气吸式马铃薯排种器正压吹种零速投种性能优化试验

为提高马铃薯排种精度,弥补现有零速投种技术存在的不适合高速作业、投种点高等缺点,提出利用正压气流为下落的种薯沿播种机前进方向反向加速以实现零速投种。对投种过程进行基础解析,获悉影响零速投种性能的主要因素及各因素的试验取值范围。以吹种正压、投种角和排种器转速为试验因素,合格指数、重播指数、漏播指数及变异系数为评价指标,进行二次正交旋转回归试验,建立各指标与因素间的回归数学模型,分析各因素对评价指标的影响规律,可知当排种器转速为25~31 r/min时,影响排种性能的主要因素是排种器转速,当排种器转速31~40 r/min时,随着吹种正压的升高,合格指数上升、变异系数下降,此时零速投种对提升排种质量效果明显。根据回归模型进行参数优化,当吹种正压15 k Pa、投种角57°、排种器转速35 r/min时,排种合格指数、重播指数、漏播指数、变异系数分别为95.22%、3.51%、1.27%和9.43%,满足马铃薯排种作业要求。该研究为优化气吸式马铃薯排种器、提升马铃薯等大粒种子作物及其他作物排种精度提供技术支持。

Performance optimization test on air-suction potato seed metering device with positive pressure airflow and zero-speed seeding

Abstract: The existing zero-speed seeding technology has many disadvantages, such as being not suitable for high speed operation and the seed charge position too high. To make up for these shortcomings, a new technique of zero-speed seeding was proposed. This technology can also improve the precision of potato sowing. The positive pressure air was used as the driving force making the dropping tuber accelerated along the opposite direction of the seeding machine. In the process of falling, the horizontal velocity of tuber was zero relative to the ground. The zero-speed seeding technique was applied to sowing potato with this method. On the basis of the analysis of the throwing process, the main factors that affected the performance of zero-speed seeding were obtained, and the range of the test values of each factor was determined. These main factors were positive pressure, throw angle and rotation speed of the device. With these parameters as the experimental factors, a dual quadratic orthogonal rotational regressive test was designed. The qualified index, multiple index, missing index and coefficient of variation were selected as evaluation indices according to the national standards. The regression mathematical models between the indices and the factors were established after the test. The impacts of the factors on the evaluation indices were analyzed by using these mathematical models. The effects of positive pressure and rotation speed on the 4 indices were significant or highly significant. The throw angle had only a slightly significant effect on the coefficient of variation. When the seed metering device''s rotation speed was 25-31 r/min, the main factor affecting the performance of seeding was the rotation speed. Each index value changed slightly with the change of positive pressure. When the seed metering device''s rotation speed was 31-40 r/min, zero-speed seeding function of the positive pressure could effectively improve the quality of seeding. The qualified index increased and the coefficient of variation decreased with the increase of the positive pressure. At the same time, these 2 indices, the multiple index and the missing index, both had different degrees of decline. Parameters were optimized based on regression models. With the maximum qualified index, the minimum variation coefficient, the minimum multiple index and the minimum missing index as the optimization objectives, the ranges of the factors were as follows: the positive pressure of 5-15 kPa, the throw angle of 45°-75° and the rotation speed of 25-40 r/min. And taking into account the agronomic requirements of potato cultivation, the missing index was expected to be not greater than 3%. Optimization results showed that, the qualified index was 95.22%, the multiple index was 3.51%, the missing index was 1.27% and the variation coefficient was 9.43% under the condition of the positive pressure of 15 kPa, the throw angle of 57° and the rotation speed of 35 r/min. The seeding performances of developed device met the requirement of precision seeding. Results in the research give the guidance for the optimization of air-suction potato seed metering device, and provide a technical support for improving the seeding accuracy of potato and many other crops.