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

Existing wheat wide seedling belt seeding is mainly based on the traditional grooved wheel seed metering with the seed leveling device at the end of seed guide tube, there are problems of seed flow disorder, unstable displacement, and seed supply pulse, which affect sowing quality. A pneumatic cone-disc type precision seed metering device for wheat wide seed belt was designed based on the principles of negative pressure seed suction and self-weight seeding. A mechanical model of wheat seed filling was constructed under the action of a cone-disc, and the structural parameters of the main components of the cone disc seeding device were determined. Mechanical analysis showed that the critical negative pressure value required for seed filling and carrying was related to the taper of the seeding disk, seed mass, triaxial size, hole size, working speed and hole graduation circle diameter. EDEM simulation was used to comparatively analyze the impact of different tapers of the cone-disk on the dispersion of wheat populations, and analyze the movement patterns of seeds in the driving layer, stationary layer and drag layer populations. The results showed that when the taper of the seeding disk was 45 °, it can take into account the advantages of good population disturbance and low migration resistance of adsorbed seeds. For different types of holes in the cone disk, seeding performance tests were carried out by using the coefficient of variation of the consistency of the seeding amount in each row, the coefficient of variation of the stability of the total seeding amount, and the coefficient of variation of the seeding uniformity as evaluation indicators. The test results showed that the evaluation of vertical holes with a size of 1.8 mm was better than that of oval holes. The impact of the working parameters of the seed metering device such as seed suction negative pressure and working speed on the seeding performance was explored. The results showed that the seeding amount showed a linear increase trend with the increase of negative pressure and speed. The working speed was 30~40 r/min. When the pore adsorption negative pressure was 5.2~5.6 kPa, the seeding rate can reach 220~290 g/min. the best combination of working parameters was obtained by orthogonal test as working speed of 30 r/min, negative pressure of adsorption of 5.4 kPa, and the evaluation indexes of each test were 1.93%, 1.26% and 9.52%, respectively. Field comparison tests showed that the sowing uniformity of the wide seedling belt of the pneumatic cone-disc seed metering device was improved compared with the wide seedling belt of the outer grooved wheel seed metering device, and can meet the requirements for sowing small amounts of wheat concentrate.