JP5099875B2 - Wheel bearing device - Google Patents

Description

  The present invention relates to a wheel bearing device for rotatably supporting a wheel of an automobile or the like, and more particularly, to increase the bearing rigidity while reducing the weight and size, and to reduce the cost by reducing material loss. It is about.

  2. Description of the Related Art Conventionally, a wheel bearing device for supporting a wheel of an automobile or the like is such that a hub wheel for mounting a wheel is rotatably supported via a rolling bearing, and there are a drive wheel and a driven wheel. For structural reasons, an inner ring rotation method is generally used for driving wheels, and an inner ring rotation method and an outer ring rotation method are generally used for driven wheels. 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. In this double row angular contact ball bearing, a plurality of balls are interposed between a fixed ring and a rotating ring, and a predetermined contact angle is given to the balls so as to contact the fixed ring and the rotating ring.

  Further, the wheel bearing device has a structure called a first generation in which a wheel bearing composed of a double row angular ball bearing or the like is fitted between a knuckle and a hub wheel constituting a suspension device. Second generation structure in which body mounting flange or wheel mounting flange is formed directly on the outer periphery of the member, third generation structure in which one inner rolling surface is directly formed on the outer periphery of the hub wheel, or hub wheel, etc. It is roughly classified into a fourth generation structure in which the inner rolling surface is directly formed on the outer periphery of the outer joint member of the speed universal joint. 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).

  In wheel bearing devices composed of such double-row rolling bearings, the left and right rows of bearings have the same specifications, so that they have sufficient rigidity when stationary, but optimal rigidity is always obtained when the vehicle turns. Absent. That is, the position of the vehicle weight when stationary is determined so that it acts on the approximate center of the double row rolling bearing, but when turning, the opposite side of the turning direction (when turning right, the vehicle Larger radial load or axial load is applied to the left axle. Therefore, at the time of turning, it is effective to increase the rigidity of the outer bearing row rather than the inner bearing row. Then, what is shown in FIG. 4 is known as a bearing device for wheels which achieved high rigidity without enlarging an apparatus.

  This wheel bearing device 50 has a vehicle body mounting flange 51c integrally attached to a knuckle (not shown) on the outer periphery, and an outer side in which double row outer rolling surfaces 51a and 51b are formed on the inner periphery. A member 51 and a wheel mounting flange 53 for mounting a wheel (not shown) at one end are integrally formed, and one inner rolling surface 52a facing the double row outer rolling surfaces 51a and 51b on the outer periphery. The hub wheel 52 having a small-diameter step portion 52b extending in the axial direction from the inner rolling surface 52a and the small-diameter step portion 52b of the hub wheel 52 are externally fitted to the double-row outer rolling surfaces 51a and 51b. An inner member 55 composed of an inner ring 54 formed with the other inner rolling surface 54a facing each other, double rows of balls 56, 57 accommodated between both rolling surfaces, and these double rows of balls 56, 57 A retainer 58 for freely rolling It is composed of a double row angular contact ball bearing with a 9.

  The inner ring 54 is fixed in the axial direction by a caulking portion 52c formed by plastically deforming a small diameter step portion 52b of the hub wheel 52 radially outward. Seals 60 and 61 are attached to the opening of the annular space formed between the outer member 51 and the inner member 55, leakage of the lubricating grease sealed inside the bearing, and rainwater from the outside into the bearing. And dust are prevented from entering.

Here, the pitch circle diameter D1 of the outer side ball 56 is set larger than the pitch circle diameter D2 of the inner side ball 57. Along with this, the inner rolling surface 52a of the hub wheel 52 is expanded in diameter than the inner rolling surface 54a of the inner ring 54, and the outer rolling surface 51a on the outer side of the outer member 51 is also rolled on the inner side. The diameter is larger than that of the surface 51b. The outer side balls 56 are accommodated more than the inner side balls 57. In this way, by setting the pitch circle diameters D1 and D2 to D1> D2, the rigidity is improved not only when the vehicle is stationary but also when turning, and the life of the wheel bearing device 50 can be extended. it can.
JP 2004-108449 A

  In such a conventional wheel bearing device 50, the outer member 51 and the hub wheel 52 are manufactured from a bar material as a raw material through a forging, turning, heat treatment, grinding, superfinishing process, and the like. For example, as shown in FIG. 5, the outer member 51 is formed by forging over both the inner side surface and the inner side surface of the vehicle body mounting flange 51c that contacts the knuckle, from the inner side surface to the inner side surface. The outer shape is formed with a predetermined turning allowance (indicated by a two-dot chain line in the figure).

  Further, in the outer member 51 in which the groove diameters of the double row outer raceway surfaces 51a and 51b are different, when the moment load is applied, the groove shoulder portions 62 and 63 contact the balls 56 and 57. In order to prevent the so-called shoulder climbing that occurs when the ellipse rides up and deviates from the outer rolling surfaces 51a and 51b, it is formed to a predetermined size by turning. In particular, the corner (boundary) between the outer side rolling surface 51b on the inner side and the groove shoulder portion 63 is greatly affected by the moment load because the groove diameter is smaller than that on the outer side rolling surface 51a on the outer side. Since the load may occur, the dimension of the groove shoulder 63 is strictly regulated. Here, the edge load is an excessive stress concentration generated at a corner or the like, and refers to an event that becomes one of the factors of early peeling.

  However, the turning of the groove shoulders 62, 63 and the like in the outer member 51 not only causes material loss but also increases the number of processing steps, which is an obstacle to cost reduction. Furthermore, since the groove shoulder 63 is deleted by punching in the forging process, it has been a problem how to reduce material loss of the material together with the forged shape of the outer member 51.

  The present invention has been made in view of such circumstances, and provides a wheel bearing device that increases the bearing rigidity while reducing the weight and size, and reduces the cost by reducing material loss. It is aimed.

In order to achieve the object, the invention according to claim 1 of the present invention has a vehicle body mounting flange integrally attached to the knuckle on the outer periphery, and a double row outer rolling surface is formed on the inner periphery. An outer member, an inner member provided with a double row inner rolling surface facing the outer row rolling surface of the double row on the outer periphery, and between both rolling surfaces of the inner member and the outer member. A double row rolling element accommodated in a freely rolling manner, and the pitch circle diameter of the outer side rolling element of these double row rolling elements is set larger than the pitch circle diameter of the inner side rolling element. In the wheel bearing device, a shoulder portion adjacent to each of the double row outer rolling surfaces is formed, and the shoulder portion on the large diameter side has a small inclination angle due to a draft angle of forging to the vicinity of the base portion of the vehicle body mounting flange. a tapered surface, removal from the stepped portion the forging between the shoulder portion of the shoulder portion and the large diameter side of the small diameter side Together are formed in the tapered surface of the larger angle of inclination than the distribution, front shoulder of the Kidan portion and the large diameter side is left forging skin, the shoulder of the small-diameter side to a predetermined inner diameter by turning Is formed .

As described above, the wheel bearing device of the second to fourth generation structure in which the pitch circle diameter of the outer side rolling element of the double row rolling elements is set larger than the pitch circle diameter of the inner side rolling element. The shoulders adjacent to the double-row outer rolling surfaces are formed, and the shoulders on the large diameter side are formed on the tapered surface with a small inclination angle due to the draft angle of forging up to the vicinity of the base of the body mounting flange. with the stepped portion between the shoulder portion of the side of the shoulder portion and the large diameter side is formed in a tapered surface of the larger angle of inclination than the draft of the forging, the shoulder portion of the stepped portion and the large diameter side and leave forging skin Since the shoulder on the small diameter side is formed to a predetermined inner diameter by turning, material loss can be reduced without reducing the strength and rigidity of the outer member, and the material in the forging process can be reduced. To improve plastic flow and improve processing accuracy Kill. Furthermore, punching can be facilitated and the number of man-hours can be reduced, and the material to be deleted can be reduced as much as possible to reduce material loss, thereby reducing costs.

  Preferably, as in the invention according to claim 2, the size of the double row rolling elements is the same, and the number of the outer side rolling elements is set to be larger than the number of the inner side rolling elements. As a result, the bearing life can be ensured while achieving high rigidity.

Further, as in the invention described in claim 3 , the inner member has one inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and a shaft-shaped portion from the inner rolling surface. Through which a small-diameter step portion extending in the axial direction is formed, and the other inner rolling surface which is press-fitted into the small-diameter step portion of the hub wheel and faces the double-row outer rolling surface is formed on the outer periphery. A mortar-shaped recess is formed at the outer side end of the hub wheel, and the depth of the recess is at least near the groove bottom of the inner raceway surface of the hub wheel. The outer shape of the ring is formed so as to have a substantially uniform thickness corresponding to the recess, and the counter portion of the inner rolling surface is formed in a cylindrical shape, and the counter portion and the shaft shape are formed. The step portion connecting the portions is formed in an arc shape or a taper shape, and the shaft portion and the step portion are left as forged skin. Put it, it is possible to reduce the material losses without reducing the strength and rigidity of the wheel hub to increase the plastic flow of the material in the forging process, it is possible to improve the machining accuracy.

A wheel bearing device according to the present invention has a body mounting flange integrally attached to a knuckle on an outer periphery, an outer member having a double row outer raceway formed on an inner periphery, and the compound member on an outer periphery. An inner member provided with a double row inner rolling surface facing the outer rolling surface of the row, and a double row accommodated in a freely rollable manner between both rolling surfaces of the inner member and the outer member In the wheel bearing device, the pitch circle diameter of the outer side rolling elements among these double row rolling elements is set larger than the pitch circle diameter of the inner side rolling elements. A shoulder portion adjacent to each outer rolling surface of the row is formed, and a shoulder portion on the large diameter side is formed into a tapered surface having a small inclination angle by a forging draft to the vicinity of the base portion of the vehicle body mounting flange . It stepped portion between the shoulder of the shoulder portion and the large diameter side of the large tilt angle than the draft of the forging Together are formed by over tapered surface, the shoulder portion of the front Kidan portion and the large diameter side is left forged skin, since the shoulder portion of the smaller-diameter side is formed in a predetermined inner diameter by turning, outer The material loss can be reduced without reducing the strength and rigidity of the rectangular member, the plastic fluidity of the material in the forging process can be increased, and the processing accuracy can be improved. Furthermore, punching can be facilitated and the number of man-hours can be reduced, and the material to be deleted can be reduced as much as possible to reduce material loss, thereby reducing costs.

A body mounting flange for mounting to the knuckle on the outer periphery is integrated, an outer member with a double row outer raceway formed on the inner periphery, and a wheel mounting flange for mounting the wheel on one end is integrated. A hub wheel having one inner rolling surface facing the outer rolling surface of the double row on the outer periphery, a small diameter step portion extending in the axial direction from the inner rolling surface, and a small diameter of the hub wheel An inner member consisting of an inner ring that is press-fitted into a stepped portion and has the other inner rolling surface facing the outer rolling surface of the double row on the outer periphery, and both rolling of the inner member and the outer member A double row rolling element accommodated so as to roll freely between the surfaces, and the pitch circle diameter of the outer side rolling element of these double row rolling elements is larger than the pitch circle diameter of the inner side rolling element. And the size of the rolling elements in the double row is the same, the outer side In the wheel bearing device is set larger than the number of rolling elements of the number is the inner side of the body, each adjacent shoulder portion is formed on the outer rolling run surfaces of the double row, shoulder portion of the large diameter side , Formed near the base of the body mounting flange on a tapered surface with a small inclination angle due to the draft of forging, and the step between the shoulder on the small diameter side and the shoulder on the large diameter side is larger than the draft of the forging together are formed in the tapered surface of the inclination angle, the shoulder portion of the front Kidan portion and the large diameter side is left forging skin, the shoulder of the small-diameter side is formed in a predetermined inner diameter by turning.

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, FIG. 2 (a) is an explanatory view showing a forged shape of the outer member of FIG. 1, and FIG. explanatory view showing a reference example of), FIG. 3 is an explanatory view showing a forging shape of the hub of Figure 1.

  This wheel bearing device is for a driven wheel referred to as a third generation, and is a double row rolling element housed in a freely rollable manner between the inner member 1 and the outer member 2, and both members 1 and 2. (Balls) 3 and 3. The inner member 1 includes a hub ring 4 and an inner ring 5 press-fitted into the hub ring 4 through a predetermined shimiro.

  The hub wheel 4 integrally has a wheel mounting flange 6 for mounting a wheel (not shown) at an end portion on the outer side, and has one (outer side) inner rolling surface 4a on the outer periphery and the inner rolling surface. A small-diameter step portion 4b is formed through a shaft-like portion 7 extending in the axial direction from the surface 4a. Hub bolts 6a are implanted in the wheel mounting flange 6 in a circumferentially equal distribution, and circular holes 6b are formed between the hub bolts 6a. The circular hole 6b can not only contribute to weight reduction, but also a fastening jig such as a wrench can be inserted from the circular hole 6b in the assembly / disassembly process of the apparatus, and the work can be simplified.

  The inner ring 5 is formed with the other (inner side) inner raceway surface 5a on the outer periphery and is press-fitted into the small-diameter stepped portion 4b of the hub wheel 4 to form a back-to-back type double row angular contact ball bearing. The inner ring 5 is fixed in the axial direction by a caulking portion 8 formed by plastic deformation of the end portion of 4b. The inner ring 5 and the rolling element 3 are made of high carbon chrome steel such as SUJ2, and are hardened in the range of 58 to 64 HRC to the core part by quenching.

  The hub wheel 4 is made of medium and high carbon steel containing 0.40 to 0.80 wt% of carbon, such as S53C, and the inner raceway surface 4a and the base portion 6c on the inner side of the wheel mounting flange 6 to the small diameter step portion 4b. Thus, the surface hardness is set to a range of 58 to 64 HRC by induction hardening. The caulking portion 8 is kept in the surface hardness after forging. Thereby, it has sufficient mechanical strength with respect to the rotational bending load applied to the wheel mounting flange 6, the fretting resistance of the small-diameter step portion 4b serving as the fitting portion of the inner ring 5 is improved, and the minute There is no occurrence of cracks and the like, and the plastic working of the caulking portion 8 can be performed smoothly.

  The outer member 2 integrally has a vehicle body mounting flange 2c to be attached to a knuckle (not shown) on the outer periphery, and the outer side outer rolling facing the inner rolling surface 4a of the hub wheel 4 on the inner periphery. The surface 2a and the inner side outer rolling surface 2b facing the inner rolling surface 5a of the inner ring 5 are integrally formed. Double-row rolling elements 3 and 3 are accommodated between these rolling surfaces and are held by the cages 9 and 10 so as to roll freely.

This outer member 2 is made of medium and high carbon steel containing 0.40 to 0.80 wt% of carbon such as S53C, and the double row outer rolling surfaces 2a and 2b have a surface hardness in the range of 58 to 64HRC by induction hardening. Has been cured. Seals 11 and 12 are attached to the opening of the annular space formed between the outer member 2 and the inner member 1, and leakage of grease sealed inside the bearing and rainwater from the outside. And dust are prevented from entering the bearing. In addition, although the double row angular contact ball bearing which used the ball for the rolling element 3 was illustrated here, not only this but the double row tapered roller bearing which uses the tapered roller for the rolling element 3 may be sufficient. In addition, the second generation or the fourth generation structure is not limited to the third generation structure on the driven wheel side.

  In this embodiment, the pitch circle diameter PCDo of the outer side rolling element 3 is set larger than the pitch circle diameter PCDi of the inner side rolling element 3. The sizes of the double-row rolling elements 3 and 3 are the same, but due to the difference in pitch circle diameters PCDo and PCDi, the number of outer-side rolling elements 3 is set larger than the number of inner-side rolling elements 3. Has been.

  The outer shape of the hub wheel 4 is such that the counter portion 13 from the groove bottom portion of the inner rolling surface 4a, the shaft-like portion 7 extending in the axial direction from the counter portion 13 via the arc-shaped step portion 7a, and the inner ring 5 protrude. It continues to the small diameter step part 4b through the shoulder part 7b fitted together. A mortar-shaped recess 14 is formed at the outer end of the hub wheel 4. The depth of the recess 14 is a depth to the vicinity of the groove bottom of the inner rolling surface 4a, and the outer side of the hub wheel 4 is formed to have a substantially uniform thickness. The inner raceway surface 4a of the hub wheel 4 is formed to have a larger diameter than the inner raceway surface 5a of the inner ring 5 in accordance with the difference between the pitch circle diameters PCDo and PCDi.

  On the other hand, in the outer member 2, the outer side outer rolling surface 2a is formed with a larger diameter than the inner side outer rolling surface 2b due to the difference in pitch circle diameters PCDo and PCDi, and the outer side outer rolling surface 2b is formed. From the running surface 2a through the cylindrical shoulder portion 15 and the tapered step portion 15a to the shoulder portion 16 on the small diameter side, the outer rolling surface 2b on the inner side is reached.

  In the wheel bearing device having such a configuration, the pitch circle diameter PCDo of the outer side rolling element 3 is formed larger than the pitch circle diameter PCDi of the inner side rolling element 3, and the number of the rolling elements 3 is also increased accordingly. Since the number of sides is set to be larger than the number of inner sides, it is possible to effectively increase the bearing rigidity of the outer side compared to the inner side by utilizing the bearing space, and to extend the life of the bearing. Can do. Furthermore, since the recess 14 is formed along the outer shape at the outer end of the hub wheel 4 and the outer side of the hub wheel 4 is set to a uniform thickness, the device is lighter, more compact and more rigid. It is possible to solve the conflicting problem.

  Here, the outer member 2 is formed into a predetermined forging shape as shown in FIG. 2A by forging from a bar material as a raw material (indicated by a two-dot chain line in the figure). That is, the inner side surface 17 of the vehicle body mounting flange 2c with which the knuckle (not shown) abuts, the inner side outer peripheral surface 18 on which the knuckle is fitted, the both end surfaces 19 and 20, and the seals 11 and 12 are mounted. The seal fitting surfaces 21 and 22, the double-row outer rolling surfaces 2a and 2b, and the shoulder 16 on the small diameter side are forged while leaving a predetermined turning allowance.

  In the present embodiment, in order to reduce material loss in the forging process, the shoulder 15 on the large diameter side is formed on a tapered surface with a relatively small inclination angle by the forging draft to the vicinity of the base of the vehicle body mounting flange 2c. At the same time, the width dimension of the shoulder portion 16 on the small diameter side is minimized, and the step portion 15a between the shoulder portion 16 on the small diameter side and the shoulder portion 15 on the large diameter side has a predetermined inclination angle, that is, a draft angle of forging. Compared to a tapered surface having a larger inclination angle. Thereby, while being able to aim at reduction of material loss, without reducing the intensity | strength and rigidity of the outer member 2, the plastic fluidity | liquidity of the raw material in a forge process can be improved, and a processing precision can be improved. Furthermore, punching can be facilitated and the number of man-hours can be reduced, and the material to be deleted can be reduced as much as possible to reduce material loss, thereby reducing costs.

  On the other hand, the shoulder 16 on the small diameter side is formed to have a predetermined inner diameter by turning after the forging process, but the shoulder 15 and the step portion 15a on the large diameter side are abolished and left as a forged skin. ing. As a result, material loss can be further reduced, the number of turning processes can be reduced, and cost can be reduced.

The outer member 2 ′ shown in FIG. 2 (b) shows a reference example of FIG. 2 (a). However, the outer member 2 ′ has a large diameter from the cylindrical shoulder portion 16 on the small diameter side through a step portion 23a having an arc surface. The side shoulder 23 is formed with a tapered surface having a predetermined inclination angle. Thereby, the plastic fluidity of the raw material in the forging process can be further increased, and the processing accuracy can be improved.

  The hub wheel 4 is formed into a predetermined forged shape as shown in FIG. 3 by forging from a bar material as a raw material (indicated by a two-dot chain line in the figure) in the same manner as the outer member 2 described above. That is, the outer side surface 24 and the pilot portion 25 of the wheel mounting flange 6 with which the brake rotor (not shown) abuts, the base portion 6c of the wheel mounting flange 6, the inner rolling surface 4a, the counter portion 13, and the small diameter Forging is performed with the stepped portion 4b leaving a predetermined turning allowance.

  In the present embodiment, the counter portion 13 is formed in a cylindrical shape, and a step portion 7 a that connects the counter portion 13 and the shaft-like portion 7 is formed in an arc shape. Thereby, while being able to aim at reduction of material loss, without reducing the intensity | strength and rigidity of the hub ring | wheel 4, the plastic fluidity | liquidity of the raw material in a forge process can be improved, and a processing precision can be improved. The counter portion 13 is formed into a predetermined shape and size by turning after the forging process, but the shaft-like portion 7 and the stepped portion 7a are abolished and left as a forged skin. As a result, material loss can be further reduced, the number of turning processes can be reduced, and cost can be reduced. The step portion 7a is not limited to an arc shape, and may be formed in a tapered shape having a predetermined inclination angle. Furthermore, in this embodiment, a step portion having a predetermined inclination angle is formed between the shoulder portion on the small diameter side and the shoulder portion on the large diameter side. The shoulder part which consists of one taper surface may be sufficient.

  As described above in detail, in the present embodiment, the outer member 2 and the hub wheel 4 are formed in a forged shape with improved plastic fluidity without reducing strength and rigidity, so that the forging processing accuracy is improved. It can be improved and the number of turning parts can be reduced to the minimum necessary, and material costs and the number of turning processes can be reduced, thereby achieving cost reduction.

  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.

Wheel bearing device according to the present invention, the driving wheels, regardless of the follower wheel, can be applied to a wheel bearing apparatus of the second to fourth generation type.

It is a longitudinal section showing one embodiment of a wheel bearing device concerning the present invention. (A) is explanatory drawing which shows the forge shape of the outward member of FIG. (B) is explanatory drawing which shows the reference example of (a). It is explanatory drawing which shows the forge shape of the hub ring of FIG. It is a longitudinal cross-sectional view which shows the conventional wheel bearing apparatus. It is explanatory drawing which shows the forge shape of an outward member same as the above.

Explanation of symbols

1 ... Inner member 2, 2 '... Outer member 3 ... Rolling element 4 ... ····························································································································・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Wheel mounting flange 6a ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Hub bolt 6b ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ Circular hole 6c ・ ・ ・ ・ ・ ・ ・ ・ ・ ・Base 7 ... Shaft 7a, 15a, 23a ... Step 7b ... Shoulder 8 ... Caulking parts 9, 10 ... Cage 11, 12, ... Seal 13 ... Counter part 14 ...・ Recesses 15, 23... Large diameter side shoulder 16... Small diameter side shoulder 17. .... Inner side surface 18 of the vehicle body mounting flange ... Outer member outer peripheral surfaces 19 and 20 ... Outer member end face 21, 22 ······· Seal fitting surface 24 ··· Side surface 25 on outer side of wheel mounting flange ··· Pilot portion 50 ··· .... Wheel bearing device 51 ... Outer member 51a ... Outer rolling surface 51b on the outer side ··· Outer rolling surface 51c on the inner side ······· Body mounting flange 52 ·················· Hub wheels 52a, 54a ··· Inner rolling surface 52b ······ Small diameter step 52c ················································ Wheel mounting flange 54 ··· ..... Inner members 56, 57 ..... Balls 58, 59 ..... Retainer 60, 61 ..... Seals 62, 63. ········ Ditch shoulder D1 ········· Pitch circle diameter D2 of the outer side ball ········· Pitch circle diameter PCDi of the inner side ball .... Pitch circle diameter of the inner rolling element PCDo ... Pitch circle diameter of the outer rolling element

Claims (3)

An outer member (2) integrally having a vehicle body mounting flange (2c) to be attached to the knuckle on the outer periphery, and having a double row outer rolling surface (2a, 2b) formed on the inner periphery;
An inner member (1) provided with a double-row inner rolling surface (4a, 5a) opposite to the double-row outer rolling surface (2a, 2b) on the outer periphery;
A double row rolling element (3, 3) accommodated between the rolling surfaces of the inner member (1) and the outer member (2) so as to roll freely;
Of these double-row rolling elements (3, 3), the pitch circle diameter (PCDo) of the outer rolling element (3) is set larger than the pitch circle diameter (PCDi) of the inner rolling element (3). In a wheel bearing device,
Shoulder portions (15, 16) adjacent to the double row outer rolling surfaces (2a, 2b) are formed, and the shoulder portion (15) on the large diameter side extends to the vicinity of the base portion of the vehicle body mounting flange (2c). It is formed on a tapered surface with a small inclination angle due to the draft angle of forging, and the step (15a) between the shoulder portion (16) on the small diameter side and the shoulder portion (15) on the large diameter side is larger than the draft angle of the forging. The step portion and the large-diameter side shoulder portion are left as forged skin, and the small-diameter side shoulder portion (16) is formed into a predetermined inner diameter dimension by turning. A wheel bearing device characterized by comprising:   The size of the double row rolling elements (3, 3) is the same, and the number of the outer side rolling elements (3) is set larger than the number of the inner side rolling elements (3). The wheel bearing apparatus described in 1. The inner member (1) has one inner rolling surface (4a) opposed to the double row outer rolling surface (2a, 2b) on the outer periphery, and a shaft-shaped portion from the inner rolling surface (4a). The hub wheel (4) formed with a small-diameter step portion (4b) extending in the axial direction via (7) and the small-diameter step portion (4b) of the hub wheel (4) are press-fitted, and the double row is inserted into the outer periphery. Consists of an inner ring (5) formed with the other inner rolling surface (5a) opposite to the outer rolling surface (2a, 2b), and a mortar-shaped recess at the outer end of the hub wheel (4) A recess (14) is formed, and the depth of the recess (14) is at least near the groove bottom of the inner raceway surface (4a) of the hub wheel (4), and the outer shape of the hub wheel (4) is The counter portion (13) of the inner rolling surface (4a) is cylindrical, and is formed to have a substantially uniform thickness corresponding to the recess (14). A step portion (7a) connecting the counter portion (13) and the shaft-like portion (7) is formed in an arc shape or a taper shape, and the shaft-like portion (7) and the step portion (7a) are formed. There wheel bearing apparatus of claim 1 or 2 is kept forging skin.

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