虎杖根系脱土滑梳式辊指的设计与试验

Design and experiment of slide-combing roller finger for Polygonum cuspidatum root-soil separation

根系脱土是中药虎杖收获的重要环节,采用直线梳刷式脱土辊指实现根土分离极为有效,然而直辊与根系作用时,常出现相互勾连、扯拉等不良状况,致使脱土功耗显著增加,为此该文融入滑切方式,设计了一种曲线滑梳式脱土辊指。根据滑切理论,确定了辊指滑梳的临界条件,利用对数螺线方程建立了辊指梳刃的曲线方程,通过辊指的动力学分析,建立了辊指作业的功耗模型,确定了辊指转速、辊指作业长度、辊指滑切角为功耗的主要影响因素,并根据摩擦角与滑切角关系,利用Matlab软件得到摩擦角和滑切角与功耗的伪彩色能量图,确定功耗最小所对应的辊指滑切角为67°。进行功耗及脱净率试验,利用多目标优化设计方法对试验结果进行综合评价。结果表明:在辊指转速为350 r/min、辊指作业长度为30 mm、辊指滑切角为67°时,脱土辊指的作业性能较优,此时脱净率为93.03%,功耗为76.73 W。研究结果可为虎杖根土分离部件的结构改进设计和作业参数优化提供依据。

Root-soil separation is a critical link in Polygonum cuspidatum harvesting.It has been shown that combing machines are very useful for separating soil from root.However,it is a common occurrence during this process for Polygonum cuspidatum to be entangled by the machine,which leads to excessive energy consumption.In order to overcome the imperfections and defects of this kind of machine,a new roller finger for root-soil separation was designed.By applying the slide-cutting theory,the critical slide-cutting angle of the roller finger was calculated.Considering the friction coefficient between between Polygonum cuspidatum and roller finger,the slide-cutting angle was found to be more than 30°.By solving the differential equation and the logarithmic spiral equation,the curve equation of the roller finger was established in polar coordinates.With a mechanical model between Polygonum cuspidatum and roller finger set up,a function involving energy consumption,rotational speed of roller,length of roller finger and slide-cutting angle of the roller finger was obtained.It was found that the optimal slide-cutting angle varied in energy consumption with the difference of the coefficient of friction between Polygonum cuspidatum and roller finger.A pseudo-color energy figure about the relationship among consumption,angle of friction and angle of slide-cutting was shown with the MATLAB（Matrix Laboratory）software by the function derivation of the slide-cutting angle.It turned out that the optimal slide-cutting angle increased slowly as the coefficient of friction grew.Utilizing the curve,the maximal slide-cutting angle was obtained.The rotational speed of roller（Factor A）,the slide-cutting angle（Factor B）and the length of roller finger（factor C）were selected as 3 factors of the orthogonal simulation experiment in order to explore their impact on the rate of soil-detachment and energy consumption.The priority order of the factors for the rate of soil-detachment was A〉C〉B〉A×B〉A×C〉B×C,and that for the energy consumption was C〉A〉B〉A×B〉A×C〉B×C.The rotational speed of roller and the length of roller finger had an extremely profound effect on the rate of soil-detachment while the slide-cutting angle had a profound effect on it.Meanwhile,those 3 factors also had an extremely profound effect on the energy consumption.Although the 3 factors performed differently on the rate of soil-detachment and energy consumption,by utilizing a fuzzy comprehensive evaluation method,a comprehensive evaluation on the results of the rate of soil-detachment and energy consumption was carried out by the multi-objective optimization design method.Results reflected the important differences between the rate of soil-detachment and energy consumption,and a weight matrix was set for fuzzy calculation.According to the comprehensive evaluation,the sequence of the influence of the factors on the comprehensive result was A〉C〉B×C〉A×C〉A×B〉B,and the rotational speed of roller had an extremely profound effect on the comprehensive result while both the length of roller finger and the slide-cutting angle×length of roller finger had a profound effect on it.The results of fuzzy calculation showed that the optimal parameters were as follows：the rotational speed of roller of 350 r/min,the slide-cutting angle of 67°,and the length of roller finger of 30 mm,and under these conditions the rate of soil-detachment was 93.03%and the energy consumption was 76.73 W.