NON-CIRCULAR ACCELERATION MECHANISM FOR A SINGLE SHAFT SCREEN
A single shaft material processing vibrating screen is described which provides for non-circular acceleration (elliptical and otherwise). The system includes a main eccentric is rotated a first direction and a secondary eccentric orbits the main eccentric in an opposite direction. The orbiting is accomplished by either long and short arms or by eccentric flywheels. The size and shape of elliptical/non-circular motion is adjustable by varying mass of main and secondary eccentrics, length of long and short arms or the size of eccentric flywheels.
1 . A method of screening material on a horizontal screen deck comprising the steps of:
providing a material processing screening plant with a first side, an opposing second side, an input end, a discharge end and a substantially horizontal screen deck disposed in a gap between said first side, said second side, said input end and said output end;
providing a rotatable shaft having a central axis that extends from said first side to said second side;
providing a first side weight moving mechanism coupled to a first end of said rotatable shaft;
providing a second side weight moving mechanism coupled to a second end of said rotatable shaft;
rotating said rotatable shaft and thereby causing a vibration of said substantially horizontal screen deck to propagate material disposed thereon so as to create a cumulative flow direction from said input end toward said discharge end; and
wherein said material processing screening plant is free of any additional rotatable shafts which extend from said first side to said second side.
2 . The method of claim 1 wherein said first weight moving mechanism comprises a weight which is caused to rotate around a first axis which is not said central axis.
3 . The method of claim 1 wherein said first weight moving mechanism comprises a weight which is caused to rotate around a first axis which is parallel with said central axis but displaced from said central axis.
4 . The method of claim 3 wherein said weight is caused to rotate by rotation of said rotatable shaft.
5 . The method of claim 4 wherein said first weight moving mechanism comprises a first long arm rotatably coupled so as to rotate about said central axis.
6 . The method of claim 5 wherein said first long arm is coupled to a first short arm which rotates around said first axis.
7 . The method of claim 6 further comprising the step of: adjusting a performance characteristic of said material processing screen plant by adding additional weight to said first short arm.
8 . A single shaft screening plant comprising:
a screen having a first side and a second side;
a rotatable shaft with a shaft axis, which extends from said first side to said second side;
a first side weight moving mechanism; coupled to a first end of said rotatable shaft;
a second side weight moving mechanism, coupled to a second end of said rotatable shaft;
said first side weight moving mechanism and said second side weight moving mechanism being, in combination, configured so that rotating said rotatable shaft causes a vibration which would increase an aggregate velocity vector of material on said screen in a direction toward a discharge end of said screening plant, if said screen were oriented substantially horizontally.
9 . The system of claim 8 wherein said first side weight moving mechanism comprises a plurality of connected rotating arms where one of said plurality of connected rotating arms revolves around said shaft axis and simultaneously rotates around a first axis which is parallel to and displaced from said shaft axis.
10 . The system of claim 8 wherein said first side weight moving mechanism comprises an internal gear.