切流-横轴流玉米脱粒系统改进设计及台架试验

对玉米脱粒过程的研究,理论分析与数学建模存在着理想假设的局限性,整机田间试验受制于系统结构、环境条件而不能深入测试分析。为便于室内研究玉米脱粒过程,以4YL-4/5型收获机脱粒系统为参照,设计了切流-横轴流脱粒试验系统,结构设计模块化,可根据需要更换脱粒滚筒等关键零部件或调整技术参数,以便兼顾开展多种谷物脱粒试验研究。工作参数标定表明,试验台架可满足最高37 k W的工作负载,满足滚筒线速度为0~29.06 m/s、喂入量为0~8.08kg/s的谷物脱粒试验。在入口脱粒间隙为36 mm,出口间隙为12 mm,喂入量为2.6 kg/s的条件下,切流滚筒采用螺旋柱齿结构、横轴流滚筒采用柱齿-板齿结构形式,以不同的横轴流滚筒线速度为测试速度,对含水率在22%~32%的玉米果穗进行脱粒试验,试验表明:切流滚筒的脱粒物质量占比随着含水率的增加而减弱,当含水率在28%以下,切流滚筒与横轴流滚筒脱粒筛分段的脱粒能力几乎相当,当含水率高于28%,切流滚筒的脱粒物质量占比下降明显。脱粒系统在线速度15.84~18.72 m/s和含水率为22%~26%的条件下,籽粒破碎率指标满足国标规定值≤5%。在滚筒线速度为17.28 m/s、含水率为24%~26%区间内,脱粒系统的籽粒破碎率最低,平均值为1.7%。通过脱粒试验台,将玉米脱粒过程的试验研究与田间测试有效结合,可为玉米籽粒收获机脱粒系统的设计提供科学依据。

Improved design and bench test based on tangential flow-transverse axial flow maize threshing system

Abstract: The research on the process of maize threshing, the theoretical analysis and the mathematical modeling have the limitation of ideal hypothesis. The field experiment of whole machine is subject to the system structure or the site and can not be deeply analyzed. Therefore, based on the situation of breeding varieties in Huang-Huai-Hai region, the characteristics of agricultural farming, and the status quo of harvesting machinery, in order to facilitate the study of corn threshing process indoors, with the 4YL-4/5 harvester threshing system, the structural design is optimized, and a tangential flow - transverse axial flow threshing test system is designed. The technical parameters and threshing test scheme of threshing mechanism are studied to reduce the grain broken rate, which is the primary target, and at the same time, we explore the technological potential of the maize kernel harvesting and explore the technical bottlenecks that restrict the industrialization development of maize production in the region. The test bench consists of power system, feeding system, threshing system and auxiliary mechanism, and the structure design is modular, the concave threshing clearance can be adjusted, and different styles of threshing drums or concave plate sieve components can be replaced according to the need, in order to carry out a variety of grain threshing test research. The calibration of the working parameters indicates that the test system can meet the maximum load of 37 kW, and meet the test requirements of the threshing peripheral velocity between 0-29.06 m/s and the feeding amount between 0-8.08 kg/s. Based on the statistical analysis of the biological characteristics of tested maize ear, under the condition that the inlet threshing clearance is 36 mm, the outlet threshing clearance is 12 mm and the feeding amount is 2.6 kg/s, tangential flow feeding drum with spiral tooth structure and transverse axial flow drum with column tooth - plate tooth structure are used to thresh the corn ear with water content of 22%-32%, taking different peripheral velocities of transverse axial flow threshing drum as the test speed. The experiments show that, the threshing capacity of the tangential flow drum decreases with the increase of the moisture content. When the moisture content is below 28%, the threshing capacity of the tangential drum is almost equal to threshing sieving section of the transverse flow drum. When the water content is higher than 28%, the threshing capacity of the tangential flow drum decreases significantly. The grain broken rate index of the threshing system satisfies the national standard of equal to or lower than 5% under the condition of the drum peripheral velocity of 15.84-18.72 m/s and the moisture content of 22%-26%. With the drum peripheral velocity of 17.28 m/s and the moisture content of 24%-26%, the threshing system has the lowest grain broken rate with an average of 1.7%. Through the threshing test system, the theoretical analysis of maize threshing process can be effectively combined with the field experiment, and the related experimental conclusions provide a scientific basis for the design of the corn combine harvester threshing system.