JP4278542B2 - Manufacturing method of wheel supporting hub unit - Google Patents

Manufacturing method of wheel supporting hub unit Download PDF

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JP4278542B2
JP4278542B2 JP2004078809A JP2004078809A JP4278542B2 JP 4278542 B2 JP4278542 B2 JP 4278542B2 JP 2004078809 A JP2004078809 A JP 2004078809A JP 2004078809 A JP2004078809 A JP 2004078809A JP 4278542 B2 JP4278542 B2 JP 4278542B2
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inner ring
peripheral surface
outer peripheral
outer diameter
caulking
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JP2005291216A (en
JP2005291216A5 (en
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弘樹 志村
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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
    • 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
    • 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

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為に使用する車輪支持用ハブユニットの製造方法の改良に関する。 The present invention relates to an improvement in a method for manufacturing a wheel-supporting hub unit used for rotatably supporting a wheel of an automobile with respect to a suspension device.

自動車の車輪は、車輪支持用ハブユニットにより懸架装置に支持する。図８は、この様な車輪支持用ハブユニットの従来構造の第１例として、駆動輪（ＦＦ車の前輪、ＦＲ車及びＲＲ車の後輪、４ＷＤ車の全車輪）用のものを示している。この車輪支持用ハブユニット１は、軸部材であるハブ２と、内輪３と、外輪４と、複数個の転動体５、５とを備える。   The wheels of the automobile are supported on the suspension device by a wheel supporting hub unit. FIG. 8 shows a first example of such a conventional wheel support hub unit for driving wheels (front wheels of FF vehicles, rear wheels of FR and RR vehicles, all wheels of 4WD vehicles). Yes. The wheel support hub unit 1 includes a hub 2 that is a shaft member, an inner ring 3, an outer ring 4, and a plurality of rolling elements 5 and 5.

このうちのハブ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、８、９、１０の左側。反対に軸方向に関して「内」とは、車両の幅方向中央側を言い、図１、８、９、１０の右側。本明細書全体で同じ。）寄り部分には、車輪を支持固定する為の取付フランジ６を、同じく中間部には第一の内輪軌道７ａを、同じく内端部にはこの第一の内輪軌道７ａを形成した部分よりも外径寸法が小さくなった小径段部８を、それぞれ形成している。尚、上記第一の内輪軌道７ａは、図示の様に上記ハブ２の中間部外周面に直接形成する場合の他、ハブ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。この場合には、ハブの外周面の内端部でこの別体の内輪よりも突出した部分が上記小径段部８となり、この別体の内輪の内端面が、後述する段差面９となる。又、上記ハブ２の中心部には、駆動軸であるスプライン軸を係合させる為のスプライン孔１０を設けている。   Of these, the outer end of the outer peripheral surface of the hub 2 ("outside" with respect to the axial direction refers to the outer side in the width direction of the vehicle in the assembled state to the automobile, and is the left side of FIGS. “Inside” means the center side in the width direction of the vehicle, and is the right side of FIGS. 1, 8, 9, and 10. The same applies to the whole of this specification. Similarly, a first inner ring raceway 7a is formed at the intermediate portion, and a small diameter step portion 8 having an outer diameter smaller than that of the portion where the first inner ring raceway 7a is formed is formed at the inner end portion. ing. The first inner ring raceway 7a is formed directly on the outer peripheral surface of the intermediate portion of the hub 2 as shown in the drawing, or on the outer peripheral surface of a separate inner ring that is fitted around the intermediate portion of the hub. There is also. In this case, the portion protruding from the separate inner ring at the inner end portion of the outer peripheral surface of the hub becomes the small-diameter stepped portion 8, and the inner end surface of the separate inner ring becomes the step surface 9 described later. Further, a spline hole 10 for engaging a spline shaft as a drive shaft is provided at the center of the hub 2.

又、上記内輪３は、外周面に第二の内輪軌道７ｂを有すると共に、上記小径段部８に外嵌している。又、上記外輪４は、外周面に懸架装置に結合固定する為の結合フランジ１１を、内周面に第一、第二の外輪軌道１２ａ、１２ｂを、それぞれ形成している。そして、これら第一、第二の各外輪軌道１２ａ、１２ｂと、上記第一、第二の各内輪軌道７ａ、７ｂとの間に、それぞれ複数個ずつの転動体５、５を設けている。尚、図示の例では、これら各転動体５、５として玉を使用しているが、重量の嵩む自動車用の車輪支持用ハブ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。   The inner ring 3 has a second inner ring raceway 7b on the outer peripheral surface and is externally fitted to the small diameter step portion 8. The outer ring 4 has a coupling flange 11 for coupling and fixing to a suspension device on the outer peripheral surface, and first and second outer ring raceways 12a and 12b on the inner peripheral surface, respectively. A plurality of rolling elements 5 and 5 are provided between the first and second outer ring raceways 12a and 12b and the first and second inner ring raceways 7a and 7b, respectively. In the illustrated example, balls are used as the rolling elements 5 and 5. However, in the case of a heavy wheel supporting hub unit for automobiles, tapered rollers may be used as the rolling elements. is there.

更に、上記ハブ２の内端部に設けた円筒部１３のうち、上記内輪３の内端面から軸方向に突出した部分を径方向外方に向け、ローリングプレス加工（揺動かしめ）等により塑性変形させる事で、かしめ部１４を形成している。そして、このかしめ部１４により、上記内輪３を、上記小径段部８の基端部に存在する段差面９に向け抑え付けている。そして、このかしめ部１４による抑え付け力により、上記各転動体５、５に予圧を付与している。   Further, of the cylindrical portion 13 provided at the inner end portion of the hub 2, the portion protruding in the axial direction from the inner end surface of the inner ring 3 is directed outward in the radial direction, and is plasticized by rolling press working (swing caulking) or the like. The caulking portion 14 is formed by deforming. The caulking portion 14 holds the inner ring 3 toward the stepped surface 9 existing at the proximal end portion of the small-diameter stepped portion 8. A preload is applied to each of the rolling elements 5 and 5 by the pressing force of the caulking portion 14.

又、図示の例では、上記内輪３の外周面の内端部に、上記第二の内輪軌道７ｂの肩部１５よりも外径寸法が小さくなった小径段部１６を、全周に亙り形成している。これにより、上記内輪３の径方向に関する肉厚を、上記肩部１５に対応する部分よりも、上記小径段部１６に対応する部分で小さくしている。この様な小径段部１６は、車輪の回転速度を検出する為に利用する、円環状のエンコーダの取り付け個所（被嵌合部）となる。   In the illustrated example, a small-diameter step portion 16 having an outer diameter smaller than that of the shoulder portion 15 of the second inner ring raceway 7b is formed over the entire circumference at the inner end portion of the outer peripheral surface of the inner ring 3. is doing. Thereby, the thickness in the radial direction of the inner ring 3 is made smaller at the portion corresponding to the small diameter step portion 16 than at the portion corresponding to the shoulder portion 15. Such a small-diameter step portion 16 serves as a mounting portion (a fitted portion) of an annular encoder used for detecting the rotational speed of the wheel.

尚、上述の様な車輪支持用ハブユニットを構成する各部材のうち、上記ハブ２及び外輪４は、フランジ部や孔部等を有しており、全体的に複雑な形状をしている。この為、一般に、これらハブ２及び外輪４は、熱間鍛造性、切削加工性、及び孔あけ加工性等が良好な、０．５重量％程度の炭素を含有する中炭素鋼により造る。又、上記第一の内輪軌道７ａを含む上記ハブ２の中間部外周面、並びに、上記第一、第二の各外輪軌道１２ａ、１２ｂを含む上記外輪４の内周面には、それぞれ高周波焼入れによる硬化処理を施す。又、上述の様な車輪支持用ハブユニットの使用時には、上記ハブ２の外周面に設けた第一の内輪軌道７ａよりも、上記内輪３の外周面に設けた第二の内輪軌道７ｂの方に、より高い荷重が負荷される。この為、一般に、上記内輪３は、ＳＵＪ２等の高炭素クロム鋼により造ると共に、表面から心部まで、熱処理により硬化させる。   Of the members constituting the wheel supporting hub unit as described above, the hub 2 and the outer ring 4 have a flange portion, a hole portion, and the like, and have a complicated shape as a whole. Therefore, in general, the hub 2 and the outer ring 4 are made of a medium carbon steel containing about 0.5% by weight of carbon, which has good hot forgeability, cutting workability, drilling workability, and the like. In addition, the outer peripheral surface of the intermediate portion of the hub 2 including the first inner ring raceway 7a and the inner peripheral surface of the outer ring 4 including the first and second outer ring raceways 12a and 12b are induction-hardened, respectively. A curing process is applied. When the wheel supporting hub unit as described above is used, the second inner ring raceway 7b provided on the outer peripheral surface of the inner ring 3 is more than the first inner ring raceway 7a provided on the outer peripheral surface of the hub 2. Further, a higher load is applied. For this reason, in general, the inner ring 3 is made of high carbon chrome steel such as SUJ2 and hardened from the surface to the core by heat treatment.

次に、図９は、車輪支持用ハブユニットの従来構造の第２例として、従動輪（ＦＦ車の後輪、ＦＲ車及びＲＲ車の前輪）用のものを示している。本例の車輪支持用ハブユニット１ａは従動輪用である為、軸部材であるハブ２ａの中心部には、スプライン孔を設けていない。又、図示の例の場合、内輪３ａの内端部外周面には、小径段部を設けていない。その他の部分の構造及び作用は、上述図８に示した車輪支持用ハブユニット１の場合とほぼ同様である。   Next, FIG. 9 shows a driven wheel (rear wheel of FF vehicle, front wheel of FR vehicle and RR vehicle) as a second example of the conventional structure of the wheel supporting hub unit. Since the wheel supporting hub unit 1a of this example is for a driven wheel, a spline hole is not provided in the central portion of the hub 2a which is a shaft member. In the case of the illustrated example, a small-diameter step portion is not provided on the outer peripheral surface of the inner end portion of the inner ring 3a. The structure and operation of the other parts are almost the same as in the case of the wheel supporting hub unit 1 shown in FIG.

次に、図１０は、車輪支持用ハブユニットの従来構造の第３例として、やはり従動輪用のものを示している。本例の車輪支持用ハブユニット１ｂは、外輪４ａの外端寄り部分の外周面に車輪を支持固定する為のフランジ６を設けると共に、この外輪４ａの径方向内側に設けた軸部材１７の内端部に、この軸部材１７を懸架装置に結合固定する為の結合フランジ１１を設けている。又、第二の内輪軌道７ｂを上記軸部材１７の中間部外周面に直接形成すると共に、第一の内輪軌道７ａを、この軸部材１７の外端部に設けた小径段部８に外嵌した内輪３ａの外周面に形成している。又、この小径段部８に外嵌した内輪３ａは、上記軸部材１７の外端部に設けた円筒部１３のうち、この小径段部８に外嵌した内輪３ａよりも軸方向外方に突出した部分を径方向外方に塑性変形させて形成したかしめ部１４により、上記小径段部８の段差面９に向け抑え付けている。そして、このかしめ部１４による抑え付け力により、複数個の転動体５、５に予圧を付与している。   Next, FIG. 10 shows a driven wheel as a third example of the conventional structure of the wheel supporting hub unit. The wheel support hub unit 1b of this example is provided with a flange 6 for supporting and fixing a wheel on the outer peripheral surface of the outer ring 4a near the outer end, and an inner portion of a shaft member 17 provided on the radially inner side of the outer ring 4a. A coupling flange 11 for coupling and fixing the shaft member 17 to the suspension device is provided at the end. Further, the second inner ring raceway 7b is formed directly on the outer peripheral surface of the intermediate portion of the shaft member 17, and the first inner ring raceway 7a is externally fitted to the small diameter step portion 8 provided at the outer end portion of the shaft member 17. Formed on the outer peripheral surface of the inner ring 3a. The inner ring 3a externally fitted to the small-diameter step portion 8 is axially outward of the inner ring 3a externally fitted to the small-diameter step portion 8 in the cylindrical portion 13 provided at the outer end portion of the shaft member 17. The protruding portion is pressed against the step surface 9 of the small-diameter step portion 8 by a caulking portion 14 formed by plastic deformation outward in the radial direction. A preload is applied to the plurality of rolling elements 5 and 5 by the pressing force of the caulking portion 14.

ところで、上述した様な各車輪支持用ハブユニット１、１ａ、１ｂの場合、かしめ部１４は、複数の転動体５、５に予圧を付与する役割と、軸部材（２、２ａ、１７）と内輪（３、３ａ）との嵌合部でクリープ（円周方向の滑り）が発生するのを防止する役割とを果たす、重要な部位である。上記かしめ部１４が適切に形成されていないと、上記予圧が過大又は過小となったり、或はクリープが発生して上記内輪（３、３ａ）の嵌合部が摩耗する等により、上記予圧が低下する。これらの事態は何れも、転がり疲れ寿命を低下させる原因となる為、好ましくない。従って、製造時には、上記かしめ部１４が適切に形成されているか否かを管理する事が重要となる。この為に従来から、例えば特許文献１に記載されている様な方法により、上記かしめ部１４の軸力を測定し、この軸力の値に基づいて、上記かしめ部１４が適切に形成されているか否かを管理する事が行なわれている。   By the way, in the case of each wheel supporting hub unit 1, 1 a, 1 b as described above, the caulking portion 14 has a role of applying a preload to the plurality of rolling elements 5, 5, and shaft members (2, 2 a, 17). This is an important part that plays the role of preventing creep (slip in the circumferential direction) from occurring at the fitting portion with the inner ring (3, 3a). If the caulking portion 14 is not properly formed, the preload may be excessive or small, or creep may be generated and the fitting portion of the inner ring (3, 3a) may be worn. descend. Any of these situations is not preferable because it causes a reduction in rolling fatigue life. Therefore, at the time of manufacture, it is important to manage whether or not the caulking portion 14 is appropriately formed. For this reason, conventionally, the axial force of the caulking portion 14 is measured by a method as described in Patent Document 1, for example, and the caulking portion 14 is appropriately formed based on the value of the axial force. Whether or not it is managed.

一方、上述した様な各車輪支持用ハブユニット１、１ａ、１ｂの場合、上記軸部材（２、２ａ、１７）の小径段部８に上記内輪（３、３ａ）を圧入嵌合させる事に伴い、更にはこの内輪（３、３ａ）を上記かしめ部１４により抑え付ける事に伴い、この内輪（３、３ａ）に大きなフープ応力（円周方向の引っ張り応力）が発生する。このフープ応力が過大になると、軸受部｛特に、上記内輪（３、３ａ）の外周面に形成した第二の内輪軌道７ｂ｝の転がり疲れ寿命が低下する。この為、本来、このフープ応力は、上記かしめ部１４の形成管理を行なう際の重要な判断要素となる。これに対し、従来は、上述した様に、このかしめ部１４の形成管理を、このかしめ部１４の軸力を測定する事に基づいて行なっている。ところが、この様にかしめ部１４の軸力を測定するだけでは、上記フープ応力が過大になっているか否かを判断する事が難しい。従って、転がり疲れ寿命の信頼性を向上させるべく、上記かしめ部１４の形成管理を適切に行なう為には、このかしめ部１４の形成管理を、上記フープ応力を測定する事に基づいて行なうのが好ましい。   On the other hand, in the case of each wheel supporting hub unit 1, 1 a, 1 b as described above, the inner ring (3, 3 a) is press-fitted into the small diameter step portion 8 of the shaft member (2, 2 a, 17). Along with this, the inner ring (3, 3a) is restrained by the caulking portion 14, and a large hoop stress (circumferential tensile stress) is generated in the inner ring (3, 3a). When this hoop stress becomes excessive, the rolling fatigue life of the bearing portion {particularly, the second inner ring raceway 7b formed on the outer peripheral surface of the inner ring (3, 3a)} is reduced. For this reason, the hoop stress is essentially an important determination factor when the formation management of the caulking portion 14 is performed. On the other hand, conventionally, as described above, the formation management of the caulking portion 14 is performed based on measuring the axial force of the caulking portion 14. However, it is difficult to determine whether or not the hoop stress is excessive only by measuring the axial force of the caulking portion 14 in this way. Accordingly, in order to appropriately perform the formation management of the caulking portion 14 in order to improve the reliability of the rolling fatigue life, the formation management of the caulking portion 14 is performed based on the measurement of the hoop stress. preferable.

特開２００３−１３９７９号公報JP 2003-13979 A

本発明の車輪支持用ハブユニットの製造方法は、上述の様な事情に鑑み、内輪に発生するフープ応力の値に基づいてかしめ部が適切に形成されているか否かを判定する事により、転がり疲れ寿命に関する信頼性の高い製品を出荷できる様にすべく発明したものである。 In view of the circumstances as described above, the wheel support hub unit manufacturing method according to the present invention rolls by determining whether or not the caulking portion is appropriately formed based on the value of the hoop stress generated in the inner ring. The invention was invented so that products with high fatigue life could be shipped.

本発明の製造方法の対象となる車輪支持用ハブユニットは、軸部材の一端部に設けた小径段部に内輪を外嵌すると共に、この内輪の一端面を、この軸部材の一端部に設けた円筒部のうちこの内輪の一端面から突出した部分を径方向外方に塑性変形させて形成したかしめ部により抑え付ける事で、上記内輪を上記軸部材に結合固定している。
特に、本発明の車輪支持用ハブユニットの製造方法の場合には、熱処理を施した後に一部外周面に研削加工を施してこの一部外周面の真円度を改善した内輪を、上記小径段部に外嵌する。次いで、上記かしめ部を形成した後に、この内輪の一部外周面で発生しているフープ応力（円周方向の引っ張り応力）を測定する。この引っ張り応力の測定は、上記内輪の一部外周面で上記真円度を改善した部分の外径寸法を、この内輪を上記小径段部に外嵌する前と、上記かしめ部を形成した後とでそれぞれ測定する事により行なう。そして、上記引っ張り応力の値が所定範囲（上限は、転がり疲れ寿命が低下しない値。下限は、軸部材と内輪との嵌合部でクリープが生じない値。）に収まっている場合にのみ、上記かしめ部が適切に形成されていると判定する。又、この様な判定を行なう為、このかしめ部を形成する事に伴って生じた熱により上記内輪が熱膨張したままの状態でこの内輪の一部外周面で上記真円度を改善した部分の外径寸法を測定すると共に、当該測定時の熱膨張に基づく外径寸法の増大量を予め用意しておいた実験データに基づいて推定し、上記測定した外径寸法からこの推定した増大量を差し引いた値を、上記かしめ部を形成した後の上記内輪の一部外周面で上記真円度を改善した部分の外径寸法とする。 A hub unit for supporting a wheel, which is a target of the manufacturing method of the present invention, has an inner ring fitted on a small diameter step provided at one end of a shaft member, and one end surface of the inner ring is provided at one end of the shaft member. The inner ring is coupled and fixed to the shaft member by restraining a portion protruding from one end surface of the inner ring by a caulking part formed by plastic deformation radially outward.
In particular, in the case of the method for manufacturing the wheel supporting hub unit of the present invention, the inner ring whose part of the outer peripheral surface is subjected to grinding after the heat treatment and the roundness of the partial outer peripheral surface is improved, Fits on the step. Next, after the caulking portion is formed, the hoop stress (circumferential tensile stress) generated on a part of the outer peripheral surface of the inner ring is measured. The tensile stress is measured by measuring the outer diameter of the portion of the inner ring where the roundness has been improved on the outer peripheral surface before the outer ring is fitted onto the small diameter step and after the caulking portion is formed. And by measuring each. And only when the value of the tensile stress is within a predetermined range (the upper limit is a value at which the rolling fatigue life does not decrease. The lower limit is a value at which creep does not occur at the fitting portion between the shaft member and the inner ring). It determines with the said crimping part being formed appropriately. Further, in order to make such a determination, the roundness is improved on a part of the outer peripheral surface of the inner ring in a state where the inner ring is still thermally expanded due to heat generated by forming the caulking portion. In addition to measuring the outer diameter of the outer diameter, the amount of increase in the outer diameter based on the thermal expansion at the time of the measurement is estimated based on experimental data prepared in advance, and the estimated amount of increase from the measured outer diameter The value obtained by subtracting is used as the outer diameter of the portion of the inner ring after the caulking portion has been formed and the portion of the inner ring where the roundness has been improved.

上述の様に、本発明の車輪支持用ハブユニットの製造方法の場合には、内輪に発生しているフープ応力の値に基づいて、かしめ部が適切に形成されているか否かを判定する。従って、転がり疲れ寿命に関する信頼性の高い製品のみを出荷する事ができる。
又、上記内輪に熱処理を施すと、これに伴って内輪が変形し、この内輪の一部外周面の真円度が悪化する可能性があるが、本発明の場合には、フープ応力を求める為に外径を測定する、上記内輪の一部外周面の真円度を改善する。この為、この内輪の圧入嵌合及びかしめ部の形成により生じた、当該一部外周面のフープ応力（このフープ応力を計算する為に利用する、この一部外周面の外径寸法を含む。）の測定精度を十分に高める事ができる。従って、転がり疲れ寿命に関する信頼性を十分に向上させる事ができる。
更に、本発明の場合には、上記かしめ部を形成する事に伴って生じた熱により上記内輪が熱膨張したままの状態で、この内輪の一部外周面の外径寸法を測定する。これと共に、当該測定時の熱膨張に基づく外径寸法の増大量を、予め用意しておいた実験データに基づいて推定する。そして、上記測定した外径寸法からこの推定した増大量を差し引いた値を、上記かしめ部を形成した後の上記内輪の一部外周面の外径寸法とする。この為、上記内輪の熱膨張の影響が完全になくなるまでの間（長時間）待機する事なく、上記かしめ部が適切に形成されているか否かの判定を迅速に行なえる。 As described above, in the method of manufacturing the wheel supporting hub unit of the present invention, it is determined whether or not the caulking portion is appropriately formed based on the value of the hoop stress generated in the inner ring. Therefore, only reliable products relating to rolling fatigue life can be shipped.
Further, when the inner ring is heat-treated, the inner ring may be deformed accordingly, and the roundness of a part of the outer peripheral surface of the inner ring may be deteriorated. In the case of the present invention, the hoop stress is obtained. For this purpose, the outer diameter is measured, and the roundness of a part of the outer circumference of the inner ring is improved. For this reason, the hoop stress of the partial outer peripheral surface generated by the press-fitting fitting of the inner ring and the formation of the caulking portion (including the outer diameter of the partial outer peripheral surface used for calculating the hoop stress). ) Measurement accuracy can be sufficiently increased. Therefore, the reliability related to the rolling fatigue life can be sufficiently improved.
Further, in the case of the present invention, the outer diameter of a part of the outer peripheral surface of the inner ring is measured in a state where the inner ring is still thermally expanded due to the heat generated by forming the caulking portion. At the same time, the amount of increase in the outer diameter based on the thermal expansion during the measurement is estimated based on experimental data prepared in advance. Then, a value obtained by subtracting the estimated increase amount from the measured outer diameter dimension is set as an outer diameter dimension of a part of the outer peripheral surface of the inner ring after the caulking portion is formed. Therefore, it is possible to quickly determine whether or not the caulking portion is appropriately formed without waiting for a long time until the influence of the thermal expansion of the inner ring is completely eliminated (for a long time).

本発明を実施する場合に好ましくは、請求項２に記載した発明の様に、内輪の一部外周面の外径寸法を、この内輪を上記小径段部に外嵌する前と、上記かしめ部を形成した後とでそれぞれ測定すると共に、これら各外径寸法の測定値と上記内輪の弾性係数とに基づく応力の計算を行なう事により、フープ応力（円周方向の引っ張り応力）を求める。
この様にして上記フープ応力を測定すれば、例えばこのフープ応力を、上記内輪の一部外周面に歪みゲージを添着して測定する場合に比べて、測定作業を容易にできる。 When carrying out the present invention, preferably, as in the invention described in claim 2, the outer diameter of a part of the outer peripheral surface of the inner ring is measured before the inner ring is externally fitted to the small-diameter step portion and the caulked portion. The hoop stress (circumferential tensile stress) is obtained by measuring each of the outer diameter dimensions and the calculation of stress based on the measured values of the outer diameter dimensions and the elastic coefficient of the inner ring.
If the hoop stress is measured in this way, for example, the measurement work can be facilitated as compared with the case where the hoop stress is measured by attaching a strain gauge to a part of the outer peripheral surface of the inner ring.

又、本発明を実施する場合に、好ましくは、請求項３に記載した発明の様に、研削加工を施した後の上記内輪の一部外周面の真円度を、０．１〜１．５μｍの範囲に規制する。 この様な規制を行なう場合には、上記真円度を０．１μｍ以上とする為、研削加工のコストを抑える事ができる。又、上記真円度を１．５μｍ以下とする為、上記フープ応力（このフープ応力を計算する為に利用する、上記内輪の一部外周面の外径寸法を含む。）の測定精度を十分に高める事ができる。従って、転がり疲れ寿命に関する信頼性を十分に向上させる事ができる。 In carrying out the present invention , preferably, as in the invention described in claim 3 , the roundness of a part of the outer peripheral surface of the inner ring after grinding is 0.1-1. Regulate in the range of 5 μm. When such regulation is performed, the roundness is set to 0.1 μm or more, so that the cost of grinding can be suppressed. In addition, since the roundness is 1.5 μm or less, the measurement accuracy of the hoop stress (including the outer diameter of a part of the outer peripheral surface of the inner ring used for calculating the hoop stress) is sufficient. Can be increased. Therefore, the reliability related to the rolling fatigue life can be sufficiently improved.

又、上述した請求項１〜３の何れかに記載した発明を、例えば転動体のピッチ円直径が５０mm程度（４０〜６０mm）である車輪支持用ハブユニットに対して実施する場合に、好ましくは、請求項４に記載した発明の様に、フープ応力を測定すべき上記内輪の一部外周面を、この内輪の外周面のうち、軸方向に関して上記かしめ部と隣接する側の端部に存在する円筒面部とする。そして、このかしめ部が適切に形成されているか否かの判定基準となる、上記フープ応力の所定範囲を、１５０〜２６０ＭＰａとする。
この様な規制を行なう場合には、上記フープ応力を１５０ＭＰａ以上とする為、軸部材と内輪との密着性を十分に確保する事ができ、これら軸部材と内輪との嵌合部でクリープが発生する事を防止できる。この結果、転がり疲れ寿命が低下する事を防止できる。又、上記フープ応力を２６０ＭＰａ以下とする為、上記内輪の外周面に形成された内輪軌道に作用する、上記フープ応力の影響を十分に抑える事ができる。この結果、軸受部（特に、当該内輪軌道）の転がり疲れ寿命が低下する事を防止できる。 Further, when the invention described in any one of claims 1 to 3 described above is carried out, for example, on a wheel support hub unit in which the rolling element has a pitch circle diameter of about 50 mm (40 to 60 mm), As in the invention described in claim 4, the partial outer peripheral surface of the inner ring whose hoop stress is to be measured is present at the end of the outer peripheral surface of the inner ring adjacent to the caulking portion in the axial direction. A cylindrical surface portion is used. And the predetermined range of the said hoop stress used as the criterion of whether this caulking part is formed appropriately shall be 150-260 MPa.
When such regulation is performed, the hoop stress is set to 150 MPa or more, so that the adhesion between the shaft member and the inner ring can be sufficiently secured, and creep is generated at the fitting portion between the shaft member and the inner ring. It can be prevented from occurring. As a result, it is possible to prevent the rolling fatigue life from decreasing. Further, since the hoop stress is set to 260 MPa or less, the effect of the hoop stress acting on the inner ring raceway formed on the outer peripheral surface of the inner ring can be sufficiently suppressed. As a result, it is possible to prevent the rolling fatigue life of the bearing portion (particularly, the inner ring raceway) from decreasing.

図１〜４は、本発明の実施例１を示している。尚、本実施例の特徴は、かしめ部１４を形成した後に、このかしめ部１４が適切に形成されているか否かを判定する方法にある。対象となる車輪支持用ハブユニットの基本的な構造及び作用は、前述の図８に示した従来構造の第１例の場合と同様であるから、重複する説明を省略若しくは簡略にし、以下、本実施例の特徴部分を中心に説明する。尚、本実施例では、車輪支持用ハブユニットを構成する複列の転動体５、５のピッチ円直径を４９mmとしている。 1 to 4 show a first embodiment of the present invention. A feature of this embodiment is a method of determining whether or not the caulking portion 14 is appropriately formed after the caulking portion 14 is formed. Since the basic structure and operation of the target wheel support hub unit are the same as those in the first example of the conventional structure shown in FIG. 8 described above, the redundant description will be omitted or simplified. The description will focus on the features of the embodiment. In this embodiment, the pitch circle diameter of the double row rolling elements 5, 5 constituting the wheel supporting hub unit is set to 49 mm.

本実施例の場合、上記かしめ部１４を形成した後に、このかしめ部１４が適切に形成されているか否かを判定する為、以下の作業を行なう。
先ず、本実施例の場合には、内輪３に熱処理を施した後、この内輪３の外周面の内端部に設けた小径段部１６の外周面（特許請求の範囲に記載した「円筒面部」）に研削加工を施す。これにより、この小径段部１６の真円度を、０．１〜１．５μｍの範囲に規制する。又、これと共に、上記内輪３の内周面にも研削加工を施して、この内周面の真円度を改善する。 In the case of the present embodiment, after the caulking portion 14 is formed, the following operation is performed to determine whether or not the caulking portion 14 is appropriately formed.
First, in the case of the present embodiment, after the inner ring 3 is heat treated, the outer peripheral surface of the small-diameter step portion 16 provided at the inner end of the outer peripheral surface of the inner ring 3 (the “cylindrical surface portion described in the claims”). ]) Is ground. Thereby, the roundness of this small diameter step part 16 is controlled in the range of 0.1-1.5 micrometers. At the same time, the inner circumferential surface of the inner ring 3 is also ground to improve the roundness of the inner circumferential surface.

その後、上記内輪３をハブ２の小径段部８に圧入嵌合する前に、この内輪３の小径段部１６の外径寸法Ｄ1 を測定する。この為に、本実施例の場合には、図２に示す様に、上記小径段部１６を直径方向両側から挟む位置に１対の（接触式又は非接触式）センサ１８、１８を配置した状態で、これら１対のセンサ１８、１８により、上記小径段部１６の円周方向複数個所（例えば等間隔の２５個所）に於ける外径寸法を、上記内輪３を（例えば３０min-1 で）回転させつつ測定する｛整数回転分（例えば、１回転分）測定する｝。そして、これら各測定値の平均値を上記外径寸法Ｄ1 とする。この様な外径寸法Ｄ1 の測定作業は、上記１対のセンサ１８、１８による測定を開始してから、約１秒間で行なえる。 Then, prior to press-fitting the inner ring 3 to the cylindrical portion 8 of the hub 2, to measure the outer diameter D 1 of the cylindrical portion 16 of the inner ring 3. For this reason, in the case of this embodiment, as shown in FIG. 2, a pair of (contact or non-contact) sensors 18 and 18 are arranged at positions sandwiching the small diameter step portion 16 from both sides in the diameter direction. In this state, the pair of sensors 18 and 18 can be used to determine the outer diameter of the small-diameter step portion 16 at a plurality of circumferential locations (for example, 25 equally spaced locations) and the inner ring 3 (for example, 30 min −1) . ) Measure while rotating {Measure integer rotation (for example, one rotation)}. Then, the average value of each measured value to the outer diameter D 1. Measuring operation of such outside diameter D 1 is from the start of measurement by the sensor 18, 18 of the pair, performed in about one second.

上述の様にして外径寸法Ｄ1 を測定したならば、その後、図１（Ａ）に示す様に、車輪支持用ハブユニットを構成する各部材同士を組み立てる。この図１（Ａ）に示した状態では、上記ハブ２の内端部に未だかしめ部１４｛同図（Ｂ）参照｝は形成されていない。但し、上記内輪３を上記ハブ２の小径段部８に圧入嵌合させた事に伴い、この内輪３の小径段部１６の外径寸法は、少し（α分）だけ増大している（図３のＡ部参照）。 Once measured outer diameter D 1 in the manner described above, then, as shown in FIG. 1 (A), assembling the members that constitute the wheel support hub unit. In the state shown in FIG. 1A, the caulking portion 14 {see FIG. 1B} is not yet formed at the inner end portion of the hub 2. However, as the inner ring 3 is press-fitted into the small-diameter step portion 8 of the hub 2, the outer diameter dimension of the small-diameter step portion 16 of the inner ring 3 is slightly increased (α) (see FIG. 3 part A).

上述の図１（Ａ）に示した様に各部材同士を互いに組み立てたならば、次いで、上記ハブ２の内端部に設けた円筒部１３の先端部を、ローリングプレス加工により径方向外方に塑性変形させて、同図（Ｂ）に示す様なかしめ部１４を形成し、上記内輪３の内端面を抑え付ける。そして、この様にかしめ部１４を形成した後、上記小径段部１６の外径寸法Ｄ2 を測定する。本実施例の場合には、この外径寸法Ｄ2 の測定作業も、上述した外径寸法Ｄ1 の場合と同様にして｛図２に示す様に、上記内輪３を（上記ハブ２と共に）回転させつつ｝行なう。但し、この様な外径寸法Ｄ2 の測定作業を、実際の製造ラインで行なう場合には、次の様な問題を生じる。 If the respective members are assembled with each other as shown in FIG. 1 (A), the distal end portion of the cylindrical portion 13 provided at the inner end portion of the hub 2 is then radially outwardly moved by rolling press processing. To form a caulking portion 14 as shown in FIG. 3B, and the inner end face of the inner ring 3 is suppressed. After the formation of the caulking portions 14 in this way, to measure the outer diameter D 2 of the cylindrical portion 16. In the case of the present embodiment, this outer diameter dimension D 2 is measured in the same manner as the outer diameter dimension D 1 described above {as shown in FIG. 2, the inner ring 3 (with the hub 2). While rotating}. However, in the case where such a measurement operation of the outer diameter D 2 is performed on an actual production line, the following problems occur.

即ち、図３のＢ部に示す様に、上記内輪３の小径段部１６の外径寸法は、上記かしめ部１４を形成する事に伴って増大する。この増大量は、このかしめ部１４から上記内輪３に抑え付け力が加えられた結果生じた弾性的な増大量と、塑性加工時に発生した熱が上記かしめ部１４から上記内輪３に伝達された結果生じた熱膨張による増大量とが、互いに足し合わされたものである。このうちの熱膨張による増大量は、図３のＣ部に示す様に、時間の経過と共に徐々に減少し、十分な時間が経過した後に完全に喪失する。そして、この様に完全に喪失した後の上記小径段部１６の外径寸法が、本実施例で測定すべき外径寸法Ｄ2 となる。ところが、上記熱膨張による増大量が完全に喪失するまでには、非常に長い時間（例えば、２４時間以上）を要す。この為、この様な非常に長い時間を経過した後に上記外径寸法Ｄ2 を測定する方法を採用すると、実際の製造ラインでは、作業能率が著しく低下する。 That is, as shown in part B of FIG. 3, the outer diameter of the small diameter step part 16 of the inner ring 3 increases as the caulking part 14 is formed. The amount of increase is the amount of elastic increase generated as a result of the pressing force applied from the caulking portion 14 to the inner ring 3 and the heat generated during the plastic working is transmitted from the caulking portion 14 to the inner ring 3. The resulting increase in thermal expansion is the sum of each other. Of these, the increase due to thermal expansion gradually decreases with time as shown in part C of FIG. 3, and is completely lost after a sufficient time has elapsed. The outer diameter of the cylindrical portion 16 after completely lost in this manner becomes the outer diameter D 2 to be measured in this embodiment. However, it takes a very long time (for example, 24 hours or more) until the increase due to the thermal expansion is completely lost. Therefore, when adopting the method of measuring the outer diameter dimension D 2 after a lapse of such a very long time, in an actual production line, the working efficiency is remarkably lowered.

そこで、本実施例では、図３に示す様に、上記かしめ部１４を形成した後、直ちに（上記熱膨張による増大量が完全に喪失する前に）上記小径段部１６の外径寸法を測定する。そして、この様に測定した外径寸法から上記熱膨張による増大量を引いた値を、上記外径寸法Ｄ2 とする。尚、この熱膨張による増大量は、上記かしめ部１４を形成してからの経過時間（更にはハブユニットの仕様や周囲温度）によって変化する。この為、本実施例の場合には、予め、複数の試料（ワーク）を用いて、実際の製造工程に即した条件下で実験を行ない、図４に示す様な、熱膨張による増大量に関する予測テーブルを作成しておく。そして、この予測テーブルを用いて、上記小径段部１６の外径寸法を測定した時刻に於ける、熱膨張による増大量を決定する（例えば、上記かしめ部１４を形成してから７０sec 後に測定した場合には、熱膨張による増大量を５μm と決定する）。 Therefore, in this embodiment, as shown in FIG. 3, the outer diameter of the small-diameter step portion 16 is measured immediately after the caulking portion 14 is formed (before the increase due to the thermal expansion is completely lost). To do. Then, a value obtained by subtracting the increased amount due to the thermal expansion from the outer diameter measured in this way, and the outer diameter dimension D 2. Note that the amount of increase due to the thermal expansion varies depending on the elapsed time after the formation of the caulking portion 14 (and the specifications of the hub unit and the ambient temperature). For this reason, in the case of the present embodiment, an experiment is performed in advance using a plurality of samples (workpieces) under conditions that are in accordance with the actual manufacturing process, and as shown in FIG. Create a prediction table. Then, using this prediction table, the amount of increase due to thermal expansion at the time when the outer diameter of the small diameter step portion 16 is measured is determined (for example, measured 70 seconds after the formation of the caulking portion 14). In this case, the increase due to thermal expansion is determined to be 5 μm).

上述の様にして各外径寸法Ｄ1 、Ｄ2 を測定したならば、次いで、これら各外径寸法Ｄ1 、Ｄ2 と、上記内輪３のヤング率（弾性係数）Ｅとに基づいて、次の（１）式を計算する事により、上記かしめ部１４を形成した後に上記小径段部１６の表面で発生しているフープ応力σh を求める。
σh ＝Ｅ×（Ｄ2 −Ｄ1 ）／Ｄ1 −−−−−−（１）
そして、このフープ応力σh の値が、１５０〜２６０ＭＰａの範囲に収まっている場合にのみ、上記かしめ部１４が適切に形成されていると判定する。 If the outer diameters D 1 and D 2 are measured as described above, then, based on these outer diameters D 1 and D 2 and the Young's modulus (elastic coefficient) E of the inner ring 3, By calculating the following equation (1), the hoop stress σ h generated on the surface of the small diameter step portion 16 after the formation of the caulking portion 14 is obtained.
σ h = E × (D 2 -D 1) / D 1 ------ (1)
And only when the value of the hoop stress σ h is in the range of 150 to 260 MPa, it is determined that the caulking portion 14 is appropriately formed.

上述の様に、本実施例の車輪支持用ハブユニットの製造方法の場合には、内輪３の外周面の内端部に設けた小径段部１６に発生しているフープ応力σh の値に基づいて、かしめ部１４が適切に形成されているか否かを判定する。従って、転がり疲れ寿命に関する信頼性の高い製品のみを出荷できる。 As described above, in the case of the wheel support hub unit manufacturing method according to the present embodiment, the value of the hoop stress σ h generated in the small diameter step portion 16 provided at the inner end portion of the outer peripheral surface of the inner ring 3 is set. Based on this, it is determined whether or not the caulking portion 14 is appropriately formed. Therefore, only reliable products relating to rolling fatigue life can be shipped.

即ち、本実施例の場合、上記かしめ部１４が適切に形成されていると判定される車輪支持用ハブユニットは、上記フープ応力σh の値が１５０ＭＰａ以上である。この為、ハブ２と上記内輪３との密着性を十分に確保する事ができ、これらハブ２と内輪３との嵌合部でクリープが発生する事を防止できる。この結果、転がり疲れ寿命が低下する事を防止できる。又、上記フープ応力σh の値が２６０ＭＰａ以下である為、上記内輪３の外周面に形成された第二の内輪軌道７ｂに作用するフープ応力の影響を十分に抑える事ができる。この結果、転がり疲れ寿命が低下する事を防止できる。 That is, in the present embodiment, the wheel support hub unit in which it is determined that the caulking portion 14 is appropriately formed has a hoop stress σ h value of 150 MPa or more. For this reason, sufficient adhesion between the hub 2 and the inner ring 3 can be ensured, and the occurrence of creep at the fitting portion between the hub 2 and the inner ring 3 can be prevented. As a result, it is possible to prevent the rolling fatigue life from decreasing. Further, since the value of the hoop stress σ h is 260 MPa or less, the influence of the hoop stress acting on the second inner ring raceway 7b formed on the outer peripheral surface of the inner ring 3 can be sufficiently suppressed. As a result, it is possible to prevent the rolling fatigue life from decreasing.

又、本実施例の場合には、上記小径段部１６の外周面のフープ応力σh を、上記小径段部１６の外径寸法Ｄ1 、Ｄ2 を測定する事に基づいて求める。従って、例えば、このフープ応力σh の測定作業を、上記小径段部１６の外周面に歪みゲージを添着して測定する場合に比べて容易にできる。 In the case of this embodiment, the hoop stress σ h of the outer peripheral surface of the small diameter step portion 16 is obtained based on measuring the outer diameter dimensions D 1 and D 2 of the small diameter step portion 16. Therefore, for example, the measurement operation of the hoop stress σ h can be facilitated as compared with the case where the strain gauge is attached to the outer peripheral surface of the small diameter step portion 16 and measured.

更に、本実施例の場合には、上記内輪３の熱処理を行なった後、上記小径段部１６の外径寸法Ｄ1 、Ｄ2 を測定する前に、この小径段部１６に研削加工を施して、この小径段部１６の真円度を改善している（この真円度を０．１〜１．５μｍの範囲の値としている）。特に、本実施例の場合には、この真円度が１．５μｍ以下である為、上記フープ応力σh （上記各外径寸法Ｄ1 、Ｄ2 ）の測定精度を十分に高める事ができる。又、本実施例の場合には、上記熱処理後、上記内輪３の内周面に研削加工を施して、この内周面の真円度を改善している。この為、この内輪３と上記ハブ２の小径段部８との嵌め合いを良くする事ができる。従って、この様な措置も、上記フープ応力σh （上記外径寸法Ｄ2 ）の測定精度の向上に寄与し得る。この結果、転がり疲れ寿命に関する信頼性を十分に向上させる事ができる。又、上記真円度が０．１μｍ以上である為、上記研削加工のコストを抑える事ができる。 Further, in the case of this embodiment, after the heat treatment of the inner ring 3 and before measuring the outer diameter dimensions D 1 and D 2 of the small diameter step portion 16, the small diameter step portion 16 is ground. Thus, the roundness of the small-diameter step portion 16 is improved (this roundness is set to a value in the range of 0.1 to 1.5 μm). In particular, in the case of the present embodiment, since the roundness is 1.5 μm or less, the measurement accuracy of the hoop stress σ h (the respective outer diameter dimensions D 1 and D 2 ) can be sufficiently increased. . In the case of this embodiment, after the heat treatment, the inner peripheral surface of the inner ring 3 is ground to improve the roundness of the inner peripheral surface. For this reason, the fitting between the inner ring 3 and the small-diameter step portion 8 of the hub 2 can be improved. Therefore, such a measure can also contribute to the improvement of the measurement accuracy of the hoop stress σ h (the outer diameter D 2 ). As a result, the reliability related to the rolling fatigue life can be sufficiently improved. Further, since the roundness is 0.1 μm or more, the cost of the grinding process can be suppressed.

次に、本発明の効果を確かめる為に行なった実験に就いて説明する。本実験では、試料となる車輪支持用ハブユニットとして、上述の図１に示した実施例１と同様の構造のものを採用した。即ち、内輪３及び外輪４の材料として、炭素を０．５０〜０．６０重量％含有する鋼を用い、各転動体５、５の材料として軸受鋼（ＳＵＪ２）を用い、保持器の材料として合成樹脂を用いた。又、上記各転動体５、５のピッチ円直径を４９mmとした。又、上記内輪３には、表面から心部にまで熱処理を施した後、この内輪３の小径段部１６に研削加工を施して、この小径段部１６の真円度を改善した。   Next, an experiment conducted to confirm the effect of the present invention will be described. In this experiment, a wheel support hub unit as a sample having the same structure as that of Example 1 shown in FIG. That is, as the material of the inner ring 3 and the outer ring 4, steel containing 0.50 to 0.60% by weight of carbon is used, bearing steel (SUJ2) is used as the material of the rolling elements 5, 5, and the cage material is used. A synthetic resin was used. Further, the pitch circle diameter of each of the rolling elements 5 and 5 was set to 49 mm. Further, the inner ring 3 was subjected to a heat treatment from the surface to the core, and then the small diameter step portion 16 of the inner ring 3 was ground to improve the roundness of the small diameter step portion 16.

そして、本実験では、上記小径段部１６の真円度と、かしめ部１４を形成する際のかしめ荷重とのうちの、少なくとも１つの要素が互いに異なる、１３種類の試料を用意した。これら１３種類の試料を、以下の表１に示す。

Figure 0004278542
In this experiment, 13 types of samples were prepared in which at least one of the roundness of the small-diameter step portion 16 and the caulking load when forming the caulking portion 14 was different. These 13 types of samples are shown in Table 1 below.
Figure 0004278542

本実験では、上記１３種類の試料毎にそれぞれ、上述した実施例１の場合と同様の方法により、上記内輪３を上記ハブ２の小径段部８に圧入嵌合させる前と、上記かしめ部１４を形成した後とで、それぞれ上記小径段部１６の外径寸法Ｄ1 、Ｄ2 を測定した。これと共に、これら各外径寸法Ｄ1 、Ｄ2 と上記内輪３のヤング率Ｅとに基づいて前記（１）式により、上記かしめ部１４の形成後に上記小径段部１６の表面で発生してるフープ応力σh を算出した。この算出結果を、上記表１中の「外径寸法から算出したフープ応力」の欄に示す。又、これと同時に、上記かしめ部１４を形成する際に上記小径段部１６に歪みゲージを添着し、この歪みゲージにより、上記かしめ部１４の形成後に上記小径段部１６の外周面で発生しているフープ応力σh （熱膨張による影響が喪失した状態でのフープ応力）を測定した。この測定結果を、上記表１中の「歪みゲージから測定したフープ応力」の欄に示す。尚、上記歪みゲージは、上記小径段部１６の円周方向等間隔の４個所に添着し、これら４個所から測定されるフープ応力σh の平均値を、上記表１中に記載した。又、上記１３種類の試料毎にそれぞれ、「フープ応力比」（＝「外径寸法から算出したフープ応力」÷「歪みゲージから測定したフープ応力」）を計算した。この計算結果を、上記表１及び図５に示す。 In this experiment, for each of the 13 types of samples, the inner ring 3 was press-fitted into the small-diameter step portion 8 of the hub 2 and the caulking portion 14 by the same method as in the first embodiment. The outer diameters D 1 and D 2 of the small-diameter step portion 16 were measured after and after forming, respectively. At the same time, it is generated on the surface of the small-diameter step portion 16 after the formation of the caulking portion 14 according to the equation (1) based on the outer diameter dimensions D 1 and D 2 and the Young's modulus E of the inner ring 3. The hoop stress σ h was calculated. This calculation result is shown in the column of “Hoop stress calculated from outer diameter” in Table 1 above. At the same time, when the caulking portion 14 is formed, a strain gauge is attached to the small diameter step portion 16, and this strain gauge generates the outer diameter surface of the small diameter step portion 16 after the caulking portion 14 is formed. Hoop stress σ h (hoop stress in a state where the influence of thermal expansion is lost) was measured. The measurement results are shown in the column “Hoop stress measured from strain gauge” in Table 1 above. The strain gauges were attached to four locations at equal intervals in the circumferential direction of the small-diameter step portion 16, and the average value of the hoop stress σ h measured from these four locations is shown in Table 1 above. Further, for each of the 13 types of samples, “hoop stress ratio” (= “hoop stress calculated from outer diameter” ÷ “hoop stress measured from strain gauge”) was calculated. The calculation results are shown in Table 1 and FIG.

上記表１及び図５に示した結果から明らかな様に、上記小径段部１６の真円度が１．５μｍ以下である各試料１〜１０は、同じく１．５μｍよりも大きい各試料１１〜１３に比べて、「フープ応力比」が１に対して十分に近い値となっている。即ち、請求項３に記載した発明の様に、上記小径段部１６の真円度を１．５μｍ以下とすれば、「外径寸法から算出したフープ応力」を「歪みゲージから測定したフープ応力」に対して十分に近づける事ができ、結果として信頼性の高い転がり疲れ寿命の管理を行なえる事が分る。 As is clear from the results shown in Table 1 and FIG. 5, the samples 1 to 10 in which the roundness of the small-diameter step portion 16 is 1.5 μm or less are the same as the samples 11 to 11 that are also larger than 1.5 μm. Compared to 13, the “hoop stress ratio” is sufficiently close to 1. That is, as in the invention described in claim 3 , if the roundness of the small diameter step portion 16 is 1.5 μm or less, the “hoop stress calculated from the outer diameter dimension” is “the hoop stress measured from the strain gauge”. As a result, it can be seen that the rolling fatigue life can be managed with high reliability.

次に、上記各試料１〜１０に就いて、以下の条件で回転試験を行なった（前記外輪４を固定し、前記ハブ２及び内輪３を回転させた）。
回転速度 ： １，０００min-1
ラジアル荷重 ： ６，５００Ｎ
アキシアル荷重 ： ３，９００Ｎ
そして、上記各試料１〜１０の転がり疲れ寿命を測定した。この測定結果を、以下の表２、及び図６に示す。尚、これら表２及び図６では、上記各試料１〜１０の転がり疲れ寿命を、試料１の転がり疲れ寿命の値を１．０とした場合の相対値（「転がり疲れ寿命比」）で示している。

Figure 0004278542
Next, a rotation test was performed on each of the above samples 1 to 10 under the following conditions (the outer ring 4 was fixed and the hub 2 and the inner ring 3 were rotated).
Rotational speed: 1,000min -1
Radial load: 6,500N
Axial load: 3,900N
And the rolling fatigue life of each said samples 1-10 was measured. The measurement results are shown in Table 2 below and FIG. In Table 2 and FIG. 6, the rolling fatigue life of each of the above samples 1 to 10 is shown as a relative value (“rolling fatigue life ratio”) when the value of the rolling fatigue life of sample 1 is 1.0. ing.
Figure 0004278542

上述した回転試験後の各試料１〜１０を観察し、更に分析したところ、「外径寸法から算出したフープ応力」が１５０ＭＰａよりも小さい各試料１、８は、上記ハブ２と上記内輪３との密着性が不十分であった為に、これらハブ２と内輪３との嵌合部でクリープが生じた結果、転がり疲れ寿命が短くなった事が分った。又、「外径寸法から算出したフープ応力」が２６０ＭＰａよりも大きい各試料５、６は、上記内輪３の外周面に形成された第二の内輪軌道７ｂに作用する、上記フープ応力の影響を十分に抑える事ができなかった為に、転がり疲れ寿命が短くなった事が分った。これに対し、請求項４に記載した発明の様に、「外径寸法から算出したフープ応力」が１５０〜２６０ＭＰａの範囲に収まっている各試料２、３、４、７、９、１０は、上記各試料１、８、５、６で生じた様な不具合が生じなかった為に、長寿命を得られた事が分った。 When each of the samples 1 to 10 after the rotation test described above was observed and further analyzed, each of the samples 1 and 8 having a “hoop stress calculated from the outer diameter” of less than 150 MPa was the hub 2 and the inner ring 3. It was found that the rolling fatigue life was shortened as a result of creep occurring at the fitting portion between the hub 2 and the inner ring 3 due to the insufficient adhesion. Further, each of the samples 5 and 6 having a “hoop stress calculated from the outer diameter dimension” larger than 260 MPa has an effect of the hoop stress acting on the second inner ring raceway 7b formed on the outer peripheral surface of the inner ring 3. It was found that the rolling fatigue life was shortened because it could not be suppressed sufficiently. On the other hand, as in the invention described in claim 4 , each sample 2, 3, 4 , 7 , 9, 10 in which the “hoop stress calculated from the outer diameter” is in the range of 150 to 260 MPa is as follows: It was found that a long life could be obtained because no problems such as those caused by the samples 1, 8, 5, and 6 occurred.

尚、本発明を実施する場合には、図７（Ａ）に示す様な工程順を採用する事もできる。この図７（Ａ）に示した工程は、上述の実施例１で採用した工程とほぼ同様であるが、内輪の一部外周面（上述の実施例１では小径段部１６）の外径寸法測定を、３回行なう点で異なる。このうち、上述の実施例１では行なわなかった外径寸法測定（２）は、内輪をハブの小径段部に圧入した時点で発生しているフープ応力を確認する為に行なう。この様な外径寸法測定（２）は、かしめ部の形成管理の慎重を期す上で、好ましい作業であると言えるが、上述した実施例１の場合の様に省略しても、特に問題が生じる事はない。一方、図７（Ｂ）に示した工程は、上述の実施例１の場合とは異なり、内輪の一部外周面の研削を、この内輪をハブの小径段部に圧入した後に行なう。これと共に、図示の各工程間で、それぞれ内輪の一部外周面の外径寸法測定（１）〜（４）を行なう。この様な図７（Ｂ）に示した工程では、内輪をハブの小径段部に圧入する事に基づいて生じた、この内輪の一部外周面の膨張量が、円周方向に関して不均一になった場合でも、その後、この一部外周面を研削する事により、当該不均一を解消できる（この一部外周面の真円度を改善できる）。この為、この一部外周面で発生している純粋なフープ応力を求める事ができ、かしめ部の形成管理の信頼性を向上できる。この様な図７（Ｂ）に示した工程は、本発明の技術的範囲から外れる。 When the present invention is carried out, the order of steps as shown in FIG. 7A can be adopted. The process shown in FIG. 7A is substantially the same as the process employed in the above-described first embodiment, but the outer diameter of a part of the outer peripheral surface of the inner ring (small-diameter step portion 16 in the above-described first embodiment). The difference is that the measurement is performed three times. Among these, the outer diameter dimension measurement (2) not performed in the above-described first embodiment is performed in order to confirm the hoop stress generated when the inner ring is press-fitted into the small-diameter step portion of the hub. Such outer diameter dimension measurement (2) can be said to be a preferable operation for careful control of the formation of the caulking portion, but there is a particular problem even if it is omitted as in Example 1 described above. It never happens. On the other hand, unlike the case of the first embodiment, the process shown in FIG. 7B is performed after the inner ring is pressed into the small-diameter step portion of the hub. At the same time, the outer diameter measurements (1) to (4) of a part of the outer peripheral surface of the inner ring are performed between the illustrated steps. In the process shown in FIG. 7B, the expansion amount of a part of the outer peripheral surface of the inner ring that is generated by press-fitting the inner ring into the small-diameter step portion of the hub is uneven in the circumferential direction. Even in this case, the non-uniformity can be eliminated by grinding the partial outer peripheral surface (the roundness of the partial outer peripheral surface can be improved). For this reason, the pure hoop stress generated on the partial outer peripheral surface can be obtained, and the formation management reliability of the caulking portion can be improved. Such a process shown in FIG. 7B is out of the technical scope of the present invention.

又、本発明は、上述の実施例１に示した車輪支持用ハブユニットに限らず、軸部材の一端部に内輪を抑え付ける為のかしめ部を形成する総ての車輪支持用ハブユニットに対して適用できる。この場合に、例えば、前記図９〜１０に示した構造の様に、内輪３ａの外周面の内端部に小径段部が存在しない場合には、この内輪３ａの肩部１５の外周面のフープ応力（外径寸法）を測定する。尚、この場合に、シールリングが測定の邪魔になる場合には、このシールリングは、当該測定後に組み付ける様にする。又、かしめ部の形成後に内輪の一部外周面で発生しているフープ応力の好ましい範囲（各転動体のピッチ円直径が５０mm程度の車輪支持用ハブユニットの場合には、請求項４に記載した様に、１５０〜２６０ＭＰａの範囲）は、対象となる車輪支持用ハブユニットを構成する各転動体のピッチ円直径に応じて多少変化する。従って、このピッチ円直径が５０mmよりも大幅に（例えば１０mmを越えて）小さい（ピッチ円直径が４０mm未満）或は大きい（ピッチ円直径が６０mmを越える）車輪支持用ハブユニットを対象とする場合には、予め実験等により上記フープ応力の好ましい範囲を調べておいてから、本発明を実施する。 Further, the present invention is not limited to the wheel support hub unit shown in the first embodiment, but is applicable to all wheel support hub units that form a caulking portion for holding the inner ring at one end of the shaft member. Can be applied. In this case, for example, as in the structure shown in FIGS. 9 to 10, when there is no small diameter step at the inner end of the outer peripheral surface of the inner ring 3a, the outer peripheral surface of the shoulder 15 of the inner ring 3a Measure hoop stress (outer diameter). In this case, if the seal ring interferes with the measurement, the seal ring is assembled after the measurement. Further, a preferable range of hoop stress generated on the outer peripheral surface of a part of the inner ring after the formation of the caulking portion (in the case of a wheel support hub unit in which each rolling element has a pitch circle diameter of about 50 mm, it is described in claim 4 . As described above, the range of 150 to 260 MPa slightly changes depending on the pitch circle diameter of each rolling element constituting the wheel support hub unit. Accordingly, when the wheel support hub unit has a pitch circle diameter significantly smaller than 50 mm (for example, more than 10 mm) (pitch circle diameter is less than 40 mm) or larger (pitch circle diameter is more than 60 mm). First, a preferred range of the hoop stress is examined in advance by experiments or the like, and then the present invention is carried out.

本発明の実施例１を示しており、（Ａ）はかしめ部を形成する前の状態を、（Ｂ）は同じく形成した後の状態を、それぞれ示す断面図。FIGS. 2A and 2B show a first embodiment of the present invention, in which FIG. 1A is a sectional view showing a state before a caulking portion is formed, and FIG. 内輪の小径段部の外径寸法を測定する状況を示す図。The figure which shows the condition which measures the outer diameter dimension of the small diameter step part of an inner ring | wheel. 内輪の小径段部の外径寸法が各工程毎に変化する様子を示す図。The figure which shows a mode that the outer diameter dimension of the small diameter step part of an inner ring changes for every process. 実験により求めた、熱膨張による増大量に関する予測テーブルを示す図。The figure which shows the prediction table regarding the increase amount by thermal expansion calculated | required by experiment. フープ応力比と真円度との関係を示す図。The figure which shows the relationship between hoop stress ratio and roundness. 転がり疲れ寿命比とフープ応力との関係を示す図。The figure which shows the relationship between rolling fatigue life ratio and hoop stress. 本発明を実施する場合に採用しうる製造工程の２例を示すブロック図。The block diagram which shows two examples of the manufacturing process which can be employ | adopted when implementing this invention. 本発明の対象となる車輪支持用ハブユニットの第１例を示す断面図。Sectional drawing which shows the 1st example of the hub unit for wheel support used as the object of this invention. 同第２例を示す断面図。Sectional drawing which shows the 2nd example. 同第３例を示す断面図。Sectional drawing which shows the 3rd example.

符号の説明Explanation of symbols

１、１ａ、１ｂ 車輪支持用ハブユニット
２、２ａ ハブ
３、３ａ 内輪
４、４ａ 外輪
５ 転動体
６ 取付フランジ
７ａ、７ｂ 内輪軌道
８ 小径段部
９ 段差面
１０ スプライン孔
１１ 結合フランジ
１２ａ、１２ｂ 外輪軌道
１３ 円筒部
１４ かしめ部
１５ 肩部
１６ 小径段部
１７ 軸部材
１８ センサ
DESCRIPTION OF SYMBOLS 1, 1a, 1b Wheel support hub unit 2, 2a Hub 3, 3a Inner ring 4, 4a Outer ring 5 Rolling element 6 Mounting flange 7a, 7b Inner ring raceway 8 Small diameter step 9 Step surface 10 Spline hole 11 Joint flange 12a, 12b Outer ring Track 13 Cylindrical part 14 Caulking part 15 Shoulder part 16 Small diameter step part 17 Shaft member 18 Sensor

Claims (4)

軸部材の一端部に設けた小径段部に内輪を外嵌すると共に、この内輪の一端面を、この軸部材の一端部に設けた円筒部のうちこの内輪の一端面から突出した部分を径方向外方に塑性変形させて形成したかしめ部により抑え付ける事で、上記内輪を上記軸部材に結合固定している車輪支持用ハブユニットの製造方法であって、熱処理を施した後に一部外周面に研削加工を施してこの一部外周面の真円度を改善した内輪を上記小径段部に外嵌し、次いで、上記かしめ部を形成した後に、この内輪の一部外周面で発生している円周方向の引っ張り応力を、この内輪の一部外周面で上記真円度を改善した部分の外径寸法を、この内輪を上記小径段部に外嵌する前と、上記かしめ部を形成した後とでそれぞれ測定する事により測定し、この引っ張り応力の値が所定範囲に収まっている場合にのみ上記かしめ部が適切に形成されていると判定する為、このかしめ部を形成する事に伴って生じた熱により上記内輪が熱膨張したままの状態でこの内輪の一部外周面で上記真円度を改善した部分の外径寸法を測定すると共に、当該測定時の熱膨張に基づく外径寸法の増大量を予め用意しておいた実験データに基づいて推定し、上記測定した外径寸法からこの推定した増大量を差し引いた値を、上記かしめ部を形成した後の上記内輪の一部外周面で上記真円度を改善した部分の外径寸法とする車輪支持用ハブユニットの製造方法。 The inner ring is externally fitted to a small-diameter step provided at one end of the shaft member, and one end surface of the inner ring is formed from a portion of the cylindrical portion provided at one end of the shaft member that protrudes from one end surface of the inner ring. A hub unit for supporting a wheel in which the inner ring is coupled and fixed to the shaft member by being restrained by a caulking portion formed by plastic deformation outward in a direction, and a part of outer periphery after heat treatment An inner ring whose surface has been ground to improve the roundness of the outer peripheral surface is externally fitted to the small-diameter stepped portion, and then the caulking portion is formed, and then generated on the outer peripheral surface of the inner ring. The circumferential tensile stress of the inner ring, the outer diameter of the part of the inner ring where the roundness is improved, the outer diameter of the part where the inner ring is externally fitted to the small diameter step, and the caulking part This tensile stress is measured by measuring each after and after forming. Because determines that the crimped portion only if the value is within the predetermined range is properly formed, the heat generated in association with that forming the crimped portion in a state where the inner ring is thermally expanded Based on the experimental data prepared in advance for the outer diameter of the portion of the inner ring where the roundness has been improved on the outer peripheral surface of the inner ring and the amount of increase in the outer diameter based on the thermal expansion during the measurement. The value obtained by subtracting the estimated increase amount from the measured outer diameter dimension is the outer diameter dimension of the portion where the roundness is improved on the partial outer peripheral surface of the inner ring after the caulking portion is formed. A method for manufacturing a wheel-supporting hub unit. 内輪の一部外周面の外径寸法を、この内輪を小径段部に外嵌する前と、かしめ部を形成した後とでそれぞれ測定すると共に、これら各外径寸法の測定値と上記内輪の弾性係数とに基づく応力の計算を行なう事により、上記円周方向の引っ張り応力を管理する、請求項１に記載した車輪支持用ハブユニットの製造方法。   The outer diameter of a part of the outer peripheral surface of the inner ring is measured before the inner ring is fitted on the small-diameter step portion and after the caulking portion is formed, and the measured values of the outer diameter dimensions and the inner ring are measured. The wheel support hub unit manufacturing method according to claim 1, wherein the tensile stress in the circumferential direction is managed by calculating a stress based on an elastic coefficient. 研削加工を施した後の内輪の一部外周面の真円度を０．１〜１．５μｍの範囲に規制する、請求項１〜２のうちの何れか１項に記載した車輪支持用ハブユニットの製造方法。   The wheel support hub according to any one of claims 1 to 2, wherein the roundness of a part of the outer peripheral surface of the inner ring after grinding is restricted to a range of 0.1 to 1.5 µm. Unit manufacturing method. 円周方向の引っ張り応力を測定すべき内輪の一部外周面が、この内輪の外周面のうち、軸方向に関してかしめ部と隣接する側の端部に存在する円筒面部であり、このかしめ部が適切に形成されているか否かの判定基準となる上記引っ張り応力の所定範囲が１５０〜２６０ＭＰａである、請求項１〜３のうちの何れか１項に記載した車輪支持用ハブユニットの製造方法。   A part of the outer peripheral surface of the inner ring whose tensile stress in the circumferential direction is to be measured is a cylindrical surface part that is present at an end of the inner ring adjacent to the caulking part with respect to the axial direction. The method for manufacturing a wheel-supporting hub unit according to any one of claims 1 to 3, wherein a predetermined range of the tensile stress, which is a criterion for determining whether or not it is properly formed, is 150 to 260 MPa.
JP2004078809A 2004-03-12 2004-03-18 Manufacturing method of wheel supporting hub unit Expired - Fee Related JP4278542B2 (en)

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