U.S. patent application number 13/204948 was filed with the patent office on 2012-03-01 for manufacturing method for vehicle hub unit.
This patent application is currently assigned to JTEKT CORPORATION. Invention is credited to Hiroyuki OUMI, Kentaro SHIRAKAMI.
Application Number | 20120047740 13/204948 |
Document ID | / |
Family ID | 44508981 |
Filed Date | 2012-03-01 |
United States Patent
Application |
20120047740 |
Kind Code |
A1 |
SHIRAKAMI; Kentaro ; et
al. |
March 1, 2012 |
MANUFACTURING METHOD FOR VEHICLE HUB UNIT
Abstract
There is provided a manufacturing method for a vehicle hub unit
in which a hub wheel is arranged radially inward of an outer ring
via rolling elements, an inner ring member is fixed to an end
portion of a hub spindle of the hub wheel by clinching, a spline
tooth portion that meshes with a tooth portion of a constant
velocity joint that transmits driving force to the hub unit is
formed at a clinched portion of the hub spindle, and a protruding
portion is formed at a radially inner side portion of a bottom of
the spline tooth portion. The clinched portion is formed by
plastically deforming a cylindrical end portion of the hub spindle
outward with a clinching tool. The clinching tool includes a punch
and an oscillating spindle to which the punch is non-rotatably
attached.
Inventors: |
SHIRAKAMI; Kentaro;
(Osaka-shi, JP) ; OUMI; Hiroyuki; (Yao-shi,
JP) |
Assignee: |
JTEKT CORPORATION
Osaka
JP
|
Family ID: |
44508981 |
Appl. No.: |
13/204948 |
Filed: |
August 8, 2011 |
Current U.S.
Class: |
29/894.36 |
Current CPC
Class: |
B21J 9/025 20130101;
B21K 25/00 20130101; F16C 2326/02 20130101; B60B 27/0036 20130101;
F16D 1/076 20130101; B60B 27/0005 20130101; B60B 27/0094 20130101;
F16C 33/581 20130101; B60B 2310/3142 20130101; F16C 19/186
20130101; Y10T 29/49533 20150115 |
Class at
Publication: |
29/894.36 |
International
Class: |
B21D 53/26 20060101
B21D053/26 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 30, 2010 |
JP |
2010-192413 |
Claims
1. A manufacturing method for a vehicle hub unit in which a hub
wheel is arranged radially inward of an outer ring via rolling
elements, an inner ring member is fixed to an end portion of a hub
spindle of the hub wheel by clinching, a spline tooth portion that
meshes with a tooth portion of a constant velocity joint that
transmits driving force to the hub unit is formed at a clinched
portion of the hub spindle, and a protruding portion is fowled at a
radially inner side portion of a bottom of the spline tooth
portion, wherein: the clinched portion is formed by plastically
deforming a cylindrical end portion of the hub spindle outward with
a clinching tool; the clinching tool includes a punch that is
configured to be inserted into the cylindrical end portion and that
has a guide portion that is configured to contact the cylindrical
end portion with a predetermined inclination angle with respect to
an inner peripheral surface of the end portion, and an oscillating
spindle to which the punch is non-rotatably attached; the guide
portion is formed in a projecting shape so as to project from a
center portion of one end surface of the punch; a tooth profile for
plastically machining the spline tooth portion is formed in the one
end surface of the punch, at a portion radially outward of a base
of the guide portion; and the guide portion of the punch is
inserted into the end portion of the hub spindle, the punch is
pressed against the end portion of the hub spindle with
predetermined pressing force, and a spindle that is coaxial with
the hub spindle is rotated to oscillate the clinching tool, so that
the clinched portion and the spline tooth portion are formed at the
same time through plastic deformation while plastic deformation of
the end portion of the hub spindle toward a radial center of the
hub spindle is suppressed by the guide portion.
2. The manufacturing method for a vehicle hub unit according to
claim 1, wherein a restraining member that prevents the inner ring
member from deforming radially outward during oscillating clinching
is arranged radially outward of the inner ring member so as to be
in contact with the inner ring member.
3. The manufacturing method for a vehicle hub unit according to
claim 2, wherein a seal member is arranged between an inner
peripheral surface of the outer ring and an outer peripheral
surface of the inner ring member, and the restraining member is
arranged so as to be in contact with a portion of the outer
peripheral surface of the inner ring member, at which the seal
member is arranged.
4. The manufacturing method for a vehicle hub unit according to
claim 2, wherein the restraining member is formed of an annular
member, and has a guide on an inner peripheral surface of the
restraining member, the guide protruding radially inward, and the
guide contacts an end surface of the inner ring member to determine
a position of the restraining member in an axial direction of the
restraining member.
5. The manufacturing method for a vehicle hub unit according to
claim 3, wherein the restraining member is formed of an annular
member, and has a guide on an inner peripheral surface of the
restraining member, the guide protruding radially inward, and the
guide contacts an end surface of the inner ring member to determine
a position of the restraining member in an axial direction of the
restraining member.
6. The manufacturing method for a vehicle hub unit according to
claim 1, wherein an applicator made of spongy porous material is
used to apply lubricant in advance to the end portion of the hub
spindle, the end portion being subjected to oscillating
clinching.
7. The manufacturing method for a vehicle hub unit according to
claim 2, wherein an applicator made of spongy porous material is
used to apply lubricant in advance to the end portion of the hub
spindle, the end portion being subjected to oscillating
clinching.
8. The manufacturing method for a vehicle hub unit according to
claim 3, wherein an applicator made of spongy porous material is
used to apply lubricant in advance to the end portion of the hub
spindle, the end portion being subjected to oscillating
clinching.
9. The manufacturing method for a vehicle hub unit according to
claim 4, wherein an applicator made of spongy porous material is
used to apply lubricant in advance to the end portion of the hub
spindle, the end portion being subjected to oscillating
clinching.
10. The manufacturing method for a vehicle hub unit according to
claim 5, wherein an applicator made of spongy porous material is
used to apply lubricant in advance to the end portion of the hub
spindle, the end portion being subjected to oscillating clinching.
Description
INCORPORATION BY REFERENCE
[0001] The disclosure of Japanese Patent Application No.
2010-192413 filed on Aug. 30, 2010 including the specification,
drawings and abstract, is incorporated herein by reference in its
entirety.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention relates to a manufacturing method for a
vehicle hub unit in which a member that constitutes an inner ring
is fixed by clinching to an end portion of a hub spindle of a hub
wheel to which a wheel is fitted.
[0004] 2. Description of Related Art
[0005] A hub unit is used to support a wheel of an automobile such
that the wheel is rotatable with respect to a suspension. FIG. 7 is
a sectional view that illustrates an example of an existing hub
unit.
[0006] A hub unit 51 shown in FIG. 7 includes a hub wheel 53, an
inner ring member 54, an outer ring 55, and a plurality of rolling
elements 56. The hub wheel 53 has a hub spindle 52. The inner ring
member 54 is fixed to one end of the hub spindle 52 by clinching.
The outer ring 55 is arranged radially outward of the hub spindle
52. The rolling elements 56 are rollably arranged between one of
outer ring raceways 55a of the inner peripheral surface of the
outer ring 55, and an inner ring raceway 52a of the outer
peripheral surface of the hub spindle 52 or an inner ring raceway
54a of the outer peripheral surface of the inner ring member 54. A
flange portion 57 is formed at the end portion (left end portion in
FIG. 7) of the hub wheel 53, and a wheel of a tire, a brake disc,
and the like (not shown), are fitted to the flange portion 57. A
fixing flange 58 is formed on the outer peripheral surface of the
outer ring 55. The fixing flange 58 is used to fit the hub unit 51
to a vehicle body-side member (not shown) supported by a suspension
of a vehicle.
[0007] Rotational driving force of a drive shaft 60 is transmitted
to the hub unit 51 via a constant velocity joint 59. As one method
of transmitting the rotational driving force, there is known a
method in which, as shown in FIG. 8 in detail, a spline tooth
portion (side face spline) 62 is formed at a clinched portion 61 of
the hub spindle end portion for fixing the inner ring member 54,
and then the spline tooth portion 62 is meshed with a tooth portion
(side face spline) 64 formed at an end surface of the outer ring 63
of the constant velocity joint 59 (see, for example, Published
Japanese Translation of PCT Application No. 2008-536737 and
Japanese Patent Application Publication No. 2008-174178).
[0008] In the hub units described in Published Japanese Translation
of PCT Application No. 2008-536737 and Japanese Patent Application
Publication No. 2008-174178, rotational driving force is
transmitted to the hub unit via a constant velocity joint due to
the mesh of the teeth that extend in a direction substantially
perpendicular to a rotary shaft.
[0009] A manufacturing method for the above-described spline tooth
portion 62 will be described below with reference to FIG. 9. First,
the hub wheel 53 with the inner ring member 54 fitted around the
outer periphery of one end of the hub spindle 52 is fixed to a base
146 using knock-pins 145. Subsequently, oscillating clinching is
performed to form the spline tooth portion 62 and the clinched
portion 61 at the same time. In the oscillating clinching, a punch
142 having a tooth profile 142a for forming the spline tooth
portion 62 is pressed against a cylindrical end portion of the hub
spindle 52 and the punch 142 is oscillated. FIG. 10 is an enlarged
view of a main portion in FIG. 9.
[0010] However, an end surface of the existing punch 142 has a
conical shape of which the center just slightly protrudes.
Therefore, the material of the hub spindle end portion may be
deformed toward the radial center of the hub spindle 52 as the
oscillating clinching proceeds. If plastic deformation toward the
radial center of the hub spindle 52 becomes significant, a portion
61a formed due to deformation toward the radial center of the hub
spindle 52 may contact the constant velocity joint when the
constant velocity joint is fitted to the hub unit.
SUMMARY OF THE INVENTION
[0011] It is an object of the invention to provide a manufacturing
method for a vehicle hub unit, according to which deformation of an
end portion of a hub spindle toward the radial center of the hub
spindle during oscillating clinching is prevented to thereby make
it possible to avoid contact between the end portion and a constant
velocity joint when the constant velocity joint is fitted to the
hub unit.
[0012] An aspect of the invention relates to a manufacturing method
for a vehicle hub unit in which a hub wheel is arranged radially
inward of an outer ring via rolling elements, an inner ring member
is fixed to an end portion of a hub spindle of the hub wheel by
clinching, a spline tooth portion that meshes with a tooth portion
of a constant velocity joint that transmits driving force to the
hub unit is formed at a clinched portion of the hub spindle, and a
protruding portion is formed at a radially inner side portion of a
bottom of the spline tooth portion. The clinched portion is formed
by plastically deforming a cylindrical end portion of the hub
spindle outward with a clinching tool. The clinching tool includes
a punch that is configured to be inserted into the cylindrical end
portion and that has a guide portion that is configured to contact
the cylindrical end portion with a predetermined inclination angle
with respect to an inner peripheral surface of the end portion, and
an oscillating spindle to which the punch is non-rotatably
attached. The guide portion is formed in a projecting shape so as
to project from a center portion of one end surface of the punch. A
tooth profile for plastically machining the spline tooth portion is
formed at the one end surface of the punch, at a portion radially
outward of a base of the guide portion. The guide portion of the
punch is inserted into the end portion of the hub spindle, the
punch is pressed against the end portion of the hub spindle with
predetermined pressing force, and a spindle that is coaxial with
the hub spindle is rotated to oscillate the clinching tool, so that
the clinched portion and the spline tooth portion are formed at the
same time through plastic deformation while plastic deformation of
the end portion of the hub spindle toward a radial center of the
hub spindle is suppressed by the guide portion.
BRIEF DESCRIPTION OF THE DRAWINGS
[0013] Features, advantages, and technical and industrial
significance of exemplary embodiments of the invention will be
described below with reference to the accompanying drawings, in
which like numerals denote like elements, and wherein:
[0014] FIG. 1 is a sectional view that illustrates an example of a
vehicle hub unit manufactured by a manufacturing method according
to an embodiment of the invention;
[0015] FIG. 2 is an enlarged view that illustrates an end portion
of a clinched portion of the vehicle hub unit shown in FIG. 1;
[0016] FIG. 3 is a sectional view for explaining the manufacturing
method according to the embodiment of the invention;
[0017] FIG. 4 is an enlarged view of a main portion in FIG. 3;
[0018] FIG. 5A and FIG. 5B are views that illustrate an example of
a punch of a clinching tool;
[0019] FIG. 6 is a view for explaining a method of applying
lubricant to an end portion of a hub spindle;
[0020] FIG. 7 is a sectional view that illustrates an existing
vehicle hub unit;
[0021] FIG. 8 is an enlarged view that illustrates an end portion
of a clinched portion of the vehicle hub unit shown in FIG. 7;
[0022] FIG. 9 is a sectional view for explaining an existing
manufacturing method; and
[0023] FIG. 10 is an enlarged view of a main portion in FIG. 9.
DETAILED DESCRIPTION OF EMBODIMENTS
[0024] Hereinafter, a manufacturing method for a vehicle hub unit
according to an embodiment of the invention will be described in
detail with reference to the accompanying drawings.
[0025] First, the configuration of the vehicle hub unit
manufactured by the manufacturing method according to the
embodiment of the invention will be described. FIG. 1 is a
sectional view that illustrates an example of the vehicle hub unit
1 manufactured by the manufacturing method according to the
embodiment of the invention. FIG. 2 is an enlarged view that
illustrates an end portion of a clinched portion of the vehicle hub
unit.
[0026] The vehicle hub unit 1 supports a wheel of an automobile
such that the wheel is rotatable with respect to a suspension. The
vehicle hub unit 1 includes a hub wheel 3, an outer ring 5 and a
plurality of rolling elements 6. The hub wheel 3 has a cylindrical
hub spindle 2. An inner ring member 4 is fixed to one end (right
end portion in FIG. 1) of the hub spindle 2 by clinching. The outer
ring 5 is arranged radially outward of the hub spindle 2. The
rolling elements 6 each are rollably arranged between an outer ring
raceway 5a of the inner peripheral surface of the outer ring 5 and
an inner ring raceway 2a of the outer peripheral surface of the hub
spindle 2 or between an outer ring raceway 5b of the inner
peripheral surface of the outer ring 5 and an inner ring raceway 4a
of the outer peripheral surface of the inner ring member 4. The
rolling elements 6 are retained by a cage 20, and arranged at
predetermined intervals in the circumferential direction. Seal
members 21 are provided in an annular space formed between the
outer ring 5 and the hub wheel 3. The seal members 21 close the
annular space from both ends of the annular space in the axial
direction.
[0027] A flange portion 7 is formed at the end portion (left end
portion in FIG. 1) of the hub wheel 3. A wheel of a tire, a brake
disc, and the like (not shown), are fitted to the flange portion 7
with bolts. In FIG. 1, a reference numeral 7a denotes a hole into
which a bolt is inserted. A fixing flange 8 is formed on the outer
peripheral surface of the outer ring 5. The fixing flange 8 is used
to fit the hub unit 1 to a vehicle body-side member (not shown)
supported by the suspension of a vehicle.
[0028] The hub spindle 2 is a single-piece member that has a
large-diameter portion 9 and a small-diameter portion 11. The
large-diameter portion 9 is formed at a position near the flange
portion 7. The small-diameter portion 11 is smaller in diameter
than the large-diameter portion 9, and is formed so as to be
contiguous with the large-diameter portion 9 via a step 10. The
inner ring raceway 2a is formed in the outer peripheral surface of
the large-diameter portion 9. The inner ring raceway 2a corresponds
to the outer ring raceway 5a of the outer ring 5.
[0029] The inner ring member 4 is fitted onto the outer peripheral
surface of the small-diameter portion 11 of the hub spindle 2, and
then an end portion of the small-diameter portion 11 is clinched to
form a clinched portion 12, as will be described later. In this
way, the inner ring member 4 is fixed between the step 10 and the
clinched portion 12.
[0030] Driving force of a drive shaft 31 is transmitted to the hub
unit 1 via a constant velocity joint 30. The constant velocity
joint 30 shown in the drawing is a Birfield constant velocity
joint. The constant velocity joint 30 includes an inner ring 32, a
plurality of balls 34 and a cage 35. The inner ring 32 is joined to
one end of the drive shaft 31. The balls 34 are arranged between
the inner ring 32 and an outer ring 33 that is arranged radially
outward of the inner ring 32. The cage 35 retains the balls 34.
[0031] The outer ring 33 of the constant velocity joint 30 has a
bowl-shaped outer ring cylindrical portion 33a and an outer ring
shaft portion 33b. The outer ring shaft portion 33b extends from a
center portion of an end surface of the outer ring cylindrical
portion 33a. The outer ring shaft portion 33b has a hole 36 that
extends in the axial direction. The inner peripheral surface of the
outer ring shaft portion 33b, which defines the hole 36, has an
internal thread. The hub unit 1 is connected to the constant
velocity joint 30 by a cap bolt 38 that has an external thread 37
at its end portion.
[0032] As shown in FIG. 2, a spline tooth portion 13 is formed at
the end surface of the clinched portion 12 of the end portion of
the hub spindle 2. A tooth portion 14 is formed at the end surface
of the outer ring cylindrical portion 33a, which faces the clinched
portion 12. Owing to the mesh of the spline tooth portion 13 and
the tooth portion 14, rotational driving force of the drive shaft
31 is transmitted to the hub unit 1 via the constant velocity joint
30.
[0033] The number of teeth 13a of the spline tooth portion 13 is
37, a protruding portion 15 is formed at each bottom 13b between
the consecutive teeth 13a. Each protruding portion 15 protrudes
toward the tooth portion 14 of the outer ring cylindrical portion
33a that faces the spline tooth portion 13. Each protruding portion
15 is formed at a radially inner portion of the bottom 13b of the
spline tooth portion 13. More specifically, each protruding portion
15 is formed at the bottom 13b at a portion substantially radially
inward of a meshing portion 16 (hatched portion in FIG. 2) at which
the tooth 13a of the spline tooth portion 13 is in mesh with a
tooth 14a of the tooth portion 14 of the outer ring cylindrical
portion 33a. By forming the protruding portions 15, the stiffness
of each of the teeth 13a that constitute the spline tooth portion
13 is increased. Thus, the allowable loading torque for the hub
unit 1 is increased.
[0034] A predetermined clearance C1 is left between each bottom 13b
of the spline tooth portion 13, including the surface of the
protruding portion 15, and a top surface 14c of the tooth 14a of
the tooth portion 14 of the outer ring cylindrical portion 33a,
which faces the bottom 13b. On the other hand, a predetermined
clearance C2 is left between a top surface 13c of each tooth 13a of
the spline tooth portion 13 and a bottom 14b of the tooth portion
14 of the outer ring cylindrical portion 33a, which faces the top
surface 13c.
[0035] Both the spline tooth portion 13 and the tooth portion 14 of
the outer ring cylindrical portion 33a are formed by closed die
forging. The predetermined clearances C1 and C2 are set such that
tolerances in closed die forging are absorbed so as not to cause
contact between the teeth when the constant velocity joint 30 is
fitted to the hub unit 1. Although the clearances C1 and C2 vary
depending on the accuracy of closed die forging, the clearances C1
and C2 are usually approximately 0.5 to 1 mm.
[0036] A manufacturing method for the vehicle hub unit will be
described below. The above-described spline tooth portion 13 is
formed together with the clinched portion 12 at the same time by
fitting the inner ring member 4 onto the outer peripheral surface
of the small-diameter portion 11 of the hub spindle 2 and then
subjecting the end portion of the small-diameter portion 11 to
closed die forging.
[0037] Closed die forging may be performed using a clinching tool.
FIG. 5A and FIG. 5B show an example of such a clinching tool 40.
The clinching tool 40 includes a punch 42 and an oscillating
spindle 43 to which the punch 42 is non-rotatably attached. The
punch 42 has a guide portion 41 that is configured to be inserted
into the end portion of the small-diameter portion 11 and that is
configured to be brought into contact with the end portion with a
predetermined inclination angle with respect to the inner
peripheral surface of the end portion.
[0038] As shown in FIG. 3 and FIG. 4, the hub wheel 3 is placed on
a base 46, from which multiple knock-pins 45 extend, such that the
outer-side (side close to the outer side of the vehicle when the
hub unit 1 is attached to the vehicle) side surface of the flange
portion 7 is in contact with the base 46. Then, the knock-pins 45
are inserted into the holes 7a of the flange portion 7 to fix the
hub wheel 3 to the base 46.
[0039] The guide portion 41 of the punch 42 has a projecting shape
that projects from the center portion of one end surface of the
punch 42. A tooth profile 42a is formed in the one end surface of
the punch 42, at a portion radially outward of the base of the
guide portion 41. The tooth profile 42a is used to plastically form
the spline tooth portion 13. A recess 44 having a shape
corresponding to each protruding portion 15 of the spline tooth
portion 13 is formed at a radially inner side portion of each
protruding portion 42b of the punch 42, which corresponds to the
bottom of the spline tooth portion 13. During closed die forging,
the recesses 44 are used to form the protruding portions 15 of the
spline tooth portion 13.
[0040] When the clinched portion 12 and the spline tooth portion 13
are formed, first, the clinching tool 40 is inserted into the
small-diameter portion 11 of the hub spindle 2 of the hub wheel 3.
Subsequently, the punch 42 of the clinching tool 40 is pressed
against the end portion of the small-diameter portion 11 with
predetermined pressing force, and a spindle (not shown) that is
coaxial with the hub spindle 2 is rotated to oscillate the
clinching tool 40. Through the oscillating clinching, the
small-diameter portion 11 is plastically deformed radially outward
and the clinched portion 12 is formed, and, at the same time, the
spline tooth portion 13 is formed at the end surface of the
clinched portion 12 by the tooth profile of the punch 42.
[0041] In the embodiment of the invention, the punch 42 has the
guide portion 41. The guide portion 41 is configured to contact the
end portion of the small-diameter portion 11 with a predetermined
angle with respect to the inner peripheral surface of the
small-diameter portion 11 of the hub spindle 2. Therefore, plastic
deformation of the small-diameter portion 11 toward the radial
center of the sub spindle 2 during oscillating clinching is
suppressed. Accordingly, the predetermined protruding portions 15
are accurately formed at a radially inner side portion of the
spline tooth portion 13. Thus, it is possible to avoid contact
between the hub wheel 3 and the constant velocity joint 30 when the
constant velocity joint 30 is fitted to the hub unit 1.
[0042] In addition, in the present embodiment, an annular
restraining member 70 is arranged radially outward of the inner
ring member 4. The restraining member 70 is used to prevent the
inner ring member 4 from deforming radially outward due to pressure
applied from the punch 42 during oscillating clinching. As shown in
FIG. 4, the restraining member 70 has an annular body 71, an
annular protruding portion 72 and a guide 73. The annular
protruding portion 72 axially protrudes from the inner peripheral
portion of one end surface of the annular body 71. The guide 73 is
formed on the inner peripheral surface of the annular body 71. The
annular protruding portion 72 is inserted into an annular space
between the outer peripheral surface of the inner ring member 4
fitted around the small-diameter portion 11 of the hub spindle 2
and the inner peripheral surface of the inner-side (side close to
the inner side of the vehicle when the hub unit 1 is attached to
the vehicle) end portion of the outer ring 5. Then, the length of
the inside diameter of the annular protruding portion 72 and
annular body 71 is adjusted such that the inner peripheral surface
of the annular protruding portion 72 contacts the outer peripheral
surface of the inner ring member 4 fitted around the small-diameter
portion 11 of the hub spindle 2. In addition, when the restraining
member 70 is arranged, the guide 73 contacts the inner-side end
surface of the inner ring member 4. Therefore, it is possible to
easily determine the position of the restraining member 70 in the
up-down direction (axial direction).
[0043] When the restraining member 70 is used, the radially outer
side portion of the inner ring member 4 close to the inner ring
raceway 4a is restrained by the restraining member 70. Therefore,
deformation of the inner ring member 4 during clinching is
suppressed, and it is possible to prevent occurrence of indentation
in the inner ring raceway 4a.
[0044] The protrusion height of the annular protruding portion 72
in the axial direction is adjusted to such a height that the inner
peripheral surface of the annular protruding portion 72 contacts a
portion of the outer peripheral surface of the inner ring member 4,
on which the seal member 21 will be arranged. If the protrusion
height of the annular protruding portion 72 in the axial direction
is adjusted in this way, even when an annular recess 4d is formed
in the inner-side end portion of the inner ring member 4 in order
to fit an annular dust cover 80 (see FIG. 2) used to prevent entry
of dust toward the spline tooth portion 13, the restraining member
70 is arranged so as to cover a portion of the outer peripheral
surface (the diameter of this portion of the outer peripheral
surface is larger than the diameter of a portion at which the
recess is formed) of the inner ring member 4, the portion being
further axially inward than the recess 4d in the bearing.
Therefore, it is possible to reliably suppress deformation of the
inner ring member 4 during clinching.
[0045] The protrusion height of the annular protruding portion 72
in the axial direction is set to such a height that a distance of
approximately 0.5 mm is ensured between the end surface of the
annular protruding portion 72 and an inner ring shoulder portion 4c
that is the boundary between the inner ring raceway 4a and outer
peripheral surface 4b of the inner ring member 4. Thus, it is
possible to prevent contact between the end surface of the annular
protruding portion 72 and the rolling elements 6 during oscillating
clinching.
[0046] When the end portion of the small-diameter portion 11 of the
hub spindle 2 is clinched by oscillating clinching and the spline
tooth portion 13 is formed at the clinched portion 12, lubricant,
for example, lubricating oil, is usually used in order to extend
the service life of the punch 42 and to stabilize the accuracy of
teeth formed. In this case, lubricating oil may be sprayed onto a
lubrication portion, that is, the end portion of the small-diameter
portion 11 of the hub spindle 2. However, when the lubricating oil
is sprayed, there is a problem that it is difficult to stabilize
the amount of applied lubricating oil and, in addition, lubricating
oil adheres to portions other than the portion that need
lubrication. Then, there is another problem that the number of
cleanup works for equipment increases due to the lubricating oil
scattering or adhering to the portions other than the portion that
needs lubrication.
[0047] In contrast to this, in order to spray lubricating oil only
to portions that need lubrication, an additional device, such as
masking, is required. Therefore, there is yet another problem that
not only the equipment becomes complex but also the working process
becomes complicated.
[0048] Then, in the present embodiment, as shown in FIG. 6,
lubricant is applied to the end portion of the small-diameter
portion 11 of the hub spindle 2 with the use of an applicator 90
made of spongy porous material, instead of being sprayed. Thus, the
used amount of lubricant is minimized. In addition, lubricant does
not scatter to portions around a portion that needs lubrication,
unlike the case where lubricant is applied by spraying. Therefore,
the number of cleanup works for equipment is reduced.
[0049] The applicator 90 is formed of a first applicator 93 and a
second applicator 94. The first applicator 93 is immersed in
lubricating oil 92 stored in a container 91. The second applicator
94 contacts the first applicator 93 to absorb the lubricating
oil.
[0050] The first applicator 93 is formed of a disc-shaped body 93a
and a cylindrical absorbing portion 93b. The body 93a has a hole at
its center. The absorbing portion 93b is inserted into the hole of
the body 93a. The body 93a of the first applicator 93 is arranged
on the upper surface of a perforated partition panel 91a of the
container 91. The absorbing portion 93b extends through the hole
91b of the perforated partition panel 91a, and is immersed in the
lubricating oil 92 in the container 91. The lubricating oil 92 is
absorbed by the absorbing portion 93b and spreads all around the
body 93a. In this case, because the absorbing portion 93b has a
cylindrical shape, it is possible to ensure a large contact area at
which the absorbing portion 93b contacts the lubricating oil 92 in
the container 91, and the body 93a efficiently absorbs the
lubricating oil 92.
[0051] When the second applicator 94 is brought into contact with
the body 93a, the second applicator 94 absorbs an appropriate
amount of lubricating oil. When the second applicator 94 that has
absorbed the appropriate amount of lubricating oil is brought into
contact with the end portion of the small-diameter portion 11 of
the hub spindle 2 in a stamping manner, an optimal amount of
lubricating oil is uniformly applied to only forged portions. The
second applicator 94 is moved by forming the hole at the center of
the second applicator 94, inserting a columnar engaging portion
(not shown) of a transferring mechanism into the hole, and moving
the transferring mechanism by appropriate driving means.
[0052] Note that the stamping application method using the
above-described applicator 90 made of spongy porous material is not
limited to the case where a spline tooth portion is machined by
oscillating clinching, and the application method may also be
applied to another general oscillating clinching in which a spline
tooth portion is not formed.
[0053] The invention is not limited to the above-described
embodiment, and various modifications and changes may be made
within the scope of the appended claims. For example, in the
above-described embodiment, the sectional shape of each protruding
portion is a wavy shape. Alternatively, another sectional shape,
such as a semi-circular shape and a trapezoidal shape, may be
employed. In addition, in the above-described embodiment, there is
employed a third-generation structure in which an inner ring
raceway is directly formed in the outer periphery of the hub
spindle. Alternatively, a first-generation or second-generation
structure in which a pair of inner rings is press-fitted onto a hub
spindle may be employed. In addition, in the above-described
embodiment, the peripheral surface (in the sectional view shown in
FIG. 5A and FIG. 5B, the portion shown by the oblique line of a
trapezoid) of the guide portion 41 of the punch 42 is a flat
surface. Alternatively, the peripheral surface may be formed in a
curved surface.
[0054] In the manufacturing method according to the invention, the
guide portion that projects from the center portion of one end
surface of the punch suppresses plastic deformation of the hub
spindle end portion toward radial center of the hub spindle during
oscillating clinching. Therefore, it is possible to avoid contact
between the hub wheel and the constant velocity joint when the
constant velocity joint is fitted to the hub unit.
* * * * *