JPH11129703A - Rolling bearing unit for wheel supporting - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure the rolling contact fatigue life of a first inner ring raceway track and to realize low cost structure. SOLUTION: A hub 2b made of carbon steel with a carbon content >=0.45 wt.% and an inner ring 3 made of high carbon steel are coupled with a calking part 19 formed at the edge part of the hub 2n. An inclined grid part containing a first inner ring raceway track 7 of a hub 2b is hardened by quenching. An inner ring 3 is hardened by quenching to the core part. A part for forming at least the calking part 19 of the hub 2b is kept raw without conducting quenching.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The rolling bearing unit for supporting wheels according to the present invention is used to rotatably support wheels of an automobile with respect to a suspension device.

[0002]

2. Description of the Related Art The wheels of an automobile are supported on a suspension system by rolling bearing units for supporting wheels. FIG. 17 shows a first example of a rolling bearing unit for supporting a wheel, which has been widely practiced conventionally. The rolling bearing unit 1 for supporting a wheel includes a hub 2, an inner ring 3, an outer ring 4, and a plurality of rolling elements 5,5. Of these, the outer end portion of the outer peripheral surface of the hub 2 (the outside refers to the side that is outwardly offset in the width direction when assembled to an automobile, and is the left side in each of the drawings except for FIGS. 4 to 6. The side closer to the center is called the inner side, and is the right side in each of the drawings except for FIGS. 4 to 6.), A first flange 6 for supporting the wheels is formed. A first inner raceway 7 is formed on the outer peripheral surface of the intermediate portion of the hub 2, and a step 8 having a smaller outer diameter is formed on the inner end of the hub 2.

The inner ring 3 having a second inner raceway 9 formed on the outer peripheral surface thereof is fitted on the step portion 8. A male thread 10 is formed at the inner end of the hub 2, and the tip of the male thread 10 protrudes inward from the inner end surface of the inner race 3. The inner ring 3 is held at a predetermined position of the hub 2 by clamping the inner ring 3 between a nut 11 screwed to the male screw portion 10 and a step surface 12 of the step portion 8. . A locking recess 14 is formed on the outer peripheral surface of the distal end of the male screw portion 10. After tightening the nut 11 with a predetermined torque, the nut 1
The nut 11 is prevented from loosening by caulking a part of the part 1 that matches the locking concave part 14 inward in the diameter direction.

A first outer raceway 15 facing the first inner raceway 7 and a second outer raceway 16 facing the second inner raceway 9 are formed on the inner peripheral surface of the outer race 4. doing. And between the first and second inner raceways 7 and 9 and the first and second outer raceways 15 and 16, the rolling elements 5,
5 are provided in plurality. In the illustrated example, balls are used as the rolling elements 5 and 5. However, in the case of a heavy-weight rolling bearing unit for an automobile, tapered rollers may be used as these rolling elements.

In order to assemble the above-described rolling bearing unit 1 for supporting a wheel into an automobile, the outer ring 4 is fixed to a suspension system by a second flange 17 formed on the outer peripheral surface of the outer ring 4 and the first The wheel is fixed to the flange 6 of.
As a result, the wheels can be rotatably supported by the suspension device.

Further, US Pat. No. 5,490,732 discloses a rolling bearing unit 1 for supporting wheels having a structure as shown in FIG. In the case of the second example of this conventional structure, the first inner ring 41 and the second inner ring 3 are externally fitted on the outer peripheral surface of the hub 18 provided with the first flange 6 on the outer peripheral surface. A crimping portion 19 is formed by bending a portion of the inner end of the hub 18 that protrudes inward from the inner end surface of the second inner race 3 outward in the diametrical direction.
And the first flange 6 on the outer peripheral surface of the intermediate portion of the hub 18.
The first and second inner rings 41 and 3 are held between the stepped surface 12a provided at the base of the first and second inner rings 41 and 3. That is, the caulking portion 19 is formed by caulking and expanding the cylindrical portion formed at the inner end portion of the hub 18 inwardly protruding from the second inner ring 3 in the diametrically outward direction. 19 presses the first and second inner rings 41 and 3 toward the step surface 12a.

[0007]

In the case of the first example of the conventional structure shown in FIG. 17, the operation of forming the locking concave portion 14 at the tip of the male screw portion 10 and the operation of changing a part of the nut 11 in the diametrical direction are described. Work to crimp inward is required. For this reason, the parts manufacturing operation and the assembling operation of the wheel supporting rolling bearing unit 1 are troublesome, and the cost is increased.

In the case of the structure of the second example shown in FIG.
It is necessary to form a caulking portion 19 on the hub 18 for connecting and fixing the first and second inner rings 41 and 3 to the hub 18. Therefore, the hub 18 needs to be made of a material capable of forming the caulking portion 19. In the case of the structure of the second example shown in FIG. 18, the hub 18 itself is not provided with an inner raceway, and the first and second inner races 41, 3 externally fitted to the hub 18 are provided on the outer peripheral surfaces thereof. , The second inner raceways 7 and 9 are provided, so that the caulking portion 19 is used as a material of the hub 18.
Can be used, and carbon steel having a carbon content of less than 0.45% by weight can be used. However, a large load is applied to the second inner ring 3 fitted to the hub 18 in association with the processing of the caulking portion 19 as described above. For this reason, the second inner ring 3 is deformed, and the (positive or negative) internal clearance of the rolling bearing unit becomes
It may deviate from the desired value. If the internal gap deviates from an appropriate value, the rolling fatigue life of the second inner raceway 9 formed on the outer peripheral surface of the second inner race 3 is reduced.

Such a disadvantage is caused by combining the structure shown in FIG. 17 with the structure shown in FIG. 18 and providing the hub 2 with the first flange 6 and the first inner raceway 7 so that the inner race 3
This also occurs in the case of a structure in which is fixed to the hub 2 by the caulking portion 19. Further, when such a structure is adopted, like the hub 18 having the conventional structure shown in FIG.
If the hub 2 is made of carbon steel having a carbon content of less than 0.45% by weight, the hardness of the first inner raceway 7 cannot be sufficiently increased, and sufficient durability cannot be secured. In view of such circumstances, the present invention has been made to provide a low-cost and sufficiently durable rolling bearing unit for supporting a wheel.

[0010]

In the rolling bearing unit for supporting a wheel according to the present invention, the rolling bearing unit according to the first aspect has a first flange on an outer peripheral surface at one end and a first inner ring on an outer peripheral surface at an intermediate portion. A track formed on each of the hubs, a step formed on the other end of the hub, and having a smaller outer diameter than a portion forming the first inner raceway, and a second inner race formed on an outer peripheral surface of the hub. An inner ring that forms a raceway and is externally fitted to the stepped portion, a first outer raceway facing the first inner raceway and a second outer raceway facing the second inner raceway on the inner peripheral surface, A second flange is formed on the outer peripheral surface, an outer ring formed respectively, and a plurality of rolling elements provided respectively between the first and second inner ring tracks and the first and second outer ring tracks. At the other end of the hub, at least at the part protruding from the inner ring fitted to the step The caulking part formed by caulking and expanding the formed cylindrical part outward in the diameter direction suppresses the inner ring externally fitted to the step toward the step surface of this step, and the inner ring externally fitted to this step It is connected and fixed to the hub. In particular, in the rolling bearing unit for supporting wheels according to claim 1, the hub has a carbon content of 0.45% by weight.
It is made of the above carbon steel, and at least the first inner raceway portion is hardened by quenching and at least the cylindrical portion is left raw without being subjected to the quenching, and the inner race is made of bearing steel or the like. Made of high carbon steel and hardened to the core.

When the above-described rolling bearing unit for supporting wheels is implemented, the carbon content of the carbon steel constituting the hub is, for example, 0.45 to 1.10% by weight. In this case, at least the portion of the hub where the first inner raceway is formed is quenched and hardened, and the hardness of the cylindrical portion formed at the other end of the hub is Hv200 to 300 (claim 2). The content of carbon in the carbon steel constituting the hub is, for example, 0.45 to 0.60% by weight. In this case, the hub is made by forging this carbon steel, and at least the cylindrical portion is not annealed after forging the hub. The content of carbon in the carbon steel constituting the hub is, for example, 0.60 to 1.10% by weight. In this case, the hub is formed by forging this carbon steel, and the cylindrical portion is annealed after forging the hub (claim 4). Preferably, at least at the corner of the step, a continuous portion of a cylindrical outer peripheral surface for externally fitting and fixing the inner ring and a step surface abutting the end surface of the inner ring has a cross-section of a quarter circle. An arc-shaped curved surface (corner R) is formed. Then, the radius of curvature of the cross section of this curved surface portion is set to 2.5 ± 1.5 mm
Regulate within the range.

According to a fifth aspect of the present invention, there is provided a hub having a first flange formed on an outer peripheral surface at one end, and a step formed from an intermediate portion in the axial direction to the other end on the outer peripheral surface of the hub. And a first inner ring formed on the outer peripheral surface to form a first inner ring raceway and externally fitted to one end of the step portion, and a second inner ring raceway formed on the outer peripheral surface to form a second inner raceway on the other end side of the step portion. A second inner race fitted externally, a first outer raceway facing the first inner raceway on the inner peripheral surface and a second outer raceway facing the second inner raceway on the inner peripheral surface, a second outer raceway on the outer peripheral surface, An outer ring formed with a flange, and a plurality of rolling elements provided between the first and second inner ring raceways and the first and second outer raceways, respectively. At the end, at least a cylindrical portion formed at a portion protruding from the second inner ring which is externally fitted to the other end side of the step portion is diametrically outward. By the swaging portion formed by expanding, the first and second inner rings externally fitted to the step portion are pressed down toward the step surface of this step portion, and the first and second inner rings externally fitted to the step portion are suppressed. The inner ring is connected and fixed to the hub. In particular,
In the rolling bearing unit for supporting a wheel according to claim 5, the hub hardens at least one end portion of the step portion including a step surface of the step portion by quenching, and at least the cylindrical portion has The first and second inner rings are made of high carbon steel such as bearing steel and hardened to the core by hardening without being subjected to quenching.

When the rolling bearing unit for supporting wheels according to the fifth aspect is implemented, the hub is made of carbon steel, and the carbon content in the carbon steel is preferably 0.20 to 1%. 0.1% by weight. Then, in a state before the cylindrical portion is crimped outward in the diameter direction, the hardness of the portion not subjected to the quench hardening treatment is Hv200 to Hv200.
Set to 300.

[0014]

The operation of the wheel supporting rolling bearing unit of the present invention configured as described above to rotatably support the wheel with respect to the suspension is the same as that of a conventionally known wheel supporting rolling bearing unit. is there. In particular, in the case of the rolling bearing unit for supporting a wheel according to the present invention, cost reduction can be achieved while securing sufficient durability.

First, in the case of the invention described in claim 1 (and claims 2 to 4), the hub is made to have a carbon content of 0.45%.
It is made of carbon steel as described above, and at least the first inner ring raceway portion is hardened by a hardening process such as induction hardening, carburizing hardening, laser hardening and the like. Therefore, the rolling fatigue life (peeling life) of the first inner raceway surface can be sufficiently ensured regardless of the load repeatedly applied from the rolling elements. That is, in order to secure the above rolling fatigue life,
The hardness of the surface of the first inner raceway is increased (for example, H
_V 550-900). When the hardness of the surface portion is low, the rolling fatigue life of the first inner race is shortened. If the hub is made of carbon steel having a carbon content of less than 0.45% by weight, the required hardness cannot be obtained even if the first inner raceway portion is hardened. On the other hand, in the case of the invention described in claim 1, the hub is made of carbon steel having a carbon content of 0.45% by weight or more, and the first inner raceway portion is hardened by quenching. As a result, the hardness of the first inner raceway portion is sufficiently increased, and the rolling fatigue life of the first inner raceway portion can be ensured. Even when the rolling fatigue life of the first inner raceway portion is ensured in this way, the cylindrical portion provided on the hub is left raw without being subjected to the quenching process. Therefore, the processing of the swaged portion for connecting the hub and the inner ring is not troublesome.

Further, since the inner ring is made of high carbon steel such as bearing steel and is hardened and hardened to the core, even if a large load is applied to the inner ring due to the working of the caulking portion, the inner ring is formed. Can be prevented, and the (positive or negative) internal clearance of the rolling bearing unit can be prevented from deviating from a desired value. That is, when the cylindrical portion is swaged to form the swaged portion, it is necessary to apply a large diametrically outward load to the cylindrical portion. As a result, the inner peripheral surface and the end surface of the inner ring are
Large surface pressure acts. Therefore, if the hardness of the inner race is low, the inner race is deformed by the surface pressure, and the internal clearance of the rolling bearing unit deviates from a desired value. On the other hand, in the case of the invention described in claim 1, since the inner ring is made of high carbon steel such as bearing steel and hardened and hardened to the core, the hardness of the inner ring is sufficiently high. Despite the large surface pressure, the inner ring is prevented from being deformed, and the internal clearance can be maintained at a desired value. Further, it is possible to prevent the diameter of the second inner raceway from changing and to prevent the shape accuracy (roundness, cross-sectional shape) from deteriorating, thereby preventing the rolling fatigue life of the second inner raceway from decreasing.

Further, as in the rolling bearing unit for supporting a wheel described in claim 2, the carbon content in the carbon steel constituting the hub is set to 0.45 to 1.10% by weight, and the other end of the hub is provided. If the hardness of the cylindrical portion formed in the portion is set to Hv 200 to 300 before caulking, the hardness of the first inner ring raceway portion is ensured, and the work of caulking and expanding the cylindrical portion can be sufficiently performed. Incidentally, as in the invention described in claim 3,
The carbon content of the carbon steel constituting the hub is 0.45 to
If the content is 0.60% by weight, it is not necessary to perform annealing after forging. Further, the hardness of the cylindrical portion can be set to Hv200 to 300 by simply controlling the cooling rate after forging. On the other hand, as in the invention described in claim 4, the carbon content in the carbon steel constituting the hub is 0.60 to 1.10% by weight.
, Annealing is performed after forging.

Further, in the case of the invention described in claim 5, since the inner ring raceway is not provided on the hub itself, a caulked portion is easily formed as a material of the hub, and the carbon content is 0.45% by weight.
Less than carbon steel can be used. However, in the hub, at least one end of the step including the step surface of the step is hardened by a quenching process. For this reason, the step surface of the step portion, which is a portion for holding the first and second inner rings externally fitted to the step portion together with the caulking portion, and the step portion where concentrated stress is likely to be generated when the rolling bearing unit is used. The strength and durability of one end portion can be secured. On the other hand, since the cylindrical portion provided on the hub is not subjected to the quenching process and is left raw, processing of the caulked portion for connecting the hub to the first and second inner rings becomes troublesome. There is no. Further, the first and second inner rings which are fitted to the step portion are made of high carbon steel, and are hardened and hardened to the core. For this reason, the hardness of the first and second inner ring raceway portions can be ensured, and in the same manner as in the case of the inner ring constituting the invention described in claim 1 above, the swaging portion formed on the hub is processed. Accordingly, even when a large load is applied to the second inner ring, the deformation of the second inner ring can be prevented, and the internal gap of the rolling bearing unit can be prevented from deviating from a desired value. Further, it is possible to prevent the diameter of the second inner raceway formed on the outer peripheral surface of the second inner raceway from changing or from deteriorating the accuracy, thereby preventing the rolling fatigue life of the second inner raceway from decreasing. .

[0019]

1 to 4 show a first embodiment of the present invention, corresponding to claims 1 to 4. FIG. The wheel supporting rolling bearing unit 1a of the present example includes a hub 2b,
An inner ring 3, an outer ring 4, and a plurality of rolling elements 5, 5 are provided. Of the outer peripheral surface of the hub 2b,
A first flange 6 for supporting a wheel is formed.
A first inner raceway 7 is formed on the outer peripheral surface of the intermediate portion of the first inner race member 2b, and a step 8 having a smaller outer diameter is formed on the inner end. Such a hub 2b
Is integrally formed by forging a carbon steel material having a carbon content of 0.45 to 1.10% by weight.

FIG. 1 shows a partial outer peripheral surface of such a hub 2b.
, The first inner raceway 7, the base end of the first flange 6, and the step 8
(Part of the cylindrical outer peripheral surface which is a fitting portion of the inner ring 3 from the stepped surface 12 which is the abutting surface of the inner ring 3)
Is subjected to a quenching treatment such as induction hardening, carburizing quenching, or laser quenching, and the hardness of the portion is set to Hv5.
It is raised to about 50 to 900. In addition, among the above quenching processes, the induction hardening process is the most preferable because the processing cost is low. On the other hand, the carburizing and quenching treatment needs to perform a carbon-proof plating treatment on a portion that is not to be cured, so that the treatment cost increases. Also, the laser quenching process increases the equipment cost.

Incidentally, of the portions subjected to the quenching process indicated by the diagonal lattice, the first inner raceway 7 is subjected to a large surface pressure based on the contact with the rolling surface of the rolling element 5. Therefore, it is hardened to secure the rolling fatigue life. In addition, regardless of the moment load received from the first flange 6 to which the wheel is fixed,
The base is hardened to prevent deformation.
Further, of the base half portion of the step 8, a part of the outer peripheral surface of the step 8 is irrespective of the fitting pressure of the inner ring 3 and the radial load received by the inner ring 3 from the plurality of rolling elements 5. ,
The hardening is performed to prevent the outer peripheral surface of the step 8 from being deformed and to prevent the occurrence of fretting wear on the outer peripheral surface of the step 8 which is a fitting portion with the inner ring 3. Let it. The stepped surface 12 of the stepped portion 8 prevents the stepped surface 12 from being deformed irrespective of an axial load applied to the inner ring 3 by a caulking operation described later. This step surface 1 which is the contact surface with the outer end surface
Second, it is cured to prevent occurrence of fretting wear. Further, a corner R portion which is a continuous portion between the outer peripheral surface of the step portion 8 and the step surface 12 is hardened in order to prevent deformation due to stress concentration. Preferably, this corner R
The radius of curvature of the cross section of the part is regulated within the range of 2.5 ± 1.5 mm. If the radius of curvature of this portion is less than 1 mm, there is a possibility that damage such as cracks may occur due to stress concentration. On the other hand, if the radius of curvature of the above portion exceeds 4 mm, it tends to interfere with the inner peripheral edge of the end of the inner ring 3, and the rolling bearing unit for supporting the wheel becomes difficult.

The axial position of the inner end of the quench hardened layer (point A in FIG. 1) indicated by the diagonal lattice is the axial position of the center of the plurality of rolling elements 5 arranged around the inner ring 3. Location (Figure 1
1 (the right side in FIG. 1), the axial position of a base end of the caulking portion 19 (a portion where the outer diameter of the caulking portion starts to become larger than the outer diameter of the step portion 8) (FIG. 1). (Point C in FIG. 1) (left side in FIG. 1). The reason for limiting the inner end position of the hardened hard layer in this way is to make the surface area of the hardened hard layer present on the outer peripheral surface of the step 8 as large as possible and to easily process the caulked portion 19. At the same time, the caulking portion 19 is prevented from being damaged due to the existence of the hardened hardened layer.
The quenched and hardened layer as described above may be formed discontinuously for each required portion. However, as in the present example shown in FIG.
If the adjacent hardened hardened layers are continuously formed, the strength and durability of the hub 2b can be improved.

A cylindrical portion 20 for forming a caulking portion 19 for fixing the inner ring 3 is formed at the inner end of the hub 2b. In the illustrated example, the wall thickness of the cylindrical portion 20 becomes smaller toward the leading edge in a state before the cylindrical portion 20 is swaged outward in the diametrical direction as shown in FIG. For this reason, in the case of the illustrated example, a tapered hole 21 is formed in the inner end surface of the hub 2b so that the inner diameter gradually decreases toward the concave portion. The inner ring 3 is a SUJ2
Made of high-carbon steel such as high-carbon chromium bearing steel, and hardened to the core.

The carbon content in the carbon steel constituting the hub 2b is set to 0.45 to 1.10% by weight as described above, and at least the cylindrical portion 20 formed at the other end of the hub 2b is formed. The hardness was Hv before caulking shown in FIG.
200 to 300. By satisfying such a condition, the hardness (Hv) required for the first inner raceway 7 portion is required.
550 to 900), and the work of caulking and widening the cylindrical portion 20 can be sufficiently performed. That is, the cylindrical portion 20
When the caulking portion 19 is formed by caulking the cylindrical portion 2
If the hardness of H.sub.0 exceeds Hv300, a crack is generated in the formed caulking portion 19 or the caulking becomes insufficient, so that the caulking portion 19 and the inner ring 3 do not adhere to each other and the inner ring 3 with respect to the hub 2b. Or the fastening force of the joint becomes small. In addition, the load required to form the caulking portion 19 becomes excessive, so that the raceway surfaces and the rolling elements 5, 5 are liable to be damaged such as indentations, and the dimensional accuracy of each portion is deteriorated. Raise the possibility of Further, machining of the hub 2b becomes difficult. In other words, the machining time is prolonged, the tool life is shortened, and the cost is increased.

If the carbon content in the carbon steel constituting the hub 2b exceeds 1.10% by weight, it becomes difficult to suppress the hardness of the cylindrical portion 20 to Hv300 or less, so that the hub 2b is formed. The upper limit of the carbon content in the carbon steel was set to 1.10% by weight. On the other hand, if the hardness of the cylindrical portion 20 does not reach Hv200, the hardness of the caulking portion 19 formed by caulking the cylindrical portion 20 cannot be ensured, and the fastening force of the inner ring 3 by the caulking portion 19 also increases. Run short. If the carbon content in the carbon steel constituting the hub 2b does not reach 0.45% by weight, the required hardness (Hv550-900) of the first inner raceway 7 cannot be secured, Since the life of one inner raceway 7 is reduced, the lower limit of the carbon content in the carbon steel forming the hub 2b is set to 0.45% by weight.

The hub 2b is manufactured by forging a carbon steel having a carbon content of 0.45 to 1.10% by weight for the above-described reason. .4
In the case of 5 to 0.60% by weight, it is not necessary to perform an annealing treatment after forging. That is, by simply controlling the cooling rate after forging, at least the hardness of the cylindrical portion 20 is set to Hv.
It is possible to fall within the range of 200 to 300. Therefore, after the hub 2b is formed by forging, the operation of forming the cylindrical portion 20 into the caulked portion 19 can be performed without performing the annealing process, and the rolling bearing for wheel support having the caulked portion 19 is provided. Units can be built at low cost.

On the other hand, when the content of carbon in the carbon steel constituting the hub 2b is set to 0.60 to 1.10% by weight, the hub 2b is formed by forging.
It is necessary to anneal. That is, even when the content of carbon in the carbon steel is set to 0.60 to 1.10% by weight, the hardness of the cylindrical portion 20 is increased by controlling the cooling rate after forging.
It is possible to make v200 to about 300. However,
Since the cooling rate needs to be considerably small (slow), it takes a long time and special equipment is also required. Therefore, it is preferable to perform annealing rather than to control the cooling rate in terms of securing production efficiency and simplifying production equipment. or,
Once the annealing is performed, the hardenability at the time of hardening the required portion of the hub 2b is improved. Therefore, after the hub 2b is manufactured by forging, an annealing process is performed.
At least the hardness of the cylindrical portion 20 is Hv200-300.
About. Incidentally, when the content of carbon in the carbon steel constituting the hub 2b is 0.60 to 1.10% by weight,
When the cooling rate after forging is not reduced and the annealing treatment is not performed, the content in the carbon steel as described above is 1.10.
The same problem as in the case where the content exceeds the weight% occurs. By the way,
When the content in the carbon steel exceeds 1.10% by weight, the hardness of the cylindrical portion 20 should be suppressed to Hv300 or less even when the cooling rate after forging is reduced or the annealing treatment is performed. Becomes difficult.

In order to fix the inner ring 3 to the inner end of the hub 2b and to widen the tip of the cylindrical portion 20 as described above, the hub 2b is fixed so as not to move in the axial direction. Then, as shown in FIG.
Press firmly against the tip of. At the center of the tip end surface (left end surface in FIG. 2) of the pressing die 22, a truncated cone-shaped convex portion 23 which can be pushed into the inside of the cylindrical portion 20 is formed.
A concave portion 24 having an arc-shaped cross section is formed around the entire periphery of the convex portion 23. The cross-sectional shape of the concave portion 24, the outer diameter R ₂₄ and the depth D ₂₄ are determined by forming the cylindrical portion 20 by plastically deforming the cylindrical portion 20 to form the caulking portion 19. While applying a force in the compression direction to the steel), it is regulated to form the caulked portion 19 having a predetermined shape and size. That is, the cross-sectional shape of the concave portion 24 is such that the cross-sectional shape of the caulking portion 19 obtained by plastically deforming the distal end portion of the cylindrical portion 20 by the concave portion 24 has a thickness dimension that increases from the base end portion toward the distal end portion. The compound curved surface has a curvature radius that becomes smaller toward the outer diameter side so that the thickness dimension becomes sharply smaller at the front end portion so as to gradually become smaller. The outer diameter R ₂₄ are the same as the outer diameter R ₁₉ of the crimped portion 19 to be formed, and the degree slightly smaller (R ₂₄ ≦ R ₁₉₎ than the outer diameter R ₁₉ of the crimped portion 19. Further, the depth D ₂₄ is set such that the crimping portion 19 is formed by sandwiching the distal end of the cylindrical portion 20 between the inner peripheral surface of the inner end of the inner race 3 and the inner end surface.
Is regulated so that a gap 25 remains between the front end surface of the inner ring 3 and the inner end surface of the inner ring 3.

When the pressing die 22 having the convex portions 23 and the concave portions 24 having the above-described shapes and dimensions is pressed against the distal end of the cylindrical portion 20, the distal end of the cylindrical portion 20 is swaged outward in the diameter direction. Thus, the caulking portion 19 can be formed. The inner ring 3 can be fixed to the hub 2b by clamping the inner ring 3 between the caulked portion 19 and the step surface 12 of the step 8 formed at the inner end of the hub 2b. In the case of the illustrated example, at the final stage of forming the caulked portion 19 by plastically deforming the inner end surface of the cylindrical portion 20, the inner surface of the concave portion 24 is diametrically connected to the outer diameter surface of the caulked portion 19. An inward compression force acts. Therefore, it is possible to effectively prevent the outer peripheral edge of the caulked portion 19 from being damaged such as a crack. Further, a curved surface portion 26 having an arc-shaped cross section is formed at a peripheral portion of an inner end opening of the inner ring 3 with which an outer diameter surface of a base end portion of the caulking portion 19 contacts. Therefore, the caulking portion 1
The radius of curvature of the base end portion of No. 9 does not decrease, and it becomes difficult for excessive stress to be applied to this base end portion.

As described above, in the case of the rolling bearing unit for supporting wheels of the present invention, the hub 2b is made of carbon steel having a carbon content of 0.45 to 1.10% by weight, and Since the inner raceway 7 is hardened by quenching, the rolling fatigue life of the surface of the first inner raceway 7 can be sufficiently ensured irrespective of the load repeatedly applied from the rolling elements 5, 5. On the other hand, the cylindrical portion 20 is left raw without being subjected to the quenching process. Therefore, the force required for plastically deforming the cylindrical portion 20 is unnecessarily large, or when the cylindrical portion 20 is plastically deformed, damage such as a crack is easily generated in the cylindrical portion 20. Absent.
Therefore, even when the hardness of the first inner raceway 7 is increased to secure the rolling fatigue life of the first inner raceway 7 as described above, caulking for connecting the hub 2b and the inner race 3 is performed. Processing of the part 19 is not troublesome. Moreover, since the inner ring 3 is made of high carbon steel such as bearing steel and is hardened and hardened to the core, even when a large load is applied to the inner ring 3 as a result of the processing of the caulking portion 19, the inner ring 3 is hardened. 3 can be prevented, and the internal clearance of the rolling bearing unit can be prevented from deviating from a desired value. Also, the inner ring 3
The diameter of the second inner raceway 9 formed on the outer peripheral surface of the second inner raceway 9 is prevented from changing or the accuracy is deteriorated, so that the rolling fatigue life of the second inner raceway 9 can be prevented from being shortened.

Further, in the case of the illustrated example, the caulking portion 19
The thickness of the cylindrical portion 20 for forming the hub 2b is reduced toward the leading edge, so that the hub 2b has a carbon content of 0.4.
Even when made of 5 to 1.10% by weight of carbon steel, the force required to form the caulking portion 19 by plastically deforming the distal end of the cylindrical portion 20 by the above-described pressing die 22 is too small. It does not grow. For this reason, damages such as cracks are generated in the caulking portion 19 during the caulking operation, or the diameter of the inner ring 3 is affected by the inner ring 3 fixed by the caulking portion 19, such as durability, such as preload and rolling fatigue life. This can more reliably prevent a force that greatly changes the force applied from acting. In particular, in the illustrated example, a compressive stress acts on the distal end portion of the caulking portion 19 and the radius of curvature of the base end portion of the caulking portion 19 is increased, so that the damage prevention of the caulking portion 19 is more effectively performed. I can do it. Note that the outer end opening of the space 27 in which the rolling elements 5 and 5 are provided is closed with a seal ring 28 and the inner end opening is closed with a lid 29, respectively.
This prevents dust from entering the space or leakage of lubricating oil and the like from this space.

Next, an explanation will be given of the appropriate values of the dimensions of each part in the case of realizing the structure as shown in FIGS.
Note that this value, when the wheel support rolling bearing unit incorporating a general passenger vehicle, i.e., an inner diameter of about r ₃ of the inner ring 3 to be fixed to the hub 2b is 20 to 60 mm, is also a length dimension L _3. 15 to In the case of about 40mm, the material of the hub 2b is
The present invention relates to a case where the carbon content is carbon steel having a carbon content of 0.45 to 1.10% by weight and the material of the inner ring 3 is a high carbon chromium bearing steel such as SUJ2. First, the caulking section 1
9 thickness t ₂₀ of the tip portion of at the cylindrical portion 20 prior to processing in the range of 1.5~5mm is preferred. Further, the thickness T ₂₀ of the base end portion of the cylindrical portion 20 in the range of 5~10mm is preferred. The thickness t of these tip and base ends
If restriction ₂₀ and T ₂₀ in the range, damage such as cracks is prevented from being generated in the crimped portion 19, and can be ensured support rigidity of the inner ring 3 by caulking portion 19. That is,
The distal end of the cylindrical portion 20 where the amount of deformation is large is made thinner, and the distal end can be easily plastically deformed, thereby effectively preventing the damage. Further, the inner ring 3 is connected to the step surface 1.
The thickness of the base end of the cylindrical portion 20, which is used to hold the inner ring 3, can be sufficiently secured to support the inner ring 3.

The length L ₂₀ of the cylindrical portion ₂₀ is 8
Preferably, it is about 20 mm. This length L ₂₀ is too small (L ₂₀ <8mm), damage such as cracks in a portion of the crimped portion 19 is likely to occur can not be fully form the crimped portion 19, or at the time of formation. In contrast, the length L ₂₀ is too large and (L _20> 20mm), too long length of the hollow portion that exists at the inner end of the hub 2b, the strength of the hub 2b is low Therefore, the inner end of the hub 2b is easily deformed based on the radial load applied to the inner ring 3. In addition, the cylindrical part 2 restricted to the dimensions as described above.
The work of plastically deforming 0 to form the caulking portion 19 is preferably performed by forging or swing press.

A line of action of a load applied from the plurality of rolling elements 5 to the inner ring 3 (a chain line α in FIG. 2 representing the contact angle of the rolling elements 5)
) Passes through the fitting surface between the inner peripheral surface of the inner ring 3 and the step portion 8 and does not pass through the caulking portion 19. The reason for such restriction is to prevent the above-mentioned load from acting as a force for directly deforming the caulking portion 19 inward in the diameter direction, thereby preventing the caulking portion 19 from being deformed or damaged.

Next, among the inner race 3, the cross-sectional area of the second cross-sectional area S ₃ of the outboard portion (A-A line portion in FIG. 3) than the inner ring raceway 9, in the hub 2b in the portion _Regarding the relationship with S _2b , S ₃ <S _2b, and more preferably S ₃ ≦
And 0.94S _2b. The reason why the cross-sectional areas of these parts are regulated in this way is to secure the supporting strength of the inner ring 3 with respect to the hub 2b. That is, in a state where the inner ring 3 is sandwiched between the caulking portion 19 and the step surface 12, the force (axial force) for pressing the inner ring 3 in the axial direction to prevent the rotation of the inner ring 3 is as described above. It is determined by the difference in the amount of distortion between the hub 2b and the inner ring 3 in the axial direction. That is, during caulking, the inner ring 3
Is larger than the elastic deformation of the hub 2b. After the caulking is completed, the inner ring 3 and the hub 2b
Is elastically restored, and an axial force (axial force) is applied to the inner ring 3. Since the material forming the inner race 3 and the material forming the hub 2b have substantially the same elastic modulus, as described above, S
₃ <S _2b , the amount of elastic deformation during caulking is
The inner ring 3 is larger than b. Therefore, if the cross-sectional area of each part is regulated in this manner, a sufficient compressive load is continuously applied to the inner ring 3, and the inner ring 3 rotates with respect to the hub 2b.
The generation of so-called creep can be effectively prevented.

Next, when the plurality of rolling elements 5 arranged around the inner ring 3 are balls, the distance L _O3 from the center O of the rolling element 5 to the inner end face of the inner ring 3 is determined by the diameter of the rolling element 5. it is preferably 0.75 times or more of _{D 5 (L O3 ≧ 0.75D 5} ). The reason for securing this distance L _O3 to a certain degree or more is that the diameter of the portion of the second inner raceway 9 where the rolling surface of the rolling element 5 comes into contact with the formation of the caulking portion 19 increases. This is to prevent the precision (roundness, cross-sectional shape) from deteriorating. That is, if the distance L ₀₃ is too small, the base end of the caulking portion 19 will not move to the second inner raceway 9.
Of the caulking portion 19
With the formation work, there is a possibility that the diameter of the portion of the second inner raceway 9 becomes too large to be ignored or the accuracy is deteriorated.

Next, the outer diameter R of the caulking portion 19 described above is obtained.
Reference numeral ₁₉ is preferably regulated to the following range based on the relationship between the inner diameter r ₃ of the inner ring 3 and the outer diameter R _{3 of} a portion of the outer end of the inner ring 3 deviating from the second inner ring raceway 9. r ₃ +0.7 (R ₃ −r ₃ ) ≦ R ₁₉ ≦ r ₃ +1.3 (R
_3- r ₃ ) By limiting the outer diameter R ₁₉ of the caulked portion 19 to this range, it is possible to prevent the caulked portion 19 from being damaged such as a crack, and to prevent the inner ring 3 from being attached to the hub 2b. Support strength can be secured. When the outer diameter R ₁₉ is shifted to the larger direction than the above range, it tends the damage occurred. Conversely, the outer diameter R ₁₉ is deviated in the direction small than the above range, possible to ensure the support strength is difficult.

Further, the cross-sectional shape of the curved surface portion 26 is preferably regulated as follows. First, the inclined surface portion to the start point toward the curved surface portion 26 is provided, the angle theta ₂₆ of the inclined surface portion is inclined with respect to the central axis of the inner ring 3, and 10 to 45 degrees. Further, the curvature radius r ₂₆ of the portion to be continuous with the inner peripheral surface and the inclined surface portion of the inner ring 3, and 2 to 8 mm. Further, the radius of curvature R ₂₆ of the portion to be continuous with the inclined surface portion and the end face of the inner ring 3, and 3 to 10 mm. By regulating the cross-sectional shape of the curved surface portion 26 in this way, when the cylindrical portion 20 is plastically deformed to form the caulked portion 19, an excessive stress is generated at the base end portion of the caulked portion 19. This prevents the base end from being damaged.

The operation of forming the caulking portion 19 by plastically deforming (caulking) the cylindrical portion 20 is shown in FIG.
It is preferable to use an oscillating press device 43 as shown in FIGS. The swing press device 43 includes a pressing die 22,
A holding jig 44 and a holder 45 are provided. The holder 45 is made of a metal material having sufficiently large rigidity and has a cylindrical shape with a bottom.
Has an outer end portion which can be abutted without rattling. The holding jig 44 has a ring shape as a whole by combining jig elements 47, 47 each having a semicircular shape, and has a cylindrical holding portion 48 at an inner peripheral edge. . The outer peripheral edges of the jig elements 47 and 47 and the inner peripheral surface of the upper end opening of the holder 45 are tapered surfaces that are inclined in such a direction that the diameter increases as going upward. The jig elements 47, 47 are inserted into the through holes 49, 49.
In the process of being fixedly connected to the mounting portion 51 provided on the upper inner peripheral surface of the holder 45 by bolts (not shown) through which the jig elements 47, 47 Displaces inward. Then, the inner peripheral surface of the retaining portion 48 of the retaining jig 44 constituted by each of the jig elements 47 is strongly pressed against the outer peripheral surface of the inner ring 3. With such a configuration, the holding jig 44 can sufficiently hold down the inner ring 3 even if the outer diameter of the inner ring 3 is shifted within a dimensional tolerance (50 μm).

When the cylindrical portion 20 is swaged to form the swaged portion 19, the pressing die 22 is swung and rotated while pressing the hub 2b upward through the holder 45. That is, in a state where the center axis of the pressing die 22 and the center axis of the hub 2b are inclined by the angle θ,
Is rotated about the center axis of the hub 2b. When the caulking portion 19 is formed by such a swing press, a part of the pressing die 22 in the circumferential direction is fixed to the cylindrical portion 20.
, And the working operation on the caulking portion 19 proceeds partially and continuously in the circumferential direction. Therefore, the load applied to the cylindrical portion 20 at the time of working can be reduced as compared with the case where the caulked portion 19 is formed by general forging. The pressing jig 44 prevents the hub 2b from swaying when the caulking portion 19 is processed by the pressing die 22, and deteriorates the dimensions and the shape accuracy of each component such as each raceway surface and the rolling elements 5, 5 and the like. To prevent

The tilt angle (swing angle) of the pressing die 22
θ, swing rotation speed, pressing load, etc.
9 is designed and determined in accordance with the size of the rolling bearing unit for supporting a wheel to be machined. For example, the rolling for supporting a wheel for a general passenger car having the cylindrical portion 20 having the shape and dimensions as described above. In the case of a bearing unit, it is set in the following range. First, the inclination angle θ is preferably about 0.5 to 5.0 degrees. When the inclination angle θ is less than 0.5 degree, the cylindrical portion 20 is plastically deformed to form the caulking portion 19.
, The dimensional accuracy and shape accuracy of each raceway surface and rolling elements are deteriorated, and indentations and the like are liable to occur. Conversely, if the inclination angle θ exceeds 5 degrees,
When the cylindrical portion 20 is plastically deformed into the caulking portion 19, the hub 2b is swung in the diametric direction, and the hub 2b cannot be sufficiently held by the holding jig 44. The dimensional accuracy and shape accuracy of the moving body are deteriorated, and indentations and the like are easily generated.

The swing rotation speed is 100 to 5
It is preferably about 00 r.pm (min ^-1 ). If the swing rotation speed is less than 100 rpm, the processing time is unnecessarily long. On the other hand, when the rotation speed exceeds 500 rpm, the obtained caulked portion 19 is hardened by work hardening, so that damages such as cracks are easily generated. Further, regarding the above pressing load,
About 15 to 50 t is preferable. This pressing load is 15
If it is less than t, the cylindrical portion 20 cannot be sufficiently plastically deformed, and a good caulked portion 19 cannot be obtained.
The coupling strength of the inner ring 3 to the hub 2b is insufficient. On the other hand, when the pressing load exceeds 50 t, the dimensional accuracy and shape accuracy of each raceway surface and rolling elements are deteriorated, and dents and the like are easily generated. The operation by forming the caulking portion 19 by the swing press device 43 as described above.
The effect can be obtained irrespective of the type of the metal material forming the hub 2b and the inner ring 3.

Next, FIG. 7 shows a second example of the embodiment of the present invention, which also corresponds to claims 1 to 4. In this embodiment, the present invention is applied to a wheel supporting rolling bearing unit provided with a rotation speed detecting device for detecting a rotation speed of a wheel. For this reason, in the case of this example, the diameter of the shoulder of the inner ring 3 is smaller than that of the shoulder 30 of the inner ring 3.
A step portion 31 is formed which projects more inwardly than that. The base end (left end in FIG. 7) of the tone wheel 32 constituting the rotation speed detecting device is externally fitted and fixed to the shoulder 30. A part of the tone wheel 32 is
The inner end surface of the step 31 abuts on the periphery of the base end (the left end in FIG. 7) of the step 31 to achieve positioning in the axial direction (the left-right direction in FIG. 7). A cover 33 made of synthetic resin or metal is fitted and fixed to the inner end opening of the outer ring 4, and a sensor 34 embedded in the cover 33 is opposed to the tone wheel 32 to detect the rotational speed. Make up the device.

In this embodiment, the step 31 is formed at the inner end of the inner race 3 as described above, and the step 31 is suppressed by the caulking section 19 formed at the inner end of the hub 2b. The axial distance between the caulked portion 19 and the second inner raceway 9 formed on the outer peripheral surface of the inner race 3 is increased by the formation of such a stepped portion 31. As a result, the dimensional change of the second inner raceway 9 due to the formation of the caulking portion 19 can be further reduced. Further, it is possible to prevent not only the second inner raceway 9 portion but also the outer diameter of the shoulder portion 30 from increasing.
Therefore, when the seal ring or the tone wheel is externally fitted to the shoulder portion 30 or the seal lip is slid on the outer peripheral surface of the shoulder portion 30, the function of the seal ring or the tone wheel is prevented from being impaired. it can. Also in the case of the present example, when the plurality of rolling elements 5 arranged around the inner ring 3 are balls, the second inner ring member 3 is moved from the center O of the rolling elements 5.
The distance to the inner end surface of the L _O3 is 0 diameter D ₅ of the rolling elements 5.
It is preferable that the ratio be 75 times or more (L _O3 ≧ 0.75D ₅ ). Since the configuration and operation of the other parts are the same as those in the first example described above, the same parts are denoted by the same reference numerals, and redundant description will be omitted. In the case of this example (and in the case of the following third to eleventh examples), the hardened and hardened portion of the hub is indicated by an oblique lattice.

Next, FIG. 8 shows a third example of the embodiment of the present invention, which also corresponds to claims 1 to 4. In each of the first example and the second example described above, the hub 2b is rotatably provided inside the outer ring 4 that does not rotate, whereas in the case of this example, the side of the outer ring 4 rotates. I am doing it. That is, in the case of this example, the outer wheel 4 rotates together with the wheel. Since the rotating side and the stationary side are reversed in the inside and outside in the diametric direction, and the inside and outside in the axial direction are accordingly partially reversed, because the configuration and operation are the same as in the case of the above-described first example, The same parts are denoted by the same reference numerals, and duplicate description will be omitted.

Next, FIG. 9 shows a fourth embodiment of the present invention, which also corresponds to claims 1 to 4. In each of the first and second examples and the third example described above, wheel supporting rolling for rotatably supporting driven wheels that are not rotationally driven (front wheels of FR and RR vehicles, rear wheels of FF vehicles). While the present invention has been applied to the bearing unit, in the case of this example, the drive wheels (the rear wheels of the FR and RR vehicles, the front wheels of the FF vehicles, and all the wheels of the 4WD vehicles) are rotatably supported. The present invention is applied to a rolling bearing unit for supporting a wheel.

For this reason, in the case of the present embodiment, the hub 2c is formed in a cylindrical shape, and the female spline portion 35 is formed on the inner peripheral surface of the hub 2c. A drive shaft 37 having a male spline portion formed on the outer peripheral surface thereof is inserted into the female spline portion 35 and attached to the constant velocity joint 36. On the other hand, the inner ring 3 is externally fitted to a step 8 formed on the outer peripheral surface of the inner end of the hub 2c, and a step 38 is formed at a portion of the inner ring 3 near the inner diameter of the inner end surface. The caulking portion 19 formed at the inner end of the hub 2c is caulked toward the step portion 38. In this state, the caulking portion 19 does not protrude inward from the inner end surface of the inner ring 3. Therefore, the outer end surface of the main body portion 39 of the constant velocity joint 36 is in contact with the inner end surface of the inner ring 3. In this manner, with the outer end surface of the main body portion 39 abutting on the inner end surface of the inner race 3, the nut 40 is screwed into a portion protruding from the outer end surface of the hub 2c at the tip end of the drive shaft 37. By further tightening, the inner ring 3 and the hub 2c are strongly clamped in the axial direction.

In the structure of this embodiment, when the plurality of rolling elements 5 arranged around the inner ring 3 are balls, preferably, the distance from the center O of the rolling elements 5 to the step surface of the step 38 is preferable. L
_{38 is set} to 0.75 times or more (L ₃₈ ≧ 0.75D ₅ ) of the diameter D ₅ of the rolling element 5 (see FIG. 3). Since the configuration and operation of the other parts are the same as in the case of the first example described above,
The same parts are denoted by the same reference numerals, and duplicate description will be omitted.

In this embodiment, since the hub 2c has a hollow cylindrical shape, it may be difficult to make the cross-sectional area of the hub 2c larger than that of the inner race 3. . However, in the structure of the present embodiment, the inner ring 3 is connected to the hub 2 by an axial force based on the tightening of the nut 38 in a use state.
Since the pressing force is strongly applied to the step surface 12c, the force acting on the caulking portion 19 from the inner ring 3 in the direction of loosening the caulking portion 19 is limited. Therefore, even if the relationship of the cross-sectional area cannot be satisfied, the durability of the caulked portion 19 is not impaired.

Next, FIG. 10 shows a fifth example of the embodiment of the present invention, which also corresponds to claims 1 to 4. In the case of this example, the swaged portion 1 formed at the inner end of the hub 2c
The inner ring 3 is swaged toward the inner end face of the inner ring 3, and the swaged portion 19 a protrudes inward in the axial direction from the inner end face of the inner ring 3. An annular flat surface 42 is formed on the inner surface of the caulking portion 19a, and the flat surface 42 and the outer end surface of the main body 39 of the constant velocity joint 36 are in contact with each other. The caulked portion 19a is made of raw carbon steel. However, since the flat surface 42 abuts on the outer end surface of the main body portion 39 over a large area, the surface pressure applied to the abutting portion even when the nut 40 is tightened. Is never extremely high. Therefore,
Regardless of use for a long period of time, the caulking portion 19a is prevented from sagging, and by the caulking portion 19a,
It is possible to effectively prevent loosening of the nut 40 and rattling of the rolling elements 5 and 5 installation portions. The configuration and operation of the other parts are the same as in the case of the above-described fourth example, and therefore, the same reference numerals are given to the same parts, and redundant description will be omitted.

Next, FIG. 11 to FIG.
14 shows sixth to eighth examples of the embodiment of the present invention corresponding to FIG. In the case of the first to fifth examples described above, the hardened hardened layer applied to the member forming the caulking portion 19 was continuously formed, whereas in the case of the fifth to seventh examples, the hardened layer was hardened. The filling hardened layer is formed discontinuously for each particularly required portion. That is, in the case of the sixth example shown in FIG. 11, only the first inner raceway 7 and the step surface 12 and the corner R existing near the inner periphery of the step surface 12 are shown in FIG. In the case of the seventh example, only the first inner ring raceway 7 and the stepped surface 12 and the outer peripheral surface of the corner R and the base half of the step 8 are shown in FIG.
In the case of the eighth example shown in FIG. 3, the first inner ring raceway 7 portion, the base end portion of the first flange 6, the step surface 12, and the corner R
The quench hardened layer is formed only on the outer peripheral surface of the base portion and the base half of the step portion 8. However, as described above, the quenched and hardened layer is not formed discontinuously at each of the particularly required portions as described above, but rather than the first to fifth examples shown in FIGS. 1, 7, 8, 9, and 10. As described above, when the adjacent hardened hardened layers are continuously formed, the strength and durability of the member to which the hardened hardened layer is applied can be improved. The configuration and operation of the other parts are the same as in the case of the first example described above.

Next, FIG. 14 shows a ninth embodiment of the present invention corresponding to claim 5. The rolling bearing unit for supporting wheels of the present example includes first and second inner raceways 7,
9 are formed on the outer peripheral surfaces of the first and second inner rings 41 and 3 which are fitted to the step 8a of the hub 2d. The first and second inner rings 41 and 3 are both made of high carbon steel such as high carbon chromium bearing steel such as SUJ2, and are hardened and hardened to the core. Also, these first and second inner rings 41,
Numeral 3 is sandwiched between a caulked portion 19 formed at the inner end of the hub 2d and a stepped surface 12 formed at the base of the first flange 6 in a state of being fitted to the step 8a.

In this embodiment, the hub 2d can be made of carbon steel having a carbon content of less than 0.45% by weight. 14, that is, the base end of the first flange 6, the base end of the step 8a including the stepped surface 12, and the outer peripheral surface of the step 8a. A portion other than the edge portion is hardened to increase the hardness of the portion. However, at least the cylindrical portion 20 of the hub 2d which forms the caulking portion 19
Is left raw without being subjected to the above quenching treatment. The reason for performing the quenching process on each portion of the hub 2d and the reason for restricting the axial position (point A in FIG. 14) of the inner end of the quenched hardened layer indicated by the oblique lattice are described above. This is similar to the case of one example.

In the case of the rolling bearing unit for supporting a wheel of the present embodiment configured as described above, since the inner raceway is not provided on the hub 2d itself, the caulking portion 19 is used as the material of the hub 2d.
Can be used, and a carbon steel having a carbon content of less than 0.45% by weight can be used. However, the hub 2d is the same as that shown in FIG.
A quenched and hardened layer is formed in the area indicated by the oblique lattice. For this reason, fretting wear is prevented from occurring in the portion where the hardened hardened layer is formed, or the portion where the hardened hardened layer is formed is prevented from being deformed, thereby ensuring the strength and durability of the hub 2d. it can. On the other hand, since at least the cylindrical portion 20 provided on the hub 2d is left as it is without being subjected to the quenching process, a caulking portion for connecting the hub 2d and the first and second inner rings 41, 3 is provided. There is no trouble in processing the 19 and no damage to the caulked portion 19.

Further, the second inner race 3 fitted to the step 8a
Is made of high-carbon steel such as bearing steel and hardened to the core. For this reason, similarly to the case of the inner ring 3 of the first example described above, even when a large load is applied to the second inner ring 3 due to the processing of the caulking portion 19 formed on the hub 2d,
The deformation of the second inner ring 3 can be prevented, and the internal clearance of the rolling bearing unit can be prevented from deviating from a desired value.
Further, it is possible to prevent the diameter of the second inner raceway 9 formed on the outer peripheral surface of the second inner raceway 3 from changing or to reduce the accuracy, and to reduce the rolling fatigue life of the second inner raceway 9. Prevention. In the case of this example, the hub 2d may be made of carbon steel having a carbon content of 0.45 to 1.10% by weight. In this case, the strength and durability of the hub 2d are further improved. The configuration and operation of the other parts are the same as in the case of the first example described above.

Note that this example (and 10th to 11th to be described later)
In the case of Example), the content of carbon in the carbon steel constituting the hub 2d is restricted to a range of 0.20 to 1.10% by weight, and at least the hardness of the cylindrical portion 20 is set to Hv before caulking.
200 to 300. The hub 2d is manufactured by forging a carbon steel satisfying such conditions. The carbon content in the carbon steel constituting the hub 2d is 0.2%.
When the content is in the range of 0 to 0.60% by weight, at least the cylindrical portion 20 is not subjected to an annealing treatment after forging and before the cylindrical portion 20 is swaged and spread. On the other hand, when the content of carbon in the carbon steel constituting the hub 2d is in the range of 0.60 to 1.10% by weight, after forging, before the cylindrical portion 20 is swaged and expanded. Here, at least the cylindrical portion 20 is subjected to an annealing treatment. The hardness of the hub 2d and the necessity of annealing after forging are the same as in the case of the first example.

15 and 16 show tenth to eleventh embodiments of the present invention, which also correspond to claim 5. In the case of these tenth to eleventh examples, the hardened hardened layer applied to the hub 2d is formed only on the part that receives a particularly large load when the rolling bearing is used. That is, FIG.
In the case of the tenth example shown in FIG. 5, only the base end portion of the step 8a including the stepped surface 12 is provided. In the case of the eleventh example shown in FIG. The quench hardened layer is formed only on the base end portion and the base end portion of the first flange 6, respectively. The configuration and operation of the other parts are the same as in the case of the ninth example described above.

Although not shown in the drawings, in each of the above-described embodiments, each caulking portion 19 and the inner ring (second inner ring) 3 do not necessarily have to be in close contact with each other over the entire surface of the opposing portion. Is also good. Even if a gap exists in a part of the facing portion, the operation and effect of the present invention can be similarly obtained. The hardness of the cylindrical portion 20 before the formation of the caulking portion 19 is Hv200 to 30.
In the state where the cylindrical portion 20 is swaged and expanded to form the swaged portion 19, the hardness of the swaged portion 19 becomes larger than Hv200 to 300 due to work hardening.

[0059]

The rolling bearing unit for supporting a wheel according to the present invention is constructed and operates as described above, so that a rolling bearing unit for supporting a wheel which is low in cost and has sufficient durability can be realized. Furthermore, as shown in the example in the drawing, the shape of the cylindrical portion for forming the caulked portion is reduced toward the leading edge in a state before the cylindrical portion is caulked outward in the diametrical direction. In addition, it is possible to prevent the occurrence of damage such as cracks, and to prevent the diameter of the inner race fixed to the hub by the caulked portion from changing so as to be a practical problem. The possibility of damage to the inner ring due to the fixing operation can be reduced, the preload can be maintained at an appropriate value, and the cost can be reduced by reducing the number of parts, component processing, and assembly man-hours.

[Brief description of the drawings]

FIG. 1 is a half sectional view showing a first example of an embodiment of the present invention.

FIG. 2 is a partially enlarged cross-sectional view showing a state in which an inner end portion of a hub is swaged to fix an inner ring at the time of manufacturing the structure of the first example.

FIG. 3 is a partially enlarged sectional view showing a state before the inner end portion of the hub is swaged.

FIG. 4 is a sectional view taken along line AA of FIG. 3;

FIG. 5 is a longitudinal sectional view of a main part of the swing press device.

FIG. 6 is a plan view of a holding jig incorporated in the swing press device.

FIG. 7 is a half sectional view showing a second example of the embodiment of the present invention.

FIG. 8 is a half sectional view showing the third example.

FIG. 9 is a half sectional view showing the fourth example.

FIG. 10 is a half sectional view showing the fifth example.

FIG. 11 is a half sectional view showing the sixth example.

FIG. 12 is a half sectional view showing the seventh example.

FIG. 13 is a half sectional view showing the eighth example.

FIG. 14 is a half sectional view showing the ninth example.

FIG. 15 is a half sectional view showing the tenth example.

FIG. 16 is a half sectional view showing the eleventh example.

FIG. 17 is a half sectional view showing a first example of a conventional structure.

FIG. 18 is a sectional view showing the second example.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a Wheel support hub unit 2, 2a, 2b, 2c, 2d Hub 3 Inner ring (2nd inner ring) 4 Outer ring 5 Rolling element 6 First flange 7 First inner ring track 8, 8a Step 9 Second Inner ring raceway 10 Male screw part 11 Nut 12, 12a Stepped surface 13 Second inner ring member 14 Locking concave part 15 First outer ring raceway 16 Second outer ring raceway 17 Second flange 18 Hub 19, 19a Caulking part 20 Cylindrical part DESCRIPTION OF SYMBOLS 21 Taper hole 22 Press type 23 Convex part 24 Concave part 25 Gap 26 Curved surface part 27 Space 28 Seal ring 29 Lid 30 Shoulder part 31 Step part 32 Tone wheel 33 Cover 34 Sensor 35 Female spline part 36 Constant velocity joint 37 Drive shaft 38 Step part 39 Body part 40 Nut 41 First inner ring 42 Flat surface 43 Swing press device 44 Holding jig 45 Holder 46 Bottom part 7 jig elements 48 pressing section 49 through hole 50 mounting portion

Continuation of front page (72) Inventor Hiroyuki Sawai 1-5-50 Kumeinuma Shinmei, Fujisawa-shi, Kanagawa Nippon Seiko Co., Ltd.

Claims (6)

[Claims] 1. A hub formed with a first flange on one end outer peripheral surface, a first inner raceway on an intermediate outer peripheral surface, and the first inner race formed on the other end of the hub. A step portion having an outer diameter smaller than that of the portion where the track is formed, an inner ring formed with a second inner ring track on the outer peripheral surface and fitted to the step portion, and the first inner ring track on the inner peripheral surface A first outer raceway facing the second outer raceway facing the second inner raceway, an outer race formed with a second flange on the outer peripheral surface, and the first and second inner raceways, respectively. A plurality of rolling elements respectively provided between the first and second outer raceways, and formed at a portion protruding from an inner race fitted at least to the step at the other end of the hub. The crimped part formed by caulking and expanding the cylindrical part outward in the diameter direction In the rolling bearing unit for supporting a wheel in which the inner ring is pressed down toward the step surface of the step and the inner ring externally fitted to the step is fixedly connected to the hub, the hub has a carbon content of 0. 45% by weight or more of carbon steel, and at least the first inner ring raceway portion is hardened by quenching, and at least the cylindrical portion is left raw without being subjected to the quenching process. A rolling bearing unit for supporting wheels, made of carbon steel and hardened to the core. 2. The carbon content of carbon steel constituting the hub is 0.45 to 1.10% by weight, and the first inner raceway is formed directly on the outer peripheral surface of the intermediate portion of the hub. At least a portion of the hub where the first inner raceway is formed is hardened and hardened, and at least the cylindrical portion formed at the other end of the hub has a hardness of Hv before caulking.
The wheel bearing rolling bearing unit according to claim 1, wherein the number is 200 to 300. 3. The carbon content of carbon steel constituting the hub is 0.45 to 0.60% by weight, and the hub is made by forging this carbon steel. 3. The rolling bearing unit for a wheel according to claim 1, wherein the hub is not annealed after forging of the hub. 4. 4. The carbon content of carbon steel constituting the hub is 0.60 to 1.10% by weight, and the hub is made by forging this carbon steel. 3. The rolling bearing unit for a wheel according to claim 1, wherein the hub is annealed after forging of the hub. 5. A hub having a first flange formed on an outer peripheral surface at one end, a step formed from an intermediate portion in the axial direction to the other end on an outer peripheral surface of the hub, and a first inner ring formed on an outer peripheral surface. A first inner ring that forms a raceway and is externally fitted to one end of the step, and a second inner race that forms a second inner raceway on the outer peripheral surface and is externally fitted to the other end of the step, A first outer raceway facing the first inner raceway on the inner peripheral surface and a second outer raceway facing the second inner raceway on the second outer raceway, and an outer race formed with a second flange, respectively, A plurality of rolling elements are provided between the first and second inner raceways and the first and second outer raceways, respectively. A caulking part formed by caulking and expanding the cylindrical part formed at the part protruding from the second inner ring fitted on the end side outward in the diameter direction Thereby, the first externally fitted to the step portion,
In a wheel supporting rolling bearing unit in which a second inner ring is pressed toward a step surface of the step portion and first and second inner rings fitted to the step portion are fixed to the hub, Is hardened by quenching at least one end portion of the step portion including the step surface of the step portion, and at least the cylindrical portion is left as it is without being subjected to the quenching process, the first and second portions A rolling bearing unit for wheel support, characterized in that the inner rings are each made of high carbon steel and hardened to the core. 6. A hub formed with a first flange on one end outer peripheral surface, a first inner raceway on an intermediate outer peripheral surface, and the first inner race formed on the other end of the hub. A step portion having an outer diameter smaller than that of the portion where the track is formed, an inner ring formed with a second inner ring track on the outer peripheral surface and fitted to the step portion, and the first inner ring track on the inner peripheral surface A first outer raceway facing the second outer raceway facing the second inner raceway, an outer race formed with a second flange on the outer peripheral surface, and the first and second inner raceways, respectively. A plurality of rolling elements respectively provided between the first and second outer raceways, and formed at a portion protruding from an inner race fitted at least to the step at the other end of the hub. The crimped part formed by caulking and expanding the cylindrical part outward in the diameter direction The inner ring is pressed down toward the step surface of this step, and in the wheel supporting rolling bearing unit in which the inner ring fitted to this step is fixedly connected to the hub, the cylindrical portion is swaged radially outward. The work is performed by a rocking press, and a rolling bearing unit for supporting a wheel in which the inner ring having a second inner raceway formed on the outer peripheral surface or the second inner ring is held down by a jig during the caulking operation.