[0001]The present disclosure relates to a single-row deep groove ball bearing, and for
example, to a ball bearing for use in a semi-floating rear axle, in which an inner ring is
conveyed by an elevator conveyor during manufacture, and a method of manufacturing
the same.
Background Art
[0002]The semi-floating type wheel support device is simple in structure and
inexpensive, and allows easy replacement of a ball bearing for a semi-floating rear axle
15 (hereinafter, also referred to as "ball bearing"), and thus is widely installed in taxi vehicles
and small commercial vehicles (e.g., vans and trucks) with high mileages. This wheel
support device has a ball bearing press-fitted and fixed lo an outer circumferential surface
of an axle (axle shaft) with a wheel mount installed at an end thereof, and the axle shaft
is rotatably supported through the ball bearing.
20 [0003]
It is known that this type of ball bearing has a projecting portion formed on an
inner ring in an axial direction and that an axial dimension (width) of the inner ring is
greater than the axial dimension of an outer ring (see, for example, JP-A-2002-013539).
That is, the inner ring of this type of ball bearing with the projecting portion formed
25 thereon is provided in an asymmetric structure in the axial direction with reference to an
inner ring raceway groove formed therebetween.
[0004]
When grinding and superfinishing works are performed for the inner ring
raceway groove of the inner ring of the asymmetric structure as described above, the inner
30 ring raceway groove is disposed at a position deviated away from the center of the inner
ring full width, and accordingly it is necessary to align the inner ring in a predetermined
direction during the manufacturing process.
[0005]
Therefore, in order to align the asymmetrically-structured inner ring, the center
of gravity of the inner ring of the asymmetric structure is biased toward one side with
respect to the center in the axial direction and an elevator conveyor arranged obliquely to
5 the direction of gravity is used. The elevator conveyor aligns the direction of the inner
rings, while conveying the inner rings accommodated in the hopper one by one, or
conveying a plurality of inner rings at a time, from lower to upper directions.
[0006]
Atypical example of conveying an inner ring of an asymmetric structure with an
10 elevator conveyor will be described with reference to Figs. 7 and 8. Fig. 7 is a crosssectional
view illustrating a related inner ring of a ball bearing being conveyed, with a
projecting portion thereof being engaged with a claw portion of an elevator conveyor.
Fig. 8 is a cross-sectional view illustrating a related inner ring of a ball bearing being
conveyed, with a projecting portion thereof being engaged with a claw portion of the
15 elevator conveyor at an opposite end in the axial direction.
[0007]
As illustrated in Figs. 7 and 8, the inner ring 52 has an asymmetrical structure in
the axial direction with reference to an inner ring raceway groove 52a formed in between,
and the inner ring 52 has a projecting portion 52c projecting outward in the axial direction
20 from one axial end (left end in Fig. 7, right end in Fig. 8). In addition, a small-diameter
stepped portion 52d is formed along the outer circumferential surface of the other end
(right end in Fig. 7, left end in Fig. 8) of the inner ring 52 in the axial direction. In
addition, the inner ring 52 has a pair of shoulders 52b adjacent to the inner ring raceway
groove 52a along an outer circumferential surface of the inner ring raceway groove 52a,
25 and one of the pair of shoulders 52b forms a projecting portion 52c. In addition, the
outer circumferential surface of the projecting portion 52c and the outer circumferential
surface of the shoulder 52b close to the small-diameter stepped portion 52d are each
formed as a cylindrical surface having a uniform diameter.
[0008]
30 The elevator conveyor 60 includes a belt 61, and a claw portion 62 provided on
a surface oi the belt 61 for loading an inner ring 52. The claw portion 62 is formed in a
rectangular shape in cross section in the direction of gravity, and in a linear shape in the
width direction of the belt 61. The elevator conveyor 60 is loaded with the inner ring
52, with the outer circumferential surface of the inner ring 52 being on the upper surface
of the claw portion 62, and conveys the inner ring 52 to an upper direction.
[0009]
5 Specifically, as illustrated in Fig. 7, when one end surface of the inner ring 52 on
the projecting portion 52c is positioned on the side of the belt 61, the inner ring 52 is
conveyed with the outer circumferential surface of the projecting portion 52c of the inner
ring 52 being engaged with the upper surface of the claw portion 62. Then, referring to
Fig. 7 that illustrates the inner ring in the state of being conveyed, since the vertical line
10 L passing through the center of gravity G of the inner ring 52 passes through in a certain
range of the upper surface of the claw portion 62 or in a certain range of the side of the
belt 61 (left side in Fig. 7) rather than the upper surface of the claw portion 62, the inner
ring 52 is conveyed to the next process without dropping apart from the claw portion 62.
[0010]
15 On the other hand, as illustrated in Fig. 8, when the other end surface of the inner
ring 52 on the small-diameter stepped portion 52d side is positioned on the belt 6! side,
the inner ring 52 is conveyed with the outer circumferential surface of the shoulder 52b
on the small-diameter stepped portion 52d of the inner ring 52 being engaged with the
upper surface of the claw portion 62. However, in the conveyance state illustrated in
20 Fig. 8, since the vertical line L passing through the center of gravity G of the inner ring
52 is positioned on a side farther away from the belt 61 than the claw portion 62, the inner
ring 52 is turned in a direction (in the direction of arrow B in Fig. 8) away from the belt
61 about a connecting area between the inner ring 52 and the claw portion 62, and the
inner ring 52 drops apart from the claw portion 62 during conveyance. Therefore, when
25 the other end surface of the inner ring 52 on the small-diameter stepped portion 52d side
is positioned on the side of the belt 61, the inner ring 52 is not conveyed to the next
process.
[0011]
When the inner ring 52 is turned and drops apart from the belt 61, the distance of
30 dropping increases, and denting occurs in the inner ring 52, and when the dropping is
severe, it causes microcracks to be generated in the bottom of the dent, possibly resulting
in damage such as delayed fracture of the inner ring 52.
T
j
[0012]
Meanwhile, in the inner ring of the ball bearing disclosed in JP-A-2G02-013539,
since the small-diameter stepped portion is formed on the outer circumferential surface
of the projecting portion and the large chamfered portion is formed on the inner
5 circumferential surface of the projecting portion, there is a large reduced section formed
on the projecting part of the inner ring. Therefore, between when the end surface on the
same side as the projecting portion of the inner ring is positioned on the side of the belt
and when the end surface on a side separated away from the projecting portion of the
inner ring is positioned on the side of the bell, there is a less movement of the center of
10 gravity from the axial center of the inner ring. Therefore, in the case of the inner ring
of the ball bearing disclosed in .TP-A-2002-013539, it is difficult to apply the method of
aligning the directions of the inner rings illustrated in Figs. 7 and 8.
15 [0013]
The present disclosure has been made in view of the problems described above,
and it is an objective of the present disclosure to provide a single-row deep groove ball
bearing capable of preventing the inner ring from being damaged by slowing the dropping
speed of the inner ring when the inner ring drops apart from the elevator conveyor, and a
20 manufacturing method thereof.
[0014]
The above object of the present disclosure is achieved by the following
constitution.
According to a first aspect of the invention, there is provided a single-row deep
25 groove ball bearing including: an outer ring including an outer ring raceway groove
formed in an inner circumferential surface thereof; an inner ring including an inner ring
raceway groove formed in an outer circumferential surface thereof; and a plurality of balls
provided rollably between the outer ring raceway groove and the inner ring raceway
groove, wherein: the inner ring has an asymmetric structure in an axial direction in which
30 one and the other axiai ends across the inner ring raceway groove formed therebetween
in the axiai direction have different shapes from each other; the other end of the inner ring
includes a first small-diameter stepped portion formed thereon; and an inner race-side
4
chamfer portion larger than a chamfer portion provided on an outer circumferential edge
of a first shoulder of a pair of shoulders is provided on an outer circumferential edge of a
second shoulder of the pair of shoulders adjacent to the inner ring raceway of the inner
ring.
5 According to a second aspect of the invention, in the single-row deep groove ball
bearing of the first aspect, an axial dimension from the inner ring raceway groove to one
axial end surface of the inner ring is greater than an axial dimension from the inner ring
raceway groove to the other axial end surface of the inner ring.
According to a third aspect of the invention, in the single-row deep groove ball
10 bearing of the first or second aspect, an intersection angle between a center axis of the
inner ring and a straight line passing through the inner ring-side chamfer portion and a
center of gravity of the inner ring is set to a range of 55° to 75°.
According to a fourth aspect of the invention, in the single-row deep groove ball
bearing of any one of the first to third aspects, the inner ring is conveyed upward from
15 below by an elevator conveyor disposed obliquely with respect to a direction of gravity,
the elevator conveyor includes a belt and a claw portion provided on a surface of the belt
and configured to load the inner ring, the claw portion is formed in a rectangular shape in
cross section in the direction of gravity, a claw side-chamfer portion is formed on an edge
portion between an upper surface and a side surface of the claw portion, the inner race-
20 side chamfer portion larger than the chamfer portion provided on the outer circumferential
edge of the first shoulder of the pair of shoulders is provided on the outer
circumferential edge of the second shoulder of the pair of shoulders adjacent to the inner
ring raceway of the inner ring, and when the inner ring is conveyed by the claw portion
of the elevator conveyor, the inner ring-side chamfer portion is positioned to face the claw
25 side-chamfer portion, and also positioned on a vertical line passing through the center of
gravity the inner ring.
According to a fifth aspect of the invention, in the single-row deep groove ball
bearing of the fourth aspect, a second small-diameter stepped portion Is formed on one
axial end of the inner ring, the second small-diameter stepped portion is provided at the
30 same time as the inner ring raceway groove by grinding, and an intersection angle
between a direction of conveying of the elevator conveyor and a horizontal plane
orthogonal to the direction of gravity is set to be equal to or greater than an intersection
5
angle between the center axis of the inner ring and a straight line passing through the
inner ring-side chamfer portion and the center of gravity of the inner ring.
[0015]
According to the invention, the inner ring has an asymmetric structure in an axial
5 direction in which one and the other axial ends across the inner ring raceway groove
formed therebetween in the axial direction have different shapes from each other, the
other end of the inner ring includes a first small-diameter stepped portion formed thereon,
and a pair of shoulders are formed adjacent to the inner ring raceway groove of the inner
ring, and an inner race-side chamfer portion is provided on an outer circumferential edge
10 of a second shoulder of the pair of shoulders, and the inner race-side chamfer portion is
larger than a chamfer portion provided on an outer circumferential edge of a first shoulder
of the pair of shoulders, and when the inner ring is conveyed by the claw portion of the
elevator conveyor, the inner ring-side chamfer portion is positioned to face the claw sidechamfer
portion of the claw portion and is positioned on a vertical line passing through
15 the center of gravity of the inner ring. Therefore, since the inner ring-side chamfer
portion of the inner ring is slid down along the claw side-chamfer portion of the claw
portion and the inner ring is slid along the belt without turning inside out, it is enabled to
slow the speed of the dropping inner ring and to prevent damage to the inner ring.
20 Brief Description of the Drawings
[0016J
Fig. 1 is a cross-sectional view illustrating a first embodiment of a single-row
deep groove bail bearing according to the present disclosure;
Fig. 2 is a cross-sectional view illustrating a state in which the inner ring
25 illustrated in Fig. 1 is conveyed, while being engaged with a claw portion at one shoulder;
Fig. 3 is a cross-sectional view illustrating a state in which the inner ring
illustrated in Fig. 1 is conveyed, while being engaged with a claw portion at the other
shoulder;
Fig. 4 is a cross-sectional view illustrating a modified example of the first
30 embodiment of the single-row deep groove ball bearing according to the present
disclosure;
Fig. 5 is a cross-sectional view illustrating a modified example of the second
6
embodiment of the single-row deep groove ball bearing according to the present
disclosure;
Fig. 6 is a cross-sectional view illustrating a state in which the inner ring
illustrated in Fig. 5 is conveyed, while being engaged with a claw portion at one shoulder;
5 Fig. 7 is a cross-sectional view illustrating a related inner ring of a ball bearing
being conveyed, with a projecting portion thereof being engaged with a claw portion of
an elevator conveyor; and
Fig. 8 is a cross-sectional view illustrating a related inner ring of a ball bearing
being conveyed, with a projecting portion thereof being engaged with a claw portion of
10 the elevator conveyor at an opposite end in the axial direction.
[0017]
Hereinafter, respective embodiments of the single-row deep groove ball bearing
15 according to the present disclosure will be described in detail based on the drawings. In
addition, the single-row deep groove ball bearing (hereinafter also referred to as "ball
bearing") is a roll bearing mounted on a semi-floating type wheel support device and is
used to rotatably support the rear wheel (driven wheel) of the vehicle. In addition, in
the support device of semi-floating type, the axle (axle shaft) is housed in a housing (axle
20 housing) through a ball bearing. Accordingly, ihe ball bearing of the present
embodiment is installed on an outer circumferential surface of the axle shaft.
[0018]
First embodiment
First, the first embodiment of single-row deep groove ball bearing according to
25 the present disclosure will be described with reference to Figs. 1 to 4.
[0019]
As illustrated in Fig. !, the ball bearing (single-row deep groove ball bearing) 10
of the present embodiment includes an outer ring 11, which is a stationary raceway ring,
an inner ring 12, which is a rotating raceway ring, and a plurality of balls 13 rollably
30 provided between an outer ring raceway groove 11 a of the outer ring 11 and an inner ring
raceway groove 12a of the inner ring 12. a cage 14 for holding the plurality of balls 13 at
substantially equal intervals in the circumferential direction, and first and second sealing
7
devices 15, 16 attached to both ends ofthe inner circumferential surface ofthe outer ring
11. Further, lubricant (for example, grease) is contained in an inner space ofthe bearing.
[0Q20J
The outer ring 11 includes the outer ring raceway groove 11 a formed at a center
ofthe inner circumferential surface thereof in the axial direction, and a pair of shoulders
1 lb adjacent to the outer ring raceway groove 1J a. One and the other ends ofthe outer
ring 11 across the outer ring raceway groove 11a formed therebetween in the axial
direction have approximately the same shape as each other.
[0021]
The inner ring 12 has the inner ring raceway groove 12a formed on the outer
circumferential surface thereof, and a pair of shoulders 12b adjacent to the inner ring
raceway groove 12a. In addition, the inner ring 12 has an asymmetric structure in the
axial direction, in which one and the other axial ends across the inner ring raceway groove
12a formed therebetween in the axial direction have different shapes from each other, and
is formed such that the axial dimension Bl from the bottom ofthe inner ring raceway
groove 12a to the one axial end surface 12c ofthe inner ring 12 is greater than the axial
dimension B2 from the bottom ofthe inner ring raceway groove 12a to the other axial
end surface 12d ofthe inner ring 12. Therefore, the axial dimension ofthe inner ring 12
is greater than the axial dimension ofthe outer ring 11, and one axial end ofthe inner ring
12 projects axially outboard beyond one axial end surface ofthe outer ring 11. In
addition, the other axial end surface ofthe inner ring 12 has substantially the same axial
position as the other axial end surface ofthe outer ring 11.
[0022]
In addition, a tapered or arc-shaped chamfer portion 12e is formed along the outer
circumferential edge ofthe shoulder 12b on one axial side (the right side in Fig. 1) ofthe
inner ring 12. In addition, the outer circumferential surfaces ofthe pair of shoulders 12b
are each formed as a cylindrical surface having a uniform diameter.
[0023]
In addition, a first small-diameter stepped portion 12f having a bottom surface
12g and a side surface 12h is formed along the outer circumferential surface ofthe other
axial end (the left end in Fig. 1) ofthe inner ring 12, in a smaller diameter than the outer
circumferential surface ofthe shoulder 12b. The bottom surface 12g ofthe first smallo
o
diameter stepped portion 12f is formed as a tapered surface that decreases in diameter in
an axial ly outward direction.
[0024]
In addition, a tapered, inner ring-side chamfer portion 12i is formed along the
5 outer circumferential edge of the shoulder 12b on the other axial side of the inner ring 12.
that is, along an edge between the side surface 12h of the first small-diameter stepped
portion 12f and the outer circumferential surface of the shoulder 12b on the other axial
side (left side in Fig. 1). That is, the first small-diameter stepped portion 12f is provided
on the axial end that is on the side of the inner ring 12 where the inner ring-side chamfer
10 portion 12i is provided. The chamfer portion 12s has a greater dimension in a radial
direction and in an axial direction than the chamfer portion 12e of the shoulder 12b on
one side.
[0025]
The first sealing device 15 is disposed outside a vehicle in an assembled state,
15 and provides a seal to prevent intrusion of external dust and muddy water from entering
the ball bearing, in which a radial lip is brought into sliding contact with the outer
circumferential surface of the shoulder 12b on one side of the inner ring 12, and aside lip
is in sliding contact with the axially inboard surface of an annular portion of aslinger 15a
having an L-shaped cross section, in which the cylindrical portion is engaged with the
20 outer circumferential surface of the shoulder 12b on one side of the inner ring 12. The
second sealing device 16 is to provide a seal that prevents the differential gear oil
contained in the axle tube from rinsing off the lubricant contained in the ball bearing, and
the radial lip is in sliding contact with the bottom surface 12g of the first small-diameter
stepped portion 12fofthe inner ring 12.
25 [0026]
Next, the manufacturing process of the inner ring 12 will be described. - The
manufacturing process of the inner ring 12 includes at least: a conveying process of
conveying the inner ring 12 having the inner ring-side chamfer portion 12i formed
thereon, with an elevator conveyor 20 to be described later; and a raceway groove
30 machining process (grinding process or superfinishing process) of machining the inner
ring raceway groove 12a of the conveyed inner ring 12.
[0027]
9
In the conveying process, the inner ring 12 is aligned in a predetermined direction
and conveyed to the raceway groove processing process. In the raceway groove
processing process., grinding and superfinishing are performed for the inner ring raceway
groove 12a of the inner ring 12. The inner ring-side chamfer portion 12i. the chamfer
5 portion 12e, and the first small-diameter stepped portion 12f of the inner ring 12 are
formed by a machining process or the like in advance before the conveying process.
[0028]
Next, the conveying process of the inner ring 12 will be described in detail with
reference to Figs. 2 and 3.
10 [0029]
In the conveying process, as illustrated in Figs. 2 and 3, the inner ring 12 is
conveyed from the lower to upper directions by an elevator conveyor 20 disposed
obliquely with respect lo the direction of gravity (vertical direction in Figs. 2 and 3).
That is, the direction of conveying D of the elevator conveyor 20 is set obliquely with
15 respect to the direction of gravity.
[0030]
The elevator conveyor 20 includes a belt 21, and a claw portion 22 provided on
a surface of the belt 21 for loading an inner ring 12. The claw portion 22 is formed in a
rectangular shape in cross section in the direction of gravity, and in a linear shape in the
20 width direction of the belt 21. In addition, a curve-shaped claw side-chamfer portion
22a is formed on an edge between the upper surface and the side surface of the claw
portion 22. The elevator conveyor 20 is loaded with the inner ring 12 on the upper
surface of the claw portion 22 and conveys the inner ring 12 upward.
[0031]
25 Then, as illustrated in Fig. 2, when the inner ring 12 is conveyed with the one
axial end surface 12c of the inner ring 12 being positioned on the side of the belt 21, the
outer circumferential surface of the shoulder 12b on the one side of the inner ring 12 is
engaged with the upper surface of the claw portion 22. At this time, since the vertical
line L passing through the center of gravity G of the inner ring 12 is positioned in a certain
30 range of the upper surface of the claw portion 22 or in a certain range of the belt 21 rather
than the upper surface of the claw portion 22. the inner ring 12 is conveyed to the next
process without dropping apart from the claw portion 22. Further, the center of gravity
10
G of the inner ring 12 is positioned on the central axis C (axial line passing through the
center in a radial direction) of the inner ring 12.
[0032]
Meanwhile, as illustrated in Fig. 3, when the inner ring 12 is conveyed with the
5 other axial end surface 12d of the inner ring 12 being positioned on the side of the belt
21, the inner ring-side chamfer portion 12i is engaged with the claw side-chamfer 22a of
the claw portion 22. At this time, since the inner ring-side chamfer portion !2i is
positioned to face the claw side-chamfer 22a and is positioned on a vertical line L passing
through the center of gravity G of the inner ring 12, the inner ring-side chamfer portion
10 12i is slid down along the claw side-chamfer 22a (see arrow A in Fig. 3) and the inner
ring 12 is slid along the belt 21 without turning inside out. Therefore, the inner ring 12
drops apart from the clawr portion 22 and is not conveyed to the next process. In
addition, since the speed of the dropping inner ring 12 is slowed when the inner ring 12
is slid along the belt 21, damage to the inner ring 12 is prevented.
15 [0033]
As described above, with the single-row deep groove ball bearing 10 and a
manufacturing method thereof according to the present embodiment, when the inner ring
12 is conveyed by the claw portion 22 of the elevator conveyor 20, the inner ring-side
chamfer portion 12i is positioned to face the claw side-chamfer 22a and is positioned on
20 a vertical line L passing through the center of gravity G of the inner ring 12. Therefore,
since the inner ring-side chamfer portion 12i of the inner ring 12 is slid down along the
claw side-chamfer portion 22a of the claw portion 22 and the inner ring 12 is slid along
the belt 21 without turning inside out, it is enabled to slow the speed of the dropping inner
ring 12 and to prevent damage to the inner ring 12.
25 [0034]
In addition, with the single-row deep groove ball bearing 10 and a manufacturing
method thereof according to the present embodiment, since the bottom surface 12g of the
first small-diameter stepped portion 12f ofthe inner ring 12 is formed as a tapered surface
that decreases in diameter in an axially outward direction, when the inner ring-side
30 chamfer portion 121 ofthe inner ring 12 is slid down along the claw side-chamfer 22a of
the claw portion 22, the bottom surface 12g ofthe first small-diameter stepped portion
12f is not locked with the claw portion 22, and accordingly, the inner ring 12 is slid down
If
without getting caught. Therefore, the inner ring 12 can be slid along the bell 21 without
turning inside out.
[0035]
In a modified example of the present embodiment, as illustrated in Fig. 4. one
5 axial end surface of the outer ring 11 corresponding to the one axial end of the inner ring
12 may have a smaller protruding width. The first sealing device 15 is provided in the
same structure as the second sealing device 16, having the second small-diameter stepped
portion 12k formed along the outer circumferential surface of the one axial end (right end
in Fig. 4) of the inner ring 12. In this modified example, as illustrated in Figs. 2 and 3,
10 the inner ring 12 can be aligned in a predetermined direction and conveyed to the next
process.
[0036]
Second embodiment
Next, the second embodiment of the single-row deep groove ball bearing
15 according to the present disclosure will be described with reference to Figs. 5 and 6. The
same or equivalent parts as those in the first embodiment are given the same reference
numerals in the drawings and their explanation is omitted or simplified.
[0037]
In the present embodiment, as illustrated in Fig. 5, a second small-diameter
20 stepped portion 12m having a bottom surface 12n and a side surface 12p is formed along
an outer circumferential surface of one axial end (right end in Fig. 5) of the inner ring 12
to reduce a diameter from that of the outer circumferential surface of the shoulder 12b.
The second small-diameter stepped portion 12m is larger in diameter than the first smalldiameter
stepped portion 12f of the other axial end. In addition, the bottom surface 12n
25 of the second small-diameter stepped portion 12m is formed as a cylindrical surface
having a uniform diameter, and the side surface 12p of the second small-diameter stepped
portion 12m is formed as a tapered surface that decreases in diameter in an axially
outward direction. In addition, the slinger 15a is fitted in the bottom surface I2n of the
second small-diameter stepped portion 12m.
30 [0038]
The second small-diameter stepped portion 12m is formed by grinding at the
same time as the inner ring raceway groove 12a of the inner ring 12 during the raceway
12
groove processing process of the manufacturing process described above.
[0039]
In addition, in the present embodiment, an intersection angle a between the
central axis C of the inner ring 12 and the straight line E passing through the inner ring-
5 side chamfer portion 12i and the center of gravity G of the inner ring 12 is set to a range
of 55° to 75°. or more preferably, in a range of 60° to 70°. More specifically, the straight
line E is a straight line passing between inner and outer axial ends of the inner ring-side
chamfer portion 12i. Therefore, both of the intersecting angle a between the center axis
C of the inner ring 12 and a straight line E passing through an inner end of the inner ring-
10 side chamfer portion 12i and the center of gravity G of the inner ring 12, and the
intersection angle a between the center axis C of the inner ring 12 and a straight line E
passing through the outer axial end of the inner ring-side chamfer portion 12i and the
center of gravity G of the inner ring 12 are set in the range of 55° to 75°, or more
preferably in the range of 60° to 70°. In the present embodiment, the intersection angle
15 a is 63° to 66°.
[0040]
Further, in the present embodiment, as illustrated in Fig. 6, the intersection angle
p between the direction of conveying D of the elevator conveyor 20 and the horizontal
plane F orthogonal to the direction of gravity (— vertical line L), is set to be equal to or
20 greater than an intersecting angle a (p > a) between the center axis c of the inner ring 12
and the straight line E passing through the inner ring-side chamfer portion 12i and the
center of gravity G of the inner ring 12. That is, in the present embodiment, the
intersection angle p is set to be equal to or greater than 66°,
[0041]
25 With the intersection angles a and p set as described above, when the inner ring
32 is conveyed with the other axial end surface 12d of the inner ring 12 being positioned
on the side of the belt 21, the inner ring-side chamfer portion 121 is slid down along the
claw side-chamfer 22a (see arrow A in Fig. 6) and the inner ring 12 is slid along the belt
21 without turning inside out. Therefore, the inner ring 12 drops apart from the claw
30 portion 22 and is not conveyed to the next process. In addition, since the speed of the
dropping inner ring 12 is reduced when the inner ring 12 is slid along the belt 21, damage
to the inner ring 12 is prevented.
13
[0042]
In addition, when the inner ring 12 is conveyed with the one axial end surface
12c of the inner ring 12 being positioned close to the belt 21, likewise the inner ring 12
illustrated in Fig. 2, since the vertical line L passing through the center of gravity G of the
5 inner ring 12 is positioned in a certain range of the upper surface of the claw portion 22
or in a certain range of the belt 21 rather than the upper surface of the claw portion 22,
the inner ring 12 is conveyed to the next process without dropping apart from the claw
portion 22.
[0043]
10 As described above, with the single-row deep groove ball bearing 10 and a
manufacturing method thereof according to the present embodiment, the intersection
angle a between the central axis C of the inner ring 12 and the straight line E passing
through the inner ring-side chamfer portion 12i and the center of gravity G of the inner
ring 12 is set to a range of 55° to 75°, and the intersection angle P between the direction
15 of conveying D of the elevator conveyor 20 and the horizontal plane F orthogonal to the
direction of gravity is set to be equal to or greater than an intersecting angle a between
the center axis c of the inner ring 12 and the straight line E passing through the inner ringside
chamfer portion 12i and the center of gravity G of the inner ring 12. Therefore,
since the inner ring-side chamfer portion 12i of the inner ring 12 is slid down along the
20 claw side-chamfer portion 22a of the claw portion 22 and the inner ring 12 is slid along
the belt 21 without turning inside out, it is enabled to reduce the speed of the dropping
inner ring 12 and to prevent damage to the inner ring 12.
[0044]
In addition, according to the single-row deep groove ball bearing 10 of the
25 present embodiment, since the second small-diameter stepped portion 12m is formed on
the outer circumferential surface of the one axial end of the inner ring 12, it is possible to
increase the size of the first sealing device 15 in the radial direction and further prevent
water intrusion from the engaging surface between the inner circumferential surface of
the slinger 15a and the bottom surface 12n of the second small-diameter stepped portion
30 12m, thereby improving the water resistance of the bearing.
[0045]
Tn addition, according to the single-row deep groove ball bearing 10 of the
14
present embodiment, since the second small-diameter stepped portion 12m is formed at
the same time as the inner ring raceway groove 12a by grinding, the grinding resistance
can be reduced when grinding the shoulder 12b, as compared with the inner ring 12 as
illustrated in Fig. 1 in which the second small-diameter stepped portion 12m is not
5 formed. More specifically, as compared with the machining process, the grinding
process involves a greater working resistance and particularly so in a radial direction,
which often causes deformation of a ground workpiece. Therefore, in the present
embodiment the second small-diameter stepped portion 12m is provided to reduce the
portion to grind during grinding of the shoulder 12b. As a result, the grinding resistance
10 can be reduced, so that the roundness of the inner ring 12 can be increased. Other
configurations and operational effects are the same as those described in the first
embodiment.
[0046]
It should be noted that the present disclosure is not limited to those exemplified
15 in the embodiments described above, and can be appropriately modified without
departing from the gist of the present disclosure.
For example, in the embodiments described above, the present disclosure is
applied to the inner ring of an asymmetric structure in the axial direction, but the present
disclosure is not limited the specific example only, and accordingly, the present disclosure
20 may be applied to the inner ring having a symmetrical structure in the axial direction. Tn
this case, an example may be applicable for aligning the direction of engraving of the
inner ring.
Further, while the embodiments described above illustrate the inner ring-side
chamfer portion as a tapered chamfer portion and the claw side-chamfer as a curved
25 chamfer portion, the present disclosure is not limited to such specific example only, and
accordingly, the inner ring-side chamfer may be a curved chamfer portion, and the claw
side-chamfer may be tapered chamfer portion. In addition, both the inner ring-side
chamfer portion and the claw side-chamfer portion may be tapered or curved chamfer
portion as well.

CLAIMS:
1. A single-row deep groove ball bearing comprising:
an outer ring including an outer ring raceway groove formed in an inner
5 circumferential surface thereof;
an inner ring including an inner ring raceway groove formed in an outer
circumferential surface thereof; and
a plurality of balls provided rollably between the outer ring raceway groove and
the inner ring raceway groove, wherein:
10 the inner ring has an asymmetric structure in an axial direction in which one and
the other axial ends across the inner ring raceway groove formed therebetween in the
axial direction have different shapes from each other:
the other end of the inner ring includes a first small-diameter stepped portion
formed thereon; and
15 an inner race-side chamfer portion larger than a chamfer portion provided on an
outer circumferential edge of a first shoulder of a pair of shoulders is provided on an outer
circumferential edge of a second shoulder of the pair of shoulders adjacent to the inner
ring raceway of the inner ring.
20 2. The single-row deep groove ball bearing according to claim 1, wherein
an axial dimension from the inner ring raceway groove to one axial end surface
of the inner ring is greater than an axial dimension from the inner ring raceway groove to
the other axial end surface of the inner ring.
25 3. The single-row deep groove bail bearing according to claim 1 or 2, wherein
an intersection angle between a center axis of the inner ring and a straight line
passing through the inner ring-side chamfer portion and a center of gravity of the inner
ring is set to a range of 55° to 75°.
4. A method of manufacturing the single-row deep groove ball bearing according to
any of claims 1 to 3, wherein:
the inner ring is conve)'ed upward from below by an elevator conveyor disposed
6
obliquely with respect to a direction of gravity;
the elevator conveyor includes a belt and a claw portion provided on a surface of
the belt and configured to load the inner ring;
the claw portion is formed in a rectangular shape in cross section in the direction
5 of gravity;
a claw side-chamfer portion is formed on an edge portion between an upper
surface and a side surface of the claw portion;
the inner race-side chamfer portion larger than the chamfer portion provided on
the outer circumferential edge of the first shoulder of the pair of shoulders is provided on
10 the outer circumferential edge of the second shoulder of the pair of shoulders adjacentto
the inner ring raceway of the inner ring; and
when the inner ring is conveyed by the claw portion of the elevator conveyor, the
inner ring-side chamfer portion is positioned to face the claw side-chamfer portion, and
also positioned on a vertical line passing through the center of gravity the inner ring.
15
5. The method of manufacturing the single-row deep groove ball bearing according
to claim 4„ wherein:
a second small-diameter stepped portion is formed on one axial end of the inner
ring;
20 the second small-diameter stepped portion is provided at the same time as the
inner ring raceway groove by grinding; and
an intersection angle between a direction of conveying of the elevator conveyor
and a horizontal plane orthogonal to the direction of gravity is set to be equal to or greater
than an intersection angle between the center axis of the inner ring and a straight line
25 passing through the inner ring-side chamfer portion and the center of gravity of the inner
ring.