Bearings – Rotary bearing – Fluid bearing
Reexamination Certificate
1999-07-13
2001-03-20
Hannon, Thomas R. (Department: 3682)
Bearings
Rotary bearing
Fluid bearing
C384S117000, C384S247000, C384S310000
Reexamination Certificate
active
06203202
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention is directed to a method for monitoring and controlling the operation of rotary drums borne on sliding blocks such as, for example, tube mills, rotary tubular kilns, etc., that are seated on sliding block shoes charged with compressed oil. The invention is also directed to a sliding block bearing for such rotating drums
It is known to bear large, heavy rotary tubes such as, for example, tube mills on a plurality of sliding block shoes that are arranged distributed around the lower rotary tube circumference and are operated hydrostatically and/or hydrodynamically, whereby the rotary tube bears on cushions of compressed oil that is pressed into the lubricating gap between the sliding block shoes and the supported running surface of the rotating drum. For monitoring the operation of the sliding block bearing via a temperature sensor, only the temperature of the compressed oil flowing off from the sliding block was hitherto measured. When the thickness of the compressed oil film carrying the rotary tube or, respectively, the thickness of the lubricating gap becomes too small during operation, the compressed oil heats. During operation of such tube mills borne on sliding blocks, the temperature sensor for the compressed oil was therefore already used to output an alarm signal upon upward transgression of a compressed oil temperature of, for example, 90° C. and to shut the tube mill off when an even higher, maximally allowed compressed oil temperature is upwardly exceeded. Further, the pressure and the flow through quantity of the compressed oil guided in the circulation have been measured by utilizing a pressure monitor and a flow-through monitor.
The measured quantities of temperature, of pressure as well as the flow-through amount of the compressed oil, however, are not necessarily representative of the conditions at the sliding block, particularly for the thickness of the lubricating gap that is present thereat or not present thereat. In particular, the measuring point for the pressure as well as the flow-through quantity of the compressed oil are necessarily at a great distance from the actual location of occurrence, namely from the sliding block supporting surface, if only for spatial reasons. Added thereto is that the measured result of the temperature sensor, of the pressure monitor and/or of the flow-through monitor for the compressed oil has great inertia. At any rate, whether the lubricating gap at the hydrostatically and/or hydrodynamically operated bearing block is adequately large or even zero during operation of a tube mill seated on sliding blocks, could previously not be identified with certainty.
SUMMARY OF THE INVENTION
In rotating drums such as, for example, tube mills, the invention is therefore based on the object of monitoring the function of the sliding block bearing elements in view of the thickness of the hydrostatically and/or hydrodynamically generated compressed oil film or, respectively, compressed oil cushion and controlling the operation in conformity with the result of the monitoring.
For dependable operation of a rotating drum seated on sliding blocks, the crux of the invention is to directly measure the thickness of the lubricating gap during operation, i.e., the distance between the sliding block bearing surface and the rotating drum supported thereon via the lubricating gap or, respectively, the running surface thereof, and to control the operation of the rotating drum dependent on this measured quantity. Primarily, it is inventively identified whether a measurable compressed oil film or, respectively, a compressed oil cushion is present at all at the sliding block bearings. When yes, the rotary tube drive can be started and, for example, the tube mill can be accelerated. When the direct measurement of the lubricating gap yields a measured quantity of zero, the operation of the rotary tube is shut down. In addition to this monitoring and control, the thickness of the compressed oil film when a compressed oil film is identified as being present can also be determined in absolute numbers as a secondary measured quantity and, thus, the height of the lift affected by the sliding block shoes charged with compressed oil can also be identified.
For realizing the direct measurement of the thickness of the lubricating gap, at least one sensor is arranged at each sliding block bearing element of the rotary tube, this at least one sensor directly measuring the thickness of the lubricating gap, i.e., the distance between the bearing surface of the sliding block shoe and the running surface of the rotating drum supported thereon via the lubricating gap or, respectively, pressurized oil film. Inventively, the sensor is an electronic measured value sensor, preferably with an inductively or capacitatively generated measured signal. For obtaining a representative measured value, two sensors are provided per element of the sliding block shoe, namely a sensor in the admission region and a sensor in the discharge region of the sliding block bearing element. According to a particular feature of the invention, even three sensors can be arranged per element of the sliding block shoe, namely a sensor roughly in the center in the admission region and two sensors roughly in the comers of the discharge regions of the sliding block shoe element, as a result whereof the spatial distance allocation of bearing surface of the sliding block shoe and running surface of the rotating drum can be monitored and measured and a potential tilt of monitored sliding block shoes can be identified.
REFERENCES:
patent: 4032199 (1977-06-01), Jenness
patent: 4512671 (1985-04-01), Giers et al.
patent: 4643592 (1987-02-01), Lewis et al.
patent: 5397183 (1995-03-01), Lu et al.
Hagedorn Alexander
Troeder Christoph
Hannon Thomas R.
KHD Humboldt Wedeg AG
Sonnenschein Nath & Rosenthal
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