Study On Working Mechanism And Experimental Of Rotary Tiller For High Straw Returning

The middle and lower reaches of the Yangtze river is the main producing areas of rice in China,rice planting area accounts for about 60% of the nation's total.Along the river on both sides of the north of the Yangtze river system,a year is given priority to a two-year system mainly: rape-rice,wheat-rice,green manure-rice;south of the Yangtze River to a three-year-based system: rape-early rice-late rice,barley-green manure-early rice and late rice,etc.The region of high temperature and humidity,rainfall,rain heat the same,and cause a serious plant diseases and insect pests,straw buried field to help eliminate weeds and plant diseases and insect pests,reduce pesticide seems to reduce the agricultural non-point source pollution,improve soil organic matter content;Just returning ground cover is the most direct,the most effective treatment.After the previous harvest crop in this region,farming season is on pressing while the amount of straw is considerable and straw collection transport costs high,the residual field of straw is higher and higher,the conventional plough digging in hard,so most of the straw is burned in situ which cause serious ecological environment pollution.The rotary buried already showed alternative advantages,but due to straw digging mechanism is unknown,affect the work quality,energy consumption factors,lack of detection means,the power consumption of the rationality of the performance parameters of the machine structure,the in-depth study of performance and fuel economy also stays in the stage of qualitative simulation and indoor bench test,an urgent need to deepen the theoretical study and field test.Based on the systematic analysis and summarization of the related research on the domestic and foreign straw burying rotary tiller,this paper aims at the characteristics of grain crops in the middle and lower reaches of the Yangtze River in China,and the research is on the high crop straw counters-field sequence tillage machine designed and developed by Huazhong Agricultural University.Based on the combination of theory and experiment,the working mechanism and field experiment were carried out to study the combined knife roller,the key components of the straw burying rotary tiller which can bury crop straw not only in wet land,but also in dry land.The study also optimized the spiral cross knife the core components of the machine.The main research content is as follows: 1.The soils,rape paddy field and maize dryland soil cultivated in the middle and lower reaches of the Yangtze River were studied.The main performance parameters were tested.The soil texture,organic matter,soil density,soil bulk density,water content,porosity,soil bound water content,and the shear strength of soils in three types of soils were studied by triaxial shear test.These tests provide theoretical reference basis for the design,working parameters selection and field experiment of the key components of the straw burying rotary tiller.2.The mathematical model of the spiral cross knife o-the core working part of the combined blade is established to calculate and analyze the operating characteristics.The dynamic sliding cutting Angle(25 to 25.3 °)of the spiral cross knife(hereinafter referred to as the horizontal knives)is less than the friction angle between the straw and the horizontal knife,and there is no tillage clearance leakage gap in the axial arrangement,it is the main reason of the knife shaft not knit grass when working in the stubble straw field;the standard rotary tiller IIT245 has the axial lateral pushing effect on the soil during the tillage process.The horizontal combined with the IIT245 rotary tiller could counteract the lateral thrusting effect to the soil.This is the main reason for the high flatness of the surface after the machine operation.High crop straw returning in the field has three stages:(1)The straw wrapped in the edge of the knife,was cross knife pressed,dragged into the tillage layer of soil during the process of soil was cut-in by horizontal knife.(2)During the process of throwing the soil,the straws wrapped in the cutting edge of the spirals are quickly separated from the helical scissors and permanently immersed in the tillage layer under the action of their own centrifugal force,soil friction and soil flow from the horizontal knife.(3)There is a portion of soil back-cast by spiral cross knife hit the trailer after landing to cover the surface,increasing the depth of straw buried.In the first stage,the dynamic cutting angle is relatively large(71.735 °),and the surface of a large number of straw wrapped edge,so the soil is high resistance,which is the main reason why the machine operation process power consumption is higher than the traditional rotary tiller;In the second stage,the dynamic cutting angle(80.275 °)is much larger than that between the straw and the transverse blade,which is beneficial to the straw as soon as possible.It is also beneficial to the soil after the third stage.3.A series of field trials were carried out on the high-cropping field tiller roll-helical knife roll and combined knife roll developed by Huazhong Agricultural University.(1)The field experiment of rice,rape and green manure was carried out to the combined knife roller as the research object,and the adaptability of the combination knife to the vegetation was verified.(2)The main factors that affect the quality of the blade roll are the rotary speed of the blade,the unit forward speed and tillage depth.In order to clarify the influence of the above three factors on the quality of the work,the field experiment was carried out by using the L9(34)orthogonal test table.The results of the test results show that the primary and secondary factors affecting the quality of the work in the order are the tillage depth,the forward speed and the rotary speed.The effect of three factors on straw burial rate was as follows: the effect of tillage depth was very significant,and the effect of advance speed was significant,and the effect of rotary speed was not significant.The optimum parameters of the combined tool roll are: the forward speed of the tractor is 0.43 ~ 0.93 m / s,the rotary speed of the knife roll is about 330 r / min.(3)The contrast tests of field operation about the tillage machine tools whose critical component respectively are the traditional knife roller,screw knife roller,combined knife roller were carried out.The test results show that the tillage depth of the traditional rotary knife is lower than the other two knife rollers,its straw buried also by poor performance,and can not meet the national standard requirements;while the combined knife roller buried vegetation cover rate above 94%,and tillage depth is greater than 20 cm,and its operational tillage deep is stability.The results showed that the working quality indexes of the combined knife such as flattening,coverage,tillage and surface roughness were better than those of the other two kinds of knife rolls.That is,the combination knife roller operating quality best,straw buried performance is best.(4)Study on the Practical application of the cultivating roller for high straw returning only in paddy field and the machine used both in paddy field and dry land was respectively conducted.Through series of experimental studies,the results show that compared with the cultivating roller for high straw returning only in paddy field,the machine used both in paddy field and dry land is more suitable for high straw returning of the main food crop rice and rape,wheat and son on both in paddy field and dry land.Of the buried field,machine field adaptability is strong,good buried performance.4.The soil movement pattern was analyzed,and the soil movement trajectory was obtained.The change law of soil velocity and time,displacement and time,force and time were obtained.The soil is thrown back by the knife roller in the course of operation;The analysis of the law of straw movement was carried out to obtain the trajectory of the straw,and the change rule of the straw velocity and time,the displacement and time,the force and time were obtained.The straw was buried by the soil thrown back when pressed down by the knife roller during the working process of the machine;The research analyzed the working process of the combined knife,obtained the law of the roller movement,obtained the law of the speed and time of the knife roll,the change of the displacement and time,the force and the time,and the law of the torque of the knife roller.The resistance of knife roller came from the soil rapidly reached the maximum when the machine would embed soil,and the power consumption was also the largest equipment.5.The contrast tests about the straw returning rollers which respectively installed the traditional knife roller,spiral knife roller,combined knife roller were conducted.The tests used wireless telemetry technology and took advantage of the power-output shaft torque integration transducer.The experimental results show that the operating quality indexes of spiral knife roller and combined knife roller such as straw coverage rate,tillage depth,tillage stability and surface roughness are higher than the national standard while the traditional straw coverage rate is not up to the standard.The traditional rotary tiller has lower power consumption,but the ability to deal with the straw is poor;the combination roller's operation quality is the best,but its power consumption is slightly higher.6.In order to keep the good high crop straw buried effect of the knife roller,at the same time in order to improve the strength of the knife roller,reduce the power consumption of the knife roller assignments,the optimal cutting angle of the spiral blade was determined.On the basis of theoretical analysis,the combination of the knife roller is improved,mainly on the spiral cross-section size of a certain adjustment.The research results also show that it is better to replace standard knife block for the original knife roller in the middle of the cutter disc in order to improve the generality and reduce cost.7.The research designed four kinds of horizontal knives with different cutting angles to test the quality and power in paddy field and dryland field.The relative parameters of field tillage before and after tilling were measured,and the optimal cutting angle was obtained by field performance.8.The experimental tests in the field were carried out on rice straw with high yield of 90.6 cm and 49.2 cm using the straw returning both in paddy field and dry land after optimizing.And after tilling,the tillage depth was 17.9 and 24.0 cm,respectively.The average vegetation power was 89.8% and 86.6% respectively.The vegetation burial rates were 99.8% and 97.4% respectively.The average surface roughness was 1.9 and 1.4 cm,the average power consumption was 26.6 and 28.9kW,and the maximum power consumption was less than 29 kW.Field operation quality and power consumption indicators are in line with design targets,and compared to the previous power consumption reduced,to achieve the desired design goals.