U.S. patent application number 12/450435 was filed with the patent office on 2010-03-11 for method of producing outer ring of self- alinging bearing.
Invention is credited to Takehiro Adachi, Yoshikazu Kurashita.
Application Number | 20100058593 12/450435 |
Document ID | / |
Family ID | 39830869 |
Filed Date | 2010-03-11 |
United States Patent
Application |
20100058593 |
Kind Code |
A1 |
Kurashita; Yoshikazu ; et
al. |
March 11, 2010 |
METHOD OF PRODUCING OUTER RING OF SELF- ALINGING BEARING
Abstract
To provide a method of producing an outer ring of a
self-aligning bearing in which at a raceway-turning step after a
heat treatment, the chipping of a turning tool and damage of a
raceway can be prevented. Before the heat treatment, an annular
groove 2b is formed in that portion of the raceway 2a of the outer
ring 2 corresponding to lubrication holes 7, thereby avoiding a
situation in which a discontinuous cutting operation occurs because
of the lubrication holes 7 at the raceway-turning step after the
heat treatment.
Inventors: |
Kurashita; Yoshikazu;
(Osaka, JP) ; Adachi; Takehiro; (Osaka,
JP) |
Correspondence
Address: |
MCGINN INTELLECTUAL PROPERTY LAW GROUP, PLLC
8321 OLD COURTHOUSE ROAD, SUITE 200
VIENNA
VA
22182-3817
US
|
Family ID: |
39830869 |
Appl. No.: |
12/450435 |
Filed: |
March 27, 2008 |
PCT Filed: |
March 27, 2008 |
PCT NO: |
PCT/JP2008/055965 |
371 Date: |
September 25, 2009 |
Current U.S.
Class: |
29/898.13 |
Current CPC
Class: |
Y10T 29/49707 20150115;
F16C 19/38 20130101; B23P 15/003 20130101; F16C 23/086 20130101;
F16C 33/64 20130101 |
Class at
Publication: |
29/898.13 |
International
Class: |
B21D 53/10 20060101
B21D053/10 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 29, 2007 |
JP |
2007-087268 |
Claims
1. A method of producing an outer ring of a self-aligning bearing,
comprising: a first turning step of turning an annular stock to
form a blank having a predetermined machining allowance formed at a
raceway; a boring step of forming lubrication holes in said blank
which lubrication holes are open to the raceway and an outer
periphery of the blank; a heat treatment step of hardening the
blank, having said lubrication holes formed therein, to
predetermined hardness; and a second turning step of turning said
raceway after the heat treatment step; characterized in that:
before said heat treatment step, a turning operation is applied to
that portion of said raceway corresponding to the lubrication holes
to form an annular groove for avoiding a situation in which a
discontinuous cutting operation occurs at said second turning step
because of said lubrication holes.
2. A method of producing an outer ring of a self-aligning bearing,
comprising: a first turning step of turning an annular stock to
form a blank having a predetermined machining allowance formed at a
raceway; a boring step of forming lubrication holes in said blank
which lubrication holes are open to the raceway and an outer
periphery of the blank; a heat treatment step of hardening the
blank, having said lubrication holes formed therein, to
predetermined hardness; a second turning step of turning said
raceway after the heat treatment step while leaving a grinding
allowance; and a grinding step of grinding the raceway for
finishing purposes after the second turning step; characterized in
that: before said heat treatment step, a turning operation is
applied to that portion of said raceway corresponding to the
lubrication holes to form an annular groove for avoiding a
situation in which a discontinuous cutting operation and a
discontinuous grinding operation occur respectively at said second
turning step and said grinding step because of said lubrication
holes.
3. A method of producing an outer ring of a self-aligning bearing,
comprising: a turning step of turning an annular stock to form a
blank having a predetermined grinding allowance formed at a
raceway; a boring step of forming lubrication holes in said blank
which lubrication holes are open to the raceway and an outer
periphery of the blank; a heat treatment step of hardening the
blank, having said lubrication holes formed therein, to
predetermined hardness; and a grinding step of grinding the raceway
for finishing purposes after the heat treatment step; characterized
in that: before said heat treatment step, a turning operation is
applied to that portion of said raceway corresponding to the
lubrication holes to form an annular groove for avoiding a
situation in which a discontinuous grinding operation occurs at
said grinding step because of said lubrication holes.
Description
TECHNICAL FIELD
[0001] The present invention relates to a method of producing an
outer ring of a self-aligning bearing.
BACKGROUND ART
[0002] Self-aligning roller bearings are sometimes used for
supporting a main shaft of a wind turbine generator, a roll in a
continuous casting facility and for other purposes. As a
conventional self-aligning roller bearing, there is known one as
shown in FIG. 7, in which an outer ring 102 and an inner ring 103
are disposed coaxially with each other, and a plurality of rolling
elements 104 comprising respective convex rollers are interposed
between the outer ring 102 and the inner ring 103. A spherical
outer raceway 102a is formed on an inner periphery of the outer
ring 102, and an inner raceway 103a is formed on an outer periphery
of the inner ring 103, and the rolling elements 104 held by cages
105 are rollably arranged in a double-row manner between the
raceways 102a and 103a. Further, an annular lubrication groove 106
is formed in an axially-central portion of the outer periphery of
the outer ring 102, and a plurality of lubrication holes 107 for
supplying lubricating oil to the interior of the bearing are formed
inwardly of the lubrication groove (see, for example, Patent
Literature 1).
[0003] In a method of producing the outer ring 102 of the above
self-aligning roller bearing 101, for example, a first turning step
110 of applying a turning operation to an annular stock formed by
hot forging or the like to thereby form a blank having
predetermined machining allowances formed respectively at its outer
periphery, raceway and side faces, a boring step 111 of forming the
lubrication holes in the blank which lubrication holes are open to
the inner periphery and the outer periphery of the blank, a heat
treatment step 112 of hardening the blank, having the lubrication
holes formed therein, to predetermined hardness, a second turning
step 113 of turning the raceway after the heat treatment step while
leaving a grinding allowance and a grinding step 114 of grinding
the outer periphery, the raceway and the side faces for finishing
purposes for finishing purposes after the second turning step are
effected in this order as shown in FIG. 8.
[0004] Patent Literature 1: JP-A-11-336753 Publication
DISCLOSURE OF THE INVENTION
Problem that the Invention is to Solve
[0005] However, the lubrication holes 107 are formed in the outer
ring 102, and therefore a discontinuous cutting operation occurs
when turning the lubrication hole (107) portions at the second
turning step 113. Therefore, along with the fact that the outer
ring 102 has been heat treated to be hardened, a strong impact
repeatedly acts on a turning tool. As a result, there have been
encountered problems that a cutting edge of the turning tool is
chipped, so that its life is shortened and that the outer raceway
102a is damaged by the turning tool having the chipped cutting
edge.
[0006] Furthermore, since the lubrication holes 107 are formed in
the outer ring 102, the discontinuous grinding operation occurs
when grinding the lubrication hole (107) portions at the above
grinding step. Therefore, a strong impact repeatedly acts on a
grindstone. Therefore, when the grinding is effected under ordinary
grinding conditions, the grindstone is liable to be broken, so that
the life of the grindstone is shortened. As a result, with respect
to the grinding conditions for the outer raceway 102a, it is
necessary, for example, to lower the rotational speed of the
grindstone during the grinding operation in order to relieve this
impact, and it is necessary to extend the grinding time in order to
effect the sufficient grinding operation. Therefore, there has been
encountered a problem that the efficiency of the grinding step is
worsened.
[0007] The present invention has been made in view of the above
problems, and its object is to provide a method of producing an
outer ring of a self-aligning bearing in which a discontinuous
cutting operation at a turning step after a heat treatment can be
avoided, and the chipping of a turning tool and damage of a raceway
can be prevented, and also a prolonged lift of a grindstone at a
grinding step and an enhanced efficiency of the grinding operation
can be achieved.
Means for Solving the Problem
[0008] In order to achieve the above object, a method of the
present invention for producing an outer ring of a self-aligning
bearing comprises a first turning step of turning an annular stock
to form a blank having a predetermined machining allowance formed
at a raceway, a boring step of forming lubrication holes in the
blank which lubrication holes are open to the raceway and an outer
periphery of the blank, a heat treatment step of hardening the
blank, having the lubrication holes formed therein, to
predetermined hardness, and a second turning step of turning the
raceway after the heat treatment step, and is characterized in that
before the heat treatment step, a turning operation is applied to
that portion of the raceway corresponding to the lubrication holes
to form an annular groove for avoiding a situation in which a
discontinuous cutting operation occurs at the second turning step
because of the lubrication holes.
[0009] In the present invention, the discontinuous cutting
operation occurring at the second turning step can be avoided by
the annular groove, and therefore the chipping of a turning tool
can be prevented.
[0010] Furthermore, a method of the present invention for producing
an outer ring of a self-aligning bearing comprises a first turning
step of turning an annular stock to form a blank having a
predetermined machining allowance formed at a raceway, a boring
step of forming lubrication holes in the blank which lubrication
holes are open to the raceway and an outer periphery of the blank,
a heat treatment step of hardening the blank, having the
lubrication holes formed therein, to predetermined hardness, a
second turning step of turning the raceway after the heat treatment
step while leaving a grinding allowance, and a grinding step of
grinding the raceway for finishing purposes after the second
turning step, and is characterized in that before the heat
treatment step, a turning operation is applied to that portion of
the raceway corresponding to the lubrication holes to form an
annular groove for avoiding a situation in which a discontinuous
cutting operation and a discontinuous grinding operation occur
respectively at the second turning step and the grinding step
because of the lubrication holes.
[0011] In the present invention, the discontinuous cutting
operation occurring at the second turning step can be avoided by
the annular groove, and therefore the chipping of the turning tool
can be prevented, and also a prolonged life of a grindstone at the
grinding step and an enhanced efficiency of the grinding operation
can be achieved.
[0012] Furthermore, a method of the present invention for producing
an outer ring of a self-aligning bearing may comprise a turning
step of turning an annular stock to form a blank having a
predetermined grinding allowance formed at a raceway, a boring step
of forming lubrication holes in the blank which lubrication holes
are open to the raceway and an outer periphery of the blank, a heat
treatment step of hardening the blank, having the lubrication holes
formed therein, to predetermined hardness, and a grinding step of
grinding the raceway for finishing purposes after the heat
treatment step, and may be characterized in that before the heat
treatment step, a turning operation is applied to that portion of
the raceway corresponding to the lubrication holes to form an
annular groove for avoiding a situation in which a discontinuous
grinding operation occurs at the grinding step because of the
lubrication holes.
[0013] In this case, the prolonged life of the grindstone at the
grinding step and the enhanced efficiency of the grinding operation
can be achieved.
ADVANTAGE OF THE INVENTION
[0014] In the method of the present invention for producing the
outer ring of the self-aligning bearing, the chipping of the
turning tool due to the discontinuous cutting operation can be
prevented, and therefore the life of this tool can be prolonged,
and also the raceway can be prevented from being damaged.
[0015] Furthermore, damage of the grindstone due to the
discontinuous grinding operation can be suppressed, and therefore
the life of the grindstone can be prolonged, and also the enhanced
efficiency of the grinding operation can be achieved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 This is a cross-sectional view showing an important
portion of a self-aligning bearing incorporating an outer ring
produced by a production method of the present invention.
[0017] FIG. 2 This is an enlarged cross-sectional view of the
important portion.
[0018] FIG. 3 This is a process drawing showing one embodiment of a
method of producing the outer ring of the self-aligning bearing
according to this invention.
[0019] FIG. 4 This is a cross-sectional view showing an important
portion of a self-aligning bearing incorporating an outer ring
produced by another production method of the present invention.
[0020] FIG. 5 This is an enlarged cross-sectional view of an
important portion of FIG. 4.
[0021] FIG. 6 This is a process drawing showing another embodiment
of a method of producing the outer ring of the self-aligning
bearing according to this invention.
[0022] FIG. 7 This is a cross-sectional view showing an important
portion of a conventional self-aligning bearing.
[0023] FIG. 8 This is an explanatory chart showing a method of
producing an outer ring of the conventional self-aligning bearing
in process order.
BEST MODE FOR CARRYING OUT THE INVENTION
[0024] Embodiments of the present invention will be described below
with reference to the drawings.
[0025] FIG. 1 is a cross-sectional view showing a self-aligning
bearing incorporating an outer ring produced by a production method
of the present invention. In this self-aligning roller bearing 1,
the outer ring 2 having a spherical outer raceway 2a formed on an
inner periphery thereof and an inner ring 3 having an inner raceway
3a of a cross-sectionally arc-shape (having the same radius as a
radius of the outer raceway 2a in a cross-section including a
center axis of this inner ring) formed on an outer periphery
thereof are disposed coaxially with each other, and a plurality of
rolling elements 4 are interposed between the outer ring 2 and the
inner ring 3.
[0026] An annular lubrication groove 6 is formed in and along an
axially-central portion of the outer periphery of the outer ring 2,
and a plurality of lubrication holes 7 for supplying lubricating
oil to the interior of the bearing are formed through the outer
ring inwardly of this lubrication groove, and are arranged at
predetermined intervals in a circumferential direction. About 3 to
8 lubrication holes 7 are formed.
[0027] Referring also to FIG. 2, an annular groove 2b is formed in
the inner periphery of the outer ring 2. This annular groove 2b is
provided in corresponding relation to the lubrication holes 7, and
each lubrication hole 7 is open to a bottom of this annular groove
2b. In the drawings, this annular groove 2b has an arc-shaped
cross-section, and its axial width C is larger than a bore diameter
d of the lubrication hole 7, and also is set to such a range that
in a condition in which the axis of the inner ring 3 is inclined to
a maximum degree relative to the axis of the outer ring 2, a
rolling contact surface of the rolling elements 4 will not overlap
the annular groove 2b. This annular groove 2b is provided for the
purpose of avoiding a situation in which a discontinuous cutting
operation and a discontinuous grinding operation occur respectively
at a second cutting step and a grinding step (which will be
described later) because of the lubrication holes 7.
[0028] The rolling elements 4 comprise respective convex rollers
made of bearing steel hardened by a heat treatment, and are
rollably interposed in a double-row manner between the outer
raceway 2a of the outer ring 2 and the inner raceway 3a of the
inner ring 3. The rolling elements 4 are held at predetermined
intervals by a cage 5.
[0029] FIG. 3 is a process drawing showing the method of producing
the outer ring 2 of the above self-aligning bearing. In this
production method, first, a steel material such as bearing steel is
hot forged to form an annular stock 11 (see FIG. 3(a)), and a
turning operation is applied to this annular stock 11 to thereby
form a blank 12 having predetermined machining allowances formed
respectively at its outer periphery, outer raceway 2a and side
faces (first turning step: see FIG. 3(b)).
[0030] Then, the lubrication groove 6 and the annular groove 2b are
formed respectively in the outer periphery and inner periphery of
the blank 12 by turning (see FIG. 3(c)). Here, the cross-sectional
shape of the annular groove 2b (formed in the inner periphery of
the blank 12 by turning) including the axis has a uniform shape in
the circumferential direction. The purpose of this is to effect the
turning operation for the annular groove 2b efficiently and also to
make the boundary between the annular groove 2b and the inner
peripheral surface of the blank 12 annular so that the
discontinuous turning operation and the discontinuous grinding
operation will be less liable to occur respectively at the second
turning step and the grinding step. Thereafter, a plurality of
lubrication holes 7 open to the lubrication groove 6 at the outer
periphery and also to the annular groove 2b at the inner periphery
are formed in the blank 12 (boring step: see FIG. 3(d)). This
lubrication hole 7 is formed by cutting the outer ring 2 in such a
manner that the drill extends radially through the outer ring.
[0031] After the lubrication holes 7 are formed, a heat treatment
such as hardening and annealing is applied to the blank 12, thereby
hardening this blank 12 to predetermined hardness, for example, of
HRC about 58 to 64 required for a bearing outer ring.
[0032] When this heat treatment step is finished, the outer raceway
2a is turned by a turning tool such as a cutting tool, while
leaving a grinding allowance (second turning step: see FIG. 3(e)).
At this time, the cutting of the lubrication hole (7) portions can
be omitted thanks to the annular groove 2b, and therefore the
discontinuous cutting operation due to the lubrication holes 7 can
be avoided.
[0033] When the second turning step is finished, the outer
periphery, the raceway 2a and the side faces are ground for
finishing purposes (grinding step: see FIG. 3(f)). At this time,
the grinding of the lubrication hole (7) portions can be omitted
thanks to the annular groove 2b, and therefore the discontinuous
grinding operation due to the lubrication holes 7 can be avoided.
Further, the raceway 2a is super finished, thus completing the
production of the outer ring 2.
[0034] As described above, in the self-aligning roller
bearing-producing method of the present invention, at the second
turning step of turning the outer raceway 2a after the heat
treatment, the discontinuous cutting operation occurring because of
the lubrication holes 7 can be avoided by the annular groove 2b,
and therefore an undesirable situation in which a strong impact
acts on the turning tool to chip its cutting edge can be prevented
from occurring. Therefore, a life of the turning tool can be
prolonged, and also the raceway can be prevented from being
damaged.
[0035] Furthermore, in the self-aligning roller bearing-producing
method of the present invention, at the grinding step after the
heat treatment, the discontinuous grinding operation occurring
because of the lubrication holes 7 can be avoided by the annular
groove 2b, and therefore the development of an undesirable
situation in which a strong impact acts on a grindstone to damage
the grindstone can be suppressed. Therefore, a life of the
grindstone can be prolonged, and also the efficiency of the
grinding step can be enhanced.
[0036] In the above embodiment, although the annular groove 2b is
formed before the boring step of forming the lubrication holes 7,
the annular groove 2b may be formed after the lubrication holes 7
are formed, and in short it is only necessary to form the annular
groove 2b before the heat treatment step.
[0037] Furthermore, in the above embodiment, although the outer
raceway 2a is ground for finishing purposes after the second
turning step, there are occasions when the grinding step is
omitted. Of courses, instead of the grinding step for the outer
raceway 2a after the second turning step, a step other than the
grinding finish step, such as a step of lapping the outer raceway
2a after the second turning step, can be effected.
[0038] FIG. 4 is a cross-sectional view showing an important
portion of a self-aligning bearing incorporating an outer ring
produced by another production method of the present invention. In
this self-aligning roller bearing 21, the outer ring 22 having a
spherical outer raceway 22a formed on an inner periphery thereof
and an inner ring 23 having an inner raceway 23a of a
cross-sectionally arc-shape (having the same radius as a radius of
the outer raceway 22a in a cross-section including a center axis of
this inner ring) formed on an outer periphery thereof are disposed
coaxially with each other, and a plurality of rolling elements 24
are interposed between the outer ring 22 and the inner ring 23.
[0039] An annular lubrication groove 26 is formed in and along an
axially-central portion of the outer periphery of the outer ring
22, and a plurality of lubrication holes 27 for supplying
lubricating oil to the interior of the bearing are formed through
the outer ring inwardly of this lubrication groove, and are
arranged at predetermined intervals in a circumferential direction.
About 3 to 8 lubrication holes 27 are formed.
[0040] Referring also to FIG. 5, an annular groove 22b is formed in
the inner periphery of the outer ring 22. This annular groove 22b
is provided in corresponding relation to the lubrication holes 27,
and each lubrication hole 27 is open to a bottom of this annular
groove 22b. In the drawings, this annular groove 22b has an
arc-shaped cross-section, and its axial width C is larger than a
bore diameter d of the lubrication hole 27, and also is set to such
a range that in a condition in which the axis of the inner ring 23
is inclined to a maximum degree relative to the axis of the outer
ring 22, a rolling contact surface of the rolling elements 24 will
not overlap the annular groove 22b. This annular groove 22b is
provided for the purpose of avoiding a situation in which a
discontinuous grinding operation occurs at a grinding step
(described later) because of the lubrication holes 27.
[0041] The rolling elements 24 comprise respective convex rollers
made of bearing steel hardened by a heat treatment, and are
rollably interposed in a double-row manner between the outer
raceway 22a of the outer ring 22 and the inner raceway 23a of the
inner ring 23. The rolling elements 24 are held at predetermined
intervals by a cage 25.
[0042] FIG. 6 is a process drawing showing the method of producing
the outer ring 22 of the above self-aligning bearing. In this
production method, first, a steel material such as bearing steel is
hot forged to form an annular stock 31(see FIG. 6(a)), and a
turning operation is applied to this annular stock 31 to thereby
form a blank 32 having predetermined grinding allowances formed
respectively at its outer periphery, outer raceway 22a and side
faces (first turning step: see FIG. 6(b)).
[0043] Then, the lubrication groove 26 and the annular groove 22b
are formed respectively in the outer periphery and inner periphery
of the blank 32 by turning (see FIG. 6(c)). Here, the
cross-sectional shape of the annular groove 22b (formed in the
inner periphery of the blank 32 by turning) including the axis has
a uniform shape in the circumferential direction. The purpose of
this is to effect the turning operation for the annular groove 22b
efficiently and also to make the boundary between the annular
groove 22b and the inner peripheral surface of the blank 32 annular
so that the discontinuous grinding operation will be less liable to
occur at the grinding step. Thereafter, a plurality of lubrication
holes 27 open to the lubrication groove 26 at the outer periphery
and also to the annular groove 22b at the inner periphery are
formed in the blank 32 (boring step: see FIG. 6(d)). This
lubrication hole 27 is formed by cutting the outer ring 22 by a
drill in such a manner that the drill extends radially through the
outer ring.
[0044] After the lubrication holes 27 are formed, a heat treatment
such as hardening and annealing is applied to the blank 32, thereby
hardening this blank 32 to predetermined hardness, for example, of
HRC about 58 to 64 required for a bearing outer ring.
[0045] When this heat treatment step is finished, the outer
periphery, the raceway 2a and the side faces are ground for
finishing purposes (grinding step: see FIG. 6(f)). At this time,
the grinding of the lubrication hole (27) portions can be omitted
thanks to the annular groove 22b, and therefore the discontinuous
grinding operation due to the lubrication holes 27 can be avoided.
Further, the raceway 2a is super finished, thus completing the
production of the outer ring 2.
[0046] In the self-aligning roller bearing-producing method of the
present invention, at the grinding step after the heat treatment,
the discontinuous grinding operation occurring because of the
lubrication holes 27 can be avoided by the annular groove 22b, and
therefore the development of an undesirable situation in which a
strong impact acts on a grindstone to damage the grindstone can be
suppressed. Therefore, a life of the grindstone can be prolonged,
and also the efficiency of the grinding step can be enhanced.
[0047] In the above embodiment, although the annular groove 22b is
formed before the boring step of forming the lubrication holes 27,
the annular groove 22b may be formed after the lubrication holes 27
are formed, and in short it is only necessary to form the annular
groove 22b before the heat treatment step.
* * * * *