Bearings – Linear bearing – Roller bearing
Reexamination Certificate
1999-10-25
2001-08-28
Hannon, Thomas R. (Department: 3682)
Bearings
Linear bearing
Roller bearing
C072S250000, C384S373000, C384S380000, C384S418000, C492S001000
Reexamination Certificate
active
06280087
ABSTRACT:
FIELD OF INVENTION
This invention relates to a guide for a steel mill wherein a pair of rotating rollers receive and guide a steel work product therebetween so that the work product is maintained in a predetermined orientation for the entry to the bite of the next set of processing rollers.
BACKGROUND OF THE INVENTION
Roller guide assemblies are required in order that the material being processed by the mill arrives at the next set of reducing rollers in the proper orientation and any unwanted twisting of the material being reduced is prevented. Because mill operators are constantly under pressure to increase the output of an operating mill, the speed at which the material undergoing reduction continues to increase. Thus, if a billet is passed through a multi-stage reducing mill at ever increasing speeds, the last set of reducing rollers and the associated mill guides must be capable of rotational speeds to match the speed of the material exiting from the last reducing rollers.
The rollers in the guide usually have a predetermined shape to assure that the previously shaped material is grasped between the opposing guide rollers in a specific orientation to assure that the moving material is passed into the bite of the next set of rollers in a specific orientation. The rollers are usually mounted on bearing assemblies to enable the rollers to continuously rotate at fairly high speeds while sustaining substantial thrust due to the pressing engagement with the moving material. Because the rollers must rotate in an environment which may be best described as hostile, any suggestion of a mill operation, wherein the throughput is to be substantially increased by increasing the speed of the material being reduced, will be met with resistance and cynicism by mill designers. Because the material being reduced is hot, the rollers must be cooled in some manner to obtain a satisfactory bearing life for the bearings in the roller. The lead end of the material being reduced, may at times, strike one of the guide rollers upon entry to the guide causing a permanent scar on the surface of the roller and simultaneously cause a spike load on the bearing elements themselves which may cause a shortening of the life of the bearing.
It would seem obvious that the designers of steel mills could extend the life of the various components of the mill especially the guide members by decreasing the loading on the guide rollers and their bearings by the utilization of larger more robust rollers mounted on suitable bearings. Of course this avenue is not available because of the limited space available for the guide in the space between the rollers of each reducing stage. Thus, it is necessary to keep the roller diameter within certain prescribed limits to mount the guide as close to the roller byte as possible.
SUMMARY OF THE INVENTION
The guide of this invention utilizes a pair of guide rollers fabricated of ceramic or other suitable material which are capable of rotational speeds previously deemed impossible. Each roller is provided with a grooved peripheral surface to engage the material passing therebetween in a positive manner so that the material is maintained in a preferred orientation for entrance to the next set of reducing rollers, and each roller is provided with a frusto-conically shaped cavity which extends along the axis of each roller.
The cavity is in communication with a central bore in each roller which extends through the roller. At the surface where the bore exits the roller, a tapered funnel shaped surface is provided for receiving a spherical ball.
Each roller is mounted in the guide so that the frusto-conically shaped cavity receives a correspondingly frusto-conically shaped projection which forms the basic bearing structure for the roller. The projection and cavity will operate to have a space formed therebetween to establish an oil film between the two surfaces. The projection is formed from a hard substance such as tungsten carbide. The projection is supplied with oil under pressure which is fed into the bearing film area by means of a co-axial bore in the frusto-conical projection which is in communication with the space between the roller and the projection.
Some oil also passes through a bore provided in each roller to provide some lubrication to the ball seated in the recess in the top surface of the roller. The roller assembly is held in an operating position by means of a removable housing (to permit roller replacement) which becomes part of the guide assembly.
The removable housing is supplied with a small bearing which controls the pressure of the spherical ball on its mating surface with the roller and thus, provides the restriction and pressure release for the pressurized oil in the roller-projection interface.
PRIOR ART
U.S. Pat. 4,373,367 Feb. 15, 1983
FIG. 3 of this patent illustrates the construction of the bearing system of a typical roller assembly of a prior art steel mill rolling guide. In it, a shaped roller is mounted on the outer races of a pair of spaced apart ball bearings. The inner races of the ball bearings are mounted on a massive bolt secured in the guide housing. This construction is typical of most roller guides in use today.
REFERENCES:
patent: 1278398 (1918-09-01), Thornton
patent: 3552805 (1971-01-01), Dunlap
patent: 4039107 (1977-08-01), Boley
patent: 4373367 (1983-02-01), Fabris
patent: 4562976 (1986-01-01), Ban
patent: 4876875 (1989-10-01), Bruggeman et al.
Hannon Thomas R.
Oldham Edward H
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