Metal working – Method of mechanical manufacture – Wheel making
Reexamination Certificate
2000-12-20
2003-04-29
Vidovich, Gregory M. (Department: 3726)
Metal working
Method of mechanical manufacture
Wheel making
C029S894361, C029S898070, C029S898062, C029S509000, C301S105100, C384S544000
Reexamination Certificate
active
06553666
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a wheel-support rolling bearing unit, which is used for rotatably supporting vehicle wheels on suspension devices, and also relates to a method of manufacturing the same.
The vehicle wheels are supported on the suspension devices by the wheel-support rolling bearing unit.
FIG. 4
shows a conventional wheel-support rolling bearing unit widely used. The conventional wheel-support rolling bearing unit
1
includes a hub
2
, an inner ring
3
, an outer ring
4
, and a plurality of rolling elements
5
. A first flange
6
for supporting the wheel is formed at the outer end of the outer peripheral surface of the hub
2
(the word “outer side or outside” means the outer side of the vehicle body as viewed in the widthwise direction in a state that the unit is assembled into the motor vehicle, and the left side in those figures except FIG.
8
. The word “inner side or inside” means locations closer to the center of the vehicle body as viewed in the widthwise direction, and the right side in those figures except FIG.
8
.). A first inner raceway
7
is formed in the outer surface of a middle portion of the hub
2
. A stepped part
8
having the reduced outside diameter is formed at the inner end thereof.
The inner ring
3
having a second inner raceway
9
formed therein is fit to the stepped part
8
. A male threaded portion
10
is formed in the inner end of the hub
2
. The top end (the right end in
FIG. 4
) of the male threaded portion
10
is extended inward beyond the inner end face of the inner ring
3
. The inner ring
3
is held between the nut
11
screwed to the male threaded portion
10
and a step surface
12
of the stepped part
8
, whereby the inner ring
3
is firmly coupled to a predetermined position on the hub
2
. An engaging recess
13
is formed in the outer peripheral surface of the top end of the male threaded portion
10
. The nut
11
is fastened by a predetermined torque, and then a part of the nut
11
, which is aligned with the engaging recess
13
, is radially and inwardly caulked, thereby preventing the loosening of the nut
11
.
A first outer raceway
14
and a second outer raceway
15
are formed in the inner peripheral surface of the outer ring
4
. The first outer raceway
15
is confronted with the first inner raceway
7
. The second outer raceway
15
is confronted with a second inner raceway
9
. A plurality of rolling elements
5
are located between the first inner raceway
7
and the first outer raceway
14
. A plurality of rolling elements
5
are located between the second inner raceway
9
and the second outer raceway
15
. In the illustrated instance, the rolling elements
5
are balls; however, in the case of the wheel-support rolling bearing unit for motor vehicles which is heavy, those may be tapered rollers.
To assemble the wheel-support rolling bearing unit
1
into the motor vehicle, the outer ring
4
is fixed to a suspension device with a second flange
16
formed on the outer peripheral surface of the outer ring
4
, and the wheel is fixed to the first flange
6
. As a result, the wheel is rotatably supported on the suspension device.
In Japanese Patent Unexamined Publication No. Hei.11-129703, there is described a wheel-support rolling bearing unit
1
a
as shown in
FIGS. 5
to
7
. The wheel-support rolling bearing unit
1
a
as a second conventional technique includes a hub
2
a
, an inner ring
3
, an outer ring
4
, and a plurality of rolling elements
5
. A first flange
6
for supporting the wheel is formed at a portion of the hub
2
a
which is closer to the outer end of the outer peripheral surface thereof. A first inner raceway
7
is formed in the outer surf ace of a middle portion of the hub
2
a
. A stepped part
8
having the reduced outside diameter is formed at the inner end thereof.
A cylindrical portion
18
, which is used for forming a caulking portion
17
to fix the inner ring
3
, is formed in the inner end of the hub
2
a
. A thickness of the cylindrical portion
18
becomes small toward its top end (the right end in
FIG. 7
) before the cylindrical portion
18
shown in
FIG. 7
is expanded, for caulking, outward in the diameter directions. Accordingly, a tapered hole
19
is formed in the inner end face of the hub
2
a
. The inside diameter of the tapered hole becomes small toward a recess.
To expand, for caulking, the top end of the cylindrical portion
18
in order to fasten the inner ring
3
to the inner end of the hub
2
a
, a force piston
20
is forcibly pressed against the top end of the cylindrical portion
18
in a state that the hub
2
a
is fixed so as not to shift in the axial direction, as shown in FIG.
6
. An outward curved portion
21
, shaped like a truncated cone, which may be thrust into the cylindrical portion
18
, is formed in the central portion of the end surface (left end surface in
FIG. 6
) of the force piston
20
. An inward curved portion or recess
22
is formed surrounding the outward curved portion
21
. A cross section of the recess
22
is configured to have a complex curved surface whose radius of curvature becomes small toward the outside so that a cross section of the caulking portion
17
, which is formed by plastically forming the top end of the cylindrical portion
18
by the recess
22
, gradually reduces in size from the base end to the top end, and abruptly reduces at the top end.
By pressing the force piston
20
having the outward curved portion
13
and the recess
22
, which are shaped and have dimensions as mentioned above, against the top end of the cylindrical portion
18
, the top end of the cylindrical portion
18
is forcibly expanded outward in the diameter directions for caulking, to thereby form a caulking portion
17
. The inner ring
3
is firmly held between the caulking portion
17
and a step surface
12
of the stepped part
8
formed at the inner end of the hub
2
a
, whereby the inner ring
3
is fastened to the hub
2
a.
For a work to form the caulking portion
17
by plastically deforming (expanding for caulking) the cylindrical portion
18
, it is preferable to use a swing press
23
as shown in FIG.
8
. The swing press
23
is made up of a force piston
20
, a holding tool
24
and a holder
25
. In forming the caulking portion
17
by expanding for caulking the cylindrical portion
18
, the force piston
20
is displaced in a swing manner while pushing upward the hub
2
a
with the aid of the holder
25
. In a state that the center axes of the force piston
20
and the hub
2
a
are inclined at an angle &thgr; with respect to each other, the force piston
20
is turned about the center axis of the hub
2
a
, while being in contact with each other. In forming the caulking portion
17
by the swing press as just-mentioned, a part of the circumference of the force piston
20
is pressed against the cylindrical portion
18
, so that the caulking expanding work of the caulking portion
17
continuously progresses in part in the circumferential direction. For this reason, when comparing with the forming of the caulking portion
17
by ordinary forging process, a load acting on the cylindrical portion
18
may be reduced during the forging process. The holding tool
24
prevents the inner ring
3
and the hub
2
a
from moving in the radial direction during the caulking expanding work of the caulking portion
17
by the force piston
20
.
In the conventional wheel-support rolling bearing unit thus constructed, it is difficult to apply a pre-load to the rolling elements
5
and to render normal a fitting state of the inner ring
3
to the hub
2
a
. In recent years, a measure in which the pre-load is applied to the rolling elements
5
has been employed in order to increase a rigidity of the wheel-support rolling bearing unit. The related component parts are dimensioned so that the pre-loading has an appropriate value in a state that the outer end face
28
of the inner ring
3
is in contact with the step surface
12
formed on the outer peripheral surface of the hub
2
a.
In a
Compton Eric
NSK Ltd.
Sughrue & Mion, PLLC
Vidovich Gregory M.
LandOfFree
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