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

In order to solve the problems of high resistance, shallow depth of soil return and easy mixing of wet and dry soil of potato sowing trencher under high speed operation conditions, the streamline curve of yellowfin tuna mandible was used. The horizontal linear element method was used, which can reconstruct the original curve into a three-dimensional surface. A curved grooving device imitating the curve of yellowfin tuna jaw was adopted, which could be adapted to the agronomic requirements of potato planting depth. When the maximum operating depth was 150mm, the sliding cutting principle was adopted, which can determine the maximum cutting edge angle of 132° and the element line angle of 27°. In order to explore the influence of soil lifting angle on the operating performance of the trencher, the operating resistance was taken as the evaluation index, and the single factor test was carried out, which determined that the soil lifting angle of the soil slat was 45°. The length of the upper retaining plate was determined by analyzing the relative displacement of the seed potato when it fell to the surface. The simulation test of dry and wet soil showed that the operation of trencher did not disturb the sequence of soil layers. Compared with the core type furrow opener and the boot type furrow opener, the average operating resistance of the curved type furrow opener was reduced by 18.3% and 33.4%, and the average returning depth was increased by 70.4% and 91.7% under the conditions of furrow depth of 100mm, 125mm and 150mm and operating speed of 3.6km/h, 5.4km/h and 7.2km/h. The field performance comparison experiment showed that the soil moisture content of the curved trench opener was increased by 3.5% and 4.7% compared with that of the coreshare trench opener and the boot trench opener, and the curved trench opener could reduce the mixing of wet and dry soil under the condition of the trench depth of 150mm and the operating speed of 7.2km/h. Compared with the core type furrow opener and the boot type furrow opener, the transverse migration coefficient of potato planting with curved surface furrow opener can be reduced by 9.5% and 10.1%, which can meet the agronomic requirements of potato planting furrow opener.