Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
1999-02-02
2001-05-01
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S513000, C384S515000
Reexamination Certificate
active
06224265
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a flanged ball bearing for use in various precision devices, office automation equipment, etc.
2. Description of the Related Art
It has been customary to manufacture miniature ball bearings and small-diameter ball bearings (hereinafter referred to as “small-size ball bearings”) classified according to Japan Industrial Standard by a cutting process which is capable of easily achieving a desired level of dimensional accuracy. However, the cutting process fails to accomplish a greater reduction in the cost of manufacture of such small-size ball bearings.
Japanese laid-open patent publication No. 7-224840, for example, discloses a process of inexpensively manufacturing small-size ball bearings. According to the disclosed process, the outer race of a small-size ball bearing is produced by pressing a steel sheet to shape. For improving the load-resistance capability of small-size ball bearing, it is necessary to increase the thickness of a steel sheet that is pressed into the outer race. However, a steel sheet of increased thickness cannot easily be shaped by a spinning process. If the outer race of a small-size ball bearing is to be made of a steel sheet of increased thickness, then the process of forming the outer race will entail a substantial increase in the cost in order to achieve desired dimensional accuracy of the track of the outer race.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a flanged ball bearing which is highly resistant to loads on the outer race thereof, whose outer race can be manufactured without a substantial increase in the cost, and which meets desired dimensional accuracy requirements.
To achieve the above object, there is provided in accordance with the present invention a flanged ball bearing comprising an inner race, an outer race made of sheet steel, the outer race being disposed around the inner race with an annular space defined therebetween, the outer race having a flange extending radially outwardly, and a plurality of balls disposed in the annular space, the inner race having a ball groove defined in an outer circumferential surface thereof, the outer race comprising a first annular member and a second annular member which are joined to each other, the first annular member having a first ball guide surface having an arcuate cross-sectional shape, the second annular member having a second ball guide surface having an arcuate cross-sectional shape, each of the balls being rollingly supported by the first ball guide surface, the second ball guide surface, and the surface of the ball groove.
Since the balls are rollingly held in surface-to-surface contact with the two ball guide surfaces of the outer race and the surface of the ball groove, the balls have relatively large areas of contact with the outer and inner races. Furthermore, because the outer race comprises the two annular members, each of the annular members can easily be pressed to shape even if it has an increased wall thickness. As a result, the outer race can have an increased wall thickness for increased resistance to loads applied to the ball bearing.
A radial load is applicable along a radial central line passing through the center of each of the balls, and the inner race is held in contact with each of the balls in an axial contact range having opposite ends which are symmetrical with respect to the radial central line, and the outer race is held in contact with each of the balls in an axial contact range having opposite ends which are symmetrical with respect to the radial central line.
Therefore, even when a radial load in excess of a certain level is applied to the ball bearing, the balls roll stably, and the outer race is prevented from being reduced in durability. Accordingly, when a shaft fitted in the inner race rotates, the shaft does not produce vibrations and noise, and can be rotated smoothly.
The first annular member and the second annular member are joined by laser beam welding at radially outer ends thereof. Consequently, their joined and nearby areas are prevented from being deformed with heat and hence from being damaged, and it is possible to keep the dimensional accuracy of the outer race which has been achieved when the first and second annular members are produced by pressing.
The first annular member and the second annular member have respective portions joined to each other into the flange of the outer race.
The second annular member has the flange of the outer race, the first annular member having a radially outer end joined to a radially inner end of the flange.
The flanged ball bearing may further comprise a ring-shaped retainer disposed in the annular space and holding the balls out of contact with each other.
The first annular member may have a recess defined in a radially inner portion thereof, the ring-shaped retainer being insertable into and removable from the annular space through the annular space.
Each of the first annular member and the second annular member may be made of sheet steel pressed to shape.
The above and other objects, features, and advantages of the present invention will become apparent from the following description when taken in conjunction with the accompanying drawings which illustrate preferred embodiments of the present invention by way of example.
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“CB Flat Series”, Published by Eastern Seiko Co., Ltd., Brochure, 2 pages, (Dec. 1990).
“Product List of DBS Press Bearing Nos. 1 and 2”, Published by Daido Kogyo Co., Ltd., 2 pages, (Feb. 1984).
Hannon Thomas R.
Schwegman Lundberg Woessner & Kluth P.A.
TOK Bearing Co., LTD
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