Research And Design On Straw Chopper Mounted On Transverse Axial Flow Whole Feeding Combine Harvester

This paper discussed the necessity and importance of using straw chopper mounted on com bine harvester according to the advantage of utilizing straw and its comprehensive utilization sta tus.This paper also surveyed the research process of straw chopper fitted with combine harveste r and summarized the questions and technology problems being faced with while carry out rese arch and design the straw chopper,as for which there are some creative works on straw choppe r fitted with transverse axial full feeding combine harvester.The main works of this paper includes:tests for obtaining mechanical properties of rice stra w referred to tensile strength,tensile elastic modulus,shearing modulus and shearing strength;cons truction of the test bed including transmission scheme,speed control device and the data gatheri ng system;design of key components of straw chopper based on theory analysis and simulation of cutting straw including cutting blade(there were three sorts of cutting blade such as straight blade,trapezoidal blade,curve blade),blade arrangement(two double helical arrangement)and roller for guiding straw;field experiments including two single factor experiments such as the rotation speed of cutting shaft and speed of combine harvester moving using power consumption and pa ss rate of chopped straw as evaluating indicator and multi-factor experiment that includes cuttin g blade,speed of combine harvester moving/feeding rate,rotation of cutting shaft and blade arran gement with three levels.The main conclusions of this paper are as fellows:(1)through mechanical test of rice straw,r ice straw mean tensile strength along axial is 39.27MPa;mean tensile elastic modulus along axia 1 is 1.4Gpa;mean bending shear modulus is 50.31MPa at radial/tangential direction; the peak shea ring force increases with the blade bevel angle increasing;(2)through theory analysis the condition of cutting no grass harassing is that the frictional angle between straw and blade should be s maller than the sliding cutting angle,at the same time the calculation formula of cutting force a re obtained as there exists sliding cutting,which can be seen at expression (4.22);(3)through cutti ng dynamics analysis,the peak cutting force increases with cutting speed increasing on condition th at there is no supporting while blade cuts straw at a high speed; the effective cutting speed of c hopping rice straw suggested is beyond 40m/s on condition no support;the peak value of cutting force is not obviously different from each other as cutting speed at 50m/s while the blade bevel angle is at the range of 20°-50°;(4)the rotation speed of cutting shaft has significant effect on pass rate of chopped straw and power consumption,both of which are increasing with rotation speed of cutting shaft increasing through single factor experiment,at the same time pass rate inc reases slowly as rotation speed is beyond 3000r/min,while power consumption is against that;the speed of combine harvester moving/feeding rate has little effect on straw’s pass rate,but has si gnificant effect on power consumption,both of which are increasing with speed of combine harv ester moving/feeding rate increasing through single factor experiment;(5)the best combination of structure and parameters is C3B3D1A2 using pass rate of chopped straw as evaluating indicator, which means rotation speed of cutting shaft being 3000r/min,average speed of combine harveste r moving being 1.4m/s, blade arrangement being 90°double helical arrangement and blade being kind of trapezoid;the best combination of structure and parameters is B1C1A3D2 using power c onsumption as evaluating indicator, which means average speed of combine harvester moving be ing 1.Om/s,rotation speed of cutting shaft being 2600r/min,blade being kind of curve and blade arrangement being 60°double helical arrangement;the best combination of structure and par ameters is B1C1A3D1 by using pass rate of chopped straw and power consumption as evalu ating indicator with multi-indicator regression evaluating method, which means average speed of combine harvester moving being 1.Om/s,rotation speed of cutting shaft being 2600r/min, blade being kind of curve and blade arrangement being 90°double helical arrangement.Contributions of this paper are as follows:(1)The mechanical parameters of material obtain ed from test and the least speed of cutting off material on condition no support can provide so me meaningful references for research of chopping straw;(2)The theory analysis of chopping str aw can draw on the experience of calculation formula of cutting force deduced as there exists sliding cutting;(3)The results of orthogonal test based on single test can provide some meaningf ul references for designing straw chopper.