Design And Experiment Of A Reverse Flexible Harvesting Device For Fresh Corn

Fresh corn is considered as a cash crop integrating grain,fruit,vegetable and forage,and has high economic value.At present,fresh corn in China is mostly harvested manually,but with the significant increase in the planting area of fresh corn,the efficiency of manual operations is too low and the cost is too high.The existing fresh corn harvesting machinery commonly suffers from severe ear damage and high grain breakage rate during operation.To address these issues,this article will focus on the research of key technologies for fresh corn harvesting devices based on the reverse ear picking principle,providing a theoretical basis for subsequent research on fresh corn harvesting machines and technologies.This article mainly conducts the following research work:(1)Conduct physical parameter measurement and mechanical characteristic analysis of fresh corn plants during the harvest period,and determine the physical parameters of fresh corn plants during the harvest period,laying the foundation for the construction of a simulation model for fresh corn plants.The analysis of the tensile and compressive mechanical properties of fresh corn stalks during the harvest period provides theoretical support for the design of the ear picking device.The picking force of fresh corn plants during the harvest period was measured using a reverse picking method from top to bottom,which is opposite to the traditional mechanical picking method.The dynamic and static picking force tests were conducted between the stem and fruit stem,as well as between the fruit stem and ear,providing data support for later simulation.(2)In response to the low loss requirements of fresh corn harvesting equipment,the collision process between the ear picking device and fresh corn ears was analyzed,and a reverse flexible fresh corn ear picking device was designed.Reverse ear picking has low ear picking ability and weak damage to fruit ears.Flexible structures and materials can effectively reduce the collision impulse between the ear picking device and the ear,thereby reducing the damage rate of fresh corn kernels during harvesting and achieving the goal of low loss harvesting.Completed the structural design of the key components of the ear picking device,and determined the structural parameter range of the ear picking device: the number of ear picking claws was 3-5,the speed of the ear picking claws was 1.5~2.5 m/s,the thickness of the flexible body was 2~6 mm,and the feeding speed of the stems was 0.5~1.5 m/s.(3)The ADAMS software was used to simulate and analyze the harvesting process of fresh corn,and the rationality of the reverse flexible fresh corn harvesting device design was verified.Firstly,the dropping conditions of fresh corn ears were determined through simulation.Then,the contact forces between the rigid picking mechanism and the flexible buffering picking mechanism and the fresh corn ears were analyzed under different picking claw speeds and stem feeding speeds.The rationality and effectiveness of the reverse flexible fresh corn picking device were verified,and the optimal picking parameter combination was obtained: the speed of the picking claw was 2m/s,and the feeding speed of the stem was 1m/s.(4)In order to further analyze and verify the low loss effect of the reverse flexible fresh corn ear plucking device,a comparative test of fresh corn ear collision was carried out at the operating speed of the harvester between the rigid ear plucking mechanism and the flexible buffer ear plucking mechanism,and the parameters such as the peak collision acceleration,collision time,collision impulse,etc.were collected during the harvesting process to calculate the grain crushing rate.It was found that compared to traditional rigid picking mechanisms for corn harvesting,flexible picking mechanisms with buffer springs and flexible contact surfaces can effectively change the collision force with fresh corn ears,achieving the goal of reducing the rate of grain breakage during harvesting,and verifying the low loss effect of flexible picking mechanisms in the picking process.(5)To determine the optimal working parameters of the reverse flexible fresh corn picking device,a bench test was conducted on the fresh corn harvesting and picking device,and the optimal picking operation parameters were obtained: the picking claw speed was 2.11m/s,the number of picking claws was 4,the flexible body thickness was 4.52 mm,the stem feeding speed was 1.04m/s,the corresponding grain damage rate was 0.128%,which was much lower than the national standard(0.5%),and the ear impurity rate was 0.3%,which was much lower than the national standard(2%)and meets the requirements for low loss harvesting.