JP2005012047A - Hysteresis bond magnet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hysteresis bond magnet advantageous for a hysteresis generating device such as a torque limiter excellent in cost performance and safety. <P>SOLUTION: This hysteresis bond magnet is constituted of oxide magnetic powder 75 to 95 wt.% whose coercive force is 100 to 1,100 Oe (8.0 to 87.6 KA/m), whose mean particle diameter is 0.5 μm or larger, and whose compression density is 2.7 to 3.5 g/cm<SP>3</SP>and binder resin 25 to 5 wt.%. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a hysteresis bond magnet, and more particularly, to a hysteresis bond magnet that is inexpensive and excellent in safety and is useful for a torque limiter, a damper, a shock absorber, an accelerator pedal, and the like.
[0002]
[Prior art]
Conventionally, as this type of magnet, as shown in FIG. 6, a torque in which a sintered magnet 4 inserted through a shaft 3 is rotatably mounted in a cylindrical casing 2 in which a metal hysteresis plate 1 is stretched inside. Limiters are known (see, for example, Patent Document 1, page 4, FIG. 4).
[0003]
Also, 75 to 95% by weight of cast magnet powder, 3 to 20% by weight of resin binder, 0.1 to 5% by weight of slip agent, and 0.5 to 3% by weight of cup based on the total weight. A semi-rigid plastic magnet made of a ring agent and formed into a cylindrical shape has been proposed (see, for example, Patent Document 1, page 4, FIG. 1).
[0004]
[Patent Document 1]
Japanese Patent Laid-Open No. 2000-243613
[Problems to be solved by the invention]
However, since the former torque limiter requires the metal hysteresis plate 1, the number of parts and the number of assembling steps are increased, resulting in an increase in cost. Further, since the number of parts and the number of assembly steps increase, a dimensional error is likely to occur, and the clearance 5 between the hysteresis plate 1 and the sintered magnet 4 needs to be set large. Accordingly, not only does the hysteresis torque vary, but the size of the hysteresis 5 is inevitably increased by setting the clearance 5 larger, and it is difficult to satisfy the demand for downsizing.
[0006]
According to the latter semi-rigid plastic magnet, the above-mentioned problems can be solved, but since the cast magnet powder obtained by pulverizing the cast magnet is used, the particle size distribution is large, and the particle shape is sharp and uneven. Therefore, the fluidity at the time of melt molding is poor and molding is difficult, and problems such as short shots and weld lines occur. If the content of the cast magnet powder is reduced to improve the moldability, a new problem is caused that the magnetic properties are lowered. Furthermore, the energy consumption for pulverizing the cast magnet is large, which increases the cost.
[0007]
Furthermore, since the cast magnet powder contains expensive Co, Ni, etc., not only the cost increases, but Ni may cause, for example, blurring when touching the human body during the manufacturing process. Is included.
[0008]
In view of such circumstances, the present invention provides a hysteresis bond magnet that eliminates the drawbacks of the above prior art, is inexpensive and versatile, has excellent safety, and is highly versatile.
[0009]
[Means for Solving the Problems]
As a result of intensive studies to solve the above problems, the present inventors have found that a hysteresis bonded magnet using a specific oxide magnetic powder is inexpensive, versatile, and excellent in safety, and has reached the present invention. .
[0010]
That is, the invention according to claim 1 of the present invention has a coercive force of 100 to 1100 Oe (8.0 to 87.6 KA / m), an average particle size of 0.5 μm or more, and a compression density of 2.7 to 3. A hysteresis bond magnet comprising 75 to 95% by weight of oxide magnetic powder of 5 g / cm ³ and 25 to 5% by weight of a binder resin is included.
[0011]
The invention according to claim 2 of the present invention contains 0.1 to 5% by weight of a lubricant and 0.5 to 3% by weight of a coupling agent with respect to 100% by weight of the total of the oxide magnetic powder and the binder resin. The hysteresis bonded magnet according to claim 1 is included.
[0012]
The invention according to claim 3 of the present invention includes the hysteresis bonded magnet according to claim 1 or 2, wherein the oxide magnetic powder is oriented in the thickness direction.
[0013]
The invention according to claim 4 of the present invention includes the hysteresis bonded magnet according to any one of claims 1 to 3, wherein the working surface side is anisotropic in the thickness direction and the non-working surface side is isotropic. And
[0014]
The invention according to claim 5 of the present invention is the hysteresis according to any one of claims 1 to 4, wherein the working surface side is anisotropic in the thickness direction, and the ferromagnetic material is arranged on the non-working surface side. Includes bonded magnets.
[0015]
The invention according to claim 6 of the present invention includes the hysteresis bonded magnet according to any one of claims 1 to 5, which has a cylindrical shape or a disk shape.
[0016]
The invention according to claim 7 of the present invention is for a torque limiter, and includes the hysteresis bond magnet according to any one of claims 1 to 6.
[0017]
In the present invention, the hysteresis bonded magnet refers to a bonded magnet used in a hysteresis generator required for a torque limiter, a damper, a shock absorber, a clutch, an accelerator pedal, and the like.
[0018]
[Action]
The hysteresis bonded magnet of the present invention has a coercive force of 100 to 1100 Oe (8.0 to 87.6 KA / m), an average particle size of 0.5 μm or more, and a compression density of 2.7 to 3.5 g / cm ³ . It consists of 75 to 95% by weight of certain oxide magnetic powder and 25 to 5% by weight of binder resin. Compared to cast magnet powder using expensive Co or Ni, Ni that has a safety problem, etc. Therefore, it is possible to provide a hysteresis bond magnet that is inexpensive, safe, and versatile.
[0019]
Also, since the oxide magnetic powder is oriented in the thickness direction, a bonded magnet having a large hysteresis torque is obtained, and the working surface side is made anisotropic in the thickness direction, and the non-working surface is made isotropic. By this, it becomes a closed loop and a hysteresis torque can be increased. Furthermore, by providing a ferromagnetic material on the non-working surface side, a closed loop is formed by the back yoke effect of the ferromagnetic material, and the hysteresis torque can be greatly increased.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
The oxide magnetic powder in the present invention has a coercive force of 100 to 1100 Oe (8.0 to 87.6 KA / m), an average particle size of 0.5 μm or more, and a compression density of 2.7 to 3.5 g / cm. ^Three are used.
[0021]
The coercive force depends on the residual magnetism such as the permanent magnet used together, and thus it is difficult to define it generally. However, generally, when the coercive force is less than 100 Oe (8.0 KA / m), it is used for a torque limiter, for example. However, if it exceeds 1100 Oe (87.6 KA / m), cogging occurs when the residual magnetism of the magnet used together with the hysteresis bonded magnet is small, for example. In some cases, there is a tendency that a smooth hysteresis torque cannot be obtained.
[0022]
When the average particle size of the oxide magnetic powder is less than 0.5 μm, it is difficult to set the compression density to 2.7 to 3.5 g / cm ³ . The upper limit of the average particle diameter is a range where the coercive force does not become less than 100 Oe (8.0 KA / m), and is usually about 5 μm.
[0023]
When the compression density of the oxide magnetic powder is less than 2.7 g / cm ³ , the residual magnetism is not sufficiently increased. On the other hand, when it exceeds 3.5 g / cm ³ , the fluidity at the time of melt molding is lowered and the moldability tends to be impaired. This can be dealt with, for example, by increasing the fine powder of around 0.2 μm, but in this case, the specific surface area of the magnetic powder becomes too large, and the fluidity at the time of melting the composition with the binder resin tends to deteriorate. . The residual magnetism is preferably 1,500 G (150 mT) or more, and the upper limit is not particularly limited, but is preferably about 3,000 G (300 mT) industrially.
[0024]
As the above oxide magnetic powder, magnetoplumbite type strontium ferrite, barium ferrite and the like are preferable, and magnetite, Y-phase ferrite and the like can also be used. These may be used alone or in combination of two or more as required.
[0025]
Examples of the binder resin used in the present invention include polyamide resins such as polyamide 6, polyamide 12, polyamide 66, aromatic polyamide containing an aromatic ring; polyvinyl chloride resin, vinyl chloride-vinyl acetate copolymer resin, poly Polyolefin resins obtained by singly or copolymerizing methyl methacrylate resin, polystyrene resin, polyethylene and polypropylene; polyurethane resins, silicone resins, polycarbonate resins, polybutylene terephthalate (PBT), polyester resins such as polyethylene terephthalate (PET), polyether ethers Ketone (PEEK) resin, polyphenylene sulfide (PPS) resin, chlorinated polyethylene (CPE) resin, chlorosulfonated polyethylene resin (trade name “Hypalon” from DuPont) ), Acrylonitrile-butadiene-styrene (ABS) resin, liquid crystal resin, epoxy resin, phenol resin, etc .; rubber such as isoprene, neoprene, styrene butadiene, butadiene, acrylonitrile butadiene; olefin ethylene-propylene-diene-methylene (EPDM) ), Urethane-based, polyester-based elastomers, and the like can be used, and these can be used alone or in admixture of two or more. Among these, polyamide resin, ABS resin, polyvinyl chloride resin, PPS resin, liquid crystal resin, and elastomer are preferable.
[0026]
The hysteresis bonded magnet of the present invention comprises 75 to 95% by weight of oxide magnetic powder and 25 to 5% by weight of binder resin. If the oxide magnetic powder is less than 75% by weight, a hysteresis torque that can withstand practical use cannot be obtained. On the other hand, if it exceeds 95% by weight, the fluidity at the time of molding deteriorates, and a weld line is generated in the molded product, resulting in mechanical strength. Of the magnetic powder or the orientation of the magnetic powder is lowered, and a sufficient hysteresis torque cannot be obtained.
[0027]
The hysteresis bonded magnet of the present invention can contain a lubricant and a coupling agent as required.
As lubricants, fatty acid salts such as lead stearate, calcium stearate, barium stearate, magnesium stearate, calcium laurate, zinc linoleate, fatty acids such as stearic acid, lauric acid, palmitic acid, oleic acid, paraffin wax, fluid Examples include waxes such as paraffin, polyethylene wax, polypropylene wax and carnauba, and these are used alone or in combination as necessary.
[0028]
As the coupling agent, vinyltrichlorosilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, N-β (aminoethyl) ) Silanes such as γ-aminopropyltrimethoxysilane, N-β (aminoethyl) γ-aminopropylmethyldimethoxysilane, γ-chloropropyltrimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane Coupling agent, isopropyltriisostearoyl titanate, isopropyltri (N-aminoethyl) titanate, isopropyltris (dioctylpyrophosphate) titanate, tetraisopropylbis (dioctylphosphine) Ito) titanate, tetraisopropyl titanate, tetrabutyl titanate, tetraoctyl bis (ditridecyl phosphite) titanate, isopropyl trioctanoyl titanate, isopropyl tridodecylbenzenesulfonyl titanate, isopropyl tri (dioctyl phosphate) titanate, bis (dioctyl pyrophosphate) Ethylene titanate, isopropyl dimethacrylisostearoyl titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl phosphite) titanate, isopropyl tricumyl phenyl titanate, bis (dioctylpyrophosphate) oxyacetate titanate, isopropyl Titanate coupling agents such as isostearoyl diacryl titanate These are selected according to the kind of magnetic powder and the kind of binder resin, and are used alone or in combination as necessary.
[0029]
The lubricant is usually used in an amount of 0.1 to 5% by weight based on 100% by weight of the total of the oxide magnetic powder and the binder resin. If the lubricant is less than 0.1% by weight, it may be difficult to release from the mold, resulting in decreased productivity and increased cost, or the surface of the molded product may be removed at the time of release. In this case, the mechanical strength and hysteresis torque may be reduced from the portion. On the other hand, if it exceeds 5% by weight, bleeding from the surface of the molded product may be caused or mechanical strength may be lowered.
[0030]
The coupling agent is usually used in an amount of 0.5 to 3% by weight based on 100% by weight of the total of the oxide magnetic powder and the binder resin. If the coupling agent is less than 0.5% by weight, the effect of addition may not be sufficiently obtained. On the other hand, if it exceeds 3% by weight, foaming occurs due to thermal decomposition during molding, resulting in a decrease in mechanical strength. There is a case.
[0031]
The hysteresis bond resin of the present invention may further contain a commonly used plasticizer, antioxidant, stabilizer and the like.
[0032]
The hysteresis bond magnet of the present invention is formed into a cylindrical shape, a disk shape, or the like by injection molding, extrusion molding or the like from the resin composition as described above. In the hysteresis bond magnet of the present invention, the magnetic powder is preferably oriented in the thickness direction. In this case, the working surface side is anisotropic in the thickness direction, and the non-working surface side on the opposite side is made isotropic, so that the isotropic opposite surface side serves as a back yoke to increase the magnetic field. In addition, the hysteresis torque can be increased. Furthermore, the working surface side of the hysteresis bonded magnet is anisotropy in the thickness direction, and a ferromagnetic material such as an iron plate is disposed on the non-working surface side opposite to the hysteresis surface, thereby providing hysteresis due to the back yoke effect of the ferromagnetic material. Torque can be increased.
[0033]
The hysteresis bond magnet of the present invention obtained as described above is useful for hysteresis generators such as torque limiters, dampers, shock absorbers, clutches, accelerator pedals and the like.
[0034]
As a magnet used with the hysteresis bonded magnet of the present invention, a permanent magnet is usually used, and either a sintered magnet or a bonded magnet may be used. However, since the sintered magnet is inferior in dimensional accuracy as it is, it is necessary to set a large clearance with the hysteresis bond magnet. Therefore, not only does the hysteresis torque vary, but also the clearance is set large. It is inevitable that the size will increase by the amount, and it is difficult to satisfy the demand for miniaturization. This problem can be solved by polishing the sintered magnet to increase the dimensional accuracy. However, since a separate polishing step is required, the cost increases accordingly. There is also a drawback that cracks and chips are likely to occur.
On the other hand, the bonded magnet is suitable in that it does not have the above-described problems, is excellent in moldability and dimensional accuracy, and is less likely to be cracked or chipped.
[0035]
In addition to the above-mentioned ferrite magnetic powder, rare earth magnetic powder such as samarium-cobalt magnetic powder, neodymium-iron-boron magnetic powder, samarium-iron-nitrogen magnetic powder, etc. Conventionally known anisotropic permanent magnetic powders can be used, and these can be used alone or in combination of two or more if necessary. The same binder resin as the above-described hysteresis bond magnet is used. The blending ratio is preferably 40 to 70% by volume for magnetic powder and 60 to 30% by volume for binder resin. If the magnetic powder is less than 40% by volume, the magnetic properties are insufficient.
[0036]
【Example】
EXAMPLES Hereinafter, although this invention is demonstrated in detail based on an Example, it cannot be overemphasized that this invention is not limited only to this Example.
[0037]
Example 1
This example is a hysteresis bond magnet used as a torque limiter, and as a magnetic oxide powder, the coercive force is 500 Oe (39.8 KA / m), the average particle size is 1.2 μm, and the compression density is 3.0 g / cm. ³ magnetoplumbite type strontium ferrite 85 wt%, polyamide 66 14 wt% as binder resin, lead stearate as lubricant and vinyltrichlorosilane as coupling agent from 0.3 wt% and 0.7 wt% respectively The resulting magnet composition was injection molded with a magnetic field compounding injection mold. As shown in FIG. 1, the obtained hysteresis bond magnet 6 has a cylindrical shape (inner diameter: 19 mm, outer diameter: 21 mm, length: 21 mm), and the orientation of the magnetic powder is indicated by a wavy line.
[0038]
Example 2
In this embodiment, in the hysteresis bonded magnet shown in the first embodiment, as shown in FIG. 2, the working surface side (inner side in the figure) 7 is anisotropy, and the non-working surface side (outer side) on the opposite surface side. ) 8 is the same as in Example 1 except that 8 is isotropic. The isotropic opposite surface side 8 plays the role of a back yoke to increase the magnetic field and increase the hysteresis torque.
FIG. 3 shows a state in which a columnar (diameter 18.5 mm, length 21 mm) permanent magnet 9 is mounted in a cylindrical hysteresis bond magnet 6. The orientation of the hysteresis bond magnet 6 and the magnetization of the permanent magnet 9 are illustrated. The pattern is indicated by a wavy line.
[0039]
Example 3
In this embodiment, the hysteresis bonded magnet shown in the first embodiment is made anisotropic on the working surface side (inner side in the figure) 7 of the hysteresis bonded magnet 6 in the thickness direction as shown in FIG. Example 1 is the same as Example 1 except that a ferromagnetic material (iron plate, thickness 0.5 mm) 10 is arranged on the non-working surface side 8 on the side (outside). The effect of increasing the hysteresis torque is obtained by the back yoke effect of the ferromagnetic body 10.
FIG. 5 shows a state in which a cylindrical permanent magnet 9 is mounted in a cylindrical hysteresis bond magnet 6, and the orientation of the hysteresis bond magnet 6 and the magnetization pattern of the permanent magnet 9 are indicated by wavy lines.
[0040]
【The invention's effect】
As described above, the hysteresis bonded magnet of the present invention is inexpensive and rich in safety, and is useful for a hysteresis generator such as a general-purpose torque limiter, damper, shock absorber, clutch, accelerator pedal and the like.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a hysteresis bonded magnet of the present invention.
FIG. 2 is a cross-sectional view showing another example of the hysteresis bonded magnet of the present invention.
FIG. 3 is a schematic view showing a state where a permanent magnet is mounted in the hysteresis bond magnet of FIG. 2;
FIG. 4 is a cross-sectional view showing still another example of the hysteresis bonded magnet of the present invention.
5 is a schematic view showing a state in which a permanent magnet is mounted in the hysteresis bond magnet of FIG. 4. FIG.
FIG. 6 is a schematic sectional view showing a conventional torque limiter.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Hysteresis board 2 Casing 3 Shaft 4 Sintered magnet 5 Clearance 6 Hysteresis bond magnet 7 Working surface side 8 Non-working surface side 9 Permanent magnet 10 Ferromagnetic material

Claims (7)

Oxide magnetic powder 75 to 95 having a coercive force of 100 to 1100 Oe (8.0 to 87.6 KA / m), an average particle size of 0.5 μm or more, and a compression density of 2.7 to 3.5 g / cm ^3. A hysteresis bond magnet comprising: wt% and a binder resin of 25 to 5 wt%. The hysteresis bond magnet according to claim 1, comprising 0.1 to 5% by weight of a lubricant and 0.5 to 3% by weight of a coupling agent with respect to 100% by weight of the total of the oxide magnetic powder and the binder resin. The hysteresis bond magnet according to claim 1 or 2, wherein the oxide magnetic powder is oriented in the thickness direction. The hysteresis bond magnet according to any one of claims 1 to 3, wherein the working surface side is anisotropic in the thickness direction and the non-working surface side is isotropic. The hysteresis bond magnet according to any one of claims 1 to 4, wherein the working surface side is anisotropic in the thickness direction, and a ferromagnetic material is disposed on the non-working surface side. The hysteresis bond magnet according to any one of claims 1 to 5, comprising a cylindrical shape or a disk shape. The hysteresis bond magnet according to any one of claims 1 to 6, which is used for a torque limiter.

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