Hydrodynamic Thrust Bearing Assembly

This invention relates to an improved bearing assembly including an internally grooved bearing sleeve and a slotted thrust plate or button, capable of accommodating both radial and axial forces such as are exerted on a rolling machine roll, for example a tension leveler roll, and replaces more expensive roller bearings.

Cylindrical sleeve bearings are known to the prior art, including such bearings having spiral grooves therein, or in a supported rotating shaft, for distribution of lubricating oil to the bearing, for example U.S. Pat. Nos. 1,377,866, wherein two-side surfaced troughs are cut, e.g. spirally, into a bearing b mounted about a rotating shaft c. Lubricating oil is introduced into grooves a and, from the grooves, into the abutting surfaces of bearing b and shaft c. In U.S. Pat. No. 3,942,847, an expandable, helically grooved ceramic member 1 is disposed between a rotating shaft and a cylindrical bearing and expands or contracts with changes in temperature. U.S. Pat. No. 4,427,308 shows a bearing assembly in which sprial grooves 54 are cut into a journal portion 48 of a shaft 46 mounted within a cylindrical bearing 36 provided with thrust washers 26 and wherein the grooves 54 serve to distribute lubricating oil between the rotating surfaces. U.S. Pat. No. 4,459,048 relates to an oil film bearing in a rolling mill and in which an oil film is maintained between a rotating bearing bushing 8 and a fixed bushing 12 by means of spirally disposed grooves 15 in the rotating bushing. U.S. Pat. No. 5,096,309 is directed to a hydrodynamic bearing system, for a laser printer or the like, in which a grooved shaft 1 is rotatably mounted in a sleeve 2 having an end plate 2b on which a resinous thrust plate 33 is mounted. An opening 7 and grooves 11 in the thrust plate enable the recirculating flow of a lubricating fluid through the grooves on the shaft 1 and between the shaft and the sleeve 2.

The bearing assembly of the invention is useful in the support of the necks of rolls in a rolling apparatus, especially the rolls of a tension leveler. For such purpose, there is provided a bearing subassembly and comprising a hollow cylindrical bearing sleeve mounted about the roll neck and provided, on an interior surface thereof, with helical grooves surrounding the roll neck. A cylindrical bearing thrust plate or button, preferably formed of a graphite or graphite/metal composition, and having a central aperture, abuts the reduced diameter end of the bearing body and is provided with a plurality of radially extending slots. These subassembly elements are held in place by means of a hollow cylindrical cap provided with an aperture communicating with the aperture of the bearing button and with the radial slots of the bearing button. A process fluid, for example air, is introduced through a connecting pipe to the cap aperture, and flows into the button aperture and thence through the radial slots of the button and into the helical grooves of the cylindrical bearing sleeve to cool and/or lubricate the abutting rotating surfaces.

Optionally, in order to accommodate short rolls or rolls of differing diameters, e.g. in the retrofitting of existing rolling machines, there may be provided a cylindrical roll-extension member, one end of which is secured, by appropriate known means, to the roll neck and the other end of which is of reduced diameter and about which the bearing assembly, specifically the hollow cylindrical bearing sleeve is mounted.

FIG. 1 is a side or plan view of one form of the inventive bearing;

FIG. 2 is an end view of the thrust button taken along line A-A of FIG. 1, and

FIG. 3 is a side view of the button shown in FIG. 2.

In FIG. 1, the numeral 1 denotes generally a roll of a rolling apparatus, for example, a roll in a tension leveller, having a reduced diameter neck 2. In one form of the invention, there is connected to the neck 2 a roll-extension member comprising a cylindrical roll-extension member 4 having a reduced end portion 6 and rotatable with the roll 1. A bearing assembly denoted generally by the numeral 3 comprises a hollow cylindrical bearing sleeve 7 on an interior surface of which there is provided a helical or rifled groove 8 extending along the length of the sleeve 7 which is mounted, in a non-rotating manner, about the reduced end portion 6 of the rotatable body 4. Alternatively, the helical groove 8 may be formed on the reduced diameter end portion 6 of the member 4, or the member 4 may be eliminated and the bearing assembly similarly mounted about the roll neck. The latter would normally be the case in installation of new rolling machines.

An end thrust plate or button 9 is mounted against the end of the roll neck or of the reduced end portion 6 of the body 4 and is provided with a central aperture 11 and a plurality of straight grooves or slots 12 extending radially outwardly of the central aperture 11 (FIGS. 2 and 3).

Subassembly elements such as elements 7 and 9 preferably are made of a composition comprising graphite, a graphite/metal composition or combinations thereof, for example, particularly useful composition are those comprising a graphite/metal composition produced by Pure Carbon Company, a division of Morgan Advanced Materials and Technology, Inc., of St. Marys, Pa., and sold under the designations P-3310 and P-658 RCH.

A cylindrical cap 13, e.g. made of a suitable steel, and having a central aperture 14, holds in place the hollow cylindrical bearing sleeve 7 and the button 9 with the apertures 14 and 11 in registration with each other and, through aperture 11, communicating with radial slots 12 and helical groove 8.

In operation, a cooling and/or lubricating fluid, e.g. air, is introduced through a supply pipe 16 and flows through aperture 14, aperture 11, slots 12 and groove 8 thereby cooling the abutting surfaces of the cylindrical bearing sleeve 7 and the rotating roll neck 2 or the reduced diameter portion 6 of the member 4, and also the abutting surfaces of the button 9 and the end of the rotating roll neck or of the reduced diameter portion 6 of member 4.

A bearing design and construction as above shown and described effectively absorbs both radial and axial thrust forces from the associated roll and helps to reduce the thrust forces between those opposed rotating surfaces. Due to the effect of the applied process fluid in the manner shown and described, the present invention can replace much more expensive ball bearing assemblies which normally have a useful life of only about 200 hours.