U.S. patent application number 13/673048 was filed with the patent office on 2013-11-21 for outer ring for rocking bearing, retainer for rocking bearing, rocking bearing, and air disk brake system.
The applicant listed for this patent is Akihiko KATAYAMA, Shinji OISHI, Haruki YAMADA. Invention is credited to Akihiko KATAYAMA, Shinji OISHI, Haruki YAMADA.
Application Number | 20130308888 13/673048 |
Document ID | / |
Family ID | 39324469 |
Filed Date | 2013-11-21 |
United States Patent
Application |
20130308888 |
Kind Code |
A1 |
OISHI; Shinji ; et
al. |
November 21, 2013 |
Outer ring for rocking bearing, retainer for rocking bearing,
rocking bearing, and air disk brake system
Abstract
An outer ring for rocking bearing (11a) includes a raceway
surface (12a) on the inner diameter side and has flange parts (13a)
and (13b) provided by bending axial both ends to the inner diameter
side. The flange parts (13a) and (13b) are provided with bent parts
(17a) and (17b) axially bent toward the raceway surface (12a) side
so as to enfold a retainer arranged on the inner diameter side.
Thus, the retainer can be enfolded by the bent parts (17a) and
(17b). Therefore, even when the retainer comes to be moved to the
inner diameter side of the outer ring for rocking bearing (11a),
the retainer is caught by the bent parts (17a) and (17b), so that
the movement of the retainer to the inner diameter side is
restricted and rollers and the retainer can be prevented from
dropping off.
Inventors: |
OISHI; Shinji; (Iwata-shi,
JP) ; YAMADA; Haruki; (Hamamatsu-shi, JP) ;
KATAYAMA; Akihiko; (Kikugawa-shi, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
OISHI; Shinji
YAMADA; Haruki
KATAYAMA; Akihiko |
Iwata-shi
Hamamatsu-shi
Kikugawa-shi |
|
JP
JP
JP |
|
|
Family ID: |
39324469 |
Appl. No.: |
13/673048 |
Filed: |
November 9, 2012 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
12312067 |
Apr 24, 2009 |
8313246 |
|
|
PCT/JP2007/070359 |
Oct 18, 2007 |
|
|
|
13673048 |
|
|
|
|
Current U.S.
Class: |
384/569 ;
384/572 |
Current CPC
Class: |
F16C 33/585 20130101;
F16C 2361/45 20130101; F16C 33/467 20130101; F16C 19/26 20130101;
F16D 2121/14 20130101; F16D 2125/32 20130101; F16D 65/18 20130101;
F16C 33/62 20130101; F16C 19/502 20130101; F16C 33/46 20130101;
F16C 33/64 20130101; F16C 33/4605 20130101 |
Class at
Publication: |
384/569 ;
384/572 |
International
Class: |
F16C 33/46 20060101
F16C033/46; F16C 19/26 20060101 F16C019/26 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 26, 2006 |
JP |
2006-291493 |
Oct 26, 2006 |
JP |
2006-291494 |
Nov 6, 2006 |
JP |
2006-300245 |
Nov 21, 2006 |
JP |
2006-313822 |
Nov 30, 2006 |
JP |
2006-323274 |
Dec 4, 2006 |
JP |
2006-326667 |
Claims
1-34. (canceled)
35. A retainer for rocking bearing comprising: a pair of connection
parts extending in a circumferential direction; and a plurality of
column parts connecting said pair of connection parts to each other
to form a plurality of pockets to hold rollers between said
adjacent column parts, wherein the radial outermost part of said
column part is arranged apart from a pitch circle formed by
connecting rotation centers of said rollers.
36. A rocking bearing comprising: an outer ring for rocking bearing
containing a raceway surface on the inner diameter side and having
a flange part provided by bending axial each end to the inner
diameter side; a plurality of rollers arranged on said raceway
surface; and the retainer for rocking bearing according to claim
35.
37. A retainer for rocking bearing comprising: a pair of connection
parts extending in a circumferential direction; and a plurality of
column parts connecting said pair of connection parts to each other
to form a plurality of pockets to hold the rollers between said
adjacent column parts, and satisfying a relation:
{.theta./(n-1)}.degree.<a.sub.0<90.degree. wherein n
represents the number of rollers housed in said pockets, a.sub.0
represents an angle formed between opposed wall surfaces of said
adjacent column parts, and .theta. represents a center angle formed
between rotation centers of the rollers housed in said pockets
positioned at circumferential both ends.
38. A rocking bearing comprising: an outer ring for rocking bearing
containing a raceway surface on the inner diameter side and having
a flange part provided by bending axial each end to the inner
diameter side; a plurality of rollers arranged on said raceway
surface; and the retainer for rocking bearing according to claim
37.
Description
TECHNICAL FIELD
[0001] The present invention relate to an outer ring for a rocking
bearing, a retainer for a rocking bearing, a rocking bearing, and
an air disk brake system.
BACKGROUND ART
[0002] An air disk brake system using compressed air is employed in
a large-sized commercial motor vehicle such as a track and a bus.
Here, a brief description will be made of a constitution of a
general air disk brake system. FIG. 40 is a schematic sectional
view showing the constitution of the general air disk brake system.
Referring to FIG. 40, an air disk brake system 101 includes a brake
cylinder (not shown) having an actuator rod 102, a lever 103
connected to one end of the actuator rod 102, a rotation member 104
connected to the other end of the lever 103, a rocking bearing 105
rotatably supporting the rotation member 104, a connection part 107
provided at an eccentric position with respect to the rotation
member 104, a traverse 106 having one end connected to the
connection part 107, right and left brake pads (not shown) working
with the traverse 106, and a rotor (not shown) arranged between the
right and left brake pads. According to the air disk brake system
101, the rotor is sandwiched by the right and left brake pads by
use of the compressed air supplied from the brake cylinder through
the lever 103 and the like.
[0003] In addition, such air disk brake system is disclosed in
Japanese National Publication PCT application No. 8-504250 and
WO2006/002905A1.
[0004] A brief description will be made of a constitution of the
rocking bearing in the above air disk brake system. The rocking
bearing has an outer ring for the rocking bearing, a plurality of
rollers, and a retainer to retain the rollers. The outer ring for
the rocking bearing is not in the form of a ring, and it is
provided by splitting a cylindrical member at two circumferential
points. The retainer also has a configuration provided by splitting
a cylindrical member at two circumferential points and following
the outline of the outer ring for the rocking bearing. When the
rocking bearing having the above constitution is assembled, the
rollers are incorporated in pockets of the retainer first, and the
retainer having the rollers is arranged on the inner diameter side
of the outer ring for the rocking bearing.
[0005] Here, after the rocking bearing has been assembled, the
movement of the retainer toward the inner diameter side is not
restricted. Thus, when the assembled rocking bearing is mounted on
the air disk brake system having the above constitution, the
retainer could be moved toward the inner diameter side and drop out
of the outer ring for the rocking bearing.
DISCLOSURE OF THE INVENTION
[0006] It is an object of the present invention to provide an outer
ring for a rocking bearing in which rollers and a retainer are
prevented from dropping off.
[0007] It is another object of the present invention to provide a
rocking bearing having high assembling properties.
[0008] It is still another object of the present invention to
provide an air disk brake system having high productivity.
[0009] An outer ring for a rocking bearing according to the present
invention includes a raceway surface on the inner diameter side and
has a flange part provided by bending axial each end to the inner
diameter side. Here, at least one the flange part is provided with
a bent part axially bent toward the raceway surface side so as to
enfold a retainer arranged on the inner diameter side.
[0010] In this constitution, at the time of assembling of the
rocking bearing assembling, when the retainer having the rollers is
arranged on the inner diameter surface of the outer ring for the
rocking bearing, the retainer can be enfolded by the bent part.
Thus, even when the retainer comes to be moved toward the inner
diameter side of the outer ring for the rocking bearing, the
retainer is caught by the bent part, so that the movement of the
retainer toward the inner diameter side can be restricted. Thus,
the rollers and retainer can be prevented from dropping out of the
outer ring for the rocking bearing.
[0011] Preferably, the bent part is provided so as to be continued
in a circumferential direction of the flange part. Thus, since the
retainer can be enfolded over the wide range in the circumferential
direction, the retainer and the roller can be prevented from
dropping off more surely.
[0012] Further preferably, the bent part is provided along each
flange part. Thus, the retainer can be held by the bent part
provided on each flange part. Thus, the rollers and retainer can be
prevented from dropping out of the outer ring for the rocking
bearing more surely.
[0013] Further preferably, a material containing 0.15 to 1.1% by
weight of carbon is subjected to a carbonitriding treatment to
produce the outer ring for the rocking bearing. Thus, high-strength
outer ring for the rocking bearing can be produced at low cost.
Since the outer ring for the rocking bearing has high load
capacity, it is hardly damaged. In addition, since the strength of
the bent part is also high, the retainer and the rollers can be
prevented from dropping off more surely.
[0014] In addition, the material of the outer ring for the rocking
bearing may contain 0.5 to 1.1% by weight of carbon. According to
the above constitution, processability is improved, and its outline
configuration can be formed with high accuracy by a pressing
process. In addition, even when the carbonitriding treatment is not
performed, hardness required for the outer ring for the rocking
bearing can be provided. Thus, the outer ring for the rocking
bearing can be prevented from being deformed at the time of heat
treatment. Therefore, the outer ring for the rocking bearing is
high in accuracy, low in cost, and high in load capacity.
[0015] Further preferably, the outer ring for the rocking bearing
containing 0.5 to 1.1% by weight of carbon is subject to a bright
quenching treatment. In addition, the outer ring for the rocking
bearing containing 0.5 to 1.1% by weight of carbon may be subject
to a high-frequency quenching treatment. The above heat treatments
can be performed at low cost.
[0016] According to another aspect of the present invention, a
rocking bearing includes a plurality of rollers arranged on the
raceway surface, a retainer containing pockets to hold the rollers
and a pair of connection parts positioned on axial each end of the
pockets and continued in a circumferential direction, and any one
of the outer rings for the rocking bearing described above.
[0017] According to the rocking bearing, the rollers and the
retainer are prevented from dropping out of the outer ring for the
rocking bearing. In addition, at the time of assembling, since the
retainer and the outer ring for the rocking bearing are prevented
from being separated or shifted, a mounting defect can be also
prevented. Therefore, the assembling properties can be
improved.
[0018] Preferably, an engagement part engaging with the bent part
is provided at the connection part. Thus, when the bent part
engages with the engagement part, the retainer and the roller can
be more surely prevented from dropping off, and the assembling
properties an be further improved.
[0019] Further preferably, the outer ring for the rocking bearing
and/or the roller have a nitride enrichment layer, and an austenite
grain size number exceeding 10, and contains 11% to 25% by volume
of retained austenite, and 0.1% to 0.7% by weight of nitrogen.
[0020] When the roller bearing such as the rocking bearing is
reduced in size, the problem is that an applied load per unit area
is increased and the life is shortened. Therefore, it is inevitable
that the life is shortened when the roller bearing is reduced in
size.
[0021] Here, when the austenite grain of the above bearing member
is miniaturized such that its grain size number exceeds 10, the
rolling fatigue life can be considerably elongated. When the
austenite grain size number is not more than 10, since the rolling
fatigue life is not sufficiently elongated, the number should be
more than 10. In general, it is to be not less than 11. In
addition, an average grain size may be not more than 6 .mu.m. A
finer austenite grain size is better, but it is difficult get the
grain size number exceeding 13 in general. The above austenite
grain size may be found by a normal method defined in JIS or may be
calculated by finding an average grain size corresponding to the
grain size number by a section method.
[0022] In addition, the austenite grain is not changed even in a
surface layer having a nitrogen enrichment layer, and in the inner
side thereof. Therefore, the grain size number is to be within the
above range at the surface layer and its inner side. Here, the
austenite grain is the phase-transformed austenite grain during the
quenching treatment, which means that it remains as a past history
even after transformed to martensite.
[0023] In addition, when the retained austenite is less than 11% by
volume, the surface damage life is considerably lowered, and when
the retained austenite is more than 25% by volume, an aging length
change deteriorates because there is no difference from the
retained austenite volume when the normal carbonitriding treatment
is performed.
[0024] The retained austenite volume is a value at a surface layer
of 50 .mu.m from a rolling surface after ground, and can be
measured by comparing the diffraction intensity of martensite
.alpha. (211) with that of retained austenite .gamma. (220). As
another example, it can be measured by finding magnetization force
by a magnetic scale, using the fact that an austenite phase is a
nonmagnetic body and a ferrite phase is a ferromagnetic body. Or,
it can be easily measured by use of a commercially available
measurement device.
[0025] The nitrogen enrichment layer is a layer in which a nitrogen
content is increased, and formed in a surface layer by the
carbonitriding treatment or the nitriding treatment. When the
nitrogen content of the nitrogen enrichment layer is less than 0.1%
by weight, there is no effect, and the surface damage life is
shortened especially. Meanwhile, the nitrogen content is more than
0.7% by weight, a void is generated and hardness is not provided
because of too many retained austenite, whereby the life is
shortened. The nitrogen content of the nitrogen enrichment layer is
a value at 50 .mu.m of the surface layer from the rolling surface
after ground, and it can be measured by EPMA (Electron Probe
Micro-Analysis wavelength-dispersive X-ray microanalyzer).
[0026] As described above, according to this constitution, the
rocking bearing containing the above outer ring for the rocking
bearing and the rollers can have a long life.
[0027] Further preferably, a snap fitting allowable configuration
part to allow snap fitting is provided in the retainer and/or the
bent part so that the retainer is retained by the bent part after
passing through the bent part.
[0028] According to this constitution, when the retainer is held by
the bent part of the outer ring for the rocking bearing through the
bent part, the retainer is snap-fit in the outer ring for the
rocking bearing by the snap fitting allowable configuration
provided at the retainer and/or the bent part, and the retainer can
be held by the bent part of the outer ring for the rocking bearing.
Since the bent part holds the retainer so as to enfold it, the
retainer can be prevented from being separated from the outer ring
for the rocking bearing. In addition, since the snap fitting
allowable configuration part uses elastic deformation of the
retainer and the outer ring for the rocking bearing, when the
retainer is assembled in the outer ring for the rocking bearing, it
can be easily fit in without needing strong force. In addition, at
the time of assembling, the retainer and the outer ring for the
rocking bearing can be prevented from being damaged. Therefore, the
assembling properties of the rocking bearing are improved.
[0029] Further preferably, the snap fitting allowable configuration
includes a fitting click axially projecting from the end face of
the connection part. Thus, the snap fitting can be implemented by
use of the fitting click projecting in the axial direction.
[0030] Further preferably, a corner part of the fitting click is
chamfered on the outer diameter side. Thus, the snap fitting can be
implemented by use of the chamfered part of the fitting click.
Thus, the snap fitting can be implemented smoothly. Therefore, the
assembling properties can be further improved.
[0031] Further preferably, a corner part of the bent part is
chamfered on the inner diameter side. Thus, the snap fitting is
implemented by use of the chamfered part of the bent part. Thus,
the snap fitting can be implemented smoothly. Therefore, the
assembling properties can be further improved.
[0032] Further preferably, the fitting click is provided at a
circumferential position provided with the pocket. The
circumferential position of the pocket is not connected in the
axial direction. Thus, the retainer can be easily elastically
deformed in the axial direction at the circumferential position of
the fitting click. Therefore, the assembling properties can be
further improved.
[0033] Further preferably, the fitting click is provided at each
connection part, and the circumferential position of the fitting
click provided at one connection part is different from the
circumferential position of the fitting click provided at the other
connection part. Thus, the circumferential positions of the elastic
deformation can be differentiated between the fitting click
provided at the one connection part and the fitting click provided
at the other connection part. Therefore, the retainer can be easily
elastically deformed in the axial direction, so that the assembling
properties are further improved.
[0034] Further preferably, the snap fitting allowable configuration
is provided at the connection part, and contains a slit recessed in
a radial direction. Thus, the snap fitting can be implemented by
use of the slit recessed in the radial direction.
[0035] Further preferably, the outer ring for the rocking bearing
satisfies a relation 0.2W.sub.2<W.sub.1<0.8W.sub.2 wherein
W.sub.1 represents an axial length of the slit, and W.sub.2
represents an axial length of the connection part, and a relation
0.2H.sub.2<H.sub.1<0.8H.sub.2 wherein H.sub.1 represents an
radial length of the slit, and H.sub.2 represent an radial length
of the connection part. Thus, the elastic deformation can be
appropriately implemented at the time of snap fitting. That is,
when the length dimensional relation of the slit is within the
above range, the retainer can be elastically deformed by
appropriate force and the snap fitting can be implemented without
damaging the retainer.
[0036] Further preferably, a projection part is provided at a
predetermined position of an axial end face of the connection part,
and a click part is provided at the outer ring for the rocking
bearing to limit the movement amount of the retainer by abutting on
the projection part after the retainer is moved a predetermined
amount in a circumferential direction with respect to the outer
ring for the rocking bearing.
[0037] According to the above constitution, even when the retainer
is moved in the circumferential direction, the projection part
provided at the predetermined position of the connection part abuts
on the click part provided at the outer ring for the rocking
bearing. Then, the retainer cannot be moved in the circumferential
direction any more. Thus, the circumferential movement of the
retainer can be restricted. In addition, according to the rocking
bearing having the above constitution, when the projection part is
provided at the optional position, the circumferential movement
amount of the retainer can be optionally determined. Thus, the
retainer can be moved beyond the circumferential end of the outer
ring for the rocking bearing. In addition, it is not necessary
provide a new member. Therefore, the range of movement of the
retainer can be increased in the inexpensive constitution. In
addition, according to the rocking bearing, since the retainer is
prevented from dropping off, the assembling properties can be
improved.
[0038] Further preferably, the predetermined position of the
projection part is on the circumferential inner side of the pocket
arranged circumferential outermost side, and the movement of the
retainer is limited after a part of the retainer projects from the
circumferential one end side of the outer ring for the rocking
bearing. Thus, even when the predetermined position of the
projection part is on the circumferential inner side than the
pocket arranged on the circumferential outermost side, the
circumferential movement of the retainer is limited and restricted
under the condition that the circumferential end of the retainer
projects from the one end of the outer ring for the rocking
bearing. Therefore, the movement range of the retainer can be
further increased.
[0039] Further preferably, a circumferential length of the retainer
projecting from the outer ring for the rocking bearing is not more
than a circumferential length from the one end side of the retainer
to the pocket arranged on the circumferential outermost side of the
one end side thereof. Thus, the roller housed in the pocket
arranged on the outermost side can be prevented from dropping off.
Therefore, the assembling properties of the rocking bearing can be
further improved.
[0040] Further preferably, the click part and the projection part
are provided axial each end. Thus, since the projection part
engages with the click part on axial each side, the assembling
properties can be further improved.
[0041] In addition, a rocking bearing includes any one of the outer
rings for the rocking bearing described above, a plurality of
rollers arranged on the raceway surface, a retainer for the rocking
bearing having a pair of connection parts extending in a
circumferential direction, and a plurality of column parts
connecting the pair of connection parts to each other to form a
plurality of pockets to hold the rollers between the adjacent
column parts, and the radial outermost part of the column part is
arranged apart from a pitch circle formed by connecting rotation
centers of the rollers.
[0042] According to the retainer for the rocking bearing, the
distance between the adjacent rollers is smallest on a pitch
circle. Therefore, when the column part is provided apart from the
pitch circle, the distance between the adjacent rollers can be
small. As a result, the number of the rollers can be increased in
the retainer for the rocking bearing, so that the rocking bearing
is high in load capacity.
[0043] Preferably, the rocking bearing satisfies a relation
B.sub.2<0.98<B.sub.4 wherein B.sub.2 represent an outer
diameter of the column part, and B.sub.4 represents a diameter of
the pitch circle. Thus, when the column part is arranged on the
inner side of the pitch circle, the roller in the pocket can be
prevented from dropping off toward the radial inner side. In
addition, the roller can be prevented from dropping off toward the
radial outer side by the outer rings for the rocking bearing in
general.
[0044] Further preferably, the rocking bearing satisfies:
0.9 < ( n - 1 ) .times. l L < 1.0 [ Formula 1 ]
##EQU00001##
wherein n represents the number of rollers housed in the pockets, l
represents a length of the pitch circle overlapping with the
roller, and L represents a circumferential length of the pitch
circle between the rotation centers of the rollers housed in the
pockets positioned at circumferential both ends.
[0045] The formula 1 designates an occupancy of the roller on a
circumference of the pitch circle. Referring to the formula 1, when
the occupancy of the roller is not more than 0.9, the distance
between the adjacent rollers is too long and sufficient load
capacity cannot be provided. Meanwhile, when the distance between
the adjacent rollers is small, the rollers could be in contact with
each other at the time of rocking. This causes oil film cutting and
heat generation on the roller surface. Thus, the occupancy needs to
be less than 1.0.
[0046] Further preferably, the retainer for the rocking bearing is
formed of a material containing polyamide 46, and 5% to 20% by
weight of a fiber filler material. The resin retainer produced of a
resin material by projection part molding has high degree of
freedom in configuration. In addition, when the fiber filler
material such as carbon fiber and glass fiber is contained, the
strength required for the retainer can be provided.
[0047] In addition, when the content of the fiber filler material
is less than 5% by weight, it is hard to get strength required for
the retainer for the rocking bearing. Meanwhile, when it is more
than 20% by weight, fluidity of the resin material at the time of
molding deteriorates. This could cause a problem such as gas
burning and lack of filling in producing the retainer having many
pockets and thin column parts. Furthermore, when a filling pressure
is increased to solve the problem, a burr could be generated.
Therefore, the content of the fiver filler material is to be within
the above range.
[0048] A retainer for a rocking bearing according to the present
invention includes a pair of connection parts extending in a
circumferential direction, and a plurality of column parts
connecting the pair of connection parts to each other to form a
plurality of pockets to hold rollers between the adjacent column
parts. The radial outermost part of the column part is arranged
apart from a pitch circle formed by connecting rotation centers of
the rollers.
[0049] A rocking bearing includes any one of the outer rings for
the rocking bearing described above, a plurality of rollers
arranged on the raceway surface, and a retainer for the rocking
bearing having a pair of connection parts extending in a
circumferential direction and a plurality of column parts
connecting the pair of connection parts to form a plurality of
pockets to hold the rollers between the adjacent column parts, and
satisfying a relation
{.theta./(n-1)}.degree.<a.sub.0<90.degree. wherein n
represents the number of rollers housed in the pockets, a.sub.0
represent an angle formed between opposed wall surfaces of the
adjacent column parts, and .theta. represents a center angle formed
between rotation centers of the rollers housed in the pockets
positioned at circumferential both ends.
[0050] When the angle a.sub.0 formed between the opposed wall
surfaces of the adjacent column parts is decreased in the retainer
for the rocking bearing, the number of pockets formed at the same
time in one die is reduced. Therefore, the larger angle a.sub.0 is
desirable in view of molding improvement, and a lower limit value
of the angle a.sub.0 is set to {.theta./(n-1)}.degree.
[0051] Meanwhile, when the angle a.sub.0 is increased, the roller
could not be appropriately held by the pocket. More specifically,
when a.sub.0.gtoreq.90.degree., component force F.sub.1 acting in a
parallel direction to the wall surface and component force F.sub.2
acting in a vertical direction to the wall surface of the force
pressing the wall surface of the column part by the roller have a
relation: F.sub.1.gtoreq.F.sub.2. In this case, the roller could be
brought on the column part and in contact with the adjacent roller.
This causes the oil film cutting and heat generation on the roller
surface. Therefore, the smaller angle a.sub.0 is desirable in view
of appropriate roller retention, so that the upper limit value of
the angle a.sub.0 is set to 90.degree..
[0052] Thus, the rocking bearing can be high in productivity and
load capacity.
[0053] A retainer for a rocking bearing according to the present
invention includes a pair of connection parts extending in a
circumferential direction, and a plurality of column parts
connecting the pair of connection parts to each other to form a
plurality of pockets to hold the rollers between the adjacent
column parts, and satisfies a relation
{.theta./(n-1)}.degree.<a.sub.0<90.degree. wherein n
represents the number of rollers housed in the pockets, a.sub.o
represents an angle formed between opposed wall surfaces of the
adjacent column parts, and .theta. represents a center angle formed
between rotation centers of the rollers housed in the pockets
positioned at circumferential both ends.
[0054] A rocking bearing includes an outer ring for the rocking
bearing containing a raceway surface on the inner diameter side and
having a flange part provided by bending axial each end to the
inner diameter side, a plurality of rollers arranged on the raceway
surface and any one of the retainers for the rocking bearing
described above.
[0055] According to a still another aspect of the present
invention, an air disk brake system includes any one of the rocking
bearing described above.
[0056] Since the above air disk brake system contains the rocking
bearing having preferable assembling properties, its productivity
can be improved.
BRIEF DESCRIPTION OF DRAWINGS
[0057] FIG. 1 is a perspective view showing an outer ring for a
rocking bearing according to one embodiment of the present
invention;
[0058] FIG. 2 is a perspective view showing a retainer contained in
a rocking bearing according to one embodiment of the present
invention;
[0059] FIG. 3 is a perspective view showing the retainer having
rollers in pockets on the lower side;
[0060] FIG. 4 is a perspective view showing the retainer having the
rollers in the pockets on the upper side;
[0061] FIG. 5 is a perspective view showing a rocking bearing
according to one embodiment of the present invention;
[0062] FIG. 6 is a sectional view showing the rocking bearing shown
in FIG. 5 when cut by a plane containing an engagement part;
[0063] FIG. 7 is a sectional view showing the rocking bearing shown
in FIG. 5 viewed in an axial direction;
[0064] FIG. 8 is an enlarged view showing a part VIII in FIG.
7;
[0065] FIG. 9 is a further enlarged view of FIG. 8;
[0066] FIG. 10 is a view showing a retainer for the rocking bearing
according to another embodiment of the present invention;
[0067] FIG. 11 is a sectional view showing a rocking bearing
including an outer ring for the rocking bearing according to
another embodiment of the present invention when cut by a plane
containing an engagement part;
[0068] FIG. 12 is a sectional view showing a rocking bearing
including an outer ring for the rocking bearing according to still
another embodiment of the present invention when cut by a plane
containing an engagement part;
[0069] FIG. 13 is a sectional view showing a state before a roller
and a retainer are assembled in an outer ring for the rocking
bearing;
[0070] FIG. 14 is a sectional view showing a state after the roller
and the retainer have been assembled in the outer ring for the
rocking bearing;
[0071] FIG. 15 is an enlarged view showing a part of a rocking
bearing according to still another embodiment of the present
invention;
[0072] FIG. 16 is a view showing a retainer provided in a rocking
bearing according to still another embodiment of the present
invention;
[0073] FIG. 17 is a sectional view showing a rocking bearing
according to still another embodiment of the present invention;
[0074] FIG. 18 is a sectional view showing a rocking bearing
according to still another embodiment of the present invention;
[0075] FIG. 19 is an enlarged view showing a part of the rocking
bearing shown in FIG. 17;
[0076] FIG. 20 is an enlarged view showing a part of a rocking
bearing according to still another embodiment of the present
invention;
[0077] FIG. 21 is an enlarged view showing a part of a rocking
bearing according to still another embodiment of the present
invention;
[0078] FIG. 22 is an enlarged view showing a part of a rocking
bearing according to still another embodiment of the present
invention;
[0079] FIG. 23 is a view showing a rocking bearing according to
still another embodiment of the present invention taken in an axial
direction when a click part does not abut on a projection part;
[0080] FIG. 24 is a view showing the rocking bearing according to
still another embodiment of the present invention taken in the
axial direction when the click part abuts on the projection
part;
[0081] FIG. 25 is a perspective view showing an outer ring for the
rocking bearing provided in a rocking bearing according to still
another embodiment of the present invention;
[0082] FIG. 26 is a view showing the rocking bearing containing the
outer ring for the rocking bearing shown in FIG. 25 taken in the
axial direction when a click part does not abut on a projection
part;
[0083] FIG. 27 is a view showing the rocking bearing containing the
outer ring for the rocking bearing shown in FIG. 25 taken in the
axial direction when the click part abuts on the projection
part;
[0084] FIG. 28 is a flowchart showing representative production
steps of the outer ring for the rocking bearing;
[0085] FIG. 29 is a view explaining a two-stage heat treatment
method;
[0086] FIG. 30 is a view explaining a variation of the two-stage
heat treatment method;
[0087] FIG. 31 is a view showing microstructure, austenite grains
especially in a bearing component subjected to a heat treatment
pattern shown in FIG. 29;
[0088] FIG. 32 is a view showing microstructure, austenite grains
especially in a conventional bearing component;
[0089] FIG. 33 is a schematic diagram of the microstructure shown
in FIG. 31 in which an illustrated austenite grain boundary is
shown;
[0090] FIG. 34 is a schematic diagram of the microstructure shown
in FIG. 32 in which an illustrated austenite grain boundary is
shown;
[0091] FIG. 35 is a sectional view showing structures (dimensions)
of samples 1 to 6;
[0092] FIG. 36 is a sectional view showing structures (dimensions)
of samples 7 to 11;
[0093] FIG. 37 is a front view showing an essential part of a
peeling life test machine;
[0094] FIG. 38 is a sectional view taken along line XXXVIII-XXXVIII
in FIG. 37;
[0095] FIG. 39 is a schematic sectional view showing a part of an
air disk brake system according to one embodiment of the present
invention; and
[0096] FIG. 40 is a schematic sectional view showing a part of a
conventional air disk brake system.
BEST MODE FOR CARRYING OUT THE INVENTION
[0097] Embodiments of the present invention will be described with
reference to the drawings hereinafter. FIG. 1 is a perspective view
showing an outer ring a the rocking bearing (referred to as the
"outer ring" hereinafter) according to one embodiment of the
present invention. A constitution of an outer ring 11a will be
described with reference to FIG. 1. The outer ring 11a has a
configuration provided by splitting a cylindrical member at two
circumferential certain points. A raceway surface 12 on which
rollers roll is provided on the inner diameter side of the outer
ring 11a.
[0098] Projection parts 14a and 14b extending toward the inner
diameter side are provided at circumferential one end of the outer
ring 11a. Although a retainer arranged on the inner diameter side
of the outer ring 11a can be moved in a circumferential direction,
its circumferential movement is restricted at the one end by the
projection parts 14a and 14b.
[0099] In addition, a tongue-shaped protrusion part 15a bent toward
the outer diameter side is provided between the projection parts
14a and 14b. Meanwhile, a tongue-shaped protrusion part 16a is also
provided at the circumferential other end of the outer ring 11a. By
use of the protrusion parts 15a and 16a, the outer ring 11a is
mounted on a housing (not shown) and fixed so that the
circumferential movement of the outer ring 11a is restricted.
[0100] The outer ring 11a has flange parts 13a and 13b whose axial
both ends are bent toward the inner diameter side. The flange parts
13a and 13b restrict the axial movement of rollers and the retainer
arranged on the inner diameter side of the outer ring 11a.
[0101] Here, the flange parts 13a and 13b have bent parts 17a and
17b bent toward the side of the raceway surface 12a in the axial
direction so as to hold the retainer arranged on the inner diameter
side, respectively. The bent parts 17a and 17b are sequentially
provided so as to be continued in the circumferential
direction.
[0102] Next, a description will be made of a constitution of the
retainer provided in the rocking bearing according to one
embodiment of the present invention and arranged on the inner
diameter side of the outer ring 11a. FIG. 2 is a perspective view
showing the retainer to be arranged on the inner diameter side of
the outer ring 11a. FIGS. 3 and 4 are perspective views showing
states in which rollers 20a are housed in pockets 22a of a retainer
21a shown in FIG. 2. FIG. 3 shows a state in which the rollers 20a
are provided on the lower side, and FIG. 4 shows a state in which
the rollers 20a are provided on the upper side. Referring to FIGS.
1 to 4, the retainer 21a has a configuration provided by splitting
a cylindrical member at two circumferential certain points similar
to the above-described outer ring 11a and follows the configuration
of the outer ring 11a.
[0103] The retainer 21a includes pockets 22a to hold the rollers
20a, and a pair of connection parts 23a and 23b positioned on axial
both sides of the pockets 22a and continued in the circumferential
direction, that is, extending in the circumferential direction.
Each pocket 22a holds the one roller 20a. A distance between the
pocket 22a positioned on the outermost side in the circumferential
direction and each of circumferential ends 25a and 25b of the
retainer 21a is set so as to be larger than a distance between the
pockets 22a. In addition, a rotation member (not shown) contained
in an air disk brake system is arranged on the inner diameter side
of the retainer 21a.
[0104] The pair of connection parts 23a and 23b is connected in the
axial direction by column parts 24a positioned between the pockets
22a and extending in the axial direction. The column part 24a is
provided on the inner diameter side rather than a PCD (Pitch Circle
Diameter) of the roller 20a held in the pocket 22a. Thus, the
number of the rollers 20a that can be held by the retainer 21a can
be increased. In this case, load capacity of the rocking bearing
containing such retainer 21a can be increased. In addition, after
the rocking bearing has been assembled, the raceway surface 12a and
the column part 24a hold the roller 20a so as to sandwich it, to
restrict the radial movement of the roller 20a.
[0105] The pair of connection parts 23a and 23b have engagement
parts 26a to engage with the bent parts 17a and 17b. The engagement
parts 26a project from the connection parts 23a and 23b in the
axial direction. The engagement part 26a is not continued along the
connection parts 23a and 23b in the circumferential direction, but
the plurality of engagement parts 26a are provided at certain
circumferential points of the connection parts 23a and 23b.
[0106] FIG. 5 is a perspective view showing a rocking bearing 30a
according to one embodiment of the present invention. FIG. 6 is a
sectional view showing the rocking bearing 30a shown in FIG. 5 cut
by a plane containing the engagement part. A description will be
made of a constitution of the rocking bearing 30a according to one
embodiment of the present invention with reference to FIGS. 1 to 6.
The rocking bearing 30a includes the outer ring 11a, the plurality
of rollers 20a, and the retainer 21a to retain the rollers 20a. The
rocking bearing 30a is assembled such that the retainer 21a holding
the rollers 20a is arranged on the inner diameter side of the outer
ring 11a.
[0107] Here, at the time of assembling, the retainer 21a is
arranged on the inner diameter side of the outer ring 11 such that
the bent parts 17a and 17b may engage with the engagement parts
26a. In this constitution, the retainer 21a can be held and
enfolded by the bent parts 17a and 17b and the engagement parts 26a
in the outer ring 11a. Thus, even when the retainer 21a comes to be
moved toward the inner diameter side of the outer ring 11a, that
is, toward a direction shown by arrows A in FIGS. 5 and 6, the
engagement parts 26a of the retainer 21a are caught by the bent
parts 17a and 17b, so that the movement of the retainer 21a toward
the inner diameter side can be restricted. Therefore, the rollers
20a and the retainer 21a can be prevented from dropping out of the
outer ring 11a. In this case, since the retainer 21a is held in
such a manner that the bent parts 17a and 17b engage with the
engagement parts 26a, the rollers 20a and the retainer 21a can be
surely prevented from dropping out of the outer ring 11a. In
addition, the rollers 20a and the retainer 21a are not separated
and not shifted from each other. According to the rocking bearing
30a, when it is mounted on the air disk brake system that will be
described below, a mounting defect is hardly generated. In
addition, at the time of assembling, the rollers 20a and the
retainer 21 are assembled as shown in FIG. 4, and then the outer
ring 11a is assembled from the upper side in FIG. 4 to be fit in.
Thus, the assembling operation can be performed easily without
dispersing the rollers 20a.
[0108] Furthermore, since the bent parts 17a and 17b are continued
in the circumferential direction, the bent parts 17a and 17b can
engage with the engagement parts 26a regardless of the
circumferential positions of the engagement parts 26a. Therefore,
the retainer 21a and the rollers 20a are more surely prevented from
dropping off. Here, the engagement part 26a may be continued in the
circumferential direction. In this case, the retainer 21a can be
held by the bent parts 17a and 17b provided so as to be continued
in the circumferential direction over a circumferential wide range.
Therefore, the retainer 21a can be held more stably, and the
rollers 20a and the retainer 21a can be further prevented from
dropping off.
[0109] In addition, the bent parts 17a and 17b may be provided at
circumferential certain points instead of being continued in the
circumferential direction. In this case also, the retainer 21a is
held by the bent parts 17a and 17b, and the rollers 20a and the
retainer 21a can be prevented from dropping off.
[0110] In addition, since the bent parts 17a and 17b are provided
at both flange parts 13a and 13b, the retainer 21a can be held so
as to be enfolded by both flange parts 13a and 13b. Therefore, the
rollers 20a and the retainer 21a can be prevented from dropping off
more surely.
[0111] Here, recently, the rocking bearing employed in the air disk
brake system comes to be strongly required to be miniaturized and
have high load capacity as the air disk brake system is reduced in
size and increased in power. Thus, as a method for increasing the
load capacity of the rocking bearing, a method for increasing a
roller diameter or increasing the number of rollers is generally
used. However, the increase in roller diameter is contrary to the
demand for miniaturization of the rocking bearing.
[0112] Meanwhile, when the retainer is produced with a resin
material by injection molding, a pocket is formed by punching out a
mold toward the radial outer side of the retainer. At this time,
various efforts have been made to improve molding properties such
that the plurality of adjacent pockets are formed at the same time
with one mold. However, when the number of pockets to hold the
rollers is increased, the molding properties are lowered because
the number of molds is increased and the mold becomes large and its
structure becomes complicated. In addition, when the number of
pockets formed at the same time is increased forcedly to punch out
the mold, the retainer could be damaged.
[0113] Therefore, the column part 24a and the like preferably has
the following relations when the column part 24a is provided. FIG.
7 is a sectional view when the rocking bearing 30a is cut by a
plane perpendicular to the axial direction. FIG. 8 is an enlarged
view showing a part VIII in FIG. 7. FIG. 9 is an enlarged view of
FIG. 8.
[0114] Referring to FIGS. 7 and 8, a rotation member 31a is
arranged on the inner diameter side of the rocking bearing 30a.
Here, it is preferable to have relations B.sub.3.ltoreq.B.sub.1 and
B.sub.2<0.98.times.B.sub.4 wherein B.sub.1 represents an inner
diameter of the column part 24a, B.sub.2 represents an outer
diameter thereof, B.sub.3 represents a diameter of the rotation
member 31a, and B.sub.4 represents a pitch circle 32a. In this
constitution, the number of rollers 20a contained in the retainer
21a can be increased. Therefore, the load capacity of the rocking
bearing 30a can be high.
[0115] In addition, referring to FIGS. 7 to 9, a wall surface of
the column part 24a for guiding the rotation of the roller 20a
(referred to as the "guide surface" hereinafter) is a flat surface
(its cross sectional configuration is a straight line). Thus,
dimensions are set to satisfy
{.theta./(n-1)}.degree.<a.sub.1<90.degree. wherein n
represents the number of the rollers 20a housed in the pockets 22a,
a.sub.1 represents an angle formed between opposed wall surfaces of
the adjacent column parts 24a, and .theta. represents a center
angle between rotation centers of the rollers 20a housed in the
pockets 22a positioned at circumferential both ends.
[0116] As the angle a.sub.1 formed between the opposed wall
surfaces (designating the "guide surface") of the adjacent column
parts 24a is decreased, the number of pockets 22a that can be
formed at the same time by the one mold is decreased. Therefore, it
is preferable that the angle a.sub.1 is large in view of the
improvement of the molding properties, so that a lower limit value
of the angle a.sub.1 is set to {.theta./(n-1)}.degree..
[0117] Meanwhile, when the angle a.sub.1 is increased, the roller
20a could not be held appropriately in the pocket 22a. More
specifically, force F applied from the roller 20a to the wall
surface of the column part 24a can be decomposed into force F.sub.1
acting in a parallel direction to the wall surface of the column
part 24a and force F.sub.2 acting in a vertical direction to the
wall surface of the column part 24a. Thus, the forces F.sub.1 and
F.sub.2 have a relation F.sub.1.gtoreq.F.sub.2 when
a.sub.1.gtoreq.90.degree.. In this case, the roller 20a could be
brought on the column part 24a and in contact with the adjacent
roller 20a at the time of rocking. This causes oil film cutting and
heat generation on the surface of the roller 20a. Therefore, in
order to hold the roller 20a appropriately, the angle a.sub.1 is
preferably small and its upper limit value of the angle a.sub.1 is
set to 90.degree..
[0118] In addition, although the retainer contained in the rocking
bearing has the column part on the inner diameter side than the
pitch circle in the above embodiment, the column part may be
provided on the upper side of the pitch circle or on the outer
diameter side of the pitch circle. In addition, the present
invention may be applied to a retainer having no connection
part.
[0119] For example, a description will be made of a retainer 21b
for the rocking bearing (referred to as the "retainer 21b"
hereinafter) according to another embodiment of the present
invention with reference to FIG. 10. In addition, since a basic
constitution of the retainer 21b is the same as that of the
retainer 21a, a description of the common part is omitted and a
different part will be mainly described.
[0120] The retainer 21b has pockets 22b, a pair of connection parts
23a and 23b extending in the circumferential direction, and column
parts 24b connecting the pair of connection parts to each other. In
addition, the column part 24b extends in the radial direction
across a pitch circle 32b. Thus, dimensions are set to satisfy
{.theta./(n-1)}.degree.<a.sub.2<90.degree. wherein n
represents the number of rollers, .theta. represents the center
angle, and a.sub.2 represents an angle formed between opposed wall
surfaces of the adjacent column part 24b.
[0121] Thus, when the angle formed between the opposed wall
surfaces of the adjacent column parts is set within the above
range, the effect of the present invention can be achieved
regardless of the arranged position of the column part.
[0122] In addition, the retainer 21a and the like is preferably
formed of a resin in view of mass productivity. For example, the
retainer 21a is formed of a resin material in which fiber filler
material is contained in polyamide 46 by injection molding. A
specific example of the fiber filler material includes carbon fiber
and glass fiber.
[0123] In addition, a content of the fiber filler material in
polyamide 46 is within a range of 5% to 20% by weight. When the
content of the fiber filler material is less than 5% by weight, it
is difficult to provide strength required for the retainer 21a.
Meanwhile, when it is more than 20% by weight, the fluidity of the
resin material at the time of molding deteriorates. This causes the
problem such as gas burn and filling shortage in molding the
retainer 21a having many pockets 22a and a thin column part.
Furthermore, when a filling pressure is increased in order to solve
the above problem, a burr could be generated. Therefore, it is
preferable that the content of the fiber filler material is within
the above-described range.
[0124] In addition, referring to FIG. 8, dimensions are set to
satisfy the following formula 2 wherein n represents the number of
rollers 20a housed in the pockets 22a, l represents a length of a
part of the pitch circle 32a overlapping with the roller 20a, and L
represents a circumferential length of the pitch circle 32a between
the rotation centers of the rollers 20a housed in the pockets 22a
positioned at circumferential both ends.
0.9 < ( n - 1 ) .times. l L < 1.0 [ Formula 2 ]
##EQU00002##
[0125] The formula 2 shows an occupancy of the rollers 20a on the
circumference of the pitch circle 32a. Referring to the formula 2,
when the occupancy of the rollers 20a is 0.9 or less, the distance
between the adjacent rollers 20a becomes too large, so that
sufficient load capacity cannot be obtained. Meanwhile, when the
distance between the adjacent rollers 20a is small, the rollers 20a
could be in contact with each other at the time of rocking. This
causes oil film cutting and heat generation on the surface of the
roller 20a. Thus, the occupancy of the rollers 20a needs to be less
than 1.0.
[0126] In addition, although the bent parts are provided at both
flange parts and the engagement parts are provided at both
connection parts in the above embodiment, the bent part and the
engagement part engaging with it may be only provided at one flange
part and one connection part, respectively. FIG. 11 is a sectional
view showing a part of a rocking bearing 30c in this case, and
corresponds to FIG. 6. Referring to FIG. 11, a bent part 17d bent
toward a raceway surface 12c in the axial direction is provided
only on the side of one flange part 13d, in an outer ring 11c
contained in the rocking bearing 30c. The other flange part 13c
just projects toward the inner diameter side. An engagement part
26d projecting in the axial direction is provided at one connection
part 23d of a retainer 21c. The other connection part 23c does not
have the engagement part. In this constitution also, the bent part
17d of the outer ring 11e engages with the engagement part 26d of
the retainer 21c, and the retainer 21c can be held so as to be
enfolded. Therefore, rollers 20c and the retainer 21c can be
prevented from dropping out of the outer ring 11c.
[0127] In addition, although the retainer includes the engagement
part in the above embodiment, it may not include the engagement
part. FIG. 12 is a sectional view showing a part of a rocking
bearing 30e in this case and corresponds to FIG. 6. Referring to
FIG. 12, bent parts 17e and 17f bent toward a raceway surface 12e
in the axial direction are provided at both flange parts 13e and
13f in an outer ring 11e contained in the rocking bearing 30e. In
addition, the engagement part projecting in the axial direction is
not provided at both connection parts 23e and 23f of a retainer
21e. In this constitution also, the retainer 21e can be held such
that the connection parts 23e and 23f of the retainer 21e are
enfolded by the bent parts 17e and 17f of the outer ring 11e. Thus,
rollers 20e and the retainer 21e can be prevented from dropping out
of the outer ring 11e. In this case also, the bent part may be
provided only at one of the flange parts.
[0128] Here, although the retainer 21a is held by the bent parts
17a and 17b of the outer ring 11a, a snap fitting allowable
configuration may be provided at the retainer 21a and/or the bent
parts 17a and 17b so that the retainer 21a can be held by the bent
parts 17a and 17b after passing through the bent parts 17a and 17b.
In this case, the snap fitting allowable configuration includes the
engagement parts 26a and 26b as fitting clicks projecting from the
end faces of the connection parts 23a and 23b of the retainer 21a
in the axial direction. The engagement parts 26a and 26b as the
fitting clicks can snap-fit in the bent parts 17a and 17b. In
addition, chamfered parts may be provided at corners of the
engagement parts 26a and 26b on the outer diameter side. In
addition, chamfered parts may be provided at corners of the bent
parts 17a and 17b on the inner diameter side.
[0129] Here, a description will be made of an assembling method of
a rocking bearing 30g. FIG. 13 is a sectional view showing an outer
ring 11g, a roller 20g, and a retainer 21g before assembled. In
addition, FIG. 14 is a sectional view showing the outer ring 11g,
the roller 20g and the retainer 21g after assembled. In addition,
since basic constitutions of the rocking bearing 30g, the outer
ring 11g, the retainer 21g and the like are the same as those of
the rocking bearing 30a and the like, their description will be
omitted. Referring to FIGS. 13 and 14, chamfered parts 28g are
provided at outer-diameter corners of engagement parts 26g and 26h
as the fitting clicks projecting from end faces 27g and 27h of
connection parts 23g and 23h of the retainer 21g. In addition,
chamfered parts 28h are also provided at corners of the bent parts
17g and 17h on the inner diameter side.
[0130] First, the plurality of rollers 20g are put in pockets 22g
of the retainer 21g as shown in FIG. 4. Then, the outer ring 11g is
moved in a direction shown by an arrow A shown in FIG. 13. Thus,
the bent parts 17g and 17h and the engagement parts 26g and 26h
serving as the fitting clicks are elastically deformed in the axial
direction and the retainer 21g passes through the bent parts 17g
and 17h. Then, the bent parts 17g and 17h snap-fit in the
engagement parts 26g and 26h as the fitting clicks, and the
retainer 21g is held by the bent parts 17g and 17h. Thus, the
rocking bearing 30g is assembled. In this case, the retainer 21g in
which the rollers 20g are incorporated may be moved from a
direction opposite to the arrow A.
[0131] Since the retainer 21g is held in the outer ring 11g so as
to be enfolded by the bent parts 17g and 17h, the retainer 21g is
prevented from moving in the direction of the arrow A in FIGS. 13
and 14, so that the retainer 21g does not drop out of the outer
ring 11g. Since this snap fitting uses the elastic deformation of
the bent parts 17g and 17h of the outer ring 11g and the engagement
parts 26g and 26h serving as the fitting clicks of the retainer
21g, strong force is not necessarily applied at the time of
assembling, so that the assembling can be easily performed. In
addition, the outer ring 11g and the retainer 21g can be prevented
from being damaged at the time of assembling. Therefore, the
assembling properties of the rocking bearing 30g can be
improved.
[0132] Since the chamfered parts 28g and 28h are provided at the
corners on the outer diameter side of the engagement parts 26g and
26h as the fitting clicks and at the corners on the inner diameter
side of the bent parts 17g and 17h, respectively, the snap fitting
can be implemented by use of the chamfered parts 28g provided at
the engagement parts 26g and 26h as the fitting clicks and the
chamfered part 28h provided at the bent parts 17g and 17h. Thus,
the snap fitting can be smoothly performed. Therefore, the
assembling properties are further improved. In this case, the
chamfered parts may be provided at the engagement parts 26g and 26h
as the fitting clicks or the bent parts 17g and 17h. In addition,
the chamfered part provided on the outer diameter side of the
engagement parts 26g and 26h as the fitting clicks include not only
a chamfered part provided by scraping off the corner like the
normal chamfered parts but also a chamfered part 28i having a large
sloped surface as shown in FIG. 15.
[0133] Here, it is preferable that the engagement parts 26g and 26h
as the fitting clicks are provided at the circumferential positions
in which the pocket 22g is formed. In the connection parts 23g and
23h, the circumferential positions in which the pocket is provided
are not connected in the axial direction. In other words, the
column part is not provided there. Thus, the retainer 21g can be
easily elastically deformed in the axial direction in the
circumferential positions of the engagement parts 26g and 26h as
the fitting clicks. Therefore, the assembling properties can be
further improved.
[0134] In addition, although the engagement parts as the fitting
clicks are provided at the circumferential same position, in both
connection parts in the above embodiment, as another example, the
circumferential position of the engagement part as the fitting
click provided in one connection part may be different from the
circumferential position of the engagement part as the fitting
click provided in the other connection part.
[0135] FIG. 16 is a view showing a retainer taken from the inner
diameter side in the above case. Referring to FIG. 16, a retainer
21i has the same constitution as that of the above retainer
basically, and includes pockets 22i, a pair of connection parts 23i
and 23j, and column parts 24i. Here, the pair of connection parts
23i and 23j have engagement parts 26i and 26j as fitting clicks
projecting from end faces 27i and 27j in the axial direction,
respectively. Here, the circumferential position of the engagement
part 26i as the fitting click provided in one connection part 23i
is different from the circumferential position of the engagement
part 26j as the fitting click provided in the other connection part
23j.
[0136] Thus, when the snap fitting is performed, the engagement
part 26i as the fitting click provided in the one connection part
23i and the engagement part 26j as the fitting click provided in
the other connection part 23j are not elastically deformed at the
same circumferential position. Therefore, the retainer 21i can be
elastically deformed in the axial direction at the circumferential
different positions of the engagement parts 26i and 26j as the
fitting clicks, so that the assembling properties are further
improved.
[0137] Especially, when the axial projection amount of the
engagement parts 26i and 26j as the fitting clicks is increased to
surely prevent separation of the outer ring and the retainer 21i,
in the case where the engagement parts 26i and 26j as the fitting
clicks are provided at the axial same positions, the elastic
deformation amount of each of the engagement parts 25i and 26j as
fitting clicks is increased at the time of assembling, which could
cause the damage of the engagement parts 26i and 26j as the fitting
clicks. However, according to the above constitution, the
engagement parts 26i and 26j as the fitting clicks can be prevented
from being damaged.
[0138] In addition, although the snap fitting allowable
configuration includes the engagement part as the fitting click
projecting from the end face of the connection part of the retainer
in the above embodiment, as another example, the snap fitting
allowable configuration may be provided at the connection part of
the retainer and have a slit recessed in the radial direction.
[0139] FIG. 17 is a sectional view showing a rocking bearing in
this case and corresponds to FIG. 6. Referring to FIG. 17, a
rocking bearing 30k has the same configuration as that of the above
rocking bearing basically, and includes an outer ring ilk, a roller
20k, and a retainer 21k to hold the roller 20k. Here, a slit 28k
allowing the axial elastic deformation of a connection part 23k is
provided at the one connection part 23k of a pair of connection
parts 23k and 23l of the retainer 21k. The slit 28k is recessed
from an outer diameter surface 29k of the connection part 23k in
the radial direction, that is, toward the inner diameter side so as
to be continued along the connection part 23k. In addition, the
slit 23k has a roughly V-shaped section. Here, the snap fitting
allowable configuration includes the slit 28k. The retainer 21k can
be elastically deformed so that the connection part 23k is shrunk
in the axial direction by use of the slit 28k. Therefore, the
connection part 23k snap-fit in the bent part 17k, whereby the
retainer 21k can be held by the bent part 17k of the outer ring
ilk. Therefore, similar to the above rocking bearing, its
assembling properties can be improved.
[0140] In addition, although the slit 28k is provided only one
connection part 23k in the above embodiment, as another case, slits
28k and 28l may be provided at both connection parts 23k and 23l,
respectively as shown in FIG. 18. In other words, the snap fitting
allowable configuration may include the slits 28k and 28l provided
at the connection parts 23k and 23l, respectively. Furthermore, the
slits 28k and 28l may be partially provided in the circumferential
direction and they may not be necessarily continued in the
circumferential direction.
[0141] Here, it is preferable that dimensions of the slit 28k have
the following relation. FIG. 19 is an enlarged view showing the
slit 28k in the rocking bearing 30k shown in FIG. 17. Referring to
FIG. 19, the dimension are set to have a relation
0.2W.sub.2<W.sub.1<0.8W.sub.2 wherein W.sub.1 represents an
axial length of the of the slit 28k, and W.sub.2 represents an
axial length of the connection part 23k. In addition, the dimension
are set to have a relation 0.2H.sub.2<H.sub.1<0.8H.sub.2
wherein H.sub.1 represents a radial length of the slit 28k, and
H.sub.2 represents a radial length of the connection part 23k.
Here, the axial length W.sub.1 of the slit 28k designates a length
of the slit 28k on the side of the outer diameter surface 29k, and
the length W.sub.2 of the connection part 23k designates an axial
length from an end face 27k of the connection part 23k to a wall
surface 21 of the pocket. In addition, the radial length H.sub.1 of
the slit 28k designates a length from the outer diameter surface
29k to a radial most recessed part of the slit 28k, and the radial
length H.sub.2 of the connection part 23k designates a length from
the outer diameter surface 29k to an inner diameter surface 29l of
the connection part 23k.
[0142] Thus, the connection part 23k can be appropriately
elastically deformed. That is, when 0.2W.sub.2<W.sub.1 and
0.2H.sub.2<H.sub.1, the connection part 23k can be elastically
deformed and the snap fitting can be implemented appropriately. In
addition, when W.sub.1<0.8W.sub.2 and H.sub.1<0.8H.sub.2, the
connection part 23k can be prevented from being damaged at the time
of snap fitting.
[0143] In addition, although the slit has the roughly V-shaped
section in the above embodiment, it may have another configuration.
FIG. 20 is an enlarged sectional view showing a part of a rocking
bearing in this case, and corresponds to FIG. 19. Referring to FIG.
20, a rocking bearing 30m has the same constitution as that of the
above rocking bearing basically, and includes an outer ring 11m, a
roller 20m, and a retainer 21m holding the roller 20m. A connection
part 23m of the retainer 21m is provided with a slit 28m. Side wall
surfaces 25m and 25n of the slit 28m are roughly parallel to an end
face 27m of the connection part 23m, and a bottom part 26m recessed
toward the inner diameter side has R section. The slit may be the
slit 28m having the above configuration.
[0144] Similar to the above, the dimensions have a relation
0.2W.sub.2<W.sub.1<0.8W.sub.2 wherein W.sub.1 represents an
axial length of the slit 28m, and W.sub.2 represents an axial
length of the connection part 23m. In addition, dimensions have a
relation 0.2H.sub.2<H.sub.1<0.8H.sub.2 wherein H.sub.1
represents a radial length of the slit 28m, and H.sub.2 represents
a radial length of the connection part 23m. Thus, similar to the
rocking bearing shown in FIGS. 17 to 19, the connection part 23m
can be appropriately elastically deformed. Here, the axial length
W.sub.1 of the slit 28m designates a length between the side wall
surfaces 25m and 25n of the slit 28m, and the length W.sub.2 of the
connection part 23m designates an axial length from an end face 27m
of the connection part 23m to a wall surface 27n of a pocket. In
addition, the radial length H.sub.1 of the slit 28m designates a
length from the outer diameter surface 29m to a bottom part 26m,
and the radial length H.sub.2 of the connection part 23m designates
a length from the outer diameter surface 29m to an inner diameter
surface 29n of the connection part 23m.
[0145] In addition, in this case also, the slit having the same
configuration may be provided at each connection part. In addition,
the present invention is not limited to the configurations shown in
FIGS. 17 to 20, and may be applied to other various
configurations.
[0146] Furthermore, as shown in FIG. 21, the snap fitting allowable
configuration may include an end face 28p of a connection part 23p
sloped so that its axial length is increased from the outer
diameter side to the inner diameter side in a retainer 21p
contained in a rocking bearing 30p. In this case also, the
connection part 23p can snap-fit in the bent part 17p.
[0147] Here, for example, the above snap fitting allowable
configurations may be combined such that the slit is provided at
one connection part and the fitting click is provided at the other
connection part in the retainer. In this case, for example, when
the slit recessed from the inner diameter surface toward the outer
diameter side is provided at the connection part having the end
face 28p shown in FIG. 21, the snap fitting can be more easily
implemented.
[0148] In addition, as shown in FIG. 22, the snap fitting allowable
configuration may be provided in a bent part 17q. The bent part 17q
provided at the flange part of an outer ring 11q in a rocking
bearing 30q is folded back in the axial direction. In this case,
the snap fitting can be implemented between the bent part 17q and
the connection part 23q by elastically deforming the bent part 17q
in the axial direction.
[0149] In addition, as the retainer arranged on the inner diameter
side of the outer ring can be circumferentially moved in the above
rocking bearing, it is necessary to provide movement restricting
means in order to prevent the retainer from dropping out of the
outer ring. According to a conventional example, a projection part
projecting toward the inner diameter side is provided at a
circumferential end of an outer ring and the projection part abuts
on a circumferential end of a retainer to restrict the
circumferential movement of the retainer. However, according to the
movement restricting means, the circumferential movable range of
the retainer cannot be provided enough. Meanwhile, according to
Japanese Unexamined Patent Publication No. 2003-214330, a control
lever is provided in a rocking bearing as a new member, a raceway
ring and a retainer are connected so as not to be separated, and
both ends of the control lever are fit in a rotation member and a
fix member, to restrict the circumferential movement of the
retainer. However, according to the Japanese Unexamined Patent
Publication No. 2003-214330, since it is necessary to provide the
control lever, this is not preferable in view of the aim to reduce
cost and the number of components.
[0150] Here, for example, in the rocking bearing 30a containing the
outer ring 11a shown in FIG. 1, a click part to abut on and engage
with a projection part provided in a retainer that will be
described later in the circumferential direction may be provided at
axial both ends of the outer ring 11a in which the flange parts 13a
and 13b are not provided. In addition, the projection parts may be
provided at predetermined positions of axial end faces 27a and 27b
of the connection parts 23a and 23b.
[0151] The above will be described with reference to FIGS. 23 and
24. FIGS. 23 and 24 are views showing the rocking bearing 30a taken
from the axial direction, in which FIG. 23 shows a state in which a
click part 18a does not abut on a projection part 18b, and FIG. 24
shows a state in which the click part 18a abuts on the projection
part 18b. In addition, the flange parts 13a and 13b are not shown
in FIGS. 23 and 24 in view of easy understanding In addition, since
the basic constitutions of the rocking bearing 30a, the outer ring
11a, the retainer 21a are the same as those described above, their
description will be omitted.
[0152] Referring to FIGS. 23, 24, and 1, the click part 18a is
provided at the end opposite to the circumferential end in which
the projection parts 14a and 14b are provided. In addition, the
click part 18a may be provided at the position closer to the end in
the flange parts 13a and 13b. The projection part 18b is provided
at the position closer to the end 25a of the ends 25a and 25b. In
addition, the projection part 18b is provided circumferential
peripheral inner side than the pocket 22a arranged circumferential
outermost side. In addition, although the projection part 18b is
combined with the engagement part 26a here, the projection part 18b
and the engagement part 26a may be provided separately.
[0153] The retainer 21a is moved within a predetermined range in
the circumferential direction in the outer ring 11a. The retainer
21a is moved around a rotation center 33a in the circumferential
direction, that is, a direction shown by an arrow E in FIG. 23 and
its opposite direction. Here, when the retainer 21a is moved in the
circumferential direction, and the projection part 18b provided at
the predetermined position of the connection part 23a, 23b abuts on
the click part 18a provided in the outer ring 11a, the retainer 21a
cannot be moved in the circumferential direction any more.
[0154] Thus, the circumferential movement of the retainer 21a can
be restricted. In other words, after the retainer 21a is
circumferentially moved in the outer ring 11a by the predetermined
amount, the click part 18a abuts on the projection part 18b to
limit the movement amount of the retainer 21a. According to the
rocking bearing 30a having the above constitution, the
circumferential movement amount of the retainer 21a can be
optionally determined by the position of the projection part 18b.
In this case, since the retainer 21a can be moved until the
projection part 18b abuts on the click part 18a, its movement range
can be largely provided. In addition, according to the rocking
bearing 30a containing the outer ring 11a and the retainer 21a,
since it is not likely that the retainer 21a drops off, its
assembling properties is improved. According to the rocking bearing
30a, since it is not necessary to provide a new member, its cost
can be low.
[0155] In addition, since the predetermined position of the
projection part 18b is on the circumferential inner side than the
pocket 22a arranged in the circumferential outermost side, and the
movement of the retainer 21a is limited at the position in which a
part of the retainer 21a projects from the circumferential one end
of the outer ring 11a, the movement range of the retainer 21a can
be further increased within a rolling range of the roller 20a held
in the pocket 22a.
[0156] The circumferential length of the retainer 21a projecting
from the outer ring 11a may be not more than the circumferential
length from the one end 25a of the retainer 21a to the pocket 22a
positioned on the circumferential outermost side on the one end 25a
side. More specifically, a length F is to be not more than a length
G in FIGS. 23 and 24. Thus, the movement range of the retainer 21a
can be further increased. In addition, even when the projection
part 18b abuts on the click part 18a, the roller 20a housed in the
pocket 22a positioned on the circumferential outermost side does
not drop off. Therefore, the roller 20a housed in the pocket 22a
arranged on the circumferential outermost side can be prevented
from dropping off. According to such rocking bearing 30a, its
assembling properties can be further improved.
[0157] In addition, the predetermined position of the projection
part 18b may be on the circumferential outer side than the pocket
22a provided on the outermost side on the side of the engagement
part end 25a. In this case also, the movement range of the retainer
21a can be largely provided.
[0158] In addition, the click part 18a and the projection part 18b
abutting thereon may be provided only axial one side. In this case
also, the circumferential movement of the retainer 21a can be
restricted.
[0159] Here, although the click part is provided at the
circumferential end of the outer ring in the above embodiment, the
click part may be provided at a predetermined position close to the
circumferential end of the outer ring. FIGS. 25, 26, and 27 show an
outer ring and a rocking bearing in this case, and correspond to
FIGS. 1, 23, and 24, respectively. Referring to FIGS. 25 to 27, a
constitution of an outer ring 11r is basically the same as that of
the outer ring 11a shown in FIG. 1, and the outer ring 11r has a
raceway surface 12r, flange parts 13r and 13s, projection parts 14r
and 14s, protrusions 15r and 16r, and bent parts 17r and 17s. A
retainer 21r is circumferentially moved around a rotation center
33r. Here, a click part 18r is provided at a predetermined position
close to its circumferential end. In addition, the click part 18r
is provided on the side of the raceway surface 12r of the flange
parts 13r and 13s. In this case also, the movement range of the
retainer 21r can be largely provided.
[0160] The above outer ring is produced by the following production
method. As a starting material, carbon steel containing 0.5 to 1.1%
by weight of carbon is used. More specifically, SK5, SUJ2, and
SAE1070 containing 0.5 to 1.1% by weight of carbon (all of them
comply with JIS) may be used.
[0161] FIG. 28 is a flowchart showing representative production
steps of the outer ring. Referring to FIG. 28, a steel plate of the
above starting material is punched out (FIG. 28(A)). Then, the
flange part is formed by a bending process, whereby an outline
configuration of the outer ring is formed (FIG. 28(B)). This
bending step is implemented by a pressing process. In this case,
since the above material having the above carbon content is used,
that is, since the material containing 1.1% or less by weight of
carbon is used, its processability is preferable, so that the
outline configuration of the outer ring can be formed with high
accuracy. In addition, since the bending process is performed by
the pressing process, the outline configuration of the outer ring
can be formed at low cost.
[0162] Then, a heat treatment is performed (FIG. 28(C)). Here, a
bright quenching treatment or high-frequency quenching treatment is
performed as the heat treatment. In this case, since the material
containing 0.5% or more of carbon is used, hardness required for
the outer ring, that is, hardness of Hv653 or more can be provided
by the bright quenching treatment or the high-frequency quenching
treatment. Accordingly, a carburized quenching treatment is not
needed. Therefore, the outer ring is not likely to be prevented
from being deformed and the outline configuration of the outer ring
can be maintained with high accuracy.
[0163] Here, the bright quenching treatment means a quenching
treatment in which the steel is heated in a protective atmosphere
or vacuum while its surface is prevented from being oxidized. This
quenching treatment is low in facility cost. Therefore, the
production cost can be low.
[0164] The high-frequency quenching treatment is a method for
producing a hardened layer by heating a steel surface rapidly by
use of induction heating and then cooling rapidly. This quenching
treatment is also low in facility cost. Therefore, production cost
can be also low. In addition, since a gas is not needed in the heat
treatment step, it has an advantage of being environment-friendly.
Furthermore, the quenching treatment can be partially
performed.
[0165] Furthermore, it is preferable to perform a tempering
treatment after the above quenching treatment to reduce a residual
stress and internal distortion generated in the quenching
treatment, and to improve the toughness and stabilize the
dimension.
[0166] In addition, after the heat treatment, a polishing process
for polishing the object is performed and then a cleaning process
is performed, whereby a final product is provided. In addition, the
rollers and the retainer are assembled in the above outer ring
produced as described above, whereby the rocking bearing is
completed.
[0167] As described above, the outline configuration can be formed
by the pressing process with high accuracy. In addition, the
hardness required for the outer ring can be provided by the bright
quenching treatment or the high-frequency quenching treatment as
the heat treatment. Thus, the deformation can be prevented at the
time of heat treatment. Therefore, the outer ring is high in
accuracy, low in cost, and high in load capacity. Furthermore,
since not only the raceway surface but also the bent part can be
high in hardness, the bent part is prevented from being damaged.
Therefore, the retainer and the roller can be more surely prevented
from dropping off.
[0168] In addition, the above outer ring may be produced by the
following production method. As a starting material, carbon steel
containing 0.15% to 1.1% by weight of carbon is used. More
specifically, SCM415 and S50C containing 0.15% to 0.5% by weight of
carbon (both comply with JIS) or SAE1070 and SK5 containing 0.5% to
1.1% by weight of carbon (both comply with JIS) may be used.
[0169] Referring to FIG. 28 again, the steel plate of the starting
material is punched out (FIG. 28(A)). Then, the flange part is bent
by the bending process, whereby the outline of the outer ring is
formed (FIG. 28(B)). Then, the above heat treatment is performed
(FIG. 28(C)). Then, the polishing process is performed and the
cleaning process is performed, whereby the final product is
completed.
[0170] Here, as the heat treatment, carbonitriding treatment is
performed. When the carbonitriding treatment is performed on the
material containing 0.15 to 1.1% by weight of carbon, the outer
ring having the required hardness can be produced at low cost. That
is, since the outer ring has high load capacity, it is hardly
damaged. In addition, since the strength of the bent part can be
high, the retainer and the roller can be more surely prevented from
dropping off.
[0171] As another heat treatment, a carburizing treatment may be
performed. The carburizing treatment is a heat treatment using a
phenomenon in which carbon is soluble in high-temperature steel, by
which while the carbon content is low inside the steel, the carbon
content is high in a surface layer (hardened layer). Thus, the
carburized material has a hard surface but its inside is soft and
high in toughness. In addition, according to such quenching
treatment, its facility cost is low.
[0172] Furthermore, it is preferable to perform a tempering
treatment after the above quenching treatment to reduce the
residual stress and internal distortion generated in the quenching
treatment, and to improve the toughness and stabilize the
dimension.
[0173] In addition, the outer ring and/or the roller may have a
nitrogen enrichment layer, and an austenite grain size number of 10
or more, and contains 11% to 25% by volume of retained austenite
and 0.1% to 0.7% by weight of nitrogen. In this constitution, the
rocking bearing features a long life.
[0174] When a low-temperature secondary quenching treatment as the
heat treatment to be described below is performed on the outer ring
and/or the roller in the rocking bearing, the outer ring and/or the
roller can have an austenite grain size number in the nitrogen
enrichment layer that exceeds 10, and contains 11% to 25% by volume
of retained austenite and 0.1% to 0.7% by weight of nitrogen.
[0175] Next, a description will be made of the heat treatment
including the carbonitriding treatment performed on the outer ring
and/or the roller. In addition, a roller bearing having a roller
(outer ring), a roller shaft (inner ring), and rollers as bearing
components, is used in a working example. FIG. 29 is a view showing
one example of a two-stage heat treatment to obtain the above
bearing components. In addition, FIG. 30 is a view showing a
variation of the two-stage heat treatment shown in FIG. 29. Thus,
FIG. 29 shows a heat treatment pattern in which a primary quenching
treatment and a secondary quenching treatment are performed, and
FIG. 30 shows a heat treatment pattern in which a material is
cooled below the transformation temperature of A.sub.1 during the
quenching treatment and then heated again to be quenched at a final
stage. In either case, the above bearing components can be
produced. In these drawings, carbon and nitrogen are diffused and
carbon is sufficiently dissolved in a steel base in a treatment
T.sub.1, and then the steel base is cooled below the transformation
temperature A.sub.1. Then, in a treatment T.sub.2, the steel is
heated again to the temperature lower than that in the treatment
T.sub.1, and then subjected to an oil quenching treatment. In
addition, the heat treatment methods shown in FIGS. 29 and 30 are
called the two-stage heat treatment collectively.
[0176] According to the above heat treatment, while the surface
layer is carbonitrided, cracking strength can be improved and an
aging length change rate can be reduced as compared with the
general quenching treatment in which the quenching treatment is
performed one time after the carbonitriding treatment. Through the
above heat treatment method, a microstructure in which the
austenite grain size can be less than half the conventional one can
be provided. According to the bearing component subjected to the
above heat treatment, rolling fatigue characteristics has a long
life, the cracking strength is improved and the aging length change
rate can be reduced.
[0177] FIGS. 31 and 32 show the microstructures of the austenite
grains of the bearing components. FIG. 31 shows a bearing component
subjected to the above heat treatment, and FIG. 32 shows a
conventional bearing component. More specifically, FIG. 31 shows
the austenite grain size of bearing steel subjected to the heat
treatment pattern shown in FIG. 30. In addition, for comparison,
FIG. 32 shows the austenite grain size of the bearing steel
subjected to a conventional heat treatment method. In addition,
FIGS. 33 and 34 are views showing illustrated austenite grain
boundaries of FIGS. 31 and 32, respectively. According to the
structure of the austenite grain size, the austenite grain size
number according to JIS standard is 10 or less in the case of the
conventional treatment, and the number is 12 in the case of the
above two-stage heat treatment. In addition, an average grain size
in FIG. 31 measured by a section method is 5.6 .mu.m.
[0178] The working example will be described hereinafter. A roll, a
roll shaft, and a roller were produced by the three kinds of heat
treatments such as a standard heat treatment, a carbonitriding
treatment, and a two-stage heat treatment. The standard heat
treatment, the carbonitriding treatment, and the two-stage heat
treatment are the following heat treatments.
[0179] The standard heat treatment: After a heat treatment at a
heating temperature of 840.degree. C. for a retention time of 20
minutes in a RX gas atmosphere, a quenching treatment was performed
and then a tempering treatment was performed at 180.degree. C. for
90 minutes.
[0180] Carbonitriding treatment: After a heat treatment at a
heating temperature of 850.degree. C. for a retention time of 150
minutes in a RX-ammonia mixture gas atmosphere, a quenching
treatment was performed from a temperature of 850.degree. C. and
then a tempering treatment was performed at 180.degree. C. for 90
minutes.
[0181] Two-stage heat treatment: A carbonitriding treatment was
performed at a carbonitriding treatment temperature of 850.degree.
C. for a retention time of 150 minutes. The carbonitriding
treatment was performed in a RX-ammonia mixture gas atmosphere.
Then, based on the heat treatment pattern shown in FIG. 29, the
primary quenching was performed at the carbonitriding treatment
temperature of 850.degree. C., and the secondary quenching was
performed at a temperature of 800.degree. C. lower than the
carbonitriding treatment temperature, for 20 minutes, and a
tempering treatment was performed at 180.degree. C. for 90
minutes.
[0182] Table 1 shows qualities of the members provided by the above
heat treatments.
TABLE-US-00001 TABLE 1 RETAINED AUSTENITE AUSTENITE NITROGEN HEAT
TREATMENT GRAIN SIDE VOLUME CONTENT METHOD (JIS) (% BY VOLUME) (%
BY WEIGHT) STANDARD HEAT 9 7 0 TREATMENT CARBONITRIDING 8 29 0.31
TRATMENT TWO-STAGE HEAT 12 21 0.30 TREATMENT
[0183] A description will be made of methods for examining material
qualities.
[0184] Austenite grain size: The austenite grain size was measured
based on an austenite grain size testing method for steel of JIS G
0551.
[0185] Retained austenite volume: The retained austenite volume was
measured by comparing the diffraction intensity of martensite
.alpha. (211) with that of retained austenite .gamma. (220). As the
retained austenite volume, the value at a surface layer of 50 .mu.m
from a rolling surface after ground was used.
[0186] Nitrogen content: The nitrogen content was measured by use
of EPMA. As the nitrogen content, a value at a surface layer of 50
.mu.m from the rolling surface after ground was used.
[0187] Next, the test result shown in Table 1 will be
described.
[0188] Austenite grain size: The grain size number of the member
through the two-stage heat treatment is as fine as 12, which is
considerably miniaturized. The grain size numbers of the member
through the standard heat treatment and the member through the
carbonitriding treatment are 9 and 8, respectively and the
austenite grains are larger than that of the member through the
two-stage heat treatment.
[0189] Retained austenite volume: The retained austenite volume of
the member through the two-stage heat treatment is 21% by volume
and austenite exists appropriately. Meanwhile, the retained
austenite volume of the member through the standard heat treatment
is 7% by volume which is less than that of the member through the
two-stage heat treatment. In addition, the retained austenite
volume of the member through the carbonitriding treatment is 29% by
volume which is more than that of the member through the two-stage
heat treatment. As a result, it can be understood that the member
through the two-stage heat treatment is intermediate in retained
austenite volume between the member through the standard heat
treatment and the member through the carbonitriding treatment.
[0190] Nitrogen content: The nitrogen content of the member through
the two-stage heat treatment is 0.30%. The nitrogen content of the
member through the standard heat treatment is 0% because the
carbonitriding treatment is not performed. In addition, the
nitrogen content of the member through the carbonitriding treatment
is 0.31%. The nitrogen content of the member through the two-stage
heat treatment is a little less than that of the member through the
carbonitriding treatment. This is attributed to the fact that the
secondary quenching treatment was performed at 800.degree. C. lower
than the carbonitriding treatment temperature after the
carbonitriding treatment in the two-stage heat treatment.
[0191] Then, roller bearings are made up of various combinations of
the roll, the roll shaft, and the rollers produced by the above
three kinds of heat treatments, as samples 1 to 11. FIG. 35 is a
sectional view showing the structures (dimensions) of the samples 1
to 6. FIG. 36 is a sectional view showing the structures
(dimensions) of the samples 7 to 11. As shown in FIG. 35, according
to the samples 1 to 6, a roll 62 and roller 64 are 6.9 mm in width,
and a roll shaft 63 is 17.3 mm in width. Meanwhile, as shown in
FIG. 36, according to the samples 7 to 11, the roll 62 and the
roller 64 are 5.5 mm in width, and the roll shaft 63 is 15.9 mm in
width. That is, the samples 7 to 11 are reduced in size by about
20% as compared with the samples 1 to 6.
[0192] Then, a peeling life test was performed on the samples 1 to
11 by the following method. FIG. 37 is a front view showing an
essential part of a peeling life test machine 65, and FIG. 38 is a
sectional view taken along a line XXXVIII-XXXVIII in FIG. 37. As
shown in FIGS. 37 and 38, a roller bearing 61 is arranged so that a
driving roll 66 of the peeling life test machine 65 is brought in
contact with the roll 62 to fix the roller shaft 63. Thus, under
the condition that a radial load was applied from the driving roll
66 of the peeling life test machine 65, the driving roll 66 was
rotated in a direction shown by an arrow in FIG. 37 to rotate the
roll 62. A time (life) to occurrence of peeling in any one of the
roll 62, the roll shaft 63, and the roller 64 was measured. In
addition, the load applied from the driving roll 66 to the roller
bearing 61 was set to 2.58 kN, and the rotation speed of the roll
62 was set to 7000 r/min. In addition, as lubricant oil between the
roller 64, and the roll 62 and the roll shaft 63, 10W-30 engine oil
was used and the temperature of the lubricant oil was set to
100.degree. C.
[0193] Tables 2 and 3 show the combinations of the members of the
samples and the peeling lives of the samples. The samples 6, 9 10
and 11 were subjected to the two-stage heat treatment. In addition,
the peeling lives of the samples are shown assuming that the
peeling life of the sample 1 is set to 1.
TABLE-US-00002 TABLE 2 SAMPLE NO. 1 2 3 4 5 6 SAMPLE 6.9 (mm) WIDTH
OUTER RING STANDRAD HEAT CARBONITRIDING STANDRAD TWO-STAGE (ROLL)
TREATMENT TREATMENT HEAT HEAT TREATMENT TREATMENT ROLLER STANDRAD
CARBONITRIDING TREATMENT TWO-STAGE HEAT (ROLLING HEAT TREATMENT
BODY) TREATMENT INNER RING STANDRAD HEAT CARBONITRIDING TWO-STAGE
HEAT (ROLL TREATMENT TREATMENT TREATMENT SHAFT) LOAD 2.58 (kN)
DAMAGED SHAFT AND SHAFT SHAFT SHAFT SHAFT SHAFT MEMBER ROLLER
PEELING 1 1.3 1.7 1.9 2.8 3.5 LIFE
TABLE-US-00003 TABLE 3 SAMPLE NO. 7 8 9 10 11 SAMPLE 5.5 (mm) WIDTH
OUTER RING STANDRAD CARBONITRIDING TREATMENT (ROLL) HEAT TREATMENT
ROLLER CARBONITRIDING TWO-STAGE CARBONITRIDING TWO-STAGE (ROLLING
TREATMENT HEAT TREATMENT HEAT BODY) TREATMENT TREATMENT INNER RING
CARBONITRIDING TREATMENT TWO-STAGE HEAT TREATMENT (ROLL SHAFT) LOAD
2.58 (kN) DAMAGED OUTER RING SHAFT SHAFT SHAFT SHAFT MEMBER PEELING
LIFE 0.8 1.1 1.2 1.5 1.7
[0194] As shown in Table 2, according to the sample 6 in which all
of the roll 62, the roll shaft 63, and the roller 64 were subjected
to the two-stage heat treatment, the peeling life is 3.5 times as
long as the sample 1 in which all of the members were subjected to
the standard heat treatment. In addition, as shown in Table 3, even
when the bearing is reduced in size, the sample 9 in which the roll
62 and the roll shaft 63 were subjected to the carbonitriding
treatment and the roller 64 was subjected to the two-stage heat
treatment has a peeling life that is 1.2 times as long as the
sample 1. In addition, the sample 10 in which the roll 62 and the
roller 64 were subjected to the carbonitriding treatment, and the
roll shaft 63 was subjected to the two-stage heat treatment has a
peeling life that is 1.5 times as long as the sample 1.
Furthermore, the sample 11 in which the roll 62 was subjected to
the carbonitriding treatment, and the roller 64 and the roll shaft
63 were subjected to the two-stage heat treatment has a peeling
life that is 1.7 times as long as the sample 1. As a result, it can
be understood that each of the roll 62, the roll shaft 63, and the
roller 64 has the nitrogen enrichment layer, and when the roll 62
and/or the roller 64 are subjected to the two-stage heat treatment,
the life can be elongated while the bearing can be reduced in
size.
[0195] Therefore, the rocking bearing composed of the outer ring
and the roller having the same constitutions as above has a longer
peeling life. Therefore, the long life can be achieved.
[0196] Next, a brief description will be made of a constitution of
the air disk brake system having the above-described rocking
bearing. FIG. 39 is a schematic sectional view showing a part of
the air disk brake system according to one embodiment of the
present invention. Referring to FIG. 39, an air disk brake system
71 includes a brake cylinder 79 having an actuator rod 72, a lever
73 connected to one end of the actuator rod 72, a rotation member
74 connected to the other end of the lever 73, a rocking bearing 75
rotatably supporting the rotation member 74, a connection part 80
provided at an eccentric position with respect to the rotation
member 74, a transmission part 76 having one end connected to the
connection part 80, right and left brake pads 77a and 77b working
with the transmission part 76, and a rotor 78 arranged between the
right and left brake pads 77a and 77b.
[0197] The actuator rod 72 pushes the lever 73 in a direction shown
by an arrow C in FIG. 39 by the action of compressed air in the
brake cylinder 79. Thus, the rotation member 74 is rotated and the
transmission part 76 connected to the connection part 80 is pressed
in a direction shown by an arrow D in FIG. 39. Then, when the
transmission part 76 is moved, the right and left brake pads 77a
and 77b sandwich the rotor 78. In addition, when the load from the
rotation member 74 is removed, the transmission part 76 receives
force applied from a spring 81 in a direction opposite to the
direction shown by the arrow D, and the transmission part 76 is
returned to the original position. Thus, the brake pads 77a and 77b
release the rotor 78. Thus, the air disk brake system 71 are
constituted.
[0198] Here, the rocking bearing 75 rotatably supporting the
rotation member 74 has the same constitution as the above shown in
FIG. 5. According the rocking bearing 75, after assembled by
arranging a retainer holding rollers, on the inner diameter side of
an outer ring, the retainer is held so as to be enfolded by a bent
part, so that the roller and the retainer can be prevented from
dropping out of the outer ring. In addition, at the time of
assembling, the roller and the retainer can be prevented from being
separated and shifted. Therefore, the assembling properties of the
rocking bearing 75 are improved.
[0199] Since the air disk brake system 71 contains the rocking
bearing 75 having preferable assembling properties, its
productivity can be improved.
[0200] Furthermore, the air disk brake system 71 may have any one
of the above-described rocking bearings.
[0201] In addition, although the outer ring is formed into the
final outline configuration by punching out the steel plate in the
above embodiments, it may be produced by a cutting process.
[0202] Although the embodiments of the present invention have been
described with reference to the drawings in the above, the present
invention is not limited to the above-illustrated embodiments.
Various kinds of modifications and variations may be added to the
illustrated embodiments within the same or equal scope of the
present invention.
INDUSTRIAL APPLICABILITY
[0203] The outer ring according to the present invention can be
effectively used in the rocking bearing requiring preferable
assembling properties.
[0204] The rocking bearing according to the present invention can
be effectively used when preferable assembling properties are
required.
[0205] The air disk brake system according to the present invention
can be effectively used when productivity is required to be
improved.
* * * * *