Dynamic Modeling And Analysis Of Passion Fruit Pulping Device

Due to the low fresh fruit value of passion fruit and other berry fruits,pulp should be extracted to make products with longer preservation time and higher value.At present,there is no mature automatic device for extracting passion fruit pulp in the market,and there are some problems such as difficult extraction,low production efficiency,poor safety and easy crushing of fruit pulp.Therefore,it is of great significance to design and develop an automatic passion fruit pulping device.In this paper,a new type of passion fruit pulping device is designed,which can effectively solve the problem of automatic pulping.The pulping device is composed of a fruit cutting mechanism,a pulping mechanism,a fruit pulp collecting mechanism,a motion module and an electronic control module,among which the pulping mechanism is the core component of the pulping device.Based on the theory of plate and shell vibration,the theoretical expressions of kinetic energy,bending and torsional potential energy,centrifugal potential energy and work performed by external forces of the rotor system were obtained.The dynamic model of the system was established through theoretical derivation and combined with Hamilton principle,and the kinetic equation was discreteted by Galerkin modal truncation method.The kinetic differential equation of the sliced rotor system under the excitation of multiple loads is obtained,and the dynamic relationship between the parameters of the system is revealed.Considering the coupling effect of flexible deformation between the flexible slice and the fruit body,the finite element method was used to analyze the contact characteristics of the assembly of the grinding mechanism,and further study the changes of stress and contact characteristics of the grinding mechanism under the conditions of different rotation speed,slice thickness and different contact tightness between the flexible slice and the inner wall of the fruit body.The research shows that,The rotor speed of the flexible slice and the contact compactness between the slice and passion fruit(compression degree)have a great influence on the contact stress and deformation of the cut slice,while the thickness of the slice has a little influence on the contact stress of the cut slice,but a great influence on the contact deformation.According to the comprehensive analysis,the optimum conditions for digging are250r/min,0.3mm and 12 mm for rotation speed,slice thickness and contact tightness,respectively.The first 30 order natural frequencies and modal shapes of the pulping mechanism were obtained through the whole machine modal simulation.The changes of each order modal shapes of the mechanism and the parts prone to vibration were analyzed,and the types of exciting forces that might cause the vibration of the pulping mechanism were analyzed.The vibration characteristics of the grinding mechanism were analyzed,and the vibration signal time-domain diagram and spectral diagram of the grinding mechanism were obtained under different rotation speeds and different contact tightness(depth of downward pressure),and the influence law of each parameter on the vibration acceleration response of the grinding mechanism was analyzed.The prototype experiment of the whole machine of the passion fruit pulping device was carried out to test the extraction rate of passion fruit by the pulping mechanism under different working conditions,and the average pulp extraction rate under each working condition was above 90%,which directly verified the feasibility of realizing the pulping target of the passion fruit pulping device.The deformation and vibration acceleration response of the pulp slices under different working conditions were tested after the passion fruit was dug out.The accuracy of the simulation results was verified by comparing with the simulation results,which laid a foundation for the optimization and engineering application of the passion fruit pulp digging device.