JP2023059592A - Method for manufacturing hub unit bearing - Google Patents

Abstract

To provide a method for manufacturing a hub unit bearing that can grind a fitting surface to which an inner ring is fitted and a cylindrical surface of a shaft end part with a diameter smaller than the fitting surface at one time while suppressing generation of a small end height due to drop out of abrasive grains.SOLUTION: A hub ring has a shaft end part that includes: a cylindrical surface with a diameter smaller than a fitting surface; and a concave surface formed between the fitting surface and the cylindrical surface, at the outer peripheral surface thereof. The concave surface has a curvature radius that is 30 or more times larger than a difference between respective radii of the fitting surface and the cylindrical surface. The fitting surface, the concave surface and the cylindrical surface are ground together with at least a seal slide contact surface that is formed axially inward of a wheel fitting flange of the hub ring.SELECTED DRAWING: Figure 2

Description

The present invention relates to a method of manufacturing a hub unit bearing.

In a conventional hub unit bearing, the inner ring is fitted on the hub ring, and the axial end portion of the hub ring extending inward in the axial direction is bent radially outward to form a caulking portion. Some are fixed to the hub wheel in the axial direction to form a hub.

For example, in Patent Document 1, as shown in FIG. describes that deformation of the inner ring 110 due to crimping is minimized by providing a small diameter surface 103 having a small diameter of about 0.2 to 1.0 mm. Also in Patent Document 2, a stepped portion having a concave arcuate cross-sectional shape is formed at the boundary between the outer peripheral surface of the cylindrical portion formed at the shaft end of the hub wheel and the outer peripheral surface of the small diameter stepped portion. , that this stepped portion is used as a base point for deformation during crimping.

Such a structure in which the outer peripheral surface of the shaft end is smaller in diameter than the inner ring fitting surface shortens the press-fitting distance when press-fitting the inner ring into the hub ring, thereby improving productivity. It is possible to prevent the occurrence of press-fitting flaws on the outer peripheral surface of the shaft end, which is a source of stress concentration, and lead to an improvement in the fatigue strength of the crimped portion.

In general, hub wheels are processed by grinding from the seal sliding contact surface at the base of the wheel mounting flange to the inner ring fitting surface at once using a formed grindstone formed using a diamond wheel. The degree of concentricity is increased to suppress flange deflection of the bearing assembly (see Patent Document 3).

JP-A-2005-249047 JP-A-2003-74571 Japanese Patent Application Laid-Open No. 2004-092830

By the way, when grinding the hub wheel 100 having the corner portion 104 shown in FIG. In addition, it is difficult to supply coolant, and grinding burns and cracks are likely to occur on the machined surface of the stepped portion of the corner portion 104 . For this reason, the outer peripheral surface of the hub wheel 100 as shown in FIG. was separately processed such as turning and grinding.

Therefore, if there is a slight misalignment between the inner ring fitting surface 102 and the small diameter surface 103 that is the portion to be crimped, the bending of the portion to be crimped will not be uniform during crimping. There is a possibility that the machining force will vary, making it difficult to control the machining conditions, and that the strength of the crimped portion after crimping will also vary in the circumferential direction.

The present invention has been made in view of the above-mentioned problems, and its object is to suppress the occurrence of small end height due to falling off of abrasive grains, and to provide a fitting surface where an inner ring is fitted and a smaller diameter than the fitting surface. To provide a method for manufacturing a hub unit bearing capable of grinding the cylindrical surface of the shaft end of the shaft at one time.

The above objects of the present invention are achieved by the following configurations.
(1) an outer ring having a double-row outer ring raceway on its inner peripheral surface;
A hub wheel having a wheel mounting flange axially outwardly and a cylindrical fitting surface formed axially inwardly, and at least one inner ring externally fitted to the fitting surface of the hub wheel, a hub having, on its outer peripheral surface, a double-row inner ring raceway facing the double-row outer ring raceway;
a plurality of rolling elements arranged to be free to roll between the double-row outer ring raceway and the double-row inner ring raceway,
The hub wheel is caulked by bending a shaft end extending axially inwardly from the fitting surface in a state where the at least one inner ring is fitted onto the fitting surface. A method of manufacturing a hub unit bearing, forming a portion to axially secure the at least one inner ring to the hub ring, the method comprising:
The outer peripheral surface of the axially inner shaft end portion of the hub wheel has a cylindrical surface having a diameter smaller than that of the fitting surface and a concave curved surface formed between the fitting surface and the cylindrical surface. ,
the radius of curvature of the concave curved surface is 30 times or more the difference between the radii of the fitting surface and the cylindrical surface;
The fitting surface, the concave curved surface, and the cylindrical surface are ground at least together with a seal sliding contact surface formed axially inward of the wheel mounting flange of the hub wheel,
A method for manufacturing a hub unit bearing.
(2) the double-row inner ring raceway is formed on each of the hub ring and the inner ring;
The fitting surface, the concave curved surface, and the cylindrical surface are ground together with the inner ring raceway and the seal sliding contact surface,
(1) A method for manufacturing a hub unit bearing.
(3) the concave curved surface is formed to connect the fitting surface and the cylindrical surface;
At the ridge between the concave curved surface and the fitting surface, the angle of the tangent line of the concave curved surface with respect to the axial direction is 15° or less.
A method for manufacturing a hub unit bearing according to (1) or (2).
(4) the axial end portion of the hub wheel further includes a convex curved surface formed between the fitting surface and the concave curved surface;
The convex curved surface and the concave curved surface are formed so as to connect the fitting surface and the cylindrical surface,
The radius of curvature of the convex curved surface is 30 times or more the difference between the radii of the fitting surface and the cylindrical surface.
A method for manufacturing a hub unit bearing according to (1) or (2).

According to the method for manufacturing a hub unit bearing of the present invention, the fitting surface where the inner ring is fitted and the cylindrical surface of the shaft end portion having a smaller diameter than the fitting surface while suppressing the occurrence of small end height due to falling off of abrasive grains. and can be ground at once. As a result, misalignment between the fitting surface and the cylindrical surface does not occur, and the crimped portion can be crimped with uniform strength in the circumferential direction.

1 is a cross-sectional view of a hub unit bearing according to one embodiment of the present invention; FIG. FIG. 4 is a cross-sectional view showing the hub wheel before the inner ring is crimped and fixed; FIG. 3 is an enlarged cross-sectional view of part III of FIG. 2 ; 4 is an enlarged cross-sectional view corresponding to FIG. 3, showing a hub ring of a hub unit bearing according to a modification of the invention; FIG. FIG. 5 is a cross-sectional view showing a hub ring before the inner ring is caulked and fixed in a conventional hub unit bearing.

A method of manufacturing a hub unit bearing according to one embodiment of the present invention will be described in detail below with reference to the drawings.

As shown in FIG. 1, a driven wheel hub unit bearing 10 of the present embodiment supports a wheel, which is a driven wheel, rotatably with respect to a suspension device such as a knuckle. A hub 30 which is a rotating wheel is rotatably supported on the inner diameter side via a plurality of rolling elements 13 .

The outer ring 20 has a mounting flange 22 coupled and fixed to a knuckle (not shown) constituting a suspension system on its outer peripheral surface, and has double-row outer ring raceways 21a and 21b on its inner peripheral surface. The mounting flange 22 is provided with a female threaded hole 23 for coupling the outer ring 20 to the knuckle.

The hub 30 is formed by fitting an inner ring 32 onto a cylindrical fitting surface 37 formed axially inwardly of a small-diameter stepped portion 34 of a hub wheel 31 , and connecting and fixing the inner ring 32 with a crimp portion 33 . . Further, the hub 30 has double-row inner ring raceways 35a and 35b on the outer peripheral surface of the hub wheel 31 and the outer peripheral surface of the inner ring 32 facing the double-row outer ring raceways 21a and 21b. A wheel mounting flange 36 for mounting a wheel and a brake rotor constituting a wheel is provided at a portion axially outward of the hub wheel 31 and protruding axially outward beyond the axially outward end opening of the outer ring 20 . is provided.
A plurality of rolling elements 13 are rotatably arranged between each of the outer ring raceways 21a and 21b and each of the inner ring raceways 35a and 35b. Also, the rolling elements 13 in each row are held by a retainer 14 at regular intervals in the circumferential direction.

The term "outward in the axial direction" as used herein relates to the axial direction of the hub unit bearing, and is the outboard side that is the outer side in the width direction of the vehicle body when the hub unit bearing 10 is assembled to the vehicle. This is the inboard side, which is the inner side in the width direction of the vehicle body.

A bearing space 15 in which each rolling element 13 is installed between the inner peripheral surface of the outer ring 20 and the outer peripheral surface of the hub 30 is closed by a seal ring 16 at the end opening on the axially outward side. The end opening on the inner side is closed by an end cap 17 .

A slinger 19 to which an encoder 18 is fixed is fitted and fixed to the outer peripheral surface of the shoulder portion of the inner ring 32 .

FIG. 2 is a cross-sectional view showing the hub wheel before the inner ring is caulked and fixed. That is, as described above, the hub wheel 31 includes the wheel mounting flange 36, the seal sliding contact surface 38, the outer ring raceway 35a, the small diameter stepped portion 34, and the cylindrical portion in order from the axially outward to the axially inward direction. A fitting surface 37 and a shaft end portion 39 which is a crimped portion are formed.

The seal sliding contact surface 38 is formed continuously from the axially inner side surface of the wheel mounting flange 36, and the seal lip of the seal ring 16 is in sliding contact therewith. A cylindrical fitting surface 37 is formed axially inward from the small-diameter stepped portion 34, and the inner ring 32 is fitted thereon.

The shaft end portion 39 is a cylindrical portion extending axially inward from the cylindrical fitting surface 37 , and has a cylindrical surface 40 having a smaller diameter than the fitting surface 37 and the fitting surface 37 on the outer peripheral surface. and a concave curved surface 41 formed so as to connect with the cylindrical surface 40 .

Therefore, in the hub wheel 31, the inner ring 32 is fitted onto the fitting surface 37 and abutted against the small-diameter stepped portion 34, and the axial end portion 39 is bent radially outward to form the caulked portion 33. Then, the inner ring 32 is fixed to the hub ring 31 in the axial direction.

Here, as shown enlarged in FIG. 3, in the hub wheel 31 before caulking, the concave curved surface 41 has a concave arcuate cross section, and extends axially outward from the boundary portion 41a with the cylindrical surface 40. It is formed so as to gradually increase in diameter. The curvature radius R of the concave curved surface 41 is 30 times or more (approximately 35 times in this embodiment) the difference d (=d1-d2) between the radii d1 and d2 of the fitting surface 37 and the cylindrical surface 40 . At the ridge 42 between the concave curved surface 41 and the fitting surface 37, the angle α of the tangent line S of the concave curved surface 41 with respect to the axial direction of the hub wheel 31 (fitting surface 37) is 15° or less (in this embodiment, less than 14°).

In the hub wheel 31 before caulking, the fitting surface 37, the concave curved surface 41, and the cylindrical surface 40 are ground at the same time as the inner ring raceway 35a, the small-diameter stepped portion 34, and the seal sliding contact surface 38.

The seal sliding contact surface 38, the outer ring raceway 35a, the small diameter stepped portion 34, and the cylindrical fitting surface 37 are subjected to heat treatment such as induction hardening after hot forging to form a hardened layer T (see cross in FIG. 2). hatched portion) is formed.

As a result, the boundary 41a between the concave curved surface 41 and the cylindrical surface 40 does not have a corner where stress is concentrated, and the shaft end 39 can be bent while smoothly expanding in diameter by caulking.

Further, by setting the curvature radius R of the concave curved surface 41 to be 30 times or more the difference d (=d1-d2) between the radii d1 and d2 of the fitting surface 37 and the cylindrical surface 40, the fitting surface 37 and the concave curved surface The angle α of the tangent line S of the concave curved surface 41 with respect to the axial direction can be made small at the ridge 42 with 41 . As a result, even if the fitting surface 37, the concave curved surface 41, and the cylindrical surface 40 are ground at the same time, it is difficult for small end height to occur near the concave curved surface 41 side of the fitting surface 37 due to falling off of abrasive grains of the formed grindstone. In addition, since it is easy to supply coolant to the concave curved surface 41, the occurrence of grinding burns and cracks on the machined surface can be suppressed.

Edge load occurs at the contact part between the grinding wheel and the work (grinding is a process with high normal force, so elastic deformation occurs at the contact part between the grinding wheel and the work), and the abrasive grains at the edge load part This is a phenomenon in which the workpiece swells (becomes left uncut) as a result of the destruction of the binder and the falling off of the abrasive grains. Therefore, by reducing the change in interference in the axial direction of the grindstone, it is possible to prevent the occurrence of a small width.

Grinding burns and cracks also occur when the workpiece temperature rises sharply due to insufficient supply of coolant. The corner of the work has a small heat capacity, and the surface of the grindstone for grinding the corner of the work is the corner. Since the grindstone rotates at high speed accompanied by rotating air currents, it is difficult for the coolant to reach the corners of the grindstone, which causes grinding burns and cracks. Also in this case, grinding burn and cracks can be prevented by reducing the change in interference in the axial direction of the grindstone.

Further, in the present embodiment, since the angle α of the tangent line S of the concave curved surface 41 with respect to the axial direction is as small as 15° or less at the ridge 42 between the fitting surface 37 and the concave curved surface 41, the fitting surface 37 and the concave curved surface Even if the 41 and the cylindrical surface 40 are ground at the same time, the height of the small end due to the falling off of the abrasive grains is less likely to occur, and the supply of the above coolant is even easier, so the occurrence of grinding burns and cracks on the machined surface is further suppressed. be done.

Therefore, the fitting surface 37, the concave curved surface 41, and the cylindrical surface 40 can be ground together with the inner ring raceway 35a and the seal sliding contact surface 38, so that misalignment between the fitting surface 37 and the cylindrical surface 40 does not occur. The crimped portion 33 can also be crimped with uniform strength in the circumferential direction.

In addition, since the axial end portion 39, which is the portion to be crimped, is ground, the effect of improving the surface strength is obtained by improving the surface roughness, and the strength of the crimped portion 33 after crimping is improved. and prevent fatigue fracture.

FIG. 4 is an enlarged cross-sectional view corresponding to FIG. 3, showing a hub wheel of a hub unit bearing according to a modification of the invention.
In this modification, the axial end portion 39 of the hub wheel 31 further includes a convex curved surface 43 formed between the cylindrical fitting surface 37 and the concave curved surface 41 . Therefore, the convex curved surface 43 and the concave curved surface 41 connect the fitting surface 37 and the cylindrical surface 40 with a curve having an S-shaped cross section. The convex curved surface 43 has a convex circular cross section, and the curvature radius R1 of the convex curved surface 43 is 30 times or more the difference d between the radii d1 and d2 of the fitting surface 37 and the cylindrical surface 40. FIG.

As a result, on both sides of the boundary 41a between the concave curved surface 41 and the cylindrical surface 40 and the boundary 43a between the convex curved surface 43 and the fitting surface 37, ridges are not formed, and the convex curved surfaces are formed. 43 and the concave curved surface 41 are smoothly continuous, so even if the fitting surface 37, the convex curved surface 43, the concave curved surface 41, and the cylindrical surface 40 are ground at the same time, the occurrence of small end height due to falling off of abrasive grains is eliminated. It is easy to supply coolant, and the occurrence of grinding burns and cracks on the machined surface is suppressed.

Therefore, even in the modified example, the fitting surface 37, the convex curved surface 43, the concave curved surface 41, and the cylindrical surface 40 can be ground together with the inner ring raceway 35a and the seal sliding contact surface 37. The crimping portion 33 can also be crimped with a uniform strength in the circumferential direction without causing misalignment on the outer peripheral surface of the crimping portion 39 .

It should be noted that the present invention is not limited to the above-described embodiments, and can be modified, improved, etc. as appropriate.
For example, in the above embodiment, the hub has an inner ring and a hub ring each having an inner ring raceway. It can be tightened. In this case, the fitting surface, concave curved surface, and cylindrical surface of the hub wheel are ground together with at least the seal sliding contact surface formed axially inwardly of the wheel mounting flange of the hub wheel.
Also, in the above embodiments, balls are used as the rolling elements, but other rolling elements such as tapered rollers may be used.
Furthermore, in the above embodiment, the hub unit bearing on the side of the driven wheel has been described, but the present invention can also be applied to the hub unit bearing on the side of the driving wheel.

10 Hub unit bearing 13 Rolling element 20 Outer ring 21a, 21b Outer ring raceway 30 Hub 31 Hub ring 32 Inner ring 33 Crimping portion 34 Small diameter stepped portion 35a, 35b Inner ring raceway 37 Cylindrical fitting surface 39 Shaft end 40 Cylindrical surface 41 Concave Curved surface 42 Ridge 43 Convex curved surface

Claims (4)

an outer ring having a double-row outer ring raceway on its inner peripheral surface;
A hub wheel having a wheel mounting flange axially outwardly and a cylindrical fitting surface formed axially inwardly, and at least one inner ring externally fitted to the fitting surface of the hub wheel, a hub having, on its outer peripheral surface, a double-row inner ring raceway facing the double-row outer ring raceway;
a plurality of rolling elements arranged to be free to roll between the double-row outer ring raceway and the double-row inner ring raceway,
The hub wheel is caulked by bending a shaft end extending axially inwardly from the fitting surface in a state where the at least one inner ring is fitted onto the fitting surface. A method of manufacturing a hub unit bearing, forming a portion to axially secure the at least one inner ring to the hub ring, the method comprising:
The outer peripheral surface of the axially inner shaft end portion of the hub wheel has a cylindrical surface having a diameter smaller than that of the fitting surface and a concave curved surface formed between the fitting surface and the cylindrical surface. ,
the radius of curvature of the concave curved surface is 30 times or more the difference between the radii of the fitting surface and the cylindrical surface;
The fitting surface, the concave curved surface, and the cylindrical surface are ground at least together with a seal sliding contact surface formed axially inward of the wheel mounting flange of the hub wheel,
A method for manufacturing a hub unit bearing. The double-row inner ring raceway is formed on each of the hub ring and the inner ring,
The fitting surface, the concave curved surface, and the cylindrical surface are ground together with the inner ring raceway and the seal sliding contact surface,
2. A method of manufacturing a hub unit bearing according to claim 1. The concave curved surface is formed to connect the fitting surface and the cylindrical surface,
At the ridge between the concave curved surface and the fitting surface, the angle of the tangent line of the concave curved surface with respect to the axial direction is 15° or less.
3. A method of manufacturing a hub unit bearing according to claim 1 or 2. the axial end portion of the hub wheel further includes a convex curved surface formed between the fitting surface and the concave curved surface;
The convex curved surface and the concave curved surface are formed to connect the fitting surface and the cylindrical surface,
The radius of curvature of the convex curved surface is 30 times or more the difference between the radii of the fitting surface and the cylindrical surface.
3. A method of manufacturing a hub unit bearing according to claim 1 or 2.

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