WO2015041187A1

WO2015041187A1 - Magnetic encoder, and production method therefor

Info

Publication number: WO2015041187A1
Application number: PCT/JP2014/074320
Authority: WO
Inventors: 村上　豪; 矢部　俊一; 内山　貴彦
Original assignee: 日本精工株式会社
Priority date: 2013-09-20
Filing date: 2014-09-12
Publication date: 2015-03-26
Also published as: CN105556249A; JP2015059919A

Abstract

This magnetic encoder is produced by: applying, during insert moulding, an adhesive agent in a hardened state or a cured state so as to not be washed away from a fixed member by a molten substance of a plastic magnet material, said adhesive agent being capable of having a coating state thereof controlled by way of heating; removing from a die, after completion of the insertion moulding, a moulded article for each slinger; and heating said adhesive agent, after completion of injection moulding, to induce adhesion and establish an adhesive bond between a magnet part and the fixed member.

Description

Magnetic encoder and manufacturing method thereof

The present invention relates to a method for manufacturing a magnetic encoder used for detecting the rotational speed of a rotating body, and to a magnetic encoder manufactured by the method.

Conventionally, magnetic encoders used for wheel bearings include rubber magnet encoders that use magnetic rubber mixed with rubber and plastic magnet encoders that consist of plastic magnets mixed with plastic. When comparing the two, the plastic magnet is easy to injection mold (magnetic field molding) in a state where a magnetic field is applied, which makes it possible to achieve higher output than when using a rubber magnet with the same amount of magnetic powder. In addition to being able to obtain magnetic encoders with excellent magnetic properties, plastic magnet encoders have environmental reliability (heat oxidation resistance, water resistance, oil resistance, chemical resistance, etc.) and wear resistance. However, it is known to be superior to rubber magnet encoders.

For the above reasons, the plastic magnet encoder is more suitable than the rubber magnet encoder for the requirements based on the assumption that it is used in a harsh environment assuming a higher output (high magnetic force) and BRICS. In the future, the market for plastic magnet encoders is expected to expand more and more based on the above requirements.

By the way, one of the biggest technical issues in developing a plastic magnet encoder that can be applied to wheel bearings used in extremely harsh environments such as automobile undercarriage is How to establish a highly reliable bond with the fixing member.

Before the vehicle reaches the end of its life, the adhesive force between the plastic magnet and the fixing member should disappear, and the plastic magnet may fall off from the fixing member. 1 and 2, as a manufacturing method for obtaining a plastic magnet encoder that realizes highly reliable adhesion, molding and adhesion are simultaneously performed by an insert molding method using a fixing member coated with an adhesive in advance as a core (molding adhesion). A method has been established to overcome the above problems.

However, according to the manufacturing methods disclosed in Patent Documents 1 and 2, it is possible to obtain a plastic magnet encoder with highly reliable adhesion that can be applied even in harsh environments. After setting a fixed member pre-applied with an adhesive to the mold, inject high-temperature, high-pressure plastic magnet material into the mold controlled to the desired temperature, and hold it as it is for a certain period of time after the injection is completed However, this is a manufacturing method in which an adhesive reaction between a certain amount of the plastic magnet and the adhesive proceeds in the mold. Therefore, in order to advance the adhesion reaction in the mold, the process includes a process of holding the insert molded body in the mold for a certain period of time, so that there is a limit in shortening the tact time.

Japanese Patent No. 4178812 Japanese Patent No. 4189696

As described above, in the manufacturing methods according to Patent Documents 1 and 2, although high-quality products can be obtained, there is room for improvement in terms of production efficiency, that is, production cost reduction. Therefore, in the manufacturing process of the magnetic encoder, the present invention maintains a good adhesion state between the fixing member and the plastic magnet to ensure high reliability, shortens the tact time, increases the production efficiency, and reduces the production cost. It aims to plan.

The present invention solves the above-described problems, and provides the following first and second manufacturing methods and a magnetic encoder.
(1) A method of manufacturing a magnetic encoder for detecting the rotational speed of a rotating body, wherein a plastic magnet material containing a resin and magnetic powder is insert-molded using a fixing member coated with an adhesive in advance as a core. In the manufacturing method of the magnetic encoder for magnetizing the magnet portion in the circumferential direction after integrating the fixing member and the magnet portion made of the plastic magnet material,
The adhesive is an adhesive whose coating state can be controlled by heat treatment, and is applied in a cured state or a solidified state that does not flow away from the fixing member by a melt of the plastic magnet material during insert molding. And
A first manufacturing method characterized in that, after completion of insert molding, the molded product is taken out of the mold together with the slinger.
(2) A method of manufacturing a magnetic encoder for detecting the rotational speed of a rotating body, wherein a plastic magnet material containing a resin and magnetic powder is insert-molded with a fixing member previously coated with an adhesive as a core. In the manufacturing method of the magnetic encoder for magnetizing the magnet portion in the circumferential direction after integrating the fixing member and the magnet portion made of the plastic magnet material,
The adhesive is an adhesive capable of controlling the state of the coating film by heat treatment, and after completion of injection molding, the heat treatment is completed to complete the adhesion, and the adhesive bonding between the magnet portion and the fixing member is performed. 2nd manufacturing method characterized by complete | finishing.
(3) A magnetic encoder manufactured by the manufacturing method according to (1) or (2) above.

The first and second manufacturing methods according to the present invention use an insert molding method using an adhesive capable of controlling the state of the coating film by heat treatment. Since the tact time can be greatly shortened while ensuring the reliability, drastic cost reduction can be realized. Therefore, the magnetic encoder obtained by this method is also highly reliable and inexpensive.

It is sectional drawing which shows an example of a rolling bearing unit provided with a magnetic encoder. It is sectional drawing which shows the sealing device provided with the magnetic encoder. It is a perspective view which shows an example of a magnetic pole formation ring.

Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a cross-sectional view showing a state of being incorporated in a wheel support rolling bearing unit 2a for supporting a non-driven wheel, which is supported by an independent suspension, as an example of a magnetic encoder.

In the illustrated rolling bearing unit 2a, an outer ring 5a that is a fixed ring, a hub 7a and an inner ring 16a that are rotating wheels (rotating bodies) that rotate integrally with a mounting flange 12 for fixing a wheel (not shown),

Balls

17a and 17a, which are a plurality of rolling elements, are arranged between the outer ring 5a and the hub 7a and the inner ring 16 so as to be freely rollable in the circumferential direction, and a magnetic encoder 26 is included.

The inner ring 16a that is externally fitted to the small-diameter step portion 15 formed at the inner end portion of the hub 7a is restrained by a caulking portion 23 that is formed by caulking the inner end portion of the hub 7a radially outward. By attaching, it is fixedly coupled to the hub 7a. Further, the wheel is formed by a stud 8 planted at a predetermined interval in the circumferential direction on a mounting flange 12 formed at a portion protruding from the outer end portion of the outer ring 5a which is a fixed wheel at the outer end portion of the hub 7a. It can be connected and fixed freely. On the other hand, the outer ring 5a can be coupled and fixed to a knuckle or the like (not shown) constituting a suspension device by a coupling flange 11 formed on the outer peripheral surface thereof. Between the outer ring 5a, the hub 7a, and the inner ring 16a, a plurality of

balls

17a and 17a guided by the cage 18 are arranged so as to be rotatable in the circumferential direction.

Furthermore,

seal rings

21a and 21b are provided between the inner peripheral surfaces of both ends of the outer ring 5a, the intermediate outer peripheral surface of the hub 7a, and the inner end peripheral surface of the inner ring 16a, respectively. These seal rings 21a and 21b block the space provided with the

balls

17a and 17a from the outer space between the inner peripheral surface of the outer ring 5a and the outer peripheral surfaces of the hub 7a and the inner ring 16a.

Each of the

seal rings

21a and 21b is formed by bending a mild steel plate and reinforcing the

elastic members

22a and 22b with

cored bars

24a and 24b having an L-shaped cross section and an annular shape as a whole. Each of

such seal rings

21a and 21b has a

metal core

24a and 24b fitted into both ends of the outer ring 5a by an interference fit, and the tip ends of the seal lips formed by the respective

elastic members

22a and 22b are connected to the hub. The slinger 25 is externally fitted and fixed to the outer peripheral surface of the intermediate portion 7a or the outer peripheral surface of the inner end portion of the inner ring 16a.

As shown in FIG. 2, the magnetic encoder 26 includes a slinger 25 that is a fixed member and a magnetic pole forming ring 27 that is a magnet portion integrally joined to the side surface of the slinger 25. As shown in FIG. 3, the magnetic pole forming ring 27 is a multipolar magnet, and N and S poles are alternately formed in the circumferential direction. Then, a magnetic sensor 28 is disposed facing the magnetic pole forming ring 27 (see FIG. 1).

Further, the magnetic pole forming ring 27 of the magnetic encoder 26 is composed of a multipolar plastic magnet made of magnetic powder and a resin composition serving as a binder thereof. Then, as will be described later, the magnetic encoder 26 uses a slinger 25 pre-applied with an adhesive as a core, insert-molds a plastic magnet material, and then performs heat treatment to bond the adhesive and the plastic magnet. After the reaction is progressed and the adhesion between the two is completed, the resultant bonded joined body is produced by multipolar magnetization in the circumferential direction.

Here, there is no restriction | limiting in a plastic magnet, It consists of a resin composition which has magnetic powder and a binder as a main component. As the main component of the binder, polyamide-based resin, specifically, polyamide 6, polyamide 66, polyamide 11, polyamide 12, polyamide 612, or the like can be used. When mounted on a hub bearing for a drive wheel, it is basically exposed to the external environment, and calcium chloride used as a snow melting material may splash with water. By adjusting (increasing) the blending amount, necessary and sufficient durability can be ensured, so that the application of the polyamide-based resin does not pose any problem. However, among the polyamide-based resins, so-called High Nylon polyamide 11, polyamide 12, polyamide 612, and further, polyamide 410, polyamide 6T which is a semi-aromatic polyamide obtained by partially copolymerizing terephthalic acid with an adipic acid unit. / 6-6, Polyamide 6T / 6I, Polyamide 6T / 6I / 6-6, Polyamide 6T / M-5T, Polyamide 9T, etc., their water absorption is relatively small, so that the snow melting resistance is Since it becomes favorable, it is especially preferable.

As the magnetic powder, ferrite such as strontium ferrite or barium ferrite, rare earth magnetic powder such as neodymium-iron-boron, samarium-cobalt, samarium-iron can be used. In addition, when using rare earth-based magnetic powder, the oxidation resistance is low compared to ferrite, so in order to maintain stable magnetic properties over a long period of time, electro nickel plating, electroless nickel plating, A surface treatment layer such as an epoxy resin coating, a silicon resin coating, or a fluororesin coating may be provided on the encoder surface.

As the magnetic powder, ferrite such as strontium ferrite is most suitable in consideration of weather resistance. Further, in order to improve the magnetic properties of the ferrite, lanthanum and cobalt are mixed, or a part of the ferrite is neodymium- It may be replaced with rare earth magnetic powder such as iron-boron, samarium-cobalt, samarium-iron.

The content of magnetic powder in the plastic magnet is preferably 40 to 80% by volume. If the content of magnetic powder is less than 40% by volume, the magnetic properties are inferior and it becomes difficult to carry out multipolar magnetization in the circumferential direction at a fine pitch. On the other hand, if the content exceeds 80% by volume, the amount of resin binder As a result, the strength of the entire magnet is lowered, and at the same time, molding becomes difficult and practicality is lowered.

In addition, various additives can be added to the resin composition depending on the purpose. For example, to make the magnetic encoder more reliable under conditions where repeated thermal shocks of −40 ° C. to 120 ° C. are applied, the polyamide resin, which is the main component of the binder, has high impact strength. It can also be made into the composite material which mix | blended the soft component as a thickness improving agent. The polyamide-based resin that is the main component of the binder is not generally regarded as a brittle material that is inferior in toughness. However, in order to ensure reliability in the severe temperature environment described above, The flexibility (toughness) inherent to the base resin is not always sufficient. In order to ensure further high reliability, it is indispensable to improve flexibility, particularly flexibility at low temperature (or low temperature impact resistance). Therefore, in order to achieve the object of the present invention, low temperature (−40 ° C.) is required. The blending of the soft component as an impact strength improver in (1) is extremely important.

As the soft component, a thermoplastic elastomer containing a soft segment having a glass transition temperature of at least −40 ° C. or less in its molecular structure can be used. Available thermoplastic elastomers include polystyrene-based, polyolefin-based, vinyl chloride-based, polyester-based, polyurethane-based, polyamide-based, polyolefin-based and silicone-based, but more suitable in consideration of encoder performance requirements and usage environment. These are engineering plastic thermoplastic elastomers such as polyester and polyamide, and the soft segment of these thermoplastic elastomers only needs to have a glass transition temperature of −40 ° C. or lower.

The soft segment is not particularly limited as long as it has a glass transition temperature of −40 ° C. or lower and other properties. As candidates for such a soft segment, polyester, polyether, polybutadiene, polyisoprene, polycarbonate, polycaprolactam, and the like are considered, and there are many choices. However, considering the ease of availability from the market, it would be optimal to select a thermoplastic elastomer having polyester or polyether in the soft segment. In particular, in consideration of hydrolysis resistance, the latter containing the polyether segment can be considered more suitable. Specific examples of the polyether segment include polytetramethylene oxide, polypropylene oxide, polyethylene oxide, and copolymers thereof.

Further, a dynamic cross-linking thermoplastic elastomer may be used as the soft component. The dynamically cross-linked thermoplastic elastomer is a polymer alloy composed of a thermoplastic resin and rubber, and has the feature of improving oil resistance and heat resistance, which are disadvantages of conventional thermoplastic elastomers. Since the dynamic cross-linking thermoplastic elastomer can be designed by arbitrarily combining a thermoplastic resin and rubber, various combinations are being studied. In other words, polyolefin-based, styrene-based, polyamide-based, etc. are on the market. For example, Hyperalloy Actimer manufactured by Riken Technos Co., Ltd., which compatibilizes styrene-based dynamically cross-linked elastomer, polyester elastomer, polyurethane elastomer, and polyamide elastomer. In addition, a dynamically crosslinked thermoplastic elastomer made of polyamide resin and silicon rubber marketed by Multibase, Inc. can be used particularly suitably.

The blending amount of the soft component is 5 to 50% by mass, preferably 10 to 35% by mass with respect to the total amount of the resin composition. If it is less than 5% by mass, the absolute amount is too small to give the desired low-temperature flexibility. On the other hand, if it exceeds 50% by mass, the heat resistance is particularly insufficient, and it is not suitable for use as a magnet material for a magnetic encoder.

In addition to the resin composition, a heat stabilizer (heat-resistant processing stabilizer, antioxidant), a light stabilizer, an antistatic material, a plasticizer, an inorganic or organic flame retardant, a reinforcing material, and the like are appropriately used as necessary. It may be added.

In particular, in consideration of the use environment, the addition of a heat stabilizer is preferable, and examples of suitable additions include 2,2,4-trimethyl-1,2-dihydroquinoline polymers as amine-based antioxidants. Such as amine / ketone, diallylamine represented by p, p'-dicumyldiphenylamine, and p-phenylenediamine represented by N, N'-diphenyl-p-phenylenediamine. As antioxidants, monophenols typified by 2,6-di-t-butyl-4-methylphenol and typified by 2,2'-methylenebis (4-methyl-6-t-butylphenol) There is a polyphenol type. On the other hand, a hydroquinone type such as 2,5-di-t-butylhydroquinone can also be used.

Furthermore, a peroxide-decomposing antioxidant (secondary antioxidant) may be used in combination with the amine-based, phenol-based and hydroquinone-based antioxidants in the resin composition. As the secondary antioxidant, a sulfur secondary antioxidant such as 2-mercaptobenzimidazole or a phosphorus secondary antioxidant such as tris (nonylated phenyl) phosphite can be used.

The blending amount of the heat stabilizer is preferably about 0.1 to 3% by mass with respect to the binder resin, but depending on the type, the amount is more than that which does not bloom or adversely affects the physical properties of the resin. May be used.

A magnetic powder-containing resin composition containing the above components is pelletized to obtain a plastic magnet material used for insert molding. At that time, using a biaxial extruder, a kneader, a Banbury mixer, or the like, a binder resin, a soft component, and various additives are kneaded to obtain a resin composition, and the resin composition is extruded and pelletized. The kneading is suitably performed at a temperature of 160 ° C. to 280 ° C. for 1 minute to 20 minutes. Next, using the same kneader, the resin composition pellets and the magnetic powder are kneaded and then extruded to pelletize the magnetic powder-containing resin composition. The kneading at this time is also suitably performed at a temperature of 160 ° C. to 280 ° C. for 1 minute to 20 minutes.

As described above, the manufacturing methods such as Patent Documents 1 and 2 can provide a highly reliable plastic magnet encoder that is excellent in performance and durability and can be applied even under severe vehicle undercarriage environments. After the fixing member (slinger 25) previously coated with an adhesive is set in the mold, injection molding of the plastic magnet material is performed, and after completion of the injection, the mold is held for a certain period of time, and in the mold to some extent Since the adhesion reaction between the plastic magnet and the adhesive proceeds, there is a limit to shortening the tact time.

In response to the above problems, the inventors have conducted extensive research to establish a new manufacturing method for plastic magnet encoders that achieves high reliability equal to or better than that of conventional products and cost reduction far exceeding that of conventional products. As a result, we found a new adhesive that can cancel the process of holding the insert molded body in the mold for a certain period of time in the conventional manufacturing method, and applied it properly, and also controlled the coating state. (In other words, a coating film that realizes a cured or solidified state at a level that does not flow during insert molding, while at the same time heat-treating after molding, the adhesion is rapidly progressed and completed to realize a completely cured or solidified state. The present invention has been completed by clarifying the relationship between the processing conditions of the adhesive and the change in the state of the coating film that enable control of the state). The term “adhesion is completed” means that the magnetic encoder has achieved the adhesion strength and adhesion durability of the magnetic pole forming ring 27 so as to ensure sufficient reliability in an actual use environment.

That is, in the present invention, an adhesive capable of controlling the coating state by heat treatment is used. More specifically, the state of the coating after coating is set to a level that does not flow depending on the heat treatment conditions (temperature, time), even in the desired state, that is, molten plastic magnet material injected at high temperature and high pressure during insert molding. An adhesive (second manufacturing method) that has a state (first manufacturing method) or that completes bonding during the heat treatment after molding and becomes a cured or solidified state is used.

As the adhesive, there is no other limitation as long as the above selection conditions are satisfied, but a thermosetting adhesive and a hot melt adhesive can be preferably used. In addition, as a thermosetting adhesive, an epoxy resin adhesive, a silicone adhesive, and a polyurethane resin adhesive can be used. The thermosetting adhesive also includes a room temperature curable epoxy resin adhesive, a silicone adhesive, and a polyurethane resin adhesive that are cured at room temperature, and these can also be used suitably. Hot melt adhesives include polyurethane hot melt adhesives, polyamide hot melt adhesives, polyester hot melt adhesives, modified olefin hot melt adhesives, silicone hot melt adhesives, and epoxy hot melt adhesives. Agents, phenol resin-based hot melt adhesives, and the like. These may be used after being appropriately modified, for example, modified to impart thermosetting properties.

Since the hot melt adhesive is heated and applied in a molten state and then left at room temperature, the coating surface is solidified to form a coating film, so that it does not flow out of the slinger 25 during insert molding. And by heating again, hardening reaction advances and it hardens | cures completely. However, it is necessary to apply a hot-melt adhesive having a softening point exceeding at least 120 ° C except for a modified product imparted with thermosetting properties. This is because it is considered that the magnetic encoder is exposed to an atmosphere of 120 ° C. For example, when it is exposed to a situation where repeated thermal shocks of −40 ° C. to 120 ° C. are applied, This is because in a hot melt adhesive having a softening point of 120 ° C. or lower, a situation may occur in which the magnetic pole forming ring 27 moves from the slinger 25 and falls off due to the effect of the adhesive softening at a high temperature. .

Furthermore, among the above-mentioned adhesives, it is particularly preferable to apply a solventless type for the thermosetting epoxy resin adhesive, the thermosetting silicone adhesive, and the thermosetting polyurethane resin adhesive. Some adhesives are used in a state where they are dissolved or dispersed in an organic solvent. However, the use of a solvent-free adhesive eliminates the need for treatment of the organic solvent, which is preferable from the environmental viewpoint.

As a method of applying the adhesive to the slinger 25, when the viscosity of the hot melt adhesive or the adhesive is high, the adhesive is extruded from the discharge port of the nozzle and applied directly to the magnet bonding surface of the slinger 25. When using an adhesive solution in which an adhesive is dissolved or dispersed in an organic solvent, the slinger 25 is immersed in the adhesive solution, taken out, and then dried to remove the organic solvent.

The surface of the slinger 25 is preferably roughened by a mechanical treatment such as shot blasting or a chemical etching method in order to make the adhesion with the plastic magnet stronger.

In the first manufacturing method of the present invention, the slinger 25 having the adhesive film formed thereon is used as a core, and a plastic magnet material is injection-molded on the surface to which the adhesive is applied. However, it is in a state of being hardened or solidified to such an extent that it does not flow out of the application surface of the slinger 25 by the injected molten plastic magnet material. In order to obtain such a cured or solidified state, it is preferable to perform a heat treatment according to the type of adhesive. For example, the thermosetting epoxy resin adhesive is heated at 50 to 60 ° C. for about 40 minutes to 1 hour, and the thermosetting silicone adhesive is heated at 100 to 120 ° C. for about 30 minutes to 1 hour to be in a semi-cured state. . Further, it can be cured or solidified by leaving it at room temperature without performing the heat treatment. In addition, as described above, the hot-melt adhesive can be used as it is because the coating film is solidified by leaving it at room temperature after application as described above. Such standing at room temperature eliminates the need for heat treatment equipment and can reduce production costs.

This insert molding only forms a plastic magnet material on a slinger, and the slinger 25 is taken out of the mold immediately after the molding. It is conceivable that the curing of the adhesive partly proceeds due to the heat of the melt of the plastic magnet material during the insert molding, but the adhesive is substantially hardly cured, and the molded product of the plastic magnet material (magnetic pole formation) The ring 27) is temporarily held so as not to fall off the slinger 25.

Next, as in the second manufacturing method, the slinger 25 and the magnetic pole forming ring 27 are firmly bonded to each other by heating to a temperature higher than the temperature for accelerating the reaction of the adhesive to advance and complete the bonding. . As a heating method, it is preferable to use a heating furnace because a large amount of precursor can be treated at once.

In insert molding, it is preferable to use a disk gate type injection molding machine. The molten magnetic material spreads in a disk shape, and then flows into the mold corresponding to the inner diameter thick portion, so that the flake-like magnetic powder contained therein is oriented parallel to the surface. In particular, the portion between the inner diameter portion and the outer diameter portion detected by the rotation sensor in the vicinity of the inner diameter thick portion has higher orientation and is very close to the axial anisotropy oriented in the thickness direction. In addition, when a magnetic field is applied to the mold in the thickness direction during molding (magnetic field molding), the anisotropy becomes closer to perfection. On the other hand, when the side gate is used even if magnetic field shaping is performed, the orientation of the weld part is completely anisotropic in the process of gradually increasing the viscosity of the molten magnetic material toward solidification. It is difficult to cause a crack or the like to occur in the welded portion where the magnetic field characteristics are lowered and the mechanical strength is lowered due to long-term use.

In magnetic field molding, after a mold is filled with a plastic magnet material, demagnetization is performed with a magnetic field opposite to the magnetization direction during cooling in the mold. Next, after removing the gate portion, the adhesive is completely cured, and further demagnetized to a magnetic flux density of 2 mT or less, more preferably 1 mT or less, using an oil capacitor type demagnetizer.

Next, gate cutting is performed, and heating is performed at a constant temperature for a certain time in a thermostatic bath or the like in order to completely cure the adhesive. In some cases, heating can be performed at a high temperature for a short time, such as high-frequency heating.

As described above, according to the manufacturing method of the present invention, after the plastic magnet material is insert-molded into the slinger 25 to which the adhesive is applied, the holding for advancing the bonding becomes unnecessary, and the tact time is greatly shortened. . Further, the treatment for completing the adhesion can also be performed in a heating furnace capable of performing a large amount of treatment. Therefore, the production efficiency is improved and the production cost is reduced.

Then, after heating to complete the adhesion, the magnetic pole forming ring 27 is multipolar magnetized using a yoke coil to obtain a magnetic encoder. The number of poles is about 70 to 130, preferably 90 to 120. If the number of poles is less than 70, the number of poles is too small and it is difficult to accurately detect the rotational speed. On the other hand, when the number of poles exceeds 130, each pitch becomes too small, and it is difficult to suppress a single pitch error, and practicality is low.

Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited thereto.

[Examples 1 to 5, Comparative Example 1]
(Preparation of test specimen)
First, in a biaxial extruder, polyamide 12, soft component (polyamide-based thermoplastic elastomer) is 30% by mass of the total amount of the resin composition, and heat stabilizer (N, N′-diphenyl-p-phenylenediamine) is added to 0.1%. The resin composition was obtained by adding and kneading the mixture so as to be 5% by mass. The kneading was performed at 250 ° C. for 5 minutes. Thereafter, the resin composition was pelletized by a usual method.

Next, ferrite magnetic powder was put into the resin composition pellets, kneaded at 250 ° C. for 10 minutes using a biaxial extruder, and then extruded. The magnetic powder was 60% by volume of the plastic magnet material. The extruded magnetic powder-containing resin composition was pelletized.

Also, a stainless steel slinger (see FIG. 2) having an L-shaped cross section was prepared, and the adhesive surface was roughened by shot blasting.

Then, the adhesive shown in Table 1 was applied to the adhesive surface of the slinger and cured by heating at the indicated temperature and time.

Next, a slinger coated with an adhesive was set on the mold of an injection molding machine, and insert molding was performed using the pellets of the above-described magnetic powder-containing resin composition. Then, after the insert molding was completed, the slinger was taken out of the mold and stored in a heating furnace, and heat treatment was performed at 150 ° C. for 1 hour to complete the bonding. Subsequently, after taking out from the heating furnace and cooling, the magnetic encoder test body was produced by magnetizing in multiple poles using a yoke coil.

(Thermal shock resistance test)
A thermal shock test was repeatedly performed on the magnetic encoder specimens of the example and the comparative example. The test conditions were 1000 cycles, with one cycle consisting of holding (120 ° C. for 30 minutes) and holding (−40 ° C. for 30 minutes). And after 1000 cycles, while visually evaluating the external appearance, the damage state after a peeling test (forced peeling test of a plastic magnet part) was evaluated. The results are also shown in Table 1. In the appearance evaluation, “◯” is marked in the table as good when there is no change in cracks, chips, cracks and product shape, and “ × ”was marked. Also, in the peeling test, when the magnet part is damaged, it is judged that the adhesive strength is good, and “◯” is marked in the table, and when it is not broken, it is judged as poor adhesion, and “X” is marked in the table. did.

As shown in Table 1, in each example according to the present invention, the appearance is good, and a strong adhesive strength is obtained even in a peeling test. On the other hand, in Comparative Example 1, although a hot melt adhesive was used, the linear expansion of the slinger and the plastic magnet when the melting point was lower than 120 ° C. and repeated thermal shocks of −40 ° C. to 120 ° C. were applied. Stress is applied to the bonded part based on the difference in the coefficient. However, when the melting point is lower than 120 ° C. as described above, the bonded part is softened and deformed by the stress generated in the bonded part at high temperature (120 ° C.). As a result, the plastic magnet moved from the slinger (with a shape change), and further, due to the influence, the peel strength was insufficient in the peeling test.

Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on September 20, 2013 (Japanese Patent Application No. 2013-195854), the contents of which are incorporated herein by reference.

According to the present invention, the magnetic encoder used for the wheel bearing can be efficiently manufactured with a shortened tact time, and the production cost of the magnetic encoder can be reduced.

2a Hub unit bearing (bearing)
5a Outer ring (fixed ring)
7a Hub (rotating wheel)
11 Connecting flange 12 Mounting flange 16a Inner ring (rotating ring)
17a ball (rolling element)
21a,

21b Seal rings

22a, 22b

Elastic members

24a, 24b Core metal 25 Slinger (fixing member)
26 Magnetic encoder 27 Magnetic pole forming ring (magnet part)
28 sensors

Claims

A method of manufacturing a magnetic encoder for detecting the rotational speed of a rotating body, wherein a fixing member pre-applied with an adhesive is used as a core, and a plastic magnet material containing resin and magnetic powder is insert-molded and fixed. In a method of manufacturing a magnetic encoder that integrates a member and a magnet portion made of the plastic magnet material, and then magnetizes the magnet portion in a circumferential direction,
The adhesive is an adhesive whose coating state can be controlled by heat treatment, and is applied in a cured state or a solidified state that does not flow away from the fixing member by a melt of the plastic magnet material during insert molding. And
A method of manufacturing a magnetic encoder, comprising: removing a molded product together with a slinger from a mold after completion of insert molding.
A method of manufacturing a magnetic encoder for detecting the rotational speed of a rotating body, wherein a fixing member pre-applied with an adhesive is used as a core, and a plastic magnet material containing resin and magnetic powder is insert-molded and fixed. In a method of manufacturing a magnetic encoder that integrates a member and a magnet portion made of the plastic magnet material, and then magnetizes the magnet portion in a circumferential direction,
The adhesive is an adhesive capable of controlling the state of the coating film by heat treatment, and after completion of injection molding, the heat treatment is completed to complete the adhesion, and the adhesive bonding between the magnet portion and the fixing member is performed. A method of manufacturing a magnetic encoder, comprising: completing the method.
A magnetic encoder manufactured by the manufacturing method according to claim 1 or 2.