Development of a Technique to Reduce Combine Header Losses in Soybeans (Part 3)

Analysis of Forward Motion of Stalks by Examination of Stalk Cutting

Abstract

We set up a model experiment for cutting stalks with a combine to investigate the forward motion of the stalk during the gathering process. The speed of movement of the stalk's center of gravity was provisionally termed the center of gravity speed. When the stalk was assumed to be a rigid body, the calculated center of gravity speed tended to be higher than the value actually measured with a side-mounted video camera. We then assumed that all motion energies were converted into potential energies of the deflection of the stalk, and corrected the center of gravity speed. The calculated center of gravity speed then agreed closely with the measured value. After calculating the center of gravity speed using our design parameters, it was shown that a narrower guard pitch led to a lower center of gravity speed. Next, after examining the relationship between the slip of the stalk on the blade edge and the center of gravity speed during the cutting process, we found that a longer slip of the stalk tended to result in a higher center of gravity speed. The slip tended to shorten as the cutting angle approached 0°, suggesting that a normal blade should be fitted at an advance ratio of 1.03 and a slim blade fitted at an advance ratio of 1.91. It was thus shown to be important in cutter-bar design for the guard pitch to be narrower and that the combination of knife angle and the advance ratio be selected to bring the terminal cutting angle close to 0°.