Quill shafted pellet mill

Abstract

The present invention employs a main shaft cantilevered from a frame. A die holder is disposed around the outside of the shaft, and in the preferred embodiment rotates by the use of adjustable tapered roller bearings around the shaft. Fixed to the die holder is a die, and the die and die holder define a pelletizing chamber. The shaft supports a roller frame with a plurality of rollers within the pelletizing chamber. The resulting construction is a pelletizer shaft support structure that uses only a single set of bearings. In the preferred embodiment, the main shaft is comprised of an inner shaft and an outer shaft. The inner shaft is located coaxially within the outer shaft and supported within the outer shaft by static bushings. The roller frame and rollers are mounted to the inner shaft. The inner shaft and the outer shaft are both fixed to the frame structure. The outer shaft is fixed in a permanent manner while the inner shaft is fixed to the frame by use of a shear pin to allow rotation under emergency circumstances. During operation of the mill, should binding of the roller mechanism in relation to the die result in undue torque being placed upon the inner shaft, the shear pin will shear and allow the inner shaft and the outer shaft to rotate relative to each other to protect the mechanism from further damage.