Wheel bearing device and method for producing same

Abstract

Among tooth tips 53 of a hub-side face spline 52 that is provided to a crimp portion 22, a top portion 53e which is disposed on the most inboard side is disposed further toward the outer diameter side than an inner peripheral surface 17a of an inner ring 17. With this configuration, the height of the tooth tips 53 of the hub-side face spline 52 is ensured and the contact area with a coupling-side face spline 51 is ensured. Thus, the strength and durability of fitting portions of both the face splines 51, 52 are enhanced.

Description

Wheel Bearing Unit and Method for Manufacturing the Same

[0001] The present invention relates to a wheel bearing unit for supporting a wheel with respect to a vehicle body in a vehicle such as an automobile, and a method for manufacturing the same.

[0002] As a wheel bearing unit in which a double-row rolling bearing (wheel bearing) and a constant velocity joint are unitized, torque transmission between a hub ring and an outer joint member of the constant velocity joint is performed via face splines provided on end faces of the hub ring and the outer joint member that face each other in the axial direction. Such a structure is known.

[0003] Patent Document 1 below discloses a method for forming a face spline on an end face of a hub ring. Specifically, as shown in FIG. 11, after assembling an inner ring 107, an outer member 104, rolling elements 106, and a cage 108 on the outer periphery of a hub ring 101, a punch 128 is pressed against an inboard-side end portion 131 (upper end in the figure) of a cylindrical portion 130 of the hub ring 101, and the hub ring 101 is swung about an axis L of the hub ring 101. By doing so, the inboard-side end portion 131 of the cylindrical portion 130 is caulked to the outer diameter side to form a caulked portion 110. At the same time, a tooth shape 127 provided on the punch 128 is pressed against the caulked portion 110 to form a face spline 119 on the end face of the caulked portion 110.

[0004] Further, in Patent Document 2 below, the caulked portion is formed in two steps. Specifically, in the first step, the inboard-side end portion of the cylindrical portion is expanded to the outer diameter side, and in the subsequent second step, the inboard-side end portion of the cylindrical portion is further expanded to the outer diameter side to form a caulked portion, and a face spline is formed on the end face of the caulked portion.

[0005] Japanese Patent No. 5261023 Japanese Unexamined Patent Application Publication No. 2011 - 31682

[0006] In the method shown in Figure 11, the tooth tips of the tooth profile 127 of the punch 128 are pressed against the end face of the crimping portion 110 to form grooves (tooth roots) of the face spline 119, and the material of the crimping portion 110 undergoes plastic flow and enters the valleys of the tooth profile 127 to form grooves (tooth tips) of the face spline 119. At this time, it is difficult to fill the entire radial area of ​​the face spline 119 with material up to the tooth roots of the tooth profile 127 of the punch 128, so the outer diameter portion of the face spline 119 is not filled up to the tooth roots of the tooth profile 127, which can cause sagging of the outer diameter portion of the tooth tip.

[0007] In particular, as described in Patent Document 2 above, when the crimping process is divided into two stages, a first and a second step, and the face spline is formed in the second step, there is a tendency for the burring of the outer diameter portion of the tooth tip of the face spline to increase. When the burring of the tooth tip of the face spline in the crimped portion increases, the surface area of ​​the tooth decreases, and the contact area with the face spline on the constant velocity universal joint side decreases, leading to a decrease in the strength and durability of the spline fitting portion.

[0008] Therefore, the present invention aims to improve the strength and durability of the fitting portion between the face splines of the crimped portion of the hub wheel and the face splines of the outer joint member of the constant velocity universal joint.

[0009] To solve the above problems, the present invention provides a wheel bearing device comprising a wheel bearing and a constant velocity universal joint provided on the inboard side of the wheel bearing, wherein the wheel bearing comprises an outer member having double rows of outer raceway surfaces formed on its inner circumference, an inner member having double rows of inner raceway surfaces formed on its outer circumference, and a plurality of rolling elements disposed between the opposing inner raceway surfaces and the outer raceway surfaces, the inner member comprises a hub ring having a cylindrical portion and an inner ring fitted to the outer circumference of the cylindrical portion and having the inner raceway surface on the inboard side, a crimping portion is provided at the inboard side end of the cylindrical portion of the hub ring which is bent toward the outer diameter side and contacts the inboard side end face of the inner ring, the constant velocity universal joint comprises an outer joint member fixed to the inner member, and face splines are formed on the outer joint member and the crimping portion that face each other in the axial direction and mesh in a manner that enables torque transmission. The present invention provides a wheel bearing device in which the tip of the tooth of the face spline of the crimped portion, the tip that is positioned furthest inboard, is positioned on the outer diameter side of the inner circumferential surface of the inner ring.

[0010] In this way, by positioning the tip of the tooth of the crimping portion's face spline (hereinafter also referred to as the "hub-side face spline") that is closest to the inboard side, on the outer diameter side of the inner ring's circumferential surface, it is possible to secure the axial height (distance from the tooth root) near the outer diameter end of the tooth tip of the hub-side face spline. As a result, the contact area between the hub-side face spline and the constant velocity universal joint side's face spline (hereinafter also referred to as the "joint-side face spline") is secured, thereby increasing the strength and durability of the mating portion of both face splines.

[0011] In the above-described wheel bearing device, it is preferable to position the tips of the teeth of the hub-side face splines on the outer diameter side of the radial center between the inner circumferential surface of the inner ring and the outer diameter end of the crimped portion.

[0012] When forming a hub-side face spline by pressing a tooth profile against a crimping section, it is difficult to fill the entire radial area of ​​the hub-side face spline to the tooth root of the tooth profile. Of the tooth tips of the hub-side face spline, the inner diameter portion is provided with a dense surface formed by the tooth root of the tooth profile, while the outer diameter portion is not formed by the tooth root of the tooth profile, resulting in a rough surface with a rougher surface than the dense surface. In this case, the tooth tip of the hub-side face spline is provided with a dense surface and a rough surface provided on the outer diameter side of the dense surface, with the apex of the tooth tip located on this rough surface.

[0013] Since the cross-section (a section perpendicular to the radial direction) of the protrusions of the hub-side face spline is substantially trapezoidal, when the axial height of the outer diameter portion of the tooth tip of the hub-side face spline decreases, the circumferential width of the tooth tip increases. Therefore, for example, it is preferable to ensure sufficient axial height on the rough surface of the tooth tip so that the circumferential width at the radial center of the rough surface of the tooth tip of the hub-side face spline is 1.2 times or less than the circumferential width at the radial center of the fine surface.

[0014] Furthermore, the present invention relates to a method for manufacturing a wheel bearing device comprising a wheel bearing and a constant velocity universal joint provided on the inboard side of the wheel bearing, wherein the wheel bearing comprises an outer member having double rows of outer raceway surfaces formed on its inner circumference, an inner member having double rows of inner raceway surfaces formed on its outer circumference, and a plurality of rolling elements disposed between the opposing inner raceway surfaces and the outer raceway surfaces, the inner member comprises a hub ring having a cylindrical portion and an inner ring fitted to the outer circumference of the cylindrical portion and having the inner raceway surface on the inboard side, a crimping portion is provided at the inboard side end of the cylindrical portion of the hub ring which is bent toward the outer diameter and contacts the inboard side end face of the inner ring, the constant velocity universal joint comprises an outer joint member fixed to the inner member, face splines are formed on the outer joint member and the crimping portion which face each other in the axial direction and mesh in a torque-transmitting manner, and when forming the crimping portion at the inboard side end of the cylindrical portion of the hub ring and forming the face splines on the end face of the crimping portion, The present invention provides a method for manufacturing a wheel bearing device, wherein the tip of the tooth of the face spline of the crimped portion that is positioned furthest inboard is positioned on the outer diameter side of the inner circumferential surface of the inner ring.

[0015] The above manufacturing method may include a first crimping step of expanding the diameter of the inboard end of the cylindrical portion of the hub wheel without forming a face spline, and a second crimping step of further expanding the diameter of the inboard end of the cylindrical portion of the hub wheel to form a crimped portion, while forming a face spline on the end face of this crimped portion.

[0016] In the above manufacturing method, it is preferable that the reduction in the axial dimension of the cylindrical portion due to the first crimping step is smaller than the reduction in the axial dimension of the cylindrical portion due to the second crimping step. By reducing the amount of processing (plastic deformation) in the first crimping step, which does not form face splines, and increasing the amount of processing (plastic deformation) in the second crimping step, which forms face splines, it becomes easier to fill the outer diameter portion of the face splines all the way to the tooth roots of the tooth profile.

[0017] In the above manufacturing method, it is preferable to crimp the cylindrical portion of the hub ring while constraining it from the inner diameter side during the second crimping step. By actively causing the material of the cylindrical portion to flow outward while restricting its flow inward, it becomes easier to fill the outer diameter portion of the face spline all the way to the tooth root of the mold.

[0018] As described above, according to the present invention, the strength and durability of the fitting portion between the face splines of the crimped portion of the hub wheel and the face splines of the outer joint member of the constant velocity universal joint can be increased.

[0019] This is an axial cross-sectional view of a wheel bearing device according to one embodiment of the present invention. This is a front view of the hub-side face spline as seen from the inboard side. This is a perspective view of the hub-side face spline. The upper figure is an axial cross-sectional view at the circumferential center of the convex ridge of the hub-side face spline (line X-X in Figure 2), and the lower figure is an axial cross-sectional view at the circumferential center of the concave ridge of the hub-side face spline (line Y-Y in Figure 2). This is an enlarged view of the upper figure in Figure 4. This is a circumferential cross-sectional view at the radial center of the second region (dense surface) of the tooth tip of the hub-side face spline. This is a circumferential cross-sectional view at the radial center of the third region (rough surface) of the tooth tip of the hub-side face spline. This is a cross-sectional view showing the state before crimping (dotted line), the state after the first crimping process (solid line), and the state after the second crimping process (dashed line) near the inboard side end of the cylindrical portion of the hub ring. This is a cross-sectional view showing the second crimping process. This is a cross-sectional view showing the second crimping process according to another embodiment. This is a cross-sectional view showing a conventional crimping process.

[0020] Hereinafter, embodiments of the present invention will be described based on the drawings.

[0021] As shown in Figure 1, a wheel bearing device 1 according to one embodiment of the present invention has a structure in which a wheel bearing 2 and a constant velocity universal joint 3 are unitized. In the following description, the direction of the axis L of the wheel bearing device 1 will be referred to as the "axial direction," and in the axial direction, the direction that is on the outside in the vehicle width direction when mounted on the vehicle body (left side in Figure 1) will be referred to as the outboard side, and the direction that is on the inside in the vehicle width direction (right side in Figure 1) will be referred to as the inboard side.

[0022] The wheel bearing 2 mainly consists of an inner member 7 having double rows of inner raceway surfaces 5 and 6, an outer member 12 positioned on the outer diameter side of the inner member 7 and having double rows of outer raceway surfaces 10 and 11, a plurality of rolling elements 13 positioned between the radially opposing inner raceway surfaces 5 and 6 and the outer raceway surfaces 10 and 11, and a cage 14 that holds the rolling elements 13 at equal intervals in the circumferential direction. In the illustrated example, the rolling elements 13 are balls. Note that the rolling elements may be cylindrical rollers or tapered rollers, for example.

[0023] The outer member 12 has a cylindrical portion 12a with outer raceway surfaces 10 and 11 formed on its inner circumference, and a body mounting flange 12b that protrudes outward from the cylindrical portion 12a. The body mounting flange 12b is fixed to the knuckle of the vehicle body by bolts.

[0024] The inner member 7 has a hub wheel 16 and an inner ring 17 fixed to the outer circumference of the hub wheel 16. Of the two rows of inner raceway surfaces 5 and 6, the inner raceway surface 5 on the outboard side is formed on the outer circumference of the hub wheel 16, and the inner raceway surface 6 on the inboard side is formed on the outer circumference of the inner ring 17.

[0025] The hub wheel 16 has a cylindrical portion 21 and a wheel mounting flange 18 that protrudes outward from the cylindrical portion 21. In the illustrated example, the cylindrical portion 21 and the wheel mounting flange 18 are integrally formed. The cylindrical portion 21 has a through hole 24 that penetrates axially. The wheel and brake rotor are fixed to the wheel mounting flange 18 by bolts fitted into bolt mounting holes 20 of the wheel mounting flange 18. An inner ring 17 is press-fitted and fixed to the outer circumferential surface near the inboard end of the cylindrical portion 21. A crimped portion 22 that is bent outward is provided at the inboard end of the cylindrical portion 21. The crimped portion 22 is formed by crimping the inner ring 17 after press-fitting it into the cylindrical portion 21 (details will be described later). The crimped portion 22 is in contact with the inboard end surface of the inner ring 17. This crimped portion 22 positions the inner ring 17 and applies a predetermined preload inside the wheel bearing 2. A bolt member 26, which serves as a connecting member for linking the wheel bearing 2 and the constant velocity universal joint 3, is inserted from the outboard side into the through hole 24 of the hub wheel 16.

[0026] The constant velocity universal joint 3 is provided on the inboard side of the wheel bearing 2. The constant velocity universal joint 3 is a fixed type constant velocity universal joint that allows only angular displacement and does not allow axial displacement. The constant velocity universal joint 3 comprises an outer joint member 31 having a cup-shaped mouth portion 30, an inner joint member 32 housed on the inner diameter side of the mouth portion 30 of the outer joint member 31, and a ball 33 as a torque transmission member disposed between the inner joint member 32 and the outer joint member 31. A female spline 34 is formed on the inner circumferential surface of the central hole of the inner joint member 32, and a male spline formed on the end of an intermediate shaft (not shown) is inserted into this female spline 34. As a result, the inner joint member 32 and the intermediate shaft are coupled in a torque transmission manner.

[0027] Multiple track grooves 35 extending in the axial direction are formed at multiple locations in the circumferential direction on the spherical inner surface of the mouse portion 30, and multiple track grooves 36 extending in the axial direction are formed at multiple locations in the circumferential direction on the spherical outer surface of the inner joint member 32. The track grooves 35 of the outer joint member 31 and the track grooves 36 of the inner joint member 32, which face each other radially, form pairs, and one ball 33 is rotatably incorporated into each of the multiple ball tracks formed by the pair of track grooves 35, 36. Each ball 33 is held in an equally spaced position in the circumferential direction by a cage 37. The spherical outer surface of the cage 37 is in contact with the spherical inner surface of the outer joint member 31, and the spherical inner surface of the cage 37 is in contact with the spherical outer surface of the inner joint member 32.

[0028] The mouse portion 30 has a bottom portion 39 on which a female thread portion 38 is formed centered on the axis. By screwing the male thread portion 27 formed at the tip of the bolt member 26 into the female thread portion 38, the seating surface 26a of the bolt member 26 engages with the outboard side end face 16a of the hub wheel 16 in the axial direction. Further screwing in the bolt member 26 applies an axial tightening force between the outer joint member 31 and the hub wheel 16 in a direction that brings them closer together.

[0029] A torque transmission section 50 is provided between the inner member 7 of the wheel bearing 2 and the bottom 39 of the mouth portion 30 of the outer joint member 31. This torque transmission section 50 is configured to engage a joint-side face spline 51 formed on the constant velocity universal joint 3 with a hub-side face spline 52 formed on the hub wheel 16. In this embodiment, the joint-side face spline 51 is formed on the outboard end face of the bottom 39 of the mouth portion 30 of the outer joint member 31, and the hub-side face spline 52 is formed on the inboard end face of the crimping portion 22 of the hub wheel 16.

[0030] As shown in Figures 2 and 3, the hub-side face spline 52 has a configuration in which multiple radially extending protrusions and multiple radially extending recesses are arranged alternately in the circumferential direction. Although not shown in the figures, the joint-side face spline 51 also has a configuration similar to the hub-side face spline 52, in which multiple radially extending protrusions and multiple radially extending recesses are arranged alternately in the circumferential direction. By engaging the joint-side face spline 51 and the hub-side face spline 52, and further screwing the bolt member 26 into the female thread portion 38, an axial tightening force is applied between the two face splines 51 and 52, thereby connecting the outer joint member 31 and the hub wheel 16 in a torque-transmitting manner.

[0031] As shown in the upper part of Figure 4 and in Figure 5, the inboard end face (tooth tip 53) of the protrusions of the hub-side face spline 52 is gradually displaced inboard as it moves from the inner diameter end to the outer diameter side, and once it exceeds the apex 53e which is located furthest inboard, it is displaced outboard as it moves towards the outer diameter side. More specifically, as shown in Figures 3 and 5, the tooth tip 53 of the hub-side face spline 52 is provided with a first region 53a, a second region 53b, a third region 53c, and a fourth region 53d, in order from the inner diameter side.

[0032] The first to third regions 53a to 53c are displaced towards the inboard side toward the outer diameter side. The first to third regions 53a to 53c are approximately parallel to the axial direction at the inner diameter end, and approach the direction J perpendicular to the axial direction as they approach the top portion 53e.

[0033] In the illustrated example, the first region 53a is approximately parallel to the axial direction at the inner diameter end, and forms a curved surface in which the angle with respect to the axial direction increases as it moves from the inner diameter end towards the outer diameter (see Figures 3 and 5). The second region 53b forms a cylindrical surface extending in the radial direction (see Figure 3), and more specifically, it forms a cylindrical surface extending in a direction inclined toward the inboard side toward the outer diameter (see Figure 5). The angle of the second region 53b with respect to the axial direction is equivalent to the angle of the first region 53a with respect to the axial direction at the outer diameter end. The third region 53c forms a substantially planar surface (see Figure 3) and extends in a direction inclined toward the inboard side toward the outer diameter (see Figure 5). The angle of the third region 53c with respect to the axial direction is greater than the angle of the second region 53b with respect to the axial direction (closer to the direction J perpendicular to the axial direction).

[0034] The fourth region 53d is displaced outboard toward the outer diameter and extends to the outer diameter end 22a of the crimping portion 22. In the illustrated example, the fourth region 53d has a substantially flat portion that is inclined outboard toward the outer diameter and a curved portion that smoothly connects the substantially flat portion with the outer diameter end (top 53e) of the third region 53c and the outer diameter end 22a of the crimping portion 22 (see Figures 3 and 5).

[0035] The tip 53e of the tooth 53 is located at the boundary between the third region 53c and the fourth region 53d. The tip 53e is positioned on the outer diameter side of the inner circumferential surface 17a of the inner ring 17. In the illustrated example, the tip 53e is positioned on the outer diameter side of the radial center M between the inner circumferential surface 17a of the inner ring 17 and the outer diameter end 22a of the crimping portion 22 (see Figure 5).

[0036] The tooth tips 53 of the hub-side face spline 52 are provided with a dense surface P formed by a mold (punch 60 described later) for forming the face spline 52, and a rough surface Q provided on the outer diameter side of the dense surface P that is not formed by the above-mentioned mold. In this embodiment, the second region 53b is the dense surface P, and the third region 53c and the fourth region 53d are the rough surfaces Q (see Figures 3 and 5).

[0037] As shown in the lower part of Figure 4, the bottom surface (tooth root 54) of the groove of the hub-side face spline 52 is gradually displaced outboard as it moves from the inner diameter end towards the outer diameter. In this embodiment, the tooth root 54 of the hub-side face spline 52 has a cylindrical surface shape that extends radially, and more specifically, it has a cylindrical surface shape that extends in a direction inclined outboard toward the outer diameter (see Figures 2-4).

[0038] In the radial region of the dense surface P (second region 53b) of the hub-side face spline 52, as shown in Figure 6, a cylindrical tooth tip 53 (second region 53b), a cylindrical tooth root 54, and a flat tooth surface 55 connecting the tooth tip 53 and the tooth root 54 are provided. In this radial region, the tooth tip 53 (second region 53b), the tooth root 54, and the tooth surface 55 are molded surfaces (dense surfaces) formed by a mold (punch 60) for forming the hub-side face spline 52.

[0039] The rough surface Q (third region 53c and fourth region 53d) has a surface roughness greater than that of the dense surface P. Visually, the dense surface P is a glossy surface, while the rough surface Q is not as glossy as the dense surface P. The radius of curvature of the rough surface Q in the circumferential cross-section is greater than that of the dense surface P (second region 53b), and in this embodiment, it is a substantially flat surface. Specifically, as shown in Figure 7, in the radial region of the rough surface Q of the hub-side face spline 52, a substantially flat tooth tip 53 (third region 53c in Figure 7), a cylindrical tooth root 54, and a flat tooth surface 55 connecting the tooth tip 53 and the tooth root 54 are provided. In this radial region, the tooth root 54 and the tooth surface 55 are molded surfaces (dense surfaces) formed by the above-mentioned die (punch 60), while the tooth tip 53 (third region 53c and fourth region 53d) is a surface (rough surface) that was not formed by the above-mentioned die.

[0040] As shown in Figure 5, the boundary N between the dense surface P and the rough surface Q is located on the inner diameter side of the apex 53e. That is, the apex 53e is formed on the rough surface Q of the tooth tip 53. The boundary N between the dense surface P and the rough surface Q is located on the outer diameter side of the radial center of the hub-side face spline 52, i.e., on the outer diameter side of the radial center between the outer diameter end 22a of the crimping portion 22 and the inner diameter end of the first region 53a, and in the illustrated example, it substantially coincides with the radial position of the inner circumferential surface 17a of the inner ring 17.

[0041] In this embodiment, not all of the entire rough surface Q of the tooth tip 53 of the hub-side face spline 52 is inclined outward in the outboard direction toward the outer diameter side. Among the rough surface Q, the inner diameter side portion (third region 53c) from the top 53e is inclined inward in the outboard direction toward the outer diameter side. Therefore, the axial height h (see FIG. 7) of the rough surface Q is ensured. In this case, the circumferential width W2 of the rough surface Q can be suppressed. For example, the circumferential width W2 at the radial center of the rough surface Q can be made 1.2 times or less the circumferential width W1 at the radial center of the dense surface P.

[0042] When the hub-side face spline 52 and the joint-side face spline 51 (see the chain line in FIGS. 6 and 7) are fitted together, the flat tooth surface 55 of the hub-side face spline 52 and the flat tooth surface 56 of the joint-side face spline 51 are in surface contact, and torque is transmitted through this surface contact portion. At this time, if the sag of the outer diameter portion of the hub-side face spline 52 is large, for example, if the rough surface Q of the tooth tip 53 drops to the position shown by the dotted line in FIG. 7, the contact area between the tooth surface 55 of the hub-side face spline 52 and the tooth surface 56 of the joint-side face spline 51 becomes small. Therefore, the surface pressure during torque transmission increases, leading to a decrease in strength and durability.

[0043] In this embodiment, among the rough surface Q of the tooth tip 53 of the hub-side face spline 52, the region (third region 53c) on the inner diameter side from the top 53e is inclined inward in the outboard direction toward the outer diameter side. That is, this region is inclined such that the axial height of the tooth tip 53 of the hub-side face spline 52 becomes higher as it goes toward the outer diameter side. As a result, the top 53e of the tooth tip 53 is arranged on the outer diameter side of the inner peripheral surface 17a of the inner ring 17, and as shown in FIG. 7, the axial height h in the rough surface Q of the tooth tip 53 can be ensured. As a result, the area of the tooth surface 55 is ensured, and the contact area between this tooth surface 55 and the tooth surface 56 of the joint-side face spline 51 is ensured. Therefore, the surface pressure during torque transmission decreases, and the strength and durability are enhanced.

[0044] Next, a method for manufacturing the above-described wheel bearing device 1, particularly a method for forming the caulking portion 22 and the hub-side face spline 52 on the hub ring 16 will be described.

[0045] First, an inner ring 17, an outer member 12, a double row of rolling elements 13, and a cage 14 are assembled on the outer periphery of the cylindrical portion 21 of the hub ring 16 to make it in the same state as in FIG. 11. At this time, the inboard side end portion of the cylindrical portion 21 of the hub ring 16 is not caulked, and a straight cylindrical portion 23 is provided (see the dotted line in FIG. 8).

[0046] After that, the inboard side end portion (cylindrical portion 23) of the cylindrical portion 21 of the hub ring 16 is caulked to the outer diameter side to form a caulked portion 22. In the present embodiment, the caulked portion 22 is formed in two steps, namely, a first caulking step and a second caulking step.

[0047] In the first caulking step, a punch is inserted into the inner periphery of the cylindrical portion 23 of the hub ring 16, and the cylindrical portion 23 is pressed outward in the radial direction from the inner periphery by this punch. As a result, the diameter of the cylindrical portion 23 is expanded to form a substantially tapered intermediate caulked portion 25 (see the solid line in FIG. 8).

[0048] In the second caulking step, the intermediate caulked portion 25 is further caulked to the outer diameter side to form a caulked portion 22 (see the chain line in FIG. 8). Specifically, the intermediate caulked portion 25 is pressed from above (inboard side) by the punch 60 shown in FIG. 9. On the lower surface of the punch 60, a tooth profile 61 for forming a hub side face spline 52 is provided. The tooth profile 61 has a form in which a plurality of ridges extending in the radial direction and a plurality of grooves extending in the radial direction are alternately arranged in the circumferential direction. The tooth tips 62 and the tooth bottoms 63 of the tooth profile 61 in the illustrated example are both in the form of a cylindrical surface and extend in a direction intersecting the axis K of the punch 60. The tooth tips 62 and the tooth bottoms 63 of the tooth profile 61 are separated from each other as they go to the outer diameter side. In the illustrated example, the tooth tip 62 extends in a direction orthogonal to the axis K, and the tooth bottom 63 extends in a direction inclined upward (the side away from the tooth tip 62) toward the outer diameter side. A flat tooth surface is provided between the tooth tip 62 and the tooth bottom 63, which is smoothly continuous with them.

[0049] With the axis K of the punch 60 tilted at an angle γ with respect to the axis L of the hub wheel 16, the tooth profile 61 of the punch 60 is pressed against the intermediate crimping portion 25 of the hub wheel 16 from above. At this time, the tooth tip 62 (the tooth tip 62 on the left in Figure 9) of the tooth profile 61 that contacts the intermediate crimping portion 25 is tilted outboard (downward in the figure) as it goes towards the outer diameter, and the tooth root 63 (the tooth root 63 on the left in Figure 7) of this portion is tilted inboard (upward in the figure) as it goes towards the outer diameter.

[0050] In this way, while pressing the tooth profile 61 of the punch 60 against the intermediate crimping portion 25, the axis K of the punch 60 is oscillated conically around the axis L of the hub wheel 16. As a result, the intermediate crimping portion 25 is further crimped outwards to form a crimping portion 22, and a hub-side face spline 52 is formed on the inboard end face (upper surface in Figure 9) of the crimping portion 22.

[0051] At this time, the tooth tips 62 of the tooth profile 61 of the punch 60 are pressed against the inboard end face of the crimping portion 22, and the entire radial area of ​​the tooth root 54 of the hub-side face spline 52 is formed. As a result, the tooth root 54 of the hub-side face spline 52 is a formed surface (dense surface P) that is formed entirely by the tooth tips 62 of the tooth profile 61 of the punch 60, and is formed in a cylindrical shape with the same shape as the tooth tips 62 of the tooth profile 61.

[0052] Furthermore, the material of the crimping portion 22 enters into the grooves of the tooth profile 61 of the punch 60, forming the protrusions of the hub-side face spline 52, and the tooth tip 53 is formed on the inboard end face of these protrusions. At this time, the inner diameter portion of the hub-side face spline 52 is filled up to the tooth root 63 of the tooth profile 61 of the punch 60, and a second region 53b formed by the tooth root 63 of the tooth profile 61 is formed in this portion. The second region is a molded surface (dense surface P) formed by the tooth root 63 of the tooth profile 61, and is formed in the shape of a cylindrical surface with the same shape as the tooth root 63.

[0053] On the other hand, the outer diameter portion of the hub-side face spline 52 does not extend to the tooth root 63 of the tooth profile 61 of the punch 60. Therefore, a third region 53c and a fourth region 53d are formed on the outer diameter portion of the tooth tip 53 of the hub-side face spline 52, which are not formed by the tooth root 63 of the tooth profile 61. The third region 53c and the fourth region 53d are rough surfaces Q with a rougher surface roughness than the second region 53b (dense surface P) which is formed by the tooth root 63 of the tooth profile 61. Because the cylindrical shape of the tooth root 63 is not transferred to the third region 53c and the fourth region 53d, they are formed with a cross-sectional shape that has a larger radius of curvature than the second region 53b, and in the illustrated example, is approximately flat.

[0054] In the hub-side face spline 52, at the circumferential position where it contacts the tooth profile 61 (left side of Figure 9), the rough surface Q (third region 53c and fourth region 53d) of the tooth tip 53 of the hub-side face spline 52 moves away from the tooth root 63 of the tooth profile 61 towards the outboard side (lower side of Figure 9) as it moves toward the outer diameter. At this time, by setting the molding conditions so that the inner diameter portion (third region 53c) of the rough surface Q fills as far as possible near the tooth root 63, the inner diameter portion (third region 53c) of the rough surface Q is inclined toward the inboard side (upper side of Figure 9) toward the outer diameter, thereby securing the axial height of this portion. As a result, the tip 53e of the tooth tip 53 of the hub-side face spline 52, which is positioned furthest inboard, is positioned outward from the inner circumferential surface 17a of the inner ring 17, and in particular, outward from the radial center M between the inner circumferential surface 17a of the inner ring 17 and the outer diameter end 22a of the crimping portion 22 (see Figure 5). The outer diameter portion of the rough surface Q (fourth region 53d) is inclined outward from the outer diameter towards the outboard side (lower side in Figure 9).

[0055] In this embodiment, as shown in Figure 8, the reduction in the axial dimension of the cylindrical portion 21 due to the first crimping process δ1 is made smaller than the reduction in the axial dimension of the cylindrical portion 21 due to the second crimping process δ2. The reduction in the axial dimension of the cylindrical portion 21 due to the first crimping process δ1 is the axial distance between the inboard side end of the cylindrical portion 23 before the first crimping process (upper end in Figure 8) and the inboard side end of the intermediate crimped portion 25 formed by the first crimping process. The reduction in the axial dimension of the cylindrical portion 21 due to the second crimping process δ2 is the axial distance between the inboard side end of the intermediate crimped portion 25 and the top 53e of the tooth tip 53 of the hub-side face spline 52 formed on the crimped portion 22. As described above, by reducing the amount of machining δ1 in the first crimping step, which does not form the hub-side face spline 52, and increasing the amount of machining δ2 in the second crimping step, which forms the hub-side face spline 52, the material of the crimped portion 22 can more easily enter the grooves of the tooth profile 61 of the punch 60 during the second crimping step. As a result, the axial height of the rough surface Q of the tooth tip 53 of the hub-side face spline 52 can be secured, and the top portion 53e can be positioned on the outer diameter side of the inner circumferential surface 17a of the inner ring 17.

[0056] The present invention is not limited to the above embodiments. For example, as shown in Figure 10, a projection 64 may be provided on the axis of the punch 60. The projection 64 is provided on the inner circumference of the tooth profile 61. The outer circumferential surface 65 of the projection 64 has a curved shape in which the angle with respect to the axis of the punch 60 increases as it moves toward the outer diameter. In this embodiment, the outer circumferential surface 65 of the projection 64 has the same cross-sectional shape as the first region 53a of the tooth tip 53 of the hub-side face spline 52. The outer circumferential surface 65 of the projection 64 is smoothly continuous with the tooth root 64 of the punch 60. By inserting this projection 64 into the inner circumference of the cylindrical portion 21 of the hub ring 16 and pressing the outer circumferential surface 65 of the projection 64 against the inner circumferential surface of the cylindrical portion 21, the cylindrical portion 21 can be restrained from the inner diameter side, thereby restricting plastic flow toward the inner diameter side of the cylindrical portion 21. In this state, by pressing the tooth profile 61 of the punch 60 against the inboard end face of the crimping portion 22 to form the hub-side face spline 52, the material of the cylindrical portion 21 can be actively allowed to flow outwards without being allowed to escape inwards. This makes it easier to fill the grooves of the tooth profile 61 near the outer diameter end of the hub-side face spline 52.

[0057] Furthermore, although the above embodiment shows a case in which the crimped portion 22 is formed in two stages, a first crimping step and a second crimping step, it is not limited to this. For example, the crimped portion 22 may be formed by applying a single crimping step to the cylindrical portion 23 (see Figure 8) provided at the inboard side end of the cylindrical portion 21 of the hub wheel 16, and the hub side face spline 52 may also be formed on the end face of the crimped portion 22.

[0058] 1 Wheel bearing device 2 Wheel bearing 3 Constant velocity universal joint 5, 6 Inner raceway surface 7 Inner member 10, 11 Outer raceway surface 12 Outer member 13 Rolling element 14 Cage 16 Hub ring 17 Inner ring 21 Cylinder section 22 Crimped section 23 Cylindrical section 31 Outer joint member 32 Inner joint member 33 Ball 37 Cage 50 Torque transmission section 51 Joint-side face spline 52 Hub-side face spline 53 Tooth tip 53a First area 53b Second area 53c Third area 53d Fourth area 53e Top 54 Tooth root 55 Tooth surface 56 Tooth surface 60 Punch 61 Tooth profile 62 Tooth tip 63 Tooth root P Fine surface Q Rough surface

Claims

1. A wheel bearing device comprising a wheel bearing and a constant velocity universal joint provided on the inboard side of the wheel bearing, wherein the wheel bearing comprises an outer member having double rows of outer raceway surfaces on its inner circumference, an inner member having double rows of inner raceway surfaces on its outer circumference, and a plurality of rolling elements disposed between the opposing inner raceway surfaces and the outer raceway surfaces, the inner member comprising a hub ring having a cylindrical portion and an inner ring fitted to the outer circumference of the cylindrical portion and having the inner raceway surface on the inboard side, a crimping portion provided at the inboard side end of the cylindrical portion of the hub ring that bends toward the outer diameter and contacts the inboard side end face of the inner ring, the constant velocity universal joint comprising an outer joint member fixed to the inner member, and face splines formed on the outer joint member and the crimping portion that are axially opposed and meshed in a torque-transmitting manner. A wheel bearing device in which the tip of the tooth of the face spline of the crimped portion, the tip that is positioned furthest inboard, is positioned on the outer diameter side of the inner circumferential surface of the inner ring.

2. The wheel bearing device according to claim 1, wherein the top portion is positioned on the outer diameter side of the radial center between the inner circumferential surface of the inner ring and the outer diameter end of the crimping portion.

3. The wheel bearing device according to claim 1, wherein the tooth tip of the face spline of the crimping portion has a dense surface and a rough surface provided on the outer diameter side of the dense surface and having a rougher surface roughness than the dense surface, and the top portion is provided on the rough surface.

4. The wheel bearing device according to claim 3, wherein the circumferential width of the tooth tips of the face splines of the crimping portion at the radial center of the rough surface is 1.2 times or less the circumferential width at the radial center of the dense surface.

5. A method for manufacturing a wheel bearing device comprising a wheel bearing and a constant velocity universal joint provided on the inboard side of the wheel bearing, wherein the wheel bearing comprises an outer member having double rows of outer raceway surfaces on its inner circumference, an inner member having double rows of inner raceway surfaces on its outer circumference, and a plurality of rolling elements disposed between the opposing inner raceway surfaces and the outer raceway surfaces, the inner member comprises a hub ring having a cylindrical portion and an inner ring fitted to the outer circumference of the cylindrical portion and having the inner raceway surface on the inboard side, a crimping portion is provided at the inboard side end of the cylindrical portion of the hub ring which is bent toward the outer diameter and contacts the inboard side end face of the inner ring, the constant velocity universal joint comprises an outer joint member fixed to the inner member, face splines are formed on the outer joint member and the crimping portion which face each other in the axial direction and mesh in a torque-transmitting manner, and when forming the crimping portion at the inboard side end of the cylindrical portion of the hub ring and forming the face splines on the end face of the crimping portion, A method for manufacturing a wheel bearing device, wherein the tip of the tooth of the face spline of the crimped portion that is positioned furthest inboard is positioned on the outer diameter side of the inner circumferential surface of the inner ring.

6. A method for manufacturing a wheel bearing device according to claim 5, comprising: a first crimping step of expanding the diameter of the inboard end of the cylindrical portion of the hub ring without forming the face spline; and a second crimping step of further expanding the diameter of the inboard end of the cylindrical portion to form the crimped portion, while forming the face spline on the end face of the crimped portion.

7. The method for manufacturing a wheel bearing device according to claim 6, wherein the amount of reduction in the axial dimension of the cylindrical portion due to the first crimping step is less than the amount of reduction in the axial dimension of the cylindrical portion due to the second crimping step.

8. The method for manufacturing a wheel bearing device according to claim 6, wherein in the second crimping step, the cylindrical portion of the hub ring is crimped while being restrained from the inner diameter side.

9. A method for manufacturing a wheel bearing device according to claim 8, wherein a projection is provided on the axis of the punch used in the second crimping step, the projection is inserted into the inner circumference of the cylindrical portion of the hub ring, and the cylindrical portion is restrained from the inner diameter side by pressing the outer surface of the projection against the inner surface of the cylindrical portion.

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