Experimental Research Of Rape Combine Optimum Harvest Time Prediction And Stem Breakage

The planting area of rapes in China is generally 7 million hectares which accounts for about 1/3 of the world, while the outputs of rapes are 13 million tons.However, China is still undeveloped in rape mechanization at present and at a relatively low level in comparison to that of America and German, especially in harvesting mechanization which develops slowly. As for the researches of the features of the oil plants in the mechanized harvesting, the thesis does the studies from two aspects: one is the rape pods and the other is the rape stalks. Recently, the rape combine optimum harvest time is determined through human’s own observation on the seeds and by experience. There hasn’t yet been a scientific method to predict the optimum combine harvest time. The imprecision in the prediction and judgment for the maturity of the rapes result in the lack of scientific basis for the distribution of the rape combine harvester which further leads to the improper distribution of the agricultural machine resources in every region and the low utilization ratio of the agricultural machines. The threshing and separating device is the crucial part of performance. The threshing spike teeth’s impact effects on the rape pods lead to their cracking, breaking. Then the rape seeds are separated from the rape pods. Inside the threshing space, the flow materials do the spiral movements which is long in the duration of threshing, serious in the stalks breakage. What’s more, among the threshed materials, there are many shells of the pods, broken stalks and other impurities which increase the difficulty of cleaning and the loss rate of harvesting.In conclusion, the lacking in the study of material properties of the rape restricts the development of the mechanization of rape harvester in China.Thus, based on the material properties of the rape, the prediction about the rape’s maturity during the rape combine harvest time will be carried out and the suggestion for determining the optimum combine harvest time of the rape will be made in this thesis, which provides the basis for the the distribution of rape combine harvesters and regional production organization. In addition, the experiment for the performanceof rape stalk breakage is operated so as to know the laws about every factor’s influence on the degree of the stalk breakage and the optimum working parameters of the rape stalk crusher, which will offer the references for studying the rape combine harvester and thresher devices of higher efficiency and higher performance.The main research contents of the program includes:(1)A way to predict the maturity of the rape is put forward. The RGB color processing test of rape pods is done. By the use of the software matlab, the mathematical model between the H values of the rape pods’ hue and the growing days after 204 days since rapes are planted is built. The pods’ hue-- H value achieves judging the maturity of rapes.Based on BP neutral network, the model of rapes maturity is built, and also the prediction of the maturity of rapes is made.The experiment shows: the hue of rape pods’ surface-- H value is in an increasing tendency along with the day. The predicted H values of rape pods surfaces of the thirteenth day and fourteenth day are respectively 64.4640, 64.4723 while the real test measured values are 64.4296, 64.4307, with the differences of about 0.053%and 0.065%. Therefore the predicted values is nearly equal to the real measured values.(2)By the use of self-made experimental equipment for rape stalk breakage performance, the experiment for the performance of the rape stalks breakage based on the factors such as the feeding quantities, the rotating speeds of the tangential flow cylinder, the distance between the crushing teeth, the diameters of the rape stalks is operated. And the single-factor experiment is conducted to explore the laws of every factor’s influence on the broken degree of rape stalks. The experimental data on the breakage degrees of the rape stalks can be analyzed by the orthogonal design-direct analysis method, so as to get the work parameters of the rape stalk crusher when the degree of the rape stalk breakage is minimum.The results of the single-factor and multi-index experimental show that the distance between crushing teeth and the rotating speeds of the tangential flow cylinder are the principal factors influencing rape stalk breakage degree; while thefeeding quantities has little influences on the breakage degree. As the feed quantity increases, the cylinder spike teeth more fully contact with the rape stalks which makes the mass fraction of the stalks with the length less than 70 mm large among the broken stalks. That is to say, during the threshing and separating of combine harvesting, excessive feeding quantity will result in more stalks and impurities among the threshed materials. Besides, that has the greatest influence on the longest ten stalks among the threshed materials is the stalks’ diameters. As the diameters increase,the length of longest ten stalks decrease, which indicates that in the process of rape stalk crusher’s threshing, the longer the diameter is, the less the amount of the stalks is, the more broken the stalks are under the strikes of the spike teeth. Therefore, the relatively more broken stalks among the threshed materials of the combine harvesting are usually derived from the stalks with longer diameters.The results of the orthogonal experiment show: on the condition that the feeding quantities of rape stalks under 40g/s, the distance between the crushing teeth 40 mm,the rotating speed of the tangential flow cylinder 750r/min, the diameter of the stalks7-9mm, the broken rate of the threshed stalks can be the lowest.