天牛仿生大麻收割机切割刀片设计与试验

针对现有大麻收割机切割刀片存在切割阻力大、功耗高、割茬质量差的问题。运用仿生学原理,通过提取天牛上颚切割齿部位齿廓曲线,以天牛切割齿廓代替普通稻麦收割机刀片的三角形尖齿,设计了仿生切割刀片。利用双动刀切割装置测试平台,对收割期大麻茎秆进行了仿生刀片和普遍刀片单茎秆切割性能对比试验。试验表明,2种刀片的切割力-位移曲线都可分为挤压、切割和切割完毕3个阶段,其中仿生刀片具有切入能力强、切割茬口较平齐、切割质量好的优势。通过对2组切割试验数据进行均值统计和方差分析可知,仿生刀片和普通刀片单茎秆最大切割力和切割功耗平均值分别为442.6、478.1 N和2.16、2.35 J,仿生刀片和普通刀片相比,平均最大切割力和切割功耗分别降低7.4%和8.0%,表明仿生刀片较普通刀片具有更优的减阻降耗性能;方差分析表明刀片类型对单茎秆最大切割力影响极显著(P0.01),对单茎秆切割功耗影响显著(P0.05)。

Design and test of cutting blade of cannabis harvester based on longicorn bionic principle

Abstract: Cutting blade is one of the key parts of a cannabis harvester and the cutting performance of the blade directly determines the performance of the machine. Due to the current lack of special cutting blades for existing cannabis harvesters, rice and wheat harvester cutting blades have to be utilized instead. However, these cutting blades have problems associated with large cutting resistance, high energy consumption, and poor cutting quality. For these reasons, this study aimed to utilize the principle of bionics to develop a longicorn mouthparts palate for a bionic prototype. This was achieved by extracting the cutting tooth profile curve of longicorn mouthparts palate, instead of the ordinary rice and wheat harvester blade triangular tines, and thus designing the bionic cutting blade. Using a double-action blades testing system, which was composed of a self-developed double-action blades cutting device and a WDW-10 computer-controlled electronic universal testing machine, a single stalk cutting performance contrast test was carried out using the cannabis stalks of harvest time. Comparing the 2 types of blades'' cutting force -displacement curves can be seen that both of the curves could be divided into extrusion, cutting, and cutting out stages. In extrusion stage, due to the large pitch and sharp teeth of the bionic blade, the unit area of cannabis stalk suffered great stress, consequently strengthening the cutting ability of the bionic blade. While the teeth of ordinary blades were arranged closer, achieving the same cutting driving force, the unit area of cannabis stalk suffered less stress, thus, the blade showed more effect of compression on the stalk. In cutting stage, due to the unique arc tooth and tooth back groove structure of the bionic blade, the teeth edge mainly played a role of sliding cut, which can greatly reducing the cutting resistance during cutting. Secondly, the adjacent protrusions of the arc tooth boundary formed a wedge block structure, which resulted in the effect of splitting the transverse xylem instantly. In addition, the back groove of tooth played a role of accommodating the shred wooden material, which can also reduce the resistance of cutting. While, due to the close arrangement of the triangular teeth of ordinary blade, the sliding cut effect was poor and they had no capacity to accommodate the shred material. When cutting, the structure suffered from a blocking effect instead, which resulted in an increase of cutting resistance. In cutting out state, due to the bionic blade can cut more thoroughly, less uncut bark fiber and wood debris entered the two opposite blades, thus keeping the friction small, and the bionic blade force is closer to no-load driving force. Comparison of cutting stubbles of two types of blades can be seen that the stubbes cut by bionic blades is more flush than that by ordinary blades. The statistical average of both groups of test data showed that the single stalk maximum cutting force and the cutting energy consumption of bionic blade and ordinary blade were 442.6 N, 478.1 N and 2.16 J, 2.35 J, respectively. In comparison to an ordinary blade, the bionic blade achieved a reduction of the average maximum cutting force and cutting energy consumption by 7.4% and 8.0%, respectively. This showed that the bionic blade has a better performance of drag reduction and consumption reduction than the ordinary blade. The maximum cutting force of different blades was verified via F test, resulting in an F value of 15.49 at a significance level of P<0.01, which reveals that the blade type has a significant influence on the cutting force. Furthermore, the cutting energy consumption of different blades was also verified via F test, resulting in an F value of 5.735 at a significance level of P<0.05, which reveals that the blade type also has a significant influence on the cutting energy consumption of a single stalk.