JP2005098475A - Rolling bearing unit for supporting wheel, and method for manufacturing the same - Google Patents

Rolling bearing unit for supporting wheel, and method for manufacturing the same Download PDF

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JP2005098475A
JP2005098475A JP2003374679A JP2003374679A JP2005098475A JP 2005098475 A JP2005098475 A JP 2005098475A JP 2003374679 A JP2003374679 A JP 2003374679A JP 2003374679 A JP2003374679 A JP 2003374679A JP 2005098475 A JP2005098475 A JP 2005098475A
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inner ring
rolling bearing
diameter side
side member
bearing unit
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JP2003374679A
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JP2005098475A5 (en
Inventor
Susumu Tanaka
進 田中
Yuji Miyamoto
裕司 宮本
Nobuaki Mitamura
宣晶 三田村
Nobuyuki Hagiwara
信行 萩原
Minoru Okamoto
実 岡本
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NSK Ltd
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NSK Ltd
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C33/00—Parts of bearings; Special methods for making bearings or parts thereof
    • F16C33/30—Parts of ball or roller bearings
    • F16C33/58—Raceways; Race rings
    • F16C33/583—Details of specific parts of races
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C43/00—Assembling bearings
    • F16C43/04—Assembling rolling-contact bearings
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C19/00—Bearings with rolling contact, for exclusively rotary movement
    • F16C19/02—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows
    • F16C19/14—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load
    • F16C19/18—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls
    • F16C19/181—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact
    • F16C19/183—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles
    • F16C19/184—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles in O-arrangement
    • F16C19/186—Bearings with rolling contact, for exclusively rotary movement with bearing balls essentially of the same size in one or more circular rows for both radial and axial load with two or more rows of balls with angular contact with two rows at opposite angles in O-arrangement with three raceways provided integrally on parts other than race rings, e.g. third generation hubs
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16C—SHAFTS; FLEXIBLE SHAFTS; ELEMENTS OR CRANKSHAFT MECHANISMS; ROTARY BODIES OTHER THAN GEARING ELEMENTS; BEARINGS
    • F16C2326/00—Articles relating to transporting
    • F16C2326/01—Parts of vehicles in general
    • F16C2326/02—Wheel hubs or castors

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Mounting Of Bearings Or Others (AREA)
  • Rolling Contact Bearings (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing for supporting a wheel, which rolling bearing can realize the structure that the delay fracture hardly occurs in an inner race 3 fitted on a hub 2 by holding down the inner race 3 by means of a caulked portion 9 formed on the hub 2. <P>SOLUTION: The hoop stress applied on the surface of the inner race 3 is set to be at most 300 MPa. Preferably, the corner portion where the outer peripheral surface of the inner race 3 crosses the end face on the side of the caulked portion 9 among both end faces of the inner race 3 in the axial direction is formed to be a convex curved surface which has a circular cross section and has the rounded-off lengths of at least 1.0 mm in the axial and radial directions respectively. Further, the hoop stress applied to the corner portion in caulking the caulked portion 9 is limited to the range from 40 to 300 MPa. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

この発明は、自動車の車輪を懸架装置に対して回転自在に支持する車輪支持用転がり軸受ユニットの改良に関する。   The present invention relates to an improvement of a rolling bearing unit for supporting a wheel that rotatably supports a wheel of an automobile with respect to a suspension device.

自動車の車輪は、車輪支持用転がり軸受ユニットにより懸架装置に支持する。この様な車輪支持用転がり軸受ユニットのうち、部品点数の削減によるコスト低減と小型・軽量化とを目的として、ハブと内輪との結合固定にナットを使用しない構造が、例えば特許文献１に記載されている様に、従来から知られている。図１〜２は、この特許文献１に記載されて従来から知られている車輪支持用転がり軸受ユニット１を示している。   The wheels of the automobile are supported on the suspension device by a rolling bearing unit for supporting the wheels. Among such rolling bearing units for supporting a wheel, for example, Patent Document 1 discloses a structure in which a nut is not used for coupling and fixing a hub and an inner ring for the purpose of reducing cost and reducing size and weight by reducing the number of parts. As it is, it is known from the past. 1 and 2 show a wheel bearing rolling bearing unit 1 described in Patent Document 1 and conventionally known.

この従来から知られている車輪支持用転がり軸受ユニット１は、ハブ２と、内輪３と、外輪４と、複数個の転動体５、５とを備える。このうちの内径側部材であるハブ２の外周面の外端（軸方向に関して外とは、自動車への組み付け状態で車両の幅方向外側を言い、図１〜４の左、図５の下。反対に、車両の幅方向中央側を軸方向に関して内と言い、図１〜４の右、図５の上。）寄り部分には、車輪を支持する為の第一のフランジ６を形成している。又、このハブ２の中間部外周面には第一の内輪軌道７を、同じく内端部には外径寸法が小さくなった段部８を、それぞれ形成している。そして、上記内輪３をこの段部８に外嵌し、更にかしめ部９により固定している。尚、上記第一の内輪軌道７は、上記ハブ２の中間部外周面に直接形成する他、このハブ２の中間部に外嵌した別体の内輪の外周面に形成する場合もある。この様な場合には、上記ハブ２の端部でこの別体の内輪よりも軸方向内方に突出した部分が、上記内輪３を外嵌する為の段部となる。   This conventionally known wheel bearing rolling bearing unit 1 includes a hub 2, an inner ring 3, an outer ring 4, and a plurality of rolling elements 5 and 5. Outer end of the outer peripheral surface of the hub 2 which is an inner diameter side member (outside with respect to the axial direction means outside in the width direction of the vehicle in the assembled state to the automobile, left of FIGS. On the contrary, the center side in the width direction of the vehicle is called inward with respect to the axial direction, and the first flange 6 for supporting the wheel is formed on the right side of FIGS. Yes. A first inner ring raceway 7 is formed on the outer peripheral surface of the intermediate portion of the hub 2, and a step portion 8 having a smaller outer diameter is formed on the inner end portion. The inner ring 3 is externally fitted to the step portion 8 and further fixed by a caulking portion 9. The first inner ring raceway 7 may be formed directly on the outer peripheral surface of the intermediate portion of the hub 2 or may be formed on the outer peripheral surface of a separate inner ring that is externally fitted to the intermediate portion of the hub 2. In such a case, the portion of the end portion of the hub 2 that protrudes inward in the axial direction from the separate inner ring is a stepped portion for fitting the inner ring 3 outwardly.

又、上記ハブ２の内端部に、このかしめ部９を構成する為の円筒部１０を形成している。この円筒部１０の肉厚は、図３に示した、この円筒部１０を直径方向外方にかしめ広げる以前の状態で、先端縁に向かう程小さくなっている。この為上記ハブ２の内端面に、奥部に向かう程次第に内径が小さくなるテーパ孔１１を形成している。又、このハブ２は、上記円筒部１０を上記かしめ部９に加工する為の塑性加工が容易で、且つ上記第一の内輪軌道７等の必要部分の硬度を高周波焼き入れ等により十分に高くする事が可能な、Ｓ５３Ｃ、Ｓ５５Ｃ等の機械構造用炭素鋼により造っている。これに対して上記内輪３は、上記かしめ部９の加工に伴って加わる応力に対し十分な強度を有し、且つ、十分な転がり疲労寿命を有する、ＳＵＪ２、ＳＵＪ３等の高炭素クロム軸受鋼を、主として使用する。   A cylindrical portion 10 for forming the caulking portion 9 is formed at the inner end portion of the hub 2. The thickness of the cylindrical portion 10 is smaller toward the tip edge in the state before the cylindrical portion 10 is caulked outward in the diametrical direction as shown in FIG. For this reason, a tapered hole 11 is formed in the inner end surface of the hub 2 such that the inner diameter gradually decreases toward the inner part. The hub 2 is easy to plastically process the cylindrical portion 10 into the caulking portion 9, and the hardness of a necessary portion such as the first inner ring raceway 7 is sufficiently high by induction hardening or the like. It is made of carbon steel for mechanical structures such as S53C and S55C. On the other hand, the inner ring 3 is made of a high carbon chrome bearing steel such as SUJ2 or SUJ3 that has sufficient strength against stress applied in connection with the caulking portion 9 and has a sufficient rolling fatigue life. , Mainly used.

上記ハブ２の内端部に上記内輪３を固定すべく、上述の様な円筒部１０の先端部をかしめ広げるには、上記ハブ２が軸方向にずれ動かない様に固定した状態で、図２に示す様に、押型１２を上記円筒部１０の先端部に強く押し付ける。この押型１２の先端面（図２の左端面）中央部には、上記円筒部１０の内側に押し込み自在な円錐台状の凸部１３を形成し、この凸部１３の周囲に断面円弧状の凹部１４を、この凸部１３の全周を囲む状態で形成している。尚、この凹部１４の断面形状は、この凹部１４により上記円筒部１０の先端部を塑性変形させる事で得られるかしめ部９の断面形状が、基端部から先端部に向かう程厚さ寸法が漸次小さくなり、特にこの厚さ寸法が先端部で急激に小さくなる様に、外径側に向かう程曲率半径が小さくなる複合曲面としている。   In order to squeeze the tip of the cylindrical portion 10 as described above in order to fix the inner ring 3 to the inner end of the hub 2, the hub 2 is fixed so as not to move in the axial direction. As shown in FIG. 2, the pressing die 12 is strongly pressed against the tip portion of the cylindrical portion 10. A frustoconical convex portion 13 that can be pushed into the inside of the cylindrical portion 10 is formed at the center of the tip surface (left end surface in FIG. 2) of the pressing die 12, and a circular arc section is formed around the convex portion 13. The concave portion 14 is formed so as to surround the entire circumference of the convex portion 13. Note that the cross-sectional shape of the concave portion 14 is such that the cross-sectional shape of the caulking portion 9 obtained by plastically deforming the distal end portion of the cylindrical portion 10 by the concave portion 14 is such that the thickness dimension increases from the proximal end portion toward the distal end portion. The composite curved surface is gradually reduced, and in particular, the curvature radius decreases toward the outer diameter side so that the thickness dimension decreases rapidly at the tip.

上述の様な形状並びに寸法の凸部１３と凹部１４とを有する押型１２を上記円筒部１０の先端部に押し付ければ、この円筒部１０の先端部を直径方向外方にかしめ広げて、上記かしめ部９を形成する事ができる。そして、このかしめ部９とハブ２の内端部に形成した段部８の段差面１５との間で上記内輪３を挟持して、この内輪３を上記ハブ２に固定できる。   If the pressing die 12 having the convex portion 13 and the concave portion 14 having the shape and dimensions as described above is pressed against the tip portion of the cylindrical portion 10, the tip portion of the cylindrical portion 10 is caulked outward in the diametrical direction, The caulking portion 9 can be formed. The inner ring 3 can be clamped between the caulking portion 9 and the step surface 15 of the step portion 8 formed at the inner end portion of the hub 2, and the inner ring 3 can be fixed to the hub 2.

一方、外径側部材である前記外輪４の内周面には、上記ハブ２の中間部外周面に形成した第一の内輪軌道７と対向する第一の外輪軌道１６、及び、上記内輪３の外周面に形成した第二の内輪軌道１７に対向する第二の外輪軌道１８を形成している。そして、これら第一、第二の内輪軌道７、１７と第一、第二の外輪軌道１６、１８との間に前記転動体５、５を、それぞれ保持器１９、１９により転動自在に保持した状態で、複数個ずつ設けている。尚、図示の例では、転動体５、５として玉を使用しているが、重量の嵩む自動車用の転がり軸受ユニットの場合には、これら転動体としてテーパころを使用する場合もある。上述の様な車輪支持用転がり軸受ユニット１を自動車に組み付けるには、上記外輪４の外周面に形成した第二のフランジ２０により、この外輪４を懸架装置に固定し、上記第一のフランジ６に車輪を固定する。この結果、この車輪を懸架装置に対し回転自在に支持する事ができる。   On the other hand, on the inner peripheral surface of the outer ring 4 which is an outer diameter side member, the first outer ring raceway 16 facing the first inner ring raceway 7 formed on the outer peripheral surface of the intermediate portion of the hub 2, and the inner ring 3. A second outer ring raceway 18 is formed opposite to the second inner ring raceway 17 formed on the outer peripheral surface of the first outer ring raceway. The rolling elements 5 and 5 are held between the first and second inner ring raceways 7 and 17 and the first and second outer ring raceways 16 and 18 by the retainers 19 and 19, respectively. In this state, a plurality are provided. In the illustrated example, balls are used as the rolling elements 5 and 5. However, in the case of a rolling bearing unit for automobiles that is heavy in weight, tapered rollers may be used as these rolling elements. In order to assemble the wheel bearing rolling bearing unit 1 as described above to an automobile, the outer ring 4 is fixed to the suspension device by the second flange 20 formed on the outer peripheral surface of the outer ring 4, and the first flange 6. Secure the wheels to the As a result, this wheel can be rotatably supported with respect to the suspension device.

尚、図４に示す様に、外輪回転型の車輪支持用転がり軸受ユニット１ａの場合にも、かしめ部９ａにより内輪３ａを固定する構造がある。この車輪支持用転がり軸受ユニット１ａの場合、外径側部材であるハブ２ａの外端寄り部外周面に、車輪を支持固定する為の第一のフランジ６ａを設けている。又、このハブ２ａの内端部内周面には第一の外輪軌道１６ａを、中間部内周面には第二の外輪軌道１８ａを、それぞれ形成している。又、このハブ２ａの直径方向内側に設けた、内径側部材である軸部材２１の内端部に、懸架装置に固定する為の第二のフランジ２０ａを設けている。又、この軸部材２１の外周面で中間部内端寄り部分に、第一の内輪軌道７ａを直接形成すると共に、外端部に形成した段部８ａに、外周面に第二の内輪軌道１７ａを形成した上記内輪３ａを外嵌している。そして、上記軸部材２１の外端部でこの内輪３ａよりも軸方向外方に突出した部分に形成した円筒部１０ａを直径方向外方にかしめ広げる事で形成した上記かしめ部９ａにより、上記軸部材２１に外嵌した内輪３ａをこの軸部材２１に結合固定している。   As shown in FIG. 4, the outer ring rotating type wheel bearing rolling bearing unit 1a also has a structure in which the inner ring 3a is fixed by the caulking portion 9a. In the case of this wheel support rolling bearing unit 1a, a first flange 6a for supporting and fixing a wheel is provided on the outer peripheral surface of the outer end portion of the hub 2a which is an outer diameter side member. A first outer ring raceway 16a is formed on the inner peripheral surface of the inner end portion of the hub 2a, and a second outer ring raceway 18a is formed on the inner peripheral surface of the intermediate portion. Further, a second flange 20a for fixing to the suspension device is provided at the inner end portion of the shaft member 21, which is an inner diameter side member, provided inside the hub 2a in the diameter direction. Further, the first inner ring raceway 7a is directly formed on the outer peripheral surface of the shaft member 21 near the inner end of the intermediate portion, and the second inner ring raceway 17a is formed on the outer peripheral surface of the step portion 8a formed on the outer end portion. The formed inner ring 3a is externally fitted. And, by the caulking portion 9a formed by caulking and expanding the cylindrical portion 10a formed on the outer end portion of the shaft member 21 in the axially outward direction from the inner ring 3a, the shaft An inner ring 3 a that is externally fitted to the member 21 is coupled and fixed to the shaft member 21.

又、上述の様に構成し作用する車輪支持用転がり軸受ユニット１、１ａを造るべく、前記円筒部１０、１０ａを塑性変形させて（かしめ広げて）前記かしめ部９、９ａを形成する作業を行なうのに好ましくは、図５に示す様な揺動プレス装置２２を使用する。この揺動プレス装置２２は、押型１２と、抑え治具２３と、ホルダ２４とを備える。図示の例は、図１に示した車輪支持用転がり軸受ユニット１を、上記揺動プレス装置２２に組み込んだ状態を示している。尚、内輪３ｂの形状は、上記図１に示した構造と異ならせている。即ち、この内輪３ｂは、内端面の外径側半部を軸方向に凹ませて、内端部を段付形状としている。上記円筒部１０をかしめ広げて上記かしめ部９を形成する際には、上記ホルダ２４を介してハブ２を上方に押圧しつつ、上記押型１２を揺動変位させる。即ち、この押型１２の中心軸と上記ハブ２の中心軸とを角度θだけ傾斜させた状態で、この押型１２を、このハブ２の中心軸を中心として揺動変位させる。   Further, in order to produce the wheel bearing rolling bearing units 1 and 1a configured and operated as described above, an operation of plastically deforming (caulking and expanding) the cylindrical portions 10 and 10a to form the caulking portions 9 and 9a is performed. Preferably, a oscillating press 22 as shown in FIG. 5 is used. The swing press device 22 includes a pressing die 12, a holding jig 23, and a holder 24. The illustrated example shows a state in which the wheel bearing rolling bearing unit 1 shown in FIG. The shape of the inner ring 3b is different from the structure shown in FIG. That is, the inner ring 3b has a half portion on the outer diameter side of the inner end surface recessed in the axial direction, and the inner end portion has a stepped shape. When the caulking portion 9 is formed by caulking the cylindrical portion 10, the pressing die 12 is oscillated and displaced while pressing the hub 2 upward via the holder 24. That is, in a state where the central axis of the pressing die 12 and the central axis of the hub 2 are inclined by an angle θ, the pressing die 12 is oscillated and displaced about the central axis of the hub 2.

この様な揺動プレスにより上記かしめ部９を形成する際には、上記押型１２の円周方向の一部が上記円筒部１０を押圧する事になり、上記かしめ部９の加工作業は部分的に且つ円周方向に連続して進行する事になる。この為、一般的な鍛造加工により上記かしめ部９を形成する場合に比べて、加工時に上記円筒部１０に加える荷重を小さくできる。尚、上記抑え治具２３は、上記押型１２によるかしめ部９の加工時に内輪３及び上記ハブ２が径方向に振れる事を防止する。   When the caulking portion 9 is formed by such a rocking press, a part of the pressing die 12 in the circumferential direction presses the cylindrical portion 10, and the working operation of the caulking portion 9 is partially performed. And continuously in the circumferential direction. For this reason, compared with the case where the said caulking part 9 is formed by a general forging process, the load added to the said cylindrical part 10 at the time of a process can be made small. The holding jig 23 prevents the inner ring 3 and the hub 2 from swinging in the radial direction when the caulking portion 9 is processed by the pressing die 12.

又、図４に示した様な、外輪回転型の上記車輪支持用転がり軸受ユニット１ａのかしめ部９ａを形成する場合には、この車輪支持用転がり軸受ユニット１ａを揺動プレス装置２２に、上述した場合と軸方向に関して逆に設置する。そして、抑え治具２３により内輪３ａ及び軸部材２１を固定し、この軸部材２１の外端部に設けた円筒部１０ａを押型１２によりかしめ広げる事で、上記かしめ部９ａを形成する。   When the caulking portion 9a of the wheel support rolling bearing unit 1a of the outer ring rotating type as shown in FIG. 4 is formed, the wheel supporting rolling bearing unit 1a is connected to the swing press device 22 as described above. Install in the opposite direction with respect to the axial direction. Then, the inner ring 3 a and the shaft member 21 are fixed by the holding jig 23, and the cylindrical portion 10 a provided at the outer end portion of the shaft member 21 is caulked and spread by the pressing die 12, thereby forming the caulking portion 9 a.

上述の様にかしめ部９、９ａを形成する際に無理な力が加わった場合等に、亀裂等の損傷が発生する場合がある。このかしめ部９、９ａの形成に伴う亀裂等の損傷の発生を防ぐ為、例えば、特許文献２〜３に記載されている様な技術がある。このうちの特許文献２に記載された技術では、内輪の端部内周面に傾斜面を形成する事により、かしめ部を形成すべき円筒部の変形量を小さくして、かしめ作業に伴って無理な力が加わりにくくしている。又、特許文献３に記載された技術では、かしめ部を形成すべき円筒部を構成する炭素鋼の結晶粒の平均断面を小さくして、かしめ部の形成に伴って亀裂等の損傷が発生する事を防止している。   As described above, damage such as cracks may occur when an excessive force is applied when the caulking portions 9 and 9a are formed. In order to prevent the occurrence of damage such as cracks associated with the formation of the caulking portions 9 and 9a, for example, there are techniques as described in Patent Documents 2 to 3. In the technique described in Patent Literature 2 among these, by forming an inclined surface on the inner peripheral surface of the end portion of the inner ring, the amount of deformation of the cylindrical portion where the caulking portion should be formed is reduced, and it is impossible to perform the caulking operation. It is difficult to apply extra power. Further, in the technique described in Patent Document 3, the average cross section of the crystal grains of the carbon steel constituting the cylindrical portion where the caulking portion is to be formed is reduced, and damage such as a crack occurs with the formation of the caulking portion. To prevent things.

上記特許文献２〜３に記載された従来技術は、上記かしめ部９、９ａを含むハブ２或は軸部材２１に亀裂等の損傷が発生するのを防止する事を意図している。但し、十分な耐久性及び信頼性を有する車輪支持用転がり軸受ユニットを得る為には、上記かしめ部９、９ａによりその端面を抑え付けられる内輪３、３ａ、３ｂに関しても、損傷防止の為の配慮を行なう必要がある。即ち、上記かしめ部９、９ａの加工に伴って上記内輪３、３ａ、３ｂには、大きなフープ応力（円周方向の引っ張り力）が加わる。そして、この内輪３、３ａ、３ｂの形状が不適正であったり、或は上記フープ応力が過大である場合には、この内輪３、３ａ、３ｂに亀裂が発生する。一方、前記ハブ２或は前記軸部材２１に対するこの内輪３、３ａ、３ｂの支持強度を確保する為には、上記フープ応力を或る程度大きくする事は避けられない。又、上記かしめ部９、９ａを形成した後の状態で上記内輪３、３ａ、３ｂには、前記転動体５、５に予圧を付与する事に伴い、上記フープ応力に加えて、軸方向に関する圧縮応力も加わる。   The conventional techniques described in Patent Documents 2 and 3 are intended to prevent the occurrence of damage such as cracks in the hub 2 or the shaft member 21 including the caulking portions 9 and 9a. However, in order to obtain a wheel bearing rolling bearing unit having sufficient durability and reliability, the inner rings 3, 3a, 3b whose end faces are suppressed by the caulking portions 9, 9a are also used for preventing damage. It is necessary to give consideration. That is, a large hoop stress (a tensile force in the circumferential direction) is applied to the inner rings 3, 3a, 3b as the caulking portions 9, 9a are processed. If the shapes of the inner rings 3, 3a, 3b are inappropriate or the hoop stress is excessive, cracks occur in the inner rings 3, 3a, 3b. On the other hand, in order to ensure the supporting strength of the inner rings 3, 3a, 3b with respect to the hub 2 or the shaft member 21, it is inevitable that the hoop stress is increased to some extent. Further, in addition to the hoop stress, the inner ring 3, 3a, 3b is applied with a preload to the inner rings 3, 3a, 3b after the caulking portions 9, 9a are formed. Compressive stress is also applied.

ところで、一般に、高炭素クロム軸受鋼の如き高強度鋼等の高強度材料により造られた部材に大きな荷重を付加すると、遅れ破壊と呼ばれる現象が発生する事が、従来から知られている。この遅れ破壊と呼ばれる現象は、当該部材の破損が荷重を付加した後直ちには発生せず、荷重が負荷されてから相当時間経過後に突然破壊する現象で、特に、引っ張り強度が１．２ＧＰａ以上、硬さがＨＲＣ４０以上の高強度材料の場合に、遅れ破壊感受性（遅れ破壊の発生し易さ）が増加するとされている。又、遅れ破壊強度は、水分の存在下で低下する（遅れ破壊が発生し易くなる）事も、従来から知られている。例えば、非特許文献１には、引っ張り強度が１．５〜２ＧＰａ程度の高強度鋼の場合、水中に１００時間浸漬した場合の遅れ破壊強度は、乾燥下での同強度に比べて１／３〜１／４にまで低下する事が記載されている。   By the way, it is conventionally known that when a large load is applied to a member made of a high strength material such as high strength steel such as high carbon chromium bearing steel, a phenomenon called delayed fracture occurs. This phenomenon called delayed fracture does not occur immediately after the load is applied, but suddenly breaks after a lapse of time after the load is applied. Particularly, the tensile strength is 1.2 GPa or more, In the case of a high-strength material having a hardness of HRC 40 or higher, delayed fracture susceptibility (ease of delayed fracture) increases. It has also been conventionally known that delayed fracture strength decreases in the presence of moisture (delayed fracture tends to occur). For example, in Non-Patent Document 1, in the case of a high strength steel having a tensile strength of about 1.5 to 2 GPa, the delayed fracture strength when immersed in water for 100 hours is 1/3 compared to the same strength under drying. It is described that it decreases to ˜¼.

本発明の対象となる車輪支持用転がり軸受ユニットの場合、ハブ２或は軸部材２１に外嵌した内輪３、３ａは、従動輪用の車輪支持用転がり軸受ユニット場合には外輪４或はハブ２ａの開口端部を塞いだカバー２５（図１参照、図４には省略）により、駆動輪用の車輪支持用転がり軸受ユニットの場合にはシールリング（図示省略）により、それぞれ外部空間と遮断されている。従って、基本的には、上記内輪３、３ａに雨水等の水分が付着する事はないが、長期間に亙る使用に伴って上記外輪４或はハブ２ａと上記カバー２５との間の微小隙間から水が侵入したり、或は上記シールリングのシール性が低下した場合には、上記内輪３、３ａに水分が付着する可能性を完全に否定する事はできない。又、コスト低減及び重量軽減を考慮した場合、上記カバー２５を省略する事も考えられ、この場合には、上記内輪３、３ａに水分が付着する事は避けられない。   In the case of a wheel bearing rolling bearing unit that is the subject of the present invention, the inner ring 3, 3a fitted on the hub 2 or the shaft member 21 is the outer ring 4 or hub in the case of a wheel supporting rolling bearing unit for a driven wheel. A cover 25 (see FIG. 1 and omitted in FIG. 4) that closes the opening end of 2a, and in the case of a wheel support rolling bearing unit for driving wheels, a seal ring (not shown) is used to shut off the external space. Has been. Therefore, basically, water such as rainwater does not adhere to the inner rings 3 and 3a, but a minute gap between the outer ring 4 or the hub 2a and the cover 25 with use over a long period of time. If water enters from the inside or the sealing performance of the seal ring is lowered, the possibility of moisture adhering to the inner rings 3, 3a cannot be completely denied. In consideration of cost reduction and weight reduction, the cover 25 may be omitted. In this case, it is inevitable that moisture adheres to the inner rings 3 and 3a.

何れにしても、この内輪３、３ａに、遅れ破壊に基づく亀裂等の損傷が発生した場合、車輪支持用転がり軸受ユニットの運転時に大きな振動が発生し、この車輪支持用転がり軸受ユニットを組み込んだ自動車が早期に走行不能になる可能性がある。この様な事情を考慮した場合、図１、４に記載した様に、ハブ２或は軸部材２１に外嵌した内輪３、３ａをかしめ部９、９ａにより抑え付ける構造の耐久性をより一層向上させる為に、この内輪３、３ａに遅れ破壊が発生しにくい構造を実現する事が必要になる。   In any case, when damage such as cracks due to delayed fracture occurs in the inner rings 3, 3a, a large vibration is generated during operation of the wheel support rolling bearing unit, and this wheel support rolling bearing unit is incorporated. The car may become unable to run early. In consideration of such circumstances, as shown in FIGS. 1 and 4, the durability of the structure in which the inner ring 3, 3 a externally fitted to the hub 2 or the shaft member 21 is suppressed by the caulking portions 9, 9 a is further increased. In order to improve, it is necessary to realize a structure in which the inner ring 3, 3a is less likely to cause delayed fracture.

上記内輪３、３ａに遅れ破壊に結び付く様なフープ応力が生じる事を防止する為の技術として従来から、特許文献４、５に記載されたものが知られている。これら各特許文献に記載された従来技術は、かしめ部に加工する為の円筒部の先半部外周面に小径部を形成し、この小径部の端部を上記内輪の端面よりもこの内輪の中間寄りに位置させるものである。この様な構成を採用する事で、上記円筒部の径を広げた場合に上記内輪に加わるフープ応力を、或る程度小さくできる。この様な特許文献４、５に記載された従来技術によれば、上記内輪の端部に生じるフープ応力の低減を図れるが、それだけでは、この内輪に関する遅れ破壊の防止効果が必ずしも十分とは言えない。何となれば、上記特許文献４、５に記載された技術により、上記内輪の端部に加わるフープ応力の低減を図れても、この部分に、遅れ破壊の防止効果が大きい圧縮応力を生じさせる事はできない。又、上記特許文献４、５には、上記内輪の端部に生じるフープ応力をどの程度に抑えれば、上記遅れ破壊を十分に防止できるかは開示されていない。従って、上記特許文献４、５に記載された技術を採用したとしても、円筒部をかしめ部を加工する際に、この円筒部に加える荷重を適正に規制しない限り、上記遅れ破壊を十分に防止できない。   Conventionally, the techniques described in Patent Documents 4 and 5 are known as techniques for preventing the hoop stress that may cause delayed fracture in the inner rings 3 and 3a. In the prior art described in each of these patent documents, a small-diameter portion is formed on the outer peripheral surface of the front half of the cylindrical portion for processing into the caulking portion, and the end portion of the small-diameter portion is made closer to the inner ring than the end surface of the inner ring. It is located near the middle. By adopting such a configuration, the hoop stress applied to the inner ring when the diameter of the cylindrical portion is increased can be reduced to some extent. According to such conventional techniques described in Patent Documents 4 and 5, it is possible to reduce the hoop stress generated at the end portion of the inner ring. However, it is not always sufficient to prevent delayed fracture related to the inner ring. Absent. Even if the hoop stress applied to the end portion of the inner ring can be reduced by the techniques described in Patent Documents 4 and 5, a compressive stress having a large effect of preventing delayed fracture is generated in this portion. I can't. Further, Patent Documents 4 and 5 do not disclose how much the hoop stress generated at the end of the inner ring can be suppressed to sufficiently prevent the delayed fracture. Therefore, even when the techniques described in Patent Documents 4 and 5 are adopted, the delayed fracture is sufficiently prevented unless the load applied to the cylindrical portion is properly regulated when the caulking portion is processed into the cylindrical portion. Can not.

特開平１１−１２９７０３号公報JP-A-11-129703 特開平１０−９５２０３号公報JP-A-10-95203 特開２００１−２３９８０３号公報JP 2001-239803 A 特開２００２−１３９０６０号公報JP 2002-139060 A 特開２００１−１３０２１０号公報JP 2001-130210 A 松山晋作、「遅れ破壊」、日刊工業新聞社、１９８９年８月３１日、Ｐ．６７、図４．１Matsuyama, Sakusaku, “Delayed Destruction”, Nikkan Kogyo Shimbun, August 31, 1989, p. 67, FIG. 4.1

本発明は、上述の様な事情に鑑みて、ハブ或は軸部材等の内径側部材に外嵌した内輪を、この内径側部材に形成したかしめ部により抑え付ける構造で、この内輪に遅れ破壊が発生しにくい構造を実現すべく発明したものである。   In view of the circumstances as described above, the present invention has a structure in which an inner ring externally fitted to an inner diameter side member such as a hub or a shaft member is suppressed by a caulking portion formed on the inner diameter side member. The invention has been invented to realize a structure in which the occurrence of such a phenomenon is difficult to occur.

本発明の車輪支持用転がり軸受ユニットは何れも、外周面に第一の内輪軌道を一体又は別体の内輪を介して有する内径側部材と、この内径側部材の端部に外嵌された、外周面に第二の内輪軌道を有する鋼製の内輪と、内周面にこれら第一、第二の内輪軌道に対向する第一、第二の外輪軌道を有する外径側部材と、これら第一、第二の内輪軌道とこれら第一、第二の外輪軌道との間に、それぞれ複数個ずつ設けられた転動体とを備える。そして、上記内径側部材の端部で少なくともこの内径側部材に外嵌した内輪よりも突出した部分に形成した円筒部を直径方向外方にかしめ広げる事で形成したかしめ部により、上記内径側部材に外嵌した内輪をこの内径側部材に結合固定している。   Each of the rolling bearing units for supporting a wheel of the present invention is externally fitted to the inner diameter side member having the first inner ring raceway on the outer peripheral surface through an integral or separate inner ring, and the end of the inner diameter side member. A steel inner ring having a second inner ring raceway on the outer peripheral surface, outer diameter side members having first and second outer ring raceways opposed to the first and second inner ring raceways on the inner peripheral surface, and A plurality of rolling elements are provided between each of the first and second inner ring raceways and the first and second outer ring raceways. Then, the inner diameter side member is formed by a caulking portion formed by caulking and expanding the cylindrical portion formed at least at the end portion of the inner diameter side member and projecting from the inner ring externally fitted to the inner diameter side member. The inner ring fitted on the inner side is coupled and fixed to the inner diameter side member.

そして、請求項１に記載した車輪支持用転がり軸受ユニットに於いては、上記かしめ部の加工に伴って上記内輪の表面に加わるフープ応力を３００ＭＰａ以下としている。
又、請求項２に記載した車輪支持用転がり軸受ユニットに於いては、上記内輪の外周面と、この内輪の軸方向両端面のうちで上記かしめ部が設けられた側の端面とが交差する角部に、上記かしめ部の加工に伴って上記角部に加わるフープ応力を、３００ＭＰａ以下としている。
更に、請求項４に記載した車輪支持用転がり軸受ユニットに於いては、上記内輪の軸方向両端面のうちで上記かしめ部が設けられた側の端面のうちの少なくとも一部分（好ましくは全周）に、円周方向の残留圧縮応力が存在する。尚、この端面に圧縮応力を残留させる為には、上記内輪に施す熱処理工程と研削工程との加工条件を適宜選定する。そして、この内輪の端面をかしめ部で抑え付ける以前の、この内輪単体の端面、この端面の周縁部に形成した面取り部に、円周方向の強い圧縮応力を残留させる。 In the wheel support rolling bearing unit according to the first aspect, the hoop stress applied to the surface of the inner ring as the caulking portion is processed is set to 300 MPa or less.
In the wheel support rolling bearing unit according to claim 2, the outer peripheral surface of the inner ring and the end surface on the side where the caulking portion is provided among the axial end surfaces of the inner ring intersect. At the corner, the hoop stress applied to the corner as the caulking portion is processed is set to 300 MPa or less.
Furthermore, in the rolling bearing unit for supporting a wheel according to claim 4, at least a part (preferably the entire circumference) of the end face on the side where the caulking portion is provided among the axial end faces of the inner ring. In addition, there is a residual compressive stress in the circumferential direction. In order to leave compressive stress on the end face, the processing conditions for the heat treatment process and the grinding process applied to the inner ring are appropriately selected. Then, strong compressive stress in the circumferential direction remains on the end surface of the inner ring alone and the chamfered portion formed on the peripheral edge of the end surface before the end surface of the inner ring is suppressed by the caulking portion.

上述の様に構成する本発明によれば、かしめ部により抑え付けられた鋼製の内輪に遅れ破壊が発生しにくくして、車輪支持用転がり軸受ユニットの耐久性をより一層向上させる事ができる。
即ち、本発明者は、腐食環境下で、それぞれ残留応力が異なる複数種類の車輪支持用転がり軸受ユニットの耐久性に関する試験を行ない、内輪の表面にどの程度のフープ応力 が残留した場合に、遅れ破壊が生じるのかを評価した。その結果、このフープ応力が４００〜８００ＭＰａになると、遅れ破壊が生じる可能性が高くなる事が分かった。尚、このフープ応力が８００ＭＰａを越えると、腐蝕環境下でなくても破壊（遅れ破壊でなく、通常の破壊）が生じる可能性が高くなる。
これに対して請求項１、２に記載した発明の場合には、上記フープ応力を３００ＭＰａ以下に抑えているので、上記内輪に、一般的な破壊は勿論、遅れ破壊が生じる事も十分に防止できる。 According to the present invention configured as described above, delayed fracture is less likely to occur in the steel inner ring suppressed by the caulking portion, and the durability of the wheel bearing rolling bearing unit can be further improved. .
In other words, the present inventor conducted tests on the durability of a plurality of types of wheel bearing rolling bearing units each having different residual stresses in a corrosive environment, and the amount of hoop stress remaining on the inner ring surface was delayed. It was evaluated whether destruction occurred. As a result, it has been found that when this hoop stress is 400 to 800 MPa, the possibility of delayed fracture increases. When the hoop stress exceeds 800 MPa, there is a high possibility that breakage (ordinary breakage, not delayed breakage) occurs even in a corrosive environment.
On the other hand, in the case of the invention described in claims 1 and 2, since the hoop stress is suppressed to 300 MPa or less, it is possible to sufficiently prevent the inner ring from causing delayed fracture as well as general fracture. it can.

更に、請求項４に記載した発明の様に、かしめ部を設けた側の内輪の端面に円周方向の残留圧縮応力が存在させれば、仮に亀裂等の損傷が発生しても、この残留圧縮応力が、この損傷を塞ぐ方向の力として加わる。この為、上記一般的な破壊は勿論、遅れ破壊が生じる事もより確実に防止できる。
即ち、上記かしめ部によりその端面を抑え付ける以前の、内輪単体の状態で、この内輪の端面に強い圧縮応力を残留させておけば、この内輪の端面をかしめ部により抑え付けた以後の状態でも、この内輪の端面に圧縮応力を残留させる事ができる。上記かしめ部の加工条件によっては、この内輪の端面の圧縮応力が一部若しくは全周に亙って消滅し、消滅した部分にフープ応力が生じる場合もあるが、その場合でも、このフープ応力を３００ＭＰａ以下に抑える事は容易である。即ち、上記請求項４に記載した発明を実施しようとして、上記内輪の端面に残留させた圧縮応力が消滅したとしても、上記請求項１、２の発明を確実に実施できる。従って、上記内輪の熱処理工程及び研削工程の条件を適切に選定する事で、腐食環境下でも、亀裂が発生せず、仮に、ミクロの亀裂が発生したとしても、この亀裂がマクロの亀裂に進展しない構造を実現できる。 Further, if residual compressive stress in the circumferential direction is present on the end face of the inner ring on the side where the caulking portion is provided as in the invention described in claim 4, even if damage such as cracks occurs, this residual Compressive stress is applied as a force in the direction of closing this damage. For this reason, it is possible to more surely prevent the above-mentioned general destruction and delayed destruction.
That is, if a strong compressive stress is left on the end surface of the inner ring in the state of the inner ring alone before the end surface is suppressed by the caulking portion, the state after the end surface of the inner ring is suppressed by the caulking portion is also possible. Compressive stress can remain on the end face of the inner ring. Depending on the processing conditions of the caulking part, the compressive stress of the end face of the inner ring may disappear over a part or all of the circumference, and a hoop stress may be generated in the disappeared part. It is easy to keep the pressure below 300 MPa. That is, even if the compressive stress remaining on the end face of the inner ring disappears in an attempt to implement the invention described in claim 4, the inventions of claims 1 and 2 can be reliably implemented. Therefore, by appropriately selecting the conditions for the heat treatment process and grinding process for the inner ring, cracks do not occur even in a corrosive environment, and even if micro cracks occur, these cracks will develop into macro cracks. Can be realized.

因に、熱処理工程、研削工程で初期残留圧縮応力が無い場合には、上記かしめ部の加工に伴って上記内輪に径方向外方に加わる力が、そのままフープ応力となる。従って、かしめ加工以前に内輪の端面に圧縮応力を残留させない場合には、かしめ加工後にこの内輪の端面に加わるフープ応力を３００ＭＰａ以下に抑える為、このかしめ加工の条件設定に厳密さを要求される事になる。   Incidentally, when there is no initial residual compressive stress in the heat treatment step and the grinding step, the force applied radially outward to the inner ring as the caulking portion is processed becomes the hoop stress as it is. Therefore, when compressive stress does not remain on the end face of the inner ring before caulking, the hoop stress applied to the end face of the inner ring after caulking is suppressed to 300 MPa or less. It will be a thing.

尚、上記熱処理工程で発生する残留応力は、変態応力と熱応力との２種類の応力に基づくものである。本発明を実施する場合に影響のある変態応力は、オーステナイト（ＦＣＣ）→マルテンサイト（ＢＣＣ）変態の為、表面が残留引っ張り応力になる。これに対して熱応力は、熱収縮が表面から内部へと変化する為、表面が圧縮の残留応力になる。従って、本発明を実施する場合には、内輪形状、内輪材質、熱処理条件を適切に選定する事により、熱応力が変態応力に勝る条件を設定し、表面に圧縮応力を残留させる。   The residual stress generated in the heat treatment process is based on two types of stress, transformation stress and thermal stress. The transformation stress that affects the implementation of the present invention is the austenite (FCC) → martensite (BCC) transformation, so that the surface becomes a residual tensile stress. On the other hand, the thermal stress changes from the surface to the inside, so that the surface becomes a compressive residual stress. Therefore, when carrying out the present invention, by appropriately selecting the inner ring shape, the inner ring material, and the heat treatment conditions, a condition that the thermal stress exceeds the transformation stress is set, and the compressive stress remains on the surface.

又、研削工程で発生する残留応力は、「砥粒の切削作用」、「砥粒のバニッシュ作用」、「熱の作用」の３種類の作用に基づくものである。このうちの「砥粒の切削作用」及び「熱の作用」は、残留引っ張り応力に結び付く。特に、この砥粒の切れが悪い（砥粒の角部が鋭利でなく、切削抵抗が大きい場合）場合には、残留引っ張り応力が大きくなる。これに対して、「砥粒のバニッシュ作用」は、残留圧縮応力になる。従って、研削の条件を適切に選定すれば、「砥粒の切削作用」に基づく引っ張り応力が小さくなり、「砥粒のバニッシュ作用」に基づく圧縮応力が勝り、研削加工後の内輪に圧縮応力を残留させる事ができる。尚、熱の影響は、冷却によってできる限り小さくする。   Further, the residual stress generated in the grinding process is based on three types of actions: “abrasive cutting action”, “abrasive burnishing action”, and “thermal action”. Of these, “the cutting action of the abrasive grains” and “the action of heat” are related to the residual tensile stress. In particular, when the abrasive grains are poorly cut (when the corners of the abrasive grains are not sharp and the cutting resistance is large), the residual tensile stress increases. On the other hand, the “burnishing action of abrasive grains” becomes residual compressive stress. Accordingly, if the grinding conditions are properly selected, the tensile stress based on the “abrasive cutting action” is reduced, the compressive stress based on the “abrasive action of abrasive grains” is superior, and the compressive stress is applied to the inner ring after grinding. It can be left. The influence of heat is minimized as much as possible by cooling.

請求項２に記載した発明を実施する場合に好ましくは、請求項３に記載した様に、内輪の外周面と、この内輪の軸方向両端面のうちでかしめ部が設けられた側の端面とが交差する角部を、断面形状が円弧形で軸方向寸法及び径方向寸法が何れも１．０mm以上である凸曲面とし、且つ、上記かしめ部の加工に伴って上記角部に加わるフープ応力を４０〜３００ＭＰａの範囲に規制する。   When the invention described in claim 2 is carried out, preferably, as described in claim 3, the outer peripheral surface of the inner ring and the end surface on the side where the caulking portion is provided among the axial end surfaces of the inner ring; The hoops that intersect the corners are convex curved surfaces with a circular cross-sectional shape and both axial and radial dimensions of 1.0 mm or more, and are applied to the corners as the caulking part is processed The stress is regulated in the range of 40 to 300 MPa.

上記角部は、上記かしめ部により抑え付けられた鋼製の内輪の外周面と、この内輪の軸方向両端面のうちで上記かしめ部が設けられた側の端面とが交差する角部の総てを言う。例えば、図６（Ａ）に示す様に、端部に段差を持たない内輪３であれば、上記角部はイの１個所のみとなる。これに対して、同図（Ｂ）に示す様に、端部に段差を設けた内輪３ｂであれば、上記角部はロ、ハの２個所となる。何れにしても、角部の断面形状を、図７に示す様な円弧形とし、この円弧形部分の軸方向寸法Ｘ及び径方向寸法Ｙを、何れも１．０mm以上確保する。   The corner portion is the total of the corner portions where the outer peripheral surface of the steel inner ring held down by the caulking portion intersects the end surface on the side where the caulking portion is provided among the axial end surfaces of the inner ring. Say. For example, as shown in FIG. 6 (A), in the case of the inner ring 3 having no step at the end portion, the corner portion has only one point (a). On the other hand, as shown in FIG. 5B, in the case of the inner ring 3b having a step at the end, the corner portion has two locations, B and C. In any case, the cross-sectional shape of the corner portion is an arc shape as shown in FIG. 7, and the axial dimension X and the radial dimension Y of the arc-shaped portion are both 1.0 mm or more.

上述の様に構成すれば、更に上記内輪に遅れ破壊が発生しにくくできる。この理由に就いて、以下に説明する。
上記かしめ部を形成すべく、内径側部材の端部に形成した円筒部を塑性変形させる際に上記内輪には、径方向外方に向いた大きな力が加わり、その結果、この内輪の一部で上記かしめ部が設けられる側の端部に大きな引っ張り応力が、円周方向に作用する。そして、上記かしめ部を加工する為の荷重が除かれた後に於いても上記内輪の端部には、前述したフープ応力が残留する。 If comprised as mentioned above, it can be made hard to generate | occur | produce a delayed fracture further in the said inner ring | wheel. The reason will be described below.
When the cylindrical portion formed at the end portion of the inner diameter side member is plastically deformed to form the caulking portion, a large force is applied to the inner ring in the radially outward direction. Thus, a large tensile stress acts in the circumferential direction on the end portion on the side where the caulking portion is provided. Even after the load for machining the caulking portion is removed, the above-described hoop stress remains at the end of the inner ring.

この状態で、上記内輪を構成する鋼のうちで上記端部に水素が侵入すると、上記遅れ破壊が発生し易くなる。この遅れ破壊は、静的な荷重が加わった状態で、腐食等の影響により鋼中に水素が侵入した場合に生じる現象であり、上記フープ応力が上記静的荷重に相当する。このフープ応力は、上記かしめ部に対向する上記内輪の端部のうち、内径側で大きく、外径側程小さくなる。従って、上記フープ応力（静的荷重）の面からのみ考えれば、上記内輪の端部のうちの内径側部分から、上記遅れ破壊が発生し易くなるものと考えられる。   In this state, when hydrogen enters the end of the steel constituting the inner ring, the delayed fracture is likely to occur. This delayed fracture is a phenomenon that occurs when hydrogen enters the steel under the influence of corrosion or the like with a static load applied, and the hoop stress corresponds to the static load. The hoop stress is larger on the inner diameter side and smaller on the outer diameter side of the end portion of the inner ring facing the caulking portion. Therefore, considering only from the surface of the hoop stress (static load), the delayed fracture is likely to occur from the inner diameter side portion of the end portion of the inner ring.

但し、上記内輪の端部のうちの内径側部分は、上記かしめ部により覆われて水分が付着する事がなく、カバーやシールリングによるシール性が損なわれた場合（或は、コスト低減、重量軽減等の為にカバーを省略した場合）でも、水素侵入の原因となる腐食が発生しない。又、上記内径側部分には、上記かしめ部を密着させる為に、元々曲率半径の大きな凸曲面が存在する為、全体として大きなフープ応力が生じていても、この応力が緩和されて、部分的に集中する事がない。従って、上記内輪の端部のうちの内径側部分は、上記遅れ破壊の起点とはなりにくい。   However, the inner diameter side portion of the end portion of the inner ring is covered with the caulking portion so that moisture does not adhere to it, and the sealing performance by the cover or seal ring is impaired (or cost reduction, weight) Even when the cover is omitted for mitigation, etc., corrosion that causes hydrogen intrusion does not occur. Further, since the convex portion having a large curvature radius originally exists in the inner diameter side portion so that the caulking portion is in close contact, even if a large hoop stress is generated as a whole, this stress is alleviated and partially Don't concentrate on. Therefore, the inner diameter side portion of the end portion of the inner ring is unlikely to be the starting point of the delayed fracture.

これに対して、上記内輪の端部のうちの外径側部分で、この内輪の外周面と軸方向端面とが交差する角部の断面形状は、曲率半径が極小さい為、上記フープ応力が部分的に集中し易い。又、この角部は上記かしめ部により覆われる事がなく、上記カバーやシールリングによるシール性が損なわれた場合には、水素侵入の原因となる腐食が発生し易い。この為、上記角部は、遅れ破壊発生の起点となり易い。特に、前述の図５に示した構造の様に、内端面の外径側半部を軸方向に凹ませて内端部を段付形状とした内輪３ｂの場合、この内輪３ｂの内端部に存在する２個所の角部のうちの内径側の角部は、比較的大きなフープ応力が加わる事から、上記遅れ破壊の起点となり易い。又、何れの角部に関しても、他の部分に比べて熱容量が小さく、焼き入れ時の冷却速度が大きい為、マルテンサイト変態時に引っ張りの変態応力が残存し易く、この面からも、上記角部が遅れ破壊の起点になり易い原因の一つと考えられる。   On the other hand, in the outer diameter side portion of the end portion of the inner ring, the cross-sectional shape of the corner portion where the outer peripheral surface of the inner ring and the end surface in the axial direction intersect has a very small radius of curvature. Easy to concentrate partially. In addition, the corners are not covered by the caulking part, and when the sealing performance by the cover or the seal ring is impaired, corrosion that causes hydrogen intrusion is likely to occur. For this reason, the said corner | angular part tends to become a starting point of delayed fracture occurrence. In particular, as in the structure shown in FIG. 5 described above, in the case of the inner ring 3b in which the outer end side half of the inner end face is recessed in the axial direction and the inner end is stepped, the inner end of the inner ring 3b Of the two corners existing in the corner, the corner on the inner diameter side is subject to a relatively large hoop stress, and therefore tends to be the starting point of the delayed fracture. In addition, since any of the corners has a smaller heat capacity than the other parts and a high cooling rate at the time of quenching, tensile transformation stress tends to remain at the time of martensitic transformation. This is considered to be one of the causes of delayed fracture.

この様にして発生する遅れ破壊に対して、請求項３に記載した発明の場合には、上記内輪の外周面と軸方向端面とが交差する角部を、断面形状が円弧形で、軸方向寸法及び径方向寸法が何れも１．０mm以上である凸曲面としている為、上記かしめ部の加工に基づくフープ応力、及び、上記変態応力が、上記角部に引っ張り応力として集中する事を緩和できる。この結果、上記内輪全体としての、遅れ破壊に対する強度が高くなる。又、上記かしめ部の加工に伴って上記角部に加わるフープ応力を４０〜３００ＭＰａの範囲に規制しているので、内径側部材に対する上記内輪の支持強度を確保しつつ、この内輪に遅れ破壊が発生する事を有効に防止できる。上記フープ応力を４０ＭＰａ未満に抑えようとすると、上記かしめ部による上記内輪の支持強度を十分に確保する事が難しくなる。反対に、上記フープ応力が３００ＭＰａを越えた場合には、上記角部を上記凸曲面としても、それだけでは、遅れ破壊の発生防止を十分に図る事が難しくなる。   In the case of the invention described in claim 3, with respect to the delayed fracture that occurs in this way, the corner where the outer peripheral surface of the inner ring intersects the axial end surface has an arc shape in cross section and a shaft Since both the directional dimension and the radial dimension are convex curved surfaces of 1.0 mm or more, the hoop stress based on the processing of the caulking portion and the transformation stress are alleviated from being concentrated as tensile stress on the corner portion. it can. As a result, the strength against delayed fracture as the entire inner ring increases. In addition, since the hoop stress applied to the corner portion in connection with the caulking portion is regulated within the range of 40 to 300 MPa, the inner ring is subject to delayed fracture while ensuring the supporting strength of the inner ring with respect to the inner diameter side member. It is possible to effectively prevent the occurrence. If the hoop stress is to be suppressed to less than 40 MPa, it is difficult to sufficiently secure the support strength of the inner ring by the caulking portion. On the other hand, when the hoop stress exceeds 300 MPa, it is difficult to sufficiently prevent the occurrence of delayed fracture even if the corner portion is the convex curved surface.

又、請求項４に記載した発明を実施する場合に好ましくは、請求項５に記載した様に、内輪の外周面と、この内輪の軸方向両端面のうちでかしめ部が設けられた側の端面とが交差する角部を、この内輪に焼き入れ、焼き戻しを含む熱処理を施した後に行なわれる、研削加工、旋削加工（ターニング加工）、バニシング加工のうちから選択される何れかの加工により、断面形状が円弧形で軸方向寸法及び径方向寸法が何れも１．０mm以上であって、表面から５０〜１００μｍの深さ部分の残留圧縮応力が２００ＭＰａ以上（好ましくは５００ＭＰａ）である凸曲面とする。且つ、上記かしめ部の加工に伴って上記角部に加わるフープ応力を、４０〜３５０ＭＰａの範囲に規制する。   Further, when the invention described in claim 4 is carried out, preferably, as described in claim 5, the outer ring surface of the inner ring and the axially opposite end surfaces of the inner ring on the side where the caulking portion is provided. The corner portion intersecting with the end face is quenched into this inner ring and subjected to a heat treatment including tempering, by any processing selected from grinding, turning (turning), and burnishing A convex shape whose cross-sectional shape is an arc shape, the axial dimension and the radial dimension are both 1.0 mm or more, and the residual compressive stress at a depth of 50 to 100 μm from the surface is 200 MPa or more (preferably 500 MPa). Let it be a curved surface. And the hoop stress added to the said corner | angular part with the process of the said crimping part is controlled in the range of 40-350 MPa.

この様な請求項５に記載した発明の場合には、上記フープ応力の上限値を３５０ＭＰａまで高くする事ができる。即ち、上記部分の残留圧縮応力を確保すれば、上記フープ応力が多少大きくても、このフープ応力に基づく遅れ破壊の発生を抑えられる。言い換えれば、上記部分に圧縮応力を残留させる事で、同じフープ応力が存在する場合に、上記遅れ破壊の発生防止効果がより向上する。   In the case of the invention described in claim 5, the upper limit value of the hoop stress can be increased to 350 MPa. That is, if the residual compressive stress in the above portion is ensured, the occurrence of delayed fracture based on the hoop stress can be suppressed even if the hoop stress is somewhat large. In other words, by causing the compressive stress to remain in the portion, the effect of preventing the delayed fracture is further improved when the same hoop stress is present.

又、請求項３、５に記載した発明を実施する場合に好ましくは、請求項６に記載した様に、凸曲面の軸方向寸法Ｘを１．５mm以上とする。
この様に構成すれば、フープ応力に基づく角部への応力集中をより一層緩和して、この角部から遅れ破壊が発生する事を、より効果的に防止できる。
更に、請求項３、５、６に記載した発明を実施する場合に好ましくは、請求項７に記載した様に、上記角部の凸曲面の表面粗さを０．２μｍＲａ以下とする。
この様にすれば、上記角部の表面の一部に応力が集中する事を防止して、より優れた、上記遅れ破壊の防止効果を得られる。 Further, when carrying out the invention described in claims 3 and 5, preferably, as described in claim 6, the axial dimension X of the convex curved surface is set to 1.5 mm or more.
If comprised in this way, the stress concentration to the corner | angular part based on a hoop stress can be eased further, and it can prevent more effectively that delayed fracture generate | occur | produces from this corner | angular part.
Furthermore, when carrying out the invention described in claims 3, 5 and 6, preferably, as described in claim 7, the surface roughness of the convex curved surface of the corner is set to 0.2 μmRa or less.
In this way, it is possible to prevent stress from being concentrated on a part of the surface of the corner portion, and to obtain a more excellent delayed fracture prevention effect.

本発明の効果を確認する為に行なった第一の実験に就いて説明する。
この実験では、前述の図１に示した様な従動輪用車輪支持用転がり軸受ユニット（４９ＢＷＫＨ１７、転動体直径＝１／２インチ、ピッチ円直径＝４９mm、転動体の作用点間距離＝６６．１mm）を構成する内輪３の内端面外周縁（角部）の断面形状を、下記の表１に示す様に種々異ならせると共に、この内輪３の内端面を抑え付ける為のかしめ部９を加工する際の荷重を種々変える事により、この内輪３の角部に残留するフープ応力を、表１に示す様に種々異ならせた。この内輪２は、高炭素クロム軸受鋼２種（ＳＵＪ２）製とし、８２０〜８４０℃に加熱保持後、焼き入れ、焼き戻しを行ない、硬度をＨＲＣ５８〜６２としたものを用いた。尚、実施例１５〜２８に示した１４種類の試料は、実施例１に示した試料に、焼き入れ、焼き戻し後にターニング加工を施す事により、角部の断面を所望の形状に加工すると共に、表面から５０〜１００μｍの深さ部分に、表１に示す様な圧縮応力を残留させたものである。 A first experiment conducted to confirm the effect of the present invention will be described.
In this experiment, a wheel bearing rolling bearing unit for a driven wheel as shown in FIG. 1 (49BWK17, rolling element diameter = 1/2 inch, pitch circle diameter = 49 mm, distance between operating points of rolling elements = 66. As shown in Table 1 below, the cross-sectional shape of the inner edge 3 outer peripheral edge (corner) of the inner ring 3 constituting 1 mm) is varied, and the caulking portion 9 for suppressing the inner end face of the inner ring 3 is processed. As shown in Table 1, the hoop stress remaining in the corner portion of the inner ring 3 was varied by changing the load at the time. This inner ring 2 was made of high-carbon chromium bearing steel type 2 (SUJ2), heated and held at 820 to 840 ° C., quenched and tempered, and used with a hardness of HRC 58 to 62. The 14 types of samples shown in Examples 15 to 28 were processed into a desired shape by cross-sectioning the corners by subjecting the sample shown in Example 1 to hardening after tempering and tempering. The compressive stress as shown in Table 1 is left in the depth portion of 50 to 100 μm from the surface.

Figure 2005098475
Figure 2005098475

尚、本発明の対象となる車輪支持用転がり軸受ユニットには、通常、カバー２５及びシールリング２６が装着され、上記内輪３の設置部分を含めて、内部へ雨水や泥水の侵入を防止する構成となっている。又、転動体５、５設置部分にはグリースが充填され、このグリースの一部が上記内輪３の表面にも付着して、この内輪３が水に濡れにくい状態となっている。但し、実験では、上記カバー２５及びシールリング２６を除き、上記グリースも充填せずに、上記内輪３が濡れ易い状態とした。そして、上記表１に示した、本発明の技術的範囲に属する２８種類の試料（実施例１〜２８）と、本発明の技術的範囲からは外れる９種類の試料（比較例１〜９）との、合計３７種類の試料を、水道水に浸漬した。この結果、これら３７種類の試料の総てに就いて、上記内輪３に遅れ破壊は発生しなかった。   In addition, the wheel support rolling bearing unit that is the subject of the present invention is usually provided with a cover 25 and a seal ring 26, and prevents the intrusion of rainwater and muddy water into the interior including the installation portion of the inner ring 3. It has become. Further, the rolling elements 5 and 5 are installed with grease, and a part of the grease adheres to the surface of the inner ring 3 so that the inner ring 3 is hardly wetted by water. However, in the experiment, except for the cover 25 and the seal ring 26, the inner ring 3 was easily wetted without filling the grease. And 28 types of samples (Examples 1 to 28) belonging to the technical scope of the present invention shown in Table 1 above, and 9 types of samples (Comparative Examples 1 to 9) outside the technical scope of the present invention. A total of 37 types of samples were immersed in tap water. As a result, delayed fracture did not occur in the inner ring 3 for all of these 37 types of samples.

次いで、上記各試料（水道水に浸漬した試料そのもの）に、更に以下の条件で同様の浸漬試験を施した。
試験条件
試験溶液 ： ２０％チオシアン酸アンモニウム水溶液（ＮＨ4 ＣＮＳ）
温度 ： ５０℃±１℃
試験時間 ： ２００時間
この試験条件は、プレストレストコンクリートに用いられる鋼線、鋼棒（ＰＣ鋼と称する）の水素による遅れ破壊を評価する標準試験と同一条件であって、車輪支持用転がり軸受ユニットにとって実際の環境を再現するものではない（実際の使用環境よりも厳しい）。但し、水素脆性に基づく遅れ破壊に関する耐性を評価できる有効な手法である。 Next, the same immersion test was further performed on each of the above samples (the sample itself immersed in tap water) under the following conditions.
Test conditions Test solution: 20% ammonium thiocyanate aqueous solution (NH 4 CNS)
Temperature: 50 ℃ ± 1 ℃
Test time: 200 hours This test condition is the same as the standard test for evaluating delayed fracture due to hydrogen in steel wires and steel bars (PC steel) used for prestressed concrete, and for wheel bearing rolling bearing units. It does not reproduce the actual environment (severe than the actual usage environment). However, this is an effective method for evaluating the resistance to delayed fracture based on hydrogen embrittlement.

この様な条件で行なった耐久試験の結果を、前記表１及び図８、９に示した。これら図８、９は、前記角部の断面形状と、フープ応力との関係を示すもので、図８は実施例１〜１４（角部の表層部に残留圧縮応力が存在しないもの）及び比較例１〜９に関するものを、図９は実施例１５〜２８（角部の表層部に残留圧縮応力が存在するもの）及び比較例１〜９に関するものを、それぞれ示している。又、図８、９で、「●」印は、２００時間経過時にも内輪３に遅れ破壊は発生しなかった事を、「○」印は、２００時間経過する以前に内輪３に遅れ破壊が発生した事を、それぞれ表している。又、図８、９の縦軸はフープ応力の大きさを、横軸は角部の断面形状の円弧形部分の軸方向寸法Ｘと径方向寸法Ｙとの平均値｛（Ｘ＋Ｙ）／２｝を、それぞれ表している。
前述の様な条件で行なった実験の結果を表した、前記表１及び図８、９から明らかな通り、本発明によれば、ハブ或は軸部材等の内径側部材に外嵌した内輪を、この内径側部材に形成したかしめ部により抑え付ける構造で、この内輪に遅れ破壊が発生しにくい構造を実現できる。 The results of the durability test conducted under such conditions are shown in Table 1 and FIGS. 8 and 9 show the relationship between the cross-sectional shape of the corner portion and the hoop stress. FIG. 8 shows Examples 1 to 14 (the surface portion of the corner portion has no residual compressive stress) and comparison. FIG. 9 shows examples relating to Examples 1 to 9, and examples relating to Examples 15 to 28 (where the residual compressive stress is present in the surface layer portion of the corners) and Comparative Examples 1 to 9, respectively. In FIGS. 8 and 9, “●” indicates that no delayed fracture occurred in the inner ring 3 even after 200 hours had elapsed, and “◯” indicates that the inner ring 3 had delayed fracture before 200 hours had elapsed. Each occurrence is represented. 8 and 9, the vertical axis indicates the magnitude of the hoop stress, and the horizontal axis indicates the average value {(X + Y) / 2 between the axial dimension X and the radial dimension Y of the arc-shaped portion of the corner cross-sectional shape. }, Respectively.
As is apparent from Table 1 and FIGS. 8 and 9 showing the results of the experiment conducted under the above-described conditions, according to the present invention, the inner ring externally fitted to the inner diameter side member such as a hub or a shaft member is provided. A structure in which the inner ring is restrained by a caulking portion and a structure in which delayed fracture is unlikely to occur in the inner ring can be realized.

本発明の効果を確認する為に行なった第二の実験、並びに、遅れ破壊防止に関する効果が優れた車輪支持用転がり軸受ユニットの具体的製造方法に就いて説明する。この第二の実験の場合も、上述した第一の実験の場合と同様に、図１に示した車輪支持用転がり軸受ユニットからカバー２５及びシールリング２６を除き、グリースも充填せずに、内輪３が濡れ易い状態のものを使用して、腐食環境下の耐久試験を行なった。本実施例の場合には、車輪支持用転がり軸受ユニットを、関東ローム粉を混ぜた塩水に浸した。この様な実験の結果、上記内輪３の表面に、４００〜８００ＭＰａの円周方向の引っ張り応力（フープ応力）が残留していると、この内輪３に亀裂が生じる場合がある事が分かった。尚、この内輪３に亀裂が生じるに至る、残留引っ張り応力の値は、最小４００ＭＰａから最大８００ＭＰａと、車輪支持用転がり軸受ユニットの名番（大きさ）によって、値のバラツキがあった。但し、残留引っ張り応力が４００ＭＰａ以下であれば、上記の様な腐食環境下でも、上記内輪３に亀裂が発生し、更に進展する事はなかった。   A second experiment conducted for confirming the effect of the present invention and a specific method for manufacturing a wheel bearing rolling bearing unit excellent in the effect of preventing delayed fracture will be described. In the case of the second experiment, as in the case of the first experiment described above, the cover 25 and the seal ring 26 are removed from the wheel support rolling bearing unit shown in FIG. A durability test in a corrosive environment was performed using the sample 3 that was easily wetted. In the case of this example, the wheel-supporting rolling bearing unit was immersed in salt water mixed with Kanto loam powder. As a result of such an experiment, it has been found that if a tensile stress (hoop stress) in the circumferential direction of 400 to 800 MPa remains on the surface of the inner ring 3, the inner ring 3 may be cracked. The value of the residual tensile stress at which the inner ring 3 is cracked varies from 400 MPa to 800 MPa, depending on the name (size) of the wheel bearing rolling bearing unit. However, if the residual tensile stress was 400 MPa or less, the inner ring 3 was cracked and did not further progress even under the corrosive environment as described above.

この様な腐食環境下の試験を行なった結果から、安全率を見込んで、内輪表面に残留する円周方向の引っ張り応力（フープ応力）を３００ＭＰａ以下（請求項１に記載した発明の条件）に抑えれば、車輪用軸受ユニットの使用状態として一般的に考えられる環境下であれば、上記内輪に遅れ破壊が発生する事を十分に防止できる事が分かる。尚、本発明が、残留応力のうちの円周方向の成分に着目してなした理由は、かしめ部９の加工に伴って上記内輪３に、円周方向の引っ張り応力（フープ応力）が加わり、この引っ張り応力が亀裂等の破壊に結び付く為である。尚、上記実験に使用した上記内輪３は、単体の状態（この内輪３をハブ２に圧入外嵌する以前の状態）で、初期応力が全く残留していないものを使用した。   From the result of the test in such a corrosive environment, in consideration of the safety factor, the circumferential tensile stress (hoop stress) remaining on the inner ring surface is set to 300 MPa or less (condition of the invention described in claim 1). If it suppresses, it will be understood that delayed fracture can be sufficiently prevented from occurring in the inner ring under an environment generally considered as a use state of the wheel bearing unit. The reason why the present invention pays attention to the circumferential component of the residual stress is that a circumferential tensile stress (hoop stress) is applied to the inner ring 3 as the caulking portion 9 is processed. This is because this tensile stress leads to breakage such as cracks. The inner ring 3 used in the experiment was a single body (a state before the inner ring 3 was press-fitted and fitted into the hub 2) and no initial stress remained.

この様な内輪３を上記ハブ２に外嵌し、更にかしめ部９によりその内端面を抑え付けた状態に就いて、コンピュータシミュレーションすると、上記かしめ部９側の端部に、円周方向の引っ張り応力（フープ応力）が生じる事が分かる。又、この円周方向の残留引っ張り応力は、上記内輪３の端面部分で最大になる事も分かる。この様に内輪３の表面に残留する円周方向の応力の大きさには、この内輪３に関して順次施される、熱処理工程、研削工程、かしめ工程の３種類の工程が大きく影響する。これら各工程の間で施される他の工程は、上記応力に殆ど影響を及ぼさない。又、上記３種類の工程のうちで、かしめ工程は、上記内輪３の端部に、破壊に関して悪影響を及ぼす円周方向の引っ張り応力を生じさせるのみであり、破壊防止に繋がる圧縮応力を生じさせる事はない。これに対して、残りの２種類の工程、即ち、熱処理工程と研削工程とに関しては、加工条件を適切に選定する事で、上記内輪３の表面に円周方向の圧縮応力を残留させる事ができる。   When the inner ring 3 is externally fitted to the hub 2 and the inner end surface thereof is further suppressed by the caulking portion 9, a computer simulation shows that the end portion on the caulking portion 9 side is pulled in the circumferential direction. It can be seen that stress (hoop stress) occurs. It can also be seen that the residual tensile stress in the circumferential direction is maximized at the end face portion of the inner ring 3. In this way, the magnitude of the circumferential stress remaining on the surface of the inner ring 3 is greatly affected by three types of processes, which are sequentially performed with respect to the inner ring 3, including a heat treatment process, a grinding process, and a caulking process. The other steps performed between these steps hardly affect the stress. Of the above-mentioned three types of processes, the caulking process only generates a tensile stress in the circumferential direction that has an adverse effect on the destruction at the end of the inner ring 3, and a compressive stress that leads to the prevention of the destruction. There is nothing. On the other hand, regarding the remaining two types of processes, that is, the heat treatment process and the grinding process, it is possible to leave a compressive stress in the circumferential direction on the surface of the inner ring 3 by appropriately selecting the processing conditions. it can.

この様に、最後に行なうかしめ工程では、上記内輪３の表面に円周方向の引っ張り応力が生じる傾向になる。従って、このかしめ工程を終了した後の状態で、上記内輪３の表面に残留する円周方向の引っ張り応力（フープ応力）を３００ＭＰａ以下に抑え、好ましくは円周方向に圧縮応力を残留させる為には、上記熱処理工程と上記研削工程とのうちの少なくとも一方の工程で、上記内輪３単体の端面、特に、この内輪３単体での面取り部に、円周方向の大きな圧縮応力を残留させる必要がある。そして、上記かしめ工程で引っ張り側に作用する応力以上に、上記熱処理工程と上記研削工程とで、上記内輪３の単体に圧縮応力を残留させれば、上記かしめ工程の後、この内輪３に大きな圧縮応力を残留させる事が可能になる。   In this way, in the last caulking step, circumferential tensile stress tends to occur on the surface of the inner ring 3. Accordingly, in order to suppress the circumferential tensile stress (hoop stress) remaining on the surface of the inner ring 3 to 300 MPa or less and preferably leave the compressive stress in the circumferential direction after the caulking process is completed. In at least one of the heat treatment step and the grinding step, it is necessary to leave a large circumferential compressive stress on the end surface of the inner ring 3 alone, particularly on the chamfered portion of the inner ring 3 alone. is there. Then, if compressive stress remains in the inner ring 3 alone in the heat treatment step and the grinding step, more than the stress acting on the pulling side in the caulking step, the inner ring 3 will be larger after the caulking step. It becomes possible to leave compressive stress.

そこで、車輪支持用転がり軸受ユニットの完成後、上記内輪３に大きな円周方向の引っ張り応力（フープ応力）が残留しない様にする為に好ましい、熱処理工程、研削工程、かしめ工程の条件の具体例に就いて説明する。尚、上記内輪３の残留応力の測定は、Ｘ線により行なった。Ｘ線の測定面積は、２mm×２mmの正方形の範囲内とし、実測した応力値は、この範囲内の平均値とした。又、深さ方向の測定範囲は約１０μｍとした。   Therefore, specific examples of conditions of the heat treatment process, the grinding process, and the caulking process that are preferable in order to prevent a large circumferential tensile stress (hoop stress) from remaining in the inner ring 3 after the wheel bearing rolling bearing unit is completed. I will explain. The residual stress of the inner ring 3 was measured by X-ray. The X-ray measurement area was within a square area of 2 mm × 2 mm, and the actually measured stress value was an average value within this range. The measurement range in the depth direction was about 10 μm.

［熱処理工程］
内輪３は、高炭素クロム軸受鋼２種（ＪＩＳ ＳＵＪ２）に準ずるもので、Ｏ．９〜１．１０重量％のＣと、ｌ．２０〜１．６５重量％のＣｒとを含むものとした。熱処理後に、この様な内輪３に圧縮応力を残留させる為に、この内輪３を、８２０〜８６０℃で焼き入れした後、油により急冷した。次いで、１７０〜１８０℃で焼き戻してから空冷した。尚、上記内輪３単体の搬送は、ベルトコンベアで行なった。この様な条件で行なった熱処理工程の後、上記内輪３に、次の表２に示す様な、円周方向に関する応力が残留した。この応力は、引っ張り応力を正の値としており、この応力が「−」であるとは、当該応力が圧縮応力である事を表している。 [Heat treatment process]
The inner ring 3 conforms to high carbon chromium bearing steel class 2 (JIS SUJ2). 9 to 1.10% by weight of C, l. It contained 20 to 1.65 wt% Cr. After the heat treatment, the inner ring 3 was quenched at 820 to 860 ° C. and then quenched with oil in order to leave compressive stress in the inner ring 3. Subsequently, after tempering at 170-180 degreeC, it air-cooled. In addition, the said inner ring | wheel 3 single-piece | unit was performed with the belt conveyor. After the heat treatment process performed under such conditions, stress in the circumferential direction as shown in Table 2 below remained in the inner ring 3. This stress has a positive tensile stress, and the stress being “−” indicates that the stress is a compressive stress.

Figure 2005098475
Figure 2005098475

この様な表２のうち、左欄は、上記内輪３単体の端面に発生する円周方向の残留応力を表している。上述の様な熱処理の結果、この端面に、−２００〜−４００ＭＰａと、大きな圧縮応力が残留している事が分かる。尚、上記表２の右欄は、上記内輪３単体の端部外周縁部の面取り部分に発生した、円周方向の残留応力である。この面取り部分に関しては、円周方向の引っ張り応力が残留したが、その値は、＋１００ＭＰａ以下の小さな値であった。この様に、内輪３の端面側でも、場所により残留応力が圧縮応力になったり、逆に引っ張り応力になったりする理由は、次の通りである。   In Table 2, the left column represents the residual stress in the circumferential direction generated on the end surface of the inner ring 3 alone. As a result of the heat treatment as described above, it can be seen that a large compressive stress of -200 to -400 MPa remains on this end face. The right column of Table 2 shows the residual stress in the circumferential direction generated at the chamfered portion of the outer peripheral edge of the inner ring 3 alone. Regarding this chamfered portion, a tensile stress in the circumferential direction remained, but the value was a small value of +100 MPa or less. As described above, the reason why the residual stress becomes a compressive stress or a tensile stress on the end face side of the inner ring 3 depending on the location is as follows.

上記内輪３の端部外周縁部の面取り部分は曲率半径が小さい為、当該部分の容積に比べて表面積が相対的に広い。上記熱処理の際には、上記内輪３の表面が油に接触する事で冷却されるが、その表面が相対的に広いと冷却速度が速くなる。これに対して、上記内輪３の端面は、曲率半径が上記面取り部の曲率半径に比べ遥かに非常に大きい（実質的に無限大である）為、当該部分の容積に比べて表面積が相対的に狭い。従って、上記熱処理の際には、上記内輪３の端面の径方向中間部は、上記面取り部分に比べ、冷却速度が遅くなる。そして、冷却速度、延ては熱収縮速度が速いこの面取り部分には引っ張り応力が残留し、熱収縮速度が遅い端面の径方向中間部には圧縮応力が残留する。上記面取り部に引っ張り応力が残留した場合でも、その値が小さければあまり問題とはならない。但し、熱処理工程後に、上記内輪３単体の面取り部分に、２００ＭＰａ以上の引っ張り応力が残留する場合には、前述の実施例１の様に、面取り部分の径方向及び軸方向の寸法を大きくする等して、この面取り部分の冷却速度を遅くする。   Since the chamfered portion of the outer peripheral edge of the inner ring 3 has a small radius of curvature, the surface area is relatively large compared to the volume of the portion. During the heat treatment, the surface of the inner ring 3 is cooled by coming into contact with oil. However, if the surface is relatively wide, the cooling rate is increased. On the other hand, the end surface of the inner ring 3 has a radius of curvature that is much larger (substantially infinite) than the radius of curvature of the chamfered portion, so that the surface area is relative to the volume of the portion. Narrow. Therefore, at the time of the heat treatment, the cooling rate of the intermediate portion in the radial direction of the end surface of the inner ring 3 is slower than that of the chamfered portion. Then, tensile stress remains in the chamfered portion where the cooling rate, and hence the thermal shrinkage rate is high, and compressive stress remains in the radial intermediate portion of the end surface where the thermal shrinkage rate is low. Even when a tensile stress remains in the chamfered portion, if the value is small, it does not matter much. However, when a tensile stress of 200 MPa or more remains in the chamfered portion of the inner ring 3 alone after the heat treatment process, the radial and axial dimensions of the chamfered portion are increased as in the first embodiment. Thus, the cooling rate of the chamfered portion is reduced.

［研削工程］
上記内輪３単体への研削加工は、図１０に示す様に、上下２個の砥石２７ａ、２７ｂを備えた両頭研削盤により行ない、上記内輪３の軸方向両端面を研削する。この両頭研削盤を表した図１０の上下方向は実際の上下方向と一致しており、上記両砥石２７ａ、２７ｂは、互いに同心で鉛直方向に配置された回転軸を中心として回転する。そして、図１１に示す様なロータリキャリア２８により、上記両砥石２７ａ、２７ｂ同士の間に、上記内輪３の搬入、搬出を行なう。この内輪３は、図１０に示す様に、軸方向両端面のうちの面積の広い側の端面を下側の砥石２７ａで研削し、面積の狭い側の端面を上側の砥石２７ｂで研削する。従って、この上側の砥石２７ｂによる削り代は、下側の砥石２７ａの削り代に比べて少なくなる。この様に、削り代が少ない上記上側の砥石２７ｂの回転速度は、削り代が多い下側の砥石２７ａの回転速度よりも遅くする。例えば、上側の砥石２７ｂの回転速度は、１００〜１２００ｍｉｎ-1、更に好ましくは５００〜８００ｍｉｎ-1とし、下側の砥石２７ａの回転速度は、８００〜１２００ｍｉｎ-1、更に好ましくは８００〜１０００ｍｉｎ-1とする。研削加工の間中、上記両砥石２７ａ、２７ｂの回転速度は一定とするが、必要に応じてこれら両砥石２７ａ、２７ｂの回転速度は可変にする。そして、研削加工を施した上記内輪３の表面性状を観察しながら、適切な表面性状を得られる様に、適宜調節する。上記両砥石２７ａ、２７ｂの回転速度は、上記内輪３が組み込まれる車輪支持用転がり軸受ユニットの名番により変える場合もある。 [Grinding process]
As shown in FIG. 10, the grinding of the inner ring 3 alone is performed by a double-headed grinding machine having two upper and lower grindstones 27a and 27b, and both axial end surfaces of the inner ring 3 are ground. The vertical direction of FIG. 10 showing this double-head grinding machine coincides with the actual vertical direction, and the both grinding wheels 27a and 27b rotate around the rotation shafts that are concentrically arranged in the vertical direction. Then, the inner ring 3 is carried in and out between the grinding wheels 27a and 27b by a rotary carrier 28 as shown in FIG. As shown in FIG. 10, the inner ring 3 is such that the end face on the side with the larger area of both end faces in the axial direction is ground with the lower grindstone 27a, and the end face with the smaller area is ground with the upper grindstone 27b. Therefore, the cutting allowance by the upper grindstone 27b is smaller than the cutting allowance of the lower grindstone 27a. In this way, the rotational speed of the upper grinding wheel 27b having a small machining allowance is made slower than the rotational speed of the lower grinding wheel 27a having a large machining allowance. For example, the rotational speed of the upper grinding wheel 27b is, 100～1200Min -1, more preferably a 500～800Min -1, rotational speed of the lower grinding wheel 27a is, 800～1200Min -1, more preferably 800～1000Min - Set to 1 . During the grinding process, the rotational speeds of both the grindstones 27a and 27b are constant, but the rotational speeds of both the grindstones 27a and 27b are variable as necessary. Then, while observing the surface texture of the inner ring 3 that has been subjected to the grinding process, the inner ring 3 is appropriately adjusted so as to obtain an appropriate surface texture. The rotational speeds of the two grinding wheels 27a and 27b may be changed depending on the name of the wheel bearing rolling bearing unit in which the inner ring 3 is incorporated.

上記両砥石２７ａ、２７ｂが、図１０、１１の上側から見て時計方向に回転すると仮定した場合、上記ロータリーキャリア２８は反時計回りに回転する。そして、このロータリキャリア２８のポケット２９、２９に保持された上記内輪３は、上記両砥石２７ａ、２７ｂの外径側から入ってこれら両砥石２７ａ、２７ｂの上下両面同士の間を通過し、外径側に出る。この場合、上記ロータリキャリア２８による、上記内輪３の搬送速度は、５〜２５mm／sec である。又、このロータリキャリア２８により搬送される内輪３が、上記両砥石２７ａ、２７ｂの上下両面同士の間に円滑に入り込む様に、上側の砥石２７ｂを下側の砥石２７ａに対し僅かに傾斜させて、入口部分でのこれら両砥石２７ａ、２７ｂ同士の間隔を、出口部分での間隔に比べて１０〜２０μｍ広くしている。又、上記内輪３は上記各ポケット２９、２９内に、それぞれの中心軸回りの回転自在に保持される。従って、研削加工中に上記内輪３は、その両端面と上記両砥石２７ａ、２７ｂとの摩擦により回転する場合がある。そして、この両端面に生じる研削目は、一方向に揃ったり、ハッチング状にになったりと、様々な模様になる。   When it is assumed that both the grindstones 27a and 27b rotate clockwise as viewed from the upper side of FIGS. 10 and 11, the rotary carrier 28 rotates counterclockwise. And the said inner ring | wheel 3 hold | maintained at the pockets 29 and 29 of this rotary carrier 28 enters from the outer diameter side of both said grindstones 27a and 27b, passes between both upper and lower surfaces of these both grindstones 27a and 27b, and is outside. Go to the radial side. In this case, the conveying speed of the inner ring 3 by the rotary carrier 28 is 5 to 25 mm / sec. Further, the upper grindstone 27b is slightly inclined with respect to the lower grindstone 27a so that the inner ring 3 conveyed by the rotary carrier 28 smoothly enters between the upper and lower surfaces of both the grindstones 27a, 27b. The distance between the two grindstones 27a and 27b at the entrance is wider by 10 to 20 μm than the distance at the exit. The inner ring 3 is held in the pockets 29, 29 so as to be rotatable about the respective central axes. Accordingly, during the grinding process, the inner ring 3 may rotate due to friction between both end faces thereof and the two grinding wheels 27a and 27b. The grinding marks generated on both end faces have various patterns such as being aligned in one direction or being hatched.

上記両砥石２７ａ、２７ｂの回転方向は、通常は同じ方向である。但し、上記内輪３の両端面である研削面に、だれ、くすみ等が生じた場合には、下側の砥石２７ａを、回転速度を一定としたまま、逆方向に回転（逆回転）させる。この下側の砥石２７ａを逆回転させる事で、研削性が向上し、良好な研削面を得られる。この下側の砥石２７ａの回転方向を変えても、研削面のだれやくすみを改善できない場合は、上記両砥石２７ａ、２７ｂにドレッシングを施す。   The rotational directions of the two grinding wheels 27a and 27b are usually the same direction. However, when drooling or dullness occurs on the ground surface, which is the both end surfaces of the inner ring 3, the lower grindstone 27a is rotated in the reverse direction (reverse rotation) while keeping the rotation speed constant. By rotating the lower grindstone 27a in reverse, the grindability is improved and a good ground surface can be obtained. If it is not possible to improve the sagging and dullness of the grinding surface even if the rotation direction of the lower grinding wheel 27a is changed, dressing is applied to both the grinding wheels 27a and 27b.

尚、上記両砥石２７ａ、２７ｂの仕様としては、次の値が適切である。
「上側の砥石２７ｂ」
粒度 ： ７０〜９０
結合度 ： Ｃ、Ｄ、Ｅ（下側の砥石２７ａに対し２〜７段階下げる場合がある）
組織 ： １１〜１３（通常よりも軟らかくする）
結合剤 ： レジノイド
「下側の砥石２７ａ」
粒度 ： ９０〜１２０
結合度 ： Ｉ、Ｊ、Ｋ、Ｌ
組織 ： １１〜１３（通常よりも軟らかくする）
結合剤 ： レジノイド The following values are appropriate for the specifications of the two grinding wheels 27a and 27b.
"Upper whetstone 27b"
Particle size: 70-90
Bonding degree: C, D, E (may be lowered by 2 to 7 steps with respect to the lower grindstone 27a)
Tissue: 11-13 (soften than usual)
Binder: Resinoid "Lower grinding wheel 27a"
Particle size: 90-120
Degree of coupling: I, J, K, L
Tissue: 11-13 (soften than usual)
Binder: Resinoid

上述の様な条件で、上記内輪３の両端面に研削加工を施せば、砥粒の切削作用や熱の作用が小さく、砥粒のバニッシュ作用が大きくなる。そして、上記内輪３単体の端面、この内輪３単体の面取り部分に、次の表３に示す様に、円周方向に関して大きな圧縮応力を残留させる事ができる。   If grinding is performed on both end faces of the inner ring 3 under the conditions as described above, the abrasive cutting action and heat action are small, and the abrasive grain burnishing action is increased. Further, as shown in the following Table 3, a large compressive stress in the circumferential direction can be left on the end face of the inner ring 3 alone and the chamfered portion of the inner ring 3 alone.

Figure 2005098475
Figure 2005098475

即ち、この表３の左欄に示す様に、上記内輪３単体の端面に、円周方向に関して、−６００ＭＰａ以上の、大きな圧縮応力を残留させる事ができた。更に、前述した熱処理工程を終了した段階で、円周方向に関する応力が若干の引っ張り応力であった、上記内輪３単体の面取り部分も、上記表３の右欄に示す様に、−２００ＭＰａ以上の圧縮応力が残留する状態となった。   That is, as shown in the left column of Table 3, a large compressive stress of −600 MPa or more could remain on the end surface of the inner ring 3 alone in the circumferential direction. Furthermore, the chamfered portion of the inner ring 3 alone, in which the stress in the circumferential direction was a slight tensile stress at the stage where the heat treatment step described above was completed, was also −200 MPa or more as shown in the right column of Table 3 above. Compressive stress remained.

［かしめ工程］
車輪支持用転がり軸受ユニットの端部に形成した円筒部１０を径方向外方に塑性変形させてかしめ部９とするかしめ加工は、ローリングプレス機（揺動プレス機）により行なう。揺動角度は１〜１０度の範囲内から適宜選択するが、特に２〜５度の範囲が好ましい。揺動回転数は１００〜１５００ min-1の範囲内で適宜選択するが、上記車輪支持用転がり軸受ユニットの名番によって変える。多くの場合、２００〜１０００ min-1の範囲内で設定する。又、上記揺動回転数は、かしめ品質を一定にする為、かしめ加工の進行に伴って変化させる事もできる。 [Caulking process]
The caulking process in which the cylindrical portion 10 formed at the end of the wheel bearing rolling bearing unit is plastically deformed radially outward to form the caulking portion 9 is performed by a rolling press machine (oscillating press machine). The swing angle is appropriately selected from the range of 1 to 10 degrees, and the range of 2 to 5 degrees is particularly preferable. The swinging rotational speed is appropriately selected within the range of 100 to 1500 min −1 , but varies depending on the wheel bearing rolling bearing unit name. In many cases, it is set within a range of 200 to 1000 min −1 . In addition, the rotational speed of rotation can be changed as the caulking process proceeds in order to keep the caulking quality constant.

何れにしても、上記かしめ工程では、上記円筒部１０を上記かしめ部９に加工するのに伴って、加工部が径方向外方に塑性変形する。この為、この加工部の周囲に外嵌された上記内輪３が、径方向に押し広げられる傾向になる。この結果、上記かしめ加工の進行に伴ってこの内輪３に、円周方向の引っ張り応力が加わる。前記表２、３に示した様に、熱処理工程及び研削工程により、上記内輪３の単体には、円周方向に関して大きな圧縮応力が残留している。従って、この内輪３の損傷防止を図る面からは、上記かしめ工程で、上記熱処理工程及び研磨工程でこの内輪３に生じさせた圧縮応力がどの程度まで減少するか（引っ張り応力を低く抑えられるか）が重要になる。次の表４に、上記かしめ加工後に、上記内輪３端面、及びこの内輪３面取り部分に存在する、円周方向の残留応力の値を示している。   In any case, in the caulking step, as the cylindrical portion 10 is processed into the caulking portion 9, the processed portion is plastically deformed radially outward. For this reason, the said inner ring | wheel 3 externally fitted by the circumference | surroundings of this process part tends to be expanded radially. As a result, a tensile stress in the circumferential direction is applied to the inner ring 3 as the caulking process proceeds. As shown in Tables 2 and 3, a large compressive stress in the circumferential direction remains in the single body of the inner ring 3 by the heat treatment process and the grinding process. Therefore, from the aspect of preventing damage to the inner ring 3, to what extent the compressive stress generated in the inner ring 3 is reduced in the caulking step in the heat treatment step and the polishing step (is it possible to keep the tensile stress low)? ) Becomes important. Table 4 below shows the residual stress values in the circumferential direction existing on the end face of the inner ring 3 and the chamfered portion of the inner ring 3 after the caulking process.

Figure 2005098475
Figure 2005098475

この表４の左欄から明らかな通り、かしめ加工後の状態で、上記内輪３の端面には、円周方向に関して、−３００ＭＰａ以上の、大きな圧縮応力が残留している。この様に、上記内輪３の端面に圧縮応力を残留させれば、腐食環境下でも、この内輪３の端面に亀裂が生じる事はない。又、上記表４の右欄は、かしめ加工後の状態で、上記内輪３の端面外周縁部の面取り部分に存在する、円周方向の応力の状態を示している。この面取り部分の残留応力は引っ張り応力であるが、２００ＭＰａ以下の小さな値に抑えられている。前述した腐食環境下の試験から明らかな通り、円周方向の残留引っ張り応力（フープ応力）の値が４００ＭＰａ以下であれば、通常考えられる使用状態での、腐蝕に基づく遅れ破壊の発生は防止できる。従って、上記面取り部分に存在する残留引っ張り応力に拘らず、上記内輪３に遅れ破壊等の損傷が発生する事はない。特に、上記内輪３の端面と同様、この内輪３の表面は、上記面取り部を除く殆どの部分に、円周方向に関して圧縮応力が残留している。引っ張り応力が残留するのは、尖っている僅かな部分のみである。しかも、この部分の引っ張り残留応力が、安全を見た値である、３００ＭＰａ以下に抑えられているので、腐食環境下でも、上記損傷の発生を防止できる。   As is apparent from the left column of Table 4, a large compressive stress of −300 MPa or more remains in the end surface of the inner ring 3 in the circumferential direction in the state after the caulking process. Thus, if compressive stress remains on the end face of the inner ring 3, the end face of the inner ring 3 will not crack even in a corrosive environment. The right column of Table 4 shows the state of stress in the circumferential direction that exists in the chamfered portion of the outer peripheral edge of the end face of the inner ring 3 after the caulking process. The residual stress in this chamfered portion is a tensile stress, but is suppressed to a small value of 200 MPa or less. As is clear from the above-mentioned test under a corrosive environment, if the value of the residual tensile stress (hoop stress) in the circumferential direction is 400 MPa or less, it is possible to prevent the occurrence of delayed fracture due to corrosion in a normal use state. . Therefore, no damage such as delayed fracture occurs in the inner ring 3 regardless of the residual tensile stress present in the chamfered portion. In particular, as with the end face of the inner ring 3, the surface of the inner ring 3 has a compressive stress remaining in the circumferential direction in almost all portions except the chamfered portion. The tensile stress remains only in a small pointed portion. In addition, since the tensile residual stress at this portion is suppressed to 300 MPa or less, which is a safe value, the occurrence of the damage can be prevented even in a corrosive environment.

尚、上記内輪３の表面に圧縮応力を残留させる方法としては、前述した様に、この内輪３にバニシング加工やショットプラストを施す事も考えられ、何れの場合も、腐食環境下に於ける損傷防止の面から効果を得られる。
又、残留応力に関するＸ線測定データを示した表２〜４の値は、測定結果の代表例である。
更に、本発明を実施する構造は、前述の図１に示した構造に限らず、前述の図４に示した構造、更には、図示はしないが、駆動輪用の車輪支持用転がり軸受ユニットも対象となる。何れの構造でも、かしめ部で内輪を抑え付ける構造であれば、本発明の作用・効果を得られる。 As described above, the inner ring 3 may be subjected to burnishing or shot plasting as a method for causing the compressive stress to remain on the surface of the inner ring 3. In any case, damage in a corrosive environment may be considered. The effect can be obtained from the aspect of prevention.
The values in Tables 2 to 4 showing X-ray measurement data relating to residual stress are typical examples of measurement results.
Furthermore, the structure for carrying out the present invention is not limited to the structure shown in FIG. 1 described above, and the structure shown in FIG. 4 described above. Further, although not shown, a wheel bearing rolling bearing unit for driving wheels is also provided. It becomes a target. In any structure, the function and effect of the present invention can be obtained as long as the inner ring is suppressed by the caulking portion.

本発明の対象となる車輪支持用転がり軸受ユニットの第１例を示す半部断面図。The half part sectional view showing the 1st example of the rolling bearing unit for wheel support used as the object of the present invention. この第１例の構造の製造時に内輪を固定する為、ハブの内端部をかしめ広げる状態を示す部分拡大断面図。The partial expanded sectional view which shows the state which crimps the inner end part of a hub in order to fix an inner ring | wheel at the time of manufacture of the structure of this 1st example. 同じくハブの内端部をかしめ広げる以前の状態で示す部分拡大断面図。The partial expanded sectional view shown in the state before caulking the inner end part of a hub similarly. 本発明の対象となる車輪支持用転がり軸受ユニットの第２例を示す断面図。Sectional drawing which shows the 2nd example of the rolling bearing unit for wheel support used as the object of this invention. 揺動プレス装置によりハブの内端部をかしめ広げる状態を示す要部縦断面図。The principal part longitudinal cross-sectional view which shows the state which crimps and expands the inner end part of a hub with a rocking press apparatus. 内輪の断面形状の２例を示す部分断面図。The fragmentary sectional view which shows two examples of the cross-sectional shape of an inner ring | wheel. 角部の断面形状を示す部分拡大断面図。The partial expanded sectional view which shows the cross-sectional shape of a corner | angular part. 角部に圧縮応力を残留させない状態での、この角部の断面形状とフープ応力とが遅れ破壊に及ぼす影響を示すグラフ。The graph which shows the influence which the cross-sectional shape of this corner | angular part and the hoop stress exert on delayed fracture in the state which does not leave compressive stress in a corner | angular part. 角部に圧縮応力を残留させた状態での、この角部の断面形状とフープ応力とが遅れ破壊に及ぼす影響を示すグラフ。The graph which shows the influence which the cross-sectional shape of this corner | angular part and the hoop stress exert on delayed fracture in the state which left the compressive stress in the corner | angular part. 内輪の両端面を研削する為の装置の略断面図。The schematic sectional drawing of the apparatus for grinding the both end surfaces of an inner ring | wheel. 同じく略斜視図。FIG.

符号の説明Explanation of symbols

１、１ａ 車輪支持用転がり軸受ユニット
２、２ａ ハブ
３、３ａ、３ｂ 内輪
４ 外輪
５ 転動体
６、６ａ 第一のフランジ
７、７ａ 第一の内輪軌道
８、８ａ 段部
９、９ａ、９ｂ かしめ部
１０、１０ａ 円筒部
１１ テーパ孔
１２ 押型
１３ 凸部
１４ 凹部
１５ 段差面
１６、１６ａ 第一の外輪軌道
１７、１７ａ 第二の内輪軌道
１８、１８ａ 第二の外輪軌道
１９ 保持器
２０、２０ａ 第二のフランジ
２１ 軸部材
２２ 揺動プレス装置
２３ 抑え治具
２４ ホルダ
２５ カバー
２６ シールリング
２７ａ、２７ｂ 砥石
２８ ロータリキャリア
２９ ポケット DESCRIPTION OF SYMBOLS 1, 1a Rolling bearing unit for wheel support 2, 2a Hub 3, 3a, 3b Inner ring 4 Outer ring 5 Rolling element 6, 6a First flange 7, 7a First inner ring raceway 8, 8a Step part 9, 9a, 9b Caulking Part 10, 10a Cylindrical part 11 Tapered hole 12 Stamping die 13 Convex part 14 Concave part 15 Stepped surface 16, 16a First outer ring raceway 17, 17a Second inner ring raceway 18, 18a Second outer ring raceway 19 Cage 20, 20a First Second flange 21 Shaft member 22 Oscillating press device 23 Holding jig 24 Holder 25 Cover 26 Seal ring 27a, 27b Grinding stone 28 Rotary carrier 29 Pocket

Claims (10)

外周面に第一の内輪軌道を一体又は別体の内輪を介して有する内径側部材と、この内径側部材の端部に外嵌された、外周面に第二の内輪軌道を有する鋼製の内輪と、内周面にこれら第一、第二の内輪軌道に対向する第一、第二の外輪軌道を有する外径側部材と、これら第一、第二の内輪軌道とこれら第一、第二の外輪軌道との間に、それぞれ複数個ずつ設けられた転動体とを備え、上記内径側部材の端部で少なくともこの内径側部材に外嵌した内輪よりも突出した部分に形成した円筒部を直径方向外方にかしめ広げる事で形成したかしめ部により、上記内径側部材に外嵌した内輪をこの内径側部材に結合固定した車輪支持用転がり軸受ユニットに於いて、上記かしめ部の加工に伴って上記内輪の表面に加わるフープ応力が３００ＭＰａ以下である事を特徴とする車輪支持用転がり軸受ユニット。   An inner diameter side member having the first inner ring raceway on the outer peripheral surface through an integral or separate inner ring, and a steel made of steel having a second inner ring raceway on the outer peripheral surface that is externally fitted to the end of the inner diameter side member. An inner ring, an outer diameter side member having first and second outer ring raceways opposed to the first and second inner ring raceways on the inner peripheral surface, the first and second inner ring raceways, and the first and second A plurality of rolling elements provided between each of the two outer ring raceways, and a cylindrical portion formed at an end of the inner diameter side member at a portion protruding from at least the inner ring that is externally fitted to the inner diameter side member In a wheel bearing rolling bearing unit in which an inner ring externally fitted to the inner diameter side member is coupled and fixed to the inner diameter side member by a caulking portion formed by caulking outward in the diameter direction, the caulking portion is processed. Along with this, the hoop stress applied to the surface of the inner ring is 300 MPa or less. Wheel supporting rolling bearing unit which is characterized in that that. 外周面に第一の内輪軌道を一体又は別体の内輪を介して有する内径側部材と、この内径側部材の端部に外嵌された、外周面に第二の内輪軌道を有する鋼製の内輪と、内周面にこれら第一、第二の内輪軌道に対向する第一、第二の外輪軌道を有する外径側部材と、これら第一、第二の内輪軌道とこれら第一、第二の外輪軌道との間に、それぞれ複数個ずつ設けられた転動体とを備え、上記内径側部材の端部で少なくともこの内径側部材に外嵌した内輪よりも突出した部分に形成した円筒部を直径方向外方にかしめ広げる事で形成したかしめ部により、上記内径側部材に外嵌した内輪をこの内径側部材に結合固定した車輪支持用転がり軸受ユニットに於いて、この内輪の外周面と、この内輪の軸方向両端面のうちで上記かしめ部が設けられた側の端面とが交差する角部に、上記かしめ部の加工に伴って上記角部に加わるフープ応力が、３００ＭＰａ以下である事を特徴とする車輪支持用転がり軸受ユニット。   An inner diameter side member having the first inner ring raceway on the outer peripheral surface through an integral or separate inner ring, and a steel made of steel having a second inner ring raceway on the outer peripheral surface that is externally fitted to the end of the inner diameter side member. An inner ring, an outer diameter side member having first and second outer ring raceways opposed to the first and second inner ring raceways on the inner peripheral surface, the first and second inner ring raceways, and the first and second A plurality of rolling elements provided between each of the two outer ring raceways, and a cylindrical portion formed at an end of the inner diameter side member at a portion protruding from at least the inner ring that is externally fitted to the inner diameter side member In a wheel bearing rolling bearing unit in which an inner ring externally fitted to the inner diameter side member is coupled and fixed to the inner diameter side member by a caulking portion formed by caulking outward in the diameter direction, the outer peripheral surface of the inner ring Of the both axial end surfaces of the inner ring, the side where the caulking portion is provided The corner surface and intersect the hoop stress applied to the corner portion with the processing of the crimped portion, the wheel support rolling bearing unit, characterized in that at most 300 MPa. 内輪の外周面と、この内輪の軸方向両端面のうちでかしめ部が設けられた側の端面とが交差する角部が、断面形状が円弧形で軸方向寸法及び径方向寸法が何れも１．０mm以上である凸曲面とされており、且つ、上記かしめ部の加工に伴って上記角部に加わるフープ応力が４０〜３００ＭＰａの範囲に規制されている、請求項２に記載した車輪支持用転がり軸受ユニット。   The corner where the outer ring surface of the inner ring intersects the end surface on the side where the caulking portion is provided on both axial end surfaces of the inner ring has a circular cross-sectional shape, and both the axial dimension and the radial dimension are The wheel support according to claim 2, wherein the wheel support is a convex curved surface of 1.0 mm or more, and a hoop stress applied to the corner portion in accordance with the processing of the caulking portion is regulated within a range of 40 to 300 MPa. Rolling bearing unit for use. 外周面に第一の内輪軌道を一体又は別体の内輪を介して有する内径側部材と、この内径側部材の端部に外嵌された、外周面に第二の内輪軌道を有する鋼製の内輪と、内周面にこれら第一、第二の内輪軌道に対向する第一、第二の外輪軌道を有する外径側部材と、これら第一、第二の内輪軌道とこれら第一、第二の外輪軌道との間に、それぞれ複数個ずつ設けられた転動体とを備え、上記内径側部材の端部で少なくともこの内径側部材に外嵌した内輪よりも突出した部分に形成した円筒部を直径方向外方にかしめ広げる事で形成したかしめ部により、上記内径側部材に外嵌した内輪をこの内径側部材に結合固定した車輪支持用転がり軸受ユニットに於いて、この内輪の軸方向両端面のうちで上記かしめ部が設けられた側の端面のうちの少なくとも一部分に、円周方向の残留圧縮応力が存在する事を特徴とする車輪支持用転がり軸受ユニット。   An inner diameter side member having the first inner ring raceway on the outer peripheral surface through an integral or separate inner ring, and a steel made of steel having a second inner ring raceway on the outer peripheral surface that is externally fitted to the end of the inner diameter side member. An inner ring, an outer diameter side member having first and second outer ring raceways opposed to the first and second inner ring raceways on the inner peripheral surface, the first and second inner ring raceways, and the first and second A plurality of rolling elements provided between each of the two outer ring raceways, and a cylindrical portion formed at an end of the inner diameter side member at a portion protruding from at least the inner ring that is externally fitted to the inner diameter side member In a rolling bearing unit for supporting a wheel in which an inner ring externally fitted to the inner diameter side member is coupled and fixed to the inner diameter side member by caulking portions formed by caulking outward in the diameter direction, both axial ends of the inner ring At least one of the end faces on the side where the caulking portion is provided. A portion, a wheel support rolling bearing unit, characterized in that the residual compressive stress in the circumferential direction is present. 内輪の外周面と、この内輪の軸方向両端面のうちでかしめ部が設けられた側の端面とが交差する角部が、この内輪に焼き入れ、焼き戻しを含む熱処理を施した後に行なわれる、研削加工、旋削加工、バニシング加工のうちから選択される何れかの加工により、断面形状が円弧形で軸方向寸法及び径方向寸法が何れも１．０mm以上であって、表面から５０〜１００μｍの深さ部分の残留圧縮応力が２００ＭＰａ以上である凸曲面とされており、且つ、上記かしめ部の加工に伴って上記角部に加わるフープ応力が４０〜３５０ＭＰａの範囲に規制されている、請求項４に記載した車輪支持用転がり軸受ユニット。   A corner portion where the outer peripheral surface of the inner ring intersects the end surface on the side where the caulking portion is provided in both axial end surfaces of the inner ring is performed after the inner ring is subjected to heat treatment including quenching and tempering. , Grinding process, turning process, burnishing process, the cross-sectional shape is an arc shape, the axial dimension and the radial dimension are both 1.0 mm or more, and 50 to 50 The convex compressive surface has a residual compressive stress of 200 MPa or more at a depth portion of 100 μm, and the hoop stress applied to the corner portion in connection with the processing of the caulking portion is regulated within a range of 40 to 350 MPa. The wheel bearing rolling bearing unit according to claim 4. 凸曲面の軸方向寸法が１．５mm以上である、請求項３、５の何れかに記載した車輪支持用転がり軸受ユニット。   The wheel bearing rolling bearing unit according to any one of claims 3 and 5, wherein an axial dimension of the convex curved surface is 1.5 mm or more. 角部の凸曲面の表面粗さを０．２μｍＲａ以下とした、請求項３、５、６の何れかに記載した車輪支持用転がり軸受ユニット。   The rolling bearing unit for supporting a wheel according to any one of claims 3, 5, and 6, wherein the surface roughness of the convex curved surface of the corner portion is 0.2 µmRa or less. 請求項４又は請求項５に記載した車輪支持用転がり軸受ユニットを造る際に、表面を研削工程した後、かしめ部によりその端面を抑え付けられる以前の状態で、その両端面のうちのこのかしめ部側の端面に円周方向の圧縮応力が残留している内輪を使用する事を特徴とする車輪支持用転がり軸受ユニットの製造方法。   When the rolling bearing unit for supporting a wheel according to claim 4 or 5 is manufactured, after the surface is ground, the caulking portion is in a state before the end surface is suppressed by the caulking portion. A method for manufacturing a wheel-supporting rolling bearing unit, characterized in that an inner ring in which a circumferential compressive stress remains on an end surface on the part side is used. 請求項４又は請求項５に記載した車輪支持用転がり軸受ユニットを造る際に、熱処理後に、その両端面のうちのかしめ部側の端面に円周方向の圧縮応力が残留している内輪を使用する事を特徴とする車輪支持用転がり軸受ユニットの製造方法。   When the rolling bearing unit for supporting a wheel according to claim 4 or 5 is manufactured, an inner ring in which circumferential compressive stress remains on the end face on the caulking portion side of both end faces after heat treatment is used. A method for manufacturing a wheel-supporting rolling bearing unit. 請求項１〜７の何れかに記載した車輪支持用転がり軸受ユニットを造る際に、Ｘ線測定法により内輪に存在する残留応力を測定する事を特徴とする車輪支持用転がり軸受ユニットの製造方法。   A method for manufacturing a wheel-supporting rolling bearing unit, characterized in that, when the wheel-supporting rolling bearing unit according to any one of claims 1 to 7 is manufactured, residual stress existing in the inner ring is measured by an X-ray measurement method. .
JP2003374679A 2003-08-20 2003-11-04 Rolling bearing unit for supporting wheel, and method for manufacturing the same Pending JP2005098475A (en)

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Cited By (9)

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JP2007024148A (en) * 2005-07-14 2007-02-01 Ntn Corp Wheel bearing device
WO2007029658A1 (en) * 2005-09-09 2007-03-15 Ntn Corporation Bearing device for wheel
JP2007239965A (en) * 2006-03-13 2007-09-20 Ntn Corp Bearing device for wheel
JP2008256019A (en) * 2007-04-02 2008-10-23 Jtekt Corp Wheel rolling bearing device, and method of manufacturing the same
JP2009293731A (en) * 2008-06-06 2009-12-17 Ntn Corp Bearing device for wheel
US7648284B2 (en) * 2004-05-17 2010-01-19 Ntn Corporation Bearing apparatus for a wheel of vehicle
JP2010144923A (en) * 2008-12-22 2010-07-01 Ntn Corp Inner ring of rolling bearing, and bearing device for wheel equipped with the same
CN106224375A (en) * 2016-08-31 2016-12-14 陕西天翌天线有限公司 A kind of revolving support mechanism
JP2021126682A (en) * 2020-02-14 2021-09-02 株式会社オティックス Shank base material, shank member assembling method and lifter

Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US7648284B2 (en) * 2004-05-17 2010-01-19 Ntn Corporation Bearing apparatus for a wheel of vehicle
JP2007024148A (en) * 2005-07-14 2007-02-01 Ntn Corp Wheel bearing device
JP4632305B2 (en) * 2005-07-14 2011-02-16 Ｎｔｎ株式会社 Wheel bearing device
WO2007029658A1 (en) * 2005-09-09 2007-03-15 Ntn Corporation Bearing device for wheel
JP2007071358A (en) * 2005-09-09 2007-03-22 Ntn Corp Wheel bearing device
JP2007239965A (en) * 2006-03-13 2007-09-20 Ntn Corp Bearing device for wheel
JP2008256019A (en) * 2007-04-02 2008-10-23 Jtekt Corp Wheel rolling bearing device, and method of manufacturing the same
JP2009293731A (en) * 2008-06-06 2009-12-17 Ntn Corp Bearing device for wheel
JP2010144923A (en) * 2008-12-22 2010-07-01 Ntn Corp Inner ring of rolling bearing, and bearing device for wheel equipped with the same
CN106224375A (en) * 2016-08-31 2016-12-14 陕西天翌天线有限公司 A kind of revolving support mechanism
JP2021126682A (en) * 2020-02-14 2021-09-02 株式会社オティックス Shank base material, shank member assembling method and lifter
JP7368262B2 (en) 2020-02-14 2023-10-24 株式会社オティックス lifter

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