Analysis Of Header Structure And Harvest Losses Under Vibrations Of Rapeseed Combine Harvester

The header of domestic rape combine harvester is mostly improved on the basis of the header of rice wheat combine harvester.Although it can realize the basic mechanical harvesting function,the header has multi-source vibration excitation and severe vibration,which leads to poor harvest adaptability and high harvest loss rate.The loss of header falling grain accounts for more than 50 % of the total loss.In addition,the multi-source excitation of the header will also affect the structural strength of the header,cause the local deformation of the header,aggravate the wear of parts,and reduce the working stability of the whole machine.In view of the above problems,this paper carries out the research on the influence of vibration of rape combine harvester on the header structure and falling loss.The research results are of great significance to improve the operation stability of rape combine harvester and reduce the harvest loss,and provide theoretical reference for the design of rape combine harvester header with low loss rate and strong stability.The main research contents are as follows.(1)Taking 4LL-1.5Y crawler rape combine harvester as the research object,using DHDAS dynamic signal acquisition instrument to test the vibration of the header under three different working conditions,and analyze the test data based on time domain,wavelet packet and frequency domain analysis After processing,the research results show that the vibration signal of the header is mainly concentrated in the low frequency range of 0～60 Hz,and the vibration frequency of each exciting force is mainly low frequency.The main vibration sources of the header vibration during the operation of the rape combine harvester are the engine and the cutter,and their vibration frequencies are about27.53 Hz and 8 Hz,respectively.(2)Based on the modal analysis of the header frame by ANSYS software,the first 6natural frequencies and vibration nephogram of the header frame are obtained.At the same time,combined with the multi-source vibration frequency of the header,the influence of the header vibration on its structure is studied.The results show that the excitation frequency of the cutter is 8 Hz,which is in the range of the first natural frequency resonance of the header,and it is easy to cause strong vibration of the header and accelerate the wear of the parts.(3)Selecting “Hua You Za 62” rape variety,based on the default shaker hydraulic shaking table,the rape plants at the suitable harvest period were loaded with different frequencies to explore the key frequency range of large-scale pod and seed drop.The results showed that the maximum frequency range of pod and seed drop of “Hua You Za62” rape was 5～10 Hz,and the highest percentage of seed drop was 3.42 % in this frequency range.The vibration frequency of the cutter is 8 Hz,which can easily cause resonance,aggravate the pod and seed shedding,and increase the loss of the header.(4)Based on the above research,aiming at the vibration source and vibration frequency which affect the structure of the header and the loss of falling grain,the weak part of the structure of the rape header frame and the cutter transmission system are optimized.The dynamic balance performance of the optimized cutter drive system is enhanced and the vibration is effectively reduced.The maximum equivalent stress of the header structure is 112.6 MPa,which is far less than the allowable stress of the structural steel,and meets the strength design requirements.At the same time,the first-order natural frequency increased from 7.23 Hz to 13.09 Hz,increased by 81.05 %,avoided the key frequency range of cutter frequency and rape seed loss,avoided resonance phenomenon,improved the working stability of header,and reduced the seed loss of header.