ass日本风韵熟妇pics男人扒开女人屁屁桶到爽|扒开胸露出奶头亲吻视频|邻居少妇的诱惑|人人妻在线播放|日日摸夜夜摸狠狠摸婷婷|制服 丝袜 人妻|激情熟妇中文字幕|看黄色欧美特一级|日本av人妻系列|高潮对白av,丰满岳妇乱熟妇之荡,日本丰满熟妇乱又伦,日韩欧美一区二区三区在线

The soil in the middle and lower reaches of the Yangtze River is sticky and hard. The quality of traditional straw returning tillage machine is not ideal, and the knife roller is easy to be twisted and the power consumption is large. To solve the above problems, a sixhead spiral straw returning cultivator’s knife roller was proposed. Secondary cutter blade was designed, and the structure of knife roller and working principle were illustrated. The reduction degree of the secondary cutter blade and the major working parameters were analyzed. The results of experiment showed that the influence of factors on power consumption and straw burial were significant, which from large to small were rotating speed of knife roller, tillage depth, working speed and tillage depth, working speed and rotating speed of knife roller, respectively. The influence of factors on straw crushing and soil pulverization were significant, which from large to small were rotating speed of knife roller, working speed and tillage depth. The optimum value of tillage depth, working speed and rotating speed of knife roller were 12.7cm, 0.7m/s and 273r/min, respectively. The results of verification experiment showed that the power consumption, rate of straw burial, rate of straw crushing and soil pulverization were 31.9kW, 93.1%, 87.5% and 78.3% when working on the optimum values. The errors between the predicted values were 4.7%, 1.4%, 1.3% and 5.8%, respectively. The results of contrast experiment showed that the power consumption and the rate of straw burial of six-head spiral straw returning cultivator were 8.8% and 2.3% lower than that of cultivator for straw returning in paddy field and dry land, respectively. However, the rate of straw crushing and soil pulverization were 3.0% and 6.1% higher than that of the latter. The research results can provide reference for the design and improvement of straw returning tillage machine in the middle and lower reaches of the Yangtze River.