JP2016200212A - Hub unit and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the lowering of degree of adhesion between an inner ring member and an inner shaft by forming a caulking part.SOLUTION: A hub unit includes an inner shaft having a small diameter part 23 on a part of axial direction and an inner ring member fitted to an outer circumferential surface 23c of the small diameter part 23 and fixes the inner ring member to the inner shaft by means of a caulking part 24 which plastically deforms an axially directional end part of the inner shaft to the axially directional outer side. Therein, on either one side of the outer circumferential surface 23c of the small diameter part 23 and an inner circumferential surface of the inner ring member fitted to the outer circumferential surface 23c, at least a swollen surface 23c1 which is convexly curved toward the other side of the outer circumferential surface of the small diameter part 23 and the inner circumferential surface of the inner ring member and is swollen in a state before forming the caulking part 24, a cylindrical cylinder surface 23c2 which is arranged on an axially directional both sides of the swollen surface 23c1 and has a constant radius while setting an axial center of the hub unit as a center and a connection surface 23c3 which is arranged between the swollen surface 23c1 and the cylinder surface 23c2, is convexly curved and smoothly connects the swollen surface 23c1 and the cylinder surface 23c2 are provided.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a hub unit and a manufacturing method thereof.

A hub unit is used to rotatably support the wheels of an automobile with respect to a suspension device. The hub unit includes a rolling bearing and a hub wheel having a cylindrical hub shaft that serves as a race member of the rolling bearing (see, for example, Patent Document 1).
The hub shaft described in Patent Document 1 includes an inner shaft that integrally has a flange portion, and an inner ring member that is fitted to the outer peripheral surface of a small-diameter portion that constitutes a part of the axial direction of the inner shaft. The position of the inner ring member in the axial direction is fixed by a caulking portion in which an axial end portion of the inner shaft is plastically deformed radially outward.

JP 2014-24506 A

  As shown in FIG. 6, when the caulking portion 124 is formed by plastically deforming the axial end portion of the inner shaft 121 radially outward, the small diameter portion 123 of the inner shaft 121 is distorted radially inward, and the small diameter portion 123 A gap S may be formed between the outer peripheral surface and the inner peripheral surface of the inner ring member 132, and the degree of adhesion between them may be reduced. Such a decrease in the degree of adhesion leads to a decrease in the holding force of the inner ring member 132 and causes creep of the inner ring member 132, which is not preferable.

  In view of the above circumstances, the present invention provides a hub unit that can suppress a decrease in the degree of adhesion between an inner ring member and a small diameter portion of an inner shaft due to the formation of a crimped portion, and a method for manufacturing the same. Objective.

  The present invention includes an inner shaft having a small-diameter portion in a part of the axial direction, and an inner ring member fitted to the outer peripheral surface of the small-diameter portion, and the axial end portion of the inner shaft is plastically deformed radially outward. A hub unit in which the inner ring member is fixed to the inner shaft by a crimped portion, and either one of the outer peripheral surface of the small diameter portion and the inner peripheral surface of the inner ring member fitted to the outer peripheral surface Includes a bulging surface that bulges in a convex shape toward the other side of the outer peripheral surface of the small-diameter portion and the inner peripheral surface of the inner ring member, at least before the caulking portion is formed, and the bulging surface. Arranged on both sides in the axial direction of the exit surface, disposed between the cylindrical surface of the hub unit having a constant radius around the axis of the hub unit, the bulging surface and the cylindrical surface, curved in a concave shape and It has a connecting surface that smoothly connects the bulging surface and the cylindrical surface.

  ADVANTAGE OF THE INVENTION According to this invention, the fall of the adhesiveness of the inner ring member and the small diameter part of an inner shaft by forming a crimping part can be suppressed.

It is sectional drawing of the hub unit which concerns on the 1st Embodiment of this invention. It is sectional drawing which expands and shows the inner shaft and inner ring member of the hub unit shown by FIG. It is sectional drawing which shows the state before fitting an inner ring member to the small diameter part of an inner shaft. It is explanatory drawing which shows the bulging surface, cylindrical surface, and connection surface which were formed in the inner shaft. It is sectional drawing which expands and shows the inner axis | shaft and inner ring member of the hub unit which concern on the 2nd Embodiment of this invention. It is sectional drawing which expands and shows the inner shaft and inner ring member of the hub unit which concerns on a prior art.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a cross-sectional view of a hub unit according to the first embodiment of the present invention. In this specification, the left-right direction in FIG. 1 is referred to as the axial direction of the hub unit 10, the left side in FIG. 1 is referred to as the vehicle outer side (or axially outside), and the right side is referred to as the vehicle inner side (or axially inside).

The hub unit 10 supports, for example, the wheels of an automobile so as to be rotatable with respect to the suspension device on the vehicle body side. The hub unit 10 includes a rolling bearing 11 and a hub wheel 12 having a ring member of the rolling bearing 11.
The hub wheel 12 has a hub shaft 20 and a flange portion 26. The hub shaft 20 is formed in a cylindrical shape and functions as an inner ring of the rolling bearing 11. The hub shaft 20 has an inner shaft 21 and an inner ring member 32.

  The inner shaft 21 integrally includes a large diameter portion 22, a small diameter portion 23, and a caulking portion 24. The large diameter portion 22 of the inner shaft 21 is disposed on the vehicle outer side, and the small diameter portion 23 is disposed on the vehicle inner side. The small diameter portion 23 is continuously formed on the inner side in the axial direction of the large diameter portion 22. Further, the outer diameter of the small diameter portion 23 is smaller than the outer diameter of the large diameter portion 22. The caulking portion 24 is plastically deformed so that the axial end portion of the inner shaft 21 on the vehicle inner side with respect to the small diameter portion 23 is bent outward in the radial direction.

The inner ring member 32 is fitted so that the inner peripheral surface 32 c is in close contact with the outer peripheral surface 23 c of the small diameter portion 23.
The flange portion 26 protrudes radially outward from the radially outer end portion of the large diameter portion 22. A plurality of bolt holes 26 a penetrating in the thickness direction are formed in the flange portion 26 in the circumferential direction. Each bolt hole 26a is fixed by press-fitting a hub bolt 27 for attaching a wheel or a brake disk (not shown).

The rolling bearing 11 is a double row ball bearing. The rolling bearing 11 includes an outer ring 31, the hub shaft 20 that forms the inner ring, a plurality of balls (rolling elements) 33, and a cage 34.
The outer ring 31 has a pair of outer ring raceway surfaces 31a and 31b on its inner peripheral surface. The pair of outer ring raceway surfaces 31a and 31b are arranged side by side in the axial direction. A fixing flange 35 for attaching the hub unit 10 to a vehicle body side member (not shown) supported by the suspension device is formed on the outer peripheral surface of the outer ring 31.

The inner ring member 32 of the hub axle 20 has an inner ring raceway surface 32a on the outer peripheral surface thereof. The inner ring raceway surface 32a faces the radially inner side of the outer ring raceway surface 31a on the vehicle inner side.
The large diameter portion 22 of the inner shaft 21 in the hub shaft 20 has an inner ring raceway surface 22b on the outer peripheral surface thereof. The inner ring raceway surface 22b faces the inner side in the radial direction of the outer ring raceway surface 31b on the vehicle outer side.

The plurality of balls 33 are rotatably arranged between the outer ring raceway surface 31a and the inner ring raceway surface 32a and between the outer ring raceway surface 31b and the inner ring raceway surface 22b. Therefore, the plurality of balls 33 are arranged in two rows in the axial direction.
A pair of cages 34 are provided corresponding to the balls 33 in two rows. Each cage 34 holds a plurality of balls 33 in each row at a predetermined interval in the circumferential direction.

FIG. 2 is an enlarged sectional view showing the inner shaft 21 and the inner ring member 32 of the hub unit 10 shown in FIG.
The inner ring member 32 has an inner peripheral surface 32 c that extends substantially parallel to the axis C of the hub unit 10. On the vehicle inner side and the vehicle outer side from the inner peripheral surface 32c, rounded surfaces 32d and 32e that are curved in an arc shape are formed, respectively.

  On the other hand, the small-diameter portion 23 of the inner shaft 21 has an outer peripheral surface 23 c that extends substantially parallel to the axis C of the hub unit 10. An outer peripheral surface 24d of the caulking portion 24 formed on the vehicle inner side with respect to the small diameter portion 23 is curved in an arc shape along the round surface 32d of the inner ring member 32, and is in close contact with the round surface 32d. Further, a rounded surface 23e that is curved in an arc shape along the rounded surface 32e of the inner ring member 32 and is in close contact with the rounded surface 32e is formed on the vehicle outer side of the outer peripheral surface 23c of the small diameter portion 23.

  The inner peripheral surface 32c of the inner ring member 32 is fitted into the outer peripheral surface 23c of the small-diameter portion 23 in a state of being tightly fitted, and is in close contact with the outer peripheral surface 23c. That is, a fastening allowance is provided between the inner diameter dimension of the inner ring member 32 and the outer diameter dimension of the small diameter portion 23. Therefore, the inner ring member 32 is restricted from relative rotation in the circumferential direction with respect to the small diameter portion 23, and the occurrence of creep is prevented.

FIG. 3 is a cross-sectional view showing a state before the inner ring member 32 is fitted to the small diameter portion 23 of the inner shaft 21.
The axial end 24 ′ of the inner shaft 21 extends along the axial direction continuously to the vehicle inner side of the small diameter portion 23 before the crimped portion 24 (see FIG. 2) is formed by plastic deformation. Then, as shown by an arrow X, after the inner ring member 32 is fitted into the small diameter portion 23, the axial end portion 24 'of the inner shaft 21 is moved radially outward (in the direction of arrow a) by using a jig not shown. ) To form a crimped portion 24 having a shape along the rounded surface 32d. Thereby, the hub wheel 12 of the hub unit 10 is manufactured.

  When the caulking portion 24 is formed by plastically deforming the axial end 24 ′ of the inner shaft 21, the small diameter portion 23 of the inner shaft 21 is opposite to the direction a in which the caulking portion 24 bends (inward in the radial direction). Some distortion occurs. Conventionally, as shown in FIG. 6, a gap S is generated between the inner ring member 132 and the small diameter portion 123 due to distortion of the small diameter portion 123 of the inner shaft 121, and the outer peripheral surface of the small diameter portion 123 and the inner peripheral surface of the inner ring member 132. There is a problem that the degree of adhesion with the inner ring member 121 decreases and the holding force of the inner ring member 132 by the inner shaft 121 decreases.

As shown in FIGS. 3 and 4, in the hub unit 10 of the present embodiment, the outer peripheral surface 23 c of the small diameter portion 23 includes the bulging surface 23 c 1, the cylindrical surface 23 c 2, and the connection surface 23 c 3 at the stage of manufacturing the inner shaft 21. Formed to have.
The bulging surface 23c1 is curved to bulge outwardly in the radial direction. Specifically, the bulging surface 23c1 of the present embodiment bulges in a circular arc shape in the radially outward direction.

Further, the cylindrical surface 23c2 is disposed on the vehicle inner side and the vehicle outer side with respect to the bulging surface 23c1, and is formed in a cylindrical shape having a constant radius around the axis C of the hub unit 10.
Furthermore, the connection surface 23c3 is disposed between the bulging surface 23c1 and the cylindrical surface 23c2, and is formed to be concavely curved. The connection surface 23c3 smoothly connects the bulging surface 23c1 and the cylindrical surface 23c2 so that the cross-sectional shape does not change suddenly between the bulging surface 23c1 and the cylindrical surface 23c2. The connection surface 23c3 of the present embodiment is a rounded surface having an arcuate cross section.

The connecting surface 23c3 on the vehicle inner side is disposed on the vehicle outer side from the starting point P of the crimping portion 24 (the boundary between the outer peripheral surface 23c of the small diameter portion 23 and the rounded surface 24d). However, the connection surface 23c3 may overlap with the starting point P.
The radius of curvature of the cross-sectional arc of the bulging surface 23c1 can be set to 250 mm, for example. Further, the radius of curvature of the cross-section arc of the connection surface 23c3 at the boundary between the bulging surface 23c1 and the cylindrical surface 23c2 can be set to 10 mm, for example.

  By forming the swollen surface 23c1 as described above on the outer peripheral surface 23c of the small diameter portion 23, even if the small diameter portion 23 is distorted radially inward by forming the crimping portion 24, the entire outer peripheral surface 23c is the inner ring member 32. The inner peripheral surface 32c can be brought into close contact with an interference fit. Therefore, the adhesion between the outer peripheral surface 23c of the small diameter portion 23 and the inner peripheral surface 32c of the inner ring member 32 does not decrease, and the holding force of the inner ring member 32 can be maintained.

  In the present specification, “adhesion degree” refers to the degree of close contact between the outer peripheral surface 23c of the small diameter portion 23 and the inner peripheral surface 32c of the inner ring member 32. For example, both the 23c and 32c are in contact with no gap. The size of the area can be used as an index. Further, the “holding force” refers to a force by which the inner shaft 21 holds the inner ring member 32 so that the inner shaft 21 and the inner ring member 32 do not rotate relative to each other, for example, the outer peripheral surface 23 c of the small diameter portion 23 and the inner ring member 32. The frictional force generated between the inner peripheral surface 32c can be used as an index.

  As shown in FIG. 4, the bulging amount H of the bulging surface 23c1, that is, the height of the apex of the bulging surface 23c1 with respect to the cylindrical surface 23c2, is the inner circumference of the inner ring member 32 even if the small diameter portion 23 is distorted radially inward. The size is set such that the interference fit is maintained between the surface 32c. Specifically, the amount of distortion of the small-diameter portion 23 when the crimped portion 24 is formed can be experimentally obtained, and the bulging amount H of the bulging surface 23c1 can be set based on the amount of distortion. For example, the bulging amount H can be set within a range of 5.0 μm to 70.0 μm. Further, the cylindrical surface 23c2 disposed on the vehicle inner side and the vehicle outer side with respect to the bulging surface 23c1 is also formed with an outer diameter dimension that provides an interference fit with the inner peripheral surface 32c of the inner ring member 32.

  Generally, the outer peripheral surface 23c of the small diameter portion 23 of the inner shaft 21 is formed by polishing or cutting. Conventionally, the outer peripheral surface of the small-diameter portion does not have a bulging surface or a connection surface as in the present embodiment, so that only the cylindrical surface is processed. In this embodiment, the bulging surface 23c1 and the connection surface 23c3 are formed by the same process as the cylindrical surface 23c2 by polishing or cutting. Therefore, the number of steps does not increase as compared with the conventional method when the bulging surface 23c1 and the connection surface 23c3 are formed.

FIG. 5 is an enlarged cross-sectional view showing an inner shaft and an inner ring member of a hub unit according to the second embodiment of the present invention.
In the first embodiment, the outer peripheral surface 23c of the small diameter portion 23 of the inner shaft 21 has the bulging surface 23c1, but in the present embodiment, the inner peripheral surface 32c of the inner ring member 32 has the bulging surface 32c1. ing. Further, the inner peripheral surface 32c of the inner ring member 32 has a cylindrical surface 32c2 having a certain radius on the vehicle outer side and the vehicle inner side with respect to the bulging surface 32c1. Furthermore, the inner peripheral surface 32c of the inner ring member 32 has a connection surface 32c3 that smoothly connects both the bulging surface 32c1 and the cylindrical surface 32c2.

The bulging surface 32c1 and the connecting surface 32c3 differ from the bulging surface 23c1 and the connecting surface 32c3 in the first embodiment only in the direction of bulging or indenting, and the shape (bulging amount, etc.) is the same as in the first embodiment. The bulge surface 23c1 and the connection surface 32c3 can be the same.
Also in this embodiment, the bulging surface 32c1, the cylindrical surface 32c2, and the connection surface 32c3 of the inner ring member 32 are formed in the same process by polishing or cutting. Therefore, the number of processes does not increase with the formation of the bulging surface 32c1 and the connection surface 32c3.

  In the present embodiment, the caulking portion 24 is formed by plastically deforming the axial end portion 24 ′ of the inner shaft 21, and even if the small diameter portion 23 is distorted inward in the radial direction, the bulging surface is formed in the distorted portion. 32c1 enters, and an interference fit state in which the inner peripheral surface 32c of the inner ring member 32 and the outer peripheral surface 23c of the small diameter portion 23 are in close contact with each other is maintained. Accordingly, the adhesion between the outer peripheral surface 23c of the small diameter portion 23 and the inner peripheral surface 32c of the inner ring member 32 is not impaired, and the holding force of the inner ring member 32 can be maintained.

  In addition, illustration of the bulging surfaces 23c1 and 32c1 in FIGS. 3 to 5 and illustration of the gap S in FIG. 6 described in the above embodiment are exaggerated for easy understanding. . Therefore, those dimensions, as well as the relative proportions with other parts, are different from the actual ones.

The present invention is not limited to the above-described embodiment, and can be appropriately changed within the scope of the invention described in the claims.
The bulging surface may be formed on a surface substantially parallel to the axis C after forming the crimped portion, or may have a shape bulging in the radial direction. Further, the bulging surface is not limited to a circular arc shape having a constant curvature radius, and may have a shape with a changing curvature radius. The connecting surface is not limited to a circular arc shape with a constant radius of curvature, and may have a shape with a variable radius of curvature.
The rolling bearing of the hub unit is not limited to a ball bearing but can be a roller bearing.
The inner shaft of the hub unit is not limited to a cylindrical shape, and may be a solid shape.

  10: Hub unit, 11: Rolling bearing, 12: Hub wheel, 21: Inner shaft, 23: Small diameter portion, 23c: Outer peripheral surface, 23c1: Swelled surface, 23c2: Cylindrical surface, 23c3: Connection surface, 24: Caulking portion, 32: inner ring member, 32c: inner peripheral surface, 32c1: bulging surface, 32c2: cylindrical surface, 32c3: connection surface, H: bulging amount

Claims (5)

A caulking portion including an inner shaft having a small diameter portion in a part of the axial direction and an inner ring member fitted to an outer peripheral surface of the small diameter portion, and an axial end portion of the inner shaft being plastically deformed radially outward. A hub unit that fixes the inner ring member to the inner shaft by:
At least one of the outer peripheral surface of the small-diameter portion and the inner peripheral surface of the inner ring member fitted to the outer peripheral surface is in a state before forming the caulking portion, and the outer peripheral surface of the small-diameter portion and the A bulging surface that bulges in a convex shape toward the other side of the inner peripheral surface of the inner ring member, and is disposed on both sides in the axial direction of the bulging surface, and has a constant radius centered on the axis of the hub unit. A hub unit having a cylindrical cylindrical surface, and a connection surface that is disposed between the bulging surface and the cylindrical surface and that is curved in a concave shape and smoothly connects the bulging surface and the cylindrical surface. .   The hub unit according to claim 1, wherein the bulging amount of the bulging surface is set within a range of 5.0 to 70.0 μm. A caulking portion including an inner shaft having a small diameter portion in a part of the axial direction and an inner ring member fitted to an outer peripheral surface of the small diameter portion, and an axial end portion of the inner shaft being plastically deformed radially outward. A manufacturing method of a hub unit that fixes the inner ring member to the inner shaft by:
One of the outer peripheral surface of the small-diameter portion and the inner peripheral surface of the inner ring member fitted to the outer peripheral surface, a bulge surface that curves and bulges toward the other side, and the bulge surface A cylindrical surface having a constant radius, and disposed between the bulging surface and the cylindrical surface, and curved in a concave shape to smoothly smooth the bulging surface and the cylindrical surface. Forming a connection surface to be connected;
Fitting the inner peripheral surface of the inner ring member to the outer peripheral surface of the small-diameter portion;
And a step of plastically deforming an axial end portion of the inner shaft to form a crimped portion.   The hub unit manufacturing method according to claim 3, wherein the bulging surface, the cylindrical surface, and the connection surface are formed in the same process by polishing.   The hub unit manufacturing method according to claim 3, wherein the bulging surface, the cylindrical surface, and the connection surface are formed in the same process by cutting.

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