Design And Experimental Study Of Stem Cutter For Wild Chrysanthemum

Wild chrysanthemum is a kind of common Chinese herbal medicine,which has the function of evacuating wind and heat,reducing swelling and detoxifying.In clinical practice,wild chrysanthemum components are commonly used to treat chronic pelvic inflammatory disease,mumps,influenza,etc.For the problems of high cutting resistance and high power consumption in cutting the stems of wild chrysanthemum,a kind of cutter was designed based on the investigation of the growth and mechanical properties of wild chrysanthemum plants,combined with bionics.The cutter was analyzed and optimized by finite element simulation,and bench test was carried out to verify the feasibility of simulation data of bionic cutter for chrysanthemum stem,verify the cutting performance of bionic cutter,and lay the cutting foundation for the mechanization of wild chrysanthemum harvest.The main research contents are as follows:(1)Determination of physical characteristics and finite element parameter calibration of Chrysanthemum stem.The plant growth and mechanical characteristics of chrysanthemum were measured.Plant growth characteristics included plant spacing,row spacing,plant height,diameter range,water content,etc.,which were obtained by means of investigation and sampling calculation.The mechanical parameters,including bending strength and shear strength,were measured on a biomechanical test machine.Through the investigation and measurement of the physical characteristics of the chrysanthemum stem,it can provide the basis for the modeling of the chrysanthemum stem and the kinematics and dynamics analysis of the cutting operation.Aiming at the lack of accurate model in finite element simulation of mechanized harvesting of wild chrysanthemum,taking the stem of wild chrysanthemum in harvest period as the research object,the finite element simulation model of cutting the stem of wild chrysanthemum was established,and the key parameters were calibrated by comparing the simulation experiment with the actual experiment.The results showed that under different diameters,the error between the simulated value and the measured value of the maximum shear force was less than 7.8%.(2)The overall scheme of wild chrysanthemum stem cutter was confirmed.Firstly,combined with the characteristics of wild chrysanthemum stem,the overall design requirements were clarified.Secondly,the overall scheme of the cutter was determined,including the selection of the cutter type,the analysis of the structure and working principle of the selected cutter,and the dynamic analysis of the cutting process.Finally,the type of driving device was determined and the key parameters were determined.(3)Cutter blade optimization design.Three kinds of bionic blades were designed based on the profile of the cricket’s upper jaw cutter blade.On the basis of the previous parameters calibration of the stems of chrysanthemum,the dynamic simulation analysis of stem cutting with ordinary blades and three bionic blades was carried out,and the best cutting cutter with the best drag reduction effect was selected.Then,the structure of the blade body was analyzed.With the reciprocating speed,cutting edge angle and cutting residual angle as test factors,the central composite test was carried out with the maximum shear force and cutting power consumption as evaluation indexes,and the optimal parameter combination of the bionic blade was obtained when the reciprocating cutter was moving.The simulation test shows that compared with the ordinary blade,the maximum shear force was reduced by 18% and the power consumption was reduced by 15.8%.(4)Bench test.A cutting test device for wild chrysanthemum stem was designed and built.The device was composed of cutting device,stem conveying device and data acquisition device,which could test stem cutting performance under different cutting and conveying speeds.A comparison test was carried out between bionic cutter and ordinary cutter.The average maximum cutting force and cutting power consumption of the imitation tooth blade cutting the whole wild chrysanthemum stem were 366.8 N and19.9 J,respectively,which were reduced by 10.5% and 10.8% compared with the ordinary triangular tooth blade,indicating that the optimized bionic cutter could improve the quality of cutting wild chrysanthemum stem.