-curable adhesive, and the plate-shaped magnets can be partially adhered with respect to the rotor yoke.

[0041] Accordingly, by irradiating ultraviolet rays only to the first adhesive layer interposed between the plate-shaped magnets and between the plate-shaped magnets and the rotor yoke, the first adhesive can be cured in a short time, a partition portion (first adhesive cured portion) partitioning the plate-shaped magnets is formed, and thus the plate-shaped magnets can be easily partially adhered with respect to the rotor yoke.

[0042] Also, the plurality of plate magnets can be magnetized before being bonded in the rotor yoke or after being bonded in the rotor yoke.

[0043] If the plate magnets are magnetized in advance, they can be attracted to and adhere to each other when being inserted into the rotor yoke, but such an undesirable situation does not occur by using the positioning member.

[0044] In addition, if the plate magnets are magnetized after being bonded in the rotor yoke, the assembly work of the plate magnets becomes easy, and it is also difficult to be affected by thermal demagnetization.

[0045] Effects of Invention

[0046] As described above, a rotor that reduces the number of components, reduces manufacturing costs, and realizes weight reduction can be provided.

[0047] In addition, a manufacturing method of a rotor that can position a plurality of plate magnets in the radial and axial directions and bond and fix them to a rotor yoke with high positional accuracy, and that has good assembly, can be provided.

[0048] In addition, a motor that uses the above rotor, is inexpensive and has good assembly, and can maintain motor characteristics, can be provided. BRIEF DESCRIPTION OF DRAWINGS

[0049] Figures 1A-1E is an explanatory diagram showing a manufacturing process of a rotor of an outer rotor type motor.

[0050] Figures 2A-2D is an explanatory diagram showing a manufacturing process of an outer rotor type motor after FIG. 1.

[0051] Figures 3A1-3B3 is an explanatory diagram showing a form of a plate magnet that is bonded and fixed to a rotor yoke.

[0052] Figures 4A-4C is an explanatory diagram showing a manufacturing process of a rotor of an inner rotor type motor.

[0053] Figure 5A and Figure 5B is an explanatory diagram showing a bonding area of a first bonding portion and a second bonding portion of a plate magnet.

[0054] Figures 6A-6D is a process diagram showing a manufacturing method of a rotor of a conventional outer rotor type motor.

[0055] Figure 7A and Figure 7B is a process diagram showing a manufacturing method of a rotor of a conventional inner rotor type motor.

[0056] Figure 8A andFigure 8B This is an explanatory diagram showing the necessary structures of the rotor yoke and rotating hub. Detailed Implementation

[0057] Hereinafter, with reference to the accompanying drawings, an embodiment of the rotor, the rotor manufacturing method, and the motor of the present invention will be described. First, the schematic structure of the motor will be described with reference to FIG1. ​​In this embodiment, as an example of a motor, an external rotor type or an internal rotor type DC brushless motor described later is used.

[0058] like Figure 2C , Figure 2D As shown, the DC brushless motor uses an external rotor type motor M, comprising a rotor 1 and a stator 2. The rotor 1 is cup-shaped by being embedded in a rotor hub 4 connected to the rotor shaft 3, thereby closing one end opening of a cylindrical rotor yoke 5 (made of magnetic material such as iron or SUS). On the inner circumferential surface 5a of the rotor yoke 5 (refer to...) Figure 2A The rotor magnet (6) is attached to a plate-shaped magnet 6, which is alternately magnetized into N or S poles along the circumference. (See reference) Figure 2B Each plate magnet 6 is arranged opposite to the stator pole teeth 7b of the stator core 7, which will be described later. Furthermore, when referred to as a plate magnet 6, it can be any magnetic plate material with a certain thickness, and is not limited to a flat plate (see [reference]). Figure 3B1 It also includes bent plates (see reference). Figure 3A1 (and other forms)

[0059] like Figure 2C As shown, the stator 2 has a stator core 7 assembled on the outer periphery of the bearing housing 2a. Multiple stator pole teeth 7b of the stator core 7 protrude radially outward from the annular core back 7a. The stator core 7 can be either a laminated core formed by stacking and stamping electromagnetic steel plates or a block core composed of magnetic metal blocks. The stator pole teeth 7b of the stator core 7 are surrounded by an insulator (insulated winding tube) 7c, and coils 7d are wound around the insulator 7c. The rotor 1 inserts the rotor shaft 3 into the bearing housing 2a of the stator 2, and the plate magnet 6 is assembled with the stator pole teeth 7b of the stator core 7 in a rotatable configuration (see reference). Figure 2D ).

[0060] Here, the structure of rotor 1 will be described in detail.

[0061] like Figure 3A3 , Figure 3B3As shown in FIG. 1, the plate-shaped magnets 6 are arranged at intervals in the circumferential direction on the inner circumferential surface 5a of the cylindrical rotor yoke 5. The plate-shaped magnets 6 are made of a rare earth magnet (e.g., a neodymium magnet) whose surface is subjected to rust-preventive treatment, and are bonded by the first adhesive 8a and the second adhesive 8b in the gaps between the rotor yoke 5 and the plate-shaped magnets 6. The plate-shaped magnets 6 are divided and fixed in the circumferential direction by the division portions (first adhesive cured portions) 8c. Thus, as described later, the plate-shaped magnets 6 of high output can be fixed without positional deviation with respect to the rotor yoke 5 using different types of adhesives.

[0062] As shown in FIG. 1, the plate-shaped magnets 6 are arranged at intervals in the circumferential direction on the inner circumferential surface 5a of the cylindrical rotor yoke 5. The plate-shaped magnets 6 are made of a rare earth magnet (e.g., a neodymium magnet) whose surface is subjected to rust-preventive treatment, and are bonded by the first adhesive 8a and the second adhesive 8b in the gaps between the rotor yoke 5 and the plate-shaped magnets 6. The plate-shaped magnets 6 are divided and fixed in the circumferential direction by the division portions (first adhesive cured portions) 8c. Thus, as described later, the plate-shaped magnets 6 of high output can be fixed without positional deviation with respect to the rotor yoke 5 using different types of adhesives. Figure 5A Figure 5B As shown in FIG. 1, the plate-shaped magnets 6 are arranged at intervals in the circumferential direction on the inner circumferential surface 5a of the cylindrical rotor yoke 5. The plate-shaped magnets 6 are made of a rare earth magnet (e.g., a neodymium magnet) whose surface is subjected to rust-preventive treatment, and are bonded by the first adhesive 8a and the second adhesive 8b in the gaps between the rotor yoke 5 and the plate-shaped magnets 6. The plate-shaped magnets 6 are divided and fixed in the circumferential direction by the division portions (first adhesive cured portions) 8c. Thus, as described later, the plate-shaped magnets 6 of high output can be fixed without positional deviation with respect to the rotor yoke 5 using different types of adhesives. Figure 3B3

[0063] As shown in FIG. 1, the plate-shaped magnets 6 are arranged at intervals in the circumferential direction on the inner circumferential surface 5a of the cylindrical rotor yoke 5. The plate-shaped magnets 6 are made of a rare earth magnet (e.g., a neodymium magnet) whose surface is subjected to rust-preventive treatment, and are bonded by the first adhesive 8a and the second adhesive 8b in the gaps between the rotor yoke 5 and the plate-shaped magnets 6. The plate-shaped magnets 6 are divided and fixed in the circumferential direction by the division portions (first adhesive cured portions) 8c. Thus, as described later, the plate-shaped magnets 6 of high output can be fixed without positional deviation with respect to the rotor yoke 5 using different types of adhesives. Figure 3B2 As shown in FIG. 1, the plate-shaped magnets 6 are arranged at intervals in the circumferential direction on the inner circumferential surface 5a of the cylindrical rotor yoke 5. The plate-shaped magnets 6 are made of a rare earth magnet (e.g., a neodymium magnet) whose surface is subjected to rust-preventive treatment, and are bonded by the first adhesive 8a and the second adhesive 8b in the gaps between the rotor yoke 5 and the plate-shaped magnets 6. The plate-shaped magnets 6 are divided and fixed in the circumferential direction by the division portions (first adhesive cured portions) 8c. Thus, as described later, the plate-shaped magnets 6 of high output can be fixed without positional deviation with respect to the rotor yoke 5 using different types of adhesives.

[0064] As shown in FIG. 1, the plate-shaped magnets 6 are arranged at intervals in the circumferential direction on the inner circumferential surface 5a of the cylindrical rotor yoke 5. The plate-shaped magnets 6 are made of a rare earth magnet (e.g., a neodymium magnet) whose surface is subjected to rust-preventive treatment, and are bonded by the first adhesive 8a and the second adhesive 8b in the gaps between the rotor yoke 5 and the plate-shaped magnets 6. The plate-shaped magnets 6 are divided and fixed in the circumferential direction by the division portions (first adhesive cured portions) 8c. Thus, as described later, the plate-shaped magnets 6 of high output can be fixed without positional deviation with respect to the rotor yoke 5 using different types of adhesives.​​Figure 5A 、 Figure 5B As shown in FIG. 6, it is desirable that the second adhesive portion 6b has the same area as the first adhesive portion 6a (refer to FIG. 6A) or a larger area than the first adhesive portion 6a (second adhesive portion 6b > first adhesive portion 6a) (refer to FIG. 6B) in the adhesive region formed in the adhesive surface 6c of the plate-shaped magnet 6. Thereby, the adhesive strength of the plate-shaped magnet 6 with respect to the rotor yoke 5 can be maintained. Figure 5A ) or a larger area than the first adhesive portion 6a (second adhesive portion 6b > first adhesive portion 6a) (refer to Figure 5B ) in the adhesive region formed in the adhesive surface 6c of the plate-shaped magnet 6. Thereby, the adhesive strength of the plate-shaped magnet 6 with respect to the rotor yoke 5 can be maintained.

[0065] As described above, the first adhesive 8a uses a UV-curable adhesive or an adhesive made of a mixture of a UV-curable adhesive and an anaerobic-curable adhesive, and the second adhesive 8b uses a heat-curable epoxy-based adhesive. Thereby, by irradiating the first adhesive 8a sandwiched between the plate-shaped magnets 6 and between the plate-shaped magnet 6 and the rotor yoke 5 with UV rays, the first adhesive 8a is cured in a short time to form the partition portion 8c that separates the plate-shaped magnets 6 from each other, and thus the plate-shaped magnets 6 can be easily partially adhered with respect to the rotor yoke 5. Further, when the second adhesive 8b is heat-cured, since the plate-shaped magnets 6 are positioned in the circumferential direction by the partition portion 8c and are partially adhered by the first adhesive 8a, positional displacement does not occur.

[0066] Further, a case where the plate-shaped magnet 6 is a flat plate has been described, but as shown in FIG. 7, the adhesive surface 6c can be a curved plate having the same curvature as that of the rotor yoke 5. In this case, the adhesives 8a, 8b applied between the curved inner circumferential surface 5a of the rotor yoke 5 and the adhesive surface 6c of the plate-shaped magnet 6 are formed uniformly in the circumferential direction of the adhesive surface 6c as shown in FIG. 8. As shown in FIG. 9, the inner circumferential surface 5a of the rotor yoke 5 is coated with the first adhesive 8a for partial adhesion, and the plate-shaped magnet 6 is coated with the second adhesive 8b for adhesive fixation, as in the case of the flat plate-shaped magnet. The state where the plate-shaped magnet 6 is adhered to the inner circumferential surface 5a of the rotor yoke 5 is shown in FIG. 10. Figure 3A1 Figure 3A2 Further, a case where the plate-shaped magnet 6 is a flat plate has been described, but as shown in FIG. 7, the adhesive surface 6c can be a curved plate having the same curvature as that of the rotor yoke 5. In this case, the adhesives 8a, 8b applied between the curved inner circumferential surface 5a of the rotor yoke 5 and the adhesive surface 6c of the plate-shaped magnet 6 are formed uniformly in the circumferential direction of the adhesive surface 6c as shown in FIG. 8. As shown in FIG. 9, the inner circumferential surface 5a of the rotor yoke 5 is coated with the first adhesive 8a for partial adhesion, and the plate-shaped magnet 6 is coated with the second adhesive 8b for adhesive fixation, as in the case of the flat plate-shaped magnet. The state where the plate-shaped magnet 6 is adhered to the inner circumferential surface 5a of the rotor yoke 5 is shown in FIG. 10. Figure 1B Figure 3A3 Further, as shown in FIG. 11, in order to position and adhere the plurality of plate-shaped magnets 6 to the inner circumferential surface 5a of the rotor yoke 5, a positioning member 10 made of resin is used. The positioning member 10 is made of a resin molding material and includes a ring-shaped linking portion 10a linked in a ring shape and a plurality of partition members 10b formed in a comb shape rising from the ring-shaped linking portion 10a. The partition members 10b are spaced apart from each other by a distance equal to or slightly wider than the width dimension of the plate-shaped magnet 6. Further, a flange portion 10c for abutting and positioning against the open end of the rotor yoke 5 is provided extending radially outward from the ring-shaped linking portion 10a.

[0067] Further, as shown in FIG. 11, in order to position and adhere the plurality of plate-shaped magnets 6 to the inner circumferential surface 5a of the rotor yoke 5, a positioning member 10 made of resin is used. The positioning member 10 is made of a resin molding material and includes a ring-shaped linking portion 10a linked in a ring shape and a plurality of partition members 10b formed in a comb shape rising from the ring-shaped linking portion 10a. The partition members 10b are spaced apart from each other by a distance equal to or slightly wider than the width dimension of the plate-shaped magnet 6. Further, a flange portion 10c for abutting and positioning against the open end of the rotor yoke 5 is provided extending radially outward from the ring-shaped linking portion 10a. Figure 1C As shown in FIG. 12, the positioning member 10 is positioned on the inner circumferential surface 5a of the rotor yoke 5, and the plate-shaped magnets 6 are positioned in the circumferential direction by the partition members 10b of the positioning member 10. The first adhesive 8a for partial adhesion is applied to the inner circumferential surface 5a of the rotor yoke 5, and the second adhesive 8b for adhesive fixation is applied to the plate-shaped magnets 6. The state where the plate-shaped magnets 6 are adhered to the inner circumferential surface 5a of the rotor yoke 5 is shown in FIG. 13.

[0068] As shown in FIG. 14, the positioning member 10 is positioned on the inner circumferential surface 5a of the rotor yoke 5, and the plate-shaped magnets 6 are positioned in the circumferential direction by the partition members 10b of the positioning member 10. The first adhesive 8a for partial adhesion is applied to the inner circumferential surface 5a of the rotor yoke 5, and the second adhesive 8b for adhesive fixation is applied to the plate-shaped magnets 6. The state where the plate-shaped magnets 6 are adhered to the inner circumferential surface 5a of the rotor yoke 5 is shown in FIG. 15. Figure 1D ​​As shown, the positioning member 10 (separating member 10b) is inserted into the inner circumferential surface 5a from one end opening of the rotor yoke 5, and the plate magnet 6 is inserted into the space between the separating members 10b from the other end opening to be positioned on the inner circumferential surface 5a in the radial and axial directions.

[0069] At this time, since the plate-shaped magnet 6 is coated with a first adhesive 8a around the inner circumferential surface 5a of the rotor yoke 5, the plate-shaped magnet 6 is positioned and disposed on the rotor yoke 5 in both the radial and axial directions. When irradiated with ultraviolet light, the first adhesive 8a cures in a short time, thereby forming a partition 8c that separates the plate-shaped magnets 6. Therefore, the plate-shaped magnets 6 can be easily bonded to the rotor yoke 5.

[0070] In addition, such as Figure 1E As shown, with the plate magnet 6 partially bonded to the inner circumferential surface 5a of the rotor yoke 5, the unnecessary positioning member 10 can be pulled out and removed from the rotor yoke 5. After removing the positioning member 10 from the rotor yoke 5, the plate magnet 6 is bonded and fixed at the second bonding portion 6b by heating and curing an epoxy resin-based second adhesive 8b at, for example, 100° to 180°. During the heating and curing process, the viscosity of the second adhesive 8b temporarily decreases, but since the plate magnet 6 is circumferentially positioned by the partition portion 8c and partially bonded by the first adhesive 8a, the plate magnet 6 will not shift in position. Thus, the previously unnecessary positioning member 10 can be reduced, manufacturing costs can be lowered, and the rotor 1 can be made lighter.

[0071] Furthermore, since multiple plate magnets 6 are bonded and fixed to the rotor yoke 5 at specified intervals using positioning members 10, cost reduction can be achieved compared to annular magnets, and assembly can be performed with high radial and axial positioning accuracy of the plate magnets 6 relative to the rotor yoke 5 without positional shift.

[0072] In this way, a rotor 1 of an external rotor type motor can also be formed, in which multiple plate-shaped magnets 6 divided circumferentially are fixed at specified intervals on the inner circumferential surface 5a of the rotor yoke 5.

[0073] In addition, such as Figure 4A As shown, a positioning member 10 can also be used to position and bond multiple plate-shaped magnets 6 (bent plates) to the outer peripheral surface 5b of the rotor yoke 5 of the inner rotor type motor. The positioning member 10 is made of resin molding material and includes an annular connecting portion 10a connected in a ring and multiple separating members 10b formed in a comb-like manner from the annular connecting portion 10a. The flange portion 10c may also be omitted.

[0074] like Figure 4AAs shown, the partition members 10b of the positioning member 10 are fitted to the outer circumferential surface 5b from the axial one end side of the rotor yoke 5, and the annular linking portion 10a is abutted against and mounted to the one end surface of the rotor yoke 5. By inserting the plurality of plate-shaped magnets 6 from the other end surface side of the rotor yoke 5 between the partition members 10b, respectively, positioning in the radial and axial directions is performed.

[0075] At this time, as shown in Figure 4B Since the outer circumferential surface 5b of the rotor yoke 5 is surrounded and coated with the first adhesive 8a, the plate-shaped magnets 6 can be positioned and arranged in the rotor yoke 5. Upon irradiation of ultraviolet rays, the first adhesive 8a is cured in a relatively short time, thereby forming partition portions (first adhesive cured portions) 8c that separate the plate-shaped magnets 6. Thus, the plate-shaped magnets 6 can be easily partially adhered with respect to the rotor yoke 5. In a state where the plate-shaped magnets 6 are partially adhered, the unnecessary positioning member 10 can be pulled out and removed from the rotor yoke 5 as shown in Figure 4C Upon removal of the positioning member 10 from the rotor yoke 5, the plate-shaped magnets 6 are adhered and fixed at the first adhesive portions 6a and the second adhesive portions 6b by heating and curing the second adhesive 8b at, for example, 100° to 180°. In the heating and curing process, the viscosity of the second adhesive 8b temporarily decreases, but since the plate-shaped magnets 6 are positioned in the circumferential direction by the partition portions 8c and are partially adhered by the first adhesive 8a, the plate-shaped magnets 6 do not shift in position.

[0076] Thus, as shown in Figure 4C Thus, as shown in

[0077] According to the above structure of the rotor 1, compared to a ring-shaped magnet, cost reduction and weight reduction can be achieved, and the plate-shaped magnets 6 can be assembled with high positional accuracy in the radial and axial directions with respect to the rotor yoke 5, whether it is an outer rotor type or an inner rotor type.

[0078] In addition, in the motor M, by including any one of the above rotor 1 and a stator 2 having stator teeth 7b opposite the plate-shaped magnets 6 of the rotor 1, an outer rotor type motor or an inner rotor type motor that is inexpensive, lightweight, has good assembly, and can maintain motor characteristics can be provided.

[0079] Here, the manufacturing process of the rotor 1 of the outer rotor type motor will be described with reference to FIGS. 1 to 2. In Figure 1A the rotor shaft 3 is inserted into the center portion of the rotor hub 4 and assembled integrally. As shown in Figure 1BAs shown, a first adhesive 8a, which cures for a predetermined time, is applied around and around the inner circumferential surface 5a of the rotor yoke 5 corresponding to the first bonding portion 6a of the plate magnet 6 (see Figure 5). The first adhesive 8a is, for example, an ultraviolet-curing adhesive or an adhesive formed by mixing an ultraviolet-curing adhesive with an anaerobic-curing adhesive. Furthermore, a second adhesive 8b, which requires a longer curing time but has higher bonding strength than the first adhesive 8a, is applied to the second bonding portion 6b adjacent to the first bonding portion 6a of the plate magnet 6. The second adhesive 8b is, for example, a thermosetting epoxy resin adhesive.

[0080] like Figure 1B As shown, in the process of applying the first adhesive 8a and the second adhesive 8b, the first adhesive 8a is applied around the inner circumferential surface 5a corresponding to the first bonding portion 6a from one end of the rotor yoke 5, and the second adhesive 8b is applied linearly along the long side of the second bonding portion 6b of the plate magnet 6. This simplifies the handling of adhesives with different curing conditions and enables highly efficient application.

[0081] Next, as Figure 1C As shown, a positioning member 10 is installed on the inner circumferential surface 5a of the rotor yoke 5. The positioning member 10 is formed by connecting a comb-shaped partition member 10b, which positions the plate magnet 6 in the radial and axial directions, to the annular connecting portion 10a. The partition member 10b is inserted from the open side of the other end of the rotor yoke 5 until the flange portion 10c abuts against the open end.

[0082] Next, as Figure 1D As shown, plate-shaped magnets 6 are inserted from one open side between the partition members 10b of the rotor yoke 5, which is equipped with positioning members 10, and are arranged at a predetermined interval on the inner circumferential surface 5a of the rotor yoke 5 via the first adhesive 8a and the second adhesive 8b.

[0083] exist Figure 1D In this state, the first adhesive 8a applied to the plate magnet 6 is cured, and the plate magnet 6 is partially bonded to the rotor yoke 5 at the first bonding portion 6a. Specifically, when the first adhesive 8a is irradiated with ultraviolet light, the first adhesive 8a cures and forms a partition portion 8c that separates the plate magnets 6, thereby enabling the plate magnets 6 to be circumferentially positioned and partially bonded to the rotor yoke.

[0084] Furthermore, when the UV-curable adhesive and the anaerobic-curable adhesive are mixed, the first adhesive 8a is cured by UV irradiation on the adhesive at the end face of the plate magnet 6, thus isolating it from the external gas, thereby protecting the interior (the interior of the void 9: see reference). Figure 3B2 The adhesive becomes anaerobic and solidifies.

[0085] Next, asFigure 1E The unnecessary positioning member 10 is pulled out from the other end opening of the rotor yoke 5 to which the plate-shaped magnet 6 is partially adhered.

[0086] Next, as shown in Figure 2A , the rotor hub 4 and the rotor shaft 3 assembled in Figure 1A are inserted into one end opening of the rotor yoke 5 to be integrally assembled, thereby assembling the rotor 1. Figure 2B The state after the rotor 1 is assembled is shown.

[0087] Next, the second adhesive 8b of the epoxy resin type is heated and cured at a prescribed temperature in the range of 100°C to 180°C, and the plate-shaped magnet 6 is adhered and fixed to the inner peripheral surface of the rotor yoke 5 at the first adhesive portion 6a and the second adhesive portion 6b.

[0088] In addition, it can be either one of magnetization of the plurality of plate-shaped magnets 6 before being adhered to the inside of the rotor yoke 5 and magnetization after being adhered to the inside of the rotor yoke 5.

[0089] If the plate-shaped magnet 6 is magnetized in advance, it is possible to be attracted to and adsorbed to each other when being inserted into the rotor yoke 5, but by using the positioning member 10, such a bad situation does not occur. In addition, if magnetization is performed after the plate-shaped magnet 6 is adhered to the inner peripheral surface 5a of the rotor yoke 5, the assembly work of the plate-shaped magnet 6 becomes easy, and it is also difficult to be affected by thermal demagnetization.

[0090] By the above, the rotor 1 is manufactured and assembled to the stator 2, thereby manufacturing the motor M. Specifically, as shown in Figure 2C , the rotor 1 inserts the rotor shaft 3 into the bearing housing 2a of the stator 2 and is rotatably supported by a bearing not shown. The plate-shaped magnet 6 of the rotor yoke 5 is arranged opposite to the stator pole teeth 7b of the stator core 7 and is rotatably assembled. The motor M after the rotor 1 is assembled to the stator 2 is shown in Figure 2D .

[0091] In addition, in the case of the rotor 1 of the internal rotor type motor, as shown in Figure 4A , by only changing the face to which the first adhesive 8a is applied to the rotor yoke 5, the rotor 1 can be manufactured via the same process. That is, as shown in Figure 4A , the first adhesive 8a can be applied to the outer peripheral surface 5b of the rotor yoke 5 corresponding to the first adhesive portion 6a and the second adhesive 8b can be applied to the adhesive surface 6c corresponding to the second adhesive portion 6b of the plate-shaped magnet 6.

[0092] As shown in Figure 4AAs shown, a positioning member 10 is installed on the outer peripheral surface 5b of the rotor yoke 5, which is assembled into a column shape around the rotor shaft 3. The positioning member 10 is formed by connecting comb-shaped partition members 10b, which position the plate magnet 6 in the radial and axial directions, to the annular connecting portion 10. The partition members 10b are inserted in such a way that they fit along the outer peripheral surface 5b of the rotor yoke 5 until the annular connecting portion 10a abuts against the end face of the rotor yoke 5.

[0093] Next, as Figure 4B As shown, plate-shaped magnets 6 are inserted between the partition members 10b of the rotor yoke 5, which is equipped with positioning members 10, and are positioned on the outer peripheral surface 5b of the rotor yoke 5 via a first adhesive 8a and a second adhesive 8b, and arranged at a specified interval.

[0094] exist Figure 4B In the desired state, the first adhesive 8a is irradiated with ultraviolet light, causing it to cure and form partitions 8c that separate the plate-shaped magnets 6. This allows the plate-shaped magnets 6 to be bonded to the outer peripheral surface 5b of the rotor yoke 5 at the first bonding portion 6a. When the first adhesive 8a applied to the plate-shaped magnets 6 cures, the plate-shaped magnets 6 are bonded to the rotor yoke 5 at the first bonding portion 6a.

[0095] Next, as Figure 4C As shown, the rotor 1 is assembled by removing the unwanted positioning member 10 from the rotor yoke 5, which is partially bonded with the plate magnet 6.

[0096] Finally, the epoxy resin-based second adhesive 8b is heated and cured at a specified temperature of 100°C to 180°C, and the plate-shaped magnet 6 is bonded and fixed to the outer peripheral surface 5b of the rotor yoke 5 at the second adhesive portion 6b. Through the above process, the rotor 1 of the internal rotor type motor is manufactured.

[0097] Alternatively, it could be any one of multiple plate magnets 6 being magnetized before being bonded to the rotor yoke 5 and after being bonded to the rotor yoke 5.

[0098] According to the above-described manufacturing method of rotor 1, since the first adhesive 8a is coated around the circumferential surface of rotor yoke 5 and the second adhesive 8b is coated on plate magnet 6 respectively, the processing of adhesives with different curing conditions becomes easy and the coating can be carried out with high work efficiency.

[0099] In addition, by mounting a positioning member 10, which is formed by annularly connecting comb-shaped partition members 10b that are positioned in the radial and axial directions, on the rotor yoke 5, plate-shaped magnets 6 can be positioned and arranged in the radial and axial directions between the partition members 10b.

[0100] Further, when the first adhesive 8a is cured, a partition 8c that separates the plate-shaped magnets 6 and positions and partially adheres the plate-shaped magnets 6 in the circumferential direction with respect to the rotor yoke 5 can be formed. In this state, the positioning member 10 can be pulled out from the rotor yoke 5, and by omitting the positioning member 10 that is not originally needed, the number of components can be reduced, manufacturing costs can be reduced, and the rotor 1 can be made lightweight.

[0101] Further, after the positioning member 10 is removed from the rotor yoke 5, the second adhesive 8b applied to the plate-shaped magnets 6 is thermally cured and adhered and fixed with respect to the rotor yoke 5, and thus the plate-shaped magnets 6 can be adhered and fixed with high positional accuracy.

[0102] As described above, a rotor 1 that reduces the number of components, reduces manufacturing costs, and is lightweight can be provided. Further, a manufacturing method of a rotor that can position a plurality of plate-shaped magnets 6 in the radial and axial directions and adhere and fix the plate-shaped magnets 6 to a rotor yoke 5 with good assembly can be provided.

[0103] Further, a motor M that can use the above-described rotor 1, is inexpensive, has good assembly, and can maintain motor characteristics can be provided.

Claims

1. A rotor comprising, at a peripheral surface of a rotor yoke, flat plate-shaped magnets divided into a plurality in a circumferential direction at prescribed intervals, the flat plate-shaped magnets being rare-earth magnets whose surfaces are subjected to rust-preventive treatment, characterized in that: a first adhesive portion and a second adhesive portion are formed adjacently or partially coincidentally on an adhesive surface of the flat plate-shaped magnets using a plurality of adhesives different in curing conditions, the first adhesive portion being coated with a first adhesive which is a ultraviolet-curing adhesive or a combination of a ultraviolet-curing adhesive and an anaerobic-curing adhesive, around the peripheral surface of the rotor yoke, the second adhesive portion being coated with a second adhesive which is a heat-curing adhesive, more requiring a curing time than the first adhesive but higher in adhesive strength, an adhesive layer is formed in a gap portion formed between a curved surface of the rotor yoke and a flat plate surface of the flat plate-shaped magnets, as an adhesive storage portion of the first adhesive and the second adhesive, the plurality of flat plate-shaped magnets disposed at the peripheral surface of the rotor yoke are respectively formed with a partition portion separating the flat plate-shaped magnets from each other in the circumferential direction, by curing of the first adhesive included in the adhesive storage portion, and the plurality of flat plate-shaped magnets are partially adhered at the first adhesive portion and positioned in a radial direction and an axial direction, the plurality of flat plate-shaped magnets are separated from each other in the circumferential direction by the partition portion at prescribed intervals, by heat-curing of the second adhesive, and are adhered and fixed at the first adhesive portion and the second adhesive portion accordingly.

2. The rotor according to claim 1, characterized in that: the second adhesive portion has the same area as the first adhesive portion or a larger area than the first adhesive portion, with respect to areas of the first adhesive portion in which the first adhesive is coated and the second adhesive portion in which the second adhesive is coated, in the adhesive surface of the flat plate-shaped magnets.

3. The rotor according to claim 1 or 2, characterized in that: the rotor is a rotor of an outer rotor type motor in which the flat plate-shaped magnets divided into a plurality in the circumferential direction are fixed at prescribed intervals on an inner peripheral surface of the rotor yoke formed in a cup shape.

4. The rotor according to claim 1 or 2, characterized in that: the rotor is a rotor of an inner rotor type motor in which the flat plate-shaped magnets divided into a plurality in the circumferential direction are fixed at prescribed intervals on an outer peripheral surface of the rotor yoke formed in a cylindrical shape.

5. A motor, comprising: the rotor according to any one of claims 1 to 4; and a stator having stator teeth opposed to the flat plate-shaped magnets of the rotor.

6. A manufacturing method of a rotor, comprising: a step of coating a first adhesive which is a ultraviolet-curing adhesive or a combination of a ultraviolet-curing adhesive and an anaerobic-curing adhesive, around a peripheral surface of a rotor yoke, the first adhesive being cured at a prescribed time; and a step of coating a second adhesive which is a heat-curing adhesive, more requiring a curing time than the first adhesive but higher in adhesive strength, on an adhesive surface of flat plate-shaped magnets divided into a plurality, the flat plate-shaped magnets being rare-earth magnets whose surfaces are subjected to rust-preventive treatment. ​ ​ ​ ​ ​ The motor comprises: ​ ​ ​ ​ a step of installing positioning members on the circumferential surface of the rotor yoke, the positioning members being formed by annularly connecting comb-tooth-shaped partition members that position the flat plate-shaped magnets in the radial and axial directions; a step of positioning the flat plate-shaped magnets between the partition members of the rotor yoke on which the positioning members are installed, using the gap portions formed between the curved surface of the rotor yoke and the flat plate surface of the flat plate-shaped magnets as adhesive reservoirs, and arranging the flat plate-shaped magnets at a prescribed interval via the first adhesive and the second adhesive on the circumferential surface of the rotor yoke; a step of curing the first adhesive and forming partition portions that separate the flat plate-shaped magnets in the circumferential direction, and partially bonding the flat plate-shaped magnets to the rotor yoke at the first adhesive portions on which the first adhesive is applied to the adhesive surfaces of the flat plate-shaped magnets, to position the flat plate-shaped magnets in the radial and axial directions; a step of removing the positioning members from the rotor yoke; and a step of thermally curing the second adhesive and fixing the flat plate-shaped magnets to the rotor yoke at the second adhesive portions on which the second adhesive is applied to the adhesive surfaces of the flat plate-shaped magnets.

7. The manufacturing method of the rotor according to claim 6, wherein the rotor is a rotor of an external rotor type motor, and the manufacturing method of the rotor includes: a step of installing positioning members on the inner circumferential surface of the rotor yoke, the positioning members being formed by comb-tooth-shaped partition members that position the flat plate-shaped magnets in the radial and axial directions being connected to annular connection portions; a step of inserting a plurality of the flat plate-shaped magnets between the partition members and positioning the flat plate-shaped magnets at a prescribed interval via the first adhesive and the second adhesive on the inner circumferential surface of the rotor yoke; and a step of integrally assembling a rotor hub and a rotor shaft to the rotor yoke.

8. The manufacturing method of the rotor according to claim 6, wherein the rotor is a rotor of an internal rotor type motor, and the manufacturing method of the rotor includes: a step of installing positioning members on the outer circumferential surface of the rotor yoke centered on a rotor shaft, the positioning members being formed by comb-tooth-shaped partition members that position the flat plate-shaped magnets in the radial and axial directions being connected to annular connection portions; and a step of inserting a plurality of the flat plate-shaped magnets between the partition members and positioning the flat plate-shaped magnets at a prescribed interval via the first adhesive and the second adhesive on the outer circumferential surface of the rotor yoke.

9. The manufacturing method of the rotor according to any one of claims 6 to 8, wherein the plurality of flat plate-shaped magnets are magnetized before being bonded to the rotor yoke, or are magnetized after being bonded to the rotor yoke. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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