Search

The header frame of full-feeding rice combine harvester was characterized by severe vibration due to the excitation force generated by the movement of each working part. In order to solve the problem, the parametric model of the header frame was established, and the accuracy of the finite element model was verified by comparison of the results of the free modal analysis and free vibration modal test based on Eigensystem Realization Algorithm (ERA). Then the constrained modal frequencies were calculated and compared with the external excitation source frequencies, the results showed that the first and eighth order modal natural frequencies were coupled with the excitation frequencies of the threshing cylinder and the engine respectively, which were apt to resonate. To avoid resonance and achieve lightweight design, topology optimization, and finite element analysis were carried out. The optimization results showed that the strength and rigidity meet the requirements and the weight was 14.17% lower than before. The first and eighth order modal natural frequencies were far away from the excitation frequencies range of the threshing cylinder and engine, and the frequencies were far away from the range of each excitation frequency, which effectively avoided the occurrence of resonance. Field experiments showed that the peak value of the vibration acceleration in the three directions of the 8 measuring points of the optimized header frame was significantly reduced, which effectively reduced the vibration of the header frame during harvest. This study provides a method for obtaining the vibration characteristics of key components of agricultural machinery and provides a reference for the weight and vibration reduction of header frames of rice, wheat, rape, and other crop combine harvesters. [ABSTRACT FROM AUTHOR]

In order to examine the relationship between the seeding rate of a hill-direct-seeding machine and seedling rate in field, six rice varieties typical for cold areas were selected to conduct the indoor germination tests and field seedling experiment using a hill-direct-seeding machine. Indoor germination and field seedling tests were performed to study the correlation among the mechanical precision seeding process, machine seeding rate and field seedling rate. The results showed that the indoor germination rates were higher than 90%. The series of spoons was adaptable to the hill-direct-seeding process. The number of seeds was 28-30, 18-20 and 8-10 grains/hill. The field seedling rates were higher than 85%. The rice variety of Suijing-18 achieved the best field seedling rate, and the highest seeding rate was 18-20 grains/hill, while the average field seedling rate was 94.25%. On this basis, the action law of the hill-direct-seeding machine and the main factors influencing the field seedling rate were analyzed. Mechanical vibration resulted in a higher average seeding rate of the middle seed metering device of the hill-direct-seeding machine than that of both ends. The force between the seed spoons and rice seeds mechanically damaged the seed buds, resulting in the actual field seedling rate being lower than the ideal indoor germination rate. The experimental results can provide a reference for the selection of typical direct seeding rice varieties, the improvement of key components of hill-direct-seeding machines, and the promotion of agronomic models. [ABSTRACT FROM AUTHOR]

Since there are some problems in the previous cam of deep-fertilization liquid fertilizer applicator, such as poor precision and low-fertilization performance, a method of the contour line of a cam was proposed based on Matlab GUI development platform. Bernoulli' equation between the liquid fertilizer and the pressure valve of the fertilizer-spraying needle was founded. Moreover, the motion angles of a rise travel and return travel were corrected and the corresponding parameters of the contour line of the cam were obtained. Equations of cam moving from rise travel to return travel were derived according to the simple harmonic motion. In addition, 3D model of cam was established by applying the Pro/E software and the rationality of the cam design was verified. The static analysis of the cam was carried out under working conditions and the corresponding dynamics analysis was performed based on D'Alembert's principle. And then relationships between the binding force and the drag torque were obtained. A bench test indicates that when the pressure of a hydraulic pump is 0.5 MPa and the velocity of a output shaft is 50 r/min, the average consumption of the fertilizer is 19.7 mL for each measurement, which meets the corresponding agronomic requirement, i.e. 20 mL. When the rotation angle of the cam is 8.6° and the rise displacement of a plunger is 0.84 mm, the mouth of the fertilizer-spraying needle sprayed liquid fertilizer as soon as it got into the soil and stopped spraying as soon as it got out of the soil. The results show that the designed contour line of the cam meets the requirement, that is, the mouth of the fertilizer-spraying needle should spray liquid fertilizer as soon as it gets into the soil and stop spraying as soon as it gets out of the soil, which meets the agronomic requirements, that is, fertilizer should be sprayed deeply and precisely. And this study lays a theoretical foundation for designing the cam of intermittent type distributor and provides relevant parameters. [ABSTRACT FROM AUTHOR]

A spray and rotary tillage combined disinfection machine for soil was designed to solve the serious problems of plant diseases and insect pests, and it was divided into two operations which were soil disinfection and rotary tillage. The main structure and working principle of this machine were illustrated and analyzed. The reasonable structural parameters of key parts were carried out, such as spraying disinfection system and rotary tillage land preparation system. To optimize the working performance and obtain better operation parameters, the orthogonal experiments were carried out to analyze influences of three factors (forward speed of driving machine, rotational speed of rotary tillage, and working pressure) on the working performance. The mixing uniformity coefficient and the variation coefficient of spraying were chosen for evaluating working performance. The range analysis and variance analysis were studied based on experimental data. The results showed that, the mixing uniformity coefficient of spraying was 93.95% and the variation coefficient was 6.01% with a working speed of 3 km/h, rotational speed of 2000 r/min and working pressure of 2.0 MPa. The machine can meet the agronomic requirements of disinfection and plowing, which was designed simply, compactly and strong applicability. The results can provide a guidance and technical support for preventing the plant diseases and insect pests, developing sustainable and ecological agriculture and improving the efficiency of compound cultivation. [ABSTRACT FROM AUTHOR]