Study On Separation Of Rethreshed Stripped Mixtures And Their Cleaning Characteristics For Rice

The stripping harvesting technique has been utilized on the stripping combine harvester, whose working principles are to strip directly the rice particles growing on the straws in the field, and then to convey them into rethreshing separating and cleaning device, to conduct the consequent operations. Meanwhile, the cutting device is used to cut the straws after stripping, and to convey them aside or rear into the bar. Therefore, it has been characterized with the new structure, less power consumption, higher productivity, satisfactory working reliability, better performances of dis-moisture, less loss and broken rate, etc. At present, the studies on the stripping combine harvester have been generally focused on the cutting device. Most of the rethreshing, separating and cleaning device of stripping combine harvesting is borrowed from the structure and theory of various existing threshing, separating and cleaning devices. Since the mixture ingredients after being stripped within the stripping combine harvester are greatly different from those in the conventional all-feeding and half-feeding combine harvester. So it is necessary to conduct theoretical and experimental studies of the rethreshing separation and cleaning devices with the stripping harvesting techniques.In this paper, the author reviews the structure, merits and demerits of various threshing, separation and cleaning devices and analyzes the features of the structure in current'various stripping combine harvesters. According to the status quo of design and the problem existing in the rethreshing separation and cleaning devices of the current stripping combine harvester and because the stripping combine harvester are greatly different from those in the conventional all-feeding and half-feeding combine harvester, the theoretical and experimental research of the rethreshing separation and cleaning devices with the strippedharvesting techniques are put forward in this paper.On the proper assumptions, the mathematical modeling process of the common tangent-direction-feeding axial-flowing rethreshing separation and cleaning system within the stripping combine harvester were discussed from the views of comprehension and possibility. The distribution of the un-threshing rice amounts, free rice amounts, accumulation rice sort rice amounts along with the axial stripped drum, as well as the relationships among the un-threshing loss, mixing loss and the rethreshing drum length are contained. In the rethreshing separation and cleaning system, particle mixing loss is mainly associated with the stripped drum length of L, un-threshing rice amounts ( broken-head) ofk1, free rice amount of k2 and the functions of u1, u2. The studies greatly deepen theunderstanding of the working laws on the tangent-feeding thresh unit, and induct the theory of the mathematical model suitable for the rethreshing separation and cleaning system within the stripping combine harvester. It is important for the design of current rethreshing separation and cleaning system, which is now mainly based on the empirical design due to the lack of theory guidance.The rethreshing space is identical to single input and double output systems. The inlet is material inlet, where inlet materials are the stripped mixture. The double outlets consist of the equivalent outlet of separation concave, and the straw outlet of the stripped drum. The materials within the rethreshing drum are treated as the variable quality system. Based on the principles of the energy system on the variable quality system, power-consumption model of the material within the rethreshing space has been established. The efficient of power-consumption model of the rethreshing drum depends on the experimental coefficients. Kanavoiski used the experimental methods to give out the value range of (power-consumption experimental coefficients) from 0.4 to 0.45, but he did not theoretically explain what is the value of was. This study theoretically validates the theoretical value as 0.5 and gives the physical meaning of.