缓冲筛式薯杂分离马铃薯收获机研制

针对现有马铃薯收获机薯土分离效果不理想、伤薯率和破皮率较高等问题,该文采用"2级高频低幅振动分离+薯秧分离及侧输出+低位铺放"的薯土分离工艺,研制了一种缓冲筛式薯杂分离马铃薯收获机,该机具主要由挖掘装置、松土限深装置、切土切蔓装置、分离筛、振动调整装置、薯秧分离装置、秧蔓侧输出装置、低位铺放装置以及压实整平装置等部分组成。结合分离筛末端与缓冲筛衔接处的薯杂分离状况,分析了缓冲筛倾角变化对薯块和秧蔓的影响规律,优选出较佳的缓冲筛倾角为36°。试验结果表明,在收获速度为0.88和1.16 m/s时,生产率分别为0.41和0.54 hm~2/h,伤薯率分别为1.47%和1.12%,破皮率分别为1.89%和1.07%,各项性能指标均满足相关标准的规定。随着收获速度的增加,薯块碰撞加速度峰值和碰撞次数均减小,可有效降低伤薯率和破皮率,但明薯率有所降低;反之,碰撞加速度峰值明显增大,明薯率提高的同时伤薯率和破皮率也明显增大。薯块位于分离筛上对应于薯垄边缘位置时,容易产生较大的碰撞加速度峰值(150g)。研究结果可为进一步探讨薯土分离减损控制方法及薯土分离工艺的优化改进提供参考。

Development of potato harvester with buffer type potato-impurity separation sieve

Abstract: Harvesting is the most crucial step of the whole potato production mechanization process, and the most challenging issue is to separate potato, soil and impurity thoroughly and meanwhile control the damage rate and bruising rate of potato. It is widely recognized that there exists some unsatisfactory separation effect problems like higher bruising rate and damage rate and lower exposed rate during the process of mechanical potato harvest. To solve these problems, based on the technology of potato-impurity separation with 2 segment of high frequency and low amplitude vibration separation, potato seedling separation and side conveying and low position laying, a new potato harvester was improved through setting low position laying segment and potato-impurity separation device with buffer sieve. The potato harvester was consisted of digging parts, soil loosening and depth control wheel, cutting device of soil and seedling, separation sieve, vibration adjustment device, device of potato and seedling separation, device of side conveying of seedling, low position laying device and compaction leveling device. In that way, it can reduce the drop height effectively and benefit for potato-impurity separating and potato-seeding separating during the process of mechanical potato harvest. As such, the field harvesting experiments were carried out, when the harvesting speed was 0.88 m/s, the effects of the inclination angle of buffer sieve on the kinematic characteristics of potato and seedling were analyzed when the inclination angle of buffer sieve was 27°, 36° and 45°, and the better inclination angle of buffer sieve 36° was selected. At the meantime, the results showed that peak impact acceleration produced by potatoes on the buffer sieve was relatively small, and the peak impact acceleration mainly came from the impact contact between potatoes and the separation sieve. Therefore, it is demonstrated that the low position laying device had a good performance to reduce drop impact, and to reduce the damage rate and bruising rate. The field harvesting experiments results showed that, the productivity was 0.41 and 0.54 hm2/h, the damage rate was 1.47% and 1.12%, and the bruising rate was 1.89% and 1.07%, respectively when the harvest speed was 0.88 and 1.16 m/s, the field harvesting experiment results and evaluation indeices met the requirements of relevant standards. The results also indicated the peak impact acceleration and impact number of potatoes were decreased with the increase of harvesting speed, which could effectively reduce the damage rate and bruising rate. However, the exposed rate decreased with the increase of harvesting speed, the main reason was the mixture of potato-impurity influxing into the separation sieve in unit time increased correspondingly, and soil worked as buffer in the process of potato-impurity separation with the increase of harvesting speed. On the contrary, the peak impact acceleration and impact time of potatoes were increased significantlyCompared with the potatoes located in the middle of the ridge on the separation sieve, it was easy to produce the larger peak impact acceleration when potatoes located on the separation sieve corresponding to the edge position of potato ridge, it was mainly due to the relatively weak soil buffering and protection for potatoes at this location, so the probability of direct contact between potatoes and rods was greater. This research may provide a technical reference for further study on the loss reduction control method of potato-impurity separation and the optimization and improvement of potato-impurity separation process.