JP2009097994A - Magnetic encoder and manufacturing method thereof, and rolling bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the productivity of a magnetic encoder by easily orientating magnetic powder and reducing mold contamination when performing heating compression molding to unvulcanized magnetic rubber while applying a magnetic field. <P>SOLUTION: The magnetic encoder 16 includes a multipolar magnet 23 made of rubber where magnetic poles are arranged circumferentially and alternately. The multipolar magnet 23 is formed by performing heating compression molding to unvulcanized magnetic rubber containing a rubber composition, magnetic powder, an inner die lubricant, and a curing agent while applying a magnetic field in a prescribed direction. The rubber composition contains solid rubber and liquid rubber. The content of the liquid rubber is not less than 10 pts.wt and not more than 100 pts.wt to 100 pts.wt solid rubber. The content of the inner die lubricant is not less than 0.5 pts.wt and not more than 2.5 pts.wt to 100 pts.wt solid rubber. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a magnetic encoder, a method for manufacturing a magnetic encoder, and a rolling bearing, and more particularly, to a magnetic encoder including a rubber multipole magnet, a method for manufacturing the same, and a rolling bearing including such a magnetic encoder.

2. Description of the Related Art Conventionally, as a bearing used in an automobile ABS (Antilock Break System) apparatus, there is a rolling bearing with a seal including a magnetic encoder. Such a rolling bearing is disclosed in, for example, JP-A-6-281018 (Patent Document 1). According to Patent Document 1, a rotation detection device that detects a rotation speed and a rotation direction includes a magnetic encoder and a sensor. The magnetic encoder includes a rubber multi-pole magnet having magnetic poles alternately formed in the circumferential direction and a slinger that supports the magnet. The sensor detects alternating magnetic poles of a magnetic encoder that rotates with the rotating shaft. In this way, the rotation detection device detects the number of rotations and the like.
JP-A-6-281018

  In the magnetic encoder used for the above applications, if the magnetic flux density of the multipolar magnet included in the magnetic encoder is high, the tolerance of the gap (interval) with the sensor for detecting magnetism can be increased. As a result, a large dimensional tolerance in assembling the peripheral members of the magnetic encoder can be obtained, and the manufacturing cost can be reduced. In order to obtain a magnetic encoder having a high magnetic flux density, it is necessary to increase the degree of orientation of the magnetic powder contained in the multipolar magnet. Therefore, it is preferable to form the multipolar magnet by heat compression molding that facilitates orientation of the magnetic powder in the direction in which the magnetic field is applied.

  In order to increase the magnetic flux density of the magnetic powder, it is necessary to increase the content of the magnetic powder with respect to the rubber component. Here, since the magnetic powder is filled while kneading rubber with a kneader or a roll, the rubber used as the binder needs to have a low viscosity. Moreover, it is preferable that rubber | gum is low viscosity also in order to raise the orientation degree by a magnetic field. However, if the viscosity of the rubber is too low, it will easily stick to the mold during heat compression molding, which will contaminate the mold. When such workability deterioration or mold contamination occurs, the productivity of the magnetic encoder is deteriorated.

  An object of the present invention is to provide a magnetic encoder with good productivity.

  Another object of the present invention is to provide a method for manufacturing a magnetic encoder with good productivity.

  Still another object of the present invention is to provide a rolling bearing with good productivity.

  The magnetic encoder according to the present invention includes a rubber multipole magnet in which magnetic poles are alternately arranged in the circumferential direction. The multipolar magnet is formed by heat compression molding an unvulcanized magnetic rubber containing a rubber composition, magnetic powder, an internal release agent and a vulcanizing agent while applying a magnetic field in a predetermined direction. The rubber composition includes solid rubber and liquid rubber. The content of the liquid rubber is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the solid rubber. The content of the internal mold release agent is 0.5 parts by weight or more and 2.5 parts by weight or less with respect to 100 parts by weight of the solid rubber.

  By comprising in this way, when unvulcanized magnetic rubber is heat compression-molded while applying a magnetic field, the magnetic powder is easily oriented, and mold contamination can be reduced. Therefore, the productivity of the magnetic encoder can be improved.

  Preferably, the rubber composition includes NBR. Moreover, it is preferable that NBR contains medium-high nitrile.

  More preferably, the vulcanizing agent includes at least one of a peroxycide vulcanizing agent and a sulfur vulcanizing agent.

  More preferably, the unvulcanized magnetic rubber contains a co-crosslinking agent, and the co-crosslinking agent contains a bismaleimide-based co-crosslinking agent.

  More preferably, the magnetic rubber contains 1350 parts by weight or more of magnetic powder with respect to 100 parts by weight of the solid rubber.

  More preferably, the magnetic powder includes a ferrite magnetic powder for magnetic field orientation.

  In another aspect of the present invention, a method for manufacturing a magnetic encoder is a method for manufacturing a magnetic encoder including a rubber multi-pole magnet in which magnetic poles are alternately arranged in a circumferential direction, and includes solid rubber and solid rubber 100 weight. 1350 parts by weight or more of the magnetic powder, 100 parts by weight of the solid rubber, 10 parts by weight to 100 parts by weight of the liquid rubber, and 100 parts by weight of the solid rubber 0.5 parts by weight to 2.5 parts by weight An unvulcanized magnetic rubber containing an internal mold release agent and a vulcanizing agent in an amount equal to or less than parts by weight is accommodated in an accommodating portion, and an unvulcanized magnetic rubber is applied while applying a magnetic field in a predetermined direction to the accommodating portion. And applying a force to heat compression molding.

  According to such a method for manufacturing a magnetic encoder, when unvulcanized magnetic rubber is subjected to heat compression molding while applying a magnetic field, the magnetic powder is easily oriented, and mold contamination can be reduced. Therefore, the productivity of the magnetic encoder can be improved.

  In still another aspect of the present invention, the rolling bearing includes any of the magnetic encoders described above. Such a rolling bearing has good productivity.

  According to such a magnetic encoder and a method for manufacturing the magnetic encoder, the magnetic powder can be easily oriented and the mold contamination can be reduced when the unvulcanized magnetic rubber is subjected to heat compression molding while applying a magnetic field. . Therefore, the productivity of the magnetic encoder can be improved.

  Also, such a rolling bearing has good productivity.

  Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view showing a part of a rolling bearing including a magnetic encoder according to an embodiment of the present invention. With reference to FIG. 1, the rolling bearing 11 supports a rotating shaft (not shown). Such a rolling bearing 11 is used as a bearing for supporting the axle of an automobile.

  The rolling bearing 11 includes a ball 12 as a rolling element, an inner ring 13 disposed on the inner diameter side of the ball 12, an outer ring 14 disposed on the outer diameter side of the ball 12, and a cage (not shown). 2), a magnetic encoder 16 for detecting the rotational speed of the rotary shaft, and a seal 17 for sealing the inside of the bearing. The inner ring 13 is fixed to the rotating shaft and rotates together with the rotating shaft. On the other hand, the outer ring 14 is fixed to a housing (not shown). The ball 12 rolls on the raceway surfaces 15a and 15b provided on the inner ring 13 and the outer ring 14 when the rotary shaft rotates.

  The seal 17 includes a cored bar 31 having rigidity and a rubber part 32 having elasticity. The cored bar 31 is attached and fixed to the outer ring 14. The rubber part 32 is configured to cover a part of the cored bar 31. The rubber portion 32 is in contact with a slinger 24 described later at a plurality of locations with appropriate pressure. Specifically, a plurality of lip portions protruding to the inner diameter side of the seal 17 or the bearing outer side are in contact with the slinger 24. In this way, the inside of the rolling bearing 11 is sealed. By doing so, it is possible to prevent leakage of the lubricating oil sealed in the interior and prevent foreign matter from entering the rolling bearing 11.

  A rotation detection device 21 that detects the number of rotations of the rotation shaft and the like includes a magnetic encoder 16 included in the rolling bearing 11 and a rotation sensor 22. The magnetic encoder 16 and the rotation sensor 22 are provided at positions facing each other. The rotation sensor 22 is fixed to the housing together with the outer ring 14 and the like, for example.

  Here, the configuration of the magnetic encoder 16 will be described. The magnetic encoder 16 includes a rubber multipole magnet 23 in which magnetic poles are alternately arranged in the circumferential direction, and a metal slinger 24 that holds the multipole magnet 23. The slinger 24 includes a cylindrical portion 28a and a flange 28b extending from the one end of the cylindrical portion 28a to the outer diameter side. The multipolar magnet 23 is held on the outer side of the flange 28b.

  FIG. 2 is a conceptual diagram showing the configuration of the multipolar magnet 23. Referring to FIGS. 1 and 2, multipolar magnet 23 is annular and has a through hole at the center thereof. The multipolar magnet 23 is magnetized in a multipolar manner in the circumferential direction, and is configured such that N poles 27 a and S poles 27 b are alternately arranged on a PCD (Pitch Circle Diameter) 26.

  The multipolar magnet 23 held by the slinger 24 rotates with the inner ring 13 as the rotation shaft rotates. At this time, the change in the magnetic force of the N pole 27 a and the S pole 27 b of the multipolar magnet 23 is read by the detection unit 25 of the rotation sensor 22 disposed on the outer side in the axial direction and facing the multipolar magnet 23. In this way, the rotation detection device 21 detects the number of rotations of the rotation shaft and the like.

  Next, the configuration of the manufacturing apparatus for the magnetic encoder 16 will be described. FIG. 3 is a schematic sectional view of a manufacturing apparatus for the magnetic encoder 16. In FIG. 3 and the like, the upper side of the drawing is the upward direction. With reference to FIG. 3, the magnetic encoder manufacturing apparatus 51 can perform heat compression molding while applying a magnetic field. The magnetic encoder manufacturing apparatus 51 includes a press 52 as pressurizing means for applying pressure, a movable shaft 55a attached to the movable plate 54a, a support column 53 supporting the movable plate 54a, and a fixed shaft attached to the fixed plate 54b. 55b. A press 52 is attached above the movable plate 54a. With the press 52, the movable plate 54a and the movable shaft 55a can move downward and load a load.

  The magnetic encoder manufacturing apparatus 51 is attached to the distal ends of the movable shaft 55a and the fixed shaft 55b, and a mold core 71 as a housing portion that houses unvulcanized magnetic rubber that is a material of a multipolar magnet described later. A mold part 60 disposed around the mold core 71, a heater 58 disposed around the mold part 60 as a heating means for heating the mold part 60 and the mold core 71, A heat insulating plate 59 arranged in the vertical direction of the mold part 60 to block heat transfer from the mold part 60, a cooling jacket pipe 57 arranged in the vertical direction of the heat insulating plate 59, and the cooling jacket pipe 57 above and below And a coil 56 as magnetic field generation means for generating a magnetic field in a predetermined direction.

  The cooling jacket tube 57 as a cooling means cools the coil 56 with the refrigerant from the cooler 62 sent through the pipe 61. The heat insulating plate 59 reduces heat transfer from the mold part 60 to the coil 56. In addition, the support | pillar 53, the movable plate 54a, the fixed plate 54b, the movable shaft 55a, and the fixed shaft 55b are comprised with the magnetic material, and the cooling jacket pipe | tube 57 and the metal mold | die part 60 are comprised with the nonmagnetic material. In FIG. 3, the hatched portion is a member made of a magnetic material.

  FIG. 4 is a cross-sectional view of the mold core 71. FIG. 5 is a perspective view of the mold core 71. FIG. 6 is a perspective view of the lower mold core 72 b included in the mold core 71. Referring to FIGS. 3 to 6, a mold core 71 is composed of an upper mold core 72a and a lower mold core 72b, each having a disk shape. A recess 75a that is recessed in the thickness direction is provided at the center of the upper mold core 72a. A convex portion 75b that swells in the thickness direction is provided at the center of the lower mold core 72b. The mold core 71 is disposed so as to fit the concave portion 75a provided in the upper mold core 72a and the convex portion 75b provided in the lower mold core 72b. The outer shape of the multipolar magnet 23 is formed by the upper mold core 72a and the lower mold core 72b.

  The upper mold core 72a and the lower mold core 72b are composed of a magnetic material 74 and a nonmagnetic material 73, respectively. The nonmagnetic material 73 is disposed on the radial center side and the outer diameter side of the upper mold core 72a and the lower mold core 72b, and the magnetic material 74 is sandwiched between the nonmagnetic materials 73 in the radial direction. Placed in the part. When the upper mold core 72a and the lower mold core 72b are fitted together, the magnetic materials 74 and the nonmagnetic materials 73 are positioned in the vertical direction, respectively. The position where the magnetic materials 74 provided in the upper mold core 72a and the lower mold core 72b are closest to each other is preferably close to the center in the radial direction in the region where the magnetic material 74 is located. By doing so, the magnetic flux density can be increased at this position when the magnetic rubber is vulcanized.

  In the lower mold core 72b, a portion made of the magnetic material 74 is recessed in the thickness direction, and the slinger 64 can be attached. When the lower mold core 72b to which the slinger 64 is attached is fitted to the upper mold core 72a, the magnetic material 74 is disposed in the vertical direction of the slinger 64. In this case, the slinger 64 is attached with the surface 65 holding the multipolar magnet as the upper side.

  Note that, from the viewpoint of easy understanding, the magnetic encoder manufacturing apparatus 51 shown in FIG. 3 is configured to include one mold core 71, but by attaching a plurality of mold cores 71, the magnetic encoder can be It can be molded at the same time. That is, it is possible to form a plurality of magnetic encoders by one molding so that a plurality of mold cores 71 are arranged so as to be arranged in parallel in the left-right direction.

  By energizing the coil 56, a magnetic field can be generated in the magnetic encoder manufacturing apparatus 51. Here, as described above, since the members constituting the magnetic encoder manufacturing apparatus 51 are made of a magnetic material or a non-magnetic material, in the magnetic encoder manufacturing apparatus 51, an arrow III indicated by a one-dot chain line in FIG. Magnetic field loops can be formed in the direction. In this way, heat compression molding is performed with the magnetic field at a predetermined position in the mold core 71, specifically, a portion made of the magnetic material 74 being dense. By doing so, the magnetic powder contained in the magnetic rubber can be highly oriented during the heat compression molding. In such heat compression molding, the magnetic powder can be oriented along the magnetic field in each part of the magnetic rubber during the flow of the material, that is, the unvulcanized magnetic rubber. Here, according to injection molding using a magnetic field, for example, the magnetic powder is oriented in a direction different from the direction of the magnetic field on the end portion side where the material flows. However, such fear can be reduced by heat compression molding.

  Next, a method for manufacturing the magnetic encoder 16 will be described. First, after the mold core 71 is heated to the vulcanization temperature by the heater 58, the slinger 64 is disposed in the mold core 71. Here, a vulcanizing adhesive is applied in advance to the surface 65 of the slinger 64 where the magnetic rubber is located. Next, the unvulcanized magnetic rubber 63 prepared in advance is set on the upper side of the slinger 64 in the lower mold core 72b, that is, on the surface 65 side where the vulcanized adhesive is applied. As shown in FIG. 7, the unvulcanized magnetic rubber 63 is temporarily formed into a ring shape temporarily.

  Thereafter, the movable plate 54a is moved downward and pressurized, and the magnetic rubber 63 is heated and compressed. Here, the coil 56 is energized to generate a magnetic field, and molding is performed while the magnetic field is applied. After a predetermined time elapses, energization of the coil 56 is stopped. Thereafter, the movable plate 54 a is moved upward, and the magnetic encoder is removed from the mold core 71. In this case, the magnetic rubber 63 is adhered and held on the surface 65 of the slinger 64 by a vulcanizing adhesive. Thereafter, the vulcanized magnetic rubber 63 is magnetized into multiple poles by a magnetizing yoke to form a multiple pole magnet to obtain a desired magnetic encoder.

  Next, the magnetic rubber constituting the multipolar magnet included in the magnetic encoder will be described. As described above, the multipolar magnet is formed by heat-compressing unvulcanized magnetic rubber and magnetizing the vulcanized magnetic rubber to multipolar. Unvulcanized magnetic rubber contains a rubber composition, magnetic powder, softener (process oil), zinc white, anti-aging agent, internal mold release agent, vulcanizing agent and co-crosslinking agent. By including the internal mold release agent, it is possible to improve die wear and the like. The rubber composition includes a solid rubber and a liquid rubber.

  Here, as the rubber composition, natural rubber, polyisobutylene, polyisoprene, isoprene-isobutylene rubber (butyl rubber), styrene-butadiene rubber, styrene-isobutylene-styrene rubber (SBS), styrene-isoprene-styrene rubber (SIS) , Styrene-ethylene-butylene-styrene rubber (SEBS), ethylene-propylene terpolymer (EPDM), acrylonitrile-butadiene rubber (NBR), hydrogenated NBR (H-NBR), fluoro rubber, silicone rubber, acrylic rubber, chloroprene rubber Chlorosulfonated polyethylene, epichlorohydrin rubber, urethane rubber, polysulfide rubber and the like.

  Here, the content of the liquid rubber is preferably 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the solid rubber. When the content of the liquid rubber is less than 10 parts by weight, the amount of heat generated during the kneading process of the magnetic rubber containing the magnetic powder increases and the rubber component deteriorates. There is also a problem of increased torque of the processing machine. Furthermore, the magnetic powder is less likely to be oriented during heat compression molding. On the other hand, if the content of the liquid rubber is more than 100 parts by weight, it may stick to the mold and contaminate the mold.

  Note that NBR, H-NBR, and acrylic rubber are preferable as the above-described magnetic encoder for automobiles. NBR is very high nitrile rubber (nitrile group content 43 wt% or more), high nitrile rubber (nitrile group content 36-42 wt%), medium-high nitrile rubber (nitrile group content) depending on nitrile group content 31 to 35 wt%), medium nitrile rubber (nitrile group content 25 to 30 wt%), and low nitrile rubber (nitrile group content 24 wt% or less). When used in the above applications, the nitrile group content is preferably 31% by weight or more from the viewpoint of improving oil resistance. Furthermore, considering the cost and the like, it is preferable to use a medium-high nitrile rubber. Examples of commercially available NBR include Nipol 1042 (medium-high nitrile), Nipol 1041 (high nitrile), Nipol 1043 (medium nitrile), Nipol 1312 (liquid NBR) (all manufactured by Nippon Zeon Co., Ltd.), and the like.

  As the vulcanizing agent for vulcanizing the unvulcanized magnetic rubber, it is preferable to use a peroxide vulcanizing agent. By doing so, the unvulcanized magnetic rubber can be vulcanized by low-temperature vulcanization. If it does so, a magnetic encoder can be manufactured, suppressing a temperature rise at the time of heat compression molding. Therefore, continuous molding considering mass productivity can be performed, and the productivity of the magnetic encoder can be improved.

  Moreover, sulfur can also be used as a vulcanizing agent. Examples of commercially available sulfur include sulfur (manufactured by Tsurumi Chemical Co., Ltd.). Further, a vulcanization accelerator may be used. Examples of the vulcanization accelerator include a titanium-based vulcanization accelerator. As a commercial item of a Tiraum vulcanization accelerator, Noxeller TT, Noxeller CZ (both manufactured by Ouchi Shinsei Chemical Co., Ltd.) and the like can be mentioned.

  As the peroxide vulcanizing agent when NBR is used as the rubber composition, ketone peroxide, peroxyketal, hydroperoxide, dialkyl peroxide, peroxyester, peroxydicarbonate, A diacyl peroxide vulcanizing agent may be mentioned. In particular, the peroxyketal system is preferable for the low-temperature vulcanization as described above. Moreover, it is preferable to contain 10 weight part or more of the mixture with respect to 100 weight part of solid rubber. Examples of commercially available peroxyketal crosslinking agents include perhexa C40 (1,1 di (t-butylperoxy) cyclohexane, manufactured by Nippon Oil & Fats Co., Ltd.). Moreover, as a commercial item of a diacyl peroxide type | system | group crosslinking agent, Perkadox CH-50L (Dibenzoyl peroxide, Kayaku Akzo Co., Ltd. product) etc. are mentioned.

  A co-crosslinking agent may be used in combination with the vulcanizing agent. By doing so, the magnetic rubber can be vulcanized more efficiently. Examples of the co-crosslinking agent include amine polysulfide series, bismaleimide series, thiraum series, higher methacrylic acid esters, metal salts of methacrylic acid, and triazine thiol series. In particular, a bismaleimide co-crosslinking agent is preferred for use in the low-temperature vulcanization as described above. Moreover, it is preferable to contain 10 weight part or more of the mixture with respect to 100 weight part of solid rubber. Examples of commercially available bismaleimide co-crosslinking agents include Barnock PM (N, N′-m-phenylene bismaleimide, manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.).

  In addition, as a commercially available softener (process oil), SYNTAC HA-35 (manufactured by Kobe Oil Chemical Co., Ltd.) and the like, as a commercial product of zinc white, zinc oxide (manufactured by Sakai Chemical Industry Co., Ltd.), etc. In addition, as a commercial product of an anti-aging agent, as a commercial product of NOCRACK CD (4,4′-bis (α, α-dimethylbenzyl) diphenylamine, manufactured by Ouchi Shinsei Chemical Co., Ltd.), an internal mold release agent, EG-ROLL (manufactured by Sekiko Chemical Co., Ltd.) and the like. In addition, you may use a stearic acid etc. as an internal mold release agent.

  The content of the internal release agent is preferably 0.5 parts by weight or more and 2.5 parts by weight or less with respect to 100 parts by weight of the solid rubber. If the amount is less than 0.5 parts by weight, the releasing effect is small, and magnetic rubber may stick to the mold and the mold may be contaminated. On the other hand, if the amount is more than 2.5 parts by weight, the adhesion between the slinger and the vulcanized magnetic rubber may be lowered.

  In addition, as described above, magnetic rubber is held by adhering to slinger with a vulcanizing adhesive during heat compression molding, and as a vulcanizing adhesive, a phenolic resin-based adhesive having a phenolic resin as an adhesive component is used. preferable. Examples of the phenol resin-based adhesive include adhesives containing novolac type phenol resins, resol type phenol resins, and mixtures of these phenol resins as adhesive components. The novolac type phenol resin can be obtained by reacting phenols with formaldehyde in the presence of an acidic catalyst (hydrochloric acid, oxalic acid, etc.). As phenols in this case, phenol, m-cresol, a mixture of m-cresol and p-cresol, bisphenol A and the like are used. The resol type phenol resin is obtained by reacting bisphenol A and formaldehyde in the presence of a basic catalyst (alkali metal, magnesium hydroxide, etc.).

  Commercially available phenolic resin adhesives include Sixson 715 (manufactured by Rohm and Haas), Metalloc N10, Metalloc N15, Metalloc N15D, Metalloc N31, Metalloc NT, Metalloc PA (all manufactured by Toyo Chemical Laboratories), Chemloc TS1677 -13 (manufactured by Rod Far East) and the like. Moreover, as an adhesive containing a phenol resin and an epoxy resin, METALOC XPH-27 (manufactured by Toyo Chemical Laboratory) and the like can be mentioned. Furthermore, examples of the adhesive containing a phenol resin and a synthetic rubber include METALLOCK C12, METALLOCK N20, METALLOCK N20D, METALLOCK N23, METALOC P (all manufactured by Toyo Chemical Laboratories) and the like.

  As the magnetic powder, hard ferrite and soft ferrite such as barium ferrite and strontium ferrite can be used. These ferrite powders may be granular powders or anisotropic ferrite powders. Further, in the above-described heat compression molding, anisotropic ferrite for magnetic field orientation having a particle shape with a smaller particle resistance during flow in the mold may be used. The magnetic powder may be a rare earth magnetic material. For example, any single magnetic powder of samarium iron (SmFeN) magnetic powder, neodymium iron (NdFeB) magnetic powder, or samarium-cobalt may be used. Further, a mixture of two or more of such rare earth magnetic powders may be used. Further, when the magnetic force is insufficient with only the above-described ferrite powder, rare earth magnetic powder such as samarium iron-based magnetic powder or neodymium iron-based magnetic powder may be mixed with the ferrite powder. By doing so, it can be manufactured at low cost while improving the magnetic force. Examples of commercially available ferrite products include FA600 (manufactured by Toda Kogyo Co., Ltd.).

  In addition, it is preferable that content of magnetic powder shall be 1350 weight part or more with respect to 100 weight part of solid rubber. By doing so, a higher magnetic flux density can be obtained. On the other hand, when the content ratio is high, the amount of the rubber component as the binder is relatively lowered, and the moldability is deteriorated. Therefore, the content of the magnetic powder is preferably less than 1800 parts by weight.

  The strength of the magnetic field applied during heat compression molding is preferably 80000 A / m or more and 800000 A / m or less. This is because if it is less than 80000 A / m, the magnetic flux density of the obtained magnetic encoder may be lowered. Further, the magnetic field is saturated at about 800,000 A / m, and if the magnetic field is larger than 800,000 A / m, heat generation of the coil increases.

Here, scorch time t ₁₀ in a vulcanization time of magnetic rubber described above is not less than 0.5 minutes, the proper vulcanization time t ₉₀ in the vulcanization time is preferably 20 minutes or less. According to such a magnetic rubber, an unvulcanized magnetic rubber can be vulcanized within an appropriate vulcanization time.

  FIG. 8 is a graph showing a vulcanization curve of magnetic rubber. In FIG. 8, the vertical axis represents torque (load), and the horizontal axis represents vulcanization time. Such a vulcanization curve can be obtained with a curast meter V type (Nippon Shoji Co., Ltd.).

Here, a description for the definition of ₁₀ such scorch time t. First, a vulcanization curve at a predetermined vulcanization temperature as shown in FIG. 8 is obtained. Then, in the vulcanization curve, the minimum torque is M _L , the maximum torque is _MH, and straight lines L ₁ and L ₂ that pass through the _ML and _MH and are parallel to the time axis are drawn. When the distance between the two straight lines _L 1, _{L 2} and _{M E,} the M _{E =} M H -M _{L. Here,} as the _M L + 10% M _E, draw a straight line _{L 3} parallel to the time axis. Time at the intersection of the straight line L ₃ and the vulcanization curve becomes the scorch time t _10. Also, _here, through _M L + 90% M _E, draw a straight line _{L 4} parallel to the time axis. Time at the intersection of the straight line L ₄ and vulcanization curve becomes a pressurized硫適positive time t _90.

A magnetic encoder manufacturing apparatus 51 described above, when produced in heat compression molding the magnetic encoder, the scorch time t ₁₀ is shorter than 0.5 minutes, is vulcanized while the mold is set to magnetic rubber There is a risk that it will begin and the original attachment will not be possible. That is, it cannot be appropriately formed by heat compression molding. In particular, this tendency becomes prominent when a plurality of molds are simultaneously molded and a large number are manufactured at a time. On the other hand, when the proper vulcanization time t ₉₀ is longer than 20 minutes, not only the cycle time becomes longer, the time to apply a magnetic field is increased, the temperature rise of the coil by the Joule heat generation and heat transfer due to energization of the coil May cause. Accordingly, the scorch time t ₁₀ at the vulcanization temperature of the magnetic rubber, and 0.5 minutes or more, the proper vulcanization time t ₉₀ at vulcanization temperatures, by 20 minutes or less, by performing continuous molding efficiently Can do.

  Here, the composition and evaluation of the magnetic encoder are shown in Table 1, Table 2, Table 3, Table 4, Table 5, and Table 6. The magnetic field forming conditions are shown below.

  Regarding the magnetic field molding conditions, magnetic rubber was set in a mold heated to 150 ° C., the mold was closed, and the magnetic rubber was applied for 20 minutes immediately after heating and compression to apply a magnetic field. After stopping the application of the magnetic field, it was held in the mold for another 10 minutes. The heat compression molding was performed for a total of 30 minutes. Especially when it is not described in the table, it was applied at 100,000 A / m.

  For oil resistance test, JIS No. Using an IRM 903 corresponding to oil No. 3, the volume change rate after immersion for 72 hours at 100 ° C. was used. In the table, ○ indicates ± 5% or less, and × indicates a case where ± 5% is exceeded.

Regarding the vulcanization characteristics, the degree of vulcanization was measured using a curast meter V type (manufactured by Nigo Shoji Co., Ltd.) at a temperature of 150 ° C. and a measurement time of 30 minutes. From the resulting vulcanization curve was determined scorch time t ₁₀ and proper vulcanization time t _90.

  Regarding the magnetic flux density, a magnetic encoder (outer diameter φ78 mm, inner diameter φ68 mm, magnetic rubber part thickness 1.1 mm) obtained by magnetic field molding is magnetized to 45 to 90 poles, and then magnetic property inspection apparatus TMW-EC14L (Toyo Magnetic Industry Co., Ltd.) was used to measure the magnetic flux density with a gap of 2 mm. In the table, ◯ is 12 mT or more, and x indicates a value lower than 12 mT.

  Regarding the processability, no rubber deterioration due to overheating during kneader processing and good rubber winding even during roll processing are indicated by ○ in the table, and rubber deterioration due to overheating occurs during kneading and kneading. In the table, “X” indicates that it is difficult or the rubber winding is difficult during kneading and is difficult to knead.

  Contamination characteristics of the mold are indicated by ○ in the table where there is no burrs (rubber) attached to the mold during magnetic field molding and good workability. Those with burr (rubber) adhesion and poor workability are indicated by crosses in the table.

  About adhesiveness, it evaluated by the salt water electricity test based on JISZ2371. With the aluminum plate as the positive electrode and the JIS K-6256 90 ° peeling test piece as the negative electrode, a steady current of 2 A was applied in 5% saline at 30 ° C., and rubber adhesion after 12 hours was evaluated. Regarding the evaluation of adhesiveness, there was no peeling at the adhesive interface, and the fracture at the magnetic rubber part was indicated by ◯ in the table, and the peeling at the adhesive interface was indicated by x in the table.

  Referring to Tables 1 and 2, with respect to 100 parts by weight of the solid rubber, the content of the liquid rubber is 10 parts by weight or more and 100 parts by weight or less, and the content of the internal release agent is 0.5 parts by weight or more. No. 5 parts by weight or less. 1-No. In No. 8, workability, mold contamination characteristics, and adhesiveness were good, whereas No. 8 did not satisfy the above blending ratio. 9-No. No. 20 is inferior in workability, mold contamination characteristics, or adhesiveness.

Referring to Tables 3 to 4, No. 21-No. 28, no. 32, no. In 33, both scorch time _{t 10} is 0.5 minutes or more, the proper vulcanization time _{t 90} is equal to or less than 20 minutes, it was good vulcanization properties. On the other hand, no. 29, no. 30, no. In 31, each scorch time _{t 10} is shorter than 0.5 minutes, or, appropriate vulcanization time _{t 90} is longer than 20 minutes, was poor vulcanization properties. Therefore, when good vulcanization characteristics are required, no. 21-No. 28, no. 32, no. It is preferable to select the formulation example shown in 33. In addition, No. About 33, oil resistance was inferior. Therefore, when it is used for the above-mentioned automobile, it is preferable to select one having good oil resistance.

  Referring to Tables 5 to 6, No. 34-No. 46, no. In No. 48, the magnetic flux density was 12 mT or more, and the magnetic properties were good. On the other hand, no. 49-No. For 51, the magnetic flux density was lower than 12 mT, and the magnetic properties were inferior. No. About 47, there was too much quantity of magnetic powder and the moldability was inferior. No. For No. 48, the amount of heat generated by the coil was large, and the formability in consideration of mass productivity was poor. Here, no. 39-No. In 46, since there is much content of magnetic powder, magnetic flux density can be raised more reliably. Therefore, when good magnetic properties and moldability are required, No. 39-No. It is preferable to select the formulation example shown in 46.

  A rolling bearing including such a magnetic encoder is provided in a support structure for an automobile axle. FIG. 9 is a schematic cross-sectional view showing an axle support structure. Referring to FIG. 9, axle support structure 81 includes a hub wheel 82 that rotates together with an axle (not shown), and a rolling bearing 91 that supports the axle. The flange 84 of the hub wheel 82 is fixed to a wheel (not shown) by a bolt 83. The rolling bearing 91 is a double row angular ball bearing, and includes balls 92 arranged in a double row, an inner ring 93, an outer ring 94, a retainer 95, a seal 96, and a magnetic encoder (not shown). .

  The inner ring 93 is fixed to the hub wheel 82 and rotates with the rotation of the axle. The outer ring 94 is fixed to a housing (not shown) disposed on the outer diameter side. Further, the seal 96 includes a magnetic encoder including a multipolar magnet and a slinger, and the rotation sensor 97 can detect the rotation speed.

  Thus, the axle support structure 81 is configured. Such an axle support structure 81 has good productivity.

  In addition, in said embodiment, although the case where a ball was used as a rolling element was demonstrated, it applies, also when using rollers, such as a cylindrical roller, a needle roller, and a rod roller, as a rolling element. The present invention is also applied to a rolling bearing that does not include a seal, and a rolling bearing that does not include an outer ring or an inner ring.

  Moreover, although the above-mentioned magnetic encoder was included in the rolling bearing, it may be included in not only this but a sliding bearing. Furthermore, the present invention is not limited to the rotating shaft and the like, and may be applied when detecting the rotational speed or the like of another rotating member, and may constitute a rotation detecting device that detects the rotational speed or the like of the rotating member together with the detection sensor. .

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to the thing of embodiment shown in figure. Various modifications and variations can be made to the illustrated embodiment within the same range or equivalent range as the present invention.

  The magnetic encoder and the rolling bearing according to the present invention are effectively used for a rolling bearing for an axle such as an automobile.

  Also, the method for manufacturing a magnetic encoder according to the present invention is effectively used when good productivity is required.

It is sectional drawing which shows a part of rolling bearing which concerns on one Embodiment of this invention. It is a conceptual diagram which shows the structure of a multipolar magnet. It is a schematic sectional drawing of a magnetic encoder manufacturing apparatus. It is sectional drawing of the metal mold | die core contained in a magnetic encoder manufacturing apparatus. It is a perspective view of the metal mold | die core contained in a magnetic encoder manufacturing apparatus. It is a perspective view of the lower mold core which comprises the mold core contained in a magnetic encoder manufacturing apparatus. It is a perspective view which shows the shape | molded unvulcanized magnetic rubber. It is a graph which shows the vulcanization curve of magnetic rubber. It is a schematic sectional drawing which shows the axle shaft support structure containing the rolling bearing which concerns on one Embodiment of this invention.

Explanation of symbols

  11,91 Rolling bearing, 12,92 Ball, 13,93 Inner ring, 14,94 Outer ring, 15a, 15b Raceway surface, 16 Magnetic encoder, 17,96 Seal, 21 Rotation detector, 22,97 Rotation sensor, 23 Multipole Magnet, 24, 64 Slinger, 25 Detector, 26 PCD, 27a N pole, 27b S pole, 28a, cylindrical part, 28b, 84 flange, 31 cored bar, 32 rubber part, 51 magnetic encoder manufacturing apparatus, 52 press, 53 Column, 54a Movable plate, Fixed plate 54b, 55a Movable shaft, 55b Fixed shaft, 56 Coil, 57 Cooling jacket tube, 58 Heater, 59 Thermal insulation plate, 60 Mold part, 61 Pipe, 62 Cooler, 63 Magnetic rubber, 65 surface , 71 Mold core, 72a Upper mold core, 72b Lower mold core, 73 Non-magnetic material 74 magnetic materials, 75a concave, 75b convex portion, 81 an axle support structure 82 hub wheel, 83 volts, 95 retainer.

Claims (9)

A magnetic encoder including a rubber multipole magnet in which magnetic poles are alternately arranged in a circumferential direction,
The multipolar magnet is formed by heat compression molding an unvulcanized magnetic rubber containing a rubber composition, magnetic powder, an internal release agent and a vulcanizing agent while applying a magnetic field in a predetermined direction,
The rubber composition includes a solid rubber and a liquid rubber,
The content of the liquid rubber is 10 parts by weight or more and 100 parts by weight or less with respect to 100 parts by weight of the solid rubber.
Content of the said internal mold release agent is 0.5 to 2.5 weight part with respect to 100 weight part of said solid rubbers, The magnetic encoder. The magnetic encoder according to claim 1, wherein the rubber composition includes NBR (acrylonitrile-butadiene rubber). The magnetic encoder according to claim 2, wherein the NBR includes medium-high nitrile rubber. The magnetic encoder according to claim 1 or 2, wherein the vulcanizing agent includes at least one of a peroxycide vulcanizing agent and a sulfur vulcanizing agent. The unvulcanized magnetic rubber contains a co-crosslinking agent,
The magnetic encoder according to claim 1, wherein the co-crosslinking agent includes a bismaleimide-based co-crosslinking agent. The magnetic encoder according to claim 1, wherein the magnetic rubber contains 1350 parts by weight or more of the magnetic powder with respect to 100 parts by weight of the solid rubber. The magnetic encoder according to claim 1, wherein the magnetic powder includes a ferrite magnetic powder for magnetic field orientation. A method for producing a magnetic encoder including a rubber multipole magnet having magnetic poles alternately arranged in a circumferential direction,
Solid rubber, magnetic powder in an amount of 1350 parts by weight or more with respect to 100 parts by weight of the solid rubber, liquid rubber with an amount of 10 to 100 parts by weight with respect to 100 parts by weight of the solid rubber, and 100 parts by weight of the solid rubber A step of containing an unvulcanized magnetic rubber containing an internal mold release agent and a vulcanizing agent in an amount of 0.5 to 2.5 parts by weight in the containing unit;
And a step of heat-compressing the unvulcanized magnetic rubber while applying a magnetic field in a predetermined direction to the housing portion. A rolling bearing comprising the magnetic encoder according to claim 1.

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