Theoretical analysis of interaction of disc coulters and straw residues under no-tillage conditions

The article presents the theoretical aspects of disc coulters working process under no-tillage conditions. Under no-tillage conditions, effective operation of disc coulters is impeded by plant residues. In the interaction of a disc coulter, plant residues and soil surface, the disc coulter may cut the plant residues, roll over them or press them into the furrow being formed in the soil. The objective of the research is to theoretically study the process of straw cutting by disc coulters under no-tillage conditions and to substantiate the main parameters acting upon the cutting force. Theoretical studies established the dependency according to each the extent of the straw cutting force depends on the disc coulter blade sharpening angle, blade thickness and disc coulter blade length, straw normai stresses, friction coefficient, elastic modulus, straw diameter, its compression path, and other parameters. On the basis of calculations, it was found that if the disc coulter blade sharpening angle is increased by one degree, the cutting force sufficient to cut wheat straw can be reduced by 6.5 N, and reducing the disc coulter blade thickness by one millimetre would allow reducing the cutting force by 12.5 NVytauto Didžiojo universitetasŽemės ūkio akademij