| Citrus is an important fruit in China,and pruning of citrus trees is an important operational aspect of citrus production.Reasonable pruning can promote photosynthesis in citrus trees,improve citrus production and quality,and at the same time reduce production costs.At present,China’s orchard pruning machine has low pruning efficiency,single tree pruning shape,and is not suitable for hilly area citrus tree orchards.In response to the above problems,this paper develops a hilly area citrus tree pruning machine based on the existing fully hydraulic tracked remote-controlled power chassis to achieve adjustable height,width and angle of citrus tree pruning and improve pruning efficiency.The main research contents and conclusions include:(1)The overall structure plan of the hilly citrus tree pruner was designed.Based on the pruning requirements of citrus orchards in hilly areas,the functional and performance requirements and design parameters of the machine were proposed;according to the actual growth of citrus trees,different cutter and frame solutions were compared,and the combination of circular saw blade cutter and reciprocating cutter was selected for the cutter,and the railslider frame was selected for the frame,which has low friction resistance and high load-bearing capacity;the structural scheme of the machine was determined,and the working principle of the pruner operation was elaborated.principle.(2)The bench test of circular saw blade cutter was carried out.The single-factor test was conducted to investigate the influence of sawing speed,feeding speed and number of teeth of saw blade on the sawing effect of the cutter with sawing torque,power and trimming quality grade as evaluation indexes.When the sawing speed is 1500r/min,the feed speed is 0.3m/s and the number of teeth of saw blade is 120,the trimming power consumption of circular saw blade cutter is smaller and the quality of trimming section is smooth and flat,the peak torque is 1.87 N and the peak power is 235 W.(3)The design and analysis of key components were carried out based on the overall structure of the trimmer.The kinematic analysis and mechanical analysis of the reciprocating cutter were completed,and the movement speed and torque of the reciprocating cutter moving blade at any point were different;the static simulation of the disc saw blade cutter and frame was carried out using ANSYS software,and the results showed that the maximum deformation of the disc saw blade cutter was 0.011 mm and the maximum stress value was 4.5MPa,and the maximum deformation of the frame was 2.29 mm and the stress The maximum value is151.86 MPa,the strength and stiffness meet the design requirements;the sixth-order modal analysis of the circular saw blade cutter and frame,compared with the external excitation frequency,the results show that no resonance will occur,and the stability is good.According to the topographic characteristics of citrus orchards in hilly areas,combined with the force analysis of the trimmer,the stability analysis of the trimmer when driving on longitudinal and transverse slopes was carried out,and it was deduced that the longitudinal and transverse limit tilt angles were 60° and 53.57° respectively,and the trimmer would not overturn when driving on slopes;the limit slip angle was mainly related to the tire structure parameters and the operating terrain environment,and the longitudinal and transverse limit slip angles were 31° and 28.34°respectively,and the trimmer would not overturn when driving on slopes,28.34°,the trimmer will not slip when driving on the slope,and the stability of trimmer driving on the slope meets the requirements.(4)The design and simulation of the hydraulic system of citrus tree pruner in hilly areas were completed.According to the working principle of the pruner,the hydraulic system design was completed and the calculation and selection of hydraulic components were carried out.HSG bidirectional hydraulic cylinder was selected for the lifting cylinder,ROB hydraulic cylinder for the rest of the cylinders,BMM8 hydraulic cylinder for the circular saw blade cutter and BMM32 hydraulic motor for the reciprocating cutter;AMESim software was used to simulate the hydraulic system to verify the hydraulic cylinder circuit and hydraulic motor The results show that the hydraulic cylinder runs smoothly and the hydraulic motor can provide the required speed and torque of the trimmer stably,meeting the design requirements.(5)Completed the prototype of citrus tree pruner in hilly area and carried out the functional verification of the prototype.The functional commissioning of the pruner was carried out to verify the pruning height,width and angle adjustment functions.The hydraulic cylinder of the pruner did not stall during the commissioning process,and the overall operation was smooth and the cutter speed reached the expected effect.Field experiment results showed that the operation of the trimmer was stable,the average missing cut rate was 10%,and the average qualified rate was 89.8%.The quality of the trimmer section was good,and the efficiency of the trimmer was improved to meet the design requirements. |
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