Tapered auger shredder

An auger shredder comprising:

• a frame defining a grinding chamber having front and rear walls joined by downwardly-converging side walls, said fornt wall having a substantially centrally-located discharge opening, and a trough positioned beneath said side walls and inclined upwardly to said discharge opening;
• auger screw means for shredding material in said chamber and pumping said material through said discharge opening, said screw means being cantilevered from said rear wall and having a disc-shaped base plate rotatably mounted on said rear wall, a shaft centrally mounted on said base plate and extending through said grinding chamber to said discharge opening, and a helical flight extending along said shaft and having a first turn attached to and extending from said base plate about a circumference of said shaft, said first turn having a rear surface facing said rear wall;
• torque transmission collar means mounted on said base plate, attached directly to said rear surface of said first turn and extending substantially about an entire circumference of said shaft, for transmitting from said base plate more than 1 percent to approximately 15 percent of an overturning moment load, and more than 1 percent to approximately 20 percent of a torsional shock load to said first turn;
• and
• motor means for rotating said base plate and said screw.

An auger shredder comprising:

• a frame defining a grinding chamber having an open top for receiving material to be shredded, front and rear walls joined by downwardly-converging side walls, said front wall having a substantially centrally-located discharge opening, and a trough positioned beneath said side walls and inclined upwardly to said discharge opening;
• an extrusion tube mounted on said front wall and extending outwardly from said grinding chamber, said tube being concentric with and communicating with said discharge opening;
• auger screw means for shredding material in said chamber and pumping said material through said discharge opening, said screw means having a shaft rotatably mounted on said rear wall and extending through said grinding chamber and having a segment extending into said discharge opening, said shaft tapering along its length from said rear wall to said front wall, and a helical flight extending along said shaft and into said tube, said flight having an outer periphery which tapers in diameter from said rear wall to said front wall, said flight taper corresponding to said shaft taper such that a first series of pumping volumes, each defined by a segment of said shaft and a turn of said flight adjacent said segment outwardly to a periphery of said flight turn, are substantially equal to each other along a substantial portion of said length of said shaft in said grinding chamber, and another segment of said shaft and associated turn of said flight defines a second pumping volume, less than said first pumping volumes, in said tube;
• and
• motor means for rotating said auger screw, whereby compression of material by said screw means along said trough in said grinding chamber is substantially reduced to provide consistent flow of material to said discharge opening and reduce build-up of material at said discharge opening, and compression and particle size reduction of material occurs within said tube.

For use with an auger shredder having, a frame defining a grinding chamber for receiving material to be shredded, front and rear walls joined by downwardly-converging side walls, said front wall having a substantially centrally-located discharge opening, and trough positioned beneath said side walls and inclined upwardly to said discharge opening and including a plurality of breaker bars extending radially inwardly therefrom, an auger screw for shredding material in said chamber and pumping said material through said discharge opening comprising:

• a shaft adapted to be mounted on said rear wall and extend through said grinding chamber to said discharge opening;
• and shaft tapering in diameter along its length from said rear wall to said front wall;
• a helical flight extending along said shaft, said flight having an outer periphery which tapers in diameter from said rear wall to said front wall, said flight taper corresponding to said shaft taper such that a first series of volumes, each defined by a segment of said shaft and a turn of said flight adjacent to said segment, outwardly to a periphery of said flight turn, are substantially equal to each other along a substantial portion of said length of said shaft in said grinding chamber, so as to maintain a substantially constant volume along said length of said shaft;
• said flight including a plurality of teeth on and extending radially from a periphery thereof, said teeth being spaced to mesh with said breaker bars when said auger screw is fixed in an axial direction;
• and a leading edge shaped to pump material through said discharge opening;
• whereby rotation of said screw to pump materials along said trough minimizes compression of material and thereby provides consistent flow of material to said discharge opening of said associated grinding chamber.