JP2007232120A - Wheel bearing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wheel bearing device in a first to third generation structure with an inner ring fixed by rocking-caulking a hub ring for improving the strength and durability of the hub ring while suppressing the deformation of the inner ring during caulking work. <P>SOLUTION: In the wheel bearing device, the end of a small diameter stepped portion 2b before caulked is formed as a cylindrical portion 12, an annular groove 13 is formed in the outer peripheral face thereof at a depth of 0.5-1.0 mm in a range from a position corresponding to the large diameter end of an inside rolling face 3a beyond a large end face 3b, and circular faces 13a, 13b having curvature radii Ri, Ro are formed on both sides. The curvature radius Ri on the inner side is smaller than the curvature radius Ro on the outer side and set in a range of R1-10. A hardened layer 11 is formed in the small diameter stepped portion 2b with its surface hardness in a range of 50-64 HRC by induction hardening, and it is terminated at the starting point of the circular face 13b. A caulked portion 2b is kept at a surface hardness of 25 HRC or lower after forged. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a bearing device for a wheel that rotatably supports a wheel of an automobile or the like with respect to a suspension device, and more particularly, in a self-retained structure in which an inner ring is fixed by rocking caulking of a hub ring, and accompanying this caulking process. The present invention relates to a wheel bearing device that suppresses deformation of an inner ring and improves durability by increasing the strength of a hub ring.

  BACKGROUND ART A wheel bearing device for a vehicle such as an automobile is a device that supports a wheel rotatably with respect to a suspension device via a double-row rolling bearing, and includes a drive wheel and a driven wheel. As the wheel bearing device, a double-row angular ball bearing having a desired bearing rigidity, exhibiting durability against misalignment, and having a small rotational torque from the viewpoint of improving fuel efficiency is often used. As a typical example of the conventional structure, a wheel bearing device for a driven wheel as shown in FIG. 3 is known. In the following description, the side closer to the outer side of the vehicle in a state assembled to the vehicle is referred to as the outer side (left side in the drawing), and the side closer to the center is referred to as the inner side (right side in the drawing).

  This wheel bearing device is referred to as a third generation, and includes a hub wheel 51, an inner ring 52, an outer ring 53, and double-row balls 54 and 54. The hub wheel 51 integrally has a wheel mounting flange 55 for mounting a wheel (not shown) at one end, an outer side inner raceway surface 51a on the outer periphery, and an axial direction from the inner side raceway surface 51a. An extending small diameter step portion 51b is formed. Further, hub bolts 56 for fixing the wheels are planted at the circumferentially equidistant positions of the wheel mounting flanges 55.

  An inner ring 52 having an inner side inner rolling surface 52a formed on the outer periphery thereof is press-fitted into the small diameter step portion 51b of the hub wheel 51. The inner ring 52 is prevented from coming off from the hub wheel 51 in the axial direction by a caulking portion 51c formed by plastically deforming the end portion of the small diameter step portion 51b of the hub wheel 51 radially outward. .

  The outer ring 53 integrally has a vehicle body mounting flange 53b on the outer periphery, and double row outer rolling surfaces 53a and 53a are formed on the inner periphery. Double row balls 54 and 54 are accommodated so as to roll freely between the double row outer rolling surfaces 53a and 53a and the inner rolling surfaces 51a and 52a opposed to these.

  The hub wheel 51 is integrally formed by forging a carbon steel material having a carbon content of 0.40 to 0.80% by weight, and a portion indicated by an oblique lattice, that is, a wheel mounting flange 55. The surface is hardened by induction hardening or the like from the base portion to the inner rolling surface 51a and the small diameter step portion 51b. In addition, the caulking part 51c is left with the raw material surface hardness after forging. On the other hand, the inner ring 52 is made of high carbon steel such as high carbon chromium bearing steel such as SUJ2, and is hardened and hardened to the core.

As a result, a low-cost and sufficiently durable wheel bearing device can be realized, and the caulking portion 51c can be prevented from being damaged, such as a crack, and fixed to the hub wheel 51 by the caulking portion 51c. It is possible to prevent the diameter of the inner ring 52 from changing to an extent that causes a practical problem. And while reducing possibility that this inner ring | wheel 52 will be damaged with the fixing operation | work, a preload can be maintained to an appropriate value, and also cost reduction can be aimed at by reduction of a number of parts, parts processing, and an assembly man-hour.
JP-A-11-129703

  However, in this conventional wheel bearing device, when the end of the small-diameter step portion 51b of the hub wheel 51 is swung and swaged, the inner ring 52 is pushed radially outward and the inner ring 52 is deformed. I can't deny it. Here, the width of the inner ring 52 can be increased to increase the rigidity. However, if the width of the inner ring 52 is increased, not only light weight and downsizing are hindered but also an increase in cost is not preferable. The hoop stress generated in the inner ring 52 by the caulking process has a correlation with the inner ring pushing amount (caulking amount), and the hoop stress tends to increase as the inner ring pushing amount increases. Therefore, in order to prevent the occurrence of excessive hoop stress that leads to cracking of the inner ring, for example, a hoop stress of 250 MPa or more, it is necessary to reduce the inner ring pushing amount, but simply reducing the inner ring pushing amount reduces the inner ring pushing amount. Since the amount is insufficient and the fixing force of the inner ring 52 cannot be secured, there has been a demand for a method for suppressing the hoop stress and obtaining an appropriate inner ring pushing amount.

  The present invention has been made in view of such a conventional problem. In the wheel bearing device of the first to third generation structure in which the inner ring is fixed by the rocking caulking of the hub ring, it is accompanied by caulking. An object of the present invention is to provide a wheel bearing device that suppresses deformation of an inner ring and improves the strength and durability of a hub ring.

  In order to achieve such an object, the invention according to claim 1 of the present invention integrally has an outer member having a double row outer rolling surface formed on the inner periphery and a wheel mounting flange at one end. A hub wheel formed with a small-diameter step portion extending in the axial direction from the wheel mounting flange, and at least one inner ring press-fitted into the small-diameter step portion of the hub wheel through a predetermined shimoshiro, An inner member in which a double row inner rolling surface facing the outer rolling surface of the inner member is formed, and the inner member and the outer member are accommodated between the rolling surfaces of the inner member and the outer member via a cage. In the wheel bearing device, the inner ring is fixed in the axial direction by a caulking portion formed by plastically deforming an end portion of the small diameter step portion radially outward. The end of the small-diameter step portion before caulking is formed as a hollow cylindrical portion. An annular groove is formed at a depth of 5 to 1.0 mm from a position corresponding to the large-diameter end of the inner raceway surface of the inner ring over the large end surface of the inner ring, and a predetermined curvature is provided on both sides of the annular groove. An arc surface having radii Ri and Ro is formed, and the curvature radius Ri of the inner arc surface of these arc surfaces is smaller than the curvature radius Ro of the outer arc surface, and is set in a range of R1-10. A predetermined hardened layer is formed on the small-diameter step by induction hardening, and this hardened layer is stopped at the starting point of the arcuate surface on the outer side in the annular groove.

  In this way, the inner ring is fixed to the hub ring in the axial direction by the caulking portion formed by press-fitting the inner ring into the small-diameter step portion of the hub wheel and plastically deforming the end of the small-diameter step portion radially outward. In the self-retained wheel bearing device, the end portion of the small diameter step portion before caulking is formed as a hollow cylindrical portion, and the outer peripheral surface of this cylindrical portion has a depth of 0.5 to 1.0 mm, An annular groove is formed from the position corresponding to the large-diameter end of the inner raceway surface of the inner ring over the large end surface of the inner ring, and arcuate surfaces having predetermined curvature radii Ri and Ro are formed on both sides of the annular groove. Of the arcuate surfaces, the radius of curvature Ri of the inner arcuate surface is smaller than the radius of curvature Ro of the arcuate surface of the outer side and is set in the range of R1-10, and a predetermined hardened layer is formed on the small diameter step by induction hardening. Formed and this hardened layer is formed on the outer side of the annular groove. Since it is stopped at the starting point of the arc surface, it provides a wheel bearing device that secures the predetermined inner ring fixing force and suppresses deformation of the inner ring due to caulking, and improves the strength and durability of the hub ring. can do.

  Preferably, as in the invention of claim 2, the surface hardness of the hardened layer is set in a range of 50 to 64 HRC, and the crimped portion is left raw with a surface hardness of 25 HRC or less after forging. If so, the fretting wear of the hub wheel is suppressed, the strength and durability are improved, the workability of the caulking portion is improved, and the occurrence of cracks and the like due to plastic deformation can be prevented.

  According to a third aspect of the present invention, the chamfered portion on the caulking portion side of the inner ring has an arc surface having a predetermined radius of curvature r1, and the radius of curvature of the arc surface on the inner side in the annular groove. If it is smaller than Ri and set in the range of R1.0 to 2.5, the elastic deformation of the outer diameter of the inner ring caused by the caulking load is suppressed, and the hoop stress generated in the outer diameter is reduced. It is possible to suppress the occurrence of damage such as microcracks in the tightening portion.

  If the depth from the large end surface of the inner ring on the side of the caulking portion of the inner ring is set to be smaller than the width of the annular groove as in the invention described in claim 4, the plasticity of the cylindrical portion It becomes easy to deform, and a predetermined inner ring fixing force can be obtained.

  The wheel bearing device according to the present invention integrally has an outer member having a double row outer raceway formed on the inner periphery and a wheel mounting flange at one end, and extends in an axial direction from the wheel mounting flange. A double-row comprising a hub wheel having a small-diameter step portion, and at least one inner ring press-fitted into the small-diameter step portion of the hub ring through a predetermined shimeiro, and facing the outer rolling surface of the double row on the outer periphery An inner member on which an inner rolling surface is formed, and a double row rolling element that is rotatably accommodated between the inner member and the outer member via a cage. In the wheel bearing device in which the inner ring is fixed in the axial direction by a caulking portion formed by plastically deforming an end portion of the small diameter step portion radially outward, an end portion of the small diameter step portion before caulking Is formed as a hollow cylindrical portion, with a depth of 0.5 to 1.0 mm on the outer peripheral surface of this cylindrical portion, An annular groove is formed from the position corresponding to the large-diameter end of the inner raceway surface of the inner ring beyond the large end surface of the inner ring, and circular arc surfaces having predetermined curvature radii Ri and Ro are formed on both sides of the annular groove. Of these arc surfaces, the radius of curvature Ri of the arc surface on the inner side is smaller than the radius of curvature Ro of the arc surface of the outer side, and is set in a range of R1 to 10, and the small diameter step portion is predetermined by induction hardening. Since a hardened layer is formed and this hardened layer is stopped at the starting point of the outer arc surface of the annular groove, a predetermined inner ring fixing force is secured to suppress deformation of the inner ring due to caulking, and a hub It is possible to provide a wheel bearing device that improves the strength and durability of the wheel.

  A vehicle body mounting flange is integrally formed on the outer periphery, an outer member having a double row outer rolling surface formed on the inner periphery, a wheel mounting flange is integrally formed on one end, and the double row outer rolling is formed on the outer periphery. One inner rolling surface facing the running surface, a hub wheel formed with a small-diameter stepped portion extending in the axial direction from the inner rolling surface, and a small-diameter step portion of the hub wheel are press-fitted through a predetermined shimiro An inner member composed of an inner ring having an outer ring formed with the other inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and a cage between both rolling surfaces of the inner member and the outer member. The inner ring is fixed in the axial direction by a caulking portion formed by plastically deforming an end portion of the small diameter step portion radially outward. In the wheel bearing device, the end portion of the small diameter step portion before caulking is formed as a hollow cylindrical portion, and the cylindrical portion An annular groove is formed in the outer peripheral surface at a depth of 0.5 to 1.0 mm from the position corresponding to the large diameter end of the inner raceway surface of the inner ring, beyond the large end surface of the inner ring. Are formed with predetermined curvature radii Ri and Ro, and the curvature radius Ri of the inner arc surface of these arc surfaces is smaller than the curvature radius Ro of the outer arc surface, and is in the range of R1-10. In addition, a hardened layer having a surface hardness in the range of 50 to 64 HRC is formed on the small diameter step portion by induction hardening, and the hardened layer is stopped at the starting point of the arcuate surface on the outer side in the annular groove, The tightening portion is left as raw with a surface hardness of 25 HRC or less after forging.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a longitudinal sectional view showing an embodiment of a wheel bearing device according to the present invention, and FIG. 2A is an enlarged view of a main part showing a hub wheel and an inner ring before caulking in FIG.

  This wheel bearing device is referred to as the third generation on the driven wheel side, and is a double row rolling element (ball) accommodated between the inner member 1 and the outer member 10 and between both members 1 and 10 so as to roll freely. 6 and 6. The inner member 1 includes a hub ring 2 and an inner ring 3 that is press-fitted into the hub ring 2 through a predetermined scissors.

  The hub wheel 2 integrally has a wheel mounting flange 4 for mounting a wheel (not shown) at an end on the outer side, and a hub bolt for fixing the wheel at a circumferentially equidistant position of the wheel mounting flange 4. 5 is planted. Further, one (outer side) inner rolling surface 2a is directly formed on the outer periphery of the hub wheel 2, and a small-diameter step portion 2b extending in the axial direction from the inner rolling surface 2a is formed. And the inner ring | wheel 3 in which the inner side rolling surface 3a of the other (inner side) was formed in the outer periphery is press-fit in this small diameter step part 2b, and also the edge part of the small diameter step part 2b is plastically deformed to radial direction outward. The formed caulking portion 2 c prevents the inner ring 3 from coming off in the axial direction with respect to the hub wheel 2.

  The hub wheel 2 is formed of medium carbon steel containing 0.40 to 0.80% by weight of carbon, such as S53C, and includes an inner side rolling surface 2a on the outer side, a seal land part in which the seal 8 is in sliding contact, and a small diameter. The hardened layer 11 is formed in a range of 50 to 64 HRC by induction hardening over the step 2b. The caulking portion 2c is an unquenched portion having a material surface hardness of 25 HRC or less after forging. On the other hand, the inner ring 3 is made of high carbon chrome bearing steel such as SUJ2, and is hardened in the range of 58 to 64 HRC up to the core part by quenching.

  The outer member 10 integrally has a vehicle body mounting flange 10b for mounting to a vehicle body (not shown) on the outer periphery, and double row outer rolling surfaces 10a, 10a are formed on the inner periphery. The outer member 10 is formed of medium carbon steel containing 0.40 to 0.80% by weight of carbon such as S53C, as in the case of the hub wheel 2, and at least the double row outer raceway surfaces 10a and 10a are formed by induction hardening. The surface hardness is set in the range of 58 to 64 HRC. And the double row rolling elements 6 and 6 are accommodated between each rolling surface 10a, 2a and 10a, 3a, and these double row rolling elements 6 and 6 are rollably hold | maintained by the holder | retainers 7 and 7. ing. Further, seals 8 and 9 are attached to the end portion of the outer member 10 to prevent leakage of the lubricating grease sealed inside the bearing and intrusion of rainwater, dust and the like from the outside into the bearing.

  Here, the wheel bearing device referred to as the third generation in which the inner raceway surface 2a is directly formed on the outer periphery of the hub wheel 2 is illustrated, but the wheel bearing device according to the present invention is not limited to such a structure. For example, it may be a first generation or second generation structure in which a pair of inner rings are press-fitted into a small diameter step portion of a hub ring. In addition, although the double row angular contact ball bearing which used the rolling elements 6 and 6 as the ball was illustrated, it is not restricted to this, The double row tapered roller bearing which uses the tapered roller for the rolling element 6 may be sufficient.

  Here, as shown in FIG. 2, a chamfered portion 3c having an arc surface having a radius of curvature r1 of R1 to 2.5 is formed at the inner diameter end portion of the inner ring 3 on the large end surface 3b side (caulking portion side). Yes. If the curvature radius r1 of the chamfered portion 3c is set to be smaller than 1.0 mm, when a bending moment load is applied to the device during operation of the vehicle, stress concentration occurs at the root portion of the crimped portion 2c, and microcracks or the like May cause damage. On the contrary, if the radius of curvature r1 exceeds 2.5 mm, when the cylindrical portion 12 is plastically deformed, the inner ring 3 is pushed outward in the radial direction, and an excessive hoop stress is generated in the outer diameter of the inner ring 3. It is not preferable. The caulking portion 2 is indicated by a two-dot chain line in the figure.

  On the other hand, the end portion of the small diameter step portion 2b of the hub wheel 2 before caulking is formed as a hollow cylindrical portion 12, and the bottom surface 12a of the cylindrical portion 12 has a predetermined dimension from the large end surface 3b on the inner side of the inner ring 3. (Depth) a is formed. An annular groove 13 having a depth b is formed on the outer peripheral surface of the cylindrical portion 12. The annular groove 13 extends from the position corresponding to the large diameter end of the inner raceway surface 3a in the inner ring 3 to the chamfered portion 3b of the inner ring 3, and is formed in a range slightly beyond the large end surface 3b. Arc surfaces 13a and 13b having curvature radii Ri and Ro are formed on both sides of the annular groove 13, respectively. If the dimension a of the bottom surface 12a of the cylindrical portion 12 is larger than the width of the annular groove 13, the cylindrical portion 12 is easily deformed, but the caulking force is insufficient and a predetermined inner ring fixing force cannot be obtained.

  In the present embodiment, the depth b of the annular groove 13 is 0.5 to 1.0 mm, the radius of curvature Ri of the arcuate surface 13a on the inner side is larger than the radius of curvature r1 of the chamfered portion 3c of the inner ring 3, and It is set smaller than the radius of curvature Ro of the circular arc surface 13b (r1 ≦ Ri ≦ Ro), and is formed in the range of Ri = R1-10. By forming the annular groove 13 on the outer peripheral surface of the cylindrical portion 12, the cylindrical portion 12 is easily deformed during caulking, and deformation of the inner ring 3 can be suppressed. However, if the depth b of the annular groove 13 is smaller than 0.5 mm, the effect is reduced. If the depth b exceeds 1.0 mm, the inner ring pushing amount (clamping force) is insufficient and the desired inner ring is reduced. A fixing force of 3 cannot be obtained.

  The hardened layer 11 formed on the outer periphery of the hub wheel 2 is stopped at the starting point of the outer arcuate surface 13 b in the annular groove 13. Thereby, the workability of the cylindrical part 12 in the small diameter step part 2b can be improved, and the occurrence of cracks and the like due to plastic deformation can be prevented.

  Thus, in this embodiment, the end of the small-diameter step portion 2b in the hub wheel 2 before caulking is formed as a hollow cylindrical portion 12, and an annular surface having a predetermined depth b is formed on the outer peripheral surface of the cylindrical portion 12. The groove 13 is formed, and arc surfaces 13a and 13b having predetermined radii of curvature Ri and Ro are formed on both sides of the annular groove 13, and the width of the annular groove 13 is set within a predetermined range. The cylindrical portion 12 is easily deformed at the time of tightening, and the wheel bearing is provided with a predetermined inner ring fixing force to suppress deformation of the inner ring 3 due to caulking and to improve the strength and durability of the hub ring 2. An apparatus can be provided.

  The embodiment of the present invention has been described above, but the present invention is not limited to such an embodiment, and is merely an example, and various modifications can be made without departing from the scope of the present invention. Of course, the scope of the present invention is indicated by the description of the scope of claims, and further, the equivalent meanings described in the scope of claims and all modifications within the scope of the scope of the present invention are included. Including.

  In the wheel bearing device according to the present invention, the inner ring is fixed by a caulking portion formed by press-fitting an inner ring into a small-diameter step portion of a hub wheel and plastically deforming an end portion of the small-diameter step portion. It can be applied to a self-retained wheel bearing device.

It is a longitudinal section showing one embodiment of a wheel bearing device concerning the present invention. It is a principal part enlarged view which shows the hub ring and inner ring | wheel before caulking of FIG. It is a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus.

Explanation of symbols

1 ... inner member 2 ... hub wheels 2a, 3a ... inner rolling surface 2b ... small diameter step 2c ································································································· Chamfered portion 4 ··· Wheel mounting flange 5 ······································································ ··· Seal 10 ··· Outer member 10a ··· Outer rolling surface 10b ····· Body mounting flange 11 ··· Hardened layer 12 ......... Cylindrical portion 12a ......... Bottom surface 13 ......... Round groove 13a, 13b ... Arc surface 51 ...... Hub wheel 51a 52a ... Inner rolling surface 51b ... Small diameter step 1c ································· 52・ Car body mounting flange 54... Ball 55... Wheel mounting flange 56... Hub bolt a. And the dimension b of the large end surface of the inner ring b... Depth r1 of the annular groove... Curvature radius Ri of the chamfered portion of the inner ring, Ro. Radius of curvature of face

Claims (4)

An outer member having a double row outer raceway formed on the inner periphery;
A hub wheel integrally having a wheel mounting flange at one end and a small-diameter step portion extending in the axial direction from the wheel mounting flange, and at least a small-diameter step portion of the hub wheel press-fitted through a predetermined squeezing An inner member formed of one inner ring, and formed on the outer periphery with a double row inner rolling surface facing the double row outer rolling surface;
A double row rolling element that is accommodated so as to roll freely between the rolling surfaces of the inner member and the outer member via a cage,
In the wheel bearing device in which the inner ring is fixed in the axial direction by a caulking portion formed by plastically deforming an end portion of the small diameter step portion radially outwardly,
The end of the small-diameter step portion before caulking is formed as a hollow cylindrical portion, and a large diameter of the inner raceway surface of the inner ring at a depth of 0.5 to 1.0 mm on the outer peripheral surface of the cylindrical portion. An annular groove is formed from the position corresponding to the end beyond the large end surface of the inner ring, and arc surfaces having predetermined radii of curvature Ri and Ro are formed on both sides of the annular groove. The curvature radius Ri of the surface is smaller than the curvature radius Ro of the arc surface on the outer side, and is set in the range of R1 to 10,
A wheel bearing device, wherein a predetermined hardened layer is formed on the small-diameter step portion by induction hardening, and the hardened layer is stopped at a starting point of an outer arc surface in the annular groove.   2. The wheel bearing device according to claim 1, wherein a surface hardness of the hardened layer is set in a range of 50 to 64 HRC, and the caulking portion is left raw with a surface hardness of 25 HRC or less after forging. .   The chamfered portion on the caulking portion side of the inner ring has an arc surface having a predetermined radius of curvature r1, which is smaller than the radius of curvature Ri of the inner arc surface of the annular groove, and is R1.0 to 2.5. The wheel bearing device according to claim 1 or 2, wherein the wheel bearing device is set in a range.   The wheel bearing device according to any one of claims 1 to 3, wherein a depth from a large end surface of the inner ring on the caulking portion side of the cylindrical portion is set smaller than a width of the annular groove.

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