【作者】 孙齐磊；

【导师】 张晓辉；

【作者基本信息】 山东农业大学 ， 农业机械化工程， 2003， 硕士

【摘要】 小麦在我国农业生产中占有举足轻重的地位。多年来，在粮食播种面积逐年减少的情况下，小麦的播种面积不但没有下降，反而有所增加。提高小麦产量，对于解决中国几十亿人口的温饱问题和改善人们的生活状况都起到了关键作用。随着小麦栽培技术的发展，小麦种植机械化也在飞速前进。以我省为例，2001年，山东省农机总动力达到7689.57万千瓦，机播水平达到了39.16％。纵观全局，小麦条播仍然在农业栽培中占据主导地位，与之相匹配的小麦条播机也被广泛应用。目前国内谷物播种机大多都是以外槽轮式排种器为核心工作部件，结构复杂，排种各行一致性差。型号虽然很多，但由于外槽轮排种器的结构所限，排种脉动性和种子沟内分布不均匀性一直是半精密播种难以实现的主要因素。应用量较小的锥盘式小麦精播机，虽然在播量和种子沟内分布均匀性方面较传统排种器有所突破和提高，但其种子破碎率却高达20%以上[3]，严重影响了种子的出苗率，根本无法实现真正意义上的半精量播种的技术要求。上述两种机型在整体结构上均存在着“一器一行”、结构复杂、排种各行一致性差等问题，臃肿的机体给多行宽幅及耕播联合作业带来了较大的困难。因此研究一种新型的高效、结构简单的播种机显得尤为重要。本文立足于我们小麦生产实际，在深入调查研究有关文献资料的基础上，对气流一阶集排式播种机进行了初步的研究及试验分析。气流一阶集排式播种机是以气流为载体，通过中央分配器实现机械定量、气流一阶分配多行进行播种作业。它的核心部件——集中排种系统，是由风机、种箱、排种槽轮、喷射供料器、输送管道、中央气流分配器等部分组成。风机由播种机相配备的拖拉机动力输出轴驱动向系统提供能量，地轮通过链传动带动排种槽轮，定量的向系统排放种子。通过喷射供<WP=8>料器使得种子与气流混合处形成负压，种子被吸入管道并与气流混合。料气混合物进入增压管后，产生涡流，压力增高，最后由中央分配器统一进行排种。种子能够做气力输送的前提条件是管道内气流速度大于物料种子的悬浮速度。为确定物料种子在管道中的运动形式，对管道中气力输送的种子做动力学分析，确定其运动方程，研究在管道中压力损失情况。首先假定输送比，初定气流速度，由农业技术要求确定排种量，从而确定风量，计算得到管道的直径。计算气流和物料的混合体在管道中的压力损失，以此为依据确定风机所需要的风压。由于影响系统的因素很多，当改变任何一个参数时都需要重新计算，为了避免重复繁琐的人工计算，笔者利用VB语言编写了压力损失计算程序，用户只需输入基本的参量，计算机就可以完成复杂的计算，最后得到结果，这样原本复杂的计算变得既简单又快捷。研究分析气流分配器的结构形式，确定不会产生涡流和滞流的Ⅱ型气流分配器，并且确定其结构尺寸。为了更加直观的观测和设计，笔者绘制了气流分配器的三维造型。 通过试验测定试验用种子的悬浮速度，校核初定的气流速度，从而确定管道内风速。考察影响排种系统性能指标——各行播量一致性的因素及水平，确定影响因素有槽轮的转速、气流速度、弯管的弯曲半径、铅垂加速管的长度、增压管的长度及节距等因素。通过试验校核风机的风量和风压，最后确定风量为2930.4m3/h，风压为96219Pa。更多还原

【Abstract】 This paper focally states the study and Study and test analysis on the one-step Seed-centralized pneumatic drill on the basis of analyzing China current wheat-planting policy, the cultural techn- ique of drill sowing and the present situation of correspond- ing pneumatic drill.Wheat takes a decisive place in agricultural production of our country. For many years, sown area of grain has been decreasing little by little, while that of wheat has been gradually increasing. For China, raising output of wheat plays a key role in solving tens hundreds million of people’s life conditions.With the development of wheat-planting technique, wheat planting mechanization is developing rapidly as well. Take our province as an example, general farm machinery power reached 7685.57KW. The level of mechanical seeding reached 39.16%. By and large, wheat-drill also takes dominating role in agriculture planting and suited seed drill is also been taken into practice. At present grain drills generally take fluted feed as their core parts, but its structure is complicated, coherence in each row is poor. Conical-dish wheat precision drill applied less improves in the way of distributing equality, but its staving rate reaches 20%. Thus it affects the rate of emergence seriously and cannot realize the demand of semi-precision drilling. Both of above drills exit many questions, such as "one dispenser one row", complicated structure and poor coherence in each row and so on. Therefore, it<WP=10>is necessary that developing a new kind of efficient drill. One-step seed-centralized pneumatic drill takes air current as carrier, realizing fix quantify mechanically and one-step multi-rows air seeding working. Its core parts Seed-centralized system is consist of fan, seed box, fluted feed, eject enricher, pipes, center air distributor and so on. Fan is driven by PTO of tractor suited with drill and provides energy to the whole seed-centralized system. Fluted feed is driven by wheel with chain wheel transmission, distributing seeds to the seed-centralized system quantificationally. Seeds are sucked into the pipe where exits minus pressure by eject enricher. After entering into supercharger pipe, seed-air mixture produces backset and pressure increase. Finally, seed-air mixture expel from center air distributor under effect of centrifugal force.The precondition that air current can carry seeds is the air velocity is larger than that of the suspend velocity of materiel. In order to ascertain the movement form of seeds in pipe, we make kinetic analysis to seeds in pipe. We make sure movement equation of the seeds and study pressure expense. First we presume feeding rate, ascertaining the velocity of air current, ascertaining the feeding quantity by farm technical demand and ascertaining wind quantity, calculating the diameter of pipe. By calculating pressure expense, we ascertain the working pressure of fan. Because many factors affect the capability of the system, we have to calculate the data over again while changing anyone of factors. In order to<WP=11>avoid complicated manual work, penman programme pressure expense with VB language. User only input some basic parameter, the computer can complete complicated calculating works. Thus, complicated calculating works originally become easy as well as shortcut.By studying the form of center air distributor, we ascertain typeⅡ center air distributor which cannot produce backset and backair and ascertain its structure size. In order to observe and design more easily, penman protracted three-dimensional drawing.We determine the suspend velocity of seeds used in test, verifying air velocity presumed formerly and ascertain air velocity in pipe. Reviewing the guideline affected capability of seed-centralized system, we ascertain affected factors: rotate speed of fluted feed, air velocity, radius of curving pipe, length of vertical pipe, length of supercharger and screw pitch of supercharger. We verified wind quantity and pressure of fan by testing. As a result, the wind quantity of更多还原