Critical engineering problems are raised by the design of large screens above 12 sqm2. Some of these difficulties are the dynamic forces for which the mechanism has to be designed leading to very large bearings with low critical speeds.
The Mechanism
The mechanism consists of two counterweights, symmetrically assembled on one shaft. Each assembly consists of a very short, completely rigid shaft which permits the use of roller bearings with critical speeds higher that of ball bearings. The counterweights are keyed to those shafts with separate V-belt drives. Shaft and counterweight are in protective housing for oil lubrication and dust tightness.
Vibration
The mechanism of the ELLIVAR screen is located on the top of the frame. The motion of the vibration is not completely circular at each point. It is elliptical with the axis of the ellipse variable in an angle. The position of the mechanism was properly selected after considerable testing in order to create different functions for the various points on the screen. At the top the elliptical motion advances the feed rapidly. At the bottom of the screen the elliptical motion slows the material down to increase the screening efficiency.
The Frame
The frame is inclined like a conventional screen.
Bergeaud solved the problem by designing a counterweight screen which differs substantially from conventional designs. The forces are supported by 4 bearings.
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ELLIVAR SCREENS 16 AND 20 M2 COUNTERWEIGHT SCREEN WITH LARGE SCREENING SURFACES
Critical engineering problems are raised by the design of large screens above 12 sqm2. Some of these difficulties are the dynamic forces for which the mechanism has to be designed leading to very large bearings with low critical speeds.
The Mechanism
The mechanism consists of two counterweights, symmetrically assembled on one shaft. Each assembly consists of a very short, completely rigid shaft which permits the use of roller bearings with critical speeds higher that of ball bearings. The counterweights are keyed to those shafts with separate V-belt drives. Shaft and counterweight are in protective housing for oil lubrication and dust tightness.
Vibration
The mechanism of the ELLIVAR screen is located on the top of the frame. The motion of the vibration is not completely circular at each point. It is elliptical with the axis of the ellipse variable in an angle. The position of the mechanism was properly selected after considerable testing in order to create different functions for the various points on the screen. At the top the elliptical motion advances the feed rapidly. At the bottom of the screen the elliptical motion slows the material down to increase the screening efficiency.
The Frame
The frame is inclined like a conventional screen.
Bergeaud solved the problem by designing a counterweight screen which differs substantially from conventional designs. The forces are supported by 4 bearings.