Infeed rolls

Since about 1990 the paddle or infeed rolls can also be driven separately, each from a slip-on type geared motor. Frequency control gives infinite variabihty of the paddle shaft speeds, so that these can be optimally adapted to the auger shaft speed (Fig. 38). 

Densification is accomplished by a 300 HP California Pellet Mill Model 7162-3. The pellets are formed by extrusion through nominally 3/8 inch diameter radial holes in a cylindrical die. Pressure is exerted on a "pad" of the material to be densified by rolls which have fixed shafts. The pellet die rotates about the pressure rolls. Pellet length is controlled by a "cut-off" knife positioned to clip the pellets as they exit the rotating die. The exiting material stream from the pellet mill is mechanically lifted to a pellet cooler, which discharges to a screen to remove under-size pellet pieces and fines. The fines and pieces are recycled to the pellet mill infeed system. Finished pellets are conveyed by high pressure air system to tank storage. 

Extrusion operations generate scrap in the form of thin strips of material from the edge of sheets or webs of material after thermoforming operations. Grinders for these applications typically incorporate powered feed rolls to assure consistent infeed of scrap material. 

---