Design and test of post-seat weeding machine for paddy

Aiming to solve problems in organic rice weeding a type of post-seat weeding machine was designed for rice paddies.The differences in the strengths and lengths of the root systems between the rice seedlings and the weeds were studied,and the motion track of the weeding wheel was analyzed to obtain the structural parameters of the weeding wheel.Then,the structural model of the weeding wheel was designed.The interaction process between the weeding wheel and soil in the paddy fields was simulated and analyzed based on the discrete element method,so as to investigate the working resistance change tendency of the weeding wheel and the orderliness of the soil disturbances.An orthogonal test was designed in this study,with three factors:the hoeing depth,the rotation rate of the weeding wheel,and the forward speed of the device.The influences of different operation parameters of the weeding machine on the weeding torque and soil disturbance speed were obtained based on a variance analysis of the test results.A multi-index comprehensive weighted scoring method was used to evaluate the simulation results.A soil bin test was conducted to verify the simulation results.Field experiments were carried out to test the working performance of the weeding machine.The comprehensive scoring results indicated that a better working performance of the weeding operation could be obtained when the hoeing depth was 50 mm,the rotation rate of the weeding wheel was 240 r/min,and the forward speed was 0.6 m/s.The results of the soil bin test were consistent with the simulation results.The results of the field experiment revealed that the weeding machine met the requirements for organic rice weeding.These results can provide a reference for the design of weeding machines for paddy fields.

Design and experimental validation of sliding knife notch-type disc opener for a no-till combine harvester cum seed drill

One major constraint in developing a combine harvester cum seed drill(CHCSD)is the limited space available for the attachment of no-till furrow openers.Investigating the straw stubble cutting and furrow opening performance of small-sized disc furrow openers is critically important for the development and the optimization of the no-till seeding assemblies.A set of down-scaled sliding knife notch-type disc opener(SKO),modified notch-type disc opener(MNO)and smooth-type disc opener(SDO),with upper size limit of 160 mm,were designed and fabricated for field testing.Experimental results show that for small-sized disc furrow openers of the same type,a larger disc diameter yields a greater furrow depth and width.For small-sized disc furrow openers with an identical diameter,SKOs yield a greater furrow depth and width than MNOs,with SDOs yielding the lowest values.The measured furrow depth and width for an SKO with diameter of 160 mm are 3.52 cm and 3.56 cm,respectively,meeting the no-tillage furrowing requirements for a CHCSD.The highest stubble cover rate of 62.5%is obtained for the SKO with diameter of 160 mm.Therefore,this opener has greater ability to remove stubble from the furrow and seeding band than the other designs.Finally,experimental results of the stubble cutting rates confirm that,for irregularly placed straw and residue,the stubble cutting rate of the SKO with diameter of 160 mm is the highest at 61.7%.