Development And Test Of Single-Track Self-Propelled Branch Crusher For Hilly Orchards

Fruit industry is an important part of China’s agricultural economy,and is an important relying industry for the local community to consolidation the results of poverty eradication and achieve rural revitalization.Hills and mountains are important production bases for China’s fruit industry,but subject to topography,planting patterns and other factors,the level of mechanized operation is low.Fruit tree branch pruning is an important part of fruit tree management,generates a lot of biomass resources.However,due to the lack of effective crushing and returning equipment after pruning fruit tree branches in hilly orchards,they are generally treated by piling or burning,resulting in waste of biomass resources or environmental pollution.At the same time,the low density of branches and the high number of residual fine branches lead to difficulties in transportation.In this paper,according to the agronomic requirements of branch pruning and crushing to return the fields,based on the single-track transport system,using the method of computer numerical simulation,designed a hilly orchard single-track self-propelled branch crusher.The results of the field test showed that all indicators met the design requirements,which is important for reducing the waste of biomass resources and improving the economic benefits of the fruit industry.The research contents and main conclusions are as follows:(1)Take the branch of apple tree as an example,carry out the shear test.Analyzed the shear strength of different components,and the effect of different moisture content on the shear strength.Measured shear strength of the original branches was 13.21 MPa,and its value showed an overall increasing trend with decreasing moisture content,therefore,the branches should be crushed in time.Also measured the moisture content of the branches was 42.53%and the density was 1044 kg/m~3.Measured physical properties of branch chips:the static friction coefficient between the branch chip and 45 steel is 0.322-0.589,the elastic recovery coefficients between branch chip and branches were 0.1-0.67,the elastic recovery coefficient between branch chips and 45 steel is 0.29-0.8,the angle of repose of the branch chip was39.81°.(2)According to the landscape of China’s hilly orchards and fruit tree planting characteristics,combined with the agronomic requirements of branch pruning,crushing,return requirements,determined the overall design of the hilly orchards single-track self-propelled branch crusher.Determine the power of engine is 2.94 kw,determine the structure form of crushing mechanism is drum type,determine the length of support rod into soil should be greater than 0.63 m.And complete 3D modeling with Solid Works software.Meanwhile,based on PLC control,completed the control system design to realize the remote-control operation of branch crusher,and improve the efficiency of mobile crushing.(3)Analysis of the mode of rail system with different number of sections using ANSYS software,the results showed that,under the condition of rigid fixation of the support rod,the natural frequency of each order decreased with the increase of the number of track sections.Among these,the decrease is more obvious in sections 1-4,when the number of tracks reaches a certain level,the vibration pattern tends to level off,Provided theoretical guidance for track building applications.The vibration level test showed that the difference between the vibration amplitude of the prototype at rest and when moving was not significant,and the vibration amplitude of the crushing operation was significantly higher than that of the no-load state,the maximum vibration is mostly in the left and right direction along the track,with a maximum value of 21.5 m/s~2.(4)By means of the discrete element virtual calibration,passed Plackett-Burman test,steepest climb test and Box-Behnken test in turn,optimized the parameters of the branch chip.Adopt the orthogonal test method to carry out a three-factor,three-level virtual orthogonal test on the three key parameters affecting the effect of branch chip throwing.Take the variance of the number of branch chips in the square grid within 50×50 mm as the evaluation index,get the order of the three factors as:Angle of outlet baffle plate>Rotation speed of the knife shaft>Angle of knife roller paddle plate.When the branch chips are most evenly spread,the three key parameters of the branch crusher are:angle of outlet baffle plate is 30°,rotation speed of the knife shaft is 2300 r/min,angle of knife roller paddle plate is 32°.(5)Field trials have shown that,stable operation of prototype,good effect of branch crushing,small particle size of branch chips,long throwing distance and even spreading.The average maximum throwing distance is 1.52 m.It can provide better branch crushing and return support for hilly orchards,enhance the fertility of soil organic matter and promote the green development of the fruit industry.