农业工程学报2018，Vol.34Issue(2)：10-17,8.DOI:10.11975/j.issn.1002-6819.2018.02.002
砍切式玉米秸秆还田机的设计与试验
Design and experiment of chopping-type maize straw returning machine
摘要
Abstract
In annual double cropping areas in northern China, the straw is directly returned to the field after maize harvest, and the wheat is sown by no-tillage planter. However, the high water content and strong toughness of maize straw result in the low qualification rate of traditional rotary flail knife type returning machine, which can easily lead to straw blocking and thereby affect wheat sowing quality. To address the above problems, in this paper, a chopping method based on the principle of four-bar linkage mechanism was put forward. The maize straw was chopped using ground as the support. A chopping-type straw returning machine, composed of the frame, pressure roller, transmission device and straw cutting device, was developed. The pressure roller was located at the front of the machine, and was designed to press the standing or lying straws forward in the direction of machine movement. The cutting device was at the back of the roller, and was designed to cut the lying parallel straw into segments. To avoid straw blocking, maize straw was chopped into segments with the length less than 6 cm, and the length was half of the narrow row spacing of wheat. Based on theoretical calculation and motion simulation, the size of 4-link mechanism of cutting device was designed and the cutters' movement trajectory was optimized. In 4-link mechanism, the minimum transmission angle was 70°, the maximum swing angle of rocker was 20°, the eccentric distance of eccentric wheel was 80 mm, and the lengths of cutter holder (connecting rod) and rocker were 267.375 and 460.702 mm, respectively. The distance between the rotation center of eccentric wheel and the hinge point of rocker on frame was 526.627 mm. According to the finite element static analysis by using ANSYS software, the maximum stress of the cutter was calculated as 162 MPa generated near the bolt holes on both sides, which met the design requirements. The field performance experiment was conducted in Hebei Province to compare the chopping-type straw returning machine and traditional flail knife type machine. The comparison and research objects included the unqualified rate of straw length, working stability, soil physical property and the subsequent sowing operation effect. The experiment results showed that the average length of the straw with the designed machine was 4.8 cm, the unqualified rate was 6% and the coefficient of variation was 0.209, which were all superior to the traditional machine. The vibration of the designed one was slightly larger than that of traditional one with no significant difference, and both of the machines worked stably. The cutting depth of new cutter reached 7.71 cm averagely, and soil bulk density in 0-10 cm depth decreased obviously. The subsequent wheat seeding experiments were carried out, and the results showed that there was no straw blocking during seeding when the seeder operated on the surface on which the chop-cutting straw returning machine worked, and the coefficient of sowing depth was 92.5% and it was significantly higher than another one. This study provides a new equipment for the maize straw returning in the double cropping areas in northern China, and it is also conducive to the popularization of straw returning technology.关键词
机械化/设计/优化/秸秆还田机/砍切/粉碎长度/四杆机构Key words
mechanization/design/optimization/straw returning machine/chopping-type/cutting length/4-link mechanism分类
农业科技引用本文复制引用
王庆杰,刘正道,何进,李洪文,李问盈,何建怀,鄢雄磊..砍切式玉米秸秆还田机的设计与试验[J].农业工程学报,2018,34(2):10-17,8.基金项目
公益性行业(农业)科研专项经费项目-作物秸秆还田技术(201503136) （农业）
