Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
1999-08-27
2001-07-10
Footland, Lenard A. (Department: 3682)
Bearings
Rotary bearing
Plain bearing
C384S207000
Reexamination Certificate
active
06257767
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to a bearing retainer that holds a bearing in place in a bearing seat of an electromagnetic device where the bearing retainer has a unique construction that reduces its cost of manufacture. More specifically, the present invention pertains to a bearing retainer having a flanged shaped outer peripheral edge with a plurality of radially extending tabs centered in gaps in the peripheral edge. The flanged shape of the peripheral edge enables the retainer to be bowl/track fed in automated assembly of the retainer into a housing and the tabs connect with tabs of adjacent bearing retainers, allowing optimization of material consumption and reducing costs in the stamping process. In the preferred embodiment, the bearing retainers are composed of a pre-tempered steel, for example Martinsite®, thus eliminating a subsequent heat tempering process required of prior art retainers and further reducing the cost of manufacture.
2. Description of the Related Art
A bearing retainer is employed to retain a bearing supporting a rotating shaft of a device in a bearing seat on an enclosure end wall of the device. An example of such a bearing retainer is described in the U.S. Pat. No. 4,910,424, of Borcherding, which is assigned to the assignee of the present invention and is incorporated herein by reference.
The prior art bearing retainer disclosed in the above referenced patent is manufactured by stamping the retainer from a strip of steel. The stamped retainer has a center hole, defined by a circular inner edge of the bearing, and a circular outer perimeter. The bearing has an intermediate ring section between the inner edge and the outer perimeter of the bearing. The ring section is generally flat and is pressed flat against a mating surface or surfaces of the device enclosure end wall when inserting the retainer against a bearing positioned in the bearing seat of the end wall. The outer perimeter edge of the retainer is formed at an angle relative to the intermediate ring section of the retainer. This provides a chamfer or tapered edge around the outer perimeter of the bearing retainer that is press-fit into an annular cavity or shoulder of the device enclosure end wall to securely hold the bearing retainer in position in the end wall. A plurality of resilient fingers project radially inwardly from the inner edge of the bearing retainer into the retainer center hole. The fingers are also angled relative to the intermediate ring section of the bearing. The resilient fingers engage against the outer surface of the bearing mounted in the bearing seat of the device enclosure end wall and hold the bearing in the bearing seat.
As stated earlier, prior art bearing retainers of this type are manufactured by stamping the bearing retainer from a strip of steel. In the stamping process, the bearing retainer is cut out from the strip of steel in its final configuration and is simultaneously formed with its tapered outer edge and with the plurality of angled, resilient fingers spatially arranged around its inner edge. Subsequent to the stamping process, the bearing retainer is heat tempered to increase its strength. Although the bearing retainer of the prior art functions well for its intended purpose, it could be improved upon if its manufacturing costs are reduced.
SUMMARY OF THE INVENTION
The present invention provides a bearing retainer with a unique construction that reduces its manufacturing cost over that of prior art bearing retainers. Like the prior art bearing retainer, the bearing retainer of the invention is stamped from a strip of steel. However, the bearing retainer of the present invention is stamped from pre-tempered steel, for example Martinsite®. The use of Martinsite® in the bearing retainer of the invention provides it with sufficient strength and enables the elimination of the subsequent heat treating step required of prior art bearing retainers, thus reducing its manufacturing cost.
The stamped bearing retainer of the invention has a generally circular configuration with a center hole defined by a circular inner edge of the bearing retainer. Surrounding the inner edge of the bearing retainer is a ring portion of the retainer. The ring portion is stamped with a flat surface. Radially outwardly from the ring portion of the retainer the bearing retainer is formed with several arcuate flanges. In the preferred embodiment there are three arcuate flanges. The arcuate flanges have orientations that angle away from the planar surface of the bearing ring as they extend outwardly from the bearing ring. The three arcuate flanges define the outer perimeter of the bearing retainer. Providing the flanges on the retainer periphery enables the retainers to be bowl/track fed in automated assembly of the retainer into housings. The flanges reduce the possibility of adjacent retainers “leafing” or “shingling” over each other in the tracking of the bowl feeders. The arcuate flanges also serve to locate and center the retainer during assembly into the housing enclosure to ensure proper bearing retention.
The three arcuate flanges are separated from each other by gaps formed in the outer perimeter of the bearing retainer. The gaps are formed by pairs of notches cut into the perimeter of the bearing retainer in the stamping process and radially projecting tabs positioned between the notches of each pair. The tabs project radially outwardly from the ring portion of the bearing retainer and are preferably coplanar with the planar surface of the ring portion. The tabs function as the interconnecting tabs or trim tabs that connect adjacent bearing retainers following the stamping process and enable the nesting of the retainers diagonally across a strip of steel further reducing manufacturing costs.
As in the prior art bearing retainer, the bearing retainer of the invention is also formed with a plurality of resilient fingers that project radially inwardly toward the center of the bearing retainer center hole from the retainer inner edge. The resilient fingers have an angled orientation relative to the planar surface of the retainer ring just as in the prior art retainer.
The bearing retainer of the invention is formed with arcuate ridges that project from the inner edge of the retainer. The ridges are positioned opposite the gaps in the outer perimeter of the retainer and reinforce the retainer ring portion in the area of the gaps. The ridges have angled orientations relative to the planar surface of the retainer ring portion, and in the preferred embodiment are formed at right angles relative to the planar surface of the ring portion. The arcuate ridges are not limited to right angles. However, the right angles optimize the retainer strength and enable a maximum flow of injectable lubricant from one side of the retainer to the other. The resilient fingers and arcuate ridges are spatially arranged relative to each other around the inner edge of the bearing retainer ring.
The bearing retainer of the invention is used in the same manner as prior art bearing retainers. The bearing retainer is press-fit into an annular shoulder provided for the retainer in the enclosure end wall in which the bearing is mounted. The resilient fingers of the bearing retainer engage against a back side of the bearing and secure it firmly in the bearing seat of the enclosure end wall. The arcuate ridges on the inner edge of the bearing retainer reinforce the retainer in the area of the gaps and prevent the retainer ring portion from bending in the area of the gaps when the retainer is press-fit into the annular shoulder of the enclosure end wall. The tapered configurations of the arcuate flanges at the perimeter of the bearing retainer provide a tight friction fit of the bearing retainer in the annular shoulder of the enclosure end wall in the same manner as the circular flange of the prior art bearing retainer. However, to compensate for any reduction of the interference fit resulting from segmenting the arcuate flanges by the gaps between the flanges
Borcherding Gary W.
Leicht Jeffrey K.
Emerson Electric Co.
Footland Lenard A.
Howell & Haferkamp LC
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