Classifying – separating – and assorting solids – Sifting – Plane sifters
Reexamination Certificate
1999-03-22
2002-02-19
Jillions, John M. (Department: 3653)
Classifying, separating, and assorting solids
Sifting
Plane sifters
C411S371100, C411S542000
Reexamination Certificate
active
06347708
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to vibratory devices such as vibrating screens for classifying aggregate and vibratory feeders for feeding aggregate to crushing and processing devices. More specifically, the present invention relates to an improved wheel case for housing the rotating components of the vibratory devices and for protecting those components from the loss of lubricant and/or from the ingress of contaminants.
BACKGROUND OF THE INVENTION
Vibrating screen devices and vibrating feeder devices are generally well known in the art. On a typical vibrating screening device, a system of classifying screens are mounted to a frame which in turn is supported on a system of springs. At or near the center of the device is an eccentrically weighted shaft unit, typically having one, two, or three or more rotating and eccentrically weighted shafts. On a multi-shaft unit, the shafts may be counter-rotating such that the eccentric weights are oriented in the same direction twice each revolution. This causes the screen to vibrate, which aids the classifying effects of the screen device. On a vibrating feeder, a similar shaft unit vibrates the feed trough or chute, which “throws” the aggregate contained in the trough in a desired direction. An example of such a device can be found in U.S. Pat. No. 4,340,469 issued to Archer.
The ends of the rotating shafts are supported by bearings, and each shaft includes a drive wheel or gear. The shaft drive gears are operatively coupled to an external drive motor. The eccentric weights are typically attached to the ends of the shafts adjacent the drive wheels. The bearings and the drive wheels require constant lubrication, and thus such components are disposed within a wheel housing or case containing a quantity of oil or other suitable lubricating fluid. The wheel case is typically bolted to the frame of the vibratory device.
Historically, conventional cap screws have been used to secure the wheel case to the frame of the vibratory device. However, due to the constant vibration, coupled with the constant exposure of the cap screws to the lubricating oil, such conventional cap screws are subject to loosening. The loosened cap screws provide a convenient avenue for oil loss, and also provide a convenient avenue for the ingress of dirt, water, and other contaminants. Moreover, the cap screws are not readily accessible for the purposes of re-tightening.
Accordingly, threadless fasteners have been used, such as the threadless fastener sold under the trade name Huckbolt® manufactured by the Federal Mogul Corporation. Such a fastener has a threadless collar that is pressed onto the bolt shank using hydraulic means. The collar engages a series of annular rings spaced along the bolt shank. Such bolts typically provide consistent clamping force and exhibit high resistance to loosening in most applications. However, such bolts may experience loosening when used in highly lubricated, vibrating environments, thus leading to the leakage problems outlined above. Such bolts are not easily re-tightened, and as outlined above, it is not easy to access the securing bolts in any event.
In addition to the problems with oil loss and contaminant ingress, both of which lead to premature failure of the gears and/or the bearings housed within the wheel case, a loose bolt also causes the holes through the bolted components to enlarge, thus accelerating the loss of oil or the ingress of contaminants. Moreover, loose bolts permit small pieces of aggregate to become lodged between the various bolted components, rendering it impossible to securely bolt the components together without completely disassembling and cleaning the device.
A similar leakage problem may be created where the spindles, which support the rotatable shafts, are secured to the frame. The spindles are typically disposed within the wheel case such that the shaft bearings are exposed to a constant supply of lubricating oil. Each spindle includes a mounting flange, and an O-ring seal may be provided under the mounting flange. However, the cap screws used to secure the spindle to the frame may loosen in a manner similar to the problem described above, leading to similar problems.
As mentioned above, at least one of the shafts is operatively coupled to an external drive system. Typically, one of the shafts is extended through the wheel case cover for connection to a drive motor. This penetration through the wheel case must be sealed. Due to deflections at the end of the shaft caused by the extreme operating conditions, the end of the shaft typically experiences “runout” which typically causes premature breakdown of the seal. Although labyrinth seals have been employed, a typical labyrinth seal includes a weep hole for captured oil to escape back into the sealed area. Under the extreme operating conditions of the wheel case, in which the rotating eccentric weights contact the oil supply at velocities in excess of 5000 feet per second, the resulting oil agitation throws oil through the weep hole, causing lubricant loss. Consequently, the seal becomes one additional path of lubricant loss or contaminant ingress.
Accordingly, an improved wheel case having an improved fastening system less prone to loosening and leakage is desired. It is also desired to have an improved wheel case which exhibits better lubricant retention characteristics than prior art wheel cases.
SUMMARY OF THE INVENTION
According to one aspect of the invention, and for use with a vibratory device for vibrating aggregate material, the device having a frame and a rotating shaft extending transversely across the frame, the shaft having a wheel, a sealed wheel case comprises a housing having a base, a peripheral sidewall, and a cover. The housing is sized to receive therein the wheel and is further adapted to house therein a quantity of lubricating oil for lubricating the wheel. A plurality of attachment bolts are provided for securing the housing to the frame. Each of the attachment bolts includes a shank, an inner end disposed within the wheel case and having an inner contact surface, an inner control washer disposed between the inner contact surface and the housing base, with the inner control washer having a first predetermined thickness. The inner control washer includes an aperture therethrough sized to form with the bolt shank an annular cavity, and an O-ring is provided which is sized for insertion in the annular cavity, with the O-ring having a second predetermined thickness greater than the first predetermined thickness. The bolt further includes an outer end disposed outside the wheel case and having an outer contact surface adjacent the frame. Accordingly, in response to securement of each attachment bolt each O-ring is compressed to substantially fill its adjacent annular cavity, thereby preventing the lubricant from escaping the housing.
In further accordance with a preferred embodiment, the second thickness is approximately thirty percent (30%) greater than the first thickness. Still preferably, the first thickness is approximately 0.11 inches, and the second thickness is approximately 0.14 inches. Each attachment bolt is preferably a non-threaded huckbolt.
In further accordance with a preferred embodiment, the second thickness is approximately thirty percent (30%) greater than the first thickness. Still preferably, the first thickness is approximately 0.11 inches, and the second thickness is approximately 0.14 inches. Each attachment bolt is preferably a non-threaded fastener having a pressed on collar, such as a Huckbolt®.
According to another aspect of the invention, a sealed attachment bolt is provided for securing the base of a sealed housing to a frame, with the housing being adapted to hold a quantity of lubricant. The attachment bolt comprises a shank, an inner end disposed within the housing and having an inner contact surface, and an inner control washer disposed between the inner contact surface and the housing base. The inner control washer includes a first predetermined thickness and further includes an
Cedarapids Inc.
Jillions John M.
Marshall Gerstein & Borun
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