JP7537166B2 - Hub unit bearing and manufacturing method thereof, vehicle and manufacturing method thereof - Google Patents

Description

The present invention relates to a hub unit bearing for rotatably supporting the wheels of a vehicle such as an automobile relative to a suspension system, a method for manufacturing the same, and a vehicle and a method for manufacturing the same.

The wheels and braking rotors of an automobile are supported rotatably relative to the suspension by a hub unit bearing. In a hub unit bearing, the hub, which is the inner ring member, is usually constructed by combining multiple parts, including a first hub element and a second hub element fitted onto the first hub element. In order to reduce the number of parts that make up the hub, a structure in which the first hub element and the second hub element are joined and fixed by a crimped portion without using separate parts such as bolts and nuts is becoming widespread.

Figure 17 shows an example of a conventional structure of a hub unit bearing having a hub in which a first hub element and a second hub element are joined and fixed by a crimping portion, as described in JP Patent Publication No. 3-31001 (Patent Document 1). The hub unit bearing 100 has an outer ring 101, a hub 102, and a number of rolling elements 103.

Note that with respect to the hub unit bearing 100, the axially outer side is the outer side in the width direction of the vehicle when assembled to the vehicle, which is the left side in FIG. 17, and the axially inner side is the center side in the width direction of the vehicle when assembled to the vehicle, which is the right side in FIG. 17.

The outer ring 101 has double-row outer ring raceways 104a, 104b on its inner circumferential surface, and a stationary flange 105 that protrudes radially outward from the axially inner side. The stationary flange 105 has support holes 106 that penetrate in the axial direction at multiple locations in the circumferential direction. The outer ring 101 is supported and fixed to the suspension by support bolts that are screwed into the support holes 106 of the stationary flange 105, and does not rotate even when the wheel rotates.

The hub 102 is disposed coaxially with the outer ring 101 on the radially inner side of the outer ring 101, and has double-row inner ring raceways 107a, 107b on its outer circumferential surface. The hub 102 has a rotating flange 108 that protrudes radially outward at a portion located axially outward from the outer ring 101, and a cylindrical pilot portion 109 at the end on the axially outer side. The rotating flange 108 has mounting holes 110 that penetrate in the axial direction at multiple locations in the circumferential direction. The braking rotor and the wheel that constitutes the wheel are fixed to the rotating flange 108 by inserting the pilot portion 109 into the central hole provided in the center and inserting the hub bolt into the through hole provided in multiple locations in the circumferential direction of the radial middle portion, and screwing the hub bolt into the mounting hole.

In the illustrated example, the hub 102 is formed by connecting and fixing a first hub element 111 and a second hub element 112.

The first hub element 111 is cylindrically configured, has an axially outer inner ring raceway 107a of the double row inner ring raceways 107a, 107b on the outer peripheral surface of the axially inner part, and has a rotating flange 108 and a pilot portion 109 on the axially outer part. The second hub element 112 has a base 113 having an axially inner inner ring raceway 107b of the double row inner ring raceways 107a, 107b on the outer peripheral surface, a mating shaft portion 114 that extends axially outward from the radially inner part of the base 113 and has the first hub element 111 fitted thereon, and a crimping portion 115 that bends radially outward from the axially outer end of the mating shaft portion 114 and presses down the radially inner end of the axially outer side surface of the first hub element 111. That is, the first hub element 111 is fixedly connected to the second hub element 112 by being clamped from both axial sides between the axially outer side surface of the base 113 of the second hub element 112 and the axially inner side surface of the crimping portion 115.

The rolling elements 103 are arranged between the double row outer ring raceways 104a, 104b and the double row inner ring raceways 107a, 107b, with multiple rolling elements arranged in each row.

Japanese Patent Application Publication No. 3-31001

Meanwhile, a moment load based on road reaction force is applied to the above-mentioned hub unit bearing 100 mainly when the automobile is turning. Stress based on such moment loads tends to concentrate on the radially inner part of the axially inner side surface of the crimped portion 115. For this reason, if the hub unit bearing 100 is used continuously for a long period of time, a crack may develop starting from the radially inner part of the axially inner side surface of the crimped portion 115, and as this crack propagates, the crimped portion 115 may be damaged.

However, the progression of a crack originating from the radially inner part of the axially inner side surface of the crimped portion 115 is difficult to see even when the crimped portion 115 is viewed from the outside in the axial direction. In other words, with the conventional hub unit bearing 100, it is difficult to grasp the damage state of the crimped portion 115, and it is difficult to determine the timing of replacement depending on the damage state of the crimped portion 115. Therefore, in order to prevent damage to the crimped portion 115 from becoming a cause for replacement, it is necessary to design the crimped portion 115 to be excessively strong, but this results in an unnecessarily heavy weight and increases the manufacturing costs of the hub unit bearing 100.

In view of the above circumstances, the present invention aims to realize a hub unit bearing structure that makes it easy to grasp the damage condition of the crimped portion.

The hub unit bearing of the present invention comprises an outer ring having a double-row outer ring raceway on its inner surface, a hub having a double-row inner ring raceway on its outer surface, and rolling elements arranged between the double-row outer ring raceway and the double-row inner ring raceway, with multiple rolling elements arranged in each row.
The hub includes a first hub element and a second hub element.
The first hub element has an axially outer inner ring raceway of the double row inner ring raceways on its outer surface, a central hole at its radial center, a clamped surface on its axially outer side, and a boundary edge portion at the boundary between the central hole and the clamped surface.
The second hub element comprises a base having an axially inner inner ring raceway of the double row inner ring raceways on its outer surface, a mating shaft portion extending axially outward from the radially inner portion of the base and inserted into the central hole of the first hub element, and a crimping portion adjacent to the axially outer side of the mating shaft portion and pressing down on the pressed surface.
The crimping portion has a slit that connects the boundary edge portion with the outside.

In one embodiment of the hub unit bearing of the present invention, the slits are provided at multiple locations in the circumferential direction of the crimped portion.

In one embodiment of the hub unit bearing of the present invention, the slits are provided at multiple locations that are equally spaced circumferentially around the crimped portion.

In one embodiment of the hub unit bearing of the present invention, the slits open on the axially outer side and on both radial sides of the crimped portion.

In one embodiment of the hub unit bearing of the present invention, the slit opens to the axially outer side and the radially outer side of the crimped portion, and the portion of the crimped portion located radially inward of the slit is connected around the entire circumference.

In one embodiment of the hub unit bearing of the present invention, the clamped surface is inclined in a direction toward the axially outward direction as it moves radially outward, and the axially outer side surface of the crimped portion is formed by a flat surface that is perpendicular to the central axis of the second hub element.

In one aspect of the hub unit bearing of the present invention, the crimping portion has a radially intermediate portion connected to the axially outer end of the mating shaft portion, a pressing portion that protrudes radially outward from the radially intermediate portion and presses down on the pressed surface, and an inward flange portion that protrudes radially inward from the radially intermediate portion.

In one aspect of the hub unit bearing of the present invention, a rotation prevention engagement portion is provided between the first hub element and the second hub element to prevent relative rotation between the first hub element and the second hub element.

In one aspect of the hub unit bearing of the present invention, the anti-rotation engagement portion is configured by meshing a first face spline provided on the axially inner end face of the first hub element with a second face spline provided on the axially outer end face of the base of the second hub element.

In one aspect of the hub unit bearing of the present invention, the hub unit bearing further comprises a first flat surface portion present on a portion of the axially inner end face of the first hub element that is located radially to one side of the first face spline (radially inner or radially outer) and that is constituted by a circular annular plane centered on the central axis of the first hub element, and a second flat surface portion present on a portion of the axially outer end face of the base of the second hub element that is located radially to one side of the second face spline and that is constituted by a circular annular plane centered on the central axis of the second hub element.
The first flat portion and the second flat portion are in contact with each other, and the axial side surfaces of the first face spline and the second face spline that face each other do not in contact with each other.

In one aspect of the hub unit bearing of the present invention, the anti-rotation engagement portion is configured by engaging each of the slits with an engagement protrusion provided on the first hub element.

The vehicle of the present invention includes a hub unit bearing.
In particular, in the vehicle of the present invention, the hub unit bearing is the hub unit bearing of the present invention.

The method for manufacturing a hub unit bearing of the present invention is intended to manufacture the hub unit bearing of the present invention.
The manufacturing method of the hub unit bearing of the present invention includes the steps of:
obtaining the second hub element before forming the crimping portion, the second hub element including a cylindrical portion extending axially outward from an axially outer end of the fitting shaft portion and having an axial slit extending axially at at least one location in a circumferential direction; and inserting the fitting shaft portion into the central hole of the first hub element.
a step of forming the crimped portion by pressing the cylindrical portion in the axial direction while rotating a stamping die, the stamping die being supported for free rotation about a rotation axis inclined with respect to the central axis of the second hub element and having a convex curved processed surface portion with a linear generatrix inclined with respect to the rotation axis, against an axially outer end face of the cylindrical portion, and using the crimped portion to press against the held surface, thereby joining and fixing the first hub element and the second hub element together;
Equipped with.

In one aspect of the manufacturing method of the hub unit bearing of the present invention, in the step of joining and fixing the first hub element and the second hub element, within an imaginary plane including the central axis of the second hub element and the rotation axis, the abutment portion between the cylindrical portion and the machined surface portion exists on a straight line perpendicular to the central axis of the second hub element.

In one aspect of the manufacturing method of the hub unit bearing of the present invention, in the process of connecting and fixing the first hub element and the second hub element, the apex of an imaginary conical surface including the machined surface portion is located at the intersection of the central axis of the second hub element and the rotation axis.

In one aspect of the manufacturing method of the hub unit bearing of the present invention, a test is conducted to examine the relationship between the inclination angle of the rotation axis relative to the central axis of the second hub element and the shape of the axially inner side surface of the crimped portion, and based on the results of the test, the inclination angle that allows the axially inner side surface of the crimped portion to be shaped to conform to the clamped surface is determined, and the determined inclination angle is used to perform a process of joining and fixing the first hub element and the second hub element.

The vehicle manufacturing method of the present invention is directed to manufacturing a vehicle equipped with a hub unit bearing.
The vehicle manufacturing method of the present invention manufactures the hub unit bearing by the hub unit bearing manufacturing method of the present invention.

The hub unit bearing of the present invention makes it easy to determine the damage condition of the crimped portion.

FIG. 1 is a cross-sectional view showing a hub unit bearing according to a first embodiment of the present invention in a state where it is installed on a vehicle. FIG. 2 is a perspective view of a hub according to a first embodiment as viewed from the outside in the axial direction. Figures 3(A) and 3(B) are views of the radially inner portion of the hub of a first example of an embodiment as viewed from the axially outer side. Specifically, Figure 3(A) is a view showing a state in which the crimped portion is not damaged, and Figure 3(B) is a view showing a state in which the crimped portion is damaged. FIG. 4 is a half cutaway perspective view of a first hub element of the first example embodiment. FIG. 5 is a cross-sectional view showing a state at the start of processing for forming the crimped portion according to the first embodiment. FIG. 6 is a cross-sectional view showing the state at the end of processing for forming the crimped portion according to the first embodiment. FIG. 7 is a half-sectional perspective view showing the same state as FIG. 5, with only the hub and the die taken out. FIG. 8 is a half-sectional perspective view showing the same state as in FIG. 6, with only the hub and the die taken out. FIG. 9 is a cross-sectional view showing a test assembly set in a rocking device according to the first embodiment. 10(A) to 10(D), the upper half of which is a partial plan view showing the contact portion S of the mold with the test piece, and the lower half of which is a partial cross-sectional view showing the shape of the plastically processed region V and the crimped portion of the test piece. FIG. 11 is a cross-sectional view of a hub that constitutes a hub unit bearing according to a second example of the embodiment. FIG. 12 is a diagram corresponding to FIG. 4 and related to the second embodiment. FIG. 13 is a cross-sectional view of a hub unit bearing according to a third example of the embodiment. FIG. 14(A) is a cross-sectional view showing the state at the start of processing to form a crimped portion for a third example of an embodiment, and FIG. 14(B) is a cross-sectional view showing the state at the end of processing to form the crimped portion. FIG. 15(A) is a cross-sectional view of a hub that constitutes a hub unit bearing of a fourth example of an embodiment, and FIG. 15(B) is a cross-sectional view of a hub that constitutes a hub unit bearing of a fifth example of an embodiment. 16A is a cross-sectional view showing the state at the start of processing to form a crimped portion in a sixth example of the embodiment, and FIG. 16B is a cross-sectional view showing the state at the end of processing to form the crimped portion. FIG. 17 is a cross-sectional view showing an example of a conventional structure of a hub unit bearing.

[First Example of the Embodiment]
A first embodiment of the present invention will be described with reference to FIGS. 1 to 10. FIG.

(Structure of hub unit bearing 1)
1 shows a hub unit bearing 1 of this embodiment. The hub unit bearing 1 is for use as a driven wheel of a large vehicle such as a truck, bus, or large passenger car, and includes an outer ring 2, a hub 3, and a plurality of rolling elements 4a, 4b.

With regard to the hub unit bearing 1, the axially outer side is the left side in FIG. 1, which is the outer side in the width direction of the vehicle when assembled to the vehicle, and the axially inner side is the right side in FIG. 1, which is the center side in the width direction of the vehicle when assembled to the vehicle.

The outer ring 2 is made of hard metal such as medium carbon steel and includes double-row outer ring raceways 5a, 5b and a stationary flange 6. The double-row outer ring raceways 5a, 5b are formed on the inner peripheral surface of the axially middle portion of the outer ring 2 and are configured as conical concave surfaces that are inclined in a direction such that the diameter increases as they move away from each other in the axial direction. The stationary flange 6 protrudes radially outward from the axially middle portion of the outer ring 2 and has support holes 7 configured as screw holes at multiple locations in the circumferential direction.

The outer ring 2 is supported and fixed to the knuckle 8, which constitutes the vehicle suspension system, by threading a bolt 10 through a through hole 9 in the knuckle 8 and screwing it into the support hole 7 in the stationary flange 6 from the inside in the axial direction.

The hub 3 is arranged coaxially with the outer ring 2 on the radial inside of the outer ring 2, and includes double row inner ring raceways 11a, 11b, a rotating flange 12, and a pilot portion 13. The double row inner ring raceways 11a, 11b are formed on the outer peripheral surface of the hub 3 in a portion facing the double row outer ring raceways 5a, 5b, and are configured as conical convex surfaces inclined in a direction in which the diameter increases as they move away from each other in the axial direction. The rotating flange 12 protrudes radially outward from the axially outer portion of the hub 3 located axially outward from the outer ring 2, and has mounting holes 14 (shown only in Figures 1 and 4, not shown in other figures) at multiple locations in the circumferential direction. The pilot portion 13 is configured in a cylindrical shape extending axially outward from a portion of the axially outer portion of the hub 3 adjacent to the radially inner side of the rotating flange 12.

In the illustrated example, in order to connect and fix a braking rotor 15 such as a disk or drum to the rotating flange 12, the braking rotor 15 is fitted onto the axially inner side of the pilot portion 13, the serration portion provided on the base end of the stud 16 is pressed into the mounting hole 14, and the middle portion of the stud 16 is pressed into the through hole 17 of the braking rotor 15. Furthermore, in order to fix a wheel 18 constituting a wheel to the rotating flange 12, the wheel 18 is fitted onto the axially outer side of the pilot portion 13, and the male thread portion provided on the tip of the stud 16 is inserted into the through hole 19 of the wheel 18, and a nut 20 is screwed onto the male thread portion and tightened.

The rolling elements 4a, 4b are each made of hard metal such as bearing steel or ceramics, and are arranged in multiples for each row between the double row outer ring raceways 5a, 5b and the double row inner ring raceways 11a, 11b. The rolling elements 4a, 4b are held in each row by cages 21a, 21b so that they can roll freely. In this example, the rolling elements 4a, 4b are each tapered rollers.

In particular, in the hub unit bearing 1 of this example, the hub 3 is formed by joining and fixing a first hub element 22 and a second hub element 23, each of which is made of a hard metal such as medium carbon steel.

The first hub element 22 is configured in a cylindrical shape, has the axially outer inner ring raceway 11a of the double row inner ring raceways 11a, 11b on the outer peripheral surface of the axially inner portion, and has a rotating flange 12 and a pilot portion 13 on the axially outer portion. The first hub element 22 also has a central hole 24 that axially penetrates the radial center of the axially intermediate portion and the inner portion. The inner peripheral surface of the central hole 24 is configured as a cylindrical surface whose inner diameter does not change in the axial direction.

The first hub element 22 has a restrained surface 25, which is held down by a restraining portion 31 (described later), on the periphery of the axially outer opening of the central hole 24 on the axially outer side surface. That is, the first hub element 22 has a boundary edge 56 at the boundary between the central hole 24 and the restrained surface 25. In other words, the boundary edge 56 exists at the connection between the axially outer end of the central hole 24 and the radially inner end of the restrained surface 25. In the illustrated example, the boundary edge 56 is a corner, but it can also be a convex curved surface. In this example, the radially inner part (the part located radially inner than the pilot portion 13) of the axially outer surface of the first hub element 22, including the restrained surface 25, is configured as a conical concave surface that is inclined in the axially outer direction as it moves radially outward. In this example, the restrained surface 25 is arranged at a position that overlaps the rotating flange 12 in the radial direction. In addition, when implementing the present invention, the clamped surface can be configured, for example, as a concave curved surface whose cross-sectional shape (generatrix shape) is a curved shape such as a circular arc, which is inclined in the axially outward direction as it approaches the radially outward direction. Furthermore, the first hub element 22 has a first face spline 26, which is a circumferentially uneven portion, on the axially inner end face.

The second hub element 23 is provided with a cylindrical base 27 having the axially inner inner raceway 11b of the double row inner raceways 11a, 11b on its outer circumferential surface, a cylindrical mating shaft 28 that extends from the radially inner side of the base 27 toward the axially outer side and is inserted into the central hole 24 of the first hub element 22 without any radial play (the first hub element 22 is fitted with a clearance fit that does not cause any radial play), and a crimping portion 29 that is adjacent to the axially outer side of the mating shaft 28 and presses against the pressed surface 25.

The base 27 has a second face spline 30, which is a circumferentially uneven portion, on its axially outer end face. The second face spline 30 meshes with the first face spline 26 without any circumferential backlash, forming a rotation prevention engagement portion that prevents relative rotation between the first hub element 22 and the second hub element 23.

The crimping portion 29 is configured in an annular shape as a whole, and has a radial intermediate portion 57 connected to the axially outer end of the fitting shaft portion 28, a holding portion 31 that protrudes radially outward from the radial intermediate portion 57 and holds down the held surface 25, and an inward flange portion 32 that protrudes radially inward from the radial intermediate portion 57. In other words, the radial intermediate portion 57 of the crimping portion 29 is a portion that is connected to the axially outer end of the fitting shaft portion 28, and is sandwiched from both radial sides by the holding portion 31 and the inward flange portion 32. In addition, the holding portion 31, which is the radially outer portion of the crimping portion 29, protrudes radially outward from the outer peripheral surface of the fitting shaft portion 28. In addition, the inward flange portion 32, which is the radially inner portion of the crimping portion 29, protrudes radially inward from the inner peripheral surface of the fitting shaft portion 28.

The crimping portion 29 has a substantially trapezoidal cross-sectional shape when cut on a virtual plane including the central axis of the second hub element 23. The holding portion 31, which is the radially outer portion of the crimping portion 29, has a substantially triangular cross-sectional shape in which the axial width dimension decreases toward the radially outer side when cut on a virtual plane including the central axis of the second hub element 23. The inward flange portion 32, which is the radially inner portion of the crimping portion 29, has a substantially triangular cross-sectional shape in which the axial width dimension decreases toward the radially inner side when cut on a virtual plane including the central axis of the second hub element 23. The radial intermediate portion 57 of the crimping portion 29 has a substantially rectangular cross-sectional shape. In addition, the axially outer side surface 33 of the crimping portion 29, including the axially outer side surfaces of the radial intermediate portion 57, the holding portion 31, and the inward flange portion 32, is configured by a flat surface perpendicular to the central axis of the second hub element 23.

The crimped portion 29 also has slits 34 that connect the boundary edge portion 56 to the outside. In this example, as is particularly clear from Figures 2 and 3, the slits 34 are provided at multiple locations in the circumferential direction of the crimped portion 29, and each slit extends in the radial direction. In particular, in this example, the slits 34 are provided at four locations that are equally spaced in the circumferential direction of the crimped portion 29. Each of the slits 34 is provided across the entire axial width and the entire radial width of the crimped portion 29, and opens to the axial outside and both radial sides of the crimped portion 29. As shown in Figure 3 (A), the width dimension of the slits 34 in the circumferential direction is approximately constant in the radial direction. However, the width dimension of the slits 34 in the circumferential direction can also be made larger toward the radial outside.

That is, in the structure of this example, the crimping portion 29 is divided into four in the circumferential direction by the slits 34. In other words, the crimping portion 29 has four divided crimping portions 51, each of which is disposed between adjacent slits 34 in the circumferential direction (disposed at a distance in the circumferential direction). Each of the divided crimping portions 51 has a fan shape when viewed from the outside in the axial direction, as shown in FIG. 3(A).

In addition, each of the split crimping portions 51 has a split holding portion 45 that constitutes the holding portion 31 on the radially outer side, and a split inward flange portion 46 that constitutes the inward flange portion 32 on the radially inner side. Each of the split holding portion 45 and the split inward flange portion 46 also has a fan shape when viewed from the outside in the axial direction.

The clamping portion 29 is configured as described above by the clamping portion 31 (each of the split clamping portions 45) which clamps the clamped surface 25 of the first hub element 22. The clamping surface 35, which is the axial inner surface of the clamping portion 31 (each of the split clamping portions 45) that contacts the clamped surface 25, has a shape that conforms to the clamped surface 25.

In other words, the hub 3 of this example is constructed by fitting the first hub element 22 onto the mating shaft portion 28 of the second hub element 23, and by engaging the first face spline 26 of the first hub element 22 with the second face spline 30 of the second hub element 23, and then clamping the first hub element 22 in the axial direction between the axially outer end face of the base 27 of the second hub element 23 (the tip face (the surface facing axially outward) of the convex portion constituting the second face spline 30 and/or the bottom face (the surface facing axially outward) of the concave portion) and the clamping surface 35, which is the axially inner surface of the clamping portion 31, to thereby bond and fix the first hub element 22 and the second hub element 23. In addition, with the first hub element 22 and the second hub element 23 bonded and fixed in this manner, an appropriate preload is applied to the rolling elements 4a and 4b.

When implementing the present invention, the number of slits 34 and their width in the circumferential direction can be determined appropriately within the range in which the force with which the holding portion 31 holds down the held surface 25 and the strength of the holding portion 31 can be ensured.

(Manufacturing method of hub unit bearing 1)
The hub unit bearing 1 of this example is manufactured as follows. First, a metal material is subjected to forging and cutting, and then finishing such as polishing to manufacture the second hub element 23z before the crimped portion 29 is formed, as shown in Figs. 5 and 7. The second hub element 23z has a cylindrical portion 36 that extends axially outward from the axially outer end of the fitting shaft portion 28. The cylindrical portion 36 has axial slits 37 that extend in the axial direction at multiple locations in the circumferential direction (four locations that are equally spaced in the circumferential direction in this example). The axial slits 37 open to the axially outer end face, inner peripheral surface, and outer peripheral surface of the cylindrical portion 36. The circumferential width dimension of the axial slits 37 is constant in the axial direction.

In this example, the outer shape of the second hub element 23z is formed by forging, and then cutting is performed at multiple circumferential locations on the cylindrical portion 36 to form the axial slits 37. However, the axial slits 37 can also be formed at the same time that the outer shape of the second hub element 23z is formed by forging. In other words, by providing a protrusion extending in the axial direction in a portion of the die used when forging the second hub element 23z that corresponds to the axial slits 37, the axial slits 37 can be formed at the same time that the outer shape of the second hub element 23z is formed by forging.

Next, the rolling elements 4a of the axially outer row are arranged around the inner ring raceway 11a of the first hub element 22 on the axially outer side, in a state held by the axially outer retainer 21a, and the outer ring 2 is arranged around the first hub element 22. Next, the rolling elements 4b of the axially inner row are arranged around the inner ring raceway 11b of the second hub element 23z on the axially inner side, in a state held by the axially inner retainer 21b. Then, the mating shaft portion 28 of the second hub element 23 is inserted into the center hole 24 of the first hub element 22, and the second face spline 30 and the first face spline 26 are meshed. At this time, the first hub element 22 is externally fitted onto the mating shaft portion 28 of the second hub element 23z with a clearance fit that does not cause any radial rattle. In this way, the hub unit bearing 1z before the crimping portion 29 is formed is assembled, as shown in FIG. 5. The process for assembling the hub unit bearing 1z can be modified as needed as long as no contradictions arise.

Next, the cylindrical portion 36 is machined to form the crimped portion 29. To do this, specifically, as shown in FIG. 5, the hub unit bearing 1z is set in the rocking crimping device 38 with the axially outer portion of the hub unit bearing 1z facing upward.

The rocking device 38 includes a holder (not shown) that supports the second hub element 23z, and a tool called a die 39.

The pressing die 39 has a rotation axis L inclined at an angle α (0<α<90°) with respect to the central axis (reference axis) C of the second hub element 23z. The pressing die 39 can be driven to rotate (revolve) around the central axis C of the second hub element 23z by a drive source such as an electric motor with respect to a ram (not shown), and is supported to rotate (spin) freely around the rotation axis L.

The die 39 has a machining surface 40 on the lower side, which is a convex curved surface (a conical convex surface centered on the rotation axis L) with a linear generatrix inclined with respect to the rotation axis L. In this example, the inclination angle β of the generatrix of the machining surface 40 with respect to the rotation axis L is (90°-α). That is, in this example, in an imaginary plane including the central axis C of the second hub element 23z and the rotation axis L, the part of the machining surface 40 located at the lower end (part X in Figures 5 and 6) exists on a straight line perpendicular to the central axis C of the second hub element 23z (23). Also, in this example, the apex of the imaginary cone including the machining surface 40 exists at the intersection P of the central axis C of the second hub element 23z and the rotation axis L.

The angle α of the rocking device 38 is adjusted in advance using the method described below so that the clamping surface 35 of the clamping portion 31 after completion will have a shape that matches the clamped surface 25.

When forming the crimped portion 29 using the above-mentioned oscillating crimping device 38, as shown in Figs. 5 and 6, the ram is lowered to move the stamping die 39 downward, or the holder is raised to move the hub unit bearing 1 upward, so that a portion (X portion) located at the lower end of a circumferential portion of the processing surface portion 40 of the stamping die 39 is pressed against the axially outer end face of the cylindrical portion 36 of the second hub element 23, while the driving source rotates the stamping die 39 around the central axis C of the second hub element 23 (accompanying this, the stamping die 39 is rotated around the rotation axis L based on the frictional force acting on the contact portion between the processing surface portion 40 and the cylindrical portion 36), thereby processing the cylindrical portion 36 into the crimped portion 29.

That is, in this example, in a virtual plane including the central axis C and the rotation axis L of the second hub element 23, the abutment portion between the machining surface portion 40 and the cylindrical portion 36 is located on a straight line perpendicular to the central axis C of the second hub element 23, so that a machining force directed downward in the vertical direction is applied from the machining surface portion 40 to a part of the circumferential direction of the cylindrical portion 36. In addition, the position where this machining force is applied is continuously changed in the circumferential direction of the cylindrical portion 36 in accordance with the rotation of the stamping die 39 about the central axis C of the second hub element 23 (and the rotation of the stamping die 39 about the rotation axis L), thereby crushing the cylindrical portion 36 in the axial direction. In this way, the cylindrical portion 36 is machined into the crimped portion 29. That is, the holding portion 31 and the inward flange portion 32 are formed, and the axial slits 37 extending in the axial direction are machined into slits 34 extending in the radial direction (in other words, the slits 34 are formed at multiple locations that are in phase with the axial slits 37 in the circumferential direction). Then, the first hub element 22 and the second hub element 23 are joined and fixed together by pressing the pressed surface 25 with the pressing portion 31 that has been formed.

In this example, within an imaginary plane including the central axis C and the rotation axis L of the second hub element 23, the abutment portion between the machined surface portion 40 and the cylindrical portion 36 is located on a straight line perpendicular to the central axis C of the second hub element 23, so that the axially outer side surface 33 of the crimping portion 29, including the axially outer side surfaces of the retaining portion 31 and the inward flange portion 32, becomes a flat surface perpendicular to the central axis C of the second hub element 23.

(How to adjust the angle α)
Next, using Figures 9 and 10, we will explain how to adjust the angle α (and β = 90° - α) of the oscillating restraining device 38 so that the shape of the clamping surface 35 of the clamping portion 31 can be made to conform to the clamped surface 25.

First, multiple press dies 39 with different angles α (and β) are prepared. Then, for each prepared press die 39, a test is performed to form a crimped portion 29z (see Figures 10(A) to 10(D)) with a retainer 31z using a rocking and crimping device 38 including the press die 39. Such a test can be performed, for example, using a test assembly 41 as shown in Figure 9.

The test assembly 41 is set below the press die 39 with respect to the rocking and pressing device 38, and includes a support base 42, a support tube member 43, and a test piece 44. The support base 42 is prevented from moving radially around the reference axis C, which is the central axis of rotation (revolution) of the press die 39. The support tube member 43 is arranged coaxially with the reference axis C and is supported and fixed on the upper surface of the support base 42. The test piece 44 is cylindrical and is supported by the support tube member 43 without any radial play, so that it is arranged coaxially with the reference axis C, its lower end surface is supported by the upper surface of the support base 42, and its upper end protrudes upward from the inner diameter side of the support tube member 43. The material of the test piece 44 and the shape and size of the upper end of the test piece 44 are the same as the cylindrical portion 36 of the hub unit bearing 1 before the crimping portion 29 is formed. That is, the test piece 44 has axial slits 37 (not shown) at multiple locations around the circumference of the upper end.

For each of the multiple press dies 39 with different angles α (and β), a test is conducted to form a crimped portion 29z at the upper end of the test piece 44 constituting the test assembly 41 using a vibration crimping device 38 including the press die 39, and the test results shown in Figures 10(A) to 10(D) are obtained. As shown in the test results, the shape of the holding portion 31z of the crimped portion 29z differs depending on the angle α (and β). This is because the area (circumferential width) of the contact portion (diagonal grid area S) of the machined surface portion 40 with the test piece 44 changes depending on the angle α (and β), and the volume (axial depth) of the plastic deformation area (diagonal grid area V) of the test piece 44 changes accordingly. Specifically, the larger the angle α, the smaller the area (circumferential width) of the contact portion S, and the smaller the volume (axial depth) of the plastic deformation area V. In particular, the clamping surfaces 35z of the clamping portions 31z are all inclined surfaces (convex surfaces with a roughly arc-shaped generatrix or tapered surfaces with a roughly straight generatrix) that are inclined in the axial direction (upper side in Figures 10(A) to 10(D)) as they move radially outward, but the specific shape differs depending on the angle α (and β).

Therefore, based on the test results as described above, the angle α (and β) at which the clamping surface 35z of the clamping portion 31z is shaped to conform to the clamped surface 25 of the first hub element 22 is determined. In other words, from the test results as described above, the angle α (and β) at which the clamping surface 35z of the clamping portion 31z is shaped to conform to the clamped surface 25 of the first hub element 22 is selected. For example, in the illustrated example, the clamping surface 35z of the clamping portion 31z shown in FIG. 10(C) is shaped to conform to the clamped surface 25 of the first hub element 22 (see FIGS. 5 and 6), so the angle α can be selected to be 30°. In this example, the angle α selected in this manner is used to form the crimped portion 29 when manufacturing the hub unit bearing 1.

In this example, the machining surface portion 40 of the pressing die 39 is cone-shaped, and the contact portion between the machining surface portion 40 and the cylindrical portion 36 is located on a straight line perpendicular to the central axis C of the second hub element 23 in a virtual plane including the central axis C and the rotation axis L of the second hub element 23. Therefore, in the process of crushing the cylindrical portion 36 in the axial direction by the machining surface portion 40, a part of the crushed material tends to flow radially inward along the machining surface portion 40. This tendency becomes greater as the angle α becomes larger (in other words, as the shape of the contact portion S becomes closer to a rectangle, or further, as the difference in the amount of deformation between the outer diameter side and the inner diameter side becomes smaller). Then, as shown in Figures 10(A) to 10(D), when the angle α becomes a predetermined value or more (15° or more in the illustrated example), an inward flange portion 32 (32z) that protrudes radially inward is formed on the radially inner side of the completed crimped portion 29 (29z). FIG. 1 shows an example in which such an inward flange 32 is formed. The inward flange 32 (split inward flange 46) can function as a reinforcing rib to maintain the shape of the crimped portion 29 (29z) (split crimped portion 51). However, the inward flange 32 may be removed by cutting or other processing, if necessary.

The hub unit bearing 1 of this example, as described above, makes it easy to determine the damage condition of the crimped portion 29.

That is, in the hub unit bearing 1 of this example, the crimped portion 29 has a slit 34 that connects the boundary edge portion 56 to the outside. The crimped portion 29 is divided into a plurality of divided crimped portions 51 arranged at intervals in the circumferential direction by the slits 34 provided at a plurality of locations in the circumferential direction. The holding portion 31 constituting the radially outer portion of the crimped portion 29 is also divided into a plurality of divided holding portions 45 arranged at intervals in the circumferential direction. For this reason, when a crack occurs starting from the radially inner portion (the portion facing the boundary edge portion 56) of the holding surface 35 of the holding portion 31, the crack may be confirmed by visually inspecting the circumferential side of the divided holding portion 45 through the slit 34. By performing such an inspection, the damage condition of the crimped portion 29 can be easily grasped.

In addition, in the structure of this example, if no cracks are generated starting from the radial inner part of the clamping surface 35 of the clamping portion 31, or if the cracks are generated but do not progress significantly, each of the split clamping portions 51 (split clamping portions 45) has a defect-free fan shape when viewed from the axial outside, as shown in FIG. 3(A). In contrast, if a crack is generated starting from the radial inner part of the clamping surface 35 of the clamping portion 31 and progresses significantly, a missing portion 47 is generated in a part of one of the split clamping portions 45, or a part of the crack appears on the axial outer surface of one of the split clamping portions 45, as shown in FIG. 3(B). For this reason, such missing portions 47 and cracks can be visually confirmed from the axial outside of the clamping portion 31. By performing such confirmation, the damage status of the clamping portion 29 can be easily grasped.

In addition, in the structure of this example, the slits 34 of the crimping portion 29 are arranged at equal intervals in the circumferential direction, so the crimping portion 29 (retaining portion 31) without the missing portion 47 has a symmetrical shape as shown in FIG. 3(A). In contrast, when a missing portion 47 occurs, the symmetry of this shape is lost, which has the advantage that the presence of the missing portion 47 can be easily recognized by visual inspection.

Visual inspection of cracks (especially small cracks) can be facilitated by color check testing using dye penetrants, which are well known in the art.

In addition, in the structure of this example, the crimped portion 29 is located at the axially outer end of the hub unit bearing 1. As a result, during vehicle maintenance, the hub unit bearing 1 does not need to be removed from the vehicle, i.e., the hub unit bearing 1 is still attached to the vehicle, and the damage condition of the crimped portion 29 (missing portion 47 or cracks) can be visually confirmed from the axially outer side of the crimped portion 29. This effect is particularly noticeable in the maintenance of large vehicles, where it is troublesome to remove the hub unit bearing 1 from the vehicle, and as a result, the ease of maintenance of the hub unit bearing 1 for large vehicles can be improved.

In addition, in the structure of this example, since the slits 34 are present at multiple points in the circumferential direction of the retaining portion 31, if a crack occurs at one point in the circumferential direction of the crimped portion 29, the slits 34 can stop the crack from progressing in the circumferential direction. Therefore, it is possible to prevent a crack that occurs at one point in the circumferential direction from progressing around the entire circumference, as is the case with conventional crimped portions, i.e., crimped portions that do not have slits and are continuous around the entire circumference.

In addition, in the structure of this example, the slits 34 of the crimping portion 29 (retaining portion 31) are arranged at equal intervals in the circumferential direction, and the four divided retaining portions 45 are equal in shape and size. This prevents variation in the strength of the four divided retaining portions 45 (greater variation), making it easier to ensure the strength of the crimping portion 29 as a whole.

In addition, in the structure of this example, the first hub element 22 is fitted to the mating shaft portion 28 of the second hub element 23 with a clearance fit that does not cause any radial rattle. In other words, the mating shaft portion 28 is not pressed into the center hole 24, and the outer peripheral surface of the mating shaft portion 28 and the inner peripheral surface of the center hole 24 are fitted to each other without any rattle without any tightening margin. Therefore, the inner ring raceway 11a on the axially outer side does not deform (expand) in the radially expanding direction when the mating shaft portion 28 is inserted into the center hole 24. In addition, the restrained surface 25 of the first hub element 22 that is pressed by the restraining portion 31 is located axially outward of the inner ring raceway 11a on the axially outer side, and is located in a position that overlaps radially with the rotating flange 12, which has a large radial rigidity. Therefore, the inner ring raceway 11a on the axially outer side is sufficiently prevented from deforming in the radially expanding direction when the restraining portion 31 presses down the restrained surface 25. Therefore, in this example of the hub unit bearing 1, it is easy to apply the appropriate preload to the rolling elements 4a and 4b.

In addition, in the structure of this example, the first face spline 26 of the first hub element 22 and the second face spline 30 of the second hub element 23 are meshed together, preventing relative rotation (creep) between the first hub element 22 and the second hub element 23.

In addition, in the manufacturing method of the hub unit bearing 1 of this example, the machining surface portion 40 of the pressing die 39 that constitutes the rocking and pressing device 38 is formed in a simple conical convex shape. This reduces the machining cost of the machining surface portion 40, and the pressing die 39 can be manufactured inexpensively. Therefore, the manufacturing cost of the hub unit bearing 1 can be reduced accordingly.

Furthermore, because the machined surface portion 40 is a conical convex surface, the same die 39 can be used to form the crimped portion even when manufacturing multiple hub unit bearings with different diameters. This eliminates the need to replace the die 39 of the rocking and crimping device 38 every time the model number of the hub unit bearing to be manufactured changes. Therefore, the manufacturing costs of the hub unit bearing 1 can be reduced from these aspects as well.

In addition, in the manufacturing method of the hub unit bearing 1 of this example, when the cylindrical portion 36 is machined into the crimped portion 29, the pressing die 39 rotates around the rotation axis L based on the frictional force acting on the contact portion between the machined surface portion 40 and the cylindrical portion 36. That is, the contact of the machined surface portion 40 with the cylindrical portion 36 is a rolling contact, but in this example, since the apex of the imaginary cone surface including the machined surface portion 40 exists at the intersection point P between the central axis C of the second hub element 23 and the rotation axis L, it is possible to prevent differential slippage from occurring at the contact portion between the machined surface portion 40 and the cylindrical portion 36 (crimped portion 29). Specifically, it is possible to prevent circumferential slippage from occurring at any radial position of this contact portion. Therefore, wear and heat generation at the contact portion between the machined surface portion 40 and the cylindrical portion 36 (crimped portion 29) can be sufficiently suppressed.

In addition, in the manufacturing method of the hub unit bearing 1 of this example, tests are performed in advance, and from the obtained test results, an angle α (and β) is selected that results in the clamping surface 35 of the clamping portion 31 having a shape that conforms to the clamped surface 25. The clamping portion 31 is then formed using the angle α selected in this manner. This ensures a sufficient contact area of the clamping surface 35 with the clamped surface 25, and prevents the contact surface pressure of the clamping surface 35 with the clamped surface 25 from becoming excessively large. This increases the bonding strength between the first hub element 22 and the second hub element 23, and the durability of the clamping portion 31.

Furthermore, in this example, the crimped portion 29 including the holding portion 31 and the inward flange portion 32 is formed by axially crushing the cylindrical portion 36 having the axial slits 37 at multiple locations in the circumferential direction. Therefore, when forming the crimped portion 29, it is possible to prevent a large circumferential stress from being applied to the cylindrical portion 36 (crimped portion 29), and to make the crimped portion 29 less susceptible to damage such as cracks.

[Second Example of the Embodiment]
A second embodiment of the present invention will be described with reference to FIGS.

In this example, the first hub element 22a has a first face spline 26a, which is a circumferentially uneven portion, on the radially inner portion of the axially inner end face, and a first flat portion 54 on the radially outer portion of the axially inner end face. That is, the first flat portion 54 is present in a portion of the axially inner end face of the first hub element 22a that is located radially outward, on one radial side, from the first face spline 26a. The first flat portion 54 is composed of a circular flat surface centered on the central axis of the first hub element 22a, and is provided around the entire circumference of the radially outer portion of the axially inner end face of the first hub element 22a.

In addition, in this example, the second hub element 23a has a second face spline 30a, which is a circumferentially uneven portion, on the radially inner portion of the axially outer end face of the base 27, and a second flat portion 55 on the radially outer portion of the axially inner end face of the base 27. That is, the second flat portion 55 is present in a portion of the axially outer end face of the base 27 that is located radially outward, on one radial side, from the second face spline 30a. The second flat portion 55 is composed of a circular flat surface centered on the central axis of the second hub element 23a, and is provided around the entire circumference of the radially outer portion of the axially outer end face of the base 27.

In this example, as shown in Figure 11, the first hub element 22a and the second hub element 23a are combined to form the hub 3, and the first flat portion 54 and the second flat portion 55 are brought into contact (flat contact). The first face spline 26a and the second face spline 30a are meshed to form a rotation prevention engagement portion that prevents relative rotation between the first hub element 22a and the second hub element 23a. However, in this state, the opposing axial side surfaces of the first face spline 26a and the second face spline 30a are not brought into contact with each other. Specifically, the bottom surface (the surface facing inward in the axial direction) of the recess that constitutes the first face spline 26a and the tip surface (the surface facing outward in the axial direction) of the protrusion that constitutes the second face spline 30a are opposed in the axial direction with a gap therebetween, and the tip surface (the surface facing inward in the axial direction) of the protrusion that constitutes the first face spline 26a and the bottom surface (the surface facing outward in the axial direction) of the recess that constitutes the second face spline 30a are opposed in the axial direction with a gap therebetween.

That is, in this example, the axial distance between the double row inner ring raceways 11a, 11b (for example, the axial distance between the large flange surfaces of the double row inner ring raceways 11a, 11b) is not restricted based on the meshing of the first face spline 26a and the second face spline 30a. In this example, the axial distance between the double row inner ring raceways 11a, 11b can be precisely restricted (adjusted) based on the abutment of the first flat portion 54 and the second flat portion 55, which are easier to form with higher precision than the first face spline 26a and the second face spline 30a. This makes it easier to bring the preload applied to the multiple rolling elements 4a, 4b closer to the target value, and suppresses the variation in the preload.

In this example, the first flat surface portion 54 is located radially outward from the first face spline 26a, and the second flat surface portion 55 is located radially outward from the second face spline 30a. However, when implementing the present invention, it is also possible to adopt a configuration in which the first flat surface portion is located radially inward from the first face spline, and the second flat surface portion is located radially inward from the second face spline.
The other configurations and effects are similar to those of the first embodiment.

[Third Example of the Embodiment]
A third embodiment of the present invention will be described with reference to FIGS.

In the hub unit bearing 1a of this example, the axially inner end face 48 of the first hub element 22b and the axially outer end face 49 of the base 27 of the second hub element 23b are each formed of a plane perpendicular to the axial direction. Specifically, the axially inner end face 48 of the first hub element 22b is formed of a circular ring-shaped plane centered on the central axis of the first hub element 22b. Also, the axially outer end face 49 of the base 27 of the second hub element 23b is formed of a circular ring-shaped plane centered on the central axis of the second hub element 23b. These end faces 48, 49 are in planar contact with each other. That is, in the structure of this example, there is no anti-rotation engagement portion between the end faces 48 and 49 by a face spline as in the first example of the embodiment. In this example as well, the axial distance between the double row inner ring raceways 11a, 11b can be precisely regulated (adjusted) based on the planar contact between the end faces 48 and 49.

In the structure of this example, the first hub element 22b has, at a plurality of circumferential locations on the radially inner end of the axially outer surface that align with the radially outer portion (portion present in the holding portion 31) of the slit 34 of the second hub element 23b, engagement protrusions 50 that protrude axially outward from adjacent portions on both sides in the circumferential direction. In the structure of this example, the portion of the radially inner end of the axially outer surface of the first hub element 22b that is circumferentially removed from the engagement protrusions 50 becomes the held surface 25. In the structure of this example, with the held surface 25 held down by the holding portion 31, each of the engagement protrusions 50 is engaged with the radially outer portion of the slit 34 without any circumferential rattle, forming a rotation prevention engagement portion that prevents relative rotation between the first hub element 22b and the second hub element 23b.

When manufacturing the hub unit bearing 1a of this embodiment, before assembling the hub unit bearing 1z1 before forming the crimped portion 29, the engaging protrusions 50 are formed at multiple circumferential locations on the radially inner end of the axially outer surface of the first hub element 22b. Then, in a state where the hub unit bearing 1z1 is assembled, the circumferential phase of the engaging protrusions 50 of the first hub element 22b and the axial slits 37 of the second hub element 23z1 before forming the crimped portion 29 are matched. Then, in this state, as shown in FIG. 14(A)→FIG. 14(B), the cylindrical portion 36 is crushed in the axial direction using the rocking crimping device 38. As a result, the crimped portion 29 including the radial intermediate portion 57, the holding portion 31, and the inward flange portion 32 is formed, and the axial slit 37 is made into the slit 34, and the slit 34 is engaged with the engaging protrusions 50 to couple and fix the first hub element 22b and the second hub element 23b.
The other configurations and effects are similar to those of the first embodiment.

[Fourth and fifth examples of the embodiment]
A fourth and fifth example of the embodiment of the present invention will be described with reference to FIGS.

Each of the fourth and fifth embodiments is an example in which the present invention is applied to a hub unit bearing for a driving wheel.
In the fourth example of the embodiment shown in Figure 15 (A), the inner surface of the second hub element 23c is provided with splines 52 for engaging a drive shaft driven by an engine or electric motor as a drive source so as to be able to transmit torque.
In the fifth example of the embodiment shown in Figure 15 (B), the axially inner surface of the second hub element 23d is provided with a face spline 53 for torque transmittance engagement with a driving member, such as an outer ring for a constant velocity joint, which is driven by an engine or an electric motor as a driving source.
The other configurations and effects are similar to those of the first embodiment.

[Sixth Example of the Embodiment]
A sixth embodiment of the present invention will be described with reference to FIGS.

In the hub unit bearing 1b of this example (see FIG. 16B), the slits 34a provided at four equally spaced locations in the circumferential direction of the crimped portion 29a of the second hub element 23e each open to the axially and radially outer sides of the crimped portion 29a. These slits 34a connect the boundary edge portion 56 to the outside.

In this example, the radially inner portion of the crimped portion 29a, specifically, the portion of the crimped portion 29a located radially inner than the slit 34a, is composed of a circular crimped annular portion 58 that is connected around the entire circumference. The crimped annular portion 58 is composed of the radially inner portion of the radial intermediate portion 57a of the crimped portion 29a and the inward flange portion 32a. Therefore, the radially inner portion of the radial intermediate portion 57a and the inward flange portion 32a are connected around the entire circumference.

When manufacturing the hub unit bearing 1b of this example, the second hub element 23z2 is prepared before the crimped portion 29a is formed, as shown in FIG. 16(A). Each of the axial slits 37a provided at four equally spaced locations in the circumferential direction of the cylindrical portion 36a of the second hub element 23z2 has an L-shaped cross-sectional shape. That is, each of the axial slits 37a opens to the outer peripheral surface, the axially outer end face, and the axially outer portion of the inner peripheral surface of the cylindrical portion 36a. A ring-shaped annular portion 59 that is connected around the entire circumference is present on the radially inner portion of the axially inner portion of the cylindrical portion 36a.

Then, as shown in Figure 16(A), the hub unit bearing 1z2 is assembled before the crimped portion 29a is formed. Then, in this state, as shown in Figure 16(A) → Figure 16(B), the cylindrical portion 36a is crushed in the axial direction using the rocking crimping device 38. This forms the crimped portion 29a with the radial intermediate portion 57a, the retaining portion 31, and the inward flange portion 32a, and also converts the axial slit 37a into the slit 34a and the annular portion 59 into the crimped annular portion 58.

In the hub unit bearing 1b of this embodiment as described above, the radially inner portion of the crimped portion 29a is configured by the annular crimped portion 58 that is connected over the entire circumference. This makes it easy to ensure the strength of the crimped portion 29a.
The other configurations and effects are similar to those of the first embodiment.

The present invention can be implemented by appropriately combining the configurations of the above-described embodiments within a range that does not cause any contradiction.
Furthermore, the present invention is not limited to hub unit bearings that use tapered rollers as rolling elements, but can also be applied to hub unit bearings that use balls as rolling elements.
In addition, when using an oscillating crimping device to process a cylindrical portion into a crimped portion, the present invention also allows the abutment portion between the processed surface portion and the cylindrical portion to exist on a straight line that inclines in a direction toward the axially outward direction as it moves radially outward, within an imaginary plane including the central axis of the second hub element and the rotation axis of the stamping die.

REFERENCE SIGNS LIST 1, 1a, 1b, 1z, 1z1, 1z2 hub unit bearing 2 outer ring 3 hub 4a, 4b rolling elements 5a, 5b outer ring raceway 6 stationary flange 7 support hole 8 knuckle 9 through hole 10 bolt 11a, 11b inner ring raceway 12 rotating flange 13 pilot portion 14 mounting hole 15 braking rotating element 16 stud 17 through hole 18 wheel 19 through hole 20 nut 21a, 21b cage 22, 22a, 22b first hub element 23, 23a, 23b, 23c, 23d, 23z, 23z1, 23z2 second hub element 24 central hole 25 clamped surface 26 first face spline 27 base 28 mating shaft portion Reference Signs List 29, 29a, 29z Crimping portion 30 Second face spline 31 Holding portion 32, 32a Inward flange portion 33 Side surface 34, 34a Slit 35 Holding surface 36, 36a Cylindrical portion 37, 37a Axial slit 38 Swinging and pressing device 39 Pressing die 40 Machined surface portion 41 Test assembly 42 Support stand 43 Support tube member 44 Test piece 45 Split holding portion 46 Split inward flange portion 47 Missing portion 48 End surface 49 End surface 50 Engagement protrusion 51 Split crimping portion 52 Spline 53 Face spline 54 First flat portion 55 Second flat portion 56 Boundary edge portion 57, 57a Radial intermediate portion 58 Crimped annular portion 59 Annular portion REFERENCE SIGNS LIST 100 Hub unit bearing 101 Outer ring 102 Hub 103 Rolling elements 104a, 104b Outer ring raceway 105 Stationary flange 106 Support hole 107a, 107b Inner ring raceway 108 Rotating flange 109 Pilot portion 110 Mounting hole 111 First hub element 112 Second hub element 113 Base portion 114 Fitting shaft portion 115 Crimping portion

Claims (15)

an outer ring having a double row outer ring raceway on an inner circumferential surface;
A hub having a double row inner ring raceway on its outer circumferential surface;
and a plurality of rolling elements are disposed for each row between the double row outer ring raceways and the double row inner ring raceways,
the hub comprises a first hub element and a second hub element;
the first hub element has an axially outer inner ring raceway of the double row inner ring raceways on an outer peripheral surface, a center hole at a radial center portion, a held surface on an axially outer side surface, and a boundary edge portion at a boundary between the center hole and the held surface,
the second hub element comprises a base portion having an axially inner inner ring raceway of the double row inner ring raceways on its outer circumferential surface, a fitting shaft portion extending axially outward from a radially inner portion of the base portion and inserted into the central hole of the first hub element, and a crimping portion adjacent to the axially outer side of the fitting shaft portion and pressing against the pressed surface,
The crimping portion has a slit that connects the boundary edge portion to the outside ,
The slit is open to an axially outer side and a radially outer side of the crimped portion,
A portion of the crimped portion located radially inward from the slit is continuous over the entire circumference.
Hub unit bearing. The slits are provided at a plurality of locations in the circumferential direction of the crimped portion.
The hub unit bearing according to claim 1 . The slits are provided at a plurality of locations that are equally spaced in the circumferential direction of the crimped portion.
The hub unit bearing according to claim 2 . The held surface is inclined in a direction toward the axially outward side as it goes toward the radially outward side,
The axially outer side surface of the crimped portion is configured as a flat surface perpendicular to the central axis of the second hub element.
The hub unit bearing according to any one of claims 1 to 3 . The crimping portion has a radially intermediate portion connected to an axially outer end portion of the fitting shaft portion, a pressing portion protruding radially outward from the radially intermediate portion and pressing down the pressed surface, and an inward flange portion protruding radially inward from the radially intermediate portion.
The hub unit bearing according to any one of claims 1 to 4 . Between the first hub element and the second hub element, there is a rotation prevention engagement portion that prevents relative rotation between the first hub element and the second hub element.
The hub unit bearing according to any one of claims 1 to 5 . The anti-rotation engagement portion is configured by meshing a first face spline provided on an axially inner end surface of the first hub element with a second face spline provided on an axially outer end surface of the base of the second hub element.
The hub unit bearing according to claim 6 . a first flat surface portion which is present on an axially inner end face of the first hub element at a portion located radially on one side of the first face spline and which is constituted by an annular flat surface centered on the central axis of the first hub element; and a second flat surface portion which is present on an axially outer end face of the base of the second hub element at a portion located radially on one side of the second face spline and which is constituted by an annular flat surface centered on the central axis of the second hub element,
the first flat surface portion and the second flat surface portion are in contact with each other, and axial side surfaces of the first face spline and the second face spline that face each other are not in contact with each other;
The hub unit bearing according to claim 7 . The anti-rotation engagement portion is configured by engaging each of the slits with an engagement protrusion provided on the first hub element.
The hub unit bearing according to any one of claims 6 to 8 . A vehicle equipped with a hub unit bearing,
The hub unit bearing is a hub unit bearing according to any one of claims 1 to 9 .
vehicle. A method for manufacturing a hub unit bearing according to any one of claims 1 to 9 ,
obtaining the second hub element before forming the crimped portion, the second hub element including a cylindrical portion extending axially outward from an axially outer end of the fitting shaft portion and having an axial slit extending axially at at least one location in a circumferential direction;
inserting the fitting shaft into the central hole of the first hub element;
a pressing die having a convex curved machined surface portion that is supported for free rotation about a rotation axis inclined with respect to the central axis of the second hub element and has a linear generatrix inclined with respect to the rotation axis, wherein a circumferential portion of the machined surface portion is pressed against an axially outer end face of the cylindrical portion while rotating the pressing die about the central axis of the second hub element to form the crimped portion by crushing the cylindrical portion in the axial direction, and the first hub element and the second hub element are joined and fixed together by pressing the pressed surface with the crimped portion.
A manufacturing method for a hub unit bearing. In the step of connecting and fixing the first hub element and the second hub element, within an imaginary plane including the central axis of the second hub element and the rotation axis, the abutment portion between the cylindrical portion and the processed surface portion exists on a straight line perpendicular to the central axis of the second hub element.
A method for manufacturing a hub unit bearing according to claim 11 . In the step of connecting and fixing the first hub element and the second hub element, a vertex of an imaginary conical surface including the processed surface portion is located at an intersection point between a central axis of the second hub element and the rotation axis.
A method for manufacturing a hub unit bearing according to claim 11 or 12 . A test is performed to examine the relationship between the inclination angle of the rotation axis with respect to the central axis of the second hub element and the shape of the axially inner side surface of the crimping portion, and based on the results of the test, the inclination angle is determined so that the axially inner side surface of the crimping portion can be shaped to conform to the clamped surface, and the determined inclination angle is used to connect and fix the first hub element and the second hub element.
A method for manufacturing a hub unit bearing according to any one of claims 11 to 13 . A manufacturing method for a vehicle equipped with a hub unit bearing, comprising:
The hub unit bearing is manufactured by the manufacturing method of the hub unit bearing according to any one of claims 11 to 14 .
A method for manufacturing a vehicle.

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