Bearings – Rotary bearing – Plain bearing
Reexamination Certificate
2002-01-23
2003-08-12
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Plain bearing
C029S898020, C384S419000
Reexamination Certificate
active
06604859
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to oil film bearings of the type employed in rolling mills to rotatably support the journal surfaces of roll necks, and is concerned in particular with a novel and improved bushing that allows the bearings to remain mounted on and to serve as stable support platforms for the roll necks when the roll surfaces are being reground.
2. Description of the Prior Art
In the past, the prevailing practice has been to dismantle the oil film bearings from the roll necks prior to machining the roll surfaces. The exposed roll necks are then rotatably supported in fixtures specially designed to provide the extremely rigid bearing characteristics required for machining accuracy. During the time that the rolls are being machined and subsequently inventoried, the dismantled oil film bearings are remounted on spare rolls for reuse in the mill. To some extent, this practice is advantageous in that it results in a savings in capital investment which would otherwise be required if all rolls, including spare or replacement rolls, were to be provided with their own bearings. This advantage must, however, be viewed in the light of several disadvantages such as for example the time and effort expended by maintenance personnel in dismantling, removing and remounting the bearings, the possibility of the disassembled bearing components being damaged or contaminated with foreign matter, and the fact that the roll surfaces are not machined precisely concentrically with the bearings which will support them in the mill.
In order to obviate the above-mentioned disadvantages, an alternative practice has sometimes been adopted where the rolls are provided with their own sets of bearings that remain mounted on the roll necks while the rolls are in use in the mill and also while a machining operation is being performed on the rolls. This alternative practice has been found to be generally satisfactory, except for the fact that conventional oil film bearings are designed primarily for high-speed heavy-duty operations, and as such do not provide bearing characteristics at the low-speed low-load conditions of a machining operation that are as rigid and stable as the specially designed fixtures employed in the aforementioned prevailing practice. Thus, machining accuracy can be compromised.
SUMMARY OF THE INVENTION
In accordance with the present invention, the interior surface of the bearing's bushing is provided with secondary recesses positioned adjacent to the primary recesses or “rebores” into which oil is admitted to serve as a lubricant between the journal and bearing surfaces. The secondary recesses are narrower than the primary recesses, with both the primary and secondary recesses preferably being concave.
During a roll machining operation, the bearings and their respective chocks remain on the roll necks and are mounted in an appropriately designed support structure, with the bearings orientated to rotatably support the journal surfaces of the roll necks on the side edges of the bushing's secondary recesses. These side edges provide the rigid stable platform needed to achieve machining accuracy.
When the rolls are returned to service, the bearings are orientated such that the primary recesses operate in a conventional manner to introduce lubricant to the bearings load zones, with the edges of the secondary recesses no longer serving as supports.
REFERENCES:
patent: 2018055 (1935-10-01), Dahlstrom
patent: 3287072 (1966-11-01), Buske
patent: 3734580 (1973-05-01), Piscitelli
patent: 4023867 (1977-05-01), Piller
patent: 4038856 (1977-08-01), Bayer et al.
patent: 4291808 (1981-09-01), Roloff
patent: 4748729 (1988-06-01), Rochelmeyer
patent: 5009522 (1991-04-01), Hahn
patent: 5144828 (1992-09-01), Grotepass et al.
patent: 5720195 (1998-02-01), Ruple
Hannon Thomas R.
Morgan Construction Company
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