食葵籽粒双层振动风筛式清选装置设计与试验

    Design and experiment of the cleaning device with double-layer vibrating air-sieve for edible sunflower seeds

    • 摘要: 针对食葵机械化收获清选环节损失率和含杂率均偏高等问题,该研究设计了一种双层振动风筛式食葵清选装置,主要由风机、导料齿板式上筛体、阶梯抖动板式下筛体及驱动机构等组成。根据不同品种食葵籽粒大小,清选装置上下筛分别配套筛孔尺寸为20、18 mm和18、16 mm的两组编织筛网。通过清选过程物料动力学分析,获得影响该装置工作性能的主要因素为气流方向角、曲柄转速及筛面倾角。应用Fluent-EDEM耦合技术仿真模拟食葵清选过程,验证清选装置结构合理性。以大籽粒“三瑞10号”和小籽粒“葵花363”两种食葵为试验对象,气流方向角、曲柄转速及筛面倾角为影响因素,含杂率和损失率为评价指标,在自制清选装置台架上分别开展正交试验,利用综合分析法得出影响清选性能的主次因素依次为曲柄转速、筛面倾角、气流方向角,较优参数组合为气流方向角21°、曲柄转速250 r/min、筛面倾角4°,此时含杂率低于3%,损失率低于2%,满足食葵机械化收获标准,且作业性能优于已有食葵清选装置。该研究可为食葵机械化收获过程中清选系统的改进优化提供技术支撑。

       

      Abstract: The current harvesting of edible sunflowers can be discrete two-stage mode, including manual picking for the insert trays to dry for 7 to 10 days, and then machine picking, threshing and cleaning. Edible sunflower combine harvesting equipment is still lacking in adaptability, low cleaning loss, and impurity rate in the field, due to that mostly modified from wheat, and corn harvesters. Cleaning is one of the key steps in the mechanized harvesting of edible sunflower, which is directly related to the rate of impurity and loss of sunflower seeds. Sunflower cleaning device has been focused mainly on theoretical analysis and parameter optimization in recent years. However, only a single-hole sieve has been used to explore the seeds passing-through performance of various edible sunflowers, leading to a high impurity rate and large cleaning loss. It is a high demand for the low-loss and high-efficiency edible sunflower cleaning device, in order to promote the high mechanization level of edible sunflower harvesting. In this study, a new cleaning device was designed with the double-layer vibrating air-sieve for the edible sunflower, particularly for the low loss rate and impurity rate during mechanized harvesting. The device consisted of the fan, upper sieve body with guide tooth plate, lower sieve body of step shaking plate, and the drive mechanism of offset crank slider. The structural parameters of the edible sunflower cleaning device were then determined, where the sieve length was 1600 mm, the width was 900 mm, and the clearance of the upper and lower sieve was 120 mm. Mechanical design was also carried out to obtain the crank length of 32.5 mm, the slider stroke of 70 mm, and the slideway inclination of 23°. Two groups were determined by the upper and lower woven sieves with square hole diameters of 20, 18 mm, and 18, 16 mm, respectively. Two varieties of edible sunflower were selected as the ‘Sanrui No.10’ and ‘Sunflower 363’ with the threshing mixture of different seed sizes. The movement process of material on the sieve surface was analyzed to obtain the optimal working conditions and the influencing factors on the cleaning performance. The kinematics of the sunflower on the sieve was also explored to obtain the properties of seeds passing through the sieve using the Fluent-EDEM platform. The simulation results showed that the cleaning device with a vibrating air was successfully realized the cleaning work of sunflower seeds, indicating a reasonable structural design. Orthogonal tests were carried out on the self-developed shelf of the cleaning device, where the influence factors were the crank speed, airflow direction angle, and sieve inclination, whereas, the test indexes were the impurity rate and loss rate. The primary and secondary influencing factors were ranked in descending order of the crank speed, sieve inclination, and airflow direction angle. The optimal combination of parameters was the crank speed of 250 r/min, sieve inclination of 4°, and airflow direction angle of 21°. The optimization of parameter combination was repeated five times on the bench for validation tests. The results showed that the impurity rate of both varieties of edible sunflower was less than 3%, and the loss rate was less than 2%, fully meeting the standard for the mechanized harvesting of edible sunflower. The performance of the cleaning device was also better than before. This finding can provide theoretical support for the improvement and optimization of the cleaning system during mechanized harvesting of edible sunflowers.

       

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