| As an important Chinese medical herb for activating blood circulation,dissipating blood stasis,stimulating menstrual flow,relieving cough and so on,Polygonum cuspidatum whose annual production is more than 6000 t,grows in vast areas in South of Changjiang river in China.It's found that herb extractive has an effect of treatment for angiocarpy disease,cancers,virus and immunity adjustment while modern science technology developing.Increasing rapidly demand for Polygonum cuspidatum has already exceeded supply,resulting from a new pharmacology research into resveratrol extracted from them for medical treatment of AIDS.Although enlarging grown area is the key to make both balance,existing root-soil separation device cannot satisfy request of Polygonum cuspidatum production because of their complicated shapes and composition.So they are still separated from soil manually with low efficiency,high percentage of damage and high labour intensity,which impede development of production of scale.Hence,it's vital to mechanize root-soil separation in order to industrialize their production.Meanwhile,with the representatives of root structures,its sort and the type of root-soil interaction of Polygonum cuspidatum,the mechanical solution on its root-soil desperation offer basis for that of other root crops.Based on analysis of theory about root-soil separation principle and device of rhizome crops at home and abroad,a new device with two rollers was designed according to the physiologic structure of Polygonum cuspidatum and root-soil composites.The work theory of pivotal component of root-soil separation was discussed with research of physical feature of Polygonum cuspidatum and compound body of it and soil and with theory of root-soil compound body borrowed.The compound body broken mechanism and its movement feature were analyzed with numerical simulation in the case of input forces.With experiment research on the device,its working parameters were optimized while its working performance was tested and verified.The main content and its conclusions of research includes:(1)With test research about Polygonum cuspidatum and its compound body with soil,mechanical properties of them was obtained,which would provide a foundation in physical data for design of component of root-soil separation.The test on Polygonum cuspidatum in tension indicated that the diameter of Polygonum cuspidatum have an extreme profound effect on maximum pull tension that it could sustain,its tensile strength and elastic modulus and meanwhile there is a polynomial relationship between the diameter of Polygonum cuspidatum and maximum pull tension.The test on Polygonum cuspidatum in compression indicated that there are obvious crushing critical point and compacting critical point of Polygonum cuspidatum and hence,typical soil broken discipline was found out.Based on the test on it in concussion,the relationship between concussion times and rate of soil-detachment was found out,which indicated that simple mode of root-soil separation is unadaptable for Polygonum cuspidatum.(2)With material analysis on Polygonum cuspidatum theoretically,the basic method to break its root-soil compound body was put forward.It was concluded that improvement of shear strength about soil by rhizome results from its tensile stress being converted from shear stress of soil through friction on contact surface between soil and root.It was put forward that an adequate measure of benefit of root-soil separation is the crackle of its soil with combination between theory and practice.(3)Working features of various rollers of root-soil separation with rotating,sliding-combing and combing combination,were obtained at the first time through dynamic analysis on pivotal component of root-soil separation with test bench which consists of two rollers of root-soil separation.A power consumption model of different root-soil separation mode was established in order to define types of roller with analysis of working mode of different rollers;a conveying speed model of products of Polygonum cuspidatum was established in order to determine the position of reversal roller through analysis on inneraction between roller finger and it;a curve function of roller finger was established in order to critical condition of sliding-combing work through slide-cutting principle;a power consumption model of rollers with different curves was established in order to determine the best scale of slide-cutting angle.As a result,a logarithmic spiral curve of roller finger was determined which kept the slide-cutting angle static during work of root-soil desperation that caused stability improvement and relented inflation.Meanwhile,its curve structure,with the mode of action of from-point-to-line when combing,could reduce resisting force and improve the behavior of root-soil desperation.(4)In use of discrete element method simulation with computer technology,energy absorption and inner-movement strength of various zones were analyzed,which,as a new dynamic analysis method of root-soil compound body kinematic behavior,provide evidence about machine component of root-soil desperation.It was indicated that energy absorption in root of direct action zones don't correlate to inner-movement strength of broken about particles of soil positively,that there is a positive relationship between energy absorption in middle direct action zones and inner-movement,and that energy absorption in indirect action zones haven't no correlation to inner-movement.Based on analysis on inner-movement of particles of soil,inner-movement in the particles of soil ahead of the roller resulted from inneraction of impact and resistance among different magnitude speed particles in the surface of speed gradient which comes into being through medium transport from soil to particles,while inner-movement in the particles of soil behind of the roller resulted from their collapse.In comparison of ahead and behind the roller finger working area,inner-movement in the particles of soil behind roller was weak and happened later than the ahead ones.Inner-movement strength in the middle zones is highest while outer-movement strength in the top of the roller is highest.And outer-movement strength in the outer zones happened later than the inner ones.Outer-movement maximum strength with a feature of micro mobility happened in time sequence with analysis on the track of particles of outer-movement.Meanwhile,the analysis on tangent-movement particles showed that their happening numbers changing tendency among different zones almost the same with their inter-kinetic energy and compression potential energy changing from an increasing period,a waving period to a period of the latter transformation to the previous.(5)Evaluating indicator about Polygonum cuspidatum reversal was determined,which are throwing height and the quotient ? of angular kinetic energy and total energy.Otherwise,the best working parameters was found through optimization analysis.It was indicated that speed of reversal roller has a stable influence on throwing height while the longer roller finger has an unstable influence on throwing height according to the analysis of the relationship among its length L,speed N and the indicator by ADAMS.The indicator was almost determined by the length of roller while the speed of it has a slight influence on the indicator.Due to this analysis,an ideal roller should be at low speed with shorter finger.A regressive numeric model was established for the indicator through response surface optimization experiments.It indicated that the device had the highest level of indicator(h=36.2mm,?=0.75)with length of 48 mm and speed of 50 r/min.(6)The best parameters of two roller fingers——linear and curved were separatelyobtained in the case of highest soil-detachment and lowest energy consumption with the systemic research on experiments of the machine.With of soil-detachment behavior,the rate of it increased along with the increasing of the speed of roller of root-soil separation and the rate of it increased slightly along with the speed of reversal roller.Otherwise,the rate of it increased and then decreased along with the increasing of the length of the roller finger: rapid growth at 20~80 mm,slightly decline between the length of 80~140 mm and rapidly falling when it exceeded 140 mm.The experiment was also indicated that the device had the best performance of soil-detachment behavior with 40 mm of the working length of roller of root-soil separation and 80 mm of the working length of reversal roller.In the test of rollers with finger of straight line,the best parameters are as follows: 500r/min of speed of the roller of root-soil separation,240r/min of speed of reversal roller and 230 mm of the horizon distance between them,with the performance of 91.2 % of the rate of soil-detachment and 1.35t/h of productivity.In the test of rollers with finger of curve line,the best parameters are as follows: 350r/min of speed of the roller,67° of slide-cutting angle of roller and 30 mm of the working length of roller finger,with the performance of 93.03 % of the rate of soil-detachment and 76.73 W of energy consumption.And meanwhile,the priority of parameters in the fuzzy calculation of the comprehensive evaluation was roller speed > roller working length > slide-cutting angle.With comparison of experiments of two roller fingers,it indicated that linear ones had higher productivity,soil-detachment and energy consumption than the curved ones. |
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