Study On The Maize Threshing And Cleaning Mechanism With Low Loss And Anti-blocking And Its Linkage Control

The mechanized harvesting of grain in China is developing in the direction of high efficiency and intelligence.In the arena of corn mechanized combined harvesting,the main development orientation is high-efficiency direct grain harvest.But using direct grain harvesting will lead to a high corn grain crushing rate and a high risk of clogging in the threshing and cleaning process because of high moisture contained in corn kernels and stalks(more than 28%),that has developed into a bottleneck that hinders the promotion of efficient corn direct harvest technology.In view of the problems,this paper has carried out the quantitative research on the damage of corn kernel,the analysis on the movement of corn kernel group with variable amplitude sieve,also diagnosis research on the threshing load status based on the acceleration signal analysis in corn kernel direct harvest and.The paper has creatively put forward the concave clearance adjustment mechanism based on the two-way stay wire clamping principle and initially carried out the threshing analysis on the joint control strategy of of the threshing and cleaning process.The specific research work of this paper are as follows:(1)The surface damage features of the direct harvest corn grain obtained under different operation parameters were extracted,fused and measured in length and area based on the image processing technology.The quantitative evaluation index of single corn kernel damage was proposed and analyzed.The results showed that the the proposed corn kernel damage quantitative index could effectively measure the corn grain damage and the concave clearance besides the operating speed had a significant effect on the kernel damage.(2)The low-damage concave sieve of corn was developed with the arc structure.A threshing clearance fast adjusting mechanism based on the principle of two-way pull wire clamping was innovatively developed.Meanwhile a low loss anti-blocking threshing and cleaning test bench for maize was designed and processed.The variable amplitude mechanism at the front of the sieve was optimized,and the angle of the chute at the front of the sieve was changed by the lifting of the electric push rod.That made the continuous adjustment of amplitude come true.(3)The time-frequency analysis and wavelet packet analysis were carried out on the acceleration signals collected in the field test.It was found that the load fluctuations were all below 50 Hz,which was consistent with the actual operating conditions of the machine.The vibration intensities of 9 groups of signals were calculated.The results showed that the intensities were 4-10 times higher when the material was fed in than not loaded.Evidence showed that the intensities changed obviously with the threshing state,which can be used as a quantitative index to judge the threshing state.(4)The relationship between the backward moving speed and sieve penetration rate and the grain loss along with the angle of the chute at the front of the sieve were studied based on the EDEM discrete element simulation.The results show that the backward moving speed of the material increased with the amplitude of the front of the sieve,so would the increment of the speed increase.The speed increment when the chute angle increased from 42 ° to 47 ° was approximately 4 times as much as the increment when the chute angle increased from 2 ° to 7 °,and the loss of grain was significantly increased when the chute angle was greater than 37 °.(5)The process of threshing and cleaning under different operating load conditions and their correlations were studied and analyzed,and the anti-blocking control strategy for threshing and cleaning was preliminarily formulated.The linkage control has been initially realized through Siemens PLC,sensors,stepper motors,electric push rods,etc,which could effectively prevent the clogging of threshing and cleaning.A preliminary threshing and cleaning linkage anti-blocking control system was constructed and a simulation demonstration of the joint control strategy was realized using Siemens PLC,weighing/acceleration sensor,stepper motor,electric push rod,etc.,which laid the foundation for the further optimization of the joint control strategy.Reducing threshing damage and harvest loss and preventing blockage in threshing and cleaning process were the common requirements of high-efficiency combined harvest.Therefore,the research work of low loss and blocking prevention carried out in this paper was not only had a direct reference to promote the application of corn direct harvest technology,but also had a universal reference value to solve the problems of damage,loss and blocking faced by other grain high-efficiency mechanized combined harvest.