Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2000-08-17
2001-10-09
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
C384S585000
Reexamination Certificate
active
06299359
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a bearing assembly with locking collar for use on rotatable shafts.
BACKGROUND OF THE INVENTION
Bearing assemblies with locking collars are known in the art. A problem with these devices is that when mounted on rotatable shafts they generate excessive vibration and noise during use. These bearing assemblies also mar the rotatable shafts. In an attempt to reduce the vibration and noise from the bearing it has been necessary to keep the bearing dimensions to close tolerances. It has also been necessary to keep the shaft true and round to similarly close tolerances. Furthermore, different means to secure the bearing to the shaft have been tried in attempts to reduce the noise and vibration, and to reduce marring of the shaft.
One such means to secure the bearing to the shaft includes the use of a locking collar and slotted axial extensions, or fingers, extending out from the inner race member of the bearing. These bearing assemblies are secured to a shaft by the locking collar that applies a force to the slotted axial extensions. The slotted axial extensions in turn grip the rotatable shaft. Different designs of slotted axial extensions and locking collars have been tried.
One such locking collar arrangement uses a screw having two different thread diameters to increase the force applied to slotted axial extensions extending from the inner bearing race. The locking collar is a two-piece device secured by tightening screws that are spaced 180° apart. Both collar pieces have internal threads with one collar piece accepting a part of the screw having one diameter, and the other collar piece accepting that part of the screw having the different thread diameter. The slotted axial extensions have a raised end portion defining a groove between the slotted axial extensions and the locking collar. Because of this groove, the locking collar only contacts the end portion of the slotted axial extensions. In order to secure a bearing assembly in a concentric position with respect to the rotatable shaft, both screws must be tightened to the same extent.
In one such slotted axial extension arrangement, the slotted axial extensions have a raised end portion that defines a recessed annular groove between it and the locking collar. The end portions of the slotted axial extensions are of sufficient breadth and depth to convert what would otherwise be a shearing force to a bending force, thus, apparently, improving the bearing's ability to handle radial torque and thrust.
Another locking collar arrangement makes use of a tapered adapter and an extension from the inner bearing race. The exterior surface of the tapered adapter and the interior surface of the inner bearing race, and its extension, have complimentary tapers so that the tapered adapter fits between the bearing with extension and the rotatable shaft. The extension is threaded and accepts a threaded locking collar. There is a further groove defined in the outside diameter of the extension that accepts a corresponding lip in the leading edge of the threaded locking collar. The locking collar attaches to the tapered adapter and bearing. The locking collar then must be tightened onto the threaded extension so as to drive the tapered adaptor between the extension and rotatable shaft and engage the groove on the extension in order to secure the bearing assembly to the rotatable shaft.
Yet another locking collar arrangement employs a compressible locking ring together with a tapered adapter and an extension from the inner bearing race. Similar to the device described above, the exterior surface of the tapered adapter and the interior surface of the inner bearing race, and its extension, have complimentary tapers so that the tapered adapter fits between the bearing with extension and the rotatable shaft. The extension is threaded and accepts a threaded locking collar. In this device, however, the compressible locking ring fits into a groove in the tapered adapter. The locking collar has internal threads that engage external threads on the tapered adapter. The locking collar also has a groove that accommodates the top of the compressible locking ring. The procedure to secure the bearing assembly to the rotatable shaft is similar to that described above, but with the further step of attaching the compressible locking ring to the groove in the tapered adaptor.
One bearing assembly uses radially acting screws in a locking collar to press down on a tapered extension from the bearing inner race member. The inside diameter of the tapered extension is the same as the diameter of the inner race member that fits around the rotatable shaft. The outside diameter of the extension is tapered either towards the inner race member or away from it. The radially acting screws are spaced around the locking collar and when tightened bind down on the extension. Every radial screw must be properly tightened to secure a bearing assembly to a shaft using this locking collar arrangement. Also. to secure the bearing assembly in a concentric relationship to the shaft each radial screw must be tightened to the proper extent.
Another bearing assembly employs a threaded extension from the inner race member and a threaded locking collar as part of the means to secure the bearing to a rotatable shaft. The locking collar has an inside flange. A wedge ring and conical washer are interposed between the locking collar and the end of the extension. The wedge ring has a thick portion and thin portion. The extension has a tapered end section that accepts the wedge ring, with the thick portion of he wedge ring extending slightly beyond the end of the extension. The conical washer abuts the thick portion of the wedge ring and the locking collar flange presses up against the conical washer. By tightening the locking collar, the conical washer presses the wedge ring between the extension and rotatable shaft thereby securing the bearing assembly to the rotatable shaft. To secure a bearing assembly to a shaft using this locking collar arrangement each component must be properly assembled.
Each of the above devices for securing a bearing assembly to a shaft has to some extent proven unreliable or cumbersome. Each of these devices requires numerous steps to secure the bearing assembly to a rotatable shaft using the locking collar. None of these devices provides means to readily compensate for irregularly shaped shafts or shafts of a nominal diameter but having a range of different dimensional tolerances. This can lead to bearings that are not truly secured to the rotatable shaft or to bearings that are not mounted concentrically. Both situations may cause the device in which the shaft functions to operate with excessive noise or vibration. Both situations may also lead to damage of the shaft, or the device in which the shaft functions.
What would therefore be advantageous is a bearing assembly and locking collar that has fewer assembly steps than the prior art devices. It would be further advantageous to have a bearing assembly and locking collar that readily secures a bearing to a rotatable shaft. It would be yet another advantage to have a bearing assembly and locking collar that could readily accommodate irregular shafts and variations in shaft tolerances. It would be still another advantage to have a bearing assembly that reduces marring of a rotatable shaft when mounted on the shaft.
SUMMARY OF THE INVENTION
The present invention provides a bearing assembly and locking collar that accommodates shafts having irregular diameters or variations in diameter tolerances while maintaining a high degree of concentricity with respect to the rotatable shaft. Furthermore, the present invention provides a means to lock a bearing assembly onto a rotatable shaft and thereby reduce noise and vibration that might otherwise occur with use of the device containing the rotatable shaft. The present invention also provides a means to lock a bearing assembly onto a rotatable shaft and thereby reduce marring of the shaft.
The present invention provides a bea
AMI Bearings, Inc.
Gardner Carton & Douglas
Hannon Thomas R.
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