Research On Key Technology Of Pre-compacting And Shaping Based On Large Rectangular Of Corn Straw Picking And Baling Machine

The yield of corn ranks the first in China.Corn stalk,the residue from corn production,is considered as a valuable biomass resource.With the increasing of yield,the comprehensive utilization of corn stalk has been paid close attention in the agricultural production in China.In recent years,in order to respond to the call of the country and actively implement the"five modernization"plan put forward by the government,more and more researches on straw resources have been carried out.However,there are still some deficiencies in the compression theory.Based on a new type of top-feeding hydraulic square baling machine,this paper conducted a pre-compacting of corn stalks under low density and a performance test based on this new baling machine.Taking Liudan NO.301 corn stalks as the research object,the closed compression test,the recovery characteristic test and the falling test of the formed stalk blocks were carried out respectively by the WDW-20microcomputer controlled electronic universal testing machine.The main research contents and conclusions are as follows:(1)In this paper,a compression chamber with 5 different sizes is designed,which is 200mm×400mm,300mm×400mm,400mm×400mm,400mm×400mm,500mm×400mm,600mm×400mm.The compression chamber is used in conjunction with the universal tensile and compression testing machine to provide equipment basis for subsequent tests.(2)By fitting and analyzing the experimental data obtained by corn stalk compression,this paper determined the effects of different initial densities and different compression cross-sectional areas on the stress-strain and pressure-compression density during compression.Mathematical models of stress-strain and pressure-compression density of corn stalks with different compression cross-sectional areas and different initial densities during compression were obtained.This analysis provides a theoretical basis for the design of the compression piston and the whole compression chamber of the baling machine.The analysis results showed that there was a strain boundary point and a compression density boundary point during the entire compression process.When the strain was in the range of 0-0.9,the initial density and compression cross-sectional area had little effect on the stress-strain.When the compression density was less than 0-100kg/m~3,these two factors had little effect on the pressure-compression density.(3)The recovery characteristics of corn stalks were studied by response surface method.The experiment was conducted with the moisture content,initial density,compression displacement and compression cross-sectional area as experimental factors,the recovery amount,peak compression force and post-compression density as the test indexes.The regression model of test factors and test indexes was established,and the influence of each factor on the test indexes was analyzed.The optimal compression parameters were obtained through calculation,including initial density of 60kg/m~3,moisture content of 20%,compression displacement of 225mm and compression cross-sectional area of 400mm×400mm,which provided theoretical basis for subsequent tests.(4)Based on the baling machine,the falling test of the formed stalk blocks was carried out.Taking moisture content,compression section area,falling density and falling height as the test factors and mass loss ratio as the test index,the regression model between each factor and test index was established by response surface method and the influence of each factor on the test index was analyzed On the basis of stalk blocks recovery test,the optimal falling parameters of stalk blocks were calculated as moisture content 20%,compression section 400mm×400mm,falling density130kg/m~3 and falling height 563.5mm.The test results provided theoretical guidance for the structural optimization of the new type of top-feeding hydraulic square baling machine and the design of the pre-compression integral device.(5)The test results obtained in this paper provide some help for the subsequent pre-compression chamber size design and pre-compression device design.The optimal results obtained through the test can be used to calculate the key parameters of the pre-compression device quality,power configuration,etc.