Design and Experiment of Low Trash Snapping Knife Rolls for Corn

Abstract:

Snapping mechanism with four knife rolls and stripper plates has the advantages of smaller kernel damage, faster capacities and higher ground speeds compared with spialribbed snapping rolls, but knife rolls are more aggressive, which can lead to more stalk breakage and more trash in the load. In order to solve this problem, a new type of fluted rolls was designed through the analysis of causes of stalk breakage. Four additional rolls of L shape were installed between each knife roll, which provided a straight pulldown of stalks. Theoretical analysis and computer simulation were made to determine structure parameters, and then an experimental prototype was made to test its performance. The experiment was carried out in existed snapping apparatus test bench, and three snapping mechanisms were chosen to do this comparison, which were traditional four blades snapping rolls and fixed snapping plate, four blade pull stalk rolls and clearance adjustable snapping plate and the new snapping rolls and clearance adjustable snapping plate. The ratio of trash in load was measured. Experiments results were analyzed by carrying out variance and significance analysis of effects assessed. Different snapping mechanisms had no significant effects on ratio of trash in load with confidence of 0.95，but different snapping knife rolls had significant effects on ratio of trash in load. The ratio of trash in load was reduced from 3.3% to 1.45% with combination of clearance adjustable snapping plate and new snapping knife rolls compared with traditional four blade snapping rolls and fixed snapping plate, wherein the contribution ratio of adjustable snapping plate and new blade rolls were 67.0% and 33.0%, respectively. The ratio of trash in load was the least with new snapping knife rolls and clearance adjustable snapping plate, which was 1.45%, and it met the requirement of national standard regulations and achieved the design purpose.