Bearings – Rotary bearing – Antifriction bearing
Reexamination Certificate
2000-11-08
2003-03-25
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Antifriction bearing
Reexamination Certificate
active
06536953
ABSTRACT:
FIELD OF THE INVENTION
The invention relates reduction of vibration, and more particularly concerns a method and apparatus using a bearing mount system for reducing the vibration.
BACKGROUND OF THE INVENTION
Presently, a problem occurs with rotating rolls that operate near their natural frequency of vibration in that the vibration becomes excessive and the rolls do not run smoothly. In the textile fibers industry, this problem is of particular concern with a chuck for a textile fibers windup when the chuck is driven by contact with a drive roll contacting a package mounted on the chuck. As the package size increases, the speed of the chuck continuously decreases increasing the likelihood of encountering a natural frequency speed. In such a case, excessive vibration causes defects in the package as it “bounces” against the drive roll in its rotation. Some of these defects result in roundness and differences in package density or stiffness nonuniformity resulting in a package having mass unbalance further accentuating the problems of vibration.
For instance, in a plant facility where it was desired to make heavy denier packages on a windup having, for example, four chucks, the polymer delivery system could not deliver enough polymer to operate at full speed for the windup. The windup was then operated at less than full speed to accommodate the polymer supply, however, a natural frequency of the chuck was encountered, especially near the final package size, resulting in severe chuck vibration. Unfortunately, it was not possible to wind packages on the four chucks at the lowered speed. The force between the chuck and the drive roll affects this natural frequency, in that the frequency increases slightly with higher chuck forces. Generally, for good package formation and less machine wear, it is desirable to run with lower chuck forces. Operating only two of the four chucks (on one side of the winder) and running at a higher speed solved the vibrational problem, but productivity suffered. It is desired to find a way to reduce vibrations in chucks or similar rotating rolls without loss of productivity. It is also desired to reduce vibrations to make possible operation at lower speed on the chucks and at a lower chuck force.
The following disclosures may be relevant to various aspects of the present invention and are briefly summarized as follows: The Fafnir Bearing Company (now a division of the Torrington Co.) in a 1967 catalog (Catalog 68) offered a number of quiet bearing designs to reduce noise and vibration of standard ball bearings. On page 189 of the catalog, one design provided a U-shaped conductive rubber interliner that fit between the outer race and a pressed steel pillow block housing. The outer portions of elastomer were not contained and no design was offered for the inner race.
U.S. Pat. No. 2,244,197 shows a ball or roller bearing having a vulcanized rubber support for the inner race and for the outer race to reduce sound and vibration. The rubber supports may be vulcanized to their bed or pressed into it and they may be partially contained by shoulders on shafts or housings.
U.S. Pat. No. 5,295,744 shows a ball bearing for a drive shaft which has the inner race mounted to the shaft with a resilient means which in one embodiment comprises a double walled resilient annular member that may be filled with a settable elastomer or a damping fluid (FIG.
3
). In another embodiment (FIG.
4
), the support for the inner race is a resilient annular web that form-fittingly engages spaced O-rings, which help dampen vibration from the shaft. The elastomer is not rigidly contained axially.
U.S. Pat. No. 5,816,712 shows spaced elastomer rings sandwiched between metal cylinders that serves as a vibration attenuating mounting for the inner race of a ball bearing; a similar arrangement is also provided for the outer race. The spaced elastomer elements for the inner race are constrained axially by metal backing plates that have additional elastomer disks that axially engage the inner race.
SUMMARY OF INVENTION
Briefly stated, and in accordance with one aspect of the present invention, there is provided a mounting system for a rotary bearing having an inner raceway and an outer raceway, each having a mounting surface, used to support a rotating roll on a stationary support member, comprises: an annular groove adjacent the mounting surface of a raceway on the bearing, the raceway having shoulders on each end of the surface and the groove having a bottom with ends that are substantially aligned with the shoulders of the raceway and a land defining the top of the groove, with the land radially spaced from the raceway by a predetermined radial gap; a substantially enclosed cross-sectional area when the raceway mounting surface is concentric with the groove, the enclosed area defined by the groove bottom on one side, the raceway surface on an opposed side, and the groove ends, with the extension of the groove ends intersecting the raceway surface or an extension thereof at the gap, on the end sides; a singular annular member comprising an elastomer, the singular member mounted in the groove and contacting the bottom of the groove and the surface of the raceway, the singular member having a cross-sectional area that is contained within the enclosed cross-sectional area; an open area within the enclosed cross-sectional area that is free of singular member elastomer, the open area being 15% to 100% of a gap area comprising the product of the distance between the groove ends and the gap, so that when there is relative movement to reduce the distance between the surface of the raceway and the groove land which deflects the singular member elastomer and reduces the enclosed area, the open area is reduced or eliminated and the singular member elastomer viscoelastically deforms so that the mounting system provides a first rate of stiffness during the initial movement and a second rate of stiffness as the movement continues and before the radial deflection exceeds the radial gap, the second stiffness greater than the first stiffness.
Pursuant to another aspect of the present invention, a method for reducing the vibration of a rotating roll supported by a rotary bearing on a stationary support member, the bearing having an inner raceway and an outer raceway, each having a mounting surface, comprising: aligning a mounting surface of a raceway on the bearing adjacent an annular groove, the raceway having shoulders on each end of the surface and the groove having a bottom with ends that are substantially aligned with the shoulders of the raceway and a land defining the top of the groove, with the land radially spaced from the raceway by a predetermined radial gap; arranging the bearing surface concentric with the groove to define a substantially enclosed cross-sectional area, the enclosed area defined by the groove bottom on one side, the raceway surface on an opposed side, and the groove ends, with the extension of the groove ends intersecting the raceway surface or an extension thereof at the gap, on the end sides; partially filling the enclosed cross-sectional area with an elastomer material that contacts the bottom of the groove and the raceway surface; providing an open area within the enclosed cross-sectional area that is free of elastomer, the open area being less than or equal to a gap area comprising the product of the distance between the groove ends and the gap; resisting initial relative movement to reduce the distance between the surface of the raceway and the groove land by viscoelastic deformation of the elastomer material at least partially into the open area providing a first stiffness for reducing vibration, and resisting the relative movement during subsequent movement, before closing the radial gap, by viscoelastic deformation of the elastomer providing a second stiffness for reducing vibration, the second stiffness greater than the first stiffness.
Pursuant to another aspect of the present invention, a mounting system for a rotary bearing a rotary bearing having an inner raceway an
Cope Steven A.
Kennard Jeffrey L.
Lamontia Mark A.
E. I. du Pont de Nemours and Company
Hannon Thomas R.
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