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The complex mechanical system of a rice combine harvester not only has various excitation sources, but also, the vibration transmission path between each working device and the vibration contribution characteristics to the frame are not clear, so it is difficult to perform a reduction vibration design for the sharp vibration of the rice combine harvester frame. Therefore, based on the comparison and improvement of multiple classical transfer path analysis methods, this paper analyzed the vibration transfer characteristics and transfer characteristics of each harvester by the discrete time matrix method and operating path method. In the Experimental section, through the vibration characteristic experiment firstly, this paper obtained the power spectrum variation and the most needed optimized path in the transmission path of each device under each operating condition. Secondly, through frame simulation analysis under the exciting force, we obtained the vibration damping areas that needs to be optimized. Finally, the damping optimization experiment connected with the vibration characteristic experiment, and the excitation force simulation analysis was performed. The results of the damping optimization experiment displayed that the maximum change value of the vibration acceleration of the cutting table decreased from 7.862 m·s−2 to 3.522 m·s−2, decreasing by 55.2%, and the peak amplitude of the multipoint test in the cab was 5.4, 5.3, 1.7 and 2.0 μm, respectively, which was significantly reduced, so the optimization effect was significant. This study provides theoretical support for the vibration reduction optimization of a rice combine harvester frame.

The screen surface particle distribution is an important factor affecting screening performance. A vibrating screen with an adjustable horizontal attitude angle was used, the non-uniform feeding and horizontal attitude angles were used as variables and the screening of rice particles was simulated by the discrete element method. The screen surface distribution and movement speed of the rice particles were analyzed based on the influence of the variables on screening performance. The results indicated that the material distribution became more unbalanced with the increase in non-uniform feeding, and the particles’ speed increased with the increase in attitude angle on the y-axis. The particles experienced accelerated dispersion, which improved the unbalanced distribution of the particles and screening performance. According to the loss rate, the horizontal attitude angle adjustment model was established and optimized under non-uniform feeding. The reliability of the model was verified by simulation. A bench test was carried out to verify the simulation. The optimization model can reduce the loss rate, improve the screening performance of non-uniform feeding, and provide a reference for the material screening of non-uniform feeding.

The briquetting technology of rice straw could increase the bulk density of the straw, reduce transportation and storage costs, and improve resource utilization. This paper analyzed the working principle of the air-conveying integrated device in briquetting machines. High-speed photography technology was used to track and record the movement process of crushed straw material in the air-conveying cylinder area. It was compared with the simulation results of the average velocity of crushed straw material to verify the reliability of the simulation. The results showed that the flow of straw scraps in the straw-shredding and air-conveying integrated device was relatively stable when the impeller speed was 630 r/min, the number of blades was three, the blades were tilted back 15°, and the radius of curvature of the air-conveying tube elbow was 700 mm. At the same time, the speed distribution was uniform, and the highest throwing speed reached 4.5 m/s to 4.8 m/s. After optimization, the average increase rate of briquette density was 2.61% and the average increase rate of briquette productivity was 2.52%. The fluid movement law of the straw-shredding and air-conveying integrated device studied in this paper could be used to optimize the air-conveying device, improve the efficiency of straw briquetting and the utilization rate of straw resources.

The solidification and molding of straw has been an effective method for comprehensive utilization of straw resources. However, the existing die-roll extrusion-type straw briquetting machine has challenges, such as the easy blockage of ring die holes and the unstable quality of the briquette. In this paper, the influence of four factors, including moisture content of straw, molding temperature, clearance between die and roller, and spindle speed on the quality of the briquette were studied. The regression model of the relaxed density and impact resistance of the briquette were established to obtain the optimal values of these factors to provide the best parameters for producing straw briquette. The results indicate that under the experimental conditions of moisture content 22.335%, temperature 85.127 °C, clearance between die and roller 3.099 mm, and spindle speed 172.712 r/min, the maximum relaxed density and impact resistance of the briquette were 1.144 g/cm3 and 74.76%, respectively. The performance of the briquette already meets the requirements for combustion, transportation, and storage.