Test of a Device to the Combine Harvesters for Cutting into Very Small Pieces and Spreading of the Straw

1 Institute of Land Reclamation and Mechanization, BG - 1331 Sofia, Bulgaria
2 "Nikola Poushkarov" Institute of Soil Science, BG - 1080 Sofia, Bulgaria


IVANOV, D., T. MITOVA, G. KOSTADINOV and I. DIMITROV, 2006. Test of a device to the combine harvesters for cutting into very small pieces and spreading of the straw. Bulg. J. Agric. Sci., 12: 123-132

An appliance with hinge installed knives for cutting into small pieces and spreading of the straw on the field, simultaneously with grain gathering, has been created and tested. The study has been carried out through a set of controlled one-factor experiments. The main purposive functions of the study are as follows: necessary operation power for the appliance (KW); specific power consumption (KWh/t) and average length of cut (mm); The cases of controlled factors of the experiments are: re-covering of knives and contra-knives: L = 20, 50 and 80 mm; loading of the appliance with straw mass: Q = 5,8 and 11 t/h; peripheral speed of the rotor (cutting speed): V= 13,16 and 19 m/s; distance (clearances) between knives and contra-knives: B = 12,18 and 24 mm; The constant factors are: hinge installed knives; working wide - 1200 m; diameter of the auger - 500 mm; thickness of the knives and contra-knives - 200 mm; position angle between knives and contra-knives -15 grad.; wedge angle of knives and contra-knives - 30 grad.; location of leading blades - middle.
The variation charts of necessary operation power for the appliance, specific power consumption and average length of cut to variation of the controlled factors, have been determined. The respective adequate equations of regression, describing the processes of cutting the straw into small pieces at the same time with grain gathering, have been settled.

Key words: combine harvester, device, spreading, straw, cutting