JP2003264963A - Rotor and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reliable rotor, together with its manufacturing method, in which no peeling or damage to a magnet piece occurs. <P>SOLUTION: The rotor 10 comprises a plurality of magnet pieces 20 arrayed in circumferential direction on an outer peripheral surface of rotor shafts 12 and 12 formed from a magnet body provided with the outer peripheral surface comprising a curved surface, and an adhesive layer 14 which secures the plurality of the magnet pieces 20 on the outer peripheral surface. The magnet piece 20 comprises a film 24 covering at least a part of the surface of R-Fe-B sintered magnet bodies 22 and 22. The sintered magnet body 22 has Young's modulus of 140-180×10<SP>9</SP>N/m<SP>2</SP>. The film 24 has Young's modulus of 20-120×10<SP>9</SP>N/m<SP>2</SP>, with thickness of 5-30 μm. The adhesive layer 14 has thickness of 20-120 μm and is formed between the film 24 and the outer peripheral surface. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor and a method for manufacturing the same, and more particularly, to a rotor in which a sintered magnet is fixed to a rotor shaft with an adhesive and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, there has been used a motor using a rotor in which an arcuate (also referred to as "arch" or "tile") magnet piece is bonded to the outer peripheral surface of a rotor shaft. Ferrite magnets and rare-earth / cobalt-based sintered magnets have been widely used as magnet pieces for rotors. -Rare earth / iron / boron-based sintered magnets (hereinafter referred to as "R-Fe" that have better magnetic properties than cobalt-based sintered magnets
-B system sintered magnet ". R is a rare earth element including Y,
Fe is iron and B is boron. ) Is becoming widespread.

R-Fe-B system sintered magnets are mainly composed of R ₂ Fe.
_It is composed of a main phase composed of a ₁₄ B tetragonal compound, an R-rich phase composed of Nd and the like, and a B-rich phase. In addition,
A part of Fe may be replaced with a transition metal such as Co or Ni, and a part of B may be replaced with C. R-Fe-B based sintered magnets preferably used in the present invention are, for example, US Pat. No. 4,770,723 and US Pat. No. 4,79.
2,368.

However, with the progress of miniaturization and high performance of motors, miniaturization of magnets, in particular, the thickness of the magnets is rapidly reduced to 4 mm or less, and the division angle of the magnets is rapidly increased. (D in FIG. 1B) is large (for example, 85 ° or more) or high speed (for example, 4000).
Many things are rotating at more than rpm),
The problem that the magnet is peeled off or damaged from the rotor shaft is likely to occur.

This problem is caused by the rotor shaft (typically iron core).
This is remarkable when an R-Fe-B based sintered magnet having a smaller linear expansion coefficient than that of (1) is used, which is an obstacle to miniaturization and high performance of the motor. This is because the rotor shaft greatly expands / contracts when the magnet is adhered to the rotor shaft and hardened, or when the temperature changes during use, but the degree of change of the magnet is considerably smaller than that. Is.

Japanese Unexamined Patent Publication No. 8-154351 and Japanese Unexamined Patent Publication No. 8-154351
JP-A-223838 discloses a method of relieving stress generated between a rotor shaft and a magnet by using a soft adhesive (for example, a silicone-based adhesive) when bonding a cylindrical magnet to the rotor shaft. Is proposed.

[0007]

However, since the cylindrical magnet (radial ring) has a large internal stress that the magnet itself has, it is weaker in strength than the split type magnet and is damaged by high-speed rotation or the like. There are many. further,
Using a soft adhesive (for example, Young's modulus of about 30 MPa or less) as disclosed in the above publication, the thickness is 15
When a plurality of magnet pieces (divided permanent magnets) are bonded to the rotor shaft with an adhesive layer of 0 μm to 200 μm, the adhesive layer itself does not have sufficient strength. For example, when the rotor rotates at a high speed, the adhesive layer Cohesive failure may occur, causing a problem that the magnet pieces are peeled off or damaged.

Further, the silicone-based adhesives exemplified in the above publication generally have low heat resistance and a large decrease in adhesive strength at high temperatures, so that the temperature change during use is relatively large in industrial motors. It is difficult to apply to other uses.

The present invention has been made in view of the above points, and an object of the present invention is to provide a highly reliable rotor in which the magnet pieces are not peeled or damaged and a method for manufacturing the rotor.

[0010]

The rotor according to the present invention comprises:
The rotor shaft formed of a soft magnetic material having an outer peripheral surface formed of a curved surface, a plurality of magnet pieces arranged along the circumferential direction on the outer peripheral surface of the rotor shaft, and the plurality of magnet pieces A rotor including an adhesive layer fixed to an outer peripheral surface, wherein the magnet pieces (typically each of the plurality of magnet pieces) are an R—Fe—B based sintered magnet body and the sintered body. A coating that covers at least a portion of the surface of the magnet body, the sintered magnet body has a Young's modulus in the range of 140 to 180 × 10 ⁹ N / m ² , and the coating is 20 to 120 ×. 10 ⁹ N / m ²
And a thickness of 5 μm or more and 30 μm or less, and the adhesive layer has a thickness of 20 μm or more and 120 μm or more.
It is characterized by having a thickness of less than or equal to μm and being formed between the coating film and the outer peripheral surface, whereby the above object is achieved.

In one embodiment, the magnet pieces are arcuate magnets, and when the thickness of the arcuate magnet is t (mm) and the chord width dimension is W (mm), the division angle corresponding to each arcuate magnet is D (degree) is D ≧ 700 × (t / W) −30
Satisfy the relationship.

The T-peel strength of the adhesive layer is 6 N / m.
It is preferably m or more, and more preferably 7 N / mm or more.

In one embodiment, the soft magnetic material is
It contains Fe as a main component and has a linear expansion coefficient of 0.10 × 10 ⁻⁴ / K or more and 0.15 × 10 ⁻⁴ / K or less.

Fe in the sintered magnet body may be replaced by 0.3 to 5.0 mass% of Co based on the total mass of the sintered magnet body.

The coating preferably contains at least Al or Zn.

A motor according to the present invention comprises any of the above rotors.

A method of manufacturing a rotor according to the present invention includes a rotor shaft formed of a soft magnetic material having an outer peripheral surface formed of a curved surface, and a plurality of rotor shafts arranged on the outer peripheral surface of the rotor shaft in the circumferential direction. A magnet piece and a method of manufacturing a rotor comprising an adhesive layer for fixing the plurality of magnet pieces to the outer peripheral surface, the step of preparing the rotor shaft, and the plurality of magnet pieces, A sintered magnet body of R-Fe-B system having a Young's modulus of 140 to 180 × 10 ⁹ N / m ² .
The surface of the sintered magnet body is covered with 20 to 120 × 10 ⁹ N
Young's modulus in the range of / m ² and 5 μm or more and 30
a step of preparing a plurality of magnet pieces having a coating having a thickness of less than or equal to μm;
The step of fixing with an adhesive layer having a thickness of not less than μm and not more than 120 μm is included, whereby the above object is achieved.

In one embodiment, the step of fixing the plurality of magnet pieces with the adhesive preferably includes a heating step.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a rotor and a method for manufacturing the same according to the present invention will be described with reference to the drawings, but the present invention is not limited thereto.

1 (a) and 1 (b) schematically show a rotor 10 according to an embodiment of the present invention. Further, FIG. 2 shows a schematic enlarged cross-sectional view of the bonded portion of the rotor 10.

As shown in FIGS. 1 (a) and 1 (b),
The rotor 10 includes a rotor shaft 12 formed of a soft magnetic material having an outer peripheral surface formed of a curved surface, a plurality of magnet pieces 20 arranged along the circumferential direction on the outer peripheral surface of the rotor shaft 12, and a plurality of magnet pieces 20. The adhesive layer 14 for fixing the magnet piece 20 to the outer peripheral surface is provided. The rotor 10 is a rotor having a so-called split magnet, and the magnet piece 20 has a split angle of about 90 ° (D in FIG. 1B) with respect to the rotation axis and is symmetrical with respect to the rotation axis. It is arranged.

The rotor shaft (sometimes called a yoke) 12 is typically an iron core or a laminated steel plate, and soft magnetic such as an alloy (silicon steel plate, carbon steel, etc.) containing Fe (iron) as a main component. Formed from the body. The linear expansion coefficient of an alloy containing iron as a main component, which is preferably used as a material for the rotor shaft 12, is 0.10 × 10 ⁻⁴ / K or more and 0.15 × 10 ⁻⁴ / K or more.
It is K or less.

The magnet piece 20 has an R—Fe—B based sintered magnet body 22 and a coating 24 that covers at least a part of the surface of the sintered magnet body 22. The sintered magnet body 22 is 140 to 18
It has a Young's modulus in the range of 0 × 10 ⁹ N / m ² and has the aforementioned US Pat. No. 4,770,723 and US Pat.
A sintered magnet having the composition described in the specification of No. 2,368 can be preferably used.

The coating film 24 formed on the surface of the sintered magnet body 22 has a Young's modulus in the range of 20 to 120 × 10 ⁹ N / m ² and a thickness of 5 μm or more and 30 μm or less. Specifically, the coating 24 is softer (having a lower Young's modulus) Al, Zn, or Sn than the material of the rotor shaft 12.
It is preferable to use metal materials (including alloys) such as Since these metal materials have a lower Young's modulus than Ni, which has been widely used as a material for the corrosion resistant coating, it has a large effect of relieving stress. Further, when an adhesive harder than a silicone adhesive is used, even when the stress (thermal stress) due to the difference in the coefficient of thermal expansion between the rotor and the magnet piece cannot be sufficiently relaxed by the adhesive layer alone, By forming the coating film 24 using such a metal material, the stress can be sufficiently relaxed. Furthermore, the coating 24 made of the above-mentioned metallic material has a higher adhesiveness than the Ni coating.
There is also an advantage that the adhesiveness with 4 is high. The Young's modulus, linear expansion coefficient and melting point of Al, Zn and Sn are
It is shown in Table 1 along with values for Fe, which is a typical rotor shaft material, and Ni, which is a typical coating material.

[0025]

[Table 1]

The R-Fe-B system sintered magnet has a low corrosion resistance because it contains a rare earth element, but the corrosion resistance reliability of the magnet piece 20 can be improved by forming the coating film 24 of the metal material. Together with the adhesive layer 14 and the magnet piece 22
It is possible to relieve the stress generated between and. The film 12 may be provided at least between the sintered magnet body 22 and the adhesive layer 14 for stress relaxation, but in order to improve the corrosion resistance reliability of the magnet piece 20, the sintered magnet body 22 is required. It is needless to say that it is preferable to form so as to cover the entire surface of the.

As a material for forming the coating film 24, a metal material containing Al or Zn is preferable, and among them, Al is preferable.
Is preferably used. As a method of forming the coating film 24 using Al, it is preferable to use a vacuum vapor deposition method (see, for example, Japanese Patent Application Laid-Open No. 2001-32062 by the applicant of the present application), and further it is described in Japanese Patent Application Laid-Open No. 2000-150216. It is preferable to apply such shot peening. As a method of forming the coating film 24 using Zn or Sn, a wet plating method or the like can be used.
Since Sn softens at a relatively low temperature, the rotor 1
It is used when the upper limit of the operating temperature of 0 is low.

If the thickness of the coating film 24 is thinner than 5 μm, the effect of providing the coating film 24 may not be sufficiently exerted. On the contrary, if it is thicker than 30 μm, it takes a long time to form the coating film, and the productivity is lowered. Therefore, it is not preferable from the viewpoint of mass productivity.

The adhesive layer 14 has a thickness of 20 μm or more and 120 μm or more.
It has the following thickness: If the thickness of the adhesive layer 14 is less than 20 μm, it is difficult to form a uniform adhesive layer 14 between the outer peripheral surface of the rotor shaft 12 and the bonding surface of the magnet piece 20, and it is possible to obtain a sufficient adhesive force. Have difficulty. On the other hand, the adhesive layer 1
When the thickness of No. 4 exceeds 120 μm, cohesive failure of the adhesive layer 14 easily occurs, and high speed (for example, 4000 rpm)
In the case where the magnet piece 20 is rotated, or in the case of reciprocating compressor such as reciprocating compressor, peeling or damage of the magnet piece 20 is likely to occur. Adhesive layer 14
More preferably, the thickness is set in the range of 40 μm or more and 80 μm or less. Furthermore, if the tensile shear adhesive strength (JISK 6850: 1999) of the adhesive layer 14 is too low, cohesive failure is likely to occur prior to interfacial failure on the adhesive surface, so the adhesive layer 14 has a tensile shear adhesive strength of 2
The pressure is preferably 5 MPa or more, more preferably 30 MPa or more.

Further, the adhesive layer 14 is 6 N / mm or more 1
T-shaped peel strength of 6 N / mm or less (JISK6854-
3: 1999). As the adhesive, a thermosetting adhesive is preferable, and for example, an epoxy or acrylic adhesive can be used. Specifically, for example, SW-2214 manufactured by Sumitomo 3M Co., Ltd., XD-911 manufactured by Ciba-Geigy Co., etc. can be preferably used. In order to obtain sufficient adhesive strength and from the viewpoint of heat resistance, it is preferable to use a thermosetting adhesive that is hardened near the upper limit of the operating temperature range of the rotor 10.

The magnet piece 2 in the rotor 10 according to the present invention
0 is the sintered magnet body 22 and 20 to 120 × 10 ⁹ N / m ²
And a coating film 24 having a Young's modulus in the range of 5 μm or more and 30 μm or less, and 20 μm or more and 12 μm or more.
The rotor shaft 12 has an adhesive layer 14 having a thickness of 0 μm or less.
Since it is bonded and fixed to the sintered magnet body 22,
R-F having Young's modulus in the range of 180 × 10 ⁹ N / m ²
Even in the case of the e-B system sintered magnet body, the magnet piece 20 is not peeled or damaged. For example, the coefficient of linear expansion in the direction perpendicular to the C axis shown in FIG. 2 is 0 to −0.005 × 10 ⁻⁴ / K.
Even in the case of the R-Fe-B system sintered magnet, the magnet piece 20 is prevented from being peeled off and the magnet piece 20 from being cracked.

Further, for the purpose of improving heat resistance and the like, Fe in the sintered magnet is replaced with 0.3 to 5.0% by mass of Co based on the total mass of the sintered magnet body. In this case, a compound of R and Co is formed at the grain boundaries of the sintered body, and the mechanical strength of the sintered body is reduced, so that cracks are likely to occur. However, by adopting the configuration of the present invention The generation of cracks can be effectively suppressed.

When the division angle D of the magnet piece 20 approaches 90 °, the stress applied to the magnet piece 10 increases, so the thickness of the arcuate magnet is t (mm) and the chord width dimension is W (mm). , The division angle D corresponding to each arcuate magnet
The effect of the present invention is remarkable when (degree) satisfies the relationship of D ≧ 700 × (t / W) −30, particularly when t is 4 mm or less.

Hereinafter, the advantages of the rotor 20 according to the embodiment of the present invention will be described in more detail with reference to experimental examples.

First, the material is SS41 (stainless steel)
Then, a cylindrical rotor shaft 12 having a diameter of 36.5 mm was prepared.

As the magnet piece 20, the division angle (D): 88
°, chord width (W): 28.7 mm, thickness (t): 3.5 m
m (700 × (t / W) −30 = 55.4) R—Fe
-B type sintered magnet (Sumitomo Special Metals Co., Ltd .: NEOMAX-3
5SH), aluminum coatings of various thicknesses formed by vacuum vapor deposition were used. The vacuum evaporation method is disclosed in
The method described in Japanese Patent Publication 1-32062, and
Shot peening as shown in JP-A-2000-150216 was performed.

For the adhesive layer 14, thermosetting adhesives A and B were used. Adhesives A and B are both Sumitomo 3M
It is an epoxy adhesive manufactured by the company. The curing temperature is 100 to
It was 140 ° C. After curing, it was left to cool to room temperature. The adhesive A had a T-shaped peel strength of 9 N / mm, and the adhesive B had a T-shaped peel strength of 3.9 N / mm. The T-shaped peel strength was measured by a method according to JIS K6854-3: 1999.

The magnet pieces 20 having different thicknesses of the aluminum coating 24 were bonded to the rotor shaft while changing the thickness of the adhesive layer 14 to prepare a sample rotor, and the bonding reliability was evaluated.
After the heat curing treatment, the sample rotor is set to 4000 rp.
After rotating for 12 hours at m, the occurrence of defective adhesion was visually evaluated. The number of sample rotors was 10, respectively.

In the sample rotor using the adhesive B, peeling and cracking of the magnet pieces occurred as shown in Table 2 below, while in the sample rotor using the adhesive A, any sample was used. Also, no peeling or cracking occurred.

[0040]

[Table 2]

As can be seen from this, the adhesive layer 14
When the T-shaped peel strength of 3.9 N / mm, sufficient adhesive strength may not be obtained. As a result of various studies, the adhesive layer 1
It was found that the T-shaped peel strength of No. 4 is preferably 6 N / mm or more. Of course, it is more preferable to use the adhesive layer 14 having a T-shaped peel strength of 8 N / mm or more as in the case of using the adhesive A.

Tables 3 and 4 show the results of measuring the adhesive strength of each sample rotor.
Table 3 shows the results when Adhesive A was used, and Table 4 shows the results when Adhesive B was used. In addition, Table 4 shows the results of measurement for samples in which neither peeling nor cracking occurred.

The tensile shear strength in each table is
⊚ indicates 29.4 MPa or more, and ∘ indicates 19.6 MP.
a or higher, △ indicates 9.8 MPa or higher, x indicates 0.98M
It shows Pa or more and less than 9.8 MPa.

[0044]

[Table 3]

[0045]

[Table 4]

As can be seen from Tables 3 and 4, no matter which of the adhesives A and B was used, when the thickness of the adhesive layer 14 exceeds 120 μm, the adhesive strength is lowered. As a result of observing the fracture state after measuring the adhesive strength,
In these samples, it was confirmed that cohesive failure of the adhesive layer 14 had occurred. As a result of various studies, when the thickness of the adhesive layer 14 exceeds 120 μm, cohesive failure is more likely to occur than interface failure, so it is considered preferable that the thickness of the adhesive layer 14 be 120 μm or less. Since it is difficult to form the adhesive layer 14 having a thickness less than 20 μm uniformly, workability is reduced, and adhesive strength is reduced, the thickness of the adhesive layer 14 is 20 μm or more. It is preferable.

Further, as shown in the experimental example, if the thickness of the aluminum coating 24 is in the range of 5 μm or more and 30 μm or less,
By setting the thickness of the adhesive layer 14 to 20 μm or more and 120 μm or less, the rotor 10 having high reliability can be obtained. When the aluminum coating 24 is not provided, the magnet pieces may be peeled off or damaged even when the adhesive A is used, and the iron-based alloy as the material of the rotor shaft 12 or the conventional coating material is used. It has been found that it is preferable to use a metal material having a Young's modulus lower than that of Ni. As a result of various studies, the Young's modulus of the material of the coating film 24 is 20 to 12
It was considered preferable to be in the range of 0 × 10 ⁹ N / m ² .

In the experimental example described above, the coating film 24 is formed by using Al.
However, the same effect can be obtained by forming a film using Zn. Zn has an advantage that it is cheaper than Al.

[0049]

According to the present invention, since the magnet piece formed of the R—Fe—B system sintered magnet body can be adhered to the rotor shaft in a good condition, the magnet piece is highly reliable without peeling or damage. A rotor and a method for manufacturing the same are provided. The present invention is particularly preferably applied to a rotor that rotates at a high speed (for example, 4000 rpm or more) and a rotor that repeatedly performs reversal operation such as a reciprocating compressor, and can reduce the size and performance of a motor.

[Brief description of drawings]

1A and 1B are diagrams schematically showing a rotor 10 according to an embodiment of the present invention, where FIG. 1A is a perspective view and FIG. 1B is a sectional view.

FIG. 2 is a schematic enlarged cross-sectional view of a bonded portion of the rotor 10 according to the embodiment of the present invention.

[Explanation of symbols]

10 rotor 10 12 rotor shaft 14 Adhesive layer 20 magnet pieces

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 5H002 AA08 AB01 AB07 AC04 AE07                       AE08                 5H622 CA02 CA05 CA13 CB04 CB05                       DD01 DD02 PP01 PP03 PP07                       PP19 QA02 QA08

Claims (9)

[Claims] 1. A rotor shaft formed of a soft magnetic material having an outer peripheral surface formed of a curved surface, a plurality of magnet pieces arranged circumferentially on the outer peripheral surface of the rotor shaft, and the plurality of magnet pieces. A magnet layer for fixing the magnet piece to the outer peripheral surface, wherein the magnet piece is an R—Fe—B based sintered magnet body and at least a part of the surface of the sintered magnet body. The sintered magnet body has a Young's modulus in the range of 140 to 180 × 10 ⁹ N / m ² , and the coating has a thickness of 20 to 120 × 10.
Young's modulus in the range of ⁹ N / m ² and 5 μm or more 3
The rotor has a thickness of 0 μm or less, the adhesive layer has a thickness of 20 μm or more and 120 μm or less, and is formed between the coating film and the outer peripheral surface. 2. The magnet piece is an arcuate magnet, and when the thickness of the arcuate magnet is t (mm) and the chord width dimension is W (mm), the division angle D (degrees corresponding to each arcuate magnet is )
Satisfies the relationship of D ≧ 700 × (t / W) −30,
The rotor according to claim 1. 3. The T-shaped peel strength of the adhesive layer is 6 N /
The rotor according to claim 1 or 2, which has a thickness of at least mm. 4. The soft magnetic material contains Fe as a main component and has a linear expansion coefficient of 0.10 × 10 ⁻⁴ / K or more and 0.15 × 10 ⁻⁴ / K or less. The rotor according to any one. 5. The Fe in the sintered magnet body is replaced by 0.3 to 5.0 mass% of Co based on the total mass of the sintered magnet body. The rotor described in. 6. The rotor according to claim 1, wherein the coating film contains at least Al or Zn. 7. A motor comprising the rotor according to claim 1. Description: 8. A rotor shaft formed of a soft magnetic material having an outer peripheral surface formed of a curved surface, a plurality of magnet pieces arranged circumferentially on the outer peripheral surface of the rotor shaft, and the magnet. A method of manufacturing a rotor, comprising: an adhesive layer for fixing a piece to the outer peripheral surface; a step of preparing the rotor shaft having the outer peripheral surface; and a plurality of magnet pieces, each of which is 140 to 180. × 1
An R-Fe-B based sintered magnet body having a Young's modulus in the range of 0 ⁹ N / m ² , and at least a part of the surface of the sintered magnet body, covering 20 to 120 x 10 ⁹ N / m ² A step of preparing a plurality of magnet pieces having a Young's modulus in the range of 5 μm and a coating having a thickness of 5 μm or more and 30 μm or less; and the coating and the outer peripheral surface of each of the plurality of magnet pieces. A step of fixing the plurality of magnet pieces to the rotor shaft by forming an adhesive layer having a thickness of 20 μm or more and 120 μm or less between them; 9. The method of manufacturing a rotor according to claim 8, wherein the step of fixing the plurality of magnet pieces includes a heating step.