Effects of Various Machine Parameters on Cutting Performance for High-speed Cutting of Paddy Crop

Abstract

To achieve optimised cutting performance at higher forward speeds of existing combine harvesters, performance evaluation of available cutting systems was conducted to cut paddy crop (variety: Indrayani). A tractor operated laboratory test set-up consisting of 1-m-wide cutterbar, reel and auger was developed. Freshly uprooted paddy crop was held upright using crop holder assemblies. Knife speed, cutting stroke and forward speed were iterated through set of design of experiments and dependent parameters like cutting force, specific cutting energy and overall cutting efficiency were measured. The results were then analysed and operating parameters were optimised for maximising the forward speed. The cutting performance with optimised parameters was then validated in the laboratory by operating test set-up at optimised settings. It was found that, with increase in the knife speed from 450 to 600 rpm at an interval of 50 rpm, the absolute cutting force was observed to be decreased; however, reverse trend was observed with increase in the cutting stroke from 50.8 to 101.6 mm and forward speed from 2 to 6 km h−1. Statistically stroke length was the most significant factor (α = 0.01) impacting the cutting force and specific cutting energy requirement, followed by forward speed and knife speed. Overall cutting efficiency increased with increase in the knife speed and stroke length; however, a reverse trend was observed with increased forward speed. Highest forward speed of 6 km h−1 was achieved by setting the cutting system at knife speed of 600 rpm and stroke length of 76.2 mm, where peak absolute specific cutting energy, peak absolute cutting force and overall cutting efficiency were 162.9 kJ m−2, 1212.7 N and 86.4%, respectively. Validation experiments show a strong positive correlation coefficient of 0.944, 0.988 and 0.985 for peak absolute cutting force, peak absolute specific cutting energy and overall cutting efficiency respectively. Thus, forward speed of existing combine harvesters could be increased at improved levels of cutting efficiency with the said optimization approach.