JP2005145313A - Rolling bearing unit for supporting vehicle wheel - Google Patents

Rolling bearing unit for supporting vehicle wheel Download PDF

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Publication number
JP2005145313A
JP2005145313A JP2003387475A JP2003387475A JP2005145313A JP 2005145313 A JP2005145313 A JP 2005145313A JP 2003387475 A JP2003387475 A JP 2003387475A JP 2003387475 A JP2003387475 A JP 2003387475A JP 2005145313 A JP2005145313 A JP 2005145313A
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Japan
Prior art keywords
wheel
rolling bearing
bearing unit
recessed portion
hub
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JP2003387475A
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Japanese (ja)
Inventor
Yuji Miyamoto
祐司 宮本
Hideyuki Uyama
英幸 宇山
Susumu Tanaka
進 田中
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NSK Ltd
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NSK Ltd
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Priority to JP2003387475A priority Critical patent/JP2005145313A/en
Publication of JP2005145313A publication Critical patent/JP2005145313A/en
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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
    • F16C33/64—Special methods of manufacture
    • 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)
  • Manufacturing & Machinery (AREA)
  • Mechanical Engineering (AREA)
  • Rolling Contact Bearings (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a rolling bearing unit 1 for supporting a vehicle wheel structured so that its flange 6 and a recessed part 11b are made thin for reducing the weight, capable of accomplishing a structure unlikely to generate a breakage of the recessed part 11b even in case that the root part of the flange 6 is given a higher strength. <P>SOLUTION: The recessed part 11b is subjected to a turning process, and a decarbonized layer is removed from the surface of the recessed part 11b, wherein the surface roughness is made 25 μmR<SB>av</SB>or less. A hardened layer 16 is formed at the recessed part 11b after the turning process, which can enhance the fatigue strength of the recessed part 11b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

本発明は、自動車の車輪を懸架装置に対し回転自在に支持する為の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 in a rolling bearing unit for supporting a wheel for rotatably supporting a wheel of an automobile with respect to a suspension device.

自動車の車輪を懸架装置に対し回転自在に支持する為に、例えば図４に示す様な車輪支持用転がり軸受ユニット１が広く使用されている。この図４に示した車輪支持用転がり軸受ユニット１は、ハブ輪２と、内輪３と、外輪４と、複数個の転動体５、５（玉）とを備える。このうちのハブ輪２の外周面の外端部（軸方向に関して外とは、自動車への組み付け状態で幅方向外寄りとなる側を言い、図１、２、４、５の左側。反対に幅方向中央寄りとなる側を、軸方向に関する内と言い、図１、２、４、５の右側。本明細書及び特許請求の範囲全体で同じ。）には、車輪を支持する為のフランジ６を形成している。又、このハブ輪２の中間部外周面には第一の内輪軌道７ａ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、この段部８に、外周面に第二の内輪軌道７ｂを形成した、上記内輪３を外嵌している。又、この内輪３の内端面は、上記ハブ輪２の内端部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９により抑え付けて、上記内輪３を上記ハブ輪２の所定位置に固定している。又、上記外輪４の内周面には複列の外輪軌道１０、１０を形成し、これら両外輪軌道１０、１０と上記両内輪軌道７ａ、７ｂとの間に上記各転動体５、５を、それぞれ複数個ずつ設けている。尚、重量が嵩む自動車用の車輪支持用転がり軸受ユニットの場合、上記各転動体５、５としてテーパころを使用する場合もある。   In order to rotatably support the wheels of an automobile with respect to a suspension device, for example, a wheel bearing rolling bearing unit 1 as shown in FIG. 4 is widely used. The wheel-supporting rolling bearing unit 1 shown in FIG. 4 includes a hub ring 2, an inner ring 3, an outer ring 4, and a plurality of rolling elements 5, 5 (balls). Of these, the outer end of the outer peripheral surface of the hub wheel 2 (outside with respect to the axial direction means the side that is outward in the width direction when assembled to the automobile, and is the left side of FIGS. The side closer to the center in the width direction is referred to as the inner side in the axial direction, and is the right side of FIGS. 1, 2, 4, and 5 (the same applies to the entire specification and claims). 6 is formed. A first inner ring raceway 7a is formed on the outer peripheral surface of the intermediate part of the hub wheel 2, and a step part 8 having a smaller outer diameter is formed on the inner end part. And the said inner ring | wheel 3 which formed the 2nd inner ring track | orbit 7b in the outer peripheral surface at this step part 8 is externally fitted. Further, the inner end surface of the inner ring 3 is suppressed by a caulking portion 9 formed by caulking and expanding the cylindrical portion formed at the inner end portion of the hub wheel 2 in the diametrically outward direction. 2 is fixed at a predetermined position. Further, double-row outer ring raceways 10 and 10 are formed on the inner peripheral surface of the outer ring 4, and the rolling elements 5 and 5 are placed between the outer ring raceways 10 and 10 and the inner ring raceways 7a and 7b. A plurality of each is provided. In addition, in the case of a rolling bearing unit for supporting a wheel for an automobile that is heavy, tapered rollers may be used as the rolling elements 5 and 5.

又、上記ハブ輪２の外端面を軸方向内方に凹ませて凹入部１１を形成している。即ち、このハブ輪２の外端部で上記フランジ６の径方向内側に、このフランジ６の外端面よりも軸方向外方に突出した状態で円筒部１８を形成している。そして、この円筒部１８の径方向内側部分を軸方向内方に凹ませて、断面略半円形状の上記凹入部１１を形成している。尚、この凹入部１１の形状は、図示の例に限らない。例えば、後述する図５に示す様な形状とする場合もある。又、上記円筒部１８は、外周面に、ドラムやディスク等の制動用回転体及び車輪を支持する為に設けている。この様に、上記ハブ輪２の外端部に凹入部１１を設ける事により、上記車輪支持用転がり軸受ユニット１の軽量化を図れる。又、上記内輪３を上記ハブ輪２に外嵌する作業を容易にする事ができる。即ち、上記凹入部１１に治具等の支持部材を挿入してこのハブ輪２の外端側を支持できる為、上記内輪３の外嵌作業を容易にする事ができる。更に、鍛造時の上記フランジ６の張り出し成形作業を容易にする事ができる。   Further, the outer end surface of the hub wheel 2 is recessed inward in the axial direction to form a recessed portion 11. That is, a cylindrical portion 18 is formed at the outer end portion of the hub wheel 2 on the radially inner side of the flange 6 so as to protrude outward in the axial direction from the outer end surface of the flange 6. Then, the radially inner portion of the cylindrical portion 18 is recessed inward in the axial direction to form the recessed portion 11 having a substantially semicircular cross section. In addition, the shape of this recessed part 11 is not restricted to the example of illustration. For example, it may have a shape as shown in FIG. The cylindrical portion 18 is provided on the outer peripheral surface to support a braking rotator such as a drum or a disk and a wheel. In this manner, by providing the recessed portion 11 at the outer end of the hub wheel 2, the wheel support rolling bearing unit 1 can be reduced in weight. Further, the work of fitting the inner ring 3 to the hub ring 2 can be facilitated. That is, since a support member such as a jig can be inserted into the recessed portion 11 to support the outer end side of the hub wheel 2, the outer fitting operation of the inner ring 3 can be facilitated. Furthermore, the overhanging operation of the flange 6 during forging can be facilitated.

尚、上述した構造は、従動輪（ＦＦ車の後輪、ＦＲ、ＭＲ、ＲＲ車の前輪）用の車輪支持用転がり軸受ユニット１に就いて示しているが、図５に示す様に、ハブ輪２ａの中心部を軸方向に貫通した通孔に、車輪用等速ジョイント１２のスプライン軸１３を挿通する為の、雌スプライン１４を形成した駆動輪（ＦＦ車の前輪、ＦＲ、ＭＲ、ＲＲ車の後輪、４ＷＤ車の全輪）用の車輪支持用転がり軸受ユニット１ａの場合、上記ハブ輪２ａの外端面に凹入部１１ａを設ける事により、上記車輪用等速ジョイント１２の組み付け性（スプライン軸１３の先端部に螺合したナットの締め付け作業性）を良好にできる。   The structure described above is shown for the wheel support rolling bearing unit 1 for the driven wheel (rear wheel of FF vehicle, FR, MR, front wheel of RR vehicle). However, as shown in FIG. Driving wheels (front wheels of FF vehicles, FR, MR, RR) formed with female splines 14 for inserting the spline shafts 13 of the constant velocity joints 12 for wheels through the through-holes passing through the center of the wheels 2a in the axial direction. In the case of the wheel bearing rolling bearing unit 1a for the rear wheels of the vehicle and all the wheels of the 4WD vehicle), by installing the recessed portion 11a on the outer end surface of the hub wheel 2a, it is possible to assemble the constant velocity joint 12 for the wheel ( The tightening workability of the nut screwed into the tip end portion of the spline shaft 13 can be improved.

上述の様な車輪支持用転がり軸受ユニット１、１ａを自動車に組み付けるには、外輪４の外周面に形成した外向フランジ状の取付部１５をナックル等の懸架装置の構成部品にねじ止め固定する事により、上記外輪４を懸架装置に支持する。又、ハブ輪２、２ａの外周面に形成したフランジ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。   In order to assemble the wheel bearing rolling bearing units 1 and 1a as described above to the automobile, the outward flange-shaped mounting portion 15 formed on the outer peripheral surface of the outer ring 4 is screwed and fixed to a component part of a suspension device such as a knuckle. Thus, the outer ring 4 is supported by the suspension device. Further, the wheels are fixed to flanges 6 formed on the outer peripheral surfaces of the hub wheels 2 and 2a. As a result, this wheel can be rotatably supported with respect to the suspension device.

上述の様な車輪支持用転がり軸受ユニット１、１ａを構成するハブ輪２、２ａは、熱間鍛造性や切削性を確保する事を考慮して、Ｓ５３Ｃ等の中炭素鋼で造っている。製造時には、先ず、所定長さに切断した棒状の素材を、高周波誘導加熱により１１００〜１２００℃程度のオーステナイト域まで加熱してから、熱間鍛造により所定の形状とした後、放冷する。この加工作業の際、オーステナイト粒界から初析フェライトが析出した後、室温程度に冷却されるまでの間に起こるパーライト変態によって、初析フェライトとパーライトとが複合した組織が得られる。この様な組織の大部分は、焼き入れ、焼き戻し等の熱処理を施す事なく、そのまま使用される。これに対して、図４に示す構造の場合、同図に斜格子で示す様に、フランジ６の軸方向内側面側の付け根部分及び前記第一の内輪軌道７ａから段部８までの領域に、転がり疲労寿命確保、及び、嵌合部のフレッチング防止の為に、高周波焼き入れによる硬化層を形成する事が行なわれている。   The hub wheels 2 and 2a constituting the wheel bearing rolling bearing units 1 and 1a as described above are made of medium carbon steel such as S53C in consideration of ensuring hot forgeability and cutting performance. At the time of manufacture, first, a rod-shaped material cut into a predetermined length is heated to an austenite region of about 1100 to 1200 ° C. by high-frequency induction heating, and after cooling to a predetermined shape by hot forging, it is allowed to cool. In this processing operation, a structure in which the pro-eutectoid ferrite and pearlite are combined is obtained by pearlite transformation that occurs during the period from the precipitation of pro-eutectoid ferrite from the austenite grain boundary to the cooling to room temperature. Most of such structures are used as they are without being subjected to heat treatment such as quenching and tempering. On the other hand, in the case of the structure shown in FIG. 4, as shown by the oblique grid in FIG. 4, in the root portion on the inner side in the axial direction of the flange 6 and the region from the first inner ring raceway 7 a to the step portion 8. In order to secure a rolling fatigue life and prevent fretting of the fitting portion, a hardened layer is formed by induction hardening.

又、近年、自動車の燃費向上並びに走行性能の向上の為、車輪支持用転がり軸受ユニット１の軽量化に関する要求が高くなっており、車輪を支持する為のフランジ６の薄肉化に就いても考慮されている。但し、上記フランジ６を薄肉化すると、このフランジ６の付け根部分の強度が弱くなる為、薄肉化するに就いては、強度確保の為に十分な配慮を行なう必要がある。   In recent years, in order to improve the fuel efficiency and driving performance of automobiles, there has been an increasing demand for weight reduction of the rolling bearing unit 1 for supporting the wheel, and consideration is given to the thinning of the flange 6 for supporting the wheel. Has been. However, when the flange 6 is thinned, the strength of the base portion of the flange 6 is weakened. Therefore, when thinning, it is necessary to give sufficient consideration to ensure the strength.

特に、上記フランジ６の外側面側の付け根部分には、旋回走行時等に、懸架装置と車輪との間で上記車輪支持用転がり軸受ユニット１に加わるモーメント荷重によって、曲げ応力が集中する。この為、何らの対策も施さない場合には、金属疲労に基づいて、亀裂等の損傷が生じる可能性がある。一方、上記フランジ６の内側面側の付け根部分は、前述した通り、高周波焼き入れによる硬化層が形成されて高強度になっている為、上記外側面側の付け根部分よりも、疲労強度が高くなっており、亀裂等の損傷が生じる可能性は低い。この様な事情に鑑みて、特許文献１には、フランジの外側面側の付け根部分にも、内側面側の付け根部分と同様に、高周波焼き入れによる表面硬化層を形成する事によって、このフランジの外側面側の付け根部分の強度向上を図った構造が記載されている。又、素材のハイカーボン化等により材料の強度を向上させて、上記フランジの外側面側の付け根部分の強度向上を図る構造も記載されている。   In particular, bending stress is concentrated on the base portion on the outer surface side of the flange 6 due to a moment load applied to the wheel support rolling bearing unit 1 between the suspension device and the wheel during turning. For this reason, if no measures are taken, damage such as cracks may occur based on metal fatigue. On the other hand, the root portion on the inner surface side of the flange 6 has a high strength because a hardened layer is formed by induction hardening as described above, and therefore has higher fatigue strength than the root portion on the outer surface side. Therefore, the possibility of damage such as cracks is low. In view of such circumstances, Patent Document 1 discloses that this flange is formed by forming a hardened surface layer by induction hardening at the root portion on the outer surface side of the flange, similarly to the root portion on the inner surface side. The structure which aimed at the intensity | strength improvement of the base part of the outer surface side of is described. Also described is a structure in which the strength of the material is improved by increasing the carbon content of the material to improve the strength of the base portion on the outer surface side of the flange.

又、より軽量化を進める為に、後述する本発明の実施例を示す図１の様に、フランジ６の薄肉化と共に、ハブ輪２の外端面に設けた凹入部１１ｂ部分を更に除肉する事が考えられる。この為、上記図１の構造では、この凹入部１１ｂの底部をより軸方内方に凹ませている。これにより、上記車輪支持用転がり軸受ユニット１の更なる軽量化を図れる。しかし、上述した様に、フランジ６の付け根部分の強度向上を図った構造で、上記凹入部１１ｂを除肉した場合、この凹入部１１ｂで破損が生じる可能性がある。即ち、上記フランジ６の付け根部分の強度が高いと、旋回走行時等に、懸架装置と車輪との間で上記車輪支持用転がり軸受ユニット１に加わるモーメント荷重によって上記凹入部１１ｂに作用する応力が大きくなる。この為、この凹入部１１ｂで疲労による亀裂等の破損が生じ易くなる。特に、この凹入部１１ｂを除肉する事により、この凹入部１１ｂの表面と上記ハブ輪２の外周面との距離が小さくなり、例えば、図１のイ部分の肉厚が薄くなる為、このイ部分の様な薄肉部分で破損が生じ易くなる。   In order to further reduce the weight, as shown in FIG. 1 showing an embodiment of the present invention, which will be described later, the flange 6 is thinned, and the recessed portion 11b provided on the outer end surface of the hub wheel 2 is further thinned. Things can be considered. For this reason, in the structure of FIG. 1 described above, the bottom of the recessed portion 11b is recessed more inward in the axial direction. Thereby, the further weight reduction of the said rolling bearing unit 1 for wheel support can be achieved. However, as described above, when the recessed portion 11b is thinned with a structure in which the strength of the base portion of the flange 6 is improved, the recessed portion 11b may be damaged. In other words, if the strength of the base portion of the flange 6 is high, a stress acting on the recessed portion 11b due to a moment load applied to the wheel supporting rolling bearing unit 1 between the suspension device and the wheel during turning traveling or the like. growing. For this reason, breakage such as cracks due to fatigue tends to occur in the recessed portion 11b. In particular, by removing the thickness of the recessed portion 11b, the distance between the surface of the recessed portion 11b and the outer peripheral surface of the hub wheel 2 is reduced. For example, the thickness of the portion A in FIG. Damage is likely to occur in thin parts such as a.

又、図４、５に示したハブ輪２、２ａは、熱間鍛造により所定の形状に形成される。従って、旋削等の加工を施されていない状態のハブ輪２、２ａの表面には脱炭層が存在する。前記凹入部１１、１１ａの表面は、これらハブ輪２、２ａの外周面の様に、内輪軌道７ａや段部８を形成する為の旋削加工等を施さない為、これらハブ輪２、２ａに所定の加工を施した後でも上記脱炭層が残存する。この脱炭層は疲労亀裂が発生し易い為、上記凹入部１１、１１ａの表面にこの脱炭層が存在する場合には、これら凹入部１１、１１ａの表面が疲労により破損し易くなる。更に、上記ハブ輪２、２ａの表面で上記内輪軌道７ａ乃至段部８部分や上記フランジ６の付け根部分には、前述の様に、疲労強度を向上させる為、高周波焼き入れを施す場合があるが、上記凹入部は、通常、焼き入れ、焼き戻し等の熱処理を施す事なく、そのまま使用される。熱処理を施していない非調質鋼の疲労現象は、先ず鋼の表面に疲労による亀裂が発生し、この亀裂が成長して破壊へと進行する。従って、脱炭層が存在すると共に調質を施さない、上記凹入部１１、１１ａでは、疲労による破損が生じ易い。   The hub wheels 2 and 2a shown in FIGS. 4 and 5 are formed into a predetermined shape by hot forging. Accordingly, a decarburized layer is present on the surfaces of the hub wheels 2 and 2a that are not subjected to machining such as turning. Since the surfaces of the recessed portions 11 and 11a are not subjected to turning or the like for forming the inner ring raceway 7a and the stepped portion 8 like the outer peripheral surfaces of the hub wheels 2 and 2a, The decarburized layer remains even after the predetermined processing. Since this decarburized layer is prone to fatigue cracks, when this decarburized layer is present on the surfaces of the recessed portions 11 and 11a, the surfaces of the recessed portions 11 and 11a are easily damaged by fatigue. Further, the inner ring raceway 7a to the stepped portion 8 and the base portion of the flange 6 on the surface of the hub wheel 2, 2a may be subjected to induction hardening in order to improve fatigue strength as described above. However, the recessed portion is usually used as it is without being subjected to heat treatment such as quenching or tempering. In the fatigue phenomenon of non-heat treated steel that has not been heat-treated, a crack due to fatigue is first generated on the surface of the steel, and this crack grows and progresses to fracture. Therefore, in the recessed portions 11 and 11a where the decarburized layer exists and is not tempered, damage due to fatigue is likely to occur.

特開２００２−８７００８号公報JP 2002-87008 A

本発明は、上述の様な事情に鑑みて、車輪支持用転がり軸受ユニットの軽量化の為、フランジを薄肉化すると共に凹入部を除肉した構造で、このフランジの付け根部分の強度を高くした場合でも、この凹入部に破損が生じ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 the flange is thinned and the recessed portion is thinned to reduce the weight of the wheel bearing rolling bearing unit, and the strength of the base portion of the flange is increased. Even in this case, the present invention has been invented to realize a structure in which the recess is not easily damaged.

本発明の車輪支持用転がり軸受ユニットは、何れの構造も、前述した従来から知られている車輪支持用転がり軸受ユニットと同様に、外輪と、ハブ輪と、外輪軌道と、内輪軌道と、複数個の転動体と、フランジとを備える。
このうちの外輪は、使用時に懸架装置に支持されて回転しない。
又、上記ハブ輪は、この外輪の内径側にこの外輪と同心に配置されて、使用時に車輪を結合固定してこの車輪と共に回転する。
又、上記外輪軌道は、上記外輪の内周面に設けられている。
又、上記内輪軌道は、上記ハブ輪の外周面に設けられている。
又、上記各転動体は、この内輪軌道と上記外輪軌道との間に設けられている。
又、上記フランジは、上記ハブ輪の外端部外周面に設けられており、上記車輪を結合固定する為のものである。
そして、上記ハブ輪の外端部に、外端面を軸方向内方に凹ませた凹入部を形成している。
特に、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、上記凹入部の表面に旋削加工を施す事により、この表面から脱炭層を除去すると共に、この表面の粗さを２５μｍＲa 以下としている。
又、請求項６に記載した車輪支持用転がり軸受ユニットに於いては、上記凹入部の表面に旋削加工を施す事によりこの表面から脱炭層を除去した後、この表面に、残留圧縮応力を生じさせる加工を施している。 The wheel support rolling bearing unit of the present invention has the same structure as the above-described conventionally known wheel support rolling bearing unit, and includes an outer ring, a hub ring, an outer ring raceway, an inner ring raceway, and a plurality of structures. Each rolling element and a flange.
Of these, the outer ring is supported by the suspension device during use and does not rotate.
Further, the hub wheel is disposed concentrically with the outer ring on the inner diameter side of the outer ring, and the wheel is coupled and fixed during use and rotates together with the wheel.
The outer ring raceway is provided on the inner peripheral surface of the outer ring.
The inner ring raceway is provided on the outer peripheral surface of the hub ring.
Each of the rolling elements is provided between the inner ring raceway and the outer ring raceway.
The flange is provided on the outer peripheral surface of the outer end portion of the hub wheel, and is used for coupling and fixing the wheel.
And the recessed part which dented the outer end surface to the axial direction inward was formed in the outer end part of the said hub ring | wheel.
In particular, in the rolling bearing unit for supporting a wheel according to claim 1, the decarburized layer is removed from the surface of the recess by turning the surface, and the roughness of the surface is reduced to 25 μm R a It is as follows.
Further, in the rolling bearing unit for wheel support described in claim 6, after removing the decarburized layer from the surface by turning the surface of the recessed portion, residual compressive stress is generated on the surface. Processing to make it.

上述の様に構成する本発明の車輪支持用転がり軸受ユニットによれば、凹入部の疲労強度を向上させる事ができる為、この凹入部で破損が生じにくくなる。
即ち、請求項１に記載した車輪支持用転がり軸受ユニットの場合、この凹入部の表面に旋削加工を施す事によりこの凹入部表面に存在する脱炭層を除去している為、この凹入部で疲労による亀裂が発生しにくい。又、この凹入部の表面粗さを２５μｍＲa 以下としている為、この凹入部で応力集中が生じにくくなり、この凹入部の疲労強度を高くできる。この様に、請求項１に記載した構造の場合、この凹入部に旋削加工を施す事により、脱炭層を除去すると共にこの凹入部の表面粗さを規制している為、この凹入部で破損が生じにくくなる。 According to the rolling bearing unit for supporting a wheel of the present invention configured as described above, since the fatigue strength of the recessed portion can be improved, the recessed portion is less likely to be damaged.
That is, in the case of the rolling bearing unit for supporting a wheel according to claim 1, since the decarburized layer existing on the surface of the recessed portion is removed by turning the surface of the recessed portion, fatigue is caused at the recessed portion. It is difficult to crack due to. Further, the surface roughness of the concave portion because of the less 25MyumR a, hardly stress concentration occurs in this recess, can increase the fatigue strength of the recess. Thus, in the case of the structure described in claim 1, since the decarburized layer is removed and the surface roughness of the recessed portion is restricted by turning the recessed portion, the damaged portion is damaged. Is less likely to occur.

一方、請求項６に記載した車輪支持用転がり軸受ユニットの場合、凹入部の表面から脱炭層を除去した事に加えて、この表面に残留圧縮応力を生じさせる加工を施している為、この凹入部の疲労強度をより向上させる事ができる。尚、この様に、凹入部の表面に残留圧縮応力を生じさせれば、この表面の粗さが大きくても、十分にこの凹入部の疲労強度を向上させる事ができる。
上述の様に、凹入部の疲労強度を十分に高くできれば、車輪支持用転がり軸受ユニットの軽量化の為、フランジを薄肉化すると共にこの凹入部を除肉した構造で、このフランジの付け根部分の強度を高くした場合でも、この凹入部に破損が生じにくい構造を実現できる。 On the other hand, in the case of the rolling bearing unit for wheel support described in claim 6, in addition to the removal of the decarburized layer from the surface of the recessed portion, the surface is subjected to processing that generates residual compressive stress. The fatigue strength at the entrance can be further improved. In this way, if residual compressive stress is generated on the surface of the recessed portion, the fatigue strength of the recessed portion can be sufficiently improved even if the roughness of the surface is large.
As described above, if the fatigue strength of the recessed portion can be sufficiently increased, the flange is thinned and the recessed portion is thinned to reduce the weight of the wheel bearing rolling bearing unit. Even when the strength is increased, it is possible to realize a structure in which the recess is less likely to be damaged.

請求項１に記載した構造を実施する為に好ましくは、請求項２に記載した様に、上記凹入部の表面の粗さを６μｍＲa 以下とする。
この様に構成すれば、上記凹入部の表面に生じる応力集中をより軽減し、この凹入部の疲労強度をより向上させる事ができる。
又、好ましくは、請求項３に記載した様に、上記凹入部の表面に旋削加工を施した後に、この表面にHRC ４０以上の硬化層を形成する。
この様に構成すれば、上記凹入部で疲労による亀裂が発生しにくくなり、この凹入部の疲労強度をより向上させる事ができる。尚、旋削加工を施さず、この凹入部の表面に脱炭層が存在する状態で硬化層を形成した場合、この凹入部の表面に軟質のフェライトが残存している為、この凹入部の硬度を向上させる事ができない。従って、本発明では、この凹入部の表面に硬化層を形成するのに先立って、この凹入部に旋削加工を施して脱炭層を除去している。
又、上記凹入部に硬化層を形成する場合に好ましくは、請求項４に記載した様に、焼き入れにより行なう。尚、この場合、上記ハブ輪を、Ｃ（炭素）を０．５重量％以上含む炭素鋼製とする。
この様に構成すれば、上記凹入部の表面に十分に硬度の高い硬化層を形成する事ができる。
更に、請求項５に記載した様に、焼き入れにより硬化層を形成した後、上記凹入部の表面にショットピーニング或はターニング加工を施す事が好ましい。
この様に構成すれば、上記凹入部の表面に残留圧縮応力を付与して、この凹入部の疲労強度をより向上させる事ができる。 Preferably in order to implement the structure described in claim 1, as set forth in claim 2, or less 6MyumR a roughness of the surface of the recess.
If comprised in this way, the stress concentration which arises on the surface of the said recessed part can be reduced more, and the fatigue strength of this recessed part can be improved more.
Preferably, as described in claim 3, after turning the surface of the recessed portion, a hardened layer of H R C 40 or more is formed on the surface.
If comprised in this way, it will become difficult to generate | occur | produce the crack by fatigue at the said recessed part, and the fatigue strength of this recessed part can be improved more. In addition, when the hardened layer is formed in a state where the decarburized layer is present on the surface of the recessed portion without performing a turning process, since soft ferrite remains on the surface of the recessed portion, the hardness of the recessed portion is reduced. I can't improve it. Therefore, in the present invention, prior to forming the hardened layer on the surface of the recessed portion, the decarburized layer is removed by turning the recessed portion.
Moreover, when forming a hardened layer in the said recessed part, Preferably it carries out by quenching as described in Claim 4. In this case, the hub ring is made of carbon steel containing 0.5% by weight or more of C (carbon).
If comprised in this way, the hardened layer with sufficiently high hardness can be formed in the surface of the said recessed part.
Furthermore, as described in claim 5, it is preferable that after the hardened layer is formed by quenching, the surface of the recessed portion is subjected to shot peening or turning.
If comprised in this way, the residual compressive stress can be provided to the surface of the said recessed part, and the fatigue strength of this recessed part can be improved more.

一方、請求項６に記載した構造を実施する為に好ましくは、請求項７に記載した様に、脱炭層を除去した後で残留圧縮応力を生じさせる加工を施す前に、凹入部の表面に、焼き入れによりHRC ４０以上の硬化層を形成する。尚、この場合も、上記ハブ輪を、Ｃを０．５重量％以上含む炭素鋼製とする。
この様に構成すれば、上記凹入部の表面の疲労強度をより向上させる事ができる。
又、請求項８に記載した様に、上記残留圧縮応力を生じさせる加工としては、ショットピーニングが好ましい。
この様に構成すれば、上記凹入部の表面に効率良く残留圧縮応力を生じさせる事ができる。 On the other hand, in order to carry out the structure described in claim 6, preferably, as described in claim 7, the surface of the recessed portion is formed on the surface of the indented portion after the decarburized layer is removed and the residual compressive stress is generated. Then, a hardened layer of H R C 40 or more is formed by quenching. In this case as well, the hub wheel is made of carbon steel containing 0.5% by weight or more of C.
If comprised in this way, the fatigue strength of the surface of the said recessed part can be improved more.
Further, as described in claim 8, shot peening is preferable as the processing for generating the residual compressive stress.
If comprised in this way, a residual compressive stress can be efficiently produced in the surface of the said recessed part.

図１は、本発明の実施例を示している。尚、本発明の特徴は、ハブ輪２の外端面を軸方向内方に凹ませた凹入部１１ｂの疲労強度を向上させるべく、この凹入部１１ｂの表面に所定の処理を施す点にある。その他の部分の構造及び作用は、前述の図４に示した従来構造と同様であるから、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。本実施例の場合、上記ハブ輪２の軽量化の為に、フランジ６を薄肉化すると共に、上記凹入部１１ｂを除肉した構造としている。この為、この凹入部１１ｂを、上記図４に示した凹入部１１よりも軸方向内方に凹ませている。又、本実施例の場合、図１に斜格子で示す様に、上記フランジ６の付け根部分の内外両側面、及び、内輪軌道７ａ乃至段部８部分に、高周波焼き入れを施す事により硬化層を形成して、これら各部分の強度を高くしている。   FIG. 1 shows an embodiment of the present invention. A feature of the present invention is that a predetermined treatment is applied to the surface of the recessed portion 11b in order to improve the fatigue strength of the recessed portion 11b in which the outer end surface of the hub wheel 2 is recessed inward in the axial direction. Since the structure and operation of the other parts are the same as those of the conventional structure shown in FIG. 4 described above, the overlapping description will be omitted or simplified, and the following description will focus on the characteristic parts of this embodiment. In the case of the present embodiment, in order to reduce the weight of the hub wheel 2, the flange 6 is thinned and the recessed portion 11b is thinned. Therefore, the recessed portion 11b is recessed inward in the axial direction from the recessed portion 11 shown in FIG. In the case of the present embodiment, as shown by a diagonal lattice in FIG. 1, the hardened layer is obtained by subjecting both the inner and outer side surfaces of the base portion of the flange 6 and the inner ring raceway 7a to the stepped portion 8 to induction hardening. The strength of each part is increased.

特に、本実施例の場合、上記ハブ輪２が、Ｃを０．５重量％以上含む炭素鋼製であり、上記凹入部１１ｂの表面に旋削加工を施す事により、この表面から脱炭層を除去すると共に、この表面の粗さを２５μｍＲa 以下としている。尚、好ましくは、この表面の粗さを６μｍＲa 以下とする。そして、この凹入部１１ｂの表面に旋削加工を施した後に、この表面にHRC ４０以上の硬化層１６（斜格子部分）を形成している。即ち、本実施例の場合、この凹入部１１ｂの表面に存在する脱炭層を、旋削加工により除去してから、上記硬化層１６を形成している。この硬化層１６は、高周波焼き入れにより形成されている。尚、この硬化層１６を形成した後に、更にショットピーニング或はターニング加工を施す事が好ましい。 In particular, in the case of the present embodiment, the hub wheel 2 is made of carbon steel containing 0.5% by weight or more of C, and the decarburized layer is removed from the surface by turning the surface of the recessed portion 11b. while, it is less 25MyumR a roughness of the surface. In addition, Preferably, the roughness of this surface shall be 6 micrometers Ra or less. Then, after turning the surface of the recessed portion 11b, a hardened layer 16 (oblique lattice portion) of H R C 40 or more is formed on the surface. That is, in this embodiment, the hardened layer 16 is formed after the decarburized layer present on the surface of the recessed portion 11b is removed by turning. The hardened layer 16 is formed by induction hardening. In addition, after forming this hardened layer 16, it is preferable to perform a shot peening or a turning process further.

上述の様に構成する本実施例の車輪支持用転がり軸受ユニットによれば、上記凹入部１１ｂの疲労強度を向上させる事ができる為、この凹入部１１ｂで破損が生じにくくなる。即ち、この凹入部１１ｂの表面に旋削加工を施す事によりこの凹入部１１ｂ表面に存在し、疲労による亀裂の発生原因となり易い脱炭層を除去している為、この凹入部１１ｂで疲労による亀裂が発生しにくくなる。又、この凹入部１１ｂの表面粗さを２５μｍＲa 以下としている為、この凹入部１１ｂで応力集中が生じにくくなり、この凹入部１１ｂの疲労強度を高くできる。即ち、表面粗さが大きいと、応力が集中する部分が生じ、この部分から亀裂が発生し易くなる。これに対して、上記凹入部１１ｂの表面粗さを小さくしてこの凹入部１１ｂで応力集中が生じにくくすれば、この凹入部１１ｂの疲労強度を高くできる。尚、この凹入部１１ｂの表面の粗さを６μｍＲa 以下とすれば、この凹入部１１ｂの表面に生じる応力集中をより軽減できる為、この凹入部１１ｂの疲労強度をより向上させる事ができる。この様に、本実施例の場合、この凹入部１１ｂに旋削加工を施す事により、脱炭層を除去すると共にこの凹入部１１ｂの表面粗さを規制している為、この凹入部１１ｂで破損が生じにくくなる。 According to the rolling bearing unit for supporting a wheel of the present embodiment configured as described above, the fatigue strength of the recessed portion 11b can be improved, so that the recessed portion 11b is not easily damaged. That is, by turning the surface of the recessed portion 11b, the decarburized layer that exists on the surface of the recessed portion 11b and easily causes cracking due to fatigue is removed, so that the crack due to fatigue occurs in the recessed portion 11b. Less likely to occur. Further, the surface roughness of the recess 11b because of the less 25MyumR a, stress concentration hardly occurs in the recessed portion 11b, it can increase the fatigue strength of the recessed portion 11b. That is, when the surface roughness is large, a portion where stress is concentrated is generated, and cracks are likely to be generated from this portion. On the other hand, if the surface roughness of the recessed portion 11b is reduced to make it difficult for stress concentration to occur in the recessed portion 11b, the fatigue strength of the recessed portion 11b can be increased. In addition, if the roughness of the surface of this recessed part 11b shall be 6 micrometers Ra or less, since the stress concentration which arises on the surface of this recessed part 11b can be reduced more, the fatigue strength of this recessed part 11b can be improved more. Thus, in the case of the present embodiment, the decarburized layer is removed and the surface roughness of the recessed portion 11b is regulated by turning the recessed portion 11b, so that the recessed portion 11b is damaged. It becomes difficult to occur.

又、上記凹入部１１ｂの表面に旋削加工を施した後に、この表面にHRC ４０以上の硬化層１６を形成すれば、この凹入部１１ｂで疲労による亀裂が発生しにくくなり、この凹入部１１ｂの疲労強度をより向上させる事ができる。この場合、この凹入部１１ｂの表面に存在していた脱炭層を除去した後に、高周波焼き入れにより上記硬化層１６を形成すれば、この凹入部１１ｂの表面の硬度を十分に向上させる事ができる。又、この硬化層１６を形成した後に、上記凹入部１１ｂの表面にショットピーニング或はターニング加工を施せば、この凹入部１１ｂの表面に残留圧縮応力を付与して、この凹入部１１ｂの疲労強度をより向上させる事ができる。 Further, if a hardened layer 16 of H R C 40 or more is formed on the surface after turning the surface of the recessed portion 11b, cracks due to fatigue are less likely to occur in the recessed portion 11b. The fatigue strength of 11b can be further improved. In this case, if the hardened layer 16 is formed by induction hardening after removing the decarburized layer existing on the surface of the recessed portion 11b, the hardness of the surface of the recessed portion 11b can be sufficiently improved. . If the surface of the recessed portion 11b is subjected to shot peening or turning after the hardened layer 16 is formed, residual compressive stress is applied to the surface of the recessed portion 11b, and the fatigue strength of the recessed portion 11b. Can be further improved.

更に、本実施例では、上記ハブ輪２に含まれるＣの含有量を０．５重量％以上としている為、焼き入れ等の熱処理を施した部分の硬度を向上させる事ができる。即ち、Ｃの含有量が０．５重量％未満の場合には、上記ハブ輪２の外周面に形成した内輪軌道７ａ及びフランジ６の付け根部分に高周波焼き入れ等の熱処理を施しても、当該部分の硬度が十分に高くならない。この結果、転動体５、５と繰り返し転がり接触する、上記内輪軌道７ａ部分の転がり疲れ寿命が短くなったり、回転曲げ応力に対する、上記付け根部分の疲労強度も確保しにくくなる。更には、上記凹入部１１ｂに高周波焼き入れ等の熱処理を施しても、この凹入部１１ｂの表面を十分に硬化する事ができず、この凹入部１１ｂの疲労強度を十分に確保できない。これに対して、上記Ｃの含有量を０．５重量％以上とすれば、これら各部分の硬度を高くして、これら各部分の疲労強度を向上させる事ができる。尚、上記Ｃの含有量は、０．６５重量％を超えて添加しても、転がり疲れ寿命及び疲労強度をそれ以上に改善できないだけでなく、加工性が悪化する等の問題を生じる為、０．６５重量％以下とする事が好ましい。   Furthermore, in this embodiment, since the C content in the hub wheel 2 is 0.5% by weight or more, the hardness of the portion subjected to heat treatment such as quenching can be improved. That is, when the content of C is less than 0.5% by weight, the inner ring raceway 7a formed on the outer peripheral surface of the hub wheel 2 and the base portion of the flange 6 may be subjected to heat treatment such as induction hardening, The hardness of the part is not high enough. As a result, the rolling fatigue life of the inner ring raceway 7a portion that repeatedly makes rolling contact with the rolling elements 5 and 5 is shortened, and it is difficult to ensure the fatigue strength of the root portion against rotational bending stress. Furthermore, even if heat treatment such as induction hardening is performed on the recessed portion 11b, the surface of the recessed portion 11b cannot be sufficiently cured, and the fatigue strength of the recessed portion 11b cannot be sufficiently secured. On the other hand, if the C content is 0.5% by weight or more, the hardness of each part can be increased and the fatigue strength of each part can be improved. In addition, even if the content of C is more than 0.65% by weight, not only the rolling fatigue life and fatigue strength cannot be further improved, but also problems such as deterioration of workability occur. It is preferable to be 0.65% by weight or less.

上述の様に、本発明によれば、上記凹入部１１ｂの疲労強度を十分に高くできる。この為、車輪支持用転がり軸受ユニットの軽量化の為、上記フランジ６を薄肉化すると共にこの凹入部１１ｂを除肉した構造で、このフランジ６の内外両側面に硬化層を形成した場合でも、この凹入部１１ｂに破損が生じにくい構造を実現できる。この結果、車輪支持用転がり軸受ユニットの信頼性を確保しつつ軽量化を図れる。尚、本実施例では、従動輪用の車輪支持用転がり軸受ユニットに就いて説明したが、本発明は、前述の図５に示した様な、駆動輪用の車輪支持用転がり軸受ユニットにも適用できる。   As described above, according to the present invention, the fatigue strength of the recessed portion 11b can be sufficiently increased. For this reason, in order to reduce the weight of the wheel bearing rolling bearing unit, the flange 6 is thinned and the recessed portion 11b is thinned, and even when a hardened layer is formed on both the inner and outer sides of the flange 6, It is possible to realize a structure in which the recess 11b is not easily damaged. As a result, weight reduction can be achieved while ensuring the reliability of the wheel bearing rolling bearing unit. In the present embodiment, the wheel support rolling bearing unit for the driven wheel has been described. However, the present invention also applies to the wheel support rolling bearing unit for the drive wheel as shown in FIG. Applicable.

次に、本発明の効果を確認する為に行なった実験に就いて説明する。
実験では、車輪支持用転がり軸受ユニットを構成するハブ輪２の素材として、Ｓ５５Ｃ（材料１）及びＳ６５Ｃ（材料２）を使用した。そして、それぞれの材料に就いて、上述の図１に示した様なハブ輪２を形成した。従って、本実験で使用したハブ輪２は、フランジ６を薄肉化すると共に凹入部１１ｂを除肉し、更にこのフランジ６の付け根部分の内外両側面に硬化層を形成している。又、本実験に使用したハブ輪２は、それぞれが同じ形状及び大きさを有しており、上記フランジ６の軸方向の厚さ及び上記凹入部１１ｂの除肉量も互いに同じである。そして、次述する表１に示す様に、この凹入部１１ｂに各種処理を施して、この凹入部１１ｂの表面の硬さ及び表面粗さを所定の値とした、本発明の範囲に属する１３種類の試料（実施例１〜１３）と、本発明の範囲からは外れる６種類の試料（比較例１〜６）とを造った。 Next, an experiment conducted for confirming the effect of the present invention will be described.
In the experiment, S55C (Material 1) and S65C (Material 2) were used as materials of the hub wheel 2 constituting the wheel bearing rolling bearing unit. And about each material, the hub ring 2 as shown in the above-mentioned FIG. 1 was formed. Therefore, the hub wheel 2 used in this experiment thins the flange 6 and removes the recessed portion 11b, and further forms a hardened layer on both inner and outer side surfaces of the base portion of the flange 6. The hub wheels 2 used in this experiment have the same shape and size, and the axial thickness of the flange 6 and the thickness of the recessed portion 11b are the same. Then, as shown in Table 1 described below, the recess 11b is subjected to various treatments, and the hardness and surface roughness of the recess 11b are set to predetermined values. Types of samples (Examples 1 to 13) and six types of samples (Comparative Examples 1 to 6) deviating from the scope of the present invention were prepared.

Figure 2005145313
Figure 2005145313

尚、上記凹入部１１ｂの表面粗さは、次の条件で送り量及び切り込み量を変化させて、この凹入部１１ｂに旋削加工を施す事により上記表１に示した値となる様にした。
周速 ： ２５０m/min
送り ： ０．３０〜０．７０mm/rev
又、上記凹入部１１ｂの表面の硬さはロックウェルＣスケールにより測定し、この凹入部１１ｂの表面粗さは中心線平均粗さを測定した。尚、実施例７、１２に就いては、旋削により脱炭層を除去する加工を施したのみで、表面粗さを小さく（良好に）する程の加工はしなかった。又、比較例１、５に就いては、旋削加工を施さず表面に脱炭層が残存したままとした。この為、これら各例の表面粗さに就いては測定せず、上記表１の表面粗さの欄に「〜」で示した。又、実施例１〜４は請求項１に、実施例５〜６は請求項１〜２に、上記実施例７は請求項６、８に、実施例８〜１１は請求項３〜４に、上記実施例１２は請求項７〜８に、実施例１３は請求項５に、それぞれ対応している。 The surface roughness of the recessed portion 11b was changed to the value shown in Table 1 by turning the recessed portion 11b by changing the feed amount and the cutting amount under the following conditions.
Peripheral speed: 250m / min
Feeding: 0.30 to 0.70mm / rev
Moreover, the hardness of the surface of the said recessed part 11b was measured by the Rockwell C scale, and the surface roughness of this recessed part 11b measured the centerline average roughness. In Examples 7 and 12, only the process of removing the decarburized layer was performed by turning, but the process was not performed so as to make the surface roughness small (good). For Comparative Examples 1 and 5, the turning process was not performed and the decarburized layer remained on the surface. For this reason, the surface roughness of each of these examples was not measured, and is indicated by “˜” in the surface roughness column of Table 1 above. Examples 1 to 4 are in Claim 1, Examples 5 to 6 are in Claims 1 and 2, Example 7 is in Claims 6 and 8, and Examples 8 to 11 are in Claims 3 to 4. The embodiment 12 corresponds to claims 7 to 8, and the embodiment 13 corresponds to claim 5.

本実験では、上述の様な各試料を、図２に示す様な試験装置に組み込んで、各試料毎の耐久時間を調べた。この図２に示した試験装置では、外輪４を治具１７により固定すると共に、ハブ輪２にラジアル荷重及びアキシアル荷重Ｆを付与する構造とした。このうちのラジアル荷重は、主に車体の重量によりハブ輪２に作用する荷重を想定しており、アキシアル荷重Ｆは、旋回時にこのハブ輪２に作用する曲げ応力を想定している。この試験の条件は次の通りである。
回転速度 ： ３００min-1
ラジアル荷重 ： ４０００Ｎ
アキシアル荷重 ： ３５００Ｎ In this experiment, each sample as described above was incorporated in a test apparatus as shown in FIG. 2, and the durability time for each sample was examined. In the test apparatus shown in FIG. 2, the outer ring 4 is fixed by the jig 17 and a radial load and an axial load F are applied to the hub ring 2. Of these, the radial load assumes a load acting on the hub wheel 2 mainly due to the weight of the vehicle body, and the axial load F assumes a bending stress acting on the hub wheel 2 during turning. The conditions of this test are as follows.
Rotational speed: 300min -1
Radial load: 4000N
Axial load: 3500N

実験では、この様な条件で、ハブ輪２にラジアル荷重及びアキシアル荷重を負荷しつつ、このハブ輪２を上述の回転速度で回転させた。そして、上記凹入部１１ｂの表面に亀裂等の破損が生じるまでの時間（耐久時間）を調べた。この結果を上記表１及び図３に示す。尚、図３は材料１の結果のみを示している。この図３では、「△」が上記凹入部１１ｂの表面に硬化層がある場合、「◇」は硬化層がない場合の結果を、それぞれ示している。又、黒く塗りつぶした方の印は、硬化層の有無が「△」「◇」に対応するが、本発明の範囲に属さない比較例の結果を示している。尚、上記耐久時間は、比較例１の耐久時間を１．０とした場合の比で示した。又、実施例７、１２及び比較例１、５に就いては、表面粗さを測定していない為、上記図３では、便宜的に表面粗さが０の位置にそれぞれ示した。   In the experiment, under such conditions, the hub wheel 2 was rotated at the above-described rotational speed while applying a radial load and an axial load to the hub wheel 2. And the time (durability time) until the breakage such as cracks occurred on the surface of the recessed portion 11b was examined. The results are shown in Table 1 and FIG. FIG. 3 shows only the result of material 1. In FIG. 3, “Δ” indicates the result when the hardened layer is present on the surface of the recessed portion 11 b, and “◇” indicates the result when the hardened layer is not present. Also, the black mark indicates the result of the comparative example in which the presence or absence of the hardened layer corresponds to “Δ” or “◇” but does not belong to the scope of the present invention. In addition, the said durable time was shown by the ratio when the durable time of the comparative example 1 was set to 1.0. Further, since the surface roughness was not measured for Examples 7 and 12 and Comparative Examples 1 and 5, in FIG. 3, the surface roughness is shown at a position where the surface roughness is 0 for convenience.

上記表１及び図３から明らかな様に、本発明の範囲に属する実施例１〜１３では、材料１及び材料２の何れの場合も良好な耐久性が得られた。一方、比較例１、５は、凹入部１１ｂの表面に脱炭層が存在する為、比較例２〜４、６は、凹入部１１ｂの表面粗さが粗過ぎる為、それぞれ十分な耐久寿命を得られなかった。従って、少なくとも、凹入部１１ｂに旋削加工を施して脱炭層を除去すると共に、この凹入部１１ｂの表面粗さを２５μｍＲa 以下とするか、或は、この凹入部１１ｂの表面から脱炭層を除去した後に、ショットピーニング等の残留圧縮応力を生じさせる為の加工を施せば、優れた耐久性を得られる事が分かる。 As apparent from Table 1 and FIG. 3, in Examples 1 to 13 belonging to the scope of the present invention, good durability was obtained in both cases of Material 1 and Material 2. On the other hand, since Comparative Examples 1 and 5 have a decarburized layer on the surface of the recessed portion 11b, Comparative Examples 2 to 4 and 6 each have a sufficient durability life because the surface roughness of the recessed portion 11b is too rough. I couldn't. Thus, removal of at least, is subjected to turning to remove the decarburized layer on the recessed portion 11b, or the surface roughness of the recessed portion 11b less 25MyumR a, or, a decarburized layer from the surface of the recess 11b After that, it can be seen that excellent durability can be obtained by performing processing for generating residual compressive stress such as shot peening.

本発明の実施例を示す、半部断面図。The half part sectional view showing the example of the present invention. 耐久試験を行なう為に、車輪支持用転がり軸受ユニットを治具に装着した状態で示す半部断面図。FIG. 3 is a half cross-sectional view showing a state in which a wheel support rolling bearing unit is mounted on a jig in order to perform a durability test. 実験結果を示すグラフ。The graph which shows an experimental result. 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. 同じく第２例を示す断面図。Sectional drawing which similarly shows the 2nd example.

符号の説明Explanation of symbols

１ 車輪支持用転がり軸受ユニット
２ ハブ輪
３ 内輪
４ 外輪
５ 転動体
６ フランジ
７ａ、７ｂ 内輪軌道
８ 段部
９ かしめ部
１０ 外輪軌道
１１ 取付部
１１、１１ａ、１１ｂ 凹入部
１２ 車輪用等速ジョイント
１３ スプライン軸
１４ 雌スプライン
１５ 取付部
１６ 硬化層
１７ 治具
１８ 円筒部 DESCRIPTION OF SYMBOLS 1 Rolling bearing unit for wheel support 2 Hub wheel 3 Inner ring 4 Outer ring 5 Rolling body 6 Flange 7a, 7b Inner ring track 8 Step part 9 Caulking part 10 Outer ring track 11 Mounting part 11, 11a, 11b Recessed part 12 Constant velocity joint 13 for wheel Spline shaft 14 Female spline 15 Mounting portion 16 Hardened layer 17 Jig 18 Cylindrical portion

Claims (8)

使用時に懸架装置に支持されて回転しない外輪と、この外輪の内径側にこの外輪と同心に配置されて、使用時に車輪を結合固定してこの車輪と共に回転するハブ輪と、この外輪の内周面に設けられた外輪軌道と、このハブ輪の外周面に設けられた内輪軌道と、この内輪軌道と上記外輪軌道との間に設けられた複数個の転動体と、このハブ輪の外端部外周面に設けられた、上記車輪を結合固定する為のフランジとを備えており、このハブ輪の外端面を軸方向内方に凹ませた凹入部としている車輪支持用転がり軸受ユニットに於いて、この凹入部の表面に旋削加工を施す事により、この表面から脱炭層を除去すると共に、この表面の粗さを２５μｍＲa 以下とした事を特徴とする車輪支持用転がり軸受ユニット。 An outer ring that is supported by a suspension device and does not rotate during use, a hub ring that is arranged concentrically with the outer ring on the inner diameter side of the outer ring, and that is coupled and fixed with the wheel during use, and an inner circumference of the outer ring An outer ring raceway provided on the surface, an inner ring raceway provided on the outer peripheral surface of the hub ring, a plurality of rolling elements provided between the inner ring raceway and the outer ring raceway, and an outer end of the hub ring. The wheel support rolling bearing unit is provided with a flange for coupling and fixing the wheel, which is provided on the outer peripheral surface of the wheel, and the outer end surface of the hub wheel is a recessed portion recessed inward in the axial direction. There are, by subjecting a turning to the surface of the recess, to remove the decarburized layer from the surface, the wheel support rolling bearing unit, characterized in that the roughness of the surface was less 25μmR a. 凹入部の表面の粗さを６μｍＲa 以下とした、請求項１に記載した車輪支持用転がり軸受ユニット。 The roughness of the surface of the recess and less 6μmR a, the wheel support rolling bearing unit according to claim 1. 凹入部の表面に旋削加工を施した後に、この表面にHRC ４０以上の硬化層を形成した、請求項１〜２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 wheel support according to claim 1, wherein a turning layer is formed on the surface of the recessed portion, and then a hardened layer of H R C 40 or more is formed on the surface. ハブ輪が、Ｃを０．５重量％以上含む炭素鋼製であり、凹入部の表面に、焼き入れにより硬化層を形成した、請求項３に記載した車輪支持用転がり軸受ユニット。   The wheel support rolling bearing unit according to claim 3, wherein the hub wheel is made of carbon steel containing 0.5 wt% or more of C, and a hardened layer is formed on the surface of the recessed portion by quenching. 焼き入れにより硬化層を形成した後、凹入部の表面にショットピーニング或はターニング加工を施した、請求項４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 claim 4, wherein the hardened layer is formed by quenching, and then the surface of the recessed portion is subjected to shot peening or turning. 使用時に懸架装置に支持されて回転しない外輪と、この外輪の内径側にこの外輪と同心に配置されて、使用時に車輪を結合固定してこの車輪と共に回転するハブ輪と、この外輪の内周面に設けられた外輪軌道と、このハブ輪の外周面に設けられた内輪軌道と、この内輪軌道と上記外輪軌道との間に設けられた複数個の転動体と、このハブ輪の外端部外周面に設けられた、上記車輪を結合固定する為のフランジとを備えており、このハブ輪の外端面を軸方向内方に凹ませた凹入部としている車輪支持用転がり軸受ユニットに於いて、この凹入部の表面に旋削加工を施す事によりこの表面から脱炭層を除去した後、この表面に、残留圧縮応力を生じさせる加工を施した事を特徴とする車輪支持用転がり軸受ユニット。   An outer ring that is supported by a suspension device and does not rotate during use, a hub ring that is arranged concentrically with the outer ring on the inner diameter side of the outer ring, and that is coupled and fixed with the wheel during use, and an inner circumference of the outer ring An outer ring raceway provided on the surface, an inner ring raceway provided on the outer peripheral surface of the hub ring, a plurality of rolling elements provided between the inner ring raceway and the outer ring raceway, and an outer end of the hub ring. The wheel support rolling bearing unit is provided with a flange for coupling and fixing the wheel, which is provided on the outer peripheral surface of the wheel, and the outer end surface of the hub wheel is a recessed portion recessed inward in the axial direction. A rolling bearing unit for supporting a wheel, characterized in that after the decarburized layer is removed from the surface of the recess by turning, the surface is subjected to a process for generating residual compressive stress. ハブ輪が、Ｃを０．５重量％以上含む炭素鋼製であり、脱炭層を除去した後で残留圧縮応力を生じさせる加工を施す前に、焼き入れによりHRC ４０以上の硬化層を形成した、請求項６に記載した車輪支持用転がり軸受ユニット。 The hub ring is made of carbon steel containing 0.5% by weight or more of C. After removing the decarburized layer and before processing to generate a residual compressive stress, a hardened layer of H R C 40 or more is formed by quenching. The rolling bearing unit for wheel support according to claim 6 formed. 残留圧縮応力を生じさせる加工がショットピーニングである、請求項６〜７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 6 to 7, wherein the processing for generating the residual compressive stress is shot peening.
JP2003387475A 2003-11-18 2003-11-18 Rolling bearing unit for supporting vehicle wheel Pending JP2005145313A (en)

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Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2007010772A1 (en) * 2005-07-20 2007-01-25 Ntn Corporation Bearing device for wheel
WO2007010774A1 (en) * 2005-07-20 2007-01-25 Ntn Corporation Process for producing bearing device for wheel
JP2007038804A (en) * 2005-08-02 2007-02-15 Ntn Corp Bearing device for wheel
JP2007038805A (en) * 2005-08-02 2007-02-15 Ntn Corp Bearing device for wheel
JP2007051750A (en) * 2005-08-19 2007-03-01 Ntn Corp Wheel bearing device
JP2007113719A (en) * 2005-10-21 2007-05-10 Ntn Corp Bearing device for wheel
JP2010084887A (en) * 2008-10-01 2010-04-15 Nsk Ltd Method of manufacturing wheel-support rolling bearing unit
JP2010089522A (en) * 2008-10-03 2010-04-22 Nsk Ltd Method for manufacturing rolling bearing unit for supporting wheel
JP2010167875A (en) * 2009-01-22 2010-08-05 Jtekt Corp Rolling bearing device
JP2011230614A (en) * 2010-04-27 2011-11-17 Nsk Ltd Method for manufacturing rolling bearing unit for supporting wheel
US8840313B2 (en) 2005-09-30 2014-09-23 Ntn Corporation Bearing apparatus for a wheel of vehicle

Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8240922B2 (en) 2005-07-20 2012-08-14 Ntn Corporation Bearing device for wheel
WO2007010774A1 (en) * 2005-07-20 2007-01-25 Ntn Corporation Process for producing bearing device for wheel
WO2007010772A1 (en) * 2005-07-20 2007-01-25 Ntn Corporation Bearing device for wheel
US8302309B2 (en) 2005-07-20 2012-11-06 Ntn Corporation Process for producing bearing device for wheel
JP2007038804A (en) * 2005-08-02 2007-02-15 Ntn Corp Bearing device for wheel
JP2007038805A (en) * 2005-08-02 2007-02-15 Ntn Corp Bearing device for wheel
JP2007051750A (en) * 2005-08-19 2007-03-01 Ntn Corp Wheel bearing device
US8840313B2 (en) 2005-09-30 2014-09-23 Ntn Corporation Bearing apparatus for a wheel of vehicle
JP2007113719A (en) * 2005-10-21 2007-05-10 Ntn Corp Bearing device for wheel
JP2010084887A (en) * 2008-10-01 2010-04-15 Nsk Ltd Method of manufacturing wheel-support rolling bearing unit
JP2010089522A (en) * 2008-10-03 2010-04-22 Nsk Ltd Method for manufacturing rolling bearing unit for supporting wheel
JP2010167875A (en) * 2009-01-22 2010-08-05 Jtekt Corp Rolling bearing device
JP2011230614A (en) * 2010-04-27 2011-11-17 Nsk Ltd Method for manufacturing rolling bearing unit for supporting wheel

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